Exploration of environmental changes relates to lifestyle

Decision making in informed animals is often described by optimalitymodels. However, how information about an environment is acquiredis rarely investigated. Cost/benefit considerations suggestthat species differ in this respect according to their lifestyle.We tested the hypothesis that resident species react to changesin their familiar environment earlier and explore it more intensivelythan do nomadic species by observing the response to environmentalchanges (presentation of novel objects) in 10 parrot species.Phylogenetic relationships were taken into account. Residentstouched the novel objects significantly earlier and exploredmore objects than did nomads. In addition, species with a highproportion of fruits in their food spectrum explored more thandid species with other food preferences. The results are inaccordance with different costs and benefits of informationgathering for species that differ in their lifestyle and ecologicaldemands.     

The extended Moran effect and large-scale synchronous fluctuations in the size of great tit and blue tit populations

1. Synchronous fluctuations of geographically separated populations are in general explained by the Moran effect, i.e. a common influence on the local population dynamics of environmental variables that are correlated in space. Empirical support for such a Moran effect has been difficult to provide, mainly due to problems separating out effects of local population dynamics, demographic stochasticity and dispersal that also influence the spatial scaling of population processes. Here we generalize the Moran effect by decomposing the spatial autocorrelation function for fluctuations in the size of great tit Parus major and blue tit Cyanistes caeruleus populations into components due to spatial correlations in the environmental noise, local differences in the strength of density regulation and the effects of demographic stochasticity. 2. Differences between localities in the strength of density dependence and nonlinearity in the density regulation had a small effect on population synchrony, whereas demographic stochasticity reduced the effects of the spatial correlation in environmental noise on the spatial correlations in population size by 21.7% and 23.3% in the great tit and blue tit, respectively. 3. Different environmental variables, such as beech mast and climate, induce a common environmental forcing on the dynamics of central European great and blue tit populations. This generates synchronous fluctuations in the size of populations located several hundred kilometres apart. 4. Although these environmental variables were autocorrelated over large areas, their contribution to the spatial synchrony in the population fluctuations differed, dependent on the spatial scaling of their effects on the local population dynamics. We also demonstrate that this effect can lead to the paradoxical result that a common environmental variable can induce spatial desynchronization of the population fluctuations. 5. This demonstrates that a proper understanding of the ecological consequences of environmental changes, especially those that occur simultaneously over large areas, will require information about the spatial scaling of their effects on local population dynamics.     

Cyclic neoglycodecapeptides: how to increase their inhibitory activity and selectivity on lectin/toxin binding to a glycoprotein and cells

Protein (lectin/toxin)–glycan interaction can be clinically harmful so that the design of inhibitors has become an aim. Cyclic decapeptides are suited as rigid carriers for carbohydrate derivatives. We herein document the bioactivity of sugar headgroups covalently attached to this carrier for the cases of five proteins, i.e. a potent biohazardous plant agglutinin, a leguminous model lectin and three adhesion/growth‐regulatory human lectins. They represent the different types of topological organization within the galectin family. The relative inhibitory activities of glycoclusters with the three ligands (galactose, lactose and the disaccharide of the Thomsen‐Friedenreich antigen) reflected the affinity of free carbohydrates, hereby excluding an impairment of binding activity by chemical derivatization and conjugation. Headgroup tailoring is thus one route to optimize activity and selectivity of cyclopeptide‐based glycoclusters. The increase of ligand density from tetra‐ to hexadecavalency added a second route. The plant toxin and tandem‐repeat‐type galectin‐4 were especially sensitive to this parameter change. Strategically combining solid‐phase assays for screening with analysis of lectin binding to cells in different systems revealed efficient inhibition by distinct glycoclusters, thereby protecting cells from lectin association. Cyclic neoglycodecapeptides thus warrant further study as lectin‐directed pharmaceuticals. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.     

Risk stratification by residual enzyme activity after newborn screening for medium-chain acyl-CoA dehyrogenase deficiency: Data from a cohort study

