Sexual selection and the rodent baculum: an intraspecific study in the house mouse (<Emphasis Type="Italic">Mus musculus domesticus</Emphasis>)

The rapid divergence of genitalia is a pervasive trend in animal evolution, thought to be due to the action of sexual selection. To test predictions from the sexual selection hypothesis, we here report data on the allometry, variation, plasticity and condition dependence of baculum morphology in the house mouse (Mus musculus domesticus). We find that that baculum size: (a) exhibits no consistent pattern of allometric scaling (baculum size being in most cases unrelated to body size), (b) exhibits low to moderate levels of phenotypic variation, (c) does not exhibit phenotypic plasticity in response to differences in perceived levels of sexual competition and (d) exhibits limited evidence of condition dependence. These patterns provide only limited evidence in support of the sexual selection hypothesis, and no consistent support for any particular sexual selection mechanism; however, more direct measures of how genital morphology influences male fertilization success are required.     

The location of the<Emphasis Type="Italic">Mus musculus/M. domesticus</Emphasis> hybrid zone in the Balkans: clues from morphology

Three morphological characters were used to depict the position of the hybrid zone between two species of house mice,M. musculus Linnaeus, 1758 andM. domesticus Schwarz et Schwarz, 1943, across a vast area covering countries of the former Yugoslavia, Albania, Bulgaria and Greece. Quantitative approach based on a morphological index (MI), resembling the hybrid index widely used in allozyme-based genetic studies, was used. The zone crosses Slovenia south of the Sava River, and then follows the Dinaric Mts to Montenegro and northern Albania. Contrary to many previously published results, the zone was found to run parallel with northern borders of Albania and the former Yugoslavian Macedonia, about 150 km north of the Greek border, thus giving its course rather “shallow” appearance at this part of the Balkan Peninsula.     

Preimplantation embryo development (<Emphasis Type="Italic">Ped</Emphasis>) gene copy number varies from 0 to 85 in a population of wild mice identified as <Emphasis Type="Italic">Mus musculus domesticus</Emphasis>

The preimplantation embryo development (Ped) gene regulates the rate of preimplantation embryonic cleavage division and subsequent embryo survival. In the mouse, the Ped gene product is Qa-2 protein, a nonclassical MHC class I molecule encoded by four tandem genes, Q6/Q7/Q8/Q9. Most inbred strains of mice have all four genes on each allelic chromosome, making a total of eight Qa-2 encoding genes, but there are a few strains that are missing all eight genes, defining a null allele. Mouse strains with the presence of the Qa-2 encoding genes express Qa-2 protein and produce embryos with a faster rate of preimplantation embryonic development and a greater chance of embryo survival compared to mouse strains with the null allele. There is extensive evidence that the human homolog of Qa-2 is HLA-G. HLA-G in humans, like Qa-2 in mice, is associated with enhanced reproductive success. The human population is an outbred population. Therefore, for a better comparison to the human population, we undertook an investigation of the presence of the genes encoding Qa-2 in an outbred population of mice. We used Real-Time Quantitative PCR to quantify the number of Qa-2 encoding genes in a population of 32 wild mice identified as Mus musculus domesticus both by morphologic assessment and by PCR analysis of their DNA. We found great variability in the number of Qa-2 encoding genes in the wild mice tested. The wild mouse with the highest number of Qa-2 encoding genes had 85 such genes, whereas we discovered one wild mouse without any Qa-2 encoding genes. Evolutionary implications of a range of Qa-2 encoding gene numbers in the wild mouse population are discussed, as well as the relevance of our findings to humans.     

L-glucose absorption in house sparrows (<Emphasis Type="Italic">Passer domesticus</Emphasis>) is nonmediated

We previously demonstrated in intact house sparrows substantial absorption in vivo of L-glucose, the stereoisomer of D-glucose that is assumed not to interact with the intestines D-glucose transporter. Results of some studies challenge this assumption for other species. Therefore, we tested it in vitro and in vivo, based on the principle that if absorption of a compound (L-glucose) is mediated, then absorption of its tracer will be competitively inhibited by high concentrations of either the compound itself or other compounds (e.g., D-glucose) whose absorption is mediated by the same mechanism. An alternative hypothesis that L-glucose absorption is primarily paracellular predicts that its absorption in vivo will be increased (not decreased) in the presence of D-glucose, because the permeability of this pathway is supposedly enhanced when Na⁺-coupled glucose absorption occurs. First, using intact tissue in vitro, we found that uptake of tracer-radiolabeled L-glucose was not significantly inhibited by high concentrations (100 mM) of either L-glucose or 3-O-methyl-D-glucose, a non-metabolizable but actively transported D-glucose analogue. Second, using intact house sparrows, we found that fractional absorption of the L-glucose tracer was significantly increased, not reduced, when gavaged along with 200 mM 3-O-methyl-D-glucose. This result was confirmed in another experiment where L-glucose fractional absorption was significantly higher in the presence vs. absence of food in the gut. The greater absorption was apparently not due simply to longer retention time of digesta, because no significant difference was found among retention times. Our results are consistent with the idea that L-glucose is absorbed in a non-mediated fashion, largely via the paracellular pathway in vivo.Abbreviations AUC area under the curve - 3OMD-glucose 3-O-methyl-D-glucose Communicated by I.D. Hume     

<Emphasis Type="Italic">Ty</Emphasis>1<Emphasis Type="Italic">/copia</Emphasis>- and <Emphasis Type="Italic">Ty</Emphasis>3<Emphasis Type="Italic">/gypsy</Emphasis>-like DNA sequences in <Emphasis Type="Italic">Helianthus </Emphasis>species

Two repeated DNA sequences isolated from a partial genomic DNA library of Helianthus annuus, p HaS13 and p HaS211, were shown to represent portions of the int gene of a Ty3 /gypsy retroelement and of the RNase-Hgene of a Ty1 /copia retroelement, respectively. Southern blotting patterns obtained by hybridizing the two probes to BglII- or DraI-digested genomic DNA from different Helianthus species showed p HaS13 and p HaS211 were parts of dispersed repeats at least 8 and 7 kb in length, respectively, that were conserved in all species studied. Comparable hybridization patterns were obtained in all species with p HaS13. By contrast, the patterns obtained by hybridizing p HaS211 clearly differentiated annual species from perennials. The frequencies of p HaS13- and p HaS211-related sequences in different species were 4.3x10(4)-1.3x10(5) copies and 9.9x10(2)-8.1x10(3) copies per picogram of DNA, respectively. The frequency of p HaS13-related sequences varied widely within annual species, while no significant difference was observed among perennial species. Conversely, the frequency variation of p HaS211-related sequences was as large within annual species as within perennials. Sequences of both families were found to be dispersed along the length of all chromosomes in all species studied. However, Ty3 /gypsy-like sequences were localized preferentially at the centromeric regions, whereas Ty1/ copia-like sequences were less represented or absent around the centromeres and plentiful at the chromosome ends. These findings suggest that the two sequence families played a role in Helianthusgenome evolution and species divergence, evolved independently in the same genomic backgrounds and in annual or perennial species, and acquired different possible functions in the host genomes.     

Revision of the <Emphasis Type="Italic">Serrulati</Emphasis> species of <Emphasis Type="Italic">Penstemon</Emphasis> section <Emphasis Type="Italic">Saccanthera</Emphasis> subsection <Emphasis Type="Italic">Serrulati</Emphasis>

A revision of Penstemon sect. Saccanthera subsect. Serrulati includes a new species (P. salmonensis), a new variety (P. triphyllus var. infernalis), and the elevation of a subspecies to species (P. curtiflorus), bringing the total number of species to eight, which are keyed and described, complete with nomenclature and type citations.     

