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1.
Chloroplast Biogenesis 60 : Conversion of Divinyl Protochlorophyllide to Monovinyl Protochlorophyllide in Green(ing) Barley, a Dark Monovinyl/Light Divinyl Plant Species 总被引:3,自引:2,他引:1 下载免费PDF全文
In higher plants, most of the chlorophyll a is formed via the divinyl and monovinyl chlorophyll monocarboxylic biosynthetic routes. These two routes are strongly interconnected prior to protochlorophyllide formation in barley (Hordeum vulgare L. cv Morex), a dark monovinyl-light divinyl plant species, but not in cucumber (Cucumis sativus L. cv Beit Alpha MR), a dark divinyl-light divinyl plant species (BC Tripathy, CA Rebeiz, 1986 J Biol Chem 261: 13556-13564). It is shown that in dark monovinyl-light divinyl plant species such as barley, the divinyl and monovinyl monocarboxylic routes become interconnected at the level of protochlorophyllide during transition from the divinyl to the monovinyl protochlorophyllide biosynthetic mode. In cucumber, a dark divinyl-light divinyl plant species, in which the monovinyl monocarboxylic biosynthetic route becomes preponderant only after an abnormally long sojourn in darkness, the conversion of divinyl to monovinyl protochlorophyllide does not take place on the barley time-scale of incubation. 相似文献
2.
The massive conversion of delta-aminolevulinic acid (ALA) to protochlorophyllide (Pchlide) and the massive conversion of chlorophyllide a (Chlide a) to chlorophyll a (Chl a) are two essential conditions for the ALA-dependent assembly of photosynthetic membranes in vitro. In this work, we describe the development of a cell-free system capable of the forementioned biosynthetic activities at rates higher than in vivo, for the first 2 h of dark-incubation. The cell-free system consisted of (1) etiochloroplasts prepared from kinetin and gibberellic-acid-pretreated cucumber cotyledons, and (2) cofactors and additives described elsewhere and which are needed for the massive conversion of ALA to Pchlide, (3) high concentrations of ATP, MgCl(2), and an isoprenol alcohol such as phytol, were required for the massive conversion of Chlide a to Chl a. An absolute and novel requirement of Mg(2+) for the conversion of Chlide a to Chl a was also demonstrated. In addition to the role of phytol as a substrate for the conversion of Chlide a to Chl a, the data suggested that this alcohol may also be involved in the regulation of the reactions between ALA and Pchlide. It is proposed that during greening, the conversion of Chlide a to Chl a may follow different biosynthetic rates, having different substrate and cofactor requirements, depending on the stage of plastid development. 相似文献
3.
Hardies SC; Martin SL; Voliva CF; Hutchison CA d; Edgell MH 《Molecular biology and evolution》1986,3(2):109-125
4.
A major difference between the divergence patterns within the lines-1 families in mice and voles 总被引:3,自引:0,他引:3
Vanlerberghe F; Bonhomme F; Hutchison CA d; Edgell MH 《Molecular biology and evolution》1993,10(4):719-731
L1 retroposons are represented in mice by subfamilies of interspersed
sequences of varied abundance. Previous analyses have indicated that
subfamilies are generated by duplicative transposition of a small number of
members of the L1 family, the progeny of which then become a major
component of the murine L1 population, and are not due to any active
processes generating homology within preexisting groups of elements in a
particular species. In mice, more than a third of the L1 elements belong to
a clade that became active approximately 5 Mya and whose elements are >
or = 95% identical. We have collected sequence information from 13 L1
elements isolated from two species of voles (Rodentia: Microtinae: Microtus
and Arvicola) and have found that divergence within the vole L1 population
is quite different from that in mice, in that there is no abundant
subfamily of homologous elements. Individual L1 elements from voles are
very divergent from one another and belong to a clade that began a period
of elevated duplicative transposition approximately 13 Mya. Sequence
analyses of portions of these divergent L1 elements (approximately 250 bp
each) gave no evidence for concerted evolution having acted on the vole L1
elements since the split of the two vole lineages approximately 3.5 Mya;
that is, the observed interspecific divergence (6.7%-24.7%) is not larger
than the intraspecific divergence (7.9%-27.2%), and phylogenetic analyses
showed no clustering into Arvicola and Microtus clades.
相似文献
5.
