The presence and polymorphism of genes encoding serine protease autotransporters (spate) among the Escherichia coli isolated in the region of Gdansk from children with diarrhea

The group of 96 strains ofEscherichia coli isolated from children with diarrhea were investigated towards the presence and polymorphism of genes encoding autotransporters that belong to the group of proteins named SPATE (Serine Protease Autotransporters ofEnterobacteriaceae). Based on the results of restriction analysis of the products of PCR reaction 8 different types of genes encoding SPATE were detected. It was found that 39 strains contained one gene of SPATE, 15 strains contained two different genes and 3 different genes were detected in the case of 3 strains. The analysis of combination of presence of genes encoding SPATE let us divide the investigated group of strains into 17 different genotypes. The analysis of polymorphism of genes encoding SPATE seems to be very promising tool for exploring the genetic diversity among pathogenic E. coli.     

Invasive pulmonary aspergillosis due to a mixed infection caused by Aspergillus flavus and Aspergillus fumigatus

Invasive pulmonary aspergillosis is typically caused by a single Aspergillus species, most frequently Aspergillus fumigatus. Here we report that a lung transplant recipient developed invasive aspergillosis due to a mixed infection caused by Aspergillus flavus and A. fumigatus. The implications for this unusual finding are discussed.     

The Effect of Double – Blind Carbohydrate Ingestion during 60 km of Self-Paced Exercise in Warm Ambient Conditions

This study evaluated double blind ingestions of placebo (PLA) versus 6% carbohydrate (CHO) either as capsules (c) or beverage (b) during 60 km self-paced cycling in the heat (32°C and 50% relative humidity). Ten well-trained males (mean ± SD: 26±3 years; 64.5±7.7 kg and 70.7±8.8 ml.kg⁻¹.min⁻¹ maximal oxygen consumption) completed four separate 60 km time trials (TT) punctuated by 1 km sprints (14, 29, 44, 59 km) whilst ingesting either PLA_b or PLA_c or CHO_b or CHO_c. The TT was not different among treatments (PLA_b 130.2±11.2 min, CHO_b 140.5±18.1 min, PLA_c 143.1±29.2 min, CHO_c 137.3±20.1 min; P>0.05). Effect size (Cohen’s d) for time was only moderate when comparing CHO_b – PLA_b (d = 0.68) and PLA_b – PLA_c (d = 0.57) whereas all other ES were ‘trivial’ to ‘small’. Mean speed throughout the trial was significantly higher for PLA_b only (P<0.05). Power output was only different (P<0.05) between the sprints and low intensity efforts within and across conditions. Core and mean skin temperatures were similar among trials. We conclude that CHO ingestion is of little or no benefit as a beverage compared with placebo during 60 km TT in the heat.     

Experimental evidence of habitat selection and territoriality in the Amazonian whip spider Heterophrynus longicornis (Arachnida, Amblypygi)

Animals that select and defend suitable habitats against conspecifics may be favored by maximizing prey encounter rate, gaining protection, or securing matings. However, the identification of habitat selection and territoriality may be hindered in observational studies in sedentary species with low-density populations, such as the whip spider Heterophrynus longicornis. To circumvent such difficulties, we adopted an experimental field approach to evaluate if H. longicornis selects and defends habitat in Central Amazon. To evaluate whether individuals perform habitat selection, we monitored the permanence of 29 experimentally released individuals in buttressed trees with a wide variation in diameter at breast height (DBH), with and without burrows at their bases. To evaluate whether individuals are territorial, we experimentally removed 21 individuals from their previously occupied trees and monitored the recolonization of these trees. If H. longicornis were territorial, we predicted that the recolonizers would be smaller than the removed individuals. We found 12 individuals in the trees where they were released on subsequent days, none of them in trees without burrows. The individual permanence was related to the presence of burrows, and not to DBH. There was recolonization by smaller males and females on ten trees from which the amblypygids were removed. In combination, the permanence of individuals in trees with burrows, the rapid recolonization of experimentally vacated trees by smaller individuals, and the preponderance of one individual per tree, suggest that both male and female H. longicornis perform habitat selection and also that after selecting a site, they defend it against conspecifics.     

