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Endangered birds in UAE

Posted on 8. July, 2011.

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Avian Biology Research presents papers from the Conservation and Propagation of Endangered Species of Birds Symposium. Following threats to the existence of the houbara bustard, avian research centres were established in the Arabian Peninsula. Consequently, interspecific chimeras have been developed as a route to re-populating houbaras in their native environments.

Conservation of Houbara bustards using interspecifies chimeras

Ulrich Wernerya, Chunhai Liua, Vijay Baskara, Zhor Guerinechea, Kamal A. Khazanehdaria, Shazia Saleema, Jörg Kinnea, Renate Wernerya, Darren K. Griffinb and Il-Kuk Changa

aCentral Veterinary Research Laboratory (CVRL), PO Box 597, Dubai, UAE

bSchool of Biosciences, University of Kent, Canterbury CT2 7NJ, UK

Embryonic gonadal tissue was dissected individually from Houbara bustard embryos at eight days post-incubation. Houbara bustard gonadal cells containing gonadal primordial germ cells (gPGCs) were injected into the blood stream of White Leghorn chicken (Gallus gallus domesticus) embryos, producing 83/138 surviving male chimeric embryos, of which 35 chimeric roosters reached sexual maturity after 5 months. The incorporation and differentiation of Houbara bustard PGCs in chimeric chicken testis were assessed by PCR with Houbara bustard species-specific primers and 31.3% (5/16) gonads collected from the injected chicken embryos showed the presence of donor Houbara bustard cells. A total of 302 semen samples from 34 chimeric roosters were analyzed and eight were confirmed as germ line chimeras. Semen samples from these eight roosters were used to artificially inseminate three female Houbara bustards. Subsequently, 45 Houbara bustard eggs were obtained and incubated, two of which were fertile. One egg hatched as a male live born Houbara bustard and the other was female but died before hatching.

doi: 10.3184/175815511X13069389864397

Factors causing sex differences in birds

Arthur P. Arnold* and Yuichiro Itoh

Department of Integrative Biology and Physiology, University of California, Los Angeles Terasaki Life Science Building, 610 Charles Young Drive South, Los Angeles, California 90095-7239, USA

In recent years, increasing evidence suggests that sex differences in the phenotype of all tissues are influenced by the inequality of effects of sex chromosome genes in the two sexes.  In birds, genes on the Z chromosome are not well dosage compensated, so that most Z genes are expressed higher in ZZ male cells than in ZW female cells.  The sex difference in expression of Z and W genes is likely to cause sex differences within cells, in addition to the sex differences caused by different levels of testicular and ovarian hormones. The sexual imbalance in cell physiology has implications for aviculture and novel developments in the poultry industry.

doi: 10.3184/175815511X13070045977959

Freezing avian semen

Elisabeth Blesbois

INRA, UMR-PRC, 37380 Nouzilly, France

Semen cryopreservation is an important tool for the storage of reproductive cells used for the ex situ management of genetic diversity in birds. Recent advances in poultry semen cryopreservation technology have resulted in the emergence of cryobanking, which is now being developed in an increasing number of countries. In addition, semen freezing methods are now effective for various domestic and wild bird species, although species such as guinea fowls are still highly affected by the process. The methods of freezing avian semen now use a small number of cryoprotectants, (mainly glycerol, dimethyl or N-methylacetamide) and cell packaging (such as straws or pellets).  Temperature curves of freezing and thawing remain the most variable points as very slow or very rapid curves are sometimes used in the same species.  Specific features of bird reproductive physiology are very important for sperm cryopreservation and application. The characteristics of initial semen quality, including cell membrane properties, mobility capacity and ability to undergo the acrosome reaction are critical points. The specific features of the oviparity system of reproduction and the internal fertilization process affect the conditions of semen use. The in vivo storage of spermatozoa in the sperm storage tubules of the female genital tract, and the conditions of the drastic selection of sperm in the highly specialized female oviduct constitute major factors that are highly species-specific. These constraints involve adaptations of the semen media used for freezing and of the zootechnical parameters of semen use. This review highlights the main factors that are critical for the success of semen cryopreservation in bird species.


Potential for somatic nuclear transfer technology in domestic chickens

Atsushi Tajima

Graduate school of Life and Environmental Sciences, University of Tsukuba, Ibaraki 305-8572, Japan

The development of mammalian somatic nuclear transfer techniques by Wilmut et al. in 1997 provided a new option for conserving animal genetic resources; however, this technique cannot be applied directly to avian species due to the anatomical and physiological differences between avian and mammalian embryos. A basic strategy for producing nuclear transferred avian offspring with somatic nuclear transferred primordial germ cells (snt-PGCs) was described in 2002. Under this scenario, somatic nuclear offspring could be produced through germline chimeras by transferring snt-PGCs into the bloodstream of early chicken embryos. In the present study, a series of experiments have been carried out to produce somatic nuclear transferred chickens.

