New neurons in old brains: A cautionary tale for the analysis of neurogenesis in post-mortem tissue.

Adult neurogenesis has primarily been examined in two key regions in the mammalian brain, the subgranular zone of the hippocampus and the subventricular zone. The proliferation and integration of newly generated neurons has been observed widely in adult mammalian species including the human hippocampus. Recent high-profile studies have suggested however, that this process is considerably reduced in humans, occurring in children but declining rapidly and nearly completely in the adult brain. In comparison, rodent studies also show age-related decline but a greater degree of proliferation of new neurons in adult animals. Here, we examine whether differences in tissue fixation, rather than biological difference in human versus rodent studies might account for the diminished levels of neurogenesis sometimes observed in the human brain. To do so we analyzed neurogenesis in the hippocampus of rats that were either perfusion-fixed or the brains extracted and immersion-fixed at various post-mortem intervals. We observed an interaction between animal age and the time delay between death and tissue fixation. While similar levels of neurogenesis were observed in young rats regardless of fixation, older rats had significantly fewer labeled neurons when fixation was not immediate. Furthermore, the morphological detail of the labeled neurons was significantly reduced in the delayed fixation conditions at all ages. This study highlights critical concerns that must be considered when using post-mortem tissue to quantify adult neurogenesis.

MANAGEMENT OF MESH FEATURES IN 3D REALITY-BASED POLYGONAL MODELS TO SUPPORT NON-INVASIVE STRUCTURAL DIAGNOSIS AND EMERGENCY ANALYSIS IN THE CONTEXT OF EARTHQUAKE HERITAGE IN ITALY

In the context of non-invasive documentation for the prevention of built heritage, digital surveying and the development of 3D models are widely applied. They have highlighted, with increasing reliability, the opportunities for knowledge and mapping on emerging damages related to safety and structural integrity. However, these processes can reach high-quality results on morphological structural detail, useful as source data for static analysis on the built structures. In this way, 3D models serve as source data for preliminary diagnostics on the causes of drift and deformation mechanisms.The research aims to validate the proposed strategy on the case study of a masonry historical building damaged by the 2016 earthquake in Central Italy, to configure the mesh modeling strategy as a scientific example capable of orienting 3D modeling practices for structural non-invasive diagnosis, also in emergency requirements of intervention. The analysis of the damage mechanisms was performed by exploiting the morphological detail of the virtual surfaces to operate a direct segmentation, automated through the recognition of Feature Regions entities. It was based on the collaboration among professionals and technicians of the Emergency Support Department of EUCENTRE and DAda-LAB researchers of University of Pavia, to evaluate appropriate procedures of digital documentation for on-site survey in sites affected by emergency conditions of post-earthquake damage.

Immuno-correlative light and electron microscopy (iCLEM) using STEM v1

Immuno- correlative light and electron microscopy (iCLEM) combines ultrastructural information obtained from high resolution electron microscopy and the use of genetically encoded or cytochemical markers. Immuno-CLEM takes advantage of the antigenicity preserved by Tokuyasu sample preparation to identify, quantify and characterise heterogeneous cell populations in small organisms, organs and tissue of healthy and diseased states. iCLEM can be used in combination with scanning EM (SEM), scanning TEM (STEM), and transmission EM (TEM). These protocols are well-suited, for example, for investigating neural stem and progenitor cell populations of the vertebrate nerve system and are available as separate protocols on protocol.io. Here, a method for iCLEM-STEM is described using an adult zebrafish telencephalon brain as a model. This organ is small in size allowing the complete dorsal telencephalic niche to be visualised in sections, and has diverse cell profiles and regenerative potential of local neural stem and progenitor cells. iCLEM-STEM involves the examination of ultrathin tissue sections (62-70 nm) using immunofluorescence labelling and subsequent SEM imaging to obtain a high resolution overview of these sections with greater morphological detail compared to iCLEM-SEM. This protocol should be of particular interest to EM facilities with SEM, but not TEM access.

