Neural Differentiation of Human-Induced Pluripotent Stem Cells (hiPSc) on Surface-Modified Nanofibrous Scaffolds Coated with Platelet-Rich Plasma

The field of tissue engineering exploits living cells in a variety of ways to restore, maintain, or enhance tissues and organs. Between stem cells, human induced pluripotent stem cells (hiPSCs), are very important due to their wide abilities. Growth factors can support proliferation, differentiation, and migration of hiPSCs. Platelet-rich plasma (PRP) could be used as the source of growth factors for hiPSCs. In the present study, proliferation and neural differentiation of hiPSCs on surface-modified nanofibrous Poly-l-lactic acid (PLLA) coated with platelet-rich plasma was investigated. The results of in vitro analysis showed that on the surface, which was modified nanofibrous scaffolds coated with platelet-rich plasma, significantly enhanced hiPSCs proliferation and neural differentiation were observed. Whereas the MTT ([3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide]) results showed biocompatibility of surface-modified nanofibrous scaffolds coated with platelet-rich plasma and the usage of these modified nanoscaffolds in neural tissue engineering in vivo is promising for the future.

     

Variation in seed dormancy and germination among populations of Silybum marianum (Asteraceae)

Milk thistle (Silybum marianum) is a medicinal plant; however, lack of consistency in past dormancy studies has hindered propagation of this species from seeds. We tested the germination responses of freshly harvested and after-ripened (stored for 2 and 7 months; 25°C at 50% relative humidity) seeds from three populations (P1, P2 and P3) in Iran at varying constant or alternating temperatures, with or without GA₃ and in light and continuous darkness. No germination occurred in freshly harvested seeds incubated at any condition without GA₃ application, indicating that all the seeds were dormant. Seeds from P1 and P2, which developed under relatively dry, warm conditions, germinated over a wider range of temperatures after 2 months of dry storage, indicating type 6 of non-deep physiological dormancy (PD). Seeds from P3, which developed under relatively wet, cool conditions, incubated at constant temperatures (especially on GA₃), exhibited an increase in maximum temperature for germination, indicating type 1 of non-deep PD. Light improved germination of after-ripened seeds, and GA₃ application substituted for the light requirement for germination. This is the first report that environmental conditions during seed development may be correlated with differences in the type of non-deep PD. We conclude that milk thistle seeds are positively photoblastic and photodormant and the germination responses of after-ripened seeds from different populations are different under darkness. Therefore, the impacts of genetic differences and maternal effects on the induction of dormancy during seed development should be considered in attempts to domesticate this medicinal plant.     

Adhesion of Pseudomonas putida onto Palygorskite and Sepiolite Clay Minerals

Adhesion of bacteria to clay minerals is of great importance in both natural soil environments and technological applications. In the present study, equilibrium experiments along with Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and energy-dispersive X-ray analysis (EDX) were used to investigate the adhesion of Pseudomonas putida to the palygorskite and sepiolite clay minerals. The results showed that bacterial adhesion was rapid and reached equilibrium within 30 min. Equilibrium data showed that sepiolite has higher capacity and affinity than palygorskite for P. putida retention. Mixed FT-IR peak features of the clay minerals and P. putida were observed in the clay–bacteria complex spectra, indicating significant adhesion of P. putida to the minerals. However, some differences in the position of the individual bands were observed between infrared spectra obtained for pure bacteria or clay minerals and their corresponding clay–bacteria complexes, which are believed to be related to clay–bacteria interactions via different mechanisms. SEM/EDX analysis demonstrated fine fibrous clay particles adhered to the surface of individual P. putida cells. The results revealed rapid and close interactions of palygorskite and sepiolite with P. putida cells, which is important for better understanding the fate of bacteria in soil systems dominated by fibrous clay minerals and their practical applications in bioengineering and biotechnology.     

Effects of different extracellular matrices and co-cultures on human limbal stem cell expansion in vitro

