Jaroslav Pialek
@ivb.cz
Institute of Vertebrate Biology
Czech Academy of Sciences
RESEARCH INTERESTS
Genetics of sterility
wild-derived strains
house mouse
hybrid zone
Scopus Publications
Scopus Publications
Dagmar Čížková, Lucie Schmiedová, Martin Kváč, Bohumil Sak, Miloš Macholán, Jaroslav Piálek, and Jakub Kreisinger
Wiley
AbstractThe question of how interactions between the gut microbiome and vertebrate hosts contribute to host adaptation and speciation is one of the major problems in current evolutionary research. Using bacteriome and mycobiome metabarcoding, we examined how these two components of the gut microbiota vary with the degree of host admixture in secondary contact between two house mouse subspecies (Mus musculus musculus and M. m. domesticus). We used a large data set collected at two replicates of the hybrid zone and model‐based statistical analyses to ensure the robustness of our results. Assuming that the microbiota of wild hosts suffers from spatial autocorrelation, we directly compared the results of statistical models that were spatially naive with those that accounted for spatial autocorrelation. We showed that neglecting spatial autocorrelation can strongly affect the results and lead to misleading conclusions. The spatial analyses showed little difference between subspecies, both in microbiome composition and in individual bacterial lineages. Similarly, the degree of admixture had minimal effects on the gut bacteriome and mycobiome and was caused by changes in a few microbial lineages that correspond to the common symbionts of free‐living house mice. In contrast to previous studies, these data do not support the hypothesis that the microbiota plays an important role in host reproductive isolation in this particular model system.
Romana Stopková, Tereza Matějková, Alica Dodoková, Pavel Talacko, Petr Zacek, Radislav Sedlacek, Jaroslav Piálek, and Pavel Stopka
Springer Science and Business Media LLC
AbstractIn most mammals and particularly in mice, chemical communication relies on the detection of ethologically relevant fitness-related cues from other individuals. In mice, urine is the primary source of these signals, so we employed proteomics and metabolomics to identify key components of chemical signalling. We show that there is a correspondence between urinary volatiles and proteins in the representation of genetic background, sex and environment in two house mouse subspecies Mus musculus musculus and M. m. domesticus. We found that environment has a strong influence upon proteomic and metabolomic variation and that volatile mixtures better represent males while females have surprisingly more sex-biased proteins. Using machine learning and combined-omics techniques, we identified mixtures of metabolites and proteins that are associated with biological features.
Stuart J E Baird, Zuzana Hiadlovská, Kristina Daniszová, Jaroslav Piálek, and Miloš Macholán
Oxford University Press (OUP)
AbstractA remarkable gene copy number (CN) arms race system has recently been described in laboratory mice, where Slx;Slxl1 and Sly genes compete over transmission by altering the fertilization success of X and Y chromosome-bearing sperm, respectively. Here, we focus on this system in nature, where natural selection can counter CN/gene product escalation. Our model is house mouse subspecies hybridizing in Europe. In some regions, Y chromosomes of the Eastern subspecies have introgressed onto Western genomic backgrounds, accompanied by sex ratio distortion in favor of males, consistent with the inbred lines suggested mechanism: Overabundance of SLY protein expressed by invading Y chromosomes. We take Slx as representative of the X side of this arms race and measure Slx|Sly CN and expression across an “Invasion” transect where Ys introgress and a “Control” transect with negligible introgression. Since we found similar Slx|Sly ratios in both transects, SLY overabundance is unlikely to explain the introgression. However, Slx CN is relatively low in the introgression area, suggesting that Slx is less able to combat Sly effects here. Furthermore, deterministic changes in Slx;Sly expression proportions versus CN proportions suggest standing variation for trans regulation of Slx|Sly is being co-opted in nature where their arms race reduces population fitness.
Ming Liu, Caixia Yu, Zhichao Zhang, Mingjing Song, Xiuping Sun, Jaroslav Piálek, Jens Jacob, Jiqi Lu, Lin Cong, Hongmao Zhang,et al.
