海南尖峰岭自然保护区淡水龟类调查

2005年3~4月,采用野外调查和访问调查结合的方法,对尖峰岭自然保护区淡水龟类进行了专项调查。在海拔300~1 000 m设5个研究样区,采用系统抽样法在样区内选取443个研究样点,用笼捕法进行调查。野外调查共发现淡水龟类3种11只,包括8只平胸龟(Platysternon megacephalum)、2只四眼斑水龟(Sacalia quadriocellata)和1只锯缘摄龟(Pyxidea mouhotii)。访问调查得知当地还有黄额闭壳龟(Cuora galbinifrons)、三线闭壳龟(C.trifasciata)、中华鳖(Pelodiscus sinensis)和山瑞鳖(Palea steindachneri)分布。研究表明,尖峰岭自然保护区淡水龟类至少有2科7种,约占海南淡水龟类总种数的60%,其中四眼斑水龟和锯缘摄龟为本次调查到的尖峰岭淡水龟的新记录,三线闭壳龟和山瑞鳖为访问新记录。保护区内淡水龟类种群密度非常低,人为捕猎对淡水龟类资源破坏严重,需要加强保护和管理。     

Akt-dependent Activation of mTORC1 Complex Involves Phosphorylation of mTOR (Mammalian Target of Rapamycin) by IκB Kinase α (IKKα)

The serine/threonine protein kinase Akt promotes cell survival, growth, and proliferation through phosphorylation of different downstream substrates. A key effector of Akt is the mammalian target of rapamycin (mTOR). Akt is known to stimulate mTORC1 activity through phosphorylation of tuberous sclerosis complex 2 (TSC2) and PRAS40, both negative regulators of mTOR activity. We previously reported that IκB kinase α (IKKα), a component of the kinase complex that leads to NF-κB activation, plays an important role in promoting mTORC1 activity downstream of activated Akt. Here, we demonstrate IKKα-dependent regulation of mTORC1 using multiple PTEN null cancer cell lines and an animal model with deletion of IKKα. Importantly, IKKα is shown to phosphorylate mTOR at serine 1415 in a manner dependent on Akt to promote mTORC1 activity. These results demonstrate that IKKα is an effector of Akt in promoting mTORC1 activity.     

Amino Acids Activate Mammalian Target of Rapamycin (mTOR) Complex 1 without Changing Rag GTPase Guanyl Nucleotide Charging

Activation of mammalian target of rapamycin complex 1 (mTORC1) by amino acids is mediated in part by the Rag GTPases, which bind the raptor subunit of mTORC1 in an amino acid-stimulated manner and promote mTORC1 interaction with Rheb-GTP, the immediate activator. Here we examine whether the ability of amino acids to regulate mTORC1 binding to Rag and mTORC1 activation is due to the regulation of Rag guanyl nucleotide charging. Rag heterodimers in vitro exhibit a very rapid, spontaneous exchange of guanyl nucleotides and an inability to hydrolyze GTP. Mutation of the Rag P-loop corresponding to Ras^Ser-17 abolishes guanyl nucleotide binding. Such a mutation in RagA or RagB inhibits, whereas in RagC or RagD it enhances, Rag heterodimer binding to mTORC1. The binding of wild-type and mutant Rag heterodimers to mTORC1 in vitro parallels that seen with transient expression, but binding to mTORC1 in vitro is entirely independent of Rag guanyl nucleotide charging. HeLa cells stably overexpressing wild-type or P-loop mutant RagC exhibit unaltered amino acid regulation of mTORC1. Despite amino acid-independent raptor binding to Rag, mTORC1 is inhibited by amino acid withdrawal as in parental cells. Rag heterodimers extracted from ³²P-labeled whole cells, or just from the pool associated with the lysosomal membrane, exhibit constitutive [³²P]GTP charging that is unaltered by amino acid withdrawal. Thus, amino acids promote mTORC1 activation without altering Rag GTP charging. Raptor binding to Rag, although necessary, is not sufficient for mTORC1 activation. Additional amino acid-dependent steps couple Rag-mTORC1 to Rheb-GTP.     

Osmotic stress regulates mammalian target of rapamycin (mTOR) complex 1 via c-Jun N-terminal Kinase (JNK)-mediated Raptor protein phosphorylation

mTOR complex 1 (mTORC1) is a multiprotein complex that integrates diverse signals including growth factors, nutrients, and stress to control cell growth. Raptor is an essential component of mTORC1 that functions to recruit specific substrates. Recently, Raptor was suggested to be a key target of regulation of mTORC1. Here, we show that Raptor is phosphorylated by JNK upon osmotic stress. We identified that osmotic stress induces the phosphorylation of Raptor at Ser-696, Thr-706, and Ser-863 using liquid chromatography-tandem mass spectrometry. We found that JNK is responsible for the phosphorylation. The inhibition of JNK abolishes the phosphorylation of Raptor induced by osmotic stress in cells. Furthermore, JNK physically associates with Raptor and phosphorylates Raptor in vitro, implying that JNK is responsible for the phosphorylation of Raptor. Finally, we found that osmotic stress activates mTORC1 kinase activity in a JNK-dependent manner. Our findings suggest that the molecular link between JNK and Raptor is a potential mechanism by which stress regulates the mTORC1 signaling pathway.     

Problems in the harvest of edible birds' nests in Sarawak and Sabah, Malaysian Borneo

Due to the value of their nests, there is great pressure on the populations of black-nest swiftlets (Collocalia maximus) and white-nest swiftlets (Collocalia fuciphagus) in the Malaysian provinces of Sarawak and Sabah. The problems are particularly acute at Gunung Mulu National Park, in spite of a complete ban on collection there, and at Niah National Park, where every participant in a complex collection and trading system has an incentive to take more nests than permitted. More successful harvest systems function in Sabah's Gomantong and Madai Caves. Recommendations for improved management of the nest harvest include addressing corruption, ensuring that local people with traditional rights to collect nests do not lose income to illegal immigrant labor and to traders, improving research and education about the swiftlets' behavior and ecology, and moving value-added processing of the nests closer to the caves where they originate and to the people who collect them.     

Rhinoceros accounting in Kruger National Park,South Africa

Trends in rhinoceroses (rhinos) in Kruger National Park (Kruger) is of key concern. Poaching drives trends in the Park. Reconciling annual population estimates with yearly reports of poached carcasses fuels public critique. We account for trends in rhinos by extracting time series of estimates. Progressively modelling influences of management introductions and removals, effects of environmental variation and rhino density, direct impacts of poaching, consequences of imperfect carcass detection, and indirect impacts of deaths of dependent calves form the basis of accounting for rhinos. Models that considered all these influences explained 93% of white and 83% of black rhino population trends. In addition, the models predicted 2,515 white and 225 black rhinos, similar to estimates of 2,607 (95% CI: 2,475–2,752) and 202 (95% CI: 172–237) during 2020 respectively. The best model, however, predicts slow recovery with a white rhino population equivalent to pre-poaching achieved between 2030 and 2040. For black rhinos, recovery to pre-poaching population size would be between 2040 and 2050. The poaching onslaught in Kruger disrupted eruptive white rhino dynamics and prevented black rhinos from transitioning into eruptive dynamics. Authorities require innovative approaches within and beyond Kruger to help re-ignite rhino conservation.     

Combining limnological and palaeolimnological approaches in assessing degradation of Lake Pskov

Historical spawning grounds for sea lampreys (Petromyzon marinus L.) in most Portuguese river basins are becoming inaccessible due to the construction of impassable dams and/or weirs. Studies like the one described in this paper are particularly important in areas like the Vouga river basin, where there is a considerable fishing effort from both professional fishermen and poachers. In fact, for management and conservation purposes, it is important to clarify several aspects of the sea lamprey spawning run in this particular watershed. Therefore, a total of 30 radio tagged, migrating sea lampreys were released in the River Vouga and some of its main tributaries during 2004 and 2005. Results from the tracking sessions were used to determine the effect of poaching on the spawners’ population and the characteristics of the resting sites used during the upstream movement. The rivers’ stretches were also characterized according to the type of substrate present in the riverbed and flow type, in order to determine its aptitude to constitute appropriate spawning habitats for sea lampreys. We have identified in the upstream stretches of River Vouga, and in the tributary River Caima, characteristics that are particularly suitable for the construction of nests by the spawners. Presence of larvae provided evidence that spawners migrated into the River Vouga’s upper reaches. However, abundance and age class diversity appeared to be higher downstream of Sernada and Carvoeiro weirs, corroborating the telemetry data which suggested difficulty in passing these obstacles during low precipitation years. In the River Caima, migration was most predictable, which might be related to daily water releases from a small hydropower dam at dusk, that stimulated the lampreys to resume migration. Poaching has had a considerable negative effect on the success of the tagged lampreys’ migration: 76% of the animals released during 2005 were captured. Electronic supplementary material  Supplementary material is available for this article at and accessible for authorized user     

