1
|
Ip YK, Leong CWQ, Boo MV, Wong WP, Lam SH, Chew SF. Evidence for the involvement of branchial Vacuolar-type H +-ATPase in the acidification of the external medium by the West African lungfish, Protopterus annectens, exposed to ammonia-loading conditions. Comp Biochem Physiol A Mol Integr Physiol 2022; 273:111297. [PMID: 35987338 DOI: 10.1016/j.cbpa.2022.111297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 08/09/2022] [Accepted: 08/10/2022] [Indexed: 10/31/2022]
Abstract
African lungfishes are obligatory air-breathers with exceptionally high environmental ammonia tolerance. They can lower the pH of the external medium during exposure to ammonia-loading conditions. This study aimed to demonstrate the possible involvement of branchial vacuolar-type H+-ATPase (Vha) in the ammonia-induced acidification of the external medium by the West African lungfish, Protopterus annectens, and to examine whether its capacity to acidify the medium could be augmented after exposure to 100 mmol l-1 NH4Cl for six days. Two full coding cDNA sequences of Vha subunit B (atp6v1b), atp6v1b1 and atp6v1b2, were obtained from the internal gills of P. annectens. The sequence of atp6v1b1 comprised 1548 bp, encoding 515 amino acids (57.4 kDa), while that of atp6v1b2 comprised 1536 bp, encoding 511 amino acids (56.6 kDa). Using a custom-made antibody reactive to both isoforms, immunofluorescence microscopy revealed the collective localization of Atp6v1b (atp6v1b1 and atp6v1b2) at the apical or the basolateral membrane of two different types of branchial Na+/K+-ATPase-immunoreactive ionocyte. The ionocytes labelled apically with Atp6v1b presumably expressed Atp6v1b1 containing a PDZ-binding domain, indicating that the apical Vha was positioned to transport H+ to the external medium. The expression of Atp6v1b was regulated post-transcriptionally, as the protein abundance of Atp6v1b and Vha activity increased significantly in the gills of fish exposed to 100 mmol l-1 NH4Cl for six days. Correspondingly, the fish exposed to ammonia had a greater capacity to acidify the external medium, presumably to decrease the ratio of [NH3] to [NH4+] in order to reduce the influx of exogenous NH3.
Collapse
Affiliation(s)
- Yuen K Ip
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore.
| | - Charmaine W Q Leong
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Mel V Boo
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Wai P Wong
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Siew H Lam
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Shit F Chew
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
| |
Collapse
|
2
|
Wang Q, Yu Z, Wei D, Chen W, Xie J. Mixotrophic Chlorella pyrenoidosa as cell factory for ultrahigh-efficient removal of ammonium from catalyzer wastewater with valuable algal biomass coproduction through short-time acclimation. BIORESOURCE TECHNOLOGY 2021; 333:125151. [PMID: 33892430 DOI: 10.1016/j.biortech.2021.125151] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 04/04/2021] [Accepted: 04/05/2021] [Indexed: 06/12/2023]
Abstract
To achieve ultrahigh-efficient ammonium removal and valuable biomass coproduction, Chlorella-mediated short-time acclimation was implemented in photo-fermentation. The results demonstrated short-time acclimation of mixotrophic Chlorella pyrenoidosa could significantly improve NH4+ removal and biomass production in shake flasks. After acclimation through two batch cultures in 5-L photo-fermenter, the maximum NH4+ removal rate (1,400 mg L-1 d-1) were achieved under high NH4+ level (4,750 mg L-1) in batch 3. In 50-L photo-fermenter, through one batch acclimated culture, the maximum NH4+ removal rate (2,212 mg L-1 d-1) and biomass concentration (58.4 g L-1) were achieved in batch 2, with the highest productivities of protein (5.56 g L-1 d-1) and total lipids (5.66 g L-1 d-1). The hypothetical pathway of nutrients assimilation in mixotrophic cells as cell factory was proposed with detailed discussion. This study provided a novel strategy for high-ammonium wastewater treatment without dilution, facilitating the algae-based "waste-to-treasure" bioconversion process for green manufacturing.
Collapse
Affiliation(s)
- Qingke Wang
- School of Food Science and Engineering, South China University of Technology, Guangzhou 510640, China
| | - Zongyi Yu
- School of Food Science and Engineering, South China University of Technology, Guangzhou 510640, China
| | - Dong Wei
- School of Food Science and Engineering, South China University of Technology, Guangzhou 510640, China; Research Institute for Food Nutrition and Human Health, Guangzhou, China.
