Effects of prostaglandin administration on ovarian follicular dynamics, conception, prolificacy, and fecundity in sheep

Two experiments were conducted to determine the effects of prostaglandin administration on ovarian follicular dynamics, conception, prolificacy, and fecundity in sheep. During the breeding season, multiparous Corriedale ewes were randomly allocated to two groups: 1) PG group (n = 15 and n = 135 in Experiments I and II, respectively): synchronized with two injections of DL-Cloprostenol (125 μg) given 7 d apart, and inseminated at a fixed time (Day 0), 48 h after the second injection; and 2) Control group (n = 15 and n = 73 in Experiments I and II): ewes in spontaneous estrus inseminated at detected estrus. Ewes received 100 × 10⁶ sperm by intrauterine AI. Ultrasonography was used to evaluate growth of the ovulatory follicle, ovulation rate (OR), conception rate, and prolificacy on Days 30 and 60. Ewes from the group PG had a larger (4.8 ± 0.5 mm, mean ± SEM; P < 0.05) ovulatory follicle that grew faster (1.2 ± 0.3 mm/d, P = 0.08), and a lower OR (1.37 ± 0.1, P < 0.05), compared to ewes from the Control group (3.9 ± 0.2 mm, 0.7 ± 0.2 mm/d, and 1.61 ± 0.1 respectively). Plasma progesterone concentrations from Days −6 to 1 were lower in the PG group (P < 0.05), but plasma estradiol concentrations were similar between groups (P > 0.05). Progesterone concentrations were similar between groups during the early luteal phase and on Days 12 and 17 (P > 0.05). The embryo recovery rate (Day 7) tended to be lower in the PG group (39 vs 64%, P = 0.08), but embryo quality did not differ between groups. Conception, prolificacy and fecundity, were lower in the PG than in the Control group (P < 0.05). Cumulative reproductive losses were similar between groups, but more twins were lost in the PG group (P < 0.05). We concluded that in ewes synchronized with PGF_2α given twice, 7 d apart, lower reproductive performance was associated with an environment dominated by lower progesterone concentrations that stimulated the preovulatory follicle to grow faster and become larger; this was associated with lower rates of ovulation, conception, prolificacy, and fecundity.     

Effect of granulocyte-macrophage colony-stimulating factor deficiency on ovarian follicular cell function

Granulocyte-macrophage colony-stimulating factor (GM-CSF), a cytokine secreted by lymphohaemopoietic and other cell lineages, is known to influence ovarian cyclicity and embryo development. The aim of this study was to examine the effect of GM-CSF on ovarian follicular cell function using GM-CSF-deficient (GM -/-) mice. Immature GM -/- and GM +/+ mice were stimulated with eCG, and cumulus-oocyte complexes and mural granulosa cells were collected 48 h later. Expression of GM-CSF receptor (GM-CSFR) alpha and beta mRNA subunits by cumulus-oocyte complexes and mural granulosa cells was examined using RT-PCR. Cumulus-oocyte complexes from both genotypes were found to express mRNA for the GM-CSFRalpha-subunit only, while the mural granulosa cells expressed both the alpha and beta receptor subunits. Cumulus-oocyte complexes recovered from GM -/- mice had approximately twice the number of cumulus cells per cumulus-oocyte complex than did those of GM +/+ mice (P < 0.05), even though the growth-promoting activity of denuded GM -/- oocytes was found to be equivalent to that of wild-type oocytes. GM-CSF deficiency was associated with marginally increased DNA synthesis in cumulus cells and significantly (P < 0.05) lower progesterone production by mural granulosa cells recovered from GM -/- compared with those recovered from GM +/+ mice. The addition of rec-mGM-CSF in vitro did not affect DNA synthesis in either cell type or progesterone production by mural granulosa cells, irrespective of GM-CSF status. There was no effect of GM-CSF deficiency on the capacity of FSH and insulin-like growth factor I to stimulate DNA synthesis in cumulus-oocyte complexes (approximately 15- and threefold, respectively) and in mural granulosa cells (approximately two- and threefold, respectively). Taken together, these data show that GM-CSF influences events associated with follicular maturation in mice. The effects of GM-CSF are not exerted directly in granulosa or cumulus cells, but appear to be mediated indirectly, perhaps through the agency of steroidogenesis-regulating secretions of local macrophage populations residing in the theca.     

