Results Of DNA Sequence Analysis Research Articles

Pregnant Iraqi women's exposure to certain efflux pump genes of highly pathogenic uropathogenic Escherichia coli was studied molecularly.

One hundred midstream urine samples were collected from pregnant women aged less than 20 to over 36 years suffering symptoms referred to as urinary tract infections (UTIs) from a private laboratory in Baghdad city. 90 of the urine samples gave a positive culture, and 10 gave a hostile culture. According to microscopic examination, cultural characteristics and biochemical tests, Escherichia coli was identified as the most causative agent 53(58.9%) that causing UTIs among all bacterial isolates, which confirmed the diagnosis by Vital Index of Traditional Environmental Knowledge (VITEK 2) systems and at final genetically by diagnostic gene( UidA ) gene. Genetic study including extraction of chromosomal DNA from 25 E.coli isolates which have multidrug resistance (MDR) against different antibiotics classes, then identification by UidA gene and detection of acrA,acrB genes that encoding for efflux pump proteins to all 25 E.coli isolates by conventional polymerase chain reaction (PCR) amplification technique with specific primer for each gene. The results showed the UidA gene identification found in all E.coli isolates, and the result of detection efflux pump genes showed that acrA and acrB genes were present together in all E.coli isolates. The results of DNA sequence analysis of E3 bacterial isolate showed that the diagnostic genes UidA and, acrA, acrB gene were 99% belonging to E. coli as found in the National Center for Biotechnology Information (NCBI). Keywords: Pregnant women, Urinary tract infection, E. coli,

The combination of ITS2 and psbA-trnH region is powerful DNA barcode markers for authentication of medicinal Terminalia plants from Thailand.

The dried fruits of Terminalia plant (Combretaceae) called "Samo" have been used as herbal medicine in Thai traditional medicine. Four "Samo" crude drugs, namely, Samo thai, Samo thed, Samo dee-ngu, and Samo phiphek, are used as the main ingredients in Triphala and Trisamo recipes. Their commercial products are available in processed and powdered form, but are difficult to authenticate by conventional methods. In this study, we aimed to discriminate species of genus Terminalia for the identification of their crude drugs by a DNA barcoding technique. A total of 208 closely related nucleotide sequences were obtained from nine Terminalia species collected from Thailand and the DDBJ/EMBL/GenBank database. An effective DNA barcode marker was selected from six DNA loci (matK, rbcL, psbA-trnH, ITS, ITS1, and ITS2) and their two-locus combination. All sequences were analyzed by three major methods: (1) BLAST search; (2) the genetic divergence method using Kimura 2-parameter (K2P) distance matrices; and (3) tree topology analysis based on the neighbor-joining method. Comparison of the six candidate DNA loci indicated that ITS identified Terminalia with 100% accuracy at the species and genus levels in the BLAST1 method. ITS2 showed the highest K2P variability. The data from the single markers and the two-locus combinations revealed that only the two-locus combinations, namely, the combinations of rbcL, ITS, ITS1, and ITS2 with psbA-trnH, clearly discriminated all the species. From the results of DNA sequence analysis and the three methods, ITS2 is recommended for the identification of Terminalia species to supplement psbA-trnH.

Expression and anticancer activity analysis of recombinant human uPA1‑43-melittin.

The present study is focused on expression of a target fusion protein which can be used in ovarian cancer target therapy. It aimed to construct human urokinase-type plasminogen activator (uPA)(1-43)-melittin eukaryotic expression vector to express recombinant human uPA(1-43)-melittin (rhuPA(1-43)-melittin) in P. pastoris and to detect its anticancer effects on ovarian cancer cells. The DNA sequences that encode uPA1-43 amino acids and melittin were synthesized according to its native amino acid sequences and consequently inserted into pPICZαC vector. Then uPA1-43-melittin -pPICZαC was transformed into P. pastoris X-33, and rhuPA(1-43)-melittin was expressed by methonal inducing. The bioactivities of recombinant fusion protein were detected with inhibition effects on growth of ovarian cancer cells, cell cycle detection and TUNEL assay. The results of DNA sequence analysis of the recombinant vector uPA(1-43)-melittin -pPICZαC demonstrated that the DNA encoding human uPA 1-43 amino acids and 1-26 amino acids of melittin was correctly inserted into the pPICZαC vector. After being induced by methonal, fusion protein with molecular weight 7.6 kDa was observed on the basis of SDS-PAGE and western blot analysis. The recombinant protein was able to suppress growth of SKOV3, induce cell cycle arrest and apoptosis of SKOV3 cells. The fusion protein does not have any obvious toxicity on normal tissues. RhuPA(1-43)-melittin was successfully expressed in P. pastoris. Taking uPA(1-43) amino acids specifically binding to uPAR as targeted part of fusion protein, and making use of antitumor activity of melittin, the recombinant fusion protein it was able to inhibit growth of ovarian tumors and to be applied for effective targeted treatment.

