Statistical methods for the Ames Salmonella assay: a review

The Ames Salmonella assay remains the most widely used in vitro genotoxicity assay. Several statistical methods have been proposed for its analysis [B.H. Margolin, N. Kaplan, E. Zeiger, Statistical analysis of the Ames Salmonella/microsome test, Proc. Natl. Acad. Sci., 78 (1981) 3779–3783; L.E. Myers, N.H. Saxton, L.I. Southerland, T.J. Wolff, Regression analysis of Ames test data, Environ. Mol. Mutagen., 3 (1981) 575–586; A.G. Stead, V. Hasselblad, J.P. Creason, L. Claxton, Modelling the Ames test, Mutation Res., 85 (1981) 13–27; L. Bernstein, J. Kaldor, J. McCaan, M.C. Pike, An empirical approach to the statistical analysis of mutagenesis data from the Salmonella test, Mutation Res., 97 (1982) 267–281; N.E. Breslow, Extra-Poisson variation in log-linear models, Appl. Stat., 33 (1984) 38–44; J. Wahrendorf, G.A.T. Mahon, M. Schumacher, A nonparametric approach to the statistical analysis of mutagenicity data, Mutation Res., 147 (1985) 5–13; D.G. Simpson, B.H. Margolin, Recursive nonparametric testing for dose–response relationships subject to downturns at high doses, Biometrika, 73 (1986) 589–596; D.G. Simpson, B.H. Margolin, Nonparametric testing for dose–response curves subject to downturns: Asymptotic power considerations, Annals Stat., 18 (1990) 373–390.]. In this paper we review recent literature to see what statistical methods are in fact employed for the analysis of the Ames assay. We then note that these methods can be classified into a common category in the framework of Haynes and Eckardt's mutation induction kinetics model [R.H. Haynes, F. Eckardt, Mathematical analysis of mutation induction kinetics, in: F.J. de Serres, A. Hollaender (Eds.), Chemical Mutagens, Principles and Methods for Their Detection, Vol. 6, Plenum, New York, 1980, pp. 271–307]. The value in knowing this is that most methods of analysis considered here will likely exhibit common statistical behavior. These analyses are computationally intensive, e.g., [B.H. Margolin, N. Kaplan, E. Zeiger, Statistical analysis of the Ames Salmonella/microsome test, Proc. Nat. Acad. Sci., 78 (1981) 3779–3783], hence the ready availability of computer programs is essential if biologists are to use these methods. We briefly review two statistical software programs that are available in the public domain, and describe in detail a third program, Salm, [B.H. Margolin, N. Kaplan, E. Zeiger, Statistical analysis of the Ames Salmonella/microsome test, Proc. Nat. Acad. Sci., 78 (1981) 3779–3783; B.H. Margolin, B.S. Kim, K. Risko, The Ames Salmonella/microsome assay: Issues of inference and validation, J. Amer. Stat. Assoc., 84 (1989) 651–661]. The Salm program is obtainable through the file transfer protocol (ftp) or using a WWW browser. Finally, we discuss two statistical consequences of naively applying the two-fold rule, a method of analysis employed by a number of researchers.     

Other short reviews

Wiedemann, A.M., Dennis, L.R.J. & Smith, F.H. 1999. Plants of the Oregon coastal dunes. (New edition). 120 pp. Oregon State University Press, Corvallis, OR. ISBN 0–87071–457–0. (paperback) Price: USD 12.95.     

