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PubMed2003

Effects of four generations of density-dependent selection on life history traits and their plasticity in a clonally propagated plant.

Life history evolution of many clonal plants takes place with long periods of exclusively clonal reproduction and under largely varying ramet densities resulting from clonal reproduction. We asked whether life history traits of the clonal herb Ranunculus reptans respond to density-dependent selection, and whether plasticity in these traits is adaptive. After four generations of exclusively clonal propagation of 16 low and 16 high ramet-density lines, we studied life history traits and their plasticities at two test ramet-densities. Plastic responses to higher test-density consisted of a shift from sexual to vegetative reproduction, and reduced flower production, plant size, branching frequency, and lengths of leaves and internodes. Plants of high-density lines tended to have longer leaves, and under high test-density branched less frequently than those of low-density lines. Directions of these selection responses indicate that the observed plastic branching response is adaptive, whereas the plastic leaf length response is not. The reverse branching frequency pattern at low test-density, where plants of high-density lines branched more frequently than those of low-density lines, indicates evolution of plasticity in branching. Moreover, when grown under less stressful low test-density, plants of high-density lines tended to grow larger than the ones of low-density lines. We conclude that ramet density affects clonal life-history evolution and that under exclusively clonal propagation clonal life-history traits and their plasticities evolve differently at different ramet densities.

Adaptation, Biological↗
PubMed1999

Involvement of serotoninergic pathways in the control of luteinizing hormone secretion in red deer hinds.

Two experiments were conducted to determine whether serotoninergic pathways, which are implicated in the neuroendocrine regulation of luteininzing hormone (LH) secretion in domestic animals, have a similar action in red deer hinds. In the non-breeding season (August), ovariectomized (n = 5) and ovariectomized-thyroidectomized (n = 5) hinds received a vehicle solution followed 4 h later by either serotonin (66 microg kg(-1) i.v.) every 10 min for a further 4 h or the serotonin antagonist, cyproheptadine (3 mg kg(-1) i.v.) as a single injection. This procedure was repeated in the breeding season (June). In the non-breeding season serotonin was without effect, but cyproheptadine reduced LH pulse frequency and amplitude in ovariectomized-thyroidectomized hinds (P<0.01). During the breeding season, serotonin reduced LH pulse amplitude in ovariectomized hinds (P<0.05) and cyproheptadine reduced LH pulse frequency in both ovariectomized and ovariectomized-thyroidectomized hinds (P<0.05 and P<0.01, respectively). On each occasion, cyproheptadine increased (P<0.01) plasma prolactin concentration, whereas serotonin had no effect. These results indicate a stimulatory role for serotoninergic neurons on the hypothalamic GnRH pulse generator mechanism of red deer hinds during the breeding season. In a second experiment, the LH response to GnRH (5 microg i.v.) was examined in ovariectomized hinds (n = 5) following administration of a serotonin infusion (6.6 microg kg(-1) min(-1) i.v. for 15 min), cyproheptadine (3 mg kg(-1) i.v. as a single dose) or vehicle, in the breeding season (July) after induction of halothane anaesthesia and in the non-breeding season (December) without anaesthesia. Halothane anaesthesia eliminated endogenous pulses of LH. In comparison with the vehicle-treated controls, the response of plasma LH to exogenous GnRH was not altered by serotonin or cyproheptadine in either season, which shows that serotonin has no effect on LH release at the pituitary gland level in these animals. It was concluded that in the regulation of LH release in red deer hinds, serotoninergic pathways have a stimulatory role operating at the hypothalamic level.

Anesthesia↗
PubMed1992

Duration of the cycle of the seminiferous epithelium and quantitative histology of the testis of the South American white-belly opossum (Didelphis albiventris), Marsupialia.

