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PubMed2006

Performance and behaviour of rabbit does in a group-housing system with natural mating or artificial insemination.

This study compared reproductive performance and behaviour of does raised in a group-housing system and in a regular cage system. The group-housing pen was divided into different functional areas for suckling, resting, and eating and special hiding areas for kits when they had left the nest-boxes and does to favour the species specific behavioural traits. Does had access to their nest-box by means of an individual Electronic Nest-box Recognition System (ENRS) activated by a coded transponder placed in their eartags. Eight does were housed in each pen. Natural mating (NM, with a buck in the group) or artificial inseminations (AI) were applied. Litter size, kit mortality and kit weight at 14 d of age were similar for group-housing and cages when NM were applied. With a natural reproduction rhythm group-housing led to an increase of +38% of litters. However, from a management point of view, a cycled production system with AI is preferred. With AI and group-housing, a lower kindling rate and a lower kit weight at weaning were found. The lower kindling rate was partly caused by pseudo-pregnancies that were found in 23% (P < 0.01) of the does in the group-housing system against 0% in the control group. Sixteen to 20% of the does in the group-housing system had skin injuries, which is an indicator for aggression among does. Most of the injuries were seen on the body and most of them were superficial bites. Based on the results of this study, it can be concluded that group-housing of rabbit does seems possible, but more research is needed to solve the problems of the decreased kindling rate and occurrence of pseudo-pregnancies, the lower weight at weaning and aggressiveness among does.

Aggression↗
PubMed1993

The mating pair formation system of plasmid RP4 defined by RSF1010 mobilization and donor-specific phage propagation.

Transfer functions of the conjugative plasmid RP4 (IncP alpha) are distributed among distinct regions of the genome, designated Tra1 and Tra2. By deletion analyses, we determined the limits of the Tra1 region, essential for intraspecific Escherichia coli matings. The Tra1 core region encompasses approximately 5.8 kb, including the genes traF, -G, -H, -I, -J, and -K as well as the origin of transfer. The traM gene product, however, is not absolutely required for conjugation but significantly increases transfer efficiency. To determine the transfer phenotype of genes encoded by the Tra2 core region, we generated a series of defined Tra2 mutants. This revealed that at least trbB, -C, -E, -G, and -L are essential for RP4 conjugation. To classify these transfer functions as components of the DNA transfer and replication (Dtr) or of the mating pair formation (Mpf) system, we analyzed the corresponding derivatives with respect to mobilization of IncQ plasmids and donor-specific phage propagation. We found that all of the Tra2 genes listed above and the traG and traF genes of Tra1 are required for RSF1010 mobilization. Expression of traF from Tra1 in conjunction with the Tra2 core was sufficient for phage propagation. This implies that the TraG protein is not directly involved in pilus formation and potentially connects the relaxosome with proteins enabling the membrane passage of the DNA. The proposed roles of the RP4 transfer gene products are discussed in the context of virulence functions encoded by the evolutionarily related Ti T-DNA transfer system of agrobacteria.

Base Sequence↗
PubMed1994

Linkage of mating-type loci distinguishes bipolar from tetrapolar mating in basidiomycetous smut fungi.

Sexual compatibility requires self vs. non-self recognition. Genetically, two compatibility or mating-type systems govern recognition in heterothallic basidiomycete fungi such as the edible and woodrotting mushrooms and the economically important rust and smut phytopathogens. A bipolar system is defined by a single genetic locus (MAT) that can have two or multiple alleles. A tetrapolar system has two loci, each with two or more specificities. We have employed two species from the genus Ustilago (smut fungi) to discover a molecular explanation for the genetic difference in mating systems. Ustilago maydis, a tetrapolar species, has two genetically unlinked loci that encode the distinct mating functions of cell fusion (a locus) and subsequent sexual development and pathogenicity (b locus). We have recently described a b locus in a bipolar species, Ustilago hordei, wherein the existence of an a locus has been suspected, but not demonstrated. We report here the cloning of an allele of the a locus (a1) from U. hordei and the discovery that physical linkage of the a and b loci in this bipolar fungus accounts for the distinct mating system. Linkage establishes a large complex MAT locus in U. hordei; this locus appears to be in a region suppressed for recombination.

