OPCE-STR.vp In memoriam U:\ACTA BOTANICA\Acta-Botan 1-10\Magnus.vp 9. travanj 2010 13:35:36 Color profile: Disabled Composite 150 lpi at 45 degrees U:\ACTA BOTANICA\Acta-Botan 1-10\Magnus.vp 9. travanj 2010 13:35:36 Color profile: Disabled Composite 150 lpi at 45 degrees Acta Bot. Croat. 69 (1), 125–133, 2010 CODEN: ABCRA 25 ISSN 0365–0588 In memoriam Dr. Volker Magnus Dr. Volker Magnus, an outstanding Croatian plant physiologist and member of the edi- torial board of this journal, passed away on July 30, 2009. Volker was born March 22, 1942 in Eckernförde, Germany. He came to Zagreb as Deutscher Akademischer Austauschdienst (DAAD) fellow to study experimental biology at the Faculty of Natural Sciences and Mathematics, University of Zagreb, where he ob- tained a B.S. degree in 1967. Volker decided to continue his education in Zagreb, and as a graduate student began to carry out research in the Tracer Laboratory, Department of Or- ganic Chemistry and Biochemistry at Ru|er Bo{kovi} Institute, under the supervision of Drs. Dina Keglevi}, Sonja Iskri} and Sergije Kveder, scientists interested in indole metabo- lism in biological systems. Volker’s fascination with plants led him to choose indole metabo- lism in plants as his research topic. His MSc thesis, completed in 1971, dealt with the isola- tion of indole-3-methanol from pea seedlings, a metabolite of indole -3-acetic acid (IAA) (MAGNUS et al. 1971). His thesis marked the beginning of his life-long interest in plant hor- mone auxins. In his doctoral study, Volker isolated and synthesized a variety of tryptophol glycosides (MAGNUS et al. 1973, MAGNUS 1979), and obtained a Ph.D. in the field of plant biochemistry in 1976. As one of his mentors and a long time colleague, I want to stress the many outstand- ing qualities of Volker Magnus: he was a very intelligent and gifted man, with a broad knowledge about plants and had a very good dexterity in organic synthesis. He was modest and self-effacing. Early in his career he became an independent sci- entist, proving himself in planning and running experiments and in writing papers. With time he became adept in helping colleagues around him with advice and in correction of their papers, making use of his excellent mastery of English, German and even Croatian. He left us much too soon. Sonja Iskri} ACTA BOT. CROAT. 69 (1), 2010 125 U:\ACTA BOTANICA\Acta-Botan 1-10\Magnus.vp 9. travanj 2010 13:35:37 Color profile: Disabled Composite 150 lpi at 45 degrees Volker moved for postdoctoral training to Prof. Robert S. Bandurski’s laboratory, Michigan State University, (Michigan, USA) in 1977. He worked on the development of a gas chromatography-mass spectrometry based isotope dilution assay for the plant hormone IAA. Combining his expertise in plant indoles with extensive knowledge of synthetic or- ganic chemistry, he produced two stable deuterated forms of IAA (Fig. 1), thus enriching the auxin field with its first quantitative GC-MS isotope-dilution based assay (MAGNUS et al. 1980). His work provided the foundation stone for the development of quantitative mea- surements of auxin in plants. Upon completing his work on the first heavy isotope labeled IAA, he returned to the Ru|er Bo{kovi} Institute where he remained for the duration of his career. Beginning in 1979, Volker and his first Ph.D. student, Goran La}an, continued doing research on Volker’s »first love«: tryptophol and its glycosides. They synthesized a number of conju- gate standards and identified endogenous glycosides in 120 different samples ranging from bacteria and fungi, to algae and plants (LA]AN et al. 1984, LA]AN et al. 1985). For that sci- entific achievement they obtained, in 1986, the »Award for Outstanding Research in Plant Physiology«, from the Gli{i} Foundation, University of Belgrade. In addition to auxin con- jugates, Volker worked on alkyl and halogen auxins derivatives with his Ph.D. students, Neboj{a Ili} and Eduard Dolu{i}, who later continued their careers abroad. I met Volker in the late 1960s at the Ru|er Bo{kovi} Institute’s Laboratory of Stereochemistry and Natural Products, where he worked part-time as a technician, and I was an organic chemistry novice in my junior year at the University of Zagreb. At a time when thousands of its citizens were emigrating to Germany in search of work, a soft-spoken German Gastarbeiter in Yugoslavia was an oddity. All of us who knew him then quickly recognized his keen sense of a language that was not native to him, as well as his meticulous approach to scientific endeavors. The will- ingness to learn from and selflessly share his knowledge with others was a lifelong trait. Volker was an excellent synthetic organic chemist for whom synthesis was not just a tool for probing plant physiology’s unanswered questions, but also a chal- lenge to which he responded with dedication and passion. As his first graduate stu- dent, I enjoyed his friendship and was given the chance to learn critical thinking and rigorous scrutiny crucial for scientific research. Volker’s professional and personal legacy will always remind me of my dear friend, »the best plant physiologist among chemists and the best organic chemist among plant physiologists.« Goran La}an 126 ACTA BOT. CROAT. 69 (1), 2010 ISKRI] S., JELASKA S., KOJI]-PRODI] B. et al. Fig. 1. Deuterated IAA with the labels on the ring (MAGNUS et al. 1980). U:\ACTA BOTANICA\Acta-Botan 1-10\Magnus.vp 9. travanj 2010 13:35:38 Color profile: Disabled Composite 150 lpi at 45 degrees Volker always maintained excellent contacts with colleagues abroad. He returned to Michigan State University in 1982, working for three years with Norman Good and Roger Hangarter on IAA-conjugates and their application in tissue cultures (MAGNUS et al. 1992a, b). In the period between 1991 and 1996 he took a scientific leave to work first in the Sandberg laboratory in Umea, Sweden, until 1993 (JAKAS et al. 1993, ILI] et al. 1997), and then moved to Mark Brenner’s laboratory at the University of Minnesota, Minneapolis, MN, to work on 4-Cl-IAA in pea with Jocelyn Ozga and Dennis Reinecke (REINECKE et al. 1995, MAGNUS et al. 1997). Upon returning to the Ru|er Bo{kovi} Institute, in 2003, Volker found- ed the Laboratory of Chemical Biology, at the Department of Molecular Biology. Volker was a scientist with interdisciplinary interests. As an excellent chemist and a passionate plant biologist, he collaborated with colleagues from divergent scientific fields. At his home institute, he collaborated for more than twenty years with Dr. Koji}-Prodi} and her group (Biljana Nigovi}, Sanja Tomi}, Snje`ana Antoli}-Steiner and Branimir Berto{a) on the structure/activity relationship of auxins (Fig. 2). More than 50 indolic compounds were characterized structurally (most notably through use of X-ray diffraction, NMR and IR spectroscopy), and classified as active auxins, antagonists, or inactive compounds, based on different bioassays and modeling approaches. The collaboration resulted in more than 30 scientific papers, among which there were some representative ones on IAA amino acid conjugates (DUDDECK at al. 1989; KOJI]-PRODI] et al. 1991a, 1993, 1999), n-alkyl-sub- stituted IAAs (ILI] et al.1991; KOJI]-PRODI] et al. 1991b; NIGOVI] et al. 1996, 2000; ANTOLI] et al. 2003), and halogen-substituted IAAs (ANTOLI] et al. 1996, 1999).These pa- pers represent in the open literature the most comprehensive study of the 3-dimensional characterization of auxin and auxin-like molecules. Volker was also deeply involved in dis- cussions on auxin binding protein (ABP1) and its role in the auxin signaling pathway (Fig. 3) (BERTO[A et al. 2008.). Volker was a silent and unobtrusive person, very analytical in thinking, and some- times indecisive and cautious in reaching conclusions. Through the years, we suc- cessfully worked on many international projects funded by the US National Science Foundation, United States Department of Agriculture, the European Community, and in bilateral collaborative projects, producing more than 30 scientific papers, ex- hibiting with mutual respect and tolerance. Collaboration with Volker was fruitful, exhilarating, sometimes followed by surprises, an inseparable part of his personality. Biserka Koji}-Prodi} ACTA BOT. CROAT. 69 (1), 2010 127 IN MEMORIAM DR. VOLKER MAGNUS Fig. 2. 3D structure of indole-3-acetic acid (IAA) (KOJI]-PRODI] et al. 1999). U:\ACTA BOTANICA\Acta-Botan 1-10\Magnus.vp 9. travanj 2010 13:35:39 Color profile: Disabled Composite 150 lpi at 45 degrees More recently, Volker’s interests became focused on advanced methods for auxin local- ization, in the production of a novel class of antibodies based on linking ring-aminoalkyl substituted IAA to proteins (DOLU[I] et al. 2001, ILI] et al. 2005, [O[KI] and MAGNUS 2007, TOMA[I] et al. 2007, [O[KI] and MAGNUS, 2009), and the use of carbon nanotube micro- electrodes to record the auxin flux (MANCUSO et al. 2005). As a plant biologist, and that was how he primarily identified himself, he was interested in plant physiology and hormonal regulation of plant growth and developmental processes. He collaborated with Prof. Sibila Jelaska, Biology Department, Faculty of Science, Uni- versity of Zagreb, in testing indole-3-ethanol and its sugar conjugates in the embryonic cul- tures of Cucurbita pepo (JELASKA et al. 1985). For more than twenty years they taught a joint course entitled: »Mechanisms of Plant Development«, at the doctoral study of biology at the Faculty of Science. Collaborating with his close friend and colleague from student days, Dr. Nikola Ljube{i}, and later with Dr. Mercedes Wrischer, Volker was involved in research into plastids in different plant species. In a fruitful collaboration with the Labora- tory of Electron Microscopy, he was involved in studies of the effect of growth substances on the greening process of non-green plastids (SALOPEK et al. 1998, 2000, 2002). Recently, he also took part in a collaborative study of ultrastructure and function of different types of plastids (WRISCHER et al. 1999, 2000, 2001, 2007, 2009). Working with his Ph.D student Branka Salopek-Sondi during the last decade, he be- came actively involved in research on the role of plant hormones in the regulation of postanthesis development of the Christmas rose (Helleborus niger L.) flower. In this un- 128 ACTA BOT. CROAT. 69 (1), 2010 ISKRI] S., JELASKA S., KOJI]-PRODI] B. et al. Fig. 3. Hypothesis on the mechanism of the auxin binding protein, ABP1, and its role in the auxin signaling pathway (BERTO[A et al. 2008). U:\ACTA BOTANICA\Acta-Botan 1-10\Magnus.vp 9. travanj 2010 13:35:40 Color profile: Disabled Composite 150 lpi at 45 degrees usual plant, attractive flowers, white at anthesis, become intensively green upon fruit de- velopment, representing an excellent model for understanding cellular control of plastid development (Fig. 3) (SALOPEK-SONDI et al. 2000, 2002; SALOPEK-SONDI and MAGNUS 2007). In collaboration with colleagues from abroad, the hormones cytokinins, gibberel- lins, and auxins have been identified in this plant model and their role was discussed (TARKOWSKI et al. 2006, AYELE et al. 2009, PEN^IK et al. 2009). Volker was my mentor and teacher since 1993, when I started my scientific career at the Ru|er Bo{kovi} Institute. The enjoyable moments of our collaboration were field trips to the forests of Gorski kotar where we collected the flowers of the Christ- mas rose (Helleborus niger L.) for our research (Fig. 4). During our trips through the forest Volker was able to identify almost every plant along our way and had little stories about them, from either the biological or culinary aspects. Even more fasci- nating, he used to recognize birds hidden in the tree bushes based on their songs. Volker was a passionate naturalist, a very good botanist and a true plant lover. In the last few years, we shared an office and spent many afternoons in discussions over a cup of coffee. I will miss him. Branka Salopek-Sondi Auxin conjugates attracted Volker’s attention during his entire scientific career. In the last few years, in collaboration with Prof. Jutta Ludwig-Müller from the Technical Univer- sity of Dresden (Germany), he participated in research into the structure, function, and reg- ulation of auxin amidohydrolases, enzymes that hydrolyze amino acid conjugates of auxin, releasing free active forms (Fig. 5.) (CAMPANELLA et al. 2004, SAVI] et al. 2009). Volker was a member of the Croatian Society of Plant Biology (CSPB) for a long time, and its president from 1997 until 2001. He was the creator of the most recent Statutes of the Society and of the Society’s representative emblem: the flower of Aquilegia kitaibelii, an ACTA BOT. CROAT. 69 (1), 2010 129 IN MEMORIAM DR. VOLKER MAGNUS Fig. 4. The Christmas rose (Helleborus niger L.) flowers: white at anthesis (A), becoming green during fruit development (B). U:\ACTA BOTANICA\Acta-Botan 1-10\Magnus.vp 9. travanj 2010 13:35:42 Color profile: Disabled Composite 150 lpi at 45 degrees endemic Croatian plant residing in the mountains of Velebit and Plje{ivica (Fig. 5). It will always remind us of Volker, as well as Volker’s famous bean soup, the one he used to cook for his friends and colleagues (the recipe for Volker’s bean soup is posted on the CSPB web site: http://www.hdbb.hr). He was member of the editorial board of Acta Botanica Croatica from 1998 and was responsible for plant physiology and biochemistry. Volker was entirely dedicated to science until the very end of his life. Although retired since 2008, he was in the laboratory daily, continuing his research, writing, and discussing problems with young colleagues. Volker Magnus came to Croatia and joined our scientific community silently; he lived and worked among us for more than 40 years, mostly unno- 130 ACTA BOT. CROAT. 69 (1), 2010 ISKRI] S., JELASKA S., KOJI]-PRODI] B. et al. Fig. 5. Comparative model of auxin amidohydrolase from Brassica rapa L. with highlighted Mn2+ as a metal cofactor (violet spheres) (SAVI] et al. 2009). Fig. 6. The flower of the Croatian endemic plant (Aquilegia kitaibelii Schot) (left) inspired Volker to create the emblem of the Croatian Society of Plant Biology (right). Photo of Aquilegia flowers is provided by professor Toni Nikoli} from the Department of Botany, Division of Biology, Faculty of Science, University of Zagreb. U:\ACTA BOTANICA\Acta-Botan 1-10\Magnus.vp 9. travanj 2010 13:35:45 Color profile: Disabled Composite 150 lpi at 45 degrees ticed and silent, and left us, unexpectedly, in the same way. His work and scientific contri- butions to our and international science was anything but silent and unnoticed; it will re- main priceless. References ANTOLI], A., KOJI]-PRODI], B., TOMI], S., NIGOVI], B., MAGNUS, V., COHEN, J. D., 1996: Structural studies on monofluorinated derivatives of the phytohormone indole-3-acetic acid (auxin). Acta Crystallographica B 52, 651–661. ANTOLI], S., SALOPEK, B., KOJI]-PRODI], B., MAGNUS, V., COHEN, J. D., 1999: Structural characterization and auxin properties of dichlorinated indole-3-acetic acids. Plant Growth Regulation 27, 21–31. ANTOLI], S., DOLU[I], E., KO@I], E. K., KOJI]-PRODI], B., MAGNUS, V., RAMEK, M., TOMI], S., 2003: Auxin activity and molecular structure of 2-alkylindole-3-acetic acids. Plant Growth Regulation 39, 235–252. AYELE, B. T., MAGNUS, V., MIHALJEVI], S., PREBEG, T., ^O@-RAKOVAC, R., OZGA, J. A., REINECKE, D. M., MANDER, L. N., KAMIYA, Y., YAMAGUCHI, S., SALOPEK-SONDI, B., 2009: Endogenous gibberellin profile during Christmas rose (Helleborus niger L.) flower and fruit development. Journal of Plant Growth Regulation DOI: 10.1007/ s00344-009-9124-5. BERTO[A, B., KOJI]-PRODI], B., WADE, R. C., TOMI], S., 2008: Mechanism of auxin inter- action with auxin binding protein (ABP1): a molecular dynamics simulation study. Bio- physical Journal 94, 27–37. CAMPANELLA, J. J., OLAJIDE, A. F., MAGNUS, V., LUDWIG-MÜLLER, J., 2004: A novel auxin conjugate hydrolase from wheat with substrate specificity for longer side-chain auxin amide conjugates. Plant Physiology 135, 2230–2240. DOLU[I], E., KOWALCZYK, M., MAGNUS, V., SANDBERG, G., NORMANLY, J., 2001: Biotiny- lated indoles as probes for indole-binding proteins. Bioconjugate Chemistry 12, 152– 162. DUDDECK, H., HIEGEMANN, M., SIMEONOV, M. F., KOJI]-PRODI], B., NIGOVI], B., MAGNUS, V., 1989: Conformational study of some amino acid conjugates of indol-3-yl-acetic acid (IAA) by 1H-NOE-difference spectroscopy. Structure/auxin activity relationships. Zeit- schrift für Naturforschung C 44, 543–554. ILI], N., KLAI], B., MAGNUS, V., VIKI]-TOPI], D., GÁCS-BAITZ, E., 1991: Synthesis of 5-alkylindole-3-acetic acids for use as plant hormone analogues. Croatica Chemica Acta 64, 79–88. ILI], N., MAGNUS, V., OSTIN, A., SANDBERG, G., 1997: Stable-isotope labeled metabolites of the phytohormone, indole-3-acetic acid. Journal of Labelled Compounds and Radio- pharmaceuticals 39, 433–440. ILI], N., HABU[, I., BARKAWI, L. S., PARK, S., [EFANI], Z., KOJI]-PRODI], B., COHEN, J. D., MAGNUS, V., 2005: Aminoethyl-substituted indole-3-acetic acids for the preparation of tagged and carrier-linked auxin. Bioorganic and Medicinal Chemistry 13, 3229–3240. JAKAS, A., MAGNUS, V., HORVAT, [., SANDBERG, G., 1993: Synthesis of the -D-glucosyl es- ter of [carbonyl-13C]-indole-3-acetic acid. Journal of Labelled Compounds and Radio- pharmaceuticals 33, 933–939. ACTA BOT. CROAT. 