不同抗盐机制对柽柳适应盐渍环境的贡献

用含0(对照),50,100,150,200 mmol/L 浓度的NaCl的Hoagland营养液处理短穗柽柳(Tamarix laxa Willd.)扦插苗.结果表明:根际NaCl浓度从50 mmd/L上升到200 mmol/L时,根系对Na 的排斥量从占理论吸收值的87%上升到93%.随着根际NaCl浓度的上升,体内盐分通过盐腺分泌的绝对量始终是增加的.在根际NaCl浓度为50 mmol/L时,植株的泌盐效率最高,随着根际NaCl浓度继续增加,相对分泌能力反而下降.白天吸收到植物体内的Na 有48%～53%在当天就被盐腺分泌出去.Na 总累积量随着根际NaCl浓度增加而增加,总累积与总吸收的比值在0.47～0.52之间.说明,根系拒盐是柽柳最重要的抗盐机制,而盐腺分泌的Na 量相对于柽柳植株地上部积累的Na 量而言可以达到50%.即,泌盐作用对柽柳地上部抗盐能力提供重要贡献.     

甜瓜细菌性果斑病菌致病性突变体筛选与hrcR基因的克隆

 细菌性果斑病(Bacterial Fruit Blotch,BFB)是西瓜和甜瓜的重要病害。本实验从发病甜瓜果实上分离得到致病菌株MH21,经鉴定为燕麦食酸菌西瓜亚种(Acidovorax avenae subsp. citrulli)。利用转座子Mini-Tn5构建MH21菌株的突变体库,Southern印迹杂交结果显示Mini-Tn5在菌株MH21染色体上可随机、单拷贝插入。通过浸种处理甜瓜种子进行突变体的致病性检查,筛选得到1株致病性完全丧失的突变体M543。对M543中转座子插入基因的克隆和测序表明其突变基因为燕麦食酸菌Ⅲ型分泌系统(TTSS)中的保守基因hrcR。推测菌株MH21中hrcR基因编码的蛋白定位于细菌内膜,是分泌通道主要成分之一。hrcR基因互补菌株的致病性检查结果显示其致病力恢复到野生型的84%。研究同时发现hrcR基因突变后MH21菌株丧失了在烟草上诱导过敏性坏死反应的能力。本研究从遗传学角度说明TTSS是西甜瓜果斑病菌致病性的重要因子。     

干旱胁迫对烟草腺毛密度及叶面分泌物的影响

在烤烟整个生育期中,伸根期轻度干旱,其他时期常规栽培,有利于烟株正常生长发育;成熟期轻度干旱,烟株生育期延长,腺毛脱落较少,腺毛密度于移栽80 d后高于常规栽培处理,但与常规栽培相比,成熟期轻度干旱不利于西柏三烯二醇、高级脂肪烃和茄酮等致香物质的形成和转化,烤后烟叶香吃味不如常规栽培处理;烤烟生长发育的任一时期严重干旱,或全生育期干旱都对烟株正常的生长发育和香气物质的形成有不良影响。     

意大利蜜蜂同日龄不同职能工蜂上颚腺的转录组学分析

为揭示意大利蜜蜂哺育蜂上颚腺中蜂王浆合成和分泌相关的分子机制,通过组建人工蜂群收集3日龄工蜂(3 d)、10日龄哺育蜂(10 dN)、10日龄采集蜂(10 dF)、21日龄哺育蜂(21 dN)和21日龄采集蜂(21 dF),利用高效液相色谱技术检测5种不同职能工蜂上颚腺中10-羟基-2-癸烯酸(10-hydroxy-2...     

EGCG防治糖尿病作用及机制研究进展

表没食子儿茶素没食子酸酯(Epigallocatechin gallate,EGCG)是绿茶中的主要活性成分,具有抗癌、抑制肥胖、缓解代谢综合征等功效。本文总结EGCG预防和缓解糖尿病的相关研究,从降血糖功效、胰岛素抵抗、胰岛素分泌、糖尿病常见并发症等方面综合分析和阐述EGCG的作用机制,以期为绿茶缓解代谢综合征研究提供理论支持。     

瘦素的分泌调节及其在动物生产中的应用

瘦素是由脂肪细胞分泌,由肥胖基因编码的一种蛋白质激素,也是一种免疫因子,可以调控动物摄食,体脂代谢,参与多种疾病的调节以及影响生殖和泌乳.文章综述影响瘦素分泌和基因表达的因素及其在动物生产上的应用.     

III型分泌系统是欧美杨溃疡病菌Lonsdalea quercina重要的致病因子

 欧美杨溃疡病是由Lonsdalea quercina(原称Brenneria quercina,Erwinia quercina)引起的一种细菌性病害,2005年首次在我国河南发现,对我国杨树产业造成了严重影响。菌株N-5-1是从河南濮阳自然发病杨树枝条上分离到的致病菌株。根据N-5-1菌株全基因组测序的初步结果分析,发现N-5-1具有完整的III型分泌系统(Type III secretion system,T3SS)。该系统与植物病原菌Erwinia amylovora CFBP1430和Dickeya dadantii 3937的T3SS高度相似,共由26个基因编码,共约23 kb,其中9个为保守的hrc基因。将L. quercina N-5-1菌株T3SS中保守的结构基因hrcV进行缺失突变,生物测定发现ΔhrcV突变体对“中林46杨”(Populus ×euramericana ‘Zhonglin 46’)2年生枝条的致病力明显下降,而互补菌株HBhrcV致病力与野生菌株保持一致。表明该菌中T3SS是病原细菌重要的致病性因子。菌株N-5-1中hrcV基因的突变导致诱导烟草过敏性坏死反应能力丧失,但并没有影响菌株的生长速率、游动性和生物膜的形成。本研究首次证明了L. quercina N-5-1菌株的T3SS是重要的致病因子。     

