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PubMed1996

The ovarian follicular wave pattern and induction of ovulation in the mated and non-mated one-humped camel (Camelus dromedarius).

Ovarian follicular wave patterns were studied ultrasonographically in three groups of dromedary. Group 1 camels (n = 20) were teased daily with a vasectomized male but mating was prevented; group 2 camels (n = 8) ran freely with a vasectomized male camel for 10 h each day and group 3 camels (n = 8) were kept completely separate from any males. In a second experiment (n = 63), when the diameter of the dominant follicle reached 0.5-0.9 cm, 1.0-1.9 cm, 2.0-2.9 cm or > 3 cm, the camel was given one of three treatments to induce ovulation: (i) natural mating; (ii) 20 micrograms of the GnRH analogue, buserelin; or (iii) 3000 iu hCG. The ovaries were re-scanned regularly to monitor ovulation, and daily blood samples were assayed for progesterone and oestradiol concentrations. The follicular cycle was divisible into a growth phase (10.5 +/- 0.5 days), a mature phase (7.6 +/- 0.8 days) and a regression phase (11.9 +/- 0.8 days). The dominant follicle reached a mean +/- SEM maximum diameter of 2.0 +/- 0.1 cm (range 1.5-2.5 cm) in 34 cycles (52%) before it began to regress. In the other 32 cycles (48%), however, the dominant follicle continued to grow to 4.2 +/- 0.2 cm (range 4.0-6.0 cm) before regression commenced. Group 2 camels were mated when their follicles reached 1.3 +/- 0.1 cm in diameter and the mean interval between successive matings was 13.8 +/- 1.0 days. Mean +/- SEM serum concentrations of oestradiol reached peak values at 39.0 +/- 1.8 pg ml-1, when the dominant follicle measured 1.7 +/- 0.1 cm and, after ovulation, mean serum concentrations of progesterone reached peak values at 2.6 +/- 0.3 ng ml-1 on day 8, before decreasing to < 1 ng ml-1 by day 10 or 11. When the dominant follicle measured 0.5-0.9 cm in diameter, 70%, 60% and 60% of them ovulated in response to mating, or treatment with buserelin or hCG, respectively. These ovulation rates increased to 85% (mating), 81% (buserelin) and 67% (hCG) when the follicle measured 1-1.9 cm, but they decreased again to 12.5% (mating), 29% (buserelin) and 13% (hCG) when the diameter had increased to 2.0-2.9 cm at the time of treatment. No follicles measuring > 3.0 cm ovulated in response to any of the treatments. These results indicated that the optimum time to mate or attempt to induce ovulation in the female dromedary is when the growing follicle measures 0.9-1.9 cm in diameter.

Animals↗

PubMed2005

Evidence for minority male mating success and minority female mating disadvantage in Drosophila ananassae.

Frequency-dependent mating success was tested for three pairs of wild-type and mutant strains of Drosophila ananassae, MY and yellow body color (y), PN and claret eye color (ca), and TIR and cut wing (ct). The two strains of each pair were chosen for their approximately equal mating propensities. Multiple-choice experiments, using different experimental procedures, were employed. The tests were carried out by direct observation in Elens-Wattiaux mating chambers with five different sex ratios (4:16, 8:12, 10:10, 12:8, and 16:4). There was no assortative mating and sexual isolation between the strains, based on 2 x 2 contingency chi2 analysis and isolation estimate values. One-sided rare male mating advantages were found in two experiments, one for ca males and the other for wild-type males (TIR). However, no advantage was found for rare males in the experiment with MY and y flies. Mating disadvantages for rare females were found for sex-linked mutants (y and ct). Two different observational methods (removal or direct observation of mating pairs) imparted no overall significant effects on the outcome of the frequency-dependent mating tests.

Animals↗

PubMed2004

Mating-type locus homozygosis, phenotypic switching and mating: a unique sequence of dependencies in Candida albicans.

