Prostaglandin production by human peripheral blood monocytes changes with in vitro differentiation

To investigate the influence of in vitro culture on prostaglandin (PG) production, human monocyte-enriched peripheral blood mononuclear cells were isolated and incubated on gelatin-coated plates. On days zero, five and eleven of culture, the cells were examined microscopically and the production of PGF_2α, PGE₂, PGD₂, F metabolite (PGFM) and E metabolite (PGEM) were measured by radioimmunoassay. Differences in PG output were analyzed using the Wilcoxon and Friedman tests. Freshly isolated human peripheral blood monocytes produced mainly PGE₂. In vitro, however, PGE₂ production decreased from 196 (48–288) fmol/10⁶ cells per 3h on day zero of culture to 28 (6–51) on day eleven (p=0.04); median (range), n=7. Prostaglandin D₂ and PGEM output decreased similarly, but these differences failed to reach significance. Prostaglandin F_2α and PGFM output, on the other hand, increased from 32 and 19 fmol/10⁶ cells per 3h, respectively, on day zero of culture to 127 (p<0.05) and 58 (p=0.01) on day eleven. Changes in PG output were associated with in vitro differentiation as evidenced by changes in cellular morphology. These result suggest that differentiation of human peripheral blood monocytes in vitro is accompanied by a shift in PG output from PGE₂ and PGD₂, towards PGF_2α.     

Clostridium acetobutylicum Protoplast Formation and Regeneration

Techniques and media for the production and regeneration of stable Clostridium acetobutylicum protoplasts are described.     

Deoxyribonucleic Acid Repair in Bacteriophage T4: Observations on the Roles of the x and v Genes and of Host Factors

Studies were carried out to determine the effect of mutation in the host pol I gene on survival of ultraviolet (UV)-irradiated bacteriophage T4. Whereas a slightly reduced survival was observed in Escherichia coli strain P-3478 (pol A(1)) compared to strain W-3110 (pol A(+)), no such difference was observed in two strains isogenic except for the pol A gene. It was also shown that, whereas bacteriophage T4x is sensitive to UV irradiation, X irradiation, and treatment with methyl-methanesulfonate (MMS), phage T4v(1) is sensitive only to UV irradiation. The survival of damaged phage T4x is neither affected by the presence of the rec A, rec B, or pol A mutations in the host, nor is there evidence that phage T4 effects repair of rec A or pol A mutants previously treated with either UV or MMS.     

Cell kinetics,development of stomata and some effects of colchicine in barley

Summary The developmental sequence of the formation of stomatal complexes in the leaf epidermis of barley was studied. Cell-kinetic parameters were obtained from two genotypes — Early Bonus and eceriferum-g, a mutant with an abnormal stomatal pattern. The distribution of mitotic frequencies as a function of position in the stomatal rows was analyzed at each stage of development leading to mature stomata. Regression curves obtained for each stage showed that the distributions were stage-specific. Thus, the mitotic frequencies presented similar values throughout the portion of the file where the first asymmetrical divisions take place, had a parabolic distribution for the stage of subsidiary formation, and showed a linear shape, with a negative slope, for the stage of guard-mother-cell divisions. The mutant genotype differed from the normal by having a faster rate of ordinary guard-mother-cell divisions as a function of position in the row. The higher level of subsidiary cell formation in the mutant was interpreted as a consequence of a displacement of the used markers, suggesting a precocious initiation of subsidiary-cell formation in eceriferum-g. Time estimations of the length of the cell cycles were obtained by cell-population studies after a pulse with colchicine. Eceriferum-g appeared to have slower cell cycles. The leaves treated with colchicine showed a shift in the elongation axis of the cells. Autoradiography after treatment with ³H-thymidine showed ineorporation of the label in the portions of the row proximal to all three peaks of divisions indicating that all mitoses were preceded by the usual period of DNA synthesis. Labelling of lateral cells at a mature stage suggested DNA synthesis leading to endoploidy.     

