宜黄自然保护区华南虎野生种群调查及栖息地评价

江西省宜黄县省级自然保护区以华南虎 (Pantheratigrisamoyensis)为主要保护对象 ,是近几年发现华南虎证据最多的区域 .中美华南虎联合考察队于 2 0 0 1年 3 7月对该保护区进行了调查 ,采用访问调查法、样线调查法、痕迹调查法、红外线自动照相技术等目前国际国内通用的方法和技术 .该次考察虽未证实该区域华南虎存在的确切信息 ,但较系统地调查了该区域的生境资料 ,初步评价了华南虎的生存环境 .其结论为 ,由于乱捕滥猎、过度的经济活动、栖息地缩小和破碎化是导致目前华南虎极度濒危甚至难觅其踪迹的主要原因 .该区域历史上是华南虎较多的区域 ,目前仍具备华南虎生存的基本条件 .     

Diurnal variation of spontaneous uterine activity in nonpregnant primates (Macaca mulatta)

Diurnal variations in the average intrauterine pressure and in the average frequency of contraction were demonstrated in four nonpregnant rhesus monkeys. Uterine activity is lowest between 0400 and 0700 hours and highest between 1400 and 1700 hours. There is statistically significant correlation between uterine activity and diurnal variation in core temperature.     

Ordered and dynamic assembly of single spliceosomes

The spliceosome is the complex macromolecular machine responsible for removing introns from precursors to messenger RNAs (pre-mRNAs). We combined yeast genetic engineering, chemical biology, and multiwavelength fluorescence microscopy to follow assembly of single spliceosomes in real time in whole-cell extracts. We find that individual spliceosomal subcomplexes associate with pre-mRNA sequentially via an ordered pathway to yield functional spliceosomes and that association of every subcomplex is reversible. Further, early subcomplex binding events do not fully commit a pre-mRNA to splicing; rather, commitment increases as assembly proceeds. These findings have important implications for the regulation of alternative splicing. This experimental strategy should prove widely useful for mechanistic analysis of other macromolecular machines in environments approaching the complexity of living cells.     

Grazing Management in Tropical Savannas: Utilization and Rest Strategies to Manipulate Rangeland Condition

Grazing management is important for sustaining the productivity and health of rangelands. However, the effects of grazing management on herbage growth and species composition in the tropical savannas of northern Australia are not well known. In this eight-year study the influences of utilization rate and resting pastures from grazing on vegetation dynamics were measured at three sites in northeast Queensland, Australia. The sites had high, medium, and low soil fertility, and there were two land condition classes (States I and II) at each site. Severe drought occurred during the first four years, but above-average rainfall was received in the second half of the study. High utilization rates reduced biomass, perennial grass basal area, and ground cover. The reduction in biomass was due to both higher consumption and decreased primary production. State I condition plots at the high and medium soil fertility sites were initially dominated by decreaser perennial grasses, but these declined at all utilization levels, particularly the high rate. They were largely replaced by exotic perennial grasses. At the low fertility site there were no exotic grasses, and the decreaser grasses increased in all treatments, with the increases greatest in plots with low utilization or medium utilization plus resting. In the State II condition plots at the high and medium fertility sites, low or moderate utilization, led to an increase in both decreaser and exotic perennial grasses; with high utilization the decreaser perennial grasses declined and were replaced largely by exotic perennial grasses. This study clearly demonstrated that either conservative stocking with year-round grazing or a grazing system that includes some wet-season resting will help maintain land in a desirable state or help facilitate the transition from a less desirable ecological state to one more desirable for pastoral production and rangeland condition.     

Systemic mucormycosis in a hooded seal (Cystophora cristata)

A 4-yr-old male captive hooded seal (Cystophora cristata), previously diagnosed as hypothyroid, died after a 3-wk period of lethargy and inappetance despite treatment that included intramuscular administration of antibiotics and multivitamins. Gross pathologic findings included extensive muscle necrosis over the left flank, an underlying necrotic iliac lymph node, two necrotic pulmonary masses and a necrotic bronchial lymph node. Routine cultures yielded a number of bacterial isolates and a heavy pure fungal growth from the necrotic iliac lymph node; wet preparations of which revealed sporangiophores typical of Mucor sp. Histopathology of necrotic muscle, pulmonary lesions and bronchial and iliac lymph nodes revealed necrosis with a marked pyogranulomatous and eosinophilic inflammatory cell infiltrate and fungal hyphae consistent with a Zygomycete species. This is believed to be the first report of systemic mucormycosis in a pinniped likely to have originated from an injection site reaction.     