Taxonomy of Desmodesmus serratus (Chlorophyceae, Chlorophyta) and related taxa on the basis of morphological and DNA sequence data

Fawley M.W., Fawley K.P. and Hegewald E. 2011. Taxonomy of Desmodesmus serratus (Chlorophyceae, Chlorophyta) and related taxa on the basis of morphological and DNA sequence data. Phycologia 50: 23–56. DOI: 10.2216/10-16.1The green alga Desmodesmus serratus is a common small Desmodesmus species. The highly variable morphology among strains and natural populations suggested that this taxon was in need of revision using a combination of molecular and morphological characters. Thirty-six isolates that were assigned to D. serratus on the basis of morphology or that were known to be closely related to D. serratus on the basis of the results of DNA sequence analysis were examined. These isolates were evaluated by light microscopy, electron microscopy, and phylogenetic analysis of DNA sequences from the nuclear ribosomal internal transcribed spacer (ITS) regions, nuclear 5.8S ribosomal DNA, and the plastid rbcL gene. Results of the analyses of ITS and rbcL sequence data were congruent. On the basis of the results of these analyses, we propose the new species Desmodesmus itascaensis, Desmodesmus perdix, Desmodesmus serratoides, Desmodesmus pseudoserratus, and Desmodesmus santosii. Two of these species, D. perdix and D. pseudoserratus, possess morphologies identical to that of D. serratus. However, these species were all clearly separated on the basis of the results of DNA sequence analysis. The new species as well as D. serratus form a monophyletic lineage that is allied with the small, spineless species, Desmodesmus costato-granulatus, Desmodesmus lunatus, Desmodesmus elegans, Desmodesmus ultrasquamatus, and Desmodesmus regularis.

Analysis of two VP60 capsid protein genes of rabbit hemorrhagic disease virus from viruses obtained from the same farm

Two distinct clones of the VP60 capsid protein gene of rabbit hemorrhagic disease virus were amplified from mixed liver tissue of rabbits collected from the same farm in the Xinjiang Uygur Autonomous Region of China in 2002. The results of DNA sequence analysis showed that the length of the VP60 gene in the first clone was 1,740bp, similar to other VP60 genes. The length of the VP60 gene in the second clone was only 1,536bp. The two clones were predicted to encode 579 and 511 amino acids, respectively.

Abstract 824: Comparison of the high risk HPV detection methods (HC II, DNA Chip, and luminex-based assay) in cervical lesion of Korean women

Abstract The detection of human papillomavirus (HPV) of female genital tract is very important, several HPV DNA detection methods have been developed during the last decade. In previous report, we introduced luminex-based HPV genotyping assay that is combined PCR amplification. In this study, we compared performances to detect high risk HPV types in hybrid capture 2 (HC II), DNA Chip, and luminex-based assay. A total of 330 cervical swabs from Cervical Cancer Early Diagnostic Clinic, Seoul St. Mary's Hospital were investigated. DNA was extracted from a single sample and HPV DNA detection assays were performed on the same specimen with 3 strategies and confirmed by DNA sequencing. Among 330 cervical swabs, 230 were HPV positive, 100 were negative. HPV detection rates of Luminex, HC II and DNA Chip in 330 specimens were 65.2%, 61.2% and 68.8%, respectively. The results of DNA sequence analysis, accuracy of Luminex, HC II and DNA Chip was 91.2%, 82.7% and 80.9%, respectively. HPV DNA infection slightly increase with severity of disease in cytologic and histologic diagnosis, there is no correlation between HPV, because HPV DNAs were detected in many samples with normal in this study. Conclusively in HPV detection comparison, DNA Chip had relatively high detection rate than Luminex and HC II, but Luminex had the highest accuracy for HPV DNA detection. These results indicate that the Luminex-based assay has more accurate performance than DNA Chip and HC II assay in the detection of HPV infections. We suggest that Luminex-based assay may be useful method for detecting of HPV infection clinically. Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 824.

Lack of Chlamydophila pneumoniae and predominance of Alloiococcus otitidis in middle ear fluids of children with otitis media with effusion

Objective To investigate the presence of Chlamydophila pneumoniae and other bacterial pathogens in middle ear effusion samples obtained from children with otitis media with effusion (OME). Materials and methods Twenty-eight children (mean age 7.03; standard deviation 2.18) with OME unresponsive to medical therapy were included in the study. All of the children underwent ventilation tube insertion under general anesthesia. Eighteen patients were bilaterally affected whereas 10 children had unilateral disease. The middle ear fluids (46 samples in total) were collected during ventilation tube insertion, and were evaluated subsequently for the presence of C. pneumoniae and other bacterial pathogens using polymerase chain reaction (PCR). Results Although all samples were negative for C. pneumoniae, bacterial DNA was detected in 21 of 46 samples. Overall 40% of the patients (4/10) with unilateral involvement, and 61% of the patients (11/18) with bilateral involvement were positive for bacterial DNA. In 6 patients with bilateral OME bilateral samples were positive, whereas 5 patients with bilateral OME showed only unilateral positivity. According to the results of DNA sequencing analysis, all of the positive samples harbored only one bacterial species. In 12 of 46 samples Alloiococcus otitidis DNA (26%), in 7 Haemophilus influenzae DNA (15%), in one Streptoccoccus pneumoniae DNA (2%) and in one Moraxella catarrhalis DNA (2%) were present. Conclusions Our findings support that C. pneumoniae does not seem to have a role in OME in children whereas A. otitidis was found to be more frequent than the other common pathogens. Further studies are required to elucidate the exact pathogenetic role of these microorganisms in OME.

Ser217Cys mutation in the Ig II domain of FGFR3 in a Chinese family with autosomal dominant achondroplasia

Achondroplasia (ACH) is the most common form of skeletal dysplasia characterized by disproportionately short stature, lumbar lordosis, relative macrocephaly and other skeletal anomalies resulting from a defect in the maturation of the chondrocytes in the growth plate of the cartilage. The combined frequency of the disease has been estimated to be 1 in 15 000 live births.

食品由来酵母の同定におけるＤＮＡ塩基配列解析法と表現性状試験との比較

The identification of 20 strains of yeasts isolated from foods by means of DNA sequence analysis with two kinds of universal primers for the rDNA region was examined, and the results were compared with those of the conventional phenotyping test using API 20C AUX. In the analysis of the 26S region, all 20 yeast strains tested were identified at the species level. In the ITS1 region, 16 strains were also classified at the species level. In addition, all results of DNA sequence analysis were consistent with those of the phenotyping test at the genus level. Furthermore, DNA sequence analysis was able to identify causative yeasts observed in two suspect foods, though phenotyping tests alone failed to identify them.

A re-evaluation of the genera Beckerella and Ptilophora (Gelidiales, Rhodophyta) based on molecular and morphological data

Because the merger of the genera Prilophora and Beckerella (Gelidiales, Rhodophyceae) into the single genus Ptilophora has not been universally accepted, we have reassessed this proposal using both molecular and morphological data. Phylogenetic analyses of DNA sequences for rbcL and large-subunit ribosomal DNA from 36 and 24 species of Gelidiales, respectively, place species of Beckerella and Ptilophora in a single, strongly supported clade. Morphological observations of vegetative structure in both genera confirm a morphological synapomorphy characterized by four concentric layers of different tissue types. Results of DNA sequence analyses indicate that Beckerella is paraphyletic with respect to Ptilophora, and constraining species of Beckerella and Prilophora to form separate monophyletic clades required a large (10.2%) penalty to parsimony. Absence of surface proliferations has traditionally been the morphological character-state difference used to separate species of Beckerella from Ptilophora, but we have found such proliferations in four species of Beckerella, including the generitype B. pinnatifida. These results support the congeneric status of Beckerella with the earlier-described Ptilophora.

