Influence of altitude and enhanced ultraviolet-B radiation on tuber production, seed viability, leaf pigments and morphology in the wild potato species Solanum kurtzianum Bitter & Wittm collected from an elevational gradient.

Climate change could lead to an upward shift in plant distribution, exposing populations to higher levels of ultraviolet (UV)-B radiation. In the framework of an in situ strategy for conserving potato wild relatives, we evaluated the effect of high UV-B levels on natural population of Solanum kurtzianum. The hypothesis is that plants from naturally higher altitudes are more adapted to increased UV-B radiation. Two populations from low and high altitudes were field supplemented using UV-B-lamps (+UV-B) or excluded from it with plastic filters. Additionally, to assess in which extent the plant responses to these artificial experimental conditions are reproducible in natural conditions, three genotypes were cultivated in two mountain experimental gardens (EG) at different elevations. +UV-B treatment induced changes in leaf morphology and increases in phenolic compounds in both populations, indicating plant adaptation, since chlorophylls and reproductive structures were not negatively affected. These results indicate that this environmental factor may not limit the displacement of populations towards sites with higher UV-B levels. Meanwhile, in higher-altitude EG a tubers yield reduction, mainly through a decreased tuber number and a bigger accumulation of phenolic compounds than in +UV-B treatment were observed, suggesting that UV-B is not the only factor involved in plants adaptation to high altitude environments.

Reproductive ecology and genetic variability in natural populations of the wild potato, Solanum kurtzianum.

The cultivated potato (Solanum tuberosum ssp. tuberosum) has more than 200 related wild species distributed along the Andes, adapted to a wide range of geographical and ecological areas. Since the last century, several collection expeditions were carried out to incorporate genetic variability into the potato germplasm around the world. However, little is known about the reproductive ecology and genetic population structure of natural potato population from field studies. The aim of this work is to study, in the field, the genetic variability and reproductive strategies of populations of one of the most widely distributed potato species in Argentina, Solanum kurtzianum, growing in Mendoza province. AFLP markers showed that the genetic variability is mainly present among plants within populations, indicating that in the sampled populations, sexual reproduction is more relevant than clonal multiplication (by tubers). Additional evidence was obtained evaluating the genetic diversity in populations with a distribution in patches, where several genotypes were always detected. From a field study performed in the Villavicencio Natural Reserve, we found that the average number of plump seeds per fruit was 94.3, identified and calculated the foraging distance of four insect pollinators, and demonstrated the seed dispersal by storm water channels. We argue that the breeding system, the two modes of reproduction and the ecological interaction described here may have a prominent role in determining the genetic structure of S. kurtzianum populations, and discuss the importance of field studies on population genetics, reproductive biology and ecology to design collections and conservation strategies.

Genomic instability in Solanum tuberosum x Solanum kurtzianum interspecific hybrids.

The use of interspecific crosses in breeding is an important strategy in improving the genetic base of the modern cultivated potato, Solanum tuberosum L. Until now, it has normally been interspecific Solanum hybrids that have been morphologically and cytologically characterized. However, little is known about the genomic changes that may occur in the hybrid nucleus owing to the combination of genomes of different origin. We have observed novel AFLP bands in Solanum tuberosum x Solanum kurtzianum diploid hybrids; 40 novel fragments were detected out of 138 AFLP fragments analyzed. No cytological abnormalities were observed in the hybrids; however, we found DNA methylation changes that could be the cause of the observed genomic instabilities. Of 277 MSAP fragments analyzed, 14% showed methylation patterns that differed between the parental species and the hybrids. We also observed frequent methylation changes in the BC1 progeny. Variation patterns among F1 and BC1 plants suggest that some methylation changes occurred at random. The changes observed may have implications for potato breeding as an additional source of variability.

Straining at stool and stool frequency in free-living and institutionalised older adults.

BACKGROUND: The diagnosis of functional constipation according to Rome II criteria includes assessment of straining. However the prevalence in older adults is unknown. AIMS: To assess the prevalence of straining and its association with stool frequency in free-living (FL) and institutionalised (INS) older adults. METHODS: 50 FL subjects (mean age 74 years, range (65-97), 42% male) and 42 INS subjects (mean age 84 years, range (69-101) 36% male) were recruited. Stool frequency and straining to start and to finish were prospectively recorded by subjects for 7 consecutive days in a bowel habit diary. Statistical analyses were performed using the Chi-square or the Pearson correlation coefficient as appropriate. RESULTS: The mean stool frequency (n/week) was significantly higher (p <0.001) in the FL group compared with the INS group (11.7 and 4.9 respectively). The percentage of subjects experiencing straining to start on more than 25% of occasions was significantly lower in the FL compared with the INS group (34% and 64% respectively, chi2 = 8.4, p = 0.004, df = 1). The percentage of subjects experiencing straining to finish on more than 25% of occasions was significantly lower in the FL compared with the INS group (16% and 41% respectively, chi2 = 6.9, p = 0.009, df = 1). CONCLUSIONS: FL subjects had significantly higher stool frequency and had to strain passing a stool (to start and to finish) less often than their INS counterparts. Moreover, straining to start was experienced more often than straining to finish in both groups.

Laxative use and its relationship with straining in a London elderly population: free-living versus institutionalised.

BACKGROUND: The diagnosis of functional constipation according to Rome II criteria includes assessment of straining. However the prevalence in older adults is unknown. Moreover, laxative use increases with age, especially in the elderly. AIMS: to assess the prevalence of straining and its association with laxative use in free-living (FL) and institutionalised (INS) older adults. METHODS: 50 FL (mean age 74 years, 42% male) and 42 INS subjects (mean age 84 years, 36% male) were recruited. Straining to start and to finish defecation were prospectively recorded by subjects for 7 consecutive days in a bowel habit diary. Concurrently, the subjects recorded any laxative use during the 7 days study. Statistical analyses were performed using the Chi-square statistic. RESULTS: 20% of FL and 65% of INS subjects recorded taking laxatives during the study week. Of the 40 FL subjects not taking laxatives, 30 had to strain to start on 25% or less of occasions and 36 had to strain to finish on 25% or less of occasions (chi(2) = 7.2; p = 0.012 and chi(2) = 5.4; p = 0.041, respectively). In the INS group, although 64% of subjects taking laxatives had to strain on more than 25% of occasions, the Chi-square test was not statistically significant. CONCLUSIONS: From our results, it seems that laxatives were used appropriately in the FL, with the majority of those taking laxatives having to strain to start on more than 25% of occasions.

Uso de rFVIIA en el postoperatorio de una colecistectomía sangrante / No disponible

No disponible

A comparative study of chemical and microbiological monitoring of pollutant hydrocarbons in urban aquatic environments.

Conventional chemical and microbiological methods-aromatics by UV-fluorescence and the number of oil-degrading microorganisms, respectively-have been used for the monitoring of pollutant hydrocarbons in three different aquatic systems: two rivers, one harbour and three marine coastal areas. An evaluation of the first year data of such study is presented. Relative populations of total heterotrophic microorganisms and those of degrading hydrocarbons correlate satisfactorily with hydrocarbon concentrations in marine areas, where chronic pollution situations occur, whereas unreliable results were obtained in the river systems. The water temperature seems to have a positive influence on the response of microorganisms to oil pollution.