滇西亚种树鼩体外寄生虫自然感染状况及分析

目的调查滇西亚种树鼩体外寄生虫的自然感染状况,为建立树鼩质量控制标准提供依据。方法对野生的滇西亚种树鼩和自繁F1代树鼩各60只分别用尸检法和活体法检测,随即采用拔毛或用透明胶带粘取腋下、耳根、腹股沟、肛门附近等处的毛发制片,置于体视镜和显微镜下观察虫体和虫卵。结果野生滇西亚种树鼩和自繁F1代树鼩体外寄生虫自然感染率分别为：虱子25%/6%、蚤5%/0、蜱1.6%/0、水蛭1.6%/0、虱子和蚤混合感染1.6%/0。结论野生树鼩体外寄生虫的自然感染多为虱子和蚤,其次还有蝉、水蛭,总感染率明显高于自繁F1代。使用灭虱灵对于驱除树鼩体外寄生虫具有较好的疗效。     

牡丹PsCS基因的克隆及序列分析

以牡丹品种‘赵粉’(Paeonia suffruticosa L.cv.‘Zhao Fen’)为试材,采用RT-PCR和RACE方法从雄蕊中获得了一个牡丹柠檬酸合成醇(citrate synthase,CS)基因cDNA全长,命名为PsCS,GenBank登录号为HQ449568.其cDNA全长1 564 bp,包含75 bp的5’非编码区、73 bp的3 '非编码区和一个长度为1 416 bp编码471个氨基酸的开放阅读框.序列比对和系统进化分析表明,PsCS与葡萄的亲缘关系最近,相似性达89.4％以上.     

Tree dieback and regeneration in secondary Acacia zanzibarica woodlands on an abandoned cattle ranch in coastal Tanzania

Questions: Bush encroachment is a major problem when African savanna ecosystems are used for cattle ranching. How do secondary woodlands develop after ranching is abandoned? What are the patterns and rates of tree mortality and regeneration? Location: Mkwaja Ranch (now part of Saadani National Park) in coastal Tanzania. Methods: Ninety‐seven circular plots (4‐m radius) were set in secondary Acacia zanzibarica woodland along a gradient of tree density. Variables relating to tree and grass layers and soil characteristics of plots were recorded. Seedlings were counted twice in the wet seasons, and resprouts once. Tree flowering and pod production were assessed during the fruiting season, while survival of trees initially present was recorded after 12 and 32 months. Interrelationships among variables were investigated using multiple linear regression, binary logistic regression and mixed effects models. Results: After 32 months, over one‐third of trees in plots had died. Most died after fire, especially on heavy soils, and mortality was significantly related to the tree live biomass ratio and soil conditions. Seed production was very low, especially in denser stands. Numbers of seedlings correlated with soil and grass variables but not with seed rain. Half of trees killed above‐ground produced coppice shoots from the base; in contrast, root suckering was independent of topkill. By the end of the study, no seedlings survived and no resprouts emerged above the grass layer. Conclusions: A. zanzibarica woodlands at Mkwaja Ranch were able to develop because of ranching, and can only persist under intensive grazing. The woodlands do not represent a successional stage towards forest and will probably revert to predominantly grassland vegetation within 10–20 years unless grazing pressure from wild ungulates increases considerably and/or fire regimes change.     

Fire history of a prairie/forest boundary: more than 250 years of frequent fire in a North American tallgrass prairie

Questions: Most modern fire‐prone landscapes have experienced disruptions of their historic fire regimes. Are the primary tallgrass prairies of the Flint Hills reflective of a history of continuous fire occurrence? Did fire frequency, severity, size and seasonality change in connection with changes in land use? Has fire occurrence been related to drought conditions? Location: Edges of Cross Timbers forest stands at the Tallgrass Prairie Preserve (TGPP) in the Flint Hills of Osage County, Oklahoma, USA. Methods: Cross‐sections of 76 Quercus stellata were collected from Cross Timbers stands at or near the grassland edge in the TGPP. Dendrochronological methods were used to identify years of formation for tree rings and fire scars. Superposed epoch analysis was used to evaluate the effect of drought conditions on fire occurrence. Results: Fires were recorded in 46.6% of the years between 1729 and 2005. In 41 cross‐sections at one site, the mean fire interval between 1759 and 2003 was 2.59 years, with fire interval decreasing from a mean fire interval of 3.76 years in the early part of the record to 2.13 years in modern times. No extended periods without fire were recorded in the study area. Drought conditions had no significant effect on fire occurrence. Conclusions: In contrast with many fire‐prone landscapes worldwide, the prairies of the Flint Hills have experienced no recent fire suppression or exclusion. Changes in fire frequency mark transitions in land use, primarily from being traditionally used by Native Americans to being managed for cattle production.     

