Sex ratio of offspring of patients with prostatic cancer

We have examined the fertility of 354 patients with prostatic cancer and 597 controls who had married at least once and formed part of a population-based case-control study in Alberta. Considering offspring of both sexes, the mean fertility of the patients was 3.17, not significantly different from the mean of 3.11 for the controls. However, the sex ratios were significantly different, 56.5% of the patients'' offspring being sons, compared with 50.1% of the controls'' offspring. The difference in sex ratio persisted after adjustment for ethnic group, level of education and age at first marriage, which were found to be risk factors for prostatic cancer.     

Mitochondrial DNA variations associated with recurrent pregnancy loss among Indian women

Several genetic factors have been found to be associated with recurrent pregnancy loss (RPL). However, not many attempts have been made to associate the mitochondrial DNA (mtDNA) variations with RPL. Therefore, we have analyzed the complete mtDNA of 100 women with RPL and 12 aborted fetal tissues. Our analysis revealed a total of 681 variations, most of which were in NADH Dehydrogenase (ND) genes that encode mitochondrial enzyme Complex I. Presence of T4216C variation (ND1 gene) in 9% of the RPL women and several pathogenic, and novel mutations suggest the role of mtDNA variations in RPL.     

Sex ratio in the offspring of parents with chronic radiation exposure from nuclear testing in Kazakhstan

The former Soviet Union conducted a nuclear test program in the Semipalatinsk region of northeastern Kazakhstan in 1949-1989. The population in the vicinity of the test site was chronically exposed to radiation fallout, especially from above-ground tests during 1949-1956. Male:female sex ratio has been proposed as a measure of reproductive health, with some reports suggesting an alteration in the sex ratio of offspring of parents exposed to radiation. We investigated the impact of radiation exposure and other factors on the sex ratio in the population inhabiting the exposed region. A total of 11,464 singleton births of 3,992 mothers exposed to radiation during 1949-1956 were analyzed. The overall sex ratio was 1.07, similar to the current sex ratio in Kazakhstan (1.06). The sex ratio increased from 1.04 where mothers received <20.0 cSv to 1.12 where mothers received > or =60.0 cSv. However, the linear trend across exposures was not significant (P = 0.42). No consistent association was found between the sex ratio and the time since parental radiation exposure, parental age at exposure, or year of birth. Sex ratio was significantly associated with maternal age, birth order and possibly ethnicity but not with paternal age, parental educational level or season. In conclusion, no significant association was found between radiation exposure level and sex ratio, but some previously suggested demographic factors were positively associated with sex ratio.     

Variation in offspring sex ratio in women of differing social status

Since Trivers and Willard first postulated 15 years ago that offspring sex ratio might be adaptively manipulated by parents of mammalian species as well as hymenoptera, evidence has been accumulating in support of this hypothesis. Research suggests that female mammals are able to manipulate the secondary (birth) sex ratio of their offspring based upon their own social status and/or access to resources. This ability is thought to procure a reproductive advantage by maximizing number of grandchildren. This article reports, in further confirmation of the Trivers and Willard hypothesis, the apparent sex ratio manipulation of offspring by human females of differing social status, in a polygynous, naturally fertile population, the nineteenth-century Mormons.     

Sex preferences for offspring among men in the western area of Sierra Leone

This study reveals evidence of a significant sex preference among men. Programmes aimed at changing men's views on the importance of the sex of a child must be implemented in order to reduce the desired family size and eventual fertility.     

Abnormal relaxin secretion during pregnancy in women with type 1 diabetes

To test the hypothesis that relaxin may play a role in the fetal abnormalities associated with pregnancy in type 1 diabetic women, we previously compared gestational relaxin concentrations in diabetic and clinically normal women using a porcine relaxin radioimmunoassay (RIA): Serum immunoactive relaxin was significantly (P < 0.001) elevated in the diabetic women. To confirm and extend this work in a larger group of subjects, we have now used an enzyme-linked immunosorbent assay (ELISA) specific for human H2 relaxin (the normal human gene product) to determine immunoactive serum relaxin concentrations in serial samples from 61 Type 1 diabetic and 21 normal pregnant women. Samples from 22 of the diabetic and nine of the normal women were also directly compared in the porcine relaxin RIA. ELISA-determined serum relaxin was higher (P < 0.001) at 24 and 36 weeks of pregnancy in type 1 diabetic women than in controls, confirming previous findings. However, the geometric mean increase in immunoactive relaxin concentration in identical samples from pregnant diabetic women over that of controls was significantly greater with the RIA than with the ELISA (271% vs 44%; P < 0.001). To investigate this discrepancy, the specificity and epitope selectivity of the RIA and the ELISA were compared using several synthetic polypeptides, including human relaxins H1 and H2, and relaxin and insulin derivatives. Both assays showed great specificity, but the porcine RIA selectively identified the epitopes of the receptor-binding domain of the relaxin B chain and cross-reacted strongly with H1 and H2 relaxins. In contrast, only the H2 peptide was detected by the ELISA antiserum. Therefore, the marked discrepancy between the RIA and the ELISA could be due to the presence in the diabetic samples of another relaxin-like molecule in addition to the normal H2 relaxin. The biological consequences of elevated serum relaxin in diabetic pregnancy remain to be elucidated.     

