Plant biomechanical strategies in response to frequent disturbance: uprooting of Phyllostachys nidularia (Poaceae) growing on landslide-prone slopes in Sichuan, China

Bamboo is considered useful for controlling landslides, but we observed numerous shallow-slope failures in forests of big node bamboo (Phyllostachys nidularia) in Sichuan, China. Therefore, we inventoried landslide occurrence and vegetation type along one valley. To quantify bamboo root anchorage, we performed uprooting tests and measured plant morphological characteristics. Landslide occurrence was greatest at sites with bamboo and young trees. Culm failure was common because of the high length to diameter ratio (242 ± 6). Uprooting tests showed that the maximal force to cause failure was small (1615 ± 195 N). Uprooting force was strongly and positively regressed with a combination of the predictors lateral root number and volume (R(2) = 0.92), and root systems were highly superficial (depth = 0.15 ± 0.12 m), contributing little to slope stability. In P. nidularia, which grows on landslide-prone slopes, surprisingly few resources have been allocated to anchorage. We suggest that this strategy puts this pioneer at an advantage on steep slopes, where it contributes little to slope stability and colonizes frequently formed gaps through vegetative regeneration. Fewer disturbances would result in subsequent secondary succession and dying back of this shade intolerant species.     

A new perspective on the function of Tissue Non-Specific Alkaline Phosphatase: from bone mineralization to intra-cellular lipid accumulation

Molecular and Cellular Biochemistry - Tissue-nonspecific alkaline phosphatase (TNAP) is one of four isozymes, which include germ cell, placental and intestinal alkaline phosphatases. The TNAP...     

Influence of manufacturing processes on cell surface properties of probiotic strain <Emphasis Type="Italic">Lactobacillus rhamnosus</Emphasis> Lcr35<Superscript>®</Superscript>

The influence of the industrial process on the properties of probiotics, administered as complex manufactured products, has been poorly investigated. In the present study, we comparatively assessed the cell wall characteristics of the probiotic strain Lactobacillus rhamnosus Lcr35® together with three of its commercial formulations with intestinal applications. Putative secreted and transmembrane-protein-encoding genes were initially searched in silico in the genome of L. rhamnosus Lcr35®. A total of 369 candidate genes were identified which expressions were followed using a custom Lactobacillus DNA chip. Among them, 60 or 67 genes had their expression either upregulated or downregulated in the Lcr Restituo® packet or capsule formulations, compared to the native Lcr35® strain. Moreover, our data showed that the probiotic formulations (Lcr Lenio®, Lcr restituo® capsule and packet) showed a better capacity to adhere to intestinal epithelial Caco-2 cells than the native Lcr35® strain. Microbial (MATS) tests showed that the probiotic was an electron donor and that they were more hydrophilic than the native strain. The enhanced adhesion capacity of the active pharmaceutical ingredients (APIs) to epithelial Caco-2 cells and their antipathogen effect could be due to this greater surface hydrophilic character. These findings suggest that the manufacturing process influences the protein composition and the chemical properties of the cell wall. It is therefore likely that the antipathogen effect of the formulation is modulated by the industrial process. Screening of the manufactured products’ properties would therefore represent an essential step in evaluating the effects of probiotic strains.     

Sex allocation in haplodiploids is mediated by egg size: evidence in the spider mite Tetranychus urticae Koch

Haplodiploid species display extraordinary sex ratios. However, a differential investment in male and female offspring might also be achieved by a differential provisioning of eggs, as observed in birds and lizards. We investigated this hypothesis in the haplodiploid spider mite Tetranychus urticae, which displays highly female-biased sex ratios. We show that egg size significantly determines not only larval size, juvenile survival and adult size, but also fertilization probability, as in marine invertebrates with external fertilization, so that female (fertilized) eggs are significantly larger than male (unfertilized) eggs. Moreover, females with on average larger eggs before fertilization produce a more female-biased sex ratio afterwards. Egg size thus mediates sex-specific egg provisioning, sex and offspring sex ratio. Finally, sex-specific egg provisioning has another major consequence: male eggs produced by mated mothers are smaller than male eggs produced by virgins, and this size difference persists in adults. Virgin females might thus have a (male) fitness advantage over mated females.     

A specific protein disorder catalyzer of HIV-1 Nef

The HIV-1 auxiliary protein Nef is required for the onset and progression of AIDS in HIV-1-infected persons. Here, we have deciphered the mode of action of a second-generation inhibitor of Nef, DLC27-14, presenting a competitive IC(50) of ～16 μM measured by MALDI-TOF experiments. Thermal protein denaturation experiments revealed a negative effect on stability of Nef in the presence of a saturating concentration of the inhibitor. The destabilizing action of DLC27-14 was confirmed by a HIV protease-based experiment, in which the protease sensitivity of DLC27-14-bound Nef was three times as high as that of apo Nef. The only compatible docking modes of action for DLC27-14 suggest that DLC27-14 promotes an opening of two α-helices that would destabilize the Nef core domain. DLC27-14 thus acts as a specific protein disorder catalyzer that destabilizes the folded conformation of the protein. Our results open novel avenues toward the development of next-generation Nef inhibitors.