Alleles↗
PubMed1999

Drosophila seminal fluid proteins enter the circulatory system of the mated female fly by crossing the posterior vaginal wall.

Seminal fluid proteins from males of many insect species affect the behavior and physiology of their mates. In some cases, these effects result from entry of the proteins into the female's circulatory system. In the fruit fly Drosophila melanogaster, some seminal fluid proteins enter the female's circulatory system after transfer from the male while others remain confined within the reproductive tract. To address where and how seminal fluid proteins enter the hemolymph of the mated female, we compared the kinetics of transfer and localization in mated females of two seminal fluid proteins that enter the hemolymph (Acp26Aa and Acp62F) and one that does not (Acp36DE). We also generated transgenic flies that produce Acp26Aa tagged with Aequorea victoria green fluorescent protein (GFP) to monitor its transfer in vivo. We report that Acps enter the female circulatory system from the posterior vagina immediately after insemination. The ability of Acps to enter the female hemolymph correlates with their ability to cross the intima that lines the posterior vagina. The ventral posterior vagina is structurally unlike other parts of the female reproductive tract in that it lacks muscles. We hypothesize that it has higher permeability thus affording access to the female's circulatory system.

Animals↗
PubMed2001

Specification of germ cell fates by FOG-3 has been conserved during nematode evolution.

Rapid changes in sexual traits are ubiquitous in evolution. To analyze this phenomenon, we are studying species of the genus Caenorhabditis. These animals use one of two different mating systems-male/hermaphroditic, like the model organism Caenorhabditis elegans, or male/female, like C. remanei. Since hermaphrodites are essentially females that produce sperm for self-fertilization, elucidating the control of cell fate in the germ line in each species could provide the key to understanding how these mating systems evolved. In C. elegans, FOG-3 is required to specify that germ cells become sperm. Thus, we cloned its homologs from both C. remanei and C. briggsae. Each species produces a single homolog of FOG-3, and RNA-mediated interference indicates that FOG-3 functions in each species to specify that germ cells develop as sperm rather than as oocytes. What factors account for the different mating systems? Northern analyses and RT-PCR data reveal that the expression of fog-3 is always correlated with spermatogenesis. Since the promoters for all three fog-3 genes contain binding sites for the transcription factor TRA-1A and are capable of driving expression of fog-3 in C. elegans hermaphrodites, we propose that alterations in the upstream sex-determination pathway, perhaps acting through TRA-1A, allow spermatogenesis in C. elegans and C. briggsae XX larvae but not in C. remanei.

Amino Acid Sequence↗
PubMed1998

Genetic and sequence analysis of the pTiC58 trb locus, encoding a mating-pair formation system related to members of the type IV secretion family.

Conjugal transfer of pTiC58 requires two regions, tra which contains the oriT and several genes involved in DNA processing and a region of undefined size and function that is located at the 2-o'clock position of the plasmid. Using transposon mutagenesis with Tn3HoHo1 and a binary transfer system, we delimited this second region, called trb, to an 11-kb interval between the loci for vegetative replication and nopaline catabolism. DNA sequence analysis of this region identified 13 significant open reading frames (ORFs) spanning 11,003 bp. The first, encoding traI, already has been described and is responsible for the synthesis of Agrobacterium autoinducer (AAI) (I. Hwang, P.-L. Li, L. Zhang, K. R. Piper, D. M. Cook, M. E. Tate, and S. K. Farrand, Proc. Natl. Acad. Sci. USA 91:4639-4643, 1994). Translation products of the next 11 ORFs showed similarities to those of trbB, -C, -D, -E, -J, -K, -L, -F, -G, -H, and -I of the trb region of the octopine-type Ti plasmid pTi15955 and of the tra2 core region of RP4. In RP4, these genes encode mating-pair formation functions and are essential for the conjugal transfer of the IncP plasmid. Each of the trb gene homologues is oriented counterclockwise on the Ti plasmid. Expression of these genes, as measured by using the lacZ fusions formed by Tn3HoHo1, required the traI promoter and the transcriptional activator TraR along with its coinducer, AAI. While related to that of RP4, the trb system of pTiC58 did not allow propagation of the trb-specific bacteriophages PRD1, PRR1, and Pf3. The products of several trb genes of the Ti plasmid are similar to those of other loci that encode DNA transfer or protein secretion systems, all of which are members of the type IV secretion family.

