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Results for “Phenotype modifier”

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PubMed2007

Interactive effects of leaf damage, light intensity and support availability on chemical defenses and morphology of a twining vine.

In a greenhouse study, we evaluated the effect of the light environment and support availability on the induction of tropane alkaloids (TAs) after leaf damage in the twining vine Convolvulus arvensis. We also tested whether leaf damage modifies the phenotypic responses of the plant to shade and physical support. We found a consistent pattern of induction of TAs after leaf damage in each environmental condition. The induction of TAs was differentially affected by combinations of support and light treatments. In the sun, prostrate and climbing vines exhibited similar induced responses. In the shade, prostrate vines showed greater induced responses. Thus, vines showed the greatest chemical induction when damage occurred in a resource-poor environment (shade), and there was no cue (support) of future increase in resource uptake. Damaged plants showed reduced plasticity to shading in leaf shape and internodes and petiole length in comparison with control, undamaged plants. Herbivory and/or induced responses to herbivory may limit adaptive plant responses to the environment. Therefore, the negative consequences of herbivory on plant fitness might be magnified in a context of changing environments.

Convolvulus↗
PubMed1985

Influence of neurons on the occurrence of fibre types and myosin light chains in cultured presumptive slow and fast myoblasts.

Myoblasts from 9-day-old quail embryo slow anterior latissimus dorsi (ALD) and fast posterior and latissimus dorsi (PLD) muscles were co-cultured with neurons. The presence of neurons allowed ALD-derived muscle fibres to express characteristic features of a slow muscle (occurrence of alpha' and of beta' fibres and predominance of slow myosin light chains). On the contrary, PLD-derived fibres did not differentiate into normal fast fibres (occurrence of alpha'-like fibres and absence of LC3f). These results are compared with the differentiation of ALD and PLD myoblasts in aneural condition. It is suggested that neurons can modify some phenotypic expression of presumptive slow or fast myoblasts.

Adenosine Triphosphatases↗
PubMed1994

An interleukin 2/sodium butyrate combination as immunotherapy for rat colon cancer peritoneal carcinomatosis.

BACKGROUND/AIMS: Immunotherapy using interleukin 2 has had disappointing results in the treatment of colon cancer. Overcoming escape mechanisms, such as lack of antigen presentation and absence of accessory adhesion molecules on cancer cells, may increase its efficiency. We tried to do so by modifying the phenotype of the weakly immunogenic rat colon cancer PROb cells with sodium butyrate. METHODS: After in vitro treatment with butyrate, PROb cells were tested for lymphokine-activated killer cell sensitivity and, using cytofluorometry, expression of adhesion molecules. We then treated established PROb peritoneal carcinomatoses with intraperitoneal injections of interleukin 2 and butyrate. Tumors were studied histologically and immunohistochemically. We tested the specificity of the immune protection by subsequent subcutaneous challenges with either PROb or glioma cells and by Winn's assay. RESULTS: Butyrate increased lymphokine-activated killer cell sensitivity and expression of major histocompatibility complex class I and intercellular adhesion molecule 1 in vitro. Interleukin 2/butyrate combination resulted in cases of complete cure of carcinomatosis with specific protection against PROb cells. We noticed a complex stroma reaction with numerous functional antigen presenting cells close to PROb cells. CONCLUSIONS: The complete regression of tumor masses may be attributed, at least in part, to a butyrate-induced increase in immunogenicity of the cancer cells. This new combined immunotherapy may be of interest in the treatment of colon cancer.

Adenocarcinoma↗
PubMed1992

Changes in epithelial cells in Hirudo medicinalis during wound healing.

In the leech, Hirudo medicinalis, reepithelialization is an event which takes place early in the wound healing process, immediately after the formation of the pseudoblastema, 4-8 hr postinjury. Epithelial cells on the wound margins move into the wound, modifying their phenotypic characteristics. Cells lose their columnar shape and become flattened. Dermal junctions disrupt and tonofilaments regroup around the nucleus. Then, the epithelial cell sheet moves over the newly formed pseudoblastema by extending filopodia, formed by the cells on the edge, following the so-called "sliding model." When the wound is fully covered by the new epithelium, about 24 hr postinjury, a reorganization of the cytoskeleton occurs and the basal dermal junctions are reconstructed. Six days postinjury, the epidermal cells return to their original columnar shape.

Animals↗
PubMed1990

Interactions of epidermal cells and T cells in inflammatory skin diseases.

