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51.
Culture has long been assumed to be uniquely human but recent studies, in particular on great apes, have suggested that cultures also occur in non-human primates. The most apparent cultural behaviours in great apes involve tools in the subsistence context where they are clearly functional to obtain valued food. On the other hand, tool-use to modify acoustic communication has been reported only once and its function has not been investigated. Thus, the question whether this is an adaptive behaviour remains open, even though evidence indicates that it is socially transmitted (i.e. cultural). Here we report on wild orang-utans using tools to modulate the maximum frequency of one of their sounds, the kiss squeak, emitted in distress. In this variant, orang-utans strip leaves off a twig and hold them to their mouth while producing a kiss squeak. Using leaves as a tool lowers the frequency of the call compared to a kiss squeak without leaves or with only a hand to the mouth. If the lowering of the maximum frequency functions in orang-utans as it does in other animals, two predictions follow: (i) kiss squeak frequency is related to body size and (ii) the use of leaves will occur in situations of most acute danger. Supporting these predictions, kiss squeaks without tools decreased with body size and kiss squeaks with leaves were only emitted by highly distressed individuals. Moreover, we found indications that the calls were under volitional control. This finding is significant for at least two reasons. First, although few animal species are known to deceptively lower the maximum frequency of their calls to exaggerate their perceived size to the listener (e.g. vocal tract elongation in male deer) it has never been reported that animals may use tools to achieve this, or that they are primates. Second, it shows that the orang-utan culture extends into the communicative domain, thus challenging the traditional assumption that primate calling behaviour is overall purely emotional.  相似文献   
52.

Background

The lack of guidelines on reporting standards for protein electrophoresis may have led to significant differences in reports from different laboratories.

Objective

To determine the extent of variation in reporting of protein electrophoresis results in Australia and New Zealand.

Method

Questionnaires were distributed to laboratories throughout Australia and New Zealand asking about protein electrophoresis practices and reporting.

Results

Extensive variation was found in the following reporting practices: (a) units for urine Bence Jones protein (BJP); (b) reporting absence of a paraprotein rather than a normal pattern; (c) numerical reporting of all protein fractions or only the paraprotein; (d) warning of possible inaccuracy in the serum immunoglobulin result of the paraprotein type; (e) co-migration of a paraprotein with a normal serum protein; (f) use of a confirmatory test when a known paraprotein is no longer detectable.

Conclusions

A working party should be established to make recommendations on the reporting of protein electrophoresis. Implementation of such recommendations should reduce both report variation between laboratories and the risk of misinterpretation of reports.  相似文献   
53.
1. The issue of freshwater species being threatened by invasion has become central in conservation biology because inland waters exhibit the highest species richness per unit area, but apparently have the highest extinctions rates on the planet. 2. In this article, we evaluated the effects of an exotic, invasive aquatic grass (Urochloa subquadripara– tropical signalgrass) on the diversity and assemblage composition of native macrophytes in four Neotropical water bodies (two reservoirs and two lakes). Species cover was assessed in quadrats, and plant biomass was measured in further quadrats, located in sites where tropical signalgrass dominated (D quadrats) and sites where it was not dominant or entirely absent (ND quadrats). The effects of tropical signalgrass on macrophyte species richness, Shannon diversity and number of macrophyte life forms (a surrogate of functional richness) were assessed through regressions, and composition was assessed with a DCA. The effects of tropical signalgrass biomass on the likelihood of occurrence of specific macrophyte life forms were assessed through logistic regression. 3. Tropical signalgrass had a negative effect on macrophyte richness and Shannon and functional diversity, and also influenced assemblage composition. Emergent, rooted with floating stems and rooted submersed species were negatively affected by tropical signalgrass, while the occurrence of free‐floating species was positively affected. 4. Our results suggest that competition with emergent species and reduction of underwater radiation, which reduces the number of submersed species, counteract facilitation of free‐floating species, contributing to a decrease in plant diversity. In addition, homogenisation of plant assemblages shows that tropical signalgrass reduces the beta diversity in the macrophyte community. 5. Although our results were obtained at fine spatial scales, they are cause for concern because macrophytes are an important part of freshwater diversity.  相似文献   
54.
目的对长爪沙鼠线粒体DNA控制区全序列进行测定,并对其进行鉴定及进化分析。方法根据长爪沙鼠已知基因序列设计引物,采用PCR产物测序法,对所得的片段进行测序鉴定。结合已公布啮齿类动物D-loop区序列,分析其碱基组成、遗传距离、并基于最小进化法和UPGMA法构建系统进化树。结果获得长爪沙鼠D-loop区序列,其与家鼠、小家鼠和仓鼠平均同源性为58%;碱基组成分析显示,长爪沙鼠与啮齿类动物有相似的碱基组成和碱基偏离,其A-skew和G-skew分别为0.0047和-0.28。进化分析结果显示,长爪沙鼠与家鼠(0.35)、黑家鼠(0.38)和仓鼠(0.39)具有较近的遗传距离,其分化顺序为跳鼠、蔗鼠、长爪沙鼠、仓鼠、家鼠和小家鼠。结论本研究获得长爪沙鼠D-loop区全序列,确定了长爪沙鼠与仓鼠、家鼠、小家鼠及其它啮齿动物的进化关系,为长爪沙鼠进化研究、线粒体的结构和功能研究奠定基础。  相似文献   
55.

