Showing papers in "Genetics and Molecular Biology in 2003"
TL;DR: The presence and number of homologues in each gene family in rice and Arabidopsis is discussed in light of the established iron acquisition strategies used by each one of these two plants.
Abstract: Iron is essential for plants However, excess iron is toxic, leading to oxidative stress and decreased productivity Therefore, plants must use finely tuned mechanisms to keep iron homeostasis in each of their organs, tissues, cells and organelles A few of the genes involved in iron homeostasis in plants have been identified recently, and we used some of their protein sequences as queries to look for corresponding genes in the rice (Oryza sativa) genome We have assigned possible functions to thirty-nine new rice genes Together with four previously reported sequences, we analyzed a total of forty-three genes belonging to five known protein families: eighteen YS (Yellow Stripe), two FRO (Fe 3+ -chelate reductase oxidase), thirteen ZIP (Zinc regulated transporter / Iron regulated transporter Protein), eight NRAMP (Natural Resistance - Associated Macrophage Protein), and two Ferritin proteins The possible cellular localization and number of potential transmembrane domains were evaluated, and phylogenetic analysis performed for each gene family Annotation of genomic sequences was performed The presence and number of homologues in each gene family in rice and Arabidopsis is discussed in light of the established iron acquisition strategies used by each one of these two plants
155 citations
TL;DR: No statistically significant alterations were found, as compared to untreated controls, in either the cell cycle or the number of chromosome alterations, after treatments with either plant, in rat cells or in cultured human lymphocytes.
Abstract: The use of medicinal plants by the general population is an old and still widespread practice, which makes studies of their genotoxicity essential. Psidium guajava L. and Achillea millefolium L. are examples of plants commonly used in popular medicine. P. guajava L. is indicated for diarrhea and also as an antiseptic, while A. millefolium L. is indicated as an analgesic, antispasmodic, digestive, diuretic, antiseptic, astringent, emollient, wound healer and hemorrhoid medication. The aim of this study was to determine the effects of the infusions of these two plant species on chromosomes and the cell cycle. Leaves from the plants were used to prepare infusions, in the same manner as teas, but at two different concentrations. Allium cepa L. root-tip cells (P. guajava L. - 2.62 and 26.2 mg/mL, and A. millefolium L. - 3.5 and 35.0 mg/mL) and Wistar rat bone marrow cells (P. guajava L. - 2.62 and 26.2 mg/100g body weight, and A. millefolium L. - 3.5 and 35.0 mg/100g body weight) were used as in vivo plant and animal test systems, respectively. Human peripheral blood lymphocytes (P. guajava L. - 0.262 and 2.62 mg/mL culture medium, and A. millefolium L. - 0.35 and 3.5 mg/mL culture medium) were used as in vitro test system. The P. guajava L. infusion at the higher concentration caused a statistically significant inhibition of cellular division in the onion root-tip cells, not observed in onion root-tip cells treated with A. millefolium L. No statistically significant alterations were found, as compared to untreated controls, in either the cell cycle or the number of chromosome alterations, after treatments with either plant, in rat cells or in cultured human lymphocytes. These results regarding the cytotoxicity and mutagenicity of these plants provide valuable information about the safety of using them as therapeutic agents.
145 citations
TL;DR: A new perspective is opened for the generation of population genetic data and parameters estimates for devising sound collection and conservation procedures for Eugenia dysenterica and a potential of SSR locus transferability developed for Eucalyptus is indicated.
Abstract: The ''cagaita tree'' (Eugenia dysenterica) is a plant found widespread in the Brazilian Cerrado. Its fruit is used for popular consumption and for industrial purposes. This study opens a new perspective for the generation of population genetic data and parameters estimates for devising sound collection and conservation procedures for Eugenia dysenterica. A battery of 356 primer pairs developed for Eucalyptus spp. was tested on the ''cagaita tree''. Only 10 primer pairs were found to be transferable between the two species. Using a polyacrilamide gel, an average of 10.4 alleles per locus was detected, in a sample of 116 individuals from 10 natural ''cagaita tree'' populations. Seven polymorphic loci allowed estimation of genetic parameters, including expected average heterozygosity He = 0,442, among population diversity, RST = 0,268 and gene flow Nm = 0,680. Results indicated a potential of SSR locus transferability developed for Eucalyptus to other species of different genera, such as in the case of the ''cagaita tree''. The high genetic diversity among populations detected with SSR markers indicated that these markers are highly sensitive to detect population structure. Estimated Nm values and the existence of private alleles indicated reduced gene flow and consequently possible damage to the metapopulation structure.
84 citations
TL;DR: Results obtained revealed that the fish in the downstream region nearest the dam have a higher similarity coefficient than those from the other sampling sites that may be related to differences in environmental characteristics in these regions.
Abstract: Many factors have contributed to the destruction of fish habitats. Hydroelectric dams, water pollution and other environmental changes have resulted in the eradication of natural stocks. The aim of this study was to detect the genetic variation in Prochilodus marggravii from three collection sites in the area of influence of the Tres Marias dam (MG) on the Sao Francisco river (Brazil), using the RAPD technique. The results obtained revealed that the fish in the downstream region nearest the dam have a higher similarity coefficient than those from the other sampling sites that may be related to differences in environmental characteristics in these regions. Additionaly, significant differences in the band frequencies were observed from one collection site to another. These both findings suggest the occurrence of a structured population and have important implications for the conservation of the genetic variability of distinct natural P. marggravii stocks.
76 citations
TL;DR: To investigate differences between king weakfish populations, the cytochrome b and 16S rRNA genes were used to characterize M. ancylodon specimens caught throughout its South American range from Venezuela to Argentina and showed nucleotide divergence and genetic structuring patterns that strongly suggest they may be different species.
Abstract: The king weakfish (pescada-go in Portuguese - Macrodon ancylodon (Sciaenidae), a demersal (bottom-feeding) species found in South America Atlantic coastal waters from the Gulf of Paria in Venezuela to Baia Blanca in Argentina, is an economically important species because of its abundance and wide acceptance by consumers. Because of its wide distribution this fish may be subject to geographic isolation and this may have resulted in distinct populations along its coastal range. Considering that this species represents an important economic resource, confirmation of whether M. ancylodon is a single species or there are different genetic stocks spread over its wide distribution would be an important contribution to conservation policies and population management of the king weakfish. To investigate differences between king weakfish populations we used the cytochrome b and 16S rRNA genes to characterize M. ancylodon specimens caught throughout its South American range from Venezuela to Argentina. Our results clearly distinguished two genetically different groups which show nucleotide divergence and genetic structuring patterns that strongly suggest they may be different species, disagreeing with the widely accepted traditional taxonomy that accepts only one species of Macrodon in the western Atlantic.
75 citations
TL;DR: Genetic diversity data showed that, in spite of its nine hydroelectric plants, the Tiete river population was genetically homogeneous, whereas the Paranapanema river populationWas structured, which might be due to the presence of high waterfalls distributed all along its course.
Abstract: Pimelodus maculatus populations from the Tiete and Paranapanema rivers were sampled and had their genetic structure analyzed by using RAPD markers, with the aim of contributing to future conservation studies. The proportion of polymorphic loci was greater than 50% in the populations of both rivers. Genetic diversity data showed that, in spite of its nine hydroelectric plants, the Tiete river population was genetically homogeneous, whereas the Paranapanema river population was structured. This might be due to the presence of high waterfalls distributed all along its course. These data may serve as indicators for future conservation studies on the Tiete and Paranapanema rivers.
73 citations
TL;DR: Inter-simple sequence repeat (ISSR) markers were used to evaluate genetic divergence among eight Coffea species and to identify the parentage of six interspecific hybrids and revealed that ISSR markers could be efficiently used for genetic differentiation of the CoffeA species and as one of the progenitors of those hybrids.
Abstract: Inter-simple sequence repeat (ISSR) markers were used to evaluate genetic divergence among eight Coffea species and to identify the parentage of six interspecific hybrids. A total of 14 primers which contained different simple sequence repeats (SSR) were used as single primers or combined in pairs and tested for PCR amplifications. Two hundred and thirty highly reproducible fragments were amplified, which were then used to estimate the genetic similarity and to cluster the Coffea species and hybrids. High levels of interspecific genetic variation were revealed. The dinucleotide motif (GA)9T combined with other di- tri- and tetra-nucleotides produced a greater number of DNA fragments, mostly polymorphics, suggesting a high frequency of the poly GA microsatellite motifs in the Coffea genomes. The genetic similarity ranged from 0.25 between C. racemosa and C. liberica var. dewevrei to 0.86 between C. arabica var. arabica and Hybrid N. 2. The C. arabica species shared most of its markers with five of the six hybrids suggesting that it is the most likely candidate as one of the progenitors of those hybrids. These results revealed that ISSR markers could be efficiently used for genetic differentiation of the Coffea species and to identify the parentage of Coffea interspecific hybrids.
68 citations
TL;DR: Results suggest that R. catesbeianatadpoles may provide a useful model for monitoring water pollution and increasing concentrations of lambda-cyhalothrin showed an increase in themicronuclei frequency in peripheral blood.
