The complete mitochondrial genome of the bird schistosome Trichobilharzia regenti (Platyhelminthes: Digenea), causative agent of cercarial dermatitis

The complete mitochondrial (mt) genome of the neuropathogenic bird schistosome Trichobilharzia regenti was fully sequenced in order to develop molecular markers for future diagnostic, molecular ecological, population, and phylogenetic studies. The genome was 14,838 bp in length, with a 68.4% AT bias in protein coding regions. A repeat element (3 x 184 bp) between trnV and trnW distinguished a single short noncoding region. As 9 of 14 genera of schistosomes parasitize birds, future characterization of their mt genomes is desirable for species-specific and strain- or population-specific diagnostic markers; this concerns not only the nasal representatives, e.g., T. regenti characterized in this study, but also numerous species within the predominant group of visceral (blood dwelling) bird schistosomes.     

Host density predicts presence of cuckoo parasitism in reed warblers

In some hosts of avian brood parasites, several populations apparently escape parasitism, while others are parasitized. Many migratory specialist brood parasites like common cuckoos, Cuculus canorus , experience a short breeding season, and in order to maintain local parasite populations host densities should be sufficiently high to allow efficient nest search. However, no studies have investigated the possible effect of host density on presence of cuckoo parasitism among populations of a single host species. Here, we investigated possible predictors of common cuckoo parasitism in 16 populations of reed warblers, Acrocephalus scirpaceus , across Europe. In more detail, we quantified the effect of host density, number of host breeding pairs, habitat type, mean distance to nearest cuckoo vantage point, predation rate and latitude on the presence of cuckoo parasitism while controlling for geographical distance among study populations. Host density was a powerful predictor of parasitism. We also found a less pronounced effect of habitat type on occurrence of parasitism, while the other variables did not explain why cuckoos utilize some reed warbler populations and not others. This is the first study focusing on patterns of common cuckoo-host interactions within a specific host species on a large geographic scale. The results indicate that if host density is below a specific threshold, cuckoo parasitism is absent regardless of the state of other potentially confounding variables.     

Ancestral chromosomal blocks are triplicated in Brassiceae species with varying chromosome number and genome size

The paleopolyploid character of genomes of the economically important genus Brassica and closely related species (tribe Brassiceae) is still fairly controversial. Here, we report on the comparative painting analysis of block F of the crucifer Ancestral Karyotype (AK; n = 8), consisting of 24 conserved genomic blocks, in 10 species traditionally treated as members of the tribe Brassiceae. Three homeologous copies of block F were identified per haploid chromosome complement in Brassiceae species with 2n = 14, 18, 20, 32, and 36. In high-polyploid (n >or= 30) species Crambe maritima (2n = 60), Crambe cordifolia (2n = 120), and Vella pseudocytisus (2n = 68), six, 12, and six copies of the analyzed block have been revealed, respectively. Homeologous regions resembled the ancestral structure of block F within the AK or were altered by inversions and/or translocations. In two species of the subtribe Zillineae, two of the three homeologous regions were combined via a reciprocal translocation onto one chromosome. Altogether, these findings provide compelling evidence of an ancient hexaploidization event and corresponding whole-genome triplication shared by the tribe Brassiceae. No direct relationship between chromosome number and genome size variation (1.2-2.5 pg/2C) has been found in Brassiceae species with 2n = 14 to 36. Only two homeologous copies of block F suggest a whole-genome duplication but not the triplication event in Orychophragmus violaceus (2n = 24), and confirm a phylogenetic position of this species outside the tribe Brassiceae. Chromosome duplication detected in Orychophragmus as well as chromosome rearrangements shared by Zillineae species demonstrate the usefulness of comparative cytogenetics for elucidation of phylogenetic relationships.     

Mapping of cytochrome P450 2B4 substrate binding sites by photolabile probe 3-azidiamantane: identification of putative substrate access regions

To investigate structure-function relationships of cytochromes P450 (CYP), 3-azidiamantane was employed for photoaffinity labeling of rabbit microsomal CYP2B4. Four diamantane labeled tryptic fragments were identified by mass spectrometry and sequencing: peptide I (Leu³⁵⁹-Lys³⁷³), peptide II (Leu³⁰-Arg⁴⁸), peptide III (Phe¹²⁷-Arg¹⁴⁰), and peptide IV (Arg⁴³⁴-Arg⁴⁴³). Their positions were projected into CYP2B4 model structures and compared with substrate binding sites, proposed by docking of diamantane. We identified novel binding regions outside the active site of CYP2B4. One of them, defined with diamantane modified Arg¹³³, marks a possible entrance to the active site from the heme proximal face. In addition to crystal structures of CYP2B4 chimeras and molecular dynamics simulations, our data of photoaffinity labeling of the full CYP2B4 molecule provide further insight into functional and structural aspects of substrate binding.     

Divergent location of ribosomal genes in chromosomes of fish thorny-headed worms, <Emphasis Type="Italic">Pomphorhynchus laevis</Emphasis> and <Emphasis Type="Italic">Pomphorhynchus tereticollis</Emphasis> (Acanthocephala)

We studied distribution of ribosomal DNA (rDNA) sequences along with chromosomal location of the nucleolar organizer regions (NORs) in males of two fish parasites, Pomphorhynchus laevis and Pomphorhynchus tereticollis (Acanthocephala). Fluorescence in situ hybridization with 18S rDNA probe identified two clusters of rDNA in each species, but revealed a remarkable difference in their location on chromosomes. In P. laevis, the rDNA-FISH signals were found in long arms of the first chromosome pair and in short arms of the second pair. Whereas in P. tereticollis, rDNA clusters were located in long arms of both the first and second chromosome pairs. The divergent location of rDNA clusters in the chromosome No. 2 supports current classification of P. tereticollis, previously considered a synonym of P. laevis, as a separate species. A possible scenario of the second chromosome rearrangement during karyotype evolution of the two species involves two successive pericentric inversions. In both species, one or two prominent nucleoli were apparent within interphase nuclei stained with either silver nitrate or a fluorescent dye YOYO-1. However, a single large nucleolus was observed in early stages of mitosis and meiosis I regardless the number of rDNA clusters. Nevertheless, two bivalents with silver-stained NORs in diakinesis and two silver-stained sites in early prophase II nuclei indicated that all NORs are active. This means that each Pomphorhynchus NOR generates a nucleolus, but the resulting nucleoli have a strong tendency to associate in a large body.     

