山羊传染性胸膜肺炎支原体和绵羊肺炎支原体对抗菌药物敏感性的研究

测定了环丙沙星、氧氟沙星、单诺沙星、红霉素、罗红霉素、泰乐菌素、泰妙菌素、四环素等8种药物对羊肺炎支原体两个标准株Y-98和Y-goat的体外抑菌浓度以及红霉素与氧氟沙星、泰乐菌素对Y-goat和四环素与氧氟沙星、泰乐菌素对Y-98的联合药敏作用.结果表明,这8种抗菌药物对Y-goat和Y-98的MIC(μg/mL)分别为:环丙沙星0.223、0.002 23,氧氟沙星0.281、0.014 0,单诺沙星0.136、0.014 0,红霉素0.021 8、无效,罗红霉素0.032 7、无效,泰乐菌素0.042 2、0.039 0,泰妙菌素0.021 7、0.052 0,四环素0.195、0.052 0.红霉素与氧氟沙星的联合药敏指数为1,是相加作用;红霉素与泰乐菌素对Y-goat的联合药敏指数为1.5,是无关作用;四环素与氧氟沙星、泰乐菌素对Y-98的联合药敏试验指数均为0.375,是协同作用.     

In vitro studies of Norwegian Red bovine semen immobilized and cryopreserved in alginate solid gel network

Development of new semen cryopreservation techniques improving sperm survival and ensuring availability of viable spermatozoa for a prolonged time‐period after AI is promising tools to reduce sensitivity of timing of AI and enhance overall fertility. The SpermVital^® technology utilizes immobilization of bull spermatozoa in a solid network of alginate gel prior to freezing, which will provide a gradual release of spermatozoa after AI. The objective of this study was to compare post‐thaw sperm quality and in vitro sperm survival over time of Norwegian Red bull semen processed by the SpermVital^® (SV) technology, the first commercialized production line of SpermVital^® (C) and by conventional procedure applying Biladyl^® extender (B). Post‐thaw sperm motility was not significantly different between SV, C and B semen (p > .05). However, sperm viability and acrosome intactness were higher for SV than C and B semen (p < .05). Small differences in DNA quality were observed (p < .05). Sperm viability after storage in uterus ex vivo was higher for SV than for C semen (p < .05). Furthermore, sperm survival in vitro over time at physiological temperature was significantly higher for SV semen than C semen as well as B semen during the incubation period of 48 hr (p < .05). In conclusion, the SpermVital^® technology is improved and is more efficient in conserving post‐thaw sperm quality and results in higher sperm viability over time in vitro for SV than for C and B semen.     

Some data on selection in tetraploid rye

1. 1.
   Six populations of winter rye were chromosome-doubled in 1951 by means of colchicine. After one generation of multiplication the populations were grown as spaced plants (1954). Records were taken on a number of quantitative characters. Grain yield and number of ears per plant showed very skew distributions, whereas strawlength was approximately normally distributed. Highly significant positive phenotypic correlations were found between grain yield and ear number per plant, and between grain yield per plant and strawlength.     

Pleiotropic effects on the ml-o mildew resistance gene in barley in different genetical backgrounds

Summary The effects on quantitative characters of the ml-o5 allele has been investigated by means of doubled haploid lines produced by the Hordeum bulbosum method. In one series of experiments the genetic background in each cross was found significantly to modify the negative pleiotropic effects. Doubled haploids were also produced from a F1 cross and tested in the field during two years, one with strong and one with weak mildew infections. In the first year only an insignificant reduction in grain yield was detected in the mlo lines, in the second it was significantly reduced with 5.9%. Thousand grain weights were, however, higher in the resistant lines. In both series of experiments the possibility to extract very high yielding mlo genotypes was demonstrated. The nature of the genetic background effect is discussed.     

Genetic variation in cocksfoot (Dactylis glomerata L.) populations for mottle virus resistance

Summary Highly significant and continuous variation in the degree of injury due to cocksfoot mottle virus (CfMV) infection was found among clones of 7 cocksfoot (Dactylis glomerata L.) populations, taken at random among surviving plants in 9 year old swards. Broad sense heritabilities for CfMV injury ranged from 0.52 to 0.91 within populations, and genotypic correlations between CfMV injury and total DM-yield ranged from –0.46 to –0.88. The relationship between CfMV injury and DM-yield could be described by a second degree curve. CfMV injury was to some extent genotypically correlated in the positive direction with crude protein content and digestibility, and negatively with crude fiber content, especially in the first cut. Artificial infection of plants from the original populations with CfMV in a simulated sward experiment, did not reveal any significant differences between populations in tolerance towards CfMV infection. Infection caused a 54.5% increase in the number of dead plants per plot, relative to uninfected plots, but only a 4.5% reduction in dry matter yield. There is a clear tendency that synthetic populations selected for high yield are less tolerant towards CfMV infection than unselected or low yielding populations. The resistance found in these cocksfoot populations is a sort of tolerance, and the results indicate that the level of tolerance can be increased by selection.     

Comparative Earth History and Late Permian Mass Extinction

The repeated association during the late Neoproterozoic Era of large carbon-isotopic excursions, continental glaciation, and stratigraphically anomalous carbonate precipitation provides a framework for interpreting the reprise of these conditions on the Late Permian Earth. A paleoceanographic model that was developed to explain these stratigraphically linked phenomena suggests that the overturn of anoxic deep oceans during the Late Permian introduced high concentrations of carbon dioxide into surficial environments. The predicted physiological and climatic consequences for marine and terrestrial organisms are in good accord with the observed timing and selectivity of Late Permian mass extinction.