984 resultados para Transports et communications


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Zhikong scallop (Chlamys farreri Jones et Preston 1904) is one of the most important aquaculture species in China. The development of a genetic linkage map would provide a powerful tool for the genetic improvement of this species. Amplified fragment length polymorphism (AFLP) is a PCR-based technique that has proven to be powerful in genome fingerprinting and mapping, and population analysis. Genetic maps of C. farreri were constructed using AFLP markers and a full-sib family with 60 progeny. A total of 503 segregating AFLP markers were obtained, with 472 following the Mendelian segregation ratio of 1:1 and 31 markers showing significant (P< 0.05) segregation distortion. The male map contained 166 informative AFLP markers in 23 linkage groups covering 2468 cM. The average distance between markers was 14.9 cM. The female genetic map consisted of 198 markers in 25 linkage groups spanning 3130 cM with an average inter-marker spacing of 15.8 cM. DNA polymorphisms that segregated in a 3:1 ratio as well as the AFLP markers that were heterozygous in both parents were included to construct combined linkage genetic map. Five shared linkage groups, ranging from 61.1 to 162.5 cM, were identified between the male and female maps, covering 431 cM. Amplified fragment length polymorphism markers appeared to be evenly distributed within the linkage groups. Although preliminary, these maps provide a starting point for the mapping of the functional genes and quantitative trait loci in C. farreri.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Zhikong scallop (Chlamys farreri) is an economically important aquaculture species in China; however, frequent mass mortality seriously affects the development of its industry. Genetic linkage map is useful for genetic improvement and selective breeding of C. farreri. Linkage maps were constructed using an intraspecific F-1 cross and amplified fragment length polymorphism (AFLP) markers. Thirty-two selected AFLP primer combinations produced 545 AFLP markers that were polymorphic in either of the parents and segregated in the progeny. Of these segregating markers, 166 were mapped to 19 linkage groups of the female framework map, covering a total of 1503.9 cM, with an average marker spacing of 10.2 cM; and 197 markers were assigned to 20 linkage groups of the male map, covering a total of 1630.7 cM, with 9.2 cM per marker. A sex-linked marker was mapped on the female map with zero recombination and a LOD of 27.3. The genetic length of C farreri genome was estimated as 1889.0 cM for the female and 1995.9 cM for the male. The coverage of the framework map was calculated as 79.6% for the female and 81.7% for the male. When the triplets and doublets were considered, the observed length of the map was calculated as 1610.2 cM with coverage of 85.2% for the female, and 1880.5 cM with coverage of 94.2% for the male. The genetic maps presented here will serve as a basis for the construction of a high-resolution genetic map and mapping of economically important genes. (C) 2004 Published by Elsevier B.V.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Triploid scallops are valuable for aquaculture because of their enlarged adductor muscle, and tetraploids are important for the commercial production of triploids. We tested tetraploid induction in the zhikong scallop by inhibiting polar body I in newly fertilized eggs. The ploidy of resultant embryos was determined by chromosome counting at 2- to 4-cell stage and by flow cytometry thereafter. Embryos from the control groups were mostly diploids (79%), along with some aneuploids. Embryos from the treated groups were 13% diploids, 18% triploids, 26% tetraploids, 13% pentaploids, and 36% aneuploids. Tetraploids, pentaploids, and most aneuploids suffered heavy mortality during the first week and became undetectable among the larvae at day 14. Five tetraploids (2%) were found among a sample of 267 spat from one of the replicates, and none was detected at day 450. The adductor muscle of triploid scallops was 44% heavier (P < .01) than that of diploids, confirming the value of the triploid technology in this species.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Large-insert bacterial artificial chromosome (BAC) libraries are necessary for advanced genetics and genomics research. To facilitate gene cloning and characterization, genome analysis, and physical mapping of scallop, two BAC libraries were constructed from nuclear DNA of Zhikong scallop, Chlamys farreri Jones et Preston. The libraries were constructed in the BamHI and MboI sites of the vector pECBAC1, respectively. The BamHI library consists of 73,728 clones, and approximately 99% of the clones contain scallop nuclear DNA inserts with an average size of 110 kb, covering 8.0x haploid genome equivalents. Similarly, the MboI library consists of 7680 clones, with an average insert of 145 kb and no insert-empty clones, thus providing a genome coverage of 1.1x. The combined libraries collectively contain a total of 81,408 BAC clones arrayed in 212 384-well microtiter plates, representing 9.1x haploid genome equivalents and having a probability of greater than 99% of discovering at least one positive clone with a single-copy sequence. High-density clone filters prepared from a subset of the two libraries were screened with nine pairs of Overgos designed from the cDNA or DNA sequences of six genes involved in the innate immune system of mollusks. Positive clones were identified for every gene, with an average of 5.3 BAC clones per gene probe. These results suggest that the two scallop BAC libraries provide useful tools for gene cloning, genome physical mapping, and large-scale sequencing in the species.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A quasi-global high-resolution HYbrid Coordinate Ocean Model (HYCOM) is used to investigate seasonal variations of water transports through the four main straits in the South China Sea. The results show that the annual transports through the four straits Luzon Strait, Taiwan Strait, Sunda Shelf and Mindoro Strait are -4.5, 2.3, 0.5 and 1.7 Sv (1 Sv=10(6) m(3)s(-1)), respectively. The Mindoro Strait has an important outflow that accounts for over one third of the total inflow through the Luzon Strait. Furthermore, it indicates that there are strong seasonal variations of water transport in the four straits. The water transport through the Luzon Strait (Taiwan Strait, Sunda Shelf, Mindoro Strait) has a maximum value of -7.6 Sv in December (3.1 Sv in July, 2.1S v in January, 4.5Sv in November), a minimum value of -2.1 Sv in June (1.5 Sv in October, -1.0 Sv in June, -0.2 Sv in May), respectively.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