A small proportion of clinical strains of Candida albicans undergo white-opaque switching. Until recently it was not clear why, since most strains carry the genes differentially expressed in the unique opaque phase. The answer to this enigma lies in the mating process. The majority of C. albicans strains are heterozygous for the mating type locus MTL (a/alpha) and cannot undergo white-opaque switching. However, when these cells undergo homozygosis at the mating type locus (i.e., become a/a or alpha/alpha), they can switch, and they must switch in order to mate. Even though the newly identified stages of mating mimic those of Saccharomyces cerevisiae, the process differs in its dependency on switching, and the effects switching has on gene regulation. This unique feature of C. albicans mating appears to be intimately intertwined with its pathogenesis. The unique, newly discovered dependencies of switching on homozygosis at the MTL locus and of mating on switching are, therefore, reviewed within the context of pathogenesis.

Alleles↗

PubMed2005

Male mate choice and sperm allocation in a sexual/asexual mating complex of Poecilia (Poeciliidae, Teleostei).

Male mate choice is critical for understanding the evolution and maintenance of sexual/asexual mating complexes involving sperm-dependent, gynogenetic species. Amazon mollies (Poecilia formosa) require sperm to trigger embryogenesis, but the males (e.g. Poecilia mexicana) do not contribute genes. Males benefit from mating with Amazon mollies, because such matings make males more attractive to conspecific females, but they might control the cost of such matings by providing less sperm to Amazon mollies. We examined this at the behavioural and sperm levels. P. mexicana males preferred to mate with, and transferred more sperm to conspecific females. However, if males mated with P. formosa, sperm was readily transferred. This underscores the importance of male choice in this system.

Animals↗

PubMed2005

Isolation and characterization of the mating-type locus of the barley pathogen Pyrenophora teres and frequencies of mating-type idiomorphs within and among fungal populations collected from barley landraces.

Pyrenophora teres f. sp. teres mating-type genes (MAT-1: 1190 bp; MAT-2: 1055 bp) have been identified. Their predicted proteins, measuring 379 and 333 amino acids, respectively, are similar to those of other Pleosporales, such as Pleospora sp., Cochliobolus sp., Alternaria alternata, Leptosphaeria maculans, and Phaeosphaeria nodorum. The structure of the MAT locus is discussed in comparison with those of other fungi. A mating-type PCR assay has also been developed; with this assay we have analyzed 150 isolates that were collected from 6 Sardinian barley landrace populations. Of these, 68 were P. teres f. sp. teres (net form; NF) and 82 were P. teres f. sp. maculata (spot form; SF). Within each mating type, the NF and SF amplification products were of the same length and were highly similar in sequence. The 2 mating types were present in both the NF and the SF populations at the field level, indicating that they have all maintained the potential for sexual reproduction. Despite the 2 forms being sympatric in 5 fields, no intermediate isolates were detected with amplified fragment length polymorphism (AFLP) analysis. These results suggest that the 2 forms are genetically isolated under the field conditions. In all of the samples of P. teres, the ratio of the 2 mating types was consistently in accord with the 1:1 null hypothesis. This ratio is expected when segregation distortion and clonal selection among mating types are absent or asexual reproduction is rare. Overall, sexual reproduction appears to be the major process that equalizes the frequencies of the 2 mating types within populations.

Amino Acid Sequence↗

PubMed1997

Differential effects of mate competition and mate choice on eastern tiger salamanders

Male tiger salamanders, Ambystoma tigrinum tigrinumare slightly larger in body size and have considerably higher and longer tails than females. To determine how these dimorphic traits affected reproductive performance and success, we conducted breeding trials using 12 males and six females per trial and monitored male-female and male-male interactions. Larger males had an advantage in most aspects of mate competition investigated. Males with higher tails had no advantage in either mate competition or mate choice. Males with longer tails also had no advantage in mate competition but were preferred as mates by females. Larger males interrupted courting males more often than smaller males did. The form of male-male interference was conditional on body size and not on either tail dimension. If the intruder was larger than the courting male, it would shove the female away from the courting male and initiate courtship; if the intruder was smaller, it adopted a female mimicry tactic in which it positioned itself between the courting male and female and performed female behaviours to the courting male while simultaneously courting the female. Our trials indicated that the two components of sexual selection may influence the evolution of different male morphological traits in tiger salamanders. Mate competition may favour increased male body length; mate choice may select for greater male tail length.

