974 resultados para Lac-insects
Resumo:
Cover title.
Resumo:
Mode of access: Internet.
Resumo:
The collection was presented to the British museum (Nat. Hist.) by W. Wilson Saunders.
Resumo:
Mode of access: Internet.
Resumo:
"August 1997."
Resumo:
Cover title.
Resumo:
The Australian and zone harbours a surprising number of parthenogenetic organisms. including the well known case of the grasshopper Warramaba virgo. Less well known is the case of the stick insects of the Sipyloidea complex, which. despite its presence in the literature for over 15 years. has gone entirely unnoticed by workers in the field. We draw attention to the remarkable similarities between the evolution of parthenogenesis in Warramaba and Sipyloidea and analyse the geographic distributions of parthenogenetic and sexual forms with respect to six Climatic variables. We provide evidence that a combination of Climatic and vegetative barriers are responsible for the current distribution patterns in these taxa. Comparisons are also made with patterns of geographic parthenogenesis in lizards of the Heteronotia binoei complex. In general. there has been a strong tendency for parthenogenesis to originate via hybridization in the western part of the and zone with subsequent eastward spread throughout mulga woodlands and mallee shrublands where rainfall is both low and aseasonal. We propose that the hybridization events leading to parthenogenesis in these diverse taxa were driven by a common biogeographic process - that is, by range shifts associated with changes in aridity during the late Pleistocene.
Resumo:
Most multimeric lectins are adhesion molecules, promoting attachment and spreading on surface glycodeterminants. In addition, some lectins have counter-adhesion properties, detaching already spread cells which then acquire round or spindle-formed cell shapes. Since lectin-mediated adhesion and detachment is observed in haemocyte-like Drosophila cells, which have haemomucin as the major lectin-binding glycoprotein, the two opposite cell behaviours may be the result of lectin-mediated receptor rearrangements on the cell surface. To investigate oligomeric lectins as a possible extracellular driving force affecting cell shape changes, we examined lectin-mediated reactions in lepidopteran haemocytes after cytochalasin D-treatment and observed that while cell-spreading was dependent on F-actin, lectin-uptake was less dependent on F-actin. We propose a model of cell shape changes involving a dynamic balance between adhesion and uptake reactions. (C) 2004 Elsevier Ltd. All rights reserved.
Resumo:
Sibly et at. (Reports, 22 July 2005, p. 607) recently estimated the relationship between population size and growth rate for 1780 time series of various species. I explain why some aspects of their analysis are questionable and, therefore, why their results and estimation procedure should be used with care.
Resumo:
Clostridium difficile is a bacterial healthcare-associated infection, which houseflies Musca domestica may transfer due to their synanthropic nature. The aims of this thesis were to determine the ability of M. domestica to transfer C. difficile mechanically and to collect and identify flying insects in UK hospitals and classify any associated bacteria. M. domestica exposed to independent suspensions of vegetative cells and spores of C. difficile were able to mechanically transfer the bacteria on to agar for up to 4 hours following exposure. C. difficile could be recovered from fly excreta for 96hrs and was isolated from the M. domestica alimentary canal. Also confirmed was the carriage of C. difficile by M. domestica larvae, although it was not retained in the pupae or in the adults that subsequently developed. Flying insects were collected from ultra-violet light flytraps in hospitals. Flies (order Diptera) were the most commonly identified. Chironomidae were the most common flies, Calliphora vicina were the most common synanthropic fly and ‘drain flies’ were surprisingly numerous and represent an emerging problem in hospitals. External washings and macerates of flying insects were prepared and inoculated onto a variety of agars and following incubation bacterial colonies identified by biochemical tests. A variety of flying insects, including synanthropic flies (e.g. M. domestica and C. vicina) collected from UK hospitals harboured pathogenic bacteria of different species. Enterobacteriaceae were the group of bacteria most commonly isolated, followed by Bacillus spp, Staphylococci, Clostridia, Streptococci and Micrococcus spp. This study highlights the potential for M. domestica to contribute to environmental persistence and spread of C. difficile in hospitals. Also illustrated is the potential for flying insects to contribute to environmental persistence and spread of other pathogenic bacteria in hospitals and therefore the need to implement pest control as part of infection control strategies.
Resumo:
Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.