Thismia belumensis (Thismiaceae), a remarkable new species from The Royal Belum State Park, Gerik, Perak, Peninsular Malaysia

This report describes Thismia belumensis Siti-Munirah & Suhaimi-Miloko, a novel species of achlorophyllous herb discovered in the Royal Belum State Park, Peninsular Malaysia. This new species is unlike any previously described species of Thismia. In particular, T. belumensis possesses a unique annulus, which has been expanded and modified into a cucullate (hood-like) structure. This structure covers the apical floral tube and has an opening on one side facing a thickened part of the annulus, and the off-centre floral aperture confers a zygomorphic symmetry to the flower, indicating T. belumensis is more similar to Thismia labiata J.J.Sm. This morphological detail makes this new species distinct from all other described species of Thismia. In this report, we provide descriptions, illustrations, colour plates, and the provisional conservation status of Thismia belumensis.

Imaging of SARS-CoV-2 infected Vero E6 cells by helium ion microscopy

Helium ion microscopy (HIM) offers the opportunity to obtain direct views of biological samples such as cellular structures, virus particles, and microbial interactions. Imaging with the HIM combines sub-nanometer resolution, large depth of field, and high surface sensitivity. Due to its charge compensation capability, the HIM can image insulating biological samples without additional conductive coatings. Here, we present an exploratory HIM study of SARS-CoV-2 infected Vero E6 cells, in which several areas of interaction between cells and virus particles, as well as among virus particles, were imaged. The HIM pictures show the three-dimensional appearance of SARS-CoV-2 and the surface of Vero E6 cells at a multiplicity of infection of approximately 1 with great morphological detail. The absence of a conductive coating allows for a distinction between virus particles bound to the cell membrane and virus particles lying on top of the membrane. After prolonged imaging, it was found that ion-induced deposition of hydrocarbons from the vacuum renders the sample sufficiently conductive to allow for imaging even without charge compensation. The presented images demonstrate the potential of the HIM in bioimaging, especially for the imaging of interactions between viruses and their host organisms.

Imaging of SARS-CoV-2 infected Vero E6 Cells by Helium Ion Microscopy

Helium ion microscopy (HIM) offers the opportunity to obtain direct views of biological samples such as cellular structures, virus particles, and microbial interactions. Imaging with the HIM combines sub-nanometer resolution, large depth of field, and high surface sensitivity. Due to its charge compensation capability, the HIM can image insulating biological samples without additional conductive coatings. Here, we present an exploratory HIM study of SARS-CoV-2 infected Vero E6 cells, in which several areas of interactions between cells and virus particles, as well as among virus particles, were imaged. The HIM pictures show the three-dimensional appearance of SARS-CoV-2 and the surface of Vero E6 cells at a multiplicity of infection of approximately 1 with great morphological detail. The absence of a conductive coating allows a distinction between virus particles bound to the cell membrane and virus particles lying on top of the membrane. After prolonged imaging, it was found that ion-induced deposition of hydrocarbons from the vacuum renders the sample sufficiently conductive to allow imaging even without charge compensation. The presented images demonstrate the potential of the HIM in bioimaging, especially for the imaging of interactions between viruses and their host organisms.

Redescription of larva of the South African endemic dobsonfly genus Chloroniella Esben-Petersen, 1924 (Megaloptera, Corydalidae), with a proposed terminology for Corydalidae larval sclerites

Chloroniella Esben-Petersen is a relict, monotypic genus of Corydalidae (Megaloptera), considered sister to the remaining dobsonfly genera (Corydalinae); it is the only genus of Corydalinae known from the Afrotropical region. The larva of its only species, C. peryngueyi Esben-Petersen, 1924, was originally described by Barnard in 1931. Herein we redescribe the larva of C. peryngueyi using Scanning Electron Microscopy (SEM), colored focus-stacked images, and drawings in order to provide greater morphological detail of this significant species. Also, we propose a standardized terminology for Corydalidae larval sclerites.

Borders as opposed to so-called geography: which should be used to classify isolated ventricular septal defects?

