Parkinson's Disease, Parkinsonisms, and Mitochondria: the Role of Nuclear and Mitochondrial DNA.

PURPOSE OF REVIEW: Overwhelming evidence indicates that mitochondrial dysfunction is a central factor in Parkinson's disease (PD) pathophysiology. This paper aims to review the latest literature published, focusing on genetic defects and expression alterations affecting mitochondria-associated genes, in support of their key role in PD pathogenesis. RECENT FINDINGS: Thanks to the use of new omics approaches, a growing number of studies are discovering alterations affecting genes with mitochondrial functions in patients with PD and parkinsonisms. These genetic alterations include pathogenic single-nucleotide variants, polymorphisms acting as risk factors, and transcriptome modifications, affecting both nuclear and mitochondrial genes. We will focus on alterations of mitochondria-associated genes described by studies conducted on patients or on animal/cellular models of PD or parkinsonisms. We will comment how these findings can be taken into consideration for improving the diagnostic procedures or for deepening our knowledge on the role of mitochondrial dysfunctions in PD.

One year of surgical mask testing at the University of Bologna labs: Lessons learned from data analysis.

The outbreak of SARS-CoV-2 pandemic highlighted the worldwide lack of surgical masks and personal protective equipment, which represent the main defense available against respiratory diseases as COVID-19. At the time, masks shortage was dramatic in Italy, the first European country seriously hit by the pandemic: aiming to address the emergency and to support the Italian industrial reconversion to the production of surgical masks, a multidisciplinary team of the University of Bologna organized a laboratory to test surgical masks according to European regulations. The group, driven by the expertise of chemical engineers, microbiologists, and occupational physicians, set-up the test lines to perform all the functional tests required. The laboratory started its activity on late March 2020, and as of the end of December of the same year 435 surgical mask prototypes were tested, with only 42 masks compliant to the European standard. From the analysis of the materials used, as well as of the production methods, it was found that a compliant surgical mask is most likely composed of three layers, a central meltblown filtration layer and two external spunbond comfort layers. An increase in the material thickness (grammage), or in the number of layers, does not improve the filtration efficiency, but leads to poor breathability, indicating that filtration depends not only on pure size exclusion, but other mechanisms are taking place (driven by electrostatic charge). The study critically reviewed the European standard procedures, identifying the weak aspects; among the others, the control of aerosol droplet size during the bacterial filtration test results to be crucial, since it can change the classification of a mask when its performance lies near to the limiting values of 95 or 98%.

R106C TFG variant causes infantile neuroaxonal dystrophy "plus" syndrome.

TFG (tropomyosin-receptor kinase fused gene) encodes an essential protein in the regulation of vesicular trafficking between endoplasmic reticulum and Golgi apparatus. The homozygous variant c.316C > T within TFG has been previously associated with a complicated hereditary spastic paraplegia (HSP) phenotype in two unrelated Indian families. Here, we describe the first Italian family with two affected siblings harboring the same variant, who in childhood were classified as infantile neuroaxonal dystrophy (INAD) based on clinical and neuropathological findings. Twenty years after the first diagnosis, exome sequencing was instrumental to identify the genetic cause of this disorder and clinical follow-up of patients allowed us to reconstruct the natural history of this clinical entity. Investigations on patient's fibroblasts demonstrate the presence of altered mitochondrial network and inner membrane potential, associated with metabolic impairment. Our study highlights phenotypic heterogeneity characterizing individuals carrying the same pathogenic variant in TFG and provides an insight on tight connection linking mitochondrial efficiency and neuronal health to vesicular trafficking.

ADCK3 mutations with epilepsy, stroke-like episodes and ataxia: a POLG mimic?

BACKGROUND AND PURPOSE: Defects of coenzyme Q10 (CoQ10) metabolism cause a variety of disorders ranging from isolated myopathy to multisystem involvement. ADCK3 is one of several genes associated with CoQ10 deficiency that presents with progressive cerebellar ataxia, epilepsy, migraine and psychiatric disorders. Diagnosis is challenging due to the wide clinical spectrum and overlap with other mitochondrial disorders. METHODS: A detailed description of three new patients and one previously reported patient from three Norwegian families with novel and known ADCK3 mutations is provided focusing on the epileptic semiology and response to treatment. Mutations were identified by whole exome sequencing and in two measurement of skeletal muscle CoQ10 was performed. RESULTS: All four patients presented with childhood-onset epilepsy and progressive cerebellar ataxia. Three patients had epilepsia partialis continua and stroke-like episodes affecting the posterior brain. Electroencephalography showed focal epileptic activity in the occipital and temporal lobes. Genetic investigation revealed ADCK3 mutations in all patients including a novel change in exon 15: c.T1732G, p.F578V. There was no apparent genotype-phenotype correlation. CONCLUSION: ADCK3 mutations can cause a combination of progressive ataxia and acute epileptic encephalopathy with stroke-like episodes. The clinical, radiological and electrophysiological features of this disorder mimic the phenotype of polymerase gamma (POLG) related encephalopathy and it is therefore suggested that ADCK3 mutations be considered in the differential diagnosis of mitochondrial encephalopathy with POLG-like features.

