snail embryo developmentsnail embryo development

Neuronal inputs and outputs of aging and longevity. But finding out more about the heritability of developmental speed is important, because changes in this speed have been linked to the evolution of new species. J Comp Physiol A Neuroethol Sens Neural Behav Physiol. The embryonic development of the fresh-water snail Biomphalaria glabrata was examined under microgravity-conditions and compared with the ground control and standard embryos, putting special . 2014;393:10923. They then compared these figures with those obtained from the snails parent (R. balthica is hermaphroditic so can have just a single parent). Treading the path towards genetic control of snail resistance to schistosome infection. Examining aggregated rotation rates of H. trivolvis embryos at each pond suggested that embryos alter their rotational activity to occupy a select range depending upon the characteristics of the pond. Depending on the temperature, embryonic development until hatch takes from 8 to 20 days (about 12 days at 26C). As embryos consume O2, a concentration gradient develops within the egg capsule which, if left undisturbed, can lead to decreased O2 levels in close proximity to the embryo (Cohen and Strathmann, 1996; Kuang et al., 2002a). By using a single laboratory-reared strain in this initial study, the confounding effects of strain differences between isolated populations are mitigated (Orr et al., 2009). Transcriptome analysis of the central nervous system of the mollusc Lymnaea stagnalis. Koene JM, Ter Maa A. Coolidge effect in pond snails: male motivation in a simultaneous hermaphrodite. masses produced by snails taken in the field and lowest in snails reared together in a common aquarium. Malacologia. Rabinowitz JS, Chan XY, Kingsley EP, Duan Y, Lambert JD. All measurements were taken 1 h apart, starting at 09:00 h (0 h). Nat Commun. Spiralian model systems. Rotational behaviour and the underlying ciliary activity stir the capsular fluid, reducing the O2 gradient and increasing O2 availability adjacent to the embryo (Strathmann and Chafee, 1984; Goldberg et al., 2008). Microscopic images have captured those early milestones in a snail's life. Davison A, Blaxter ML. Reversal of age-related learning deficiency by the vertebrate PACAP and IGF-1 in a novel in-vertebrate model of aging: the pond snail (Lymnaea stagnalis). Cell lineage studies in mollusk embryos have documented numerous variations on the lophotrochozoan theme of spiral cleavage. Takahashi H, Abe M, Kuroda R. GSK3 controls the timing and pattern of the fifth spiral cleavage at the 2-4 cell stage in Lymnaea stagnalis. Herlitze I, Marie B, Marin F, Jackson DJ. Katie Gilmour tells us how she first encountered the JEB Editorial team as a graduate student at the University of Cambridge, UK, and how she would like to have a Star Trek tricorder to monitor fish non-invasively in the field. Similarly, eutrophic ponds probably became depleted of O2 during the night, and a full circadian analysis of rotational behaviour may reveal the expected link between O2 and rotation. PLoS ONE. Alcedo J, Flatt T, Pasyukova EG. Visit exhibition stand 13/15 to pick up JEB centenary goodies, including our new 100 years of discovery T shirt, and join our Meet the JEB Editors event on Thursday 6 July at 12.30 at Platform 5 to find out more about the journal and chat to Editors including EiC Craig Franklin, Monitoring Editors Sanjay Sane, Trish Schulte and John Terblanche and the in-house News and Reviews team. Likewise, the behaviour of both species was quite stable. Measurements at the Belly River drainage were performed during August 2007 and were made at approximately 4-h intervals during daylight hours. Animal species for developmental studies Invertebrates, vol. Tascedda F, Malagoli D, Accorsi A, Rigillo G, Blom JM, Ottaviani E. Molluscs as models for translational medicine. The importance of evo-devo to an integrated understanding of molluscan biomineralisation. More recently, relevant asymmetrically expressed molluscan shell matrix proteins (SMPs) were found using proteomic and transcriptomic datasets in the left and right sides of mantle tissue [30, 31]. In addition to embryonic O2 consumption, other factors can influence O2 levels, including fouling organisms on the egg mass (Cohen and Strathmann, 1996; Przeslawski and Benkendorff, 2005) and embryonic behaviour (Hunter and Vogel, 1986; Goldberg et al., 2008). Conductivity was very high in this pond (224780.4 S cm1), approximately three times greater than the other ponds. The Rosebud pond was highly eutrophic, largely due to the high levels of bovine faecal matter contained in the run-off water that fed the pond. Their loss does not change the chirality [8]. The basic tissue phenotypes in vertebrates are epithelium and mesenchyme (Fig. Encapsulated freshwater pond snail embryos display a cilia-driven rotation behaviour that is stimulated by artificially induced hypoxia. L. stagnalis has been accepted as a standard test organism for ecotoxicological studies with an OECD guideline for a reproduction test (OECD, 2016). Google Scholar. Reversal of cleavage in a sinistral gastropod. It is widely distributed in freshwater habitats over large parts of Europe, North America and Asia except its most southern region [4]. The results suggest that embryonic rotation is controlled through a complex interplay of environmental factors, and not strictly by changes in environmental [O2]. Students may see eggs in early development and/or in late developmental stages. 