高脂日粮对小鼠消化系统自由基水平与物质消化、吸收的影响

选取6周龄雄性昆明种小鼠40只,按体质量随机分成4组:即对照组(正常日粮),高脂日粮组(粗脂肪含量18%),LA组(高脂日粮+0.05%LA和高脂日粮+0.1%LA).小鼠预饲1周后正式饲喂,饲喂5周后进行代谢试验.6周后测定小鼠消化系统自由基水平和肠道黏膜脂肪酶、蛋白酶和淀粉酶活性.结果表明,长期饲喂高脂日粮可显著提高小鼠消化系统自由基水平(P<0.05),降低肠道淀粉酶和蛋白酶活性(P<0.05),但肠道脂肪酶活性显著提高(P<0.05);小鼠对粗脂肪和粗蛋白消化率降低(P<0.05),蛋白沉积率降低(P<0.05).添加0.05%LA后,能显著降低高脂饲喂小鼠消化系统自由基水平(P<0.05),提高小鼠对粗脂肪、粗蛋白消化率(P<0.05),和蛋白沉积率(P<0.05);添加0.1%LA可使小鼠全血及系统自由基水平恢复到接近正常水平.由此得出:高脂摄入,增加小鼠消化系统自由基生成,降低消化酶活性、降低机体对营养物质的消化吸收.适宜的LA添加可有效清除小鼠消化系统自由基,提高消化酶活性,提高营养物质的利用率,缓解营养性氧化应激.     

Effects of dietary protein and growth hormone-releasing peptide (GHRP-2) on plasma IGF-1 and IGFBPs in Holstein steers

This study was conduct to determine the influence of dietary protein on the response of plasma insulin-like growth factor-1 (IGF-1) and insulin-like growth factor binding proteins (IGFBPs) to exogenous growth hormone releasing peptide-2 (GHRP-2 or KP 102) in Holstein steers. Eight 16-month-old Holstein steers were grouped by liveweight to two feeding treatments; high protein (HP; CP 1.38 kg/day and TDN 4.5 kg/day DM intake, n=4) or low protein (LP; CP 0.66 kg/day and TDN 4.42 kg/day DM intake, n=4). The experiment was a single reverse design whereby each group was injected twice daily with GHRP-2 (12.5 microg/kg body weight (BW)/day) or saline solution into the jugular vein for a 6-day period. Plasma IGF-1 in the HP group were higher than in the LP group (P<0.05), but plasma 34 kDa IGFBP-2 was lower in the HP than the LP group (P<0.05). The amplitude of the maximum growth hormone (GH) peaks responding to GHRP-2 injection were higher at day 1 than at day 6 of saline or GHRP-2 treatment in both LP and HP steers (P<0.05). The area under the GH response curve for 180 min after the GHRP-2 injection was not significantly different between the LP and the HP groups at days 1 and 6. A response in plasma IGF-1 concentration to GHRP-2 treatment in the HP group was observed at day 1 (198.9+/-18.1 ng/ml), day 2 (195.2+/-21.1 ng/ml) and day 6 (201.3+/-14.8 ng/ml) (P<0.05). No increase in plasma IGF-1 was observed from GHRP-2 administration in the LP group. Although the response of plasma IGF-1 concentration to GHRP-2 administration was increased in the HP group (P<0.05), there was no apparent effect of GHRP-2 treatment on plasma 38-43 kDa IGFBP-3 and 34 kDa IGFBP-2 at days 2 and 6 of treatment. In conclusion, it is proposed that the 34 kDa IGFBP-2 is sensitive to dietary protein level and may play an important role in the regulation of circulating IGF-1 in ruminant. In addition, increased plasma IGF-1 concentration observed in the HP group in response to the GHRP-2 treatment did not appear to affect plasma IGFBPs.     

西南“旱三熟”区不同作物和秸秆覆盖对土壤团聚体及固碳潜力的影响

为了探讨西南"旱三熟"(小麦/玉米/大豆)套作种植模式下农田土壤团聚体的分布特征及有机碳含量变化情况,进而估算该模式下的土壤固碳潜力,在重庆北碚西南大学试验农场对传统耕作(traditional tillage,T)和传统耕作+秸秆覆盖(traditional tillage+straw mulching,TS)2种处理下的土壤团聚体进行筛分和测定。结果表明,3种作物种植下的2mm粒径与2~0.25mm粒径团聚体含量此消彼长,存在显著的负相关关系(r=-0.985,P0.05)。土壤团聚体结构对不同作物的响应不同,水稳性大团聚体(0.25mm粒径)含量在小麦和大豆种植后高达90%左右,玉米种植后约为80%,说明种植玉米有利于土壤水稳性微团聚体的形成。2~0.25mm粒径团聚体的有机碳含量最高,而水稳性微团聚体的两个粒径团聚体有机碳含量相差不大,有机碳含量在团聚体中的分布规律不受种植作物和耕作方式的影响。秸秆覆盖显著提高了0~5cm和5~10cm土层的本土及各个粒径中的有机碳含量,且5~10cm土层团聚体有机碳受秸秆覆盖的影响较大。通过估算固碳潜力发现,玉米条带的土壤固碳潜力显著大于小麦-大豆条带,在耕作处理保持一致的情况下,土壤团聚体有机碳含量对农作物的响应不同。因此,在西南"旱三熟"地区,农田土壤团聚体分布特征和不同粒径有机碳含量受到耕作措施和种植作物的双重影响,土壤固碳潜力主要由水稳性大团聚体的固碳能力决定,水稳性大团聚体更易受到耕作措施和种植作物的影响,在实践中通过秸秆还田提高土壤固碳外,合理安排农作物也有助于提高土壤的固碳能力。     

