in-vivo-two-photon-microscopy-of-single-nerve-endings-in-skin

<em>In Vivo</em> Two-Photon Microscopy of Single Nerve Endings in Skin

Nerve endings in skin are involved in physiological processes such as sensing1 as well as in pathological processes such as neuropathic pain2. Their ...

acute-brain-trauma-in-mice-followed-by-longitudinal-two-photon-imaging

Acute Brain Trauma in Mice Followed By Longitudinal Two-photon Imaging

Although acute brain trauma often results from head damage in different accidents and affects a substantial fraction of the population, there is no ...

flat-floored-air-lifted-platform-new-method-for-combining-behavior

Flat-floored Air-lifted Platform: A New Method for Combining Behavior with Microscopy or Electrophysiology on Awake Freely Moving Rodents

It is widely acknowledged that the use of general anesthetics can undermine the relevance of electrophysiological or microscopical data obtained from a ...

University of Helsinki

At most, many protein-misfolding diseases develop as environmentally induced sporadic disorders. Recent studies indicate that the dynamic interplay between a wide repertoire of noncoding RNAs and the environment play an important role in brain development and pathogenesis of brain disorders. To elucidate this new issue, novel animal models which reproduce the most prominent disease manifestations are required. For this, transgenic Drosophila strains were constructed to express small highly structured, non-coding RNA under control of a heat shock promoter. Expression of the RNA induced formation of intracellular aggregates revealed by Thioflafin T in embryonic cell culture and Congo Red in the brain of transgenic flies. Also, this strongly perturbed the brain control of locomotion monitored by the parameters of sound production and memory retention of young 5-day-old males. This novel model demonstrates that expression of non-coding RNA alone is sufficient to trigger neuropathology.

Non-coding RNA as a trigger of neuropathologic disorder phenotypes in transgenic Drosophila.

Peripheral astrocytic processes (PAPs) are highly motile structures that are strategically positioned in close proximity to synapses. Long-lasting PAP retraction in hypothalamus is known to alter synaptic transmission. The PAP motility is likely to be actin-based because they are known to contain actin-related proteins such as Ezrin. However, the link between dynamic activity-dependent changes in astrocytic morphology and the synaptic function has not been established experimentally, presumably due to lack of appropriate tools. To selectively suppress activity-dependent morphological plasticity of astrocytes, we developed a bicistronic construct that allows simultaneous tracing and manipulating the morphology of PAPs. The construct is designed for co-expression of (i) the mutant actin binding protein Profilin-1 (abdProf-1) with a single amino acid substitution (H119E) that prevents its binding to actin monomers with (ii) the membrane-targeted morphological tracer LckGFP. Cultured cortical astrocytes transfected with this construct showed abdProf-1 overexpression at a 5-fold level compared to the endogenous Profilin-1. The cells also expressed LckGFP at a level sufficient for precise morphological tracing. We found that photolysis of caged Ca²⁺ induced a pronounced outgrowth of PAPs, which was suppressed by abdProf-1 overexpression in terms of PAP number, growth rate and maximal length. In contrast, the morphological complexity of astrocytes, basal motility of their PAPs and major cytoskeletal structures were not affected by abdProf-1 overexpression. In summary, we identified the actin binding by Profilin-1 as a pivotal mechanism in activity-dependent morphological plasticity of PAPs in cultured astrocytes.

Dmitry Molotkov

Neuroscience Center

University of Helsinki

In Vivo Two-Photon Microscopy of Single Nerve Endings in Skin

Acute Brain Trauma in Mice Followed By Longitudinal Two-photon Imaging

Flat-floored Air-lifted Platform: A New Method for Combining Behavior with Microscopy or Electrophysiology on Awake Freely Moving Rodents