Molecular phylogeny and divergence times of drosophilid species 总被引:32,自引:15,他引:17
The phylogenetic relationships and divergence times of 39 drosophilid
species were studied by using the coding region of the Adh gene. Four
genera--Scaptodrosophila, Zaprionus, Drosophila, and Scaptomyza (from
Hawaii)--and three Drosophila subgenera--Drosophila, Engiscaptomyza, and
Sophophora--were included. After conducting statistical analyses of the
nucleotide sequences of the Adh, Adhr (Adh-related gene), and nuclear rRNA
genes and a 905-bp segment of mitochondrial DNA, we used Scaptodrosophila
as the outgroup. The phylogenetic tree obtained showed that the first major
division of drosophilid species occurs between subgenus Sophophora (genus
Drosophila) and the group including subgenera Drosophila and Engiscaptomyza
plus the genera Zaprionus and Scaptomyza. Subgenus Sophophora is then
divided into D. willistoni and the clade of D. obscura and D. melanogaster
species groups. In the other major drosophilid group, Zaprionus first
separates from the other species, and then D. immigrans leaves the
remaining group of species. This remaining group then splits into the D.
repleta group and the Hawaiian drosophilid cluster (Hawaiian Drosophila,
Engiscaptomyza, and Scaptomyza). Engiscaptomyza and Scaptomyza are tightly
clustered. Each of the D. repleta, D. obscura, and D. melanogaster groups
is monophyletic. The splitting of subgenera Drosophila and Sophophora
apparently occurred about 40 Mya, whereas the D. repleta group and the
Hawaiian drosophilid cluster separated about 32 Mya. By contrast, the
splitting of Engiscaptomyza and Scaptomyza occurred only about 11 Mya,
suggesting that Scaptomyza experienced a rapid morphological evolution. The
D. obscura and D. melanogaster groups apparently diverged about 25 Mya.
Many of the D. repleta group species studied here have two functional Adh
genes (Adh-1 and Adh-2), and these duplicated genes can be explained by two
duplication events.
相似文献
6.
C.A. Rebeiz A. Montazer-Zouhoor H.J. Hopen S.M. Wu 《Enzyme and microbial technology》1984,6(9):390-396
A new approach to the design of conceptually and phenomenologically new herbicides is described. It involves the joint utilization of tetrapyrrole precursors, such as δ-aminolaevulinic acid (a biodegradable amino acid) and activators of the chlorophyll biosynthetic pathway, such as 2,2′-dipyridyl, in order to induce treated plants to biosynthesize and accumulate massive amounts of tetrapyrrole intermediates of the chlorophyll biosynthetic pathway in the dark (i.e. at night). During the subsequent light period (daylight) the accumulated tetrapyrroles act as potent photodynamic sensitiziers, which in turn result in the death of susceptible plants in a matter of hours. We have therefore proposed to name herbicides that act via this mechanism as photodynamic herbicides, or more pictorially as laser herbicides. From a limited survey of agricultural plant and weed species it appears that photodynamic herbicides exhibit a very pronounced organ, age and species-dependent selectivity. For example, dicotyledonous weeds such as mustard, red-root pigweed, common purslane and lambsquarter are very susceptible while monocotyledonous plants such as corn, wheat, barley and oats are not. The biochemical basis of this selectivity seems to lie, among other things, in the rates of tetrapyrrole turnover and in a differential enhancement by the applied chemicals of the monovinyl and divinyl tetrapyrrole biosynthetic pathways in the various species. A survey of various groups of chemicals (herbicides and other selected biochemicals) that are likely to exhibit photodynamic herbicidal properties is currently under investigation. 相似文献
7.
Chloroplast Biogenesis: XXIV. Intrachloroplastic Localization of the Biosynthesis and Accumulation of Protoporphyrin IX, Magnesium-Protoporphyrin Monoester, and Longer Wavelength Metalloporphyrins during Greening 下载免费PDF全文
The intraplastidic localization of the endogenous metabolic pools from protoporphyrin to protochlorophyll was determined in Cucumis sativus. The endogenous protoporphyrin, Mg-protoporphyrin monoester + longer wavelength metalloporphyrins, protochlorophyllide and protochlorophyllide ester were membrane-bound. Protoporphyrin was synthesized in the stroma and subsequently became associated with the membranes. The membrane-associated protoporphyrin was then converted into Mg-protoporphyrin monoester + longer wavelength metalloporphyrins by membrane-bound enzymes. Although lysed plastids were capable of converting exogenous δ-aminolevulinic acid to protochlorophyllide, the net synthesis of protochlorophyllide from exogenous δ-aminolevulinic acid was lost upon segregating the lysed plastids into stromal and membrane fractions and then recombining the stromal and membrane fraction prior to incubation. The segregated membrane fraction was still capable of converting protoporphyrin into Mg-protoporphyrin monoester + longer wavelength metalloporphyrins in the presence or absence of the stromal fraction. These results indicated that although the reactions from protoporphyrin to Mg-protoporphyrin monoester and longer wavelength metalloporphyrins could survive a considerable degree of plastid disruption, the reactions from Mg-protoporphyrin monoester and longer wavelength metalloporphyrins to protochlorophyllide were more sensitive to structural disorganization. 相似文献
8.
