Cell-permeable peptides induce dose- and length-dependent cytotoxic effects

We have explored the threshold of tolerance of three unrelated cell types to treatments with potential cytoprotective peptides bound to Tat_48-57 and Antp_43-58 cell-permeable peptide carriers. Both Tat_48-57 and Antp_43-58 are well known for their good efficacy at crossing membranes of different cell types, their overall low toxicity, and their absence of leakage once internalised. Here, we show that concentrations of up to 100 μM of Tat_48-57 were essentially harmless in all cells tested, whereas Antp_43-58 was significantly more toxic. Moreover, all peptides bound to Tat_48-57 and Antp_43-58 triggered significant and length-dependent cytotoxicity when used at concentrations above 10 μM in all but one cell types (208F rat fibroblasts), irrespective of the sequence of the cargo. Absence of cytotoxicity in 208F fibroblasts correlated with poor intracellular peptide uptake, as monitored by confocal laser scanning fluorescence microscopy. Our data further suggest that the onset of cytotoxicity correlates with the activation of two intracellular stress signalling pathways, namely those involving JNK, and to a lesser extent p38 mitogen-activated protein kinases. These responses are of particular concern for cells that are especially sensitive to the activation of stress kinases. Collectively, these results indicate that in order to avoid unwanted and unspecific cytotoxicity, effector molecules bound to Tat_48-57 should be designed with the shortest possible sequence and the highest possible affinity for their binding partners or targets, so that concentrations below 10 μM can be successfully applied to cells without harm. Considering that cytotoxicity associated to Tat_48-57- and Antp_43-58 bound peptide conjugates was not restricted to a particular type of cells, our data provide a general framework for the design of cell-penetrating peptides that may apply to broader uses of intracellular peptide and drug delivery.     

Genetic structure of the red mangrove (<Emphasis Type="Italic">Rhizophora mangle</Emphasis> L.) on the Colombian Pacific detected by microsatellite molecular markers

Rhizophora mangle, one of the five species of the genus Rhizophora, is found widely distributed along the American and West African coasts. This species is one of the principal constituents of the mangrove ecosystem in Colombia and is also found within the most important economic activities for the communities that inhabit the littoral. In order to assess the degree of genetic diversity of R. mangle in five populations of the Colombian Pacific, nuclear microsatellite molecular markers were used. In 92 individuals sampled, it was found that 100% of the loci were polymorphic , and no private alleles were detected. The population structure of R. mangle in the Colombian Pacific, was highly significant (P < 0.001); however, the greatest differentiation was detected at the within-population level (94.62%). For the populations of La Plata, Virudó and Charambirá, the tendency toward panmixia could be the cause of the low differentiation among these three locations. Within populations, the genetic diversity revealed a deviation from Hardy–Weinberg equilibrium with high significance in Virudó and Tumaco, where it appears the intense anthropogenic activity has exercised strong pressure on the red mangrove, resulting in the possible fragmentation of the local landscape and therefore an increase in the rate of endogamy within these populations. Despite this situation, our study―one of the first developed in genetics of the red mangrove in Colombia―did not show evidence of recent bottleneck effects or deterioration in its genetic composition, which could be exploited to propose management and restoration programs for the zones where the forests of this species are degraded. Handling editor: K. Martens     

Potential mineralization of nitrogen from organic wastes to ryegrass and wheat crops

Two-pot experiments with ryegrass and wheat plants were conducted in a Cambic Arenosol to test the reliability of N fate predicted by incubation experiments previously performed, with the same soil, to assess potentially mineralizable nitrogen from six organic wastes (municipal solid waste compost, secondary pulp mill sludge, horn meal, poultry manure, solid phase from pig slurry and composted pig manure). Two treatments, corresponding to 80 and 160 kgN/ha were tested, with or without mineral N fertilization. Experimental data obtained in the pot trials was consistent with nitrogen net mineralization trend observed in the aerobic incubations with all the wastes tested. Values of potentially mineralizable nitrogen (N(0)) from the equations obtained by model fitting, to the incubation data, were well correlated to ryegrass and wheat N uptake. Poultry manure was the most efficient N supplier to crops.     

Occurrence of enterotoxigenic and nonenterotoxigenic Bacteroides fragilis in calves and evaluation of their antimicrobial susceptibility

Bacteroides fragilis is considered an important clinical pathogen and the most common anaerobe isolated from human and animal clinical specimens; enterotoxigenic strains produce diarrhea. The presence of enterotoxigenic (ETBF) and nonenterotoxigenic B. fragilis in stool samples from calves with or without acute diarrhea and the antimicrobial susceptibility of the strains were evaluated. The stool samples were plated onto a selective B. fragilis-bile-esculin agar, and incubated anaerobically (10% CO(2)/90% N(2)), at 37 degrees C, for 72 h. Species of the B. fragilis group were identified by using the API 32-A kit. Enterotoxigenic strains were detected by PCR and the cytotoxic assay. From 54 diarrhea and 54 nondiarrhea stools, 124 and 92 members of the B. fragilis group, respectively, were recovered. Only two ETBF strains were isolated from two different diarrhea samples and the bft gene was detected in both. Moreover, the bft gene was detected in DNA from four different diarrheal stools samples but no ETBF strain was recovered. All the bacteria were susceptible to chloramphenicol, imipenem, moxifloxacin, piperacillin/tazobactam, metronidazole and tigecycline. Most of the isolates from both calves with and without diarrhea were resistant to all metals. Our results are of concern, and suggest the need to increase the surveillance of antibiotic and metal resistance of this microbial group isolated from animal production such as calves.     