To elucidate the effect of extracellular matrices (ECMs) and related and nonrelated-limbal feeder cells as substitutes for the in vivo niche on the phenotype and genotype of the limbal stem cell (SC) expansion in vitro, human limbal SCs were used. The limbus explants were expanded on human amniotic membrane (AM), commercial ECMs including matrigel (MAT), collagen (COL), and control (no ECM) in presence and absence of feeder cells including human limbal fibroblasts (LFs), a limbus-specific cell and mouse embryonic fibroblasts (MEFs). Proliferation, cell death, immunocytochemistry, expression of specific genes, ultrastructural characteristics, and size and granularity of expanded human limbal SCs in different groups were evaluated. The growth, cell proliferation, and survival of limbal SCs were enhanced by AM and MAT matrices. Ultrastructure and expression of stemness markers revealed that there was no significance difference between AM and MAT. However, flow cytometric analysis showed that the size and granularity of cultured cells increased in the presence of MAT and COL as well as in no ECM group. Moreover, co-culturing of limbal explants with LFs and MEFs on AM and MAT groups, enhanced the expansion and survival of cultured cells in comparison with others. In conclusion, the cultivation of human limbal explants on AM co-culturing with human LFs promises to be a good model for preparing undifferentiated epithelial sheets suitable for transplantation.     

Dinoflagellate Endosymbiont of the Soft Coral Stichodactyla haddoni Saville-Kent Collected from the Coast of Hormuz Island,Strait of Hormuz

Russian Journal of Marine Biology - An endosymbiotic dinoflagellate isolated from the soft coral Stichodactyla haddoni from the coast of Hormuz Island, Strait of Hormuz, Persian Gulf, has been...     

Effect of water stress on growth, osmotic adjustment, cell wall elasticity and water-use efficiency in Spartina alterniflora

In the northern spring–summer season of 2004–2005, vegetative propagated plants of Spartina alterniflora were grown under control and water stress conditions on the Mediterranean sea shore of the south-east of Tunis. Control plants were irrigated every week and water stress plants were irrigated until the soil achieved 50% (mild stress) and 25% (severe stress) field capacity (FC). Dry and fresh weight at the whole plant level (g plant⁻¹), shoot to root ratio on dry and fresh weight, photosynthesis (A), transpiration rate (E), instantaneous water-use efficiency (WUE_i), leaf water potential (Ψw), leaf water content (WC), osmotic potential at full turgor (Ψs¹⁰⁰), osmotic potential at turgor loss point (Ψs⁰), osmotic adjustment (OA), proline, sugars, inorganic compounds and cell wall elasticity (CWE) were evaluated during a period of 6 days period between 82 and 90 days after the beginning of treatment (DAT). Plants grown under severe and mild-water stress showed lower Ψw than in control plants with values that averaged −3.1, −1.6 and −0.9 MPa, respectively. S. alterniflora plants submitted to mild-water stress exhibited OA and a decrease in CWE. However, under severe water stress the OA was not observed and CWE also decreased, but it was higher than in the mild-water stress. OA was mainly explained by the accumulation of nitrates, sugars and at a lesser degree, proline. S. alterniflora had a strong decline of the dry and fresh weight of the whole plant associated to a marked decrease of photosynthesis (A) and transpiration (E) in response to water stress, although WUE_i was increased. These results suggest that OA and WUE_i can be important components of the water stress adaptation mechanism in this species, but they are not sufficient enough to contribute to resistance to water stress.     

Resveratrol Attenuates Copper and Zinc Homeostasis and Ameliorates Oxidative Stress in Type 2 Diabetic Rats

Diabetes is a common metabolic disorder characterized by elevated blood glucose level. Trace element homeostasis causes disturbances in diabetes due to hyperglycemia. Superoxide dismutase (SOD), an antioxidant enzyme, contains zinc and copper ions as its cofactors. Defects in SOD level and activity have been observed in diabetes. Resveratrol (RSV) has displayed hypoglycemic effects and is proven to improve oxidative stress. The aim of the present study was to examine the possible effects of RSV on blood glucose level, serum copper and zinc levels, SOD, and a number of other oxidative markers in type 2 diabetic rats. Diabetes was induced in male Wistar rats with administration of streptozotocin and nicotine amide. The studied groups containing six animals per group were as follows: group 1 normal control group; group 2 diabetic control group; groups 3, 4, and 5 diabetic rats that received 1, 5, and 10 mg/kg body weight of RSV, respectively for 30 days. Serum glucose, copper, zinc, SOD activity, total oxidant status (TOS) as well as thiol groups were all measured. Blood glucose in RSV treated groups significantly decreased. Similarly, copper significantly decreased in diabetic groups treated with RSV. Treatment with 10 mg/kg RSV resulted in significantly increased serum zinc. Furthermore, Cu/Zn ratio was observed to decrease in treated groups compared with untreated diabetic control group. RSV treated groups revealed an increased level of SOD activity as well as improved oxidative status. In summary, the results showed that RSV has potential hypoglycemic effect, attenuates trace element homeostasis, and consequently increases SOD activity level.