Evidence for Inbreeding and Genetic Differentiation among Geographic Populations of the Saprophytic Mushroom Trogia venenata from Southwestern China

During the past 40 years, more than 400 Sudden Unexplained Deaths (SUDs) have occurred in Yunnan, southwestern China. Epidemiological and toxicological analyses suggested that a newly discovered mushroom called Trogia venenata was the leading culprit for SUDs. At present, relatively little is known about the genetics and natural history of this mushroom. In this study, we analyzed the sequence variation at four DNA fragments among 232 fruiting bodies of T. venenata collected from seven locations. Our ITS sequence analyses confirmed that all the isolates belonged to the same species. The widespread presence of sequence heterozygosity within many strains at each of three protein-coding genes suggested that the fruiting bodies were diploid, dikaryotic or heterokaryotic. Within individual geographic populations, we found significant deviations of genotype frequencies from Hardy-Weinberg expectations, with the overall observed heterozygosity lower than that expected under random mating, consistent with prevalent inbreeding within local populations. The geographic populations were overall genetically differentiated. Interestingly, while a positive correlation was found between population genetic distance and geographic distance, there was little correlation between genetic distance and barium concentration difference for the geographic populations. Our results suggest frequent inbreeding, geographic structuring, and limited gene flow among geographic populations of T. venenata from southwestern China.     

A divergent lineage among Octopus minor (Sasaki, 1920) populations in the Northwest Pacific supported by DNA barcoding

Octopus minor (Sasaki, 1920) is an important economic fishery resource in China. In order to explore the stock information and the phylogeographic status of O. minor, mitochondrial DNA cytochrome c oxidase subunit I (COI, 565?bp) and 16S rRNA (493?bp) genes were amplified from 11 different sampling locations. Genetic diversity evaluated by haplotypic and nucleotidic diversity implied high diversity in Lianjiang, and relatively low diversity in Rongcheng, which suggests that effective measures to protect the O. minor resource in this area are urgently required. Private haplotypes and remarkable higher pairwise Φ_ST in Yilan are responsible for the deep genetic divergence between Yilan and the 10 other populations. Haplotypes networks and two clusters’ topological structure also support the distinct subgroups (lineages A and lineages B), which apparently possess smaller genetic variation than mean interspecies distance. Taiwan island and its strait may act as a natural barrier that restricts the gene flow from the mainland. Deep genetic divergence between mainland and Taiwanese east coasts suggests different genetic stock, indicating that different management strategies are required.     

Heritability of Eating Behavior Assessed Using the DEBQ (Dutch Eating Behavior Questionnaire) and Weight‐related Traits: The Healthy Twin Study

The heritability of eating behavior and body weight–related traits in Asian populations has not been reported. The purpose of this study was to estimate the heritability of eating behavior and the body weight–related traits of current weight and self‐reported past weight among twins and their families. Study subjects were 2,144 Korean, adult, same‐sex twins and their families at the ages between 20 and 65 years (443 monozygotic (MZ) and 124 dizygotic (DZ) twin pairs, and 1,010 individuals of their family). The Dutch Eating Behavior Questionnaire (DEBQ) was used to assess three eating behavior subscales measuring restraint, emotional eating, and external eating. A variance component approach was used to estimate heritability. After consideration of shared environmental effects and adjustment for age and sex effects, the heritability estimates ± s.e. among twins and their family members were 0.31 ± 0.036 for restraint, 0.25 ± 0.098 for emotional eating, 0.25 ± 0.060 for external eating, 0.77 ± 0.032 for measured current body weight, and 0.70 ± 0.051 for self‐reported weight at 20 years old. The three DEBQ subscales were associated with all weight related traits after adjustment for age and sex. These results suggest eating behaviors and weight‐related traits have a genetic influence, and eating behaviors are associated with obesity indexes. Our findings from Korean twin family were similar to those reported in Western populations.     

Long-term effects of postovulatory aging of mouse oocytes on offspring: a two-generational study.

Aims of this study were to analyze the long-term effects of postovulatory aging of mouse oocytes on 1) reproductive traits of parental (F(0)) and first (F(1))-generation females (pregnancy rate, gestation length, litter size, perinatal death, and sex ratio of offspring) and 2) developmental and behavioral variables of F(1) and second-generation (F(2)) offspring (birth weight and weight gain during preweaning development, postnatal day of attainment of immediate righting, spontaneous motor activity, and passive and active conditioned learning ability). Hybrid (C57BL/6JIco x CBA/JIco) females were artificially inseminated at 13 h (control group) or 22 h (oocyte-aged group) after GnRH injection. Experimental (oocyte-aged group) F(0) females exhibited lower pregnancy rate, shortened gestation length, decreased litter size, higher perinatal death of their pups, and increased percentage of male offspring compared to control F(0) females. Postovulatory aging of oocytes was also associated with increased number of growth-retarded pups, delayed development of the righting reflex, and higher spontaneous motor activity and emotionality of F(1) offspring. Postovulatory aging of F(0) oocytes did not affect birth weight, weight gain during preweaning development, passive and active conditioned learning ability of F(1) offspring, or reproductive traits of F(1) females or developmental and behavior variables of F(2) offspring.     

