Sex-related Growth Differences Research Articles

Increased maternal serum hCG concentrations in the presence of a female fetus as early as 2 weeks after IVF-ET

BackgroundMaternal serum human chorionic gonadotropin (hCG) is produced in trophoblast cells during pregnancy. Whether there are sex-related growth differences of hCG concentrations in early pregnancy is still controversial. ObjectiveTo explore the association between hCG concentrations and fetal sex as early as 2 weeks after in vitro fertilization and embryo transfer (IVF-ET). MethodsThis study involved 6669 women ≤ 38 years of age. These 6669 patients all delivered singletons; 3531 had a male fetus and 3138 had a female fetus. The maternal serum hCG concentrations on Day 14 and Day 21 were determined using a Beckman DxI800 immunoassay system. ResultsAmong the 6669 patients who delivered singletons, 3531 had a male fetus and 3138 had a female fetus. The hCG concentrations on day 14 of gestation were 516.12 (342.12–757.34) IU/L in the group of male fetuses and 552.69 (359.35–772.83) IU/L in group of female fetuses. The hCG concentration on day 21 was 8839.60 (5975.00–12615.00) IU/L in male fetuses and 9289.10 (6162.00–13146.00) IU/L in female fetuses. Maternal serum hCG levels were significantly higher in those with female fetuses than those with male fetuses. After adjusting for confounding factors, the hCG levels were significantly associated with fetal sex. ConclusionsOur results showed pregnant women with female fetuses have significantly higher hCG levels than those bearing male fetuses.

Sex-Related Differences in Growth, Herbivory, and Defense of Two Salix Species

Sex-related differences in sex ratio, growth, and herbivory are widely documented in many dioecious plants. The common pattern is for males to grow faster than females and to be less well-defended against herbivores, but Salix is an exception. To study sex-related differences in the patterns of resource allocation for growth and defense in willows, we conducted a large-scale field experiment to investigate the flowering sex ratio, mortality, growth traits, insect herbivory and content of defensive substances in three Salix populations comprising two species. Results demonstrate that the two Salix suchowensis Cheng populations have a female bias in the sex ratio, whereas no bias is found in the S. triandra L. population. Male individuals in the S. suchowensis populations have significantly higher mortality rates than females. However, the mortality rate of S. triandra population has no gender difference. This finding may be one of the explanations for the difference in sex ratio between the two species. The females are larger in height, ground diameter, and biomass, and have a higher nutritional quality (N concentration) than males in both species. Nevertheless, slow-growing males have a higher concentration of the defense chemical (total phenol) and lower degrees of insect herbivory than females. Additionally, biomass is positively correlated with herbivory and negatively correlated with defense in the two willow species. It is concluded that the degrees of herbivory would have a great influence on resource allocation for growth and defense. Meanwhile, it also provides important implications for understanding the evolution of dioecy.

Difference in Developmental Kinetics of Y-Specific Monoclonal Antibody Sorted Male and Female In Vitro Produced Bovine Embryos.

Sex-related growth differences between male and female embryos remain an attractive subject for reproductive biologists. This study aimed to investigate the endogenous factors that play a crucial role in the pace of early development between male and female bovine embryos. Using sex pre-selected semen by Y-specific monoclonal antibodies for the production of bovine embryos, we characterized the critical endogenous factors that are responsible for creating the development differences, especially during the pre-implantation period between male and female embryos. Our results showed that at day seven, (57.8%) Y-sperm sorted in vitro cultured embryos reached the expanded blastocyst (BL) stage, whereas the X-sperm sorted group were only 25%. Y-BLs showed higher mRNA abundance of pluripotency and developmental competency regulators, such as Oct4 and IGF1-R. Interestingly, Y-sperm sorted BLs had a homogeneous mitochondrial distribution pattern, higher mitochondrial membrane potential (∆Ѱm), efficient OXPHOS (oxidative phosphorylation) system and well-encountered production of ROS (reactive oxygen species) level. Moreover, Y-blastocysts (BLs) showed less utilization of glucose metabolism relative to the X-BLs group. Importantly, both sexes showed differences in the timing of epigenetic events. All these factors directly or indirectly orchestrate the whole embryonic progression and may help in the faster and better quality yield of BL in the Y-sperm sorted group compared to the X counterpart group.