Journal Article↗

PubMed1997

Mate choice and competition for mates in the boat-tailed grackle

Behavioural studies have implicated both female choice of mates and male competition for access to mates as proximate mechanisms of sexual selection. Few studies have examined the interactions between these mechanisms in a natural setting. In this study, I explored how dominance interactions between male boat-tailed grackles, Quiscalus majordetermine the mating success of males and how the behaviour of female boat-tailed grackles influences this process. Male grackles defended colonies of females and performed courtship displays to females that were building nests. These conspicuous displays incited dominance interactions between males, with the result that dominant males interrupted subordinate males' attempts to copulate. Female grackles were receptive only to males that performed courtship displays, but their receptivity to males did not vary with male dominance rank or tail length. Females were more likely to be receptive in a colony than away from a colony, and females became receptive asynchronously during the breeding season. The timing and spacing of females' receptivity to males permitted dominance interactions between males to determine male mating success. By establishing the conditions for male competition, females indirectly chose high-ranking males. Recent studies have emphasized discrimination among potential mates as a behavioural mechanism for mate choice. The results reported here, however, demonstrate that other aspects of females' behaviour can produce mate choice, indirectly rather than directly.1997The Association for the Study of Animal Behaviour

Journal Article↗

PubMed1995

Conjugation in the ciliate Euplotes octocarinatus: comparison of ciliary and cell body-associated glycoconjugates of non-mating-competent, mating-competent, and conjugating cells.

Pair formation in the hypotrichous ciliate Euplotes octocarinatus is a poorly understood phenomenon. In order to obtain information about the molecules involved in this process, we compared ciliary and cell body-associated glycoconjugates of non-mating-competent, mating-competent, and conjugating cells. Detection of glycoconjugates was carried out on Western blots by immunostaining of oxidized, digoxigenin-labeled carbohydrate moieties. Using this method, in both of two complementary mating types a 130-kDa glycoprotein was identified, which appeared on cilia during acquisition of mating competence and was reduced during cell pairing. This suggests an active role of this glycoprotein in ciliary adhesion during pair formation. Additionally, in both of the two mating types a cell body-associated 135-kDa glycoprotein was detected, which is present in non-mating-competent cells as well as in mating-competent cells, but is strongly reduced in conjugating cells. In contrast to the ciliary 130-kDa glycoprotein, the cell body-associated 135-kDa glycoprotein is not surface-exposed [8]. We therefore propose that the cell body-associated glycoprotein is either involved in the preparation for cell fusion or meiosis or that it serves as a cytoplasmic pool for the ciliary 130-kDa glycoprotein.

Animals↗

PubMed1975

The mating reaction in yeast. I. A new mutation involved in the determination of mating-type.

The isolation and preliminary characterisation of a mutation, not linked to the mating type locus, but which apparently alters the mating type directed sequence of events during sexual conjugation is described. Haploids of the alpha mating type carrying this gene will now mate with other alpha haploids, creating diploids homozygous for the alpha mating type locus. This gene can be carried, but not expressed, in a haploids, however in a/alpha diploids homozygous for this gene mating is now possible with both a and alpha haploids giving either a/a/alpha or a/alpha/alpha triploids. Using these strains mating-deficient mutants have been isolated and preliminary results on their characterisation presented.

Conjugation, Genetic↗

PubMed2000

Deletion of the MAT-2 mating-type gene during uni-directional mating-type switching in Ceratocystis.

Ceratocystis eucalypti is strictly heterothallic, with single ascospore strains representing one of two opposite mating types. Most other Ceratocystis species, including C. virescens, C. pinicola, and C. fimbriata, are homothallic. In the homothallic species, the MAT-2 strains are self-fertile, while MAT-1 strains are self-sterile and grow more slowly than MAT-2 strains. The current hypothesis is that self-fertility of MAT-2 strains is due to the deletion of the MAT-2 mating-type gene, resulting in the expression of the MAT-1 mating type. These mutant MAT-1 strains are able to cross with MAT-2 strains. Part of the MAT-2 mating-type gene in C. eucalypti, C. pinicola, and C. fimbriata was amplified using degenerate primers designed from the conserved MAT-2 HMG DNA-binding motif. The expected approximately 300-bp PCR products were cloned and sequenced. Specific primers were designed that amplified 210-bp fragments only in MAT-2 isolates of C. eucalypti, C. virescens, C. pinicola, and C. finbriata. These fragments were present in self-fertile field isolates and self-fertile progeny but were absent in the self-sterile (MAT-1) progeny from selfings of C. virescens, C. pinicola, and C. fimbriata, thus supporting the hypothesis that the MAT-2 mating-type gene is deleted during uni-directional mating-type switching. A Southern-blot analysis was performed to confirm the deletion of MAT-2 gene in self-sterile progeny. The DNA sequence data for the C. eucalypti MAT-2 mating-type gene was increased to 1371-bp using TAIL-PCR and uneven PCR, representing a portion of the complete MAT-2 gene DNA sequence.

Amino Acid Sequence↗

PubMed1996

The Schizosaccharomyces pombe mra1 gene, which is required for cell growth and mating, can suppress the mating inefficiency caused by a deficit in the Ras1 activity.

BACKGROUND: Schizosaccharomyces pombe Ras1 regulates two downstream pathways, namely the Byr2/Byr1/Spk1 mitogen-activated protein kinase cascade and the Cdc42sp small G protein pathway. The former is relevant to mating and sporulation, whereas the latter is relevant to mating, cell growth and cell morphology. We addressed whether Ras1 has any additional role in the regulation of cell physiology. RESULTS: Using a specific mutation in the effector region of Ras1, we isolated a high-copy-number suppressor of the mating deficiency caused by a decrease of the Ras1 activity. The isolated gene, named mra1, encodes a novel protein of 359 amino acids, which has apparent homologues in rice and budding yeast. Disruption of mra1 indicated that it is essential for cell growth, and mutational analysis indicated that it is required for the promotion of mating. These two functions could be separated by mutations, suggesting that Mra1 is bifunctional. Overexpression of mra1 could also suppress the mating inefficiency caused by either overexpression of gap1, which is a downregulator of Ras1, or loss of function of zfs1, which is a gene relevant to the mating pheromone signalling. However, it could not suppress null mutations in genes involved in the two known pathways downstream of Ras1. CONCLUSIONS: Mra1 is an apparent downstream factor of Ras1, which is essential for cell growth and relevant to mating but is not involved in the maintenance of cell morphology. Mra1 is unlikely to interact directly with the known pathways downstream of Ras1, implying that it may be a factor constituting a third pathway regulated by Ras1.

Amino Acid Sequence↗

PubMed2003

Cognitive processes underlying human mate choice: The relationship between self-perception and mate preference in Western society.

This study tested two hypotheses concerning the cognitive processes underlying human mate choice in Western society: (i) mate preference is conditional in that the selectivity of individuals' mate preference is based on their perception of themselves as long-term partners, and (ii) the decision rule governing such conditional mate preference is based on translating perception of oneself on a given attribute into a comparable selectivity of preference for the same attribute in a mate. Both hypotheses were supported. A two-part questionnaire was completed by 978 heterosexual residents of Ithaca, New York, aged 18-24; they first rated the importance they placed on 10 attributes in a long-term partner and then rated their perception of themselves on those same attributes. Both women and men who rated themselves highly were significantly more selective in their mate preference. When the 10 attributes were grouped into four evolutionarily relevant categories (indicative of wealth and status, family commitment, physical appearance, and sexual fidelity), the greatest amount of variation in the selectivity of mate preference in each category was explained by self-perception in the same category of attributes. We conclude that, in Western society, humans use neither an "opposites-attract" nor a "reproductive-potentials-attract" decision rule in their choice of long-term partners but rather a "likes-attract" rule based on a preference for partners who are similar to themselves across a number of characteristics.

Adolescent↗

PubMed2002

Molecular genetic analyses of mating pheromones reveal intervariety mating or hybridization in Cryptococcus neoformans.

