shahrouz baradaran noveiri

In this study, the sperm quality indicators of rainbow trout breeders in selected Specific Pathogen Free (SPF) farms of the country were investigated in order to plan the long-term preservation of rainbow trout sperm through cryopreservation and creating a sperm bank in the next phase. Sperm samples from 24 breeders from six selected SPF farms from West-Azerbaijan and Mazandaran provinces were collected and evaluated. The average density of sperm is 7.83 ± 4 billion per milliliter, the average volume of extracted sperm is 9.2 ± 1.6 ml, the average percentage of motility and its duration were 78.7 ± 10.3% and 26.6 ± 4.4 seconds, the average pH was 7.74 ± 0.23 and the fertilization percentage of the samples was as 92.8 ± 1.2%. The results showed that the pH 7.7-7.8 is the most appropriate value for inducing motility and its increasing or decreasing relative to this value causes a decrease in fertilization efficiency. Also, a positive correlation between pH and sperm motility (r = 0.533) and fertility (r = 0.67) was determined. According to the obtained information, the characteristics of the best sperm sample is selected for long-term storage and the creation of a genetically diverse sperm bank and targeted management of rainbow trout reproduction.

Using cryopreservation techniques are so important in conducting brood stock selection programs, species protection, and accessibility to the spermatozoa throughout the year. Normally, in the conventional method in Iran, the formulation based on egg yolk and DMSO has been employed to freeze the sturgeon sperm. In the present study, the MT extender (Modified Tsvetkova’s) which consists of the main components of methanol, sucrose, potassium chloride, and Tris has been used for the preservation of Acipenser stellatus spermatozoa, without using chemical substance DMSO and egg yolk. Our results demonstrated that the frozen sperm had at least 30% motility after one year of storage in nitrogen tank. The results of this research show that this extender could be used to preserve Acipenser stellatus spermatozoa. Since the sperm’s concentration of sturgeon species are similar, the usage of the MT extender can be suggested for other species of the sturgeons.

Siberian sturgeon (Acipenser baerii) grows rapidly in breeding ponds. Gynogenesis is a suitable technique for producing sturgeon female sex. The aim of this study was to establish female sex in Siberian sturgeon using induction of gynogenesis. The sperm of Persian sturgeon (Acipenser persicus) was genetically inactivated by UV radiation at a dose of 8514 J/m2. In this case, sperm with 40% motility were combined with Siberian sturgeon oocytes and in 2°C cold shock for 30 minutes, 10 minutes after activity, gynogenic progeny were created. Fertilization rate was 44.5% (control hybrid 62%) and hatching rate was 19.8% (control hybrid 40.5%). Purely maternal heritability in gynogeneic progeny was confirmed using microsatellite markers. By achieving the biotechnique of sperm production with inactivated DNA of Persian sturgeon, it is possible to prevent the risk of extinction and protect other sturgeon by inducing gynogenesis.

Among vertebrates, most of the fishes are unique for the lack of acrosome in their spermatozoa. The sperm enters the egg through micropyle of the egg. This has facilitated heterologous fertilization in many fishes and led to hybridization and polyploidization. Hybridization is performed both in the nature and domesticated fishes. Today, some of the hybrids have high growth rate than their parents so artificial hybridization be carried out among some economic species. Some of hybrids have high similarity to their parents, so identification and verification of hybrids is impossible. This identification needs both phenotypic (morphometric and meristic) traits and molecular analysis in compared with parents. In this case, the most confidence and the quickest method are molecular markers based on DNA, especially microsatellite markers. It could play an important role in the precise confirmation of fish hybrids.

Through expanding of aquaculture activities, considering of male gamete quality has been increased. Egg fertilization with better quality sperm samples might increase fertilization outputs among all criteria (Fertilization and hatching rates, survival and growth). The quality of gametes involving fertilization relies on extensive factors which could have specific and different effects among species. So, there are many definitions for sperm quality. According to the scientific and technological improvements, the methods for sperm quality assessment have been continuously renewed and assessed through new vision. Study of spermatozoa, is easier than the eggs because of their specific characteristics and ease of sampling and the views of its quality assessment have been developed. In current article, after mentioning to most important fish spermatozoa cellular and morphometric characteristics, the most valuable quality indices and some factors affect them, have been discussed. Respecting to all studies on these indices and quality improvements of each techniques, spermatozoa motility and fertilization indices, still have been recognized as the indices and most reliable and practical indicators for routine sperm quality assessment in fish.

Sperm cryopreservation has been considered as one of the gamete management strategies for artificial reproduction in sturgeons. Bester is a promising fish in sturgeon aquaculture but sperm cryopreservation of this fish had not been studied before. In the present study, changes in motility indices of bester sturgeon spermatozoa were investigated after one year of cryopreservation with two different extenders. The mean percentage of motility, total duration and VSL of samples diluted with E1 extender were 47.57±4.7%, 96.77±6.61s and 125.39±40.81µms-1, respectively and reached to 33.71±5.36%, 102.5±5.24s and 60.84±24.55µms-1, respectively after one-year preservation. Diluted samples with E2 extender showed 41.47±3.06%, 102±9.01s and 110.26±31.19µms-1 for these parameters at sampling day and reduced to 28.51±4.55%, 82.67±10.11s and 52.77±27.6µms-1 after one-year preservation. Results of this study revealed that there are no significant differences among studied motility indices between two extenders (P>0.05). These findings could be regarded as basic information to improve long-term cryopreservation method of bester semen in future.

Hybrids were produced by crossing female Caspian kutum Rutilus frisii kutum with male grass carp Ctenopharyngodon idella. The genome of eight larvae and parents were studied using microsatellite markers for genetic evaluation and verification. After DNA extraction from parent fish and progeny, hybrid heritability of two loci was assessed using two pairs of microsatellite primers. Hybridizied offspring showed as similar banding pattern to that of their maternal parent, without heritability of the paternal genome.

The kutum (Rutilus frisii kutum) is one of the economically valuable species of CaspianSea. Two different races of this fish exist in the Caspian Sea, the spring race and theautumn race. The aims of this study were to analysis the population genetic structure andgenetic diversity among and between populations of these races based on microsatellitemarkers. For this purpose, 100 samples of adult kutum from two regions of Caspian Sea(Anzali Wetland and Shiroud River) were collected. DNA was extracted and 31 pairmicrosatellite primers were used for PCR and 10 made polymorphic patterns. In thisstudy 191 alleles were observed totally. The maximum numbers of alleles (18) were foundin two loci (Ca1 and Ca3) and the minimum number of alleles (2) was found in MFW1locus. The differences between both races were not statistically significant (P>0.05),neither for average number of alleles per locus nor for observed heterozygosities. Thecalculated Fst and Rst between two races was 0.056 and 0.15 which shows that thegenetic difference was significant (P< 0.01). Spring race in MFW1 locus and autumn racein Lid1 locus were at Hardy-Weinberg equation but not in other loci in both races. Thegenetic distance was 0.407 which indicating the greatest genetic distance between the two studied races. The data generated in this study showed that the spring and autumn races of kutum in two region of southern part of Caspian Sea are two independent populations.