Publications

1. Welc-Stanowska R., Pietras R., Mielecki B., Sarewicz M., Luchowski R., Widomska J., Grudziński W., Osyczka A., Gruszecki W. I. (2023) How Do Xanthophylls Protect Lipid Membranes from Oxidative Damage? J. Phys. Chem. Lett. 14: 7440-7444
2. Kuleta P., Pietras R., Andrys-Olek J., Wójcik-Augustyn A., Osyczka A. (2023) Probing molecular interactions of semiquinone radicals at quinone reduction sites of cytochrome bc₁ by X-band HYSCORE EPR spectroscopy and quantum mechanical calculations, Phys. Chem. Chem Psych., 25: 21935
    
3. Borek A., Ekiert R., Osyczka A. (2023), On the inter-monomer electron transfer in cytochrome bc₁, BBA - Bioenergetics, 1864: 148981
    
4. Bujnowicz Ł., Pietras R., Sarewicz M., Osyczka A. (2023) Low-cost stopped-flow and freeze-quench device for double mixing, HardwareX, 14: e00409
    
5. Sarewicz M., Szwalec M., Pintscher S., Indyka P., Rawski M., Pietras R., Mielecki B., Koziej Ł., Jaciuk M., Glatt S., Osyczka A. (2023) High-resolution cryo-EM structures of plant cytochrome b₆f at work, Science Advances, 9: eadd9688
    
6. Szwalec M., Bujnowicz Ł., Sarewicz M., Osyczka A. (2022) Unexpected Heme Redox Potential Values Implicate an Uphill Step in Cytochrome b₆f, J. Phys. Chem. B, 47: 9771–9780
7. Kulig, K., Karnas, E., Woznicka, O., Kuleta, P., Zuba-Surma, E., Pyza, E., Osyczka, A., Kozik, A., Rapala-Kozik, M., Karkowska-Kuleta, J. (2022) Insight into the properties and immunoregulatory effect of extracellular vesicles produced by Candida glabrata, Candida parapsilosis, and Candida tropicalis biofilms. Front. in Cell. Inf. Microbiol., 12: 879237
8. Sarewicz, M., Osyczka, A. (2021) Cytochrome bc₁ complex (respiratory chain complex III). in: Encyclopedia of Biological Chemistry III (Jez, J. Ed.) Eslevier Inc., 2: 502-511.
9. Kuleta, P., Lasham, J., Sarewicz, M., Ekiert, I., Sharma, V., Ekiert, R., Osyczka, A. (2021) Hydrogen bonding rearrangement by a mitochondrial disease mutation in cytochrome bc₁ perturbs heme b_H redox potential and spin state. Proc. Natl. Acad. Sci. USA, 118: e2026169118.
10. Lorencik, K., Ekiert, R., Zhu, Y., McBride, M. J., Gennis, R. B, Sarewicz, M., Osyczka, A. (2021) The monoheme c subunit of respiratory alternative complex III is not essential for electron transfer to cytochrome aa₃ in Flavobacterium johnsoniae. Microbiol. Spectr., 9: e00135-21
11. Sarewicz, M., Pintscher, S., Bujnowicz, Ł., Wolska, M., Osyczka, A. (2021) The high-spin heme b_L mutant exposes dominant reaction leading to the formation of the semiquinone spin-coupled to the [2Fe-2S]⁺ cluster at the Q_o site of Rhodobacter capsulatus cytochrome bc₁. Front. Chem., 9: 658877
12. Sarewicz, M., Pintscher, S., Pietras, R., Borek, A., Bujnowicz, Ł., Hanke, G., Cramer, W. A., Finazzi, G., Osyczka, A. (2021) Catalytic reactions and energy conservation in the cytochrome bc₁ and b₆f complexes of energy-transducing membranes. Chemical Rev., 121: 2020-2108
13. Pagacz, J., Broniec, A., Wolska, M., Osyczka, A., Borek, A. (2021) ROS signaling capacity of cytochrome bc₁: Opposing effects of adaptive and pathogenic mitochondrial mutations. Free Rad. Biol. Med., 163: 243-254.
14. Karkowska-Kuleta, J., Kulig, K., Karnas, E., Zuba-Surma, E., Woznicka, O., Pyza, E., Kuleta, P., Osyczka, A., Rapala-Kozik, M., Kozik, A. (2020) Characteristics of extracellular vesicles released by the pathogenic yeast-like fungi Candida glabrata, Candida parapsilosis and Candida tropicalis. Cells, 9: 1722
15. Handzlik, G., Magott, M., Arczyński, M., Sheveleva, A. M., Tuna, F., Sarewicz, M., Osyczka, A., Rams, M., Vieru, V., Chibotaru, L. F., Pinkowicz, D. (2020) Magnetization dynamics and coherent spin manipulation of a propeller Gd(III) complex with the smallest helicene ligand. J. Phys. Chem. Lett., 11: 1508-1515
16. Bujnowicz, Ł., Sarewicz, M., Osyczka, A. (2020) Unusual semiquinone as an electron buffer in enzymatic quinone oxidation. Postępy Biochemii (Advances in Biochemistry), 66: 91-99 (in Polish)
17. Pintscher, S., Wójcik-Augustyn, A., Sarewicz, M., Osyczka, A., (2020) Charge polarization imposed by the binding site facilitates enzymatic redox reactions of quinone. Biochim. Biophys. Acta, 1861: 148216
18. Purhonen, J., Grigorjev, V., Ekiert, R., Aho, N., Rajendran, J., Pietras, R., Truve, K., Wistrom, M., Sharma, V., Osyczka, A., Fellman, V., Kallijarvi, J. (2020) A spontaneous mitonuclear epistasis converging on Rieske Fe-S protein exacerbates complex III deficiency in mice. Nat. Commun., 11: 322
19. Godlewska, U., Bilska, B., Zegar, A., Brzoza, P., Borek, A., Murzyn, K., Bochenska, O., Morytko, A., Kuleta, P., Kozik, A., Pyza, E., Osyczka, A., Zabel, B. A., Cichy, J. (2019)  The antimicrobial activity of chemerin-derived peptide p4 requires oxidative conditions.  J. Biol. Chem., 294: 1267-1278
20. Bujnowicz Ł., Borek A., Kuleta P., Osyczka A., (2019) Suppression of superoxide production by a spin-spin coupling between semiquinone and Rieske cluster. FEBS, 593: 3-12
21. Borek A, Ekiert R., Osyczka A, (2018) Functional flexibility of electron flow between quinol oxidation Q_o site of cytochrome bc₁ and cytochrome c revealed by combinatory effects of mutations in cytochrome b, iron-sulfur protein and cytochrome c₁ Bioch. Biophys. Acta 1859, 754-761
22. Pintscher S, Pietras R, Sarewicz M, Osyczka A, (2018) Electron sweep across four b-hemes of cytochrome bc1 revealed by unusual paramagnetic properties of the Qi semiquinone intermediate Bioch. Biophys. Acta 1859, 459-469
23. Sarewicz, M. Bujnowicz, Ł., Osyczka, A. (2018) Generation of semiquinone-[2Fe-2S]⁺ spin-coupled center at the Qo site of cytochrome bc₁ in redox-poised, illuminated photosynthetic chromatopchores from Rhodobacter capsulatus Bioch. Biophys. Acta 1859, 145-153
24. Borek A, Ekiert R, Osyczka A. (2018) Advances in understanding mechanism and physiology of cytochromes bc. Book chapter in: Mechanisms of primary energy transduction in biology. Chemical biology no. 5. Edited by M. Wikström. Royal Society of Chemistry London pp. 192-214.
25. Bhaduri, S., Stadnytskyi, V., Zakharov, S.D., Hasan, S.S., Bujnowicz, Ł., Sarewicz, M., Savikhin, S., Osyczka, A., Cramer, W.A., (2017) Pathways of transmembrane electron transfer in cytochrome bc complexes: dielectric heterogeneity and interheme coulombic interactions J. Phys. Chem. B 121, 975-983
26. Sarewicz, M., Bujnowicz, Ł., Bhaduri, S., Singh, S.K., Cramer, W.A., Osyczka, A. (2017) Metastable radical state, nonreactive with oxygen, is inherent to catalysis by respiratory and photosynthetic cytochromes bc1/b6f Proc. Nat. Acad. Sci. USA 114, 1323-1328
27. Postila, P.A., Kaszuba, K., Kuleta, P., Vattulainen, I., Sarewicz, M., Osyczka, A., Róg, T. (2016) Atomistic determinants of co-enzyme Q reduction at the Qi-site of the cytochrome bc1 complex Sci. Rep. 6, 33607
28. Kuleta, P., Sarewicz, M., Postila, P., Róg, T., Osyczka, A. (2016) Identifying involvement of Lys251/Asp252 pair in electron transfer and associated proton transfer at the quinone reduction site of Rhodobacter capsulatus cytochrome bc1 BBA Bioenergetics 1857, 10, 1661-1668
29. Piertras, R., Sarewicz, M., Osyczka, A. (2016) Distinct properties of semiquinone species detected at the ubiquinol oxidation Qo site of cytochrome bc1 and their mechanistic implications J. R. Soc. Interface 13 (118)
30. Sarewicz, M., Ekiert, R., Osyczka A. (2016) Book chapter: Inter-Monomer Electron Transfer in Cytochrome bc Complexes in: Cytochrome Complexes: Evolution, Structures, Energy Transduction, and Signaling Advances in Photosynthesis and Respiration vol. 41 (Springer)
31. Borek, A., Ekiert, R., Osyczka, A. (2016) Molekularne efekty mutacji mitochondrialnych w genie kodującym cytochrom b kompleksu III i ich wpływ na poziom produkcji wolnych rodników Postępy Biochemii 62 (2) 162-172
32. Ekiert, E., Borek, A., Kuleta, P., Czernek, J., Osyczka, A. (2016) Mitochondrial disease-related mutations at the cytochrome b-iron-sulfur protein (ISP) interface: Molecular effects on the large-scale motion of ISP and superoxide generation studied in Rhodobacter capsulatus cytochrome bc1. BBA Bioenergetics
33. Pintscher, S., Kuleta, P., Cieluch, E., Sarewicz, M., Osyczka, A. (2016) Tuning of hemes b equilibrium redox potential is not required for cross-membrane electron transfer. J Biol Chem 291, 6872-6881 
34. Sarewicz, M., Dutka, M., Pietras, R., Borek, A., Osyczka, A. (2015) Effect of H bond removal and changes in the position of the iron-sulphur head domain on the spin-lattice relaxation properties of the [2Fe-2S](2+) Rieske cluster in cytochrome bc(1). Phys Chem Chem Phys 17(38), 25297-25308
35. Borek, A., Kuleta, P., Ekiert, R., Pietras, R., Sarewicz, M., Osyczka, A. (2015) Mitochondrial Disease-related Mutation G167P in Cytochrome b of Rhodobacter capsulatus Cytochrome bc1 (S151P in Human) Affects the Equilibrium Distribution of [2Fe-2S] Cluster and Generation of Superoxide. J Biol Chem 290, 23781-23792 
36. Sarewicz, M., Osyczka, A. (2015) Electronic Connection Between the Quinone and Cytochrome c Redox Pools and Its Role in Regulation of Mitochondrial Electron Transport and Redox Signaling. Physiol Rev. 95:219-243
37. Pietras, R., Sarewicz, M., Osyczka, A. (2014) Molecular organization of cytochrome c2 near the binding domain of cytochrome bc1 studied by electron spin-lattice relaxation enhancement. J Phys Chem B 118: 6634–6643
38. Ekiert, R., Czapla, M., Sarewicz, M., Osyczka, A. (2014) Hybrid fusions show that inner-monomer electron transfer robustly supports cytochrome bc1 function in vivo. Biochem Biophys Res Commun 451: 270–275
39. Sarewicz, M., Dutka, M., Pintscher, S., Osyczka, A. (2013) Triplet State of the Semiquinone-Rieske Cluster as an Intermediate of Electronic Bifurcation Catalyzed by Cytochrome bc1. Biochemistry 52 (37), 6388–6395
40. Pöyry, S., Cramariuc, O., Postila, P.A., Kaszuba, K., Sarewicz, M., Osyczka, A., Vattulainen, I., Róg, T. (2013)Atomistic simulations indicate cardiolipin to have an integral role in the structure of the cytochrome bc1 complex. Biochim Biophys Acta 1827(6):769-78
41. Postila, P.A., Kaszuba, K., Sarewicz, M., Osyczka, A., Vattulainen, I., Róg, T. (2013)Key role of water in proton transfer at the Qo-site of the cytochrome bc1 complex predicted by atomistic molecular dynamics simulations. Biochim Biophys Acta 1827(6):761-8
42. Czapla, M., Cieluch, E., Borek, A., Sarewicz, M., Osyczka, A. (2013)Catalytically-relevant electron transfer between two hemes bL in the hybrid cytochrome bc1-like complex containing a fusion of Rhodobacter sphaeroides and capsulatus cytochromes b. Biochim Biophys Acta 1827(6):751-60
43. Kaszuba, K., Postila, P.A., Cramariuc, O., Sarewicz, M., Osyczka, A., Vattulainen, I., Róg, T. (2013) Parameterization of the prosthetic redox centers of the bacterial cytochrome bc 1 complex for atomistic molecular dynamics simulations Theor Chem Acc 132:1370
44. Czapla, M., Sarewicz, M., and Osyczka, A. (2012) Fusing proteins as an approach to study bioenergetic enzymes and processes. Biochim Biophys Acta. 1817(10), 1847-1851
45. Czapla. M., Borek, A., Sarewicz, M., and Osyczka, A. (2012) Enzymatic activities of isolated cytochrome bc1-like complexes containing fused cytochrome b subunits with asymmetrically inactivated segments of electron transfer chains. Biochemistry 51, 829-835.
46. Czapla. M., Borek, A., Sarewicz, M., and Osyczka, A. (2012) Fusing two cytochromes b of Rhodobacter capsulatus cytochrome bc1 using various linkers defines a set of protein templates for asymmetric mutagenesis. Protein Eng., Des. Sel. 25, 15-25.
47. Rutherford, A. W., Osyczka, A., and Rappaport, F. (2012) Back-reactions, short-circuits, leaks and other energy wasteful reactions in biological electron transfer: Redox tuning to survive life in O2. FEBS Lett. 586, 603-616
48. Sarewicz, M., Pietras, R., Froncisz, W., and Osyczka, A. (2011) Reorientation of cytochrome c2 upon interaction with oppositely charged macromolecules probed by SR EPR: implications for the role of dipole moment to facilitate collisions in proper configuration for electron transfer. Metallomics 3, 404-409.
49. Sarewicz, M., Borek, A., Cieluch, E., Świerczek, M., and Osyczka, A. (2010) Discrimination between two possible reaction sequences that create potential risk of generation of deleterious radicals by cytochrome bc1. Implications for the mechanism of superoxide production. Biochim. Biophys. Acta 1797, 1820-1827.
50. Świerczek, M., Cieluch, E., Sarewicz, M., Borek, A., Moser, C. C., Dutton, P. L., and Osyczka, A. (2010) An electronic bus bar lies in the core of cytochrome bc1. Science 329, 451-454.
51. Cieluch, E., Pietryga, K., Sarewicz, M., and Osyczka, A. (2010) Visualizing changes in electron distribution in coupled chains of cytochrome bc1 by modifying barrier for electron transfer between the FeS cluster and heme c1. Biochim. Biophys. Acta 1797, 296-303.
52. Sarewicz, M., Dutka, M., Froncisz, W., and Osyczka, A. (2009) Magnetic interactions sense changes in distance between heme bL and the iron-sulfur cluster in cytochrome bc1. Biochemistry 48, 5708-5720.
53. Borek, A., Sarewicz, M., and Osyczka, A. (2008) Movement of the iron-sulfur head domain of cytochrome bc1 transiently opens the catalytic Qo site for reaction with oxygen. Biochemistry 47, 12365-12370.
54. Sarewicz, M., Borek, A., Daldal, F., Froncisz, W., and Osyczka, A. (2008) Demonstration of short-lived complexes of cytochrome c with cytochrome bc1 by EPR spectroscopy. Implications for the mechanism of interprotein electron transfer. J. Biol. Chem. 283, 14826-24836.
55. Zhang, H., Chobot, S. E., Osyczka, A., Wraight, C. A., Dutton, P. L., and Moser, C. C. (2008) Quinone and non-quinone redox couples in complex III. J. Bioenerg. Biomembr. 40, 493-499.
56. Sarewicz, M., Szytuła, S., Dutka, M., Osyczka, A., and Froncisz, W. (2008) Estimation of binding parameters for the protein-protein interaction using a site-directed spin labeling and EPR spectroscopy. Eur. Biophys. J. 37, 483-493.
