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At least 19 recordsLinked to original sources
PubMed1979

Adenine cycle in hepatopancreocytes of Helix pomatia (Gastropoda).

Intact hepatopancreocytes were obtained from hibernating or active purinotelic snails, H. pomatia (Gastropoda). When incubated with [14C]glycine or [14C]formate, they synthesized de novo purine compounds, including also adenylates, adenosine and adenine. Hepatopancreocytes resynthesized also adenylates and other purine compounds from [3H]adenine or from [3H]adenosine split by the H. pomatia cell enzyme to adenine; the resynthesis of ADP+ATP was proportional to adenine concentration. Thus all reactions of the postulated adenine cycle: AMP leads to adenosine leads to adenine leads to AMP occur in the intact hepatopancreocytes; this cycle could probably be responsible for maintenance of the high level of adenylates during winter sleep.

Adenine↗
PubMed2025

De novo assembly of transcriptomes of six Hua species (Semisulcospiridae, Cerithioidea, Gastropoda).

Species in Semisulcospiridae are important in freshwater ecology and have great research value, yet their genomic resources remain very limited. Here, we present de novo assembled transcriptomes from six species of Hua in Semisulcospiridae, including Hua textrix (Heude, 1888), H. yangi L.-N. Du, J.-X. Yang & Chen, 2023, H. wujiangensis L.-N. Du, J.-X. Yang & Chen, 2023, and three undescribed species. Assembly was performed using Trinity, resulting in average contig lengths ranging from 716.6 to 883.3 bp and transcript numbers ranging from 147,147 to 268,741. Benchmarking Universal Single-Copy Ortholog (BUSCO) analysis was used to assess the transcriptome completeness. The functional annotation of transcripts for each species had over 18,000 BLAST hits, 17,000 GO terms, 15,000 KEGG pathways, 8,000 Pfam accessions, and 140 COG functional categories. This study provides valuable transcriptomic resources for the six Hua species, which can be used for various research of Semisulcospiridae, including biodiversity, phylogeny, and comparative genomics.

Transcriptome↗
PubMed2025

Genome Report: De novo genome assembly of the greater Bermuda land snail, Poecilozonites bermudensis (Mollusca: Gastropoda), confirms ancestral genome duplication.

Poecilozonites bermudensis, the greater Bermuda land snail, is a critically endangered species and one of only two extant members in its genus. These snails are one of Bermuda's few endemic animal clades and their rich fossil record was the basis for the punctuated equilibria model of speciation. Once thought extinct, recent conservation efforts have focused on the recovery of the species, yet no genomic information or other molecular sequences have been available to inform these initiatives. We present a high-quality, annotated genome for P. bermudensis generated using PacBio long read and Omni-C short read sequencing. The resulting assembly is approximately 1.36 Gb with a scaffold N50 of 44.t Mb and 31 chromosome-length scaffolds. Nearly 43 percent of the genome was identified as repeat content. This assembly will serve as a resource for the conservation and study of P. bermudensis, and its only close extant and also critically endangered relative, P. circumfirmatus. Additionally, this genome adds to the growing body of data needed for a more complete understanding of gastropod evolution and for evolutionary processes in general.

Annotation↗
PubMed2026

DNA Extraction Optimisation for Minute Land Snails of Vertigo Müller, 1773 (Gastropoda: Vertiginidae): A Comparative Evaluation of Six Methods, Including a Non-Destructive Shell-Preserving Protocol.

