Karyological and electrophoretic differences between <i>Pomacea flagellata</i> and <i>P. patula catemacensis</i> (Caenogastropoda: Ampullariidae)

The widespread Mexican apple snail Pomacea flagellata (Say 1827) and the strictly endemic "tegogolo" P. patula catemacensis (Baker 1922) (restricted to Lake Catemaco), are the only known American Ampullariidae that have haploid complements n=13. Pomacea patula catemacensis has suffered a critical reduction in abundance due to immoderate fishing for human consumption. Chromosome slides were obtained from colchicine-injected Pomacea snails collected from nine locations along the coastal zone of the Gulf of Mexico, including Lake Catemaco, for use in principal component analysis (PCA). Total proteins in foot homogenates were analyzed through isoelectric focusing (IEF) and native-PAGE electrophoresis on polyacrylamide gels. The chromosome number 2n=26 was confirmed for snails from all locations, with a uniform 9 m + 4 sm formula. However, P. patula catemacensis showed significantly larger chromosomes (absolute size) than any population of P. flagellata. Pomacea patula catemacensis also differed from all populations of P. flagellata in a PCA with standardized data, i.e., independently of the absolute size difference between species. Proteins with an acid isoelectric point were dominant in the foot of both species. The electrophoresis analysis showed that P. flagellata has 17 protein bands, with an upper bound at IEF=7.6, while P. patula catemacensis has only 15 bands, with an upper bound at IEF=7 and a more evenly spaced band pattern. Molecular weights ranged from 40 to approximately 130 kDa in both species. Proteins with high values (>94 kDa) were the most abundant. Pomacea patula catemacensis showed a band of 93 kDa, which was absent from all specimens of P. flagellata. Samples of P. flagellata did not cluster according to any geographical pattern in the statistical analyses, nor did they show any taxonomically useful differences in their electrophoretic patterns that merit sub-specific discrimination.     

Brief Note : Improved <i>in vitro</i> embryo development of stenospermic grape by putrescine

The goal of this study was to determine the effect of putrescine, added to the culture medium, on the in vitro development of stenospermic grape (Vitis vinifera L) embryos. The cross breedings of Perlón x G.C88552 and Perlón x Argentina were used. 0 (control), 2 and 4 mM of putrescine were added to the immature seed’s culture medium. In Perlón x Argentina, 2mM of putrescine statistically increased the percentage of total embryos, direct germination, polyembryos and normal plants. In Perlón x G.C88552, only 2 mM of putrescine increased all the variables considered, eventually tripling the percentage of normal plants obtained. The results suggest that the endogenous concentration of putrescine may be a growth limiting factor. Adding putrescine to the culture medium of immature grape seeds is a legitimate resource to significantly increase the results of this technique.     

Edematogenic and myotoxic activities of the duvernoy’s gland secretion of <i>Philodryas olfersii</i> from the north-east region of Argentina

Philodryas olfersii is found in South America, from Amazonas to Patagonia. It is important to characterize the venom of P. olfersii, who inhabits the North-East region of Argentina, since snake venoms are known to exhibit considerable variability in composition and biological activities. In this work, mice weighing 18-20 g (n = 4 for each experimental group) were used. For the edematogenic activity mice were injected s.c. in the right foot pad with 50 µl of solutions containing different amounts of venom, whereas the left foot pad was injected with 50 µl of PBS. Two hours after injection mice were killed by cervical dislocation and both feet were cut off and weighed individually. For the myotoxic activity mice were injected i.m. with 100 µl of solutions containing 40 µg of venom. Blood samples were extracted after 1, 3, 6, 8, 10, 12, 14, 16 and 24 h of venom injection to determinate serum CPK activity and mice were sacrificed at the same time intervals to obtain the inoculated gastrocnemius muscle. They were fixed with Bouin solution and stained with Hematoxylin-Eosin. Results showed that P. olfersii venom exhibits a high edematogenic activity (MED = 0.31 µg) and a moderate myotoxic activity. Myonecrosis reached its highest level after 12 h of venom injection as shown by plasmatic CPK levels (5,401 ± 330 IU/l) and microscopic assay. It demonstrates the potential toxicity of the venom of P. olfersii, who inhabits the North-East region of Argentina. It also reinforces the original warning concerning the potential danger of bites by colubrids.     

Physicochemical and antioxidant properties of bovine caseinate hydrolysates obtained through microbial protease treatment

It is currently possible to obtain bioactive nutritional components through enzyme hydrolysis under well‐controlled and moderate conditions of pH and temperature. In this work, we aimed for the production and characterisation of bovine sodium caseinate (NaCAS) hydrolysates by means of an extracellular protease from Bacillus sp. P45. Antioxidant properties were evaluated through 2,2‐diphenyl‐1‐picrylhydrazyl and thiobarbituric acid reactive substances assays. A glucono‐δ‐lactone acid‐induced aggregation and gelation processes of the hydrolysates and their corresponding mixtures with NaCAS were also analysed. Hereby, we demonstrate that the presence of hydrolysates affects the kinetics of NaCAS aggregation processes but does not significantly alters the final state of the acid aggregates obtained.     

Effect of heat treatment on the antibacterial activity of bovine lactoferrin against three foodborne pathogens

The effect of different heat treatments on the antimicrobial activity of bovine lactoferrin against Escherichia coli O157:H7, Salmonella enteritidis and Listeria monocytogenes has been studied. We have observed that the heat treatments lower than 85°C for 10 min did not affect the antibacterial activity of the protein. Hydrolysates of bovine lactoferrin were found to be more active than the native protein against the three pathogens. Moreover, the antibacterial effect of bovine lactoferrin was also assayed in milk and whey, and although we found a reduction in the number of viable cells, this reduction was lower than in culture media.     

MECHANICAL PROPERTIES AND VISCOELASTIC CHARACTERISTICS OF TWO VARIETIES OF YAM TUBERS (DIOSCOREA ALATA)

The main mechanical properties and viscoelastic characteristics of two different cultivars of yam have been measured in this work. Using an Instron machine, some different tests has been applied: puncture, uniaxial compression and bending in order to calculate the parameters: maximum stress of penetration, stress and strain at fracture, deformability modulus and the constants " a " and " b " from the Peleg model. It is concluded that the Pico de Botella cultivar has a fracture stress higher (0.57 MPa) than the Diamante 22 cultivar (0.31 MPa). Also, the degree of deformation at fracture is higher (32 versus 21%). In relation with the constants from the Peleg viscoelasticity model, there are no differences between cultivars, both having the same value of the asintotic stress ( a =  0.43) and very similar for the relaxation stress rates (Pico de Botella, b =  0.03 and Diamante 22, b =  0.02).

PRACTICAL APPLICATIONS

Information on mechanical properties of yam that has not been reported in the literature.     

DNA mismatch repair gene methylation in gastric cancer in individuals from northern Brazil

Gastric cancer is one of the most common malignancies. DNA methylation is implicated in DNA mismatch repair genes deficiency. In the present study, we evaluated the methylation status of MLH1, MSH2, MSH6 and PMS2 in 20 diffuse- and 26 intestinal-type gastric cancer samples and 20 normal gastric mucosal of gastric cancer patients from Northern Brazil. We found that none of the nonneoplastic samples showed methylation of any gene promoter and 50% of gastric cancer samples showed at least one methylated gene promoter. Methylation frequencies of MLH1, MSH2, MSH6 and PMS2 promoter were 21.74%, 17.39%, 0% and 28.26% respectively in gastric cancer samples. MLH1 and PMS2 methylation were associated with neoplastic samples compared to nonneoplastic ones. PMS2 methylation was associated with diffuse- and intestinal-type cancer compared with normal controls. Intestinal-type cancer showed significant association with MLH1 methylation. Diffuse-type cancer was significantly associated with MSH2 methylation. Our findings show differential gene methylation in tumoral tissue, which allows us to conclude that methylation is associated with gastric carcinogenesis. Methylation of mismatch repair genes was associated with gastric carcinogenesis and may be a helpful tool for diagnosis, prognosis and therapies. However, MSH6 does not seem to be regulated by methylation in our samples.     

New evidence for a role of Bisphenol A in cell integrity. Implications in the human population

Bisphenol A (BPA) is a xenoestrogen known for its implications for the endocrine systems and several other organs, including the kidneys. Recent renal studies have shown that BPA can induce alterations of the cytoskeleton and cell adhesion mechanisms such as a podocytopathy with proteinuria and hypertension, alterations involved in the progression of renal diseases. These data and the fact that BPA is known to be present in the urine of almost the entire population strongly suggest the critical need to reevaluate BPA exposures considered safe.