Differences in ovarian aging patterns between races are associated with ovarian genotypes and sub-genotypes of the FMR1 gene

ABSTRACT: BACKGROUND: Ovarian aging patterns differ between races, and appear to affect fertility treatment outcomes. What causes these differences is, however, unknown. Variations in ovarian aging patterns have recently been associated with specific ovarian genotypes and sub-genotypes of the FMR1 gene. We, therefore, attempted to determine differences in how functional ovarian reserve (FOR) changes with advancing age between races, and whether changes are associated with differences in distribution of ovarian genotypes and sub-genotypes of the FMR1 gene. METHODS: We determined in association with in vitro fertilization (IVF) FOR in 62 young Caucasian, African and Asian oocyte donors and 536 older infertility patients of all three races, based on follicle stimulating hormone (FSH), anti-Mullerian hormone (AMH) and oocyte yields, and investigated whether differences between races are associated with differences in distribution of FMR1 genotypes and sub-genotypes. RESULTS: Changes in distribution of mean FSH, AMH and oocyte yields between young donors and older infertility patients were significant (all P < 0.001). Donors did not demonstrate significant differences between races in AMH and FSH but demonstrated significant differences in oocyte yields [F(2,59) = 4.22, P = 0.019]: Specifically, African donors demonstrated larger oocyte yields than Caucasians (P = 0.008) and Asians (P = 0.022). In patients, AMH levels differed significantly between races [F (2,533) = 4.25, P = 0.015]. Holm-Sidak post-hoc comparisons demonstrated that Caucasians demonstrated lower AMH in comparison to Asians (P = 0.007). Percentages of FMR1 genotypes and sub-genotypes in patients varied significantly between races, with Asians demonstrating fewer het-norm/low sub-genotypes than Caucasians and Africans (P = 0.012). CONCLUSION: FOR changes in different races at different rates, and appears to parallel ovarian FMR1 genotypes and sub-genotype distributions. Differences in ovarian aging between races may, therefore, be FMR1-associated.     