Fractals in DNA sequence analysis

Fractal methods have been successfully used to study many problems in physics, mathematics, engineering, finance and even in biology. There has been an increasing interest in unravelling the mysteries of DNA; for example, how can we distinguish coding and noncoding sequences and the problems of classification and evolution relationship of organisms are key problems in bioinformatics. Although much research has been carried out by taking into consideration the long-range correlations in DNA sequences and the global fractal dimension has been used in these works by other people, the models and methods are somewhat rough and the results are not satisfactory. In recent years, our group has introduced a time series model (statistical point of view) and a visual representation (geometrical point of view) to DNA sequence analysis. We have also used fractal dimension, correlation dimension, the Hurst exponent and the dimension spectrum (multifractal analysis) to discuss problems in this field. In this paper, we introduce these fractal models and methods and the results of DNA sequence analysis.

Xeronemataceae, a New Family of Asparagoid Lilies from New Caledonia and New Zealand

Summary. A new family of Asparagales, Xeronemataceae, is described. This small family of two species is native to New Zealand and was formerly included by several authors in Phormiaceae, to which they are grossly similar. However, they differ in a number of significant ways, and the results of DNA sequence analysis strongly support them as occupying an isolated position as sister to a clade composed of most of the higher Asparagales, thus making their description as a new family appropriate. Xeronema Brongn. & Gris is a poorly known genus of two species. It was initially thought to be monotypic with the only species being X. moorei Brongn. & Gris from New Caledonia. However, in 1924 another species, X. callistemon W. R. B. Oliv., was discovered on inaccessible inland cliff areas of the Poor Knights Islands, situated 15 miles off the northeastern coast of New Zealand (Oliver 1925, 1926). Xeronema callistemon was later found on the outlying New Zealand island Taranga (Cranwell 1933) but has never been recorded growing naturally in mainland New Zealand. The two species are rather similar in morphology, but in general X. callistemon is a larger plant than X. moorei, and there are differences in flower structure; for example, X. callistemon has a more persistent style and shorter, more tapering seeds (Moore 1957). Both species have leathery, unifacial equitant (ensiform) leaves and congested racemes bearing elongate, crimson flowers that all face upwards. The stamens are highly exserted and have persistent filaments. All parts of the flowers are red or orange, including the pollen; they could be bird or butterfly pollinated. The flowers have six free tepals, six free stamens with versatile anthers dehiscing by longitudinal introrse slits and a secretory tapetum. Pollen is monosulcate, with a finely reticulate exine, and normally boat-shaped with an elliptical sulcus (Fig. 1A), also reported by Cranwell (1953) and Schulze (1982). In material examined here (with standard SEM techniques), we found rare trichotomosulcate grains (Fig. iB), with a Y-shaped sulcus, among predominantly monosulcate grains (Fig. 1A). The ovary is superior, trilocular, with axile placentation and several crassinucellate ovules per locule. Prominent, branched, highly vascularised septal nectaries extend from the ovary base to openings around the style base (Rudall unpublished). Calcium oxalate raphides are present in idioblasts throughout all tissues, but styloid crystals are absent (Prychid & Rudall 1999). The fruit is purplish, with numerous black seeds with papillate surfaces (Oliver 1926).

How microbial ancient DNA, found in association with human remains, can be interpreted.

The analysis of the DNA of ancient micro-organisms in archaeological and palaeontological human remains can contribute to the understanding of issues as different as the spreading of a new disease, a mummification process or the effect of diets on historical human populations. The quest for this type of DNA, however, can represent a particularly demanding task. This is mainly due to the abundance and diffusion of bacteria, fungi, yeasts, algae and protozoans in the most diverse environments of the present-day biosphere and the resulting difficulty in distinguishing between ancient and modern DNA. Nevertheless, at least under some special circumstances, by using rigorous protocols, which include an archaeometric survey of the specimens and evaluation of the palaeoecological consistency of the results of DNA sequence analysis, glimpses of the composition of the original microbial flora (e.g. colonic flora) can be caught in ancient human remains. Potentials and pitfalls of this research field are illustrated by the results of research works performed on prehistoric, pre-Columbian and Renaissance human mummies.

Evolution of glutamine synthetase genes is in accordance with the neutral theory of molecular evolution.

