Sexual and Aggressive Behaviour in Species Hybrids of Poecilia mexicana and Poecilia velifera (Pisces,Poeciliidae)

The inheritance of sexual behaviour patterns was studied in species hybrids of Poecilia mexicana and Poecilia velifera. In addition, the aggressive behaviour and some morphological characters have been investigated and checked for a possible correlation between and within these three different traits studied. All the characters are inherited polygenically. The minimum genetic factors could be estimated only for some characters.     

Phylogeny of the water strider genus Gerris Fabricius (Heteroptera: Gerridae) based on COI mtDNA, EF-1α nuclear DNA and morphology

Phylogenetic relationships between water striders (Heteroptera: Gerridae) of genus Gerris Fabricius were examined using molecular and morphological characters. The molecular dataset was 820 bp DNA from the 3′ half of the mitochondrial gene encoding cytochrome oxidase subunit I and 515 bp DNA from the nuclear gene encoding elongation factor 1 alpha. The morphological dataset was a slightly modified version of a previously published dataset. Representatives from all eight recognized species groups of Gerris, as well as six species from three related genera, including Gigantometra gigas, Limnoporus esakii, L. rufoscutellatus, Aquarius najas, A. conformis and A. paludum, were included. Unweighted parsimony analyses of the COI sequences gave a topology with strong support for only those nodes that were already recognized as closely related based on morphological characters. Similar analyses of EF‐1α gave a cladogram with a topology quite different from that based on morphology and COI. Unweighted parsimony analyses of the ‘total evidence’ dataset largely supports the traditional view of Gerris phylogeny. Finally, the implications of the reconstructed phylogeny in relation to biogeography and ecological phylogenetics of Gerris is discussed.     

Linkage disequilibrium for different scales and applications

Assessing the patterns of linkage disequilibrium (LD) has become an important issue in both evolutionary biology and medical genetics since the rapid accumulation of densely spaced DNA sequence variation data in several organisms. LD deals with the correlation of genetic variation at two or more loci or sites in the genome within a given population. There are a variety of LD measures which range from traditional pairwise LD measures such as D' or r2 to entropy-based multi-locus measures or haplotype-specific approaches. Understanding the evolutionary forces (in particular recombination) that generate the observed variation of LD patterns across genomic regions is addressed by model-based LD analysis. Marker type and its allelic composition also influence the observed LD pattern, microsatellites having a greater power to detect LD in population isolates than SNPs. This review aims to explain basic LD measures and their application properties.     

The<Emphasis Type="Italic"> Trox-2</Emphasis> Hox/ParaHox gene of<Emphasis Type="Italic"> Trichoplax</Emphasis> (Placozoa) marks an epithelial boundary

Hox and ParaHox genes are implicated in axial patterning of cnidarians and bilaterians, and are thought to have originated by tandem duplication of a single ProtoHox gene followed by duplication of the resultant gene cluster. It is unclear what the ancestral role of Hox/ParaHox genes was before the divergence of Cnidaria and Bilateria, or what roles the postulated ProtoHox gene(s) played. Here we describe the full coding region, spatial expression and function of Trox-2, the single Hox/ParaHox-type gene identified in Trichoplax adhaerens (phylum Placozoa) and either a candidate ProtoHox or a ParaHox gene. Trox-2 is expressed in a ring around the periphery of Trichoplax, in small cells located between the outer margins of the upper and lower epithelial cell layers. Inhibition of Trox-2 function, either by uptake of morpholino antisense oligonucleotides or by RNA interference, causes complete cessation of growth and binary fission. We speculate that Trox-2 functions within a hitherto unrecognized population of possibly multipotential peripheral stem cells that contribute to differentiated cells at the epithelial boundary of Trichoplax.Edited by D. Tautz     

The selenoprotein thioredoxin reductase is expressed in peripheral blood monocytes and THP1 human myeloid leukemia cells--regulation by 1,25-dihydroxyvitamin D3 and selenite

