Decreased tuftsin concentrations in patients who have undergone splenectomy.

Serum tuftsin concentrations were measured, using a radioimmunoassay developed in Israel, in normal subjects and in patients who had undergone splenectomy. Concentrations in those who had undergone traumatic and elective splenectomy were much lower. The tuftsin concentration in 38 patients with Hodgkin''s disease who had undergone splenectomy during staging laparotomy was not significantly different from the mean concentration in other patients who had had elective splenectomy. In four patients who underwent splenectomy for non-malignant haematological disorders measurements made before and after operation showed that tuftsin concentrations fell significantly in the days after operation. The increased susceptibility to overwhelming infections of patients with Hodgkin''s disease and others who have undergone splenectomy may be related to the low tuftsin concentrations. As pre-splenectomy tuftsin concentrations in patients with Hodgkin''s disease were normal, the practice of performing staging laparotomy and splenectomy in patients with Hodgkin''s disease should perhaps be reconsidered.     

Genetic changes in mating activity in laboratory strains of Drosophila subobscura

Eleven populations of Drosophila subobscura that had been maintained in laboratory conditions during different periods of time were examined for evidence of genetic divergence in mating activity. The results indicate that mating activity increases with the time of maintenance under laboratory conditions.     

A unified framework for diversity gradients: the adaptive trait continuum

Aim Adaptive trait continua are axes of covariation observed in multivariate trait data for a given taxonomic group. These continua quantify and summarize life‐history variation at the inter‐specific level in multi‐specific assemblages. Here we examine whether trait continua can provide a useful framework to link life‐history variation with demographic and evolutionary processes in species richness gradients. Taking an altitudinal species richness gradient for Mediterranean butterflies as a study case, we examined a suite of traits (larval diet breadth, adult phenology, dispersal capacity and wing length) and species‐specific habitat measures (temperature and aridity breadth). We tested whether traits and species‐specific habitat measures tend to co‐vary, whether they are phylogenetically conserved, and whether they are able to explain species distributions and spatial genetic variation in a large number of butterfly assemblages. Location Catalonia, Spain. Methods We formulated predictions associated with species richness gradients and adaptive trait continua. We applied principal components analyses (PCAs), structural equation modelling and phylogenetic generalized least squares models. Results We found that traits and species‐specific habitat measures covaried along a main PCA axis, ranging from multivoltine trophic generalists with high dispersal capacity to univoltine (i.e. one generation per year), trophic specialist species with low dispersal capacity. This trait continuum was closely associated with the observed distributions along the altitudinal gradient and predicted inter‐specific differences in patterns of spatial genetic variability (F_ST and genetic distances), population responses to the impacts of global change and local turnover dynamics. Main conclusions The adaptive trait continuum of Mediterranean butterflies provides an integrative and mechanistic framework to: (1) analyse geographical gradients in species richness, (2) explain inter‐specific differences in population abundances, spatial distributions and demographic trends, (3) explain inter‐specific differences in patterns of genetic variation (F_ST and genetic distances), and (4) study specialist–generalist life‐history transitions frequently involved in butterfly diversification processes.     

Multi‐generational long‐distance migration of insects: studying the painted lady butterfly in the Western Palaearctic

Long‐range, seasonal migration is a widespread phenomenon among insects, allowing them to track and exploit abundant but ephemeral resources over vast geographical areas. However, the basic patterns of how species shift across multiple locations and seasons are unknown in most cases, even though migrant species comprise an important component of the temperate‐zone biota. The painted lady butterfly Vanessa cardui is such an example; a cosmopolitan continuously‐brooded species which migrates each year between Africa and Europe, sometimes in enormous numbers. The migration of 2009 was one of the most impressive recorded, and thousands of observations were collected through citizen science programmes and systematic entomological surveys, such as high altitude insect‐monitoring radar and ground‐based butterfly monitoring schemes. Here we use V. cardui as a model species to better understand insect migration in the Western Palaearctic, and we capitalise on the complementary data sources available for this iconic butterfly. The migratory cycle in this species involves six generations, encompassing a latitudinal shift of thousands of kilometres (up to 60 degrees of latitude). The cycle comprises an annual poleward advance of the populations in spring followed by an equatorward return movement in autumn, with returning individuals potentially flying thousands of kilometres. We show that many long‐distance migrants take advantage of favourable winds, moving downwind at high elevation (from some tens of metres from the ground to altitudes over 1000 m), pointing at strong similarities in the flight strategies used by V. cardui and other migrant Lepidoptera. Our results reveal the highly successful strategy that has evolved in these insects, and provide a useful framework for a better understanding of long‐distance seasonal migration in the temperate regions worldwide.     

