Apparent segregation of null alleles ascribed to deletions of the ornithine transcarbamylase gene in congenital hyperammonaemia

Ornithine transcarbamylase (OTC) deficiency is an X-linked disorder of the urea cycle mapped to chromosome Xp21.1. Here, we show that apparent segregation of null alleles at the OTC locus and flanking polymorphic loci mimicked false maternity or false paternity in three affected families. Based on these observations, we suggest giving consideration to gene deletion when dealing with segregation of null alleles in OTC deficiency.     

Social synchronization of the activity rhythms of honeybees within a colony

Colonies and isolated bees of the Cape honeybee, Apis mellifera capensis Esch., were observed for evidence of circadian rhythmicity under constant conditions. It was found that colonies develop free-running activity rhythms in self-selected light-dark cycles, which are slightly shorter than 24 h. The periods of the activity rhythms of individual isolated bees were longer than 24 h in self-selected light-dark and constant light, while they were shorter than 24 h in constant darkness. A greater variability in period was found in the isolated bees than in the colonies. When the rhythms of colonies and individual bees from these colonies were measured simultaneously, the activities of the isolated bees drifted with respect to that of the colonies, their period being either longer or shorter than that of their own colony. After 12 days of isolation of individual bees from their colony, all coincidence between the phases of the two rhythms was lost. We conclude that the periods of common activity and common rest of the bees within a colony result from a mutual (social) synchronization of the rhythms of the individual bees.     

Benefits and limitations of whole genome versus targeted approaches for noninvasive prenatal testing for fetal aneuploidies

The goal to noninvasively detect fetal aneuploidies using circulating cell-free fetal DNA in the maternal plasma seems to be achieved by the use of massively parallel sequencing (MPS). To date, different MPS approaches exist, all aiming to deliver reliable results in a cost effective manner. The most widely used approach is the whole genome MPS method, in which sequencing is performed on maternal plasma to determine the presence of a fetal trisomy. To reduce costs targeted approaches, only analyzing loci from the chromosome(s) of interest has been developed. This review summarizes the different MPS approaches, their benefits and limitations and discusses the implications for future noninvasive prenatal testing. © 2013 John Wiley & Sons, Ltd.     

Insect herbivory and propagule pressure influence Cirsium vulgare invasiveness across the landscape

A current challenge in ecology is to better understand the magnitude, variation, and interaction in the factors that limit the invasiveness of exotic species. We conducted a factorial experiment involving herbivore manipulation (insecticide-in-water vs. water-only control) and seven densities of introduced nonnative Cirsium vulgare (bull thistle) seed. The experiment was repeated with two seed cohorts at eight grassland sites uninvaded by C. vulgare in the central Great Plains, USA. Herbivory by native insects significantly reduced thistle seedling density, causing the largest reductions in density at the highest propagule inputs. The magnitude of this herbivore effect varied widely among sites and between cohort years. The combination of herbivory and lower propagule pressure increased the rate at which new C. vulgare populations failed to establish during the initial stages of invasion. This experiment demonstrates that the interaction between biotic resistance by native insects, propagule pressure, and spatiotemporal variation in their effects were crucial to the initial invasion by this Eurasian plant in the western tallgrass prairie.     

瑞士库珀公司与供货商们的紧密合作

库珀(COOP)公司是瑞士最大的通过有利于环境保护以及公平贸易的销售商.其可持续的零售工作主要集中在4种具有"生态旗舰"标签的产品:有机和放养的食品、有机纺织品和化妆品,互利交易商品以及其它产品.这些产品的成功销售主要依靠与供货商的紧密合作.作为商品的质量担保人库珀公司通过采用指导原则、行为原则、合格证标准和独立控制原则以确保其经营商品达到标准.以它的有机棉纺织品为例,库珀公司帮助那些发展中国家的农民进行了从传统的种植方法到有机品种种植的过渡.     

Batch-test study on the dechlorination of 1,1,1-trichloroethane in contaminated aquifer material by zero-valent iron

Chlorinated aliphatic hydrocarbons are common groundwater contaminants. One possible remediation option is in-situ reductive dechlorination by zero-valent iron, either by direct injection or as reactive barriers. Chlorinated ethenes (tetrachloroethene: PCE; trichloroethene: TCE) have received extensive attention in this context. However, another common groundwater pollutant, 1,1,1-trichlorethane (TCA), has attracted much less attention. We studied TCA reduction by three types of granular zero-valent irons in a series of batch experiments using polluted groundwater, with and without added aquifer material. Two types of iron were able to reduce TCA completely with no daughter product concentration increases (1,1-dichloroethane: DCA; chloroethane: CA). One type of iron showed slower reduction, with intermediate rise of DCA and CA concentrations. When evaluating the formation of daughter products, the tests on the groundwater alone showed different results than the groundwater plus aquifer batches: DCA did not temporarily accumulate in the batches with added aquifer material, contrary to the batches without added aquifer material. 1,1-dichloroethene (DCE, also present in the groundwater as an abiotic degradation product of TCA) was also reduced slower in the batches without added aquifer material than in the batches with aquifer material. Redox potentials gradually decreased to low values in batches with aquifer material without iron, while the batches with groundwater alone maintained a constant higher redox potential. Either adsorption processes or microbiological activity in the samples could explain these phenomena. Polymerase Chain Reaction (PCR: a targeted gene probe technique) for chlorinated aliphatic compound (CAH)-degrading bacteria confirmed the presence of Dehalococcoides sp. (chloroethene-degraders) but was negative for Desulfobacterium autotrophicum (a known co-metabolic TCA degrader). DCA reduction was rate determining: first-order half-lives of 300-350 h were observed. TCA was fully removed within hours. CA is resistant to reduction by zero-valent iron but it is known to hydrolyze easily. Since CA did not accumulate in our batches, it may have disappeared by the latter mechanism or it may not have formed as a major daughter product.