Expression pattern of arenicins—the antimicrobial peptides of polychaete Arenicola marina

Immune responses of invertebrate animals are mediated through innate mechanisms, among which production of antimicrobial peptides play an important role. Although evolutionary Polychaetes represent an interesting group closely related to a putative common ancestor of other coelomates, their immune mechanisms still remain scarcely investigated. Previously our group has identified arenicins - new antimicrobial peptides of the lugworm Arenicola marina, since then these peptides were thoroughly characterized in terms of their structure and inhibitory potential. In the present study we addressed the question of the physiological functions of arenicins in the lugworm body. Using molecular and immunocytochemical methods we demonstrated that arencins are expressed in the wide range of the lugworm tissues - coelomocytes, body wall, extravasal tissue and the gut. The expression of arenicins is constitutive and does not depend on stimulation of various infectious stimuli. Most intensively arenicins are produced by mature coelomocytes where they function as killing agents inside the phagolysosome. In the gut and the body wall epithelia arenicins are released from producing cells via secretion as they are found both inside the epithelial cells and in the contents of the cuticle. Collectively our study showed that arenicins are found in different body compartments responsible for providing a first line of defence against infections, which implies their important role as key components of both epithelial and systemic branches of host defence

Proteomic similarity of the Littorinid snails in the evolutionary context

Background The introduction of DNA-based molecular markers made a revolution in biological systematics. However, in cases of very recent divergence events, the neutral divergence may be too slow, and the analysis of adaptive part of the genome is more informative to reconstruct the recent evolutionary history of young species. The advantage of proteomics is its ability to reflect the biochemical machinery of life. It may help both to identify rapidly evolving genes and to interpret their functions. Methods Here we applied a comparative gel-based proteomic analysis to several species from the gastropod family Littorinidae. Proteomes were clustered to assess differences related to species, geographic location, sex and body part, using data on presence/absence of proteins in samples and data on protein occurrence frequency in samples of different species. Cluster support was assessed using multiscale bootstrap resampling and the stability of clustering—using cluster-wise index of cluster stability. Taxon-specific protein markers were derived using IndVal method. Proteomic trees were compared to consensus phylogenetic tree (based on neutral genetic markers) using estimates of the Robinson–Foulds distance, the Fowlkes–Mallows index and cophenetic correlation. Results Overall, the DNA-based phylogenetic tree and the proteomic similarity tree had consistent topologies. Further, we observed some interesting deviations of the proteomic littorinid tree from the neutral expectations. (1) There were signs of molecular parallelism in two Littoraria species that phylogenetically are quite distant, but live in similar habitats. (2) Proteome divergence was unexpectedly high between very closely related Littorina fabalis and L. obtusata, possibly reflecting their ecology-driven divergence. (3) Conservative house-keeping proteins were usually identified as markers for cryptic species groups (“saxatilis” and “obtusata” groups in the Littorina genus) and for genera (Littoraria and Echinolittorina species pairs), while metabolic enzymes and stress-related proteins (both potentially adaptively important) were often identified as markers supporting species branches. (4) In all five Littorina species British populations were separated from the European mainland populations, possibly reflecting their recent phylogeographic history. Altogether our study shows that proteomic data, when interpreted in the context of DNA-based phylogeny, can bring additional information on the evolutionary history of species

Data on RNA-seq analysis of the oviducts of five closely related species genus <i>Littorina</i> (Mollusca, Caenogastropoda): <i>L. saxatilis, L. arcana, L. compressa, L. obtusata, L. fabalis</i>.

In the evolution of invertebrates, the transition from egg-layers to brooders occurred many times. However, the molecular mechanisms underlying this transition are still not well understood. Recently diverged species genus Littorina (Mollusca, Gastropoda, Caenogastropoda, Littorinimorpha): Littorina saxatilis, L. arcana, L. compressa, L. obtusata and L. fabalis might be a fruitful model for elucidation of these mechanisms. All five species sympatrically inhabit an intertidal zone. Only L. saxatilis is ovoviviparous while the other four species form clutches. Although in L. saxatilis jelly gland of the pallial oviduct function as a brood pouch, it is not deeply modified at the morphological level in comparison to egg-laying relatives. Comparative analysis of transcriptomic profiles of the pallial oviducts of these closely related species might help to uncover the molecular mechanisms of the egg-laying to brooding transition. Unraveling of the mechanisms underlying this transition in L. saxatilis is important not only in aspects of reproduction biology and strategy, but also in a broader view as an example of relatively fast evolutionary transformations. We generated an RNA-seq dataset (224 104 446 clean reads) for oviducts of five species genus Littorina. Libraries of all five species were sequenced using Illumina HiSeq 2500; additional reads for L. arcana were obtained using Illumina NovaSeq 6000. Transcriptomic profiles were analyzed in pooled samples (of three individuals) with two biological replicates for each species (each biological replicate was prepared and sequenced as a separate library). The transcriptome was assembled de novo and annotated with five assembles corresponding to each species. The raw data were uploaded to the SRA database, the BioProject IDs are PRJNA662103 ("obtusata" group) and PRJNA707549 ("saxatilis" group)

