- Volume 20, Issue 2, 1959
Volume 20, Issue 2, 1959
- Article
-
-
-
Cultivation of Mycobacteria Rocked in Non-Protein Medium Containing a High Concentration of Tween 80
More LessSUMMARY: Mycobacteria were grown in rocked ┴ tubes (Monod) in a medium which contained asparagine, glycerol, 1·0% (w/v) Tween 80 and no albumin fraction V. This permitted abundant well-dispeTsed diffuse growth. The amount of growth could be measured photometrically.
-
-
-
-
A Rapid Antibacterial Test for Mycobacteria Using a Reverse T Type of Tube in Rocked Culture
More LessSUMMARY: Antibacterial tests with mycobacteria were carried out in rocked JL tubes (Monod). The medium used was Sauton medium+1% (w/v) Tween 80. It took 48 hr. to get a reproducible value for the ID 50 dose (50% inhibition dose) with tubercle bacilli of human type, and 8 hr. with the avian type.
-
-
-
[14C] Glucose Metabolism in Fungal Cells
More LessSUMMARY: The incorporation pattern of 14C from [14C]glucose by the fungus Zygorhynchus moelleri has been investigated. The following substances became labelled in incubation periods of 6 sec. to 30 min.: the monophosphates of glucose, fructose, sedoheptulose, ribose, maltose, glycerol, gluconic acid, glyceric acid, enolpyruvic acid and guanosine; the diphosphates of fructose, glucose, glyceric acid, adenosine, uridine, inosine and guanosine; the triphosphates of adenosine and uridine; uridinediphosphoglucose and uridinediphosphoribose; free maltose and fructose; aspartic acid, glutamic acid, alanine, valine, tyrosine, proline, histidine, threonine, citrulline and glutamine; malic acid, citric acid, succinic acid, fumaric acid and glyceric acid. A small percentage of the 14C was present in unidentified substances. The kinetics of the incorporation of 14C, first into uridinediphosphoglucose, then into maltose phosphate, and finally into free maltose, suggests this sequence of compounds for the biosynthetic pathway of maltose formation.
The main effects of starvation of the cells by shaking them in phosphate buffer for 24 hr. were an increased % incorporation of 14C into maltose and the sugar phosphates, and a decreased % incorporation into amino acids, organic acids and nucleotides. The addition of a small amount of ammonia to starved cells increased the absolute rate of incorporation of 14C from labelled glucose into soluble cellular constituents; however, while the % of the total soluble 14C found in the nucleotides was markedly increased when ammonia was added, the % in the sugar phosphates decreased. In the presence of azide, the incorporation of 14C by starved cells into maltose and the nucleotides was severely inhibited and the incorporation into amino acids was somewhat increased. Thus, one of the most important results of starvation was to prevent incorporation of 14C into the nucleotides, organic acids and amino acids, while the addition of ammonia overcame the effects of starvation and promoted nucleotide synthesis. Ammonia had very little effect on the cells in the presence of azide.
A kinetic study of the sequence in which 14C was detected in these compounds indicated that glucose was metabolized by both the glycolysis and the oxidative pathways, and later by the tricarboxylic acid cycle.
-
-
-
Movement of Sodium and Cell Volume Changes in a Sodium-Rich Yeast
More LessSUMMARY: Sodium-rich yeast was prepared by aerating a yeast suspension in m-NaCl for a period of 60 min. This yeast contained then on the average 0·070–0·075 m- equiv. Na/g. dry wt. On incubating it with glucose, xylose or lactose in water, 0·1 m-KCI or 0·1 m-NaCl it lost some of its sodium, in the last case against an apparent concentration gradient. It appears that this movement of Na ion is of a diffusion character as evidenced by the effect of temperature, by incubation without metabolizable substrates and by the use of metabolic inhibitors; however, the possibility of an active contribution to this efflux cannot be excluded. The movement of Na+ out of the cell was shown to be connected with considerable changes of cell volume effected above all by changes of osmotic pressure of the medium, sodium being lost as a 0·06m-0·10m solution. A discussion of these phenomena is presented.
