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91.
92.
Edwin W. Salzman 《Biochimica et Biophysica Acta (BBA)/General Subjects》1977,499(1):48-60
The prostaglandin endoperoxide, prostaglandin G2, in platelet-rich plasma may produce reversible platelet aggregation without secretion, irreversible aggregation with secretion of platelet constituents inhibited by indomethacin, or the latter effects despite indomethacin, depending on the concentration of the endoperoxide. Irreversible aggregation and platelet secretion induced by prostaglandin G2 apparently result from the action of ADP, since these responses are inhibited by 2-n-amylthio-5′-AMP (an inhibitor of the actions of ADP on platelets) and they do not occur in heparinized platelet-rich plasma. Prostaglandin G2 lowers the platelet level of cyclic 3′,5′-AMP. Its actions are inhibited by elevation of cyclic AMP levels by prostaglandin E1 or dibutyryl cyclic AMP or adenosine. Like malondialdehyde production induced by thrombin, ADP, or arachidonic acid, prostaglandin G2-induced malondialdehyde production is reduced by dibutyryl cyclic AMP and prosraglandin E1. Platelet activation by prostaglandin G2 is enhanced by the adenylate cyclase inhibitor, 9-(tetrahydro-2-furyl)-adenine.The action of prostaglandin G2 on platelets is more complex then previously reported. 相似文献
93.
94.
Edwin B. Smith 《American journal of botany》1970,57(7):874-880
Pollen competition in mixed pollinations involving a time handicap was studied among the five aneuploid members of section Isopappus of Haplopappus. Foreign pollen was applied to the stigmas of a plant followed after a delay of 0–180 min by domestic pollen. Domestic pollen was prepotent over foreign pollen in all cases, but with increasing delay an increasing percentage of hybrids appeared in the progeny. The time interval required to produce 50% of hybrids in the progeny (at which time the two pollen types were competitively matched in potency) was determined for each cross. The interval is correlated with relatedness, with chromosome number, and with length of the style of the pollen parent. It can be used as an estimate of the potential frequency of hybridization in nature, with all other factors being equal. 相似文献
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97.
Hans J. Bohnert Karl H. J. Gordon Edwin J. Crouse 《Molecular & general genetics : MGG》1980,179(3):539-545
Summary Labelled chloroplast rRNAs from Spinacia oleracea were hybridized to restriction endonuclease digests of chloroplast DNA from Oenothera hookeri and Euglena gracilis, to mitochondrial DNA of Acanthamoeba castellanii, and to DNA of the E. coli rrn B operon in the transducing phage lambda rifd18. The degree of homology is greatest for the 16S rRNA gene. Greater than 90% occurs between the two higher plant genes, 80% homology to the lower plant gene, 60%–70% homology to the bacterial gene, and 20% homology to the mitochondrial gene. The degree of hybridization varied considerably for the 23S and the 5S rRNA genes. Very high homology exists between the two higher plant genes, only about 50% homology for both the Euglena and bacterial genes, and no significant homology for the mitochondrial genes. These results show that any chloroplast (or E. coli) rRNA may be used as a probe to identify rRNA genes in other ctDNAs.Two RNA populations, each enriched for a different ctDNA-encoded mRNA, proved useful in the location of these genes on both higher plant ctDNAs. No significant hybridization was obtained using these probes to the Euglena ctDNA which seems to be too distantly related.Abbreviations Md
megadalton, 106 dalton
- bp, kbp
base pair, kilo base pair
- SSC
Standard saline citrate, 1 times SSC is 0.15M sodium, chloride, 0.015 M trisodium citrate, pH, 6.8
- mtDNA
mitochondrial DNA
- ctDNA
chloroplast DNA
- ctrRNA
chloroplast ribosomal RNA 相似文献
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Edwin R. Price Antonio Brun Verónica Fasulo William H. Karasov Enrique Caviedes-Vidal 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2013,164(2):351-355
Flying vertebrates have been hypothesized to have a high capacity for paracellular absorption of nutrients. This could be due to high permeability of the intestines to nutrient-sized molecules (i.e., in the size range of amino acids and glucose, MW 75–180 Da). We performed intestinal luminal perfusions of an insectivorous bat, Tadarida brasiliensis. Using radio-labeled molecules, we measured the uptake of two nutrients absorbed by paracellular and transporter-mediated mechanisms (l-proline, MW 115 Da, and d-glucose, MW 180 Da) and two carbohydrates that have no mediated transport (l-arabinose, MW 150 Da, and lactulose, MW 342 Da). Absorption of lactulose (0.61 ± 0.06 nmol min? 1 cm? 1) was significantly lower than that of the smaller arabinose (1.09 ± 0.04 nmol min? 1 cm? 1). Glucose absorption was significantly lower than that of proline at both nutrient concentrations (10 mM and 75 mM). Using the absorption of arabinose to estimate the portion of proline absorption that is paracellular, we calculated that 25.1 ± 3.0% to 66.2 ± 7.8% of proline absorption is not transporter-mediated (varying proline from 1 mM to 75 mM). These results confirm our predictions that 1) paracellular absorption is molecule size selective, 2) absorption of proline would be greater than glucose absorption in an insectivore, and 3) paracellular absorption represents a large fraction of total nutrient absorption in bats. 相似文献