SPECIFIC FEATURES OF EMBRYONIC DEVELOPMENT OF POND SNAIL (LYMNAEA STAGNALIS L.) UNDER ANTHROPOGENIC INFLUENCE OF CHLORIDE COMPOUNDS IN WATER

The article highlights the research of embryonic development of hydrobionts under the influence of anthropogenic factors of water solutions – chlorobenzene and tetrachloroethylene. To detect the toxicity of chloride pollutants in a freshwater reservoir, representatives of benthic mollusks (big pond snail Lymnaea stagnalis L.) were used as a model organism. According to the results of research, it was found that at a concentration of 0.01 mg/l of chlorobenzene solution individual anomalies of embryonic development of the pond fish are observed, but at higher concentrations its development is delayed by 5-6 stages in comparison with the control. As an integral parameter of pond fish development, we can take indicators of the biological toxicity criterion: Hatchling and its survival over a 10-day period after leaving the egg shells. Changes in the physiological parameters of pond fish embryos begin with a chlorobenzene concentration of 0.01 mg/l; the maximum permissible concentration for tetrachloroethylene for the considered biological indicators should be considered 0.05 mg/l. It is noted that in big pond snail (Lymnaea stagnalis L.) the hatch of juveniles from egg shells is the most sensitive indicator when determining the toxicity of an aqueous solution; and less sensitive indicators are the number of eggs laid and the survival of juveniles in the first 10 days after hatching. The test object used is a large pond, which has shown a high sensitivity to contamination of the water environment with chlorinated ecotoxicants and can be recommended for a comprehensive quality assessment when biotesting freshwater waters

Dynamics of seminal fluid replenishment after mating

Seminal fluid proteins (SFPs) play vital roles for optimizing reproductive success in diverse animals. Underlining their significance, SFP production and transfer are highly plastic, e.g., depending on the presence of rivals or mating status of partners. However, surprisingly little is known about replenishing SFPs after mating. It is especially relevant in multiple mating species, as they would continuously produce and use SFPs throughout their reproductive life. Here we examined the expression pattern of SFP genes after mating in the great pond snail, Lymnaea stagnalis. Our results show that three out of the six SFP genes investigated here were up-regulated after mating, indicating that L. stagnalis replenishes seminal fluid in a protein-specific manner. In addition, we suggest that SFP replenishment is plastic depending on the mating history of female-acting snails. Our results shed light on unexplored aspects of SFP replenishment, thereby expanding the understanding of reproductive strategies in animals.

Transcriptome analysis provides genome annotation and expression profiles in the central nervous system of Lymnaea stagnalis at different ages

Background The pond snail, Lymnaea stagnalis (L. stagnalis), has served as a valuable model organism for neurobiology studies due to its simple and easily accessible central nervous system (CNS). L. stagnalis has been widely used to study neuronal networks and recently gained popularity for study of aging and neurodegenerative diseases. However, previous transcriptome studies of L. stagnalis CNS have been exclusively carried out on adult L. stagnalis only. As part of our ongoing effort studying L. stagnalis neuronal growth and connectivity at various developmental stages, we provide the first age-specific transcriptome analysis and gene annotation of young (3 months), adult (6 months), and old (18 months) L. stagnalis CNS. Results Using the above three age cohorts, our study generated 55–69 millions of 150 bp paired-end RNA sequencing reads using the Illumina NovaSeq 6000 platform. Of these reads, ~ 74% were successfully mapped to the reference genome of L. stagnalis. Our reference-based transcriptome assembly predicted 42,478 gene loci, of which 37,661 genes encode coding sequences (CDS) of at least 100 codons. In addition, we provide gene annotations using Blast2GO and functional annotations using Pfam for ~ 95% of these sequences, contributing to the largest number of annotated genes in L. stagnalis CNS so far. Moreover, among 242 previously cloned L. stagnalis genes, we were able to match ~ 87% of them in our transcriptome assembly, indicating a high percentage of gene coverage. The expressional differences for innexins, FMRFamide, and molluscan insulin peptide genes were validated by real-time qPCR. Lastly, our transcriptomic analyses revealed distinct, age-specific gene clusters, differentially expressed genes, and enriched pathways in young, adult, and old CNS. More specifically, our data show significant changes in expression of critical genes involved in transcription factors, metabolisms (e.g. cytochrome P450), extracellular matrix constituent, and signaling receptor and transduction (e.g. receptors for acetylcholine, N-Methyl-D-aspartic acid, and serotonin), as well as stress- and disease-related genes in young compared to either adult or old snails. Conclusions Together, these datasets are the largest and most updated L. stagnalis CNS transcriptomes, which will serve as a resource for future molecular studies and functional annotation of transcripts and genes in L. stagnalis.

