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1.
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
2.
O'Connell MJ Bachilo SM Huffman CB Moore VC Strano MS Haroz EH Rialon KL Boul PJ Noon WH Kittrell C Ma J Hauge RH Weisman RB Smalley RE 《Science (New York, N.Y.)》2002,297(5581):593-596
Fluorescence has been observed directly across the band gap of semiconducting carbon nanotubes. We obtained individual nanotubes, each encased in a cylindrical micelle, by ultrasonically agitating an aqueous dispersion of raw single-walled carbon nanotubes in sodium dodecyl sulfate and then centrifuging to remove tube bundles, ropes, and residual catalyst. Aggregation of nanotubes into bundles otherwise quenches the fluorescence through interactions with metallic tubes and substantially broadens the absorption spectra. At pH less than 5, the absorption and emission spectra of individual nanotubes show evidence of band gap-selective protonation of the side walls of the tube. This protonation is readily reversed by treatment with base or ultraviolet light. 相似文献
3.
Specificity and stability in topology of protein networks 总被引：4，自引：0，他引：4
Molecular networks guide the biochemistry of a living cell on multiple levels: Its metabolic and signaling pathways are shaped by the network of interacting proteins, whose production, in turn, is controlled by the genetic regulatory network. To address topological properties of these two networks, we quantified correlations between connectivities of interacting nodes and compared them to a null model of a network, in which all links were randomly rewired. We found that for both interaction and regulatory networks, links between highly connected proteins are systematically suppressed, whereas those between a highly connected and low-connected pairs of proteins are favored. This effect decreases the likelihood of cross talk between different functional modules of the cell and increases the overall robustness of a network by localizing effects of deleterious perturbations. 相似文献
4.
Polyansky OL Császár AG Shirin SV Zobov NF Barletta P Tennyson J Schwenke DW Knowles PJ 《Science (New York, N.Y.)》2003,299(5606):539-542
The spectrum of water vapor is of fundamental importance for a variety of processes, including the absorption and retention of sunlight in Earth's atmosphere. Therefore, there has long been an urgent need for a robust and accurate predictive model for this spectrum. In our work on the high-resolution spectrum of water, we report first-principles calculations that approach experimental accuracy. To achieve this, we performed exceptionally large electronic structure calculations and considered a variety of effects, including quantum electrodynamics, which have routinely been neglected in studies of small many-electron molecules. The high accuracy of the resulting ab initio procedure is demonstrated for the main isotopomers of water. 相似文献
5.
Cruz-Migoni A Hautbergue GM Artymiuk PJ Baker PJ Bokori-Brown M Chang CT Dickman MJ Essex-Lopresti A Harding SV Mahadi NM Marshall LE Mobbs GW Mohamed R Nathan S Ngugi SA Ong C Ooi WF Partridge LJ Phillips HL Raih MF Ruzheinikov S Sarkar-Tyson M Sedelnikova SE Smither SJ Tan P Titball RW Wilson SA Rice DW 《Science (New York, N.Y.)》2011,334(6057):821-824
The structure of BPSL1549, a protein of unknown function from Burkholderia pseudomallei, reveals a similarity to Escherichia coli cytotoxic necrotizing factor 1. We found that BPSL1549 acted as a potent cytotoxin against eukaryotic cells and was lethal when administered to mice. Expression levels of bpsl1549 correlate with conditions expected to promote or suppress pathogenicity. BPSL1549 promotes deamidation of glutamine-339 of the translation initiation factor eIF4A, abolishing its helicase activity and inhibiting translation. We propose to name BPSL1549 Burkholderia lethal factor 1. 相似文献
6.
Pan W Choi SC Wang H Qin Y Volpicelli-Daley L Swan L Lucast L Khoo C Zhang X Li L Abrams CS Sokol SY Wu D 《Science (New York, N.Y.)》2008,321(5894):1350-1353
The canonical Wnt-beta-catenin signaling pathway is initiated by inducing phosphorylation of one of the Wnt receptors, low-density lipoprotein receptor-related protein 6 (LRP6), at threonine residue 1479 (Thr1479) and serine residue 1490 (Ser1490). By screening a human kinase small interfering RNA library, we identified phosphatidylinositol 4-kinase type II alpha and phosphatidylinositol-4-phosphate 5-kinase type I (PIP5KI) as required for Wnt3a-induced LRP6 phosphorylation at Ser1490 in mammalian cells and confirmed that these kinases are important for Wnt signaling in Xenopus embryos. Wnt3a stimulates the formation of phosphatidylinositol 4,5-bisphosphates [PtdIns (4,5)P2] through frizzled and dishevelled, the latter of which directly interacted with and activated PIP5KI. In turn, PtdIns (4,5)P2 regulated phosphorylation of LRP6 at Thr1479 and Ser1490. Therefore, our study reveals a signaling mechanism for Wnt to regulate LRP6 phosphorylation. 相似文献
7.
