Replication in Drosophila chromosomes

DNA fibre autoradiography of highly polytenized nuclei in salivary glands of Drosophila nasuta larvae reveals two distinct types of active replicons. Type I replicons are longer (mean size=64 m), have a very high rate of fork migration (average rate=0.95 m/min) and generally occur in large arrays often extending over several thousand m. In contrast, the type II replicons are smaller (mean size= 20 m), slow replicating (average rate=0.07 m/min) and occur in short arrays containing only a few closely spaced active replicons. Evidence is presented that type I replicons are active in the early S and type II in the late S. Observations on autoradiographic labelling of partially lysed polytene chromosomes provide evidence for a lack of temporal and spatial agreement in the activation of origin points in homologous regions of the lateral polytene strands; these observations also suggest local variations in levels of polyteny within a chromosome. On the basis of this and other available information on replication in polytene chromosomes the possible roles of the two replicon types in the generation of the different ³H-thymidine labelling patterns of polytene chromosomes are discussed.We take pleasure in dedicating this paper to our inspiring teacher Prof. S.P. Ray Chaudhuri on his completing 75 years of fruitful life     

Acriflavin-HNO2 fluorochroming and highly repetitive DNA in polytene chromosomes

A differential staining pattern is described for polytene chromosomes from Rhynchosciara angelae larvae, stained with acriflavin-HNO₂ after alkali treatment. — Many of the bright fluorescent bands observed after staining share in common heterochromatic properties and contain repetitive DNA sequences from the fast and intermediate reassociating fractions of salivary gland DNA.     

The effects of aluminium on nodulation and symbiotic nitrogen fixation in Casuarina cunninghamiana Miq.

In order to investigate the effects of Al on nodule formation and function in the Casuarina-Frankia symbiosis, inoculated plants were grown in sand culture at five nominal Al concentrations (0-880 M Al) at pH 4.0. There was an Al-free control at pH 6.0 to assess the effects of pH 4.0 treatments. Mean N concentration of nodules was significantly less at pH 4.0 (1.83%) than at pH 6.0 (2.01%). There were nodulated plants at all Al levels, though there were fewer nodulated plants at 440 and 880 M Al. Dry weights of nodules, shoots and roots were not reduced by Al concentrations at or below 220 M Al, but were decreased by Al concentrations at or above 440 M Al. Nodule weight expressed as a percentage of total weight did not differ significantly with respect to an Al-free control at pH 4. N concentrations of shoots and whole plants were significantly reduced at 440 M Al. Nodular specific acetylene reduction activity (ARA) did not differ significantly among Al treatments. However, N₂-fixation efficiency was decreased from 0.20 to 0.10 mg N fixed mg nodule dry weight^–1 at 880 M Al.     

Steroid Polyols from the Far Eastern Starfish Henricia sanguinolenta and H. leviuscula leviuscula

Two new asterosaponins, (20R)-3-O--D-(2-O-methylxylopyranosyl)-24-propylcholest-4-ene-3,6,8,15,16,29-hexaol (sanguinoside A) and (20R,24S)-3-O--D-(2,3,4-tri-O-methylxylopyranosyl)-5-cholestane-3,4,6,8,15,24-hexaol (sanguinoside B), were isolated from two species of Pacific Far Eastern Starfish Henricia sanguinolenta and H. leviuscula leviuscula, collected in the Sea of Okhotsk. Both glycosides contain aglycones with pentahydroxysteroid nuclei of similar structures, which are substituted at the 3-hydroxy group with differently methylated -D-xylosyl residues. Sanguinoside A has an unusual structure of its aglycone side chain, whereas sanguinoside B has a unique permethylated carbohydrate chain. In addition, laevisculoside G, a known glycoside, was identified in the H. leviuscula starfish. The structures of the isolated glycosides were established by interpreting their spectral data and by comparing their spectral characteristics with those of known compounds.     

Cytological and morphological studies of the action of lithium on the development of the sea urchin embryo

Summary The effect of lithium ions on cleavage and development of sea urchin larvae was investigated. Lithium was found to interfere with the movements of the chromosomes at mitosis, which is also very delayed in the presence of lithium. The disturbances inflicted by lithium were observed during the course of development up to the pluteus stage.The lithium sensitive period coincides with the period in which the mitotic activity reaches its maximum.The rate of cleavage is reduced by lithium. In the normal untreated larva there is during the early blastula stage an animal trend in which the formation of cells of prospective ectodermal significance preponderates. The mesomeres were found to be relatively more affected by lithium than were the macromeres. This shift in the cleavage pattern influences the numbers of cells of ectodermal and endo-mesodermal significance.Studies were also made of morphological changes following treatment with lithium.     

