Differences in predatory pressure on terrestrial snails by birds and mammals

The evolution of shell polymorphism in terrestrial snails is a classic textbook example of the effect of natural selection in which avian and mammalian predation represents an important selective force on gene frequency. However, many questions about predation remain unclear, especially in the case of mammals. We collected 2000 specimens from eight terrestrial gastropod species to investigate the predation pressure exerted by birds and mice on snails. We found evidence of avian and mammalian predation in 26.5% and 36.8% of the shells. Both birds and mammals were selective with respect to snail species, size and morphs. Birds preferred the brown-lipped banded snail Cepaea nemoralis (L.) and mice preferred the burgundy snail Helix pomatia L. Mice avoided pink mid-banded C. nemoralis and preferred brown mid-banded morphs, which were neglected by birds. In contrast to mice, birds chose larger individuals. Significant differences in their predatory pressure can influence the evolution and maintenance of shell size and polymorphism of shell colouration in snails.     

Comparison of heart rate in embryonic,young and adult Achatina fulica

We have studied the embryonic heart in the gastropod Achatina fulica using eggs soon after their deposition. We also followed the development of organs, with the main emphasis on the heart and its physiology. The embryos were examined at different stages by carefully removing egg shell until hatching. In this context the heart rate (HR) was analysed in embryonic snails and compared with that of young (from hatching) and adults. The HR of embryos dissected from newly deposited eggs was irregular, with a mean frequency of 0.42?±?0.14?Hz. The heartbeat during the ontogeny was more rhythmic and HR increased to 0.82?±?0.12?Hz. The intersystolic intervals (ISI) in real time showed a Gaussian distribution for all animals. The peak ISI from Gaussian fit closely matched the cumulative probability for corresponding data. Although the HR increased after hatching, comparisons yield a weak correlation (R?=?0.56?±?0.27) with the total body weight of embryonic, young and adult snails.     

Leucomyosuppressin modulates cardiac rhythm in the cockroach Blattella germanica

Several lines of evidence point to leucomyosuppressin (LMS) and myosuppressin-related peptides as inhibitory modulators of heartbeat frequency in arthropods. Previous studies in Blattella germanica demonstrated that heartbeat frequency decreases after ootheca formation, and remains low during the period of ootheca transport. Subsequent work in this cockroach resulted in the characterization of LMS and the cloning and sequencing of its precursor. The present paper describes the activity of LMS on modulation of heartbeat in B. germanica. Assays using semi-isolated heart preparations revealed that LMS reduces heartbeat frequency in a dose dependent manner, at physiological concentrations. Additional experiments showed that LMS inhibits heartbeat rates in vivo. Finally, injection of dsRNA for LMS elicited a decrease in LMS mRNA to virtually undetectable levels and heartbeat frequency increased significantly in females carrying oothecae. These data suggest that LMS contributes to the modulation of cardiac rhythm in B. germanica during the reproductive cycle.     

Glycolytic adjustments in tissues of frog Rana ridibunda and land snail Helix lucorum during seasonal hibernation

The present work aimed to contribute to the understanding of the adaptation of the glycolytic pathway in tissues of frog Rana ridibunda and land snail species Helix lucorum during seasonal hibernation. Moreover responses of glycolytic enzymes from cold acclimated R. ridibunda and H. lucorum were studied as well. The drop in Po₂ in the blood of hibernated frogs and land snails indicated lower oxygen consumption and a decrease in their metabolic rate. The activities of glycolytic enzymes indicated that hibernation had a differential effect on the glycolyis in the two species studied and also in the tissues of the same species. The activity of l-LDH decreased significantly in the skeletal muscle and heart of hibernated R. ridibunda indicating a low glycolytic potential. Similar biochemical responses were observed in the same tissues during cold acclimation. The continuous increase in the activities of glycolytic enzymes studied, except for HK, might indicate a compensation for the impacts of low temperature on the enzymatic activities. In contrast to R. ridibunda, the activities of the enzymes increased and remained at higher levels than those of the prehibernation controls indicating maintenance of glycolytic potential in the tissues of hibernating land snails.     

