Research Blogging - Biology - English

Offshore Drilling Helps Microbiologists Study Life on Earth and Beyond

2013-05-22T14:55:00Z

Offshore drilling is often discussed in terms of its positive effect on the economy and the potential risks it carries for the environment. There’s, however, another side to offshore drilling, one that is less often talked about....

Parnell, J., Boyce, A., Hurst, A., Davidheiser-Kroll, B., & Ponicka, J. (2013) Long term geological record of a global deep subsurface microbial habitat in sand injection complexes. Scientific Reports. DOI: 10.1038/srep01828

Marijuana and Diabetes: Does Pot Make You Thin?

2013-05-22T14:01:05Z

Teasing out the insulin effect. On the face of it, the study seems to come out of left field: A group of researchers claimed that marijuana smokers showed 16 per cent lower fasting insulin levels than non-smokers. The study, called “The Impact of Marijuana Use on Glucose, Insulin, and Insulin Resistance among US Adults,” is in press for The American Journal of Medicine. The authors are a diverse group of medical researchers from Harvard, Beth Israel Deaconess Medical Center, and the University of Nebraska College of Medicine. The study concluded: “We found that marijuana use was associated with lower levels of fasting insulin and HOMA-IR [a measure of insulin resistance], and smaller waist circumference.” Of course, it was that last tidbit about waist circumference that was picked up by the media. “Why Pot Smokers Are Skinnier,” headlined the Atlantic. However, the important implications are not so much for weight control, or the discovery of some built-in offsetting mechanism for the marijuana munchies, but rather for insulin control and the treatment of diabetes. But in a clinical study, remarkable observations require remarkable documentation. What does the research actually say? There are problems with the study worth noting. While researchers took blood samples after a 9-hour fast to determine insulin and glucose levels, they relied on self-reporting for marijuana use data. And self-reporting for alcohol and drug use has its limitations as an investigative tool. Namely, lack of honesty. But let’s get beyond that for a moment: From a database of 4, 657 men and women who participated in the National Health and Nutrition Examination Survey, the researchers determined that 579 were current marijuana users, while 1, 975 were pot smokers in the past. The marijuana-smoking cohort tended to be young males who also smoked cigarettes. After running everything through a series of complicated multivariable-adjusted models, marijuana came out associated with lower insulin levels, and “lower waist circumference” than those who reported never using marijuana. And the results didn’t change much after adjusting for BMI numbers and excluding participants who actually had diabetes. Furthermore, the association was strongest in current smokers, “suggesting that the impact of marijuana use on insulin and insulin resistance exists during periods of recent use.” (It should also be noted that other health habits can effect glucose and insulin activity, including cigarettes, alcohol, and lack of physical activity.) The investigators don’t offer a solution to the increased appetite/decreased waistline conundrum they claim to have identified. “We did not find any significant associations between marijuana use, and triglyceride levels, systolic blood pressure, or diastolic blood pressure,” they concluded. We know marijuana has a complicated relationship with appetite mechanisms, as evidence by its use with chemotherapy patients who need to eat. The theory is that the metabolic effects are mediated by a complex mix of cannabinoid type 1 and type 2 receptor interactions, since type 1 receptor antagonists like rimonabant improve insulin resistance in humans, and type 1 knockout mice also show resistance to diet-induced obesity. Does marijuana smoking protect against diabetes? Wisely, the researchers don’t go that far, on the basis of this one uncontrolled study. The researchers’ conclusions neatly hedge the bets, suggesting that with recent trends in the direction of marijuana legalization, “physicians will increasingly encounter patients who use marijuana and should therefore be aware of the effects it can have on common disease processes, such as diabetes mellitus.” As it happens, the findings aren’t entirely new. Anecdotal reports abound. Back in 2010, on the Diabetes Daily support board, there was a long discussion of marijuana’s effect on blood glucose levels in diabetics. And there are several mouse models showing the same effects. In a prepared statement, lead investigator Murray A. Mittleman of Beth Israel Deaconess Medical Center in Boston conceded that previous epidemiological studies have found “lower prevalence rates of obesity and diabetes mellitus in marijuana users compared to people who have never used marijuana, suggesting a relationship between cannabinoids and peripheral metabolic processes.” However, he believes that “ours is the first study to investigate the relationship between marijuana use and fasting insulin, glucose, and insulin resistance.” Perhaps so. A 2011 study in the American Journal of Epidemiology concluded that “the prevalence of obesity is lower in cannabis users than in nonusers.” And the British Medical Journal featured a finding in 2012 by Los Angeles researchers that marijuana use was “independently associated with a lower prevalence of diabetes mellitus.” But the online patient guide for marijuana offered by Mayo Clinic says without equivocation that “cannabis may lower blood sugar. Caution is advised in patients with diabetes or hypoglycemia, and in those taking drugs, herbs, or supplements that affect blood sugar.” In fact, Mayo Clinic advises that patients may want to monitor their blood glucose levels if they smoke medical marijuana. Regarding the current study, the editor-in-chief of the American Journal of Medicine said in a statement that there is a need for “a great deal more basic and clinical research into the short- and long-term effects of marijuana in a variety of clinical settings such as cancer, diabetes, and frailty of the elderly.” Editor Joseph S. Alpert also called on the National Institutes of Health (NIH) and the Drug Enforcement Administration (DEA) to collaborate in “developing policies to implement solid scientific investigations that would lead to information assisting physicians in the proper use and prescription of THC in its synthetic or herbal form.” Penner E.A., Buettner H. & Mittleman M.A. (2013). The Impact of Marijuana Use on Glucose, Insulin, and Insulin Resistance among US Adults, The American Journal of Medicine, DOI: 10.1016/j.amjmed.2013.03.002 Photo Credit: http://www.herbalmission.org/...

