Giant cell arteritis-related aortitis with positive or negative temporal artery biopsy: a French multicentre study

Objective: To compare the clinical presentation and outcome of giant cell arteritis (GCA)-related aortitis according to the results of temporal artery biopsy (TAB).Method: Patients with GCA-related aortitis diagnosed between 2000 and 2017, who underwent TAB, were retrospectively included from a French multicentre database. They all met at least three American College of Rheumatology criteria for the diagnosis of GCA. Aortitis was defined by aortic wall thickening > 2 mm on computed tomography scan and/or an aortic aneurysm, associated with an inflammatory syndrome. Patients were divided into two groups [positive and negative TAB (TAB+, TAB-)], which were compared regarding aortic imaging characteristics and aortic events, at aortitis diagnosis and during follow-up.Results: We included 56 patients with TAB+ (70%) and 24 with TAB- (30%). At aortitis diagnosis, patients with TAB- were significantly younger than those with TAB+ (67.7 ± 9 vs 72.3 ± 7 years, p = 0.022). Initial clinical signs of GCA, inflammatory parameters, and glucocorticoid therapy were similar in both groups. Coronary artery disease and/or lower limb peripheral arterial disease was more frequent in TAB- patients (25% vs 5.3%, p = 0.018). Aortic wall thickness and type of aortic involvement were not significantly different between groups. Diffuse arterial involvement from the aortic arch was more frequent in TAB- patients (29.1 vs 8.9%, p = 0.03). There were no differences between the groups regarding overall, aneurism-free, relapse-free, and aortic event-free survival.Conclusion: Among patients with GCA-related aortitis, those with TAB- are characterized by younger age and increased frequency of diffuse arterial involvement from the aortic arch compared to those with TAB+, without significant differences in terms of prognosis.

[Reliability and validity of a workbook for assessment of professional competencies of internal medicine residents]

INTRODUCTION

Though several assessment tools for resident professional skills based on workplace direct observation have been validated, they remain scarcely used in France. The objective of this study was to evaluate the reliability and the validity of a workbook including several assessment forms for different components of the professional competency.

METHODS

Three assessment forms have been tested over a period of 6 months in a multicentric study including 12 French internal medicine departments: the French version of the mini-CEX, an interpersonal skills assessment form (OD_CR) and the multisource feedback form (E_360). Reliability has been assess using the intra-class correlation coefficient (ICC) and the Cronbach alpha coefficient. Arguments for validity have been provided looking at the ability of the forms to detect an increase in the scores over time and according to the level of experience of the resident.

RESULTS

Twenty-five residents have been included. The Cronbach alpha was of 0.90 (n=70) with the mini-CEX, 0.89 with the OD_CR (n=62) and 0.77 with the E_360 (n=86). ICC showed a wide variation according to the items of the mini-CEX and the OD-CR probably due to the poor number of observations performed by residents. The scores of most of the items of these two forms increased between M1 and M6. The scores of the E_360 were high: 7.3±0.8 to 8.3±2.4 (maximum 9) and did not vary according to the level of experience.

CONCLUSION

This study suggest that it would be difficult to ensure a sufficient reliability for professional skills assessment using these tools given our available current human and material resources. However, these assessment forms could be added to the resident portfolio as supports for the debriefing in order to document their progression during their formation.

Rhabdomyolyse massive révélant une maladie de McArdle

INTRODUCTION

McArdle's disease is an autosomal recessive glycogenosis caused by deficiency of muscle glycogen phosphorylase resulting in glycogen accumulation in the skeletal muscle. Typically, McArdle's disease is characterized by exercise intolerance with muscle cramps and myoglobinuria.

CASE REPORT

We report a 20-year-old woman with massive rhabdomyolysis and acute renal failure revealing a McArdle's disease.

DISCUSSION

Although muscle impairment is constant in McArdle's disease, massive rhabdomyolysis with severe acute renal failure has been rarely reported as a presenting feature. The mechanisms and therapeutic implications of renal injury are discussed.

[A case of alcohol-induced ketoacidosis?]

