Differences in haemolymph proteins in relation to diapause and wing dimorphism inPyrrhocoris apterus (L.) (Heteroptera: Pyrrhocoridae)

Three different cultures of dimorphic bug,Pyrrhocoris apterus, were analyzed concerning diapause and its relation to wing morph pattern. The proportion of macropterous bugs was considerably higher (36%) in the Mediterranean culture from Israel than that (1.3%) in the temperate culture from the Czech Republic. The macropterous morph- and brachypterous morphrelated types of reproduction arrest, differing by the length of pre-oviposition period, were distinguished in cultures analyzed. The reproduction arrest with an average pre-oviposition period of 38.2 days in Mediterranean macropters and 18.5 days in macropters from selected macropterous strain, was found to be typical for macropterous morph. Two different photoperiodic conditions induced macropterous morph-related reproduction arrest, the long-day (18 h light-6 h dark) photoperiod in macropterous strain macropters and the short-day (12 h light-12 h dark) photoperiod in Mediterranean macropters. The brachypterous morph-related reproduction arrest, characterized by pre-oviposition period longer than 90 days, occurred predominantly in diapausing brachypterous bugs. While the hibernal diapause of brachypterous bugs was characterized by a very high level of the 78- and 82-kDa proteins in haemolymph, their content in haemolymph of macropters during macropterous morph-related reproduction arrest was almost as low as in the reproductive adults. The variation of reproduction arrest in relation to wing dimorphism represents an important feature in the life strategy ofP. apterus.     

Complex repair kinetics of DNA strand breaks induced by γ-rays or UV radiation in Ehrlich ascites tumour cells

Fluorometric analysis of DNA unwinding (FADU) – a sensitive technique for the detection of strand breaks in DNA – has been modified and used for the detailed investigation of repair kinetics of DNA-strand breaks arising under different conditions in Ehrlich ascites tumour (EAT) cells irradiated by γ-rays or ultraviolet (UV) radiation. The repair kinetics of DNA-strand breaks induced in EAT cells by γ-radiation was measured at radiation doses of 8, 20 and 50 Gy. We found complex repair curves in all cases, probably reflecting the combined processes of break rejoining and break generation during repair. In order to affect the above-mentioned processes, we have used different conditions of repair and different types of radiation. Lowering of the temperature of incubation and treating the cells by 5-fluoro-2′-deoxyuridine (FUdR) lead to complex changes of the repair curve with a reduced ``wave' pattern. In order to change the type of damage to DNA, we used UV radiation (254 nm, 10 and 20 J/m²). Detailed studies of the repair kinetics showed that the repair curve for 10 J/m² had a second maximum within 70 min after irradiation. Received: 17 May 1995 / Accepted in revised form: 15 March 1996     

Hardening by abscisic acid of tobacco plantlets grownin vitro

Tobacco plantlets were grownin vitro on Murashige and Skoog’s medium with2 % of saccharose. Addition of 0.01 mM abscisic acid (ABA) into the medium decreased stomatal conductance of the adaxial epidermis and especially the abaxial epidermis without negative effects on growth parameters. As a result the rate of water loss from ABA-treated plantlets taken out of cultivation vessels was slower than that of control plantlets. This could help their acclimation after transplantation toex vitro conditions.     

The effect of virus infection on morphology and protein components of pollen grains

Morphology of pollen grains collected from healthy and virus infected plants ofChenopodium quinoa L.,Chenopodium album L. andNicotiana tabacum L. cv. Samsun was investigated using scanning electron microscopy (SEM). Pollen grains from tobacco plans infected with tobacco mosaic virus (TMV) were smaller, with rounded shape and conspicuous deformation of aperture unlike oval and smooth pollen grains from healthy plants. No morphological alterations were observed inC. quinoa andC. album plants infected with TMV and cucumber mosaic virus (CMV). Polyacrylamide gel electrophoresis of pollen proteins revealed substantial quantitative and qualitative differences in protein components of pollen grains collected from healthy and virus infected plants     

Comparison of the solution and crystal conformations of (G + C)-rich fragments of DNA.

