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PubMed1999

Paced mating behavior in female rats in response to different hormone priming regimens.

A female rat will display a repertoire of behaviors during a sexual encounter with a male rat including sexually receptive (the lordosis response) and proceptive (hopping, darting) behaviors. In addition, when given the opportunity, a sexually receptive female rat will approach and withdraw from the male rat, controlling the timing of the receipt of mounts, intromissions, and ejaculations, a behavior known as paced mating behavior. The present experiments tested the hypotheses (1) that progesterone regulates paced mating behavior, and (2) that multiple hormone regimens used previously to induce sexual receptivity have the same effect on paced mating behavior. Paced mating behavior was assessed in sexually receptive ovariectomized female rats after treatment with: (1) estradiol benzoate (EB; 30.0 mg/kg) followed by a range of doses of progesterone (P; 1.0-8.0 mg/kg), (2) two pulses of unesterified estradiol (E2; 2.0 microg/rat) followed by 1.0 mg/rat of P, and (3) EB alone (5.0 microg/rat) for 6 days. No differences in sexual receptivity or in paced mating behavior were observed across doses of P (1.0-8.0 mg/kg). In contrast, the number of hops and darts per min increased with the dose of P administered. E2 + P administration resulted in slightly, but significantly, lower levels of sexual receptivity along with significantly longer contact-return latencies following an intromission in relation to the other treatment conditions. In addition, female rats exhibited fewer hops and darts per min in response to E2 + P than in response to EB + 8.0 mg/kg of P. The administration of EB alone for 6 days induced levels of receptivity and paced mating behavior indistinguishable from EB + P, while eliciting significantly fewer hops and darts per min than the EB + 8.0 mg/kg P treatment condition. Hormone priming regimen had no effect on the percentage of exits displayed during the paced mating tests in any experimental phase. Dose of P had no effect on paced mating behavior in sexually receptive rats. In addition, P does not appear to be necessary for the display of paced mating behavior following long-term treatment with EB. In contrast, the pulsatile administration of E2 + P induced a different pattern of paced mating behavior in sexually receptive rats.

Animals↗

PubMed1975

Relative mating activity of the sexes in homokaryotypes of Drosophila persimilis from a Redwoods population.

Previous tests for mating activity of Drosophila persimilis homokaryotype KL (Klamath) and MD (Mendocino) chromosomal arrangements (northern California population: Redwoods) had shown KL to mate faster on the average than MD in homogamic tests. A strain (double-cross hybrid of four KL lines from the same population) with reliable high mating activity was developed for testing the sexes separately. Five pairs of KL-MD homokaryotype strains were chosen to be tested by the criterion that each pair had been derived from a separate wild KL/MD progenitor. Strains were crossed within arrangements in a diallelic design (20 inter- and five intrastrain crosses tested in 16 replicates per cross) to provide mating activity indices of four sets: KL females, KL males, MD females, MD males. Mating tests employed ten virgin experimental flies with ten tester (double-cross hybrid) flies of the opposite sex in 30-min observation periods. All flies were matured for 5 days at 25 degrees C before testing. Among parental strains, females were consistently higher in mating activity than males for both KL and MD arrangements. Most interstrain hybrids were heterotic, with KL and MD females not significantly different. However, hybrid MD males displayed greatest variation and had lowest mating activity, while KL males were the least variable and highest in mating activity. With heterosis in the hybrids, there was no predictability (additivity) from performance of parental strains to hybrid offspring. Mating activities of the two sexes were uncorrelated, indicating either that the sexes have independent genetic systems controlling mating activity or that the expression of the same genetic system is influenced by sex. Since the hybrid males of the two karyotypes displayed different courtship activity while the females were at about an equal level of receptivity, intrasexual selection among males is likely to be important in nature.

Alleles↗

PubMed1989

Reproductive performance of three fat-tailed breeds of sheep mated to native, Corriedale and Targhee rams.

