Selection and study of a Candida molischiana mutant derepressed for β-glucosidase production

Abstract A mutant strain of Candida molischiana was selected. Analysis of the exocellular activity of Candida molischiana 35M5N grown on different carbon sources revealed that the biosynthesis of β-glucosidase is derepressed in this yeast strain. The strain is not a hyper-producer mutant. There were no observed differences in the endocellular and parietal activities of the wild and mutant strains. However, the mutant strain produced 35-fold more enzyme than the wild-type in the culture medium with glucose as carbon source. When glucose was used as carbon source, the mutant strain produced 90% more exocellular enzyme than when cellobiose was used as the carbon source.     

Neuroendocrinology and neurobiology of sebaceous glands

The nervous system communicates with peripheral tissues through nerve fibres and the systemic release of hypothalamic and pituitary neurohormones. Communication between the nervous system and the largest human organ, skin, has traditionally received little attention. In particular, the neuro‐regulation of sebaceous glands (SGs), a major skin appendage, is rarely considered. Yet, it is clear that the SG is under stringent pituitary control, and forms a fascinating, clinically relevant peripheral target organ in which to study the neuroendocrine and neural regulation of epithelia. Sebum, the major secretory product of the SG, is composed of a complex mixture of lipids resulting from the holocrine secretion of specialised epithelial cells (sebocytes). It is indicative of a role of the neuroendocrine system in SG function that excess circulating levels of growth hormone, thyroxine or prolactin result in increased sebum production (seborrhoea). Conversely, growth hormone deficiency, hypothyroidism, and adrenal insufficiency result in reduced sebum production and dry skin. Furthermore, the androgen sensitivity of SGs appears to be under neuroendocrine control, as hypophysectomy (removal of the pituitary) renders SGs largely insensitive to stimulation by testosterone, which is crucial for maintaining SG homeostasis. However, several neurohormones, such as adrenocorticotropic hormone and α‐melanocyte‐stimulating hormone, can stimulate sebum production independently of either the testes or the adrenal glands, further underscoring the importance of neuroendocrine control in SG biology. Moreover, sebocytes synthesise several neurohormones and express their receptors, suggestive of the presence of neuro‐autocrine mechanisms of sebocyte modulation. Aside from the neuroendocrine system, it is conceivable that secretion of neuropeptides and neurotransmitters from cutaneous nerve endings may also act on sebocytes or their progenitors, given that the skin is richly innervated. However, to date, the neural controls of SG development and function remain poorly investigated and incompletely understood. Botulinum toxin‐mediated or facial paresis‐associated reduction of human sebum secretion suggests that cutaneous nerve‐derived substances modulate lipid and inflammatory cytokine synthesis by sebocytes, possibly implicating the nervous system in acne pathogenesis. Additionally, evidence suggests that cutaneous denervation in mice alters the expression of key regulators of SG homeostasis. In this review, we examine the current evidence regarding neuroendocrine and neurobiological regulation of human SG function in physiology and pathology. We further call attention to this line of research as an instructive model for probing and therapeutically manipulating the mechanistic links between the nervous system and mammalian skin.     

Minimal Erythema Dose (MED) Testing

Ultraviolet radiation (UV) therapy is sometimes used as a treatment for various common skin conditions, including psoriasis, acne, and eczema. The dosage of UV light is prescribed according to an individual''s skin sensitivity. Thus, to establish the proper dosage of UV light to administer to a patient, the patient is sometimes screened to determine a minimal erythema dose (MED), which is the amount of UV radiation that will produce minimal erythema (sunburn or redness caused by engorgement of capillaries) of an individual''s skin within a few hours following exposure. This article describes how to conduct minimal erythema dose (MED) testing. There is currently no easy way to determine an appropriate UV dose for clinical or research purposes without conducting formal MED testing, requiring observation hours after testing, or informal trial and error testing with the risks of under- or over-dosing. However, some alternative methods are discussed.     

