RESUMEN
BACKGROUND: Psoriasis is a common chronic inflammatory skin disease caused by genetic and epigenetic factors. There are conflicting results in the literature about the association between psoriasis and the methylenetetrahydrofolate reductase gene (MTHFR), ranging from strong linkage to no association. AIM: To investigate the association between the germline MTHFR polymorphisms C677T and A1298C with psoriasis risk in a Turkish population. METHODS: The study enrolled 84 patients with psoriasis and 212 healthy controls (HCs) without any history of psoriasis. DNA was extracted from peripheral blood samples of patients and HCs, and real-time PCR was used for genotyping. Results were compared by Pearson χ² test and multiple logistic regression models. RESULTS: The frequency of both the MTHFR 677TT and A1298C (homozygous) genotypes was statistically significantly different from HCs. Point mutations were detected in all patients with early-onset psoriasis (before the age of 20 years). The T allele of MTHFR 677 and the C allele of MTHFR 1298 increased psoriasis risk by 12.4- and 17.0-fold, respectively, in patients compared with HCs. CONCLUSION: A possible association was detected betweengermline MTHFR 677 C>T and 1298 A>C genotypes and psoriasis risk in a Turkish population. These results need to be confirmed in further studies with larger sample sizes.
Asunto(s)
Predisposición Genética a la Enfermedad , Mutación de Línea Germinal , Metilenotetrahidrofolato Reductasa (NADPH2)/genética , Polimorfismo Genético , Psoriasis/genética , Adolescente , Adulto , Anciano , Alelos , Niño , Preescolar , Análisis Mutacional de ADN , Femenino , Frecuencia de los Genes , Genotipo , Humanos , Masculino , Metilenotetrahidrofolato Reductasa (NADPH2)/metabolismo , Persona de Mediana Edad , Prevalencia , Psoriasis/epidemiología , Psoriasis/metabolismo , Reacción en Cadena en Tiempo Real de la Polimerasa , Factores de Riesgo , Turquía/epidemiología , Adulto JovenRESUMEN
The CY2C19 and P2Y12 gene polymorphisms are responsible for resistance to clopidogrel, known as drug unresponsiveness. In this study we researched the effect of gene polymorphism on clinical results of patients who began clopidogrel therapy after acute ischemic cerebrovascular disease. The study included 51 patients. The patient group included patients who had begun prophylactic clopidogrel due to acute ischemic cerebrovascular disease in the last 2 years. All patients were monitored by the Neurology Outpatient Clinic at Çanakkale Onsekiz Mart Üniversity Research Hospital, Çanakkale, Turkey, and only those monitored for at least 1 year were included in the study. When the *1, *2 and *3 alleles of the CYP2C19 gene polymorphism were evaluated, two patients were homozygotes for *2/*2, 13 patients were heterozygous for *1/*2 and 36 patients were homozygotes for the wild type *1/*1. No patient had the *3 allele. Three heterozygous patients, one for *2/*2 and two for *1/*2, stopped clopidogrel therapy due to repeated strokes and began taking warfarin. When evaluating P2Y12 52 (G>T) and 34 (C>T) polymorphisms, all alleles were of the wild type. The CYP2C19 and P2Y12 gene polymorphisms may cause recurring strokes linked to insufficient response to treatment of ischemic cerebrovascular disease. In our patient group, three patients suffered repeated strokes and these patients had the CYP2C19*2 gene polymorphism. As a result, before medication use, genetic testing is important for human life, quality of life and economic burden.