Reproduction and lamb production of three fat-tailed, carpet-wool Iranian breeds of sheep; Karakul (130 ewes), Mehraban (103) and Baluchi (119) were studied. The ewes were mated either as purebreds or with Corriedale or Targhee rams. The overall least-squares means for ewes mated (showed oestrus) or ewes exposed, ewes lambed or ewes mated, lambs born of ewes lambing (prolificacy), lambs born alive of total lambs born, lambs weaned of live lambs born, lambs weaned (75 days of age) of ewes mated, kg lamb weaned per ewe mated and kg lamb weaned per 100 kg ewe mated were 98.3%, 93.5%, 103.1%, 94.9%, 97.8%, 90.0%, 18.2 kg and 38.4 kg respectively. The native breeds were not different for any of the traits studied except for prolificacy which was higher in Mehraban than in Karakul. Purebred matings did not differ from the crossbred matings for any of the traits concerning the number of lambs but crossbreeding improved kg lamb weaned per ewe mated (9.2%, P = 0.08) and kg lamb weaned per 100 kg ewe mated (10.0%, P less than 0.05). Among the three native breeds Karakul showed the largest improvement when crossed with the exotic rams for the traits concerning kg lambs weaned. Corriedale and Targhee rams had similar effects on all the traits studied. A lower percentage of virgin ewes showed oestrus, had a lower twinning rate and productivity compared with the mature ones. Sex was not a significant source of variation in lamb livability.

Age Factors↗

PubMed1982

Influence of single-sire and multiple-sire natural mating on pregnancy rate of beef heifers.

Twelve mature Angus bulls possessing similar semen quality were used to study the effects of single and multiple services and single-sire and multiple-sire mating on pregnancy rate of beef heifers. Heifers were observed for natural estrus twice daily and mated within 6 hr of onset of estrus. Pregnancy rate was determined by rectal palpation at 60 days post-mating. Pregnancy rate of heifers receiving one service per estrus averaged 62.1% (n=124) and pregnancy rate of heifers receiving multiple services (single-sire) per estrus averaged 62.9% (n=105). Pregnancy rate per estrus of heifers mated to three sires (multiple-sire, one service per sire; 74.0%, n=123) was significantly higher than that of heifers mated to a single sire (62.9%). The range in pregnancy rate per bull for single-sire matings was large (0 to 95%), but this range was reduced among the same bulls used for multiple-sire matings (68 to 84%). These results indicate that pregnancy rate to one service did not differ (P>.10) from pregnancy rate to multiple services among single-sire matings, but multiple-sire matings increased (P<.05) pregnancy rate per estrus by 11% over that obtained with single-sire matings.

Journal Article↗

PubMed1991

Effects of food and mates on time budget in Aplysia fasciata: integration of feeding, reproduction, and locomotion.

This study examines the time budgeted to different behaviors in Aplysia fasciata under three conditions: (1) animals have constant access to food and mates: (2) there is access to food, but not to mates; (3) neither food nor mates are present. The data suggest a number of rules underlying behavioral integration: (1) Feeding, reproductive behaviors, and activity seem to be natural categories for behavioral choice. Feeding and reproductive behaviors are controlled in tandem by a common arousal mechanism, while time left over after animals feed and reproduce is distributed in a fixed ratio between locomotion (crawling and swimming) and inactivity (immobility and movement in place). (2) Relative distribution between different forms of locomotion and inactivity is modified by changes in motivational state. More time is spent swimming than crawling when feeding and/or mating is prevented, while more time is spent moving in place than immobile when the arousal level is increased. (3) Feedback control of feeding and reproduction is asymmetric. Satiation of feeding inhibits the common arousal. In the absence of food, time spent on reproductive behaviors increases due to disinhibition of the common arousal. By contrast, positive feedback arising from sexual behavior excites the common arousal. When mating is prevented by removing potential mates, time spent feeding decreases. (4) Generally, animals choose between performing the three main categories of behavior. Although Aplysia simultaneously can feed and mate, or locomote and mate, they do so infrequently. By contrast, different types of reproductive behaviors (male mating, female mating, egg-laying) are commonly performed simultaneously.