布鲁氏菌Ⅳ型分泌系统对树突状细胞自噬、胞内生存和炎症反应的影响

为探究Ⅳ型分泌系统在布鲁氏菌(Brucella)感染过程中的作用,深入了解布鲁氏菌Ⅳ型分泌系统在疫苗开发中的潜力,本研究以牛种布鲁氏菌A19疫苗株为研究对象,使用A19 VirB启动子缺失株感染小鼠树突状细胞(DCs),通过菌落计数(CFU)评估Ⅳ型分泌系统对布鲁氏菌黏附侵袭及胞内生存的影响,同时对感染的细胞进行RNA和总蛋白的提取,分别通过实时荧光定量PCR和Western blotting检测自噬基因Beclin-1的转录和表达情况;收集感染后的细胞上清液,利用ELISA检测炎症因子白细胞介素-6(IL-6)和IL-10的分泌水平。黏附侵袭结果显示,布鲁氏菌VirB启动子缺失株与亲本株A19的黏附侵袭水平无显著差异(P>0.05);胞内生存试验发现,感染的4 h,布鲁氏菌VirB启动子缺失株的胞内存活能力显著低于亲本株A19(P<0.05),感染后0、24和48 h极显著低于亲本株A19(P<0.01);实时荧光定量PCR和Western blotting结果显示,感染后4、8和12 h,布鲁氏菌VirB启动子缺失株刺激细胞产生Beclin-1的水平极显著高于亲本株A19(P<0.01);ELISA结果显示,感染后8和12 h,布鲁氏菌VirB启动子缺失株刺激细胞产生IL-6的水平显著高于亲本株A19(P<0.05),而在感染后8和12 h,布鲁氏菌VirB启动子缺失株刺激细胞分泌IL-10的水平显著低于亲本株A19(P<0.05),感染24 h时极显著低于亲本株A19(P<0.01)。综上所述,当VirB启动子缺失后,布鲁氏菌对DCs的黏附侵袭能力并未明显改变,但显著降低了布鲁氏菌在DCs内的存活能力,提升了DCs的自噬水平,促进了DCs IL-6的分泌,抑制了IL-10的分泌。本研究初步探究了布鲁氏菌Ⅳ型分泌系统在感染DCs过程中的生物学作用,为后续布鲁氏菌疫苗改造研究奠定了理论基础。     

The effect of experimental inhibition of gastric acid secretion on curd formation in abomasum and weight gain of calves

Eight Holstein bull calves were divided into two groups; a non-treated control group and a famotidine treated group. Fresh milk was fed twice a day. The experiment was conducted between 7 and 14 days of age. During the experimental period the control group was injected with physiological saline, and the famotidine group was injected with famotidine, a histamine-H2-receptor blocker, into the jugular vein 30 minutes prior to each feeding. The control group showed maximum curd formation 2 h after feeding at both 7 and 14 days of age. Curd scores of 7-day-old and 14-day-old calves were significantly lower in the famotidine than in the control group at 2 and 4 h after feeding. Most fecal samples from the famotidine group exhibited an acidic smell. The famotidine group showed significantly lower values for both average weight gain and the rate of weight gain from 7 to 14 days of age. The inhibition of gastric acid secretion decreased curd formation in the abomasum as well as daily weight gain compared to non-treated control calves. This suggested that curd formation in the abomasum is important for the weight gain of newborn calves.     

Influence of obesity on first-phase insulin secretion in individuals with different glucose tolerance

AIM: To explore the influence of obesity on the first-phase insulin secretion in the individuals with different glucose tolerance. METHODS: Thirty-eight subjects with normal glucose tolerance without family history of diabetes (normal control,NC), 32 subjects with normal glucose tolerance (NGT) who were the first-degree relatives of type 2 diabetic patients, 67 patients with impaired glucose regulation (IGR) and 35 newly-diagnosed type 2 diabetic patients (T2DM) were enrolled in the study. The patients in the 4 groups were further divided into 2 subgroups: overweight/obesity and normal weight subgroups. All subjects received oral glucose-insulin release test (OG-IRT) and intravenous glucose tolerance test (IVGTT). Acute insulin response at 3~5 min (AIR3-5) was used to reflect first-phase insulin secretion,and insulin sensitivity index (ISI) was used to reflect insulin sensitivity. The influence of obesity on the islet β-cell function and insulin sensitivity in the individuals with different glucose tolerance was observed. RESULTS: The level of AIR3-5 in NC overweight/obesity subgroup was significantly higher than that in normal weight subgroup (P<0.05), while there was no significant difference between other subgroups (P>0.05). No significant difference in the level of ISI between the patients of IGR in overweight/obesity subgroup and normal weight subgroup was observed, while in the other 3 overweight/obesity subgroups, ISI was lower than that in normal weight subgroups (P<0.05). ISI was negatively correlated with body mass index and waist circumference in all groups (P<0.05). ISI was also positively correlated with AIR3-5 in NC group and negatively correlated in the other 3 groups (P<0.05). CONCLUSION: The impact of obesity on insulin secretion is not the same in the subjects with different glucose tolerance. With the aggravation of insulin resistance, the first-phase insulin secretion in the subjects with normal glucose tolerance without family history of diabetes increases for compensation, while that in the normal glucose tolerance subjects who are the first-degree relatives of type 2 diabetic patients, the patients with impaired glucose regulation and the type 2 diabetic patients could not increase for compensation.