RICOCHETSCIENCE.COM

When a Book Cover is More than a Pretty Picture

2012-02-24T19:16:44Z

How is a certain species chosen to grace the cover of a textbook? While we would love to think that all species have an equal chance, the truth is that the subjects on the cover are usually selected because of their artistic appeal. After all, even though I am a Drosophila geneticist by training, and love pictures of fruit flies, I realize that most people would prefer to see something like butterflies, flowers or wolves. Dull insects and parasites are out, color is in.

However, for the 11th edition of Biology, I decided to mix it up a bit. The authoring team and I decided that not only would we choose a pretty picture (we are not complete rebels), we would integrate the theme of that picture throughout the text. Why? Because students, like everyone else, like a good story, and educators are probably the best story-tellers on the planet. Our job as teachers is to take a series of usually uninteresting facts and find a way to engage the students. So this edition, we picked a really cool story....

And here is the story.....

The wolf on the front cover is a subspecies of the North American gray wolf called Canis lupus arctos, or the arctic gray wolf. Wolves, like the one shown here guarding a skeleton of a caribou (Rangifer tarandus), historically occupied almost the entire United States. However, wolves were viewed as a hazard by many human groups, and by the 1930s, almost all of the wolf packs in the continental United States had been exterminated. But this is not just the story of the loss of another animal species.

The removal of the wolves began to have a ripple effect on the Yellowstone ecosystem. Without a natural predator, the population size of elk began to expand, and as it did, the preferred food sources of the elks – cottonwood and willow trees – began to dwindle. Cottonwoods especially serve an important role in the Yellowstone ecosystem. This species of tree prefers the banks of streams, where its root system helps stabilize the stream banks, thus preventing erosion and the accumulation of sediment. With the loss of the trees, the aquatic habitats suffered, and for decades ecologists documented the decline of aquatic insect, fish, and bird populations. Over time, scientists were becoming concerned that the food web of the Yellowstone ecosystem was moving towards collapse.

In order to understand the role of the wolves in ecosystems such as Yellowstone, scientists had to piece together information on the evolutionary history of the organisms in the community with an understanding of how the ecosystem functions as a biological system. Coupled with this was some fascinating detective work, with experimental results suggesting that it was the demise of the wolves, and not other ecological factors, that were responsible.

The story of the wolves is a positive one for science. By reintroducing wolves back into Yellowstone in the late 1990s, and closely monitoring not only the health of the wolf population, but also the size and composition of the elk herds, conservation ecologists have been able to document that the Yellowstone ecosystem is beginning to return to a healthy status.

So why did we do this?

Well, within this text you will find that these three same themes – the nature of science, evolution, and biological systems - form the threads that connect the content together. We integrated the cover into the story of biology, and then we built assets around the themes to help the instructors engage their classes. Throughout the text, unit level learning outcomes, feature readings, and new digital assets, are all combined to integrate the themes into the course content. The goal is to enforce the idea that, like the complex interactions of the species in the Yellowstone ecosystem, the many parts of the biological sciences are interconnected, and that by understanding these connections, students can grasp the importance of biology to their lives.

If you are looking for more information on this text, visit us online at:

www.mhhe.com/maderbiology11

Evolutionary Wars and Chili Peppers

2012-01-10T19:55:47Z

In Inquiry into Biology, the opening story for chapter 4 describes why biting into a chili pepper produces a burning sensation in your mouth. This is because chili peppers contain a compound called capsaicin that activates the pain receptors in your mouth, which is interpreted by the brain as the “burn.” And as every chili-head can tell you, not all peppers are equal. While many may think that the chili peppers are producing capsaicin for our benefit, there is a much more interesting story behind this compound.

Chili peppers, and indeed many plants, are in a constant state of war with the fungi. Being nonphotosynthetic, fungi have to get their nutrition from somewhere, and although many fungi are saprophytes (decomposers), there exist a significant number of species that are parasites and pathogens of plants. The sworn enemy of the chili pepper is the fungus Fusarium (spores are shown below), a very common fungus that is widely found in soils.

To combat Fusarium’s threat, chilis produce capsaicin, which inhibits the ability of the fungus to infect the plant.However the production of capsaicin comes at a fitness cost to the chilis. Fitness in biology refers to the ability to produce viable offspring for the next generation, and it is known that plants which produce large amounts of the compound are not able to produce as many offspring. Why? Because the production of capsaicin reduces the ability of the plant to manage its water resources. And with a reduced water-efficiency comes fewer offspring.

But this is where it gets interesting. In general, Fusarium prefers moist environments (although it can live in hot, arid regions as well). So, it would make sense that chilis that are found in dry environments should produce less capsaicin, and more offspring, than their more arid, Fusarium-threatened relatives.

To test this hypothesis, researchers at the University of Washington first sampled chili plants along a 185 line in Bolivia that naturally varied in water availability. What they found was that even in the dry environments there were chilis with high amounts of capsaicin, but they only accounted for about 20% of the population. However, as the environment became wetter, the percent of high-capsaicin producing plants increased, and at the extreme end of the spectrum, in the moistest environments, all of the plants were capsaicin producers.

To test the relationship between water-efficiency and number of offspring, the researchers designed a controlled experiment in which identical populations of chili plants were grown under similar experiments and then exposed to either a normal, or water-stressed, environment. The results confirmed that plants with higher amounts of capsaicin produced fewer offspring. Although the direct link between capsaicin and water-efficiency has not yet been determined, it is evident that production of the compound comes at a fitness cost to the plant.

