Neuronal synchrony during anesthesia: a thalamocortical model

There is growing evidence in favor of the temporal-coding hypothesis that temporal correlation of neuronal discharges may serve to bind distributed neuronal activity into unique representations and, in particular, that θ (3.5-7.5 Hz) and δ (0.5 < 3.5 Hz) oscillations facilitate information coding. The θ- and δ-rhythms are shown to be involved in various sleep stages, and during anesthesia, they undergo changes with the depth of anesthesia. We introduce a thalamocortical model of interacting neuronal ensembles to describe phase relationships between θ- and δ-oscillations, especially during deep and light anesthesia. Asymmetric and long-range interactions among the thalamocortical neuronal oscillators are taken into account. The model results are compared with experimental observations. The δ- and θ-activities are found to be separately generated and are governed by the thalamus and cortex, respectively. Changes in the degree of intraensemble and interensemble synchrony imply that the neuronal ensembles inhibit information coding during deep anesthesia and facilitate it during light anesthesia.     

Developmental plasticity of the locomotor activity rhythm of Drosophila melanogaster

We used four replicate outbred populations of Drosophila melanogaster to investigate whether the light regimes experienced during the pre-adult (larval and pupal) and early adult stages influence the free-running period (τ_DD) of the circadian locomotor activity rhythm of adult flies. In a series of two experiments four different populations of flies were raised from egg to eclosion in constant light (LL), in light/dark (LD) 12:12 h cycle, and in constant darkness (DD). In the first experiment the adult male and female flies were directly transferred into DD and their locomotor activity was monitored, while in the second experiment the locomotor activity of the emerging adult flies was first assayed in LD 12:12 h for 15 days and then in DD for another 15 days. The τ_DD of the locomotor activity rhythm of flies that were raised in all the three light regimes, LL, LD 12:12 h and in DD was significantly different from each other. The τ_DD of the locomotor activity rhythm of the flies, which were raised in DD during their pre-adult stages, was significantly shorter than that of flies that were raised as pre-adults in LL regime, which in turn was significantly shorter than that of flies raised in LD 12:12 h regime. This pattern was consistent across both the experiments. The results of our experiments serve to emphasise the fact that in order to draw meaningful inferences about circadian rhythm parameters in insects, adequate attention should be paid to control and specify the environment in which pre-adult rearing takes place. The pattern of pre-adult and early adult light regime effects that we see differs from that previously observed in studies of mutant strains of D. melanogaster, and therefore, also points to the potential importance of inter-strain differences in the response of circadian organisation to external influences.     

Effect of pH,temperature and alcohols on the stability of glycosylated and deglycosylated stem bromelain

The biological significance of the carbohydrate moiety of a glycoprotein has been a matter of much speculation. In the present work, we have chosen stem bromelain fromAnanas comosus as a model to investigate the role of glycosylation of proteins. Stem bromelain is a thiol protease which contains a single hetero-oligosaccharide unit per molecule. Here, the deglycosylated form of the enzyme was obtained by periodate oxidation. The differences in the glycosylated and deglycosylated forms of the glycoprotein have been studied at various temperatures and pH values, using probes such as loss of enzyme activity and by the changes in fluorescence and circular dichroism spectra. Deglycosylated bromelain showed decreased enzyme activity and perturbed fluorescence and circular dichroism spectra. In addition to this, a comparative study of their activities in different organic solvents showed a marked decrease in case of deglycosylated form of the enzyme. It is thus concluded that glycosylation contributes towards the functional stability of glycoenzymes.     

