We assessed the degree of population subdivision among global populations of green sea turtles, Chelonia mydas, using four microsatellite loci. Previously, a single-copy nuclear DNA study indicated significant malemediated gene flow among populations alternately fixed for different mitochondrial DNA haplotypes and that genetic divergence between populations in the Atlantic and Pacific Oceans was more common than subdivisions among populations within ocean basins. Even so, overall levels of variation at single-copy loci were low and inferences were limited. Here, the markedly more variable microsatellite loci confirm the presence of male-mediated gene flow among populations within ocean basins. This analysis generally confirms the genetic divergence between the Atlantic and Pacific. As with the previous study, phylogenetic analyses of genetic distances based on the microsatellite loci indicate a close genetic relationship among eastern Atlantic and Indian Ocean populations. Unlike the single-copy study, however, the results here cannot be attributed to an artifact of general low variability and likely represent recent or ongoing migration between ocean basins. Sequence analyses of regions flanking the microsatellite repeat reveal considerable amounts of cryptic variation and homoplasy and significantly aid in our understanding of population connectivity. Assessment of the allele frequency distributions indicates that at least some of the loci may not be evolving by the stepwise mutation model.

We have developed a small-scale method for isolating high-quality chromosomal DNA from Streptomyces species. The entire procedure may be carried out in 2-mL microcentrifuge tubes in one day. It has been tested both quantitatively and qualitatively to ensure reliability and reproducibility. DNA yields from a variety of Streptomyces species ranged from 30 micrograms DNA/50 mg cells to over 225 micrograms DNA/50 mg cells. We used the method to isolate DNA from cells grown in liquid culture, on solid media and from spore suspensions. DNA yields and quality were assessed by spectrophotometry, restriction endonuclease digestion and random-amplified polymorphic DNA-PCR (RAPD-PCR) analysis. These confirmed that this procedure is an efficient method for isolating large amounts of high-quality DNA from a wide range of Streptomyces species.

Sphyrna gilberti sp. nov. is described based on 54 specimens collected in the coastal waters of South Carolina, U.S.A. Morphologically, S. gilberti sp. nov. is separable from S. lewini (Griffith & Smith 1834) only in the number of precaudal vertebrae. Due to rarity of specimens and the highly migratory behavior of most sphyrnids, the range of S. gilberti sp. nov. is unknown.

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Atlantic bluefin tuna, Thunnus thynnus (Linnaeus, 1758), are highly migratory and capable of traversing large distances throughout the North Atlantic Ocean. However, the majority of spawning activity has only been reported from the Mediterranean Sea and Gulf of Mexico. In early April 2009, low numbers of very small larval bluefin tuna were collected within and south of the Yucatán Channel, and along the western boundary of the Loop Current, northeast of Campeche Bank. In situ current velocity measurements showed that these larvae were collected in moderate to strong northward flow regimes, suggesting that they were spawned outside of the Gulf of Mexico. Here we describe the location and oceanographic environment of these larval bluefin tuna collections, and compare the 2009 data with some historical collections in the area.