Correlation of the insecticidal activity of the Bacillus thuringiensis A4 strain against Bactrocera oleae (Diptera) with the 140-kDa crystal polypeptide.

The crystals of the soil-isolated Bacillus thuringiensis (Bt) strain A4 consist of two polypeptides with molecular mass of 140 kDa and 32 kDa that exhibit insecticidal activity against adult flies of Bactrocera oleae (Diptera). Plasmid curing applied to this strain resulted in the isolation of several subclones exhibiting alterations in their crystal polypeptides as well as two acrystalliferous subclones. The crystals of subclone 1.1 lacked the 32-kDa polypeptide and consisted uniquely of a 140-kDa polypeptide antigenically related to the parental 140-kDa crystal polypeptide. Additionally, the crystals of this subclone exhibited insecticidal activity against B. oleae equivalent to that of the parental strain. Therefore, the 32-kDa crystal polypeptide is dispensable for insecticidal activity, which appears to be dependent on the presence of the 140-kDa crystal polypeptide.

Biological control of Bactocera oleae (Diptera: Tephritidae) using a Greek Bacillus thuringiensis isolate.

Bacillus thuringiensis, isolate 114A, was used in toxicity experiments against the wild population ofthe olive pest Bactroceria oleae (Gmelin). In laboratory experiments, spores and crystals of the B.t. were delivered to the insects with the food. Longevity, oviposition period, number of eggs produced, and percent hatch were recorded. Olive fruits from the oviposition test were dipped into a suspension containing spores and crystals of B. thuringiensis 114A after the eggs were deposited. In field experiments, four to six sprayings per year of B.t. 114A isolate were applied for three successive years. It was found that, in addition to the longevity of B. oleae, the oviposition period, number of eggs and percent egg hatch decreased. Also, the percentage of pupation and emergence was reduced when olive fruits with eggs in their mesocarp were dipped in the solution of spores and crystals. Field applications with the toxins of 114A isolate of B. thuringiensis have resulted in significant protection of the olive production.

Insecticidal activity of strains of Bacillus thuringiensis on larvae and adults of Bactrocera oleae Gmelin (Dipt. Tephritidae).

The olive fly, Bactrocera oleae, is the key pest on olives in the Mediterranean area. The pest can destroy, in some cases, up to 70% of the olive production. Its control relies mainly on chemical treatments, sometimes applied by aircraft over vast areas, with their subsequent ecological and toxicological side effects. Bacillus thuringiensis is a spore-forming soil bacterium which produces a protein crystal toxic to some insects, including the orders of Lepidoptera, Diptera, and Coleoptera and other invertebrates. The aim of this study was to search for isolates toxic to B. oleae. Several hundred B. thuringiensis isolates were obtained from olive groves and olive presses in different areas of Greece, Sardinia (Italy), and Spain and from cooperating scientists throughout the world. Some isolates were found toxic only to adults or larvae and some to both stages of the olive fly. In addition, the most toxic isolates were assayed on Opius concolor Szepl. (Hym. Braconidae), the most important parasitoid of the olive fruit fly. Only 3 isolates out of 14 gave significant mortality against this parasitoid. Several of the most toxic crystalliferous isolates may contain novel toxins since they gave no PCR products when probed with primers specified for 39 known toxin genes.

Sex hormone binding globulin inhibits strongly the uptake of estradiol by human breast carcinoma cells via a deprivative mechanism.

A controversy exists for many years about the role of sex hormone binding globulin (SHBG) in the uptake of estradiol by the cells. Using the estradiol-sensitive human breast carcinoma cell line MCF-7 and SHBG isolated from human serum by a new method, we observed a strong inhibition of estradiol uptake. The inhibition was higher when the concentration of the hormone was low. On the other hand, there seemed to be a lag period in inhibition when the concentrations of SHBG were very low, followed by an exponential increase, when the concentration exceeded a critical value. The inhibitory activity was higher when SHBG was added before or along with estradiol in the cell culture, as well as when the incubation period was elongated, while was dramatically minimized by the presence of dihydrotestosterone. Despite the inhibition of estradiol uptake caused by SHBG, the distribution of the hormone in various cell components remained practically the same. In conclusion, all indications from experimental data seem to suggest a simple deprivative mechanism being responsible for the inhibitory activity of SHBG on estradiol uptake by MCF-7 cells in culture.

