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Astrobiology and habitability studies in preparation for future Mars missions: trends from investigating minerals, organics and biota

  • P. Ehrenfreund (a1) (a2), W.F.M. Röling (a3), C.S. Thiel (a4), R. Quinn (a5), M.A. Sephton (a6), C. Stoker (a5), J.M. Kotler (a1), S.O.L. Direito (a3), Z. Martins (a6), G.E. Orzechowska (a7), R.D. Kidd (a7), C.A van Sluis (a8) and B.H. Foing (a9)...

Abstract

Several robotic exploration missions will travel to Mars during this decade to investigate habitability and the possible presence of life. Field research at Mars analogue sites such as desert environments can provide important constraints for instrument calibration, landing site strategies and expected life detection targets. We have characterized the mineralogy, organic chemistry and microbiology of ten selected sample sites from the Utah desert in close vicinity to the Mars Desert Research Station (MDRS) during the EuroGeoMars 2009 campaign (organized by International Lunar Exploration Working Group (ILEWG), NASA Ames and ESA ESTEC). Compared with extremely arid deserts (such as the Atacama), organic and biological materials can be identified in a larger number of samples and subsequently be used to perform correlation studies. Among the important findings of this field research campaign are the diversity in the mineralogical composition of soil samples even when collected in close proximity, the low abundances of detectable polycyclic aromatic hydrocarbons (PAHs) and amino acids and the presence of biota of all three domains of life with significant heterogeneity. An extraordinary variety of putative extremophiles, mainly Bacteria and also Archaea and Eukarya was observed. The dominant factor in measurable bacterial abundance seems to be soil porosity and lower small (clay-sized) particle content. However, correlations between many measured parameters are difficult to establish. Field research conducted during the EuroGeoMars 2009 campaign shows that the geological history and depositional environment of the region, as well as the mineralogy influence the ability to detect compounds such as amino acids and DNA. Clays are known to strongly absorb and bind organic molecules often preventing extraction by even sophisticated laboratory methods. Our results indicate the need for further development and optimization of extraction procedures that release biological compounds from host matrices to enable the effective detection of biomarkers during future sampling campaigns on Earth and Mars.

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Alexander, C., Fogel, M., Yabuta, H. & Cody, G.D. (2007). The origin and evolution of chondrites recorded in the elemental and isotopic compositions of their macromolecular organic matter. Geochim. Cosmochim. Acta 71, 43804403.
Ansdell, M., Ehrenfreund, P. & McKay, C. (2011). Stepping stones toward global space exploration. Acta Astronaut. 68, 20982113.
Arvidson, R.E., Ruff, S.W., Morris, R.V., Ming, D.W., Crumpler, L.S., Yen, A.S., Squyres, S.W., Sullivan, R.J., Bell, J.F., Cabrol, N.A. et al. (2008). Spirit Mars rover mission to the Columbia Hills, Gusev Crater: mission overview and selected results from the Cumberland Ridge to Home Plate. J. Geophys. Res. 113, E12S33.
Aubrey, A., Cleaves, J., Chalmers, J., Skelley, A., Mathies, R., Grunthaner, F., Ehrenfreund, P. & Bada, J. (2006). Sulfate mineral and organic compounds on Mars. Geology 34, 357360.
Aubrey, A.D., Chalmers, J.H., Bada, J.L., Grunthaner, F.J., Amashukeli, X., Willis, P., Skelley, A.M., Mathies, R.A., Quinn, R.C., Zent, A. et al. (2008). The Urey instrument: an advanced in situ organic and oxidant detector for Mars exploration. Astrobiol., Spec. In Situ Instrum. Edn, 8, 583597.
Bada, J.L. & McDonald, G. (1995). Amino acid racemization on Mars; implications for the preservation of biomolecules from an extinct Martian biota. Icarus 114, 139143.
Bada, J.L., Wang, X.S. & Hamilton, H. (1999). Preservation of key biomolecules in the fossil record: Current knowledge and future challenges. Philos. Trans. R. Soc. Lond., Ser. B. Biol. Sci. 354, 7787.
Benner, A., Devine, K., Mateeva, L. & Powell, D. (2000). The missing organic molecules on Mars. Proc. Nat. Acad. Sci. U.S.A. 97(6):24252430.
