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51.
An analysis of restriction fragment length polymorphism (RFLP) using eight
residential insertion sequence (IS) elements as hybridization probes
reveals that the genome of resting bacteria is more dynamic than it was
long believed. Escherichia coli strains stored in agar stabs for up to 30
yr accumulate a genetic variation which is correlated to time of storage.
This spontaneous mutagenesis is often IS-specific, with particularly high
activity for IS5, and thus suggests that transpositional DNA rearrangements
are a major cause for the observed genetic polymorphism. The RFLP patterns
indicate a burst of IS30 transposition to occur occasionally. Mutation rate
is estimated by two different methods to roughly 10(-5) IS-related DNA
rearrangements per bacterial chromosome per hour of storage for the eight
IS elements studied. A pedigree derived from the RFLP data reveals that
populations had evolved independently in each stab and showed no signs of
convergence. Relics of an assumed ancestral population were still present
in the stab cultures, but the elder stabs provided mostly mutants. These
results indicate that cells placed under nutritional deprivation might have
a highly plastic genome and suggest that such plasticity might play an
adaptive role.
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R.?M.?Dew S.?M.?RehanEmail author S.?M.?Tierney L.?B.?Chenoweth M.?P.?Schwarz 《Insectes Sociaux》2012,59(2):207-214
Evolutionary origins of highly eusocial organization involving morphological castes have been very rare, yet these origins
have often led to enormous diversification and ecological success. This suggests that once an apparently severe selective
barrier to highly eusocial behaviour is overcome, major new adaptive landscapes open up. One would therefore expect a discontinuity
in patterns of evolutionary change across this barrier. However, we do not know if highly eusocial organization has evolved
incrementally from less complex societies, or if it has involved some kind of evolutionary leap. Our study examines this issue
using colony size data from 33 allodapine bee species, with a crown age of ca. 47 Mya. Our species cover all major allodapine
clades, and include Exoneurella tridentata, the only known allodapine with morphologically discrete castes. Phylogenetic analyses indicate a strong effect of phylogeny
on the evolution of maximum brood size, but the effect of phylogeny on maximum colony size (number of adults) depends on whether
E. tridentata is excluded or included in analyses. We found no evidence of punctuational change in maximum colony or brood sizes over the
phylogeny as a whole, but colony and brood sizes in E. tridentata fall well beyond variation among the other allodapines. Colony size in E. tridentata therefore represents an evolutionary outcome that does not fit within the kinds of incremental changes found in other allodapines.
We propose that E. tridentata indicates the crossing of an important threshold, and this has entailed some very unusual ecological circumstances. 相似文献
55.
Jessica McClelland Maria Kekic Natali Bozhilova Steffen Nestler Tracy Dew Frederique Van den Eynde Anthony S. David Katya Rubia Iain C. Campbell Ulrike Schmidt 《PloS one》2016,11(3)
Background
Anorexia nervosa (AN) is associated with morbid fear of fatness, extreme food restriction and altered self-regulation. Neuroimaging data implicate fronto-striatal circuitry, including the dorsolateral prefrontal cortex (DLPFC).Methods
In this double-blind parallel group study, we investigated the effects of one session of sham-controlled high-frequency repetitive transcranial magnetic stimulation (rTMS) to the left DLPFC (l-DLPFC) in 60 individuals with AN. A food exposure task was administered before and after the procedure to elicit AN-related symptoms.Outcomes
The primary outcome measure was ‘core AN symptoms’, a variable which combined several subjective AN-related experiences. The effects of rTMS on other measures of psychopathology (e.g. mood), temporal discounting (TD; intertemporal choice behaviour) and on salivary cortisol concentrations were also investigated. Safety, tolerability and acceptability were assessed.Results
Fourty-nine participants completed the study. Whilst there were no interaction effects of rTMS on core AN symptoms, there was a trend for group differences (p = 0.056): after controlling for pre-rTMS scores, individuals who received real rTMS had reduced symptoms post-rTMS and at 24-hour follow-up, relative to those who received sham stimulation. Other psychopathology was not altered differentially following real/sham rTMS. In relation to TD, there was an interaction trend (p = 0.060): real versus sham rTMS resulted in reduced rates of TD (more reflective choice behaviour). Salivary cortisol concentrations were unchanged by stimulation. rTMS was safe, well–tolerated and was considered an acceptable intervention.Conclusions
This study provides modest evidence that rTMS to the l-DLPFC transiently reduces core symptoms of AN and encourages prudent decision making. Importantly, individuals with AN considered rTMS to be a viable treatment option. These findings require replication in multiple-session studies to evaluate therapeutic efficacy.Trial Registration
www.Controlled-Trials.com ISRCTN22851337 相似文献56.
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Matagne Heutink Marcel WM Post Peter Luthart Lilian EMA Pfennings Catja A Dijkstra Eline Lindeman 《BMC neurology》2010,10(1):96
Background
Most people with a spinal cord injury rate neuropathic pain as one of the most difficult problems to manage and there are no medical treatments that provide satisfactory pain relief in most people. Furthermore, psychosocial factors have been considered in the maintenance and aggravation of neuropathic spinal cord injury pain. Psychological interventions to support people with spinal cord injury to deal with neuropathic pain, however, are sparse. The primary aim of the CONECSI (COping with NEuropathiC Spinal cord Injury pain) trial is to evaluate the effects of a multidisciplinary cognitive behavioural treatment programme on pain intensity and pain-related disability, and secondary on mood, participation in activities, and life satisfaction. 相似文献60.
Pehun Pereyra Gerber Lidia M. Duncan Edward JD Greenwood Sara Marelli Adi Naamati Ana Teixeira-Silva Thomas WM Crozier Ildar Gabaev Jun R. Zhan Thomas E. Mulroney Emily C. Horner Rainer Doffinger Anne E. Willis James ED Thaventhiran Anna V. Protasio Nicholas J. Matheson 《PLoS pathogens》2022,18(2)
Efforts to define serological correlates of protection against COVID-19 have been hampered by the lack of a simple, scalable, standardised assay for SARS-CoV-2 infection and antibody neutralisation. Plaque assays remain the gold standard, but are impractical for high-throughput screening. In this study, we show that expression of viral proteases may be used to quantitate infected cells. Our assays exploit the cleavage of specific oligopeptide linkers, leading to the activation of cell-based optical biosensors. First, we characterise these biosensors using recombinant SARS-CoV-2 proteases. Next, we confirm their ability to detect viral protease expression during replication of authentic virus. Finally, we generate reporter cells stably expressing an optimised luciferase-based biosensor, enabling viral infection to be measured within 24 h in a 96- or 384-well plate format, including variants of concern. We have therefore developed a luminescent SARS-CoV-2 reporter cell line, and demonstrated its utility for the relative quantitation of infectious virus and titration of neutralising antibodies. 相似文献