REPRODUCTION REVIEW Wildlife conservation and reproductive cloning Introduction (original) (raw)
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Wildlife conservation and reproductive cloning
Reproduction, 2004
Reproductive cloning, or the production of offspring by nuclear transfer, is often regarded as having potential for conserving endangered species of wildlife. Currently, however, low success rates for reproductive cloning limit the practical application of this technique to experimental use and proof of principle investigations. In this review, we consider how cloning may contribute to wildlife conservation strategies. The cloning of endangered mammals presents practical problems, many of which stem from the paucity of knowledge about their basic reproductive biology. However, situations may arise where resources could be targeted at recovering lost or under-represented genetic lines; these could then contribute to the future fitness of the population. Approaches of this type would be preferable to the indiscriminate generation of large numbers of identical individuals. Applying cloning technology to non-mammalian vertebrates may be more practical than attempting to use conventional reproductive technologies. As the scientific background to cloning technology was pioneered using amphibians, it may be possible to breed imminently threatened amphibians, or even restore extinct amphibian species, by the use of cloning. In this respect species with external embryonic development may have an advantage over mammals as developmental abnormalities associated with inappropriate embryonic reprogramming would not be relevant.
Cloning of an Endangered Species (Bos gaurus) Using Interspecies Nuclear Transfer
Cloning, 2000
Approximately 100 species become extinct a day. Despite increasing interest in using cloning to rescue endangered species, successful interspecies nuclear transfer has not been previously described, and only a few reports of in vitro embryo formation exist. Here we show that interspecies nuclear transfer can be used to clone an endangered species with normal karyotypic and phenotypic development through implantation and the late stages of fetal growth. Somatic cells from a gaur bull (Bos gaurus), a large wild ox on the verge of extinction, (Species Survival Plan Ͻ 100 animals) were electrofused with enucleated oocytes from domestic cows. Twelve percent of the reconstructed oocytes developed to the blastocyst stage, and 18% of these embryos developed to the fetal stage when transferred to surrogate mothers. Three of the fetuses were electively removed at days 46 to 54 of gestation, and two continued gestation longer than 180 (ongoing) and 200 days, respectively. Microsatellite marker and cytogenetic analyses confirmed that the nuclear genome of the cloned animals was gaurus in origin. The gaur nuclei were shown to direct normal fetal development, with differentiation into complex tissue and organs, even though the mitochondrial DNA (mtDNA) within all the tissue types evaluated was derived exclusively from the recipient bovine oocytes. These results suggest that somatic cell cloning methods could be used to restore endangered, or even extinct, species and populations.
Reproduction Fertility and Development, 2007
Somatic cell nuclear transfer (SCNT) can provide a unique alternative for the preservation of valuable individuals, breeds and species. However, with the exception of a handful of domestic animal species, successful production of healthy cloned offspring has been challenging. Progress in species that have little commercial or research interest, including many companion animal, non-domestic and endangered species (CANDES), has lagged behind. In this review, we discuss the current and future status of SCNT in CANDES and the problems that must be overcome to improve preand post-implantation embryo survival in order for this technology to be considered a viable tool for assisted reproduction in these species.
Reptile and amphibian conservation through gene banking and other reproduction technologies
Russian Journal of …, 2011
More than 300 of the~6180 known reptile species are critically endangered or endangered, with more than 200 known amphibian species extinct, and~1230 of the~6800 known amphibian species are critically endangered or endangered. To assure the survival of these species conservation breeding programs (CBPs) are being established. The perpetuation of genetic variation is required in both CBPs and in natural populations, to maintain health and reproduction, and to enable adaptation to environmental change. However, over time genetic variation is often lost in CBPs and in small or fragmented natural populations. Reproduction technologies including gene banking through the use of sperm cryopreservation can perpetuate genetic variation. These technologies are being applied to amphibian conservation, however, their development and use for reptiles has received only sporadic attention. We review the use of reproduction technologies for the conservation of amphibians and reptiles including the hormonal induction of sperm and oocytes, their use in artificial fertilization, and the potentials of sperm cryopreservation for gene banking. Support for the use of reproduction technologies, and the perpetuation of genetic variation of threatened amphibians and reptiles, will benefit from practical examples of the recovery of genetic variation from stored sperm, and its use to provide competent individuals for rehabitation programs and to supplement populations.
Reproductive biotechnologies for endangered mammalian species
Reproduction Nutrition Development, 2000
Assisted reproductive techniques (gamete cryopreservation, artificial insemination, embryo transfer, and in vitro fertilization) allow to propagate small fragmented populations of wild endangered species or domestic breeds. There are the best way for producing several offspring from selected genitors in order to avoid inbreeding depression. However, few mammalian species have been well studied for their reproductive biology whereas huge differences have been observed between these species. Furthermore, materials, methods and experimental designs have to be adapted for each case and each limiting factor (wildness, poor quantity of biological material, disparate locations). Genome resource banking is currently arising and the most applied reproductive biotechnology remains artificial insemination. Assisted reproductive techniques currently developed in domestic species (intracytoplasmic sperm injection, nuclear transfer) may offer new opportunities for the propagation of endangered species.
