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PubMed1980

Trisomy 20pter = to q11 in a malformed boy from a t(13;20)(p11;q11) translocation-carrier mother.

A 3 1/2-year-old boy revealed moderate motor and mental retardation, normal growth, a congenital heart defect and multiple minor dysmorphic signs and anomalies including brachycephaly, orbital hypotelorism, upward slanting palpebral fissures, short and beaked nose, full cheeks, malformed auricles, hypoplastic external genitalia, rocker-bottom feet with prominent heels, and various minor radiologic anomalies of bones. An extra chromosome in his karyotype appeared to represent trisomy of the short arm of chromosome 20 due to a maternally inhherited balanced t(13;20)(p11;q11) translocation.

Abnormalities, Multiple↗
PubMed1980

Tertiary trisomy (22q11q),47,+der(22),t(11;22).

We describe a case of tertiary trisomy (22q11q) 47,XX,+der(22),(22pter = to 22q13 :: 11q25 = to 11qter) in a child with mental retardation, cleft palate, and congenital heart disease resulting from 3 : 1 meiotic nondisjunction in a maternal (11;22) translocation carrier. The clinical findings in previously reported cases are reviewed and compared with the features of reported patients with "partial trisomy 11q" and "trisomy 22" syndromes. Half of the ten reported families had additional balanced translocation carriers who may have an increased risk of having a liveborn child with an MCA/MR syndrome, although none have been reported to date.

Adolescent↗
PubMed1976

Cloning of calf thymus satellite I DNA in Escherichia coli.

The 1400 base pair repeat produced by digestion of calf satellite I DNA (phi = 1.714 g/cm3) with EcoRI, was cloned in E. coli. The hybrid plasmid (pGM 214) which contains the ColE1-Ap vector (pSF 2124) and the 1400 base pair fragment replicates stably in E. coli and can be amplified by chloramphenicol treatment. No clone was found in which more than one "repeat unit" of the satellite I DNA was present in the chimaera plasmid. Digestion of the original satellite I and the plasmid pGM 214 with R-SmaI shows that the satellite DNA replicated in E. coli is cleaved by the restriction endonuclease SmaI whereas the original satellite I DNA from calf thymus is not, suggesting that the satellite I contains a large amount of modified cytosine or guanosine, probably 5-methyl-cytosine. R-EcoRI* produces a number of fragments with the satellite I in the range of 300 base pairs to 1400 base pairs. A physical map of pGM 214 (and pSF 2124) with R-EcoRI, R-HincII, R-HindIII, R-SmaI, R-BamI and R-EclI was constructed. The 1400 base pair "repeat unit" in the pGM 214 is efficiently transcribed in vitro by purified RNA polymerase, starting from a pSF 2124 promoter. The restriction enzyme EclI produces a 350 base pair repeat with calf satellite II (phi = 1,722 g/cm3), whereas the satellite I is not cut by this enzyme.

Animals↗
PubMed1976

A cytoplasmic gene for partial suppression of a nuclear pleiotropic respiratory deficient mutant in the petite negative yeast Schizosaccharomyces pombe.

The nuclear pleiotropic respiratory-deficient mutant pet1 (previously M126) exhibits cytochromes aa3 and b deficiencies accompanied by loss of the oligomycin-sensitivity of the mitochondrial ATPase. The mutant pet1, unable to grow on glycerol, growth on glucose. The latter phenotypic trait symbolized by ANAS-D, exhibits a high frequency (2 to 4 X 10(5)) Of spontaneous suppression into Antimycin A-resistant strains. Mutagenesis with MnCl2 increases by a factor of 10(2) the frequency of ANAR-D derivatives. This suppression is partial since none of the suppressed strains is able to grow on glycerol even when respiratory functions and cytochromes activities are restored as in the pet1 [SUP2] strain. In the latter strain it is concluded that the extralocus suppressor gene [SUP2] is responsible for the ANAR-D trait. Tetrad analysis in a cross homozygous for pet1 demonstrates a non-Mendelian segregation pattern for the SUP2 suppressor gene. In stable diploids, homozygous for pet1, the [SUP2] suppressor exhibits a mitotic segregation pattern. Furthermore the transmission of the [SUP2] gene is decreased by ethidium bromide treatment. Therefore, the [SUP2] suppressor gene responsible for partial suppression of the nuclear pleiotropic phenotype in mutant pet1 is of cytoplasmic heredity.

