The sea urchin major yolk protein is synthesized mainly in the gut inner epithelium and the gonadal nutritive phagocytes before and during gametogenesis

Major yolk protein (MYP), the predominant component of yolk granules in sea urchin eggs, is also contained in the coelomic fluid and nutritive phagocytes of the gonad in both sexes. MYP is stored in ovarian and testicular nutritive phagocytes prior to gametogenesis and is used during gametogenesis as material for synthesizing proteins and other components necessary for eggs and sperm. To reveal the expression profile and the main production site of MYP, we analyzed MYP mRNA expression in immature and maturing Pseudocentrotus depressus. Real‐time reverse‐transcribed polymerase chain reaction analysis showed that MYP mRNA was expressed predominantly in the digestive tract (stomach, intestine and rectum) and the gonad of both sexes. The total amounts of MYP mRNA in the whole digestive tract and in the whole gonad were at similar levels in both immature and maturing sea urchins. MYP mRNA was also detected in white morula cells and vibratile cells separated from the coelomic fluid by density gradient centrifugation, but the expression levels in these cells were very low compared with those in the digestive tract and the gonad. Using in situ hybridization analysis, MYP mRNA was detected in the inner epithelium of the digestive tract and in nutritive phagocytes of the ovary and testis, but was not detected in the germ cells. We conclude that the adult sea urchin has two predominant production sites for MYP regardless of sex and reproductive stage: the inner epithelium of the digestive tract and the nutritive phagocytes of the gonad. Mol. Reprod. Dev. 77: 59–68, 2010. © 2009 Wiley‐Liss, Inc.     

Genomewide high-density SNP linkage analysis of 236 Japanese families supports the existence of schizophrenia susceptibility loci on chromosomes 1p, 14q, and 20p

The Japanese Schizophrenia Sib-Pair Linkage Group (JSSLG) is a multisite collaborative study group that was organized to create a national resource for affected sib pair (ASP) studies of schizophrenia in Japan. We used a high-density single-nucleotide–polymorphism (SNP) genotyping assay, the Illumina BeadArray linkage mapping panel (version 4) comprising 5,861 SNPs, to perform a genomewide linkage analysis of JSSLG samples comprising 236 Japanese families with 268 nonindependent ASPs with schizophrenia. All subjects were Japanese. Among these families, 122 families comprised the same subjects analyzed with short tandem repeat markers. All the probands and their siblings, with the exception of seven siblings with schizoaffective disorder, had schizophrenia. After excluding SNPs with high linkage disequilibrium, we found significant evidence of linkage of schizophrenia to chromosome 1p21.2-1p13.2 (LOD=3.39) and suggestive evidence of linkage to 14q11.2 (LOD=2.87), 14q11.2-q13.2 (LOD=2.33), and 20p12.1-p11.2 (LOD=2.33). Although linkage to these regions has received little attention, these regions are included in or partially overlap the 10 regions reported by Lewis et al. that passed the two aggregate criteria of a meta-analysis. Results of the present study—which, to our knowledge, is the first genomewide analysis of schizophrenia in ASPs of a single Asian ethnicity that is comparable to the analyses done of ASPs of European descent—indicate the existence of schizophrenia susceptibility loci that are common to different ethnic groups but that likely have different ethnicity-specific effects.     

Regulation of isthmic Fgf8 signal by sprouty2

Fgf8 functions as an organizer at the mes/metencephalic boundary (isthmus). We showed that a strong Fgf8 signal activates the Ras-ERK signaling pathway to organize cerebellar differentiation. Sprouty2 is expressed in an overlapping manner to Fgf8, and is induced by Fgf8. Its function, however, is indicated to antagonize Ras-ERK signaling. Here, we show the regulation of Fgf8 signaling in relation to Sprouty2. sprouty2 expression was induced very rapidly by Fgf8b, but interfered with ERK activation. sprouty2 misexpression resulted in a fate change of the presumptive metencephalon to the mesencephalon. Misexpression of a dominant negative form of Sprouty2 augmented ERK activation, and resulted in anterior shift of the posterior border of the tectum. The results indicate that Fgf8 activates the Ras-ERK signaling pathway to differentiate the cerebellum, and that the hyper- or hypo-signaling of this pathway affects the fate of the brain vesicles. Sprouty2 may regulate the Fgf8-Ras-ERK signaling pathway for the proper regionalization of the metencephalon and mesencephalon.     

