Rhizosphere-induced selenium precipitation for possible applications in phytoremediation of se polluted effluents

Two bacterial isolates were obtained in axenic culture from the rhizosphere soil of Astragalus bisulcatus, a legume able to hyperaccumulate selenium. Both strains resulted of particular interest for their high resistance to the toxic oxyanion SeO3(2-) (selenite, Se(IV)). On the basis of molecular and biochemical analyses, these two isolates were attributed to the species Bacillus mycoides and Stenotrophomonas maltophilia, respectively. Their capability in axenic culture to precipitate the soluble, bioavailable and highly toxic selenium form selenite to insoluble and relatively non-toxic Se(0) (elemental selenium) was evaluated in defined medium added with 0.2 or 0.5 mM Se(IV). Both strains showed to completely reduce 0.2 mM selenite in 120 h, while 0.5 mM Se(IV) was reduced up to 67% of the initial concentration by B. mycoides and to about 50% by S. maltophilia in 48 h. Together in a dual consortium, B. mycoides and S. maltophilia increased the kinetics of selenite reduction, thus improving the efficiency of the process. A model system for selenium rhizofiltration based on plant-rhizobacteria interactions has been proposed.     

Laser pressure catapulting (LPC): optimization LPC-system and genotyping of colorectal carcinomas

Genotype analysis is becoming more and more useful in clinical practice, since specific mutations in tumors often correlate with prognosis and/or therapeutic response. Unfortunately, current molecular analytical techniques often require time-consuming and costly steps of analysis, thus making their routine clinical use difficult. Moreover, one of the most difficult problems arising during tumor research is that of their cell heterogeneity, which depends on their clear molecular heterogeneity. SSCP analysis discriminates by means of aberrant electrophoresis migration bands, mutated alleles which may represent as little as 15-20% of their total number. Nevertheless, in order to identify by sequencing the type of alteration revealed by this technique, only the mutated allele must be isolated. The advent of laser microdissection is a procedure which easily solves these problems of accuracy, costs, and time. The aims of this study were to perfect the system of laser pressure catapulting (LPC) laser microdissection for the assessment of the mutational status of p53 and k-ras genes in a consecutive series of 67 patients with colorectal carcinomas (CRC), in order to compare this technique with that involving hand-dissection and to demonstrate that since the LPC system guarantees more accurate biomolecular analyses, it should become part of clinical routine in this field. The LPC-system was perfected with the use of mineral oil and the LPC-membrane. To compare the techniques of hand- and LPC-microdissection, alcohol-fixed, paraffin-embedded tissue from 67 cases of CRC were both hand- and laser-microdissected. In either case, dissected samples were analyzed by SSCP/sequencing and direct sequencing for k-ras and p53 gene mutations. LPC-microdissection made it possible to pick up mutations by direct sequencing or SSCP/sequencing, whereas hand-microdissection mutations were identified only by means of SSCP followed by sequencing; direct sequencing did not reveal any mutation. In the 67 patients examined by either method, 36% (24/67) showed p53 mutations, 32 of which identified. Seventy-eight percent (25/32) were found in the conserved areas of the gene, while 12% (4/32) were in the L2 loop, 50% (16/32) were in the L3 loop, and 12% (4/32) in the LSH motif of the protein. Moreover, of the 67 cases examined, 40% (27/67) showed mutations in k-ras, with a total of 29 mutations identified. Of these, 14 (48%) were found in codon 12 and 15 (52%) in codon 13. The modifications which we brought to the LPC system led to a vast improvement of the technique, making it an ideal substitution for hand-microdissection and guaranteeing a considerable number of advantages regarding facility, accuracy, time, and cost. Furthermore, the data obtained from the mutational analyses performed confirm that the LPC system is more efficient and rapid than hand-microdissection for acquiring useful information regarding molecular profile and can therefore be used with success in clinical routine.     

IL-7 administration alters the CD4:CD8 ratio, increases T cell numbers, and increases T cell function in the absence of activation

IL-7 is vital for the development of the immune system and profoundly enhances the function of mature T cells. Chronic administration of IL-7 to mice markedly increases T cell numbers, especially CD8(+) T cells, and enhances T cell functional potential. However, the mechanism by which these effects occur remains unclear. This report demonstrates that only 2 days of IL-7 treatment is needed for maximal enhancement of T cell function, as measured by proliferation, with a 6- to 12-fold increase in the proportion of CD4(+) and CD8(+) T cells in cell cycle by 18 h of ex vivo stimulation. Moreover, a 2-day administration of IL-7 in vivo increases basal proliferation by 4- and 14-fold in CD4(+) and CD8(+) T cells, respectively. These effects occur in the absence of cytokine production, increases in most activation markers, and changes in memory markers. This enhanced basal proliferation is the basis for the increase in T cell numbers in that IL-7 induces an additional 60% and 85% of resting CD4(+) and CD8(+) T cells, respectively, to enter cell cycle in mice given IL-7 for 7 days. These results demonstrate that in vivo administration of IL-7 increases T cell numbers and functional potential via a homeostatic, nonactivating process. These findings may suggest a unique clinical niche for IL-7 in that IL-7 therapy may increase T cell numbers and enhance responses to specific antigenic targets while avoiding a general, nonspecific activation of the T cell population.     

