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PubMed1997

Plant reproduction during spaceflight: importance of the gaseous environment.

Plant reproduction is a complex developmental process likely to be disrupted by the unusual environmental conditions in orbital spacecraft. Previous results, reviewed herein, indicated difficulties in obtaining successful seen production in orbit, often relating to delayed plant development during the long-term growth necessary for a complete plant life cycle. Using short-duration exposure to spaceflight, we studied plant reproduction in Arabidopsis thaliana (L.) Heynh, during three flight experiments: CHROMEX-03 on STS-54 (6 d), CHROMEX-04 on STS-51 (10 d), and CHROMEX-05 on STS-68 (11 d). Plants were 13 - 14 d old (rosettes) at time of launch and initiated flowering shoots while in orbit. Plants were retrieved from the orbiters 2 - 3 h after landing and reproductive material was immediately processed for in-vivo observations of pollen viability, pollen tube growth, and esterase activity in the stigma, or fixed for later microscopy. Plants produced equal numbers of flowers to those controls growing on the ground but required special environmental conditions to permit fertilization and early seed development during spaceflight. In CHROMEX-03, plants were grown in closed plant growth chambers (PGCs), and male and female gametophyte development aborted at an early stage in the flight material. In CHROMEX-04, carbon dioxide enrichment was provided to the closed PGCs and reproductive development proceeded normally until the pollination stage, when there was an obstacle to pollen transfer in the spaceflight material. In CHROMEX-05, an air-exchange system was used to provide a slow purging of the PGCs with filtered cabin air. Under these conditions, the spaceflight plants apparently had reproductive development comparable to the ground controls, and immature seeds were produced. In every aspect examined, these seeds are similar to those produced by the ground control plants. The results suggest that if the physical environment around the plant under spaceflight conditions meets the physiological demands of the plant, then reproductive development can proceed normally on orbit.

Arabidopsis↗

PubMed2000

Genetic evidence for gonochoristic reproduction in gynogenetic silver crucian carp (Carassius auratus gibelio bloch) as revealed by RAPD assays.

Sex evolution has been a debating focus in evolutionary genetics. In lower vertebrates of reptiles, amphibians, and fish, a species or a bioform reproduces either sexually or asexually but never both. A few species were found to consist of all females in fish. These all-female species can propagate by asexual reproduction modes, such as gynogenesis and hybridogenesis. However, the coexistence of sexuality and asexuality in a single species was recently noted only in a cyprinid fish silver crucian carp, Carassius auratus gibelio. This fish had been demonstrated to be capable of gynogenesis stimulated by sperm from other related species. Surprisingly, natural populations of this fish consist of a minor but significant portion (approx. 20%) of males. As different clones with specific phenotypic and genetic characteristics have been found, and RAPD markers specific to each clone have recently been identified, this fish offers many advantages for analyzing whether or not genetic recombination occurs between different clones. In this study, artificial propagation was performed in clone F and clone D. Ovulated eggs from clone F were divided into two parts and respectively inseminated with sperm from a clone D male and from a red common carp (Cyprinus carpio) male. The control clone D individuals were selected from gynogenetic offspring of clone D activated by sperm of red common carp. The phenotype and sex ratio in the experimental groups were also observed. Using RAPD molecular markers, which allow for reliable discrimination and genetic analysis of different clones, we have revealed direct molecular evidence for gonochoristic reproduction in the gynogenetic silver crucian carp and confirmed a previous hypothesis that the silver crucian carp might reproduce both gynogenetically and gonochoristically. Therefore, we conclude that the silver crucian carp possesses two reproductive modes, i.e., gynogenetic and gonochoristic reproduction. The response mechanism of two reproductive development modes may be the first discovery in vertebrates. Additionally, we discuss the evolutionary implication between gynogenetic and gonochoristic reproduction modes and the contribution of the minor proportion of males to genetic flexibility in the gynogenetic silver crucian carp.

Animals↗

PubMed2001

Social dominance, task performance and nutrition: implications for reproduction in eusocial wasps.