-
-
-
Apparent Self-Fertility in Neurospora crassa
More LessSUMMARY: Single ascospores which gave rise to temporarily self-fertile cultures were found in Neurospora crassa. Genetical and cytological evidence suggested that these ascospores were disomic for the chromosome containing the mating-type locus, the disomy having arisen following partial desynapsis at meiosis and unequal distribution of univalents. At some time after germination, the nuclei reverted to the haploid state. If the disomic ascospore had been heterozygous at the mating-type locus, two sorts of haploids might occur and fertility probably resulted from mating between these.
-
-
-
Selection for Adaptability to New Environments in Aspergillus glaucus
More LessSUMMARY: Colonies of Aspergillus glaucus arising from single asexual spores or hyphal tips of the same or different homokaryon clones often vary in their adaptability to new environments. This shows itself as differences in the percentage survival and mean lag period of inocula taken from colonies growing on a normal medium when transferred to one containing a poison such as mercuric chloride, or unfamiliar sugar sources, e.g. arabinose, galactose, lactose and xylose.
The differences in adaptability to these new media between homokaryon clones are characteristically nuclear in origin, while those between colonies of the same clone are characteristically cytoplasmic. The nuclear system might be formally regarded as epistatic to the cytoplasmic system involved in these adaptive changes.
Selection for the cytoplasmic differences can produce marked changes in the adaptability of the asexual spores of single colonies, even though the selection technique is such that colonies in the direct line of selected descent are at no time exposed to the new media.
The changes in adaptability to mercuric chloride are independent of those for adaptability to the new sugars and only the latter shows any correlation with changes in rate of growth. There is therefore evidence of two or possibly three cytoplasmic systems with much the same properties of variation but independent in action and transmission.
-
-
-
The Formation of Methionine by a Methionine-Requiring Mutant of Neurospora crassa
More LessSUMMARY: A methionine-requiring mutant of Neurospora crassa incorporated 35SO4 into methionine. This incorporation represents net synthesis of methionine by the mutant. It is quite likely that methionine synthesis proceeds by the normal pathway in the mutant. Not all of the normal proteins can be synthesized when methionine supplies are limiting, accounting for the inability of the mutant to begin growth without a long lag even though methionine can be synthesized.
-
-
-
Iron as a Growth Requirement for Pathogenic Leptospira
More LessSUMMARY: Virulent and avirulent strains of Leptospira icterohaemorrhagiae did not grow from inocula of fewer than 107 organisms/ml. in Korthof medium, but did grow when FeCl3 or preparations containing iron porphyrins were added. With added FeCl3 or haematin growth was somewhat slower than when the iron porphyrin-containing preparations were added.
-
-
-
A New Sulphate-Reducing Vibrio
More LessSUMMARY: An obligately anaerobic sulphate-reducing vibrio (NCIB 8382) isolated from soil from Singapore differs from known species of sulphate-reducing bacteria. The organism is relatively large, with one or two flagella, Gram-negative, lacks hydrogenase and pigments characteristic of Desulphovibrio desulphuricans, though an insoluble cytochrome is present. It grows with lactate or pyruvate, but is unable to metabolize acetate, propionate or butyrate; it reduces sulphate, sulphite or thiosulphate but not tetrathionate. Sporulation is rare but has been observed. The name Desulphovibrio orientis is proposed for this organism.
-
-
-
The Nature of the Capsular Polysaccharides of the Dextran-Producing Organisms Leuconostoc mesenteroides, L. dextranicum and Streptococcus bovis
More LessSUMMARY: The true capsular polysaccharide of Streptococcus bovis contains galactose, glucose, rhamnose and an uronic acid as constituent sugars, whereas those of Leuconostoc mesenteroides and L. dextranicum contain only galactose and glucose in about equal proportions. Contamination of the capsule with dextran, not easily removed by simple washing of the harvested organisms, may occur with all species when grown in sucrose or in glucose media. This contamination is minimized when a glucose medium is inoculated with a glucose culture many times removed from a sucrose-containing medium.
