Letters

BIOCHEMICAL INDIVIDUALITY: THE BASIS FOR THE GENETOTROPHIC CONCEPT: Roger J. Williams, John Wiley &; Sons, New York, 1956, 214 pp.

THE BIOLOGICAL BASIS OF HUMAN FREEDOM: Theodosius Dobzhansky, Columbia University Press, New York 1956, 139 pp.

COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY, Volume XX, Population Genetics: The Nature and Causes of Genetic Variability in Populations. The Biological Laboratory, Cold Spring Harbor, L. I., New York, 1955, 346 pp.

HERITABLE DISORDERS OF CONNECTIVE TISSUE. Victor A. McKusick, Mosby Co., St. Louis, 1956, 224 pp. $7.50.

THE CHEMICAL BASIS OF HEREDITY: Edited by William D. McElroy and Bentley Glass. The Johns Hopkins Press, Baltimore, 1957, 848 pp.

THE POPULATION OF JAMAICA: George W. Roberts, Cambridge University Press, Cambridge, 1957.     

Distribution of genes affecting characteristics of the population

THE CHANGING POPULATION OF THE UNITED STATES: Conrad Taeuber and Irene B. Taeuber. A Volume in the Census Monograph Series. John Wiley and Sons, Inc., New York; Chapman and Hall, Limited, London; for the Social Science Research Council in cooperation with the U. S. Department of Commerce, Bureau of the Census; 1958; xi, 357 pp.; $7.75.

VARIABLES RELATED TO HUMAN BREAST CANCER: Elving Anderson, Harold J. GOODMAN and SHELDON C. REED. University of Minnesota Press, Minneapolis, 1958, 172 pp., 41 text, tables, 53 appendix tables, 7 figures. $4.00.

THE POPULATION AHEAD, Edited by Roy G. Francis. University of Minnesota Press, Minneapolis, 1958, x, 160 pp.

ABORTION IN THE UNITED STATES: Mary Calderone, M. D. (Editor). Hoeber‐Harper, New York, 1958, 224 pp. $5.50.

DIFFERENTIAL PSYCHOLOGY: Anne Anastasi. The Macmillan Company, New York, 1958 (3rd Edition), 664 pp + xii.

FIVE YEARS OF FAMILY PLANNING IN THE COUNTRYSIDE: Baljit Singh. J. K. Institute Monograph No. 6, J. K. Institute of Sociology &; Human Relations, Lucknow University. 1958. 118 pp.

POPULATION; AN INTERNATIONAL DILEMMA. A Summary of the Proceedings of the Conference on Population Problems— 1956–1957. Frederick Osborn. New York, Population Council, 1958. Pp. ix + 97. $2.00.     

Genetic‐hygienic impairment through incestuous matings

THE EFFECT OF EXPOSURE TO THE ATOMIC BOMBS ON PREGNANCY TERMINATION IN HIROSHIMA AND NAGASAKI: J. V. Neel and W. J. Schull, Publication No. 461, National Academy of Sciences—National Research Council, Washington, 1956, 241 pp., $2.00.

DEMOGRAPHIC ANALYSIS: SELECTED READINGS: Edited by Joseph J. Spengler and Otis Dudley Duncan. The Free Press, Glencoe, Illinois, 1956. xvi, 820 pp. $9.50.

POPULATION THEORY AND POLICY: SELECTED READINGS: Edited by Joseph S. Spengler and Otis Dudley Duncan. The Free Press, Glencoe, Illinois, 1956. x, 522 pp. $7.50.

HEALTH AND DEMOGRAPHY: Halbert L. Dunn; U. S. Department of Health, Education, and Welfare, Public Health Service, Bureau of State Services, National Office of Vital Statistics; Washington, October, 1956, 94 pp., $.50.

SOCIAL CHARACTERISTICS OF URBAN AND RURAL COMMUNITIES, 1950: Otis Dudley Duncan and Albert J. Reiss, Jr., John Wiley and Sons, Inc., New York, 1956, XVIII + 421 pp. $6.50.

THE PSYCHOLOGY OF HUMAN DIFFERENCES: Leona E. Tyler. 2nd Edition. New York, Appleton‐Century‐Crofts, 1956. pp. VIII + 562.     

Abstracts

BIOFEEDBACK AND SELF‐CONTROL, 1970. Edited by Theodore Barber, Leo V. Di‐Cara, Joe Kamiya, Neal E. Miller, David Shapiro, and Johann Stoyva. Aldine Press, Chicago, 1971. 546 pp. $12.00.

