摘要:

The formation of 3-acetyldeoxynivalenol (ADON) and other secondary metabolites ofFusarium culmorumin a stirred jar fermentor is described in relation to changes in concentrations of sugars, N, P, and O2, and in pH in the medium as well as changes in cellular parameters. The addition of sodium [1-13C]acetate to the fermentation demonstrated that the conditions used resulted in the biosynthesis of ADON instead of other primary and secondary metabolites such as culmorin, dihydroxycalonectrin, and sambucinol for all but the early stages of the fermentation. Enrichment studies also revealed that dihydroxycalonectrin was not an important intermediate of ADON. Biosynthesis of ADON was apparently induced by nitrogen limitation. At the end of the fermentation, ca. 710 mg L−1ADON was obtained.

ISSN:0008-4026    

DOI:10.1139/b86-001

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

The lichenRamalina menziesiiTayl. shows a clear gradient in morphology from coastal to inland sites. Experiments were conducted to evaluate the impact of this morphological variation on water uptake, water loss, and tensile strength properties. The results show that none of these characters is greatly influenced by morphological variation. Artificial loading of thalli with NaCl altered the wetting and drying responses in the same direction as was found in coastal material. This implies that the presence of elevated intrathallus concentrations of NaCl found near the coast is mainly responsible for the small differences in wetting and drying characteristics. It further implies that the morphological variation seen in the field is not an adaptation to the conditions near the coast but, rather, is the imposed result of a permanently moist, cool, and salty environment.

ISSN:0008-4026    

DOI:10.1139/b86-002

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

Macrophomina phaseolina(Tassi) Goid. is reported as a pathogen of guar in North America for the first time. AlthoughM. phaseolinais seed borne in other crops, the fungus was not recovered from seeds of naturally infected guar plants. Since the pathogen is found in desert and cultivated soils throughout southern Arizona where concurrent heat and water stress favor disease development, charcoal rot should be considered a potential constraint to guar production in arid regions.

ISSN:0008-4026    

DOI:10.1139/b86-003

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

Resistance to flax rustMelampsora lini(Ehrenb.) Lév. in flax carrying theNresistance gene is determined by 24 h postinoculation, at which time hypersensitivity is observed. We have examined protein synthesis in cotyledons inoculated with both virulent and avirulent races of rust byin vivolabelling with [35S]methionine. The pattern of protein synthesis was assessed by one- and two-dimensional electrophoresis 8, 13, and 18 h after inoculation. No changes in protein synthesis were observed in the first 14 h following inoculation; however, by 18 h after inoculation the susceptible combination showed a marked decrease in protein synthesis (22%;P = 0.01). This could be largely accounted for by the reduced synthesis of the ribulose 1,5-bisphosphate carboxylase large subunit, which was readily quantified on electrophoresis gels. In addition, a 30-kDa polypeptide also declined in the susceptible combination. Two-dimensional electrophoresis enabled changes to be detected in the synthesis of other minor polypeptides. None of these changes were observed in the resistant combination in which a small increase in the synthesis of the ribulose 1,5-bisphosphate carboxylase large subunit and the 30-kDa polypeptide was found. These results indicate that the outcome of the host–pathogen interaction has already been determined by 18 h after inoculation.

ISSN:0008-4026    

DOI:10.1139/b86-004

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

The lipid, fatty acid, glucan, protein, and chlorophyll contents of nutrient-starved and nutrient-stressed cells ofCyclotella meneghinianaKütz. were investigated in batch and semicontinuous culture experiments, respectively. In batch culture experiments, cells were removed from nutrient-replete media, resuspended in silicon-, nitrogen-, or phosphorus-deficient media according to a 2 × 3 factorial design in fractional replication, and analyzed 3 and 9 days after transfer to treatment media. Silicon starvation caused a significant increase (300%) in cell protein content. In semicontinuous culture experiments, cells were grown in media with silicon, nitrogen, or phosphorus at concentrations lower than necessary for maximum rates of growth. Within each nutrient experiment, dilution rates of 0.10, 0.25, and 0.50∙day−1produced three distinct rates of nutrient supply per cell. Cell lipid : glucan ratios significantly decreased (50%) with increasing silicon supply rate. Cell lipid, glucan, and protein significantly increased (300%) with increasing nitrogen supply rate. Cell lipid and glucan significantly increased (300 and 400%, respectively) with increasing phosphorus supply rate. Fatty acids of extracted lipids generally possessed carbon chain lengths of 14 to 24. However, carbon chain lengths of fatty acids from silicon-stressed cells ranged from less than 14 to 18. No distinct differences in fatty acid composition were observed among supply rates within silicon- and nitrogen-stressed culture