Acetylcholine inhibits nitric oxide (NO) synthesis in the gastropod nervous system

Acetylcholine (ACh) is one of the main signals regulating nitric oxide synthase (NOS) expression and nitric oxide (NO) biosynthesis in mammals. However, few comparative studies have been performed on the role of ACh on NOS activity in non-mammalian animals. We have therefore studied the cholinergic control of NOS in the snail Helix pomatia and compared the effects of ACh on NO synthesis in the enteric nervous system of the snail and rat. Analyses by the NADPH-diaphorase reaction, immunocytochemistry, purification with ion-exchange chromatography, Western-blot, and quantitative polymerase chain reaction have revealed the expression of neuronal NOS in the rat intestine and of a 60-kDa subunit of NOS in the enteric nerve plexus of H. pomatia. In H. pomatia, quantification of the NO-derived nitrite ions has established that NO formation is confined to the NOS-containing midintestine. Nitrite production can be elevated by L-arginine but inhibited by N_ω-nitro-L-arginine. In rats, ACh moderately elevates nitrite production, whereas ACh, the nicotinic receptor agonists (nicotine, acetyl thiocholine iodide, metacholine) and the cholinesterase inhibitor eserine reduce enteric nitrite formation in snails. The nicotinic receptor antagonist tubocurarine also provokes nitrite liberation, whereas the muscarinic receptor agonists or antagonists have no significant effect in snails. In the presence of EDTA or tetrodotoxin, ACh fails to inhibit nitrite production. In pharmacological studies, we have found that ACh contracts the midintestinal muscles and, in snails, simultaneously reduces the antagonistic muscle relaxant effect of L-arginine. Our experiments provide the first evidence for an inhibitory regulation of neuronal NO synthesis by ACh in an invertebrate species. This article is dedicated to Dr. Gábor Hollósi on the 50th anniversary of his graduation and being a teacher at the University of Debrecen.     

Regeneration of excised shell by the invasive apple snail Pomacea canaliculata

After excision of shell from Pomacea canaliculata, survival rates, repair process, haemocyte response, and calcium content were observed and quantified for three weeks. The following experimental treatments were used: black-colored individuals with large (BL-group) or small (BS-group) shell heights, yellow-colored individuals with large (YL-group) or small (YS-group) shell heights. The survival rates in BL-, YL-, BS-, and YS-groups after making partial excisions of snail shells were, respectively, 93.59, 94.87, 92.31, and 96.15%. Freshly regenerated shell could be seen at 1 day among the four groups after induction of shell regeneration. Regeneration shell filled the wound after 5–10 days. The area of regenerated shell in yellow-colored individuals was larger than that of black-colored individuals, but the thickness of regenerated shell was not significantly different. Multiple (four times) inductions of shell regeneration significantly enhanced the thickness of newly formed shells. Two types of circulating haemocytes (hyalinocytes and granulocytes) were identified under light microscopy based on Wright’s staining. Artificial induction of shell regeneration rendered a significant increase in the number of total circulating haemocytes which was followed by a decrease to pre-wounding levels. This peak value of total circulating haemocytes was 2.86, 2.43, 1.69, and 1.71-fold higher than pre-wounding levels in group BL, YL, BS, and YS, respectively. The number of total circulating haemocytes in yellow-colored individuals was significantly higher than in black-colored. Calcium concentrations in the mantles of snails are favorable for calcium nucleation. It is postulated that calcium content increased in the mantle increase at the start of the experiment and then returned to pre-wounding levels at the end of the experiment. This study shows that apple snails have effective shell regeneration abilities and that haemocytes and calcium transportation appear to play an important role in shell growth and regeneration.     

Assessment of the status of wild populations of land snail (escargot) Helix pomatia L. in Moldova: the effect of exploitation

Helix pomatia L., the Roman snail, is a species faced with growing commercial interest in Moldova. Its life history characteristics (slow maturation and recruitment, high mortality among juveniles and low fecundity) along with its strong spatial aggregation, makes it especially vulnerable to exploitation. In this study, differences in density, shell size and age distribution were assessed in 7 unexploited and 10 exploited sites in the northern and central parts of Moldova. A significant impact of exploitation on snail population densities, shell size of adult snails and age distribution was revealed. Exploited sites had much lower densities than unexploited ones and in two places no live snails were found. This may suggest that exploitation is currently carried out at an unsustainable level, but additional information on the demography of populations and intensity of exploitation is required in order to make inferences regarding sustainability and long-term population management. There was a higher proportion of adult snails in exploited sites than in non-exploited, because of the collection strategies: not only adults, but also all other age groups are gathered. Bigger adult shell size in exploited sites may be related to lower population density, but further study is required to confirm this. Establishing of well-organized population monitoring systems and development of snail breeding enterprises are proposed in order to conserve the species in Moldova.     