Berner, R.A. (1971). Principles of Chemical Sedimentation. 240 pp. McGraw-Hill, New York.
Biemann, K. (1979). The implications and limitations of the findings of the Viking organic analysis experiment. J. Mol. Evol. 14, 6570.
Bishop, J.L., Saper, L., Beyer, R.A., Lowe, D., Wray, J.J., McKeown, N.K. & Parente, M. (2011). Possible sedimentary features in phyllosilicate-bearing rocks at Mawrth Vallis, Mars. In 42nd Lunar and Planetary Science Conference, Woodlands, Abstract No. 2374.
Bonnacorsi, R. & McKay, C.P. (2008). Total biomass and organics along a N-S moisture gradient of the Atacama region, Chile. In Lunar and Planetary Science Conference, Abstract. 1489.
Borst, A., Peters, S., Foing, B.H., Stoker, C., Wendt, L., Gross, C., Zavaleta, J., Sarrazin, P., Blake, D., Ehrenfreund, P. et al. (2010). Geochemical Results from EuroGeoMars MDRS Utah 2009 Campaign. LPI.41, 2744.
Boyd, E.S., Cummings, D.E. & Geesey, G.G. (2007). Mineralogy influences structure and diversity of bacterial communities associated with geological substrata in a pristine aquifer. Microbial. Ecol. 54, 170182.
Boynton, W.V., Ming, D.W., Kounaves, S.P., Young, S.M., Arvidson, R.E., Hecht, M.H., Hoffman, J., Niles, P.B., Hamara, D.K., Quinn, R. et al. (2009). Evidence for calcium carbonate at the Mars Phoenix landing site. Science 325(5936), 6164.
Brock, T.D., Smith, D.W. & Madigan, M.T. (1984). Biology of Microorganisms, 4th edn, pp. 1493. Prentice-Hall International Inc., Englewood Cliffs, NJ, USA.
Cairns-Smith, A.G. & Hartman, H. (eds) (1986). Clay Minerals and the Origin of Life, 193 pp. Cambridge University Press, Cambridge.
Carson, J.K., Campbell, L., Rooney, D., Clipson, N. & Gleeson, D.B. (2009). Minerals in soil select distinct bacterial communities in their microhabitats. FEMS Microbiol. Ecol. 67, 381388.
Carson, J.K., Gonzalez-Quiñones, V., Murphy, D., Hinz, D., Shaw, J.A. & Gleeson, D.B. (2010). Low pore connectivity increases bacterial diversity in soil. Appl. Environ. Microbiol. 76(12), 39363942.
Carter, J., Poulet, F., Ody, A., Bibring, J.-P. & Murchie, S. (2011). Global distribution, composition and setting of hydrous minerals on mars: a reappraisal. In 42nd Lunar and Planetary Science Conference, Woodlands, Abstract no. 2593.
Chan, M.A., Beitler, B., Parry, W.T., Ormö, J. & Komatsu, G. (2004). A possible terrestrial analogue for haematite concretions on Mars. Nature 429, 731734.
Chevrier, V. & Mathé, P.E. (2007). Mineralogy and evolution of the surface of Mars: a review. Planet. Space Sci. 55, 289314.
Chyba, C. & Sagan, C. (1992). Endogenous production, exogenous delivery and impact-shock synthesis of organic molecules: an inventory for the origins of life. Nature 355, 125132.
Clarke, J. & Stoker, C. (2011). Concretions in exhumed channels near Hanksville Utah: implications for Mars. Int. J. Astrobiol., in press.
Connon, S.A., Lester, E.D., Shafaat, H.S., Obenhuber, D.C. & Ponce, A. (2007). Bacterial diversity in hyperarid Atacama Desert soils. J. Geophys. Res. 112, G04S17.
Court, R.W., Baki, A., Sims, M., Cullen, D. & Sephton, M.A. (2010). Novel solvent systems for in situ extraterrestrial sample analysis. Planet. Space Sci. 58, 14701474.
Crecchio, C. & Stotzky, G. (1998). Binding of DNA on humic acids: effect on transformation of B. subtilis and resistance to DNase. Soil Biol. Biochem. 30, 10611067.
Dartnell, L.R., Desorgher, L., Ward, J.M. & Coates, A.J. (2007). Martian sub-surface ionising radiation: biosignatures and geology. Biogeosci. Discuss. 4(1), 455492.
