This is silly, but makes some good points. May be good for teachers in your biology class:

This is the molecular biologist Sean Carroll, as distinct from the physicist (who wrote this).

Homeostasis is one of the basic principles of biology. The term can be applied broadly to mean that certain numbers are maintained within a certain range. This could refer to energy flowing through a system, numbers of specific cellular products like enzymes, numbers of individual organisms in an ecological system, etc. It is not so much that numbers don’t change. Change in numbers is often central to a physiological process. But the change is either demanded by a system of regulating numbers, or is a perturbation in a system that is responded to by regulation. Regulation is one of those key concepts that can be applied across pretty much all systems, and provides a powerful point of view from which to understand what is happening in any living system.

Carroll is a molecular biologist, so much of his training and work is about regulation: identifying it, characterizing it, figuring it out. What Carroll has done in this book is to apply this point of view broadly to biological systems, looking at things inside cells and things inside major ecosystems. The title of the book comes from his own experience visiting the Serengeti as a safari-going tourist, in combination with the fact that this particular ecosystem is one of the best studied in the world. Many different scientists studying everything from grass to microbes to lions to antelopes have spent countless hours observing, characterizing, and trying to explain the dynamics of the Serengeti. As Carroll points out, this is true of a number of different ecosystems, and he could well have named his book, “The Lake Erie Rules,” but that would not have been as cool of a name.

So Carroll has done, then, something that is very dangerous and often does not go well. He’s taken insight derived from his expertise in small scale, mostly sub-cellular, biological systems, and using the touchstone of regulation, applied this insight to help observe, describe, and understand biological systems generally, with a strong focus on ecology. When a scientist steps out of their normal realm to do such a thing, we often get something better ignored, because, in fact, it is not easy or, in some cases, appropriate to make this leap. In this case, however, it worked beautifully. Carroll’s book is fantastic, a success story in going form the specific to the general.

It helps that Carroll is a gifted writer, captivating and thoughtful, and highly respectful of the reader.

Carroll brings in the history of thought and research in the relevant areas of physiology, ecology etc. His messages are framed in the larger context of the Earth’s overall health and important environmental issues. He links the subject matter to key central themes in biological theory (such as natural selection and evolution). And this is all done very well.

You’ve seen the synthetic overviews of life and evolution framed in chaos theory, complexity theory, even quantum physics. This is better.

This is a book to give to your favorite biology teacher (high school or college), and that teacher will take from it examples, connections, lessons, ways of telling, that will enrich their teaching immeasurably.

I don’t think the book is available yet, but you can pre-order it.

The clanger cicada (Psaltoda claripennis) is a locust-like insect whose wings are covered by a vast hexagonal array of ‘nanopillars’ — blunted spikes on a similar size scale to bacteria (see video, bottom). When a bacterium settles on the wing surface, its cellular membrane sticks to the surface of the nanopillars and stretches into the crevices between them, where it experiences the most strain. If the membrane is soft enough, it ruptures…

Here’s the model:

Not all bacteria are subject to this effect; it depends on the rigidity of the cell membrane.

Obviously, we want to make all doorknobs and toilet seats out of this stuff.

Pogodin, Et Al. 2013. Biophysical Model of Bacterial Cell Interactions with Nanopatterned Cicada Wing Surfaces. Biophysical Journal 104(4):835-840. The article was published on Feb. 19th in Biophysical Journal. Abstract:

The nanopattern on the surface of Clanger cicada (Psaltoda claripennis) wings represents the first example of a new class of biomaterials that can kill bacteria on contact based solely on their physical surface structure. The wings provide a model for the development of novel functional surfaces that possess an increased resistance to bacterial contamination and infection. We propose a biophysical model of the interactions between bacterial cells and cicada wing surface structures, and show that mechanical properties, in particular cell rigidity, are key factors in determining bacterial resistance/sensitivity to the bactericidal nature of the wing surface. We confirmed this experimentally by decreasing the rigidity of surface-resistant strains through microwave irradiation of the cells, which renders them susceptible to the wing effects. Our findings demonstrate the potential benefits of incorporating cicada wing nanopatterns into the design of antibacterial nanomaterials.

Connecting cilia: cellular antennae help cells stick together

Primary cilia are hair-like structures which protrude from almost all mammalian cells. They are thought to be sensory and involved in sampling the cell’s environment. New research, published in BioMed Central’s open access journal Cilia, launched today, shows that cilia on cells in the retina and liver are able to make stable connections with each other – indicating that cilia not only are able to sense their environment but are also involved in cell communication.