Dominance status is associated with individual differences in reproductive capacity in many animal societies, but the mechanisms that link social dominance to reproductive physiology are poorly understood. We propose a model for social dynamics that incorporates the nutritional costs and benefits of behavior: dominant individuals avoid energy-expensive behavior and build their nutritional reserves, thereby increasing their potential for reproduction. Greater reproductive capacity, once achieved, favors increased social dominance. To test the model, we measured relationships of females' nutrient storage and reproductive capacities with dominance status and task performance in the eusocial wasp Mischocyttarus mastigophorus. Ovary development was positively related with high levels of nutrient storage and with high rates of dominance behavior, but was not correlated with task performance. In contrast, high levels of nutrient storage were positively related with the performance of nutrient garnering and conserving tasks, but not with dominance behavior. These data support a model which places the nutritional costs of task performance as an intermediate causal link that connects dominance status with the accumulation of nutrient stores. Nutrient flow may be a general causal mechanism linking dominance status to reproductive capacity in animal societies.

Animal Nutritional Physiological Phenomena↗

PubMed2004

Influences of the feeding ecology on body mass and possible implications for reproduction in the edible dormouse (Glis glis).

The edible dormouse (Glis glis) is a small rodent and an obligate hibernator. Dormice undergo strong fluctuations of reproductive output during years that seem to be timed to coincide with future food supply. This behaviour enables them to avoid producing young that will starve with a high probability due to food shortage, and to increase their lifetime reproductive success. Aims of this study were to elucidate the extent to which feeding ecology in the edible dormouse has an impact on body mass and the fatty acid (FA) pattern of the white adipose tissue (WAT) before and after hibernation, which in turn might influence reproductive status in spring. Dormice show strong seasonal fluctuations of the body mass, which is reduced by one third during hibernation. Body mass and its changes depend on autumnal food availability as well as on the dietary FA pattern. During the pre-hibernation fattening period, dormice eat lipid rich food with a high content of linoleic acid. During hibernation, linoleic acid content is slightly but significantly reduced and body mass loss during winter is negatively correlated with the pre-hibernation linoleic acid content in the WAT. No relation between reproductive status and body mass, body condition or the FAs pattern of the WAT could be detected. However, in a year of high reproduction, dormice commence the shift to seed eating earlier than in a year of low reproduction. These seeds could be either a predictor for future food supply in autumn, or represent a high-energy food compensating high energetic costs of sexual activity in male edible dormice.

Adaptation, Physiological↗

PubMed2005

Positive effects of testosterone and immunochallenge on energy allocation to reproductive organs.

A number of studies have suggested the incompatibility of simultaneous increases in immune and reproductive functions. Other research has indicated that immune responses may be modulated depending on the relative benefits of increased survival and prospects for current and future reproduction. We tested the hypothesis that energy allocation to reproductive and other organ systems is not affected by testosterone level and energy expenditure on immune functions. Adult male white-footed mice (Peromyscus leucopus) with or without elevated testosterone levels and with or without immunochallenges were tested. Testosterone treatment was associated with reduced humoral immune response indicating immunosuppressive effects, reduced masses of gastrointestinal organs, reduced corticosterone level, increased kidney and seminal vesicle masses, and increased hematocrit. Immunochallenge was associated with increased resting metabolic rate and testes and seminal vesicle masses. Reproductive organ masses were greatest in immunochallenged mice with exogenous testosterone. Simultaneous increases in energy allocation to immune and reproductive structures may be an adaptive response that would enhance survival and current prospects for reproduction.

Animals↗

PubMed2002

Adaptive reproductive variation along a pollution gradient in a wolf spider.

When populations are exposed to environmental pollutants, growth and reproduction might be strongly reduced due to an increased detoxification effort. Sublethal metal pollution is therefore to be expected to cause the same selection pressure as a low resource habitat and might alter the reproductive strategy. Optimality models of life history theory predict that when resource availability is reduced, growth and reproductive output are reduced and that the release of fewer but larger propagules will be favoured. This was tested by applying a life history model to reproductive trait measurements in six populations of the wolf spider Pirata piraticus in which the assumptions of the model are satisfied. Internal Cd, Cu and Zn body burden were strongly correlated with each other, and differed strongly between the populations, indicating consistently differing metal exposure at the different sites. Pb levels were extremely variable within each population and did not differ between the populations. Females from populations with high concentrations of the first three heavy metals showed a strongly reduced reproductive output and fecundity, indicating a high reduction in resource availability due to detoxification processes. Egg size in contrast was negatively correlated with fecundity and reproductive output and as a consequence positively related with internal metal burden. Our results are thus in strong agreement with the predictions of the optimality models and confirm the benefits of a larger propagule size when resource availability is reduced.

Adaptation, Physiological↗

PubMed2003

Effects of forest fragmentation on male and female reproductive success in Cestrum parqui (Solanaceae).

In this paper we evaluate the effects of forest fragmentation on male (pollen removal, pollen load, and pollen tubes) and female reproductive success (fruit- and seed-set) of Cestrum parqui, a self-incompatible, pollination-specialist plant species. We also measure focal individual conspecific density to account for possible density-related effects that could influence the response variables. We calculate an index which incorporates male and female fitness and gives an integrated assessment of overall reproductive success. Forest fragmentation strongly affected the amount of pollen grains on stigmas and number of pollen tubes as well as seed-set, decreasing from continuous forest to small forest fragments, whereas focal individual conspecific density failed to explain any of the variability for the studied variables. Declines in overall reproductive success (i.e. male and female) in small forest fragments are ascribed to decreases in both the quality and quantity of pollination. Self-incompatibility coupled with a specialist pollination system may be particularly important traits determining the negative fragmentation effects observed in C. parqui. Logarithmic regression models described the behaviour of the variables along the fragmentation size gradient, allowing us to detect a threshold below which the effects of fragmentation begin to negatively affect reproductive success in C. parqui. Our results emphasize the importance of evaluating both components of the total plant fitness, as well as including simultaneously several aspects of pollination and reproduction processes when assessing the effects of forest fragmentation on plant reproductive success.

Cestrum↗

PubMed1992

Attitudes toward reproduction in a nonpatient population.

OBJECTIVE: A basic question to be answered in an attempt to understand human reproductive behavior as it manifests itself in clinical practice is, why do people want to have children? STUDY DESIGN: A psychometric instrument for the assessment of reproductive attitudes was developed. A total of 746 men and women at 20, 30, and 40 years of age, who were randomly selected from a nonpatient population, answered. Data were analyzed by factor analysis. Reproductive profiles were constructed. RESULTS: The two most important factors in both sexes were "children as existential satisfaction" and "children as lack of freedom," indicating a basic conflict. The third most important factor in both sexes was "the importance of one's own parents as examples in parenthood," supporting earlier findings that reproductive conflicts are transmitted from one generation to another. Reproductive profiles were uniform in the different age groups. CONCLUSION: The element of ambivalence may be a clue to a deeper understanding of human reproductive behavior.

Adult↗

PubMed1991

Seasonal reproduction in subtropical brahminy myna, Sturnus pagodarum: role of photoperiod.

Experiments were performed to study the extent of the involvement of photoperiod in the timing of seasonal reproduction in brahminy myna (Sturnus pagodarum). The reproductive cycle corresponds to annual variations in day length and there is a marked seasonal variation in the photogonadal response of birds, which is evident when birds are shifted from normal day length to long photoperiods (15L:9D) every month. This is supported by the results from constant long (15L:9D) and short (9L:15D) photoperiodic treatments. Whereas the reproductive cycle was abolished in short photoperiods, a 15L:9D photoperiod induced a single complete gonadal growth-involution cycle after which birds became photorefractory. Further, exposure of birds to 8L:16D during different phases of the reproductive cycle indicated that the effect of short photoperiods on advancement of photosensitivity depended on the reproductive status attained when shifting took place. These laboratory investigations clearly suggest that the annual photocycle affects the timing of the reproductive cycle of brahminy myna.

Animals↗

PubMed1992

Ovarian opioids and the reproductive cycle of the frog Rana esculenta.

In mammals, proopiomelanocortin-related peptides are involved in reproductive processes both at the hypothalamo-pituitary and ovarian levels. Using immunocytochemical, biochemical and physiological "in vitro" studies, we provide here evidence for a diffuse POMC-related opioid system in the frog Rana esculenta. Ovarian beta-endorphin (beta-EP) is expressed in thecal cells and changes during the reproductive cycle in an inverse relationship with follicular development. Seasonal changes in the ovary are different to those in the brain or in the pituitary. The ratio of acetylated vs native beta-EP in the ovary also changes over the reproductive period, affecting the biological activity of the peptide. During both the reproductive spring period and the summer post-reproductive phase pMol amounts of beta-EP stimulate follicular androgen secretion in vitro, in a naloxone-reversible way. In either period, an inhibition of estradiol, possibly mediated via other factors, is the result of opioid action. In conclusion, these data demonstrate for the first time the widespread presence of beta-EP-related peptides in the frog Rana esculenta. Both immunocytochemical and biochemical evidence, as well as in vitro responses, support a physiological role for beta-EP in ovarian seasonality during the reproductive cycle of this amphibian.

