[Show abstract][Hide abstract] ABSTRACT: Land snails are subject to daily and seasonal variations in temperature and in water availability, and use heat shock proteins (HSPs) as part of their survival strategy. We used experimental heat stress to test whether adaptation to different habitats affects HSP expression in two closely related Sphincterochila snail species, a desert species, Sphincterochila zonata, and a Mediterranean-type species, Sphincterochila cariosa. Our findings show that in S. cariosa, heat stress caused rapid induction of Hsp70 proteins and Hsp90 in the foot and kidney tissues, whereas the desert-inhabiting species S. zonata displayed delayed induction of Hsp70 proteins in the foot and upregulation of Hsp90 alone in the kidney. Our study suggests that Sphincterochila species use HSPs as part of their survival strategy following heat stress and that adaptation to different habitats results in the development of distinct strategies of HSP expression in response to heat, namely the reduced induction of HSPs in the desert-dwelling species. We suggest that the desert species S. zonata relies on mechanisms and adaptations other than HSP induction, thus avoiding the fitness consequences of continuous HSP upregulation.
Cell Stress and Chaperones 04/2012; 17(5):639-45. · 2.48 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Polmunate land snails are subject to stress conditions in their terrestrial habitat, and depend on a range of behavioural, physiological and biochemical adaptations for coping with problems of maintaining water, ionic and thermal balance. The involvement of the heat shock protein (HSP) machinery in land snails was demonstrated following short-term experimental aestivation and heat stress, suggesting that land snails use HSPs as part of their survival strategy. As climatic variation was found to be associated with HSP expression, we tested whether adaptation of land snails to different habitats affects HSP expression in two closely related Sphincterochila snail species, a desert species Sphincterochila zonata and a Mediterranean-type species Sphincterochila cariosa. Our study suggests that Sphincterochila species use HSPs as part of their survival strategy following desiccation and heat stress, and as part of the natural annual cycle of activity and aestivation. Our studies also indicate that adaptation to different habitats results in the development of distinct strategies of HSP expression in response to stress, namely the reduced expression of HSPs in the desert-inhabiting species. We suggest that these different strategies reflect the difference in heat and aridity encountered in the natural habitats, and that the desert species S. zonata relies on mechanisms and adaptations other than HSP induction thus avoiding the fitness consequences of continuous HSP upregulation.
Cell Stress and Chaperones 04/2012; 17(5):523-7. · 2.48 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Land snails are subject to daily and seasonal variations in temperature and in water availability and use heat shock proteins (HSPs) as part of their survival strategy. We tested whether the reproductive cycle of land snails affects the endogenous levels of HSPs, and their involvement in the reproductive process. We examined HSP levels in the foot tissue of two Sphincterochila species, S. cariosa and S. zonata, before and after laying eggs, and analyzed the albumen gland (reproductive organ) of both species and eggs of S. cariosa for the presence and quantity of various HSPs. Our study shows reduction in the expression level of Hsp70 isoforms and Hsp90 in S. zonata foot and of Hsp74 in S. cariosa foot during the period preceding egg laying compared to the post-reproductive stage. Hsp70 isoforms and Hsp25 were highly expressed in both large albumen glands and in freshly laid eggs of S. cariosa, whereas large albumen glands of S. zonata expressed mainly Hsp70 isoforms. We conclude that a trade-off between survival and fertility is responsible for the expression level of HSPs in the foot tissue of Sphincterochila snails. Our study shows that HSPs are involved in the reproductive process. We propose that parental provision of HSPs may be part of a "be prepared" strategy of Sphincterochila snails, and that HSPs may play important roles in the survival strategy of land snails during the early life stages. Our observations also highlight the importance of the reproductive status in study of whole organisms, especially when assessing the HSP response to stress.