Multiple cell types and their factors and cytokines are involved in regulating the immune response in inflammatory skin diseases. Stimulatory and inhibitory factors interact to determine whether the immune response is regulated up or down. Normally, stimulatory signals are counteracted by inhibitory signals to prevent an immune reaction from being initiated. However, exogenous antigens and irritants or endogenous factors and altered immunogenic self-peptides can upset this balance. When that occurs, T cells are activated and an inflammatory skin reaction develops. Lymphokines released from such activated T cells can modify the phenotype and function of normal keratinocytes. They can induce the expression of adhesion molecules and receptors involved in antigen presentation. Furthermore, they can also stimulate keratinocyte proliferation. This may be important in development of the hyperplasia seen in inflammatory skin diseases, especially in psoriasis. Cytokines released from the activated keratinocytes can both stimulate and attract T cells to the epidermis and thereby continue the ongoing immune reaction.

Dermatitis↗
PubMed1991

Phage resistance and altered growth habit in a strain of Streptococcus bovis.

Bacteriophage (phi Sb01) of Streptococcus bovis, isolated from pooled rumen fluid of cattle, was a small siphovirus of morphotype B1. It contained double-stranded DNA of length 30.9 kb, which was digested by the restriction endonucleases, EcoRI, HindIII, and PvuII. Bacteria which survived phi Sb01 infection (strain 2BAr) grew in long chains (100-200 cells), ultimately forming large clumps of cells. This growth habit was in distinct contrast to that of the parent host strain which grew predominantly in the form of single cells or diplococci. Strain 2BAr was genetically stable, resistant to phi Sb01 attack, and the observed differences in the growth characteristics of the parent strain and 2BAr indicated that cells of 2BAr were more adherent. In the rumen ecosystem, the selection of phage-resistant bacteria with altered growth characteristics may be a factor in modifying bacterial phenotypes, and thus increasing variability among bacteria which are closely related genetically.

Animals↗
PubMed1985

Molecular characterisation of the Stc- mutation of Escherichia coli K-12.

The previously described Stc- (suppressor of TolC) mutation modifies the phenotype of tolC mutants from OmpF- to OmpF+. Restriction mapping of chromosomal DNA from Stc+ and Stc- strains was performed to investigate the nature of the mutation which was shown to be a deletion, upstream of the ompC gene. DNA from the region of the deletion was cloned into pUC18 and a 650-bp PstI-EcoRI fragment was sequenced. The deletion started 49 bp upstream of the AUG start codon of the ompC gene, thus removing part of the ompC promoter and the whole of the micF gene. We suggest that the deletion of micF gives rise to the Stc- phenotype since the effect of micF expression is assumed to reduce ompF expression, and the Stc- phenotype involves increase in ompF expression.

Bacterial Outer Membrane Proteins↗
PubMed1984

Estimation of creatine kinase isoenzymes: the effects of caffeine and retinoic acid on CK levels in fetal mouse limbs.

Caffeine and retinoic acid were examined for effects upon limb morphogenesis and upon creatine kinase (CK) as a measure of limb myogenesis. Caffeine at 200 mg/kg, i.p., on E11 produced a low level of forelimb (1.2%) and hindlimb (2.0%) defects. Retinoic acid, at 50 mg/kg given orally as an oily suspension, induced a high level of reduction deformities. Hindlimbs (100%) were affected more than forelimbs (88%). Limbs (E16) were examined for CK isoenzymes using DEAE-Sephacel column chromatography. Untreated limbs had 88.04% skeletal muscle (MM), 6.98% hybrid (MB) and 5.08% brain (BB) CK isoenzyme. Caffeine had no effect. However, retinoic acid increased MM-CK to 92.67%, and decreased BB-CK to 2.24%. This is the first evidence that suggests that retinoic acid may modify the phenotypic expression of developing muscle.

Animals↗
PubMedDate not supplied

Expression of interleukin-1 alpha and beta in early passage fibroblasts from aging individuals.

Human diploid fibroblasts (HDFs) from newborn foreskin constitutively express interleukin-1 (IL-1) mRNA and protein after completing at least 70% (approximately 40 population doublings) of their in vitro life span. This IL-1 in turn induces the synthesis of specific proteins in aging HDFs. To determine whether IL-1 expression may be promoted by in vivo aging, we analyzed the expression of IL-1 and of inducible mRNAs in HDFs from two normal individuals 55 and 92 years old and in HDFs from a patient with premature aging caused by Werner's syndrome. By reverse transcription polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA), we detected expression of IL-1 alpha and beta mRNA and protein in early passage HDFs from both normal individuals and the Werner's syndrome patient. These HDFs also expressed the IL-1-inducible mRNAs for stromelysin, plasminogen activator inhibitor type 2, manganous superoxide dismutase, and collagenase. These results suggest that an age-dependent expression of IL-1 occurs either in vivo or after a few cell divisions in vitro. Therefore, the fibroblast phenotype is modified by the expression of IL-1-inducible genes during aging.

