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41.
L L Mak 《Developmental biology》1978,65(2):435-446
The fusion of neural folds to form the neural tube is a process in which presumptive contacting surfaces become adhering. An ultrastructural examination of regions of neural folds in the neurulae of three amphibian species (Hyla regilla, Rana pipiens, and Xenopus laevis), using both transmission and scanning electron microscopy, revealed that, prior to fusion, there is formation of vesicles within cells lining the neural groove, development of extracellular vesicles, changes in the surface morphology of the cells forming the fusion area, and extension of projections (filopodia) from cells lining the neural groove. The association of intra- and extracellular vesicles and filopodia with cells of the neural groove and folds suggests that these organelles may be involved in preparing the neural folds for initial contact, adhesion, and fusion. Ultrastructural differences in reaction of neural fold cell surfaces to staining by ruthenium red, colloidal iron, Alcian blue-lanthanum nitrate, and concanavalin A-hemocyanin indicate that the glycosaminoglycan compositions of these cell surfaces differ from those of presumptive epidermal cells. 相似文献
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Helena Santos-Rosa Gonzalo Millán-Zambrano Namshik Han Tommaso Leonardi Marie Klimontova Simona Nasiscionyte Luca Pandolfini Kostantinos Tzelepis Till Bartke Tony Kouzarides 《Molecular cell》2021,81(13):2793-2807.e8
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Luana Lionetto Martina Ulivieri Matilde Capi Donatella De Bernardini Francesco Fazio Andrea Petrucca Leda Marina Pomes Ottavia De Luca Giovanna Gentile Barbara Casolla Martina Curto Gerardo Salerno Serena Schillizzi Maria Simona Torre Iolanda Santino Monica Rocco Paolo Marchetti Antonio Aceti Marina Borro 《生物化学与生物物理学报:疾病的分子基础》2021,1867(3):166042
Immune dysregulation is a hallmark of patients infected by SARS-CoV2 and the balance between immune reactivity and tolerance is a key determinant of all stages of infection, including the excessive inflammatory state causing the acute respiratory distress syndrome. The kynurenine pathway (KP) of tryptophan (Trp) metabolism is activated by pro-inflammatory cytokines and drives mechanisms of immune tolerance. We examined the state of activation of the KP by measuring the Kyn:Trp ratio in the serum of healthy subjects (n = 239), and SARS-CoV2-negative (n = 305) and -positive patients (n = 89). Patients were recruited at the Emergency Room of St. Andrea Hospital (Rome, Italy). Kyn and Trp serum levels were assessed by HPLC/MS-MS. Compared to healthy controls, both SARS-CoV2-negative and -positive patients showed an increase in the Kyn:Trp ratio. The increase was larger in SARS-CoV2-positive patients, with a significant difference between SARS-CoV2-positive and -negative patients. In addition, the increase was more prominent in males, and positively correlated with age and severity of SARS-CoV2 infection, categorized as follows: 1 = no need for intensive care unit (ICU); 2 ≤ 3 weeks spent in ICU; 3 ≥ 3 weeks spent in ICU; and 4 = death. The highest Kyn:Trp values were found in SARS-CoV2-positive patients with severe lymphopenia. These findings suggest that the Kyn:Trp ratio reflects the level of inflammation associated with SARS-CoV2 infection, and, therefore, might represent a valuable biomarker for therapeutic intervention. 相似文献
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Alice Toso Simona Schifano Charlotte Oxborough Krista McGrath Luke Spindler Anabela Castro Lucy Evangelista Vanessa Filipe Maria José Gonçalves Antonio Marques Inês Mendes da Silva Raquel Santos Maria João Valente Iona McCleery Michelle Alexander 《American journal of physical anthropology》2021,176(2):208-222
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TMEM41B and VMP1 are scramblases and regulate the distribution of cholesterol and phosphatidylserine
Yang Emma Li Yichang Wang Ximing Du Tizhong Zhang Hoi Yin Mak Sarah E. Hancock Holly McEwen Elvis Pandzic Renee M. Whan Yvette Celine Aw Ivan E. Lukmantara Yiqiong Yuan Xiuju Dong Anthony Don Nigel Turner Shiqian Qi Hongyuan Yang 《The Journal of cell biology》2021,220(6)
TMEM41B and VMP1 are integral membrane proteins of the endoplasmic reticulum (ER) and regulate the formation of autophagosomes, lipid droplets (LDs), and lipoproteins. Recently, TMEM41B was identified as a crucial host factor for infection by all coronaviruses and flaviviruses. The molecular function of TMEM41B and VMP1, which belong to a large evolutionarily conserved family, remains elusive. Here, we show that TMEM41B and VMP1 are phospholipid scramblases whose deficiency impairs the normal cellular distribution of cholesterol and phosphatidylserine. Their mechanism of action on LD formation is likely to be different from that of seipin. Their role in maintaining cellular phosphatidylserine and cholesterol homeostasis may partially explain their requirement for viral infection. Our results suggest that the proper sorting and distribution of cellular lipids are essential for organelle biogenesis and viral infection. 相似文献
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Pedro Barbosa Liudmila Zhaunova Simona Debilio Verdiana Steccanella Van Kelly Tony Ly Hiroyuki Ohkura 《The Journal of cell biology》2021,220(2)
Meiosis creates genetic diversity by recombination and segregation of chromosomes. The synaptonemal complex assembles during meiotic prophase I and assists faithful exchanges between homologous chromosomes, but how its assembly/disassembly is regulated remains to be understood. Here, we report how two major posttranslational modifications, phosphorylation and ubiquitination, cooperate to promote synaptonemal complex assembly. We found that the ubiquitin ligase complex SCF is important for assembly and maintenance of the synaptonemal complex in Drosophila female meiosis. This function of SCF is mediated by two substrate-recognizing F-box proteins, Slmb/βTrcp and Fbxo42. SCF-Fbxo42 down-regulates the phosphatase subunit PP2A-B56, which is important for synaptonemal complex assembly and maintenance. 相似文献
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