The duration of the cycle of the seminiferous epithelium of the South American white-belly opossum, as obtained by autoradiography after intratesticular injection of tritiated thymidine, was estimated to be 17.3 +/- 0.1 days (mean +/- s.d.). Quantitative histological analysis was performed on testes from animals caught both in mating and non-mating periods of the annual reproductive cycle. Significant differences were found in the volumetric proportion of Leydig cells, but the spermatogenic yield remained constant throughout the year. The numerical ratio between type A spermatogonia and zygotene primary spermatocytes (1:12.0), as well as daily sperm production (4.8 x 10(6) sperm cells per g of testis parenchyma per day), were found to be lower than those reported in most eutherian mammals.

Animals↗
PubMed2006

Childhood sexual abuse (CSA) experiences: an underestimated factor in perinatal care.

BACKGROUND: Childhood sexual abuse can have several negative consequences on pregnancy, birth, and the early neonatal period. However, most obstetricians are not aware if their patients have a history of childhood sexual abuse. We therefore investigated childhood sexual abuse experiences in 226 women three to eight months after delivery of a healthy child. METHODS: 415 women were approached to answer a self-administered questionnaire including obstetrical questions and questions focusing on abuse experiences. 320 women agreed to participate, 226 (69.1% of the women fulfilling inclusion criteria) of which returned a completed questionnaire. Sexual abuse was explored using a modified version of a questionnaire developed by Wyatt. The complete questionnaire was designed in cooperation with the German "Frauennotruf", a society providing care for victims of sexual abuse. RESULTS: The prevalence of childhood sexual abuse was a minimum of 11.5% and a maximum of 14.6% if women who were not sure about such experiences during their childhood were included. Another 1.3% of the women had experienced sexual abuse as an adult. Lifetime sexual abuse prevalence was 12.8% and 15.9%, respectively. Of the women with an experience of childhood sexual abuse, 42.3% mentioned an ongoing abuse situation for at least six months. CONCLUSIONS: As approximately every 9th woman presenting for obstetrical care has experienced childhood sexual abuse, and as those experiences may have a negative impact on fetal and maternal well-being, adequate counseling models should be offered to victims of sexual abuse.

Adolescent↗
PubMedDate not supplied

Changes in the performance of parkinsonian patients and normal aged on the Benton Visual Retention Test.

Performance on the Benton Visual Retention Test was compared between those with Parkinson's disease (PD) and age-equivalent controls. The major difference between groups was that those with PD showed an increase in figural reproduction errors between test periods spaced six months apart, while controls showed little increase in errors over this time and made fewer errors at each time of testing. Age and IQ accounted for major proportions of variance in performance for both groups (about 50%), far more than that attributable to group membership. Within the PD group, however, age and disease onset were confounded (r = .92), indicating that age as a variable is quite when disease onset is considered. The results support the notion that PD is associated with change in visual-spatial memory, beyond that predicted by age per se.

Adult↗
PubMed2006

Gamete/embryo - oviduct interactions: implications on in vitro culture.

Fertilization and development of mouse embryos occur in the oviduct. Accumulating data suggested that embryo-maternal communication exists in the preimplantation period, with the female reproductive tract providing the optimal microenvironment conducive to the development of embryos. Signals produced from the developing embryos not only affect their own transport in the oviduct, but the physiology and gene expression patterns of the oviduct. As a step towards understanding the action of embryos on oviductal physiology, both genomics and proteomics approaches are being used to unveil the underlying mechanism of embryo-maternal interaction at the preimplantation stage. Results from recent studies allow us to better understand the roles and the use of oviductal secretory proteins or factors that affect embryo development in vivo and in vitro. It has been shown that in vitro culture alters gene expression of the cultured embryos and may predispose the embryo to certain disease. Therefore, the interaction between gamete/embryo and oviduct in vitro and in vivo, and the long-term effects of embryo culture on foetal development warrant further investigation.

Animals↗
PubMed2005

Elevated prolactin levels in male youths treated with risperidone and quetiapine.

The aim of this study was to report on the serum prolactin levels in 70 male youths at a residential treatment center who were treated with either risperidone or quetiapine. This is a cross-sectional retrospective medical chart review of 50 males (mean age, 13.5+/-2.8 years) treated with risperidone (mean dose, 2.4+/-1.6 mg/day) and 20 males (mean age, 13.5+/-2.4 years) treated with quetiapine (mean dose, 317.5+/-238 mg/day). Serum prolactin levels were drawn according to a protocol, after at least 6 weeks of treatment. Prolactin was above the upper limit of normal for 68% of the patients on risperidone and 20% of the patients on quetiapine (chi2 analysis: R>Q; p<0.001). Both risperidone and quetiapine produced dose-related increases in serum prolactin levels (R, r=0.34, p=0.017; Q, r=0.45, p=0.05). No correlation was found between duration of treatment and prolactin levels. Given that hyperprolactinemia secondary to antipsychotic treatment may result in reproductive and growth irregularities, periodic long-term monitoring during treatment with these two atypical antipsychotics (and perhaps others as well) may be warranted.

Adolescent↗
PubMed2006

Flowering phenology and wind-pollination efficacy of heterodichogamous Juglans mandshurica (Juglandaceae).

BACKGROUND AND AIMS: Heterodichogamy differs from normal dichogamy, in that it involves two mating types (protogyny and protandry) that occur at a 1 : 1 ratio in a population. Flowering phases of the two mating types are synchronized and reciprocal, which was considered to ensure between-type outcrossing. This study aims to quantify the flowering pattern and pollination efficacy in Juglans mandshurica, a wind-pollinated heterodichogamous tree. METHODS: The pattern of flowering phenology was monitored within individual trees and pollen traps were used to measure air-borne pollen loads during the spring in 2003 and 2004. Pollen longevity was determined by staining technique. Also a pollen supplementation experiment was performed in 2004 to assess pollen limitation of fruit production. KEY RESULTS: There was no overlap between sexual functions within individual trees. Flowering periods of the two mating types were reciprocal and synchronous in both 2003 and 2004. Air-borne pollen loads were large, and protogynous and protandrous individuals each produced a high pollination peak, consistent with the two blooming periods. Maximum pollen longevity was about 4 h for protandrous individuals, and 3 h for protogynous individuals. Pollen supplementation did not increase fruit production in either protogynous or protandrous individuals. CONCLUSIONS: Heterodichogamous flowering in Juglans mandshurica effectively avoids selfing, promotes between-type outcrossing, and leads to efficient pollination in a natural population.

Breeding↗
PubMed2000

High frequency of sub-optimal semen quality in an unselected population of young men.

Male reproductive function seems to have deteriorated considerably during the past 4-5 decades. However, studies of the reproductive function in unselected populations have not previously been reported. As the large majority of young men in Denmark are subjected to a compulsory medical examination for military service, this provided a unique opportunity to study the reproductive function in an unbiased population. Altogether 891 young men delivered a blood sample in which reproductive hormones were measured. From 708 of these men data were also obtained on semen quality and testis size. The median sperm concentration was 41 x 10(6)/ml (mean 57.4 x 10(6)/ml). Men with ejaculation abstinence above 48 h had slightly higher sperm concentrations (median 45 x10(6)/ml, mean 63.2 x 10(6)/ml), but even in this subgroup, 21 and 43% respectively had sperm counts below 20 x 10(6)/ml and 40 x 10(6)/ml. Among men with no history of reproductive diseases and a period of abstinence above 48 h, as many as 18 and 40% respectively had concentrations below 20 and 40 x 10(6)/ml. Sperm counts were positively correlated with testis size, percentage normal spermatozoa and inhibin B, and negatively correlated with percentage immotile spermatozoa and follicle stimulating hormone. Possible causes for this high frequency of young men with suboptimal semen quality are obscure and need to be explored. Whether these findings apply for young male populations of comparable countries remains to be seen.

Analysis of Variance↗
PubMed2000

Counselling couples and donors for oocyte donation: the decision to use either known or anonymous oocytes.

In order to avoid a long waiting period, the Centre for Reproductive Medicine of the Free University of Brussels suggests that couples in need of donor oocytes search for a donor among family and friends. Recipient couples can choose between two types of donation: known donation, i.e. treatment with the oocytes of the donor recruited by the couple, or anonymous donation, i.e. an exchange of the donor recruited by the couple with a donor recruited by another couple in order to ensure anonymity between donor and recipients. In total, 144 couples were counselled by a psychologist in the decision-making process with regard to the kind of donation to be used. Some 68.8% of the recipient couples preferred known donation. This choice was mainly motivated by reasons related to fears associated with anonymity, such as fear of the unknown origin of genetic material and the trust that couples had in 'their' donor. Almost one-third of the couples opted to use anonymous oocytes. The desire to establish explicit boundaries between the two families involved was the major motivation for this choice. Approximately 44% of the couples were willing to tell the child about the oocyte donation.

Adult↗
PubMed2003

Evaluation of the growth response of six invasive species to past, present and future atmospheric carbon dioxide.

The response of plant species to future atmospheric carbon dioxide concentrations [CO(2)] has been determined for hundreds of crop and tree species. However, no data are currently available regarding the response of invasive weedy species to past or future atmospheric [CO(2)]. In the current study, the growth of six species which are widely recognized as among the most invasive weeds in the continental United States, Canada thistle (Cirsium arvense (L.) Scop.), field bindweed (Convolvulus arvensis L.), leafy spurge (Euphorbia esula L.), perennial sowthistle (Sonchus arvensis L.), spotted knapweed (Centaurea maculosa Lam.), and yellow star thistle (Centaurea solstitialis L.) were grown from seed at either 284, 380 or 719 micromol mol(-1) [CO(2)] until the onset of sexual reproduction (i.e. the vegetative period). The CO(2) concentrations corresponded roughly to the CO(2) concentrations which existed at the beginning of the 20th century, the current [CO(2)], and the future [CO(2)] projected for the end of the 21st century, respectively. The average stimulation of plant biomass among invasive species from current to future [CO(2)] averaged 46%, with the largest response (+72%) observed for Canada thistle. However, the growth response among these species to the recent [CO(2)] increase during the 20th century was significantly higher, averaging 110%, with Canada thistle again (+180%) showing the largest response. Overall, the CO(2)-induced stimulation of growth for these species during the 20th century (285-382 micromol mol(-1)) was about 3x greater than for any species examined previously. Although additional data are needed, the current study suggests the possibility that recent increases in atmospheric CO(2) during the 20th century may have been a factor in the selection of these species.

Atmosphere↗
PubMed1991

Temporal sequence of neuroendocrine events associated with the transfer of male golden hamsters from a stimulatory to a nonstimulatory photoperiod.

The transfer of male golden hamsters from long day (LD) to short day (SD) conditions results in gonadal atrophy within 8 weeks and significant reductions in LH, FSH, and prolactin (Prl) secretion as early as 4 weeks. Changes in hypothalamic neurotransmitter metabolism precede these changes in pituitary hormone secretion. Thus median eminence norepinephrine (NE) turnover declines steadily after SD exposure, although the differences as compared to turnover in LD hamsters are not significant until Week 4. Median eminence dopamine (DA) turnover is reduced significantly within 1 week. Turnover of NE and DA in the medial basal hypothalamus also changes significantly within 1 or 2 weeks of SD exposure, but the changes are not maintained through Week 8, despite continued reductions in levels of circulating LH, FSH, and Prl. Reductions in median eminence NE metabolism appear to be responsible for the decrease in LH and FSH release. Initial decreases in Prl release appear to be hypothalamic in origin, but the hypothalamic factor(s) responsible for this change is not evident. An increase in inhibitory input from tuberoinfundibular dopaminergic neurons is clearly not involved.

Animals↗
PubMed1997

Gonadotropin-releasing hormone neural projections to the systemic vasculature during sexual maturation and delayed puberty in the male Djungarian hamster.

