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Maternal uniparental disomy (UPD) 20 was found in a 35-month-old girl, the product of a pregnancy complicated by a prenatal diagnosis of mosaic trisomy 20. Phenotypic abnormalities included pre- and postnatal growth failure, microcephaly, minor dysmorphic features and psychomotor developmental delay. Chromosomal analysis on cord blood revealed only a normal 46,XX karyotype. Microsatellite analysis of 27 chromosome 20 loci confirmed maternal UPD for all 11 informative markers. Maternal heterodisomy was detected in two and maternal isodisomy in three loci. In the remaining six loci, a non-informative maternal UPD pattern was displayed, as mother and proband are homozygous for the same allele. To our knowledge this is the first reported case of maternal disomy 20 with normal karyotype ascertained by a mosaic trisomy 20 pregnancy. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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HADRIEN VANTHOMME JOSEPH KOLOWSKI LISA KORTE ALFONSO ALONSO 《Conservation biology》2013,27(2):281-291
We present the first community‐level study of the associations of both roads and other human disturbances with the distribution of mammals in Gabon (central Africa). Our study site was in an oil concession within a littoral mosaic landscape. We conducted surveys along 199 line transects and installed camera traps on 99 of these transects to document mammal presence and abundance. We used generalized linear mixed‐effect models to document associations between variables related to the ecosystem (land cover, topography, and hydrology), roads (coating, width of rights of way, condition, type of vehicle used on the road, traffic level, affiliation of users, and general type of road), and other human disturbances (urbanization, agriculture, hunting, logging, gathering, and industrial activities) and the abundance or presence of 17 species or groups of mammals including elephant (Loxodonta cyclotis), buffalo (Syncerus caffer), sitatunga (Tragelaphus spekei), red river hog (Potamochoerus porcus), smaller ungulates, gorilla (Gorilla gorilla), chimpanzee (Pan troglodytes), side‐striped jackal (Canis adustus), carnivores, monkeys, and large rodents. Some types of roads and other human disturbances were negatively associated with the abundance or presence of elephants, buffalos, gorillas, sitatungas, some monkeys, and duikers. The pattern of associations of mammals with roads and other human disturbances was diverse and included positive associations with road presence (red river hog, some monkeys, and duikers), agriculture (sitatunga, small carnivores, and large rodents) and industrial activities (sitatunga, red river hog, red duikers, and side‐striped jackal). Our results suggest that the community of mammals we studied was mostly affected by hunting, agriculture, and urbanization, which are facilitated by road presence. We recommend increased regulation of agriculture, hunting, and road building in the area. Distribución de una Comunidad de Mamíferos en Relación a Carreteras y Otras Perturbaciones Humanas en Gabón, Africa Central 相似文献
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Nodes,networks, and MUMs: Preserving diversity at all scales 总被引:14,自引:0,他引:14
The present focus of practical conservation efforts is limited in scope. This narrowness results in an inability to evaluate and manage phenomena that operate at large spatiotemporal scales. Whereas real ecological phenomena function in a space-time mosaic across a full hierarchy of biological entities and processes, current conservation strategies address a limited spectrum of this complexity. Conservation typically is static (time-limited), concentrates on the habitat content rather than the landscape context of protected areas, evaluates relatively homogeneous communities instead of heterogeneous landscapes, and directs attention to particular species populations and/or the aggregate statistic of species diversity. Insufficient attention has been given to broad ecological patterns and processes and to the conservation of species in natural relative abundance patterns (native diversity).The authors present a conceptual scheme that evaluates not only habitat content within protected areas, but also the landscape context in which each preserve exists. Nodes of concentrated ecological value exist in each landscape at all levels in the biological hierarchy. Integration of these high-quality nodes into a functional network is possible through the establishment of a system of interconnected multiple-use modules (MUMs). The MUM network protects and buffers important ecological entities and phenomena, while encouraging movement of individuals, species, nutrients, energy, and even habitat patches across space and time. An example is presented for the southeastern USA (south Georgia-north Florida), that uses riparian and coastal corridors to interconnect existing protected areas. This scheme will facilitate reintroduction and preservation of wide-ranging species such as the Florida panther, and help reconcile species-level and ecosystem-level conservation approaches. 相似文献
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Tropical arboreal ant mosaics: innate attraction and imprinting determine nest site selection in dominant ants 总被引:2,自引:0,他引:2
The modalities of nest site selection have, until now, been a key factor missing in the understanding of the arboreal ant
mosaic, the manipulation of which could be used to favour one ant species to the detriment of others in biological control.
