摘要:

The processes of gamete fusion, zygote development, and zygote germination inChlamydomonas moewusiiare described. Light, previously shown to be essential for vegetative growth and for sexual activation, also appeared to be required for gamete fusion and for zygote maturation, but not for germination. Fully mature zygospores, enclosed in thick, impermeable walls, germinated erratically; experimental efforts to promote their earlier and more regular germination were unsuccessful. Germination as high as 60 to 90% was achieved by limiting the illumination which the zygotes received during their development.

ISSN:0008-4026    

DOI:10.1139/b57-066

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

Filamentous growths have been observed in various regions of many varieties of higher plants. They have been noted particularly in tissue cultures and in similar locationsin vivo, i.e., where humidity was high and the nutrition appropriate. The reasons for this phenomenon have not been investigated completely although it had been proposed that this represented the initial stages of callus development.This present paper explores the possibility that the outgrowths termed filamentous are the result of two circumstances, a highly humid environment combined with the isolation of the initiating cells either spatially or through the favoring of one cell over its neighbor nutritionally or through other means that would cause a sharp differential in growth rate.

ISSN:0008-4026    

DOI:10.1139/b57-067

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

Size differences were studied in vegetative organs of two purebred strains ofCucurbita pepoL. which differ greatly in size by their genotype.The growth pattern of plants of the selected strains was found to be essen tially the same in the two types. The two strains exhibited great differences in mature organ size, but only small differences in number of organs.No correlation was found between embryo size and mature size. In the early stages of primary shoot development, however, a correlation was found between embryo size and the rate of new organ initiation. This correlation disappeared during the later stages of plant development. The parental strains had similar rates of organ formation, while the crosses showed hybrid vigor with respect to rate of new organ formation.Sizes of the apical meristems and organ primordia were essentially the same in the large and small strains and did not appear to determine mature organ size differences.Development of size differences between the same organs of the two strains and the crosses was found to be mainly due to duration of organ growth. Rates of organ growth differed only slightly between the strains. Increase in size of successively formed organs of the same strain was also found to be mainly due to duration rather than to rate of organ growth.

ISSN:0008-4026    

DOI:10.1139/b57-068

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

Size differences were studied on the cellular level in vegetative organs of two purebred strains ofCucurbita pepoL. which differ greatly in inherited size.Mature organ size has been analyzed for the two strains on the histological and cellular levels with particular emphasis on mature internode size. Differences between the strains in tissue and cell size were observed for the main tissue and cell types. Differences in internode length were determined both by differences in cell size and cell numbers. Cambial activity as expressed in numbers of radial immature derivatives and in number of divisions in the interfascicular regions was found to be much greater in CF than in SRC.No important differences were found between the large and small strain in the size of the meristematic and submeristematic regions. Early internode growth in terms of cell division and cell enlargement was also found to be similar in the two strains. It is concluded that the cellular differences found in the mature organ must be due to a longer duration of growth mainly in terms of cell enlargement but also in terms of cell, division. This conclusion is supported by the results obtained on internode growth described in a previous paper.Grafting experiments with apical buds of the two strains did not show any influence of the stock on the scion; mature organ size was determined only by the scion.

ISSN:0008-4026    

DOI:10.1139/b57-069

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

Europhium trinacriformeParker was isolated from 11% of the lesions on western white pine affected with pole blight in the Interior of British Columbia and from 84% of the lesions on white pine on the Coast. This fungus was the only organism isolated more than twice from pole blight lesions and found to be pathogenic to white pine. However, it was unable to cause the pole blight condition within a period of 4 years after inoculation into healthy white pine. When this fungus was placed in wounds on white pine, lesions resulted which were similar to pole blight lesions in shape and in ability to cause resin exudation, but were otherwise dissimilar. On the basis of radial growth analysis it was evident that lesions occur following a general reduction in radial increment, and at the same time, or shortly after, the first crown symptoms of pole blight appear. Radial growth beneath lesions was nearly always less than in other parts of the stem section, indicating that both the position and extent of lesions are determined before they occur. Examinations of the number and size of lesions on pole blighted trees and the results of inoculations, isolations, and histological studies indicated thatE.trinacriformemost likely gains entrance to lesions that are already formed from other causes and extends them.