Agrobacterium tumefaciens↗
PubMed1984

Internal mis-mating of breathing system components.

A patient anaesthetized for bronchoscopy could not be ventilated when components of the breathing system met too closely and prevented the out flow of expired gas. This type of obstruction within the system may occur in the Ayre's T-piece, and when "low dead space" mask angles or co-axial systems are used with "low dead space" tracheal connectors or bronchoscopes. The problem is especially dangerous because it is not easily identified and subjects the patient to a very high airway pressure.

Aged↗
PubMed1997

Two types of alpha-factor receptor determinants for pheromone specificity in the mating-incompatible yeasts S. cerevisiae and S. kluyveri.

The specificity of mating-pheromone systems helps prevent mating between different species of yeast. The mechanism of specificity of G protein-coupled receptors in other organisms may be similar. To determine the structural basis of species discrimination between alpha-factor variants, small extracellular segments of the Saccharomyces cerevisiae alpha-factor receptor were substituted with residues from the Saccharomyces kluyveri alpha-factor receptor. Three substitutions altered specificity towards S. cerevisiae and S. kluyveri alpha-factor pheromone peptides. A substitution at residues 47-49 affected specificity for pheromone binding but not for pheromone activation of response. Substitution of residues 267-269 affected pheromone specificity for activation of cellular responses, but not for pheromone binding (under the assay conditions used). Substitution of residues 104-123 modestly affected both types of specificity. These results suggest two distinct types of receptor/ligand specificity (perhaps corresponding to ligand binding to G protein-coupled or uncoupled conformational states of the receptor) that evolved independently as S. cerevisiae and S. kluyveri diverged as species.

Binding Sites↗
PubMed2004

Intratetrad mating and the evolution of linkage relationships.

Mating among the immediate products of meiosis (intratetrad mating) is a common feature of many organisms with parthenogenesis or with mating-type determination in the haploid phase. Using a three-locus deterministic model we show that intratetrad mating, unlike other systems of mating, allows sheltering of deleterious recessive alleles even if there is only partial linkage between a mating locus and a load locus. Moreover, modifiers that reduce recombination between the load and mating-type locus will spread to fixation, even when there is no linkage disequilibrium between these loci in the population as a whole. This seeming contradiction to classical expectation is because partial linkage generates linkage disequilibrium among segregating loci within a tetrad, which then acts as the "mating unit."

Alleles↗
PubMed1999

Evolution of the genetic covariance between male and female components of mate recognition: an experimental test.

The evolution of a positive genetic correlation between male and female components of mate recognition systems will result as a consequence of assortative mating and, in particular, is central to a number of theories of sexual selection. Although the existence of such genetic correlations has been investigated in a number of taxa, it has yet to be shown that such correlations evolve and whether they may evolve as rapidly as suggested by sexual selection models. In this study, I used a hybridization experiment to disrupt natural mate recognition systems and then observed the subsequent evolutionary dynamics of the genetic correlation between male and female components for 56 generations in hybrids between Drosophila serrata and Drosophila birchii. The genetic correlation between male and female components evolved from 0.388 at generation 5 to 1.017 at generation 37 and then declined to -0.040 after a further 19 generations. These results indicated that the genetic basis of the mate recognition system in the hybrid populations evolved rapidly. The initial rapid increase in the genetic correlation was consistent with the classic assumption that male and female components will coevolve under sexual selection. The subsequent decline in genetic correlation may be attributable to the fixation of major genes, or, alternatively, may be a result of a cyclic evolutionary change in mate recognition.