A novel environmental chamber for neuronal network multisite recordings.

Environmental stability is a critical issue for neuronal networks in vitro. Hence, the ability to control the physical and chemical environment of cell cultures during electrophysiological measurements is an important requirement in the experimental design. In this work, we describe the development and the experimental verification of a closed chamber for multisite electrophysiology and optical monitoring. The chamber provides stable temperature, pH and humidity and guarantees cell viability comparable to standard incubators. Besides, it integrates the electronics for long-term neuronal activity recording. The system is portable and adaptable for multiple network housings, which allows performing parallel experiments in the same environment. Our results show that this device can be a solution for long-term electrophysiology, for dual network experiments and for coupled optical and electrical measurements.

Transition from unclassified Ktedonobacterales to Actinobacteria during amorphous silica precipitation in a quartzite cave environment.

The orthoquartzite Imawarì Yeuta cave hosts exceptional silica speleothems and represents a unique model system to study the geomicrobiology associated to silica amorphization processes under aphotic and stable physical-chemical conditions. In this study, three consecutive evolution steps in the formation of a peculiar blackish coralloid silica speleothem were studied using a combination of morphological, mineralogical/elemental and microbiological analyses. Microbial communities were characterized using Illumina sequencing of 16S rRNA gene and clone library analysis of carbon monoxide dehydrogenase (coxL) and hydrogenase (hypD) genes involved in atmospheric trace gases utilization. The first stage of the silica amorphization process was dominated by members of a still undescribed microbial lineage belonging to the Ktedonobacterales order, probably involved in the pioneering colonization of quartzitic environments. Actinobacteria of the Pseudonocardiaceae and Acidothermaceae families dominated the intermediate amorphous silica speleothem and the final coralloid silica speleothem, respectively. The atmospheric trace gases oxidizers mostly corresponded to the main bacterial taxa present in each speleothem stage. These results provide novel understanding of the microbial community structure accompanying amorphization processes and of coxL and hypD gene expression possibly driving atmospheric trace gases metabolism in dark oligotrophic caves.

Loss of apoptosis-inducing factor critically affects MIA40 function.

Mitochondrial apoptosis-inducing factor (AIF) influences the oxidative phosphorylation (OXPHOS) system and can be recruited as a mediator of cell death. Pathogenic mutations in the AIFM1 gene cause severe human diseases. Clinical manifestations include inherited peripheral neuropathies, prenatal cerebral abnormalities and progressive mitochondrial encephalomyopathies. In humans, rodents and invertebrates, AIF deficiency results in loss of respiratory complexes and, therefore, impaired OXPHOS. The molecular mechanisms underlying AIF-induced mitochondrial dysfunction remain elusive. Here we show that AIF physically interacts with the oxidoreductase CHCHD4/MIA40. In patient-derived fibroblasts as well as in tissues and glia cells from Harlequin (Hq) mutant mice, AIF deficiency correlates with decreased MIA40 protein levels, without affecting mRNA transcription. Importantly, MIA40 overexpression counteracts loss of respiratory subunits in Hq cells. Together, our findings suggest that MIA40 reduction contributes to the effects of AIF deficiency on OXPHOS, as it may impact on the correct assembly and maintenance of the respiratory subunits. This may be relevant for the development of new therapeutic approaches for AIF-related mitochondrial disorders.

Apparent lack of a dopaminergic-cholinergic link in the rat nucleus accumbens septi-tuberculum olfactorium.

