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1.
Nature ; 573(7775): 573-577, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31527826

RESUMO

It has long been suggested that climate shapes land surface topography through interactions between rainfall, runoff and erosion in drainage basins1-4. The longitudinal profile of a river (elevation versus distance downstream) is a key morphological attribute that reflects the history of drainage basin evolution, so its form should be diagnostic of the regional expression of climate and its interaction with the land surface5-9. However, both detecting climatic signatures in longitudinal profiles and deciphering the climatic mechanisms of their development have been challenging, owing to the lack of relevant global data and to the variable effects of tectonics, lithology, land surface properties and human activities10,11. Here we present a global dataset of 333,502 river longitudinal profiles, and use it to explore differences in overall profile shape (concavity) across climate zones. We show that river profiles are systematically straighter with increasing aridity. Through simple numerical modelling, we demonstrate that these global patterns in longitudinal profile shape can be explained by hydrological controls that reflect rainfall-runoff regimes in different climate zones. The most important of these is the downstream rate of change in streamflow, independent of the area of the drainage basin. Our results illustrate that river topography expresses a signature of aridity, suggesting that climate is a first-order control on the evolution of the drainage basin.


Assuntos
Clima , Modelos Teóricos , Rios , Hidrologia
3.
Science ; 203(4383): 907-10, 1979 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-17771730

RESUMO

Changes in the ground elevation observed before and immediately after the 1971 San Fernando, California, earthquake are consistent with a theoretical model in which fault zone rocks are strain-softening after peak stress. The model implies that the slip rate of the fault increased to aboul 0.1 meter per year near the focus before the earthquake.

4.
J Clin Invest ; 106(9): 1105-13, 2000 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-11067863

RESUMO

Apolipoprotein J/clusterin (apoJ/clusterin), an intriguing protein with unknown function, is induced in myocarditis and numerous other inflammatory injuries. To test its ability to modify myosin-induced autoimmune myocarditis, we generated apoJ-deficient mice. ApoJ-deficient and wild-type mice exhibited similar initial onset of myocarditis, as evidenced by the induction of two early markers of the T cell-mediated immune response, MHC-II and TNF receptor p55. Furthermore, autoantibodies against the primary antigen cardiac myosin were induced to the same extent. Although the same proportion of challenged animals exhibited some degree of inflammatory infiltrate, inflammation was more severe in apoJ-deficient animals. Inflammatory lesions were more diffuse and extensive in apoJ-deficient mice, particularly in females. In marked contrast to wild-type animals, the development of a strong generalized secondary response against cardiac antigens in apoJ-deficient mice was predictive of severe myocarditis. Wild-type mice with a strong Ab response to secondary antigens appeared to be protected from severe inflammation. After resolution of inflammation, apoJ-deficient, but not wild-type, mice exhibited cardiac function impairment and severe myocardial scarring. These results suggest that apoJ limits progression of autoimmune myocarditis and protects the heart from postinflammatory tissue destruction.


Assuntos
Doenças Autoimunes/etiologia , Glicoproteínas/fisiologia , Chaperonas Moleculares , Miocardite/etiologia , Animais , Antígenos CD/biossíntese , Autoanticorpos/biossíntese , Doenças Autoimunes/imunologia , Doenças Autoimunes/patologia , Sequência de Bases , Clusterina , Primers do DNA/genética , Feminino , Glicoproteínas/deficiência , Glicoproteínas/genética , Antígenos de Histocompatibilidade Classe II/biossíntese , Masculino , Camundongos , Camundongos Knockout , Miocardite/imunologia , Miocardite/patologia , Miosinas/imunologia , Receptores do Fator de Necrose Tumoral/biossíntese , Receptores Tipo I de Fatores de Necrose Tumoral , Linfócitos T/imunologia
5.
Sci Rep ; 6: 34438, 2016 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-27688039

RESUMO

Shallow landslides, triggered by extreme rainfall, are a significant hazard in mountainous landscapes. The hazard posed by shallow landslides depends on the availability and strength of colluvial material in landslide source areas and the frequency and intensity of extreme rainfall events. Here we investigate how the time taken to accumulate colluvium affects landslide triggering rate in the Southern Appalachian Mountains, USA and how this may affect future landslide hazards. We calculated the failure potential of 283 hollows by comparing colluvium depths to the minimum (critical) soil depth required for landslide initiation in each hollow. Our data show that most hollow soil depths are close to their critical depth, with 62% of hollows having soils that are too thin to fail. Our results, supported by numerical modeling, reveal that landslide frequency in many humid landscapes may be insensitive to projected changes in the frequency of intense rainfall events.

