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Criopreservação de sêmen de tambaqui Colossoma macropomum em criotubo
Get PDFThe semen cryopreservation in cryotubes reduces the time needed for filling, freezing and thawing of the samples, while optimizing the procedures for artificial fertilization. However, no study has yet been performed with tambaqui semen in this container. The aim of this study was to evaluate the influence of cryotubes (1.6 and 4.5 mL) and thawing time (60ºC/70s and 60ºC/90 s) on the quality and fertility of tambaqui cryopreserved semen. For that, semen samples were diluted in freezing solution (1:9) composed with 75% glucose 290 mOsm , 10% methylglycol and 5% egg yolk, and frozen in liquid nitrogen vapor (in a dry shipper), and stored in liquid nitrogen (-196 °C). The semen samples was thawed at 60ºC in bath water during 70s or 90s and the semen quality was evaluated (Total motility - MT; Progressive motility - MP; Curvilinear velocity - VCL; Straight-line velocity - VSL and Average path velocity - VAP). In this study was also determined the time viability of spermatozoa thawed, maintained under refrigeration at 5°C, and assessed over 24 hours. Besides the kinetic parameters were evaluated sperm morphology and membrane integrity of spermatozoa. The fertilizing capacity of semen was evaluated from the samples thawed in the best time. All parameters of sperm kinetic showed higher values when the semen samples were thawed in 90 s compared to 70 s, independently of cryotube type. No significant differences were observed in sperm kinetic parameters after thawing between samples frozen in 1.6 ml and 4.5 mL cryotubes, except for total motility that was higher in 1.6 mL (47 ± 14% ) compared with 4.5 mL cryotubes (40 ± 11%), independently of thawing time. After activation, the spermatozoa significantly reduced the values of kinetic parameters within 37 seconds, except the MT which remained constant during this period. Relying on the sperm parameters evaluated (VCL, VSL, VAP and membrane integrity for both cryotubes and MT, MP and morphology only for 1.6 mL cryotube) the frozen semen maintained the quality during 3h after thawing. The fertilization rate obtained with fresh semen (74±6%) was higher than cryopreserved semen (1.6 mL - 45±9% and 4.5 mL - 41±12%). The two cryotubes did not differ in this parameter. A high correlation (p <0.05) was observed between fertility and sperm kinetics parameters (MT - 89%, MP - 86%; VCL - 79%; VSL - APV and 69% - 78%). It is concluded that 1.6 and 4.5 mL cryotubes can be used in the cryopreservation of tambaqui semen being recommended to be thawed at 60°C for 90s and their use in fertilization procedures within 3 hours after thawing since kept at 5°C.A criopreservação de sêmen em criotubos reduz o tempo necessário para o envase, congelamento e descongelamento das amostras, além de otimizar os procedimentos de fertilização artificial. No entanto, nenhum estudo ainda foi realizado com o sêmen de tambaqui neste recipiente. Assim, o objetivo do presente trabalho foi avaliar a influência do tipo de criotubo (1,6 e 4,5 mL) e do tempo de descongelamento (60ºC/70s e 60ºC/90s) sobre a qualidade e fertilidade do sêmen de tambaqui criopreservado. Para isso, amostras de sêmen foram diluídas em solução de congelamento (1:9 v/v) composta por 75% de glicose 290 mOsm, 10% de metilglicol e 5% de gema de ovo, sendo envasadas em criotubos de 1,6 e 4,5 mL, congeladas em vapor de nitrogênio líquido no botijão dry-shipper (-175ºC) e armazenadas em botijão criogênico a -196°C. Para avaliação do tempo de descongelamento do sêmen, os criotubos foram imersas em água a 60°C durante 70 s ou 90 s e a qualidade espermática imediatamente avaliada (Motilidade total - MT; Motilidade progressiva - MP; Velocidade curvilinear - VCL; Velocidade em linha reta - VSL e Velocidade média da trajetória - VAP). Neste estudo foi determinado também o tempo de viabilidade dos espermatozoides descongelados, mantidos sob refrigeração a 5°C e avaliados durante 24 horas. Além dos parâmetros de cinética espermática foram avaliadas a morfologia e a integridade da membrana plasmática dos espermatozoides. A