Comparative residual toxicities of pesticides to the predator Agistemus industani (Acari: Stigmaeidae) on citrus in Florida

Residual toxicities of registered and selected experimental pesticides used on citrus against Agistemus industani Gonzalez (Acari: Stigmaeidae) were compared. Pesticides considered highly toxic to A. industani were: abamectin 0.15 EC at 731ml/ha+FC 435-66 petroleum oil at 46.8l/ha, pyridaben 75WP at 469g/ha, ethion 4EC at 7.01l/ha+FC 435-66 petroleum oil at 46.8l/ha, propargite 6.55 EC at 3.51l/ha, chlorfenapyr 2SC at 1.46l/ha applied alone or in combination with FC 435-66 petroleum oil at 46.8l/ha, sulphur 80DF at 16.81kg/ha, dicofol 4EC at 7.01l/ha, fenbutatin oxide 50WP at 2.24kg/ha, benomyl 50WP at 2.24kg/ha, benomyl 50WP at 1.68kg/ha+ferbam 76 GF at 5.60kg/ha, ferbam 76GF at 11.21kg/ha, neem oil 90EC at 46.8l/ha, and copper hydroxide DF (40% metallic copper) at 4.48kg metallic copper/ha+FC 435-66 petroleum oil at 46.8l/ha. Pesticides that were moderately to slightly toxic included: copper sulphate 98% at 4.48kg metallic copper/ha+FC 435-66 petroleum oil at 46.8l/ha, fenbuconazole 2F at 280ml/ha+FC 435-66 petroleum oil at 46.8l/ha, FC 435-66 petroleum oil applied alone at 46.8l/ha or 23.4l/ha, and diflubenzuron 25WP at 1.40kg/ha. Pesticides that were non-toxic included: fenbuconazole 2F at 585ml/ha, malathion 57EC at 5.85l/ha, FC 435-66 petroleum oil at 46.8l/ha, carbaryl 80S at 3.36kg/ha, chlorpyrifos 4EC at 4.68l/ha, and formetanate 92SP at 1.12kg/ha. Understanding the toxic effects of field weathered pesticides against key predacious mite species is important for effective IPM. The results of this study provide a comparison of direct and indirect toxic effects of various pesticides to A. industani under field conditions.     

Acclimation of the Sea Cucumber Apostichopus japonicus to Decreased Salinity at the Blastula and Gastrula Stages: Its Effect on the Desalination Resistance of Larvae at Subsequent Stages of Development

Apostichopus (= Stichopus) japonicus blastulae and gastrulae were acclimated for 18 h to salinities of 32 (control), 24 and 22 (the lower limit of the range of tolerance), and 20 (below the range of tolerance). Acclimation to 20 resulted in the appearance of teratic larvae, most of which subsequently died. Acclimation to 24, 22, and 20 led to a shift in the range of tolerance of the larvae at further stages of development. With a decrease in salinity, acclimated larvae developed more successfully than unacclimated larvae. Acclimated larvae attained the pentactula stage and settled at a salinity range of 32–20; unacclimated larvae, at 32–22. At different stages of development, acclimated larvae survived greater decreases in salinity than unacclimated larvae. The acclimation effects could be traced up to metamorphosis and settling, i.e., two weeks after the end of the acclimation process.     

Binding of the galactose-specificPseudomonas aeruginosa lectin,PA-I,to glycosphingolipids and other glycoconjugates

The carbohydrate-binding specificity ofPseudomonas aeruginosa lectin I (PA-I) in iodinated or biotinylated form was studied. A large number of glycosphingolipids, as well as some glycoproteins and neoglycoproteins were used as ligands. Also, inhibition by free saccharides of PA-I binding to glycosphingolipids was tested. It was found that the lectin binds most strongly to terminal and nonsubstituted Gal3Gal- or Gal4Gal-structures.Abbreviations PA-I Pseudomonas aeruginosa lectin I - Cer ceramide - lactosylceramide Gal4GlcCer - iso globotriaosylcerami Gal3Gal4GlcCer - globotriaosylceramide Gal4Gal4GlcCer - globoside or globotetraosylceramide GalNAc3Gal4Gal4GlcCer - Forssman glycolipid GalNAc3GalNAc3Gal4Gal4GlcCer - P1 glycolipid Gal4Gal4GlcNAc3Gal4GlcCer - lactoneotetraosylceramide Gal4GlcNAc3Gal4GlcCer - B5 glycolipid Gal3Gal4GlcNAc3Gal4GlcCer - gangliotetraosylceramide Gal3GalNAc4Gal4GlcCer - GM1 Gal3GalNAc4(NeuAc3)Gal4GlcCer - RBC red blood cells - BSA bovine serum albumin - PBS phosphate-buffered saline - SDS sodium dodecyl sulfate - TLC thin-layer chromatography - HPLC high pressure liquid chromatography - MS mass spectrometry - FAB fast-atom bombardment - EI electron impact     

