Inferences of evolutionary history of a widely distributed mangrove species,Bruguiera gymnorrhiza,in the Indo‐West Pacific region

Inference of genetic structure and demographic history is fundamental issue in evolutionary biology. We examined the levels and patterns of genetic variation of a widespread mangrove species in the Indo‐West Pacific region, Bruguiera gymnorrhiza, using ten nuclear gene regions. Genetic variation of individual populations covering its distribution range was low, but as the entire species it was comparable to other plant species. Genetic differentiation among the investigated populations was high. They could be divided into two genetic clusters: the West and East clusters of the Malay Peninsula. Our results indicated that these two genetic clusters derived from their ancestral population whose effective size of which was much larger compared to the two extant clusters. The point estimate of speciation time between B. gymnorrhiza and Bruguiera sexangula was two times older than that of divergence time between the two clusters. Migration from the West cluster to the East cluster was much higher than the opposite direction but both estimated migration rates were low. The past Sundaland and/or the present Malay Peninsula are likely to prevent gene flow between the West and East clusters and function as a geographical or land barrier.     

Taxonomic review of the Sebastes vulpes complex (Scorpaenoidei: Sebastidae)

Ichthyological Research - A taxonomic review of the Sebastes vulpes complex (S. vulpes, S. zonatus and S. ijimae) established the existence of two valid species, Sebastes vulpes Döderlein in...     

TGF-beta isoform signaling regulates secondary transition and mesenchymal-induced endocrine development in the embryonic mouse pancreas

Transforming growth factor-beta (TGF-beta) superfamily signaling has been implicated in many developmental processes, including pancreatic development. Previous studies are conflicting with regard to an exact role for TGF-beta signaling in various aspects of pancreatic organogenesis. Here we have investigated the role of TGF-beta isoform signaling in embryonic pancreas differentiation and lineage selection. The TGF-beta isoform receptors (RI, RII and ALK1) were localized mainly to both the pancreatic epithelium and mesenchyme at early stages of development, but then with increasing age localized to the pancreatic islets and ducts. To determine the specific role of TGF-beta isoforms, we functionally inactivated TGF-beta signaling at different points in the signaling cascade. Disruption of TGF-beta signaling at the receptor level using mice overexpressing the dominant-negative TGF-beta type II receptor showed an increase in endocrine precursors and proliferating endocrine cells, with an abnormal accumulation of endocrine cells around the developing ducts of mid-late stage embryonic pancreas. This pattern suggested that TGF-beta isoform signaling may suppress the origination of secondary transition endocrine cells from the ducts. Secondly, TGF-beta isoform ligand inhibition with neutralizing antibody in pancreatic organ culture also led to an increase in the number of endocrine-positive cells. Thirdly, hybrid mix-and-match in vitro recombinations of transgenic pancreatic mesenchyme and wild-type epithelium also led to increased endocrine cell differentiation, but with different patterns depending on the directionality of the epithelial-mesenchymal signaling. Together these results suggest that TGF-beta signaling is important for restraining the growth and differentiation of pancreatic epithelial cells, particularly away from the endocrine lineage. Inhibition of TGF-beta signaling in the embryonic period may thus allow pancreatic epithelial cells to progress towards the endocrine lineage unchecked, particularly as part of the secondary transition of pancreatic endocrine cell development. TGF-beta RII in the ducts and islets may normally serve to downregulate the production of beta cells from embryonic ducts.     

Fucosyl-GM1a, an endoglycoceramidase-resistant ganglioside of porcine brain

The use of bovine brain has been prohibited in many countries because of the world-wide prevalence of mad cow disease, and thus porcine brain is expected to be a new source for the preparation of gangliosides. Here, we report the presence of a ganglioside in porcine brain which is strongly resistant to hydrolysis by endoglycoceramidase, an enzyme capable of cleaving the glycosidic linkage between oligosaccharides and ceramides of various glycosphingolipids. Five major gangliosides (designated PBG-1, 2, 3, 4, 5) were extracted from porcine brain by Folch's partition, followed by mild alkaline hydrolysis and PBA column chromatography. We found that PBG-2, but not the others, was strongly resistant to hydrolysis by the enzyme. After the purification of PBG-2 with Q-Sepharose, Silica gel 60 and Prosep-PB chromatographies, the structure of PBG-2 was determined by GC, GC-MS, FAB-MS and NMR spectroscopy as Fucalpha1-2Galbeta1-3GalNAcbeta1-4(NeuAcalpha2-3)Galbeta1-4Glcbeta1-1'Cer (fucosyl-GM1a). The ceramide was mainly composed of C18:0 and C20:0 fatty acids and d18:1 and d20:1 sphingoid bases. The apparent kcat/Km for fucosyl-GM1a was found to be 30 times lower than that for GM1a, indicating that terminal fucosylation makes GM1a resistant to hydrolysis by the enzyme. This report indicates the usefulness of endoglycoceramidase to prepare fucosyl-GM1a from porcine brain.     

Organotypic culture of adult rabbit retina

Organotypic culture systems of functional neural tissues are important tools in neurobiological research. Ideally, such a system should be compatible with imaging techniques, genetic manipulation, and electrophysiological recording. Here we present a simple interphase tissue culture system for adult rabbit retina that requires no specialized equipment and very little maintenance. We demonstrate the dissection and incubation of rabbit retina and particle-mediated gene transfer of plasmids encoding GFP or a variety of subcellular markers into retinal ganglion cells. Rabbit retinas cultured this way can be kept alive for up to 6 days with very little changes of the overall anatomical structure or the morphology of individual ganglion- and amacrine cells.     

Genome-wide association study of idiopathic hypersomnia in a Japanese population

Sleep and Biological Rhythms - Idiopathic hypersomnia (IH) is a rare sleep disorder characterized by excessive daytime sleepiness, great difficulty upon awakening, and prolonged sleep time. In...     

No apparent effects of the buccal cavity attaching parasite,Salmincola sp. (Copepoda: Lernaeopodidae), on a stream salmonid: a mark-recapture study

Ichthyological Research - We evaluated the effects of a buccal cavity attaching Salmincola sp. on white-spotted charr Salvelinus leucomaenis by mark-recapture method to compare body condition,...