57. Lee, D-W., Ozturk, Y., Osyczka, A., Cooley, J. W., and Daldal, F. (2008) Cytochrome bc1-cy fusion complexes reveal the distance constraints for functional electron transfer between photosynthetic components. J. Biol. Chem. 283, 13973-13982.
58. Ozturk, Y., Lee, D-W., Mandaci, S., Osyczka, A., Prince, R. C., and Daldal, F. (2008) Soluble variants of Rhodobacter capsulatus membrane-anchored cytochrome cy are efficient photosynthetic electron carriers. J. Biol. Chem. 283, 13964-13972.
59. Zhang, H., Osyczka, A., Dutton, P. L., and Moser, C. C. (2007) Exposing the complex III Qo site semiquinone radical. Biochim. Biophys. Acta 1767, 883-887.
60. Zhang, H., Osyczka, A., Moser, C. C., and Dutton, P. L. (2006) Resilience of Rhodobacter sphaeroides cytochrome bc1 to heme c1 ligation changes. Biochemistry 45, 14247-14255.
61. Osyczka, A., Zhang, H., Mathe, C., Rich, P. R., Moser, C. C., and Dutton, P. L. (2006) Role of the PEWY glutamate in hydroquinone-quinone oxidation-reduction catalysis in the Qo site of cytochrome bc1. Biochemistry 45, 10492-10503.
62. Lee, D-W., Oztruk, Y., Mamedova, A., Osyczka, A., Cooley, J. W., and Daldal, F. (2006) A functional hybrid between the cytochrome bc1 complex and its physiological membrane anchored electron acceptor cytochrome cy in Rhodobacter capsulatus. Biochim. Biophys. Acta 1757, 346-352.
63. Moser, C. C., Osyczka, A., and Dutton, P. L. (2005) Short-circuit proofing Mitchell's Q cycle, in: "Photosynthesis: Fundamental Aspects to Global Perspectives", (Bruce, D., and van der Est A., ed.) Allen Press, 427-430.
64. Nanda, V., Rosenblatt, M. M., Osyczka, A., Kono, H., Getahun, Z., Dutton, P. L., Saven, J. G., and DeGrado, W. F. (2005) De novo design of a redox active minimal rubredoxin mimic. J. Am. Chem. Soc. 127, 5804-5805.
65. Osyczka A., Moser C. C., and Dutton P. L. (2005) Fixing the Q cycle. Trends Bioch. Sci. 30, 176-182.
66. Iwaki, M., Yakovlev, G., Hirst, J., Osyczka, A., Dutton, P. L., Marshall, D., and Rich, P. R. (2005) Direct observation of redox-linked histidine protonation changes in the iron-sulfur protein of cytochrome bc1 complex by ATR-FTIR spectroscopy. Biochemistry 44, 4230-4237.
67. Iwaki, M., Osyczka, A., Moser, C. C., Dutton, P. L., and Rich, P. R. (2004) ATR-FTIR spectroscopy studies of iron-sulfur protein and cytochrome c1 in Rhodobacter capsulatus cytochrome bc1. Biochemistry 43, 9477-9486.
68. Ghirlanda, G., Osyczka, A., Liu, W., Antolovich, M., Smith, K. M., Dutton, P. L., Wand, A. J., and DeGrado, W. F. (2004) De novo design of a D2-symmetrical protein that reproduces the di-heme 4-helix bundle in cytochrome bc1. J. Am. Chem. Soc. 126, 8141-8147.
69. Osyczka, A., Moser, C. C., Daldal, F., and Dutton, P. L. (2004) Reversible redox energy coupling in electron transfer chains. Nature 427, 607-612.
70. Osyczka, A., Moser, C. C., and Dutton, P. L. (2004) Novel cyanide inhibition at cytochrome c1 of Rhodobacter capsulatus cytochrome bc1. Biochim. Biophys. Acta 1655, 71-76.
71. Li, J., Osyczka, A., Conover, R. C., Johnson, M. K., Qin, H., Daldal, F., and Knaff, D. B. (2003) The role of acidic and aromatic amino acids in Rhodobacter capsulatus cytochrome c1. A site-directed mutagenesis study. Biochemistry 42, 8818-8830.