So the next time you bite into a really hot chili, consider that fact that what you are really experiencing is an ancient arms race between a pepper and a fungi – and that the chili you are eating sacrificed its fitness for your spiceness.

Additional Resources

D. C. Haak, L. A. McGinnis, D. J. Levey, J. J. Tewksbury. Why are not all chilies hot? A trade-off limits pungency. Proceedings of the Royal Society B: Biological Sciences, 2011; DOI: 10.1098/rspb.2011.2091(full text available)

Science360 Radio

2011-12-03T22:46:35Z

If you are involved in science education you know the importance of reaching today's students in the digital world in which they live. It appears that the folks at NSF have also gotten that message in the form of the Science 360 Radio website.

This is a fantastic resource for time-stressed educators. The site provides direct links to over 100 podcasts from a variety of NSF sponsors. Basically, if you are looking for a topic from brain chemistry to bacteria, it is here. Some of my personal favorites include:

Scientific American's 60 Second Series: 60 seconds of updates on a variety of topics, from health to tech. These may be subscribed to in iTunes, or as an RSS feed (which means that that they can be easily inserted into most course management systems). Looking for that way to start the class? Assign one of these the night before a lecture and take the first 5 minutes to talk about it in class.

MicrobeWorld : Featuring reviews of books, information on antibiotic resistance and explorations of some really interesting bacteria - all at a level that is suitable for an intro bio class.

The Academic Minute: This series of podcasts includes interviews with actual scientists who talk about the importance of their work. As always, these scientists display a real passion for their work, which students will quickly pick up on.

But that is not all - you can easily install a widget to add Science360 to your webpage or blog. Ours is up and running to the right (go ahead and click on it and check it out). The link is available from the homepage. There are apps for almost any smartphone and iPads as well. The Science360 folks are covering the spectrum with this site.

Feel free to post a comment with your favorite podcast below - or if there are some missing from the list, let us know and we may feature them on our site in a future post.

Additional Links

Engineering a Better Mosquito

2011-11-19T03:24:10Z

Several years ago, in one of my introductory biology classes, I mentioned that one of the most promising ways to fight diseases, such as malaria, might be to genetically engineer a better mosquito. As you may expect, the looks from the around the classroom were fairly consistent - their usually slightly-off center instructor had finally stepped over the edge. After all, shouldn't we be getting rid of mosquitos, not making them better?

While humans may be fairly adept at driving species into extinction, we seem to have a problem when it comes to mosquitoes. For diseases such as dengue and yellow fever, the mosquito we are dealing with, Aedes aegypti (shown below), has proven to be a formidable foe. The species has a very short generation time (10-14 days), and can reproduce in environments with very small amounts of water (planters and old tires are frequently used). In addition, they have exhibited the ability to very quickly evolve resistance to many forms of insecticides. Despite modern efforts to control this species, it is not only surviving, but doing well.

By James Gathany (PHIL, CDC) [Public domain], via Wikimedia Commons

One of the diseases that this mosquito is involved with is dengue fever. This is a multistage infection. The disease starts off with a high fever, pain behind the eyes, and muscle pain. But the real damage starts to occur about 24-48 hours after the fever breaks, when the capillaries of the body can become leaky, resulting in dengue hemorrhagic fever (DHF) , which may result in circulatory system failure and death. Like many hemorrhagic fevers, there are no medications or treatments.

By Mikael Häggström [Public domain], via Wikimedia Commons

Despite the fact that dengue fever is caused by a virus, there are no vaccinations, and preventive mechanisms focus on avoiding mosquito bites. But since dengue occurs in the tropical regions of the globe, over 40% of the world's population is exposed to the mosquito, and there are believed to be over 100 million new cases per year. Avoidance of mosquito bites for densely populated areas within the range of Aedes mosquitoes is becoming increasingly difficult.

So how does one control the spread of a disease that utilizes a host species that is resilient to most of our efforts? The answer might be not to kill the mosquito, but rather to make it an inhospitable host for the virus that causes dengue. And the secret to this is Wolbachia, a species of bacteria that is a common parasite of many insect species. Wolbachia has been studied extensively in species of insects such as Drosophila (the fruit fly) and it is well-recognized as having the ability to moves rapidly through populations of insects.

Researchers have shown that the dengue virus does not reproduce well within a Wolbachia-infected mosquito. Since dengue fever can only be passed on using the mosquito as an intermediate (there is no person-to-person transmission), if the number of dengue-carrying mosquitoes can be reduced over an extended period of time, it may be possible to break the cycle of infection. This opens up the possibility of actually releasing millions of Wolbachia-infected Aedes mosquitoes into a given area, with the hopes of breaking the dengue-virus life cycle. Trials are currently underway, and if successful, may open up a new chapter in how humans regulate the spread of some of the most deadly diseases on the planet.

Additional Resources

Additional information on how Wolbachia may reduce spread of dengue fever
CDC site on dengue fever, including an interactive map of dengue fever locations

Founder Effect - Minus the Iguanas and Finches

2011-11-07T16:56:53Z

The picture below should be familiar to anyone with a background in biology. The birds shown here are members of the "Galapagos finches", famous for inspiring the work of Charles Darwin, but also used extensively in the classroom to talk about the founder effect.

By John Gould (14.Sep.1804 - 3.Feb.1881) [Public domain], via Wikimedia Commons

The founder effect is one of the fundamental topics of any population genetics lecture, and it used to show how random events (what is called genetic drift) shapes the genetic structure of a population. Finches and iguanas are common examples, but to be honest, most people have heard of these examples so many times that it is getting repetitious. A recent article in Science adds a new flavor to the topic of founder effect.