5-HT<Subscript>1A</Subscript> receptor expression in pyramidal neurons of cortical and limbic brain regions

We studied expression of the 5-HT_1A receptor in cortical and limbic areas of the brain of the tree shrew. In situ hybridization with a receptor-specific probe and immunocytochemistry with various antibodies was used to identify distinct neurons expressing the receptor. In vitro receptor autoradiography with ³H-8-OH-DPAT (³H-8-hydroxy-2-[di-n-propylamino]tetralin) was performed to visualize receptor-binding sites. In the prefrontal, insular, and occipital cortex, 5-HT_1A receptor mRNA was expressed in pyramidal neurons of layer 2, whereas ³H-8-OH-DPAT labeled layers 1 and 2 generating a columnar-like pattern in the prefrontal and occipital cortex. In the striate and ventral occipital cortex, receptor mRNA was present within layers 5 and 6 in pyramidal neurons and Meynert cells. Pyramid-like neurons in the claustrum and anterior olfactory nucleus also expressed the receptor. Principal neurons in hippocampal region CA1 expressed 5-HT_1A receptor mRNA, and ³H-8-OH-DPAT labeled both the stratum oriens and stratum radiatum. CA3 pyramidal neurons displayed low 5-HT_1A receptor expression, whereas granule neurons in the dentate gyrus revealed moderate expression of this receptor. In the amygdala, large pyramid-like neurons in the basal magnocellular nucleus strongly expressed the receptor. Immunocytochemistry with antibodies against parvalbumin, calbindin, and gamma aminobutyric acid (GABA) provided no evidence for 5-HT_1A receptor expression in GABAergic neurons in cortical and limbic brain areas. Our data agree with previous findings showing that the 5-HT_1A receptor mediates the modulation of glutamatergic neurons. Expression in the limbic and cortical areas suggested an involvement of 5-HT_1A receptors in emotional and cognitive processes.This work was supported by the German Science Foundation (SFB 406; C4 to G.F.).     

Immunocytochemical studies on translocation of phosphorylated aquaporin-h2 protein in granular cells of the frog urinary bladder before and after stimulation with vasotocin

We have generated a specific antibody against phosphorylated aquaporin-h2 (pAQP-h2) protein to investigate the role of phosphorylation in the translocation of AQP-h2 protein within the granule cells of the urinary bladder of the frog (Hyla japonica). The antibody was generated against a synthetic peptide (ST-160) corresponding to amino acids 255–268, with a phosphorylated Ser-262, a residue that is putatively phosphorylated by protein A kinase. Using this antibody, we found, by Western blot analysis, that phosphorylation of the AQP-h2 protein rapidly increased within 2 min after vasotocin (AVT) stimulation and remained at a higher than normal level for 15 min. Moreover, quantitative immunoelectron microscopy indicated that the location of the AQP-h2 protein dramatically changed after AVT stimulation. Before stimulation, pAQP-h2 protein was localized in only a small number of intracellular vesicles near the nucleus of the granular cells, whereas the labeling density of the intracellular vesicles and the apical membrane rapidly increased after stimulation. This finding was also confirmed by the results of an immunofluorescence study. Thus, phosphorylation of AQP-h2 protein seems to be essential for translocation of the protein from the cytoplasmic pool to the apical plasma membrane of the granular cells in frog urinary bladder. This work was supported in part by a grant-in-aid for scientific research from the Ministry of Education, Science, Sports, and Culture of Japan to S.T.     

Control of Nitrous Oxide Emissions in European Beech,Norway Spruce and Scots Pine Forests

Elevated nitrogen deposition has increased tree growth, the storage of soil organic matter, and nitrate leaching in many European forests, but little is known about the effect of tree species and nitrogen deposition on nitrous oxide emission. Here we report soil N₂O emission from European beech, Scots pine and Norway spruce forests in two study areas of Germany with distinct climate, N deposition and soils. N₂O emissions and throughfall input of nitrate and ammonium were measured biweekly during growing season and monthly during dormant season over a 28 months period. Annual N₂O emission rates ranged between 0.4 and 1.3 kg N ha^?1 year^?1 among the stands and were higher in 1998 than in 1999 due to higher precipitation during the growing season of 1998. A 2-way-ANOVA revealed that N₂O fluxes were significantly higher (p<0.001) at Solling than at Unterlüß while tree species had no effect on N₂O emissions. Soil texture and the amount of throughfall explained together 94% of the variance among the stands, indicating that increasing portions of silt and clay may promote the formation of N₂O in wet forest soils. Moreover, cumulative N₂O fluxes were significantly correlated (r² = 0.60, p<0.001) with cumulative NO ₃ ^? fluxes at 10 cm depth as an indicator of N saturation, however, the slope of the regression curve indicates a rather weak effect of NO ₃ ^? fluxes on N₂O emissions. N input by throughfall was not correlated with N₂O emissions and only 1.6–3.2% of N input was released as N₂O to the atmosphere. Our results suggest that elevated N inputs have little effect on N₂O emissions in beech, spruce and pine forests.     