Springer Science and Business Media LLC
Abstract Background The laboratory mouse was domesticated from the wild house mouse. Understanding the genetics underlying domestication in laboratory mice, especially in the widely used classical inbred mice, is vital for studies using mouse models. However, the genetic mechanism of laboratory mouse domestication remains unknown due to lack of adequate genomic sequences of wild mice. Results We analyze the genetic relationships by whole-genome resequencing of 36 wild mice and 36 inbred strains. All classical inbred mice cluster together distinctly from wild and wild-derived inbred mice. Using nucleotide diversity analysis, Fst, and XP-CLR, we identify 339 positively selected genes that are closely associated with nervous system function. Approximately one third of these positively selected genes are highly expressed in brain tissues, and genetic mouse models of 125 genes in the positively selected genes exhibit abnormal behavioral or nervous system phenotypes. These positively selected genes show a higher ratio of differential expression between wild and classical inbred mice compared with all genes, especially in the hippocampus and frontal lobe. Using a mutant mouse model, we find that the SNP rs27900929 (T>C) in gene Astn2 significantly reduces the tameness of mice and modifies the ratio of the two Astn2 (a/b) isoforms. Conclusion Our study indicates that classical inbred mice experienced high selection pressure during domestication under laboratory conditions. The analysis shows the positively selected genes are closely associated with behavior and the nervous system in mice. Tameness may be related to the Astn2 mutation and regulated by the ratio of the two Astn2 (a/b) isoforms.
Barbora Bendová, Ondřej Mikula, Barbora Vošlajerová Bímová, Dagmar Čížková, Kristina Daniszová, Ľudovít Ďureje, Zuzana Hiadlovská, Miloš Macholán, Jean-Francois Martin, Jaroslav Piálek,et al.
Oxford University Press (OUP)
Abstract The gastrointestinal microbiota (GM) is considered an important component of the vertebrate holobiont. GM–host interactions influence the fitness of holobionts and are, therefore, an integral part of evolution. The house mouse is a prominent model for GM–host interactions, and evidence suggests a role for GM in mouse speciation. However, previous studies based on short 16S rRNA GM profiles of wild house mouse subspecies failed to detect GM divergence, which is a prerequisite for the inclusion of GM in Dobzhansky–Muller incompatibilities. Here, we used standard 16S rRNA GM profiling in two mouse subspecies, Mus musculus musculus and M. m. domesticus, including the intestinal mucosa and content of three gut sections (ileum, caecum, and colon). We reduced environmental variability by sampling GM in the offspring of wild mice bred under seminatural conditions. Although the breeding conditions allowed a contact between the subspecies, we found a clear differentiation of GM between them, in all three gut sections. Differentiation was mainly driven by several Helicobacters and two H. ganmani variants showed a signal of codivergence with their hosts. Helicobacters represent promising candidates for studying GM–host coadaptations and the fitness effects of their interactions.
Alena Fornůsková, Zuzana Hiadlovská, Miloš Macholán, Jaroslav Piálek, and Joëlle Goüy de Bellocq
Centers for Disease Control and Prevention (CDC)
Lymphocytic choriomeningitis virus (LCMV) is an Old World mammarenavirus found worldwide because of its association with the house mouse. When LCMV spills over to immunocompetent humans, the virus can cause aseptic meningitis; in immunocompromised persons, systemic infection and death can occur. Central Europe is a strategic location for the study of LCMV evolutionary history and host specificity because of the presence of a hybrid zone (genetic barrier) between 2 house mouse subspecies, Mus musculus musculus and M. musculus domesticus. We report LCMV prevalence in natural mouse populations from a Czech Republic–Germany transect and genomic characterization of 2 new LCMV variants from the Czech Republic. We demonstrate that the main division in the LCMV phylogenetic tree corresponds to mouse host subspecies and, when the virus is found in human hosts, the mouse subspecies found at the spillover location. Therefore, LCMV strains infecting humans can be predicted by the genetic structure of house mice.
Dagmar Čížková, Ľudovít Ďureje, Jaroslav Piálek, and Jakub Kreisinger
Springer Science and Business Media LLC
Data on the gut microbiota (GM) of wild animals are key to studies on evolutionary biology (host-GM interactions under natural selection), ecology and conservation biology (GM as a fitness component closely connected to the environment). Wildlife GM sampling often requires non-invasive techniques or sampling from dead animals. In a controlled experiment profiling microbial 16S rRNA in 52 house mice (Mus musculus) from eight families and four genetic backgrounds, we studied the effects of live- and snap-trapping on small mammal GM and evaluated the suitability of microbiota from non-fresh faeces as a proxy for caecal GM. We compared CM from individuals sampled 16-18 h after death with those in live traps and caged controls, and caecal and faecal GM collected from mice in live-traps. Sampling delay did not affect GM composition, validating data from fresh cadavers or snap-trapped animals. Animals trapped overnight displayed a slight but significant difference in GM composition to the caged controls, though the change only had negligible effect on GM diversity, composition and inter-individual divergence. Hence, the trapping process appears not to bias GM profiling. Despite their significant difference, caecal and faecal microbiota were correlated in composition and, to a lesser extent, diversity. Both showed congruent patterns of inter-individual divergence following the natural structure of the dataset. Thus, the faecal microbiome represents a good non-invasive proxy of the caecal microbiome, making it suitable for detecting biologically relevant patterns. However, care should be taken when analysing mixed datasets containing both faecal and caecal samples.
