大气CO2浓度升高和氮肥互作对玉米花后功能叶碳氮同化物的影响

在常规大气CO2浓度（aCO2，400±15μmol·mol−1）和高CO2浓度（eCO2，550±20μmol·mol−1）下分别设置无氮（ZN）和施氮（CN，180kg N·hm−2）2个氮水平的交互处理，以夏玉米品种郑单958为供试材料开展田间试验，测定花后功能叶碳同化物（可溶性糖和淀粉、总碳）动态和氮吸收及同化物组分（硝态氮、游离氨基酸、可溶性蛋白、非溶性氮化合物细胞壁氮素和类囊体氮素、总氮）动态以及碳氮比动态的变化及玉米产量，以探究CO2浓度升高和氮肥交互作用下，以玉米为代表的C4作物花后功能叶不同组分碳氮同化物质量分数及动态和产量的变化，以期为全球气候变化下玉米生理过程的变化提供理论支撑，同时为玉米作物模型调参提供实证数据。结果表明：（1）本试验条件下，大气CO2浓度升高对夏玉米生物量及产量的作用不显著。（2）eCO2下夏玉米花后功能叶主要碳同化产物（可溶性糖和淀粉）和总碳的质量分数显著（P＜0.05）增加，功能叶中氮同化物中简单组分（硝态氮、游离氨基酸及可溶性蛋白）质量分数和碳氮比、地上部生物量、产量也有一定增加，但未达显著水平；而氮同化物中的结构氮组分（如细胞壁氮和类囊体氮）质量分数显著降低，总氮也有一定降低趋势，显示出后期结构氮组分合成有一定不足。（3）氮肥施用显著增加了花后功能叶碳同化物（如可溶性糖和大部分时期淀粉）及各种氮同化物的质量分数和生物量及产量，对总碳的增加作用不显著。（4）eCO2下合理施用氮肥，会使地上部生物量、产量、功能叶中简单碳同化物可溶性糖、简单氮同化物指标（硝态氮、游离氨基酸和可溶性蛋白）和总碳质量分数达到较优。因此，在未来大气CO2浓度升高为特征之一的气候变化背景下，氮素合成的生理调控管理对促进碳氮代谢及玉米高产优质有积极作用。     

Dietary Supplementation of Astaxanthin Improved the Growth Performance,Antioxidant Ability and Immune Response of Juvenile Largemouth Bass (Micropterus salmoides) Fed High-Fat Diet

High-fat diet (HFD) usually induces oxidative stress and astaxanthin is regarded as an excellent anti-oxidant. An 8-week feeding trial was conducted to investigate the effects of dietary astaxanthin supplementation on growth performance, lipid metabolism, antioxidant ability, and immune response of juvenile largemouth bass (Micropterus salmoides) fed HFD. Four diets were formulated: the control diet (10.87% lipid, C), high-fat diet (18.08% lipid, HF), and HF diet supplemented with 75 and 150 mg kg⁻¹ astaxanthin (HFA1 and HFA2, respectively). Dietary supplementation of astaxanthin improved the growth of fish fed HFD, also decreased hepatosomatic index and intraperitoneal fat ratio of fish fed HFD, while having no effect on body fat. Malondialdehyde content and superoxide dismutase activity were increased in fish fed HFD, astaxanthin supplementation in HFD decreased the oxidative stress of fish. The supplementation of astaxanthin in HFD also reduced the mRNA levels of Caspase 3, Caspase 9, BAD, and IL15. These results suggested that dietary astaxanthin supplementation in HFD improved the growth performance, antioxidant ability and immune response of largemouth bass.     

Effects of long‐term elevation of air temperature on sucrose metabolism in cotton leaves at different positions

Global warming could possibly increase the air temperature by 1.8–4.0°C in the coming decade. To forecast the effects of long‐term elevation of air temperature on sucrose synthesis in cotton leaves at different positions, field experiments with the treatments of ambient temperature (control) and elevated temperature (2–3°C) across cotton's boll forming stage were conducted in 2011 and 2012. Results showed that sucrose content in the fourth main‐stem leaves from the terminal (FMLT) during 10–17 days after treatment (DAT) and in the leaves subtending the cotton boll (LSCB) during 17–45 days post‐anthesis (DPA) was lower in the increased temperature treatment than control treatment, but starch content was higher, resulting in higher specific leaf weight (SLW). Lower sucrose content might be attributed to low ribulose‐1,5‐bisphosphate carboxylase‐oxygenase (Rubisco) and cytosolic fructose‐1,6‐bisphosphatase (cy‐FBPase) activities under elevated temperature for all tested leaves. Comparison of different fruiting branch (FB) positions, sucrose transformation rate just decreased in LSCB growing on FB_2–3 and FB_6–7. Compared with FB_10–11, the leaves at FB_2–3 and FB_6–7 were more sensitive to the increased temperature, showing as that the changing amplitudes of SLW, sucrose content, starch content, initial Rubisco activity and cy‐FBPase activity were greater. Regarding different types of cotton leaves, the effects of elevated temperature on sucrose content, starch content and initial Rubisco activity in FMLT were obvious at the early stage (10–17 DAT), but were not obvious at the late stage. However, the effects were consistent in LSCB from 17 to 45 DPA. In addition, long‐term elevated temperature had smaller impacts on above indices in FMLT than LSCB. Sucrose phosphate synthase (SPS) and sucrose synthase (SuSy) activities were decreased by elevated temperature in FMLT at the early stage, but were increased in LSCB, suggesting that SPS and SuSy were the key enzymes between FMLT and LSCB in response to elevated temperature.     