1,25(OH)2 Vitamin D3 (1,25(OH)2D3) and adhesion propagate monocyte differentiation. We identified the selenoprotein thioredoxin reductase (TrxR) as a new molecular target for 1,25(OH)2D3 in monocytes during this process. In THP1 monocytic leukemia cells 1,25(OH)2D3 stimulated TrxR mRNA levels 2-4-fold by 4-8 h and enhanced TrxR activity (60%) (as measured by the dithionitrobenzole-assay) after 24 h, which declined below baseline after 96 h. The addition of 100 nM selenite enhanced (approx. 50%) basal and stimulated enzyme activity in THP1 cells. The relative stimulation by 1,25(OH)2D3 was very similar but peak levels were sustained in THP1 cells up to 48 h. Human peripheral blood monocytes (PBM) of different donors showed very low basal TrxR steady state mRNA levels which were markedly enhanced (as analyzed by Northern blotting) after 4 h of adherence to culture dishes. 1,25(OH)2D3 (100 nM) further stimulated TrxR mRNA expression (4 h, 3-fold). TrxR enzyme activity mirrored the mRNA changes. Basal activity was stimulated approx. 25% by adhesion in culture alone and was further stimulated (approximately 15%) by 1,25(OH)2D3 after 4 h. By 24 h similar results were achieved but the effect of 1,25(OH)2D3 could be seen in the presence of 100 nM selenium only. The expression of TrxR and its regulation by 1,25(OH)2D3 and selenite in monocytes might be important for their induction of differentiation and maintenance of function.     

Identification of three cysteines as targets for the Zn2+ blockade of the human skeletal muscle chloride channel

Currents through the human skeletal muscle chloride channel hClC-1 can be blocked by external application of 1 mM Zn2+ or the histidine-reactive compound diethyl pyrocarbonate (DEPC). The current block by Zn2+ strongly depends on the external pH (pKa near 6.9), whereas the block by DEPC is rather independent of the pH in the range of 5.5 to 8.5. To identify the target sites of these reagents, we constructed a total of twelve cysteine- and/or histidine-replacement mutants, transfected tsA201 cells with them, and investigated the resulting whole-cell chloride currents. The majority of the mutants exhibited a similar sensitivity toward Zn2+ or DEPC as wild type (WT) channels. Block by 1 mM Zn2+ was nearly absent only with the mutant C546A. Four mutants (C242A, C254A, H180A, and H451A) were slightly less sensitive to Zn2+ than WT. Tests with double, triple, and quadruple mutants yielded that, in addition to C546, C242 and C254 are also most likely participating in Zn2+-binding.     

Near-infrared analysis of fennel (Foeniculum vulgare Miller) on different spectrometers--basic considerations for a reliable network

The aim of this study was to investigate the accuracy and transferability of near-infrared (NIR) calibrations for estimating the content and composition of the volatile fraction in fennel fruits (Foeniculum vulgare Miller) as an example of medicinal and spice plants. A master calibration with spectra obtained on a scanning monochromator was generated using 345 samples from three different harvests (1997-1999). A subset of 70 samples from 1999 was also measured on a dispersive grating and a scanning diode array system to gain an insight into the influence of sample presentation and scanning techniques. For all instruments, calibrations with standard errors in the range of the reference method were achieved. Furthermore the influence of storage on NIR spectra and, additionally, the potential of transferring spectra between both scanning monochromators was studied.     

Inhibition of myocardial injury by ischemic postconditioning during reperfusion: comparison with ischemic preconditioning