Abstract: Pyrethroid lambda-cyhalothrin genotoxicity was evaluated using the micronucleus test in Rana catesbeianatadpoles.Theeffectsofconcentrationandexposuretimeonthemicronucleifrequencywerestudiedinbloodsmearsobtained from tadpoles exposed to four concentrations (0.02, 0.1, 0.2 and 0.4 µg/L) of the compound for 24, 48, 72and96hand8,15,20and30days.Asapositivecontrol,tadpoleswereexposedtocyclophosphamide(5mg/L).Themicronucleated cell frequency was expressed per 1,000 cells.R. catesbeianatadpoles exposed to increasing concentrations of lambda-cyhalothrin showed an increase in themicronuclei frequency in peripheral blood. Tadpoles exposed to cyclophosphamide (CP) also showed a significantincrease in micronucleated erythrocytes which peaked after 15 days. These results suggest that R. catesbeianatadpoles may provide a useful model for monitoring water pollution. Key words: genotoxicity, micronucleus test, lambda-cyhalothrin, tadpoles . Received: June 21, 2000; accepted: December 4, 2002.
62 citations
59 citations
TL;DR: The previously identified interaction between the IGF-1 genotype and genetic group strengthens the hypothesis of a linked QTL rather than an IGF- 1 effect on growth traits in the Canchim cattle.
Abstract: The objective of this work was to identify QTLs for liveweight in a candidate region of bovine chromosome 5. Half-sib families from two lines, one traditional and the other new, of Canchim beef cattle (5/8 Charolais + 3/8 Zebu) were genotyped for four microsatellite markers, including the microsatellite in the IGF-1 (insulin-like growth factor-1) promoter region. Significant differences in allele distribution between the two lines were found for three markers. Interval mapping analyses in this region indicated the presence of a QTL controlling birth weight (p < 0.05) and of a QTL influencing breeding value for yearling weight (p < 0.01) in the newer line of the breed. The previously identified interaction between the IGF-1 genotype and genetic group strengthens the hypothesis of a linked QTL rather than an IGF-1 effect on growth traits in the Canchim cattle.
57 citations
TL;DR: Observations of the time of larva and adult onset suggested that developmental time was also delayed in treatments with both substances, and esterases (enzymes involved in the detoxification of xenobiotics) were analyzed in polyacrylamide gels of treated 4th instar larvae (L4).
Abstract: Caffeine and used coffee grounds completely blocked the development of Aedes aegypti in the early stages, in treatments with the concentrations 1.0 mg/mL and 50 mg/mL, respectively. More advanced stages and even adults were obtained in lower concentrations of both substances, enabling observations to be made of mortality rate, longevity and esterase patterns. The experiments involved treatments using either eggs or 3rd instar larvae (L3), with or without the addition of fish food. Mortality rates prior to the adult stage and adult longevity were significantly different in the comparisons among treatments, in every kind of experiment, but in those using L3 larvae, their percentages were smaller. Observations of the time of larva and adult onset suggested that developmental time was also delayed in treatments with both substances. The addition of fish food increased significantly the number of adults produced in caffeine 0.2 and in the control, but in used coffee grounds, the opposite effect occurred. Longevity was apparently not affected by the addition of food, except again in coffee grounds, in which it decreased. In an attempt to detect a mechanism involved in the action of caffeine and coffee grounds, esterases (enzymes involved in the detoxification of xenobiotics) were analyzed in polyacrylamide gels of treated 4th instar larvae (L4). In treatments with both substances, the expression of some carboxylesterases was affected, suggesting that they may be involved in the observed impairment.
TL;DR: The distribution limit of African bee colonies, i.e., those populations with only the African mtDNA haplotype and with a high proportion of African genes as shown by allozyme analysis, is located in northern Uruguay, with a hybridization zone located farther south in Uruguay.
Abstract: Apis mellifera scutellata was introduced to Brazil in 1956 and Africanized honeybee populations have now spread from Argentina to the southwestern United States. Temperate climatic restrictions seem to be a natural limit to Africanized honeybee expansion around parallels 35° to 40° SL. We used allozyme loci (Mdh-1 and Hk-1) and mtDNA haplotypes to characterize honeybee populations in southern Brazil and Uruguay and define a possible transition area between Africanized and European bees. Samples of 194 bee colonies were collected from ten localities between 30°-35° SL and 52°-59° WL. The mtDNA restriction patterns of these colonies were obtained through digestion of the mitochondrial genome by Eco RI, or by digestion by Bgl II and Xba I of the cytochrome B locus and the COI-COII intergenic region, respectively. The distribution limit of African bee colonies, i.e., those populations with only the African mtDNA haplotype and with a high proportion of African genes as shown by allozyme analysis, is located in northern Uruguay, with a hybridization zone located farther south in Uruguay. A gradual cline from north to south was observed, confirmed by mtDNA, racial admixture, and genetic distance analyses. No evidence of either gametic disequilibrium between nuclear markers or cytonuclear disequilibrium among the nuclear and mtDNA genotypes was detected, suggesting that the hybridization process has been completed.