We compared two dominant African arboreal ants of economic importance, Tetramorium aculeatum (Myrmicinae) and Oecophylla longinoda (Formicinae). The two species differed in terms of innate attraction to nesting site plants, their hierarchies of attractiveness
being nearly inverse. Winged females and workers were confronted with choice tests using four plant species. By using winged
females and workers originating from one of the plants to be tested, we showed the existence of a familiarisation process
which can supersede innate attraction in both species. We recorded the same effect in neonatal workers bred in the laboratory
in contact with a tested plant for 25 days after emergence, while mature workers could not be conditioned. There is, therefore,
early learning, with a sensitive period after which the influence of the environment ceases, suggesting that this is a true
imprinting process. Choice tests using neonates produced from larvae and pupae bred in the laboratory in contact with the
leaves of each tested plant permitted us to demonstrate the existence of pre-imaginal learning. Nest site selection therefore
depends on innate selective attraction and on environmental factors whose effect begins at the larval stage. There is, therefore,
the potential to “control” imprinting, allowing one ant species to be favoured to the detriment of others in monospecific
tree crop plantations.
Received: 25 May 1998 / Accepted after revision: 9 October 1998 相似文献
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污水稳定塘菌-藻生态系统去除与灭活植物病毒TMV研究 总被引:4,自引:0,他引:4
了解污水稳定塘生态系统去除与灭活植物病毒的效率与机理具有重要的理论和实际意义.对模型植物病毒———烟草花叶病毒(tobaccomosaicvirus,TMV)的实验结果显示:稳定塘系统中的悬浮固体(SS)可在短时间内吸附TMV且达到一个饱和值.纯培养的枯草芽孢杆菌及小球藻对TMV的存活无明显不良影响,而光合细菌和稳定塘中的混合细菌群却对TMV具有灭活作用.当它们同藻类形成菌藻共生体系时,对TMV的灭活速率分别从对照的每天0 0404log10(枯斑数·mL-1)升高到0 0783log10(枯斑数·mL-1)和0 075log10(枯斑数·mL-1) 因此,在污水稳定塘生态系统中,由于病毒对悬浮固体的吸附以及菌藻共生体系中微生物的作用可有效地去除与灭活植物病毒,其中悬浮固体吸附病毒并非真正意义上的灭活,稳定塘中存在的细菌特别是光合细菌对植物病毒的灭活才是最主要的因素. 相似文献
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Luke T. Kelly Andrew F. Bennett Michael F. Clarke Michael A. McCarthy 《Conservation biology》2015,29(2):473-481
Fire is used as a management tool for biodiversity conservation worldwide. A common objective is to avoid population extinctions due to inappropriate fire regimes. However, in many ecosystems, it is unclear what mix of fire histories will achieve this goal. We determined the optimal fire history of a given area for biological conservation with a method that links tools from 3 fields of research: species distribution modeling, composite indices of biodiversity, and decision science. We based our case study on extensive field surveys of birds, reptiles, and mammals in fire‐prone semi‐arid Australia. First, we developed statistical models of species’ responses to fire history. Second, we determined the optimal allocation of successional states in a given area, based on the geometric mean of species relative abundance. Finally, we showed how conservation targets based on this index can be incorporated into a decision‐making framework for fire management. Pyrodiversity per se did not necessarily promote vertebrate biodiversity. Maximizing pyrodiversity by having an even allocation of successional states did not maximize the geometric mean abundance of bird species. Older vegetation was disproportionately important for the conservation of birds, reptiles, and small mammals. Because our method defines fire management objectives based on the habitat requirements of multiple species in the community, it could be used widely to maximize biodiversity in fire‐prone ecosystems. Historiales de Incendios Óptimos para la Conservación de la Biodiversidad 相似文献