Immunogobulin-lipid interaction: A model membrane study

We recently presented evidence (Vandenbranden, M., De Coen, J.L., Jeener, R., Kanarek, L. and Ruysschaert, J.M. (1981) Mol. Immunol. 8, 621–631) for the existence of two conformational rabbit serum IgG immunoglobulin isomers. In the present report, their capacity to interact with lipid is investigated in model membranes. (1) One isomer, IgG(H), behaves like several intrinsic membrane proteins: it induces a large surface pressure increase when injected under a lipid monolayer in the close packed state and increases by 20-fold the conductance of a planar bilayer. The other isomer, IgG(S) doesn't interact significantly with the lipids. (2) IgG(H) marked a preference for monolayers made of lipids with a negatively charged polar headgroup and bearing unsaturations in their acyl chains. Penetration is stronger with lipid monolayer in the fluid state than in the rigid state. (3) As previously shown (Vandenbranden, M., De Coen, J.L., Jeener, R., Kanarek, L. and Ruysschaert, J.M. (1981) Mol. Immunol. 18, 621–631), circular dichroïsm spectra and antigen precipitation tests don't allow to detect any difference in the overall secondary conformation and antigen recognition properties of the two isomers. (4) Papaïn cleavage of the hinge region suppresses the hydrophobic properties of IgG towards lipid monolayers. (5) The hypothesis of a binding of the hinge region with the lipid bilayer is discussed.     

Effect of membrane cholesterol enrichment or depletion on the partition behavior of human erythrocytes in dextran-poly(ethylene glycol) aqueous phases

It has previously been shown that by appropriate manipulation of polymer concentrations and ionic composition and concentration one can select whether charge-associated or lipid-related membrane surface properties are reflected by cell partition in dextran-poly(ethylene glycol) aqueous two-phase systems (Walter, H. (1977) in Methods of Cell Separation ((Catsimpoolas, N., ed.), Vol. 1, pp. 307–354, Plenum Press, New York). In the current experiments we have studied the partition behavior of human erythrocytes and found that not only lipid-related but also charge-associated membrane properties are altered as a consequence of cholesterol-enrichment or -depletion. Results further indicate that, just as cell partition in charged phase systems reflects membrane charge-associated properties not readily measured by means other than partition (Brooks, D.E., Seaman, G.V.F. and Walter, H. (1971) Nat. New Biol. 234, 61–62; Walter, H., Tung, R., Jackson, L.J. and Seaman, G.V.F. (1972) Biochem. Biophys. Res. Commun. 48, 565–571), cell partition in uncharged phases reflects membrane lipid-related properties also not readily measured by other means.     

The sculpture and morphology of postcranial dermal armor plates and associated bones in gasterosteiforms and syngnathiforms inhabiting Estonian coastal waters

Lees, J., Märss, T., Wilson, M. V. H., Saat, T. and ?pilev, H. 2011. The sculpture and morphology of postcranial dermal armor plates and associated bones in gasterosteiforms and syngnathiforms inhabiting Estonian coastal waters. ―Acta Zoologica (Stockholm) 93 : 422–435. Five fish species inhabiting Estonian coastal waters (Gasterosteus aculeatus L., Pungitius pungitius (L.), and Spinachia spinachia (L.) of the order Gasterosteiformes and Syngnathus typhle L. and Nerophis ophidion (L.) of the order Syngnathiformes) are described on the basis of the sculpture and morphology of their postcranial dermal armor plates, as revealed and illustrated by SEM images. This study shows that the shapes of these superficial skeletal elements vary by species as well as by their position on the body, whereas the sculpture on the bones is taxon specific. The detailed features allow the identification of isolated fossil and subfossil remains and show promise for future systematics studies.     

Botulinum Neurotoxin Type A: Limited Proteolysis by Endoproteinase Glu-C and α-Chymotrypsin Enhanced Following Reduction; Identification of the Cleaved Sites and Fragments