TL;DR: Aberdeen Angus beef cattle from the Brazilian herd were studied genetically using restriction fragment length polymorphism (RFLP) of the k-casein - HinfI, b-lactoglobulin - HaeIII and growth hormone AluI genes, as well as four microsatellites.
Abstract: Aberdeen Angus beef cattle from the Brazilian herd were studied genetically using restriction fragment length polymorphism (RFLP) of the k-casein - HinfI (CSN3 - HinfI), b-lactoglobulin - HaeIII (LGB - HaeIII) and growth hormone AluI (GH- AluI) genes, as well as four microsatellites (TEXAN15, CSFM50, BM1224 and BM7160). The RFLP genotypes were determined using the polymerase chain reaction (PCR) followed by digestion with restriction endonucleases and electrophoresis in agarose gels. With the exception of the microsatellite BM7160, which was analyzed in an automatic sequencer, the PCR products were genotyped by silver staining. The allele and genotype frequencies, heterozygosities and gene diversity were estimated. The values for these parameters of variability were comparable to other cattle breeds. The genetic relationship of the Aberdeen Angus to other breeds (Caracu, Canchim, Charolais, Guzerath, Gyr, Nelore, Santa Gertrudis and Simmental) was investigated using Nei's genetic distance. Cluster analysis placed the Aberdeen Angus in an isolated group in the Bos taurus breeds branch. This fact is in agreement with the geographic origin of this breed.
TL;DR: D-loop mitochondrial DNA analyses were applied in six wild populations of L. elongatus, and it was possible to detect high levels of genetic variability within each population and the occurrence of exclusive population haplotypes, which suggests a partial genetic differentiation among them.
Abstract: Leporinus elongatus, a fish species widely distributed throughout the Parana River basin in South America, is an important fishery resource and a valuable species in aquaculture programs. Despite its great economic importance, several wild populations have been suffering a drastic reduction. The comprehension of its population structure represents an important step for the conservation of these organisms in natural environments, and also for the selection of wild stocks to be used in hatchery programs. In order to understand the genetic-population structure of L. elongatus, D-loop mitochondrial DNA analyses were applied in six wild populations of the species. The results were used to estimate the levels of within and among population genetic variability. Although the D-loop variations could not be correlated to the geographic distribution of these organisms, it was possible to detect high levels of genetic variability within each population and the occurrence of exclusive population haplotypes, which suggests a partial genetic differentiation among them. The obtained data can be useful in selecting fish stocks that preserve a better genetic diversity of L. elongatus for use in conservation and/or hatchery programs.
TL;DR: Estimation of general and specific combining ability effects in a diallel analysis of cross-pollinating populations, including the selfed parents, is presented in this work, which was used to select popcorn populations for intra- and inter-population breeding programs and for hybrid production.
Abstract: Estimation of general and specific combining ability effects in a diallel analysis of cross-pollinating populations, including the selfed parents, is presented in this work. The restrictions considered satisfy the parametric values of the GCA and SCA effects. The method is extended to self-pollinating populations (suitable for other species, without the selfed parents). The analysis of changes in population means due to inbreeding (sensitivity to inbreeding) also permits to assess the predominant direction of dominance deviations and the relative genetic variability in each parent population. The methodology was used to select popcorn populations for intra- and inter-population breeding programs and for hybrid production, developed at the Federal University of Vicosa, MG, Brazil. Two yellow pearl grain popcorn populations were selected.
TL;DR: The mitochondrial 16S rRNA mitochondrial results show Bradypodidae as a monophyletic and robustly supported clade in all the analysis and indicates that trichotomy best represents the relationship between the families Mylodontidae, Bradypdidae and Megalonychidae.
Abstract: We sequenced part of the 16S rRNA mitochondrial gene in 17 extant taxa of Pilosa (sloths and anteaters) and used these sequences along with GenBank sequences of both extant and extinct sloths to perform phylogenetic analysis based on parsimony, maximum-likelihood and Bayesian methods. By increasing the taxa density for anteaters and sloths we were able to clarify some points of the Pilosa phylogenetic tree. Our mitochondrial 16S results show Bradypodidae as a monophyletic and robustly supported clade in all the analysis. However, the Pleistocene fossil Mylodon darwinii does not group significantly to either Bradypodidae or Megalonychidae which indicates that trichotomy best represents the relationship between the families Mylodontidae, Bradypodidae and Megalonychidae. Divergence times also allowed us to discuss the taxonomic status of Cyclopes and the three species of three-toed sloths, Bradypus tridactylus, Bradypus variegatus and Bradypus torquatus. In the Bradypodidae the split between Bradypus torquatus and the proto-Bradypus tridactylus / B. variegatus was estimated as about 7.7 million years ago (MYA), while in the Myrmecophagidae the first offshoot was Cyclopes at about 31.8 MYA followed by the split between Myrmecophaga and Tamandua at 12.9 MYA. We estimate the split between sloths and anteaters to have occurred at about 37 MYA.