Amisa Mukaj, Jaroslav Piálek, Vladana Fotopulosova, Andrew Parker Morgan, Linda Odenthal-Hesse, Emil D Parvanov, and Jiri Forejt
Oxford University Press (OUP)
AbstractThe classical definition posits hybrid sterility as a phenomenon when two parental taxa each of which is fertile produce a hybrid that is sterile. The first hybrid sterility gene in vertebrates, Prdm9, coding for a histone methyltransferase, was identified in crosses between two laboratory mouse strains derived from Mus mus musculus and M. m. domesticus subspecies. The unique function of PRDM9 protein in the initiation of meiotic recombination led to the discovery of the basic molecular mechanism of hybrid sterility in laboratory crosses. However, the role of this protein as a component of reproductive barrier outside the laboratory model remained unclear. Here, we show that the Prdm9 allelic incompatibilities represent the primary cause of reduced fertility in intersubspecific hybrids between M. m. musculus and M. m. domesticus including 16 musculus and domesticus wild-derived strains. Disruption of fertility phenotypes correlated with the rate of failure of synapsis between homologous chromosomes in meiosis I and with early meiotic arrest. All phenotypes were restored to normal when the domesticus Prdm9dom2 allele was substituted with the Prdm9dom2H humanized variant. To conclude, our data show for the first time the male infertility of wild-derived musculus and domesticus subspecies F1 hybrids controlled by Prdm9 as the major hybrid sterility gene. The impairment of fertility surrogates, testes weight and sperm count, correlated with increasing difficulties of meiotic synapsis of homologous chromosomes and with meiotic arrest, which we suppose reflect the increasing asymmetry of PRDM9-dependent DNA double-strand breaks.
Alice Balard, Víctor Hugo Jarquín‐Díaz, Jenny Jost, Vivian Mittné, Francisca Böhning, Ľudovít Ďureje, Jaroslav Piálek, and Emanuel Heitlinger
Wiley
Abstract Resistance (host capacity to reduce parasite burden) and tolerance (host capacity to reduce impact on its health for a given parasite burden) manifest two different lines of defense. Tolerance can be independent from resistance, traded off against it, or the two can be positively correlated because of redundancy in underlying (immune) processes. We here tested whether this coupling between tolerance and resistance could differ upon infection with closely related parasite species. We tested this in experimental infections with two parasite species of the genus Eimeria. We measured proxies for resistance (the (inverse of) number of parasite transmission stages (oocysts) per gram of feces at the day of maximal shedding) and tolerance (the slope of maximum relative weight loss compared to day of infection on number of oocysts per gram of feces at the day of maximal shedding for each host strain) in four inbred mouse strains and four groups of F1 hybrids belonging to two mouse subspecies, Mus musculus domesticus and Mus musculus musculus. We found a negative correlation between resistance and tolerance against Eimeria falciformis, while the two are uncoupled against Eimeria ferrisi. We conclude that resistance and tolerance against the first parasite species might be traded off, but evolve more independently in different mouse genotypes against the latter. We argue that evolution of the host immune defenses can be studied largely irrespective of parasite isolates if resistance–tolerance coupling is absent or weak (E. ferrisi) but host–parasite coevolution is more likely observable and best studied in a system with negatively correlated tolerance and resistance (E. falciformis).
