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21.
SUMMARY Chronic fluoride toxicosis caused lameness, dental lesions and illthrift in an extensive beef cattle herd in northern Australia. Up to 15% of the herd was lame and the disease forced the culling of large numbers of cows. The source of fluoride was fertiliser-grade monoammonium and diammonlum phosphate fed as part of a mineral supplement. Large quantities of mineral supplement were provided to the cattle because lameness was attributed to phosphorus deficiency, which is endemic in the area. Most lameness developed in the late dry season in the post-lactation phase. Severe lameness was caused by fractured pedal bones. 相似文献
22.
KINETICS OF DICHLOBENIL DEGRADATION IN SOIL 总被引:2,自引:0,他引:2
Summary. The rates of degradation of dichlobenil (2,6-dichlorobenzonitrile) in soil were determined at 67 and 267°C. The degradation followed first-order kinetics but at 67°C this occurred after an initial lag period of 10 weeks. The half-lives were 28 weeks (+ 10 weeks lag) at 6.7°C and 19 weeks at 26.7°C. The activation energy for the decomposition was the relatively low value of 3.57 kcal/mole, indicating that the degradation of dichlobenil is not as markedly affected by temperature as that of many other herbicides. The only detectable metabolite was 2,6-dichlorobenzamide, a compound that should have a substantially lower vapour pressure and a higher affinity for surfaces than the parent compound. Cinétique de la dégradation du dichlobénil dans le sol Résumé. Les taux de dégradation du dichlobénil (2,6-dichlorobenzonitrile) dans le sol ont été détermines à 6,7 et 26,7°C. La déSgradation suivit une loi cinétique du premier ordre, mais à 6,7°C ceci se produisit aprés une période initiate de latence de 10 semaines. Les demi-vies furent de 28 semaines (plus 10 semaines de latence) a 6,7°C et 19 semaines à. 26,7°C. L'énergie d'activation pour la décomposition s'établit à la valeur relativement faible de 3,57 kcal/mole; ceci indique que la dégradation du dichlobénil n'est pas aussi profondément affcctée par la température quc celle de beaucoup d'autres herbicides. Le seul métabolite detectable fut le 2,6-dichlorobenzamide, composé qui devrait avoir une pression de vapeur notablement plus faible et une affinité plus grande pour les surfaces que le composé apparenté. Kinetik des Dichlohenil-Abbaus im Boden Zusammenfassung. Es wurde die Abbaugeschwindigkeit von Dichlobenil (2,6-Dichlorbenzonitril) im Boden bei 6,7°C und 26,7°C bestinimt. Der Abbau entsprach einer Reaktion erster Ordnung. Bei 6,7°G setzte der Abbau nach einer lag-Phase von 10 Wochen ein. Die Halbwertzeiten betrugen 28 Wochen (+10 Wochen lag-Phase) bei 6,7°C und 19 Wochen bei 26,7°C. Die Aktivierungsenergie war verhältnisniässig niedrig und betrug 3,57 Kcal/Mol und zeigt, dass der Abbau von Dichlobenil durch Temperatur nicht so stark beeinflusst wird wie bei vielen anderen Herbiziden. Der einzige nachweisbare Metabolit war 2,6-Dichlorbenzamid, der einen wcsentlich nieddgeren Dampfdruck und eine grössere Affinität gegenüber Oberfiächen haben dürfte als die ursprüngliche Verbindung. 相似文献
23.
SONG Lianjie CUI Yingying ZHAO Yiping BAI Dongyi REN Xiujuan TE Rigele DUGARJAVIIN Manglai LI Bei 《中国畜牧兽医》2007,47(9):2751-2758
To study a simple and rapid separation of testis Sertoli cells in Mongolian horses and ensure their activity,the testis tissue of two-year-old Mongolian horses was mechanically isolated under a low temperature environment in this experiment,and 1-3 g of testis tissue was chopped,the free red blood cells and interstitial cells were removed by gravity precipitation method.0.1% collagenase Ⅳ and 0.25% trypsin-EDTA were used for tissue digestion, and cells were cultured in medium containing 10% fetal bovine serum.After inoculation,the purified Sertoli cells were isolated and purified by differential sticking method,and the impurity cells were removed by Tris-HCl infiltration method,and were identified by alkaline phosphatase (AKP) staining,HE staining and Real-time quantitative PCR.The results showed that most of the cells began to adhere to the wall after culture 24 h,and the shape of the cells was oval.After culture 48 h,the cytoplasm increased and the refraction became stronger.After culture 3-4 d,the cytoplasm of the cells expanded into tight junction.At this time,the cells were triangular with obvious nucleoli.After culture 6-7 d,the cells entered the stable phase.Real-time quantitative PCR results showed that the expression of GATA4 and GDNF genes were extremely significantly expressed in cultured cells (P<0.01).AKP staining supported the negative expression in Sertoli cells,indicating that the isolated cultured cells were indeed Sertoli cells.In this experiment,tissue was treated by mechanical separation and two-step enzyme digestion,and testicular support cells were obtained quickly and efficiently,the method of culturing Sertoli cells in Mongolian horses testis in vitro was successfully constructed. 相似文献
24.
