Biology subjects

Schneider, R. F.

Publications and source records attributed to Schneider, R. F..

3 recordsLinked to original sources

bioRxiv2024

Conditional protein splicing of the Mycobacterium tuberculosis RecA intein in its native host

Abstract/summaryThe recA gene, encoding Recombinase A (RecA) is one of three Mycobacterium tuberculosis (Mtb) genes encoding an in-frame intervening protein sequence (intein) that must splice out of precursor host protein to produce functional protein. Ongoing debate about whether inteins function solely as selfish genetic elements or benefit their host cells requires understanding of interplay between inteins and their hosts. We measured environmental effects on native RecA intein splicing within Mtb using a combination of western blots and promoter reporter assays. RecA splicing was stimulated in bacteria exposed to DNA damaging agents or by treatment with copper in hypoxic, but not normoxic, conditions. Spliced RecA was processed by the Mtb proteasome, while free intein was degraded efficiently by other unknown mechanisms. Unspliced precursor protein was not observed within Mtb despite its accumulation during ectopic expression of Mtb recA within E. coli. Surprisingly, Mtb produced free N-extein in some conditions, and ectopic expression of Mtb N-extein activated LexA in E. coli. These results demonstrate that the bacterial environment greatly impacts RecA splicing in Mtb, underscoring the importance of studying intein splicing in native host environments and raising the exciting possibility of intein splicing as a novel regulatory mechanism in Mtb. Significance StatementGene regulation and DNA repair are critical to the success of Mycobacterium tuberculosis, a major bacterial pathogen. The present study found significant interplay between the Mtb host environment and splicing behavior of an integrative intein element within the Mtb RecA protein, which is involved in DNA repair. These findings challenge the concept of inteins as strictly selfish genetic elements by showing that activity of the RecA intein in Mtb is finely tuned to its host and raising the possibility that intein exaptation provides Mtb with additional ways to selectively modulate RecA function.

microbiology↗

bioRxiv2024

Parent-specific transgenerational immune priming enhances offspring defense - unless heat-stress negates it all

Trans-generational immune priming (TGIP) adjusts offspring immune responses based on parental immunological experiences - a form of trans-generational plasticity predicted to be adaptive when parent-offspring environmental conditions match. In contrast, mis-matches between environmental conditions negate those advantages, rendering TGIP costly when mismatched immunological offspring phenotypes are induced. Particularly maternal TGIP was thought to shape offspring immunological preparedness: mothers eggs contain more substance than sperm and, in viviparous species, pregnancy provides additional avenues for immune priming of developing offspring. The syngnathids (pipefishes and seahorses) unique male pregnancy provides an unusual perspective to the ecological relevance of TGIP in a system where egg production and pregnancy occur in different sexes. We simulated parental bacteria exposure in broad nosed pipefish, Syngnathus typhle, through vaccinations with heat-killed Vibrio aestuarianus before mating the fish to each other or control individuals. Resulting offspring were raised, and some exposed to V. aestuarianus, in a control or heat-stress environment, after which transcriptome and microbiome compositions were investigated. Transcriptomic TGIP effects were only observed in Vibrio-exposed offspring at control temperatures, arguing for low costs of TGIP in non-matching environments. Transcriptomic phenotypes elicited by maternal and paternal TGIP had only limited overlap and were not additive. Both transcriptomic responses were significantly associated to immune functions, and specifically the paternal response to the innate immune branch. TGIP of both parents reduced the relative abundance of the experimental Vibrio in exposed offspring, showcasing its ecological effectiveness. Despite its significance in matching biotic environments, no TGIP-associated phenotypes were observed for heat-treated offspring. Heat-spikes caused by climate change thus threaten TGIP benefits, potentially increasing susceptibility to emerging marine diseases. This highlights the urgent need to understand how animals will cope with climate-induced changes in microbial assemblages by illustrating the importance - and limits - of TGIP in mitigating the impacts of environmental stressors on offspring vulnerability.

evolutionary biology↗

bioRxiv2022

A comparative analysis of the ontogeny of syngnathids (pipefishes & seahorses) reveals how heterochrony contributed to their diversification

BackgroundSyngnathids are a highly derived and diverse fish clade comprising the pipefishes, pipe-horses and seahorses. They are characterized by a plethora of iconic traits that increasingly capture the attention of biologists, including geneticists, ecologists and developmental biologists. The current understanding of the origins of their derived body plan is, however, hampered by incomplete and limited descriptions of the early syngnathid ontogeny. ResultsWe provide a comprehensive description of the development of Nerophis ophidion, Syngnathus typhle, Hippocampus erectus from early cleavage stages to release from the male brooding organ and beyond, including juvenile development. We comparatively describe skeletogenesis with a particular focus on dermal bony plates, the snout-like jaw morphology, and appendages. ConclusionsThis most comprehensive and detailed account of syngnathid development to date suggests that convergent phenotypes (e.g. reduction and loss of the caudal fins), likely arose by distinct ontogenetic means in pipefish and seahorses. Comparison of the ontogenetic trajectories of S. typhle and H. erectus provides indications that characteristic features of the seahorse body plan result from developmental truncation. Altogether this work provides a valuable resource and framework for future research to understand the evolution of the outlandish syngnathid morphology from a developmental perspective. Bullet pointsO_LISyngnathids (pipefish, pipe-horses and seahorses) are a highly derived and diverse fish taxon and many of their most iconic traits - and these traits variation across species - develop during their early ontogeny. C_LIO_LIThis study provides a detailed description and staging table of the entire pre-release development (and beyond) of three distinct syngnathids (two phylogenetically distinct pipefishes and a seahorse) with a focus on the skeletal elements forming the cranium, axial skeleton, appendages and the plate armor. C_LIO_LIThe data provided in this study suggests that developmental heterochrony, i.e. alterations in the rate and timing of developmental processes between lineages, might be a central evolutionary process shaping the morphological diversity found in syngnathids today. C_LI

developmental biology↗