Gramicidin K, a new linear channel-forming gramicidin from Bacillus brevis

A new gramicidin has been isolated from a commercial mixture of gramicidins A, B, and C. This new molecule, designated gramicidin K, contains formyl and ethanolamine blocking groups, has a molecular weight approximately 20% higher than gramicidin A, and is strongly retained on reversed-phase liquid chromatographic columns. Gramicidin K can be resolved into two components, one of which contains tyrosine. In lipid bilayer membranes, both components form channels of considerably longer lifetime and somewhat lower conductance than gramicidin A. Gramicidin K appears to be a lipopeptide that consists of a fatty acyl chain attached to the ethanolamine of gramicidin A.     

Fragmented and scrambled mitochondrial ribosomal RNA coding regions among green algae: a model for their origin and evolution

Mitochondrial ribosomal RNA coding regions in the only three green algal taxa investigated to date are fundamentally different in that they are continuous in Prototheca wickerhamii, but highly fragmented and scrambled in Chlamydomonas reinhardtii and Chlamydomonas eugametos. To gain more insight into the mode of evolution of fragmented and scrambled mitochondrial ribosomal RNA (rRNA) genes within the green algal group, this work (1) provides additional information on fragmentation patterns of mitochondrial small- and large-subunit (SSU and LSU) rRNAs that strongly supports the concept of a gradual increase in the extent of discontinuity of mitochondrial rRNAs among chlorophycean green algae and (2) reports the first example of fragmented and scrambled mitochondrial LSU rRNA coding regions in a green algal taxon outside the Chlamydomonas group. The present study (1) suggests that the scrambling of the mitochondrial rRNA coding regions may have occurred early in the evolution of fragmented and scrambled mitochondrial rRNA genes within the chlorophycean green algal group, most likely in parallel with the fragmentation events, (2) proposes recombination as a possible mechanism involved in the evolution of these mitochondrial rRNA genes, and (3) presents a hypothetical pathway for converting continuous mitochondrial rRNA genes into the highly fragmented and scrambled rRNA coding regions of Chlamydomonas through a series of recombinatorial events between short repeated sequences.      

Large-scale identification of polymorphic microsatellites using an <Emphasis Type="Italic">in silico</Emphasis> approach

Background  

Simple Sequence Repeat (SSR) or microsatellite markers are valuable for genetic research. Experimental methods to develop SSR markers are laborious, time consuming and expensive. In silico approaches have become a practicable and relatively inexpensive alternative during the last decade, although testing putative SSR markers still is time consuming and expensive. In many species only a relatively small percentage of SSR markers turn out to be polymorphic. This is particularly true for markers derived from expressed sequence tags (ESTs). In EST databases a large redundancy of sequences is present, which may contain information on length-polymorphisms in the SSR they contain, and whether they have been derived from heterozygotes or from different genotypes. Up to now, although a number of programs have been developed to identify SSRs in EST sequences, no software can detect putatively polymorphic SSRs.     

Mental practice-based rehabilitation training to improve arm function and daily activity performance in stroke patients: a randomized clinical trial

Background  

Over 50% of patients with upper limb paresis resulting from stroke face long-term impaired arm function and ensuing disability in daily life. Unfortunately, the number of effective treatments aimed at improving arm function due to stroke is still low. This study aims to evaluate a new therapy for improving arm function in sub-acute stroke patients based on mental practice theories and functional task-oriented training, and to study the predictors for a positive treatment result. It is hypothesized that a six-week, mental practice-based training program (additional to regular therapy) targeting the specific upper extremity skills important to the individual patient will significantly improve both arm function and daily activity performance, as well as being cost effective.     

