Arabidopsis Villins Promote Actin Turnover at Pollen Tube Tips and Facilitate the Construction of Actin Collars

Apical actin filaments are crucial for pollen tube tip growth. However, the specific dynamic changes and regulatory mechanisms associated with actin filaments in the apical region remain largely unknown. Here, we have investigated the quantitative dynamic parameters that underlie actin filament growth and disappearance in the apical regions of pollen tubes and identified villin as the major player that drives rapid turnover of actin filaments in this region. Downregulation of Arabidopsis thaliana VILLIN2 (VLN2) and VLN5 led to accumulation of actin filaments at the pollen tube apex. Careful analysis of single filament dynamics showed that the severing frequency significantly decreased, and the lifetime significantly increased in vln2 vln5 pollen tubes. These results indicate that villin-mediated severing is critical for turnover and departure of actin filaments originating in the apical region. Consequently, the construction of actin collars was affected in vln2 vln5 pollen tubes. In addition to the decrease in severing frequency, actin filaments also became wavy and buckled in the apical cytoplasm of vln2 vln5 pollen tubes. These results suggest that villin confers rigidity upon actin filaments. Furthermore, an observed decrease in skewness of actin filaments in the subapical region of vln2 vln5 pollen tubes suggests that villin-mediated bundling activity may also play a role in the construction of actin collars. Thus, our data suggest that villins promote actin turnover at pollen tube tips and facilitate the construction of actin collars.     

中药灵香草及其混淆品种的比较鉴别

本文比较了中药灵香草Lysimachia foenum-graecum Hance及其混淆品种垂花香草Lysimaehia nutantiflora Chen et C.M.Hu的植物形态、药材性状以及茎、叶组织显微特征。指出垂花香草无灵香草特有的芳香。也无药用记载。应仔细区别,不宜混用。     

Isolation of microbodies from plant tissues

Specialized microbodies have previously been isolated and characterized from fatty seedling tissues (glyoxysomes) and leaves (leaf peroxisomes). We have now examined 11 other plant tissues, including tubers, fruits, roots, shoots, and petals, and find that all contain particulate catalase, a distinctive common enzyme component of microbodies. On linear sucrose gradients the catalase activity peaks sharply at a higher equilibrium density (1.20 to 1.25 gram per cm³ in the various tissues) than the mitochondria (1.17 to 1.20). Only small amounts of protein are recovered in the fractions containing catalase, although a definite band is visible in preparations from some tissues, e.g., potato. As in the preparations from castor bean endosperm and spinach leaves for which comparable data are provided, the distribution of glycolate oxidase and uricase follows closely that of catalase on the gradients. The preparations from potato lack glyoxylate reductase and the transaminases, typical enzymes of leaf peroxisomes, and the distinctive enzymes of glyoxysomes are missing. Nonspecialized microbodies with limited enzyme composition can thus be isolated from a variety of plant tissues.     

Association study between of Tie2/Angiopoietin-2 and VEGF/KDR pathway gene polymorphisms and vascular malformations

Vascular malformations (VMs) are common congenital and neonatal dysmorphogenesis. VMs mostly occur sporadically with a few exceptions of inheritability. Tie2/angiopoietins-2 (Ang-2) and VEGF/KDR pathways are known to be involved in normal and pathogenic angiogenesis. Our study was aimed to test the contribution of these pathway gene variants to VMs. A total of 8 variants were found among 103 VM patients and 142 healthy controls. These variants comprised rs638203, rs639225, rs80338908 and rs80338909 in Tie2 gene, rs1870377 and rs2305949 in KDR gene, rs79337921 and rs34590960 in ANTXR1 gene. Our results indicated that rs638203 (p = 0.029) and rs639225 (p = 0.018) in Tie2 gene were associated with VM. A further bioinformatics analysis suggested the rs638203-G and rs639225-G might cause an abnormal splicing of Tie2 gene into to a defective protein. Our results identified two novel Tie2 gene polymorphisms with genetic susceptibility to VMs, although future functional validation of the two polymorphisms is warranted in the future.     