Linkage disequilibrium, mutational analysis and natural selection in the repetitive region of the clock gene, period, in Drosophila melanogaster

We have used the method of disequilibrium pattern analysis to examine associations between the threonine-glycine (Thr-Gly) encoding repeat region of the clock gene period (per) of Drosophila melanogaster, and polymorphic sites both upstream and downstream of the repeat, in a number of European fly populations. The results are consistent with the view that selection may be operating on various haplotypes which share the Thr-Gly length alleles encoding 17, 20 and 23 dipeptide pairs, and that the repeat itself may be the focus for selection. These conclusions lend support to a number of other population and behavioural investigations which have provided evidence that selection is acting on the Thr-Gly region. The linkage analysis was also used to infer an approximate mutation rate (mu) for the repeat, of 10(-5) < mu < 4 x 10(-5) per gamete per generation. Direct measurements of the mutation rate using the polymerase chain reaction in a pedigree analysis of tens of thousands of individuals do not contradict this value. Consequently, the Thr-Gly repeat does not have a mutation rate that is as high as some of the non-coding minisatellites, but it is several orders of magnitude higher than the nucleotide substitution rate. The implications of this elevated mutation rate for linkage disequilibria and selection are discussed.     

Do reproductive characteristics of the species explain differences in the investment in weapon size present in males?

Sexually selected traits, such as male weapons, are highly variable in shape and size across species. However, little is known about the mechanisms that may govern this variation. Because males with greater investment in weapon size tend to win more fights, but also pay higher costs related to weapon development and maintenance, larger weapons should be expected only in species in which victory in male–male fights generate reproductive benefits that outweigh investment costs. Here, we hypothesized that the reproductive characteristics that increase the chances of winners to access females or to fertilize eggs will favor the evolution of larger weapons. To evaluate this hypothesis, we conducted a meta-analysis using arthropods as model organisms. To measure investment in weapon size, we gathered both Pearson correlation coefficient and the standardized (but non centralized) slope values for the relationship between weapon size and body size. We found that none of the reproductive characteristics we investigated was related to male weapon size. Thus, it seems that greater certainty of accessing a female or fertilizing female eggs with a victory does not modulate the investment in male weapon size. Perhaps the cost–benefit ratio between weapon size investment and reproductive success is not the main factor driving the variation in weapon size.     

Structural evidence for ligand specificity in the binding domain of the human androgen receptor. Implications for pathogenic gene mutations

The crystal structures of the human androgen receptor (hAR) and human progesterone receptor ligand-binding domains in complex with the same ligand metribolone (R1881) have been determined. Both three-dimensional structures show the typical nuclear receptor fold. The change of two residues in the ligand-binding pocket between the human progesterone receptor and hAR is most likely the source for the specificity of R1881 to the hAR. The structural implications of the 14 known mutations in the ligand-binding pocket of the hAR ligand-binding domains associated with either prostate cancer or the partial or complete androgen receptor insensitivity syndrome were analyzed. The effects of most of these mutants could be explained on the basis of the crystal structure.     

Genomic Organization and Evolution of Alternative Exons in a Drosophila Calcium Channel Gene

The genomic organization of a gene coding for an α1 subunit of a voltage-gated calcium channel of Drosophila melanogaster (Dmca1A) was determined. Thirty-four exons, distributed over 45 kb of genomic sequence, have been identified and mapped, including exons in three regions involved in alternative splicing and new sites potentially involved in RNA editing. The comparison of the intron/exon boundaries of this channel with a mammalian counterpart shows that the genomic structure of these two genes has remained fairly similar during evolution, with more than half of the Drosophila intron positions being perfectly conserved compared to the human channel. Phylogenetic analysis of the mutually exclusive alternative exons revealed that they have diverged considerably. It is suggested that this divergence, rather than reflecting evolutionary age, is the likely result of accelerated rates of evolution following duplication.