Recently, researchers at the University of Montreal have examined the relationship between the founder effect and fitness, or the ability to survive and pass its genes onto the next generation. What is interesting here is that their test subjects are not birds, or iguanas, but humans.

What made this study possible was the BALSAC population database, a historical record of almost 5 million events (birth and death certificates, marriage licenses, etc) spanning almost 4 centuries and focusing on the Sagueny Lac St-Jean region of Quebec (an area that was initially colonized by French immigrants in the 17th century).

In this study the researchers investigated what happens to the population immediately after it colonizes a new area and begins to expand its range. Specifically, they examined whether it was better (from a population genetics perspective) to stay in the initial area founded by the population (the range core), or to be part of the group that it expanding into new territories (the wave front). By assessing fitness based on the reproductive success (number of children produced), the researchers found that the group on the wave front of the population made a greater contribution to the genetic makeup of the population's gene pool over time. Fitness, it seems, is correlated more with expansion than staying in one place.

There are lots of applications for this research, not only for recent human migrations, but for the historical movement of hominins across the globe. The success of Homo sapiens, it appears, may be the result of its migration and the resulting founder effects, and the influence of the individuals in the wave front of these populations on the genetic makeup of the species. If nothing else, it provides something to discuss in class other than a finch.

Additional Information:

ScienceDaily article "Evolution During Human Colonizations: Selective Advantage of Being There First"
Claudia Moreau, Claude Bhérer, Hélène Vézina, Michèle Jomphe, Damian Labuda, and Laurent Excoffier. Deep human genealogies reveal a selective advantage to be on an expanding wave front. Science, 2011 DOI: 10.1126/science.1212880

Tweeting for the Online Classroom

2011-09-05T02:52:26Z

Communicating with your online students can be challenging. While most course management systems (CMSs or LMSs) have discussion boards and email capability, the reality is that somehow as an instructor you need to drive them onto the site to get the course information -for as we all know, students will not "surf" course pages.

One solution is Twitter. In my Human Genetics class, which has been taught as both a hybrid and online course for the past five years, I use a Twitter site to inform the students of upcoming events such as assignments, quizzes, and tests.

Some best practices for using Twitter for this audience:

Provide specific instructions on how to set up a Twitter account

While the 18-25 age group may be the social network generation -the reality is that most of them do not have a Twitter account, nor even understand why they might want one. At the start of each semester I post a pre-course checklist that contains instructions on how to set up a Twitter account and subscribe to the course Twitter site. It is important that this checklist contain screenshots of exactly how to setup their accounts. Increasingly, I am abandoning the checklist aspect of the course in favor of video tutorials on how to set up and use an account.

One thing that you want to inform your students of is the fact that they do not need to have your course tweets sent to their cell phones - especially of they do not have unlimited text messaging on their cell phones. Instead, I inform the students that they can set up programs such as Tweetdeck that allow them to subscribe, and filter, a variety of Twitter sources.

One additional note on Tweetdeck - it provides an easy way for an instructor to not only manage multiple Twitter accounts, but to also post information rapidly to their students. If you are going to use Twitter in your classes, I highly recommend the Tweetdeck program (and iPad app as well).

Limit the number of tweets and tell your students how to follow them

The last thing that your students want to know is what you are up to this weekend, or your political views on a certain candidate. Therefore, you need to limit the number of tweets that you send each day - and make them specific for the course.

For my course, I send out one tweet per day (usually Monday-Friday) informing the students on what is coming up over the next few days, due dates for assignments, etc. Occasionally I include tweets about current event topics that are related to the current course content - but it is important that you make it relevant to the current material, otherwise you are simply bombarding them with tweets - and that is not the goal of the course Twitter site.

Set up a second Twitter site for your other posts

On the course checklist I inform my students of a second Twitter site, RicochetScience, that they can subscribe to for information on a variety of sources. Most students actually pursue this option, but since it is not required, they do not feel obligated to read every link or tweet.

While there are many ways of communicating with your students using social media - the use of a Twitter account is by far one of the easiest for both the instructor and the student.

Additional Links

ASU Genetics Twitter Site - for the Human Genetics course at Appalachian State
Ricochet Science Twitter site science- weekly updates on news for the introductory science classroom
Tweetdeck website

LearnSmart in the Classroom: Setting up a Class

2011-08-21T22:26:36Z

First of all, what is LearnSmart? Basically - LearnSmart is an adaptive learning platform that provides a student-centered assessments of learning. In other words - the program responds to what the student does and does not know, and designs a custom learning path to allow the student to obtain certain learning objectives.

While I have given numerous workshops on the benefits of LearnSmart, I have also discovered that many instructors do not yet know how to effectively assign LearnSmart for their students. They make the mistake of assigning too much material, or weighing it too heavily in their final grades. The instructors at my institution have requested that I outline a series of steps to get them into the program. Below, I have provided a brief overview that will allow an instructor to quickly and easily engage their students in the LearnSmart platform. Please note that this is just one set of guidelines on how to use the program - after you become familiar with the system, you should feel free to experiment and develop your own, course-specific best practices.

Step 1: Assigning Content

In my classes I use LearnSmart to get my students prepared for the lecture, be it virtual or traditional. Therefore, the initial assignments usually focus on the core terminology and concepts of the chapter. I have found that if I can get the students to understand key terms and concepts before class, I can spend more time developing the more difficult concepts and applications.

