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PubMed2005

Olfactory conditioned partner preference in the female rat.

Paced copulation induces conditioned place preference in female rats. The authors examined whether associating almond-scented males with paced copulation induces conditioned partner preference. The paired group received 4 paced copulations with almond-scented males and 4 nonpaced copulations with unscented males sequentially at 4-day intervals. The unpaired group received the opposite order of association, whereas the randomly paired group received random associations. A 4th group received a single pairing. On the final test, females were placed into an open field with 2 males, 1 scented and 1 unscented. Females in the paired group solicited the scented male more frequently, and most chose the scented male for their 1st ejaculation. Thus, an odor paired with paced copulation elicits conditioned partner preference in female rats.

Analysis of Variance↗
PubMed2002

Fertility of male and female emus (Dromaius novaehollandiae) as determined by spermatozoa trapped in eggs.

Changes in the fertility status of 10 pairs of emus were investigated using egg break-out and numbers of sperm in the perivitelline membrane of the germinal disc (GD) region. After the sexes were separated, sperm in consecutive eggs declined approximately logarithmically at a mean (+/-SEM, n = 10 females) rate of -0.148 +/- 0.021 per log day. Sperm continued to be detected in eggs for 16.5 +/- 1.7 days during which 5.6 +/- 0.6 fertilized eggs were laid. Fertilized eggs that did not contain detectable sperm were laid by five females for a further 2.2 +/- 0.9 days. Based on break-out fertility, the fertile period continued for up to 18.7 +/- 2.1 days, for which the mean number of laid eggs was 6.3 +/- 0.8. An egg with a 50:50 chance of being fertilized would contain 3.5 sperm mm(-2) of GD. Based on the sperm decline model, an egg containing that many sperm would be laid 21 days after the last copulation. In emus that were not separated and allowed to incubate their eggs (n = 3 pairs), the number of sperm in eggs laid before and during incubation declined in a manner similar to that after the last copulation and egg-laying stopped after the females had laid 3.3 +/- 0.3 eggs. After incubation was terminated, females resumed laying within 8.3 +/- 1.2 days and the number of sperm in eggs gradually increased but it did not return to pre-incubation levels. In non-incubating emus (three pairs), the number of sperm in eggs declined as laying progressed, although lit was higher during the period when the first seven eggs were laid than during the period when the rest of eggs were laid (214 +/- 39 v.100 +/- 16 sperm mm(-2) of GD). Sperm numbers varied between successive eggs but a sharp increase followed by a decrease acted as an indicator of recent copulation. There were 8.7 +/- 0.3 such increases per laying period (one per 2.8 +/- 0.2 eggs), a frequency that suggests that emus copulate once weekly. In conclusion, as long as a female emu is supplied with sperm on a weekly basis, she will be fertile but, when copulations stop, she will stop laying soon after. Male fertility appears to fall towards the end of the laying season and it can be affected by egg incubation at any time of the season.

Animals↗
PubMedDate not supplied

Ejaculatory process and related semen characteristics.

South American camelids are dribble ejaculators, and urethral contractions occur throughout copulation, which may last 25 min. The urethral contractions and their association with semen characteristics during copulation were determined in llamas and alpacas. A transrectal probe was held in the rectum of the male while copulating an artificial vagina, which was accessed underneath the dummy through a hole. The semen-collecting tube was changed every 5 min. Semen characteristics, color, volume, consistency, motility, concentration, and percentage of live sperm were determined at 5-min intervals. Urethral contractions were evenly distributed during copulation: 40 in alpacas and 63 in llamas (p < .05), with a general range of 11 to 132. Semen color was milky in 63%, and translucent in 36.5% for alpacas; and creamy (9.9%), milky (47%), and translucent (42%) for llamas. The mean volume of ejaculate was 0.3, 0.4, 0.6, 0.7, 0.6, 0.8, 0.3, and 3.0 mL for 5, 10, 15, 20, 25, and 30 min, respectively. Semen consistency was variable: viscous (65%) and semiviscous (34%) in alpacas; and viscous (57%) and semiviscous (42%) in llamas. Spermatic motility varied between 60 and 80% for the llama, and 40 and 80% for the alpaca. Spermatic concentration varied between 60 and 188 x 10(3)/mm3 in llamas, and 30 and 170 x 10(3)/mm3 in alpacas. Percentage of live sperm varied the least: 81 to 90% in llamas and 65 to 90% in alpacas. The ejaculate of llamas and alpacas is not fractionated, urethral contractions are evenly distributed, during copulation, and semen characteristics are present throughout the copulatory period.

