产蛋下降综合征微量血凝抑制试验判定标准的确定

用微量血凝抑制试验测定了8个阳性鸡群和14个阴性鸡群，在阳性群167份血清中161份滴度≥1:16，在阴性群648份血清中640份≤1:4。对阴性群数据进行统计学处理。并根据正态分布规律。将阳性标准定为≥1:16。     

NaCl胁迫对花菖蒲叶片生长及几种生理指标的影响

[目的]探讨花菖蒲的抗盐能力。[方法]以取自江苏省宜兴苗圃的花菖蒲为材料,土壤盐化处理设5个盐度水平(0、0.2%、0.4%、0.6%、0.8%),采用盆栽法,研究不同NaCl胁迫强度条件下花菖蒲的生长及生理生化指标的变化情况。[结果]随着NaCl胁迫强度的增加,花菖蒲的叶片有不同程度的干枯、发黄、失绿、生长势衰退等现象。丙二醛含量、游离脯氨酸含量和SOD活性均随胁迫强度的增大和胁迫时间的延长而整体表现为上升的趋势,叶绿素含量随胁迫强度和胁迫时间的延长呈不断降低的趋势。通过对外观形态的观测以及生理指标的分析,推断出花菖蒲的耐盐阈值是0.4%,存活阈值是0.8%。[结论]该研究为改良土壤、绿化水体、湿地和盐碱地景观的营建提供了科学依据。     

大豆蛋白用作水溶性防腐剂中铜的螯合剂的初步研究

大豆蛋白首次被引进于木材防腐处理作为铜的螯合剂。试验结果表明,经过硫酸铜、氨水和大豆蛋白ＨＭ９０处理西黄松（Ｐｉｎｕｓｐｏｎｄｅｒｏｓａ）边材,铜的流失有明显减少。在铜氨溶液中加入８和１６ｋｇ／ｍ３大豆蛋白ＨＭ９０,其处理木块经流失试验后的固着率平均分别为起始固着率的７５％和６６％,由于蛋白对铜的螯合作用,流失处理后的固着率平均增加４０％,最高可达６２％。采用较低浓度的硫酸铜（１６ｋｇ／ｍ３）,流失处理后的固着率增长幅度达到最大值。但是,用铜蛋白处理的木块对褐腐菌（Ｐｏｓｔｉａｐｌａｃｅｎｔａ）的防腐效果没有明显提高,有待进一步的改进。     

Hip dysplasia in Estrela mountain dogs: prevalence and genetic trends 1991-2005

Three hundred and thirteen Estrela mountain dogs were examined for hip dysplasia (HD) using the standard ventrodorsal hip extended view, and graded into five categories (A, B, C, D and E) using the Fédération Cynologique Internationale’s (FCI) scoring system. The Ortolani method was performed to evaluate hip joint laxity. Pedigree information was obtained from the Portuguese Kennel Club and the genetic trend was evaluated by calculating the mean breeding values (BVs) for the last 15 years, using the threshold model.HD was found in 66% of the dogs. There was low-moderate correlation between the results of the Ortolani test and FCI hip scores (r_s = 0.386; P < 0.001). Grades of hip dysplasia were equal in both males and females (P = 0.14) and in the animals’ right and left sides (P = 0.51). The mean BVs for HD were stable in dogs born between 1991 and 2003, and showed an improvement in 2004 and 2005. The data confirm the high prevalence and severity of HD in predisposed breeds that do not have breeding programmes in place. It also confirms an initial favourable change in BVs that is a likely consequence of the voluntary radiographic hip-screening programme.     

Effects of Aging on Inner Ear Morphology in Dogs in Relation to Brainstem Responses to Toneburst Auditory Stimuli

Background: Age-related hearing loss (ARHL) is the most common form of hearing loss in humans and is increasingly recognized in dogs.
Hypothesis: Cochlear lesions in dogs with ARHL are similar to those in humans and the severity of the histological changes is reflected in tone audiograms.
Animals: Ten geriatric dogs (mean age: 12.7 years) and three 9-month-old dogs serving as controls for histological analysis.
Methods: Observational study. Auditory thresholds were determined by recording brainstem responses (BERA) to toneburst auditory stimuli (1, 2, 4, 8, 12, 16, 24, and 32 kHz). After euthanasia and perfusion fixation, the temporal bones were harvested and processed for histological examination of the cochleas. The numbers of outer hair cells (OHCs) and inner hair cells (IHCs) were counted and the spiral ganglion cell (SGC) packing density and stria vascularis cross-sectional area (SVCA) were determined.
Results: A combination of cochlear lesions was found in all geriatric dogs. There were significant reductions ( P .001) in OHC (42%, 95% confidence interval [CI]; 24–64%) and IHC counts (21%, 95% CI; 62–90%) and SGC packing densities (323, 95% CI; 216–290) in the basal turn, SVCA was smaller in all turns. The greatest reduction in auditory sensitivity was at 8–32 kHz.
Conclusions and Clinical Importance: ARHL in this specific population of geriatric dogs was comparable histologically to the mixed type of ARHL in humans. The predominance of histological changes in the basal cochlear turn was consistent with the large threshold shifts observed in the middle- to high-frequency region.     

