BackgroundThe Houbara bustard (Chlamydotis undulata) is a wild seasonal breeding bird populating arid sandy semi-desert habitats in North Africa and the Middle East. Its population has declined drastically during the last two decades and it is classified as vulnerable. Captive breeding programmes have, hitherto, been unsuccessful in reviving population numbers and thus radical technological solutions are essential for the long term survival of this species. The purpose of this study was to investigate the use of primordial germ cell-mediated chimera technology to produce viable Houbara bustard offspring.Methodology/Principal FindingsEmbryonic gonadal tissue was dissected from Houbara bustard embryos at eight days post-incubation. Subsequently, Houbara tissue containing gonadal primordial germ cells (gPGCs) was injected into 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 gPGCs in chimeric chicken testis were assessed by PCR with Houbara-specific primers and 31.3% (5/16) gonads collected from the injected chicken embryos showed the presence of donor Houbara cells. A total of 302 semen samples from 34 chimeric roosters were analyzed and eight were confirmed as germline chimeras. Semen samples from these eight roosters were used to artificially inseminate three female Houbara bustards. Subsequently, 45 Houbara eggs were obtained and incubated, two of which were fertile. One egg hatched as a male live born Houbara; the other was female but died before hatching. Genotyping confirmed that the male chick was a pure-line Houbara derived from a chimeric rooster.ConclusionThis study demonstrates for the first time that Houbara gPGCs can migrate, differentiate and eventually give rise to functional sperm in the chimeric chicken testis. This approach may provide a promising tool for propagation and conservation of endangered avian species that cannot breed in captivity.

The present study aimed to investigate the differentiation of chicken (Gallus gallus domesticus) primordial germ cells (PGCs) in duck (Anas domesticus) gonads. Chimeric ducks were produced by transferring chicken PGCs into duck embryos. Transfer of 200 and 400 PGCs resulted in the detection of a total number of 63.0 ± 54.3 and 116.8 ± 47.1 chicken PGCs in the gonads of 7-day-old duck embryos, respectively. The chimeric rate of ducks prior to hatching was 52.9% and 90.9%, respectively. Chicken germ cells were assessed in the gonad of chimeric ducks with chicken-specific DNA probes. Chicken spermatogonia were detected in the seminiferous tubules of duck testis. Chicken oogonia, primitive and primary follicles, and chicken-derived oocytes were also found in the ovaries of chimeric ducks, indicating that chicken PGCs are able to migrate, proliferate, and differentiate in duck ovaries and participate in the progression of duck ovarian folliculogenesis. Chicken DNA was detected using PCR from the semen of chimeric ducks. A total number of 1057 chicken eggs were laid by Barred Rock hens after they were inseminated with chimeric duck semen, of which four chicken offspring hatched and one chicken embryo did not hatch. Female chimeric ducks were inseminated with chicken semen; however, no fertile eggs were obtained. In conclusion, these results demonstrated that chicken PGCs could interact with duck germinal epithelium and complete spermatogenesis and eventually give rise to functional sperm. The PGC-mediated germline chimera technology may provide a novel system for conserving endangered avian species.

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The effect of interspecific egg white on the development of chicken embryos was investigated in a surrogate eggshell culture system. Egg yolks were separated from fertile White Leghorn chicken eggs and cultured in different egg whites from turkey (group TK), guineafowl (group GF), and duck (group DK), and chicken (group CK) was used as control. The viability of chicken embryos in groups CK, TK, GF, and DK after 3 d culture in system II was 98.3, 90.2, 96.1, and 91.1%. The whole contents (egg yolk and surrogate egg white) were further transferred into an eggshell from a 1.5 times heavier chicken egg with air space (system III), and incubated for further 16 d, before moving them to a hatcher. No significant difference between the 4 groups was found in their viabilities, which ranged between 72.9 and 81.3%, until 14 d postincubation (P > 0.05). After 21 d, the viability decreased to 60.4, 57.4, 50.0, and 27.7% in groups CK, TK, GF, and DK. The viability in group DK was significantly lower than in the other groups (P < 0.05). Weight loss in system III was approximately 12% in all the 4 groups without significant difference (P > 0.05). Hatchability of the chicken embryo was 60.4, 55.3, 47.9, and 19.1% in groups CK, TK, GF, and DK, respectively, and that in group DK was significantly lower than in the other groups (P < 0.05). There was no difference between the other groups (P > 0.05). These results show that chicken embryos can develop to hatch in duck, guineafowl, and turkey egg whites. However, the hatchability decreases according to the phylogenetic distance. The present study will provide a tool for manipulation of avian embryos and eventual conservation of endangered wild birds.

Background The banana (Musa sp., AAA) genome is constantly increasing due to high-frequency of somaclonal variations. Due to its large diversity, a conventional numerical and morphological based taxonomic identification of banana cultivars is laborious, difficult and often leads to subject of disagreements. Results Hence, in the present study, we used universal DNA barcode ITS2 region to identify and to find the genetic relationship between the cultivars and varieties of banana. Herein, a total of 16 banana cultivars were PCR amplified using ITS2 primer pair. In addition, 321 sequences which were retrieved from GenBank, USA, were used in this study. The sequences were then aligned using Clustal W and genetic distances were computed using MEGA V5.1. The study showed significant divergence between the intra- and inter-specific genetic distances in ITS2 region. BLAST1 and Distance methods proved that ITS2 DNA barcode region successfully identified and distinguished the cultivar and varieties of banana. Conclusion Thus, from the results of the present study, it is clear that ITS2 is not only an efficient DNA barcode to identify the banana species but also a potential candidate for enumerating the phylogenetic relationships between the subspecies and cultivars. This is the first comprehensive study to categorically distinguish the economically important banana subspecies and varieties using DNA barcodes and to understand its evolutionary relationship.

Cloning (somatic cell nuclear transfer) in avian species has proven unachievable due to the physical structure of the avian oocyte. Here, the sexual differentiation of primordial germ cells with genetic sex ZZ (ZZ PGCs) was investigated in female germline chimeric chicken hosts with the aim to produce uniparental offspring. ZZ PGCs were expanded in culture and transplanted into the same and opposite sex chicken embryos which were partially sterilized using irradiation. All tested chimeric roosters (ZZ/ZZ) showed germline transmission with transmission rates of 3.2%-91.4%. Unexpectedly, functional oogenesis of chicken ZZ PGCs was found in three chimeric hens, resulting in a transmission rate of 2.3%-27.8%. Matings were conducted between the germline chimeras (ZZ/ZZ and ZZ/ZW) which derived from the same ZZ PGCs line. Paternal uniparental chicken offspring were obtained with a transmission rate up to 28.4% and as expected, all uniparental offspring were phenotypic male (ZZ). Genotype analysis of uniparental offsprings was performed using 13 microsatellite markers. The genotype profile showed that uniparental offspring were 100% genetically identical to the donor ZZ PGC line, shared 69.2%-88.5% identity with the donor bird. Homozygosity of the tested birds varied from 61.5% to 84.6%, which was higher than the donor bird (38.5%). These results demonstrate that male avian ZZ PGCs can differentiate into functional ova in an ovary, and uniparental avian clones are possible. This technology suggests novel approaches for generating genetically similar flocks of birds and for the conservation of avian genetic resources.

We report the complete genome sequence of influenza virus H9N2 associated with a fatal outbreak among chickens in Dubai. All segments are clustered with avian H9N2 viruses circulating in the Middle East but distinct from those in southeast Asia. It is not a reassortant virus or transmitted from other regions.

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