Single-Molecule Imaging of Recycling Synaptic Vesicles in Live Neurons

The capacity of neurons to communicate and store information in the brain critically depends on neurotransmission, a process which relies on the release of chemicals called neurotransmitters stored in synaptic vesicles at the presynaptic nerve terminals. Following their fusion with the presynaptic plasma membrane, synaptic vesicles are rapidly reformed via compensatory endocytosis. The investigation of the endocytic pathway dynamics is severely restricted by the diffraction limit of light and, therefore, the recycling of synaptic vesicles, which are roughly 45 nm in diameter, has been primarily studied with electrophysiology, low-resolution fluorescence-based techniques, and electron microscopy. Here, we describe a recently developed technique we named subdiffractional tracking of internalized molecules (sdTIM) that can be used to track and study the mobility of recycling synaptic vesicles in live hippocampal presynapses. The chapter provides detailed guidelines on the application of the sdTIM protocol and highlights controls, adaptations, and limitations of the technique

Expansion microscopy: principles and uses in biological research

Many biological investigations require 3D imaging of cells or tissues with nanoscale spatial resolution. We recently discovered that preserved biological specimens can be physically expanded in an isotropic fashion through a chemical process. Expansion microscopy (ExM) allows nanoscale imaging of biological specimens with conventional microscopes, decrowds biomolecules in support of signal amplification and multiplexed readout chemistries, and makes specimens transparent. We review the principles of how ExM works, advances in the technology made by our group and others, and its applications throughout biology and medicine.NIH (Grants 1R01NS102727, 1R01EB024261, 1R41MH112318, 1R01MH110932, 1RM1HG008525, 1DP1NS087724)NSF (Grant 1734870)IARPA (Grant D16PC00008)US Army Research Laboratory & US Army Research Office (Contract W911NF1510548)US–Israel Binational Science Foundation (Grant 2014509

Termites and soil properties

[Extract] This chapter reviews the advances made in our knowledge of the effects of termites on the physical, chemical and biological properties of soils. Emphasis has been placed on more recent contributions, particularly those that explore new concepts in the ecology of termites and soils. There are sections dealing with the effects of termite activity on soil profile development, soil physical properties, soil chemical properties, soil microbiology and plant growth. The physical effects of termites on soils range from micromorphological to soil profile evolution and structure. Recent evidence points to the substantial positive influence of termites on soil hydraulic conductivity and infiltration rates. Their influence on organic matter decomposition and nutrient recycling rates are well recognized and in some landscapes termite mounds act as foci for nutrient redistribution. New information on the microbiology of termite mounds suggests that most sites of diverse bacterial and fungal activity. Furthermore, the association between mound-building termites and the microbial population present in the structures has a synergistic effect on organic matter decomposition and hence nutrient cycling and availability. Examination of the effects of termite activity on plant production generally indicates a positive influence