Ischemic preconditioning (Pre-con) is an adaptive response triggered by a brief ischemia applied before a prolonged coronary occlusion. We tested the hypothesis that repetitive ischemia applied during early reperfusion, i.e., postconditioning (Post-con), is cardio-protective by attenuating reperfusion injury. In anesthetized open-chest dogs, the left anterior descending artery (LAD) was occluded for 60 min and reperfused for 3 h. In controls (n = 10), there was no intervention. In Pre-con (n = 9), the LAD was occluded for 5 min and reperfused for 10 min before the prolonged occlusion. In Post-con (n = 10), at the start of reperfusion, three cycles of 30-s reperfusion and 30-s LAD reocclusion preceded the 3 h of reperfusion. Infarct size was significantly less in the Pre-con (15 +/- 2%, P < 0.05) and Post-con (14 +/- 2%, P < 0.05) groups compared with controls (25 +/- 3%). Tissue edema (% water content) in the area at risk was comparably reduced in Pre-con (78.3 +/- 1.2, P < 0.05) and Post-con (79.7 +/- 0.6, P < 0.05) versus controls (81.5 +/- 0.4). Polymorphonuclear neutrophil (PMN) accumulation (myeloperoxidase activity, Deltaabsorbance.min-1.g tissue-1) in the area at risk myocardium was comparably reduced in Post-con (10.8 +/- 5.5, P < 0.05) and Pre-con (13.4 +/- 3.4, P < 0.05) versus controls (47.4 +/- 15.3). Basal endothelial function measured by PMN adherence to postischemic LAD endothelium (PMNs/mm2) was comparably attenuated by Post-con and Pre-con (15 +/- 0.6 and 12 +/- 0.6, P < 0.05) versus controls (37 +/- 1.5), consistent with reduced expression of P-selectin on coronary vascular endothelium in Post-con and Pre-con. Endothelial function assessed by the maximal vasodilator response of postischemic LAD to acetylcholine was significantly greater in Post-con (104 +/- 6%, P < 0.05) and Pre-con (109 +/- 5%, P < 0.05) versus controls (71 +/- 8%). Plasma malondialdehyde (microM/ml), a product of lipid peroxidation, was significantly less at 1 h of reperfusion in Post-con (2.2 +/- 0.2, P < 0.05) versus controls (3.2 +/- 0.3) associated with a decrease in superoxide levels revealed by dihydroethidium staining in the myocardial area at risk. These data suggest that Post-con is as effective as Pre-con in reducing infarct size and preserving endothelial function. Post-con may be clinically applicable in coronary interventions, coronary artery bypass surgery, organ transplantation, and peripheral revascularization where reperfusion injury is expressed.     

Automated enumeration of groups of marine picoplankton after fluorescence in situ hybridization

We describe here an automated system for the counting of multiple samples of double-stained microbial cells on sections of membrane filters. The application integrates an epifluorescence microscope equipped with motorized z-axis drive, shutters, and filter wheels with a scanning stage, a digital camera, and image analysis software. The relative abundances of specific microbial taxa are quantified in samples of marine picoplankton, as detected by fluorescence in situ hybridization (FISH) and catalyzed reporter deposition. Pairs of microscopic images are automatically acquired from numerous positions at two wavelengths, and microbial cells with both general DNA and FISH staining are counted after object edge detection and signal-to-background ratio thresholding. Microscopic fields that are inappropriate for cell counting are automatically excluded prior to measurements. Two nested walk paths guide the device across a series of triangular preparations until a user-defined number of total cells has been analyzed per sample. A backup autofocusing routine at incident light allows automated refocusing between individual samples and can reestablish the focal plane after fatal focusing errors at epifluorescence illumination. The system was calibrated to produce relative abundances of FISH-stained cells in North Sea samples that were comparable to results obtained by manual evaluation. Up to 28 preparations could be analyzed within 4 h without operator interference. The device was subsequently applied for the counting of different microbial populations in incubation series of North Sea waters. Automated digital microscopy greatly facilitates the processing of numerous FISH-stained samples and might thus open new perspectives for bacterioplankton population ecology.     

Glucose gradient differences in subcutaneous tissue of healthy volunteers assessed with ultraslow microdialysis and a nanolitre glucose sensor

The abdominal subcutaneous interstitium is easily accessible for monitoring glucose for Diabetes Mellitus research and management. The available glucose sensing devices demand frequent blood sampling by finger pricking for calibration. Moreover, there is controversy about the exact relationship between the levels of glucose in the subcutis and blood. In the present study ultra-slow microdialysis was applied for subcutaneous fluid sampling, allowing continuous measurement of glucose in an equilibrated fluid using a nanolitre size sensor. The present method avoids in vivo calibration. During an oral glucose tolerance test glucose levels were measured simultaneously in blood, in adipose tissue and loose connective tissue layers of the abdominal subcutis in seven healthy subjects. Fasting glucose levels (mM) were 2.52 +/- 0.77 in adipose tissue and 4.67 +/- 0.17 in blood, this difference increasing to 6.40 +/- 1.57 and 11.59 +/- 1.52 at maximal glucose concentration. Moreover, the kinetics of glucose in blood and adipose tissue were different. In contrast, connective tissue glucose levels differed insignificantly (4.71 +/- 0.21 fasting and 11.70 +/- 1.96 at maximum) from those in blood and correlated well (r2 = 0.962). Ultra-slow microdialysis combined with a nanolitre glucose sensor could be of benefit to patients in intensive diabetes therapy. Frequent blood sampling for in vivo calibration can be avoided by monitoring glucose in the abdominal subcutaneous loose connective tissue, rather than in the adipose tissue.