Peroxidase activity of cytochrome <Emphasis Type="Italic">bd</Emphasis> from <Emphasis Type="Italic">Escherichia coli</Emphasis>

Cytochrome bd from Escherichia coli is able to oxidize such substrates as guaiacol, ferrocene, benzohydroquinone, and potassium ferrocyanide through the peroxidase mechanism, while none of these donors is oxidized in the oxidase reaction (i.e. in the reaction that involves molecular oxygen as the electron acceptor). Peroxidation of guaiacol has been studied in detail. The dependence of the rate of the reaction on the concentration of the enzyme and substrates as well as the effect of various inhibitors of the oxidase reaction on the peroxidase activity have been tested. The dependence of the guaiacol-peroxidase activity on the H₂O₂ concentration is linear up to the concentration of 8 mM. At higher concentrations of H₂O₂, inactivation of the enzyme is observed. Guaiacol markedly protects the enzyme from inactivation induced by peroxide. The peroxidase activity of cytochrome bd increases with increasing guaiacol concentration, reaching saturation in the range from 0.5 to 2.5 mM, but then starts falling. Such inhibitors of the ubiquinol-oxidase activity of cytochrome bd as cyanide, pentachlorophenol, and 2-n-heptyl 4-hydroxyquinoline-N-oxide also suppress its guaiacol-peroxidase activity; in contrast, zinc ions have no influence on the enzyme-catalyzed peroxidation of guaiacol. These data suggest that guaiacol interacts with the enzyme in the center of ubiquinol binding and donates electrons into the di-heme center of oxygen reduction via heme b ₅₅₈, and H₂O₂ is reduced by heme d. Although the peroxidase activity of cytochrome bd from E. coli is low compared to peroxidases, it might be of physiological significance for the bacterium itself and plays a pathophysiological role for humans and animals.     

<Emphasis Type="Italic">Agrobacterium</Emphasis><Emphasis Type="Italic">tumefaciens</Emphasis>-mediated transformation of callus cells of <Emphasis Type="Italic">Crataegus</Emphasis><Emphasis Type="Italic">aronia</Emphasis>

A genetic transformation system has been developed for callus cells of Crataegus aronia using Agrobacterium tumefaciens. Callus culture was established from internodal stem segments incubated on Murashige and Skoog (MS) medium supplemented with 5 mg l⁻¹ Indole-3-butyric acid (IBA) and 0.5 mg l⁻¹ 6-benzyladenine (BA). In order to optimize the callus culture system with respect to callus growth and coloration, different types and concentrations of plant growth regulators were tested. Results indicated that the best average fresh weight of red colored callus was obtained on MS medium supplemented with 2 mg l⁻¹ 2,4-dichlorophenoxyacetic acid (2,4-D) and 1.5 mg l⁻¹ kinetin (Kin) (callus maintenance medium). Callus cells were co-cultivated with Agrobacterium harboring the binary plasmid pCAMBIA1302 carrying the mgfp5 and hygromycin phosphotransferase (hptII) genes conferring green fluorescent protein (GFP) activity and hygromycin resistance, respectively. Putative transgenic calli were obtained 4 weeks after incubation of the co-cultivated explants onto maintenance medium supplemented with 50 mg l⁻¹ hygromycin. Molecular analysis confirmed the integration of the transgenes in transformed callus. To our knowledge, this is the first time to report an Agrobacterium-mediated transformation system in Crataegus aronia.     

<Emphasis Type="Italic">Galleria</Emphasis><Emphasis Type="Italic">mellonella</Emphasis> are Resistant to <Emphasis Type="Italic">Pneumocystis</Emphasis><Emphasis Type="Italic">murina</Emphasis> Infection

Studying Pneumocystis has proven to be a challenge from the perspective of propagating a significant amount of the pathogen in a facile manner. The study of several fungal pathogens has been aided by the use of invertebrate model hosts. Our efforts to infect the invertebrate larvae Galleria mellonella with Pneumocystis proved futile since P. murina neither caused disease nor was able to proliferate within G. mellonella. It did, however, show that the pathogen could be rapidly cleared from the host.     