Botulinum neurotoxin (NT) serotype A is a ～150-kDa dichain protein. Posttranslational nicking of the single-chain NT (residues Pro 1–Leu 1295) by the protease(s) endogenous to Clostridium botulinum excises 10 residues, leaving Pro 1–Lys 437 and Ala 448–Leu 1295 in the ～50-kDa light (L) and ～100-kDa heavy (H) chains, respectively, connected by a Cys 429–Cys 453 disulfide and noncovalent bonds [Krieglstein et al. (1994), J. Protein Chem. 13, 49–57]. The L chain is a metalloprotease, while the amino- and carboxy-terminal halves of the H chain have channel-forming and receptor-binding activities, respectively [Montecucco and Schiavo (1995), Q. Rev. Biophys. 28, 423–472]. Endoproteinase Glu-C and α-chymotrypsin were used for controlled digestion at pH 7.4 of the ～150-kDa dichain NT and the isolated ～100-kDa H chain (i.e., freed from the L chain) in order to map the cleavage sites and isolate the proteolytic fragments. The dichain NT appeared more resistant to cleavage by endoproteinase Glu-C than the isolated H chain. In contrast, the NT with its disulfide(s) reduced showed rapid digestion of both chains, including a cleavage between Glu 251 and Met 252 (resulting in ～30- and ～20-kDa fragments of the L chain) which was not noted unless the NT was reduced. Interestingly, an adjacent bond, Tyr 249–Tyr 250, was noted earlier [DasGupta and Foley (1989), Biochimie 71, 1193–1200] to undergo “self-cleavage” following reductive separation of the L chain from the H chain. The site Tyr–Tyr–Glu–Met (residues 249–252) appears to become exposed following reduction of Cys 429–Cys 453 disulfide. Identification of Glu 669–Ile 670 and Tyr 683–Ile 684 as protease-susceptible sites demonstrated for the first time that at least two peptide bonds in the segment of the H chain (residues 659–684), part of which (residues 659–681) is thought to interact with the endosomal membranes and forms channels [Oblatt-Montal et al., (1995), Protein Sci. 4, 1490–1497], are exposed on the surface of the NT. Two of the fragments of the H chain we generated and purified by chromatography are suitable for structure–function studies; the ～85- and ～45-kDa fragments beginning at residue Leu 544 and Ser 884, respectively (both extend presumably to Leu 1295) contain the channel-forming segment and receptor-binding segments, respectively. In determining partial amino acid sequences of 10 fragments, a total of 149 amino acids in the 1275-residue NT were chemically identified.     

A new species of Lathyrus L. (section Cicercula; Fabaceae) from Turkey

A new species, Lathyrus egirdiricus H.Genc & A.Sahin (section Cicercula; Fabaceae), is described from Turkey, with illustrations and taxonomic comments. Characteristics of the species are compared with those of the related species Lathyrus hirsutus L., L. stenophyllus Boiss. & Heldr., L. sativus L., L. cassius Boiss. and L. gorgoni Parl., from which it differs mainly in the shape, length, width and venation of leaflets, length and width of the stipule, flower colour, legume and style length. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 301–305.     

Solution studies of staphylococcal nuclease H124L. 2. 1H, 13C, and 15N chemical shift assignments for the unligated enzyme and analysis of chemical shift changes that accompany formation of the nuclease-thymidine 3',5'-bisphosphate-calcium ternary complex.

Accurate 1H, 15N, and 13C chemical shift assignments were determined for staphylococcal nuclease H124L (in the absence of inhibitor or activator ion). Backbone 1H and 15N assignments, obtained by analysis of three-dimensional 1H-15N HMQC-NOESY data [Wang, J., Mooberry, E.S., Walkenhorst, W.F., & Markley, J. L. (1992) Biochemistry (preceding paper in this issue)], were refined and extended by a combination of homo- and heteronuclear two-dimensional NMR experiments. Staphylococcal nuclease H124L samples used in the homonuclear 1H NMR studies were at natural isotopic abundance or labeled randomly with 2H (to an isotope level of 50%); nuclease H124L samples used for heteronuclear NMR experiments were labeled uniformly with 15N (to an isotope level greater than 95%) or uniformly with 13C (to an isotope level of 26%). Additional nuclease H124L samples were labeled selectively by incorporating single 15N- or 13C-labeled amino acids. The chemical shifts of uncomplexed enzyme were then compared with those determined previously for the nuclease H124L.pdTp.Ca2+ ternary complex [Wang, J., LeMaster, D. M., & Markley, J.L. (1990) Biochemistry 29, 88-101; Wang, J., Hinck, A.P., Loh, S. N., & Markley, J.L. (1990) Biochemistry 29, 102-113; Wang, J., Hinck, A.P., Loh, S.N., & Markley, J.L. (1990) Biochemistry 29, 4242-4253]. The results reveal that the binding of pdTp and Ca2+ induces large shifts in the resonances of several amino acid segments. These chemical shift changes are interpreted in terms of changes in backbone torsion angles that accompany the binding of pdTp and Ca2+; changes at the binding site appear to be transmitted to other regions of the molecule through networks of hydrogen bonds.     

