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101.
Laura K. Strawn Yrjo T. Gr?hn Steven Warchocki Randy W. Worobo Elizabeth A. Bihn Martin Wiedmann 《Applied and environmental microbiology》2013,79(24):7618-7627
Identification of management practices associated with preharvest pathogen contamination of produce fields is crucial to the development of effective Good Agricultural Practices (GAPs). A cross-sectional study was conducted to (i) determine management practices associated with a Salmonella- or Listeria monocytogenes-positive field and (ii) quantify the frequency of these pathogens in irrigation and nonirrigation water sources. Over 5 weeks, 21 produce farms in New York State were visited. Field-level management practices were recorded for 263 fields, and 600 environmental samples (soil, drag swab, and water) were collected and analyzed for Salmonella and L. monocytogenes. Management practices were evaluated for their association with the presence of a pathogen-positive field. Salmonella and L. monocytogenes were detected in 6.1% and 17.5% of fields (n = 263) and 11% and 30% of water samples (n = 74), respectively. The majority of pathogen-positive water samples were from nonirrigation surface water sources. Multivariate analysis showed that manure application within a year increased the odds of a Salmonella-positive field (odds ratio [OR], 16.7), while the presence of a buffer zone had a protective effect (OR, 0.1). Irrigation (within 3 days of sample collection) (OR, 6.0), reported wildlife observation (within 3 days of sample collection) (OR, 6.1), and soil cultivation (within 7 days of sample collection) (OR, 2.9) all increased the likelihood of an L. monocytogenes-positive field. Our findings provide new data that will assist growers with science-based evaluation of their current GAPs and implementation of preventive controls that reduce the risk of preharvest contamination. 相似文献
102.
Yee?Him Cheung Tenzin Gayden Philippe?M. Campeau Charles?A. LeDuc Donna Russo Van-Hung Nguyen Jiancheng Guo Ming Qi Yanfang Guan Steffen Albrecht Brenda Moroz Karen?W. Eldin James?T. Lu Jeremy Schwartzentruber David Malkin Albert?M. Berghuis Sherif Emil Richard?A. Gibbs David?L. Burk Megan Vanstone Brendan?H. Lee David Orchard Kym?M. Boycott Wendy?K. Chung Nada Jabado 《American journal of human genetics》2013,92(6):996-1000
Infantile myofibromatosis (IM) is the most common benign fibrous tumor of soft tissues affecting young children. By using whole-exome sequencing, RNA sequencing, and targeted sequencing, we investigated germline and tumor DNA in individuals from four distinct families with the familial form of IM and in five simplex IM cases with no previous family history of this disease. We identified a germline mutation c.1681C>T (p.Arg561Cys) in platelet-derived growth factor receptor β (PDGFRB) in all 11 affected individuals with familial IM, although none of the five individuals with nonfamilial IM had mutations in this gene. We further identified a second heterozygous mutation in PDGFRB in two myofibromas from one of the affected familial cases, indicative of a potential second hit in this gene in the tumor. PDGFR-β promotes growth of mesenchymal cells, including blood vessels and smooth muscles, which are affected in IM. Our findings indicate p.Arg561Cys substitution in PDGFR-β as a cause of the dominant form of this disease. They provide a rationale for further investigations of this specific mutation and gene to assess the benefits of targeted therapies against PDGFR-β in aggressive life-threatening familial forms of the disease. 相似文献
103.
