A new actinomycete strain SK4-6 producing secondary metabolite effective against methicillin-resistant Staphylococcus aureus

A new actinomycete strain designated SK4-6, was isolated. This organism exhibited strong activity against bacteria including methicillin-resistant Staphylococcus aureus and Micrococcus luteus, in addition to the causative agents of Candidiasis and Aspergillosis diseases, Candida albicans and Aspergillus species respectively. Morphological and chemical studies indicated that this organism belongs to the genus Streptomyces. Analysis of the 16S rRNA sequence of strain SK4-6 showed a high similarity, 99%, with S. qinlingensis. Optimization of cultural conditions was carried out using Plackett–Burman statistical design where seven variables were examined. Starch, pH and inoculum size showed a positive effect on the production of the active substances, however, sucrose, (NH₄)₂SO₄ and yeast extract repress the production.     

35S]autoradiographic study of sulfated GAG accumulation and turnover in embryonic mouse tooth germs

The accumulation of sulfated GAG in embryonic mouse molars before, during, and after terminal differentiation of odontoblasts was localized by [35S]autoradiography combined with the use of chondroitin ABC lyase. Much more sulfated GAG were accumulated in the dental papilla than in the dental epithelium. High incorporation of [35S]sulfate occurred at the epithelio-mesenchymal junction, which is the site of dental basement membrane and predentin. Before terminal differentiation of odontoblasts, the distribution of sulfated GAG was uniform at the basement membrane. After the onset of terminal differentiation of odontoblasts, much more sulfated GAG accumulated at the tip of principal cusps than at the apical (inferior) parts of cusps, and sulfated GAG were then found to be degraded more rapidly at the epithelio-mesenchymal junction than at other parts of the tooth germ. Thus regional variation in the rate of degradation of GAG exists in the tooth germs. Trypsin-isolated dental epithelia cultured in vitro synthesized a new basement membrane that could be labeled with [3H]glucosamine but not with 35SO4(-2). The epithelial-derived basal lamina contains little or no sulfatated GAG.