Nitrogen and energy loss in the marine teleost Lithognathus mormyrus (Linnaeus)

Nitrogen excretion and assimilation efficiencies in Lithognathus mormyrus (Linnaeus), a marine teleost present in high-energy surf zones in Algoa Bay, South Africa, were determined under controlled laboratory conditions at 15, 20 and 25 °C. Ammonia was the major form of nonfaecal nitrogen excreted by starved and fed L. mormyrus. Urea and amino acids were secondary excretory products. Ammonia excretion rates were temperature independent and the excretion rates of fed fish were significantly higher than starved fish at 20 and 25 °C but not at 15 °C. The mass component (b) of the mass/ammonia excretion equation was temperature independent and ranged from 0.590 to 0.669 and from 0.670 to 0.767 for starved and fed fish, respectively. The mean percentage of food energy lost via the dissolved nonfaecal excretory products (exogenous plus endogenous) was 4.12%. Assimilation efficiencies ranged from 71.89 to 98.78% for dry matter and from 96.89 to 99.88% on an energy basis. The combined nonfaecal and faecal energy loss was calculated at 10.11% of the ingested energy. The omnivorous ichthyofauna present in the surf zone ecosystem recycle 33 g N · m strip · yr⁻¹. This constitutes < 1 % of total phytoplankton nitrogen requirements.     

Predation on mammals by chimpanzees in the montane forest of Kahuzi, Zaire

The rate of predation on mammals by chimpanzees was determined from carcasses and from fecal specimens found on fresh trails during a 16-month period in the montane forest of Kahuzi-Biega National Park, Zaire. A unit-group of semi-habituated chimpanzees, composed of 22 – 23 individuals including 8 adult or adolescent males, appeared to kill about 18 – 30 mammalian prey (16 – 28Cercopithecus monkeys) per year, if the multiple kills by chimpanzees were not considered. A juvenile l'Hoest's monkey was recorded for the first time as the prey of chimpanzees in this study. Predation occurred in the late dry and the early rainy seasons, when the diversity of ripe fruits was the highest during the year. The Kahuzi chimpanzees tended to kill mammals less frequently but to killCercopithecus monkeys more frequently than chimpanzees in other habitats. The absence of red colobus monkeys, which are the most frequent prey in Gombe, Mahale, and Tai, might be responsible for the low predation rate. However, the estimated rate of predation onCercopithecus monkeys is the highest record among various chimpanzee habitats. At least 11 – 18% of theCercopithecus population seemed to be lost annually as a result of being killed by chimpanzees. Chimpanzees may be the most important predators on these monkeys in the absence of leopards at Kahuzi. The examination of fecal samples and carcasses suggested that adult (probably male) or adolescent chimpanzees tended to eat juvenile or subadult monkeys most frequently, as is also seen for chimpanzees in Gombe, Mahale, and Tai.     

Low accuracy of identifying Neotropical deer species by scat morphology

Morphometric feces data are used to identify ungulates, but their effectiveness is questioned by numerous authors. Herein, we evaluated the efficiency of this tool in discriminating scat samples from Neotropical deer with sympatric distributions. We performed discriminant analysis of previously identified scat samples (n = 204). The accuracy of discriminant analysis (56–92%) was lower than the confidence limit established in this study in all sympatric combinations expected in these biomes. These results demonstrate serious limitations regarding the use of scat morphometry for species identification of Neotropical deer and reinforce the need to use non-invasive genetic techniques.     

贮存温度和时间对大熊猫粪便样品皮质醇浓度的影响

通过非损伤性取样比如粪便样品监测野生动物受胁迫的水平已成为一个重要的手段,然而针对从野外采集的样品,其运输和贮存温度条件是否干扰分析结果,尚未有过报道。为评估不同贮存温度和天数对野生动物粪便样品中皮质醇浓度的影响,我们将大熊猫的新鲜粪便置于3 种模拟条件(0℃ 、10℃ 和22℃ ),并进行连续6 d的检测分析。结果表明,贮存天数对粪样中皮质醇浓度有显著影响(F _5,107 = 7.501,P = 0.001),但温度则无显著影响(F _2,107 = 1.094,P = 0.366)。粪样在0℃ 、10℃ 和22℃ 条件下贮存6 d,皮质醇浓度与贮存前的基准值之间均不存在显著差异(0℃ :F _6,41 = 1.274,P = 0.290;10℃ :F _6,41 = 2.027,P = 0.084;22℃ :F _6,41 =1.009, P = 0.434)。结果提示在室温条件下短期运输和贮存(不超过6 d),不会引起大熊猫粪便样品中皮质醇浓度的显著变化。该结果对于野外所采集的粪便样品运输和贮存具有一定的指导意义。     

Focused grooming networks and stress alleviation in wild female baboons

We examine the relationship between glucocorticoid (GC) levels and grooming behavior in wild female baboons during a period of instability in the alpha male rank position. All females' GC levels rose significantly at the onset of the unstable period, though levels in females who were at lower risk of infanticide began to decrease sooner in the following weeks. Three factors suggest that females relied on a focused grooming network as a coping mechanism to alleviate stress. First, all females' grooming networks became less diverse in the weeks following the initial upheaval. Second, females whose grooming had already focused on a few predictable partners showed a less dramatic rise in GC levels than females whose grooming network had been more diverse. Third, females who contracted their grooming network the most experienced a greater decrease in GC levels in the following week. We conclude that close bonds with a few preferred partners allow female baboons to alleviate the stress associated with social instability.     

