• Journal of Aquaculture
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• v.19 no.2
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• pp.99-108
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• 2006

Sex of the Nile tilapia Oreochromis niloticus is mainly determined by an XX/XY system. However, accumulating evidences suggest the existence of additional sex modifying factors including environmental, autosomal and parental influences. In order to investigate the possibility of parental effects on sex ratios of tilapia progenies, in this study, a series of crosses was carried out using gynogenetic clonal fish, neomales, normal males and females, and YY fish. Crosses between clonal XX male and clonal female have yielded only female progenies and no parental influences were observed. However, in the crosses between clonal males and normal females, female parents were significantly associated with the progeny sex ratios ($X^2$=20.046, 7 d.f., p<0.01). Progeny sex ratios from the crosses between neomales and normal females ($X^2$=60.491, 5 d.f and $X^2$=28.072, 2 d.f.) also showed significant association with female parents (P<0.001). The stability of progeny sex ratios from repeated spawns were confirmed by using 6 different parental pairs. In 16 crosses between normal males and normal females, sex ratios of progenies showed clear maternal influences, and further analysis of the results revealed a negative correlation ($r^2$=0.7718, p<0.05) between the sex ratios of progenies from two different males, indicating a strong paternal influence. No statistically significant relationship between survival rates and sex ratios of progenies was observed in any genotypic groups. Taken together, the influence of parental pairs on progeny sex ratios in this species is evident although the cause of this influence is not clear.

• The Korean Journal of Zoology
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• v.13 no.1
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• pp.15-20
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• 1970

The present study was undertaken in an attempt to see if the segregation frequency of a third chromosome was changed by changing the sex chromosome which were free of SD in the second chromosome. The eight genotype males having different sex chromosome constitution each were constructed by appropriate matings and the two standard laboratory stocks of Drosophila melanogaster, e and se were used as the third chromosome recessive markers for the present experiment. The results of the present investigation are given below: 1. The k values which are the proportion of the se third chromosomes recovered among progeny flies from the mating of se/e males to e females were highly signiicantly different among the four genotypes and between the two sexes,and the interaction of genotype and sex was significantly different. Thus the setregation frequency of the se third chromosome in the male, when made heterozygous with the e third chromosome, was dependent upon the sex chromosome constitution. 2. Both of the k(Woman) and the k(man) remains roughly constant among genotypes. 3. The sex ratio o the se progeny class was highly significantly heterogeneous among the four genotypes but it was homogeneous for the e progeny class. 4. The values of the k(man) and the sex ratio of the se progeny class, on the average, were higher than that of the k(Woman) and of the e progeny class, respectively. 5. Those phenomena suggest that some sort of prezygotic selection could be operating such that the combination of the e third chromosome and the Y chromosome tends to be eliminated before fertilization. This tendency argues for a re-examination of the viability estimations of Drosophila melanogaster.

• Journal of Aquaculture
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• v.20 no.3
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• pp.190-193
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• 2007

Viability, early growth and sex ratio of induced gynogenetic diploid bagrid catfish (Leiocassis ussuriensis, Siluriformes) were examined. Survival rates of gynogenetic diploids and normal bi-parental diploids up to 180 days post hatching were not significantly different (P>0.05), and consequently resulted the mean percent survivals of 76% (gynogens) and 78% (bi-parental progeny) at the end of growth trial. Growth in both body weight and total length of gynogenetic diploids was also similar to those of normal diploid controls (P>0.05). Gynogenetic bagrid catfish displayed a similar level of ovarian development when compared to bi-parental diploid females, as judged at 10 weeks post hatching. Sex ratio of bi-parental progeny was normal 1:1 whereas all-femaleness was observed in gynogenetic progeny (P<0.05), suggesting that the genetic sex determination mechanism of this species should be XX-XY based female homogamety.

