No abstract

The senescence process is the last stage in leaf development and is characterized by dramatic changes in cellular metabolism and the degeneration of cellular structures. Several reports of senescence-associated genes (SAGs) have appeared, and an overlap in some of the genes induced during senescence and pathogen infections has been observed. For example, the enhanced expression of SAGs in response to diseases caused by fungi, bacteria, and viruses that trigger the hypersensitive response (HR) or during infections induced by virulent fungi and bacteria that elicit necrotic symptoms has been observed. The present work broadens the search for SAGs induced during compatible viral interactions with both the model plant Arabidopsis thaliana and a commercially important grapevine cultivar. The transcript profiles of Arabidopsis ecotype Uk-4 infected with tobacco mosaic virus strain Cg (TMV-Cg) and Vitis vinifera cv. Carménère infected with grapevine leafroll-associated virus strain 3 (GLRaV-3) were analysed using microarray slides of the reference species Arabidopsis. A large number of SAGs exhibited altered expression during these two compatible interactions. Among the SAGs were genes that encode proteins such as proteases, lipases, proteins involved in the mobilization of nutrients and minerals, transporters, transcription factors, proteins related to translation and antioxidant enzymes, among others. Thus, part of the plant's response to virus infection appears to be the activation of the senescence programme. Finally, it was demonstrated that several virus-induced genes are also expressed at elevated levels during natural senescence in healthy plants.

Viral diseases affect grapevine cultures without inducing any resistance response. Thus, these plants develop systemic diseases and are chronically infected. Molecular events associated with viral compatible infections responsible for disease establishment and symptoms development are poorly understood. In this study, we surveyed viral infection in grapevines at a transcriptional level. Gene expression in the Vitis vinifera red wine cultivars Carménère and Cabernet-Sauvignon naturally infected with GLRaV-3 were evaluated using a genome-wide expression profiling with the Vitis vinifera GeneChip from Affymetrix. We describe numerous genes that are induced or repressed in viral infected grapevines leaves. Changes in gene expression involved a wide spectrum of biological functions, including processes of translation and protein targeting, metabolism, transport, and cell defense. Considering cellular localization, the membrane and endomembrane systems appeared with the highest number of induced genes, while chloroplastic genes were mostly repressed. As most induced genes associated with the membranous system are involved in transport, the possible effect of virus in this process is discussed. Responses of both cultivars are analyzed and the results are compared with published data from other species. This is the first study of global gene profiling in grapevine in response to viral infections using DNA microarray.

No abstract

We use experimental data of a training program in 2005 in Colombia. We find that even up to ten years ahead, the JeA program had a positive and significant effect on the probability to work in the formal sector. Applicants in the treatment group also contributed more months to social security during the analyzed period, and to work for a large firm. Earnings of treated applicants were 11.8% higher in the whole sample, and they made larger contributions to social security. In addition, we also present non parametric bounds that for some percentiles of the sample of women, there are positive and nearly significant effects of the program. Thus, the effects of the program would have been capitalized both in increases in the likelihood of being formal, and increases in productivity. We also present evidence that the estimated program effects on the likelihood of working for the formal sector, the likelihood of working for a large firm, and the earnings in the formal sector, are not an artifact of analyzing multiple outcomes. We also find that for the whole sample of applicants, those in the treatment group have 0.315 more years of education, and have a probability of graduating from high school 10 percent higher than the control group. We find no significant effect on the probability of attending college or any school program, nor on fertility decisions, marital status or some dimensions of assortative mating. Among applicants matching to the census of the poorest population, we find that beneficiaries are more likely to participate in the labor market, to be employed, and to be enrolled in a private health insurance at the time of the survey. Finally, we find that the benefits of the JeA program are higher than it costs, leading to an internal rate of return of at least 22.1 percent. On the whole, the program was a cost-effective alternative, worth to consider to bridging the transit of youths from the informal to the formal sector in the future.