6.
Biochim Biophys Acta ; 1082(1): 85-93, 1991 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-2009304

RESUMO

Isoforms of porcine pancreatic phospholipase A2 (PLA2) can be differentially regulated by heparin. The major isoform of PLA2 can bind to heparin-Affigel and its catalytic activity can be inhibited by heparin. The interaction between this PLA2 isoform and heparin does not require calcium ion or a functional active site. The sensitivity to heparin inhibition depends on the pH, with optimum sensitivity at pH 5-7 and greatly diminished sensitivity as the pH is increased from 7 to 10. A minor isoform of porcine pancreatic PLA2 cannot bind to heparin and is resistant to heparin inhibition. The resistant isoform appears to be iso-pig PLA2. Heparin affinity chromatography therefore offers a convenient route to the isolation of structurally and functionally distinct classes of PLA2 enzymes. The existence of classes of PLA2 that can be differentially regulated by heparin may have important physiological consequences.


Assuntos
Heparina/farmacologia , Isoenzimas/metabolismo , Pâncreas/enzimologia , Fosfolipases A/metabolismo , Sequência de Aminoácidos , Animais , Cromatografia de Afinidade , Eletroforese em Gel de Poliacrilamida , Heparina/metabolismo , Concentração de Íons de Hidrogênio , Isoenzimas/antagonistas & inibidores , Isoenzimas/química , Dados de Sequência Molecular , Peso Molecular , Fragmentos de Peptídeos/química , Mapeamento de Peptídeos , Fosfolipases A/antagonistas & inibidores , Fosfolipases A/química , Fosfolipases A2 , Conformação Proteica , Suínos
7.
Arch Dermatol ; 134(7): 813-8, 1998 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-9681344

RESUMO

OBJECTIVES: To determine the cellular localization in male and female axillary tissue for apocrine secretion odor-binding proteins 1 (ASOB1) and 2 (ASOB2) and the electrophoretic pattern of female apocrine proteins and to begin characterization of the ASOB1 protein. DESIGN: Immunohistochemical techniques were used with biopsy samples from axillary tissue of male and female subjects. Immunological techniques and microsequencing were used to characterize several of the proteins in male and female apocrine secretions. SETTING: A university medical center. PARTICIPANTS: Healthy male and female volunteers who donated apocrine secretions and/or axillary tissue. RESULTS: Specific immunoreactivity was localized only to the apocrine glands in both sexes. Furthermore, only preabsorption with a mixed apocrine secretion sample eliminated all immunoreactivity. The electrophoretic pattern of proteins in female apocrine secretions is similar to that in male secretions. Western blotting of the separated proteins from female samples using serum samples containing antibodies to ASOB1 and ASOB2 yielded identical results to those found with separated proteins from male samples. Partial sequence data obtained from the N-terminus of ASOB1 suggested that it shares homology with the alpha-chain of apolipoprotein J (Apo J). Apocrine secretion odor-binding protein 1 is not immunologically similar to ApoJ, but 2 other apocrine secretion proteins are. CONCLUSIONS: Male and female subjects appear to have the same glycoprotein carriers for (E)-3-methyl-2-hexenoic acid localized to the apocrine glands. The N-terminal sequence for ASOB1 may be homologous to Apo J, but it is not immunologically similar to it. However, 2 other proteins in the apocrine secretion appear to be the monomer and dimer forms of Apo J.


