• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 525
  • 70
  • 12
  • 11
  • 11
  • 10
  • 7
  • 7
  • 7
  • 7
  • 7
  • 5
  • 4
  • 4
  • 2
  • Tagged with
  • 768
  • 405
  • 156
  • 153
  • 135
  • 119
  • 109
  • 82
  • 73
  • 72
  • 72
  • 69
  • 62
  • 59
  • 54
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

'n Vergelykende ondersoek van die morfologie en ultrastruktuur van die maag en maagwand van die algvoeder Oreochromis mossambicus (Peters) en die roofvis Hydrocynus forskahlii Cuvier

19 November 2014 (has links)
D.Sc. / Please refer to full text to view abstract
32

Bacillus cereus e Bacillus subtilis na suplementação dietária de juvenis de Tilápias-do-Nilo (Oreochromis niloticus) e seu efeito probiótico

Mello, Hurzana de [UNESP] 23 March 2012 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:22:22Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-03-23Bitstream added on 2014-06-13T18:48:57Z : No. of bitstreams: 1 mello_h_me_jabo.pdf: 2134620 bytes, checksum: cc55d8c2f3908cdaac223e6c20938cea (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Universidade Estadual Paulista (UNESP) / Os objetivos deste trabalho foram os de avaliar o percentual de sobrevivência, a microbiota instestinal, a integridade da mucosa, e a qualidade da carcaça de juvenis de Tilápias-do-Nilo, Oreochromis niloticus, após 80 dias de alimentação com dieta contendo aditvo probiótico (Bacillus cereus 4,0 x 108 UFC g-1 e Bacillus subtilis 4,0 x 108 UFC g-1), na proporção de 4g/kg de ração peletizada. O delineamento experimental foi inteiramente casualizado com dois tratamentos, sendo um grupo controle e outro alimentado com dieta tratado. Os resultados foram analisados estatisticamente pela análise de variância (ANOVA) e, quando significativos, pelo teste de Tukey (P<0,05). Os resultados demonstraram que as tilápias do grupo tratado apresentaram percentual de sobrevivência relativa maior (P<0,05) que o do grupo controle e colonização intestinal por B. cereus e B. subtillis com maior (P<0,05) número de unidades formadoras de colônia em relação ao grupo controle e a integridade da mucosa intestinal avaliada por histomorfometria apresentou valores maiores (P<0,05) que o observado no grupo controle. Neste caso, o grupo alimentado com aditivo probiótico apresentou vilosidades mais altas e mais largas, além de maior número de células caliciformes que o observado no grupo controle. Em relação à qualidade de carcaça os resultados demonstraram que houve interferência positiva (P<0,05) do probiótico no grupo tratado em relação ao controle quanto aos teores de proteína e extrato etéreo. Estes resultados permitem inferir que a suplementação com probiótico, como testado neste estudo, induziu a colonização intestinal por bactérias benéficas, promoveu maior percentual de sobrevivência relativa, diminuiu a descamação da mucosa e favoreceu o aumento do número de células caliciformes / Our objectives were to assess the percentage of survival, mucosal integrity, intestinal microbiota and carcass quality of juvenile tilapia, the Nile, Oreochromis niloticus, after 90 days of feeding a diet supplemented with probiotic (Bacillus cereus 4.0 x 108 CFU g-1 and Bacillus subtilis 4.0 x 108 CFU g-1), the proportion of 4g/kg pelleted feed. The experimental design was completely randomized with two treatments, one with a control group and another fed diet supplemented. The results were analyzed statistically by the Tukey test (P<0.05). The experimental design was completely randomized with two treatments, one with a control group and another fed diet supplemented. The results were analyzed statistically by the Tukey test (P<0.05). The results showed that tilapia fed with the supplemented diets obtained the higher survival rates (P<0.05) than the control group and higher integrity (P<0.05) of the intestinal mucosa assessed by histomorphometry. This case, the group fed a diet supplemented presented taller and wider villi, epithelial cells with thicker villous and a increased number of goblet cells than observed in the control group. In relation to carcass quality the results demonstrated that in the treated group there was interference (P<0.05) of the probiotic compared to control group for the levels of protein and acid hidrolyzed fat. The fish fed the diet with probiotics showed intestinal colonization by B. cereus and B. subtilis (P>0.05) and higher number (P<0.05) of colony forming units compared to the control group. These results allow us to conclude that supplementation with probiotics, as tested in this study, can induce the intestinal colonization by beneficial bacteria that decrease the mucosal desquamation and favored the increase in the number of goblet cells
33

Promoter activity of cold-induced protein of Tilapia, Oreochromis mossambicus

Lin, Hou-chi 02 September 2008 (has links)
Temperature affects the sexual differentiation and the development of brain of tilapia, Oreochromis mossambicus. Expressed sequence tags ( EST ) derived from the developing tilapia brain had been cloned in our laboratory. In the present study, we focus on the promoter of cold-induced protein. The promoter sequence of cold-induced protein from the transcription start site ( TSS ) were cloned by 5¡¦ rapid amplification of cDNA end ( 5¡¦-RACE ) and Genome Walker DNA Walking. The bioinformatic analysis was performed on the fragment for predicting the transcription factor binding site. We used the digestion method of restriction enzymes and an electrophoresis mobility shift assay to find transcription factor binding site. The results indicated that there is a putative POU3F2 binding site in the fragment form -157 bp to -149 bp. The luciferase activity assay was performed on this site and results indicated that wild type showed the enhanced promoter activity. However, site-direct mutagenesis of this site did not result in the reduction of the promoter activity.
34

The effect of population density on the rate of growth of the cichlid fish, Tilapia mossambica : an experimental tank study

Schneider, Laurence H. January 1978 (has links)
No description available.
35

Studies on aromatase inhibition and gene transfer in Oreochromis niloticus, and their effects on sexual differentiation

Haghpanah, Vahid January 1997 (has links)
No description available.
36

Cytochrome P450 aromatase (CYP19) and sex differentiation in the Nile tilapia Oreochromis niloticus

Kwon, Joon Yeong January 2000 (has links)
Sex steroids are generally considered as natural sex inducers in fish. Aromatase (cytochrome P450 aromatase) catalyses androgens into oestrogens in the steroidogenic pathway. Three different approaches were taken to elucidate the action of aromatase in relation to sex differentiation in the Nile tilapia Oreochromis niloticus. The first was treatment with Fadrozole TM,a non-steroidal aromatase inhibitor (Al), by incorporating it in the diet or by immersing fish in a solution containing Al during the sex differentiation period. The Al treatment masculinised genetic females, indicating the importance of aromatase in sex differentiation. The result revealed that the most sensitive time to Al lies between 11-18 dpf (days post fertilisation). A partial brain type aromatase cDNA (1707bp) was identified from a brain cDNA library of O. niloticus. The amino acid sequence (that corresponds to exon 2-9) derived from this showed 63.7% identity to a previously reported ovarian aromatase gene of this species, and 96.7% identity to the brain type aromatase gene of a closely related species O. mossambicus. A semi-quantitative RT-PCR method was established to investigate expression of brain and ovarian aromatase genes during ontogeny. No sexually dimorphic expression of brain aromatase mRNA was detected. However, expression of ovarian aromatase was down-regulated from 15 to 23 dpf in genetic males but upregulated in genetic females. This period overlaps closely with the most sensitive period to Al. The pattern of temperature-dependent sex determination (TSD) was examined using three different genotypes (XX, XY, YY) at two temperatures (28 and 36°C). The results showed a bidirectional pattern of TSD. YY groups showed a significant percentage of feminisation at the higher temperature, which was suppressed by the Al treatment, implying that aromatisation is mechanistically associated with TSD in this species.All of these data consistently suggest that aromatase plays a crucial role in sex differentiation, and that the decisive aromatisation takes place between 13-25 dpf in this species. Considering the timing (26-30 dpf) of the first appearance of steroid producing cells in the gonadal area, the decisive aromatisation is not likely to take place there. The brain could be the primary aromatisation site in fish sex differentiation.
37