Most of the time - the core concepts are located in the first few major headings of the chapter (10.1, 10.2, etc). Therefore, for the pre-class assignment, I only assign those sections of the text (Step 4 will show you how to integrate the entire chapter).

The other key item in generating an assignment is to give the students time to complete the work. The goal is not to overwhelm them in scientific terminology, but to build a foundation. Therefore, using the slider bar I usually set the assignment for around 20-30 minutes average worth of work.

As you move the slider bar from right to left, you are increasing the focus on the core materials, and reducing more of the application-related content.

Step 2: Due Dates

For due dates - when possible, I assign LearnSmart material 5 days prior to the lecture. This allows the student, who increasingly has a busy schedule of classes, work, and family, ample time to complete the assignment. One of the nice aspects of LearnSmart is the fact that you do not need to complete the entire assignment at one time - so 20-30 minutes of work can easily be spread over a few days if needed.

I also always assign the same time each day for the assignments to be due. I happen to choose 1155pm (never choose 12 pm, too easily confused with 12 am), but other instructors choose the start of class for their traditional or hybrid courses. Be consistent and you will greatly reduce the number of emails from your students!

Step 3: Assigning Points

My goal for using LearnSmart is to develop an understanding of how the course material - a foundation on which I can build more difficult concepts. Therefore, I award points based on 100% completion. If you complete 100% of the LearnSmart assignment - you get 10 points towards the module grade (usually 100 or 200 points total in my classes). The eliminates the focus on right/wrong, and greatly reduces the student appeals of specific cards.

Step 4: Entering the Playground

Even though I do not assign all of the sections, I encourage the students to work on the complete chapter in LearnSmart before their exams. Actually, most of my students request this feature.

To access the complete chapter, simply enter what I call the "playground" . On each Connect site, in the lower right is an icon similar to the one below. By clicking on this icon, the students enter the LearnSmart program for the entire book.

One note of caution - it is important that you inform your students that assignments need to be completed from the Assignment list, and not from within the playground, since no grades are recorded from within the playground.

In later postings, I will discuss how you can run reports using LearnSmart, and how these reports can transform your classrooms from an instructor-focused environment to a student-centered learning arena that utilizes both adaptive learning and adaptive-taching strategies.

If you are a user of LearnSmart, I also encourage you to enroll in The Connect Community, a site where you can find active discussions on adaptive learning, case studies on classroom effectiveness, and more importantly, a community of educators who are exploring new ways of interacting with students.

Additional Resources

RicochetScience YouTube Channel
Information on the LearnSmart program (McGraw-Hill)
More information on adaptive learning (Trainingplace.com)
The Connect Community website

Looking for Videos? Try these...

2011-06-17T00:14:00Z

There is a paradox in ecology education. The fact is that most students are very interested in the diversity of life on the planet - that is why they take biology rather than chemistry or physics for their general education requirements. But, when most professors get to the biodiversity lectures, they run through an seemingly endless series of PowerPoint slides of different organisms. And to be honest with you.. PowerPoint slides are not all that interesting.

So, how do you get across the wonder of life, and the importance of biodiversity, if you are confined to a series of jpeg images captured off of Google? The answer, of course, are videos. There are some great videos out there - Life (Discovery Channel), Great Migrations (National Geographic), and Planet Earth (Discovery Channel) - just to name a few. But most of these are too long for use in a traditional classroom, and most instructors want to focus on a specific animal.

BBC Nature has put together a tremendous resource for teaching biodiversity. It is called the BBC Nature Wildlife site, and it not only contains a downloadable tree of life, but also links to information on plants, fungi, and animals.

But perhaps the best asset on this site are the for the animals. There are videos for almost every type of animal, from the cnidarians to the vertebrates. All of these videos bring the animals to life, and portray them in their natural environments.

But what about extinct animals? How about a video of Archeopteryx narrated by David Attenborough?

There are videos on Neanderthals, and prehistoric amphibians and reptiles. Many of the videos (like the Archaeopteryx video above) many easily be embedded into any course management system. Each group contains a link to the Tree of Life Web Project - a site that is rapidly becoming an invaluable resource in science education.

So if you are looking to engage your students.. check out the BBC Nature site and see what happens

Bringing Planctomycetes to the Classroom

2011-06-11T22:05:18Z

What are the general characteristics of a prokaryote shown below? Lack of a nucleus? Cell walls made of specialized sugars called peptidoglycans? Lack of membrane-bound organelles? All of the above?

from Essentials of Biology 3e - used by permission

What about none of the above? What if we found a prokaryote that lacked all of the items listed above, but was by all other characteristics, a prokaryote? What would that tell us about the evolution of the bacteria?

Many times in the classroom we are ask students to take an evolutionary "leap of faith". Since bacteria do not easily form fossils, then we may never really find the elusive link between the prokaryotes and eukaryotes. The evolution of the eukaryotes is a logical series of events, shown nicely by the endosymbiotic theory - but to be truthful, something tangible that we can point to in the classroom has been hard to come by. There has always been Giardia, the parasitic eukaryote (protistan) that lacks a mitochondria, but most evidence suggests that Giardia evolved from a eukaryote that possessed a mitochondria - so it is probably not our missing link.

However, scientists at the University of Queensland have identified a group of bacteria - called the planctomycetes, that are closer to a missing link than anything we have had in the past.

