MHC genes and parasitism in Carassius gibelio, a diploid-triploid fish species with dual reproduction strategies.

BACKGROUND: The gibel carp is a fish species with dual reproduction modes, gynogenesis and sexual reproduction, coexisting in mixed diploid-polyploid populations. Following the Red Queen (RQ) assumption, asexual organisms are, due to their low genetic diversity, targets for parasite adaptation. Because MHC polymorphism is maintained by selection from parasites and sexual selection, MHC genes are considered as a suitable candidate for testing the RQ hypothesis. In this study, we investigated MHC variability and the selection pressure acting on MHC genes in sexual diploids and asexual triploids. In addition, we tested whether the asexual form of gibel carp suffers from higher parasite loads than the sexual form. RESULTS: At the population level, genotype and allelic diversity of MHC were reduced in gynogenetic triploids when compared to sexual diploids. Different patterns in positively selected sites (PSS) between gynogens and sexual gibel carp were also found. A weak difference in parasite species richness was found between sexual fish and gynogens. However, two common clones of gynogens were significantly more parasitized than sexual diploids or other gynogens with rare MHC genotypes. At the individual level, the higher number of alleles was not associated with higher parasitism in either sexual diploids or gynogens. CONCLUSIONS: The differences in MHC diversity between gynogenetic triploids and sexual diploids are in accordance with the hypothesis of sexually-mediated selection increasing MHC diversity and fulfil a prerequisite of the Red Queen hypothesis. The different patterns in PSS between gynogens and sexual gibel carp also suggest the potential role of sexual selection and supports parasite-mediated selection maintaining MHC diversity. We showed that the most common MHC genotypes of gynogenetic triploids are the target of parasite selection. Our results suggest that the MHC genotype in gibel carp is more important than allelic number for immunocompetence.

Genome-wide architecture of reproductive isolation in a naturally occurring hybrid zone between Mus musculus musculus and M. m. domesticus.

Studies of a hybrid zone between two house mouse subspecies (Mus musculus musculus and M. m. domesticus) along with studies using laboratory crosses reveal a large role for the X chromosome and multiple autosomal regions in reproductive isolation as a consequence of disrupted epistasis in hybrids. One limitation of previous work has been that most of the identified genomic regions have been large. The goal here is to detect and characterize precise genomic regions underlying reproductive isolation. We surveyed 1401 markers evenly spaced across the genome in 679 mice collected from two different transects. Comparisons between transects provide a means for identifying common patterns that likely reflect intrinsic incompatibilities. We used a genomic cline approach to identify patterns that correspond to epistasis. From both transects, we identified contiguous regions on the X chromosome in which markers were inferred to be involved in epistatic interactions. We then searched for autosomal regions showing the same patterns and found they constitute about 5% of autosomal markers. We discovered substantial overlap between these candidate regions underlying reproductive isolation and QTL for hybrid sterility identified in laboratory crosses. Analysis of gene content in these regions suggests a key role for several mechanisms, including the regulation of transcription, sexual conflict and sexual selection operating at both the postmating prezygotic and postzygotic stages of reproductive isolation. Taken together, these results indicate that speciation in two recently diverged (c. 0.5 Ma) house mouse subspecies is complex, involving many genes dispersed throughout the genome and associated with distinct functions.

Measures of linkage disequilibrium among neighbouring SNPs indicate asymmetries across the house mouse hybrid zone.

Theory predicts that naturally occurring hybrid zones between genetically distinct taxa can move over space and time as a result of selection and/or demographic processes, with certain types of hybrid zones being more or less likely to move. Determining whether a hybrid zone is stationary or moving has important implications for understanding evolutionary processes affecting interactions in hybrid populations. However, direct observations of hybrid zone movement are difficult to make unless the zone is moving rapidly. Here, evidence for movement in the house mouse Mus musculus domesticus × Mus musculus musculus hybrid zone is provided using measures of LD and haplotype structure among neighbouring SNP markers from across the genome. Local populations of mice across two transects in Germany and the Czech Republic were sampled, and a total of 1301 mice were genotyped at 1401 markers from the nuclear genome. Empirical measures of LD provide evidence for extinction and (re)colonization in single populations and, together with simulations, suggest hybrid zone movement because of either geography-dependent asymmetrical dispersal or selection favouring one subspecies over the other.

