氧氟沙星药物的研究进展

通过对氧氟沙星药物近十年来的检测方法、药代动力学、药效学、耐药性及抗菌后效应、联合应用及毒理学、残留及残留的检测方法等六个方面的大量研究资料进行综述,详细介绍并论述了氧氟沙星药物在这些方面的最新研究成果,对氧氟沙星药物及其他喹诺酮类药物的进一步研究、开发和应用具有指导意义。     

Assessing in vivo Fertilizing Capacity of Liquid-Preserved Boar Semen According to the 'Hanover Gilt Model'

The goal of this study was to determine the ability of the Hanover gilt model to assess in vivo fertilizing capacity of preserved sperm and to consider whether any modifications to this model were needed. This model evaluates the fertilizing capacity of semen based on the fertilization rate, the rate of normal embryos and the accessory sperm count of 3–5‐day embryos. Its distinguishing characteristics are the use of one‐time insemination of sperm in reduced numbers, of spontaneously ovulating gilts and of ovulation detection through ultrasound examination of ovaries. Reduced sperm numbers allow for an accurate evaluation of the fertilizing potential of different semen treatments, thereby avoiding the compensatory effect of doses calibrated to maximize fertility. The model's usefulness was assessed in a trial run designed to compare the fertilizing capacity of liquid boar semen diluted into two different extenders. The diluent, the boar and the backflow, had no significant effect on any of the parameters studied. Gilts inseminated less than 24 h before ovulation had a significantly higher (p < 0.01) fertilization rate and accessory sperm cell count (p < 0.05) than those inseminated more than 24 h before ovulation. Very good/good embryos from homogeneous litters (only very good/good embryos were present) had a significantly higher (p < 0.01) accessory sperm count than those from heterogeneous litters (at least one embryo was of a different quality and/or oocytes were present). Both very good/good and degenerated/retarded embryos from heterogeneous litters had low accessory sperm numbers. This suggests that accessory sperm count is significantly related to the quality of the litter, but not to the quality of the embryo within gilts. It can be concluded that the Hanover gilt model is sensitive enough to show fertility differences (in this study, those associated with in vivo ageing of semen), while using relatively few gilts and little time.     

RADIX: rhizoslide platform allowing high throughput digital image analysis of root system expansion

Background

Phenotyping of genotype-by-environment interactions in the root-zone is of major importance for crop improvement as the spatial distribution of a plant’s root system is crucial for a plant to access water and nutrient resources of the soil. However, so far it is unclear to what extent genetic variations in root system responses to spatially varying soil resources can be utilized for breeding applications. Among others, one limiting factor is the absence of phenotyping platforms allowing the analysis of such interactions.

Results

We developed a system that is able to (a) monitor root and shoot growth synchronously, (b) investigate their dynamic responses and (c) analyse the effect of heterogeneous N distribution to parts of the root system in a split-nutrient setup with a throughput (200 individual maize plants at once) sufficient for mapping of quantitative trait loci or for screens of multiple environmental factors. In a test trial, 24 maize genotypes were grown under split nitrogen conditions and the response of shoot and root growth was investigated. An almost double elongation rate of crown and lateral roots was observed under high N for all genotypes. The intensity of genotype-specific responses varied strongly. For example, elongation of crown roots differed almost two times between the fastest and slowest growing genotype. A stronger selective root placement in the high-N compartment was related to an increased shoot development indicating that early vigour might be related to a more intense foraging behaviour.

Conclusion

To our knowledge, RADIX is the only system currently existing which allows studying the differential response of crown roots to split-nutrient application to quantify foraging behaviour in genome mapping or selection experiments. In doing so, changes in root and shoot development and the connection to plant performance can be investigated.

     

Segregation of microsatellite loci in second generation hybrid striped bass (<Emphasis Type="Italic">Morone saxatilis</Emphasis> × <Emphasis Type="Italic">Morone chrysops</Emphasis>)

Within the framework of a larger project aimed to assess the potential of second generation hybrid striped bass for German aquaculture the genotypic segregation of five microsatellite loci was analysed in two progeny lots (n = 74 and 76, respectively). There was no consistent correlation between microsatellite genotypes and phenotypic category (white bass, hybrid, or striped bass). None of the individuals expressed neither only white bass nor only striped bass genotypes at all five loci. On the other hand, only hybrid genotypes at all five loci were detected in three individuals of lot 1 and four individuals of lot 2. Single loci tests for conformity of microsatellite genotypic segregation with Mendelian rules revealed significant deviations (P < 0.05) in four cases for lot 1 and in three cases for lot 2. If pooled over all five loci, both lots displayed highly significant deviations (P < 0.01) with an excess of hybrid genotypes and a deficiency of white bass genotypes. It is concluded that stabilizing selection performed on hybrid genotypes might be a suitable approach for practical aquaculture in Europe if the goal is to become independent of first generation hybrid fry supply and/or if establishing domesticated brood stocks of both parental species is impossible. However, more detailed studies on the characteristics and performance of multiple hybrid generations are needed.     

The comparative pathogenicity of four serovars of Actinobacillus (Haemophilus) pleuropneumoniae

The pathogenicity of 2 isolates of each of serovars 7, 3, 1 and 2 of Actinobacillus pleuropneumoniae was tested by intranasal inoculation into 60, 6-week-old large white pigs. Four dose rates varying from 0.27 to 560 x 10(6) organisms per pig with 10-fold serial dilutions were used. Surviving pigs were necropsied 7 days after inoculation. The proportion of pigs dying and developing gross lesions following infection was significantly greater for pigs given serotype 1 than for each of the other 3 serotypes, which did not differ significantly from each other. Twelve of 16 pigs given either of the 2 isolates of serovar 1 died after acute illness and 1 of 44 pigs given either of the 2 isolates each of serovars 7, 3 and 2 died. Pigs given serovar 1 showed high temperatures, severe respiratory distress, frothy haemorrhagic nasal discharge and weight loss. Lung lesions were produced in all 16 pigs given serovar 1, in 7 of 14 pigs given serovar 7, 7 of 14 pigs receiving serovar 3 and in 5 of 16 pigs given serovar 2. The lethal infections were characterised by a severe acute fibrinohaemorrhagic necrotising pleuropneumonia, whereas non-lethal cases had lung lesions ranging from necrotising purulent pleuropneumonia to abscessation. Significant differences between isolates in proportions of tissues culture positive for A. pleuropneumoniae for serovars 7 and 2, but not for serovars 3 and 1 suggested that isolates may vary in virulence within serovars, but more detailed studies are needed to clarify this point.     

A fine-scale chimpanzee genetic map from population sequencing

To study the evolution of recombination rates in apes, we developed methodology to construct a fine-scale genetic map from high-throughput sequence data from 10 Western chimpanzees, Pan troglodytes verus. Compared to the human genetic map, broad-scale recombination rates tend to be conserved, but with exceptions, particularly in regions of chromosomal rearrangements and around the site of ancestral fusion in human chromosome 2. At fine scales, chimpanzee recombination is dominated by hotspots, which show no overlap with those of humans even though rates are similarly elevated around CpG islands and decreased within genes. The hotspot-specifying protein PRDM9 shows extensive variation among Western chimpanzees, and there is little evidence that any sequence motifs are enriched in hotspots. The contrasting locations of hotspots provide a natural experiment, which demonstrates the impact of recombination on base composition.