Amino Acid Sequence↗

PubMed1989

Reproductive toxicity of three phthalic acid esters in a continuous breeding protocol.

A continuous breeding protocol was utilized to examine the reproductive toxicity of three phthalate esters. CD-1 mice were given diets with either di-n-propyl phthalate (DPrP: 0.0, 1.25, 2.5, or 5.0%), di-n-pentyl phthalate (DPP: 0.0, 0.5, 1.25, or 2.5%), or di-n-octyl phthalate (DOP: 0.0, 1.25, 2.5, or 5.0%). Both male and female mice (20 pairs per treatment group, 40 pairs of control animals) were dosed for 7 days prior to and during a 98-day cohabitation period. Reproductive function was evaluated during the cohabitation period by measuring number of litters per pair, live pups per litter, and pup weight. There was no apparent effect on reproductive function in the animals exposed to DOP at dose levels sufficient to cause a significant increase in liver weight. Both DPP and DPrP were toxic to the reproductive system as evidenced by a complete inhibition of fertility at 1.25 and 2.5% DPP or 5.0% DPrP, and reduced fertility (litters/pair and live pups/litter, 0.5% DPP; live pups/litter, 2.5% DPrP). Toxicity of DPP had a strong male component and female component, whereas DPrP was more toxic to the female than the male reproductive system. DPP and DPrP treatment was associated with decreased body weight, increased liver weight, decreased testis and epididymis weights, decreased epididymal sperm concentration, and elevated seminiferous tubule atrophy. A comparison of seven phthalate esters tested using this continuous breeding protocol indicates the relative order of reproductive toxicity as diethylhexyl, dihexyl, dipentyl, dibutyl, dipropyl; diethyl and dioctyl are nontoxic.

Animals↗

PubMed1990

Assessment of ethylene glycol monobutyl and monophenyl ether reproductive toxicity using a continuous breeding protocol in Swiss CD-1 mice.

A continuous breeding reproduction study design was utilized to examine the reproductive toxicity of ethylene glycol monobutyl ether (EGBE) and ethylene glycol monophenyl ether (EGPE). Swiss CD-1 mice were administered EGBE in drinking water (0, 0.5, 1.0, and 2.0%, i.e., 0.7, 1.3, and 2.1 g/kg body wt/day) and EGPE was administered via the feed (0, 0.25, 1.25, and 2.5%, i.e., 0, 0.4, 2.0, and 4 g/kg body wt/day). Both male and female mice were dosed for 7 days prior to and during a 98-day cohabitation period. EGBE was toxic at the high (2%) and mid dose (1%) to adult F0 female mice: 13 out of 22 females at the high dose and 6 out of 20 at the mid dose died during the cohabitation period. Both the high- and mid-dose animals produced fewer litters/pair, fewer pups/litter, with decreased pup weight. These effects occurred in the presence of decreased body weight, decreased water consumption, and increased kidney weight. A crossover mating trial indicated that the reproductive effects could be attributed primarily to an effect on the female. This was substantiated at necropsy where testes and epididymis weights were normal as were sperm number and motility. Fertility of the offspring of the 0.5% group was normal in the presence of increased liver weights. With respect to EGPE, there was no change in the ability to produce five litters during the continuous breeding period. There was, however, a significant but small (10-15%) decrease in the number of pups/litter and in pup weight in the high-dose group. A crossover mating trial suggested a female component of the reproductive toxicity of EGPE. While fertility was only minimally compromised, severe neonatal toxicity was observed. By Day 21 there were only 8 out of 40 litters in the mid- and high-dose groups which had at least one male and female/litter. Second generation reproductive performance of the mid-dose group (1.25%) was unaffected except for a small decrease in live pup weight. In summary the reproductive toxicity of EGBE and EGPE was only evident in the female and occurred at doses which elicited general toxicity. EGBE was particularly toxic to adult female mice while EGPE was particularly toxic to immature mice of both sexes.