Secondary Growth and Carbohydrate Storage Patterns Differ between Sexes in Juniperus thurifera.

Differences in reproductive costs between male and female plants have been shown to foster sex-related variability in growth and C-storage patterns. The extent to which differential secondary growth in dioecious trees is associated with changes in stem carbohydrate storage patterns, however, has not been fully assessed. We explored the long-term radial growth and the seasonal variation of non-structural carbohydrate (NSC) content in sapwood of 40 males and 40 females Juniperus thurifera trees at two sites. NSC content was analyzed bimonthly for 1 year, and tree-ring width was measured for the 1931–2010 period. Sex-related differences in secondary growth and carbohydrate storage were site-dependent. Under less restrictive environmental conditions females grew more and stored more non-soluble sugars than males. Our results reinforce that sex-related differences in growth and resource storage may be a consequence of local adaptation to environmental conditions. Seasonal variation in soluble sugars concentration was opposite to cambial activity, with minima seen during periods of maximal secondary growth, and did not differ between the sexes or sites. Trees with higher stem NSC levels at critical periods showed higher radial growth, suggesting a common mechanism irrespective of site or sex. Sex-related patterns of secondary growth were linked to differences in non-soluble sugars content indicating sex-specific strategies of long-term performance.

Early maternal serum ß-human chorionic gonadotropin (ß-hCG) levels and sex-related growth difference of IVF embryos.

Maternal serum ß-human chorionic gonadotropin (ß-hCG) represents the trophoblastic cell mass and is an indirect measurement of embryo development at early implantation stage. Studies in animals and human embryos detected sex-related growth differences (SRGD) in favour of male embryos during the pre-implantation period. The purpose of our study was to correlate SRGD and maternal serum ß-hCG at 16 days after embryo transfer. We retrospectively analysed all (fresh and frozen) non-donor, single embryo transfers (SET), elective and not elective, that were performed between December 2008 and December 2013. We included ß-hCG values from day 16 after oocyte collection of pregnancies resulting in live birth. Neonatal gender was retrieved from patient files. Male and female embryos were further grouped to cleavage and blastocyst stage transfers. Regression analysis for confounding variables included maternal age, maternal body mass index (BMI), use of micromanipulation (ICSI), embryo quality (grade), assisted hatching, day of transfer and fresh or frozen embryo transfer. Seven hundred eighty-six non-donor SETs resulted in live birth. After including only day 16 serum ß-hCG results, 525 SETs were analysed. Neonatal gender was available for 522 cases. Mean maternal serum ß-hCG levels were similar, 347 ± 191 IU/L in the male newborn group and 371 ± 200 IU/L in the female group. The difference between ß-hCG levels remained insignificant after adjusting for confounding variables. Early maternal ß-hCG levels after embryo transfers did not represent SRGD in our study.

Sex-related differences in growth and carbon allocation to defence in Populus tremula as explained by current plant defence theories.

Plant defence theories have recently evolved in such a way that not only the quantity but also the quality of mineral nutrients is expected to influence plant constitutive defence. Recently, an extended prediction derived from the protein competition model (PCM) suggested that nitrogen (N) limitation is more important for the production of phenolic compounds than phosphorus (P). We aimed at studying sexual differences in the patterns of carbon allocation to growth and constitutive defence in relation to N and P availability in Populus tremula L. seedlings. We compared the gender responses in photosynthesis, growth and whole-plant allocation to phenolic compounds at different combination levels of N and P, and studied how they are explained by the main plant defence theories. We found no sexual differences in phenolic concentrations, but interestingly, slow-growing females had higher leaf N concentration than did males, and genders differed in their allocation priority. There was a trade-off between growth and the production of flavonoid-derived phenylpropanoids on one hand, and between the production of salicylates and flavonoid-derived phenylpropanoids on the other. Under limited nutrient conditions, females prioritized mineral nutrient acquisition, flavonoid and condensed tannin (CT) production, while males invested more in above-ground biomass. Salicylate accumulation followed the growth differentiation balance hypothesis as low N mainly decreased the production of leaf and stem salicylate content while the combination of both low N and low P increased the amount of flavonoids and CTs allocated to leaves and to a lesser extent stems, which agrees with the PCM. We suggest that such a discrepancy in the responses of salicylates and flavonoid-derived CTs is linked to their clearly distinct biosynthetic origins and/or their metabolic costs.

