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PubMedDate not supplied

Two AGAMOUS-like MADS-box genes from Taihangia rupestris (Rosaceae) reveal independent trajectories in the evolution of class C and class D floral homeotic functions.

Duplicate genes may be retained by sub- and/or neofunctionalization through changes in gene expression and/or coding sequence, and therefore have the potential to contribute to the genetic robustness and diversification of an organism. In this study, two MADS-box genes were isolated from Taihangia rupestris, a core eudicot species belonging to the Rosaceae. Sequence and phylogenetic analyses revealed that they are clade members of the euAG and PLE lineages, respectively, and hence the two genes are named TrAG (Taihangia rupestris AGAMOUS) and TrSHP (Taihangia rupestris SHATTERPROOF). Southern blot analysis shows that TrSHP is a single-copy gene in the T. rupestris genome. In situ hybridization analyses show that both TrAG and TrSHP are mainly expressed in the stamens, carpels, and ovules. When the stamen primordia are firstly observed, TrAG is initially expressed in the floral meristem domain that will initiate stamens and carpels. In contrast, no TrSHP signal is observed at this developmental stage. At late stages of carpel development, TrAG expression is detected in the ovules, ovaries, and developing styles and stigmas, whereas TrSHP expression is tightly restricted to the ovules. The transgenic Arabidopsis plants containing 35S::TrAG and 35S::TrSHP, respectively, showed similar phenotypes, including homeotic conversions of sepals into carpelloid structures bearing ovules and petals into staminoid organs, and the fruits shattering prematurely along the dehiscence zone. In addition, the phenotype of the transgenic 35S::TrSHP Arabidopsis plants revealed that perianth abscission was inhibited. Yeast two-hybrid assays indicated that TrAG can interact with TrSEP3, whereas TrSHP cannot. The data suggest that the euAG and PLE paralogs, TrAG and TrSHP, may have subfunctionalized and/or neofunctionalized through changes in expression patterns and accumulating variations in the coding regions. Taking these findings together with those available expression and functional data from Arabidopsis and other species, we conclude that the compensatory ways vary among the euAG and PLE lineage pairs in eudicot species.

Blotting, Southern↗
PubMed1992

Plasma and follicular tissue steroid levels in the elasmobranch fish, Torpedo marmorata.

Steroid concentrations in plasma and follicular tissues (theca plus granulosa layers) were determined by radioimmunoassay in the aplacental viviparous ray, Torpedo marmorata, during various stages of the reproductive cycle. Steroids in the uterine fluid of pregnant animals and in preovulatory atretic follicles were also measured. In the follicular tissue of cyclic animals, levels of progesterone were always lower than those of estradiol-17 beta and androgens (testosterone plus 5 alpha-dihydrotestosterone). Estradiol-17 beta and androgen levels increased as the animals approached the ultimate maturational stage before ovulation. Androgens were not detectable in plasma, while estradiol-17 beta increased dramatically before ovulation. In pregnant animals, only small ovarian follicles (less than 5 mm in diameter) were observed, and these had hormone concentrations that were similar to those of the small follicles of cyclic animals. Progesterone was the only steroid detected in the uterine fluid of pregnant animals. In completely sclerotic atretic follicles of pregnant animals, steroids were not detected. Progesterone was the main hormone in atretic follicles undergoing yolk resorption. This suggests that the latter may contribute to the elevated plasma progesterone concentrations of pregnant animals.

Animals↗
PubMed1988

Major genes control hormone-induced ovulation rate in mice.

The present study examined the magnitude of genetic variation, mode of inheritance and number of loci controlling major genetic differences in hormone-induced ovulation rate in mice. Mice were injected with 5 i.u. PMSG at 28 days of age and 5 i.u. hCG at 30 days, and hormone-induced ovulation rate was determined from counts of oviducal eggs in cumulus the next morning. Six-fold genetic differences in induced ovulation rate were detected amongst strains, ranging from a low mean (+/- s.e.) value of 8.8 (+/- 0.9) in A/J up to 53.5 (+/- 2.2) in C57BL/6J. The number of ova differed significantly amongst strains and amongst F1 crosses (P less than 0.0001): 70% of the variation in hormone-induced ovulation rate was amongst strains. Of 9 F1 crosses examined, 4 showed positive heterosis, 3 showed no heterosis and 2 showed negative heterosis for hormone-induced ovulation rate. Analysis of parental, F1 and F2 generations revealed that the induced ovulation rate of A/J and C57BL/6J mice differed due to the action of about 3 or 4 loci, and A.SW/SnJ and SJL/J mice differed due to the action of about 2 to 3 loci. Analysis of recombinant inbred strains formed from A/J and C57BL/6J confirmed that these strains differed due to the action of a small number of loci. This study demonstrates the existence of a small number of major genes controlling hormone-induced ovulation rate in young mice.