2019;13:65. Ishikawa A, Shimizu K, Isowa Y, Takeuchi T, Zhao R, Kito K, Fujie M, Satoh N, Endo K. Functional shell matrix proteins tentatively identified by asymmetric snail shell morphology. 1999;16:71123. There is a Lymnaea stagnalis Sequencing Consortium web site (http://www.lymnaea.org/members.html). The egg mass was stabilized with dental wax at the lower edge of the dish. During embryonic development, both the olfactory and lens placodes share a common origin from the preplacodal ectoderm [].Over time, the spatial competence of the olfactory placode becomes restricted and specified to the most antero-lateral side of the head ectoderm [].In 1975, Cuschieri and Bannister first described the ontogeny of the mouse VNO []. Provided by the Springer Nature SharedIt content-sharing initiative. Dev Genes Evol. Research Partnership Kickstart Travel Grants, Society for Experimental Biology centenary conference, New funding schemes for junior faculty staff. Nederbragt AJ, van Loon AE, Dictus WJ. Drug inhibition experiments can provide information on the functions of target proteins. embryonic development, and growth in the pond snail, Physa gyrina (Say). Kungl Svenska Vetensk Akad Handl. Embryo rotation rate in hypoxia is [O2] dependent under laboratory conditions. For most experiments on L. stagnalis, drugs can be applied to eggs within the capsules. It is the genotype of the ovary in which the oocyte develops that determines which orientation cleavage will take. The toxicity of potassium usnate was evaluated. For most animals, the left half of the body is pretty much a mirror image of the right half, at least on the outside. The aquaria were eumoxic, which was defined as normal [O2], >4.2 mg O2 l1 water (Martens et al., 2007). snail mutants display a massive derepression of mesectodermal genes such as single-minded and rhomboid (Kasai, 1992 and Ip, 1992a). kept their gene naming of Lsdia1 and Lsdia2, which correspond to Davison et al.s Ldia2 and Ldia1, respectively, because Davison et al.s published gene and inferred protein sequences are different in key aspects from Lsdia1/2 [26, 27]. It is surprising that O2 only weakly affected embryonic rotation in natural ponds because O2 fluctuations pose a challenge for encapsulated embryos (Strathmann and Strathmann, 1995; Fernandez et al., 2006). Each egg, dark/intense yellow in color, measures about 100m in diameter, and is contained in an oval-shaped capsule (Fig. 4a). Biallelic frameshift mutations introduced into the gene produced sinistrally coiled offspring generation after generation in the otherwise totally dextral genetic background. Previous laboratory studies found that both pH and conductivity within a normal healthy environmental range have very little effect on rotational behaviour (Kuang, 2002). The eggs of a single mass vary from spherical to ovoid in shape. The Snail family of transcriptional repressors regulates cell movements during embryonic development and cancer progression (Hemavathy et al., 2000; Nieto, 2002). Egg mass is collected from the aquarium maintaining the adult snails, and the egg capsules are isolated by rolling the egg mass on a sheet of filter paper to remove the surrounding jelly. Correspondence to Tsai HJ, Lai CH, Yang HS. The opposing actions of twist and snail can best be observed by examining the extent of altered mitotic domains in mutant embryos. For every Research and Review article published in Journal of Experimental Biology a native tree is planted in a UK forest. For th. Its lifespan is generally 612months in our laboratory. As temperature is an environmental variable capable of altering behavioural and physiological functions in other animal systems, we first examined the rotational response to temperature within controlled laboratory settings. Science. Transactions of . Scale bar equals 20m. 2004;14(16):14627. Water temperature varied by 2 to 4C, and pH and conductivity were 7.60.1 units and 4373.3 S cm1, respectively. The first 13 cleavage divisions of a wild type embryo are synchronous. This trait allows adaptation to oxygen-poor environments. Grande C, Patel NH. Article Scale bar 100m. Progress on this question would probably require the development of a mathematical model that assesses the relative roles of additional environmental factors. PubMed from 4-7 July in Edinburgh, UK. A schematic drawing to show the formation of micromeres from respective macromeres is shown. Ryan B. Shartau, Stephanie Harris, Evelyn C. Boychuk, Jeffrey I. Goldberg; Rotational behaviour of encapsulated pond snail embryos in diverse natural environments. Kuroda R, Abe M. Response to Formin, an opinion. BMC Neurosci. 2016;26(5):65460. 2020;108:60216. PubMed Central (A) Rotation rates were measured at room temperature (~221C), during a 60 min exposure to 10C and after returning to room temperature; black line indicates the duration of the experimental temperature. BMC Evol Biol. The species has the advantage of being a hermaphrodite and can both cross- and self-mate, which greatly facilitates genetic approaches. Boycott AE, Diver C. On the inheritance of sinistrality in Limnaea peregra. Google Scholar. The eggs are transferred to a droplet of injection buffer on the sample stage. . Nature. H. trivolvis embryos, which normally rotate at stable rates under laboratory conditions, changed their rotation behaviour in various ponds, but this could not be directly explained by the environmental variables measured. Bundles of chromosomes in snail embryos (red arrows in top panels) and cell boundaries (white arrows in middle panels) start twisting early in development for snails with right-spiraling shells (right column). Embryos of both species were viewed under a dissection microscope and staged as a percentage of intracapsular development, with stage E0 corresponding to the zygote at 0% development and stage E100 corresponding to hatching at 100% development (Goldberg and Kater, 1989; Diefenbach et al., 1998; Voronezhskaya et al., 1999). Fine mapping of the pond snail left-right asymmetry (chirality) locus using RAD-Seq and fibre-FISH. This population of H. trivolvis probably lived in freshwater streams, ponds and lakes similar to where wild H. trivolvis populations are now found. 2A). 1. One . Lymnaea stagnalis serves as the intermediate host for more than one hundred species of digenetic trematodes, including the avian schistosome Trichobilharzia szidati, a causative agent of cercarial dermatitis in humans (Fig. That [O2] did not have as large an effect on rotation rates as was originally predicted may have been due to the range of O2 levels that were reached. Epithelial-mesenchymal transformation (EMT) is a major embryological mechanism for tissue remodeling that currently is attracting considerable attention to the role of the mesenchymal cell in the embryo. Google Scholar. In addition to these data on chick embryos and the studies in Xenopus that show the role of Slug in both specification and migration 9,14,45, the expression patterns of Slug and Snail in other . Thus, the A concentration can be kept low and well controlled for each individual animal. Concentrations of O2 remained high throughout the season observed, averaging around 10 mg O2 l1 water with minimal daily fluctuations (Fig. Totani Y, Aonuma H, Oike A, Watanabe T, Hatakeyama D, Sakakibara M, Lukowiak K, Ito E. Monoamines, insulin and the roles they play in associative learning in pond snails. All embryos used in this study were of embryonic stage E20E30 for H. trivolvis and E35E40 for L. stagnalis. Standard outside capsule protocols, on the other hand, do not give any localization for -actin, -tubulin, Lsdia1 nor Lsdia2 genes [15, 25]. This change was reversible, as embryonic rotation recovered to pre-treatment levels in all cases following a return to room temperature (22C). In recent years, several works addressing the environmental risk assessment of chemicals (tributyltin and coal tar) and micro-plastics, were published also using this snail [60,61,62]. Adult snails and lifecycle. To accomplish this, O2 concentration ([O2]), temperature and other environmental factors were measured at five different ponds in Southern Alberta and related to the rotational behaviour displayed by snail embryos at these sites. Front Physiol. However, O2 reductions due to temperature and consumption can easily be offset by the production of O2 by photosynthesis, as some species of algae can produce over 40 mg O2 g1 tissue h1, which may also explain why some ponds become supersaturated with O2 (King and Schramm, 1976). T he news on 14 June that scientists had made "synthetic human embryos" caused widespread surprise and alarm. Genesis. 