RESUMEN
We studied the role of the resting period (1, 2, 4, 8, 16 min; n = 6-7), external Ca2+ (0.2, 0.4, 0.6 g/l; n + 5-6), stimulation frequency (1, 2, 3 Hz; n = 6), 4-aminopyridine (4-AP, 2 mM; n = 5); theophylline (1 mM; n = 6), ouabain (5 microM; n = 6), and verapamil (1 microM; n = 6) on post-rest adaptation in the isolated left atria of rats driven electrically by a 2x threshold intensity for 2 ms. Resting periods resulted in three-phasic adaptive changes in contractility during the post-rest stimulation before normalization: P1, hypercontractile phase, an initial twitch potentiation; P2, post-rest hypocontractile decay reached after 8 to 12 single twitches; and P3, a late reactive hypercontractile phase marked less than that of P1 and gradually declining to the pre-resting level. P1 and P2 were augmented along with increasing the resting period from 1 min to 16 min, whereas t1 (time between P1 and P2) shortened and P2 and t2 (time between P2 and P3) were not affected. P1 and P3 to become more apparent after shifting the stimulation frequency from 1 Hz to 3 Hz, accompanied by a shortening of t1 and t2 (p < 0.05) and an insignificant reversal of P2. An increase in Ca2+ concentration by 2- or 3-fold at 2 Hz reduced P1 was and antagonized P2, while leaving other parameters almost unaffected. The reduction of P1 by Ca2+ became more prominent at 3 Hz. Exposure to 4-AP depressed P1 and P3 at 1 Hz, which was reversed by increasing the stimulation frequency--P3 tended to diminish, whereas t1 and t2 were shortened. Theophylline reduced P1 antagonized P2, and shortened t1 and t2 significantly, and a combination of theophylline and 4-AP augmented the effects. Ouabain increased P1 and P2 in a frequency-dependent manner; prolonged t2 at 1 Hz, but shortened t2 at higher frequencies. Verapamil inhibition of Ca2+ channels augmented P1 and t1 and reduced P2 and P3, and the effects on all three parameters were augmented by combined 4-AP/verapamil. We concluded that the post-rest adaptive changes in contractility are a consequence of phasic changes in sarcoplasmic Ca2+ concentration and that such changes reflect an imbalance between the release from and uptake into the sarcoplasmic reticulum of Ca2+ and transsarcolemmal Ca2+ loss.
Asunto(s)
Adaptación Fisiológica/fisiología , Corazón/fisiología , Descanso/fisiología , 4-Aminopiridina/farmacología , Adaptación Fisiológica/efectos de los fármacos , Animales , Calcio/farmacología , Bloqueadores de los Canales de Calcio/farmacología , Cardiotónicos/farmacología , Estimulación Eléctrica , Femenino , Corazón/efectos de los fármacos , Atrios Cardíacos/efectos de los fármacos , Técnicas In Vitro , Masculino , Contracción Miocárdica/efectos de los fármacos , Ouabaína/farmacología , Bloqueadores de los Canales de Potasio/farmacología , Ratas , Ratas Sprague-Dawley , Teofilina/farmacología , Vasodilatadores/farmacología , Verapamilo/farmacologíaRESUMEN
We studied the renovascular action of adenosine on isolated perfused rat 10 min after drug injections. Adenosine was applied intraarterially as a single bolus injection in logarithmically increasing doses (0.3-30 microg). Adenosine treatment induced a biphasic vascular-response, namely, an initial vasoconstriction followed by a long-lasting vasodilation. Pretreatment with 0.1. 0.3, or 1.0 mM theophylline or quinidine (2 microg/ml) significantly depressed both components of the adenosine response. The vasoconstrictor response to adenosine was not affected by either 0.5 or 1.0 microg/ml dihydroergocristine. whereas the vasodilatory response was dose-dependently reduced. The biphasic response to adenosine was markedly depressed by 10 microg/ml indomethacin and was augmented by combining this agent with quinidine. We studied the possible roles of the platelet activating factor (PAF) and nitric oxide-cGMP systems in the renovascular actions of adenosine. Tebokan (a PAF antagonist) antagonized both components of the response, but methylene blue (MM) reduced only the pressory part Electron-microscopic examination of kidneys exposed for 15 min to MM showed some acute degenerative alterations and constriction in the glomeruli. From these findings, we conclude that the P1/A1, and P2x purinoceptors, the prostaglandins, PAF, and the NO-cGMP systems have a share in the renovascular actions of adenosine.
Asunto(s)
Adenosina/farmacología , Circulación Renal/efectos de los fármacos , Vasodilatadores/farmacología , Animales , Presión Sanguínea/efectos de los fármacos , Femenino , Guanosina Monofosfato/fisiología , Técnicas In Vitro , Riñón/efectos de los fármacos , Riñón/ultraestructura , Masculino , Óxido Nítrico/fisiología , Factor de Activación Plaquetaria/farmacología , Prostaglandinas/fisiología , Ratas , Ratas Sprague-Dawley , Receptores Purinérgicos/efectos de los fármacos , Sistema Nervioso Simpático/efectos de los fármacosRESUMEN
4-Aminopyridine (4-AP), a K(+)-channel blocker, has been associated with cellular Ca2+ movements in various excitable tissues but its interaction with intracellular Ca2+ pools has not been described. Spontaneously beating ventricular strips of frog hearts responded to 4-AP (1.6 x 10(-2) M) by contracture that was susceptible to tolerance development when 4-AP was applied in a repetitive manner after washout periods. Under full mechanical inhibition by Ca(2+)-free Ringer or high-K+ Ringer or a combination of both, 4-AP could still produce contracture, a finding indicating that the source of Ca2+ for such an effect should be intracellular Ca2+ pools, namely the sarcoplasmic reticulum. It was concluded that 4-AP could induce release of Ca2+ from internal stores that might be of importance in its cardiac actions.