Barbora Vošlajerová Bímová, Miloš Macholán, Ľudovít Ďureje, Kateřina Berchová Bímová, Iva Martincová, and Jaroslav Piálek
Springer Science and Business Media LLC
The widespread and locally massive introgression of Y chromosomes of the eastern house mouse ( Mus musculus musculus ) into the range of the western subspecies ( M. m. domesticus ) in Central Europe calls for an explanation of its underlying mechanisms. Given the paternal inheritance pattern, obvious candidates for traits mediating the introgression are characters associated with sperm quantity and quality. We can also expect traits such as size, aggression or the length of generation cycles to facilitate the spread. We have created two consomic strains carrying the non-recombining region of the Y chromosome of the opposite subspecies, allowing us to study introgression in both directions, something impossible in nature due to the unidirectionality of introgression. We analyzed several traits potentially related to male fitness. Transmission of the domesticus Y onto the musculus background had negative effects on all studied traits. Likewise, domesticus males possessing the musculus Y had, on average, smaller body and testes and lower sperm count than the parental strain. However, the same consomic males tended to produce less- dissociated sperm heads, to win more dyadic encounters, and to have shorter generation cycles than pure domesticus males. These data suggest that the domesticus Y is disadvantageous on the musculus background, while introgression in the opposite direction can confer a recognizable, though not always significant, selective advantage. Our results are thus congruent with the unidirectional musculus → domesticus Y chromosome introgression in Central Europe. In addition to some previous studies, they show this to be a multifaceted phenomenon demanding a multidisciplinary approach.
Cristina Fevola, Chiara Rossi, Fausta Rosso, Matteo Girardi, Roberto Rosà, Mattia Manica, Luca Delucchi, Duccio Rocchini, Carol X. Garzon-Lopez, Daniele Arnoldi,et al.
Mary Ann Liebert Inc
Ljungan virus (LV), which belongs to the Parechovirus genus in the Picornaviridae family, was first isolated from bank voles (Myodes glareolus) in Sweden in 1998 and proposed as a zoonotic agent. To improve knowledge of the host association and geographical distribution of LV, tissues from 1685 animals belonging to multiple rodent and insectivore species from 12 European countries were screened for LV-RNA using reverse transcriptase (RT)-PCR. In addition, we investigated how the prevalence of LV-RNA in bank voles is associated with various intrinsic and extrinsic factors. We show that LV is widespread geographically, having been detected in at least one host species in nine European countries. Twelve out of 21 species screened were LV-RNA PCR positive, including, for the first time, the red vole (Myodes rutilus) and the root or tundra vole (Alexandromys formerly Microtus oeconomus), as well as in insectivores, including the bicolored white-toothed shrew (Crocidura leucodon) and the Valais shrew (Sorex antinorii). Results indicated that bank voles are the main rodent host for this virus (overall RT-PCR prevalence: 15.2%). Linear modeling of intrinsic and extrinsic factors that could impact LV prevalence showed a concave-down relationship between body mass and LV occurrence, so that subadults had the highest LV positivity, but LV in older animals was less prevalent. Also, LV prevalence was higher in autumn and lower in spring, and the amount of precipitation recorded during the 6 months preceding the trapping date was negatively correlated with the presence of the virus. Phylogenetic analysis on the 185 base pair species-specific sequence of the 5' untranslated region identified high genetic diversity (46.5%) between 80 haplotypes, although no geographical or host-specific patterns of diversity were detected.
Barbora Bendová, Jaroslav Piálek, Ľudovít Ďureje, Lucie Schmiedová, Dagmar Čížková, Jean-Francois Martin, and Jakub Kreisinger
Springer Science and Business Media LLC
Abstract Background The vertebrate gastrointestinal tract is colonised by microbiota that have a major effect on the host’s health, physiology and phenotype. Once introduced into captivity, however, the gut microbial composition of free-living individuals can change dramatically. At present, little is known about gut microbial changes associated with adaptation to a synanthropic lifestyle in commensal species, compared with their non-commensal counterparts. Here, we compare the taxonomic composition and diversity of bacterial and fungal communities across three gut sections in synanthropic house mouse (Mus musculus) and a closely related non-synanthropic mound-building mouse (Mus spicilegus). Results Using Illumina sequencing of bacterial 16S rRNA amplicons, we found higher bacterial diversity in M. spicilegus and detected 11 bacterial operational taxonomic units with significantly different proportions. Notably, abundance of Oscillospira, which is typically higher in lean or outdoor pasturing animals, was more abundant in non-commensal M. spicilegus. ITS2-based barcoding revealed low diversity and high uniformity of gut fungi in both species, with the genus Kazachstania clearly dominant. Conclusions Though differences in gut bacteria observed in the two species can be associated with their close association with humans, changes due to a move from commensalism to captivity would appear to have caused larger shifts in microbiota.
