Using a comprehensive transcriptome analysis, a Z chromosomelinked chicken homolog of hemogen (cHEMGN) was identified and shown to be specifically involved in testis differentiation in early chicken embryos. Hemogen [Hemgn in mice, EDAG (erythroid differentiation-associated gene protein) in humans] was recently characterized as a hematopoietic tissue-specific gene encoding a transcription factor that regulates the proliferation and differentiation of hematopoietic cells in mammals. In chicken, cHEMGN was expressed not only in hematopoietic tissues but also in the early embryonic gonad of male chickens. The male-specific expression was identified in the nucleus of (pre)Sertoli cells after the sex determination period and before the expression of SOX9 (SRY-box 9). The expression of cHEMGN was induced in ZW embryonic gonads that were masculinized by aromatase inhibitor treatment. ZW embryos overexpressing cHEMGN, generated by infection with retrovirus carrying cHEMGN, showed masculinized gonads. These findings suggest that cHEMGN is a transcription factor specifically involved in chicken sex determination.bird | gonadal differentiation

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High pressure and high temperature experiments on CaSiO 3 , FeSiO 3 , MnSiO 3 and CoSiO 3 using a laser-heated diamond anvil cell combined with synchrotron X-ray diffraction were conducted to explore the perovskite structure of these compounds and the transition to the post-perovskite structure. The experimental results revealed that MnSiO 3 has a perovskite structure from relatively low pressure (ca. 20 GPa) similarly to CaSiO 3 , while the stable forms of FeSiO 3 and CoSiO 3 are mixtures of mono-oxide (NaCl structure) + high pressure polymorph of SiO 2 even at very high pressure and temperature (149 GPa and 1800 K for FeSiO 3 and 79 GPa and 2000 K for CoSiO 3 ). This strongly suggests that the crystal field stabilization energy (CFSE) of Fe 2+ with six 3d electrons and Co 2+ with seven 3d electrons at the octahedral site of mono-oxides favors a mixture of mono-oxide + SiO 2 over perovskite where Fe 2+ and Co 2+ would occupy the distorted dodecahedral sites having a smaller CFSE (Mn 2+ has five 3d electrons and has no CFSE).The structural characteristics that the orthorhombic distortion of MnSiO 3 perovskite decreases with pressure and the tolerance factor of CaSiO 3 perovskite (0.99) is far from the orthorhombic range suggest that both MnSiO 3 and CaSiO 3 perovskites will not transform to the CaIrO 3 -type post-perovskite structure even at the Earth's core-mantle boundary conditions, although CaSiO 3 perovskite has a potentiality to transform to the CaIrO 3 -type post-perovskite structure at still higher pressure as long as another type of transformation does not occur.

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Assortative mating is an important pre‐mating isolation mechanism that has been observed in some wild populations of seabirds. The Short‐tailed Albatross Phoebastria albatrus is a globally Vulnerable seabird that breeds mainly on Torishima and the Senkaku Islands in the north‐western Pacific Ocean. Our previous studies suggested that two genetically distinct populations exist, one on Torishima and the other on the Senkaku Islands. Recently, however, several un‐ringed birds in subadult plumage have been observed breeding on Torishima in the Hatsunezaki colony. As almost all birds hatched on Torishima since 1979 have been ringed, the natal site of the un‐ringed birds was suspected to be the Senkaku Islands. Genetic differences between the two populations would reveal the natal sites of un‐ringed birds. By observing the ring status (ringed or un‐ringed) of mating pairs and analysing the mitochondrial DNA (mtDNA) control region 2 of un‐ringed birds, we assessed whether birds that originated from Torishima and the Senkaku Islands achieved pre‐mating isolation. There was a small number of pairs on Torishima that consisted of one ringed and one un‐ringed bird, but the observed number was significantly lower than that expected if ringed and un‐ringed birds mated randomly. Furthermore, mtDNA analyses of nine un‐ringed birds demonstrated that all belonged to a particular haplotype clade from the Senkaku Islands. These results show that birds from Torishima and the Senkaku Islands mate assortatively but that there is incomplete pre‐mating isolation between birds from the two island groups. The pre‐mating isolation of these two populations of Short‐tailed Albatross could arise from differences in the timing of breeding and incompatibility in mating displays. As the divergence between the two populations is unlikely to be sufficient to achieve complete post‐mating isolation, the two groups are likely to be hybridizing. Further studies using molecular and/or behavioural analyses would be required to reveal the evolutionary significance of hybridization between these two populations.

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Restoration or establishment of colonies using translocation and hand-rearing can be an effective tool for conserving birds. However, well-designed post-release evaluation studies for long-lived species are rarely implemented. We investigated the attendance and breeding attempts of hand-reared short-tailed albatross (STAL) Phoebastria albatrus chicks (n = 69) translocated to a historic breeding island in the Ogasawara Islands, 350 km from the source colony, for 8 consecutive years after the first translocation. Thirty-nine percent of hand-reared birds (n = 27) returned to the translocation site at least once per breeding season, of which 67% (n = 18) also visited the natal island. The number of hand-reared birds returning each year was lower at the translocation site (mean: 0.3-2.3 birds per day) versus the natal island (0.4-3.5 birds per day). The first breeding attempt occurred 5 years after the first translocation. Three pairs (producing three chicks) recruited to the translocation site or neighboring islands and five pairs (producing nine chicks) recruited to the natal island by 8 years after the first translocation. Every hand-reared bird that raised a chick paired with a naturally reared bird. At the translocation site and neighboring islands, two hand-reared birds paired with a mate from the natal island and a breeding colony 1850 km away, respectively, while the parents of the third chick were unknown. Their breeding at the translocation region was observed among conspecific social attractants (decoys, audio playback; one pair) or congeners (two pairs). Our preliminary results suggest that even though more translocated and hand-reared albatrosses visited and recruited to their natal island compared to the translocation site, the early re-establishment of breeding by short-tailed albatrosses in the Ogasawara Islands 80 years after extirpation would not have occurred without the initial translocation effort. Further study is needed, however, to fully understand formation of breeding colonies beyond conspecific attraction and philopatry.

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