PubMed Health⌕ Search

PubMed · 11732191

Primary and secondary plasmodesmata: structure, origin, and functioning.

Abstract

In the multicellular organisms of higher plants, plasmodesmata provide pathways for intimate symplasmic communication between neighboring cells. The arguments summarized in the present review demonstrate that plasmodesmata are diverse and highly dynamic structures. Differences in the plasmodesmal origin and modifications of the plasmodesmal structure and functioning at the various cell interfaces are the basic means which give rise to a complicated and flexibile symplasmic network. This complex communication system is discussed to serve a significant role in the coordinated development and in the concerted physiological functioning of the cells within the plant tissues, organs, and organisms.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

K Ehlers, R Kollmann. 2001. Primary and secondary plasmodesmata: structure, origin, and functioning.. https://doi.org/10.1007/bf02680127

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

Differential cell signaling testing for cell-cell communication inference from single-cell data by dominoSignal.

MOTIVATION: Algorithms for ligand-receptor network inference have emerged as commonly used tools to estimate cell-cell communication from reference single-cell data. Many studies employ these algorithms to compare signaling between conditions and lack methods to statistically identify signals that are significantly different. We previously developed the cell communication inference algorithm Domino, which considers ligand and receptor gene expression in association with downstream transcription factor activity scoring. We developed the dominoSignal software to innovate upon Domino and extend its functionality to test statistically differential cellular signaling. RESULTS: This new functionality includes the compilation of active signals as linkages from multiple subjects in a single-cell data set and testing condition-dependent signaling linkage. The software is applicable for analysis of single-cell data sets with multiple subjects as biological replicates as well as with bootstrapped replicates from data sets with few or pooled subjects. We use simulation studies to benchmark the number of subjects in compared groups and cells within an annotated cell type sufficient to accurately identify differential linkages. We demonstrate the application of the Differential Cell Signaling Test (DCST) in the dominoSignal software to investigate consequences of cancer cell phenotypes and immunotherapy on cell-cell communication in tumor microenvironments. These applications in cancer studies demonstrate the ability of differential cell signaling analysis to infer changes to cell communication networks from therapeutic or experimental perturbations, which is broadly applicable across biological systems. AVAILABILITY: dominoSignal is available through Bioconductor at https://www.bioconductor.org/packages/release/bioc/html/dominoSignal.html.

Cell Communication↗

Involvement of connexin 43 in human trophoblast cell fusion and differentiation.

The syncytiotrophoblast is the principal component of the human placenta involved in feto-maternal exchanges and hormone secretion. The syncytiotrophoblast arises from the fusion of villous cytotrophoblasts. We recently showed that functional gap junctional intercellular communication (GJIC) is an important prerequisite for syncytiotrophoblast formation and that connexin 43 (Cx43) is present in cytotrophoblasts and in the syncytiotrophoblast. To determine whether Cx43 is directly involved in trophoblast fusion, we used an antisense strategy in primary cultures of human villous cytotrophoblasts that spontaneously differentiate into the syncytiotrophoblast by cell fusion. We assessed the morphological and functional differentiation of trophoblasts by desmoplakin immunostaining, by quantifying hCG (human chorionic gonadotropin) production and by measuring the expression of specific trophoblast genes (hCG and HERV-W). Furthermore, we used the gap-FRAP (fluorescence recovery after photobleaching) method to investigate functional GJIC. Cytotrophoblasts treated with Cx43 antisense aggregated and fused poorly. Furthermore, less HERV-W env mRNA, hCGbeta mRNA and hCG secretion were detected in Cx43 antisense-treated cytotrophoblasts than in cells treated with scrambled antisense. Treatment with Cx43 antisense dramatically reduced the percentage of coupled trophoblast cells. Taken together, these results suggest that Cx43 is directly involved in human trophoblast cell-cell communication, fusion and differentiation.

Cell Communication↗

Dendritic cells support sequential reprogramming of chemoattractant receptor profiles during naive to effector T cell differentiation.

T cells undergo chemokine receptor switches during activation and differentiation in secondary lymphoid tissues. Here we present evidence that dendritic cells can induce changes in T cell expression of chemokine receptors in two continuous steps. In the first switch over a 4-5 day period, dendritic cells up-regulate T cell expression of CXCR3 and CXCR5. Additional stimulation leads to the second switch: down-regulation of lymphoid tissue homing related CCR7 and CXCR5, and up-regulation of Th1/2 effector tissue-targeting chemoattractant receptors such as CCR4, CCR5, CXCR6, and CRTH2. We show that IL-4 and IL-12 can determine the fate of the secondary chemokine receptor switch. IL-4 enhances the generation of CCR4(+) and CRTH2(+) T cells, and suppresses the generation of CXCR3(+) T cells and CCR7(-) T cells, while IL-12 suppresses the level of CCR4 in responding T cells. Furthermore, IL-4 has positive effects on generation of CXCR5(+) and CCR7(+) T cells during the second switch. Our study suggests that the sequential switches in chemokine receptor expression occur during naive T cell interaction with dendritic cells. The first switch of T cell chemokine receptor expression is consistent with the fact that activated T cells migrate within lymphoid tissues for interaction with B and dendritic cells, while the second switch predicts the trafficking behavior of effector T cells away from lymphoid tissues to effector tissue sites.

Cell Communication↗