-
-
-
The Influence of Vitamin B12 on Growth Rate and Cell Composition of the Flagellate Ochromonas malhamensis
More LessSUMMARY: In cultures of the flagellate Ochromonas malhamensis the rate of growth is determined by the concentration of cyanocobalamin up to a limit at which a maximum growth rate is achieved. In organisms grown exponentially with different rate-limiting concentrations of cyanocobalamin, the amounts of protein and nucleic acids were approximately proportional to the rates at which the organisms had grown. With increasing growth rate the concentrations of riboflavin, nicotinic acid, pantothenic acid and chlorophylls increased. Carbohydrate showed little change, whereas fat and ‘free’ amino-nitrogen diminished in concentration as the growth rate increased. In cultures of O. malhamensis grown with limiting or near-limiting concentrations of cyanocobalamin and with increasing concentrations of chloramphenicol, the rates of division declined asymptotically to a low value corresponding with 500 μg. chloramphenicol/ml. culture medium. Inhibition of growth caused by the antibiotic was annulled by increasing the concentration of cyanocobalamin in the culture medium.
-
-
-
The Adansonian Classification of the Staphylococci
More LessSUMMARY: The Adansonian method of classification, in which all features are given equal weight in deducing similarity between strains, has been applied to staphylococci. Staphylococcus aureus, S. saprophyticus and S. roseus are natural groups, but S. lactis and S. afermentans are not, for individual strains of these ‘ species ’ are as different from each other as from the three previous species. The group as a whole is divided into two main branches which might be regarded conveniently as two genera, Staphylococcus and Micrococcus.
-
-
-
The Use of Models in Bacterial Classification
More LessSUMMARY: The making of models for taxonomic purposes and their use is described, and the fidelity with which they can represent the taxonomic relations between bacteria is discussed. These models are particularly useful for teaching purposes.
-
-
-
The Fixation of Tetanus Toxin by Nervous Tissue
More LessSUMMARY: The fixation of tetanus toxin by nervous tissue (Wassermann-Takaki phenomenon, 1898) has been re-investigated. Fixation is greatly dependent on the concentration of toxin and of receptor. Toxin is fixed in preference to toxoid, but its toxicity does not appear to be markedly diminished by fixation. A biological assay of the toxin receptor in nervous tissue and its components has been devised. The receptor activity is not due to a cerebroside, as thought by Landsteiner & Botteri (1906), but to some substance (present mainly in grey matter) that tends to associate with it.
-
-
-
Chemical Assay of the Tetanus Toxin Receptor in Nervous Tissue
More LessSUMMARY: The fixation of tetanus toxin by the receptor in nervous tissue is highly specific in so far as tetanus toxic protein (and toxoid to a much smaller extent), and apparently nothing else, is adsorbed from solutions of ionic strength greater than 0·15. At lower ionic strengths certain other proteins may be adsorbed by a mechanism that is probably different. The specific adsorption of toxic protein has been used as the basis of a chemical method of assay of the receptor which depends on the estimation of the amount of protein adsorbed under prescribed conditions by the unknown amount of receptor from a fixed amount of crude tetanus toxin.
-
-
-
Tentative Identification of the Tetanus Toxin Receptor in Nervous Tissue
More LessSUMMARY: The tetanus toxin receptor in nervous tissue appears to be a ganglioside (mucolipid, strandin, containing: fatty acid, sphingosine, glucose, galactose, acetylgalactosamine, acetylneuraminic acid and amino acid (?) residues). The water- soluble ganglioside occurs in nervous tissue in the form of labile water-insoluble complexes with cerebrosides and sphingomyelins. The solubility of the complexes in water increases with increasing ganglioside content, but decreases when calcium is incorporated. Standing with ganglioside inactivates the toxin.
