对虾的不同发育阶段对有机磷农药的敏感性及其机理初探

对硫磷、甲基异柳磷和久效磷对中国对虾无节幼虫、蚤状幼虫、糠虾幼虫、仔虾的２４ｈＬＣ５０分别为６．０、４．０、３．８、１８×１０－３ｍｇ·Ｌ－１;８．０、３．５、３．５、３０×１０－３ｍｇ·Ｌ－１;２４、２４、２４、０．９ｍｇ·Ｌ－１;敌敌畏均为４８×１０－３ｍｇ·Ｌ－１;对硫磷对南美白对虾为８．６、８．２、８．０、２．０×１０－３ｍｇ·Ｌ－１．研究结果表明,对虾的幼虫前期对硫代磷酸酯类农药的抗性强,仔虾及以后各期抗性弱,而各幼虫期对磷酸酯类农药的敏感性基本相同．     

Peroxidase activities and isoenzyme profiles associated with development of avocado (Persea americana,M.) leaves at different ontogenetic stages

Changes in four peroxidase activity fractions (soluble, membrane-bound, as well as ionically and covalently bound) were studied during development of juvenile and adult avocado leaves. Greater differences were found in the soluble fraction with an increase in total activity at the end of the growth phase. In relation to the ontogenetic stages, there were significant variations in the soluble peroxidase activity of both stages, especially in leaves which have already detained their growth, 263 U/g fresh wt in adult leaves vs. 70 U/g fresh wt juvenile leaves. Moreover, the isozyme profile of this fraction revealed the appearance of an anionic band, R_f 0.35, at much earlier stages in juvenile than in adult leaves. Concerning the other three fractions, there were no marked changes in total activity of either membrane-bound or ionically and covalently bound peroxidases. However, in the isoenzyme profiles of the ionically bound fraction of juvenile leaves, three highly cationic bands appeared at much earlier stages than in adult leaves. In avocado, attempts to use leaf peroxidase activity as marker of ontogenetic age must be taken with caution, since great fluctuations related with developmental stages occur in juvenile and adult leaves.     

家兔前体脂肪细胞分化不同时期基因表达谱分析

脂肪的过度积累严重危害人类健康。前体脂肪细胞分化是脂肪发育的关键过程,研究前体脂肪细胞分化相关基因的表达有助于认识脂肪沉积的机理。尽管家兔是一种理想的研究脂肪发育的动物模型,但是针对其前体脂肪细胞分化不同时期基因表达谱的研究鲜见报道。本研究通过诱导家兔前体脂肪细胞分化,在分化第0 d、3 d和9 d收集脂肪细胞,利用转录组测序(RNA-seq),在分化第3 d样本与第0 d样本的比较中筛选出1352个差异表达基因(differentially expressed genes, DEGs),在分化第9 d样本与第3 d样本的比较中筛选出888个DEGs。GO (gene ontology)功能富集和KEGG (kyoto encyclopedia of genes and genomes)通路分析发现,0~3 d分化期上调的DEGs显著富集在PPAR信号通路和PI3K-Akt信号通路上,3~9d分化期上调的DEGs显著富集到与细胞周期调控有关的GO条目和KEGG信号通路,0~3d和3~9d阶段特异上调的DEGs可能分别作用于细胞质和细胞核。通过DEGs的蛋白-蛋白互作(protein-protein interaction, PPI)网络分析发现,筛选出的核心节点(hub node)基因可能通过调控细胞周期而影响家兔前体脂肪细胞分化。     

Nuclear liver glycoproteins at different stages of chicken embryo development

In order to examine whether the patterns of nuclear and chromatin glycoproteins change during development the glycoproteins of foetal and adult chicken liver were investigated. Nuclear and chromatin proteins from both sources were separated by SDS-PAGE, transferred onto Immobilon-P transfer membrane or nitrocellulose and tested for concanavalin A (Con A), Galanthus nivalis agglutinin (GNA) and Aleuria aurantia agglutinin (AAA) binding. Results revealed a similarity in the profiles of nuclear and chromatin glycoproteins recognized by Con A from 14-, 16-, 18-day foetal and adult chicken liver. Generally GNA and AAA reacted more weakly with glycoproteins from foetal liver compared with the same glycoproteins from adult liver.     

Respiration of oranges and grapefruits harvested at different stages of development

Young and unripe oranges and grapefruits stored at 15° or 20° evidenced shortly after harvest a marked increase in respiratory rate, and then a well-defined maximum which was followed by a decrease.     

Changes of dehydrin profiles induced by drought in winter wheat at different developmental stages

Two cultivars of winter wheat (Triticum aestivum L.) differing in their drought tolerance (KTC86211 and ND7532) were subjected to a progressive soil water stress and recovery at four developmental stages. Dehydrins with molecular masses of 45 and 37 kDa were constitutively accumulated during all stages in both genotypes. The 28 kDa dehydrin accumulated exclusively at seedling stage in both genotypes. The 49 and 40 kDa dehydrins accumulated at both tillering and jointing stages but showed a genotype-specific pattern. The content of most dehydrins increased with decreased soil moisture and then decreased during recovery. These results suggest that accumulation pattern of dehydrins during water stress was related to the genotype and developmental stage.     

