Neuronal mitochondrial morphology abnormalities occur in models of familial amyotrophic lateral sclerosis (ALS) associated with SOD1 and TDP43 mutations. These abnormalities have been linked to mitochondrial axonal transport defects, but the temporal and spatial relationship between mitochondrial morphology and transport alterations in these two distinct genetic forms of ALS has not been investigated in vivo. To address this question, we crossed SOD1 (wild-type SOD1^WT and mutant SOD1^G93A) or TDP43 (mutant TDP43^A315T) transgenic mice with mice expressing the fluorescent protein Dendra targeted to mitochondria in neurons (mitoDendra). At different time points during the disease course, we studied mitochondrial transport in the intact sciatic nerve of living mice and analyzed axonal mitochondrial morphology at multiple sites, spanning from the spinal cord to the motor terminals. Defects of retrograde mitochondrial transport were detected at 45 days of age, before the onset of symptoms, in SOD1^G93A and TDP43^A315T mice, but not in SOD1^WT. At later disease stages, also anterograde mitochondrial transport was affected in both mutant mouse lines. In SOD1^G93A mice, mitochondrial morphological abnormalities were apparent at 15 days of age, thus preceding transport abnormalities. Conversely, in TDP43^A315T mice, morphological abnormalities appeared after the onset of transport defects. Taken together, these findings demonstrate that neuronal mitochondrial transport and morphology abnormalities occur in vivo and that they are common denominators of different genetic forms of the ALS. At the same time, differences in the temporal and spatial manifestation of mitochondrial abnormalities between the two mouse models of familial ALS imply that different molecular mechanisms may be involved.

Mitochondrial respiratory chain dysfunction, impaired intracellular Ca²⁺ homeostasis and activation of the mitochondrial apoptotic pathway are pathological hallmarks in animal and cellular models of familial amyotrophic lateral sclerosis associated with Cu/Zn‐superoxide dismutase mutations. Although intracellular Ca²⁺ homeostasis is thought to be intimately associated with mitochondrial functions, the temporal and causal correlation between mitochondrial Ca²⁺ uptake dysfunction and motor neuron death in familial amyotrophic lateral sclerosis remains to be established. We investigated mitochondrial Ca²⁺ handling in isolated brain, spinal cord and liver of mutant Cu/Zn‐superoxide dismutase transgenic mice at different disease stages. In G93A mutant transgenic mice, we found a significant decrease in mitochondrial Ca²⁺ loading capacity in brain and spinal cord, as compared with age‐matched controls, very early on in the course of the disease, long before the onset of motor weakness and massive neuronal death. Ca²⁺ loading capacity was not significantly changed in liver G93A mitochondria. We also confirmed Ca²⁺ capacity impairment in spinal cord mitochondria from a different line of mice expressing G85R mutant Cu/Zn‐superoxide dismutase. In excitable cells, such as motor neurons, mitochondria play an important role in handling rapid cytosolic Ca²⁺ transients. Thus, mitochondrial dysfunction and Ca²⁺‐mediated excitotoxicity are likely to be interconnected mechanisms that contribute to neuronal degeneration in familial amyotrophic lateral sclerosis.

An overview on the properties and applications of polymer and inorganic planar 1D photonic crystals fabricated from solution is provided here. In the last decades, photonic crystals became technologically relevant for light management, photovoltaics, sensing, and lasing. Such structures are traditionally produced by lithographic and vacuum techniques, but the need to reduce costs and to scale‐up the fabrication have lead the research toward new materials, simplified structures, and low‐cost mass scale growth processes. In this regard, polymer and inorganic mesoporous distributed Bragg reflectors fabricated from solution attracted considerable technological interest. This review focuses on the properties of such structures, concentrating on state‐of‐the‐art fabrication and applications.