Animals↗

PubMed1996

Effects of paced and non-paced mating stimulation on plasma progesterone, 3 alpha-diol and corticosterone.

In the female rat, gonadal and adrenal progestins and androgens modulate sexual receptivity and in turn, their levels increase in response to mating stimulation. Paced mating, in which the female controls the timing of sexual contacts with the male, is particularly effective at eliciting acute increases in progesterone (P) and 5 alpha-Androstane-3 alpha, 17 beta-diol (3 alpha-Diol). Interestingly, restraint stress produces comparable increases in P and 3 alpha-Diol levels, as well as increases in corticosterone (CORT) levels. In this study, we explored the possibility that paced mating would be associated with increased CORT, in conjunction with mating-induced increases in P and 3 alpha-Diol. Ovariectomized rats primed with estradiol benzoate (10 micrograms in oil SC) and P (0.5 mg in oil s.c.) received a single ejaculatory series from males in paced or non-paced mating tests. Fifteen minutes post-mating rats were exposed to CO2 and rapidly decapitated for the collection of trunk blood and determination of P, 3 alpha-Diol and CORT via radioimmunoassay. As expected, P and 3 alpha-Diol concentrations were significantly elevated in serum obtained from animals allowed to pace their sexual contacts with males compared to those which did not pace their contacts. Importantly, although all mated animals had CORT levels between 10-20 micrograms/dl, there were no differences between paced and non-paced conditions. This suggests that the acute rises in P and 3 alpha-Diol in response to paced mating are not due to paced mating being more stressful than non-paced mating.

Androstane-3,17-diol↗

PubMed2004

The effect of ventral nerve cord severance and male castration on female mating behavior, clutch size, and maternal care in the ring-legged earwig.

Mating is critical for the expression of oviposition and maternal care in the earwig, Euborellia annulipes; additionally, mating diminishes receptivity to additional mating and promotes a decline in juvenile hormone synthesis at the end of the gonadotrophic cycle (in contrast to most insect species wherein mating stimulates juvenile hormone production). We report here that severance of the ventral nerve cord of virgin females similarly promoted egg deposition and maternal care of eggs, diminished mating receptivity, and elicited a timely decline in juvenile hormone biosynthesis. Mating of intact females to adult males that were castrated as larvae did not abolish oviposition; however, clutch size was reduced, and no eggs developed. Such castrated males had smaller seminal vesicles than did intact males, presumably attributable to lack of sperm in castrated males. In contrast, mating of intact females to males castrated on day 1 of adult life did not reduce clutch size compared with those of sham-operated animals and did not abolish fertilization; in fact, these castrated males produced viable offspring after six matings. These results are consistent with the notion that ventral nerve cord severance mimicked mating in intact animals. Following mating, the ventral nerve cord likely is a conduit to release the brain from inhibiting oviposition and maternal care. The presence of sperm in the spermatheca is not necessary for release of this inhibition but may modulate clutch size.

Animals↗

PubMed2002

Mating-activated nitric oxide-producing neurons in specific brain regions in the female rat.

