Melanin Biosynthesis Inhibitors from Tarragon Artemisia dracunculus

The EtOH extract of tarragon Artemisia dracunculus, a perennial herb in the family Asteraceae, was found to potently inhibit α-melanocyte-stimulating hormone (α-MSH) induced melanin production in B16 mouse melanoma cells. Bioassay-guided fractionation led to the isolation of two alkamide compounds, isobutyl (1) and piperidiyl (2) amides of undeca-2E,4E-dien-8,10-dynoic acid. The respective EC₅₀ values for melanin biosynthesis inhibition were 1.8 and 2.3 μg/mL for 1 and 2.     

A New Process for the Production of Coenzyme A

A new process has been described for the preparation of coenzyme A of high purity from the cultured broth of Brevibacterium ammoniagenes IFO 12071. The product was obtained in a high yield by the use of Duolite S–30, charcoal, and Dowex 1×2, and identified chemically and enzymatically. This method is simple, rapid, and compact, requires no special equipment, and has been shown to be adaptable for preparing large amounts of highly pure coenzyme A.     

Cell Aggregation Factor Produced by Streptomyces sp. Strain No. A-3315

We searched for a new aggregation factor, and found one we named 3315-AF in the culture filtrate of Streptomyces sp. strain No. A-3315. 3315-AF was purified by active carbon treatment, ethanol precipitation, gel filtration on Sepharose 2B, ether extraction, silica gel chromatography and gel filtration on Sephadex LH-20. 3315-AF was found to be a triglyceride which consists of myristic acid, pentadecanoic acid, and palmitic acid. The aggregation activity of 3315-AF was maximum around pH 8.0 at 30°C and the activity increased by addition of metallic ions such as calcium and cobalt. Hyaluronic acid, ovalbumin, BSA, and casein inhibited the aggregation activity. 3315-AF aggregated Proteus vulgaris and HeLa cells as well as Serratia marcescens and weakly aggregated Saccharomyces cerevisiae, Candida albicans, C. neoformans, and Leukemia P388, but it was inert to human erythrocytes and Sarcoma 180.     

Optoacoustic mesoscopy analysis and quantitative estimation of specific imaging metrics in Fitzpatrick skin phototypes II to V

Raster Scanning Optoacoustic Mesoscopy (RSOM) is a novel optoacoustic imaging modality that offers non‐invasive, label‐free, high resolution (~7 μm axial, ~30 μm lateral) imaging up to 1 to 2 mm below the skin, providing novel quantitative insights into skin pathophysiology. As the RSOM image contrast mechanism is based on light absorption, it is expected that the amount of melanin present in the skin will affect RSOM images. However, the effect of skin tone in the performance of RSOM has not been addressed so far. Herein, we present the efficiency of RSOM for in vivo skin imaging of human subjects with Fitzpatrick (FP) skin types between II to V. RSOM images acquired from the volar forearms of the subjects were used to derive metrics used in RSOM studies, such as total blood volume, vessel diameter and melanin signal intensity. Our study shows that the melanin signal intensity derived from the RSOM images exhibited an excellent correlation with that obtained from a clinical colorimeter for the subjects of varying FP skin types. We could successfully estimate the vessel diameter at different depths of the dermis. Furthermore, our study shows that there is a need to compensate for total blood volume calculated for subjects with higher FP skin types due to the lower signal‐to‐noise ratio in dermis, owing to strong absorption of light by melanin. This study sheds light into how RSOM can be used for studying various skin conditions in populations with different skin phenotypes.     

纤维素酶-超声波协同提取黑木耳黑色素工艺及其抗氧化活性分析

黑色素是黑木耳的主要活性成分之一,在黑木耳的药理活性上发挥着重要作用。为了提高黑木耳黑色素的提取得率,实验采用正交法和响应面法对纤维素酶-超声波协同提取黑木耳黑色素的提取工艺进行了优化,并对最优条件下提取的黑木耳黑色素体外抗氧化活性进行了分析。实验结果表明,纤维素酶-超声波协同提取黑木耳黑色素的最优条件为:酶添加量12mg,酶解温度40℃,酶解pH 5.0,酶解时间120min,NaOH浓度1.27mol/L,料液比1:40,超声功率300W,超声时间52min,超声温度60℃。在最优条件下,黑木耳黑色素提取得率可达到10.48%,相比于实验设置的未添加纤维素酶的超声波组黑色素提取得率提高了12.93%。抗氧化结果表明,采用纤维素酶-超声波协同提取的黑色素相比于未加纤维素酶提取的黑色素清除ABTS、DPPH和羟基自由基的能力更强。研究结果为黑木耳黑色素的高效提取及其产品的应用开发奠定了基础。     

