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51.
基于遗传算法的思想,研究并提出了凸多边形面积最小的凸四边形包围盒生成算法。该算法简单,速度快,效果显著。实际应用表明了该算法的有效性与实用性。 相似文献
52.
Carol Nelson Mazur D. A. Higgs E. Plisetskaya B. E. March 《Fish physiology and biochemistry》1992,10(4):303-313
Juvenile chinook salmon of three strains responded to inclusion of 28.7% of gelatinized starch in the diet with different degrees of reduction in growth rate and feed efficiency relative to control fish of the respective strains fed a low-starch, high-lipid diet of similar protein (46%) and estimated metabolizable energy content (16 mJ/kg). The productive protein value of the diet was not reduced to the same extent by the high intake of starch. Carcasses of fish fed the high-starch diet contained higher concentrations of protein and lower concentrations of lipid than control fish. The accumulation of liver glycogen in response to the high-starch diet differed among strains. Glucose tolerance curves also varied among strains but were poorly correlated with plasma concentrations of insulin. Tolerance to glucose loading was improved in fish previously fed the high-starch diet. 相似文献
53.
The shrimp industry, including its culture and feed sectors, exhibited steady growth over the years with a reduced cost–benefit ratio due to increasing production costs attributed mainly to enhanced feed costs. The unsustainable availability and rapid increase in fishmeal cost have forced the aquafeed sector to reduce dietary inclusion levels. The filamentous fungus, Aspergillus niger plays an important role in utilising plant protein sources for formulating cost-effective shrimp feed. A. niger has been reported to produce numerous hydrolytic enzymes to degrade the limiting factors of plant proteins such as antinutrients and fibre fractions. This fungus enhanced not only the quantity but also the quality of proteins and amino acids, especially methionine and lysine. Likewise, it also increased the availability of soluble minerals, particularly phosphorous, by degrading the phytic-phosphorus, thereby helping to replace dietary fishmeal up to 80% in penaeid shrimps. Consequently, this fungus could reduce feed formulation cost significantly. However, the mycotoxins produced by this fungus pose difficulties during large-scale fermentation, and its implications on the workers and environment cast doubt about its efficacy and utility. However, recent developments indicate that A. niger could be an alternative choice in reducing the pressure on fishmeal demand by enhancing the nutrient utilization of plant-based materials leading to the formulation of, cost-effective feeds that can sustain shrimp culture and production in the future. 相似文献
54.
实数型遗传算法的研究 总被引：1，自引：2，他引：1
在引入实数型遗传算法的基础上,对遗传算法的关键问题交叉和变异操作进行了深入的研究,提出了几种新颖而实用的交叉和突异操作方法。同时,对需编码的传统的二进制型遗传算法和无需编码的实数型遗传算法进行了简要的比较,阐述了实数型遗传算法的优越性。 相似文献
55.
Tanzania demarcated three prawn fishing zones along its coast to spread fishing pressure and help the prawn fishery to recover. However, it is unknown whether the demarcated zones correspond to the genetic stock structure of the world's most commercially important prawn, the giant tiger prawn (Penaeus monodon). Thus, this study used partial mitochondrial control region sequences (534 base pairs) to test the hypotheses that (1) giant tiger prawns in Tanzania's demarcated prawn fishing zones are a single stock and (2) the giant tiger prawns on the Tanzanian coast experienced a recent demographic expansion. The sequences showed high haplotype diversity (h = 0.998–1.0) and low nucleotide diversity (θπ = 1.89%–2.24%). The neutrality test and mismatch analysis showed that the hypothesis of recent demographic expansion could not be rejected. The analysis of molecular variance revealed low and insignificant fixation indices between the zones (FST = 0.00025, p > 0.05; ΦST = −0.00027, p > 0.05), suggesting that the three demarcated fishing zones constitute a single stock and that fishers may be targeting the same stock. Furthermore, it was discovered that Zone 2 has the potential to replenish depleted areas; thus, it should be prioritised in future conservation planning. 相似文献
56.