The sexual mating of the pathogenic yeast Cryptococcus neoformans is important for pathogenesis studies because the fungal virulence is linked to the alpha mating type (MAT(alpha)). We characterized C. neoformans mating pheromones (MF(alpha) 1 and MFa1) from 122 strains to understand intervariety hybridization or mating and intervariety virulence. MF(alpha) 1 in three C. neoformans varieties showed (a) specific nucleotide polymorphisms, (b) different copy numbers and chromosomal localizations, and (c) unique deduced amino acids in two geographic populations of C. neoformans var. gattii. MF(alpha) 1 of different varieties cross-hybridized in Southern hybridizations. Their phylogenetic analyses showed purifying selection (neutral evolution). These observations suggested that MAT(alpha) strains from any of the three C. neoformans varieties could mate or hybridize in nature with MATa strains of C. neoformans var. neoformans. A few serotype A/D diploid strains provided evidence for mating or hybridization, while a majority of A/D strains tested positive for haploid MF(alpha) 1 identical to that of C. neoformans var. grubii. MF(alpha) 1 sequence and copy numbers in diploids were identical to those of C. neoformans var. grubii, while their MFa1 sequences were identical to those of C. neoformans var. neoformans; thus, these strains were hybrids. The mice survival curves and histological lesions revealed A/D diploids to be highly pathogenic, with pathogenicity levels similar to that of the C. neoformans var. grubii type strain and unlike the low pathogenicity levels of C. neoformans var. neoformans strains. In contrast to MF(alpha) 1 in three varieties, MFa1 amplicons and hybridization signals could be obtained only from two C. neoformans var. neoformans reference strains and eight A/D diploids. This suggested that a yet undiscovered MFa pheromone(s) in C. neoformans var. gattii and C. neoformans var. grubii is unrelated to, highly divergent from, or rarer than that in C. neoformans var. neoformans. These observations could form the basis for future studies on the role of intervariety mating in C. neoformans biology and virulence.

Animals↗

PubMed2006

Assortative mating and differential male mating success in an ash hybrid zone population.

BACKGROUND: The structure and evolution of hybrid zones depend mainly on the relative importance of dispersal and local adaptation, and on the strength of assortative mating. Here, we study the influence of dispersal, temporal isolation, variability in phenotypic traits and parasite attacks on the male mating success of two parental species and hybrids by real-time pollen flow analysis. We focus on a hybrid zone population between the two closely related ash species Fraxinus excelsior L. (common ash) and F. angustifolia Vahl (narrow-leaved ash), which is composed of individuals of the two species and several hybrid types. This population is structured by flowering time: the F. excelsior individuals flower later than the F. angustifolia individuals, and the hybrid types flower in-between. Hybrids are scattered throughout the population, suggesting favorable conditions for their local adaptation. We estimate jointly the best-fitting dispersal kernel, the differences in male fecundity due to variation in phenotypic traits and level of parasite attack, and the strength of assortative mating due to differences in flowering phenology. In addition, we assess the effect of accounting for genotyping error on these estimations. RESULTS: We detected a very high pollen immigration rate and a fat-tailed dispersal kernel, counter-balanced by slight phenological assortative mating and short-distance pollen dispersal. Early intermediate flowering hybrids, which had the highest male mating success, showed optimal sex allocation and increased selfing rates. We detected asymmetry of gene flow, with early flowering trees participating more as pollen donors than late flowering trees. CONCLUSION: This study provides striking evidence that long-distance gene flow alone is not sufficient to counter-act the effects of assortative mating and selfing. Phenological assortative mating and short-distance dispersal can create temporal and spatial structuring that appears to maintain this hybrid population. The asymmetry of gene flow, with higher fertility and increased selfing, can potentially confer a selective advantage to early flowering hybrids in the zone. In the event of climate change, hybridization may provide a means for F. angustifolia to further extend its range at the expense of F. excelsior.

Evolution, Molecular↗

PubMed1987

Effects of plane of nutrition and phenobarbital during the pre-mating period on reproduction in ewes fed differentially during the summer and mated in the fall.

