Genetic Techniques in Flatfish Culture

1976 ◽  
Vol 33 (4) ◽  
pp. 1088-1093 ◽  
Author(s):  
C. E. Purdom

Selection for improved growth rate does not appear to be feasible in flatfish because the environmental component of variation is very large. Selection for other characters has not been studied. The development of inbred lines, and their use in F1 hybrid production, seems warranted in fish farming if only as a means of avoiding inbreeding depression of fitness. Gynogenesis may be a practical means for accelerating the rate of inbreeding in fish. Induced triploidy is a potentially useful technique in fish culture in that it prevents sexual maturation and limits the depression of growth associated with this. Hybridization is a common phenomenon among fish and can lead to a form of hybrid vigor. Its application in fish culture may be limited by marketing problems where fish are sold under a specific name.

1976 ◽  
Vol 33 (2) ◽  
pp. 316-321 ◽  
Author(s):  
Peter Ihssen

Selective breeding of fish using quantitative genetic techniques is discussed. Fish offer advantages over other livestock for selective breeding procedures because of their relatively high reproductive potential and low reproductive barriers.Maintaining fish stocks in artificial environments can cause undesirable genetic changes such as loss in heterozygosity due to inbreeding and loss in fitness. Methods to minimize inbreeding are given. The study of cross breeds of inbred lines, and hybrids among strains or even species, to produce high levels of heterozygosity and heterosis or hybrid vigor is suggested.


1995 ◽  
Vol 120 (2) ◽  
pp. 292-296 ◽  
Author(s):  
James R. Baggett ◽  
Deborah Kean ◽  
Kathryn Kasimor

Broccoli (Brassica oleracea L. Italica Group) lines with heads borne above the foliage (exserted) favorably for mechanical harvest were crossed with inbred lines with nonexserted heads. Length of the heads, defined as the portion of the plant above the highest major leaf, was ≈50% of the total plant height in short and tall parents and all plants of the F1, F2, and backcross generations. The principal characteristic identified with good head exsertion was long internodes. Internode length was inherited mostly in an additive manner, with some effect of hybrid vigor apparent in the F1, F2, and backcross to the tall parent. Plant height was also inherited in an additive manner. Head weight in the high-exsertion parent was much lower than in the low-exsertion parent. Within each parent and the F1, head weight was greater in plants with longer internodes and greater plant height. In the segregating generations (F2 and backcross), head weight increased with decreasing internode length, indicating that selection for high head exsertion would result in smaller heads and reduced yield.


2020 ◽  
pp. 33-42
Author(s):  
Abdulsamad Noaman ◽  
Zeyad Abdul Hamed ◽  
Ayad Abed

A field experiment was conducted at Northwest of Ramadi .Ten inbred lines by using Line×tester mating method. On spring season 2018 seeds were planted, at an thesis crossing between inbreds and tester was done. On fall season 2018 for crosses and parents using RCBD with three replications to evaluate and estimate heterosis. The results of statistical analysis for these parents and their crosses were highly significant differences for all traits. Genetic analysis shows superiority the inbred KR640 was best for plant height 183.16 cm, number of grain/row 34.34 grain and grain yield 148.43 g .The tester A105 gave high value in grain yield was 145.62 g . The cross (B73 × IK8) gave high leaves area 0.511 cm, no of grain per rows 39.21grain and grain yield 217.05 g. The crosses (B73 × IK8) gave highly positive hybrid vigor to better parent and mid parent for no. of grain per rows was %28.21 and %42.24 grain yield was %79.10 and %81.71. we can conclude the possibility of using superior inbreeds to produce hybrids or use selection for it and produce synthetic varieties.


