成体干细胞临床应用研究

干细胞是一类具有自我更新能力和多向分化潜能的细胞,其处于未定向分化状态并具有增殖能力.成体干细胞多向分化潜能,安全性好而在临床应用报道逐渐增多,本文总结了1998-2008年的成体干细胞临床应用的实例报道,以期为临床科研人员和患者提供信息支持.     

Physical and chemical cues affect oviposition by Neoleucinodes elegantalis

Recognition and acceptance of a suitable host plant by phytophagous insects requires the integration of visual, physical and chemical cues. The present study investigates the host cues that a specialist insect integrates to optimize oviposition decisions and whether these cues are weighted in a specific way. The study also determines whether the tomato fruit borer Neoleucinodes elegantalis (Guenée) (Lepidoptera: Crambidae), an important pest on Solanaceae in Brazil, shows a preference for oviposition sites that differ in physical and/or chemical cues. When styrofoam balls are provided as artificial fruits, N. elegantalis deposit significantly more eggs on rough artificial fruits than on smooth ones. Hexane fruit extracts applied to the artificial fruits stimulate female oviposition strongly. Physical and chemical cues also affect the oviposition of females when offered together. Furthermore, certain parts of the artificial fruits are prefered, irrespective of the presence of chemical cues. Both physical and chemical cues affect oviposition decisions; hence, the fruit borer relies on cues of different sensory modalities.     

Use of an individual-based model to forecast the effect of climate change on the dynamics, abundance and geographical range of the pest slug Deroceras reticulatum in the UK

Slugs are serious agricultural pests and their activity is strongly driven by ambient temperature and soil moisture. The strength of this relationship has been shown through the development of a deterministic model, based upon temperature and soil moisture conditions alone, which accurately describes the population dynamics and abundance of Deroceras reticulatum . Because of this strong climatic dependence, slug abundance and dynamics are likely to be affected by climate change. We used a validated individual-based model (IbM) of D. reticulatum , to assess the effects of climate change on the abundance of this species in the UK. Climatic scenarios were based on the UKCIP02 predictions and constructed using the LARS-WG stochastic weather generator. The IbM of slugs predicted population dynamics at three time slices (2020s, 2050s and 2080s), and two scenarios of greenhouse gas emissions. The maximum generation number, the number of population peaks, the number of slug-days in each season, the percentage of years when the population passes over a threshold for damage and the percentage of years in which populations go extinct were investigated. Currently, the south-west of the UK has the best conditions for D. reticulatum to thrive, with the north-east of Scotland having the most adverse. By 2080 under both low- and high-emissions scenarios, the north and west of Scotland will have the most favourable conditions for the survival of this species and the east of the UK and Scotland will have the harshest. By 2080 the climate in the north-west of Scotland will become more like the current climate in south-east England, which explains the shift in the pattern of abundance. The north-west of Scotland will have increased slug damage and south-west England and west-Wales will have decreased slug damage with some changes becoming evident by 2020.     

Population structure of African buffalo inferred from mtDNA sequences and microsatellite loci: high variation but low differentiation

The African buffalo ( Syncerus caffer ) is widespread throughout sub-Saharan Africa and is found in most major vegetation types, wherever permanent sources of water are available, making it physically able to disperse through a wide range of habitats. Despite this, the buffalo has been assumed to be strongly philopatric and to form large aggregations that remain within separate home ranges with little interchange between units, but the level of differentiation within the species is unknown. Genetic differences between populations were assessed using mitochondrial DNA (control region) sequence data and analysis of variation at six microsatellite loci among 11 localities in eastern and southern Africa. High levels of genetic variability were found, suggesting that reported severe population bottlenecks due to outbreak of rinderpest during the last century did not strongly reduce the genetic variability within the species. The high level of genetic variation within the species was found to be evenly distributed among populations and only at the continental level were we able to consistently detect significant differentiation, contrasting with the assumed philopatric behaviour of the buffalo. Results of mtDNA and microsatellite data were found to be congruent, disagreeing with the alleged male-biased dispersal. We propose that the observed pattern of the distribution of genetic variation between buffalo populations at the regional level can be caused by fragmentation of a previous panmictic population due to human activity, and at the continental level, reflects an effect of geographical distance between populations.     

Chemistry in Bioinformatics

 

Chemical information is now seen as critical for most areas of life sciences. But unlike Bioinformatics, where data is openly available and freely re-usable, most chemical information is closed and cannot be re-distributed without permission. This has led to a failure to adopt modern informatics and software techniques and therefore paucity of chemistry in bioinformatics. New technology, however, offers the hope of making chemical data (compounds and properties) free during the authoring process. We argue that the technology is already available; we require a collective agreement to enhance publication protocols.