TL;DR: The terminal location of the single 45S rDNA site in the 2n = 4 race suggested that disploid reduction in Rhynchospora was followed by elimination or reorganization events, keeping the terminal distribution of these sites, as in an others species of the genus.
Abstract: Rhynchospora tenuis Link (Cyperaceae) is a weed widely distributed in Brazil that presents a small number of holocentric chromosomes (2n = 4) with some autopolyploid populations (2n = 8). The haploid number n = 2 is considered as a derivative of the base number x = 5. 45S rDNA probes and telomeric DNA were hybridized in both chromosome races of R. tenuis, looking for indications of chromosome fusions. The results showed that hybridization sites of the telomeric probe were restricted to end chromosome regions whereas rDNA sites were terminally located. The chromosome race with n = 4 exhibited a doubled number of sites, with similar size and location to the hybridized sequences, confirming its autopolyploid origin. Furthermore, the terminal location of the single 45S rDNA site in the 2n = 4 race suggested that disploid reduction in Rhynchospora, from n = 5 to n = 2, was followed by elimination or reorganization events, keeping the terminal distribution of these sites, as in an others species of the genus.
TL;DR: Thinopyrum ponticum belongs to the Triticeae tribe, and is currently used as a source of pathogen resistance genes in wheat breeding, and the number and position of 45S and 5S rDNA sites, as well as the distribution of the repetitive DNA sequences pAs1 and pSc119.2, were identified by fluorescent in situ hybridization.
Abstract: Thinopyrum ponticum (2n = 10x = 70, JJJJsJs) belongs to the Triticeae tribe, and is currently used as a source of pathogen resistance genes in wheat breeding. In order to characterize its chromosomes, the number and position of 45S and 5S rDNA sites, as well as the distribution of the repetitive DNA sequences pAs1 and pSc119.2, were identified by fluorescent in situ hybridization. The number of nucleoli and NORs was also recorded after silver nitrate staining. Seventeen 45S and twenty 5S rDNA sites were observed on the short arms of 17 chromosomes, the 45S rDNA was always located terminally. On three other chromosomes, only the 5S rDNA site was observed. Silver staining revealed a high number of Ag-NORs (14 to 17) on metaphase chromosomes, whereas on interphase nuclei there was a large variation in number of nucleoli (one to 15), most of them (82.8%) ranging between four and nine. The pAs1 probe hybridized to the terminal region of both arms of all 70 chromosomes. In addition, a disperse labeling was observed throughout the chromosomes, except in centromeric and most pericentromeric regions. When the pSc119.2 sequence was used as a probe, terminal labeling was observed on the short arms of 17 chromosomes and on the long arms of five others. The relative position of 45S and 5S rDNA sites, together with the hybridization pattern of pAs1 and pSc119.2 probes, should allow whole chromosomes or chromosome segments of Th. ponticum to be identified in inbred lines of wheat x Th. ponticum.
TL;DR: The promoter region and the beginning of the coding region of the hsp70 stress gene were analysed in broiler chickens of a commercial breed, a breed selected for weight gain and a non-selected breed, indicating that the regulation pattern of this gene must be the same in all birds at the promoter region.
Abstract: The promoter region and the beginning of the coding region of the hsp70 stress gene were analysed in broiler chickens of a commercial breed (Hubbard-Pettersen), a breed selected for weight gain (PP1) and a non-selected breed (naked-neck Label Rouge). The naked neck gene (Naked neck, Na), which reduces feathering in birds and is thus related to heat resistance, was present in both PP1 and Label Rouge breeds. Genomic DNA was restricted with PstI and Southern blotting analysis of the samples revealed the absence of polymorphic sites for that enzyme in the promoter region and beginning of the coding region of the hsp70 gene of studied birds. PCR-SSCP analysis of these regions, however, indicated the presence of polymorphisms in the beginning of the coding region and the sequencing of the PCR products confirmed and identified two polymorphic sites in this region: a transition A ® G in position +258 and a transversion C ® G in position +276. Both mutations were considered to be silent, since they did not modify the aminoacid sequence of the protein Hsp70. The promoter region of the hsp70 gene was identical in all studied birds, indicating that the regulation pattern of this gene must be the same in all birds at the promoter region. Three different alleles (hsp70-1, hsp70-2 and hsp70-3) were identified for the hsp70 gene from the observed mutations. The allele hsp70-3 was detected in only two breeds, Hubbard-Pettersen and PP1, but at a low frequency (0,016 and 0,006, respectively).