The embryological development of the Tilaiine fishes /

Katz, Michelle. January 1988 (has links)
Thesis (MFA)--Rochester Institute of Technology, 1988. / Includes bibliographical references.
38

Tilapia fingerling production in Honduras

Triminio de Meyer, Suyapa, January 2005 (has links) (PDF)
Thesis(M.S.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references.
39

Probióticos na alimentação de tilápias do Nilo: desempenho produtivo, hematologia e imunologia

Iwashita, Marina Keiko Pieroni [UNESP] 21 June 2012 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:30:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-06-21Bitstream added on 2014-06-13T20:21:09Z : No. of bitstreams: 1 iwashita_mkp_dr_jabo.pdf: 379506 bytes, checksum: 3797c036c478da41503dc65428490a49 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Universidade Estadual Paulista (UNESP) / A atividade do probiótico contendo Saccharomyces cerevisiae, Bacillus subtilis e Aspergillus oryzae foi avaliada através da inclusão de níveis do produto na dieta de tilápia do Nilo (Oreochromis niloticus). Foi avaliado seu efeito no desempenho produtivo, na resposta inflamatória e na resposta imune dos peixes, através do efeito protetor contra desafios infecciosos de Aeromonas hydrophila e Streptococcus iniae. Três dietas foram formuladas: uma sem a adição do probiótico (Controle); T1, suplementada com 5g; e T2 suplementada com 10g de probiótico por quilo de ração. As dietas continham os níveis de proteína indicados para a fase de alevinagem. Após 1, 3, 7 e 14 dias do início da alimentação coletas foram realizadas, e foi averiguado a colonização do trato gastrointestinal. Foram recuperados do trato 1,08x106 e 3,81x107 UFC.g-1 de B. subtilis e 1,0x105 e 1,06x106 de S. cerevisiae, dos tratamentos suplementados com 5 e 10g de probiótico respectivamente. Não foi possível recuperar o A. oryzae. Resultados de desempenho produtivo mostraram valores superiores em 30 dias de alimentação com 10g de probiótico por kg de ração. O hemograma e leucograma dos peixes que receberam o probiótico mostraram alterações e melhor resposta inflamatória. Estes peixes mostraram valores de cortisol e glicemia plasmática reduzidos. Os dados hematológicos dos peixes submetidos ao desafio bacteriano mostraram que o probiótico proporcionou maior resistência dos eritrocitócitos às diferenças osmóticas e à produção de ânion superóxido. Doses de 5 e 10g de probiótico por kg de ração garantiu maiores taxas de sobrevivência contra A. hydrophila, e doses de 10g de probiótico por kg de ração, maior sobrevivência à infecção S. iniae / The probiotic activity of Saccharomyces cerevisiae, Bacillus subtilis and Aspergillus oryzae was evaluated by including product levels in the diet of Nile tilapia (Oreochromis niloticus). Performance, inflammatory and immune response, and protective effect against challenge infection with Aeromonas hydrophila and Streptococcus iniae was evaluated. Three diets were formulated: without probiotic (Control), T1, supplemented with 5g and T2, supplemented with 10g probiotic per kg of diet. The diets contained protein levels indicated for nursery phase. After 1, 3, 7 and 14 days after the beginning of feeding, samples were taken, gastrointestinal tract colonization was observed. 1.08 x 106 and 3.81 X107 CFU.g-1 of B. subtilis and 1.0 x 105 and 1.06 x 106 of S. cerevisiae, were recovered from the tract from fish fed 5 and 10g of probiotic respectively. It was unable to recover A. oryzae. Performance data showed higher values, in 30 days of probiotic feeding with 10g per kg of feed. The CBC and WBC of fish that received the probiotic showed better changes and inflammatory response. These fish showed levels of cortisol and reduced plasma glucose. The blood of the fish subjected to bacterial challenge showed that the probiotic provided eritrocitócitos greater resistance to the osmotic differences and the production of superoxide anion. Doses of 5 and 10g of probiotic per kg of ration ensured the highest survival rates against A. hydrophila, and doses of 10 g probiotic per kg of diet increased survival against S. iniae infection
40

