Southeast Asian Mitochondrial DNA Analysis Reveals Genetic Continuity of Ancient Mongoloid Migrations

Human mitochondrial DNAs (mtDNAs) from 153 independent samples encompassing seven Asian populations were surveyed for sequence variation using the polymerase chain reaction (PCR), restriction endonuclease analysis and oligonucleotide hybridization. All Asian populations were found to share two ancient AluI/DdeI polymorphisms at nps 10394 and 10397 and to be genetically similar indicating that they share a common ancestry. The greatest mtDNA diversity and the highest frequency of mtDNAs with HpaI/HincII morph 1 were observed in the Vietnamese suggesting a Southern Mongoloid origin of Asians. Remnants of the founding populations of Papua New Guinea (PNG) were found in Malaysia, and a marked frequency cline for the COII/tRNA(Lys) intergenic deletion was observed along coastal Asia. Phylogenetic analysis indicates that both insertion and deletion mutations in the COII/tRNA(Lys) region have occurred more than once.     

PATMAT: a searching and extraction program for sequence, pattern and block queries and databases

A program has been developed that provides molecular biologistswith multiple tools for searching databases, yet uses a verysimple interface. PATMATcan use protein or (translated) DNAsequences, patterns or blocks of aligned proteins as queriesof databases consisting of amino acid or nucleotide sequences,patterns or blocks. The ability to search databases of blocksby ‘on-the-fly’ conversion to scoring matrices providesa new tool for detection and evaluation of distant relationships.PATMAT uses a pull-down, menu-driven interface to carry outits multiple searching, extraction and viewing functions. Eachquery or database type is recognized, reported, and the appropriatesearch carried out, with matches and alignments reported inwindows as they occur. Any of the high scoring matches can beexported to a file, viewed and recalled as a query using onlya few keystrokes or mouse selections. Searches of multiple databasefiles are carried out by user selection within a window. PATMATruns under DOS; the searching engine also runs under UNIX.     

Complete moles have paternal chromosomes but maternal mitochondrial DNA

Summary Complete hydatidiform moles contain only paternal chromosomes. To learn more of their origin, we used restriction endonuclease site polymorphisms found in the parental mitochondrial DNAs to demonstrate that moles contain exclusively maternal mitochondrial DNA. Thus, moles must arise from the fusion of one or two sperm with a mature but anucleate ovum.     

Isolation of a plant glycoprotein involved with control of intercellular recognition

A recognition molecule was isolated from stigmas of S-allele genotype S₂S₂ of Brassica oleracea var. capitata L. After Sephadex chromatography, it eluted as a single symmetrical peak during diethylaminoethane-cellulose chromatography. A high degree of purity was affirmed by: sedimentation as a single peak during ultracentrifugation through 5 to 20% sucrose gradients; elution as a single peak from Sephadex G-100; visualization as a single band which stains with Coomassie blue and periodic acid Schiff reagent after electrophoresis on polyacrylamide gels. Other criteria supporting the conclusion that it is a glycoprotein are: (a) the highly purified preparation is anthrone-positive and has a Lowry protein to anthrone-positive carbohydrate ratio of 1.3; (b) the preparation contains arabinose, galactose, glucose, and mannose, although it is not precipitated by concanavalin A; (c) the immunological properties of the molecule are lost following protease treatment, and it has a molecular weight of 90,000 by Sephadex gel-filtration analysis and 54,500 by velocity sedimentation analysis.     

Turnover of endogenous, microinjected, and sequestered protein in Xenopus oocytes

Pulse-labeled oocyte proteins were found to have a maximum average half-life of 73 h. In general, larger peptides underwent degradation at a faster rate than smaller peptides. In this respect, oocytes are similar to most other cells. Microinjected ¹²⁵I-labeled bovine serum albumin (BSA) was degraded over a 40 h period with a half-life of 20–30 h, regardless of the method of protein labeling, culture medium employed, size of oocyte microinjected, or hormonal history of the oocyte. The last two results, if applicable to oocyte proteins in general, imply that protein catabolism is constant throughout the later stages of oogenesis and that growth is primarily regulated by a stimulation of anabolism. Individual proteins microinjected into oocytes undergo rates of degradation consistent with turnover rates obtained in other systems. Sequestered ¹²⁵I-labeled BSA is only partially (40%) degraded, which indicates that, unlike microinjected ¹²⁵I-labeled BSA, it has access to a cytoplasmic compartment (yolk platelets?) within which it is relatively stable.     

The semisynthesis of fragments corresponding to residues 66-104 of horse heart cytochrome c.

