摘要:

Books reviewed in this article:PLANT LIFE IN ANAEROBIC ENVIRONMENTS. Editer by DonaldD. Hookand R. M. M. Crawford

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1979.tb00069.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractRecent advances in the insertion, uptake and expression of exocellular DNA in plant protoplasts are reviewed. A comparison is made between plant and mammalian cell systems, in which exogenous DNA is processed during metabolism.

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1979.tb00070.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractRadioactive dihydrofusicoccin (3H‐FC), known to have the same biological activity as fusicoccin on plant tissues, has a specific affinityin vitrofor sites localized on subcellular, postmitochondrial particles from maize coleoptiles. The analysis of the kinetics of dihydrofusicoccin binding suggests the presence of two classes of sites, one class with a high affinity and a second class with a lower affinity. The high affinity class of sites has a dissociation constant (Kd) of 1.2 × 10−9mol dm−3, and an apparent pH optimum at 5.5. Binding is antagonized by non‐physiological pH, high temperatures and protein‐reactive substances like HgCl2, p‐chloromercuribenzensulphonate and glutaraldehyde. Treatment of dihydrofusicoccin‐bound membrane preparations with Triton X‐100 leads to the solubilization of a protein fraction associated with dihydrofusicoccin. These data suggest a protein nature for th

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1979.tb00071.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractLight and fluorescence microscopy studies indicated that chlorophyll was absent from the guard cells of the lady slipper orchids,Paphiopedilum insigne(Wall.) Pfitz,P. insigne(hybrid),P. venustum(Wall.) Pfitz andP. harrisseanumHort. In the guard cells ofP. aureum hyeanumHort., however, very slight red fluorescence suggested that chlorophyll and hence chloroplasts were present.Ultrastructural studies of the lower epidermis ofP. insigne(hybrid) confirmed the absence of chloroplasts in guard and epidermal cells although plastids of an unusual structure were found in these cells. In fully developed epidermal cells the plastids contained large amounts of a fibrous, possibly proteinaceous substance, spherical, lightly staining vesicles and an electron‐dense material located in reticulate and non‐reticulate regions. Additionally, latticed crystalline inclusions and plasto‐globuli were occasionally observed in the epidermal cell plastids. In plastids of fully developed guard cells the fibrous material, starch and plastoglobuli were present.From the earliest stages of development of the epidermal tissue starch was present in both epidermal cell and guard cell plastids. At maturity, however, starch had accumulated to greater levels in the guard cell plastids and had entirely disappeared in the epidermal cell plastids. In differentiating epidermal tissue, plasmodesmata were found between neighbouring epidermal cells and between guard and epidermal cells. At maturity, plasmodesmata between guard and epidermal cells were not observed. Mitochondria were particularly abundant in guard cells. Large oil drops developed in guard and epidermal cells, being especially abundant in the former at maturity.Our results confirm the observations of Nelson&Mayo (1975) that certain lady slipper orchids possess functional stomata the guard cells of which do not contain chlorop

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1979.tb00072.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractIt is widely held that the albumins of pea seeds are mainly enzyme proteins. In the present study ofPisum sativumcv. Greenfeast, certain major polypeptides confined to the albumin fraction from the cotyledons were shown to be degradedin vivofollowing germination, thus functioning as a reserve of amino nitrogen and carbon skeletons. A general definition of seed storage proteins is proposed, to encompass any protein present in major quantity in the seed which is degraded following imbibition, and for which no other function may be demonstrated.

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1979.tb00073.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractConditions are described for measuring the starch content of plant tissues or extracts as glucose over the range from 10−7mol to 10−14mol. The method is based on the hydrolysis of gelatinized starch by amyloglucosidase; the glucose released is measured by reduction of NADP+by coupled enzymic reactions.The NADPH is determined directly either spectrophotometrically or fluorimetrically, or after enzymic amplification. Amyloglucosidases were tested for contaminating enzymes which might degrade glucans other than starch, and a commercial preparation fromRhizopus niveuswas found to be suitable for use without pretreatments. Glucose present in tissues and extracts may be measured and subtracted from starch values using appropriate blanks, or first destroyed by dilute alkali and heat. Addition of α‐amylase to amyloglucosidase during starch hydrolysis was not found to increase percentage hydrolysis from the normal range of 86–99% from starches of different sources.The procedures described are rapid and several orders of magnitude more sensitive than current methods, and can be used to measure the starch content of sing

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1979.tb00074.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractIn this revised formulation of guard cell mechanics, the material properties of the walls are re‐examined. The observed elastic anisotropy of guard cell walls can be explained by non‐random orientation of the cellulose micellae in the unstrained state. This micellar network is assumed to be loosely embedded in the wall matrix causing a two phase elongation process. In the first phase, the micellar network is ‘loose’ resulting in the walls behaving as an isotropic polymer when stretched. As the volume of the cell expands beyond some threshold, the network becomes ‘tightened’ and a second phase of elongation is initiated. During this anisotropic phase of cell expansion, wall elasticity reflectes changes in the orientation of the network to reduce its load.Using the above theoretical analysis, a turgor‐pressure versus lumen volume relationship is simulated forVicia faba. The relationship between aperture and water potential for this species is also established. The simulated results agree with the experimental evidence reported forVicia faba. The estimated shear modulus of elasticity for guard cell walls is 2 MPa (20 bars) which is well within the limits of reported values for other biolo

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1979.tb00075.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractThe acid‐base balance during NO3−assimilation inHydrodictyon africanumhas been investigated during growth from (1) an analysis of the elemental composition of the cells, (2) the alkalinity of the ash and (3) the net H+changes in the medium during growth. These investigations agree in showing that some 0.25 excess organic negative charges are generated per N assimilation from No3−as N‐source and C02 as C‐source; the excess OH−(0.75 OH−per NO3−assimilated) appears in the medium. Approximately half of the excess organic negative charge is attributable to cell wall uronates; the remainder is intracellular. All of the excess OH−appearing in the medium must have crossed the plasmalemma (as net downhill H+influx or OH−efflux).Previous work has shown that the value of ψco is more negative than ψK+during NO3−assimilation, suggesting that the active electrogenic H+extrusion pump is still operative despite the net downhill H+influx. The interpretation of this in terms of H+−NO3−symport which causes the entry of more H+than is consumed in NO3−metabolism, with extrusion of the excess H+viathe active, electrogenic H+pump, was tested by measuring short‐term H+influx upon addition of NO−3. A net H+influx occursbeforeNOa assimilation (as indicated by additional O2evolution in the light) has commenced, suggesting amechanisticrelation of H+and NO3−influxes. This is consistent with the interpretation suggested above. Determinations of cytoplasmic pH showed no significant effect of NO3−assimilation, suggesting that cytoplasmic pH changes sufficient to change the ‘pH‐regulating’ H+fluxes are smaller than the er

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1979.tb00076.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractA scheme to account for the phytochrome responses of dark grown and green plants is presented. In contrast to some other models (e.g. Smith, 1970; Schäfer, 1975) it is proposed that both Pfr and the photoconversions of phytochrome are effectors of phytochrome action and interact to promote the observed responses. Under conditions where Ptot is not strongly wavelength dependent (e.g. with short pulses of light and in plants grown for prolonged periods in the light), responses will be predominantly related to Pfr concentration. Where Ptot is the major wavelength dependent variable (e.g. in the ‘high irradiance reaction’ of etiolated seedlings) it is proposed that the photoconversion process itself predominates in controlling the ultimate response. Some responses predicted by the scheme are compared with relevant published

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1979.tb00077.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractCercosporin, excited by incandescent light in the presence of oxygen, induced a loss of ions from the plant tissues tested. Silymarin, BHA (2(3)‐tert‐butyl‐4‐hydroxyanisole) and EDTA were effective in lowering the activity of cercosporin. Circumstantial evidence suggests that the toxic effect may be mediated by the singlet oxygen and free radical formation which induces a lipoperoxidative degradation of the polyunsaturated fatty acids of cell me

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1979.tb00078.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY