Biology subjects

Folkow, L. P.

Publications and source records attributed to Folkow, L. P..

4 recordsLinked to original sources

bioRxiv2024

DNA metabarcoding diet analysis in ruminants is quantitative and integrates feeding over several weeks

Dietary DNA metabarcoding is an established method, especially useful for resolving the diverse diets of large mammalian herbivores (LMH). However, despite longstanding research interest on the topic, we still lack unequivocal evidence on the potential of DNA metabarcoding to reflect proportions of ingested dietary plants in LMH. One major aspect to consider is the time window during which ingested diet remains detectable in faecal samples. This parameter is currently unknown for LMH, thus potentially hindering the scope of ecological conclusions. Another unknown factor is quantitative performance, i.e. the extent to which the amount of ingested biomass can be assessed based on sequence read abundances. We assessed DNA metabarcoding quantitative performance and DNA half-life detectability for plants with different digestibilities in a controlled feeding experiment with three female Eurasian tundra reindeer (Rangifer tarandus tarandus). Reindeer were fed birch twigs (Betula pubescens) and increasing biomass of lichen (mainly Cladonia stellaris). Relative read abundance positively correlated with ingested lichen biomass, suggesting potential for deriving dietary proportions in free-ranging reindeer on natural pastures. Dietary DNA was consistently detected within a few hours upon ingestion, with a mean half-life detectability of 30 and 14 hours for birch and lichen, respectively. However, dietary DNA remained detectable in faeces for at least 26 days post-feeding, indicating that a single faecal sample can provide an unsuspectedly integrative estimate of diet in ruminants. Together, our findings provide novel empirical validation of DNA metabarcoding as a tool for diet analysis in LMH.

ecology↗

bioRxiv2023

A model for maxilloturbinate morphogenesis in seals

The nasal cavities of mammals contain the maxilloturbinate bones, which are involved in respiratory heat and humidity regulation. The maxilloturbinates of Arctic seals develop into particularly elaborate labyrinthine patterns, which are well adapted to retain heat and moisture from exhaled gas. These structures develop prenatally and continue to grow postnatally. The developmental mechanism of labyrinthine patterning is unknown. Here we report a model of maxilloturbinate pattern formation in prenatal and juvenile seals based on a simple algorithmic description and three key parameters: target turbinate porosity, characteristic ossification time scale, and typical gestation time scale. Under a small set of geometrical and physical rules, our model reproduces key features of the patterns observed in grey and harp seal turbinates, and even in the less complex monk seal turbinates. To validate our model, we measure complexity, hydraulic diameter, backbone fractal dimension, and Horton-Strahler statistics for a rigorous quantitative comparison with actual tomograms of grey and harp seal skull specimens. Our model closely replicates the structural development of seal turbinates in these respects. Labyrinthine maxilloturbinate development likely requires the ability for neighbouring bone branches to detect and avoid each other through the mechanosensing of shear stresses from amniotic fluid and air flow.

developmental biology↗

bioRxiv2023

Circadian coupling of mitochondria in a deep-diving mammal

Regulation of mitochondrial oxidative phosphorylation is essential to match energy supply to changing cellular energy demands, and to cope with periods of hypoxia. Recent work implicates the circadian molecular clock in control of mitochondrial function and hypoxia sensing. Since diving mammals experience intermittent episodes of severe hypoxia, with diel patterning in dive depth and duration, it is interesting to consider circadian - mitochondrial interaction in this group. Here we demonstrate that the hooded seal (Cystophora cristata), a deep diving Arctic pinniped, shows strong daily patterning of diving behaviour in the wild. Cultures of hooded seal skin fibroblasts exhibit robust circadian oscillation of the core clock genes per2 and arntl. In liver tissue collected from captive hooded seals, expression of arntl was some 4-fold higher in the middle of night than in the middle of the day. To explore the clock-mitochondria relationship, we measured the mitochondrial oxygen consumption in synchronized hooded seal skin fibroblasts and found a circadian variation in mitochondrial activity, with higher coupling efficiency of complex I coinciding with the trough of arntl expression. These results open the way for further studies of circadian - hypoxia interactions in pinnipeds during diving. SUMMARY STATEMENTA functional clockwork and circadian variation in mitochondrial complex I efficiency is demonstrated in skin fibroblasts from the deep diving hooded seal.

physiology↗

bioRxiv2019

Ambient temperature effects on stress-induced hyperthermia in Svalbard ptarmigan

Stress-induced hyperthermia (SIH) is commonly observed during handling in homeotherms. However, in birds, handling in cold environments typically elicits hypothermia. It is unclear whether this indicates that SIH is differently regulated in this taxon or if it is due to size, because body temperatures changes during handling in low temperature have only been measured in small birds [≤] 0.03 kg (that are more likely to suffer high heat loss when handled). We have, therefore, studied thermal responses to handling stress in the intermediate-sized (0.5-1.0 kg) Svalbard ptarmigan (Lagopus muta hyperborea) in 0{degrees}C and -20{degrees}C, in winter and spring. Handling caused elevated core body temperature, and peripheral vasoconstriction that reduced back skin temperature. Core temperature increased less and back skin temperature decreased more in -20{degrees}C than in 0{degrees}C, probably because of higher heat loss rate at the lower temperature. Responses were qualitatively consistent between seasons, despite higher body condition/insulation in winter and dramatic seasonal changes in photoperiod, possibly affecting stress responsiveness. Our study supports the notion that SIH is a general thermoregulatory reaction to acute stressors in endotherms, but also suggests that body size and thermal environment should be taken into account when evaluating this response in birds.

physiology↗