INSANITY AND IDIOCY IN MASSACHUSETTS. REPORT OF THE COMMISSION ON LUNACY, 1855: By Edward Jarvis. Harvard University Press, Cambridge, Mass., 1971. 213 pp. $9.00.

METRIC TRENDS IN HOMINID DENTAL EVOLUTION: By Milford H. Wolpoff. Studies in Anthropology No. 2, Case Western Reserve University Press, Cleveland, 1971. 244 pp. $5.95.

CULTURE AND POPULATION: A COLLECTION OF CURRENT STUDIES: Edited by Steven Polgar. Carolina Population Center, Chapel Hill, North Carolina, 1971. 19S pp. $1.50, paperback.

AN INTRODUCTION TO ANTHROPOLOGY: By Ralph L. Beals and Harry Hoijer. Fourth Edition. The Macmillan Company, New York, 1971. 711 pp. $10.95.

CARMICHAEL'S MANUAL OF CHILD PSYCHOLOGY. Edited by Paul H. Mussen. John Wiley and Sons, Inc., New York, 1970. Two vols: Vol. 1, 1519 pp., $30.00; Vol. 2, 782 pp., $20.00. The set: $40.00.

MATHEMATICAL TOPICS IN POPULATION GENETICS: Edited by Ken‐ichi Kojima. Springer‐Verlag. New York, 1970. 400 pp. $18.70.

AMERICAN DAWN. A NEW MODEL OF AMERICAN PREHISTORY: By Louis A. Brennan. MacMillan, New York, 1970. 390 pp. $8.95.

PROGRESS IN MEDICAL GENETICS: Edited by Arthur G. Steinberg and Alexander G. Bearn. Vol. 7. Grune and Stratton, New York, 1970. 243 pp. $16.50.

CONGENITAL MALFORMATIONS: Edited by F. Clarke Fraser and V. A. McKusick. Excerpta Medica, Amsterdam, New York, 1970. 450 pp. $27.00.

THE HUMAN PLACENTA: By J. D. Boyd and W. J. Hamilton, W. Heffer and Sons Ltd., Cambridge, 1970. 365 pp. $43.83.

DENTAL HEALTH EDUCATION: Report of a WHO Expert Committee. World Health Organization Technical Report Series No. 449, World Health Organization, Geneva, 1970. 28 pp. $0.60.

MULTIPURPOSE SEROLOGICAL SURVEYS AND WHO SERUM REFERENCE BANKS: Report of a WHO Scientific Group. World Health Organization Technical Report Series No. 454. World Health Organization, Geneva, 1970. $1.75. 95 pp.

MENTAL HEALTH OF ADOLESCENTS AND YOUNG PERSONS. REPORT ON A TECHNICAL CONFERENCE: By A. R. May, J. H. Kahn, and B. Cronholm. World Health Organization, Geneva, 1971. 72 pp. $1.75.

BIOLOGICAL RESEARCH IN SCHIZOPHRENIA: Report of a WHO Scientific Group. World Health Organization, Geneva, 1970. 35 pp. $1.00.

EVOLUTION BY GENE DUPLICATION: By Susumu Ohno. Springer‐Verlag, New York‐Heidelberg‐Berlin, 1970. 160 pp. Hard cover, $9.90.

SYMBIOSIS. ORGANISMS LIVING TOGETHER: By Thomas C. Cheng. Pegasus, New York, 1970. 250 pp. $6.95 ($2.25, paperback).

MARIHUANA RECONSIDERED: By Lester Grinspoon. Harvard University Press, Cambridge, Mass. 1971. 443 pp. $9.95.

THE KHANNA STUDY: POPULATION PROBLEMS IN THE RURAL PUNJAB: By John B. Wyon and John E. Gordon. Harvard University Press, Cambridge, 1971. 437 pp. $14.00.     

A new heredity counseling service in Western Canada

ANIMAL GENETICS: Frederick B. Hutt. The Ronald Press Company, New York, 1964. 546 pp., $12.00.

INTERNATIONAL POPULATION CONFERENCE —CONCRAGES INTERNATIONAL DE LA POPULATION, OTTAWA, 1963: International Union for the Scientific Study of Population, Liège, 1964, 468 pp.

PROCEEDINGS OF THE 34TH SESSION, OTTAWA, 1963: Bulletin of the International Statistical Institute, Volume XL, Book 1, Toronto, 1964, pp. 319–494: Joint meetings with the International Union for the Scientific Study of Population.