Penner Elizabeth A., Buettner Hannah, & Mittleman Murray A. (2013) The Impact of Marijuana Use on Glucose, Insulin, and Insulin Resistance among US Adults. The American Journal of Medicine. DOI: 10.1016/j.amjmed.2013.03.002

RNA was able to do some complex tasks in the start of Life on Ancient Earth

2013-05-22T11:58:21Z

Main Point: Scientists have found that the complex biochemical changes through RNA may have been occurred in the start of the life on early Earth. Published in: Nature Chemistry Study Further: RNA (full form: ribonucleic acid) is a nucleic acid that has the sugar ribose, is found in all living cells, and is essential for the manufacture of proteins according to the instructions carried by genes. RNA also acts instead of DNA as the genetic material in certain viruses. RNA is thought to play an important role in the start of life on Earth more than 3 billion years ago, when environment had less oxygen and a huge amount of soluble iron, and the complex biochemical transformations were thought to be rare. Researchers worked on the 23S ribosomal RNA and transfer RNA, two most important and plentiful types of RNA, and found their ability to catalyze electron transfer in the presence of iron and lack of oxygen. “Our study shows that when RNA teams up with iron in an oxygen-free environment, RNA displays the powerful ability to catalyze single electron transfer, a process involved in the most sophisticated biochemistry, yet previously uncharacterized for RNA,” said Loren Williams, a professor in the School of Chemistry and Biochemistry at the Georgia Institute of Technology. Based on these findings researchers noted that RNA may have some yet-to-be-discovered abilities in the living beings on ancient Earth. “Our findings suggest that the catalytic competence of RNA may have been greater in early Earth conditions than in present conditions, and our experiments may have revived a latent function of RNA,” added Williams, who is also director of the Ribo Evo Center. Source: Astrobiology Magazine Reference: Hsiao, C., Chou, I., Okafor, C., Bowman, J., O'Neill, E., Athavale, S., Petrov, A., Hud, N., Wartell, R., Harvey, S., & Williams, L. (2013). RNA with iron(II) as a cofactor catalyses electron transfer Nature Chemistry, 5 (6), 525-528 DOI: 10.1038/nchem.1649...

Hsiao, C., Chou, I., Okafor, C., Bowman, J., O'Neill, E., Athavale, S., Petrov, A., Hud, N., Wartell, R., Harvey, S.... (2013) RNA with iron(II) as a cofactor catalyses electron transfer. Nature Chemistry, 5(6), 525-528. DOI: 10.1038/nchem.1649

Video Tip of the Week: Canary Database for sentinels of human health

2013-05-22T09:32:39Z

Recently we attended the Medical Library Association conference (#MLAnet13). Librarians are working so hard to wrangle information into usable forms, and to generate new connections among data types to reveal new information and leads for further studies. I ♥ librarians. In one of the sessions I attended on Medical Informatics, I heard several great talks. One [...]...