Planctomycetes are an interesting group of bacteria. They possess a form of intercellular compartments that appear to have specialized metabolic functions. One of these, called an anammoxosome (breaks down ammonia) that appears to have a similar function to the eukaryotic mitochondria. The DNA of a planctomycetes is contained within a membrane-bound nucleoid region - not quite a nucleus, but it definitely represents an internal compartment for the genetic material. Also, most of the planctomycetes lack peptidoglycans (a sugar-amino acid combination) in their cell walls. The presence of peptidoglycans is a defining characteristic of bacteria in general, and is the target of many forms of antibiotics - the fact that the planctomycetes are lacking this compound suggests that they are not a common form of bacteria. In addition, planctomycetes tend to (but not always) reproduce by budding instead of binary fission. Yeasts, a one-celled eukaryote, reproduce by budding. (Looking for a comparison of a planctomycete with a common bacteria?- download our PowerPoint for use in the classroom)

And it seems that these important bacteria may have been right under our noses for some time, for the planctomyctes are found almost everywhere. They are found in aquatic and terrestrial environments, in caves and in fecal material. and in both oxygen-rich and oxygen-poor environments. In other words, they are pretty common.

So what does this mean? As pointed out by the researchers at the University of Queensland, too often model organisms, such as E. coli, are used as the basis for lectures on bacterial physiology. And while there is a place for the model organisms, the exclusive use of them does not help our audience understand the wonderful complexity and diversity of the prokaryotes. When students see an E.coli under a microscope, they have a hard time making the connection of how this type of organism evolves over time to become a significantly complex eukaryotic cell. But if we show them that there are examples in nature of more complex prokaryotes, some of which may be the missing link, then we can help them make the connections they need in order to understand how complex life evolved from simple, one-celled organisms.

Additional Resources

Fuerst, J., & Sagulenko, E. (2011). Beyond the bacterium: planctomycetes challenge our concepts of microbial structure and function Nature Reviews Microbiology, 9 (6), 403-413 DOI: 10.1038/nrmicro2578
Tree of Life (Web) entry for Planctomyctes
Planctomycetes PowerPoint file comparing the planctomycetes with a common bacteria
Classroom handout (pdf)

Current Event Resources from RicochetScience

2011-05-22T15:54:13Z

As I have been traveling across campuses this spring I have had many requests for resources to integrate current event topics into the classroom. Most instructors do not have time to look daily for level-appropriate resources, so the staff at RicochetScience have prepared several resources to help you quickly get the content you need.

One of these is Delicious - an online bookmarking site that allows users to set up networks and share bookmarks.

The RicochetScience Delicious site was set up specifically for introductory biology and genetics courses. Several times each week I update the site with links from Science, Nature, the National Science Foundation, EarthSky and other websites. Each of these are tagged by topic (see below) allowing you to quickly find relevant, current-event topics for your classes.

A really nice tutorial for using Delicious in the classroom is available on YouTube

Once you have subscribed to Delicious, you can easily set up RSS feeds (see link on the bottom of each Delicious site) and import these directly into your course management system. For example, in Connect, all you have to do is click on the RSS feed icon on the bottom of your course and enter the RSS feed URL.

For those of you who are still looking for additional resources, you can also generate RSS feeds from the RicochetScience Twitter site or the MaderBiology twitter site. The RicochetScience Twitter contains daily updates on a number of topics associated with introductory biology, whereas the MaderBiology Twitter site contains areas specific for the Mader series of textbooks from McGraw-Hill. Both of these contain appropriate content for your course management systems.

Of course, you can always link directly to this blog using any of the links to the right.

Additional Links

Unveiling the Origins of the Plants

2011-04-24T19:36:00Z

While it is clear that plants evolved from a green algal ancestor some 470-500 MYA, the question has always been.. which one? We know that plants and the green algae share the same photosynthetic pigments (chlorophyll a and b), store their energy as starch, and contain the fiber cellulose in their cell walls. But that is a general description for many of the green algae. After all, there are lots of green algae, from the mobile Chlamydomonas to the multicellular Ulva. Saying that the ancestor of the plants was a green algae is like saying that your ancestors came from Europe, a nice general statement, but it really doesn't tell you much about who you are.

Biology, 10th edition - McGraw-Hill Publishing, used by permission

A team of researchers out of Germany and Canada have provided a possible answer to this question - a group of conjugating algae that includes Spirogyra. Conjugating green algae reproduce sexually by temporarily linking the cytoplasm of two cells, allowing the exchange of genetic information. By studying the genomics of over forty different types of green algae, the researchers were able to construct an evolutionary tree that suggests that Spirogyra, or its close relatives, were the ancestor of the green plants. (these trees are available online)

Spirogyra is no stranger to the introductory biology classroom. Since it is easy to culture and observe, it is a common specimen in freshman labs. Furthermore, as can be seen in the video below, it has a unique configuration of its cloroplasts that gives the organism its name.

So the next time Spirogyra is mentioned, don't consider it just another green algae. Instead, think of it as one of those pivotal species that played an important role in forming the ecosystems that are the basis of our modern world.

Additional Links

EarthSky article on Spirogyra and plant origins
EOL page on Spirogyra
BMC Evolutionary Biology paper "Origin of land plants: Do conjugating green algae hold the key?"

National Geographic: Animals of the Galapagos

2011-03-30T01:07:00Z

We all recognize that the Galapagos Islands hold a special place in the life sciences. As one of the two birthplaces of the principles on how evolution shapes populations (the other being with Wallace in Indonesia), the Galapagos are the focus on many lectures. Now, the National Geographic Society has brought the wildlife of the Galapagos to life in a series of fantastic images.