Asunto(s)
4-Aminopiridina/farmacología , Calcio/metabolismo , Corazón/efectos de los fármacos , Miocardio/metabolismo , Retículo Sarcoplasmático/metabolismo , Animales , Estado de Descerebración/fisiopatología , Técnicas In Vitro , Contracción Miocárdica/efectos de los fármacos , Miocardio/ultraestructura , Bloqueadores de los Canales de Potasio , Rana ridibunda , Retículo Sarcoplasmático/efectos de los fármacosRESUMEN
Exposure of guinea-pig papillary muscle to 22 mM K+ resulted in loss of electromechanical excitability accompanied by an elevation of mean electrical threshold by 8.96 V and a membrane depolarization of about 47.3 mV. After setting the threshold to a new sensitive level for stimulation, 4-AP (1.25-5 x 10(-3) M) could restore both the propagated action potentials typical for Ca2+ (e.g. resting potential: -46 mV; action potential amplitude: 74.25 mV; upstroke velocity: 11.4 V/sec; abolition by Ca(2+)-channel blokers) and contractions to papillary muscle cells, with further elevation of resting potential from -51.2 mV to -46 mV. Restoration of electromechanical activity by 4-AP was dose-dependent and susceptible to blockade with D600 (5 x 10(-7) M). From these data, it was concluded that 4-AP restored electrical and mechanical excitability by increasing membrane conductance to Ca2+ (gCa2+).
Asunto(s)
4-Aminopiridina/farmacología , Potenciales de Acción/efectos de los fármacos , Calcio/farmacología , Músculos Papilares/efectos de los fármacos , Bloqueadores de los Canales de Potasio , Animales , Bloqueadores de los Canales de Calcio/farmacología , Estimulación Eléctrica , Galopamilo/farmacología , Cobayas , Técnicas In Vitro , Contracción Miocárdica/efectos de los fármacos , Potasio/farmacologíaRESUMEN
The effect of adenosine on pulmonary vessels was studied in isolated perfused rat lungs. Drugs were administered intra-arterially in a fixed volume of 0.1 ml Krebs solution as bolus injections. Adenosine responses were obtained before and 10 min after drug injections. When applied in logarithmically increasing doses (1-100 micrograms/ml), adenosine caused dose-dependent increases in pulmonary perfusion pressure (e.g. pulmonary vasoconstriction) which were readily reversible. Challenging adenosine with quinidine, dihydroergocristine and cyproheptadine (2 micrograms/ml each) did not significantly alter adenosine responses. Pretreatment of lungs with 0.5 mM theophylline, 10 micrograms/ml indomethacin, 30 micrograms/ml tebokan (a PAF antagonist) or 1 microgram/ml methylene blue for 10 min, however, antagonized the vasoconstrictor effect of the drug significantly. From these experiments, it was concluded that the mechanisms underlying the pulmonary vasoconstrictor action of adenosine are complex, and that both types of purinoceptors, prostaglandins, PAF and other vascular endothelial hormones might be involved.
