A Blog Around The Clock

Good Sexual Intercourse Lasts Minutes, Not Hours, Therapists Say:

Satisfactory sexual intercourse for couples lasts from 3 to 13 minutes, contrary to popular fantasy about the need for hours of sexual activity, according to a survey of U.S. and Canadian sex therapists.

Mouse Calls During Courtship Help Search For Emotion-controlling Genes:

Scientists have long known that emotions and other personality traits and disorders run together in families. But finding which genes are most important in controlling emotions has proven difficult. Humans and mice have similar numbers of genes, but mice are valuable because their genes can be deleted or added. Many researchers have begun to study mouse behaviors to try to link genes with complex behaviors. A new study found that male mice make high-frequency vocalizations during sexual interactions with female mice. These high-frequency calls are associated with approach behaviours, and with genes that control positive emotions.

The Untrained Eye: Confusing Sexual Interest With Friendliness:

New research from Indiana University and Yale suggests that college-age men confuse friendly non-verbal cues with cues for sexual interest because the men have a less discerning eye than women — but their female peers aren’t far behind.

The Lean Gene: Thinness Is An Inheritable Trait:

Your friend can eat whatever she wants and still fit into her prom dress, but you gain five pounds if you just look at that chocolate cake. Before you sign up for Weight Watchers and that gym membership, though, you may want to look at some recent research from Tel Aviv University and save yourself a few hundred dollars.

More under the fold:

Continue reading →

There are 47 articles published in PLoS ONE this week. Here are some of the coolest titles – you go and find your own.
Ultrasonic Vocalizations Induced by Sex and Amphetamine in M2, M4, M5 Muscarinic and D2 Dopamine Receptor Knockout Mice:

Adult mice communicate by emitting ultrasonic vocalizations (USVs) during the appetitive phases of sexual behavior. However, little is known about the genes important in controlling call production. Here, we study the induction and regulation of USVs in muscarinic and dopaminergic receptor knockout (KO) mice as well as wild-type controls during sexual behavior. Female mouse urine, but not female rat or human urine, induced USVs in male mice, whereas male urine did not induce USVs in females. Direct contact of males with females is required for eliciting high level of USVs in males. USVs (25 to120 kHz) were emitted only by males, suggesting positive state; however human-audible squeaks were produced only by females, implying negative state during male-female pairing. USVs were divided into flat and frequency-modulated calls. Male USVs often changed from continuous to broken frequency-modulated calls after initiation of mounting. In M2 KO mice, USVs were lost in about 70-80% of the mice, correlating with a loss of sexual interaction. In M5 KO mice, mean USVs were reduced by almost 80% even though sexual interaction was vigorous. In D2 KOs, the duration of USVs was extended by 20%. In M4 KOs, no significant differences were observed. Amphetamine dose-dependently induced USVs in wild-type males (most at 0.5 mg/kg i.p.), but did not elicit USVs in M5 KO or female mice. These studies suggest that M2 and M5 muscarinic receptors are needed for male USV production during male-female interactions, likely via their roles in dopamine activation. These findings are important for the understanding of the neural substrates for positive affect.

Maternal Cocaine Administration in Mice Alters DNA Methylation and Gene Expression in Hippocampal Neurons of Neonatal and Prepubertal Offspring:

Previous studies documented significant behavioral changes in the offspring of cocaine-exposed mothers. We now explore the hypothesis that maternal cocaine exposure could alter the fetal epigenetic machinery sufficiently to cause lasting neurochemical and functional changes in the offspring. Pregnant CD1 mice were administered either saline or 20 mg/kg cocaine twice daily on gestational days 8-19. Male pups from each of ten litters of the cocaine and control groups were analyzed at 3 (P3) or 30 (P30) days postnatum. Global DNA methylation, methylated DNA immunoprecipitation followed by CGI2 microarray profiling and bisulfite sequencing, as well as quantitative real-time RT-PCR gene expression analysis, were evaluated in hippocampal pyramidal neurons excised by laser capture microdissection. Following maternal cocaine exposure, global DNA methylation was significantly decreased at P3 and increased at P30. Among the 492 CGIs whose methylation was significantly altered by cocaine at P3, 34% were hypermethylated while 66% were hypomethylated. Several of these CGIs contained promoter regions for genes implicated in crucial cellular functions. Endogenous expression of selected genes linked to the abnormally methylated CGIs was correspondingly decreased or increased by as much as 4-19-fold. By P30, some of the cocaine-associated effects at P3 endured, reversed to opposite directions, or disappeared. Further, additional sets of abnormally methylated targets emerged at P30 that were not observed at P3. Taken together, these observations indicate that maternal cocaine exposure during the second and third trimesters of gestation could produce potentially profound structural and functional modifications in the epigenomic programs of neonatal and prepubertal mice.