Distribution and characterization of Bacillus thuringiensis in the environment of the olive in Greece.

The distribution of Bacillus thuringiensis in Greece, was studied and the presence of this organism was found in 11.2% of the samples collected. The characterization of the different isolates was based on their whole-cell protein profiles. Some of the isolates form quite unusual parasporal inclusions.

Plasmid patterns of Bacillus thuringiensis strains and isolates.

Bacillus thuringiensis produces crystal proteins which are toxic to several orders of economically important insects and other invertebrates. The genes encoding these toxins reside mainly on plasmids. This report consists of a comparative analysis of the plasmid content of a number of B. thuringiensis strains and isolates which may facilitate the search for novel toxin genes and other important products of this organism.

Mitotic and polytene chromosome analysis in Dacus oleae (Diptera: Tephritidae).

The present study constitutes the first attempt to construct a photographic map of the polytene chromosomes of Dacus oleae, a pest of the olive tree that causes serious financial damage in all olive oil producing countries. The map was constructed by using the larval fat body cells, the chromosomes of which are representative of the polytene chromosomes of other polytene tissues. In addition, the mitotic chromosomes of brain ganglia were examined, permitting tentative correlations between mitotic and polytene elements. This investigation shows that D. oleae is suitable for cytogenetic analysis in both mitotic and polytene chromosomes, a fact that may prove very useful for obtaining more detailed genetic information on the pest's natural populations.

Toxicity of Bacillus thuringiensis to laboratory populations of the olive fruit fly (Dacus oleae).

A survey of Bacillus thuringiensis recovered from the environments of olive groves in Greece was carried out. Of 80 soil samples, 24 were found to contain B. thuringiensis with parasporal crystal inclusions; these were tested for toxicity against the olive fruit fly (Dacus oleae). Mortality levels of larvae caused by the different isolates varied from 7 to 87%. Higher levels of mortality were observed if a mixture of relatively pure crystals and spores was used compared with the mortality resulting from either fraction alone. We were able to show that the toxicity of the most active isolate is likely to be specific for D. oleae.

Effect of interferon on the accumulation of RNA transcripts of genes coding for cellular and viral proteins.

Using plasmids containing sequences complementary to the genes that code for oligo-2',5'-adenylate synthetase, actin and H4 histone, we have shown that although interferon does not affect the accumulation of RNA transcripts of the actin and H4 histone genes, it activates the accumulation of RNA transcripts of the oligo-2',5'-adenylate synthetase gene. However, interferon inhibits the accumulation of RNA transcripts of simian virus 40 (SV40) genes in SV40-infected cells.

Induction of 2',5' oligo(A) synthetase in Vero cells.

2',5' oligo(A) synthetase can be induced in Vero cells with interferon; maximal levels are reached after treatment for 24 hours. This induction is a result of increased accumulation of RNA transcripts of the specific gene.

Induction of 2',5'oligo (A) synthetase in animals bearing Ehrlich ascites tumor cells.

The activity of 2',5'oligo(A) synthetase in experimental mice inoculated with poly(I) poly(C) is higher in the animals with transplantable tumors (Ehrlich Ascites Tumor cells) compared to animals without the tumor. The higher enzymatic activity is detected in tissue homogenates from liver and spleen, as well as in homogenates from the Ascites cells.

An inapparent infection with a probable picornavirus in several stocks of laboratory reared and naturally occurring populations of Dacus oleae Gmel. pupae in Greece.