Multiple forms of inducible drug-metabolizing enzymes: A reasonable mechanism by which any organism can cope with adversity

Summary All organisms possess a number of genetically regulated mechanisms in order to cope with rapid adverse changes in the environment. The two systems which appear to respond to a seemingly endless array of chemical specificities are the immune response and the induction of drug-metabolizing enzymes. Similarities and differences between the immunoglobulin and the cytochrome P-450-mediated monooxygenase systems are described. DNA insertion sequences, plasmid transposons, maize controlling elements, gene duplication, intervening sequences, and high-frequency intergenic recombination are all discussed as possible methods by which organisms can adapt quickly to a new selective pressure. If the regulation of P-450 induction resembles in any way the other methods by which pro- and eukaryotes cope genetically with numerous forms of environmental adversity, therefore, it is very likely that mammalian tissues contain hundreds, if not thousands, of inducible forms of P-450.Portions of this overview were presented at the Symposium on The Effects of Drugs on Enzyme Induction Related to the Metabolism of Drugs and Carcinogenic Compounds, 14th Symposium Medicum Hoechst, County Mayo, Ireland, May, 1978 (1), and the Symposium on Isolated Drug-Metabolizing Enzymes, Mainz, Germany, July, 1978 (2). The author is Chief of the Developmental Pharmacology Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20205.     

Effect of α-amanitine on puffing and intranuclear RNA synthesis in Chironomus salivary glands

Incubation of Chironomus salivary glands with -amanitine in concentrations from 1 to 10 /ml results in the suppression of puffing and chromosomal ³H-uridine incorporation after 30 to 60 min in 80% of the cells. Nucleolar ³H-uridine incorporation remains completely unaffected. Even 4 h after the injection of high doses of -amanitine into living larvae, nucleolar incorporation is still pronounced. The distribution of resistant cells within the salivary glands suggests that the uptake of -amanitine is subject to physiological restrictions.—A puff typically induced during in vitro incubation of salivary glands was found to be less sensitive to -amanitine than the Balbiani rings.     

Transposition of mobile genetic elements in interspecific hybrids of Drosophila

In situ hybridization of labeled DNA of four mobile dispersed genetic elements (mdg), isolated from D. melanogaster and C. virilis genomes, with polytene chromosomes of the larvae of several Drosophila species has been carried out. The data show that the mdg elements exhibit a high degree of species specificity. The same conclusions are derived from filter hybridization using ³²P-labeled D. melanogaster and D. virilis DNA and cloned mdg sequences immobilized on nitrocellulose filters. We attempted to induce transpositions (jumping) of mdg elements specific for D. virilis chromosomes to the chromosomes of related species (e.g. D. littoralis Meigen) originally lacking the representatives of this family of repeats. For this purpose we produced hybrid stocks with synthetic karyotoypes characterized by different combinations of D. virilis homologous chromosomes and hybrid chromosomes. In one of such stocks we did find by in situ hybridization the insertion of a D. virilis mdg element into the fifth chromosome of D. littoralis Meigen. The transposition (jumping) took place in the only region where somatic pairing between the fifth chromosomes of D. virilis and D. littoralis occurs more or less regularly in the hybrids. Since crossing-over in hybrid chromosomes of males is excluded in such synthetic stocks, gene conversion may be responsible for this transposition. The possible bearing of the phenomenon observed on the problem of hybrid dysgenesis is discussed.     

Action of rat liver Galβ1-4GlcNAc α(2-6)-sialyltransferase on Manβ1-4GlcNAcβ-OMe,GalNAcβ1-4GlcNAcβ-OMe,Glcβ1-4GlcNAcβ-OMe and GlcNAcβ1-4GlcNAcβ-OMe as synthetic substrates

Incubation of synthetic Man\1-4GlcNAc-OMe, GalNAc1-4GlcNAc-OMe, Glc1-4GlcNAc-OMe, and GlcNAc1-4GlcNac-OMe with CMP-Neu5Ac and rat liver Gal1-4GlcNAc (2-6)-sialyltransferase resulted in the formation of Neu5Ac2-6Man1-4GlcNAc-OMe, Neu5Ac2-6GalNAc1-4GlcNAc-OMe, Neu5Ac2-6Glc1-4GlcNAc-OMe and Neu5Ac2-6GlcNAc1-4GlcNAc-OMe, respectively. Under conditions which led to quantitative conversion of Gal1-4GlcNAc-OEt into Neu5Ac2-6Gal1-4GlcNAc-OEt, the aforementioned products were obtained in yields of 4%, 48%, 16% and 8%, respectively. HPLC on Partisil 10 SAX was used to isolate the various sialyltrisaccharides, and identification was carried out using 1- and 2-dimensional 500-MHz¹H-NMR spectroscopy.Abbreviations 2D 2-dimensional - CMP cytidine 5-monophosphate - CMP-Neu5Ac cytidine 5-monophospho--N-acetylneuraminic acid - COSY correlation spectroscopy - DQF double quantum filtered - HOHAHA homonuclear Hartmann-Hahn - MLEV composite pulse devised by M. Levitt - Neu5Ac N-acetylneuraminic acid - Neu5Ac2en 2-deoxy-2,3-didehydro-N-acetylneuraminic acid     

Conformational energy analysis of the leucine repeat regions of C/EBP, GCN4, and the proteins of the myc, jun, and fos oncogenes

It has been recently proposed that certain DNA binding proteins (including C/EBP, GCN4 and themyc, jun, andfos oncogene proteins) share a common structural motif based on helix-promoting regions containing heptad repeat sequences of leucines. It has been suggested that this structure is critical to the biological activity of these proteins, since it facilitates the formation of functional dimers held together by interdigitating leucine side-chains along the hydrophobic interfaces between long -helical regions of the polypeptide chains in a configuration termed the leucine zipper. In this paper, conformational energy analysis is used to determine the preferred three-dimensional structures of the leucine repeat regions of these proteins. The results indicate that, in all cases, the global minimum energy conformation for these regions is an amphipathic -helix with the leucine side-chains arrayed on one side in such a way to favor leucine zipper dimerization. Furthermore, amino acid substitutions in these regions (such as Pro for Leu), that are known to inhibit dimer formation and prevent DNA binding, are found to produce significant conformational changes that disrupt the amphipathic helical structure. Thus, these results provide support for the proposed leucine zipper configuration as a critical structural feature of this class of DNA binding proteins.     

Effect of androgens on histochemical fibre type

Summary The temporal muscles of the guinea pig show a sexual differentiation reflected in their histochemical enzyme pattern. Using histochemical methods for mitochondrial (SDH, -GPDH), and glycolytic enzymes (phosphorylase, LDH) it could be shown, that in adult animals the male muscle is a white muscle with marked activity of glycolytic enzymes, the female muscle a red muscle displaying high activity of mitochondrial enzymes. This differential enzyme pattern can be converted by the application of testosterone to the female type during the postnatal development. The male sex hormone thus affects the histochemical enzyme pattern of the muscle, converting the red, female into a white, male muscle in the female guinea pig.     

Expression of a chimeric stilbene synthase gene in transgenic wheat lines

A chimeric stilbene synthase (sts)gene was transferred into wheat. Stilbene synthases play a role in the defence against fungal diseases in some plant species (e.g. groundnut or grapevine) by producing stilbenetype phytoalexins like resveratrol. Resveratrol is also claimed to have positive effects to human health. Embryogenic scutellar calli derived from immature embryos of the two commercial German spring wheat cultivars Combi and Hanno were used as target tissue for cotransformation by microprojectile delivery. The selectable marker/reporter gene constructs contained the bargene either driven by the ubiquitinpromoter from maize (pAHC 25, also containing the uidAgene driven by the ubiquitinpromoter), or by the actinpromoter (pDM 302) from rice. The cotransferred plasmid pStil 2 consisted of a grapevine stscoding region driven by the ubiquitin promoter. Eight transgenic Combi and one Hanno T_Oplant were obtained and, except one Combi T_Oplant, found to be cotransformants due to the integration of both the stsgene and the selectable marker or reporter genes. Expression of the stsgene was proven by RTPCR, and, for the first time, by detection of the stilbene synthase product resveratrol by HPLC and mass spectrometry. The stsgene was expressed in four of the seven transgenic Combi T_{_o}plants. Two of the respective T₁progenies segregated in a Mendelian manner were still expressing the gene. Investigations into methylation of the stsgene showed that in three nonexpressing progenies inactivation was paralleled by methylation.     