-
-
-
Osmotic Properties of Protoplasts of Micrococcus lysodeikticus
A. R. Gilby and A. V. FewSUMMARY: Protoplasts were released from Micrococcus lysodeikticus by the action of lysozyme in media containing sucrose, NaCl or mixtures of these. Empirical corrections by two methods were made for the effect of refractive index on the optical density of the protoplast suspensions measured at 500 mμ. With the assumption, valid for some similar systems, that the optical density of a protoplast suspension is inversely proportional to the protoplast volume, the protoplasts were shown to behave as osmometers at osmotic pressures above the threshold for lysis and to follow a van’t Hoff-Boyle law. The osmotically-inactive volume in a standard stabilizing medium containing m-sucrose + 0·05m-NaCl (osmotic pressure 37·8 atm.) was c. 76 %. Protoplasts formed in hypotonic media were more resistant to osmotic explosion than those formed at higher medium concentrations and subsequently diluted.
-
-
-
Experiments on Splash Dispersal of Fungus Spores
More LessSUMMARY: Splash dispersal (first studied by Faulwetter, 1917a, b) is characteristic of many bacterial plant pathogens and slime-spored fungi. The mechanism of splash has been studied in the laboratory under simplified conditions with water drops falling from known heights on to thin films of a suspension of conidia of Fusarium solani spread on horizontal glass surfaces. The resulting splash droplets were caught, counted and measured by the naphthol green B slide method (Liddell & Wootten, 1957). Both the total number of droplets produced and of those carrying spores increased as the film thickness decreased, and as the size and velocity of the incident drop increased.
One incident drop 5 mm. in diameter falling on a horizontal film of spore suspension 0·1 mm. thick on a glass surface produced over 5200 splash droplets of which over 2000 carried one or more spores. The sizes of splash droplets ranged from 5μ about 2400μ, and their size distribution was of the log probability type. The median diameter was 70μ for all droplets, and 140 μ for droplets carrying spores. The medium horizontal distances travelled by these droplets in still air was 10 and 20 cm. respectively. Increasing the film thickness to 0·5 and 1·0 mm. reduced the total resulting droplets to 3500 and 2100 (1600 and 500 carrying spores), respectively. Neither median diameter nor median distance of horizontal travel were much altered by varying the diameter of incident drop or film thickness. Droplets of diameters between 164 and 655μ tended to travel further than either smaller or larger droplets. Small spores such as those of Gloeosporium album, Colletotrichum lindemuthianum and Nectria cinnabarina were even more readily picked up from suspension than the macroconidia of Fusarium solani.
The number of droplets deposited per unit area on a horizontal plane decreased rapidly with increasing distance from point of impact, and in still air few droplets travelled beyond 70 cm.
Splash on a twig bearing conidial fructifications of Nectria cinnabarina produced 2000 spore-carrying droplets, and the sequence of events is shown by high-speed photography.
A splash droplet consists of an intimate mixture of liquid from both the incident drop and the surface film. The larger splash droplets contain spores if either the incident drop or the surface film is a spore suspension. Both raindrops falling at terminal velocity and drops falling more slowly from vegetation may operate the splash dispersal mechanism. Splash in rain or drip from trees may act as a complete dispersal mechanism in still air, or as a ‘take-off’ mechanism leading to dispersal by wind. Both functions are important in plant epidemiology.
-
-
-
The Origin of Bacterial Resistance to Proflavine
More LessSUMMARY: Several strains from Escherichia coli NCTC 8196 were isolated from discrete colonies. They were grown in liquid media in the presence of proflavine, and then in its absence. The distribution of resistance was measured by the number of organisms able to multiply at different concentrations of proflavine. Some strains were also grown in the presence of proflavine on plates, and the resistance of broth cultures from them was measured on gradient plates. The results cannot be explained on the assumption that the resistance was determined solely by specifically induced adaptation.
