The close association between membranes and organelles, and the intense chloroplast remodeling in parenchyma cells of extrafloral nectaries occurred only at the secretion time and suggest a relationship with the nectar secretion. Associations between membranes and organelles have been well documented in different tissues and cells of plants, but poorly explored in secretory cells. Here, we described the close physical juxtaposition between membranes and organelles, mainly with chloroplasts, in parenchyma cells of Citharexylum myrianthum (Verbenaeceae) extrafloral nectaries under transmission electron microscopy, using conventional and microwave fixation. At the time of nectar secretion, nectary parenchyma cells exhibit a multitude of different organelle and membrane associations as mitochondria-mitochondria, mitochondria-endoplasmic reticulum, mitochondria-chloroplast, chloroplast-nuclear envelope, mitochondria-nuclear envelope, chloroplast-plasmalemma, chloroplast-chloroplast, chloroplast-tonoplast, chloroplast-peroxisome, and mitochondria-peroxisome. These associations were visualized as amorphous electron-dense material, a network of dense fibrillar material and/or dense bridges. Chloroplasts exhibited protrusions variable in shape and extension, which bring them closer to each other and to plasmalemma, tonoplast, and nuclear envelope. Parenchyma cells in the pre- and post-secretory stages did not exhibit any association or juxtaposition of membranes and organelles, and chloroplast protrusions were absent. Chloroplasts had peripheral reticulum that was more developed in the secretory stage. We propose that such subcellular phenomena during the time of nectar secretion optimize the movement of signaling molecules and the exchange of metabolites. Our results open new avenues on the potential mechanisms of organelle contact in parenchyma nectary cells, and reveal new attributes of the secretory cells on the subcellular level.
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http://dx.doi.org/10.1007/s00425-018-2844-7 | DOI Listing |
Int J Mol Sci
December 2024
Biochemistry, Molecular Biology B and Immunology Department, University of Murcia (UMU), 30120 Murcia, Spain.
Glioblastoma (GB) is one of the most aggressive and treatment-resistant cancers due to its complex tumor microenvironment (TME). We previously showed that GB progression is dependent on the aberrant induction of chaperone-mediated autophagy (CMA) in pericytes (PCs), which promotes TME immunosuppression through the PC secretome. The secretion of extracellular matrix (ECM) proteins with anti-tumor (Lumican) and pro-tumoral (Osteopontin, OPN) properties was shown to be dependent on the regulation of GB-induced CMA in PCs.
View Article and Find Full Text PDFMolecules
January 2025
Laboratory of Neurochemistry and Cellular Biology, Institute of Health Sciences, Federal University of Bahia, Av. Reitor Miguel Calmon S/N, Salvador 40231-300, BA, Brazil.
Glioblastomas (GBM) are malignant tumours with poor prognosis. Treatment involves chemotherapy and/or radiotherapy; however, there is currently no standard treatment for recurrence, and prognosis remains unfavourable. Inflammatory mediators and microRNAs (miRNAs) influence the aggressiveness of GBM, being involved in the communication with the cells of the tumour parenchyma, including microglia/macrophages, and maintaining an immunosuppressive microenvironment.
View Article and Find Full Text PDFGastro Hep Adv
August 2024
Department of Surgery, University of Miami Miller School of Medicine, Miami, Florida.
The development of hepatic metastases is the leading cause of mortality in gastrointestinal (GI) cancers and substantial research efforts have been focused on elucidating the intricate mechanisms by which tumor cells successfully migrate to, invade, and ultimately colonize the liver parenchyma. Recent evidence has shown that perturbations in myeloid biology occur early in cancer development, characterized by the initial expansion of specific innate immune populations that promote tumor growth and facilitate metastases. This review summarizes the pathophysiology underlying the proliferation of myeloid cells that occurs with incipient neoplasia and explores the role of innate immune-host interactions, specifically granulocytes and neutrophil extracellular traps, in promoting hepatic colonization by tumor cells through the formation of the "premetastatic niche".
View Article and Find Full Text PDFBackground: Autoimmune pancreatitis (AIP) is a form of chronic pancreatitis that presents clinically with obstructive icterus, histologically with infiltration of pancreatic parenchyma by inflammatory cells leading to chronic inflammation with fibrosis, and therapeutically with good response to corticosteroid therapy. Clinically, it may resemble malignant disease, making diagnosis difficult and requiring a multidisciplinary team (gastroenterologist, endoscopist, radiologist, surgeon, pathologist). Two types of AIP are distinguished.
View Article and Find Full Text PDFVaccines (Basel)
November 2024
Department of Systems Biotechnology, Chung-Ang University, Anseong 17456, Republic of Korea.
Respiratory syncytial virus (RSV) causes symptoms similar to a mild cold for adults, but in case of infants, it causes bronchitis and/or pneumonia, and in some cases, mortality. Mucosal immunity within the respiratory tract includes tissue-resident memory T (T) cells and tissue-resident memory B (B) cells, which provides rapid and efficient protection against RSV re-infection. Therefore, vaccine strategies should aim to generate mucosal immune responses.
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