A new species of Polystoma (Monogenea: Polystomatidae) parasitic in Hyperolius marmoratus (Anura: Hyperoliidae) in South Africa

Polystoma marmorati n. sp. is described as a new polystomatid species parasitic in the urinary bladder of the painted reed frog Hyperolius marmoratus marmoratus collected in southern Natal, South Africa. Parasite prevalence varied from 14.5 to 47.4% and the mean intensity from 1.0 to 1.1. The hamuli of the new species have a characteristic, partly fragmented appearance, a feature also seen in Polystoma batchvarivi, the only other polystome described from a species of the genus Hyperolius. The similarity between the two species, in spite of their geographical separation, is commented upon.     

Founder effect in a Belgian-Dutch fragile X population

For many years, the high prevalence of the fragile X syndrome was thought to be caused by a high mutation frequency. The recent isolation of the FMR1 gene and identification of the most prevalent mutation enable a more precise study of the fragile X mutation. As the vast majority of fragile X patients show amplification of an unstable trinucleotide repeat, DNA studies can now trace back the origin of the fragile X mutation. To date, de novo mutations leading to amplification of the CGG repeat have not yet been detected. Recently, linkage disequilibrium was found in the Australian and US populations between the fragile X mutation and adjacent polymorphic markers, suggesting a founder effect of the fragile X mutation. We present here a molecular study of Belgian and Dutch fragile X families. No de novo mutations could be found in 54 of these families. Moreover, we found significant (P < 0.0001) linkage disequilibrium in 68 unrelated fragile X patients between the fragile X mutation and an adjacent polymorphic microsatellite at DXS548. This suggests that a founder effect of the fragile X mutation also exists in the Belgian and Dutch populations. Both the absence of new mutations and the presence of linkage disequilibrium suggest that a few ancestral mutations are responsible for most of the patients with fragile X syndrome.     

Influence of plant domestication on plant-pollinator interactions: Floral attributes and floral visitor communities in wild and cultivated squash plants

Premise

Domestication of plant species results in phenotypic modifications and changes in biotic interactions. Most studies have compared antagonistic plant-herbivore interactions of domesticated plants and their wild relatives, but little attention has been given to how domestication influences plant-pollinator interactions. Floral attributes and interactions of floral visitors were compared between sister taxa of the genus Cucurbita (Cucurbitaceae), the domesticated C. moschata, C. argyrosperma ssp. argyrosperma and its wild progenitor C. argyrosperma ssp. sororia in the place of origin.

Methods

We conducted univariate and multivariate analyses to compare floral morphological traits and analyzed floral reward (nectar and pollen) quantity and quality between flowers of wild and domesticated Cucurbita taxa. Staminate and pistillate flowers of all three taxa were video recorded, and visitation and behavior of floral visitors were registered and analyzed.

Results

Most floral morphological characteristics of flowers of domesticated taxa were larger in both staminate and pistillate flowers. Staminate and pistillate flowers presented distinct correlations between floral traits and integration indices between domesticated and wild species. Additionally, pollen quantity and protein to lipid ratio were greater in domesticated species. Cucurbit pollen specialists, Eucera spp., had the highest probability of visit for all Cucurbita taxa.

Conclusions

We provide evidence that floral traits of domesticated and wild Cucurbita species experienced different selection pressures. Domesticated Cucurbita species may have more resources invested towards floral traits, thereby increasing attractiveness to pollinators and potentially plant reproductive success. Wild ancestor plant populations should be conserved in their centers of origin to preserve plant-pollinator interactions.     

Stereoselectivity in β-cyclodextrin complexation of 1,4-dihydropyridine derivatives

Structure–interaction relationships, stereoselectivity, and solubility enhancement in inclusion compexation of β-cyclodextrins (CDs) with some racemic and enantiomerically pure 1,4-dihydropyridine derivatives (DHPs) were investigated. 1:1 and 1:2 (mole ratio) complexes were prepared and characterized by X-ray powder diffraction, differential scanning calorimetry (DSC), MS-FAB spectrometry, ¹H-NMR spectroscopy, water and phase solubility. The solubility studies have revealed different complexation equilibria for optically pure DHP enantiomers, and corresponding racemic mixtures in water solutions. By means of ¹H-NMR chemical shift measurements, the inclusion of aromatic fragments of racemic and enantiomerically pure DHP molecules within the cavities of different CDs was elucidated. Considerable stereoselectivity in complexation interactions was observed. The results indicate the potential use of cyclodextrins as chiral selectors for enantiomeric resolution of 1,4-DHP calcium antagonists. © 1993 Wiley-Liss, Inc.     

