Salmonella enterica subsp. enterica serovar Enteritidis harbours ColE1, ColE2, and rolling-circle-like replicating plasmids

Using DNA hybridization, at least three distinct groups of low molecular mass plasmids were identified in Salmonella enterica subsp. enterica serovar Enteritidis. After sequencing representative plasmids from each group, we concluded that they belonged to ColE1, ColE2, and rolling-circle-like replicating plasmids. Plasmid pK (4245 bp) is a representative of widely distributed ColE1 plasmids. Plasmid pP (4301 bp) is homologous to ColE2 plasmids and was present predominantly in single-stranded DNA form. The smallest plasmids pJ (2096 bp) and pB (1983 bp) were classified as rolling-circle-like replicating plasmids. Both encoded only a single protein essential for their own replication, and they must have existed in an unusual molecular structure, as (i) they were capable of hybridization without denaturation, (ii) their DNA could be linearized with S1 nuclease, and (iii) even after such treatment, the ability to hybridize without denaturation did not disappear.     

Secular change in body height and cephalic index of Croatian medical students (University of Rijeka)

An investigation of body height and cephalic measurements was performed among five groups of first-year medical students of the University of Rijeka School of Medicine (Rijeka, Croatia). Body height and different cephalic measurements showed normal distribution, both in male and female students. Differences between measured variables were statistically analyzed by ANOVA. No significant difference with regard to year of birth was found in either males or females. The cephalic index showed no statistically significant difference between sexes or with regard to body height, while head breadth and length correlated significantly with birth year and body height, both in males and females. Head breadth decreased within the study period, while head length increased. Results were compared with those of similar studies from the mid-20th century. Student's t-test showed a significant change of cephalic indices and other head measurements, but not of body height, in males. The frequency difference between various head shapes was tested using the chi-square test. A significant increase of dolichocephalic and mesocephalic and a significant decrease of brachycephalic head shape were found in both sexes. These results suggest a continuity of the debrachycephalization process observed in our population at the past midcentury.     

Arg-vasopressin increases proliferation of human osteoblast-like cells and decreases production of interleukin-6 and macrophage colony-stimulating factor

Patients with arginine-vasopressin (AVP) deficiency have been reported to have a decreased bone mass. The mechanism behind this is not known. In this study, the effects of AVP on primary human osteoblast-like (hOB) cells and SaOS-2 cells were investigated. Cell proliferation was measured by [3H]thymidine incorporation or a commercially available kit (EZ4U), and protein synthesis by [3H]proline incorporation. In addition, the production of interleukin-6 (IL-6) and macrophage colony-stimulating factor (M-CSF) in hOB cells was determined. AVP at 10-100 pmol/l increased cell proliferation in hOB and SaOS-2 cells (p < 0.05). Protein synthesis increased in SaOS-2 cells incubated with 10-100 pmol/l AVP (p < 0.01). When hOB and SaOS-2 cells were incubated with AVP together with a vasopressin receptor-1 (V1)-antagonist ([beta-Mercapto-beta,beta-cyclopenta-methylenepropionyl1,O-Me-Tyr2,Arg8]-vasopressin) or a protein kinase C (PKC)-inhibitor (chelerythrine) the increase in cell proliferation in response to AVP was abolished. The production of IL-6 and M-CSF was decreased in hOB-cells incubated with 10 pmol/l AVP (p < 0.01). In addition, by RT-PCR, we found evidence for expression of mRNA for the vasopressin 1a (V1a)-receptor in hOB cells. In conclusion, AVP stimulated proliferation of hOB- and SaOS-2 cells. We suggest that the effect was mediated through the V1-receptor. Additionally, AVP decreased production of IL-6 and M-CSF from the hOB cells. Moreover, the V1a-receptor seems to be expressed in hOB cells.     

Caries and oral hygiene in children in postwar Novi Travnik (Bosnia and Herzegovina) and Zabok (Croatia)

The study was performed in 1997 and involved school children between the age of 6 and 12 in Novi Travnik, Bosnia and Herzegovina (n = 203) and Zabok, Croatia (n = 132). OHI-S (Simplified Oral Hygiene Index by Green-Vermillion) and DMF (Decayed, Missing, Filled) index were used as main outcome measures. Prewar data were taken from the respective literature. The value of the DMF/dmf (PERMANENT/deciduous teeth) for six-year-olds in Novi Travnik of the period before the war was: d = 5.6, m = 0.4, f= 0.6 and D = 0.3, F = 0.1 and the average DMF index of twelve-year-olds for the same period were 6.5. The DMF/dmf index in 1997 in Novi Travnik was: d = 9.4+/-4.4; m = 0.7 +/-1.1; D = 1.9+/-1.2 and average DMF index of twelve-year-olds was 9.0+/-4.16. The DMF index of twelve-year-olds in Zabok in 1990 was 3.4 and 4.1+/-2.1 in 1997. Total DMF index for all the examined ages in 1997 for Zabok was 6.1+/-3.7 and for the examinees in Novi Travnik 10.5+/-4.1 (p<0.001). Similarly, the OHI-S in 1997 for Zabok was 1.0+/-0.7 whereas 1.7+/-0.7 (p<0.001) in Novi Travnik. In comparison to prewar data, DMF index in 1997 was considerably higher. Increase of DMF index was higher in Novi Travnik than in Zabok, which can be attributed to the war and wartime conditions.     

