The natural chlorine cycle - Formation of the carcinogenic and greenhouse gas compound chloroform in drinking water reservoirs.

Chlorine cycle in natural ecosystems involves formation of low and high molecular weight organic compounds of living organisms, soil organic matter and atmospherically deposited chloride. Chloroform (CHCl3) and adsorbable organohalogens (AOX) are part of the chlorine cycle. We attempted to characterize the dynamical changes in the levels of total organic carbon (TOC), AOX, chlorine and CHCl3 in a drinking water reservoir and in its tributaries, mainly at its spring, and attempt to relate the presence of AOX and CHCl3 with meteorological, chemical or biological factors.

A new approach for cytokinin isolation from Arabidopsis tissues using miniaturized purification: pipette tip solid-phase extraction.

Background: We have developed a new analytical approach for isolation and quantification of cytokinins (CK) in minute amounts of fresh plant material, which combines a simple one-step purification with ultra-high performance liquid chromatography-fast scanning tandem mass spectrometry.

Results: Plant tissue samples (1-5 mg FW) were purified by stop-and-go-microextraction (StageTip purification), which previously has only been applied for clean-up and pre-concentration of peptides. We found that a combination of two reverse phases and one cation-exchange phase, was the best tool, giving a total extraction recovery higher than 80%.

Oostatic peptides containing D-amino acids: synthesis, oostatic activity, degradation, accumulation in ovaries and NMR study.

Analogs of the H-Tyr-Asp-Pro-Ala-Pro-OH pentapeptide with D-amino acid residues either in differing or in all of the positions of the sequences were prepared and their oostatic potency was compared with that of the parent pentapeptide. The D-amino acid residue containing analogs exhibited an equal or even higher oostatic effect in the flesh fly Neobellieria bullata than the parent peptide. Contrary to the rapid incorporation of radioactivity from the labeled H-Tyr-Asp-[3H]Pro-Ala-Pro-OH pentapeptide into the ovaries of N.

Study of oostatic peptide uptake and metabolism in developing ovaries of the flesh fly, Neobellieria bullata.

The uptake and metabolism of the oostatic pentapeptide analogue of trypsin modulating oostatic factor (TMOF), H-Tyr-Asp-Pro-Ala-Pro-OH (5P), in ovaries of Neobellieria bullata (Parker) (Diptera: Sarcophagidae) were analyzed during their developmental stages. During selected stages of yolk deposition, the fate of [3HPro(3)]5P after its in vivo injection was compared to its uptake after in vitro incubation of dissected ovaries. The ovaries were analyzed from 30 s to 180 min after incubation.

Radiochromatographic assay of metabolites of the oostatic peptide labeled in different positions of the peptide chain.

Reversed-phase high-performance liquid radio-chromatography (radio-HPLC) was set up to detect the time course of labeled degradation product formation of the pentapeptide H-Tyr-Asp-Pro-Ala-Pro-OH (5P), which has oostatic effects in different insect species. The detection limit of the system was in the range of 80-150 Bq. To follow formation of the degradation products, three amino acid residues in 5P were independently tritiated: Tyr1, Pro3 and Pro5.

Activity and mechanism of action of insect oostatic peptides in flesh fly.

The relationship between structure and activity of insect oostatic decapeptide (Aed-TMOF) analogues in flesh fly was analyzed. The highest oostatic activity was exhibited by the pentapetide and tetrapeptide analogues, H-Tyr-Asp-Pro-Ala-Pro-OH and H-Tyr-Asp-Pro-Ala-OH, respectively. The tetrapeptide, either native or tritiated, was used to study its metabolism in the ovaries and hemolymph and to detect putative binding sites in the flesh fly ovaries and head.