Sequence composition similarities with the 7SL RNA are highly predictive of functional genomic features

Transposable elements derived from the 7SL RNA gene, such as Alu elements in primates, have had remarkable success in several mammalian lineages. The results presented here show a broad spectrum of functions for genomic segments that display sequence composition similarities with the 7SL RNA gene. Using thoroughly documented loci, we report that DNaseI-hypersensitive sites can be singled out in large genomic sequences by an assessment of sequence composition similarities with the 7SL RNA gene. We apply a root word frequency approach to illustrate a distinctive relationship between the sequence of the 7SL RNA gene and several classes of functional genomic features that are not presumed to be of transposable origin. Transposable elements that show noticeable similarities with the 7SL sequence include Alu sequences, as expected, but also long terminal repeats and the 5′-untranslated regions of long interspersed repetitive elements. In sequences masked for repeated elements, we find, when using the 7SL RNA gene as query sequence, distinctive similarities with promoters, exons and distal gene regulatory regions. The latter being the most notoriously difficult to detect, this approach may be useful for finding genomic segments that have regulatory functions and that may have escaped detection by existing methods.     

Cryotolerance and Cold Adaptation in Lactococcus lactis Subsp. lactis IL1403

The physiology of the cold-shock response in Lactococcus lactis subsp. lactis IL1403 at a subzero temperature, and cold-induced adaptation to heat shock, were investigated. Preincubation of cells at 8°C led to the development of cryotolerance, i.e., an enhanced capacity to survive exposure to freezing temperature (-20°C). Pretreatment with chemicals considered to be chaotropic agents did not induce cryotolerance or, in contrast, led to a decrease in survival capacity at -20°C. Interestingly, preincubation at 8°C led also to thermololerance to a 52°C challenge, but preincubation of cells at 42°C for 30 min did not improve their capacity to survive freezing-thawing exposure. These results demonstrate that cold- and heat-shock responses are physiologically linked by a complex relation. Furthermore, food processing at low temperature before subzero or heat treatment may need to be reconsidered.     

Ability of a T-antigen transport-defective mutant of simian virus 40 to immortalize primary cells and to complement polyomavirus middle T in tumorigenesis.

The oncogenic potential of polyomavirus in newborn rats could not be expressed by a genome encoding only the middle T antigen but required the presence of one of the other two viral early genes, small T or large T. The tumorigenicity defect could also be complemented by other viral or cellular genes that are known to be implicated in immortalization and establishment functions. The simian virus 40(cT)-3 mutant (R. E. Lanford and J. S. Butel, Cell 37:801-813, 1984), which fails to localize to the nucleus, has the capacity to complement polyomavirus middle T in tumorigenesis and to immortalize primary rat embryo fibroblasts when it was cotransfected in the presence of pSV2-neo. Our data suggested that under the conditions of DNA-mediated tumor induction and cotransfection with a dominant selection marker, the cellular alterations achieved by nonnuclear oncogenes such as polyomavirus small T and simian virus 40(cT)-3 were sufficient to complement polyomavirus middle T in transformation and tumorigenesis.     

Effect of pH on binding of agonists and antagonists to rat heart muscarinic receptors.

Insulin, epidermal growth factor (EGF), platelet-derived growth factor, multiplication-stimulating activity and 10% foetal-calf serum each stimulated the phosphorylation of a cytosolic Mr-22000 acidic heat-stable protein in Swiss mouse 3T3-L1 adipocytes. Phosphorylation of this protein was not stimulated by isoprenaline or dibutyryl cyclic AMP. The effect of insulin was maximal (3-fold increase) by 10 min; half-maximal stimulation was observed at 70 pM-insulin. Both [32P]phosphoserine and [32P]phosphothreonine residues were present in the Mr-22000 protein after insulin- and growth-factor-stimulated phosphorylation, but no [32P]phosphotyrosine. The major site of insulin- and EGF-stimulated phosphorylation appeared to be a threonine residue, in contrast with previously studied insulin-stimulated phosphorylation of serine residues. Insulin treatment appeared to result in a shift of the protein toward the anode on isoelectric focusing. Insulin and EGF present simultaneously did not lead to phosphorylation beyond that seen with each hormone singly. We surmise that insulin, EGF and perhaps other growth factors may activate a common protein kinase or inhibit a common protein phosphatase in 3T3-L1 adipocytes which acts on the Mr-22000 protein.     

Starvation-Induced Stress Resistance in Lactococcus lactis subsp. lactis IL1403

Carbohydrate-starved cultures of Lactococcus lactis subsp. lactis IL1403 showed enhanced resistance to heat, ethanol, acid, osmotic, and oxidative stresses. This cross-protection seems to be established progressively during the transitional growth phase, with maximum resistance occurring when cells enter the stationary phase. Chloramphenicol or rifamycin treatment does not abolish the development of a tolerant cell state but, on the contrary, seems to provoke this response in L. lactis subsp. lactis.     

Barley pathogenesis-related proteins with fungal cell wall lytic activity inhibit the growth of yeasts.

Proteins from intercellular fluid extracts of chemically stressed barley (Hordeum vulgare L.) leaves were separated by native polyacrylamide gel electrophoresis at alkaline or acid pH. Polyacrylamide gels contained Saccharomyces cerevisiae (bakers' yeast) or Schizosaccharomyces pombe (fission yeast) crude cell walls for assaying yeast wall lysis. In parallel, gels were overlaid with a suspension of yeasts for assaying growth inhibition by pathogenesis-related proteins. The same assays were also performed with proteins separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under nonreducing conditions. In alkaline native polyacrylamide gels, only one band corresponding to yeast cell wall lytic activity was found to be inhibitory to bakers' yeast growth, whereas in acidic native polyacrylamide gels one band inhibited the growth of both yeasts. Under denaturing nonreducing conditions, one band of 19 kD inhibited the growth of both fungi. The 19-kD band corresponded to a basic protein after two-dimensional gel analysis. The 19-kD protein with yeast cell wall lytic activity and inhibitory to both yeasts was found to be different from previously reported barley chitosanases that were lytic to fungal spores. It could be different from other previously reported lytic antifungal activities related to pathogenesis-related proteins.     