capacidade de fertilização do sêmen foi avaliada a partir das amostras descongeladas no melhor tempo. Todos os parâmetros de cinética espermática apresentaram valores superiores quando as amostras de sêmen foram descongeladas por 90s em relação ao tempo de 70s, independentemente do tipo de criotubo. Não foram observadas diferenças significativas nos parâmetros de cinética espermática pós-descongelamento entre as amostras congeladas nos criotubos de 1,6 e 4,5 mL, com exceção da MT que foi superior nos criotubos de 1,6 mL (47±14%) em comparação com os criotubos de 4,5 mL (40±11%), independentemente do tempo de descongelamento. Após ativação, os espermatozoides reduziram significativamente os valores dos parâmetros de cinética dentro de 37 segundos, exceto a MT que se manteve constante neste período. Baseando-se na maior parte dos parâmetros espermáticos avaliados (VCL, VSL, VAP e Integridade da membrana plásmatica para ambos os criotubos e MT, MP e Morfologia espermática somente para o criotubo de 1,6 mL) o sêmen congelado manteve sua qualidade durante 3h após o descongelamento. A taxa de fertilização obtida com o sêmen in natura (74±6%) foi superior ao sêmen criopreservado (1,6 mL - 45±9% e 4,5 mL - 41±12%). Os dois criotubos não diferiram entre si neste parâmetro. Uma alta correlação significativa (p<0,05) foi observada entre a fertilização e a cinética espermática (MT - 89%; MP - 86%; VCL - 79%; VSL - 69% e VAP - 78%). Conclui-se que os criotubos de 1,6 e 4,5 mL podem ser utilizados na criopreservação do sêmen de tambaqui, sendo recomendado seu descongelamento a 60°C por 90s e seu uso em procedimentos de fertilização dentro de 3 horas após o descongelamento desde que mantido a 5°C
Cryopreservation of tambaqui (Colossoma macropomum) semen in large straws
No full textCryopreservation of fish semen is a key to optimization of reproductive management, the formation of germplasm bank and the development of genetic improvement programs. The success of this technique depends on the management and balance of several factors such as the collection, dilution, packaging, freezing and thawing. Tambaqui semen cryopreservation protocols have been developed using 0.5 mL straws on packaging. However, the high volumes of semen produced and the elevated taxes of fecundity are presented by this specie, it is necessary to use larger volume storage containers for application to large-scale production. The objective of this study was to establish a tambaqui semen cryopreservation protocol in large straw 4,0mL, from the definition of cryosolution, equilibration time and the best ratio between temperature and time semen thawing. The semen collected was diluted, packaged in large straws, frozen in liquid nitrogen which was conditioned in dry-shipper and stored in cryogenic cylinder at -196 °C. In the first experiment, different cryosolutions (M1 - 5% 5% methylglycol; M2 - 5% 5% methylglycol+ 5% egg yolk; M3 - 10% 5% methylglycol; M4 - 10% 5% methylglycol + 5% egg yolk; M5 - 15% 5% methylglycol; M6 - 15% de 5% methylglycol + 5% egg yolk) and three equilibration times (4, 20 and 40 minutes) were tested. In the second experiment, different relation between temperature and time thawing on sperm quality (30ºC for 50s - T1; 30ºC for 80s - T2; 60ºC for 25s - T3 e 60ºC for 40s - T4) were evaluated. In conclusion, this study showed that the ideal protocol for cryopreservation of tambaqui semen in large straw 4,0mL is made by diluting semen at a ratio of 1: 9 (v: v) in a medium composed of 5% methylglycol and 5% egg yolk. Both of them must have remained in contact with each other for 4 minutes until both were subjected to freezing in dry-shipper. The thawing of samples required to be performed in a water bath at 60 ° C for 25s.A criopreservação de sêmen de peixes é uma ferramenta para a otimização do manejo reprodutivo, a formação de bancos de germoplasma e o desenvolvimento de programas de melhoramento genético. O sucesso dessa técnica depende do domínio e o equilíbrio de vários fatores que envolvem os processos de coleta, diluição, envase, congelamento e descongelamento. Protocolos de criopreservação sêmen de tambaqui já foram desenvolvidos