Animals↗
PubMed2001

Polyandry in Lepidoptera: a heritable trait in Spodoptera exigua Hübner.

The genetic basis as well as the mode of inheritance of polyandry in Spodoptera exigua Hübner was studied in the laboratory by using a simple divergent selection experiment followed by F1 reciprocal crosses, F2 and backcrosses. There was an effective response to artificial selection for high (H line) and low (L line) female mating frequency with significant separation of the lines by the second generation of selection. The mean female mating frequency in the parental generation (1.57 matings per female) reached plateaus of 2.50 and 1.25 matings per female in the H and L lines, respectively, after six generations of selection. Selection response becomes saturated at about 90% and 25% levels of polyandry (percentage females re-mating) in the H and L lines, respectively, and consequently mono- and polyandric pure strains were not obtained. Polyandry levels in offspring from the H and L lines and their hybrids in F1, F2 and backcrosses consistently indicate that female mating frequency was more or less proportional to the relative amounts of genes derived from the H and L lines. Such a clear pattern of hybrid responses, together with the gradual selective changes under artificial selection, suggests the involvement of a polygenic system. Female mating frequencies from progeny of the two reciprocal F1 crosses were not significantly different, which suggest that the trait was autosomally inherited. Moreover, female mating frequency of F1 (pooled) progeny was not significantly different from the mid-parental value, which suggest no dominance. The computation of the Cavalli's joint scaling test consistently confirmed these results yielding values of d = 0.51 +/- 0.10 and h = 0.12 +/- 0.21. The broad sense heritability estimate was H2 = 0.73. It is concluded that polyandry in S. exigua is a polygenic, autosomal heritable trait and that additive genetic variance is available for selection for female mating frequency. The implications of the genetic basis of polyandry are briefly discussed in the context of current theories about this crucial insect mating system.

Animals↗
PubMed1981

Preferential mating in symmetric multilocus systems.

A class of multilocus models that incorporate both preferential mating and viability selection is studied. Symmetry in alleles is supposed, resulting in the phenotypes being dependent only on the location of heterozygous loci. Otherwise, an arbitrary number of loci, number of alleles per locus, and arbitrary recombination schemes, viability parameters, and preferential mating pattern are allowed. The conditions for stability of a central polymorphism, c(*), are indicated and interpreted. Mating and viability parameters enter as one combined quantity for each phenotypic class, which represents a generalized fitness. The effect on stability of c(*) of increasing the number of alleles per locus and the number of loci requires the formulation to be set in terms of frequency-dependent preference parameters.

Journal Article↗
PubMed1995

Mating behaviour in mixed infections of Schistosoma haematobium and S. mattheei.

In mixed infections of Schistosoma haematobium and S. mattheei, homospecific and heterospecific pairs are formed, with a preponderance of homospecific pairs indicating the existence of a mate preference system. S. haematobium apparently exhibits a greater specific mate recognition system than does S. mattheei. In sequential infections when mice are exposed to S. mattheei 4 weeks after infection with S. haematobium, S. haematobium males are better at pairing with S. mattheei females than are S. mattheei males. Hence, genetic exchanges between S. haematobium and S. mattheei giving rise to viable hybrids poses the problem of the genetic identity of these species of schistosomes. The most important reproductive isolating mechanisms are definitive host specificity, S. haematobium being primarily a parasite of man, whereas S. mattheei is a parasite of domestic stock and wild ungulates, and the preference for homospecific pairings in simultaneous infections. In contrast, when S. haematobium is the older infection, S. haematobium males are better than S. mattheei males at pairing with females of either species. Hybridisation is the likely outcome of such interactions. The lack of viability of S. mattheei male X S. haematobium female indicates genetic differences between the two species. Occurrences of natural hybridisation between S. haematobium and S. mattheei may lead to a change in the response of the parasite to chemotherapeutic treatment.

