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991.
This study deals with maturation and aging of the vertebrae in Japanese macaques (Macaca fuscata fuscata) of known chronological age. The samples used were 103 skeletons of captive raised Japanese macaques varying in age from 6-23 years. Epiphyseal union between the vertebral body and the epiphyseal disk (epiphyseal ring, annular epiphysis) and degenerative changes of the vertebrae were macroscopically examined. It was revealed that vertebral epiphyseal union develops comparatively rapidly in the sacral and cervical vertebrae, moderately in the lumbar vertebrae, and slowly in the thoracic vertebrae. It was found that, as a central tendency, the vertebral epiphyseal union begins at about 6 years of age, progresses lineally in proportion to age, and completes at about 23 years of age. However, considerable variation in developmental states of union was observed among individuals of the same age. Concerning vertebral degenerative changes, few were observed among the present samples. Compared with the other primates with regard to the timing of vertebral maturation, shortening of duration of maturation was found among humans. Human vertebrae may have become an early-maturing organ in order to sustain the increased loading that is accompanied by the adoption of habitual erect posture and bipedal locomotion.  相似文献   
992.
Banana is a major crop in the French West Indies, where it is subjected to strong parasite pressure, resulting in pesticide pollution. An increase in plant population diversity in the cultivated ecosystem is generated by changing cultural practices. This results in a decrease in parasite pressure and hence a decrease in pollutant pesticide loads. Agricultural sustainability is therefore reinforced for better coexistence of populated, cultivated and protected areas.  相似文献   
993.
Uberti D  Meli E  Memo M 《Amino acids》2002,23(1-3):27-30
Summary.  Previous work from our laboratory has suggested the functional contribution of p53 to the cascade of events triggered by excitatory amino acids and leading to cell death in primary neurons. Here we show that this paradigm can be extended to cortical neurons treated with NMDA. We found that exposure of the cells to either 300 μM or 2 mM NMDA induced an enhancement of p53 protein levels which was already significant at 60 min after the lesion, while very low staining of the protein was observed in untreated cells. The effect was time- and concentration-dependent, reaching the maximal induction at 3 h. NMDA treatment also resulted in an increase of gadd45 protein levels which was evident in both treatment at 3 h, the time when p53 was maximally induced. Our data give further evidence suggesting that a repertoire of events typical of proliferating cells is activated in degenerating neurons. Received June 29, 2001 Accepted August 6, 2001 Published online June 3, 2002  相似文献   
994.
森林退化/衰退的研究与实践   总被引:7,自引:3,他引:4  
森林退化可以理解为森林面积减少、结构丧失、质量降低、功能下降;森林衰退则是森林退化的一种形式,指森林(树木)在生长发育过程中出现的生理机能下降、生长发育滞缓、生产力降低甚至死亡,以及地力衰退等状态.国内外研究表明,森林采伐/毁林是造成森林面积减少的最主要原因,有关森林采伐/毁林引起的森林退化研究主要集中在森林退化的后果、国家/国际政策的影响、加强全球性合作以及寻求解决途径等方面.森林衰退原因可归纳为:工、农业污染,自然胁迫/致衰因子,林分动态发生变化,森林衰退病或生态病,人工纯林以及纯林连栽导致的地力、生产力衰退等.中国的森林退化/衰退现状与世界各地森林退化基本一致,但由于历史原因,中国森林退化又有其自身特点:近一个世纪的强烈人为干扰,使大部分原始天然林退化为次生林;中国拥有世界上最多的人工林,且多数人工林均具有质量差、功能低等衰退特征.本文在综述森林退化/衰退研究与实践基础上,提出中国现代森林退化/衰退的的主要原因,给出中国森林退化/衰退的基本对策.  相似文献   
995.
外生菌根真菌对科尔沁沙地樟子松人工林衰退的影响   总被引:3,自引:0,他引:3  
通过对科尔沁沙地东南缘樟子松人工林气温、地温及樟子松人工林根系分布的观测,从温度对外生菌根菌存活与生长影响的角度分析了沙地樟子松人工林衰退的现象,结果表明:由于沙地表层土壤(0~5cm)高温环境,外生菌根菌无法存活;在沙地20~40cm土层内,温度条件有利于外生菌根菌的存活、生长,而13~42年生沙地樟子松人工林树木平均78%的根系分布于该层,说明外生菌根菌的存在阻止或延缓了樟子松人工林的生长衰退,不是导致沙地樟子松人工林枯叶、枯梢、枯枝、死亡的原因.表层土壤外生菌根菌的缺乏使萌发的幼苗不能形成有效根系是导致沙地樟子松人工林不能天然更新的主要原因之一.  相似文献   
996.