Caspase-2 Short Isoform Interacts with Membrane-Associated Cytoskeleton Proteins to Inhibit Apoptosis

Caspase-2 (casp-2) is the most conserved caspase across species, and is one of the initiator caspases activated by various stimuli. The casp-2 gene produces several alternative splicing isoforms. It is believed that the long isoform, casp-2L, promotes apoptosis, whereas the short isoform, casp-2S, inhibits apoptosis. The actual effect of casp-2S on apoptosis is still controversial, however, and the underlying mechanism for casp-2S-mediated apoptosis inhibition is unclear. Here, we analyzed the effects of casp-2S on DNA damage induced apoptosis through “gain-of-function” and “loss-of-function” strategies in ovarian cancer cell lines. We clearly demonstrated that the over-expression of casp-2S inhibited, and the knockdown of casp-2S promoted, the cisplatin-induced apoptosis of ovarian cancer cells. To explore the mechanism by which casp-2S mediates apoptosis inhibition, we analyzed the proteins which interact with casp-2S in cells by using immunoprecipitation (IP) and mass spectrometry. We have identified two cytoskeleton proteins, Fodrin and α-Actinin 4, which interact with FLAG-tagged casp-2S in HeLa cells and confirmed this interaction through reciprocal IP. We further demonstrated that casp-2S (i) is responsible for inhibiting DNA damage-induced cytoplasmic Fodrin cleavage independent of cellular p53 status, and (ii) prevents cisplatin-induced membrane blebbing. Taken together, our data suggests that casp-2S affects cellular apoptosis through its interaction with membrane-associated cytoskeletal Fodrin protein.     

Two independent growth factor-generated signals regulate c-fos and c-myc mRNA levels in Swiss 3T3 cells

Polypeptide growth factors that stimulate cell proliferation bind to cell surface receptors and activate intracellular signal transduction pathways. One major signalling pathway, initiated by phosphatidylinositol (PI) turnover, involves activation of protein kinase C. Some polypeptide growth factors, including mitogens that activate protein kinase C, induce a rapid increase in expression of the proto-oncogenes, c-myc and c-fos. In order to characterize the signal transduction pathways responsible for proto-oncogene activation, we treated Swiss 3T3 cells with the tumor promoter phorbol dibutyrate to generate cells deficient in protein kinase C. These cells were then stimulated with platelet extract, bombesin, or epidermal growth factor (EGF) and the levels of c-myc and c-fos mRNA were determined. Platelet extract or bombesin, which stimulate PI turnover, were substantially weaker inducers of c-myc and c-fos mRNA levels in the protein kinase C-depleted cells, although some variability with platelet extract was noted. EGF, which does not stimulate PI turnover in several cell systems, was by contrast a potent inducer of both proto-oncogenes whether or not the cells were deficient in protein kinase C. Pretreatment of cells with phorbol dibutyrate caused little or no change in the basal levels of c-myc or c-fos mRNA, but led to a small but significant increase in basal levels of ornithine decarboxylase mRNA. These results demonstrate that EGF and growth factors that activate PI turnover induce expression of the c-myc and c-fos proto-oncogenes through different pathways.     

Studies on hypothalamo-pituitary corticoliberin system. I. Localization of corticotropin-releasing factor (CRF)- and neurophysin-immunoreactive neurons in the Mongolian gerbil (Meriones unguiculatus)

The immunohistochemical localization of CRF- and neurophysin-containing neurons in the hypothalamus of the Mongolian gerbil was studied by means of the PAP technique. The CRF-immunoreactive fibers were detected mainly in the outer layer of the median eminence of intact adult male gerbils. The CRF-positive neurons respond to aminoglutethimide (Elipten, Ciba) administration by showing increased immunoreactivity and an increase in the number of stained cell bodies in the parvocellular division of the paraventricular nucleus. Aminoglutethimide treatment results also in an increase in the number of neurophysin-immunoreactive nervous fibers localized in the internal layer of the median eminence. However, CRF-immunoreactive fibers are observed mainly in the outer layer of the median eminence while neurophysin-immunopositive axons are seen predominantly in the internal layer of this region. Since the axons of paraventricular neurons run to the median eminence and their staining ability is changed due to aminoglutethimide, their involvement in the endocrine control of hypophysial ACTH release is postulated.     

Production of milk-clotting enzymes by basidiomycetes

BasidiomycetesPhellinus chrysoloma, Kuehneromyces mutabilis andGanoderma applanatum produce extracellular milk-clotting enzymes. The enzymes are acid proteinases stable at 40°C and within pH 3–5.5. Only the enzyme preparation fromP. chrysoloma exhibits properties comparable with animal chymosin.     

How M.MspI and M.HpaII decide which base to methylate.

The HpaII methylase (M.HpaII) recognizes the sequence CCGG and methylates the inner cytosine residue. The MspI methylase (MspI) recognizes the same sequence but methylates the outer cytosine residue. Both methylases have the usual architecture of 10 well-conserved motifs surrounding a variable region, responsible for sequence specific recognition, that is quite different in the two methylases. We have constructed hybrids between these two methylases and studied their methylation properties. A hybrid containing the variable region and C-terminal sequences from M.MspI methylates the outer cytosine residue. A second hybrid identical to the first except that the variable region derives from the M.HpaII methylates the inner cytosine residue. Thus the choice of base to be methylated within the recognition sequence is determined by the variable region.