utilizando palhetas de 0,5mL no envase, no entanto, o elevado volume de sêmen produzido e alta fecundidade da espécie sugere o armazenamento em recipientes de maior volume para a aplicação na produção em larga escala. Com isso, o objetivo do presente estudo foi estabelecer um protocolo de criopreservação seminal do tambaqui em macropalhetas de 4,0mL, a partir da definição de um meio diluidor, tempo de equilíbrio e a melhor relação entre temperatura e o tempo de descongelamento do sêmen. O sêmen coletado foi diluído, envasado em macropalhetas, congelado em vapor de nitrogênio líquido no botijão dry-shipper e armazenadas em botijão criogênico a -196°C. No primeiro experimento, foram testadas diferentes composições do meio diluidor (M1 - 5% de metilglicol; M2 - 5% de metilglicol + 5% de gema de ovo; M3 - 10% de metilglicol; M4 - 10% de metilglicol + 5% de gema de ovo; M5 - 15% de metilglicol; M6 - 15% de metilglicol + 5% de gema de ovo) e três tempos de equilíbrio (4, 20 e 40 minutos). No segundo experimento, foram avaliadas diferentes velocidades de descongelamento do sêmen em banho-maria, sobre a qualidade espermática (30ºC por 50s - T1; 30ºC por 80s - T2; 60ºC por 25s - T3 e 60ºC por 40s - T4). Ao final do estudo concluiu-se, que o protocolo ideal para a criopreservação do sêmen do tambaqui em macropalhetas de 4,0mL consiste na diluição do sêmen na proporção de 1:9 (v:v) em um meio composto por 5% de metilglicol e 5% de gema de ovo, os quais devem permanecer em contato por 4 minutos até que sejam submetidos ao processo de congelamento em botijão dry-shipper. O descongelamento das amostras deve ser realizado em banho-maria a 60°C por 25s
Caracterização das subpopulações espermáticas do Tambaqui e sua correlação com a fertilidade
Get PDFThe analysis of sperm subpopulations is a relatively new approach that consists of evaluating the coexistence of different sperm grouped by similarity. This characterization allows us to explore the heterogeneity of existing sperm in a semen sample, so it is revealed your fertility potential. The aim of this study was to identify and characterize sperm subpopulations in semen tambaqui (C. macropomum) regarding the kinetics and evaluate its correlation with fertility, as well as analyzing the changes arising from the cryopreservation process in the distribution of sperm subpopulations. 59 767 sperm semen in natura and 50,680 of the thawed sperm of 61 fish through analysis in a computerized system (CASA) were evaluated. The kinetic data generated sperm were tabulated, analyzed, and evaluated relativized by the method of analysis of two-step cluster grouping. For correlation with fertilization, 15 animals with distinct sperm qualities were selected and evaluated for their performance in fertilization from seminal fresh samples. These procedures allowed the identification of three sperm subpopulations in semen in natura tambaqui, two of which are highly correlated with fertility. The first subpopulation corresponded to 28.81% of the total analyzed sperm and it was less abundant. Low values of curvilinear velocity - VCL: 58.92 mM / s, linearity - LIN: 23.15%, straightness - STR: 40.01% and beat cross frequency - BCF: 6.79 Hz characterized the sperm of this subpopulation as slow progressive non-linear and not, where no significant correlation was observed with fertility (r = 0.28). The second subpopulation represented 31.61% of the examined spermatozoa which were classified as rapid, non-linear, non-progressive and high beat cross frequency (LCV: 114.10 mM / s, LIN: 46.77% STR: BCF and 59.17%: 21.49 Hz), high positive correlation was observed with fertility (r = 0.93). Already a subpopulation 3, had a higher percentage of sperm analyzed (39.58%), characterized as fast, linear, progressive and high beat cross frequency (VCL: 134.11 mM / s, LIN: 81.41%, STR : BCF and 86.57%: 26.73 Hz), being also observed high positive correlation with fertility (r = 0.79). After thawing semen tambaqui, we could identify only two sperm subpopulations with distinct heterogeneity. The first subpopulation, representing 33.24% of the analyzed sperm which were characterized as slow, non-linear, non-progressive