A variable minisatellite sequence in the chloroplast genome of Sorbus L. (Rosaceae: Maloideae).

The chloroplast genome is now known to be more variable than was once thought. Reports of RFLP (restriction fragment length polymorphism) and sequence variation, as well as variation in chloroplast microsatellites, are common. Here, data are presented on the variability of a minisatellite sequence in the chloroplast genome of Sorbus species. RFLP analysis of a PCR product comprising the region between the trnM and rbcL genes of nine Sorbus species identified seven size variants. Sequencing revealed the observed size polymorphism to be due to differences in the number of copies of an imperfect 9-bp motif. A more intensive survey of the variability of the minisatellite was undertaken in populations of Sorbus aucuparia. The potential uses of such regions in chloroplast DNA are discussed and a possible mechanism for the evolution of the minisatellite is presented.     

First descriptions of Coelometopini pupae (Coleoptera: Tenebrionidae) from Australia,Southeast Asia and the Pacific region,with comments on phylogenetic relationships and antipredator adaptations

Abstract. The pupal stage of ten Coelometopini species occurring in Australia, New Guinea, Southeast Asia and the Pacific region are described and a key for their identification is provided. The species are Chrysopeplus expolitus Broun, Derosphaerus hirtipes Kaszab, Hypaulax crenata (Boisduval), Leprocaulus borneensis Kaszab, Metisopus purpureipennis Bates, Promethis carteri Kaszab, P. nigra (Blessig), P. quadraticollis (Gebien), P. quadricollis Pascoe and P. sulcigera (Boisduval). The gin trap structures of D. hirtipes and P. quadraticollis are described in detail using scanning electron micrographs. A summary of antipredator structures of all known Coelometopini pupae is given. The phylogenetic value of pupal characters is assessed at intra‐ and intergeneric levels within the tribe.     

Restriction fragment length polymorphism at the HLA-C locus

We have used the HLA-C-specific DNA probe pC250 to investigate restriction fragment length polymorphism (RFLP) at the HLA-C locus. Genomic Southern blot hybridization included DNA prepared from a panel of homozygous typing cells representing serological specificities Cw1 to Cw8 and also from samples representing Cw blanks. Although many restriction nucleases failed to reveal any polymorphism, RFLPs were evident with Taq I, Pvu II, Bst XI, Nde 1, and Nci I in addition to the previously reported Eco RI. In the case of Bst XI, a unique RFLP defined a subset of serologically defined Cw blanks. Comparison of RFLP sizes with restriction fragment lengths obtained from the known HLA-Cw3 gene sequence permitted the localization of intragenic C locus RFLLs and the identification of a variable Taq I site in the second intron, a variable Nci I site near the end of the fourth exon, and a variable Pvu lI site in the fifth intron.     

Development of High-Frequency Delivery System for Transposon Tn919 in Lactic Streptococci: Random Insertion in Streptococcus lactis subsp. diacetylactis 18-16

The conjugative transposon Tn919, originally isolated in Streptococcus sanguis FC1, is capable of low-frequency transfer (10⁻⁷ and 10⁻⁸ per recipient) on membrane filters to a wide number of streptococcal recipients including the industrially important lactic streptococci. The introduction of pMG600 (Lac⁺ Lax⁻; a lactose plasmid capable of conjugative transfer at high frequencies and which, in certain hosts, confers an unusual clumping phenotype) into a Streptococcus lactis CH919 donor, generating S. lactis CH001, resulted in a significant improvement in the transfer frequency of Tn919 to S. lactis CK50 (1.25 × 10⁻⁴ per recipient). In addition, these matings could be performed on agar surfaces, allowing the recovery of a greater number of recipients than with filter matings. Tn919 also transferred at high frequency to S. lactis subsp. diacetylactis 18-16S but not to Streptococcus cremoris strains. Insertion in 18-16S transconjugants generated from filter matings with an S. lactis CH919 donor was random, occurring at different sites on the chromosome and also in plasmid DNA. Thus, the conditions necessary for the practical exploitation of Tn919 in the targeting and cloning of genes from a member of the lactic streptococci, namely, high-frequency delivery and random insertion in host DNA, were achieved.     