Animals↗
PubMed1999

Characterization of immunoglobulins and cytokines in human cervical mucus: influence of exogenous and endogenous hormones.

Mucosal immunity in the female reproductive tract is influenced by immunoglobulins (Igs), cytokines, and reproductive hormones. Previous studies of reproductive-aged women demonstrated that IgA and IgG increases in cervical mucus corresponded to elevated levels of IL-1beta which occurred 1 day before the peak of endogenous estradiol production prior to ovulation. We sought to determine the effect of exogenous hormones on reproductive tract immunity in women on oral contraceptive pills (OCPs) and to compare the results with respect to naturally cycling women. Twelve women of reproductive age who had negative cervical cultures, a normal pap smear, and agreed to abstain from sexual intercourse during the study initiated OCPs. Cervical mucus and vaginal washes were collected at six intervals (2-3 days apart) throughout the treatment cycle. Fifteen naturally cycling women had similar samples collected prior to, during, and subsequent to ovulation. Cervical mucus samples were assayed for IgA, IgG, IL-1beta, IL-6, and IL-10 by enzyme-linked immunosorbent assay (ELISA). IgA, IgG and IL-1beta levels in women on OCPs paralleled increasing levels of norethindrone. Mean values of IgA increased from a low of 14.4+/-3.1 to 41.1+/-9.4 mg/dl and decreased significantly after the cessation of the pills (P < 0.001). In naturally cycling women, the largest quantities of Igs were detected prior to ovulation. By comparison, mean values of IgA in the cervical mucus of women on OCPs (24.4 mg/dl) exceeded peak levels of IgA in the cervical mucus of naturally cycling women (14.6 mg/dl). IgA was the predominant Ig detected in cervical mucus of women on OCPs. Both immunoglobulins in each group exhibited changes relative to their hormonal status. The increased levels of IgA in the cervical mucus of women on OCPs may explain the clinical observation of a lower incidence of sexually transmitted diseases.

Adult↗
PubMed1995

Ultrasound-guided intrafollicular treatment in mares.

A technique for intrafollicular treatment with a transvaginal ultrasound-guided injection needle was developed using equine chorionic gonadotropin (eCG) as the test substance. An injection was made into one growing follicle of a wave when the follicles were 20 to 23 mm. The treated follicles were injected with 1000 iu of eCG in 0.2 ml saline solution and control follicles were injected with 0.2 ml of the saline vehicle (10 mares per group, 1 follicle per mare). The injection system used an inner 25-gauge needle and an outer 20-gauge needle inserted together through the needle-guide channel of a linear-array trans vaginal transducer. The outer needle was pushed through the vaginal wall and the inner needle was then advanced into the follicle during monitoring on the ultrasound screen. The turbulence in the follicular fluid associated with injection was observable on the screen. Seven follicles were successfully injected in each group. The follicular fluid in the control follicles remained anechoic until the follicle was no longer identifiable or ovulated. All 7 follicles in the eCG group showed ultrasonic indications of luteinization, based on the formation of an echogenic, thickened wall or area. Five of the 7 developed a central area that had the ultrasonic appearance of a blood clot similar to the appearance of a corpus hemorrhagicum. Ovulation was not detected in any of the eCG-treated follicles. The maximum post-treatment diameter of follicles was greater (P < 0.05) for the eCG group (32.7 +/- 3.8 mm) than for the control group (23.4 +/- 1.8 mm). The mean diameter for the first 5 days post-treatment (before the occurrence of an ovulation in any mare) was also greater (P < 0.002) in the eCG group (21.6 +/- 0.8 mm vs 19.6 +/- 0.8 mm). Results indicated that this novel research approach is practical and has potential for studies on folliculogenesis. The technique provides a research model between the extremes of an in vitro culture system and treatment of the whole animal.