Pupae from several stocks of wild and laboratory reared olive fruit fly, Dacus oleae, were fractionated by a series of steps designed to identify occluded and nonoccluded viruses. Two different size of particles were isolated, the smaller of which contained a single-stranded RNA molecule of about 2.8 x 10(6). This small RNA virus was found to inapparently infect a Ceratitis capitata continuous cell line.

Studies on the effect of homo-aza-steroidal ester of p-bis (2-chloroethyl) amino phenyl acetic acid in Ehrlich ascites tumor cells.

The effect of a homo-aza-steroidal ester (ASE) on the incorporation of radioactive precursor to DNA of Ehrlich ascites tumor (EAT) cells has been investigated. We found that treatment of cells with 80 micrograms/ml of ASE for 2 hours causes an inhibition of the incorporation of 3H-thymidine to DNA by 71%. This is partly because ASE affects the radioactive thymidine pool in the cell. The DNA from EAT cells after centrifugation in CsCl is shifted to higher densities when ASE is present throughout the experiment. This density shift was not observed when ASE was incubated only in the growth medium of the cells.

Induction of 2',5' oligo(A) synthetase in tumor-bearing mice with encephalomyocarditis (EMC) virus or poly(I)poly(C).

Infection of 13 month-old C3H mice with EMC virus or inoculation with the interferon inducer poly(I)poly(C) results in elevated levels of the enzyme 2',5' oligo(A) synthetase only in animals with spontaneous tumors (breast cancer or hepatomas). High enzymatic activities are detected in homogenates from liver, spleen, plasma and neoplastic cells of the animals with breast carcinomas and only in the neoplastic liver cells of the animals with hepatomas.

Products of 2',5'-oligo(A) synthetase in interferon treated Daudi cells.

Cell extracts from interferon treated Daudi cells contain 2',5'-oligo(A) synthetase which upon incubation with ATP produce predominantly trimers.

Interaction of homo-aza-steroidal ester of [p-[bis-(2-chloroethyl) amino]phenyl]acetic acid (ASE) with DNA of Ehrlich ascites tumor cells.

A cytostatic, homo-aza-steroidal ester of [p-[bis-(2-chloroethyl) amino]phenyl]acetic acid (ASE) was reduced with NaB3H4 and [3H]ASE-treated DNA prepared in vitro. We found that: (1) ASE reacts preferentially with purines; (2) ASE decreases the thermal stability of the double helix upon binding to DNA; (3) [3H]ASE binding sites are clustered along the DNA molecules; (4) ASE binding sites probably represent oligo- or polypurine sequences.

2'-5' oligo(A) synthetase levels in interferon-sensitive or -resistant lymphoid cells.

The activity of 2'-5' oligo(A) synthetase has been measured both in control and interferon-treated lymphoid cells. While control or interferon-treated Raji and Namalwa cells exhibit low activity of the 2'-5' oligo(A) synthetase, the activity of this enzyme is increased 20-fold when Daudi cells are treated with the same dose of human interferon. The same enzyme is induced by interferon in R3HR-1 cells to a lesser extent.

Presence of double stranded regions of viral RNA in infected cells.

Ribonuclease treatment of rhinovirus-infected human embryo lung cells after cell disruption reveals that double stranded RNA is present in the preparation before nucleic acids are extracted with phenol. This shows that the hydrogen bonding between complementary molecules of viral RNA which occurs in infected cells is not a result of the extraction of RNA with phenol.

Mode of integration of Epstein-Barr virus genome into host DNA in Burkitt lymphoma cells.

The ebv dna integrated into the host genome from cell of an African Burkitt lymphoma biopsy has been compared to the corresponding fraction of EBV DNA from the cell line SU-AmB-2 which is of American Burkitt lymphoma origin. It is shown that while, in the case of the African biopsy, large pieces of EBV DNA sequences are integrated into the host DNA, much smaller pieces of virus DNA are integrated into the DNA of the SU-AmB-2 cells. The possibility that this difference might be related to the fact that EBV is rarely associated with Burkitt lymphomas outside East Africa is discussed.