摘要:

Uredospores ofPuccinia graminisvar.tritici(race 56) were analyzed quantitatively for total free amino acids and ninhydrin-positive substances by ion-exchange chromatography. Extracts of these substances were obtained by leaching the spores and by re-extracting leached spores with boiling water. Thirty-five ninhydrin-positive compounds were found and identified. The leach extract differed quantitatively from the extract obtained by boiling although both contained the same 35 substances. It is proposed that there are easily extractable ninhydrin-positive substances coating the spore wall and ninhydrin-positive substances in the protoplasm that can be extracted only with difficulty.

ISSN:0008-4026    

DOI:10.1139/b65-077

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

TwoScenedesmusspecies were studied in culture in the laboratory and incubated in nature. When the organisms were suspended in sterile Büchner funnels or dialysis sacs in nature, results were similar to those for certain laboratory experiments. In nature there was suppression of spine production with one species; similar results were obtained with older laboratory cultures. With a secondScenedesmussp., unicells were commonly produced in nature, as well as in several media in the laboratory.

ISSN:0008-4026    

DOI:10.1139/b65-078

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Growth of the planktonic, euryhaline diatom (Bacillariophyceae)Thalassiosira fluviatilis, both in nature and in culture, is accompanied by the production of a large amount of extracellular "mucilage". This mucilagenous condition is due to the formation of long, narrow fibers, composed of a number of microfibrils, which originate from the marginal and central pores in the silica valves. These fibers, previously referred to as mucilage or slime threads, were found upon hydrolysis to be composed entirely of glucosamine residues. Evidence will be presented in a subsequent paper (20) to show that these fibers consist entirely ofpure, crystallinepoly-N-acetyl-D-glucosamine linked by β-(1→4) bonds. This polymer has been given the systematic namechitanto distinguish it from chitin as isolated from other sources. This is the first report of the occurrence of this glycan in diatoms, and in a pure crystalline state in nature. The chitan was localized in the extracellular fibers, and was not found as part of the protoplasmic constituents. Approximately 18% of the nitrogen added to the culture medium was incorporated into the chitan fibers, which, in turn, comprised 31–38% of the cellular material (including the silica) of this diatom. Methods of production and isolation of the fibers are described, together with a discussion of the nature of the fibers as derived from light and electron microscopic observations. The presence of chitin in other algae also is discussed.

ISSN:0008-4026    

DOI:10.1139/b65-079

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Chromosome numbers are reported for 65 collections representing 30 species ofSenecio. The following chromosome numbers are reported for the first time:S. antennariifolius, n = 23;S. bolanderi, n = 23;S. capitatus, n = 20;S. elmeri, n = 20;S. erucifolius, n = 20;S. flettii, n = 20;S. litvinovii, n = 20;S. megacephalus, n = 20;S. pseudaureus, n = 20 andn = 40;S. robbinsii, n = 23;S. rupester, n = 10;S. uniflorus, n = 20; andS. websteri, n = 20. A relatively high incidence of intraspecific polyploidy is reported with six Northwest species exhibiting the phenomenon.

ISSN:0008-4026    

DOI:10.1139/b65-080

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

A previously unreported member of the section Bromopsis, having taxonomic similarities toB. pumpellianusandB. pacificus, was recently found in westcentral Alaska. Its relationship to these species and toB. inermisandB. ciliatushas been investigated. Both this unreported member (Bromus X)andB. pacificuswere shown for the first time to be tetraploids (2n = 28); forms ofB. ciliatusoriginating in Russia and North America were diploids (2n = 14); and a number of AlaskanB. pumpellianuswere octoploids (2n = 56). Chromosomes with large satellites were found inBromus X, B. pumpellianus, and a tetraploid form ofB. inermisbut not inB. pacificusorB. ciliatus. Seed was produced and hybrids resulted from crosses ofBromus XwithB. pumpellianusand tetraploidB. inermisbut no seed developed from crosses withB. pacificusandB. ciliatus. A relatively high frequency of stainable pollen among the hybrids suggested that they were partially fertile. It was concluded thatBromus Xwas a very close relative ofB. pumpellianusandB. inermisbut was not closely related toB. pacificusorB. ciliatus.

ISSN:0008-4026    

DOI:10.1139/b65-081

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

An extensive dieback and canker disease of chestnut oak (Quercus prinusL.) in Pennsylvania was proved to be caused byBotryodiplodiasp. Isolations from infected stems, branches, buds, and petioles, many of which displayed stromata ofBotryodiplodiasp., yielded cultures of this fungus. Inoculations of chestnut oak seedlings and saplings withBotryodiplodiasp. induced symptoms identical with those observed in nature. The fungus was subsequently reisolated from the inoculated diseased tissues. Symptoms occurring in nature were foliar blight, branch dieback, and branch canker. Extensive foliar symptoms, which appeared in late spring and early summer, probably resulted from infections which took place late in the previous summer or fall. Frequent association of a scale insect,Asterolecaniumsp., with the disease implicated it as a contributing factor in the disease cycle. Maximum radial growth of the fungus on cornmeal and Bacto yeast nitrogen base agar occurred at 20 and 25 °C, respectively. Light was necessary for the production of stromata and conidia in culture. Microtome sections of petri dish cultures and diseased twigs showed that the fruiting structures of the pathogen were uni- or multi-locule pycnidial stromata. The stromata averaged 400–500 μ. in cross section and contained conidia which at maturity were brown, one-septate, and measured 13 × 27 μ.

