• Journal of Ecology and Environment
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• v.30 no.3
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• pp.277-280
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• 2007

Social spiders consistently show highly female-biased sex ratios. However, the sex ratio of subsocial spiders, which have been suggested as an intermediate stage of the evolutionary pathway towards permanent sociality, is generally unknown. We investigated the sex ratio and approximate date of fertilization of the subsocial spider, Amaurobius ferox Walckenaer (Araneae: Amaurobiidae). Investigation over 2 years revealed that sex ratio of A. ferox was consistent across years and averaged 0.49. By early May $(1^{st}{\sim}10^{th})$, 66.6% of female A. ferox observed in the field had already been inseminated, and by late May $(21^{st}{\sim}31^{th})$, 95.4% of females had been inseminated. This result suggests that A. ferox need a long time or cold temperatures to prepare them for reproduction after the developmental attainment of the adult stage.

• Journal of dental hygiene science
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• v.6 no.2
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• pp.65-77
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• 2006

In this study, we surveyed the increasing rate of the licensed medical technicians from the year of 1970 to 2003 in Korea along with the investigation of the growth ratio by sex and fields among the licensed medical technicians. On the basis of this survey, this study aims to provide a milestone for the further studies to resolve the problems arising from asymmetry of sex ratio in some specific fields of medical technicians and oversupply of the in-service technicians. The results show that in contrast to the year 1970, the whole growth rate was 59.46%, males 28.98%, females 285.21%. In the case of sex ratio, in 1970 the figure of males to females was 6.63 to 1 but the figure of 2003 was 0.67 to 1, which indicates the number of female technicians are badly increasing. Until 2003, the ratio of female technicians was higher than the male technicians in the fields of medical technologists, physical therapists, dental hygienists, occupational therapists, medical record technicians but in radiologist technological, dental technicians and opticians the ratio was reversed.

• Korean Journal of Animal Reproduction
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• v.12 no.1
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• pp.37-41
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• 1988

These studies were carried out to examine the sex of preimplantation mouse embryo. For the investigation of sex-ration of mouse embryos, morula and blastocysts stage embryos treated with H-Y antiserum (10%, v/v) and FITC anti-mouse-IgG were divided into the positive and negative embryos. Positive and negative identified embryos were observed the viability according to the in vitro cultured and the sex ratio was also investigated by chromosomal analysis. The results obtained in these studies were summarized as follows: 1. Two hundred sixty-seven recovered embryos of morula or blastocyst stage were incubated in medium containing H-Y antiserum and FITC anti-mouse-IgG. Positively or negatively identified embryos were 139 and 128. This trend indicated the approximal sex ratio was 1:1. 2. Sex ratio was measured using the embryos treated with indirect immunofluorescence assay to examine the relationship between embryo developmental stage and sex ratio. Sex ratio of morula stage embryos was 45.2% positive and 54.8% negative, on the other hand, the ratio switched to 56.4% positive and 43.6% negative embryo in blastocyst stage. 3. Fourty-seven positive and 57 negative embryos were obtained out of 104 morula stage embryos treated with indirect immunofluorescence assay. Survived positive or negative embryos during in vitro culture were 42 and 49, respectively out of 47 and 57 embryos. 4. The numbers of negative and positive embryos were 171 and 92 out of 163 blastocyst embryos which were incubated in the medium containing H-Y antiserum and FITC anti-mouse-IgG. The result of karyotype test showed the successful rate of sexing embryo is positive and negative embryos was63.0% (58/92) and 62.0% (44/71). The final female to male ratio within 58 positive embryos was 22.7:77.6, and the ratio of the 44 negative embryos was 77.3:22.7.

• Development and Reproduction
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• v.25 no.1
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• pp.55-57
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• 2021

Samples were collected from the subtidal region of Jumunjin on the eastern coast of Korea in July 2020. A total of 338 mussels of shell height (SH) 20.8-149.8 mm were used for sex ratio analysis. The sex ratio (F:M) in the same population of mussel Mytilus coruscus was approximately 1:0.7. The sex ratio according to the class of SH was different. The sex reversal pattern of M. coruscus appears to go from male → female → male → female, and as such is determined to be sequential hermaphrodites.