| | - Weining Chen
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459, Singapore
| | - Jun Xie
- Key Laboratory of Tropical and Subtropical Fishery Resource Application and Cultivation, Chinese Academy of Fishery Sciences Pearl River Fisheries Research Institute, Guangzhou, China
| |
Collapse
|
3
|
Boo MV, Chew SF, Ip YK. Basolateral Na +/Ca 2+ exchanger 1 and Na +/K +-ATPase, which display light-enhanced gene and protein expression levels, could be involved in the absorption of exogenous Ca 2+ through the ctenidium of the giant clam, Tridacna squamosa. Comp Biochem Physiol A Mol Integr Physiol 2021; 259:110997. [PMID: 34051370 DOI: 10.1016/j.cbpa.2021.110997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 05/22/2021] [Accepted: 05/24/2021] [Indexed: 10/21/2022]
Abstract
Giant clams perform light-enhanced shell formation (calcification) and therefore need to increase the uptake of exogenous Ca2+ during illumination. The ctenidium of the fluted giant clam, Tridacna squamosa, is involved in light-enhanced Ca2+ uptake. It expresses the pore-forming voltage-gated calcium channel (VGCC) subunit alpha 1 (CACNA1) in the apical membrane of the epithelial cells, and the protein expression level of CACNA1 is upregulated in the ctenidium during illumination. This study aimed to elucidate the mechanism involved in the transport of the absorbed Ca2+ across the basolateral membrane of the ctenidial epithelial cells into the hemolymph. We obtained a homolog of Na+/Ca2+exchanger 1 (NCX1-like) from the ctenidium of T. squamosa, which comprised 2418 bp, encoding a protein of 806 amino acids (88.9 kDa). NCX1-like had a basolateral localization in the epithelial cells of the ctenidial filaments and tertiary water channels. Illumination resulted in significant increases in the transcript and protein levels of NCX1-like/NCX1-like in the ctenidium. Hence, NCX1-like could operate in conjunction with VGCC to increase the transport of Ca2+ from the ambient seawater into the hemolymph during illumination. Illumination also resulted in the upregulation of the gene and protein expression levels of Na+/K+-ATPase (NKA) α-subunit (NKAα/NKAα) in the ctenidium of T. squamosa. As light-enhanced extrusion of Ca2+ into the hemolymph through NCX1-like would lead to a greater influx of extracellular Na+, the increased expression of the basolateral NKA was required to augment the capacity of intracellular Na+ homeostasis.
Collapse
Affiliation(s)
- Mel V Boo
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Shit F Chew
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
| | - Yuen K Ip
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore.
| |
Collapse
|
4
|
Teh LSX, Poo JST, Boo MV, Chew SF, Ip YK. Using glutamine synthetase 1 to evaluate the symbionts' potential of ammonia assimilation and their responses to illumination in five organs of the giant clam, Tridacna squamosa. Comp Biochem Physiol A Mol Integr Physiol 2021; 255:110914. [PMID: 33540079 DOI: 10.1016/j.cbpa.2021.110914] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Revised: 01/23/2021] [Accepted: 01/25/2021] [Indexed: 11/16/2022]
Abstract
Nitrogen-deficient symbiotic dinoflagellates (zooxanthellae) living inside the fluted giant clam, Tridacna squamosa, need to obtain nitrogen from the host. Glutamine synthetase 1 (GS1) is a cytosolic enzyme that assimilates ammonia into glutamine. We determined the transcript levels of zooxanthellal GS1 (Zoox-GS1), which represented comprehensively GS1 transcripts of Symbiodinium, Cladocopium and Durusdinium, in five organs of T. squamosa. The outer mantle had significantly higher transcript level of Zoox-GS1 than the inner mantle, foot muscle, hepatopancreas and ctenidium, but the transcript ratios of Zoox-GS1 to zooxanthellal form II ribulose-1,5-bisphosphate carboxylase/oxygenase (Zoox-rbcII), which represented the potential of ammonia assimilation relative to the phototrophic potential, were comparable among these five organs. Based on transcript ratios of Zoox-GS1 to zooxanthellal Urease (Zoox-URE), the outer mantle had the highest potential of urea degradation relative to ammonia assimilation among the five organs, probably because urea degradation could furnish CO2 and NH3 for photosynthesis and amino acid synthesis, respectively, in the symbionts therein. The protein abundance of Zoox-GS1 was upregulated in the outer mantle and the inner mantle during illumination. Zoox-GS1 could catalyze light-enhanced glutamine formation using ammonia absorbed from the host or ammonia released through urea degradation in the cytoplasm. The glutamine produced could be used to synthesize other nitrogenous compounds, including amino acids in the cytoplasm or in the plastid of the dinoflagellates. Some of the amino acids synthesized by the symbionts in the inner mantle and foot muscle could be donated to the host to support shell organic matrix formation and muscle production, respectively.