Redescription and resurrection of Bertiella satyri (Cestoda, Anoplocephalidae) parasitizing the orangutan (Pongo abelii) in Indonesia.

The tapeworm species Bertiella satyri from a semi-wild Sumatran orangutan (Pongo abelii: Ponginae) is redescribed and the sequence of its 18S rDNA is presented. The tapeworms parasitizing the genera Pan, Pongo, Homo and Hylobates from Muséum National d'Histoire Naturelle, Paris and from Muséum d´Histoire Naturelle, Genève are also presented. The validity of B. satyri is confirmed. B. satyri (BSA) differs from the most similar species Bertiella studeri (BSTU) in the following characteristics: (1) testes number, BSTU 300-400; BSA 116-124, (2) genital opening, BSTU regularly alternate; BSA irregularly alternate, (3) Cirrus-sac, BSTU short, 0.250-0.320, does not reach excretory ducts; BSA long, 0.630 × 0.495, reaches excretory ducts, (4) egg size, BSTU 0.053-0.060; BSA 0.030-0.051, (5) host BSTU Pan troglodytes, Africa; BSA Pongo pygmaeus, P. abelii, Indonesia (Borneo, Sumatra). Both species differ according to our material and the name B. satyri (Blanchard, 1891) is resurrected.

[KRAS mutation testing in therapeutic algorithm for treatment of metastatic colorectal carcinoma]. / Vysetrení mutacního statutu genu KRAS jako soucást algoritmu lécby metastatického kolorektálního karcinomu.

Targeted therapy has become an integral part of treatment procedures of malignant tumors. Colorectal carcinomas are frequently targeted with monoclonal anti-EGFR antibodies (cetuximab and panitumumab). Activating somatic mutations in codons 12 and 13 of the exon 2 of KRAS gene are considered negative predictive factors of response to anti-EGFR therapy in patients with metastatic colorectal cancer. In the Czech Republic, evaluation of mutational status of KRAS gene is performed in several referral laboratories. In 2009, these laboratories performed 2580 tests of the KRAS mutational status--out of these, 60.2% cases reported non-mutated, wild-type KRAS. In one of the referral laboratories, we demonstrate the logistics of KRAS testing procedure. Stratification of patients with metastatic colorectal tumors based on their KRAS mutational status has evolved to a standard procedure. Laboratories performing these methods shall therefore adhere to the recommendations of the professional and accredited societies.

Molecular phylogeny of monogeneans parasitizing African freshwater Cichlidae inferred from LSU rDNA sequences.

The African freshwater fish of Cichlidae are parasitized by five genera of monogeneans belonging to Dactylogyridea. Ectoparasitic Scutogyrus, Onchobdella, and the highly diversified Cichlidogyrus represent three genera located on the gills, while the endoparasitic Enterogyrus and Urogyrus are located in the stomach and the urinary bladder, respectively. Representatives of four dactylogyridean genera (except for Urogyrus) were collected from seven cichlid species in West Africa. The aim of this study was to investigate the phylogenetic relationships between ectoparasitic and endoparasitic dactylogyridaen monogeneans specific to African freshwater Cichlidae and other representatives of Dactylogyridae, including a wide range of species from both freshwater and marine environments. All phylogenetic analyses point to the polyphyletic origin of the subfamily Ancyrocephalinae. Both Enterogyrus and Onchobdella were found to be monophyletic. The phylogenetic position of Scutogyrus longicornis was placed within the Cichlidogyrus species, which suggests the non-monophyly of Cichlidogyrus. Therefore, we have proposed a taxonomical revision of the species recently considered to be Scutogyrus. However, these four dactylogyridean genera-specific to cichlids do not form a monophyletic group. Using LSU rDNA analyses, we found that Enterogyrus and Onchobdella form a clade with Protogyrodactylus, i.e., the parasite species does not live in cichlids, which suggests that endoparasitism in cichlid monogeneans is not an ancestral feature.

Development of unique house mouse resources suitable for evolutionary studies of speciation.

