Boris Gomelsky

Ionic composition and osmolality of paddlefish (Polyodon spathula, Acipenseriformes) seminal fluid

Changes in ionic composition as Na+,K+, Ca2+ and Mg2+, osmolality inseminal fluid, percentage of motile spermatozoaand velocity were investigated in response toCPP and different dosage of LHRHa. The lowestvelocity of sperm was observed after use CPPtreatment. The velocity of spermatozoa,significant main effect of the treatment(P < 0.0001) and the time of sperm collection(P < 0.0104) were evaluated. The osmolality ofseminal fluid was different betweenexperimental groups of LHRHa (48.0–62.7mOsmol.kg−1) and CPP (33.0–46.3mOsmol.kg−1) treatments. The osmolalitywas significantly higher on the first day andone-half, then declined on day three, rangingfrom 33.0 to 62.7 mOsmol.kg−1. Analysisof variance showed significant main effects ofthe treatment (P < 0.0001) and the time ofsperm collection (P < 0.0002) on the osmolalityof seminal fluid. The level of Na+ andK+ ion was different between experimentalgroups of LHRHa and CPP treatment. The highestconcentration of 11.11 mmol.l−1 wasobserved at Na+ ion. Then theconcentrations declined on the level 1.56, 0.52and 0.36 mmol.l−1 for K+, Ca2+and Mg2+ ions, respectively. There werehighly positive correlations between osmolalityof seminal fluid and dosage of LHRHa treatment(r = 0.84), velocity of spermatozoa andosmolality of seminal fluid (r = 0.57) andosmolality of seminal fluid and Na+concentration at seminal fluid (r = 0.70).Injection with LHRHa increased quality of spermas velocity of sperm, level of Na+,K+ and osmolality at seminal fluidcompared to CPP treatments.

Induced gynogenesis in black crappie.

Abstract This study reports the results of initial experiments on induced diploid gynogenesis in black crappie Pomoxis nigromaculatus. White bass Morone chrysops were an effective sperm donor for gynogenetic experiments with black crappies. White bass spermatozoa fertilized black crappie eggs, but hybrid larvae were not viable and died after hatching. In a series of experiments, we determined the ultraviolet (UV) light dose required to inactivate the sperm genome and the heat shock parameters needed to restore diploidy. Black crappie eggs were inseminated with white bass sperm irradiated with UV dosages ranging from 25 to 2,500 J/m2. A typical “Hertwig effect” in the yield of hatched larvae was observed with dosages greater than 100 J/m2. The genetic inactivation of paternal chromosomes was confirmed by flow cytometry measurement of DNA content in larval cells. Larvae resulting from sperm irradiated at a dose of 1,000 J/m2 were haploid. Time durations of mitotic interval (τ0) at different temperatures for...

Hormonal Sex Reversal and Evidence of Female Homogamety in Black Crappie

Abstract This study reports the results on hormone-induced sex reversal in black crappie Pomoxis nigromaculatus and the sex ratios of progenies obtained from test crosses of androgen-treated males with normal females. The androgen 17α-methyltestosterone (MT) was orally administered to fish with an artificial diet (30 mg/kg) for 30 d beginning 37 d after hatching; mean fish lengths were 35 and 55 mm at the beginning and conclusion of the treatment, respectively. The MT-treated group consisted of 95% males and 5% intersex fish, while the sex ratio in the control group was not significantly different from 1:1. Four males from the androgen-treated group were individually test-crossed with normal females to identify sex-reversed males according to the sex ratios in progenies and to reveal the chromosomal mechanism of sex determination in black crappie. Two out of three analyzed progenies consisted of females only, while one progeny had a sex ratio not significantly different from 1:1. The appearance of all-fem...

Progress in Studies on Hormonal Sex Reversal and Genetic Sex Control in Black Crappie

Sex control can solve the problem of stunted black crappie populations in small impoundments. The main objectives of the present study were (1) to identify sex-reversed males of black crappie from a previously obtained androgen-treated group using test crosses, and (2) to develop broodstock of sex-reversed males by masculinization of fish from those crosses. An additional objective of the study was to try to identify sex-specific RAPD markers, which might be used for identification of sex-reversed males. The progenies resulting from test crosses were divided into two groups: Group I (control) fish were raised without hormonal treatment, while Group II fish were subjected to androgen (MT) treatment. Seven progenies were obtained from the cross of preliminary androgen-treated males with normal females. Six of seven progenies had sex ratio in Groups I close to 1:1, and one progeny consisted of females only. This shows that only one male, which generated this progeny, was a sex-reversed homogametic fish (XX) while the other males were heterogametic normal (XY) fish. In Group II the androgen 17α-methyltestosterone (MT) was orally administered to crappie with an artificial diet (30 mg/kg) for 40 days beginning 35 days post hatching; androgen-treated groups consisted of 95–100% males. Sex-specific random-amplified polymorphic DNA markers were not identified in black crappie.

Effectiveness of the Minimally Invasive Surgical Technique (MIST) for Removal of Ovulated Eggs from First-Time and Second-Time MIST-Spawned Paddlefish

Abstract A minimally invasive surgical technique (MIST) for the removal of ovulated eggs from paddlefish Polyodon spathula was tested on broodstock that had been previously spawned using MIST to determine whether repeat spawning affected fecundity or hatching rate compared with broodstock than had not previously been induced to spawn. There were no significant differences in the number of eggs removed or in the hatching rate between first- and second-time MIST spawners. The oviducts from second-time MIST spawners appeared normal and had no scarring or blockage. The MIST approach is efficient, practical, and less stressful to broodstock during artificial propagation than other reported egg collection procedures.