Dartnell, L.R., Storrie-Lombardi, M. & Ward, J.M. (2010). Int. J. Astrobiol. 9(4), 245257.
Derenne, S., Robert, F., Skrzypczak-Bonduelle, A., Gourier, A., Binet, L. & Rouzaud, J.N. (2008). Molecular evidence for life in the 3.5 billion year old Warrawoona Chert. Earth Planet. Sci. Lett. 272, 476480.
Direito, S.O.L., Ehrenfreund, P., Marees, A., Staats, M., Foing, B. & Röling, W.F.M., (2011). A wide variety of putative extremophiles and large beta-diversity at the Mars Desert Research Station (Utah). Int. J. Astrobiol., in press.
Ehrenfreund, P., Rasmussen, S., Cleaves, J. & Chen, L. (2006). Experimentally tracing the key steps in the origin of life. Astrobiology 6(3), 490520.
Ertem, G. & Ferris, J.P. (1998). Formation of RNA oligomers on montmorillonite: site of catalysis. Orig. Life Evol. Biosph. 28, 485499.
Flynn, G.J. (1996). The delivery of organic matter from asteroids and comets to the early surface of Mars. Earth Moon Planets 72, 469474.
Foing, B.H., Stoker, C., Zavaleta, J., Ehrenfreund, P., Thiel, C., Sarrazin, P., Blake, D., Page, J., Pletser, V., Hendrikse, J. et al. (2011). Field astrobiology research in Moon–Mars analogue environment: instruments and methods. Int. J. Astrobiol., in press.
Formisano, V., Atreya, S., Encrenaz, T., Ignatiev, N. & Giuranna, M. (2004). Detection of methane in the atmosphere of Mars. Science 306, 17581761.
Glavin, D.P., Schubert, M., Botta, O., Kminek, G. & Bada, J.L. (2001). Detecting pyrolysis products from bacteria on Mars. Earth Planet. Sci. Lett. 185, 15.
Gómez-Silva, B., Rainey, F.A., Warren-Rhodes, K.A., McKay, C.P. & Navarro-González, R. (2008). Atacama Desert soil microbiology. In Microbiology of Extreme Soils, ed. Dion, P., Nautiyal, C.S. & Varma, A., volume 13, pp. 117132. Springer, Berlin, Heidelberg.
Grant, J., Westall, F., Beaty, D., Cady, S., Carr, M., Ciarletti, V., Coradini, A., Elfving, A., Glavin, D., Goesmann, F. et al. (2010). Two rovers to the same site on Mars, 2018: possibilities for cooperative science. Astrobiology 10, 663685.
Hammer, Ø., Harper, D.A.T. & Ryan, P.D. (2001). PAST: Paleontological statistics software package for education and data analysis. Palaeontol. Electron. 4(1), 9. http://palaeo-electronica.org/2001_1/past/issue1_01.htm
He, Z., Wu, L., Li, X., Fields, M.W. & Zhou, J. (2005). Empirical establishment of oligonucleotide probe design criteria. Appl. Environ. Microbiol. 71, 37533760.
Hecht, M.H., Kounaves, S.P., Quinn, R.C., West, S.J., Young, S., Ming, S.W., Catling, D.C., Clark, B.C., Boynton, W.V., Hoffman, J. et al. (2009). Detection of perchlorate and the soluble chemistry of the Martian soil at the Phoenix lander site. Science 325, 6467.
Henneberger, R.M., Walter, M.R. & Anitori, R.P. (2006). Extraction of DNA from acidic, hydrothermally modified volcanic soils. Environ. Chem. 3, 100104.
Herrera, A. & Cockell, C.S. (2007). Exploring microbial diversity in volcanic environments: a review of methods in DNA extraction. J. Microbiol. Methods 70, 112.
Hintze, L.H. & Kowallis, B.J. (2009). The Geologic History of Utah. Brigham Young University Geology Studies Special Publication 9, Provo, Utah.
Khanna, M. & Stotzky, G. (1992). Transformation of bacillus subtilis by DNA bound on montmorillonite and effect of DNAse on the transforming ability of bound DNA. Appl. Environ. Microbiol. 58, 19301939.
Klingelhofer, K., Morris, R.V., Bernhardt, B., Schröder, C., Rodionov, D.S., de Souza, P.A., Yen, A., Gellert, R., Evlanov, E.N., Zubkov, B. et al. (2004). Jarosite and hematite at Merdiani lanum from opportunity's Mossbauer spectrometer. Science 306, 1740.
