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101.
R. S. PHILLIPS R. J. M. WILSON G. PASVOLS 《The Journal of eukaryotic microbiology》1978,25(3):394-398
SYNOPSIS. Gametocytes differentiated from ring-stage parasites in microcultures of human blood infected with Plasmodium falciparum. Immature gametocytes could be distinguished morphologically from late asexual trophozoites after ~ 40 h of culture. Differentiation into crescentic forms took several days and the incorporation of [3H]-isoleucine by developing gametocytes was demonstrated. About 1% of red cells contained gametocytes at the maximum densities attained. Differentiation of gametocytes occurred either directly from rings placed in culture or from the progeny of subsequent cycles of schizogony and invasion in vitro. The latter occurrence was confirmed by the development of gametocytes in marker fetal red cells added to cultures, although fetal red cells provide a less favorable environment than those with HbA for growth of the parasites. 相似文献
102.
Alonzo H. Ross Harden M. McConnell 《Biochemical and biophysical research communications》1977,74(4):1318-1325
Band 3, the erythrocyte membrane protein thought to be responsible for anion transport, was purified to near homogeneity using a Concanavalin A affinity column. Band 3 was then combined with egg lecithin, erythrocyte lipid, cholesterol, and glycophorin, the major erythrocyte sialoglycoprotein, to form vesicles capable of rapid sulfate transport. The transport activity was sensitive to prior treatment of the erythrocytes with pyridoxal phosphate-NaBH4, a potent inhibitor of anion transport in these cells. 相似文献
103.
L. R. Guy Valadon Mohamed Osman Rosemary S. Mummery Simone Jerebzoff-Quintin S. Jerebzoff 《Physiologia plantarum》1982,56(2):199-203
An action spectrum for carotenogenesis in V. agaricinum has maxima at 395, 433, 660 and 737 nm. In a previous study it had been shown that a light-minus-dark difference spectrum of a crude extract from V. agaricinum had maxima at 390 and 420 nm, and furthermore a red, far-red interaction suggesting phytochrome involvement has been proposed. All these data suggest that there may be at least two photoreceptor systems operating in the photoinduction process here; one for the near-ultraviolet (UV-A)-mediated carotenogenesis, presumably a novel pigment, and the other for the red, far-red region, most likely phytochrome. 相似文献
104.
Na+-ATPase of high-K+ and low-K+ sheep red cells was examined with respect to the sidedness of Na+ and K+ effects, using inside-out membrane vesicles and very low ATP concentrations (?2 μM). With varying amounts of Na+ in the medium, i.e., at the cytoplasmic surface, Nacyt+, the activation curves show that high-K+ Na+-ATPase has a higher affinity for Nacyt+ compared to low-K+. The apparent affinity for Nacyt+ is also increased by increasing the ATP concentrations in high-K+ but not low-K+. With Nacyt+ present, Na+-ATPase is stimulated by intravesicular Na+, i.e., Na+ at the originally external surface, Naext+, to a greater extent in low-K+ than high-K+. Intravesicular K+ (Kext+) activates Na+-ATPase in high-K+ but not in low-K+ vesicles and extravesicular K+ (Kcyt+) inhibits low-K+ but not high-K+ Na+-ATPase. Thus, the genetic difference between high-K+ and low-K+ is expressed as differences in apparent affinities for both Na+ and K+ and these differences are evident at both cytoplasmic and external membrane surfaces. 相似文献
105.
Protoplasts have been obtained from vegetative thallus of the green seaweed Enteromorpha following enzymic digestion with driselase and pectinase. The viability of purified protoplast fractions was assessed by staining and measurements of O2 uptake and evolution.Abbreviations MES
2-(N-morpholino) ethanesulphonic acid
- TES
N-tris(hydoxymethyl) methyl-2 aminoethanesulphonic acid 相似文献
106.