Two house mouse subspecies, Mus musculus domesticus and Mus musculus musculus, form a hybrid zone in Europe and represent a suitable model for inferring the genes contributing to isolation barriers between parental taxa. Despite long-term intensive studies of this hybrid zone, we still know relatively little about the causes and mechanisms maintaining the 2 taxa as separate subspecies; therefore, to gain insight into this process, we developed 8 wild-derived inbred house mouse strains. In order to produce strains as pure domesticus or musculus genomes as possible, the individuals used to establish the breeding colony for the 3 domesticus and 2 of the musculus strains were captured in the Czech Republic from wild populations at extreme western and eastern edges of the subspecific contact zone, respectively. The remaining 3 musculus strains were bred from mice captured about 250 km east of the hybrid zone. Genetic analysis based on 361 microsatellite loci showed that 82% of these markers are diagnostic for either the musculus or the domesticus strains. In order to demonstrate the potential utility of this genetic differentiation in such strains, phenotypic variation was scored for 2 strains from opposite edges of the hybrid zone and significant differences in morphology, reproductive performance, in vitro immune responses, mate choice based on urinary signals, and aggressiveness were found. In addition, the 3 strains derived from musculus populations far from the hybrid zone display significant differences in polymorphism in hybrid male sterility when crossed with the laboratory strains C57BL/6 or C57BL/10, which have a predominantly domesticus genome. Although further studies will be necessary to demonstrate intersubspecific differences, all analyses presented here indicate that these newly developed house mouse strains represent a powerful tool for elucidating the genetic basis of isolation barriers in hybrid zones and for studying speciation in general.

Five novel mutations in the C1 inhibitor gene (C1NH) leading to a premature stop codon in patients with type I hereditary angioedema.

Hereditary angioedema (HAE) is a disorder characterised by recurrent attacks of localized subcutaneous or submucosal edema. It is inherited in an autosomal dominant fashion and caused by a deficiency of C1 inhibitor (C1 inh, or C1NH). Most patients with HAE have an absolute deficiency of C1 inh (type I HAE) while the rest (15% of kindreds) synthetize a dysfunctional C1 inh protein (type II HAE). In this report a novel use of denaturing gradient gel electrophoresis (DGGE) followed by direct sequencing of the C1 inhibitor gene is presented. Five novel mutations, one nonsense (p.S48X) and four small deletions resulting in frameshifts (g.2264-2265delAG, g.2304delC, g.8493-8494delCC and g.16676-16677delTG) have been identified in the C1 inhibitor gene in five families with type I HAE. All of these mutations lead to premature termination of translation and thus can be considered causative of the C1 inh deficiency. Moreover, two previously described mutations in the reactive center of C1 inh, p.R444C and p.R444H, have been detected in four unrelated patients with type II HAE.

Exon 1 polymorphism of the B2BKR gene does not influence the clinical status of patients with hereditary angioedema.

Polymorphic variants of B2 receptors for bradykinin (B2BKR) have been postulated to influence a clinical manifestation of hereditary angioedema. In this study, exon 1 nonanucleotide deletion polymorphism in the B2BKR gene was examined in 37 patients with hereditary angioedema. The patients were grouped according to disease severity or the age of the first clinical manifestation of disease. No significant differences in allelic frequencies were found between particular subgroups of patients. Therefore, we concluded that this polymorphism does not seem to have any significant effect on the course and severity of hereditary angioedema in Caucasians.

Sleep apnea prevalence in acute myocardial infarction--the Sleep Apnea in Post-acute Myocardial Infarction Patients (SAPAMI) Study.