Green Tea-Derived Catechins have Beneficial Effects on Cognition in the Pond Snail

Green tea has been used as a medicine in East Asia for thousands of years. Plant-derived compounds called flavanols, which are included in green tea, may have potentials to help maintain healthy brain function. In this chapter, we review the effects of flavanols, e.g. epicatechin (EpiC), on cognitive ability in the pond snail, Lymnaea stagnalis. In this decade, the Lukowiak’s group has tested the effects of EpiC on cognition ability in Lymnaea. In a Lymnaea model system, they showed that EpiC and EpiC-containing foods have a rapid and activity-dependent effect enhancing the formation of long-term memory (LTM) following operant conditioning of aerial respiratory behavior. In the last part of this chapter, we also introduce our study for the effects of EpiC on LTM formation in another model system in Lymnaea. This study showed that EpiC increases the persistence of LTM formed by classical conditioning of feeding behavior, and suggested that EpiC alters some electrophysiological properties of a neuron in the feeding system.

SYMPTOMS OF POISONING LYMNAEA (MOLLUSCA, GASTROPODA, LYMNAEIDAE) WITH WATER MEDIUM CHROME SULFATE

Problem. Cr (III) ions are dangerously toxic for the hydrobionts of water system of the Dnieper River basin. The ions have not been previously studied in relation to their effect on a number of pond snail species. Aim. Hence, the aim of this work is to determine the range of concentrations of Cr (III) in aquatic environment that cause each of the subsequent phases of pathological process in pond snails: poisoning by the aforementioned toxicant, and presence of the complexes of symptoms of the pathological or adaptive nature that are typical for each phase. Methods.The study was conducted in 2018 in the laboratory of zoology of invertebrates of Zhytomyr Ivan Franko State University on 344 individuals of pond snails of the species Lymnaea atra, L. callomphala and L. turricula. The toxicological experiment was performed according to the technique of V. A. Alekseyev, the rate of heartbeat by D. A. Vyskushenko, the rate of branchial respiration by V. I. Zhadin, the mean daily food intake by A. P. Sushkina, the trematode (Trematoda) infection rates and morphological examination by T. A. Ginetsinskaya. Main results. Cr (III) ions are water-soluble endogenic, highly poisonous toxicant, which locally affects the respiratory branchial epithelium and skin epithelium of pond snails. The depression, and later the termination of aerobic respiration lead to their death from asphyxia. The course of poisoning is five-phase. At 0.5 MPC Cr (III) all vital functions of pond snails are carried out at the normal level (indifference phase). At concentrations of 1-2 MPC, Cr (III) ions cause an increase in their heart rate, intensity of branchial respiration, nutrition and digestion, locomotion (muscle) activity (stimulation phase). At 3 MPC of Cr (III) ions, the depression phase of intoxication develops, with the complex of symptoms including bradycardia, a sharp weakening of respiratory and trophic functions and muscle activity, with increasing degrees of hydremia, pastosity, necrosis of the respiratory epithelium and underlying tissues, and the occurrence of bleeding and hemorrhage (depressive, sublethal and lethal phases). Conclusions. The studied species of pond snails are highly sensitive to the action of Cr (III) ions and can be suggested for use as test objects in the system of hydroecological monitoring of terrestrial waters of Ukraine.