基于SNP和InDel标记的巴西木薯遗传多样性与群体遗传结构分析

为了对巴西木薯种质资源进行遗传多样性、亲缘关系和群体遗传结构分析,本研究利用了7946个SNPs和1997个InDels分子标记,通过ADMIXTURE软件进行群体结构分析、GCTA软件进行主成分分析。结果显示,巴西木薯被划分为9个亚群。这与利用PHYLIP进行的聚类分析结果大概一致,其中亚群1、亚群2、亚群4、亚群6和亚群8能较好地分别聚在一起,而其他亚群中的样品大致能聚在一起,且样品间有一定的交叉。巴西木薯种质资源遗传多样性指数(0.274)高于中国、尼日利亚等,其中巴西木薯亚群5具有相对较高的遗传多样性水平(0.29)。巴西木薯各亚群的群体遗传分化程度较低(群体分化指数在0.03~0.15之间),但高于中国木薯种质资源的群体分化指数。各木薯材料间的遗传距离变幅为0.084~0.297,平均遗传距离为0.228。本研究结果可为后续关联分析发掘优良等位基因及引种提供依据。     

Emerging avian pathogenic Escherichia coli strains belonging to clonal groups O111:H4-D-ST2085 and O111:H4-D-ST117 with high virulence-gene content and zoonotic potential

The present study characterizes, for the first time, two emerging avian pathogenic Escherichia coli (APEC) clonal groups of serogroup O111: O111:H4-D-ST117 and O111:H4-D-ST2085. The clonal group O111:H4-D-ST117 was already present in APEC strains isolated between 1991 and 2000, and was still present in strains isolated between 2004 and 2009, showing long time evolution according to the virulence-gene differences and macrorestriction profiles. Among ST117 strains, two virulence profiles could be distinguished: papG II-positive tsh-negative strains which satisfied criteria for extraintestinal pathogenic E. coli (ExPEC), and papG II-negative tsh-positive strains without ExPEC status. Interestingly, we have detected a human septicemic O111:H4-D-ST117 ExPEC strain isolated from a hemocultive in 2000 whose macrorestriction profile showed >85% similarity with four APEC strains of the study. The clonal group O111:H4-D-ST2085 was exclusively detected in 17 APEC strains isolated in 2008 and 2009, and showed short time evolution based on its homogeneity since all were nalidixic acid-resistant, all had ExPEC status, and most carried papG II and tsh genes. From the clinical point of view, O111:H4-D-ST2085 seems a successful clonal group that could be the result of the epidemiological evolution of O111:H4-D-ST117. Due to the increasing prevalence of both clonal groups among clinical APEC isolates, their high virulence-gene content, and zoonotic potential, we suggest them as possible candidates for the development of a future vaccine against avian colibacillosis.     

Comparison of the calving-to-conception interval in dairy cows with different degrees of lameness during the prebreeding postpartum period

OBJECTIVE: To compare calving-to-conception intervals among cows classified as nonlame, moderately lame, or lame during the prebreeding postpartum period and to examine the relationship between severity of lameness and time to conception in cows that were classified as lame. DESIGN: Longitudinal study. ANIMALS: 499 Holstein cows. PROCEDURE: Cows in the prebreeding postpartum period were classified as nonlame, moderately lame, or lame by use of a 6-point locomotion scoring system. Time to conception (days) was compared among cows. A low, medium, or high cumulative locomotion score was assigned to lame cows, and time to conception among those cows was compared. Cows classified as lame were examined on a tilt table for diagnosis and treatment of lameness. RESULTS: 154 (31%), 214 (43%), and 131 (26%) cows were classified as nonlame, moderately lame, and lame, respectively. Most cows classified as lame had laminitis (54%) or disorders of the claw (33%). Median time to conception was 36 to 50 days longer in lame cows than in nonlame cows. Among lame cows, the median time to conception was 66 days longer in cows with high cumulative locomotion scores than in cows with low scores. CONCLUSION AND CLINICAL RELEVANCE: Nonlame cows became pregnant more quickly than lame cows. Lame cows with low cumulative locomotion scores during the prebreeding postpartum period became pregnant sooner than lame cows with high scores. Early diagnosis and intervention may mitigate the effects of lameness and improve reproductive performance in lame dairy cows.     

Fecundity in adult Haemonchus contortus parasites is correlated with abomasal tissue eosinophils and γδ T cells in resistant Canaria Hair Breed sheep

Canaria Hair Breed (CHB) sheep are more resistant than Canaria sheep (CS) to experimental Haemonchus contortus infection. Protective responses appear effective against the adult stage of the parasite, not as commonly reported in other breeds against the larval stages. In this study we have quantified several abomasal immune cells and correlated these with parasitological variables for each breed. A significant negative correlation between CD4+ T cell numbers and worm burden or length at 28 dpi was seen only in CS sheep. Significant negative correlations for both abomasal eosinophils and γδ/WC1+ T cells, and fecundity of the adult worms were observed only in the resistant CHB sheep breed. Tissue eosinophils and γδ/WC1+ T cells were positively correlated in CHB sheep. We suggest that the two sheep breeds have disparate immune responses following infection with the parasite and that γδ+ T cells in association with eosinophils may play a hitherto unrecognised role in modulating fecundity in H. contortus adult female parasites.     