Trade-off between pre and post-copulatory traits depends on locomotor activity in male Tribolium castaneum beetles

Locomotor performance is an indicator of dynamic exercise; thus, it is a central trait in many animal behaviours. Although higher locomotor endurance may increase male reproductive success (e.g., in mate searching and male–male contests), investment in other male reproductive traits (e.g., male attractiveness and sperm competition) may be decreased through energy consumption due to higher activity levels. Here, I investigated male attractiveness, mating success, and paternity success using males of the red flour beetle Tribolium castaneum selected for higher (H) and lower (L) locomotor endurance. Although there was no difference in male attractiveness between the selection regimes, H males had significantly higher mating success than L males. Conversely, L males had significantly higher paternity success than H males. Therefore, there was a trade-off between mating success and paternity success among the selection regimes, suggesting that locomotor endurance affects male reproduction in T. castaneum, and individual variation of locomotor endurance may be maintained within a population.     

Plasma prolactin levels in male homosexuals

Plasma prolactin values of 20 male homosexuals of Kinsey rating 6 were compared with plasma prolactin values of 15 male heterosexuals of Kinsey rating 0. There was no difference in mean plasma prolactin value between the two groups. These findings are at variance with those reported by Kolodny et al. [Kolodny, R. C., Jacobs, L. S., Masters, W. H., Toro, G., and Daughaday, W. H. (1971a). Plasma gonadotrophins and prolactin in male homosexuals. Lancet2, 18–20] in which plasma prolactin was found to be elevated in individuals of Kinsey rating 6 as compared to heterosexual controls. The present investigation, therefore, fails to confirm a relationship between sexual orientation in males and plasma prolactin level.     

SOME PIECES OF THE AFRICAN GENOME PUZZLE IN HIBISCUS SECT. FURCARIA (MALVACEAE)

New chromosome counts are reported for four African diploid species of Hibiscus L. sect. Furcaria DC: H. greenwayi Bak. f., H. hiernianus Exell et Mendonça, and H. mechowii Garcke, n = 18; and H. berberidifolius A. Rich., 2n = 36. Chromosome behavior is described in seven new hybrid combinations. Hibiscus greenwayi is shown to carry an A genome. Hibiscus hiernianus and H. mastersianus have similar genomes which are not homologous with that of H. mechowii. New and earlier data are integrated to elucidate genome relationships among 13 taxa–each of the four tetraploid species has a different formula encompassing 2 of 6 mutually nonhomologous genomes, A, B, G, H, X and Y (H. acetosella Welw. ex Hiern = AABB; H. meeusei Exell = AAXX; H. sabdariffa L. = AAYY; H. rostellatus Guill. et Perr. = GGHH). Diploid donors of A, B, G, X and Y are proposed on the basis of plant, flower and pollen morphology. Diploid carriers of A (H. asper Hook. f., H. cannabinus L., H. greenwayi), B (H. surattensis L.) and G (H. sudanensis Hochr.) have been verified cytologically. Cytological confirmation of X (H. hiernianus, H. mastersianus Hiern) and Y (H. mechowii) carriers is incomplete. No putative diploid carrier of H is at hand. Genome affinities of H. berberidifolius are unknown.     