大鲵Agouti基因的克隆、表达及多态性分析

刺鼠信号蛋白(Agouti)是哺乳动物和鸟类黑色素合成过程中的重要调控因子,影响动物的体色(毛色)。为研究Agouti在两栖动物体色形成过程中的作用,本研究利用PCR技术扩增得到大鲵Andrias davidianus的Agouti基因部分cDNA序列并进行了相关的生物信息学分析,进一步使用实时荧光定量PCR检测了大鲵Agouti基因在皮肤、肝脏等10个组织和器官中的表达情况,并检测了4种不同体色大鲵皮肤组织中Agouti基因的表达量。同时采用直接测序法,比较了不同体色大鲵Agouti基因编码区的序列差异。结果显示,大鲵Agouti基因cDNA序列长1 068 bp,开放阅读框399 bp,编码132个氨基酸残基。蛋白质同源性分析表明,大鲵Agouti蛋白具有与其他物种一致的保守Agouti结构域,其蛋白质序列与两栖爬行类序列相似性较高,与哺乳动物和鸟类相似性较低。系统进化分析显示,大鲵Agouti基因与高山倭蛙Nanorana parkeri、美国短吻鳄Alligator mississippiensis、中华鳖Pelodiscus sinensis等物种的亲缘关系较近。实时荧光定量PCR分析表明,Agouti基因mRNA在大鲵不同组织中均有表达,皮肤中的表达量最高。在4种不同体色大鲵皮肤组织中,黄色皮肤中的Agouti基因表达量高于其他体色。不同体色大鲵Agouti基因编码区序列一致。大鲵Agouti基因独特的序列特征及其表达的组织特异性暗示了其在两栖动物体色形成过程中可能具有与其他物种不同的调控机制。这些结果为进一步研究Agouti在大鲵体色形成过程中的作用提供了基础资料。     

Ommochromes in invertebrates: biochemistry and cell biology

Ommochromes are widely occurring coloured molecules of invertebrates, arising from tryptophan catabolism through the so‐called Tryptophan → Ommochrome pathway. They are mainly known to mediate compound eye vision, as well as reversible and irreversible colour patterning. Ommochromes might also be involved in cell homeostasis by detoxifying free tryptophan and buffering oxidative stress. These biological functions are directly linked to their unique chromophore, the phenoxazine/phenothiazine system. The most recent reviews on ommochrome biochemistry were published more than 30 years ago, since when new results on the enzymes of the ommochrome pathway, on ommochrome photochemistry as well as on their antiradical capacities have been obtained. Ommochromasomes are the organelles where ommochromes are synthesised and stored. Hence, they play an important role in mediating ommochrome functions. Ommochromasomes are part of the lysosome‐related organelles (LROs) family, which includes other pigmented organelles such as vertebrate melanosomes. Ommochromasomes are unique because they are the only LRO for which a recycling process during reversible colour change has been described. Herein, we provide an update on ommochrome biochemistry, photoreactivity and antiradical capacities to explain their diversity and behaviour both in vivo and in vitro. We also highlight new biochemical techniques, such as quantum chemistry, metabolomics and crystallography, which could lead to major advances in their chemical and functional characterisation. We then focus on ommochromasome structure and formation by drawing parallels with the well‐characterised melanosomes of vertebrates. The biochemical, genetic, cellular and microscopic tools that have been applied to melanosomes should provide important information on the ommochromasome life cycle. We propose LRO‐based models for ommochromasome biogenesis and recycling that could be tested in the future. Using the context of insect compound eyes, we finally emphasise the importance of an integrated approach in understanding the biological functions of ommochromes.     

The taphonomy of colour in fossil insects and feathers

Colouration is an important multifunctional attribute of modern animals, but its evolutionary history is poorly resolved, in part because of our limited ability to recognize and interpret fossil evidence of colour. Recent studies on structural and pigmentary colours in fossil insects and feathers have illuminated important aspects of the anatomy, taphonomy, evolution and function of colour in these fossils. An understanding of the taphonomic factors that control the preservation of colour is key to assessing the fidelity with which original colours are preserved and can constrain interpretations of the visual appearance of fossil insects and theropods. Various analytical approaches can identify anatomical and chemical evidence of colour in fossils; experimental taphonomic studies inform on how colour alters during diagenesis. Preservation of colour is controlled by a suite of factors, the most important of which relate to the diagenetic history of the host sediment, that is, maximum burial temperatures and fluid flow, and subsurface weathering. Future studies focussing on key morphological and chemical aspects of colour preservation relating to cuticular pigments in insects and keratinous structures and nonmelanin pigments in feathers, for example, will resolve outstanding questions regarding the taphonomy of colour and will enhance our ability to infer original colouration and its functions in fossil insects and theropods.