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Biomedical subjects

H Ostrer

Publications and source records attributed to H Ostrer.

At least 55 records · Page 3Linked to original sources
PubMed1996

Linkage analysis of a kindred with inherited 46,XY partial gonadal dysgenesis.

We have reported a kindred in which 46,XY gonadal dysgenesis was inherited in an X-linked (or autosomal dominant sex-limited) manner and in which affected subjects did not have a large duplication of the short arm of the X-chromosome. In the present study we used linkage and sequence analyses to test the role of X-linked and various autosomal genes in the etiology of the familial 46,XY partial gonadal dysgenesis. For analysis of X-linkage, 28 microsatellite polymorphisms and 1 restriction fragment length polymorphism were studied. The genotypes of informative family members were determined at each locus, and data were analyzed. Despite the large number of loci tested, our studies did not establish linkage between the trait and an X-chromosomal locus. With respect to the study of autosomal genes, linkage analysis using a polymorphism within the 3'-untranslated region of the WT1 gene excluded involvement of WT-1 in the etiology of the abnormal gonadal differentiation of the family in this study. Similarly, linkage analysis using four microsatellites on the distal short arm of chromosome 9 was not consistent with linkage. Linkage analysis of a locus close to the SOX9 gene as well as analysis of the coding region of the SOX9 gene suggested that this gene was not associated with the trait in the affected subjects we studied. Our data suggest the role of an autosomal gene in the abnormal gonadal differentiation in the family in the study, but do not formally exclude the role of an X-chromosome gene.

Chromosome Mapping↗
PubMed1996

High-level inducible expression of visual pigments in transfected cells.

A method for high-level expression of a functionally active, recombinant human red cone opsin was developed by adding the coding sequence for the C-terminal epitope of bovine rhodopsin onto the C terminus of the cone opsin and cloning the resulting construct into the vector pMEP4 beta. The recombinant pMEP4 beta vector was transfected stably into 293-EBNA cells, and expression of the cone opsin was induced by the addition of CdCl2 into the medium. The recombinant cone opsin was reconstituted with 11-cis retinal and purified by immunoaffinity chromatography. Spectral analysis prior to and following photobleaching confirmed its identity as a red cone opsin. The protein was targeted to the cell membrane and activated bovine transducin.

Animals↗
PubMed1995

Inverted repeats are necessary for circularization of the mouse testis Sry transcript.

Circular non-polyadenylated RNA molecules have been identified as stable transcription products of the human ETS-1 and mouse Sry genes. RNA circularization has been proposed to require two steps. The first step utilizes intramolecular base pairing to produce a transient stem-loop structure. The second step involves splicing a downstream donor splice site (DSS) to a now closely appositioned upstream acceptor splice site (ASS) within the loop. We demonstrate that the presence of long inverted repeats (IR) flanking the mouse Sry gene leads to the formation of the Sry circular transcript in cultured cells. Circularization requires the presence of both IR. As few as 400 complementary nt are necessary for this process. The presence of the IR does not significantly stimulate intermolecular annealing and trans-splicing in vivo.

Animals↗
PubMed1995

Prenatal diagnostic testing for familial dysautonomia using linked genetic markers.

Familial dysautonomia (FD), a recessively inherited disease, has been mapped to chromosome 9q31. Highly polymorphic dinucleotide repeat markers flanking the genetic locus and at the same genetic location have been identified. We describe the prenatal diagnosis of FD using linkage and linkage disequilibrium analyses with these markers. Twelve families were analysed for informativeness and of these, seven went on to have prenatal testing (a total of eight fetuses tested). All of these fetuses were predicted to be heterozygous unaffected (FD carriers). Seven fetuses have come to term and are normal. In the absence of a recombinant proband, a panel of three proximal and three distal markers is sufficient to provide informative flanking markers and an 87-96 per cent likelihood of a highly predictive test. In an additional family at 1:4 risk for FD, no DNA was available from the propositus. This family was analysed using linkage disequilibrium to the #18 allele of the tightly linked marker D9S58 in conjunction with linkage analysis using data from two unaffected children. Prenatal diagnosis in this family indicated an affected fetus.

Base Sequence↗
PubMed1995

Functional comparison of the Mus musculus molossinus and Mus musculus domesticus Sry genes.

