ABSTRACT
The availability of nesting resources influences the persistence and survival of bee communities. Although a positive effect of artificial nesting structures has frequently been shown for aboveground cavity-nesting wild bees, studies on below ground-nesting bees are rare. Artificial nesting hills designed to provide nesting habitats for ground-nesting bees were therefore established within the BienABest project in 20 regions across Germany. Wild bee communities were monitored for two consecutive years, accompanied by recordings of landscape and abiotic nest site variables. Bee activity and species richness increased from the first to the second year after establishment; this was particularly pronounced in landscapes with a low cover of semi-natural habitat. The nesting hills were successively colonized, indicating that they should exist for many years, thereby promoting a species-rich bee community. We recommend the construction of nesting hills on sun-exposed sites with a high thermal gain of the substrate because the bees prefer south-facing sites with high soil temperatures. Although the soil composition of the nesting hills plays a minor role, we suggest using local soil to match the needs of the local bee community. We conclude that artificial nesting structures for ground-nesting bees act as a valuable nesting resource for various bee species, particularly in highly degraded landscapes. We offer a construction and maintenance guide for the successful establishment of nesting hills for bee conservation.
ABSTRACT
Our aim was to determine the spectrum and accumulation of mutations in surveillance biopsies from Barrett's mucosa of individual patients during follow-up. We performed loss of heterozygosity (LOH) analysis of six recently described tumor suppressor genes relevant for the carcinogenesis of Barrett's adenocarcinoma from laser-microdissected, paraffin-embedded biopsy samples of Barrett's mucosa without or with low-grade dysplastic change. 118 biopsy samples from 26 patients were taken during surveillance programs in time intervals ranging between 6 and 51 months. We found no significant increase in LOH events at least in a 51-month interval. In two patients, Barrett's adenocarcinoma was diagnosed 6 months after the first diagnosis of Barrett's mucosa. Six of 26 patients did not show LOH. The remaining patients exhibited a striking variation of LOH patterns and accumulations in biopsy samples during follow-up. From our microsatellite marker panel, we were not able to define a single surrogate marker that could serve as a potential biomarker, indicating an increased risk of progression to Barrett's adenocarcinoma. However, LOH combinations, especially APC/p16(INK4) or APC/p53, deserve attention as putative biomarkers in future studies. Our results raise important questions regarding the biological dynamics of mutations in Barrett's mucosa in addition to the influence of sampling, especially with regard to the number of biopsies taken from Barrett's mucosa.