Ecological Niche Dimensionality and the Evolutionary Diversification of Stick Insects:

The degree of phenotypic divergence and reproductive isolation between taxon pairs can vary quantitatively, and often increases as evolutionary divergence proceeds through various stages, from polymorphism to population differentiation, ecotype and race formation, speciation, and post-speciational divergence. Although divergent natural selection promotes divergence, it does not always result in strong differentiation. For example, divergent selection can fail to complete speciation, and distinct species pairs sometimes collapse (‘speciation in reverse’). Widely-discussed explanations for this variability concern genetic architecture, and the geographic arrangement of populations. A less-explored possibility is that the degree of phenotypic and reproductive divergence between taxon pairs is positively related to the number of ecological niche dimensions (i.e., traits) subject to divergent selection. Some data supporting this idea stem from laboratory experimental evolution studies using Drosophila, but tests from nature are lacking. Here we report results from manipulative field experiments in natural populations of herbivorous Timema stick insects that are consistent with this ‘niche dimensionality’ hypothesis. In such insects, divergent selection between host plants might occur for cryptic colouration (camouflage to evade visual predation), physiology (to detoxify plant chemicals), or both of these niche dimensions. We show that divergent selection on the single niche dimension of cryptic colouration can result in ecotype formation and intermediate levels of phenotypic and reproductive divergence between populations feeding on different hosts. However, greater divergence between a species pair involved divergent selection on both niche dimensions. Although further replication of the trends reported here is required, the results suggest that dimensionality of selection may complement genetic and geographic explanations for the degree of diversification in nature.

Mesoscopic Structure Conditions the Emergence of Cooperation on Social Networks:

We study the evolutionary Prisoner’s Dilemma on two social networks substrates obtained from actual relational data. We find very different cooperation levels on each of them that cannot be easily understood in terms of global statistical properties of both networks. We claim that the result can be understood at the mesoscopic scale, by studying the community structure of the networks. We explain the dependence of the cooperation level on the temptation parameter in terms of the internal structure of the communities and their interconnections. We then test our results on community-structured, specifically designed artificial networks, finding a good agreement with the observations in both real substrates. Our results support the conclusion that studies of evolutionary games on model networks and their interpretation in terms of global properties may not be sufficient to study specific, real social systems. Further, the study allows us to define new quantitative parameters that summarize the mesoscopic structure of any network. In addition, the community perspective may be helpful to interpret the origin and behavior of existing networks as well as to design structures that show resilient cooperative behavior.

The Airborne Metagenome in an Indoor Urban Environment:

The indoor atmosphere is an ecological unit that impacts on public health. To investigate the composition of organisms in this space, we applied culture-independent approaches to microbes harvested from the air of two densely populated urban buildings, from which we analyzed 80 megabases genomic DNA sequence and 6000 16S rDNA clones. The air microbiota is primarily bacteria, including potential opportunistic pathogens commonly isolated from human-inhabited environments such as hospitals, but none of the data contain matches to virulent pathogens or bioterror agents. Comparison of air samples with each other and nearby environments suggested that the indoor air microbes are not random transients from surrounding outdoor environments, but rather originate from indoor niches. Sequence annotation by gene function revealed specific adaptive capabilities enriched in the air environment, including genes potentially involved in resistance to desiccation and oxidative damage. This baseline index of air microbiota will be valuable for improving designs of surveillance for natural or man-made release of virulent pathogens.

Inevitable Evolutionary Temporal Elements in Neural Processing: A Study Based on Evolutionary Simulations:

Recent studies have suggested that some neural computational mechanisms are based on the fine temporal structure of spiking activity. However, less effort has been devoted to investigating the evolutionary aspects of such mechanisms. In this paper we explore the issue of temporal neural computation from an evolutionary point of view, using a genetic simulation of the evolutionary development of neural systems. We evolve neural systems in an environment with selective pressure based on mate finding, and examine the temporal aspects of the evolved systems. In repeating evolutionary sessions, there was a significant increase during evolution in the mutual information between the evolved agent’s temporal neural representation and the external environment. In ten different simulated evolutionary sessions, there was an increased effect of time -related neural ablations on the agents’ fitness. These results suggest that in some fitness landscapes the emergence of temporal elements in neural computation is almost inevitable. Future research using similar evolutionary simulations may shed new light on various biological mechanisms.

Climate Change And Human Hunting Combine To Drive The Woolly Mammoth Extinct:

Does the human species have mammoth blood on its hands? Scientists have long debated the relative importance of hunting by our ancestors and change in global climate in consigning the mammoth to the history books. A new paper uses climate models and fossil distribution to establish that the woolly mammoth went extinct primarily because of loss of habitat due to changes in temperature, while human hunting acted as the final straw.

Anne-Marie, Kambiz and artificialhabitat have more.
Study Questions ‘Cost Of Complexity’ In Evolution

Higher organisms do not have a “cost of complexity” — or slowdown in the evolution of complex traits — according to a report by researchers at Yale and Washington University in Nature. Biologists have long puzzled over the relationship between evolution of complex traits and the randomness of mutations in genes. Some have proposed that a “cost of complexity” makes it more difficult to evolve a complicated trait by random mutations, because effects of beneficial mutations are diluted.

More under the fold….

Continue reading →

Climate Change, Humans, and the Extinction of the Woolly Mammoth:

What caused the woolly mammoth’s extinction? Climate warming in the Holocene might have driven the extinction of this cold-adapted species, yet the species had survived previous warming periods, suggesting that the more-plausible cause was human expansion. Testing these competing hypotheses has been hampered by the difficulty in generating quantitative estimates of the relationship between the mammoth’s contraction and the climatic and/or human-induced drivers of extinction. In this study, we combined paleo-climate simulations, climate envelope models (which describe the climate associated with the known distribution of a species–its envelope–and estimate that envelope’s position under different climate change scenarios), and a population model that includes an explicit treatment of woolly mammoth-human interactions to measure the extent to which climate changes, increased human pressures, or a combination of both factors might have been responsible. Results show a dramatic decline in suitable climate conditions for the mammoth between the Late Pleistocene and the Holocene, with hospitable areas in the mid-Holocene being restricted mainly to Arctic Siberia, where the latest records of woolly mammoths in continental Asia have been found. The population model results also support the view that the collapse of the climatically suitable area caused a significant drop in mammoth population size, making the animals more vulnerable to increasing hunting pressure from expanding human populations. The coincidence of the collapse of climatically suitable areas and the increase in anthropogenic impacts in the Holocene are most likely to have been the “coup de grâce,” which set the place and time for the extinction of the woolly mammoth.

What Killed the Woolly Mammoth?:

Forty-two thousand years ago, during the last glacial advance of the Pleistocene epoch, woolly mammoths thundered across the frozen steppes of the Eurasian continent. The huge beasts thrived on the arid tundra of the last ice age, having adapted to temperatures that would chill the toes off any hairless ape. Yet, by the middle of the Holocene epoch, 6,000 years ago, the glaciers had retreated and the Eurasian woolly mammoth was on the verge of extinction. They were ultimately done in, say David Nogués-Bravo and colleagues, by climate change–with a helping hand from humans.

Exposure to War as a Risk Factor for Mental Disorders:

While large-scale national psychiatric epidemiologic studies have been conducted in Western industrialized nations [1-3], studies in the Arab world have generally been limited to smaller populations [4-6]. In addition, while exposure to war as a risk factor for the development of mental disorders in military populations has previously been described [7,8], the effect of war upon first onset of a range of mental disorders in civilian populations at a national level has not been explored.