Pollen morphology of Lathyrus (Leguminosae) taxa belonging to Lathyrus, Orobastrum and Cicercula sections from Turkey

The pollen morphology of 20 wild taxa belonging to Lathyrus (Syn: Eulathyrus), Orobastrum (Taub.) Boiss. and Cicercula (Medic.) Gren. & Godr. sections of Lathyrus L. grown in Turkey (L. rotundifolius Wild. subsp. miniatus (Bieb. ex Steven) P.H. Davis, L. grandiflorus Sibth. & Sm., L. saxatilis (Vent.) Vis., L. vinealis Boiss. & No?, L. inconspicuus L. var. inconspicuus, L. inconspicuus var. stenophyllus (Boiss.) Rech. f., L. tauricola P.H. Davis, L. woronowii Bornm., L. hierosolymitanus Boiss., L. cassius Boiss., L. gorgoni Parl. var. gorgoni, L. pseudo-cicera Pamp., L. sativus L., L. blepharicarpus Boiss., L. stenophyllus Boiss. & Heldr., L. belinensis Maxted & Goyder, L. phaselitanus Hub.-Mor. & P.H.Davis, L. chrysanthus Boiss., L. chloranthus Boiss., and L. trachycarpus (Boiss.) Boiss were examined by light microscopy (LM) and scanning electron microscopy (SEM) in this study. The pollen grains were 3-zonocolporate, spheroidal, subprolate, and prolate (P/E?=?0.99–1.48) types, and were medium in size (equatorial view: rectangular or elliptical-obtuse-convex; polar view: circular, triangular and quinquangular-obtuse-convex). The smallest pollen grains belonged to L. tauricola (P?=?30.94/E?=?31.20) and the largest to L. grandiflorus (P?=?50.60/E?=?36.40). The ornamentation was reticulate and reticulate-granulate in the mesocolpium, and usually psilate in the apocolpium. Some photographs included in this work were taken using both LM and SEM.     

Diffusion in plant cuticles as affected by temperature and size of organic solutes: similarity and diversity among species

Mobilities of lipophilic organic solutes in cuticular membranes (CM) isolated from mature leaves of Citrus aurantium L., Citrus grandis L., Hedera helix L., IIex aquifolium L., Ilex paraguariensis St.-Hil., Mains domestica Borkh., Prunus armeniaca L., Primus laurocerasus L., Pyrus communis L., Pyrus pyrifolia (Burm. f.) Nakai, Stephanotis florihunda Brongn. and Strophantus gratus Baill. were measured over a temperature range of 15–78°C. In this range, solute mobilities increased up to 1000-fold, which corresponds to temperature coefficients Q₁₀ of 3 (IAA in P. armeniaca) to 14 (cholesterol in H. helix). For most species, Arrhenius graphs showed good linearity up to 40°C, and up to 78°C for some species, while for others activation energies declined with increasing temperature. However, no distinct phase transitions caused by sudden structural changes in the CM were observed. In three species we examined whether heating to 70°C changed solute mobility irreversibly by comparing Arrhenius graphs for two successive experiments with the same CM. The two graphs were very similar for P. laurocerasus, while mobilities in the second graph were somewhat reduced for C. aurantium and greatly increased (at 25 and 35°C) for H. helix. This indicates rearrangements of at least some wax constituents when heated to high temperatures. The activation energies of diffusion (E_D) ranged from 75 to 189 KJ mol^?11 depending on species and solute size. Size selectivity and variability between cuticles decreased with increasing temperature, and this is caused by differences in (E_D). An excellent correlation between the pre-exponential factor of the Arrhenius equation and E_D was observed, which is evidence that organic solutes differing greatly in molecular size (130–349 cm³ mol^?1) and cuticle/water partition coefficient (25–10⁸) use similar diffusion paths in the CM of all 12 plant species tested. Diffusion occurs in regions with identical physicochemical properties and differs only in magnitude.     

