Internalization of Flax Rust Avirulence Proteins into Flax and Tobacco Cells Can Occur in the Absence of the Pathogen

Translocation of pathogen effector proteins into the host cell cytoplasm is a key determinant for the pathogenicity of many bacterial and oomycete plant pathogens. A number of secreted fungal avirulence (Avr) proteins are also inferred to be delivered into host cells, based on their intracellular recognition by host resistance proteins, including those of flax rust (Melampsora lini). Here, we show by immunolocalization that the flax rust AvrM protein is secreted from haustoria during infection and accumulates in the haustorial wall. Five days after inoculation, the AvrM protein was also detected within the cytoplasm of a proportion of plant cells containing haustoria, confirming its delivery into host cells during infection. Transient expression of secreted AvrL567 and AvrM proteins fused to cerulean fluorescent protein in tobacco (Nicotiana tabacum) and flax cells resulted in intracellular accumulation of the fusion proteins. The rust Avr protein signal peptides were functional in plants and efficiently directed fused cerulean into the secretory pathway. Thus, these secreted effectors are internalized into the plant cell cytosol in the absence of the pathogen, suggesting that they do not require a pathogen-encoded transport mechanism. Uptake of these proteins is dependent on signals in their N-terminal regions, but the primary sequence features of these uptake regions are not conserved between different rust effectors.     

红腹锦鸡和白腹锦鸡卵壳的超微结构

本文报道了锦鸡属——白腹锦鸡和红腹锦鸡卵壳的气孔、外壳膜、锥体层、木栅层的超微结构。并对两者的卵壳进行了比较。     

甘蔗节间伸长过程赤霉素生物合成关键基因的表达及相关植物激素动态变化

以甘蔗(Saccharum officinarum)优良品种桂糖42号(GT42)为研究材料, 分别于未伸长期(9-10叶龄以前) (Ls1)、伸长初期(12-13叶龄) (Ls2)和伸长盛期(15-16叶龄) (Ls3)取甘蔗第2片真叶(自顶部起)对应的节间组织, 测定其赤霉素(GA)、生长素(IAA)、油菜素甾醇(BR)、细胞分裂素(CTK)、乙烯(ETH)和脱落酸(ABA)的含量, 并通过实时荧光定量PCR (qRT-PCR)分析赤霉素合成途径关键基因GA₂₀氧化酶基因(GA20-Oxidase1)、赤霉素受体基因(GID1)和DELLA蛋白编码基因(GAI)的差异表达。结果表明, 在甘蔗伸长期间, GA和IAA含量呈现上升趋势, CTK和ABA含量呈下降趋势, ETH含量先上升后下降, BR含量则变化不明显; GA20-Oxidase1和GID1的表达呈上升趋势, 而GAI的表达则呈下降趋势, 这与相关植物激素的变化基本一致。综上, 甘蔗节间伸长过程主要与GA和IAA相关, 其次为CTK和ABA, 而ETH受到IAA的调控影响节间伸长; 植物激素间通过相互作用调控GA20-Oxidase1、GID1和GAI的表达, 影响GA含量和GA的信号转导过程, 进而影响甘蔗节间的伸长。该研究揭示了甘蔗节间伸长过程中赤霉素生物合成途径和信号转导关键基因的差异表达及植物激素含量的动态变化规律。     

Preparation of cross-linked carboxymethyl chitosan for repairing sciatic nerve injury in rats

A successful nerve regeneration process was achieved with nerve repair tubes made up of 1-ethyl-3(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) cross-linked carboxymethyl chitosan (CM-chitosan) with improved biodegradability. Chitosan has a very slow degradation rate, while the EDC cross-linked CM-chitosan tubes degraded to 30% of original weight during 8 weeks of incubation in lysozyme solution. In vitro cell culture indicated that the CM-chitosan films presented no cytotoxicity to Schwann cells. From in vivo studies using a 10 mm rat sciatic nerve defect model investigated by histomorphometry analysis, the average diameter of the fibers and the average thickness of myelin sheath in the CM-chitosan tubes were 3.7 ± 0.33 and 0.33 ± 0.04 μm, respectively, which demonstrated equivalence to nerve autografts (the current “gold” standard); furthermore, the average fiber density in the CM-chitosan tubes was 20.5 × 10³/mm², which was similar to that of autografts (21 × 10³/mm²) and significantly higher than that of common chitosan tubes (15.3 × 10³/mm²).     

Tricyclic dihydroquinazolinones as novel 5-HT2C selective and orally efficacious anti-obesity agents

Agonists of the 5-HT_2C receptor have been shown to suppress appetite and reduce body weight in animal models as well as in humans. However, agonism of the related 5-HT_2B receptor has been associated with valvular heart disease. Synthesis and biological evaluation of a series of novel and highly selective dihydroquinazolinone-derived 5-HT_2C agonists with no detectable agonism of the 5-HT_2B receptor is described. Among these, compounds (+)-2a and (+)-3c were identified as potent and highly selective agonists which exhibited weight loss in a rat model upon oral dosing.     

枯草杆菌中性蛋白酶天然抑制剂的筛选

用透明因法和福林──酚法筛选了２１种植物中的蛋白酶活性抑制剂,其中来自鼓皮、高粱、玉米和土豆的抑制剂的活性在本研究条件下达５０％以上。进一步研究了麸皮、玉米两种抑制剂在不同温度和ｐＨ值下的稳定性,结果表明,两者的稳定性相差甚远,是两类不同的抑制剂。玉米抑制剂比麸皮抑制剂更稳定。     

Comparative analysis of complete chloroplast genome sequences of two subtropical trees, <Emphasis Type="Italic">Phoebe sheareri</Emphasis> and <Emphasis Type="Italic">Phoebe omeiensis</Emphasis> (Lauraceae)

Phoebe is an economically important genus from the family Lauraceae. It is widely distributed in tropical and subtropical Asia, but systematics of the genus is unclear, and currently there is no species-level phylogeny. Here, we determined the complete chloroplast genome sequences of two species with long-range PCR and next genome sequencing technologies, and identified mutation sites and highly variable regions. These highly variable sites were used to reconstruct the phylogeny. The plastomes of Phoebe sheareri and P. omeiensis were 152, 876, and 152, 855 bp, respectively. Comparative genomic analysis indicated that there are 222 mutation sites including 146 substitutions, 73 indels, and 3 microinversions in both plastomes. Fifty-six single-nucleotide changes were identified in gene-coding regions, and 45 microsatellite sites were found for use in species identification. Fourteen divergence hotspots of 38 variable regions were located. Phylogeny was reconstructed using a Bayesian and maximum likelihood approach for 12 Phoebe species and other five related Lauraceae based on 15 of the highly variable regions including accD-psaI, atpB-rbcL, ndhC-trnV, ndhF-rpl32, petA-psbJ, psaA, psbA-trnH, rbcL, rps8-rpl14, rps16-trnQ, rpl32-trnL, trnC-petN, trnL-trnF, trnS-trnG, and ycf1 indicated that variability in the chloroplast regions proposed as variable is enough to detect divergence events among 12 taxa of Phoebe, and that maybe also useful to help to elucidate further relationships among other taxa of the genus.     

Evidence for both the nucleus and cytoplasm as subcellular sites of pathogenesis in Huntington's disease in cell culture and in transgenic mice expressing mutant huntingtin.

A unifying feature of the CAG expansion diseases is the formation of intracellular aggregates composed of the mutant polyglutamine-expanded protein. Despite the presence of aggregates in affected patients, the precise relationship between aggregates and disease pathogenesis is unresolved. Results from in vivo and in vitro studies of mutant huntingtin have led to the hypothesis that nuclear localization of aggregates is critical for the pathology of Huntington's disease (HD). We tested this hypothesis using a 293T cell culture model system by comparing the frequency and toxicity of cytoplasmic and nuclear huntingtin aggregates. Insertion of nuclear import or export sequences into huntingtin fragments containing 548 or 151 amino acids was used to reverse the normal localization of these proteins. Changing the subcellular localization of the fragments did not influence their total aggregate frequency. There were also no significant differences in toxicity associated with the presence of nuclear compared with cytoplasmic aggregates. These studies, together with findings in transgenic mice, suggest two phases for the pathogenesis of HD, with the initial toxicity in the cytoplasm followed by proteolytic processing of huntingtin, nuclear translocation with increased nuclear concentration of N-terminal fragments, seeding of aggregates and resultant apoptotic death. These findings support the nucleus and cytosol as subcellular sites for pathogenesis in HD.     

Deep Whole-Genome Sequencing of 100 Southeast Asian Malays

Whole-genome sequencing across multiple samples in a population provides an unprecedented opportunity for comprehensively characterizing the polymorphic variants in the population. Although the 1000 Genomes Project (1KGP) has offered brief insights into the value of population-level sequencing, the low coverage has compromised the ability to confidently detect rare and low-frequency variants. In addition, the composition of populations in the 1KGP is not complete, despite the fact that the study design has been extended to more than 2,500 samples from more than 20 population groups. The Malays are one of the Austronesian groups predominantly present in Southeast Asia and Oceania, and the Singapore Sequencing Malay Project (SSMP) aims to perform deep whole-genome sequencing of 100 healthy Malays. By sequencing at a minimum of 30× coverage, we have illustrated the higher sensitivity at detecting low-frequency and rare variants and the ability to investigate the presence of hotspots of functional mutations. Compared to the low-pass sequencing in the 1KGP, the deeper coverage allows more functional variants to be identified for each person. A comparison of the fidelity of genotype imputation of Malays indicated that a population-specific reference panel, such as the SSMP, outperforms a cosmopolitan panel with larger number of individuals for common SNPs. For lower-frequency (<5%) markers, a larger number of individuals might have to be whole-genome sequenced so that the accuracy currently afforded by the 1KGP can be achieved. The SSMP data are expected to be the benchmark for evaluating the value of deep population-level sequencing versus low-pass sequencing, especially in populations that are poorly represented in population-genetics studies.     

SPOCK1 promotes the invasion and metastasis of gastric cancer through Slug‐induced epithelial‐mesenchymal transition

Metastasis is a crucial impediment to the successful treatment for gastric cancer. SPOCK1 has been demonstrated to facilitate cancer metastasis in certain types of cancers; however, the role of SPOCK1 in the invasion and metastasis of gastric cancer remains elusive. SPOCK1 and epithelial‐mesenchymal transition (EMT)‐related biomarkers were detected by immunohistochemistry and Western blot in gastric cancer specimens. Other methods including stably transfected against SPOCK1 into gastric cancer cells, Western blot, migration and invasion assays in vitro and metastasis assay in vivo were also performed. The elevated expression of SPOCK1 correlates with EMT‐related markers in human gastric cancer tissue, clinical metastasis and a poor prognosis in patients with gastric cancer. In addition, knockdown of SPOCK1 expression significantly inhibits the invasion and metastasis of gastric cancer cells in vitro and in vivo, inversely, SPOCK1 overexpression results in the opposite effect. Interestingly, SPOCK1 expression has no effect on cell proliferation in vitro and in vivo. Regarding the mechanism(s) of SPOCK1‐induced cells invasion and metastasis, we prove that Slug‐induced EMT is involved in SPOCK1‐facilitating gastric cancer cells invasion and metastasis. The elevated SPOCK1 expression is closely correlated with cancer metastasis and patient survival, and SPOCK1 promotes the invasion and metastasis of gastric cancer through Slug‐mediated EMT, thereby possibly providing a novel therapeutic target for gastric cancer.