Primary cilia are structurally and functionally very similar to eukaryotic flagella (motile tails used to propel microorganisms). For many decades it was thought that cilia on human cells were primarily for movement, for example, cilia on respiratory cells drive mucous up and out of the airways by beating together, however it is now believed that they are also ‘cellular antennae’ – important for cell to cell communication.

In order to find out how these cilia could physically communicate Carolyn Ott and Jennifer Lippincott-Schwartz, from the Eunice Kennedy Shriver National Institute of Child Health and Human Development, examined primary cilia from the retina, bile duct and in cultured cells. In all cases, cilia between nearby cells formed long-lasting contacts with each other, something that has never been observed before. The adhesions between cilia lasted hours or days and were dependent on interactions between glycoproteins (proteins with a sugar molecule attached).

Jennifer Lippincott-Schwartz explained, “A number of human genetic diseases, including Bardet-Biedl syndrome, nephronophthisis, Joubert, and Meckel-Gruber syndrome, are due to defects in ciliary trafficking and signaling. Our study suggests that cilia are active transmitters and seek out neighboring cells to communicate with. These newly discovered cilia-cilia contacts may be disrupted in ciliopathies, an intriguing possibility that requires further investigation.”

The findings are published in Cilia, a new Open Access journal from BioMed Central. Cilia is a peer-reviewed journal that publishes high quality basic and translational research on the biology of cilia and diseases associated with ciliary dysfunction. Research approaches include cell and developmental biology, use of model organisms, and human and molecular genetics.

Reference: Primary cilia utilize glycoprotein-dependent adhesion mechanisms to stabilize long-lasting cilia-cilia contacts. Carolyn M Ott, Natalie Elia, Suh Young Jeong, Christine Insinna, Prabuddha Sengupta and Jennifer Lippincott-Schwartz. Cilia (in press)

Craig Venter and team make a historic announcement: they’ve created the first fully functioning, reproducing cell controlled by synthetic DNA. He explains how they did it and why the achievement marks the beginning of a new era for science.

Scientists are reporting that they have made a living cell from DNA that was originally synthesized in a lab. This isn’t quite a synthetic organism. But the result is an important, and some would say troubling step on the road to creating life in the lab.

Craig Venter is the scientist behind the effort. Many scientists have strong opinions about Venter, but even his detractors will admit he’s a man who thinks big.

details here

A recent paper in PNAS addresses the size difference between fresh water and marine diatoms. Cell size is potentially a very important variable for these little organisms. For instance, larger cells would, on average, sink more frequently and quickly to the bottom of the ocean, thus sequestering carbon (this carbon is the carbon in the living tissue of the diatom). There are presumably ecological reasons why larger vs. smaller cells would evolve.

It turns out that the size range is greater and the maximum size is larger in marine diatoms compared to fresh water diatoms. Why?

The study considered the role of Nitrogen vs. Phosphorus limitation on cell size. Nitrogen and Phosphorus have different patterns of availability in marine vs. fresh water settings. Nitrogen is probably more of a limiting factor in marine environments, and Phosphorus is probably more of a limiting environment in fresh water environments. Also, the range of depths at which diatoms can survive for longish periods of time is greater in marine environments than it is in fresh water environments. For various reasons, both of these relationships suggest that larger diatoms would do well in marine environments.

When Nitrogen is abundant and consistent, fast growth rates of cells is possible. Whenever it is possible, we expect fast growth rate of tiny organisms to be selected for (unless there is some counteracting effect) because in this way the organisms can grow out of the size range for at least some of their predators. The faster rate of growth leads to smaller maximum size.

Although Nitrogen can be limiting in marine environments, it is also very variable in amount over time Variation in the basic food supply for any orgasm can lead, other things being equal, to smaller body size for space limited creatures like elephants on islands, but for these single celled organisms, variation in body size leads to larger size because of the greater potential for food storage in the larger cells.

Another factor is the importance of sinking. For a diatom, sinking too much = death because these organisms get their energy from sunlight. Physiologically active diatoms don’t sink, but when the cell becomes inactive it may start to sink. In diatoms that are physiologically active (healthy, there’s enough sunlight, etc.) size does not affect sinking rages, but in cells that are less active owing to lack of nutrients or sunlight sinking is quicker in larger cells. However, really large diatoms actually sink more slowly than small ones. Therefore, variation in physiological activity selects for a greater range in diatom size. This is what is probably happening, in part, in marine settings.

In contrast to the situation with Nitrogen, variation in Phosphorus seems to select for small sized diatoms, for reasons that are not entirely clear (so we’ll just skip that part…)

The present study gathered data on diatoms and their environments from a wide range of sources, then used all of these data to run simulation studies testing various ESS strategies. The ESS simulations significnatly refined the understanding of diatom evolution and confirmed and provided detail to the idea that Nitrogen and Phosphorus levels, as well as the effective depth at which diatoms operate, explain through Natural Selection theory what we see in nature.