The Sry gene functions as a genetic switch initiating testicular development of the indifferent mammalian gonad. The Mus musculus molossinus Sry open reading frame (ORF) encodes a 395-amino acid transcription factor (mSry) that specifically binds and bends DNA through its N-terminal HMG domain and activates transcription through its long C-terminal (residues 144-366) glutamine/histidine-rich activation domain. The M. m. domesticus Sry ORF encodes a highly homologous, truncated protein (dSry) of approximately 230 amino acids, and the molecular basis for truncation is a point mutation that creates an amber stop codon within the activation domain. The mSry protein activates transcription of a Sry-responsive reporter gene in HeLa cells, but dSry does not. Gene swapping and in vitro DNA binding experiments revealed that lack of transcriptional activation by dSry was not the result of polymorphisms within the first 137 amino acids of the protein. Direct analysis of the C-terminal glutamine/histidine-rich domain revealed that dSry lacked a functional transcriptional activation domain. Fusion of the GAL4 DNA-binding domain to the C-terminal deletion mutants of the GAL4-mSry chimeric protein indicated that residues 263-345 of the glutamine/histidine-rich domain were necessary for high level transactivation. Furthermore, readthrough of the premature amber stop codon by transfer RNA suppression resulted in a strong GAL4-dSry transactivator. This demonstrated that the premature stop codon is the only polymorphism responsible for the inability of the dSry glutamine/histidine-rich region to transactivate.

Animals↗
PubMed1994

Conservation of human Y chromosome sequences among male great apes: implications for the evolution of Y chromosomes.

Nine newly described single-copy and low-copy-number genomic DNA sequences isolated from a flow-sorted human Y chromosome library were mapped to regions of the human Y chromosome and were hybridized to Southern blots of male and female great ape genomic DNAs (Gorilla gorilla, Pan troglodytes, Pongo pygmaeus). Eight of the nine sequences mapped to the euchromatic Y long arm (Yq) in humans, and the ninth mapped to the short arm or pericentromeric region. All nine of the newly identified sequences and two additional human Yq sequences hybridized to restriction fragments in male but not female genomic DNA from the great apes, indicating Y chromosome localization. Seven of these 11 human Yq sequences hybridized to similarly-sized restriction endonuclease fragments in all the great ape species analyzed. The five human sequences that mapped to the most distal subregion of Yq (deletion of which region is associated with spermatogenic failure in humans) were hybridized to Southern blots generated by pulsed-field gel electrophoresis. These sequences define a region of approximately 1 Mb on human Yq in which HpaII tiny fragment (HTF) islands appear to be absent. The conservation of these human Yq sequences on great ape Y chromosomes indicates a greater stability in this region of the Y than has been previously described for most anonymous human Y chromosomal sequences. The stability of these sequences on great ape Y chromosomes seems remarkable given that this region of the Y does not undergo meiotic recombination and the sequences do not appear to encode genes for which positive selection might occur.

Animals↗
PubMed1994

Sry is a transcriptional activator.

The SRY gene functions as a genetic switch in gonadal ridge initiating testis determination. The mouse Sry and human SRY open reading frames (ORFs) share a conserved DNA-binding domain (the HMG-box) yet exhibit no additional homology outside this region. As judged by the accumulation of lacZ-SRY hybrid proteins in the nucleus, both the human and mouse SRY ORFs contain a nuclear localization signal. The mouse Sry HMG-box domain selectively binds the sequence NACAAT in vitro when challenged with a random pool of oligonucleotides and binds AACAAT with the highest affinity. When put under the control of a heterologous promotor, the mouse Sry gene activated transcription of a reporter gene containing multiple copies of the AACAAT binding site. Activation was likewise observed for a GAL4-responsive reporter gene, when the mouse Sry gene was linked to the DNA-binding domain of GAL4. Using this system, the activation function was mapped to a glutamine/histidine-rich domain. In addition, LexA-mouse Sry fusion genes activated a LexA-responsive reporter gene in yeast. In contrast, a GAL4-human SRY fusion gene did not cause transcriptional activation. These studies suggest that both the human and the mouse SRY ORFs encode nuclear, DNA-binding proteins and that the mouse Sry ORF can function as a transcriptional activator with separable DNA-binding and activator domains.

Animals↗
PubMed1993

Ethical and practical implications of the human genome initiative for family medicine.

Major advances in predictive genetic testing resulting from the Human Genome Initiative could change significantly the routine practice of family medicine. Family physicians should be aware that increased genetic information may affect patients' abilities to acquire and maintain insurance and employment and that interested parties will have incentives to seek this information. The social consequences of genetic information, as well as increased health promotion efforts, may raise problems of informed consent and confidentiality. In addition to their ethical implications, these developments will also affect the practice of family physicians in practical ways such as record keeping. We discuss cases that illustrate the potential impact of these emerging technologies on the practice of family medicine.

