Systematics of the Monodelphic Species of Trichodoridae (Nematoda: Diphtherophorina) With Descriptions of a New Genus and Four New Species

To show the relationship of the monodelphic species of Trichodoridae with the nominal taxa, the genus Monotrichodorus is redefined, with the addition of one new species. The new genus Allotrichodorus is proposed on the basis of new species found in Brazil; and one new species is described in the genus Paratrichodorus.     

Effects of pyrrol-carboxylic acid derivatives on the growth of coliphages.

Effects of 14 pyrrol-carboxylic acid derivatives and analogues (PY-compounds) on the growth of coliphage MS2 using E. coli E102 (Hfr) as the host were measured by the agar double-layer method. Enlargements of plaque size were observed with 7 PY-compounds but increase in plaque numbers was not induced. These enlargements of plaque size were specific to RNA coliphages MS2, GA and qbeta and not found with DNA coliphages delta AC and T4. Furthermore, the interaction between PY-compound PY-10 and the coliphage MS2 was dependent on the host bacterium (indicator strain). When E102 (Hfr) was used, the enlargement was marked, in the case of substrain W1895 (Hfr) it was less, while in the case of substrain W6 (F+) it was undetectable. The one-step growth of the phage MS2 and the production of intracellular phage MS2 were little affected by the PY-compound PY-10. However, the rate of one-step growth was increased in the early stage after infection. Accordingly, the enlargements of plaque size by the PY-compounds might be correlated with an increase in rate of release of phage particles.     

Immune response to human influenza virus hemagglutinin expressed in Escherichia coli

Cloned DNA fragments coding for parts of strain WSN (H1N1) influenza virus hemagglutinin (HA) were fused to a bacterial leader DNA derived from the Escherichia coli trp operon. Fusion proteins produced consisted of 190 amino acids of trpLE' protein at the amino terminus, and HA amino acids, either 1-308, 1-396, or 1-548 (complete HA), at the carboxyl terminus. These proteins were expressed at high levels (10-20% of total protein) in E. coli starved for tryptophan. A CNBr fragment (HA1-211) was derived from HA-308. Each of the proteins was purified and used for immunizing mice and rabbits. The antibody produced was shown to bind to (i) the HA fusion proteins, (ii) detergent-treated viral HA, (iii) HA, on intact virions, and (iv) the HA on the surface of cells infected with influenza virus. This shows that the HA fusion proteins expressed in bacteria can elicit antibodies that recognize at least some determinants of the native viral HA, and probably could lead to development of an anti-influenza vaccine.     

Molecular cloning of unintegrated visna viral DNA and characterization of frequent deletions in the 3' terminus

Visna viral DNA, like other retroviral DNA, exists in two circular forms in infected cells. The larger probably contains two copies of the LTR, the smaller, one copy. Recombinant DNA techniques were used to clone unintegrated circular visna viral DNA in the lambda WES . lambda B vector. Circular visna viral DNA was digested with the restriction enzyme SstI, which yields a 9.2-kb viral DNA fragment containing 90% of the viral genome colinear with the restriction map of linear viral DNA. This fragment extends from a site about 900 bp from the left (5') end of the viral DNA molecule, through the 3' region, including U3 and R sequences at its right (3') end. The recombinant clones isolated contain visna viral DNA inserts which range in size from 3.1 kb to 9.2 kb. All the clones contain the 5' region intact, but most had sustained deletions of varying lengths in the 3' terminal region of the cloned fragment.     

The uptake of the GABA agonist, [H]isoguvacine, by the isolated retina of the rabbit

Previous autoradiographic studies aimed at showing neurones using GABA as their neurotransmitter have been hampered by the fact that the substance is a ubiquitous metabolite and therefore accumulated by a large variety of cells, including glia. Consequently, GABA uptake markers without this widespread uptake are desirable, and one, [³H]isoguvacine, has shown promising results in autoradiographic experiments. Its uptake has now been further studied with quantitative radiochemical techniques.

The uptake of the drug was slow compared to GABA uptake and reached a tissue/medium ratio of about 3 after 120 min. The uptake could be inhibited by GABA, beta-alanine or ouabain, and by incubating the retinas at 0°C. The uptake kinetics were complex but suggested a high affinity uptake system (<i>Ki>_m about 10⁻⁸ M) and perhaps one or several systems with lower affinities.

The results indicate that [³H]isoguvacine and [³H]GABA are accumulated and retained by the same neurones, which most likely use GABA as their neurotransmitter.     

Activating mutations in the NH2- and COOH-terminal moieties of the Gs alpha subunit have dominant phenotypes and distinguishable kinetics of adenylyl cyclase stimulation.