Etude exploratoire de la spermatogenèse induite par la chaleur chez l'escargot Helix aspersa en hibernation: Rôle du cerveau / An exploratory study on temperature-induced spermatogenesis in the hibernating snail Helix aspersa: the role of the brain

Summary

The male cells in the ovotestis of hibernating snails undergo multiplication when the temperature of the environment is raised from 5°C to 25°C. If the temperature is maintained at 25°C for 4 weeks the process of spermatogenesis is completed but the rate of spermatogenesis (DNA synthesis) starts decreasing from the 3rd week (Table 1; Fig. 1).

Brain ablation in hibernating snails maintained at 25°C causes a significant increase in DNA synthesis exclusively in male cells of the ovotestis. This suggests that the brain exerts an inhibitory influence on spermatogenic multiplication. This influence is effective only during the first and the fourth week of exposure of hibernating snails to 25°C (Fig. 1; Table 1) indicating the existence of an endogenous cyclical control. Spermiogenesis is, however, not affected by brain extirpation (Fig. 4 A,B,C).

When reimplanted in the head haemocoel the brain appears normal histologically (Fig. 5 A,B) and it reestablishes the inhibitory influence on DNA synthesis in the ovotestis only during the first day of temperature-induction. During the 1st, 3rd and 4th week the reimplanted brain, deprived of its neural connections, fails to exert its inhibitory influence suggesting that for this influence to function neural connections to the brain are essential. Surprisingly, the implanted brain seems to inhibit DNA synthesis during the 2nd week of temperature-induction (Table 1).

These experiments show that the brain control temperature-induced spermatogenic multiplication in the ovotestis in snails at the onset of hibernation and this control is exerted by one or more inhibitory factors originating from the brain which may function in concert or independently to produce the neuroendocrine effect. It seems therefore justified to consider spermatogenesis in hibernating snails as being neuroendocrinologically controlled.     

Factors affecting the distribution and abundance of the commensal <Emphasis Type="Italic">Temnocephala iheringi</Emphasis> (Platyhelminthes: Temnocephalidae) among the southernmost populations of the apple snail <Emphasis Type="Italic">Pomacea canaliculata </Emphasis>(Mollusca: Ampullariidae)

Temnocephala iheringi is the most common temnocephalan inhabiting the mantle cavity of the apple snail Pomacea canaliculata, a freshwater neotropical gastropod that has become a serious rice pest in Southeastern Asia. T. iheringi has been recorded from Mato Grosso (Brazil) to water bodies associated with the Río de la Plata river (Argentina). During an extensive survey in the southern limit of the native area of P.␣canaliculata the presence of T. iheringi eggs was recorded in several apple snail populations, extending the known distribution of the commensal more than 400 km southwards. The aim of this study was to understand the factors affecting the distribution and abundance of T. iheringi among populations of P.␣canaliculata. Only 23% of the apple snail populations inhabiting streams harboured temnocephalans while the occurrence among lentic ones was 71%. T. iheringi was found mostly in populations of apple snails living in non-alkaline sites and where snails attaining sizes larger than 4 cm were very common. The prevalence of the temnocephalans in lentic populations was higher than 90%. The number of eggs on the shell (not including the umbilicus) ranged between 0 and 470 and was different among populations of P.␣canaliculata. The prevalence and number of eggs were lower in the lotic populations, except for a stream population immediately downstream of a lake with commensals. There was no difference between males and females of P. canaliculata neither in the prevalence nor in the number of eggs on the shell. The southernmost population of the world of P. canaliculata harbours commensals that tolerate cold winter water temperatures (4–5 °C) as well as its host. On the other hand, T. iheringi was found only in sites with bicarbonate concentrations lower than 6.6 meq l⁻¹, suggesting that the tolerance of the commensal is very much lower than that of the apple snail (up to 9.95 meq l⁻¹). The number of worms inside each snail or the life history variation of P. canaliculata could explain the influence of the size of the snails on the occurrence of T. iheringi. In the big-sized snails, where the number of commensals is higher, the probability of survival of at least one worm is also higher, specially during the hibernation period, when crawling and feeding are null and snails remain buried. On the other hand, P. canaliculata snails from lentic populations are generally bigger and mostly iteroparous, while those inhabiting streams are smaller and semelparous. In these populations the snails have access to mate only with snails of their same cohort, while in iteroparous populations they can copulate with individuals of other cohorts, allowing the inter-generation transmission of worms and the long term persistence of the population of commensals.     