Journal Article↗
PubMed1994

Abortion and subsequent excretion of chlamydiae from the reproductive tract of sheep during estrus.

Chlamydia psittaci serovar 1 infection in pregnant sheep typically causes abortion or the birth of weak lambs. Eight sheep that experienced chlamydia-induced abortion during their first pregnancy were successfully rebred yearly for the past 2 years. Chlamydia-specific lipopolysaccharide was detectable for approximately 3 weeks in vaginal swabs taken from the experimentally infected sheep following abortion. There was no evidence of chlamydiae in vaginal, placental, or neonatal samples obtained immediately after each subsequent successful pregnancy. Sera collected from the experimentally infected sheep had persistent, high antibody levels to C. psittaci, suggesting continued exposure of the immune system to the organism. Examination of vaginal specimens obtained during various stages of the estrus cycle revealed detectable levels of chlamydiae only when the animal was near ovulation. Chlamydiae were not detected in swabs from sheep that did not experience abortion. Enhanced chlamydial excretion during the periovulation period of sheep may provide sufficient stimulation of the immune system to account for the persistent antibody response. Furthermore, the association between estrus and chlamydial shedding has important implications for transmission of infection to other ewes during breeding.

Abortion, Veterinary↗
PubMed2004

Effect of ploidy and parental genome composition on expression of Oct-4 protein in mouse embryos.

The transcription factor Oct-4 is expressed in germ cells and also is considered as a marker for pluripotency of stem cells. We first examined dynamics of Oct-4 protein expression during preimplantation development using both Western blot analysis, and immunofluorescence staining. We show that intact Oct-4 protein is not detected in either ovulated mature oocytes, or in zygotes and 2-4-cell embryos, which are the only known totipotent cell types in mammals. This finding is unexpected, since Oct-4 has been proposed to play a role in the control of totipotency. The results suggest that Oct-4 is not indispensable for fertilization and early cleavage. Rather, expression of Oct-4 protein is first detected in the nuclei of 8-16 cell morula, increases in early blastocysts, and declines in late blastocysts, in which most Oct-4 protein is confined to the inner cell mass (ICM) region, consistent with previous findings. We further compared Oct-4 protein expression in diploid and tetraploid blastocysts derived from normal fertilization or parthenogenesis, as well as expression in diploid androgenetic blastocysts. Expression levels and localization of Oct-4 protein are similar in both diploid and tetraploid early blastocysts, regardless of whether blastocysts are derived from fertilization or parthenogenesis. Androgenetic diploid blastocysts also express similar levels of Oct-4. Late blastocysts generated by both fertilization and parthenogenesis show a similar pattern of Oct-4 expression, suggesting that paternal genome activation is not required for Oct-4 expression. Expression of Oct-4 protein does not differ between diploid and tetraploid embryos, indicating that tetraploidy does not influence Oct-4 expression. Thus, expression of Oct-4 protein is initiated at morula stage in preimplantation embryos and completely controlled by a mechanism activated in oocytes. Downregulation of Oct-4 expression coincides with differentiation of trophectoderm. Similar profiles of Oct-4 expression observed in embryos with different ploidy and genome composition, are suggestive of Oct-4 being necessary but not sufficient for developmental potency.

Animals↗
PubMed1996

The effects of lactation on the fertility of dairy cows.

Lactation has been negatively associated with fertility because pregnancy rates in maiden heifers exceed those obtained after first or subsequent calvings. The extent of this difference is less in pasture-fed dairy cows ( < 10%) than in American Holsteins ( > 20%) fed grain and conserved forages. The latter cows have pregnancy rates to first insemination and oestrus detection rates of only 40 to 45%. This suggests that the subsequent fertility of inherently fertile Holstein heifers may be severely compromised by high levels of milk production. International comparisons show that pasture-fed dairy cows may experience extended periods of anovulatory anoestrum but have normal fertility (60% pregnancy rate to first insemination) once cycling. The high-producing American Holstein may ovulate within 4 weeks postpartum but is more likely to continue ovulating without being detected in oestrus. Both situations are associated with negative energy balances (NEB) during early lactation. The severity and duration of this NEB may vary with body condition at calving, age or parity, ration formulation, production level and environmental factors. Relative daily milk yield is not an absolute indicator of NEB, because some lower producing cows within a herd have lower feed intakes and more severe energy deficits. NEB is not simple to measure; nonetheless, it is correlated with genetic improvement for milk yield. A positive energy balance, greater weight gain and higher body condition score have all been shown to be positively correlated with plasma progesterone concentrations in early lactation. No studies have investigated the possibility that the rapid increase in metabolic rate at this time may also alter steroid concentrations with consequent effects on oestrous behaviour and fertility. Studies to more precisely define the effects of increasing milk yields in early lactation, especially in Holsteins, may need to be completed in Australia and New Zealand. Oestrus detection rates and pregnancy rates for American Holsteins of less than 50% are accepted widely in the USA. Such low detection rates confound studies on fertility. The objective should be to increase these 2 rates to at least 80% and 60% respectively. This may involve the use of controlled breeding, especially if oestrous behaviour is less overt in high-producing Holstein cows.

