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41.
Peter W. Goodenough Peter J. Kilshaw Fiona McEwan A. Jane Owen 《Bioscience reports》1986,6(8):759-766
The proteinases fromCarica papaya include papain, isoenzymes of chymopapain and two proteinases A and B distinguished by their unusually high pI. The identity of one of the most basic proteinases has been questioned. The present report describes the preparation and characterisation of two monoclonal antibodies that react specifically with papaya proteinases A and B respectively and a third that identifies a common structural feature found in papain and proteinase A. 相似文献
42.
Jane E. Mee 《Development genes and evolution》1986,195(8):506-512
Summary The effect of transverse fragmentation on the segment pattern of the short germ embryo of the locust Schistocerca gregaria has been investigated at two stages subsequent to the formation of the germ anlage. Following fragmentation both anterior and posterior partial embryos were observed, although rarely in a single egg. Anterior partial patterns usually terminated with a segment visible at the time of fragmentation or with the next segment due to appear. Posterior partial patterns began with a wide range of segments depending on the level of fragmentation.Anterior and posterior partial patterns developing in a single egg were usually not complementary and the segments missing sometimes included some segments visible when the embryo was fragmented. Non-complementary patterns resulted following fragmentation in all regions, while complementary patterns only occurred after fragmentation in the visibly-segmented region.The results suggest that following fragmentation isolated posterior portions of the embryo continue to form segments, while isolated anterior regions usually do not. This effect could result from variable damage to an existing pattern of unequally-sized segment primordia, or from the disruption of a process of sequential segmentation in the elongating posterior region of the embryo. The results are broadly compatible with the progress zone model proposed by Summerbell et al. (1973). 相似文献
43.
Jane C. Gallagher 《Journal of phycology》1983,19(4):539-542
Skeletonema costatum (Grev.) Cl. exhibits an asexual means, of increasing cell size that is more common than auxosporulation. This phenomenon accounts for the genetic stability of S. costatum in culture and for the deficiency of heterozygotes in natural populations, and has important implications far the life history of this species. 相似文献
44.
Net photosynthesis in the submersed angiosperms Myriophyllum spicatum L. and Hydrilla verticillata (L.f.) Royal was inhibited by 21% O2, but the degree of inhibition was greater for plants in the high than in the low photorespiratory state. Increasing the CO2 concentration from 50 through 2,500 l l-1 decreased the O2 inhibition of the high-photorespiration plants in a competitive manner, but it had no effect on the O2 inhibition of plants in the low photorespiratory state. Carbonic-anhydrase activity increased by almost threefold with the induction of the low photorespiratory state. Ethoxyzolamide, an inhibitor of carbonic anhydrase, reduced the net photosynthesis of low-photorespiration Myriophyllum and Hydrilla plants by 40%, but their dark respiration was unaffected. This ethoxyzolamide inhibition of net photosynthesis exhibited a competitive response to CO2 concentration, resulting in a decrease in the apparent affinity of photosynthesis for CO2. The net photosynthesis of plants in the high photorespiratory state was inhibited only slightly by ethoxyzolamide, and this inhibition was independent of the CO2 level. Ethoxyzolamide treatment caused an increase in the O2 inhibition of net photosynthesis of plants in the low photorespiratory state. Ethoxyzolamide increased the low CO2 compensation points of low-photorespiration Myriophyllum and Hydrilla, but the values for the high-photorespiration plants were unchanged. In comparison, the CO2 compensation points of the terrestrial plants Sorghum bicolor (C4), Moricandia arvensis (C3-C4 intermediate) and Nicotiana tabacum (C3) were unaltered by ethoxyzolamide treatment. These data indicate that the low photorespiratory state in Myriophyllum and Hydrilla is repressed by ethoxyzolamide treatment, thus implicating carbonic anhydrase as a component of the photorespiration-reducing mechanism in these plants. The competitive interaction of CO2 with ethoxyzolamide provides evidence that the low photorespiratory state in submersed angiosperms is the result of some type or types of CO2 concentrating mechanism. In Myriophyllum it may be via bicarbonate utilization, but in Hydrilla it probably takes the form of an inducible C4-type system.Abbreviations PEP
phosphoenolpyruvate
- RuBP
ribulose bisphosphate 相似文献
45.
F. T. de Dombal D. J. Leaper J. R. Staniland A. P. McCann Jane C. Horrocks 《BMJ (Clinical research ed.)》1972,2(5804):9-13
This paper reports a controlled prospective unselected real-time comparison of human and computer-aided diagnosis in a series of 304 patients suffering from abdominal pain of acute onset.The computing system''s overall diagnostic accuracy (91·8%) was significantly higher than that of the most senior member of the clinical team to see each case (79·6%). It is suggested as a result of these studies that the provision of such a system to aid the clinician is both feasible in a real-time clinical setting, and likely to be of practical value, albeit in a small percentage of cases. 相似文献
46.
It was found that ethionine partially inhibits the transport of the inducer (TMG) of β-galactosidase into the cells ofEscherichia coli ML-30. The synthesis of β-galactosidase-specific messenger RNA is not inhibited. Ethionine appears to be incorporated into
proteins synthesized by the strains used. The incorporation of ethionine into the molecule of β-galactosidase results in the
synthesis of an enzymically inactive, immunologically cross-reacting protein. 相似文献
47.
48.
49.
SPERMIOGENESIS IN WILD TYPE AND IN A MALE STERILITY MUTANT OF DROSOPHILA MELANOGASTER 总被引:3,自引:1,他引:2 下载免费PDF全文
Jane Rearick Shoup 《The Journal of cell biology》1967,32(3):663-675
Spermiogenesis in the translocation heterozygote T (1; 2H) 25(20) y l 25/FM6 has been studied with the electron microscope and compared with that in wild type males. It appears that the genetic lesion in the male sterility mutant is associated primarily with a failure in differentiation of the head. In wild type flies, the spermatid nucleus assumes a conchoidal shape; chromatin accumulates along the convex surface. Adjacent to the concave surface a large bundle of microtubules runs parallel to the long axis of the spermatid. A single row of microtubules is juxtaposed against the convex surface of the head. As differentiation proceeds, the nucleus elongates, chromatin condenses, and the nucleus is compacted to a final diameter of about 0.3 µ. In the sterile mutant the spermatid nucleus has an irregular or wedge-shaped profile and no concavity is formed, nor is the bundle of microtubules observed. The row of microtubules, however, is usually present around the periphery. The change from lysine-rich to arginine-rich histone in mature wild type sperm does not occur in the sterile male. The substructure of the axial filament and mitochondrial derivatives, however, are similar to those in wild type. 相似文献
50.
Ethionine at concentrations of 10−3M, 5×10−3M and 10−2M inhibits growth, both of β-galactosidase inducible ML-30 and constitutive ML-308Escherichia coli strains. The protein synthesis (measured by the incorporation of l-leucine-14C and l-aspartic-14C acid into proteins) of these strains is inhibited to the same extent as their growth. The synthesis of inducible and constitutive
β-galactosidase produced by the strains ML-30 and ML-308, respectively, is considerably inhibited by ethionine. 相似文献