MITOCHONDRIAL-DNA ANALYSES AND THE ORIGIN AND RELATIVE AGE OF PARTHENOGENETIC LIZARDS (GENUS CNEMIDOPHORUS). III. C. VELOX AND C. EXSANGUIS

Mitochondrial DNAs (mtDNAs) of two unisexual, parthenogenetically reproducing species of whiptail lizards (Cnemidophorus velox and C. exsanguis) and their bisexual relatives were compared by restriction-enzyme analysis to assess levels of mtDNA variation and to establish the maternal ancestry of the unisexuals. No cleavage-site differences were found to be diagnostic between C. velox and C. exsanguis mtDNAs, suggesting an ancestry rooted in the same maternal lineage. The mtDNA of the unisexuals is relatively homogeneous, indicating that these lineages are of recent origin. Phylogenetic analysis revealed that the maternal ancestor of both C. velox and C. exsanguis was most probably C. burti stictogrammus, C. costatus barrancorum, or an unidentified taxon closely related to them. In addition, the mtDNA analyses demonstrate conclusively that the triploid species C. velox could not have been formed by the fertilization of an unreduced (diploid) C. inornatus egg, further strengthening the hypothesis that parthenogenesis in Cnemidophorus results from hybridization.     

Effect of Growth Rate and Starvation-Survival on the Viability and Stability of a Psychrophilic Marine Bacterium

Cell populations of the marine bacterium ANT-300, from either batch or continuous culture with dilution rates ranging from D = 0.015 h⁻¹ to D = 0.200 h⁻¹, were monitored for viability, direct counts, and optical density for 98 days under starvation conditions. Three stages of starvation survival were observed for each of the cell populations. Although direct counts remained at 2 × 10⁷ to 3 × 10⁷ cells ml⁻¹ throughout the starvation period, large fluctuations occurred in cell viability during stage 1 (0 to 14 days) of starvation survival. Stage 2 (14 to 70 days) involved an overall decrease in viability for each of the cell populations; the rate of viability loss was dependent upon the growth rate. Cell viability stabilized at approximately 0.3% of the direct count in stage 3 (70 to 98 days). Long-term starvation corresponded to the prolongation of stage 3 starvation survival. Cell volumes for each of the cell populations decreased with the length of the starvation period. However, the cell volume of starved cells was also dependent more on growth rate than on the length of the time starved. We hypothesize that the cell population with the slowest growth rate is most closely representative of cells found in the oligotrophic marine environment.     

Identification of a gonadotropin-releasing hormone receptor orthologue in Caenorhabditis elegans

Background  

The Caenorhabditis elegans genome is known to code for at least 1149 G protein-coupled receptors (GPCRs), but the GPCR(s) critical to the regulation of reproduction in this nematode are not yet known. This study examined whether GPCRs orthologous to human gonadotropin-releasing hormone receptor (GnRHR) exist in C. elegans.     

Effect of temperature on tether extraction, surface protrusion, and cortical tension of human neutrophils

Neutrophil rolling on endothelial cells, the initial stage of its migrational journey to a site of inflammation, is facilitated by tether extraction and surface protrusion. Both phenomena have been studied extensively at room temperature, which is considerably lower than human body temperature. It is known that temperature greatly affects cellular mechanical properties such as viscosity. Therefore, we carried out tether extraction, surface protrusion, and cortical tension experiments at 37 degrees C with the micropipette aspiration technique. The experimental temperature was elevated using a custom-designed microscope chamber for the micropipette aspiration technique. To evaluate the constant temperature assumption in our experiments, the temperature distribution in the whole chamber was computed with finite element simulation. Our simulation results showed that temperature variation around the location where our experiments were performed was less than 0.2 degrees C. For tether extraction at 37 degrees C, the threshold force required to pull a tether (40 pN) was not statistically different from the value at room temperature (51 pN), whereas the effective viscosity (0.75 pN.s/microm) decreased significantly from the value at room temperature (1.5 pN.s/microm). Surface protrusion, which was modeled as a linear deformation, had a slightly smaller spring constant at 37 degrees C (40 pN/microm) than it did at room temperature (56 pN/microm). However, the cortical tension at 37 degrees C (5.7+/-2.2 pN/microm) was substantially smaller than that at room temperature (23+/-8 pN/microm). These data clearly suggest that neutrophils roll differently at body temperature than they do at room temperature by having distinct mechanical responses to shear stress of blood flow.     

Blood pressure and hypertension in an American colony (Puerto Rico) and on the USA mainland compared, 1886–1930

We compare blood pressure and hypertension between adult men on the USA mainland and in Puerto Rico born during 1886-1930 to test hypotheses about the link between cardiovascular health and large socioeconomic and political changes in society: (a) 8853 men surveyed in Puerto Rico in 1965 and (b) 1449 non-Hispanic White men surveyed on the mainland during 1971-1975. Systolic and diastolic blood pressure and hypertension were regressed separately on demographic and socioeconomic variables and cardiovascular risk factors. Mainland men not taking anti-hypertensive medication showed statistically significant improvements in systolic blood pressure and hypertension at the beginning of the century and men in Puerto Rico showed improvements in diastolic blood pressure but only during the last two quinquenniums. An average man born on the mainland during the last birth quinquennium (1926-1930) had 7.4-8.7 mmHg lower systolic blood pressure and was 61% less likely to have systolic hypertension than one born before 1901. On average Puerto Rican men born during 1921-1925 had approximately 1.7 mmHg lower diastolic blood pressure than men born before 1901. Analyses of secular trends in cardiovascular health complements analyses of secular trends in anthropometric indicators and together provide a fuller view of the changing health status of a population.     

Evolutionary history predicts high‐impact invasions by herbivorous insects

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Evaluation of organic insecticides for management of spotted‐wing drosophila (Drosophila suzukii) in berry crops

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The Bax subfamily of Bcl2-related proteins is essential for apoptotic signal transduction by c-Jun NH(2)-terminal kinase

Targeted gene disruption studies have established that the c-Jun NH(2)-terminal kinase (JNK) signaling pathway is required for stress-induced release of mitochondrial cytochrome c and apoptosis. Here we demonstrate that activated JNK is sufficient to induce rapid cytochrome c release and apoptosis. However, activated JNK fails to cause death in cells deficient of members of the Bax subfamily of proapoptotic Bcl2-related proteins. Furthermore, exposure to stress fails to activate Bax, cause cytochrome c release, and induce death in JNK-deficient cells. These data demonstrate that proapoptotic members of the Bax protein subfamily are essential for JNK-dependent apoptosis.