ABSTRACT
A well-known link exists between an organism's ecology and morphology. In the European eel, a dimorphic head has been linked to differences in feeding ecology, with broad-headed eels consuming harder prey items than narrow-headed ones. Consequently, we hypothesized that broad-heads should exhibit a cranial musculoskeletal system that increases bite force and facilitates the consumption of harder prey. Using 3D-reconstructions and a bite model, we tested this hypothesis in two life stages: the sub-adult yellow eel stage and its predecessor, the elver eel stage. This allowed us to test whether broad- and narrow-headed phenotypes show similar trait differences in both life stages and whether the dimorphism becomes more pronounced during ontogeny. We show that broad-headed eels in both stages have larger jaw muscles and a taller coronoid, which are associated with higher bite forces. This increased bite force together with the elongated upper and lower jaws in broad-headed eels can also improve grip during spinning behavior, which is used to manipulate hard prey. Head shape variation in European eel is therefore associated with musculoskeletal variation that can be linked to feeding ecology. However, although differences in muscle volume become more pronounced during ontogeny, this was not the case for skeletal features.
ABSTRACT
The goal of this project was to find and collect high concentrations of endotoxin-specific antibodies for therapeutic IgG- or IgM-enriched preparations. Various enzyme-linked immunosorbent assays (ELISAs) were developed to perform longitudinal studies of the serological response to a large panel of smooth and rough purified lipopolysaccharide (LPS) extracts in a population of healthy blood donors. To accomplish this, 1612 human serum samples from volunteer blood donors collected by seven different blood banks in Belgium were screened and specific IgM and IgG activities were measured. Approximately 17% of the donors had anti-LPS concentrations higher than 40 mg L-1. Of these, 10.9% had anti-smooth LPS antibodies, 3.7% had anti-rough LPS antibodies and 2.8% were found to be positive towards both types of LPS. The mean anti-LPS antibody concentration was 8 mg L-1 for rough LPS and 14 mg L-1 for smooth LPS. Age- and sex-related distributions of the activities indicated that the greatest prevalence of high anti-LPS concentration was in women aged 40-49 years and in men older than 60 years. Differential absorption experiments showed that the pooled serum of selected blood donors contained a mixture of specific and cross-reacting antibodies. We detected predominantly anti-LPS activities due to the IgG1 and IgG2 subclasses. The range of specificities to different LPS was increased by the pooling of selected sera. It was concluded that pools of naturally occurring specific anti-LPS immunoglobulin antibodies may be obtained in Belgium by screening blood donors using ELISAs that we have developed.