Asunto(s)
Adenosina/farmacología , Extractos Vegetales , Arteria Pulmonar/efectos de los fármacos , Antagonistas de Receptores Purinérgicos P1 , Vasoconstricción/efectos de los fármacos , Adenosina/antagonistas & inhibidores , Antagonistas Adrenérgicos , Animales , Inhibidores de la Ciclooxigenasa/farmacología , Ciproheptadina/farmacología , Dihidroergotoxina/farmacología , Endotelio Vascular/efectos de los fármacos , Endotelio Vascular/fisiología , Femenino , Flavonoides/farmacología , Ginkgo biloba , Técnicas In Vitro , Indometacina/farmacología , Masculino , Azul de Metileno/farmacología , Factor de Activación Plaquetaria/antagonistas & inhibidores , Arteria Pulmonar/fisiología , Antagonistas del Receptor Purinérgico P2 , Quinidina/farmacología , Ratas , Ratas Sprague-Dawley , Teofilina/farmacología , Vasoconstricción/fisiologíaRESUMEN
BACKGROUND: Evaluation of gene expression in failing human heart has been limited by the availability of cardiac tissue. METHODS AND RESULTS: We used the polymerase chain reaction (PCR) to assess gene expression in small quantities of failing and nonfailing human heart. PCR is a powerful new molecular biological tool that allows a small quantity of DNA to be amplified as much as 1 million-fold. Total RNA was extracted from 3-5 mg samples of human heart and reverse-transcribed to complementary DNA (cDNA). With selected oligonucleotide primers, we used PCR to amplify cDNAs encoding atrial natriuretic peptide, beta-myosin heavy chain, phospholamban, and cytoskeletal beta-actin. To quantify the relative levels of messenger RNA (mRNA) in human heart, a known amount of a control RNA was present in the reverse transcription and PCR reactions. The amount of mRNA in the sample could therefore be assessed in relation to the amount of control product. The control RNA was transcribed from a synthetic DNA template containing primers complementary to those used to amplify the cDNAs of interest. Atrial natriuretic factor mRNA could not be detected in nonfailing human heart but was abundant in ventricular myocardium from failing human heart. In contrast, steady-state levels of phospholamban mRNA decreased, whereas levels of beta-myosin heavy-chain mRNA were unchanged with heart failure. CONCLUSIONS: Alterations in gene expression in the failing human heart appear to be selective. In addition, the present study suggests that PCR provides a rapid and economical way to quantify the expression of multiple genes of interest in endomyocardial biopsy specimens and may therefore be used to advance our understanding of heart muscle disease.
Asunto(s)
Gasto Cardíaco Bajo/genética , Endocardio/metabolismo , Regulación de la Expresión Génica , Miocardio/metabolismo , ARN Mensajero/metabolismo , Biopsia , Gasto Cardíaco Bajo/metabolismo , Cardiomiopatía Dilatada/metabolismo , Cardiomiopatía Dilatada/patología , ADN/metabolismo , Endocardio/patología , Humanos , Miocardio/patología , Concentración Osmolar , Reacción en Cadena de la Polimerasa , EspectrofotometríaRESUMEN
The gene for the type I interleukin-1 (IL-1) receptor has been mapped in both mouse and human. In the human genome, a combination of segregation analysis of rodent-human hybrid cells and chromosomal in situ hybridization has placed the gene on the long arm of chromosome 2, at band 2q12. This is near the reported map position of the loci for IL-1 alpha and IL-1 beta (2q13----2q21). The murine gene has been mapped by analysis of restriction fragment length polymorphisms in interspecific backcrosses to the centromeric end of chromosome 1, in a region that is syntenic to a portion of human chromosome 2. The murine Il-1r1 gene has thus been separated from the IL-1 genes, which lie on murine chromosome 2.
Asunto(s)
Cromosomas Humanos Par 2 , Interleucina-1/metabolismo , Receptores Inmunológicos/genética , Animales , Mapeo Cromosómico , Cruzamientos Genéticos , Genes , Ligamiento Genético , Humanos , Células Híbridas , Ratones , Hibridación de Ácido Nucleico , Polimorfismo de Longitud del Fragmento de Restricción , Receptores Inmunológicos/metabolismo , Receptores de Interleucina-1 , Recombinación GenéticaRESUMEN
Interspecific mouse backcross analysis was used to generate a molecular genetic linkage map of mouse chromosome 10. The map locations of the Act-2, Ahi-1, Bcr, Braf, Cdc-2a, Col6a-1, Col6a-2, Cos-1, Esr, Fyn, Gli, Ifg, Igf-1, Myb, Pah, pgcha, Ros-1 and S100b loci were determined. These loci extend over 80% of the genetic length of the chromosome, providing molecular access to many regions of chromosome 10 for the first time. The locations of the genes mapped in this study extend the known regions of synteny between mouse chromosome 10 and human chromosomes 6, 10, 12 and 21, and reveal a novel homology segment between mouse chromosome 10 and human chromosome 22. Several loci may lie close to, or correspond to, known mutations. Preferential transmission of Mus spretus-derived alleles was observed for loci mapping to the central region of mouse chromosome 10.
