RESUMO
Resumen La relevancia psicológica, social y educativa del presente estudio reside en la escasez de trabajos previos que hayan evaluado el rechazo escolar en Latinoamérica y las elevadas tasas de deserción a las que se enfrentan en esta región. El objetivo de esta investigación consistió en examinar las diferencias en las puntuaciones medias de rechazo escolar y la formación de perfiles en adolescentes ecuatorianos y chilenos. Un total de 4266 estudiantes, entre 13 y 17 años de edad, procedentes de Ecuador (. = 14.83; SD = 1.86) y Chile (. = 15.23; SD = 1.26) fueron seleccionados mediante un muestreo aleatorio por conglomerados. El instrumento empleado para evaluar el rechazo escolar fue la School Refusal Assessment Scale-Revised. Las puntuaciones medias de rechazo escolar para Ecuador y Chile revelaron diferencias estadísticamente significativas de pequeña magnitud. Entre los estudiantes chilenos se registraron puntuaciones medias más altas de rechazo escolar, con el fin de captar la atención de sus seres queridos y obtener reforzadores tangibles externos a la escuela, en comparación con sus iguales procedentes de Ecuador. Los análisis de conglomerados confirmaron cuatro perfiles de rechazo escolar en ambos países: Rechazo Escolar Bajo, Rechazo Escolar Alto, Rechazo Escolar Ansioso y Rechazo Escolar Absentista. A pesar de que los adolescentes chilenos obtuvieron puntuaciones medias significativamente más altas que los ecuatorianos en algunas dimensiones del rechazo escolar, los resultados revelaron una pequeña variabilidad entre los perfiles de rechazo escolar encontrados en ambos países. Los resultados obtenidos se discuten atendiendo a las características culturales definitorias de cada uno de estos países.
Abstract School refusal behavior is defined as any child or youth's difficulty to attend classes or to remain in the school. This behavior could be based or not on anxiety and prevalence rates from 5 to 28 % if it is considered any type of rejection towards the school. Adolescents demonstrating school refusal behaviors are very likely to demonstrate poorer academic performance, more stress, behavior problems and family conflicts. The psychological, social and educational relevance of the present study is due to the scarce of previous studies that have evaluated the school refusal behavior in Latin America and the high dropout rates that they face in this region. This study is focused on two countries, Ecuador and Chile, in order to identify possible differences regarding school refusal behavior scores between adolescents in both countries. The aim of this investigation was to examine the mean differences scores on school refusal behavior and the formation of school refusal behavior profiles in Ecuadorian and Chilean adolescents to determine whether these results differ from one another based on the geographical origin. In this study participated a total of 4266 students aged between 13 and 17 years old from Ecuador (. = 14.83, SD = 1.86; N = 1588) and Chile (. = 15.23; SD = 1.26; N = 2678). These students were selected by cluster random sampling. The measure used to assess the school refusal behavior was the School Refusal Assessment Scale-Revised (SRAS-R). The SRAS-R is a self-report measure that assesses the relative strength of four proposed functions, or maintaining variables, of school refusal behavior: Factor I. Avoidance of school-based stimuli that provoke Negative Affectivity; Factor II. Escape from aversive Social/Evaluative situations at school; Factor III. Pursuit of Attention from Significant others; and Factor IV. Pursuit of Tangible Reinforcement outside of school. The SRAS-R was administered during the school day (a session of approximately 20 minutes) in groups who completed the scale anonymously in accordance with the ethical standards and also emphasizing the voluntary nature of the test. Regarding the results, mean differences scores on school refusal behavior revealed statistically significant differences of small magnitude with Chilean students reaching higher mean scores in school refusal behavior in order to pursuit the attention from significant others and to obtain tangible reinforces external to the school, in comparison with their equals from Ecuador. Cluster analysis confirmed four school refusal profiles in both countries: Low School Refusal Behavior (characterized by low school refusal behavior scores for the four factors of the SRAS-R), High School Refusal Behavior (characterized by high school refusal behavior scores for the four factors of the SRAS-R), Anxious School Refusal Behavior (profile that combines high scores on the first three factors of the SRAS-R and moderate scores for the fourth) and Absentee School Refusal Behavior (profile that combines moderate levels for the first three factors of the SRAS-R but high in the fourth factor). The results revealed a small variability between the school refusal behavior profiles across the countries. However, Chilean adolescents scored significantly higher than Ecuadorians in school refusal based on the search for tangible external reinforcements. The results of this research supported a low variability of the findings according to the country. The generalization of these results supports the transcultural validity of the SRAS-R and emphasizes that Ecuador and Chile share a similar situation regarding school refusal behavior. Some limitations of this work are considered, and they are proposed as future lines of research. To conclude, the results are discussed taking into account the defining cultural characteristics of each country.