69 (1), 2010 131 IN MEMORIAM DR. VOLKER MAGNUS U:\ACTA BOTANICA\Acta-Botan 1-10\Magnus.vp 9. travanj 2010 13:35:45 Color profile: Disabled Composite 150 lpi at 45 degrees JELASKA, S., MAGNUS, V., SERETIN, M., LA]AN, G., 1985: Induction of embryogenic callus in Cucurbita pepo hypocotyl explants by indole-3-ethanol and its sugar conjugates. Physiologia Plantarum 64, 237–242. KOJI]-PRODI], B., NIGOVI], B., HORVATI], D., RU@I]-TORO[, @., MAGNUS, V., DUAX, W. L., STEZOWSKI, J. J., BRESCIANI-PAHOR, N., 1991a: Comparison of the structures of the plant growth hormone, indole-3-acetic acid, and six of its amino acid conjugates. Acta Crystallographica B 47, 107–115. KOJI]-PRODI], B., NIGOVI], B., TOMI], S., ILI], N., MAGNUS, V., GIBA, Z., KONJEVI], R., DUAX, W. L., 1991b: Structural studies on 5-(n-alkyl)-substituted derivatives of the plant hormone, indole-3-acetic acid. Acta Crystallographica B 47, 1010–1019. KOJI]-PRODI], B., NIGOVI], B., PUNTAREC, V., TOMI], S., MAGNUS, V., 1993: Structural comparison of biologically active and inactive conjugates of a-amino acids and the plant growth hormone (auxin) indole-3-acetic acid. Acta Crystallographica B 49, 367–374. KOJI]-PRODI], B., MAGNUS, V., ANTOLI], S., TOMI], S., SALOPEK-SONDI, B., 1999: Struc- ture/activity correlations for auxins. Acta Botanica Croatica 58, 27–37. LA]AN, G., MAGNUS, V., JERI^EVI], B., KUNST, LJ., ISKRI], S., 1984: Formation of trypto- phol galactoside and an unknown tryptophol ester in Euglena gracilis. Plant Physiol- ogy 76, 889–893. LA]AN, G., MAGNUS, V., [IMAGA, [., ISKRI], S., HALL, P. J., 1985: Metabolism of tryptophol in higher and lower plants. Plant Physiology 78, 447–454. MAGNUS, V., ISKRI], S., KVEDER, S., 1971: Indole-3-methanol – a metabolite of indole-3- -acetic acid in pea seedlings. Planta 97, 116–125. MAGNUS, V., ISKRI], S., KVEDER, S., 1973: The formation of tryptophol glucoside in the tryptamine metabolism of pea seedlings. Planta 110, 57–62. MAGNUS, V., 1979: Tryptophyl b-D-glucopyranoside: chemical synthesis, metabolism, and growth promoting activity. Carbohydrate Research 76, 261–264. MAGNUS, V., BANDURSKI, R. S., SCHULZE, A., 1980: Synthesis of 4,5,6,7 and 2,4,5,6,7 deute- rium-labeled indole-3-acetic acid for use in mass spectrometric assays. Plant Physiol- ogy 66, 775–781. MAGNUS, V., HANGARTER, R. P., GOOD, N. E., 1992a: Interaction of free indole-3-acetic acid and its amino acid conjugates in tomato hypocotyl cultures. Journal of Plant Growth Regulation 11, 67–75. MAGNUS, V., NIGOVI],, B., HANGARTER, R. P., GOOD, N. E., 1992b: N -(indol-3-ylacetyl) amino acids as sources of auxin in plant tissue culture. Journal of Plant Growth Regula- tion 11, 19–28. MAGNUS, V., OZGA, J. A., REINECKE, D. M., PIERSON, G. L., LARUE, T. A., COHEN, J. D., BRENNER, M. L., 1997: 4-chloroindole-3-acetic and indole-3-acetic acids in Pisum sativum. Phytochemistry 46, 675–681. MANCUSO, S., MARRAS, A. M., MAGNUS, V., BALU[KA, F., 2005: Noninvasive and continu- ous recordings of auxin fluxes in intact root apex with a carbon nanotube-modified and self-referencing microelectrode. Analytical Biochemistry 341, 344–351. NIGOVI], B., KOJI]-PRODI], B., ANTOLI], S., TOMI], S., PUNTAREC, V., COHEN, J. D., 1996: Structural studies on monohalogenated derivatives of the phytohormone indole-3-ace- tic acid (auxin). Acta Crystallographica B 52, 332–343. 132 ACTA BOT. CROAT. 69 (1), 2010 ISKRI] S., JELASKA S., KOJI]-PRODI] B. et al. U:\ACTA BOTANICA\Acta-Botan 1-10\Magnus.vp 9. travanj 2010 13:35:45 Color profile: Disabled Composite 150 lpi at 45 degrees NIGOVI], B., ANTOLI], S., KOJI]-PRODI], B., KIRALJ, R., MAGNUS, V., SALOPEK-SONDI, B., 2000: Correlation of structural and physico-chemical parameters with the bioactivity of alkylated derivatives of indole-3-acetic acid, a phytohormone (auxin). Acta Crystallo- graphica B 56, 94–111. PEN^IK, A., ROL^IK, J., NOVAK, O., MAGNUS, V., BARTAK, P., BUCHTIK, R., SALOPEK-SONDI, B., STRNAD, M., 2009: Isolation of novel indole-3-acetic acid conjugates by immuno- affinity extraction. Talanta 80, 651–655. REINECKE, D. M., OZGA, J. A., MAGNUS, V., 1995: Effect of halogen substitution of indole-3-acetic acid on biological activity in pea fruit. Phytochemistry 40, 1361–1366. SALOPEK, B., WRISCHER, M., LJUBE[I], N., MAGNUS, V., 1998: Greening of non-trans- formed and Agrobacterium rhizogenes transformed adventitious potato roots. Biologia 53, 127–132. SALOPEK-SONDI, B., KOVA^, M., LJUBE[I], N., MAGNUS, V., 2000: Fruit initiation in Helleborus niger L. triggers chloroplast formation and photosynthesis in the perianth. Journal of Plant Physiology 157, 357–364. SALOPEK-SONDI, B., KOVA^, M., PREBEG, T., MAGNUS, V., 2002: Developing fruit direct post-floral morphogenesis in Helleborus niger L. Journal of Experimental Botany 53, 1949–1957. SALOPEK-SONDI, B., MAGNUS, V., 2007: Developmental studies in the Christmas rose (Helleborus niger L.). International Journal of Plant Developmental Biology 1, 151–159. SAVI], B., TOMI], S., MAGNUS, V., GRUDEN, K., BARLE, K., GRENKOVI], R., LUDWIG- -MÜLLER, J., SALOPEK-SONDI, B., 2009: Auxin amidohydrolases from Brassica rapa cleave the alanine conjugate of indolepropionic acid as a preferable substrate: a bio- chemical and modeling approach. Plant and Cell Physiology 50, 1577–1589. [O[KI], M., MAGNUS, V., 2007: Binding of ring-substituted indole-3-acetic acids to human serum albumin. Bioorganic and Medicinal Chemistry 15, 4595–4600. [O[KI], M., MAGNUS, V., 2009: Interaction of indole derivatives with immobilized 3, 5-dinitrobenzoyl-phenylglycine. QSAR & Combinatorial Science 28, 1276–1283. TARKOWSKI, P., TARKOWSKA, D., NOVAK, O., MIHALJEVI], S., MAGNUS, V., STRNAD, M., SALOPEK-SONDI, B., 2006: Cytokinins in the perianth, carpels and developing fruit of Helleborus niger L. Journal of Experimental Botany 10, 2237–2247. TOMA[I], A., BERTO[A, B., TOMI], S., [O[KI], M., MAGNUS, V., 2007: Binding behavior of amino acid conjugates of indole-3-acetic acid to immobilized human serum albumin. Journal of Chromatography A 1154, 240–249. WRISCHER, M., LJUBE[I], N., PREBEG, T., MAGNUS, V., 1999: The succession of chromo- plast structures in Impatiens noli-tangere flowers. Phyton 39, 49–59. WRISCHER, M., LJUBE[I], N., MAGNUS, V., DEVIDÉ, Z., 2000: Structural and functional characteristics of overwintering blackberry leaves. Acta Botanica Croatica 59, 5–16. WRISCHER, M., PREBEG, T., MAGNUS, V., LJUBE[I], N., 2001: Ultrastructural study of chromoplast components rich in glycolipids. Acta Botanica Croatica 60, 141–147. WRISCHER, M., PREBEG, T., MAGNUS, V., LJUBE[I], N., 2007: Crystals and fibrils in chromoplast plastoglobules of Solanum capsicastrum fruit. Acta Botanica Croatica 66, 81–87. ACTA BOT. CROAT. 69 (1), 2010 133 IN MEMORIAM DR. VOLKER MAGNUS U:\ACTA BOTANICA\Acta-Botan 1-10\Magnus.vp 9. travanj 2010 13:35:45 Color profile: Disabled Composite 150 lpi at 45 degrees WRISCHER, M., PREBEG, T., MAGNUS, V., LJUBE[I], N., 2009: Unusual thylakoid structures appearing during degradation of the photosynthetic apparatus in chloroplasts. Acta Botanica Croatica 68, 1–9. Sonja Iskri}, Sibila Jelaska, Biserka Koji}-Prodi}, Goran La}an, Nikola Ljube{i}, Mercedes Wrischer, Branka Salopek-Sondi Ru|er Bo{kovi} Institute, Zagreb Faculty of Science, University of Zagreb 134 ACTA BOT. CROAT. 69 (1), 2010 ISKRI] S., JELASKA S., KOJI]-PRODI] B. et al. U:\ACTA BOTANICA\Acta-Botan 1-10\Magnus.vp 13. travanj 2010 9:15:45 Color profile: Disabled Composite 150 lpi at 45 degrees