72. Li, J., Darrouzet, E., Dhawan, I. K., Johnson, M. K., Osyczka, A., Daldal, F., and Knaff, D. B. (2002) Spectroscopic and oxidation-reduction properties of Rhodobacter capsulatus cytochrome c1 and its M183K and M183H variants. Biochim. Biophys. Acta, 1556, 175-186.
73. Osyczka, A., Dutton, P. L., Moser, C. C., Darrouzet, E., and Daldal, F. (2001) Controlling the functionality of cytochrome c1 redox potentials in Rhodobacter capsulatus bc1 complex through disulfide anchoring of a loop and a β-branched amino acid near the heme-ligating methionine. Biochemistry 40, 14547-14556.
74. Pyka, J., Osyczka, A., Turyna, B., Blicharski, W., and Froncisz, W. (2001) EPR studies of iso-1-cytochrome c: effect of temperature on two-component spectra of spin label attached to cysteine at position 102 and 47. Eur. Biophys. J. 30, 367-373.
75. Osyczka, A., Nagashima, K. V. P., Sogabe, S., Miki, K., Shimada, K., and Matsuura, K. (2001) Different mechanisms of the binding of soluble electron donors to the photosynthetic reaction center of Rubrivivax gelatinosus and Blastochloris viridis. J. Biol. Chem. 276, 24108-24112.
76. Pyka, J., Osyczka, A., Turyna, B., Blicharski, W., and Froncisz, W. (1999) Probing iso-1-cytochrome c structure by site-directed spin labeling and electron paramagnetic resonance techniques. Acta Biochimica Polonica 46, 889-899.
77. Osyczka, A., Nagashima, K. V. P., Sogabe, S., Miki, K., Shimada, K., and Matsuura, K. (1999) Comparison of the binding sites for high-potential iron-sulfur protein and cytochrome c on the tetraheme cytochrome subunit bound to the bacterial photosynthetic reaction center. Biochemistry 38, 15779-15790.
78. Osyczka, A., Nagashima, K. V. P., Shimada, K., and Matsuura, K. (1999) Interaction site for high-potential iron-sulfur protein on the tetraheme cytochrome subunit bound to the photosynthetic reaction center of Rubrivivax gelatinosus. Biochemistry 38, 2861-2865.
79. Osyczka, A., Nagashima, K. V. P., Sogabe, S., Miki, K., Yoshida, M., Shimada, K., and Matsuura, K. (1998) Docking site for soluble electron carriers on the tetraheme cytochrome subunit bound to the bacterial photosynthetic reaction center, in: "Photosynthesis: Mechanisms and Effects" (Garab, G. ed.), vol. II, Kluwer Academic Publishers, Dordrecht, 901-904.
80. Osyczka, A., Nagashima, K. V. P., Sogabe, S., Miki, K., Yoshida, M., Shimada, K., and Matsuura, K. (1998) Interaction site for soluble cytochromes on the tetraheme cytochrome subunit bound to the bacterial reaction center mapped by site-directed mutagenesis. Biochemistry 37, 11732-11744.
81. Turyna, B., Osyczka, A., Kostrzewa, A., Blicharski, W., Enghild, J. J., and Froncisz, W. (1998) Preparation and electron paramagnetic resonance characterization of spin labeled monoderivatives of horse cytochrome c. Biochim. Biophys. Acta 1386, 50-58.
82. Osyczka, A., Yoshida, M., Nagashima, K. V. P., Shimada, K., and Matsuura, K. (1997) Electron transfer from high-potential iron-sulfur protein and low-potential cytochrome c-551 to the primary donor of Rubrivivax gelatinosus reaction center mutationally devoid of the bound cytochrome subunit. Biochim. Biophys. Acta 1321, 93-99.
83. Hilczer, W., Goslar, J., Gramza, M., Hoffmann, S. K., Blicharski, W., Osyczka, A., Turyna, B., and Froncisz, W. (1995) A resonance enhancement of the phase relaxation in the electron spin echo of nitroxide covalently attached to cytochrome c. Chem. Phys. Lett. 247, 601-606.
84. Osyczka, A., and Turyna, B. (1995) Cytochrome c conformations and its interactions with cytochrome c oxidase. Advances in Biochemistry 41, 59-66.
85. Osyczka, A., and Turyna, B. (1994) Site-specific incorporation of unnatural amino acids into proteins. Advances in Cell Biology 21, 175-185.