Assessing the ecological risks from the persistence and spread of feral populations of insect-resistant transgenic maize

One source of potential harm from the cultivation of transgenic crops is their dispersal, persistence and spread in non-agricultural land. Ecological damage may result from such spread if the abundance of valued species is reduced. The ability of a plant to spread in non-agricultural habitats is called its invasiveness potential. The risks posed by the invasiveness potential of transgenic crops are assessed by comparing in agronomic field trials the phenotypes of the crops with the phenotypes of genetically similar non-transgenic crops known to have low invasiveness potential. If the transgenic and non-transgenic crops are similar in traits believed to control invasiveness potential, it may be concluded that the transgenic crop has low invasiveness potential and poses negligible ecological risk via persistence and spread in non-agricultural habitats. If the phenotype of the transgenic crop is outside the range of the non-transgenic comparators for the traits controlling invasiveness potential, or if the comparative approach is regarded as inadequate for reasons of risk perception or risk communication, experiments that simulate the dispersal of the crop into non-agricultural habitats may be necessary. We describe such an experiment for several commercial insect-resistant transgenic maize events in conditions similar to those found in maize-growing regions of Mexico. As expected from comparative risk assessments, the transgenic maize was found to behave similarly to non-transgenic maize and to be non-invasive. The value of this experiment in assessing and communicating the negligible ecological risk posed by the low invasiveness potential of insect-resistant transgenic maize in Mexico is discussed.     

Nickel localization on tissues of hyperaccumulator species of Phyllanthus L. (euphorbiaceae) from Ultramafic Areas of Cuba

Two species of perennial Phyllanthus (Euphorbiaceae) (Phyllanthus orbicularis and Phyllanthus discolor, both endemic to ultramafic areas of Cuba, and their natural hybrid, Phyllanthus xpallidus) were selected for metal localization microanalysis. Different plant tissues were analyzed by X-ray fluorescence, inductively coupled plasma—atomic emission spectroscopy, and scanning electron microscopy coupled with an energy-dispersive X-ray probe. All of the studied taxa are nickel (Ni) hyperaccumulators and significant concentrations of this element were found in different leaf and stem tissues. The highest Ni content was found in the laticifer tubes, whereas leaf epidermis Ni content resulted to be much more relevant in terms of total metal storage. Calcium and magnesium were found more evenly distributed in leaf and stem tissues.     

Identifying the membrane proteome of HIV-1 latently infected cells

Profiling integral plasma membrane proteins is of particular importance for the identification of new biomarkers for diagnosis and for drug development. We report in this study the identification of surface markers by performing comparative proteomics of established human immunodeficiency virus-1 (HIV-1) latent cell models and parental cell lines. To this end we isolated integral membrane proteins using a biotin-directed affinity purification method. Isolated proteins were separated by two-dimensional gel electrophoresis and identified by matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) after in gel digestion. Seventeen different proteins were found to vary on the surface of T-cells due to HIV-1 infection. Of these proteins, 47% were integral membrane proteins, and 18% were membrane-associated. Through the use of complementary techniques such as Western blotting and fluorescent staining, we confirmed the differential expression of some of the proteins identified by MALDI-TOF including Bruton's tyrosine kinase and X-linked inhibitor of apoptosis. Finally, using phosphatidylinositol 3-kinase inhibitors and flavopiridol to inhibit Bruton's tyrosine kinase localization at the membrane and X-linked inhibitor of apoptosis protein expression, respectively, we showed that HIV-1 latently infected cells are more sensitive to these drugs than uninfected cells. This suggests that HIV-1 latently infected cells may be targeted with drugs that alter several pathways that are essential for the establishment and maintenance of latency.     

Regulation of phagocytic process of macrophages by noradrenaline and its end metabolite 4-hydroxy-3-metoxyphenyl-glycol. Role of α- and β- adrenoreceptors

The regulatory capacity of noradrenaline and its end metabolite 4-hydroxy-3-metoxyphenylglycol (HMPG) on the complete phagocytic process of macrophages were investigated. Either noradrenaline or HMPG did not modify adherence. However, 10^–12 M of noradrenaline stimulated the chemotaxis of macrophages, mainly mediated by -adrenergic receptors. In contrast, 10^–12 M of HMPG induced an opposed effect on this stage of the phagocytic process. To stimulate phagocytosis, it is necessary to employ a higher concentration (10^–5 M) of noradrenaline and this effect was blocked with either 10^–6 M propranolol or 10^–6 M phentolamine, and maintained by HMPG. Noradrenaline and HMPG did not modify the microbicide capacity of macrophages (measured by O₂ ^– production after phagocytosis). In conclusion, noradrenaline modulates the phagocytic process of macrophages, and this modulation is completed by HMPG, maintaining the phagocytic functions at physiologically optimal levels. Modulation of chemotaxis is mainly mediated by a-receptors and phagocytosis needs both - and -receptor-stimulation.     

