摘要:

Bean leaves were supplied14CO2in light or darkness. After a brief flush, the total and specific radioactivity of respired CO2were measured when leaves were kept in light or darkness either in air or in CO2-free air. Changes in the specific radioactivity of respired CO2show that photorespiration and dark respiration are different processes having different and separate substrates. Little, if any, CO2production by the process of photorespiration could be detected in darkness. The process of dark respiration was about 75% suppressed in light. Measurements of ATP levels in light or darkness and in air or CO2-free air suggest that dark respiration is controlled by photosynthetically produced ATP. This is supported by the fact that isolated intact spinach chloroplasts transfer most of their photosynthetically produced ATP to the medium.

ISSN:0008-4026    

DOI:10.1139/b74-085

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The first record of an algal red snow from Ontario is reported. The organism causing the red snow is identified as the dinoflagellateGymnodinium pascheri(Suchlandt) Schiller; this is the first record of this plant in North America.

ISSN:0008-4026    

DOI:10.1139/b74-086

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Three species ofLaeticorticiumare described as new:L. canfieldiifrom Arizona;L. durangensisfrom Mexico; andL. mississippiensisfrom Mississippi.

ISSN:0008-4026    

DOI:10.1139/b74-087

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Chromosome counts in gametophytes and sporophylls ofAlariacollected in the St. Lawrence Estuary show that all the specimens of this genus in eastern Canada may not belong to the single speciesA. esculentaGreville. Indeed, the haploid chromosome number (n) found in these algae is equal to half of the number attributed in the literature toAlaria esculentafrom the British coasts. Three hypotheses for the interpretation of these observations are considered. The solution of the problem of the identity ofAlariacan only be hoped for from their global, morphological, and biosystematic study.

ISSN:0008-4026    

DOI:10.1139/b74-088

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Eighteen long-established strains of bleachedEuglena gracilis(the products of several different bleaching techniques) and two culture-collection stocks of the naturally colorlessAstasia longawere examined with electron microscope for the possible presence of plastids. Proplastid-like structures were observed in all but three of the bleachedE. gracilisstrains; none was seen in theA. longastocks. None of the presumptive aplastidic strains appears capable of the extensive carotenoid synthesis seen in some of the other bleachedE. gracilisstocks. There was no detectable chlorophyll(ide) in any of the several stocks examined, despite the presence of plastids.

ISSN:0008-4026    

DOI:10.1139/b74-089

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The namePseudoditrichum mirabileSteere et Iwatsuki is proposed for a minute moss with leafy stem 1-3 mm high and seta 6 mm long; it was collected on calcareous silt near the Sloan River, Great Bear Lake, Northwest Territories, only a few miles south of the Arctic Circle. The gametophytic characters agree well with those of the Ditrichaceae, a relatively primitive family, but the peristome is clearly double, with the inner and outer teeth opposite, which thereby indicates a much more advanced phylogenetic position, perhaps at the evolutionary level of the Funariaceae. As the combination of gametophytic and sporophytic characteristics exhibited by this moss does not occur in any existing family of mosses, it is therefore deemed necessary to create the new familyPseudoditrichaceaefor the new genus and species described here.

ISSN:0008-4026    

DOI:10.1139/b74-090

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Incorporation of nicotinic acid-7-14C into nicotinamide adenine dinucleotide by the trifoliate leaves of the bean plant (Phaseolus vulgarisL. var. Brittle Wax) was studied for varying time periods from 5 min to 48 h. Nine radioactive compounds were isolated and identified as all the possible intermediates of NAD metabolism operating in a cyclic pattern. All the intermediates were labelled rapidly and N-methyl nicotinic acid (trigonelline) was detected within 5 min. About 80% of the nicotinic acid fed was accumulated in trigonelline. Senescence induced by floating detached leaves on water enhanced incorporation of the label into nucleotides, NAD > NADP. Treatment with growth regulators altered the NAD/NADP ratios. Benzimidazole and kinetin enhanced NADP synthesis while benzyladenine and ethionine reduced NADP synthesis. The regulator-mediated NADP synthesis is enhanced by light and appears to be inversely related to the synthesis of trigonelline.

ISSN:0008-4026    

DOI:10.1139/b74-091

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The effect of chloroplatinic acid on the growth of the unicellular green algaChlamydomonas eugametoshas been studied. This platinum compound reduces the rate of cell division and induces palmelloid formation by preventing the liberation of dividing cells. Recovery from the chloroplatinic-acid effect occurs after removal of the compound from the medium.

ISSN:0008-4026    

DOI:10.1139/b74-092

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Nitrate-reducing ability, NO2−-reducing ability, and glutamic acid dehydrogenase levels were measured in two clones ofNodularia spumigenaMertens. Measurements with whole cells of both clones show that NO3−reduction is stimulated by NO3−, and that NO2−reduction is probably stimulated by NO2−. The NO3−-reducing system is stimulated by light and inhibited by NH4+. These controls and possible control over NH4+incorporation into amino acids are compared to systems operative in other organisms.Differences in growth and physiology of the clones in growth rate on N-free medium, growth inhibition by urea, and NO2−accumulation in the medium are discussed.

ISSN:0008-4026    

DOI:10.1139/b74-093

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

In the presence of phosphoenolpyruvate, cell-free preparations from distinct annual ring tissues of the trunk and the root ofRobinia pseudoacaciaL. incorporate14CO2into organic compounds. The CO2fixation process exhibits a pH optimum at 7.8 and is activated by Mg2+. Aspartic acid contained 97% of the radioactivity incorporated. Oligosaccharides, malic acid, fumaric acid, glutamic acid, and three substances not identified with certainty show minor labeling. The activities of malate dehydrogenase (EC. 1.1.1.37), aspartate aminotransferase (EC. 2.6.1.1), and "malic enzyme" (EC. 1.1.1.40), involved in the further metabolism of the primary CO2fixation product oxaloacetate, were detected spectrophotometrically in preparations from different annual rings of the trunk. Compared with the outer zones, the innermost part of the sapwood shows only little activity of these enzymes. The capacity to transfer CO2into organic compounds decreases in the radial direction of both trunk and root wood. Heartwood preparations exhibit no CO2fixation. In comparison to the trunk, the wood of the root shows only little dark CO2fixation. The possible physiological role of this nonautotrophic CO2binding in the wood ofRobiniais discussed.

ISSN:0008-4026    

DOI:10.1139/b74-094

出版商:NRC Research Press    

年代:1974

数据来源: NRC