Impact of exogenous progesterone on ovarian follicular dynamics and function in mice.

Raising progesterone concentrations in young adult mice by subcutaneous implants resulted in ovulation being blocked and the cessation of oestrous cycles. The effect of this treatment on the numbers and dynamics of preantral follicles during 36 days of treatment was studied using a compartmental model to analyse differential follicle counts. Changes in growth and/or death rates were detected at all stages of follicular development. An increased rate of growth through preantral stages was predicted in the treatment group when compared with the controls, but most of these follicles did not reach the antral stage of development as an increased death rate was observed at large preantral stages (stage IV). Antral follicles were formed in the treatment group, but all succumbed to atresia. Increased atresia in the antral population of follicles in the treatment group was observed directly.     

QTL and candidate genes for fecundity in sows

Fecundity in pigs is a trait of major economic interest but low heritability. For the improvement of fecundity, genetic markers for selection are desirable and therefore, several searches for genetic variation influencing fecundity have been performed. The aim of this review is to compare and to evaluate all published QTL analyses and candidate gene approaches concerning reproductive traits in sows. For this purpose, we present a comprehensive cytogenetic map comprising 54 QTL and 11 candidate genes with influence on reproductive traits. The evaluation and comparison of the results showed similarities, but also marked differences among studies. Reasons for different results are multicausal and are due to differences between resource populations, number of evaluated animals, mating systems, measured phenotypical traits and environmental influences. We could show that chromosome 8 and to a lower extend chromosome 7 are the most important chromosomes with regard to reproductive traits in pigs. For further research, fine mapping of the identified QTL regions is necessary in order to confirm and to narrow the most likely chromosomal intervals. Although difficult to perform, an advance would be a standardization of the experimental setup in particular, in respect to the collection of phenotypic data. Furthermore, we suggest to publish the information on further identified QTL and candidate genes as comprehensive and accurate as possible in order to allow a more transparent comparison and collation of the results.     

Effect of turmeric on the viability,ovarian folliculogenesis,fecundity, ovarian hormones and response to luteinizing hormone of rabbits

The present study investigated whether dietary turmeric (Curcuma longa L.) can improve rabbit reproduction, ovarian function, growth, or viability. Female New Zealand White rabbits were either fed a standard diet (n=15) or a diet enriched with 5 g (group E1) or 20 g (group E2) turmeric powder per 100 kg feed mixture (n=16 or 15, respectively). After 295 days, weight gain, conception and kindling rates, pup and mother viability, ovarian macro- and micro-morphometric indices, release of leptin in response to the addition LH, and the release of progesterone, testosterone and leptin by isolated ovarian fragments were analyzed. Dietary turmeric failed to affect ovarian length and weight but did increase the number of primary follicles (E2: 32.5% greater than control group), as well as the diameter of primary (E1: +19.4%, E2: +21.1%), secondary (E2: +41.4%), and tertiary (E1: +97.1%, E2: +205.1%) follicles. Turmeric also increased the number of liveborn (E1: +21.0%) and weaned (E1: +25.0%) pups and decreased the number of stillborn pups (E2: −87.5%) but did not affect weight gain, conception, or kindling rate. Furthermore, dietary turmeric decreased doe mortality during the first reproductive cycle (13.3% in control; 0% in E1; and 6.7% in E2) but not during the second cycle. In vitro, the ovaries of the turmeric-treated rabbits released more progesterone (E1: +85.7%, E2: +90.0%) and less testosterone (E2: −87.0%) and leptin (E2: −29.0%) than the ovaries of control rabbits. Moreover, LH decreased the leptin output of control rabbits but increased that of experimental rabbits. Therefore, it is likely that dietary turmeric improves pup viability and that it could promote rabbit fecundity by either (1) promoting the production of primary ovarian follicles or (2) stimulating the growth of follicles at all stages of folliculogenesis.     

