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Muyan Chen – One of the best experts on this subject based on the ideXlab platform.

  • Genome-Wide DNA Methylation Signatures of Sea Cucumber Apostichopus japonicus during Environmental Induced Aestivation.
    Genes, 2020
    Co-Authors: Yujia Yang, Lina Sun, Yingqiu Zheng, Muyan Chen
    Abstract:

    Organisms respond to severe environmental changes by entering into hypometabolic states, minimizing their metabolic rates, suspending development and reproduction, and surviving critical ecological changes. They come back to an active lifestyle once the environmental conditions are conducive. Marine invertebrates live in the aquatic environment and adapt to environmental changes in their whole life. Sea cucumbers and sponges are only two recently known types of marine organisms that aestivate in response to temperature change. Sea cucucucumber has become an excellent model organism for studies of environmentally-induced Aestivation by marine invertebrates. DNA methylation, the most widely considered epigenetic marks, has been reported to contribute to phenotypic plasticity in response to environmental stress in aquatic organisms. Most of methylation-related enzymes, including DNA methyltransferases, Methyl-CpG binding domain proteins, and DNA demethylases, were up-regulated during Aestivation. We conducted high-resolution whole-genome bisulfite sequencing of the intestine from sea cucucucumber at non-Aestivation and deep-Aestivation stages. Further DNA methylation profile analysis was also conducted across the distinct genomic features and entire transcriptional units. A different elevation in methylation level at internal exons was observed with clear demarcation of intron/exon boundaries during transcriptional unit scanning. The lowest methylation level occurs in the first exons, followed by the last exons and the internal exons. A significant increase in non-CpG methylation (CHG and CHH) was observed within the intron and mRNA regions in Aestivation groups. A total of 1393 genes were annotated within hypermethylated DMRs (differentially methylated regions), and 749 genes were annotated within hypomethylated DMRs. Differentially methylated genes were enriched in the mRNA surveillance pathway, metabolic pathway, and RNA transport. Then, 24 hypermethylated genes and 15 hypomethylated genes were Retrovirus-related Pol polyprotein from transposon (RPPT) genes. This study provides further understanding of epigenetic control on environmental induced hypometabolism in aquatic organisms.

  • MiR-200-3p Is Potentially Involved in Cell Cycle Arrest by Regulating Cyclin A during Aestivation in Apostichopus japonicus.
    Cells, 2019
    Co-Authors: Shanshan Wang, Muyan Chen, Yingchao Yin, Kenneth B. Storey
    Abstract:

    The sea cucucucumber (Apostichopus japonicus) has become a good model organism for studying environmentally induced Aestivation in marine invertebrates. We hypothesized that mechanisms that arrest energy-expensive cell cycle activity would contribute significantly to establishing the hypometabolic state during Aestivation. Cyclin A is a core and particularly interesting cell cycle regulator that functions in both the S phase and in mitosis. In the present study, negative relationships between miR-200-3p and AjCA expressions were detected at both the transcriptional and the translational levels during Aestivation in A. japonicus. Dual-luciferase reporter assays confirmed the targeted location of the miR-200-3p binding site within the AjCA gene transcript. Furthermore, gain- and loss-of-function experiments were conducted in vivo with sea cucumbers to verify the interaction between miR-200-3p and AjCA in intestine tissue by qRT-PCR and Western blotting. The results show that the overexpression of miR-200-3p mimics suppressed AjCA transcript levels and translated protein production, whereas transfection with a miR-200-3p inhibitor enhanced both AjCA mRNA and AjCA protein in A. japonicus intestine. Our findings suggested a potential mechanism that reversibly arrests cell cycle progression during Aestivation, which may center on miR-200-3p inhibitory control over the translation of cyclin A mRNA transcripts.