Mitsuyuki Tomiyoshi Yasuo Yasui Takanori Ohsako Cheng-Yun Li Ohmi Ohnishi 《Breeding Science》2012,62(3):241-247
Fagopyrum homotropicum Ohnishi is a self-pollinating wild buckwheat species indigenous to eastern Tibet and the Yunnan and Sichuan Provinces of China. It is useful breeding material for shifting cultivated buckwheat (F. esculentum ssp. esculentum Moench) from out-crossing to self-pollinating. Despite its importance as a genetic resource in buckwheat breeding, the genetic variation of F. homotropicum is poorly understood. In this study, we investigated the genetic variation and phylogenetic relationships of the diploid and tetraploid forms of F. homotropicum based on the nucleotide sequences of a nuclear gene, AGAMOUS (AG). Neighbor-joining analysis revealed that representative individuals clustered into three large groups (Group I, II and III). Each group contained diploid and tetraploid forms of F. homotropicum. We identified tetraploid plants that had two diverged AG sequences; one belonging to Group I and the other belonging to Group II, or one belonging to Group II and the other belonging to Group III. These results suggest that the tetraploid form originated from at least two hybridization events between deeply differentiated diploids. The results also imply that the genetic diversity contributed by tetraploidization of differentiated diploids may have allowed the distribution range of F. homotropicum to expand to the northern areas of China. 相似文献
57.
利用113对SSR多态性引物研究了来源比较广泛的26个自选爆裂玉米自交系的遗传多样性，并初步进行了杂种优势群划分．结果表明，供试自交系间共检测出301条带，每个位点的等位基因数为1～3个，多态性信息量为0．068～0．217，自交系间的遗传距离为0．1483～0．5240；供试自交系可划分为8个杂种优势群，分群结果与杂交组合的组配效果相吻合，高优势组合的亲本均属于不同的优势类群，而在类群内未组配出优势组合．SSR标记可以用于研究爆裂玉米自交系的种质基础． 相似文献
58.
Alessandro Infantino Mohamed Kharrat Luca Riccioni Clarice J. Coyne Kevin E. McPhee Niklaus J. Grünwald 《Euphytica》2006,147(1-2):201-221
Summary Soil-borne fungal diseases are among the most important factors, limiting the yield of grain legumes in many countries worldwide. Root rot, caused by Aphanomyces euteiches, Rhizoctonia solani, Fusarium solani and wilt, caused by several formae speciales of Fusarium oxysporum are the most destructive soil-borne diseases of pea, chickpea, lentil, fababean and lupin. The most effective control of these diseases is achieved through the use of resistant varieties. In this paper, recent advances in conventional and innovative screening methods for disease resistance are presented. Many grain legume accessions, which are maintained in national and international germplasm collections, have been evaluated for disease resistance and numerous resistant varieties have been released following incorporation of identified resistance genes from these sources. Recent identification of molecular markers tightly linked to resistance genes has greatly enhanced breeding programs by making marker assisted selection (MAS) possible and allowing the development of varieties with multiple disease resistance. Progress in the understanding of the biology of soil-borne fungal pathogens of grain legumes is also reviewed with particular reference to the genetic structure of their populations, diagnosis and host–pathogen interaction. 相似文献
59.
OBJECTIVE: To determine whether the rcd-1 mutation causing progressive retinal atrophy (PRA) in Irish Setters is in the Australian breeding population. METHOD: DNA samples were tested for the mutation using the Polymerase Chain Reaction and specific primer nucleotides to amplify the phosphodiesterase gene followed by restriction enzyme cleavage and fragment size determination. RESULTS: No mutant alleles were found in 38 Irish Setters, representing over 80% of all major breeding stock in five Australian states. CONCLUSIONS: It is likely that the Australian population of Irish Setters is free of the rcd-1 form of PRA. 相似文献
60.
J. Armengol A. Vicent M. León M. Berbegal P. Abad-Campos J. García-Jiménez 《Plant pathology》2010,59(1):179-185
Genetic diversity was studied in a population of 24 isolates of Rosellinia necatrix obtained from Cyperus esculentus and 16 from other hosts by means of mycelial compatibility groups (MCGs) and inter-simple sequence repeat (ISSR) techniques. All isolates obtained from C. esculentus belonged to a unique MCG, irrespective of their geographical origin or year of isolation, and were incompatible with the isolates from other hosts. ISSR analysis gave results which were in agreement with the MCG determination; selected ISSR primers grouped a subset of eight representative isolates from C. esculentus in a unique cluster. The homogeneity found within the population of R. necatrix from C. esculentus in Valencia province could suggest that the pathogen was introduced recently and has spread further via infected tubers inadvertently used as propagating material, as well as by cull tubers swept away by irrigation water. 相似文献