Evolution under relaxed sexual conflict in the bulb mite Rhizoglyphus robini

The experimental evolution under different levels of sexual conflict have been used to demonstrate antagonistic coevolution in muscids, but among other taxa a similar approach has not been employed. Here, we describe the results of 37 generations of evolution under either experimentally enforced monogamy or polygamy in the bulb mite Rhizoglyphus robini. Three replicates were maintained for each treatment. Monogamy makes male and female interests congruent; thus selection is expected to decrease harmfulness of males to their partners. Our results were consistent with this prediction in that females from monogamous lines achieved lower fecundity when housed with males from polygamous lines. Fecundity of polygamous females was not affected by mating system under which their partners evolved, which suggests that they were more resistant to male-induced harm. As predicted by the antagonistic coevolution hypothesis, the decrease in harmfulness of monogamous males was accompanied by a decline in reproductive competitiveness. In contrast, female fecundity and embryonic viability, which were not expected to be correlated with male harmfulness, did not differ between monogamous and polygamous lines. None of the fitness components assayed differed between individuals obtained from crosses between parents from the same line and those obtained from crosses between parents from different lines within the same mating system. This indicates that inbreeding depression did not confound our results. However, interpretation of our results is complicated by the fact that both males and females from monogamous lines evolved smaller body size compared to individuals from polygamous lines. Although a decrease in reproductive performance of males from monogamous lines was still significant when body size was taken into account, we were not able to separate the effects of male body size and mating system in their influence on fecundity of their female partners.     

Effects of red wine polyphenolic compounds on paraoxonase-1 and lectin-like oxidized low-density lipoprotein receptor-1 in hyperhomocysteinemic mice

Hyperhomocysteinemia, or abnormally high plasma homocysteine (Hcy) concentration, has often been associated with vascular thrombosis and the development of premature atherosclerosis. Many studies have shown that moderate wine consumption has potential beneficial effects related to the prevention of atherosclerosis, in part attributed to the biological properties of polyphenolic components, mainly flavonoids. The aim of the present study is to determine the effects of a red wine polyphenolic extract (PE) administration on hyperhomocysteinemia due to cystathionine beta-synthase (CBS) deficiency and on the associated biochemical markers of hepatic and endothelial dysfunctions in mice. Red wine PE was added for 4 weeks to the drinking water of heterozygous CBS-deficient mice fed a high-methionine diet, a murine model of hyperhomocysteinemia. Red wine PE supplementation at low dose significantly reduced plasma Hcy levels and restored the hepatic and plasma-decreased paraoxonase-1 activity induced by chronic hyperhomocysteinemia. Moreover, aortic expression of proinflammatory cytokines and adhesion molecules and levels of soluble lectin-like oxidized low-density lipoprotein receptor-1 were reduced in hyperhomocysteinemic mice fed the red wine PE supplementation. These findings suggest that red wine PE administration in low quantities has beneficial effects on biochemical markers of endothelial dysfunction due to hyperhomocysteinemia.     

Ascorbate and glutathione metabolism during development and desiccation of beech (<Emphasis Type="Italic">Fagus sylvatica</Emphasis> L.) seeds

The ascorbate-glutathione system was studied during development and maturation of beech (Fagus sylvatica L.) seeds, the classification of which in the orthodox category is controversial. This study revealed an increase in glutathione content after acquisition of desiccation tolerance, which was more intensive in embryonic axes than in cotyledons. During seed maturation, the redox status of glutathione markedly changed toward the more reducing state, especially in cotyledons. Ascorbic acid content decreased during maturation, mostly in cotyledons. Activities of the enzymes of the ascorbate-glutathione cycle—ascorbate peroxidase (APX, EC 1.11.1.11), monodehydroascorbate reductase (MR, EC 1.6.5.4), dehydroascorbate reductase (DHAR, EC 1.8.5.1) and glutathione reductase (GR, EC 1.6.4.2)—were markedly higher in embryonic axes than in cotyledons throughout the study period. In the course of seed maturation, the activities of these enzymes decreased. Importance of the ascorbate-glutathione cycle in desiccation tolerance of beech seeds was discussed in relation to results for typical orthodox and recalcitrant seeds of other broadleaved species.     

Bidirectional regulation of renal cortical Na+,K+-ATPase by protein kinase C

We examined the role of protein kinase C (PKC) in the regulation of Na+,K+- ATPase activity in the renal cortex. Male Wistar rats were anaesthetized and the investigated reagents were infused into the abdominal aorta proximally to the renal arteries. A PKC-activating phorbol ester, phorbol 12,13-dibutyrate (PDBu), had a dose-dependent effect on cortical Na+,K+-ATPase activity. Low dose of PDBu (10(-11) mol/kg per min) increased cortical Na+,K+-ATPase activity by 34.2%, whereas high doses (10(-9) and 10(-8) mol/kg per min) reduced this activity by 22.7% and 35.0%, respectively. PDBu administration caused changes in Na+,K+-ATPase Vmax without affecting K(0.5) for Na+, K+ and ATP as well as Ki for ouabain. The effects of PDBu were abolished by PKC inhibitors, staurosporine, GF109203X, and G? 6976. The inhibitory effect of PDBu was reversed by pretreatment with inhibitors of cytochrome P450-dependent arachidonate metabolism, ethoxyresorufin and 17-octadecynoic acid, inhibitors of phosphatidylinositol 3-kinase (PI3K), wortmannin and LY294002, and by actin depolymerizing agents, cytochalasin D and latrunculin B. These results suggest that PKC may either stimulate or inhibit renal cortical Na+,K+-ATPase. The inhibitory effect is mediated by cytochrome P450-dependent arachidonate metabolites and PI3K, and is caused by redistribution of the sodium pump from the plasma membrane to the inactive intracellular pool.     