THE CONCEPT OF RACE: Ashley Montagu, editor. Free Press of Glencoe, New York, 1964. 270 pp., $5.95.

PREGNANCY, CONCEPTION AND HEREDITY: Eric Weiser (Translated from the German by Therese Pol; So ensteht der Mensch: Von Zeugung und Vererbung, Ullstein Bücher, 1959). Blaisdell Publishing Co., New York, 1965. 148 pp., $1.50.     

Changes in American marriage patterns

HUMAN BEHAVIOR—AN INVENTORY OF SCIENTIFIC FINDINGS: Bernard Berelson and Gary A. Steiner. Harcourt, Brace &; World, Inc., New York, 1964, 712 pp. (with bibliographical and subject indexes), $11.00.

HEREDITY AND THE NATURE OF MAN: Theodosius Dobzhansky. Harcourt, Brace &; World, 1964, 179 pp., $4.75.

TEACHING GENETICS: C. D. Darlington and A. D. Bradshaw, editors. Philosophical Library, New York, 1963, 121 pp., illus., $7.50.

POPULATION DYNAMICS: CAUSES AND CONSEQUENCES OF WORLD DEMOGRAPHIC CHANGE: Ralph Thomlinson. Random House, New York, 1965, 576 pp., $8.50.

ADVANCES IN PLANNED PARENTHOOD: Aquiles J. Sobrero and Sarah Lewit, Editors. Schenkman Publishing Company, Inc., Cambridge, Mass. 1965, 151 pp., $5.95.     

Book reviews

COHORT FERTILITY: NATIVE‐WHITE WOMEN IN THE UNITED STATES: P. K. Whelpton, Princeton University Press, Princeton, 1954, XXV + 492 pp. $6.00.

COLONIAL DEVELOPMENT AND POPULATION IN TAIWAN: George W. Barclay, Princeton University Press, Princeton, New Jersey, 1954, xviii, 274 pp., $5.00.     

Book reviews

A METHODOLOGICAL, PSYCHIATRIC AND STATISTICAL STUDY OF A LARGE SWEDISH RURAL POPULATION: Acta Psychiatric et Neurologica Scandinavica Supplementum 89, Tage Larsson and Torsten Sjögren; Donald Burton, Translator; Ejnar Munksgarrd, Copenhagen, 1954, 250 pp.

GENETICS, BIOLOGICAL INDIVIDUALITY AND CANCER: Clarence C. Little, Stanford University Press, Stanford, California, 1954, ix, 115 pp., 27 figures, $2.50.     

The fertility of a sample of American elites

THE HUMAH CONDITION. HOW DID WE GET HERE AND WHERE ARE WE GOING?: By Frederick Osborn. Hugh Lauter Levin Associates, New York, 1974. 82 pp.

HUMANISTIC PERSPECTIVES IN MEDICAL ETHICS: Edited by Maurice B. Visscher. Prometheus Books, Buffalo, New York, 1972. 310 pp. $11.95.

MAN FOR MAN: A MULTIDISCIPLINARY WORKSHOP ON EFFECTING MAN'S SOCIAL AND PSYCHOLOGICAL NATURE THROUGH COMMUNITY ACTION: Edited by John L. Carleton and Ursula Mahlendorf. Charles C Thomas, Springfield, Illinois, 1973. 355 pp. $10.95.

THE ORIGINS OF LIFE: By Cyril Ponnamperuma. E. P. Dutton, New York, 1972. 215 pp. $7.95.

PARTNERWAHL UND EHE—THEORIE UND PRAXIS: Edited by Hans W. Jürgens. Wissenschaftlicher Verlag Altmann, Hamburg, Germany, 1972. 217 pp.     

High levels of expression of multiple enzymes in the Smirnoff-Wheeler pathway are important for high accumulation of ascorbic acid in acerola fruits

ABSTRACT

Acerola fruits contain abundant ascorbic acid (AsA). The gene expression levels of three upstream enzymes in the primary AsA biosynthesis pathway were correlated with AsA contents in the fruits of two acerola cultivars. Multiple overexpression of the enzymes increased AsA contents, suggesting their high expression is important for high AsA accumulation in acerola fruits and the breeding of AsA-rich plants.