Rabinowitz, P., Scotch, M., & Conti, L. (2010) Animals as Sentinels: Using Comparative Medicine To Move Beyond the Laboratory. ILAR Journal, 51(3), 262-267. DOI: 10.1093/ilar.51.3.262

Rabinowitz, P., Gordon, Z., Holmes, R., Taylor, B., Wilcox, M., Chudnov, D., Nadkarni, P., & Dein, F. (2005) Animals as Sentinels of Human Environmental Health Hazards: An Evidence-Based Analysis. EcoHealth, 2(1), 26-37. DOI: 10.1007/s10393-004-0151-1

Rabinowitz, P., Cullen, M., & Lake, H. (1999) Wildlife as sentinels for human health hazards: a review of study designs. Journal of Environmental Medicine, 1(4), 217-223. DOI: 10.1002/jem.33

I Know Why She Swallowed The Fly

2013-05-22T08:15:00Z

It’s no secret that carnivorous plants are just way cool. Yet despite all the attention, there is still a lot we don’t know about them. Recent studies have expanded the view we have of these plants so that we now recognize more and more of them – like tomatoes and potatoes. Yes, our vegetables are insectivores! New research has show that pitcher plants possess anti-microbial peptides in their pitchers, that some sundews can catapult insects into their traps in just a few milliseconds, and that underwater carnivorous plants use a vacuum-packed trap door to suck prey into a trap. Or how about that pitcher plant that hopes a tree shrew will use it for a toilet?! ...

Poppinga, S., Hartmeyer, S., Seidel, R., Masselter, T., Hartmeyer, I., & Speck, T. (2012) Catapulting Tentacles in a Sticky Carnivorous Plant. PLoS ONE, 7(9). DOI: 10.1371/journal.pone.0045735

Buch, F., Rott, M., Rottloff, S., Paetz, C., Hilke, I., Raessler, M., & Mithofer, A. (2012) Secreted pitfall-trap fluid of carnivorous Nepenthes plants is unsuitable for microbial growth. Annals of Botany, 111(3), 375-383. DOI: 10.1093/aob/mcs287

Schulze, W., Sanggaard, K., Kreuzer, I., Knudsen, A., Bemm, F., Thogersen, I., Brautigam, A., Thomsen, L., Schliesky, S., Dyrlund, T.... (2012) The Protein Composition of the Digestive Fluid from the Venus Flytrap Sheds Light on Prey Digestion Mechanisms. Molecular , 11(11), 1306-1319. DOI: 10.1074/mcp.M112.021006

Down in the underground, scuds lose eyes but keep genes

2013-05-22T08:00:00Z

When animals live caves full time, their descendents often lose their eyes. It has happened over and over and over and over again, in all different kinds of animals. But how this happens is not obvious. Stephen Jay Gould wrote that some people would use cave fish as an argument that “Lamarck must have been on to something” with his idea that acquired characteristics can be inherited. Well, no, that’s not that case, but it is a good example of how tricky thinking about losses can be. The latest paper to try to sort out eye loss uses small amphipod crustaceans (Gammarus minus). An advantage of working with this particular species is that some populations live out in the sunshine with us, but several populations have gone down in the underground. In this case, Carlini and colleagues have three separate populations that went into caves, and they have their closest relatives, which are not cave dwellers. Each pair of populations acts as a natural experiment. The eyes do change with the habita, as expected. The amphipods that live “above” in springs have eyes with about 40 facets (ommatidia), while the cave dwellers’eyes have about 5 ommatidia. Using genetic tests, the team found that the genes for making visual pigments, the opsins, were still intact. They had not turned into non-working genes (“pseudogenes”). The genes for the opsins were extremely similar, and in no way as different as the eyes of these little guys were. What they did find was that the expression of these genes was dialed way down compared to their surface dwelling relatives: Carlini and colleagues note that this could be related to the overall reduction of the eye, but they attempted to control for this by scaling expression to the size of the eyes. Carlini and colleagues suggest that the opsin genes are under some sort of pressure to stay “intact” in this species (contrary to suggestion here that there is an advantage to blindness in caves). But the team doesn’t have a suggestion for what the opsin genes might be needed for, although they suggest it might be a non-visual function. This doesn’t solve the matter of how the animals are reducing the amount of opsins they make. Presumably there is some mutation in a regulatory gene, perhaps even a gene one specific to the visual system. They should keep an eye out for that. Reference Carlini DB, Satish S, Fong DW. 2013. Parallel reduction in expression, but no loss of functional constraint, in two opsin paralogs within cave populations of Gammarus minus (Crustacea: Amphipoda). BMC Evolutionary Biology 13(1): 89. DOI: 10.1186/1471-2148-13-89 Related posts “What big eyes you have!” Turning light and going blind: A tale of caves and genes Once more into the cave Better off blind Picture from here....

