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51.
The mRNAs coding for the 68,000 and 74,000 dalton serum albumins of Xenopus laevis were purified by hybridisation to their corresponding cloned cDNA and translated using the reticulocyte lysate. The primary translational product of the 68,000 dalton albumin has a molecular weight of 70,000 daltons suggesting that it is synthesised with a signal peptide which is cleaved during secretion. In contrast, the primary translational product of the 74,000 dalton albumin has a molecular weight of 72,000 daltons suggesting that it must be posttranslationally modified to account for the increased molecular weight of the mature protein. X. laevis oocytes injected with albumin mRNA secrete proteins of the same molecular weights as the mature albumins. When these translational products were chromatographed on concanavalin A Sepharose, the 74,000 dalton albumin was bound suggesting that it is glycosylated. Comparison of X. laevis and X. tropicalis albumins suggests that the 68,000 dalton albumin is similar to the primitive Xenopus albumin and that since the genome duplication which occurred in X. laevis , differences have arisen in both the length and processing of the primary translational product to account for the current difference in the molecular weights of the two X. laevis albumins. 相似文献
52.
SANDRA J. SMITH-GILL J. GARRETT REILLY ELISABETH M. WEBER 《Development, growth & differentiation》1979,21(4):281-290
The relationship of DNA synthesis and cellular turnover to biochemical differentiation during metamorphosis of R. pipiens liver was investigated. Average DNA/cell was constant at 11.6 pg/ nucleus through stage XXV; but increased during juvenile growth; during metamorphosis stages, changes in total DNA content must correspond to changes in cell number. Rates of DNA synthesis were estimated by rates of 3H-thymidine incorporated into the acid-precipitable fractions, corrected for both precursor uptake into the acid-soluble pool, and for endogenous thymine pool size. DNA content increased steadily from premetamorphosis until late prometamorphosis; at preclimax stages XVIII and XX there were two successive decreases in DNA content of approximately 30%. Fluctuations in synthesis rates preceded corresponding fluctuations in content; DNA synthesis was maximal at stages XVI and XVIII, decreased nearly ten-fold at metamorphic climax, and then gradually rose again during late climax stages. The size of the endogenous thymine pool increased transitorily during spontaneous metamorphosis corresponding to a stage of maximal DNA synthesis. These results indicate that both DNA synthesis and cellular turnover play a significant role in determining net DNA synthesis rates and content during metamorphosis. Metamorphosis of the tadpole liver appears to be associated with both proliferation and cellular death, perhaps a replacement of “larval” by “adult” cells. Metamorphosis of the liver cannot be occuring in a “fixed population of cells” as is commonly assumed. An interpretation of the population dynamics of the metamorphic liver is presented. 相似文献
53.
Marcela Víquez-Zamora Myluska Caro Richard Finkers Yury Tikunov Arnaud Bovy Richard GF Visser Yuling Bai Sjaak van Heusden 《BMC genomics》2014,15(1)
Background
A RIL population between Solanum lycopersicum cv. Moneymaker and S. pimpinellifolium G1.1554 was genotyped with a custom made SNP array. Additionally, a subset of the lines was genotyped by sequencing (GBS).Results
A total of 1974 polymorphic SNPs were selected to develop a linkage map of 715 unique genetic loci. We generated plots for visualizing the recombination patterns of the population relating physical and genetic positions along the genome.This linkage map was used to identify two QTLs for TYLCV resistance which contained favourable alleles derived from S. pimpinellifolium. Further GBS was used to saturate regions of interest, and the mapping resolution of the two QTLs was improved. The analysis showed highest significance on Chromosome 11 close to the region of 51.3 Mb (qTy-p11) and another on Chromosome 3 near 46.5 Mb (qTy-p3). Furthermore, we explored the population using untargeted metabolic profiling, and the most significant differences between susceptible and resistant plants were mainly associated with sucrose and flavonoid glycosides.Conclusions
The SNP information obtained from an array allowed a first QTL screening of our RIL population. With additional SNP data of a RILs subset, obtained through GBS, we were able to perform an in silico mapping improvement to further confirm regions associated with our trait of interest. With the combination of different ~ omics platforms we provide valuable insight into the genetics of S. pimpinellifolium-derived TYLCV resistance.Electronic supplementary material
The online version of this article (doi:10.1186/1471-2164-15-1152) contains supplementary material, which is available to authorized users. 相似文献54.
Background
SRY is the pivotal gene initiating male sex determination in most mammals, but how its expression is regulated is still not understood. In this study we derived novel SRY 5' flanking genomic sequence data from bovine and caprine genomic BAC clones. 相似文献55.
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In a review of 106 cases of carcinoma of the thyroid gland, it was noted that a solitary thyroid nodule is the most outstanding single physical sign in this disease. It should be investigated by biopsy of a specimen removed at operation. Patients and physicians were sometimes guilty of delay in this regard. Papillary carcinoma involved multiple foci within the gland in at least half of the cases and there was a high incidence of regional lymph node metastasis associated with this type. Doubt was cast on conclusions by other investigators that carcinoma of the thyroid rarely is lethal in patients less than 40 years of age. 相似文献
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60.
Ethylene and ethane production in response to salinity stress 总被引:1,自引:1,他引:0
Abstract Ethylene and ethane production in mung bean hypocotyl sections were evaluated as possible indicators of stress due to contact with four salts that are common in natural sites. Ethylene production decreased with increasing concentrations of applied NaCl and KCl. When CaCl2 was applied, the ethylene evolution was greater. However, when MgCl2 was applied, ethylene evolution remained high then decreased and at higher salt concentrations again showed an increase. NaCl (up to 0.1 kmol m?1) and KCl (up to 0.5 kmol m?3) caused a concentration-dependent increase in ethane production. The ethane production with CaCl2 was the lowest among the salts tested and only a minute increase was noticed with the increase of concentration from 0.01 to 1 kmol m?3. Ethane production showed a distinct maximum at 0.2 kmol m?3 MgCl2. The introduction of 0.01 kmol m?3 CaCl2, as well as anaerobic conditions obtained by purging vials with N2, eliminated that high ethane production. Respiratory activity of the mung bean hypocotyl sections in MgCl2 concentrations from 0 to 0.5 kmol m?3 was correlated with ethane but not with ethylene production. The ethane/ethylene ratio showed three patterns for the four salts tested. 相似文献