Structural characterization of two isolectins from the marine red alga Solieria filiformis (Kützing) P.W. Gabrielson and their anticancer effect on MCF-7 breast cancer cells.

As described in the literature, Solieria filiformis lectin (SfL) from the marine red alga S. filiformis was found to have antinociceptive and anti-inflammatory effects. In this study, we characterized two SfL variants, SfL-1 and SfL-2, with molecular mass of 27,552Da and 27,985Da, respectively. The primary structures of SfL-1 and SfL-2 consist of four tandem-repeat protein domains with 67 amino acids each. SfL-1 and -2 showed high similarity to OAAH-family lectins. 3D structure prediction revealed that SfL-1 and -2 are composed of two ß-barrel-like domains formed by five antiparallel ß-strands, which are connected by a short peptide linker. Furthermore, the mixture of isoforms (SfLs) showed anticancer effect against MCF-7 cells. Specifically, SfLs inhibited 50% of viability in MCF-7 cells after treatment at 125µg.mL-1, while the inhibition of Human Dermal Fibroblasts (HDF) was 34% with the same treatment. Finally, 24h after treatment, 25% of MCF-7 cells were in early apoptosis and 35% in late apoptosis. Evaluation of pro- and anti-apoptotic gene expression of MCF-7 cells revealed that SfLs induced caspase-dependent apoptosis within 24h.

Toxicity and binding profile of lectins from the Genus canavalia on brine shrimp.

Lectins are sugar-binding proteins widely distributed in nature with many biological functions. Although many lectins have a remarkable biotechnological potential, some of them can be cytotoxic. Thus, the aim of this study was to assess the toxicity of five lectins, purified from seeds of different species of Canavalia genus. In order to determine the toxicity, assays with Artemia nauplii were performed. In addition, a fluorescence assay was carried out to evaluate the binding of lectins to Artemia nauplii. In order to verify the relationship between the structure of lectins and their cytotoxic effect, structural analysis was carried out to evaluate the volume of the carbohydrate recognition domain (CRD) of each lectin. The results showed that all lectins exhibited different toxicities and bound to a similar area in the digestive tract of Artemia nauplii. Concerning the structural analysis, differences in spatial arrangement and volume of CRD may explain the variation of the toxicity exhibited by each lectin. To this date, this is the first study that establishes a link between toxicity and structure of CRD from Diocleinae lectins.

Characterization of isoforms of the lectin isolated from the red algae Bryothamnion seaforthii and its pro-healing effect.

Lectins are a structurally heterogeneous group of proteins that have specific binding sites for carbohydrates and glycoconjugates. Because of their biotechnological potential, lectins are widely used in biomedical research. The present study aimed to evaluate the healing potential of the lectin isolated from the marine red alga Bryothamnion seaforthii (BSL). The lectin was purified using ion exchange chromatography with DEAE cellulose and characterized using tandem mass spectrometry. For healing tests, skin wounds were induced in the dorsal thoracic region of mice. These animals were randomly divided into three groups and subjected to topical treatment for 12 days with BSL, bovine serum albumin and 150 mM NaCl. To evaluate the potential of each treatment, the animals were anesthetized and sacrificed on days 2, 7 and 12, respectively. The parameters evaluated included the wound area, the proportion of wound closure and the histological diagnosis. The wound closure was more effective with BSL (Postoperative Day 7 and 12) than controls. The luminal epithelium was completely restructured; the presence of collagen in the dermis and the strongly active presence of young skin annexes demonstrate the potential of treatment with BSL compared with controls. Our findings suggest that BSL has pro-healing properties and can be a potential medical process in the treatment of acute wounds.

Lab-scale periphyton-based system for fish culture / Sistema laboratorial baseado em perifíton para piscicultura

The present research aimed to assess a lab-scale model to study periphyton-based systems for fish culture. Twenty-five liters plastic aquaria were stocked with three Nile tilapia, Oreochromis niloticus, juveniles (0.77±0.09g; 12 fish m-2) for 6 weeks in a 2x2 factorial design. Small plastic bottles were placed in some aquaria for periphyton development. Two feeding regimes were employed: "full-fed" (standard feeding rates were fully adopted) and "half-fed" (50 percent of standard feeding rates). Growth performance and limnological variables were observed in each aquarium. There werefive replicates per treatment. Fish have fed actively on periphyton, especially in the half-fed aquaria. The placement of periphyton bottles had no significant effects on the water quality variables, except by the gross primary productivity which became lower. Half-fed aquaria presented lower concentrations of ammonia (0.28-0.29mg L-1), nitrite (0.33-0.37mg L-1) and phosphorus (0.42-0.43mg L-1) than full-fed aquaria (0.57-0.60mg L-1; 0.75-0.77mg L-1; 0.67-0.70mg L-1, respectively). The final body weight of fish in half-fed aquaria with periphyton bottles (6.22±0.64g) was significantly higher than in aquaria without bottles (4.65±0.36g). Although the growth rate of fish was lower in the half-fed aquaria (4.27-4.72 vs. 5.29-5.61 percent BW day-1), survival was significantly higher when compared to the full-fed aquaria (93.3-100.0 vs. 80.0-83.4 percent). Only in the aquaria with periphyton the feed conversation ratio was improved by the feeding restriction regime.

O presente trabalho teve como objetivo avaliar um modelo laboratorial para estudo de sistemas de cultivo de peixes baseados em perifíton. Aquários de 25L foram estocados com três juvenis de tilápia do Nilo, Oreochromis niloticus (0,77±0,09g; 12 peixes m-2) por seis semanas, em arranjo fatorial 2x2. Pequenas garrafas plásticas foram colocadas em determinados aquários para o desenvolvimento de perifíton. Dois regimes alimentares foram empregados: "cheio", no qual taxas alimentares padrões foram integralmente adotadas e "metade", em que 50 por cento das taxas alimentares regulares foram empregadas. Variáveis limnológicas e de desempenho zootécnico foram observadas em cada aquário. Havia cinco repetições por tratamento. Os peixes ingeriram ativamente perifíton, especialmente os que receberam metade do arraçoamento padrão. A colocação de garrafas para o crescimento de perifíton não teve efeito significativo nas variáveis de qualidade de água, excetuando-se na produtividade primária bruta que foi menor. Os aquários arraçoados pela metade apresentaram menores concentrações de amônia (0,28-0,29mg L-1), nitrito (0,33-0,37mg L-1) e fósforo (0,42-0,43mg L-1) que os aquários arraçoados integralmente (0,57-0,60mg L-1; 0,75-0,77mg L-1; 0,67-0,70mg L-1, respectivamente). O peso corporal final dos peixes nos aquários arraçoados pela metade, mas com garrafas para perifíton (6,22±0,64g), foi significativamente maior que nos respectivos aquários sem garrafas (4,65±0,36g). Embora a taxa de crescimento dos peixes alimentados com metade das taxas regulares tenha sido menor (4,27-4,72 vs. 5,29-5,61 por cento PC dia-1), a sobrevivência foi significativamente maior para estes, quando comparados com os peixes alimentados com taxas regulares (93,3-100,0 vs. 80,0-83,4 por cento). Apenas nos aquários com perifíton a conversão alimentar foi melhorada pela restrição alimentar imposta.