Chile’s Neoliberal Health Reform: An Assessment and a Critique:

* The Chilean health system underwent a drastic neoliberal reform in the 1980s, with the creation of a dual system: public and private health insurance and public and private provision of health services.
* This reform served as a model for later World Bank-inspired reforms in countries like Colombia.
* The private part of the Chilean health system, including private insurers and private providers, is highly inefficient and has decreased solidarity between rich and poor, sick and healthy, and young and old.
* In spite of serious underfinancing during the Pinochet years, the public health component remains the backbone of the system and is responsible for the good health status of the Chilean population.
* The Chilean health reform has lessons for other countries in Latin America and elsewhere: privatisation of health insurance services may not have the expected results according to neoliberal doctrine. On the contrary, it may increase unfairness in financing and inequitable access to quality care.

Chromosomal Gene Movements Reflect the Recent Origin and Biology of Therian Sex Chromosomes:

Our sex chromosomes have profoundly differentiated since evolving from an ancestral pair of non-sex chromosomes (autosomes). In this study, we first show that X chromosome-derived retrogenes (genes that arose as duplicates of “parental” X-linked genes) are specifically expressed during the meiotic and postmeiotic stages of spermatogenesis, thus functionally replacing their parents during, but also after, the process of male meiotic sex chromosome inactivation (MSCI). We then show that the “export” of retroposed gene copies from the X chromosome started rather recently during mammalian evolution, on the eutherian (“placental” mammal) and marsupial lineages, respectively. This suggests that MSCI–the main driving force for this out of the X gene “movement”–originated around the separation of these two major (therian) mammalian lineages, approximately 180 million years ago. Given that MSCI was likely triggered as soon as the proto-X and -Y chromosomes ceased to recombine (an event that marks the origin of these sex chromosomes), our data also support the recent notion that our sex chromosomes and those of other therians emerged, not in the common ancestor of all mammals, but–probably rather late–in the therian ancestor.

Teenaged Dome-skulled Dinosaurs Could Really Knock Heads, Virtual Smash-ups Show:

After half a century of debate, a University of Alberta researcher has confirmed that dome-headed dinosaurs called pachycephalosaurs could collide with each other during courtship combat. Eric Snively, an Alberta Ingenuity fellow at the U of A, used computer software to smash the sheep-sized dinosaurs together in a virtual collision and results showed that their bony domes could emerge unscathed.

Squid Beak Is Both Hard And Soft, A Material That Engineers Want To Copy:

How did nature make the squid’s beak super hard and sharp —- allowing it, without harm to its soft body —- to capture its prey? The question has captivated those interested in creating new materials that mimic biological materials. The results are published in the journal Science.

Sensors For Bat-inspired Spy Plane Under Development:

A six-inch robotic spy plane modeled after a bat would gather data from sights, sounds and smells in urban combat zones and transmit information back to a soldier in real time.

Hormone That Controls Hunger And Appetite Also Linked To Reduced Fertility:

Researchers at Yale School of Medicine have found that in-utero exposure to the hormone grhelin, a molecule that controls appetite and hunger and nutrition, can result in decreased fertility and fewer offspring. Ghrelin, the so-called “hunger hormone,” is produced in the stomach and brain, induces food intake, and operates through a brain region that controls cravings for food and other energy sources. Ghrelin decreases the HOXA 10 gene that is involved in developmental programming of the uterus. The HOXA 10 gene determines how the uterus will develop in adulthood.

Small Desert Beetle Found To Engineer Ecosystems:

The catastrophic action a tiny beetle is wreaking on the deteriorating Chihuahuan desert will be revealed in the April edition of the Royal Entomological Society’s Ecological Entomology journal.

Armed Beetles Find A Mate, Whatever Their Size:

One species of armed beetle is proving that size doesn’t necessarily matter when it comes to finding a mate. The creature uses what might be considered rather persuasive ‘pulling techniques.’