1c. Their diet consisted of romaine lettuce and trout pellets (NU-WAY: United Feeds, Okotoks, AB, Canada). Castillo MG, Humphries JE, Mouro MM, Marquez J, Gonzalez A, Montelongo CE. Kuroda, R., Abe, M. The pond snail Lymnaea stagnalis. Dev Comp Immunol. Research Partnership Kickstart Travel Grants. Development. PLoS Negl Trop Dis. Dalesman S, Karnik V, Lukowiak K. Sensory mediation of memory blocking stressors in the pond snail Lymnaea stagnalis. Cyclic AMP-responsive element binding protein. All measurements were taken 1 h apart, starting at 09:00 h (0 h). To examine rotational responses to [O2], egg masses were exposed to various O2 levels ranging from eumoxia to anoxia. The rotational behaviour of laboratory-reared Lymnaea stagnalis provided confirmation that embryos of other encapsulated pulmonates exhibit a similar rotational response in natural environments. Practice is needed for successful microinjection (Fig. PubMed The two other ponds examined, Sibbald Flats and Belly River Drainage, also exhibited fluctuations in water temperature and [O2] with negligible changes in pH and conductivity. Movies of embryonic behaviour were captured and analyzed using the time-lapse function of Northern Eclipse imaging software (Northern Eclipse 6.0, Empix Inc., Mississauga, ON, Canada). The breeding process of snails has some unique features when compared to other land animals. 3. Statistics should be checked on the ratio of dead/tested embryos in comparison with control experiments to avoid focusing on a rarely observed phenotype. Biomphalaria glabrata immunity: post-genome advances. Q. Rev. The difference between these two points represents an approximate sevenfold increase (Fig. (B) Embryo rotation rates of H. trivolvis (N=510). Biophys. 3B), and were significantly affected by both pond pH and water temperature (Table 2). Multiple mating suppresses fecundity in the hermaphrodite freshwater snail Lymnaea stagnalis: a laboratory study. The snail bodies are yellowish grey. Consistent with this view is that ENC1 is thought to be a homologue of the para-ampullary neurons of the apical organ, the neural structure that controls locomotion in veliger larvae (Voronezhskaya et al., 1999). CRISPR/Cas9 genome editing allows for a more targeted analysis of gene function [74]. 2020;147(1):181081. In Lymnaea, the forward genetics approach has been used to identify candidate genes including the gene determining leftright shell coiling [15,16,17,18,19, 21] (see Chiromorphogenesis during development section). Crepidula fornicata. Mechanisms underlying the leftright determination process have been intensively investigated in both vertebrates and invertebrates [11,12,13,14,15, and references therein]. 2B). Snail development from embryo to hatching New Scientist 267K subscribers Subscribe 29K views 9 years ago This time lapse captures early milestones in a snail's life in minute detail, revealing. 2002;22(11):RC227. Neither pH (6.50.1) nor conductivity (3136.6 S cm1) underwent obvious daily changes, but over the summer conductivity and pH gradually increased. 1). CRISPR/Cas9-mediated genome modification in the mollusc. J Neurosci. Previous studies have suggested that the mixing effect of this behaviour causes enhanced oxygen delivery to embryos within their egg capsules. L. stagnalis prefers living in waters that flow slowly or in stagnant water bodies and occupies shallow pond margins with dense vegetation where it usually feeds on algae or decaying plants. Embryonic and tissue-specific regulation of myostatin-1 and -2 gene expression in zebrafish. Appropriate controls must be carried out to avoid misleading conclusions caused by artifacts. Egg capsules are cultured in 1.5HF (Holtfretters) solution [16]. In vitro synaptogenesis between the somata of identified Lymnaea neurons requires protein synthesis but not extrinsic growth factors or substrate adhesion molecules. 2009;74:2817. Names and locations of ponds used for field studies. Cold Spring Harb Symp Quant Biol. 2016;196(2):6774. Our studies of rotational behaviour over two decades have consistently revealed a paucity of variation between egg masses and thus form the basis of our current statistical approach. For example, caution should be exercised with within-capsule fixing procedures (in which the embryo is not removed from its capsule), with which remarkable asymmetric localization for the transcripts of housekeeping genes, -actin and -tubulin, was observed [26], just like the asymmetric expression of dia genes in the literature [21]. In vitro-synthesized mRNA expression is important for the understanding of molecular mechanisms during development. Adult snails are 35 and 23cm in shell length and width, respectively. No localization of Lsdia1 nor Lsdia2 mRNA was observed within a cell at the 1-cell stage, nor among blastomeres in the 2- or 4-cell stages [15, 26], although different results have been reported [21] (see Experimental approaches below for detail). 2018;3(3):E86. 4e shows a juvenile snail (encircled) cultured inside a capillary. 2008;18(5):3316. 