The importance of microclimate variation in determining size,growth and survival of avian offspring: experimental evidence from a cavity nesting passerine

Organisms are expected to balance energy allocation in such a way that fitness is maximized. While much research has focussed on allocation strategies of reproducing parents, in particular birds, relatively little attention has been paid to how nestlings allocate energy while in the nest. Nestling birds are faced with a trade-off between devoting energy to growth or to thermoregulation, and in altricial species it is likely that the thermal environment of the nest site influences the nature of this trade-off. Here, we experimentally investigate how altering the microclimate of nests affects the growth, size and survival, as well as cell-mediated immune (CMI) response, of nestling tree swallows (Tachycineta bicolor) in a temperate environment. We place air-activated heating pads in nests of swallows when young were between 4 days and 16 days of age, and compared performance of offspring to control nests. Our manipulation raised temperatures of heated nests by approximately 5°C compared to control nests. Offspring in heated nests had enhanced survival while in the nest, and we also found that they were heavier and had longer ninth primary feathers at 16 days of age. In addition, heating nest boxes resulted in significantly faster growth of primaries, and there was a trend for growth rates of mass to also be higher in heated nests. There were no significant differences between heated and control nests in growth rate or size of tarsus at age 16 days, and we speculate that this lack of response to elevated nest temperatures may be due to growth of skeletal structures being limited by other factors such as calcium availability. We also found no difference between heated and control nests in CMI response. Nonetheless, our results show overall that increasing temperatures of nests has significant benefits that enhance the fitness of offspring. As provisioning rates to offspring did not differ between heated and control nests, we suspect that the beneficial effects of heating were not the consequence of changes in parental behaviour. Our results provide insight into factors, other than food supply, that have important consequences in determining reproductive success of birds breeding in temperate environments.     

Sapling growth and survivorship as affected by light and flooding in a river floodplain forest of southeast Texas

We investigated the effects of light and flooding on growth and survivorship of saplings in a river floodplain forest of southeast Texas. Growth responses to light were consistent with the expectation that shade-intolerant species grow faster than shade-tolerant species in high light, and vice versa. Mortality risk was not associated with shade tolerance level unless high mortality risks associated with a period of high flooding were removed. These results support the hypothesis that shade-tolerant species in floodplains may be limited by flooding as previous studies suggested. Also, compared to their performance at a nearby mesic site, common species showed little intraspecific difference in shade tolerance, especially for shade-intolerant species. Finally, the positive correlation between low-light growth and survivorship suggests that carbon allocation to continued growth may be favored as a sapling strategy in floodplains.     

秦岭川金丝猴冬季和春季在自然栖息地的空间利用

2000年9月到2003年3月共计197天的时间里,我们采用目标动物取样法(Focalanimalsampling)和行为的全事件记录法(Alloccurrencesampling)对一群生活在秦岭北坡周至保护区内的秦岭金丝猴(Rhinopithecusroxellana)在自然栖息地内空间利用的进行了研究。当猴群在离开人工投食区进行自由活动时我们开始收集数据。结果表明:秦岭川金丝猴在不同年龄性别组的个体对植被的空间利用明显不同,它们花费每天活动的14%的时间在地面上活动,53%时间在树叉处活动,33%的时间在树冠中间活动。与其它年龄性别个体相比,成年雄性有27%的观察时间在地上活动,并且20%的取食时间或29%的休息时间是在地上的,明显地高于其它年龄性别组的个体。群体迁移时,成年雄性有53%的时间在地上移动,而只有13%的时间是在树冠层移动的。在通过不同树冠的时候,成年雄性经常会同时抓住两边再把身体摆过去。它们也经常下到地上迁移而回避在树间跳跃。相比之下,亚成年雌性和青少年猴更加经常地在低植被层和树冠层中找食和休息。它们明显地比成年猴更加频繁地在树冠中移动,却很少下地。它们还经常使用跳跃的方式通过树冠间的空隙。从观察到摔下树的事例分析,青少年猴从树上摔下来的风险比成年猴大。本文进而讨论了影响秦岭金丝猴空间分布和移动的因素,比如说身体的重量等.