The alpha subunit polypeptides of the G proteins Gs and Gi2 stimulate and inhibit adenylyl cyclase, respectively. The alpha s and alpha i2 subunits are 65% homologous in amino acid sequence but have highly conserved GDP/GTP binding domains. Previously, we mapped the functional adenylyl cyclase activation domain to a 122 amino acid region in the COOH-terminal moiety of the alpha s polypeptide (Osawa et al: Cell 63:697-706, 1990). The NH2-terminal half of the alpha s polypeptide encodes domains regulating beta gamma interactions and GDP dissociation. A series of chimeric cDNAs having different lengths of the NH2- or COOH-terminal coding sequence of alpha s substituted with the corresponding alpha i2 sequence were used to introduce multi-residue non-conserved mutations in different domains of the alpha s polypeptide. Mutation of either the amino- or carboxy-terminus results in an alpha s polypeptide which constitutively activates cAMP synthesis when expressed in Chinese hamster ovary cells. The activated alpha s polypeptides having mutations in either the NH2- or COOH-terminus demonstrate an enhanced rate of GTP gamma S activation of adenylyl cyclase. In membrane preparations from cells expressing the various alpha s mutants, COOH-terminal mutants, but not NH2-terminal alpha s mutants markedly enhance the maximal stimulation of adenylyl cyclase by GTP gamma S and fluoride ion. Neither mutation at the NH2- nor COOH-terminus had an effect on the GTPase activity of the alpha s polypeptides. Thus, mutation at NH2- and COOH-termini influence the rate of alpha s activation, but only the COOH-terminus appears to be involved in the regulation of the alpha s polypeptide activation domain that interacts with adenylyl cyclase.     

The function of tail fibers in triggering baseplate expansion of bacteriophage T4

Normal particles of bacteriophage T4 have six long tail fibers attached to a hexagonal baseplate. T4 particles having various complements of tail fibers were prepared by in vitro addition of fibers to fiberless particles, and the infectivity of the particles was determined. Particles having fewer than six fibers (partially fibered) were found to have a decreased probability of infection. Partially fibered particles having T4 fibers were completed by addition of T6 fibers, and the infectivity was determined on a host that lacked the T6 tail fiber receptor. Attachment of the additional fibers increased the infectivity even though the T6 fibers could not bind to the host cell. The infectivity of particles having mixtures of T4 and T6 fibers was determined on cells having only one type of receptor. The results indicated that particles bound by only three fibers have a low probability of infection. The effect of thermolabile baseplate mutations was also examined. Studies of partially fibered particles and particles with mixtures of fibers indicated that particles with altered baseplates have a less stringent requirement for binding of the tail fibers for infection.     

Genetic analysis of transpositions in the lac region of Escherichia coli

The lac region of Escherichia coli, carried on an F′ lacproB episome, was used as a target for the transposition of several transposable elements. Tn9 shows a preferential integration (by a factor of 50) into a region extending from the end of the Z gene through the Y gene. Throughout the remainder of the lacI, Z and Y genes one other short region, located in the middle of the I gene, is favored for integration. Within these favored regions many different integration points are evident. Inspection of the DNA sequence for the I and Y genes, and parts of the Z gene, shows a strong correlation between A + T richness and regions of preferential integration. Tn5 insertions follow a similar pattern, although with less preference; whereas Tn10 insertions (provided by T. J. Foster), also favor the Y gene and the end of Z, but are distributed among fewer integration points. Most of the Tn3 insertions into the episome are accompanied by a nearby or adjacent deletion.     

The effect of 5-Iodouracil on the growth and biosynthetic processes of bacteriophage T4td8 in the absence of light

5-Iodouracil (IUra)-substituted progeny bacteriophage T4td8 were grown under conditions such that, upon CsCl equilibrium isopycnic gradient centrifugation, progeny with density distributions about the median similar to that of unsubstituted phage are obtained. In the absence of light a monotonie relationship exists between decreasing progeny viability and increasing percent IUra substitution. IUra is equivalent to thymine as a growth factor on a molar basis, and at concentrations of IUra plus thymine above that required for maximum particle production, the percent IUra substitution in phage DNA is determined by the mole fraction of IUra in the medium. The lethal effects of 5-iodo-2'-deoxyuridine (IdUrd) and IUra are equivalent, and are not produced by a direct effect on the phage particles. At equivalent percent substitution in phage DNA the order of lethality is IUra > 5-bromouracil (BrUra) > 5-chlorouracil (ClUra). There is no interference with the transfer of thymine from host cell to progeny phage by the presence of IUra in the medium, and IUra affects neither the time of lysis nor the content of phage DNA in the infected cells.     

Non-random intrachromosomal distribution of chromatid aberrations induced by X-rays,alkylating agents and ethanol in Vicia faba

A reconstructed karyotype of Vicia faba with all chromosomes individually distinguishable was treated with triethylene melamine (TEM), cytostasan (CYT) (a new benzimidazol nitrogen mustard), mitomycin C (MI), ethanol (EA) and X-rays. The distribution within chromosomes of induced chromatid abberations was non-random for all agents. The number of segments involved in aberration clustering corresponded to the number of sites representing constitutive heterochromatin, or the regions immediately adjacent to these, as evidenced by the position of Giemsa marker bands. Which of these potential regions of aberration clustering reacted with preferential involvement in aberrations was, in part at least, dependent upon the inducing agent used. It is argued that this may be due to differences in the base composition and/or molecular conformation of heterochromatic regions. Unexpectedly, the distribution pattern of chromatid aberrations induced by mitomycin C was found to be different from those after treatment with the alkylating agents TEM and cytostasan although mitomycin C is assumed to induce aberrations via alkylation. If mitomycin C-induced aberrations are indeed due to alkylation, this indicates that different alkylating agents do not necessarily result in identical patterns of abberation clustering. The other two alkylating agents and ethanol resulted in similar patterns of preferential distribution of abberations. X-Ray induced chromatid aberrations also showed a non-random intrachromosomal distribution, but the clustering was less pronounced than after treatment with the chemical agents.