Animals↗
PubMed1983

[Results of treatment of functional sterility with clomifen].

Our experiences in the treatment of functional sterility in 482 patients with clomiphene are reported. The dosage of clomiphene was 100 mg per day for 5 days. If treatment was without success after 3 cycles dosage was changed to 150 mg per day for 7 days. The ovulation induction rate detected by basal body temperature was 74.5%. Conceptions were obtained in 35.7%. Pregnancy was terminated by spontaneous abortion in 18.8%. In high weight patients there was the best success rate with clomiphene treatment.

Adult↗
PubMed1991

Hemorrhagic ovarian follicles in llamas.

The ovaries of 74 llamas were examined daily by transrectal ultrasonography for at least 30 d. Hemorrhagic follicles were observed in 13 (18%) llamas (incidence per anovulatory dominant follicle, 16%). The proportion of llamas in which a hemorrhagic follicle was detected was different among groups (nonmated, 8/25; mated to a vasectomized male, 4/21; mated to an intact male, nonpregnant, 1/10; mated to an intact male, pregnant, 0/18; P<0.05). A hemorrhagic follicle, observed grossly after ovariectomy, was large (13 mm) and fluctuant, with a thin translucent wall and dark red contents. No ovulatory stigma was detected, and after incising the wall, bloody fluid escaped and the follicle collapsed leaving only a small blood clot within the antrum. Ultrasonically, the formation of a hemorrhagic follicle was indicated by scattered free-floating echogenic spots within the follicular antrum which swirled upon ballottement of the ovary. The antral contents appeared to become organized (did not swirl when ballotted) after follicle growth ceased. Ultrasonic indications of antral hemorrhage were not observed in any follicles in which ovulation was later detected (0/45 ovulatory follicles). All of the hemorrhagic follicles (13/13) involved the dominant follicle of a wave during which no copulatory stimulus was applied. Hemorrhagic follicles were apparently anovulatory and were repeatable (P<0.05) within individuals. The interval from first detection to the first day of maximum diameter was longer (P<0.05) and maximum diameter was greater (P<0.0001) for hemorrhagic follicles than nonhemorrhagic follicles (16.4 versus 13.1 d and 22.1 versus 12.8 mm, respectively); however, the interwave interval was not affected by the presence of a hemorrhagic follicle. Luteinization of the hemorrhagic follicle was indicated (thickened wall) in two llamas by an elevated plasma progesterone concentration and/or by ultrasound. By their large size, hemorrhagic follicles may be interpreted as hemorrhagic follicular cysts; however, they were not associated with other ovarian irregularities or with infertility.

Journal Article↗
PubMed2002

A. thaliana TRANSPARENT TESTA 1 is involved in seed coat development and defines the WIP subfamily of plant zinc finger proteins.

Seeds of the Arabidopsis thaliana transparent testa 1 mutant (tt1) appear yellow, due to the lack of condensed tannin pigments in the seed coat. The TT1 gene was isolated by reverse genetics using an En-1 transposon mutagenized A. thaliana population. TT1 gene expression was detected in developing ovules and young seeds only, and the gene was shown to encode a nuclear protein. Mutant seeds displayed altered morphology of the seed endothelium in which brown tannin pigments accumulate in wild-type plants, indicating that TT1 is involved in the differentiation of this cell layer. When overexpressed in transgenic A. thaliana plants, TT1 caused aberrant development and organ morphology. The protein contains a novel combination of two TFIIIA-type zinc finger motifs. Closely related motifs were detected in a number of putative proteins deduced from plant genomic and EST sequences. The new protein domain containing this type of zinc finger motifs was designated WIP, according to three strictly conserved amino acid residues. Our data indicate the existence of a small gene family in A. thaliana which is defined by the occurrence of the WIP domain. WIP genes may play important roles in regulating developmental processes, including the control of endothelium differentiation.

Amino Acid Sequence↗
PubMed1990

Predicting pregnancy outcome by the observation of a gestational sac or of early fetal cardiac motion with transvaginal ultrasonography.

Transvaginal ultrasound (US) allows for observation of the gestational sac and cardiac motion as early as 3 and 4 weeks after ovulation, respectively. The purpose of this study was to determine how well the first observation of cardiac motion, using weekly transvaginal US examinations, predicted pregnancy outcome. Three hundred sixteen pregnancies wherein the date of ovulation was known and a single gestational sac was visualized at 3 weeks after ovulation were studied. Cardiac motion was first detected at 4 weeks after ovulation in 226 (71.5%), and at 5 weeks in 67 (21.2%). In 23 patients, cardiac motion was never observed. In those patients with cardiac motion visible at 4 weeks after ovulation, 94.2% have subsequently delivered viable infants. This contrasts with only 70.1% for those patients who first had observable cardiac motion 1 week later (P = 6.7 X 10(-6]. This study demonstrates that the solo finding of a gestational sac is a poor predictor of pregnancy outcome (82.3% accurate) and that the earlier that cardiac motion is initially observed, the better the pregnancy prognosis.

Abortion, Spontaneous↗
PubMed2000

A S100 homologue mRNA isolated by differential display PCR is down-regulated in the brook trout (Salvelinus fontinalis) post-ovulatory ovary.

A down-regulated cDNA fragment was isolated using differential display PCR between ovulatory and post-ovulatory brook trout ovarian tissue. Using this cDNA as a probe, a full-length cDNA of 538bp was obtained by screening an ovarian cDNA library. The cDNA isolated presumably encodes for a 101 amino acid protein that is similar in sequence to a group of calcium binding proteins called S100 proteins. Within the S100 family, the differentially expressed trout protein is more similar to S100 A1 and A10 proteins. A comparison of the trout S100 protein with mammalian S100 A1 proteins and a S100 protein previously isolated from the loach suggests that the trout S100 protein could be a new member of the S100 family. On Northern blots of ovarian tissue, the trout S100 cDNA hybridized with a 550bp transcript which appeared to progressively decrease throughout ovulation and was significantly down-regulated by 48h post-ovulation. A transcript was also detected in several other tissues such as the heart, skin, spleen, gills, intestine, stomach and testis. Using in situ hybridization the trout S100 mRNA was strongly detected in the granulosa cells of the ovulated follicle. These results suggest that a member of the S100 protein family may play a role in the trout ovary during the periovulatory period.

Amino Acid Sequence↗
PubMed1997

Superovulatory response following ablation-induced follicular wave emergence at random stages of the oestrous cycle in cattle.

Based on the premise that superovulation in cattle is optimal when superstimulation is initiated at the time of follicular wave emergence, the present study was done in beef heifers to determine if the superovulatory response following a single bolus of gonadotrophin treatment after follicle ablation (induced wave) at random stages of the oestrous cycle is comparable to the same gonadotrophin treatment at mid-dioestrus (spontaneous wave). In Experiment 1, heifers were assigned to nonablation (n = 18) and ablation (n = 20) groups. In nonablated heifers, superstimulatory treatment was given as a single subcutaneous injection (Folltropin-V, 400 mg) at mid-di-oestrus to coincide with emergence of the spontaneous follicular wave 8 to 12 days after oestrus. In ablated heifers, the same superstimulatory treatment was given 1 day after ablation of all follicles > or = 5 mm at random stages of the oestrous cycle to coincide with emergence of the ablation-induced wave. In both the nonablation and ablation groups, PGF2 alpha (Estrumate, 500 micrograms) was given 48 h after the superstimulatory treatment and artificial insemination was done 60 and 72 h later. Reproductive tracts were collected at the time of slaughter 6 or 7 days after insemination. Observations made in Experiment 1, indicated that some ablated heifers had only partial luteal regression at the time of insemination, while some others exhibited behavioral oestrus as early as 24 h after PGF2 alpha treatment. The design was amended in Experiment 2 to address these problems. Heifers were assigned to nonablation (n = 17), ablation-alone (n = 20) or ablation plus progestogen (n = 20) groups. Follicle ablation, superstimulatory treatment, artificial insemination and collection of reproductive tracts were done as in Experiment 1. However, all heifers were given two doses of PGF2 alpha (500 micrograms/dose) 48 and 60 h after superstimulatory treatment to ensure complete luteal regression, and heifers in the ablation plus progestogen group received a norgestomet ear implant at the time of follicle ablation to prevent early ovulations. The implant was removed at the time of the second PGF2 alpha treatment. In Experiments 1 and 2, the means for the ovarian and superovulatory responses were not significantly different between groups. Averaged over the nonablation and all ablation groups for Experiments 1 and 2, the mean number. of corpora lutea, fertilized ova and transferable embryos were 22.9 vs 18.6, 7.3 vs 7.8 and 5.4 vs 5.6, respectively. In summary, follicle ablation at random stages of the oestrous cycle followed by a single bolus of gonadotrophin treatment 1 day later resulted in a superovulatory response that was comparable to the same superstimulatory treatment administered around the time of spontaneous wave emergence at mid-dioestrus. The ablation/superstimulation method described herein offers the advantage of initiating superstimulatory treatment forthwith and assuring that treatment is concomitant with wave emergence to achieve an optimal superovulatory response. Moreover, the full extent of the oestrous cycle is available for superstimulation and the need for detecting oestrus or ovulation and waiting 8 to 12 days to initiate treatment is eliminated.

Animals↗
PubMedDate not supplied

Evaluation of the subfertile couple: the fine points.

The basic fertility evaluation depends more on the history than findings at the initial visit. The previous reproductive history of both partners, the duration of infertility in this union, frequency of coitus, and a complete menstrual history often point to the diagnosis and correct therapy. Previous medical records pertaining to the problem are another source of information, and recent studies such as semen analysis results, ultrasound and salpingographic reports should be sought; the actual films are preferable to the reports. Previous surgeries, thought to be unrelated to fertility, may have been performed--try to get the operative report. There are myriad drugs that can interfere with fertility in either gender; therefore, a thorough history of past and present use as well as environmental toxin exposure is necessary. Often the routine prenatal tests for titers against common viral illnesses which can cause fetal damage have not been performed. Specific ethnic groups will need special testing. No invasive test or therapy should be performed on the female partner in the absence of a recent semen analysis. Ovulation evaluation can take the form of a basal body temperature chart; it's free, doesn't hurt, and is accurate in detecting the presence of ovulation, except for the exact timing. The over-the-counter urinary LH detection kits are highly reliable in predicting the actual day of ovulation. Serial ultrasounds to do this are not cost effective. This paper will discuss these points and the commonly performed evaluations such as salpingography and endoscopy. Specific hormonal evaluations of the amenorrheic patient and those with suspected polycystic ovarian syndrome will also be discussed.

Female↗
PubMed2006

Ovarian stimulation with GnRH agonist, but not GnRH antagonist, partially restores the expression of endometrial integrin beta3 and leukaemia-inhibitory factor and improves uterine receptivity in mice.

BACKGROUND: The impact of different ovarian stimulation (OS) protocols on endometrial receptivity remains controversial. In this study, the effects of different OS on the expression of endometrial integrin beta3 subunit and leukaemia-inhibitory factor (LIF) during the implantation window and the implantation rate in mice were investigated. METHODS: Three OS protocols were used, involving either pregnant mare's serum gonadotrophin (PMSG) alone, PMSG plus GnRH agonist or PMSG plus GnRH antagonist. Uterus samples were collected at 48 h after OS or ovulation and were detected with immunohistochemistry, Western blot and RT-PCR analyses. Normal embryos at gestation day 4 were transferred into the uteri of mice in the control and OS groups. RESULTS: All OS groups showed a significant decrease in the expression of both the endometrial integrin beta3 subunit and LIF during the implantation window and the implantation rate. Among the three OS groups, GnRH agonist-treated mice showed a higher endometrial integrin beta3 subunit and LIF expression and a higher implantation rate. No significant difference was found in the measured indices between the GnRH antagonist and PMSG groups. CONCLUSIONS: OS may inhibit the expression of endometrial integrin beta3 subunit and LIF and impair endometrial receptivity in mice. OS with GnRH agonist, but not GnRH antagonist, may partially restore the endometrial physiological secretion and improve uterine receptivity.

Animals↗
PubMed2002

Reproductive responses of early postpartum dairy cattle to continuous treatment with a GnRH agonist (deslorelin) for 28 days to delay the resumption of ovulation.

An experiment was conducted to investigate the potential of chronic delivery of a potent GnRH agonist (deslorelin) via subcutaneous implants to delay the resumption of ovulatory cycles in postpartum dairy cattle. Cows received either a single deslorelin implant (n=40; DES) within 7 days of calving or were untreated (n=24; CON). Blood samples were collected thrice weekly during the period the implants were in place. Plasma concentrations of progesterone (P4) and 17beta-oestradiol (E2) were measured along with selected serum metabolites. Implants were removed after 28 days and cattle monitored daily for behavioral oestrus. Serial weekly blood samples were collected to detect the occurrence of ovulation. Cows were artificially inseminated as they were detected in oestrus from 30 days after implant removal. Pregnancy status was subsequently determined by manual palpation of uterine contents at strategic intervals. Insertion of implants induced ovulation in 3/40 cows as determined by a rise in progesterone 7 days later. Deslorelin implants delayed the onset of ovulatory cycles compared with untreated herdmates (mean 43.4+/-4.2 versus 57.3+/-1.6 days postpartum; P<0.001). A noticeable delay of at least 12 days was observed between implant removal and the first animals ovulating. Mean plasma E2 concentrations during the period the implants were in place were similar for DES and CON cows that experienced a prolonged spontaneous postpartum anoestrus (low P4 >60 days), although both groups had concentrations only 20% of CON cows that had ovulated prior to 30 days postpartum. The patterns of recovery following implant removal were highly variable. A number of DES cows showed a low and transient rise in plasma progesterone around 21 days after implant removal. Some cows displayed oestrus but did not appear to form a fully functional corpus luteum with this phenomenon being more prevalent among DES cows (7 of 37 versus 1 of 21; P<0.05). Overall, significantly more DES cows were detected in oestrus without ovulating compared to CON cows. Final pregnancy rates did not differ between DES and CON groups. The mean time to conception for DES cows was longer (21.2+/-5.6 versus 41.1+/-7.4 days, CON versus DES; P<0.01). This difference was not present if the time from first ovulation to conception was compared (50.5+/-5.3 versus 43.5+/-9.3 days, CON versus DES; P>0.05). Deslorelin implants provided a reliable method of inducing anoestrus when treatment was initiated prior to 3 days postpartum. A variable pattern of recovery was observed which delayed conception but did not ultimately reduce the final proportion pregnant at the completion of mating. The study demonstrates the potential of GnRH agonists to control postpartum reproductive function to manipulate the fertility of dairy cows.

Animals↗
PubMed1991

Zygotic expression of the connexin43 gene supplies subunits for gap junction assembly during mouse preimplantation development.

De novo assembly of gap junctions begins during compaction in the eight-cell stage of mouse development, and intercellular coupling mediated by gap junctions appears to be required for maintenance of the compacted state. We have begun to explore the expression of the family of genes encoding the connexins, the proteins that form the gap junction channels. We recently reported that a protein with antigenic and size similarity with connexin32, the rat liver gap junction protein, is inherited as an oogenetic product by the mouse zygote, but its gene appears not to be transcribed prior to implantation (Barron et al., Dev Genet 10:318-323, 1989). Here we report that another member of this gene family, connexin43, is transcribed by the embryonic genome from shortly after the time of genomic activation. As revealed by Northern blotting, connexin43 mRNA is absent from ovulated oocytes, becomes detectable in the 4-cell stage, and accumulates steadily thereafter to reach a maximum in blastocysts. In contrast, no transcripts of connexin26 could be detected in any preimplantation stage. A protein with antigenic and size similarity with connexin43 from rat heart was found by Western blotting to accumulate from the four-cell stage onward. Immunofluorescence analysis with embryo whole mounts was used to demonstrate that this protein is incorporated into punctate interblastomeric foci during compaction, consistent with its assembly into gap junction plaques. We conclude that connexin43 is one member of the connexin gene family whose zygotic expression is critical for preimplantation morphogenesis.

Animals↗