We describe the N epsilon-acetimidylation of horse heart cytochrome c with retention of biological activity, the cleavage of the modified protein by CNBr, the separation of the fragments, and their further side-chain protection. We describe the manipulation of the amino acid sequences of the fragments by stepwise semisynthetic methods. We have prepared fragments corresponding to residues 66-78 and 66-79 of the protein, as well as the [Asp66] analogue of fragment 66-79. We have prepared the natural sequence and the [o-fluoro-Phe82] analogue of the fragment corresponding to residues 81-104 of the protein, and the [N epsilon-trifluoroacetyl-Lys79], the [N epsilon-dinitrophenyl-Lys79] and the [S-acetamidomethyl-Cys79] analogues of fragment 79-104, and the [N epsilon-Cbz-Lys81] analogue of fragment 80-104. We have coupled back the fragments of natural sequence to form a semisynthetic fragment corresponding to residues 66-104 of the protein. Modified fragments were also coupled to give analogues of the 66-104-residue sequence. In every case the homoserine residue representing methionine-80 was removed from the C-terminus of the 66-80-residue fragment and replaced by methionine on the N-terminus of the 81-104 residue fragment during the preparation of the fragments for coupling. The semisynthetic fragments are ready for specific deprotection and further coupling. We have coupled one such fragment to the (1-65)-peptide to produce semisynthetic [Hse65]cytochrome c. The product has satisfactory characteristics on chemical analysis, and on assay of its biological activity.     

Chemical and physical properties of mammalian mitochondrial aminoacyl-transfer RNAs. I. Molecular weights of mitochondrial leucyl- and methionyl-transfer RNAs.

The sedimentation and electrophoretic properties of Syrian hamster cytosolix and mitochondrial methionyl- and leucyl- +RNAs have been compared under denaturing conditions. Mitochondrial leucyl-tRNA could be separated into three species by chromatography on RPC-5. Their apparent molecule weights as determined by polyacrylamide slab gel elecltrophoresis were 23 000 for one species and 24 000 for the other two compared to the five cytosolic leucyl-tRNA species whose apparent molecular weights ranged from 26 000 to 28 000. Mitochondrial leucyl-tRNAs sedimented more slowly than their cytosolic counterparts, again indicating a lower molecular weight. The apparent molecular weights of the mitochondrial methionyl-tRNAs were identical or only slightly lower than their cytosolic counterparts as determined by polyacrylamide slab gel electrophoresis but both mitochondrial methionyl-tRNA and formylmethionyl-tRNA sedimented slightly more slowly than cytolsolic methionyl-tRNA. It is suggested that mitochondrial tRNAs fall into the size range of other t RNAs and might be uniform in size.     

Chemical and physical properties of mammalian mitochondrial aminoacyl-transfer RNAs. II. Analysis of 7-methylguanosine in mitochondrial and cytosolic aminoacyl-transfer RNAs.

The 7-methylguanosine (m7G) content of two individual mitochondrial tRNAs, labelled in the aminoacyl moiety was assayed by the specific cleavage of the tRNA at this nucleotide followed by electrophoretic analysis to identify the 3'-terminal fragment of the tRNA. Neither Syriam hamster mitochondrial tRNALeu nor tRNAMet were found to contain m7G. In contrast, cytosolic tRNAMetS were cleaved indicating the presence of m7G, apparently 27--28 and 29 nucleotides from their 3' terminus. Cystolic tRNALeu was not cleaved. These results are discussed in relationship to the reported low content of methylated nucleosides in mitochondrial 4 S RNA.     

Quantitation of submandibular proteins resolved from normal individuals and children with cystic fibrosis

Submandibular secretions collected from children with cystic fibrosis (CF) showed increased protein concentration (milligrams/milliliter) and increased amylase specific activity (units/milligram of protein) relative to normal secretions. These differences between normal (N) and CF secretions were as follows: protein, 1.25 ± 0.51 (N), 1.75 ± 0.35 (CF) (P < 0.02); and amylase, 58 ± 18 (N), 80 ± 19 (CF) (P < 0.001). To determine the basis for elevated protein in CF saliva, several major proteins resolved by polyacrylamide disc gel electrophoresis were quantitated by densitometry. These included four phosphoproteins (PP), serum albumin, an acid phosphatase-containing fraction, amylase, and an unidentified protein referred to as PI-7.1. Together, these proteins comprise greater than 75% of the total protein in the secretion. Differences in individual protein concentrations (milligrams/milliliter) resolved from normal and CF secretions, respectively, were as follows: PP₂, 0.02 ± 0.01, 0.03 ± 0.02 (NS, not significant); PP₃, 0.06 ± 0.04, 0.05 ± 0.03 (NS); acid phosphatase fraction, 0.06 ± 0.04, 0.12 ± 0.07 (P < 0.05); amylase, 0.09 ± 0.04, 0.27 ± 0.16 (P < 0.01); and pI-7.1, 0.04 ± 0.02, 0.13 ± 0.08 (P < 0.02). Amylase, the most significant contributor to the elevated protein, comprised 26% of the total protein of normal secretions and 38% of the total protein of CF secretions. Thus, our results do not support the concept of a generalized increase in all organic components in CF submandibular secretions but, rather, increases in specific proteins, namely amylase, component pI-7.1, and an acid phosphatase-containing fraction.