An assay for human chorionic gonadotrophin using the capillary fill immunosensor

Recently there has been much research effort directed towards the development of immunosensors. Optical technologies are currently proving very attractive for the construction of such sensors. The fluorescence capillary fill device (FCFD) has been designed to fulfil these needs. The development of an assay for human chorionic gonadotrophin (hCG) in the FCFD for a variety of body fluids (whole blood, serum, urine and saliva) demonstrates the versatility and assay performance of the device.     

Protein ligand interactions. Indole alkaloids as inhibitors for lactate dehydrogenase

Kinetic analysis showed that the indole alkaloids strychnine and brucine interact competitively with the enzyme lactate dehydrogenase with respect to the substrate pyruvate and non competitively with respect to NADH. Since the alkaloids possess a potential enolate and a quaternary nitrogen they bridge the binding sites for the substrates - pyruvate and NAD+. Conformational alterations induced by the binding of ligands to the enzyme subunits are discussed in terms of the proposed chemical model.     

Displacement of soil aggregates by elongating roots and emerging shoots of crop plants

Summary Models are presented in this paper for prediction of the extent to which soil aggregates in a loose seed bed can be displaced by extending roots and shoots. For roots, the maximum applied force is considered to be limited by either elastic bending, when the angle of contact with an aggregate surface is oblique, or buckling, when the root meets an aggregate perpendicularly. For emerging shoots, only the maximum forces are known. These forces are related to the known force displacement behaviour of artificially prepared beds of graded soil aggregates.It is concluded that displacement of soil aggregates which lie between 20 and 100 mm from the surface of the aggregate bed is only likely to be important for roots with diameters of 0.5 mm or less when the diameter of the aggregates in the bed is less than 1 mm. However, for plant species which have relatively large root diameters, such as pea, significant displacement of aggregates of up to 4 mm diameter may be possible. In contrast, emerging shoots are able to displace very much larger aggregates from their paths.     

Long-term effects of ungulates on phytophagous insects

Abstract.  1. Most plants interact with a diverse suite of herbivores, allowing the opportunity for the existence of positive and negative interactions between highly dissimilar organisms. However, most studies on herbivorous interactions have been performed under the assumption that they occur mainly between similar species. Consequently, ecologists are still far from a full understanding of the ecological factors that determine insect population dynamics.
2. In this study, a 7-year field experiment was conducted that manipulated the presence of ungulates to evaluate their effects on the abundance, attack rate, and survival of four guilds of co-occurring herbivorous insects living on the same host plant: seed predators, stem borers, gall makers and sap suckers. These four guilds differed in habits and behaviour, the first three being sessile and endophytic and the last being free-living.
3. This study shows that the abundance of all four guilds was negatively affected by ungulates. However, the effect on attack rate differed among guilds, as mammals do not affect the seed predator attack rate. Ungulates also differentially affected insect survival, ingesting only seed predators and gall makers.
4. In summary, this study suggests that diverse mechanisms may affect different insect guilds in different ways. Therefore, competition between disparate herbivores appears to be complex and can be provoked by multiple mechanisms.     

Antisense RNA decreases AP33 gene expression and cytoadherence by <Emphasis Type="Italic">T. vaginalis</Emphasis>

Background  

Host parasitism by Trichomonas vaginalis is complex. Adherence to vaginal epithelial cells (VECs) is mediated by surface proteins. We showed before that antisense down-regulation of expression of adhesin AP65 decreased amounts of protein, which lowered levels of T. vaginalis adherence to VECs. We now perform antisense down-regulation of expression of the ap33 gene to evaluate and confirm a role for AP33 in adherence by T. vaginalis. We also used an established transfection system for heterologous expression of AP33 in T. foetus as an additional confirmatory approach.     

Revising the Bantu tree

Phylogenetic methods offer a promising advance for the historical study of language and cultural relationships. Applications to date, however, have been hampered by traditional approaches dependent on unfalsifiable authority statements: in this regard, historical linguistics remains in a similar position to evolutionary biology prior to the cladistic revolution. Influential phylogenetic studies of Bantu languages over the last two decades, which provide the foundation for multiple analyses of Bantu sociocultural histories, are a major case in point. Comparative analyses of basic lexica, instead of directly treating written words, use only numerical symbols that express non-replicable authority opinion about underlying relationships. Building on a previous study of Uto-Aztecan, here we analyse Bantu language relationships with methods deriving from DNA sequence optimization algorithms, treating basic vocabulary as sequences of sounds. This yields finer-grained results that indicate major revisions to the Bantu tree, and enables more robust inferences about the history of Bantu language expansion and/or migration throughout sub-Saharan Africa. “Early-split” versus “late-split” hypotheses for East and West Bantu are tested, and overall results are compared to trees based on numerical reductions of vocabulary data. Reconstruction of language histories is more empirically based and robust than with previous methods.