Biology of the Cell最新文献

Understanding the spatiotemporal organization of components within living systems requires the highest resolution possible. Microscopy approaches that allow for a resolution below 250 nm include electron and super-resolution microscopy (SRM). The latter combines advanced imaging techniques and the optimization of image processing methods. Over the last two decades, various SRM-related approaches have been introduced, especially those relying on single molecule localization microscopy (SMLM). To develop and apply SMLM approaches, mitochondria are an ideal cellular compartment due to their size, which is below the standard diffraction limit. Furthermore, mitochondria are a dynamic yet narrow compartment, and a resolution below 250 nm is required to study their composition and multifaceted functions. To this end, several SMLM technologies have been used to reveal mitochondrial composition. However, there is still room for improvement in existing techniques to study protein–protein interactions and protein dynamics within this compartment. This review aims to offer an updated overview of the existing SMLM techniques and probes associated with mitochondria to enhance their resolution at the nanoscale. Last, it paves the way for future SMLM improvements to better resolve mitochondrial dynamics and functions.

The advancement of and prospects for stem cell research raise a number of specific ethical issues. While navigating the ethical landscape of stem cell research is often challenging for biology researchers and biotechnology innovators, it is also difficult for the public and other persons of concern (from ethicists to policy-makers) to grasp the technicalities of a burgeoning field that develops in many directions. Organoids are one of these new biotechnological constructs that are currently eliciting a rich debate in bioethics. In this guide, we argue that different types of organoids have different emerging properties with different ethical implications. Going from general properties to particular ones, we propose a typology of organoid technology and other associated biotechnology from a philosophical and ethical perspective. We point to relevant ethical issues and try to convey the sense of uncertainty peculiar to ongoing research and emerging technological objects.

One widespread technique to assess in relative terms the amount of broken DNA present in the genome of individual cells consists of immobilizing the cell's nucleus under an agarose pad (called the nucleoid) and subjecting the whole genome to electrophoresis to force broken DNA molecules out of it. Since the migrating broken DNA molecules create a tail behind the nucleoid, this technique is named the comet assay. While performing comet assays regularly, we systematically observed circular regions devoid of DNA within the nucleoid region. We characterize here that these correspond to clusters of neutral (apolar) lipids, since they could be labeled with neutral lipid-dying molecules, increased when cells were fed with oleic acid, and were irresponsive to the electrophoretic field. Of relevance, de-lipidation assays, either in vivo, or in vitro using acetone, show that these neutral lipids (NL) within the nucleoid limit the ability of broken DNA molecules to migrate into the comet tail. From a technical point of view, we show that de-lipidation permits a wider range for the detection of broken DNA molecules. Biologically, we put forward the notion that NL in contact with DNA may locally exert regulatory functions within the cell's nucleus.

Actinobacteria belonging to Mycobacterium and Rhodococcus genera are able to synthesize and intracellularly accumulate variable amounts of triacylglycerols (TAG) in the form of lipid droplets (LDs). The lipid storage capacity of LDs in cells is controlled by the balance between lipogenesis and lipolysis. The growth of LDs in bacterial cells may be directly promoted by TAG biosynthesis, whereas TAG degradation might result in the reduction of LD sizes and lipid storage capacity. Therefore, LD formation and turnover have to be precisely regulated to maintain a balanced lipid distribution, coupling gene regulation with the metabolic state of the cell. In eukaryotic cells, LDs have emerged as critical mediators of diverse cellular responses, including fatty acid trafficking and modulation of transcriptional programs. Recent studies performed in mycobacteria and rhodococci suggested the existence of similar crosstalk mechanisms between lipid metabolism, LDs, and gene expression regulation in cells. This review connects and organizes results of different studies in a comprehensive framework for providing evidence of “lipid metabolism-LDs-genomic DNA” crosstalk occurring in TAG-accumulating actinobacteria. We provide examples indicating that bacterial cells evolved sensing mechanisms that detect lipid metabolites changes as indicators of metabolic states, and adapt their transcriptional profiles through epigenetic-like mechanisms mediated by LD-associated proteins. Here, we describe the molecular interconnections of this coupling system and the main role of each component that integrates the information about the cellular metabolic state into the regulation of lipogenesis, LD formation and transcription in oleaginous bacteria.

Phosphoinositides also called Polyphosphoinositides (PPIns) are small lipid messengers with established key roles in organelle trafficking and cell signaling in response to physiological and environmental inputs. Besides their well-described functions in the cytoplasm, accumulating evidences pointed to PPIns involvement in transcription and chromatin regulation. Through the description of previous and recent advances of PPIns implication in transcription, this review highlights key discoveries on how PPIns modulate nuclear factors activity and might impact chromatin to modify gene expression. Finally, we discuss how PPIns nuclear and cytosolic metabolisms work jointly in orchestrating key transduction cascades that end in the nucleus to modulate gene expression.