Effect Of Aestivation Research Articles

Effects of aestivation on survival of Bithynia siamensis goniomphalos snails and the infection of Opisthorchis viverrini in the irrigation area of wet- and dry-season rice paddy

The snail Bithynia siamensis goniomphalos acts as the first intermediate host of the human liver fluke, Opisthorchis viverrini, a major cause of cholangiocarcinoma in Northeast Thailand. In this study, we investigated host-parasite interactions in wet- and dry-season rice paddy plantation. The snails that aestivated through 4-month-dried period after rice harvest had average mortality rate of 36.45% and monthly increasing from 17.76% to 54.57%. Surprisingly, at depths greater than 5 cm experienced a higher mortality rate than upper level. Average mortality rate at the depth more than 5 cm, was 42.97%. In the initial month of aestivation, mortality rate of 0–5 and 5–10 cm depth was 9.13% and 26.39% then increase to 57.58% and 51.97%, respectively in the last 4th month. The average prevalence O. viverrini infection in snails during the study period was 0.44%. The highest prevalence of O. viverrini infection was found in the cool dry and wet season. The odds of O. viverrini infection in female snails and large snails were higher relative to male snails and medium-sized snails. The physicochemical factors involved in increased prevalence of O. viverrini infection in snail hosts were mean daily air temperature and average monthly rainfall. Short aestivation period made lower mortality in irrigation area than the previous report of non-irrigation area, that is, the aestivation is one of snail population control.

Molecular characterization of three Rhesus glycoproteins from the gills of the African lungfish, Protopterus annectens, and effects of aestivation on their mRNA expression levels and protein abundance.

African lungfishes are ammonotelic in water. They can aestivate for long periods on land during drought. During aestivation, the gills are covered with dried mucus and ammonia excretion ceases. In fishes, ammonia excretion through the gills involves Rhesus glycoproteins (RhGP/Rhgp). This study aimed to obtain the complete cDNA coding sequences of rhgp from the gills of Protopterus annectens, and to determine their branchial mRNA and protein expression levels during the induction, maintenance and arousal phases of aestivation. Three isoforms of rhgp (rhag, rhbg and rhcg) were obtained in the gills of P. annectens. Their complete cDNA coding sequences ranged between 1311 and 1398 bp, coding for 436 to 465 amino acids with estimated molecular masses between 46.8 and 50.9 kDa. Dendrogramic analyses indicated that Rhag was grouped closer to fishes, while Rhbg and Rhcg were grouped closer to tetrapods. During the induction phase, the protein abundance of Rhag, but not its transcript level, was down-regulated in the gills, suggesting that there could be a decrease in the release of ammonia from the erythrocytes to the plasma. Furthermore, the branchial transcript levels of rhbg and rhcg decreased significantly, in preparation for the subsequent shutdown of gill functions. During the maintenance phase, the branchial expression levels of rhag/Rhag, rhbg/Rhbg and rhcg/Rhcg decreased significantly, indicating that their transcription and translation were down-regulated. This could be part of an overall mechanism to shut down branchial functions and save metabolic energy used for transcription and translation. It could also be regarded as an adaptive response to stop ammonia excretion. During the arousal phase, it is essential for the lungfish to regain the ability to excrete ammonia. Indeed, the protein abundance of Rhag, Rhbg and Rhcg recovered to the corresponding control levels after 1 day or 3 days of recovery from 6 months of aestivation.

Molecular characterization of betaine-homocysteine methyltransferase 1 from the liver, and effects of aestivation on its expressions and homocysteine concentrations in the liver, kidney and muscle, of the African lungfish, Protopterus annectens.

Homocysteine accumulation has numerous deleterious effects, and betaine-homocysteine S-methyltransferase (BHMT) catalyses the synthesis of methionine from homocysteine and betaine. This study aimed to determine homocysteine concentrations, and mRNA expression levels and protein abundances of bhmt1/Bhmt1 in the liver, kidney and muscle of the African lungfish, Protopterus annectens, during the induction (6 days), maintenance (6 months) or arousal (3 days after arousal) phase of aestivation. The homocysteine concentration decreased significantly in the liver of P. annectens after 6 days or 6 months of aestivation, but it returned to the control level upon arousal. By contrast, homocysteine concentrations in the kidney and muscle remained unchanged during the three phases of aestivation. The complete coding cDNA sequence of bhmt1 from P. annectens consisted of 1236 bp, coding for 412 amino acids. The Bhmt1 from P. annectens had a close phylogenetic relationship with those from tetrapods and Callorhinchus milii. The expression of bhmt1 was detected in multiple organs/tissues of P. annectens, and this is the first report on the expression of bhmt1/Bhmt1 in animal skeletal muscle. The mRNA and protein expression levels of bhmt1/Bhmt1 were up-regulated in the liver of P. annectens during the induction and maintenance phases of aestivation, possibly to regulate the hepatic homocysteine concentration. The significant increase in hepatic Bhmt1 protein abundance during the arousal phase could be a response to increased cellular methylation for the purpose of tissue reconstruction. Unlike the liver, Bhmt1 expression in the kidney and muscle of P. annectens was regulated translationally, and its up-regulation could be crucial to prevent homocysteine accumulation.