Optimising investments from elephant tourist revenues in the Maputo Elephant Reserve, Mozambique

Private enterprises are active in conservation initiatives in Africa. Some of these enterprises have long-term licences for the development of conservation areas. The motivation of these organisations to participate in conservation is ultimately determined by the economic output of their activities. An electric fence is being constructed in the Maputo Elephant Reserve, Mozambique. A costs-benefit analysis was carried out, in order to assist in the optimisation of the management activities of the elephant population, based on elephant population size, fence costs, crop raid costs, elephant poaching, and benefits derived from tourism (game-viewing and hunting). Tourist numbers increased with increasing elephant density through a concave utility function. Optimal harvest/hunting strategies were calculated from optimal control theory, using dynamic optimisation (Pontryagin's Maximum Principle). Poaching and raid costs could be compared to fence construction costs at different elephant population sizes. Costs generated through elephant poaching and elephant crop raid costs were higher than fence construction costs at a population size >100. Elephant hunting was a less favourable activity, economically and ecologically, than elephant viewing, due to the large game-viewing profits per elephant. Only if the licence fee increases from US$6500 to 28,500 would hunting become attractive, although ecological and economical constraints would probably prevent the development of hunting activities in the area. The assumed resource price of elephant (US$5000) was lower than the marginal value derived from tourism, indicating that elephants should be bought until the maximum stocking rate is reached.     

Effects of poaching on bull mating success in a free ranging African elephant (Loxodonta africana) population in Tarangire National Park, Tanzania

Poaching and habitat encroachment for human settlement are the two major factors that caused contraction of elephant populations in Africa. While the effects of poaching on many aspects of elephant social systems have been studied, the impacts on mating patterns are not yet understood and such information is still lacking in most African countries. In this study, we used elephant specific-microsatellite DNA to generate genotypes from 86 elephant samples (84 fresh faeces and two tissue samples) from Tarangire National Park (TNP), Tanzania to assess the mating success of individual males. We also tested whether the oldest bulls are more likely to sire most of the offspring in a severely poached population. Genetic paternity analysis was compared to behavioural observations of matings collected over a 3-year period (1998–2001) to determine the success of bull mating strategy. The genotypes of 26 infants, their known mothers and 10 out of 43 potential breeding bulls in TNP were used to assign 31% of the offspring at 80% confidence level to their potential fathers with simulation assuming that 23% (10/43) of the breeding males were sampled. Mating success of individual bull based on both behavioural and genetic data showed that the oldest remaining bulls performed most of the matings and fathered the majority of infants. We speculate that the lifetime fitness of bulls that have survived poaching may be elevated because their period of dominance increases.     

Do nomadic avian predators synchronize population fluctuations of small mammals? a field experiment

Three-to-five-year population oscillations of northern small rodents are usually synchronous over hundreds of square kilometers. This regional synchrony could be due to similarity in climatic factors, or due to nomadic predators reducing the patches of high prey density close to the average density of a larger area. We estimated avian predator and small rodent densities in 4–5 predator reduction and 4–5 control areas (c. 3 km² each) during 1989–1992 in western Finland. We studied whether nomadic avian predators concentrate at high prey density areas, and whether this decreases spatial variation in prey density. The yearly mean number of avian predator breeding territories was 0.2–1.0 in reduction areas and 3.0–8.2 in control areas. Hunting birds of prey concentrated in high prey density areas after their breeding season (August), but not necessarily during the breeding season (April to June), when they were constrained to hunt in vicinity of the nest. The experimental reduction of breeding avian predators increased variation in prey density among areas but not within areas. The difference in variation between raptor reduction and control areas was largest in the late breeding season of birds of prey, and decreased rapidly after the breeding season. These results appeared to support the hypothesis that the geographic synchrony of population cycles in small mammals may be driven by nomadic predators concentrating in high prey density areas. Predation and climatic factors apparently are complementary, rather than exclusive, factors in contributing to the synchrony.