In vitro poly(ADP-ribosyl)ation of seminal ribonuclease

The site of in vitro ADP-ribosylation of seminal ribonuclease was determined. Seminal enzyme was found to be a good receptor of [14C]ADP-ribose residues under the reaction conditions used. The recovery of [14C]ADP-ribosylated RNase was about 65% after purification. After tryptic digestion of modified enzyme, a fraction containing [14C]ADP-ribosylated peptides was separated from the others by ion-exchange chromatography on M82 resin. Radioactive peptides were then purified by affinity chromatography on anti-poly(ADP-ribose)IgG-Sepharose. High performance liquid chromatography of a mixture obtained after pronase digestion of purified ADP-ribosylated peptides revealed only one radioactive peptide whose amino acid composition corresponded to a peptide that has equimolar quantities of aspartic acid, serine, and glycine. Carboxypeptidase Y digestion of this peptide showed that its amino acid sequence was Asp-Ser-Gly. Only position 14-16 of seminal RNase corresponded to this sequence. The chemical stability of the ADP-ribose/enzyme linkage indicated that aspartic acid 14 is the modification site in seminal RNase.     

Configuration and optimization of a common two-site immunoassay for human prolactin using a chemiluminescent tracer and an enzymatic tracer

We have developed a two-site immunoassay for human prolactin using two monoclonal antibodies: one of them immobilized on the solid phase and the other labelled with biotin. The serum is incubated simultaneously with the antibody-coated bead, the biotinylated antibody and the tracer (streptavidin–isoluminol or avidin–peroxidase complex). Our experimental work has been directed towards a common set of reagents to capture the prolactin and then, with different tracers, towards obtaining on the calibration curve the same results for unknown samples. On the basis of the positive results we obtained, we have developed a kit that can be used by the customer or as an enzyme-immunoassay or as a chemiluminescent immunoassay, depending on instrumentation available, spectrophotometer or luminometer.     

Subject: Adaptation

Research Notes on Avian Biology 1994: Selected Contributions from the 21st International Ornithological CongressSystematics and Evolution of Birds: Adaptation

Subject: Adaptation     

Phylogeny of Greya (Lepidoptera: Prodoxidae), based on nucleotide sequence variation in mitochondrial cytochrome oxidase I and II: congruence with morphological data

The phylogeny of Greya Busck (Lepidoptera: Prodoxidae) was inferred from nucleotide sequence variation across a 765-bp region in the cytochrome oxidase I and II genes of the mitochondrial genome. Most parsimonious relationships of 25 haplotypes from 16 Greya species and two outgroup genera (Tetragma and Prodoxus) showed substantial congruence with the species relationships indicated by morphological variation. Differences between mitochondrial and morphological trees were found primarily in the positions of two species, G. variabilis and G. pectinifera, and in the branching order of the three major species groups in the genus. Conflicts between the data sets were examined by comparing levels of homoplasy in characters supporting alternative hypotheses. The phylogeny of Greya species suggests that host-plant association at the family level and larval feeding mode are conservative characters. Transition/transversion ratios estimated by reconstruction of nucleotide substitutions on the phylogeny had a range of 2.0-9.3, when different subsets of the phylogeny were used. The decline of this ratio with the increase in maximum sequence divergence among taxa indicates that transitions are masked by transversions along deeper internodes or long branches of the phylogeny. Among transitions, substitutions of A-->G and T-->C outnumbered their reciprocal substitutions by 2-6 times, presumably because of the approximately 4:1 (77%) A+T-bias in nucleotide base composition. Of all transversions, 73%-80% were A<-->T substitutions, 85% of which occurred at third positions of codons; these estimates did not decrease with an increase in maximum sequence divergence of taxa included in the analysis. The high frequency of A<-->T substitutions is either a reflection or an explanation of the 92% A+T bias at third codon positions.