Molecular expression of Ly6k, a putative glycosylphosphatidyl-inositol-anchored membrane protein on the mouse testicular germ cells

Claudin 1 is one of the tight junctional proteins involved in the tight sealing of the cellular sheets and plays a crucial role in the maintenance of cell polarity. Although its structure and physiological function in intercellular adhesion is relatively well understood, we have little information about its possible involvement in early development of vertebrates. We found Xclaudin 1 is expressed maternally in the oocyte of Xenopus laevis and the zygotic expression initiates stage 9 in the animal hemisphere but not in the vegetal hemisphere, limited on the ectoderm and mesoderm until the end of gastrulation. We have investigated a potential role for claudin 1 at gastrulation by gain and loss-of-function studies. Over-expression of Xclaudin 1 resulted in gastrulation defect in a dose-dependent manner. Knockdown of Xclaudin 1 by antisense morpholino oligonucleotides (MOs) blocked convergent extension, whereas ectopic expression of Xclaudin 1-myc mRNA rescued these defects. However, altered expression of Xclaudin 1 did not inhibit mesodermal gene expression. Taken together, our results suggest that Xclaudin 1 is required for proper convergent extension movement during Xenopus gastrulation.     

Oxidative stress-induced apoptosis is mediated by ERK1/2 phosphorylation

Oxidative stress is known to induce apoptosis in a wide variety of cell types, apparently by modulating intracellular signaling pathways. High concentrations of H2O2 have been found to induce apoptosis in L929 mouse fibroblast cells. To elucidate the mechanisms of H2O2-mediated apoptosis, ERK1/2, p38-MAPK, and JNK1/2 phosphorylation was examined, and ERK1/2 and JNK1/2 were found to be activated by H2O2. Inhibition of ERK1/2 activation by treatment of L929 cells with PD98059 or dominant-negative ERK2 transfection blocked H2O2-induced apoptosis, while inhibition of JNK1/2 by dominant-negative JNK1 or JNK2 or MKK4 or MKK7 transfection did not affect H2O2-mediated apoptosis. H2O2-mediated ERK1/2 activation was not only Ras-Raf dependent, but also both tyrosine kinase (PDGFbeta receptor and Src) and PKCdelta dependent. H2O2-mediated PKCdelta-dependent and tyrosine kinase-dependent ERK1/2 activations were independent from each other. Based on the above results, we suggest for the first time that oxidative damage-induced apoptosis is mediated by ERK1/2 phosphorylation which is not only Ras-Raf dependent, but also both tyrosine kinase and PKCdelta dependent.     

Cloning, heterologous expression and purification of an isocitrate lyase from Streptomyces clavuligerus NRRL 3585.

The glyoxylate cycle comprising isocitrate lyase (ICL) and malate synthase (MS) is an anaplerotic pathway essential for growth on acetate as the sole carbon source. The aceB gene, which encodes malate synthase has been previously cloned from Streptomyces clavuligerus NRRL 3585 and characterized. In this study, the aceA gene, encoding ICL from S. clavuligerus NRRL 3585, was obtained via genome walking experiments and PCR. The fully sequenced open reading frame encodes 436 amino acids with a deduced M(r) of 47.5 kDa, consistent with the observed M(r) (49-67.5 kDa) of most ICL enzymes reported so far. The cloned aceA gene was expressed in Escherichia coli BL21(lambdaDE3) cells, from which ICL was purified as a His-tagged product and its functionality demonstrated. Furthermore, the relationship between the carbon sources, growth and ICL activity in S. clavuligerus were investigated. Rapid growth was observed when the cells were cultured on 0.5% (w/v) glycerol, while delayed growth was observed when cells were grown on 0.5% (w/v) acetate. However, in both cases, high levels of ICL activity coincided with a cessation of growth, suggesting a late physiological role played by ICL in the natural host, S. clavuligerus.     