土壤、水稻籽粒镉含量相关性分析及水稻产地土壤镉临界值的研究

在全国采集8个水稻产区、不同镉(Cd)含量的水稻土,添加0~4 mg/kg外源Cd,通过盆栽试验,分析水稻土、水稻籽粒Cd含量间的相关性,基于水稻籽粒Cd含量符合食品安全国家标准污染物限值(GB 2762–2012)的前提,确定8个水稻产地土壤的Cd临界值。结果表明:水稻土中Cd含量为0.20~6.27 mg/kg时,随土壤Cd浓度增加,水稻生长没有出现Cd毒害症状。籽粒Cd含量随水稻土Cd浓度的增加而增加,Logistic方程拟合表明籽粒Cd含量和水稻土Cd浓度间相关性显著;依据食品安全国家标准中稻米Cd限量值(0.2 mg/kg),反推得到8种水稻土Cd临界值范围为0.70~4.79 mg/kg,与现行土壤环境质量标准(GB15618–1995)相比,均高于其相应限值(0.3 mg/kg、pH≤7.5,0.6 mg/kg、pH7.5);对土壤理化性质和水稻土Cd临界值间关系进行多元回归分析,发现水稻土Cd临界值与pH和土壤黏粒显著相关(R2=0.83,P0.01)。     

基于SRTM DEM的大凌河流域地表水文自动模拟

[目的]基于SRTM DEM,对大凌河流域地表水文进行自动模拟。[方法]以大凌河流域SRTM DEM数据为支撑,在ArcGIS Model-Builder环境下构建大凌河流域地表水文模拟模型。[结果]地表水文模拟模型实现了大凌河流域范围的自动划分和大凌河流域水系的自动提取。同时,也更加便捷地解决了水文模拟中DEM填洼阈值和河网提取阈值的选择问题。大凌河流域范围划分准确,大凌河和相应Ⅰ级支流的提取结果与实际水文情况十分接近,但旁系小支流末梢的提取效果有待改进。[结论]该研究为今后地表水文的模拟提供了科学参考。     

Two measures of landscape-graph connectivity: assessment across gradients in area and configuration

Landscape connectivity is critical to species persistence in the face of habitat loss and fragmentation. Graph theory is a well-defined method for quantifying connectivity that has tremendous potential for ecology, but its application has been limited to a small number of conservation scenarios, each with a fixed proportion of habitat. Because it is important to distinguish changes in habitat configuration from changes in habitat area in assessing the potential impacts of fragmentation, we investigated two metrics that measure these different influences on connectivity. The first metric, graph diameter, has been advocated as a useful measure of habitat configuration. We propose a second area-based metric that combines information on the amount of connected habitat and the amount of habitat in the largest patch. We calculated each metric across gradients in habitat area and configuration using multifractal neutral landscapes. The results identify critical connectivity thresholds as a function of the level of fragmentation and a parallel is drawn between the behavior of graph theory metrics and those of percolation theory. The combination of the two metrics provides a means for targeting sites most at risk of suffering low potential connectivity as a result of habitat fragmentation.     

Effects of stream map resolution on measures of riparian buffer distribution and nutrient retention potential

Riparian ecosystems are interfaces between aquatic and terrestrial environments recognized for their nutrient interception potential in agricultural landscapes. Stream network maps from a broad range of map resolutions have been employed in watershed studies of riparian areas. However, map resolution may affect important attributes of riparian buffers, such as the connectivity between source lands and small stream channels missing in coarse resolution maps. We sought to understand the influence of changing stream map resolution on measures of the river network, near-stream land cover, and riparian metrics. Our objectives were: (1) to evaluate the influence of stream map resolution on measures of the stream network, the character and extent of near-stream zones, and riparian metrics; (2) to compare patterns of variation among different physiographic provinces; and (3) to explore how predictions of nutrient retention potential might be affected by the resolution of a stream map. We found that using fine resolution stream maps significantly increased our estimates of stream order, drainage density, and the proportion of watershed area occurring near a stream. Increasing stream map resolution reduced the mean distance to source areas as well as mean buffer width and increased the frequency of buffer gaps. Measures of percent land cover within 100 m of streams were less sensitive to stream map resolution. Overall, increasing stream map resolution led to reduced estimates of nutrient retention potential in riparian buffers. In some watersheds, switching from a coarse resolution to a fine resolution stream map completely changed our perception of a stream network from well buffered to largely unbuffered. Because previous, broad-scale analyses of riparian buffers used coarse-resolution stream maps, those studies may have overestimated landscape-level buffer prevalence and effectiveness. We present a case study of three watersheds to demonstrate that interactions among stream map resolution and land cover patterns make a dramatic difference in the perceived ability of riparian buffers to ameliorate effects of agricultural activities across whole watersheds. Moreover, stream map resolution affects inferences about whether retention occurs in streams or riparian zones.     

Genetic study of individual preweaning mortality and birth weight in Large White piglets using threshold-linear models

Individual records from 49,788 Large White piglets were used to evaluate preweaning mortality and its relationship with birth weight (BW). Preweaning mortality included farrowing mortality (TM) was also divided into stillbirth (SB), early (EM), late (LM) and total (ELM) preweaning mortality. Farrowing mortality was also studied as a sow's trait as number of piglets born dead (NBD). Threshold-linear models were used via MCMC. Traits included (1) TM-BW, (2) SB-ELM-BW, (3) SB-EM-LM and (4) NBD-ELM-BW. Model for BW included parity number, litter size, sex, contemporary group (farm-farrowing year-month), litter, and direct and maternal additive genetic effects. For mortality traits, litter effect was of the nursing litter for cross-fostered piglets (4.9%). Models for SB (2, 3) and NBD (4) excluded the effect of sex. In Model 3, BW was fitted as covariable for EM and LM. Estimates of direct and maternal heritability for BW were 0.03–0.06 and 0.14–0.19; and for mortality traits 0.03–0.12 and 0.08–0.12. Direct-maternal correlations were negative for all traits. Genetic correlations between all mortality traits were positive. Results confirmed the importance of BW for the genetic evaluation of piglet mortality. Early mortality is a good candidate for improvement of TM because of larger heritability and high genetic correlations with other mortality traits. It is most efficient to treat SB at sow level and preweaning mortality at the piglet level.