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Biomedical subjects

R L Strausberg

Publications and source records attributed to R L Strausberg.

34 records · Page 2Linked to original sources
PubMed1992

Potential of a recombinant antigen as a prophylactic vaccine for day-old broiler chickens against Eimeria acervulina and Eimeria tenella infections.

A genetically engineered Eimeria tenella antigen (GX3262), produced as a fusion protein with beta-galactosidase and identified with a monoclonal antibody, induced partial but significant protection in young broiler chickens against experimental E. tenella and Eimeria acervulina infections. The antigen appears to share a T-helper cell epitope with the parasite as evidenced by (a) booster inoculation with either the recombinant antigen or with a small number of live oocysts enhanced the protective immunity in GX3262 primed chickens, and (b) ability of the antigen to induce in vitro stimulation of T-cells from chickens immunized with antigen or parasite. These observations suggest the feasibility of a single vaccination of 1 or 2-day-old broilers with GX3262 to induce an acceptable degree of protective immunity. The implications of the observations reported here are far reaching in terms of a practical coccidiosis vaccine for poultry, and show for the first time that 1-day-old broiler chickens can be efficiently vaccinated with a recombinant antigen against one or more species of Eimeria.

Amino Acid Sequence↗
PubMed1990

Protein-based medical adhesives.

There are many naturally occurring adhesive proteins which have potential for application in medicine and dentistry. Cloning and expression of their genes enables the modes of action of these proteins to be better understood and increases their availability for practical applications. This article concentrates on the adhesive protein from the blue mussel Mytilus edulis but also describes medical adhesives based on fibrin isolated from human blood.

Amino Acid Sequence↗
PubMed1989

Characterization and vaccine potential of a novel recombinant coccidial antigen.

A cDNA clone derived from sporulated oocysts of Eimeria tenella and encoding the expression product GX3262 was identified using a monoclonal antibody raised against Eimeria acervulina sporozoites. The cDNA fragment containing the coccidial antigen gene was cloned in bacteriophage lambda gt11, transferred to a plasmid, and introduced into Escherichia coli for analysis of the gene products. The strain carrying the plasmid produced GX3262 as part of a fusion protein consisting of the first 1,006 amino acids of E. coli beta-galactosidase and 112 amino acids of the E. tenella protein of approximately 12 kilodaltons. Partially purified antigen, heat-killed recombinant bacterin, and live E. coli containing the recombinant coccidial antigen were used to immunize 1-week-old or newly hatched broiler chicks. Several immunization protocols were utilized, including boosts with partially purified beta-galactosidase-GX3262, bacterin, or small numbers of live E. tenella oocysts. After challenge with an experimental E. tenella infection, the birds were evaluated by scoring cecal lesions to determine the level of protection. The greatest degree of protection was seen after only a single immunization of 2-day-old birds with a live recombinant E. coli preparation. The results presented here identify GX3262 as a potential candidate coccidial vaccine antigen and provide evidence for the first time that newly hatched chickens can be successfully vaccinated with a recombinant antigen.

Amino Acid Sequence↗
PubMed1989

Genetically engineered antigen confers partial protection against avian coccidial parasites.

A fusion protein of beta-galactosidase and Eimeria tenella produced in a recombinant Escherichia coli strain was injected into chickens and elicited partial protection against an oral challenge with Eim. tenella parasites. The fusion protein contained a 31 kilodalton (kD) coccidial antigen designated as 5401. The DNA sequencing of the 5401 antigen-coding sequence revealed that this protein segment was highly negatively charged and strongly hydrophilic, and contained an amino-acid sequence repeated five times. A dose-titration study showed that immunizing chickens with a single subcutaneous injection of the 5401 antigen at 1,200 to 4,800 nanograms (ng)/bird in Freund's complete adjuvant decreased lesion scores, mortality, and feed conversions compared to unimmunized, challenged controls. Using the 1,200 and 2,400 ng/bird of the 5401 antigen, group weight gains were higher than for the unimmunized, challenged birds. In three other trials using the 5401 antigen at 2,400 ng/bird with light, medium, and heavy coccidial infections, significant protection was evidenced by reduced lesion scores, increased individual weight gains, or both. In addition, feed conversions were reduced when compared with unimmunized controls or birds immunized with a noncoccidial protein E. coli extract. Western blot analysis of sporozoite preparations with serum from 5401-immunized birds labeled two antigenic bands of 66 and less than 200 kD. These results indicate that the coccidial proteins produced in E. coli are potentially effective immunogens for protecting chickens against avian coccidiosis.

