基于叶片质外体相关成分和酶活性响应的龙葵耐Cd机理研究

为探讨龙葵(Solanum nigrum L.)耐镉(Cd)机理,采用基质培养法,研究了50 μmol·L^-1 Cd(CdCl₂·2.5H₂O)处理120 d对其生长和叶片细胞壁果胶、木质素含量、多聚半乳糖醛酸酶(PG)、纤维素酶(Cx)、NADH-过氧化物酶(NADH-POD)、愈创木酚过氧化物酶(GPOD)和松柏醇过氧化物酶(CAPX)活性以及质外体汁液中过氧化氢(H₂O₂)含量和GPOD、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)和超氧化物歧化酶(SOD)活性的影响。结果表明,与对照相比,Cd处理显著抑制了龙葵地上和地下部的伸长生长、降低了根的干物质积累(P<0.05),但茎的分枝增多,叶面积、叶绿素含量、净光合速率和胞间CO₂浓度无显著变化(P>0.05);细胞壁结合酶NADH-POD、GPOD和CAPX活性以及果胶含量显著增高(P<0.05),而PG活性显著下降(P<0.05),Cx活性和木质素含量无显著变化(P>0.05);质外体汁液中H₂O₂含量显著增加(P<0.05),GPOD和SOD同工酶谱及活性无显著变化(P>0.05);CAT同工酶谱带增宽,APX同工酶谱带数增加,二者活性均显著升高(P<0.05)。说明50 μmol·L^-1 Cd较长时间处理龙葵植株,其地上部分生长仍处于良好状态,表现出对Cd毒害的耐性,这与Cd处理后叶片细胞壁果胶含量和结合酶GPOD以及质外体汁液中APX、CAT活性升高有关,推测这是龙葵耐Cd的一种机理。     

Effects of organic selenium supplemented diet on growth performance and antioxidant response in Cirrhinus mrigala

The present study was conducted to evaluate the …effect of dietary selenium on growth performance and antioxidant enzymes activity in Cirrhinus mrigala for a period of 45 days. Four numbers of experimental diets were prepared, T_c for Control (0 mg organic selenium/kg of diet), T₁ (2.5 mg organic selenium/kg of diet), T₂ (5.0 mg organic selenium/kg of diet) and T₃ (10 mg organic selenium/kg of diet). The water quality parameters (temperature, DO, pH, conductivity, hardness, ammonia, nitrate and nitrite) were found to be insignificant (p > .05) among all the treatments. Superoxidase dismutase (SOD) was found to be significantly highest in T₂ (6.10 ± 0.07) when compared with the other treatments. Similarly, catalase (CAT) activity in T₁ (13.21 ± 0.13) was significantly (p < .05) different with that of Control, T₂ and T₃. Present study also revealed that 2.5mg organic selenium/kg supplemented diet (T₁) showed highest results in net weight gain (15.55 ± 1.36 g), net weight gain percentage (185.88 ± 8.98%) and SGR (2.35 ± 0.06 g) compared with other experimental diet.     

Study on the adaptability of common carp (Cyprinus carpio) to diets from the perspective of digestion and absorption

As an ecologically sustainable aquaculture mode, the rice‐fish approach has been paid more attention in recent years. In rice paddies, there are plant and animal diet items available to fish, but it is not clear how common carp adapt to different diets. In view of this, common carp (initial weight 492.6 ± 30 g, n = 270) were randomly divided into three groups and fed with earthworms (group A), earthworms + duckweed (group M) and duckweed (group P) respectively. After 8 weeks under these feeding regimes, the intestinal digestive enzymes activities were assayed, and intestinal tissue sections stained with HE and AB‐PAS were used to observe the morphology. The results showed that the activities of trypsin and lipase were highest in group A, followed by group M and group P. Group A had greater intestinal fold height, fold width and fold absorption area than the other groups (p < .05), especially in the foregut. Meanwhile, the total number of mucous cells was largest in group P, followed by the groups M and A. Totally, activities and distributions of digestive enzymes, fold height, fold width, fold absorption area and number and distribution of mucous cells of common carp were affected by the type of diet. Based on these results, it was found that common carp has strong adaptability to diets, and it was speculated that the majority of digestion and absorption of protein was concentrated in the foregut, while for starch and cellulose, it was spread out along the whole intestine.     

黄条鰤仔稚幼鱼消化酶活性变化研究

为了解黄条鰤(Seriola aureovittata)早期发育阶段的消化生理特性，测定了黄条鰤胚胎、仔稚幼鱼阶段脂肪酶、淀粉酶、胰蛋白酶和碱性磷酸酶活性变化。结果显示，在黄条鰤仔鱼出膜前胚胎阶段，即能检测到脂肪酶、淀粉酶和碱性磷酸酶活性；初孵仔鱼体内(1 d)初次检测出胰蛋白酶的活性。脂肪酶和碱性磷酸酶比活力在仔鱼孵化后迅速增强(P<0.05)，在4 d开口时，2种酶比活力达最高值；淀粉酶比活力在7 d时达最大值；胰蛋白酶比活力在仔鱼阶段缓慢上升，15 d时比活力最大。稚鱼阶段内脏团中脂肪酶、碱性磷酸酶和胰蛋白酶活性基本维持稳定，幼鱼阶段内脏团脂肪酶、碱性磷酸酶和胰蛋白酶活性都呈现上升趋势；稚鱼和幼鱼阶段内脏团中淀粉酶活性下降并基本稳定于较低水平。研究表明，黄条鰤仔稚幼鱼发育过程中，各种消化酶活性变化明显，且与其发育阶段和食性密切相关。在尚未摄食饵料的早期仔鱼体内已存在消化酶，认为其是母源传递而来，不是由外源性饵料所致；幼鱼阶段内脏团脂肪酶、碱性磷酸酶和胰蛋白酶比活力明显提高，这反映出随苗种生长发育，其肠道结构和消化机能逐渐完善，并且对脂肪、蛋白质的需求逐渐增强。     

不同罗非鱼品系感染无乳链球菌后对血液和肝胰腺生化指标的影响

为探究无乳链球菌(Streptococcus agalactiae)感染后对罗非鱼的血液和肝胰腺生化指标的影响，本研究以吉富罗非鱼(Oreochromis niloticus)抗病选育系F5代、奥尼罗非鱼(Oreochromis aureus × O. niloticus)、吉富罗非鱼“百桂”品系为对象，通过人工腹腔注射感染无乳链球菌，检测感染后不同时期肝胰腺和血液中的酸性磷酸酶(ACP)、碱性磷酸酶(AKP)、过氧化氢酶(CAT)、超氧化物歧化酶(SOD)、总抗氧化能力(T-AOC)和溶菌酶(LZM)活性的变化。结果显示，奥尼罗非鱼、吉富罗非鱼抗病选育系F5代和吉富罗非鱼“百桂”品系的平均死亡率分别为55.4%、60.5%和78.6%，表明奥尼罗非鱼抗感染能力最强；3个品系感染无乳链球菌后，肝胰腺组织中的ACP、AKP、SOD和T-AOC酶活力均呈先升高后下降的趋势，其中，在感染后24 h，奥尼罗非鱼的AKP和CAT酶活力显著高于吉富罗非鱼抗病选育系F5代和吉富罗非鱼“百桂”品系；而感染后24 h，血清中ACP、AKP、LZM、CAT和T-AOC酶均显著升高，而SOD酶则下降，其中，奥尼罗非鱼的ACP、AKP、CAT和T-AOC酶活性明显高于吉富罗非鱼抗病选育系F5代和吉富罗非鱼”百桂”品系。综合比较6种酶在感染后不同时期的活性变化及3个品系的感染存活率，筛选出AKP和CAT作为评估罗非鱼抗无乳链球菌感染能力强弱的指标。     

大黄鱼消化道菌群结构、消化酶和非特异性免疫酶活力分析

为研究大黄鱼(Larimichthys crocea)消化道的菌群结构、消化酶和非特异性免疫酶活力特征，本研究采用高通量测序技术系统分析大黄鱼胃、幽门盲囊和肠道中菌群组成及分布，并对比研究工厂化养殖和网箱养殖模式下的消化道菌群；同时，结合生化分析方法解析2种模式下消化道消化酶和非特异性免疫酶活力特征。结果显示，2种养殖模式下，菌群多样性随消化道延伸呈下降趋势；乳杆菌科(Lactobacillaceae(f))、Fructobacillus、黄杆菌属(Flavobacterium)等代表的菌属为共有优势菌群。其中，拟杆菌属(Bacteroides)和Anaerostipes等的丰度随消化道延伸呈下降趋势，而乳杆菌科、E01_9C_26_marine_group(o)所代表的菌属及黄杆菌属等则相反；普氏菌属(Prevotella_9)、乳杆菌科代表的菌属为2种模式养殖大黄鱼的主要差异菌属。工厂化养殖条件下，幽门盲囊和肠道中的菌群组成及其参与营养和免疫相关代谢通路的基因数目差异不显著(P>0.05)，但与胃部的菌群组成和相关代谢通路基因数目存在明显差异；而网箱养殖大黄鱼胃部与幽门盲囊和肠道的菌群结构及相关代谢通路基因数目差异相对较小。2种养殖模式下的大黄鱼消化道菌群与饲料菌群相近。另外，胃和幽门盲囊也具有非特异性免疫酶活性，说明，整个消化道还具有一定的化学免疫屏障作用。本研究结果将为大黄鱼健康养殖提供基础参考，并为消化道菌群生理功能探讨提供理论依据。     