Aged↗
PubMed1994

The spitz gene is required for photoreceptor determination in the Drosophila eye where it interacts with the EGF receptor.

Little is known about the mechanisms by which photoreceptors other than R7 are determined during Drosophila eye development. By looking for mutations that modify the phenotype caused by ectopic expression of the rhomboid gene in the eye, I have discovered that the spitz gene is required for photoreceptor determination. Mosaic analysis suggests that spitz, which encodes a TGF alpha homologue, produces a diffusible signal during ommatidial development. Other members of the spitz group and the EGF receptor also interact with sev-rho, in a pattern that suggests a model in which rhomboid can act as a mediator of a ligand-receptor interaction between spitz and Egfr in the developing eye. These data suggest that photoreceptors other than R7 use a Ras1 signalling pathway activated by the spitz/Egfr interaction, in a manner analogous to the Ras1 pathway activated by boss/sevenless in photoreceptor R7.

Alleles↗
PubMed2005

Antioxidants and endothelium protection.

The endothelium is a complex organ system that controls the homeostasis of the vasculature by integrating signals between the vascular wall and the vessel lumen. Under physiological conditions, it maintains a normal vascular tone and blood fluidity by elaborating a variety of factors, such as nitric oxide, prostacyclin and endothelin. However, in pathological situations the endothelium can also modify its phenotype facilitating vasoconstriction, inflammation, and thrombotic events. These abnormal responses manifest in different clinical settings, such as hypercholesterolemia, hypertension, diabetes mellitus, and occur in the absence of any morphological change of the vessel. The etiology of these altered endothelial functions is multi-factorial, and the mechanisms underlying them are complex and not yet fully elucidated. Today, there is substantial evidence that many endothelial functions are sensitive to the presence of reactive oxygen species and subsequent oxidative stress. Here, I will review the increasing number of studies showing that exogenous antioxidants can modulate the endothelium-dependent vasodilation responses, the homeostatic endothelium-leukocyte interactions, the balance between pro- and anti-thrombotic properties, and the vascular apoptotic responses. Finally, the non-antioxidant activities of some antioxidant will also be described.

Animals↗
PubMed2005

Chronic inflammation does not appear to modify the homozygous hereditary hemochromatosis phenotype.

The mechanism of excessive iron storage in patients with hereditary hemochromatosis caused by mutations of the HFE gene seems to be a failure to up-regulate hepcidin in the face of increased body iron. Since the cytokines IL-1 and IL-6 stimulate hepcidin transcription in the absence of HFE, chronic inflammatory states might counteract the effect of HFE mutations. We measured the pre-phlebotomy plasma levels of C reactive protein (CRP) and of interleukin 6 (IL-6) in homozygotes for the C282Y mutation of HFE. There was no difference in these levels in subjects with high iron stores than in those with low iron stores, suggesting that the phenotypic differences between such homozygotes is not appreciably affected by ongoing chronic inflammation.

C-Reactive Protein↗
PubMed2006

Helicobacter pylori infection and HFE hemochromatosis.

Helicobacter pylori infections are associated with iron deficiency, even in the absence of bleeding. To determine whether H. pylori infection plays a role in modifying the phenotype of patients homozygous for the c.845 G > A (C282Y) mutation of the HFE gene we studied 79 homozygous women and 76 homozygous men, comparing the pretreatment hemoglobin, MCV, serum ferritin, transferrin saturation of those who were seropositive and seronegative for H. pylori. No difference between seropositive and seronegative homozytoes was found. There was also no difference between seropositive and seronegative control subjects. We also compared the total iron of 56 of the male and 32 of the female homozygotes as determined by serial phlebotomy. No significant difference was found.

Female↗
PubMedDate not supplied

Reciprocal regulation of permeability through a cultured keratinocyte sheet by IFN-gamma and IL-4.