Amino Acid Sequence↗
PubMed1981

Gene conversion at the var1 locus on yeast mitochondrial DNA.

Alleles of the var1 locus on yeast mtDNA determine the apparent size of the mitochondrial translation product, var1 polypeptide. We have analyzed most of the different var1 alleles in our collection, which number at least 15, and have developed procedures and a genetic rationale for determining their origin and predicting their behavior in crosses. The var1 alleles are characterized by two genetically defined segments, designated a and b, which can move from one var1 allele to another by asymmetric gene conversion. We show that the a segment behaves as an entity in recombination; it is either present in or absent from different var1 alleles. The b segment usually, but not always, recombines as an entity; in some cases, only portions of the b segment recombine by gene conversion. Thus, the total number of electrophoretically resolvable var1 species we observe is explained by the assortment of a, b, and partial b segments. Each segment recombines at a characteristic frequency; however, one example is presented which shows that the recipient can modulate the frequency of gene conversion. Finally, we show that, like the 21S rDNA region (omega), there is polarity of gene conversion within var1.

Alleles↗
PubMed1978

Asymmetric gene conversion at inserted segments on yeast mitochondrial DNA.

Different molecular weight forms of the protein product of the yeast mitochondrial gene var 1 are shown at arise by a process of asymmetric gene conversion. These different forms can be accounted by two DNA segments, 36 and 57 base pairs long, present in one allelic form of the var 1 structural gene, which can be inserted independently and at different frequencies into other var 1 alleles.

Alleles↗
PubMed1977

Expression of petite mitochondrial DNA in vivo: zygotic gene rescue.

A protocol is introduced for probing the organization and regulation of expression of the yeast mitochondrial genome, termed "zygotic gene rescue." The procedure is based on the notion that genes retained on mitochondrial DNA of on the notion that genes retained on mitochondrial DNA of petites can be expressed in zygotes of a cross between petite and wild type. To test the validity of this notion, we have taken advantage of our ability to discriminate, by mobility differences on sodium dodecyl sulfate/polyacrylamide gels, different forms of the product of alleles of the mitochondrial gene, varI. In petite strains that have retained the varI gene, its characteristic product appears in zygotes 4-5 hr after mating; no product is observed in petite strains deleted in the varI locus. Our studies indicate that (i) expression in the zygote of the varI gene in the petite genome is not exclusively the result of recombination with mitochondrial DNA of the wild-type tester, and (ii) the varI gene is probably reiterated in the petite mitochondrial genome. The strength of the technique of zygotic gene rescue in the analysis of the mitochondrial genome is discussed.

Alleles↗
PubMedDate not supplied

Structural and functional repetition in a marine mussel adhesive protein.

The DOPA-rich polyphenolic protein secreted by the marine mussel Mytilus edulis establishes key chemical linkages in a water-resistant adhesive. Molecular cloning of the gene for this remarkable protein reveals its primary structure as one of the most repetitive proteins identified in the animal kingdom. Expression and purification of polyphenolic proteins from recombinant yeast have provided sufficient material to demonstrate adhesivity of these polypeptides in the laboratory. Adhesive tests reveal a water-resistant bonding capacity of the protein that is dependent on in vitro modification of tyrosine residues to DOPA and the subsequent oxidation to quinone.

Amino Acid Sequence↗
PubMedDate not supplied

A new cancer genome anatomy project web resource for the community.

The National Cancer Institute's Cancer Genome Anatomy Project (CGAP) is developing publicly accessible information, technology, and material resources that provide a platform for the interface of cancer research and genomics. CGAP's efforts have focused toward (1) building and annotating catalogues of genes expressed during cancer development, (2) identifying polymorphisms in those genes, and (3) developing resources for the molecular characterization of cancer-related chromosomal aberrations. To date, CGAP has produced more than 1,000,000 expressed sequence tags, approximately 3,300,000 serial analysis of gene expression tags, and identified more than 10,000 human gene-based single-nucleotide polymorphisms. To enhance access to these datasets by the research community, a new Cancer Genome Project web site (http://cgap.nci.nih.gov/) is being introduced. The web site includes genomic data for humans and mice, including transcript sequence, gene expression patterns, single-nucleotide polymorphisms, clone resources, and cytogenetic information. Descriptions of the methods and reagents used in deriving the CGAP datasets are also provided. An extensive suite of informatics tools facilitates queries and analysis of the CGAP data by the community. One of the newest features of the CGAP web site is an electronic version of the Mitelman Database of Chromosome Aberrations in Cancer.

Chromosome Aberrations↗