Alice Balard, Víctor Hugo Jarquín‐Díaz, Jenny Jost, Iva Martincová, Ľudovít Ďureje, Jaroslav Piálek, Miloš Macholán, Joëlle Goüy de Bellocq, Stuart J. E. Baird, and Emanuel Heitlinger
Wiley
Genetic diversity in animal immune systems is usually beneficial. In hybrid recombinants, this is less clear, as the immune system could also be impacted by genetic conflicts. In the European house mouse hybrid zone, the long‐standing impression that hybrid mice are more highly parasitized and less fit than parentals persists despite the findings of recent studies. Working across a novel transect, we assessed infections by intracellular protozoans, Eimeria spp., and infections by extracellular macroparasites, pinworms. For Eimeria, we found lower intensities in hybrid hosts than in parental mice but no evidence of lowered probability of infection or increased mortality in the centre of the hybrid zone. This means ecological factors are very unlikely to be responsible for the reduced load of infected hybrids. Focusing on parasite intensity (load in infected hosts), we also corroborated reduced pinworm loads reported for hybrid mice in previous studies. We conclude that intensity of diverse parasites, including the previously unstudied Eimeria, is reduced in hybrid mice compared to parental subspecies. We suggest caution in extrapolating this to differences in hybrid host fitness in the absence of, for example, evidence for a link between parasitemia and health.
Iva Martincová, Ľudovít Ďureje, Jakub Kreisinger, Miloš Macholán, and Jaroslav Piálek
Wiley
Abstract Hybrid zones between divergent populations sieve genomes into blocks that introgress across the zone, and blocks that do not, depending on selection between interacting genes. Consistent with Haldane's rule, the Y chromosome has been considered counterselected and hence not to introgress across the European house mouse hybrid zone. However, recent studies detected massive invasion of M. m. musculus Y chromosomes into M. m. domesticus territory. To understand mechanisms facilitating Y spread, we created 31 recombinant lines from eight wild‐derived strains representing four localities within the two mouse subspecies. These lines were reciprocally crossed and resulting F1 hybrid males scored for five phenotypic traits associated with male fitness. Molecular analyses of 51 Y‐linked SNPs attributed ~50% of genetic variation to differences between the subspecies and 8% to differentiation within both taxa. A striking proportion, 21% (frequencies of sperm head abnormalities) and 42% (frequencies of sperm tail dissociations), of phenotypic variation was explained by geographic Y chromosome variants. Our crossing design allowed this explanatory power to be examined across a hierarchical scale from subspecific to local intrastrain effects. We found that divergence and variation were expressed diversely in different phenotypic traits and varied across the whole hierarchical scale. This finding adds another dimension of complexity to studies of Y introgression not only across the house mouse hybrid zone but potentially also in other contact zones.
Linn E. Knutsen, Erik Dissen, Per C. Saether, Elisabeth Gyllensten Bjørnsen, Jaroslav Piálek, Anne K. Storset, and Preben Boysen
Springer Science and Business Media LLC
The CD94 receptor, expressed on natural killer (NK) and CD8+ T cells, is known as a relatively non-polymorphic receptor with orthologues in humans, other primates, cattle, and rodents. In the house mouse (Mus musculus), a single allele is highly conserved among laboratory strains, and reports of allelic variation in lab- or wild-living mice are lacking, except for deficiency in one lab strain (DBA/2J). The non-classical MHC-I molecule Qa-1b is the ligand for mouse CD94/NKG2A, presenting alternative non-americ fragment of leader peptides (Qa-1 determinant modifier (Qdm)) from classical MHC-I molecules. Here, we report a novel allele identified in free-living house mice captured in Norway, living among individuals carrying the canonical Cd94 allele. The novel Cd94LocA allele encodes 12 amino acid substitutions in the extracellular lectin-like domain. Flow cytometric analysis of primary NK cells and transfected cells indicates that the substitutions prevent binding of CD94 mAb and Qa-1b/Qdm tetramers. Our data further indicate correlation of Cd94 polymorphism with the two major subspecies of house mice in Europe. Together, these findings suggest that the Cd94LocA/NKG2A heterodimeric receptor is widely expressed among M. musculus subspecies musculus, with ligand-binding properties different from mice of subspecies domesticus, such as the C57BL/6 strain.