1.  Yellowhammers began to decline on British lowland farmland in the late 1980s and losses are presently 10% per year. This study examined variation in the habitat selection and breeding success of yellowhammers, allowing an evaluation of whether Britain's yellowhammer decline might have been caused by recent changes in agriculture.
2.  Yellowhammer territories were associated with hedgerows, vegetated ditches and wide uncultivated grassy margins around fields. Pasture and silage leys were avoided. Nests were built among herbaceous vegetation in ditches or in the shrubby vegetation of hedgerows.
3.  Breeding started slightly earlier on organic farms than on intensively managed farms, but no measure of breeding success differed between farm types. Predation was the cause of most (64%) nest failures. A maximum of three breeding attempts (two successful) was observed per pair, with a mean clutch size of 3·3, a Mayfield nest success rate of 0·46, and 2·6 nestlings fledged per successful brood. These data, together with published estimates of adult yellowhammer survival and of post-fledging survival among other passerines, suggest that breeding productivity is too low to maintain a stable population.
4.  The removal of hedgerows or abandonment of hedge management, filling or clearing of ditches, intensification of grassland management and cropping or grazing right up to the field edge, are all likely to have adversely affected yellowhammers on lowland farmland in southern England. Policy reforms that redirect subsidy support to environmentally beneficial management of field margin habitats and retention of winter-feeding sites such as stubbles should assist in restoring populations of breeding yellowhammers on lowland farmland.
5.  Our data expand further the array of farmland bird species for which interactions between agricultural change and population change are increasingly understood.  相似文献   
997.
The Hippo pathway plays an important role in many pathophysiological processes, including cell proliferation and differentiation, cell death, cell migration and invasion. Because of its extensive functions, Hippo pathway is closely related to not only growth and development, but also many diseases, including inflammation and cancer. In this study, the role of Hippo pathway in craniofacial diseases and hard tissue remodeling was reviewed, in attempting to find new research directions.  相似文献   
998.
The life cycle of Vibrio parahaemolyticus has been conventionally associated with estuarine areas characterized by moderate salinity and warm seawater temperatures. Recent evidence suggests that the distribution and population dynamics of V. parahaemolyticus may be shaped by the existence of an oceanic transport of communities of this organism mediated by zooplankton. To evaluate this possibility, the presence of V. parahaemolyticus in the water column of offshore areas of Galicia was investigated by PCR monthly over an 18-month period. Analysis of zooplankton and seawater showed that the occurrence of V. parahaemolyticus in offshore areas was almost exclusively associated with zooplankton and was present in 80% of the samples. The influence of environmental factors assessed by generalized additive models revealed that the abundance and seasonality of V. parahaemolyticus in zooplankton was favoured by the concurrence of downwelling periods that promoted the zooplankton patchiness. These results confirm that offshore waters may be common habitats for V. parahaemolyticus, including strains with virulent traits. Additionally, genetically related populations were found in offshore zooplankton and in estuaries dispersed along 1500 km. This finding suggests that zooplankton may operate as a vehicle for oceanic dispersal of V. parahaemolyticus populations, connecting distant regions and habitats, and thereby producing impacts on the local community demography and the spread of Vibrio-related diseases.  相似文献   
999.
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Highlights
  • •Quantitative proteome interactions with 5 different C9ORF72 dipolypeptides (DPRs).
  • •The arg-rich DPRs promiscuously bound to the proteome compared with the other DPRs.
  • •Long repeat lengths of arg-rich DPRs, but not short lengths, stalled ribosomes.
  • •The arg-rich DPRs also reduced arginine methylation and actin cytoskeleton assembly.
  相似文献   
1000.
Immune checkpoint inhibitors (ICIs) and immunotherapy have proven to be a transformative therapy for many forms of cancer treatment. While many antibodies targeting the PD-1, PD-L1, and CTLA-4 pathways have been approved for clinical use by the FDA, it is clear that a single ICI is not sufficient to eradicate disease. ICI combination strategies are being extensively investigated to advance cancer treatment to next curative stage. Among the immune checkpoint inhibitors being actively investigated, the potential of VISTA (V-domain Ig suppressor of T cell activation), a unique B7 family member that functions as both ligand and receptor, is being actively pursued. This article summarizes the expression and immunomodulatory effects of VISTA in autoimmune diseases and cancer, and assesses its potential as an additional component of immune checkpoint cancer therapy.  相似文献   
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