We examined the growth, survival and immune response of the scallop, Chlamys farreri, during a 1-year period in deep water of Haizhou Bay. Scallops were cultured using two methods: (1) in lantern nets at a 5 m depth and (2) in a bottom culture system (sleeves) on the seabed at about a 25 m depth. Shell heights, meat dry weight and immune activities in the haemolymph (superoxide dismutase and myeloperoxidase) were measured bimonthly or quarterly from July 2007 to June 2008. Survival was measured at the end of the study and environmental parameters in the experimental layers were monitored during the experiment. The growth and immune activities of scallops were lower when the water temperature was high, which was consistent with the main mortality occurring in summer. The growth and immunity of scallops were higher in the suspended culture than in the bottom culture during the experiment, with the exception of shell growth during the last study period. Survival of scallops in the suspended culture (54.6 +/- 12.3%) was significantly lower than that in the bottom culture (86.8 +/- 3.5%) at the end of this study. We conclude from our results that the high mortality of C. farreri can be prevented by culturing them in a bottom culture system before November of the first year, and then transferring them to a suspended culture to improve scallop production.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Mass mortalities of cultured zhikong scallops (Chlamys farreri) have occurred each summer in most culture areas of northern China since 1996. Among the hypothesized causes are high culture density, infectious disease and genetic inbreeding. To investigate these potential agents, C. farreri were deployed at three densities (low, medium and high) at three sites (Jiaonan, Penglai and Yantai) in the summer of 2000. Scallops were sampled for survival, growth and histopathology before, during and after a mortality episode. Most of the mortality occurred in July and August, during and toward the later part of the spawning season, when water temperature reached 23-26 degrees C. Final cumulative mortalities reached 85% to 90% at all three sites. Scallops in the medium and high densities had higher initial death rates than did those at the low density. High densities also inhibited growth. Ciliates from the genus Trichodina, larvae of various organisms and anomalous secretions were observed in sections of the gill cavity, with highest prevalence during and at the end of the mortality period. Prokaryotic inclusion bodies were found in the soft tissues, but their prevalence was low and apparently without correlation with mortalities. Genetic analysis with random amplified polymorphic DNA markers showed slightly lower heterozygosity in the cultured stocks (0.301) than in the wild stocks (0.331). It is possible that the mortalities are caused by a combination of several factors such as stress associated with reproduction, high temperature, overcrowding and poor circulation in the growout cages, opportunistic invaders or pathogens, and possibly inbreeding. (c) 2005 Elsevier B.V. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The impact of starvation on larvae of Ivory shell Babylonia formosae habei was studied in a laboratory experiment. Newly hatched veligers showed considerable tolerance to starvation due to their endogenous yolk material, and time to the point-of-no-return (PNR; the threshold point during starvation after which larvae can longer metamorphose even if food is provided) was calculated to be 104.5 h. However, starvation still affected larval growth, survival, and metamorphosis. Mean shell length of larvae increased 49.77 mum day(-1) for nonstarved, but only 11.13 mum day (-1) for larvae starved for 108 h. After larvae began feeding, their growth rates rapidly recovered to the level of the nonstarved following short periods of starvation (less than 48 h), but were inhibited and unable to ever reach the level of the nonstarved when being starved beyond 48 h. Percent metamorphosis was 53.75% for the nonstarved, but all larvae died before 10 days for those starved for 108 h. Starvation not only affected larval time to reach metamorphosis, but also caused the delay in the time to metamorphosis. For the nonstarved, larvae took only 11.5 days to reach spontaneous metamorphosis, but they took 20 days to reach spontaneous metamorphosis when starved for 96 h, and this duration of delayed metamorphosis reached 8.5 days. Furthermore, the importance of yolk material for maintaining larval survival of B. formosae habei during starvation periods is also discussed. (C) 2004 Elsevier B.V. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Jackson, Peter, 'Strat?gie et id?ologie: le haut commandement fran?ais et la guerre civile espagnole ', Guerres Mondiales et Conflits Contemporains - Revue Trimestrielle d'Histoire (2001) 199 pp.111-133 RAE2008