Conformational changes and molecular mobility in plasticized proteins

Most biopolymers exist in a plasticized state, whether it is naturally with water or unnaturally with glycerol or other suitable polyol, to make a flexible material. We have found that the extent to which a biopolymer can be plasticized is dependent on its molecular and higher order structures outside of simply molecular weight. Lactalbumin, ovalbumin, corn zein, wheat gluten, and feather keratin were plasticized with glycerol from very low to very high amounts. The conformation of the proteins was monitored with Fourier transform-infrared (FT-IR) spectroscopy and X-ray powder diffraction (XRD) and correlated with the tensile modulus. Protein conformational changes were pronounced for polar proteins with a low amount of cysteine. FT-IR showed that the conformational changes resulted in ordering of the protein at low to moderate plasticization levels. For proteins with little resistance to conformational changes, additional small-scale ordering occurred around the glass transition, as observed in XRD. Accurate comparison of plasticized proteins was dependent on knowing whether or not the protein was glassy or rubbery at room temperature as no differences arose in the glassy state. The transition from glassy to rubbery behavior with plasticization level can be found from modulus, FT-IR, and XRD data.     

Aglycone exploration of C-arylglucoside inhibitors of renal sodium-dependent glucose transporter SGLT2

Inhibition of sodium-dependent glucose transporter 2 (SGLT2), the transporter that is responsible for renal re-uptake of glucose, leads to glucosuria in animals. SGLT-mediated glucosuria provides a mechanism to shed excess plasma glucose to ameliorate diabetes-related hyperglycemia and associated complications. The current study demonstrates that the proper relationship of a 4′-substituted benzyl group to a β-1C-phenylglucoside is important for potent and selective SGLT2 inhibition. The lead C-arylglucoside (7a) demonstrates superior metabolic stability to its O-arylglucoside counterpart (4) and it promotes glucosuria when administered in vivo.     

Biodiversity of 52 chicken populations assessed by microsatellite typing of DNA pools

In a project on the biodiversity of chickens funded by the European Commission (EC), eight laboratories collaborated to assess the genetic variation within and between 52 populations from a wide range of chicken types. Twenty-two di-nucleotide microsatellite markers were used to genotype DNA pools of 50 birds from each population. The polymorphism measures for the average, the least polymorphic population (inbred C line) and the most polymorphic population (Gallus gallus spadiceus) were, respectively, as follows: number of alleles per locus, per population: 3.5, 1.3 and 5.2; average gene diversity across markers: 0.47, 0.05 and 0.64; and proportion of polymorphic markers: 0.91, 0.25 and 1.0. These were in good agreement with the breeding history of the populations. For instance, unselected populations were found to be more polymorphic than selected breeds such as layers. Thus DNA pools are effective in the preliminary assessment of genetic variation of populations and markers. Mean genetic distance indicates the extent to which a given population shares its genetic diversity with that of the whole tested gene pool and is a useful criterion for conservation of diversity. The distribution of population-specific (private) alleles and the amount of genetic variation shared among populations supports the hypothesis that the red jungle fowl is the main progenitor of the domesticated chicken.     

The genus Teliocrinus (Crinoidea,Echinodermata): a key taxon among pentacrinid stalked crinoids

The main characters of the stalked crinoids of the family Pentacrinitidae attributed to the genus Teliocrinus are re‐evaluated from a quantitative study of phenotype variation, new observations on arm and stalk articulations, and observation of ontogenetic trends. All of the specimens collected in the northern Indian Ocean belong to the same species, i.e. Teliocrinus springeri (Clark, 1909). However, two phenotypes living at different depths remain valid as subspecies: Teliocrinus springeri springeri (Clark, 1909) and Teliocrinus springeri liliaceus (Clark, 1909). Teliocrinus shares several ontogenetic trends with Endoxocrinus, especially in nonfunctional brachial articulations and stalk symplexies. Its assignment to the Diplocrininae is confirmed. A discussion of its affinities with pentacrinid fossil genera in which the crown is well preserved suggests that Diplocrininae could have first appeared during the Lower Cretaceous. A shortening of brachitaxes and a paedomorphic trend of stalk symplexies are the main other evolutionary traits. Nonfunctional articulations are frequently found at the paedomorphic pole of the heterochronic gradient, without clear derived characters. Classification of pentacrinids mainly based on such symplesiomorphy or paedomorphic characters must be definitively abandoned. However, in post‐Palaeozoic stalked crinoids the scarcity of well‐preserved fossils, the high frequency of paedomorphy, and convergent adaptive characters makes phylogenetic reconstruction only based on morphological characters very difficult and speculative. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 155 , 22–39.