2011;214:252833. Insights from a molluscan transcriptome. Grande C, Patel NH. Egg masses were removed from the collecting dishes with a razor blade and transferred to another Petri dish (70 mm diameter) containing APW for embryonic staging. Sperm as a carrier to introduce an exogenous DNA fragment into the oocyte of Japanese abalone (Haliotis divorsicolor suportexta). For two of the events they studied attaching the foot to the interior wall of the egg, and then crawling along this surface the similarity was strong enough to be considered inherited. Mechanogenetics. Visit our virtual forest to learn more. This abrogates expression of full-length LsDia1 protein, which is normally present already at the one-cell stage of the dextral embryos. A conserved set of maternal genes? De novo sequencing and transcriptome analysis of the central nervous system of mollusc Lymnaea stagnalis by deep RNA sequencing. However, if timing is critical and a delay of drug delivery to the capsules and embryos does matter, then decapsulated eggs should be used. 2013;4(1):15. 0. All suspect snail samples were submitted for final identification. 2010;13:11619. Egg hatching. Vandenberg LN, Levin M. Far from solved: a perspective on what we know about early mechanisms of left-right asymmetry. The water temperature in the Petri dish was 1.30.2C higher at the start and 3.30.3C higher at the finish than the pond water temperature. Measurements of embryonic rotation were taken initially at room temperature, then at either 5, 10, 15, 20, 25, 30, or 35C at 10 min intervals over 1 h. Following the temperature treatments, the APW was allowed to return to room temperature and rotation was again recorded at 10 min intervals. Keywords: Kemenes G, Benjamin PR. (El) Students use hand lenses, dissecting microscopes, and compound microscopes to examine developing snail eggs. Ecotoxicology. The pond snail Helisoma trivolvis has a broad geographical range within North America, stretching from arctic Canada to Florida and generally thrives in rich, eutrophic environments (Brown, 1991). The authors thank Wic Wildering for assistance with the manuscript and Larry Linton for assistance with statistical analysis. Asymmetric expression of nodal/Pitx genes was known to regulate asymmetric location/morphology of organs in vertebrates, and the genes were found to function in this snail as well [8, 16, 23, 24]. Journal reference: Proceedings of the Royal Society B, DOI: 10.1098/rspb.2013.1479, Explore the latest news, articles and features, Record for hottest day ever recorded on Earth broken twice in a row, Efforts to mass-produce green steel are finally nearing reality. 2020;102:103464. Lymnaea stagnalis may offer to translational medicine a powerful new tool to study age-related diseases of the nervous system by identifying new molecular targets for the development of innovative therapeutic strategies, and by enabling the screening of large numbers of compounds for drug activity. The age of sexual maturity is variable from 6 weeks to 5 years, depending on species of snail. 2013;28129:606. In the total of four experiments, 39 injected embryos were cultured. CAS I. Embryonic development of dopamine-containing neurons and dopamine-dependent behaviours, Ecological modulation of environmental stress: interactions between ultraviolet radiation, epibiotic snail embryos, plants and herbivores, This site uses cookies. Temperature and O2 are believed to act as primary drivers of this behaviour, as supported by laboratory results; however, other environmental factors have large influences over this behaviour. Students may see eggs in early development and/or in late developmental stages. During embryo development, the eggs swell up to 4 mm. Embryo rotation is an energy intensive activity that is probably responsive to changes in metabolic activity, because of both the high demand on ATP production and the extensive biomechanical and energetic processes underlying ciliary beating (Goldberg et al., 2008). 2013;4:71. Gas mixtures were bubbled into a Petri dish (150 mm25 mm) which was sealed with Parafilm and tilted approximately 10 deg to facilitate the flow of gas through the dish. -tubulin showed the homogeneous presence of the mRNA from the 1-cell stage before the first polar body extrusion [15], although it was previously reported undetected by WISH [66]. BMC Developmental Biol. doi: https://doi.org/10.1242/jeb.038091. All environmental measurements were taken at the location in the pond of the egg masses, and the same site in each pond was used upon repeated visits. Reiko Kuroda. We made field measurements of embryo rotation rates in laboratory-reared Helisoma trivolvis embryos placed in ponds of different trophic levels that ranged geographically from the southern Alberta prairie to the Rocky Mountains. Ford L, Crossley M, Williams T, Thorpe JR, Serpell LC, Kemenes G. Effects of A exposure on long-term associative memory and its neuronal mechanisms in a defined neuronal network. Whole-mount in situ hybridization (WISH) is a common technique used for visualizing the