Contact zone of two different chloroplast lineages and genetic guidelines for seed transfer in Quercus serrata and Quercus crispula

Within their natural distribution ranges, plant species exhibit a genetic structure that has been created by global climate change and natural selection over long periods. This genetic structure needs to be conserved for sustainable use of genetic resources. To conserve local forests with different genetic structures, genetic guidelines for seed and seedling transfer in individual species are necessary. Genetic guidelines have been published for 43 Japanese tree species using population genetic data; however, for practical use, more detailed genetic borders between important genetic lineages should be clarified to inform seed collection and planting. Thus, we investigated in detail the genetic borders between two important Japanese oak species, Quercus serrata and Quercus crispula, in the Chubu region of Japan using chloroplast and nuclear DNA markers, and we discuss the factors that influenced border creation using the results of species distribution modeling (SDM). The chloroplast DNA (cpDNA) haplotype was clearly different within the Chubu region of Japan but the difference in nuclear DNA between northern and southern haplotype populations was very small, both in Q. serrata and Q. crispula. The results of SDM showed that during the last glacial maximum (LGM) Q. serrata was distributed mostly along the coastline but Q. crispula was distributed not only along the coast but also in mountainous areas further inland. The cpDNA genetic borders of these two oak species are complex and seem to have been influenced by topography and their distribution during the LGM. We propose and discuss genetic guidelines for these two oak species based on the results of this study.     

Cadmium uptake via apoplastic bypass flow in Oryza sativa

Journal of Plant Research - It is known that rice roots take up cadmium (Cd) via the symplastic route mediated by membrane-bound mineral transporters. Here we provide evidence that apoplastic...     

Population differentiation and gene flow within a metapopulation of a threatened tree, Magnolia stellata (Magnoliaceae)

We examined genetic differentiation among eight local populations of a metapopulation of Magnolia stellata using 10 nuclear and three chloroplast microsatellite (nSSR and cpSSR) markers and evaluated the influence of historical gene flow on population differentiation. The coefficient of genetic differentiation among populations for nSSR (F(ST) = 0.053) was less than half that for cpSSR (0.137). An isolation-by-distance pattern was detected for nSSRs, but not cpSSRs. These results suggest that pollen flow, as well as seed dispersal, has significantly reduced genetic differentiation among populations. We also examined patterns of contemporary pollen flow by paternity analysis of seeds from nine seed parents in one of the populations using the nSSR markers and found it to be greatly restricted by the distance between parents. Although most pollen flow occurred within the population, pollen flow from outside the population accounted for 2.5% of the total. When historical and contemporary pollen flows among populations were compared, the levels of pollen flow seem to have declined recently. We conclude that to conserve M. stellata, it is important to preserve the whole population by maintaining its metapopulation structure and the gene flow among its populations.     

Development of multidrug resistance type I Cmdr1 expression in chicken embryonic gonads

A primary role of P-glycoprotein (P-gp), encoded by the multidrug resistance type I gene, is to protect against naturally occurring xenotoxics. Recently, the preferential expression of chicken multidrug resistance type I (Cmdr1) was identified in the embryonic gonads during the early periods of development. Here we investigated the expression of Cmdr1 and P-gp in the gonads during embryogenesis, and compared to that in the ovarian follicles of domestic hens (Gallus gallus). As revealed by immunohistochemistry, P-gp was highly expressed in theca cells of mature follicles, whereas the expression was low in immature follicles. Immunohistochemical analysis showed that expression of Cmdr1-type P-gp was very low in embryonic gonads. Cmdr1 mRNA was undetectable in the gonads of 5-day embryos (E5) by RT-PCR, whereas Cmdr1 mRNA was significantly detectable in the developing gonads at E9 and E21. In the testicular tissues, germ cells were distributed along developing seminiferous cords as identified by a specific marker gene, whereas Cmdr1-type P-gp positive cells were observed evenly on testicular tissues. Collectively, it is concluded that Cmdr1 expression is initiated in the chicken ovary and testis after sexual differentiation, but expression of Cmdr1-type P-gp is very low through embryogenesis.     

An efficient conversion of carboxylic acids to one-carbon degraded aldehydes via 2-hydroperoxy acids

After the formation of dianions of a carboxylic acid with lithium diisopropylamide, oxygen was bubbled into the solution to produce 2-hydroperoxy acid. Then the reaction mixture was acidified with a 2 N HCl solution and subsequently elevated to 50 degrees C to afford the aldehyde with the loss of one carbon atom. Even saturated (C(10)-C(20)) and unsaturated (C(18:1)) carboxylic acids were converted into the odd aldehydes (C(9)-C(19), C(17:1)) in high yields. This conversion was found to be an efficient method for the preparation of carboxylic acids (Cn) to one-carbon degraded aldehydes (Cn-1) via 2-hydroperoxy acids.