Characterization of Merkel cells and mechanosensory axons of the rat by styryl pyridinium dyes

Summary The epidermal Merkel cells and their sensory innervation serve tactile sensation in vertebrates. In this study the fluorescent cationic mitochondrial dye, 4-(4-diethylaminostyryl)-N-methylpyridinium iodide (4-Di-2-ASP), which has recently been used as a vital stain for motor and autonomic nerve terminals, was tested for its ability to stain Merkel cells and sensory fibers in the snout of the rat. Brightly-fluorescent structures resembling Merkel cells as well as nerve fibers and their terminations were evident in whole mounts of the vibrissal follicle. Unilateral denervation of the vibrissal follicles soon after birth resulted in a staining pattern remarkably similar to that obtained after labelling of the Merkel cells selectively with the fluorescent marker quinacrine, but all fiber staining was abolished. Likewise, in the separated epidermis of other skin regions, including the hairy and glabrous skin of the nose, the staining pattern revealed by 4-Di-2-ASP was indistinguishable from that obtained by quinacrine fluorescence. These results indicate that certain styryl pyridinium dyes may be used as vital stains for epidermal Merkel cells as well as cutaneous mechanosensory axons.     

Molecular analysis of methane monooxygenase from Methylococcus capsulatus (Bath)

Methane monooxygenase (MMO) is the enzyme responsible for the conversion of methane to methanol in methanotrophic bacteria. In addition, this enzyme complex oxidizes a wide range of aliphatic and aromatic compounds in a number of potentially useful biotransformations. In this study, we have used biochemical data obtained from purification and characterization of the soluble MMO from Methylococcus capsulatus (Bath), to identify structural genes encoding this enzyme by oligonucleotide probing. The genes encoding the and subunits of MMO were found to be chromosomally located and were linked in this organism. We report here on the analysis of a recombinant plasmid containing 12 kilobases of Methylococcus DNA and provide the first evidence for the localization and linkage of genes encoding the methane monooxygenase enzyme complex. DNA sequence analysis suggests that the primary structures of the and subunit of MMO are completely novel and the complete sequence of these genes is presented.     

Demonstration of LH inhibitor(s) in sheep and human sera

In mature rat Leydig cells, the testosterone output (24 ng/10(6) Leydig cells/4hrs.) is increased 10 fold by LH; the addition of serum from either control or castrated or hypophysectomized rams inhibits (60%) the LH-stimulated testosterone production. Similarly, the incubation of immature rat Leydig cells with sera from hypophysectomized patients leads to a diminution (70 and 30% respectively) of both basal (0.98 ng) and LH stimulated (3.44 ng) testosterone biosynthesis. These data suggest the existence of an LH inhibitor (or inhibitors) in blood from ram and human; in addition, this substance is not only of testicular origin and is not an LH-related molecule.     

Chemical modification of the actin binding site of rabbit muscle aldolase by diethylpyrocarbonate

Summary To extend the available information on the significance of the interactions between glycolytic enzymes and the actin component of the cellular ultrastructure, investigations into the compositional characteristics of the actin binding site on one of the major glycolytic enzymes, aldolase, have been undertaken. As the electrostatic nature of the association has been previously reported indicative of a cationic region on the enzyme involved in the binding, these studies have investigated the possibility of the involvement of histidine residues in this binding region. By the use of the histidine specific reagent, diethylpyrocarbonate, we have been able to establish a difference in nature of an actin binding domain and the active site domain which does contain an essential histidine. The results have been discussed in relation to the significance of this finding with respect to the binding of aldolase to subcellular structure.     

Simultaneous utilization of glucose and xylose byCandida curvata D in continuous culture

Summary Of ten, mainly oleaginous, yeasts examined for the ability to use glucose and xylose simultaneously, only one,Candida curvata D, was found which could do so. This yeast was examined further in a single-stage chemostat wherein it produced similar biomass yields, lipid contents and fatty acids on glucose plus xylose mixed in varying proportions. This oleaginous yeast would therefore be capable of growing on hydrolysed wood and straw wastes as a potential source of single cell oil.