Deletion mutants of protective antigen that inhibit anthrax toxin both in vitro and in vivo

The anthrax toxin complex is primarily responsible for most of the symptoms of anthrax. This complex is composed of three proteins, anthrax protective antigen, anthrax edema factor, and anthrax lethal factor. The three proteins act in binary combination of protective antigen plus edema factor (edema toxin) and protective antigen plus lethal factor (lethal toxin) that paralyze the host defenses and eventually kill the host. Both edema factor and lethal factor are intracellularly acting proteins that require protective antigen for their delivery into the host cell. In this study, we show that deletion of certain residues of protective antigen results in variants of protective antigen that inhibit the action of anthrax toxin both in vitro and in vivo. These mutants protected mice against both lethal toxin and edema toxin challenge, even when injected at a 1:8 ratio relative to the wild-type protein. Thus, these mutant proteins are promising candidates that may be used to neutralize the action of anthrax toxin.     

The effect of different light regimes on adult life span in Drosophila melanogaster is partly mediated through reproductive output

The effects of different light regimes on the fitness of organisms have typically been studied using mean or median adult life span as the sole index of physiological well-being. It is, however, known that life span is inversely related to reproductive output in many species. Moreover, the effects of a given environmental treatment on life span can be due to effects on either age-independent mortality or the "rate of aging," or a combination of both. Drawing evolutionary inferences from the effects of light regime on mean or median adult life span alone is difficult and, at best, speculative. We examined the effects of constant light (LL), alternating light-dark cycles (LD 12:12 h), and constant darkness (DD) on the life span of reproducing and virgin flies in four populations of Drosophila melanogaster and also estimated lifetime fecundity in the three light regimes. The light regime effects on life span were further dissected by examining the age-independent mortality and the Gompertz rate of aging under the three light regimes. While mean adult life span of reproducing males and females and virgin females was significantly shorter in LL compared to LD 12:12 h and DD, life-time egg production was highest in LL. Life span of virgin males was not significantly affected by light regime. The rate of aging in reproducing females was higher in LL as compared to DD, whereas age-independent mortality was higher in DD. As reproductive output, especially early in life, is a far more significant contributor to fitness than is life span, our results suggest that the earlier reported deleterious effects of LL on fitness are partly an artifact of examining life span alone, without considering other components of adult fitness that trade off with life span. Our results suggest that detailed investigation of the effects of light regime on the physiological and behavioral processes that accompany reproduction is necessary to fully understand the effects of different light regimes on adult fitness in Drosophila.     

Giving the silent majority a stronger voice? Initiatives to empower Muslim women as part of the UK's ‘War on Terror’

Abstract

This article provides a gendered analysis of the ‘War on Terror’ in the UK context. Specifically it looks at initiatives to empower Muslim women, which were part of New Labour's Preventing Violent Extremism (PVE) agenda, the impetus for which stemmed from the idea that, as ‘the silent majority’, women need to be given a ‘stronger voice’. Based on analysis of qualitative interviews, this article situates these initiatives within a broader policy landscape of debates on multiculturalism, community cohesion and Britishness. It explores interviewees' understandings of Muslim women's silence in relation to those suggested by policy discourse, considering the ways in which the state's attempt to ‘give voice’ worked in practice. I argue that the operation of such initiatives continued to constrain Muslim women's voices, restricting ‘voice’ to a narrow range of speakers speaking about a narrow range of issues.     

Effect of Different Light Regimes on Pre-Adult Fitness in Drosophila melanogaster Populations Reared in Constant Light for over Six Hundred Generations

Egg to eclosion development time and survivorship were assayed on four laboratory populations of Drosophila melanogaster that had been reared for over 600 generations in continuous light (LL) and constant temperature. The assays were performed in three environments: continuous light (LL), periodically varying light/dark cycles (LD 12:12 hr), and continuous darkness (DD). Development time in LL was significantly less than that in LD, which, in turn, was significantly less than that in DD, whereas survivorship did not differ significantly among the three treatments. The results indicate that individuals from Drosophila populations routinely maintained in LL do not suffer any deleterious effects of LL treatment on pre-adult fitness. Other studies on these populations have shown that free-running period (t) of the eclosion rhythm in DD is greater than that in LD. Our results are, thus, also consistent with the notion that development time may be a function of the free-running period.