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991.
贺旭云 《湖南环境生物职业技术学院学报》2005,11(1):37-39
湖南省许多企业由于仍然受计划经济体制的阴影笼罩,缺乏竞争观念,品牌意识淡薄,导致品牌难上档次,知名品牌缺少.因此,必须整合湖南品牌战略、实施企业形象战略、培育品牌文化战略和实施品牌战略. 相似文献
992.
E.?PfeilerEmail author L.?A.?Hurtado L.?L.?Knowles J.?Torre-Cosío L.?Bourillón-Moreno J.?F.?Márquez-Farías G.?Montemayor-López 《Marine Biology》2005,146(3):559-569
The population genetics and historical demography of the swimming crab Callinectes bellicosus from the eastern Pacific were assessed using mitochondrial DNA (mtDNA) sequences from portions of the cytochrome c oxidase subunit I (COI) and cytochrome b (Cytb) genes. Analysis of molecular variance of sequence data from crabs collected from nine localities, ranging from the upper to lower Gulf of California and the outer coast of the Baja California peninsula, revealed an absence of population structure, suggesting a high level of gene flow over a wide geographic area. Maximum-likelihood estimates of long-term effective population size obtained with the program FLUCTUATE, in addition to highly significant values obtained from neutrality tests (Tajimas D, Fu and Lis D, and Fus FS) and mismatch analysis, are consistent with a population expansion dating to the Pleistocene epoch. Phylogenetic analysis of C. bellicosus sequences using both neighbor-joining and Bayesian methods revealed a widely distributed subclade (clade II) cryptically embedded at low frequency in the main (clade I) population. Although sequence divergence between the two clades was low (1.1% COI; 0.6% Cytb), statistical support for the split was high. The Kimura-2-parameter genetic distance between C. bellicosus and the sympatric and morphologically similar C. arcuatus was high (d=0.17) and similar to the genetic distance between C. bellicosus and the allopatric C. sapidus from the western Atlantic (d=0.18), suggesting an ancient (Miocene) divergence of C. bellicosus and C. arcuatus.Communicated by P.W. Sammarco, Chauvin 相似文献
993.
Differences in protein patterns of the soluble protein fraction among the sibling species Marenzelleria viridis (formerly type I) and M. neglecta (formerly type II) were investigated under common environmental conditions using two-dimensional gel electrophoresis (2D-PAGE). Protein expression was determined using general protein staining with Coomassie-blue and compared with radioactive labeling of proteins. In the well-resolved region of stained gels an average of 319 protein spots for M. viridis and 241 spots for M. neglecta could be detected. High sensitivity of radiolabeling allowed separation of an average of 517 and 496 spots for M. viridis and for M. neglecta, respectively. Differences in protein expression between both species could be attributed mainly to qualitative differences in protein patterns. Triplet pattern was used to calculate the genetic similarity of the two species. Thus, 373 protein spots were scored for this analysis; whereas 304 spots were invariant, 36 spots were specific for M. viridis, while 33 spots were specific for M. neglecta. The genetic similarity (F) of the two Marenzelleria sibling species was 0.815. Apart from presence and absence, differences between both species resulted either from slight changes in the isoelectric point or from molecular weight, but rarely from both. Genetic variability was found only among specimens of M. viridis. The experimental conditions to perform two-dimensional electrophoresis for these polychaete species were established for subsequent investigations on a proteomic level. Using 2D-PAGE we expect further insight into the evolutionary adaptation in Marenzelleria spp.Communicated by O. Kinne, Oldendorf/Luhe 相似文献
994.