  • The potential contribution of miRNA-200-3p to the fatty acid metabolism by regulating AjEHHADH during Aestivation in sea cucumber.
    PeerJ, 2018
    Co-Authors: Muyan Chen, Kenneth B. Storey, Shanshan Wang, Xiumei Zhang
    Abstract:

    The sea cucucucumber (Apostichopus japonicus) has become a good model organism for studying environmentally-induced Aestivation by a marine inveinvertebrate more recently. In the present study, we hypothesized that miRNA-200-3p may contribute to establish rapid biological control to regulate fatty acid metabolism during a estivation. The peroxisomal bi-functional enzyme (EHHADH) is a crucial participant of the classical peroxisomal fatty acid β-oxidation pathway, the relative mRNA transcripts and protein expressions of EHHADH were analyzed in intestine from sea cucumbers experienced long-term Aestivation. Both mRNA transcripts and protein expressions of EHHADH in intestine decreased significantly during deep-Aestivation as compared with non-Aestivation controls. Analysis of the 3′ UTR of AjEHHADH showed the presence of a conserved binding site for miR-200-3p. Level of miR-200-3p showed an inverse correlation with EHHADH mRNA transcripts and protein levels in intestine, implicating miR-200-3p may directly targeted AjEHHADH by inducing the degradation of AjEHHADH mRNA in the aestivating sea cucucucumber, further dual-luciferase reporter assay validated the predicted role of miRNA-200-3p in regulating AjEHHADH. In order to further understand their regulatory mechanism, we conducted the functional experiment in vivo. The overexpression of miR-200-3p in sea cucucucumber significantly decreased mRNA and protein expression levels of AjEHHADH. Taken together, these findings suggested the potential contribution of miRNA-200-3p to the fatty acid metabolism by regulating AjEHHADH during Aestivation in sea cucucucumber.

Kenneth B. Storey – One of the best experts on this subject based on the ideXlab platform.

  • MiR-200-3p Is Potentially Involved in Cell Cycle Arrest by Regulating Cyclin A during Aestivation in Apostichopus japonicus.
    Cells, 2019
    Co-Authors: Shanshan Wang, Muyan Chen, Yingchao Yin, Kenneth B. Storey
    Abstract:

    The sea cucumber (Apostichopus japonicus) has become a good model organism for studying environmentally induced Aestivation in marine invertebrates. We hypothesized that mechanisms that arrest energy-expensive cell cycle activity would contribute significantly to establishing the hypometabolic state during Aestivation. Cyclin A is a core and particularly interesting cell cycle regulator that functions in both the S phase and in mitosis. In the present study, negative relationships between miR-200-3p and AjCA expressions were detected at both the transcriptional and the translational levels during Aestivation in A. japonicus. Dual-luciferase reporter assays confirmed the targeted location of the miR-200-3p binding site within the AjCA gene transcript. Furthermore, gain- and loss-of-function experiments were conducted in vivo with sea cucumbers to verify the interaction between miR-200-3p and AjCA in intestine tissue by qRT-PCR and Western blotting. The results show that the overexpression of miR-200-3p mimics suppressed AjCA transcript levels and translated protein production, whereas transfection with a miR-200-3p inhibitor enhanced both AjCA mRNA and AjCA protein in A. japonicus intestine. Our findings suggested a potential mechanism that reversibly arrests cell cycle progression during Aestivation, which may center on miR-200-3p inhibitory control over the translation of cyclin A mRNA transcripts.

  • The potential contribution of miRNA-200-3p to the fatty acid metabolism by regulating AjEHHADH during Aestivation in sea cucumber.
    PeerJ, 2018
    Co-Authors: Muyan Chen, Kenneth B. Storey, Shanshan Wang, Xiumei Zhang
    Abstract:

    The sea cucumber (Apostichopus japonicus) has become a good model organism for studying environmentally-induced Aestivation by a marine invertebrate more recently. In the present study, we hypothesized that miRNA-200-3p may contribute to establish rapid biological control to regulate fatty acid metabolism during a estivation. The peroxisomal bi-functional enzyme (EHHADH) is a crucial participant of the classical peroxisomal fatty acid β-oxidation pathway, the relative mRNA transcripts and protein expressions of EHHADH were analyzed in intestine from sea cucumbers experienced long-term Aestivation. Both mRNA transcripts and protein expressions of EHHADH in intestine decreased significantly during deep-Aestivation as compared with non-Aestivation controls. Analysis of the 3′ UTR of AjEHHADH showed the presence of a conserved binding site for miR-200-3p. Level of miR-200-3p showed an inverse correlation with EHHADH mRNA transcripts and protein levels in intestine, implicating miR-200-3p may directly targeted AjEHHADH by inducing the degradation of AjEHHADH mRNA in the aestivating sea cucumber, further dual-luciferase reporter assay validated the predicted role of miRNA-200-3p in regulating AjEHHADH. In order to further understand their regulatory mechanism, we conducted the functional experiment in vivo. The overexpression of miR-200-3p in sea cucumber significantly decreased mRNA and protein expression levels of AjEHHADH. Taken together, these findings suggested the potential contribution of miRNA-200-3p to the fatty acid metabolism by regulating AjEHHADH during Aestivation in sea cucumber.