苜蓿蓟马抗性与生理活性相关性研究 总被引:3,自引:0,他引:3
1材料与方法1.1试材与试验地概况供试材料为现蕾期的草原2号紫花苜蓿、敖汉苜蓿、阿尔冈金苜蓿及自选抗蓟马新品系紫花苜蓿。试验地设置在呼和浩特内蒙古农业大学科技园区牧草试验站内种植3年的人工草地。该地位于东经111°48’,北纬40°48’,海拔1063m,属于典型大陆性气候,日气温最高和最低分别为36.9℃和-33℃,年均气温5.4℃,≥10℃年积温2915℃,年平均降水量350-400mm,主要集中在7-9月,无霜期135d: 相似文献
25.
蓟马对紫花苜蓿危害的空间分布特征 总被引:2,自引:0,他引:2
昆虫空间分布格局是其种群的一种客观属性,对于同一种群,其格局类型是固有的.蓟马为一种体型较小的昆虫,取食时移动性强,易逃逸,所以用危害特征的空间分布来代替其本身的空间分布更具有稳定性和实用性.采用不同尺度研究探讨蓟马对紫花苜蓿危害的空间分布特征.研究表明在现蕾期危害空间分布为聚集分布,危害斑块尺度是40 cm×30 cm~50 cm×30 cm的椭圆型,长轴方向是东西向.因此在这一物候期选择抗蓟马材料时,取样应该按南北方向,尺度距离大于40~50 cm,更具有代表性,在开花期危害空间分布为均匀分布,但是取样尺度也应大于40~50 cm,更具有代表性,而且在开花期取样要比现蕾期取样更好一些,会减少取样误差. 相似文献
26.
Six sympatric species of 5-million-year-old (late Hemphillian) horses from Florida existed during a time of major global change and extinction in terrestrial ecosystems. Traditionally, these horses were interpreted to have fed on abrasive grasses because of their high-crowned teeth. However, carbon isotopic and tooth microwear data indicate that these horses were not all C4 grazers but also included mixed feeders and C3 browsers. The late Hemphillian Florida sister species of the modern genus Equus was principally a browser, unlike the grazing diet of modern equids. Late Hemphillian horse extinctions in Florida involved two grazing and one browsing species. 相似文献
27.
巴美肉羊INHA和INHBA基因多态性与产羔数关系研究 总被引:1,自引:0,他引:1
为了研究INHA和INHBA这两个基因对巴美肉羊产羔数的影响,采用PCR-SSCP技术检测抑制素α亚基(α-inhibin,INHA)和βA亚基(βA-inhibin,INHBA)基因在巴美肉羊中的单核苷酸多态性。结果发现,引物1,4,6扩增片段有多态性,其余3对引物的扩增片段均不存在多态性。引物1,巴美肉羊有2种基因型AB型和AA型,平均产羔数AB型比AA型多0.17只(P<0.01)。引物4,巴美肉羊存在3种基因型(CC、DD和CD),巴美肉羊平均产羔数DD型比CC型多0.44只(P<0.01)。引物6,巴美肉羊有3种基因型(EE、FF和EF),EE型比EF型平均产羔数多0.21只(P<0.01),结果表明,抑制素α亚基(α-inhibin,INHA)和βA亚基(βA-inhibin,INHBA)基因是影响巴美肉羊产羔数的重要基因。 相似文献
28.
为研究一种简单快速分离蒙古马睾丸支持细胞并保证其活性的基本方法,本试验采集2岁蒙古马睾丸组织于低温环境下进行机械分离,将1~3 g睾丸组织剪碎,采用重力沉淀法去除游离的红细胞和间质细胞;使用0.1%胶原酶Ⅳ和0.25%胰蛋白酶+EDTA逐步进行组织消化,并用含有10%胎牛血清的培养基进行细胞培养;在接种后采用差异贴壁法分离纯化支持细胞,使用Tris-HCl低渗法去除杂质细胞,并采用碱性磷酸酶(AKP)染色、HE染色、实时荧光定量PCR方法进行鉴定。结果显示,支持细胞贴壁性能较强,培养24 h后大多数细胞开始贴壁,细胞形状呈椭圆形;培养48 h后胞质增多,折光性变强;培养3~4 d细胞胞质展开紧密连接,此时细胞呈三角形,有明显的核仁,培养6~7 d细胞生长状态进入稳定期。实时荧光定量PCR结果显示,GATA4和GDNF基因在培养细胞中极显著表达(P<0.01),AKP染色支持细胞呈阴性表达,表明分离培养的细胞确为支持细胞。本试验使用机械分离法与两步酶消化法处理组织,可快速高效地获得睾丸支持细胞,成功构建了蒙古马睾丸支持细胞体外培养方法。 相似文献
29.
以熔喷过程中的气流场为核心,建立熔喷过程的数学物理模型,采用数值模拟的方法进行研究。以Navier-Stocks方程为基础,应用基于同位网格的SIMPLER算法并行化计算气流场的速度分布,将试验测试值与数值模拟进行比较,结果表明:采用的数值模拟方法是有效的,完全可以用于模拟双槽钝头型模具的熔喷过程。 相似文献
30.
The snail Physella virgata virgata, a widely distributed freshwater pulmonate, was observed to change its life-history characteristics in the presence of the crayfish Orconectes virilis in spring-fed Oklahoma streams. These changes were apparently initiated by a water-borne cue released when crayfish fed on conspecific snails. In the presence of the cue, snails exhibited rapid growth rates and little reproduction until they reached a size of about 10 mm after 8 months. In the absence of the cue, snails typically grew to about 4 mm (3.5 months) and then began reproduction. The chemically inducible shift indicates that the life histories of these snails are phenotypically plastic. By increasing the variance associated with size and age of maturity, prey may increase the likelihood of coexisting with seasonal predators. 相似文献