Suplementação de zinco em dietas: desempenho produtivo e resposta hemática e imunológica da tilápia-do-nilo submetida a desafio bacteriano

Teixeira, Caroline Pelegrina [UNESP] 30 July 2013 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:32:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-07-30Bitstream added on 2014-06-13T20:04:45Z : No. of bitstreams: 1 teixeira_cp_dr_botfmvz.pdf: 507042 bytes, checksum: 2edf6e19fc47b29717af3db6a2060e54 (MD5) / O presente trabalho compõe-se de dois estudos. No primeiro, avaliou-se os efeitos da suplementação de zinco (0, 20, 40, 80, 160 e 320 mg kg-1) na absorção de zinco (Zn), cobre, ferro e manganês de 60 peixes. No segundo estudo, foram avaliados os efeitos do zinco nos parâmetros produtivos de tilápias-do-Nilo. Foram utilizados 288 peixes, com peso de 7,67 ± 0,23 g, distribuídos ao acaso em 36 aquários de 250 L e alimentados com dietas práticas contendo níveis crescentes de zinco suplementar. A fonte de zinco utilizada foi o sulfato de zinco monoidratado. Ao final de 130 dias experimentais, foram avaliados ganho de peso, consumo de ração, conversão alimentar, taxa de retenção proteica, sobrevivência, atividade da fosfatase alcalina, retenção de zinco nos ossos e carcaça. A suplementação de Zn não influenciou a absorção de ferro. O excesso de zinco suplementar prejudicou a absorção de cobre pelo epitélio intestinal dos peixes. A absorção de manganês foi prejudicada quando os animais foram alimentados com dietas suplementadas com 320 mg Zn kg-1. A concentração de zinco na carcaça e atividade da fosfatase alcalina responderam positivamente ao aumento de nível de suplementação dietética de zinco. As análises de regressão segmentada demonstraram que maior ganho de peso, retenção proteica e melhor conversão alimentar dos peixes foram estimados em 59,84; 80,00 e 82,62 mg Zn kg-1 da dieta, respectivamente. Com base na retenção óssea de zinco, a exigência deste mineral em dietas práticas para juvenis de tilápia-do-Nilo é de 82,71mg kg-1 / This study was divided in two trials. First: the trial evaluated the effects of zinc supplementation (0, 20, 40, 80, 160, 320 mg kg-1 diet) on zinc (Zn), copper (Cu), iron (Fe) and manganese (Mn) availability. Second: a 130-day feeding trial was undertaken to evaluate the effect of zinc on growth performance of Nile tilapia juveniles (Oreochromis nilocticus). 288 Nile tilapia fingerlings with 7.67 ± 0.23 g weight (mean±SD) were randomly stocked into 36 250 L-aquaria and fed practical diets containing graded levels of zinc. Zinc source was zinc sulfate monohydrate (ZnSO4.H2O). Excess of zinc supplement has damaged the absorption of copper by intestinal epithelium. The absorption of manganese was injured when the animals were fed diets supplemented with 320 mg Zn kg-1. Concentration of zinc in carcase and alkaline phosphatase activity increased with the increasing zinc levels. At the end of the experimental period fish were weighed to evaluate weight gain, feed intake, feed conversion ratio, protein retention, survival, alkaline phosphatase activity and zinc tissues saturation. The broken-line analysis showed that the greater weight gain, protein retention and better feed of fish were estimated at 59.84, 80.00 and 82.62 mg Zn kg-1, respectively. Based on bone absorption of zinc, the requirement of this mineral in practical diets for juvenile of Nile tilapia is 82.71 mg kg-1

Page generated in 0.0246 seconds