Animals↗

PubMed1990

Reproductive toxicity of a single dose of 1,3-dinitrobenzene in two ages of young adult male rats.

These studies evaluated the reproductive response and the possible influence of testicular maturation on the reproductive parameters, in male rats treated with 1,3-dinitrobenzene (m-DNB). Young adult male rats (75 or 105 days of age) were given a single oral dose of 0, 8, 16, 24, 32, or 48 mg/kg of m-DNB and killed at 14 days post-treatment. Mortality and neurotoxicity were observed at 48 mg/kg, but only in the older animals. Epididymis weight, testicular sperm head counts, cauda sperm reserves, and sperm morphology were affected at 16 and 24 mg/kg and higher in the older and younger animals, respectively. Testis weight and sperm motility were affected at 24 mg/kg and higher in both age groups. Histologic changes included maturation depletion of mid and late spermatids at 16 mg/kg and higher, atrophy of a few to many seminiferous tubules at 24 mg/kg and higher, and immature germ cells in the epididymis. The movement and/or mixing of luminal elements in the epididymis appeared to be influenced by severe testicular effects. In separate groups given only the 48 mg/kg dosage, fertilizing ability was lost by 5-6 weeks post-treatment and several animals failed to recover in 5 months. In the breeder males, minimal to extensive degrees of seminiferous tubule atrophy and sloughed germ cells in the epididymis were still present after 175 days. The studies indicated that the lowest dosage to produce reproductive changes was 16 mg/kg with a no-effect level of 8 mg/kg. A few animals suffered protracted or permanent reproductive damage. Since the older animals were more susceptible to both the general and the reproductive toxicity of m-DNB, the less severe reproductive changes in the younger animals cannot be attributed solely to maturational differences in the testis.

Aging↗

PubMed1990

Reproductive effects of diethylene glycol and diethylene glycol monoethyl ether in Swiss CD-1 mice assessed by a continuous breeding protocol.

Diethylene glycol (DEG) and diethylene glycol monoethyl ether (DEGEE) were evaluated for reproductive toxicity in CD-1 mice using a continuous breeding protocol. Compounds were administered in the drinking water at 0, 0.35, 1.75, and 3.5% w/v (DEG) or 0, 0.25 1.25, and 2.5% w/v (DEGEE). Exposure of the breeding pairs to 3.5% DEG for 14 weeks produced statistically significant decreases in the number of litters per pair, live pups per litter, proportion of pups born alive, and live pup weight. There was also a significant increase in the cumulative days to litter and a significant decrease in the number of pairs producing the third, fourth, and fifth litters for the 3.5% DEG-exposed mice. A crossover mating trial of the F0 mice to determine the affected sex was inconclusive, but suggested that offspring development was compromised in females exposed to 3.5% DEG. Slight maternal (F0) toxicity was noted for the 3.5 DEG group (7% decrease in body weight). The F1 generation, at 3.5% DEG, had decreased body weights at birth and exhibited poor postnatal survival. At the intermediate dose of DEG, body weights of both sexes were depressed at weaning, at onset of mating, and at necropsy. However, no adverse effects on reproduction were observed. DEGEE had no effect on reproduction in the F0 or F1 generation mice despite a 34% decrease in cauda epididymal sperm motility in the F1 males at 2.5% DEGEE. Other signs of toxicity observed in these F1 mice included increased relative liver weights. These data indicate that DEG is a reproductive toxicant in Swiss mice affecting fertility and reproductive performance, albeit at high doses (equivalent to 6.1 g/kg/day). However, its monoethyl derivative, DEGEE, is without adverse effects on fertility and reproductive performance.

Animals↗

PubMed1985

Modification of the pattern of central neurons by sensory inputs from the reproductive organs in Aplysia depilans L.