Sex-related growth differences are present but not enhanced in in vitro fertilization pregnancies

To determine whether IVF modifies the effect of fetal sex on growth. Retrospective cohort study. Tertiary care center and related facilities. Singleton live births without fetal/maternal comorbidities from fertile women who conceived without the use of assisted reproductive technologies and infertile women who conceived with IVF. None. The primary outcome was birth weight (BW). Secondary outcomes were fetal crown-rump length (CRL) in the first trimester, biparietal diameter (BPD), and estimated fetal weight (EFW) in the second trimester. There were no differences in baseline characteristics between women carrying male fetuses and those carrying female fetuses in either mode of conception. In unadjusted analyses, the male-female differentials in fetal BPD and BW were more pronounced in the IVF cohort than in the unassisted cohort. In multivariable regression analysis, male BPD exceeded female BPD by 0.12 cm, male EFW exceeded female EFW by 12 g, and male BW exceeded female BW by 172 g. IVF did not have a significant effect on BPD but was associated with a 52 g increase in EFW in the midgestation. IVF was associated with an 81-g reduction in BW. IVF did not modify the magnitude of size differences between the sexes in the midgestation or at birth. Comparable sex-dependent differential growth occurs in unassisted and IVF pregnancies.

The relationship between growth and sex differentiation in the European sea bass (Dicentrarchus labrax)

The phenotype results from the interaction between the genotype and the environment but how a given environment drives the expression of a particular sexual phenotype is poorly understood. The European sea bass has a polygenic sex determining mechanism influenced by temperature and, as in any poikilotherm, temperature also affects growth rates. However, the exact relationship between growth and sex differentiation remains elusive. To analyze this relationship, two experiments involving the manipulation of fish growth with or without a previous size-grading were carried out. In the first experiment, sex ratios of non-size-graded fish were unaltered after disturbing growth rates at three different times during the sex differentiation period corresponding to fish of 8–12cm standard length (SL). The groups with a reduction of their food intake (hence showing slow growth rates) exhibited catch-up growth after returning to normal feeding levels and also exhibited a degree of gonadal differentiation and maturation similar to that of the controls. In the second experiment, fish of ~4cm SL, i.e., before the appearance of the first known differences in aromatase expression (5–6cm SL), were size-graded and then subdivided into groups which were differentially fed to maximize differences in their resulting growth rates. Highly significant differences in sex ratios were found, with more females in the groups derived from the group with the largest fish at the time of grading irrespective of subsequent growth rates. Together, these results show that in the European sea bass sex-related differences in growth are established before the appearance of the currently known first molecular markers of sex and that growth rates during the sex differentiation period do not affect sex ratios. Based on these results, we propose the 3–4cm as the size range where possible earlier differences between sexes should be looked for at the molecular level in the European sea bass. Moreover, from an applied point of view, we suggest that improvement of aquaculture protocols for this species might be achieved by combining size-grading to discard slow growing fish, and hence males, together with the control of the catch-up growth response in an attempt to reduce the amount of required food.

Sex-related growth differences are enhanced in IVF pregnancies

Previous studies in spontaneously conceived pregnancies show that male neonates are larger than female neonates. Recent data suggests these growth differences are present even in the embryo. We sought to determine if the effect of fetal sex on growth differs in pregnancies achieved by in vitro fertilization.