An increased plane of nutrition of ewes before mating (flushing) has been associated with an increased number of lambs per ewe. The following study was done to investigate a possible mechanism for the flushing effect. During the summer, 98 Hampshire and Suffolk ewes grazed pastures with 50 of the ewes supplemented with .45 kg of corn grain X head-1 X d-1. For approximately 12 d before fall mating, each ewe received daily either .45 kg of a corn grain-soybean oil meal mixture, an oral dose of 1 g phenobarbital or no treatment. Liver biopsies were collected from 23 ewes, representing all treatment combinations, 3 d after initiation of pre-mating treatment for determination of concentration of hepatic mixed function oxidase enzymes (MFO). Summer supplementation vs no summer supplementation resulted in ewes with heavier (P less than .05) body weights near mating (75.6 vs 71.1 kg), higher (P less than .01) mating condition scores (3.2 vs 2.9), a greater (P less than .01) number of ovulations (1.99 vs 1.74), but little difference (P greater than .10) in number of lambs born per ewe lambing. Pre-mating treatment with phenobarbital or grain mix resulted in a greater number of ovulations (P less than .01, P less than .10, respectively) than no pre-mating treatment (2.14, 1.85, 1.60; respectively). Ewes given phenobarbital had more (P less than .10) lambs per ewe than ewes given no treatment (1.71 vs 1.40). Both phenobarbital and grain mix resulted in a significant increase in concentration of MFO compared with no treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Nutritional Physiological Phenomena↗

PubMed1995

Acid phosphatase activity in mating type I and mating type II cell lines of Paramecium primaurelia.

The cellular acid phosphatase content, a marker enzyme for lysosomal activity, in Paramecium primaurelia mating type I and mating type II cells was determined by optical laser scanning microscopy. The naphthol AS-TR phosphatase-hexazotized pararosaniline method was used to visualize acid phosphatase activity by the light microscopy. Cell lines of both mating types were tested during culture life, from the early log phase to the death phase. The amount of acid phosphatase was higher in mating type II than in mating type I until the onset of the stationary phase, and then the values reversed. Indeed, during the log phase of growth, mating type II cells formed a higher number of food vacuoles, so that, by taking up a higher amount of bacteria, they sooner became deprived of food. It is suggested that, by lacking nutrients, their synthesis activities and acid phosphatase content were reduced as compared with mating type I cells.

Acid Phosphatase↗

PubMed2002

White-opaque switching in Candida albicans is controlled by mating-type locus homeodomain proteins and allows efficient mating.

Discovered over a decade ago, white-opaque switching in the human fungal pathogen Candida albicans is an alternation between two quasistable, heritable transcriptional states. Here, we show that white-opaque switching and sexual mating are both controlled by mating type locus homeodomain proteins and that opaque cells mate approximately 10(6) times more efficiently than do white cells. These results show that opaque cells are a mating-competent form of C. albicans and that this pathogen undergoes a white-to-opaque switch as a critical step in the mating process. As white cells are generally more robust in a mammalian host than are opaque cells, this strategy allows the organism to survive the rigors of life within a mammalian host, yet generate mating-competent cells.

Alleles↗

PubMed1998

Cloning of the mating type loci from Pyrenopeziza brassicae reveals the presence of a novel mating type gene within a discomycete MAT 1-2 locus encoding a putative metallothionein-like protein.

The mating type loci were cloned from Pyrenopeziza brassicae by chromosome walking from a mating type-linked polymerase chain reaction (PCR) fragment and shown to be idiomorphic by sequence analysis. The MAT 1-1 locus is approximately 3.2 kb and contains a single gene encoding a putative high-mobility group (HMG) domain protein. The MAT 1-2 locus is approximately 3.9 kb with three open reading frames (ORFs) encoding a putative HMG domain, an alpha-1 domain and metallothionein-like proteins. The putative alpha-1 domain ORF on MAT 1-2 is transcribed in the opposite orientation to the other two transcripts and extends into non-idiomorphic sequence. This is the first report of sequence analysis of the mating type loci from a discomycete fungus, which has revealed an interesting mating type infrastructure within the MAT 1-2 locus. Although metallothionein-like proteins have been implicated in a number of processes in animals and plants, they have not to date been implicated in the mating process of filamentous fungi. Possible roles for metallothionein-like proteins in the mating process are discussed.

Amino Acid Sequence↗