Characteristics of androgen binding in rat adrenal tissue using [3H]methyltrienolone (R1881) as tracer

A high level of binding of [3H]methyltrienolone (R1881 = 17beta-hydroxy-17alpha-methyl-estra-4, 9, 11-trien-3-one) was found in cytosol prepared from adrenals of castrated male rats. Binding of [3H]R1881 was of high affinity (DK = 6.2 nM) and highly specific for androgens. The [3H]R1881 complex migrates at 7-9S on sucrose gradients in low ionic strength buffer and at 4-5S in buffer containing 0.4M KC1. All binding studies have been performed in parallel with rat ventral prostate and adrenal cytosol. The present data suggest the presence of an androgen binding component in rat adrenal tissue.     

Pathogenesis-related acidic beta-1,3-glucanase genes of tobacco are regulated by both stress and developmental signals

Three pathogenesis-related (PR) proteins of tobacco are acidic isoforms of beta-1,3-glucanase (PR-2a, -2b, -2c). We have cloned and sequenced a partial cDNA clone (lambda FJ1) corresponding to one of the PR-2 beta-1,3-glucanases. A small gene family encodes the PR-2 proteins in tobacco, and similar genes are present in a number of plant species. We analyzed the stress and developmental regulation of the tobacco PR-2 beta-1,3-glucanases by using northern and western analyses and a new technique to assay enzymatic activity. Stress caused by both thiamine and tobacco mosaic virus (TMV) infection resulted in a dramatic increase in the levels of PR-2 mRNA, protein, and enzyme activities. The increased PR-2 gene expression in upper uninoculated leaves of plants infected with TMV also suggests a role in systemic acquired resistance. During floral development, a number of beta-1,3-glucanase activities were observed in all flower tissues. However, PR-2 polypeptides were observed only in sepal tissue. In contrast, an mRNA that hybridized to the PR-2 cDNA was present in stigma/style tissue and the sepals. Primer extension analysis confirmed the identity of the PR-2 mRNA in sepals, but indicated that the beta-1,3-glucanase gene expressed in the stigma/style of flowers was distinct from the PR-2 genes. The induction of PR-2 protein synthesis by both stress and developmental signals was accompanied by a corresponding increase in the steady-state levels of PR-2 mRNA, suggesting that PR-2 gene expression is regulated, in part, at the level of mRNA accumulation.     

Specific progesterone receptors in dimethylbenzanthracene (DMBA)-induced mammary tumors.

Properties of a progesterone receptor present in the cytosol (105,000 xg supernatant) of dimethylbenzanthracene (DMBA)-induced mammary tumors were studied using the highly potent progestin [3H]R 5020 (17, 21-dimethyl-19-nor-pregna-4, 9-diene-3,20-dione). As shown by sucrose gradient analysis, specific binding of [3H] R 5020 is associated with components migrating at 7-8S and 4S. Low affinity binding of the synthetic progestin is eliminated by treatment with dextran-coated charcoal. [3H] R 5020 binding is highly progestin-specific since it is easily displaced by unlabelled norgestrel, R 5020 and progesterone while estradiol-17beta, dihydrotestosterone, testosterone, testosterone and diethylstilbestrol have much lower activity. Dexamethasone and cortisol have little, if any, effect on [3H] R 5020 binding.     

Angiogenic Properties of Human Dental Pulp Stem Cells

Angiogenesis, the formation of capillaries from pre-existing blood vessels, is a key process in tissue engineering. If blood supply cannot be established rapidly, there is insufficient oxygen and nutrient transport and necrosis of the implanted tissue will occur. Recent studies indicate that the human dental pulp contains precursor cells, named dental pulp stem cells (hDPSC) that show self-renewal and multilineage differentiation capacity. Since these cells can be easily isolated, cultured and cryopreserved, they represent an attractive stem cell source for tissue engineering. Until now, only little is known about the angiogenic abilities and mechanisms of the hDPSC. In this study, the angiogenic profile of both cell lysates and conditioned medium of hDPSC was determined by means of an antibody array. Numerous pro-and anti-angiogenic factors such as vascular endothelial growth factor (VEGF), monocyte chemotactic protein-1 (MCP-1), plasminogen activator inhibitor-1 (PAI-1) and endostatin were found both at the mRNA and protein level. hDPSC had no influence on the proliferation of the human microvascular endothelial cells (HMEC-1), but were able to significantly induce HMEC-1 migration in vitro. Addition of the PI3K-inhibitor {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002 and the MEK-inhibitor U0126 to the HMEC-1 inhibited this effect, suggesting that both Akt and ERK pathways are involved in hDPSC-mediated HMEC-1 migration. Antibodies against VEGF also abolished the chemotactic actions of hDPSC. Furthermore, in the chicken chorioallantoic membrane (CAM) assay, hDPSC were able to significantly induce blood vessel formation. In conclusion, hDPSC have the ability to induce angiogenesis, meaning that this stem cell population has a great clinical potential, not only for tissue engineering but also for the treatment of chronic wounds, stroke and myocardial infarctions.