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Development of assisted reproductive technologies for ex-situ in vitro gene conservation in sheep
No full textThe current study involved three different experiments to assess the effects of epididymal spermatozoa (EPS) collection methods, ram breed, three (3) different commercial soy-lecithin-based semen extenders {Andromed® (AND), Bioxcell® (BIO), and OviXcell® (OVI)}, and two spermatozoa concentrations (400×106 vs 200×106 spermatozoa/ml) on the freezability of ram epididymal spermatozoa (REPS). Lastly, we evaluated the developmental kinetics of in vitro-produced sheep embryos fertilized with post-thaw REPS using ivf-Bioscience bovine media to enhance the conservation of local sheep breed genetic resources (GnR).
Fourteen pairs of testes from German Mutton Merino (Merino:7) and Hungarian Black Racka (Racka:7) rams collected from a slaughterhouse for Experiment I. Post-mortem REPS were retrieved from the cauda epididymides by either Slicing or Incision method. Fresh samples were extended to 200×106/ml, filled into mini straws and equilibrated at 5 oC for 2 hours. Freezing was performed manually in a Styrofoam box. The fresh and post-thaw REPS’s Standard motility (SMP) and kinematic parameters (KP) were assessed using a CASA. The collection method did not significantly affect REPS’s fresh and post-thaw SMP and KP. The Merino breed had significantly (p<0.05) higher testicular weight (TW); in contrast, the Racka breed had significantly (p<0.05) better fresh LIN, STR, BCF and ALH and higher post-thaw LIN and BCF values. The Merino has heavier testicles and significantly (p<0.05) better cryo-tolerance in total motility, while the Racka fresh and post-thaw REPS have more linear movement and presented significantly (p<0.01) higher cryo-tolerance in most of the KP than the Merino Breed.
In experiment II, the REPS were retrieved from nine adult rams’ testes of different breeds and diluted with each of the 3 extenders to both concentrations. Straws were frozen manually. SMP and KP were assessed by CASA, while spermatozoa viability, morphology and acrosomal integrity were evaluated using the Kovacs-Foote staining technique. The concentration did not significantly affect all the pre-freeze and post-thaw SMP and KP of REPS. The BIO and OVI had significantly higher pre-freeze and post-thaw BCF, post-thaw VAP and percentage of spermatozoa with intact head membranes than the AND. In contrast, the AND had a significantly lower percentage of REPS with tail defects than the BIO and OVI. The 400×106 spermatozoa/ml resulted in a significantly higher percentage of all intact head membranes than the 200×106 spermatozoa/ml.
Experiment III comprised five (5) programs involving 216 cumulus-oocyte complexes (COCs). The COCs were matured for 23-24 hours, while IVF with post-thaw REPS in ivf-Bovine bioscience media. Viable sheep embryo with good developmental competence: overall cleavage rate of 43.0 %, a morula of 40.0 %, and a blastocysts rate of 21.0 % were obtained, comparable to those reported in the literature.
