Biology subjects

Miettinen, A.

Publications and source records attributed to Miettinen, A..

4 recordsLinked to original sources

bioRxiv2023

Loci associated with migration, maturation and appetite control are linked with signals of fine-scale local selection in a large Atlantic salmon population

Insights into the genetic basis of local adaptation and drivers of population differentiation improve our understanding of evolution and the maintenance of biological diversity. Characterising adaptively important genetic variation also allows more efficient planning of conservation and management actions. We used a genome-wide SNP array to analyse the genetic population structure of a large Atlantic salmon (Salmo salar) population in the interconnected Tornio/Torne and Kalix River system of the Baltic Sea basin, and to identify genomic signatures of fine-scale selection within it. We identified signals of selection and genotype-environment associations (GEA) especially on chromosome (Chr) 9, including on a haploblock containing the six6 gene and other loci that have been earlier suggested to be adaptively important in salmonids. We also detected signals of selection in genome regions including other genes of ecological relevance, such as two known appetite-controlling genes in the melanocortin system (pomca on Chr 9 and mc4r on Chr 14), and the maturation-associated gene taar13c-like (on Chr 21). Variation in these and other identified candidate genes may potentially reflect differential selective pressures experienced by salmon from different parts of the large river system, regarding traits related to e.g. vision, feeding and growth, age at maturity and/or migratory timing. This indicates a need for management strategies to consider ecologically important genomic regions such as these, in order to protect adaptive genetic diversity in wild salmon populations.

evolutionary biology↗

bioRxiv2022

Novel methodology for localizing and studying the insect dorsal rim area morphology in 2D and 3D

1.Polarized light-based navigation in insects is facilitated by a specialised polarisation-sensitive part of the eye known as the dorsal rim area (DRA). Existing methods to study the anatomy of the DRA are in most cases destructive and very time consuming. Here, we present a novel method that allows for DRA localization using 3D volumetric images acquired through micro-computed tomography in combination with 2D photographs. We used the method on size polymorphic buff-tailed bumblebees, Bombus terrestris. We found that the size of the DRA can be easily acquired from photographs of the dorsal part of the eye. An allometric analysis of the size of the DRA in relation to body size in B. terrestris showed that the DRA region increases with body size but not at the same rate. Using our method, we localised the DRA in a 3D volume rendering of the eye using 2D photos localization of an individuals DRA onto the volumetric image stack of the head allowed for individual-level descriptions of the ommatidial structures (lens, crystalline cones, rhabdoms) to be performed on three different eye regions (DRA, non-DRA, proximate to DRA). The only feature distinctly unique to the DRA ommatidia was the smaller dimension of crystalline cones in comparison to other regions. Using our novel methodology we provide the first individual-level description of DRA ommatidial features and a comparison of how the DRA area varies with body size in bumblebees.

zoology↗

bioRxiv2021

Micrometer-resolution reconstruction and analysis of whole mouse brain vasculature by synchrotron-based phase-contrast tomographic microscopy

Nervous tissue metabolism is mainly supported by the dense thread of blood vessels which mainly provides fast supplies of oxygen and glucose. Recently, the supplying role of the brain vascular system has been examined in major neurological conditions such as the Alzheimers and Parkinsons diseases. However, to date, fast and reliable methods for the fine level microstructural extraction of whole brain vascular systems are still unavailable. We present a methodological framework suitable for reconstruction of the whole mouse brain cerebral microvasculature by X-ray tomography with the unprecedented pixel size of 0.65 m. Our measurements suggest that the resolving power of the technique is better than in many previous studies, and therefore it allows for a refinement of current measurements of blood vessel properties. Relevant insights emerged from analyses characterizing the regional morphology and topology of blood vessels. Specifically, vascular diameter and density appeared non-homogeneously distributed among the brain regions suggesting preferential sites for high-demanding metabolic requirements. Also, topological features such as the vessel branching points were non-uniformly distributed among the brain districts indicating that specific architectural schemes are required to serve the distinct functional specialization of the nervous tissue. In conclusion, here we propose a combination of experimental and computational method for efficient and fast investigations of the vascular system of entire organs with submicrometric precision.

neuroscience↗

bioRxiv2020

Hierarchical imaging and computational analysis of three-dimensional vascular network architecture in the entire postnatal and adult mouse brain

The formation of new blood vessels and the establishment of vascular networks are crucial during brain development, in the adult healthy brain, as well as in various diseases of the central nervous system (CNS). Here, we describe a method that enables hierarchical imaging and computational analysis of vascular networks in postnatal- and adult mouse brains. Resin-based vascular corrosion casting, scanning electron microscopy, synchrotron radiation and desktop {micro}CT imaging, and computational network analysis are used. Combining these methods enables detailed visualization and quantification of the three-dimensional (3D) brain vasculature. Network features such as vascular volume fraction, branch point density, vessel diameter, - length, -tortuosity, and -directionality as well as extravascular distance can be obtained at any developmental stage from the early postnatal to the adult brain. Our method allows characterizing brain vascular networks separately for capillaries and non-capillaries. The entire protocol, from mouse perfusion to vessel network analysis, takes approximately 10 days. Online summaryThis protocol uses vascular corrosion casting, hierarchical synchrotron radiation {micro}CT imaging, and computational image analysis to assess the three-dimensional vascular network architecture.

neuroscience↗