An empirical approach to target DNA quantification in environmental samples using real-time polymerase chain reactions

Recent advances in molecular techniques have allowed for the routine examination of nucleic acids in environmental samples. Although current methodologies are very sensitive, accurate target DNA quantification from environmental samples remains challenging. To facilitate high-throughput DNA quantification from environmental samples, we developed a novel DNA quantification method based on a non-linear curve-fitting approach to extract additional information from quantitative PCR amplification curves and used the fitted parameters to develop multiple regression standard equations for target DNA quantification. A 3-parameter sigmoidal function performed superior to a 4-parameter Weibull function for generating the multiple regression standard equations. In a verification experiment, target DNA was quantified in a series of ‘unknown’ samples in three soils using this approach and the results were compared to target DNA values determined using corrected and uncorrected Ct-based (threshold cycle) methods. For each method, the deviations from the expected target DNA content were determined. Results clearly showed that over all DNA concentrations, target DNA content determined by the non-linear curve-fitting method was more accurate and more precise than values predicted by all other methods. Analysis of variance conducted on the predicted DNA contents also revealed fewer statistical artifacts with the non-linear curve fitting method compared to the conventional Ct-based methods. The novel approach described here is accurate, inexpensive, and very amenable for automation and high-throughput applications.     

Surplus killing by introduced predators in Australia—evidence for ineffective anti-predator adaptations in native prey species?

Australian examples of surplus killing by mammalian predators were collated. These included surplus killing of native mammals and birds by foxes (Vulpes vulpes) and stock, native mammals and native birds by dingoes (Canis lupus dingo). We found no examples of surplus killing by feral cats (Felis catus). Incidents collated include historical anecdotes of surplus killing by foxes as they colonised the Australian mainland, recent examples where foxes killed threatened native species at sites despite intensive management to exclude foxes, and recent examples of the killing of native species on formerly fox-free islands to which foxes gained entry. Episodes of surplus killings by foxes, other than predation on captive or closely confined animals, appeared different in kind and frequency to those documented for co-evolved predator-prey systems on the large continental landmasses. They did not appear to be uncommon events associated with synchronised births of prey species, unusual or extreme weather that disadvantaged prey species, or seasonal food caching by a predator. Rather, surplus killing events appeared to reflect ineffective anti-predator defences by prey species when encountering a novel and efficient predator to which they have had no evolutionary exposure. We suggest that surplus killing by foxes may have been a feature of, and major contributor to, the rapid mainland extinction or contraction in range of many native species in Australia. In contrast to foxes, examples of surplus killing by dingoes relate mostly to domestic stock (calves and sheep). The arrival of dingoes to the Australian continent preceded that of foxes by 3500-4000 years, but they appear not to have had the dire impact on native mammals that we attribute to foxes. This may be due to fundamental differences in hunting styles and prey size and to their sparse populations in pre-European Australia. Active persecution of non-commensal dingoes by Aborigines, the lack of free-water, and the absence of European rabbits (Oryctolagus cuniculus) as an alternative food supply would have limited their numbers and their impact on native mammals.     

Multi-element analysis of an english peat bog soil

Nineteen elements were quantitatively determined by atomic emission spectroscopy with inductively coupled plasma in peat profiles in Ringinglow Bog, Derbyshire, England. For the elements Ba, Ca, Cd, Co, Cr, Fe, La, Mn, Ni, Ti, and Zn an enrichment in the upper 5 cm of the peat bogs was found probably caused by anthropogenic influences. The elements Al, Be, Cu, and Pb showed a different distribution pattern with maximum concentration in the 5 to 15 cm layer. The elements Mg, Na, and Sr showed no enrichment in the upper 55 cm of the peat reflecting the constant input of these elements from the sea during the last few centuries. Upper parts (leaves and stems) of the plants investigated (Calluna vulgaris and Eriophorum vaginatum) only represent higher values of Pb compared with the normal element content in other plants. Compared with the results of peat profiles in a Norwegian bog, the concentrations of the comparable elements (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) are much higher in the English peat. Ringinglow Bog seem to be very suitable for further investigations within the scope of a global monitoring programme.