3. Protein diets for obesity: metabolic and clinical aspects

The alleged benefits of protein diets remain unproven, since research data on the safety and long-term utility of protein products as the principal or only source of nutrients for weight reduction programs are as yet insufficient. First, it is uncertain whether the decreases in body protein turnover occurring with these diets are consistent with normal function over long periods, though net balance of protein is obtained. Second, the main advantage to the patient is the suppression of appetite by the ketoacidosis, but it is the ketoacidosis that causes many of the untoward effects. Third, the addition of carbohydrate to a protein diet does not mitigate the benefit of the protein and prevents most of the untoward effects. Fourth, there is clearly no advantage of “predigested” proteins (which are generally poorer in quality than normal high-protein foods) except for the psychologic factor of being given “medication” for the “disease” of obesity. Fifth, there is a distinct danger of deficiencies of micronutrients developing with prolonged consumption of unsupplemented diets. Sixth, the cardiac disorders associated with death in persons taking these diets have not been shown to be coincidental rather than a direct consequence of the diets.In the present state of understanding of protein diets, they should be supervised only by specially trained physicians in rigorous multidisciplinary programs, preferably those with ongoing research. Only individuals free from contraindications should be so treated. Until compelling data proving the safety and efficacy of these diets are forthcoming, the general public should be counselled against their use.     

The mutagenicity of heterocyclic N-nitrosamines for Salmonella typhimurium

14 carcinogenic and noncarcinogenic heterocyclic N-nitrosamines were evaluated for mutagenicity to Salmonella typhimurium TA-1535, which responds to mutagens inducing base-pair substitutions. Both suspension and plate tests were used, with mouse and rat liver in vitro metabolic activation systems.All carcinogenic nitrosamines showed a positive response in at least one test system, as did the noncarcinogens. In general, the mutagenic responses obtained with mouse liver were equal to, or greater than, the responses obtained with rat liver in both the suspension and plate tests. Although it is difficult to make quantitative comparisons between plate and suspension tests, both systems appeared to be responsive to the same dose ranges for the individual nitrosamines.     

Stomata from npq1, a zeaxanthin-less Arabidopsis mutant, lack a specific response to blue light

The Arabidopsis mutant npq1, which cannot accumulate zeaxanthin because of a defective violaxanthin deepoxidase, was used to investigate the role of zeaxanthin in the stomatal response to blue light. Neither dark-adapted nor light-treated guard cells or mesophyll cells of the npq1 mutant contained detectable zeaxanthin. In contrast, wild-type guard cells had a significant zeaxanthin content in the dark and accumulated large amounts of zeaxanthin when illuminated. The well-documented red light enhancement of blue light-stimulated stomatal opening, in which increasing fluence rates of background red light result in increased response to blue light, was used to probe the specific blue light response of Arabidopsis stomata. Stomata from the npq1 mutant did not have a specific blue light response under all fluence rates of background red light tested. On the other hand, stomata from leaves of hy4 (cry 1), an Arabidopsis mutant lacking blue light-dependent inhibition of hypocotyl elongation, had a typical enhancement of the blue light response by background red light. The lack of a specific blue light response in the zeaxanthinless npq1 mutant provides genetic evidence for the role of zeaxanthin as a blue light photoreceptor in guard cells.     

A comprehensive catalogue of somatic mutations in cancer genomes

This Hot Topics contribution considers two recently published papers that demonstrate the utility of advanced DNA sequencing technologies for identifying classes of mutations other than base substitutions. Data are presented from genome analyses of immortalized cell lines derived from a malignant melanoma and a small cell carcinoma of the lung. Among other observations the studies suggest the operation of novel DNA repair mechanisms or modes.     

Range-wide phylogeography of Juniperus thurifera L., a presumptive keystone species of western Mediterranean vegetation during cold stages of the Pleistocene

We investigate the range-wide population structure and phylogeography of thuriferous juniper (Juniperus thurifera L.), a species with a highly disjunct distribution in the western Mediterranean. We genotyped a total of 327 individuals from 20 populations using amplified fragment length polymorphisms (AFLP). Different analyses such as principal co-ordinate analysis (PCoA), nonmetric multidimensional scaling of F(ST) distances among populations, unweighted pair group method with arithmetic mean (UPGMA), and Bayesian clustering revealed that the Strait of Gibraltar acted as an efficient barrier against gene flow between the Moroccan and European populations for a very long time, and consequently support that the Moroccan populations should be recognised as a distinct subspecies (J. thurifera L. subsp. africana (Maire) Romo and Boratyńsky). The Algerian population was genetically more closely related to the European than to the Moroccan ones, probably due to dispersal events from Europe to Algeria. With respect to the mainland European populations, our data are not conclusive to reject any of the two following hypotheses: (1) the Iberian Peninsula was subdivided into different gene pools, and was the source for the colonisation of the Pyrenees and the Alps; and (2) the pattern we see today is partly the result of immigration into the Iberian Peninsula, e.g. from the Alps. Finally, the Corsican population was closely related genetically to two northern Iberian populations most probably due to relatively recent long-distance dispersal.