Testosterone regulates solo song of tropical birds

Experiment in females uncovers male hormonal mechanism

In male songbirds of the temperate zone, the concentration of sex hormones is rising in spring, which leads to an increase in song activity during the breeding season. In the tropics, there has been little evidence so far about such a clear relationship between hormonal action and behaviour, which is partly due to a lower degree of seasonal changes of the environment. Researchers of the Max Planck Institute for Ornithology in Seewiesen have now discovered that in duetting African white-browed sparrow weavers, the solo song of dominant males is linked to elevated levels of testosterone. What is more, the male-typical solo song could be activated via testosterone treatment in female birds. The study thus shows a complex relationship between song behaviour and hormone concentration also in a tropical bird species.

'Tree of life' constructed for all living bird species

Scientists have mapped the evolutionary relationships among all 9,993 of the world’s known living bird species. The study, published today in Nature, is an ambitious project that uses DNA-sequence data to create a phylogenetic tree — a branching map of evolutionary relationships among species — that also links global bird speciation rates across space and time.

“This is the first dated tree of life for a class of species this size to be put on a global map,” says study co-author Walter Jetz, an evolutionary biologist at Yale University in New Haven, Connecticut.

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UC Santa Barbara Scientists Learn How to Unlock the Destiny of a Cell: A Gift for the Tin Man?

Scientists have discovered that breaking a biological signaling system in an embryo allows them to change the destiny of a cell. The findings could lead to new ways of making replacement organs.

The discovery was made in the laboratory of Joel H. Rothman, a professor in the Department of Molecular, Cellular, and Developmental Biology at UC Santa Barbara. The studies were reported in the interdisciplinary journal Genes and Development, and were carried out by Ph.D student Nareg Djabrayan, in collaboration with Rothman and two other members of the laboratory, Ph.D student Erica Sommermann and postdoctoral fellow Nathaniel Dudley.

"At some point along the way toward becoming part of a complete individual, cells become destined to choose a particular identity and long-term profession," Rothman noted. "Once a cell chooses who it will be, it locks onto that identity for the remainder of its life."

A cell that is destined to become a heart cell functions exclusively in the heart until it dies, and never chooses later to change jobs by becoming, for example, a brain cell. “If Oz’s wizard possessed the powers he claimed, and had a spare brain lying around, he could switch it to a heart as a gift for the Tin Man. And he could reverse the trick for the Scarecrow,” Rothman said.

Similarly, the researchers have found a way to unlock cells’ destinies and lead them to take on a new profession.

Biology and ideology: The anatomy of politics

An increasing number of studies suggest that biology can exert a significant influence on political beliefs and behaviours. Biological factors including genes, hormone levels and neurotransmitter systems may partly shape people’s attitudes on political issues such as welfare, immigration, same-sex marriage and war. And shrewd politicians might be able to take advantage of those biological levers through clever advertisements aimed at voters’ primal emotions.

Many of the studies linking biology to politics remain controversial and unreplicated. But the overall body of evidence is growing and might alter how people think about their own and others’ political attitudes.

“People are proud of their political beliefs,” says John Hibbing, a political scientist at the University of Nebraska–Lincoln. “We tend to think they’re the result of some rational responses to the world around us.” But in fact, a combination of genes and early experiences may predispose people to perceive and respond to political issues in certain ways. Recognizing that could help the public and politicians to develop more respect for those with opposing viewpoints.

Evolution is actually pretty predictable

“Is evolution predictable? To a surprising extent the answer is ‘yes’,” says Princeton professor Peter Andolfatto.

New research by Andolfatto and colleagues published in the journal Science suggests that knowledge of a species’ genes—and how certain external conditions affect the proteins encoded by those genes—could be used to determine a predictable evolutionary pattern driven by outside factors.

Scientists could then pinpoint how the diversity of adaptations seen in the natural world developed even in distantly related animals.

The researchers carried out a survey of DNA sequences from 29 distantly related insect species, the largest sample of organisms yet examined for a single evolutionary trait. Fourteen of these species have evolved a nearly identical characteristic due to one external influence—they feed on plants that produce cardenolides, a class of steroid-like cardiotoxins that are a natural defense for plants such as milkweed and dogbane.

Though separated by 300 million years of evolution, these diverse insects—which include beetles, butterflies, and aphids—experienced changes to a key protein called sodium-potassium adenosine triphosphatase, or the sodium-potassium pump, which regulates a cell’s crucial sodium-to-potassium ratio.

Did bacteria spark evolution of multicellular life?

Bacteria have a bad rap as agents of disease, but scientists are increasingly discovering their many benefits, such as maintaining a healthy gut.

A new study now suggests that bacteria may also have helped kick off one of the key events in evolution: the leap from one-celled organisms to many-celled organisms, a development that eventually led to all animals, including humans.

Published this month in the inaugural edition of the new online journal eLife, the study by University of California, Berkeley, and Harvard Medical School scientists involves choanoflagellates (aka “choanos”), the closest living relatives of animals. These microscopic, one-celled organisms sport a long tail or flagellum, tentacles for grabbing food and are members of the ocean’s plankton community. As our closest living relative, choanos offer critical insights into the biology of their last common ancestor with animals, a unicellular or colonial organism that lived and died over 650 million years ago.

“Choanoflagellates evolved not long before the origin of animals and may help reveal how animals first evolved,” said senior author Nicole King, UC Berkeley associate professor of molecular and cell biology.

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University of Toronto study demonstrates impact of adversity on early life development

It is time to put the nature versus nurture debate to rest and embrace growing evidence that it is the interaction between biology and environment in early life that influences human development, according to a series of studies recently published in a special edition of the Proceedings of the National Academy of Sciences (PNAS).