  • A potential antiapoptotic regulation: The interaction of heat shock protein 70 and apoptosis-inducing factor mitochondrial 1 during heat stress and Aestivation in sea cucumber.
    Journal of experimental zoology. Part A Ecological and integrative physiology, 2018
    Co-Authors: Shasha Wang, Kenneth B. Storey, Muyan Chen, Tianming Wang
    Abstract:

    The sea cucucucumber (Apostichopus japonicus) has become a good model organism for studying environmentally induced Aestivation in marine invertebrates. A characteristic feature of Aestivation in this species is the degeneration of the intestine. In the current study, we hypothesized that energy conservation and cytoprotective strategies need to be coordinated in the intestine to ensure long-term survival during Aestivation, and there was potential relationship between heat shock protein 70 (HSP70) and apoptosis-inducing factor mitochondrial 1 (AIFM1) during extreme environmental stress. AIFM1 is a bifunctional flavoprotein that is involved in the caspase-independent activation of apoptosis. The gene and protein expression profiles of AjAIFM1 and AjHSP70 in intestinal tissue during Aestivation were analyzed and results showed an inverse correlation between them, AjAIFM1 being suppressed during Aestivation whereas AjHSP70 was strongly upregulated. Comparable responses were also seen when intestinal cells were isolated and analyzed in vitro for responses to heat stress at 25°C (a water temperature typical during Aestivation), compared with 15°C control cells. Combined with co-immunoprecipitation studies in vivo and in vitro, our results suggested that AjHSP70 protein may have potential interaction with AjAIFM1. To determine the influence of heat stress on apoptotic rate of intestinal cells, we also assessed the DNA fragmentation by terminal deoxynucleotide transferase-mediated dUTP nick-end labeling assay, and results also supported a potential antiapoptotic response in sea cucucucumber during heat stress. This type of cytoprotective mechanism could be used to preserve the existing cellular components during long-term Aestivation in sea cucucucumber.

Shit F Chew – One of the best experts on this subject based on the ideXlab platform.

  • Molecular characterization of myostatin from the skeletal muscle of the African lungfish, Protopterus annectens, and changes in its mRNA and protein expression levels during three phases of Aestivation.
    Journal of comparative physiology. B Biochemical systemic and environmental physiology, 2017
    Co-Authors: Jasmine L. Y. Ong, Wai P Wong, Kum C Hiong, You R. Chng, Biyun Ching, Xiu L. Chen, Shit F Chew
    Abstract:

    African lungfishes can aestivate and remain torpid without food and water for years, but disuse muscle atrophy is not prominent during Aestivation. This study aimed to clone myostatin (mstn/Mstn), a factor associated with disuse muscle atrophy in mammals, from the skeletal muscle of the African lungfish Protopterus annectens, and to determine its mRNA expression level and protein abundance therein during the induction, maintenance, and arousal phases of Aestivation. The complete coding cDNA sequence of mstn comprised 1128 bp, encoding for 376 amino acids with an estimated molecular mass of 42.9 kDa. It was grouped together with Mstn/MSTN of coelacanth and tetrapods in a clade separated from teleost Mstn. After 6 days (the induction phase) of Aestivation, the mstn transcript level in the muscle increased significantly, while the protein abundance of Mstn remained comparable to the control. Following that, a significant increase in the expression levels of mstn/Mstn occurred on day 12 (the early maintenance phase) of Aestivation. After 6 months of Aestivation (the prolonged maintenance phase), the expression levels of mstn/Mstn returned to control levels, indicating the possible impediment of a drastic increase in muscle degradation to prevent muscle atrophy. During 1-3 days of arousal from Aestivation, the expression levels of mstn/Mstn in the muscle remained comparable to the control. Hence, tissue reconstruction/regeneration of certain organs might not involve the mobilization of amino acids from the muscle during the early arousal. These results provide insights into how aestivating P. annectens regulates the expression of mstn/Mstn possibly to ameliorate disuse muscle atrophy.