Animals↗
PubMed2003

Interactions between Schistosoma intercalatum (Zaire strain) and S. mansoni.

Schistosoma mansoni and S. intercalatum, two schistosomes from different evolutionary lineages, are parasitic in humans and therefore able to co-infect the same host where they occur sympatrically in Africa. Previous studies of mating interactions between these species in mice, using the Lower Guinea strain of S. intercalatum, have demonstrated the competitive dominance of S. mansoni over S. intercalatum in terms of pairing ability, which is potentially an important mechanism restricting the distribution of S. intercalatum in Africa. The study presented here examines the mating interactions in mice between S. mansoni and the Zaire (Democratic Republic of Congo) strain of S. intercalatum, which differs from the Lower Guinea strain in many biological characteristics. Analysis of the data showed a preponderance of intraspecific pairs over interspecific, demonstrating a specific mate preference system for both species. Mating competition between these species and the ability of males of both species to effect a change of mate by pulling paired females away from their partners was indicated. Comparisons are made between the competitive mating abilities of both strains of S. intercalatum relative to those of S. mansoni, with the data suggesting that S. mansoni is competitively dominant to S. intercalatum (Zaire) in sequential infections but to a lesser extent than for S. intercalatum (Lower Guinea). Additional factors which may contribute to the confinement of S. intercalatum (Zaire) to the Democratic Republic of Congo are discussed.

Animals↗
PubMed1995

Fungal lipopeptide mating pheromones: a model system for the study of protein prenylation.

In a variety of fungal species, mating between haploid cells is initiated by the action of peptide pheromones. The identification and characterization of several fungal pheromones has revealed that they have common structural features classifying them as lipopeptides. In the course of biosynthesis, these pheromones undergo a series of posttranslational processing events prior to export. One common modification is the attachment of an isoprenoid group to the C terminus of the pheromone precursor. Genetic and biochemical investigations of this biosynthetic pathway have led to the elucidation of genes and enzymes which are responsible for isoprenylation of other polypeptides including the nuclear lamins, several vesicular transport proteins, and the oncogene product Ras. The alpha-factor of Saccharomyces cerevisiae serves as a model for studying the biosynthesis, export, and bioactivity of lipopeptide pheromones. In addition to being isoprenylated with a farnesyl group, the alpha-factor is secreted by a novel peptide export pathway utilizing a yeast homolog of the mammalian multidrug resistance P-glycoprotein. The identification of putative lipopeptide-encoding loci within other fungi, including the human immunodeficiency virus-associated opportunistic pathogen Cryptococcus neoformans and the plant pathogen Ustilago maydis, has stimulated much interest in understanding possible roles for pheromones in fungal proliferation and pathogenicity. Knowledge of variations within the processing, export, and receptor-mediated signal transduction pathways associated with different fungal lipopeptide pheromones will continue to provide insights into similar mechanisms which exist in higher eukaryotes.

Amino Acid Sequence↗
PubMed2005

Advertisement-call preferences in diploid-tetraploid treefrogs (Hyla chrysoscelis and Hyla versicolor): implications for mate choice and the evolution of communication systems.

