Association between antibody response against cytomegalovirus strain-specific glycoprotein H epitopes and HLA-DR

The gH of CMV is a major target for strain-specific neutralizing antibodies. To verify whether there is a correlation between HLA-DR type and strain-specific antibodies, antibodies against CMV gH in potential donors and recipients for renal transplantation were investigated. Among 471 subjects, 404 (86%) showed reactivity to CMV gH, but no antibodies against gH were detected in 67 (14%) subjects. The positive rates were over 80% in most HLA subpopulations. Fewer subjects with HLA-DR10 and DR11 had antibodies to CMV gH than did those without HLA-DR10 and DR11. HLA-DR10 and DR11 may be associated with fewer/non-responders for strain-specific neutralizing antibodies.     

Effect of founding events on coat colour polymorphism of Apodemus speciosus (Rodentia: Muridae) on the Izu Islands

To infer the evolutionary mechanism of phenotypic variation among isolated island populations, we investigated coat colour and genetic variation in the large Japanese field mouse (Apodemus speciosus) on the Izu Islands (Ohshima, Niijima, Kouzushima, and Miyakejima). Coat colour in the most remote population (Miyakejima) was unique and significantly darker than that in the other populations. Ohshima that is closest to the source population showed variation in coat colour within its population. Phylogeographical analyses using mitochondrial and microsatellite markers suggested that the island populations (except Kouzushima) were founded sequentially from the closest Ohshima to remote Niijima and Miyakejima during or before the penultimate interglacial period. Secondary gene flow from the source population was rare and occurred only for the closest (Ohshima) population. In addition, we found that an amino acid mutation in the Agouti signalling protein gene (Asip) was associated with coat colour variation among the island populations. The mutation was rare in the source population but completely fixed in the Miyakejima population. The phenotypic and genetic variation suggested that severe reduction of genetic variation and changes in allele frequency as a result of sequential colonization (i.e. the founder effect) had significant effects on colour polymorphism. The findings of the present study suggest that the founder effect, in addition to natural selection, facilitated the morphological changes below the species level over a relatively long time scale. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113 , 522–535.     

The Role of DNA Methylation Reprogramming During Sex Determination and Transition in Zebrafish

DNA methylation is a prevalent epigenetic modification in vertebrates, and it has been shown to be involved the regulation of gene expression and embryo development. However, it remains unclear how DNA methylation regulates sexual development, especially in species without sex chromosomes. To determine this, we utilized zebrafish to investigate DNA methylation reprogramming during juvenile germ cell development and adult female-to-male sex transition.We reveal that primordial germ cells(PGCs) undergo significant DNA methylation reprogramming during germ cell development, and the methylome of PGCs is reset to an oocyte/ovary-like pattern at 9 days post fertilization(9 dpf). When DNA methyltransferase(DNMT) activity in juveniles was blocked after 9 dpf, the zebrafish developed into females. We also show that Tet3 is involved in PGC development. Notably, we find that DNA methylome reprogramming during adult zebrafish sex transition is similar to the reprogramming during the sex differentiation from 9 dpf PGCs to sperm. Furthermore, inhibiting DNMT activity can prevent the female-to-male sex transition, suggesting that methylation reprogramming is required for zebrafish sex transition. In summary, DNA methylation plays important roles in zebrafish germ cell development and sexual plasticity.     

Origin of agouti-melanistic polymorphism in Wild Black Rats (Rattus rattus) inferred from Mc1r gene sequences

We examined nucleotide changes that underlie coat color variation in Black Rats (the Rattus rattus species complex), which show polymorphism in dorsal fur color, including either grayish brown (agouti) or black (melanistic) forms. We examined the full coding sequence of a gene known to produce melanism in other vertebrates-melanocortin-1-receptor gene Mc1r (954 bp) -using samples of both R. rattus (with 2n = 38) and its close relative Asian Black Rat (R. tanezumi; 2n = 42). We used 61 specimens from Japan with karyotype-known individuals and four samples from Pakistan. We found 11 allele sequences and constructed a network tree that shows two distinct clusters, with allelic segregation according to karyotype and by inference, representing the two species. We found that a nucleotide substitution from G to A at site 280, producing an amino acid change from glutamic acid to lysine, was associated with the dominant trait of the melanistic form of the coat color in R. rattus. Notably, the derived SNP 280A was found in a single allele, with the ancestral SNP 280G present in seven alleles. By contrast, all three alleles for R. tanezumi retain the ancestral SNP 280G. These results suggest a possible recent origin of melanism in R. rattus.     

