Percorrer por autor "Asturiano, Juan F."
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- Another tool for chondrichthyan ex situ conservation: first-time chimaera monstrosa sperm cryopreservationPublication . García-Salinas, Pablo; Gallego, Victor; Asturiano, Juan F.Chondrichthyans, which comprises elasmobranchs (sharks and rays) and holocephalans (chimaeras), are one of the most endangered group of vertebrates on the planet. Ex situ conservation programs, such as captive breeding, are tools that can be used to improve the status of some of the most sensitive species belonging to these groups. However, the use of reproductive techniques is necessary when planning sustainable breeding programs in controlled environments. In recent years, our group has described the protocols necessary to achieve viable sperm extraction and its cryopreservation in 13 species. However, the use of these techniques in the holocephalan group has not yet been explored. Here, the process of obtaining viable sperm in a holocephalan species, Chimaera monstrosa, is presented for the first time. The sperm was obtained from animals recovered from bottom trawling bycatch. It was possible to recover sperm from both males (n = 3), using cannulation and abdominal massage, and females (n = 2), by directly accessing their oviductal glands. Sufficient sperm was obtained from the males to apply cryopreservation protocols developed for elasmobranchs. For this purpose, the sperm was diluted in an extender for elasmobranchs (1 sperm:9 extender) previously developed by our group. The cryopreservation of sperm was achieved through the addition of different cryoprotectants to the extender: methanol, dimethyl sulfoxide (DMSO) and fresh egg yolk. Samples were frozen inside a Styrofoam box using vapor of liquid nitrogen and preserved in liquid nitrogen. Sperm quality was assessed by studying motility and membrane integrity post-thawing. The initial motility and membrane integrity values were close to 54%. The best post-thawing motility values were obtained with a combination of 5% DMSO, 5% methanol and 10% egg yolk, which induced motility values close to 25% and membrane integrity values close to 24%. This is the first time that sperm from this group of animals has been cryopreserved, expanding our knowledge on their reproductive biology and the tools available for their conservation.
- Progress, challenges and perspectives on fish gamete cryopreservation: A mini-reviewPublication . Asturiano, Juan F.; Cabrita, Elsa; Horvath, AkosProtocols for the cryopreservation of fish gametes have been developed for many different fish species, in special, freshwater salmonids and cyprinids. Methods for sperm freezing have progressed during the last decades due to the increasing number of potential applications: aquaculture (genetic improvement programs, broodstock management, helping with species having reproductive problems), biotechnology studies using model fish species (preservation of transgenic or mutant lines), cryobanking of genetic resources from endangered species, etc. This mini-review tries to give an overview of the present situation of this area of research, identifying the main challenges and perspectives, redirecting the reader to more in-depth reviews and papers. (C) 2016 Elsevier Inc. All rights reserved.
- Reproduction techniques applied to chondrichthyans conservationPublication . García-Salinas, Pablo; Gallego, Victor; Asturiano, Juan F.Chondrichthyan fishes, which comprise sharks, rays, and chimaeras, are one of the most threatened groups of vertebrates. Given this situation, one possible strategy for the protection of these species could be the use of ex situ conservation projects. However, to develop sustainable ex situ conservation programs, captive breeding techniques, such as sperm extraction and its preservation, should be used. Two main obstacles must be overcome to develop these techniques: first, the lack of knowledge and the scarce previous work focused on the conservation of gametes from these animals; secondly, the peculiarities of the reproductive anatomy of each particular species. Through a detailed description of their reproductive anatomy, we have been able to develope the best techniques to obtain viable sperm from 17 species. Extraction has been performed in both live and dead animals, using cannulation, abdominal massage, and dissection. Exceptionally, we have even been able to recover viable sperm from the reproductive tract of females. Moreover, we have formulated artificial seminal plasma that can be used as an extender to maintain sperm motility for 36 days at 4 ◦C. By supplementing this extender with different combinations of cryoprotectants, i.e., methanol, dimethyl sulfoxide (DMSO), and fresh egg yolk, we were able to successfully cryopreserve (for the first time in most of these species) the sperm of 14 chondrichthyan species. Sperm samples were frozen inside a styrofoam box using the vapour of liquid nitrogen and were preserved in liquid nitrogen. The sperm quality was assessed by studying the motility and membrane integrity post thawing, demonstrating its effectiveness in the 14 species tested. In rays, the use of 10% DMSO or 10% methanol rendered post-thawing motility values higher than 40%. In sharks and the chimaera species, the best postthawing motility values were obtained with a combination of 5% DMSO, 5% methanol and 10% egg yolk, which induced mean values close to 35%. All this information broadens our knowledge on the reproductive techniques that can be applied to chondrichthyans, laying the foundations for the first cryobanks for their sperm.