Chromatin dynamics and gene expression response to heat exposure in field-conditioned versus laboratory-cultured Nematostella vectensis

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Weizman, E., Rinsky, M., Simon-Blecher, N., Lampert-Karako, S., Yaron, O., Tarrant, A. M., & Levy, O. Chromatin dynamics and gene expression response to heat exposure in field-conditioned versus laboratory-cultured Nematostella vectensis. International Journal of Molecular Sciences, 22(14), (2021): 7454, https://doi.org/10.3390/ijms22147454.Organisms’ survival is associated with the ability to respond to natural or anthropogenic environmental stressors. Frequently, these responses involve changes in gene regulation and expression, consequently altering physiology, development, or behavior. Here, we present modifications in response to heat exposure that mimics extreme summertime field conditions of lab-cultured and field-conditioned Nematostella vectensis. Using ATAC-seq and RNA-seq data, we found that field-conditioned animals had a more concentrated reaction to short-term thermal stress, expressed as enrichment of the DNA repair mechanism pathway. By contrast, lab animals had a more diffuse reaction that involved a larger number of differentially expressed genes and enriched pathways, including amino acid metabolism. Our results demonstrate that pre-conditioning affects the ability to respond efficiently to heat exposure in terms of both chromatin accessibility and gene expression and reinforces the importance of experimentally addressing ecological questions in the field

Balanus glandula: from North-West America to the west coast of South Africa

We report the occurrence of the North-East Pacific intertidal barnacle Balanus glandula in the south-western African shores of the Atlantic Ocean. In addition, an attempt is made to trace the origin of the South African population by comparing the distribution of haplotype groups of two molecular markers, cytochrome oxidase subunit I (COI) and elongation factor 1 (EF1-α). The frequency of COI haplotypes in the South African specimens was most similar to that in specimens from Bodega Marine Laboratory and of Fort Bragg in Central California. Pairwise genetic distances demonstrated that the samples from Pillar Point were also similar to the Cape Town population. The frequency of EF1-α haplotype groups from Cape Town was most similar to that of Cape Blanco, Cape Meares and Westport Jetty, and, with lower p-values, to the populations of Cape Mendocino and Heceta Head. Pairwise genetic distances demonstrated that samples from Vancouver Island, Bodega Marine Laboratory and Heceta Head were also similar to the Cape Town population. Results indicate that the population of B. glandula from South Africa is most similar to the population from the northern portion of the Oregonian faunal province. It is possible that this is the origin of the South African population. As a result of this invasion, B. glandula out-competed the native African chthamalid species, Chthamalus dentatus. Thus, C. dentatus is presently very rare on the Atlantic South African shores. Keywords: Balanus glandula, COI, competition, EF1-α, haplotypes, invasion, South AfricaAfrican Journal of Marine Science 2008, 30(1): 85–9

Tidal and diel orchestration of behaviour and gene expression in an intertidal mollusc

Abstract Intertidal inhabitants are exposed to the 24-hour solar day, and the 12.4 hour rising and falling of the tides. One or both of these cycles govern intertidal organisms’ behaviour and physiology, yet little is known about the molecular clockworks of tidal rhythmicity. Here, we show that the limpet Cellana rota exhibits robust tidally rhythmic behaviour and gene expression. We assembled a de-novo transcriptome, identifying novel tidal, along with known circadian clock genes. Surprisingly, most of the putative circadian clock genes, lack a typical rhythmicity. We identified numerous tidally rhythmic genes and pathways commonly associated with the circadian clock. We show that not only is the behaviour of an intertidal organism in tune with the tides, but so too are many of its genes and pathways. These findings highlight the plasticity of biological timekeeping in nature, strengthening the growing notion that the role of ‘canonical’ circadian clock genes may be more fluid than previously thought, as exhibited in an organism which has evolved in an environment where tidal oscillations are the dominant driving force