Increased insulin sensitivity and diminished pancreatic beta-cell function in DNA repair deficient Ercc1(d/-) mice

Background: Type 2 diabetes (T2DM) is an age-associated disease characterized by hyperglycemia due to insulin resistance and decreased beta-cell function. DNA damage accumulation has been associated with T2DM, but whether DNA damage plays a role in the pathogenesis of the disease is unclear. Here, we used mice deficient for the DNA excision-repair gene Ercc1 to study the impact of persistent endogenous DNA damage accumulation on energy metabolism, glucose homeostasis and beta-cell function. Methods: ERCC1-XPF is an endonuclease required for multiple DNA repair pathways and reduced expression of ERCC1-XPF causes accelerated accumulation of unrepaired endogenous DNA damage and accelerated aging in humans andmice. In this study, energy metabolism, glucose metabolism, beta-cell function and insulin sensitivity were studied in Ercc1(d/-) mice, which model a human progeroid syndrome. Results: Ercc1(d/-) mice displayed suppression of the somatotropic axis and altered energy metabolism. Insulin sensitivitywas increased, whereas, plasma insulin levelswere decreased in Ercc1(d/-) mice. Fasting induced hypoglycemia in Ercc1(d/-) mice, whichwas the result of increased glucose disposal. Ercc1(d/-) mice exhibit a significantly reduced beta-cell area, even compared to control mice of similar weight. Glucose-stimulated insulin secretion in vivo was decreased in Ercc1(d/-) mice. Islets isolated from Ercc1(d/-) mice showed increased DNA damage markers, decreased glucose-stimulated insulin secretion and increased susceptibility to apoptosis. Conclusion: Spontaneous DNA damage accumulation triggers an adaptive response resulting in improved insulin sensitivity. Loss of DNA repair, however, does negatively impacts beta-cell survival and function in Ercc1(d/-) mice. (C) 2021 The Author(s). Published by Elsevier Inc

TRIAL OPERATION OF A SIMPLE AUTOMATIC WEATHER STATION AT ASUKA CAMP, ANTARCTICA

A tentative unmanned observation was carried out at Asuka Camp in 1985 by means of a data logger equipped with a thermometer and an anemometer. The data logger, run by Lithium batteries, was buried in the surface snow without any heater. Although the sensors were covered by heavily drifting snow during the later period of observation, the desired recordings were performed successfully. Analyses of the obtained data provided information on diurnal variations of air temperature, periods and behavior of disturbances, monthly mean air temperature and depth of snow drift at Asuka Camp in 1985

The First Symbiont-Free Genome Sequence of Marine Red Alga, Susabi-nori (<i>Pyropia yezoensis</i>)

<div><p>Nori, a marine red alga, is one of the most profitable mariculture crops in the world. However, the biological properties of this macroalga are poorly understood at the molecular level. In this study, we determined the draft genome sequence of susabi-nori (<i>Pyropia yezoensis</i>) using next-generation sequencing platforms. For sequencing, thalli of <i>P. yezoensis</i> were washed to remove bacteria attached on the cell surface and enzymatically prepared as purified protoplasts. The assembled contig size of the <i>P. yezoensis</i> nuclear genome was approximately 43 megabases (Mb), which is an order of magnitude smaller than the previously estimated genome size. A total of 10,327 gene models were predicted and about 60% of the genes validated lack introns and the other genes have shorter introns compared to large-genome algae, which is consistent with the compact size of the <i>P. yezoensis</i> genome. A sequence homology search showed that 3,611 genes (35%) are functionally unknown and only 2,069 gene groups are in common with those of the unicellular red alga, <i>Cyanidioschyzon merolae</i>. As color trait determinants of red algae, light-harvesting genes involved in the phycobilisome were predicted from the <i>P. yezoensis</i> nuclear genome. In particular, we found a second homolog of phycobilisome-degradation gene, which is usually chloroplast-encoded, possibly providing a novel target for color fading of susabi-nori in aquaculture. These findings shed light on unexplained features of macroalgal genes and genomes, and suggest that the genome of <i>P. yezoensis</i> is a promising model genome of marine red algae.</p></div