Genome duplications in spiders and scorpions
(pug) In their attempts to understand the diversity of nature and its evolutionary mechanisms, evolutionary biologists rely on the comparative analysis of genomes. The term “genome” refers to the entirety of the genetic material that is encoded in each individual cell of an organism and contains information that dictates how species-specific morphological structures are formed. For instance, the genome of a fruit fly encodes the information for developing wings, whereas a spider’s genome contains the code for it to grow spinnerets and venom glands. Thus far, a duplication of the genome has only been determined for vertebrates. Now, for the first time, an international team of scientists collaborating with the University of Göttingen has found that the genomes of spiders and scorpions similarly underwent duplication. The results have been published in the scientific journal BMC Biology.
Indeed, humans have two copies of numerous genes, whilst fish often have as many as four copies. Evolutionary biologists assume that such genome duplications provide rich genetic material for new morphological innovations. They speak of a "playground for evolution” in this context. A team, headed by scientists from Oxford Brookes University, Baylor College of Medicine's Human Genome Sequencing Center and the University of Göttingen, sequenced the genomes of a spider and a scorpion and compared their gene content to that of other animals. "We have now finally identified an animal group in which genome duplications occurred independently from those observed in vertebrate animals,” says Prof. Alistair McGregor of the Oxford Brookes University. "For the first time, we can compare the impact of this fascinating biological phenomenon on the occurrence of innovations.”
Beetles smell with mouth and antennae
The red flour beetle Tribolium castaneum is an emerging insect model organism representing the largest insect order, Coleoptera, which encompasses several serious agricultural and forest pests. Despite the ecological and economic importance of beetles, most insect olfaction studies have so far focused on dipteran, lepidopteran, or hymenopteran systems.
We present in "BMC Biology" the first detailed morphological description of a coleopteran olfactory pathway in combination with genome-wide expression analysis of the relevant gene families involved in chemoreception.
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Disrupting housefly gene reverses sex
Science AAAS wrote in their newest issue: "Sex comes in many forms, even when considered at the molecular level. In different animals, the chromosomes and specific genes that function in sex determination vary widely. As a case in point, the familiar housefly displays a highly variable sex determination system. In this animal, the male determiner (M-factor) instructs male development when it is active, but female development results when it is inactive. Sharma et al. now identify the housefly M-factor, which arose via the co-option of existing genes, gene duplication, and neofunctionalization. The findings elucidate the remarkable diversity in sex-determining pathways and the forces that drive this diversity."
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Article in Science AAAS