RESUMO
The pulmonary surfactant proteins SP-B (8,000 D) and SP-C (4,000 D) accelerate surface film formation by surfactant phospholipids. We used cDNA probes to examine regulation of these proteins in human fetal lung. The mRNAs were detectable at 13 wk gestation and increased to approximately 50% (SP-B) and approximately 15% (SP-C) of adult levels at 24 wk. The mRNAs were detected only in lung of 11 dog tissues examined. When human fetal lung was cultured as explants without hormones, SP-B mRNA increased and SP-C mRNA decreased. Exposure for 48 h to glucocorticoids, but not other steroids, increased both SP-B mRNA (approximately 4-fold) and SP-C mRNA (approximately 30-fold) vs. controls. Half-maximal stimulation occurred with 1 nM dexamethasone and 300 nM cortisol for SP-B mRNA and at three- to fivefold higher concentrations for SP-C mRNA. Both stimulation and its reversal on removal of hormone were more rapid for SP-B than for SP-C. Terbutaline and forskolin increased SP-B mRNA but not SP-C mRNA. Levels of both mRNAs were much higher in type II cells than fibroblasts prepared from explants. Thus, the genes for SP-B and SP-C are expressed in vivo before synthesis of both SP-A (28,000-36,000 D) and surfactant lipids. Glucocorticoid induction of SP-B and SP-C mRNAs in type II cells appears to be receptor mediated but may involve different mechanisms.
Assuntos
Pulmão/metabolismo , Surfactantes Pulmonares/metabolismo , RNA Mensageiro/metabolismo , Animais , Northern Blotting , Técnicas de Cultura , AMP Cíclico/fisiologia , Dexametasona/farmacologia , Cães , Epitélio/metabolismo , Fibroblastos , Humanos , Pulmão/efeitos dos fármacos , RNA Mensageiro/isolamento & purificaçãoRESUMO
A process is under development at the University of New South Wales to produce fermentation ethanol faster and more efficiently. The process is based on the micro-organism Zymomonas mobilis, which has higher specific rates of ethanol production and higher yields when compared with the traditionally used yeasts. By using hollow fibre membranes for cell recycle, high productivity continuous processes have been studied at laboratory-scale. Pilot scale evaluations (500 litres) are now in progress through Licence Agreements between the University and industry. Genetic manipulation and recombinant DNA techniques are being used to increase the ethanol tolerance and broaden the substrate range. Most recently glucoamylase genes from Aspergillus niger have been cloned into Escherichia coli K12 as part of a programme to enable direct fermentation of starch to ethanol by Z. mobilis.
Assuntos
Bactérias/metabolismo , Etanol/metabolismo , Fermentação , Técnicas Bacteriológicas , Clonagem Molecular , Conjugação Genética , Enzimas de Restrição do DNA , Resistência Microbiana a Medicamentos , Marcadores Genéticos , Modelos Biológicos , Mutação , Plasmídeos , Fatores R , Especificidade da Espécie , Sacarose/metabolismoRESUMO
Two years' experience with DNA analysis for the antenatal diagnosis of thalassaemia and haemophilia is described. The advantages of DNA testing, including a first-trimester diagnosis and greater availability, must be considered in relation to the problems that are associated with this procedure. In particular, the risk of recombination in DNA polymorphism studies should be understood and explained fully to the patient.
Assuntos
DNA/análise , Doenças Fetais/diagnóstico , Hemofilia A/diagnóstico , Diagnóstico Pré-Natal/métodos , Talassemia/diagnóstico , Amniocentese , Biópsia , Vilosidades Coriônicas/patologia , Mapeamento Cromossômico , Feminino , Doenças Fetais/genética , Hemofilia A/genética , Heterozigoto , Homozigoto , Humanos , Polimorfismo Genético , Gravidez , Risco , Talassemia/genéticaRESUMO
Pulmonary surfactant is a lipid-protein complex that promotes alveolar stability by lowering the surface tension at the air-fluid interface in the peripheral air spaces. A group of hydrophobic surfactant-associated proteins has been shown to be essential for rapid surface film formation by surfactant phospholipids. We have purified a hydrophobic surfactant protein of approximately 5 kDa that we term SP5 from bronchopulmonary lavage fluid from a patient with alveolar proteinosis and shown that it promotes rapid surface film formation by simple mixtures of phospholipids. We have derived the full amino acid sequence of human SP5 from the nucleotide sequence of cDNAs identified with oligonucleotide probes based on the NH2-terminal sequence of SP5. SP5 isolated from surfactant is a fragment of a much larger precursor protein (21 kDa). The precursor contains an extremely hydrophobic region of 34 amino acids that comprises most of the mature SP5. This hydrophobicity explains the unusual solubility characteristics of SP5 and the fact that it is lipid-associated when isolated from lung.
Assuntos
Surfactantes Pulmonares/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , DNA/genética , DNA Recombinante , Cães , Humanos , Dados de Sequência Molecular , Peso Molecular , Precursores de Proteínas/genética , Surfactantes Pulmonares/isolamento & purificaçãoRESUMO
Prenatal diagnosis by chorionic biopsy was undertaken between the eighth and 12th weeks of pregnancy in 50 patients at risk of chromosomal or genetic abnormalities. Samples from 45 patients were karyotyped. A DNA analysis for the detection of homozygous beta-thalassaemia was undertaken in five patients. The sample from one patient at risk of haemophilia in the fetus was subjected to DNA analysis after a male fetus was confirmed on karyotyping. Abnormal karyotypes were detected in four fetuses while three had homozygous beta-thalassaemia.