National Geographic image

Now, if you are looking for more information on each of these, check out the links below, all from the Encyclopedia of Life website.

Blue footed booby
Bottlenose dolphin
Hammerhead shark
Red-footed booby
Green sea turtle
Black-browed albatross
Marine iguana
Galapagos tortoise
Hawksbill sea turtle (not much information yet on this species on EOL)

King Henry VIII and the Kell Blood Group

2011-03-18T12:51:00Z

King Henry VIII
(Hans Holbein the Younger [Public domain], via Wikimedia Commons)

A recent article on the DiscoveryNews website (King Henry VIII's Madness Explained) suggests that King Henry VIII's problems, and there were many of them, might be attributed to an X-linked disorder called McLeod syndrome and a rare blood type (Kell Positive) .

Since I am always on the lookout for new information to bring into the classroom, and I have grown tired of the usual hemophilia X-linked trait and the discussions of Rh factors, this article presented the chance to find out a little more about McLeod syndrome and Kell Positive. Plus, it always helps to have a colorful character to relate to, and the life of King Henry VIII certainly satisfied that criteria.

McLeod Syndrome

McLeod syndrome is rare X-linked genetic disorder (in a gene called XK; chromosome location Xp21.1) that produces a distorted form of red blood cell (RBC) called an acanthocyte (star-shaped cell - see below).

By Rola Zamel, Razi Khan, Rebecca L Pollex and Robert A Hegele [CC-BY-2.0 (www.creativecommons.org/licenses/by/2.0)], via Wikimedia Commons

The XK gene is what is responsible for the synthesis of a protein that is active in a large number of cells, including those of the muscles, brain, and heart. The exact function of this protein is not yet known, but it appears to be involved in facilitated transport into or out of the cell. In addition, on RBCs, the XK protein in the formation of the Kell blood group - individuals who are Kell-positive have a defective XK gene lack the XK protein, and this appears to cause the odd-shape of the RBCs (although how is still a mystery). These cells can play havoc within normal circulation within the small boundaries of the capillary beds.

Back to Henry VIII

So what does this all have to do with Henry III? Historians have struggled for some time to determine what ailed Henry VIII. He suffered from a wide variety of disorders - weakness in his muscles and skin ulcers, as well as depression, bouts of anger, etc. It is believed that he suffered a series of strokes before he died as well. Some experts believe that root disease was syphillis (after all - King Henry VIII was known for his active sex life), but another explanation may be Kell Positive syndrome. This blood group may also explain the frequent miscarriages by his wifes, since the Kell blood group can produce pregnancy complications similar to those found in the Rh blood group. For if Henry VIII was Kell-positive (only 9% of Caucasians possess this trait), and his wives were Kell-negative (which is probable), then he would pass the Kell-positive allele to the fetus (since this is an X-linked trait, and Henry VIII is a male), which potentially could cause an immune reaction against it by the woman's tissues, resulting in a miscarriage. Since Kell-positive also produces the spiked RBCs, this could explain Henry VIII's other symptoms.

Of course, we may never know if Henry VIII was Kell-positive, but it does provide an interesting way of discussing both blood groups and X-linked traits in the classroom.

Additional Information

Two New Textbooks from Ricochet Productions for Spring 2011

2011-03-12T12:32:00Z

Ricochet Creative Productions, the parent company of the Ricochet Science blog site, is proud to announce the release of two new textbooks for spring 2011. Both of these textbooks represent the next generation in Dr. Sylvia Mader's introductory biology series of texts. We have prepared two short videos that highlight some of the enhancements and changes that are present in both texts:

Essentials of Biology - Third Edition:

multimedia integration of animations, MP3 files and videos
learning outcomes that may be digitally assessed using the Connect platform
enhanced coverage of evolution
application readings designed to engage your students.

Human Biology - 12th Edition:

multimedia integration of animations, MP3 files and videos
learning outcomes that may be digitally assessed using the Connect platform
enhanced coverage of human disease, with a focus on new introductory case studies
increased discussion of the genetic basis of human disease
application readings designed to engage your students.

If you are interested in more information on these textbooks, or in the development of videos or animations to support your projects, visit our website at www.ricochetprod.com.

Additional Information

Variations in Meiosis: The Parthenogenetic Lizards

2011-03-05T13:58:00Z

For most students in introductory biology, the diagram below is a familiar one. it represents the process of genetic recombination (crossing-over) during prophase I of meiosis. Effectively, this is the first step in the shuffling of the genome in meiosis - and it represents a very important first step in the generation of variation. And, as most students can tell you, crossing-over occurs between non-sister chromatids of homologous chromosomes. Why? Because while the homologous chromosomes are similar (one comes from each parent), the alleles of the genes that they contain may be slightly different - thus the mixing of the two can result in new genetic combinations.

Essentials of Biology, 3rd edition; MHHE .

Usually, I get a question from the group as to whether crossing-over can occur between the sister chromatids themselves. After some discussion, we usually come to the conclusion that this would defeat the purpose of crossing-over, since the sister chromatids are genetically identical. But then the picture becomes a little more cloudy when they are told that crossing-over does occur between the sister-chromatids. So therefore, if one of the purposes of meiosis is the introduction of variation, then why conduct crossing-over between what are effectively cloned pieces of DNA?

