Evidence for two unlinked sex reversal loci in the Nile Tilapia, Preochromis niloticus, and linkage of one of these to the autosomal red body colour gene

Ismihan Karayucel, Tariq Ezaz, Sedat Karayucel, Brendan McAndrew, David Penman

Research output: Contribution to journalArticle

Abstract

Gynogenetic offspring from heterozygous red (Rr) Oreochromis niloticus females were produced by UV irradiation of sperm and suppression of the second meiotic division. The distance between the red gene and the centromere was estimated to be 4.8 cM. Of 547 gynogenetic offspring that survived to be sexed, 54 (9.9%) were males. There was a significant association between colour and sex -- 53 of the male fish were red and only one was wild type. These data provide evidence for genetic linkage between the red gene and a gene that can cause female-to-male sex reversal. Of several fully inbred XX clonal lines of O. niloticus previously developed in our laboratory, only one contained males. To test if this is caused by the same gene as the red-linked autosomal sex reversal gene, a series of test crosses was carried out. Males from this line were crossed to homozygous red females, then some of the offspring, which were all females, were backcrossed to the parental males. If the same gene was causing the presence of males in the gynogenetic offspring and in the clonal line, we would expect that in the backcrosses there would be more males in the wild type than in the red fish. However, the frequency of males was not significantly different between the red and wild-type fish (18/162=11.1% and 18/173=10.4% males, respectively), which leads to the conclusion that different unlinked loci are responsible for the presence of males in the clonal line and in the gynogenetics from the heterozygous red females
Original languageEnglish
Pages (from-to)51-63
Number of pages13
JournalAquaculture
Volume234
Issue number1-4
Publication statusPublished - 2004
Externally publishedYes

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sex reversal
Oreochromis niloticus
linkage (genetics)
loci
color
gene
genes
fish
testcrosses
centromeres
sperm
irradiation

Cite this

Karayucel, Ismihan ; Ezaz, Tariq ; Karayucel, Sedat ; McAndrew, Brendan ; Penman, David. / Evidence for two unlinked sex reversal loci in the Nile Tilapia, Preochromis niloticus, and linkage of one of these to the autosomal red body colour gene. In: Aquaculture. 2004 ; Vol. 234, No. 1-4. pp. 51-63.
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abstract = "Gynogenetic offspring from heterozygous red (Rr) Oreochromis niloticus females were produced by UV irradiation of sperm and suppression of the second meiotic division. The distance between the red gene and the centromere was estimated to be 4.8 cM. Of 547 gynogenetic offspring that survived to be sexed, 54 (9.9{\%}) were males. There was a significant association between colour and sex -- 53 of the male fish were red and only one was wild type. These data provide evidence for genetic linkage between the red gene and a gene that can cause female-to-male sex reversal. Of several fully inbred XX clonal lines of O. niloticus previously developed in our laboratory, only one contained males. To test if this is caused by the same gene as the red-linked autosomal sex reversal gene, a series of test crosses was carried out. Males from this line were crossed to homozygous red females, then some of the offspring, which were all females, were backcrossed to the parental males. If the same gene was causing the presence of males in the gynogenetic offspring and in the clonal line, we would expect that in the backcrosses there would be more males in the wild type than in the red fish. However, the frequency of males was not significantly different between the red and wild-type fish (18/162=11.1{\%} and 18/173=10.4{\%} males, respectively), which leads to the conclusion that different unlinked loci are responsible for the presence of males in the clonal line and in the gynogenetics from the heterozygous red females",
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Evidence for two unlinked sex reversal loci in the Nile Tilapia, Preochromis niloticus, and linkage of one of these to the autosomal red body colour gene. / Karayucel, Ismihan; Ezaz, Tariq; Karayucel, Sedat; McAndrew, Brendan; Penman, David.

In: Aquaculture, Vol. 234, No. 1-4, 2004, p. 51-63.

Research output: Contribution to journalArticle

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T1 - Evidence for two unlinked sex reversal loci in the Nile Tilapia, Preochromis niloticus, and linkage of one of these to the autosomal red body colour gene

AU - Karayucel, Ismihan

AU - Ezaz, Tariq

AU - Karayucel, Sedat

AU - McAndrew, Brendan

AU - Penman, David

PY - 2004

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N2 - Gynogenetic offspring from heterozygous red (Rr) Oreochromis niloticus females were produced by UV irradiation of sperm and suppression of the second meiotic division. The distance between the red gene and the centromere was estimated to be 4.8 cM. Of 547 gynogenetic offspring that survived to be sexed, 54 (9.9%) were males. There was a significant association between colour and sex -- 53 of the male fish were red and only one was wild type. These data provide evidence for genetic linkage between the red gene and a gene that can cause female-to-male sex reversal. Of several fully inbred XX clonal lines of O. niloticus previously developed in our laboratory, only one contained males. To test if this is caused by the same gene as the red-linked autosomal sex reversal gene, a series of test crosses was carried out. Males from this line were crossed to homozygous red females, then some of the offspring, which were all females, were backcrossed to the parental males. If the same gene was causing the presence of males in the gynogenetic offspring and in the clonal line, we would expect that in the backcrosses there would be more males in the wild type than in the red fish. However, the frequency of males was not significantly different between the red and wild-type fish (18/162=11.1% and 18/173=10.4% males, respectively), which leads to the conclusion that different unlinked loci are responsible for the presence of males in the clonal line and in the gynogenetics from the heterozygous red females

AB - Gynogenetic offspring from heterozygous red (Rr) Oreochromis niloticus females were produced by UV irradiation of sperm and suppression of the second meiotic division. The distance between the red gene and the centromere was estimated to be 4.8 cM. Of 547 gynogenetic offspring that survived to be sexed, 54 (9.9%) were males. There was a significant association between colour and sex -- 53 of the male fish were red and only one was wild type. These data provide evidence for genetic linkage between the red gene and a gene that can cause female-to-male sex reversal. Of several fully inbred XX clonal lines of O. niloticus previously developed in our laboratory, only one contained males. To test if this is caused by the same gene as the red-linked autosomal sex reversal gene, a series of test crosses was carried out. Males from this line were crossed to homozygous red females, then some of the offspring, which were all females, were backcrossed to the parental males. If the same gene was causing the presence of males in the gynogenetic offspring and in the clonal line, we would expect that in the backcrosses there would be more males in the wild type than in the red fish. However, the frequency of males was not significantly different between the red and wild-type fish (18/162=11.1% and 18/173=10.4% males, respectively), which leads to the conclusion that different unlinked loci are responsible for the presence of males in the clonal line and in the gynogenetics from the heterozygous red females

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