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As a vital parameter in living cells and tissues, the micro-environment is crucial for the living organisms. Significantly, organelles require proper micro-environment to achieve normal physiological processes, and the micro-environment in organelles can reflect the state of organelles in living cells. Moreover, some abnormal micro-environments in organelles are closely related to organelle dysfunction and disease development. So, visualizing and monitoring the variation of micro-environments in organelles is helpful for physiologists and pathologists to study the mechanisms of the relative diseases. Recently, a large variety of fluorescent probes was developed to study the micro-environments in living cells and tissues. However, the systematic and comprehensive reviews on the organelle micro-environment in living cells and tissues have rarely been published, which may hinder the research progress in the field of organic fluorescent probes. In this review, we will summarize the organic fluorescent probes for monitoring the microenvironment, such as viscosity, pH values, polarity, and temperature. Further, diverse organelles (mitochondria, lysosome, endoplasmic reticulum, cell membrane) about microenvironments will be displayed. In this process, the fluorescent probes about the “off-on” and ratiometric category (the diverse fluorescence emission) will be discussed. Moreover, the molecular designing, chemical synthesis, fluorescent mechanism, and the bio-applications of these organic fluorescent probes in cells and tissues will also be discussed. Significantly, the merits and defects of current microenvironment-sensitive probes are outlined and discussed, and the development tendency and challenges for this kind of probe are presented. In brief, this review mainly summarizes some typical examples and highlights the progress of organic fluorescent probes for monitoring micro-environments in living cells and tissues in recent research. We anticipate that this review will deepen the understanding of microenvironment in cells and tissues and facilitate the studies and development of physiology and pathology.

No abstract

The formation of propagules (conidia and ascospores) is the critical stage for the transmission of the pathogenic fungus Stemphylium eturmiunum. However, how the development of these propagules is regulated remains to be fully understood. Here, we show that nitric oxide (NO) is necessary for the formation of conidia and pseudothecia in S. eturmiunum. Application of NO scavenger carboxy-CPTIO (cPTIO) or soluble guanylate cyclase (sGC) inhibitor NS2028 abolishes the formation of conidia and pseudothecia. In the culture of S. eturmiunum, supplement of NO-releasing compound sodium nitroprusside (SNP) results in an increased formation of conidia at 0.2 mmol/L, and pseudothecia at 2 mmol/L. SNP supplement also triggered increased biosynthesis of melanin, which can be inhibited partially upon the addition of either arbutin or tricyclazole, the specific inhibitors for 3,4-dihydroxyphenylalanine (DOPA) and dihydroxynaphthalene (DHN) synthetic pathway, respectively. Intriguingly, enhanced melanin biosynthesis triggered an increased formation of propagules; while its inhibition impaired their formation. The SNP-induced increment in the formation of propagules can be also compromised upon supplement of cPTIO or NS-2028. RT-PCR analysis showed that SNP at 0.2 mmol/L promoted transcription of the genes encoding the conidiation co-regulators brlA, abA, and wetA, and inhibited at 2 mmol/L. In contrast, application of SNP at 2 mmol/L increased transcription of the genes encoding mat1, and mat2, the genes related to sexual reproduction, and the transcription of two DNH melanin synthetic genes pks1 and pks2, and the key gene tyr for DOPA melanin biosynthesis. However, the increased transcription of these genes is down-regulated or blocked upon supplement of cPTIO or NS-2028. Thus, NO regulates asexual and sexual development, as well as melanin synthesis in S. eturmiunum possibly through NO-sGC-GMP signaling pathway.