一氧化氮和繁殖控制

一氧化氮 (NO) ,被认为是动物体内重要的生物信使。NO是由 L -精氨酸在 NO合成酶的作用下合成的。NO合成酶在许多哺乳动物细胞中都有大量的同分异构体。近几年的研究结果表明 ,NO对繁殖功能的许多方面都有很大的影响。NO可控制下丘脑和垂体水平上的促性腺激素的分泌、LH峰的机制、性行为、性激素的合成、卵泡存活和排卵。本文对 NO控制下丘脑 -垂体 -性腺轴的关键分子机理进行综述     

ISSR and SSR markers reveal sex-specific DNA sequences in three <Emphasis Type="Italic">Calamus</Emphasis> species from India

Calamus species yields the raw materials for the cane industry. However, the extraction of the cane from the forests is being carried out indiscriminately without considering the sustenance of the species. Plants of both sexes should co-exist for reproductive success. The sex of Calamus plants can be identified only after flowering and hence proper planning of managed forestry practices cannot be accomplished. A study was carried out in this background and male specific ISSR markers for C. tenuis and C. flagellum and SSR markers for C. thwaitesii were identified. The diagnostic potential of these markers can be exploited to sex the Calamus species at the seedling stage for proper breeding and agroforestry management.     

Anabaena sensory rhodopsin: a photochromic color sensor at 2.0 A

Microbial sensory rhodopsins are a family of membrane-embedded photoreceptors in prokaryotic and eukaryotic organisms. Structures of archaeal rhodopsins, which function as light-driven ion pumps or photosensors, have been reported. We present the structure of a eubacterial rhodopsin, which differs from those of previously characterized archaeal rhodopsins in its chromophore and cytoplasmic-side portions. Anabaena sensory rhodopsin exhibits light-induced interconversion between stable 13-cis and all-trans states of the retinylidene protein. The ratio of its cis and trans chromophore forms depends on the wavelength of illumination, thus providing a mechanism for a single protein to signal the color of light, for example, to regulate color-sensitive processes such as chromatic adaptation in photosynthesis. Its cytoplasmic half channel, highly hydrophobic in the archaeal rhodopsins, contains numerous hydrophilic residues networked by water molecules, providing a connection from the photoactive site to the cytoplasmic surface believed to interact with the receptor's soluble 14-kilodalton transducer.