四川省缙云山常绿阔叶林的数量分类

本文报道了用无样抽样的中点方角法对四川省缙云山常绿阔叶林的中、低级分类单位的数量分类研究。分类中,根据乔木层重要值特征确定建群种,划分出5个群系。以次要层(灌木层)种群重要值特征找出优势种区分出8个群丛组,然后用相同的方法分析草本层,找出草本层优势种,确定群丛。研究证明数量分类方法在常绿阔叶林的中、低级分类单位是适用的。     

Jingzhaotoxin-I, a novel spider neurotoxin preferentially inhibiting cardiac sodium channel inactivation

Jingzhaotoxin-I (JZTX-I), a 33-residue polypeptide, is derived from the Chinese tarantula Chilobrachys jing-zhao venom based on its ability to evidently increase the strength and the rate of vertebrate heartbeats. The toxin has three disulfide bonds with the linkage of I-IV, II-V, and III-VI that is a typical pattern found in inhibitor cystine knot molecules. Its cDNA determined by rapid amplification of 3'- and 5'-cDNA ends encoded a 62-residue precursor with a small proregion of eight residues. Whole-cell configuration indicated that JZTX-I was a novel neurotoxin preferentially inhibiting cardiac sodium channel inactivation by binding to receptor site 3. Although JZTX-I also exhibits the interaction with channel isoforms expressing in mammalian and insect sensory neurons, its affinity for tetrodotoxin-resistant subtype in mammalian cardiac myocytes (IC50 = 31.6 nm) is approximately 30-fold higher than that for tetrodotoxin-sensitive subtypes in latter tissues. Not affecting outward delay-rectified potassium channels expressed in Xenopus laevis oocytes and tetrodotoxin-resistant sodium channels in mammal sensory neurons, JZTX-I hopefully represents a potent ligand to discriminate cardiac sodium channels from neuronal tetrodotoxin-resistant isoforms. Furthermore, different from any reported spider toxins, the toxin neither modifies the current-voltage relationships nor shifts the steady-state inactivation of sodium channels. Therefore, JZTX-I defines a new subclass of spider sodium channel toxins. JZTX-I is an alpha-like toxin first reported from spider venoms. The result provides an important witness for a convergent functional evolution between spider and other animal venoms.     

Up-regulation of DNA2 results in cell proliferation and migration in endometriosis

Journal of Molecular Histology - Accumulating evidence has suggests that women with advanced endometriosis exhibit alterations in the expression of genes in the endometrium compared to healthy...     

Efficient simulation under a population genetics model of carcinogenesis

MOTIVATION: Cancer is well known to be the end result of somatic mutations that disrupt normal cell division. The number of such mutations that have to be accumulated in a cell before cancer develops depends on the type of cancer. The waiting time T(m) until the appearance of m mutations in a cell is thus an important quantity in population genetics models of carcinogenesis. Such models are often difficult to analyze theoretically because of the complex interactions of mutation, drift and selection. They are also computationally expensive to simulate because of the large number of cells and the low mutation rate. RESULTS: We develop an efficient algorithm for simulating the waiting time T(m) until m mutations under a population genetics model of cancer development. We use an exact algorithm to simulate evolution of small cell populations and coarse-grained τ-leaping approximation to handle large populations. We compared our hybrid simulation algorithm with the exact algorithm in small populations and with available asymptotic results for large populations. The comparison suggested that our algorithm is accurate and computationally efficient. We used the algorithm to study the waiting time for up to 20 mutations under a Moran model with variable population sizes. Our new algorithm may be useful for studying realistic models of carcinogenesis, which incorporates variable mutation rates and fitness effects.     

Molecular Detection of Novel Anammox Bacterial Clusters in the Sediments of the Shallow Freshwater Lake Taihu