Comparative biochemistry and physiology. Part A, Molecular & integrative physiology 06/2011; 160(2):149-55. · 2.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Land snails are subject to daily and seasonal variations in temperature and in water availability, and have evolved annual cycles of activity and aestivation as part of their survival strategy. We tested in the field whether adaptation to different habitats affects the endogenous levels of heat shock proteins (HSPs) in two closely related Sphincterochila snail species, a desiccation-resistant desert species, Sphincterochila zonata, and a Mediterranean-type, desiccation-sensitive species, S. cariosa. We examined HSP levels in various tissues of snails during aestivation and after resumption of activity. Our study shows that, during aestivation, S. cariosa had higher standing stocks of Hsp70 in the foot and the hepatopancreas, and of small HSPs (sHSPs) in all the examined tissues, whereas S. zonata had higher stocks of Hsp70 in the kidney and of Hsp90 in the kidney and in the hepatopancreas. Arousal induced a general upregulation of HSPs, except for Hsp90, the expression of which in the foot was higher during aestivation. We suggest that the stress protein machinery is upregulated during arousal in anticipation of possible oxidative stress ensuing from the accelerating metabolic rate and the exit from the deep hypometabolic state. Our findings support the concept that, in land snails, aestivation and activity represent two distinct physiological states, and suggest that land snails use HSPs as important components of the aestivation mechanism, and as part of their survival strategy during and after arousal. Our study also indicates that adaptation to different habitats results in the development of distinct strategies of HSP expression with likely consequences for the ecology and distribution of land snails.
[Show abstract][Hide abstract] ABSTRACT: Land snails are subject to daily and seasonal variations in temperature and in water availability and depend on a range of behavioral and physiological adaptations for coping with problems of maintaining water, ionic, and thermal balance. Heat shock proteins (HSPs) are a multigene family of proteins whose expression is induced by a variety of stress agents. We used experimental desiccation to test whether adaptation to different habitats affects HSP expression in two closely related Sphincterochila snail species, a desiccation-resistant, desert species Sphincterochila zonata, and a Mediterranean-type, desiccation-sensitive species Sphincterochila cariosa. We examined the HSP response in the foot, hepatopancreas, and kidney tissues of snails exposed to normothermic desiccation. Our findings show variations in the HSP response in both timing and magnitude between the two species. The levels of endogenous Hsp72 in S. cariosa were higher in all the examined tissues, and the induction of Hsp72, Hsp74, and Hsp90 developed earlier than in S. zonata. In contrary, the induction of sHSPs (Hsp25 and Hsp30) was more pronounced in S. zonata compared to S. cariosa. Our results suggest that land snails use HSPs as part of their survival strategy during desiccation and as important components of the aestivation mechanism in the transition from activity to dormancy. Our study underscores the distinct strategy of HSP expression in response to desiccation, namely the delayed induction of Hsp70 and Hsp90 together with enhanced induction of sHSPs in the desert-dwelling species, and suggests that evolution in harsh environments will result in selection for reduced Hsp70 expression.
Cell Stress and Chaperones 12/2009; 15(4):351-63. · 2.48 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Land snails are subject to desiccating conditions in their terrestrial habitat. Our previous studies have revealed significant differences in resistance to desiccation among closely related species and among genera that share a similar life style, suggesting that the distribution pattern is correlated with the abiotic regime in its specific habitat. Our present study extends the scope of comparison to the intraspecific level, by examining the resistance to desiccation in five populations of Xeropicta vestalis, a Mediterranean-dwelling species that ranges from the 1000 mm to the 200 mm isohyet.The resistance to desiccation varied among populations in correlation with the specific habitat of each population and with the north-to-south and the west-to-easl climatic gradients. Furthermore, in one case it exceeded the resistance of other, desert-dwelling species (Trochoidea simulata, Sphincterochila zonata). We suggest that, in spite of its physiological capacity to invade deserts, X. vestalis is prevented from doing so because it is an annual, semelparous species. The Negev Desert is an unpredictable environment, susceptible to year-to-year fluctuations to such an extent that one rainless year would wipe out all its populations.
[Show abstract][Hide abstract] ABSTRACT: This study examines the water economy and resistance to desiccation in a minute (5 mg snail mass; 3 mm shell height) litter-dwelling land snail Lauria cylindracea (Pupillidae). As expected from its small size and from its moist habitat, L. cylindracea exposed to normothermic desiccation lost water at the highest rate revealed so far in our studies of resistance to desiccation in some 30 Israeli species and populations of land snails—22.7% of the whole snail mass within 5 days. This high water loss was selectively contributed by the extra-pallial (free) compartment while soft body water content was closely maintained, without catabolism of body tissue as a source of metabolic water. Surprisingly, however, samples of L. cylindracea survived long periods (2–4 months) of aestivation when left undisturbed in the laboratory, sustaining a mass loss of 25–40%. This long-term aestivation revealed a different pattern of water compartmentalization, as the snails also lost water from the soft body tissue. Samples of these snails were rehydrated for 48 h and then exposed to an identical desiccation regime as the original, field-collected snails. Most of the water taken up during rehydration was lost within the first 24 h of desiccation, after which the rate of water loss dropped sharply. We conclude that short-term water regulatory responses to experimental desiccation differ from long-term responses to aestivation. We suggest that during long-term aestivation, a new set-point of water economy is established, in association with a metabolic depression, and that an extended period of contact with moisture is needed to change this set-point.
[Show abstract][Hide abstract] ABSTRACT: We have examined the resistance to desiccation among rock-dwelling land snails of various phylogenetic groups:Cristataria genezarethana (Clausiliidae),Rupestrella rhodia (Chondrinidae) andLevantina caesareana (Helicidae), all from the same location in Israel.L. caesareana was the most resistant andR. rhodia the least resistant to desiccation andC. genezarethana was of intermediate resistance. Differences in the rates of water loss during desiccation were determined mainly by rate of water loss during the first 2 days of desiccation. The high rates of water loss in rock-dwelling species exceed those of other snails in the Mediterranean habitat of Israel. However, snails collected in the field at the end of aestivation were in only a mild state of dehydration, suggesting that the rocky habitat protects its occupants against desiccation. We also suggest that among the rock-dwelling species, the protective role of the rock is more important in the more evolutionarily primitive genera (the chondrinidRupestrella and the clausiliidCristataria) and that physiological capacities are more effective in the more highly evolved helicidLevantina.
International Journal of Biometeorology 01/1995; 38(2):78-83. · 2.59 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Theba pisana is a bush-dwelling snail with a circum-Mediterranean distribution. In Israel it is limited to a narrow coastal strip, along which there is a north-to-south gradient in mean annual rainfall (700–300 mm per year). In this study we found significant intraspecific differences among populations ofT. pisana in resistance to desiccation along this gradient, and in a population from Greece, which may be grossly correlated with the climatic gradient. The Greek population was the least resistant to desiccation with an extremely high rate of water loss. The differences in total mass loss were mainly determined by the rate of water loss during the first 4 days of desiccation. A general phenomenon during desiccation was the close regulation of the soft body water content at the expense of the extra-pallial fluid compartment.
International Journal of Biometeorology 11/1993; 37(4):183-189. · 2.59 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Resistance to desiccation was examined in six populations of the Israeli bush-dwelling snail Trochoidea simulata, a desert species distributed mainly between the 100–200 mm isohyets.The present study revealed significant intraspecific differences in resistance to desiccation which are correlated with habitat and climatic gradients within the distribution range of the species. Populations from more arid sites were more resistant to desiccation and heat exposure than those from more mesic areas. However, the population from the Rift Valley (an extremely arid region) was surprisingly poorly resistant. Rates of population water loss under the controlled experimental conditions in the laboratory generally matched the calculated water losses during natural summer aestivation.
[Show abstract][Hide abstract] ABSTRACT: 1.1. Small crabs survived over 18% water loss and large crabs 21% when in dry air. Size, temperature and relative humidity affected this rate.2.2. Haemolymph osmolarity of newly collected crabs ranged from 530 to 630 mOsm/kg, depending on their size and the season.3.3. When dehydrated, haemolymph osmolarity rose to over 700 mOsm/kg, and ion concentration increased by over 10%.4.4. Crabs survived in sea-water for at least two weeks. Haemolymph osmolarity rose and ion concentration increased. The acclimation pattern affected the haemolymph osmolarity.