OBJECTIVES Ventricular septal defects can be classified according to their borders or according to the fashion in which they open to the right ventricle, so-called geography. As yet, there is no consensus as to how they should be classified. In an attempt to achieve agreement, the International Society for Nomenclature of Congenital and Paediatric Heart Disease, in 2018, proposed a system incorporating both approaches. We have assessed the subjectivity of their suggested terms hoping to determine their suitability in the desired universal system for classification. METHODS We examined 212 specimens held in the archive of Birmingham Women’s and Children’s Hospital. Each defect was described by 3 independent examiners on the basis of borders and their relationship to the landmarks of the right ventricle. The interobserver agreement was then calculated using Fleiss' method. RESULTS Calculations to assess interobserver agreement showed that the examiners were more likely to agree on the borders of the defects than their so-called geography (κ = 0.804 vs κ = 0.518). The landmarks of the right ventricle proved to be highly variable such that the application of ‘geographic’ terms to hearts with perimembranous defects proved particularly challenging. CONCLUSIONS Interobserver agreement is lower when using terms based on ‘geography’ as opposed to borders. Whilst providing important morphological detail, the terms based on right ventricular landmarks are highly subjective. They should not be prioritized in a universal system of classification. Instead, the defects can be classified simply by using ‘perimembranous’, ‘muscular’, or ‘doubly committed and juxta-arterial’ as first-order terms.

POTENTIAL AND LIMITATIONS OF TERRESTRIAL LASER SCANNING FOR DISCONTINUITY ROUGHNESS ESTIMATION

<p><strong>Abstract.</strong> Terrestrial Laser Scanning (TLS) greatly facilitates the acquisition of detailed and accurate 3D measurements of remote rock outcrops, at an operational range from several meters to a few kilometres. Reliable, quantitative measures of rock discontinuity roughness are necessary to characterize and evaluate the mechanical and hydraulic behavior of the rock mass. The aim of this research is to investigate the TLS potential and limitations for a reliable estimation of small scale roughness. TLS data noise and resolution define the level of extractable morphological detail, and therefore need to be known and associated with roughness value. The stationary variant of Discrete Wavelet Transform (SWT) was applied to estimate TLS noise level and perform wavelet denoising in direction of range measurements. Denoised TLS data were compared to reference surfaces of decreasing resolution (reference grids) in order to define the size of extractable surface detail. Noise and resolution effect on rock surface roughness, wavelet denoising success and extractable roughness scale were investigated with comparative analyses of TLS and reference surfaces. The developed methodology enabled reasonable TLS noise estimation, improved capabilities of TLS for modelling fine features of an irregular rock surface, and indicated the surface scale that can be reliably extracted from the TLS data.</p>

Practical bone marrow cytology in the dog and cat

In companion animal medicine, bone marrow (BM) aspiration cytology is a cost-effective diagnostic tool, which provides excellent morphological detail of cells and infectious agents. The major indications for BM aspiration include unexplained clinical manifestations (e.g., fever, body weight loss), persistent hematological or biochemical abnormalities (e.g., anemia, leukocytosis), diagnosis and/or staging of malignancies (e.g., lymphoma, mast-cell tumor), diagnosis of important infectious diseases such as leishmaniosis (Leishmania infantum) and canine monocytic ehrlichiosis (Ehrlichia canis) and evaluation of canine iron stores. Complications associated with BM aspiration are rare and the equipment and supplies required minimal, hence accounting for the popularity of this procedure in the clinical setting compared to BM core biopsy. This review focuses on the technical details pertaining to the collection of BM aspirate material, including the usual anatomic sites for sampling, the equipment required, the preparation of the animal, the aspiration technique and the BM material processing for good quality slide preparation. The description of the cellular population normally anticipated in the BM of the dog and cat and the systematic approach in evaluating and interpreting the BM cytological findings are also highlighted. In the last part of this review, the current classification guidelines for the canine and feline BM malignancies are briefly outlined.