摘要:

AbstractSexual reproduction of many dermatophytes is easily induced in complex media such as soil plus keratin. InArthroderma benhamiaethis process could be initiated also in synthetic agar media. A number of carbon sources (glucose, fructose, galactose, mannose, maltose, lactose, sorbose, sucrose) had about the same stimulatory effect on reproduction, while xylose was inhibitory. Organic sulphur was not crucial for the process in contrast to the nitrogen supply. The nitrogen sources could be divided into four groups; I. very stimulatory (arginine, citrulline, isoleucine, leucine, ornithine, phenylalanine, proline, valine, glutathione); II. stimulatory (alanine, asparagine, lysine, serine); III. slightly stimulatory (aspartic acid, cysteine, glutamic acid, glycine, histidine, urea, NH4Cl, NH4‐tartrate); IV. inhibitory (hydroxyproline, methionine, threonine, tryptophan). Synergistic effects were shown between some amino acids. Generally a combination between 5 g/l glucose and 300–400 mg/l nitrogen induced the largest number of cleistothecia, regardless of the nitrogen source used. The level varied between the sources, however. A C/N ratio of about 10 was optimal while a value above 20 gave no cleistothecia. The optimal temperature for the process was 30°C. Sexual reproduction occurred between pH 4.4 and 8.0 (final values). However, at a final pH above 7.2 the number of ascospores/cleistothecium was red

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03698.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractIsocitrate lyase (ICL) ofChlorellawas induced with acetate, and induction kinetics followed in autospores and 6 h old cells of a synchronous culture.The enzyme could not be induced in illuminated cells. With both cell types 1.2 mMacetate was the optimal inducer concentration. Freeze‐thawed cells and acetone powders were used for measurement of activity. With the former the time course of increase in activity was different at the two cell ages. With 6 h old cells the activity fluctuated: There was first a period of increase, then one with decrease and again one of increase. No such variation was found with freee‐thawed autospores or with acetone powders of both cell stages. Darkening 6 h old cells for different periods of time before induction reduced the peak of activity, leaving the rate of the third phase unchanged. Illumination of darkened cells before induction increased the peak. Increasing the duration of both treatments increased their respective effects.Acetone extracts taken at different times after start of induction inhibited the ICL activity of a test preparation. The inhibition decreased concurrently with the variation in the ICL activity‐found‐when freee‐thawed cells were used in the enzyme assay.The inducibility, taken as the rate of the third phase, was measured at different times during the 24 h synchronous cycle. Using three different acetate concentrations and both methods of cell preparation, we found that the inducibility was constant for 17 h whereafter it increased rapidly to a fi

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03699.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractAn easy and rapid method for the purification of a bacteriolytic endopeptidase produced byMyxococcus virescensis described. The bacteria were grown in casitone media and the cells were sedimented by centrifugation. About 1.2 g of montmorillonite were added per liter of cell‐free culture solution. The clay was sedimented by centrifugation and the enzyme was then eluted by 0.05MNa‐phosphate buffer pH 6.0, containing 0.4MNaCl. The enzyme was diluted with water and chromatographed on carboxymethyl‐cellulose columns.The purified enzyme liberated free amino groups but no reducing sugars or N‐acetylhexosamines when acting on purified N‐acetylated cell walls ofMicrococcus lysodeikticus. Analysis of N‐ and C‐terminal amino acids in the digestion products showed that the enzyme had liberated about 110 nmoles of lysine ε‐amino groups and 60 nmoles of alanine carboxyl groups per mg of cell wall. When it acted on a bisdisaccharide pentapeptide dimer isolated from M. lysodeikticus cell walls, it cleaved about 30% of the alanyl‐lysine linkages. Consequently the enzyme was an alanyl‐lysine endopeptidase. It had no muramyl‐al

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03700.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractEmbryogenic callus was induced by culturing explants of pumpkin hypocotyls on Murashige‐Skoog‐medium with the addition of 3% glucose and one of the following growth substances (or combinations of them): β‐indolylbutyric acid, 2,4‐dichlorophenoxyacetic acid, β‐indolylacetic acid, α‐naphthyl‐acetic acid, adenine (natural), kinetin, autoclaved water‐melon sap and yeast extract (Difco). A large number of embryoids and adventive buds were produced. These were able to develop to normal plants.The 17 strains of embryogenic tissue obtained have maintained their embryogenic characteristics for more than 3 years. The induction of embryogenic callus in pumpkin seems to be strongly dependent on the genetic constitution of eac