During two expeditions of the R.V. Polarstern to the Arctic Ocean, pack ice and under-ice water samples were collected during two different seasons: late summer (September 2002) and late winter (March/April 2003). Physical and biological properties of the ice were investigated to explain seasonal differences in species composition, abundance and distribution patterns of sympagic meiofauna (in this case: heterotrophs >20 µm). In winter, the ice near the surface was characterized by extreme physical conditions (minimum ice temperature: –22°C, maximum brine salinity: 223, brine volume: 5%) and more moderate conditions in summer (minimum ice temperature: –5.6°C, maximum brine salinity: 94, most brine volumes: 5%). Conditions in the lowermost part of the ice did not differ to a high degree between summer and winter. Chlorophyll a concentrations (chl a) showed significant differences between summer and winter: during winter, concentrations were mostly <1.0 µg chl a l–1, while chl a concentrations of up to 67.4 µmol l–1 were measured during summer. The median of depth-integrated chl a concentration in summer was significantly higher than in winter. Integrated abundances of sympagic meiofauna were within the same range for both seasons and varied between 0.6 and 34.1×103 organisms m–2 in summer and between 3.7 and 24.8×103 organisms m–2 in winter. With regard to species composition, a comparison between the two seasons showed distinct differences: while copepods (42.7%) and rotifers (33.4%) were the most abundant sea-ice meiofaunal taxa during summer, copepod nauplii dominated the community, comprising 92.9% of the fauna, in winter. Low species abundances were found in the under-ice water, indicating that overwintering of the other sympagic organisms did not take place there, either. Therefore, their survival strategy over the polar winter remains unclear.Communicated by O. Kinne, Oldendorf/Luhe 相似文献
995.
Gastrotrichs are acoelomate micrometazoans common to marine interstitial environments of sublittoral sediments and exposed sandy beaches. The genus Neodasys (Chaetonotida) contains three marine species known from oceans and seas worldwide, and figures prominently in discussions of gastrotrich origins. To gain insight into the phylogenetic position of Neodasys and to understand the adaptive significance of muscle anatomy in marine interstitial gastrotrichs, a fluorescent phalloidin-linked marker was used to view the organization of muscles in two species from North America and Australia. Muscular topography of Neodasys cirritus from Florida, USA, and Neodasys cf. uchidai from Queensland, Australia, was found to be similar between species and to basal species of Macrodasyida; muscles were present in circular, longitudinal and helicoidal patterns. Musculature of the midgut region was partially reduced relative to basal macrodasyidan gastrotrichs, but well developed relative to most other chaetonotidan gastrotrichs. In general, muscle patterns in species of Neodasys closely correspond with those of other gastrotrichs of similar size and body type, and may therefore reflect a common adaptive solution to the physical demands of the interstitial environment. Results also suggest that reductions in midgut musculature may be functionally related to oviposition and, as such, are probably not homologous with similar reductions of circular muscles in other species of Chaetonotida.Communicated by O. Kinne, Oldendorf/Luhe 相似文献
996.
We performed field and laboratory studies to investigate how large adult Leptasterias polaris detect and locate their major prey, large infaunal bivalves, in the sediment bottom community. A field survey using SCUBA diving showed that 95% of the locations where L. polaris dug into the sediment bottom were over bivalves and this success rate was much greater than if digging was done at random (22%). Furthermore, when sea stars were provided with a low density of randomly distributed prey in a laboratory arena, they dug exclusively in locations where a clam had been buried. These observations indicated that L. polaris locates infaunal prey prior to investing energy into digging. Studies in a laboratory flow tank showed that L. polaris readily detected and moved towards its preferred prey Ensis directus whereas its responses to less preferred prey Mya truncata and Spisula polynyma were much weaker. The degree to which it oriented towards these three common prey seemed to reflect potential energy intake relative to foraging costs (which likely increase with the depth of the different prey) and risks from interactions with other carnivores (which are greatest when feeding on large prey). This is the first study to clearly demonstrate that sea stars use prey odours to locate infaunal prey.Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s00227-004-1497-1Communicated by R.J. Thompson, St. Johns 相似文献
997.
