有机农业防治面源污染的对策与建议

该文介绍了中国农业面源污染现状,分析了有机农业防治农业面源污染的重要作用及研究现状,从加大政策扶持和资金支持力度、建立有机农业种植生态补偿机制、拓宽有机食品销售渠道、加强有机认证机构的管理等4个方面对发展有机农业提出了意见和建议。     

Fbxw7β, E3 ubiquitin ligase,negative regulation of primary myoblast differentiation,proliferation and migration

Satellite cells attached to skeletal muscle fibers play a crucial role in skeletal muscle regeneration. During regeneration, the satellite cells proliferate, migrate to the damaged region, and fuse to each other. Although it is important to determine the cellular mechanisms controlling myoblast behavior, their regulators are not well understood. In this study, we evaluated the roles of Fbxw7 in primary myoblasts and determined its potential as a therapeutic target for muscle disease. We originally found that Fbxw7β, one of the E3 ubiquitin ligase Fbxw7 subtypes, negatively regulates differentiation, proliferation and migration of myoblasts and satellite cells on muscle fiber. However, these phenomena were not observed in myoblasts expressing a dominant‐negative, F‐box deleted Fbxw7β, mutant. Our results suggest that myoblast differentiation potential and muscle regeneration can be regulated by Fbxw7β.     

Effect of soy lecithin on total cholesterol content,fatty acid composition and carcass characteristics in the Longissimus dorsi of Hanwoo steers (Korean native cattle)

This study aims to investigate the effect of soy lecithin on the total cholesterol content, the fatty acid composition and carcass characteristics in the Longissimus dorsi in Hanwoo steers. Hanwoo steers (24 head) were fed two diets: Control (CON) (concentrate + alcohol‐fermented feed (AFF)) and soy lecithin treatment (CON + soy lecithin at 0.5% of the AFF). Soy lecithin treatment increased average daily gain, serum concentrations of triglyceride, total cholesterol and high‐density lipoprotein‐cholesterol in the blood. A lower cholesterol concentration was found in the Longissimus dorsi for the soy lecithin diet compared to the CON diet. With respect to the marbling score and quality grade of Longissimus dorsi, soy lecithin supplementation significantly increased the C20:5n3, C22:4 and polyunsaturated fatty acids contents compared to the CON diet. Soy lecithin supplementation would alter the total cholesterol content, polyunsaturated fatty acid profile and meat quality of Longissimus dorsi.     

Search for an index for the taste of Japanese Black cattle beef by panel testing and chemical composition analysis

To search for an index for chemical composition related to superior taste in Japanese Black beef, we conducted panel tests and analyzed the chemical composition of seven beef brands. Thirty‐five sirloin beefs from five heifers were used in this study, sold under seven beef brands graded as more than A4 on the Japanese Meat Grade scale. The chemical composition analyses assessed both raw and roasted meat, the latter of which was roasted under the same conditions as those used for the panel test. Results of the panel test and chemical composition analyses revealed that fatty acid composition, sugar content, adenosine triphosphage (ATP)‐related compounds, amino acid composition and odor composition in the sirloin meat differed among beef brands. Furthermore, the correlations of chemical compositions between roasted and raw meat were significantly high. Sugar content and ATP‐related compounds in roasted meat were significantly correlated with the item ‘overall evaluation’ of the panel test. ATP‐related compounds, such as inosinic acid, carnosine and taurine, in roasted and raw meat were correlated significantly with the item ‘umami intensity’ of the panel test. These results suggest that the composition of these components is important for an index related to the overall evaluation of beef.     

异育银鲫呼肠孤病毒的分离与鉴定

【目的】发现异育银鲫Carassius auratus gibelio新病原,为其病害防控提供理论基础。【方法】从吉林省某养殖场采集异育银鲫出血病疑似病样,对其进行细菌分离及寄生虫观察、鲤疱疹病毒Ⅱ型的PCR检测和人工感染试验,然后用感染滤液接种鲤上皮瘤细胞(EPC),并对其进行电镜观察。对病毒基因组进行SDS-PAGE电泳分析、RT-PCR鉴定及序列测定。【结果】发病异育银鲫无细菌及寄生虫感染,鲤疱疹病毒Ⅱ型的PCR检测无特异性条带,将过滤后的患病鱼组织滤液感染健康异育银鲫,7 d内死亡率高达86.7%。盲传4代后出现明显的细胞病变。负染后电镜下可观察到病毒粒子,直径约70 nm,病毒颗粒近球形,无囊膜结构,初步判断为呼肠孤病毒(暂命名JL-4)。SDS-PAGE结果揭示,JL-4基因组由11条dsRNA组成,呈现水生呼肠孤病毒基因组典型特征。将RT-PCR扩增产物的序列进行聚类分析,结果显示,JL-4与呼肠孤病毒HZ08株S6序列相似性高达99%,证明该分离株为呼肠孤病毒。【结论】从患病异育银鲫中分离到1株呼肠孤病毒。     