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03701.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractEtiolated 6‐day‐old wheat (Triticum aestivumL. cv. Chris) seedlings were subjected to osmotic stress by an application of polyethylene glycol 12 h prior to the exposure to a continuous 72‐h light period. The water potential of the primary leaf of stressed seedlings was between –9 and –14 bars throughout the light period.Stress impaired seedling growth, leaf unfolding, and the increase in leaf area. The imposed osmotic stress reduced total chlorophyll accumulation, particularly after 9 h light, suggesting that this is the approximate time period for the depletion of the protochlorophyll(ide) pool and the pool of an essential protochlorophyll(ide) precursor. The chlorophylla/bratio of extracts from stressed and non‐stressed plants was the same during the 72‐h greening period. Water deficit stress impaired carotenoid accumulation sooner than the impairment of chlorophyll production suggesting either a smaller carotenoid pool size of precursors or that the metabolic pathway of carotenoid synthesis was more sensitive to stress. Shifts from the usual plastid pigment absorbance maxima were not observed in

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03702.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe exposure of red beet root tissue to ultraviolet (254 nm) at 2 × 106erg × cm−2× min−1(0.2 J × cm−2× min−1) causes release of betacyanin after a 20 minute induction period. Ultraviolet‐photolysis is temperature‐sensitive having a thermal threshold at about 10°C. Reduction in pigment release was effected by chlorides of Mg, Ca and Sr, but not by Li, Na or K. This effect was marked but not complete, even at 40 mMconcentration.It is concluded that photolysis is indirect, and involves a lytic factor, possibly an oxidant, derived from an original phot

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03703.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractAn acid ether‐soluble, strongly growth‐stimulating substance revealed by the Avena coleoptile straight‐growth test in methanol extracts from bean seedlings (Phaseolus vulgarisL.) was identified as indol‐3yl‐aspartic acid (IAAsp). Points of agreement between synthetic IAAsp and the investigated growth stimulator were indicated by chromatographic behavior, elution volume in gel filtration, mobility in paper electrophoresis, “colour reaction” with DMCA reagent, ability to form indol‐3yl‐acetic acid (IAA) and aspartic acid after hydrolysis and, finally, biological activity in the Avena test. Furthermore, some experiments demonstrated the occurrence of an inhibitor in extracts from light‐grown tissue. This masked the stimulation of IAAsp in the Avena test when the extracts had been chromatographed in isopropanol: NH3:H2O. A comparison of the levels of IAAsp between green and etiolated tissue did not reveal any distinct difference, demonstrating that the IAA conjugate IAAsp does not participate in the regulation of the

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03704.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractChanges in the net photosynthesis of leaflets ofPisum sativumL. (cv. Onward) were found to reflect closely the pattern of assimilate demand in subtended fruit during development. An early peak in leaflet photosynthesis corresponded with the rapid elongation of the fruit; a second peak with the inflation of the pod and initiation of seed growth. However, where the subtended fruit was removed at anthesis, the pattern of fluctuation in leaflet photosynthesis was altered, while leaflets at vegetative nodes maintained a lower photosynthetic rate which fluctuated little. The pattern of net photosynthesis in the fruit appears to reflect the high respiration rates associated with pod elongation and seed growth. This closely coupled system, where fruit assimilate demand modulates the photosynthesis of adjacent leaflets, provides a scope for study of source‐sink relationships with the minimum of experimental manipulatio

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03705.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractConcentrations of free and bound amino acids were determined in 1) the mycorrhizal fungusBoletus variegatusFr. 2) nonmycorrhizal root systems of aseptically grownPinus sylvestrisL. seedlings, and 3) mycorrhizal root systems of seedlings developed aseptically using the two symbionts.Arginine (total) was the major amino acid constituent in the mycelium of B. variegatus (18%–22%) during the exponential phase of growth. While 59%–86% of the available arginine was bound during the acceleration phase of growth, in the logarithmic phase 63%–75% was in the free pool. There were differences in the proportions between the individual amino acids in the bound fraction at different stages of growth suggesting production of diverse proteins.Twenty per cent of the amino acid content of uninfected P. sylvestris root systems was arginine. Infection of the root systems by the fungal symbiont did not result in an increase but a slight decrease in the free arginine content of the composite structure. Almost all other amino acids in the free pool were found in higher concentrations in the mycorrhizal root system. It is suggested that arginine synthesis in B. variegatus is repressed by the arginine available in the host. The mycorrhizal fungus possibly metabolizes the host arginine pool ultimately resulting in more efficient protein synthesis in both the par

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03706.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractLanolin containing3H‐IAA was applied to apical cut ends of stem segments and decapitated plants ofCordyline terminalis, a monocotyledon possessing true secondary growth. Distribution of extracted label showed that: 1) in horizontal stems up to 7 times as much label accumulates in the lower surface compared to the upper surface, and this ratio increases with distance from the cut apical surface; 2) in upright stems most label (62%) occurs in the cambial and cortical regions, external to the primary and secondary vascular tissues; and 3) in upright stems having the cambium and cortical regions removed by a girdle, label accumulates above the girdle (c. 10 times greater than the control). These data are in accord with a theory of branch dimorphism derived from morphological studies, which suggested that high auxin levels initiate and maintain rhizomes and low levels initiate leafy shoot

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03707.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY