Identification of the sex of Oriental white stork, Ciconia boyciana, by the polymerase chain reaction based on its sex chromosome-specific DNA sequences

Anthropogenic threats to the reintroduced population of Oriental storks in Japan: analysis of the causes of injury and death of 153 storks from 2005 to 2021

After the native population of Oriental stork (Ciconia boyciana) in Japan disappeared, a reintroduction project was implemented in 2005. All released storks and most wild-fledged storks were individually identified using colored rings on their legs. The size of the reintroduced population reached 256 by the end of 2021. In this study, we investigated the causes of stork injury and death in wild populations to clarify important medical issues for successful reintroduction. During the survey, 153 of 412 (78 released and 334 fledged storks) storks were injured or died between 2005 and 2021. At least 49.7% of the injuries and deaths were directly caused by human activities. Entanglement with pest control measures (such as bird- and beast-proofing nets) and accident with electrical and telecommunication equipment are two major causes of injury and death of reintroduced Oriental storks in Japan. It is important to recognize that these anthropogenic threats have a significant impact on the establishment and maintenance of the reintroduced populations of Oriental storks in Japan. Therefore, it is necessary to implement countermeasures against these threats to establish human and Oriental storks coexistence, which is a major goal of reintroduction.

Comparative Analysis of Gut Microbiota in Captive and Wild Oriental White Storks: Implications for Conservation Biology

The oriental white stork (Ciconia boyciana) is considered an endangered species based on the International Union for Conservation of Nature (IUCN) Red List. This study presents the first evidence on comparative analysis of gut microbial diversity of C. boyciana from various breeding conditions. To determine the species composition and community structure of the gut microbiota, 24 fecal samples from Tianjin Zoo and Tianjin Qilihai Wetland were characterized by sequencing 16S rRNA gene amplicons using the Illumina MiSeq platform. Firmicutes was found to be the predominant phylum. Analysis of community structure revealed significant differences in the species diversity and richness between the populations of the two breeding conditions. The greatest α-diversity was found in wild C. boyciana, while artificial breeding storks from Tianjin Zoo had the least α-diversity. Principal coordinates analysis showed that the microbial communities were different between the two studied groups. In conclusion, this study reveals the species composition and structure of the gut microbiota of oriental white storks under two breeding conditions, and our findings could contribute to the integrative conservation of this endangered bird.

Sex ratio of White Stork Ciconia ciconia in different environments of Poland

The aim of this study was to analyze the variation in sex ratio of White Stork Ciconia ciconia chicks from differentiated Poland environments. We took under a consideration the impact of Cd and Pb for establish differences among sex ratio in chicks. We also study multiplex PCR employment for establish gender considerations. We collected blood samples via venipuncture of brachial vein of chicks during 2006-2008 breeding seasons at the Odra meadows (SW-Poland; control), which were compared with those from suburbs (SW-Poland), and from copper smelter (S-Poland; polluted) and from swamps near Baltic Sea. We found differences among sex ratio in White Stork chicks from types of environment. Male participation in sex structure is importantly higher in each type of environment excluded suburban areas. Differences in White Stork sex ratio according to the degree of environmental degradation expressed by Cd and Pb and sex-environment-metal interactions testify about the impact of these metals upon sex ratios in storks. Simultaneously, as a result of multiplex PCR, 18S ribosome gene, which served as internal control of PCR, was amplified in male and female storks. It means that it is possible to use primers designed for chicken in order to replicate this fragment of genome in White Stork. Moreover, the use of Oriental White Stork Ciconia boyciana W- chromosome specific primers makes it possible to determine the sex of C. ciconia chicks. Many factors make sex ratio of White Stork changes in subsequent breeding seasons, which depend significantly on specific environmental parameters that shape individual detailed defense mechanisms.

PCR-based method for sex identification of Eastern sarus crane (Grus antigone sharpii): implications for reintroduction programs in Thailand

Due to human activity and a reduction in the size and quality of wetland habitats, populations of the Eastern sarus crane (Grus antigone sharpii) have declined dramatically across their range in Southeast Asia. Conservation efforts in Thailand have focused on reintroduction of the founders harboring the highest genetic diversity. One of the most important requirements to ensure the persistence of the reintroduced populations is a balanced sex ratio. In this study we tested three simple PCR-based methods which may be used for reliable sex identification in G. a. sharpii. The first method employs two combined primer sets based on a 0.6 kb EcoRI fragment (EE0.6). The second method is based on the intronic length polymorphism of the chromo-helicase DNA binding protein (CHD). The last technique relies on PCR-RFLP technique. The sex of six known and 24 unknown cranes were successfully identified by all three methods. These PCR-based sex identification methods are also useful for captive breeding management of G. a. sharpii.