Adenosine Triphosphatases↗
PubMed1993

Further characterization of the respiratory deficient dum-1 mutation of Chlamydomonas reinhardtii and its use as a recipient for mitochondrial transformation.

The respiratory deficient dum-1 mutant of Chlamydomonas reinhardtii fails to grow in the dark because of a terminal 1.5 kb deletion in the linear 15.8 kb mitochondrial genome, which affects the apocytochrome b (CYB) gene. In contrast to the wild type where only mitochondrial genomes of monomer length are observed, the dum-1 genomes are present as a mixture of monomer and dimer length molecules. The mutant dimers appear to result from head-to-head fusions of two deleted molecules. Furthermore, mitochondrial genomes of dum-1 were also found to be unstable, with the extent of the deletion varying among single cell clones from the original mutant population. The dum-1 mutant also segregates, at a frequency of ca. 4% per generation, lethal minute colonies in which the original deletion now extends at least into the adjacent gene encoding subunit four of NAD dehydrogenase (ND4). We have used the dum-1 mutant as a recipient to demonstrate stable mitochondrial transformation in C. reinhardtii employing the biolistic method. After 4 to 8 weeks dark incubation, a total of 22 respiratory competent colonies were isolated from plates of dum-1 cells bombarded with C. reinhardtii mitochondrial DNA (frequency 7.3 x 10(-7)) and a single colony was isolated from plates bombarded with C. smithii mitochondrial DNA (frequency 0.8 x 10(-7)). No colonies were seen on control plates (frequency < 0.96 x 10(-9)). All transformants grew normally in the dark on acetate media; 22 transformants were homoplasmic for the wild-type mitochondrial genome typical of the C. reinhardtii donor. The single transformant obtained from the C. smithii donor had a recombinant mitochondrial genome containing the donor CYB gene and the diagnostic HpaI and XbaI restriction sites in the gene encoding subunit I of cytochrome oxidase (COI) from the C. reinhardtii recipient. The characteristic deletion fragments of the dum-1 recipient were not detected in any of the transformants.

Animals↗
PubMed1993

A chloroplast DNA deletion located in RNA polymerase gene rpoC2 in CMS lines of sorghum.

Fertile lines of sorghum (Sorghum bicolor) were shown to differ from cytoplasmic male sterile (CMS) lines by the presence of a 3.8 kb HindIII chloroplast DNA fragment in the former and a smaller (3.7 kb) fragment in the latter. DNA/DNA hybridization studies showed that these two fragments are homologous. Fertile plants from S. versicolor, S. almum, S. halepense, and Sorghastrum nutans (Yellow Indiangrass) also have the 3.8 kb fragment, and CMS lines studied containing A1, A2 and A3 cytoplasms have the 3.7 kb fragment. The size difference between the two fragments was localized to a 1.0 kb SacI-HindIII fragment by restriction mapping. A 165 bp deletion, which is flanked by a 51 bp tandem repeat, was identified in the CMS lines by sequencing the clones. Comparison of the two sequences with those from maize, rice, tobacco, spinach, pea, and liverwort revealed that the deleted sequence is located in the middle of the RNA polymerase beta" subunit encoded by the gene rpoC2. The amino acid sequence deleted in the CMS lines is in a monocot-specific region which contains two protein motifs that are characteristic of several transcriptional activation factors, namely, a leucine zipper motif and an acidic domain capable of forming an amphipathic alpha-helix. Further studies designed to determine whether or not the deletion is involved in CMS of sorghum are underway.

Amino Acid Sequence↗
PubMed1993

Preferential extrachromosomal localization of exogenous DNA in transgenic silkworm Bombyx mori L.

Transgenic silkworms (Bombyx mori L.) were obtained by microinjection of plasmid pPrC-LTR1.5, which carris 1.5 DNA copies of Rous sarcoma virus (RSV) long terminal repeats (LTRs) inserted in the vector pBR322. The transgene was transmitted over the three generations obtained up to now. Most of the exogenous DNA failed to integrate into the genome and persisted as an extrachromosomal element that is subject to rearrangements. Plasmids carrying only part of the input DNA together with fragments of silkworm DNA were rescued from the transgenic animals. One of the rescued plasmids contained a sequence which belongs to a family of evolutionarily conserved repeated sequences.

Animals↗
PubMed1993

Identification of the entire set of transferred chloroplast DNA sequences in the mitochondrial genome of rice.

The entire set of transferred chloroplast DNA sequences in the mitochondrial genome of rice (Oryza sativa cv. Nipponbare) was identified using clone banks that cover the chloroplast and mitochondrial genomes. The mitochondrial fragments that were homologous to chloroplast DNA were mapped and sequenced. The nucleotide sequences around the termini of integrated chloroplast sequences in the rice mtDNA revealed no common sequences or structures that might enhance the transfer of DNA. Sixteen chloroplast sequences, ranging from 32 bases to 6.8 kb in length, were found to be dispersed throughout the rice mitochondrial genome. The total length of these sequences is equal to approximately 6% (22 kb) of the rice mitochondrial genome and to 19% of the chloroplast genome. The transfer of segments of chloroplast DNA seems to have occurred at different times, both before and after the divergence of rice and maize. The mitochondrial genome appears to have been rearranged after the transfer of chloroplast sequences as a result of recombination at these sequences. The rice mitochondrial DNA contains nine intact tRNA genes and three tRNA pseudogenes derived from the chloroplast genome.

Base Sequence↗
PubMed1994

The evolutionary origin of the 35 kb circular DNA of Plasmodium falciparum: new evidence supports a possible rhodophyte ancestry.

In common with other Apicomplexan parasites, Plasmodium falciparum carries two extrachromosomal DNAs, one of which, the 6 kb element, is undoubtedly mitochondrial. The second, generally referred to as the 35 kb circle, is of unknown provenance, but the nature and organization of its genetic content makes a mitochondrial association unlikely and the molecule has features reminiscent of plastid genomes. We now report the occurrence on the circle of an open reading frame specifying a predicted 470 amino acid protein that shares more than 50% identity with a gene currently known only on the plastome of red algae. This high degree of conservation confirms the 35 kb circle's plastid ancestry, and we speculate that it may have originated from the rhodoplast of an ancient red algal endosymbiont in the progenitor of the Apicomplexa.

Amino Acid Sequence↗
PubMed1991

RNA-protein interactions at transcript 3' ends and evidence for trnK-psbA cotranscription in mustard chloroplasts.

In vitro transcripts from the 3' flanking regions of mustard chloroplast genes were tested for protein binding in a chloroplast extract. Efficient and sequence-specific RNA-protein interaction was detected with transcripts of the genes trnK, rps16 and trnH, but not with the 3' terminal region of trnQ RNA. The transacting component required for specific complex formation is probably a single 54 kDa polypeptide. The protein-binding region of the rps16 3' terminal region was mapped and compared with that of the trnK transcript determined previously. Both regions reveal a conserved 7-mer UUUAUCU followed by a stretch of U residues. Deletion of the trnK 3' U cluster resulted in more than 80% reduction in the binding activity, and after deletion of both the U stretch and the 7-mer motif no binding at all was detectable. RNase protection experiments indicate that the protein-binding regions of both the rps16 and trnK transcripts correlate with the positions of in vivo 3' ends, suggesting an essential role for the 54 kDa binding protein in RNA 3' end formation. In the case of the trnK gene, evidence was obtained for read-through transcripts that extend into the psbA coding region, thus pointing to the possibility of trnK-psbA cotranscription.

Base Sequence↗
PubMed1991

Intercistronic group III introns in polycistronic ribosomal protein operons of chloroplasts.

A novel ribosomal protein operon in the Euglena gracilis chloroplast genome was characterized. It encodes the genes for ribosomal proteins S4 and S11 (rps4 and rps11). The coding region of the rps11 gene is interrupted by two introns of 107 and 100 bp. The introns belong to a distinct class known as group III introns. The major transcript from this operon was characterized as a fully spliced dicistronic rps4-rps11 mRNA by RNA blot analysis, primer extension sequencing, and cDNA cloning and sequencing. An additional 95 nucleotide (nt) group III intron was identified in the 123 nt rps4-rps11 intercistronic region. The identification of the intercistronic intron between the rps4 and rps11 genes was unexpected. Other RNA transcripts from regions of the genome that could potentially contain intercistronic introns were re-examined and two other intercistronic, group III introns were found. These are located in a large ribosomal protein operon between the genes for the ribosomal proteins L23 and L2, and between L14 and L5. There are at least 50 group III introns in the E. gracilis chloroplast genome. All but 6 are found in genes encoding protein components of the transcriptional and translational apparatus. The distribution of group III introns and the unusual location of intercistronic group III introns may reflect some aspect of gene expression, or provide some insight into the mechanism of their splicing.

Amino Acid Sequence↗