The nucleus accumbens septi and tuberculum olfactorium (NAS-TO), which from part of the mesolimbic dopaminergic system, and the striatum, which is part of the nigrostriatal dopamingeric system, contain high levels of both dopamine (DA) and acetylcholine and resemble each other in some other biochemical properties. We determined whether blockade or stimulation of DA receptors by agonists or antagonists affects the cholinergic neurons in this brain structure. The DA receptor antagonists haloperidol, pimozide, chlorpromazine and clozapine had no effect on the acetylcholine level in the NAS-TO even at 2-8 times the minimum dose required to maximally decrease striatal acetylcholine. Similarly, D-amphetamine and bromocriptine (CB 154), DA receptor stimulating drugs, had no effect on the acetylcholine level in this brain area at doses up to 3 times higher than those that produced a maximum increase in the striatum. Piribedil (15-120 mg/kg) and apomorphine (4 mg/kg) did increase acetylcholine in the NAS-TO but the action was not blocked by pimozide and is therefore not attributable to DA receptor action. The data thus indicate an apparent lack of a dopaminergic-cholinergic link in the NAS-TO.

Cholinergic-dopaminergic interaction in the striatum: the effect of 6-hydroxydopamine or pimozide treatment on the increased striatal acetylcholine levels induced by apomorphine, piribedil and d-amphetamine.

Apomorphine (1 and 2 mg/kg), piribedil (15 and 60 mg/kg) and d-amphetamine (5 and 10 mg/kg) increased rat striatal acetylcholine levels without affecting choline. Pretreatment with pimozide (0.5 mg/kg) completely antagonized the effect of apomorphine and piribedil and by itself markedly decreased striatal acetylcholine levels. d-Amphetamine signigicantly antagonized the effect of pimozide. Nine days after pretreatment with 6-hydroxydopamine plus pargyline, striatal dopamine was decreased by 78% while acetylcholine and choline levels remained unaltered. Under these conditions, the effect of d-amphetamine was completely abolished while apomorphine and piribedil were just as active as in the vehicle-treated group. The results suggest that d-amphetamine acted indirectly to increase striatal acetylcholine levels probably through the release of dopamine and/or noradrenaline, while apomorphine and piribedil acted directly at dopamine receptor sites.

Organic semiconductors for artificial vision.

Organic semiconductors have emerged in the past two decades as promising materials for many technological applications. Thanks to their unique optoelectronic properties, they represent an ideal system to mimic natural photoreceptor functioning. This similarity has been exploited, on one hand, to realize organic-based devices for image detection, taking advantage of typical features of natural visual systems, such as trichromatic sensing; on the other hand, these materials can be interfaced with biological tissues for cell photo-stimulation, with the main goal of restoring light sensitivity in the case of retinas affected by photoreceptor degeneration.

Large-scale, high-resolution electrophysiological imaging of field potentials in brain slices with microelectronic multielectrode arrays.

Multielectrode arrays (MEAs) are extensively used for electrophysiological studies on brain slices, but the spatial resolution and field of recording of conventional arrays are limited by the low number of electrodes available. Here, we present a large-scale array recording simultaneously from 4096 electrodes used to study propagating spontaneous and evoked network activity in acute murine cortico-hippocampal brain slices at unprecedented spatial and temporal resolution. We demonstrate that multiple chemically induced epileptiform episodes in the mouse cortex and hippocampus can be classified according to their spatio-temporal dynamics. Additionally, the large-scale and high-density features of our recording system enable the topological localization and quantification of the effects of antiepileptic drugs in local neuronal microcircuits, based on the distinct field potential propagation patterns. This novel high-resolution approach paves the way to detailed electrophysiological studies in brain circuits spanning spatial scales from single neurons up to the entire slice network.

Development and validation of a spike detection and classification algorithm aimed at implementation on hardware devices.

Neurons cultured in vitro on MicroElectrode Array (MEA) devices connect to each other, forming a network. To study electrophysiological activity and long term plasticity effects, long period recording and spike sorter methods are needed. Therefore, on-line and real time analysis, optimization of memory use and data transmission rate improvement become necessary. We developed an algorithm for amplitude-threshold spikes detection, whose performances were verified with (a) statistical analysis on both simulated and real signal and (b) Big O Notation. Moreover, we developed a PCA-hierarchical classifier, evaluated on simulated and real signal. Finally we proposed a spike detection hardware design on FPGA, whose feasibility was verified in terms of CLBs number, memory occupation and temporal requirements; once realized, it will be able to execute on-line detection and real time waveform analysis, reducing data storage problems.

POLG1 in idiopathic Parkinson disease.

We studied POLG1 in 140 UK patients with idiopathic Parkinson disease (PD) and 279 Italian patients with PD and compared them to a UK control group (n = 207) and an Italian control group (n = 285). Our observations do not support a role for common POLG1 genetic variants in PD and indicate that dominant POLG1 mutations are a rare cause of parkinsonism in the general population.