Assuntos
Glândulas Apócrinas/metabolismo , Chaperonas Moleculares , Odorantes/análise , Precursores de Proteínas/análise , Receptores Odorantes/análise , Adulto , Sequência de Aminoácidos , Anticorpos/sangue , Glândulas Apócrinas/química , Glândulas Apócrinas/imunologia , Axila , Western Blotting , Clusterina , Feminino , Glicoproteínas/química , Glicoproteínas/imunologia , Humanos , Imuno-Histoquímica , Masculino , Dados de Sequência Molecular , Fragmentos de Peptídeos/química , Precursores de Proteínas/química , Receptores Odorantes/química , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Fatores Sexuais
8.
Med Hypotheses ; 3(6): 221-5, 1977.
Artigo em Inglês | MEDLINE | ID: mdl-593181

RESUMO

A great number of experimental studies have now been performed with malignant cells. The mass of data generated presents a confusing and often apparently contradictory picture of the fundamental molecular biological defect which most scientists sense must be the cause of transformation of a normal cell into a malignant one. This paper proposes the hypothesis that RNA on the exterior of the cell membrane organizes the various functional molecular aggregates such as transport complexes (permeases), lectin receptor sites, transmembrane microfilament attachment sites, hormone receptor complexes, and the elusive contact inhibition components. Furthermore it is proposed that a defect in the production of or competition for the assembly of exterior-organizer RNA (exoRNA) complexes is the primary molecular defect inherent in all malignancies. The defect could be caused by deletion of a chromosome region producing or controlling exoRNA, mutation of the genes involved in exoRNA production or by insertion of viral genetic material into the genome thereby producing an incomplete viral RNA (vRNA) which competes for exoRNA binding sites in cell surface complexes. Such changes would be genetically transmitted and could represent a range of genetic change between chromosomal deletion and point mutation. Several experiments are suggested to directly test the hypothesis.


Assuntos
Membrana Celular/metabolismo , Transformação Celular Viral , Neoplasias/metabolismo , RNA Neoplásico/metabolismo , Transporte Biológico , Inibição de Contato , Genes Virais , Mutação , Neoplasias/genética , RNA Viral/metabolismo
11.
Genome ; 34(4): 644-51, 1991 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-1838345

RESUMO

The gene product of the mtr locus of Neurospora crassa is required for the transport of neutral aliphatic and aromatic amino acids via the N system. We have previously cloned three cosmids containing Neurospora DNA that complement the mtr-6(r) mutant allele. The cloned DNAs were tightly linked to restriction fragment length polymorphisms that flank the mtr locus. A 2.9-kbp fragment from one cosmid was subcloned and found to complement the mtr-6(r) allele. Here we report the sequence of the fragment that hybridized to a poly(A)+ mRNA transcript of about 2300 nucleotides. We have identified an 845-bp open reading frame (ORF) having a 59-bp intron as the potential mtr ORF. S1 nuclease analysis of the transcript confirmed the transcript size and the presence of the intron. A second open reading frame was found upstream in the same reading frame as the mtr ORF and appears to be present in the mRNA transcript. The mtr ORF is predicted to encode a 261 amino acid polypeptide with a molecular mass of 28 613 Da. The proposed polypeptide exhibits six potential alpha-helical transmembrane domains with an average length of 23 amino acids, does not have a signal sequence, and contains amino acid sequence homologous to an RNA binding motif.


Assuntos
Sistemas de Transporte de Aminoácidos Neutros , Aminoácidos/metabolismo , Proteínas Fúngicas/genética , Genes Fúngicos , Proteínas de Membrana/genética , Neurospora crassa/genética , Sequência de Aminoácidos , Sequência de Bases , Códon , DNA Fúngico , Dados de Sequência Molecular , Neurospora crassa/metabolismo , Fases de Leitura Aberta , Biossíntese de Proteínas , Sequências Reguladoras de Ácido Nucleico , Homologia de Sequência do Ácido Nucleico , Transcrição Gênica
12.
Biochem Genet ; 21(5-6): 443-52, 1983 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-6870772

RESUMO

This report describes a method to isolate temperature-conditional phenylalanine transport mutants from the transformed human cell line HeLa. Using ultraviolet light as a mutagenic agent and DL-parafluorophenylalanine (PFPA), a poisonous analogue of L-phenylalanine, as a selective agent, mutagenized cells were selected for survival in the presence of PFPA at a temperature of 39 degrees C. Survivors of the mutagenesis and selection procedures were removed from the culture dishes by trypsin and cloned at a temperature of 35 degrees C. Seven of these lines isolated demonstrated continued resistance to PFPA at 39 degrees C. These lines were tested for uptake of L-phenylalanine at an external concentration of 100 microM and for continued resistance to PFPA at two concentrations. Cells were tested at 35 and at 39 degrees C. The data were compared to those obtained for the parental HeLa cell line under identical conditions. The seven mutant cell lines demonstrated varying resistances to PFPA and varying levels of accumulation of L-phenylalanine when tested at 35 and 39 degrees C. Three mutant lines were additionally tested for L-phenylalanine tRNA charging levels and for transport of L-arginine. The lines had parental cell levels of tRNA charging and L-arginine transport which suggest that the induced genetic defect affects a specific L-phenylalanine transport system.


Assuntos
Resistência a Medicamentos , Mutação , Fenilalanina/análogos & derivados , p-Fluorfenilalanina/farmacologia , Células HeLa/efeitos da radiação , Humanos , Temperatura , Raios Ultravioleta
13.
J Bacteriol ; 122(1): 41-6, 1975 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-123524

RESUMO

Incubation of Neurospora crassa conidia with ribonuclease (RNase) A reduces transport of L-phenylalanine by those cells. Under similar conditions, oxidized RNase A, RNase T1, and RNase T2 do not have this effect. Incubation of conidia with active RNase covalently attached to polyacrylamide beads reduces L-phenylalanine transport. This indicates that the site of enzymatic action is at the cell surface. At the lower concentration of enzyme used in this study, incubation with RNase A reduces transport of L-phenylalanine by the general (G) amino acid permease. Increasing the enzyme concentration results in reduction of transport by the neutral aromatic (N)-specific permease. The increased transport activity that accompanies onset of conidial germination is also sensitive to incubation with RNase A. Application of the enzyme to actively transporting cells does not release amino acid transported prior to enzyme addition. Cells cultured on media supplemented with [2-14C] uridine release isotopic activity after RNase A incubation. Analogous treatments with Pronase, RNase T1, RNase T2, or deoxyribonuclease I do not release isotope activity. Pronase treatment does reduce L-phenylalanine transport. Incubation of conidia with RNase A also inhibits germination of those conidia.


Assuntos
Aminoácidos/metabolismo , Neurospora crassa/metabolismo , Neurospora/metabolismo , Ribonucleases/farmacologia , Transporte Biológico Ativo/efeitos dos fármacos , Proteínas de Membrana Transportadoras/metabolismo , Mutação , Neurospora crassa/enzimologia , Neurospora crassa/crescimento & desenvolvimento , Fenilalanina/metabolismo , Pronase/farmacologia , Esporos Fúngicos/crescimento & desenvolvimento , Esporos Fúngicos/metabolismo , Uridina/metabolismo
14.
J Bacteriol ; 129(1): 395-9, 1977 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-137232

RESUMO

Extrinsic ribonucleic acid (RNA) can be isolated from a KCl extract of Neurospora crassa conidial cell surface products. It is heterogeneous in size. The bulk of this RNA travels as a broad band, trailing the 5.8S ribosomal marker RNA on electrophoretic gels. The extrinsic RNA, when denatured, exhibites several discrete lengths between 50,000 and 130,000 daltons. Melting profiles confirm the heterogeneity of the RNA and indicate that 58% of the bases are involved in hydrogen bonding. Analyses of alkaline hydrolysis products reveal no extensive methylation and few or none of the unusual bases present in transfer RNA. The bases are present in approximately equivalent amounts. Extrinsic RNA represents 2 to 3% of the total cellular RNA. Since this membrane-associated class of RNA does not resemble ribosomal RNA, messenger RNA, or transfer RNA and since it is extracted from the cell exterior by methods used to remove extrinsic membrane molecules, we have designated it extrinsic RNA.