The effects of exogenous xylanase supplementation on the in vivo generation of xylooligosaccharides and monosaccharides in broilers fed a wheat-based diet

ABSTRACT

1. This study quantified xylanase-induced changes in soluble monosaccharides, xylooligosaccharides (XOS) and volatile fatty acid (VFA) contents of the different sections of the gastrointestinal tract (GIT) and whether these were related to altered bird performance.

2. An in vitro digestion of the wheat-based diet was carried out with the xylanase (Econase XT at 16,000BXU/kg diet) to compare the in vitro and in vivo generation of these XOS and monosaccharides. For the in vivo study, 80 male Ross 508 b roiler chicks were split into two groups fed a wheat-based diet with or without Econase XT (16,000BXU/kg diet) for 21 days.

3. There were no effects of Econase XT inclusion on growth performance characteristics, likely a result of the high-quality wheat diet, the corresponding high performance of the control group (FCR average of 1.45 in controls) and the relatively young age of the birds (from four to 26 days of age).

4. Econase XT supplementation increased the xylotetraose (X₄) content in the colon (P = 0.046, enzyme x GIT section interaction) and the xylose contents in the colon and caeca (P < 0.001, enzyme x GIT section interaction).

5. The trend for increased acetate production in the caeca of Econase XT treated birds (P = 0.062) suggested that the XOS generated were subsequently fermented in the caeca, potentially impacting upon the types of microbiota present.

6. The present study suggested that wheat arabinoxylan degradation was enhanced by xylanase supplementation, which may have increased the production of beneficial volatile fatty acids (VFA) in the caeca, and thereby potentially modulated the caecal microbiome, but without affecting bird performance at this early age.     

草地灌丛化土壤碳氮地球化学循环

灌丛化(shrub encroachment)是全球陆地生态系统重要的生态现象之一,是影响草地碳库的重要过程。灌丛化由全球气候变化、降雨、火烧和生物活动等多因素共同作用形成,对区域环境、气候、土壤性质和碳循环影响显著。目前灌丛化对生态系统的影响仍存在分歧,表现在不同气候和降雨梯度下灌丛化后土壤有机碳/氮储量、养分循环和土壤温室气体排放等差异。本文总结和归纳了灌丛化形成与控制因素、灌丛化对团聚体稳定性、酶活性和土壤碳、氮循环的影响。灌丛化改变了土壤团聚体稳定性和酶活性,进而影响土壤呼吸以及土壤生源物质的存储、分解和循环,这将显著影响区域乃至全球气候变化。因此分析提出,今后应进一步加强对灌丛化形成过程长期的定位观察研究,以便了解灌丛化的可控因素,并加强对灌丛化后土壤有机碳库、土壤团聚体稳定性变化对碳氮循环进程和全球气候变化的影响研究。     

Biochemical defense responses of black pepper (Piper nigrum L.) lines to Phytophthora capsici

A study on biochemical factors involved in black pepper defense response against Phytophthora capsici, was carried out in P. capsici susceptible (Sreekara) and resistant (04-P24, shows root resistance to the pathogen) black pepper lines. Seven important factors – change in membrane conductance, total phenols, orthodihydroxy (OD) phenols, lignin and defense related enzymes (peroxidase, β-1,3 glucanase and β-1,4 glucanase) – were studied under uninoculated and pathogen (P. capsici, isolate 06-04) inoculated condition to know the preformed and induced responses. The pathogen was inoculated (soil inoculation) and plants were observed for changes, at 24 h intervals for 10 days. On 8th day after inoculation symptoms started appearing on Sreekara and increased the severity till 10th day. Both root and stem samples were subjected for biochemical analysis. Of the factors analyzed, it was found that membrane conductance, OD phenol, lignin and peroxidase activity play significant role in root resistance to P. capsici in 04-P24. Light microscopy of the portion of root – where pathogen found attached – was also done.