Aging alters the functional expression of enzymatic and non-enzymatic anti-oxidant defense systems in testicular rat Leydig cells

In aged rats, trophic hormone-stimulated testosterone secretion by isolated Leydig cells is greatly reduced. The current studies were initiated to establish a functional link between excess oxidative stress and the age-related decline in steroidogenesis. Highly purified Leydig cell preparations obtained from 5-month (young mature) and 24-month (old) Sprague-Dawley rats were employed to measure and compare levels of lipid peroxidation, non-enzymatic (alpha-tocopherol, ascorbic acid, and reduced/oxidized glutathione) and enzymatic (Cu, Zn-superoxide dismutase, Cu, Zn-SOD; Mn-superoxide dismutase, Mn-SOD; glutathione peroxidase-1, GPX-1, and catalase, CAT) anti-oxidants. The extent of lipid peroxidation (oxidative damage) in isolated membrane fractions was quantified by measuring the content of thiobarbituric acid-reactive substances (TBARS) under basal conditions, or in the presence of non-enzymatic or enzymatic pro-oxidants. Membrane preparations isolated from Leydig cells from old rats exhibited two- to three-fold enhancement of basal TBARS formation. However, aging had no significant effect on TBARS formation in response to either non-enzymatic or enzymatic pro-oxidants. Among the non-enzymatic anti-oxidants, the levels of reduced glutathione were drastically reduced during aging, while levels of alpha-tocopherol and ascorbic acid remained unchanged. Both steady-state mRNA levels and catalytic activities of Cu, Zn-SOD, Mn-SOD, and GPX-1 were also significantly lower in Leydig cells from 24-month-old rats as compared with 5-month-old control rats. In contrast, neither mRNA levels nor enzyme activity of catalase was sensitive to aging. From these data we conclude that aging is accompanied by reduced expression of key enzymatic and non-enzymatic anti-oxidants in Leydig cells leading to excessive oxidative stress and enhanced oxidative damage (lipid peroxidation). It is postulated that such excessive oxidative insult may contribute to the observed age-related decline in testosterone secretion by testicular Leydig cells.     

Association of the CTLA4 Gene with Graves' Disease in the Chinese Han Population

To determine whether genetic heterogeneity exists in patients with Graves'' disease (GD), the cytotoxic T-lymphocyte associated 4 (CTLA-4) gene, which is implicated a susceptibility gene for GD by considerable genetic and immunological evidence, was used for association analysis in a Chinese Han cohort recruited from various geographic regions. Our association study for the SNPs in the CTLA4 gene in 2640 GD patients and 2204 control subjects confirmed that CTLA4 is the susceptibility gene for GD in the Chinese Han population. Moreover, the logistic regression analysis in the combined Chinese Han cohort revealed that SNP rs231779 (allele frequencies p = 2.81×10⁻⁹, OR = 1.35, and genotype distributions p = 2.75×10⁻⁹, OR = 1.42) is likely the susceptibility variant for GD. Interestingly, the logistic regression analysis revealed that SNP rs35219727 may be the susceptibility variant to GD in the Shandong population; however, SNP, rs231779 in the CTLA4 gene probably independently confers GD susceptibility in the Xuzhou and southern China populations. These data suggest that the susceptibility variants of the CTLA4 gene varied between the different geographic populations with GD.     

Studies on the Free Amino Acid Content in Anthers of Malesterile and Fertile Plants of Taigu Wheat,with Special Reference to Free Proline Content

Biochemical analyses were made on anthers and pistils at various developmental stages of both male-sterne and fertile plants of Taigu wheat. Analyses ineluded total free amino aeids and free proline. The following results were obtained: 1. There was no significant difference between the content of free proline in anthers of male-sterile and fertile plants at reduction division of mierospore mother cells. 2. In anthers with early uninucleate miorospores, the content of free proline of fertile plants was remarkably higher than that of male-sterile plants. It is interesting to note that at this stage the content of free proline in fertile plants rose to 1.65% of the dry weight of the anther, constituting 50% of the total free amino acids, and amounted to 7-fold of that in male-sterile plants. This result is in line with the results obtained with most cytoplasmic malesterile plants reported by other workers, although malesterility in Taigu wheat is controlled by the nueleus. 3. In pistils, at the stages eorresponding to the early uninneleate and the binueleate stages of the pollen, the free proline content of fertile plants was twice as much as that of the male-sterile plants. This differenee disappeared gradually after fertilization. 4. Tile content of total free amino aoids did not fluetuate as much as the free proline content. There was no differenee in anthers of both types of plants during reduction division of mierospore mother cells. In anthers with early uninueleate pollen grains, total free amino acid content of fertile plants exceeded that of male-sterile plant, the difference levelled off at latter stages. In pistils, before fertilization, the content of total free amino acids of the fertile phmts was slightly higher than that of the male-sterile plants. After fertilization t}fis difference was no nmre noticeable.     

