Analysis of acidic and basic chitinases from tobacco and petunia and their constitutive expression in transgenic tobacco

cDNA clones of messenger RNAs for acidic and basic chitinases were isolated from libraries of tobacco mosaic virus-infected Samsun NN tobacco and petunia. The tobacco cDNA clones for acidic chitinase fell into two different groups, whereas all petunia cDNA clones had the same sequence. Also, tobacco genomic clones were isolated and one was characterized. This genomic clone, corresponding to one of the cDNA clones, showed that this acidic chitinase gene contains two introns. The amino acid sequences of the acidic chitinases from tobacco, as deduced from the cDNA clones, fully agreed with partial sequences derived from peptides obtained from purified tobacco-derived pathogenesis-related proteins PR-P and PR-Q. The deduced amino acid sequences showed that PR-P and PR-Q are 93 and 78%, respectively, identical to the petunia enzyme. All deduced chitinase sequences indicated the presence of an NH2-terminal, highly hydrophobic signal peptide. In addition, the polysaccharide-binding domain present at the NH2-terminus of basic chitinases from mature tobacco is not present in these acidic chitinases. Furthermore, the complete coding sequence for the petunia chitinase, constructed downstream of the cauliflower mosaic virus 35S promoter, was used to transform tobacco. The resulting chimeric gene was constitutively expressed, and the petunia enzyme was targeted to the extracellular fluid. In contrast, a basic chitinase of tobacco, expressed from a chimeric gene, was found in total leaf extracts but not in preparations of extracellular fluid.     

Morphology and Taxonomy of <Emphasis Type="Italic">Apristurus longicephahis</Emphasis> (Lamniformes,Seyliorhinidae)

Data on the individual variation and changes with growth in proportions and morphology are presented for the poorly known Apristurus longicephalus, and compared with those of other species. A. longicephalus is concluded to be a distinct species without synonyms, characterized by its long snout, widely separate nostrils, long caudal fin, short abdomen, very sparse teeth, and low number of monospondylous vertebrae. It is a species of small size, maturing at about 42 cm in total length.     

Scale Growth and Squamation Chronology for the Laboratory-Reared Hermaphroditic Fish <Emphasis Type="Italic">Rivulus marmoratus</Emphasis> (Cyprinodontidae)

Scale morphology, growth and the squarnation chronology are described for the hermaphroditic fish Rivulus marmoratus reared in the laboratory. The scales are round or oval shaped cycloid type, and their sizes are about 0.3–1.0 mm in diameter. The number of ridges increases more rapidly relative to the body growth of the fish in early stages, but this increase is proportionate to growth subsequently. Three loci of scale development have been identified. The scales first appeared on the center of the parietal region at 8 days after hatching. The second locus of scale formation was on the lateral line of the posterior end of the caudal peduncle. A third locus was later observed on the lower right corner of the operculum: The final squamation was completed at 6 weeks after hatching.     

Cultural characteristics and zearalenone production by strains of<Emphasis Type="Underline">Fusarium</Emphasis> from wheat

Conidia of the speciesFusarium culmorum /W.G.Sm./ Sacc. andFusarium graminearum Schwabe are characterized by variability in zearalenone production and dimensions depending on the substrate. The sporulation of isolates from some wheat eultivars have been deprived in vivo and in vitro in the first passage, but not their pathogenicity and toxic metabolites production. Nonsporulating strains produced lower quantités of zearalenone than sporulating ones. Liquid filtrates of such nonsporulating strains had a high phytotoxic effect on wheat caryopses. The crystalline toxin DAS /0,25 ug/ml/ had low phytotoxic effect on wheat caryopses.     

Cumulation of mycotoxins in maize cobs infected with<Emphasis Type="Italic">Fusarium gramihearum</Emphasis>

Maize cobs withFusarium ear rot were collected at 1986 season and five infected byFusarium graminearum were analyzed for presence of triohothecenes and zearalenone. Collected material was subsampled forFusarium damaged kernels and corresponding axial stems and healthy looking kernels. All investigated cobs contained deoxynivalenol (DON) (range 18.0–131.5 mg/kg) and zearalenone (ZEA) (range 0.38–2.17 mg/kg), in four cobs 15-acetyl-deoxynivalenol (15-AcDON) (range 5.2–6.2 mg/kg) was present and two cobs besides three all metabolites contained 3-acetyl-deoxynivalenol (3-AcD0N) (range 0.5–0.8 mg/kg).The average of individual toxins amount in axial stems: in mg/kg was equal to: DON — 110.36, ZEA — 4.57, 15-AcD0N — 16.66, and 3-AcD0N — 1.32.Fusarium damaged kernels contained in average the following amount (mg/kg) of: DON 77.00, ZEA 0.98, 15-AcD0N 3.78 and 3-AcD0N 0.06. Healthy looking kernels contained DON 1.96 mg/kg and ZEA 0.07 mg/kg only. Cooccurrence of 3-AcDON and 15-AcDON in two samples was an interesting finding. The amount of DON in total cob was highly correlated (r = 0.94) with percentage ofFusarium damaged kernels in given ear.     

