Changes in soil microflora associated with control of Sclerotium Rolfsii by Furfuraldehyde

The efficacy of 2‐furfuraldehyde for control of Sclerotium rolfsii was studied in laboratory and greenhouse experiments. Mycelial growth of the fungus was reduced proportionally with concentrations of 0.1–0.5 ml furfuraldehyde l^‐1 agar medium, and viability of sclerotia diminished on exposure to 2‐furfuraldehyde vapours. Detectable populations of bacteria and fungi, including Trichoderma spp., were reduced significantly (9=0.05) when furfuraldehyde was added to the agar used for soil dilution plates of untreated soil. Repeated treatments of natural soil with the fumigant significantly increased populations of Trichoderma spp. and bacteria, but diminished numbers of actinomycetes. Increasing dosages applied to soil artificially infested with S. rolfsii caused a reduction of disease on lentil, Lens culinaris. Results indicate that the compound, when applied to field soil, changes the composition of soil microflora and has potential for integrated control of S. rolfsii.     

A Comparison of the Efficacy of Nuclear Polyhedrosis and Granulosis Viruses in Spray and Bait Formulations for the Control of Agrotis segetum (Lepidoptera: Noctuidae) in Maize

Agrotis segetum nuclear polyhedrosis virus (AsNPV) and granulosis virus (AsGV), propagated in laboratory cultures of A. segetum in England and A. ipsilon in Spain, respectively, were applied to plots of maize plants at the one‐ to four‐leaf stage of growth. Plots were arranged in a 6 x 6 Latin square design and infested with second‐instar A. segetum larvae (the common cutworm). Each virus was applied in separate treatments by two application methods; as an aqueous spray containing 0.1% Agral as a wetting agent, and as a bran bait. The NPV was applied at a rate of 4 X 10¹² polyhedra/ha, and the GV at 4 X 10¹³ granules/ha. Soil and plants were sampled for larvae on three occasions following virus treatment: 24 h, 4 days and 11 days. The larvae were reared on diet in the laboratory, until death or pupation, to examine the rate and level of viral infection. Infection data showed 87.5% and 91% NPV infection and 12.5% and 55% GV infection in spray and bait treatments, respectively, in larvae sampled 24 h after treatment. In larvae sampled 4 days after treatment, the results were 78% and 100% NPV infection, and 13% and 6% GV infection. A total of only six larvae were retrieved on day 11. In both treatments larvae infected with AsNPV died significantly more rapidly and at an earlier instar than those infected with AsGV, indicating that AsNPV appears to have better potential as a control agent for A. segetum.     

Synthesis of the nuclear protein cyclin (PCNA) and its relationship with DNA replication

Synthesis of the nuclear protein cyclin (MW 36 000) and DNA in quiescent mouse fibroblasts is coordinately induced by serum and purified growth factors. Inhibition of DNA synthesis by hydroxyurea or aphidicolin in serum-stimulated quiescent cells does not affect the induction of cyclin. The levels of cyclin synthesis decrease rapidly at the end of the S phase. Immunofluorescence studies reveal that there are dramatic changes in the nuclear distribution of cyclin during S phase and that these depend on DNA synthesis or events during S phase. These observations strengthen the notion that cyclin is an important component of the events leading to DNA replication.     

Characterization of a 3''----5'' exonuclease activity in the phage phi 29-encoded DNA polymerase.

Purified protein p2 of phage phi 29, characterized as a specific DNA polymerase involved in the initiation and elongation of phi 29 DNA replication, contains a 3'----5' exonuclease active on single-stranded DNA, but not on double-stranded DNA. No 5'----3' exonuclease activity was found. The 3'----5' exonuclease activity was shown to be associated with the DNA polymerase since 1) the two activities were heat-inactivated with identical kinetics and 2) both activities, present in purified protein p2, cosedimented in a glycerol gradient.     

Characterization of the phage phi 29 protein p5 as a single-stranded DNA binding protein. Function in phi 29 DNA-protein p3 replication.

The phage phi 29 protein p5, required in vivo in the elongation step of phi 29 DNA replication, was highly purified from Escherichia coli cells harbouring a gene 5-containing plasmid and from phi 29-infected Bacillus subtilis. The protein was characterized as the gene 5 product by amino acid analysis and NH2-terminal sequence determination. The purified protein p5 was shown to bind to single-stranded DNA and to protect it against nuclease degradation. No effect of protein p5 was observed either on the formation of the p3-dAMP initiation complex or on the rate of elongation. However, protein p5 greatly stimulated phi 29 DNA-protein p3 replication at incubation times where the replication in the absence of p5 leveled off.     

Effects of neonatal undernutrition on the electrocortical development of the association areas in the rat

The electrocortical effects provoked by neonatal undernutrition and the environmental sensorial stimuli were studied in the cortical association areas of developing Wistar rats. When the interaction between these two factors was interfered (Experiment 1), the average frequency of the ECoG in the early starved rats was significantly increased than controls. Moreover, if these two factors were combined (Experiment 2) not significant differences in the ECoG average frequencies were observed. The data suggest that the maturation of cells underlying the ECoG in the association areas of the rat, requires not only an adequate supply of nutrients, but also the influence of sensory cues arising from the mother, littermates and the environmental surrounding.