Brain-wide representations of behavior spanning multiple timescales and states in C. elegans.

Changes in an animal's behavior and internal state are accompanied by widespread changes in activity across its brain. However, how neurons across the brain encode behavior and how this is impacted by state is poorly understood. We recorded brain-wide activity and the diverse motor programs of freely moving C. elegans and built probabilistic models that explain how each neuron encodes quantitative behavioral features. By determining the identities of the recorded neurons, we created an atlas of how the defined neuron classes in the C. elegans connectome encode behavior. Many neuron classes have conjunctive representations of multiple behaviors. Moreover, although many neurons encode current motor actions, others integrate recent actions. Changes in behavioral state are accompanied by widespread changes in how neurons encode behavior, and we identify these flexible nodes in the connectome. Our results provide a global map of how the cell types across an animal's brain encode its behavior

Cdt1 overexpression drives colorectal carcinogenesis through origin overlicensing and DNA damage

Chromatin licensing and DNA replication factor 1 (CDT1), a protein of the pre-replicative complex, is essential for loading the minichromosome maintenance complex (MCM) helicases onto the origins of DNA replication. While several studies have shown that dysregulation of CDT1 expression causes re-replication and DNA damage in cell lines, and CDT1 is highly expressed in several human cancers, whether CDT1 deregulation is sufficient to enhance tumorigenesis in vivo is currently unclear. To delineate its role in vivo, we overexpressed Cdt1 in the mouse colon and induced carcinogenesis using azoxymethane/dextran sodium sulfate (AOM/DSS). Here, we show that mice overexpressing Cdt1 develop a significantly higher number of tumors with increased tumor size, and more severe dysplastic changes (high-grade dysplasia), compared with control mice under the same treatment. These tumors exhibited an increased growth rate, while cells overexpressing Cdt1 loaded greater amounts of Mcm2 onto chromatin, demonstrating origin overlicensing. Adenomas overexpressing Cdt1 showed activation of the DNA damage response (DDR), apoptosis, formation of micronuclei, and chromosome segregation errors, indicating that aberrant expression of Cdt1 results in increased genomic and chromosomal instability in vivo, favoring cancer development. In line with these results, high-level expression of CDT1 in human colorectal cancer tissue specimens and colorectal cancer cell lines correlated significantly with increased origin licensing, activation of the DDR, and microsatellite instability (MSI). © 2022 The Pathological Society of Great Britain and Ireland. © 2022 The Pathological Society of Great Britain and Ireland

Diabetes associated metabolomic perturbations in NOD mice

Non-obese diabetic (NOD) mice are a widely-used model oftype1 diabetes (T1D). However, not all animals develop overt diabetes. This study examined the circulating metabolomic profiles of NOD mice progressing or not progressing to T1D. Total beta-cell mass was quantified in the intact pancreas using transgenic NOD mice expressinggreen fluorescent protein under the control of mouse insulin I promoter.While both progressor and non-progressor animals displayed lymphocyte infiltration and endoplasmic reticulum stress in the pancreas tissue;overt T1D did not develop until animals lost ~70% of the total beta-cell mass.Gas chromatography time of flight mass spectrometry (GC-TOF) was used to measure >470 circulating metabolites in male and female progressor and non-progressor animals (n=76) across a wide range of ages (neonates to >40-wk).Statistical and multivariate analyses were used to identify age and sex independent metabolic markers which best differentiated progressor and non-progressor animals’ metabolic profiles. Key T1D-associated perturbations were related with: (1) increased plasma glucose and reduced 1,5-anhydroglucitol markers of glycemic control; (2) increased allantoin, gluconic acid and nitric oxide-derived saccharic acid markers of oxidative stress; (3) reduced lysine, an insulin secretagogue; (4) increased branched-chain amino acids, isoleucine and valine; (5) reduced unsaturated fatty acids including arachidonic acid; and (6)perturbations in urea cycle intermediates suggesting increased arginine-dependent NO synthesis. Together these findings highlight the strength of the unique approach of comparing progressor and non-progressor NOD mice to identify metabolic perturbations involved in T1D progression