The Paradox of Self-Fertile Varieties in the Context of Self-Incompatible Genotypes in Olive.

Olive, representing one of the most important fruit crops of the Mediterranean area, is characterized by a general low fruit yield, due to numerous constraints, including alternate bearing, low flower viability, male-sterility, inter-incompatibility, and self-incompatibility (SI). Early efforts to clarify the genetic control of SI in olive gave conflicting results, and only recently, the genetic control of SI has been disclosed, revealing that olive possesses an unconventional homomorphic sporophytic diallelic system of SI, dissimilar from other described plants. This system, characterized by the presence of two SI groups, prevents self-fertilization and regulates inter-compatibility between cultivars, such that cultivars bearing the same incompatibility group are incompatible. Despite the presence of a functional SI, some varieties, in particular conditions, are able to set seeds following self-fertilization, a mechanism known as pseudo-self-compatibility (PSC), as widely reported in previous literature. Here, we summarize the results of previous works on SI in olive, particularly focusing on the occurrence of self-fertility, and offer a new perspective in view of the recent elucidation of the genetic architecture of the SI system in olive. Recent advances in research aimed at unraveling the molecular bases of SI and its breakdown in olive are also presented. The clarification of these mechanisms may have a huge impact on orchard management and will provide fundamental information for the future of olive breeding programs.

Molecular epidemiology of Shiga toxin-producing O113:H21 isolates from cattle and meat.

The serotype O113:H21 is considered one of the relevant non-O157 STEC serotypes associated with severe human infections. Due to the increased detection of O113 strains and their relationship with clinical cases, which emphasizes the importance of this serogroup as an emerging pathogen, our aim was to determine the characteristics of STEC O113:H21 strains circulating in bovine cattle and retail meat from Argentina. For this purpose, we determined the presence and combinations of various virulence genes (and their variants) related to adhesion and toxicity in a collection of 34 isolates. Their genetic relatedness using multiple-locus variable-number tandem repeat analysis (MLVA) was also studied. Subtyping of stx genes indicated that O113:H21 strains circulating in Argentina mainly present stx2a alone or together with stx2c or, less frequent, with stx2d , all of which are subtypes associated with human disease. We found plasmid markers, such as saa, ehxA and subA, in a higher proportion than previous studies, and five variants of saa, two of which were novel ones. In relation to MLVA subtyping, we detected a limited diversity among the isolates considering that several loci were not discriminative and, that in some farms, the same clone seemed to remain circulating throughout the year. The O113:H21 strains studied harbour several toxin and adhesion genes (saa, espP, fimCD, ehaA, iha, hcpA, elfA, lpfO113, ecpA, subA, cdt-V) and Stx subtypes associated with human disease. Results also highlighted that subtyping of stx and saa is useful to discriminate O113:H21 strains that share virulence genes. In conclusion, this study shows that a number of O113:H21 strains that occur in foods and bovines could be pathogenic for humans. This situation calls for further attention in the prevention and control of foodborne disease caused by these strains.

Cryptic introgression of Dasypyrum villosum parental DNA in wheat lines derived from intergeneric hybridization.

Cytogenetic and DNA molecular analyses have been carried out in 3 wheat introgression lines (ILs; CS×V58, CS×V59, and CS×V60) derived from Triticum aestivum cv. 'Chinese Spring' (CS) × Dasypyrum villosum(Dv) intergeneric hybridization. All lines, which showed several phenotypic differences compared to CS, had the same chromosome number (2n = 42) and structure as CS, and neither chromosomes nor chromatin from Dv were apparently added to their complement. However, Feulgen/DNA cytophotometry showed that there was more nuclear DNA in the lines than in the parental wheat (by 1.85%, 2.76%, and 1.26% in CS×V58, CS×V59, and CS×V60, respectively). Molecular investigation indicated the presence of Dv DNA in the ILs. AFLP analysis of genomic DNA from the ILs, CS, and Dv detected a total of 120 polymorphic bands, of which 7 (5.8%) were present in some or all the ILs and Dv but were absent in CS. PCR amplification, sequence analysis of amplicons, and Southern blot hybridization confirmed the presence of Dv-specific sequences in each of the ILs. These results indicate cryptic introgression of Dv DNA sequences into the genome of the ILs. Some implications of this finding are discussed.

