Prospects for estimating nucleotide divergence with RAPDs

The technique of random amplification of polymorphic DNA (RAPD), which is simply polymerase chain reaction (PCR) amplification of genomic DNA by a single short oligonucleotide primer, produces complex patterns of anonymous polymorphic DNA fragments. The information provided by these banding patterns has proved to be of great utility for mapping and for verification of identity of bacterial strains. Here we consider whether the degree of similarity of the banding patterns can be used to estimate nucleotide diversity and nucleotide divergence. With haploid data, fragments generated by RAPD-PCR can be treated in a fashion very similar to that for restriction-fragment data. Amplification of diploid samples, on the other hand, requires consideration of the fact that presence of a band is dominant to absence of the band. After describing a method for estimating nucleotide divergence on the basis of diploid samples, we summarize the restrictions and criteria that must be met when RAPD data are used for estimating population genetic parameters.     

Enzymic degradation of sorghum glucuronoarabinoxylans leading to tentative structures

Three glucuronoarabinoxylan (GAX) populations, obtained from water-unextractable cell wall material from sorghum by different alkali extractants, were digested by combinations of endo-xylanases (Xyl I, Xyl III and GXH), arabinofuranosidases (AXH and AraB) and an alpha-glucuronidase (GlcAase). All three GAX populations were shown to be rather poorly degradable, due to the very high degree of substitution, as well as the substitution pattern. The barium hydroxide-extracted GAX showed a maximum degree of degradation of almost 12%, using Xyl I combined with GXH and AXH. The GAX population extracted by 4 M KOH was hardly degraded by any of the tested combinations. In all cases, Xyl III showed lowest activity upon the three extracts. Synergistic effects were observed between Xyl I and AXH. Both neutral and acidic arabinoxylan oligomers were formed. The GlcAase acted only upon oligomeric material released by Xyl I. No synergistic effects were observed between the GXH and AXH. Combining the patterns of degradation with the modes of action of the enzymes, structures were proposed for the different populations of sorghum GAX. Evidence was obtained that the xylan backbone of especially the GAX extracted by 4 M KOH, is substituted by arabinose and glucuronic acid according to a strict pattern, which hinders the enzymes to act.     

Conservation of baculovirus inhibitor of apoptosis repeat proteins (BIRPs) in viruses, nematodes, vertebrates and yeasts

The purpose of this study was to compare striatal D2 dopamine receptor occupancy of various typical neuroleptics and clozapine in relation to the occurrence of extrapyramidal side effects (EPS). Forty-four inpatients with schizophrenia, including 12 patients with schizodominant schizoaffective disorder, were evaluated using 123I-iodobenzamide (IBZM) and single photon emission computed tomography. Striatal D2 dopamine receptor occupancy was estimated by use of a striatal/frontal cortex ratio (ST/FC) of IBZM binding. Fourteen patients were neuroleptic-free and served as controls. Six patients were treated with clozapine and 24 patients were treated with various typical neuroleptics. ST/FC ratios in patients taking typical neuroleptics were significantly lower than those who were neuroleptic free or treated with clozapine. Patients with EPS had lower ST/FC ratios than those without EPS. A significant linear relationship between ST/FC ratios and severity of EPS estimated by the Simpson-Angus-Scale was established (r=-0.51, p=0.041).