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Archive - Mar 12, 2017

A Closer Look at Brain Organoid Development

How close to reality are brain organoids, and which molecular mechanisms underlie the remarkable self-organizing capacities of tissues? Researchers already have succeeded in growing so-called "cerebral organoids" in a dish - clusters of cells that self-organize into small brain-like structures. Dr. Juergen Knoblich and colleagues have now further characterized these organoids and published their results online on March 10, 2017 in The EMBO Journal. The article is titled “Self‐Organized Developmental Patterning and Differentiation in Cerebral Organoids.” The scientists demonstrate that, as in the human brain, so-called forebrain organizing centers orchestrate developmental processes in the organoid, and that organoids recapitulate the timing of neuronal differentiation events found in human brains. The development of the human brain from just a few cells to a thinking organ is one of the great mysteries of biology. In the past decade, Dr. Knoblich and his team at the Institute of Molecular Biotechnology of the Austrian Academy of Sciences have pioneered brain organoid technology to investigate this intriguing process. Understanding normal organoid development is a prerequisite to using this powerful system to explore the possibility of modeling human developmental diseases.

RNA Interference Approach Could Save Millions of Tons of Crops Each Year from Contamination with Aflatoxin, a Major Threat to Health and Food Security, Especially in Developing Parts of the World

Researchers at the University of Arizona have found a promising way to prevent the loss of millions of tons of crops to a fungus each year, offering the potential to dramatically improve food security, especially in developing countries. The team's approach uses transgenic corn plants that produce small RNA molecules that prevent fungi from producing aflatoxin, highly toxic substances that can render an entire harvest unsafe for human consumption even in small amounts. Although extensive field testing will have to precede widespread application of the new technique in agricultural settings around the world, the results of the study, published online on March 10, 2017 in Science Advances, showed that transgenic corn plants infected with the fungus suppressed toxin levels below detectable limits. Crops all over the world are susceptive to infection by fungi of various Aspergillus species, a fungus that produces secondary metabolites known as aflatoxins. These compounds have been implicated in stunting children's growth, increasing the risk for liver cancer, and making people more susceptible to diseases such as HIV and malaria. The open-access Science Advances article is titled “Aflatoxin-free transgenic maize using host-induced gene silencing.” Unlike in the U.S., where crops intended for human consumption are tested for aflatoxin and incinerated once levels approach 20 parts per billion (equivalent to one drop of water in a 22,000-gallon pool), no testing is available in many developing parts of the world, especially in Africa, where millions of people depend on consuming what they harvest. There, toxin levels up to 100,000 parts per billion have been measured, says study leader Dr. Monica Schmidt, an Assistant Professor in the UA's School of Plant Sciences and a member of the UA's BIO5 Institute.

Repeated Convergent Evolotion: How Rove Beetles Keep Evoloving into Army Ant Parasites

Marauding across the tropical forest floor, aggressive army ant colonies harbor hidden enemies within their ranks. The impostors look and smell like army ants, march with the ants, and even groom the ants. But far from being altruistic nest-mates, these creatures are parasitic beetles, engaged in a game of deception. Through dramatic changes in body shape, behavior, and pheromone chemistry, the beetles gain their hostile hosts' acceptance, duping the ants so they can feast on the colony brood. This phenomenon did not evolve just once. Instead, these beetles arose at least a dozen separate times from non-ant-like ancestors. This discovery, published online on March 9, 2017 in Current Biology, provides evidence that evolution has the capacity to repeat itself in an astonishingly predictable way. The article is titled “"Deep-Time Convergence in Rove Beetle Symbionts of Army Ants.” "These beetles represent a new and really stunning system of convergent evolution," says study co-author and evolutionary biologist Joseph Parker, Ph.D., of Columbia University and the American Museum of Natural History. "It's an elaborate symbiosis, which has evolved in a stereotyped way, multiple times from free-living ancestors." The ant-mimicking beetles all belong to the Staphylinidae, or rove beetles, but don't mistake them for close relatives: the last common ancestor of the beetles in the study lived 105 million years ago, at about the time that humans split from mice. "What's exceptional is that this convergent system is evolutionarily ancient," says Dr. Parker. Although most other convergent systems, such as Darwin's finches, three-spined stickleback, and African lake cichlid fish, are a few million years old at most, this newly discovered example extends back into the Early Cretaceous.