Paul M. Dewick 《Phytochemistry》1977,16(1):93-97
Feeding experiments have demonstrated that 7,2′-dihydroxy-4′-methoxy-isoflavone-[14C-Me] and -isoflavanone-[14C-Me] are extremely efficient precursors of the phytoalexin demethylhomopterocarpin in Cu2+-treated red clover seedlings. Neither of these compounds, nor demethylhomopterocarpin-[14C-Me], was incorporated into a second pterocarpan phytoalexin, maackiain. 3-Hydroxy-9-methoxypterocarp-6a-ene-[14C-Me] was a poor precursor of both pterocarpans. A biosynthetic pathway to demethylhomopterocarpin via 2′-hydroxylation of formononetin (7-hydroxy-4′-methoxyisoflavone) and subsequent reduction to the isoflavanone is proposed. The conversion of this isoflavanone into the pterocarpan may involve the corresponding isoflavanol and a carbonium ion intermediate. The branch-point to maackiain is probably at the formononetin stage. The presence of two coumestans, 9-O-methylcoumestrol and medicagol, previously unreported in red clover, is demonstrated. Biosynthetic implications are discussed. 相似文献
107.
RNase activity from Chlorella was partially purified. Two RNase activities were demonstrated, one soluble and the other ribosomal. The effects on ribonuclease activity of variations in pH and temperature, and of Mg2+, Na+, and mononucleotides were examined. The RNase activities (phosphodiesterases EC 3.1.4.23) were both endonucleolytic, releasing oligonucleotides, and cyclic nucleotide intermediates, but exhibited different specificities in releasing mononucleotides from RNA. The ribosomal activity released 3′-GMP, and after prolonged incubation 3′-UMP, but the soluble activity released 3′-GMP, 3′-AMP and 3′-UMP. Neither ofthe RNase preparations hydrolysed DNA, nor released 5′-nucleotides from RNA. Increased ribosomal RNase activity was related to dissociation of ribosomes, and latency of ribosomal RNase activity was demonstrated. The possible in vivo distribution of RNases is discussed. 相似文献
108.
A web-like reticulum underlying the human erythrocyte membrane was studied at a resolution of 5–10 nm by means of a scanning electron microscope. The network was visualized in isolated membranes (ghosts) torn open to reveal their interior space and in residues derived from ghosts extracted with Triton X-100. It formed a continuous (rather than patchy) cover over the entire cytoplasmic surface, except where lifted off or torn away. Filaments (5–40 nm in diameter), annular figures (40–60 nm in diameter), and nodes (30–100 nm in diameter) were prominent in different networks. The dimensions of the filaments and the interstices in the reticulum varied with conditions, suggesting that the network has elastic properties. This reticulum is probably related to the erythrocyte membrane proteins spectrin and actin. 相似文献
109.
Gymnodimium breve Davis, an unarmored marine dinoflagellate has a cell covering (theca) composed of four membranes. The inner two membranes represent a vesicular layer and in tangential section, the theca appears composed of polygonal areas. Unusual threat ridges are located in the cingular region between the epi- and hypocone. This osmotically sensitive species is extremely vesiculate with dispersed areas of cytoplasm containing typical eukaryotic organelles as well as other organelles found only in dinoflagellates. The non-vesiculated cytoplasm is continuous in serial sections. The chloroplasts can contain either quasi-radial or parallel lamellae typically consisting of three thylakoids each. The pyrenoid is multiple-stalked and lacks a starch cap. The dinophycean pusule is simple and similar to those found in several unarmored marine species. The nucleus is typically dinophycean but the chromosomes appear to lack nonfibrillar material. 相似文献
110.
Toshiharu Hase Sadao Wakabayashi Hiroshi Matsubara K.Krishna Rao David O. Hall Herbert Widmer Jurg Gysi Herbert Zuber 《Phytochemistry》1978,17(11):1863-1867
Ferredoxin was purified from the thermophilic blue-green alga, Mastigocladuslaminosus. The physicochemical properties of this ferredoxin are similar to those of other [2Fe-2S] plant ferredoxins except for its unusual thermal stability. The primary structure of the protein was determined and consists of 98 amino acid residues, 5 of which are cysteines. The positions of 4 cysteines which bind the iron atoms of the active centre are identical to those in other ferredoxins. The primary structure of the ferredoxin does not reveal any special features to account for its high thermal stability. 相似文献