The effect of carbonic anhydrase,urea and urease on the calcium carbonate deposition in the shell-repair membrane of the snail,Helix pomatia L.

Summary The effect of carbonic anhydrase (CA), urea and urease on the CaCO₃ deposition in the shell-repair membrane of the snail, Helix pomatia, was studied by injection of CA separately or in combination with urease. This treatment resulted in increased deposits of CaCO₃ and apparent crystal formation within the shell-repair membranes compared with those of the controls. The reactions to CA combined with urea were not uniform. Formation of organic crystalline structures and dendritic spherulites was observed in some of these membranes, whereas the deposition of CaCO₃ crystals was suppressed. Administration of urea alone inhibited the formation of large CaCO₃ crystals, whereas urease stimulated this process. The reaction of young snails was greater compared to adults. The membranes of young snails contained tighly packed, small CaCO₃ crystals and organic crystalline structures, which indicated increase of the calcifying centra and their successive mineralization. The results support the assumption that carbonic anhydrase and urease enhance the rate of calcium carbonate deposition and crystal formation in Helix pomatia.     

Adjustment of metabolite composition in the haemolymph to seasonal variations in the land snail <Emphasis Type="Italic">Helix pomatia</Emphasis>

In temperate regions, land snails are subjected to subzero temperatures in winter and hot temperatures often associated to drought in summer. The response to these environmental factors is usually a state of inactivity, hibernation and aestivation, respectively, in a temperature and humidity buffered refuge, accompanied by physiological adjustments to resist cold or heat stress. We investigated how environmental factors in the microhabitat and body condition influence the metabolite composition of haemolymph of the endangered species Helix pomatia. We used UPLC and GC–MS techniques and analyzed annual biochemical variations in a multivariate model. Hibernation and activity months differed in metabolite composition. Snails used photoperiod as cue for seasonal climatic variations to initiate a physiological state and were also highly sensitive to temperature variations, therefore constantly adjusting their physiological processes. Galactose levels gave evidence for the persistence of metabolic activity with energy expenditure during hibernation and for high reproductive activity in June. Triglycerides accumulated prior to hibernation might act as cryoprotectants or energy reserves. During the last month of hibernation snails activated physiological processes related to arousal. During activity, protein metabolism was reflected by high amino acid level. An exceptional aestivation period was observed in April giving evidence for heat stress responses, like the protection of cells from dehydration by polyols and saccharides, the membrane stabilization by cholesterol and enhanced metabolism using the anaerobic succinic acid pathway to sustain costly stress responses. In conclusion, physiological adjustments to environmental variations in Helix pomatia involve water loss regulation, cryoprotectant or heatprotectant accumulation.     

Purification of cadmium-binding proteins from related species of terrestrial helicidae (gastropoda,mollusca): A comparative study

Summary Three species of terrestrial Helicidae (Helix pomatia, Cepaea hortensis andArianta arbustorum) were fed cadmium-rich diet in the laboratory. The snails accumulated high amounts of the metal in their hepatopancreas. Most cadmium and some zinc were found, after centrifugation, in the soluble fractions from which a cadmium-binding protein was isolated for each species by ion exchange and gel chromatography. The proteins contained different amounts of cadmium, but little or no zinc, and showed high absorption at 254 nm indicating the presence of cadmium-mercaptide bonds. After gel filtration, a molecular weight of 12000 was found for cadmium-binding proteins fromHelix pomatia andArianta arbustorum, whereas a molecular weight of 10 000 was found for a cadmium-binding protein fromCepaea hortensis. SDS-polyacrylamide gel electrophoresis showed one single band for each protein fromHelix pomatia andArianta arbustorum and suggested a molecular weight of 11000 for both species. Amino acid analysis revealed, for each protein, high amounts of cysteine (12–20%), glycine (15–19%), and serine (12–14%), and moderately elevated contents of lysine (9–13%) and alanine (4–8%), but no methionine and only traces, if any, of aromatic amino acids. The ratios of cadmium to cysteine were 1:5, 1:10 and 1:3 in the proteins fromHelix pomatia,Cepaea hortensis andArianta arbustorum, respectively. Some features of the isolated proteins resembled mammalian metallothioneins. Most characteristics, however, differed from true metallothioneins and were similar to cadmium-binding proteins found in some marine molluscs.     