  • molecular characterization of aquaporin 1 and aquaporin 3 from the gills of the african lungfish protopterus annectens and changes in their branchial mrna expression levels and protein abundance during three phases of Aestivation
    Frontiers in Physiology, 2016
    Co-Authors: You R. Chng, Wai P Wong, Kum C Hiong, Shit F Chew, Jasmine L. Y. Ong, Biyun Ching, Xiu L. Chen, Siew Hong Lam
    Abstract:

    African lungfishes can undergo long periods of Aestivation on land during drought. During Aestivation, lungfishes are confronted with desiccation and dehydration, and their gills become non-functional and covered with a thick layer of dried mucus. Aquaporins (Aqps) are a superfamily of integral membrane proteins which generally facilitate the permeation of water through plasma membranes. This study aimed to obtain the complete cDNA coding sequences of aqp1 and aqp3 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. Dendrogramic analyses of the deduced Aqp1 and Aqp3 amino acid sequences of P. annectens revealed their close relationships with those of Latimeria chalumnae and tetrapods. During the induction phase, there were significant decreases in the transcript levels of aqp1 and aqp3 in the gills of P. annectens, but the branchial Aqp1 and Aqp3 protein abundance remained unchanged. As changes in transcription may precede changes in translation, this could be regarded as an adaptive response to decrease the protein abundance of Aqp1 and Aqp3 in the subsequent maintenance phase of Aestivation. As expected, the branchial transcript levels and protein abundance of aqp1/Aqp1 and aqp3/Aqp3 were significantly down-regulated during the maintenance phase, probably attributable to the shutdown of branchial functions and the cessation of volume regulation of branchial epithelial cells. Additionally, these changes could reduce the loss of water through branchial epithelial surfaces, supplementing the anti-desiccating property of the dried mucus. Upon arousal, it was essential for the lungfish to restore branchial functions. Indeed, the protein abundance of Aqp1 recovered partially, with complete recovery of mRNA expression level and protein abundance of Aqp3, in the gills of P. annectens. These results provide insights into how P. annectens regulates branchial Aqp expression to cope with desiccation and rehydration during different phases of Aestivation.

  • Aestivation induces changes in transcription and translation of coagulation factor ii and fibrinogen gamma chain in the liver of the african lungfish protopterus annectens
    The Journal of Experimental Biology, 2015
    Co-Authors: Kum C Hiong, Wai Peng Wong, Shit F Chew, Yuen K Ip
    Abstract:

    ABSTRACT This study aimed to sequence and characterize two pro-coagulant genes, coagulation factor II ( f2 ) and fibrinogen gamma chain ( fgg ), from the liver of the African lungfish Protopterus annectens , and to determine their hepatic mRNA expression levels during three phases of Aestivation. The protein abundance of F2 and Fgg in the liver and plasma was determined by immunoblotting. The results indicated that F2 and Fgg of P. annectens were phylogenetically closer to those of amphibians than those of teleosts. Three days of Aestivation resulted in an up-regulation in the hepatic fgg mRNA expression level, while 6 days of Aestivation led to a significant increase (3-fold) in the protein abundance of Fgg in the plasma. Hence, there could be an increase in the blood-clotting ability in P. annectens during the induction phase of Aestivation. By contrast, the blood-clotting ability in P. annectens might be reduced in response to decreased blood flow and increased possibility of thrombosis during the maintenance phase of Aestivation, as 6 months of Aestivation led to significant decreases in mRNA expression levels of f2 and fgg in the liver. There could also be a decrease in the export of F2 and Fgg from the liver to the plasma so as to avert thrombosis. Three to 6 days after arousal from 6 months of Aestivation, the protein abundance of F2 and Fgg recovered partially in the plasma of P. annectens ; a complete recovery of the transcription and translation of f2 /F2 in the liver might occur only after refeeding.

Hongsheng Yang – One of the best experts on this subject based on the ideXlab platform.

