Conservation of Avian Genetic Resources

Abstract

Conservation of avian genetic resources is important, as 13.0% (1,313/10,064) of known avian species are currently categorized as endangered by the International Union for Conservation of Nature and Natural Resources (IUCN, 2012). Development of an integrated system for conservation of avian genetics is necessary; however, germplasm conservation systems developed for mammals cannot be applied directly to avians, primarily due to the unique anatomical and physiological characteristics of the avian egg. Thus an alternative strategy for conservation of oviparous species of animals must be developed. Recent technological developments for producing germline chimeras by the transfer of primordial germ cells into recipient embryos has enabled the conservation and retrieval of chicken genetic resources in their complete form. Furthermore, the possibility of propagating endangered wild birds through interspecies germline chimeras has been proposed.In the present review, the current status of avian genetic resource conservation is presented with a focus on the following 4 topics: 1) semen cryopreservation, 2) germline chimeras, 3) somatic nuclear transfer, and 4) other related technologies.

Isolation and Number of Gonadal Primordial Germ Cells (Gonadal PGCs) on the Stages of Early Embryonic Development of KUB Chicken

“…The results were in line with the results reported by Nakajima et al (2011;2013) in White Leghorn (WL) and Rhode Island Red (RIR) chickens. The result also confirmed that PGCs isolation from gonad was easier and better with larger number of collected PGCs compared to the isolation of circulated PGCs.…”

“…The unique migration pathway of PGCs provides a possibility to isolate subsequent PGCs based on their locations. Primordial germ cells can be isolated from X-stage blastoderm, blood at 2.5-3-day-old embryos (stages 13-17 HH), or gonads at 5.5-6-day-old embryos (stages 26-28 HH) (Chojbacka-Puchta et al, 2012;Tajima, 2013). Numerous studies had reported the isolation and collection of PGCs from gonadal embryos (Nakamura et al, 2011;Nakajima et al, 2011;Nakajima et al, 2016).…”

Expression of GFP Gene in Gonads of Chicken Embryos by Transfecting Primordial Germ Cells <i>in vitro </i>or <i>in vivo </i>using the PiggyBac Transposon Vector System

“…Primordial germ cells (PGCs) are progenitor cells of ova and spermatozoa and are one of the most appropriate cells for germline manipulation in chickens (Kuwana, 1993;Tajima, 2002Tajima, , 2013Naito, 2003Naito, , 2015. Exogenous DNA could be introduced transiently into the gonads of recipient embryos by transfecting freshly collected PGCs in vitro and then transferring them to recipient embryos (Naito et al, 1998).…”

Embryo Manipulation in Chickens

“…Preservation of avian genetic resources was, therefore, conducted only by preserving spermatozoa (Tajima, 2013), and preservation of female gametes was impossible.…”

“…These techniques have been improved and established as a system for chicken germline manipulation. The author reviewed the progress of chicken embryo manipulation (Naito, 2003a, b, c), and further progress in this field has been reported in recent reviews (Lavial et al, 2006;Lavial and Pain, 2010;Han, 2009;Glover and McGrew, 2012;Intarapat and Stern, 2013;Nakamura et al, 2013;Nishijima and Iijima, 2013;Park et al, , 2014Tajima, 2013). This review, therefore, focuses on several topics involved in chicken embryo manipulation.…”