Ovarian follicular activity in Booroola lambs with and without a fecundity gene

The ovaries of 3-month-old Booroola lambs which were heterozygous carriers of a major gene (F) influencing the ovulation rate in mature ewes (i.e. F + lambs) were compared to those ofsimilarly-aged Booroola lambs which were non-carriers of the F-gene (i.e. ++ lambs). The ovaries of the F + Booroola lambs were significantly lighter (P less than 0.01) than those of ++ lambs even though the mean +/- s.e.m. number of follicles (greater than or equal to 1 mm diam.) in the F + lambs was greater than that in the ++ lambs (i.e. F + lambs, 30.2 +/- 2.5 follicles; ++ lambs, 18.4 +/- 1.2 follicles; P less than 0.01). In granulosa cells from non-atretic follicles (greater than or equal to 1 mm diam.) from F + and ++ Booroola lambs, FSH (NIAMDD-FSH-S16) doses of 100 and 1000 ng/ml caused significant stepwise increases (P less than 0.05) in cyclic adenosine 3',5'-monophosphate (cAMP) production compared to that achieved at FSH doses of 0 and 1 ng/ml or at any FSH dose in cells from atretic follicles. However, no significant differences in FSH-induced cAMP production were noted with regard to Booroola genotype or follicular diameter. None of the granulosa cell preparations from non-atretic follicles of 1-2.5 mm diameter from F + lambs (N = 13) or from non-atretic follicles of 1-4.5 mm diameter from ++ lambs (N = 16) responded to LH (NIAMDD-LH-S24; 10 or 1000 ng/ml) to produce significantly more cAMP than did the controls. In contrast, the granulosa cell preparations from non-atretic follicles of 3-4.5 mm diameter from F + lambs (N = 4) and from non-atretic follicles of greater than or equal to 5 mm diameter of ++ lambs (N = 4) produced significantly more cAMP (P less than 0.05) in response to LH (1000 and/or 10 ng/ml) relative to that in the controls. The theca interna from follicles of lambs of both genotypes had functional LH receptors as judged by the androstenedione responses to exogenous LH although no genotypic differences were noted. In F + lambs, the follicular fluid concentrations of testosterone but not oestradiol (i.e. in 1-4.5 mm diam. follicles) and granulosa cell aromatase activity (i.e. in 3-3.5 mm diam. follicles) were significantly higher (both P less than 0.05) than in corresponding follicles or cells from ++ lambs. Collectively the results suggest that the Booroola F-gene influences the composition and function of sheep ovaries before puberty.     

Circadian clock genes,ovarian development and diapause

Insects, like most organisms, have an internal circadian clock that oscillates with a daily rhythmicity, and a timing mechanism that mediates seasonal events, including diapause. In research published in BMC Biology, Ikeno et al. show that downregulation of the circadian clock genes period and cycle affects expression of ovarian diapause in the insect Riptortus pedestris. They interpret these important results as support for Erwin Bünning's (1936) hypothesis that the circadian clock constitutes the basis of photoperiodism. However, their observations could also be the result of pleiotropic effects of the individual clock genes.     

Pituitary and ovarian function in postpartum beef cows. I. Effect of suckling on serum and follicular fluid hormones and follicular gonadotropin receptors

The effect of suckling on serum and follicular fluid hormones and on follicular gonadotropin receptors was studied. Sixteen anestrous postpartum cows were assigned to 1 of 2 groups: suckled (S) or weaned (W). All calves were allowed to suckle ad libitum from parturition to 21 days postpartum when calves from W cows were weaned. All cows were ovariectomized on Day 25 postpartum. W cows had more (P less than 0.01) pulses of LH during the 96-h period from weaning until ovariectomy than S cows (6.3 vs. 1.3 pulses). Serum concentrations of prolactin (Prl), estrone (E1), estradiol-17 beta (E2) and progesterone (P) were not different (P greater than 0.10) between groups. Furthermore, there were n differences (P greater than 0.10) in follicular in contents of luteinizing hormone (LH), E1, E2 and P between the treatment groups. However, follicular fluid content of Prl was greater (P less than 0.05) in the W cows than in the S cows (123 vs. 65.1 ng/cow). The number of follicular LH receptors was greater (P less than 0.05) in the W cows than in the S cows (71.1 vs. 48.3 fmoles/mg protein) although the number of follicular follicle-stimulating hormone (FSH) receptors was not different (P greater than 0.10) between W cows and S cows (1531 vs. 1862 fmoles/mg protein). There were no correlation between serum hormone concentrations and follicular fluid hormone content; however, the numbers of follicular LH receptors and follicular fluid Prl content were highly correlated in the W cows (r = 0.85; P less than 0.05). It is concluded that removal of the suckling stimulus increases pulsatile LH release and the accumulation of Prl in the follicular fluid. These factors, either together or separately, may at least in part be responsible for the increase in follicular LH receptor concentrations that were observed in the W cows.     