Asunto(s)
Mapeo Cromosómico , Cruzamientos Genéticos , Ligamiento Genético , Marcadores Genéticos , Animales , Southern Blotting , Cromosomas Humanos , Sondas de ADN , Femenino , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Polimorfismo de Longitud del Fragmento de Restricción , Homología de Secuencia de Ácido NucleicoRESUMEN
We have generated a 30-cM molecular genetic linkage map of the proximal half of mouse chromosome 14 by interspecific backcross analysis. Loci that were mapped in this study include Bmp-1, Ctla-1, Hap, hr, Plau, Psp-2, Rib-1, and Tcra. A region of homology between mouse chromosome 14 and human chromosome 10 was identified by the localization of Plau to chromosome 14. This interspecific backcross map will be valuable for establishing linkage relationships of additional loci to mouse chromosome 14.
Asunto(s)
Muridae/genética , Animales , Mapeo Cromosómico , Cromosomas Humanos Par 10 , Cruzamientos Genéticos , Ligamiento Genético , Marcadores Genéticos , Humanos , Ratones , Ratones Endogámicos C57BL/genética , Polimorfismo de Longitud del Fragmento de Restricción , Homología de Secuencia de Ácido Nucleico , Especificidad de la EspecieRESUMEN
Interspecific backcross mice were used to create a molecular genetic linkage map of chromosome 2. Genomic DNAs from N2 progeny were subjected to Southern blot analysis using molecular probes that identified the Abl, Acra, Ass, C5, Cas-1, Fshb, Gcg, Hox-5.1, Jgf-1, Kras-3, Ltk, Pax-1, Prn-p, and Spna-2 loci; these loci were added to the 11 loci previously mapped to the distal region of chromosome 2 in the same interspecific backcross to generate a composite multilocus linkage map. Several loci mapped near, and may be the same as, known mutations. Comparisons between the mouse and the human genomes indicate that mouse chromosome 2 contains regions homologous to at least six human chromosomes. Mouse models for human diseases are discussed.
Asunto(s)
Mapeo Cromosómico , Muridae/genética , Animales , Cruzamientos Genéticos , Modelos Animales de Enfermedad , Ligamiento Genético , Humanos , Ratones , Ratones Endogámicos C57BL/genética , Ratones Mutantes/genética , Oncogenes , Polimorfismo de Longitud del Fragmento de Restricción , Homología de Secuencia de Ácido Nucleico , Especificidad de la EspecieRESUMEN
Chromosomal locations have been assigned to seven members of the TGF-beta superfamily using an interspecific mouse backcross. Probes for the Tgfb-1, -2, and -3, Bmp-2a and -3, and Vgr-1 genes recognized only single loci, whereas the Bmp-2b probe recognized two independently segregating loci (designated Bmp-2b1 and Bmp-2b2). The results show that the seven members of the TGF-beta superfamily map to eight different chromosomes, indicating that the TGF-beta family has become widely dispersed during evolution. Five of the eight loci (Tgfb-1, Bmp-2a, Bmp-2b1, Bmp-2b2, Vgr-1) mapped near mutant loci associated with connective tissue and skeletal disorders, raising the possibility that at least some of these mutations result from defects in TGF-beta-related genes.
Asunto(s)
Ratones Mutantes/genética , Familia de Multigenes , Muridae/genética , Factores de Crecimiento Transformadores/genética , Secuencia de Aminoácidos , Animales , Mapeo Cromosómico , Cruzamientos Genéticos , Genes , Ligamiento Genético , Humanos , Ratones , Ratones Endogámicos/genética , Datos de Secuencia Molecular , Polimorfismo de Longitud del Fragmento de Restricción , Homología de Secuencia de Ácido Nucleico , Especificidad de la EspecieRESUMEN
A molecular genetic linkage map of mouse chromosome 13 was constructed using cloned DNA markers and interspecific backcross mice from two independent crosses. The map locations of Ctla-3, Dhfr, Fim-1, 4/12, Hexb, Hilda, Inhba, Lamb-1.13, Ral, Rrm2-ps3, and Tcrg were determined with respect to the beige (bg) and satin (sa) loci. The map locations of these genes confirm and extend regions of homology between mouse chromosome 13 and human chromosomes 5 and 7, and identify a region of homology between mouse chromosome 13 and human chromosome 6. The molecular genetic linkage map of chromosome 13 provides a framework for establishing linkage relationships between cloned DNA markers and known mouse mutations and for identifying homologous genes in mice and humans that may be involved in disease processes.