Changes in microbial biomass and microbial activity of pig slurry after the transit through the gut of the earthworm Eudrilus eugeniae (Kinberg, 1867)

Here we studied the effects of gut transit through the earthworm Eudrilus eugeniae, on the physicochemical, biochemical, and microbial characteristics of pig slurry, by analyzing fresh casts. The reduction in the dissolved organic C contents in casts we recorded suggests that during digestion, earthworms assimilated labile organic C preferentially, which is a limiting growth factor for them. Furthermore, both microbial biomass and activity in pig slurry were significantly decreased by earthworm gut transit. It appears that E. eugeniae is able to digest microorganisms, although the addition of glucose to the food increased respiration, indicating that growth of microorganisms in casts could be limited by depletion of labile C. Despite reduced microbial biomass and activity, the metabolic diversity of microbial communities was greater in casts than in original pig slurry. Community level physiological profiles obtained from Biolog Ecoplate data revealed that, after earthworm gut transit, the microbial communities in casts and pig slurry were clearly differentiated by their physiological profiles. The results indicate that first stage in vermicomposting of pig slurry by E. eugeniae, i.e., casting, produced changes that will influence the dynamics of the organic matter degradation by reducing forms of N and C available to microorganisms, hence restricting their growth and multiplication. Nevertheless, the reduced microflora of casts was characterized by an increased catabolic potential that might lead to thorough degradation of pig slurry.     

Effect of 17α-Methyltestosterone and 17α-Hydroxyprogesterone on the Quality of White Shrimp Penaeus vannamei Spermatophores

Abstract.— Controlled reproduction of penaeid shrimp requires a better utilization of males by sperm quality monitoring and sperm quality improvement. Spermatophores of white shrimp Penaeus vannamei were improved, in terms of increased sperm count, spermatophore weight, and a reduced incidence of sperm abnormalities by a single injection of 17α-methyltestosterone at 0.01 or 0.1 μg/g body weight. 17α-hydroxyprogesterone did not induce a significant improvement in spermatophore quality. These findings indicate that a steroid injection program should be evaluated as a practical way of improving spermatophore quality in commercial operations.     

Utilization of Gracilaria chilensis (Rhodophyta: Gracilariaceae) as a Biofilter in the Depuration of Effluents from Tank Cultures of Fish, Oysters, and Sea Urchins

An evaluation was made on a seasonal basis of the effect of the marine macroalga culture Gracilaria chilensis on concentrations of some soluble and particulate wastes emitted during tank cultures of a fish Isacia conteptionis , an oyster Crassostrea gigas , and a sea urchin Loxechinus albus species. The animals were each cultured in separate tanks, and effluent from each was directed through separate tanks, which contained dense cultures of the Gracilaria chilensis . Inflow-outflow monitoring was conducted for the presence of nitrate, nitrite, ammonium, and phosphate. Also evaluated were particulate nitrogen and phosphate. The most significant wastes were ammonium from the fish culture and nitrate from the oyster culture. These were completely removed from the water, with minor exceptions, by the alga during all seasons of the year. Lesser amounts of soluble phosphate and nitrite, arising from the fish cultures, were also removed. Of the particulate matter, only nitrogen was in evidence from the fish cultures in the summer. It was concluded that Gracilaria chilensis culture was highly efficient at biofiltration of the soluble nutrients tested but had little effect on particulate emissions. The best growth of Gracilaria chilensis occurred in the ammonium-rich effluent from the fish culture.     

Genetic variation, mating patterns and gene flow in a Pinus pinaster Aiton clonal seed orchard

? Relatedness among parents, variation in clonal fertility and background pollination deviate the realized genetic gain and the gene diversity of open pollinated seed orchard from expectation, in particular in wind pollinated species such as Pinus pinaster Aiton.

? This work investigates the genetic variation, the mating system and the pollen contamination in a P. pinaster clonal seed orchard (CSO), by screening the 60 clones from the CSO and the seeds collected from 21 mother-trees with three nuclear microsatellites.

? The expected diversity was similar, but the observed heterozygosity decreased 20% in the progenies compared with the parental trees. The outcrossing rate was 90.1%, the biparental inbreeding 21.7% computed through a multilocus approach, and the observed selfing 3.9%. The observed gene flow from outside the CSO was 52.4%.

? From the results we concluded that the observed gene flow and the biparental inbreeding were high, and care should be taken in the implementation and management of future CSO, in particular clones should be checked for relatedness and the ramet number could be directly proportional to their breeding value.

     

Characterizing the setting of cement when mixed with cork, blue gum, or maritime pine, grown in Portugal I: temperature profiles and compatibility indices

Data are presented on the effects that cork, blue gum, or maritime pine, all grown in Portugal, have on cement setting. These materials were mixed with cement either without any treatment or after being extracted previously with a range of solvents (ranging from nonpolar to very polar). Other experiments were carried out in which extractives or calcium chloride were added to the cement paste. All lignocellulosic substrates have detrimental effects on cement setting, which is mostly seen by a delay in attaining the maximum temperature in the process. However, the addition of calcium chloride was able to overcome this disadvantage. Extraction of the substrates with some polar extraction agents before addition to the cement paste only slightly improved compatibility, and the addition of water-based extractives to a cement paste affects the setting much less than the lignocellulosic material by itself. Several thermal compatibility indices, including a new index proposed in this article, were calculated from data taken from temperature profiles, and conclusions are presented on the performance of the setting systems, as compared with a neat cement paste. In addition, comments are expressed on the level of accuracy offered by the indices applied in this study, and how such accuracy can be checked or improved by matching them to the physical properties of the wood-cement composites.