Background

Bornean orangutans (Pongo pygmaeus) currently occur at low densities and seeing a wild one is a rare event. Compared to present low encounter rates of orangutans, it is striking how many orangutan each day historic collectors like Alfred Russel Wallace were able to shoot continuously over weeks or even months. Does that indicate that some 150 years ago encounter rates with orangutans, or their densities, were higher than now?

Methodology/Principal Findings

We test this hypothesis by quantifying encounter rates obtained from hunting accounts, museum collections, and recent field studies, and analysing whether there is a declining trend over time. Logistic regression analyses of our data support such a decline on Borneo between the mid-19th century and the present. Even when controlled for variation in the size of survey and hunting teams and the durations of expeditions, mean daily encounter rates appear to have declined about 6-fold in areas with little or no forest disturbance.

Conclusions/Significance

This finding has potential consequences for our understanding of orangutans, because it suggests that Bornean orangutans once occurred at higher densities. We explore potential explanations—habitat loss and degradation, hunting, and disease—and conclude that hunting fits the observed patterns best. This suggests that hunting has been underestimated as a key causal factor of orangutan density and distribution, and that species population declines have been more severe than previously estimated based on habitat loss only. Our findings may require us to rethink the biology of orangutans, with much of our ecological understanding possibly being based on field studies of animals living at lower densities than they did historically. Our approach of quantifying species encounter rates from historic data demonstrates that this method can yield valuable information about the ecology and population density of species in the past, providing new insight into species'' conservation needs.  相似文献   
56.

Background  

Hyperplasia of usual type (HUT) is a common proliferative lesion associated with a slight elevated risk for subsequent development of breast cancer. Cell cycle-related proteins would be helpful to determine the putative role of these markers in the process of mammary carcinogenesis. The aim of this study was to analyze the expression of cell cycle related proteins in HUT of breast specimens of patients with and without breast cancer, and compare this expression with areas of invasive carcinomas.  相似文献   
57.
58.
Molecular dynamics (MD) simulations were used to study the stability and solvation of amylose and cellulose fragments. The recently developed gromos carbohydrate force field was further tested by simulating maltose, cellobiose, and maltoheptaose. The MD simulations reproduced fairly well the favorable conformations of disaccharides defined by the torsional angles related with the glycosidic bond and the radius gyration of maltoheptaose. The effects of methylation at different hydroxyl groups on the stability of amylose and cellulose fragments were investigated. The methylations of O-2 and O-3 reduce the stability of a single helix more than methylation at O-6, while the latter reduces the stability of a double helix more. Solvation free-energy differences between the unsubstituted amylose and cellulose fragments and the methylated species were studied using the single-step perturbation method. It was found that methylation at O-2 has the biggest effect, in agreement with experiment.  相似文献   
59.
Food availability is one of the basic factors affecting primate density and socioecology, but food availability is difficult to assess. Two different ways to obtain accurate estimates of food availability have been proposed: using phenology data or using the behaviour of animals. Phenology data can be refined by only including trees that are large enough to be used; including (potential) tree species in which by the concerned primate species forage; or including (fruiting) trees of these species that actually produce fruit. Alternatively, the sizes of the actually visited trees (foraging trees) give an estimate of fruit availability. These measures are compared for three sympatric primate species at the Ketambe Research Station, Sumatra, Indonesia: the Thomas langur, the long-tailed macaque and the orangutan. The sizes of fruiting trees and the foraging trees are larger than the potential trees. The sizes of the potential trees and of the fruiting trees are similar for the three primate species. This, however, is not reflected in the use of trees: the langurs forage on average in trees of similar size to those producing fruit, whereas the macaques and orangutans forage in trees larger than those producing fruit. The use of trees does not necessitate a different cut off point of included dbhs for the three compared primate species. The use of trees of different sizes, however, may be regulated by food competition. This indicates that sympatric primates make different foraging decisions and that behavioural measures of food availability will be less reliable.  相似文献   
60.
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