We report a case of severe ketoacidosis. Initially the patient showed metabolic acidosis, the anion gap was positive and there was neither hyperlactatemia nor intoxication with acid substances. As the rate of glycemia was high (17.8 mmol/L), the diagnosis of diabetic ketoacidosis was proposed. Under treatment with continuous IV injection of insulin, hypoglycemia (1.8 mmol/L) appeared rapidly, while urine bioreactive test was positive for ketonuria, but negative for glycosuria. We finally concluded that it was an alcoholic ketoacidosis. The history of the patient confirmed the diagnosis : chronic alcoholism with recent increased of alcohol intake which provoked vomiting and fasting. This case report shows the difficulty in distinguishing between alcoholic ketoacidosis and diabetic ketoacidosis. We discuss the diagnostic strategy and particularly biologic data in the light of pathophysiologic mechanism of alcoholic ketoacidosis.

Identification and characterization of a mitochondrial thioredoxin system in plants

Plants possess two well described thioredoxin systems: a cytoplasmic system including several thioredoxins and an NADPH-dependent thioredoxin reductase and a specific chloroplastic system characterized by a ferredoxin-dependent thioredoxin reductase. On the basis of biochemical activities, plants also are supposed to have a mitochondrial thioredoxin system as described in yeast and mammals, but no gene encoding plant mitochondrial thioredoxin or thioredoxin reductase has been identified yet. We report the characterization of a plant thioredoxin system located in mitochondria. Arabidopsis thaliana genome sequencing has revealed numerous thioredoxin genes among which we have identified AtTRX-o1, a gene encoding a thioredoxin with a potential mitochondrial transit peptide. AtTRX-o1 and a second gene, AtTRX-o2, define, on the basis of the sequence and intron positions, a new thioredoxin type up to now specific to plants. We also have characterized AtNTRA, a gene encoding a protein highly similar to the previously described cytosolic NADPH-dependent thioredoxin reductase AtNTRB but with a putative presequence for import into mitochondria. Western blot analysis of A. thaliana subcellular and submitochondrial fractions and in vitro import experiments show that AtTRX-o1 and AtNTRA are targeted to the mitochondrial matrix through their cleavable N-terminal signal. The two proteins truncated to the estimated mature forms were produced in Escherichia coli; AtTRX-o1 efficiently reduces insulin in the presence of DTT and is reduced efficiently by AtNTRA and NADPH. Therefore, the thioredoxin and the NADPH-dependent thioredoxin reductase described here are proposed to constitute a functional plant mitochondrial thioredoxin system.

Wheat mitochondria ccmB encodes the membrane domain of a putative ABC transporter involved in cytochrome c biogenesis

Assembly of cytochromes c is mediated by different proteins depending on the organism and organelle considered. In land plants, mitochondria follow a pathway distinct from that of yeast and animal mitochondria, more similar to that described for alpha- and gamma-proteobacteria. Indeed, in plant mitochondria, four genes were identified based on the similarities of their products with bacterial proteins involved in c-type cytochrome maturation. We report the characterisation of one of these mitochondrial genes in Triticum aestivum, TaccmB, which is proposed to encode a subunit of an ABC transporter. The transcript extremities were mapped and cDNA sequencing revealed 42 C to U editing positions in the 618 nucleotide long coding region. This high editing rate affects the identity of 32 amino acids out of 206. Antibodies directed against wheat CcmB recognise a 28 kDa protein in an enriched inner mitochondrial membrane protein fraction, a location which is in agreement with the high hydrophobicity of the protein and its function as a putative transmembrane domain of an ABC transporter involved in cytochrome c and c1 biogenesis in plant mitochondria.

CCME, a nuclear-encoded heme-binding protein involved in cytochrome c maturation in plant mitochondria

The maturation of c-type cytochromes requires the covalent attachment of the heme cofactor to the apoprotein. For this process, plant mitochondria follow a pathway distinct from that of animal or yeast mitochondria, closer to that found in alpha- and gamma-proteobacteria. We report the first characterization of a nuclear-encoded component, namely AtCCME, the Arabidopsis thaliana orthologue of CcmE, a periplasmic heme chaperone in bacteria. AtCCME is targeted to mitochondria, and its N-terminal signal peptide is cleaved upon import. AtCCME is a peripheral protein of the mitochondrial inner membrane, and its major hydrophilic domain is oriented toward the intermembrane space. Although a AtCCME (Met(79)-Ser(256)) is not fully able to complement an Escherichia coli CcmE mutant strain for bacterial holocytochrome c production, it is able to bind heme covalently through a conserved histidine, a feature previously shown for E. coli CcmE. Our results suggest that AtCCME is important for cytochrome c maturation in A. thaliana mitochondria and that its heme-binding function has been conserved evolutionary between land plant mitochondria and alpha-proteobacteria.

