Biology subjects

Majewski, B.

Publications and source records attributed to Majewski, B..

2 recordsLinked to original sources

bioRxiv2026

Range-wide validation of reduced locomotor endurance in unisexual Ambystoma salamanders

O_LILocomotor endurance is a critical physiological trait dictating terrestrial dispersal and metapopulation connectivity, especially in amphibians. C_LIO_LIThe unisexual Ambystoma complex is an ancient, all-female polyploid lineage that reproduces via kleptogenesis. This unique reproductive mode creates an evolutionary mismatch between a conserved mitochondrial genome and divergent nuclear subgenomes that are taken from sympatric, sexual species. This provides a compelling system for testing the physiological limits of polyploidy and how subgenome composition influences phenotypes. Previous locomotor assessments of this lineage demonstrate that polyploid salamanders display reduced locomotor endurance compared to sexual species. To overcome previous limitations in geographic sampling and sample size, we conducted standardized treadmill endurance trials on a broad geographic sampling of 110 salamanders, comparing the performance of triploid unisexual biotypes (LJJ and LLJ) directly to their sexually reproducing parental species (A. jeffersonianum and A. laterale). C_LIO_LIWe found that biotype significantly dictates endurance performance. Both sexual species demonstrated significantly greater total distance traveled prior to exhaustion compared to the unisexual hybrids. But within the unisexual cohort, subgenome dosage influenced performance: LJJ individuals outperformed LLJ individuals, aligning with A. jeffersonianum demonstrating greater endurance than A. laterale. C_LIO_LIWe propose that the aerobic capacity of unisexual salamanders is limited, potentially due to mitonuclear mismatch or the biophysical constraints of increased cellular volume. This endurance deficit is likely to restrict unisexual salamanders dispersal capabilities, leaving populations uniquely vulnerable to ongoing habitat fragmentation compared to more mobile, sexual species C_LI

zoology↗

bioRxiv2023

Trinucleotide mRNA cap analog N6-benzylated at the site of posttranscriptional m6Am mark facilitates mRNA purification and confers superior translational properties in vitro and in vivo

Eukaryotic mRNAs undergo co-transcriptional 5-end modification with a 7-methylguanosine cap. In higher eukaryotes, the cap carries additional methylations, such as m6Am - a common epitranscriptomic mark unique to the mRNA 5-end. This modification is regulated by the Pcif1 methyltransferase and the FTO demethylase, but its biological function is still unknown. Here, we designed and synthesized a trinucleotide FTO-resistant N6-benzyl analog of the m6Am-cap - m7GpppBn6AmpG (termed AvantCap) and incorporated it into mRNA using T7 polymerase. mRNAs carrying Bn6Am showed several advantages over typical capped transcripts. The Bn6Am moiety was shown to act as an RP-HPLC purification handle, allowing separation of capped and uncapped RNA species, and to produce transcripts with lower dsRNA content than reference caps. In some cultured cells, Bn6Am mRNAs provided higher protein yields than mRNAs carrying Am or m6Am, although the effect was cell line-dependent. m7GpppBn6AmpG-capped mRNAs encoding reporter proteins administered intravenously to mice provided up to 6-fold higher protein outputs than reference mRNAs, while mRNAs encoding tumor antigens showed superior activity in therapeutic setting as anti-cancer vaccines. The biochemical characterization suggests several phenomena underlying the biological properties of AvantCap: (i) increased competitiveness of the mRNA 5-end for eIF4E protein by reducing its propensity for unspecific interactions, (ii) direct involvement of eIF3 in alternative translation initiation, (iii) subtle differences in mRNA impurity profiles, or a combination of these effects. AvantCapped-mRNAs bearing the Bn6Am may pave the way for more potent mRNA-based vaccines and therapeutics and serve as molecular tools to unravel the role of the m6Am in mRNA.

biochemistry↗