Gch在喋啶代谢通路中参与鱼类体色形成的研究

鸟苷三磷酸环化水解酶 (GTP cyclohydrolase,Gch)是具有GTP-cyclohydro结构域的蛋白酶,广泛存在于脊椎动物和无脊椎动物中。哺乳动物和鸟类中只具有Gch1,硬骨鱼类和两栖动物中Gch1存在旁系同源的Gch2和Gch3,且功能存在差异。Gch是以鸟苷三磷酸为底物,最终形成四氢生物蝶呤(tetrahydrobiopterin,BH4)的限速酶,而BH4是芳香族氨基酸羟化酶必须的辅助因子,参与多种激素和神经递质的合成。Gch是催化各种蝶呤生物合成的起始步骤,例如皮肤色素、眼色素、甲氨蝶呤、叶黄酸和BH4等,在体内一系列生理病理过程中发挥重要作用。Gch的生理功能与BH4的生物合成有着不可分割的联系,作为BH4生物合成的唯一限速酶,其活性可作为神经元和色素细胞的发育指示物,也是研究色素形成和神经递质生物合成的重要标志。目前,Gch在肿瘤和心血管等疾病的发病机制方面已获得广泛关注和解析,而色素合成和体色调控的作用研究多集中在昆虫方面,在硬骨鱼类中较少。因此,本文将重点对Gch基因、蛋白质、功能以及在鱼类体色方面中的作用进行总结归纳,对深入分析Gch在鱼类体色形成中的作用及后期鱼类体色改良具有重要的指导意义。     

Corticosterone regulates multiple colour traits in Lacerta [Zootoca] vivipara males

Ornamental colours usually evolve as honest signals of quality, which is supported by the fact that they frequently depend on individual condition. It has generally been suggested that some, but not all types of ornamental colours are condition dependent, indicating that different evolutionary mechanisms underlie the evolution of multiple types of ornamental colours even when these are exhibited by the same species. Stress hormones, which negatively affect condition, have been shown to affect colour traits based on different pigments and structures, suggesting that they mediate condition dependence of multiple ornament types both among and within individuals. However, studies investigating effects of stress hormones on different ornament types within individuals are lacking, and thus, evidence for this hypothesis is scant. Here, we investigated whether corticosterone mediates condition dependence of multiple ornaments by manipulating corticosterone levels and body condition (via food availability) using a two‐factorial design and by assessing their effect on multiple colour traits in male common lizards. Corticosterone negatively affected ventral melanin‐ and carotenoid‐based coloration, whereas food availability did not affect coloration, despite its significant effect on body condition. The corticosterone effect on melanin‐ and carotenoid‐based coloration demonstrates the condition dependence of both ornaments. Moreover, corticosterone affected ventral coloration and had no effect on the nonsexually selected dorsal coloration, showing specific effects of corticosterone on ornamental ventral colours. This suggests that corticosterone simultaneously mediates condition dependence of multiple colour traits and that it therefore accounts for covariation among them, which may influence their evolution via correlational selection.     

Three-dimensional soft tissue preservation revealed in the skin of a non-avian dinosaur

The most commonly preserved soft tissues associated with ornithischian dinosaurs are skin remains. The apparent resistance of hadrosaur skin to decay, and its abundance in the fossil record relative to that of other tetrapods, has been attributed to factors such as thickness and composition. Here we report additional intrinsic factors within hadrosaur skin: 3D-preserved eumelanin-bearing bodies, dermal cells and blood vessel fragments in an organic matrix composed of protein fossilization products. The skin is much thinner than that of living mammals of similar size. It is likely that the preservation of hadrosaur skin is related to the arrangement of the layers composing it.     

Characterisation of Bacillus thuringiensis mutant highly producing melanin pigment and active against potato tuber moth

The bacteria Bacillus thuringiensis mutant is highly producing melanin pigment with increased ultra violet resistance and insecticidal activity against the potato tuber moth Phthorimaea operculella (Zeller). The results showed that the high decrease of crystal protein formation rate ranged from 100% (B.t.EMS-M2 and B.t.EMS-M6) to 91.82% (B.t.EMS-M9). The EMS–UV-induced mutants (B.t.EMS–UV-2h-1, B.t. EMS–UV-2h-2, B.t.EMS–UV-2h-3, B.t.EMS–UV-2h-5, B.t.EMS–UV-4h-1, B.t.EMS–UV-4h-3 and B.t.EMS–UV-6h-2) showed 100% decrease in the crystal protein formation. Results also showed that the growth rate of B. thuringiensis isolates was detected by measuring the light absorption of culture broth (BP media at pH 8) at the wavelength of 600 nm. The absorbance values of the standard melanin were 2.055 and 0.134 at wavelengths of 226.5 and 602 nm, respectively. This means that the maximum absorbance at wavelength was 226.5 nm, this result is similar to that of the synthetic melanin which has the absorbance of 226 nm. Our experiments detected that the pigment extracted from the mutant isolate B.t.EMS-M3 (EMS-induced mutant) gave the maximum value of absorbance (2.615) at wavelength of 227.5 nm that was similar to standard melanin which gave absorbance value about 2.055 at a wavelength of 226.5 nm. This may be due to the genetic alterations that happened to the mutant isolates due to the mutation by EMS or/and UV irradiation.     

Phytochemical potential of Daphne gnidium in inhibiting growth of melanoma cells and enhancing melanogenesis of B16-F0 melanoma

In this study, we have investigated inhibitory capacity of ethyl acetate, total oligomer flavonoid (TOF), aqueous extracts and beta amyrin acetate, a triterpene isolated from ethyl acetate extract obtained from leaves of Daphne gnidium, on mouse melanoma (B16-F0 and B16-F10 cells) proliferation. Influence of these products on percentage cell distribution in cycle phases and melanogenesis was also studied. Cell viability was determined using the 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and flow cytometry was used to analyse effects of tested compounds on progression through the cell cycle. In addition, amounts of melanin and tyrosinase were measured spectrophotometrically at 475 nm. Ethyl acetate, TOF and aqueous extracts exhibited significant anti-proliferative activity after incubation with the two types of tumour skin cells B16-F0 and B16-F10. Furthermore, cell cycle analysis revealed that cells treated with ethyl acetate and TOF extracts were arrested predominantly in G2-M phase. Ethyl acetate extract has also the ability to enhance melanogenesis and tyrosinase activity of B16-F0 melanoma cells. Copyright © 2012 John Wiley & Sons, Ltd.     

Albinism in phylogenetically and geographically distinct populations of Astyanax cavefish arises through the same loss-of-function Oca2 allele

The Mexican tetra, Astyanax mexicanus, comprises 29 populations of cave-adapted fish distributed across a vast karst region in northeastern Mexico. These populations have a complex evolutionary history, having descended from ‘old'' and ‘young'' ancestral surface-dwelling stocks that invaded the region ∼6.7 and ∼2.8 MYa, respectively. This study investigates a set of captive, pigmented Astyanax cavefish collected from the Micos cave locality in 1970, in which albinism appeared over the past two decades. We combined novel coloration analyses, coding sequence comparisons and mRNA expression level studies to investigate the origin of albinism in captive-bred Micos cavefish. We discovered that albino Micos cavefish harbor two copies of a loss-of-function ocular and cutaneous albinism type II (Oca2) allele previously identified in the geographically distant Pachón cave population. This result suggests that phylogenetically young Micos cavefish and phylogenetically old Pachón cave fish inherited this Oca2 allele from the ancestral surface-dwelling taxon. This likely resulted from the presence of the loss-of-function Oca2 haplotype in the ‘young'' ancestral surface-dwelling stock that colonized the Micos cave and also introgressed into the ancient Pachón cave population. The appearance of albinism in captive Micos cavefish, caused by the same loss-of-function allele present in Pachón cavefish, implies that geographically and phylogenetically distinct cave populations can evolve the same troglomorphic phenotype from standing genetic variation present in the ancestral taxon.     

Modification of Proteinase Inhibitor II in Adzuki Beans during Germination

We investigated the effects of compounds isolated from a methanolic extract of rose hips on melanin biosynthesis in B16 mouse melanoma cells and the possible mechanisms responsible for the inhibition of melanin biosynthesis. We found that, among the isolated compounds, quercetin was a particularly potent melanogenesis inhibitor. To reveal the mechanism for this inhibition, the effects on tyrosinase of B16 mouse melanoma were measured. Quercetin decreased the intracellular tyrosinase activity as well as the tyrosinase activity in a cell culture-free system. We also examined the cellular level of tyrosinase protein and found that quercetin dose-dependently inhibited tyrosinase protein expression. We consider from these results that the inhibition of melanogenesis by quercetin was due to the inhibition of both tyrosinase activity and of the protein expression.     

A New Method for Estimation of the Mycelial Weight in Koji

A New method was devised for the estimation of the mycelial weight in rice-koji. In this method, the content of glucosamine in koji was used for the calculation of mycelial weight. The content of glucosamine in the mycelia of Aspergillus oryzae, koji, and rice was determined by a colorimetry after hydrolysis of these materials with sulfuric acid and purification of glucosamine fraction with a Dowex 50 W column. And the values of glucosamine were 114.5 mg/g in mycelia, 3.03 in the koji for amazake,* 1.34 in the koji for sake, and 0.0 in rice. The mycelial contents calculated from these data were 2.6% dry weight in amazake-koji and 1.2% in sake-koji.     

Molecular Weight Determination of Component Polypeptides of Glutenin after Fractionation by Gel Filtration

Reduced and cyanoethylated glutenin was fractionated into three fractions (F I, F II and F III) by gel filtration on Sephadex G–100 in 0.1 m acetic acid. The molecular weight determination was made with these three fractions by sedimentation equilibrium in 6.5 m guanidine hydrochloride containing 0.01 m acetic acid. The molecular weight obtained was 44,000 for F II, and 32,000 for F III. F I showed a distribution of molecular weight due to the aggregation. The average molecular weight of F I was 52,000, being 27,000 at the meniscus and 98,000 at the bottom. The estimation of molecular weight by SDS–PAGE* gave overestimated values for glutenin polypeptides, as was already reported for gliadin.