Effects of partial drying of an udder quarter in cows with teat injuries     

P Rüsch  M Berchtold  H Burkhardt  A Mittelholzer 《DTW. Deutsche tier?rztliche Wochenschrift》1990,97(10):385-386

In cows with teat lesions, partial drying-off of the affected mammary quarter is recommended for a period of 3 to 10 days. The other three quarters are normally milked. Partial drying-off reduces the risks of complications due to the daily milking. The slight reduction of milk production, connected with the temporary drying-off a single quarter, is nearly compensated within 4 weeks.  相似文献   

A simple bioassay for detecting and characterising insecticide resistance     

Jeffrey R. Bloomquist  Thomas A. Miller 《Pest management science》1985,16(6):611-614

A simple and rapid paralysis assay was developed to detect and characterise knockdown resistance in larvae of the house fly and pink bollworm. Pyrethroidtreated larvae unable to perform a stereotypic curling movement when probed with a warm needle, 10 min (house fly) or 60 min (pink bollworm) after treatment, were considered to be paralysed. Responses in a susceptible strain of house fly were compared with those of the pyrethroid-resistant strains kdr and super-kdr. In this assay, the kdr strain displayed over 28 fold resistance to deltamethrin, and super-kdr larvae were unaffected by doses up to 100μg. These results are in good qualitative agreement with previous studies. The assay detected no significant fenvalerate resistance in pink bollworm larvae collected from the field; this was consistent with mortality bioassays performed on wild adult males. The limitations and potential utility of the paralysis bioassay in resistance screening are discussed.  相似文献   

Histologic and histochemical changes in articular cartilages of immature beagle dogs dosed with difloxacin, a fluoroquinolone   总被引：6，自引：0，他引：6  

J E Burkhardt  M A Hill  W W Carlton  J W Kesterson 《Veterinary pathology》1990,27(3):162-170

The histologic and histochemical features of quinolone-induced arthropathy were studied using 14 skeletally immature Beagle dogs (3 to 4 months old) dosed orally with difloxacin at 300 mg/kg body weight once daily for 1, 2, 5, or 7 days. A placebo was given to eight other age-matched Beagle dogs that served as controls. A scoring technique that included lesion size and histologic features was used to determine the progression of lesions. Articular-epiphyseal cartilage complexes on the femoral and humeral heads and tibial tarsal bone were identified as predilection sites. Within predilection sites on femoral and humeral heads, lesions developed in specific areas. Lesions appeared within 2 days of the onset of treatment, and lesion scores increased with time. Grossly, the lesions were raised, fluid-filled vesicles on the articular surface. Histologic changes included vesicle formation with loss of proteoglycan, clumping of unmasked collagen, and degeneration and necrosis of chondrocytes. In lesions with higher scores, chondrocytes were often in clusters or they were undergoing metaplasia toward spindle-shaped cells. Although dissolution of matrix and necrosis of chondrocytes were typical of all lesions, smaller lesions had histologically normal chondrocytes adjacent to small vesicles. In sections stained with toluidine blue, proteoglycan was aggregated with collagen fibrils or was absent from the matrix adjacent to vesicles. Unique features, such as biomechanical forces, may predispose specific areas of articular cartilage to develop lesions.  相似文献   

Sources and inheritance of earliness in tropically adapted indeterminate common bean     

Jeffrey W. White  Shree P. Singh 《Euphytica》1991,55(1):15-19

Summary Nineteen early maturing, indeterminate common bean parents were crossed with a tester line of normal maturity. All parents, F₁ hybrids, F₂'s, and backcross generations were evaluated at CIAT-Palmira, Colombia. All 19F₁ populations flowered and matured almost as early as the respective early parent (mean of 61 vs 59 days). The F₂ populations were slightly less early (63 days), but were still earlier than the mean of the two parents (65 days). Additive effects for days to maturity were usually larger than dominance or interaction effects. Narrow sense heritability for days to flower and maturity were high (greater than 0.67), while heritabilities of absolute and relative duration of pod filling were low (0.17 to 0.50). Also, our data indicated that for each day of increase in earliness, yield potential will decrease 74 kg/ha.  相似文献   

Genetic engineering of Indica rice in support of sustained production of affordable and high quality food in developing countries     

I. Potrykus  P. K. Burkhardt  S. K. Datta  J. Fütterer  G. C. Ghosh-Biswas  A. Klöti  G. Spangenberg  J. Wünn 《Euphytica》1995,85(1-3):441-449

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As the world gets smaller, the chances of invasion grow     

