Authors: Tamar Gutnick, Daniel S Rokhsar, Michael J Kuba...

Underlying all animal behaviors, from the simplest reflexive reactions to the more complex cognitive reasoning and social interaction, are nervous systems uniquely adapted to bodies, environments, and challenges of different animal species. Coleoid cephalopods - octopuses, squid, and cuttlefish - are widely recognized as the most behaviorally complex invertebrates and provide exciting opportunities for studying the neural control of behaviour. These unusual molluscs evolved over 400 million years ago from slow-moving armored forms to active predators of coastal and open ocean ecosystems. In this primer we will discuss how, during cephalopod evolution, the relatively simple ganglion-based molluscan nervous system has been extensively transformed to control the complex bodies and process extensive visual, tactile, and chemical sensory inputs, and summarize some recent findings about their fascinating behaviors.

Topics: Animals; Cephalopoda; Ecosystem; Mollusca; Invertebrates; Octopodiformes; Nervous System; Decapodiformes

PubMed: 37875088
DOI: 10.1016/j.cub.2023.08.094

Review

Authors: Jonathan H Schultz, Coen M Adema

Comparative immunology, studying both vertebrates and invertebrates, provided the earliest descriptions of phagocytosis as a general immune mechanism. However, the large scale of animal diversity challenges all-inclusive investigations and the field of immunology has developed by mostly emphasizing study of a few vertebrate species. In addressing the lack of comprehensive understanding of animal immunity, especially that of invertebrates, comparative immunology helps toward management of invertebrates that are food sources, agricultural pests, pathogens, or transmit diseases, and helps interpret the evolution of animal immunity. Initial studies showed that the Mollusca (second largest animal phylum), and invertebrates in general, possess innate defenses but lack the lymphocytic immune system that characterizes vertebrate immunology. Recognizing the reality of both common and taxon-specific immune features, and applying up-to-date cell and molecular research capabilities, in-depth studies of a select number of bivalve and gastropod species continue to reveal novel aspects of molluscan immunity. The genomics era heralded a new stage of comparative immunology; large-scale efforts yielded an initial set of full molluscan genome sequences that is available for analyses of full complements of immune genes and regulatory sequences. Next-generation sequencing (NGS), due to lower cost and effort required, allows individual researchers to generate large sequence datasets for growing numbers of molluscs. RNAseq provides expression profiles that enable discovery of immune genes and genome sequences reveal distribution and diversity of immune factors across molluscan phylogeny. Although computational de novo sequence assembly will benefit from continued development and automated annotation may require some experimental validation, NGS is a powerful tool for comparative immunology, especially increasing coverage of the extensive molluscan diversity. To date, immunogenomics revealed new levels of complexity of molluscan defense by indicating sequence heterogeneity in individual snails and bivalves, and members of expanded immune gene families are expressed differentially to generate pathogen-specific defense responses.

Topics: Animals; Biological Evolution; Genomics; High-Throughput Nucleotide Sequencing; Immunity, Innate; Immunogenetics; Mollusca; Phagocytosis; Phylogeny; Physiology, Comparative

PubMed: 28322934
DOI: 10.1016/j.dci.2017.03.013

Review

Authors: Fabrizio Ghiselli, André Gomes-Dos-Santos, Coen M Adema...

The first animal mitochondrial genomes to be sequenced were of several vertebrates and model organisms, and the consistency of genomic features found has led to a 'textbook description'. However, a more broad phylogenetic sampling of complete animal mitochondrial genomes has found many cases where these features do not exist, and the phylum Mollusca is especially replete with these exceptions. The characterization of full mollusc mitogenomes required considerable effort involving challenging molecular biology, but has created an enormous catalogue of surprising deviations from that textbook description, including wide variation in size, radical genome rearrangements, gene duplications and losses, the introduction of novel genes, and a complex system of inheritance dubbed 'doubly uniparental inheritance'. Here, we review the extraordinary variation in architecture, molecular functioning and intergenerational transmission of molluscan mitochondrial genomes. Such features represent a great potential for the discovery of biological history, processes and functions that are novel for animal mitochondrial genomes. This provides a model system for studying the evolution and the manifold roles that mitochondria play in organismal physiology, and many ways that the study of mitochondrial genomes are useful for phylogeny and population biology. This article is part of the Theo Murphy meeting issue 'Molluscan genomics: broad insights and future directions for a neglected phylum'.