Induction of oligodendrocyte differentiation from adult human fibroblast-derived induced pluripotent stem cells

Induced pluripotent stem cells (iPSCs) prepared from somatic cells might become a novel therapeutic tool in regenerative medicine, especially for the central nervous system (CNS). In this study, we attempted to induce O4-positive (O4⁺) oligodendrocytes from adult human fibroblast-derived iPSCs in vitro. We used two adult human iPSC cell lines, 201B7 and 253G1. 201B7 was induced by four-gene transduction (oct4, sox2, klf4, c-myc), and 253G1 was induced by three-gene transduction (oct4, sox2, klf4). We treated these cells with two in vitro oligodendrocyte-directed differentiation protocols that were optimized for human embryonic stem cells. One protocol used platelet-derived growth factor as the major mitogen for oligodendrocyte lineage cells, and the other protocol used epidermal growth factor (EGF) as the mitogen. Although the differentiation efficiency was low (less than 0.01%), we could induce O4⁺ oligodendrocytes from 253G1 cells using the EGF-dependent differentiation protocol. This is the first report of the in vitro induction of oligodendrocytes differentiation from human iPSCs.     

Possible role of LRP1, a CCN2 receptor, in chondrocytes

Low density lipoprotein receptor (LDLR)-related protein 1 (LRP1/CD91) is one of the receptors of CCN2 that conducts endochondral ossification and cartilage repair. LRP1 is a well-known endocytic receptor, but its distribution among chondrocytes remains to be elucidated. We herein demonstrate for the first time that the distribution of LRP1 in chondrocytes except for hypertrophic chondrocytes in vivo and in vitro. Interestingly, the LRP1 levels were higher in mature chondrocytic HCS-2/8 and osteoblastic SaOS-2 than in other cells, whereas the other LDLR family members involved in ossification were detected at lower levels in HCS-2/8. It was interesting to note that in HCS-2/8, LRP1 was observed not only on the cell surface and in the cytoplasm, but also in the nucleus. Exogenously added CCN2 was incorporated into HCS-2/8, which was partially co-localized with LRP1, and targeted to the recycling endosomes and nucleus as well as the lysosomes. These findings suggest specific roles of LRP1 in cartilage biology.     

Molecular cloning of cDNA encoding a ubiquitin-activating enzyme (E1) from goldfish (Carassius auratus) and expression analysis of the cloned gene

Destruction of cyclin B is required to the mitotic and meiotic cycles. A cyclin-specific ubiquitinating system, including ubiquitin-activating enzyme (E1), is thought to be responsible for cyclin B destruction. Here we present the cloning, sequencing and expression analysis of goldfish, Carassius auratus, E1 from goldfish ovary. The cloned cDNA is 4069 bp long and encodes 1059 amino acids. The deduced amino acid sequence is highly homologous to E1 from other species. Recombinant goldfish E1 could transfer ubiquitin to cyclin-selective ubiquitin-conjugating enzyme. Tissue distribution revealed a single 4.0-kb message ubiquitous among tissues.     

Long-term culture of purified postnatal oligodendrocyte precursor cells. Evidence for an intrinsic maturation program that plays out over months

Oligodendrocytes myelinate axons in the vertebrate central nervous system (CNS). They develop from precursor cells (OPCs), some of which persist in the adult CNS. Adult OPCs differ in many of their properties from OPCs in the developing CNS. In this study we have purified OPCs from postnatal rat optic nerve and cultured them in serum-free medium containing platelet-derived growth factor (PDGF), the main mitogen for OPCs, but in the absence of thyroid hormone in order to inhibit their differentiation into oligodendrocytes. We find that many of the cells continue to proliferate for more than a year and progressively acquire a number of the characteristics of OPCs isolated from adult optic nerve. These findings suggest that OPCs have an intrinsic maturation program that progressively changes the cell's phenotype over many months. When we culture the postnatal OPCs in the same conditions but with the addition of basic fibroblast growth factor (bFGF), the cells acquire these mature characteristics much more slowly, suggesting that the combination of bFGF and PDGF, previously shown to inhibit OPC differentiation, also inhibits OPC maturation. The challenge now is to determine the molecular basis of such a protracted maturation program and how the program is restrained by bFGF.