2019 ◽  
Author(s):  
Yong-Xin Liu

AbstractHeterosis, also known as hybrid vigor or transgression, is the phenomenon wherein an F1 hybrid produced from crossing two cultivars of the same or different species shows superior phenotypes. Heterosis in maize has been found and applied in breeding for more than one hundred years. However, its underlying molecular mechanisms are still poorly understood. To investigate whether small RNAs (sRNAs) participate in the regulation of heterosis, we profiled the sRNA expression patterns in the germ seeds of five inbred lines and theirs three F1 hybrids using high-throughput sequencing technology. The sequencing result show maize sRNAs are enriched in 22-nt length. Nearly 90% of 22-nt small RNA dominated clusters (SRCs) are in repeat regions, which mainly originated from Gypsy and Copia in retrotransposon. About 25% differentially expressed SRCs exist between parents, and hybrid gain almost all differentially expressed 22-nt SRCs. Twenty-four-nt sRNA also enriched in maize, which showed great sequence diversity and overall low expression across the genome. More than half of 24-nt SRCs originate from repeat, and 80% of them come from DNA transposon. Nearly 30% of 24-nt SRCs located in genes or their flanking regions, especially in flanking regions of “lipid metabolic process” and “macromolecule modification” related genes. Several thousands 24-nt SRCs are paternal or maternal specific expressed, and hybrids gain only half of differentially expressed 24-nt SRCs. Hundreds of 24-nt SRCs show high parent or above high parent expression pattern in different hybrids, and them mainly from Tourist, haT, and CACTA in DNA transposon and enrich nearby “tRNA aminoacylation for protein translation” related genes. Also, some 21-nt SRCs show conserved expression pattern in low parent. They were enriched in anti-sense region of some genes, which functions are about oxidative phosphorylation and translation. miRNAs have a global downregulated tendency in hybrids. zma-miR408-5p, zma-miR1432-5p and zma-miR528-5p are significant downregulated in each hybrid, and this phenomenon may cause their target genes more stable and contribute to hybrid vigor. Taken together, our results illustrated that sRNAs may contribute to heterosis at the very early stage of seed germination through repressing of retrotransposon activity, regulation gene activity at gene and genic flanking regions, and promotion some gene expressions by downregulated miRNAs.


2014 ◽  
Vol 4 (1) ◽  
Author(s):  
Janu Dwi Kristianto ◽  
Sunardi Sunardi ◽  
Johan Iskandar

AbstrakDanau merupakan salah satu bentuk ekosistem yang menempati daerah yang relatif kecil pada permukaan bumi dibandingkan dengan habitat laut dan daratan. Bagi manusia kepentingannya jauh lebih berarti dibandingkan dengan luas daerahnya. Sejak tahun 1985 Danau Teluk di Kota Jambi mulai digunakan sebagai lokasi budidaya ikan dengan karamba jaring apung (KJA) dengan jumlah KJA yang beroperasi pada tahun 2012 mencapai + 878 unit dari 64 pembudidaya ikan dan akan meningkat terkait penetapan Propinsi Jambi sebagai salah satu kawasan minapolitan perikanan budidaya guna peningkatan produksi perikanan. Pemanfaatan Danau Teluk sebagai media untuk budidaya ikan di KJA diperlukan upaya untuk mendorong pengelolaan terhadap sumberdaya milik umum ini agar terus bekelanjutan. Kajian mengenai dukung perairan dan pemanfaatan daya Danau Teluk Kota Jambi untuk budidaya ikan sistem KJA bertujuan untuk mengetahui daya dukung Danau Teluk yang digunakan untuk kegiatan budidaya ikan di KJA, bagaimana deskripsi pemanfaatan danau untuk budidaya ikan di KJAyang selama ini dilaksanakan oleh masyarakat sekitar dan merumuskan pola pemanfaatan Danau Teluk untuk budidaya ikan di KJA yang berbasis masyarakat secara berkelanjutan. Hasil penelitian menunjukkan  bahwa  daya dukung perairan Danau Teluk Kota Jambi untuk budidaya ikan di KJA adalah sebesar 517,617 ton ikan  per tahun dengan estimasi jumlah pakan di KJA yang diberikan pada ikan sebanyak 931,710 ton pakan ikan per tahun dengan asumsi kadar total P yang masuk ke perairan danau melalui limbah ikan sebanyak 20 kg P/ ton ikan. Jumlah ideal unit KJA yang seharusnya beroperasi di Danau Teluk berdasarkan penghitungan daya dukung danau sebanyak 862, 695 unit ~ 862 unit. Saat ini jumlah KJA yang beroperasi adalah sebanyak 878 unit sehingga perlu dilakukan pengurangan jumlah sebanyak 16 unit. Pemanfaatan Danau Teluk untuk budidaya ikan oleh masyarakat dilakukan secara sederhana dan jumlah KJA yang terdapat ternyata sudah sedikit melebihi daya dukung perairan jika dilihat dari konsentasi Total P yang ada di perairan. Peningkatan jumlah KJA yang ada di danau perlu mendapat perhatian dari pemerintah dan masyarakat setempat. Pola pemanfaatan danau untuk budidaya ikan berbasis masyarakat yang direkomendasikan adalah dengan mengeluarkan ijin usaha budidaya ikan agar kegiatan budidaya ikan dapat terkendali dan tidak merusak lingkungan, menggunakan pola pemeliharaan ikan dengan jaring ganda sehingga biaya operasional lebih efisien dan produksi ikan dapat ditingkatkan, membuat manajemen pakan dalam penerapan budidaya ikan dalam KJA, meningkatkan SDM pembudidaya ikan dan mengaktifkan kembali kelompok pembudidaya ikan sehingga koordinasi antar pembudidaya, pemerintah dan stakeholder terkait dapat terjalin serta pengaturan tata ruang KJA.Kata Kunci : pemanfaatan danau, daya dukung, Danau Teluk, budidaya ikan KJA, berbasis masyarakatAbstracLake is one of ecosytem form than occupies a relative small area on the surface of the earth as compared to sea and land habitats. For humans, utilization  is more important than the expanse of lands. Since 1985, Teluk Lake began to be used as the location of fish cultivation with floating net cage culture (FNCC). The number of FNCC in 2012 reached ± 878 unit of 64 fish farmers and it will increase related to determination of Jambi Province as one of Minapolitan fishery cultivation in order to increase fish production. Utilization of Teluk Lake as media for fish cultivation on floating cage is necessary to encourage the management of common resources is to be kept sustainable.  Studies on carrying capacity and utilization of Teluk Lake Jambi City for community-based fish cultivation on FNCC aims to know how the use of this lake that have been implemented by the local community and to find out patterns of Teluk Lake utilization to fish culture in floating cage sustainable community-based  and to find out how the carrying capacity Teluk lake that used to fish farming activities in floating cage. Methods used in this study is qualitative and quantitative methods with a descriptive approach. 1Result showed that carrying capacity of Teluk lake for fish farming in FNCC is equal  517,617 tons of  fish per year with estimate amount of feed given to fish in floating cage is as many as  931,710 ton per year assuming total P were entered into the lake through fish waste as much 20 k P/ton of fish. Ideal number of floating cage based on lake  carrying capacity accounting should be 862,695 unit ~ 862 unit. Operating floating cage currently  is  878 unit so that it is necessary reduction in the amount of 16 unit and if they want to add a new one, it should be an improvement or replacement of existing floating cage at lake. Utilization of Teluk Lake for fish farming is done simple by local communities and number of existing floating cage already slightly exceed the carrying capacity of lake if related from existing concentration of total P in water. The increasing amount of floating cages in lake should be attend from goverment and local communities, so it is necessary to manage the use of lake for fish cultivation. Pattern of lake utilization for fish farming  based- community ist recommended to issue a business licence, in order to control fish farming activity, and not damage the environment, using growt out pattern by double nets so that more efficient operating cost and fish production can be increased, making management of feed in fish farming at floating cage, develop capability of human resouces, activate again POKDAKAN so coordination between farmers, goverment and stakeholder can be build and layout arrangement FNCC. Keywords : Lake utilization, carrying capacity,Teluk Lake, fish culture on floating cage,community based


