Mycoplasma–like Organisms Associated with a Grapevine Yellows Disease Occurring in Italy

Transmission electron microscopy of tissues from Vitis vinifera L. plants, naturally infected with a yellows disease similar to flavescence dorée (FD), revealed the presence of pleomorphic mycoplasmalike organisms (MLOs). These occurred in varying concentrations in mature sieve tube elements of leaf veins. Generally the concentration was very low, although large populations of MLOs were found colonizing almost the entire lumen of two cells. The micro–organisms varied considerably in size, shape and electron opacity. Spherical, oval and filamentous forms were recognized. The bodies showed the typical ultrastructural details of other known plant pathogenic MLOs. They were bounded by a smooth trilaminar membrane and contained ribosome–likegranules and DNA–like strands.     

CAG Repeats in Various Organisms Studied by Southern Blot Analysis

A 90-nucleotide (CAG)₃₀,single-stranded DNA was used to probe Southern blots inorder to indicate the quantity and distribution of longCAG repeats in selected genomes. Bovine and rat genomeswere found to contain a particularly high content of CAGrepeats, while the repeats were comparatively rare inthe human genome. A particularly strong signal in thebovine genome was due to a CAG repeat associatedwith the 1.709 satellite. A similar element wasfound in goat and musk, but not in the otherartiodactyls tested, suggesting that this particular CAGrepeat developed some 10-20 million years ago withina 3.8-kb unit presently belonging to thesatellite element and that this unit has latermultiplied in the genome. Single-copy repeats could bediscerned in yeast, but not in mammals. Thus the probedid not detect specific repeats in patients withCAG repeat diseases.     

Analysis of the equine lymphocyte antigen system by Southern blot hybridization

Fourteen Standardbred horses homozygous for one of six equine lymphocyte antigen (ELA) specificities (A1, A3, A4, A5, A6, or A10) were analyzed by Southern blot hybridization using DNA probes derived from the mouse major histocompatibility complex (MHC). Total genomic DNA from peripheral lymphocytes was digested with the restriction enzymes Hind III, Pvu II, or Eco RI. Twenty-three to thirty-three bands were generated for individual horses with the class I cDNA probe. The resulting band patterns revealed 12-14 nonpolymorphic fragments, which is consistent with the highly conservedQa/Tla genes seen in other species. The remaining 10–19 bands displayed significant polymorphism; no two animals had identical band patterns when studied with all three enzymes. The polymorpism was markedly decreased between animals of the same ELA serotypes. Unique bands were identified in both Al horses and all four A6 animals. Pvu II digestions of lymphocyte DNA were hybridized with mouse MHC class II probes. A cDNA probe for theE gene revealed only a single nonpolymorphic band. In contrast, a cDNA probe for theH-2 A locus displayed three to five strong bands in each animal with polymorphism that was most pronounced between horses of different ELA serotypes. Genomic DNA probes forAandE genes both revealed multiple polymorphic bands. However, cross-hybridization between these two probes prevented distinction betweenA andE equivalent loci. The reduced polymorphism evident within ELA specificities is consistent with the concept that the equine lymphocyte antigen system includes two families of closely linked MHC genes.     

Analysis of the rat major histocompatibility system by Southern blot hybridization

The organization of the rat major histocompatibility complex, RT1, was studied at the DNA level by Southern blot hybridization. Genomic DNA from eight different RT1 congenic rat strains was digested by various restriction enzymes and was hybridized under stringent conditions with probes of mouse class I and class II H-2 genes. Few cross-hybridizing DNA fragments, showing no polymorphism, were seen with class II A alpha and A beta probes. The class I probes allowed for the distinction of about 8 to 19 cross-hybridizing bands, which exhibited extensive polymorphism. With the use of five RT1 recombinants, about 20% of the DNA fragments could be mapped to the RT1.A region, which codes for the ubiquitously expressed class I antigens, and about 80% to the RT1.C region-determining class I-like antigens, which are different from RT1.A antigens with respect to tissue distribution, restriction function in immune responses, and allograft rejection. The number of class I genes present in the rat genome and the possible relationship of RT1.C to H-2Qa, Tla of the mouse are discussed.     

Sorghum lysine-rich cultivar verification by SDS-PAGE and Southern blot

The aim of this study was to assess the genetic variability among lysine-rich cultivars of sorghum (IS 21702; CVS B65, G 1058, G205 and CVS 549) and to compare with low lysine cultivar White Martin and a chemically induced high lysine mutant P721O. The lysine-rich cultivars contain approximately 1.5 to 2 times more lysine when compared to low-lysine cultivar. Sodium-dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of kafirins showed the absence of both 25.3 kD and 25.9 kD α-kafirins in lysine rich cultivars IS 21702, G 1058 and CV 365 and only the 25.9 kD protein was not present in G 205 compared with a low-lysine cultivar White Martin and with a chemically induced high-lysine mutant P721O. Southern blot analysis with RsaI enzyme gave significantly different banding pattern indicating the absence of 1.0 kb band in lysine-rich cultivars IS 21702, G 1058 and CVS 365 compared to White Martin indicating genetic variability among these cultivars. The detected variability among kafirins both in SDS-PAGE and Southern blot could be effectively used as markers in selection of lysine-rich cultivars for further use in breeding programme.     

