摘要:

This paper reinvestigates the gross changes which follow the inoculation ofProteus mirabilisonto an agar plate. The sequence of development observed by earlier workers was confirmed: namely, the development of a primary colony at the site of inoculation, followed by alternating periods of swarming and consolidation. The paper"s main contribution is the demonstration, by means of time-lapse photography through the phase-contrast microscope, of the cellular changes which occur during the various stages—in particular, the differentiation of short rods into swarmers, the swarming process itself, the subsequent breakdown of the swarmers into progressively shorter units, and the multiplication of these rods. Of special note is the clear demonstration that most of the swarmers are normal viable cells.

ISSN:0008-4166    

DOI:10.1139/m64-001

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Oxygen uptake by whole cells or lysed cells ofA.xylinumat pH 8.0 is only 3% of that of the same preparation at pH 6.0. Because the amount of cellulose synthesized by both types of preparation is the same at pH 6.0 and pH 8.0, not more than 3% of the oxygen uptake of cells ofA.xylinumat pH 6.0 is directly linked to cellulose formation. When tomato supernatant is used as a substrate at pH 6.0 an increase in cellulose synthesis is accompanied by a decrease in oxygen uptake by whole cells. Even at constant pH, oxygen consumption is therefore a poor measure of cellulose synthesis. In spite of the large fractions of available glucose incorporated into cellulose, only a very small part of the total metabolism of the organism is devoted to synthesis of cellulose.

ISSN:0008-4166    

DOI:10.1139/m64-002

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Analyses of seed samples ofPinus banksianaLamb.,P.contortaDougl. var.latifoliaEngelm., andPicea glauca(Moench) Voss demonstrated the presence of 12 genera of fungi.Pythium,Phytophthora, andRhizoctoniawere not isolated but typical symptoms of damping-off disease were observed among the seedlings grown in sterilized soil. Surface sterilization of seeds resulted in a significant reduction in emergence ofP.banksianaandP.glaucaseedlings but not onP.contortavar.latifolia. The cause of this difference is discussed. The post-emergence mortality ofP.banksianaseedlings resulting from surface-sterilized seeds grown in sterilized and unsterilized soil was significantly higher than that among the seedlings from untreated seeds. Mortality ofP.contortavar.latifoliaseedlings was significantly higher among the seedlings from untreated seeds, and that ofP.glaucaseedlings was higher among the seedlings from untreated seeds and only in unsterilized soil.

ISSN:0008-4166    

DOI:10.1139/m64-003

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

The fatty acids ofTrichophyton rubrumwere investigated by gas liquid and by paper chromatography and chemical degradation. Palmitic, stearic, oleic, and linoleic acids are the principal ones in this organism, with linoleic acid predominating. Behenic acid was detected by paper chromatography.

ISSN:0008-4166    

DOI:10.1139/m64-004

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Nine methods for disrupting the mycelium ofNeurospora crassahave been compared. Protein percentages are calculated per gram dry weight of mycelium. A TPN-specific glutamic acid dehydrogenase was extracted and the efficiency of each extraction method is given as total enzyme extracted and specific activity. In terms of total protein, total enzyme, and practicality of the method, the Hughes Press, the French Press and the Raper–Hyatt Press were found to be the most efficient. The advantages and limitations of each method are considered.

ISSN:0008-4166    

DOI:10.1139/m64-005

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

The influence of actinomycetes, bacteria, and fungi onAphelenchoides parietinus(Bastian, 1865) Steiner, 1932, a fungus-feeding nematode, was studied. Thirty percent of the actinomycete cultures tested showed some "attraction" for this nematode on agar plates. The filtrates from a number of these actinomycete cultures favored accumulation of nematodes on areas of agar on which the fluids were spotted. In some instances the nematodes were repelled from these areas. Of the 60 bacterial isolates from rhizosphere soil only one "attracted" the nematode; most of the others repelled it. The filtrates from most of these bacterial cultures were similarly unfavorable. The nematode aggregated strongly around 43 of 54 cultures of fungi, and propagated on 32 of these. The results suggest that the microflora of the root zone may exert a marked effect on the accumulation of this nematode therein.

ISSN:0008-4166    

DOI:10.1139/m64-006

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Cell wall replication ofBacillus cereusandBacillus megateriumwas studied by differential labelling with fluorescent and non-fluorescent antibody.Growth of new cell wall inB.cereuswas initiated near the poles. In the old wall, additional new wall segments gradually developed to form an alternating pattern of new and old wall segments. Further growth elongated the new wall and pushed the old segments apart. Separation of daughter cells appeared to involve splitting of the transverse septa laid down at or near the old wall segments.Growth of new cell wall ofB.megateriumwas initiated either at one of the poles or at the central area of the cell. Multiple segments of new and old wall appeared along the cell length. Further elongation was followed by formation of transverse septa and separation of daughter cells incorporating either old or new wall segments.Our evidence clearly shows that growth and elongation of the two bacilli do not occur by diffuse intercalation of new cell wall into the old.

ISSN:0008-4166    

DOI:10.1139/m64-007

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Bodies accumulate along a network of fine filaments in polyhedrosis- and granulosis-infected cells and appear to coalesce and form the cores of virus rods. The rods, which may develop singly or in bundles, attach to independently formed double membranes which later envelop them. In each bundle, the rods are oriented in the same direction as they become attached to the membrane. Single rods or bundles of rods migrate or are attracted to areas where polyhedra are formed. The protein material present there surrounds them and crystallizes to form polyhedra. In granulosis infections, single virus rods are surrounded by protein to form capsules.

ISSN:0008-4166    

DOI:10.1139/m64-008

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Passive neutralizing antibodies specific to Coxsackie B-1 virus are transmitted from immune mice to the litters both before and after birth.Before birth the antibodies are transmitted via the mother"s blood; their presence could not be detected by the age of 17 days. After birth, the antibodies apparently are transmitted by milk. The ND50of these antibodies is maintained if the litter is suckled by an immune mother.Although the immune 4-day-old litters survive after intracerebral inoculation and there are no signs of paralysis or other severe damage to the CNS, the brain lesions on microscopical examination appear to be as extensive as in the non-immune controls. The brain tissues of the immune mice are spared if the virus is introduced by the subcutaneous route.The damage observed in the interscapular brown fat in either the immune 4- or the 17-day-old mice, irrespective of the route of virus inoculation, is considerably reduced or minimal, if the presence of the passive antibody can be demonstrated in the blood.When the offspring are born of and suckled by an immune mother, the multiplication of the Coxsackie B-1 virus in the brown fat appears to be completely blocked, and there is no evidence of an immediate antigenic stimulus by the challenge virus.

ISSN:0008-4166    

DOI:10.1139/m64-009

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

not available

ISSN:0008-4166    

DOI:10.1139/m64-010

出版商:NRC Research Press    

年代:1964

数据来源: NRC