Microhabitat distribution in sympatric populations of closely related species of the genus Littorina (Neritrema) in two sites in the Norwegian and Barents Sea

This dataset contains microhabitat distribution data

Metabolomes in sympatric populations of closely related species of the genus Littorina (Neritrema) in two sites in the Norwegian and Barents Sea

This zip file contains metabolomic data from gas chromatography mass-spectrometry analysis. Metabolites identification was done using fragmented spectra NIST (National Institute of Standards and Technology) database and standard chromatograms of single amino acids, monosaccharides, fatty acids manually and their mixtures

Microhabitat distribution, shell shape, and metabolomes in sympatric populations of closely related species of the genus Littorina (Neritrema) in two sites in the Norwegian and Barents Sea

This study is devoted to microevolutionary processes in populations of marine snails of subgenus Neritrema (Gastropoda, Littorinidae). We analyzed the microhabitat distribution of 5 cryptic species of molluscs (Littorina saxatilis (Olivi, 1792); Littorina arcana Hannaford Ellis, 1978; Littorina compressa Jeffreys, 1865; Littorina obtusata (Linnaeus, 1758); Littorina fabalis (Turton, 1825)) within the intertidal zone and potentially related morphological and physiological characteristics. The data was collected at two geographic locations (Saltstraumen, Norwegian Sea, 66°58'10.2"N 13°58'26.5"E, collection dates 29.06-5.07.2019; Varangerfjord, Barents Sea, 70°04'03.9"N 29°58'40.1"E, collection dates 09.07-12.07.2019). Additional information may be found in the mentioned paper

Shell morphometry in sympatric populations of closely related species of the genus Littorina (Neritrema) in two sites in the Norwegian and Barents Sea

Folder Morphometry contains geometric morphometric data. The shell shape was described by 11 landmarks and 56 semilandmarks. In total, the analysis included: 126 individuals of L. saxatilis (50-141 mm), 32 individuals of L. arcana (81-130 mm), 47 individuals of L. compressa (61-113 mm), 128 individuals of L. obtusata (55-167 mm) and 41 individuals of L. fabalis (50-147 mm)

Species-Specific Proteins in the Oviducts of Snail Sibling Species: Proteotranscriptomic Study of Littorina fabalis and L. obtusata

SIMPLE SUMMARY: Genitalia and reproduction-associated proteins are often species-specific and might evolve rapidly. The situation in which the morphology of the reproductive system is the only difference between two or several closely related species has been reported on multiple occasions. Nevertheless, the reasons for such rapid divergence of the reproductive system is still poorly investigated. To shed some light on the issue, we performed a transcriptomic and proteomic comparison of pallial oviducts from the two sibling species of gastropods Littorina obtusata and L. fabalis. The main identified differences were associated with three functional groups of genes: transposable elements, which enhance genome variation and promote the evolution of new genes, receptor proteins potentially involved in friend or foe recognition, and various enzymes. We hypothesize that these functional groups reflect both the mechanism (transposable elements) and the directions (friend or foe recognition and reproductive physiology) of the rapid evolution of the reproductive system. ABSTRACT: Genus Littorina subgenus Neritrema (Mollusca, Caenogastropoda) includes the “obtusata” group of closely related species (Littorina obtusata and L. fabalis). The anatomy of the adult reproductive system (pallial oviduct) is the only reliable feature used for species identification in females of these species. Reproductive system anatomy and reproduction-associated proteins often diverge between sibling species. Despite being of high evolutionary interest, the molecular basis of this divergence remains poorly understood. We performed proteotranscriptomic comparison of oviducts of L. obtusata and L. fabalis by RNA-seq on Illumina HiSeq 2500 and two-dimensional protein electrophoresis (2D DIGE) with MS/MS identification of the species-specific proteins. The interspecies differences in the oviduct were associated with (1) metabolic proteins reflecting overall physiological differences between L. obtusata and L. fabalis, (2) receptor proteins, and (3) transcripts related to transposable elements (TEs). Various receptors identified may recognize a wide variety of ligands from pathogen-associated molecular patterns to specific carbohydrates on the sperm surface. Therefore, these may participate in immune defense as well as in sperm storage and regulation. Species-specificity of multiple TE sequences (coding for reverse transcriptase and ribonuclease H) may indicate the important role of these genomic elements in the Littorina species divergence, which has not been reported previously