摘要:

Attached primary and secondary wheat leaves were supplied continuously with C14O2during daily periods of photosynthesis for 3 days. Samples were analyzed for amounts and total activities of respired carbon, soluble sugars and amino acids, protein amino acids, and protein nitrogen. By labelling all possible protein precursors to the same extent it was possible to eliminate doubts about the specific activity of carbon entering protein. Hence turnover rates could be accurately established. Because tobacco leaves last for a long time, it was possible to label their proteins, wait until soluble compounds were at a low specific activity, and then measure turnover of proteins as radioactivity in them decreased.Protein amino acid turnover rates of 0.4–0.5% per hour were obtained in rapidly growing secondary wheat leaves and 0.2–0.3% per hour in non-growing primary wheat leaves. Turnover rates of 0.15–0.2% per hour were found in expanding tobacco leaves, but little or no turnover was found in fully expanded tobacco leaves.It is suggested that protein turnover is a facet of the biochemical differentiation that accompanies development, enlargement, or change in function of an organ without concomitant net protein synthesis.

ISSN:0008-4026    

DOI:10.1139/b64-001

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

The nuclear cycle in the developing ascus ofRosellinia limoniispora, as revealed in aceto-orcein and acetocarmine smears, follows the general pattern for the higher Ascomycetes: crozier formation, early synapsis of homologous chromosomes in the fusion nucleus followed by nucleolar fusion, rapid elongation of chromosomes and ascus up to late pachytene of prophase I followed by contraction of the chromosomes and nucleolus, and the formation of eight nuclei as a result of two meiotic and one mitotic divisions. The orientation of nuclei in divisions II and III is haphazard. Ascospore delimitation is by simple cleavage of the cytoplasm; no centriole – astral ray mechanism was observed. A nuclear division occurs in each young ascospore, one daughter nucleus being cut off into a cell and degenerating.

ISSN:0008-4026    

DOI:10.1139/b64-002

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Normal, healthy thalli ofFucus vesiculosushave been shown to release into the surrounding medium yellow compounds which absorb ultraviolet light. A study of this phenomenon revealed that brief exposure to elevated temperatures (20 °C) increased the amount of pigment released. There was no difference in the production in light or darkness and only a small decrease with reduced salinity. The amount of pigmentation observed in the medium was directly proportional to the degree of alkalinity from pH 7 to pH 9.A number of other macrophytes and microphytes were examined and only those possessing physodes released substances giving a spectrum similar to that ofF. vesiculosus.Isolation of the material, alkaline hydrolysis, and chromatography revealed phloroglucinol and several unidentified fluorescent substances. It appears that these materials were flavonols or catechin-type tannins.

ISSN:0008-4026    

DOI:10.1139/b64-003

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

The microfloras of slimes present at one location in a paper mill were examined over a 2-year period (1959–1961). The same basic flora was present throughout this time, though the dominant organism varied from one sampling to another. Psychrophilic microorganisms were frequently found. The factors which influence microbial activity in slime are discussed.

ISSN:0008-4026    

DOI:10.1139/b64-004

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Both carnation mottle virus and carnation ring spot virus, hitherto unreported in Canada, were detected in commercial carnation varieties in Ontario. These viruses were distinguished by their effects on the differential hosts,Gomphrena glabasaL. and two selected clonal lines ofDianthus barbatusL., and by their host ranges, physical properties, and serological reactions. Evidence is presented to show that each is identical with the virus of the same name occurring in this crop in England and the United States.

ISSN:0008-4026    

DOI:10.1139/b64-005

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

The growth rates ofLemna minorwere studied under conditions of flashing light of varied durations interacted with continuous illumination of low-intensity far-red and red light, and growth regulators (0.645 p.p.m. kinetin, and 25 p.p.m. IAA). It was found that the growth rate was progressively reduced with decreasing light exposure from continuous illumination to alternating periods of 1-minute intermittency, after which it increased rapidly. The growth rate per unit of light was the most rapid at 0.01-second light period under 1:3 ratio of light to dark. Under 1:1 ratio of light to dark interacted with red and far-red light, kinetin, and IAA, the photosynthetic rate ofLemnawas reduced by far-red but improved by the red light. Kinetin increased the growth rate but IAA inhibited the photosynthetic rate as the number of flashes increased. The IKI test showed that under flashing light old and young fronds stored starch but under continuous illumination, only the older fronds stored starch.

ISSN:0008-4026    

DOI:10.1139/b64-006

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

In Part I of this paper, the principles of numerical taxonomy are discussed and the practical processes outlined, with particular reference to their applicability to the Fungi Imperfecti.In Part II, one of the authors (J.R.P.) discusses several scoring methods, including one introduced by the authors in which a 'primary' character is weighted according to the number of 'secondary' characters used to describe it. The merits of the various methods are considered.In Part III, one of the authors (W.B.K.) discusses the results obtained when 30 strains of Hyphomycetes belonging to theLeptographiumcomplex were compared using a computer, the taxonomic data being scored in six ways. The classification agreeing most closely with the established one was obtained when 'primary' characters were weighted and 'negative matches' were included. Of the methods applied, this is considered in Part II to be the most logically satisfying.

ISSN:0008-4026    

DOI:10.1139/b64-007

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

An account is given of seminatural communities in the Gaspé Peninsula in whichAlchemilla subcrenataBus. is abundant. Evidence is brought forward to show that this species (a segregate of the apomictic complexAlchemilla vulgaris) has been introduced at some period since 1930. It is now completely naturalized. The bearing of this fact on the status ofAlchemillaspecies in North America and in some European areas is briefly considered.

ISSN:0008-4026    

DOI:10.1139/b64-008

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Samples of soil were exposed to gamma radiation from a Co60source. By a modified soil-plate technique fungi were isolated from the radiation-treated soils and compared to those isolated from untreated soils. At intensities of 250, 500, 750, and 1000 kr, 2.53, 0.67, 0.10, and 0.04%, respectively, of the viable propagules of fungi survived. Twenty-eight species of fungi survived soil irradiation of 250 kr or more, many of which were not isolated from untreated soil. Prior gamma irradiation of soil samples enabled isolation of certain fungi that occur in soils in low numbers and that are not ordinarily found on conventional dilution or soil plates. Most of the members of the Moniliaceae, comprising a large portion of the soil fungal population, were killed by radiation, but the Dematiaceae generally were more resistant. It was found that resistance of certain fungal spores in soil to high intensity radiation is related to growth rates of mycelium in pure culture under sublethal levels of continuous radiation. The mycelium of three resistant fungi, which originally survived high doses of radiation, grew better under chronic irradiation than did two susceptible fungi, which were killed by high doses of soil irradiation.

ISSN:0008-4026    

DOI:10.1139/b64-009

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

The exudation of sap from the decapitated stem by solution-cultured root systems of tobacco was measured continuously under constant conditions. The nicotine content of the sap was analyzed as an indicator of solute originating in the root cells. The typical, persistent endogenous rhythm of exudative activity was observed in both volume and nicotine content of sap. The rhythmic control was independent of respiration and of ionic changes designed to influence permeability, but it was reversibly affected by actinomycin D, which implicates DNA function. The removal of potassium or oxygen from the culture solution or the addition of cyanide to it caused a brief transient stimulatory response in exudative rate. Continued anaerobiosis reversibly stimulated exudation in a massive final cycle. These observations support the concept that exudation is a passive phenomenon, of solute leakage and osmosis, dependent on active salt accumulation.

ISSN:0008-4026    

DOI:10.1139/b64-010

出版商:NRC Research Press    

年代:1964

数据来源: NRC