Mitochondrial localization of AtOXA1, an arabidopsis homologue of yeast Oxa1p involved in the insertion and assembly of protein complexes in mitochondrial inner membrane

Components of some protein complexes present in the inner membrane of mitochondria are encoded in both nuclear and mitochondrial genomes, and correct sorting and assembly of these proteins is necessary for proper respiratory function. Recent studies in yeast suggest that Oxa1p, a protein conserved between prokaryotes and eukaryotes, is an essential factor for protein sorting and assembly into membranes. We previously identified AtOXA1, an Arabidopsis homologue of OXA1 by functional complementation of a yeast oxa1- mutant. In this study, we investigated the genomic organization of AtOXA1 and localization of the AtOXA1 protein. Characterization of the AtOXA1 genomic region indicated that the gene consists of 10 exons and is located on chromosome V. A database search also revealed another gene coding for a putative protein homologous to AtOXA1 on chromosome II. Transient expression of a green fluorescent protein (GFP) fusion in suspension-cultured tobacco cells showed that AtOXA1 is targeted into mitochondria by its N-terminal presequence. Antibodies raised against AtOXA1 recognized a 38-kDa intrinsic protein of the inner mitochondrial membrane. Thus, localization of AtOXA1 in the mitochondrial inner membrane, together with our previous complementation experiment in yeast, suggested that it is a functional homologue of Oxa1p.

Transcription initiation and RNA processing in the mitochondria of the red alga Chondrus crispus: convergence in the evolution of transcription mechanisms in mitochondria

The mitochondrial DNA (mt DNA) of the red alga Chondrus crispus is shown to be transcribed into two large RNA molecules. These primary transcripts are cleaved once, at the level of a tRNA, then the resulting products are processed via multiple maturation events into either mono- or poly-cistronic RNAs. Transcripts were detected for all genes and open reading frames, except for rps11 and orf172. For both transcription units the initiation of transcription was mapped by in vitro RNA capping and primer extension experiments within inverse repeated sequences at the north pole of the molecule. Consistent with primer extension mapping, putative promoter motifs sharing significant similarities with both chicken and Xenopus mitochondrial promoters were found in the C. crispus mitochondrial genome. Altogether C. crispus mitochondrial DNA appears to be transcribed as animal mtDNA is, suggesting that transcription mechanisms in mitochondria are dependent on the overall organization of the mitochondrial genome irrespective of the eukaryotic phylogeny.

Molecular mechanisms of cytochrome c biogenesis: three distinct systems

The past 10 years have heralded remarkable progress in the understanding of the biogenesis of c-type cytochromes. The hallmark of c-type cytochrome synthesis is the covalent ligation of haem vinyl groups to two cysteinyl residues of the apocytochrome (at a Cys-Xxx-Yyy-Cys-His signature motif). From genetic, genomic and biochemical studies, it is clear that three distinct systems have evolved in nature to assemble this ancient protein. In this review, common principles of assembly for all systems and the molecular mechanisms predicted for each system are summarized. Prokaryotes, plant mitochondria and chloroplasts use either system I or II, which are each predicted to use dedicated mechanisms for haem delivery, apocytochrome ushering and thioreduction. Accessory proteins of systems I and II co-ordinate the positioning of these two substrates at the membrane surface for covalent ligation. The third system has evolved specifically in mitochondria of fungi, invertebrates and vertebrates. For system III, a pivotal role is played by an enzyme called cytochrome c haem lyase (CCHL) in the mitochondrial intermembrane space.