Knoll, A.H. & Grotzinger, J. (2006). Water on Mars and the prospect of Martian life. Elements 2, 171175.
Kotler, J.M., Hinman, N.W., Richardson, C.D., Conly, A.G. & Scott, J.R. (2009). Laboratory simulations of prebiotic molecule stability in the jarosite mineral group; end member evaluation of detection and decomposition behavior related to Mars sample return. Planet. Space Sci. 57(12), 13811388.
Kotler, J.M., Hinman, N.W., Scott, J.R., Yan, B. & Stoner, D.L. (2008). Glycine identification in natural jarosites using laser-desorption Fourier transform mass spectrometry: implications for the search for life on Mars. Astrobiology 8(2), 253266.
Kotler, M., Quinn, R., Foing, B.H., Martins, Z. & Ehrenfreund, P. (2011). Analysis of mineral matrices of planetary soils analogs from the Utah desert. Int. J. Astrobiol., in press.
Liang, M.C., Hartman, H., Kopp, R., Kirschvink, J. & Yung, Y. (2006). Production of hydrogen peroxide in the atmosphere of a snowball earth and the origin of oxygenic photosynthesis. Proc. Nat. Acad. Sci. U.S.A. 103(50): 1889618899.
Lester, E.D., Satomi, M. & Ponce, A. (2007). Microflora of extreme arid Atacama Desert soils. Soil Biol. Biochem. 39, 704708.
Malin, M.C. & Edgett, K.S. (2003). Evidence for persistent flow and aqueous sedimentation on early Mars. Science 302, 19311934.
Marlow, J., Martins, Z. & Sephton, M. (2010). Organic host analogues and the search for life on Mars. Int. J. Astrobiol. 10, 3144.
Martins, Z., Hofmann, B., Gnos, R., Greenwood, R., Verchovsky, A., Franchi, I., Jull, A., Botta, O., Glavin, D., Dworkin, J. et al. (2007). Amino acid composition, petrology, geochemistry, 14C terrestrial age and oxygen isotopes of the Shisr 033 CR chondrite. Meteorit. Planet. Sci. 42, 15811595.
Martins, Z., Sephton, M.A., Foing, B.H. & Ehrenfreund, P. (2011). Extraction of amino acids from soils close to the Mars desert research station (MDRS), Utah. Int. J. Astrobiol., in press.
Milliken, R.E., Bristow, T. & Bish, D.L. (2011). Diagenesis of clay minerals on Mars and implications for the Mars Science Laboratory Rover. In 42nd Lunar and Planetary Science Conference, Woodlands, Abstract no. 2230.
Ming, D.W., Lauer, H.V., Archer, P.D., Sutter, B., Golden, D.C., Morris, R.V., Niles, P.B. & Boynton, W.V. (2009). Combustion of organic molecules by the thermal decomposition of perchlorate salts: Implications for organics at the Mars Phoenix Scout Landing Site. In 40th Lunar and Planetary Science Conference, Woodlands, Abstract no. 2241.
Moore, D.M. & Reynolds, R.C. (1997). X-Ray Diffraction and the Identification and Analysis of Clay Minerals. 378 pp. Oxford University Press, NewYork.
Mumma, M.J., Villanueva, G.L., Novak, R.E., Hewagama, T., Bonev, B.P., DiSanti, M.A., Mandell, A.M. & Smith, M.D. et al. (2009). Strong release of methane on Mars in northern summer 2003. Science 323, 10411045.
Murchie, S.L., Mustard, J.F., Ehlmann, B.L., Milliken, R.E., Bishop, J.L., McKeown, N.K., Noe Dobrea, E.Z., Seelos, F.P., Buczkowski, D.L., Wiseman, S.M. et al. (2009). A synthesis of Martian aqueous mineralogy after 1 Mars year of observations from the Mars Reconnaissance Orbiter. J. Geophys. Res. 114, E00D06.
Nadeau, P.H. & Reynolds, C.R. (1981). Burial and contact metamorphism in the Mancos Shale. Clays Clay Miner. 29, 249259.