Collapse
Affiliation(s)
- Leanne S X Teh
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Jeslyn S T Poo
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Mel V Boo
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Shit F Chew
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
| | - Yuen K Ip
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore.
| |
Collapse
|
5
|
Wang Q, Yu Z, Wei D. High-yield production of biomass, protein and pigments by mixotrophic Chlorella pyrenoidosa through the bioconversion of high ammonium in wastewater. BIORESOURCE TECHNOLOGY 2020; 313:123499. [PMID: 32554150 DOI: 10.1016/j.biortech.2020.123499] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 05/04/2020] [Accepted: 05/05/2020] [Indexed: 06/11/2023]
Abstract
To achieve a high consumption rate of ammonium with biomass coproduction, the mixotroph Chlorella pyrenoidosa was cultivated in high ammonium-high salinity wastewater medium in this study. The initial cell density, glucose and ammonium concentrations, and light intensity were optimized in shake flasks. A 5-L fermenter with surrounding LED (Light Emitting Diode) and a 50-L fermenter with inlet LED were employed for batch and semicontinuous cultivation. The results demonstrated that the highest contents of protein (56.7% DW) and total pigments (4.48% DW) with productivities of 5.62 g L-1 d-1 and 0.55 mg L-1 d-1, respectively, were obtained in 5-L photofermenter, while the maximum NH4+ consumption rate (1,800 mg L-1 d-1) and biomass yield (23.6 g L-1) were achieved in 50-L photofermenter. This study developed a novel strategy to convert high ammonium in wastewater to high-protein algal biomass, facilitating wastewater bioremediation and nitrogen recycling utilization by the mixotroph C. pyrenoidosa in photofermentation.
Collapse
Affiliation(s)
- Qingke Wang
- School of Food Science and Engineering, South China University of Technology, Guangzhou 510640, PR China
| | - Zongyi Yu
- School of Food Science and Engineering, South China University of Technology, Guangzhou 510640, PR China
| | - Dong Wei
- School of Food Science and Engineering, South China University of Technology, Guangzhou 510640, PR China.
| |
Collapse
|
6
|
Chew SF, Koh CZY, Hiong KC, Boo MV, Wong WP, Ip YK. The fluted giant clam (Tridacna squamosa) increases the protein abundance of the host's copper-zinc superoxide dismutase in the colorful outer mantle, but not the whitish inner mantle, during light exposure. Comp Biochem Physiol A Mol Integr Physiol 2020; 250:110791. [PMID: 32798693 DOI: 10.1016/j.cbpa.2020.110791] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 07/21/2020] [Accepted: 08/07/2020] [Indexed: 01/27/2023]
Abstract
The colorful outer mantle of giant clams contains abundance of symbiotic dinoflagellates (zooxanthellae) and iridocytes, and has direct exposure to light. In light, photosynthesizing dinoflagellates produce O2, and the host cells in the outer mantle would be confronted with hyperoxia-related oxidative stress. In comparison, the whitish inner mantle contains few symbiotic dinoflagellates and no iridocytes. It is involved in shell formation, and is shaded from light. CuZnSOD is a cytosolic enzyme that scavenges intracellular O2-. We had obtained from the outer mantle of the fluted giant clam, Tridacna squamosa, the complete cDNA coding sequence of a host-derived copper zinc superoxide dismutase (CuZnSOD), which comprised 462 bp and encoded for 154 amino acids with a calculated MW of 15.6 kDa. CuZnSOD was expressed strongly in the outer mantle, ctenidium, hepatopancreas and kidney. The transcript level of CuZnSOD remained unchanged in the outer mantle during light exposure, but the protein abundance of CuZnSOD increased ~3-fold after exposure to light for 6 or 12 h. By contrast, 12 h of light exposure had no significant effects on the gene and protein expression levels of CuZnSOD/CuZnSOD in the inner mantle. Hence, the increased expression of CuZnSOD in the outer mantle of T. squamosa was probably a host's response to ameliorate oxidative stress related to photosynthesis in the symbionts, and not simply due to increased metabolic rate in the host cells. Evidently, the host clam must possess light- or O2-responsive anti-oxidative defenses in order to align with the light-dependent photosynthetic activity of its symbionts.
Collapse
Affiliation(s)
- Shit F Chew
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore.
