油菜叶片蛋白质组对机械损伤应答的初步分析

 植物在对抗昆虫的长期进化过程中形成了自我防御机制,能够产生特异的抗性蛋白来应对昆虫的取食。该文用机械损伤模拟害虫取食,研究和 对比了油菜(Brassica napus cv. Westar)在机械损伤前后可溶性总蛋白的含量变化并试图通过蛋白质组学技术来检测可能发生变化的蛋白质。 蛋白质定量检测发现,同一植株同一叶片损伤前后可溶性总蛋白含量差异显著,损伤后蛋白表达量增高。 蛋白质双向凝胶电泳及其差异显示分 析损伤前后的蛋白质组,表明有8个蛋白质点发生明显的上调或下调。选择其中2个差异蛋白点经过MALDI-TOF质谱鉴定,它们分别是Rubisco小 亚基前体、果糖-1,6-二磷酸醛缩酶和粪卟啉-3-氧化酶,这些蛋白质可能在油菜叶片应答机械损伤过程中对维持植物的生理功能起到重要作用 。     

The mechanism of background extinction

Following publication of On the Origin of Species, biologists concentrated on and resolved the mechanisms of adaptation and speciation, but largely ignored extinction. Thus, extinction remained essentially a discipline of palaeontology. Adequate language is not available to describe extinction phenomena because they must be discussed in the passive voice, wherein populations simply ‘go extinct’ without reference to process, specifics, effects, or causality. Extinction is also described typically in terms of its dynamics (including rate or risk), and although correlative variables enhance our ability to predict extinction, they do not necessarily enable an understanding of process. Yet background extinction, like evolution, is a process requiring a functional explanation, without which it is impossible to formulate mechanisms. We define the mechanism of background extinction as a typically long‐term, multi‐generational loss of reproductive fitness. This simple concept has received little credence because of a perception that excess generation of progeny ensures population sustainability, and perhaps the misconception that the loss of reproductive fitness somehow constitutes selection against reproduction itself. During environmental shifts, reproductive fitness is compromised when biotic or abiotic extremes consistently exceed existing norms of reaction. Subsequent selection will now favour individual survival over reproductive fitness, initiating long‐term negative selection pressure and population decline. Background extinction consists typically of two intergrading phases: habitat attenuation and habitat dissolution. These processes generate the relict populations that characterize many species undergoing background extinction. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 255–268.     

Myelin isolation: comparison of sedimentation and flotation techniques.

Brains from young (20 day old) and adult rats were used to compare myelin yields obtained by sedimentation and flotation techniques. The flotation method consistently gave approx 70% higher yields of myelin than the sedimentation method. Both myelin preparations have virtually identical protein composition as assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Electrophoretic analysis revealed substantial concentrations of myelin proteins in the non-myelin particulate fraction obtained by the sedimentation but not by the flotation method. The study indicates that the paradigm of the sedimentation method results in a significant loss of myelin during isolation, and that this loss can be avoided or minimized by employing the flotation method.     

Preservation of murine embryos in a state of dormancy at 4C

With the aim ofimproving preservation of blood products and organs fortransplantation, we designed solutions to induce a state of dormancy incells and tissues at 4°C. The solutions were devoid of combinationsof ions (e.g., K⁺,Rb⁺,Cs⁺, andNH⁺₄ withHCO₃,H₂PO₄, andCl) that are believed tobreak down low-density water in the entrance compartments of ionchannels, resulting in cyclical open states (normal water) and closedstates (low-density water). The total osmolality was always0.29-0.3 osmol/kgH₂O, made upof combinations of a di- or trisaccharide, a compatible solute, sodiumsulfate, citrate, or chloride, and 1.75 mMCaCl₂. The end point was the ability of murine embryos to progress to hatching in culture after preservation in such a solution at 4°C. Embryos hatched after 5 or6 days in some preservative solutions compared with 1-3 days inmost saline solutions; survival was improved by pretreatment withsodium butyrate.     

Behavioural thermoregulation in Daphnia carinata from different depths of a natural water body: influence of environmental oxygen levels and temperature

The influence of environmental parameters (water temperature and dissolved oxygen content) on the haemoglobin content of a naturally occurring population of Daphnia carinata was studied in a population resident in an intermittently flowing, shallow body of water. It was found that the Hb content of the animals was influenced by a combination of both the water temperature and dissolved oxygen profiles of the water body. In Summer, stratification, as indicated by sampling at three depths, constrained thermoregulatory behaviour; Hb-poor animals from the upper levels of the water column chose a lower temperature in hypoxia than their Hb-rich counterparts from greater depth. In Winter, the water column was mixed and remained moderately hypoxic at all times. Due to the low temperature of the water, Hb-contents in winter were much lower than those found in Summer. Overall, it was found that thermoregulatory behaviour in D. carinata is dependent upon Hb-content, which is strongly influenced by the animals' environment.     