Mcl-1 is a key regulator of the ovarian reserve

A majority of ovarian follicles are lost to natural death, but the disruption of factors involved in maintenance of the oocyte pool results in a further untimely follicular depletion known as premature ovarian failure. The anti-apoptotic B-cell lymphoma 2 (Bcl-2) family member myeloid cell leukemia-1 (MCL-1) has a pro-survival role in various cell types; however, its contribution to oocyte survival is unconfirmed. We present a phenotypic characterization of oocytes deficient in Mcl-1, and establish its role in maintenance of the primordial follicle (PMF) pool, growing oocyte survival and oocyte quality. Mcl-1 depletion resulted in the premature exhaustion of the ovarian reserve, characterized by early PMF loss because of activation of apoptosis. The increasingly diminished surviving cohort of growing oocytes displayed elevated markers of autophagy and mitochondrial dysfunction. Mcl-1-deficient ovulated oocytes demonstrated an increased susceptibility to cellular fragmentation with activation of the apoptotic cascade. Concomitant deletion of the pro-apoptotic Bcl-2 member Bcl-2-associated X protein (Bax) rescued the PMF phenotype and ovulated oocyte death, but did not prevent the mitochondrial dysfunction associated with Mcl-1 deficiency and could not rescue long-term breeding performance. We thus recognize MCL-1 as the essential survival factor required for conservation of the postnatal PMF pool, growing follicle survival and effective oocyte mitochondrial function.Estimates of the human primordial follicle (PMF) reservoir, the size of which dictates the extent of the ovarian reserve, indicates the presence of at least half a million oocytes per ovary at birth.^{1, 2} The essential decision that PMFs face is either long-term arrest with a possibility of recruitment toward the growing pool, or death. Even upon recruitment to the growing pool, intricately orchestrated crosstalk of survival signals between ovarian somatic cells and oocytes facilitate the ovulation of a single oocyte in human in each cycle. Hence, the default fate for millions of ovarian germ cells is death, as only a small fraction survive till ovulation.³ Insufficient endowment during fetal development or excessive oocyte loss during postnatal life further limits the ovarian reserve and can result in an untimely exhaustion of the follicle pool leading to premature ovarian failure (POF); a syndrome that affects around 1% of all women, with a higher prevalence (up to 30%) in families with heritable traits of this condition.^{4, 5} Mechanisms responsible for maintenance of the follicular reserve are poorly understood, however, biological assessments and mathematical modeling reveal that progressive loss of follicles with age is non-linear and accelerates, especially after 38 years.^{6, 7} With a declining ovarian reserve, poor oocyte quality is an additional factor that contributes to the reduced fertility associated with increased maternal age. Oocytes and resulting embryos of older mothers have increased rates of aneuploidies likely due to defects in chromosomal cohesion and meiotic spindle stability, decreased DNA repair capacity, altered gene expression, impaired mitochondrial function and elevated cellular redox, all contributing to increased rates of cell death.^{8, 9, 10}The marked decline of oocyte number in mammalian ovaries has been attributed to oocyte loss via stage-specific modes of death. As yet, perinatal PMF loss in mice most frequently engages apoptotic cell death,^{11, 12} whereas within the postnatal ovary, oocytes in growing follicles undergo atresia, a less ''molecularly'' defined death, carrying hallmarks of both apoptosis and autophagy.^{13, 14, 15} It is thus surprising that no member of the anti-apoptotic B-cell lymphoma 2 (Bcl-2) family has been identified with a definitive role in governing oocyte survival and the maintenance of the ovarian reserve. Bcl-2l2/Bcl-w and Bcl-2-l10/Diva deficiency had no apparent impact on the ovarian reserve, and although ablation of Bcl-2 led to a loss of one-third of the adult PMF pool, the growing follicle pool was not significantly impacted and these animals did not undergo POF.^{16, 17, 18, 19} Conditional Bcl-x (Bcl-2l1) inactivation led to increased primordial germ cell apoptosis in the embryo,²⁰ but postnatal inactivation of Bcl-x in oocytes did not compromise the ovarian reserve in young females.²¹ Bcl2a1a/Bfl-1/A1 was low to undetectable in fully grown germinal vesicle (GV) or ovulated murine oocytes,²² however, the impact of Bfl-1 deficiency on the ovarian reserve has not yet been analyzed to the best of our knowledge. Consequently, either various anti-apoptotic Bcl-2 members have overlapping roles in governing postnatal oocyte survival and maintenance of the adult ovarian reserve in mice, or the anti-apoptotic Bcl-2 member that regulates this decision has yet to be identified.     

Study of FMR1 gene association with ovarian dysfunction in a sample from the Basque Country

Premature ovarian failure (POF) is defined as cessation of menses before the age of 40. The most significant single gene associated with POF is the Fragile X Mental Retardation 1 gene (FMR1). In the present work we screened women with fertility problems from the Basque Country in order to determine, whether in these women, FMR1 CGG repeat size in the intermediate and premutation range was associated with their pathology, and whether intermediate and premutation carriers had endocrine signs of diminished ovarian function, using the most established measure of ovarian reserve, the gonadotropin FSH. A patient sample of 41 women with ovarian insufficiency and a control sample of 32 women with no fertility problems from the Basque Country were examined. The patient sample was classified into three categories according to the results of the retrospective assessment of their ovarian function. In group 2 of patients, women with irregular cycles, reduced fecundity and FSH levels ≥ 10 IU/l, there is a significant increase in the number of intermediate and premutation FMR1 alleles (35–54 CGG repeats). In group 3 of patients, women with amenorrhea for at least four consecutive months and FSH levels ≥ 10 IU/l, a significant increase in the number of intermediate FMR1 alleles (35–54 CGG repeats) was found in patients compared with controls. In this group all the patients had a serum concentration > 40 IU/l. The results suggest that in the analysed Basque sample the FMR1 gene has a role in the aetiology of POF. However, elevated FSH levels are more related to the menstrual cycle pattern than to the CGG repeat size.     

The impact investigation and adaptation strategy analysis of climate change on nature reserve in China

Nature reserve has been served as the important pathway for biodiversity conservation and carbon storage. Global climate change is an indisputable fact and impacted the biodiversity and nature reserve. How nature reserves adapt to climate change has drawn more and more concerns. This research conducted questionnaires of 68 national nature reserves from 24 provincial regions, and the questionnaires showed that all surveyed nature reserves experienced climate change, and 68.57%, 61.43% and 68.57% of nature reserves, respectively, considered warming temperature, precipitation change, and occurrence of extreme climate events as new threats to them. These new factors directly threat the distribution range and survival of endangered species, change of ecosystem function, enhance of pest and disease damages, and directed damage the infrastructures. However, most of the surveyed nature reserves did not consider the systematic monitoring the facts of climate change, and lack actions and strategies of initiative adaptation to climate change. At last, we proposed the strategies for nature reserves to adapt to climate change, including enhancing the monitoring on the impact of climate change, making scientific planning and designing for development of nature reserves, decreasing the pressure through sustainable development, and enhancing the scientific research and the investment to improve the ability of nature reserves to adapt to climate change.     

The effects of eccentric exercise on motor performance in young and older women

The purpose of the present study was to determine if old individuals show a greater exercise-induced decrement in motor performance and slower recovery compared to young individuals. Ten college-age women (23.6 years) and ten older women (67.4 years) performed an exercise consisting of 24 eccentric actions of the forearm flexors. In young subjects, eccentric exercise is known to produce repairable muscle damage. Before the exercise and for 5 days after, isometric strength, soreness, reaction time, and movement time were measured. For both groups, strength was reduced and soreness developed in the days following the exercise, generally indicating that muscle damage had occurred. The older subjects showed a slower strength recovery such that by 5 days after exercise they had not returned to their initial level of strength. There was no significant difference in soreness development between groups. Reaction time and movement time were not adversely affected by the exercise. Thus, the older subjects demonstrated a slower strength recovery after damage-inducing exercise, and, with regard to response speed, the older subjects could compensate for the impaired muscle function as well as the younger subjects.     

FMR1 repeat sizes in the gray zone and high end of the normal range are associated with premature ovarian failure

Premature ovarian failure (POF) is the occurrence of menopause before the age of 40 and affects 1% of the female population. Whereas the etiology of POF is largely unexplained, FMR1 premutation carriers are known to be at increased risk of POF compared with the general population. The FMR1 premutation alleles have 55–200 copies of a CGG repeat in the 5 untranslated region of the FMR1 gene. However, functional effects on gene expression may occur even for repeat sizes in what has been considered the normal range. To evaluate the role of the FMR1 repeat in POF, repeat sizes were examined in 53 women with idiopathic POF, 161 control women from the general population, and 21 women with proven fertility at an advanced maternal age. A significant increase in the number of FMR1 alleles between and including 35 and 54 CGG repeats was found in the POF patient population; 15 of 106 (14.2%) POF alleles were between and including 35 and 54 repeats, whereas only 21 of 322 (6.5%) alleles in the general population (P=0.02) and 2 of 42 (4.8%) alleles from women with proven late fertility (P=0.09) were of this size (P=0.01 versus combined controls). The effect was also significant for comparisons of genotype repeat size (repeat size weighted by the relative activity of the two FMR1 alleles) and biallelic mean (average size of the two alleles). These results are clinically relevant and suggest that the FMR1 gene plays a more significant role in the incidence of POF than has previously been thought.     

Association of PvuII polymorphism in ESR1 gene with impaired ovarian reserve in patients from Ukraine

The association of ESR1 PvuII polymorphism (rs2334693) with impaired ovarian reserve was studied by genotyping this polymorphism using PCR-RFLP in patients and two control groups from Ukraine. Statistically significant differences in the prevalence of p-allele frequency (?397T) was seen in the group of patients with impaired ovarian reserve (0.597) compared to control groups I under 35 years (0.480) and II over 35 years (0.453), both p < 0.05. The data suggest that PvuII polymorphism of ESR1 is associated with diminished ovarian reserve.     

The changes of DNA double-strand breaks and DNA repair during ovarian reserve formation in mice

DNA double-strand break (DSB) repair is crucial to maintain genomic stability for sufficient ovarian reserve. It remains unknown the changes of DSBs formation and DNA repair in germ cells during ovarian reserve formation in FVB/N mice. We demonstrated germ cell numbers increased significantly (all P < 0.05) from E11.5 to E13.5 and decreased significantly (all P> 0.05) until P2. OCT4 and SOX2 analyses indicated pluripotency peaks at E13.5 then decreases significantly (all P 0.05) until P2. γH2AX analyses revealed DSB formation significantly (P < 0.05) increased from E13.5 until P2. RAD51 and DMC1 data revealed homologous recombination (HR) pathway repair of DSBs is persistent active during meiosis (E13.5- P2) (all P> 0.05). 53BP1 and KU70 data indicate the non-homologous end-joining pathway (NHEJ) remains active during meiosis. 53BP1 expression was highest at E13.5 (P < 0.05). KU70 expression was higher in germ cells from E15.5 to P2 (all < P 0.05). PH3 and KI67 analyses revealed germ cell proliferation was not significantly different (all P> 0.05) from E13.5 to P2. Caspase-3 and TUNEL analyses showed germ cells apoptosis was not significantly different (all P > 0.05) from E13.5 to P2. In conclusion, we found both germ cell number and pluripotency peak at E13.5 and decline during meiosis. We demonstrated HR and NHEJ continually repair DSBs during meiosis. RAD51 and DMC1 are continuously expressed during meiosis. 53BP1 is mainly expressed at E13.5. KU70 continually functions from E15.5 to P2. Proliferating and apoptotic cells were rarely detected during meiosis. Results provide a basis for further study of how DSBs and DNA repair affect germ cell development.     

The influence of HER2 genotypes as molecular markers in ovarian cancer outcome

A relevant clinical problem in the treatment of ovarian cancer (OC) is the development of resistance to chemotherapy, frequently due to genetic variations in enzymes and receptors. Changes in the HER2 receptor have been associated with breast and ovarian cancers. The role of a polymorphism in the HER2 gene in the clinical outcome of OC patients was investigated in this study. We characterized DNA samples from 111 patients with OC treated with cisplatin and paclitaxel, using PCR-RFLP. Our results indicate that patients carrying the valine homozygotic genotype present a lower overall survival mean, suggesting a role for this polymorphism in the outcome of ovarian cancer patients. The G allele has been implicated in the formation of active HER2 receptors, with a more aggressive phenotype. We hypothesize that HER2 genotypes can be predictive biomarkers in ovarian cancer, contributing to a genetic individual profile of great interest in clinical oncology.     

The impact of baseline diameter on flow-mediated dilation differs in young and older humans

Flow-mediated dilation (FMD) has become a commonly applied approach for the assessment of vascular function and health, but methods used to calculate FMD differ between studies. For example, the baseline diameter used as a benchmark is sometimes assessed before cuff inflation, whereas others use the diameter during cuff inflation. Therefore, we compared the brachial artery diameter before and during cuff inflation and calculated the resulting FMD in healthy children (n=45; 10+/-1 yr), adults (n=31; 28+/-6 yr), and older subjects (n=22; 58+/-5 yr). Brachial artery FMD was examined after 5 min of distal ischemia. Diameter was determined from either 30 s before cuff inflation or from the last 30 s during cuff inflation. Edge detection and wall tracking of high resolution B-mode arterial ultrasound images was used to calculate conduit artery diameter. Brachial artery diameter during cuff inflation was significantly larger than before inflation in children (P=0.02) and adults (P<0.001) but not in older subjects (P=0.59). Accordingly, FMD values significantly differed in children (11.2+/-5.1% vs. 9.4+/-5.2%; P=0.02) and adults (7.3+/-3.2% vs. 4.6+/-3.3%; P<0.001) but not in older subjects (6.3+/-3.4% vs. 6.0+/-4.2%; P=0.77). When the diameter before cuff inflation was used, an age-dependent decline was evident in FMD, whereas FMD calculated using the diameter during inflation was associated with higher FMD values in older than younger adults. In summary, the inflation of the cuff significantly increases brachial artery diameter, which results in a lower FMD response. This effect was found to be age dependent, which emphasizes the importance of using appropriate methodology to calculate the FMD.     

Miscarriage rates after dehydroepiandrosterone (DHEA) supplementation in women with diminished ovarian reserve: a case control study

Background  

Dehydroepinadrosterone (DHEA) supplementation improves pregnancy chances in women with diminished ovarian reserve (DOR), by possibly reducing aneuploidy. Since a large majority of spontaneous miscarriages are associated with aneuploidy, one can speculate that DHEA supplementation may also reduce miscarriage rates.     