Ultrastructural colocalization of tyrosinated and detyrosinated alpha-tubulin in interphase and mitotic cells

Immunofluorescence with specific peptide antibodies has previously established that tyrosinated (Tyr) and detyrosinated (Glu) tubulin, the two species generated by posttranslational modification of the COOH-terminus of alpha-tubulin, are present in distinct, but overlapping, subsets of microtubules in cultured cells (Gundersen, G. G., M. H. Kalnoski, and J. C. Bulinski, 1984, Cell, 38:779-789). Similar results were observed by light microscopic immunogold staining in the two cell types used in this study, CV1 and PtK2 cells: most microtubules were stained with the Tyr antibody, whereas only a few were stained with the Glu antibody. We have examined immunogold-stained preparations by electron microscopy to extend these results. In general, electron microscopic localization confirmed results obtained at the light microscopic level: the majority of the microtubules in CV1 and PtK2 cells were nearly continuously labeled with the Tyr antibody, whereas only a few were heavily labeled with the Glu antibody. However, in contrast to the light microscopic staining, we found that all microtubules of interphase and mitotic CV1 and PtK2 cells contained detectable Tyr and Glu immunoreactivity at the electron microscopic level. No specific localization of either species was observed in microtubules near particular organelles (e.g., mitochondria or intermediate filaments). Quantification of the relative levels of Glu and Tyr immunoreactivity in individual interphase and metaphase microtubules showed that all classes of spindle microtubules (i.e., kinetochore, polar, and astral) contained nearly the same level of Glu immunoreactivity; this level of Glu immunoreactivity was lower than that found in all interphase microtubules. Most interphase microtubules had low levels of Glu immunoreactivity, whereas a few had relatively high levels; the latter corresponded to morphologically sinuous microtubules. Quantification of the relative levels of Tyr and Glu immunoreactivity in segments along individual microtubules suggested that the level of Tyr (or Glu) tubulin in a given microtubule was uniform along its length. Understanding how microtubules with different levels of Tyr and Glu tubulin arise will be important for understanding the role of tyrosination/detyrosination in microtubule function. Additionally, the coexistence of microtubules with different levels of the two species may have important implications for microtubule dynamics in vivo.     

Assessment of tibial stiffness by vibration testing in situ--II. Influence of soft tissues, joints and fibula

The influence of soft tissues and joints on the vibration of the human tibia was examined by modal analysis on amputated lower limbs, where the soft tissues and the fibula were dissected gradually. Measurements were made in two different set ups, IFR and BRA, which were both designed to monitor fracture healing. In IFR, vibrations are generated by hammer impact on a relaxed hanging lower leg, with the knee flexed. Resonant frequencies are determined by a computer Fourier transform procedure. In BRA, a steady state vibration is induced in a lower leg, supported near the ankle and the tibial tuberosity, using an electromagnetic shaker. Resonant frequencies are determined from the maxima in vibration amplitudes. In both set ups the soft tissues have a similar influence on the vibration of the tibia: the skin hardly influences the determined modal parameter. The mass of the muscles influences both the resonant frequency and the damping. The fibula has a stiffening effect on the tibia. The influence of the joints is small in the IFR-set up: the tibia vibrates in conditions close to those for the free-free vibration. In the BRA-set up, the supports determine the boundary conditions.     

Mobilization of the transposable element mdg4 by hybrid dysgenesis generates a family of unstable cut mutations in Drosophila melanogaster

Summary A family of unstable mutations at the cut locus in Drosophila melanogaster was obtained under the conditions of hybrid dysgenesis (Gerasimova 1981, 1982). The in situ hybridization experiments have shown that, in the original unstable ct ^MR2 mutation, the 7B region of the X chromosome (where cut is located) contains a mobile dispersed genetic element, mdg4. All other unstable ct mutations derived from ct ^MR2 including visible and lethal alleles and unstable ct ⁺ reversions, also contain mdg4 in the 7B region. The X chromosomes of the parent strain (wild type) do not contain mdg4 at all. All stable revertants derived from ct ^MR2, from other unstable ct mutations, or from ct lethals lost mdg4 from the 7B region. The ct ^MR2 X chromosome does not contain P-elements, although a few copies are present in the autosomes. The instability of the ct ^MR2./ct ^MR2 strain remained at a high level for 50 generations (1.5 years) and then rapidly decreased. A new cross with an MRh12/Cy strain (originally used for dysgenesis induction and containing a number of P-elements) increased the instability to a level exceeding the original one. The data strongly suggest that unstable ct mutations in our system are induced by transpositions of mdg4, possibly activated by P-elements.