Hot off the presses! May 01 Trends Genet

The May 01 issue of the Trends Genet is now up on Pubget (About Trends Genet): if you're at a subscribing institution, just click the link in the latest link at the home page. (Note you'll only be able to get all the PDFs in the issue if your institution subscribes to Pubget.)

Latest Articles Include:

• Editorial Board
  - Trends Genet 25(5):i (2009)
  
• Weak functional constraints on phosphoproteomes
  - Trends Genet 25(5):193-197 (2009)
  Owing to their crucial roles in regulating protein function, phosphorylation sites (phosphosites) are expected to be evolutionarily conserved. However, mixed results regarding this prediction have been reported. We resolve these contrasting conclusions to show that phosphosites are, on average, more conserved than non-phosphorylated equivalent residues when their enrichment in disordered regions of proteins is taken into account. Phosphosites of known function are dramatically more conserved than those with no characterized function, indicating that the apparent rapid evolution of phosphoproteomes results from a large fraction of phosphosites being non-functional. Our findings highlight the need to use evolutionary information to identify functional regulatory features such as post-translational modifications of eukaryotic proteomes.
• Potential of fish opsin gene duplications to evolve new adaptive functions
  - Trends Genet 25(5):198-202 (2009)
  The duplication of four cone-opsin gene families is heavily involved in visual adaptation in bony fish. We found that two gene families for the middle-wave range of the vision spectrum have, on average, older duplications followed by accelerated amino acid substitution, in comparison with the other two families that define the boundaries. This could be due to the difference in the potential to evolve new functions; middle-wave genes should have greater contribution to adaptive vision evolution through gene duplication.
• How to become a parasite – lessons from the genomes of nematodes
  - Trends Genet 25(5):203-209 (2009)
  The phylum Nematoda is biologically diverse; it includes parasites of plants and animals in addition to free-living taxa. To date, the genomes of six nematodes have been sequenced. Comparative analyses of these ecologically diverse nematodes are beginning to reveal the mechanisms by which parasites arise and how they evolve. Here, we discuss some emerging principles for the mechanisms and evolution of parasitism. First, horizontal gene transfer represents a common theme in nematode parasites. Second, the human parasite Brugia malayi lost otherwise essential genes most probably owing to the mutualistic relationship with a bacterial endosymbiont. Finally, some parasitic features evolved under free-living conditions. A recent study revealed a conserved endocrine mechanism controlling the formation of dauer and infective larvae in nematodes.
• How confident can we be that orthologs are similar, but paralogs differ?
  - Trends Genet 25(5):210-216 (2009)
  Homologous genes are classified into orthologs and paralogs, depending on whether they arose by speciation or duplication. It is widely assumed that orthologs share similar functions, whereas paralogs are expected to diverge more from each other. But does this assumption hold up on further examination? We present evidence that orthologs and paralogs are not so different in either their evolutionary rates or their mechanisms of divergence. We emphasize the importance of appropriately designed studies to test models of gene evolution between orthologs and between paralogs. Thus, functional change between orthologs might be as common as between paralogs, and future studies should be designed to test the impact of duplication against this alternative model.
• Complications of complexity: integrating environmental, genetic and hormonal control of insect diapause
  - Trends Genet 25(5):217-225 (2009)
  Understanding gene interaction and pleiotropy are long-standing goals of developmental and evolutionary biology. We examine the genetic control of diapause in insects and show how the failure to recognize the difference between modular and gene pleiotropy has confounded our understanding of the genetic basis of this important phenotype. This has led to complications in understanding the role of the circadian clock in the control of diapause in Drosophila and other insects. We emphasize three successive modules – each containing functionally related genes – that lead to diapause: photoperiodism, hormonal events and diapause itself. Understanding the genetic basis for environmental control of diapause has wider implications for evolutionary response to rapid climate change and for the opportunity to observe evolutionary change in contemporary time.
• The W, X, Y and Z of sex-chromosome dosage compensation
  - Trends Genet 25(5):226-233 (2009)
  In species with highly differentiated sex chromosomes, imbalances in gene dosage between the sexes can affect overall organismal fitness. Regulatory mechanisms were discovered in several unrelated animals, which counter gene-dose differences between females and males, and these early findings suggested that dosage-compensating mechanisms were required for sex-chromosome evolution. However, recent reports in birds and moths contradict this view because these animals locally compensate only a few genes on the sex chromosomes, leaving the majority with different expression levels in males and females. These findings warrant a re-examination of the evolutionary forces underlying dosage compensation.
• Thirty years of Mus spretus: a promising future
  - Trends Genet 25(5):234-241 (2009)
  Extensive genetic polymorphisms in Mus spretus have ensured its widespread use in many areas of genetics. With the recent increase in the number of single nucleotide polymorphisms available for laboratory mouse strains, M. spretus is becoming less appealing, in particular for genetic mapping. Although M. spretus mice are aggressive and poor breeders, they have a bright future because they provide phenotypes unobserved in laboratory strains, and tools are available for modifying their genome and dissecting the genetic architecture of complex traits. Furthermore, they provide information on fundamental genetic questions, such as the details of evolution of genomes and speciation. Here, we examine the use of M. spretus from these perspectives. The impending completion of the M. spretus genome sequence will synergize these advantages.