Diurnal variation of cytokinin, auxin and abscisic acid levels in tobacco leaves

As many processes are regulated by both light and plant hormones, evaluation of diurnal variations of their levels may contribute to the elucidation of the complex network of light and hormone signal transduction pathways. Diurnal variation of cytokinin, auxin, and abscisic acid levels was tested in tobacco leaves (Nicotiana tabacum L. cv. Wisconsin 38) grown under a 16/8 h photoperiod. The main peak of physiologically active cytokinins (cytokinin bases and ribosides) was found after 9 h of light, i.e. 1 h after the middle of the light period. This peak coincided with the major auxin peak and was closely followed by a minor peak of abscisic acid. Free abscisic acid started to increase at the light/dark transition and reached its maximum 3 h after dark initiation. The content of total cytokinins (mainly N-glucosides, followed by cis-zeatin derivatives and nucleotides) exhibited the main peak after 9 h of light and the minor peak after the transition to darkness. The main, midday peak of active cytokinins was preceded by a period of minimal metabolic conversion of tritiated trans-zeatin (less than 30%). The major cytokinin-degrading enzyme, cytokinin oxidase/dehydrogenase (EC 1.5.99.12), exhibited maximal activity after the dark/light transition and during the diminishing of the midday cytokinin peak. The former peak might be connected with the elimination of the long-distance cytokinin signal. These cytokinin oxidase/dehydrogenase peaks were accompanied by increased activity of beta-glucosidase (EC 3.2.1.21), which might be involved in the hydrolysis of cytokinin O-glucosides and/or in fine-tuning of active cytokinin levels at their midday peak. The achieved data indicate that cytokinin metabolism is tightly regulated by the circadian clock.     

Potential of <Emphasis Type="Italic">Rhodococcus erythropolis</Emphasis> as a bioremediation organism

Summary The capability of Rhodococcus erythropolis CCM 2595(ATCC 11048) to utilize phenol, pyrocatechol, resorcinol, p-nitrophenol, p-chlorophenol, hydroquinone and hydroxybenzoate, respectively, or as respective binary mixtures with phenol, was described. This capability was found to depend on the substrate and its initial concentration. Some monoaromatic compounds had a suppressive effect on the strain’s ability to utilize phenol in a binary mixture and easily utilizable monoaromatics were strong inducers of the phenol 2-monooxygenase (EC 1.14.13.7). The capacity of R. erythropolis to colonize a synthetic zeolite was demonstrated and the enhancement of phenol tolerance of biofilms utilizing phenol was observed. The effect of humic acids on phenol killing was described and discussed as well. To allow use of recombinant DNA technology for strain improvement, methods of genetic transfer (transformation and conjugation) in R. erythropolis were established.     

The effect of humic acid on transamination in winter wheat plants

A very low, for the most part unmeasurable glutamic-aspartio transminase activity and a very high glutamic-alanine transaminase activity was found in the overground parts and roots of young wheat plants. The roots had a higher glutamic-alanine transaminase activity than the overground parts in the first and second leaf stage. Plants cultivated in Knop’s nutrient solution (variant with humate and without) showed a higher glutamic-alanine transaminase activity than poorly growing plants, cultivated in distilled water (with humate and without). In plants cultivated in nutrient solutions, transaminase activity increased with the age of the wheat plants. As in the previous experiments, the effect of humate was only significant, in the roots of plants cultivated in distilled water with humate, where transamination activity was greater than in the control without humate. The roots of this variant with a stimulatory growth effect showed a large accumulation of free sugars in the previous experiments. The connection between these effects of humate on the roots of young winter wheat plants is discussed.     

Isolation and characterization of a new ruminal bacteriophage lytic toStreptococcus bovis

A new bacteriophage, designated F4, was isolated from the ruminal fluid of a calf. The host range of F4 phage was limited to five strains ofStreptococcus bovis out of ten tested on which clear plaques 0.6–1.2 mm in diameter were found. Bacteriophage F4 had an elongated head 75 nm long and 33 nm wide with a noncontractile flexible tail 100 nm in length on average. This phage is defective in the generation of plaques at low multiplicities of infection. Its genome consists of double-stranded linear DNA of 60.38 kb lacking cohesive ends. The F4 DNA was analyzed with 13 restriction enzymes. The restriction enzymes that did not cleave it wereBamHI,EcoRI,PvuI, andSmaI. The circular restriction map was constructed with four restriction endonucleases (XbaI,EcoI,SalI, andBglI).     

Necrosis predominates in the cell death of human colon adenocarcinoma HT-29 cells treated under variable conditions of photodynamic therapy with hypericin.

Photodynamic therapy (PDT) represents a new rapidly-developing anticancer approach based on administration of a non- or weakly-toxic photosensitizer and its activation with light of appropriate wavelength. Hypericin, one of the promising photosensitizers, is known to induce apoptosis with high efficiency in various cell line models. However, here we report the prevalence of necrosis accompanied by suppression of caspase-3 activation in colon adenocarcinoma HT-29 cells exposed to an extensive range of PDT doses evoked by variations in two variables -- hypericin concentration and light dose. Necrosis was the principal mode of cell death despite different PDT doses and the absence of anti-apoptotic Bcl-2 expression, even if the same condition induced caspase-3 activity at similar toxicity in HeLa cells. Introduction of Bcl-2 into HT-29 cells invoked caspase-3 activation, changed the Bcl-X(L) expression pattern, increased the apoptosis ratio with no effect on overall toxicity, and supported arrest in the G(2)/M-phase of cell cycle. Since it is known that Bcl-2 suppression in HT-29 is reversible and linked to the over-expression of mutated p53 and also considering our data, we suggest that the mutation in p53 and events linked to this feature may play a role in cell death signalling in HT-29 colon cancer cells.