Topics: Animals; Gene Duplication; Gene Rearrangement; Genome, Mitochondrial; Heredity; Mollusca

PubMed: 33813887
DOI: 10.1098/rstb.2020.0159

Review

Authors: Carmel McDougall, Bernard M Degnan

Molluscan shells are externally fabricated by specialized epithelial cells on the dorsal mantle. Although a conserved set of regulatory genes appears to underlie specification of mantle progenitor cells, the genes that contribute to the formation of the mature shell are incredibly diverse. Recent comparative analyses of mantle transcriptomes and shell proteomes of gastropods and bivalves are consistent with shell diversity being underpinned by a rapidly evolving mantle secretome (suite of genes expressed in the mantle that encode secreted proteins) that is the product of (a) high rates of gene co-option into and loss from the mantle gene regulatory network, and (b) the rapid evolution of coding sequences, particular those encoding repetitive low complexity domains. Outside a few conserved genes, such as carbonic anhydrase, a so-called "biomineralization toolkit" has yet to be discovered. Despite this, a common suite of protein domains, which are often associated with the extracellular matrix and immunity, appear to have been independently and often uniquely co-opted into the mantle secretomes of different species. The evolvability of the mantle secretome provides a molecular explanation for the evolution and diversity of molluscan shells. These genomic processes are likely to underlie the evolution of other animal biominerals, including coral and echinoderm skeletons. This article is categorized under: Comparative Development and Evolution > Regulation of Organ Diversity Comparative Development and Evolution > Evolutionary Novelties.

Topics: Animal Shells; Animals; Calcium; Evolution, Molecular; Mollusca

PubMed: 29470863
DOI: 10.1002/wdev.313

Review

Authors: Erika Staudacher

Molluscs display a sophisticated N-glycan pattern on their proteins, which is, in terms of involved structural features, even more diverse than that of vertebrates. This review summarises the current knowledge of mollusc N-glycan structures, with a focus on the functional aspects of the corresponding glycoproteins. Furthermore, the potential of mollusc-derived biomolecules for medical applications is addressed, emphasising the importance of mollusc research.

Topics: Animals; Carbohydrate Sequence; Glycoproteins; Glycosylation; Mollusca; Polysaccharides

PubMed: 34944464
DOI: 10.3390/biom11121820

Review

Authors: Scott Wyer, Danyelle M Townsend, Zhiwei Ye...

Since the discovery of the kahalalide family of marine depsipeptides in 1993, considerable work has been done to develop these compounds as new and biologically distinct anti-cancer agents. Clinical trials and laboratory research have yielded a wealth of data that indicates tolerance of kahalalides in healthy cells and selective activity against diseased cells. Currently, two molecules have attracted the greates level of attention, kahalalide F (KF) and isokahalalide F (isoKF, Irvalec, PM 02734, elisidepsin). Both compounds were originally isolated from the sarcoglossan mollusk Elysia rufescens but due to distinct structural characteristics it has been hypothesized and recently shown that the ultimate origin of the molecules is microbial. The search for their true source has been a subject of considerable research in the anticipation of finding new analogs and a culturable expression system that can produce sufficient material through fermentation to be industrially relevant.

Topics: Animals; Antineoplastic Agents; Depsipeptides; Mollusca; Neoplasms

PubMed: 35149387
DOI: 10.1016/j.biopha.2022.112676

Authors: Kunpeng Qin, Shuai Jiang, Hang Xu...

Gasdermin (GSDM) is a family of proteins that execute pyroptosis in vertebrate. In invertebrate, pyroptotic GSDM was documented only in coral. Recent studies identified abundant GSDM structural homologs in Mollusca, but their functions are unclear. Herein, we report a functional GSDM from Pacific abalone Haliotis discus (HdGSDME). HdGSDME is specifically activated by abalone caspase 3 (HdCASP3) cleavage at two distinct sites, generating two active isoforms with pyroptotic and cytotoxic activities. HdGSDME possesses evolutionarily conserved residues that proved to be essential to the N-terminal pore-formation and C-terminal auto-inhibition capacities. Bacterial challenge activates the HdCASP3-HdGSDME pathway and induces pyroptosis and extracellular traps in abalone. Blockage of the HdCASP3-HdGSDME axis promotes bacterial invasion and host mortality. Collectively, this study reveals the existence of functionally conserved and yet distinct-featured GSDM in Mollusca and provides insights into the function and evolution of invertebrate GSDM.

Topics: Animals; Gasdermins; Neoplasm Proteins; Pyroptosis; Mollusca; Bacterial Infections

PubMed: 37074912
DOI: 10.1016/j.celrep.2023.112414

Authors: Jonathan Q Henry

Topics: Animals; Annelida; Bryozoa; Developmental Biology; Embryo, Nonmammalian; Mollusca; Platyhelminths

PubMed: 25690956
DOI: 10.1387/ijdb.140289jh

Authors: Gerhard Haszprunar, Andreas Wanninger

Topics: Animals; Fresh Water; Humans; Mollusca; Phylogeny; Research; Shellfish

PubMed: 22789994
DOI: 10.1016/j.cub.2012.05.039

Authors: Carmel McDougall, Felipe Aguilera, Patrick Moase...

Topics: Animals; Aquaculture; Mollusca; Nacre

PubMed: 23968917
DOI: 10.1016/j.cub.2013.05.042