| | - Clarissa Z Y Koh
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Kum C Hiong
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Mel V Boo
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Wai P Wong
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Yuen K Ip
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| |
Collapse
|
7
|
Cao-Pham AH, Hiong KC, Boo MV, Choo CYL, Wong WP, Chew SF, Ip YK. Calcium absorption in the fluted giant clam, Tridacna squamosa, may involve a homolog of voltage-gated calcium channel subunit α1 (CACNA1) that has an apical localization and displays light-enhanced protein expression in the ctenidium. J Comp Physiol B 2019; 189:693-706. [DOI: 10.1007/s00360-019-01238-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 09/06/2019] [Accepted: 09/23/2019] [Indexed: 12/21/2022]
|
8
|
Chan CYL, Hiong KC, Choo CYL, Boo MV, Wong WP, Chew SF, Ip YK. Increased apical sodium-dependent glucose transporter abundance in the ctenidium of the giant clam Tridacna squamosa upon illumination. ACTA ACUST UNITED AC 2019; 222:jeb.195644. [PMID: 30877228 DOI: 10.1242/jeb.195644] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Accepted: 03/05/2019] [Indexed: 01/14/2023]
Abstract
Giant clams contain phototrophic zooxanthellae, and live in nutrient-deficient tropical waters where light is available. We obtained the complete cDNA coding sequence of a homolog of mammalian sodium/glucose cotransporter 1 (SGLT1) - SGLT1-like - from the ctenidium of the fluted giant clam, Tridacna squamosa SGLT1-like had a host origin and was expressed predominantly in the ctenidium. Molecular characterizations reveal that SGLT1-like of T. squamosa could transport urea, in addition to glucose, as other SGLT1s do. It has an apical localization in the epithelium of ctenidial filaments and water channels, and the apical anti-SGLT1-like immunofluorescence was stronger in individuals exposed to light than to darkness. Furthermore, the protein abundance of SGLT1-like increased significantly in the ctenidium of individuals exposed to light for 12 h, although the SGLT1-like transcript level remained unchanged. As expected, T. squamosa could perform light-enhanced glucose absorption, which was impeded by exogenous urea. These results denote the close relationships between light-enhanced glucose absorption and light-enhanced SGLT1-like expression in the ctenidium of T. squamosa Although glucose absorption could be trivial compared with the donation of photosynthates from zooxanthellae in symbiotic adults, SGLT1-like might be essential for the survival of aposymbiotic larvae, leading to its retention in the symbiotic stage. A priori, glucose uptake through SGLT1-like might be augmented by the surface microbiome through nutrient cycling, and the absorbed glucose could partially fulfill the metabolic needs of the ctenidial cells. Additionally, SGLT1-like could partake in urea absorption, as T. squamosa is known to conduct light-enhanced urea uptake to benefit the nitrogen-deficient zooxanthellae.
Collapse
Affiliation(s)
- Christabel Y L Chan
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Kum C Hiong
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Celine Y L Choo
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Mel V Boo
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Wai P Wong
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Shit F Chew
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
| | - Yuen K Ip
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore .,The Tropical Marine Science Institute, National University of Singapore, Kent Ridge, Singapore 119227, Republic of Singapore
| |
Collapse
|
9
|
Cao-Pham AH, Hiong KC, Boo MV, Choo CYL, Pang CZ, Wong WP, Neo ML, Chew SF, Ip YK. Molecular characterization, cellular localization, and light-enhanced expression of Beta-Na +/H + Exchanger-like in the whitish inner mantle of the giant clam, Tridacna squamosa, denote its role in light-enhanced shell formation. Gene 2019; 695:101-112. [PMID: 30763666 DOI: 10.1016/j.gene.2019.02.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2018] [Revised: 01/19/2019] [Accepted: 02/01/2019] [Indexed: 12/17/2022]
Abstract
The fluted giant clam, Tridacna squamosa, lives in symbiosis with photosynthetic zooxanthellae, and can engage in light-enhanced growth and shell formation. Light-enhanced shell formation necessitates the elimination of excess H+ from the extrapallial fluid adjacent to the shell. This study aimed to clone Na+/H+Exchanger (NHE) from the whitish inner mantle adjacent to the extrapallial fluid of T. squamosa, to determine its cellular and subcellular localization, and to evaluate the effect of light exposure on its mRNA expression level and protein abundance therein. The complete coding cDNA sequence of NHE obtained was identified as a homolog of beta NHE (βNHE-like). It consisted of 2925 bp, encoding for a polypeptide of 974 amino acids and 107.1 kDa, and was expressed predominantly in the inner mantle. There, βNHE-like was localized in the apical membrane of the seawater-facing epithelium by immunofluorescence microscopy. After exposure to light for 12 h, the seawater-facing epithelium of the inner mantle displayed consistently stronger immunostaining than that of the control exposed to 12 h of darkness. Western blotting confirmed that light exposure significantly enhanced the protein abundance of βNHE-like in the inner mantle. These results denote that some of the excess H+ generated during light-enhanced shell formation can be excreted through the light-dependent βNHE-like of the seawater-facing epithelium to minimize the impact on the whole-body pH. Importantly, the excreted H+ could dehydrate exogenous HCO3-, and facilitate the absorption of inorganic carbon through the seawater-facing epithelium dedicated for light-enhanced shell formation due to its close proximity with the shell-facing epithelium. NUCLEOTIDE SYMBOL COMBINATIONS: Pairs: R = A/G; W = A/T; Y = C/T. Triples: D = A/G/T.