Comparative evaluation of haemagglutination potential of haemolymph from two species of giant African land snails (Archachatina marginata and Achatina achatina)

A comparative study was conducted to evaluate haemagglutination potential in the haemolymph of two species of giant African land snails (Archachatina marginata and Achatina achatina). Three liveweight groups of snails (<100 g, 101–150 g and >150 g) were used with 4 replicates per liveweight per species for haemagglutination assay (HA). The effect of aestivation on haemagglutination potential was also evaluated. Erythrocytes (2%) from cattle, sheep, goat and chicken were used for HA assay. Results showed that agglutinin-like substances that agglutinate erythrocytes of sheep, goat, cattle and chicken were present in the haemolymph of the two species of giant African land snails. Effect of species was found to be significant (P < 0.001) on haemagglutination titre. Haemolymph of A. marginata, had higher haemagglutination titre than that of A. achatina across the three liveweight groups used in this study. Snail liveweight had no significant effect (P > 0.05) on agglutinin content of the haemolymph in both species. Agglutination level depended on the source of erythrocyte used. Sheep erythrocyte recorded the highest haemagglutination titre, followed by goat, cattle, and chicken in that order. To our knowledge, this is the first evidence that Giant African land snails (GALS) haemolymph contain agglutinins as previously reported for Helix species. This evidence may be the basis for its survivability in the wild and thus establish the use of GALS for African herbal medicinal applications.

Biochemical evaluation of aestivation and starvation in two snail species

There is resurgence in incidence of schistosomiasis in Nigeria with attendant socio-economic and health impact. The agents transmitting this disease are theBulinus snails which employ aestivation to survive conditions of unfavourable weather such as lack of food and water. The mechanism of aestivation under aridity and drought is not clear. This study therefore investigated the effects of aestivation and starvation on endogenous metabolic reserves in haemolymph of two snail species namely: Bulinus globosus (Morelet) and Bulinus rohlfsi (Clessin). Aestivation, starvation and control experiments were set up for 30 days in the laboratory by placing three groups of snails collected from Oyan dam, Abeokuta in standard aestivation slope (30 B. globosus and 19 B. rohlfsi), aquarium (30 B. globosus and 23 B. rohlfsi) and control slope which had 20 B. globosus and 15 B. rohlfsi. Aestivation and control slopes contained water and mixture of sand and clay (3:1), while aquarium contained water only for starvation. All the snails were fed on lettuce ad libitum for 28 days during which water was completely drained out in the aestivation slope. The aestivation slope and aquarium were left for another 30 days without lettuce. Snails were thereafter sacrificed and haemolymph biochemical parameters were assayed. In aestivating and starving B. globosus, haemolymph creatinine, urea, total protein, glucose, alanine transferases (ALT) and aspartate transferases (AST) were significantly decreased, while haemolymph total cholesterol, triglyceride and a-amylase concentrations and activity increased significantly (p < 0.05). In B. rohlfsi, creatinine, urea, ALT and AST were significantly decreased when compared with controls (p < 0.05). B. globosus and B. rohlfsipossess ability to survive unfavourable conditions by economical utilization of stored metabolites, thus enabling them to carry infection from one season to the next. Our findings suggest that B. globosus is a better aestivator than B. rohlfsi. Key words: Aestivation, enzymes, Bulinus globosus, Bulinus rohlfsi, schistosomiasis.

Metabolic depression during aestivation in Cyclorana alboguttata

The green striped burrowing frog, Cyclorana alboguttata, spends, on average, nine to ten months of every year in aestivation. Recently, C. alboguttata has been the focus of much investigation regarding the physiological processes involved in aestivation, yet our understanding of this frog's capacity to metabolically depress remains limited. This study aimed to extend our current knowledge of metabolic depression during aestivation in C. alboguttata. C. alboguttata reduced whole animal metabolism by 82% within 5 weeks of aestivation. The effects of aestivation on mass specific in vitro tissue metabolic rate (VO 2) varied among individual organs, with muscle and liver slices showing significant reductions in metabolism; kidney VO 2 was elevated and there was no change in the VO 2 of small intestine tissue slices. Organ size was also affected by aestivation, with significant reductions in the mass of all tissues, except the gastrocnemius. These reductions in organ size, combined with changes in mass specific VO 2 of tissue slices, resulted in further energy savings to aestivating animals. This study shows that C. alboguttata is capable of selectively down- or up-regulating individual tissues, using both changes in metabolic rate and morphology. This strategy allows maximal energy savings during aestivation without compromising organ functionality and survival at arousal.

Metabolic depression during aestivation does not involve remodelling of membrane fatty acids in two Australian frogs

Changes in membrane lipid composition (membrane remodelling) have been associated with metabolic depression in some aestivating snails but has not been studied in aestivating frogs. This study examined the membrane phospholipid composition of two Australian aestivating frog species Cyclorana alboguttata and Cyclorana australis. The results showed no major membrane remodelling of tissue in either frog species, or in mitochondria of C. alboguttata due to aestivation. Mitochondrial membrane remodelling was not investigated in C. australis. Where investigated in C. alboguttata, total protein and phospholipid content, and citrate synthase (CS) and cytochrome c oxidase (CCO) activities in tissues and mitochondria mostly did not change with aestivation in liver. In skeletal muscle, however, CS and CCO activities, mitochondrial and tissue phospholipids, and mitochondrial protein decreased with aestivation. These decreases in muscle indicate that skeletal muscle mitochondrial content may decrease during aestivation. Na(+)K(+)ATPase activity of both frog species showed no effect of aestivation. In C. alboguttata different fat diets had a major effect on both tissue and mitochondrial phospholipid composition indicating an ability to remodel membrane composition that is not utilised in aestivation. Therefore, changes in lipid composition associated with some aestivating snails do not occur during aestivation in these Australian frogs.

Prolonged aestivation causes little change in skeletal muscle morphology or contractile performance in the anuran Cyclorana aloboguttata

Prolonged immobilisation or unloading of skeletal muscle causes muscle disuse atrophy that is characterised by a reduction in muscle cross-sectional area and compromised locomotory function. Animals that enter seasonal dormancy, such as hibernators and aestivators, exhibit a decline in metabolic and locomotor activity that is correlated with seasonal fluctuations in temperature and resource availability. As such, hibernators and aestivators provide a fascinating natural model for investigating muscle atrophy associated with disuse (see review by Hudson and Franklin, 2002). Previous research has also indicated that aerobic muscles should be more susceptible to muscle disuse atrophy than glycolytic muscles as there is a greater change in daily activity. We investigated the effect of aestivation on ileofibularis (relatively slow twitch) and sartorius (relatively fast twitch) muscle morphology and contractile function in C. alboguttata over a longer, more ecologically relevant time-frame of nine months. We found that whole muscle mass, muscle cross-sectional area, fibre number and proportions of fibre types remained unchanged after prolonged disuse. There were significant reductions in ileofibularis fibre cross-sectional area (> 35%) and sartorius fibre density (44%) and significant slowing of isometric kinetics. However, the work loop power output of both muscles from nine-month aestivating C. alboguttata were maintained at control levels. The results from this study strongly support the supposition that C. alboguttata is able to inhibit the effects of atrophy during disuse in both sartorius and ileofibularis muscles.

EFFECTS OF AESTIVATION AND STARVATION ON THE NEUTRAL LIPID AND PHOSPHOLIPID CONTENT OF BIOMPHALARIA GLABRATA INFECTED WITH SCHISTOSOMA MANSONI

The effects of aestivation or starvation on the neutral lipid and phospholipid content of Biomphalaria glabrata patently infected with Schistosoma mansoni were determined by high-performance thin-layer chromatography-densitometry. Infected-aestivated snails were maintained in a moist chamber at 24 +/- 1 C and a relative humidity of 98 +/- 1%. Infected-starved snails were maintained in artificial spring water (ASW) at 23 +/- 1 C without exogenous food. Infected snails (the controls) were maintained in ASW at 23 +/- 1 C and fed lettuce ad libitum. The 3 groups were maintained in the laboratory for 7 days, and then the lipids from the digestive gland-gonad complex (DGG) were extracted and analyzed by class. Infected-aestivated snails exhibited greater mortality rate and weight loss after 7 days than did the infected-starved snails. The steryl ester concentration in the infected-starved snails was significantly increased (P = 0.010) compared with the controls but not compared with infected-aestivated snails; the concentration of phosphatidylcholine in infected-aestivated snails was significantly decreased (P = 0.007) compared with the controls but not when compared with the infected-starved snails. Aestivation or starvation had a significant effect on the concentration of certain lipid classes in the DGG of B. glabrata infected with S. mansoni.

Effect of aestivation of Biomphalaria pfeifferi on the survival and infectivity of Schistosoma mansoni cercariae

Schistosoma mansoni cercariae from post-aestivated Biomphalaria pfeifferi remain motile for 20 hours after release. Thereafter, their activity decreases with age. The difference in mortality rate of cercariae from aestivated and non-aestivated B. pfeifferi studied here proved to be statistically significant (P<0.05) within the first 10 hours of the experimental period. Results of the percentage recovery of worms from different mouse organs infected with cercariae from aestivated and non-aestivated snails varied. The two main organs infected were the liver and intestine. In conclusion, the penetration, migration and maturation of cercariae into adult worms were not affected by the aestivation of B. pfeifferi.

Schistosoma mansoni: effect of aestivation on the intra-molluscan stages and the survival rate of infected Biomphalaria pfeifferi.

Following exposure to the miracidia of Schistosoma mansoni, Biomphalaria pfeifferi were induced to aestivate immediately ('0 h') or on days 7, 14 or 21 post-infection and then re-activated at various times. The proportions of snails found to be alive at weekly intervals after re-activation were found to be related to the length of time the snails had spent between infection and aestivation (I-A), varying from 100% (0 h) to 5% (21 days). The mean numbers of cercariae produced by the snails after re-activation also varied with I-A, being highest in those that aestivated immediately post-infection, and cercarial development was delayed by prolonged desiccation of the infected snails, the intra-molluscan development of S. mansoni is affected by the aestivation of the snail host.

The effects of aestivation on the catalytic and regulatory properties of pyruvate kinase from Helix aspersa

1. 1. Pyruvate kinase was partially purified from the foot, mantle, and digestive gland of active and aestivating snails. 2. 2. At pH 7.0 the apparent K m values for phosphoenolpyruvate (PEP) were 0.064 mmol/l for the enzyme from foot and 0.071 mmol/l for the enzyme from mantle; those for ADP were 0.35 mmol/l for the foot enzyme and 0.33 mmol/l for the mantle enzyme. 3. 3. Both enzymes were inhibited by alanine, and this could be reversed by fructose 1,6-bisphosphate (FBP), although FBP alone was a weak activator. 4. 4. Decreasing the pH to 6.5 markedly increased the inhibition by alanine and reduced the response to FBP. 5. 5. The enzymes from these tissues of aestivating snails showed a small decrease in their affinity for PEP and a small increase in the effectiveness of alanine as an inhibitor. 6. 6. These changes are indicative of a down-regulation of this enzyme which is consistent with the observations in other species during metabolic depression. 7. 7. In contrast the enzyme from the digestive gland of active animals showed sigmoidal saturation kinetics for PEP with a S 0.5 of 1.2 mmol/l, but had a markedly higher affinity for PEP, S 0.5 = 0.20 mmol/l during aestivation. This may be indicative of other metabolic changes occurring in the digestive gland.

Aestivation (Summer Diapause) in Hypera postica (Coleoptera: Curculionidae). I. Effect of Aestivation, Photoperiods, and Diet on Total Fatty Acids1

Total fatty acids of the adult alfalfa weevil, Hypera postica (Gyllenhal), collected in South Carolina were examined by gas chromatography. Seven acids accounted for approximately 98% of the total: myristic (14:0), palmitic (18:0), palmitoleic (16:1), stearic (18:0), oleic (18:1), linoleic (18:2) and linolenic (18:3). Based on analyses of pre- and postaestivating populations, the 3 principal characteristics noted during this period of reduced metabolism were a decrease in oleic acid, a decrease in monounsaturates, and an increase in polyunsaturates. Little evidence of any larval photoperiodic influence (8 or 16 hours) upon the new adult's fatty-acid composition was observed. However, weevils clearly mirrored the fatty-acid composition of the food source—artificial diet with high linoleic and fresh alfalfa with high linolenic acid.

The Effect of Aestivation on Sexual Maturation in the Female Alfalfa Weevil (Hypera postica)1

The development of sex organs in female alfalfa weevils (Hypera postica (Gyllential)) during aestivation was studied. Females were dissected at monthly intervals to study the progressive stages of sexual maturation. Weevils that emerged from cocoons in way entered into an apparent diapause stage until October. Morphological growth of the female sex organs was considerably arrested during diapause, and sexual maturity was not reached until November 23. Adults which emerged in September did not diapause and the females also attained sexual maturity on November 23. Diapausing weevils required 6 months to mature whereas nondiapausing weevils reached maturity 81 days after emerging from cocoons.