Evolution of glutamine synthetase gene is discussed on the results of DNA sequence analysis of the gene. Thirty DNA sequences of various organisms spanning from prokaryotes to eukaryotes were collected from the DNA data banks and translated first, they were aligned next, then evolutionary distances were computed, and molecular phylogeny was finally estimated. The results of the alignment reveal that functionally important regions of glutamine synthetase have been evolutionarily more conserved than the remaining regions. The evolutionary distances computed also show that the rate of synonymous substitution is higher than that of nonsynonymous substitution. These are well in accordance with the neutral theory of molecular evolution. Besides, the molecular phylogeny obtained shows that the origin of glutamine synthetase gene is much earlier than the divergence between eukaryotes and prokaryotes, suggesting that the gene is one of the oldest genes functioning now.

New ultra-micro high-performance liquid chromatographic method for determining the γ chain composition of hemoglobin F in normal adults

The difficulty in isolating the minute quantity of Hb F (<1%) present in the red blood cells of normal adults greatly complicates the determination of its γ chain composition. We have developed a rapid ultra-micro high-performance liquid chromatographic (HPLC) method and used it to analyze the γ chain composition of Hb F in 47 adults with Hb F levels between 0.1–3.4%. The method involves the isolation of Hb F from as little as 50 μl of whole blood on an analytical size cation-exchange HPLC column, followed by concentration in a Centricon micro concentrator unit and by reversed-phase HPLC analysis. The entire procedure can be completed in one day and 3–4 analyses can be made simultaneously. We reanalyzed the blood samples from 22 subjects with known β-globin gene cluster haplotypes, and confirmed the association of high, low, and very low Gγ levels with haplotypes A, B, and C, respectively. Also included are the results of DNA sequence analyses of the Gγ and β promoters, and of the locus-control-region hypersensitive site-2 (LCR-HS-2) of the β-globin gene cluster in five subjects homozygous for haplotypes A, B or C; the data obtained failed to provide a satisfactory explanation for all the variations in the Gγ levels that have been observed.

Cloning and structural-functional studies for 7.5k promoter of Tiantan strain of vaccinia virus.

The 7.5k promoter of vaccinia virus Tiantan strain has been cloned by DNA polymerase chain reaction (PCR) method. Results of DNA sequencing analysis showed that in comparison with P7.5k of WR strain, three site mutations and 7 bp of natural deletion existed in the 155 bp fragment of P7.5k of Tiantan strain; four of 7 base pairs deleted were in the late transcriptional initiation region. Although the total mutation rate was high to 6.45%, these two 7.5k promoters of Tiantan strain & WR strain were all early-late promoters and not obviously different in their activities and functional phases. The results above confirmed further that it is a mechanism to keep their genetic stability that some genes of vaccinia virus have multiple transcriptional initiation sites and produce many mRNA with heterologous 5' ends.

DNA Sequence of Genes for Detoxification of Fusaric Acid, a Wilt‐inducing Agent Produced by Fusarium Species

AbstractIsolation and nucleotide sequence determination of fusaric acid‐detoxification genes are described in this paper. For screening the genes, bacteria collected from soil were positively selected in a selective medium containing fusaric acid. The capability of fusaric acid‐resistant isolates to detoxify the toxin was assayed by examining the survival of tomato callus cells in culture filtrates prepared from the bacterial culture, in the presence of fusaric acid. The isolate (HY‐1) showing the highest detoxification was selected and identified as Klebsiella oxytoca. Chromosomal DNA of this isolate was digested with Bam HI and shotgun‐cloned to fusaric acid‐sensitive E. coli. The DNA fragment carrying fusaric acid‐detoxification genes was further shortened by enzyme digestion and the open reading frames in the fragment were analyzed by determining total nucleotide sequences of the fragment. Finally, three open reading frames were shown to be essential for expressing the detoxification of fusaric acid. These frames possessed a single promoter sequence at the upstream region of the first open reading frame. Northern blot analysis showed that these genes were polycistronically transcribed to express the fusaric acid detoxification, strongly supporting th results of DNA sequence analysis.