Joëlle Goüy de Bellocq, Wasimuddin, Alexis Ribas, Josef Bryja, Jaroslav Piálek, and Stuart J. E. Baird
Wiley
Parasite hybrid zones resulting from host secondary contact have never been described in nature although parasite hybridization is well known and secondary contact should affect them similarly to free‐living organisms. When host populations are isolated, diverge and recontact, intimate parasites (host specific, direct life cycle) carried during isolation will also meet and so may form parasite hybrid zones. If so, we hypothesize these should be narrower than the host’s hybrid zone as shorter parasite generation time allows potentially higher divergence. We investigate multilocus genetics of two parasites across the European house mouse hybrid zone. We find each host taxon harbours its own parasite taxa. These also hybridize: Parasite hybrid zones are significantly narrower than the host’s. Here, we show a host hybrid zone is a suture zone for a subset of its parasite community and highlight the potential of such systems as windows on the evolutionary processes of host–parasite interactions and recombinant pathogen emergence.
Joerg P. Burgstaller, Thomas Kolbe, Vitezslav Havlicek, Stephanie Hembach, Joanna Poulton, Jaroslav Piálek, Ralf Steinborn, Thomas Rülicke, Gottfried Brem, Nick S. Jones,et al.
Springer Science and Business Media LLC
Vital mitochondrial DNA (mtDNA) populations exist in cells and may consist of heteroplasmic mixtures of mtDNA types. The evolution of these heteroplasmic populations through development, ageing, and generations is central to genetic diseases, but is poorly understood in mammals. Here we dissect these population dynamics using a dataset of unprecedented size and temporal span, comprising 1947 single-cell oocyte and 899 somatic measurements of heteroplasmy change throughout lifetimes and generations in two genetically distinct mouse models. We provide a novel and detailed quantitative characterisation of the linear increase in heteroplasmy variance throughout mammalian life courses in oocytes and pups. We find that differences in mean heteroplasmy are induced between generations, and the heteroplasmy of germline and somatic precursors diverge early in development, with a haplotype-specific direction of segregation. We develop stochastic theory predicting the implications of these dynamics for ageing and disease manifestation and discuss its application to human mtDNA dynamics.Mitochondrial populations in cells may consist of heteroplasmic mixtures of mtDNA types, and their evolution through development, aging and generations is central to genetic diseases. Here the authors dissect these population dynamics using a large mouse-based data set to characterise the dynamics of heteroplasmy mean and variance throughout life and across generations.
Dagmar Čížková, Stuart J.E. Baird, Jana Těšíková, Sebastian Voigt, Ďureje Ľudovít, Jaroslav Piálek, and Joëlle Goüy de Bellocq
Elsevier BV
Barbora Bílková, Tomáš Albrecht, Milada Chudíčková, Vladimír Holáň, Jaroslav Piálek, and Michal Vinkler
Wiley
Abstract The skin‐swelling test is a simple and widespread method used in field ecological research to estimate cellular immune responsiveness in animals. This immunoecological test is based on measuring the magnitude of tissue swelling response at specific times following subcutaneous application of an experimental pro‐inflammatory stimulant. In the vast majority of studies across vertebrate taxa, phytohemagglutinin (PHA) is used as a universal stimulant. Given the complexity of immune response activation pathways of PHA, however, interpretation of test results can be ambiguous. Goal of this study was to improve methodology of the skin‐swelling test to decrease this ambiguity. Here, we present an alternative protocol aimed at facilitating interpretation of skin‐swelling data for mammals. Based on previous evidence suggesting that mammalian T cells are readily activated by Concanavalin A (ConA) in vitro, we compared cellular immune responses in vivo to PHA and ConA as an alternative pro‐inflammatory stimulant in mice. We measured magnitude of tissue swelling and compared it with intensity of blood cell infiltration into tissue over a 72‐hour interval. Our results corroborate that PHA and ConA show important differences in both dynamics and response amplitude in rodents. ConA induces stronger swelling with a distinct leukocyte activity pattern and higher pro‐inflammatory cytokine (interleukin 6 [IL‐6] and interferon gamma[IFN‐γ]) expression than PHA during peak response (24‐h post‐treatment). Furthermore, unlike PHA, magnitude of swelling was positively associated with cellular activity (number of neutrophils infiltrating tissue) following ConA injection. We conclude that ConA is the more suitable stimulant for skin‐swelling tests in mammals. This is because of the molecular binding specificity in the two lectins, that is, ConA specifically activates T cells while PHA also triggers erythroagglutination. We propose that ConA be used in all future ecological testing in mammals as it exhibits better performance and its application facilitates immunological interpretation of skin‐swelling test results.