Growth rate of human preimplantation embryos is sex dependent after ICSI but not after IVF

There is concern that IVF and/or ICSI might have an adverse effect on embryonic development via epigenetic alterations. Such alterations might also be involved in the sex-related growth differences in preimplantation embryos found in some animal species. In the present study we analysed cell numbers of human male and female surplus embryos that developed to the blastocyst stage after either IVF or ICSI in order to investigate possible sex-dependent differential growth rates. Blastocysts resulting from surplus embryos obtained after either IVF or ICSI during a 5 year study period were analysed using fluorescence in situ hybridization (FISH). The number of cells and sex could be determined in 330 blastocysts collected from 92 IVF cycles and in 322 blastocysts collected from 121 ICSI cycles. Whereas female and male embryos originating from IVF showed comparable mean log cell numbers per embryo +/- SEM (3.76+/-0.05 in 147 female and 3.72+/-0.04 in 183 male embryos), significant differences were observed in embryos originating from ICSI (3.57+/-0.05 in 162 female and 3.90+/-0.03 in 160 male embryos). The sex-related growth difference was significantly greater in ICSI than in IVF embryos. In a subset of 84 embryos, inner cell mass (ICM) and trophectoderm (TE) were analysed separately. A significantly higher mean log cell number of TE cells in ICSI male embryos was found as compared to their female counterparts (3.44+/-0.12 in 16 female and 3.90+/-0.11 in 29 male embryos), whereas this difference was not found in IVF embryos. A clear sex-related growth difference was found in human blastocysts originating from ICSI, but not in blastocysts originating from IVF. It is as yet unknown which mechanism is responsible for our findings. We hypothesize that the ICSI procedure might interfere with the process of imprinted X-inactivation.

Are sex steroids involved in the sexual growth dimorphism in Eurasian perch juveniles?

Individual growth and food intake were monitored in Eurasian perch ( Perca fluviatilis L.) juveniles (13.5±3.4 g initial body weight) to determine whether androgens and estrogens may mediate sex-related growth differences. Fish were individually tagged with chips and implanted with cocoa butter containing 20 μg of either 17α-methyltestosterone (MT) or 17β-estradiol (E 2) per gram of fish body; controls were implanted with cocoa butter without hormones. All fish were bled at the end of the experiment for measurement of E 2 in females and testosterone (T) in males (MT was not measured) and triiodothyronine (T3) in both genders. Survival, gonadosomatic index and hepatosomatic index were not affected by steroid treatments. Relative food intake (RFI), feed efficiency (FE) and specific growth rate (SGR) were higher in females than in males in all treatments. MT treatment significantly lowered RIF, FE and SGR in both sexes, while E 2 treatment showed no significant effect on growth and feeding parameters. In contrast to E 2 and T concentrations, T3 levels were significantly and positively correlated with SGR and RFI. The results provide evidence that MT may affect sexually related growth dimorphism by decreasing food intake and FE in Eurasian perch.

Sex-related differences in growth and morphology of blue mussels

The morphology and growth pattern of male and female blue mussels (Mytilus edulis) from the north Norfolk coast, UK, were studied. In allometric terms, the external shell parameters of females grew faster relative to shell length than those of males. In absolute terms, females also grew more quickly than males for all external shell parameters and for most internal body parts. At a given age, females are therefore larger than males. Females had a higher shell to tissue weight ratio and a relatively heavier foot than males. A discriminant function incorporating age, weight and shell length, width, and height correctly sexed 81% of individuals in the sample from which it was derived. Both natural and sexual selection may be involved in the evolution of sexual dimorphism in blue mussels.

Longitudinal relationship among growth, nutritional status, and pulmonary function in children with cystic fibrosis: Analysis of the Cystic Fibrosis Foundation National CF Patient Registry