DNA sequence analysis of X-ray inducedAdh null mutations inDrosophila melanogaster

The mutational spectrum for 28 X-ray induced mutations and 2 spontaneous mutations, previously determined by genetic and cytogenetic methods, consisted of 20 multilocus deficiencies (19 induced and 1 spontaneous) and 10 intragenic mutations (9 induced and 1 spontaneous). One of the X-ray induced intragenic mutations was lost, and another was determined to be a recombinant with the allele used in the recovery scheme. The DNA sequence of two X-ray induced intragenic mutations has been published. This paper reports the results of DNA sequence analysis of the remaining intragenic mutations and a summary of the X-ray induced mutational spectrum. Only one of the X-ray induced mutations is a single base change, a C to G transversion (AdhnLA80). Therefore, the mutational spectrum of X-ray induced mutations consists predominantly of deletions that are observed to range in size from two base pairs to deletions of a large number of loci as determined by genetic complementation analysis. The combination of DNA sequence analysis with genetic complementation analysis shows a continuous distribution in size of deletions rather than two different types of mutations consisting of deletions and "point mutations." Sequencing is shown to be essential for detecting intragenic deletions. Of particular importance for future studies is the observation that all of the intragenic deletions consist of a direct repeat adjacent to the break-point with one of the repeats deleted.

Molecular and biophysical analysis of herbicide-resistant mutants of Chlamydomonas reinhardtii: structure-function relationship of the photosystem II D1 polypeptide.

Plants and green algae can develop resistance to herbicides that block photosynthesis by competing with quinones in binding to the chloroplast photosystem II (PSII) D1 polypeptide. Because numerous herbicide-resistant mutants of Chlamydomonas reinhardtii with different patterns of resistance to such herbicides are readily isolated, this system provides a powerful tool for examining the interactions of herbicides and endogenous quinones with the photosynthetic membrane, and for studying the structure-function relationship of the D1 protein with respect to PSII electron transfer. Here we report the results of DNA sequence analysis of the D1 gene from four mutants not previously characterized at the molecular level, the correlation of changes in specific amino acid residues of the D1 protein with levels of resistance to the herbicides atrizine, diuron, and bromacil, and the kinetics of fluorescence decay for each mutant, which show that changes at two different amino acid residues dramatically slow PSII electron transfer. Our analyses, which identify a region of 57 amino acids of the D1 polypeptide involved in herbicide binding and which define a D1 binding niche for the second quinone acceptor, QB of PSII, provide a strong basis of support for structural and functional models of the PSII reaction center.

Amino acid substitutions in subunit 9 of the mitochondrial ATPase complex of Saccharomyces cerevisiae. Sequence analysis of a series of revertants of an oli1 mit- mutant carrying an amino acid substitution in the hydrophilic loop of subunit 9.

This work concerns a biochemical genetic study of subunit 9 of the mitochondrial ATPase complex of Saccharomyces cerevisiae. Subunit 9, encoded by the mitochondrial oli1 gene, contains a hydrophilic loop connecting two transmembrane stems. In one particular oli1 mit- mutant 2422, the substitution of a positively charged amino acid in this loop (Arg39----Met) renders the ATPase complex non-functional. A series of 20 revertants, selected for their ability to grow on nonfermentable substrates, has been isolated from mutant 2422. The results of DNA sequence analysis of the oli1 gene in each revertant have led to the recognition of three groups of revertants. Class I revertants have undergone a same-site reversion event: the mutant Met39 is replaced either by arginine (as in wild-type) or lysine. Class II revertants maintain the mutant Met39 residue, but have undergone a second-site reversion event (Asn35----Lys). Two revertants showing an oligomycin-resistant phenotype carry this same second-site reversion in the loop region together with a further amino acid substitution in either of the two membrane-spanning segments of subunit 9 (either Gly23----Ser or Leu53----Phe). Class III revertants contain subunit 9 with the original mutant 2422 sequence, and additionally carry a recessive nuclear suppressor, demonstrated to represent a single gene. The results on the revertants in classes I and II indicate that there is a strict requirement for a positively charged residue in the hydrophilic loop close to the boundary of the lipid bilayer. The precise location of this positive charge is less stringent; in functional ATPase complexes it can be found at either residue 39 or 35. This charged residue is possibly required to interact with some other component of the mitochondrial ATPase complex. These findings, together with hydropathy plots of subunit 9 polypeptides from normal, mutant and revertant strains, led to the conclusion that the hydrophilic loop in normal subunit 9 extends further than previously suggested, with the boundary of the N-terminal membrane-embedded stem lying at residue 34. The possibility is raised that the observed suppression of the 2422 mutant phenotype in class III revertants is manifested through an accommodating change in a nuclear-encoded subunit of the ATPase complex.