Robust neural integration from retinal transplants in mice deficient in GFAP and vimentin

Background: Learning and memory is basic aspects in neurogenetics as most of the neurological disorders start with dementia or memory loss. Several genes associated with memory formation have been discovered. MicroRNA genes miR-1000 and miR-375 were reported to be associated with neural integration and glucose homeostasis in some insects and vertebrates. However, neuronal function of these genes is yet to be established in D. melanogaster. Objective: Possible role of miR-1000 and miR-375 in learning and memory formation in this fly has been explored in the present study. Methods: Both appetitive and aversive olfactory conditional learning were tested in the miR-1000 and miR-375 knockout (KO) strains and compared with wild one. Five days old third instar larvae were trained by allowing them to be associated with an odor with reward (fructose) or punishment (salt). Then, the larvae were tested to calculate their preferences to the odor trained with. Learning index (LI) values and larval locomotion speed were calculated for all strains. Results: No significant difference was observed for larval locomotion speed in mutant strains. Knockout strain of miR-1000 showed significant deficiency in both appetitive and aversive memory formation whereas miR-375 KO strain showed a significantly lower response only in appetitive one. Conclusion: The results of the present study indicate important role played by these two genes in forming short-term memory in D. melanogaster.

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A cross-species neural integration of gravity for motor optimization

Science Advances ◽

10.1126/sciadv.abf7800 ◽

2021 ◽

Vol 7 (15) ◽

pp. eabf7800

Author(s):

Jeremie Gaveau ◽

Sidney Grospretre ◽

Bastien Berret ◽

Dora E. Angelaki ◽

Charalambos Papaxanthis

Keyword(s):

Optimization Strategy ◽

Motor Patterns ◽

Activation Patterns ◽

Single Degree Of Freedom ◽

Single Degree ◽

Neural Integration ◽

Gravity Effects ◽

Neural Signature ◽

Experimental Findings ◽

Muscular Activation

Recent kinematic results, combined with model simulations, have provided support for the hypothesis that the human brain shapes motor patterns that use gravity effects to minimize muscle effort. Because many different muscular activation patterns can give rise to the same trajectory, here, we specifically investigate gravity-related movement properties by analyzing muscular activation patterns during single-degree-of-freedom arm movements in various directions. Using a well-known decomposition method of tonic and phasic electromyographic activities, we demonstrate that phasic electromyograms (EMGs) present systematic negative phases. This negativity reveals the optimal motor plan’s neural signature, where the motor system harvests the mechanical effects of gravity to accelerate downward and decelerate upward movements, thereby saving muscle effort. We compare experimental findings in humans to monkeys, generalizing the Effort-optimization strategy across species.

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Heterogeneity and neurovascular integration of intraportally transplanted islets revealed by 3-D mouse liver histology

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00605.2020 ◽

2021 ◽

Author(s):

Chien-Chia Chen ◽

Shih-Jung Peng ◽

Pei-Yu Wu ◽

Hung-Jen Chien ◽

Chih-Yuan Lee ◽

...

Keyword(s):

Islet Transplantation ◽

Mouse Liver ◽

Image Data ◽

Liver Histology ◽

Systematic Assessment ◽

3 Dimensional ◽

Neural Integration ◽

Quantitative Analyses ◽

Graft Tissue

Background: Intraportal islet transplantation has been clinically applied for treatment of unstable type 1 diabetes. However, in the liver, systematic assessment of the dispersed islet grafts and the graft-hepatic integration remains difficult, even in animal models. This is due to the lack of global and in-depth analyses of the transplanted islets and their microenvironment. Here, we apply 3-dimensional (3-D) mouse liver histology to investigate the islet graft microstructure, vasculature, and innervation. Methods: Streptozotocin-induced diabetic mice were used in syngeneic intraportal islet transplantation to achieve euglycemia. Optically cleared livers were prepared to enable 3-D morphological and quantitative analyses of the engrafted islets. Results: 3-D image data reveal the clot- and plaque-like islet grafts in the liver: the former are derived from islet emboli and associated with ischemia, whereas the latter (minority) resemble the plaques on the walls of portal vessels (e.g., at the bifurcation) with mild, if any, peri-graft tissue damage. Three weeks after transplantation, both types of grafts are revascularized, yet significantly more lymphatics are associated with the plaque- than clot-like grafts. Regarding the islet reinnervation, both types of grafts connect to the peri-portal nerve plexus and develop peri- and intra-graft innervation. Specifically, the sympathetic axons and varicosities contact the α-cells, highlighting the graft-host neural integration. Conclusion/interpretation: We present the heterogeneity of the intraportally transplanted islets and the graft-host neurovascular integration in mice. Our work provides the technical and morphological foundation for future high-definitional 3-D tissue and cellular analyses of human islet grafts in the liver.

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