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31.
Repeated ultrasonographic examinations and collections of blood samples and uterine lumenal swabs between seven and 28 days after calving were used to examine the relative effects of bacterial contamination and involution of the uterus on the concentrations of acute phase proteins in the blood of 26 dairy cows. The severity of bacterial contamination, as determined by the total bacterial growth score, was a significant variable for the concentrations of the acute phase proteins alpha1-acid glycoprotein (P < 0.0001), haptoglobin (P < 0.05) and ceruloplasmin (P < 0.0001). In addition, the concentrations of alpha1-acid glycoprotein and ceruloplasmin were increased in the cows from which Escherichia coli (P < 0.0001) and Arcanobacterium pyogenes (P < 0.05), respectively, were isolated from the uterine lumen. Uterine involution, as determined by the decreasing diameter of the previously gravid uterine horn, was associated with a decrease in the concentrations of alpha1-acid glycoprotein (P < 0.005), haptoglobin (P < 0.05) and ceruloplasmin (P < 0.01). However, the response of the acute phase proteins to bacterial contamination was independent of the day on which the samples were collected, indicating that their concentrations were increased by bacterial contamination in addition to the changes associated with uterine involution. 相似文献
32.
Hd3a protein is a mobile flowering signal in rice 总被引:7,自引:0,他引:7
Florigen, the mobile signal that moves from an induced leaf to the shoot apex and causes flowering, has eluded identification since it was first proposed 70 years ago. Understanding the nature of the mobile flowering signal would provide a key insight into the molecular mechanism of floral induction. Recent studies suggest that the Arabidopsis FLOWERING LOCUS T (FT) gene is a candidate for encoding florigen. We show that the protein encoded by Hd3a, a rice ortholog of FT, moves from the leaf to the shoot apical meristem and induces flowering in rice. These results suggest that the Hd3a protein may be the rice florigen. 相似文献
33.
Densities of 26 submergent macrophyte species were determined in situ regularly for 3 years by individuals using self-contained underwater breathing apparatus (scuba). Although most of these species grew only during the summer, ten maintained high population densities and productivity throughout the winter. Maximum winter photosynthetic activity was 10 to 20 percent of summer rates. Extensive productivity of submergent aquatic plants under winter ice cover has not been well documented. 相似文献
34.
Hackett SJ Kimball RT Reddy S Bowie RC Braun EL Braun MJ Chojnowski JL Cox WA Han KL Harshman J Huddleston CJ Marks BD Miglia KJ Moore WS Sheldon FH Steadman DW Witt CC Yuri T 《Science (New York, N.Y.)》2008,320(5884):1763-1768
Deep avian evolutionary relationships have been difficult to resolve as a result of a putative explosive radiation. Our study examined approximately 32 kilobases of aligned nuclear DNA sequences from 19 independent loci for 169 species, representing all major extant groups, and recovered a robust phylogeny from a genome-wide signal supported by multiple analytical methods. We documented well-supported, previously unrecognized interordinal relationships (such as a sister relationship between passerines and parrots) and corroborated previously contentious groupings (such as flamingos and grebes). Our conclusions challenge current classifications and alter our understanding of trait evolution; for example, some diurnal birds evolved from nocturnal ancestors. Our results provide a valuable resource for phylogenetic and comparative studies in birds. 相似文献
35.
Digested sludge contains valuable crop nutrients but these are largely lost because current application techniques limit where and when it can be applied. Soil injection to depths in excess of 150 mm to reduce odour problems can only be used on fallow land or grass because of the damage it can cause. This leads to applications at high rates being applied with increased environmental risk. The aim of this study was to determine the benefits and limitations of injecting digested sewage sludge into land growing arable crops using shallow, less than 100 mm deep, injection techniques. Agronomic trials conducted over 2 years with winter wheat and rape showed that the crops were surprisingly resistant to mechanical damage during the growing season. Crop yields were not effected by injecting sludge into the crop up to March, equivalent to growth stage 30 in winter wheat, using a conventional tractor-based system working. Injection is possible later in the growing season based on systems with the tractor operating along “tramlines” for field traffic control. 相似文献
36.