Inheritance of Sparkling Scales (Ginrin) Trait in Ornamental Koi Carp

AbstractThe purpose of this study was to investigate mechanisms of inheritance of the sparkling scales (ginrin) trait in ornamental koi, a variant of Common Carp Cyprinus carpio. The fish segregations of ginrin : nonginrin were recorded in three F1 progenies obtained by crosses of ginrin × nonginrin and 16 F2 progenies obtained by crosses of ginrin × ginrin and nonginrin × nonginrin. The segregations of ginrin : nonginrin in most F1 progenies did not differ significantly from the 1:1 Mendelian ratio, while crossing nonginrin fish from F1 progenies resulted in the appearance of only nonginrin fish in F2. Based on these data, it was suggested that the ginrin trait in koi is controlled by a dominant mutation of one gene (Gr/gr): fish with genotypes GrGr and Grgr have ginrin phenotype, while fish with genotype grgr do not possess this trait. In most analyzed F2 progenies obtained by crosses of ginrin × ginrin, the ginrin : nonginrin segregations were statistically different from the 3:1 and 2:1 theoretical ra...

Koi ×Goldfish Hybrid Females Produce Triploid Progeny when Backcrossed to Koi Males

Abstract Hybrids of koi (an ornamental variant of the common carp Cyprinus carpio) and goldfish Carassius auratus auratus were produced by artificial spawning. All 3-year-old F1 hybrid males examined were sterile, whereas some F1 hybrid females were fertile and produced eggs after hormonal injection. Backcross progeny were obtained by using intact koi sperm to inseminate eggs from F1 hybrid females; gynogenetic progeny were obtained by inseminating eggs from F1 hybrid females with koi sperm that was genetically inactivated by ultraviolet irradiation. Flow cytometric analysis of DNA content indicated that the backcross progeny were triploid, while the gynogenetic progeny, pure koi, pure goldfish, and F1 hybrids were all diploid. The triploidy of backcross progeny obtained without application of any treatment to the eggs demonstrates that the koi × goldfish hybrid females produce diploid eggs. Received November 11, 2011; accepted February 18, 2012

Inheritance of Predorsal Black Stripe in Black Crappie

Abstract This study presents data on inheritance of the predorsal black stripe in black crappie Pomoxis nigromaculatus. Four progeny groups, obtained by crossing fish with certain phenotypes and of known origin, were investigated. Presence of the black stripe in all fish in two progeny groups, produced by crossing fish with and without the black stripe, indicated dominance of this trait. In two F2 progeny groups, segregations of fish with: without stripe did not differ significantly from the 3:1 Mendelian ratio. It was concluded from the data that the appearance of predorsal stripe in black crappie is under the control of a dominant mutation of one gene (St/st): fish with genotypes StSt and Stst have a stripe, while fish with genotype stst do not possess this trait. Presence or absence of the black stripe was not connected with sex of the fish. This indicates that gene St/st is located in an autosome but not in a sex chromosome. Distribution of fish with stripe in one F2 progeny group with regard to relat...

Gonad Development in Triploid Ornamental Koi Carp and Results of Crossing Triploid Females with Diploid Males

AbstractGonad development in 4-year-old triploid and diploid ornamental koi, a variant of Common Carp Cyprinus carpio, from corresponding heat-shocked and control progenies was investigated. Diploid males were normally mature. Triploid males from heat-shocked progeny demonstrated development of testes typical for triploid fish; triploid males did not release sperm and their testes had a pinkish color and were significantly reduced in size. Diploid females were normally mature and their gonadosomatic indices (GSIs) varied from 7.5% to 30.7% and the mean value was 21.3%. Triploid females had unexpectedly well-developed ovaries, which were filled with fully grown oocytes; their GSIs varied from 4.2% to 30.1% and the the mean value was 17.0%. Four triploid koi females released large quantities (from 260,000 to 394,500 eggs per female) of ovulated eggs after hormonal injection. Eggs from triploid females were fertilized with sperm from normal diploid koi males. Mass mortality of hatched larvae occurred at the ...

Effect of ploidy on scale‐cover pattern in linear ornamental (koi) common carp Cyprinus carpio

The effect of ploidy on scale-cover pattern in linear ornamental (koi) common carp Cyprinus carpio was investigated. To obtain diploid and triploid linear fish, eggs taken from a leather C. carpio female (genotype ssNn) and sperm taken from a scaled C. carpio male (genotype SSnn) were used for the production of control (no shock) and heat-shocked progeny. In heat-shocked progeny, the 2 min heat shock (40° C) was applied 6 min after insemination. Diploid linear fish (genotype SsNn) demonstrated a scale-cover pattern typical for this category with one even row of scales along lateral line and few scales located near operculum and at bases of fins. The majority (97%) of triploid linear fish (genotype SssNnn) exhibited non-typical scale patterns which were characterized by the appearance of additional scales on the body. The extent of additional scales in triploid linear fish was variable; some fish had large scales, which covered almost the entire body. Apparently, the observed difference in scale-cover pattern between triploid and diploid linear fish was caused by different phenotypic expression of gene N/n. Due to incomplete dominance of allele N, triploids Nnn demonstrate less profound reduction of scale cover compared with diploids Nn.