-
-
-
The Origin of Bacterial Resistance to Proflavine
More LessSUMMARY: Experiments were performed to demonstrate the production in Escherichia coli of spontaneously occurring mutants resistant to proflavine. The fluctuation test of Luria & Delbriick (1943) suggested that such mutants arise. This was confirmed by a modification of the technique of Lederberg & Lederberg (1952). By this method of indirect selection by replica plating, two separate first- step mutants were isolated; from one of these was isolated a second-step mutant, and from this a third-step mutant. The resistance of the third-step mutant was about 100 times greater than that of the original sensitive strain. By the same technique, two first-step mutants to chloramphenicol resistance were isolated. None of the 6 mutants had come into contact with either drug until the time of testing. Crossresistance between proflavine and chloramphenicol was shown by 5 of the 6 mutants; the sixth showed an increase in proflavine resistance though not in resistance to chloramphenicol.
-
-
-
The Origin of Bacterial Resistance to Proflavine
More LessSUMMARY: It was reported (Baskett, 1952) that small additions of proflavine made at intervals to a growing culture of Bacterium lactis aerogenes (synonyms Aerobacter aerogenes, Klebsiella pneumoniae), did not prevent continued growth; this was regarded as proof that drug resistance might be acquired by adaptation. This phenomenon does not occur with Escherichia coli grown in broth, but we confirm that it occurs with B. lactis aerogenes grown in a chemically defined medium containing glucose. Growth of the aerogenes organism ceased when all the proflavine was added at once. Examination of the aerogenes organisms at the end of the experiments showed that a high proportion had become slightly more resistant, and a few had become highly resistant. These changes were not sufficient to account for continued growth of the aerogenes organisms in increasing concentrations of proflavine. In high concentrations of proflavine, growth of sensitive organisms did occur when some filtrate from a drug-free culture was added to the culture medium. It also occurred when the growing culture was kept acid, or when the medium was made acid before inoculation. On the other hand, growth did not occur in the presence of proflavine when the culture was kept neutral. It is concluded that the growth of B. lads aerogenes in cultures to which proflavine is added gradually is chiefly due to a decrease of the inhibitory action of the drug by the acid formed during growth in a glucose + salts medium. The absence of the phenomenon when E. coli was grown in broth can be explained by the absence of glucose so that there was no lowering of pH value. There is thus no evidence of a rapid adaptation to proflavine resistance in B. lactis aerogenes.
-
-
-
The Origin of Bacterial Resistance to Proflavine
More LessSUMMARY: Small amounts of proflavine were added at intervals of 30 min. to growing cultures of Escherichia coli. Additions during the logarithmic phase gave an increase of resistance of two- or threefold in a high proportion of organisms. Additions in the lag or late logarithmic phase gave no such increase, although the resistance of the organisms themselves was higher in these phases. Whether organisms were able to grow in the presence of proflavine, therefore, depended not only on their resistance but on the conditions in the culture medium. The increase in proflavine resistance, which occurred when drug was added to growing cultures, was not accompanied by increase of cross-resistance to other drugs. The resistance was lost on growth in the absence of drug. For these reasons, the increase is held to be a phenotypic adaptation. There was also an increase in the number of organisms with a high resistance, of the order of that of mutants. These organisms showed cross resistance with other drugs.
Partial synchronization of division was achieved by the temporary cooling of cultures. These synchronized cultures showed cycles of division of about 30 min. They also showed cycles of resistance of c. 20 min. Evidence is presented for the view that the organisms undergo cycles of varying adaptability to proflavine resistance. It is suggested that this variation in adaptability can explain the range of resistance found in an ordinary sensitive culture. It can also explain the effect of proflavine additions in raising the resistance of a high proportion of organisms in a growing culture.