Animals↗
PubMed2003

A matter of taste: direct detection of female mating status in the bedbug.

Males of the bedbug, Cimex lectularius, traumatically inseminate females by inserting a needle-like intromittent organ (penis) through the female's abdominal wall after she has fed. We demonstrate that: (i) mating duration determines ejaculate size; (ii) a female's first copulation in a bout of copulations always lasts longer than subsequent copulations; (iii) the intromittent organ bears sensillae; (iv) males use their intromittent organ to 'taste' whether their current mate has recently copulated; and (v) the consequence of detecting female mating status is the reduction of copulation duration and ejaculate size. We discuss why male bedbugs might show this pattern of ejaculate-size adjustment.

Animals↗
PubMed1982

Reproductive behavior in Varecia variegata.

Testicle size during the breeding season is related to age and previous social environment of the male. The size of testicles in adult males exceeds that of young males. Adult males' testicles are much larger than the testicles of young males; enlargement starts 2-3 months prior to the breeding season, peaking around copulation day. Subadult males (3-year-olds) are able to develop full-sized testicles and sire offspring, but did so only when housed with adult females and not with their family group. Although females may reach sexual maturity in their second breeding season after birth, they do not necessarily breed successfully. Vaginal estrus lasts considerably longer (2-3 days) than behavioral estrus (6-12 h). Different stages of vaginal estrus can visually be determined by the development of the vaginal region (swelling; appearance of pink point; long, pink slash; opening to round pink circle, and in the latter stage, by smears, confirming the different physiological stages, proestrus, estrus, metestrus). Behavioral estrus appears in the last hours of vaginal estrus. Captive adult females show increasingly hostile behavior to their maturing daughters. These have to be removed from the group when they are sexually mature. The same degree of hostility can be found between fathers and subadult sons during the breeding season. Dominant males show a typical 'guarding behavior' over the entire period of behavioral estrus of the female. They remain close to the female, vigorously preventing other males from approaching or mating with the female. At the beginning and the end of copulations, the female shows a sequence of aggressive behaviors towards the dominant male. Successful copulations can be determined by their duration (1-2 min), and a head-twisting movement of the male during ejaculation. Normally 16-25 copulations occur on copulation day, usually all with the same partners. The average gestation length is 102.5 days. Adult females normally give multiple births, whereas primiparous females tend to have single infants.

Age Factors↗
PubMed1987

Sperm-epithelium relationships in relation to the time of insemination in little brown bats (Myotis lucifugus).

Copulation lasted for up to 46 min in little brown bats. Spermatozoa were stored in both the uterus and the utero-tubal junction, although intimate relationships between spermatozoa and the epithelium were particularly evident in the utero-tubal junction, and were established at the beginning of the period of sperm storage. Polymorphonuclear leucocytes were present in all uteri irrespective of whether or not they had been inseminated but were not generally present in the utero-tubal junction or oviduct. Engulfment of spermatozoa by the epithelial cells of the utero-tubal junction and by polymorphonuclear leucocytes in the uterine glands was evident soon after copulation. It is suggested that this may effect the removal of defective spermatozoa and allow luminal spermatozoa access to the spatially restricted storage sites. Uninseminated female bats attempted to elicit copulation from torpid males, and were also observed adjacent to copulating pairs. Female bats also uttered copulation calls.

Animals↗
PubMed1985

The induction of ribosome biosynthesis in a nonmitotic secretory tissue.