Wasimuddin, Josef Bryja, Alexis Ribas, Stuart J. E. Baird, Jaroslav Piálek, and Joëlle Goüy de Bellocq
Wiley
Abstract Host‐parasite interaction studies across hybrid zones often focus on host genetic variation, treating parasites as homogeneous. ‘Intimately’ associated hosts and parasites might be expected to show similar patterns of genetic structure. In the literature, factors such as no intermediate host and no free‐living stage have been proposed as ‘intimacy’ factors likely constraining parasites to closely follow the evolutionary history of their hosts. To test whether the whipworm, Trichuris muris, is intimately associated with its house mouse host, we studied its population genetics across the European house mouse hybrid zone (HMHZ) which has a strong central barrier to gene flow between mouse taxa. T. muris has a direct life cycle and nonmobile free stage: if these traits constrain the parasite to an intimate association with its host we expect a geographic break in the parasite genetic structure across the HMHZ. We genotyped 205 worms from 56 localities across the HMHZ and additionally T. muris collected from sympatric woodmice (Apodemus spp.) and allopatric murine species, using mt‐COX1, ITS1‐5.8S‐ITS2 rDNA and 10 microsatellites. We show four haplogroups of mt‐COX1 and three clear ITS1‐5.8S‐ITS2 clades in the HMHZ suggesting a complex demographic/phylogeographic history. Microsatellites show strong structure between groups of localities. However, no marker type shows a break across the HMHZ. Whipworms from Apodemus in the HMHZ cluster, and share mitochondrial haplotypes, with those from house mice. We conclude Trichuris should not be regarded as an ‘intimate’ parasite of the house mouse: while its life history might suggest intimacy, passage through alternate hosts is sufficiently common to erase signal of genetic structure associated with any particular host taxon.
There are errors in the Funding section. The correct funding information is as follows: Research was supported by the Czech Science Foundation (206–08–0640), the Ministry of Education, Youth and Sport of the Czech Republic (SVV260 087/2014), and the National Science Foundation (DEB0746560). Mouse pellets and genotyping of allopatric mice were reimbursed from the Czech Science Foundation (P506–11–1792). The funders had no role in study design, data collection, data analysis, decision to publish, or preparation of the manuscript.
L. Kropáčková, J. Piálek, V. Gergelits, J. Forejt, and R. Reifová
Wiley
Interspecific hybridization between closely related mammalian species, including various species of the genus Mus, is commonly associated with abnormal growth of the placenta and hybrid foetuses, a phenomenon known as hybrid placental dysplasia (HPD). The role of HPD in speciation is anticipated but still poorly understood. Here, we studied placental and foetal growth in F1 crosses between four inbred mouse strains derived from two house mouse subspecies, Mus musculus musculus and Mus musculus domesticus. These subspecies are in the early stage of speciation and still hybridize in nature. In accordance with the maternal–foetal genomic conflict hypothesis, we found different parental influences on placental and foetal development, with placental weight most affected by the father's body weight and foetal weight by the mother's body weight. After removing the effects of parents’ body weight, we did not find any significant differences in foetal or placental weights between intra‐subspecific and inter‐subspecific F1 crosses. Nevertheless, we found that the variability in placental weight in inter‐subspecific crosses is linked to the X chromosome, similarly as for HPD in interspecific mouse crosses. Our results suggest that maternal–foetal genomic conflict occurs in the house mouse system, but has not yet diverged sufficiently to cause abnormalities in placental and foetal growth in inter‐subspecific crosses. HPD is thus unlikely to contribute to speciation in the house mouse system. However, we cannot rule out that it might have contributed to other speciation events in the genus Mus, where differences in the levels of polyandry exist between the species.