TL;DR: The isolation of (GA)n microsatellites using a highly microsatellite-enriched library using biotin-conjugated oligonucleotids and non-radioactive colony hybridization was carried out and the first MADS-box locus described to date in common bean was identified.
Abstract: The isolation of (GA)n microsatellites using a highly microsatellite-enriched library is described for the first time in common bean (Phaseolus vulgaris L.). A relatively simple and effective method to isolate DNA repeats from microsatellite-enriched libraries based on hybridization-capture of repeat regions using biotin-conjugated oligonucleotids and non-radioactive colony hybridization was carried out. PCR products from 200 to 800 bp were obtained and cloned. Of the 60 clones sequenced, 21 yielded (GA)n microsatellites with n values equal or higher than six. These (GA)n microsatellite-containing loci could be useful for further genetic mapping studies. A (GA)n microsatellite linked to a putative MADS-box gene was identified. This sequence, which represents the first MADS-box locus described to date in common bean, showed a very high similarity with other known MADS-box sequences and was grouped within the AGL2 subfamily cluster of the Arabidopsis MADS-box genes. The vicinity of microsatellites to some genes is also discussed.
TL;DR: The RAPD technique associated with restriction digestion was proved to be a useful tool for genetic characterization of C. arabica genotypes making an important contribution to the application of molecular markers to coffee breeding.
Abstract: Knowledge of the genetic variability among genotypes is important for the transfer of useful genes and to maximize the use of available germplasm resources. This study was carried out to assess the genetic variability of 14 elite Coffea arabica cultivars using random amplified polymorphic DNA (RAPD) associated with a prior digestion of genomic DNA with restriction endonucleases. The accessions were obtained from the Coffea collection maintained at the Instituto Agronomico do Parana (IAPAR), located in Londrina, Parana, Brazil. Twenty-four informative RAPD primers, used in association with restriction enzymes, yielded 330 reproducible and scorable DNA bands, of which 224 (68%) were polymorphic. The amplified products were used to estimate the genetic variability using Dice's similarity coefficient. The data matrix was converted to a dendrogram and a three-dimensional plot using principal coordinate analysis. The accessions studied were separated into clusters in a manner that was consistent with the known pedigree. The associations obtained in the dendrogram and in the principal coordinate analysis plot suggest the probable origin of the Kattimor cultivar. The RAPD technique associated with restriction digestion was proved to be a useful tool for genetic characterization of C. arabica genotypes making an important contribution to the application of molecular markers to coffee breeding.
TL;DR: The results suggested that for this particular population of T. grandiflorum, the sampling strategy for genetic conservation and breeding should adopt specific models for families derived from correlated outcrossing (full-sibs) and not the ones usually adopted in classic outcrossed species breeding programs (half-sIBs).
Abstract: The aim of this research was to study the mating system of a natural population of Theobroma grandiflorum (cupuassu) from Nova Ipixuna, Para state, using microsatellite markers. Eight polymorphic microsatellite loci were analyzed in eight families, each represented by 10 six-month old seedlings derived from open-pollinated pods. The estimation for the multilocus outcrossing rate (m = 1.0) and individual outcrossing rate ( = 1.0) for this population suggests that T. grandiflorum may be a perfect outbreeding (allogamous) species. Likewise, for the studied population the estimate for single locus outcrossing rate (S) was elevated (0.946), but lower than m, confirming the likely outcrossing character of the species and suggesting the occurrence of 5.4% biparental inbreeding rate (m - S). The estimation of genetic divergence (st) between allelic frequencies in ovules and pollen revealed a deviation from random mating in 75% of the evaluated loci. Likewise, the estimate of correlation of paternity (P = 0.930) and the mean coefficient of co-ancestrality within families (XY = 0.501) indicated that the outcrossings were predominantly correlated, and the offspring were full-sibs. These results suggested that for this particular population of T. grandiflorum, the sampling strategy for genetic conservation and breeding should adopt specific models for families derived from correlated outcrossing (full-sibs) and not the ones usually adopted in classic outcrossing species breeding programs (half-sibs).
TL;DR: This study identified RAPD and SSR markers associated with a resistant allele for angular leaf spot from the line 'ESAL 550', derived from the Andean 'Jalo EEP 558' cultivar, to assist selection of resistant genotypes.