REST and its corepressors mediate plasticity of neuronal gene chromatin throughout neurogenesis

Regulation of neuronal gene expression is critical to central nervous system development. Here, we show that REST regulates the transitions from pluripotent to neural stem/progenitor cell and from progenitor to mature neuron. In the transition to progenitor cell, REST is degraded to levels just sufficient to maintain neuronal gene chromatin in an inactive state that is nonetheless poised for expression. As progenitors differentiate into neurons, REST and its co-repressors dissociate from the RE1 site, triggering activation of neuronal genes. In some genes, the level of expression is adjusted further in neurons by CoREST/MeCP2 repressor complexes that remain bound to a site of methylated DNA distinct from the RE1 site. Expression profiling based on this mechanism indicates that REST defines a gene set subject to plasticity in mature neurons. Thus, a multistage repressor mechanism controls the orderly expression of genes during development while still permitting fine tuning in response to specific stimuli.     

Tissue-restricted expression of Nrf2 and its target genes in zebrafish with gene-specific variations in the induction profiles

The Keap1-Nrf2 system serves as a defense mechanism against oxidative stress and electrophilic toxicants by inducing more than one hundred cytoprotective proteins, including antioxidants and phase 2 detoxifying enzymes. Since induction profiles of Nrf2 target genes have been studied exclusively in cultured cells, and not in animal models, their tissue-specificity has not been well characterized. In this paper, we examined and compared the tissue-specific expression of several Nrf2 target genes in zebrafish larvae by whole-mount in situ hybridization (WISH). Seven zebrafish genes (gstp1, mgst3b, prdx1, frrs1c, fthl, gclc and hmox1a) suitable for WISH analysis were selected from candidates for Nrf2 targets identified by microarray analysis. Tissue-restricted induction was observed in the nose, gill, and/or liver for all seven genes in response to Nrf2-activating compounds, diethylmaleate (DEM) and sulforaphane. The Nrf2 gene itself was dominantly expressed in these three tissues, implying that tissue-restricted induction of Nrf2 target genes is defined by tissue-specific expression of Nrf2. Interestingly, the induction of frrs1c and gclc in liver and nose, respectively, was quite low and that of hmox1a was restricted in the liver. These results indicate the existence of gene-specific variations in the tissue specificity, which can be controlled by factors other than Nrf2.     

Regulation of Arabidopsis thaliana Ku genes at different developmental stages under heat stress

Ku, a heterodimeric protein consisting of 70- and 80-kDa subunits, is involved in many cellular processes, such as DNA replication, cell cycle regulation and heat shock response. Moreover, the expression of Arabidopsis thaliana Ku genes (AtKu) is modulated by certain plant hormones through several signal transduction pathways. This study investigated how AtKu are regulated by heat stress. AtKu expression in 3-week-old young seedlings was down-regulated by heat stress in a time-dependent manner, as examined using real-time quantitative PCR, GUS reporter systems, and western blotting analysis. Additionally, the heat-induced repression of AtKu was mediated through the abscisic acid (ABA) biosynthetic pathway, as shown by the reversal of AtKu suppression in the ABA biosynthesis mutant, aba3, and by an increase in the ABA level as analyzed by reverse-phase high performance liquid chromatography. Heat stress-induced regulation of AtKu repression also involved ethylene signaling, DNA repair pathways, and fatty acid synthesis. Furthermore, AtKu expression was repressed in stems, rosette leaves, and cauline leaves in 4-5-week-old plants under heat stress, whereas it remained unchanged in roots and primary inflorescence, indicating that heat differentially modulated AtKu expression in distinct tissues of Arabidopsis.     

Effects of conditioned media on porcine embryos at different stages of development

The objective of our study was to determine the effect of conditioning media with homologous porcine uterine cells on the developmental rate of porcine embryos. Cell monolayers were prepared by selective dissection and digestion of sections from the uterus of prepuberal gilts that were primed with PMSG and hCG. Conditioned media were used with 2 type of embryos: 4-cell stage (Experiment 1) or blastocyst stage (Experiment 2). In Experiment 1, embryos were collected surgically by flushing the oviducts, 36 to 48 h following the first of 2 inseminations. Embryos were cultured in Whitten's medium containing 1.5% BSA as a protein source until they attained the 4-cell stage. Embryos at the 4-cell stage were cultured randomly in either Whitten's medium with 1.5% BSA or Whitten's medium with 1.5% BSA that was previously conditioned for 24 h with an endometrial epithelial cell monolayer. Embryos were cultured in 50-microl drops covered with oil in a 38.5 degrees C, 5% CO(2) in air incubator. There was no advantage to using the conditioned media with the 4-cell stage embryos. The embryos were less developed than those cultured in nonconditioned Whitten's medium (P <0.001). In Experiment 2, embryos were cultured at the blastocyst stage. They were recovered the same way as in Experiment 1 and then cultured in Whitten's medium containing 1.5% BSA until they reached the blastocyst stage. At the blastocyst stage (Day 6), embryos were randomly assigned to 1 of the 6 following treatments: Whitten's with 1.5% BSA or Whitten's plus 1.5% BSA that was previously conditioned with endometrial epithelial cell monolayer, TCM-199 containing 0.4% BSA or TCM-199 plus 0.4% BSA that was previously conditioned with endometrial epithelial cell monolayer, finally, TCM-199 containing 10% serum or TCM-199 plus 10% serum that was previously conditioned with endometrial epithelial cell monolayer. Results show that initiation of hatching was significantly enhanced by conditioning the Whitten's media.