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Trotter, David, 'Les manuscrits latins de la Chirurgia d'Albucasis et la lexicographie du latin m?di?val', Archivum Latinitatis Medii Aevi (Bulletin Du Cange) (2001) 59(1) pp.181-202 RAE2008

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Rozprawa jest próbą wypracowania kompromisu pomiędzy skrajnie morfologicznymi i uniwersalistycznymi podejściami do problematyki aspektu. Jej głównym celem jest wykazanie, jakimi środkami językowymi wyrażane są w języku duńskim i polskim perfektywność i imperfektywność. Za punkt wyjścia przyjęto ujęcie aspektu jako kategorii semantycznej, której wykładniki mogą mieć zróżnicowany charakter. Jednocześnie założono, że aspekt wyrażany jest w kontekście szerszym niż sama forma czasownika, a ostateczna wartość aspektu na poziomie zdania jest ściśle związana z rodzajem czynności (Aktionsart), do którego sytuacja opisywana w danym zdaniu należy. Zdefiniowano pojęcie konstelacji werbalnej (za Smith 1997), która składa się z podmiotu, orzeczenia oraz ewentualnie dopełnienia lub okolicznika miejsca/kierunku i stanowi minimalny kontekst, w którym rodzaje czynności mogą być wyrażane. W zaproponowanej teorii aspektu przewidziano dwie nadrzędne wartości semantyczne -perfektywność i imperfektywność, w ramach których ze względu na brak inwariantu semantycznego wyróżniono odpowiednio trzy typy znaczeń perfektywnych (terminatywne, inchoatywne i semelfaktywne) oraz dwa typy znaczeń imperfektywnych (kursywne i habitualno-generyczne). W celu ustalenia wspólnych mianowników semantycznych dla obu nadrzędnych grup na nowo zdefiniowano reichenbachowski czas zdarzenia, czas mówienia oraz czas odniesienia. Otrzymane definicje łączą perfektywność z punktowym a imperfektywność - z linearnym czasem odniesienia. Obszar badań ograniczono do środków wyrazu perfektywności i imperfektywności w duńskich i polskich prostych zdaniach oznajmujących bez negacji, odnoszących się do przeszłości. Ponadto pominięto zjawiska związane z tzw. dokonanością i niedokonanością sekundarną, w tym między innymi czasowniki wieloprefiksowe. Mimo pewnych podobieństw w wyrażaniu perfektywności i imperfektywności w obu badanych językach, różnice w charakterze wykładników znaczeń aspektualnych języka duńskiego i polskiego są znaczne. W związku z brakiem możliwości wyrażania znaczeń aspektualnych za pomocą odpowiednich afiksów w języku duńskim zachodzi duże ryzyko błędnej interpretacji wartości aspektualnej zdania. Istnieje jednak szereg konstrukcji syntaktycznych umożliwiających jednoznaczne oznaczenie perfektywności lub imperfektywności. W języku polskim znaczenia aspektualne mogą być wyrażane przede wszystkim za pomocą wykładników morfologicznych, lecz również za pomocą konstrukcji składniowych.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This article describes Yasmina Khadra’s autobiographical work composed of two books: "L’écrivain" and "L’imposture des mots" and its reception in France. The main purpose of this study was to establish the literary genre of these books, which implies determining whether Khandra’s work represents an autobiography or an autofiction with reference to P. Lejeune’s and V. Colonna’s theoretical studies. The dividing line between two genres in Khandra’s works refl ects his inner split between being either a solder or a writer. The presentation will also help to understand the controversy resulting from Khandra’s participation in Algerian civil war. Moreover the analysis is related to modern Algerian history.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The aim of the paper is to present the specificity of oral argumentative competence in a foreign language and to propose a tentative model of task-based learning of argumentative discourse. It is assumed in the paper that the communicative situation tasks proposed during classes of French as a foreign language in the French Philology Department should contribute to the academic discourse learning. In the paper we present an analysis of two fragments of argumentative situations; the first one concerns the so-called everyday argumentative situation and another one illustrates an argumentative orientation of academic discourse.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

On the basis of two indecidable texts (Thomas Clerc, “Paris, musée du XXIe siècle. Le dixième arrondissement”, Gallimard 2007 and Philippe Vasset, “Un livre blanc”, Fayard 2007), we will reflect on new approaches to the city in contemporary French litterature. Clerc and Vasset, in their respective texts, suggest considering litterature as a series of practices connected with the exploration of the city (Clerc) and of the urban area (Vasset) according to the idea of an arbitrary itinerary. The image of the city whose space, subject to a permanent process of museifi cation, is constantly considered to be a work of art (Clerc) contrasts with a project of viewing the deserted areas of the city and of its surroundings as an infinite collection of “artistic installations” created in daily life (Vasset). Clerc’s and Vasset’s artistic mentality leads them to the fascination with “works of involuntary art”, both concrete signs and tangible proof of the transitional period which they try to describe systematically, following, at the same time, the principles of an axonometric city map.