study-shows-how-epigenetic-memory-is-passed-across-generations

Study Shows How Epigenetic Memory is Passed Across Generations

A growing body of evidence suggests that environmental stresses can cause changes in gene expression that are transmitted from parents to their offspring, making “epigenetics” a hot topic. Epigenetic modifications do not affect the DNA sequence of genes, but change how the DNA is packaged and how genes are expressed. Now, a study by scientists at UC Santa Cruz shows how epigenetic memory can be passed across generations and from cell to cell during development.

The study, published September 19 in Science, focused on one well studied epigenetic modification–the methylation of a DNA packaging protein called histone H3. Methylation of a particular amino acid (lysine 27) in histone H3 is known to turn off or “repress” genes, and this epigenetic mark is found in all multicellular animals, from humans to the tiny roundworm C. elegans that was used in this study. ”There has been ongoing debate about whether the methylation mark can be passed on through cell divisions and across generations, and we’ve now shown that it is,” said corresponding author Susan Strome, a professor of molecular, cell and developmental biology at UC Santa Cruz.

Strome noted that the findings in this study of transmission of histone methylation in C. elegans have important implications in other organisms, even though different organisms use the repressive marker that was studied to regulate different genes during different aspects of development. All animals use the same enzyme to create the same methylation mark as a signal for gene repression, and her colleagues who study epigenetics in mice and humans are excited about the new findings, Strome said.

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Why Do Chimps Kill Each Other?

War—what is it good for? “Absolutely nothing” according to the refrain of a 1970 hit song. Many humans would agree with this sentiment. But a major new study of warfare in chimpanzees finds that lethal aggression can be evolutionarily beneficial in that species, rewarding the winners with food, mates, and the opportunity to pass along their genes. The findings run contrary to recent claims that chimps fight only if they are stressed by the impact of nearby human activity—and could help explain the origins of human conflict as well.

Ever since primatologist Jane Goodall’s pioneering work at Gombe Stream National Park in Tanzania in the 1970s, researchers have been aware that male chimps often organize themselves into warring gangs that raid each other’s territory, sometimes leaving mutilated dead bodies on the battlefield. Primatologists have concluded that their territorial battles are evolutionarily adaptive. But some anthropologists have resisted this interpretation, insisting instead that today’s chimps are aggressive only because they are endangered by human impact on their natural environment. For example, when humans cut down forests for farming or other uses, the loss of habitat forces chimps to live in close proximity to one another and to other groups. Feeding chimps can also increase their population density by causing them to cluster around human camps, thus causing more competition between them.

The researchers created a series of computer models to test whether the observed killings could be better explained by adaptive strategies or human impacts. The models incorporated variables such as whether the animals had been fed by humans, the size of their territory (smaller territories presumably corresponding to greater human encroachment), and other indicators of human disturbance, all of which were assumed to be related to human impacts; and variables such as the geographic location of the animals, the number of adult males, and the population density of the animals, which the team considered more likely to be related to adaptive strategies.

“The contrast could not be more stark” between how the two hypotheses fared, says William McGrew, a primatologist at the University of Cambridge in the United Kingdom, who praises the study as a “monumental collaborative effort.” Joan Silk, an anthropologist at Arizona State University, Tempe, agrees. The study “weighs competing hypotheses systematically,” she says. “Advocates of the human impact hypothesis … must challenge [the study’s] empirical findings, or modify their position.”

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How Evolutionary Principles Could Help Save Our World

The age of the Anthropocene–the scientific name given to our current geologic age–is dominated by human impacts on our environment. A warming climate. Increased resistance of pathogens and pests. A swelling population. Coping with these modern global challenges requires application of what one might call a more-ancient principle: evolution. That’s the recommendation of a diverse group of researchers, in a paper published today in the online version of the journal Science. A majority of the nine authors on the paper have received funding from the National Science Foundation (NSF).

“Evolution isn’t just about the past anymore, it’s about the present and the future,” said Scott Carroll, an evolutionary ecologist at University of California-Davis and one of the paper’s authors. Addressing societal challenges–food security, emerging diseases, biodiversity loss–in a sustainable way is “going to require evolutionary thinking.” The paper reviews current uses of evolutionary biology and recommends specific ways the field can contribute to the international sustainable development goals (SDGs), now in development by the United Nations.

Their recommendations include gene therapies to treat disease, choosing drought-and-flood-resistant crop varieties and altering conservation strategies to protect land with high levels of genetic diversity. Evolutionary biologists don’t have all the answers, said Smith. And using applied evolution is not without risk. But we have reached a point “where we need to take risks in many cases,” he said. “We can’t just sit back and be overly conservative, or we’re going to lose the game.”

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Why Humans Don’t Suffer From Chimpanzee Malaria: DNA Region Controlling Red Blood Cell Invasion Holds Genetic Key to Infection

By comparing the genomes of malaria parasites that affect chimpanzees and those that affect humans, researchers discovered that it is the difference in the parasites’ surface proteins that determine which host it will infect.