Carlini David B, Satish Suma, & Fong Daniel W. (2013) Parallel reduction in expression, but no loss of functional constraint, in two opsin paralogs within cave populations of Gammarus minus (Crustacea: Amphipoda). BMC Evolutionary Biology, 13(1), 89. DOI: 10.1186/1471-2148-13-89

Study Finds Why Penguins Lost Their Ability to Fly

2013-05-22T07:07:51Z

If you’ve seen March of the Penguins, you probably understand the question. Many penguins live a shitty life, walking miles and miles without any food and spending months apart from their families. This would be over with if they just flew from one place to the other. So why did they stop doing that?...

Elliott, K., Ricklefs, R., Gaston, A., Hatch, S., Speakman, J., & Davoren, G. (2013) High flight costs, but low dive costs, in auks support the biomechanical hypothesis for flightlessness in penguins. Proceedings of the National Academy of Sciences. DOI: 10.1073/pnas.1304838110

Double vision

2013-05-22T06:28:46Z

Scientists must ensure that they take the lead in the ethical debate surrounding the therapeutic use of stem cells derived from human clones....

Nature Editorial. (2013) Double vision. Nature, 497(7450), 409-409. DOI: 10.1038/497409a

Bacterium excluded from the Eukaryote Club

2013-05-22T04:43:08Z

It’s something you learn in high school – there are two basic approaches to cellular life – prokaryotes (bacteria and archaea) and eukaryotes (the rest of us – aardvarks, amoebae, apricots, etc.). Prokaryotes have an open-plan office, with all biological …...

Santarella-Mellwig, R., Pruggnaller, S., Roos, N., Mattaj, I., & Devos, D. (2013) Three-Dimensional Reconstruction of Bacteria with a Complex Endomembrane System. PLoS Biology, 11(5). DOI: 10.1371/journal.pbio.1001565

May 21, 2013

2013-05-21T21:53:01Z

“LET THERE BE LIGHT!” said the microscopist. Light plays a crucial role in microscopy and cell biology, and a recent paper describes the use of light to understand protein secretion.Light is used in microscopy in countless ways—to illuminate a sample, excite a fluorophore, and signal the localization or dynamics of a protein. Light can also be used to manipulate cellular events through the use of “caged” compounds that become active after illumination by certain wavelengths of light. This technology gives biologists the ability to spatially and temporally control cellular events in order to understand them better. Recent advances in this technology use illumination of plant photoreceptors to control protein-protein interactions, but some cellular processes such as protein secretion have been difficult to manipulate. A recent paper describes the use of the plant photoreceptor UVR8 in the first light-triggered protein secretion system developed. Chen and colleagues have shown that the recently described UVR8 can conditionally sequester proteins bound for secretion in the ER, and then upon illumination with UV light releases these proteins to the plasma membrane. In the images above, a neuron before (left) and after (right) UV illumination with this UVR8 system shows the movement of proteins known to be secreted from the soma and dendritic processes (arrowheads), where the ER is distributed, and into the Golgi (arrow), a necessary step in protein secretion.Chen, D., Gibson, E., & Kennedy, M. (2013). A light-triggered protein secretion system originally published in the Journal of Cell Biology, 201 (4), 631-640 DOI: 10.1083/jcb.201210119...

Chen, D., Gibson, E., & Kennedy, M. (2013) A light-triggered protein secretion system. originally published in the Journal of Cell Biology, 201(4), 631-640. DOI: 10.1083/jcb.201210119