A hybrid dilemma: a molecular investigation of South African bontebok (Damaliscus pygargus pygargus) and blesbok (Damaliscus pygargus phillipsi)

Human-mediated hybridization poses a serious threat to the genetic integrity of threatened inter-fertile species or subspecies, such as the bontebok (Damaliscus pygargus pygargus) and blesbok (Damaliscus pygargus phillipsi) in South Africa. The identification of pure and admixed populations is key to sound biodiversity conservation management and practices. Where identification based on morphometric measurements are complex, molecular analysis can provide a tool to identify hybrids or introgression in populations. This study provides the first molecular analyses on pure bontebok and blesbok as well as putative hybrid populations and samples of unknown purity. Analysis of a panel of 13 microsatellite markers by applying a Bayesian model-based clustering programme provided evidence of clear partitioning between the two subspecies. Hybridization was detected in 33 % (40 of 121) of the samples with unknown purity. Currently, bontebok is listed as protected under the Convention on International Trade in Endangered Species of Wild Fauna and Flora and is listed as endangered under the United States of America’s Endangered Species Act. Our research found that the microsatellite markers used in this study could accurately identify pure and hybrid animals and can be used as a tool to conserve the genetic integrity of both subspecies.     

Localization within the heavy chain sequence of tyrosyl peptides from the combining sites in a rabbit anti-3-azopyridine antibody preparation

A relatively homogeneous rabbit heavy chain was cleaved by CNBr. Fragment C-1 (the N-terminal half of the heavy chain) was isolated. Reduction and alkylation of C-1 liberated three fragments and partial sequence analysis of these isolated fragments showed that C-1 had been split on the carboxyl-side of Met 84. Similar results were obtained with another anti-hapten antibody preparation in which tyrosyl residues in the combining sites had been labeled. The labeled tyrosyl residues were found in the fragment representing residues 85–253. Since the constant region begins at about residue 120 and the sequences of the tyrosyl peptides from the combining sites are not present in published constant region sequences, these peptides appear to be derived from a variable region between residues 85 and 120.     

Effects of acidity on the insoluble polysaccharide content of germinating pollen of Pinus pinea L. and Pinus pinaster Aiton

The PAS reaction was used to stain total insoluble polysaccharides in pollen of two species of Pinus collected in two different years and germinated in vitro at different pH values. PAS-detectable polysaccharides are localized in the intine, cytoplasm and amyloplasts; PAS-undetectable (callose) in the middle of the intine, but only in the distal part of the grain. The total PAS stained polysaccharide content was quantified with a microdensitometer. Values are correlated with germination percentages and pollen tube length. The total polysaccharide content, as well as pollen tube length, varies in each species according to the year, probably due to environmental conditions. Also the various pHs deeply influence pollen germination and tube length, the lowest pH being the most unfavourable condition. At this pH (3.5) the total polysaccharide content is higher than in the control (pH 5.5): this is probably due to a lack of callose synthesis for tube wall or to a depolymerization of this polysaccharide, and a subsequent storage in a PAS-detectable form.     

Sterol composition of some mediterranean green algae

The distribution of sterols in ten Mediterranean green algae has been examined. Clionasterol is typical for the Siphonocladales and all the species of the Siphonales not belonging to the genus Codium, which is characterized by clerosterol. 28-Isofucosterol has been confirmed to be characteristic of the Ulotrichales.