Out of a genome of approximately 5,500 genes, researchers found that most genes have directly equivalent counterparts between the human and primate parasites. However, portions of the P. falciparum genome that differed most profoundly from the P. reichenowi parasite that infects chimpanzees were found to encode proteins that help the parasite to bind to and invade red blood cells, which is where the parasite grows and multiplies. “Discovering that the key differences lie in genes responsible for red blood cell invasion reassures us that we’ve been looking in the right place,” says Dr Thomas Otto, first author at the Wellcome Trust Sanger Institute. “Researchers have identified surface proteins as promising vaccine candidates already; and our finding adds more support, showing that it is the difference in the parasites’ surface proteins that determine which host it will infect.”

This is the first time that an essentially complete genome has been produced for a malaria parasite that infects such a close relative of humans. It provides the first systematic view of the differences between parasites that infect humans and those that infect our close relatives. Human malaria emerged from the Great Apes, so this comparison using chimpanzee malaria is the closest that scientists have come to a full catalogue of the changes associated with parasites switching from our primate relatives into humans.

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Once Living in the Shadows, UCLA Student Takes Pride in His Binational Status

Human Biology and Society student featured in a recent UCLA Newsroom article. 

Intervention in 6-month-olds with Autism Ameliorates Symptoms, Alleviates Developmental Delay

Treatment at the earliest age when symptoms of autism spectrum disorder (ASD) appear – sometimes in infants as young as 6 months old – significantly reduces symptoms so that, by age 3, most who received the therapy had neither ASD nor developmental delay, a UC Davis MIND Institute research study has found.

“Autism treatment in the first year of life: A pilot study of Infant Start, a parent-implemented intervention for symptomatic infants,” is co-authored by UC Davis professors of Psychiatry and Behavioral Sciences Sally J. Rogers and Sally Ozonoff. It is published online today in the Journal of Autism and Developmental Disorders.  “Most of the children in the study, six out of seven, caught up in all of their learning skills and their language by the time they were 2 to 3,” said Rogers, the study’s lead author and the developer of the Infant Start therapy. “Most children with ASD are barely even getting diagnosed by then.”

Given the preliminary nature of the findings, the study only suggests that treating these symptoms so early may lessen problems later. Larger, well controlled studies are needed to test the treatment for general use. However, the researchers said that this initial study is significant because of the very young ages of the infants, the number of symptoms and delays they exhibited early in life, the number of comparison groups involved, and because the intervention was low intensity and could be carried out by the parents in everyday routines.

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Nature or Nurture? It’s All About the Message

Were Albert Einstein and Leonardo da Vinci born brilliant or did they acquire their intelligence through effort?  No one knows for sure, but telling people the latter – that hard work trumps genes – causes instant changes in the brain and may make them more willing to strive for success, indicates a new study from Michigan State University.

“Giving people messages that encourage learning and motivation may promote more efficient performance,” said Schroder, a doctoral student in clinical psychology whose work is funded by the National Science Foundation. “In contrast, telling people that intelligence is genetically fixed may inadvertently hamper learning.”

The MSU study, which appears online in the journal Biological Psychology, offers what could be the first physiological evidence to support those findings, in the form of a positive brain response. “These subtle messages seem to have a big impact, and now we can see they have an immediate impact on how the brain handles information about performance,” Schroder said.

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Walking Fish Reveal How Our Ancestors Evolved Onto Land

Researchers at McGill University published in the journal Nature, turned to a living fish, called Polypterus, to help show what might have happened when fish first attempted to walk out of the water. Polypterus is an African fish that can breathe air, ‘walk’ on land, and looks much like those ancient fishes that evolved into tetrapods. The team of researchers raised juvenile Polypterus on land for nearly a year, with an aim to revealing how these ‘terrestrialized’ fish looked and moved differently. “Stressful environmental conditions can often reveal otherwise cryptic anatomical and behavioural variation, a form of developmental plasticity”, says Emily Standen, a former McGill post-doctoral student who led the project, now at the University of Ottawa. “We wanted to use this mechanism to see what new anatomies and behaviours we could trigger in these fish and see if they match what we know of the fossil record.”

The fish showed significant anatomical and behavioural changes. The terrestrialized fish walked more effectively by placing their fins closer to their bodies, lifted their heads higher, and kept their fins from slipping as much as fish that were raised in water. “Anatomically, their pectoral skeleton changed to become more elongate with stronger attachments across their chest, possibly to increase support during walking, and a reduced contact with the skull to potentially allow greater head/neck motion,” says Trina Du, a McGill Ph.D. student and study collaborator. “Because many of the anatomical changes mirror the fossil record, we can hypothesize that the behavioural changes we see also reflect what may have occurred when fossil fish first walked with their fins on land”, says Hans Larsson, Canada Research Chair in Macroevolution at McGill and an Associate Professor at the Redpath Museum.

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