Testing the threat-sensitive predator avoidance hypothesis: physiological responses and predator pressure in wild rabbits

Predation is a strong selective force with both direct and indirect effects on an animal’s fitness. In order to increase the chances of survival, animals have developed different antipredator strategies. However, these strategies have associated costs, so animals should assess their actual risk of predation and shape their antipredator effort accordingly. Under a stressful situation, such as the presence of predators, animals display a physiological stress response that might be proportional to the risk perceived. We tested this hypothesis in wild European rabbits (Oryctolagus cuniculus), subjected to different predator pressures, in Doñana National Park (Spain). We measured the concentrations of fecal corticosterone metabolites (FCM) in 20 rabbit populations. By means of track censuses we obtained indexes of mammalian predator presence for each rabbit population. Other factors that could modify the physiological stress response, such as breeding status, food availability and rabbit density, were also considered. Model selection based on information theory showed that predator pressure was the main factor triggering the glucocorticoid release and that the physiological stress response was positively correlated with the indexes of the presence of mammalian carnivore predators. Other factors, such as food availability and density of rabbits, were considerably less important. We conclude that rabbits are able to assess their actual risk of predation and show a threat-sensitive physiological response.     

Detection and persistence of fecal Bacteroidales as water quality indicators in unchlorinated drinking water

The results of this study support the use of fecal Bacteroidales qPCR as a rapid method to complement traditional, culture-dependent, water quality indicators in systems where drinking water is supplied without chlorination or other forms of disinfection. A SYBR-green based, quantitative PCR assay was developed to determine the concentration of fecal Bacteroidales 16S rRNA gene copies. The persistence of a Bacteroides vulgatus pure culture and fecal Bacteroidales from a wastewater inoculum was determined in unchlorinated drinking water at 10 °C. B. vulgatus 16S rRNA gene copies persisted throughout the experimental period (200 days) in sterile drinking water but decayed faster in natural drinking water, indicating that the natural microbiota accelerated decay. In a simulated fecal contamination of unchlorinated drinking water, the decay of fecal Bacteroidales 16S rRNA gene copies was considerably faster than the pure culture but similar to that of Escherichia coli from the same wastewater inoculum.     

Comparison of three microscopic techniques for diagnosis of Cyclospora cayetanensis

Cyclospora cayetanensis oocysts in the feces of humans from Kathmandu, Nepal were identified on the basis of their size and other morphological characteristics. We compared the detection of C. cayetanensis oocysts in the feces using three microscopic techniques such as formalin-ether sedimentation, sucrose centrifugal floatation, and direct smear. Standard procedures were used for the formalin-ether sedimentation and the sucrose centrifugal floatation techniques using 0.5 g of feces, however, the direct smear technique was performed using 10 microl of fecal suspension (0.005 g of feces) and observed under the fluorescent microscope. Of the 403 samples examined, 21 samples were positive for oocysts by all three techniques. Therefore, in these 21 samples, the number of oocysts recovered by the three techniques were compared. The highest number of oocyst was obtained by the sucrose centrifugal floatation technique. In contrast, the formalin-ether sedimentation technique was found to be the least reliable concentration technique for the detection of Cyclospora in human feces. Surprisingly, the direct smear technique was found to be an effective and rapid technique for diagnosis of C. cayetanensis making it a technique of choice for routine epidemiological investigation of the prevalence of this infection in human populations.     

水质微生物学检验实验模块的教学探索与实践

我校采用模块化教学形式开展水质微生物学检验实验教学。该模块由菌落总数测定、总大肠菌群测定及生理生化反应测试以及大肠菌群的血清学测试3个单元实验组成。实验内容以国家标准《生活饮用水标准检验方法——微生物指标(GB/T 5750.12-2006)》规定的程序进行编排。在教学过程中,注重模块实验的标准化操作,让学生树立标准化意识;通过连贯的模块化实验将卫生学检验实验转换为带有基础性的细菌分类学实验,在培养学生微生物学检验操作能力的同时,让学生系统地学习大肠杆菌的各种分类学鉴定方法。该模块的考核形式是学生参照专业机构的检验报告出具校园湖水的水质检验报告以及提交研究论文。水质微生物学检验实验模块的教学改革提高了学生的微生物数量研究能力和细菌分类研究能力,有利于学生开展创新型研究。