ISSN:0008-4026    

DOI:10.1139/b65-082

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Excised primary leaves of Little Club and Khapli wheats were allowed to senesce on water or on kinetin (10 mg/l.) for 6 to 8 days. Histological sections taken at 2-day intervals were stained for RNA, DNA, histone, and total protein. Twenty-five or thirty leaves were analyzed daily for chlorophyll, protein, and nucleic acids. Oxygen uptake was also measured. Examination of the sections showed that leaves senescing on water underwent rapid losses in chloroplast RNA and protein and in nuclear RNA. Losses in DNA, histone, and total nuclear protein were delayed until the nuclei disintegrated. These observations are correlated with the analytical results. The latter revealed statistically significant losses in chlorophyll, protein, and nucleic acid contents with time. The losses in nucleic acids were due mainly, if not entirely, to losses in RNA. Oxygen uptake per gram fresh weight in the leaves on water did not change significantly with days after excision. Kinetin significantly delayed losses in chlorophyll, RNA, and protein, and depressed oxygen uptake. Certain differences between the two varieties of wheat are described, including the more rapid loss of nucleic acid in Khapli.

ISSN:0008-4026    

DOI:10.1139/b65-083

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Detached leaves of Little Club wheat were allowed to senesce on water or on kinetin (10 mg/l.) in petri dishes on the laboratory bench. Samples taken at intervals of 24 to 48 hours for 8 to 10 days were fixed in permanganate or osmium tetroxide, embedded, usually in araldite or epon, and examined by electron microscopy. Abnormalities were noted in the endoplasmic reticulum (ER) of the mesophyll cells 2 days after the leaves were detached; ER and cytoplasmic ribosomes were not present after 4 or 5 days. Swelling of the mitochondria and degeneration of the cristae, collapse of the chloroplast grana, and abnormalities in nuclear structure were noted after 3 days. Vacuolar contraction occurred in some cells after 4 days but the plasma membrane usually remained unbroken until the seventh or eighth day, by which time the mitochondria were no longer recognizable and most of the chloroplasts and nuclei had also disintegrated.Kinetin induced an increase in the amount of ER and ribosomes and markedly delayed the degeneration of cellular fine structure.

ISSN:0008-4026    

DOI:10.1139/b65-084

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

An investigation was carried out to determine the factor or factors causing the paucity of reproduction by seeds ofFagus grandifoliain southern Wisconsin, as contrasted with the relatively abundant reproduction by seed in the northern part of the state. A greater percentage of viable seed was found to occur in northern conifer–hardwood forests than in southern hardwood forests. The results of in vitro tests suggested that pollen from trees in northern conifer–hardwood forests has a higher percentage germination and produces longer pollen tubes than that from trees found in southern hardwood forests. Parthenocarpic development was observed but the seeds from such fruits were not viable. Quantitative studies on seedling survival showed higher survival rates in the mor humus of northern conifer–hardwood stands than in the mul humus of southern hardwood stands. The study suggests that the relatively high success of beech reproduction by seeds in northern conifer–hardwood forests is related to both higher seed viability and more favorable conditions for seed germination and seedling survival. Geographic location of stands appears less important than forest type to the success of beech reproduction by seed.

ISSN:0008-4026    

DOI:10.1139/b65-085

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

InHypomyces solanif.cucurbitaethe inhibitory effect of diphenyl on spore germination, germ tube development, and subsequent growth was overcome by mutation to chloronitrobenzene tolerance at any of three previously known loci. Sectoring under the selective action of diphenyl similarly resulted in tolerance to chloronitrobenzenes. One mutant gene is sufficient to give the maximum diphenyl tolerance possible. Results of cross-tolerance tests with differentially sensitive strains of three other fungi showed the same relationship between diphenyl tolerance and chloronitrobenzene tolerance. Neither volatilities nor relative saturations were found to be of importance in an understanding of the reason for this relationship. Diphenyl-tolerant strains are also tolerant to compounds derived from diphenyl by simple substitutions. The magnitude of the tolerance may be influenced by the substituent, the position, and the fungus species.

ISSN:0008-4026    

DOI:10.1139/b65-086

出版商:NRC Research Press    

年代:1965

数据来源: NRC