Altered feeding response as a cause for the altered heartbeat rate and locomotor activity of Schistosoma mansoni-infected biomphalaria glabrata

Biomphalaria glabrata infected with Schistosoma mansoni for 33 days fed more often than uninfected snails. Whereas uninfected snails had nocturnal increases in feeding, snails with a 33-day-old infection of S. mansoni fed as often during the day as in the night. Using direct observation and film analysis, we found that feeding increased the heartbeat rate and locomotor activity of B. glabrata. When snails were allowed to feed ad lib., infected snails had higher heartbeat rates than uninfected snails both during the day (P less than 0.01) and the night (P less than 0.001). However, when the snails were deprived of food for 24 hr, infected snails had slightly higher heartbeat rates than uninfected snails only during the day (P less than 0.05). There was no difference between the heartbeat rates of feeding, infected snails and the heartbeat rates of uninfected snails that were starved for 8 hr, and then allowed to feed. Uninfected snails had nocturnal increases in heartbeat rate regardless of feeding schedule, but infected snails had greater nighttime heartbeat rate than daytime heartbeat rate only when they were not allowed to feed. Infected snails had less nocturnal locomotor activity than uninfected snails when feeding, but there was no difference between the locomotor activity of infected and uninfected snails when the snails were deprived of food for 24 hr. Absence of food also resulted in an increased nighttime to daytime ratio of locomotor activity of infected snails. These results suggest that the increased heartbeat rate and altered rhythms of heartbeat rate and locomotor activity in B. glabrata infected with S. mansoni for 33 days were caused by the altered feeding response of these snails.     

Onset of heartbeat revealed by successive structural changes in the developing single embryonic heart of the waterstrider (Gerris paludum insularis)

Videofilm images of the heartbeat in the living embryos of the waterstrider, Gerris paludum insularis, were analyzed to demonstrate successive changes in the width of the contractile heart at the different developmental stages. This information is graphically represented and termed structural cardiogram. Onset of the embryonic heartbeat characterized by anteriorly spreading peristaltic movement of the heart wall occurs at about 55% HL (percent heart length) as early as at about 81 h after katatrepsis (K+81 h embryo). This peristaltic wave occurs almost always following swinging movement of abdominal tip observed exclusively at this stage. Similar peristaltic wave of the heart wall may also be observed at later stages, exclusively in the anterior two-fifth of the heart. Conduction velocity of the peristaltic wave estimated from structural cardiogram of K+81 h embryo was approximately 0.57 mm/s; it was approximately 1.33 mm/s in the K+102 h embryos. In the posterior three-fifth of the heart, however, rhythmic movement was not peristaltic. Development of heartbeat generator in the specific region of the heart was discussed in relation to the onset of embryonic heartbeat.     

Adaptive plasticity in predator-induced defenses in a common freshwater snail: altered selection and mode of predation due to prey phenotype

Studies of putatively adaptive plasticity, such as inducible defenses, frequently explore the fitness consequences of expressing alternative phenotypes in alternative environments, but few studies examine how and why the pattern of selection changes in relation to trait induction. We induced snails in the presence/absence of nonlethal predatory crayfish, exposed both phenotypes (alone and combined) to selection by lethal crayfish, and quantified linear and nonlinear selection differentials. Crayfish induced an increase in mass, shell thickness, and absolute (but not relative) shell dimensions. Crayfish predation on uninduced snails was rapid, accomplished via shell-crushing and revealed strong selection for increased size (i.e., mass and shell dimensions). Conversely, crayfish predation on predator-induced snails was slower, often accomplished using an alternative mode of predation (shell-crushing 70% of the time, but shell-extraction 30% of the time), and revealed selection for wide apertures and thick shells. Crayfish selection on uninduced snails in the presence of predator-induced snails was stronger than predation on uninduced snails alone demonstrating that selection can be frequency dependent. Therefore, predator-induced changes in size and shell thickness appear to be adaptive and, along with reciprocal adjustments in the mode of predation, result in altered patterns of selection.     