Regulation of the ovarian follicular vasculature

Angiogenesis is associated with follicular development and is regulated independently within each follicle potentially making the functioning of its vasculature critically important in determining its fate. This review examines the various ways in which follicular angiogenesis may be monitored, describes the follicular localisation and changes in pro- and anti-angiogenic factors that may regulate the process and how antagonists may be used to elucidate their physiological role in vivo. Thus, inhibition of vascular endothelial growth factor (VEGF), VEGF receptor-2, vascular endothelial cell cadherin or interference with the angiopoietin system can inhibit follicular development or prevent ovulation.     

Spawning season, ovarian development and fecundity of female Trichomycterus corduvense (Osteichthyes, Siluriformes)

We studied female reproductive biology of Trichomycterus corduvense. The study was carried out in the Anizacate River (Córdoba, Argentina). Samples were collected throughout one year on a monthly basis. Seven oocyte phases were identified. Five ovarian stages were described based on the macroscopic analysis of the oocyte phases. The spawning season for the species ranges from October to February; it was determined based on variations in GSI and the existence of mature females. The dynamics of oocyte development of T. corduvense, indicated the asynchronism of maturation. The correlation coefficient between fecundity and the individual weight was very low. Therefore, we suggest that this coefficient cannot be used to predict T. corduvense fecundity.     

Expression and function of HOXA genes in normal and neoplastic ovarian epithelial cells

We studied the roles of three HOXA genes in cultured normal ovarian surface epithelial (OSE) cells and ovarian cancer cells. They included HOXA4 and HOXA7 because, by cDNA microarray analysis, these were more highly expressed in invasive ovarian carcinomas than in benign or borderline (noninvasive) ovarian tumors, and HOXA9 because it characterizes normal oviductal epithelium, which resembles ovarian serous adenocarcinomas. The three HOXA genes were more highly expressed when OSE cells were dividing and motile than when they were confluent and stationary, and also when they dispersed in response to EGF treatment or to reduced calcium concentrations in culture media. The expression of the HOXA genes varied among ovarian cancer cell lines, but was highest in lines with compact epithelial morphologies. We focused on HOXA4 as the most highly expressed in the ovarian carcinoma array. HOXA4 expression did not parallel proliferative activities of either OSE or ovarian cancer lines. Moreover, modifying HOXA4 expression in ovarian cancer cell lines did not alter either E-cadherin expression or CA125 secretion. However, HOXA4 downregulation enhanced EGFR phosphorylation and migration in serum-starved OSE and ovarian cancer cells in response to EGF, and enhanced migration of all ovarian cancer lines in 5% serum even without EGF treatment. Thus, HOXA4 expression does not correlate with proliferation or with epithelial differentiation, but it increases in response to OSE cell dispersion and negatively regulates EGFR activation and the motility of OSE and of ovarian cancer cells. HOXA4 expression was highest in cancer lines with compact epithelial growth patterns, suggesting, again, an anti-dispersion function. In summary, increased HOXA4 expression in ovarian cancer appears to constitute a tumor-suppressive, homeostatic response to aberrant cell behavior, and, in particular, to cell dispersion and migration.     

