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Sergei Gorshkov Galina Gorshkova Barbara Colorni Hillel Gordin 《Journal of the World Aquaculture Society》2004,35(2):167-177
To produce a monosex female population of European sea bass Dicentrarchus labrax, fry were fed dry diets containing dosages of 12.5, 25, and 50 mg/kg food of either the natural estrogen estradiol-170β(E2) or the synthetic estrogen 17α-ethynylestradiol (EE2) for 60 d starting at 88 d post-hatch (dph). A complete feminization (100%) was achieved in all E2-treated groups at the age of 11 mo (330 dph). All affected fish had ovaries similar in size and histological structure to those of control females. In the E2-treated groups, feminized fish were heavier and longer than untreated controls (males and females combined). In control groups females exhibited significantly higher body weight and total length than males. Untreated females from control groups and females from the group treated with E2 at 12.5 mg/kg food had similar body weight, suggesting that in sea bass growth is related to phenotypic sex. In the Entreated groups, survival rates were similar to those of the control fish. A relatively high percentage of females was obtained in the EE2-treated groups (from 38.6 to 96.5%). However, the gonadal development in these fish was significantly suppressed and a dose-dependent reduction of gonadal sizes was evident. Treatments with the EE2 (12-5, 25, and 50 mg/kg food) resulted in many fish having abnormal (2.9-5.4-39.8%, respectively) and sterile (0.6-6.0-21.6%, respectively) gonads. Effects also included significantly lower weight and shorter length when compared with controls. Furthermore, fish fed with EE2 at the dosage of 50 mg/kg food had high mortality rate. A simple protocol was developed for the complete feminization in sea bass in which the fry (80-100 dph) were fed to satiation two times daily with a diet containing 12.5 me of E2/ks food for a period of 60 d. 相似文献
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Amplified Fragment Length Polymorphism (AFLP) information was used for identification of mango (Mangifera indica L.) cultivars, for studying the genetic relationship among 16 mango cultivars and seven mango rootstocks and for the construction
of a genetic linkage map. Six AFLP primer combinations produced 204 clear bands and on the average 34 bands for each combination.
The average Band-Sharing between cultivars and rootstocks was 83% and 80%, respectively. The average Band-Sharing for mango
is 81%. The probability of obtaining a similar pattern for two different mango cultivars and rootstocks is 6 × 10−3and 2 × 10−3, respectively. A preliminary genetic linkage map of the mango genome was constructed, based on the progeny of a cross between
‘Keitt’ and ‘Tommy-Atkins’. This linkage map consists of 13 linkage groups and covers 161.5 cm defined by 34 AFLP markers.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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Daniel Hillel 《植物养料与土壤学杂志》2009,172(1):5-9
The soil is a vital, complex, and labile medium. To manage it effectively and sustainably, we must strive to understand its attributes, functions, and environmental interactions. Toward this holistic end, we need to overcome traditional disciplinary and institutional barriers so as to promote interdisciplinary cooperation among teams of scientists with different but mutually complementary specialties. Herein, we provide an historical and cultural review of the evolving relationship between humanity and the soil. 相似文献
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分子标记在鸡生物多样性评估中的应用 总被引：1，自引：0，他引：1
品种、群体、家系和个体基因组的DNA变异代表了特定品种内的遗传多样性.对遗传多样性机制研究的深入有助于改变动物的驯化模式,有助于评估群体之间的遗传关系和群体内的遗传变异.另外,该工作也可以确定应用于育种的重要DNA序列.…… 相似文献
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The increasing atmospheric CO2 content (pCO2) is likely to modify the ecosystem functioning including rhizosphere bacteria that are directly dependent on rhizodeposition. This may include alteration of Pseudomonas populations that display phenotypic traits in relation with plant fitness. In the present study, 1228 Pseudomonas strains were isolated from the non-rhizosphere soil, rhizosphere soil and root fractions of perennial grassland systems: Lolium perenne and Molinia coerulea. Both plants were grown under ambient (36 Pa) and elevated (60 Pa) pCO2 in the Swiss Free Air CO2 Enrichment (FACE) system. Pseudomonas spp. were tested for their ability to produce auxin, siderophores and hydrogen cyanide, and to dissimilate nitrate. No effect of root proximity and elevated pCO2 was observed on the proportions of auxin producers. For L. perenne and M. coerulea, siderophore and hydrogen cyanide Pseudomonas producers were stimulated in the root fraction. In contrast lower frequencies of nitrate reducers were observed in the root fraction compared to non-rhizosphere soil. The frequencies of siderophore producers and nitrate dissimilating strains were higher, and those of hydrogen cyanide producers lower, under elevated pCO2 for L. perenne. This alteration of the phenotypic structure of Pseudomonas guild in the root fraction is discussed in relation with the physico-biochemical modifications of the rhizosphere condition via rhizodeposition and environmental changes occurring under elevated pCO2. 相似文献