Evolution of fitnesses and allele frequencies in a population with spatially heterogeneous selection pressures

The level of gene flow considerably influences the outcome of evolutionary processes in structured populations with spatial heterogeneity in selection pressures; low levels of gene flow may allow local adaptation whereas high levels of gene flow may oppose this process thus preventing the stable maintenance of polymorphism. Indeed, proportions of fitness space that successfully maintain polymorphism are substantially larger in spatially heterogenous populations with lower to moderate levels of gene flow when compared to single-deme models. Nevertheless, the effect of spatial heterogeneity on the evolutionary construction of polymorphism is less clear. We have investigated the levels of polymorphism resulting from a simple two-deme construction model, which incorporates recurrent mutation as well as selection. We further compared fitness properties, stability of equilibria, and frequency distribution patterns emerging from the construction approach and compared these to the static fitness-space approach. The construction model either promotes or constrains the level of polymorphisms, depending on the levels of gene flow. Comparison of the fitness properties resulting from both approaches shows that they maintain variation in different parts of fitness space. The part of fitness space resulting from construction is more stable than that implied by the ahistoric fitness-space approach. Finally, the equilibrium allele-frequency distribution patterns vary substantially with different levels of gene flow, underlining the importance of correctly sampling spatial structure if these patterns are to be used to estimate population-genetic processes.     

Coupling immunomagnetic separation on magnetic beads with matrix-assisted laser desorption ionization-time of flight mass spectrometry for detection of staphylococcal enterotoxin B

The growing importance of mass spectrometry for the identification and characterization of bacterial protein toxins is a consequence of the improved sensitivity and specificity of mass spectrometry-based techniques, especially when these techniques are combined with affinity methods. Here we describe a novel method based on the use of immunoaffinity capture and matrix-assisted laser desorption ionization-time of flight mass spectrometry for selective purification and detection of staphylococcal enterotoxin B (SEB). SEB is a potent bacterial protein toxin responsible for food poisoning, as well as a potential biological warfare agent. Unambiguous detection of SEB at low-nanogram levels in complex matrices is thus an important objective. In this work, an affinity molecular probe was prepared by immobilizing anti-SEB antibody on the surface of para-toluene-sulfonyl-functionalized monodisperse magnetic particles and used to selectively isolate SEB. Immobilization and affinity capture procedures were optimized to maximize the density of anti-SEB immunoglobulin G and the amount of captured SEB, respectively, on the surface of magnetic beads. SEB could be detected directly "on beads" by placing the molecular probe on the matrix-assisted laser desorption ionization target plate or, alternatively, "off beads" after its acidic elution. Application of this method to complex biological matrices was demonstrated by selective detection of SEB present in different matrices, such as cultivation media of Staphylococcus aureus strains and raw milk samples.     

Slowly progressive voluntary-automatic dissociation of facial movements (Foix-Chavany-Marie syndrome)

We describe a case of slowly developing Foix-Chavany-Marie syndrome associated with distinctive bilateral cortical atrophy of frontal lobes in a 59-year old woman. The neurophysiological mechanism and differential diagnosis concerning the unusually slow progression are discussed.     

Consciousness and co-consciousness, binding problem and schizophrenia

At this time is thought that binding of synchronized and distributed activity is crucial for the mechanism of consciousness. There are suggestive findings that disturbances in this feature binding produce disintegration of consciousness in schizophrenia. It leads to disturbances in reflection of the self and dissociated psychic fragments may be experienced as parts of the external world. Disturbances in the feature binding that lead to disintegration in neural communication among some parts of the brain thus seem to be a neurophysiological counterpart of psychological dissociative processes related to stress response and cognitive, affective and neuroendocrine dysregulation.     

A novel adipokinetic peptide in a water boatman (Heteroptera, Corixidae) and its bioanalogue in a saucer bug (Heteroptera, Naucoridae)

The corpora cardiaca (CC) of two water bug species, the water boatman Corixa punctata and the saucer bug Ilyocoris cimicoides, contain a substance that cause hyperlipemia in the migratory locust. The primary sequence of one octapeptide belonging to the adipokinetic hormone (AKH)/red pigment-concentrating hormone (RPCH) family was deduced from the multiple MS(N) electrospray mass data of CC material from each species. Whereas the saucer bug contains the known octapeptide pGlu-Val-Asn-Phe-Ser-Pro-Ser-Trp amide, code-named Anaim-AKH, the water boatman has a novel peptide identified as pGlu-Leu/Ile-Asn-Phe-Ser-Pro-Ser-Trp amide, code-named Corpu-AKH. The ambiguity about the amino acid at position 2, i.e. Leu or Ile, in Corpu-AKH was solved by isolating the peptide in a single-step by reversed-phase HPLC and establishing co-elution with the synthetic peptide containing Leu at position 2. Functionally, the peptides regulate lipid mobilization, as evidenced by an adipokinetic effect after injecting synthetic Anaim-AKH and Corpu-AKH into the respective acceptor species. Swimming activity of I. cimicoides also causes hyperlipemia.