Abstract: The objective of this study was to identify RAPD and SSR markers associated with a resistant allele for angular leaf spot (Phaeoisariopsis griseola) from the line 'ESAL 550', derived from the Andean 'Jalo EEP 558' cultivar, to assist selection of resistant genotypes. The resistant line 'ESAL 550' and the susceptible cultivar 'Carioca MG' were crossed to generate F1 and F2 populations. One hundred and twenty F2:3 families were evaluated. The DNA of the 12 most resistant families was bulked and the same was done with the DNA of the 10 most susceptible, generating two contrasting bulks. One RAPD and one SSR marker was found to be linked in coupling phase to the resistant allele. The SSR marker was amplified by the primer PV-atct001282C, and its distance from the resistant allele was 7.6 cM. This is the most useful marker for indirect selection of resistant plants in segregating populations. The RAPD marker was amplified by the primer OPP07857C linked in coupling phase to the resistant allele, and distant 24.4 cM. Therefore, this RAPD marker is not so useful in assisting selection because it is too far from the resistant allele.
TL;DR: The stability analysis identified GT 1 and IAN 873 as the most stable clones for girth growth and rubber yield respectively since their regression coefficients were almost the unity (b = 1) and they had one of the lowest deviations from regressions (S2di).
Abstract: The best-yielding, best vigour and most stable Hevea clones are identified by growing clones in different environments. However, research on the stability in Hevea brasiliensis (Willd. Adr. ex Juss.) Muell.-Arg. is scarce. The objectives of this work were to assess genotype-environment interaction and determine stable genotypes. Stability analysis were performed on results for girth growth and rubber yield of seven clones from five comparative trials conducted over 10 years (girth growth) and four years (rubber yield) in Sao Paulo State, Brazil. Stability was estimated using the Eberhart and Russell (1966) method. Year by location and location variability were the dominant sources of interactions. The stability analysis identified GT 1 and IAN 873 as the most stable clones for girth growth and rubber yield respectively since their regression coefficients were almost the unity (b = 1) and they had one of the lowest deviations from regressions (S2di). Their coefficient of determination (R2) was as high as 89.5% and 89.8% confirming their stability. In contrast, clones such as PB 235, PR 261, and RRIM 701 for girth growth and clones such as GT 1 for rubber yield with regression coefficients greater than one were regarded as sensitive to environment changes.
TL;DR: Plant esterases may be used as bioindicators to detect the presence and toxicity of residues of topically applied insecticides in agriculture and may be valuable for monitoring pollutants in the environment.
Abstract: Polyacrylamide gel electrophoresis system (PAGE) and inhibition tests for biochemical characterization of a- and b-esterases were used to obtain a functional classification of esterases fromAspidosperma polyneuron. The characterization of a- and b-esterases from young leaves of A. polyneuron by the PAGE system showed fourteen esterase isozymes. The differential staining pattern showed that Est-2 isozyme hydrolyzes b-naphthyl acetate; Est-6, Est-7 and Est-8 isozymes hydrolyze a-naphthyl acetate, and Est-1, Est-3, Est-4, Est-5, Est-9, Est-10, Est-11, Est-12, Est-13, and Est-14 isozymes hydrolyze both a- and b-naphthyl acetate. Inhibition pattern of a- and b-esterases showed that Folidol is a more potent inhibitor that Malathion, while Thiamethoxan (an insecticide with organophosphorus-like action) acts as an Est-4 and Est-6 inhibitor and induces the appearance of Est-5 and Est-7 isozymes as more intensely stained bands. Inhibition tests showed that OPC insecticides inhibit or activate plant esterases. Thus, plant esterases may be used as bioindicators to detect the presence and toxicity of residues of topically applied insecticides in agriculture and may be valuable for monitoring pollutants in the environment.
TL;DR: The RAPD technique used to determine the genetic variability within and among C. arabicaL populations providing significant information for coffee breeding was useful, and a distinct level of genetic variability was revealed for each of the coffee progenies and varieties studied.
Abstract: TheRAPDtechniqueassociatedwithrestrictiondigestionofgenomicDNAwasusedtoassessthegeneticvariabilitywithin and among nine populations of Coffea arabica, including six progenies belonging to the Sarchimorgermplasm, the progeny PR 77054-40-10 (Catuai Vermelho IAC 81 x Icatu), and two commercial cultivars (IAPAR59andCatuaiVermelhoIAC-81).Thesepopulationswereevaluatedusinganalysisofmolecularvariance(AMOVA),genetic similarity among progenies, and percentage of polymorphic loci. A total of 99 RAPD markers were evaluatedof which 67 (67.67%) were polymorphic. AMOVA showed that 38.5% and 61.5% of the genetic variation wasdistributed among and within populations, respectively. The fixation index (F ST ) of the genotypes was 0.385. Themean genetic variability estimated within populations ranged from 15.58 (IAPAR 59) to 8.27 (Catuai Vermelho IAC81). A distinct level of genetic variability was revealed for each of the coffee progenies and varieties studied. Themethodology used in this investigation was useful to determine the genetic variability within and among C. arabicaL.populations providing significant information for coffee breeding.
TL;DR: The amplified fragment length polymorphism (AFLP) assay is an efficient method for the identification of molecularmarkers, useful in the improvement of numerous crop species, and would permit rapid selection of water-stress tolerant genotypes in breeding programs.
Abstract: The amplified fragment length polymorphism (AFLP) assay is an efficient method for the identification of molecularmarkers, useful in the improvement of numerous crop species. Bulked Segregant Analysis (BSA) was used toidentify AFLP markers associated with water-stress tolerance in barley, as this would permit rapid selection ofwater-stress tolerant genotypes in breeding programs. AFLP markers linked to water-stress tolerance was identifiedin two DNA pools (tolerant and sensitive), which were established using selected F 2 individuals resulting from acrossbetween water-stress-tolerant and sensitive barley parental genotypes, based on their paraquat (PQ) tolerance, leafsize, and relative water content (RWC). All these three traits were previously shown to be associated withwater-stress tolerance in segregating F 2 progeny of the barley cross used in a previous study. AFLP analysis wasthen performed on these DNA pools, using 40 primer pairs to detect AFLP fragments that are present/absent,respectively, in the two pools and their parental lines. One separate AFLP fragment, which was present in thetolerant parent and in the tolerant bulk, but absent in the sensitive parent and in the sensitive bulk, was identified.Polymorphism of the AFLP marker was tested among tolerant and sensitive F
TL;DR: Heterochromatin was localized in all chromosome pericentromeric regions but some blocks could be visualized on some large chromosomes arms, suggesting that DA-CMA3-positive bands of P. peckolti correspond to nucleolar organizer regions, as previously confirmed for another Partamona species by FISH.
Abstract: The stingless bees of the Partamona genus have been studied taxonomically, ecologically and behaviourally, but cytogenetic studies are still rare. The objective of this study was to obtain cytogenetic data to contribute to Partamona peckolti species characterization. Heterochromatin was localized in all chromosome pericentromeric regions but some blocks could be visualized on some large chromosomes arms. A large heterozygous DA-CMA3-positive band was observed on one large chromosome arm, but was completely absent when C banding was applied before fluorochrome staining, with only one small positive band being visualized. Sequential DA-CMA3-NOR staining of interphase nuclei provided coincident positive responses. This suggests that DA-CMA3-positive bands of P. peckolti correspond to nucleolar organizer regions, as previously confirmed for another Partamona species by FISH.
TL;DR: Eletrophoresis of total blood serum in Bufo ictericus, Bufe paracnemis and the intermediate specimens revealed a remarkable difference in the patterns of the protein bands whose molecular weight corresponded to that of albumin.
Abstract: Specimens of Bufo ictericus, Bufo paracnemis and a third type, considered an intermediate subgroup between these species, were cytogenetically studied by conventional Giemsa staining, C-banding and staining of the nucleolus organizer region (NOR). The nuclear DNA content and seroproteins were also analyzed to characterize these species, and verify the possibility of hybridization between them. Karyotypes and cytogenetic markers were essentially equal on the basis of the methods used. The DNA nuclear content found was 6.25 ± 0.30 pg/DNA in Bufo ictericus; 7.57 ± 0.40 pg/DNA in Bufo paracnemis and 7.04 ± 0.29 pg/DNA in the intermediate subgroup. Eletrophoresis of total blood serum in Bufo ictericus, Bufo paracnemis and the intermediate specimens revealed a remarkable difference in the patterns of the protein bands whose molecular weight corresponded to that of albumin. While the parental species presented two different bands, the intermediate form presented 4. However, only three of these bands were seen in each specimen. The results obtained pointed to a high probability for natural hybridization between Bufo ictericus and Bufo paracnemis in the site and specimens studied.
TL;DR: Despite the high level of selection applied to two tropical maize populations and their synthetics, the total gene diversity found in the synthetics allows them to be used in a new RRS cycle.
Abstract: A modified reciprocal recurrent selection (RRS) method, which employed one cycle of high-intensity selection, was applied to two tropical maize (Zea mays L.) populations, BR-105 and BR-106, originating the improved synthetics IG-3 and IG-4, respectively. In the present study the effects of this kind of selection on the genetic structure of these populations and their synthetics were investigated at 30 microsatellite (SSR) loci. A total of 125 alleles were revealed. A reduction in the number of alleles was observed after selection, as well as changes in allele frequencies. In nearly 13% (BR-105) and 7% (BR-106) of the loci evaluated, the changes in allele frequencies were not explained, exclusively due to the effects of genetic drift. The effective population sizes estimated for the synthetics using 30 SSR loci were similar to those theoretically expected after selection. The genetic differentiation (GST) between the synthetics increased to 77% compared with the original populations. The estimated RST values, a genetic differentiation measure proper for microsatellite data, were similar to those obtained for GST. Despite the high level of selection applied, the total gene diversity found in the synthetics allows them to be used in a new RRS cycle.