Newly expressed progesterone receptor cannot activate stable, replicated mouse mammary tumor virus templates but acquires transactivation potential upon continuous expression

During development and differentiation, the expression of transcription factors is regulated in a temporal fashion. Newly expressed transcription factors must interact productively with target genes organized in chromatin. Although the mechanisms governing factor binding to chromatin templates are not well understood, it is now clear that template access can be dramatically influenced by nucleoprotein structure. We have examined the ability of a well characterized transactivator, the progesterone receptor (PR), to activate the mouse mammary tumor virus (MMTV) promoter organized either in stable, replicating templates that have a highly ordered nucleosome structure or as transiently transfected DNA, which adopts a less-defined structure. If the PR is transiently expressed in cells harboring both replicated and transient MMTV receptor constructs, it cannot significantly activate the stable replicated MMTV template. In contrast, when PR cDNA is stably inserted into the same cells and constitutively expressed, it gains the ability to activate both chromosomal and transiently introduced templates. These results demonstrate that newly expressed PR is not competent to activate the MMTV template in its native nucleoprotein conformation but acquires this ability upon prolonged expression in replicating cells.

DNA sequence analysis of human chromosome 21 notI linking clones

Portions of 16 chromosome 21 NotI linking clones were sequenced. These linking clone sequences represent sequence-tagged restriction sites that are potentially useful for finding genes and for finer genome mapping and sequencing. All of the clones were G+C rich (54 to 83%). CpG and GpC dinucleotide frequencies were very close to the expected values based on base composition and were very similar in 15 of the clones. Most of the NotI linking clones were derived from CpG islands, which are often associated with genes. Five NotI linking clones had a high potential for coding regions; 7 additional clones may also contain coding regions. The NotI linking clones had many short homologous regions, but no extensive homologies either with each other or with GenBank sequences.

Faculty have few incentives for becoming board certified in pharmacotherapy

A telephone survey of all colleges of pharmacy in the United States (including Puerto Rico) and Canada was conducted to assess the incentives offered for pharmacy practice faculty to become board-certified pharmacotherapy specialists (BCPS). Board certification is not a requirement for employment at any college of pharmacy; however, it plays a part in promotion, tenure, and merit salary increases at several schools. Fewer than half of the schools provide at least partial reimbursement of examination-related expenses. Sixteen have initiated BCPS study groups. We perceive that faculty must have more incentives to take the examination. It may be difficult to change institutional policies regarding merit increases or promotion and tenure, but colleges of pharmacy can do more to decrease the cost burden and to promote study groups within the department.

Modulation of the ligand-independent activation of the human estrogen receptor by hormone and antihormone

It has been previously demonstrated that several members of the steroid receptor superfamily may be activated by the neurotransmitter dopamine in the apparent absence of cognate ligand. We have examined wild-type and mutant human estrogen receptors (ERs, [Gly400]ER and [Val400]ER, respectively) for their abilities to activate ER-dependent transcription of a transgene in a ligand-independent manner. In cells expressing the wild-type ER, dopamine was nearly as effective as 17 beta-estradiol at inducing the chloramphenicol acetyltransferase activity of the reporter gene in a dose-dependent manner; simultaneous addition of suboptimal concentrations of 17 beta-estradiol and dopamine stimulated transcription more than either compound alone. Dopamine alone was unable to induce gene expression in cells expressing [Val400]ER mutant receptors, but concomitant treatment with 17 beta-estradiol produced a synergistic increase in transcription, suggesting that the ligand may alter the mutant receptor's conformation such that it can be activated subsequently by a dopaminergic signaling mechanism. In the presence of the antiestrogen ICI 164,384, dopamine-stimulated gene expression was undetectable in cells expressing either form of ER. However, simultaneous treatment of cells expressing wild-type ER with trans-4-hydroxytamoxifen and dopamine resulted in transgene expression that was additive in nature compared to either compound alone; similar treatment of cells expressing [Val400]ER produced a synergistic increase. Our results suggest that ligand and ligand-independent activation of the ER initiate from distinct pathways and that the latter may occur in a variety of target tissues subject to modulation by receptor ligands.

Atomic force microscopy of biochemically tagged DNA

Small fragments of DNA of known length were made with the polymerase chain reaction. These fragments had biotin molecules covalently attached at their ends. They were subsequently labeled with a chimeric protein fusion between streptavidin and two immunoglobulin G-binding domains of staphylococcal protein A. This tetrameric species was expected to bind up to four DNA molecules via their attached biotin moieties. The DNA-protein complex was deposited on mica and imaged with an atomic force microscope. The images revealed the protein chimera at the expected location at the ends of the strands of DNA as well as the expected dimers, trimers, and tetramers of DNA bound to a single protein.

