摘要:

When slices of potato tissue are stored for two days at 23 °C. in moist chambers or in aerated distilled water, the vitamin C content increases 100-300% as measured by the method of Roeet al. The increase does not occur in slices from freshly harvested potatoes. The physiological condition of the potatoes at the time of the experiment is important in determining the amount of increase in slices from potatoes stored for several months. Experiments with auxins and mannitol solutions show that there is no direct relationship between the process of water uptake and vitamin C formation. Solutions of indoleacetic acid and naphthaleneacetic acid increase the amount of vitamin formed. The results of experiments with potassium cyanide, sodium azide, malachite green, 8-hydroxyquinoline, sodium diethyldithiocarbamate and 2,4-dinitrophenol suggest that the formation of vitamin C is not directly related to any of the enzyme systems inhibited by the above chemicals. Infiltration of potato slices with solutions of fumaric and malic acid results in an increased formation of vitamin C as compared with the water controls.

ISSN:0008-4026    

DOI:10.1139/b52-044

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

Laurylamine saccharinate has been tested for its bacteriostatic powers against 30 species of bacteria, namely, 6 Gram-positive micrococci, 12 Gram-positive and 12 Gram-negative 'rods'. The compound was used in concentrations of 0.0005, 0.001, and 0.005% in plain broth, broth with glycerol, and broth with glycerol and skim milk, these adjuncts representing progressively increasing amounts of organic matter. The Gram-negative bacteria were the most resistant. The bacteriostatic action of the laurylamine was progressively reduced by the organic matter.Staphylococcus aureuswas not killed by 0.005% laurylamine in the medium containing skim milk. Media containing phenol were used as a measure of comparison, and similar effects of organic matter were observed. Agar also reduced the bacteriostatic power of the laurylamine.

ISSN:0008-4026    

DOI:10.1139/b52-045

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

One hundred and twenty-eight species of 44 genera of the family Compositae were examined as to their susceptibility to the dodder,Cuscuta europea. The indices presented are thus to supply additional data about host preference in the genusCuscuta.

ISSN:0008-4026    

DOI:10.1139/b52-046

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

A protease concentrate was obtained from the culture medium ofMortierella renisporaDixon-Stewart (PRL 26) by repeated precipitation with ammonium sulphate. The specific activity of the mold protease compared favorably with that of crystalline trypsin. The pH optimum was broad, with a maximum at a pH of 7.5 when hemoglobin was used as the substrate. A study of the pH stability characteristics showed that it was stable over a wide range (4.9 to 9.5) at 1 °C. and 25 °C. Ferrous ions caused a considerable increase in the activity of the enzyme preparations, other metals were ineffective as activators.

ISSN:0008-4026    

DOI:10.1139/b52-047

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

Under the experimental conditions used, amino acids played a very important part in the growth initiation of washed cells of alfalfa – sweet clover rhizobia. There were, however, distinct differences in utilization, both among genetically related mutants, and among other cultures when compared before and after plant passage. None of 15 vitamins, purines, and pyrimidines was able to initiate growth and hence these rhizobia are able to synthesize these compounds when a readily utilizable nitrogen source is present. Because of this fact, the stimulation of these bacteria by yeast extract is probably due, primarily, to the amino acid content. No strain was found able to concentrate free amino acids intracellularly or, when grown in lysine or tyrosine media, to excrete additional amino acids. No differences were found among effective, ineffective, or parasitic rhizobia in biochemical requirements.

ISSN:0008-4026    

DOI:10.1139/b52-048

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

A species ofAphanomyceswas isolated from damped-off pepper seedlings which had been grown in a sandy loam compost soil under glass. This fungus was obtained from up to 8% of the damped-off pepper seedlings. The morphological characteristics of this fungus corresponded so closely with the descriptions ofAphanomyces cladogamusDrech., which Drechsler isolated from diseased tomato rootlets, that the two fungi are considered to be the same. Reduction in stands of pepper seedlings resulted from both pre-emergence and post-emergence damping-off, when seeds were planted in soil inoculated with isolates of the fungus. Characteristic symptoms of postemergence attacks consisted of black lesions on the hypocotyl frequently extending into the bases of the cotyledons, and death of affected seedlings usually occurred.A.cladogamuswas found to cause a considerable amount of damping-off in tomato, eggplant, radish, and spinach as well as in pepper. It attacked Spanish onions only slightly, but lettuce, pea, and muskmelon not at all. Except in spinach,A.cladogamusshowed little tendency to colonize root tissues, whereas hypocotyl and cotyledonary tissues were highly vulnerable.

