Enhanced model protein adsorption of nanoparticulate hydroxyapatite thin films on silk sericin and fibroin surfaces.

Hydroxyapatite coated metallic implants favorably combine the required biocompatibility with the mechanical properties. As an alternative to the industrial coating method of plasma spraying with inherently potential deleterious effects, sol-gel methods have attracted much attention. In this study, the effects of intermediate silk fibroin and silk sericin layers on the protein adsorption capacity of hydroxyapatite films formed by a particulate sol-gel method were determined experimentally. The preparation of the layered silk protein/hydroxyapatite structures on glass substrates, and the effects of the underlying silk proteins on the topography of the hydroxyapatite coatings were described. The topography of the hydroxyapatite layer fabricated on the silk sericin was such that the hydroxyapatite particles were oriented forming an oriented crystalline surface. The model protein (bovine serum albumin) adsorption increased to 2.62 µg/cm2 on the latter surface as compared to 1.37 µg/cm2 of hydroxyapatite on glass without an intermediate silk sericin layer. The BSA adsorption on glass (blank), glass/c-HAp, glass/m-HAp, glass/sericin/c-HAp, and glass/sericin/m-HAp substrates, reported as decrease in BSA concentration versus contact time.

Germination Biology of Two Invasive Physalis Species and Implications for Their Management in Arid and Semi-arid Regions.

Two Solanaceae invasive plant species (Physalis angulata L. and P. philadelphica Lam. var. immaculata Waterfall) infest several arable crops and natural habitats in Southeastern Anatolia region, Turkey. However, almost no information is available regarding germination biology of both species. We performed several experiments to infer the effects of environmental factors on seed germination and seedling emergence of different populations of both species collected from various locations with different elevations and habitat characteristics. Seed dormancy level of all populations was decreased with increasing age of the seeds. Seed dormancy of freshly harvested and aged seeds of all populations was effectively released by running tap water. Germination was slightly affected by photoperiods, which suggests that seeds are slightly photoblastic. All seeds germinated under wide range of temperature (15-40 °C), pH (4-10), osmotic potential (0 to -1.2 MPa) and salinity (0-400 mM sodium chloride) levels. The germination ability of both plant species under wide range of environmental conditions suggests further invasion potential towards non-infested areas in the country. Increasing seed burial depth significantly reduced the seedling emergence, and seeds buried below 4 cm of soil surface were unable to emerge. In arable lands, soil inversion to maximum depth of emergence (i.e., 6 cm) followed by conservational tillage could be utilized as a viable management option.

Invasion Potential of Two Tropical Physalis Species in Arid and Semi-Arid Climates: Effect of Water-Salinity Stress and Soil Types on Growth and Fecundity.

Invasive plants are recognized for their impressive abilities to withstand adverse environmental conditions however, all invaders do not express the similar abilities. Therefore, survival, growth, nutrient uptake and fecundity of two co-occurring, invasive Physalis species were tested under water and salinity stresses, and different soil textures in the current study. Five different water stress levels (100, 75, 50, 25, and 12.5% pot water contents), four different soil salinity levels (0, 3, 6, and 12 dSm-1) and four different soil textures (67% clay, 50% clay, silt clay loam and sandy loam) were included in three different pot experiments. Both weeds survived under all levels of water stress except 12.5% water contents and on all soil types however, behaved differently under increasing salinity. The weeds responded similarly to salinity up till 3 dSm-1 whereas, P. philadelphica survived for longer time than P. angulata under remaining salinity regimes. Water and salinity stress hampered the growth and fecundity of both weeds while, soil textures had slight effect. Both weeds preferred clay textured soils for better growth and nutrient uptake however, interactive effect of weeds and soil textures was non-significant. P. angulata accumulated higher K and Na while P. philadelphica accrued more Ca and Mg as well as maintained better K/Na ratio. P. angulata accumulated more Na and P under salinity stress while, P. philadelphica accrued higher K and Mg, and maintained higher K/Na ratio. Collectively, highest nutrient accumulation was observed under stress free conditions and on clay textured soils. P. philadelphica exhibited higher reproductive output under all experimental conditions than P. angulata. It is predicted that P. philadelphica will be more problematic under optimal water supply and high salinity while P. angulata can better adapt water limited environments. The results indicate that both weeds have considerable potential to further expand their ranges in semi-arid regions of Turkey.