Alison R. Styring Roslina Ragai Joanes Unggang Robert Stuebing Peter A. Hosner Frederick H. Sheldon 《Forest Ecology and Management》2011,261(3):531-544
Plantations of exotic trees for industrial and agricultural purposes are burgeoning in the tropics, and some of them offer the opportunity to study community ecology of animals in a simplified forest setting. We examined bird community assembly in different aged groves of the industrial tree mangium (Acacia mangium) at two plantations in Malaysian Borneo: Sabah Softwoods near Tawau, Sabah, and the Planted Forest Project, near Bintulu, Sarawak. Bird communities were compared among three age-groups of mangium (2-, 5-, and 7-years old) and logged native forest. Mangium rapidly developed into a secondary forest consisting of a wide diversity of understory trees and shrubs. The bird community correspondingly increased in species richness and diversity, and we were able to relate these increases specifically to canopy height, secondary canopy development, and shrub cover. Species of common, small bodied frugivores, nectarivores, and insectivores were diverse in older plantation groves, as were common mid-sized insectivores. However, large, specialized, and normally uncommon taxa (e.g., galliforms, pigeons, hornbills, barbets, midsized woodpeckers, muscicapine flycatchers, and wren babblers) were rare or nonexistent in the plantations. Because we lacked species-specific data on foraging, nesting, and other behaviors of most groups of birds, it was difficult to explain the precise causes of seral diversification in any group except woodpeckers, which have been well studied in Southeast Asia. Thus, in future, particular emphasis needs to be placed on obtaining such data. Industrial plantations, by virtue of their simple structure, variably aged groves, and bird community richness, are good places to gather such data. 相似文献
37.
Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was employed to examine the chemical emissions from the glued wood
samples at elevated temperatures (150, 200, 250, 300, 350, 400, 450, and 500°C). Two wood species, Douglas-fir (Pseudotsuga menziesii) and southern pine (Pinus palustris), one structural adhesive, phenol–resorcinol–formaldehyde (PRF), PRF-bonded Douglas-fir, and PRF-bonded southern pine were
evaluated. The volatile compounds with a mass range of 35–300 m/z emitted from the pyrolysis samples were separated by gas
chromatography (GC) and identified by mass spectrometry (MS). The results indicated that compared to neat wood and resin film
samples, several additional pyrolysis products were observed for the PRF-bonded wood samples including (1) acetaldehyde and
butanedial for PRF-bonded Douglas-fir and (2) acetaldehyde, furfural, 2-furanmethanol, butanedial, 2,3-butanedione, cyclopropyl
carbinol, 1,2-benzenediol, and 1-(acetyloxy)-2-propanone for PRF-bonded southern pine. These additional compounds were possibly
associated with the interaction between wood and PRF resin. The results also indicated that bonded wood products would be
less thermally stable than those of neat wood and PRF resin samples. 相似文献
38.
Judith Nyiraneza Bernie J. Zebarth Sherry A.E. Fillmore Mohammad Khakbazan Sheldon W.R. Hann Josée Owen 《Communications in Soil Science and Plant Analysis》2020,51(11):1499-1513
ABSTRACT In humid climates, the risk of nitrate leaching and topsoil loss due to erosion is high on bare soil in the fall after potato (Solanum tuberosum L.) harvest and in the spring with snowmelt. This 2-year study (2016–2017) compared three winter cover crops. Two of these are used as cash crops (winter rye [Secale cereale L.], winter wheat [Triticum aestivum L.]), and one is a winter-killed cover crop (spring barley, Hordeum vulgare L.). They were all seeded on two dates after potato harvest (end of September or first week of October) in Prince Edward Island, Canada. The measured parameters included soil nitrate measured at different times in fall and in the following spring and summer, splash detachment, C and N contents in splashed sediments, cereal straw dry matter yield, and cereal grain yield. In both years, all winter cover crops decreased splash detachment compared with the no winter cover control, with winter rye having the greatest reduction. A similar trend was observed for C and N contents in splashed sediments. There was a trend toward lower soil nitrate following winter cover crops in comparison with bare soil, but the trend was not consistent across trials and sampling dates. Winter wheat grain yield ranged from 4.5 to 7.6 Mg ha?1, while that associated with winter rye ranged from 3.2 to 5.1 Mg ha?1. Therefore, winter cereal seeded after potato harvest can constitute a good source of revenue while mitigating the risk of soil erosion and reducing nitrate leaching in some cases. 相似文献
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