The malmö polymorphism of coagulation factor IX, an immunologic polymorphism due to dimorphism of residue 148 that is in linkage disequilibrium with two other F.IX polymorphisms

A mouse monoclonal antibody (MAB 9.9) to coagulation factor IX (F.IX) detects a polymorphism in the plasma of normal people. Its epitope has been narrowed down to <6 amino acids in the activation peptide of the X-linked F.IX protein. The activation peptide contains a dimorphism—Thr:Ala—at position 148 of the protein. Using synthetic oligonucleotides, we have demonstrated that (1) the F.IX which reacts with 9.9 has Thr at position 148 and (2) that which does not has Ala. Positive reactors (148^thr) are designated Malmö A, and negative reactors (148^ala) are designated Malmö B. The plasma levels of AA women are indistinguishable from those of A men, and both B men and BB women are null against MAB 9.9. The plasma level of Malmö A in AB women is approximately half that of AA women, and “lyonization” is clearly operating in the heterozygotes. The dimorphism is in strong linkage disequilibrium with two other intragenic RFLPs, TaqI and XmnI. Furthermore, intragenic crossing-over—including double crossing-over—appears to have occurred between the three sites. Seven of the eight possible haplotypes have been identified, five in men and two others in women. The immunoassay that identifies ～50% of the AB women in the pool of Malmö A females with 95% confidence identifies men unambiguously as A or B. The assay would be very useful for population-genetic studies of the Malmö epitope if the studies were limited to men.     

Opa-like repeats in the genome of the Medfly Ceratitis capitata

The sequence determination of several genomic clones isolated from the Mediterranean fruitfly Ceratitis capitata identified the existence of opa-like repeats, often more than one being clustered in small chromosomal segments. These repeats have previously been shown to consist of stretches of tandemly reiterated glutamine-encoding residues, and they are found in multiple genes of several organisms. Most of the repeats described here are flanked or interrupted by stop codons in all reading frames and, thus, could not possibly be part of protein-coding sequences. Furthermore, these repeats, of which there are several hundred in the genome of the Medfly, can be used effectively for the determination of sequence polymorphisms, providing a convenient approach to obtain additional landmarks for the construction of genomic maps of this economically important insect.This paper is dedicated to the memory of our colleague and friend Dr. Jim Flach who took part in the initial phase of this work and died during the course of the investigation.     

Evaluation of the use of cyclodextrins in chiral separation of basic drug substances by capillary electrophoresis

The influence of the choice of type and/or concentration of cyclodextrin, other additives, the temperature surrounding the capillary, and buffer pH on the separation of some chiral basic drug substances in capillary zone electrophoresis has been evaluated. It was found that pH of the buffer and type and concentration of cyclodextrin had a major influence on the separation. © 1995 Wiley-Liss, Inc.     

Polyol accumulation by two filamentous fungi grown at different concentrations of NaCl

The accumulation of polyols by Aspergillus niger (van Tiegh) strain S 1 and Penicillium chrysogenum (Thom) strain S 30 was followed during growth in media of different concentrations of NaCl. The major polyols found were glycerol, erythritol and mannitol. The total polyol pool increased in both organisms in response to raised salinity, and the proportion of glycerol and erythritol was markedly enhanced at high salinity.     

Multi-system approach to study mutagenesis induced by chemical carcinogens.

To understand molecular mechanisms of the mutation fixation process induced by a mutagen and carcinogen, a multi-system approach is suggested to reduce the probability that the results are biased by the assay used. In this light we described our different approaches to answer basic questions on the mutagenesis induced by the chemical carcinogen 4-Nitroquinoline-1-oxide. We determined mutations at the molecular level in three experimental systems: a) in prokaryotes (ss M13mp19 lacZ'/E. coli F'lacZ delta M15); b) in eukaryotes (i) ss and ds pZ189 supF/CV1-P/E.coli lacZam and (ii) HPRT in CHO cells with different repair capacity. We think this type of approach can be used to study the genetic effects of new cancer drugs for which the molecular mechanisms of action at the molecular level are still not well understood. We think to apply the know-how to study mutational spectra in tumor derived tumor suppressor genes.     

A perforin‐like protein mediates disruption of the erythrocyte membrane during egress of Plasmodium berghei male gametocytes

Successful gametogenesis of the malaria parasite depends on egress of the gametocytes from the erythrocytes within which they developed. Egress entails rupture of both the parasitophorous vacuole membrane and the erythrocyte plasma membrane, and precedes the formation of the motile flagellated male gametes in a process called exflagellation. We show here that egress of the male gametocyte depends on the function of a perforin‐like protein, PPLP2. A mutant of Plasmodium berghei lacking PPLP2 displayed abnormal exflagellation; instead of each male gametocyte forming eight flagellated gametes, it produced gametocytes with only one, shared thicker flagellum. Using immunofluorescence and transmission electron microscopy analysis, and phenotype rescue with saponin or a pore‐forming toxin, we conclude that rupture of the erythrocyte membraneis blocked in the mutant. The parasitophorous vacuole membrane, on the other hand, is ruptured normally. Some mutant parasites are still able to develop in the mosquito, possibly because the vigorous motility of the flagellated gametes eventually leads to escape from the persisting erythrocyte membrane. This is the first example of a perforin‐like protein in Plasmodium parasites having a role in egress from the host cell and the first parasite protein shown to be specifically required for erythrocyte membrane disruption during egress.     

Enhanced N-metabolites,ABA and IAA-conjugate in anthers instigate heat sensitivity in spring wheat

Unraveling the metabolic and phytohormonal changes in anthers exposed to heat stress would help identify mechanisms regulating heat stress tolerance during the sensitive reproductive stage. Two spring wheat genotypes contrasting for heat tolerance were exposed to heat stress during heading in controlled environment chambers. Anthers were collected from main and primary spikes for metabolic and phytohormonal profiling. A significant reduction in seed set (38%), grain number (54%) and grain weight (52%) per plant was recorded in the sensitive (KSG1177) but not in the tolerant (KSG1214) genotype under heat stress compared to control. Anther metabolite accumulation did not vary quantitatively between main and primary spikes. Hierarchical clustering of the genotypes and treatments using metabolites and phytohormones revealed a distinct cluster for KSG1177 under heat stress from that of control and KSG1214. A significant increase in N-based amino acids, ABA, IAA-conjugate and a decrease in polyamines and organic acids were observed in wheat anthers exposed to heat stress. Unlike KSG1214, a significantly higher accumulation of amino acids, ABA and IAA-conjugate in anthers of the sensitive KSG1177 was recorded under heat stress. These findings provide the rationale and direction towards developing molecular markers for enhancing heat stress tolerance in wheat.