盘锦稻区蜘蛛群落的建立与多样性分析

采用吸虫器抽吸法,系统调查了盘锦稻区蜘蛛物种组成及群落的建立过程,并分析了单季稻区蜘蛛群落多样性特点。结果表明,盘锦稻区共采集到10科37种蜘蛛,种类较丰富,其中横纹金蛛Argiope bruennichii、粽管巢蛛Clubiona japonicola和草间钻头蛛Hylyphantes graminicola 3种为优势种蜘蛛。随着水稻插秧,蜘蛛逐渐从非稻田生境向稻田生境迁移,至8月上旬(8月10日前后),种类数达到最大值26种,完成群落建立过程。Shannon-Wiener指数表明,6月初蜘蛛多样性水平最低,8月下旬蜘蛛多样性水平最高,指数最高值为3.0697,而均匀度指数、丰富度指数与其呈正相关,优势度指数与其呈负相关。     

林窗模型中树高直径关系方程分析——以小兴安岭红松林主要树种为例

为了更准确地描述树高与直径的关系,文章综合分析了广泛应用于林窗模型中的四个数学方程,即二次曲线、幂函数方程、理查德方程和单分子方程。通过理论分析和对红松林内主要树种树高和直径关系的非线性回归分析及预测精度检验后,结果表明,理查德方程和单分子方程是林窗模型中描述树高和直径关系的最优模型。     

斜置旋耕三维凸埂研究

斜置旋耕时,由于刀辊的斜置,土垡受到旋耕刀的侧向撕裂而形成一楔状土台,所以应将旋耕沟底不平度的研究扩展到三维空间。本文详细分析了斜置旋耕作业过程中沟底凸埂的成因,建立数学模型确定了斜置旋耕凸埂的立体形状。理论研究和实测结果均表明：斜置旋耕沟底较正置旋耕沟底更为平整。     

Quantitative investigation of Enteromyxum leei (Myxozoa: Myxosporea) infection and relative condition factor in cultured olive flounder Paralichthys olivaceus (Temminck and Schlegel)

Enteromyxum leei has been reported to cause emaciation disease in various fish species. To determine the effect of parasite intensity on cultured olive flounder Paralichthys olivaceus, we investigated the relationship between the relative condition factor (rCF = CF/standard CF × 100) and parasite load with quantitative polymerase chain reaction (qPCR) and the challenge test. A total of 57 cultured olive flounders were obtained from 11 fish farms and divided into five groups based on their rCF. We investigated the parasite intensity in the posterior intestine of the fish. The parasite load was closely matched to severe loss of body weight. In addition, olive flounders were inoculated either orally or anally with intestinal scrapings of infected fish or phosphate‐buffered saline. The fish were reared at natural water temperature and transferred to different tanks, and the water temperature was adjusted to 20°C after 6 weeks of inoculation. When the water temperature was increased to 20°C, the rCF decreased in the experimentally infected group. The results demonstrated that qPCR can be utilized to determine the relative abundance of E. leei in olive flounders and water temperature is an important factor to track the progress of the emaciation disease.     

Effects of Nitrogen Deposition on Invasive and Competitive Abilities of an Alien Plant Ambrosia artemisüfolia

通过温室控制实验,模拟不同的氮沉降量对外来种豚草和本地种黄花蒿、蒙古蒿形态、生物量及其分配以及种间竞争的影响.结果表明:外来种豚草对氮素变化表现出很高的可塑性,而本地种可塑性不高.随氮素的增加,豚草的株高、基茎、总生物量、支持结构生物量比显著增加,根生物量比、根冠比明显降低;本地种除株高、根冠比等少数指标外,多数指标无显著差异.氮沉降有利于外来种豚草在种间竞争中取得优势.豚草和黄花蒿的混栽试验显示,随着氮水平的增加,豚草的竞争力加强,在竞争中取得了优势;豚草和蒙古蒿的混栽试验显示,低氮量下蒙古蒿具有一定的竞争优势,高氮量下竞争优势减弱.全球变化造成氮沉降的增加有利于外来入侵植物的生长与竞争.