Adult↗
PubMed1993

Insurance and genetic testing: where are we now?

Basic research will spur development of genetic tests that are capable of presymptomatic prediction of disease, disability, and premature death in presently asymptomatic individuals. Concerns have been expressed about potential harms related to the use of genetic test results, especially loss of confidentiality, eugenics, and discrimination. Existing laws and administrative policies may not be sufficient to assure that genetic information is used fairly. To provide factual information and conceptual principles upon which sound social policy can be based, the Human Genome Initiative established an Ethical, Legal, and Social Issues Program. Among the first areas to be identified as a priority for study was insurance. This paper provides a review of life, health, and disability insurance systems, including basic principles, risk classification, and market and regulatory issues, and examines the potential impact of genetic information on the insurance industry.

Persons with Disabilities↗
PubMed1991

Evolution and sequence analysis of a human Y-chromosomal DNA fragment.

A Y-chromosomal DNA fragment has been isolated from a human Y-Charon 21A recombinant library. Evolutionary analysis of 1F5 indicates that the size and sequence of this fragment have been conserved in higher primates. Deletion mapping and in situ hybridization analysis have localized 1F5 to the middle euchromatic portion of the long arm of the human Y chromosome at Yq11.2. Sequence analysis revealed the presence of an atypical Alu element and two regions rich in polypyrimidine-polypurine residues.

Base Sequence↗
PubMed1991

Single-copy flanking sequences in human histone gene clusters map to chromosomes 1 and 6.

Two single-copy sequences flanking two different human histone gene clusters were used as probes to map these clusters by in situ hybridization. pFF435B, a unique sequence subclone derived from a lambda genomic clone (lambda HHG55) containing H2A, H2B, H3, and H4 genes, mapped to chromosome 1q21 (chi 2 = 120.99, P less than 0.001). pST519E, a single-copy sequence derived from a lambda genomic clone (lambda HHG17) containing only H3 and H4 genes, mapped to chromosome 6p21 (chi 2 = 112.62, P less than 0.001). These findings agree with previous assignments of human histone genes to chromosomes 1 and 6 and demonstrate that the single-copy flanking sequences in different human histone gene clusters are unique for different chromosomes.

Chromosomes, Human, Pair 1↗
PubMed1991

A Y-chromosomal DNA fragment is conserved in human and chimpanzee.

A human male-specific Y-chromosomal DNA fragment (lambda YH2D6) has been isolated. By deletion-mapping analysis, 2D6 has been localized to the euchromatic portion of the long arm (Yq11) of the human Y chromosome. Among great apes, this fragment was found to be conserved in male chimpanzee but was lacking in male gorilla and male orangutan. No homologous fragments were detected in females of orangutan, gorilla, chimpanzee, or human. Nucleotide sequence analysis indicated the presence of partial-Alu-elements and of sequences similar to the GATA repeats of the snake Bkm sequence.

Animals↗
PubMed1991

Maternal serum alphafetoprotein screening. University Medical Center.

University Medical Center in Jacksonville initiated a screening program for maternal serum alphafetoprotein (MSAFP) in October 1987. Women with both high and low values were recalled for testing. During the first two years, neural tube and other birth defects including cystic hygroma and gastroschisis were detected. No chromosomal abnormalities were found. The program meets the recommendation of the American College of Obstetrics and Gynecology to offer MSAFP testing to all pregnant women. Pregnant women in other areas of Florida could receive services through similar programs.

Academic Medical Centers↗
PubMed1990

Maternal origin of 15q11-13 deletions in Angelman syndrome suggests a role for genomic imprinting.

Six persons with the classical Angelman syndrome (AS) phenotype and de novo deletions of chromosome 15q11-q13 were studied to determine the parental origin of the chromosome deletion. Four of the 6 patients had informative cytogenetic studies and all demonstrated maternal inheritance of the deletion. These findings, together with other reported cases of the origin of the chromosome 15 deletion in AS, suggest that deletion of the maternally contributed chromosome leads to the AS phenotype. This contrasts with the Prader-Willi syndrome (PWS) in which a similar deletion of the paternally contributed chromosome 15 is observed. In deletion cases, a parental gamete effect such as genomic imprinting may be the best model to explain why apparently identical 15q11-q13 deletions may develop the different phenotypes of AS or PWS.

Chromosome Deletion↗