To study GnRH neuron projections to the systemic circulation during sexual maturation and in photoperiod-induced delayed puberty, we injected fluorogold (i.p.) into long- or short-day-reared male Djungarian hamsters. Five days after fluorogold treatment, at 15, 25, or 40 days of age, most GnRH neurons were found to access the systemic vasculature from terminal fields in the median eminence and organum vasculosum of the lamina terminalis. More than 80% of GnRH cell bodies in the medial preoptic area and diagonal band of Broca contained fluorogold, the locus for the majority of the GnRH neuron system in this species. GnRH cell numbers (approximately 180) and percentages with fluorogold were the same in 15- and 25-day-old males in long days, respectively pre-and peripubertal, and were not different from that in short-day hamsters with delayed puberty. Neither the number of fluorogold-labeled GnRH somata nor intensity of the fluorogold per cell was altered in hamsters during the critical period for initiation of reproductive maturation. Only later, at age 40 days, was the percentage of GnRH somata with fluorogold increased in long-day hamsters or reduced in 40-day-old males in short days relative to that in males at 15 days of age (same day length). The findings indicate that GnRH neuron projections to regions outside the blood-brain barrier are established before puberty and are independent of photoperiod control of reproductive development.

Animals↗
PubMed2000

Genetic evidence for assortative mating between 13-year cicadas and sympatric "17-year cicadas with 13-year life cycles" provides support for allochronic speciation.

Thirteen-year cicadas of brood XIX from northern Arkansas, Missouri, and southern Illinois (lineage A) are known to be genetically different at two marker loci (mitochondrial DNA and abdominal color) from 13-year cicadas to the south (lineage B) that emerge in the same year. Because 17-year cicadas from all broods (year classes) are indistinguishable from lineage A at these two marker loci, previous workers suggested that the lineage A cicadas of 13-year brood XIX were derived from 17-year cicadas by life-cycle switching (allochrony). Data presented here show that, over the same northern geographic range, lineage A is also present in 13-year cicadas belonging to brood XXIII (which always emerges four years later than brood XIX). Detailed sampling along the putative life-cycle-switching boundary in 13-year brood XXIII revealed a previously unsuspected broad zone of overlap where populations contained individuals of both lineages A and B. Despite this sympatry, and previous reports of a lack of behavioral barriers to interbreeding, a strong correlation between mitochondrial haplotype and abdominal color suggests that assortative mating has taken place. Lineage A 13-year cicadas from both broods XIX and XXIII are only found within a gap in the spatial distribution of 17-year cicadas. This, in combination with the lack of differentiation between lineage A 13- and 17-year cicadas at the marker loci and new behavioral data for 13-year brood XIX, suggests a recent derivation of all northern 13-year cicadas from the 17-year cicadas via life-cycle switching. We discuss the implications of these allochronic shifts for speciation.

Animals↗
PubMedDate not supplied

Testicular function and fertility in men with homozygous alpha-1 antitrypsin deficiency.

Fertility and testicular function were studied in eight men with severe homozygous (Pi ZZ variant genotype) alpha-1 antitrypsin (AAT) deficiency. Age- and marital duration standardized fertility, clinical androgenic features, mean testicular volume, plasma luteinizing hormone (LH) and follicle-stimulating hormone (FSH) and semen analysis were all normal apart from a reduction in semen volume. Mean plasma total and free testosterone were elevated and the percentage free testosterone reduced compared with age-matched, healthy fertile controls indicative of increased sex-hormone binding globulin (SHBG) levels representing an early marker for subclinical hepatic dysfunction associated with AAT-deficiency. In view of the preservation of normal fertility and testicular function despite chronic respiratory disease and premature death with deleterious AAT gene variants, it is proposed that the high prevalence of genetic polymorphism in the AAT protein may be maintained by the chronological asynchrony of the periods of maximal male reproductive activity (40 years) and the late onset (greater than 40 years) of symptoms in severe AAT deficiency rather than by any balance between reduced reproductive fitness of homozygotes and heterozygote advantage.

Fertility↗