A.?J.?Pazos A.?Silva V.?Vázquez M.?L.?Pérez-Parallé J.?L.?Sánchez M.?AbadEmail author 《Marine Biology》2005,147(3):663-670
The sterol composition of three different populations of Ruditapes decussatus from three localities close to each other, but where different environment conditions prevail, was investigated over a period of 14 months. Sterols of adult clams were isolated by thin layer chromatography and identified by gas chromatography/mass spectrometry. In all samples, the major sterol component was cholesterol (>40% of total sterols); other sterols identified were 24-norcholesta-5,22-dienol, 22-cis-dehydrocholesterol, 22-trans-dehydrocholesterol, brassicasterol, 24-methylene-cholesterol, campesterol, stigmasterol, -sitosterol and isofucosterol. At each locality, changes in sterol levels followed specific and different patterns, which remained constant for the period studied and allowed the origin of the clams to be distinguished. Stepwise discriminant analysis, based on the percentage amounts of the sterols at each locality, indicated brassicasterol, 22-cis-dehydrocholesterol, cholesterol, 24-norcholestadienol and -sitosterol as discriminant variables that distinguish clam populations. Correct identification of the clam origin was achieved in 100% of the samples, demonstrating that sterols can justifiably be used as molecular biomarkers for determining the origin of this bivalve species.Communicated by O. Kinne, Oldendorf/Luhe 相似文献
998.
Scott?A.?ShafferEmail author Yann?Tremblay Jill?A.?Awkerman R.?William?Henry Steven?L.?H.?Teo David?J.?Anderson Donald?A.?Croll Barbara?A.?Block Daniel?P.?Costa 《Marine Biology》2005,147(4):833-843
Light-based archival tags are increasingly being used on free-ranging marine vertebrates to study their movements using geolocation estimates. These methods use algorithms that incorporate threshold light techniques to determine longitude and latitude. More recently, researchers have begun using sea surface temperature (SST) to determine latitude in temperate regions. The accuracy and application of these algorithms have not been validated on free-ranging birds. Errors in both geolocation methods were quantified by double-tagging Laysan (Phoebastria immutabilis Rothschild) and black-footed (P. nigripes Audubon) albatrosses with both leg-mounted archival tags that measured SST and ambient light, and satellite transmitters. Laysan albatrosses were captured and released from breeding colonies on Tern Island, northwestern Hawaiian Islands (23°52N, 166°17W) and Guadalupe Island, Mexico (28°31N, 118°10W) and black-footed albatrosses from Tern Island. Studies were carried out between December 2002 and March 2003. For all birds combined, the mean ± SD great circle (GC) distance between light-based locations and satellite-derived locations was 400±298 km (n=131). Errors in geolocation positions were reduced to 202±171 km (n=154) when light-based longitude and SST-based latitude (i.e. SST/light) were used to establish locations. The SST/light method produced comparable results for two Laysan albatross populations that traveled within distinctly different oceanic regions (open ocean vs more coastal) whereas light-based methods produced greater errors in the coastal population. Archival tags deployed on black-footed albatrosses returned a significantly higher proportion of lower-quality locations, which was attributed to interference of the light sensor on the tag. Overall, the results demonstrate that combining measures of light-based longitude and SST-based latitude significantly reduces the error in location estimates for albatrosses and can provide valid latitude estimates during the equinoxes, when light-based latitude measurements are indeterminate.Communicated by J.P. Grassle, New Brunswick 相似文献
999.
Marc?Le Lann Catherine?ElleouetEmail author Fran?ois?Quentel Christian?Louis?Madec 《Environmental Chemistry Letters》2003,1(1):98-102
Cathodic adsorptive stripping voltammetry is one of the most sensitive analytical methods for ultratrace analysis. The detection
limit is usually lower than 10−9 mol/L. Most adsorptive stripping procedures have been focused on the one ligand/one analyte approach. In order to reduce
analysis time and sample volume, the possibility of simultaneously determining several metals by cathodic stripping voltammetry
using a mixture of ligands was explored, e.g., by Colombo and van den Berg (1997). Here, we describe a new procedure for quantifying
chromium and copper using 2,2′-bipyridine and 8-hydroxyquinoline (oxine). The effect of various operational parameters such
as buffer type, ligand concentration, potential and time collection were assessed and optimized. Possible interferences by
trace metals and organic matter were also investigated. Applicability for fresh water is illustrated.
Electronic Publication 相似文献
1000.