Effect of estrogen on Xenopus laevis albumin mRNA levels

Accurate quantitation of concentrations of albumin mRNA by hybridization to albumin cDNA allows analysis of the estrogen effect on the Xenopus laevis albumin mRNA levels in the liver cytoplasm during the primary stimulation. Administration of estradiol-17 beta to male Xenopus laevis increases the amount of both total cellular RNA and poly(A)-RNA but has no effect on the albumin mRNA level and the amount of albumin mRNA per cell is constant.     

Hybridization of biotinylated oligo(dT) for Eukaryotic mRNA quantitation

Quantitation of mRNA content in samples of total cellular RNA is required for the analysis of Northern blot hybridization to estimate the relative level of specific gene expression. Commonly used methods based on UV absorbance and dye staining measure only total RNA, and mRNA normalization by probing for mRNA levels of housekeeping genes, such as β-actin and glyceraldehyde-3-phosphate dehydrogenase, assumes a constant level of their expression, which, in fact, may vary as a function of cell proliferation and differentiation. We describe here a nonradioactive, slot-blotting method for quantifying eukaryotic mRNA levels using a biotinylated oligo(dT) probe, which hybridizes directly to the 3′-polyadenylated sequence of eukaryotic mRNAs. The method provides a more accurate estimation of mRNA content in total RNA samples and should be applicable for quantitative Northern analysis.     

Two closely linked transcription units within the 63B heat shock puff locus of D. melanogaster display strikingly different regulation

We report the isolation and characterization of a cloned DNA of D. melanogaster, Dm4L, that is derived from the major heat shock puff site at 63B. This segment contains two closely linked genes that are each present once per Drosophila haploid genome. One of these, the hsp 83 gene, encodes an abundant heat shock mRNA that, unlike other major heat shock mRNAs, is also abundant in uninduced (23 degrees) kco cells. Although only a slight increase in the level of total hsp 83 RNA can be detected after heat shock in Kco cells, the level of hsp 83 poly(A)+ mRNA increases more than 6-fold and the level of pulse-labeled hsp 83 RNA in total cellular RNA increases 11-fold relative to uninduced cells. In contrast, the levels of total, poly(A)+, and pulse-labeled RNA homologous to the second gene, 63B-T2, are approximately the same in both induced and uninduced cells. Hence, even though these genes are separated by only one thousand base pairs, and, from in situ hybridization to polytene chromosomes, both lie within the heat shock puff, they display strikingly different regulatory properties, These results demonstrate that close linkage of a gene to a heat shock puff is not sufficient to render its expression heat inducible.     

Cellular localization of induced human interferon-beta mRNA by non-radioactive in situ hybridization

Induced interferon-beta (IFN-beta) mRNA was localized in human FS-4 fibroblasts by in situ hybridization using biotinylated probes. The hybridization sites were detected by incubation with a nick-translated genomic DNA probe (1.8 kb) via streptavidin-colloidal gold followed by silver contrast enhancement. The positive signals were observed by reflection-contrast light microscopy. IFN-beta mRNA was transiently induced by poly r(I): r(C) in fibroblasts 2-4 h after induction. Induction in the presence of cycloheximide and actinomycin D (superinduction conditions) exhibited an enhanced level of IFN-beta mRNA with a maximum at 4-8 h. The kinetics of the IFN-beta mRNA expression in the cytoplasm as revealed by in situ hybridization proved to be compatible with the results of Northern blotting experiments of total cellular RNA.     

Changes in relaxin precursor mRNA levels in the rat ovary during pregnancy

Levels of preprorelaxin mRNA in the rat ovary during pregnancy were determined by cell-free translation and by hybridization analyses with cloned preprorelaxin cDNA. Translation of poly(A+) RNA from rat ovaries taken at different stages of pregnancy resulted in the incorporation of [35S]cysteine into two peptides, of Mr 17,500 and 20,500, that were specifically bound by anti-relaxin IgG. Both peptides also were demonstrated by translation of ovarian poly(A+) RNA that was hybrid-selected with cloned preprorelaxin cDNA, the sequence of which corresponds to the Mr 20,500 peptide. The origin of the Mr 17,500 putative precursor is not presently known. Preprorelaxin mRNA translational activities corresponded to previously reported concentrations of relaxin in rat ovaries during pregnancy. The results of hybridization analyses, both by Northern blotting of poly(A+) RNA and dot blotting of unfractionated RNA, agreed with those of translation assays. Preprorelaxin mRNA activity/concentration was low in early pregnancy, rose markedly and reached a plateau on days 15-20 (about 1-2% of total translation activity), and then fell to low levels again by day 23, the time of parturition. These findings indicate that the concentration of relaxin in the rat ovary is directly dependent on preprorelaxin mRNA levels.     