Nitric oxide (NO)-containing neurons have been localized in various parts of the central nervous system including the hypothalamus. NO plays an important role in the regulation of reproductive activities including sexual behavior and pituitary hormone secretion. To test the hypothesis that NO-containing neurons in specific brain areas may respond to the stimulus of mating and participate in integrating the tactile information in the hypothalamus, this study used Fos as a marker of neuronal activity. Proestrous rats receiving intromissions (mated group) from males or mounts-without-intromission (mounted group) were sacrificed along with rats taken directly from their home cage (control group) 90 min after the beginning of mating or mounting. NOergic neurons were labeled by histochemical reaction for nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d). The presence of activated NO-producing (double-stained NADPH-d/Fos) neurons was quantitatively assessed in several brain areas before and after mating. The results showed that mating-with-intromissions induced a significant increase in the percentage of NADPH-d/Fos colabeled neurons in the medial preoptic area (mPOA) and the magnocellular component of the paraventricular nucleus (PVNm) compared to mounts-without-intromission or control treatment. Both mating and mounting induced Fos expression in NADPH-d-positive cells in the ventromedial nucleus of hypothalamus (VMN). In contrast, the expression of Fos in the NADPH-d-positive neurons in the supraoptic nucleus (SON) and the parvocellular portion of the paraventricular nucleus (PVNp) was not influenced by either mating or mounting although abundant NO-containing neurons were found in the two brain areas. The second experiment of the study examined whether NOergic neurons in these brain areas are influenced directly by estrogen by determining the number of NADPH-d-positive neurons that contained the estrogen receptor alpha (ERalpha), the classical ER. Double labeled NADPH-d/ERalpha neurons were observed in several brain areas including the mPOA and VMN while few, if any, NADPH-d-positive neurons in the SON, PVNm or PVNp contained ERalpha. The results suggest that the activated NOergic neurons in these brain areas may be involved in processing and integrating the mating stimulus. Further investigation is required to determine the physiological role of the mating-activated NOergic activity in specific mating-induced changes in reproductive neuroendocrinology.

Animals↗

PubMed2000

Regulation of pheromone inhibition in mated females of Choristoneura fumiferana and C. rosaceana.

In the spruce budworm, Choristoneura fumiferana, and the obliquebanded leafroller, C. rosaceana, mating significantly depressed pheromone production after 24 h. On subsequent days, the pheromone titre increased slightly in C. fumiferana, but not in C. rosaceana. No pheromonostatic activity was associated with male accessory sex gland (ASG) extracts, 20-hydroxy-ecdysone or hemolymph taken from mated females. However, pheromone production in mated females was not suppressed when the ventral nerve cord (VNC) was transected prior to mating, indicating that an intact VNC is required to permanently switch off pheromone production after mating. As suggested for other moth species, the presence of sperm in the spermatheca probably triggers the release of a signal, via the VNC, to inhibit pheromone production. The fact that in both species the brain-suboesophageal ganglion (Br-SEG) of mated females contains pheromonotropic activity and that their pheromone glands may be stimulated by the synthetic pheromone-biosynthesis-activating-neuropeptide (PBAN) or a brain extract supports the hypothesis that the neural signal prevents the release of PBAN into the hemolymph rather than inhibiting its biosynthesis. Therefore, we speculate that following the depletion of sperm in the spermatheca, the neural signal declines and is less effective in preventing the release of PBAN, thereby stimulating the resumption of pheromone production, as seen in mated C. fumiferana females. In a previous study, mating was shown to induce a significant rise in the juvenile hormone (JH) titre of both Choristoneura female moths, suggesting that post-mating pheromone inhibition may be under hormonal regulation. However, following topical applications or injections of the juvenile hormone analogue (JHA) and JH II into virgins, the pheromone only declined significantly 48 h after treatment in C. rosaceana. This suggests that the significant rise in the hemolymph JH titre after mating in C. rosaceana females plays a role in keeping the pheromone titre consistently low throughout their reproductive life. These findings will be discussed in relation to the different life histories of the two Choristoneura species.

Journal Article↗

PubMed1999

Assessment of sows mating efficacy during the low productive period after early weaning: a field study.