青少年痤疮面部皮肤微生物群落结构变化

【背景】青少年痤疮是一种最常见的慢性炎症性损容性皮肤病,与痤疮丙酸杆菌的异常增殖有关。【目的】探究痤疮皮损区与附近无明显皮损区微生物组成与健康对照的差异,为从微生态角度防治痤疮提供理论基础。【方法】利用细菌16S rRNA基因V1-V2区和真菌TIS1高通量测序技术分析北京地区16岁青少年面部痤疮皮肤细菌和真菌群落结构,将痤疮皮损区与附近无明显皮损区微生物组成与健康组进行比较,寻找差异菌群。【结果】痤疮患者面部皮损区与附近无明显皮损区细菌多样性(Shannon指数)较健康对照组显著性降低(P0.001),主要与丙酸杆菌(痤疮丙酸杆菌)和葡萄球菌(表皮葡萄球菌PM221)显著性上升相关,而痤疮皮损区与附近未明显皮损区细菌组成无显著性差异。痤疮患者皮损区与附近无明显皮损区较健康对照组真菌丰富度(Chao1指数)显著性上升(P0.05),与限制性马拉色菌的显著上升相关。【结论】面部皮肤微生物变化与青少年痤疮的发生相关。本研究为从微生物角度防治痤疮提供理论依据。     

中药面膜联合红蓝光治疗寻常痤疮疗效观察

目的：观察中药面膜联合红蓝光治疗仪治疗寻常痤疮临床疗效及安全性。方法：66例寻常痤疮患者按就诊先后顺序随机分为3组：对照组、面膜组、联合组,治疗4周后进行疗效评估,治疗结束后4周随访复发情况。结果：联合组及面膜组疗效高于对照组（P〈0.05）。结论：中药面膜联合红蓝光治疗仪治疗寻常痤疮疗效好,不良反应少,优于单用疗法,痤疮后期维持治疗同样值得重视。     

宏基因组学技术在痤疮研究中的应用进展

高通量测序技术的发展提高了人们对微生物组的认识。宏基因组学技术因其全面和深入的分析功能被广泛应用于各种环境微生物组的研究中,尤其在阐明各种疾病与人体微生物组的关系中,宏基因组学技术具有重要作用。痤疮作为一种常见的皮肤疾病,严重影响人们皮肤美观度和心理健康。利用宏基因组学技术挖掘皮肤微生物与痤疮的关系,将有助于痤疮发病机理的研究和临床治疗方法的改进。通过介绍宏基因组学技术的发展背景、概述及其应用研究进展,探讨皮肤微生物与痤疮的关系,综述宏基因组学技术在痤疮研究中的应用现状,并总结目前宏基因组学技术在皮肤疾病研究中存在的问题,旨在为痤疮的宏基因组研究提供参考。     

THE MORPHOLOGY OF HYOLITHIDS AND ITS FUNCTIONAL IMPLICATIONS

Abstract:  The exceptionally preserved hyolithids Gompholites striatulus , Maxilites robustus , Maxilites snajdri and Maxilites sp. are described with particular emphasis on helen and muscle scar morphology. These two aspects of hyolithid morphology have remained controversial. In life position, each helen curved ventrally. When the operculum closed the aperture of the conch, each helen was locked at the commissure slit with its dorsal edge tilted forward. Inside the conch, it was held in the dorsal apertural plane and clear of the inner surface of the operculum. Previously unidentified muscle scars are described from both the operculum and the conch. Dorsal scars on the conch aperture held muscles directed to the operculum. Comparative study of the muscle insertion pattern indicates that hyolithids did not have serially arranged muscles and that all hyolithids may have had a common skeleto-muscular system. The arrangement of the muscle scars with respect to the helens suggests that the latter were capable of relatively complex movements and could have been used to propel the organism over the substrate. The general morphology and orientation of the helens suggests that in addition they functioned to stabilize the organism on the sea-floor.     

Assessment of forest recovery at Wu-Ling fire scars in Taiwan using multi-temporal Landsat imagery

Normalized Burn Ratio (NBR), a satellite-derived index widely used to map the burned area and to assess burn severity level, was reconceptualized to propose the indices of post-fire recovery condition and resilience. Time series Landsat imagery during 1994–2015 were used to observe the forest recovery of Wu-Ling fire scars in Taiwan. Burn Recovery Ratio (BRR) was newly developed as the indicator to better clarify the forest recovery status. Results show that BRR coupled with dNBR (bi-temporal NBR) could quantitatively describe the level of forest recovery through the heterogeneity of forest landscape which is confirmed by field investigation. Time of complete recovery (t_c), indicator of post-fire resilience, were predicted using curve-fitting of forest recovery trajectories to the exponential decay function. The spatial distribution of t_c could reveal the patterns of post-fire recovery across the fire scars. For wildfire prevention, the issue of fire recurrence should be concerned at the areas of fire-adapted species with low t_c value. For areas of deterioration sites with high t_c value, the rehabilitation project should be implemented to accelerate forest restoration.