• Journal of Ecology and Environment
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• v.43 no.3
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• pp.320-331
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• 2019

Background: Dioecious plant species having both male and female plants have been investigated regarding sex-related characteristics such as sex ratio, sex-differential resource requirements, and spatial segregation of the sexes. Habitat loss and fragmentation are major threats to the survival of plant populations, but dioecious species are particularly more prone to such habitat degradation than non-dioecious species because of their dimorphic sexual system. We examined the sex-related demographics of two Ilex cornuta populations being different regarding land use history. Methods: During 2016-2017, we examined I. cornuta trees with a basal diameter ${\geq}1.5cm$ in the Yongsu-ri population (YS population) and the Gotjawal Provincial Park population (GP population). Plant sex (male, female, or unsexed) was identified. The tree size (basal diameter and height of the main stem), clonal production (the ramet numbers per genet), and vitality for each clone were measured. The associations between population, sex, tree size, clonal production, and vitality were examined using ANOVAs and contingency table analyses. Finally, point pattern analyses using O-ring statistics were conducted to assess spatial patterns. Results: Upon excluding unsexed trees, the YS population with 74 trees was significantly male-biased (0.66), while the GP population with only 26 trees had a 1:1 sex ratio. In both populations, males and females did not differ in tree size. Although the mean number of ramets differed significantly between populations, females tended to produce more ramets than males. The proportion of weak trees was significantly higher in the YS than in the GP population. Neither population showed evidence of spatial segregation of the sexes. Conclusions: The two populations of dioecious I. cornuta are characterized by the small number of trees and relatively high frequencies of non-reproductive trees. Both indicate that these populations are quite susceptible to environmental and genetic stochasticity. On the other hand, the differences between populations in sex ratio, clonal production, and vitality suggest that conservation efforts for I. cornuta need to be population-specific. In order to help recover and enable this vulnerable species to persist, it is necessary to find ways to enhance their sexual reproduction and simultaneously reduce habitat disturbances due to anthropogenic activities.

• Korean Journal of Animal Reproduction
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• v.20 no.4
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• pp.443-451
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• 1997

These studies were conducted to determine the sex of preimplantation Hanwoo embryos produced in vitro using polymerase chain reaction(PCR). Y chromosome specific and bovine speicific DNA primers were synthesized and tested for embryo sexing. Bovine IVF embryos were produced in TCM 199 and CR1aa medium, and classified by developmental stages on Day 7 to 9. The effects of developmental rates to bovine IVF blastocysts on sex ratio were also investigated using PCR methods. The results obtained in this study were as follows; 1. Developmental rates to blastocyst from IVM/IVF embryos in TCM 199 and CR1aa medium for 9 days were 23.5 and 30.2%, respectively, and there was significant difference between the media(P<0.05). 2. Male to female ratio of early, mid, expanded and hatching balstocyst produced on Day 7 were 0.7:1, 1.4:1, 2.2:1, and 2.5:1, respectively, and male embryos was significantly higher proportion in expanding and hatching blastocysts(P<0.01). 3. On Day 8, male to female ratio of early, mid, expanded and hatching blastocysts were 0.6:1, 1:1, 2.5:1, and 2.7:1, respectively. Both expanded and hatching blastocysts obtained a significantly higher proportion of males(P<0.01). 4. The male : female ratio of early, mid, expanded and hatching blastocyst produced on Day 9 was 0.6:1, 0.8:1, 1:1, and 2.2:1, respectively. Hatching blastocysts had a significantly higher ratio of males(P<0.01). The developmental rate of IVM/IVF embryos to blastocyst for 9 day culture was higher in CR1aa than that in TCM 199 medium. For the sex ratio by developmental stages of IVF embryos, male ratio was higher in expanded blastocyst but female in early blastocysts.