Assuntos
Neurospora crassa/análise , Neurospora/análise , RNA/análise , Adenina/análise , Membrana Celular/análise , Citosina/análise , Eletroforese em Gel de Poliacrilamida , Guanina/análise , Metilação , Peso Molecular , Neurospora crassa/ultraestrutura , Desnaturação de Ácido Nucleico , Uracila/análise
15.
Genome ; 30(2): 198-203, 1988 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-2843424

RESUMO

Translocation of neutral aliphatic and aromatic amino acids across the plasma membrane of the ascomycete Neurospora crassa requires a functional gene product of the mtr locus. Mutations at this locus are defective in transport of those amino acids. We have cloned the mtr+ gene of Neurospora crassa from an ordered cosmid library of genomic DNA and produced a preliminary restriction map of 2.9 kilobases of genomic DNA that encompasses the mtr coding region. We have confirmed that the cloned DNA regions contain the mtr gene sequence by restriction fragment length polymorphism mapping and have determined that the cloned sequence codes for a messenger RNA transcript of approximately 1200 nucleotides in length.


Assuntos
Aminoácidos/metabolismo , Clonagem Molecular , Neurospora crassa/genética , Neurospora/genética , Mapeamento Cromossômico , Enzimas de Restrição do DNA/metabolismo , DNA Recombinante/análise , Ligação Genética , Transformação Genética
16.
J Lipid Res ; 33(10): 1517-26, 1992 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-1431576

RESUMO

Apolipoprotein J (apoJ) is a unique glycoprotein thought to be involved in a variety of physiological processes, including lipid transport, regulation of complement function, sperm maturation, programmed cell death, and membrane recycling. In the plasma, apoJ is associated with apoA-I in high and very high density lipoproteins. In this report we demonstrate that HepG2 human hepatocellular carcinoma cells secrete apoJ in association with a significant amount of lipid, providing unequivocal evidence that apoJ can transport lipids. The HepG2 cell line has provided important clues about the structural organization of nascent lipoprotein particles. HepG2 cell apoJ-containing lipoproteins are dense and heterogenous in size, ranging from 100 to 910 kDa. Plasma and HepG2 cell apoJ-lipoproteins differ in size distribution. Both have alpha 2 electrophoretic mobility, although their average mobilities differ within the alpha 2 region. In contrast to plasma apoJ-HDL which contain little triglyceride and which can associate with apoA-I, HepG2 cell apoJ-lipoproteins are rich in triglyceride and lack apoA-I. By implication, nascent apoJ-lipoproteins undergo plasma remodeling that results in triglyceride depletion and apoA-I association. We propose that the metabolic consequences of this remodeling play an important role in lipid homeostasis in localized tissue environments, particularly where organs are isolated from the blood by cellular barriers such as in testis and brain. In such tissues, apoJ is expressed constitutively in high level compared to other lipid transport proteins.


Assuntos
Apolipoproteínas/metabolismo , Glicoproteínas , Lipoproteínas HDL/metabolismo , Fígado/metabolismo , Chaperonas Moleculares , Apolipoproteína A-I/metabolismo , Apolipoproteínas/sangue , Biomarcadores , Radioisótopos de Carbono , Fracionamento Químico , Clusterina , Eletroforese , Humanos , Lipoproteínas HDL/sangue , Células Tumorais Cultivadas
17.
Am J Physiol Endocrinol Metab ; 279(1): E60-7, 2000 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-10893323

RESUMO

In this study, we investigated the mechanisms responsible for the growth-inhibitory action of parathyroid hormone-related protein (PTHRP) in A10 vascular smooth muscle cells (VSMC). Fluorescence-activated cell sorting analysis of serum-stimulated VSMC treated with PTHRP or dibutyryl-cAMP (DBcAMP) demonstrated an enrichment of cells in G1 and a reduction in the S phase. Measurement of DNA synthesis in platelet-derived growth factor-stimulated VSMC treated with DBcAMP revealed that cells became refractory to growth inhibition by 12-16 h, consistent with blockade in mid-G1. cAMP treatment blunted the serum-induced rise in cyclin D1 during cell cycle progression without altering levels of the cyclin-dependent kinase cdk4 or cyclin E and its associated kinase, cdk2. Exposure of cells to PTHRP or cAMP resulted in a reduction in retinoblastoma gene product (Rb) phosphorylation. Immunoblotting of extracts from cAMP-treated cells with antibodies to cdk inhibitors revealed a striking increase in p27(kip1) abundance coincident with the G1 block. Immunoprecipitation with an anti-cyclin D1 antibody of cell lysates prepared from cAMP-treated cells followed by immunoblotting with antisera to p27(kip1) disclosed a threefold increase in p27(kip1) associated with cyclin D1 compared with lysates treated with serum alone. We conclude that PTHRP, by increasing intracellular cAMP, induces VSMC cycle arrest in mid-G1. This occurs secondary to a suppression in cyclin D1 and induction of p27(kip1) expression, which in turn inhibits Rb phosphorylation.