Androgens positively regulate follicle-stimulating hormone beta-subunit mRNA levels in rat pituitary cells

We have shown previously that androgens negatively regulate LH alpha and beta-subunit mRNA levels, but have little or no effect on FSH beta mRNA levels in rats in vivo. In contrast, estrogen negatively regulates all three gonadotropin subunit mRNA levels in vivo. We have examined the effects of these sex steroids on gonadotropin subunit synthesis directly at the level of the pituitary gland by using cultured rat pituitary cells. Adult female and male rat pituitaries were dissected, dispersed enzymatically, and maintained in culture for 2 days. At that time, cells were treated for varying lengths of time with either medium alone or sex-steroid hormone treatments (estradiol or testosterone). Dose-response and time-course experiments were performed. Cells were then harvested and total RNA was extracted. Gonadotropin subunit mRNA levels were assessed by blot hybridization techniques. Sex-steroid hormones were added to achieve final concentrations ranging from 10(-12) to 10(-6) M for dose response experiments and 10(-8) M for time-course experiments. Testosterone treatment (10(-8) M) increased FSH beta mRNA levels 3-fold in females (P less than 0.01) and males (P less than 0.05), but had no effect on alpha or LH beta mRNA levels in either sex. Dose-related increases in FSH beta mRNA levels with increasing concentrations of testosterone were observed in both female and male pituitary cell cultures. Time-course studies revealed that the testosterone-stimulated increases in FSH beta mRNA levels are statistically significant by 12 h and 6 h after hormone addition in female and male cultures, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Elastin mRNA levels during foetal development of sheep nuchal ligament and lung. Hybridization to complementary and cloned DNA

Elastin mRNA levels were quantified in sheep nuchal ligament and lung during the latter half of foetal development with elastin-specific cDNA (complementary DNA) probes using both hybridization in solution (saturation analysis) and hybridization on a fixed support (Northern analysis). For the solution-hybridization studies, cDNA prepared from nuchal-ligament mRNA was enriched to 65% for elastin sequences by hybridizing it to its template at a R0t (mol X s X litre-1) value that included only the abundant class of mRNA sequences. Hybridization of this probe to RNA extracted from nuchal ligament between 70 and 138 days after conception demonstrated elastin sequences increased about 10-fold (from 0.047 to 0.438% of total RNA). In contrast, lung elastin mRNA levels increased only 3-fold (from 0.009 to 0.022% of total RNA) during the same period. Over this development period these values correspond to increases in the average number of elastin mRNA molecules from 950 to 20 000 molecules/ligament cell and from 130 to 330 molecules/lung cell. For Northern analysis, elastin mRNA was purified from near-term-sheep nuchal ligament on sucrose density gradients. Analysis of the translation products of this elastin mRNA showed that relative elastin precursor synthesis was at least 80% of total [3H]valine incorporation. The Mr of this elastin mRNA, determined by methylmercury-agarose-gel electrophoresis, was approx. 1.25 X 10(6). Northern hybridization of nuchal ligament and lung RNA to a [32P]cDNA probe, transcribed from this sucrose-gradient-purified elastin mRNA, confirmed the developmental changes in elastin mRNA levels detected by solution-hybridization techniques. The specificity of this method was confirmed by using a cloned elastin gene fragment. These studies demonstrate that elastin mRNA levels in organs such as nuchal ligament and lung increase with foetal development, but that there are significant differences in the average cellular elastin mRNA content of these two organs.     