• Korea journal of population studies
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• v.20 no.1
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• pp.65-96
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• 1997

The main purpose of this study is to explore the determinants of sex ratio imbalance at birth in Taegu which has experienced the extremely imbalanced sex ratio at birth since mid-1980s. This paper attempts to compare the determinants of sex ratio imbalance at birth, such as sex discrimination against women, son preference, prenatal sex identification followes by sex-selective induced abortions, among married women aged 25 to 44 in Taegu with those in Bay area, California in USA. The research is based on the survey data which were conducted in Taegu, Repulic of Korea and Bay area, California in USA. The findings of this analysis suggest that married women in Taegu are more likely to feel sex discrimination against women than married women in Bay area. Furthermore, the percentage of married women's effort for son bearing before pregnancy is much higher than that of married women in Bay area. We also have found that the percentage of sex-selective induced abortion in Taegu is six times higher than that of married women in Bay area. According to the logistic regression analysis, the determinants of sex-selective induced abortion among married women in Taegu are discrimination against women, son preference, prenatal sex identification. On the other hand, age is the only variable which has an important impact on sex-selective induced abortion among married women in Bay area. From the findings of this study, we can conclude that son preference based on Cofucianism is the most important impact on sex ratio imbalance at birth in Taegu where son preference is much stronger than other regions in Korea. The phenomenon of extremely imbalanced sex ratio at birth in Taegu is the result of combination of these factors, such as strong son preference, seeking to have at least one son within small family size, and prenatal sex identification followed by sex-selective induced abortion.

• Korea journal of population studies
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• v.17 no.2
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• pp.116-135
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• 1994

China's population and family planning program has heen successful. Women's fertility as measured by total fertility rate (TFR) has declined from 5.8 in 1970 to 2.3 in 1990, accordingly the annual crude birth rate(CBR) has declined from 34 per thousand in 1970 to 21 per thousand in 1989, and the annual natural growth rate from 2.6 percent in 1970 to 1.4 percent in 1989 (Coale and Chen, 1987; SSB, 1991; Gu, 1994). While this is indeed an astonishing achievement for a developing country to have its fertility down to replacement within a short period, some new issues emerging along with the rapid fertility decline require careful considerations. One of them is the uprising of the sex ratio at birth in China. The 1990 population census reported the sex ratio at birth in China of 113.8 in 1989, which is ohviously much higher than the acceptable level of normal ratio around 106. It has received since then a lot of tention in China and abroad, among demographic professionals and governmental agencies alike (Hull, 1990; Johansson and Nygren, 1991; Xuand Guo, 1991; Tu, 1993; Gu and Xu, 1994; among others). Based on the available demographic data and research results this paper will first have a review of the patterns and trends of sex ratio at birth in China, then turn to the immediate causes of abnormal sex ratio at birth and the determinants of the son preference, followed with a conceptual framework for understanding of the phenomenon, and finally the policy implications and recommendations will be discussed.

• Korean Journal of Animal Reproduction
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• v.10 no.2
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• pp.182-187
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• 1986

As a fundamental study to increase the fertility and to modify the sex ratio in cattle, highly motile sperm were separated by bovine serum albumin gradients. The pregnancy rates of Korean native cow and Holstein cow, and the sex ratio between AI and natural mating were also investigated. The results obtained were as follows. 1. First service pregnancy rate of Korean native cow in artificial insemination was higher than that of Holstein. 2. At secondary sex ratio in artificial insemination and natural mating, male ratio in artifical insemination was slightly higher than that in natural mating. 3. The sperm separated from marketed frozen semen using 6%, 10% and 20% bovine serum albumin showed significantly high value in motility, percent of normal sperm and progressive motility as compared with control sperm.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.10
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• pp.1411-1416
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• 2014

Gender selection is important in livestock industries; for example, female calves are required in the dairy industry. Sex-sorted semen is commonly used for the production of calves of the desired gender. However, assessment of the sex ratio of the sorted semen is tedious and expensive. In this study, a rapid, cost effective and reliable method for determining the sex ratio was developed using a multiplex real-time polymerase chain reaction (PCR) assay. In this assay, the X and Y chromosome-specific markers, i.e., bovine proteolipid protein (PLP) gene and sex-determining region Y (SRY) were simultaneously quantified in a single tube. The multiplex real-time PCR assay was shown to have high amplification efficiencies (97% to 99%) comparable to the separated-tube simplex real-time PCR assay. The results obtained from both assays were not significantly different (p>0.05). The multiplex assay was validated using reference DNA of known X ratio (10%, 50%, and 90%) as templates. The measured %X in semen samples were the same within 95% confidence intervals as the expected values, i.e., >90% in X-sorted semen, <10% in Y-sorted semen and close to 50% in the unsorted semen. The multiplex real-time PCR assay as shown in this study can thus be used to assess purity of sex-sorted semen.