Assuntos
Proteínas de Ciclo Celular , Fase G1/efeitos dos fármacos , Músculo Liso Vascular/citologia , Proteínas/farmacologia , Proteínas Proto-Oncogênicas , Proteínas Supressoras de Tumor , Bucladesina/farmacologia , Divisão Celular/efeitos dos fármacos , Linhagem Celular , AMP Cíclico/fisiologia , Quinase 4 Dependente de Ciclina , Inibidor de Quinase Dependente de Ciclina p27 , Quinases Ciclina-Dependentes/antagonistas & inibidores , Quinases Ciclina-Dependentes/metabolismo , Ciclinas/metabolismo , Inibidores Enzimáticos/metabolismo , Proteínas Associadas aos Microtúbulos/metabolismo , Músculo Liso Vascular/efeitos dos fármacos , Músculo Liso Vascular/metabolismo , Proteína Relacionada ao Hormônio Paratireóideo
18.
J Biol Chem ; 262(36): 17563-71, 1987 Dec 25.
Artigo em Inglês | MEDLINE | ID: mdl-3693366

RESUMO

The lipid transfer protein complex (LTC) isolated from human plasma by immunoaffinity chromatography transfers cholesteryl esters (CE), triglycerides, and phosphatidylcholine (PC) between lipoproteins in vitro. The molecular weight of this lipid transfer catalyst in sodium dodecyl sulfate-polyacrylamide gels was 65,000. When resolved on a gel filtration column by high performance liquid chromatography (HPLC), LTC was composed of fractions of high (greater than 150,000) to low (18,000) molecular weight, although sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of each fraction revealed bands at Mr 65,000 (major) and 52,000 (minor). The CE and triglyceride transfer activity of the low Mr HPLC fraction (1049 nmol of triglyceride/mg/h and 244 nmol of CE/mg/h) was significantly greater than that of the high Mr HPLC fraction (15-27 nmol of triglyceride/mg/h and 20-30 nmol of CE/mg/h). The PC transfer activity of the HPLC fractions was not determined. LTC proteins were separated by dialysis in acidified chloroform:methanol solution into dialysand and dialysate proteins. The dialysate contained a low Mr proteolipid, designated the catalytic domain Cd, which catalyzed CE and triglyceride transfer at equivalent rates (11.0 versus 9.5 mumol/mg/h, respectively). PC transfer activity was approximately 10% of these levels (1.5 mumol/mg/h). The dialysand consisted of a protein, designated the transfer protein TP, which facilitated CE (3.4 mumol/mg/h) preferentially over triglyceride and PC (1.0 mumol/mg/h) transfer, and a catalytically inactive protein, designated the heparin-binding domain Hd. We propose a model of the LTC protein (based on catalytic activities, monoclonal antibody reactivities, and heparin-binding capacities of the isolated proteins) in which both Hd (approximately 13 kDa) and Cd (approximately 3 kDa) originate from a single lipid transfer protein, TP.


