Evolution of local adaptations in dispersal strategies

The optimal probability and distance of dispersal largely depend on the risk to end up in unsuitable habitat. This risk is highest close to the habitat's edge and consequently, optimal dispersal probability and distance should decline towards the habitat's border. This selection should lead to the emergence of spatial gradients in dispersal strategies. However, gene flow caused by dispersal itself is counteracting local adaptation. Using an individual based model we investigate the evolution of local adaptations of dispersal probability and distance within a single, circular, habitat patch. We compare evolved dispersal probabilities and distances for six different dispersal kernels (two negative exponential kernels, two skewed kernels, nearest neighbour dispersal and global dispersal) in patches of different size. For all kernels a positive correlation between patch size and dispersal probability emerges. However, a minimum patch size is necessary to allow for local adaptation of dispersal strategies within patches. Beyond this minimum patch area the difference in mean dispersal distance between center and edge increases linearly with patch radius, but the intensity of local adaptation depends on the dispersal kernel. Except for global and nearest neighbour dispersal, the evolved spatial pattern are qualitatively similar for both, mean dispersal probability and distance. We conclude, that inspite of the gene-flow originating from dispersal local adaptation of dispersal strategies is possible if a habitat is of sufficient size. This presumably holds for any realistic type of dispersal kernel.     

Diversity analysis of dairy and non-dairy strains of Lactococcus lactis ssp. lactis by multilocus sequence analysis (MLSA)

The genetic diversity of 31 identified strains of Lactococcus lactis ssp. lactis isolated from different dairy and non-dairy sources were investigated at gene level using multilocus sequence analysis (MLSA) and PCR-RFLP based on the differences in four selected partial protein coding gene sequences: araT, encoding aromatic amino acid-specific aminotransferase; dtpT, encoding di/tri peptide transporter; yueF, encoding non-proteolytic protein, peptidase, M16 family; and pdhA, encoding pyruvate dehydrogenase E1 component α-subunit. A set of seven test strains from different isolation sources and one reference strain, L. lactis ssp. lactis NCDC 094, were analyzed by MLSA. The strains showed distinct diversity among themselves and exhibited a greater percent similarity with reference strains L. lactis ssp. lactis CV56 (CP002365.1), IL1403 (AE005176.1), and KF147 (CP001834.1) in comparison with L. lactis ssp. cremoris NZ9000 (CP002094.1), MG1363 (AM406671.1), and SK11 (CP00425.1). The MLSA revealed one distinct genomic lineage within strains exclusively of L. lactis ssp. lactis. This analysis also revealed no source-wise genetic relationship in the test strains analyzed. Further, PCR-RFLP of araT, dtpT, yueF and pdhA also characterized the single genomic lineage exclusively of L. lactis ssp. lactis within a total of 24 test strains.     

Thermophilic bacteria that tolerate a wide temperature and pH range colonize the Soldhar (95 °C) and Ringigad (80 °C) hot springs of Uttarakhand,India

Twenty-eight bacterial cultures, isolated from hot springs in Uttarakhand, were characterized with particular reference to their wide temperature and pH tolerance and production of enzymes in the thermophilic range. All the bacterial isolates were observed as Gram-positive or variable rods in varied arrangement. Bacterial isolates exhibited tolerance to a wide temperature range (20–80 °C), from mesophilic (+11° to +45 °C) to thermophilic (+46 ° to +75 °C); few almost reached the hyperthermophilic range (+76 °C). The isolates also tolerated a wide pH range (4–14) and moderate salt concentration. The optimum growth of the bacterial isolates was observed at 55 °C and 7 pH. Out of 28 isolates, 25 produced lipase, 25 amylase, 24 cellulase, 22 protease and 13 xylanase at 55 and 65 °C. Tolerance to a wide temperature and pH range and the production of enzymes in a thermophilic temperature range can be considered as indicators of ecological competence of these bacterial isolates for colonizing the high temperature environment. On the basis of 16S rDNA similarity, 20 bacterial isolates belonged to Bacillus licheniformis, five to Paenibacillus ehimensis and one each to Bacillus sonorensis, B. tequilensis, and Staphylococcus epidermidis. Besides variation in phenotypic characters, strains of B. licheniformis and P. ehimensis showed varying 16S rDNA similarity between 97–99 % and 95–99 %, respectively. Consideration of temperature preferences in classifying microorganisms on the basis of their minimum, maximum, and optimum growth requirements is also discussed. The study has ecological relevance in the context of colonization of high temperature environments by thermophilic bacteria.     

Mapping of the dopa decarboxylase gene to the 11A band of the murine genome.

A human DOPA decarboxylase (DDC) cDNA probe of 747 base pairs has been used to map the DDC gene by in situ hybridization on mouse metaphase chromosomes. This result indicates that the gene is located on band 11A, near the erythroblastosis oncogene B (erb b) locus. This provides evidence for a synteny group on mouse chromosome 11 and human chromosome 7.     

