Tetraploid Males Research Articles

Chromosome studies of progenies of tetraploid female rainbow trout

Nine induced tetraploid females were artificially inseminated by UV-irradiated sperm collected from diploid males, in order to induce the gynogenetic development of their ova. Most of the resulting embryos were diploid (or minor aneuploids). Several gynogenetic tetraploids, likely to issue from unreduced ova, were also detected in these progenies. The same females fertilized by normal sperm of diploid males gave a majority of triploids and several pentaploids, while the fertilization by normal sperm of tetraploid males gave rise to a majority of tetraploids and one hexaploid. The same crosses, after the eggs had been heat-shocked to double the maternal genetic contribution, yielded about three-quarters pentaploids and one quarter haploids (normal sperm of diploids), or three-quarters hexaploids and one quarter diploids (normal sperm of tetraploids). These haploids and diploids are likely to result from androgenesis.

Evaluation of juvenile rainbow trout survival and growth in half-sib families from diploid and tetraploid sires

Five diploid and eight first-generation tetraploid males were mated with a pool of diploid females, with and without retention of the second polar body by heat shock, and the progenies were studied up to the sixth month after hatching. Apart from the poor fertilizing capacity of the tetraploid sires inducing low hatching rates, further survival and growth of the second-generation triploids were similar to those of the triploids obtained from diploid sires and heat shock. Second-generation tetraploids obtained from tetraploid sires and heat shock were inferior to the other ploidy types in post-hatching survival and growth. These characters were affected by a large variation of paternal origin, suggesting that genetic improvement would be possible.

Metabolic utilization of diets by polyploid rainbow trout ( Salmo gairdneri)

1. 1. Nitrogen (NH 4) excretion and oxygen consumption were measured in four groups of juvenile rainbow trout (36–40 g): triploids obtained by a heat shock treatment (3n); triploids obtained by mating diploid females with tetraploid males (3n/4n); tetraploids (4n) and a diploid control (2n). 2. 2. No differences in daily N excretion patterns and in N excretion rate measured as a percentage of N intake were detected between groups. 3. 3. Oxygen consumption of the 2n group was significantly inferior to that of the 3n and 4n groups but not to the 3n/4n group. 4. 4. SDA, specific dynamic action (measured as a percentage of the energy intake), ranged from 5.6 to 8.6% and was not different between groups. 5. 5. Protein energy catabolism measured as per cent of total energy expenditure was significantly higher in the 2n group than in polyploid groups.

Production of second generation triploid and tetraploid rainbow trout by mating tetraploid males and diploid females ? Potential of tetraploid fish

First generation tetraploids were produced by hydrostatic pressure treatment before the first cleavage and raised until the adult stage. Their survival and growth were severely depressed when compared to the diploid control: after two years, no ovulated females were found although males produced sperm at 1 and 2 years of age and were mated individually with diploid females. The progenies were consistently normal with high survival rates. They were found to be almost all triploids by karyology, which failed to detect a significant rate of aneuploidies. However, the fertilizing ability of tetraploid males was always low (0 to 97% of the control; average 40%). Several arguments presented here support the hypothesis that diploid spermatozoas, which are wider than haploid ones, would be frequently blocked during their penetration through the micropyle canal. Second generation tetraploids were produced after such matings by heat shocks, causing the retention of the second polar body. Their survival and growth were much more satisfactory than in the first generation, although still lower than in diploid and triploid controls issuing from diploid parents. Performances of second generation triploids were comparable to those of diploids, and slightly better than those of conventional triploids issuing from diploid parents. 94.5% of the second generation tetraploids were male.

Tetraploid rainbow trout produced by cytochalasin B

At the Research Station for Salmonids, Sunndalsøra Unit, tetraploid rainbow trouts have been produced by keeping newly fertilized eggs for a short time in a solution containing cytochalasin B. The purpose of this work is to produce triploid sterile fish by fertilizing normal eggs with sperm from tetraploid males.

<i>Melandrium</i> ノ倍數體

1. A number of male and female tetraploids have been induced in Melandrium album by colchicine method.2. Conjugations of sex chromosomes at the meiotic divisions in the induced tetraploid males are illustrated in figs. 5 a-f and table 3.3. The induced tetraploids and normal diploids were intercrossed and a considerable number of seedlings were obtained (table 4). Some of them have been examined cytologically and determined to be triploid (figs. 8-9), tetraploid (fig. 10) or heteroploid (fig. 11).4. In comparing size relations between the X and the Y chromosomes in somatic cells, it was ascertained that the Y is the larger member of the sex chromosomes.