Collapse
Affiliation(s)
- Anh H Cao-Pham
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Kum C Hiong
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Mel V Boo
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Celine Y L Choo
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Caryn Z Pang
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
| | - Wai P Wong
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Mei L Neo
- St. John's Island National Marine Laboratory, National University of Singapore, 18 Kent Ridge Road, Singapore 119227, Republic of Singapore
| | - Shit F Chew
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
| | - Yuen K Ip
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore; The Tropical Marine Science Institute, National University of Singapore, Kent Ridge, Singapore 119227, Republic of Singapore.
| |
Collapse
|
10
|
Ip YK, Hiong KC, Lim LJ, Choo CY, Boo MV, Wong WP, Neo ML, Chew SF. Molecular characterization, light-dependent expression, and cellular localization of a host vacuolar-type H + -ATPase (VHA) subunit A in the giant clam, Tridacna squamosa , indicate the involvement of the host VHA in the uptake of inorganic carbon and its supply to the symbiotic zooxanthellae. Gene 2018; 659:137-148. [DOI: 10.1016/j.gene.2018.03.054] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Revised: 03/13/2018] [Accepted: 03/16/2018] [Indexed: 10/17/2022]
|
11
|
Fam RR, Hiong KC, Choo CY, Wong WP, Chew SF, Ip YK. Molecular characterization of a novel algal glutamine synthetase (GS) and an algal glutamate synthase (GOGAT) from the colorful outer mantle of the giant clam, Tridacna squamosa , and the putative GS-GOGAT cycle in its symbiotic zooxanthellae. Gene 2018; 656:40-52. [DOI: 10.1016/j.gene.2018.02.062] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 02/09/2018] [Accepted: 02/23/2018] [Indexed: 12/25/2022]
|
12
|
Boo MV, Hiong KC, Goh EJK, Choo CYL, Wong WP, Chew SF, Ip YK. The ctenidium of the giant clam, Tridacna squamosa, expresses an ammonium transporter 1 that displays light-suppressed gene and protein expression and may be involved in ammonia excretion. J Comp Physiol B 2018; 188:765-777. [DOI: 10.1007/s00360-018-1161-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2017] [Revised: 04/03/2018] [Accepted: 04/15/2018] [Indexed: 01/31/2023]
|
13
|
Chan CYL, Hiong KC, Boo MV, Choo CYL, Wong WP, Chew SF, Ip YK. Light exposure enhances urea absorption in the fluted giant clam, Tridacna squamosa, and up-regulates the protein abundance of a light-dependent urea active transporter, DUR3-like, in its ctenidium. J Exp Biol 2018; 221:jeb176313. [PMID: 29540461 DOI: 10.1242/jeb.176313] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 03/12/2018] [Indexed: 12/26/2022]
Abstract
Giant clams live in nutrient-poor reef waters of the Indo-Pacific and rely on symbiotic dinoflagellates (Symbiodinium spp., also known as zooxanthellae) for nutrients. As the symbionts are nitrogen deficient, the host clam has to absorb exogenous nitrogen and supply it to them. This study aimed to demonstrate light-enhanced urea absorption in the fluted giant clam, Tridacna squamosa, and to clone and characterize the urea active transporter DUR3-like from its ctenidium (gill). The results indicate that T. squamosa absorbs exogenous urea, and the rate of urea uptake in the light was significantly higher than that in darkness. The DUR3-like coding sequence obtained from its ctenidium comprised 2346 bp, encoding a protein of 782 amino acids and 87.0 kDa. DUR3-like was expressed strongly in the ctenidium, outer mantle and kidney. Twelve hours of exposure to light had no significant effect on the transcript level of ctenidial DUR3-like However, between 3 and 12 h of light exposure, DUR3-like protein abundance increased progressively in the ctenidium, and became significantly greater than that in the control at 12 h. DUR3-like had an apical localization in the epithelia of the ctenidial filaments and tertiary water channels. Taken together, these results indicate that DUR3-like might participate in light-enhanced urea absorption in the ctenidium of T. squamosa When made available to the symbiotic zooxanthellae that are known to possess urease, the absorbed urea can be metabolized to NH3 and CO2 to support amino acid synthesis and photosynthesis, respectively, during insolation.
Collapse
Affiliation(s)
- Christabel Y L Chan
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Kum C Hiong
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Mel V Boo
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Celine Y L Choo
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Wai P Wong
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Shit F Chew
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
| | - Yuen K Ip
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
- The Tropical Marine Science Institute, National University of Singapore, Kent Ridge, Singapore 119227, Republic of Singapore
| |
Collapse
|
14
|
Koh CZY, Hiong KC, Choo CYL, Boo MV, Wong WP, Chew SF, Neo ML, Ip YK. Molecular Characterization of a Dual Domain Carbonic Anhydrase From the Ctenidium of the Giant Clam, Tridacna squamosa, and Its Expression Levels After Light Exposure, Cellular Localization, and Possible Role in the Uptake of Exogenous Inorganic Carbon. Front Physiol 2018; 9:281. [PMID: 29632495 PMCID: PMC5879104 DOI: 10.3389/fphys.2018.00281] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Accepted: 03/09/2018] [Indexed: 12/19/2022] Open
Abstract
A Dual-Domain Carbonic Anhydrase (DDCA) had been sequenced and characterized from the ctenidia (gills) of the giant clam, Tridacna squamosa, which lives in symbiosis with zooxanthellae. DDCA was expressed predominantly in the ctenidium. The complete cDNA coding sequence of DDCA from T. squamosa comprised 1,803 bp, encoding a protein of 601 amino acids and 66.7 kDa. The deduced DDCA sequence contained two distinct α-CA domains, each with a specific catalytic site. It had a high sequence similarity with tgCA from Tridacna gigas. In T. squamosa, the DDCA was localized apically in certain epithelial cells near the base of the ctenidial filament and the epithelial cells surrounding the tertiary water channels. Due to the presence of two transmembrane regions in the DDCA, one of the Zn2+-containing active sites could be located externally and the other one inside the cell. These results denote that the ctenidial DDCA was positioned to dehydrate [Formula: see text] to CO2 in seawater, and to hydrate the CO2 that had permeated the apical membrane back to [Formula: see text] in the cytoplasm. During insolation, the host clam needs to increase the uptake of inorganic carbon from the ambient seawater to benefit the symbiotic zooxanthellae; only then, can the symbionts conduct photosynthesis and share the photosynthates with the host. Indeed, the transcript and protein levels of DDCA/DDCA in the ctenidium of T. squamosa increased significantly after 6 and 12 h of exposure to light, respectively, denoting that DDCA could participate in the light-enhanced uptake and assimilation of exogenous inorganic carbon.