Intraspecific genotypic diversity in plants.

Variations in the nuclear DNA, mainly as a result of quantitative modulations of DNA repeats belonging to different sequence families of satellite DNA and to the activity of transposable elements, have been assessed within several angiosperm species. These variations alter the amount and organization of the DNA and therefore the genotype, rather than the genome proper. They take place on an evolutionary time scale as the result of selection processes after the occurrence of uncontrolled events in the genome or may be due to direct responses of plant genomes to environmental stimuli that occur under plant-level control within a short developmental period of a single generation. These DNA changes are correlated to changes in the developmental dynamics and phenotypic characteristics of the plants, and the capability to carry out genotypic variation is an evolutionary trait that allows plant species to adapt to different environmental conditions, as well as to the variability of conditions in a given environment. The link between developmental and environmental stimuli and repetitive DNA that elicits the intraspecific diversity of plant genotypes may provide models of evolutionary change that extend beyond the conventional view of evolution by allelic substitution and take into account epigenetic effects of the genome structure.

Adolescent smokers are at greater risk for current asthma and rhinitis.

BACKGROUND: The association of tobacco smoke with the prevalence of asthma and rhinitis has not been well-characterized in adolescents. METHODS: As part of the International Study of Asthma and Allergies in Childhood (ISAAC), we conducted a cross-sectional survey of 3000 adolescents aged 13-14 years in northern Argentina. Data included questions about asthma and rhinitis symptoms and about parental and personal smoking. Logistic regression and Pearson chi(2) statistics were used to estimate these associations. RESULTS: Over 13% of respondents described themselves as current smokers, and half indicated that at least one parent smoked at home. Active smoking was associated with both asthma (OR 1.83, 95%CI 1.42-2.35) and rhinitis (OR 1.61, 95%CI 1.33-1.92) in unadjusted analysis. These associations persisted after adjusting for parental smoking status, mother's educational level and sex. Boys were significantly less likely than girls to report current asthma or rhinitis. CONCLUSIONS: Active and passive smoking are both risk factors for asthma and rhinitis in adolescents. Assuming that some children with asthma never started smoking due to symptoms, then the true risk could be higher than reported here. These results reinforce the need to develop better strategies for primary and secondary prevention of tobacco exposure in children.

Apomixis and sexuality in Paspalum simplex: characterization of the mode of reproduction in segregating progenies by different methods.

Segregating progenies of crosses between sexual and apomictic genotypes of Paspalum simplex were analysed for the formation of meiotic versus aposporous embryo sacs, zygotic versus parthenogenetic embryos, and autonomous versus pseudogamous endosperms by using cytoembryological and flow cytometric analyses. Reduced and unreduced 8-nucleated embryo sacs were the final product of female gametophyte development in sexual and aposporous genotypes, respectively. An incomplete penetrance of parthenogenesis was detected in aposporous genotypes. The relative DNA content of endosperm nuclei revealed the normal 2:1 maternal to paternal ratio in sexuals and a 4:1 ratio in apomicts, indicating insensitivity of the apomictic genotypes to endosperm imprinting. Apospory, parthenogenesis and pseudogamy are located on a relatively large linkage group and are inherited together with previously developed molecular markers as a single genetic unit in segregating progenies.

Acute encephalopathy and intractable seizures in a 10-year-old boy.

We report a 10-year-old child with Robinow's syndrome who had a 2-week history of headaches and dizziness. On the day of admission, he developed a focal onset seizure with rapid secondary generalization. The seizures were intractable despite adequate doses of benzodiazepine, phenytoin, and phenobarbital, requiring a pentobarbital drip. Continuous electroencephalogram (EEG) monitoring showed persistence of the epileptiform discharges for 13 days. Cerebrospinal fluid and brain biopsy studies were unrevealing. Mycoplasma pneumonia titers showed elevation of both immunoglobulins G and M that doubled during the tenth hospital day. High-dose methylprednisolone was begun, and within 12 hours of initiation the patient sat up and began to follow commands appropriately. The overall EEG background markedly improved. Central nervous system Mycoplasma pneumoniae infection should be suspected in patients with an encephalopathy of unclear etiology.

