Forensic Microscope

Collagen derived from chum salmon (Oncorhynchus keta) was crosslinked with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) during collagen fibrillogenesis and applied to an in vitro cell culture to evaluate its potential use as a scaffold for vascular tissue engineering. Human umbilical vein endothelial cells (HUVEC) were cultured on the crosslinked salmon collagen fibrillar gel (EDC-SC gel), and their growth rates and production levels of cytokines, including platelet-derived growth factor-BB and von Willebrand factor, were measured. Comparison was also made with bovine collagen gel crosslinked with EDC (EDC-BC gel). The growth and cytokine production of the HUVEC cultured on the EDC-SC gel were higher than those on the EDC-BC gel. In addition, HUVEC were found to attach to the EDC-BC gel through 2β1 integrin for native collagen, whereas they attached to the EDC-SC gel through vβ3 integrin for denatured collagen as well as the 2β1 integrin, indicating that HUVEC recognized denatured domains in the EDC-SC gel. In conclusion, the EDC-SC gel can be used as a scaffold to support HUVEC growth, although the integrin-mediated attachment manner differs between the two gels.

There is much literature on natural regeneration which emphasizes the importance of good seed year, but few authors consider seed input in terms of the combination of seed quantity (i.e. number of seeds) plus seed quality (i.e. percentage of viable seeds). We have considered both aspects and also attempted to identify the proportions of good vs poor quality seeds contributing to natural regeneration via ‘seed rain’ vs ‘cone drop’. In addition to studying seed input, we looked at the effects of vegetation control, ground preparation and protection from small mammals on seedling emergence and survival. Over a 3-year period (February 2001 to March 2004), there was enough seed production and seedling survival to conclude that natural regeneration could be successful beneath a 50-year-old stand of Corsican pine in the south of England. Peaks of pine seed release occurred in March/April in 2002 and 2003, but it was extremely surprising to observe that some seed was trapped in virtually every month of the 3-year study, demonstrating an almost continual release of (at least) small quantities of seeds. In line with this finding, although most pine seedlings were found shortly after peak seed dispersal in May, June and July; new seedlings were found in every month throughout the study except February and October. In general, vegetation control and ground preparation had a positive effect on seedling survival; the probability of a seedling surviving for 300 days was between 50 and 60 per cent.