Comparative Biochemistry and Physiology Part A: Physiology. 01/1984;
[Show abstract][Hide abstract] ABSTRACT: Five amphibian species were studied for the effect of hypophysial hormones on their water balance. The species were three anurans, Rana ridibunda, Bufo viridis and Pelobates syriacus, and two urodeles Salamandra salamandra and Triturus vittatus. In the first four species different stages of development were studied, in the newt both the terrestrial and aquatic phases of the adult were examined. The hormones used were oxytocin (OXY), arginine vasotocin (AVT) and prolactin (PL). Oxytocin caused most water retention when compared with the other hormones, especially responding were juveniles of Rana and Bufo, but also the terrestrial phase of the adult newt Triturus. Arginine vasotocin affected mostly juvenile Pelobates. Prolactin caused water retention in juvenile Rana and in the terrestrial phase of Triturus. In general the hormones affected the juvenile stages more than either larvae or adults.
Comparative Biochemistry and Physiology Part A Physiology 02/1983; 75(3):447-55. · 2.17 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 1.1. Blood plasma osmolarity and ion concentration, and intra-cellular fluids (muscle) were determined in juvenile toadlets in tap water, in wet soil and after dehydration of 18% body weight or following acclimatization to 400 mM/1 urea.2.2. Plasma concentration increased during dehydration (375 mOsm/kg), after three months in soil (415 mOsm/kg), and after acclimatization to 400 mM/1 urea (540 mOsm/kg).3.3. In hydrated toadlets Na+ and Cl− accounted for 81% and urea for 2%, the latter increased to 22% when in soil.4.4. Urea concentration was higher in muscle of toadlets burrowed in soil or following acclimatization to 400 mM/1 urea.5.5. Sodium concentration increased in both plasma and muscle after dehydration or following acclimatization to 400 mM/1 urea. In both situations the animals lost weight.6.6. Potassium increased in muscle fluid when acclimated to urea, but was very low in all other experimental groups.7.7. Both plasma and muscle Cl− concentrations were found to be higher in animals after dehydration or following acclimatization to 400 mM/1 urea.
Comparative Biochemistry and Physiology Part A: Physiology. 01/1983; 75(4):619-623.
[Show abstract][Hide abstract] ABSTRACT: Salamandra salamandra larvae originating from a single batch (layed by one female) were raised at different temperatures and on ion-rich or distilled water. Temperature, but not the presence or absence of ions affected growth. Larvae originating from one batch or from several batches born on the same day, were kept without food for long periods of several months in order to observe cannibalistic predation under such conditions. This phenomenon is known in natural populations of salamanders inhabitating either rain pools in rocks or permanent springs poor in aquatic life. It was found that cannibalism increased under experimental conditions proportionally to the increase in size between the larvae.
[Show abstract][Hide abstract] ABSTRACT: 1.1. Evaporative water loss and haemolymph osmolarity were studied in four scorpion species: two from mesic habitats, Scorpio maurus fuscus (Scorpionidae) and Nebo hierochonticus (Diplocentridae); and two from xeric habitats, Buthotus judaicus and Leiurus quinquestriatus (both Buthidae).2.2. Low humidity and high temperatures increased both the percentage and the rate of water loss. This effect was more pronounced in the two mesic species.3.3. Haemolymph osmolarity increased at high temperature and low humidity. In humid air osmolarity dropped only in the mesic species but remained high in the xeric species.4.4. Haemolymph osmolarity was low in winter and high in summer.
Comparative Biochemistry and Physiology Part A: Physiology. 01/1980;
[Show abstract][Hide abstract] ABSTRACT: 1.1. The response to prolactin was followed throughout ontogenesis in Salamandra salamandra and in both terrestrial and aquatic phases of Triturus vittatus.2.2. The effect of prolactin was already noticeable in 1-week old larvae and highly significant later in the 3-month old juveniles.3.3. Both phases of the newt did not show a significant response to prolactin; however, the terrestrial phase of the newt responded much more than the aquatic phase.
Comparative Biochemistry and Physiology Part A: Physiology. 01/1978; 61(2):321-324.