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31.
Robin A. Woods Darlene G. Roberts Theodore Friedman Douglas Jolly David Filpula 《Molecular & general genetics : MGG》1983,191(3):407-412
Summary Yeast mutants lacking activity of the enzyme hypoxanthine: guanine phosphoribosyltransferase (H:GPRT) have been isolated by selecting for resistance to 8-azaguanine in a strain carrying the wild type allele, ade4
+ of the gene coding for amidophosphoribosyltransferase (PRPPAT), the first enzyme of de novo purine synthesis. The mutants excrete purines and are cross-resistant to 8-azaadenine. They are recessive and represent a single complementation group, designated hpt1. Ade4-su, a prototrophic allele of ade4 with reduced activity of PRPPAT, is epistatic to hpt1, suppressing purine excretion and resistance to azaadenine but not resistance to azaguanine. The genotype ade2 hpt1 does not respond to hypoxanthine. Hpt1 complements and is not closely linked to the purine excreting mutants pur1 to pur5. Hpt1 and pur6, a regulatory mutant of PRPPAT, are also unlinked but do not complement, suggesting a protein-protein interaction between H:G-PRT and PRPPAT. Mycophenolic acid (MPA), an inhibitor of de novo guanine nucleotide synthesis, inhibits the growth of hpt1 and hpt1
+. Xanthine allows both genotypes to grow in the presence of MPA whereas guanine only allows growth of hpt1
+. Activity of A-PRT, X-PRT and H:G-PRT is present in hpt
+. Hpt1 lacks activity of H:G-PRT but has normal A-PRT and X-PRT. 相似文献
32.
Robin Huw Crompton 《Primates; journal of primatology》1983,24(2):241-259
The locomotor behaviour ofGalago senegalensis andG. crassicaudatus (Primates: Lorisidae) was quantified in an 11-month field study in the Northern Transvaal of South Africa. This paper assesses
the distinction between the behaviour of adults, and that of infants at the age when they first began foraging independently,
taking into account seasonal variations in adult behaviour. Infants of both species differ significantly from adults in the
types of locomotion they use, postures, activity, support use, height of observation and tree use. While all these factors
are inter-connected, it is concluded that infants exploit a quantitatively different part of the arboreal habitat from adults,
because of factors such as locomotor maturation and gross body size. Dietary differences are also possible but the present
study cannot establish or deny this possibility. 相似文献
33.
Robin Arthur Woods 《Molecular & general genetics : MGG》1969,105(4):314-316
Summary Confirmation that the ad-2 locus of yeast controls the carboxylation of aminoimidazole ribonucleotide (AIR) to 5-amino-4-imidazole carboxylate ribonucleotide (CAIR) is provided by the observation that 21 out of a sample of 113 ad-2 mutants were affected by CO2. 19 of the mutants were stimulated by CO2 and 2 were inhibited. The majority of the CO2-stimulated mutants were confined to one section of the complementation map of the ad-2 locus. 相似文献
34.
A mutant of yeast sensitive to growth inhibition by 2,6-diaminopurine (2,6-DAP) was analyzed genetically and found to be a double mutant. One gene, dap, conferred approximately 30% sensitivity to the analogue. The other, slw, potentiated the inhibition such that the double mutant dap slw was inhibited 90%. The mutation dap conferred concomitant sensitivity to a number of other purine analogues. The activity of a purine phosphoribosyltransferase with 2,6-DAP in a strain carrying dap was found to be three times higher than in the wild type. It is inferred that the mutation alters the properties of a purine phosphoribosyltransferase. A possible mechanism for the effect of slw is also discussed. 相似文献
35.
36.
The Induction of Mitotic Recombination by Mitomycin C in Ustilago and Saccharomyces 总被引:12,自引:2,他引:10 下载免费PDF全文
Robin Holliday 《Genetics》1964,50(3):323-335
37.
The palm weevil, Rhynchophorus palmarum (L.), was collected in cocoons from red ring-diseased coconut palms (Cocos nucifera L.) in Trinidad and Tobago. Juveniles of five species of nematodes were extracted from the genitalia and macerated bodies of newly emerged adults of the palm weevil: Rhadinaphelenchus cocophilus (Cobb) Goodey (the red ring nematode), Teratorhabditis sp., Diplogasteritus sp., Mononchoides sp., and Bursaphelenchus sp. Over 90% of newly emerged weevil females and males were infested internally with red ring nematode juveniles, and over 47% of the weevils contained more than 1,000 red ring nematodes each. There was no significant correlation between weevil body length and the number of red ring nematodes carried internally by each weevil. Teratorhabditis sp. and Diplogasteritus sp. were extracted from over 50% of the palm weevils, and Monochoides sp. and Bursaphelenchus sp. were found in a small proportion of the weevils. Field-collected adult weevils were also internally and externally infested with a Rhabditis sp., which was not observed in or on weevils allowed to emerge from field-collected cocoons. 相似文献
38.
