1. Guinea fowl hens were inseminated weekly once with two doses of spermatozoa (75 million and 100 million) in two different diluents, Beltsville poultry semen extender (BPSE), and Instruments for Veterinary Medicine (IMV), each with and without pre-insemination vaginal douching. Per cent fertility, hatchability, dead germ, dead in shells along with data on sperm egg interaction and vaginal microbial counts were recorded.
2. Artificial insemination had significantly improved the per cent fertility and hatchability compared to natural mating. Dose dependent improvement in fertility was noticed with both diluents.
3. There was a beneficial effect of vaginal douching, which was more pronounced at lower insemination doses.
4. For optimum fertility and hatchability in guinea fowl, insemination of 75 million spermatozoa diluted in BPSE once in 4 d and 100 million spermatozoa diluted in BPSE or IMV once in 5 d coupled with vaginal douching is recommended.
The first reports of glyphosate‐resistant (GR) sourgrass (Digitaria insularis) came from Paraguay (2005) and from South and Southeast Brazil, in Paraná (2008), and São Paulo state (2009). The hypothesis of this research is that the evolution of these resistant populations might have occurred independently. To test this hypothesis, a dose–response experiment was conducted in order to confirm resistance and inter simple sequence repeat markers subsequently were evaluated in five sourgrass populations from Paraguay (PY‐R), Paraná (PR‐S and PR‐R), and São Paulo (SP‐S and SP‐R). Resistant populations were confirmed in PY‐R, PR‐R and SP‐R. The resistant populations presented lower polymorphism than susceptible populations, possibly related to the selection pressure exerted by the herbicide. Both similarity matrix and dendrogram provided evidences that the origin of resistance in the populations from Paraguay and Paraná could be the same, which also is explained by their geographical proximity. In contrast, the evolution of GR populations in São Paulo was suggested to occur independently from other locations because resistance evolved in genetically divergent populations. This study’s data provide evidences that GR sourgrass populations from Paraguay and Paraná share a similar genetic background; therefore, it is possible that resistance from Paraguay spread to Paraná through gene flow. The population from São Paulo probably was selected independently because the high values of its genetic structure and low level of gene flow. Independent selections and seed dispersion of GR sourgrass have contributed to the rapid spread of resistance across South America. 相似文献
A number of molecular marker technologies have allowed important advances in the understanding of the genetics and evolution
of Eucalyptus, a genus that includes over 700 species, some of which are used worldwide in plantation forestry. Nevertheless, the average
marker density achieved with current technologies remains at the level of a few hundred markers per population. Furthermore,
the transferability of markers produced with most existing technology across species and pedigrees is usually very limited.
High throughput, combined with wide genome coverage and high transferability are necessary to increase the resolution, speed
and utility of molecular marker technology in eucalypts. We report the development of a high-density DArT genome profiling
resource and demonstrate its potential for genome-wide diversity analysis and linkage mapping in several species of Eucalyptus. 相似文献
Microbial enzyme activities were followed during a field-based experimental simulation of the effects of higher rainfall
in a Welsh peatland. The treatment did not significantly affect the activities of the carbon cycling enzymes, β-glucosidase,
esterase or xylosidase. In contrast, the activity of the enzyme sulphatase decreased by 44% (P<0.001) in response to the wetter conditions. The manipulation suggests that should climate change cause conditions to become
wetter in peatlands, then (with the exception of sulphatase) current levels of wetness may be sufficient to limit decomposition
processes, and thus any further increase in wetness is unlikely to induce a further decrease in decomposition rates. Correlations
were found between the esterase activity and both nitrous oxide flux (r=–0.44, P<0.05), and methane release (r=0.53, P<0.01). Likewise, there was a correlation between xylosidase activity and both carbon dioxide emission (r=0.52, P<0.01) and aluminium concentration (r=0.58, P<0.01). All of the enzymes correlated positively with dissolved organic carbon (range r=0.53, P<0.01 sulphatase to r=0.61, P<0.001 glucosidase). Together, the correlations lend support to recent hypotheses suggesting that enzymes exert an influence
over wetland biogeochemical properties.
Received: 29 May 1997 相似文献
The land use and climate of Scotland are currently undergoing change. Concentrations of Natural abundance stable isotopes in ecosystems have been used extensively to help to understand a wide range of processes and functions. In the current study topsoil was collected from the intercepts of a 20‐km grid across the whole of Scotland (183 points), which encompass large differences in mean annual temperature (MAT,3.1–9.1°C), mean annual precipitation (MAP, 588–3470 mm) and land use (from arable land through grassland and woodland to less fertile moorlands and bogs). At each sampling point the natural abundance δ13C and δ15N values were measured. This paper describes for the first time the spatial distribution of these isotopes in the topsoil of Scotland. We applied linear modelling to assess the extent to which land use and climate can control the observed distributions. The more enriched topsoil δ13C values occurred in the northern and western regions of Scotland. Topsoil δ13C values were tightly constrained about the mean, and possibly because of this we were able to explain only 23.6% of the variance even after considering the potential effects of a wide range of abiotic factors and land uses. Precipitation and land use explained the greatest variance in topsoil δ13C, but individually this was only 10.4 and 9.9%, respectively. Topsoil δ15N values showed a more complex spatial arrangement. The main areas of the more enriched δ15N values were in the northern isles, along or near the coast on the eastern side of the country and in some areas of the western mainland. For topsoil δ15N, all explanatory variables together explained 55.7% of the variance, with land use alone explaining 45.4%. Soil under arable land and improved grassland, the more fertile sites, had the most enriched δ15N values, whereas woodland and bogs had the most depleted values. A positive relationship between topsoil δ15N and potential rate of nitrification suggested that this was due, at least in part, to greater losses of nitrate under arable land and improved grassland. 相似文献
Single-wall fullerene nanotubes were converted from nearly endless, highly tangled ropes into short, open-ended pipes that behave as individual macromolecules. Raw nanotube material was purified in large batches, and the ropes were cut into 100- to 300-nanometer lengths. The resulting pieces formed a stable colloidal suspension in water with the help of surfactants. These suspensions permit a variety of manipulations, such as sorting by length, derivatization, and tethering to gold surfaces. 相似文献