摘要:

The development of a nuclear polyhedrosis virus of the eastern hemlock looper,Lambdina fiscellaria fiscellaria, is described in gut and hypodermal tissues. Infection was found in the midgut cells where a cycle of virus replication occurred but no polyhedron formation was observed. In the hypodermis the mode of viral development was similar to that recorded for other nuclear polyhedroses which have bundles of virions surrounded by membranes and occluded in polyhedra. At an advanced stage of infection, non-occluded virions formed regular arrays in some of the infected nuclei. Other non-occluded virions were found in the cytoplasm and in large numbers near the periphery of cells. Angular cytoplasmic inclusion bodies showing the structure of polyhedron protein, but containing no virions, were associated with virus-infected cells in both the tissues examined.

ISSN:0008-4166    

DOI:10.1139/m71-011

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The phosphorylated pathway was established as a biosynthetic route toL-serine inMicrococcus lysodeikticus. Evidence was based upon the demonstration of the synthesis ofL-phosphoserine (PS) and serine fromD-3-phosphoglyceric acid (PGA) and by the detection of phosphoglyceric acid dehydrogenase and PS phosphatase activities in crude cell-free extracts. The synthesis of PS from PGA was enhanced byL-glutamic acid and byL-lactic dehydrogenase. PS phosphatase was stimulated by added Mg2+ion. The isolation of ser/gly−auxotrophs lacking PS phosphatase or the ability to synthesize PS from PGA confirmed the obligatory role of the phosphorylated pathway in serine biosynthesis in the organism.

ISSN:0008-4166    

DOI:10.1139/m71-012

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Hyphae ofVerticillium dahliaeKleb. penetrated cellophane membranes supported on a sucrose-rich medium. Vesicular production be penetrating hyphae was thought to be concerned with cell wall synthesis and the production of extramycelial enzymes which facilitated colonization. After complete dissolution of the membrane hyphae underwent a process of degeneration.

ISSN:0008-4166    

DOI:10.1139/m71-013

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Cochliodinol at 15 μg/ml reduced the respiration rate of microspores ofFusarium oxysporum, with glucose or succinate as substrate, by about 70%, and also inhibited their germination. The inhibitory effect was partially reversed by the addition of magnesium ions to the medium.

ISSN:0008-4166    

DOI:10.1139/m71-014

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

An atypical viability response to 5-bromouracil has been observed in a thymine auxotroph ofE.coliK-12. The response occurs in two phases, the first reflecting tolerance to the analogue during continued exponential growth and cell division. The second is a static phase during which viable number remains constant, while cell number and mass increase at a diminishing rate.During the latter phase filamentous cells increase in number and length. Examination of the cloning potential of cells after 10 h of growth in 5-bromouracil indicated that filamentous cells continue extension on solid medium into non-septate coils that are sterile. Other cells, presumably static when plated, readily form microcolonies free of defective members.Observed responses to penicillin, potentially stabilizing media, or added thymine suggest that 5-bromouracil evokes a bimodal response in this strain. The analogue exerts a bacteriostatic effect on some cells which remain viable for several hours. The bacteriocidal effect, presumably on cells continuing growth, interferes with cell division by preventing septation.

ISSN:0008-4166    

DOI:10.1139/m71-015

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The antigenic relationship between virulent and attenuated or avirulent human, bovine, and avian strains of mycobacteria has been studied with rabbit immunesera against fractions obtained from mechanically disintegrated bacilli. The antigenic comparison was carried out by Immunoelectrophoresis after cross-absorption of antisera. It was shown that the human virulent strain H37Rv, the bovine virulent strain Ravenel, and the avian virulent strain Sheard had at least two antigens which were not detected in the related attenuated or avirulent strains. Furthermore, these additional antigens were found to be different from strain to strain.The antigenic comparison between human, bovine, and avian strains of mycobacteria revealed that fewer antigenic differences existed between human and bovine than between human or bovine and avian strains.

ISSN:0008-4166    

DOI:10.1139/m71-016

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

L-Cysteine (1.21 mg/ml) inhibited the linear growth ofHelminthosporium carbonum22% at pH 5.5 and 60% at pH 4. The increased toxicity with increasing acidity was attributed, in part, to the increase in the concentration of the cysteine cation [HS—CH2—CH(NH3+)—COOH]. In the presence of chlorogenic acid (1.77 mg/ml),L-cysteine (1.21 mg/ml) was more toxic than when tested alone. This increased toxicity was due to the acidity of chlorogenic acid, which had little or no fungitoxicity when tested alone. Chlorogenic acid did not increase the toxicity ofL-cysteine when the increased acidity was neutralized with base.L-Cysteine at 0.6 mg/ml and 0.3 mg/ml inhibited the growth ofH.carbonum, respectively, 32% and 10% at pH 4.5, and 5% and 1% at pH 5.5. SinceL-cysteine is toxic only at relatively high concentrations, it appears doubtful whether this amino acid contributes significantly to the fungitoxicity of potato peel extracts.

ISSN:0008-4166    

DOI:10.1139/m71-017

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Populations derived fromSalmonella typhimuriumsurviving 1, 5, or 10 exposures to 0.5 Mrad did not show any increase in resistance to antibiotic discs containing 5 μg of tetracycline, 5 μg of chloromycetin, or 50 units of polymyxin. The frequency of resistance to 3 μg of tetracycline, 10 units of ampicillin, 120 μg of chloromycetin, or 30 μg of streptomycin per milliliter of agar, did not increase among progeny derived from either of two strains ofS.typhimuriumsurviving 5–10 exposures to 0.5 Mrad. So, too, the virulence and radiation resistance of three strains ofS.typhimuriumexposed to radiation-growth cycling remained essentially unchanged or decreased.A mixture which originally contained 10 different serotypes ofSalmonellawas cycled at 0.23 Mrad. After 10 exposures the frequency of resistance of the progeny to ampicillin, chloromycetin, and streptomycin increased 87-, 55- and 13-fold respectively. The LD50was essentially the same, but the radiation resistance (Dvalue) increased from 0.053 Mrad in controls to 0.074 Mrad.The evidence presented seems to indicate that mutants are attained more readily fromSalmonellacultures recycled at 0.25 Mrad or less than from those recycled at 0.5 Mrad. The pathogenicity of either one was usually essentially unchanged or reduced.

ISSN:0008-4166    

DOI:10.1139/m71-018

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Evidence is presented that a single enzyme, quercetinase, is responsible for the degradation of quercetin byAspergillus flavusto yield carbon monoxide and a depside, 2-protocatechuoylphloroglucinol carboxylic acid. A procedure for the isolation of the dioxygenase as a homogeneous protein is described. The most purified preparation degraded 10 800 μmoles of quercetin/h mg protein and was homogeneous as judged by ultracentrifugation and by electrophoresis. The molecular weight was determined as 111 000 + 4000.Kmvalues for quercetin and oxygen as substrates were 5.2 × 10−6 Mand 1.2 × 10−4 Mrespectively. The enzyme is a glycoprotein containing 27.5% carbohydrate and the amino acid composition is presented.

ISSN:0008-4166    

DOI:10.1139/m71-019

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Synchronously dividing cultures ofBacillus subtiliswere obtained by harvesting cells from the stationary phase and reincubating them in fresh medium. It was discovered that the first division period was not necessarily synchronous, but when the first synchronous division occurred it involved a reduction in septation. These findings suggested that cell synthesis was directed to more than the forthcoming division, and that synchronization involved a subsequent division and a change in the cell division control mechanism.

ISSN:0008-4166    

DOI:10.1139/m71-020

出版商:NRC Research Press    

年代:1971

数据来源: NRC