Assuntos
Proteínas de Transporte/sangue , Glicoproteínas , Proteolipídeos/sangue , Aminoácidos/análise , Sítios de Ligação , Proteínas de Transferência de Ésteres de Colesterol , Cromatografia Líquida de Alta Pressão , Heparina/metabolismo , Humanos , Concentração de Íons de Hidrogênio , Lipoproteínas/sangue , Peso Molecular , Fosfatidilcolinas/sangue , Triglicerídeos/sangue
19.
Proc Natl Acad Sci U S A ; 92(14): 6612-6, 1995 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-7604041

RESUMO

We have developed a system for the isolation of Neurospora crassa mutants that shows altered responses to blue light. To this end we have used the light-regulated promoter of the albino-3 gene fused to the neutral amino acid permease gene mtr. The product of the mtr gene is required for the uptake of neutral aliphatic and aromatic amino acids, as well as toxic analogs such as p-flurophenylalanine or 4-methyltryptophan. mtr trp-2-carrying cells were transformed with the al-3 promoter-mtr wild-type gene (al-3p-mtr+) to obtain a strain with a light-regulated tryptophan uptake. This strain is sensitive to p-fluorophenylalanine when grown under illumination and resistant when grown in the dark. UV mutagenesis of the al-3p-mtr(+)-carrying strain allowed us to isolate two mutant strains, BLR-1 and BLR-2 (blue light regulator), that are light-resistant to p-fluorophenylalanine and have lost the ability to grow on tryptophan. These two strains have a pale-orange phenotype and show down-regulation of all the photoregulated genes tested (al-3, al-1, con-8, and con-10). Mutations in the BLR strains are not allelic with white collar 1 or white collar 2, regulatory genes that are also involved in the response to blue light.


Assuntos
Proteínas de Transporte/genética , Regulação Fúngica da Expressão Gênica , Genes Fúngicos , Neurospora crassa/genética , Neurospora crassa/metabolismo , Raios Ultravioleta , Sistemas de Transporte de Aminoácidos , Aminoácidos/metabolismo , Sequência de Bases , Northern Blotting , Southern Blotting , Proteínas de Transporte/biossíntese , Quimera , Primers do DNA , DNA Fúngico/análise , Regulação Fúngica da Expressão Gênica/efeitos da radiação , Luz , Dados de Sequência Molecular , Mutagênese , Neurospora crassa/efeitos da radiação , Reação em Cadeia da Polimerase , Regiões Promotoras Genéticas , RNA Mensageiro/análise , RNA Mensageiro/biossíntese
20.
Biochemistry ; 31(36): 8552-9, 1992 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-1390641

RESUMO

Apolipoprotein J (apoJ) defines a heterogeneous subclass of human plasma high-density lipoproteins (HDL) having a bimodal distribution of molecular mass of 70-90 kDa (approximately 50%) and 200 kDa or larger (approximately 50%). ApoJ-HDL are unstable in stored plasma, and must be evaluated within 24 h. All apoJ-HDL in freshly obtained plasma have alpha 2 electrophoretic mobility and are distinct from a minor subpopulation of apoAI-HDL which electrophorese in the pre beta region. Although apoAI is not associated with the majority of plasma apoJ-HDL, a small fraction of these particles also containing apoAI. There is little variation in the apoJ/apoAI mole ratio of apoJ-HDL immunoaffinity purified from the same individual on different days. In addition, there is a constant ratio among individuals, assessed for five volunteers, of 4.9 +/- 0.6. Purified apoJ added directly to apoJ-depleted plasma can interact with apoAI or with apoAI-containing lipoproteins, as evidenced by the association of apoAI with apoJ that is reisolated by immunoaffinity chromatography. The amount of apoAI associated with apoJ increases linearly with increasing amount of apoJ added, over the range of apoJ concentrations tested. No other known apolipoprotein is associated with apoJ. By two-dimensional electrophoretic analysis, the lipoproteins containing both apoJ and apoAI have approximate molecular masses of 350-400 kDa. Taken together, the results suggest that the interaction between apoJ and apoAI is physiologically important and that lipoproteins which contain both apoJ and apoAI can be produced in the plasma. ApoJ-HDL and apoJ/apoAI-HDL may have different functions and metabolic fates or may represent different stages of apoJ catabolism.


Assuntos
Apolipoproteínas/sangue , Glicoproteínas , Lipoproteínas HDL/sangue , Chaperonas Moleculares , Apolipoproteína A-I/análise , Apolipoproteína A-I/isolamento & purificação , Apolipoproteínas/isolamento & purificação , Cromatografia de Afinidade , Clusterina , Eletroforese , Humanos , Lipoproteínas HDL/isolamento & purificação , Masculino , Peso Molecular
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