Data on sows bred after weaning (n = 9,540) and their lactation feed intake records (average lactation length <20 d) were obtained from 16 commercial farms. Weaning-to-first-mating intervals (WMI) at 6 to 12 d and 0 to 6 d after weaning were defined as the low and high productive periods, respectively. Of the 9,192 sows mated, 80.5 and 19.5% were mated at 0 to 6 d and 7 to 12 d, respectively. In logistic regression analysis, lower parity, shorter lactation length, lower average daily feed intake (ADFI) during lactation, and a greater number of weaned pigs were associated with mating at 7 to 12 d after weaning (P < or = 0.045). Exponentiating the coefficients in logistic regression analysis, the odds ratios were 0.79 for parity, 0.84 for ADFI during lactation, 0.85 for lactation length, and 1.05 for weaned pigs, respectively. A sow with a 14-d lactation length is 2.3 (1/0.85(5)) times as likely to mate within a 6- to 12-d WMI as a sow with a 19-d lactation length. Thus, the early weaned sows are more likely to mate during the low productive period than the later weaned sows. The odds for party 0.79 imply that Parity 1 sows were 1.6 (1/0.79(2)) times as likely to mate within a WMI 6 to 12 d as Parity 3 sows. For each 1-kg increase in ADFI, a mating occurrence during the low productive period decreased by 0.84 times. Sows are mated during the low productive period because this period is a part of the distribution of WMI in a herd. However, our research suggests that increasing feed intake during lactation and maintaining parity proportion appropriate to the herd can decrease the proportion of sows mated during the low productivity period.

Animals↗

PubMed2000

Factors influencing age at first mating in purebred Swedish Landrace and Swedish Yorkshire gilts.

The aim of the present study was to retrospectively analyze causes of the variation in age at first mating in Swedish Landrace (L) and Swedish Yorkshire (Y) gilts. Production traits including growth rate from birth to 100kg body weight and backfat thickness at 100kg body weight were also studied. Data analyzed were obtained from 11 L and 11 Y nucleus herds and included gilts born during a 5-year-period from October 1993 until September 1998. The complete data set included information on 14,761 gilts (6997 L and 7764 Y). Traits analyzed included age of gilt at first mating, growth rate and backfat thickness. Seven statistical models were used for analyzing the data. Factors included were gilt breed, birth month, parity number and size of the litter in which the gilt was born as well as their interactions. Compared with Y gilts, L gilts grew faster (571 versus 556 g/day; P<0.001), had a thinner backfat (11.9 versus 12. 3mm; P<0.001) at 100kg body weight and were 12 days younger at first mating (237 versus 249 days; P<0.001). Birth month significantly (P<0.001) influenced age at first mating, growth rate and backfat thickness. Gilts born from smaller litters were mated at younger age than gilts born from larger litters even when age at first mating was adjusted for the effect of growth rate and backfat thickness. Growth rate of the gilts decreased when 'birth litter size' increased. Gilts born from primiparous sows grew slower, had a thinner backfat at 100kg body weight and were older at first mating compared with gilts born from multiparous sows. Gilts with a higher growth rate were younger at first mating than those with a lower growth rate. Gilts with a thicker backfat at 100kg body weight were mated earlier than the thin ones. However, the effect of growth rate on age at first mating was more pronounced in the gilts with a thinner backfat rather than the ones with a thicker backfat.

Age Factors↗

PubMedDate not supplied

Effects of advanced maternal age on development of preimplantation mouse embryos obtained from delayed mating.

Rodent embryos resulting from delayed mating grow more quickly than those resulting from normal mating. To clarify the effects of maternal age on this enhanced growth and rapid differentiation of mouse embryos obtained from delayed mating, we studied normal (0 h after ovulation) and delayed mating (6 h after ovulation) subgroups in two different age groups (middle-aged, 9-11 months; elderly, 13-15 months), and compared the number of cells and the proportion of blastocyst formed (morphologically advanced blastocysts) among them. In middle-aged female mice, preimplantation embryos derived from delayed mating progressed more rapidly than their normally mated counterparts. The number of cells and the proportion of blastocyst formed among embryos from delayed mating were almost 3 h ahead of those of normal embryos. In the delayed mating subgroup from elderly mice, an enhanced rate of development was not observed. There was no difference in development of normally mated embryos from middle-aged females compared to each counterpart from elderly female mice. Preimplantation mouse embryonic development from delayed mating may be affected by advanced maternal age.

Animals↗

PubMed1998

Sib mating designs for mapping quantitative trait loci.

The power to separate the variance of a quantitative trait locus (QTL) from the polygenic variance is determined by the variability of genes identical by descent (IBD) at the QTL. This variability may increase with inbreeding. Selfing, the most extreme form of inbreeding, increases the variability of the IBD value shared by siblings, and thus has a higher efficiency for QTL mapping than random mating. In self-incompatible organisms, sib mating is the closest form of inbreeding. Similar to selfing, sib mating may also increase the power of QTL detection relative to random mating. In this study, we develop an IBD-based method under sib mating designs for QTL mapping. The efficiency of sib mating is then compared with random mating. Monte Carlo simulations show that sib mating designs notably increase the power for QTL detection. When power is intermediate, the power to detect a QTL using full-sib mating is, on average, 7% higher than under random mating. In addition, the IBD-based method proposed in this paper can be used to combine data from multiple families. As a result, the estimated QTL parameters can be applied to a wide statistical inference space relating to the entire reference population.

Animals↗

PubMed1996

Strategic self-promotion and competitor derogation: sex and context effects on the perceived effectiveness of mate attraction tactics.

In this article, 7 evolutionary hypotheses about the context-specific nature of mate attraction effectiveness were empirically tested and supported. In the context of short-term mating, for example, men have faced the adaptive problem of finding sexually accessible women. As a result, men express a preference for sexually availability in short-term mates. In Studies 1 and 2, separate groups of undergraduate participants judged sexual availability tactics as most effective when used by women seeking short-term mates, confirming the hypothesized link between the judged effectiveness of mate attraction tactics used by one sex and the expressed mate preferences of the other. Showing resource potential was judged most effective for men seeking a long-term mate, whereas giving resources immediately was judged most effective for men seeking short-term mates, confirming the hypothesized importance of temporal context in mate attraction effectiveness. Discussion focuses on the context-specificity of human mating psychology and on linking evolutionary and traditional approaches to romantic attraction.

Adult↗

PubMed1997

From vigilance to violence: mate retention tactics in married couples.

Although much research has explored the adaptive problems of mate selection and mate attraction, little research has investigated the adaptive problem of mate retention. We tested several evolutionary psychological hypotheses about the determinants of mate retention in 214 married people. We assessed the usage of 19 mate retention tactics ranging from vigilance to violence. Key hypothesized findings include the following: Men's, but not women's, mate retention positively covaried with partner's youth and physical attractiveness. Women's, but not men's, mate retention positively covaried with partner's income and status striving. Men's mate retention positively covaried with perceived probability of partner's infidelity. Men, more than women, reported using resource display, submission and debasement, and intrasexual threats to retain their mates. Women, more than men, reported using appearance enhancement and verbal signals of possession. Discussion includes an evolutionary psychological analysis of mate retention in married couples.

Adolescent↗

PubMed2000

Epidemic obesity: are genetic factors involved via increased rates of assortative mating?

OBJECTIVE: Prevalence rates of obesity have been increasing in several countries over the past two decades. Mainly secular changes in energy intake and expenditure have been invoked to underly the increasing rates; genetic factors have not been considered because of the very recency of this phenomenon. We hypothesize that genetic factors might very well be involved via an increased rate of assortative mating between obese individuals. We speculate that the recent upsurge in social stigmatization of obese individuals underlies the hypothesized increase in assortative mating. DESIGN: To accumulate evidence for our hypothesis we analysed deduced rates of assortative mating among parents of extremely obese children and adolescents, who belonged to two different large study groups (n = 201 and n = 270). For this purpose we calculated parental body mass indices (BMIs) based on (a) measured current heights and weights, (b) self-reported current heights and weights, and finally (c) measured current heights and recalled weights at ages 20 and 30, respectively. BMI centiles were determined which in turn were attributed to the respective BMI decile. Deduced rates of assortative mating were evaluated in bivariate histograms of the paternal and maternal BMI deciles. RESULTS: High rates of assortative mating were observed as deduced from the bivariate histograms, which revealed a fairly consistent pattern. Thus, in the first study group almost 35% of the parental pairs had a BMI in the tenth decile; over 50% of the mothers and fathers had a BMI in this top decile. Recalled parental BMIs at ages 20 and 30 also clustered in the upper decile. These results were basically replicated in the second study group. In addition, parental loading on the tenth decile was shown to be higher for the subgroup of children and adolescents who had a BMI equal to or exceeding the highest BMI of the population-based age and gender matched control group. CONCLUSIONS: Our results indicate that assortative mating is common among parents of extremely obese children and adolescents, ascertained between 1995 and 1997. In addition, the parental loading on the tenth decile is most prominent for the most obese children. Whereas we are unable to document an increased rate of assortative mating, we interpret our results as being consistent with the hypothesis that an increased rate of assortative mating has contributed to the recent rise in obesity rates in several countries. Thus, assortative mating warrants further studies to assess its impact on obesity prevalence rates through both genetic and non-genetic mechanisms. Our results suggest that assortative mating might especially increase the rates for extreme obesity.