Collapse
Affiliation(s)
- Clarissa Z. Y. Koh
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Kum C. Hiong
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Celine Y. L. Choo
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Mel V. Boo
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Wai P. Wong
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Shit F. Chew
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, Singapore, Singapore
| | - Mei L. Neo
- St. John's Island National Marine Laboratory, National University of Singapore, Singapore, Singapore
| | - Yuen K. Ip
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
- The Tropical Marine Science Institute, National University of Singapore, Singapore, Singapore
| |
Collapse
|
15
|
Hiong KC, Cao-Pham AH, Choo CYL, Boo MV, Wong WP, Chew SF, Ip YK. Light-dependent expression of a Na +/H + exchanger 3-like transporter in the ctenidium of the giant clam, Tridacna squamosa, can be related to increased H + excretion during light-enhanced calcification. Physiol Rep 2018; 5:5/8/e13209. [PMID: 28438983 PMCID: PMC5408280 DOI: 10.14814/phy2.13209] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2017] [Accepted: 02/22/2017] [Indexed: 12/03/2022] Open
Abstract
Na+/H+ exchangers (NHEs) regulate intracellular pH and ionic balance by mediating H+ efflux in exchange for Na+ uptake in a 1:1 stoichiometry. This study aimed to obtain from the ctenidium of the giant clam Tridacna squamosa (TS) the complete cDNA sequence of a NHE3‐like transporter (TSNHE3), and to determine the effect of light exposure on its mRNA expression level and protein abundance therein. The coding sequence of TSNHE3 comprised 2886 bp, encoding 961 amino acids with an estimated molecular mass of 105.7 kDa. Immunofluorescence microscopy revealed that TSNHE3 was localized to the apical membrane of epithelial cells of the ctenidial filaments and the tertiary water channels. Particularly, the apical immunofluorescence of the ctenidial filaments was consistently stronger in the ctenidium of clams exposed to 12 h of light than those of the control kept in darkness. Indeed, light induced significant increases in the transcript level and protein abundance of TSNHE3/TSNHE3 in the ctenidium, indicating that the transcription and translation of TSNHE3/TSNHE3 were light‐dependent. As light‐enhanced calcification generates H+, the increased expression of TSNHE3/TSNHE3 in the ctenidium could be a response to augment H+ excretion in pursuance of whole‐body acid‐base balance during light exposure. These results signify that shell formation in giant clams requires the collaboration between the ctenidium, which is a respiratory and iono‐regulatory organ, and the inner mantle, which is directly involved in the calcification process, and provide new insights into the mechanisms of light‐enhanced calcification in giant clams.
Collapse
Affiliation(s)
- Kum C Hiong
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore
| | - Anh H Cao-Pham
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore
| | - Celine Y L Choo
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore
| | - Mel V Boo
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore
| | - Wai P Wong
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore
| | - Shit F Chew
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, Nanyang Walk, Singapore
| | - Yuen K Ip
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore .,The Tropical Marine Science Institute, National University of Singapore, Kent Ridge, Singapore
| |
Collapse
|
16
|
Ip YK, Koh CZY, Hiong KC, Choo CYL, Boo MV, Wong WP, Neo ML, Chew SF. Carbonic anhydrase 2-like in the giant clam, Tridacna squamosa: characterization, localization, response to light, and possible role in the transport of inorganic carbon from the host to its symbionts. Physiol Rep 2017; 5:e13494. [PMID: 29199178 PMCID: PMC5727267 DOI: 10.14814/phy2.13494] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 10/13/2017] [Indexed: 11/24/2022] Open
Abstract
The fluted giant clam, Tridacna squamosa, lives in symbiosis with zooxanthellae which reside extracellularly inside a tubular system. Zooxanthellae fix inorganic carbon (Ci) during insolation and donate photosynthate to the host. Carbonic anhydrases catalyze the interconversion of CO2 and HCO3-, of which carbonic anhydrase 2 (CA2) is the most ubiquitous and involved in many biological processes. This study aimed to clone a CA2 homolog (CA2-like) from the fleshy and colorful outer mantle as well as the thin and whitish inner mantle of T. squamosa, to determine its cellular and subcellular localization, and to examine the effects of light exposure on its gene and protein expression levels. The cDNA coding sequence of CA2-like from T. squamosa comprised 789 bp, encoding 263 amino acids with an estimated molecular mass of 29.6 kDa. A phenogramic analysis of the deduced CA2-like sequence denoted an animal origin. CA2-like was not detectable in the shell-facing epithelium of the inner mantle adjacent to the extrapallial fluid. Hence, CA2-like is unlikely to participate directly in light-enhanced calcification. By contrast, the outer mantle, which contains the highest density of tertiary tubules and zooxanthellae, displayed high level of CA2-like expression, and CA2-like was localized to the tubule epithelial cells. More importantly, exposure to light induced significant increases in the protein abundance of CA2-like in the outer mantle. Hence, CA2-like could probably take part in the increased supply of inorganic carbon (Ci) from the host clam to the symbiotic zooxanthellae when the latter conduct photosynthesis to fix Ci during light exposure.