Utilizing RNA/DNA hybridization to directly quantify mRNA levels in microbial fermentation samples

mRNA quantification has become a research hotspot. Quantitative real-time RT-PCR is a popular method but is known to lack precision. To rapidly monitor the kinetics of mRNA levels for the control of microbial fermentation processes, we developed an SYBR Green I-based universal method to directly quantify mRNA from fermentation samples. After total RNA was extracted, the mRNA was hybridized and protected by a longer DNA oligonucleotide. The probe length determined the strength of signal amplification. S1 nuclease and RNase A were used to remove excess probe, single-stranded RNA, and mis-matched RNA/DNA hybrids. Finally, the perfect-matched RNA/DNA hybrid was quantified by SYBR Green I dye. The conditions of liquid hybridization and enzyme digestion were systemically optimized. The kinetic tendency of phzC mRNA levels during phenazine-1-carboxylic acid fermentation was consistent with the results from MB hybridization in our previous report. The detection of mRNA levels of ten genes in Pseudomonas sp. M18G proved that this method is universal and feasible for mRNA quantification, and has great potential for application in mRNA quantification in various organisms.     

人肝细胞癌及其配对非癌肝组织、正常肝组织中热休克蛋白Hsp90基因mRNA水平的分析

 为定量分析和比较 2 2对人肝细胞癌 (HCC)及其配对非癌肝组织 (PNL)和 2例正常肝 (NL)组织中热休克蛋白Hsp(heatshockprotein) 90基因mRNA的表达水平 ,用狭缝杂交法检测hsp90 βmRNA的表达 ;并进一步用以特异性复合cRNA为内参照的定量RT PCR法对hsp90α和hspβmRNA的表达进行分析比较 .狭缝杂交结果显示 ,hsp90 βmRNA在 1 3例 ( 59 1 % )PNL中的表达平均升高至NL的 1 87倍 ;在 2 1例 ( 95 5% )HCC中的表达平均升高至NL的 3 45倍 ;在 2 0例 ( 90 9% )HCC中的表达平均升高至PNL的 2 75倍 .以cRNA为内参照的mRNA定量RT PCR结果显示 ,hsp90αmRNA在1 8例 ( 81 8% )PNL中的表达平均升高至NL的 3 0 6倍 ;在全部 2 2例HCC中的表达平均升高至至PNL的 2 0 8倍和NL的 5 1 0倍 .hsp90 βmRNA仅在小部分 ( 8例 ,36 4% )PNL中的表达轻度升高至NL的 1 2 7倍 ,而在全部 2 2例HCC中的表达显著升高至PNL的 2 95倍和NL的 2 52倍 .hsp90α和hsp90 β可能分别在人HCC发生、发展的不同阶段发挥不同的作用 ;以cRNA为内参照的定量RT PCR法是较狭缝杂交法更为灵敏、准确和快捷的mRNA定量分析方法 .     

Expression in yeast of antisense RNA to ADE1 mRNA

The utility of antisense RNA as a means of regulating gene expression in yeast has been explored by inserting into a high copy number yeast expression vector an ADE1 gene fragment in such an orientation so as to produce antisense RNA in vivo which could hybridize to natural ADE1 mRNA. Northern blotting analysis of total cellular RNA extracted from transformed yeast cells confirmed the presence of high levels of antisense RNA to ADE1 mRNA within cells. However the high level of expression of antisense RNA did not result in production of Ade- cells.     

Detection of rare mRNA species in a complex RNA population by blot hybridization techniques: a comparative survey

The detection of very rare mRNA species in a complex RNA preparation by current RNA blotting techniques is not straightforward. To be able to determine the size of mRNA molecules representing 10(-6) to 10(-7) of the total mass of an RNA preparation, a quantitative comparison of the level of detection of denatured mRNA species electrophoretically separated on agarose gels, followed by transfer to either nitrocellulose or diazobenzyloxymethyl (DBM) paper and hybridization to specific cDNA probes was carried out. Different transfer procedures were analyzed. Optimal conditions have been found which allowed the detection of RNA bands containing as little as 5 pg of a specific sequence within a few days of autoradiography following hybridization with highly labeled [32P]cDNA probes. Using this procedure it was shown that the low amounts of alpha-fetoprotein (AFP) mRNA sequences present in adult rat liver are mature AFP mRNA molecules.