  • differential gene expression in the respiratory tree of the sea cucumber apostichopus japonicus during Aestivation
    Marine Genomics, 2014
    Co-Authors: Ye Zhao, Kenneth B. Storey, Hongsheng Yang, Muyan Chen
    Abstract:

    Sea cucumbers, Apostichopus japonicus, experience seasonally high water temperatures during the summer months and enter Aestivation to survive. Aestivation is characterized by strong metabolic rate depression which is supported by a series of strategies including reorganizing metabolic processes, suppressing cell functions, enhancing cytoprotective mechanisms, and altered gene expression. The respiratory tree tissue of the sea cucucucumber is an excellent material for studying Aestivation, undergoing obvious atrophy during Aestivation. The present study analyzed the global gene expression profile of respiratory tree tissue of A. japonicus during Aestivation by constructing and screening three libraries representing key stages of Aestivation: non-Aestivation (NA), deep-Aestivation (DA), and arousal from Aestivation (M) using RNA-seq. A total of 1240, 1184 and 303 differentially expressed genes (DEGs) were identified following the criteria of [log(2) ratiol >= 1 and FDR <= 0.001 in comparisons of DA vs. NA, AA vs. NA and DA vs. AA. A set of respiratory tree specific DEGs was identified the first time and, in addition, common DEGs that were responsive to Aestivation in both respiratory tree and intestine were identified. Functional analysis of DEGs was further performed by GO enrichment analysis and respiratory tree specific GO terms were screened out and provide interesting hints for further studies of the molecular regulation of Aestivation in A. japonicus. (c) 2014 Elsevier B.V. All rights reserved.

  • DNA methylation levels analysis in four tissues of sea cucumber Apostichopus japonicus based on fluorescence-labeled methylation-sensitive amplified polymorphism (F-MSAP) during Aestivation.
    Comparative biochemistry and physiology. Part B Biochemistry & molecular biology, 2014
    Co-Authors: Ye Zhao, Kenneth B. Storey, Muyan Chen, Lina Sun, Hongsheng Yang
    Abstract:

    DNA methylation plays an important role in regulating transcriptional change in response to environmental stimuli. In the present study, DNA methylation levels of tissues of the sea cucucucumber Apostichopus japonicus were analyzed by the fluorescence-labeled methylation-sensitive amplified polymorphism (F-MSAP) technique over three stages of the Aestivation cycle. Overall, a total of 26,963 fragments were amplified including 9112 methylated fragments among four sea cucucucumber tissues using 18 pairs of selective primers. Results indicated an average DNA methylation level of 33.79% for A. japonicus. The incidence of DNA methylation was different across tissue types in the non-Aestivation stage: intestine (30.16%), respiratory tree (27.61%), muscle (27.94%) and body wall (56.25%). Our results show that hypermethylation accompanied deep-Aestivation in A. japonicus, which suggests that DNA methylation may have an important role in regulating global transcriptional suppression during Aestivation. Further analysis indicated that the main DNA modification sites were focused on intestine and respiratory tree tissues and that full-methylation but not hemi-methylation levels exhibited significant increases in the deep-Aestivation stage. (C) 2014 Elsevier Inc. All rights reserved.

  • Differential gene expression in the respiratory tree of the sea cucumber Apostichopus japonicus during Aestivation.
    Marine genomics, 2014
    Co-Authors: Ye Zhao, Kenneth B. Storey, Hongsheng Yang, Muyan Chen
    Abstract:

    Sea cucumbers, Apostichopus japonicus, experience seasonally high water temperatures during the summer months and enter Aestivation to survive. Aestivation is characterized by strong metabolic rate depression which is supported by a series of strategies including reorganizing metabolic processes, suppressing cell functions, enhancing cytoprotective mechanisms, and altered gene expression. The respiratory tree tissue of the sea cucucucumber is an excellent material for studying Aestivation, undergoing obvious atrophy during Aestivation. The present study analyzed the global gene expression profile of respiratory tree tissue of A. japonicus during Aestivation by constructing and screening three libraries representing key stages of Aestivation: non-Aestivation (NA), deep-Aestivation (DA), and arousal from Aestivation (AA) using RNA-seq. A total of 1240, 1184 and 303 differentially expressed genes (DEGs) were identified following the criteria of |log2 ratio|≥1 and FDR≤0.001 in comparisons of DA vs. NA, AA vs. NA and DA vs. AA. A set of respiratory tree specific DEGs was identified the first time and, in addition, common DEGs that were responsive to Aestivation in both respiratory tree and intestine were identified. Functional analysis of DEGs was further performed by GO enrichment analysis and respiratory tree specific GO terms were screened out and provide interesting hints for further studies of the molecular regulation of Aestivation in A. japonicus.