Collapse
Affiliation(s)
- Yuen K. Ip
- Department of Biological SciencesNational University of SingaporeSingapore
- The Tropical Marine Science InstituteNational University of SingaporeSingapore
| | - Clarissa Z. Y. Koh
- Department of Biological SciencesNational University of SingaporeSingapore
| | - Kum C. Hiong
- Department of Biological SciencesNational University of SingaporeSingapore
| | - Celine Y. L. Choo
- Department of Biological SciencesNational University of SingaporeSingapore
| | - Mel V. Boo
- Department of Biological SciencesNational University of SingaporeSingapore
| | - Wai P. Wong
- Department of Biological SciencesNational University of SingaporeSingapore
| | - Mei L. Neo
- St. John's Island National Marine LaboratoryNational University of SingaporeSingapore
| | - Shit F. Chew
- Natural Sciences and Science EducationNational Institute of EducationNanyang Technological UniversitySingapore
| |
Collapse
|
17
|
Boo MV, Hiong KC, Choo CYL, Cao-Pham AH, Wong WP, Chew SF, Ip YK. The inner mantle of the giant clam, Tridacna squamosa, expresses a basolateral Na+/K+-ATPase α-subunit, which displays light-dependent gene and protein expression along the shell-facing epithelium. PLoS One 2017; 12:e0186865. [PMID: 29049367 PMCID: PMC5648256 DOI: 10.1371/journal.pone.0186865] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 10/09/2017] [Indexed: 12/11/2022] Open
Abstract
Na+/K+-ATPase (NKA) is essential for maintaining the Na+ and K+ gradients, and supporting the secondary active transport of certain ions/molecules, across the plasma membrane of animal cells. This study aimed to clone the NKA α-subunit (NKAα) from the inner mantle adjacent to the extrapallial fluid of Tridacna squamosa, to determine its subcellular localization, and to examine the effects of light exposure on its transcript level and protein abundance. The cDNA coding sequence of NKAα from T. squamosa comprised 3105 bp, encoding 1034 amino acids with an estimated molecular mass of 114 kDa. NKAα had a basolateral localization along the shell-facing epithelium of the inner mantle. Exposure to 12 h of light led to a significantly stronger basolateral NKAα-immunofluorescence at the shell-facing epithelium, indicating that NKA might play a role in light-enhanced calcification in T. squamosa. After 3 h of light exposure, the transcript level of NKAα decreased transiently in the inner mantle, but returned to the control level thereafter. In comparison, the protein abundance of NKAα remained unchanged at hour 3, but became significantly higher than the control after 12 h of light exposure. Hence, the expression of NKAα in the inner mantle of T. squamosa was light-dependent. It is probable that a higher expression level of NKA was needed in the shell-facing epithelial cells of the inner mantle to cope with a rise in Na+ influx, possibly caused by increases in activities of some Na+-dependent ion transporters/channels involved in light-enhanced calcification.
