Visualisation of gene expression within the context of tissues using an X-ray computed tomography-based multimodal approach

The development of an organism is orchestrated by the spatial and temporal expression of genes. Accurate visualisation of gene expression patterns in the context of the surrounding tissues offers a glimpse into the mechanisms that drive morphogenesis. We developed correlative light-sheet fluorescence microscopy and X-ray computed tomography approach to map gene expression patterns to the whole organism`s 3D anatomy. We show that this multimodal approach is applicable to gene expression visualized by protein-specific antibodies and fluorescence RNA in situ hybridisation offering a detailed understanding of individual phenotypic variations in model organisms. Furthermore, the approach offers a unique possibility to identify tissues together with their 3D cellular and molecular composition in anatomically less-defined in vitro models, such as organoids. We anticipate that the visual and quantitative insights into the 3D distribution of gene expression within tissue architecture, by multimodal approach developed here, will be equally valuable for reference atlases of model organisms development, as well as for comprehensive screens, and morphogenesis studies of in vitro models.

The first comprehensive population size estimations for the highly endangered largest diving beetle Dytiscus latissimus in Europe

Dytiscus latissimus (Coleoptera Dytiscidae) is an endangered diving beetle throughout its range. It is one of the two species of Dytiscidae listed in Annex II of the Habitats Directive, IUCN red list and in many national level legislations and therefore strictly protected. The conservation of endangered species first of all requires an assessment of their population size. Until now, a method has not been developed for estimating the size of D. latissimus populations. The article summarizes the results of two studies carried out independently in Germany and Latvia. Both studies were carried out in one water body used recapture method but with a different spatial placement of traps, which, according to our data, is an important factor in population estimation. We evaluated Jolly-Seber and Schnabel approaches of estimating aquatic beetle's populations and found that confidence intervals obtained by different methods in our research do not differ significantly, but combination of both models provide the most accurate estimates of population dynamics. As part of the study, we concluded that the populations of Dytiscus latissimus are relatively closed, so we accept that the Schnabel estimate shows more accurate data. By fixing the places of capture of each individual, it was found that females live mainly locally, and males actively move within the water body. This aspect indicates the advantage of the spatial placement of traps compared to the use of transects. The results of our study show a significantly higher number of both captured and recaptured males Such a sex ratio may indicate both a greater activity of males and differences in the sex ratio in the population. The study confirmed that environmental changes, such as the water level in a water body, can also significantly affect the result of a population assessment. In the frame of D. latissimus monitoring, to obtain an objective estimation of the species population size we recommend using four traps for each 100 m of water body shoreline with 4-8 censuses, dependently on the recapture rate.

The First Ptilodactyla Illiger, 1807 (Coleoptera: Dryopoidea: Ptilodactylidae) Described from Eocene Baltic Amber

The beetle family Ptilodactylidae contains more than 500 extant species; however, its fossil record is scarce and remains understudied. In this study, we describe a new species of Ptilodactylidae, Ptilodactyla eocenica Kundrata, Bukejs and Blank, sp. nov., based on a relatively well-preserved specimen from Baltic amber. We use X-ray microcomputed tomography to reconstruct its morphology since some of the principal diagnostic characters have been obscured by opaque bubbles. It is the third ptilodactylid species described from Baltic amber, and the first one belonging to the subfamily Ptilodactylinae. Additionally, we summarize the classification, diversity, and distribution of both extinct and extant Ptilodactylidae.

A new species of Eusphalerum Kraatz, 1857 from the Eocene Baltic amber (Coleoptera, Staphylinidae, Omaliinae)

A new species of the genus Eusphalerum Kraatz, 1857 (Omaliinae) from the Eocene Baltic amber is described and illustrated: Eu. bukejsi Shavrin, sp.n. The specimen was studied using X-ray micro-computed tomography (μCT), to obtain images of the habitus, body parts and aedeagus. Based on the shape of the aedeagus, it was compared with East Asian species of pollens and japonicum groups.

The invisibile becomes visible: X-ray micro-CT reconstruction of emAneurus/em emdamzeni/em sp. nov. (Hemiptera: Heteroptera: Aradidae) from Eocene Baltic amber

The subfamily Aneurinae of the flat bug family Aradidae (Hemiptera: Heteroptera) contains about 150 extant species assigned to seven genera, and seven fossil species of which six were described from Eocene Baltic amber and one from Cretaceous Burmese amber. A new species Aneurus damzeni sp. nov. from Baltic amber is described and illustrated using X-ray micro-computed tomography (μCT) reconstructing concealed morphological characters. A key to all five extant and fossil Aneurinae species with triangular scutellum is provided.