Role of reproductive technologies and genetic resource banks in animal conservation
Reviews of Reproduction, 1999
Irvine DS (1998) Relative impact of oxidative stress on the functional competence and genomic integrity of human spermatozoa Biology of Reproduction 59 1037-1046 Barratt EM, Deaville R, Burland TM, Bruford MW, Jones G, Racey PA and Wayne RK (1997) DNA answers the call of Pipistrelle bat species Nature 387 138-139 Barone MA, Roelke ME, Howard JG, Brown JL, Anderson AE and Wildt DE (1994) Reproductive characteristics of male Florida Panthers: comparative studies from Florida, Texas, Colorado, Latin America and North American Zoos Journal of Mammology 75 150-162 Campbell KHS, McWhir J, Ritchie WA and Wilmut I (1996) Sheep cloned by nuclear transfer from a cultured cell line Nature 380 64-66 Clouthier DE, Avarbock MR, Maika SD, Hammer RE and Brinster RL (1996) Rat spermatogenesis in mouse testis Nature 381 418-421 Curtis DJ, Zaramody A, Green DI and Pickard AR (1999) Non-invasive monitoring of reproductive status in wild mongoose lemurs (Eulemur mongoz): an investigation of faecal steroid excretion patterns Proceedings of the 7th World Conference on Breeding Endangered Species in Captivity May 1999, Cincinnati, OH Czekala NM and Callison L (1996) Pregnancy diagnosis in the black rhinoceros (Diceros bicornis) by salivary hormone analysis Zoo Biology 15 37-44 Digiano L, Nagle CA, Quiroga S, Paul N, Farinati Z, Torres M and Mendizabal AF (1992) Salivary progesterone for the assessment of the ovarian function in the Capuchin Monkey (Cebus apella) International Journal of Primatology 13 113-123 Donoghue AM, Johnston LA, Seal US, Armstrong DL, Simmons LG, Gross T, Tilson RL and Wildt DE (1992) Ability of thawed tiger (Panthera tigris) spermatozoa to fertilize conspecific eggs and bind and penetrate domestic cat eggs in vitro. Journal of Reproduction and Fertility 96 555-564 Dott HM and Utsi MNP (1973) Artificial insemination of reindeer, Rangifer tarandus. Journal of Zoology 170 505-508 Fennessy PF, Mackintosh CG and Shackell GH (1990) Artificial insemination of farmed red deer (Cervus elaphus) Animal Production 51 613-621 Garland P (1989) Artificial insemination of scimitar-horned oryx (Oryx dammah) Bulletin of Zoo Management 27 29-30
Cloning and Stem Cells, 2009
Recent accomplishments in the fields of nuclear transfer and genomics, such as the cloned offspring production from frozen mouse cells, cryopreserved at not too low temperatures without cryoprotectors; or the sequencing of wooly mammoth genome, have opened the opportunity for the revival of extinct species. As expected, they are receiving a lot of publicity in the media and also scientific attention. Furthermore, it was recently published the ''revival'' of the first extinct subspecie: the Pyrenean ibex (Capra pyrenaica pyrenaica), a wild goat extinct in 2000. This strengthens the field of cloning as it had been tarnished by induced pluripotent stem cells (iPS) and other methods of reprogramming. However, for biological conservation purposes, cloning is not generally accepted as an alternative for animal conservation, and there is an ongoing debate between reproductive scientists and conservation specialists. Although we believe that nuclear transfer technologies have an opportunity in conservation efforts for some species that are on the brink of extinction and that population status, geographical isolation, reproductive characteristics, and human pressure create a situation that is almost unsustainable. In this article we discuss the barriers in cloning mammoths and cloning controversies in conservation from a zoological perspective, citing the species that might benefit from nuclear transfer techniques in the arduous journey so as not to disappear forever from this, our world.
Conservation of wild animals by assisted reproduction and molecular marker technology
Wild animals are an integral component of the ecosystem. Their decimation due to abrupt natural calamities or due to gradual human intervention would be disastrous to the ecosystem and would alter the balance in nature between various biotic components. Such an imbalance could have an adverse effect on the ecosystem. Therefore, there is an urgent need to put an end to the ever increasing list of endangered species by undertaking both in situ and ex situ conservation using tools of modern biology, to ascertain the degree of genetic variation and reproductive competence in these animals. This review highlights the development and use of molecular markers such as microsatellites, minisatellites, mitochondrial control region, cytochrome b and MHC loci to assess the genetic variation in various Indian wild animals such as the lion, tiger, leopard and deer. The review also presents data on the semen profile of the big cats of India. Reproductive technologies such as cryopreservation of semen and artificial insemination in big cats are also highlighted.
First birth of an animal from an extinct subspecies (Capra pyrenaica pyrenaica) by cloning
Theriogenology, 2009
Two experiments have been performed to clone the bucardo, an extinct wild goat. The karyoplasts were thawed fibroblasts derived from skin biopsies, obtained and cryopreserved in 1999 from the last living specimen, a female, which died in 2000. Cytoplasts were mature oocytes collected from the oviducts of superovulated domestic goats. Oocytes were enucleated and coupled to bucardo's fibroblasts by electrofusion. Reconstructed embryos were cultured for 36 h or 7 d and transferred to either Spanish ibex or hybrid (Spanish ibex male  domestic goat) synchronized recipients. Embryos were placed, according to their developmental stage, into the oviduct or into the uterine horn ipsilateral to an ovulated ovary. Pregnancy was monitored through their plasmatic PAG levels. In Experiment 1, 285 embryos were reconstructed and 30 of them were transferred at the 3-to 6-cells stage to 5 recipients. The remaining embryos were further cultured to day 7, and 24 of them transferred at compact morula/blastocyst stage to 8 recipients. In Experiment 2, 154 reconstructed embryos were transferred to 44 recipients at the 3-to 6-cells stage. Pregnancies were attained in 0/8 and 7/49 of the uterine and oviduct-transferred recipients, respectively. One recipient maintained pregnancy to term, displaying very high PAG levels. One morphologically normal bucardo female was obtained by caesarean section. The newborn died some minutes after birth due to physical defects in lungs. Nuclear DNA confirmed that the clone was genetically identical to the bucardo's donor cells. To our knowledge, this is the first animal born from an extinct subspecies.