Sex ratio at birth and family composition in sub-saharan Africa: inter-couple variations

In this study, sex ratios at birth (male/female births) were found to vary according to family composition. Using Demographic and Health Survey (DHS) maternity histories from sub-Saharan Africa, the study shows that the sex ratio at birth increases with the number of previous male births and decreases with the number of previous female births. For families with only males, the sex ratio increases from 1.046 for the first birth to 1.083 for the 8th birth. For families with only females, the sex ratio decreases from 1.046 for the first birth to 0.942 for the 8th birth. The differences were highly significant when tested with a linear logistic model (p=0.018 for males; p=1.85 x 10(-11) for females). The effect was not symmetrical, and was found to be significantly stronger for females. These effects could be reproduced assuming a strong heterogeneity between couples. The distribution of sex ratios was fitted with an asymmetrical log-gamma function, which revealed a wide range of variation in the sex ratio between 0.50 and 1.30, and a peak around 1.14. The results and their implications are discussed in the light of former findings in France and in the United States of America.     

Sex ratio among human embryos and newborns in a Russian population

Summary A comparative study was performed on the sex ratio among embryos and newborns in a Russian population (Moscow).The secondary sex ratio was studied in 81 914 babies born in different regions of Moscow during the period 1962–1971. It was 105.8 boys to 100 girls. Neither maternal age nor month of birth was observed to have any effect on the secondary sex ratio.The sex chromatin was studied in 3000 embryos obtained from induced abortions. The ratio of male to female embryos was 103.4:100. It dose not differ from either Mendelian segregation (1:1) or the secondary sex ratio in a population studied. It was calculated that more precise determination of the sex ratio in the embryonal period would require the study of not less than 17 500 embryos.The confidence limits are presented for the significance of possible differences in the sex ratio in samples ranging from 100 to 500000 in size.

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Zusammenfassung In einer russischen Bevölkerung (Moskau) wurde das Geschlechts-verhältnis unter Embryonen und Neugeborenen verglichen.Das sekundäre Geschlechtsverhältnis (bei Neugeborenen) wurde bei 81 914 in Moskau geborenen Babys für den Zeitraum 1962–1971 untersucht. Ergebnis: 105,8 : 100. Weder das Alter der Mutter noch die Jahreszeit beeinflußte diesen Wert.Bei 3000 Embryonen aus induzierten Aborten wurde das Sex-Chromatin bestimmt. Es ergab sich ein Verhältnis 103,4 : 100 . Es besteht weder ein Unterschied zu dem erwarteten 1:1-Verhältnis noch zu dem sekundären Geschlechtsverhältnis. Für eine genauere Bestimmung wäre eine Stichprobe an mindestens 17 500 Embryonen erforderlich.Es werden die Vertrauensgrenzen für eine mögliche Änderung des Geschlechtsverhältnisses bei Stichprobengrößen von 100 bis 500000 Beobachtungen angegeben.

     

Sex ratio variation among broods of great reed warblers Acrocephalus arundinaceus

The sex of 746 great reed warbler fledglings (from 175 broods) was determined by the use of single primer polymerase chain reaction. The reliability of the technique was confirmed as 104 of the fledglings were subsequently recorded as adults of known sex. The overall sex ratio did not differ from unity. Variation in sex ratios between broods was larger than expected from a binomial distribution. Female identity explained some of the variation of brood sex ratio indicating that certain females consistently produced sex ratios that departed from the average value in the population. The theory of sex allocation predicts that parents should adjust the sex ratio of their brood to the relative value of sons and daughters and this may vary in relation to the quality of the parents or to the time of breeding. In the great reed warbler, the proportion of sons was not related to time of breeding, or to any of five female variables. Of five male variables, males with early arrival date tended to produce more daughters. The sex ratio of fledglings that were a result of extra-pair fertilizations did not differ from that of legitimate fledglings. Hence, there is currently no evidence of that female great reed warblers invest in a higher proportion of sons when mated with attractive males.