A paper I came across Nature from last year explains a potential reason why - if you are a parthenogenetic species (reproduction without males), you lack the ability to obtain genetic variation from your mate. Over time, this effectively limits the amount of genetic variation in the species - never a good thing from an evolutionary perspective. However, researchers from at team at the Howard Hughes Medical Institute discovered that in a parthenogenetic species of lizards (whiptail lizards; genus Aspidoscelis) that crossing-over does occur between the sister chromatids. Furthermore, this crossing-over is responsible for the maintenance of genetic heterozygosity (containing 2 different alleles) in the species.

How does this occur? To make this possible, the species doubles the number of chromosomes prior to meiosis - effectively making an additional copy of the genome and forming a pair of homologous chromosomes from a single parent. This doubling allows the reduction division in meiosis to produce diploid (2n) gametes, a requirement for many species that undergo parthenogenesis. Then, the species allows for crossing-over to occur between the sister chromatids themselves. Since there are always slight differences in the sister-chromatids (they are never truly identical), small amounts of variation are maintained in the genome, and this is passed onto the next generation. As the author's note, a better understanding of this process may lead to insight on the processes of the evolution of sexual reproduction.

It should be noted that this paper is well-written and could be used in an introductory genetics or cell biology course. The methods are well-presented and the graphics and images would be very useful for students.

Additional Links:

McGraw-Hill Animation - How Meiosis Works

Lutes, A., Neaves, W., Baumann, D., Wiegraebe, W., & Baumann, P. (2010). Sister chromosome pairing maintains heterozygosity in parthenogenetic lizards Nature, 464 (7286), 283-286 DOI: 10.1038/nature08818

BBC site on parthenogenetic species . Includes pictures of the whiptail lizard.

How Many Genes? For the Water Flea - More than any other Animal

2011-02-12T23:14:00Z

Meet the animal with the largest known number of genes .... the water flea, Daphnia pulex.

Credit: Paul Hebert, University of Guelph

With over 31,000 genes, Daphnia has over 8,000 more genes than Homo sapiens. But what is even more interesting is the fact that, according to the researchers at the Daphnia Genomic Consortium , almost 10,000 of these genes have not been previously described in any other animal.

So why are scientists working on sequencing the genome of a water flea and what are the physiological roles of those 10,000 mystery genes? To get a better understanding, it is important to recognize the role of Daphnia in the natural world.

Although called a flea, Daphnia is actually a crustacean - same as a shrimp or lobster. However, Daphnia is small (around 0.5mm in size), and while it can feed on other animals, it mostly gets its nutrition by filter-feeding on the algae of aquatic habitats. Thus, as a filter-feeder, Daphnia sits very low in the food web and itself serves as a food source for many other organisms. Filter-feeders are also usually the first organisms in an ecosystem to be impacted by environmental stress, such as chemical or thermal pollution. Many scientists use Daphnia as model organism for understanding how chemicals influence the life cycles of invertebrates, and some have suggested that Daphnia could be used commercially as a type of environmental "stress-test"

It also appears that Daphnia's genome is very rapidly evolving, duplicating genes at a rate that is 30 times higher than than of humans and 3x higher than other known invertebrates. Why? The researchers of this study think that this is an indicator that Daphnia is responding to environmental stress, most likely caused by chemicals in their environment. We already know that Daphnia respond to a wide-variety of chemicals in the environment, including nitrogen , but until this study, those responses were believed to be mostly the result of changes in gene expression.

Daphnia has long been a model organism for the study of aquatic toxicology. These new findings suggest that it may also play an important role in developing an understanding of how the genome and environment interact - a relatively new area of science called environmental genomics.

Teachers or students - if you are looking for a quick way of presenting this information, download the PowerPoint slide "Daphnia Genome" using the link below.

Additional Resources

Ricochet Science Daphnia Genome PowerPoint Slide
YouTube video of Daphnia heartbeat
RicochetScience post on Daphnia and imbalances in the nitrogen cycle
MP3 interview (podcast) by Science Magazine
Colbourne, J.,et al. (2011). The Ecoresponsive Genome of Daphnia pulex Science, 331 (6017), 555-561 DOI: 10.1126/science.1197761

Using Isotopes to Screen for Alzheimers Disease

2011-01-23T14:54:00Z

If you are looking for a new way to introduce how isotopes are used to diagnose disease in medicine, then a recent decision by the FDA to approve a new text for Alzheimer's disease .

One of the symptoms of Alzheimer's disease is an accumulation of a protein in the brain called beta-amyloid. In patients with Alzheimer's, beta-amyloid deposits form between the neurons, forming structures called plaques (the tangles of Alzheimer's disease are caused by a second protein - tau). It is still unclear as to whether the formation of the plaques are a cause of Alzheimer's, or the result of some other stress on the brain, but many researchers believe that these plaques somehow interfere with the normal communication systems within the brain, resulting in the symptoms of Alzheimer's including memory loss and dementia.

Alzheimer's has traditionally been diagnosed using a PET (positron emission tomography ). Until recently, this procedure has relied on the use of a radioisotope of carbon called carbon-11. Unfortunately, carbon-11 has a half-life of around 20 minutes, meaning that the hospital had to have the facilities to manufacture it on site. However, a new diagnostic test, designed by Avid Radiopharmaceuticals, uses radioactive fluorine to detect the presence of beta-amyloid.

A PET scan of the brain

Image source: US National Institute on Aging

So how does this test work? As you can see from the periodic table, fluorine normally has an atomic mass of 19.

The element Fluorine
image by Daniel Mayer

The isotope in the Avid test is Fluorine-18, which decays to form oxygen-18, a stable isotope of oxygen. F-18 has a half-life of around 109 minutes. This longer half-life means that F-18 can be manufactured off-site and shipped overnight to the hospital, greatly reducing the costs of the tests.

