硒和维生素E在热应激猪自由基代谢中的作用

在平均温度为 (34.89± 5 .6 2 )℃的猪舍内 ,选择 10 0日龄长大二元杂交商品生长猪 (去势公猪 ) 4 0头 ,随机分为 4组 ,通过日粮添加不同水平的硒 (Se)和维生素 E(VE)作为对照组、低水平组、中水平组和高水平组 ,测定与自由基代谢有关的血清丙二醛 (malondialdehyde,MDA )含量、超氧化物歧化酶 (superoxide dismutase,SOD)、谷胱甘肽过氧化物酶 (glutathione- peroxidase,GSH- Px)活性。结果表明 ,补充 Se和 VE 可降低 (P<0 .0 5 )或显著降低 (P<0 .0 1)血清MDA含量 ;升高 (P<0 .0 5 )或显著升高 (P<0 .0 1)血清 SOD和 GSH- Px活性 ,从而证明 Se和 VE可减少热应激猪体内自由基的数量 ,缓解猪热应激时的自由基损伤 ,提高猪抗热应激的能力     

铅胁迫对金丝草生长及生理生化的影响

采用土培方法,探究不同梯度铅胁迫(0、1000、2000和3000 mg·kg^-1)对金丝草生长形态、体内抗氧化系统和渗透调节物质的影响。结果表明:低浓度(1000 mg·kg^-1)处理会诱导金丝草叶片过氧化物酶(POD)活性、可溶性蛋白(SP)含量和根系抗超氧阴离子自由基活力(ASAFR)、可溶性糖(SS)及脯氨酸(Pro)含量增加,使得金丝草植株总抗氧化能力(T-AOC)处于较高水平,促进了金丝草株高、叶长和生物量的增加。随胁迫浓度增加,高浓度(2000~3000 mg·kg^-1)处理下,金丝草叶片和根系丙二醛(MDA)含量迅速增加,株高、叶长、叶面积和生物量下降,生长受到抑制。但金丝草通过增强叶片和根系POD、过氧化氢酶(CAT)活性来抵御过氧化作用,提高可溶性蛋白和可溶性糖含量维持细胞正常运作,增加根系生物量占比来加强根系发育,一定程度适应了高浓度铅胁迫。综上表明,金丝草主要通过叶片和根系不同抗氧化酶差异化响应、提高渗透调节物质含量,提升金丝草植株总抗氧化能力等途径来提高Pb耐性,对Pb污染矿区植物修复有较大潜力。     

NO介导的Ca2+信号对渗透胁迫下紫花苜蓿幼苗光合特征及抗性的影响

以紫花苜蓿幼苗为材料,用聚乙二醇(PEG-6000)作为渗透介质人工模拟干旱条件,外源喷施NO供体硝普钠(SNP)、钙信号试剂CaCl₂、NO抑制剂亚甲基蓝(MB)和Ca²⁺通道阻断剂LaCl₃,对紫花苜蓿幼苗光合特征、抗氧化酶活性及过氧化物酶(POD)同工酶图谱进行研究,探讨了渗透胁迫下NO介导的Ca²⁺信号对紫花苜蓿幼苗光合作用及抗氧化能力的影响。结果表明:在渗透胁迫条件下,施加SNP、CaCl₂均能够有效缓解叶片叶绿素a、类胡萝卜素及总叶绿素含量降低,提高叶片净光合速率(P_n)、气孔导度(G_s)及气孔限制值(L_s),而对胞间CO₂浓度(C_i)没有缓解作用。SNP、CaCl₂及SNP+CaCl₂处理提高了幼苗叶片中抗氧化酶活性和脯氨酸含量,降低了丙二醛(MDA)含量。其中共处理时效果最为显著,第4天 SOD、POD、CAT活性较PEG处理升高了39.29%、30.41%和56.24%,脯氨酸含量增加了45.59%,MDA含量降低了45.59%。POD同工酶图谱在第4天时酶谱带数最多,POD活性最强,且SNP+CaCl₂共处理下出现新酶带。而添加外源NO的同时添加Ca²⁺通道阻断剂LaCl₃,紫花苜蓿幼苗光合速率、抗氧化酶活性及脯氨酸含量均降低,丙二醛含量增加,添加Ca²⁺信号的同时施加NO抑制剂MB也具有相同的作用,说明Ca²⁺信号参与NO信号转导过程并相互作用共同调节渗透胁迫下紫花苜蓿幼苗的生理应答响应。     