Jeffrey A. McNeely 《Euphytica》2006,148(1-2):5-15

Summary While the issue of invasive alien species has important biological components, economic factors such as global trade deserve much greater attention for several reasons. First, virtually all of our planet’s ecosystems have a strong and increasing anthropogenic component that is being fed by increasing globalisation of the economy. Second, people are designing the kinds of ecosystems they find productive or congenial, incorporating species from all parts of the world through quicker and more efficient means of transportation. And third, growing travel and trade, coupled with weakening customs and quarantine controls, mean that people are both intentionally and inadvertently introducing alien species that may become invasive. The great increase in the introduction of alien species that people are importing for economic, aesthetic, accidental, or even psychological reasons is leading to more species invading native ecosystems, with disastrous results: they become invasive alien species (IAS) that have significant deleterious effects on both ecosystems and economies. This paper examines some of the important non-biological dimensions of the IAS problem, including historical, economic, cultural, linguistic, health, sociological, management, legal, military, ethical, and political dimensions. These are addressed in terms of the causes, consequences, and responses to the problem of IAS. These dimensions of IAS are fundamental, and successfully addressing the problem will call for greater collaboration between different economic sectors and among a wide range of disciplines. The Convention on Biological Diversity, the negotiations of the World Trade Organisation, and many other international agreements offer important opportunities for addressing the complex global problems of IAS through improved international cooperation.  相似文献   

Effect of selection for pollen grain size on various traits in common bean     

Consuelo Montes-R  Jeffrey W. White 《Euphytica》1996,90(1):59-63

Summary Selection among microgametophytes usually exploits variation in pollen grain germination. Studies of variation in pollen grain size in common bean (Phaseolus vulgaris L.) suggested that selection for size might lead to changes in sporophytic traits. To determine whether microgametophytic selection based on size would affect pollen grain size in subsequent generations or sporophytic traits that were correlated with pollen grain size, pollen grains from three crosses were separated into two size categories by sieving and then used to pollinate cv. Diacol Calima. Selection resulted in changes in pollen grain diameter for pollen from F₁, F₂ and F₃ plants for all crosses. In vitro germination indicated no differences between vigor of large and small grains, but extraction and sieving reduced germinability. F₁ seed from two of the crosses with size-selected pollen varied in weight according to pollen grain size, but in subsequent generations, the effect disappeared. Both size categories of selected pollen resulted in F₂ progeny with reduced numbers of seeds per pod as compared to controls, suggesting that the size selection process may have resulted in indirect selection for traits reducing seed set. The overall results suggested that genes determining pollen grain size in bean have little or no effect on sporophytic traits such as seed size and seed yield.  相似文献   

Effect of tissue culture explant source on sugarcane yield components     

Jeffrey W. Hoy  Keith. P. Bischoff  Scott. B. Milligan  Kenneth. A. Gravois 《Euphytica》2003,129(2):237-240

Clonal propagation of sugarcane(interspecific hybrids of Saccharum)is conducive to spread of systemicdiseases, such as ratoon stunting disease,caused by Leifsonia xyli subsp. xyli. This important disease iscontrolled by obtaining and plantinghealthy seed-cane. In Louisiana, commercialseed-cane initially produced through tissueculture is available to sugarcane farmersand is being widely planted. Long-termacceptability of this seed-cane productionmethod depends on the production of healthyplants that do not differ significantly inphenotypic and yield characteristics fromthe clones originally selected and releasedas commercial cultivars. To determinewhether tissue culture affects yield or itscomponents, three cultivars, CP 70-321, LCP85-384, and HoCP 85-845, were compared inthree successive crops initially plantedwith stalks from three sources: plantsderived from callus culture of the leafroll above the apical meristem, directregeneration from the apical meristem, andconventional bud propagation. Stalks ofplants derived from both explant sourceswere typical of seed-cane farmers wouldpurchase for planting that had beenpreviously rogued for phenotypic variantsand increased by bud propagation.Differences in yield components amongtissue culture explant sources and budpropagated cane only occurred in CP 70-321.Stalk diameter and stalk weight were lowerand stalk population was higher for plantsderived from leaf roll callus compared tobud propagated cane. Yield components weresimilar for plants derived from an apicalmeristem and bud propagation. Individualplant phenotypic variants resulting fromsomaclonal variation were not observed inany of the cultivars derived from eitherexplant source. In summary, genotype andexplant source affected persistent, uniformphenotypic variation resulting from tissueculture that changed some yield components. However, apical meristem culture wassuitable for production of seed-cane, assugarcane derived by meristem culture ofthree cultivars did not differsignificantly from the original germplasmfor any measured yield trait.  相似文献   

Quantitative approaches to nutrient density for public health nutrition     

Backstrand JR 《Public health nutrition》2003,6(8):829-837

Nutrient density, the vitamin or mineral content of a food or diet per unit energy, has long been a useful concept in the nutritional sciences. However, few nutritionists have applied the idea in quantitative, population-based nutrition planning and assessment. This paper discusses the conceptual issues related to the calculation of a nutrient density value that, if consumed, should meet the nutrient needs of most individuals in a population or sub-population, and outlines several methods for estimating this value. The paper also discusses the potential influence on the estimate's validity of factors such as skewed distributions and correlated energy intake and nutrient requirement.  相似文献   

Soil microbial biomass: its assay and role in turnover of organic matter C and N     

Jeffrey N. Ladd  Maurice Amato 《Soil biology & biochemistry》2004,36(9):1369-1372

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