Abbreviations: AsA: ascorbic acid; PMI: phosphomannose isomerase; PMM: phosphomannomutase; GMP: GDP-d-mannose pyrophosphorylase; GME: GDP-d-mannose 3?,5?-epimerase; GGP: GDP-l-galactose phosphorylase; GPP: l-galactose-1-phosphate phosphatase; GDH: l-galactose dehydrogenase; GLDH: l-galactono-1,4-lactone dehydrogenase     

Optimization of the 503 antigen induction strategy of Leishmania infantum chagasi expressed in Escherichia coli M15

Abstract

Leishmaniosis is a complex of diseases that can be fatal, if not given proper attention. Despite its relevance in the public health system, there is no vaccine capable of preventing the disease in humans so far and its treatment is expensive and aggressive to human health. The present study aims to optimize the induction parameters of the 503 Leishmania i. chagasi antigen expressed in recombinant Escherichia coli M15. The induction at different cell densities was evaluated in order to analyze the influence of the induction time on the yield of the protein of interest. In this segment, lactose and isopropyl-β-d-thiogalactopyranoside (IPTG) were used as inducer molecules, using various concentrations: 0.1?g/L, 1.0?g/L, and 10?g/L for lactose and 20?μM, 100?μM, 500?μM, and 1000?μM for IPTG. The results presented that the concentration of IPTG that obtained the higher antigen levels was that of 100?μM (0.087?g/L), a 10-fold lower concentration than was being previously used in this type of system and for lactose, it was 1?g/L (0.016?g/L). Thus, the induction with 100?μM allowed obtaining the antigen with a concentration 5.6 times higher than the lactose induction maximum concentration.     

Antitumor Activities and Immunochemical Properties of the Cell-wall Polysaccharides from Aureobasidium pullulans

Delipidated cell walls from Aureobasidium pullulans were fractionated systematically.

The cell surface heteropolysaccharide contains D-mannose, D-galactose, D-glucose, and D-glucuronic acid (ratio, 8.5:3.9:1.0:1.0). It consists of a backbone of (1→6)-α-linked D-mannose residues, some of which are substituted at O-3 with single or β-(1→6)-linked D-galactofuranosyl side chains, some terminated with a D-glucuronic acid residue, and also with single residues of D-glucopyranose, D-galactopyranose, and D-mannopyranose.

This glucurono-gluco-galactomannan interacted with antiserum against Elsinoe leucospila, which also reacted with its galactomannan, indicating that both polysaccharides contain a common epitope, i.e., at least terminal β-galactofuranosyl groups and also possibly internal β-(1→6)-linked galactofuranose residues.

It was further separated by DEAE-Sephacel column chromatography to gluco-galactomannan and glucurono-gluco-galactomannan.

The alkali-extracted β-D-glucan was purified by DEAE-cellulose chromatography to afford two antitumor-active (1→3)-β-D-glucans. One of the glucans (M_r, 1–2 × 10⁵) was a O-6-branched (1→3)-β-D-glucan with a single β-D-glucosyl residue, d.b., 1/7, and the other (M_r, 3.5–4.5 × 10⁵) had similar branched structure, but having d.b., 1/5. Side chains of both glucans contain small proportions of β-(1→6)-and β-(1→4)-D-glucosidic linkages.     

A New Synthesis of 9-(2-Deoxy-2-fluoro-β-D-arabinofuranosyl)guanine (araF-G)