Tomá? Albrecht Oddmund Kleven Jakub Kreisinger Terje Laskemoen Taiwo C. Omotoriogun Ulf Ottosson Ji?í Reif Ond?ej Sedlá?ek David Ho?ák Raleigh J. Robertson Jan T. Lifjeld 《Proceedings. Biological sciences / The Royal Society》2013,280(1752)
Sperm competition represents an important component of post-copulatory sexual selection. It has been argued that the level of sperm competition declines in birds towards the equator. However, to date, sperm competition estimates have been available mainly for avian species inhabiting the northern temperate zone. Here we apply a novel approach, using the coefficient of between-male variation (CVbm) in sperm size as an index for sperm competition risk, in a comparative analysis of 31 Afrotropical and 99 northern temperate zone passerine species. We found no difference in sperm competition risk between the two groups, nor any relationship with migration distance. However, a multivariate model indicated that sperm competition risk was highest in species with a combination of low body mass and few eggs per clutch. The effect of clutch size was most pronounced in tropical species, which indicates that sperm competition risk in tropical and temperate species is differently associated with particular life-history traits. Although tropical species had lower sperm competition risk than temperate zone species for overlapping clutch sizes, the idea of a generally reduced risk of sperm competition in tropical birds was not supported by our analysis. 相似文献
104.
105.
Calcareous grasslands are among the most species-rich plant communities in Europe with a particularly high nature conservation value. During the past centuries their distribution has markedly decreased, at least partly due to urbanization. Thus we investigated the effects of urbanization on species diversity along a spatio-temporal urbanization gradient from traditionally managed grassland to areas affected by urban developments, which was situated in the plains northwest of Munich, Germany. Both a RLQ analysis linking species and environmental traits, and a redundancy analysis of the plant community features showed that soil disturbance, soil sealing and mean temperature explained most of the environmental variation along the gradient. The species in urban habitats showed increased insect pollination, earlier flowering and prolonged seed longevity. While urbanization favored short-lived species with dysochorous dispersal, the reference grasslands harbored more wind-pollinated perennials with effective vegetative spread and relatively large, short-lived seeds. Compared to the urban sites, traditionally used grasslands had a higher species diversity, more threatened species and a lower proportion of non-natives. We conclude that even under conservation management, urban habitats are not capable of maintaining the original biodiversity. However, we also found threatened species occurring exclusively in urban sites. Hence, urbanization decreased the area and diversity of traditional calcareous grasslands, but it also established niches for endangered species which are not adapted to the living conditions in calcareous grasslands. 相似文献
106.
Ondřej Šťovíček Jakub Kreisinger Veronika Javůrková Tomáš Albrecht 《Journal of avian biology》2013,44(4):369-375
Conspecific brood parasitism (CBP) is a reproductive tactic whereby a parasitic female lays its eggs into the nests of other conspecific females. Genetic‐based data on the occurrence of CBP in birds, however, is still relatively scarce. We analysed prevalence of CBP in a ground‐nesting diving duck, the common pochard Aythya ferina, using a set of 17 microsatellites. Compared to related species, our population showed a relatively high level of CBP, with 39% of genotyped pochard eggs laid parasitically and 89% of nests containing ≥ 1 parasitic egg. In addition, we observed relatively high rates of interspecific brood parasitism (13% of eggs), caused predominantly by mallard Anas plathyrhynchos and tufted duck Aythya fuligula. CBP eggs had decreased hatching success compared to host eggs, with 65% of CBP and 95% of non‐CBP genotyped eggs hatching successfully. Our data suggest that this was probably due to improper timing of parasitic egglaying, which compromised synchronised hatching of CBP and host‐eggs. Despite high rates of CBP in our pochard popu lation, fitness costs associated with this reproductive tactic appear to be low for host females since neither clutch size nor host‐egg hatching probability were reduced due to CBP. 相似文献
107.
Gregory E. Demas Lance J. Kriegsfeld Kenneth D. Poss Susumu Tonegawa Randy J. Nelson 《Biological Rhythm Research》2013,44(3):282-289
Carbon monoxide (CO), generated in neurons by the enzyme heme oxygenase-2 (HO2), is postulated to be a gaseous signaling molecule in the mammalian brain. Because of the recent evidence suggesting an important role of another endogenously produced gas, nitric oxide (NO), in entrainment of circadian rhythms in mammals, we hypothesized that CO may also be involved in regulating these rhythms. Consistent with this idea, others have found a circadian rhythm of heme turnover and CO synthesis can be induced by bright light. Furthermore, HO2 is co-localized with guanylyl cyclase, the putative target of CO, throughout the brain, with high amounts of staining in the suprachiasmatic nucleus (SCN) of the hypothalamus. The goal of the present study was to evaluate the role of CO in photic entrainment in wild-type and HO2 deficient mice. HO2–/– mice did not display any abnormalities in circadian rhythmicity. Entrainment to a light–dark cycle, the ability to phase delay locomotor activity after a four hour phase shift in photoperiod, and the period of the free running rhythm (t) were similar between HO2–/– and wild-type mice. Taken together, these data suggest that CO does not play a major role in regulating circadian activity rhythms in mice. 相似文献
108.
