Biology subjects

Michell, C.

Publications and source records attributed to Michell, C..

5 recordsLinked to original sources

bioRxiv2026

A near chromosome-scale genome assembly of the Common pine sawfly (Diprion pini, Linnaeus, 1758)

The common pine sawfly, Diprion pini, is a widespread defoliator of pine forests across Europe and Asia, with outbreaks causing substantial ecological and economic damages. However, genomic resources for this species have been limited, hindering advances in molecular ecology or pest management. Here, we present a near chromosome-level reference genome for D.pini, generated using PacBio HiFi reads, Oxford Nanopore MionION long reads, and 10x Genomics linked reads. The final assembly is organized into mostly chromosome-sized scaffolds. It spans a length of 268 Mb, comprises 81 scaffolds, and has a scaffold N50 of 18.7 Mb. BUSCO analysis (hymenoptera_odb10) indicates a high genome completeness of 97.2%. With 22,7 kb the mitochondrial genome is unusually large due to an extended non-coding control region (6,874 bp). Gene prediction identified 26,335 protein-coding genes, of which 12,769 were functionally annotated. Comparative analyses with other sawflies and Apocrita identified 2,472 proteins unique to D. pini, some of which are putatively associated with the processing of plant secondary metabolites. Notably, our genome assembly highlights that, when a closely related, high-quality reference genome is available, chromosome-scale assemblies can be generated without the need of Hi-C sequencing. The genome provides a valuable foundation for the development of improved monitoring and management strategies for D. pini outbreaks and contributes to advancing fundamental research on Hymenoptera evolution.

genomics↗

bioRxiv2024

Chromosome-level reference genome assembly for the mountain hare (Lepus timidus)

We present here a high-quality genome assembly of a male mountain hare (Lepus timidus Linnaeus), from Ilomantsi, Eastern Finland, utilizing an isolated fibroblast cell line as the source for high quality DNA and RNA. Following the previously published brown hare reference genome assembly, the mountain hare is the second Finnish pilot species for the European Reference Genome Atlas (ERGA) initiative, a collaborative effort to generate reference genomes for European biodiversity. The genome was assembled using 21x PacBio HiFi sequencing data and scaffolded using the Hi-C chromosome structure capture approach. After manual curation, the primary assembly length was 2,695,305,354 bp with N50 125,755,317 bp. The largest scaffold was 181 Mbp and the scaffold N50 127 Mbp, contributing to a primary assembly consisting of 85 scaffolds and an alternate assembly with 109 scaffolds. The scaffolds include 23 autosomes, numbered according to their size, as well as X and Y chromosomes, matching the known karyotype. Telomeric regions were present on at least one end of 19 of the chromosomes. The genome has a high degree of completeness based on the BUSCO score (mammalia_odb10 database), Complete: 95.1 % [Single copy: 92.3 %, Duplicated: 2.7 %], Fragmented 0.8 %, and Missing 4.1 %. The mitochondrial genome of the cell line was sequenced and assembled separately. The assembly meets the Earth BioGenome Project criteria for a reference-standard genome assembly. Compared to the previous pseudo-reference genome assembly of L. timidus ssp. hibernicus Bell, assembled using the rabbit genome, this new reference genome represents the nominate subspecies and the species-specific chromosomal conformation. The published genome assembly will provide a solid foundation for future genomic research on Lagomorpha, including the insights into the genomic basis of adaptations to snowy and cold environments. Furthermore, it opens opportunities for experimental analysis of mountain hare gene functions.

genomics↗

bioRxiv2024

A species difference in glycerol-3-phosphate metabolism reveals metabolic adaptations in hares

The temperate climate adapted brown hare (Lepus europaeus) and the cold-adapted mountain hare (Lepus timidus) are evolutionarily closely related and interfertile. Still, their cultured skin fibroblasts show clear differences in the expression of genes related to basic cellular metabolism. To study this further, we utilized targeted metabolomics analysis, metabolite tracing, and high-resolution respirometry, and identified significant differences in metabolic pathways associated with adaptive thermogenesis, including a higher rate of glycerol 3-phosphate (G3P) production in the mountain hare. We therefore investigated mitochondrial heat production and its dependence on G3P in the two hare species. The mountain hare maintained lower mitochondrial temperature and had weaker thermal change following OXPHOS inhibition. Manipulating mitochondrial glycerol 3-phosphate dehydrogenase (GPD2) levels demonstrated its role in mitochondrial thermogenesis and revealed species-specific function in maintaining mitochondrial membrane potential. This study unveils previously undocumented and unexpected species differences in the mitochondrial properties of fibroblasts that could indicate differences in metabolic adaptability. These findings also demonstrate the utility of cell culture models in assessing trait differences between species and their evolutionary significance, contributing to a deeper understanding of metabolic adaptation in animals and underscoring the potential of in vitro approaches for eco-physiological studies.

molecular biology↗

bioRxiv2023

High quality genome of the Mountain hare (Lepus timidus) with new chromosome level scaffolding

We present here a high-quality genome assembly of the brown hare (Lepus europaeus Pallas), based on a fibroblast cell line of a male specimen from Liperi, Eastern Finland. This brown hare genome represents the first Finnish contribution to the European Reference Genome Atlas pilot effort to generate reference genomes for European biodiversity. The genome was assembled using 25X PacBio HiFi sequencing data and scaffolded utilizing a Hi-C chromosome structure capture approach. After manual curation, the assembled genome length was 2,930,972,003 bp with N50 scaffold of 125.8 Mb. 93.16% of the assembly could be assigned to 25 identified chromosomes (23 autosomes plus X and Y), matching the published karyotype. The chromosomes were numbered according to size. The genome has a high degree of completeness based on the BUSCO score (mammalia_odb10 database), Complete: 96.1% [Single copy: 93.1%, Duplicated: 3.0%], Fragmented 0.8%, and Missing 2.9%. The mitochondrial genome of the cell line was sequenced and assembled separately. The final annotated genome has 30,833 genes of which 21,467 code for a polypeptide. The brown hare genome is particularly interesting as this species readily hybridizes with the mountain hare (Lepus timidus L.) at the species contact zone in northern Eurasia, producing fertile offspring and resulting in gene flow between the two species. In addition to providing a useful comparison for population studies, the genome can offer insight into the chromosomal evolution among Glires in general and Lagomorpha in particular. The chromosomal assembly of the genome also demonstrates that the cell line has not acquired karyotypic changes during culture.

genomics↗

bioRxiv2021

The type and source of reactive oxygen species influences the outcome of oxidative stress in cultured cells

Oxidative stress can be modeled using various different experimental approaches, such as exposing the cells or organisms to oxidative chemicals. However, the actual effects of these chemicals, outside of the immediate measured effect, have attracted relatively little attention. We show here that three commonly used oxidants, menadione, potassium bromate and hydrogen peroxide, while known to function differently, also elicit different types of responses in cultured cells. While cells response to menadione and bromate exposure mainly by an integrated stress response, hydrogen peroxide has more indirect effects. Primary oxidative stress does not induce DNA repair or antioxidant defense mechanisms. However, cells with previous experience of oxidative stress show adaptive changes when the stress is renewed. Our results urge caution when comparing studies using different sources of oxidative stress or generalizing the findings of these studies to different tissue or oxidant types.

cell biology↗