-
-
-
The Origin of Bacterial Resistance to Proflavine
More LessSUMMARY: We attempted to transform proflavine-sensitive strains of Escherichia coli to proflavine resistance by growth in the presence of deoxyribonucleic acid-containing extracts from resistant organisms. Three methods were used to obtain the DNA preparations. Method 1 (Boivin, 1947) did not give active transforming principle, even when a variety of modifications was introduced. Method 2 (McCarty & Avery, 1946) and Method 3 (Mayers & Spizizen, 1954) gave extracts which were active in transformation. With DNA prepared by Method 2, an increase in the number of resistant organisms was found in one of four rough sensitive strains. We concluded that only a small proportion of the organisms of this strain were competent. We were able to increase the proportion of these competent organisms by a method of ‘double replica plating’. According to Method 3, organisms were lysed by sodium dodecylsulphate (Duponol) in presence of citrate, and protein removed by sodium acetate. From the supernatant fluid transforming principle was precipitated by acidified ethanol, and then dissolved in saline. The smooth strain of Escherichia coli used in most of our experiments served as the recipient strain. The transforming principle from resistant organisms was not active alone, but was active in the presence of the protein precipitate. The activity appeared to be lost when the transforming principle was treated with DNAase. No activity was shown by extracts from sensitive organisms. The activation of transforming principle by the protein precipitate is thought to be due to the Duponol carried with it. Duponol appears to inhibit DNAase, so that it might act by preserving transforming DNA from destruction by the enzyme present in the recipient organisms. Our experiments did not always give positive results. Whilst we believe that we have demonstrated transformation in this system, the low reproducibility of our results makes it necessary to repeat and extend.
-
-
-
The Serology and Pathogenicity of the Genus Chromobacterium
More LessSUMMARY: Mesophilic strains of the genus Chromobacterium were found to cross-agglutinate extensively, and much of this appears to be due to common rough somatic antigens. The psychrophilic strains also cross-agglutinated to some extent. There was little cross-agglutination between mesophils and psychrophils. Neither mesophils nor psychrophils showed clear-cut antigenic subgroups. Many mesophilic strains, whether isolated from naturally-occurring cases of infection or from water, were found to be virulent for experimental animals. The most virulent were strains from two cases of human infection, which had an LD50 dose for guinea-pigs of c. 5 × 106 viable organisms. The virulent strains did not form a homogeneous antigenic group. Cultures of mesophils contained an endotoxin, but no exotoxin was found. The experimental disease may be an acute, rapidly fatal septicaemia, or a more chronic disease with multiple abscess formation like that found in natural infections; occasionally a local abscess with subsequent recovery was the only result of the injection of cultures.
-
-
-
Changes in Serological Type and Antibiotic Resistance of Lancefield Group D Streptococci in Chickens Receiving Dietary Chlortetracycline
More LessSUMMARY: The effect of dietary chlortetracycline on the serological type and resistance of the streptococci found in the caeca of chickens has been investigated. In the control birds where only chlortetracycline-sensitive streptococci were present initially, Streptococcus faecium predominated and S. faecalis (mainly the proteolytic variant) was present in small numbers representing three serological types (types H 69 D5, D15 and D76). Administration of chlortetracycline, whether at a low concentration throughout life or intermittently at a high concentration, led to the emergence of a highly-resistant non-proteolytic strain of S. faecalis (type H 69 D5) which became predominant in the antibiotic treated birds. Withdrawal of chlortetracycline was followed by disappearance of type H 69 D5 and the reappearance of types D15 and D76 which were proteolytic. Type D15 remained sensitive to chlortetracycline, but type D76 had become more resistant and eventually became the predominant streptococcus in all the chickens under observation. The serological types of S. faecalis identified in these chickens are also commonly found in the human intestine.