• Journal of Aquaculture
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• v.9 no.2
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• pp.125-132
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• 1996

A study was carried out to test sex ratio of the progeny that were induced by the artificial fertilization between normal female and gynogenetic diploid eggs and sex-reversed gynogenetic diploid male sperm. Sex reversed gynogenetic diploid males were produced successfully in gynogenetic diploid female by immersion treatment with $17{\alpha}$-methyltestosterone at the concentration of 10 pub from $13.5{\pm}0.22$ mm to $57.6{\pm}5.1$ mm in total length. In $F_1$ progeny test, matings between normal females and sex-reversed gynogenetic males were not produced all female, but matings between gynogenetic diploid females and sex-reversed gynogenetic males were produced all female populations in six out of eight groups and two lots produced $96.9\%$ and $95\%$ female. These data showed that all-female populations were produced by crossing between gynogenetic diploid female and sex reversed gynogenetic diploid male.

• Proceedings of the Korean Society of Applied Entomolohy Conference
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• 2000.05a
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• pp.128-128
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• 2000

• International Journal of Industrial Entomology and Biomaterials
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• v.29 no.1
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• pp.128-134
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• 2014

Nesolynx thymus Girault (Hymenoptera: Eulophidae) is one among 20 hymenopteran parasitoids reported to attack the uzi fly, Exorista bombycis, which in turn infests the silkworm, Bombyx mori accounting a cocoon yield loss of 10-20%. A host of factors viz., age and size of host, age and size of parasitoid, availability of host, temperature and quality of host are reported to influence the reproductive efficiency of the parasitoids. In the present study an attempt was made to record the influence of foraging parasitoid density on their reproductive performance. Three day-old uzi pupae were offered to varying numbers (1 - 10) of 2 day old Nesolynx thymus adults for parasitization. The progeny production per pupa (84.44 - 132.77) increased significantly with increase in the number of foraging parasitoid adults (1 - 10) however, progeny production per female decreased. The sex ratio (M : F) (1:25.49 - 1:1.53) decreased significantly with increase in foraging parasitoid adults. The morphometric parameters except female abdomen width of first generation parasitoid showed significant negative correlation with number of foraging adults. However, correlation between the parasitoid size in first generation and their reproductive performance was nonsignificant.

• Journal of Embryo Transfer
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• v.31 no.1
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• pp.65-72
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• 2016

This study was conducted to examine effects of mating type on the growth traits in an $F_2$ population produced by reciprocal intercrosses between Landrace and the Jeju Native Black pig (JBP). The $F_2$ progeny were produced by two different mating types based on the grand dams of founder breeds JBP (Cross_1) and Landrace (Cross_2). The body weights at 21 days after birth (BW21D) was significantly different between Cross_1 and Cross_2 (P<0.05), showing that the BW21D of Cross_1 has about 0.25 kg heavier than Cross_2. The significant differences were found between males and females for the growth traits including the body weights (BWB, BW21D, BW70D and BW140D) and average daily gains (ADG, eADG and lADG) (P<0.05). Males were heavier BWB, BW21D and BW140D levels, and higher ADG and lADG levels than females. On the other hand, females had heavier BW70D and higher eADG levels than those of males. When considering the mating types and sex simultaneously the Cross_2 males had the heaviest BW140D among the combinations of cross and sex. In conclusion, it is desirable to choose Landrace as grand dams in the reciprocal intercrosses between Landrace and JBP for producing their progeny construction and to plan the production of $F_2$ males for industrial purposes. These results suggested that it may be one of useful strategies to improve the productivity through out selection of the mating type of founder breeds and the progeny sex, especially in Landrace, JBP and their related populations.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.10
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• pp.1379-1387
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• 2013