Xanthophyllomyces dendrorhous for the industrial production of astaxanthin

Astaxanthin is a red xanthophyll (oxygenated carotenoid) with large importance in the aquaculture, pharmaceutical, and food industries. The green alga Haematococcus pluvialis and the heterobasidiomycetous yeast Xanthophyllomyces dendrorhous are currently known as the main microorganisms useful for astaxanthin production at the industrial scale. The improvement of astaxanthin titer by microbial fermentation is a requirement to be competitive with the synthetic manufacture by chemical procedures, which at present is the major source in the market. In this review, we show how the isolation of new strains of X. dendrorhous from the environment, the selection of mutants by the classical methods of random mutation and screening, and the rational metabolic engineering, have provided improved strains with higher astaxanthin productivity. To reduce production costs and enhance competitiveness from an industrial point of view, low-cost raw materials from industrial and agricultural origin have been adopted to get the maximal astaxanthin productivity. Finally, fermentation parameters have been studied in depth, both at flask and fermenter scales, to get maximal astaxanthin titers of 4.7 mg/g dry cell matter (420 mg/l) when X. dendrorhous was fermented under continuous white light. The industrial scale-up of this biotechnological process will provide a cost-effective method, alternative to synthetic astaxanthin, for the commercial exploitation of the expensive astaxanthin (about $2,500 per kilogram of pure astaxanthin).     

Auxin metabolism in mosses and liverworts

The plant hormone auxin (indole-3-acetic acid, IAA) is involved in the control of many phenomena during plant development. By characterizing steady-state free and conjugated IAA levels using a stable isotope dilution method coupled with gas chromatography- selected ion monitoring- mass spectrometry, this paper provides a detailed characterization of IAA metabolism in five liverworts, four mosses, and two tracheophytes. Long-term IAA conjugation patterns were monitored by incubating actively growing tissue with (14)C-IAA and then analyzing the de novo synthesis of IAA conjugates with radioimaging techniques. The liverworts, mosses, and tracheophytes can be differentiated by the total amount of IAA metabolites, the proportion of free and conjugated IAA, the chemical nature of their IAA conjugates, and the rates of IAA conjugation. Our tentative conclusion is that the liverworts appear to employ a biosynthesis-degradation strategy for the regulation of free IAA levels, in contrast to the conjugation-hydrolysis strategy apparently used by the mosses and tracheophytes. Such alternative metabolic strategies may have profound implications for macroevolutionary processes in these plant groups.     

Abnormal cell cycle regulation in primary human uveal melanoma cultures

Uveal malignant melanoma is the most frequent primary intraocular tumor in adult humans. The cellular events leading to neoplasic transformation of normal uveal melanocytes are not well known when compared to other cancers. In this study, we investigated the role of G1 and G1/S regulatory proteins of the cell cycle in human uveal melanoma (UM) primary cell cultures, since these proteins are common targets in tumor development. Further, freshly established and characterized tumor cells are a better model for in vitro studies when compared to cell lines established long ago. Human primary cell cultures from eight different UM were established, as well as one primary culture from rhesus uveal normal melanocytes (UNM). Primary human UM cultures were characterized by a low establishment and growing rate. From four successful cultures, three showed a high expression of cyclin D1, cyclin E, p16NK4A, and p27KIP1 with no variations in cyclin A, cyclin-dependent kinase 2 (CDK2), and CDK4. Interestingly, in one of the cultured tumors, tumor suppressor protein retinoblastoma (Rb) did not bind E2F despite the fact that Rb was found in its hypophosphorylated form. No mutations in either RB1 or the Rb-binding pocket of E2F-1 were detected. Furthermore, we identified seven proteins co-immunoprecipitating with Rb in this tumor, including Lamin A/C and six proteins not previously reported to bind Rb: Hsc70, high mobility group protein 1 (HMG-1), hnRPN, glyceraldehyde 3 phosphate dehydrogenase (G3PDH), EF-1, and EF-2. Our results indicate that the overexpression of cyclins D1/E and CDKIs p16 and p27, together with a deregulation of the Rb/E2F pathway, may be implicated in the development of human UM.