No systematic comparison of DNA extraction strategies exists for minute Vertiginidae (shell height <&#x2009;3&#x2009;mm), a group posing a dual analytical challenge: extremely low tissue input and co-purified PCR-inhibitory mucus. For legally protected species, an additional requirement to preserve the shell voucher further constrains available protocols. Using Vertigo antivertigo as the model species, we compared six approaches applied to specimens preserved in 96% ethanol (n&#x2009;=&#x2009;10 per method): two HotSHOT alkaline-lysis protocols (destructive and non-destructive shell-preserving variants), a modified CTAB protocol supplemented with PVP-40 and DTT, and three commercial silica-column kits (GeneJET Genomic, DNeasy Blood & Tissue, QIAamp DNA Micro). DNA yields were quantified by QuantiFluor fluorometry, and PCR performance was subsequently assessed across four loci (COI barcode, COI mini-barcode, ITS1, ITS2). DNeasy Blood & Tissue produced the highest fluorometric concentrations; QIAamp DNA Micro and CTAB&#x2009;+&#x2009;PVP-40 gave intermediate values. The shell-preserving HotSHOT variant yielded lower concentrations but improved A260/230 ratios. BSA and trehalose supplementation increased PCR success in inhibition-prone HotSHOT extracts from 70% to 100%. ITS1 Sanger sequencing of three Vertigo species listed in Annex II of the EU Habitats Directive, all extracted with the shell-preserving protocol, confirmed species-level identification (99.8%-100% BLASTn identity; mean Phred Q&#x2009;>&#x2009;51). The shell-preserving non-destructive HotSHOT protocol yields sequenceable DNA from protected Vertiginidae while retaining the morphological voucher, making it the preferred option for conservation-genetic monitoring. The practical decision framework documented here-integrating voucher preservation, amplification robustness and per-sample cost-has broad applicability to other minute terrestrial gastropods processed in large-scale biodiversity surveys.

Habitats Directive↗
PubMed1978

Degradation of the radula in the snails Biomphalaria glabrata Say and Limnaea stagnalis L. (Gastropoda, Pulmonata).

The radula of snails is formed at the posterior end of the radular gland or pocket, and degraded at the same rate at its anterior end. Degradation is due to different secretory activities of the inferior epithelium of the radular gland. Its secretions seem to degrade enzymatically the matrix of the radular membrane and basal plates of teeth, leaving only chitin containing microfibres and degradation products. The sclerotized parts of the teeth remain unchanged, but as they are now only loosely connected with the radular membrane. they are torn off easily during feeding movements. The rest of the degraded and frayed radular membrane and the subradular membrane are also lost by abrasion during feeding. The cells of the inferior epithelium are connected with each other by septate desmosomes and an elaborate system of deep lateral interdigitation which may provide tensil strength. Extrusion of degraded cells of the inferior epithelium into the subradular membrane takes place, although the thick basal lamina forms a continuous sheath which is closely adjoined to the basal parts of the inferior epithelium. Nerve fibres containing vesicles with electron dense neurosecretory material (deduced from the diameter of 200--250 nm) are attached to this sheath or penetrate into it; they may be involved in the regulation of production and degradation processes during radula replacement. Problems of the forward transport of radula and inferior epithelium are discussed.

Animals↗
PubMed1978

Unusual aggregations of tubules associated with endoplasmic reticulum in digestive cells of Alderia modesta (Mollusca: Gastropoda: Sacoglossa).

Aggregations of cylindriform tubules closely packed in a hexagonal arrangement and associated with the rough-surfaced endoplasmic reticulum (RER) are described in cells of the digestive gland of a sacoglossan gastropod. Each tubule is approximately 61 nm in outer diameter and the central lumen is lined with a layer of finely granular material. The tubule wall is composed of approximately 22 dense subunits. Adjacent tubules are associated with a pair of indistinct granules. Membranes of the RER frequently join the aggregations. The lumen of a tubule may be continuous either with the intracisternal space of the RER or with the cytoplasmic matrix of the cell. It is suggested that the aggregations of tubules are elaborations of the endoplasmic reticulum.

Animals↗
PubMed1977

Neurosecretion in the basommatophoran snail Bulinus truncatus (Gastropoda, Pulmonata).

The neurosecretory system of the freshwater snail Bulinus truncatus was investigated. With the Alcian blue-Alcian yellow (AB/AY) staining method at least 10 different types of neurosecretory cells (NSC) were distinguished in the ganglia of the central nervous system. The differences in staining properties of the NSC - with AB/AY the cells take on different shades of green and yellow - are borne out at the ultrastructural level: the NSC types contain different types of neurosecretory elementary granules. The neurosecretory system of B. truncatus is compared to that of Lymnaea stagnalis, the species which has received the most attention among the pulmonates. It appears from the comparison that the systems of both species show many similarities, although some differences are also apparent.

