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PubMed2000

Sexual development in marsupials: genetic characterization of bandicoot siblings with scrotal and testicular maldevelopment.

In marsupials testis determination requires the presence of a Y chromosome. The sex determining region on the Y gene (SRY) is necessary for testicular development in eutherians and it is assumed to play a similar role in marsupials. Relatively few studies have investigated the genetic basis of sexual development, and as yet there is no direct evidence that SRY is required for testis development in marsupials. Studies on intersexual marsupials have revealed a fundamental difference between marsupial and eutherian sex determination. The scrotum of marsupials is analogous, not homologous, to the eutherian scrotum and is under the control of X-linked genes not androgens. The current study describes two bandicoot (Isoodon macrourus) siblings. Both siblings had underdeveloped male reproductive tracts and testicular dysgenesis, one was ascrotal and the other had a diminutive scrotum. Their karyotypes were normal for this species which eliminates the Y chromosome from some somatic tissues. SRY was detected by Southern blotting. SRY, ubiquitin activating enzyme-1 on the Y (UBE1Y) and glucose 6-phosphate dehydrogenase (G6PD) gene expression were examined. UBE1Y was widely expressed in many tissues. SRY gene expression was much lower than normal in the abnormal siblings and may be responsible for their failure of testicular and epididymal development. The cause of their scrotal abnormalities is unknown. It is possible that the separate defects of scrotal and testis development in the two siblings, which had normal relatives, were due to a mutation in a gene common to both developmental pathways.

Animals↗
PubMed1988

Genetic characterization of the gene hupA encoding the HU-2 protein of Escherichia coli.

The gene hupA encoding the HU-2 (HU-alpha) protein of Escherichia coli was mapped between rpoBC at 90 min and metA at 90.5 min on the K-12 genome by plasmid integration and P1-mediated transduction studies. Genetic studies using plasmid rescue techniques and physical mapping demonstrated that the gene order is rpoBC-hupA-rrnE-metA. The rpoBC is located approximately 10 kb proximal to the hupA gene, and rrnE about 8 kb distal to it. Thus, the direction of hupA gene transcription is clockwise on the E. coli map [Bachmann B.J., Microbiol. Rev. 47 (1983) 180-230].

Bacterial Proteins↗
PubMed2004

Genetic characterization of high-level gentamicin-resistant strains of Enterococcus faecalis in Iran.

The prevalence of resistance to high levels of gentamicin among 182 isolates of Enterococcus faecalis from 2 Iranian hospitals was 42%. Gentamicin resistance was associated with conjugative plasmids (>70 kb) in most strains. Fingerprinting using EcoRI and HindIII showed genetic variation among these plasmids and gave evidence of nosocomial outbreaks and persistence of infection in different wards of the study hospitals, as well as transfer of plasmids between genetically diverse isolates. Using EcoRI, hospital-based specific plasmid fingerprints were detected for the isolates that had previously proved to be unrelated by multilocus enzyme electrophoresis, suggesting the persistence of related plasmids at each hospital, though minor changes in these related plasmids could be detected with HindIII.

Anti-Bacterial Agents↗
PubMed1982

On the role of the single-stranded DNA binding protein of bacteriophage T4 in DNA metabolism. I. Isolation and genetic characterization of new mutations in gene 32 of bacteriophage T4.

The product of gene 32 of bacteriophage T4 is a single-stranded DNA binding protein involved in T4 DNA replication, recombination and repair. Functionally differentiated regions of the gene 32 protein have been described by protein chemistry. As a preliminary step in a genetic dissection of these functional domains, we have isolated a large number of missense mutants of gene 32. Mutant isolation was facilitated by directed mutagenesis and a mutant bacterial host which is unusually restrictive for missense mutations in gene 32. We have isolated over 100 mutants and identified 22 mutational sites. A physical map of these sites has been constructed and has shown that mutations are clustered within gene 32. The possible functional significance of this clustering is considered.

Base Sequence↗
PubMed1997

Rio Mamore virus: genetic characterization of a newly recognized hantavirus of the pygmy rice rat, Oligoryzomys microtis, from Bolivia.

Human hantavirus disease occurs throughout much of South America. The rodent hosts and the specific etiologic agent(s) are largely unknown, but many reported cases occurred within the habitation ranges of oryzomine rodents (rice rats). We have identified a genetically novel hantavirus (Rio Mamore virus [RM]) of the pygmy rice rat Oligoryzomys microtis in Bolivia. The complete sequence of the small (S) genome and the partial sequence of the medium (M) genome are described. This virus is closely related to the newly identified human pathogen Andes virus from Patagonia. To facilitate improved diagnosis of hantavirus infections in South America, we have expressed the complete nucleocapsid protein of RM in Escherichia coli and affinity-purified it for use in an ELISA and Western blot assays for antibodies to RM.

Amino Acid Sequence↗
PubMed2006

Genetic characterization of influenza A viruses (H5N1) isolated from 3rd wave of Thailand AI outbreaks.

Three major outbreaks of avian influenza (AI) occurred in Thailand. During the third episode in October 2005, we have isolated H5N1 viruses from one human case and three poultry cases. The whole genomes of AI viruses from human, chickens and quail from the outbreaks were characterized. Sequence analysis of eight gene segments revealed that the 2005 H5N1 viruses isolated in October 2005 were closely related to those recovered from chicken, tiger(s) and human(s) in January and July 2004. In addition, the genetic changes of the AI isolates at the HA cleavage site have been observed.

Animals↗
PubMed1989

Nucleotide sequence and genetic characterization of staphylococcal bacteriophage L54a int and xis genes.

The nucleotide sequence of a staphylococcal bacteriophage L54a DNA fragment containing genes involved in site-specific recombination was determined. Mutations generated by in vitro mutagenesis were used to map and characterize the int and xis genes. The site-specific recombination functions are tightly clustered within a 1.75-kilobase stretch of DNA fragment with the gene order of attP-int-xis. The int and xis genes are transcribed divergently. The Int protein deduced from the nucleotide sequence has a molecular weight of 41,000. Int is a basic protein with 354 amino acids of which 72 are basic and 38 are acidic. The Xis protein consists of only 59 amino acids with a molecular weight of 7,180. Unlike the Xis proteins of the lambdoid bacteriophages which are all basic proteins, L54a Xis is an acidic protein containing 13 acidic and 8 basic amino acids. The Int protein is required in both integrative and excisive reactions, whereas Xis is only required in excisive reaction. A well-conserved 40-residue region, including three perfectly conserved residues found in 15 site-specific recombinases of the integrase family that have been characterized, was also found in the L54a Int protein.

Amino Acid Sequence↗
PubMed1988

Valyl-tRNA synthetase gene of Escherichia coli K12. Molecular genetic characterization.

We report the subcloning and characterization of the molecular elements necessary for the expression of the Escherichia coli valS gene which encodes the enzyme valyl-tRNA synthetase (EC 6.1.1.9). The valS gene was subcloned from the Clarke-Carbon plasmid pLC26-22 by genetic complementation of the valS temperature-sensitive mutant strain, AB4141. The protein-coding region of the valS structural gene was determined by in vitro DNA directed coupled transcription-translation assays. Assays of cellular extracts of cells transformed with a plasmid containing a full length copy of the valS gene enhanced in vivo valyl-tRNA synthetase-specific activity 12-fold. The DNA sequences of the 5'- and 3'-terminal regions of the valS structural gene are presented. The transcription initiation sites of the valS gene were determined, in vivo and in vitro, by S1 nuclease protection studies, primer-extension analysis and both alpha-32P labeled and gamma-32P-end-labeled in vitro transcription assays. In vivo, valS transcription initiates from tandem overlapping promoters separated by seven nucleotides. In vitro, only the upstream promoter is active. The presence of several regions of hyphenated dyad symmetry overlapping the tandem promoter region are noted. The valS translational start codon (AUG) is located 93 base pairs downstream from the major transcription initiation site. The valS transcriptional unit encodes only the valyl-tRNA synthetase gene since the 3' terminus of the amino acid-coding region of this gene is followed closely (26 base pairs) by an efficient rho-independent transcription termination site.

Amino Acyl-tRNA Synthetases↗
PubMed1994

Genetic characterization of a Rhizobium meliloti lactose utilization locus.

We identified several linked genes of a lactose regulon in Rhizobium meliloti. These were lacZ, the structural gene for beta-galactosidase; lacR, the lactose repressor gene; and two genes encoding proteins of unknown function, lacW and lacX. Insertion mutants in lacW and lacZ belonged to a single genetic complementation group, and lacW appeared to lie upstream of lacZ in an operon. Expression of lacZ, lacW and lacX was repressed by lacR, and expression of lacZ and lacW was derepressed by lactose. lacZ was not required for induction of lacW by lactose, suggesting that lactose itself, rather than a processed form of lactose, may be the actual inducer molecule. Expression of all three genes was repressed by succinate, and the lacR independence of this repression showed that inducer exclusion could not be the sole mechanism. This pattern of lac gene organization and regulation differs in several ways from that observed in enteric bacteria.

DNA Transposable Elements↗
PubMed1982

Genetic characterization of the glutamate dehydrogenase gene (gdhA) of Salmonella typhimurium.

Salmonella typhimurium mutants, either devoid or glutamate dehydrogenase activity or having a thermolabile glutamate dehydrogenase protein, were used to identify the structural gene (gdhA) for this enzyme. Transductions showed that the mutations producing these phenotypes were linked to both the pncA and nit genes, placing the gdhA locus between 23 and 30 U on the S. typhimurium chromosome. Additional transductions with several Tn10 insertions established the gene order as pncA-gdhA-nit. Since few genetic markers exist in this region of the chromosome, Hfr strains were constructed to orient the pncA-gdhA-nit cluster with outside genes. Conjugation experiments provided evidence for the gene order pyrD-pncA-gdhA-nit-trp. To further characterize gdhA, we used Mu cts d1 (Apr lac) insertions in this gene to select numerous strains containing deletions with various endpoints. Transductions of these deletions with strains containing different gdh mutations and with a mutant having a thermolabile glutamate dehydrogenase protein permitted us to construct a deletion map of the gdhA region.

Chromosome Mapping↗
PubMed2005

Clinicopathologic and molecular genetic characterization of low-grade fibromyxoid sarcoma, and cloning of a novel FUS/CREB3L1 fusion gene.

Low-grade fibromyxoid sarcoma (LGFMS) is an indolent, late-metastasizing malignant soft-tissue tumor that is often mistaken for either more benign or more malignant tumor types. Cytogenetic analyses have identified a recurrent balanced translocation t(7;16) (q32-34;p11), later shown by molecular genetic approaches to result in a FUS/CREB3L2 fusion gene. Whereas preliminary studies suggest that this gene rearrangement is specific for LGFMS, its incidence in this tumor type and the possible existence of variant fusion genes have not yet been addressed. For this purpose, a series of potential LGFMS were obtained from nine different soft-tissue tumor centres and subjected to molecular analysis as well as careful histopathologic review. Reverse transcriptase-polymerase chain reaction analysis disclosed a FUS/CREB3L2 fusion transcript in 22 of the 23 (96%) cases that remained classified as LGFMS after the histologic re-evaluation and from which RNA of sufficient quality could be extracted, whereas none of the cases that were classified as other tumor types was fusion-positive. In one of the tumors with typical LGFMS appearance, we found that FUS was fused to the CREB3L1 gene instead of CREB3L2. The proteins encoded by these genes both belong to the same basic leucine-zipper family of transcription factors, and display extensive sequence homology in their DNA-binding domains. Thus, it is expected that the novel FUS/CREB3L1 chimera will have a similar impact at the cellular level as the much more common FUS/CREB3L2 fusion protein. Taken together, the results indicate that virtually all LGFMS are characterized by a chimeric FUS/CREB3L2 gene, and that rare cases may display a variant FUS/CREB3L1 fusion.

Adolescent↗
PubMed2004

Antigenic and genetic characterization of serotype G2 human rotavirus strains from the African continent.

Serotype G2 rotavirus strains were isolated in seven countries on the African continent during 1999 and 2000. To investigate the associated DS-1 genogroup characteristics, subgroup (VP6) enzyme-linked immunosorbent assay, polyacrylamide gel electrophoresis, and P genotyping were performed on 10 G2 strains. The antigenic and genetic variation of the gene encoding the major neutralization glycoprotein (VP7) was also investigated by using G2-specific monoclonal antibodies and sequence analysis. Alterations in the characteristic DS-1 genogroup gene constellations were more likely to occur in the VP4 gene, and three genotypes were observed: P[4], P[6], and a dual P[4]-P[6] type. The failure of G2-specific monoclonal antibodies to type African G2 strains was more likely due to improper storage of the original stool, although G2 monotypes were detected. Phylogenetic analyses revealed clusters of serotype G2 strains that were more commonly associated with seasons during which G2 was predominant. No rotavirus vaccine trials have been conducted in an area where G2 strains were the predominant circulating serotype, and the continued surveillance of rotavirus epidemics in Africa will be preparation for future vaccine implementation in an area that clearly needs these preventative medicines.

Africa↗
PubMed2006

Phenotypic and genetic characterization of enteropathogenic Escherichia coli (EPEC) and entero-aggregative E. coli (EAEC) from diarrhoeal and non-diarrhoeal children in Libya.

A total of 50 Escherichia coli strains isolated in a Libyan hospital (20 from children with diarrhoea and 30 from healthy children) were investigated for their pathotypes and virulence traits. Altogether nine eae-positive (enteropathogenic E. coli, EPEC) and nine aggR-positive (entero-aggregative E. coli, EAEC) strains were identified. Significantly (P=0.001) more EPEC strains were identified from diarrhoeal patients (n=8) than from healthy controls (n=1), while six EAEC strains were identified from diarrhoeal and three from healthy children. Typical (eae(+), EAF(+), bfp(+)) EPEC strains (n=6) belonged to classical EPEC serogroups O55, O114, O127 and showed localized adherence on Hela cells. EAEC strains revealed genetic heterogeneity but uniformly adhered to HeLa cultures in an entero-aggregative adherence pattern. Antibiotic resistance frequently, characterized the strains. Sixty-eight percentage of the strains were resistant against at least one antibiotic and 30% harbored a class 1 integron independently of their clinical background. This is the first report from North Africa demonstrating the significance of EPEC and EAEC.

Adhesins, Bacterial↗
PubMed2002

Molecular and genetic characterizations of five pathogenic and two non-pathogenic monoclonal antiphospholipid antibodies.

Antiphospholipid syndrome (APS) is an autoimmune disease that is characterized by thrombosis, recurrent fetal loss and thrombocytopenia. Antiphospholipid antibodies, detected by enzyme-linked immunoabsorbent assays (aCL) and/or in vitro blood clotting assays (LAC) are strongly associated with APS. Both the molecular structures used by pathogenic antiphospholipid antibodies and the genetic mechanisms leading to their production are unknown. We describe here the variable region genes of seven IgG antiphospholipid antibodies derived from two APS patients. Of these, five are pathogenic as defined in a mouse model of thrombosis and two are not. Analyses of the expressed variable region genes show no preferential V gene usage. However, similar to anti-DNA antibodies, pathogenic antiphospholipid antibodies contain an increased number of arginine residues in the third complimentarity-determining region (CDR3) of their H chains. The increased accumulation of arginine residues in the V(H) CDR3 may act to enhance antigen binding, promote disease and point to the importance of the H chain in the pathogenic potential of certain antiphospholipid antibodies.

Adolescent↗
PubMed2006

Genetic characterization of rhesus macaques (Macaca mulatta) in Nepal.

Indian-origin rhesus macaques (Macaca mulatta) have long served as an animal model for the study of human disease and behavior. Given the current shortage of Indian-origin rhesus, many researchers have turned to rhesus macaques from China as a substitute. However, a number of studies have identified marked genetic differences between the Chinese and Indian animals. We investigated the genetic characteristics of a third rhesus population, the rhesus macaques of Nepal. Twenty-one rhesus macaques at the Swoyambhu Temple in Kathmandu, Nepal, were compared with more than 300 Indian- and Chinese-origin rhesus macaques. The sequence analyses of two mitochondrial DNA (mtDNA) loci, from the HVS I and 12 S rRNA regions, showed that the Nepali animals were more similar to Indian-origin than to Chinese-origin animals. The distribution of alleles at 24 short tandem repeat (STR) loci distributed across 17 chromosomes also showed greater similarity between the Nepali and Indian-origin animals. Finally, an analysis of seven major histocompatibility complex (MHC) alleles showed that the Nepali animals expressed Class I alleles that are common to Indian-origin animals, including Mamu-A*01. All of these analyses also revealed a low level of genetic diversity within this Nepali rhesus sample. We conclude that the rhesus macaques of Nepal more closely resemble rhesus macaques of Indian origin than those of Chinese origin. As such, the Nepali rhesus may offer an additional resource option for researchers who wish to maintain research protocols with animals that possess key genetic features characteristic of Indian-origin rhesus macaques.

Animals↗