Cellular & Molecular Imaging

Sample videos acquired with the InVision device. Videos are of schistosome miracidia swimming in a custom arena and can be used to develop and optimize tracking pipelines.

Vertebrate organs undergo massive expansion during post-embryonic growth, yet how this process is organized across entire organs at single-cell resolution remains unclear. This has been limited by the inability to resolve individual cells throughout intact adult organs at sufficient resolution and with cell-type specificity. Here we establish whole adult-organ expansion microscopy (WAO-ExM), enabling in toto single-cell-resolved visualization of every hepatocyte within a complete adult vertebrate liver. Using transgenic reporters to label hepatocyte nuclei, we readily capture 1,265,206 cells within an intact adult liver spanning ~5 mm in thickness and quantify their expansion dynamics across the entire post-embryonic growth period. We reveal a non-linear growth regime in which hepatocyte number increases by 538-fold, driven by a temporally concentrated burst that is not reflected by overall body growth. Lineage tracing integrated with WAO-ExM determines that this expansion is not even, with a few hepatocytes undergoing drastic clonal expansion at the whole-organ scale. Perturbation of extracellular matrix laminins further decouples liver shaping process from total cell number increase, demonstrating independent regulatory control of tissue architecture and cell proliferation. This framework extends to diseased livers and other adult organs, including the heart and pancreas. Altogether, these findings define the cell-level dynamics underlying centimeter-scale organ-level growth, and we demonstrate a generalizable platform for adult vertebrate organ to be fully resolved at bona fide single-cell resolution.

This dataset includes microscopy and sequence data related to the study and used in the figures. It includes light and electron microscopy images. The sample preparation, image acquisition and analysis protocols are described in the methods.

The neglected tropical disease schistosomiasis impacts over 700 million people globally. Schistosoma mansoni, the trematode parasite that causes the most common type of schistosomiasis, requires planorbid pond snails of the genus Biomphalaria to support its larval development and transformation to the cercarial form that can infect humans. A greater understanding of neural signaling systems that are specific to the Biomphalaria intermediate host could lead to novel strategies for parasite or snail control. This study examined a Biomphalaria glabrata neural channel that is gated by the neuropeptide FMRF-NH2. The Biomphalaria glabrata FMRF-NH2 gated sodium channel (Bgl-FaNaC) amino acid sequence was highly conserved with FaNaCs found in related gastropods, especially the planorbid Planorbella trivolvis (91% sequence identity). In common with the P. trivolvis FaNaC, the B. glabrata channel exhibited a low affinity (EC50: 3 x 10-4 M) and high specificity for the FMRF-NH2 agonist. Its expression in the central nervous system, detected with immunohistochemistry and in situ hybridization, was widespread, with the protein localized mainly to neuronal fibers and the mRNA confined to cell bodies. Colocalization of the Bgl-FaNaC message with its FMRF-NH2 agonist precursor occurred in some neurons associated with male mating behavior. At the mRNA level, Bgl-FaNaC expression was decreased at 20 and 35 days post infection (dpi) by S. mansoni. Increased expression of the transcript encoding the FMRF-NH2 agonist at 35 dpi was proposed to reflect a compensatory response to decreased receptor levels. Altered FMRF-NH2 signaling could be vital for parasite proliferation in its intermediate host and may therefore present innovative opportunities for snail control.

Sample videos acquired with the InVision device. Videos are of schistosome miracidia swimming in a custom arena and can be used to develop and optimize tracking pipelines.

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Synaptojanin 1 is a brain enriched phosphoinositide phosphatase implicated in endocytosis at the synapse. A mutation (R258Q) that selectively impairs its Sac1 phosphatase domain causes early onset familial Parkinsonism. Neurons of mice with this mutation display synaptic vesicle traffic defects across the brain, but selective dystrophic changes in a subset of dopaminergic axons in the dorsolateral striatum. Using correlative light microscopy-FIB-SEM of mutant mouse striata to visualize in 3D these abnormal structures we show that they represent clusters of focal axonal dilations harboring massive, onion-like DAT enriched plasma membrane infoldings, generally localized next to cell bodies of neighboring cells, often engulfing evaginations of such cells. This dysmorphia was associated with a deficit in dopamine release in the same striatal region. Given the involvement of Synj1 in endocytic mechanisms, these structures may reflect an imbalance between exocytosis and endocytosis. Their occurrence only in a subset of axons suggest a vulnerability threshold of these axons beyond which the expansion of the plasma membrane is not counteracted by compensatory mechanisms.

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