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A total of 36 microsatellites (SSR) markers were used to analyze the genetic diversity of 163 accessions of cultivated cassava (Manihot esculenta Crantz), 94 accessions of them from the Cuban Cassava Germplasm Collection and 69 genotypes from different countries and conserved at the International Center for Tropical Agriculture (Colombia). This study was carried out to determine genetic diversity within and between all accessions to promote their better use and conservation strategies. Thirty-four of those markers were used for the genetic diversity study based on their higher polymorphism. The Cuban cultivars showed the highest average allele number per loci with 5.8 and 100% of the loci were polymorphic, as well as those from Guatemala. The average proportion of individual heterozygocity observed (HO) was high (0.5918 ± 0.0351), while the highest HO rates were observed in groups of genotypes from Cuba (0.6016) and Tanzania (0.6459). The total heterozygocity (HT) was high (0.6538 ± 0.1770), but only 7.4% (GST = 0.0740 ± 0.0377) was due to differences between the five countries studied. Genetic differentiation coefficients (estimated by F-statistics) were low to moderate (FST > 0.04) and 17 unique alleles with low frequency were found in Cuban cultivars. The results provide the first molecular characterization of Cuban cassava genotypes and showed a wide diversity among landraces from Cuba. Application of this valuable information can be used for genetic diversity conservation and genotype identification studies for the genetic breeding program of cassava.

After 10 years of evaluation in different locations with high levels of incidence of disease, a group of sugarcane somaclones derived from callus tissues was selected for eyespot resistance. Resistance evaluations of four somaclones were performed under field and laboratory conditions. The results confirmed the superiority of two somaclones, one resistant and one tolerant to eyespot disease. Restriction analysts of mitochondrial DNA revealed that the two somaclones had a different DNA organization which distinguished them both from each other and from the donor plant, the restriction profile was similar however to that of the resistant control done. Restriction patterns of a third somaclone, also resistant, were similar to those of the donor plant. Differences among the somaclones were also evident when using a maize ribosomal DNA probe. [ABSTRACT FROM AUTHOR]

El desarrollo de una sociedad sustentable es una de las metas prioritarias de la Industria Básica (MINBAS), lo que implica que sus producciones no deben realizarse a cualquier costo económico ni ambiental. Los procesos biotecnológicos aplicados a la minería son una opción para los paises en desarrollo. La biolixiviación es una tecnología sustentable y promete ser una alternativa atractiva para la Industria del Níquel Cubana no sólo para la extracción del níquel, sino también para cobalto, manganeso, hierro y otros elementos metálicos. El número de artículos científicos y patentes publicadas en la literatura internacional sobre la biolixiviación de sulfuros es numeroso y supera con creces a las publicaciones referentes a menas no sulfurosas, como las de lateritas. En este caso, se aprovecha la capacidad de los hongos filamentosos de producir y excretar ácidos orgánicos al ambiente. Estos ácidos disuelven los metales pesados contenidos en la matriz del mineral por desplazamiento directo de ellos. En la literatura internacional ha sido informado Penicillium simplicissimum (Bosecker, 1989) como el hongo más activo para la biolixiviación de minerales oxidados. En el presente trabajo se informa la susceptibilidad de la serpentinita y el escombro laterítico del depósito Punta Gorda (Moa) al ser tratada mediante un proceso biotecnológico. De un total de 63 cepas fúngicas se seleccionó un grupo con capacidad de síntesis de ácido cítrico. De estas, 49 correspondieron a aislamientos cubanos de diferentes ecosistemas. La recuperación de cobalto (60%-70%) y manganeso (> 90%) fue superior con una cepa autóctona de Aspergillus niger que con Penicillium simplcissimu. El medio de cultivo y la selección de la cepa son factores determinantes en la biolixiviación y su eficiencia dependerá de características genéticas que influyen sobre la producción de los bioácidos. [ABSTRACT FROM AUTHOR]

The objective of this work was to evaluate the existing diversity degree in 23 Leucaena accessions, regarding the morphoagronomic and isoenzymatic characteristics. Five species of this genus were included (L. leucocephala, L. lanceolata, L. diversifolia, L. macrophylla and L. esculenta), in addition to the commercial cultivars. The following aspects were evaluated: plant height, number of branches, stem diameter, performance of the phenological flowering and fructification patterns, number of pinnae per leaf and of pinnules per pinna, among others. Besides the electrophoretic analyses peroxidases (Prx), α- and β- esterases (Est), malate dehydrogenase (Mdh) and alcohol dehydrogenase (Adh) were conducted. The accessions fulfilled the predetermined selection criteria regarding the morphoagronomic characteristics, although not in the same time. In this sense, L. leucocephala cv. Cunningham, cv. Peru, CIAT-9119, CIAT-9438, CIAT-751, CIAT-7988, CIAT-7384, CIAT-7929, CIAT-17480, cv. Ipil-Ipil and cv. CNIA-250; L. lanceolata CIAT-17255 and CIAT-17501, and L. diversifolia CIAT-17270, stood out. The existence of genetic variability within the collection could be detected. The isoenzymatic systems (esterases and peroxidases) turned out to be polymorphic in the studied sample, mainly esterases. On the other hand, the analysis of genetic diversity allowed differentiating L. leucocephala more clearly as compared to the other studied species, although no better discrimination was made within the species. [ABSTRACT FROM AUTHOR]

The identification of novel genes related to biotic and abiotic stress in Nicotiana tabacum L. can contribute to the genetic improvement of plants around the world. The aim of this research was to identify novel genes in tobacco varieties, as well as the molecular characterization of some expressed sequences tags (ESTs) in some Cuban tobacco varieties and species. The microarray technology was used with ESTs for the construction of a cDNA library. The most interesting finding in this study was that 265 ESTs had never been reported before in vegetable species and one gene, the Transcriptional Controlled Tumor Protein (TCTP), had never been reported before in N. tabacum, with the studies about this gene being focused on human and animals mostly. The microarray results were confirmed using quantitative RT- PCR. TCTP and pathogenesisrelated protein 1 (PR-1) ESTs were used to design primers for the molecular characterization of some species and Cuban tobacco varieties. In the case of TCTP, six species and four varieties were characterized, and eight varieties for PR1. TCTP was only expressed in two species (Nicotiana glutinosa L. and Nicotiana tomentosiformis Goodsp.) and PR1, after a digestion, exhibited different bands for susceptible and resistant varieties. The detection of these genes in some species and Cuban tobacco varieties is the first step to go further in the molecular characterization of Cuban germoplasm. [ABSTRACT FROM AUTHOR]

Molecular mechanisms underlying inducible cobalt and nickel resistance of a bacterial strain isolated from a Cuban serpentine deposit were investigated. This strain C-1 was assigned to Serratia marcescens by 16S rDNA analysis and DNA/DNA hybridization. Genes involved in metal resistance were identified by transposon mutagenesis followed by selection for cobalt- and nickel-sensitive derivatives. The transposon insertion causing the highest decrease in metal resistance was located in the ncrABC determinant. The predicted NcrA product was a NreB ortholog of the major facilitator protein superfamily and central for cobalt/nickel resistance in S. marcescens strain C-1. NcrA also mediated metal resistance in Escherichia coli and caused decreased accumulation of Co(II) and Ni(II) in this heterologous host. NcrB may be a regulatory protein. NcrC was a protein of the nickel-cobalt transport (NiCoT) protein family and necessary for full metal resistance in E. coli, but only when NcrA was also present. Without NcrA, NcrC caused a slight decrease in metal resistance and mediated increased accumulation of Ni(II) and Co(II). Because the cytoplasmic metal concentration can be assumed to be the result of a flow equilibrium of uptake and efflux processes, this interplay between metal uptake system NcrC and metal efflux system NcrA may contribute to nickel and cobalt resistance in this bacterium.

Heavy metals are required as nutrients for essential functions in microorganisms. However, higher concentrations of these cations are generally toxic and may produce contrasting effects on living organisms. Enterobacter liquefaciens strain C-1, a bacterium isolated from the Moa mine in Cuba, is able to survive in the presence of high concentrations of heavy metals. The proteomes of Enterobacter liquefaciens strain C-1, grown under aerobic conditions in the presence and absence of Co (II) were compared using two-dimensional gel electrophoresis analysis in the isoelectric point range of 4-7 and the mass range of 15-120 kDa. Significant changes in the expression level (> two-fold) were detected for 13 spots: seven and six were up- and down-regulated, respectively. Because the genome of this bacterium is unknown, identification by peptide mass fingerprinting only succeeded in four cases and most of the cross-species identifications were supported by de novo sequencing of tryptic peptides followed by sequence alignment using the MS BLAST program. Twelve different proteins were identified, ten are involved in cellular antioxidant defence probably induced by the presence of Co (II). This is the first step towards understanding the role of proteins participating in the mechanism of resistance to heavy metals in this bacterium.

Pure cultures of Thiobacillus ferrooxidans and mixed cultures of Thiobacillus ferrooxidans and Leptospirillum ferrooxidans isolated from the Matahambre mine (Cuba) were used to fit immunodiffusion and immunoelectron microscopy to the study of iron oxidizing bacteria. The possibilities, advantages and limits of those techniques have been studied from both the identification and the serological characterization points of view. Finally, the efficiency of these methods was tested by applying them to the identification of microorganisms from acidic waters from the mine.

A specific, fast and very sensitive immunoelectron microscopy method was developed to morphologically and serologically distinguish different cultures of iron oxidizers. Bacteria isolated from the acidic waters of "Matahambre" and "Mina Delita" mines (Cuba) were characterized. An antiserum specific to Thiobacillus ferrooxidans did not react with other bacteria also present in the acidic waters of mine drainage. Our results suggest the occurrence of some strains of Thiobacillus ferrooxidans, Thiobacillus thiooxidans and Leptospirillum ferrooxidans in these waters.