Persistence of birefringence and specific collagen cross-links in dentine of teeth of the ‘Nuraghi’ population living in Sardinia BC 1500–1200

Well preserved bones of the Nuraghi population, discovered in 1980, are deposited in the Department of Biomedical Sciences, Division of Human Anatomy of the University of Sassari, in Sardinia, Italy. The Giant Tomb belongs to the megalithic monuments constructed in the period BC 1500–1200. The origin, history and the fate of Nuraghi population is not well known. Many cone-shaped fortresses are found in Sicily and megalithic monuments for burial purposes were built in their proximity. Due to the good macroscopic preservation of the mineralized parts of the Nuraghi skeletons we decided to compare the histological and biochemical structure of the recovered Nuraghi teeth with contemporary ones. Crown dentine of four Nuraghi molar and four premolar teeth were analysed and compared with contemporary molars and premolars removed for orthodontic reasons from 17–40-year-old patients in the Dental School, University of North Carolina at Chapel Hill USA. Evaluation of the collagen cross-links of dentine collagen was performed using a HPLC technique to analyze for hydrolysates. Nonreducible, stable cross-links pyridinoline and its lysyl analogue were quantified by fluorescence (excitation 330 nm, emission 390 nm). The concentration of reducible, labile cross-links referred to as DHLNL and HLNL (dehydro-dihydroxylisinorleucine) were identified and calculated by chromatography after the application of NaB³H₄ with integration of respective peaks and converting the numbers into a residue per mole of collagen basis. The ultrastructure of collagen was estimated by its persistent birefringence in polarized light after staining with Picrosirus Red. It was found that dentine collagen of Nuraghi teeth resisted environmental factors sufficiently well to preserve the molecular ultrastructure of collagen fibres, proved by their birefringence and by the preservation of some of the stable and reducible collagen cross-links, characteristic for skeletal tissues. © 1998 John Wiley & Sons, Ltd.     

The Conservation of Biodiversity in Iran: Threats,Challenges and Hopes

Because of its diverse geological formations, climates, and soils, Iran is home to outstanding biodiversity. National conservation started in Iran over fifty years ago and today nearly 10 percent of the country is protected. However, biodiversity in Iran is threatened, with about 100 species of vertebrate fauna vulnerable or endangered. Increased population and human activity, climate change, drought, desertification, agriculture, poaching, and economic sanctions have helped create this crisis. Many of these causes can be mitigated through better planning, sustainable policies, and increased civil society and local engagement. Promoting awareness about the impacts of human practices will also be important for the long-term sustainability of Iran’s ecosystems. Iranian conservation NGOs have already taken an active role in preserving biodiversity.