Doi: 10.3184/175815511X13069428755484

Falcon breeding in the Middle East and facility design considerations

David Le Mesurier

Nad Al Shiba Avian Reproduction Research Centre, PO Box 5175, Dubai, UAE

The captive breeding of falcons in the Middle East has been carried out since the mid 1970s. In this paper, we will look at the timeline for the development of breeding centers in the Middle East and design considerations used for one project built in the desert heat of Dubai.

Doi: 10.3184/175815511X13069438586652

Spermatogonial stem cells

M. Naito

National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan

Testicular gonocytes differentiate into spermatogonia, and spermatogonial stem cells could be established by culturing spermatogonia in vitro. Testicular and ovarian gonocytes were identified as relatively large cells in a population of gonadal cells. The proportions of testicular and ovarian gonocytes in the total gonadal cells were 0.94% and 0.75%, respectively, recognised as CVH-positive cells. The dissociated gonadal cells containing testicular or ovarian gonocytes were then transferred into recipient embryos. The presence of the donor-derived DNA was detected in the gonads of 20-day cultured recipient embryos in males and females, and also in the sperm samples obtained from the hatched male putative chimaeric chickens. In vitro culture of testicular and ovarian gonocytes was also attempted. Gonads were obtained from 19-day incubated chicken embryos and the dissociated gonadal cells were cultured in vitro. Non-adherent cells containing gonocytes were then collected and cultured further. It was confirmed that some of the testicular gonocytes proliferated in vitro. The proliferated testicular gonocytes occasionally formed cell colonies. However, no apparent proliferation was observed in the ovarian gonocytes in vitro. These results suggest that the testicular and ovarian gonocytes have the ability to enter the germline of recipient embryos, and that testicular gonocytes can be cultured and proliferated in vitro.


Improving rates of germline transmission in chimeric chickens using busulfan solubilised sustained-release emulsion

Takahiro Tagamia and Yoshiaki Nakamuraa,b

aNational Institute of Livestock and Grassland Science, Tsukuba, Ibaraki 305-0901, Japan

bFaculty of Agriculture, Shinshu University, Minamiminowa, Nagano 399-4598, Japan

The administration of a busulfan solubilised sustained-release emulsion was used to improve the efficiency of endogenous primordial germ cell (PGC) depletion in early chicken embryos. Busulfan was solubilised in N,N-dimethylformamide and diluted 10 fold in phosphate-buffered saline [PBS(–)]. The sustained-release emulsion was prepared by mixing equal amounts of busulfan solubilised solution and sesame oil using a filter. The appropriate time and dose of busulfan sustained-release emulsion administration were established to optimise our novel germline replacement technique. Injecting busulfan sustained-release emulsion into the yolk of recipient embryos at zero hours of incubation did not disturb the movement and proliferation of donor cells during the generation of germline chimeras. A dose of 100 µg of busulfan resulted in the greatest reduction of endogenous PGCs in embryonic gonads and the most successful hatchability of sterilised embryos. Test-cross analysis revealed that the germline transmission rate in busulfan treated chickens was significantly higher than in non-treated controls (99.5 versus 6.0 %). This unique and efficient germline transmission system has potential applications in the conservation of endangered and/or rare avian species.

Doi: 10.3184/175815511X13085702790617

Interspecific duck–chicken chimeras

Junshuang Gao, Jin Sha, Fang Yuan, Wenxin Zhang, Lei Rui, Xiaoyan Tang, Haitang Han, Yujing Shao, Haiwen Liu, Li Yan and Zandong Li*

State Key Laboratories for AgroBiotechnology, Department of Biochemistry and Molecular Biology, College of Biological Sciences, China Agricultural University, No. 2, Yuanmingyuan West Road, Beijing, 100193, P.R. China

The production of quail–Peking duck, Peking duck–quail and Maya duck–chicken chimeras by transferring donor (quail, Peking duck and Maya duck) blastoderm cells into the subgerminal cavity of the recipient (Peking duck, quail and chicken) eggs is described. Production of chimeras by transferring blastoderm cells into the recipient embryo should provide a basis for the investigation of fertilisation barriers in interspecies germline chimeras. It might help to protect endangered birds, contribute to further understanding of physiology and embryonic development in poultry, and provide a technical method for poultry transgenics.


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