The 0.7 to 3.3 megabase chromosomes from Candida, Kluyveromyces, and Pichia provide accurate size standards for pulsed field gel electrophoresis

Pulsed field gel electrophoresis was used to size intact chromosomal DNAs from Candida albicans, Kluyveromyces lactis, Pichia scolyti, and Pichia mississippiensis by optimization methods using, as size standards, concatenated bacteriophage lambda DNA, and intact and NotI digestion products of Schizosaccharomyces pombe chromosomal DNAs. These newly sized fungal DNAs can now serve as convenient and accurate size standards for DNA molecules between 0.7 and 3.3 megabases (Mb). These size standards are valid over a wide range of different electrophoretic conditions.

Oncogene ect2 is related to regulators of small GTP-binding proteins

We have developed an efficient expression cloning system that allows rapid isolation of complementary DNAs able to induce the transformed phenotype. We searched for molecules expressed in epithelial cells and possessing transforming potential to fibroblasts, and cloned a cDNA for the normal receptor of a growth factor secreted by NIH/3T3 cells. Here we report a second novel transforming gene, ect2. The isolated cDNA is activated by amino-terminal truncation of the normal product. The Ect2 protein has sequence similarity within a central core of 255 amino acids with the products of the breakpoint cluster gene, bcr (ref. 5), the yeast cell cycle gene, CDC24 (ref. 6), and the dbl oncogene. Each of these genes encodes regulatory molecules or effectors for Rho-like small GTP-binding proteins. The baculovirus-expressed Ect2 protein could bind highly specifically to Rho and Rac proteins, whereas the dbl product showed broader binding specificity to Rho family proteins. Thus ect2 is a new member of an expanding family, whose products have transforming properties and interact with Rho-like proteins of the Ras superfamily.

PCR amplification of megabase DNA with tagged random primers (T-PCR)

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Extracting dynamic parameters from speech movement data

A quantitative characterization of articulatory movements, using the parameter values of a linear second-order dynamical system, was developed in order to compare classes of movements, in particular, classes defined by linguistic factors such as syllable position, stress, and vowel quality. Movements of the lower lip in utterances such as ['bibebib] and [babe'bab] were partitioned into sections ("windows") in two ways: at successive displacement peaks and valleys, and at the right edge of plateau regions around such extreme values. The linguistic factors affected natural frequency in similar ways regardless of whether damping ratio was permitted to vary or held fixed at one of several different values. Damping ratio was generally unaffected by the linguistic factors. For the most part, the type of partition or window did not affect the patterns of the results, with the exception of the closing gesture out of the reduced syllable.

Spatial and temporal distribution of corticosteroid-binding globulin and its messenger ribonucleic acid in embryonic and fetal mice

Glucocorticoids influence fetal development, and their actions are regulated by plasma corticosteroid-binding globulin (CBG). Immunohistochemistry and in situ hybridization were, therefore, used to localize CBG and its mRNA in sections of embryonic and fetal mice and their associated placental tissues from day 5 of gestation until term (day 19). In the fetus, CBG mRNA was first detectable in the hepatocytes on day 11 of gestation. The amount of CBG mRNA in these cells increased transiently to a maximum on days 15-16 of gestation and was negligible by day 19. In hepatocytes, CBG immunoreactivity correlated with the distribution and relative abundance of CBG mRNA. The fetal exocrine pancreas also contained CBG mRNA, but this was only present on days 15-16 of gestation, while immunoreactive CBG persisted in these cells until term. Immunoreactive CBG was detected in the tubular cells of the developing fetal kidney as early as day 13, but CBG mRNA was never found in the fetal kidney, suggesting that the protein is probably sequestered from fetal blood directly or via the glomerular filtrate. The placenta contained immunoreactive CBG throughout gestation, even before its detection in fetal tissues, and it was most abundant in the spongiotrophoblasts and the extracellular matrix surrounding fetal and maternal capillaries. However, CBG mRNA was not detected in the placenta at any gestational age. Therefore, CBG present in the placenta is most likely of maternal origin and may influence the activities of steroid hormones that control placental development and/or function. The presence of smaller immunoreactive polypeptides in placental extracts, compared to CBG in corresponding maternal serum samples, suggests that this process may involve an interaction between maternal CBG and placental proteinases. The results presented here suggest that temporal and spatial changes in the localization of CBG and its mRNA in the fetus may influence the effects of steroid hormones on developing tissues.

