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Results for “insertion, inversion”

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PubMed1989

Behavior and cytogenetics of fruitless in Drosophila melanogaster: different courtship defects caused by separate, closely linked lesions.

The fruitless (fru) courtship mutant was dissected into three defects of male reproductive behavior, which were separable as to their genetic etiologies by application of existing and newly induced chromosomal aberrations. fru itself is a small inversion [In(3R) 90C; 91B] on genetic and cytological criteria. Uncovering the fru distal breakpoint with deletions usually led to males with two of the fru courtship abnormalities: no copulation attempts with females (hence, behavioral sterility) and vigorous courtship among males, including the formation of "courtship chains." However, certain genetic changes involving region 91B resulted in males who formed courtship chains but who mated with females. Uncovering the fru proximal breakpoint led to males that passively elicit inappropriately high levels of courtship. This elicitation property was separable genetically from the sterility and chain formation phenotypes and provisionally mapped to the interval 89F-90F, which includes the fru proximal breakpoint. Behavioral sterility and chaining were also observed in males expressing certain abnormal genotypes, independent of the fru inversion. These included combinations of deficiencies, each with a breakpoint in 91B, and a transposon inserted in 91B.

Animals↗

PubMedDate not supplied

A familial complex chromosome translocation resulting in duplication of 6p25.

We report on a girl with psychomotor retardation, severe speech developmental delay and mild dysmorphic features. Molecular cytogenetic analysis showed that the patient was carrier of an insertion (6)(p22.5-->22.4) in chromosome 12. Analysis of the chromosomes of the mother revealed the presence of a complex chromosomal rearrangement. In addition to the insertion (6)(p22.5-->22.4) in chromosome 12 and a pericentric inversion in chromosome 12, the 6p subtelomeric region was absent in the mother. This is, to our knowledge, the smallest pure duplication of chromosome 6p as well as the smallest cryptic subtelomeric 6pter deletion thus far reported.

Cells, Cultured↗

PubMed1985

Paracentric inversions in man.

Two new cases of familial paracentric inversions, 46,XY,inv(3)(p21.1p25) and 46,XY,inv(7) (q22.3q36.1) are presented. A review of published cases suggests that prenatal diagnosis for carriers of paracentric inversions is not warranted. However, care must be exercised in eliminating the possibility of insertions.

Abnormalities, Multiple↗

PubMed1985

Isomerization of herpes simplex virus 1 genome: identification of the cis-acting and recombination sites within the domain of the a sequence.

Previous studies have shown that the a sequence located at the termini and at the junction between the L and S components is the site-specific, cis-acting sequence mediating the inversions of herpes simplex virus 1 DNA. We constructed mutated a sequences, inserted them into the thymidine kinase gene, and recombined them into the L component of the viral genome. Deletion of Uc or Ub domains of the a sequence did not affect inversions, whereas the deletion of direct repeat #4 (DR4) drastically reduced their frequency. Deletion of both direct repeat #2 (DR2) and DR4 abolished inversions. Recombinational events leading to inversions appear to occur through DR2, and possibly DR4. These results complement previous studies showing that most of one DR1 sequence can also be dispensed with and are consistent with the hypothesis that DR4 and possibly DR2 are the cis-acting sites for the inversions mediated by the a sequence.

Base Sequence↗

PubMed1982

A site-specific, conservative recombination system carried by bacteriophage P1. Mapping the recombinase gene cin and the cross-over sites cix for the inversion of the C segment.

The bacteriophage P1 genome carries an invertible C segment consisting of 3-kb unique sequences flanked by 0.6-kb inverted repeats. With insertion and deletion mutants of P1 derivatives the site-specific recombinase gene cin for C inversion) has been mapped adjacent to the C segment and the cix sites (for C inversion cross-over) have been located at the outside ends of the inverted repeats. Inversion of the C segment functions as a biological switch and controls expression of the gene(s) responsible for phage infectivity carried on the C segment. The cin gene product can promote recombination between a 'quasi- cix ' site on plasmid pBR322 and a cix site on P1 DNA. The junctions formed on the resulting co-integrate can also serve as cix sites. This observation implies a potential evolutionary process to bring genes under the control of a biological switch acting by DNA inversion.

Base Sequence↗

PubMed1999

Genomic studies of the Lucké tumor herpesvirus (RaHV-1).

Ranid herpesvirus 1 (RaHV-1) is the etiological agent of the Lucké renal adenocarcinoma of the North American leopard frog Rana pipiens. Construction of cosmid libraries containing RaHV-1 DNA inserts allowed the derivation of a BamHI map for the viral genome. Summation of fragment sizes indicates that the genome is 217 kbp in size, a value in accordance with the most recent published estimate (220 kbp) obtained by field-inversion gel electrophoresis. The DNA sequence of the 39,757-bp insert in 1 cosmid (cos54) was determined and was predicted to contain 21 complete and 3 partial genes. In all, 12 genes have distant counterparts in a fish herpesvirus (ictalurid herpesvirus 1) and are present in 2 blocks, 1 of which is relatively inverted. This indicates that RaHV-1 belongs to the fish virus lineage of the herpesvirus family rather than to the lineage populated by mammalian and avian viruses. The remaining 12 genes in cos54 lack counterparts in any other herpesvirus. One of these encodes a putative DNA (cytosine-5) methyltransferase. This raises the possibility that biological processes induced in the host by RaHV-1 might involve methylation of cellular DNA by the viral enzyme.

Adenocarcinoma↗

PubMed1999

Origin of mutation in sporadic cases of haemophilia A.

The aim of this study was to define the origin of mutation in sporadic cases of severe haemophilia A. The series was composed of 31 families with sporadic severe haemophilia A in the geographical catchment area of the Malmö haemophilia centre. The mutation was characterized in 29/31 families: inversion type 1 (n = 11), inversion type 2 (n = 3), other inversion (n = 1), small or partial deletion (n = 6), insertion (n = 2), non-sense mutation (n = 4) and mis-sense mutation (n = 2). Of 29 probands, eight carried a de novo mutation, whereas the proband's mother was found to carry the mutation in 21/29 families. Of the 21 carrier mothers, 16 had de novo mutations (i.e. the proband's maternal grandfather and grandmother were non-carriers). Owing to the lack of samples from the grandparents, origin could not be determined in the remaining five families. Polymorphisms of the FVIII gene were used to determine whether the de novo mutation of the carrier mother was of paternal or maternal origin. In 15/16 cases the mutation was of paternal origin and in 1/16 cases of maternal origin. In the series as a whole, mutation frequency was 6-fold higher in males than in females, but no differences in the ratio of sex-specific mutations rates was found among different types of mutation.

Chromosome Inversion↗

PubMed1998

Sequence analysis of Tn10 insertion sites in a collection of Escherichia coli strains used for genetic mapping and strain construction.

The chromosomal insertion sites of Tn10-containing Escherichia coli strains were amplified by inverse PCR, and the nucleotide sequences of the junctions were determined. In 95 strains analyzed, 88 unique Tn10 positions were determined and matched to the E. coli chromosome sequence. Two gaps in insertion site positions were noted, one including the terminus of DNA replication and another bounded by recombination hot spots RhsA and RhsB.

Base Sequence↗

PubMed1995

Rearrangements in the genome of the bacterium Salmonella typhi.

We have determined the genomic map of the bacterium Salmonella typhi Ty2, the causal organism of typhoid fever, by using pulsed-field gel electrophoresis. Digestion of the Ty2 genome with endonucleases Xba I, Bln I, and Ceu I yielded 33, 26, and 7 fragments, respectively, that were placed in order on a circular chromosome of 4780 kb. Transposon Tn10 was inserted in specific genes of Salmonella typhimurium and transduced into S. typhi, and thus, the positions of 37 S. typhi genes were located through the Xba I and Bln I sites of the Tn10. Gene order on chromosomes of Escherichia coli K-12 and S. typhimurium LT2 is remarkably conserved; however, the gene order in S. typhi Ty2 is different, suggesting it has undergone major genomic rearrangements during its evolution. These rearrangements include inversions and transpositions in the 7 DNA fragments between the seven rrn operons for rRNA (postulated to be due to homologous recombination in these rrn genes), another inversion that covers the replication terminus region (resembling inversions found in other enteric bacteria), and at least three insertions, one as large as 118 kb. Partial digestion of genomic DNA with the intron-encoded endonuclease I-Ceu I, which cuts only in rrn genes, shows chromosomal rearrangements, apparently due to homologous recombination in the rrn genes, that were detected in all wild-type strains of S. typhi tested. These rearrangements may have been selected to compensate for the insertions that otherwise would have altered the locations of genes with respect to the origin and terminus of replication. These observations are relevant to our view of the evolution of the bacterial genome and may be significant in the virulence of S. typhi.

Chromosomes, Bacterial↗

PubMed1988

[Genetic counseling in balanced chromosomal inversions].

The genetic counseling given at carriers of equilibrated chromosomal inversions is in relation with the type of the inversion. The risk for carriers of pericentric inversions concerning euchromatic regions depends on many factors, i.e. the length of the inserted segment in relation with the total length of the chromosome involved, the sex of the carrier and the way of assortment. In contrast, the carriers of pericentric inversions concerning the heterochromatic regions, as well as of paracentric inversions, have not a particular risk for their descendance.

Aneuploidy↗

PubMed2001

Use of comparative physical and sequence mapping to annotate mouse chromosome 16 and human chromosome 21.

Distal mouse chromosome 16 (MMU16) shares conserved linkage with human chromosome 21 (HSA21), trisomy for which causes Down syndrome (DS). A 4.5-Mb physical map extending from Cbr1 to Tmprss2 on MMU16 provides a minimal tiling path of P1 artificial chromosomes (PACs) for comparative mapping and genomic sequencing. Thirty-four expressed sequences were positioned on the mouse map, including 19 that were not physically mapped previously. This region of the mouse:human comparative map shows a high degree of evolutionary conservation of gene order and content, which differs only by insertion of one gene (in mouse) and a small inversion involving two adjacent genes. "Low-pass" (2.2x) mouse sequence from a portion of the contig was ordered and oriented along 510 kb of finished HSA21 sequence. In combination with 68 kb of unique PAC end sequence, the comparison provided confirmation of genes predicted by comparative mapping, indicated gene predictions that are likely to be incorrect, and identified three candidate genes in mouse and human that were not observed in the initial HSA21 sequence annotation. This comparative map and sequence derived from it are powerful tools for identifying genes and regulatory regions, information that will in turn provide insights into the genetic mechanisms by which trisomy 21 results in DS.

Animals↗

PubMed1994

An enhancer in the first intron of the human purine nucleoside phosphorylase-encoding gene.

In previous studies characterizing intron-dependent expression of the human purine nucleoside phosphorylase-encoding gene (PNP), we identified a putative enhancer sequence in the first intron which was capable of mediating increased cat reporter gene expression in transfected murine NIH 3T3 cells in a position- and orientation-independent manner. In order to further characterize this enhancer activity, the nucleotide sequence was determined for the region of intron 1 to which this activity was originally ascribed. The sequence was analyzed for the presence of binding sites for known transcription factors, but none were identified. A 444-bp downstream portion of the intron-1 sequence enhanced cat expression either in conjunction with a human PNP promoter sequence or with a 105-bp heterologous herpes simplex virus thymidine kinase (TK) promoter. Nested deletions of the downstream intron-1 sequence fused to a TK::cat fusion gene localized the enhancer activity to a 170-bp sequence in intron 1. A 154-bp HgiAI fragment (bp 424 to 577 of intron 1) excised from this region contained enhancer activity which varied directly with the number of fragments inserted upstream from the TK::cat fusion gene. However, inversion of the HgiAI fragment in a PNP abbreviated gene, or relocation of the HgiAI fragment from intron 1 to a position upstream from the PNP promoter, reduced or eliminated PNP expression. The effect of the intron-1 enhancer element on PNP expression is thus maximized in a position- and orientation-dependent manner.

3T3 Cells↗

PubMed2005

A probable link between the DedA protein and resistance to selenite.

To understand the molecular events involved in the reduction of selenite to non-toxic elemental selenium, 4000 clones of Ralstonia metallidurans CH34 were produced by random Tn5 transposon integration mutagenesis. Eight mutants were able to resist up to 15 mM selenite while the MIC for the wild-type strain was estimated as 4-6 mM selenite. The identification of the disrupted genes was carried out by Southern blot analysis and inverse PCR. The three resistant mutants containing only one insertion were further characterized. Tn5 disrupted a gene that encoded a protein which was closely related to proteins of the DedA family. This family represents a group of integral membrane proteins with completely unknown functions. Phenotypic characterization of the dedA mutants and selenite consumption experiments strongly suggest that DedA is involved in the uptake of selenite.

Bacterial Proteins↗

PubMed1980

Stable isotope studies on the biosynthesis of lipoic acid in Escherichia coli.

A method has been developed for the gas chromatographic-mass spectrometric (GC-MS) identification of lipoic acid in tissue. The method consists of acid hydrolysis of the tissue to free the bound lipoic acid, methylene chloride extraction of the lipoic acid, and the subsequent chemical derivatization of the lipoic acid as methyl 6,8-bis(benzylthio)octanoate prior to GC-MS analysis. By use of this method of analysis, the incorporation of deuterium into lipoic acid by Escherichia coli growing on [methyl-2H3]acetate has been studied. The results clearly show that the lipoic acid is biosynthesized from octanoic acid with the loss of only one deuterium-containing position at C8. The deuterium incorporated at C6 of octanoic acid from the labeled acetate is retained. Since this deuterium is incorporated in the L configuration during fatty acid biosynthesis and it is known to have the D configuration in lipoic acid, it is concluded that an inversion of configuration occurs at C6 during the sulfur insertion.

Acetates↗

PubMed1995

Genetic diagnosis of haemophilia A of Chinese origin.

Genetic diagnosis of haemophilia A has been studied in two aspects. One is to directly identify the mutations in the factor VIII genes of the affected probands, and the other is to examine the usefulness of several intragenic factor VIII markers for gene tracking. Direct mutational analysis by PCR-SSCP (polymerase chain reaction--single-strand conformation polymorphism) has been accomplished previously in 87 haemophilia A patients, accounting for nearly 10% of cases in Taiwan. Of the 87 cases, 46% were with point mutations, short deletions or insertions, and most of the remaining were with gene inversion readily identified by Southern blotting. Further examination of 112 patients has estimated a 33% incidence for gene inversion in all the patients with haemophilia A, or 37% in severe cases. Since the direct mutational detection described above cannot be used in all Chinese families with haemophilia A, genetic markers were also investigated. The two CA repeat markers located at intron 13 (CA-13) and intron 22 (CA-22), respectively, were amplified and analysed simultaneously. Seven different alleles with 18-24 CAs have been identified for CA-13. Alleles of 20 and 21 CAs are the most common and their population frequency was 0.68 and 0.24, respectively. The CA-22 marker contained a repetition of (GT)n(AG)n as was identified in the white European but not in the Canadian population. Alleles with 25 and 26 GT/AGs account for 18% and 75% of this group of samples, respectively. The expected rate of heterozygosity for either CA markers was 68%, although a value of 57% was observed by haplotype analysis, indicating an association of the two repeat markers. Nevertheless, the study of 62 females showed that with the combined use of CA-13 and CA-22 with BclI, approximately 71% would be informative for these markers. This number may increase to 81% if XbaI polymorphism is added. We propose that a better genetic diagnosis procedure for Chinese individuals would be first to look for the inversion mutation, secondly for one of the intragenic markers, and then at the PCR-SSCP analysis.

Blotting, Southern↗

PubMed2002

Characterization of variant Salmonella genomic island 1 multidrug resistance regions from serovars Typhimurium DT104 and Agona.

Strains of multidrug-resistant Salmonella enterica serovar Typhimurium DT104 (DT104) and S. enterica serovar Agona (Agona) have been found to harbor Salmonella genomic island 1 (SGI1), a 43-kb genomic region that contains many of the drug resistance genes. Such strains are resistant to ampicillin (pse-1), chloramphenicol/florfenicol (floR), streptomycin/spectinomycin (aadA2), sulfonamides (sul1), and tetracycline [tet(G)] (commonly called the ACSSuT phenotype). All five resistance genes are found in a 13-kb multidrug resistance (MDR) region consisting of an unusual class I integron structure related to In4. We examined DT104 and Agona strains that exhibited other resistance phenotypes to determine if the resistance genes were associated with variant SGI1 MDR regions. All strains were found to harbor variant SGI1-like elements by using a combination of Southern hybridization, PCR mapping, and sequencing. Variant SGI1-like elements were found with MDR regions consisting of (i) an integron consisting of the SGI1 MDR region with the addition of a region containing a putative transposase gene (orf513) and dfrA10 located between duplicated qacEDelta1/sulI genes (SGI1-A; ACSSuTTm); (ii) an integron with either an aadA2 (SSu) or a pse-1 (ASu) cassette (SGI1-C and SGI1-B, respectively); (iii) an integron consisting of the SGI1-C MDR region plus an orf513/dfrA10 region as in SGI1-A (SGI1-D; ASSuTm; ampicillin resistance due to a TEM beta-lactamase); and (iv) an integron related to that in SGI1 but which contains a 10-kb inversion between two copies of IS6100, one which is inserted in floR (SGI1-E; ASSuT). We hypothesize that the MDR of SGI1 is subject to recombinational events that lead to the various resistance phenotypes in the Salmonella strains in which it is found.

Amino Acid Sequence↗

PubMed1999

Excision of IS492 requires flanking target sequences and results in circle formation in Pseudoalteromonas atlantica.

The gram-negative marine bacterium Pseudoalteromonas atlantica produces extracellular polysaccharide (EPS) that is important in biofilm formation by this bacterium. Insertion and precise excision of IS492 at a locus essential for extracellular polysaccharide production (eps) controls phase variation of EPS production in P. atlantica. Examination of IS492 transposition in P. atlantica by using a PCR-based assay revealed a circular form of IS492 that may be an intermediate in transposition or a terminal product of excision. The DNA sequence of the IS492 circle junction indicates that the ends of the element are juxtaposed with a 5-bp spacer sequence. This spacer sequence corresponds to the 5-bp duplication of the chromosomal target sequence found at all IS492 insertion sites on the P. atlantica chromosome that we identified by using inverse PCR. IS492 circle formation correlated with precise excision of IS492 from the P. atlantica eps target sequence when introduced into Escherichia coli on a plasmid. Deletion analyses of the flanking host sequences at the eps insertion site for IS492 demonstrated that the 5-bp duplicated target sequence is essential for precise excision of IS492 and circle formation in E. coli. Excision of IS492 in E. coli also depends on the level of expression of the putative transposase, MooV. A regulatory role for the circular form of IS492 is suggested by the creation of a new strong promoter for expression of mooV by the joining of the ends of the insertion sequence element at the circle junction.

Base Sequence↗

PubMed1999

High-resolution MR imaging of the asymptomatic Achilles tendon: new observations.

OBJECTIVE: Our aim was to describe the normal appearance of the Achilles tendon and peritendinous tissues in asymptomatic active volunteers using high-resolution MR imaging. MATERIALS AND METHODS: One hundred clinically asymptomatic Achilles tendons were imaged at 1.5 T with axial high-resolution T1-weighted gradient-echo (fast low-angle shot [FLASH]) and short inversion time inversion recovery (STIR) sequences. The tendons, peritendinous tissues, tendon insertions, and musculotendinous junctions were separately evaluated by two observers. RESULTS: The average anteroposterior diameter (+/-SD) of the asymptomatic Achilles tendons was 5.2+/-0.73 mm. The anterior margin was flat or concave in all, except for 10 tendons that showed mild convexity. A wave-like bulge, which shifted from lateral to medial in the craniocaudal direction, was detected in the anterior margin of 56 tendons. The signal intensity was heterogeneous in 45 tendons. In these tendons, distal stripes or punctate foci were seen. A small (3 mm) intermediate intensity intratendinous region thought to represent tendon degeneration was detected in four cases on FLASH images. The retrocalcaneal bursae contained a prominent fluid collection in 15 cases. The paratenon was visualized in all cases on both FLASH and STIR images. CONCLUSION: High-resolution MR imaging depicts the Achilles tendon and peritendinous soft tissues in great detail. The normal anatomy of the asymptomatic Achilles tendon is variable. We postulate that the variability may be a potential source of diagnostic misinterpretation.

Achilles Tendon↗