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Science,
2001]
RNA molecules are a constant source of joy to molecular biologists: They come in all shapes and sizes, and perform diverse informational, structural, and catalytic tricks in living cells. Perhaps less appreciated is their facility for regulating gene expression. Small regulatory RNAs figure prominently in two fascinating phenomena: gene inactivation by RNA interference (RNAi), and the control of gene expression during development.
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Dev Cell,
2003]
Polycomb and Trithorax group proteins have been shown to regulate Hox gene expression in files and mammals, but not in worms. Two reports in this issue of Developmental Cell establish a first link between Polycomb-like genes and Hox gene regulation in C. elegans. However, sequence comparison indicates that these genes may not be homologous to the fly Polycomb genes, suggesting that independent gene recruitment occurred during nematode evolution.
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Proc Natl Acad Sci U S A,
2003]
The discovery of transgene silencing in plants and double-stranded RNA (dsRNA) interference in the worm Caenorhabditis elegans has led to the latest revolution in molecular biology, RNA interference (RNAi). Over 10 years ago it was noted that several transgenic plant lines each containing the same ectopic transgene not only failed to be expressed but also inhibited the expression of the endogenous gene. Similarly, a determined Craig Mello and Andy Fire, attempting to reduce gene function using using antisense RNA in the worm, discovered a minor contaminant in their antisense RNA preparation effectively and repeatedly reduced expression of the endogenous gene. In both cases, dsRNA homologous to the gene of interest was responsible for these observations. In the last 4 years, these discoveries have been extended to include protozoa,
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[
Science,
1998]
The near completion of the sequence of the C. elegans genome should provide researchers with a gold mine of information on topics ranging from evolution to gene
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Mol Cell,
2014]
In this issue of Molecular Cell, Hendriks et al. (2014) uncover extensive oscillations in global gene expression during C. elegans development, in synchrony with the molting cycle.
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[
Science,
2000]
Gene duplication has generally been viewed as a necessary source of material for the origin of evolutionary novelties, but it is unclear how often gene duplicates arise and how frequently they evolve new functions. Observations from the genomic databases for several eukaryotic species suggest that duplicate genes arise at a very high rate, on average 0.01 per gene per million years. Most duplicated genes experience a brief period of relaxed selection early in their history, with a moderate fraction of them evolving in an effectively neutral manner during this period. However, the vast majority of gene duplicates are silenced within a few million years, with the few survivors subsequently experiencing strong purifying selection. Although duplicate genes may only rarely evolve new functions, the stochastic silencing of such genes may play a significant role in the passive origin of new species.
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Curr Biol,
2011]
What mechanisms coordinate the sequential pattern of gene expression during development of specialized cells? A small RNA-based mechanism is proposed to repress expression of genes during oogenesis.
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[
Nature,
2003]
Understanding how we grow old is a long-sought goal. A new large-scale study of gene expression in worms allows us to glimpse the complex biochemistry of lifespan.
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[
Nat Neurosci,
2001]
A characterization of C. elegans lacking the gene for Rim suggests that this protein may be involved in pruning synaptic vesicles for fusion, not in docking or organizing active zones.
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[
Nat Methods,
2011]
Engineering precise genetic changes in a genome is powerful way to study gene function, and several recent papers describe new applications of gene-editing tools. Working with researchers at Sangamo BioSciences, Howard Hughes Medical Institute investigator Barbara Meyer and her colleagues at the University of California, Berkeley, described the first systems for making targeted genomic modifications in the roundworm Caenorhabditis elegans, a valuable model organism (Wood et al., 2011).