Variation in egg mass within two Atlantic herring Clupea harengus stocks

The main objective of this study was to investigate if egg size (mass) at spawning is invariant for Scotia-Fundy summer and autumn (SFSH) and Icelandic summer (ISSH) spawning herring Clupea harengus. Oocyte dry mass measurements for SFSH females collected in 2001 and ISSH females collected in 1999 and 2000 showed a large variation. Difference in egg dry mass among fish was found to vary by as much as twofold in each stock. For ISSH, variation in egg mass was also apparent from oocyte volume measurements made jointly with a histological examination of the ovaries. Approximately 20% of the variation in egg mass could be explained by maternal whole-body mass or total length, indicating that length or age composition in the stocks can potentially influence the recruitment success. This implies that fisheries management strategies should aim to maintain a broad range in age composition.     

Case of a stronger capability of maize seedlings to use ammonium being responsible for the higher 15N recovery efficiency of ammonium compared with nitrate

Plant and Soil - Biocrusts are important functional units in dryland ecosystems. Regarded as ecosystem engineers, cyanobacteria in biocrusts contribute several major physico-chemical and biological...     

Characterization of NPR1 and NPR4 genes from mulberry (Morus multicaulis) and their roles in development and stress resistance

The quality and quantity of mulberry leaves are often affected by various environmental factors. The plant NPR1 and its homologous genes are important for plant systemic acquired resistance. Here, the full‐length cDNAs encoding the NPR1 and NPR4 genes (designated MuNPR1 and MuNPR4, respectively) were isolated from Morus multicaulis. Sequence analysis of the amino acids and protein modeling of the MuNPR1 and MuNPR4 proteins showed that MuNPR1 shares some conserved characteristics with its homolog MuNPR4. MuNPR1 was shown to have different expression patterns than MuNPR4 in mulberry plants. Interestingly, MuNPR1 or MuNPR4 transgenic Arabidopsis produced an early flowering phenotype, and the expression of the pathogenesis‐related 1a gene was promoted in MuNPR1 transgenic Arabidopsis. The MuNPR1 transgenic plants showed more resistance to Pseudomonas syringae pv. tomato DC3000 (Pst. DC3000) than did the wild‐type Arabidopsis. Moreover, the ectopic expression of MuNPR1 might lead to enhanced scavenging ability and suppress collase accumulation. In contrast, the MuNPR4 transgenic Arabidopsis were hypersensitive to Pst. DC3000 infection. In addition, transgenic Arabidopsis with the ectopic expression of either MuNPR1 or MuNPR4 showed sensitivity to salt and drought stresses. Our data suggest that both the MuNPR1 and MuNPR4 genes play a role in the coordination between signaling pathways, and the information provided here enables the in‐depth functional analysis of the MuNPR1 and MuNPR4 genes and may promote mulberry resistance breeding in the future.     

Effects of Melatonin on Growth,Physiology and Gene Expression in Rice Seedlings Under Cadmium Stress

Melatonin (MLT) is a hormonal substance found in many organisms and can improve plant stress resistance. In this study, the japonica rice variety Y32 and indica rice variety NJ6 were cultivated in hydroponics under different concentrations of CdCl₂ at the two-leaf stage. The growth, physiological and biochemical responses of the seedlings and the expression of cadmium (Cd)-related genes under exogenous melatonin (MLT) treatment were assessed. The results indicated that Cd stress destroyed the dynamic balance between reactive oxygen species (ROS) production and removal, resulting in ROS accumulation, membrane lipid peroxidation, and impaired growth and development. Following the application of exogenous MLT to rice seedlings, increases in plant biomass including both underground and above-ground areas were observed. MLT also scavenged the inhibition of superoxide dismutase (SOD) and peroxidase (POD) in a concentration dependent manner in response to Cd stress. Catalase (CAT) activity and malondialdehyde (MDA) expression also decreased following MLT treatment. Amongst the six Cd-related genes assessed, five genes were down-regulated and one was up-regulated in response to MLT treatment. Taken together, these data demonstrate that MLT improves the resilience of rice seedlings at the biochemical, physiological, and molecular levels, and diminishes the damage caused by Cd stress.     

A non-secreted plant defensin AtPDF2.6 conferred cadmium tolerance via its chelation in Arabidopsis

Plant Molecular Biology - Plant defensin AtPDF2.6 is not secreted to the apoplast and localized in cytoplasm. AtPDF2.6 is mainly expressed in root vascular bundles of xylem parenchyma cell, and...     

猪链球菌2型感染仔猪致脑炎模型的建立

【背景】猪链球菌2型(Streptococcus suis type 2)是危害养猪业重要的病原,给我国养猪业造成了重大的损失,迄今为止仍缺乏猪链球菌2型感染仔猪致脑炎模型,建立合适的模型用于临床药物研发及机制研究为防控该病奠定基础。【目的】构建猪链球菌2型感染仔猪致脑炎模型,通过观察感染仔猪的临床变化、病理学变化、病原分离及PCR鉴定证实模型构建成功。【方法】选取6头健康的三元杂交猪仔猪,随机均分为A、B两组。A组仔猪接种猪链球菌,B组接种生理盐水作为空白对照,观察A组仔猪的临床症状、剖检变化、病理组织学变化。【结果】A组仔猪出现体温升高、精神沉郁、嗜睡以及严重的神经症状,甚至死亡;器官出现严重病变,如脊髓和大脑的神经元细胞的肿胀、坏死、溶解,小脑灰质区浦肯野细胞层和颗粒层见细胞灶状坏死并形成坏死后空腔。【结论】成功构建出猪链球菌2型感染仔猪的脑炎模型。