"Biologists used to think that our differences are pre-programmed in our genes, while psychologists argued that babies are born with a blank slate and their experience writes on it to shape them into the adults they become. Instead, the important question to be asking is, ‘How is our experience in early life getting embedded in our biology?’" says University of Toronto behavioural geneticist Marla Sokolowski. She is co-editor of the PNAS special edition titled "Biological Embedding of Early Social Adversity: From Fruit Flies to Kindergarteners" along with professors Tom Boyce (University of British Columbia) and Gene Robinson (University of Illinois).

Sokolowski, who is a University Professor in the Department of Ecology & Evolutionary Biology (EEB), the inaugural academic director of Uof T’s Fraser Mustard Institute for Human Development and co-director of the Experience-based Brain and Biological Development Program (EBBD) at the Canadian Institute for Advanced Research (CIFAR) says that relatively little is known about the gene-environment interplay that underlies the impact of early life adversity on adult health and behaviour.

In one of the studies in the series, Sokolowski and her colleagues found that chronic food deprivation and lack of adequate nutrition in the early life of the fruit fly Drosophila melanogaster had significant impact on adult behaviour and quality of life. Fruit flies are especially useful for genetic studies because they share a surprising number of qualities with humans, are inexpensive to care for and reproduce rapidly, allowing for several generations to be studied in just a few months.

BeerSci: What Beer’s Key Ingredient Reveals About Our Own Genomes

The yeast S. cerevisiae is instrumental in brewing ale. But did you know that it’s also instrumental in helping scientists better understand cells?

Humans have been exploiting S. cerevisiae's fermentation prowess for thousands of years. Without it we wouldn't have beer, bread or wine. In addition to its uses in food production, S. cerevisiae is also an amazing tool for molecular and cell biology, one that is helping scientists suss out the rules of how our cells work and gain clues to what happens at the molecular level when things go wrong.

That’s because S. cerevisiae is one of the simplest eukaryotic cells—cells like those that make up your dog, your houseplants or your local bartender. In fact, in 1996 S. cerevisiae became the first eukaryote to have its genome sequenced. According to the Saccharomyces Genome Database, S. cerevisiae's genome has some 12,100,000 base pairs and some 6,600 open reading frames (that is, places in the genome that could possibly contain a gene).

Most of you, I am sure, remember that there are two general kinds of cells: prokaryotic and eukaryotic. That is, “no nucleus” and “has a nucleus.” That’s all true, but the differences between the two kinds of cells are much more profound than that. Bacteria — prokaryotes — organize their genetic material in a completely different (and much simpler) way than do eukaryotes. Prokaryotes usually only have a chunk of DNA for a genome — usually circular — and a few extra chunks, called plasmids, kicking around in the cytosol. Those plasmids are really useful in doing things like sharing genes between bacteria, and its how one antibiotic-resistant strain of bacteria can pass along antibiotic resistance to a bunch of nigh-unrelated strains of bacteria in, say, your intestines. The genes in bacteria are generally read exactly as they are found in the DNA, kind of like how you’re reading this sentence. No intervening clumps of letters to clutter things up.

Eukaryotes, on the other hand, bundle up all that DNA (and they have a lot of it) into a protein-DNA complex called chromatin, then wind that chromatin into individual chromosomes. Further, the genes are constructed in such a way that they must be heavily processed before they can ever “code” for a functional protein. Much of what we understand about eukaryotic cellular processes and eukaryotic gene expression, we learned by studying the molecular mechanics of S. cerevisiae.

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Cell Mechanism Findings Could One Day be Used to Engineer Organs

Biologists have teamed up with mechanical engineers from the The University of Texas at Dallas to conduct cell research that provides information that may one day be used to engineer organs.

The research, published online in the Proceedings of the National Academy of Sciences, sheds light on the mechanics of cell, tissue and organ formation. The research revealed basic mechanisms about how a group of bacterial cells can form large three-dimensional structures.

“If you want to create an organism, the geometry of how a group of cells self-organizes is crucial,” said Dr. Hongbing Lu, professor of mechanical engineering and holder of the Louis Beecherl Jr. Chair at UT Dallas and an author of the study. “We found that cell death leads to wrinkles, and the stiffer the cell the fewer wrinkles.”

Organ formation is the result of individual cells teaming with others. The aggregate of the cells and their environment form a thin layer of what is known as a biofilm. These biofilms form 3-D wrinkled patterns.

Why stem-cell science thrives in Japan

It’s easy to take for granted the epic scale of what some scientists are attempting these days. When the news broke a couple of weeks ago that Japanese scientists had turned normal cells from a mouse into eggs, and then fertilized them and seen them develop into baby mice, I thought it was pretty cool.

But I wasn’t that surprised.

I knew that Katsuhiko Hayashi — one of the scientists involved — was doing fascinating research on stem cells at Kyoto University, and so this seemed a natural progression for his work to take.

Then I spoke to him and his boss. What they said reminded me that they are attempting to do something that, until recently, would have blown the mind of almost any scientist, philosopher or other kind of intellectual there’s ever been throughout the whole of human history.

Mitinori Saitou, who is head of Hayashi’s lab at the Department of Anatomy and Cell Biology in the Graduate School of Medicine, was highly ambitious from an early age, and became particularly focused when he was doing his PhD as a young man.

"I got interested in germ-cell biology and the regulation of the cell fates," he told me, "hoping that one day it may be possible to develop a methodology to control cellular fate at will."

To control fate: It’s like something out of a Greek myth.

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