Complementation studies with the gas vesicle-encoding p-vac region of Halobacterium salinarium PHH1 reveal a regulatory role for the p-gvpDE genes

Gas-vesicle (Vac) synthesis in Halobacterium salinarium PHH1 involves the expression of the p-vac region consisting of 14 different gvp genes that are arranged in two clusters: p-gvpACNO and, oppositely oriented, p-gvpDEFGHIJKLM. The latter cluster of genes is transcribed as two units: p-gvpDE and p-gvpF–M. The 5′-terminus of the p-gvpF–M mRMA was located 169 nucleotides upstream of p-gvpF within p-gvpE. The p-gvpG and p-gvpK gene was expressed in Escherichia coli and antibodies to proteins obtained were raised in rabbits. Both proteins could be detected in halobacterial cell lysates; in gas-vesicle preparations, however, neither GvpG nor GvpK could be found. The requirement for single p-gvp gene expression for gas-vesicle synthesis was determined by transformation experiments using the Vac^? species Haloferax volcanii as recipient. Construct ΔA containing all p-gvp genes except for p-gvpA, encoding the major gas-vesicle structural protein, produced Vac^? transformants, but the addition of p-gvpA on a second vector restored gas-vesicle synthesis to wild-type level (Vac⁺⁺). Similarly, double transformants containing p-gvpD–M plus p-gvpACNO, or p-gvpG–M (fused to the promoter of the halobacterial ferredoxin gene for expression) plus p-gvpFED–ACNO were Vac⁺⁺. Transformants containing the p-vac region either lacking gvpA, gvpF, or gvpGHI were Vac^?, indicating the absolute requirement of these gvp genes (or at least one in the case of gvpGHI) for gas-vesicle formation. Double transformants containing the constructs p-gvpF–M plus p-gvpACNO (ΔDE) accumulated gas vesicles (Vac⁺) but synthesized fewer than the wild type, showing that the p-gvpDE genes are not necessary for gas-vesicle assembly. A repressor function affecting the synthesis of the p-gvpF–M mRNA could be suggested for p-gvpD and the 5′- region of its mRNA.     

Cocultivation studies with cells of patients bearing fragile X chromosomes

Summary Fourteen cocultivation studies were carried out with cells of four patients with fragile X, one obligate and two possible female heterozygotes, two female controls, and a rabbit. In all cocultivations the number of fragile X chromosomes was sharply reduced in the patient cells. The strongest effect was caused by the animal cells. A distinct difference between the two controls in the reducing ability was observed. No such difference was found between the obligate and possible heterozygotes on the one hand and the controls on the other. To test the influence of the residual serum in the mixed blood cultures, the serum of a patient's blood sample was replaced by the serum of a control. The frequency of fragile X chromosomes was not decreased by this procedure. Therefore a soluble factor is supposed to exist which is produced by normal or heterozygote cells in culture and which reduces the expression of fragile sites in patient cells.     

gA and gB glycoproteins of herpes simplex virus type 1: two forms of a single polypeptide.

Utilizing a combination of preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis and sodium dodecyl sulfate-hydroxylapatite column chromatography, we have separated and purified the gA and gB glycoproteins of the major virus-specific glycoprotein region from herpes simplex virus type 1-infected cells. By using purified antigen preparations, antisera specific to each of these glycoproteins were produced. Immunoprecipitation from detergent extracts of infected cells and radioimmune precipitation of the purified antigens have shown that the anti-gA and anti-gB sera each recognize both the gA and the gB glycoproteins. The anti-gA serum was also shown to neutralize virus despite the presence of only minute quantities of the gA glycoprotein in virions. Pulse-chase studies have indicated that the gA and gB glycoproteins are synthesized from a common precursor polypeptide. Together, these data demonstrate that the gA and gB glycoproteins of herpes simplex virus type 1 are antigenically similar but not identical and probably represent two different forms of the same polypeptide which differ in their degree of glycosylation.     

High-performance liquid chromatographic analysis of neutral glycosphingolipids as their per-O-benzoyl derivatives

Previous reports from this laboratory (1–4) described the perbenzoylation of neutral glycosphingolipids (GSL)¹ with benzoyl chloride in pyridine and analysis of the perbenzoylated derivatives by high performance liquid chromatography (hplc). A disadvantage of this procedure is that N-benzoylation occurs as well as the desired O-benzoylation. This does not permit recovery of the parent GSL after mild alkaline hydrolysis due to formation of a mixture of N-acylated and N-benzoylated GSLs(1). It has also been demonstrated that the benzoylation with benzoic anhydride in pyridine does not lead to the formation of N-benzoylated products. However, the anhydride reaction is sluggish and the benzoyl chloride method has been the preferred procedure.Gupta et al. (5) used N,N-dimethyl-4 amino pyridine (DMAP) as a catalyst in the acylation of phospholipids by the anhydrides of fatty acids. F. B. Jungalwala (private communication) has shown that this catalyst greatly accelerates the reaction of benzoic anhydride with sulfatides.In this communication we report the preparation and hplc analysis of per-O-benzoyl derivatives of GSLs by reaction with benzoic acid anhydride in the presence of DMAP as a catalyst. Reaction with these reagents avoids amide acylation, forms single products with satisfactory chromatographic properties and parent GSLs can be regenerated by mild alkaline hydrolysis.