The T cell cytokines profoundly modify the phenotypic and functional characteristics of keratinocytes. Until now, no study has focused on the effect of Th1 and Th2 cytokines on keratinocyte permeability. Using a two-layer well culturing system, permeability was assessed through cultured keratinocyte sheet in the presence or absence of various concentrations of IFN-gamma and IL-4. Transepithelial electrical resistance (TER) and the flux of 40 kDa FITC-dextrans were measured across the cultured keratinocyte sheet. IFN-gamma significantly increased the TER in a dose- and time-dependent manner, suggesting that IFN-gamma profoundly inhibited the permeability of ions through the keratinocyte sheet. In contrast, IL-4 did not affect the TER. When compared to medium control, the flux of FITC-dextran of the IFN-gamma group was significantly decreased in a dose-dependent fashion. In sharp contrast, the flux of FITC-dextran was significantly and dose-dependently increased in the presence of IL-4. A significant increase in TER and a significant decrease in the flux of dextran suggested that IFN-gamma clearly reduced the permeability of both ions and high molecular weight material through the keratinocyte sheet. Although IL-4 did not affect the permeability of the ions, it significantly enhanced the permeability of high molecular weight material. A flow cytometric assay revealed that the expression of desmoglein-3 was suppressed by IL-4, but was enhanced by IFN-gamma. The reciprocal regulation of permeability of the cultured keratinocyte sheet by IFN-gamma and IL-4 may be partly related to the modification of intercellular adhesion molecules.

Cell Line↗
PubMed2005

Darkness induced neuroplastic changes in the serotoninergic system of the chick retina.

Sensory experience is critical for the formation of neuronal circuits and it is well known that neuronal activity plays a crucial role in the formation and maintenance of synapses. In the vertebrate retina, exposure to different environmental conditions results in structural, physiological, neurochemical and pharmacological changes. Serotoninergic (5HT) amacrine cells of the chicken retina are bistratified interneurons whose primary dendrites descend through the inner nuclear layer (INL) to branch in the inner plexiform layer (IPL) forming two plexi, an outer network, localized to sublamina 1, and an inner network, localized to sublamina 4 and 5 of the IPL. Their development is temporally correlated with the establishment of synapses in the retina and with the emergence of the typical adult electroretinogram. It is unknown, however, which role these cells play in processing visual information and whether visual deprivation modifies their phenotype. Here, we show that, in the chicken, red-light rearing from hatching to postnatal day 12 significantly alters the stratification pattern of 5HT amacrine cells, inhibiting their age-dependent pruning measured with morphometric and densitometric procedures; as well as increasing serotonin immunoreactivity measured as relative optical density. This change in dendritic arborization, accompanied by an increase in serotonin concentration in dark adapted conditions, may decrease visual threshold, thus increasing visual sensitivity.

Age Factors↗
PubMed2003

The human genetics of anorexia nervosa.

Anorexia nervosa is a severe eating disorder characterised by restricted eating, the relentless pursuit of thinness and obsessive fears of being fat. The involved risk factors are probably numerous, but the existence of a genetic vulnerability has been proposed for decades. The heritability in the broad sense is computed on the basis of aggregation studies, treated twin samples and twin studies from the general population. Many difficulties make this heritability estimation problematic, but the convergence of the results (from family studies and two types of twin studies) gives the most convincing evidence in favour of a major role of genetics in the vulnerability to anorexia nervosa, with a heritability around 70%. Regarding the analysis of candidate genes, the most frequently studied is the 5-HT(2A) gene, with positive and negative results. We thus propose a meta-analysis showing that a large heterogeneity between samples exists, but the main effect of the -1438A allele persists even when extracting this contaminating effect (p=0.003). Furthermore, the absence of significant correlation between odds ratio and time after first publication of each sample, and size of each sample, is in accordance with the fact that the A allele is a risk factor. In order to explain the high heterogeneity between the nine studies yet performed, an alternative explanation such as a "modifying the phenotype" effect is proposed.

Anorexia Nervosa↗
PubMed2004

The local physicochemical environment conditions the proinflammatory response of endothelial cells and thus modulates leukocyte recruitment.

The locations at which vascular endothelial cells recruit leukocytes during physiological or pathological inflammatory responses are influenced by direct effects of local haemodynamics on leukocyte adhesion. However, the expression of genes by endothelial cells, and their ability to respond to inflammatory cytokines also depend on the flow forces to which they are exposed. In addition, cells of the underlying stroma can modify the phenotype and responsiveness of endothelial cells, and hence their ability to recruit leukocytes. Thus, endothelial cells are plastic in their responses, and we hypothesise that the pattern of recruitment of leukocytes to tissues is critically dependent on the variable modulation of the endothelium by the local physicochemical microenvironment.

Animals↗