Use of Spirulina platensis micro and nanoparticles for the removal synthetic dyes from aqueous solutions by biosorption

In this research, micro and nanoparticles of Spirulina platensis dead biomass were obtained, characterized and employed to removal FD&C red no. 40 and acid blue 9 synthetic dyes from aqueous solutions. The effects of particle size (micro and nano) and biosorbent dosage (from 50 to 750 mg) were studied. Pseudo-first order, pseudo-second order and Elovich models were used to evaluate the biosorption kinetics. The biosorption nature was verified using energy dispersive X-ray spectroscopy (EDS). The best results for both dyes were found using 250 mg of nanoparticles, in these conditions, the biosorption capacities were 295 mg g^?1 and 1450 mg g^?1, and the percentages of dye removal were 15.0 and 72.5% for the FD&C red no. 40 and acid blue 9, respectively. Pseudo-first order model was the more adequate to represent the biosorption of both dyes onto microparticles, and Elovich model was more appropriate to the biosorption onto nanoparticles. The EDS results suggested that the dyes biosorption onto microparticles occurred mainly by physical interactions, and for the nanoparticles, chemisorption was dominant.     

Reproductive allocation in rhizomatous,seminiferous, and pseudoviviparous Leiothrix (Eriocaulaceae) species

Pseudoviviparous species are considered to rely almost entirely on vegetative propagation, because flowers are replaced by sprouts, and seedling recruitment is rare. We compared reproductive allocation (inflorescence and seed production) in three propagation modes presented by sympatric species of Leiothrix (Eriocaulaceae): rhizomatous and seminiferous (RS—L. crassifolia); rhizomatous, seminiferous, and pseudoviviparous (RSP—L. spiralis); and seminiferous and pseudoviviparous, in which seed production is considered rare due to reduced inflorescence size and small number of pistillate flowers (SP—L. arrecta and L. propinqua). We hypothesize that such propagation modes constitute a continuum of reproductive investment, that is: RS > RSP > SP. We harvested 154 Leiothrix spp. individuals at the Serra do Cipó, SE Brazil, from which we recorded the number of capitula and seeds, mean seed weight, and dry biomass allocated to plant structures. We then compared distinct propagation modes in relation to reproductive allocation, inflorescence-based and seed-based reproductive effort, and biomass partitioning. Contrary to expectations, the reproductive investment hierarchy found was SP ≥ RS > RSP. Our results do not fully concur with the current view that pseudoviviparous plants allocate few resources to reproduction. We suggest that the larger reproductive investment observed in SP helps to wait for better recruitment conditions in crowded and highly competitive mature populations (temporal escape), and to cope with destructive disturbances such as fire, since SP species lacks rhizomes.     

Urinary excretion of glycosaminoglycans and albumin in experimental diabetes mellitus

Diabetes mellitus was induced in one group of rats by a single injection of streptozotocin. The glycemia, the body weight, and the blood systolic pressure were measured every week, and the 24 h urine volume and urinary excretions of creatinine, albumin and glycosaminoglycans were measured every 2 weeks. At the end of the experiment (12 weeks) the weight and the glycosaminoglycan composition of the kidneys were determined. All the diabetic animals were hyperglycemic, hypertense, and did not gain weight during all the experimental period. Albuminuria appeared from the second week on. Rat urine was shown to contain heparan sulfate, chondroitin sulfate, and dermatan sulfate, and the glycosaminoglycan excretion decreased in all diabetic animals. The onset of the change in glyco-samino-glycan excretion rate was a very early event, appearing in the second week after diabetes induction. The main glycosaminoglycan found in normal rat kidney was heparan sulfate and, in contrast to the urine, the total kidney glycosaminoglycans increased in diabetic kidney, due to chondroitin sulfate and dermatan sulfate accumulation. The heparan sulfate concentration (per tissue dry weight) did not change. Our results suggest that quantification of urinary glycosaminoglycans may be a useful tool for the early diagnosis of diabetic nephropathy.