Glutamate-Glutamine Cycle and Aging in Striatum of the Awake Rat: Effects of a Glutamate Transporter Blocker

This study investigated the effects of aging on the actions of a specific glutamate reuptake blocker, L-trans-pyrrolidine-2, 4-dicarboxylic acid (PDC), in extracellular glutamate and glutamine in striatum of the awake rat. Microdialysis experiments were performed on young (2–3 months), middle-aged (12–14 months), aged (27–32 months) and very aged (37 months) male Wistar rats. Local infusion of PDC (1–4 mM) in striatum increased the dialysate concentration of glutamate and decreased dialysate concentration of glutamine in all the age-groups. In young rats, decreases of dialysate glutamine were correlated with increases of dialysate glutamate. The same profile glutamine/glutamate as in young rats was found in middle-aged, aged and very aged rats, which suggests that the action of glutamate on the glutamate-glutamine cycle in striatum of the awake rat is not modified as a consequence of aging. We also found a significant correlation between the increases of glutamate produced by PDC and the basal dialysate concentration of glutamine, a relationship that did show a significant change with age. Although the significance of this latter finding remains to be elucidated, it may be important to understand the changes in glutamate-glutamine cycle during aging.     

Nebulin regulates actin filament lengths by a stabilization mechanism

Efficient muscle contraction requires regulation of actin filament lengths. In one highly cited model, the giant protein nebulin has been proposed to function as a molecular ruler specifying filament lengths. We directly challenged this hypothesis by constructing a unique, small version of nebulin (mini-nebulin). When endogenous nebulin was replaced with mini-nebulin in skeletal myocytes, thin filaments extended beyond the end of mini-nebulin, an observation which is inconsistent with a strict ruler function. However, under conditions that promote actin filament depolymerization, filaments associated with mini-nebulin were remarkably maintained at lengths either matching or longer than mini-nebulin. This indicates that mini-nebulin is able to stabilize portions of the filament it has no contact with. Knockdown of nebulin also resulted in more dynamic populations of thin filament components, whereas expression of mini-nebulin decreased the dynamics at both filament ends (i.e., recovered loss of endogenous nebulin). Thus, nebulin regulates thin filament architecture by a mechanism that includes stabilizing the filaments and preventing actin depolymerization.     

Sexually dimorphic phrase organization in the song of the indris (Indri indri)

Animal acoustic communication often takes the form of complex sequences, composed of multiple distinct acoustic units, which can vary in their degree of stereotypy. Studies of sequence variation may contribute to our understanding of the structural flexibility of primates' songs, which can provide essential ecological and behavioral information about variability at the individual, population, and specific level and provide insights into the mechanisms and drivers responsible for the evolutionary change of communicative traits. Several methods have been used for investigating different levels of structural information and sequence similarity in acoustic displays. We studied intra and interindividual variation in the song structuring of a singing primate, the indri (Indri indri), which inhabits the montane rain forests of Madagascar. Indri groups emit duets and choruses in which they combine long notes, short single units, and phrases consisting of a variable number of units (from two to six) with slightly descending frequency. Males' and females' contributions to the song differ in the temporal and frequency structure of song units and repertoire size. We calculated the similarity of phrase organization across different individual contributions using the Levenshtein distance, a logic distance that expressed the minimum cost to convert a sequence into another and can measure differences between two sequences of data. We then analyzed the degree of similarity within and between individuals and found that: (a) the phrase structure of songs varied between reproductive males and females: female structuring of the song showed a higher number of phrases if compared to males; (b) male contributions to the song were overall more similar to those of other males than were female contributions to the song of other females; (c) male contributions were more stereotyped than female contributions, which showed greater individual flexibility. The picture emerging from phrase combinatorics in the indris is in agreement with previous findings of rhythmic features and song repertoire size of the indris, which also suggested that female songs are potentially less stereotyped than those of males.     

Age and growth differences in two populations of the edible marine gastropod Buccinanops globulosus

Buccinanops globulosus is an edible marine gastropod that is being captured by artisanal fishermen without management regulations. As basic knowledge on population features is required in case a sustained commercial exploitation of this species is established, we estimated and compared the age and growth of B. globulosus in two populations separated by 16?km, inhabiting similar physical environments but different anthropic influence. Our results, based on stable oxygen isotope analysis and best fitted models by likelihood ratio tests, detected differences in age and growth between both samplings. Maximum shell marks suggest one year difference between populations. Richards was chosen as the best fitting model for both sampling sites and significant differences were observed between them. Human activities could be causing the age reduction among other irreversible effects on the population under anthropic influence. This should be considered when developing sustainable management regulations for this fishery resource, especially those based on shell/age size.