Research on the ability of propionic acid and vitamin B12 biosynthesis by <Emphasis Type="Italic">Propionibacterium freudenreichii</Emphasis> strain T82

The purpose of this study was to determine the potential for biosynthesis of propionic acid and vitamin B12 by Propionibacterium freudenreichii T82 in a medium containing various sources of carbon (glucose, fructose, and saccharose). These sugars are present in apple pomaces, which are the waste from the production of apple juice. Using statistical analysis design of experiments (DoE), the results allowed us to determine which sugars (carbon sources) exert the most beneficial influence on the biosynthesis of propionic acid and cobalamin. The highest production of propionic acid by the tested bacterial strain was obtained in a medium in which glucose accounted for at least 50% of the available carbon sources. Depending on the culture medium, the concentration of this metabolite ranged from 23 to 40 g/L. P. freudenreichii T82 produced the smallest amount of acid in medium in which the dominant nutrient source was saccharose. The results obtained indicated an inverse relationship between the amount of acid produced by the bacteria and vitamin B12 biosynthesis. Because of the high efficiency of propionic acid biosynthesis by P. freudenreichii T82, the prospect of using this strain to obtain propionate with the simultaneous disposal of waste materials (such as apple pomaces) which contain glucose and/or fructose is very promising.     

Limitation of usage of PicoGreen dye in quantitative assays of double-stranded DNA in the presence of intercalating compounds

PicoGreen is a very sensitive fluorescent dye for quantitative assays of double-stranded DNA (dsDNA) in solution and is used in several analytical protocols in which sensitive and precise DNA detection is needed, also for examination of drug-DNA interactions. The data shown in this paper indicate that compounds intercalating to DNA influence the applicability of PicoGreen dye for quantitative measurements of dsDNA, and for this reason PicoGreen dye is not suitable for examination of drug-DNA interactions, especially interstrand DNA crosslinks.     

Activity of resveratrol triesters against primary acute lymphoblastic leukemia cells

Resveratrol is a common polyphenol of plant origin known for its cancer prevention and other properties. Its wider application is limited due to poor water solubility, low stability, and weak bioavailability. To overcome these limitations, a series of 13 novel resveratrol triesters were synthesized previously. In this paper, we describe the synthesis of 3 additional derivatives and the activity of all 16 against primary acute lymphoblastic leukemia cells. Of these, 3 compounds were more potent than resveratrol (IC₅₀ = 10.5 µM) namely: resveratryl triacetate (IC₅₀ = 3.4 µM), resveratryl triisobutyrate (IC₅₀ = 5.1 µM), and resveratryl triisovalerate (IC₅₀ = 4.9 µM); all other derivatives had IC₅₀ values of >10 µM. Further studies indicated that the active compounds caused G1 phase arrest, increased expression of p53, and induced characteristics of apoptotic cell death. Moreover, the compounds were only effective in cycling cells, with cells arrested in G1 phase being refractory.     

Interactions Between the Circadian Clock and Heme Oxygenase in the Retina of <Emphasis Type="Italic">Drosophila melanogaster</Emphasis>

The Drosophila retina has an autonomous peripheral circadian clock in which the expression of the gene encoding heme oxygenase (HO) is under circadian control with the ho mRNA peaking at the beginning of the day and in the middle of the night. The function of HO in the retina is unknown, but we observed that it regulates the circadian clock and protects photoreceptors against DNA damage. The decline in HO level increases and decreases the expression of the canonical clock genes period (per) and Clock (Clk), respectively. The opposite result was observed after increasing HO expression. Among three products of HO activity—carbon monoxide (CO), ferrous ions, and biliverdin—the latter has no effect on per and Clk expressions, but CO exerts the same effect as the increase of ho expression. This suggests that HO action on the clock is mediated by CO, which may affect Clk expression during the day and the level of per expression. While ho expression is not stimulated by nitric oxide (NO), NO has the same effect on the clock as HO, increasing Clk expression and decreasing the expression of per.