Cathepsin D in pancreatic acinar cells is implicated in cathepsin B and L degradation, but not in autophagic activity.

Cathepsin D (CD) is the major lysosomal aspartic protease and is widely distributed in the cells of various mammalian tissues. CD participates in various physiological events such as regulation of programmed cell death, activation of enzymatic precursors, and metabolic degradation of intracellular proteins through macroautophagy. To investigate the role of CD in pancreatic acinar cells, which constitute the exocrine pancreas, we generated and examined mice specifically deficient for CD in pancreatic acinar cells. CD deficient mice showed normal pancreatic development and autophagic activity, although LC3-II, which is a marker of the autophagosome, accumulates in both physiological and pancreatitis conditions. Moreover, CD deficiency leads to accumulation of matured cathepsin B (CB) and cathepsin L (CL) which are members of the cysteine protease family. We therefore conclude that CD in pancreatic acinar cells is implicated in CB and CL degradation but not in autophagic activity.

Correction: Water pre-filtration methods to improve environmental DNA detection by real-time PCR and metabarcoding.

[This corrects the article DOI: 10.1371/journal.pone.0250162.].

Water pre-filtration methods to improve environmental DNA detection by real-time PCR and metabarcoding.

Environmental DNA (eDNA) analysis is a novel approach for biomonitoring and has been mostly used in clear water. It is difficult to detect eDNA in turbid water as filter clogging occurs, and environmental samples contain various substances that inhibit the polymerase chain reaction (PCR) and affect the accuracy of eDNA analysis. Therefore, we applied a pre-filtration method to better detect the fish species (particularly pale chub, Opsariichthys platypus) present in a water body by measuring eDNA in environmental samples containing PCR inhibitors. Upon conducting 12S rRNA metabarcoding analysis (MiFish), we found that pre-filtration did not affect the number or identities of fish species detected in our samples, but pre-filtration through pore sizes resulted in significantly reduced variance among replicate samples. Additionally, PCR amplification was improved by the pre-filtration of environmental samples containing PCR inhibitors such as humic substances. Although this study may appear to be a conservative and ancillary experiment, pre-filtration is a simple technique that can not only improve the physical properties of water, such as turbidity, but also the quality of eDNA biomonitoring.

Novel enzymatic properties of DNA-Pt complexes.

DNA-Pt complexes have shown novel enzymatic activity as a peroxidase similar to that of horseradish peroxidase in the colorimetric reaction with its substrate. The enzymatic activity of these complexes increased with increasing reaction time and pH in reaction solutions of DNA and K2[PtCl4]. This enhanced enzymatic activity was attributed to the increase in Pt conjugated to DNA in the complex. The enzymatic activity per unit mole of the DNA-Pt complex was significantly higher for complexes prepared with high molecular weight DNA because the enzymatic activity of the complex per repeat unit of DNA was almost constant for these complexes prepared under the same reaction conditions. All the DNA-Pt complexes in this study prepared with different DNA sequences (i.e., [A]20, [G]20, [C]20, [T]20, and [AG]10) exhibited peroxidase enzymatic activity. These complexes showed good thermal stability as compared to native horseradish peroxidase.

Defective smooth muscle development in qkI-deficient mice.

The qkI gene encodes an RNA binding protein which was identified as a candidate for the classical neurologic mutation, qkv. Although qkI is involved in glial cell differentiation in mice, qkI homologues in other species play important roles in various developmental processes. Here, we show a novel function of qkI in smooth muscle cell differentiation during embryonic blood vessel formation. qkI null embryos died between embryonic day 9.5 and 10.5. Embryonic day 9.5 qkI null embryos showed a lack of large vitelline vessels in the yolk sacs, kinky neural tubes, pericardial effusion, open neural tubes and incomplete embryonic turning. Using X-gal and immunohistochemical staining, qkI is first shown to be expressed in endothelial cells and smooth muscle cells. Analyses of qkI null embryos in vivo and in vitro revealed that the vitelline artery was too thin to connect properly to the yolk sac, thereby preventing remodeling of the yolk sac vasculature, and that the vitelline vessel was deficient in smooth muscle cells. Addition of QKI and platelet-endothelial cell adhesion molecule-1 positive cells to an in vitro para-aortic splanchnopleural culture of qkI null embryos rescued the vascular remodeling deficit. These data suggest that QKI protein has a critical regulatory role in smooth muscle cell development, and that smooth muscle cells play an important role in inducing vascular remodeling.