Chromatin elimination in the hypotrichous ciliate Stylonychia mytilus

Chromatin elimination in the hypotrichous ciliate Stylonychia mytilus was studied by means of electron microscopy using a microspreading procedure. In the polytene chromosomes of the macronuclear anlagen three organization patterns are observed: Bands of various size composed of 300 Å chromatin fibers, large blocks of 300 Å nucleofilaments which probably represent the heterochromatic regions of the chromosome and axial 120 Å filaments. Those DNA sequences which become eliminated belong to the 300 Å fiber type. The eliminated chromatin occurs in the form of rings of variable size corresponding to a DNA content between 18 and 160 Kb while the axial 120 Å filaments appear to be preserved.     

Effect of propranolol on cardiac cytokine expression after myocardial infarction in rats

The pro-inflammatory cytokines interleukin (IL)-1 and IL-6 have been shown to be upregulated in the myocardium after injury and after adrenergic receptor stimulation. Together with other cytokines, such as the transforming growth factor (TGF)-, the pro-inflammatory cytokines have been implicated in the initiation of tissue repair and wound healing after myocardial infarction (MI). In the present study, the effect of -adrenergic receptor blockade with propranolol (2 mg/kg·h s.c. by miniosmotic pumps) on cardiac cytokine expression and on wound healing was analyzed in rats from 6–72 h after MI. IL-1 and IL-6 gene expression strongly increased in the infarcted myocardium 6 h after MI and peaked after 12 h, while TGF-, progressively increased from 12 h onwards. Also, TGF-₂ increased after 12 h, peaked after 24 h and declined thereafter, while TGF-, was only elevated after 72 h. Treatment with propranolol had a negative chronotropic effect throughout the observation period of 72 h. It attenuated the initial elevation in LVEDP and increased cardiac output ultimately. Furthermore, propranolol attenuated IL-1 mRNA expression, but had not effect on the other cytokines. Moreover, MMP-9 gelatinolytic activity was markedly attenuated by propranolol indicating a delayed resorption of the necrotic tissue and, possibly, collagen turnover. Replacement by scar tissue, however, was not affected as indicated by normal collagen expression.     

Studies on aneuploids of Petunia

Summary The seven possible primary trisomics of Petunia (2 n= 14) located in the progenies of triploid, hypertriploid and hypotriploid plants were distinguished from one another and from diploid on the basis of cytological and morphological criteria. They were provisionally named as Oval, Semi, Slender, Pseudonormal, Arrow, Narrow and Giant. In three of the trisomics, the extra chromosome was identified for the first time at pachytene stage. Postpachytene studies revealed no precise relationship between the length of extra chromosome and the frequency of multiple association.     

Genetic linkage between endosperm storage protein genes on each of the short arms of chromosomes 1A and 1B in wheat

Summary The storage proteins of the endosperm of wheat grain which are known to be controlled by genes on the short arms of the homoeologous group 1 chromosomes are (1) the -gliadins, (2) most of the -gliadins, (3) a few -gliadins and (4) the major lowmolecular-weight subunits of glutenin. Several crosses were made between varieties or genetic lines which had contrasting allelic variants for some of these proteins and which were coded by genes on chromosomes 1A or 1B. The progeny were analysed by one or more of several electrophoretic procedures. The results of all the analyses are consistent with the hypothesis that chromosomes 1A and 1B each contain just one, complex locus, named Gli-A 1 and Gli-B 1 respectively, which contain the genes for the -, - and -gliadins and the low-molecular-weight subunits of glutenin.     

Immunization of cross-bred cattle against Hyalomma anatolicum anatolicum by purified antigens

Extracts prepared from unfed larvae of Hyalomma anatolicum anatolicum were purified by immunoaffinity chromatography using anti-gut IgG as ligand. Affinity purified antigen (Aff-GHLAg) was used to immunize cross-bred (Bos taurus×B. indicus) calves of 6–7 months of age. Immunized calves rejected 70.6% larvae, 54.5% nymphs and 61.9% adults. No significant changes in the engorged weight of females was observed; however, significant decrease in the engorgement weight of larvae and nymphs was recorded. There was a significant decrease in the emerging nymphs (p<0.05) and adults (p<0.01) of the tick stages fed on immunized animals. SDS-PAGE analysis revealed three antigenic proteins of 100, 59.4 and 37kDa responsible for induction of resistance in the host.