ESS stands for Evolutionary Stable Strategy. This is an interesting and important concept in evolutionary theory. A strategy is pretty much anything that can be thought of adaptively. Body size is a strategy, a certain foraging pattern may be a strategy, etc. A stable strategy is a strategy that is held in place, such that alternative variants are somehow avoided, over time. An Evolutionary Stable Strategy is one in which Natural Selection has in a sense “chosen” among a set of alternative strategies the one strategy that out does all others with respect to fitness. This strategy … this ESS … is expected to remain as the dominant, in place strategy forever. Or until a new ESS comes along, invading the population and replacing the original strategy. Since evolution works with random mutations as the starting point, the “One True ESS” may not be extant in a given population, but then, when it emerges it should spread. In truth, however, since there are lots of mutations and lots of time, most strategies in most populations are already The One True ESS or close to it. What can happen over time, however, is that conditions change and what once was The One True ESS is supplanted by a similar … but importantly different … strategy that was, in a sense, waiting int he wings as part of normal variation.

Litchman, E., Klausmeier, C.A., Yoshiyama, K. (2009). Contrasting size evolution in marine and freshwater diatoms
PNAS, Early Edition

You must be over 18 to read the rest of tis blog post.

Semen is not only nutritious, but it also has a wonderful texture and amazing cooking properties. Like fine wine and cheeses, the taste of semen is complex and dynamic. Semen is inexpensive to produce and is commonly available in many, if not most, homes and restaurants.

But employees must wash their hands before returning to work …

Despite all of these positive qualities, semen remains neglected as a food. This book hopes to change that. Once you overcome any initial hesitation, you will be surprised to learn how wonderful semen is in the kitchen.

Well, I once knew a sailor who was a really good cook …

Semen is an exciting ingredient that can give every dish you make an interesting twist. If you are a passionate cook and are not afraid to experiment with new ingredients – you will love this cook book!

Recipes include such items as “Almost White Russian” and “Man Made Oysters.”

Which reminds me of the archaeology graduate student who was asked “Name one book by Gordon Childe” and all he could come up with was “That one about masturbation” (thinking of the title “Man Makes Himself.”) … But I digress.

Oh, and Creamy Cum Crepes and Tuna Shashimi with Dipping Sauce.

Continuing with the blurbs:

My name is Paul Photenhauer. My friends call me “Fotie” and you can too. I enjoy food and cooking it – especially when I add a little semen to the dishes I create. No, I’m not joking and no, I’m not some sort of whacky freak.

HA HA HA HA HA HA !!!!!!! YES YOU ARE!!!!!

Oh, sorry …

I’m just passionate about everything I do, including cooking with cum. Thanks for stopping by. I hope you enjoy the book and the blog. I would love to hear what you have to say, so be sure to leave a comment or two!

– Fotie

Here.

OK, I have a couple of questions.

1) How does this relate to a vegan diet?

2) Lent. What do you do during lent?

3) Is there a recipe that involves caviar?

That is all.

Electrically, astrocytes are pretty silent … A lot of what we know about neurons is from sticking electrodes in them. We couldn’t record from astrocytes, so we ignored them.[When astrocytes were imaged with two-photon microscopy] the first thing we noticed was that the astrocytes were responding to visual stimuli. That took us completely by surprise … We didn’t expect them to do anything at all. Yet there they were, blinking just like neurons were blinking. We didn’t know if the rest of the world would think we were crazy.

According to Mriganka Sur, another co-author:

This work shows that astrocytes–which make up 50 percent of the cells in the cortex but whose function was unknown–respond exquisitely to sensory drive, regulate local blood flow in the cortex and even influence neuronal responses. … What’s more, astrocytes are arranged in orderly feature maps, exquisitely mapped across the cortical surface in sync with neuronal maps.

So how did they figure this out? The researchers used a two-photon imaging of calcium signals in the visual cortex of a ferret (in vivo). Calcium would be active during cell activity because of its role in basic cell metabolism.This kind of imaging involves looking at tissue with a fancy microscope that is able to focus on things happening at depth within that tissue. (By “depth” we mean about one millimeter.) The reason this works is rather spooky. Under certain conditions, two photons act in a quantum mechanical way to cause a fluorescent event which can be detected by the two-photon microscope.Schummers, J., Yu, H., Sur, M. (2008). Tuned Responses of Astrocytes and Their Influence on Hemodynamic Signals in the Visual Cortex. Science, 320(5883), 1638-1643. DOI: 10.1126/science.1156120