Use of the Meganuclease I-SceI of Saccharomyces cerevisiae to select for gene deletions in actinomycetes

The search for new natural products is leading to the isolation of novel actinomycete species, many of which will ultimately require genetic analysis. Some of these isolates will likely exhibit low intrinsic frequencies of homologous recombination and fail to sporulate under laboratory conditions, exacerbating the construction of targeted gene deletions and replacements in genetically uncharacterised strains. To facilitate the genetic manipulation of such species, we have developed an efficient method to generate gene or gene cluster deletions in actinomycetes by homologous recombination that does not introduce any other changes to the targeted organism's genome. We have synthesised a codon optimised I-SceI gene for expression in actinomycetes that results in the production of the yeast I-SceI homing endonuclease which produces double strand breaks at a unique introduced 18 base pair recognition sequence. Only those genomes that undergo homologous recombination survive, providing a powerful selection for recombinants, approximately half of which possess the desired mutant genotype. To demonstrate the efficacy and efficiency of the system, we deleted part of the gene cluster for the red-pigmented undecylprodiginine complex of compounds in Streptomyces coelicolor M1141. We believe that the system we have developed will be broadly applicable across a wide range of actinomycetes

Use of CNS medications and cognitive decline in the aged: a longitudinal population-based study

<p>Abstract</p> <p>Background</p> <p>Previous studies have found associations between the use of central nervous system medication and the risk of cognitive decline in the aged. Our aim was to assess whether the use of a single central nervous system (CNS) medication and, on the other hand, the combined use of multiple CNS medications over time are related to the risk of cognitive decline in an older (≥ 65 yrs) population that is cognitively intact at baseline.</p> <p>Methods</p> <p>We conducted a longitudinal population-based study of cognitively intact older adults. The participants were 65 years old or older and had Mini-Mental State Examination (MMSE) sum scores of 24 points or higher. The study included a 7.6-year follow-up. The use of benzodiazepines and related drugs (BZDs), antipsychotics (APs), antidepressants (ADs), opioids (Ops), anticholinergics (AChs) and antiepileptics (AEs) was determined at baseline and after a 7.6-years of the follow-up period. Cognitive functioning was used as an outcome variable measured with MMSE at baseline and at the mean follow-up of 7.6 years. Control variables were adjusted with analyses of covariance.</p> <p>Results</p> <p>After adjusting for control variables, the use of Ops and the concomitant use of Ops and BZDs as well as the use of Ops and any CNS medication were associated with cognitive decline. The use of AChs was associated with decline in cognitive functioning only in men.</p> <p>Conclusions</p> <p>Of all the CNS medications analyzed in this study, the use of Ops may have the greatest effect on cognitive functioning in the ageing population. Due to small sample sizes these findings cannot be generalized to the unselected ageing population. More studies are needed concerning the long-term use of CNS medications, especially their concomitant use, and their potential cognitive effects.</p

Ten-year trends in benzodiazepine use in the Dutch population

Background In the past decades knowledge on adequate treatment of affective disorders and awareness of the negative consequences of long-term benzodiazepine use increased. Therefore, a decrease in benzodiazepine use is expected, particularly in prolonged use. The aim of this study was to assess time trends in benzodiazepine use. Methods and material Data from the Longitudinal Aging Study Amsterdam (LASA) were used to investigate trends in benzodiazepine use between 1992 and 2002 in two population-based samples aged 55-64 years. Differences between the two samples with respect to benzodiazepine use and to sociodemographic, physical health and mental health characteristics were described and tested with chi- square tests and logistic regression analyses. Results Benzodiazepine use remained stable over 10 years, with 7.8% in LASA-1 (n = 874) and 7.9% in LASA-2 (n = 919) (p = 0.90) with a persisting preponderance in women and in people with low education, low income, chronic physical diseases, functional limitations, cognitive impairment, depression, anxiety complaints, sleep problems and when using antidepressants. Long-term use remained high with 70% in 1992 and 80% in 2002 of total benzodiazepine use. Conclusion In the Dutch population aged 55-64, overall benzodiazepine use remained stable from 1992 to 2002, with a high proportion of long-term users, despite the effort to reduce benzodiazepine use and the renewal of the guidelines. More effort should be made to decrease prolonged benzodiazepine use in this middle-aged group, because of the increasing risks with ageing. © The Author(s) 2011

Evidence for the stability of the West Antarctic Ice Sheet divide for 1.4 million years

Past fluctuations of the West Antarctic Ice Sheet (WAIS) are of fundamental interest because of the possibility of WAIS collapse in the future and a consequent rise in global sea level. However, the configuration and stability of the ice sheet during past interglacial periods remains uncertain. Here we present geomorphological evidence and multiple cosmogenic nuclide data from the southern Ellsworth Mountains to suggest that the divide of the WAIS has fluctuated only modestly in location and thickness for at least the last 1.4 million years. Fluctuations during glacial–interglacial cycles appear superimposed on a long-term trajectory of ice-surface lowering relative to the mountains. This implies that as a minimum, a regional ice sheet centred on the Ellsworth-Whitmore uplands may have survived Pleistocene warm periods. If so, it constrains the WAIS contribution to global sea level rise during interglacials to about 3.3 m above present

Proof theory for indexed nested sequents

International audienceFitting's indexed nested sequents can be used to give deduc-tive systems to modal logics which cannot be captured by pure nested sequents. In this paper we show how the standard cut-elimination procedure for nested sequents can be extended to indexed nested sequents, and we discuss how indexed nested sequents can be used for intuitionistic modal logics