Collapse
Affiliation(s)
- Mel V. Boo
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore, Republic of Singapore
| | - Kum C. Hiong
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore, Republic of Singapore
| | - Celine Y. L. Choo
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore, Republic of Singapore
| | - Anh H. Cao-Pham
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore, Republic of Singapore
| | - Wai P. Wong
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore, Republic of Singapore
| | - Shit F. Chew
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, Singapore, Republic of Singapore
| | - Yuen K. Ip
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore, Republic of Singapore
- The Tropical Marine Science Institute, National University of Singapore, Kent Ridge, Singapore, Republic of Singapore
- * E-mail:
| |
Collapse
|
18
|
Ip YK, Hiong KC, Goh EJK, Boo MV, Choo CYL, Ching B, Wong WP, Chew SF. The Whitish Inner Mantle of the Giant Clam, Tridacna squamosa, Expresses an Apical Plasma Membrane Ca 2+-ATPase (PMCA) Which Displays Light-Dependent Gene and Protein Expressions. Front Physiol 2017; 8:781. [PMID: 29066980 PMCID: PMC5641333 DOI: 10.3389/fphys.2017.00781] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 09/25/2017] [Indexed: 12/16/2022] Open
Abstract
Giant clams live in symbiosis with extracellular zooxanthellae and display high rates of growth and shell formation (calcification) in light. Light-enhanced calcification requires an increase in the supply of Ca2+ to, and simultaneously an augmented removal of H+ from, the extrapallial fluid where shell formation occurs. We have obtained the complete coding cDNA sequence of Plasma Membrane Ca2+-ATPase (PMCA) from the thin and whitish inner mantle, which is in touch with the extrapallial fluid, of the giant clam Tridacna squamosa. The deduced PMCA sequence consisted of an apical targeting element. Immunofluorescence microscopy confirmed that PMCA had an apical localization in the shell-facing epithelium of the inner mantle, whereby it can actively secrete Ca2+ in exchange for H+. More importantly, the apical PMCA-immunofluorescence of the shell-facing epithelium of the inner mantle increased significantly after 12 h of exposure to light. The transcript and protein levels of PMCA/PMCA also increased significantly in the inner mantle after 6 or 12 h of light exposure. These results offer insights into a light-dependable mechanism of shell formation in T. squamosa and a novel explanation of light-enhanced calcification in general. As the inner mantle normally lacks light sensitive pigments, our results support a previous proposition that symbiotic zooxanthellae, particularly those in the colorful and extensible outer mantle, may act as light-sensing elements for the host clam.
Collapse
Affiliation(s)
- Yuen K Ip
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore.,The Tropical Marine Science Institute, National University of Singapore, Singapore, Singapore
| | - Kum C Hiong
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Enan J K Goh
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Mel V Boo
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Celine Y L Choo
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Biyun Ching
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Wai P Wong
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Shit F Chew
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, Singapore, Singapore
| |
Collapse
|
19
|
Gutner-Hoch E, Schneider K, Stolarski J, Domart-Coulon I, Yam R, Meibom A, Shemesh A, Levy O. Evidence for Rhythmicity Pacemaker in the Calcification Process of Scleractinian Coral. Sci Rep 2016; 6:20191. [PMID: 26847144 PMCID: PMC4742845 DOI: 10.1038/srep20191] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Accepted: 12/17/2015] [Indexed: 11/09/2022] Open
Abstract
Reef-building scleractinian (stony) corals are among the most efficient bio-mineralizing organisms in nature. The calcification rate of scleractinian corals oscillates under ambient light conditions, with a cyclic, diurnal pattern. A fundamental question is whether this cyclic pattern is controlled by exogenous signals or by an endogenous 'biological-clock' mechanism, or both. To address this problem, we have studied calcification patterns of the Red Sea scleractinian coral Acropora eurystoma with frequent measurements of total alkalinity (AT) under different light conditions. Additionally, skeletal extension and ultra-structure of newly deposited calcium carbonate were elucidated with (86)Sr isotope labeling analysis, combined with NanoSIMS ion microprobe and scanning electron microscope imaging. Our results show that the calcification process persists with its cyclic pattern under constant light conditions while dissolution takes place within one day of constant dark conditions, indicating that an intrinsic, light-entrained mechanism may be involved in controlling the calcification process in photosymbiotic corals.
Collapse
Affiliation(s)
- Eldad Gutner-Hoch
- The Mina &Everard Goodman Faculty of Life Sciences, Bar-Ilan University, 52900 Ramat-Gan, Israel
| | - Kenneth Schneider
- The Mina &Everard Goodman Faculty of Life Sciences, Bar-Ilan University, 52900 Ramat-Gan, Israel
| | - Jaroslaw Stolarski
- Institute of Paleobiology, Polish Academy of Sciences, Twarda 51/55, PL-00-818 Warsaw, Poland
| | - Isabelle Domart-Coulon
- MCAM UMR7245, Sorbonne Universités, Muséum National d'Histoire Naturelle, (CP54) 57 rue Cuvier, 75005 Paris, France
| | - Ruth Yam
- Department of Earth and Planetary Sciences, Weizmann Institute of Science, P.O.Box 26, 76100 Rehovot, Israel
| | - Anders Meibom
- Laboratory for Biological Geochemistry, School of Architecture, Civil and Environmental Engineering (ENAC), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.,Center for Advanced Surface Analysis, Institute of Earth Sciences, University of Lausanne, Lausanne, Switzerland
| | - Aldo Shemesh
- Department of Earth and Planetary Sciences, Weizmann Institute of Science, P.O.Box 26, 76100 Rehovot, Israel
| | - Oren Levy
- The Mina &Everard Goodman Faculty of Life Sciences, Bar-Ilan University, 52900 Ramat-Gan, Israel
| |
Collapse
|