Previous studies have demonstrated the wide occurrence of anaerobic ammonium oxidizing (anammox) bacteria; however, there is very limited information on the distribution of these bacteria in freshwater habitats. In this study, the anammox bacterial communities were detected by molecular analysis targeting the 16S rRNA genes in the sediments of Lake Taihu, a large and shallow eutrophic freshwater lake in China. The recovery of specific 16S rRNA sequences with two stable monophyletic clusters indicated that anammox bacteria were present in Lake Taihu. A phylogenetic analysis indicated that these two groups represent two novel lineages within the first subgroup of anammox bacteria, independent of the treeing methods. High intra-lake variability in anammox bacterial diversity and community composition was observed, in particular, based on a 1% cut-off of 16S rRNA sequence variation. The spatial variability was largely related to the substrate availability, which was denoted by the correlations between the relative abundance of the two Taihu anammox bacterial groups and the concentrations of ammonium and nitrite. This indicates that the niche differentiation of anammox bacteria is linked to the environmental heterogeneity. These findings suggest that the freshwater lakes may accommodate different anammox bacterial communities and, thus, expand our knowledge on the diversity and distribution of anammox bacteria. Supplemental materials are available for this article. Go to the publisher's online edition of Geomicrobiology Journal to view the free supplemental files.     

Overexpression of ALDH2B8, an aldehyde dehydrogenase gene from grapevine, sustains Arabidopsis growth upon salt stress and protects plants against oxidative stress

Aldehyde dehydrogenases (ALDHs) belong to a family of NAD (P)⁺-dependent enzymes that catalyze the oxidation of various toxic aldehydes to carboxylic acids. They have been reported to play important roles in plant responses to various stresses. Here we report on the isolation of a grapevine ALDH gene, which is rapidly induced in response to NaCl treatment. When transiently expressed in Arabidopsis protoplasts, grapevine ALDH2B8 was found to be localized in mitochondria. Transgenic Arabidopsis plants overexpressing grapevine ALDH2B8 showed sustained growth upon salt stress and increased tolerance against oxidative stress, which was correlated with decreased accumulation of reactive oxygen specie and malondialdehyde derived from cellular lipid peroxidation. In addition, the transgenic line had longer roots and higher chlorophyll content than the wild type under high salinity conditions. Taken together, we suggest that grapevine ALDH2B8 is involved in plant responses to oxidative and salt stress.     

Triptolide improves spinal cord injury by promoting autophagy and inhibiting apoptosis

We investigated the effect of triptolide (TP) on spinal cord injury (SCI), and its underlying mechanism. Following the establishment of the SCI model using YFP H‐line transgenic mice, TP was intraperitoneally injected at a dose of 0.2 mg/kg once daily for 7 days. Behavioral tests, Nissl staining, and hematoxylin–eosin staining were employed to assess motor function recovery and neuronal cell death. Western blot and immunofluorescence staining were used to assess autophagy‐associated proteins (LC3B, p62, Beclin‐1) and the apoptosis‐associated proteins (Bcl‐2, caspase‐3, Bax). The TP‐treated group showed improved motor functions, and reduced neuronal cell death. Also, significant upregulation of Bcl‐2 and LC3B expressions, with the downregulation of p62, Bax and caspase‐3 expressions were found in the TP‐treated group. Additionally, phosphorylation of extracellular signal‐regulated protein kinases 1 and 2 (ERK1 and ERK2) was decreased in the TP‐treated group. TP mediates its protective effect in SCI by promoting the autophagic pathway while inhibiting the MAPK/ERK1/2 signaling pathway. These results demonstrate the therapeutic potential of TP in SCI.     

Genome‐wide association study identifies an NLR gene that confers partial resistance to Magnaporthe oryzae in rice

Because of the frequent breakdown of major resistance (R) genes, identification of new partial R genes against rice blast disease is an important goal of rice breeding. In this study, we used a core collection of the Rice Diversity Panel II (C‐RDP‐II), which contains 584 rice accessions and are genotyped with 700 000 single‐nucleotide polymorphism (SNP) markers. The C‐RDP‐II accessions were inoculated with three blast strains collected from different rice‐growing regions in China. Genome‐wide association study identified 27 loci associated with rice blast resistance (LABRs). Among them, 22 LABRs were not associated with any known blast R genes or QTLs. Interestingly, a nucleotide‐binding site leucine‐rich repeat (NLR) gene cluster exists in the LABR12 region on chromosome 4. One of the NLR genes is highly conserved in multiple partially resistant rice cultivars, and its expression is significantly up‐regulated at the early stages of rice blast infection. Knockout of this gene via CRISPR‐Cas9 in transgenic plants partially reduced blast resistance to four blast strains. The identification of this new non‐strain specific partial R gene, tentatively named rice blast Partial Resistance gene 1 (PiPR1), provides genetic material that will be useful for understanding the partial resistance mechanism and for breeding durably resistant cultivars against blast disease of rice.