瘤胃异常代谢产物脂多糖对奶牛血浆中代谢产物和激素的影响及其机制

当奶牛饲粮中精饲料水平提高时,瘤胃液pH下降,奶牛常会发生亚急性瘤胃酸中毒(SARA),瘤胃内产生大量异常代谢产物,其中主要是细菌内毒素脂多糖(LPS).在SARA时期,外周血液中的LPS浓度升高,可导致奶牛发生一系列免疫应答,奶牛代谢也发生相应的变化.血浆葡萄糖、非酯化脂肪酸浓度升高,血浆氨基酸、β-羟丁酸、胆固醇和矿物质的浓度发生变化,血浆中的各种激素水平也会发生变化.这些代谢变化进而影响奶牛产奶量、乳脂和乳蛋白含量.本文对LPS对奶牛血浆代谢产物和激素水平的影响进行综述,并就其机制进行探讨.     

日粮能量水平对塞北乌骨鸡生产性能及营养物质代谢的影响

为探索塞北乌骨鸡产蛋期日粮适宜能量水平，选取体重、产蛋率基本一致的产蛋鸡150只，随机分为5组，每组3个重复，每个重复10只鸡，分别饲喂不同能量水平（10.38、10.96、11.50、12.04、12.49 MJ/kg）的日粮，测定其生产性能和营养物质代谢相关指标。结果表明：日粮能量水平对塞北乌骨鸡产蛋性能有显著影响（P＜0.05），日粮代谢能水平为12.04 MJ/kg时，生产性能最高，氮表观代谢率和能量表观代谢率也最高，分别为77.77%和81.69%，显著高于其他各组（P＜0.05）。由此可见，塞北乌骨鸡产蛋期日粮能量水平以12.04 MJ/kg为宜。     

维生素D代谢物调节钙代谢的机理及其应用

维生素D代谢物可调节钙离子吸收,影响动物骨骼的形成与构造。本文旨在简要介绍维生素D的代谢途径、生理功能及维生素D代谢物调节钙离子吸收的分子机理,并总结维生素D代谢物在畜禽生产中的应用。     

隐丹参酮在猪体内外的代谢转化与抗菌活性

试验猪经口服及静脉给予抗菌活性成分隐丹参酮后，采用溶剂萃取，ＴＬＣ反复分离、纯化，并用ＵＶ、ＩＲ及１ＨＮＭＲ鉴定。隐丹参酮在猪体内可代谢转化为丹参酮ⅡＡ。体外全血及肝匀浆温孵试验结果表明，隐丹参酮在体外与全血及肝匀浆温孵条件下，仍可被转化为丹参酮ⅡＡ。体外抑菌试验显示，代谢产物丹参酮ⅡＡ仍然具有抗菌活性，但与原药比较存在差异。     

共轭亚油酸影响边鸡胸肌脂类代谢的相关差异基因的筛选

旨在通过转录组测序技术筛选出共轭亚油酸(conjugated linoleic acids,CLA)影响边鸡胸肌脂类代谢的相关基因,为日粮中CLA调控边鸡脂类代谢的作用机制提供理论依据。本试验选取90日龄健康边鸡180只,随机分为5组,每组3个重复,每组日粮中分别添加不同比例的CLA 0%(对照组)、0.5%、1.0%、1.5%和2.0%,预饲期1周,正饲期6周。饲养试验结束后采集胸肌组织进行转录组测序,使用DESeq2软件对测序数据进行差异表达分析,对差异表达基因进行GO功能和KEGG通路富集分析,筛选出与胸肌脂类代谢相关的差异表达基因,利用qPCR对差异表达基因进行验证。通过转录组测序数据分析,共筛选出1 229个差异表达基因,其中594个基因上调,635个基因下调。随机选取9个差异表达基因进行qPCR验证,其相对表达量变化趋势与测序结果一致。GO功能分析发现,差异表达基因主要集中在生物学过程中的细胞过程、单一生物过程、生物调节和代谢过程。KEGG通路富集分析发现,各试验组中差异表达基因显著富集在不同的信号通路中,主要富集在ECM-受体相互作用、黏着斑、吞噬体、细胞凋亡、肌动蛋白细胞骨架调节和细胞因子-细胞因子受体相互作用等通路中。通过GO和KEGG功能注释分析,共筛选出MCAT、APOA1、PTGDS、ALDH3A2、PLTP、FABP3、FOXO1、UCP3和FABP4等18个主要的参与脂类代谢相关的差异表达基因,可能在调控边鸡胸肌脂类代谢中发挥重要的作用。本研究通过转录组测序筛选出CLA影响边鸡胸肌脂类代谢过程中的主要调控基因,发现了日粮中CLA影响差异表达基因作用的主要生物学过程和信号通路,为今后研究CLA影响边鸡胸肌脂类代谢的分子作用机制奠定了基础。     

微生物-肠-肌轴调节骨骼肌代谢和功能的研究进展

骨骼肌的质量不仅影响着人或动物机体的运动能力和健康状态,还影响着畜禽的肌肉产量和品质。随着对微生物功能的深度挖掘,肠-脑轴、肠-肝轴、肠-脂轴等由微生物及其代谢产物介导的信号途径均被证实参与了机体的能量代谢。近年来,微生物-肠道-骨骼肌轴也被证实,因此通过调控肠道菌群或其代谢产物进而调节机体骨骼肌代谢为改善肌肉产量和品质提供了新的思路。本文主要综述了肠道微生物及其关键代谢产物在骨骼肌功能和糖脂代谢等方面的潜在作用和机制,并简要总结了菌群介导的调控骨骼肌功能的潜在手段,为畜禽养殖中改善肉质提供了一定的参考和新思路。