Lu Changya David V. Gallacher Robin F. Irvine Barry V. L. Potter Ole H. Petersen 《The Journal of membrane biology》1989,109(1):85-93
Summary We have examined the effects of various inositol polyphosphates, alone and in combination, on the Ca2+-activated K+ current in internally perfused, single mouse lacrimal acinar cells. We used the patch-clamp technique for whole-cell current recording with a set-up allowing exchange of the pipette solution during individual experiments so that control and test periods could be directly compared in individual cells. Inositol 1,4,5-trisphosphate (Ins 1,4,5 P3) (10–100 m) evoked a transient increase in the Ca2+-sensitive K+ current that was independent of the presence of Ca2+ in the external solution. The transient nature of the Ins 1,4,5 P3 effect was not due to rapid metabolic breakdown, as similar responses were obtained in the presence of 5mm 2,3-diphosphoglyceric acid, that blocks the hydrolysis of Ins 1,4,5 P3, as well as with the stable analoguedl-inositol 1,4,5-trisphosphorothioate (Ins 1,4,5 P(S)3) (100 m). Ins 1,3,4 P3 (50 m) had no effect, whereas 50 m Ins 2,4,5 P3 evoked responses similar to those obtained by 10 m Ins 1,4,5 P3. A sustained increase in Ca2+-dependent K+ current was only observed when inositol 1,3,4,5-tetrakisphosphate (Ins 1,3,4,5 P4) (10 m) was added to the Ins 1,4,5 P3 (10 m)-containing solution and this effect could be terminated by removal of external Ca2+. The effect of Ins 1,3,4,5 P4 was specifically dependent on the presence of Ins 1,4,5 P3 as it was not found when 10 m concentrations of Ins 1,3,4 P3 or Ins 2,4,5 P3 were used. Ins 2,4,5 P3 (but not Ins 1,3,4 P3) at the higher concentration of 50 m did, however, support the Ins 1,3,4,5 P4-evoked sustained current activation. Ins 1,3,4 P3 could not evoke sustained responses in combination with Ins 1,4,5 P3 excluding the possibility that the action of Ins 1,3,4,5 P4 could be mediated by its breakdown product Ins 1,3,4 P3. Ins 1,3,4,5 P4 also evoked a sustained response when added to an Ins 1,4,5 P(S)3-containing solution. Ins 1,3,4,5,6 P5 (50 m) did not evoke any effect when administered on top of Ins 1,4,5 P3. In the absence of external Ca2+, addition of Ins 1,3,4,5 P4 to an Ins 1,4,5 P3-containing internal solution evoked a second transient K+ current activation. Readmitting external Ca2+ in the continued presence internally of Ins 1,4,5 P3 and Ins 1,3,4,5 P4 made the response reappear. We conclude that both Ins 1,4,5 P3 and Ins 1,3,4,5 P4 play crucial and specific roles in controlling intracellular Ca2+ homeostasis. 相似文献
39.
Physical mapping of the von Recklinghausen neurofibromatosis region on chromosome 17 总被引:15,自引:9,他引:6 下载免费PDF全文
Jane W. Fountain Margaret R. Wallace Anne M. Brereton Peter O''''Connell Raymond L. White Donna C. Rich David H. Ledbetter Robin J. Leach R. E. Keith Fournier Anil G. Menon James F. Gusella David Barker Karen Stephens Francis S. Collins 《American journal of human genetics》1989,44(1):58-67
The von Recklinghausen neurofibromatosis (NF1) locus has been linked to chromosome 17, and recent linkage analyses place the gene on the proximal long arm. NF1 probably resides in 17q11.2, since two unrelated NF1 patients have been identified who possess constitutional reciprocal translocations involving 17q11.2 with chromosomes 1 and 22. We have used a somatic-cell hybrid from the t(17;22) individual, along with other hybrid cell lines, to order probes around the NF1 locus. An additional probe, 17L1, has been isolated from a NotI linking library made from flow-sorted chromosome 17 material and has been mapped to a region immediately proximal to the translocation breakpoint. While neither NF1 translocation breakpoint has yet been identified by pulse-field gel analysis, an overlap between two probes, EW206 and EW207, has been detected. Furthermore, we have identified the breakpoint in a non-NF1 translocation, SP-3, on the proximal side of the NF1 locus. This breakpoint has been helpful in creating a 1,000-kb pulsed-field map, which includes the closely linked NF1 probes HHH202 and TH17.19. The combined somatic-cell hybrid and pulsed-field gel analysis we report here favors the probe order D17Z1-HHH202-TH17.19-CRYB1-17L1-NF1- (EW206, EW207, EW203, L581, L946)-(ERBB2, ERBA1). The agreement in probe ordering between linkage analysis and physical mapping is excellent, and the availability of translocation breakpoints in NF1 should now greatly assist the cloning of this locus. 相似文献
40.
In West Africa, rice is grown in three constrasting ecosystems, upland, phreatic, and lowland, which is characterized by differing
water availability and soil properties. These ecosystems influence the predisposition of rice to disease problems, including
the grain discoloration complex. Discoloration of the hull was found to be most severe in the upland, less in the phreatic,
and least in the water-saturated lowland ecosystem. Caryopsis discoloration, however, showed no consistent pattern in relation
to the three ecosystems and was not correlated with hull discoloration, indicating that other factors are involved. 相似文献