Scielo RSS <![CDATA[Electronic Journal of Biotechnology]]> http://www.scielo.cl/rss.php?pid=0717-345820060002&lang=es vol. 9 num. 2 lang. es <![CDATA[SciELO Logo]]> http://www.scielo.cl/img/en/fbpelogp.gif http://www.scielo.cl http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582006000200001&lng=es&nrm=iso&tlng=es <![CDATA[<B>Recent developments in biotech industry outside of the USA and Western Europe</B>: <B>Report from BIO 2005</B>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582006000200002&lng=es&nrm=iso&tlng=es The BIO 2005 international convention is the largest gathering of the biotech industry in the world. This year it was held on June 19-22 inside the behemoth Convention Center in downtown Philadelphia, bringing together 18,730 executives, investors, consultants, lawyers, politicians, scientists, and dreamers from 56 countries. More than 500 media representatives covered the event. Biotechnology research and findings presented by countries outside the USA and Western Europe has begun to make a significant impact on these annual BIO gatherings. The achievements of some of these countries are briefly reviewed. <![CDATA[<b>Biosorption of uranium from aqueous solutions by nonliving biomass of marinealgae <i>Cystoseira indica </i></b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582006000200003&lng=es&nrm=iso&tlng=es Biosorption of heavy metals can be an effective process for the removal and recovery of heavy metal ions from aqueous solutions. In this paper uranium biosorption by protonated, Ca-pretreated and non-pretreated Cystoseira indica algae biomass was investigated in a batch system. The results of the kinetic studies showed that the sorption of uranium on protonated and non-pretreated biomass followed pseudo-second order kinetics. The effect of pH on the equilibrium uranium sorption capacity of Cystoseira indica exhibited that highest uptake occurred at pH 4 at a solution with 350 mg/l uranium concentration. At various initial uranium concentrations from 50 to 1000 mg/l, batch sorption equilibrium at 30&ordm;C was reached within 3 hrs and the sorption isotherms were interpreted in terms of the Langmuir and Freundlich models. Equilibrium data fitted very well to Langmuir model for all studied forms of Cystoseira indica algae. The Freundlich isotherm cannot fit as well as the Langmuir model the equilibrium data of protonated and non-pretreated Cystoseira indica algae. The maximum uranium adsorption capacity on the Ca-pretreated, protonated and non-pretreated Cystoseira indica algae predicted by Langmuir isotherm at pH 4 and 30&ordm;C was 454.5, 322.58 and 224.67 mg/g respectively. <![CDATA[<b>Biotransformation of anthracene and fluoranthene by<i> Absidia fusca </i>Linnemann</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582006000200004&lng=es&nrm=iso&tlng=es A strain of Absidia fusca was isolated from a pesticide-contaminated soil (Annaba, Algeria). The biotransformation capability of this strain towards two polycyclic aromatic hydrocarbons (PAHs): anthracene and fluoranthene was compared to that exhibited by another strain of A. fusca isolated from a non-contaminated milieu and considered as a control. The results obtained were statistically analyzed and showed that the strain isolated from the contaminated soil was more efficient than the control to remove anthracene from the medium, during all the kinetics (90% removed versus 45% after 24 hrs). Concerning fluoranthene, the amount removed by both strains was very high during the first 24 hrs however the control strain was slightly more efficient (94% versus 89%) while the results were similar for the two strains during the rest of the kinetics. This study reveals for the first time the potential interest of the species A. fusca for the bioremediation of PAHs. <![CDATA[<b>Expression of <i>Bacillus thuringiensis</i> insecticidal protein gene in transgenic oil palm</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582006000200005&lng=es&nrm=iso&tlng=es Oil palm, like all other crops, is susceptible to attack from several insect pests causing significant reduction in productivity. In the past, cry genes from Bacillus thuringiensis have been reported to be effective in conferring resistance towards insect pests in crops such as corn and rice. One of the advantages of these toxin proteins is their specificity towards certain harmful insects. A rapid and efficient method was developed for the transformation and evaluation of CryIA(b) expression in oil palm. A recombinant vector was introduced into immature embryos (IEs) of oil palm via the biolistic method. More than 700 putative transformed IEs from independent transformation events were generated. Transient transformation efficiency of 81-100 % was achieved. We found that pre-treatment of target tissues with phytohormones is essential for increasing the transformation efficiency. This finding could enable higher transformation rate in oil palm that was previously difficult to transform. PCR analysis further confirmed the presence of the CryIA(b) in the transformed tissues. Expression of CryIA(b) from PCR-positive samples was further confirmed using a rapid gene expression detection system. This novel and rapid detection system could serve as a good opportunity to analyze the impact of transgenes upon transfer to the new environment, especially for crops with long generation cycle, such as oil palm. <![CDATA[<b>Identification of phase relative genes in tetrasporophytes and female gametophytes of <i>Gracilaria/Gracilariopsis lemaneiformis </i>(Gracilariales, Rhodophyta)</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582006000200006&lng=es&nrm=iso&tlng=es Genes differentially expressed between tetrasporophytes and female gametophytes of Gracilaria/Gracilariopsis lemaneiformis were isolated by suppression subtractive hybridization (SSH) and screened by dot-blot macro-arrays. Different expression profiles of selected clones based on the results of dot-blot macro-arrays were verified using virtual Northern blots. Totally, 14 phase relative cDNAs had been isolated and sequence identified. Among them, seven cDNAs were respectively homologous to crucial metabolic enzymes, Rab GTPase, RP42 homolog, and two hypothetical proteins, while the rest did not have significant hits in the databases examined. The results of virtual Northern blots revealed that 11 cDNAs were differentially expressed between the two samples, including 7 genes up-regulated in tetrasporophytes, 1 expressed exclusively in tetrasporophytes and 3 up-regulated in female gametophytes. By densitometric analysis relative to GAPDH, 8 cDNAs increased 1.3-4.2 fold and 3 decreased about 0.4-0.7 fold in tetrasporophytes compared to female gametophytes. The present study provides the first insight into genes that may involve in phase differentiation in G. lemaneiformis. <![CDATA[<b>Production of polyclonal antisera to manganese superoxide dismutase expressed in downy mildew resistant pearl millet and its application for immunodiagnosis</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582006000200007&lng=es&nrm=iso&tlng=es Level of superoxide dismutase (SOD) in the seedlings of downy mildew resistant pearl millet genotype (IP 18293) increased 3-fold upon inoculation with Sclerospora graminicola. Mn-SOD was purified from pearl millet by ion-exchange and gel filtration chromatography. Polyclonal antibody was raised in rabbit against Mn-SOD of pearl millet. Anti-Mn SOD had an antibody titer of 1:20,000. ELISA results revealed a 1.5-fold increase in pure Mn-SOD preparation compared to the crude preparation. The antibody reactivity as detected by ELISA revealed that Mn-SOD is higher at 4 hrs post-inoculation in resistant pearl millet seedlings. The reactivity also showed the Mn-SOD is more in roots of inoculated resistant seedlings. SOD reactivity was also determined by DIBA (Dot-immunobinding assay). The results suggested that the Mn-SOD antibody reacted more strongly with crude SOD of the inoculated resistant seedlings than inoculated resistant seedlings. Western blot analysis revealed the induction of 35 kDa SOD protein in the resistant genotype. Its appearance on western blot coincided with high SOD activity. Immunolocalization experiments showed that SOD protein was abundant in the vascular bundles. The antibody produced to Mn-SOD was specific as judged by ELISA, DIBA, western blot and immunofluorescence assays. The work described here investigates the possibility of using the serological techniques to assess the reactivity of antibody with the SOD antigen. <![CDATA[<B>Protective effect of an antimicrobial peptide from <I>Mytilus edulis chilensis</I> expressed in <EM>Nicotiana tabacum </EM>L.</B>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582006000200008&lng=es&nrm=iso&tlng=es A "defensin-like" antibacterial peptide from Mytilus edulis chilensis, was sub-cloned into a binary vector for expression in plant tissues. The resulting new clone was electroporated into A. tumefaciens to transform tobacco plants. The presence of the construct in transgenic tobacco lines was demonstrated through RT-PCR, Northern and Western blots. Transformed positive plants were selected and grown for challenging. Tobacco leaves were infiltrated with Pseudomonassyringae pv. syringae and visual lesions determined at different times post-exposure. Of seven plants exposed, four gave variable protection up to seven days post-infection while one of them appears to be fully protected. These results suggest that defensin-like antimicrobial peptides from molluscs are a good source to provide resistance of tobacco plants to Pseudomonassyringae pv. syringae. <![CDATA[Recovery of lead and cadmium ions from metal-loaded biomass of wild cocoyam (<I>Caladium bicolor)</I> using acidic, basic and neutral eluent solutions]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582006000200009&lng=es&nrm=iso&tlng=es The effects of acidic, basic and neutral reagents on the recovery of Pb2+ and Cd2+ from metal-loaded biomass of wild cocoyam (C. bicolor) were investigated by eluting the biomass in five successive cycles using 0.01 M HCl, 0.1 M HCl, 0.01 M NaOH, 0.1 M NaOH and distilled water at different contact times. The data showed that the ease of metal ion recovery from metal -loaded biomass by the eluent solutions is of the order 0.01 M HCl > 0.1 M HCl > 0.01 M NaOH > 0.1 M NaOH > distilled water. Over 94% Pb2+ and 74% Cd2+ of the initially adsorbed metals were recovered by 0.01 M HCl, while < 20% of both metals was recovered by basic reagent. Distilled water recovered less than 9% of both metal ions from the biomass. Macroscopic changes were also observed as the concentration of recovery reagent increased. This study has demonstrated that the selection of a recovery reagent for metal ions on a biomaterial should give consideration to the reusability of the biomass. <![CDATA[<B>Genetic engineering applications in animal breeding</B>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582006000200010&lng=es&nrm=iso&tlng=es This paper discusses the use of genetic engineering applications in animal breeding, including a description of the methods, their potential and current uses and ethical issues. Genetic engineering is the name of a group of techniques used to identify, replicate, modify and transfer the genetic material of cells, tissues or complete organisms. Important applications of genetic engineering in animal breeding are: 1) Marker-assisted selection (MAS). The objective of this technology is to increase disease resistance, productivity and product quality in economically important animals by adding information of DNA markers to phenotypes and genealogies for selection decisions. 2) Transgenesis, the direct transfer of specific genes/alleles between individuals, species, or even Kingdoms, in order to change their phenotypic expression in the recipients. Compared to the 'traditional' improvement techniques based on phenotypic information only, these gene-by-gene techniques allow theoretically a more complete management of animal genomes for animal breeding. In spite of high expectations and new technical developments, its actual efficiency is not always high, as they require a thorough knowledge of functional genomics, and pose additional technical, economical and ethical problems. The possible role for cloning adult animals in breeding is also discussed. <![CDATA[<B>Improved affinity selection using phage display technology and off-rate based selection</B>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582006000200011&lng=es&nrm=iso&tlng=es Flow systems such as a BIAcore biosensor can be very efficient tools to isolate high affinity antibody fragments from affinity matured phage display libraries. Here we show that using flow based selection, we can readily isolate a variant with a 35-fold higher affinity, especially with a 7 fold better off-rate, compared to the parent clone after only a single round of selection from a second generation affinity matured phage display library. The flow system represents a fast method to isolate affinity improved antibody fragments and can be particularly useful for isolating antibodies to antigens that have poor solubility, are toxic to the host cell, or prone to aggregation. <![CDATA[<B>Silanol - A novel class of antimicrobial agent</B>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582006000200012&lng=es&nrm=iso&tlng=es Recently, a significant amount of attention has been directed toward development of novel classes of biocides because of the potential for microbial contamination and infection risks to military personnel and in the general population. We have recently discovered a new and unexpected class of powerful biocides based upon compounds derived through simple chemistry from silicone intermediates, "silicon alcohols" called, silanols. One example is trialkylsilanols, R3SiOH. Antimicrobial tests were carried out against Gram-negative bacterium, Escherichia coli, and Gram-positive, Staphylococcus aureus, with silanols, t-butanol, and siloxanes. Trialkylsilanols were very effective biocides against Escherichia coli and Staphylococcus aureus. The number of viable bacteria reduced was more than eight orders of magnitude with silanol treatments. Triethylsilanol, in particular, exhibited a strong antimicrobial effect at a very low concentration within 10 min. These novel biocide silanols can be prepared from low cost intermediates derived from the commercial processesassociated with the silicone industry. Silanols are considered environmentally benign because of their transitory nature and ultimate conversion to CO2, SiO2, and H2O.