Allozyme polymorphism in <Emphasis Type="Italic">Drosophila</Emphasis>

Every population possesses genetic variations which are achieved through gene mutation, genetic recombination, hybridization, gene duplication etc. These genetic variations provide raw materials for evolutionary forces to create a better surviving species. Genetic polymorphism is reflected at every level in the populations, for example, at phenotypic, chromosomal, protein and DNA levels. Protein or enzyme polymorphisms have been well studied in various organisms including Drosophila and humans. Drosophila has proven to be a good model organism for carrying out polymorphism studies. Among the different species of Drosophila, there is a wide variation in the levels of allozyme polymorphisms and heterozygosities which depends upon species, geographical regions, number and nature of loci in question etc. In Drosophila, the average polymorphic enzyme loci and average heterozygosity ranges from 35 to 70 percent and 10 to 20 percent respectively. The genetic differentiation as observed through allozyme or isozyme variation affords an important parameter in evaluating the phylogenetic relationships between different species of Drosophila and also for discussing the adaptive significance of allozyme polymorphisms. Therefore, this review attempts to compile all studies on allozyme polymorphism in Drosophila that have been undertaken so far.     

Diversity and recombination in <Emphasis Type="Italic">Wolbachia</Emphasis> and <Emphasis Type="Italic">Cardinium</Emphasis> from <Emphasis Type="Italic">Bryobia</Emphasis>spider mites

BACKGROUND: Wolbachia and Cardinium are endosymbiotic bacteria infecting many arthropods and manipulating host reproduction. Although these bacteria are maternally transmitted, incongruencies between phylogenies of host and parasite suggest an additional role for occasional horizontal transmission. Consistent with this view is the strong evidence for recombination in Wolbachia, although it is less clear to what extent recombination drives diversification within single host species and genera. Furthermore, little is known concerning the population structures of other insect endosymbionts which co-infect with Wolbachia, such as Cardinium. Here, we explore Wolbachia and Cardinium strain diversity within nine spider mite species (Tetranychidae) from 38 populations, and quantify the contribution of recombination compared to point mutation in generating Wolbachia diversity. RESULTS: We found a high level of genetic diversity for Wolbachia, with 36 unique strains detected (64 investigated mite individuals). Sequence data from four Wolbachia genes suggest that new alleles are 7.5 to 11 times more likely to be generated by recombination than point mutation. Consistent with previous reports on more diverse host samples, our data did not reveal evidence for co-evolution of Wolbachia with its host. Cardinium was less frequently found in the mites, but also showed a high level of diversity, with eight unique strains detected in 15 individuals on the basis of only two genes. A lack of congruence among host and Cardinium phylogenies was observed. CONCLUSIONS: We found a high rate of recombination for Wolbachia strains obtained from host species of the spider mite family Tetranychidae, comparable to rates found for horizontally transmitted bacteria. This suggests frequent horizontal transmission of Wolbachia and/or frequent horizontal transfer of single genes. Our findings strengthens earlier reports of recombination for Wolbachia, and shows that high recombination rates are also present on strains from a restrictive host range. Cardinium was found co-infecting several spider mite species, and phylogenetic comparisons suggest also horizontal transmission of Cardinium among hosts.     

<Emphasis Type="Italic">Diplazium</Emphasis> hybrids involving <Emphasis Type="Italic">D. plantaginifolium</Emphasis> and <Emphasis Type="Italic">D</Emphasis>. <Emphasis Type="Italic">ternatum</Emphasis> from Mexico and Central America

Here we evaluate the origins and relationships of Mexican and Central American Diplazium hybrids derived from crosses involving either D. plantaginifolium or D. ternatum. Based on study of live plants and herbarium specimens, we distinguish D. ×verapax from the similar D. riedelianum and present evidence that the former is a sterile hybrid derived from a cross between D. plantaginifolium and D. werckleanum. We also describe new hybrids, D. ×torresianum and D. ×subternatum from Mexico and northern Central America. Both involve D. ternatum as one parent. Diplazium. cristatum is the other putative parent of D. ×torresianum, and D. plantaginifolium is the second parent of D. ×subternatum. We also designate lectotypes for D. cordovense and D. dissimile.     