In a majority of mammals, male infants have heavier body mass and grow faster than female infants. Accordingly, male offspring nursing requires a much greater maternal energy contribution to lactation. It is possible that the maternal-fetal immunoendocrine dialog plays an important role in female preparation for lactation during pregnancy. Immune system genes are an integral part of gene regulatory networks in lactation and tumor necrosis factor alpha ($TNF{\alpha}$) is a proinflammatory cytokine that also plays an important role in normal mammary gland development. The aim of this study was to evaluate the influence of the sex of calf and/or the -824A/G polymorphism in the promoter region of $TNF{\alpha}$ gene on milk performance traits in Black Pied cattle over the course of lactation. We also studied the allele frequency differences of -824A/G variants across several cattle breeds, which were bred in different climatic conditions. The G allele frequency decreased gradually over the course of lactation events in the Black Pied dairy cattle because of a higher culling rate of cows with the G/G genotype (p<0.001). In contrast to the genotypes A/A and A/G, cows with G/G genotype showed significant variability of milk and milk fat yield subject to sex of delivered calf. Milk yield and milk fat yield were significantly higher in the case of birth of a bull calf than with a heifer calf (p<0.03). The G allele frequency varies from 48% to 58% in Grey Ukrainian and Black Pied cattle to 77% in aboriginal Yakut cattle. Our results suggest that the $TNF{\alpha}$-824A/G gene polymorphism may have an influence on the reproductive efforts of cows over the course of lactation events depending on the sex of progeny. Allocation of resources according to sex of the calf allows optimizing the energy cost of lactation. This may be a probable reason for high G allele frequency in Yakut cattle breeding in extreme environmental conditions. Similarly, the dramatic fall in milk production after birth of a heifer calf increases the probability of culling for the cows with the G/G genotype in animal husbandry.

• Korean Journal of Animal Reproduction
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• v.13 no.1
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• pp.40-48
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• 1989

Guppy fry were treated for the first 40 days of life with 0, 20, 40, 60 & 100$\mu\textrm{g}$ of estradiol per gram of food in order to change the sex of normal males to functional females(genetic male). The present investigation deals with the effects of steroid hormones, such as $\beta$-estradiol and testosterone, on the sex differentiation in guppy and tilapia. The results obtained were summarized as follows. 1. In B (20$\mu\textrm{g}$/g diet) group 17$\beta$-estradiol-treated, 67.8% of male offsprings were produced. 2. In D (60$\mu\textrm{g}$/g diet) group 17$\beta$-treated, 67% of female offsprings were produced. 3. B, D groups of genetic male brooders had significantly different effects (P<0.01) upon sex ratios of their progeny. 4. This strongly indicates that sex direction has been achieved and that the male is the heterogametic sex. 5. The group that produced the highest percentage of male offspring(male percentage of observed number to expected number was 91%) contained only full-sibling male brooders to the sex-reversed female brooders. 6. After 7 months following treatment, the sex-reversed males had ovarian portion in the anterior region and a testicular portion in the posterior region of the same intersexual gonad, respectively. 7. At 7 months after treatment, the ovareis revealed a complete arrest of the ovarian formation, and appearances of spermatogenetic cell cysts among surviving auxocytes. 8. In most of sex-reversed fish, anterior portion of test is was devoid of sperm ducts including the seminal vesicle and vas deferens. 9. The male transferrin showed two strong bands, while the female transferrin showed a single weak band. 10. One of the two bands of male transferrin showed the same mobility with band of female transferrin.

• International Journal of Industrial Entomology and Biomaterials
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• v.4 no.2
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• pp.117-120
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• 2002

Scelionid eggParasitoids Play an important role in biological control of some economically important pentatomids. Stink bug (Canthecona furcellatta Wolff,) is an important predator of Tasar silkworm larvae (Antheraea mylitta D.) and causes 30-40 percent loss in tasar silk industry. Psix striaticeps (Scelionid: Hymenoptera) has been found to be an important egg parasitoid. The parasitization potential of f striaticeps is mere than 60 percent and the sex ratio is female oriented. Studies indicate that the maintenance of existing scelionid population by avoiding harmful practices and the augmentation of scelionids either directly releasing them in the field or by indirectly making the field environment more favorable for them is an important aspect to control the pentatomid population in sericulture. Female bias sex ratio is advantageous to increase the parasitoid population in the field. 24-hour-old egg of stink bug and one-day old parasitoid is suitable for producing maximum progeny. 1 : 30 of parasitoid: host ratio is needed to regulate the estimated population in silkworm rearing field.