摘要:

The unsaturated fatty acids oleic, linoleic, and linolenic induce the formation of the imperfect state of fructification of the Graphium type (coremia) withCeratocystis ulmiandC. piceaeand the Leptographium type withC. penicillata. Intraspecific difference between several strains ofC. ulmishow that linoleic acid is the best inducer with an optimal concentration from 0.05 to 0.20 g/ml of methanol between the 10th and 25th day of culture. Linoleic and linolenic acid extend the capacity of sporulation ofC. penicillata, conserving the strains capability of differentiation of Leptographium structures when ordinarily only the natural substrate can reinduce it.Ceratocystis dryocoetidiscultivated in the same conditions remains insensible to the lipid treatments.

ISSN:0008-4026    

DOI:10.1139/b77-244

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Individual plants ofDicranum fuscescenswere collected from two field sites (a highland semitundra and a lowland lichen woodland) near Schefferville, Quebec (latitude 55° N), for 4½ months during 1974. Collections were made at 2-week intervals from June until the 2nd week in October. Samples were separated into green and brown shoot components and oven-dried. Subsequently analyses were carried out to determine concentrations of total carbohydrates (sugar and starch) and lipids in the respective tissues. Total carbohydrates were found to increase in the green tissues towards the end of the season reaching a maximum of between 10 and 10.5% ash-free tissue dry weight in October. Lipid concentrations showed a maximum of between 3.6 and 4.0% ash-free dry weight during July and subsequently declined, in the same tissues. Seasonal trends of nutrient concentration in the brown portions of the shoot were not marked.An investigation of biomass distribution in complete plants ofD. fuscescensrevealed that brown shoots accounted for more than half of the total. Mean lengths of these parts of the shoot were about twice those of the upper stem.

ISSN:0008-4026    

DOI:10.1139/b77-245

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Isocitrate lyase (EC 4.1.3.1) and isocitrate dehydrogenase (NADP+) (EC 1.1.1.42) activities were detected in cell-free extracts ofChlamydomonas segnisEttl when the alga was grown photoautotrophically with 5% CO2in air (v/v) at 11 klx. When the cultures were either bubbled with air (0.03% CO2), exposed to low light intensity (3 klx), or subjected to manganese or nitrogen deficiency, isocitrate lyase activity was undetectable. During growth in batch cultures provided with 5% CO2, the activity of the dehydrogenase was about 5–12 times greater than the lyase.Using partially purified (about 50-fold) enzyme preparations, isocitrate dehydrogenase (NADP+) showed greater affinity for isocitrate (Km = 0.008 mM) than did isocitrate lyase (Km = 0.1 mM). The dehydrogenase hadKmvalues of 0.011 mMand 0.006 mMfor NADP and Mn2+, respectively. Both enzymes were inhibited by α-ketoglutarate and oxalacetate at 1 mM, but the dehydrogenase was more sensitive to these two keto acids (68–79%) than the lyase (36%). Glycolate at 1 mMinhibited (36%) only the lyase, while glyoxylate had little effect. The dehydrogenase was subject to concerted inhibition by oxalacetate plus glyoxylate (Ki = 0.01 mM). This inhibition was competitive with respect to isocitrate, and preincubation of the enzyme with NADP in absence of isocitrate was necessary for effective inhibition. Each of NADPH (Ki = 0.06 mM) and ATP (Ki = 0.65 mM) was a non-competitive inhibitor (with respect to isocitrate) of isocitrate dehydrogenase (NADP+), and both nucleotides are suggested to be active in the in vivo regulation of isocitrate metabolism inC. segnisduring photoautotrophy.

ISSN:0008-4026    

DOI:10.1139/b77-246

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

A meiotic mutant has been derived from a triploid hybrid of the fern genusCeratopteris. The mutant behavior involves chromosome stickiness that is regularly observed during both meiotic divisions. Chromosome stickiness is also infrequently observed during mitotic division. In addition, the first meiotic division frequently fails and results in the formation of a restitution nucleus. A single second meiotic division follows restitution and results in the production of a dyad of unreduced spores. Viable unreduced spores germinate to produce gametophytes containing the sporophytic number of chromosomes. Spermatozoids produced by the gametophytes are non-functional. However, sporophytes regularly develop apogamously from the gametophytes. Because meiotic reduction and syngamy are absent, the mutants are, reproductively, obligate apomicts.

ISSN:0008-4026    

DOI:10.1139/b77-247

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Equations to estimate gross photosynthesis, respiration, and dry-matter accumulation for soybean from daily estimates of intercepted, photosynthetically active radiation (PAR) were developed from field measurements. We found that gross photosynthesis was a function of intercepted PAR and that 24-h dark respiration was a function of gross photosynthesis. In addition, we developed equations relating intercepted PAR to leaf area index (LAI) and solar radiation. We assumed that gross photosynthesis was reduced when soil-water depletion was greater than 65%. The growth model predicted accumulated dry matter for soybean in 1974, 1975, and 1976 to within 2.7 mg cm−2of observed values.

