Cytisine attenuates bone loss of ovariectomy mouse by preventing RANKL‐induced osteoclastogenesis

Postmenopausal Osteoporosis (PMOP) is oestrogen withdrawal characterized of much production and activation by osteoclast in the elderly female. Cytisine is a quinolizidine alkaloid that comes from seeds or other plants of the Leguminosae (Fabaceae) family. Cytisine has been shown several potential pharmacological functions. However, its effects on PMOP remain unknown. This study designed to explore whether Cytisine is able to suppress RANKL‐induced osteoclastogenesis and prevent the bone loss induced by oestrogen deficiency in ovariectomized (OVX) mice. In this study, we investigated the effect of Cytisine on RAW 264.7 cells and bone marrow monocytes (BMMs) derived osteoclast culture system in vitro and observed the effect of Cytisine on ovariectomized (OVX) mice model to imitate postmenopausal osteoporosis in vivo. We found that Cytisine inhibited F‐actin ring formation and tartrate‐resistant acid phosphatase (TRAP) staining in dose‐dependent ways, as well as bone resorption by pit formation assays. For molecular mechanism, Cytisine suppressed RANK‐related trigger RANKL by phosphorylation JNK/ERK/p38‐MAPK, IκBα/p65‐NF‐κB, and PI3K/AKT axis and significantly inhibited these signalling pathways. However, the suppression of PI3K‐AKT‐NFATc1 axis was rescued by AKT activator SC79. Meanwhile, Cytisine inhibited RANKL‐induced RANK‐TRAF6 association and RANKL‐related gene and protein markers such as NFATc1, Cathepsin K, MMP‐9 and TRAP. Our study indicated that Cytisine could suppress bone loss in OVX mouse through inhibited osteoclastogenesis. All data provide the evidence that Cytisine may be a promising agent in the treatment of osteoclast‐related diseases such as osteoporosis.     

Intergeneric protoplast fusion between Kluyveromyces and Saccharomyces cerevisiae – to produce sorbitol from Jerusalem artichokes

The construction of inulin-assimilating and sorbitol-producing fusants was achieved by intergeneric protoplast fusion between Kluyveromyces sp. Y-85 and Saccharomyces cerevisiae E-15. The cells of parental strains were pretreated with 0.1% EDTA (w/v) and 2-mercaptoethanol (0.1%, v/v) and then exposed to 2.0% (w/v) Zymolase at 30 °C for 30–40 min. The optimized fusion condition demonstrated that with the presence of 30% (w/v) polyethylene glycol 6000 (PEG-6000) and 10 mM CaCl₂ for 30 min, the fusion frequency reached 2.64 fusants/10⁶ parental cells. The fusants were screened by different characters between two parental strains and further identified by DNA contents, inulinase activity and sorbitol productivity. One of the genetically stable fusants, Strain F27, reached a maximal sorbitol production of 4.87 g/100 ml under optimal fermentation condition.     

Critical biophysical properties in the Pseudomonas aeruginosa efflux gene regulator MexR are targeted by mutations conferring multidrug resistance

The self‐assembling MexA‐MexB‐OprM efflux pump system, encoded by the mexO operon, contributes to facile resistance of Pseudomonas aeruginosa by actively extruding multiple antimicrobials. MexR negatively regulates the mexO operon, comprising two adjacent MexR binding sites, and is as such highly targeted by mutations that confer multidrug resistance (MDR). To understand how MDR mutations impair MexR function, we studied MexR‐wt as well as a selected set of MDR single mutants distant from the proposed DNA‐binding helix. Although DNA affinity and MexA‐MexB‐OprM repression were both drastically impaired in the selected MexR‐MDR mutants, MexR‐wt bound its two binding sites in the mexO with high affinity as a dimer. In the MexR‐MDR mutants, secondary structure content and oligomerization properties were very similar to MexR‐wt despite their lack of DNA binding. Despite this, the MexR‐MDR mutants showed highly varying stabilities compared with MexR‐wt, suggesting disturbed critical interdomain contacts, because mutations in the DNA‐binding domains affected the stability of the dimer region and vice versa. Furthermore, significant ANS binding to MexR‐wt in both free and DNA‐bound states, together with increased ANS binding in all studied mutants, suggest that a hydrophobic cavity in the dimer region already shown to be involved in regulatory binding is enlarged by MDR mutations. Taken together, we propose that the biophysical MexR properties that are targeted by MDR mutations—stability, domain interactions, and internal hydrophobic surfaces—are also critical for the regulation of MexR DNA binding.     

Clonal growth and sexual reproduction: tradeoffs and environmental constraints

Clonal growth confers a number of benefits on plants, but involves some costs as well. We examined whether seed reproduction is reduced in clonal plants due to these costs. Further, we investigated whether this relationship differs for species with optima at stressful or low‐productivity sites, as a possible indication that clonality acts as insurance against reduced seed reproduction in such conditions. We evaluated 472 species for which seed production per unit area had been determined, and employed this information together with data on seed mass, height at maturity, clonal traits and optimum habitat conditions (using Ellenberg indicator values). There was a strong hyperbolic relationship between seed output and seed mass, with a scaling coefficient of ?1, indicative of a simple tradeoff relationship. We performed analyses both with and without taking phylogeny into account. Reproductive output (i.e. the product of seed output and seed size) of was lower in clonal than in non‐clonal plants (in both with and without phylogeny incorporated in the analyses); within non‐clonal species, it was high in annuals and monocarpic plants relative to nonclonal perennials. Reproductive output was lower in clonal plants with extensive lateral spread. This may be due to lower mortality of such plants, which should favor reduced reproductive output, but direct resource tradeoff may also be involved. Reproductive output in all clonal and non‐clonal plants increased with the nutrient status and light level of the species’ optimum, and decreased with moisture. Because the proportion of clonal plants in vegetation is known to decrease along the same gradients, we can infer that as sexual reproduction becomes increasingly difficult in terms of these characteristics, clonal plants may capitalize on their capacity to bypass it. However, the relationships with habitat parameters disappeared in the phylogenetically corrected analysis, indicating that habitat preferences and reproductive output evolved together.     