Reduced sensitivity to intra-oesophageal acid in patients with reflux-induced strictures

Patients presenting with benign reflux-induced oesophageal strictures often have no antecedent symptoms of reflux, which might be a consequence of decreased oesophageal sensitivity. This has been investigated in 36 patients with strictures and 30 patients with uncomplicated oesophagitis by means of a visual analogue scale (0 to 10) to assess preceding symptoms and acid perfusion tests to assess oesophageal sensitivity. Patients with strictures had lower symptom scores (median, 2.7) than those with uncomplicated oesophagitis (median, 4.85) and were more likely to have a negative acid perfusion test (18 of 28 compared with 6 of 23, respectively; p < 0.05). Furthermore, the volumes of acid perfused at the onset of symptoms in the stricture group (median, 80 ml) were greater than in the oesophagitis group (median, 40; p < 0.05). These results support the hypothesis that patients who develop reflux-induced strictures have decreased sensitivity to intra-oesophageal acid. This may be a factor in the pathogenesis of reflux-induced strictures.

A streptavidin mutant containing a cysteine stretch that facilitates production of a variety of specific streptavidin conjugates

The ability to produce specific streptavidin conjugates has been considerably enhanced by using a streptavidin mutant containing a cysteine stretch, in which sulfhydryl groups serve as unique conjugation sites. A streptavidin molecule containing five cysteine residues at its C-terminus, referred to as Stv-28, was efficiently expressed in Escherichia coli, and purified to homogeneity. Purified Stv-28 had full biotin-binding ability and formed a subunit tetramer. Reactive sulfhydryl groups of Stv-28, derived solely from the cysteine stretch, greatly facilitate the specific conjugation of partner molecules to streptavidin by simple sulfhydryl chemistry. In this manner, S-[14C]carboxymethylated streptavidin and a streptavidin-fluorescein conjugate were prepared. These conjugates contain almost twenty [14C]carboxymethyl groups and fluorescein molecules, respectively, per subunit tetramer, indicating that the sulfhydryl groups of the cysteine stretch are fully reactive. More importantly, these conjugates retain full biotin-binding ability and form subunit tetramers, suggesting that the fundamental properties of streptavidin would be unaffected by the conjugation of other partner molecules to the C-terminal cysteine stretch.

Cloning and characterization of EagI YACs from human chromosome 21

Yeast artificial chromosomes (YACs) were made from a total EagI digest of DNA from a mouse-human chromosome 21 hybrid cell line. Approximately 3750 YACs, corresponding to 75-125 human YACs, with an average size of approximately 100 kb were recovered. Southern hybridization indicates that the chimera frequency in this library may be less than 3%. Thirty-four of the human EagI YACs were regionally assigned by a number of methods. Some YACs were regionally assigned to one of six chromosome regions by hybridization of Alu-PCR products from the YAC against Alu-PCR-amplified DNA from a panel of hybrid cell lines that contain various parts of chromosome 21. Additional YACs were regionally assigned by fluorescence in situ hybridization using either biotinylated Alu-PCR products or yeast genomic DNA from the YAC-containing strains as probes. The regionally assigned EagI YACs are located preferentially in two regions of the chromosome: near the q telomere and in the p-arm ribosomal gene region.

Myelodysplasia, vasculitis and anti-neutrophil cytoplasm antibodies

A cutaneous or systemic vasculitis occurs in myelodysplasia as well as in myeloproliferative and lymphoproliferative disorders. The most common lesion is a leucocytoclastic vasculitis, with neurological or joint involvement occurring less often. The vasculitis may appear contemporaneously with or precede the clinical onset of the blood dyscrasia. Occasionally the lesions respond dramatically to the use of steroids but in general, patients with vasculitis have a worse prognosis than those with uncomplicated myelodysplasia. Vasculitis and myelodysplasia appear together too often for the association to be coincidental and the vasculitis in most cases cannot be attributed to intercurrent infections, therapeutic agents or a pre-existing rheumatological disorder. While autoantibodies are frequently present in myelodysplasia, and ANA and anti-neutrophil cytoplasm antibodies (ANCA) are found in other vasculitides, neither of these antibodies is associated with the vasculitis of myelodysplasia. There has however been one report of ANCA in Sweet's syndrome a non-vasculitic skin condition that also occurs in the myelodysplastic syndromes.

Detection and characterization of a ring chromosome in the fission yeast Schizosaccharomyces pombe

NotI and SfiI genomic restriction maps were used to detect and characterize a ring chromosome II in a Schizosaccharomyces pombe strain with a meiotic defect on chromosome II. The ring chromosome was formed by an intrachromosomal fusion near, or at, the very ends of chromosome II.