V P Shedbalkar I M Ioannides C A Rebeiz 《The Journal of biological chemistry》1991,266(26):17151-17157
The occurrence of protochlorophyllide b and protochlorophyllide b phytyl ester in green plants is described. The chemical structure of protochlorophyllide b phytyl ester was established by proton nuclear magnetic resonance, fast atom bombardment mass spectroscopic analysis, and chemical derivatization coupled to electronic spectroscopic analysis. The macrocycles of protochlorophyll(ide) b are identical to those of conventional protochlorophyll(ide) except for the presence of a formyl group instead of a methyl group at position 3 of the macrocycles. They differ from chlorophyll(ide) b by the presence of an oxidized double bond at positions 7 and 8 of the macrocycles. The trivial name protochlorophyll(ide) b is proposed to differentiate these two tetrapyrroles from conventional protochlorophyll(ide), which in turn will be referred to as protochlorophyll(ide) a. Protochlorophyll(ide) b appears to be widely distributed in green plants. Its molar extinction coefficients in 80% acetone and diethyl ether are reported. The impact of this discovery on the heterogeneity of the chlorophyll a and b biosynthetic pathways is discussed. 相似文献
9.
Sulfate reduction and S-oxidation in a moorland pool sediment 总被引:3,自引:2,他引:1
In an oligotrophic moorland pool in The Netherlands, S cycling near the sediment/water boundary was investigated by measuring (1) SO4
2– reduction rates in the sediment, (2) depletion of SO4
2– in the overlying water column and (3) release of35S from the sediment into the water column. Two locations differing in sediment type (highly organic and sandy) were compared, with respect to reduction rates and depletion of SO4
2– in the overlying water.Sulfate reduction rates in sediments of an oligotrophic moorland pool were estimated by diagenetic modelling and whole core35SO4
2– injection. Rates of SO4
2– consumption in the overlying water were estimated by changes in SO4
2– concentration over time in in situ enclosures. Reduction rates ranged from 0.27–11.2 mmol m–2 d–1. Rates of SO4
2– uptake from the enclosed water column varied from –0.5, –0.3 mmol m–2 d–1 (November) to 0.43–1.81 mmol m–2 d–1 (July, August and April). Maximum rates of oxidation to SO4
2– in July 1990 estimated by combination of SO4
2– reduction rates and rates of in situ SO4
2– uptake in the enclosed water column were 10.3 and 10.5 mmol m–2 d–1 at an organic rich and at a sandy site respectively.Experiments with35S2– and35SO4
2– tracer suggested (1) a rapid formation of organically bound S from dissimilatory reduced SO4
2– and (2) the presence of mainly non SO4
2–-S derived from reduced S transported from the sediment into the overlying water. A35S2– tracer experiment showed that about 7% of35S2– injected at 1 cm depth in a sediment core was recovered in the overlying water column.Sulfate reduction rates in sediments with higher volumetric mass fraction of organic matter did not significantly differ from those in sediments with a lower mass fraction of organic matter.Corresponding author 相似文献
10.
Chloroplast Biogenesis 34: SPECTROFLUOROMETRIC CHARACTERIZATION IN SITU OF THE PROTOCHLOROPHYLL SPECIES IN ETIOLATED TISSUES OF HIGHER PLANTS 下载免费PDF全文
The fluorescence emission and excitation properties of protochlorophyll in etiolated cucumber (Cucumis sativus L.) cotyledons and primary bean (var. Red Kidney) leaves were characterized at 77 K. Contrary to previous studies, it appears that the short-wavelength protochlorophyll emission band consists of four fluorescent components, instead of only one nonphototransformable protochlorophyll. It was demonstrated that etiolated cucumber cotyledons synthesize and accumulate nontransformable protochlorophyll (E440, F630) as well as short-wavelength phototransformable protochlorophyll (E433, F633), (E444, F636), and (E445, F640). Long-wavelength phototransformable protochlorophyll (E450, F657) is also formed. In this context, E refers to the Soret excitation maxima and F refers to the red emission maxima of the protochlorophylls. 相似文献