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排序方式: 共有270条查询结果,搜索用时 31 毫秒
71.
Gicelle Maria Farias da Silva Maria Auxiliadora Pantoja Ferreira Esther Iris Christina Freifrau von Ledebur & Rossineide Martins da Rocha 《Aquaculture Research》2009,40(7):798-803
The aim of this work is to correlate the histological gonad analysis of adult male Macrobrachium amazonicum of a wild population with morphotypes identified in populations reared in earthen ponds. A total of 500 adult male specimens were collected in the Mosqueiro Island, Municipality of Belém, State of Pará, Brazil. The animals were classified on the basis of body and cheliped colour, second right cheliped spination, total length, cheliped length and weight. The gonads of each morphotype were fixed, processed by histological techniques and stained with haematoxylin and eosin. All four morphotypes, translucent claw (TC), cinnamon claw (CC), green claw 1 (GC1) and green claw 2 (GC2), were identified in the wild population, indicating the same population structure described for cultured animals. The M. amazonicum testes are composed of multiple lobes. The TC gonads showed a population of germ cells in the eccentric portion of the seminiferous tubule and few spermatozoa in the central region. Cinnamon claw males exhibited a large cell population with intense meiotic activity and sparse spermatozoa. Regardless of the different external morphologies of GC1 and GC2, no histological differences were found in their gonads; both had a large number of gametes and similar spermatogenic cell population. Despite the external morphological evidences of the four morphotypes, the histological criteria indicate the existence of only three morphotypes: TC, CC and green claw (GC). 相似文献
72.
Konrad Dabrowski Murat Arslan Jacques Rinchard Maria Esther Palacios 《Journal of the World Aquaculture Society》2008,39(2):174-183
Growth, plasma steroids, and the appearance of gonads (histology and gonadosomatic index) were followed in South American catfish (surubim, Pseudoplatystoma sp.) raised in captivity in the aquaculture facility at The Ohio State University, Columbus, Ohio, USA, from 2003 until 2006. Broodstock growth showed a great individual variation and it did not seem sex dependent. The levels of 11‐ketotestosterone were high in males during the reproductive season. Three out of six females spawned after receiving two doses of carp pituitary extract (0.5 and 5 mg/kg) at 11‐h intervals. Fertilization was performed in only one female in February 2006. Egg size was 0.73 ± 0.06 mm in diameter at stripping. Two males released sperm, and it was used for fertilization. Sperm concentrations were 24 × 109 and 15.5 × 109 spermatozoa/mL in Male 1 and Male 2, respectively, and viability was confirmed after activation in 0.3% NaCl. Embryo survival at 9 h after fertilization was 44 and 23% for Male 1 and Male 2, respectively. Embryos hatched 15 h after fertilization. Larvae were 3.53 ± 0.09 mm in length at hatching and were successfully raised (72% survival after 2 wks) using live brine shrimp nauplii. 相似文献
73.
de Villeneuve VW Dullens RP Aarts DG Groeneveld E Scherff JH Kegel WK Lekkerkerker HN 《Science (New York, N.Y.)》2005,309(5738):1231-1233
Impurities affect the nucleation, growth, and structure of crystals. Here we report the effect of large, spherical, polymethylmethacrylate impurities on the crystal growth of monodisperse, hard, polymethylmethacrylate colloids in a density- and optically matching apolar solvent mixture. Crystal growth, initiated at the bottom of the sample, was studied by imaging sequences of two-dimensional xy slices in the plane of the impurity's center with a laser scanning confocal microscope. Impurities form the center of grain boundaries, and a single fluid particle layer around the impurity persists in all cases. The growth rate sensitively depends on the impurity's size. Crystal growth is inhibited to a greater extent near smaller impurities, pointing to local crystal frustration induced by the curvature of the impurity. 相似文献
74.
Rauch A Thiel CT Schindler D Wick U Crow YJ Ekici AB van Essen AJ Goecke TO Al-Gazali L Chrzanowska KH Zweier C Brunner HG Becker K Curry CJ Dallapiccola B Devriendt K Dörfler A Kinning E Megarbane A Meinecke P Semple RK Spranger S Toutain A Trembath RC Voss E Wilson L Hennekam R de Zegher F Dörr HG Reis A 《Science (New York, N.Y.)》2008,319(5864):816-819
Fundamental processes influencing human growth can be revealed by studying extreme short stature. Using genetic linkage analysis, we find that biallelic loss-of-function mutations in the centrosomal pericentrin (PCNT) gene on chromosome 21q22.3 cause microcephalic osteodysplastic primordial dwarfism type II (MOPD II) in 25 patients. Adults with this rare inherited condition have an average height of 100 centimeters and a brain size comparable to that of a 3-month-old baby, but are of near-normal intelligence. Absence of PCNT results in disorganized mitotic spindles and missegregation of chromosomes. Mutations in related genes are known to cause primary microcephaly (MCPH1, CDK5RAP2, ASPM, and CENPJ). 相似文献
75.
76.
Zabalza A González EM Arrese-Igor C Royuela M 《Journal of agricultural and food chemistry》2005,53(19):7486-7493
The inhibition of branched-chain amino acid (BCAA) biosynthesis was evaluated in pea plants in relation to the ability for induction of fermentative metabolism under aerobic conditions. Chlorsulfuron and imazethapyr (inhibitors of acetolactate synthase, ALS, EC 4.1.3.18) produced a strong induction of pyruvate decarboxylase (PDC, EC 4.1.1.1) and alcohol dehydrogenase (ADH, EC 1.1.1.1) activities and a lesser induction of lactate dehydrogenase (LDH, EC 1.1.1.27) and alanine aminotransferase (AlaAT, EC 2.6.1.2) activities in roots. Inhibition of the second enzyme of the BCAA biosynthesis (ketol-acid reductoisomerase, KARI, EC 1.1.1.86) by Hoe 704 (2-dimethylphosphinoyl-2-hydroxyacetic acid) and CPCA (1,1-cyclopropanedicarboxylic acid) enhanced fermentative enzyme activities including PDC, ADH, and AlaAT. Fermentative metabolism induction occurring with ALS- and KARI-inhibitors was related to a higher expression of PDC. In the case of KARI inhibition, it is proposed that fermentation induction is due to an inhibition of ALS activity resulted from an increase in acetolactate concentration. Fermentative metabolism induction in roots, or at least ethanolic fermentation, appeared to be a general physiological response to the BCAA biosynthesis inhibition. 相似文献
77.
Dionisio Lidia P. C. Garcia-Rosado Esther Lopez-Cortes Lourdes Castro Dolores Borrego Juan J. 《Water, air, and soil pollution》2002,138(1-4):319-334
Three microbiological criteria (European Economic Community,World Health Organization/United Nations Environment Programand European Union) for water quality have been comparativelyevaluated in a resort zone of southern Portugal, located atthe Ria Formosa (Algarve). The results obtained in this studysuggest that the three compared directives adequatelyclassified the bathing zones according to their fecalpollution level. However, none of the directives establish asanitary classification of the recreational use of the bathingzones. By the use of the Cumulative Contamination Indexapplied in this study, classification based on both the levelof fecal pollution and on the sanitary condition of thebathing zones has been achieved. The application of this newapproach to the monitoring of bathing waters allows us topropose a new criterion of water quality based on thecoliphage levels (Ph80 = 300 pfu 100 mL-1 and Ph95 = 2000 pfu 100 mL-1) for inclusion in the newwater quality regulations. Coliphages have been shown to havea close correlation with the presence of pathogenic microorganisms, and with the fecal pollution levels of recreational seawaters. However, none of the microbial indicatorstested ensured detection of pathogen presence. 相似文献
78.
Pérez-Corona María Esther Pérez-Hernández María del Carmen Medina-Villar Silvia Andivia Enrique Bermúdez de Castro Francisco 《European Journal of Forest Research》2021,140(5):1081-1093
European Journal of Forest Research - Mediterranean riparian ecosystems provide key ecosystem services, such as climate regulation, water quality, and flood protection. Forest degradation and... 相似文献
79.
Esther Salazar Bruno Sansó Andrew O. Finley Dorit Hammerling Ingelin Steinsland Xia Wang Paul Delamater 《Journal of Agricultural, Biological & Environmental Statistics》2011,16(4):586-605
We consider the problem of forecasting future regional climate. Our method is based on blending different members of an ensemble
of regional climate model (RCM) simulations while accounting for the discrepancies between these simulations, under present
day conditions, and observational records for the recent past. To this end, we develop Bayesian space-time models that assess
the discrepancies between climate model simulations and observational records. Those discrepancies are then propagated into
the future to obtain blended forecasts of 21st century climate. The model allows for location-dependent spatial heterogeneities,
providing local comparisons between the different simulations. Additionally, we estimate the different modes of spatial variability,
and use the climate model-specific coefficients of the spatial factors for comparisons. We focus on regional climate model
simulations performed in the context of the North American Regional Climate Change Assessment Program (NARCCAP). We consider,
in particular, simulations from RegCM3 using three different forcings: NCEP, GFDL and CGCM3. We use simulations for two time
periods: current climate conditions, covering 1971 to 2000, and future climate conditions under the SRES A2 emissions scenario,
covering 2041 to 2070. We investigate yearly mean summer temperature for a domain in the South West of the United States.
The results indicated the RCM simulations underestimate the mean summer temperature increase for most of the domain compared
to our model. 相似文献
80.
Lacomba R Salcedo J Alegría A Barberá R Hueso P Matencio E Lagarda MJ 《Journal of agricultural and food chemistry》2011,59(10):5755-5762
The effects of simulated gastrointestinal digestion upon sialic acid and gangliosides in infant and follow-on formulas and human milk, as well as their bioaccessibility, have been evaluated. The gastric stage is the step that causes a greater decrease in sialic acid and ganglioside contents. The intestinal stage only decreases the total and individual contents of gangliosides. After gastrointestinal digestion, neither sialic acid nor gangliosides were found in the nonbioaccessible fraction. The highest bioaccessibility (100 × content in soluble fraction after gastrointestinal digestion/total content) of sialic acid is found in human milk (87%), followed by infant formula (77%) and follow-on formula (16%). In the case of gangliosides, the highest bioaccessibility is present in the follow-on formula (51%), followed by human milk (29%) and infant formula (5%). 相似文献