In the abdominal ganglion of Aplysia a number of motoneurons regulating visceral organs reacted to the stimulation of the reproductive organs. The response was mostly biphasic and often delayed. The multifunctional interneuron I (cell L10) reacted to the stimulation of the reproductive organs with burst firing, followed by an inhibitory phase. The interneuron II, involved in the regulation of visceral functions, was also activated during stimulation of the reproductive organs and its burst-pattern could be identified on a number of other neurons. Several members of the neurosecretory cell group reacted to the stimulation of reproductive organs. The response was, as a rule, biphasic and similar to the hormone action, long-lasting. Three further cells (near the cell L12, above the cell L21, and the neuron between R2 and R7 with unknown function) showed a stereotyped response to the stimulation of the reproductive organs. All the neurons reacting to the stimulation of the reproductive organs also received inputs from the cardiorenal system. The data support the existence of common networks composing variable units in the regulation of visceral functions of gastropods.

Action Potentials↗

PubMed1989

Expression of the egg-laying hormone genes in peripheral neurons and exocrine cells in the reproductive tract of the mollusc Lymnaea stagnalis.

The neuroendocrine caudodorsal cells play an important role in the control of reproduction in Lymnaea stagnalis. These neurons produce at least nine neuropeptides which are encoded by caudodorsal cell hormone-I and -II genes. The role of some of these peptides in the control of reproduction has been established. The present study demonstrates that the transcription and translation of the caudodorsal cell hormone genes also proceeds abundantly in the reproductive tract of this hermaphroditic animal. In the female part of the reproductive tract neurons were found to express gene I. These neurons are most likely involved in the control of transport of the eggs and egg-masses and in the regulation of secretory activity from the female accessory sex glands. In the male part of the reproductive tract exocrine secretory cells express gene I or gene II. The gene products are secreted into the male duct and transferred to the female copulant during copulation. Furthermore, putative sensory neurons in the skin were found to express gene I. The results indicate that in L. stagnalis the complex process of reproduction is regulated--at least in part--by a set of neuropeptides which are encoded by a small multigene family, viz. the caudodorsal cell gene family.

Animals↗

PubMed1984

Individual analysis of age-associated changes in reproductive activity and lifespan of Drosophila virilis.

In the TK strain of Drosophila virilis, age-associated changes in reproductive activities (copulating activity and fertility in males and egg-laying activity in females) and lifespan were examined in individual flies. The mean lifespan of individually aged flies was about 11 weeks for both males and females. Copulating activity was maximum in two-week old males, then decreased gradually and finally ended at the age of 13 weeks at which about half of males were still surviving. Females also had a peak in egg-laying activity at the age of two weeks while no eggs were laid by females older than ten weeks, although more than half of females were alive at the stage. Analyses of the relationship between reproductive activity and lifespan of individual flies revealed that shorter lived males exhibited a higher copulating activity in the early stage of their lives than longer lived males. In males whose lifespan was less than ten weeks the reproductive period increased with the lifespan while the post-reproductive period was almost constant (one to two weeks). In males living longer than ten weeks, the reproductive period remained constant (about eight weeks) while the post-reproductive period increased in parallel with the total lifespan. Similar tendencies were also observed in the egg-laying activity of female flies.

Aging↗

PubMed1984

Effects of waterborne iron on growth, reproduction, survival and haemoglobin in Daphnia magna.

The effects of waterborne iron (FeCl3 X 6H2O) on growth, reproduction, survival and haemoglobin content in Daphnia magna were studied from subnormal to toxic concentrations in hard reconstituted water. Low concentrations of iron stimulated reproduction and haemoglobin synthesis after chronic exposure for 21 days. Maximum reproduction occurred between 0.1 and 1 microgram Fe 1(-1). Juvenile growth was not stimulated by iron but was slightly inhibited between 1 and 8 micrograms Fe 1(-1) and above 128 micrograms Fe 1(-1). A slight inhibition of growth persisted for 21 days. Total haemoglobin content was above the control with no waterborne iron at all but one concentration (512 micrograms Fe 1(-1]. The highest value (3.8 X control value) was found at 2 micrograms Fe 1(-1). The haemoglobin content decreased between 64 and 512 micrograms Fe 1(-1) and increased at higher concentrations. The decrease coincided with an inhibited reproduction. The increase was found in non reproductive survivors. A comparison with a previous study in D. magna suggests that ambient conditions (hardness and pH) and ageing of the water are important for the effects of waterborne iron. At a hardness of 250 mg 1(-1) as CaCO3 and a pH range of 7.0-8.0 the ZEP (Zero Equivalent Point) for reproduction was 158 micrograms Fe 1(-1). Continuous exposure to higher concentrations is expected to lead to extinction of a D. magna population.

Animals↗