Several hurdles still exist - namely whether radiologists can develop standards on how to read the F-18 test results, but the FDA decision may allow for the development of a faster, cheaper, diagnostic test for this disease. At the same time, it presents a unique method of introducing isotopes into the classroom.

Additional Links

NY Times article on FDA decision (January 20, 2011)

Clark, C., Schneider, J., Bedell, B., Beach, T., Bilker, W., Mintun, M., Pontecorvo, M., Hefti, F., Carpenter, A., Flitter, M., Krautkramer, M., Kung, H., Coleman, R., Doraiswamy, P., Fleisher, A., Sabbagh, M., Sadowsky, C., Reiman, P., Zehntner, S., Skovronsky, D., & , . (2011). Use of Florbetapir-PET for Imaging -Amyloid Pathology JAMA: The Journal of the American Medical Association, 305 (3), 275-283 DOI: 10.1001/jama.2010.2008

Essentials of Biology Third Edition

2011-01-14T11:51:00Z

We are proud to announce the release of our first textbook with McGraw-Hill Publishing . Essentials of Biology 3rd edition represents the culmination of a long collaboration between Ricochet Creative Productions and McGraw-Hill Higher Education. Once of the things that the authoring team of Michael Windelspecht (Appalachian State ) and Lynn Preston (Tarrant County College ) focused on was the design of new application materials, and the integration of digital assets. With a realization that today's students are increasingly digitally-orientated, the authors added numerous references to animations, video clips and mp3 files, while retaining Sylvia Mader's recognized style of clear and concise writing.

And what about the cover? This beautiful insect is a species of glassing butterfly from Costa Rica. Here is some more information on it from the back cover of the book:

"The butterfly on the cover of the magazine is called an espejito by the residents of Central America. In Spanish, espejito means “small mirrors”, and in English, this group of butterflies is commonly called the glasswings. Scientifically, glasswings are members of Pteronymia species, a group within the Ithomiinae family of insects.

The glasswings are commonly found in the cloud forests of Costa Rica and Central America. Most cloud forests are tropical rain forests, and are characterized by an almost constant cloud cover and 100% relative humidity. Cloud forests play an important role in regional water cycling, and their constant climate, and access to ample amounts of rainfall make them hotspots of biodiversity. For example, Monteverde Cloud Forest in Costa Rica, home to several species of glasswing butterflies, is known to house over 5,000 species of moths, and tens of thousands of species of other insects.

Most butterflies are brilliantly colored, and this coloration serves to either camouflage the insect within its surroundings, or to act as warning to predators that the organism contains poisonous compounds. Many species of glasswing butterflies have evolved defense mechanisms that employ both tactics. The translucent wings help the insects blend into the background. However, in some cases, the males of the species display colorful bands, such as the orange edges of the cover specimen’s wings. These colors are obtained by consuming the nectar of plants (such as the Asteraceae plant on the cover) that produce alkaloid chemicals, a form of natural toxin. Males of the species have evolved methods of protecting themselves from these chemicals – the orange colors are a warning to predators that eating a glasswing may be hazardous to the predator’s health."

Please feel free to contact the authors for more information on this text.

RicochetScience is now on Kindle

2010-12-27T17:50:00Z

RicochetScience has recently been added to the KindleBlogs site at Amazon.com. So if you are a Kindle user, and want the RicochetScience content delivered to your device each week, visit the link below.

Make sure that you come back to this website often in 2011 as we start to unveil podcasts and more resources for science teachers!

RicochetScience on KindleBlogs

iPad Apps for Biology

2010-12-26T15:29:00Z

This is going to be the first in a regular series of posts of how instructors can start to use the iPad in introductory science courses. We all know that the iPad is a great entertainment platform, and is increasingly being used in the business world. So how about the sciences - and especially for teaching biology? After all, according to the Apple website , there are over 300,000 applications available for the iPad (that number is probably a little low, since new applications are being added almost daily) - however, most of us do not have the time and money to review them all.

So lets start with an application that makes our lives as instructors easier. Many of us already use RSS feeds from journals, magazines, and blogs as a way of keeping up with advances in our chosen specialties. However, reading through a long list of RSS feeds using a program like Google Reader is, at best, boring. An iPad app helps solve this problem. The app is called FlipBoard - and it was named the 2010 App of The Year by Apple.

What Flipboard does is to convert the Twitter feeds of popular sites into a magazine-like format. For example, both of the journals Science and Nature have Twitter feeds of journal contents and recent news (see links below for addresses). By adding these feeds to your FlipBoard site - you develop a virtual magazine of recent posts.

Each entry within the "magazine" is linked directly back to the website of the source. Furthermore, these are highly visual pages, with images enhancing the posts in a way that is not possible with an RSS feed directly. Individual entries can be reposted to Twitter or Facebook pages with a single click - making sharing of the information quick and easy. No more scrolling through pages of tweets, or worse yet- having updates sent as text messages to your cell phone (I made that mistake for about 10 minutes once!). When you are ready to read the tweets from your favorite organizations, all you have to do is open the app and then flip through the pages. There is no doubt that Apple was on the money about this being the App of the Year.

If you add this application - check out the RicochetScience Twitter feed . There we will be posting links to all sorts of articles, websites, and interactive materials that are useful for teaching introductory biology.

If you have a favorite app, or would like for me to review an app for potential use in the classroom, drop off a comment below. Be sure to include your email so that I can contact you for advice, your opinion, or with any questions!