RESUMO
Many type III-secreted effectors suppress plant defenses, but can also activate effector-triggered immunity (ETI) in resistant backgrounds. ETI suppression has been shown for a number of type III effectors (T3Es) and ETI-suppressing effectors are considered part of the arms race model for the co-evolution of bacterial virulence and plant defense. However, ETI suppression activities have been shown mostly between effectors not being naturally expressed within the same strain. Furthermore, evolution of effector families is rarely explained taking into account that selective pressure against ETI-triggering effectors may be compensated by ETI-suppressing effector(s) translocated by the same strain. The HopZ effector family is one of the most diverse, displaying a high rate of loss and gain of alleles, which reflects opposing selective pressures. HopZ effectors trigger defense responses in a variety of crops and some have been shown to suppress different plant defenses. Mutational changes in the sequence of ETI-triggering effectors have been proposed to result in the avoidance of detection by their respective hosts, in a process called pathoadaptation. We analyze how deleting or overexpressing HopZ1a and HopZ3 affects virulence of HopZ-encoding and non-encoding strains. We find that both effectors trigger immunity in their plant hosts only when delivered from heterologous strains, while immunity is suppressed when delivered from their native strains. We carried out screens aimed at identifying the determinant(s) suppressing HopZ1a-triggered and HopZ3-triggered immunity within their native strains, and identified several effectors displaying suppression of HopZ3-triggered immunity. We propose effector-mediated cross-suppression of ETI as an additional force driving evolution of the HopZ family.
RESUMO
*The Pseudomonas syringae pv syringae type III effector HopZ1a is a member of the HopZ effector family of cysteine-proteases that triggers immunity in Arabidopsis. This immunity is dependent on HopZ1a cysteine-protease activity, and independent of known resistance genes. We have previously shown that HopZ1a-triggered immunity is partially additive to that triggered by AvrRpt2. These partially additive effects could be caused by at least two mechanisms: their signalling pathways share a common element(s), or one effector interferes with the response triggered by the other. *Here, we investigate the molecular basis for the partially additive effect displayed by AvrRpt2- and HopZ1a-triggered immunities, by analysing competitive indices, hypersensitive response and symptom induction, PR-1 accumulation, expression of PR genes, and systemic acquired resistance (SAR) induction. *Partially additive effects between these defence responses require HopZ1a cysteine-protease activity, and also take place between HopZ1a and AvrRps4 or AvrRpm1-triggered responses. We establish that HopZ1a-triggered immunity is independent of salicylic acid (SA), EDS1, jasmonic acid (JA) and ethylene (ET)-dependent pathways, and show that HopZ1a suppresses the induction of PR-1 and PR-5 associated with P. syringae pv tomato (Pto)-triggered effector-triggered immunity (ETI)-like defences, AvrRpt2-triggered immunity, and Pto or Pto (avrRpt2) activation of SAR, and that suppression requires HopZ1a cysteine-protease activity. *Our results indicate that HopZ1a triggers an unusual resistance independent of known pathways and suppresses SA and EDS1-dependent resistance.