Objective: To determine prospectively the relationship among growth, nutritional status, and pulmonary function over a 4-year period in a large cohort of children with cystic fibrosis (CF). Study design: CF Foundation National CF Patient Registry data collected from 1991 to 1995 for 968 children (507 male) aged 5 to 8 years with pancreatic insufficiency and forced expiratory volume in 1 second within 60% to 140% of predicted values (FEV1%) were analyzed longitudinally. Variables hypothesized to affect FEV1% included age, sex, z scores for height, weight, percent of height-appropriate body weight, and annual number of days hospitalized. Results: The significant decline in FEV1% was curvilinear and dependent on baseline FEV1%; children with initial FEV1% ≥90 declined 2.6 U/y more than those with initial FEV1% <90. Boys gained but girls declined in z scores for height. Girls decreased in z scores for weight at a greater rate than boys. The z scores for weight and percent of height-appropriate body weight were significantly associated with longitudinal changes in FEV1%, after adjustment was done for hospitalizations. Conclusions: Growth, nutritional status, and pulmonary function are not stable in prepubertal children with CF and pancreatic insufficiency. Important sex-related differences in growth occur before puberty. Growth and nutritional status are associated with changes in FEV1%, suggesting that nutritional intervention may slow the decline in pulmonary function in children with CF. (J Pediatr 2000;137:374-80)

Skewed embryonic sex ratios in a viviparous fish: a result of endocrine disruption?

Sex ratios in catches of wild adult fish are often affected by sex related differences in growth, behaviour and survival. Therefore, such sex ratios may not reflect the relative number of males and females that are recruited to the population. However, this can be circumvented by studying unborn fish embryos. We have found skewed sex ratios among embryos from the viviparous eelpout ( Zoarces viviparus) which could indicate exposure to endocrine disrupting chemicals. The sex ratio was close to 50/50 at two presumably clean sites from Kattegat/Skagerrak and two from the Baltic Sea. On the Swedish Baltic coast near a large pulp mill the relative number of female embryos was significantly lower (42%; P=0.006) but approached 50% further south in the discharge gradient. Treatment of females during early pregnancy with methyltestosterone inhibited oocyte development in all embryos, and instead testis-like tissue was formed. Thus, masculinization found in the field could be caused by exposure to androgen mimics or substances interfering with steroid-synthesis, activity or excretion. This may arise from exposure to the pulp mill effluents, since endocrine disruption in fish has been reported earlier near North American mills. Irrespectively of the cause, reduced numbers of female offspring may have negative impacts on the recruitment capacity of a population.

Protein Kinase C Isozyme Pattern in Liver Hyperplasia

Lead nitrate, a potent activator of protein kinase C, is able to induce reversible rat liver hyperplasia. This phenomenon shows sex-related growth differences: liver hyperplasia as well as its regression by apoptosis occurred earlier and was more pronounced in male than in female rats. Dietary choline administration to females causes a shift of growth pattern towards the male values. Analysis of protein kinase C isoenzymes with hydroxylapatite column chromatography at time points crucial for lead-induced liver proliferation in male, female and choline-treated female rats showed a significant down-regulation of β and α PKC activities and a marked activation of epsilon PKC. The fluctuation of these activities could be related to the rates of DNA synthesis. These data suggest that the observed PKC isoenzymes could be involved in the signal transduction pathway leading to lead-induced liver proliferation.

Size Grading May Alter Sex Ratios of Fingerling Channel Catfish

The influence of size grading on sex ratios and growth was evaluated for small (0.2- 4.0 g) channel catfish (Ictalurus punctatus). Channel catfish from 15 families were ungraded or were graded into two or three size-groups by mean of bar graders with 0.40-0.99-cm slot widths. The 57 groups obtained were reared separately for 3-4 months in 150-L fiberglass tanks. Weight, length, and sex were then determined on up to 100 fish per group. The frequency of males from all families was 51.5%: although progeny from individual families varied from 45.1 to 56.0% males, the frequencies were not different from the expected 1:1 male: female ratio. Males usually were preferentially selected (mean ± SD, 65.1 ± 3.5%) by a grader with a slot width of 0.91 cm, which retained the largest fish in a population; graders with smaller slot widths did not consistently affect the sex distribution. Harvest size of finger lings was variable and was influenced by initial weights and densities; family-by-grader interactions were significant (P s 0.05). Sexually dimorphic growth was observed in 19 of 57 tanks, and in those instances males were always larger than females. Variances for weight and length between sexes were different in less than 10% of the tanks, and the magnitude of the variance differences was significantly influenced by families. These results suggest that grading fingerlings as small as 3 g can affect sex ratios and that channel catfish families may be selected to enhance or decrease sex-related growth differences.