-
-
-
Permeability of the Envelopes of Staphylococcus aureus to some Salts, Amino Acids, and Non-Electrolytes
More LessSUMMARY: The passive permeability properties of the plasma-membrane of Staphylococcus aureus (strain Duncan) resemble those of a classical lipid membrane such as that considered by Overton in 1899. In general, solutes carrying more than four water molecules flow across the plasma-membrane only very slowly under an electrochemical gradient. The plasma-membrane is the effective osmotic barrier to small molecular weight solutes and prevents the escape of internal components having a total osmotic concentration corresponding to c. 1 molal sucrose. The protoplast is prevented from swelling by the cell wall which withstands a hydrostatic thrust of some 20 to 30 atmospheres pressure exerted against it by the plasma-membrane in distilled water. The pores in the cell wall, although large enough to permit rapid diffusion of small molecular weight solutes, are too small to allow a dextran of mol. wt. 10,000 to penetrate. The cell wall acts as the osmotic barrier for large molecular weight components, preventing such components in the medium from gaining access to the plasma-membrane surface and preventing such internal components from passing outwards from the surface of the plasma-membrane.
-
-
-
Heterokaryotic Compatibility in Streptomyces
More LessSUMMARY: The compatibility system in Streptomyces fradiae may be characterized as follows. When 108 conidia of each of two freshly isolated auxotrophic mutants are mated on minimal medium, a small number, usually 1 to 10, of ‘primary’ heterokaryotic colonies appear (low-frequency mating, LFM). On the other hand, when ‘secondary parental isolates’ (derived from the conidia produced by ‘primary’ heterokaryons) are mated, the frequency of heterokaryon formation is increased by a factor of several thousand. This high-frequency mating (HFM) is a reasonably stable property, decreasing (or increasing) in a stochastic manner, only after a considerable number of subcultures. A mutational origin is therefore postulated for the HFM and LFM isolates, which must be endowed with variable cultural fitness causing diverse population shifts upon subculture. More effective anastomosis, not increase in residual growth of the ‘secondary parental isolates’, appears to be responsible for HFM. No interspecific crosses were successful, even when an HFM tester stock was used, but heterokaryotic interaction between independently isolated auxotrophic mutants derived from the same line of S. fradiae seemed to increase when an HFM strain was one of the partners.
-
Volumes and issues
-
Volume 170 (2024)
-
Volume 169 (2023)
-
Volume 168 (2022)
-
Volume 167 (2021)
-
Volume 166 (2020)
-
Volume 165 (2019)
-
Volume 164 (2018)
-
Volume 163 (2017)
-
Volume 162 (2016)
-
Volume 161 (2015)
-
Volume 160 (2014)
-
Volume 159 (2013)
-
Volume 158 (2012)
-
Volume 157 (2011)
-
Volume 156 (2010)
-
Volume 155 (2009)