Joëlle Goüy de Bellocq, Stuart J. E. Baird, Jana Albrechtová, Karolína Sobeková, and Jaroslav Piálek
American Society for Microbiology
ABSTRACT Murine cytomegalovirus (MCMV) is a betaherpesvirus of the house mouse, Mus musculus domesticus . It is a common infectious agent of wild mice and a highly studied pathogen of the laboratory mouse. Betaherpesviruses are specific to their hosts, and it is not known if other Mus taxa carry MCMV or if it is restricted to M. m. domesticus . We sampled mice over a 145-km transect of Bavaria-Bohemia crossing a hybrid zone between M. m. domesticus and Mus musculus musculus in order to investigate the occurrence of MCMV in two Mus subspecies and to test the limits of the specificity of the virus for its host. We hypothesized that if the two subspecies carry MCMV and if the virus is highly specific to its host, divergent MCMV lineages would have codiverged with their hosts and would have a geographical distribution constrained by the host genetic background. A total of 520 mice were tested by enzyme-linked immunosorbent assay (ELISA) and/or nested PCR targeting the M94 gene. Seropositive and PCR-positive individuals were found in both Mus subspecies. Seroprevalence was high, at 79.4%, but viral DNA was detected in only 41.7% of mice. Sequencing revealed 20 haplotypes clustering in 3 clades that match the host genetic structure in the hybrid zone, showing 1 and 2 MCMV lineages in M. m. domesticus and M. m. musculus , respectively. The estimated time to the most recent common ancestor (1.1 million years ago [Mya]) of the MCMVs matches that of their hosts. In conclusion, MCMV has coevolved with these hosts, suggesting that its diversity in nature may be underappreciated, since other members of the subgenus Mus likely carry different MCMVs. IMPORTANCE Murine cytomegalovirus (MCMV) is a betaherpesvirus of the house mouse, Mus musculus domesticus , an important lab model for human cytomegalovirus (HCMV) infection. The majority of lab studies are based on only two strains of MCMVs isolated from M. m. domesticus , Smith and K181, the latter derived from repeated passage of Smith in mouse submaxillary glands. The presence of MCMV in other members of the Mus subgenus had not even been investigated. By screening mouse samples collected in the European house mouse hybrid zone between M. m. domesticus and M. m. musculus , we show that MCMV is not restricted to the M. m. domesticus subspecies and that MCMVs likely codiverged with their Mus hosts. Thus, the diversity of MCMV in nature may be seriously underappreciated, since other members of the subgenus Mus likely carry their own MCMV lineages.
Jana Albrechtová, Tomáš Albrecht, Ludovít Ďureje, Vincent A. Pallazola, and Jaroslav Piálek
Public Library of Science (PLoS)
Being subject to intense post-copulatory selection, sperm size is a principal determining component of male fitness. Although previous studies have presented comparative sperm size data at higher taxonomic levels, information on the evolution of sperm size within species is generally lacking. Here, we studied two house mouse subspecies, Mus musculus musculus and Mus musculus domesticus, which undergo incipient speciation. We measured four sperm dimensions from cauda epididymis smears of 28 wild-caught mice of both subspecies. As inbred mouse strains are frequently used as proxies for exploring evolutionary processes, we further studied four wild-derived inbred strains from each subspecies. The subspecies differed significantly in terms of sperm head length and midpiece length, and these differences were consistent for wild mice and wild-derived strains pooled over genomes. When the inbred strains were analyzed individually, however, their strain-specific values were in some cases significantly shifted from subspecies-specific values derived from wild mice. We conclude that: (1) the size of sperm components differ in the two house mouse subspecies studied, and that (2) wild-derived strains reflect this natural polymorphism, serving as a potential tool to identify the genetic variation driving these evolutionary processes. Nevertheless, we suggest that more strains should be used in future experiments to account for natural variation and to avoid confounding results due to reduced variability and/or founder effect in the individual strains.
Jakub Kreisinger, Dagmar Čížková, Jaroslav Vohánka, and Jaroslav Piálek
Wiley
The effects of gastrointestinal tract microbiota (GTM) on host physiology and health have been the subject of considerable interest in recent years. While a variety of captive bred species have been used in experiments, the extent to which GTM of captive and/or inbred individuals resembles natural composition and variation in wild populations is poorly understood. Using 454 pyrosequencing, we performed 16S rDNA GTM barcoding for 30 wild house mice (Mus musculus) and wild‐derived inbred strain mice belonging to two subspecies (M. m. musculus and M. m. domesticus). Sequenced individuals were selected according to a 2 × 2 experimental design: wild (14) vs. inbred origin (16) and M. m. musculus (15) vs. M. m. domesticus (15). We compared alpha diversity (i.e. number of operational taxonomic units – OTUs), beta diversity (i.e. interindividual variability) and microbiota composition across the four groups. We found no difference between M. m. musculus and M. m. domesticus subspecies, suggesting low effect of genetic differentiation between these two subspecies on GTM structure. Both inbred and wild populations showed the same level of microbial alpha and beta diversity; however, we found strong differentiation in microbiota composition between wild and inbred populations. Relative abundance of ~ 16% of OTUs differed significantly between wild and inbred individuals. As laboratory mice represent the most abundant model for studying the effects of gut microbiota on host metabolism, immunity and neurology, we suggest that the distinctness of laboratory‐kept mouse microbiota, which differs from wild mouse microbiota, needs to be considered in future biomedical research.