DNA fragments crystallize in an unpredictable manner, and relationships between their crystal and solution conformations still are not known. We have studied, using circular dichroism spectroscopy, solution conformations of (G + C)-rich DNA fragments, the crystal structures of which were solved in the laboratory of one of the present authors. In aqueous trifluorethanol (TFE) solutions, all of the examined oligonucleotides adopted the same type of double helix as in the crystal. Specifically, the dodecamer d(CCCCCGCGGGGG) crystalized as A-DNA and isomerized into A-DNA at high TFE concentrations. On the other hand, the hexamer d(CCGCGG) crystallized in Z-form containing tilted base pairs, and high TFE concentrations cooperatively transformed it into the same Z-form as adopted by the RNA hexamer r(CGCGCG), although d(CCGCGG) could isomerize into Z-DNA in the NaCl + NiCl2) aqueous solution. The fragments crystallizing as B-DNA remained B-DNA, regardless of the solution conditions, unless they denatured or aggregated. Effects on the oligonucleotide conformation of 2-methyl-2,4-pentanediol and other crystallization agents were also studied. 2-Methyl-2,4-pentanediol induced the same conformational transitions as TFE but, in addition, caused an oligonucleotide condensation that was also promoted by the other crystallization agents. The present results indicate that the crystal double helices of DNA are stable in aqueous TFE rather than aqueous solution.     

Effect of anti-herpes specific transfer factor

Using a blood cell separator, lymphocytes were collected from otherwise healthy convalescents suffering from herpetic infections. A specific anti-herpes dialysate (AH-DLE) was prepared from the lymphocytes, using standard procedures. Patients with recurrent herpetic infections were treated with a single dose of the dialysate, at the initial signs of herpetic infection (group A), with two doses (group B) or with three doses (group C). A total number of 37 patients (29 women, 8 men, age range 15–73 years) were treated. No improvement was observed in 7 patients (18.9%), whilst 7 patients did not manifest any exacerbation of their herpetic infection in the course of the one-year follow-up. The remaining 62.2% of the patients showed a marked improvement: decrease of the frequency and/or duration or relapses. Before AH-DLE administration, the mean number of herpes relapses in this group of patients was 12 p.a.. After therapy, the number of relapses decreased to 3.5 p.a.. No statistically significant difference was observed between groups A and B. The least favourable results were registered in group C. However, this group included 6 female patients extremely resistant to the previously therapeutic attempts, including inosiplex, non-specific DLE or acyclovir. Thus, even in this group, the therapy was successful in 50% of the patients.     

Organization of telomeric and subtelomeric chromatin in the higher plant Nicotiana tabacum

We have examined the structure and chromatin organization of telomeres in Nicotiana tabacum. In tobacco the blocks of simple telomeric repeats (TTTAGGG)_n are many times larger than in other plants, e.g., Arabidopsis thatiana or tomato. They are resolved as multiple fragments 60–160 kb in size (in most cases 90–130 kb) on pulsed-field gel electrophoresis (PFGE) of restriction endonuclease-digested DNA. The major subtelomeric repeat of the HRS60 family forms large homogeneous blocks of a basic 180 by motif having comparable lengths. Micrococcal nuclease (MNase) cleaves tobacco telomeric chromatin into subunits with a short repeat length of 157±5 bp; the subtelomeric heterochromatin characterized by tandemly repeated sequences of the HRS60 family is cut by MNase with a 180 by periodicity. The monomeric and dimeric particles of telomeric and subtelomeric chromatin differ in sensitivity to MNase treatment: the telomeric particles are readily digested, producing ladders with a periodicity of 7 bp, while the subtelomeric particles appear to be rather resistant to intranucleosomal cleavage. The results presented show apparent similarities in the organization of telomeric chromatin in higher plants and mammals.     

Oxygen and/or glucose limitation in a chemostat culture of Candida utilis mathematical model identification

The glucose and/or dissolved oxygen limited continuous culture of yeast Candida utilis was studied. Six different mathematical models were designed to describe and analyze the experiments. The model considering the production of surface active compounds at autoanaerobic conditions and dissolved oxygen consumption for nongrowth associated exogeneous respiration yields the best fit. The results may be applied for aerobic waste water treatment plants, process analysis and simulation.     

Ecological requirements and recent European distribution of the aquatic carnivorous plantAldrovanda vesiculosa L.—A review

Aldrovanda vesiculosa, a critically endangered aquatic carnivorous plant, is a species rapidly vanishing from Europe. A map of its recent European distribution is given. Of its earlier distribution area covering a substantial part of Europe, only a few native sites in Hungary, Poland, Romania, Russia and Ukraine remain. On the basis of the literature, field research inAldrovanda habitats, and experience of its cultivation both in culture and in the field, its ecological requirements and habitat characteristics are reviewed. The most important requirements appear to be a high CO₂ concentration, a medium concentration of humic acids in the water, warm water of high transparency, and a very low biomass of accompanying aquatic plants. The possibility of forming new substitute localities ofAldrovanda is discussed.