Cis- and trans-splicing and RNA editing are required for the expression of nad2 in wheat mitochondria

In wheat mitochondria, the gene coding for subunit 2 of the NADH-ubiquinone oxidoreductase (nad2) is divided into five exons located in two distant genomic regions. The first two exons of the gene, a and b, lie 22 kb downstream of exons c, d, and e, on the same DNA strand. All introns of nad2 are group II introns. A trans-splicing event is required to join exons b and c. It involves base pairing of the two precursor RNAs in the stem of domain IV of the intron. A gene coding for tRNA(Tyr) is located upstream of exon c. In addition to splicing processes, mRNA editing is also required for the correct expression of nad2. The mature mRNA is edited at 36 positions, distributed over its five exons, resulting in 28 codon modifications. Editing increases protein hydrophobicity and conservation.

The rapeseed mitochondrial gene encoding a homologue of the bacterial protein Ccl1 is divided into two independently transcribed reading frames

In the rapeseed mitochondrial genome we identified sequences that have a high similarity to those of a bacterial gene involved in the biogenesis of cytochromes c designated ccl1. The structure of this gene is quite unusual. In rapeseed mitochondria, the ccl1-homologous (orf577) sequence is divided into two parts, which are at least 45 kb apart. These two parts are transcribed separately and their transcripts are edited similarly to the homologous transcripts of wheat and Oenothera. However it was impossible to identify a mature transcript covering the whole coding region, a result that excludes a trans-splicing event. No other copy of this gene was found in either the nuclear genome or the mitochondrial genome. The protein product of orf577 is present in rapeseed mitochondria. These results raise the possibility that this divided gene might be functional and active in rapeseed mitochondria through a novel mechanism of gene expression.

Complete sequence of the mitochondrial DNA of the rhodophyte Chondrus crispus (Gigartinales). Gene content and genome organization

The complete nucleotide sequence of the circular mitochondrial (mt) DNA from the red alga Chondrus crispus was determined (25,836 nucleotides, A+T content 72.1%). Fifty one genes were identified. They include genes encoding three subunits of the cytochrome oxidase (cox1 to 3), apocytochrome b (cob), seven subunits of the NADH dehydrogenase complex (nad1 to 6, nad4L), two ATPase subunits (atp6 and atp9), three ribosomal RNAs (rrn5, srn and lrn), 23 tRNAs and four ribosomal proteins (rps3, rps11, rps12 and rpl16). Two subunits of the succinate dehydrogenase complex (sdhB and sdhC), usually found on nuclear genomes, are also located on the mtDNA of C. crispus. One group IIb intron is inserted in the tRNAIle gene. Six potentially functional open reading frames were identified, four of them having counterparts among green plant mtDNAs. The use of a modified genetic code and the absence of RNA editing, previously reported for the cox3 gene, appears as a general characteristic of this molecule. Mitochondrial genes are encoded on both DNA strands, in two opposite major transcriptional directions, suggesting the existence of two main transcriptional units. Two long and stable stem-loops were identified in intergenic regions, which are believed to be involved with transcription and replication. The main structural features of this genome are compared with the overall organization of mtDNAs and are discussed in view of the evolution of mitochondria.

A gene proposed to encode a transmembrane domain of an ABC transporter is expressed in wheat mitochondria

In a study of transcribed regions of the wheat mitochondrial genome, we identified an open reading frame of 720 bp, which was consequently designated orf240. The amino acid sequence deduced from orf240 shows a high level of similarity with HelC, a protein essential for c-type cytochrome biogenesis in the photosynthetic purple bacterium Rhodobacter capsulatus. HelC is part of a putative heme ABC transporter. An open reading frame homologous to orf240 is present in the mitochondrial genome of Marchantia polymorpha. The wheat gene is expressed as an mRNA of 2.8 kb, which is further processed to smaller transcripts. The transcript is highly edited, with 36 C to U modifications found in the coding region of all cDNAs sequenced. RNA editing is responsible for changes in 14% of the amino acids specified by the transcript.