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Summary Various DNA fingerprint probes were applied to Carica papaya and other Carica species for both identification and genetic analysis.Each of the Carica papaya cultivars is characterized by a specific DNA fingerprints pattern. Various Carica species also have specific patterns which distinguish them from one another. Band sharing levels were used to estimate the relatedness between the various Carica species.Genetic analysis of 11 progeny from a cross between the Carica papaya cultivars 17/82 and 112 suggests that application of DNA fingerprinting to Carica papaya breeding, could make the process more efficient. Genetic analysis of the DNA fingerprint bands revealed no linkage or allelic relationship among the bands analyzed, indicating that these loci are not clustered in the Carica genome. 相似文献
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Weed suppression by cover crops: comparative on‐farm experiments under integrated and organic conservation tillage 
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下载免费PDF全文 Cover crops are increasingly being used for weed suppression and to enhance the sustainability of agro‐ecosystems. However, the suitability of cover crops for weed suppression in integrated and organic conservation tillage systems is still poorly investigated. Therefore, a 2‐year field study at eight sites was conducted to test the weed suppressive potential of six legume‐based cover crops, with the aim to reduce herbicide input or mechanical weed management interventions. In all experiments, cover crops were directly sown after cereals before next year's main crop (grain maize or sunflower). The presence of cover crops caused a 96% to 100% reduction of weed dry matter at the four sites managed under integrated production, while effects were lower at the four sited managed under organic production, ranging from 19% to 87%. Cover crops that covered soil quickly and which produced much dry matter had the best weed suppressive potential. However, their weed suppressing effect was difficult to predict, as it depended on the year of the investigation, experimental site, cover crop species, the speed of soil cover in autumn and the density of the resulting mulch layer in spring. The study demonstrated that cover crops are a useful tool to suppress weeds under integrated and organic conservation tillage practices. Our recommendation for supporting weed management in conservation tillage systems is to use locally adapted cover crops that have rapid establishment, good soil coverage and high dry matter production. However, additional weed management measures are required for reliable weed control under on‐farm conditions. 相似文献
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Laure Weisskopf Renée-Claire Le Bayon Florian Kohler Valérie Page Maryline Jossi Jean-Michel Gobat Enrico Martinoia Michel Aragno 《Soil biology & biochemistry》2008,40(7):1772-1780
Plants are generally assumed to influence the surrounding soil microflora through rhizodeposition. However, the role of rhizodeposits, and especially organic acids, in structuring the bacterial communities is still poorly understood. In this study, we asked the question whether plants differing in organic acid secretion have a different impact on the soil bacterial communities, and if this is the case, to which extent this impact is due to different organic acid concentrations in the rhizosphere. To investigate this question, we compared white lupin and wheat. The former is a high organic acid-secreting species, while the latter secretes only low amounts of carboxylates. We grew the plants in large microcosms including root-free control compartments for one year (replanted every second month) and analyzed the spatio-temporal changes in soil ATP concentrations, as well as in diversity and structure of bacterial communities (using DNA- and RNA-based DGGE) along a root-soil gradient after two, six and twelve month's cultivation. Our results showed: i) that white lupin and wheat differed in their impact on soil ATP concentrations and on the structure of root bacterial communities; ii) that cultivation time was a key factor in explaining the observed differences in all the parameters studied; and iii) that the amounts of organic acids accounted for a significant proportion (15%) of the variability within root active communities. These results indicate that plants influence their associated bacterial communities in a species-specific way and that for communities living in the direct vicinity of roots (rhizoplane-endorhizosphere), a significant part of this influence can be attributed to root-secreted organic acids. 相似文献