4种高原乡土禾草的抗旱生理比较

采用盆栽法对梭罗草（Roegneria thoroldiana）、草地早熟禾（Poa pratensis）、垂穗披碱草（Elymus nutans）和中华羊茅（Festuca sinensis）4种高原乡土禾本科牧草幼苗的抗旱性进行了比较。结果表明,一定程度的干旱胁迫后,4种禾草的游离脯氨酸含量、可溶性蛋白含量、可溶性糖含量、过氧化氢酶活性、过氧化物酶活性等均有所增加,且叶绿素分解、细胞膜透性增大、电解质外渗率增加,牧草组织细胞受到伤害。不同牧草在干旱胁迫下生理生化指标的变化不同,综合各项指标,运用隶属函数分析表明,4种禾草抗旱性强弱的排序为梭罗草>草地早熟禾>垂穗披碱草>中华羊茅。     

Comparison of macrophage scavenger receptor-A knockout mice with wild type ones in the immune response against repeated infestation with Haemaphysalis longicornis

Using macrophage scavenger receptor-A knockout (SRKO) mice, we examined the role of macrophage class A scavenger receptors (MRS-A) on the immune response and acquisition of host resistance against repeated infestation with Haemaphysalis longicornis. Except for one batch of nymphs that infested one of the SRKO (SR-/-) mice and showed no appreciable reduction in body weight, all the other groups of nymphs manifested significant decrease in body weight. Both SR-/- and wild type (SR+/+) mice showed a sustained increase in anti-tick antibody titers, but SR+/+ mice showed significantly higher titers. The IFN-gamma assayed in SR-/- mouse immune sera was substantially less compared with that in SR+/+ mice. Immune sera from SR-/- and SR+/+ mice recognized the 51 and 44 kDa, and 44 kDa proteins, respectively, of the salivary gland antigen. The difference in the level of anti-tick resistance manifested by both groups of mice may be influenced by less efficient trapping and processing of tick antigens by macrophages in mice lacking for the macrophage scavenger receptors, and consequently affected the cascade of Th1 and Th2 responses. We have thus obtained valuable data that strongly infer the role of MSR-A in enhancing host defense against repeated infestation with H. longicornis.     

草坪在生态城市建设中的作用及其应用

论述了草坪在城市生态系统中的生态效应是目前我国在应用草坪提高城市生态质量方面存在的问题，通过对城市生态系统特殊性的分析，提出了草坪系统规划的目的和原则，力求把城市建设成为生态协调、可持续利用和良性循环的人居环境。     

关于农业工程科技发展与创新的思考

结合中国农业发展现状和世界农业发展趋势,阐述了世界农业科技革命的基本特点,分析了农业工程技术创新对推动农业科技革命的重要作用,论述了发展与创新的重点以及推进措施。     

实施GMP后我国兽药产业的竞争态势和应对策略

兽药产业实施GMP以后,根据波特五力模型分析,我国兽药企业竞争竞争态势会发生如下趋势:销售商和原材料供应商将成为兽药企业争夺的焦点。兽药产业的潜在进入者和替代产品对兽药企业威胁都不大,兽药企业面对的经营压力主要来自于业内同类企业和国外兽药企业的竞争。面对竞争态势的变化,兽药企业的应对策略主要是加强与原料药企业的合作,不断完善产品营销网络,实施专业化规模生产。     

棉花体细胞培养再生不育株的性状及细胞学研究

研究了以陆地棉（Ｃｈｉｒｓｕｔｕｍ）晋棉７号、冀合３２１、冀棉７１３、珂字棉３２１、珂字棉２０１等品种为外植体的体细胞培养获得再生突变不育株的形态性状及减数分裂过程中染色体的行为。与再生可育株相比，不育株的株型、分枝、叶、花各器官均较小。花柱、柱头、花丝、花药小而呈萎缩干瘪状，花药不开裂。减数分裂不正常，染色体普遍丢失减少，不能正常配对，出现很多单价体和染色体桥。产生二分体、三分体和多分体，也有正常的四分体。雌配子体和雌配子发育也不正常，胚囊结构不完整，反足细胞迟迟解体，表现雌雄不育。     

GmFW1 expression decreased in GmSymRK knockdown transgenic soybean roots

SymRK and GmFWL1 both play important roles in nodulation. However, during symbiotic development, the details of Nod factor signaling association with the regulation of cell division in nodules are unknown. SymRK, the immediately downstream component of these Nod factor receptors, is central to the Nod factor signaling cascade. In this study, specified RNAi plasmid of GmSymRK was constructed and transformed into soybean roots by agrobacterium rhizogenes-mediated hairy root transformation. We found that the nodule number decreased substantially in GmSymRK knockdown soybean transgenic roots. Further to study the relationship between GmFWL1 and Nod factor signaling, we analyzed the GmFWL1 expression levels in the GmSymRK RNAi soybean transgenic roots and found that rhizobia inoculation led to substantially reduced GmFWL1 expression in GmSymRK RNAi soybean transgenic roots. Our studies showed that the regulation of cell division was affected by Nod factor signaling during nodule development in soybean, which provides important information toward understanding the functions of GmSymRK and GmFWL1 in symbiotic signaling and nodule development.