Navarro-González, R., Rainey, F.A., Molina, P., Bagaley, D.R., Hollen, B.J., de la Rosa, J., Small, A.M., Quinn, R.C., Grunthaner, F.J., Cáceres, L. et al. (2003). Mars-like soils in the Atacama Desert, Chile, and the dry limit of microbial life. Science 302, 10181021.
Navarro-González, R., Vargas, E., de la Rosa, J., Raga, A.C. & McKay, C.P. (2010). Reanalysis of the Viking results suggests perchlorate and organics at midlatitudes on Mars. J. Geophys. Res. 115(12), E12010.
Ormö, J., Komatsu, G., Chan, M.A., Beitler, B. & Parry, W.T. (2004). Geological features indicative of processes related to the hematite formation in Meridiani Planum and Aram Chaos, Mars: a comparison with diagenetic hematite deposits in southern Utah, USA. Icarus 171, 295316.
Orzechowska, G.E., Kidd, R., Foing, B.H., Kanik, I., Stoker, C. & Ehrenfreund, P. (2011). Analysis of Mars analog soil samples using solid phase microextraction, organic solvent extraction and gas chromatography/mass spectrometry. Int. J. Astrobiol., in press.
Parnell, J., Cullen, D., Sims, M.R., Bowden, S., Cockell, C.S., Court, R., Ehrenfreund, P., Gaubert, F., Grant, W., Parro, V. et al. (2007). Searching for life on Mars: selection of molecular targets for ESA's Aurora Exomars Mission. Astrobiology 7/4, 578604.
Patel, M.R., Zarnecki, J.C. & Catling, D.C. (2002). Ultraviolet radiation on the surface of Mars and the Beagle 2 UV sensor. Planet. Space Sci. 50(9), 915927.
Peeters, Z., Quinn, R., Martins, Z., Sephton, M.A., Becker, L., Brucato, J., Grunthaner, F. & Ehrenfreund, P. (2009). Habitability on planetary surfaces: interdisciplinary preparation phase for future Mars missions. Int. J. Astrobiol. 8(4), 301315.
Pietramellara, G., Ascher, J., Ceccherini, M., Nannipieri, P. & Wenderoth, D. (2007). Adsorption of pure and dirty bacterial DNA on clay minerals and their transformation frequency. Biol. Fertil. Soils 43(6), 731739.
Ponnamperuma, C., Shimoyama, A. & Friebele, E. (1982). Clay and the origin of life. Orig. Life 12(1), 940.
Poulet, F., Beaty, D.W., Bibring, J.-P., Bish, D., Bishop, J.L., Noe Dobrea, E., Mustard, J.F., Petit, S. & Roach, L.H. (2009). Key scientific Questions and key investigations from the First International Conference on Martian Phyllosilicates. Astrobiology 9, 257267.
Quinn, R., Zent, A., Grunthaner, F., Ehrenfreund, R., Taylor, C. & Garry, J. (2005). Detection and characterization of oxidizing acids in the Atacama Desert using the Mars oxidation instrument. Planet. Space Sci. 53, 13761388.
Richardson, C.D., Hinman, N.W., McJunkin, T.R., Kotler, J.M. & Scott, J.R. (2008). Exploring biosignatures associated with Thenardite by geomatrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry (GALDI-FTICR-MS). Geomicrobiol. J. 25, 19.
Rutherford, P.M. & Juma, N.G. (1992). Influence of texture on habitable pore space and bacterial-protozoan populations in soil. Biol. Fertil. Soils 12, 221227.
Saeki, K. & Sakai, M. (2009). The influence of soil organic matter on DNA adsorptions on andosols. Microbes Environ. 24(2), 175179.
Sephton, M.A. (2002). Organic compounds in carbonaceous meteorites. Nat. Prod. Rep. 19, 292311.
Sephton, M.A. (2010). Organic geochemistry and the exploration of Mars, J. Cosmol. 5, 11411149.
Soffen, G.A. (1977). The Viking project. J. Geophys. Res. 82(28), 39593970.
Squyres, S., Grotzinger, J.P., Arvidson, R.E., Bell, J.F., Calvin, W., Christensen, P.R., Clark, B.C., Crisp, J.A., Farrand, W.H., Herkenhoff, K.E. et al. (2004). In-situ evidence for an ancient aquaeus environment at Meridaini Planum. Science 306, 1709.
