Changes in the Expression Patterns of the Genes Involved in the Segregation and Function of Inner Cell Mass and Trophectoderm Lineages During Porcine Preimplantation Development

In mouse embryos, segregation of the inner cell mass (ICM) and trophectoderm (TE) lineages is regulated by genes, such as OCT-4, CDX2 and TEAD4. However, the molecular mechanisms that regulate the segregation of the ICM and TE lineages in porcine embryos remain unknown. To obtain insights regarding the segregation of the ICM and TE lineages in porcine embryos, we examined the mRNA expression patterns of candidate genes, OCT-4, CDX2, TEAD4, GATA3, NANOG, FGF4, FGFR1-IIIc and FGFR2-IIIc, in blastocyst and elongated stage embryos. In blastocyst embryos, the expression levels of OCT-4, FGF4 and FGFR1-IIIc were significantly higher in the ICM than in the TE, while the CDX2, TEAD4 and GATA3 levels did not differ between the ICM and TE. The expression ratio of CDX2 to OCT-4 (CDX2/OCT-4) also did not differ between the ICM and TE at the blastocyst stage. In elongated embryos, OCT-4, NANOG, FGF4 and FGFR1-IIIc were abundantly expressed in the embryo disc (ED; ICM lineage), but their expression levels were very low in the TE. In contrast, the CDX2, TEAD4 and GATA3 levels were significantly higher in the TE than in the ED. In addition, the CDX2/OCT-4 ratio was markedly higher in the TE than in the ED. We demonstrated that differences in the expression levels of OCT-4, CDX2, TEAD4, GATA3, NANOG, FGF4, FGFR1-IIIc and FGFR2-IIIc genes between ICM and TE lineages cells become more clear during development from porcine blastocyst to elongated embryos, which indicates the possibility that in porcine embryos, functions of ICM and TE lineage cells depend on these gene expressions proceed as transition from blastocyst to elongated stage.     

Effect of an Introduced Phytoene Synthase Gene Expression on Carotenoid Biosynthesis in the Marine Diatom Phaeodactylum tricornutum

Carotenoids exert beneficial effects on human health through their excellent antioxidant activity. To increase carotenoid productivity in the marine Pennales Phaeodactylum tricornutum, we genetically engineered the phytoene synthase gene (psy) to improve expression because RNA-sequencing analysis has suggested that the expression level of psy is lower than other enzyme-encoding genes that are involved in the carotenoid biosynthetic pathway. We isolated psy from P. tricornutum, and this gene was fused with the enhanced green fluorescent protein gene to detect psy expression. After transformation using the microparticle bombardment technique, we obtained several P. tricornutum transformants and confirmed psy expression in their plastids. We investigated the amounts of PSY mRNA and carotenoids, such as fucoxanthin and β-carotene, at different growth phases. The introduction of psy increased the fucoxanthin content of a transformants by approximately 1.45-fold relative to the levels in the wild-type diatom. However, some transformants failed to show a significant increase in the carotenoid content relative to that of the wild-type diatom. We also found that the amount of PSY mRNA at log phase might contribute to the increase in carotenoids in the transformants at stationary phase.     

Geographical variations in infection by larval Anisakis simplex and Contracaecum osculatum (Nematoda, Anisakidae) in walleye pollock Theragra chalcogramma stocks off Hokkaido, Japan

ABSTRACT: Stocks of walleye pollock Theragra chalcogramma collected from: (i) the Sea of Japan (off Rebun Island and Kumaishi); (ii) the Pacific coast (off Shikabe and eastern Hokkaido); and (iii) Nemuro Strait off Hokkaido, northern Japan, were examined for anisakid nematodes during December 1999 to February 2000, and the prevalence and abundance of Anisakis simplex and Contracaecum osculatum larvae were compared among the various sampling sites for fish of the same size and age. Anisakis simplex was generally more abundant than C. osculatum . Infection by A. simplex varied between the aforementioned stocks of walleye pollock as well as within stocks, whereby fish from off Rebun Island and Nemuro Strait were infected the most, followed by those from off the Pacific coast and Kumaishi. Infection by C. osculatum differed between the host stocks, and C. osculatum was the most abundant among the fish from Nemuro Strait. The infection variations seemed to be due to differences in host growth rate, host feeding habit, and the distribution of marine mammal final hosts. The results indicate that these two larval nematodes are useful biological indicators for the population study of walleye pollock in Japanese waters.     

Glycosphingolipid receptors for pathogenic vibrios in intestines of mariculture fish

Vibrios are highly motile, facultatively anaerobic bacteria that are ubiquitous in aquatic environments and part of the normal intestinal microflora of healthy fish, but some species can cause vibriosis. The adherence of vibrios to host fish intestines is a significant event not only for their survival and growth, but also in terms of pathogenicity. However, the molecular mechanism underlying the adhesion of vibrios to the intestinal tract of fish is not fully understood. We report here the identification of intestinal glycosphingolipid (GSL) receptors to which pathogenic vibrios attach in typical mariculture fish. Thin-layer chromatography overlay assays using five species of ³⁵S-labeled vibrios and intestinal glycosphingolipids of seven species of mariculture fish revealed that all of the fish tested possessed GM3 (NeuAcα2-3Galβ1-4Glcβ1-1′Cer) and/or GM4 (NeuAcα2-3Galβ1-1′Cer) as major acidic intestinal GSLs and that all of the vibrios tested specifically adhered to GM3 and/or GM4. Our results demonstrate that these GSLs were able to function as a receptor for the various vibrios tested. Analysis of the relationship between sugar structure and receptor activity for vibrios revealed that ‘NeuAcα2-3Galβ1-’ is required at the non-reducing end of glycosphingolipids for the bacteria to attach.     

An observation of PKJKP: inferences on inner core shear properties

The seismic phase PKJKP, which traverses the inner core as a shear wave and would provide direct evidence for its solidity, has been difficult to detect. Using stacked broadband records from the Grafenberg array in Germany, we documented a high signal-to-noise phase, the arrival time and slowness of which agree with theoretical predictions for PKJKP. The back azimuth of this arrival is also consistent with predictions for PKJKP, as is the comparison with a pseudoliquid inner core model. Envelope modeling of the PKJKP waveform implies a shear velocity gradient with depth in the inner core that is slightly larger than that in the preliminary reference Earth model.