Many investigations of the biosynthesis of ribosomes have revealed that ribosome numbers increase with growth rate in a parallel fashion. However, we have now shown that there is also a need for active ribosome synthesis in a nonmitotic tissue which is induced to secrete. The paragonial glands of Drosophila melanogaster produce and secrete proteins that are found in the seminal fluid. Following even a single copulation event these glands are substantially reduced in size, but rapidly refill, synthesizing new secretion proteins (Chen, P.S. 1980) in Invertebrate Systems in Vitro (Kurstak, E., Maramorosch, K., and Dubendorfer, A., eds) pp. 303-313, Elsevier, Amsterdam) Anticipating that paragonial gland cells might require more ribosomes to accomplish this burst of protein synthesis, we injected 10-day-old adult male flies with either [32P] phosphate or [35S]methionine, allowed them to copulate (40 +/- 20 min after injection), and then measured the amounts of rRNA and ribosomal protein synthesis taking place with time. There is clearly a burst of ribosome synthesis starting as early as 30 min after copulation and declining after 6 h. This is evidenced by the coordinate accumulation of labeled rRNAs and ribosomal proteins. However, further experiments showed that there is no concomitant rise in the accumulation of ribosomal protein mRNAs. This suggests that these mRNAs are underutilized in the paragonial glands before copulation and more actively translated after copulation. A stimulation of translation of ribosomal proteins is then well-coordinated with increased rRNA transcription, but an increase of ribosomal protein mRNAs is not coordinated with these events. Both the up- and down-regulation of ribosome biosynthesis need not be coupled to cell growth or a specific developmental schedule, but rather may be due to the need for secretory protein synthesis.

Animals↗
PubMed1981

On the presence of prostatic secretion protein in rat seminal fluid.

The copulating plug collected from the tip of the penis from rats immediately after decapitation contains a protein very similar and probably identical to PSP (prostatic secretion protein); this protein has earlier been purified from rat prostatic cytosol and characterized. The protein present in the copulating plug interacts with [3H]estramustine and binds to the antibody raised against rat PSP. The concentration of the protein in the copulating plug is 400 ng/mg of total protein, when measured using the radioimmunoassay technique developed earlier for measurement of PSP in rat prostate. The [3H]estramustine-protein complex formed in a preparation of the copulating plug has an apparent molecular weight of about 50,000 and a sedimentation coefficient of about 3S when analyzed using sucrose density gradient centrifugation. The complex was retained on Concanavalin-A Sepharose indicating that the protein is a glycoprotein. Binding of the complex was also observed on hydroxylapatite and DEAE-Sephadex columns, from which it was eluted at 0.18 M KCl. Light microscope autoradiograms of rat sperms incubated with 125I-labeled PSP indicated that PSP is bound to all parts of the sperms. A macromolecule interacting with the PSP-antibodies is also present in human seminal fluid but at a concentration considerably lower than in rat seminal fluid. The present study shows that a macromolecule probably identical to prostatic secretion protein is present in the copulating plug from the rat. The biological role of this protein in normal male fertility is discussed.

Animals↗
PubMed1999

Yelling for sex: harem males compete for female access in bronze-winged jacanas.

Sperm competition in sex-role reversed, polyandrous jacanas is intense because females copulate with multiple male mates before laying each clutch. These males may be unable to attempt to maximize their share of copulations by mate guarding or forcing copulations. Instead, males in polyandrous harems may compete for sexual access to the female by giving a call, termed the 'yell', to attract her. Male bronze-winged jacanas, Metopidius indicus, yelled at higher rates in larger harems, and when the female was further from the yeller or on a comate's territory. Half of all yells were given at mating platforms where all copulations occurred. Males that received the clutch yelled at lower rates during the incubation and chick care periods. Yells attracted the female when she was far from the yeller or with a comate. When the yell of a polyandrous male was broadcast from his territory, the female was more likely to fly to his territory during playback than during control periods. Within polyandrous harems the males that yelled at the highest rates received the most copulations, and three out of four females gave clutches to the male that gave the longest and most frequent yells, so females may have used yells to assess male quality. Intrusions by females, but not males, increased during yell playbacks, and tended to be more frequent on the territories of males with high yell rates. Females may therefore respond to their mates' yells because yells may attract female intruders which may attempt to take over the territory. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1999

Sperm transfer and male competition in a bumblebee.

We investigated the dynamics of sperm transfer and the potential conflict between sexes over mating opportunities in the bumblebee, Bombus terrestris L. We recorded copulation duration in flight cages and manipulated copulation time by separating mating pairs. Sperm transfer and filling of the spermatheca were measured by dissecting queens at different time intervals after the onset of mating. On average, copulations lasted 37 min but most sperm were transferred into the female genital tract within the first 2 min. Sperm reached the spermatheca after 30-80 min. Males transferred a sticky gelatinous product of their accessory glands, the 'mating plug', to the female within 10-30 min of the onset of copulation. Hence the duration of the copulation matched the time required to deposit the plug fully. A likely function of the plug is to prevent backflow of sperm, but by artificially transferring mating plugs we showed that the plug also decreased sperm transfer into the female's spermatheca for at least 4 h and possibly for much longer (8 h or more). Increased mating costs arising from male selfishness may prevent females from seeking further matings. This may help to explain why females of B. terrestris seem to be mostly singly mated in the field, even though, in experiments with artificially inseminated queens, higher sperm diversity increases reproductive output. This is the first report of a mating plug for the Bombini but similar devices are known from two other tribes of the Apidae, the Apini and Meliponini. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed2000

Female-mediated differential sperm storage in a fly with complex spermathecae, Scatophaga stercoraria.

Multiple spermathecae potentially allow selective sperm use, provided that sperm from rival males are stored differentially, that is, in different proportions across storage compartments. In the yellow dung fly, Scatophaga stercoraria, females have three spermathecae arranged as a doublet and singlet. To test whether females store the sperm of rival males actively and differentially, we mated fixed male pairs to three females. After copulation, females were (1) dissected immediately before they could start laying a clutch of eggs, (2) left awake for 30 min but prevented from oviposition, or (3) anaesthetized with carbon dioxide for 30 min to interfere with the muscular control presumably required for sperm transport from the site of insemination to the spermathecae. For each female, we estimated the proportion of the second male's sperm stored in her spermathecae (S(2)value), using sperm length as a male marker. After copulation, the S(2)values in the singlet and doublet spermathecae differed significantly, indicating differential sperm storage during copulation. Postcopulatory treatment affected differential sperm storage significantly. Females dissected immediately had lower S(2)values in the doublet than in the singlet spermatheca, while females left awake showed the reverse pattern for the same two males. This reversal did not occur when females were treated with carbon dioxide. The results indicate differential storage of sperm from different males during copulation and that female muscular activity can affect storage and separation of competing ejaculates beyond copulation. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed2000

Male-male competition and large size mating advantage in European earwigs, Forficula auricularia.

European earwigs are sexually dimorphic in forceps shape and length. Male forceps are thought to be weapons in male contests for access to females, but recent findings suggest that females choose males on the basis of their forceps length. I investigated sexual selection on forceps length and body size and the occurrence of male-male competition. When I controlled for forceps length experimentally and statistically, relatively heavy males had greater copulation success than relatively light males. When I controlled for body size, males with relatively longer forceps had no tendency for greater copulation success than males with shorter forceps. Relatively heavy males more often took over copulations from smaller males than vice versa. Male contests were important for the outcome of mate competition, as males commonly interrupted and took over copulations. My results therefore suggest that intrasexual selection is significant in competition for copulations in male earwigs, and acts on body size. This contrasts with previous findings, which have shown intersexual selection on forceps length to be important. However, both modes of sexual selection may be acting through a two-stage process, where male-male competition first determines which males have access to females, and then through female choice among available males. Morphological measurements supported the conclusion that forceps length and body size are male secondary sexual characters, as these characters had large variance and skewed distributions in males, but were normally distributed in females. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1990

Spinal block reveals roles for brain and spinal cord in the mediation of reflexive penile erections in rats.

Five experiments were addressed at two questions: (1) is the influence of the brain on spinal control of reflexive erection exclusively inhibitory; and (2) are the effects of copulation on erectile potential mediated by the brain, the spinal cord, or both? After various amounts of antecedent copulation, spinal anesthesia was induced in male rats by tetracaine (TET) injected through chronically implanted cannulae into the thoracic or lumbar spinal subarachnoid space, and the animals were then tested for reflexive penile erections (supine position, penile sheath retracted, no phasic stimulation applied). In sexually rested rats, TET injected at either T4 or T10 reduced reflex latency but also reduced the number and intensity of responses. Penile erection was inhibited by TET injected at L5, the region of the cord receiving sensory and motor projections from the genitalia. In previous studies surgical transection of the thoracic cord facilitated erection latency and production. In the present experiments the divergent effects of intrathecal TET on these variables suggested that they are controlled by separate systems within the spinal cord and that in the sexually rested rat the net influence of the brain is to inhibit the latency system and excite the production system. After rats copulated to sexual satiety, thoracic spinal block did not reverse the complete abolition of reflexive erections, establishing for the first time that copulation has direct inhibitory effects on the spinal cord's intrinsic system. Fewer antecedent ejaculations had less inhibitory effects on reflexive erection, and TET then acted, as in rested males, to reduce the erection latency and the number of erections, indicating that copulation may act on the brain's descending influences on spinal systems. The overall pattern of results suggested that the brain exerts both excitatory and inhibitory influences on separate, interacting spinal mechanisms that regulate the latency to reflexive erection and the number and intensity of erections displayed.

Anesthesia, Spinal↗
PubMed1990

Dopamine receptors in the ventral tegmental area modulate male sexual behavior in rats.

The mesocorticolimbic dopamine tract is considered to be a substrate for motivation and reward as well as for locomotor behavior. The present experiments assessed the role of dopamine cell bodies in the ventral tegmental area (VTA), the source of this tract, in the copulatory behavior of male rats. The dopamine agonist apomorphine or the dopamine antagonist cis-flupenthixol were microinjected into the VTA immediately before sexual behavior tests with a receptive female. Apomorphine delayed the onset of copulation and slowed its rate, presumably by stimulating somatodendritic autoreceptors and thereby decreasing the firing rate of VTA neurons. Control injections of apomorphine into the substantia nigra were without effect. cis-Flupenthixol, which would have blocked autoreceptors and thereby depolarized VTA neurons, shortened the latency to begin copulating in those animals that did copulate; however, fewer animals exhibited sexual behavior. One possible explanation for the apparently contradictory effects of cis-flupenthixol may be that VTA neurons increased their rate of firing in some animals, leading to a faster onset of copulation, but that in other animals depolarization block in a substantial number of neurons resulted in a lack of copulation. These results are consistent with a contribution of the mesocorticolimbic dopamine tract to motivational and/or motor aspects of male copulatory behavior.

Action Potentials↗
PubMed1986

The endocrine control of reproduction and molt in male and female emperor (Aptenodytes forsteri) and adelie (Pygoscelis adeliae) penguins. I. Annual changes in plasma levels of gonadal steroids and LH.

Changes in plasma LH, testosterone, and estrogens were investigated throughout reproduction and molt in free-living male and female emperor (Aptenodytes forsteri) and adelie (Pygoscelis adeliae) penguins. In both sexes and species, plasma LH and gonadal steroids were severalfold above basal level at the time of arrival on the breeding grounds, suggesting that environmental cues (especially decreasing daylength in emperors) rather than mating and courting primarily stimulate gonadal development and reproduction. In both species a marked increase in plasma LH (both sexes), testosterone (males), and estrogens (females) corresponded with the time of maximum gonadal size, and peak values were obtained at the time of copulation, i.e., in emperors about 10-15 days prior to egg laying. In females, plasma LH and estrogens dropped to low levels between copulation and egg laying. Similarly, following copulation in males plasma testosterone fell to lower levels that in emperors were maintained during incubation and brooding of the non-thermally emancipated chick. Plasma LH levels followed the same trend as testosterone, falling after copulation and falling further prior to molt. Though lower than at copulation, plasma LH was higher in incubating (males) and brooding (males and females) emperors than during rearing of the thermally emancipated chicks, suggesting that plasma LH might be related to incubating, brooding, and territorial behavior. In male and female emperors and in male adelies, plasma gonadal steroids and LH were at basal levels throughout molt.