Kaela B. Beauclerc Jeff Bowman Albrecht I. Schulte‐Hostedde 《Ecology and evolution》2013,3(7):2296-2309
Control of invasions is facilitated by their early detection, but this may be difficult when invasions are cryptic due to similarity between invaders and native species. Domesticated conspecifics offer an interesting example of cryptic invasions because they have the ability to hybridize with their native counterparts, and can thus facilitate the introgression of maladaptive genes. We assessed the cryptic invasion of escaped domestic American mink (Neovison vison) within their native range. Feral mink are a known alien invader in many parts of the world, but invasion of their native range is not well understood. We genetically profiled 233 captive domestic mink from different farms in Ontario, Canada and 299 free‐ranging mink from Ontario, and used assignments tests to ascertain genetic ancestries of free‐ranging animals. We found that 18% of free‐ranging mink were either escaped domestic animals or hybrids, and a tree regression showed that these domestic genotypes were most likely to occur south of a latitude of 43.13°N, within the distribution of mink farms in Ontario. Thus, domestic mink appear not to have established populations in Ontario in locations without fur farms. We suspect that maladaptation of domestic mink and outbreeding depression of hybrid and introgressed mink have limited their spread. Mink farm density and proximity to mink farms were not important predictors of domestic genotypes but rather, certain mink farms appeared to be important sources of escaped domestic animals. Our results show that not all mink farms are equal with respect to biosecurity, and thus that the spread of domestic genotypes can be mitigated by improved biosecurity. 相似文献
109.
Grace?S?Tan Rebecca?Lewandowski Michael?J?Mallory Randy?Strich Katrina?F?CooperEmail author 《Cell division》2013,8(1):9
Background
The execution of meiotic nuclear divisions in S. cerevisiae is regulated by protein degradation mediated by the anaphase promoting complex/cyclosome (APC/C) ubiquitin ligase. The correct timing of APC/C activity is essential for normal chromosome segregation. During meiosis, the APC/C is activated by the association of either Cdc20p or the meiosis-specific factor Ama1p. Both Ama1p and Cdc20p are targeted for degradation as cells exit meiosis II with Cdc20p being destroyed by APC/CAma1. In this study we investigated how Ama1p is down regulated at the completion of meiosis.Findings
Here we show that Ama1p is a substrate of APC/CCdc20 but not APC/CCdh1 in meiotic cells. Cdc20p binds Ama1p in vivo and APC/CCdc20 ubiquitylates Ama1p in vitro. Ama1p ubiquitylation requires one of two degradation motifs, a D-box and a “KEN-box” like motif called GxEN. Finally, Ama1p degradation does not require its association with the APC/C via its conserved APC/C binding motifs (C-box and IR) and occurs simultaneously with APC/CAma1-mediated Cdc20p degradation.Conclusions
Unlike the cyclical nature of mitotic cell division, meiosis is a linear pathway leading to the production of quiescent spores. This raises the question of how the APC/C is reset prior to spore germination. This and a previous study revealed that Cdc20p and Ama1p direct each others degradation via APC/C-dependent degradation. These findings suggest a model that the APC/C is inactivated by mutual degradation of the activators. In addition, these results support a model in which Ama1p and Cdc20p relocate to the substrate address within the APC/C cavity prior to degradation.110.
Bayu?Sisay?Tiruneh Byung-Hoon?Kim Daniel?R?Gallie Bijoyita?Roy Albrecht?G?von ArnimEmail author 《BMC biology》2013,11(1):123