Chromanones with leishmanicidal activity from Calea uniflora

The dichloromethane extract of Calea uniflora afforded a mixture of two novel chromanones, uniflorol-A (1) and uniflorol-B (2), and one known chromanone, 2,2-dimethyl-6-(1-hydroxyethyl)-chroman-4-one (3). The structures of these compounds were determined by spectroscopic methods. Biological activity of the compounds against Leishmania major promastigotes was evaluated. Mixture of the novel chromanones 1 and 2 showed significant growth inhibition of the parasite in the micrograms per milliliter range.     

Biological hydroperoxides and singlet molecular oxygen generation

The decomposition of lipid hydroperoxides (LOOH) into peroxyl radicals is a potential source of singlet molecular oxygen ((1)O(2)) in biological systems. Recently, we have clearly demonstrated the generation of (1)O(2) in the reaction of lipid hydroperoxides with biologically important oxidants such as metal ions, peroxynitrite and hypochlorous acid. The approach used to unequivocally demonstrate the generation of (1)O(2) in these reactions was the use of an isotopic labeled hydroperoxide, the (18)O-labeled linoleic acid hydroperoxide, the detection of labeled compounds by HPLC coupled to tandem mass spectrometry (HPLC-MS/MS) and the direct spectroscopic detection and characterization of (1)O(2) light emission. Using this approach we have observed the formation of (18)O-labeled (1)O(2) by chemical trapping of (1)O(2) with anthracene derivatives and detection of the corresponding labeled endoperoxide by HPLC-MS/MS. The generation of (1)O(2) was also demonstrated by direct spectral characterization of (1)O(2) monomol light emission in the near-infrared region (lambda = 1270 nm). In summary, our studies demonstrated that LOOH can originate (1)O(2). The experimental evidences indicate that (1)O(2) is generated at a yield close to 10% by the Russell mechanism, where a linear tetraoxide intermediate is formed in the combination of two peroxyl radicals. In addition to LOOH, other biological hydroperoxides, including hydroperoxides formed in proteins and nucleic acids, may also participate in reactions leading to the generation (1)O(2). This hypothesis is currently being investigated in our laboratory.     

Chromosomal distribution of major rDNA and genome size variation in Belostoma angustum Lauck,B. nessimiani Ribeiro & Alecrim,and B. sanctulum Montandon (Insecta,Heteroptera, Belostomatidae)

Genetica - Known as "electric-light bugs", belostomatids potentially act as agents of biological control. The Belostoma genus has holokinetic chromosomes, interspecific variation in...     

Hybridization and polyploidization effects on LTR-retrotransposon activation in potato genome

Hybridization and polyploidization are major forces in plant evolution and potatoes are not an exception. It is proposed that the proliferation of Long Terminal Repeat-retrotransposons (LTR-RT) is related to genome reorganization caused by hybridization and/or polyploidization. The main purpose of the present work was to evaluate the effect of interspecific hybridization and polyploidization on the activation of LTR-RT. We evaluated the proliferation of putative active LTR-RT in a diploid hybrid between the cultivated potato Solanum tuberosum and the wild diploid potato species S. kurtzianum, allotetraploid lines derived from this interspecific hybrid and S. kurtzianum autotetraploid lines (ktz-autotetraploid) using the S-SAP (sequence-specific amplified polymorphism) technique and normalized copy number determination by qPCR. Twenty-nine LTR-RT copies were activated in the hybrid and present in the allotetraploid lines. Major LTR-RT activity was detected in Copia-27, Copia-12, Copia-14 and, Gypsy-22. According to our results, LTR-RT copies were activated principally in the hybrid, there was no activation in allotetraploid lines and only one copy was activated in the autotetraploid.

     

Effects of Ethanolic Extract of Cynara cardunculus (Artichoke) Leaves on Neuroinflammatory and Neurochemical Parameters in a Diet-Induced Mice Obesity Model

Neurochemical Research - This study aimed to evaluate the effect of Cynara cardunculus leaf ethanol extract on inflammatory and oxidative stress parameters in the hypothalamus, prefrontal cortex,...     

Reproductive biology of the lane snapper,Lutjanus synagris (Linnaeus 1758) (Perciformes,Lutjanidae), in the Maranhão continental shelf,Northeast of Brazil

Environmental Biology of Fishes - To clarify the reproductive activity of lane snapper, Lutjanus synagris, a total of 359 specimens of lane snapper were collected in partnership with an artisanal...