The enzymes of a marine bacterial isolate from the brown alga <Emphasis Type="Italic">Sargassum polycystum</Emphasis> agardh, 1821, that catalyzes the transformation of polyanionic oligo-and polysaccharides

A search for enzymes involved in the degradation of polyanionic polysaccharides (fucoidans and alginic acid) was conducted among bacterial epiphytes of the brown alga Sargassum polycystum that grows in the territorial waters of the Socialist Republic of Vietnam. Two resistant bacterial strains, F10 and F14, have been isolated from the algal microflora that degrade the thallus of the alga under laboratory conditions. These bacterial strains differed in the morphological, physiological, and biochemical characteristics and in the composition of enzymes. The strains were studied for the ability to synthesize intracellular oligo-and polysaccharide hydrolases and alginate lyases. The optimal conditions for the growth of bacterial strain F14 and the biosynthesis of fucoidanase and polymannuronate-specific alginate lyase were determined. The partially purified alginate lyase was stable at a temperature up to 40°C and had an optimal pH 6.0 and an optimal temperature 35°C.     

Stable Li Metal Anode Enabled by Space Confinement and Uniform Curvature through Lithiophilic Nanotube Arrays

The application of lithium (Li) metal anodes in rechargeable batteries is primarily restricted by Li dendrite growth on the metal's surface, which leads to shortened cycle life and safety concerns. Herein, well‐spaced nanotubes with ultrauniform surface curvature are introduced as a Li metal anode structure. The ultrauniform nanotubular surface generates uniform local electric fields that evenly attract Li‐ions to the surface, thereby inducing even current density distribution. Moreover, the well‐defined nanotube spacing offers Li diffusion pathways to the electroactive areas as well as the confined spaces to host deposited Li. These structural attributes create a unique electrodeposition manner; i.e., Li metal homogenously deposits on the nanotubular wall, causing each Li nanotube to grow in circumference without obvious sign of dendritic formation. Thus, the full‐cell battery with the spaced Li nanotubes exhibits a high specific capacity of 132 mA h g^?1 at 1 C and an excellent coulombic efficiency of ≈99.85% over 400 cycles.     

BcMF9, a novel polygalacturonase gene, is required for both Brassica campestris intine and exine formation

Background and Aims

The polygalacturonase (PG) gene family has been found to be enriched in pollen of several species; however, little is currently known about the function of the PG gene in pollen development. To investigate the exact role that the PG gene has played in pollen development and about this family in general, one putative PG gene, Brassica campestris Male Fertility 9 (BcMF9), was isolated from Chinese cabbage (Brassica campestris ssp. chinensis, syn. B. rapa ssp. chinensis) and characterized.

Methods

RT-PCR, northern blotting and in situ hybridization were used to analyse the expression pattern of BcMF9, and antisense RNA technology was applied to study the function of this gene.

Key Results

BcMF9 is expressed in particular in the tapetum and microspore during the late stages of pollen development. Antisense RNA transgenic plants that displayed decreased expression of BcMF9 showed pollen morphological defects that resulted in reduced pollen germination efficiency. Transmission electron microscopy revealed that the homogeneous pectic exintine layer of pollen facing the exterior was over-developed and predominantly occupied the intine, reversing the normal proportional distribution of the internal endintine layer and the external exintine in transgenic pollen. Inhibition of BcMF9 also resulted in break-up of the previously formed tectum and baculae from the beginning of the binucleate stage, as a result of premature degradation of tapetum.

Conclusions

Several lines of evidence, including patterns of BcMF9 expression and phenotypic defects, suggest a sporophytic role in exine patterning, and a gametophytic mode of action of BcMF9 in intine formation. BcMF9 might act as a co-ordinator in the late stages of tapetum degeneration, and subsequently in the regulation of wall material secretion and, in turn, exine formation. BcMF9 might also play a role in intine formation, possibly via regulation of the dynamic metabolism of pectin.Key words: Brassica campestris, Chinese cabbage, exine, intine, PG, pollen wall, polygalacturonase, BcMF9     

Characteristic chemical probing patterns of loop motifs improve prediction accuracy of RNA secondary structures

RNA structures play a fundamental role in nearly every aspect of cellular physiology and pathology. Gaining insights into the functions of RNA molecules requires accurate predictions of RNA secondary structures. However, the existing thermodynamic folding models remain less accurate than desired, even when chemical probing data, such as selective 2′-hydroxyl acylation analyzed by primer extension (SHAPE) reactivities, are used as restraints. Unlike most SHAPE-directed algorithms that only consider SHAPE restraints for base pairing, we extract two-dimensional structural features encoded in SHAPE data and establish robust relationships between characteristic SHAPE patterns and loop motifs of various types (hairpin, internal, and bulge) and lengths (2–11 nucleotides). Such characteristic SHAPE patterns are closely related to the sugar pucker conformations of loop residues. Based on these patterns, we propose a computational method, SHAPELoop, which refines the predicted results of the existing methods, thereby further improving their prediction accuracy. In addition, SHAPELoop can provide information about local or global structural rearrangements (including pseudoknots) and help researchers to easily test their hypothesized secondary structures.