As a well-known crustacean model species, the Chinese mitten crab Eriocheir sinensis presents spermatozoa with decondensed DNA. Our aim was to analyze structural distribution of the histone H3 and its acetylated lysine 9 (H3K9ac) during spermatogenesis for the mechanistic understanding of the nuclear decondensation of the spermatozoa in E. sinensis. Using specific antibodies, we followed the structural distribution and acetylated lysine 9 of the histone H3 during spermatogenesis, especially spermiogenesis, of E. sinensis. Various spermary samples at different developmental stages were used for histological immunofluorescence and ultrastructural immunocytochemistry. Our results demonstrate a wide distribution of the histone H3 and H3K9ac during spermatogenesis, including spermatogonia, spermatocytes, spermatids, and immature and mature spermatozoa except for absence of H3K9ac in the secondary spermatocytes. Especially during the initial stage of nuclear decondensation, histone H3 lysine 9 was acetylated and then an amount of H3K9ac was removed from within to outside of the nuclei of late spermatids. The portion of remaining H3K9ac was gradually transferred from the nuclei during the stages of spermatozoa maturation. Our findings suggest both the acetylation of histone H3 lysine 9 and the remain of H3K9ac to contribute to the nuclear decondensation in spermatozoa of E. sinensis.
The title compound, C13H6Br2O4, derived from xanthone, a fundamental structural framework of active ingredients in many medicinal plants, and was synthesized by bromination of 1,3-dihydroxyxanthen-9-one with N-bromosuccinimide. The molecular conformation is essentially planar, the dihedral angle between the benzene rings being 1.1 (4)°. This conformation is favorable for the formation of an intramolecular O—H⋯O hydrogen bond between a hydroxy group and the xanthone carbonyl group. In the crystal, molecules are associated into chains along the b-axis direction via C=O⋯H—O hydrogen bonds involving the other hydroxy group.
In the title compound, C22H13ClN2, the quinoxaline ring system is close to planar [maximum deviation = 0.061 (2) Å]. The phenyl ring at the 2-position and the phenyl ring of the phenylethynyl substituent make dihedral angles of 49.32 (7) and 11.99 (7) °, respectively, with the quinoxaline mean plane. The two phenyl rings are inclined to one another by 61.27 (9)°. In the crystal, molecules are linked by C—H⋯π and π–π interactions [centroid–centroid distances = 3.6210 (12) and 3.8091 (12) Å].
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