ISSN:0008-4026    

DOI:10.1139/b77-248

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

A dematiaceous hyphomycete,Bahusutrabeeja dwayagen. et sp. nov., collected on twigs ofCojfea arabicafrom India, is described and illustrated.

ISSN:0008-4026    

DOI:10.1139/b77-249

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Transmission and scanning electron microscopy were used to study the development ofSyncephalis sphaerica(Piptocephalidaceae, Mucorales) merosporangia. Merosporangia were initiated as simple evaginations of the ampulla wall. Three spores were cleaved out of each merosporangial protoplast by invaginations of the merosporangial plasmalemma. An abscission zone was formed in each cleavage zone. A fibrillar spore wall was laid down between the spore plasmalemma and the inner lining layer of the merosporangial wall. Portions of the outer merosporangial wall remained attached to the spore at the time of detachment. During late cleavage, a wall was laid down on the surface of the ampulla at the base of each merosporangium forming a scar. Mature spores remained associated with the ampulla as a spore drop.

ISSN:0008-4026    

DOI:10.1139/b77-250

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

In Lake Opinicon, Frontenac County, Ontario, the temperature gradient at midday from 10 cm below the water surface to soil, in clear weather in August, was found to be 10 Celsius degrees (C°)/m in shallow water where there was a large macrophyte biomass and only 0.2 C°/m in deeper water with fewer plants. There was a direct correlation between the log of the biomass per cubic metre and the steepness of the gradient. Reference is made to temperature gradients developed in calm weather during phytoplankton blooms in Scottish lakes.The biomass of aquatic macrophytes growing in a heated greenhouse in tubs with a capacity of 1 m3increased from early January to the end of February. With increased biomass, the temperature gradient became larger. The size of the gradient correlated with the incoming radiation. Temperature gradients within large populations of the pondweedPotamogeton richardsoniiwere enhanced by low temperatures near the bottom.Diurnally produced temperature gradients with an algae bloom in the same tubs in the open in late June showed strong correlation with solar radiation, 8 C°/m with cumulative radiation of 22 MJ/m2and 4.6 C°/m with 12 MJ/m2. The gradients produced by a population ofP. richardsoniiwith tips 17 cm from surface were from 5.2 to 3.4 C°/m but showed less correlation with radiation when the wind velocity was above a threshold value. No gradient was produced in tubs of water without plants.

ISSN:0008-4026    

DOI:10.1139/b77-251

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The foliose lichenLobaria oregana(Tuck.) Müll. Arg. is an important nitrogen-fixing component of the canopy epiphyte community in old-growth Douglas fir forests of the Pacific Northwest. This paper presents a non-destructive method for estimating the growth rate (grams per year) forL. oreganathalli of different weights.Photographs were made over a 2-year period of sixin situthalli. From a relationship of the photographic thallus area and weight of these and 31 other thalli, the dry weight of each of the six thalli is estimated through time. A growth rate is computed for each thallus and a relationship between growth rate and initial thallus weight is determined. Growth rate (grams per year) = exp (−0.8581 + 0.8444 (logeinitial weight (grams))). The maximum radial growth rate of lobes ofL. oreganadetermined from the photographs (9.4 mm/year) is comparable with rates for similar species.

ISSN:0008-4026    

DOI:10.1139/b77-252

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The ontogeny of the feminized stamens in a male-sterile tobacco hybrid has been studied. Plant material1Awas derived from an initial cross betweenNicotiana debneyias female andN. tabacumcv. Kupchunos as male. All1Aflowers exhibit stigmatoid anthers at anthesis and are sterile. This teratism is cytoplasmically inherited. In a developmental series of1Afloral buds, it was found that1Astamen primordia diverge relatively early from the normal stamen shape and appear as spatulate organ rudiments lacking differentiation into anther and filament. In1Abuds after carpel fusion and as the normal stigma is differentiating, stamens form a distinctly stigmatoid tip subtended by a short filament bearing the initials of lateral outgrowths. The stigmatoid tip then enlarges to a green, bulbous recurved structure and there is considerable extension growth of the filament. Histological study of developing and mature teratological stamens showed complete absence of sporogenous tissue and also confirmed the true stigmatic nature of the tip region. The results are discussed in relation to regulation of sex determination.

ISSN:0008-4026    

DOI:10.1139/b77-253

出版商:NRC Research Press    

年代:1977

数据来源: NRC