Phase transition or phase separation occurs in cells and tissues in many physiological events, such as protein granules (P granules) in early C. elegans development. Inappropriate phase transition is often associated with pathologic processes such as RNA-protein complex (RNP) and FUS-mutation-associated diseases. Given its ubiquity, phase transition has been considered a new frontier for comprehending physiological processes and pathological diseases. However, molecular and cellular mechanisms of phase transition in situ remain poorly described. Combining histochemistry with polarization analysis and biochemical thin-layer chromatography, we identified a massive phase transition change during the development of Taihe fowl (Gallus gallus domesticus Brisson). During embryonic day 12 (E12), the livers of these Silkie chicken demonstrated a sudden massive transition from hepatic lipid droplets (HLD) into hepatic liquid crystal droplets (HLCDs). We identified these changes by characterizing the sudden appearance of birefringent Maltese crosses (MCs) typical to liquid crystals (LC) where non-birefringent lipid droplets used to reside within hepatic cells. LC status was confirmed by fluidity with shape-changing and in vitro thermal phase transition tests. These HLCDs were present consistently until the early postnatal days after hatching. Using thin-layer chromatography combined with X-ray diffraction analysis, we determined that these HLCDs were composed of cholesterol, cholesterol ester and lecithin, which are the same as the components of cytoplasmic membrane. There was no change in the quantity of lipid components during liver development to suggest a critical mass of components triggering these changes. However, expressions of membrane-associated autophagy markers LC3A and Beclin 1 increased dramatically during this HLD to HLCD transition. Increases in membrane-associated LC3A and Beclin 1 are localized with massive increases in membrane lipid components of HLCDs. Areas with enhanced LC3A and Beclin 1 signaling have been associated with liquid crystal MCs to the thickness of 69 Å (Bragg d value). These associations indicate the possible regulatory role autophagy plays during liquid crystal phase transition in embryonic liver development. Reactivation of this autophagy pathway may be a possible mechanism behind the development of non-alcoholic fatty liver disease in adulthood.

Calcium induced calcium release signaling (CICR) plays a critical role in many biological processes. Every cellular activity from cell proliferation and apoptosis, development and ageing, to neuronal synaptic plasticity and regeneration have been associated with Ryanodine receptors (RyRs). Despite the importance of calcium signaling, the exact mechanism of its function in early development is unclear. As an organism with a short gestational period, the embryos of Drosophila melanogaster are prime study subjects for investigating the distribution and localization of CICR associated proteins and their regulators during development. However, because of their lipid-rich embryos and chitin-rich chorion, their utility is limited by the difficulty of mounting embryos on glass surfaces. In this work, we introduce a practical protocol that significantly enhances the attachment of Drosophila embryo onto slides and detail methods for successful histochemistry, immunohistochemistry, and insitu hybridization. The chrome alum gelatin slide-coating method and embryo preembedding method dramatically increases the yield in studying Drosophila embryo protein and RNA expression. To demonstrate this approach, we studied DmFKBP12/ Calstabin, a well-known regulator of RyR during early embryonic development of Drosophila melanogaster. We identified DmFKBP12 in as early as the syncytial blastoderm stage and report the dynamic expression pattern of DmFKBP12 during development: initially as an evenly distributed protein in the syncytial blastoderm, then preliminarily localizing to the basement layer of the cortex during cellular blastoderm, before distributing in the primitive neuronal and digestion architecture during the threegem layer phase in early gastrulation. This distribution may explain the critical role RyR plays in the vital organ systems that originate in from these layers: the suboesophageal and supraesophageal ganglion, ventral nervous system, and musculoskeletal system.