Squyres, S.W., Knoll, A.H., Arvidson, R.E., Ashley, J.W., Bell III, J.F., Calvin, W.M., Christensen, P.R., Clark, B.C., Cohen, B.A., de Souza, P.A. Jr. et al. (2009). Exploration of Victoria crater by the Mars rover opportunity. Science 324, 10581061.
Stoker, C., Zent, A., Catling, D.C., Douglas, S., Marshall, J.R., Archer, D., Clark, B., Kounaves, S.P., Lemmon, M.T., Quinn, R. et al. (2010). Habitability of the Phoenix landing site. J. Geophys. Res. 115, E00E20.
Stoker, C., Clarke, J., Direito, S., Martin, K., Zavaleta, J., Blake, D. & Foing, B.H. (2011). Chemical, mineralogical, organic and microbial properties of subsurface soil cores from the Mars Desert Research Station Utah, a phyllosilicate and sulfate rich Mars analog site. Int. J. Astrobiol., in press.
Tegelaar, E.W., Deleeuw, J.W., Derenne, S. & Largeau, C. (1989). A reappraisal of kerogen formation, Geochem. Geophys. Acta 53, 31033106.
Ten Kate, I. (2010). Organics on Mars. Astrobiology 10(6), 589.
Tielens, A.G.G.M. (2008). Interstellar polycyclic aromatic hydrocarbon molecules. Annu. Rev. Astron. Astrophys. 46, 289337.
Thiel, C., Ehrenfreund, P., Foing, B.F., Pletser, V. & Ullrich, O. (2011a). PCR-based analysis of microbial communities during the EuroGeoMars campaign at Mars Desert Research Station, Utah. Int. J. Astrobiol., in press.
Thiel, C., Pletser, V. & Foing, B.F. (2011b). Human crew related aspects for Astrobiology research. Int. J. Astrobiol., in press.
Tosca, N.J. & Hurowitz, J.A. (2011). Neoformation, diagenesis and the clay cycle on early Mars. In 42nd Lunar and Planetary Science Conference, Woodlands, Abstract no. 2031.
Tosca, N.J., Knoll, A.H. & Mc Lennan, S.M. (2008). Water activity and the challenge for life on early Mars. Science 320, 12041207.
Tritz, J.P., Herrmann, D., Bisseret, P., Connan, J. & Rohmer, M. (1999). Abiotic and biological hopanoids transformation: towards the formation of molecular fossils of the hopane series. Org. Geochem. 30, 499514.
Westall, F. (2009). Life on an anaerobic planet. Science 232, 471472.
Westall, F., Brack, A., Hofmann, B., Horneck, G., Kurat, G., Maxwell, J., Ori, G.G., Pillinger, C., Raulin, F., Thomas, N. et al. (2000). An ESA study for the search for life on Mars. Planet. Space Sci. 48, 181202.
Yan, B., Stoner, D.L., Kotler, J.M., Hinman, N.W. & Scott, J.R. (2007). Detection of biosignatures by geomatrix-assisted laser desorption/ionization (GALDI) mass spectrometry. Geomicrobiol. J. 24(3–4), 379385.
Yen, A.S., Kim, S.S., Hecht, M.H., Frant, M.S. & Murray, B. (2000). Evidence that the reactivity of the Martian soil is due to superoxide ions. Science 289, 19091912.
Zegers, T. et al. (2011). Summary outcome and recommendations: workshop on landing sites for exploration missions, Leiden/Noordwijk, January 2011 (http://www.planetarygis.org/wiki/Workshop2011/Results).
Zahnle, K., Freedman, R.S. & Catling, D.C. (2011). Is there methane on Mars? Icarus 212, 493503.
Zhou, J., Bruns, M.N. & Tiedje, J.M. (1996). DNA recovery from soils of diverse composition. Appl. Environ. Microbiol. 62(2), 316322.

Keywords

Astrobiology and habitability studies in preparation for future Mars missions: trends from investigating minerals, organics and biota

  • P. Ehrenfreund (a1) (a2), W.F.M. Röling (a3), C.S. Thiel (a4), R. Quinn (a5), M.A. Sephton (a6), C. Stoker (a5), J.M. Kotler (a1), S.O.L. Direito (a3), Z. Martins (a6), G.E. Orzechowska (a7), R.D. Kidd (a7), C.A van Sluis (a8) and B.H. Foing (a9)...

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