Biology subjects

Nishizawa, N.

Publications and source records attributed to Nishizawa, N..

4 recordsLinked to original sources

bioRxiv2026

Improving sensitivity in environmental DNA measurement by reconcentrating DNA extracts

Environmental DNA (eDNA) methodology is widely applied in the biomonitoring of organisms, but it requires the target DNA to be detected in a simple, stable, and highly sensitive manner. Detection sensitivity of eDNA measurement becomes particularly critical when monitoring species present at low abundance. In this study, we aimed to improve the detection sensitivity through a method of DNA-extract reconcentration. This approach involves reconcentrating eDNA samples that were originally extracted using the widely adopted DNeasy Blood and Tissue Kit (Qiagen), utilizing the same kits reagents, and does not require any additional equipment or reagents. We evaluated the ability of this DNA reconcentration method using field samples including river, lake and costal marine habitats. Evaluation of this DNA reconcentration method showed that when ten conventionally extracted samples were pooled, the DNA concentration increased by approximately sevenfold, as confirmed by DNA quantification and quantitative PCR analyses, demonstrating enhanced detection sensitivity.

ecology↗

bioRxiv2021

Filtration extraction method using microfluidic channel for measuring environmental DNA

The environmental DNA (eDNA) method, which is widely applied for biomonitoring, is limited to laboratory analysis and processing. In this study, we developed a filtration/extraction component using a microfluidic channel, Biryu-Chip (BC), and a filtration/extraction method, BC method, to minimize the volume of the sample necessary for DNA extraction and subsequent PCR amplification. We tested the performance of the BC method and compared it with the Sterivex filtration/extraction method using aquarium and river water samples. We observed that using the BC method, the same concentration of the extracted DNA was obtained with 1/20-1/40 of the filtration volume of the Sterivex method, suggesting that the BC method can be widely used for eDNA measurement. In addition, we could perform on-site measurements of eDNA within 30 min using a mobile PCR device. Using the BC method, filtration and extraction could be performed easily and quickly. The PCR results obtained by the BC method were similar to those obtained by the Sterivex method. The BC method required fewer steps and therefore, the risk of DNA contamination could be reduced. When combined with a mobile PCR, the BC method can be applied to easily detect eDNA within 30 min from a few 10 mL of the water sample, even on-site.

ecology↗

bioRxiv2020

On-site eDNA detection of species using ultra-rapid mobile PCR

Molecular methods, including environmental DNA (eDNA) methods, provide essential information for biological and conservation sciences. Molecular measurements are often performed in the laboratory, which limits their scope, especially for rapid on-site analysis. eDNA methods for species detection provide essential information for the management and conservation of species and communities in various environments. We developed an innovative novel method for on-site eDNA measurements using an ultra-rapid mobile PCR platform. We tested the ability of our method to detect the distribution of silver carp, Hypophthalmichthys molitrix, an invasive fish in Japanese rivers and lakes. Our method reduced the measurement time to 30 min and provided high detectability of aquatic organisms compared to the national observation surveys using multiple fishing nets and laboratory extraction/detection using a benchtop qPCR platform. Our on-site eDNA method can be immediately applied to various taxa and environments.

ecology↗

bioRxiv2018

RAMP1 in Kupffer cells is a critical regulator in immune-mediated hepatitis

The significanceF of the relationship between the nervous and immune systems with respect to disease course is increasingly apparent. Immune cells in the liver and spleen are responsible for the development of acute liver injury, yet the regulatory mechanisms of the interactions remain elusive. Calcitonin gene-related peptide (CGRP), which is released from the sensory nervous system, regulates innate immune activation via receptor activity-modifying protein 1 (RAMP1), a subunit of the CGRP receptor. Here, we show that RAMP1 in Kupffer cells (KCs) plays a critical role in the etiology of immune-mediated hepatitis. RAMP1-deficient mice with concanavalin A (ConA)-mediated hepatitis, characterized by severe liver injury accompanied by infiltration of immune cells and increased secretion of pro-inflammatory cytokines by KCs and splenic T cells, showed poor survival. Removing KCs ameliorated liver damage, while depleting T cells or splenectomy led to partial amelioration. Adoptive transfer of splenic T cells from RAMP1-deficient mice led to a modest increase in liver injury. Co-culture of KCs with splenic T cells led to increased cytokine expression by both cells in a RAMP1-dependent manner. Thus, immune-mediated hepatitis develops via crosstalk between immune cells. RAMP1 in KCs is a key regulator of immune responses.

immunology↗