Asunto(s)
Mapeo Cromosómico , Ligamiento Genético , Animales , Cromosomas/ultraestructura , Clonación Molecular , Cruzamientos Genéticos , Genes , Ratones , Ratones Endogámicos C57BL , FenotipoRESUMEN
The zona pellucida is a unique, oocyte-specific matrix that coats the surface of all mammalian eggs. Composed of three sulfated glycoproteins in the mouse (ZP1, ZP2, and ZP3), the zona pellucida facilitates early events in fertilization and protects the embryo during preimplantation development. Using DNA isolated from hamster-mouse somatic cell hybrids and from C57BL/6J X Mus spretus interspecific backcross progeny, Zp-2 was located on chromosome 7, 11.3 +/- 3.2 cM distal to Tyr, and Zp-3 was located on chromosome 5, 9.2 +/- 2.9 cM distal to Gus.
Asunto(s)
Mapeo Cromosómico , Proteínas del Huevo , Glicoproteínas/genética , Glicoproteínas de Membrana , Ratones/genética , Receptores de Superficie Celular , Animales , Sondas de ADN , Polimorfismo de Longitud del Fragmento de Restricción , Glicoproteínas de la Zona PelúcidaRESUMEN
The promoter region of the developmentally regulated Actin 6 gene of Dictyostelium has been dissected by a series of deletions. Functional analysis of the deletions in Dictyostelium transformants revealed two short regulatory sequences: a positive upstream element (PUE) between -599 and -572 which increases transcription by a factor of 10 but does not affect the developmental pattern of expression and an upstream activator sequence (UAS) between -249 and -215 which is essential for transcription and proper developmental regulation. The UAS partially coincides with a conserved sequence with dyad symmetry found upstream of several Dictyostelium actin genes (Romans and Firtel, 1985a).
Asunto(s)
Actinas/genética , Genes Fúngicos , Genes Reguladores , Genes , Regiones Promotoras Genéticas , Secuencia de Bases , Transcripción GenéticaRESUMEN
We cloned a 12.3-kilobase (kb) endogenous plasmid, Ddp1, found in several wild-type and laboratory strains of Dictyostelium discoideum into pBR322. The cloned plasmids have been used to cotransform D. discoideum cells with B10S, a transformation vector carrying a gene fusion conferring resistance to G418. Whereas B10S DNA alone appears to integrate in a tandem array, the cloned Ddp1 plasmids replicate extrachromosomally and are stably maintained in the absence of selection with an average copy number of 50 to 100 copies per cell. The Ddp1-derived plasmids can be directly recovered by transforming Escherichia coli with bulk nuclear DNA from these cells. Preliminary deletion analysis indicates that not all regions of Ddp1 are necessary for stable replication in D. discoideum. Several recombinant vectors which replicate extrachromosomally in D. discoideum were also isolated. One contains the Act6-neor gene fusion from B10S recombined into one of the cloned derivatives of Ddp1 and can be used to directly transform D. discoideum amoebae, selecting for G418 resistance. Another recombinant is only 5.6 kb and resulted from a deletion of a 16.6-kb cloned Ddp1 hybrid plasmid. An analysis of the vector DNAs present in clones derived from single D. discoideum transformants is also described.
Asunto(s)
Replicación del ADN , Dictyostelium/genética , Vectores Genéticos , Clonación Molecular , Enzimas de Restricción del ADN , ADN Recombinante/análisis , Hibridación de Ácido Nucleico , Plásmidos , Transformación GenéticaRESUMEN
We have constructed a new vector for transformation that carries a fusion of the Dictyostelium discoideum actin 6 promoter gene and 5' flanking region with the bacterial Tn5 NeoR (KanR) gene which can confer resistance to the aminoglycoside G418. This vector can be used to transform D. discoideum cells. Approximately 200 to 2,000 transformants were obtained per 10(7) cells. Transformed cell populations carried vector DNA at an average copy number of ca. 5 per cell, and the DNA was stable for more than 40 generations in the absence of selection. We have shown that transformed cells synthesize functional kanamycin phosphotransferase and that initiation of transcription of the actin 6-NeoR gene fusion occurs at the actin 6 cap site. Moreover, analysis of RNA isolated from transformed and untransformed cells during vegetative growth and during development indicated that the actin 6-NeoR gene fusion was regulated in parallel with the endogenous actin 6 gene, suggesting that the upstream flanking regions of actin 6 contain the cis-acting regulatory sequences sufficient for differential regulation of this gene during D. discoideum development. These results indicate that this system can be used to examine control of gene expression during D. discoideum development.