Computational Modeling of Channelrhodopsin-2 Photocurrent Characteristics in Relation to Neural Signaling

Channelrhodopsins-2 (ChR2) are a class of light sensitive proteins that offer the ability to use light stimulation to regulate neural activity with millisecond precision. In order to address the limitations in the efficacy of the wild-type ChR2 (ChRwt) to achieve this objective, new variants of ChR2 that exhibit fast mon-exponential photocurrent decay characteristics have been recently developed and validated. In this paper, we investigate whether the framework of transition rate model with 4 states, primarily developed to mimic the biexponential photocurrent decay kinetics of ChRwt, as opposed to the low complexity 3 state model, is warranted to mimic the mono-exponential photocurrent decay kinetics of the newly developed fast ChR2 variants: ChETA (Gunaydin et al., Nature Neurosci. 13:387–392, 2010) and ChRET/TC (Berndt et al., Proc. Natl. Acad. Sci. 108:7595–7600, 2011). We begin by estimating the parameters of the 3-state and 4-state models from experimental data on the photocurrent kinetics of ChRwt, ChETA, and ChRET/TC. We then incorporate these models into a fast-spiking interneuron model (Wang and Buzsaki, J. Neurosci. 16:6402–6413, 1996) and a hippocampal pyramidal cell model (Golomb et al., J. Neurophysiol. 96:1912–1926, 2006) and investigate the extent to which the experimentally observed neural response to various optostimulation protocols can be captured by these models. We demonstrate that for all ChR2 variants investigated, the 4 state model implementation is better able to capture neural response consistent with experiments across wide range of optostimulation protocol. We conclude by analytically investigating the conditions under which the characteristic specific to the 3-state model, namely the monoexponential photocurrent decay of the newly developed variants of ChR2, can occur in the framework of the 4-state model.     

Biohydrogen production by dark fermentation of glycerol using Enterobacter and Citrobacter Sp

Glycerol is an attractive substrate for biohydrogen production because, in theory, it can produce 3 mol of hydrogen per mol of glycerol. Moreover, glycerol is produced in substantial amounts as a byproduct of producing biodiesel, the demand for which has increased in recent years. Therefore, hydrogen production from glycerol was studied by dark fermentation using three strains of bacteria: namely, Enterobacter spH1, Enterobacter spH2, and Citrobacter freundii H3 and a mixture thereof (1:1:1). It was found that, when an initial concentration of 20 g/L of glycerol was used, all three strains and their mixture produced substantial amounts of hydrogen ranging from 2400 to 3500 mL/L, being highest for C. freundii H3 (3547 mL/L) and Enterobacter spH1 (3506 mL/L). The main nongaseous fermentation products were ethanol and acetate, albeit in different ratios. For Enterobacter spH1, Enterobacter spH2, C. freundii H3, and the mixture (1:1:1), the ethanol yields (in mol EtOH/mol glycerol consumed) were 0.96, 0.67, 0.31, and 0.66, respectively. Compared to the individual strains, the mixture (1:1:1) did not show a significantly higher hydrogen level, indicating that there was no synergistic effect. Enterobacter spH1 was selected for further investigation because of its higher yield of hydrogen and ethanol. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2013     

Recent trends in butterfly populations from north-east Spain and Andorra in the light of habitat and climate change

Although butterfly declines have been reported across Europe, no assessment based on detailed quantitative data has ever been made for any extensive area in the Mediterranean Basin. In 1994, a Butterfly Monitoring Scheme was launched in Catalonia (NE Spain), and in 2005 a similar, albeit much smaller, scheme started in the neighbouring Pyrenean country of Andorra. Here we provide a first thorough assessment of butterfly trends in both areas for the last 15 years. Several patterns emerged, above all a worrying decline of a substantial part of the fauna. It was also evident that habitat specialists are experiencing greater declines than habitat generalists, thereby butterfly communities becoming progressively dominated by common species. However, habitat indicators based on characteristic species also revealed that trends are actually associated with habitat types, grassland and scrub specialists declining strongly but woodland specialists showing a marginal increase. These differences are certainly related to profound landscape changes, mainly a dramatic reduction of semi-natural grasslands and open Mediterranean scrub, and a major increase in woodlands. The general effect of climatic warming on butterfly populations was investigated by using the temperature community index (CTI) approach. The thermal structure of butterfly communities remained very stable over time, except in one case where, contrary to the expectations, a significant negative trend in the CTI was noted. However, this surprising result can be explained by taking into account the above-reported pattern of butterfly communities becoming dominated by common species, characterized by low thermal indices in comparison with declining Mediterranean specialists.     

A novel effect of zinc on the lobster muscle GABA receptor

The effect of zinc (and copper) was investigated on the lobster muscle gamma-aminobutyric acid (GABA) receptor. Zinc (10 microns-1 mM) depressed the GABA-evoked conductance increase in a fully reversible manner by possibly binding to an imidazole group, suggested from pH titration studies on the evoked-chloride conductance. Other transition metal (period 4) divalent cations (up to 500 microM) were inactive in antagonizing GABA responses. Variation of external chloride or anion substitution did not perturb the zinc antagonism; however, decreasing the pH markedly decreased the potency of zinc. A possible explanation for these results is discussed. Although the zinc antagonism resembled that produced by picrotoxinin, combination of these two agents depressed the GABA dose--conductance curve in a manner expected for two antagonists acting on independent sites. The zinc binding site was also discrete from the GABA recognition site; the results are interpreted in terms of a distinct binding site for zinc and H+. The distortion of an agonist dose--response curve by formation of an inactive agonist-divalent cation complex is discussed; however, complexation of GABA did not explain the observed antagonism by zinc. By comparison, zinc had no effect on the GABA responses of rat ganglionic neurons. It is concluded that the zinc binding site, on lobster muscle, may be an important modulatory site for the GABA-evoked chloride conductance.