摘要:

Coprotus baeosporus, Fimaria trochospora, andIodophanus venezuelensisare described and illustrated. A revised description is provided forThelebolus caninusn. comb. (=Ascobolus caninusAuersw.). Additional records of many previously recognized Pezizales are reported.

ISSN:0008-4026    

DOI:10.1139/b77-336

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

In experiments carried out in a water-vapour-saturated atmosphere, the photosynthesis of submerged leaves ofPotamogetonandMyriophyllumwas light saturated at a quantum flux of 200 μE m−2 s−1. Saturation of photosynthesis with CO2, however, could not be achieved, even at 3500 μl ℓ−1CO2. In contrast, floating or aerial leaves of these plants showed saturation with light only at or above a quantum flux of 1200 μE m−2 s−1. In floating leaves ofPotamogetonphotosynthesis was saturated at 1000 μl ℓ−1CO2and in aerial leaves ofMyriophyllumsaturation was being approached at 2100 μl ℓ−1CO2.The high resistance of submerged leaves to CO2transfer makes accurate measurements of photosynthesis and photorespiration difficult. Apparent photosynthesis, though, was stimulated in 2% O2and inhibited in 50% O2compared with the rates in air. Oxygen sensitive CO2evolution into CO2-free air in the light was measured and compensation points of 31 to 75 μl ℓ−1CO2were determined. These observations indicate that photorespiration exists in submerged aquatic vascular plants, but the rate of the process cannot be accurately m

ISSN:0008-4026    

DOI:10.1139/b77-337

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

One hundred and seven sunflower selections were examined by gas-exchange techniques for variations in photorespiration and photosynthesis. Photorespiration was positively correlated(r = 0.73) with true photosynthesis and constituted 14.3% of true photosynthesis or 16.7% of apparent photosynthesis.Selections with differences in compensation point or in the sensitivity of photosynthesis to oxygen or carbon dioxide which would be useful for further studies were not found. Photorespiration would seem to be closely linked to photosynthesis.

ISSN:0008-4026    

DOI:10.1139/b77-338

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The terminal or intercalary conidiogenous cells ofTorula graminisare monoblastic and integrated on micronematous conidiophores. The conidia are phragmosporous and consist of simple or branched chains of acrogenous, brown, minutely verruculose cells which frequently fragment into one- or many-celled segments.Torula graminisdiffers fromT. herbarum, the type species ofTorula, in lacking the diagnostic coronate conidiogenous cell that is characteristic of the genusTorulaand is, therefore, placed in the new Hyphomycete genusRutola, asRutola graminisn.comb.

ISSN:0008-4026    

DOI:10.1139/b77-339

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Nuclear fusion occurs in less than 1% of the myxamoebae ofEchinostelium minutumde Bary, isolate D-3, sublines 1965 and 1971. Binucleate amoebae undergo synchronous mitosis, the two nuclei fuse, the fusion nucleus divides, cytokinesis occurs, and uninucleate daughter cells are formed. Failure to find a haploid–diploid alternance between the amoebal and plasmodial phases using Feulgen cytophotometry suggests that nuclear fusion is not a prerequisite for plasmodial formation in this isolate. Nuclear fusion may be one of the mechanisms which has led to the polyploid condition of the 1971 subline. This phenomenon may also represent a parasexual process.

ISSN:0008-4026    

DOI:10.1139/b77-340

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Hybrid embryos, derived from the cross combining aHordeum jubatum(4x) –H. compressum(2x) amphiploid andH. vulgare(4x), were observed and found to exhibit instability of chromosome numbers that resulted in an overall loss during the first 8 days of development in embryonic tissues. This instability seemed to be manifest as a progressive increase in the variability of chromosome numbers over this developmental period. The change in the overall mean chromosome number followed no discernible pattern with the exception that counts appeared to be clustered at numbers which are exact multiples of the basic chromosome number (x = 7). For each day postpollination, however, the mean chromosome numbers were significantly lower than the expected zygotic number (with one exception), indicative of net chromosome loss. Based on the data presented and cytological evidence, possible mechanisms are proposed to account for chromosome elimination in hybrid tissues. Chromosome loss may result from an incompatible interaction of the chromosomes and spindle-timing determinants originating from each genome during development or as a consequence of the malfunctioning of a proposed cytoplasmic organelle.

ISSN:0008-4026    

DOI:10.1139/b77-341

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Cell size and arrangement in layers of terminal late xylem parenchyma were interpreted as an historical record of certain types of divisions in the cambium. This allowed study of anticlinal divisions of fusiform initial cells in the cambium ofFraxinus excelsiorL. Two types of anticlinal divisions were recognized: oblique (pseudotransverse) and radial (longitudinal). Type designation is, however, arbitrary, since many intermediate configurations between oblique and radial were found. With the exception of radial–lateral divisions, both oblique and radial divisions can be classified as of the left (S) or right (Z) orientational type. The types were nonrandomly distributed. A statistically significant inverse relation was found between the relative length of the anticlinal partition (RLAP) and the length of the dividing cell. Thus, short cells tend to divide radially and longer ones to divide obliquely. As an indirect result,Fraxinuscambium is a mosaic of storied and nonstoried local areas. Consequently,Fraxinuscambium, having an average (but highly variable) RLAP of just over 50%, represents an intermediate between the storied and nonstoried condition.

ISSN:0008-4026    

DOI:10.1139/b77-342

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Basidiospores of species representing each of the five genera in the fungus family Nidulariaceae when examined and photographed using the scanning electron microscope appear to have smooth surfaces. Among the species chosen for study, those representingMycocalia, Nidularia, andNidulaall possess spores which bear a hilum, which has apparently been overlooked in examinations based on light microscopy.

ISSN:0008-4026    

DOI:10.1139/b77-343

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Protoplasts ofEntomophthora egressaMacLeod and Tyrrell were grown in Grace's medium and in two simplified liquid media. These latter media contained reduced numbers of amino acids as compared with Grace's insect tissue culture medium. The pattern of protoplast regeneration was the same in all three media used, but additional stages in the morphogenetic sequence werefound. A spherical mesoprotoplast and an elliptical mesoprotoplast stage with actively moving filopodia were detected early in the growth cycle. The clumping of rod-shaped and spherical hyphal bodies was observed. Mycelial development was very pronounced by 89 h of incubation. The osmolarity and pH of the media were unchanged before this time. The individual hyphae were predominantly initiated by spherical hyphal bodies.All stages of regeneration produced spindle-shaped protoplasts when added to fresh media. The inoculation of spent media with spindle-shaped protoplasts favoured an accelerated morpho-genesis of the cells through the presently reported stages.

ISSN:0008-4026    

DOI:10.1139/b77-344

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

A predatoryNematoctonusspecies (N90) isolated from farmyard soil in Ontario produced gill-forming basidiocarps ofHohenbueheliaon potato dextrose agar. In the presence of nematodes, discharged basidiospores germinated to produce short aerial stalks with terminal adhesive knobs. Germinated basidiospores adhered to the cuticle of nematodes to initiate monokaryotic infection cycles. Multiple basidiospore infections on a single host resulted in dikaryotization in the host body. Crossing single basidiospore cultures demonstrated bipolar sexuality for this species ofHohenbuehelia. The implications of these findings are discussed.

ISSN:0008-4026    

DOI:10.1139/b77-345

出版商:NRC Research Press    

年代:1977

数据来源: NRC