Alexander Böhm (1971–2012)

On November 28, 2012 Alexander (Alex) Böhm, a bacterial geneticist, died at age 41, only a few months after taking up a position as an assistant professor at the LOEWE Center for Synthetic Microbiology in Marburg, Germany. Earlier in 2012 Alex had been diagnosed with an aggressive form of thyroid cancer that left him little time to live his scientific and personal dreams.     

Pediatric Invasive Pneumococcal Disease Caused by Vaccine Serotypes following the Introduction of Conjugate Vaccination in Denmark

A seven-valent pneumococcal conjugate vaccine (PCV7) was introduced in the Danish childhood immunization program (2+1 schedule) in October 2007, followed by PCV13 starting from April 2010. The nationwide incidence of IPD among children younger than 5 years nearly halved after the introduction of PCV7 in the program, mainly due to a decline in IPD caused by PCV7-serotypes. We report the results from a nationwide population-based cohort study of laboratory confirmed IPD cases in children younger than 5 years during October 1, 2007 to December 31, 2010 and describe the characteristics of children suspected to present with a vaccine failure. The period between April 19 and December 31, 2010 was considered a PCV7/PCV13 transitional period, where both vaccines were offered. We identified 45 episodes of IPD caused by a PCV7 serotype (23% of the total number) and 105 (55%) caused by one of the 6 additional serotypes in PCV13. Ten children had received at least one PCV7 dose before the onset of IPD caused by a PCV7 serotype. Seven children were considered to be incompletely vaccinated before IPD, but only three cases fulfilled the criteria of vaccine failure (caused by serotypes 14, 19F and 23F). One case of vaccine failure was observed in a severely immunosuppressed child following three PCV7 doses, and two cases were observed in immunocompetent children following two infant doses before they were eligible for their booster. None of the IPD cases caused by the additional PCV13 serotypes had been vaccinated by PCV13 and there were therefore no PCV13-vaccine failures in the first 8-months after PCV13 introduction in Denmark.     

Characteristics of rapid eye movement sleep behavior disorder in narcolepsy

The basal forebrain (BF) plays an important role in regulating cortical activity and sleep/wake states. Both cholinergic and non-cholinergic neurons of the BF project to the cerebral cortex and hippocampus, whereas the hypothalamus and brainstem nuclei are mostly innervated by non-cholinergic BF neurons. Neurons in the BF show various discharge profiles in relation to cortical activity and behavioral states and are differentially modulated by neurotransmitters of other sleep/wake regulatory neurons. Recent technical advances have made it possible to correlate discharge profiles of single BF neurons during sleep/wake states with their neurochemical phenotypes, and to make selective lesions of certain cell types. The goal of this review is to summarize the current knowledge of the anatomy and sleep/wake regulatory functions of cholinergic and non-cholinergic BF neurons. We will first review the anatomical heterogeneity of BF neurons, and then discuss recent evidence for the firing patterns of BF cholinergic and non-cholinergic neurons during natural sleep–wake patterns, and finally, discuss their roles in sleep homeostasis. It is proposed that through different neurotransmitters, projections, and state-regulated activity, the cholinergic and non-cholinergic BF neurons collectively and differently regulate cortical activity and sleep-wake states.

     

Glutamine Metabolism Regulates Proliferation and Lineage Allocation in Skeletal Stem Cells

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Incorporating experimental design and error into coalescent/mutation models of population history

Coalescent theory provides a powerful framework for estimating the evolutionary, demographic, and genetic parameters of a population from a small sample of individuals. Current coalescent models have largely focused on population genetic factors (e.g., mutation, population growth, and migration) rather than on the effects of experimental design and error. This study develops a new coalescent/mutation model that accounts for unobserved polymorphisms due to missing data, sequence errors, and multiple reads for diploid individuals. The importance of accommodating these effects of experimental design and error is illustrated with evolutionary simulations and a real data set from a population of the California sea hare. In particular, a failure to account for sequence errors can lead to overestimated mutation rates, inflated coalescent times, and inappropriate conclusions about the population. This current model can now serve as a starting point for the development of newer models with additional experimental and population genetic factors. It is currently implemented as a maximum-likelihood method, but this model may also serve as the basis for the development of Bayesian approaches that incorporate experimental design and error.     

Adipose tissue interleukin-18 mRNA and plasma interleukin-18: effect of obesity and exercise

Objectives: Obesity and a physically inactive lifestyle are associated with increased risk of developing insulin resistance. The hypothesis that obesity is associated with increased adipose tissue (AT) interleukin (IL)‐18 mRNA expression and that AT IL‐18 mRNA expression is related to insulin resistance was tested. Furthermore, we speculated that acute exercise and exercise training would regulate AT IL‐18 mRNA expression. Research Methods and Procedures: Non‐obese subjects with BMI < 30 kg/m² (women: n = 18; men; n = 11) and obese subjects with BMI >30 kg/m² (women: n = 6; men: n = 7) participated in the study. Blood samples and abdominal subcutaneous AT biopsies were obtained at rest, immediately after an acute exercise bout, and at 2 hours or 10 hours of recovery. After 8 weeks of exercise training of the obese group, sampling was repeated 48 hours after the last training session. Results: AT IL‐18 mRNA content and plasma IL‐18 concentration were higher (p < 0.05) in the obese group than in the non‐obese group. AT IL‐18 mRNA content and plasma IL‐18 concentration was positively correlated (p < 0.05) with insulin resistance. While acute exercise did not affect IL‐18 mRNA expression at the studied time‐points, exercise training reduced AT IL‐18 mRNA content by 20% in both sexes. Discussion: Because obesity and insulin resistance were associated with elevated AT IL‐18 mRNA and plasma IL‐18 levels, the training‐induced lowering of AT IL‐18 mRNA content may contribute to the beneficial effects of regular physical activity with improved insulin sensitivity.     

Introduction of Mysis relicta (Mysida) reduces niche segregation between deep-water Arctic charr morphs

Hydrobiologia - Understanding the concordance between aquatic assemblages in ecological assessments and their responses to human-induced disturbances are fundamental steps toward achieving...     

Exploring trophic niches and parasite communities of sympatric Arctic charr and brown trout populations of southern Norway

Hydrobiologia - Catchment-scale variation between lake habitats has the potential to simultaneously influence the trophic niche and parasite community of fish hosts. In this study, we investigated...     

Development of efficient suicide mechanisms for biological containment of bacteria.

To optimize plasmid containment, we have systematically investigated the factors that limit the killing efficiency of a suicide system based on the relF gene from Escherichia coli controlled by inducible lac promoters and placed on plasmids. In induction experiments with this suicide system, killing efficiency was unaffected by temperature and growth medium; there was no requirement for great promoter strength or high plasmid copy number. We could demonstrate that the factors limiting killing were the mutation rate of the suicide function and the reduced growth rate caused by a basal level of expression of the suicide gene during normal growth, which can give a selective growth advantage to cells with mutated suicide functions. The capacity of the plasmid-carried killing system to contain the plasmid was tested in transformation, transduction, and conjugational mobilization. The rate of plasmid transfer detected in these experiments seemed too high to provide adequate biological containment. As expected from the induction experiments, plasmids that escaped containment in these transfer experiments turned out to be mutated in the suicide function. With lac-induced suicide as a test, the efficiency of the system was improved by tightening the repression of the suicide gene, thereby preventing selection of cells mutated in the killing function. Reduction of the mutational inactivation rate of the suicide system by duplication of the suicide function augmented the efficiency of the suicide dramatically. These results permit the construction of extremely efficient biological containment systems.