Host-specific cues cause differential attractiveness of Kenyan men to the African malaria vector Anopheles gambiae

Background  

Many studies have suggested that variability in the attractiveness of humans to host-seeking mosquitoes is caused by differences in the make-up of body emanations, and olfactory signals in particular. Most investigations have either been laboratory-based, utilising odour obtained from sections of the body, or have been done in the field with sampling methods that do not discriminate between visual, physical and chemical cues of the host. Accordingly, evidence for differential attractiveness based on body emanations remains sparse in spite of the far-reaching epidemiological implications of this phenomenon.     

Testosterone, early experience and behavioral arousal in a novel environment

Rhode Island Red chicks were hatched either in isolation or in pairs. On the second day after hatching they were injected with either 0, 0.5, 1.5, 4.5, or 13.5 mg of testosterone. Two days later their emotional response to a novel environment was determined by counting the cheeping rate. It was found that, while low doses of testosterone elevated cheeping, the highest doses caused a depression back to, or below, control levels. The rearing environment also had an effect in that the isolated chicks cheeped more than their social counterparts for every dose except the 0.5-mg dose. It was concluded that testosterone can influence behavioral arousal in chicks but that the effect is dependent upon both dose and previous environmental experience.     

Long-term Effects of Imprinting Exposure upon Breed Discriminatory Behaviour in Chickens

In zwei Experimenten wurde die Wirkung früher Erfahrung mit Ziehgeschwistern auf die spätere Partnerbevorzugung an Haushühnern untersucht.

• 1 Eintagsküken der Rassen Rhode Island Red (RIR) und Australorp wurden in vier verschiedenen Kombinationen 48 Stunden lang gehalten und danach bis zur Geschlechtsreife miteinander aufgezogen. ♂♂, die zwei Küken der eigenen Rasse ausgesetzt worden waren, richteten in den ersten 6—11 Wochen mehr Angriffe auf Rassegenossen als anders behandelte Tiere. Später zeigten sich keine Auswirkungen mehr.
• 2 Ebenso vorbehandelte RIR-♂♂ wurden nur mit Rassegenossen aufgezogen. Hier zeigte sich später eine Prägungswirkung auf die sexuelle Partnerwahl. Die Rassenmischung im ersten Experiment kann also für die da beobachtete geringere Prägewirkung verantwortlich sein. Es gibt Anzeichen dafür, daß eine genetische Rassebevorzugung während der Prägezeit wirkt.

     

Determination of the Lumped Constant for the α-Methyltryptophan Method of Estimating the Rate of Serotonin Synthesis

Abstract: The lumped constant (LC) for the α-methyl-l -tryptophan method to convert the brain's uptake of labeled α-methyl-l -tryptophan into the regional rate of serotonin synthesis was estimated. The method involved independently estimating the unidirectional uptake constant of the tracer (α-[¹⁴C]methyl-l -tryptophan) to the tissue and the tracee (tryptophan) (with the addition of a radioactive compound) and calculating their ratio. The LC was estimated from logarithmically transformed data. Similar experiments were performed using rats treated with the drug probenecid, which blocks the efflux of 5-hydroxyindoleacetic acid (a metabolite of serotonin) from the brain. The experiments using probenecid, corrected for the difference in the levels of plasma free tryptophan (increased in probenecid-treated rats) relative to control experiments, gave an average LC for the rat brain of 0.46 ± 0.14 (mean ± SD). This value was not significantly different from the one obtained in controls (0.43 ± 0.13). In addition, the LC was also calculated using unidirectional uptake constants in the probenecid-treated rats for α-methyl-l -tryptophan and l -tryptophan. This LC value was 0.39 ± 0.10. There was no significant difference between these three LC values. Thus, an average ± SD LC of 0.42 ± 0.07 for 28 brain structures investigated in this study was obtained. Statistically the LC obtained in different structures had a variability that could be accounted for by errors in measurements alone. In other words, dispersion in the LC values could be fully accounted for by chance alone. Data confirmed that the LC value did not change when the rate of serotonin synthesis was increased by probenecid treatment. We also showed that the rate of 5-hydroxyindoleacetic acid accumulation in probenecid-treated rats was 58 pmol g^?1 min^?1 (rat brain), which is about twice as much as reported by others for a normal rat. This difference could also be accounted for by the increase in the plasma level of free tryptophan in probenecid-treated rats.     

Assessing changes in subjective and objective function from pre- to post-knee arthroplasty using the Cardiff Dempster–Shafer theory classifier

The purpose of this study is to assess changes in subjective and objective function from pre- to post-knee arthroplasty (KA) using a combined classifier technique. Twenty healthy adults (50–80 years) and 31 KA patients (39–81 years) were studied (4 weeks pre- and 6 months post-KA). Questionnaire measures of subjective pain, joint stability, activity and function were collected. Objective functional assessment included goniometry, ultrasound imaging and 3-D motion analysis/inverse modelling of gait and sit–stand. An optimal set of variables were used to classify function using the Cardiff Dempster–Shafer theory (DST) method. Out of sample accuracy of the classifiers ranged between 90% and 94% for segregating healthy individuals and pre-KA patients. Post-KA subjective function improved with 74% classified as healthy. However, there was minimal improvement in objective measures (23% classified as healthy). The novel use of Cardiff DST segregated KA patients from healthy individuals and estimated changes in function from pre- to post-surgery. KA patients had improved pain and function post-operation but objective knee joint measures remained different to healthy individuals.     

CASSIOPE: An expert system for conserved regions searches

Background  

Understanding genome evolution provides insight into biological mechanisms. For many years comparative genomics and analysis of conserved chromosomal regions have helped to unravel the mechanisms involved in genome evolution and their implications for the study of biological systems. Detection of conserved regions (descending from a common ancestor) not only helps clarify genome evolution but also makes it possible to identify quantitative trait loci (QTLs) and investigate gene function.     

Conceptual framework and rationale

The sterile insect technique (SIT) has been shown to be an effective and sustainable genetic approach to control populations of selected major pest insects, when part of area-wide integrated pest management (AW-IPM) programmes. The technique introduces genetic sterility in females of the target population in the field following their mating with released sterile males. This process results in population reduction or elimination via embryo lethality caused by dominant lethal mutations induced in sperm of the released males. In the past, several field trials have been carried out for mosquitoes with varying degrees of success. New technology and experience gained with other species of insect pests has encouraged a reassessment of the use of the sterility principle as part of integrated control of malaria vectors. Significant technical and logistic hurdles will need to be overcome to develop the technology and make it effective to suppress selected vector populations, and its application will probably be limited to specific ecological situations. Using sterile males to control mosquito vector populations can only be effective as part of an AW-IPM programme. The area-wide concept entails the targeting of the total mosquito population within a defined area. It requires, therefore, a thorough understanding of the target pest population biology especially as regards mating behaviour, population dynamics, dispersal and level of reproductive isolation. The key challenges for success are: 1) devising methods to monitor vector populations and measuring competitiveness of sterile males in the field, 2) designing mass rearing, sterilization and release strategies that maintain competitiveness of the sterile male mosquitoes, 3) developing methods to separate sexes in order to release only male mosquitoes and 4) adapting suppression measures and release rates to take into account the high reproductive rate of mosquitoes. Finally, success in area-wide implementation in the field can only be achieved if close attention is paid to political, socio-economic and environmental sensitivities and an efficient management organization is established taking into account the interests of all potential stakeholders of an AW-IPM programme.