Abstract Background In the past 30 years, incidences of non-alcoholic fatty liver disease (NAFLD) has risen by 30%. However, there is still no clear mechanism or accurate method of anticipating liver failure. Here we reveal the phase transitions of liquid crystalline qualities in hepatic lipid droplets (HLDs) as a novel method of anticipating prognosis. Methods NAFLD was induced by feeding C57BL/6J mice on a high-fat (HiF) diet. These NAFLD livers were then evaluated under polarized microscopy, X-ray diffraction and small-angle scattering, lipid component chromatography analysis and protein expression analysis. Optically active HLDs from mouse model and patient samples were both then confirmed to have liquid crystal characteristics. Liver MAP1LC3A expression was then evaluated to determine the role of autophagy in liquid crystal HLD (LC-HLD) formation. Results Unlike the normal diet cohort, HiF diet mice developed NAFLD livers containing HLDs exhibiting Maltese cross birefringence, phase transition, and fluidity signature to liquid crystals. These LC-HLDs transitioned to anisotropic crystal at 0 °C and remain crystalline. Temperature increase to 42 °C causes both liquid crystal and crystal HLDs to convert to isotropic droplet form. These isotropic HLDs successfully transition to anisotropic LC with fast temperature decrease and anisotropic crystal with slow temperature decrease. These findings were duplicated in patient liver. Patient LC-HLDs with no inner optical activity were discovered, hinting at lipid saturation as the mechanism through which HLD acquire LC characteristics. Downregulation of MAP1LC3A in conjunction with increased LC-HLD also implicated autophagy in NAFLD LC-HLD formation. Conclusions Increasing concentrations of amphiphilic lipids in HLDs favors organization into alternating hydrophilic and hydrophobic layers, which present as LC-HLDs. Thus, evaluating the extent of liquid crystallization with phase transition in HLDs of NAFLD patients may reveal disease severity and predict impending liver damage.

心脏心肌细胞和神经系统神经元细胞是人类及哺乳动物中最为重要的两类兴奋细胞,心脏心肌细胞为整个机体血液循环提供动力,将氧气和营养物质通过血液运输送至各组织,同时,将二氧化碳等有害气体和代谢废物带离各组织器官;而神经系统神经元细胞则为有机体生存的指挥体系,为生物的生存进化提供了可能.两类兴奋细胞均以RyRs、IP3R家族为主导,以及它们的重要调节蛋白DCK来协调,并借助钙诱导的钙释放CICR体系完成上述功能.DCK通过结合到CaV1.1和Ca1.2上,从而间接调节RyR的功能.DCK-CaV系统调节RyRs和IP3Rs两个蛋白家族介导钙离子从内质网/肌浆网释放进入胞浆,进而在心肌细胞肌肉收缩、突触神经冲动的传递、激素分泌、基因转录、蛋白折叠、程序性凋亡等以细胞功能为基础的生理过程中发挥非常重要的作用,DCK的突变及异常均会引起包括人类在内的相关疾病.DCK的基因调控作用会直接影响心脏传导系统,通过RyRs和IP3R以及这两个基因的构象改变,导致心律失常,比如儿茶酚胺能多态性心室心搏过速,乃至心脏突然死亡.同时,DCK基因的表达对神经元热感觉感知的调控也起到了重要作用,通过PKC联合调控SFO神经元血管紧张素II介导的钙瞬变来控制大脑相关功能的正常发挥.如果异常,则会导致大脑病理生理学的病变.

近20年以来病毒源性已经是第二次对人类发起致命的侵染攻击,已造成两次严重危害全球人类生命的重大疫情.考量如何研发最为有效的保护人类和限制和消灭新冠病毒的方案,是目前亟待解决的重要问题,目前新冠病毒席卷全球,现在也是细胞生物学和病毒分子生物学等基础科学应用于疫情病理研究的关键时刻.本文就新冠病毒有效侵染粘液上皮细胞和心血管的分子机理进行了介绍,对该病毒RNA基因组在细胞内的整合、复制和释放扩散过程进行了探讨.对新冠病毒通过血液再次感染内皮细胞而导致包括心肺肾关联心血管疾病深度感染的分析表明,感染使人体内启动的炎症风暴使得免疫系统对外部侵染的特异性抵御功能丧失,而变成对包括自身正常细胞在内的无差别免疫攻击.本文分析揭示了ACE2-S蛋白可能导致的血钙和细胞钙相关蛋白在靶向细胞和组织过程中发生改变的可能细胞分子作用机理,为尽快从细胞分子机理上认清和战胜新冠病毒,以致为未来能将危害人类生命健康的病毒源性侵染消灭于萌芽状态提供了有价值的信息.