The Parkes lecture: controlled ovarian stimulation in women

Recent advances in knowledge of the endocrine and paracrine mechanisms that regulate human ovarian folliculogenesis have been parallelled by the introduction into clinical practice of new drugs that can be used safely and effectively to stimulate ovarian function in infertile women. Most notably, recombinant DNA technology has been applied to the production of molecularly pure forms of the gonadotrophins, FSH and LH, opening the way to the development of improved strategies for manipulating the ovarian paracrine system. The clinical objectives of controlled ovarian stimulation fall into two categories, depending on patient needs: (1) induction of multiple follicles from which mature oocytes can be harvested for use in assisted reproduction protocols such as in vitro fertilization and embryo transfer; or (2) induction of spontaneous ovulation of a single mature follicle so that conception might occur in vivo. This review summarizes the physiological principles upon which the use of gonadotrophins for clinical purposes is based, highlighting new opportunities for improved treatment as a result of the availability of recombinant FSH and LH.     

Effects of physical training on proprioception in older women

Older adulthood is accompanied by declines in muscular strength, coordination, function, and increased risk of falling. Resistance training increases muscular strength in this population but its effect on proprioception is unknown. To evaluate the effect of resistance training on proprioception, community dwelling older women completed a three-month exercise study. A resistance training (RT) group (N=19) underwent supervised weight training three times per week while a non-strength trained control (NSTC) group (N=19) performed range-of-motion activities that mimicked the movements of the RT group without the benefit of muscle loading. Subjects were evaluated at baseline, 6, and 12 weeks for strength and proprioception. Muscular strength was assessed by measuring the subject's one repetition maximum performance on four different exercises. Static proprioception was measured by the subject's ability to reproduce a target knee joint angle while dynamic proprioception was measured by the subject's ability to detect passive knee motion. The RT group made significant strength improvements compared to the NSTC group. Proprioception significantly improved in both groups by 6 weeks. Our findings suggest that improvements in proprioception can be obtained via regular activity that is independent of heavy muscle loading.     

The initial effects of low-volume strength training on balance in untrained older men and women

Evidence indicates that leg weakness in older adults is associated with decreased control of balance. The gender-specific implications of strength training on control of balance in older men and women remains unknown. This study examined the initial adaptations to 12 weeks of low-volume, single-set-to-failure strength training and its effect on quadriceps strength and control of multidirectional balance in previously untrained older men (n = 11) and women (n = 11) 59-83 years of age. Leg strength increased 23-30% (p < 0.001) across genders; however, the effect on balance varied between genders. No significant changes were noted in the women, whereas 37% (p < 0.014) more sway in the medial-lateral direction was noted in the men, with no change in the anterior-posterior direction. These results demonstrate that this training protocol may not be effective for improving balance and may lead to worsening of balance in older men.     

Aerobic exercise training reduces plasma endothelin-1 concentration in older women.

Endothelial function deteriorates with aging. On the other hand, exercise training improves the function of vascular endothelial cells. Endothelin-1 (ET-1), which is produced by vascular endothelial cells, has potent constrictor and proliferative activity in vascular smooth muscle cells and, therefore, has been implicated in regulation of vascular tonus and progression of atherosclerosis. We previously reported significantly higher plasma ET-1 concentration in middle-aged than in young humans, and recently we showed that plasma ET-1 concentration was significantly decreased by aerobic exercise training in healthy young humans. We hypothesized that plasma ET-1 concentration increases with age, even in healthy adults, and that lifestyle modification (i.e., exercise) can reduce plasma ET-1 concentration in previously sedentary older adults. We measured plasma ET-1 concentration in healthy young women (21-28 yr old), healthy middle-aged women (31-47 yr old), and healthy older women (61-69 yr old). The plasma level of ET-1 significantly increased with aging (1.02 +/- 0.08, 1.33 +/- 0.11, and 2.90 +/- 0.20 pg/ml in young, middle-aged, and older women, respectively). Thus plasma ET-1 concentration was markedly higher in healthy older women than in healthy young or middle-aged women (by approximately 3- and 2-fold, respectively). In healthy older women, we also measured plasma ET-1 concentration after 3 mo of aerobic exercise (cycling on a leg ergometer at 80% of ventilatory threshold for 30 min, 5 days/wk). Regular exercise significantly decreased plasma ET-1 concentration in the healthy older women (2.22 +/- 0.16 pg/ml, P < 0.01) and also significantly reduced their blood pressure. The present study suggests that regular aerobic-endurance exercise reduces plasma ET-1 concentration in older humans, and this reduction in plasma ET-1 concentration may have beneficial effects on the cardiovascular system (i.e., prevention of progression of hypertension and/or atherosclerosis by endogenous ET-1).     

