Aggregation of recombinant human interferon alpha 2b in solution: Technical note

Sodium phosphate buffer increased the aggregation of rhIFN-α2b in the range of 1.55 to 1.810³ day⁻¹, as determined by SDS/PAGE under reduced and nonreduced conditions. In contrast, sodium citrate buffer decreased the aggregation rate of this cytokine, as compared with those samples in sodium phosphate buffer. Results from sodium citrate-phosphate buffer were very similar to those obtained with sodium citrate solutions. On the other hand, EDTA Na₂×2H₂O reduced the aggregation rate of rhIFN-α2b, showing an aggregation kinetic constant in the range of 0.52 to 0.75×10³ day⁻¹. Polysorbates 20 and 80 were less effective than the chelating agent in preventing this degradation pathway.     

Plant biocommunicators: their phytotoxicity, degradation studies and potential use as herbicide models

The development of new bioactive molecules with potential application in pharmacology and agriculture by using natural products as templates has been a widely used approach in the recent years. Focusing our attention in phytochemicals with potential application in agriculture, allelochemicals (natural plant toxins) have been deeply researched with the main purpose of finding phytotoxic substances to use as new herbicidal templates. The development of new analytical methodologies, improved bioassay techniques and a complete understanding of the allelopathic phenomenon will provide new tools for natural herbicide models development, in the context of the new approaches to integrated pest management. A deeper knowledge of the release and assimilation of allelochemicals, and the degradation phenomena associated to them will aid to discover new chemical structures with potential utility, in addition to a better understanding on the ecological interactions mediated by phytochemicals. The research on these topics, made with promising allelochemicals such as benzoxazinones and their degradation derivatives, the improvements on analytical design, the degradation mechanisms elucidation and the novel bioassay techniques recently developed, are revised herein.     

Effects of methamidophos on sediment processing and body mass of Capitella sp. Y from Estero del Yugo, Mazatlán, Mexico

The cosmopolitan species-complex Capitella, a deposit-feeding polychaete, is widely used as an indicator of organic pollution and plays an important role in sewage waste cycling in marine and estuarine ecosystems. The organophosphorous insecticide methamidophos is currently employed in agriculture fields to control insect infestations. Its occurrence could pose a hazard to infauna. A bioassay to investigate the effects of exposing Capitella sp. Y to sediment spiked with methamidophos (0.008, 0.016, 0.032, 0.064, 0.130 and 0.260 mg/g dry wt sediment) is described. Increasing methamidophos concentrations significantly reduced faecal pellet production and body mass. Some specimens exhibited morphological abnormalities and behaviour changes, which could be attributed to toxic effects of methamidophos not severe enough to stop feeding activity. Results using Capitella sp. Y suggest that methamidophos could affect the rate of sediment processing by polychaetes or other benthic invertebrates in zones subjected to the influence of such insecticide.     

Cat odor causes long-lasting contextual fear conditioning and increased pituitary-adrenal activation, without modifying anxiety

A single exposure to a cat or cat odors has been reported by some groups to induce contextual and auditory fear conditioning and long-lasting changes in anxiety-like behaviour, but there is no evidence for parallel changes in biological stress markers. In the present study we demonstrated in male rats that exposure to a novel environment containing a cloth impregnated with cat fur odor resulted in avoidance of the odor, lower levels of activity and higher pituitary-adrenal (PA) response as compared to those exposed to the novel environment containing a clean cloth, suggesting increased levels of stress in the former animals. When re-exposed 9 days later to the same environment with a clean cloth, previously cat fur exposed rats again showed avoidance of the cloth area and lower levels of activity, suggesting development of contextual fear conditioning, which again was associated with a higher PA activation. In contrast, unaltered both anxiety-like behaviour and PA responsiveness to an elevated plus-maze were found 7 days after cat odor exposure. It is concluded that: (i) PA activation is able to reflect both the stressful properties of cat fur odor and odor-induced contextual fear conditioning; (ii) development of cat odor-induced contextual fear conditioning is independent of the induction of long-lasting changes in anxiety-like behaviour; and (iii) greater PA activation during exposure to the odor context is not explained by non-specific sensitization of the PA axis caused by previous exposure to cat fur odor.     

The Functional Quality of Soluble Recombinant Polypeptides Produced in Escherichia coli Is Defined by a Wide Conformational Spectrum

We have observed that a soluble recombinant green fluorescent protein produced in Escherichia coli occurs in a wide conformational spectrum. This results in differently fluorescent protein fractions in which morphologically diverse soluble aggregates abound. Therefore, the functional quality of soluble versions of aggregation-prone recombinant proteins is defined statistically rather than by the prevalence of a canonical native structure.     

Guatemalan plants extracts as virucides against HIV-1 infection

Prevention methods to avoid transmission of pathogens, including HIV, are crucial in the control of infectious diseases, not only to block epidemic spread but to avoid long-term treatments leading to emergence of resistances and drug associated side effects. Together with vaccine development, the discovery of new virucidal agents represents a research priority in this setting. In the screening of new compounds with antiviral activity, three Guatemalan plant extracts from Justicia reptans, Neurolaena lobata and Pouteria viridis were evaluated with a classic antiviral assay and were found to inhibit HIV replication. This activity was corroborated by an original recombinant virus assay, leading us to perform a deeper study of the virucidal activity. Active fractions were non-toxic in vitro and also inhibited other enveloped viruses. Moreover, these fractions were able to inhibit the transfer of HIV from dendritic cells (DCs) to lymphocytes, that represents the main way of HIV spread in vivo.     

Synthesis, structure and biological activity of a new and efficient Cd(II)–uracil derivative complex system for cleavage of DNA

The new complex formed by Cd(II) and the 1:2 Schiff-base-type ligand 2,6-bis[1-(4-amino-1,2,3,6-tetrahydro-1,3-dimethyl-2,6-dioxopyrimidin-5-yl)imino]ethylpyridine (DAPDAAU) has been chemically and structurally characterized by X-ray diffraction: the ion Cd(II) is surrounded by six nitrogen atoms from two DAPDAAU ligands which coordinates each one in a tridentate fashion through the pyridine ring (N1) and both azomethine nitrogen atoms (N5). The interaction of the Cd(II) complex (compound I) with calf-thymus DNA as observed by circular dichroism spectroscopy suggests the initial unwinding of the DNA double helix strongly depends on increasing incubation times and metal-to-nucleic acid molar ratios. Electrophoretic experiments indicate that the cadmium complex induces cleavage of the plasmid pBR322 DNA to give ulterior nicking and shortening of this molecule, as a result of the complex binding to DNA, resulting in the conclusion that compound I behaves as a chemical nuclease. Cytotoxic activity of the Cd(II) complex against selected different human cancer cell lines is specific and increases with increasing concentration of the metal compound; this fact indicates the potential antitumor character of the complex. When the culture medium is supplemented with compound I, a remarkable inhibition of the growing cell is observed, important cell degeneration appears before 48 h and abundant precipitates are formed that correspond to cell residues and denatured proteins. Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

Assessing effects of fishing prohibition on Posidonia oceanica seagrass meadows in the Marine Natural Reserve of Cerbère-Banyuls

The potential of alleviated fishing pressure measures established at the Marine Natural Reserve of Cerbère-Banyuls to affect phenological characters of P. oceanica, the main canopy-forming seagrass, was studied. Our results show differences in some leaf parameters between meadows under fishing prohibition measures compared to those without. In addition shallow P. oceanica meadows inside MPAs had lower non-structural carbohydrate content, yet are able to maintain themselves and, moreover, with an increased density. On the other hand, sexual reproduction was reduced inside protected areas.