Regulatable expression of p21-activated kinase-1 promotes anchorage-independent growth and abnormal organization of mitotic spindles in human epithelial breast cancer cells

Stimulation of growth factor signaling has been implicated in the development of invasive phenotypes and the activation of p21-activated kinase (Pak1) in human breast cancer cells (Adam, L., Vadlamudi, R., Kondapaka, S. B., Chernoff, J., Mendelsohn, J., and Kumar, R. (1998) J. Biol. Chem. 273, 28238-28246; Adam, L., Vadlamudi, R., Mandal, M., Chernoff, J., and Kumar, R. (2000) J. Biol. Chem. 275, 12041-12050). To study the role of Pak1 in the regulation of motility and growth of breast epithelial cells, we developed human epithelial MCF-7 clones that overexpressed the kinase-active T423E Pak1 mutant under an inducible tetracycline promoter or that stably expressed the kinase-active H83L,H86L Pak1 mutant, which is deficient in small GTPase binding sites. The expression of both T423E and H83L,H86L Pak1 mutants in breast epithelial cells was accompanied by increased cell motility without any apparent effect on the growth rate of cells. The T423E Pak1 mutant was primarily localized to filopodia, and the H83L,H86L Pak1 mutant was primarily localized to ruffles. Cells expressing T423E Pak1 exhibited a regulatable stimulation of mitogen-activated protein kinase and Jun N-terminal kinase activities. The expression of kinase-active Pak1 mutants significantly stimulated anchorage-independent growth of cells in soft agar in a preferential mitogen-activated protein kinase-sensitive manner. In addition, regulatable expression of kinase-active Pak1 resulted in an abnormal organization of mitotic spindles characterized by appearance of multiple spindle orientations. We also provide evidence to suggest a close correlation between the status of Pak1 kinase activity and base-line invasiveness of human breast cancer cells and breast tumor grades. This study is the first demonstration of Pak1 regulation of anchorage-independent growth, potential Pak1 regulation of invasiveness, and abnormal organization of mitotic spindles of human epithelial breast cancer cells.     

Oxidative activation of protein kinase Cgamma through the C1 domain. Effects on gap junctions

The accumulation of reactive oxygen species (ROS, for example H2O2) is linked to several chronic pathologies, including cancer and cardiovascular and neurodegenerative diseases (Gate, L., Paul, J., Ba, G. N., Tew, K. D., and Tapiero, H. (1999) Biomed. Pharmacother. 53, 169-180). Protein kinase C (PKC) gamma is a unique isoform of PKC that is found in neuronal cells and eye tissues. This isoform is activated by ROS such as H2O2. Mutations (H101Y, G118D, S119P, and G128D) in the PKCgamma Cys-rich C1B domain caused a form of dominant non-episodic cerebellar ataxia in humans (Chen, D.-H., Brkanac, Z., Verlinde, C. L. M. J., Tan, X.-J., Bylenok, L., Nochli, D., Matsushita, M., Lipe, H., Wolff, J., Fernandez, M., Cimino, P. J., Bird, T. D., and Raskind, W. H. (2003) Am. J. Hum. Genet. 72, 839-849; van de Warrenburg, B. P. C., Verbeek, D. S., Piersma, S. J., Hennekam, F. A. M., Pearson, P. L., Knoers, N. V. A. M., Kremer, H. P. H., and Sinke, R. J. (2003) Neurology 61, 1760-1765). This could be due to a failure of the mutant PKCgamma proteins to be activated by ROS and to subsequently inhibit gap junctions. The purpose of this study was to demonstrate the cellular mechanism of activation of PKCgamma by H2O2 and the resultant effects on gap junction activity. H2O2 stimulated PKCgamma enzyme activity independently of elevations in cellular diacylglycerol, the natural PKC activator. Okadaic acid, a phosphatase inhibitor, did not affect H2O2-stimulated PKCgamma activity, indicating that dephosphorylation was not involved. The reductant, dithiothreitol, abolished the effects of H2O2, suggesting a direct oxidation of PKCgamma at the Cys-rich C1 domain. H2O2 induced the C1 domain of PKCgamma to translocate to plasma membranes, whereas the C2 domain did not. Direct effects of H2O2 on PKCgamma were demonstrated using two-dimensional SDS-PAGE. Results demonstrated that PKCgamma formed disulfide bonds in response to H2O2. H2O2-activated PKCgamma was targeted into caveolin-1- and connexin 43-containing lipid rafts, and the PKCgamma phosphorylated the connexin 43 gap junction proteins on Ser-368. This resulted in disassembly of connexin 43 gap junction plaques and decreased gap junction activity. Results suggested that H2O2 caused oxidation of the C1 domain, activation of the PKCgamma, and inhibition of gap junctions. This inhibition of gap junctions could provide a protection to cells against oxidative stress.     