Extraction of crystal violet-iodine complex from gram positive bacteria by different solvents and its implication on gram differentiation

Summary Crystal violet from Gram stained S. aureus can be extracted completely by 95% ethanol if the stained bacteria is pre-treated with dilute sodium thiosulphate solution. Thiosulphate removes iodine form the cell component-dye-iodine complex instantaneously and renders the dye extractable by the differentiating medium. 11 alcoholic solutions of aniline, dimethyl aniline, nitro-benzene, benzene, toluene or xylol can also extract the color from the stained S. aureus; the extraction with the first three solvents is almost exhaustive while with the latter solvents extraction is appreciable but incomplete. These solvents can form charge-transfer complexes with iodine. The findings indicate that the stability of the cell component-dye-iodine complex determines the Gram-character of the cell. A model hasbeen presented for the Gram cell component-dye-iodine complex.     

D1/D2 domain of large-subunit ribosomal DNA for differentiation of Orpinomyces spp

This study presents the suitability of D1/D2 domain of large-subunit (LSU) ribosomal DNA (rDNA) for differentiation of Orpinomyces joyonii and Orpinomyces intercalaris based on PCR-restriction fragment length polymorphism (RFLP). A variation of G/T in O. intercalaris created an additional restriction site for AluI, which was used as an RFLP marker. The results demonstrate adequate heterogeneity in the LSU rDNA for species-level differentiation.     

The Na,K-ATPase alpha4 gene (Atp1a4) encodes a ouabain-resistant alpha subunit and is tightly linked to the alpha2 gene (Atp1a2) on mouse chromosome 1.

We have isolated and characterized cDNA clones encoding the murine homologue of a putative fourth Na,K-ATPase alpha subunit isoform (alpha4). The predicted polypeptide is 1032 amino acids in length and exhibits 75% amino acid sequence identity to the rat alpha1, alpha2, and alpha3 subunits. Within the first extracellular loop, the alpha4 subunit is highly divergent from other Na,K-ATPase alpha subunits. Because this region of Na,K-ATPase is a major determinant of ouabain sensitivity, we tested the ability of the rodent alpha4 subunit to transfer ouabain resistance in a transfection protocol. We find that a cDNA containing the complete rodent alpha4 ORF is capable of conferring low levels of ouabain resistance upon HEK 293 cells, an indication that the alpha4 subunit can substitute for the endogenous ouabain-sensitive alpha subunit of human cells. Nucleotide sequences specific for the murine alpha4 subunit were used to identify the chromosomal position of the alpha4 subunit gene. By hybridizing an alpha4 probe with a series of BACs, we localized the alpha4 subunit gene (Atp1a4) to the distal portion of mouse chromosome 1, in very close proximity to the murine Na,K-ATPase alpha2 subunit gene. In adult mouse tissues, we detected expression of the alpha4 subunit gene almost exclusively in testis, with low levels of expression in epididymis. The close similarities in the organization and expression pattern of the murine and human alpha4 subunit genes suggest that these two genes are orthologous. Together, our studies indicate that the alpha4 subunit represents a functional Na,K-ATPase alpha subunit isoform.     

Spore production of Penicillium roqueforti by solid state fermentation: Stoichiometry, growth and sporulation behavior

The development of Penicillium roqueforti on buckwheat seeds proceeds roughly into four steps, involving a lag phase and three growth phases. First, it appears as a spore germination and external colonization of the grains by the mycelium. Then, mainly external sporulation and internal colonization of the seeds occur and finally internal sporulation takes place. The Stoichiometry of the growth and the sporulation is established. Kinetic experiments performed in a fixed bed reactor show that the growth of the microorganism (biomass production) may be estimated by the protein content of the medium. This growth occurs with a very low mu(max) value close to 0.030 h(-1). The chitin content of the medium is an indicator of the sporulation, just as the metabolic liquor (mainly water) produced during the course of a cultivation. The values of the observed respiratory quotient are close to those predicted by stoichiometry.     

Molecular aspects of the inactivation of tryptophanyl transfer ribonucleic acid synthetase by N-ethylmaleimide.

The tryptic maps of tryptophanyl-tRNA synthetase from beef pancreas show that the 8 cysteinyl residues of the enzyme subunit are located, 2 by 2, on four different peptides. The kinetics of the incorporation of radioactivity from N-[ethyl-14C]ethylmaleimide into these peptides are compared in this paper with the kinetics of the changes of the catalytic properties of the enzyme occurring during alkylation. This comparison allows the identification of (a) the peptide carrying the cysteinyl residues located on the surface of the molecule, (b) the peptide carrying the deeply buried residues unmasked by the dissociation of the subunits, and (c) the peptide carrying the --SH group located in the vicinity of the binding site of tryptophan. The fourth peptide is shown to have a great sensitivity to pH with respect to the reactivity of its cysteinyl residues toward N-ethylmaleimide. The same unusual pH dependence is found for the rate of quenching of the intrinsic fluorescence of the protein during the alkylation, suggesting a strong sensitivity of the conformation of tryptophanyl-tRNA synthetase to pH in the range of 7 to 9.