Signals used for mate choice and receiver preferences are often assumed to coevolve in a lock-step fashion. However, sender-receiver coevolution can also be nonparallel: even if species differences in signals are mainly quantitative, females of some closely related species have qualitatively different preferences and underlying mechanisms. Two-alternative playback experiments using synthetic calls that differed in fine-scale temporal properties identified the receiver criteria in females of the treefrog Hyla chrysoscelis for comparison with female criteria in a cryptic tetraploid species (H. versicolor); detailed preference functions were also generated for both species based on natural patterns of variation in temporal properties. The species were similar in three respects: (1) pulses of constant frequency were as attractive as the frequency-modulated pulses typical of conspecific calls; (2) changes in preferences with temperature paralleled temperature-dependent changes in male calls; and (3) preference functions were unimodal, with weakly defined peaks estimated at values slightly higher than the estimated means in conspecific calls. There were also species differences: (1) preference function slopes were steeper in H. chrysoscelis than in H. versicolor; (2) preferences were more intensity independent in H. chrysoscelis than in H. versicolor; (3) a synergistic effect of differences in pulse rate and shape on preference strength occurred in H. versicolor but not in H. chrysoscelis; and (4) a preference for the pulse shape typical of conspecific calls was expressed at the species-typical pulse duration in H. versicolor but not in H. chrysoscelis. However, females of H. chrysoscelis did express a preference based on pulse shape when tested with longer-than-average pulses, suggesting a hypothesis that could account for some examples of nonparallel coevolution. Namely, preferences can be hidden or revealed depending on the direction of quantitative change in a signal property relative to the threshold for resolving differences in that property. The results of the experiments reported here also predict patterns of mate choice within and between contemporary populations. First, intraspecific mate choice in both species is expected to be strongly influenced by variation in temperature among calling males. Second, simultaneous differences in pulse rate and pulse shape are required for effective species discrimination by females of H. versicolor but not by females of H. chrysoscelis. Third, there is greater potential for sexual selection within populations and for discrimination against calls produced by males in other geographically remote populations in H. chrysoscelis than in H. versicolor.

Acoustic Stimulation↗
PubMed1995

Effective size of populations under selection.

Equations to approximate the effective size (Ne) of populations under continued selection are obtained that include the possibility of partial full-sib mating and other systems such as assortative mating. The general equation for the case of equal number of sexes and constant number of breeding individuals (N) is Ne = 4N/[2(1 - alpha I) + (Sk2 + 4Q2C2) (1 + alpha I + 2 alpha O)], where Sk2 is the variance of family size due to sampling without selection, C2 is the variance of selective advantages among families (the squared coefficient of variation of the expected number of offspring per family), alpha I is the deviation from Hardy-Weinberg proportions, alpha O is the correlation between genes of male and female parents, and Q2 is the term accounting for the cumulative effect of selection on an inherited trait. This is obtained as Q = 2/[2 - G(1 + r)], where G is the remaining proportion of genetic variance in selected individuals and r is the correlation of the expected selective values of male and female parents. The method is also extended to the general case of different numbers of male and female parents. The predictive value of the formulae is tested under a model of truncation selection with the infinitesimal model of gene effects, where C2 and G are a function of the selection intensity, the heritability and the intraclass correlation of sibs. Under random mating r = alpha I = -1/(N - 1) and alpha O = 0. Under partial full-sib mating with an average proportion beta of full-sib matings per generation, r approximately beta and alpha O approximately alpha I approximately beta/(4 - 3 beta). The prediction equation is compared to other approximations based on the long-term contributions of ancestors to descendants. Finally, based on the approach followed, a system of mating (compensatory mating) is proposed to reduce rates of inbreeding without loss of response in selection programs in which selected individuals from the largest families are mated to those from the smallest families.

Animals↗
PubMed2002

Interaction between natural and sexual selection during the evolution of mate recognition.

The interaction between natural and sexual selection is central to many theories of how mate choice and reproductive isolation evolve, but their joint effect on the evolution of mate recognition has not, to my knowledge, been investigated in an evolutionary experiment. Natural and sexual selection were manipulated in interspecific hybrid populations of Drosophila to determine their effects on the evolution of a mate recognition system comprised of cuticular hydrocarbons (CHCs). The effect of natural selection in isolation indicated that CHCs were costly for males and females to produce. The effect of sexual selection in isolation indicated that females preferred males with a particular CHC composition. However, the interaction between natural and sexual selection had a greater effect on the evolution of the mate recognition system than either process in isolation. When natural and sexual selection were permitted to operate in combination, male CHCs became exaggerated to a greater extent than in the presence of sexual selection alone, and female CHCs evolved against the direction of natural selection. This experiment demonstrated that the interaction between natural and sexual selection is critical in determining the direction and magnitude of the evolutionary response of the mate recognition system.

Animals↗