Collaborative environmental DNA sampling from petal surfaces of flowering cherry <Emphasis Type="Italic">Cerasus</Emphasis> × <Emphasis Type="Italic">yedoensis</Emphasis> ‘Somei-yoshino’ across the Japanese archipelago

Recent studies have shown that environmental DNA is found almost everywhere. Flower petal surfaces are an attractive tissue to use for investigation of the dispersal of environmental DNA in nature as they are isolated from the external environment until the bud opens and only then can the petal surface accumulate environmental DNA. Here, we performed a crowdsourced experiment, the “Ohanami Project”, to obtain environmental DNA samples from petal surfaces of Cerasus?×?yedoensis ‘Somei-yoshino’ across the Japanese archipelago during spring 2015. C. × yedoensis is the most popular garden cherry species in Japan and clones of this cultivar bloom simultaneously every spring. Data collection spanned almost every prefecture and totaled 577 DNA samples from 149 collaborators. Preliminary amplicon-sequencing analysis showed the rapid attachment of environmental DNA onto the petal surfaces. Notably, we found DNA of other common plant species in samples obtained from a wide distribution; this DNA likely originated from the pollen of the Japanese cedar. Our analysis supports our belief that petal surfaces after blossoming are a promising target to reveal the dynamics of environmental DNA in nature. The success of our experiment also shows that crowdsourced environmental DNA analyses have considerable value in ecological studies.     

Quantitative trait loci determining weight reduction of testes and pituitary by diethylstilbesterol in LEXF and FXLE recombinant inbred strain rats.

Increasing exposure to environmental endocrine disruptor, xeno-estrogen, is a serious hazard to male reproductive activity. To explore possible genetic control in susceptibility to xeno-estrogen, the weight reduction of testes induced by the continuous administration of a synthetic estrogen, diethylstilbesterol, were investigated by quantitative trait analysis in LEXF and FXLE recombinant inbred strain rats, consisting of 21 independent strains, 9 of their substrains, parental F344/Stm and LE/Stm strains, and (F344 x LE)F1. For the weight of testes, one highly significant quantitative trait locus (QTL) and one significant QTL were mapped on chromosomes 7 and 1, respectively. The QTL on chromosome 7 is closely associated with c-myc. Pituitary weight and serum prolactin were also variable among recombinant inbred strains, but no QTL was detected for them in this study.     

Cu/Zn‐ and Mn‐superoxide dismutases are specifically up‐regulated in neurons after focal brain injury

In previous studies, we have demonstrated that damaged neurons within a boundary area around necrosis fall into delayed cell death due to the cytotoxic effect of microglial nitric oxide (NO), and are finally eliminated by activated microglia. In contrast, neurons in a narrow surrounding region nearby this boundary area remain alive even though they may encounter cytotoxic NO. To investigate the mechanism by which neurons tolerate this oxidative stress, we examined the in vitro and in vivo expression levels of superoxide dismutase (SOD) under pathological conditions. Results from our in situ hybridization and immunohistochemical studies showed up‐regulation of Cu/Zn‐SOD only in neurons outside the boundary area, whereas up‐regulation of Mn‐SOD was detected in both neurons and glial cells in the same region. In vitro experiments using rat PC12 pheochromocytoma and C6 glioma cell lines showed that induction of both Cu/Zn‐ and Mn‐SOD mRNA could only be detected in PC12 cells after treatment with NO donors, while a slight induction of Mn‐SOD mRNA alone could be seen in C6 glioma cells. The mechanism of resistance toward oxidative stress therefore appears to be quite different between neuronal and glial cells. It is assumed that these two types of SOD might play a critical role in protecting neurons from NO cytotoxicity in vivo, and the inability of SOD induction in damaged neurons seems to cause their selective elimination after focal brain injury. © 2000 John Wiley & Sons, Inc. J Neurobiol 45: 39–46, 2000     

Improved specimen preparation for cryo-electron microscopy using a symmetric carbon sandwich technique

Image shift due to beam-induced specimen charging has become the most severe problem in electron microscopy for imaging two-dimensional (2D) crystals of biological macromolecules, especially in the case of highly tilted specimens. Image shift causes diffraction spots perpendicular to the tilt axis to disappear even at medium or low resolution. The yield of good images from tilted specimens prepared on a single layer of continuous carbon support film is therefore very low. In this paper, we have used 2D crystals of aquaporin-4 to investigate the effect of a carbon sandwich preparation method on specimen charging. We find that a larger number of images show sharp diffraction spots perpendicular to the tilt axis if crystals are placed in between two sheets of carbon film as compared to images taken from specimens prepared by the conventional single carbon support film technique. Our results demonstrate that the reproducible carbon sandwich preparation technique overcomes the severe specimen charging problem and thus has the potential to significantly speed up structure analysis by electron crystallography.