1,720,979 research outputs found
Effect of testicle postmortem storage on goat frozen-thawed epididymal sperm quality as a tool to improve genebanking in local breeds
No full textThe interest to develop assisted reproductive technologies and cryobanking for farm animal genetic resource conservation has recently increased. However, cryopreservation for ex-situ management of genetic diversity sometimes is not routinely feasible, owing to the lack of facilities (AI centres, laboratories) and expertise near the local breed farming area. In these cases, epididymal sperm obtained from slaughtered or castrated animals, associated with the possibility of managing rather long periods between animal death, sperm recovery and freezing, would increase the opportunities to create semen storages. This investigation addresses the pre-freeze/post-thaw quality of goat epididymal sperm as a function of testicle storage temperature (environment or +5°C) and time elapsed between animal's death and sperm recovery (0, 24, 48, 72 h) to establish the optimal protocols for the recovery and cryopreservation of epididymal sperm in this species. Testicles of 50 mature bucks collected at the abattoir were divided in two groups: half of the testicles (n=50) were transported to the laboratory at environment temperature (E), whereas the remaining half (n=50) at a refrigeration temperature (R) of +5°C. In the two groups (E) and (R), one testicle from each pair was processed after slaughter forming the time 0 groups (0E and 0R). The contralateral testicle was processed after 24, 48 or 72 h of storage, at the corresponding temperature. Sperm motility and kinetic parameters, viability and morphology were assessed in pre-freeze and post-thaw samples. Until 48 h postmortem, both E and R temperatures are able to maintain good pre-freeze epididymal sperm quality. After 48 h postmortem, R temperature is fundamental to reduce epididymal sperm quality decay in pre-freeze samples. Moreover, testicle refrigeration also has a positive impact on post-thaw samples, allowing a lower decline through time considering total motility, kinetics parameters, sperm viability and sperm abnormalities. Therefore, when sperm cryopreservation is not immediately practicable, goat testicles should be transported and stored at 5°C up to a maximum of 48 h postmortem to ensure an acceptable sperm quality
Pellet cryopreservation for chicken semen : effects of sperm working concentration, cryoprotectant concentration, and equilibration time during in vitro processing
No full textThe aim of the study was to standardize the pellet cryopreservation procedure for chicken semen. Mericanel della Brianza male chicken breeders (Italian breed) were used. Pooled semen samples were processed according to the following conditions: (1) dilution in prefreezing extender to 1 versus 1.5 bill cells/mL sperm working concentration (SWC); (2) 6% versus 9% dimethyl acetamide (DMA) concentration (DMAco); (3) 1 versus 30minutes DMA equilibration (DMAeq) at 4°C. Sperm viability and motility were assessed in semen (four replicates/treatment) soon after collection (time 0), after DMAeq (time D), and after freezing/thawing (time FT). The recovery rates (%) of viable and motile sperm after freezing/thawing were also calculated. The low SWC (1 bill/mL) and the low DMAco (6%) indicated a positive significant effect on the proportion of motile sperm (1 bill/mL=53% vs. 1.5 bill/mL=48%; 6% DMA=55% vs. 9% DMA=47%). Very short DMAeq (1minute) did not significantly change sperm viability during processing (from time 0 to time D) before freezing whatever the DMAco, and, in contrast, the longer DMAeq showed a significant negative effect on sperm viability. The highest proportion of motile sperm was recorded in semen samples diluted to 1 bill/mL and added with 6% DMA; in this condition, DMAeq had no effect (57% 1minute and 61% 30minutes). Increasing SWC to 1.5 bill/mL and adding again 6% DMA, a significant effect of DMAeq was observed, and the higher proportion of motile sperm (58% vs. 43%) was recorded after 1minute DMAeq. A general decrease in sperm motility was shown in semen samples with 9% DMA (47% vs. 55%), and different conditions in SWC and DMAeq were not effective in the prevention of such decrease
Effect of docosahexaenoic acid and alpha-tocopherol enrichment in chicken sperm on semen quality, sperm lipid composition and susceptibility to peroxidation
No full textThe aim of the present experiment was to study the effect of fish oil and Vitamin E rich diets on semen production, sperm functions and composition in broiler breeders. The following parameters were measured: semen volume and concentration, sperm motility and viability, sperm susceptibility to induced peroxidation, sperm lipid and α-tocopherol contents. Dietary n - 3 PUFA were successfully transferred into spermatozoan phospholipid by fish oil feeding according to the following main features: (a) the C22:6n - 3 and C22:5n - 3 contents were increased, but C22:4n - 6 remained the peculiar and major polyunsaturate; (b) the content and proportion of total PUFA did not change; (c) the proportional increase of n - 3 PUFA was compensated by the decrease of n - 6 PUFA, an increase in the proportion of n - 9 fatty acids was also found. The sperm content of α-tocopherol was doubled increasing the dietary availability of the vitamin to 300 mg/kg of feed. The specific n - 3 PUFA and Vitamin E enrichment of chicken sperm affected cell functions. Significant interactions between the two treatments were also found for some parameters. The best sperm quality condition in control sperm (rich mainly in n - 6 PUFA) was found supplying 200 mg Vitamin E/kg of feed to the male breeders, and in contrast in n - 3 rich sperm supplying 300 mg Vitamin E/kg
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
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