Abstract

Interesting and very promising antisense properties of 2′-deoxy-2′-fluoroarabinonucleic acids ((a) Wilds, C.J.; Damha, M.J. 2′-Deoxy-2′-fluoroarabinonucleosides and oligonucleotides (2′F-ANA): synthesis and physicochemical studies. Nucl. Acids Res. 2000, 28, 3625–3635; (b) Viazovkina, E.; Mangos, M.; Elzagheid, M.I.; Damha, M.J. Current Protocols in Nucleic Acid Chemistry 2002, 4.15.1–4.15.21) (2′F-ANA) has encouraged our research group to optimize the synthetic procedures for 2′-deoxy-2′-fluoro-β-D-arabinonucleosides (araF-N). The synthesis of araF-U, araF-T, araF-A and araF-C is straightforward, (Tann, C.H.; Brodfuehrer, P.R.; Brundidge, S.P.; Sapino, C., Jr. Howell H.G. Fluorocarbohydrates in synthesis. An efficient synthesis of 1-(2-deoxy-2-fluoro-β-D-arabinofuranosyl)-5-iodouracil (β-FIAU) and 1-(2-deoxy-2-fluoro-β-D-arabinofuranosyl)thymine (β-FMAU). J. Org. Chem. 1985, 50, 3644–3647; Howell, H.G.; Brodfuehrer, P.R.; Brundidge, S.P.; Benigni, D.A.; Sapino, C., Jr. Antiviral nucleosides. A stereospecific, total synthesis of 2′-fluoro-2′-deoxy-β-D-arabinofuranosyl nucleosides. J. Org. Chem. 1988, 53, 85–88; Maruyama, T.; Takamatsu, S.; Kozai, S.; Satoh, Y.; Izana, K. Synthesis of 9-(2-deoxy-2-fluoro-β-D-arabinofuranosyl)adenine bearing a selectively removable protecting group. Chem. Pharm. Bull. 1999, 47, 966–970) however, the synthesis of the guanine analogue is more complicated and affords poor to moderate yields of araF-G (4) ((a) Elzagheid, M.I.; Viazovkina, E.; Masad, M.J. Synthesis of protected 2′-deoxy-2′-fluoro-β-D-arabinonucleosides. Synthesis of 2′-fluoroarabino nucleoside phosphoramidites and their use in the synthesis of 2′F-ANA. Current Protocols in Nucleic Acid Chemistry 2002, 1.7.1–1.7.19; (b) Tennila, T.; Azhayeva, E.; Vepsalainen, J.; Laatikainen, R.; Azhayev, A.; Mikhailopulo, I. Oligonucleotides containing 9-(2-deoxy-2-fluoro-β-D-arabinofuranosyl)-adenine and -guanine: synthesis, hybridization and antisense properties. Nucleosides, Nucleotides and Nucl. Acids 2000, 19, 1861–1884). Here we describe an efficient synthesis of araF-G (4) that involves coupling of 2-deoxy-2-fluoro-3,5-di-O-benzoyl-α-D- arabinofuranosyl bromide (1) with 2-chlorohypoxanthine (2) to afford 2-chloro-β-araF-I (3) in 52% yield. Nucleoside (3) was transformed into araF-G (4) by treatment with methanolic ammonia (150°C, 6 h) in 67% yield.     

Syntheses of Several β-l-Rhamnopyranosides

To investigate the substrate specificity of β-l-rhamnosidase, the following β-l-rhamnopyranosides were synthesized: 1-(β-l-rhamnopyranosyl)-dl-glycerol (1), methyl β-l-rhamnopyranoside (2), methyl 2-O-(β-l-rhamnopyranosyl)-β-d-glucopyranoside (3) and methyl 2-O-β(β-l-rhamnopyranosyl)-α-l-arabinopyranoside (4). The synthesis of 3 was performed using l-quinovose with neighboring group participation, which lead stereoselectively to the β-l-quinovoside. The 2-OH of the l-quinovo-unit was selectively deblocked, oxidized to the keto group, and then stereoselectively reduced, whereby 3 was produced.     

Production of Xylanase by Streptomyces sp., Using Non-metabolizable Inducer

meso-Diaminopimelate dehydrogenase (EC 1.4.1.16) was purified to homogeneity from Corynebacterium glutamicum ATCC 13032. The enzyme had a molecular weight of about 70,000 and consisted of two subunits identical in molecular weight. The enzyme was highly specific for meso-2,6-diaminopimelate. The pH optima for deamination and amination were about 9.8 and 7.9, respectively. The Michaelis constants were 3.1mm for meso-2,6-diaminopimelate, 0.12mm for NADP⁺, 0.28 mm for l-2-amino-6-ketopimelate, 36 mm for ammonia, and 0.13 mm for NADPH. d and l isomers of 2,6-diaminopimelate competitively inhibited the oxidative deamination of meso-2,6-diaminopimelate. The enzyme was distributed in a wider range of bacterial species than reported previously [Misono et al., J. Bacteriol., 137, 22 (1979)] when assayed by a sensitive formazan formation method.     

Effects of Acetylation with Acetic Anhydricle

1. L-Asparaginase (EC 3.5.1.1) from Escherichia coli A–l–3 was acetylated using acetic anhydride as a modifying chemical. The fully acetylated L-asparaginase retained 60% of the activity of the unmodified L-asparaginase.

2. The acetylated L-asparaginase hydrolyzed D-asparagine and L-glutamine as well as L-asparagine in the same ratio as the unmodified L-asparaginase did.

3. However, the effects of pH on the activity of the acetylated L-asparaginase showed very interesting differences from that of L-asparaginase. On the other hand, both L-asparaginase and the acetylated L-asparaginase exhibited similar pH activity curves on L-glutamine hydrolysis.

