ARGAÑARAZ Martin Eduardo
Frontiers Media SA
Lugar: Laussane; Año: 2021 p. 174
When we proposed this Research Topic to Frontiers in Veterinary Science, we aimed to invite andcongregate the best of the ongoing research that expands our current understanding of reproductivebiology in South American camelids (SACs). We did not pursue this only as a way to communicateamong the scientific community researching in the field but also to share the fascinating aspectsof reproduction in these species to a broad audience, including practitioners and colleaguesworking on education, conservation, and applied reproduction. In this Research Topic, we receivedcontributions that include a mini-review and several original research articles encompassingfundamental aspects of reproductive physiology and applied reproductive biotechnologies.SACs are species displaying unique reproductive features, many of which still are notunderstood; examples of these are their induced ovulatory mechanism and laterality of gestation.In this Research Topic, Berland et al. report neuroanatomical aspects of brain GnRH andkisspeptin neurons in female llamas; these neuropeptide-synthesizing cells orchestrate the release ofgonadotrophic hormones that control follicle development and ovulation. A second contributionby Gallelli et al. characterize the temporal association between follicular waves and circulatingconcentrations of estradiol and insulin grow factor-1 in llamas, showing that the rise of bothhormones parallels the development of follicular waves. In another study, Bianchi et al. reportevidence of dose-dependent estradiol-induced ovulation in llamas, resignifying the potential role ofestradiol in the ovulatory mechanism of SACs. In another piece of original research, Norambuenaet al. report that alpacas under moderate energy restriction negatively affect body condition scoreand CL size, but this does not result in significant changes in CL vascularization and progesteroneconcentrations. Finally, a study by Ratto et al. show that the ovulation laterality and intrauterineembryo location do not induce asymmetrical differences of the mesometrial and endometrialvascularization area of uterine horns during the first 30 days of gestation.Several pieces of evidence have shown that the beta-nerve growth factor (β-NGF) ?which is alsoimplicated in ovulation in SACs? exerts pivotal roles in the reproductive biology of SACs. In thisline, Valderrama et al. show that β-NGF enhances the expression of genes involved in angiogenesisand progesterone synthesis as well as progesterone output in preovulatory llama granulosa cells invitro. After conception, more than 90% of the gestations occur in the left uterine horn in SACs; astudy conducted by Barraza et al. characterize the bilateral horn gene and immunohistochemicalspatial expression of β-NGF and its receptor, TrkA, in the endometrium of non-pregnant and earlypregnant alpacas; the gene expression of the angiogenic factor VEGFA and number of vessels wasalso assessed.Closing the set of physiological aspects of reproduction in SACs, El Zawam et al. determineserum testosterone concentrations in response to administration of human chorionic gonadotropin(hCG) and its correlation with testicular weight in alpacas of different age The lack of understanding of the peculiar reproductivecharacteristics of SACs has impeded to make substantialimprovement of their low reproductive rates. It is essential toimprove and develop new strategies that increase reproductiveefficiency, and so the development of biotechnologies is necessaryto fulfill these objectives. For example, semen cryopreservationhas low efficiency, and when artificial insemination is performedwith it, poor results are obtained, affecting the advances ingenetic progress and selection. Here, we received a set of differentstudies related to reproductive biotechnologies in female andmale SACs. This set opens with a review by Morrell andAbraham about semen collection and handling in SACs. Originalresearch conducted by Zampini, Castro-González et al. reportelectron microscopy ultrastructural alterations of llama spermduring cooling and freezing, using a conventional camelid semencryopreservation protocol. Another study by Carretero et al.shows that the air-drying process has a negative effect on llamasperm DNA. Finally, Valdivia et al. report cryopreservation ofalpaca testicular tissue and isolated testicular cells.Several contributions aimed to develop strategies to enhancethe performance of cryopreserved semen were received in thisResearch Topic. In one of these, Sari et al. report that theaddition of β-NGF significantly increases the percentage oftotal motility and vigor of post-refrigerated sperm. Anotherstudy by Guillén Palomino et al. evaluate the efficiency ofAndrocoll-ETM to separate llama sperm from seminal plasma andfreezing extender in frozen-thawed semen, demonstrating theirseparation while preserving the viability, membrane function,and acrosome integrity. In the same area, Bertuzzi et al. comparea non-commercial extender with egg yolk and the commercialextender AndromedR with and without egg yolk for coolingalpaca sperm obtained from diverted deferent ducts. A studyby Aisen et al. investigated the effect of whole seminal plasmaaddition to alpaca spermatozoa after the freezing-thawingprocess on dynamic and morphological parameters and anartificial insemination trial. Closing the set of contributionsfocused on semen cryopreservation, a study conducted by Lutzet al. report a field-efficient technique for cryopreservationof alpaca preimplantation embryos using a modified horsevitrification protocol.In the subject of female reproductive biotechnology, Zampini,Veiga et al. report the development of a synchronization andsuperstimulation protocol for embryo donors in llamas showingthat a protocol based on GnRHa, PGF2α, and eCG allowsa fixed-timed mating without the use of ultrasonography. Inanother contribution of Zampini, Gallelli et al. using colorDoppler ultrasonography, they show that the uterine bloodflow (UBF), but not corpus luteum blood flow (CLBF), maybe a useful predictor for early pregnancy diagnosis in llamas 8days post-mating.The papers presented in this Research Topic provide newinsights into different aspects of reproductive biology of SACsand also demonstrate the efforts of the current research toprovide a better understanding of their peculiarities that, inturn, will allow overcoming challenges in applied reproductionin SACs.We would like to thank all the authors who contributedto this Research Topic and express our gratitude to theeditors, reviewers, and staff of Frontiers in Veterinary Sciencethat made possible this Research Topic in Reproductionin South American Camelids. Finally, we also extend ourthanks to Frontiers Media for the fee waivers providedwhich supported some of the contributions presented in thisResearch Topic.