Does Aneuploidy in the Brain Play a Role in Neurodegenerative Disease?

Aneuploidy, a state in which cells exhibit copy number changes of (parts of) chromosomes, is a hallmark of cancer cells and, when present in all cells, leads to miscarriages and congenital disorders, such as Down syndrome. In addition to these well-known roles of aneuploidy, chromosome copy number changes have also been reported in some studies to occur in neurons in healthy human brain and possibly even more in Alzheimer’s disease (AD). However, the studies of aneuploidy in the human brain are currently under debate as earlier findings, mostly based on in situ hybridization approaches, could not be reproduced by more recent single cell sequencing studies with a much higher resolution. Here, we review the various studies on the occurrence of aneuploidy in brain cells from normal individuals and Alzheimer’s patients. We discuss possible mechanisms for the origin of aneuploidy and the pros and cons of different techniques used to study aneuploidy in the brain, and we provide a future perspective

Acute toxicity of chromium on Cnesterodon decemmaculatus (pisces: poeciliidae) (La toxicidad aguda del cromo en Cnesterodon decemmaculatus (pisces: poeciliidae))

Se evaluó la toxicidad aguda del Cr(VI) durante 96 h de exposición continua en ejemplares de madrecitas de agua, Cnesterodon decemmaculatus (Jenyns 1842), pez ovovivíparo de amplia distribución neotropical. Se evaluó la CL50/24-96h por exposición a concentraciones de 0-45,5 mg L-1 de Cr(VI). Los resultados mostraron que la CL-50 alcanzó valores de 35,1, 27,5, 24,0 y 21,4 mg L-1 luego de 24, 48, 72 y 96 h de exposición, respectivamente. No se observó mortalidad tanto en los controles como en aquellos peces expuestos a 3,2 mg L-1. Sin embargo, dicho parámetro alcanzó valores del 63% en aquellos ejemplares expuestos a la mayor concentración luego de 24 h de exposición. Estos resultados sugieren que Cr(VI) podría ser utilizado control positivo en la evaluación de la toxicidad en peces, al menos cuando C. decemmaculatus es empleado como modelo experimental.AbstractThe acute toxicity of Cr(VI) upon 96 h of continuous exposure of the ten-spotted live-bearing fish Cnesterodon decemmaculatus (Jenyns 1842) was evaluated (LC50/96h) in the concentration from 0 to 45.5 mg L-1 Cr(VI) and found to be 21 mg L-1; Upon 24, 48, 72, and 96 h of exposure, the LC50 values are 35.1, 27.5, and 24.0 and 21.4 mg L-1, respectively. No mortality was observed for controls or for the fish exposed at 3.2 mg L-1. Mortality at the highest Cr(VI) concentration within 24 h exposure was 63 % Cr(VI) is suggested to be used as positive control agent in piscine toxicity assessment, at least when C. decemmaculatus is involved

Differences in the carcinogenic evaluation of glyphosate between the International Agency for Research on Cancer (IARC) and the European Food Safety Authority (EFSA)

The International Agency for Research on Cancer (IARC) Monographs Programme identifies chemicals, drugs, mixtures, occupational exposures, lifestyles and personal habits, and physical and biological agents that cause cancer in humans and has evaluated about 1000 agents since 1971. Monographs are written by ad hoc Working Groups (WGs) of international scientific experts over a period of about 12 months ending in an eight-day meeting. The WG evaluates all of the publicly available scientific information on each substance and, through a transparent and rigorous process,1 decides on the degree to which the scientific evidence supports that substance's potential to cause or not cause cancer in humans. For Monograph 112,2 17 expert scientists evaluated the carcinogenic hazard for four insecticides and the herbicide glyphosate.3 The WG concluded that the data for glyphosate meet the criteria for classification as a probable human carcinogen. The European Food Safety Authority (EFSA) is the primary agency of the European Union for risk assessments regarding food safety. In October 2015, EFSA reported4 on their evaluation of the Renewal Assessment Report5 (RAR) for glyphosate that was prepared by the Rapporteur Member State, the German Federal Institute for Risk Assessment (BfR). EFSA concluded that ?glyphosate is unlikely to pose a carcinogenic hazard to humans and the evidence does not support classification with regard to its carcinogenic potential?. Addendum 1 (the BfR Addendum) of the RAR5 discusses the scientific rationale for differing from the IARC WG conclusion. Serious flaws in the scientific evaluation in the RAR incorrectly characterise the potential for a carcinogenic hazard from exposure to glyphosate. Since the RAR is the basis for the European Food Safety Agency (EFSA) conclusion,4 it is critical that these shortcomings are corrected

Telomere - A Complex End of a Chromosome

This book, Telomere - A Complex End of a Chromosome, is organized into nine chapters containing the latest aspects of the current knowledge about the structure of telomeres and the crucial role that telomerase plays not only in maintaining chromosomal stability but also in relation to cell immortality, cell instability, and cancer biology. We now appreciate that these unusual complexes of DNA and proteins we all know as ""telomeres"" are dynamic and key structures that depend on telomerase and other cellular factors for continuance. Regulation of telomere activity is a dynamic area of current research, and new insights into telomeres and their role in aging and cancer, among other biological functions and pathologies, appear regularly in the scientific world. However, one fact is more than understandable in this difficult biological conundrum: the end of the telomere story is far from being totally unraveled

Toxicology - New Aspects to This Scientific Conundrum

This edited book, Toxicology - New Aspects to This Scientific Conundrum, is intended to provide an overview on the different xenobiotics employed every day in our anthropogenic activities. We hope that this book will continue to meet the expectations and needs of all interested in the implications for the living species of known and new toxicants and to guide them in the future investigations

Chromosomal Abnormalities - A Hallmark Manifestation of Genomic Instability

This edited book, Chromosomal Abnormalities - A Hallmark Manifestation of Genomic Instability, contains a series of chapters highlighting several aspects related to the generation of chromosomal abnormalities in genetic material. We are extremely grateful to the authors who had contributed with valuable information about the role of genomic instability in pathological disorders as well as in the evolution process