چكيده انگليسي :
In order to introduce a new sturgeon hybrid to aquaculture industry, the possibility of hybrid production by crossing between Siberian and Persian sturgeons and its comparison with its pure parents using morphometric, molecular, cytogenetic and growth performance were conducted. For this purposes eggs and sperms of two pairs of Persian and Siberian sturgeon were collected and reciprocal crosses with 4 treatments were conducted. In treatment 1, Persian sturgeon as control (male and female of Persian sturgeon), treatment 2 (as type I hybrid) from crosses of male Persian sturgeon with eggs of female Siberian sturgeon in treatment 3 (type II hybrid) using crosses between male Siberian sturgeon and female Persian sturgeon and finally treatment 4 by crossing male and female of Siberian sturgeon were used.For each treatment 200 gr. of eggs were fertilized with one ml. of sperm and morphological, meristic parameters of parents and offspring were recorded. For growth comparison of fingerlings of control and hybrids in 3 different phases were measured. In phase (I), larvae rearing from 46 mg. up to 6600 mg. were conducted for a period of 10 weeks. Samples were collected once every two weeks and biological parameters were recorded.In rearing phase II for a period of 330 days, growth comparison were conducted for fish from 6.5 gr. to 750gr. and biological parameter were recorded once every month, where daily growth rate (gr./day), FCR, Specific growth coefficient (percentage per day), increase of body weight, food efficiency and protein efficiency ration were analyzed.In rearing phase (III), from 600 gr. to 2000 gr. for a period of 43 weeks, similar to phase (II) all biological parameters were analyzed, where 26 morphometric and meristic parameters of pure and hybrid parents and offspring were compared both for individual and ratio status of parameters.For genetic analysis and variation between control and hybrid specimens the microsatellite analysis were conducted. For this purposes, genomic DNA were extracted from fin tissues of brood stocks and fingerlings and 10 pairs of specific primers (Afug 56, Afug 63, Afug 241, Afug 229, OX 27, Afug 686, Afug 195, Afug 12, IS 68 and Afug 160) were used. Then PCR Products were electrophoresed on 6% polyacrylamide gel and then were stained with Nitrate silver and alleles were evaluated based on its length (base pair).Cytogenetic analysis and number of chromosome of control fish and hybrid were compared using white blood cell culture method and chromosome spread of parents as well as offspring were prepared by Gimsa staining and were visualized under light microscope.For sexual gonad development, laparoscopic method with light camera (Model M-CAM 1700) were used to differentiate 34 pieces of control and hybrid fish and gonad status of ovary and testis were analyzed.In present investigation the results indicate that, in phase (I) of larvae culture, a significant differences were observed after 10 weeks of feeding (p≤ 0.05) in hybrid and control groups. Maximum growth rate were observed in Siberian sturgeon larvae, followed by type I hybrid, type II hybrid and Persian sturgeon larvae.In phase (II) , growth rate of Persian sturgeon were lower than Siberian sturgeon. For period of 330 days of rearing periods, the control Siberian sturgeon had 1.4gr. weight increment per day, while Persian sturgeon had only1. gr./day. However the hybrid type (I) had an average daily growth of 1.5gr/day and lower growth performance were observed in type II hybrid with daily growth of 1.5 gr./day.In phase (III), growth rates were varied at different age group. The daily growth rate of Siberian sturgeon was 4.5gr/day, while is control Persian sturgeon was 2.6 gr/day. The Siberian sturgeon within 47 weeks of rearing grown from 655 gr. to 2016 gr., however Persian sturgeon for the same period reached from Siberian sturgeon with male’s Persian sturgeon had higher type II hybrid showed opposite results for the same growing period and reached from 640 gr. to 1680 gr.In conclusion of growth performance can be stated that the hybrid from crosses between female Siberian sturgeon with male Persian sturgeon presented highest growth rate in comparison to control hybrid. This excellent achievement can be considered as a big step toward sturgeon aquaculture for meat and Caviar production.In analysis of morphometric characters 26 parameters were investigated which in 18 parameters showed significant differences (p≤ 0.05) which indicate clear distinguish able of hybrid performance in compare with parents where Siberian sturgeon has longer snout compare to Persian sturgeon and its size are intermediate in hybrids. In relative ratio of characters, out of 9 characters totally 7 characters showed significant differences (p≤ 0.05).In molecular analysis using microsatellite primers totally 400 DNA samples of hybrid as well as the control fish were investigated. Totally 784 allele were detected in which 363 alleles were belong to control fish and 421 alleles in hybrid. In this study, 19 alleles with different sizes were observed in hybrids rang from (120bp) in Aox27 primers (400bp) in AFUG229 primers. In comparing of all primers, the primer AFUG160 and AFUG195 with 2 alleles and primer AFUG686 with 7 alleles showed the minimum and maximum allele numbers.The banding patterns were monomorphic in 66 loci of control fish and 65 loci of hybrids, and in 77 loci of control fish and 73 loci of hybrids were diploid in 9 loci of control fish and 12 loci of hybrid fish were tetraploid, in one locus of control samples and 3 hybrid samples were pentaploid and finally within 10 pairs of primers 7 sets were disomic, 3 primers (Afug241, Afug686, Aox27) were tetraploid and 6 primers of (Afug63, Aox27, Afug688, Afug12, Is68, Afug160) showed excellent allele heritability which indicate the high efficiency of microsatellite techniques. In evaluation of the status of gonad development as well as determination of sexual stages laprascopic method indicated that out of 9 samples of Persian sturgeon (4 females and 5 male) were in stage of 2 & 3 gonad development. Out of 8 Siberian sturgeon (4 males+4 females) stage 2, 3, 4 were detected. In 7 gonad samples of hybrid (Female Persian and Male Siberian) totally 5 male and 2 female were observed at stage 3 and 4 gonad development. In analysis of 10 samples of type II hybrid (female Siberian × male Persian) 3 female, 6 males and 1 deformetic were observed.Cytological studies on 30 metaphase palate from 6 fish samples showed that the number of chromosome in hybrid are as same as parents 2n=250±10 where all control and hybrids similar to its parents showed 240 chromosome.In conclusion, It can stated that, this study successfully introduced a new sturgeon hybrid for sturgeon farming both for meat and caviar production. Considering the common name of sturgeon parents used for production this hybrid, we call this hybrid as (Siper) where Si instant for Siberian sturgeon and Per comes from Persian sturgeon