American West Heating Nearly Twice As Fast As Rest Of World, New Analysis Shows:

The American West is heating up more rapidly than the rest of the world, according to a new analysis of the most recent federal government temperature figures. The news is especially bad for some of the nation’s fastest growing cities, which receive water from the drought-stricken Colorado River. The average temperature rise in the Southwest’s largest river basin was more than double the average global increase, likely spelling even more parched conditions.

Are You What You Eat? New Study Of Body Weight Change Says Maybe Not:

If identical twins eat and exercise equally, must they have the same body weight” By analyzing the fundamental equations of body weight change, NIH investigators Carson Chow and Kevin Hall find that identical twins with identical lifestyles can have different body weights and different amounts of body fat.

Appendix Removed Through Vagina: U.S. First:

On March 26, 2008, surgeons at UC San Diego Medical Center removed an inflamed appendix through a patient’s vagina, a first in the United States. Following the 50-minute procedure, the patient, Diana Schlamadinger, reported only minor discomfort. Removal of diseased organs through the body’s natural openings offers patients a rapid recovery, minimal pain, and no scarring. Key to these surgical clinical trials is collaboration with medical device companies to develop new minimally-invasive tools.

Teenage Risk-taking: Teenage Brains Really Are Different From Child Or Adult Brains:

Many parents are convinced that the brains of their teenage offspring are different than those of children and adults. New data confirms that this is the case. An article by Jay N. Giedd, MD, of the National Institute of Mental Health (NIMH), published in Journal of Adolescent Health describes how brain changes in the adolescent brain impact cognition, emotion and behavior.

Who’s Bad? Chimps Figure It Out By Observation:

Chimpanzees make judgments about the actions and dispositions of strangers by observing others’ behavior and interactions in different situations. Specifically, chimpanzees show an ability to recognize certain behavioral traits and make assumptions about the presence or absence of these traits in strangers in similar situations thereafter. These findings are by Dr. Francys Subiaul – from the George Washington University in Washington DC – and his team.

Can You Rescue A Rainforest? The Answer May Be Yes:

Half a century after most of Costa Rica’s rainforests were cut down, researchers from the Boyce Thompson Institute took on a project that many thought was impossible – restoring a tropical rainforest ecosystem.

Cooperative Classrooms Lead To Better Friendships, Higher Achievement In Young Adolescents:

Students competing for resources in the classroom while discounting each others’ success are less likely to earn top grades than students who work together toward goals and share their success, according to an analysis of 80 years of research.

Despite Awareness Of Global Warming Americans Concerned More About Local Environment:

British Prime Minister Gordon Brown recently declared climate change a top international threat, and Al Gore urged politicians to get involved to fight global warming. Results from a recent survey conducted by a University of Missouri professor reveal that the U.S. public, while aware of the deteriorating global environment, is concerned predominantly with local and national environmental issues.

Systems Biology Approach Identifies Nutrient Regulation Of Biological Clock In Plants:

Using a systems biological analysis of genome-scale data from the model plant Arabidopsis, an international team of researchers identified that the master gene controlling the biological clock is sensitive to nutrient status. This hypothesis derived from multi-network analysis of Arabidopsis genomic data, and validated experimentally, has shed light on how nutrients affect the molecular networks controlling plant growth and development in response to nutrient sensing.

Weight Bias Is As Prevalent As Racial Discrimination, Study Suggests:

Discrimination against overweight people–particularly women–is as common as racial discrimination, according to a study by the Rudd Center for Food Policy & Obesity at Yale University.

Why Don’t Kids Walk To School Anymore?:

Maybe when we were their age, we walked five miles to school, rain or shine. So why don’t most children today walk or bike to school? It’s not necessarily because they’re spoiled, lazy or over scheduled. According to a University of Michigan researcher, concerns about safety are the main reason that less than 13 percent of U.S. children walked or biked to school in 2004, compared to more than 50 percent who did so in 1969.

Evolution Of New Species Slows Down As Number Of Competitors Increases:

The rate at which new species are formed in a group of closely related animals decreases as the total number of different species in that group goes up, according to new research. The research team believes these findings suggest that new species appear less and less as the number of species in a region approaches the maximum number that it can support.