ISSN:0008-4026    

DOI:10.1139/b52-049

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

Decay ofPopulus tremuloidesMichx. andP.grandidentalaMichx. caused byFomes igniariusvar.populinus(Neuman) Campbell was studied at the Petawawa Forest Experiment Station, Ont., in stands up to 70 years of age. In eightacre sample plots representing stands 60 to 70 years old, 28.6 to 69.2% of the trees were infected; the percentage of decay in the gross merchantable cubic volume was 3.2 to 14.3 in the decayed trees, and 0.9 to 8.1 in decayed and sound trees considered together. Equally variable results were obtained in younger age classes. No relation between decay and site could be established on the basis of actual cubic volume, but when the trees were measured in board feet a slightly higher percentage of cull occurred on the poorer sites, owing at least partly to the smaller trees. Net periodic increment continued to increase in the 60–70-year age class on favorable sites. Sporophore-bearing trees died in the second and third years after being girdled, and the original number of mature living sporophores was reduced to 13% six years after girdling. On similar trees which were felled and left intact on the ground during the same period the number of sporophores increased. Artificial inoculations in both sapwood and heartwood of living trees resulted in the development of typical decay from which the pathogen was re-isolated. Observations on 5 to 18 sporophores from May 4 to June 30 of the following year proved that sporulation ofF.igniariusis continuous from early spring to late autumn. There is not necessarily any period of inactivity during which new tube layers are formed, though irregular periods of one to several days without sporulation are common. Sporulation is favored by high relative humidity and high temperature. The lowest temperature at which sporulation was observed was 40° F.

ISSN:0008-4026    

DOI:10.1139/b52-050

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

Plants of the White Rose and Netted Gem potato varieties naturally or artificially inoculated with the witches'-broom of potato virus expressed symptoms only after the progeny of inoculated plants was grown, but symptoms occurred on the foliage of the X virus-immune potato seedling 41956 within eight weeks after grafting. Tomato and tree tomato served as indicator plants on which two apparent strains of the virus could be distinguished. The first strain caused the symptoms on tomato usually associated with the disease on this suscept, but the second strain causedadisease similar to tomato big bud. Attempts to transmit the virus by means of dodder and insects were unsuccessful. An abrupt cessation of cambial activity and consequent underdevelopment of secondary conductive tissue precede the appearance of disease symptoms on potato.

ISSN:0008-4026    

DOI:10.1139/b52-051

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

The effectiveness of absorbed radiophosphorus for mutation induction in wheat and barley has been studied. The P32was supplied to seedlings and to young plants. Chromosome aberrations found in groups of several cells at meiosis were counted but single cell aberrations were not. Following some dosages of P32, as many as one-third of the treated plants were found to have blocks or clusters of aberrant cells. Samples of R2(progeny of treated) plants of vulgare wheat and of common barley were also examined for the presence of chromosome aberrations at meiosis. The samples consisted of 143 wheat and 128 barley plants. Approximately 8 to 19% of wheat and 6 to 11% of barley plants of different treatment groups had aberrations. Phenotypic mutants were found in barley, einkorn, and vulgare wheat. Chlorophyll mutants occurred in all of these though no albinos were produced invulgare. The R2and R3ofvulgare, consisting of 10,443 plants from 258 treated R1plants, included 15 recognized mutants. The original mutants did not breed true. Offspring of some mutants included only mutant and normal-appearing plants. Other mutants gave a variety of new phenotypic forms; some of these are true-breeding. Nearly all of the wheat mutants gave evidence of chromosome aberrations. Most of the phenotypic changes are therefore attributed to changed gene balance rather than to gene mutation.A few mutations have also been obtained by irradiating wheat and barley seeds with high-energy X rays from the betatron. Two such mutants in wheat were found to have undergone chromosome breakage and rearrangement.

ISSN:0008-4026    

DOI:10.1139/b52-052

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

A study of the distribution of glutamic carboxylase within the developing wheat plant revealed that it was absent in young plants, and was present only in traces in mature roots, and that it accumulated in mature leaves. Glutamic carboxylase was particularly abundant in the mature and senescent third leaf. Extracts of leaves of other cereals showed only weak activity, while extracts of roots, other than barley, were inactive. The high enzyme activity of the barley root extracts was exceeded only by that of mature wheat leaf extracts. A convenient method is described for enzyme storage at −40 °C. and a purification procedure was developed which effected a 500-fold concentration (nitrogen basis). The glutamic carboxylase activity of crude extracts was enhanced by preparatory exposure to phosphate buffer; after selective salt precipitation and lengthy dialysis, activity was reduced, but could be restored by the addition of pyridoxal phosphate. A heat-stable inhibitor of glutamic carboxylase at its pH optimum was found in the ether-soluble organic acid fraction of the cell sap ofKalanchoeleaves. Similar inhibiting effects were shown by malate, tartrate, and citrate, but not by succinate, fumarate, aspartate, and alanine. Kinetic studies indicated that the inhibition of plant glutamic carboxylase by cyanide is noncompetitive.

ISSN:0008-4026    

DOI:10.1139/b52-053

出版商:NRC Research Press    

年代:1952

数据来源: NRC