人工改造野生大豆GsDREB2基因对植物耐盐和耐渗透胁迫能力的影响

DREB (dehydration responsive element binding protein)转录因子是一个干旱应答元件的结合蛋白,它能特异结合启动子中含有DRE/CRT顺式元件,激活逆境诱导基因的表达,调控植物对干旱、低温、高盐、高温等胁迫的耐逆性。大量研究表明DREB转录因子在信号传导、作用机理及基因表达方面存在复杂性。为了野生大豆来源GsDREB2基因能更有效地发挥功能,人工突变该基因的负向调节结构域(negative regulatory domain, NRD,140~204),经改造命名为GsDREB2-mNRD。在酵母中比较全长基因(FLDREB2)和GsDREB2-mNRD转录激活和与DRE元件结合的能力,并验证GsDREB2-mNRD核定位情况。分别将FLDREB2和GsDREB2-mNRD转化拟南芥,通过拟南芥幼苗期盐胁迫和渗透胁迫试验,比较GsDREB2-mNRD和FLDREB2在提高植物耐盐和渗透胁迫方面的差异。结果表明,GsDREB2基因内部存在着负向调节结构域(NRD),抑制了GsDREB2转录激活功能和DRE元件结合的特性;经改造的GsDREB2基因依然能定位在细胞核;超量表达GsDREB2-mNRD基因的拟南芥耐盐和渗透胁迫能力明显强于非转基因对照,也高于FLDREB2基因超表达的拟南芥;野生大豆来源的GsDREB2基因NRD结构域的缺失可增强该基因在植物耐盐、渗透胁迫等逆境胁迫下的功能。     

低温胁迫对狗牙根生理及基因表达的影响

以耐寒性差异较大的杂交狗牙根品种运动百慕大、天堂419和普通狗牙根品种保定狗牙根为试验材料,分析了昼夜温度为适温(30 ℃/25 ℃)、亚适温(18 ℃/12 ℃)、冷害(8 ℃/4 ℃)和冻害(4 ℃/-4 ℃)4种温度处理下,低温对狗牙根生长速率和草坪质量、MDA含量、叶绿素荧光(F_v/F_m)、光合作用(P_n、G_s、C_i、T_r)、H₂O₂和O2·-含量、抗氧化酶活性(SOD、POD、CAT、APX)、抗氧化酶及耐寒相关基因(CBF1、COR、LEA)表达的影响。结果表明,随着温度的降低,狗牙根草坪质量、生长速率、F_v/F_m和光合作用显著下降,但在耐寒性强的运动百慕大中下降幅度较小;低温下叶片MDA和H₂O₂含量及O2·-产生速率显著升高,其中在耐寒性弱的保定狗牙根中升高程度更大;狗牙根叶片抗氧化酶活性及抗氧化酶基因的表达水平随着处理温度的下降而显著升高,其中在运动百慕大中更为明显;狗牙根CBF1、COR和LEA基因表达量随着温度的下降而显著升高,尤其是在耐寒狗牙根运动百慕大中更为显著。低温诱导的抗氧化酶和耐寒相关基因上调表达,增强了细胞内的抗氧化防御,有助于狗牙根植株维持较高的光合作用和细胞膜稳定性,延缓叶片的衰老,从而提高了狗牙根的抗寒能力。     

土壤易氧化有机碳与溶解性有机碳对荒漠草地沙漠化过程中土壤碳库变异的表征

以干旱、半干旱地区荒漠草地不同沙漠化阶段土壤为研究对象,研究不同沙漠化阶段土壤易氧化有机碳与溶解性有机碳含量和分配比例变异规律,分析不同沙漠化阶段土壤碳库指数变化,探讨荒漠草地沙漠化过程中土壤易氧化有机碳与溶解性有机碳对土壤碳库的表征作用。结果表明,随着荒漠草地沙漠化程度的加剧,易氧化有机碳含量表现出一定的波动性,但整体呈下降趋势,溶解性有机碳含量呈线性下降。易氧化有机碳和溶解性有机碳分配比例均在荒漠草地达到最大值,在半固定沙地达到最小值。利用易氧化有机碳含量计算的土壤碳库管理指数随荒漠草地沙漠化程度增加表现出先下降后上升趋势,利用溶解性有机碳含量计算的土壤碳库管理指数呈线性下降趋势。易氧化有机碳、溶解性有机碳含量与土壤有机碳均显著正相关,但溶解性有机碳的相关系数略高于易氧化有机碳。通过比较活度敏感指数和碳库管理指数敏感指数发现,荒漠草地逆向演替至固定沙地过程中,易氧化有机碳的各项敏感指数均高于溶解性有机碳。固定沙地演替至流动沙地过程中,溶解性有机碳的各项敏感指数均高于易氧化有机碳,表明易氧化有机碳能够较好地表征荒漠草地沙漠化前期土壤碳库变化,而荒漠草地沙漠化中期和后期利用溶解性有机碳表征效果更好。     

Improved milk production through PG–PL system by provision of in‐house shelter management in lactating Murrah buffaloes during winter season

