Molecular genetic diversity of the Saccharomyces yeasts in Taiwan: Saccharomyces arboricola, Saccharomyces cerevisiae and Saccharomyces kudriavzevii

Genetic hybridization, sequence and karyotypic analyses of natural Saccharomyces yeasts isolated in different regions of Taiwan revealed three biological species: Saccharomyces arboricola, Saccharomyces cerevisiae and Saccharomyces kudriavzevii. Intraspecies variability of the D1/D2 and ITS1 rDNA sequences was detected among S. cerevisiae and S. kudriavzevii isolates. According to molecular and genetic analyses, the cosmopolitan species S. cerevisiae and S. kudriavzevii contain local divergent populations in Taiwan, Malaysia and Japan. Six of the seven known Saccharomyces species are documented in East Asia: S. arboricola, S. bayanus, S. cerevisiae, S. kudriavzevii, S. mikatae, and S. paradoxus.     

Further study on the role of HSP70 on Ca2+ homeostasis in rat ventricular myocytes subjected to simulated ischemia

We hypothesized that activation of heat shock protein 70 (HSP70) by preconditioning, which is known to confer delayed cardioprotection, attenuates the impaired handling of Ca²⁺ at multiple sites. To test the hypothesis, we determined how the ryanodine receptor (RyR), sarco(endo)plasmic reticulum Ca²⁺-ATPase (SERCA), and Na⁺/Ca²⁺ exchanger (NCX) handled Ca²⁺ in rat ventricular myocytes preconditioned with a -opioid receptor agonist, U50488H (UP), followed by blockade of HSP70 with a selective antisense oligonucleotide and subsequently subjected to simulated ischemia. We determined the following: 1) the Ca²⁺ transients induced by electrical stimulation and caffeine, which provide the overall picture of Ca²⁺ homeostasis; 2) expression of RyR, SERCA, and NCX; and 3) Ca²⁺ fluxes via NCX by the use of ⁴⁵Ca²⁺ in the rat ventricular myocyte. We found that UP increased the activity of RyR, SERCA, and NCX and the expression of RyR and SERCA. These effects led to increases in the release of Ca²⁺ from the sarcoplasmic reticulum via RyR and in the removal of Ca²⁺ from the cytoplasm by reuptake of Ca²⁺ to the SR via SERCA and by extrusion of Ca²⁺ out of the cell via NCX. UP also reduced mitochondrial Ca²⁺ accumulation. All of the effects of UP were either abolished or significantly attenuated by blockade of HSP70 synthesis with a selective antisense oligonucleotide. The results are evidence that activation of HSP70 by preconditioning improves the ischemia-impaired Ca²⁺ homeostasis at multiple sites in the heart, which may be responsible, at least partly, for attenuated Ca²⁺ overload, improved recovery in contractile function, and cardioprotection. intracellular Ca²⁺, -opioid receptor; Na⁺/Ca²⁺ exchanger; ryanodine receptor; sarco(endo)plasmic reticulum Ca²⁺-ATPase     

Effect of vegetation cover on the abundance and diversity of ladybirds (Coccinellidae) assemblages in a peat bog

Predaceous ladybirds are important natural enemies of many insect pests in terrestrial ecosystems such as peatlands, which are habitats for specialized cold-adapted plants. Ladybird assemblages of pristine peat bogs have not yet been assessed. In total, 15 ladybird species were recorded in peat bog in Belarus by using entomological sweep net. The present study shows low diversity, evenness and species richness of ladybird assemblages. However, a small number of species were present in high numbers. These are Coccinella hieroglyphica, Chilocorus bipustulatus, Coccinulla qutuordecimpustulata and Hippodamia tredecimpunctata. Ladybird abundance was positively related to shrub cover and number of vascular plant species, and negatively related to herb cover. In terms of ladybird diversity, only shrub cover had a significant negative effect.     

Effect of Aromatic Compounds on Cellular Fatty Acid Composition of Rhodococcus opacus

In cells of Rhodococcus opacus GM-14, GM-29, and 1CP, the contents of branched (10-methyl) fatty acids increased from 3% to 15 to 34% of the total fatty acids when the cells were grown on benzene, phenol, 4-chlorophenol, chlorobenzene, or toluene as the sole source of carbon and energy, in comparison with cells grown on fructose. In addition, the content of trans-hexadecenoic acid increased from 5% to 8 to 18% with phenol or chlorophenol as the carbon source. The 10-methyl branched fatty acid content of R. opacus GM-14 cells increased in a dose-related manner following exposure to phenol or toluene when toluene was not utilized as the growth substrate. The results suggest that 10-methyl branched fatty acids may participate in the adaptation of R. opacus to lipophilic aromatic compounds.     