Craig E Franklin – One of the best experts on this subject based on the ideXlab platform.

  • enzyme activity in the aestivating green striped burrowing frog cyclorana alboguttata
    Journal of Comparative Physiology B-biochemical Systemic and Environmental Physiology, 2010
    Co-Authors: Beth Mantle, Nicholas J Hudson, Helga Guderley, Craig E Franklin
    Abstract:

    Green-striped burrowing frogs (Cyclorana alboguttata) can depress their resting metabolism by more than 80% during Aestivation. Previous studies have shown that this species is able to withstand long periods of immobilisation during Aestivation while apparently maintaining whole muscle mass and contractile performance. The aim of this study was to determine the effect of prolonged Aestivation on the levels of metabolic enzymes (CCO, LDH and CS) in functionally distinct skeletal muscles (cruralis, gastrocnemius, sartorius, iliofibularis and rectus abdominus) and liver of C. alboguttata. CS activity was significantly reduced in all tissues except for the cruralis, gastrocnemius and the liver. LDH activity was significantly reduced in the sartorius and rectus abdominus, but remained at control (active) levels in the other tissues. CCO activity was significantly reduced in the gastrocnemius and rectus abdominus, and unchanged in the remaining tissues. Muscle protein was significantly reduced in the sartorius and iliofibularis during Aestivation, and unchanged in the remaining muscles. The results suggest that the energy pathways involved in the production and consumption of ATP are remodelled during prolonged Aestivation but selective. Remodelling and subsequent down-regulation of metabolic activity seem to target the smaller non-jumping muscles, while the jumping muscles retain enzyme activities at control levels during Aestivation. These results suggest a mechanism by which aestivating C. alboguttata are able to maintain metabolic depression while ensuring that the functional capacity of critical muscles is not compromised upon emergence from Aestivation.

  • metabolic depression during Aestivation in cyclorana alboguttata
    Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2009
    Co-Authors: Sara M. Kayes, Rebecca L Cramp, Craig E Franklin
    Abstract:

    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 metametabolism 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 inteintestine 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. (C) 2009 Elsevier Inc. All rights reserved.

  • Ups and downs of intestinal function with prolonged fasting during Aestivation in the burrowing frog, Cyclorana alboguttata
    Journal of Experimental Biology, 2009
    Co-Authors: Rebecca L Cramp, Sara M. Kayes, Edward A Meyer, Craig E Franklin
    Abstract:

    Although green striped burrowing frogs (Cyclorana alboguttata) experience large reductions in the mass and absorptive surface area of the small intestine (SI) during Aestivation, little is known about how this may affect the functional capacity of the SI. We examined changes in the function (l-proline uptake rate and capacity) and metabolism of the SI (in vitro oxygen consumption, Na(+)/K(+)-ATPase activity and abundance) of C. alboguttata following 6 months of Aestivation. l-Proline uptake rate was significantly higher in aestivating frogs, but overall uptake capacity was lower than in active frogs. Total SI oxygen consumption rate (V(O(2))) was also lower in aestivating frogs, despite no difference in mass-specific V(O(2)). The proportion of intestinal V(O(2)) associated with Na(+)/K(+)-ATPase activity and protein synthesis was equivalent between active and aestivating frogs, suggesting these processes were unaffected by Aestivation. Indeed, the activity of Na(+)/K(+)-ATPase transporters in the SI of aestivating frogs was not different from that of active animals. Aestivating frogs maintained Na(+)/K(+)-ATPase activity, despite experiencing a reduction in the density of Na(+)/K(+)-ATPase transporters, by increasing the molecular activity of the remaining pumps to 2-3 times that of active frogs. These results show that functionality of the SI is maintained at the cellular level, potentially facilitating the reclamation of nutrients from the intestinal lumen while in Aestivation. Despite this, the functional capacity of the SI in aestivating C. alboguttata is significantly reduced due to a reduction in tissue mass, helping frogs to conserve energy while in Aestivation.