The Role of Prostaglandin E2 on the Developing Hippocampus - Link to Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by deficits in social communication, increased repetitive/restricted behaviours and anxiety. The prevalence of autism has been drastically increasing over the past few decades with an associated increase in socioeconomic burden, imposing hardship on many families. Currently, 1 in 66 Canadians are impacted by the disorder and males are four times as likely to be diagnosed with ASD. There is a growing need to understand the underlying mechanisms during development that are contributing to the pathology of ASD in both sexes. Clinical and epidemiological studies suggest exposure to environmental risk factors during pregnancy can impact lipid signaling during development, contributing to the pathology of ASD in children. Previous literature has provided evidence that a bioactive lipid signalling molecule in the brain, known as prostaglandin E2 (PGE2) can be perturbed due to exposure to environmental risk factors during pregnancy, impacting critical processes such as neuronal migration, differentiation and proliferation. Moreover, deficits in hippocampal function are known to contribute to the major symptoms that characterize ASD. In this study, we investigated how prenatal exposure to PGE2 impacts the developing hippocampus in males and females. We examined the effect of PGE2 exposure on dendritic morphology using Golgi-cox staining and proteins that may be driving these morphological changes using western blotting. Our findings suggest that prenatal PGE2 exposure impacts hippocampal dendritic morphology in a sex-dependent manner, which is associated with changes in the expression of proteins involved in cytoskeletal architecture. Ultimately, this study provides us with insight on how perturbed PGE2 signaling impacts cytoskeletal dynamics in the developing hippocampus, contributing to the pathology of autism

The Role of Prostaglandin E2 on the Developing Hippocampus - Link to Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by deficits in social communication, increased repetitive/restricted behaviours and anxiety. The prevalence of autism has been drastically increasing over the past few decades with an associated increase in socioeconomic burden, imposing hardship on many families. Currently, 1 in 66 Canadians are impacted by the disorder and males are four times as likely to be diagnosed with ASD. There is a growing need to understand the underlying mechanisms during development that are contributing to the pathology of ASD in both sexes. Clinical and epidemiological studies suggest exposure to environmental risk factors during pregnancy can impact lipid signaling during development, contributing to the pathology of ASD in children. Previous literature has provided evidence that a bioactive lipid signalling molecule in the brain, known as prostaglandin E2 (PGE2) can be perturbed due to exposure to environmental risk factors during pregnancy, impacting critical processes such as neuronal migration, differentiation and proliferation. Moreover, deficits in hippocampal function are known to contribute to the major symptoms that characterize ASD. In this study, we investigated how prenatal exposure to PGE2 impacts the developing hippocampus in males and females. We examined the effect of PGE2 exposure on dendritic morphology using Golgi-cox staining and proteins that may be driving these morphological changes using western blotting. Our findings suggest that prenatal PGE2 exposure impacts hippocampal dendritic morphology in a sex-dependent manner, which is associated with changes in the expression of proteins involved in cytoskeletal architecture. Ultimately, this study provides us with insight on how perturbed PGE2 signaling impacts cytoskeletal dynamics in the developing hippocampus, contributing to the pathology of autism

C9orf72, a protein associated with amyotrophic lateral sclerosis (ALS) is a guanine nucleotide exchange factor

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), two late onset neurodegenerative diseases, have been shown to share overlapping cellular pathologies and genetic origins. Studies suggest that a hexanucleotide repeat expansion in the first intron of the C9orf72 gene is the most common cause of familial FTD and ALS pathology. The C9orf72 protein is predicted to be a differentially expressed in normal and neoplastic cells domain protein implying that C9orf72 functions as a guanine nucleotide exchange factor (GEF) to regulate specific Rab GTPases. Reported studies thus far point to a putative role for C9orf72 in lysosome biogenesis, vesicular trafficking, autophagy and mechanistic target of rapamycin complex1 (mTORC1) signaling. Here we report the expression, purification and biochemical characterization of C9orf72 protein. We conclusively show that C9orf72 is a GEF. The distinctive presence of both Rab- and Rho-GTPase GEF activities suggests that C9orf72 may function as a dual exchange factor coupling physiological functions such as cytoskeleton modulation and autophagy with endocytosis

Adaptive Copy Number Evolution in Malaria Parasites

Copy number polymorphism (CNP) is ubiquitous in eukaryotic genomes, but the degree to which this reflects the action of positive selection is poorly understood. The first gene in the Plasmodium folate biosynthesis pathway, GTP-cyclohydrolase I (gch1), shows extensive CNP. We provide compelling evidence that gch1 CNP is an adaptive consequence of selection by antifolate drugs, which target enzymes downstream in this pathway. (1) We compared gch1 CNP in parasites from Thailand (strong historical antifolate selection) with those from neighboring Laos (weak antifolate selection). Two percent of chromosomes had amplified copy number in Laos, while 72% carried multiple (2–11) copies in Thailand, and differentiation exceeded that observed at 73 synonymous SNPs. (2) We found five amplicon types containing one to greater than six genes and spanning 1 to >11 kb, consistent with parallel evolution and strong selection for this gene amplification. gch1 was the only gene occurring in all amplicons suggesting that this locus is the target of selection. (3) We observed reduced microsatellite variation and increased linkage disequilibrium (LD) in a 900-kb region flanking gch1 in parasites from Thailand, consistent with rapid recent spread of chromosomes carrying multiple copies of gch1. (4) We found that parasites bearing dhfr-164L, which causes high-level resistance to antifolate drugs, carry significantly (p = 0.00003) higher copy numbers of gch1 than parasites bearing 164I, indicating functional association between genes located on different chromosomes but linked in the same biochemical pathway. These results demonstrate that CNP at gch1 is adaptive and the associations with dhfr-164L strongly suggest a compensatory function. More generally, these data demonstrate how selection affects multiple enzymes in a single biochemical pathway, and suggest that investigation of structural variation may provide a fast-track to locating genes underlying adaptation

Molecular mechanisms of cell death: recommendations of the Nomenclature Committee on Cell Death 2018.

Over the past decade, the Nomenclature Committee on Cell Death (NCCD) has formulated guidelines for the definition and interpretation of cell death from morphological, biochemical, and functional perspectives. Since the field continues to expand and novel mechanisms that orchestrate multiple cell death pathways are unveiled, we propose an updated classification of cell death subroutines focusing on mechanistic and essential (as opposed to correlative and dispensable) aspects of the process. As we provide molecularly oriented definitions of terms including intrinsic apoptosis, extrinsic apoptosis, mitochondrial permeability transition (MPT)-driven necrosis, necroptosis, ferroptosis, pyroptosis, parthanatos, entotic cell death, NETotic cell death, lysosome-dependent cell death, autophagy-dependent cell death, immunogenic cell death, cellular senescence, and mitotic catastrophe, we discuss the utility of neologisms that refer to highly specialized instances of these processes. The mission of the NCCD is to provide a widely accepted nomenclature on cell death in support of the continued development of the field

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data