Alcian Blue↗
PubMed1977

Granular cells in the connective tissue of Helix pomatia L. (gastropoda, pulmonata). Histochemistry, ultrastructure, and results of polyacrylamide electrophoretic investigations.

Granular cells (cells crowded with colourless granules staining with paraldehyde fuchsin according to Gomori-Gabe and not containing calcium) are independent cells in the connective tissue of Helix pomatia. Histochemical data suggest that the granules are rich in sulfhydryl-containing proteins, but lack biogenic monoamines. Electron microscopic investigations confirm the supposed secretory activity of the granular cells. Secretory proteins are presumed to be synthetized in the endoplasmic reticulum and condensed in the Golgi apparatus giving rise to the granules. Extrusion occurs by exocytosis. Electrophoresis of homogenates, prepared from tissues containing numerous granular cells, results in the separation and identification of a secretory protein from the granular cells. An electrophoretically homologous protein is recognized in the hemolymph, but in very small quantities. Our findings and the work of others suggest the involvement of granular cells in neuroendocrine events.

Animals↗
PubMed1979

Basal bodies in the odontoblasts of the limpet, Patella coerulea L. (Gastropoda).

The odontoblasts in the long radular gland of Patella coerulea L. are arranged in a terminal position; therefore newly formed teeth already have an upright position. The long and slender odontoblasts have only one to three lengthy and ramifying apical microvilli. Between these pinnate microvilli a fine filamentous material appears which probably corresponds to chitin microfibrils. Therefore, the pattern of chitin microfibrils seems to depend on the arrangement of odontoblasts' microvilli. For the first time, basal bodies were found in the apical part of odontoblasts which led to the assumption that the radular gland originally might have been a mucous gland, the secretion of which was transported by cilia.

Animals↗
PubMed1978

Fine structure of muscle insertions on the larval shell and operculum of the nudibranch Phestilla sibogae (Mollusca: Gastropoda) before and during metamorphosis.

In Phestilla, the attachment of the larval body to shell and operculum occurs at muscle insertion sites. Attachment zones are specialized areas of squamous epithelium wherein the cells contain structures considered to be cytoplasmic anchors. The anchors are intracellular organelles consisting of apical and basal hemidesmosomal plaques connected by bundles of tonofilaments which traverse the cells. Muscle-to-epithelium and epithelium-to-shell adhesion is probably due to an extracellular cement. At metamorphosis, both shell and operculum are lost. Electron microscopic investigation of shell and opercular attachment sites during metamorphosis has demonstrated that apical hemidesmosomes lose their integrity and tonofilament bundles pull away from the apical plasmalemma of the epithelial cells as the cells lose contact with the shell or operculum.

Animals↗
PubMed1978

Accumulation and identification of lipofuscin-like pigment in the neurons of Bulla gouldiana (Gastropoda: Opisthobranchia).

A few reports suggest that pigmented granules found in molluscan neurons accumulate with age as do lipofuscin granules in vertebrate cells; however, no reports on molluscan neurons include detailed descriptions of granule accumulation or histochemical tests to identify the pigment as lipofuscin-like. In this study light microscope observations of living ganglia from 1.7, 2.7, and 3.0 cm and larger (shell length) sized Bulla gouldiana showed an increasing accumulation of orange-red pigment in the perikaryon corresponding to increasing shell size (i.e. age). With the electron microscope similar results were obtained, and lipofuscin-like granules were seen in the nerve cell cytoplasm of veliger larvae and in all adult sized Bulla. Staining with Sudan black B, Nile blue, chrome alum hematoxylin, PAS reagents, and exposure of the neurons to u.v. light to observe subsequent autofluorescence, yielded positive results in the areas of pigmented granule accumulation. Thus, the brillant orange-red granules that accumulate with age in the peripheral cytoplasm of adult Bulla neurons, and which are probably also present in larval stages, chemically resemble the lipofuscin granules of vertebrates. Similarities and differences between molluscan pigmented granules and vertebrate lipofuscin granules, in relation to structure and mechanisms of development and accumulation, are discussed.

Animals↗