Hydrogen-1 NMR evidence for three interconverting forms of staphylococcal nuclease: effects of mutations and solution conditions on their distribution

It has been known for several years that 1H NMR spectra of the enzyme staphylococcal nuclease contain resonances due to conformational heterogeneity [Markley, J. L., Williams, M. N., & Jardetzky, O. (1970) Proc. Natl. Acad. Sci. U.S.A. 65, 645-651]. One source of conformational heterogeneity has been attributed recently to cis/trans isomeriation of the Lys116-Pro117 peptide bond [Evans, P. A., Dobson, C. M., Kautz, R. A., Hatfull, G., & Fox, R. O. (1987) Nature (London) 329, 266-268]. In this paper we present evidence for three interconverting folded forms of nuclease. Forms N and N' are monomeric; form N" appears at higher nuclease concentrations and probably corresponds to dimerized enzyme. Saturation transfer was used to demonstrate that exchange occurs between the denatured state and N". The effects of temperature, pH, and Ca2+ and nucleotide binding on NMR spectra of nuclease were examined. When the temperature is increased or the pH is lowered, form N' is favored relative to N. Binding of a competitive inhibitor (thymidine 3',5'-bisphosphate plus calcium ion) strongly favors one form of nuclease. 1H NMR spectra of wild-type nuclease, the single-mutant nucleases L89F and H124L, and the double-mutant nuclease F76V+H124L were compared. In the unligated proteins, the equilibrium constant for the conformational equilibrium N in equilibrium with N' is approximately 0.1 in wild-type nuclease and nuclease H124L; by contrast, this equilibrium constant is about 0.7 in nuclease L89F and 1.2 in nuclease F76V+H124L under similar conditions.     

Archives of Phytopathology and Plant Protection

Abstract

Horsfall, J. G. (Ed): Annual Review of Phytopathology. Vol. 5, 1967, VII + 470 S., Leinen, 9,00 $, Palo Alto, Calif., Annual Reviews, Inc. Reviewed by K. Naumann.

Clifton, C. E. (Ed.): Annual Review of Microbiology. Vol. 21, 1907, VII + 729 S., mit Abb. u. Tab., Leinen, 9,00 $, Palo Alto (Ca.), Annual Reviews Inc. Reviewed by K. Naumann.

Machlis, L.; Briggs, W. R.; Park, R.B. (Ed.): Annual Review of Plant Physiology. 19. Bd., Palo Alto, Annual Reviews, Inc., 1908, 555 S., 20 Abb., 22 Tab., Lw. Reviewed by H. Wolffgang.

Gale, E. F.: Promotion and prevention of synthesis in bacteria. 1968, 99 S., 29 Abb., 6 Tab., Leinen, $ 5,75, Syracuse, Syracuse University Press Reviewed by L. Behr.

O. V.: Review of Applied Mycology, Plant Host — Pathogen Index to Vol. 1–40 (1922–1901). Kew, (Surrey), Commonwealth Mycologic. Inst., 1908, 820 S., brosch., 10 £ 10 s. Reviewed by M. Klinkowski.

Backhausz, R. (Ed.): Proceedings of the fourth Congress of the Hungarian Association of Microbiologists (Budapest 1964). 1966, XVIII + 405 S., mit Abb. u. Tab., Leinen, 250 Ft., Budapest, Akadémiai Kiadó Reviewed by P. Wolf.

Pepfler, H. J.: Microbial technology. 1907, 454 S., 45 Abb., 78 Tab., Leinen, S 15.50, Amsterdam, Reinhold Europe Reviewed by Erika Griesbach.     

BOOK REVIEWS

Book reviewed in this article:
P rete , F. R., W ells , H., W ells , P. H. and H urd , L. E. 1999. The praying mantids .