Hormonal regulation of serine dehydratase activity in primary cultures of adult rat hepatocytes

The capacity of the following peptides to stimulate steroidogenesis in suspensions of capsule (largely glomerulosa) and fasciculata/reticularis cells from rat adrenals was studied: ACTH_1–24, ACTH_1–13-amide, α-MSH, γ₁-MSH, γ-MSH precursor, ACTH_4–10, CLIP, and ovine and human β-lipotropin. Only α-MSH and ACTH_1–13-amide stimulated glomerulosa cells alone, without effect on fasciculata/reticularis cells. Like ACTH_1–24 the two samples of β-lipotropin stimulated both capsule and inner zone cell types in a similar manner. Their activity is attributable to slight ACTH_1–39 contamination, as shown by HPLC fractionation. The other peptides lacked any activity. It is likely that the predicted specific glomerulosa stimulant from the pituitary closely resembles α-MSH.     

Diversity of laccase among Cryptococcus neoformans serotypes

The pathogenic yeast C. neoformans is classified into three varieties with five serotypes; var. grubii (serotype A), var. neoformans (serotype D), var. gattii (serotypes B and C), and serotype AD. Melanin is a virulence factor in the species, and its biosynthesis is catalyzed by laccase, encoded by the LAC1 gene. In order to estimate the natural variability of the LAC1 gene among Cryptococcus serotypes, the laccase protein sequence from 55 strains was determined and the phylogenetic relationships between cryptococcal and related fungal laccases revealed. The deduced laccase proteins consisted of 624 amino acid residues in serotypes A, D and AD, and 613 to 615 residues in serotypes B and C. Intra-serotype amino acid variation was marginal within serotypes A and D, and none was found within serotypes AD and C. Maximum amino acid replacement occurred in two serotype B strains. The similarity in the deduced sequence ranged from 80 to 96% between serotypes. The sequence in the copper-binding regions was strongly conserved in the five serotypes. The laccases of the five serotypes were grouped together in the same clade of the phylogenetic tree reconstructed from different fungal laccases, suggesting a monophyletic clade.     

Non-requirement of calcium on protamine phosphorylation by calcium-activated, phospholipid-dependent protein kinase

Phosphorylation of clupeine sulfate by purified rat brain calcium-activated, phospholipid-dependent protein kinase (protein kinase C) was studied. In the absence of Ca2+, phosphatidylserine and diolein markedly stimulated its phosphorylation. However Ca2+ did not stimulate but inhibit this phosphorylation about 30% in the presence of phospholipids. Random polymer (Arg, Ser) 3:1 and (Lys, Ser) 3:1 could be phosphorylated by protein kinase C. In the presence of phospholipids Ca2+ is not needed for the phosphorylation of polymer (Arg, Ser) 3:1, while Ca2+ is necessary for polymer (Lys, Ser) 3:1. Non-requirement of Ca2+ on clupeine phosphorylation by protein kinase C is briefly discussed.     

Characterization of a human ''midisatellite'' sequence.

We have examined the structure and DNA sequence of a human genomic locus that consists of a large hypervariable region made up of repeats of a simple sequence. With several restriction enzymes, the locus shows many restriction fragments that vary quantitatively as well as qualitatively. Other restriction enzymes produce only a single, high-molecular-weight fragment at this locus. Almost all of the fragments are revealed with a simple sequence probe. Southern transfers of the high-molecular-weight restriction fragments produced by the restriction enzymes NotI and SfiI, resolved by pulsed-field gel electrophoresis, gave at most two fragments, demonstrated to be allelic, showing that the majority of the restriction fragments seen in the complex patterns are at a single locus. The estimated size of the region homologous to the probe varied from 250 to 500 kilobases. DNA sequencing indicated that the region consists of tandem repeats of a 40-base-pair sequence. Some homology was detected to the tandem repeating units of the insulin gene and the zetaglobin pseudogene hypervariable regions, and to the "minisatellite" DNA at the myoglobin locus.     

Mapping Approaches to Gene Identification in Humans

Although a number of human genes that cause disease have been traced through the defective product, most genetic defects are recognized only by phenotype. When the biochemical defect is unknown, a gene can be located only through molecular approaches based on coinheritance (genetic linkage) of the disease phenotype with a particular allele of a polymorphic DNA marker that has already been mapped to a specific chromosomal region. Linkage studies in affected families have already localized genes for several important diseases, including cystic fibrosis. Finding a genetic linkage in families in which a disease segregates requires that the human genetic map have a large number of polymorphic markers; when the map is dense enough, any disease gene can be located by linkage to a known marker. Many DNA segments with a high degree of polymorphism are being found and mapped as markers in normal reference pedigrees. Genetic linkage mapping has implications even broader than its application to prenatal diagnosis or therapeutic strategy; analyzing mutations in important genes will illuminate basic mechanisms in molecular biology and the early events that lead to cancer and other disorders.