ABSTRACT: BACKGROUND: Since the introduction of medium-chain acyl coenzyme A dehydrogenase (MCAD) deficiency in population newborn bloodspot screening (NBS) programs, subjects have been identified with variant ACADM (gene encoding MCAD enzyme) genotypes that have never been identified in clinically ascertained patients. It could be hypothesised that residual MCAD enzyme activity can contribute in risk stratification of subjects with variant ACADM genotypes. METHODS: We performed a retrospective cohort study of all patients identified upon population NBS for MCAD deficiency in the Netherlands between 2007-2010. Clinical, molecular, and enzymatic data were integrated. RESULTS: Eighty-four patients from 76 families were identified. Twenty-two percent of the subjects had a variant ACADM genotype. In patients with classical ACADM genotypes, residual MCAD enzyme activity was significantly lower (median 0%, range 0-8%) when compared to subjects with variant ACADM genotypes (range 0-63%; 4 cases with 0%, remainder 20-63%). Patients with (fatal) neonatal presentations before diagnosis displayed residual MCAD enzyme activities <1%. After diagnosis and initiation of treatment, residual MCAD enzyme activities <10% were associated with an increased risk of hypoglycaemia and carnitine supplementation. The prevalence of MCAD deficiency upon screening was 1/8,750 (95% CI 1/7,210-1/11,130). CONCLUSIONS: Determination of residual MCAD enzyme activity improves our understanding of variant ACADM genotypes and may contribute to risk stratification. Subjects with variant ACADM genotypes and residual MCAD enzyme activities <10% should be considered to have the same risks as patients with classical ACADM genotypes. Parental instructions and an emergency regimen will remain principles of the treatment in any type of MCAD deficiency, as the effect of intercurrent illness on residual MCAD enzyme activity remains uncertain. There are, however, arguments in favour of abandoning the general advice to avoid prolonged fasting in subjects with variant ACADM genotypes and 10% residual MCAD enzyme activity.     

Internodal elongation and orientation of cellulose microfibrils and microtubules in deepwater rice

Excised stem sections of deepwater rice (Oryza sativa L.) containing the highest internode were used to study the induction of rapid internodal elongation by gibberellin (GA). It has been shown before that this growth response is based on enhanced cell division in the intercalary meristem and on increased cell elongation. In both GA-treated and control stem sections, the basal 5-mm region of the highest internode grows at the fastest rate. During 24 h of GA treatment, the internodal elongation zone expands from 15 to 35 mm. Gibberellin does not promote elongation of internodes from which the intercalary meristem has been excised. The orientation of cellulose microfibrils (CMFs) is a determining factor in cell growth. Elongation is favored when CMFs are oriented transversely to the direction of growth while elongation is limited when CMFs are oriented in the oblique or longitudinal direction. The orientation of CMFs in parenchymal cells of GA-treated and control internodes is transverse throughout the internode, indicating that CMFs do not restrict elongation of these cells. Changes in CMF orientation were observed in epidermal cells, however. In the basal 5-mm zone of the internode, which includes the intercalary meristem, CMFs of the epidermal cell walls are transversely oriented in both GA-treated and control stem sections. In slowly growing control internodes, CMF orientation changes to the oblique as cells are displaced from this basal 5-mm zone to the region above it. In GA-treated rapidly growing internodes, the reorientation of CMFs from the transverse to the oblique is more gradual and extends over the 35-mm length of the elongation zone. The CMFs of older epidermal cells are obliquely oriented in control and GA-treated internodes. The orientation of the CMFs parallels that of the cortical microtubules. This is consistent with the hypothesis that cortical microtubules determine the direction of CMF deposition. We conclude that GA acts on cells that have transversely oriented CMFs but does not promote growth of cells whose CMFs are already obliquely oriented at the start of GA treatment.     

16S rDNA diversity of cultured and uncultured prokaryotes of a mat sample from Lake Fryxell, McMurdo Dry Valleys, Antarctica

The prokaryotic diversity of aerobic and anaerobic bacterial isolates and of bacterial and archaeal 16S rDNA clones was determined for a microbial mat sample from the moated region of Lake Fryxell, McMurdo Dry Valleys, Antarctica. Among the anaerobic bacteria, members of Clostridium estertheticum and some other psychrotolerant strains dominated whereas methanogens and other Archaea were lacking. Isolates highly related to Flavobacterium hibernum, Janthiniobacterium lividum, and Arthrobacter flavus were among the aerobic bacteria most frequently isolated. Assessment of more than 350 partial 16S rDNA clone sequences of libraries generated by Bacteria- and Archaea-specific PCR primers revealed a rich spectrum of bacterial diversity but only two different archaeal clone sequences. Among the Bacteria, representative sequences belonged to the class Proteobacteria, order Verrucomicrobiales, class Actinobacteria, Clostridium/Bacillus subphylum of Gram-positives, and the Cytophaga-Flavobacterium-Bacteroides phylum. The clones formed about 70 higher taxonomy groups (<98% sequence similarity) and 133 potential species, i.e., groups of clones sharing greater than 98% similarity. Only rarely were clone sequences found to be highly related to Lake Fryxell isolates and to strains of described species. Subsequent analysis of ten sequencing batches of 36 individual clones indicated that the diversity might be still higher than had been assessed.     

Call to consolidate achievements for onchocerciasis and lymphatic filariasis control

The Bernhard Nocht Institute for Tropical Medicine and the UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases held an international conference to review recent achievements in research and control of onchocerciasis and lymphatic filariasis on 19-23 September 2001 in Hamburg, Germany.