Animals↗
PubMed2005

Males mate guard in absentia through extended effects of postcopulatory courtship in the parasitoid wasp Spalangia endius (Hymenoptera: Pteromalidae).

The proximal mechanisms leading to monandry have been little studied in most insect orders, including Hymenoptera. In the parasitoid wasp Spalangia endius, mated females are less attractive (less often mounted) than virgins and are unreceptive (unlikely to allow copulation). Which aspects of mating are responsible was tested by observing male responses toward females whose mating had been interrupted at various stages. All females were allowed to receive precopulatory courtship and to open their genital aperture to copulate. Then some were interrupted before copulation, some after copulation but before postcopulatory courtship, and some were allowed to complete postcopulatory courtship. Females that had copulated were not less attractive than females that had not. In contrast, females that had received postcopulatory courtship were clearly both less attractive and less receptive. Thus, postcopulatory courtship functions as extended mate guarding, by making the female less attractive and less receptive to subsequent males even after the original male is no longer present. The effect of postcopulatory courtship on female attractiveness was persistent but imperfect: when males were presented sequentially to mated females, most but not all males retreated without mounting, and a female could repulse more than twenty males in succession.

Animals↗
PubMed2000

The influence of self-fertilization and pairing on life-history traits in the freshwater snail Bulinus forskalii (Gastropoda, planorbidae).

This study analyses the basic reproductive biology of the schistosonie-vector snail Bulinus forskalli. This hermaphroditic species can self-fertilize. Variation of the mating system was analysed in two populations from Cameroon in a three-step experiment. (i) The fecundity (number of eggs and of egg capsules) of isolated virgin individuals from both populations was followed over a month, as well as the survival of offspring from these individuals. Estimates of these parameters were intermediate. Our results also indicate that inbreeding depression has a maximum value of about one-half in both populations. No difference was observed between populations for both the overall fecundity of adults and survival of offspring. (ii) Individuals were then paired either within, or between populations over three successive days, and the number of copulations recorded. Copulations were observed in all situations, including between-population pairs. No significant dlifference in the number of copulations per pair was detected. However, this value decreased with time, and reciprocal copulations were significantly less numerous between than within populations. (iii) Individuals that successfully copulated as female in (ii) were isolated, and their fecundity was followed over 3 weeks. The fecundity of individuals that had been maintained isolated over the whole experiment served as a control. No significant difference was on the whole detected. Our results collectively suggest that the individuals from the two populations studied are rather selfers, confirming that B. forskalii is a preferentially selfing species. There is also some pre-zygotic isolation against crosses between populations.

Animals↗
PubMed2001

Target-dependent differentiation and development of molluscan neurons and neuroendocrine cells: use of parasitisation as a tool.

Specimens of the freshwater snail Lymnaea stagnalis infected with the schistosome parasite Trichobilharzia ocellata show a strongly inhibited development of their reproductive tract. We hypothesised that the effects of the underdevelopment of targets are reflected at the level of the neuronal development of (i) the motor neurons innervating the male copulation organ and (ii) neuroendocrine cells regulating the gonad. We determined the state of neuronal development by measuring cell number, cell size and neuropeptide gene expression. Our results show that the neuronal development of both copulation controlling anterior lobe motor neurons of the right cerebral ganglion and neuroendocrine caudodorsal cells, which produce neuropeptides regulating ovulation, egg laying and accompanying behaviour, are affected in parasitised animals in which their respective target organs were not developed. The cell bodies were smaller and fewer cells were found to express neuropeptide genes compared to those in non-parasitised animals. These effects were not observed in the appropriate controls. Backfills and lesions of the penis nerve have shown that the inhibited development of central motor neurons in parasitised snails is target dependent; neighbouring neurons that have no connection with the male copulation organ are not affected. Our data suggest that this effect is established by target-derived neurotrophic factors that need this connection for being transported to the innervating motor neurons. We propose that the effect on the neuroendocrine caudodorsal cells is mediated by a humoral factor, since they have no known connection with their target. We have shown that the size and gene expression of motor neurons controlling copulation behaviour in the pond snail Lymnaea stagnalis are related to the size of their target, the copulation organ, and depend on the connection with this target.

Animals↗