Regulatory activity of heterologous gene-activator <Emphasis Type="Italic">xlnR</Emphasis> of <Emphasis Type="Italic">Aspergillus niger</Emphasis> in <Emphasis Type="Italic">Penicillium canescens</Emphasis>

The gene encoding the xlnR xylanolytic activator of the heterologous fungus Aspergillus niger was incorporated into the Penicillium canescens genome. Integration of the xlnR gene resulted in the increase in a number of activities, i.e. endoxylanase, β-xylosidase, α-L-arabinofuranosidase, α-galactosidase, and feruloyl esterase, compared to the host P. canescens PCA 10 strain, while β-galactosidase, β-glucosidase, endoglucanase, and CMCase activities remained constant. Two different expression constructs were developed. The first consisted of the nucleotide sequence containing the mature P. canescens phytase gene under control of the axhA promoter region gene encoding A. niger (1,4)-β-D-arabinoxylan-arabinofuranohydrolase. The second construct combined the P. canescens phytase gene and the bgaS promoter region encoding homologous β-galactosidase. Both expression cassettes were transformed into P. canescens host strain containing xlnR. Phytase synthesis was observed only for strains with the bgaS promoter on arabinose-containing culture media. In conclusion, the bgaS and axhA promoters were regulated by different inducers and activators in the P. canescens strain containing a structural tandem of the axhA promoter and the gene of the xlnR xylanolytic activator.     

Antifungal activity of xenocoumacin 1 from <Emphasis Type="Italic">Xenorhabdus nematophilus</Emphasis> var. <Emphasis Type="Italic">pekingensis</Emphasis> against <Emphasis Type="Italic">Phytophthora infestans</Emphasis>

Potato late blight disease, which is caused by the fungus Phytophthora infestans, results in considerable loss of potato crop yield worldwide. Developing new bio-agents to control this disease is desirable. Xenocoumacin 1 (Xcn1) is an antibacterial substance from the entomopathogenic nematode symbiotic bacterium, Xenorhabdus nematophila var. pekingensis. In this study, we evaluated the antifungal activity of Xcn1, along with its potential activity against Phytophthora infestans, in vitro and in vivo. The results showed that Xcn1 exhibits strong antifungal activity against five species of Phytophthora, with EC₅₀ values ranging from 0.25 to 4.17 μg/mL. Xcn1 not only inhibited mycelial growth of P. infestans, reaching 100% inhibition at 1.5 μg/mL of Xcn1, but also suppressed sporangia production. Xcn1 also showed potent in vivo activity against P. infestans, with 92.63% and 80.27% in detached plants and potted plants, respectively, in comparison with the control. Therefore, Xcn1 has antibiotic activities against P. infestans both in vitro and in vivo.     

An <Emphasis Type="Italic">en masse</Emphasis> phenotype and function prediction system for <Emphasis Type="Italic">Mus musculus</Emphasis>

Background:

Individual researchers are struggling to keep up with the accelerating emergence of high-throughput biological data, and to extract information that relates to their specific questions. Integration of accumulated evidence should permit researchers to form fewer - and more accurate - hypotheses for further study through experimentation.

Results:

Here a method previously used to predict Gene Ontology (GO) terms for Saccharomyces cerevisiae (Tian et al.: Combining guilt-by-association and guilt-by-profiling to predict Saccharomyces cerevisiae gene function. Genome Biol 2008, 9(Suppl 1):S7) is applied to predict GO terms and phenotypes for 21,603 Mus musculus genes, using a diverse collection of integrated data sources (including expression, interaction, and sequence-based data). This combined 'guilt-by-profiling' and 'guilt-by-association' approach optimizes the combination of two inference methodologies. Predictions at all levels of confidence are evaluated by examining genes not used in training, and top predictions are examined manually using available literature and knowledge base resources.

Conclusion:

We assigned a confidence score to each gene/term combination. The results provided high prediction performance, with nearly every GO term achieving greater than 40% precision at 1% recall. Among the 36 novel predictions for GO terms and 40 for phenotypes that were studied manually, >80% and >40%, respectively, were identified as accurate. We also illustrate that a combination of 'guilt-by-profiling' and 'guilt-by-association' outperforms either approach alone in their application to M. musculus.