ISSN:0008-4026    

DOI:10.1139/b57-070

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

Analyses of approximately 2600 living balsam fir, examined at seven localities in the Atlantic Provinces, established that, after adjustment for age, differences in the amount of cull existed between some of the localities. The analyses indicated that the effect of age on trees between 60 and 120 years of age is expressed mainly in the number of trees infected with decay, although in some areas it also has an effect on the amount of butt cull in infected trees. Differences in the amount of trunk cull between localities could be attributed to differences in the number of trees possessing this type of decay. No significant effect of age on the amount of trunk cull in infected trees was found in any locality, nor were there any differences in the amount of trunk cull in these trees among localities. Differences in the amount of butt cull were caused both by the number of trees infected with butt rot and by the amount of cull in infected trees. Some factors have been enumerated which require further study before the causes of such differences can be determined. It is felt that a critical study of the infection courts may disclose reasons for differences in the amount of trunk infection. Butt rot relationships appear to be more complex and an understanding of the causes of the variations encountered can be determined only after further intensive studies.

ISSN:0008-4026    

DOI:10.1139/b57-071

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

The fusiform cambial cells of conifers undergo two types of anticlinal division, pseudotransverse division and division to produce small cells off the side. Pseudotransverse divisions are largely confined to the cambial initials, only a small percentage of such divisions occurring in the derived tissue mother cells. The incidence of pseudotransverse divisions outside the layer of initials tends to rise with the rate of growth. Divisions of the second type, to yield segments off the side, are infrequent and seem generally to involve only the fusiform initials. Behavior of the abscissed segments bears some relationship to size, the shortest segments usually failing, those of intermediate length tending to become reduced to one or more ray initials, and the largest developing as fusiform initials.

ISSN:0008-4026    

DOI:10.1139/b57-072

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

From observations in the field and the results of inoculation experiments it has been discovered thatMilesia laeviuscula(Diet. & Holw.) Faull causes a needle rust on the current year's needles of grand fir (Abies grandis(Dougl.) Lindl.). The rust has been induced repeatedly to fruit on both alternate hosts, licorice fern (Polypodium vulgareL. var.occidentaleHook.) and grand fir, by inoculation, and its pycnial and aecial states are described for the first time. The life history ofMilesia laeviusculais presented. It is noteworthy because of the long period (4 to 5 months) required for maturation of the aecia, because primary infection of the fern takes place largely during late fall and early winter, and because the rust can survive on its fern host independent of its alternate host, grand fir.

ISSN:0008-4026    

DOI:10.1139/b57-073

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

Methods are described for the extraction of total lipids (including pigments) from leaves, under conditions minimizing the action of phosphatidase C on the phosphatides, and for the fractionation of the phosphatide components. The lipids were extracted with hoti-propanol, partitioned into chloroform, and freed from water-soluble substances by washing with water. Chromatography of the lipids on silicic acid – Celite columns yielded a pigment plus non-phosphatide fraction and the following four phosphatide fractions: Fraction I, consisting of inositol–carbohydrate phosphatides; Fraction II, containing mostly phosphatidyl ethanolamine, and some phosphatidyl serine; Fraction III, an unknown phosphatide; and Fraction IV, consisting predominately of phosphatidyl choline. Although the analytical data and the products of hydrolysis of the fractions indicate that complete resolution of the phosphatides has not been achieved, the methods described should be useful as a preliminary group fractionation, prior to further separation and purification steps. The presence of inositol phosphatides in leaves is reported here for the first time.

ISSN:0008-4026    

DOI:10.1139/b57-074

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

The phosphatide content of primary leaves of runner bean increased linearly with time, between the 8th and 20th day of development, at a rate proportional to the growth of the leaves.Detached leaves incorporated C14into the total lipids (pigments, non-phosphatides, and phosphatides) when supplied with C14O2in the light for 1 minute followed by a 30-minute period in the light or dark in tracer-free air and when supplied with pyruvate-2-C14or acetate-1-C14in the light. P32was incorporated into the phosphatides after orthophosphate-P32was supplied both in the light and dark. With each precursor, radioisotope was incorporated into the four phosphatide fractions obtained by chromatography of the total lipids: inositol–carbohydrate phosphatides (Fraction I), phosphatidyl ethanolamine – phosphatidyl serine (Fraction II), an unknown phosphatide (Fraction III), and lecithin (Fraction IV).Distribution of radioactivity among these phosphatide fractions and among the phosphatide moieties varied greatly with the precursor supplied. Thus, with C14O2as precursor, Fraction I and III had the highest specific activities, and C14entered both the water-soluble moieties and the fatty acids in all of the phosphatide fractions. With pyruvate-C14or acetate-C14, lecithin was most highly labelled, and C14was found almost exclusively in the fatty acids of the phosphatides. With orthophosphate-P32, Fraction III had the highest specific activity. The bearing of these findings on the metabolism of phosphatides in leaves is discussed.

ISSN:0008-4026    

DOI:10.1139/b57-075

出版商:NRC Research Press    

年代:1957

数据来源: NRC