The impact of missing and erroneous genotypes on tagging SNP selection and power of subsequent association tests

OBJECTIVE: Single nucleotide polymorphisms (SNPs) serve as effective markers for localizing disease susceptibility genes, but current genotyping technologies are inadequate for genotyping all available SNP markers in a typical linkage/association study. Much attention has recently been paid to methods for selecting the minimal informative subset of SNPs in identifying haplotypes, but there has been little investigation of the effect of missing or erroneous genotypes on the performance of these SNP selection algorithms and subsequent association tests using the selected tagging SNPs. The purpose of this study is to explore the effect of missing genotype or genotyping error on tagging SNP selection and subsequent single marker and haplotype association tests using the selected tagging SNPs. METHODS: Through two sets of simulations, we evaluated the performance of three tagging SNP selection programs in the presence of missing or erroneous genotypes: Clayton's diversity based program htstep, Carlson's linkage disequilibrium (LD) based program ldSelect, and Stram's coefficient of determination based program tagsnp.exe. RESULTS: When randomly selected known loci were relabeled as 'missing', we found that the average number of tagging SNPs selected by all three algorithms changed very little and the power of subsequent single marker and haplotype association tests using the selected tagging SNPs remained close to the power of these tests in the absence of missing genotype. When random genotyping errors were introduced, we found that the average number of tagging SNPs selected by all three algorithms increased. In data sets simulated according to the haplotype frequecies in the CYP19 region, Stram's program had larger increase than Carlson's and Clayton's programs. In data sets simulated under the coalescent model, Carlson's program had the largest increase and Clayton's program had the smallest increase. In both sets of simulations, with the presence of genotyping errors, the power of the haplotype tests from all three programs decreased quickly, but there was not much reduction in power of the single marker tests. CONCLUSIONS: Missing genotypes do not seem to have much impact on tagging SNP selection and subsequent single marker and haplotype association tests. In contrast, genotyping errors could have severe impact on tagging SNP selection and haplotype tests, but not on single marker tests.     

脆性X智力低下基因:分子遗传学和生物化学研究

脆性Ｘ综合征是最常见的遗传性智力低下疾病。该病是由于脆性Ｘ智力低下基因（ＦＭＲ１）功能丧失所致。ＦＭＲ１基因位于Ｘ染色体长臂末端,由１７个外显子组成,覆盖约３８ｋｂ,转录方向从着丝粒到端粒（ＧｅｎＢａｎｋＬ２９０７４）。分子遗传学研究和突变分析显示,...     

Genetic testing for women previously diagnosed with breast/ovarian cancer: examining the impact of BRCA1 and BRCA2 mutation searching

This study sought to investigate the impact of BRCA1 and BRCA2 mutation searching on women previously diagnosed with breast or ovarian cancer. In-depth interviews were undertaken with 30 women who had undergone a BRCA1 and BRCA2 mutation search within the clinical setting. The main reasons reported for undergoing mutation searching were: to provide genetic information for other family members, general altruism, curiosity about the aetiology of cancer, and to provide information to facilitate risk management decisions. In the main, the process of undergoing genetic testing was not experienced as anxiety provoking. The benefit of receiving a result confirming the presence of a genetic mutation was seen as an end to uncertainty, whereas the costs included difficulties in disclosing information to kin and potentially increased anxiety about one's own or others' cancer risks. Women receiving an inconclusive test result reported a range of emotional reactions. There was evidence that some women misunderstood the meaning of this result, interpreting it as definitive confirmation that a cancer-predisposing mutation was not present within the family. It is concluded that women with cancer who participate in BRCA1 and BRCA2 testing need to receive clear information about the meaning and implications of the different types of test results. Some recommendations for clinical practice are discussed.