Pico flujo espiratorio: valores normales de la ciudad de Salta y correlación con tablas de Polgar / The peak expiratory flow: normal values of the Salta city and correlation with Polgar's table

El Pico Flujo Expiratorio (PFE) es útil en el seguimiento de los pacientes con asma moderada y severa, teniendo como parámetros de valores normales las tablas de Polgar. En la práctica diaria, nos encontramos con valores que de acuerdo a esta tabla pareciera no corresponder a la clínica que presenta el paciente. Hemos realizado la medición de PFE en 514 niños asintomáticos respiratorios con dos medidores distintos (Vitalograph - Assess) a fin de evaluar si hubiere diferencias entre estos aparatos y con las tablas de Polgar. Los resultados obtenidos muestran una correlación positiva, que nos permite sugerir que aunque las mediciones realizadas parecieran no coincidir con el cuadro clínico, los valores de las tablas de Polgar son útiles como guía y que la lectura de los dos medidores similares

Pico flujo espiratorio: valores normales de la ciudad de Salta y correlación con tablas de Polgar / The peak expiratory flow: normal values of the Salta city and correlation with Polgars table

El Pico Flujo Expiratorio (PFE) es útil en el seguimiento de los pacientes con asma moderada y severa, teniendo como parámetros de valores normales las tablas de Polgar. En la práctica diaria, nos encontramos con valores que de acuerdo a esta tabla pareciera no corresponder a la clínica que presenta el paciente. Hemos realizado la medición de PFE en 514 niños asintomáticos respiratorios con dos medidores distintos (Vitalograph - Assess) a fin de evaluar si hubiere diferencias entre estos aparatos y con las tablas de Polgar. Los resultados obtenidos muestran una correlación positiva, que nos permite sugerir que aunque las mediciones realizadas parecieran no coincidir con el cuadro clínico, los valores de las tablas de Polgar son útiles como guía y que la lectura de los dos medidores similares (AU)

Segregation analysis of RFLP markers reveals a tetrasomic inheritance in apomictic Paspalum simplex.

Apomictic tetraploid Paspalum simplex was crossed with colchicine-doubled diploid sexual plants belonging to the same species. Homologous genomic probes were selected from a partial PstI genomic library for their capacity to detect alleles specific to the apomictic parent, and their segregation was analyzed in the F1 progeny. High levels of polymorphism between apomictic and sexual genotypes were recorded. The heterozygosity was high in both tetraploid and diploid genotypes but the differences between them were not as great as expected. In the sexual parent, some markers segregated as either a monoallelic duplex or a diallelic duplex, while several allelic configurations were observed in the apomictic parent. The segregation of double-dose monoallelic fragments demonstrated the tetrasomic inheritance of apomictic P. simplex. The correlations between apomixis, ploidy level, and tetrasomic inheritance are discussed.

Molecular, cytological and morpho-agronomical characterization of hexaploid somatic hybrids in Medicago.

Somatic hybrid plants produced by protoplast fusion between tetraploid Medicago sativa (2n= 4x=32) and the diploid species Medicago coerulea (2n= 2x=16) have been RFLP fingerprinted to establish their nuclear composition. Although all of the chromosomes were present, molecular analysis revealed an incomplete incorporation of the alleles of the diploid parent in the fusion products. In the polycross progeny the alleles of both parents segregated in a Mendelian mode. Cytological observations indicated that in the somatic hybrid population minor abnormalities are present; these are restricted mainly to the formation of univalents and lagging chromosomes. Meiosis appeared to be more stable than has been previously reported in the hexaploids of alfalfa. The somatic hybrids grown in the field had a rather vigorous aspect, particularly with respect to the vegetative organs. Forage yield was comparable to that of thmore productive parent. The results are discussed with a view to utilizing the somatic hybrids as starting material for breeding alfalfa at the hexaploid level.