Extracellular matrix in ovarian follicular development and disease

The ovarian follicle contains several different cell types and separate compartments and undergoes substantial development during its growth and maturation. Extracellular matrix (ECM) could be expected to play a major role in these processes. Most research on ECM in follicles has focused on the follicular basal lamina and its changing composition during folliculogenesis and on the specialised matrix formed at ovulation by the cumulus cells surrounding the oocyte and the zona pellucida. We review these aspects. Few naturally occurring gene mutations have identified unique roles for ECM molecules in follicular function. Presumably, any mutations leading to reduced fertility are eliminated quickly by natural selection and, when mutations are not eliminated, considerable redundancy occurs to ensure successful reproduction. In mice, in which the genome can be easily manipulated, the modification of matrix components associated with cumulus and oocytes has often resulted in partial infertility, suggesting redundancy. We provide an update of basal lamina components focusing on newer discoveries. In addition, we review matrix associated with the occyte and cumulus cells (excluding the zona pellucida) and other components of ECM. Where possible, we examine evidence for the role of the ECM in follicular development and diseases.Research in the authors' laboratories has been supported by the National Health and Medical Research Council of Australia, The University of Adelaide, Wellcome Foundation, and the Clive and Vera Ramaciotti Foundation.     

Triangular fecundity function and ageing in ladybird beetles

Abstract 1. In insects, the age schedules of fecundity tend to be triangular and this has been attributed more to temporal patterns of mortality than to fecundity. The objective of the work reported here was to test the assumption that senescence shapes the fecundity function in ladybird beetles, and in particular that the production function declines with age.
2. The results of a laboratory study on three species of predatory ladybird beetle indicated that the efficiency with which these insects acquire and process food declined with age. Although supplied with the same amount of food each day, after the onset of reproduction, these beetles ate less and less with increasing age. Egg production mirrored the decline in aphid consumption. Associated with this was a decline in fertility, assimilation, and speed of locomotion with age.
3. This study indicates that production declined with age and that this shaped the fecundity schedules in these ladybird beetles. In addition, the results indicated that ladybirds are income breeders and, as predicted, the reproductive effort of the small species was greater than that of the large species used in this study.     

Effects of fenoxycarb on ovarian development, spring fecundity and longevity in winterform pear psylla

The insect growth regulator fenoxycarb prompts ovarian development in diapausing winterform pear psylla, Cacopsylla pyricola (Förster) (Homoptera: Psyllidae). We applied fenoxycarb to caged psylla in September, November, and December to test whether premature ovarian development reduced overwintering survival, spring fecundity, or spring longevity. Fenoxycarb prompted ovarian development in all treated psylla, with the largest effects occurring in the September-treated insects. Recovery of live psylla in spring was 46–95% in treated insects and 72–92% in controls; overwintered insects from the fenoxycarb treatment survived field temperatures below –20°C despite having had mature ovaries. Fecundity and longevity of psylla were the same in treated and untreated insects, indicating that overwintering with mature ovaries did not cause reduced spring egglaying capacity. Several treated insects each deposited over 1900 eggs and survived more than 120 days. Due to their more advanced development, treated insects had higher oviposition rates than controls during the first 5 days after removal from the field. The largest impact on spring fitness was due to the effects of fenoxycarb on egg hatch. Eggs deposited on clean foliage by September-treated females were less likely to hatch than eggs deposited by controls, suggesting that fenoxycarb affected developing eggs within the female. Prospects for using fenoxycarb in fall to control pear psylla appear to be limited.     

Fungal apoptosis: function, genes and gene function

Cells of all living organisms are programmed to self-destruct under certain conditions. The most well known form of programmed cell death is apoptosis, which is essential for proper development in higher eukaryotes. In fungi, apoptotic-like cell death occurs naturally during aging and reproduction, and can be induced by environmental stresses and exposure to toxic metabolites. The core apoptotic machinery in fungi is similar to that in mammals, but the apoptotic network is less complex and of more ancient origin. Only some of the mammalian apoptosis-regulating proteins have fungal homologs, and the number of protein families is drastically reduced. Expression in fungi of animal proteins that do not have fungal homologs often affects apoptosis, suggesting functional conservation of these components despite the absence of protein-sequence similarity. Functional analysis of Saccharomyces cerevisiae apoptotic genes, and more recently of those in some filamentous species, has revealed partial conservation, along with substantial differences in function and mode of action between fungal and human proteins. It has been suggested that apoptotic proteins might be suitable targets for novel antifungal treatments. However, implementation of this approach requires a better understanding of fungal apoptotic networks and identification of the key proteins regulating apoptotic-like cell death in fungi.