Comprehensive information on the role of β‐casein and plasminogen–plasmin (PG–PL) system in milk secretion of Murrah buffaloes during winter season is lacking, although effects of cold stress can be ameliorated to an extent by altering microclimate at farm level. Hence, this study was aimed to determine the changes in productivity along with PG–PL system of milk, plasma hormones and metabolites of buffaloes during winter (December–January) season under two different management systems. Average minimum temperature and wind chill index during this season were 7.02 and 12.74 °C respectively. Buffaloes were divided in two groups of six animals each: control and treatment, where treatment group animals were placed in‐house with floor bedding of paddy straw and the control group animals in loose housing system without straw bedding. Physiological responses were recorded, and milk and blood samples were collected at weekly intervals for six‐week experimental period. Under in‐house management system, buffaloes experienced better comfort by alleviating environmental stress as their physiological responses such as respiration rate and pulse rate were significantly reduced (p < 0.01) as compared to the control, which subsequently resulted higher milk yield by 9.92% (p < 0.05). Analysis of milk samples revealed higher concentration of plasminogen (10.6 vs. 8.05 μg/ml; p < 0.01) and β‐casein (p < 0.05), and lower plasmin level (0.299 vs. 0.321 μg/ml; p < 0.05) in buffaloes under treatment group. It was also found that plasma cortisol, glucose and non‐esterified fatty acids levels were higher (p < 0.01) in control group as compared to the treatment animals by 13.6%, 8.14% and 12.6% respectively. However, milk composition, growth hormone, epinephrine and norepinephrine level in plasma were similar in both the groups. Hence, it may be concluded that provision of in‐house shelter management with floor bedding of paddy straw during winter was effective to minimize environmental stress and improved milk production through manipulation of PG–PL system in buffaloes.     

Effect of gut stress induced by oxidized wheat gluten on the growth performance,gut morphology and oxidative states of broilers

This study was to investigate the effect of oxidized wheat gluten (OG) on growth performance, gut morphology and its oxidative states of broilers. One hundred and eighty‐day‐old male broilers (10 chicks/pen) were randomly allocated into three dietary treatments: control diet (CON), diet with 8% wheat gluten (WG) and diet with 8% OG with six pens/treatment. Body weight (BW) (21 and 35 days) and average daily gain (ADG) (1–21 days and 22–35 days) decreased (p < .05) and feed conversion ratio (FCR) (1–21 days and 22–35 days) increased (p < .05) in OG treatment. Feed intake (FI) decreased (p < .05) in WG and OG treatments during 22–35 days. However, FI was not influenced by dietary treatments during 1–21 days (p > .05). The OG‐fed broilers had a lower faecal pH value (p < .05) and higher faecal moisture content (p < 05) at 14, 21, 28 and 35 days. Villus height, crypt depth and V/C value were not different (p > .05) among treatments at 21 and 35 days. Lipid peroxidation (LPO) (21 and 35 days) and malondialdehyde (MDA) (35 days) content in crop of OG treatment increased (p < .05). Oxidized glutathione (GSSG) (21 days), LPO (21 and 35 days) and MDA (21 and 35 days) content in ileum of OG treatment increased (p < .05). The reduced glutathione/oxidized glutathione (GSH/GSSG) (21 days) and (GSH) (35 days) in ileum of OG treatment decreased (p < .05). The present findings indicate that OG might be a stressor for broiler gut, which could induce oxidative stress both in crop and in ileum, and the diarrhoea as well. The growth performance of broiler was consequently depressed.     

Effect of water restriction on milk yield and quality in Lacaune breed ewes

The effect of water restriction on body weight, body condition score, milk yield, and milk composition and rheological characteristics in intensively reared Lacaune ewes was evaluated. After 7 days of adaptation, the trial lasted 28 days. Thirty lactating ewes (48 ± 5 months of age; mean value ± standard deviation) at the beginning of third lactation month were divided into three groups (n = 10), corresponding to the following water restriction treatment: a group control received no drinking water restriction (W100), and two groups received water to the extent of 80% and 60% of W100 daily consumption (W80 and W60 group respectively). The effects of water restriction were assessed at the beginning of experiment (D0), at D14 and D28. The W60 group resulted in a significant decrease in body weight, body condition score, milk yield and feed consumption of hay due to the experimental treatment; whereas a marked increase in both W60 and W80 groups of milk lactose, urea, sodium, sodium chloride content and titratable acidity was observed. Rheological parameters of milk, rennet coagulation time and curd‐firming time were positively affected by water restriction treatments, with a decrease in both experimental groups of the time required for the formation of a stable and firm curd. Results highlight the importance of water consumption in dairy sheep. The scarce availability of water, significantly affecting ewes milk production, is worthy of particular attention in arid area where water stress‐resistant breeds should be considered. This study underlines that milk yield, being closely linked to the availability of water of the breeding habitat due to its high water content (about 81%), could be reached in area where water is not a limiting factor without reducing the genetic expression of the animals. Less severe water restrictions, such as 20% of daily voluntary water intake, produce no detrimental effect on milk yield.