Biology subjects

Frisk, M.

Publications and source records attributed to Frisk, M..

3 recordsLinked to original sources

bioRxiv2024

Importance of environmental signals for proper cardiac morphological development in Atlantic salmon

The hearts of salmonids display remarkable plasticity, adapting to various environmental factors that influence cardiac function and demand. For instance, in response to cold temperature, the salmonid heart undergoes growth and remodeling to counterbalance the reduced contractile function associated with dropping temperatures. Alongside heart size, the distinct pyramidal shape of the wild salmonid heart is essential for optimal cardiac performance, yet the environmental drivers behind this optimal cardiac morphology remain to be fully understood. Intriguingly, farmed salmonids often have rounded, asymmetrical ventricles and misaligned bulbi from an early age. These deformities are noteworthy given that farmed salmon are often not exposed to natural cues, such as a gradual temperature increase and changing day lengths, during critical developmental stages. In this study, we investigated whether natural environmental conditions during early life stages are pivotal for proper cardiac morphology. Atlantic salmon were raised under simulated natural conditions (low temperature with a natural photoperiod; SIMNAT) and compared with those reared under simulated farming conditions (SIMFARM). Our findings reveal that the ventricle shape and bulbus alignment in SIMNAT fish closely resemble those of wild salmon, while functional analyses indicate significant differences between SIMNAT and SIMFARM hearts, suggesting diastolic dysfunction and higher cardiac workload in SIMFARM hearts. These findings highlight the profound influence of environmental factors such as water temperature and photoperiod on the structural development of the salmonid heart, underscoring the importance of early environmental conditions for cardiac health.

physiology↗

bioRxiv2021

Gray Matter Differentiation Between Two Subordinate Personality Traits of Extraversion: Enthusiasm and Assertiveness

Enthusiasm and assertiveness are two subordinate personality traits of extraversion. These traits reflect different aspects of extroversion and have distinct implications on mental health. Whereas enthusiasm predicts satisfaction in life and positive relationships, assertiveness predicts psychological distress and reduced social support. The neural basis of these subordinate traits is not well understood. To investigate brain regions where enthusiasm and assertiveness have diverging relationship with morphology, enthusiasm and assertiveness were regressed to gray matter volume (GMV) across the whole brain in a sample of 301 healthy individuals. A significant interaction was found between enthusiasm and assertiveness in the left angular gyrus (t(296) = 4.18, family wise error corrected, FWE p = .001 (cluster-level); Cluster size = 880 voxels). Larger GMV in this area was associated with more enthusiasm and less assertiveness. Our study emphasizes the value of separating extraversion into its subordinate traits when investigating associations to neuroanatomy.

neuroscience↗

bioRxiv2018

Matched-filter based algorithm for sub- to multi-cellular classification of myocyte tubule-system

In mammalian ventricular cardiomyocytes, invaginations of the surface membrane form the transverse tubular system (T-system) which consists of transverse tubules (TTs) that align with sarcomeres and Z-lines as well as longitudinal tubules (LTs) that are present between Z-lines in some species. In many cardiac disease etiologies the T-system is perturbed, which is believed to promote spatially heterogeneous, dyssynchronous Ca2+ release and inefficient contraction. In general, T-system characterization approaches have been directed primarily at isolated cells and do not detect subcellular T-system heterogeneity. Here we present MatchedMyo, a matched-filter based algorithm for subcellular T-system characterization in isolated cardiomyocytes and millimeter-scale myocardial sections. The algorithm utilizes "filters" representative of TTs, LTs, and T-system absence. Application of the algorithm to cardiomyocytes isolated from rat disease models of myocardial infarction (MI), dilated cardiomyopathy induced via aortic banding (AB), and sham surgery confirmed and quantified heterogeneous T-system structure and remodeling. Cardiomyocytes from post-MI hearts exhibited increasing T-system disarray as proximity to the infarct increased. We found significant (p<0.05, Welchs t-test) increases in LT density within cardiomyocytes proximal to the infarct (12{+/-}3%, data reported as mean {+/-} SD, n=3) vs. sham (4{+/-}2%, n=5), but not distal to the infarct (7{+/-}1%, n=3). The algorithm also detected decreases in TTs within 5{degrees} of the myocyte minor axis for isolated AB (36{+/-}9%, n=3) and MI cardiomyocytes located intermediate (37{+/-}4%, n=3) and proximal (34{+/-}4%, n=3) to the infarct vs. sham (57{+/-}12%, n=5). Application of bootstrapping to rabbit MI tissue revealed distal sections comprised 18.9{+/-}1.0% TTs while proximal sections comprised 10.1{+/-}0.8% TTs (p<0.05), a 46.6% decrease. The matched filter approach therefore provides a robust and scalable technique for T-system characterization from isolated cells through millimeter-scale myocardial sections.

biophysics↗