1974 ◽  
Vol 19 (3) ◽  
pp. 273-289 ◽  
Author(s):  
W. K. Al-Murrani ◽  
R. C. Roberts

SUMMARYA line of mice, at its limit to selection for high body weight did not decline in performance over 11 generations of random mating, neither did it respond when selection was renewed. The experiment tested a method of improving body weight by a scheme which had earlier increased litter size under similar circumstances. The scheme was to derive partially inbred lines from the plateaued line, to select during inbreeding and, finally, to cross the best inbreds. Body weight was not increased, but the study allowed further examination of the residual genetic variance in the line.During inbreeding, the inbred lines became clearly differentiated in body weight, proving that loci controlling body weight had not become fixed. There was also a significant response to selection for a lower body weight during inbreeding. The pattern of results suggested the segregation of recessive genes, detrimental to high body weight but which selection had become inefficient at removing. A genetic model compatible with the results accommodated several such recessives, perhaps as many as 10, each with an effect of about two-thirds of a standard deviation (or some equivalent combination of gene number and effect), and at frequencies of around 0·2. Nevertheless, the total improvement in body weight to be gained by their elimination was only half a gram, or less than 2 %. Thus, substantial genetic effects can occur at individual loci despite trivially low heritabilities and negligible potential gains.


Data in Brief ◽  
2016 ◽  
Vol 6 ◽  
pp. 229-237 ◽  
Author(s):  
Kazutaka Kawamura ◽  
Takahiro Kawanabe ◽  
Motoki Shimizu ◽  
Keiichi Okazaki ◽  
Makoto Kaji ◽  
...  

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