On the immunological detection of X-ray induced DNA damage

Summary Denatured calf-thymus DNA was X-irradiated, coupled to methylated bovine serum albumin and injected into rabbits to study the possible formation of specific antibodies. The serological activity was tested by a modified Farr-test, a micro complement binding reaction and by caesium chloride isopycnic ultracentrifugation. It was found with all assays that the immunological reaction was mainly due to unspecific DNA-binding and only a very small amount to radiation products. It seems, therefore, that this approach is not suitable for the analytical investigation of DNA damage produced by ionizing radiation.This work is part of the Ph.D. theses of H. Waller and E. Friess (D26, Justus-Liebig-Universität Gießen, FRG)     

Fine structure of the drum muscles of the piranha (serrasalminae,characidae)

Summary The anterior and the posterior drum muscles of the piranha resemble each other in all essential fine structural aspects: myofibrils are slender; sarcomeres are short compared with those of other drum muscles; mitochondria, located in the periphery of the fibers, are numerous and show an irregular internal structure; and the sarcoplasmic reticulum is abundant. Triads appear at the level of the Z lines. The drum muscles have many motor endplates, which, however, lack the characteristic junctional-fold apparatus. No lipid substances could be demonstrated in these muscles. In the posterior drum muscle the fibers depart from their orderly longitudinal arrangement at irregular intervals.     

Simultaneous determination of seven penicillins in muscle, liver and kidney tissues from cattle and pigs by a multiresidue high-performance liquid chromatographic method

A high-performance liquid chromatographic (HPLC) method based on solid-phase extraction (SPE) was developed for determination of amoxicillin, penicillin G (benzylpenicillin), ampicillin, oxacillin, cloxacillin, nafcillin and dicloxacillin in muscle, liver and kidney tissues of pigs and cattle. The compounds were extracted in aqueous solution by precipitation of organic materials with a mixture of sulphuric acid and sodium tungstate. The extract was cleaned up by SPE on a divinylbenzene-co-N-vinylpyrrolidone polymeric sorbent. Further clean-up was performed by liquid–liquid partition with diethyl ether. The extract was derivatised with benzoic anhydride and 1,2,4-triazole mercury (II) reagent. Chromatography was performed by reversed-phase gradient HPLC on a C₁₈ column with ultraviolet detection at 323 nm. The limits of detection estimated by a conservative model were in the range 8.9–11.1 μg/kg for amoxicillin, penicillin G, ampicillin, oxacillin, cloxacillin and nafcillin and 18.3–20.9 μg/kg for dicloxacillin. The mean recovery range was 66–77% for amoxicillin, 73–75% for penicillin G, 81–82% for ampicillin, 73–76% for oxacillin, 74–75% for cloxacillin, 66–72% for nafcillin and 58–65% for dicloxacillin.     

Conflict between Amino Acid and Nucleotide Characters

Slowly evolving characters, such as amino acids and replacement substitutions, have generally been favored over faster evolving characters for inferring phylogenetic relationships. However, amino acids constitute composite characters and, because of the degenerate genetic code, are subject to convergence. Based on an analysis of atpB and rbcL in 567 seed plants, we show that silent substitutions may be more phylogenetically informative than replacement substitutions and that artifacts caused by composite characters and/or convergence cause clades on amino acid trees to conflict with nucleotide trees and independent evidence. These findings indicate that coding nucleotide sequences only as amino acid characters for phylogenetic analysis provides little benefit and may yield misleading results.