Zoologists Unlock New Secrets About Frog Deaths:

New research from zoologists at Southern Illinois University Carbondale opens a bigger window to understanding a deadly fungus that is killing off frogs throughout Central and South America, and that could threaten amphibian populations in North America as well.

Heat Stress Model Keeps Cows Cool:

It’s hard to relax if your cattle are stressed, so the ability to predict and avoid potential stressors is essential. Fortunately, an online model developed by scientists with the Agricultural Research Service (ARS) provides information to help cattle–and producers–keep their cool when temperatures rise.

Scientists Learn What’s ‘Up’ With A Class Of Retinal Cells In Mice:

Harvard University researchers have discovered a new type of retinal cell that plays an exclusive and unusual role in mice: detecting upward motion. The cells reflect their function in the physical arrangement of their dendrites, branch-like structures on neuronal cells that form a communicative network with other dendrites and neurons in the brain.

Statistics Are Insufficient For Study Of Proteins’ Signal System: New Study Contradicts Previous Work:

Ten years ago great attention was attracted by the discovery that it was possible to demonstrate signal transfer in proteins using statistical methods. In an article in the journal Proceedings of the National Academy of Science Uppsala researchers are now presenting results of experiments that contradict the theory.

This week’s PLoS Computational Biology is chockful of interesting articles, including these:
Open Access: Taking Full Advantage of the Content:

This Journal and the Public Library of Science (PLoS) at large are standard bearers of the full potential offered through open access publication, but what of you, the reader? For most of you, open access may imply free access to read the journals, but nothing more. There is a far greater potential, but, up to now, little to point to that highlights its tangible benefits. We would argue that, as yet, the full promise of open access has not been realized. There are few persistent applications that collectively use the full on-line corpus, which for the biosciences at least is maintained in PubMed Central (http://www.pubmedcentral.nih.gov/). In short, there are no “killer apps.” Since this readership, beyond any other, would seem to have the ability to change this situation at least in the biosciences, we are issuing a call to action.

Modeling the Effects of Cell Cycle M-phase Transcriptional Inhibition on Circadian Oscillation:

Circadian clock and cell cycle are two important biological processes that are essential for nearly all eukaryotes. The circadian clock governs day and night 24 h periodic molecular processes and physiological behaviors, while cell cycle controls cell division process. It has been widely observed that cell division does not occur randomly across day and night, but instead is normally confined to specific times during day and night. These observations suggest that cell cycle events are gated by the circadian clock. Regarding the biological benefit and rationale for this intriguing gating phenomena, it has been postulated that circadian gating helps to maintain genome stability by confining radiation-sensitive cell cycle phases to night. Bearing in mind the facts that global transcriptional inhibition occurs at cell division and transcriptional inhibition shifts circadian phases and periods, we postulate that confining cell division to specific circadian times benefits the circadian clock by removing or minimizing the side effects of cell division on the circadian clock. Our results based on computational simulation in this study show that periodic transcriptional inhibition can perturb the circadian clock by altering circadian phases and periods, and the magnitude of the perturbation is clearly circadian phase dependent. Specifically, transcriptional inhibition initiated at certain circadian phases induced minimal perturbation to the circadian clock. These results provide support for our postulation. Our postulation and results point to the importance of the effect of cell division on the circadian clock in the interaction between circadian and cell cycle and suggest that it should be considered together with other factors in the exploitation of circadian cell cycle interaction, especially the phenomena of circadian gating of cell cycle.

The Evolution of Robust Development and Homeostasis in Artificial Organisms:

During development, multicellular animals are shaped by cell proliferation, cell rearrangement, and cell death to generate an adult whose form is maintained over time. Disruption of this finely balanced state can have devastating consequences, including aging, psoriasis, and cancer. Typically, however, development is robust, so that animals achieve the same final form even when challenged by environmental damage such as wounding. To see how morphogenetic robustness arises, we have taken an in silico approach to evolve digital organisms that exhibit distinct phases of growth and homeostasis. During the homeostasis period, organisms were found to use a variety of strategies to maintain their form. Remarkably, however, all recovered from severe wounds, despite having evolved in the absence of selection pressure to do so. This ability to regenerate was most striking in an organism with a tissue-like architecture, where it was enhanced by a directional flux of cells that drives tissue turnover. This identifies a stratified architecture, like that seen in human skin and gut, as an evolutionarily accessible and robust form of tissue organisation, and suggests that wound-healing may be a general feature of evolved morphogenetic systems. Both may therefore contribute to homeostasis, wound-healing, and regeneration in real animals.