BACKGROUND: While sleep apnea (SA) might be a modifiable cardiovascular risk factor, recent data suggest that SA is severely underdiagnosed in patients after acute myocardial infarction (MI). There is limited evidence about day-night variation of onset of MI on dependence of having SA. We therefore investigated the prevalence of SA and examined the day-night variation of onset of MI in acute MI patients. METHODS: We prospectively studied 782 consecutive patients admitted to the hospital with the diagnosis of acute MI. All subjects underwent sleep evaluations using a portable device after at least 48 h post-admission. Using the apnea-hypopnea index (AHI), groups were defined as patients without SA (<5 events/h), mild SA (5-15 events/h), moderate SA (15-30 events/h), and severe SA (≥ 30 events/h). RESULTS: Almost all patients (98%) underwent urgent coronary angiography and 91% of patients underwent primary PCI. Using a threshold of AHI ≥ 5 events/h, SA was present in 65.7% of patients after acute MI. Mild SA was present in 32.6%, moderate in 20.4% and severe in 12.7%. The day-night variation in the onset of MI in all groups of SA patients was similar to that observed in non-SA patients. From 6 AM to 12 PM, the frequency of MI was higher in both SA and non-SA patients, as compared to the interval from 12 AM to 6 AM (all p<0.05). CONCLUSION: There is a high prevalence of SA in patients presenting with acute MI. Peak time of MI onset in SA patients was between 6 AM and noon, similar to that in the general population. Whether diagnosis and treatment of SA after MI will significantly improve outcomes in these patients remains to be determined.

Polymorphism in hybrid male sterility in wild-derived Mus musculus musculus strains on proximal chromosome 17.

The hybrid sterility-1 (Hst1) locus at Chr 17 causes male sterility in crosses between the house mouse subspecies Mus musculus domesticus (Mmd) and M. m. musculus (Mmm). This locus has been defined by its polymorphic variants in two laboratory strains (Mmd genome) when mated to PWD/Ph mice (Mmm genome): C57BL/10 (carrying the sterile allele) and C3H (fertile allele). The occurrence of sterile and/or fertile (wild Mmm x C57BL)F1 males is evidence that polymorphism for this trait also exists in natural populations of Mmm; however, the nature of this polymorphism remains unclear. Therefore, we derived two wild-origin Mmm strains, STUS and STUF, that produce sterile and fertile males, respectively, in crosses with C57BL mice. To determine the genetic basis underlying male fertility, the (STUS x STUF)F1 females were mated to C57BL/10 J males. About one-third of resulting hybrid males (33.8%) had a significantly smaller epididymis and testes than parental animals and lacked spermatozoa due to meiotic arrest. A further one-fifth of males (20.3%) also had anomalous reproductive traits but produced some spermatozoa. The remaining fertile males (45.9%) displayed no deviation from values found in parental individuals. QTL analysis of the progeny revealed strong associations of male fitness components with the proximal end of Chr 17, and a significant effect of the central section of Chr X on testes mass. The data suggest that genetic incompatibilities associated with male sterility have evolved independently at the proximal end of Chr 17 and are polymorphic within both Mmd and Mmm genomes.

Highly variable patterns of antimicrobial resistance in commensal Escherichia coli isolates from pigs, sympatric rodents, and flies.

Antimicrobial-resistant Escherichia coli strains from pigs, sympatric rodents, and flies from two large farms in the Czech Republic with different antibiotic exposure histories were characterized based on antimicrobial resistance genes, integrons, and macrorestriction DNA profiles. Isolates of E. coli were tested for susceptibility to 12 antimicrobial agents according to the standard disk diffusion method. In resistant isolates, polymerase chain reaction was used to detect antibiotic resistance genes, integrase genes, and gene cassettes. Pulsed-field gel electrophoresis (PFGE) was used for molecular subtyping of E. coli. In farm A (long-term use of amoxicillin only), 75% (n = 198), 65% (n = 49), 11% (n = 139), and 82% (n = 177) of E. coli isolates from piglets, sows, sympatric rodents, and flies, respectively, were antibiotic resistant. In farm B (various antibiotics commonly used), 53% (n = 154), 69% (n = 98), and 54% (n = 74) of E. coli isolates from piglets, sows, and sympatric rodents, respectively, were antibiotic resistant. In both farms, the highest resistance prevalence was to tetracycline, and resistance patterns of isolates were greatly variable. Isolates with the same resistance phenotype, genes, and PFGE profile were found in pigs and flies. Isolates from rodents showed unique PFGE profiles. Close contact of sympatric rodents and flies with pigs or their products was associated with colonization of rodents and flies with resistant bacteria or transfer of resistance genes found in pig intestinal flora.