Highly reduced mass loss rates and increased litter layer in radioactively contaminated areas

The effects of radioactive contamination from Chernobyl on decomposition of plant material still remain unknown. We predicted that decomposition rate would be reduced in the most contaminated sites due to an absence or reduced densities of soil invertebrates. If microorganisms were the main agents responsible for decomposition, exclusion of large soil invertebrates should not affect decomposition. In September 2007 we deposited 572 bags with uncontaminated dry leaf litter from four species of trees in the leaf litter layer at 20 forest sites around Chernobyl that varied in background radiation by more than a factor 2,600. Approximately one quarter of these bags were made of a fine mesh that prevented access to litter by soil invertebrates. These bags were retrieved in June 2008, dried and weighed to estimate litter mass loss. Litter mass loss was 40 % lower in the most contaminated sites relative to sites with a normal background radiation level for Ukraine. Similar reductions in litter mass loss were estimated for individual litter bags, litter bags at different sites, and differences between litter bags at pairs of neighboring sites differing in level of radioactive contamination. Litter mass loss was slightly greater in the presence of large soil invertebrates than in their absence. The thickness of the forest floor increased with the level of radiation and decreased with proportional loss of mass from all litter bags. These findings suggest that radioactive contamination has reduced the rate of litter mass loss, increased accumulation of litter, and affected growth conditions for plants.     

MDA-MB-435 human breast carcinoma cell homo- and heterotypic adhesion under flow conditions is mediated in part by Thomsen-Friedenreich antigen-galectin-3 interactions

The importance of Thomsen-Friedenreich antigen (T antigen)-galectin-3 interactions in adhesion of human breast carcinoma cells to the endothelium under conditions of flow was studied. Highly metastatic cells (MDA-MB-435) expressing high levels of both galectin-3 and T antigen demonstrated significantly increased adhesion to monolayers of endothelial cells compared with their non-metastatic counterpart (MDA-MB-468) in vitro. Within minutes of adhesion, the highly metastatic cells acquire the ability of enhanced homotypic adhesion, leading to the formation of multicellular aggregates at sites of attachment to endothelial cells in vitro. Treatment of cells with lactulosyl-l-leucine, a synthetic T antigen antagonist that targets galectin-3 by mimicking T antigen, caused a 60-80% inhibition of both homo- and heterotypic adhesion of MDA-MB-435 cells. Confocal microscopy and fluorescence-activated cell sorter analysis revealed redistribution of endothelial galectin-3 to the site of heterotypic intercellular contacts, whereas galectin-3 in MDA-MB-435 cells accumulated at sites of homotypic interaction. MDA-MB-435 cells also exhibited increased adhesion and intravascular retention within the microvessels of transplanted lung allografts in nude mice. T antigen and galectin-3-mediated interactions of metastatic cancer cells with endothelium under conditions of flow are characterized by a unique adhesion mechanism that qualitatively distinguishes their homo- and heterotypic adhesive behavior from other cell types such as leukocytes.     

Ribosomal DNA sequencing and reinstatement of the genus Arthroascus von Arx

Sequence analysis of the D1/D2 domain of 26S rDNA was conducted upon seven Arthroascus strains from different geographic localities. The European and Asian species Arthroascus schoenii was documented from the North-American continent and from the Island of Hawaii. We discuss the heterogeneity of the genus Saccharomycopsis sensu Kurtzman and Robnett 1995. On the basis of molecular and genetic data the genus Arthroascus von Arx is reinstated.     

Molecular-genetic differentiation of the dairy yeast Kluyveromyces lactis and its closest wild relatives

The currently accepted formal division of the species Kluyveromyces lactis into two taxonomic varieties, Kl. lactis var. lactis and Kl. lactis var. drosophilarum, is based arbitrarily on phenotypic and ecological characters. On the other hand, the genetic hybridisation analysis and molecular karyotyping of its synonyms allowed us [FEMS Yeast Res. 2 (2002) 39] to reinstate them in the genus Zygofabospora Kudriavzev emend G. Naumov (=Kluyveromyces Kurtzman et al., 2001) as the varieties Zf. lactis var. lactis, Zf. lactis var. krassilnikovii, Zf. lactis var. drosophilarum, Zf. lactis var. phaseolospora and Zf. lactis var. vanudenii. In the present work, we studied forty Kl. lactis strains of different geographic and ecological origins by means of restriction analysis of the PCR-amplified non-coding nrDNA regions encompassing the intergenic spacer 2 (IGS2) and the internal transcribed spacers (ITS1 and ITS2). The results confirmed the complex structure of Kl. lactis. Moreover, four additional genetic populations were identified: three in North America ('aquatic', 'pseudovanudenii' and 'new') and one in Far-East Asia ('oriental'). Comparative sequence analysis of the 5.8S-rRNA gene and the two internal transcribed spacers revealed that the populations 'aquatic' and 'oriental' formed distinct taxa which are phylogenetically separate from the five known populations. However, some discrepancies were observed between the restriction and sequencing data. Genetic hybridisation analysis needs to be done to further elucidate the genetic relationships between the populations of Kl. lactis.