4. The acetylated L-asparaginase was found to become more stable against acid or heat in the presence of L-aspartate than in its absence in the same manner as L-asparaginase was.

     

Biochemical characteristics of maltose phosphorylase MalE from Bacillus sp. AHU2001 and chemoenzymatic synthesis of oligosaccharides by the enzyme

ABSTRACT

Maltose phosphorylase (MP), a glycoside hydrolase family 65 enzyme, reversibly phosphorolyzes maltose. In this study, we characterized Bacillus sp. AHU2001 MP (MalE) that was produced in Escherichia coli. The enzyme exhibited phosphorolytic activity to maltose, but not to other α-linked glucobioses and maltotriose. The optimum pH and temperature of MalE for maltose-phosphorolysis were 8.1 and 45°C, respectively. MalE was stable at a pH range of 4.5–10.4 and at ≤40°C. The phosphorolysis of maltose by MalE obeyed the sequential Bi–Bi mechanism. In reverse phosphorolysis, MalE utilized d-glucose, 1,5-anhydro-d-glucitol, methyl α-d-glucoside, 2-deoxy-d-glucose, d-mannose, d-glucosamine, N-acetyl-d-glucosamine, kojibiose, 3-deoxy-d-glucose, d-allose, 6-deoxy-d-glucose, d-xylose, d-lyxose, l-fucose, and l-sorbose as acceptors. The k_cat(app)/K_m(app) value for d-glucosamine and 6-deoxy-d-glucose was comparable to that for d-glucose, and that for other acceptors was 0.23–12% of that for d-glucose. MalE synthesized α-(1→3)-glucosides through reverse phosphorolysis with 2-deoxy-d-glucose and l-sorbose, and synthesized α-(1→4)-glucosides in the reaction with other tested acceptors.     

Branched Chain Amino Acid Aminotransferase of Pseudomonas sp

Branched chain amino acid aminotransferase was partially purified from Pseudomonas sp. by ammonium sulfate fractionation, aminohexyl-agarose and Bio-Gel A-0.5 m column chromatography.

This enzyme showed different substrate specificity from those of other origins, namely lower reactivity for l-isoleucine and higher reactivity for l-methionine.

Km values at pH 8.0 were calculated to be 0.3 mm for l-leucine, 0.3 mm for α-ketoglutarate, 1.1 mm for α-ketoisocaproate and 3.2 mm for l-glutamate.

This enzyme was activated with β-mercaptoethanol, and this activated enzyme had different kinetic properties from unactivated enzyme, namely, Km values at pH 8.0 were calculated to be 1.2 mm for l-leucine, 0.3 mm for α-ketoglutarate.

Isocaproic acid which is the substrate analog of l-leucine was competitive inhibitor for pyridoxal form of unactivated and activated enzymes, and inhibitor constants were estimated to be 6 mm and 14 mm, respectively.     

Sugli Effetti Provocati Dallo Scambio Degli Embrioni Fra Cariossidi Normali E Bianconate Del Grano “Cappelli”

Abstract

Effects induced by the exchange of embryos between normal grains and yellow-berries of « Cappelli » (Triticum durum Desf.). — Normal grains of « Cappelli » give seedlings, the shoots of which are longer than those coming from yellow-berries (Meletti e Onnis, 1961, a). The exchange of embryos between the two grain types shows the influence of endosperm on the seedling growth: the normal endosperm stimulates, while the yellow-berries endosperm depresses. The causes of this phenomenon are to research probably within the limits of the relationship, at biochemical level, between embryo end endosperm, with special regard to a likely different hormonic situation in normal grains and yellow-berries.     

2′-Fluoro-4′-thio-2′,3′-unsaturated Nucleosides: Anti-HIV Activity,Resistance Profile,and Molecular Modeling Studies

Abstract

Both D- and L-2′-fluoro-4′-thio-2′,3′-unsaturated nucleosides were synthesized and their anti-HIV activity against the drug sensitive virus and lamivudine-resistant mutant (M184V) were evaluated. In vitro antiviral evaluation indicated that the L-isomers are more potent than the D-isomers, but unfortunately all were cross-resistant with 3TC. Molecular modeling studies revealed that the unnatural sugar moiety of the L-nucleosides as well as 4′-sulfur atom of the D-isomer has a steric conflict with the bulky side chain of valine 184, resulting in cross-resistance.