Cloning of an ovine 11 beta-hydroxysteroid dehydrogenase complementary deoxyribonucleic acid: tissue and temporal distribution of its messenger ribonucleic acid during fetal and neonatal development

Glucocorticoids promote the development of many organ systems vital for extrauterine survival, and fetal cortisol provides the trigger for birth in sheep. The activity of glucocorticoids may be influenced at a cellular level by 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD), which is responsible for the interconversion of cortisol and cortisone. To examine 11 beta-HSD gene expression during fetal development, two overlapping clones which yield a 1.4 kilobase (kb) complementary DNA encoding sheep 11 beta-HSD from a liver library were isolated by using a rat 11 beta-HSD cDNA as the probe. This cDNA contains a 879 base pair open reading frame for a protein of 292 amino acids that has more than 70% sequence identity to rat and human 11 beta-HSDs. To define the tissue distribution of 11 beta-HSD messenger RNA in sheep, selected tissues were collected from one fetus at day 130 and term (approximately 145 days), and from a nonpregnant ewe. Cellular RNA was extracted and subjected to Northern blot analysis, and a single 1.8 kb transcript was detected in the fetal and adult liver, lung, hypothalamus, anterior pituitary, and placenta. This was undetectable in adrenals and kidneys, but a smaller (1.5 kb) transcript was present in fetal and adult kidney RNA. The relative abundance of 11 beta-HSD mRNA was greatest in fetal and adult livers, and it was much higher in adult liver, lung, and kidney than in the corresponding fetal tissues. To examine whether 11 beta-HSD gene expression is developmentally regulated in the fetal sheep, liver, lung, and kidney tissues were taken from fetuses at day 60-70, day 100-110, day 125-130, at term, and from newborn lambs (24-48 h old). In the lung and kidney, the relative abundance of 11 beta-HSD mRNA did not change from day 60 to term but increased in the lungs of newborn lambs. In contrast, 11 beta-HSD mRNA levels in the liver increased between day 125 and term and rose further in the newborn. Collectively, these results demonstrate that 11 beta-HSD gene expression in sheep is regulated in a tissue-specific and developmentally programmed manner.

VDE endonuclease cleaves Saccharomyces cerevisiae genomic DNA at a single site: physical mapping of the VMA1 gene

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Immuno-PCR: very sensitive antigen detection by means of specific antibody-DNA conjugates

An antigen detection system, termed immuno-polymerase chain reaction (immuno-PCR), was developed in which a specific DNA molecule is used as the marker. A streptavidin-protein A chimera that possesses tight and specific binding affinity both for biotin and immunoglobulin G was used to attach a biotinylated DNA specifically to antigen-monoclonal antibody complexes that had been immobilized on microtiter plate wells. Then, a segment of the attached DNA was amplified by PCR. Analysis of the PCR products by agarose gel electrophoresis after staining with ethidium bromide allowed as few as 580 antigen molecules (9.6 x 10(-22) moles) to be readily and reproducibly detected. Direct comparison with enzyme-linked immunosorbent assay with the use of a chimera-alkaline phosphatase conjugate demonstrates that enhancement (approximately x 10(5)) in detection sensitivity was obtained with the use of immuno-PCR. Given the enormous amplification capability and specificity of PCR, this immuno-PCR technology has a sensitivity greater than any existing antigen detection system and, in principle, could be applied to the detection of single antigen molecules.

A Leu----His substitution at residue 93 in human corticosteroid binding globulin results in reduced affinity for cortisol

A steroid binding capacity assay and a radioimmunoassay were both used to measure corticosteroid binding globulin (CBG) in serum samples from 22 patients with sepsis. An approximately 50% discordancy between the two values in one patient suggested the presence of a CBG variant with reduced affinity for cortisol, and this was confirmed by Scatchard analysis. We therefore used the polymerase chain reaction to amplify exons that encode for human CBG from the genomic DNA of this patient. This revealed two mutations within the coding sequences: one of which results in a Leu----His substitution at residue 93 and another which encodes a Ser----Ala substitution at residue 224 of the human CBG polypeptide. To assess the impact of each substitution on the steroid binding affinity of CBG, each mutation was introduced separately into a normal human CBG cDNA, and the normal and mutated cDNAs were expressed in Chinese hamster ovary cells. Scatchard analysis of the CBG produced in culture indicated that the His93 mutation (Kd = 2.24 +/- 1.75 nM) reduced the cortisol binding affinity of CBG (mean +/- SD) significantly (P less than 0.024) when compared to normal CBG (Kd = 0.64 +/- 0.31 nM), while the Ala224 mutation (Kd = 0.63 +/- 0.33 nM) did not influence cortisol binding affinity. We therefore conclude that residue 93 may play an important role in determining the structure of the CBG steroid binding site.

Service increment for teaching and research (SIFTR): the Southampton experience

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