Chromatographic and Biological Screening of Chosen Species of Schisandraceae Family: Schisandra chinensis,S. rubriflora,S. sphenanthera,S. henryi and Kadsura japonica

HPLC and TLC profiling was carried out for leaf and fruit extracts of five Schisandraceae species: Schisandra chinensis, S. rubriflora, S. spehenanthera, S. henryi and Kadsura japonica. HPLC measurements confirmed presence of lignans and phenolic compounds in fruits and leaves of all tested species. The most abundant in lignans was S. chinensis fruit extract in which 15 compounds were detected (e. g.: schisandrol A, schisanhenol, γ-schisandrin, gomisin N). The effect-directed detection, i. e., TLC-direct bioautography against Bacillus subtilis, showed exceptionally high activity for S. chinensis and S. rubriflora fruit extracts. On the other hand, TLC-DB enzyme tests (α-glucosidase, lipase, tyrosinase and acetylcholinesterase (AChE) inhibition assays) showed that all fruit and leaf extracts have ability to inhibit the above-mentioned enzymes (except for the K. japonica fruit). The leaf extracts showed much stronger antioxidant activity than the fruit ones, which were assessed and compared using both TLC-direct bioautography and spectrophotometric measurements based on ABTS, DPPH and FRAP tests.     

Functional role and ribosomal position of the unique N-terminal region of DHX29, a factor required for initiation on structured mammalian mRNAs

Translation initiation on structured mammalian mRNAs requires DHX29, a DExH protein that comprises a unique 534-aa-long N-terminal region (NTR) and a common catalytic DExH core. DHX29 binds to 40S subunits and possesses 40S-stimulated NTPase activity essential for its function. In the cryo-EM structure of DHX29-bound 43S preinitiation complexes, the main DHX29 density resides around the tip of helix 16 of 18S rRNA, from which it extends through a linker to the subunit interface forming an intersubunit domain next to the eIF1A binding site. Although a DExH core model can be fitted to the main density, the correlation between the remaining density and the NTR is unknown. Here, we present a model of 40S-bound DHX29, supported by directed hydroxyl radical cleavage data, showing that the intersubunit domain comprises a dsRNA-binding domain (dsRBD, aa 377–448) whereas linker corresponds to the long α-helix (aa 460–512) that follows the dsRBD. We also demonstrate that the N-terminal α-helix and the following UBA-like domain form a four-helix bundle (aa 90–166) that constitutes a previously unassigned section of the main density and resides between DHX29’s C-terminal α-helix and the linker. In vitro reconstitution experiments revealed the critical and specific roles of these NTR elements for DHX29’s function.     

Production and scavenging of reactive oxygen species in Fagus sylvatica seeds during storage at varied temperature and humidity

The accumulation of reactive oxygen species (ROS) in seed tissues plays an important role in the loss of seed viability during storage. In the present study, we examined whether the loss of germination capacity and viability of beech (Fagus sylvatica L.) seeds during storage under different temperatures (4, 20 and 30 degrees C) and relative humidity levels (45% and 75% RH) is associated with: (1) an increase in the level of ROS, such as superoxide radical (O2*-), oxygen peroxide (H2O2); and, (2) changes in low molecular antioxidants (ascorbate and glutathione) and enzymatic scavengers such as ascorbate peroxidase dehydroascorbate reductase, glutathione reductase, catalase, superoxide dismutase and guaiacol peroxidase. Beech seeds progressively lost their ability to germinate during 9 weeks of storage under the above conditions. The deleterious effects of temperature treatments increased with growing seed moisture content at higher humidity. The loss of seed viability was correlated with the generation of ROS during storage, which was more intensive at higher temperatures and humidity levels. The ascorbate content significantly increased in seeds stored in all temperature and humidity variants, when the seeds lost the ability to germinate to a large degree. At the same time, glutathione content dramatically decreased, but it was possible to observe a defensive reaction in seeds stored at 20 degrees C. Activities of all scavenging enzymes, measured after slow imbibition of seeds, significantly increased in comparison to the non-treated control (8-9% MC, -10 degrees C). This increase was higher in embryo axes than in cotyledons. Our results suggest that the loss of viability of beech seeds during storage at different temperatures, above zero, and at different humidity levels is closely related to ROS production, and that the antioxidative system is not sufficient to protect them.