The influence of haemoglobin on behavioural thermoregulation and oxygen consumption in Daphnia carinata

When placed in a temperature gradient, most ectotherms have a strict thermal preference that is lowered on exposure to hypoxia. Branchiopods, small aquatic crustaceans, are known to synthesise haemoglobin (Hb) when exposed to hypoxia; hypoxia can occur diurnally and seasonally in ponds. The effect of Hb on behavioural thermoregulation in the branchiopod Daphnia carinata following exposure to both normoxia and hypoxia was examined. Control animals raised in normoxia (Po2=150 mmHg, [Hb]=0.026+/-0.007 mg g dry wt-1) and Hb-rich animals raised in hypoxia (Po2=70 mmHg, [Hb]=0.080+/-0.017 mg g dry wt-1) were placed (N=30) in a tube (length=500 mm, diameter=8 mm) filled with pond water. In the absence of a thermal gradient, control and Hb-rich animals in normoxic water were uniformly distributed along the tube. The presence of a thermal gradient (13 degrees -28 degrees C) elicited clustering at a preferred temperature, T approximately 23 degrees C for both groups. Exposure to hypoxic water in a thermal gradient resulted in a behavioural shift: T approximately 16 degrees C for controls and T approximately 19 degrees C for Hb-rich animals. Measurements of oxygen consumption (V&d2;o2) at fixed temperatures revealed that Hb is associated with a metabolic acclimation to hypoxia.     

人脂肪间充质干细胞外泌体通过上调β-catenin、c-Myc和细胞周期蛋白表达促进表皮干细胞增殖

本研究探讨人脂肪间充质干细胞来源的外泌体(ADSC-Exos)对人表皮干细胞(EpSCs)增殖的影响及机制.首先使用Ⅰ型胶原酶分离人脂肪组织ADSCs,中性蛋白酶Ⅱ和胰酶分离人皮肤组织EpSCs;采用ExoQuick-TC试剂分离ADSCs培养上清中的外泌体.然后通过MTT法、细胞免疫荧光检测Ki67,BrdU掺入实验检测ADSC-Exos对EpSCs增殖的影响,流式细胞术检测ADSC-Exos对EpSCs细胞周期的影响.通过H&E染色、免疫组化染色检测细胞增殖标志分子及表皮干细胞标志分子的表达,以观察ADSC-Exos对体外培养皮肤组织的结构及EpSCs增殖的影响.结果显示:ADSC-Exos能以浓度依赖性和时间依赖性的方式促进EpSCs增殖,增加S期细胞数,减少G1期细胞数;ADSC-Exos也能促进体外培养皮肤组织中的EpSCs增殖.机制研究发现:ADSC-Exos对EpSCs的促增殖作用能部分被β-catenin抑制剂XAV-939或c-Myc抑制剂10058-F4所抑制.ADSC-Exos能促进EpSCs表达β-catenin、c-Myc及cyclin E1、A2、D...     

Molecular and genomic basis of volatile-mediated indirect defense against insects in rice

Rice plants fed on by fall armyworm ( Spodoptera frugiperda , FAW) caterpillars emit a blend of volatiles dominated by terpenoids. These volatiles were highly attractive to females of the parasitoid Cotesia marginiventris . Microarray analysis identified 196 rice genes whose expression was significantly upregulated by FAW feeding, 18 of which encode metabolic enzymes potentially involved in volatile biosynthesis. Significant induction of expression of seven of the 11 terpene synthase ( TPS ) genes identified through the microarray experiments was confirmd using real-time RT-PCR. Enzymes encoded by three TPS genes, Os02g02930, Os08g07100 and Os08g04500, were biochemically characterized. Os02g02930 was found to encode a monoterpene synthase producing the single product S- linalool, which is the most abundant volatile emitted from FAW-damaged rice plants. Both Os08g07100 and Os08g04500 were found to encode sesquiterpene synthases, each producing multiple products. These three enzymes are responsible for production of the majority of the terpenes released from FAW-damaged rice plants. In addition to TPS genes, several key genes in the upstream terpenoid pathways were also found to be upregulated by FAW feeding. This paper provides a comprehensive analysis of FAW-induced volatiles and the corresponding volatile biosynthetic genes potentially involved in indirect defense in rice. Evolution of the genetic basis governing volatile terpenoid biosynthesis for indirect defense is discussed.