Adolescent↗

PubMed1999

Effects of pre- and post-mating nutritional status on hepatic function, progesterone concentration, uterine protein secretion and embryo survival in Meishan pigs.

This experiment examined whether the pre- or the post-mating diet had greater impact on embryo survival in Meishan gilts. Gilts received either a maintenance (1.15 kg day(-1); n = 12) or a high (3.5 kg day(-1); n = 12) diet during the oestrous cycle preceding mating. After mating, half the animals in each group received either the maintenance or the high diet until slaughter on Day 12. Gilts fed the high pre-mating diet had more corpora lutea (22.7 v. 19.0, SED = 0.98; P<0.001), increased embryo survival (95.5% v. 74.8%, SED = 7.58; P<0.01) and heavier corpora lutea (-0.71 log g v. -0.90 log g, SED = 0.09; P = 0.07) compared with gilts fed the maintenance diet prior to mating. The post-mating diet had no effect on embryo survival. There were no treatment effects on blastocyst developmental stage, luteal surface area or progesterone release. Gilts receiving the high post-mating diet had heavier livers than those fed the maintenance post-mating diet (1.45 v 1.08% of total bodyweight, SED = 0.07; P<0.001), suggesting that these gilts have a greater capacity to metabolize progesterone. Pre-mating nutritional status therefore appears to be a greater determinant of embryo numbers and survival than the post-mating diet.

Acid Phosphatase↗

PubMed1980

Mutations preventing transpositions of yeast mating type alleles.

Homothallic strains of Saccharomyces cerevisiae can switch from one mating type to the other as often as every cell division. The conversion of mating type alleles (from MATa to MATalpha or vice versa) depends on other, unexpressed copies of a or alpha information that can be transposed to MAT. Previously, "inconvertible" mutations within MATalpha and MATa have been described that block the excision of the MAT allele. In this paper we describe two cis-acting mutations that also impair mating type switching and lie very near, but outside, the MAT locus. Both "stuck" mutations, stk1 and stk2, diminish the efficiency of converting MATa to MATalpha to less than 10% of normal. The stk1 mutation also slightly reduces conversion of MATalpha to MATa, whereas stk2 has no discernible effect. Unlike the inconvertible MATalpha-inc and MATa-inc mutations within MAT, the stk mutations are not replaced by wild-type sequences after the "stuck" cells occasionally switch to the opposite mating type. Because these mutations are not "healed" by mating type conversions, they must lie in sequences outside of the transposable mating type information. These results indicate that the efficient replacement of MAT alleles depends on sequences both within and adjacent to the MAT locus. Among subclones of homothallic stk MATa strains, approximately 2% show "illegal" transpositions of mating type genes. In these colonies the silent copy of alpha information at the HMLalpha locus has been converted to a, without any change of MATa or the silent a copy at HMRa. Such conversions of the unexpressed library genes are not found in wild-type homothallic strains that can switch mating type efficiently, but they are found in MATa-inc and MATalpha-inc strains. It appears that all of the cis-acting mutations within or adjacent to mating type result in these unusual switches of mating type information at HML and HMR.

Alleles↗