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1.
Biology (Basel) ; 10(2)2021 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-33669470

RESUMO

Several green algae can divide by multiple fission and spontaneously synchronize their cell cycle with the available light regime. The yields that can be obtained from a microalgal culture are directly affected by cell cycle events. Chromochloris zofingiensis is considered as one of the most promising microalgae for biotechnological applications due to its fast growth and the flexible trophic capabilities. It is intensively investigated in the context of bio-commodities production (carotenoids, storage lipids); however, the pattern of cell-cycle events under common cultivation strategies was not yet characterized for C. zofingiensis. In this study, we have employed fluorescence microscopy to characterize the basic cell-cycle dynamics under batch and continuous modes of phototrophic C. zofingiensis cultivation. Staining with SYBR green-applied in DMSO solution-enabled, for the first time, the clear and simple visualization of polynuclear stages in this microalga. Accordingly, we concluded that C. zofingiensis divides by a consecutive pattern of multiple fission, whereby it spontaneously synchronizes growth and cell division according to the available illumination regime. In high-light continuous culture or low-light batch culture, C. zofingiensis cell-cycle was completed within several light-dark (L/D) cycles (14 h/10 h); however, cell divisions were synchronized with the dark periods only in the high-light continuous culture. In both modes of cultivation, daughter cell release was mainly facilitated by division of 8 and 16-polynuclear cells. The results of this study are of both fundamental and applied science significance and are also important for the development of an efficient nuclear transformation system for C. zofingiensis.

2.
Immunity ; 38(3): 581-95, 2013 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-23395676

RESUMO

CD103+ dendritic cells (DCs) carry bacteria from the small intestine and can present antigens to T cells. Yet they have not been recorded sampling luminal bacteria or presenting bacterial antigens in mesentery lymph nodes. We used 2-photon microscopy in live Cx3cr1(+/gfp) ×Cd11c-YFP mice to study these processes. At steady state, sparse CD103+ DCs occupied the epithelium. They patrolled among enterocytes while extending dendrites toward the lumen, likely using tight-junction proteins to penetrate the epithelium. Challenge with Salmonella triggered chemokine- and toll-like receptor (TLR)-dependent recruitment of additional DCs from the lamina propria (LP). The DCs efficiently phagocytosed the bacteria using intraepithelial dendrites. Noninvasive bacteria were similarly sampled. In contrast, CD103+ DCs sampled soluble luminal antigen inefficiently. In mice harboring CD103+ DCs, antigen-specific CD8 T cells were subsequently activated in MLNs. Intestinal CD103+ DCs are therefore equipped with unique mechanisms to independently complete the processes of uptake, transportation, and presentation of bacterial antigens.


Assuntos
Apresentação de Antígeno/imunologia , Antígenos de Bactérias/imunologia , Antígenos CD/imunologia , Células Dendríticas/imunologia , Cadeias alfa de Integrinas/imunologia , Mucosa Intestinal/imunologia , Animais , Antígenos CD/metabolismo , Antígeno CD11c/genética , Antígeno CD11c/imunologia , Antígeno CD11c/metabolismo , Linfócitos T CD8-Positivos/imunologia , Linfócitos T CD8-Positivos/metabolismo , Receptor 1 de Quimiocina CX3C , Linhagem Celular Tumoral , Movimento Celular/imunologia , Células Cultivadas , Células Dendríticas/metabolismo , Citometria de Fluxo , Interações Hospedeiro-Patógeno/imunologia , Cadeias alfa de Integrinas/metabolismo , Mucosa Intestinal/metabolismo , Mucosa Intestinal/microbiologia , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Ativação Linfocitária/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microscopia de Fluorescência por Excitação Multifotônica , Mucosa/imunologia , Mucosa/metabolismo , Mucosa/microbiologia , Receptores de Quimiocinas/genética , Receptores de Quimiocinas/imunologia , Receptores de Quimiocinas/metabolismo , Salmonella typhi/imunologia , Salmonella typhi/fisiologia , Salmonella typhimurium/imunologia , Salmonella typhimurium/fisiologia , Receptores Toll-Like/imunologia , Receptores Toll-Like/metabolismo
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