Effect of serotonin and acetylcholine on neurons in the central nervous system of snails

Differences in the distribution of neurons distinguished by their responses to serotonin and acetylcholine were found in the central nervous system ofHelix pomatia. When applied to the body of the neuron acetylcholine hyperpolarizes the cell more often than it depolarizes it, but depolarization predominates in some regions, e.g., on the dorsal surface of the visceral ganglion. In most cases serotonin stimulates activity and induces depolarization or the appearance of pacemaker oscillations of membrane potential. The oscillogenic effect of serotonin is characteristic, in particular, of white (peptidergic) neurons and the depolarization effect is characteristic of other neurons, including the paired giant metacerebral neurons which contain serotonin in their cytoplasm. Both effects failed to appear in sodium-free solution. A group of neurons in which hyperpolarization was observed in response to serotonin application was found in the visceral ganglion of hibernating snails. The same cells in active snails were stimulated by serotonin. A giant neuron with two variously located cholinergic structures is present on the ventral surface of the ganglion among this group of cells: acetylcholine hyperpolarized it when applied to the cell body but depolarized it when applied to the axon.     

Effects of deuterium oxide and temperature on heart rate in Drosophila melanogaster

A non-intrusive optical technique has been developed to monitor heartbeat in late third-instar Drosophila larvae. Heartbeat in this insect is an oscillation that is not temperature compensated. Deuterium oxide lengthens the period of a number of high and low frequency oscillators and clocks in a variety of organisms. To determine whether deuterium affects heart rate, flies were raised on proteated and deuterated media and their heartbeat was monitored at four temperatures ranging from 18 to 33 degrees C. The rate of heartbeat increased linearly with increasing temperature, and decreased with increasing concentrations of deuterium. There was a significant interaction between temperature and deuterium: the higher the concentration of deuterium oxide the less temperature-sensitive was the heart rate. Raising temperatures also increased the amount of "noise" in the rhythm: signal-to-noise ratio, which characterizes the amount of power in a rhythmic signal, decreased with increasing temperatures. Deuterium oxide had no effect on signal-to-noise ratio.     

红树林恢复初期莱氏锥滨螺分布动态

树栖腹足类动物是红树林底栖动物的重要组成部分,其组成和分布受到红树植被的影响。因此,在红树林生态修复中,腹足类动物的恢复依赖于植被的发育。滨螺科(Littorinidae)锥滨螺属(Mainwaringia)动物是亚洲红树林的广布种,但针对其在红树林中的分布及种群特征的研究较少,对红树林植被恢复过程中锥滨螺属动物的恢复动态更是鲜有研究。调查了厦门下潭尾湿地秋茄(Kandelia obovata)红树林恢复初期,新记录种莱氏锥滨螺(Mainwaringia leithii)种群恢复的时间动态,并分析其与植被参数的关系。研究发现,红树林恢复初期,秋茄植被生长迅速,株高、冠幅、基径和覆盖度分别由0.5年生幼林的41.3 cm、25.0 cm、1.04 cm和25%增长为8年生样地的179.2 cm、76.7 cm、5.96 cm和95%。在秋茄胚轴种植6个月左右开始记录到莱氏锥滨螺的个体,其密度和生物量在1.5 a后达到最大(分别为136个/m²和1.86 g/m²),而后逐渐降低,种植3 a后秋茄林内莱氏锥滨螺仅零星分布。除8年生的样地,莱氏锥滨...     

Nematode and snail metallothioneins

Metallobiologists have, at large, neglected soil dwelling invertebrates; exceptions are the nematode (Caenorhabditis elegans) and snails (Helix pomatia and Cantareus aspersus). This review aims to compare and contrast the molecular, protein and cellular mechanisms of the multifunctional nematode and snail metallothioneins (MTs). The C. elegans genome contains two MT genes, mtl-1, which is constitutively expressed in the pharynx and likely to act as an essential and/or toxic metal sensor, and mtl-2, which plays a negligible role under normal physiological conditions but is strongly induced (as mtl-1) in intestinal cells upon metal exposure. It has been possible to follow the intricate phenotypic responses upon the knockdown/knockout of single and multiple MT isoforms and we have started to decipher the multifunctional role of C. elegans MTs. The snails have contributed to our understanding regarding MT evolution and diversity, structure and metal-specific functionality. The H. pomatia and C. aspersus genomes contain at least three MT isoform genes. CdMT is responsible for cadmium detoxification, CuMT is involved in copper homeostasis and Cd/CuMT is a putative ancestral MT possibly only of minor importance in metal metabolism. Further investigations of nematode, snail and other invertebrate MTs will allow the development of alternative biomarker approaches and lead to an improved understanding of metallobiology, protein evolution and toxicogenomics.