In conclusion, breed significantly affects REPS cryo-tolerance, and either of the collection methods can be used to retrieve REPS without adverse effects. Freezing significantly increased tail defects and decreased the percentage of REPS with distal cytoplasmic droplets. Cryopreservation of REPS is recommended in 400×106 spermatozoa/ml concentration. All three extenders must be optimised to preserve viability, membrane integrity and better normal morphology of REPS. In vitro embryo production using post-mortem/abattoir-sourced gametes can be an alternative to MOET and ovum pick-up in cryo-banking of valuable local sheep breeds.hb
The recent state of cryopreservation techniques for ex-situ gene conservation and breeding purposes in small ruminants: A review
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The recent state of cryopreservation techniques for ex-situ gene conservation and breeding purposes in small ruminants: A review
Get PDFThe viewpoint of the recent cryopreservation techniques (CT) suggests the use of a reduced volume of cryopreservation solution, high concentration of cryoprotectants and ultra-rapid cooling and warming rates help to reduce cryo-injury and maximize the viability of the preserved animal genetic resources (AnGR). The CT had now become widely accepted as one of the best methods of choice for the ex-situ conservation of AnGR due to its high success rate recorded and no-invasive nature as compared to the conventional slow rate freezing (CSRF). Rapid advances and wide acceptability of the use of assisted reproductive technologies (ART’s) particularly artificial insemination (AI) in animal breeding had resulted in a greater loss of a large number of good quality genes in virtually almost all the native breeds of animals across the globe. Small ruminant (SR) animals are not an exception in such present predicaments situation of erosion and dilution of the valuable AnGR among the native breeds. As a result of this, 148 and 16 breeds of sheep and goats respectively have already become extinct in Europe and the Caucasus. In view of the aforementioned situation, the present review aimed at exploring some of the current states of development, roles played and potentials of CT in the conservation of SR genes and genome for the immediate and future breeding purposes for sustainable development. It basically covers; animal genetic resource, the need to conserve AnGR, tools for ex situ in vitro conservation of AnGR and recent developments in breeding and cryopreservation of SR AnGR.
Cryopreservation is playing a pivotal role in ex-situ gene conservation of AnGR. Decline in genetic diversity among SR breed population was high in Europe and the Caucasus. There is therefore, need for improvent on current stringent measures on conservation of AnGR in this region of the world
A review on the effect of endocrine disruptors on reproductive performance of small ruminant
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The status of conservation and management of indigenous sheep breeds in South Africa - A review
No full textIndigenous sheep breeds in South Africa play an important role in local food security and they are adapted to local conditions. Their genetic and cultural values have to be recognised for national importance. The conservation of these breeds is very critical as most of them are already classified as endangered. The South African government has the initiative to attempt the conservation of these animals; however, it comes with several challenges. In addition to funding, breed conservation demands farmers to understand and recognise the role of such breeds in society. This is especially crucial in the rural communal lands where breeds are kept. Farmers that raise indigenous breeds should be taught the necessity of maintaining the purity of these breeds. Indigenous sheep breeds in South Africa are not favored by the commercial farmers and thus they are more vulnerable. This review outlines the nature of sheep farming and the conservation status of four indigenous sheep breeds in South Africa. The effort and challenges that are met in current conservation arrangements are discussed. Moreover, we emphasise on the conservation techniques that are employed in South Africa
Alternative Opportunities to Collect Semen and Sperm Cells for Ex Situ In Vitro Gene Conservation in Sheep
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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
In vitro conservation of gametes: the way forward to conserve the genetic resources of autochthonous sheep breeds
Get PDFAssisted reproductive technologies (ARTs) significantly improved livestock productivity and reproductive performance and enabled elite parents to produce thousands of offspring globally. However, indiscriminate use ARTs, lack of information and materials on autochthonous sheep breeds (ASB) resulted in a loss of their genetic resources (GnR), thus shooting up the number of atrisk and extinct ASB globally. This problem is more in Europe and the Caucasus region, Africa, and Asia, according to the FAO 2005, 2017, and Sustainable Development Goals, 2022 reports. Considering the current economic challenges, in vivo gene conservation (INGC) is expensive and less sustainable. Therefore, an in vitro gene conservation (IVGC) can supplement the INGC for better efficiency and sustainability. The current review explored the pros and cons of ARTs on ASB’s GnR, the need to conserve their GnR through IVGC, and the prospects of the IVGC on ASB’s GnR conservation. Interestingly, Vitrification with reduced volume (e.g., cryotop) is the leading technique in oocyte cryopreservation, as it results in lower cryoprotectants toxicity, better oocyte viability, and pregnancy rates aside from being cheap and field-friendly than the other vitrification techniques. With oocyte and spermatozoa cryopreservation from the same breed, an extinct breed of interest can be regenerated in a single generation. However, oocyte cryopreservation holds a considerable prospect in IVGC, but the technique in sheep still needs improvements
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
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