location of expressed RNAs in embryos. A scarcity of genomic data hinders progress in understanding gene expression of Pomacea canaliculata embryogenesis. statement and Commun Biol. Asymmetric inheritance of centrosomally localized mRNAs during embryonic cleavages. Article For example, students could record the heart rate under normal conditions, then subject the eggs to different treatments (such as temperature) and observe the effect on heart rate. Evodevo. Two teams of scientists have announced that they have grown embryo-like structures, made entirely from human stem cells . as associated [21] and by Kuroda et al. Measurements of water temperature, [O2] and rotation rates at Rosebud Complex Pond during June and July 2008. Come and meet the JEB team at the Society for Experimental Biology centenary conference from 4-7 July in Edinburgh, UK. The rotational behaviour of these species was compared in natural environments to assess whether they employed similar ventilation strategies. For example, exposure to 10C resulted in approximately a 50% drop in rotation rate within 10 min, and there were no further changes until embryos were returned to room temperature (Fig. Measurements of water temperature, [O2] and rotation rates at Upper Lloyd Pond during July and August 2008. New York: Wiley; 1998. p. 67107. 2B). PLoS ONE. Chapter The early intracellular chirality is superseded by the intercellular chirality during the third cleavage, leading to asymmetric expression ofnodalandPitxand then to organismal body-handedness [8]. Standard setup for microinjection (a), schematic diagram of the experiment showing an injection to one cell at the two-cell stage (b), and fluorescent images of embryos where half of the cells are expressing DsRed-Express at the 8-cell (c, right panel) and blastula (d, right panel) stages; bright-field images (c and d, left panel) are also included. 2014;58(68):389401. Remarkably, all these characteristics at various developmental stages match with Lsdia1 genotypes without exception, showing that the single gene dictates the handedness directly or indirectly across the biological hierarchy. Development. 2020;20(3):9. Abiotic factors including temperature, pH, conductivity and water oxygen concentration were measured to understand how embryonic rotation is influenced by environmental conditions. Knocking out of Lsdia1 in the dextral snail eggs using the CRISPR/Cas9 technique gave clear-cut results leading to the unequivocal identification of Lsdia1 as the handedness-determining gene [16], which has been sought for nearly a century. We limited the experiments to laboratory-raised snails since the main goals were to test (1) whether experimentally induced changes in embryonic rotation observed under highly controlled laboratory conditions reflect environmentally induced changes in natural environments, and (2) whether O2 or other environmental variables are the primary regulators of rotational activity. In addition to the relatively long lifespan, the animal has another great advantage for neuroscience research, namely it lacks a bloodbrain barrier [51]. Shells consist of calcium carbonate and are typical examples of biominerals. Pond snails primarily lay their egg masses on floating or attached vegetation close to the shore and near the surface of the water (R.B.S., unpublished observations), therefore the containers were placed approximately 1 m from the shore and the buoyancy of the plastic held the containers near the water surface. New York: Liss Inc.; 1982. p. 399483. The genetic factors involved in snail coiling are brought to the embryo by the oocyte cytoplasm. Eggs can be easily removed from the capsule using tweezers, and cultured in 5HF solution. We have established pure dextral and sinistral strains from snails kindly given to us by Dr. Guss Smit (Free University, The Netherlands), which we have been rearing for over 15years [8]. 6). Animal models of neuropsychiatric disorders. During the metamorphosis the larval organs are reduced and the juvenile snail's final organs form; they enable the snail to live on dry land . Cite this article. In oligotrophic ponds, such as Upper Lloyd and Belly River ponds, embryo rotation rates were slower overall, within a fairly narrow range (mean rotation rate 0.60.1 and 0.80.1 r.p.m., respectively), whereas in the highly eutrophic Rosebud pond the embryos exhibited a large range of rotation rates (mean rotation rate 1.00.1 r.p.m.). Results showed that H. trivolvis embryos exhibit differences in rotational behaviour depending on the environmental conditions. Confocal images were obtained with a laser scanning confocal microscope (Zeiss LSM 510). Rotation measurements were taken 10 min after the start of gas perfusion. These were possible as L. stagnalis is prolific, however, creating linkage markers was not easy due to lack of an annotated genome database.