Saccharide-mediated antagonistic effects of bark beetle fungal associates on larvae

Bark beetles are among the most destructive of pine forest pests and they form close symbiotic relationships with ophiostomatoid fungi. Although some fungi are considered to be mutualistic symbionts of bark beetles with respect to the supply of nutrients, detrimental effects of fungal symbionts on larval growth have also been frequently reported. The mechanisms of such antagonistic effects are hypothesized to be a decrease in nutritional resources caused by competition for saccharides by the fungi. Here, we provide experimental evidence that three beetle-associated fungi modify the nutritional content of an artificial phloem diet, leading to a detrimental effect on the growth of Dendroctonus valens larvae. When larvae were fed a diet of pine phloem in agar medium colonized with any of these fungi, feeding activity was not affected but weight significantly decreased. Additional analysis showed that fungi depleted the fructose and glucose concentrations in the phloem media. Furthermore, these detrimental effects were neutralized by supplementing the media with fructose or glucose, suggesting that fungi may affect larval growth by modifying diet saccharide contents. These data indicate that fungus-induced nutritional changes in bark beetle diet can affect larval growth, and that the mechanism involves fungus-induced saccharide depletion from the larval diet.     

埃博拉病毒来源miRNA的研究综述

近年来,随着对microRNA（miRNA）的广泛研究,人们发现,不仅有细胞结构的生物具有产生miRNA的能力,无细胞结构的病毒同样具有产生miRNA从而影响自身复制及调控宿主基因表达和信号通路的能力。埃博拉病毒（Ebola virus,EBOV）已经多次导致一定规模的流行,病毒的高致死率和复杂的致病机制引起了人们的高度重视,多项研究指出EBOV具有产生miRNA的能力,且在其感染过程中发挥一定的作用。本文对埃博拉病毒来源miRNA的预测、证实及检测相关研究进行综述,以期为全面了解EBOV来源的miRNA提供参考。     

Analysis of DNA sequences of six chloroplast and nuclear genes suggests incongruence, introgression, and incomplete lineage sorting in the evolution of Lespedeza (Fabaceae)

The genus Lespedeza (Fabaceae) consists of 40 species disjunctively distributed in East Asia and eastern North America. Phylogenetic relationships of all Lespedeza species and closely related genera were reconstructed using maximum parsimony, maximum likelihood, and Bayesian analyses of sequence data from five chloroplast (rpl16, rpl32-trnL, rps16-trnQ, trnL-F, and trnK/matK) and one nuclear (ITS) DNA regions. All analyses yielded consistent relationships among major lineages. Our results suggested that Campylotropis, Kummerowia, and Lespedeza are monophyletic, respectively. Lespedeza is resolved as sister to Kummerowia and these two together are further sister to Campylotropis. Neither of the two subgenera, subgen. Lespedeza and subgen. Macrolespedeza, in Lespedeza based on morphological characters, is recovered as monophyletic. Within Lespedeza, the North American clade is retrieved as sister to the Asian clade. The nuclear and chloroplast markers showed incongruent phylogenetic signals at shallow-level phylogeny, which may point to either introgression or incomplete lineage sorting in Lespedeza. The divergence times within Lespedeza and among related genera were estimated using Bayesian approach with BEAST. It is assumed that following the divergence between Kummerowia and Lespedeza in Asia in the late Miocene, the ancestor of Lespedeza diverged into the North American and the Asian lineages. The North American ancestor quickly migrated to North America through the Bering land bridge in the late Miocene. The North American and Asian lineages started to diversify almost simultaneously in the late Miocene but resulted in biased numbers of species in two continents.     

Secretory leukocyte protease inhibitor plays an important role in the regulation of allergic asthma in mice

Secretory leukocyte protease inhibitor (SLPI) is an anti-inflammatory protein that is observed at high levels in asthma patients. Resiquimod, a TLR7/8 ligand, is protective against acute and chronic asthma, and it increases SLPI expression of macrophages in vitro. However, the protective role played by SLPI and the interactions between the SLPI and resiquimod pathways in the immune response occurring in allergic asthma have not been fully elucidated. To evaluate the role of SLPI in the development of asthma phenotypes and the effect of resiquimod treatment on SLPI, we assessed airway resistance and inflammatory parameters in the lungs of OVA-induced asthmatic SLPI transgenic and knockout mice and in mice treated with resiquimod. Compared with wild-type mice, allergic SLPI transgenic mice showed a decrease in lung resistance (p < 0.001), airway eosinophilia (p < 0.001), goblet cell hyperplasia (p < 0.001), and plasma IgE levels (p < 0.001). Allergic SLPI knockout mice displayed phenotype changes significantly more severe compared with wild-type mice. These phenotypes included lung resistance (p < 0.001), airway eosinophilia (p < 0.001), goblet cell hyperplasia (p < 0.001), cytokine levels in the lungs (p < 0.05), and plasma IgE levels (p < 0.001). Treatment of asthmatic transgenic mice with resiquimod increased the expression of SLPI and decreased inflammation in the lungs; resiquimod treatment was still effective in asthmatic SLPI knockout mice. Taken together, our study showed that the expression of SLPI protects against allergic asthma phenotypes, and treatment by resiquimod is independent of SLPI expression, displayed through the use of transgenic and knockout SLPI mice.