ISSN:0008-4026    

DOI:10.1139/b86-005

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

A study of the vegetation of the Nanoose – Bonell salt marsh, Vancouver Island, British Columbia, was conducted during the period of May – September 1978. A total of 49 species of vascular plants was identified, 10 of which dominated the flora of the estuarine marsh. Six of those dominant species (Distichlis spicata,Glaux maritima,Salicornia virginica,Triglochin maritimum,Plantago maritima, andAtriplex patula) are tolerant of high salinities. Eight plant communities were identified and mapped within the study area. Aerial biomass was dominated by that of theCarex– channel edge community with a peak aboveground biomass of 1259 g dry weight/m2. Major factors affecting the occurrence and distribution of species within the marsh were salinity of the inundating water, elevation of the marsh platform, and soil texture.

ISSN:0008-4026    

DOI:10.1139/b86-006

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

Percentages of original dry mass lost annually and single exponential decay rates (k) for timothy (Phleum pratenseL.) leaf litter decomposing on three reclaimed subalpine mine spoil plots (7, 3, and 1 years old) in Alberta, Canada, were compared with values predicted using generalized equations devised by Meentemeyer on the basis of an annual regional average of actual evapotranspiration (Thornthwaite) and a site-specific value (Christiansen). Measured decay rates on the more heavily vegetated plots (3 and 7 years old) were similar tokvalues predicted using Christiansen actual evapotranspiration values, while the decay rate on the plot with the least amount of vegetation cover (1 year old) was much greater thankvalues predicted using Christiansen or Thornthwaite actual evapotranspiration values. The actual evapotranspiration model severely underestimated annual percentage mass losses, regardless of whether Thornthwaite or Christiansen actual evapotranspiration values were used.

ISSN:0008-4026    

DOI:10.1139/b86-007

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

Optimal conditions of pH and substrate concentration for five enzymes from crude extracts of needle and bud tissue of a white spruce (Picea glauca(Moench) Voss) tree were first investigated, and then used for subsequent experiments. With increasing age of the needles on the tree, activity of peroxidase increased, while that of 6-phosphogluconic acid dehydrogenase and ferredoxin-NADP+reductase decreased. Polyethylene glycol increased enzyme activity from needle tissue. For isocitrate dehydrogenase and glucose-6-phosphate dehydrogenase, 2% polyethylene glycol was most effective, while for 6-phosphogluconic acid dehydrogenase, 4% was best. Enzyme activity also varied considerably with the pH of the extraction buffer. Extraction of needle and bark tissues with various combination buffers referred to in the literature clearly indicated that no one extraction buffer was optimal for all five enzymes of this study. Unlike that of needle and bark tissues, enzyme activity of bud tissues was high even in the absence of any protective agent. The effect on enzyme activity of storage of the bud extracts for 10 days at 4 °C varied with the enzyme.

ISSN:0008-4026    

DOI:10.1139/b86-008

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

A numerical examination was conducted of the relationships among 99 morphological characters, geographical distribution, and ability to hybridize among the 55 species of the Old World genusMedicago(Leguminosae) currently recognized. Nearest morphological neighbours were found to be much more likely to be crossable than other species combinations. More than half of the species combinations proved to have sympatric geographical ranges. Sympatric species were not found to be significantly more crossable than nonsympatric species. Sympatry was not found to be significantly different in frequency among closely related species than among less closely related species. Using Lefkovitch's measure of biogeographical distance, a positive relationship between morphological divergence and geographical separation was demonstrated. However, the relationship was not strong. This may be due to the very large mean intercentroid distance found between the 54 pairs of nearest morphological neighbours, about 2800 km. This suggests that geographical divergence has developed so extensively between even the most closely related species ofMedicagothat random species migrations have substantially obscured relationships.

ISSN:0008-4026    

DOI:10.1139/b86-009

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

An automated data bank for Canadian grass genera has been established in Ottawa under the DELTA system, capable of generating detailed taxonomic descriptions and identification keys in English and French. The descriptive information available comprises 274 characters, mainly concerned with morphology, anatomy, physiology, and geographic distribution. The present capabilities of the system are described and illustrated by automatically typeset sample keys to the 109 genera known to occur in Canada (in English) and to the taxa of the Yukon (in English) and to those of Québec (in French); by automatically typeset sample descriptions of the genusFestucain computer-coded form (in English and in French); and by two microfiches carrying descriptions and keys for all the Canadian genera (in English and in French).

ISSN:0008-4026    

DOI:10.1139/b86-010

出版商:NRC Research Press    

年代:1986

数据来源: NRC