Domir De Bakker

Plans for a large regional forest in eastern Flanders (Belgium): assessment of spider diversity and community structure in the current forest remnants

The absence of large forests and the importance of natural elements for the welfare and health of people, made the Flemish government and the province of eastern Flanders, Belgium, investigate the establishment of one large regional forest out of existing forest remnants. After several studies, the location ‘Makegem forests–Aelmoeseneiebos’ was withheld for future forest expansion. In this study, the spider fauna of five forest remnants from that region was sampled and differences and congruencies in spider diversity and community structure of these fragments were assessed. Our results show that (1) considering the limited forest areas and high degree of fragmentation, the overall observed spider diversity was high, but half of the spiders were non-forest species, (2) half of the encountered Red list species were restricted to only one of the studied woodlands and creating one large forest may be vital for their conservation, (3) diversity–rarefaction curves were higher for the more humid than for the dryer forest sites, and (4) dissimilarities between spider communities are mostly caused by historical factors and humidity and are therefore also linked with the properties of the litter layer and main tree species. We conclude that an expansion of the existing forest remnants will likely maintain or even improve the richness of the spider faunas. Because sufficiently large suitable habitats will develop, several (critical) species may be saved. This is, however, only possible if the characteristic properties of the forests are preserved.

A spider silk supportive matrix used for cartilage regeneration

Injured cartilage, not accreting by itself, often decreases the quality of life. The chondrocytes need an implanted support to bridge and recover the wound with extracellular matrix products forming fresh cartilage. Advances in cell biology and biomaterial research have lead to new possibilities in tissue engineering. Transplanted scaffolds, holding a 3D cell culture, should copy the cartilage characteristics. Strength and flexibility are important, but even more an adequate porosity, so the chondrocytes can migrate through the matrix, but are not able to float around. Looking for regeneration and not a repair, we want the scaffold material to disappear while real cartilage is healing the wound. In this way the material and its hydrolysis products have to be biocompatible and harmless. In the case of synthetic polymers, the hydrolysis products are frequently toxic, Spider silk is a promising fibre for many applications. Completely made out of protein a suspected biocompatibility is already proven. The harmless amino acid hydrolysis products make the silk a good candidate for creating a bioresorbable textile scaffold. The chondrocytes cells adhere quite well on the spider cocoon silk threads. Cocoons can be obtained each autumn in large numbers from the Araneus diadematus garden spider. The mechanical properties of the silk are more appropriate than polymeric gels, like hyaluronic acid, collagen and alginate, which have proved to be successful in 3D immobilisation and maintaining the differentiated phenotype of chondrocytes. The phenotypical products collagen II and aggrecan were also detected around the cells growing on the spider cocoon silk. A silk 3D textile could possibly be applied in combination with a polymer gel, probably alginate, in order to achieve some biomechanical stability. While biodegradation is occurring, the silk textile is overgrown with real cartilage and eventually the wound will be recovered without any definitive synthetic implants.