嗜热真菌的分类研究一半知菌

根据嗜热真菌生境特点,从采集的600多份标本中分离鉴定到嗜热真菌15种,其中分离获得半知菌8种。对8种半知菌的形态特征进行了系统综合描述。     

Chemical Composition of Phloem Exudate of Mycoplasma–infected Apple Trees

Abstract Phloem exudate was obtained by incision from different apple cultivars affected by apple proliferation disease. The exudate was analyzed by high–performance liquide chromatography (HPLC), some compounds also by thin–layer chromatography, gel filtration chromatography and polyacrylamide gel electrophoresis. Sorbitol and sucrose were the most prevalent sugar, alcohol and sugar, respectively, while stachyose, raffinose, fructose, and myo–inositol were present to a much lower extent. Glucose was absent or occurred at very low concentrations only. All common amino acids with the exception of arginine and cysteine were detected, aspartic acid and glutamic acid together with the corresponding amides being predominant. Citric acid and malic acid werether major organic acids while shikimic, succinic and fumaric acid were present at considerably lower amounts. The inorganic constituents were (in decreasing order) potassium, magnesium, sodium, sulphate, chloride, phosphate, calcium, and nitrate. Approximately 100 ppm protein were found consisting mainly of two major fractions with a molecular weight of 110,000 and 28,000 Dalton, respectively. Only two lipid classes were detected which were represented by 0.4 ppm β–sitosterol and by 50 ppm of a sterylester with a long chain fatty acid moiety. DNA and RNA could not be found, but all RNA nucleotides were present and also UPD–glucose, which was predominant. The significance of the results obtained for culturing mycoplasma–like organisms (MLO_s), is discussed.     

Blame it on Southern,but it's a western blot

Edwin M. Southern is a professor emeritus at the University of Oxford. He is perhaps best known for development of the “Southern blot” (Dr. Southern was at the University of Edinburgh when he wrote his landmark paper). The Southern blot provided a scientific breakthrough by allowing scientists to detect a particular DNA sequence without first purifying it from the rest of the genome; the basic method involves the transfer of the DNA to a membrane, followed by detection with a specific probe. Although few people perform Southern blots as originally carried out by Southern, due in part to the more recent technique of the polymerase chain reaction, the basic concept continues to play an important role in molecular biology.     

Taxonomic Studies on Some Species of Diatoma

Six species and four varieties of Diatoma (D. hiemale (Roth) Heib. , D. maximum (Grun.) Fricke, D. mesodon (Ehr.) Kuetz. , D. moniliforme Kuetz. , D. tenue Ag., D. vulgare Bory and its varieties) were studied using optical microscope and scanning electron microscope. Their taxonomic problems were discussed as well.     

节腹泥蜂族分类研究进展

本文对节腹泥蜂族的分类研究现状进行了总结。该族目前世界已知2属911种。文中对该族的分类研究简史和生物学特性作了简要概述,并对种类的地理分布作了统计分析。     

Conservation of repetitive DNA sequences in deer species studied by Southern blot transfer

Summary The Cervidae show one of the largest variations in chromosome number found within a mammalian family. The five species of the deer family which are the subject of this study vary in chromosome number from 2n=70 to 2n=6. Digestion with the restriction enzymes EcoRI, HpaII, HaeIII and MspI reveals that there is a series of highly repetitive sequences forming similar band patterns in the different species. To obtain information on the degree of homology among these conserved sequences we isolated a HpaII restriction fragment of approximately 990 base pairs from reindeer DNA. This DNA sequence was³²P-labelled and hybridized by the Southern blot technique to DNAs cleaved with HpaII and HaeIII from the reindeer and four other Cervidae species. Hybridization to specific restriction fragments was recorded in all species. The patterns of hybridization showed a higher degree of similarity between reindeer, elk and roe deer than between reindeer and the Asiatic species (fallow deer and muntjac). Homologies are still present between the highly repetitive sequences of the five species despite the drastic reorganization that led to a change in chromosome number from 6 to 70.     

Detection of papillomavirus DNA in human prostatic tissue by Southern blot analysis.

Human papillomavirus deoxyribonucleic acid was detected in prostate tissue from patients with benign prostatic hyperplasia or prostatic carcinoma. Radiolabelled genomic probes, specific for the sexually transmitted human papillomavirus types 16 and 18, were used to detect viral genomic sequences in prostate DNA samples analyzed by the Southern blot technique. Viral sequences were identified in DNA from 7 of 16 prostate samples including both hyperplastic and carcinoma tissues and including tissues obtained by transurethral resection or suprapubic prostatectomy. These data indicate that the prostate gland can be infected with human papillomavirus and imply that the prostate may act as a reservoir for the sexual transmission of papillomavirus via seminal fluid. The detection of both episomal and integrated viral DNA sequences in prostate tissue may have important implications for the etiology of prostate disease.