Improved molecular assay for sex identification of the endangered crested Ibis (Nipponia nippon) based on the CHD1 gene and a sex-linked microsatellite locus

Sex Identification of monomorphic birds, especially endangered avian species, is essential for ecological study and biodiversity conservation. In this study, two popular primer sets of 2550F/2718R and P2/P8, which were designed to amplify different fragments of chromodomain-helicase-DNA binding protein 1 (CHD1) genes mapped on both Z and W chromosomes in birds, were used to identify for the first time the sex of individuals of the endangered species crested ibis (Nipponia nippon) in a large number of samples. An improved primer set of 2467F/2530R was re-designed to be specific to crested ibis following their conserved sequences derived from the 2550F/2718R primers. PCR products of the new primers were conveniently visualized with two bands of 552 base pairs (bp) and 358 bp for females, but a single band of 552 bp for males in routine 1.8% agarose gel. Similarly, the P2/P8 primer set amplified two fragments of 398 bp and 381 bp from females but one fragment of 398 bp from males; however, a high resolution involving 10% Polyacrylamide gel had to be employed to resolve the 17 bp insertions/deletions (in/dels) present between the two amplicons in females. In addition, a microsatellite locus NnNF05 was validated to be sex-linked and shown to be effective in the sexing of crested ibis, supporting its utility in non-invasive sampling. This study provides a rapid, convenient, and reliable molecular assay for improving sex identification in the monomorphic and monogamous crested ibis, and thus facilitates the selection of breeding pairs in captive programs and reintroduction initiatives.

Molecular and cytological characterization of SspI-family repetitive sequence on the chicken W chromosome

A genomic clone, pWS44, isolated from the chicken W chromosome-specific genomic library contained a partial (226-bp) sequence of a novel SspI-family repetitive sequence. A genomic clone, pWPRS09, containing a 508-bp SspI fragment (a repeating unit of the family) was subsequently obtained and sequenced. This 0.5-kb unit is tandemly repeated about 11,300 times. FISH to mitotic and lampbrush W chromosomes indicates that the SspI-family is located on the chromomere 6 between heterochromatic and distal non-heterochromatic regions on the short arm. The SspI-family sequence was proved to be a good positional marker in FISH mapping of active genes in the non-heterochromatic region on the lampbrush W chromosome. The presence of SspI-family repetitive sequence is limited to the genus Gallus (chickens and jungle fowls). The 0.5-kb repeating unit contains a 120-bp stretch of polypurine/polypyrimidine sequence (GGAGA repeats), shows no DNA curvature, and rapid electrophoretic mobility in 4% polyacrylamide gel at 4 degrees C. The SspI-family forms a relatively diffused chromatin structure in nuclei. These features are distinctly different from those of XhoI- and EcoRI-family sequences on the W chromosome. The total amount of non-repetitive DNA in the chicken W chromosome is estimated to be about 10 Mb.

Evolution of the avian sex chromosomes and their role in sex determination

Is it the female-specific W chromosome of birds that causes the avian embryo to develop a female phenotype, analogous to the dominance mode of genic sex differentiation seen in mammals? Or is it the number of Z chromosomes that triggers male development, similar to the balance mode of differentiation seen in Drosophila and Caenorhabditis elegans? Although definite answers to these questions cannot be given yet, some recent data have provided support for the latter hypothesis. Moreover, despite the potentially common features of sex determination in mammals and birds, comparative mapping shows that the avian sex chromosomes have a different autosomal origin than the mammalian X and Y chromosomes.

Determination of the complete nucleotide sequence and haplotypes in the D-loop region of the mitochondrial genome in the oriental white stork, Ciconia boyciana

The complete nucleotide sequence of the mitochondrial genome of the Oriental white stork, Ciconia boyciana, has been determined from captive storks by a novel method incorporating Long PCR and shotgun sequencing. 13 protein-coding genes, two ribosomal RNA genes and 22 transfer RNA genes were identified as in other vertebrate mitochondrial genomes. The position and direction of the NADH6 and tRNA-Glu genes were the same as previously reported for avian mitochondrial genomes. A 71 bp direct repeat and long CAAA repeat sequences were found at the 3' end of the D-loop region, together with SCB-1, SCB-2, SCB-3, and three TAS sequences. Direct sequencing of the PCR fragments in the D-loop region in 26 captive Oriental white storks originating from Japan, China, and Russia revealed nucleotide differences at 18 sites along 1,248 bp, and a total of nine haplotypes have been identified. It was found that one pair of individuals in the Japanese captive breeding program were of the same haplotype, suggesting that they were caught from the same nest. The pair has since been dissolved in consideration of the possibility of inbreeding depression.

The location of Z- and W-linked marker genes and sequence on the homomorphic sex chromosomes of the ostrich and the emu

Perhaps the most striking fact about early Cenozoic avian history some 70 million years ago was the rapid radiation of large, flightless, ground-living birds. It has been suggested that, for a time, there was active competition between these large terrestrial birds and the early mammals. Probably reflecting the above noted early start of Ratitae of the infraclass Eoaves, the presumptive sex chromosomes of their present day survivors, such as the emu and the ostrich, largely remained homomorphic. The signs of genetic differentiation between their still-homomorphic Z and W chromosomes were tested by using two marker genes (Z-linked ZOV3 and the gene for the iron-responsive element-binding protein) and one marker sequence of a part of a presumptive pseudogene (W-linked EE0.6 of the chicken). Their homologues, maintaining 71-92% identities to the chicken counterparts, were found in both the emu (Dromaius novaehollandiae) and the ostrich (Struthio camelus). Their locations were visualized on chromosome preparations by fluorescence in situ hybridization. In the case of the emu, these three marker sequences were localized on both members of the fifth pair of a female, thus revealing no sign yet of genetic differentiation between the Z and the W. The finding was the same with regard to both members of the fourth pair of male ostriches. In the female ostrich, however, the sequence of the gene for the iron-responsive element-binding protein was missing from one of the pairs, thus revealing the differentiation by a small deletion of the W from the Z.