摘要:

The encapsulation material surrounding the endophyte ofAlnus crispavar.mollisFern. root nodule was studied by means of a variety of staining methods in light and in electron microscopy. The enzymatic degradation of the capsular material was obtained and the degradation products were studied by thin-layer chromatography. The endophyte capsule was composed mainly of granular and fibrillar non-sulfated and de-esterified polygalacturonic acid or its salts. An endophyte pectic capsule was also demonstrated in 11 additional species of non-leguminous root nodules. Small secretory vesicles, containing electron-dense material similar to that of the endophyte capsule, occurred in free multivesicular bodies throughout the host cell cytoplasm. Ultrastructural observations are consistent with the view that these bodies migrate to the host membrane envelope surrounding the endophyte, fuse with it, and deposit the contents of the small vesicles toward the endophyte cell wall. These small secretory vesicles appeared to originate as blebs from cisternae tips; dictyosomes were abundant in the infected cortical cells. The possible significance of the pectic capsule in the host–endophyte nutritional interactions is discussed.

ISSN:0008-4026    

DOI:10.1139/b75-219

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Cabbage cultivars which differed in ability to withstand storage showed differential susceptibility toBotrytis cinerea. For a given cultivar, outer leaves on the head were less susceptible than inner leaves, thick areas on leaves were less susceptible than thin areas, and adaxial surfaces of leaves were less susceptible than abaxial surfaces. Uncontrolled variability in rate of decay was reduced by standardizing these parameters. Susceptibility was not related to the location of tissues within individual leaves and appeared to be independent of the dry matter content of tissues.

ISSN:0008-4026    

DOI:10.1139/b75-220

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The macroconidia ofFusarium culmorumcan be produced in a semisynchronous way in continuous culture by manipulating the medium pH. Ultrastructure studies of conidiogenesis have shown that the macroconidia are not conventional phialospores, as has long been believed. The first and subsequent conidia are delimited by the fusion of vesicles in the peripheral cytoplasm in the apex of the conidiophore. The conidium wall, including the basal delimiting septum, is formed endogenously. At a late stage of development the expanding conidium ruptures the conidiophore wall and is released by an abscissional splitting of the basal septum. Internal septation of the conidium normally occurs after its release.

ISSN:0008-4026    

DOI:10.1139/b75-221

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

We present data on a comparison of plasmodesmata in the nodal complexes ofChara corallinaprepared for electron microscopy by chemical fixation of specimens at room temperature and those that have been freeze-substituted. The freeze-substitution technique was applied to intact nodal complexes with the internodal cells on either side intact and showed that most plasmodesmata in the cell walls joining a nodal cell with an internodal cell were free of any occluding substance. We feel that the nonoccluded plasmodesma is the in vivo condition and that previous results using chemical fixation at room temperature where occlusions were reported inNitella translucensandChara corallinaare artifacts of preparation.

ISSN:0008-4026    

DOI:10.1139/b75-222

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

not available

ISSN:0008-4026    

DOI:10.1139/b75-223

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The ultrastructural integrity of adaxial apple leaf cuticles was studied after their isolation from subjacent leaf tissues by several widely used procedures. Cuticles isolated with pectinase and (or) cellulase appeared most similar to the control, non-isolated cuticles. Cutin-embedded microfibrils as well as the lamellar structure of the cuticles were preserved. Cuticles isolated by the zinc chloride – HCl method likewise retained the lamellar structure, but most cutin-embedded microfibrils were dissolved away with this treatment. The ammonium oxalate – oxalic acid reflux procedure for cuticle isolation appeared to yield the most unnatural cuticles. Neither the lamellae nor the cutin-embedded microfibrils were well preserved. Furthermore, the cuticle was fragmented laterally, especially near the anticlinal walls. The importance of understanding what ultrastructural alterations occur during cuticle isolation is discussed with respect to transcuticular movement studies.

ISSN:0008-4026    

DOI:10.1139/b75-224

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Development of plastids in a virescens mutant of ‘Gateway' barley was studied during greening of dark-grown seedlings and in seedlings grown in continuous light. Etioplasts of the mutant did not have a crystalline prolamellar body: however, prolamellar bodies were present in chloroplasts of the 4-day-old mutant when grown in continuous light. Upon illumination, the vesicles within etioplasts and young plastids of the mutant joined together to form grana lamellae and these were formed before the stroma lamellae. Formation of the lamellar system in the mutant was slow and the granal stacks were oriented irregularly rather than being all in the same direction within the plastid.The microtubules seen in the stroma of chloroplasts resembled cytoplasmic microtubules, but they were smaller in diameter and they were unlike them in their fixation properties and cold sensitivity. In the normal, microtubules were present in etioplasts and during formation of the lamellar system. However, in the mutant, they were observed only after formation of the lamellar system. From these findings, it was thought that the microtubules might perform a function in orienting the lamellar system of chloroplasts during their development.

ISSN:0008-4026    

DOI:10.1139/b75-225

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Net changes in weights of P, K, Ca, Mg, B, Fe, Mn, Zn, Cu, Na, Al, Ba, Sr, and Cr in cotyledons and seedling axes ofAcer rubrumL.,Fraxinus pennsylvanicaMarsh., andRobinia pseudoacaciaL. were investigated during early seedling growth. Amounts of elements in embryonic cotyledons varied in the following order:Robinia pseudoacacia>Acer rubrum>Fraxinus pennsylvanica. EmbryonicF.pennsylvanicacotyledons were very small and were embedded in endosperm. When seedlings were grown in the light with no inhibition of photosynthesis, mineral elements were either steadily translocated from cotyledons, accumulated in cotyledons, or initially accumulated in cotyledons and finally exported during cotyledon senescence. Differences depended on specific elements and species. The effects of growing seedlings in the dark or treating seedlings with 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) to inhibit cotyledon photosynthesis were similar in that mineral translocation from cotyledons or accumulation in them was inhibited. Mineral element content in seedling axes increased as dry weights of seedlings increased.

ISSN:0008-4026    

DOI:10.1139/b75-226

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

InOphiorrhiza mungosL. the first division of the microspore nucleus gives rise to a large vegetative nucleus and a smaller generative nucleus. The vegetative nucleus subsequently fragments into a number of irregularly sized particles. These vegetative nuclear bodies move to and flow out of the three germ pores to form three spherical buds on the developing pollen grains. The 'pollen buds' are shed off from the pollen proper before dehiscence. The uninucleate grains readily germinate in vitro, and the single generative nucleus undergoes normal division to give rise to two sperm nuclei.

ISSN:0008-4026    

DOI:10.1139/b75-227

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Translocation of uranin proceeds in the protoplasm ofTradescantiastaminal hairs both in the acropetal and basipetal direction from a wound. A diffusion pattern is observed proportional to the square root of time. It is slower than physical diffusion in water. At any given time interval the number of cells traversed is almost equal whether transport is from the base or the tip. Consequently the distance from the base, where the cells are longer, is also longer. Translocation fits the calculation on a model in which the plasmodesmata in the interconnecting walls are almost occluded with solid obstructions or in which the plasmodesmata are under the influence of a more or less uniform negative charge. Resistance in the plasmodesmata seems to be the limiting factor in this case of symplasmic transport.

ISSN:0008-4026    

DOI:10.1139/b75-228

出版商:NRC Research Press    

年代:1975

数据来源: NRC