Ursolic acid prevents doxorubicin‐induced cardiac toxicity in mice through eNOS activation and inhibition of eNOS uncoupling

In addition to the known antitumour effects of ursolic acid (UA), increasing evidence indicates that this molecule plays a role in cardiac protection. In this study, the effects of ursolic acid on the heart in mice treated with doxorubicin (DOX) were assessed. The results showed that ursolic acid improved left ventrical fractional shortening (LVFS) and left ventrical ejection fraction (LVEF) of the heart, increased nitrogen oxide (NO) levels, inhibited reactive oxygen species (ROS) production and decreased cardiac apoptosis in mice treated with doxorubicin. Mechanistically, ursolic acid increased AKT and endothelial nitric‐oxide synthase (eNOS) phosphorylation levels, and enhanced eNOS expression, while inhibiting doxorubicin induced eNOS uncoupling through NADPH oxidase 4 (NOX4) down‐regulation. These effects of ursolic acid resulted in heart protection from doxorubicin‐induced injury. Therefore, ursolic acid may be considered a potential therapeutic agent for doxorubicin‐associated cardiac toxicity in clinical practice.     

Differential effects of paraoxonase 1 (PON1) polymorphisms on cancer risk: evidence from 25 published studies

Paraoxonase is an HDL-associated enzyme that plays a preventive role against oxidative stress, which is thought to contribute to cancer development. PON1 activity varies widely among individuals, which is in part related to two common nonsynonymous polymorphisms in the PON1 gene (Q192R and L55M). The polymorphisms in PON1 have been implicated in cancer risk. However, results from the studies to date have been conflicting. To clarify the association, a meta-analysis was performed for 7,073 cases and 9,520 controls from 25 published case–control studies. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of the association. Significant associations between PON1-L55M but not Q192R polymorphism and total cancer were observed from all the comparisons. In stratified analyses, PON1-55M allele was a risk factor for breast cancer. Similarly, increased risk was observed for prostate cancer (OR = 1.18, 95% CI: 1.01–1.36, P _{heterogeneity} = 0.260) and Caucasian population (OR = 1.18, 95% CI: 1.02–1.38, P _{heterogeneity} = 0.1) of the LM genotype, compared with the LL genotype. For PON1-Q192R polymorphism, PON1-192R allele was a decreased risk factor for cancer in the Asian group (RR vs QQ: OR = 0.61, 95% CI: 0.38–0.98, P _{heterogeneity} = 0.268; QR vs QQ: OR = 0.71, 95% CI: 0.52–0.96, P _{heterogeneity} = 0.130; RR + QR vs QQ: OR = 0.71, 95% CI: 0.53–0.95, P _{heterogeneity} = 0.135). Although some modest bias could not be eliminated, this meta-analysis suggests that the PON1-55M allele is a risk factor for the development of cancer, in particular for breast cancer. Future studies with larger sample sizes are warranted to further evaluate these associations.     

Improving rice yield and quality by QTL pyramiding

To facilitate marker-assisted transfer of desirable genes for improvement of yield traits, we used a set of backcross recombinant inbred lines (BRIL) derived from two elite parental lines, ‘Zhenshan97’ and ‘93-11’, to resolve a quantitative trait loci (QTL) cluster for heading date and yield-related traits in rice. Four main-effect QTL (qHD6.1, qHD6.2, qHD7, and qHD8) and four epistatic QTL affecting heading date in the BRIL were detected in two experimental trials. The major QTL (qHD8) was confirmed in three heterogeneous inbred families (HIF) that segregated for this target region, and narrowed down to a 20-kb segment in a large HIF-derived population. qHD8 was found to interact with qHD7 and had a pleiotropic effect responsible for heading date and yield components. To test usability of the identified QTL in rice improvement, we further developed near-isogenic lines (NIL) containing one or more target genes by marker-assisted transfer of ‘93-11’ alleles at qHD8, qHD7, and qHD6.1, and the GS3 gene for grain size into ‘Zhenshan97’. The pyramid line NIL(qHD8 + GS3) had higher yield potential, longer grains, and a more suitable heading date than ‘Zhenshan97’. Comparison of the NIL showed existence of epistasis between alleles at different loci and background effect on qHD8, which are very important for pyramiding of desirable alleles at the target QTL. These results will be particularly useful not only to understand the genetic basis of yield-related traits but also to improve the efficiency of marker-assisted selection for favorable loci in rice breeding programs.     

Effects of caffeine on in vivo and in vitro oocyte maturation in mice

The objective was to investigate, using a mouse model, the effects of caffeine on the number of ovulated oocytes, the rate of oocyte maturation, the susceptibility of oocytes to activating stimuli, spindle morphology, and distribution of cortical granules (CGs). Mice were given caffeine (150 mg/kg body weight ip) at various times relative to hCG (-2, 0, and +2h); in an in vitro study, 1, 5 or 10 mM caffeine was added to the maturation culture. Caffeine had no effect on the quality of oocytes in vivo maturation, but caffeine was detrimental to the quality of oocytes matured in vitro. Further studies are needed to determine caffeine concentration in follicles relative to that in culture medium.