Zhang GF Maudens KE Storozhenko S Mortier KA Van Der Straeten D Lambert WE 《Journal of agricultural and food chemistry》2003,51(27):7872-7878
A procedure involving chemical conversion of all forms of folate present in plant material into para-aminobenzoic acid (PABA) and a liquid chromatographic-fluorimetric determination with on-line postcolumn derivatization is reported. All folates are cleaved with liberation of PABA by hydrogen peroxide followed by acid hydrolysis using concentrated hydrochloric acid (37%) at 110 degrees C for 6 h. The reaction yield for individual folates conversion to PABA ranged from 44.4 to 97.3%. PABA could be determined sensitively by on-line postcolumn derivatization with fluorescamine, the detection limit for PABA being 3.02 nM. On the basis of this principle, a method for the determination of total folate in plant material, including a purification step on an affinity column, is presented, which offers a sufficient sensitivity and selectivity for routine analysis of total folate in natural samples. The total folate contents of tomatoes, carrots, white cabbage, and spinach were determined, and the results were quite comparable to the data reported. The recovery of PABA and the comparison of total folate analysis in spinach on different occasions (over 6 months) are also reported. The method is reliable, universal for all folates, including polyglutamate and monoglutamate forms, and eliminates the need for a deconjugation step and multiple conversion reactions. 相似文献
8.
de Jager et al. (Reports, 24 June 2011, p. 1551) concluded that mussels Lévy walk. We confronted a larger model set with these data and found that mussels do not Lévy walk: Their movement is best described by a composite Brownian walk. This shows how model selection based on an impoverished set of candidate models can lead to incorrect inferences. 相似文献
9.
Indicators of success for smart law enforcement in protected areas: A case study for Russian Amur tiger (Panthera tigris altaica) reserves 
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下载免费PDF全文 Michiel H. H. HÖTTE Igor A. KOLODIN Sergei L. BEREZNUK Jonathan C. SLAGHT Linda L. KERLEY Svetlana V. SOUTYRINA Galina P. SALKINA Olga Y. ZAUMYSLOVA Emma J. STOKES Dale G. MIQUELLE 《Integrative zoology》2016,11(1):2-15
Although considerable conservation resources have been committed to develop and use law enforcement monitoring and management tools such as SMART, measures of success are ill‐defined and, to date, few reports detail results post‐implementation. Here, we present 4 case studies from protected areas with Amur tigers (Panthera tigris altaica) in Russia, in which indicators of success were defined and evaluated at each. The ultimate goal was an increase in tiger numbers to 1 individual/100 km2 at each site. We predicted that improvements in law enforcement effectiveness would be followed by increases in prey numbers and, subsequently, tiger numbers. We used short‐term and long‐term indicators of success, including: (i) patrol team effort and effectiveness; (ii) catch per unit effort indicators (to measure reductions in threats); and (iii) changes in target species numbers. In addition to implementing a monitoring system, we focused on improving law enforcement management using an adaptive management process. Over 4 years, we noted clear increases in patrol effort and a partial reduction in threats. Although we did not detect clear trends in ungulate numbers, tiger populations remained stable or increased, suggesting that poaching of tigers may be more limiting than prey depletion. Increased effectiveness is needed before a clear reduction in threats can be noted, and more time is needed before detecting responses in target populations. Nonetheless, delineation of concrete goals and indicators of success provide a means of evaluating progress and weaknesses. Such monitoring should be a central component of law enforcement strategies for protected areas. 相似文献
10.
Maryam Zolghadr Sergei Zuyev 《Journal of Agricultural, Biological & Environmental Statistics》2016,21(4):663-683
The paper develops methods to construct a one-stage optimal design of dilution experiments under the total available volume constraint typical for biomedical applications. We consider various design criteria based on the Fisher information both in Bayesian and non-Bayesian settings and show that the optimal design is typically one-atomic meaning that all the dilutions should be of the same size. The main tool is variational analysis of functions of a measure and the corresponding steepest descent-type numerical methods. Our approach is generic in the sense that it allows for inclusion of additional constraints and cost components, like the cost of materials and of the experiment itself. 相似文献