and low beat cross frequency (VCL: 52.96 mM / s, LIN: 20.70%, STR: and 41.70% BCF: 5,61Hz). The second subpopulation corresponded to 66.76% of the analyzed sperm which were characterized as fast, linear, progressive and high beat cross frequency (VCL: 121.57 mM / s, LIN: 69.02%, STR: 77, and 09% BCF: 26.00 Hz). It is concluded that semen tambaqui has three sperm subpopulations characterized by movement pattern, two of which are represented by rapid sperm directly related to fertility. The cryopreservation process reduces the number of sperm subpopulations and alters the pattern of linearity and progressivity of spermatozoa.A analise de subpopulacoes espermaticas e uma abordagem relativamente nova que consiste na avaliacao da coexistencia de diferentes espermatozoides agrupados por similaridade. Essa caracterizacao permite explorar a heterogeneidade dos espermatozoides existentes em uma amostra seminal, de forma que seja revelado o seu potencial de fertilidade. O objetivo do presente estudo foi identificar e caracterizar as subpopulacoes espermaticas no semen de tambaqui (C. macropomum) quanto a cinetica e avaliar sua correlacao com a fertilidade, bem como analisar as alteracoes decorrentes do processo de criopreservacao na distribuicao das subpopulacoes espermaticas. Foram avaliados 59.767 espermatozoides do semen in natura e 50.680 espermatozoides do semen descongelado de 61 peixes por meio da analise em sistema computadorizado (CASA). Os dados de cinetica espermatica gerados foram tabulados, analisados, relativizados e avaliados pelo metodo de analise de agrupamento two-step cluster. Para a correlacao com a fertilizacao, 15 animais com qualidades espermaticas distintas, foram selecionados e avaliados quanto ao seu desempenho na fertilizacao a partir de amostras seminais in natura. Esses procedimentos permitiram a identificacao de tres subpopulacoes espermaticas no semen in natura de tambaqui, sendo duas delas, altamente correlacionadas com a fertilidade. A subpopulacao 1 correspondeu a 28,81% do total de espermatozoides analisados e foi a menos abundante. Baixos valores de velocidade curvilinear . VCL: 58,92 Êm/s, linearidade . LIN: 23,15%, retilinearidade . STR: 40,01% e de frequencia de batimento flagelar . BCF: 6,79 Hz caracterizaram os espermatozoides desta subpopulacao como lentos, nao lineares e nao progressivos, onde nao foi observada correlacao significativa com a fertilidade (r= 0,28). A subpopulacao 2, representou 31,61% do total de espermatozoides analisados os quais foram classificados como rapidos, nao lineares, nao progressivos e com alta frequencia de batimento flagelar (VCL: 114,10 Êm/s, LIN: 46,77%, STR: 59,17% e BCF: 21,49 Hz), sendo observada alta correlacao positiva com a fertilidade (r= 0,93). Ja a subpopulacao 3, apresentou maior percentual de espermatozoides analisados (39,58%), caracterizados como rapidos, lineares, progressivos e com alta frequencia de batimento flagelar (VCL: 134,11 Êm/s, LIN: 81,41%, STR: 86,57% e BCF: 26,73 Hz), sendo observada tambem alta correlacao positiva com a fertilidade (r= 0,79). Apos o descongelamento do semen de tambaqui, foi possivel identificar apenas duas subpopulacoes espermaticas com homogeneidades distintas. A subpopulacao 1, representou 33,24% dos espermatozoides analisados os quais foram caracterizados como lentos, nao lineares, nao progressivos e com baixa frequencia de batimento flagelar (VCL: 52,96 Êm/s, LIN: 20,70%, STR: 41,70% e BCF: 5,61Hz). A subpopulacao 2 correspondeu a 66,76% dos espermatozoides analisados os quais foram caracterizados como rapidos, lineares, progressivos e com alta frequencia de batimento flagelar (VCL: 121,57 Êm/s, LIN: 69,02%, STR: 77,09% e BCF: 26,00 Hz). Conclui-se que o semen de tambaqui possui tres subpopulacoes espermaticas caracterizadas pelo padrao de movimento, sendo duas delas, representadas por espermatozoides rapidos, diretamente relacionados com a fertilidade. O processo de criopreservacao reduz o numero de subpopulacoes espermaticas e altera o padrao de linearidade e progressividade dos espermatozoides
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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