-
Volume 154 (2008)
-
Volume 153 (2007)
-
Volume 152 (2006)
-
Volume 151 (2005)
-
Volume 150 (2004)
-
Volume 149 (2003)
-
Volume 148 (2002)
-
Volume 147 (2001)
-
Volume 146 (2000)
-
Volume 145 (1999)
-
Volume 144 (1998)
-
Volume 143 (1997)
-
Volume 142 (1996)
-
Volume 141 (1995)
-
Volume 140 (1994)
-
Volume 139 (1993)
-
Volume 138 (1992)
-
Volume 137 (1991)
-
Volume 136 (1990)
-
Volume 135 (1989)
-
Volume 134 (1988)
-
Volume 133 (1987)
-
Volume 132 (1986)
-
Volume 131 (1985)
-
Volume 130 (1984)
-
Volume 129 (1983)
-
Volume 128 (1982)
-
Volume 127 (1981)
-
Volume 126 (1981)
-
Volume 125 (1981)
-
Volume 124 (1981)
-
Volume 123 (1981)
-
Volume 122 (1981)
-
Volume 121 (1980)
-
Volume 120 (1980)
-
Volume 119 (1980)
-
Volume 118 (1980)
-
Volume 117 (1980)
-
Volume 116 (1980)
-
Volume 115 (1979)
-
Volume 114 (1979)
-
Volume 113 (1979)
-
Volume 112 (1979)
-
Volume 111 (1979)
-
Volume 110 (1979)
-
Volume 109 (1978)
-
Volume 108 (1978)
-
Volume 107 (1978)
-
Volume 106 (1978)
-
Volume 105 (1978)
-
Volume 104 (1978)
-
Volume 103 (1977)
-
Volume 102 (1977)
-
Volume 101 (1977)
-
Volume 100 (1977)
-
Volume 99 (1977)
-
Volume 98 (1977)
-
Volume 97 (1976)
-
Volume 96 (1976)
-
Volume 95 (1976)
-
Volume 94 (1976)
-
Volume 93 (1976)
-
Volume 92 (1976)
-
Volume 91 (1975)
-
Volume 90 (1975)
-
Volume 89 (1975)
-
Volume 88 (1975)
-
Volume 87 (1975)
-
Volume 86 (1975)
-
Volume 85 (1974)
-
Volume 84 (1974)
-
Volume 83 (1974)
-
Volume 82 (1974)
-
Volume 81 (1974)
-
Volume 80 (1974)
-
Volume 79 (1973)
-
Volume 78 (1973)
-
Volume 77 (1973)
-
Volume 76 (1973)
-
Volume 75 (1973)
-
Volume 74 (1973)
-
Volume 73 (1972)
-
Volume 72 (1972)
-
Volume 71 (1972)
-
Volume 70 (1972)
-
Volume 69 (1971)
-
Volume 68 (1971)
-
Volume 67 (1971)
-
Volume 66 (1971)
-
Volume 65 (1971)
-
Volume 64 (1970)
-
Volume 63 (1970)
-
Volume 62 (1970)
-
Volume 61 (1970)
-
Volume 60 (1970)
-
Volume 59 (1969)
-
Volume 58 (1969)
-
Volume 57 (1969)
-
Volume 56 (1969)
-
Volume 55 (1969)
-
Volume 54 (1968)
-
Volume 53 (1968)
-
Volume 52 (1968)
-
Volume 51 (1968)
-
Volume 50 (1968)
-
Volume 49 (1967)
-
Volume 48 (1967)
-
Volume 47 (1967)
-
Volume 46 (1967)
-
Volume 45 (1966)
-
Volume 44 (1966)
-
Volume 43 (1966)
-
Volume 42 (1966)
-
Volume 41 (1965)
-
Volume 40 (1965)
-
Volume 39 (1965)
-
Volume 38 (1965)
-
Volume 37 (1964)
-
Volume 36 (1964)
-
Volume 35 (1964)
-
Volume 34 (1964)
-
Volume 33 (1963)
-
Volume 32 (1963)
-
Volume 31 (1963)
-
Volume 30 (1963)
-
Volume 29 (1962)
-
Volume 28 (1962)
-
Volume 27 (1962)
-
Volume 26 (1961)
-
Volume 25 (1961)
-
Volume 24 (1961)
-
Volume 23 (1960)
-
Volume 22 (1960)
-
Volume 21 (1959)
-
Volume 20 (1959)
-
Volume 19 (1958)
-
Volume 18 (1958)
-
Volume 17 (1957)
-
Volume 16 (1957)
-
Volume 15 (1956)
-
Volume 14 (1956)
-
Volume 13 (1955)
-
Volume 12 (1955)
-
Volume 11 (1954)
-
Volume 10 (1954)
-
Volume 9 (1953)
-
Volume 8 (1953)
-
Volume 7 (1952)
-
Volume 6 (1952)
-
Volume 5 (1951)
-
Volume 4 (1950)
-
Volume 3 (1949)
-
Volume 2 (1948)
-
Volume 1 (1947)