Nucleotide sequence of the cox3 gene from Chondrus crispus: evidence that UGA encodes tryptophan and evolutionary implications

We present the nucleotide sequence of the gene encoding subunit 3 of cytochrome c oxidase in Chondrus crispus, the first report on a mitochondrial gene from a red alga. Amino acid alignment with homologous proteins shows that tryptophan is specified by UGA, as in the mitochondrial code of most organisms other than green plants. However, phylogenetic analyses of cox3 amino acid and nucleotide sequences indicate that C. crispus COX3 is related to the green-plant mitochondrial lineage. No RNA editing was detected on the corresponding transcript. As the only known photosynthetic eukaryotes that both share an immediate mitochondrial ancestor with green plants and exhibit features characteristic of non-plant mitochondria, ie, a small-sized mitochondrial genome and a modified genetic code, rhodophytes may be thought of as an intermediate evolutionary link at the root of the green-plant mitochondrial lineage.

A gene involved in the biogenesis of c-type cytochromes is co-transcribed with a ribosomal protein gene in wheat mitochondria [corrected]

Sequence analysis of a transcribed region of the wheat mitochondrial (mt) genome revealed two open reading frames (orfs) coding for proteins of 589 and 174 amino acids. Both genes are co-transcribed in a 2.6-kb RNA. The largest orf codes for a hydrophobic protein which bears similarity to a bacterial protein involved in the biogenesis of c-type cytochromes. Its corresponding RNA sequence is fully edited at 34 positions. The second orf encodes a protein homologous to the amino-terminal third of E. coli ribosomal protein S1, corresponding to the ribosome-binding domain of this protein. Its RNA sequence is edited at four positions, one of the edits creating a stop codon. The presence of both proteins in wheat mitochondria was demonstrated using specific antibodies raised against fusion proteins obtained in E. coli from the corresponding cDNAs.

Expression of the wheat mitochondrial nad3-rps12 transcription unit: correlation between editing and mRNA maturation

In plant mitochondria, RNA editing involves the conversion of cytidines in the genomic DNA into uridines in the corresponding RNA. Analysis of cDNAs prepared by reverse transcription of mitochondrial RNAs has shown that partially edited RNAs are present in wheat mitochondria. The extent of this partial editing as well as its potential influence on the corresponding protein sequence were studied along with the expression of a wheat mitochondrial locus. The sequence, expression, and RNA editing of the wheat mitochondrial transcription unit containing four open reading frames (nad3, rps12, orf299, orf156), all cotranscribed into a same predominant precursor RNA, have been studied. The product of orf156 is an 18-kD mitochondrial membrane protein of unknown function, whereas the product of orf299 could not be detected and this sequence seems to be a pseudogene. Sequences of cDNA clones derived by the polymerase chain reaction technique show that nad3, rps12, and orf156 transcripts are edited, whereas orf299 is not edited, except for a sequence identical to part of the coxII gene. Analysis of cDNA clones obtained from the precursor RNA shows the presence of a large number of partially edited nad3-rps12 transcripts with no evident polarity for the editing process. This shows that RNA editing is a post-transcriptional event. In addition, study of partial editing at the level of precursor, mature, and polysomal transcripts shows that mainly mature, completely edited sequences are used for translation. Deletions of a nucleotide at editing sites were observed in a number of cDNA clones, suggesting that C----U RNA editing in plant mitochondria would be achieved by nucleotide replacement.

RNA editing in wheat mitochondria results in the conservation of protein sequences

RNA editing is a process that results in the production of a messenger RNA with nucleotide sequences that differ from those of the template DNA, and provides another mechanism for modulating gene expression. The phenomenon was initially described in the mitochondria of protozoa. Here we report that RNA editing is also required for the correct expression of plant mitochondrial genes. It has previously been proposed that in plant mitochondria there is a departure from the universal genetic code, with CGG specifying tryptophan instead of arginine. This was because CGG codons are often found in plant mitochondrial genes at positions corresponding to those encoding conserved tryptophans in other organisms. We have now found, however, wheat mitochondrial gene sequences containing C residues that are edited to U residues in the corresponding mRNA sequences. In this way, CGG codons can be changed to UGG codons in the mRNA so that tryptophan may be encoded according to the universal genetic code. Furthermore, for each codon modification resulting from a C----U conversion that we studied, we found a corresponding change in the amino acid that was encoded. RNA editing in wheat mitochondria can thus maintain genetic information at the RNA level and as a result contribute to the conservation of mitochondrial protein sequences among plants.

Sequence and distribution of IS866, a novel T region-associated insertion sequence from Agrobacterium tumefaciens

We have identified a new insertion sequence, IS866, located in the auxin synthesis gene TA iaaH of Tm4, a wide host range biotype III octopine/cucumopine type Agrobacterium tumefaciens strain with two T regions on its tumor-inducing (Ti) plasmid, TA, and TB. IS866 is 2716 bp long, has inverted repeats of 27 bp with three mismatches, and generates 8-bp direct repeats upon integration. In addition to IS866, pTiTm4 carries two copies of a related element, IS867, associated with TA and TB, respectively. A systematic study of 92 virulent Agrobacterium strains has shown that among the three biotypes all octopine/cucumopine and vitopine biotype III isolates contain IS866-like elements. The various octopine/cucumopine Ti plasmids always carry IS866 and IS867 at the same position as in pTiTm4. The chromosomes of the bacteria which contain these Ti plasmids also carry IS866 and IS867 copies but in varying numbers and locations.

Nucleotide sequence, evolutionary origin and biological role of a rearranged cytokinin gene isolated from a wide host range biotype III Agrobacterium strain

A DNA fragment with homology to the cytokinin (ipt) gene from biotype I Agrobacterium tumefaciens strain Ach5 was cloned from the Ti plasmid of the wide host range biotype III Agrobacterium strain Tm-4 and sequenced. The fragment contains an intact ipt coding sequence. However, the 3' non-coding region of this ipt gene is rearranged due to a 0.9 kb deletion fusing it to the 3' coding region of the neighbouring gene 6a, most of which was found to be deleted. The Tm-4 ipt gene is strongly related to the partially deleted ipt gene of the limited host range biotype III strain Ag162. To test its biological activity, the Tm-4 ipt gene was inserted into a specially constructed, disarmed Ti vector lacking tzs and tested on tobacco, where the rearranged ipt gene induced shoot formation. The cloned Tm-4 ipt gene was mutated with Tn5 and the intact gene on the wild-type Tm-4 Ti plasmid was replaced by the mutated gene. The resulting strain was avirulent on tobacco but normally virulent on the natural host of the wild-type strain Tm-4, grapevine. As the biotype I 6b gene diminishes the effect of a corresponding ipt gene, a larger Tm-4 fragment carrying both the ipt gene and an adjacent 6b-like gene was also tested on tobacco and compared with the Tm-4 ipt fragment alone and with an ipt and 6b/ipt fragment derived from Ach5. The Tm-4 6b gene diminishes the effect of the Tm-4 ipt gene, showing the Tm-4 6b gene to be active as well. The Tm-4 6b/ipt combination is less effective than the Ach5 combination. These results provide further insight into the molecular basis of the host range differences between limited host range and wide host range biotype III Agrobacterium strains and show that the WHR cytokinin gene, although active, does not significantly contribute to tumour formation on the natural host of the WHR biotype III strains, grapevine.

Isolation and functional analysis of a set of auxin genes with low root-inducing activity from an Agrobacterium tumefaciens biotype III strain

A new type of root-inducing iaa gene set was cloned from the Ti plasmid of the biotype III Agrobacterium tumefaciens strain Tm-4. These iaa genes are characterized by a very low DNA homology with the well-characterized iaa gene set, iaaM and iaaH, of the "common DNA" region of the biotype I strain Ach5 and by a low root-inducing activity.The biological activities of both iaa gene sets were compared by transferring each into a disarmed Ti vector and by testing the resulting strains on Nicotiana rustica leaf discs, decapitated Datura stramonium stems, tomato plants and Kalanchoë daigremontiana. Tm-4 iaa genes have a reproducibly weaker root-inducing ability on Nicotiana rustica, induce very little tumour growth on decapitated Datura plants or on tomato plants and do not induce roots on Kalanchoë daigremontiana. The Tm-4 iaa region was mapped by λ:: Tn5 transposon mutagenesis and tested on Nicotiana rustica. These tests combined with complementation experiments map the iaa genes to a 4.5-kb region.The Tm-4 iaa genes were able to complement the corresponding Ach5 iaa genes on Nicotiana rustica, indicating that the differences between these genes are quantitative rather than qualitative. Complementation experiments on Kalanchoë showed the iaaM gene of Tm-4 responsible for the overall weak auxin activity of the intact iaa set. In view of the observed structural and functional differences we propose to call the Tm-4 iaa genes TB-iaaM and TB-iaaH and the Ach5 iaa genes A-iaaM and A-iaaH.

The intergenic region between the Vicia faba chloroplast tRNA(CAALeu) and tRNA(UAALeu) genes contains a partial copy of the split tRNA(UAALeu) gene

A cluster of three tRNA genes located on fragment Bam6a from Vicia faba chloroplast DNA has been sequenced: it contains the genes for tRNA(CAALeu), tRNA(UAALeu) and tRNA(Phe). The two tRNA(Leu) genes are separated by 443 bp and are transcribed divergently from different DNA strands. The intergenic region contains a series of short repeats and a partial copy of the split tRNA(UAALeu) gene which includes 100 bp of the 5' flanking region, 35 bp of the 5'exon and the first 42 bp of the intron. It is possible that some of these duplications occurred upon the rearrangement of the two tRNA(Leu) genes in broad bean (and in pea) or upon the deletion of one copy of the inverted repeat, since in all other higher plant chloroplast genomes studied so far these two tRNA(Leu) genes are located far apart on the genome, one being in the inverted repeat region, the other one in the large single copy region. The tRNA(Phe) and tRNA(UAALeu) are encoded by the same DNA strand, and separated by 110 bp.

Cultured T cells from patients with T cell chronic lymphocytic leukemia demonstrate a normal phenotype

Peripheral blood mononuclear cells from eight patients with the rare T-cell form of chronic lymphocytic leukemia were isolated and cultured with Interleukin-2 (IL-2). In all but one case, cultured T-cells (CTC) were established. Various culture conditions were tested for their effectiveness; feeder layers proved valuable for expanding the cultures to large volumes. The CTC remained IL-2 dependent. Analysis of surface determinants on these CTC showed a polyclonal proliferation of T-cells. The distribution of subset markers in the patients' CTC population had completely changed in comparison to the "fresh" peripheral blood cell population but was similar to CTC initiated from healthy donors. Our data suggest that the patients' few contaminating normal T-lymphocytes expanded in culture, while the malignant cells were unresponsive to IL-2. This conclusion is supported by growth characteristics and morphology of the CTC.

Chloroplast DNA variation between species of Triticum and Aegilops. Location of the variation on the chloroplast genome and its relevance to the inheritance and classification of the cytoplasm

Restriction endonuclease analysis revealed interspecific and intraspecific variation between the chloroplast DNAs and therefore between the cytoplasms of 14 selected species of Triticum and Aegilops. Eleven distinct chloroplast DNA types were detected, the differences between them residing in the varied combination of a relatively few DNA alterations.The variation was simple enough for chloroplast DNA analysis to be used as a basis for the identification and classification of the Triticum and Aegilops cytoplasms. There was good agreement with the classification based on analysis of the phenotypic effects of the cytoplasm when combined with the T. aestivum nucleus in nuclear-cytoplasmic hybrids (Tsunewaki et al. 1976). There was however no correlation between specific chloroplast DNA alterations and any of the phenotypic effects known to be associated with specific cytoplasms.Although the diploid species examined included all those which have been suggested as possible donors of the cytoplasm and the B genome to T. aestivum, none of the chosen accessions belonged to the same cytoplasmic class as T. aestivum itself, except that of the tetraploid T. dicoccoides. Therefore, none of the diploid accessions analysed was the B genome donor. The analyses did however support several other suggestions which have been made concerning wheat ancestry. Scoring the different chloroplast DNA types according to the rarity of their banding patterns indicated that four of the eleven cytoplasms are of relatively recent origin.The DNA alterations most easily detectable by the limited comparison of the eleven Triticum/Aegilops chloroplast DNA types using only 4 endonucleases were insertions and deletions. These ranged between approximately 50 bp and 1,200 bp in size and most of them were clustered in 2 segments of the large single-copy region of the genome. Only two examples of the loss of restriction endonuclease sites through possible point mutations were observed. No variation was detected in the inverted repeat regions. Several of the deletions and insertions map close to known chloroplast protein genes, and there is also an indication that the more variable regions of the chloroplast genome may contain sequences which have allowed DNA recombination and rearrangement to occur.