土传花叶病毒外壳蛋白基因导入小麦的研究

 利用基因枪技术 ,将小麦土传花叶病毒外壳蛋白基因CWMV CP1和筛选基因bar导入扬麦 15 8,获得14 5株抗Bialaphos再生植株 ;PCR Southern分析 ,其中 2 1株为阳性植株 ,转化率达到 0 .99% ;T1代植株的PCR Southern、单酶切和双酶切Southern杂交 ,证明外源抗性基因已经完整地整合到小麦基因组中 ;T1代植株分离比CP1+ ∶CP1-为 1∶1.3,偏离孟德尔分离定律 ;T2 代植株总RNA ,RT PCR的试验结果表明CWMV CP1在转录水平上得到了表达     

Simulating forest cover change in the northeastern U.S.: decreasing forest area and increasing fragmentation

Landscape Ecology - Understanding how the Northern Forest landscape has changed and is likely to change, both in terms of forest extent and forest configuration, has important implications for...     

Concentrations of bioactive and immunoactive luteinizing hormone in bovine anterior pituitary tissue

Tissue concentrations of LH as determined by radioimmunoassay (RIA) may not accurately measure actual changes that could occur in biological activity of the hormone. To examine this possibility, pituitary homogenates from 135 beef cows in various physiological states were analyzed for content of LH by both RIA and an in vitro bioassay. The ratio of biological/immunological active concentrations of LH remained constant (.52 +/- .02) even though tissue concentrations of immunoactive LH differed among groups. Tissue concentrations of bioactive LH were linearly related to, and highly correlated with (P less than .001), tissue concentrations of immunoactive LH. These data indicate that only a fraction of the immunoactive LH in the bovine pituitary is biologically active. However, this fraction does not vary with the reproductive status or plane of nutrition.     

Ranch-management factors associated with antibody seropositivity for Neospora caninum in consignments of beef calves in Texas, USA

A study was conducted with a 1998 retained-ownership population of Texas (USA) beef calves to determine the ranch-management practices associated with calf seroprevalence to Neospora caninum. Management practices of 76 Texas ranches that consigned 760 calves to a retained-ownership feedlot program were reviewed from a mailed questionnaire. Ninety-nine of 760 (13%; 95% CI, 9.4%, 17.7%) calves were positive to N. caninum and 59% of the ranches consigned at least one positive calf. In the logistic multiple-regression model which controlled for overdispersion, increased odds of calf-level seropositivity was associated with seasonal calving patterns, with stocking>1cow/calfunit/2.2ha, using a round-bale feeder, allowing wildlife access to the weaning supplement, and self-reared replacement heifers. However, decreased odds of seropositivity was associated with using a cattle-working dog and with using a self-contained cattle feeder. There was substantial overdispersion due to ranch.     

Comparison of fractional excretion and 24-hour urinary excretion of sodium and potassium in clinically normal cats and cats with induced chronic renal failure.

The influence of induced chronic renal failure on 24-hour urinary excretion and fractional excretion of sodium and potassium was studied in cats. Induction of chronic renal failure significantly increased fractional excretion of potassium (P less than 0.0001) and sodium (P less than 0.05); however, 24-hour urinary excretion of sodium and potassium decreased slightly following induction of chronic renal failure. Fractional excretion and 24-hour urinary excretion of sodium and potassium were compared by linear regression in clinically normal cats, cats with chronic renal failure, and clinically normal and affected cats combined. In clinically normal cats, linear regression revealed only moderate correlation between fractional excretion and 24-hour urinary excretion for sodium and potassium. Linear regression of these same relationships in cats with chronic renal failure, and in clinically normal cats and cats with chronic renal failure combined, indicated low correlation. Fractional excretions of sodium and potassium were not reliable indicators of 24-hour urinary excretion of these electrolytes in cats with chronic renal failure or unknown glomerular filtration rate. Fractional excretion of potassium and sodium correlated only moderately with 24-hour urinary excretion in clinically normal cats.     

Comparative approach to health maintenance: how will it work?

A prototype for the implementation of a comprehensive health maintenance program is described in which the expertise of veterinary medicine is brought to bear on preventive medicine and on special generic environmental disease factors as they impact on human health. For the sake of organization and the ease of presentation, certain specific activities have been divided into two overlapping categories: environmental health and health education. The implementation of a comprehensive health care delivery system will become a reality only when the full array of health resources is matched with health needs. It cannot be overemphasized that the delivery of health care services is not exclusively within the purview of any one profession; rather, interdependence and sharing of responsibilities and activities in a team approach are characteristics of the human health system.