Shaping Embodied Neural Networks for Adaptive Goal-directed Behavior:

The ability of a brain to learn has been studied at various levels. However, a large gap exists between behavioral studies of learning and memory and studies of cellular plasticity. In particular, much remains unknown about how cellular plasticity scales to affect network population dynamics. In previous studies, we have addressed this by growing mammalian brain cells in culture and creating a long-term, two-way interface between a cultured network and a robot or an artificial animal. Behavior and learning could now be observed in concert with the detailed and long-term electrophysiology. In this work, we used modeling/simulation of living cortical cultures to investigate the network’s capability to learn goal-directed behavior. A biologically inspired simulated network was used to determine an effective closed-loop training algorithm, and the system successfully exhibited multi-task goal-directed adaptive behavior. The results suggest that even though lacking the characteristic layered structure of a brain, the network still could be functionally shaped and showed meaningful behavior. Knowledge gained from working with such closed-loop systems could influence the design of future artificial neural networks, more effective neuroprosthetics, and even the use of living networks themselves as a biologically based control system.

The Dynamics of Human Body Weight Change:

Understanding the dynamics of human body weight change has important consequences for conditions such as obesity, starvation, and wasting syndromes. Changes of body weight are known to result from imbalances between the energy derived from food and the energy expended to maintain life and perform physical work. However, quantifying this relationship has proved difficult, in part because the body is composed of multiple components and weight change results from alterations of body composition (i.e., fat versus lean mass). Here, we show that mathematical modeling can provide a general description of how body weight will change over time by tracking the flux balances of the macronutrients fat, protein, and carbohydrates. For a fixed food intake rate and physical activity level, the body weight and composition will approach steady state. However, the steady state can correspond to a unique body weight or a continuum of body weights that are all consistent with the same food intake and energy expenditure rates. Interestingly, existing experimental data on human body weight dynamics cannot distinguish between these two possibilities. We propose experiments that could resolve this issue and use computer simulations to demonstrate how such experiments could be performed.

Reason For Almost Two Billion Year Delay In Animal Evolution On Earth Discovered:

Scientists from around the world have reconstructed changes in Earth’s ancient ocean chemistry during a broad sweep of geological time, from about 2.5 to 0.5 billion years ago. They have discovered that a deficiency of oxygen and the heavy metal molybdenum in the ancient deep ocean may have delayed the evolution of animal life on Earth for nearly 2 billion years.

Brain’s ‘Sixth Sense’ For Calories Discovered:

The brain can sense the calories in food, independent of the taste mechanism, researchers have found in studies with mice. Their finding that the brain’s reward system is switched on by this “sixth sense” machinery could have implications for understanding the causes of obesity. For example, the findings suggest why high-fructose corn syrup, widely used as a sweetener in foods, might contribute to obesity.

Common Aquatic Animals Show Extreme Resistance To Radiation:

Scientists at Harvard University have found that a common class of freshwater invertebrate animals called bdelloid rotifers are extraordinarily resistant to ionizing radiation, surviving and continuing to reproduce after doses of gamma radiation much greater than that tolerated by any other animal species studied to date.

Mantis Shrimp Vision Reveals New Way That Animals Can See:

Mantis shrimp can see the world in a way that had never been observed in any animal before, researchers report in the March 20th Current Biology, a Cell Press publication. The discovery–which marks the fourth type of visual system–suggests that the ability to perceive circular polarized light may lend mantis shrimp a secret mode of communication.

Elephants Without Borders: Scientists Track African Elephants By Satellite:

In many regions of Africa, elephants are frequent visitors to farms and villages as they roam the landscape searching for food and water. This often brings them into conflict with humans. Researchers at the University of Massachusetts Amherst are tracking their movements through southern and eastern Africa using satellite collars in an effort to understand their ecology and help prevent these conflicts.