Genome 10K: A Proposal to Obtain Whole-Genome Sequence for 10 000 Vertebrate Species

The human genome project has been recently complemented by whole-genome assessment sequence of 32 mammals and 24 nonmammalian vertebrate species suitable for comparative genomic analyses. Here we anticipate a precipitous drop in costs and increase in sequ

Complex organization of the Streptomyces avermitilis genes encoding the avermectin polyketide synthase

The avermectin (Av) polyketide synthase (PKS) and erythromycin (Er) PKS are encoded by modular repeats of DNA, but the genetic organization of the modules encoding Av PKS is more complex than Er PKS. Sequencing of several related DNA fragments from Streptomyces avermitilis that are part of the Av biosynthetic gene cluster, revealed that they encode parts of large multifunctional PKS proteins. The Av PKS proteins show strong similarity to each other, as well as similarity to Er PKS proteins [Donadio et al., Science 252 (1991) 675–679] and fatty acid synthases. Partial DNA sequencing of the 65-kb region containing all the related sequence elements in the avr genes provides evidence for twelve modular repeats encoding FAS-like domains. The genes encoding the Av PKS are organized as two sets of six modular repeats which are convergently transcribed.

timng of the last glacial maximum from observed sea level minima

During the Last Glacial Maximum, ice sheets covered large areas in northern latitudes, and global temperatures were significantly lower than today. But few direct estimates exist of the volume of the ice sheets, or the timing and rates of change during their advance and retreat. Here we analyze four distinct sediment facies in the shallow, tectonically stable Bonaparte Gulf, Australia - each of which is characteristic of a distinct range in sea level - to estimate the maximum volume of land-based ice during the last glaciation and the timing of the initial melting phase. We use faunal assemblages and preservation status of the sediments to distinguish open marine, shallow marine, marginal marine and brackish conditions, and estimate the timing and the mass of the ice sheets using radiocarbon dating and glacio-hydroisostatic modelling. Our results indicate that from at least 22,000 to 19,000 (calendar) years before present, land-based ice volume was at its maximum, exceeding today's grounded ice sheets by 52.5 x 10 exp 6 cu km. A rapid decrease in ice volume by about 10 percent within a few hundred years terminated the Last Glacial Maximum at 19,000 +/- 250 years.