摘要:

AbstractIn confirmation of Maximov's earlier results, non‐penetrating (sucrose) and penetrating (dimethylsulfoxide) substances lowered the frost killing temperature from ‐6°C in the control to ‐11° to ‐24°C, depending on the concentration. In contrast to his results, neither glycerol nor CaCl2provided as good or as consistent protection.The addition of 0.05Mmercaptoethanol overcame this protective effect either completely (low concentrations of protectant) or partially (highconcentrations). The effect of the mercaptoethanol occurs during freezing and not during thawing. Since ethanol, without the mercapto‐(SH) group, does not counteract the protective effect, such protection must be related in some way to the sulfhydryl group — perhaps by an effect on the disulfide and sulfhydryl groups o

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1972.tb03611.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractElongating segments from light grown pea (Pisum sativumL. cv. Alaska) and bean (Pbaseolus vulgarisL. cv. Red kidney) stems were incubated in 10‐5Mindoleacetic acid (IAA)‐1‐14C,and ‐5‐3H in the light. Radoactive derivatives, extracted in water, ethanol or ether, and 1Nsodium hydroxide at three different times were chromatographed in three separate systems and the different metabolites identified by their labeling and chromatographic characteristics. Major metabolites included indoleacetyl aspartate, possibly indoleacetyl glucoside, hydroxymethyloxindole, and in bean a further major unidentified compund. Other compounds occurred in lesser amounts. Indole aldehyde was present only in very small quantities. IAA breakdown commenced between 1 and 6 h of incubation, following which IAA decreased and most metabolites increased, though IAA was still present after 24 h. Alkaline hydrolysates contained mainly IAA at a level which changed little between 6

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1972.tb03612.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractCallus cultures derived from stem explants ofTylophora indica(Fam. Asclepiadaceae) show a broad spectrum of tissue differentiation and regenerative potentialities over a wide range of nutrient conditions resulting in the production of roots, shoots, bipolar embryos and plantlets. This has been investigated and interpreted on a histological basis. Studies on the morphogenesis of embryos have shown that only such embryonal cells which were deeply embedded with in the callus parenchyma showed an ontogenic development reminiscent of ovular embryogeny whereas in those organized in the superficial layer of the callus the sequence of embryogeny was entirely different. Free cells growing in agitated liquid media first developed into filamentous structures and eventually, by repeated intercalary divisions, organized into bipolar embryos. Development of accessory embryos through cleavage and budding in the callus, differentiation of amphicribral vascular nodules, and meristematic colonies organized into spheres of parenchyma were also observed. These alternative morphogenetic events probably reflect the biochemical subtleties occurring within the callus as a result of an inadequacy or an imbalance of the various constituents in the culture medium.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1972.tb03613.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractThe effect of gravity compensation by the clinostat on the elongation, weight, and activity of two cell wall‐loosening enzymes (cellulase and β‐1,3‐glucanase) inHelianthus annuushypocotyls was examined. Gravity compensation increases elongation (28.1 %) and weight (18.3 %). The activity of cellulase extracted from the apical sections is raised, but there is no significant effect on β‐1,3‐glucanase. The relationship between gravity compensation, changes in auxin level, and function of these two enzymes in respect to elongation i

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1972.tb03614.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractThe nature of the proteinases which are secreted by barley aleurone layers in response to gibberellic acid was studied by constructing pHvs.activity curves for the hydrolysis of gelatin by incubation media and aleurone layer extracts. The results indicate that the aleurone layers release several different proteinases. The main component is a labile sulphydryl enzyme with an optimum pH of 3.9. The other enzymes include two sulphydryl proteinases with pH optima between pH 5 and 6.5 and a metal‐activated enzyme active at pH 7.0. No differences could be demonstrated between the proteinases released by and retained in the aleurone layer

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1972.tb03615.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractCertain 6‐acylaminopurines have been shown to exhibit activity in several cytokinin bioassays. The active compunds included 6‐N,2′‐O‐dibutyryladenosine 3’:5′‐cyclic monophosphate, but adenosine 3′:5′‐cyclic monophosphate was inactive. The metabolites formed from [2,8‐3H] 6‐benzoylaminopurine by radish seedlings and excised radish cotyledons were investigated. When compared with zeatin, this amide showed considerable stabilityin vivo. Conversion to 6‐benzylaminopurine and its riboside was not detected but slight degradation to adenine was indicated. The principal metabolite

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1972.tb03616.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractCells of the ascomycete Ophiostoma multiannulatum became sensitive to inorganic salts after a heat shock or a treatment with 2,4‐dinitrophenol. The induced sensitivity to chloride and bromide ions could be largely reversed by histidine and certain other imidazole derivatives. No other organic compounds tested except imidazoles possessed this ability. The sensitization is interpreted as a consequence of an injury to cellular membranes, in particular those of the mitochondria, and to an impaired oxidative phosphorylatio

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1972.tb03617.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractUptake of radioactive uracil by light‐dark synchronizedCblorella fuscaShihira and Krauss was studied. For the characterization of the uptake system autospores were used and the following results obtained. Autospores kept in the dark accumulated uracil against a concentration gradient in a process having an observed activation energy of 10 keal/mol in the 10–40°C interval. Addition of glucose to the reaction suspension did not affect the uptake, but, 100 γMdinitrophenol inhibited the process by 90%. Abrupt changes in rate were found upon changing the conditions from light to dark and vice versa, and the rates measured in light were about 2.5 times larger than those found in the dark.Initial rates measured in the dark followed saturation kineties with half maximal rate found at 0.25 γMuracil, and with an apparent maximal rate of 1.7.10‐10mol/10 min . 107cells.The effect of 14 pyrimidines on uptake was tested, and it was found that uracils which were substituted in the 5′ or 5′+ 6′ positions were strongly inhibitory. Of these, thymine and dihydrouracil were tested and shown to inhibit uracil uptake competitively.Initial uptake rates, measured in the dark with 1.0 γMuracil, were recorded at intervals during the 24 h synchronous cycle. The uptake rate per ml culture was constant during the first 9 h, thereafter increasing to reach a peak value at 14 h. This peak was followed by a strong increase from 18 h onwards, this increase being concomitant with the sporulation process, and closely followed

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1972.tb03618.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractProtocorms ofCymbidium(Orchidaceae) were grown on solid or liquid medium with macro‐nutrients according to Wimber (van Raalte 1967) and iron, micro‐nutrients and vitamins according to Nitsch (1968) the medium also contained 2% sucrose. The effects of 1) the auxins; indol‐3yl‐acetic acid (IAA), α‐naphthaleneacetic acid (NAA) and 2,4‐dichlorophenoxyacetic acid (2,4‐D); 2) the cytokinins; 6‐furfurylaminopurine (kinetin) and benzyladenine (BA) and 3) the gibberellin; gibberellic acid (GA) were examined alone or in combinations.IAA had no effect alone. NAA resulted in optimal fresh weight at 10 μMand the protocorms were vigorous, but lighter green than usual. 2,4‐D caused a high weight increase at 1 μM, but the protocorms were abnormal. Higher concentrations of NAA and 2,4‐D inhibited chlorophyll synthesis. On solid medium kinetin (100 μM) induced a growth of many small shoots, but had no effect on the fresh weight. In liquid medium, kinetin promoted a callus formation and fresh weight increase. BA had effects similar to kinetin, but at lower concentrations. GA alone promoted shoot and leaf growth.Combinations of kinetin and NAA resulted in a maximal fresh weight increase at kinetin concentrations one tenth of the NAA concentrations. The optimal growth and the best development occurred at 10 μMNAA and 1 μMkinetin. NAA and kinetin together could limit the shoot and

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1972.tb03619.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractBean plants (Phaseolus vulgarisL. cv. Black Valentine) treated with 2,4‐dichlorophenoxyacetic acid (2,4‐D) and 4‐chlorophenoxyacetic acid (PCPA) absorb and accumulate considerably moreN‐1‐naphthylphthalamic acid (naptalam) than untreated plants. All concentrations of 2,4‐D from 5 x 10‐8to 5 x 10‐4Mwere effective, peak stimulation occurring at 3 x 10‐5M. Plants treated with this concentration took up 186% more naptalam than control plants. It was shown that the leaf area (on a per g dry weight basis) was influenced most by growth regulator treatment. The leaf area of plants treated with 5 x 10‐5M2,4‐D contained 575% more naptalam than the leaf area of untreated plants. The influence of PCPA on naptalam uptake by bean plants was similar to that of 2,4

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1972.tb03620.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY