In humans and most mammals, sex is governed by a chromosome determination system, specifically an XX/XY sex determination system whereby individuals with two X chromosomes are female and those with X and Y chromosomes are male. In honeybees (Apis mellifera), a single gene has been shown to be responsible for sex determination. The gene is known as csd (complementary sex determiner), and if an individual has two heterozygous copies it will be a female, whereas if it is homozygous or hemizygous (i........ Read more »
Martin Hasselmann, Tanja Gempe, Morten Schiøtt, Carlos Nunes-Silva, Marianne Otte, & Martin Beye. (2008) Evidence for the evolutionary nascence of a novel sex determination pathway in honeybees. Nature, 454(7203), 519-522. DOI: 10.1038/nature07052
A short while ago, a draft sequence of the Platypus genome was announced in Nature. In this week's issue of Nature, another consortium of researchers reports the draft sequence of the Amphioxus (also known as lancelets) genome. Amphioxus is a group of worm-like organisms that live in the sea floor. Like us, they are chordates, which means that they possess a notochord - a rod of tissue in the dorsal part of the organism - amongst other common features. Chordates are comprised of three linea........ Read more »
Nicholas Putnam, Thomas Butts, David E Ferrier, Rebecca F Furlong, Uffe Hellsten, Takeshi Kawashima, Marc Robinson-Rechavi, Eiichi Shoguchi, Astrid Terry, Jr-Kai Yu.... (2008) The amphioxus genome and the evolution of the chordate karyotype. Nature, 453(7198), 1064-1071. DOI: 10.1038/nature06967
Protein-coding DNA makes up only a small part of our genome. The rest of it is either not transcribed, or codes for RNA that does not become translated into proteins. Some of these non-coding RNAs include transfer RNA and ribosomal RNA, both key components of the translation machinery. Recently, scientists have discovered that many of the other non-coding RNAs are small RNAs, some of which may regulate gene expression and some which may turn out to be functionless i.e. transcriptional noise.In 2........ Read more »
A Beniaminov, E Westhof, & A Krol. (2008) Distinctive structures between chimpanzee and human in a brain noncoding RNA. RNA. DOI: 10.1261/rna.1054608
Last week I wrote about orchid species which attract wasps by mimicking the scent given off when caterpillars feed on leaves. It is one of the many fascinating ways in which orchids use mimicry in order to attract pollinators. In last Tuesday's Proceedings of the National Academy of Sciences, there was a paper on a different kind of mimicry. Some orchids use sexual mimicry to attract insects by tricking them into thinking that the flowers are their female counterparts. This is partly based ........ Read more »
Different orchid species have evolved intriguing ways of attracting pollinators. The most common method is one where the flower has morphological structures that mimic those of other species that provide food for the pollinators. In a recent paper in Current Biology, Brodmann et al. report the use of chemical mimicry in Epipactis helleborine. The E. helleborine orchid is a wasp-flower that inhabits dark forest understories where pollinators like honey bees and butterflies are rare. Instead, wasp........ Read more »
J BRODMANN, R TWELE, W FRANCKE, G HOLZLER, Q ZHANG, & M AYASSE. (2008) Orchids Mimic Green-Leaf Volatiles to Attract Prey-Hunting Wasps for Pollination. Current Biology, 18(10), 740-744. DOI: 10.1016/j.cub.2008.04.040
Nature has just announced that a draft sequence of the platypus (Ornithorhynchus anatinus) genome is now complete. The platypus is an interesting creature, because it has both mammalian and reptilian features. The platypus is thought to have split from the mammalian lineage along with the other monotremes quite early in evolutionary history. Around 166 million years ago, the monotremes are thought to have split from the lineage which later gave rise to marsupials and e... Read more »
Wesley Warren, LaDeana W Hillier, Jennifer A Marshall Graves, Ewan Birney, Chris P Ponting, Frank Grützner, Katherine Belov, Webb Miller, Laura Clarke, Asif T Chinwalla.... (2008) Genome analysis of the platypus reveals unique signatures of evolution. Nature, 453(7192), 175-183. DOI: 10.1038/nature06936
A fascinating paper which came out earlier this year provides both molecular and morphological evidence for the evolution of mysticetes, which are better known as baleen whales. The paper by Deméré et al. is titled "Morphological and Molecular Evidence for a Stepwise Evolutionary Transition from Teeth to Baleen in Mysticete Whales" and was published in the February 2008 issue of Systematic Biology.Extant whales can be divided into two groups: toothed whales (odontocetes) ........ Read more »
Thomas Deméré, Michael McGowen, Annalisa Berta, & John Gatesy. (2008) Morphological and Molecular Evidence for a Stepwise Evolutionary Transition from Teeth to Baleen in Mysticete Whales. Systematic Biology, 57(1), 15-37. DOI: 10.1080/10635150701884632
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