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While recent results have provided strong evidence for the presence of a stable gut microbiota among several termite species, little is known about variations at the colony or individual level. Using a cultivation-independent approach, we investigated the structure of the bacterial community in the gut of termites from four different colonies of Hodotermes mossambicus. 16S rRNA-based terminal restriction fragment length polymorphism (T-RFLP) analysis of the bacterial gut microbiota revealed (1) a high consistency of the gut microbiota among nestmates and (2) subtle but distinct differences in community structure between individuals from different colonies. Since products of bacterial metabolism may contribute to a colony odor that can be used as discriminatory signal, the presence of a colony-specific bacterial community adds support to the hypothesis that the gut microbiota of termites is involved in nestmate recognition.

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The present study is based on a theoretical framework of cognitive load that distinguishes causal factors (learner characteristics affecting cognitive load e.g., self-concept; interest; perceived stress) and assessment factors (indicators of cognitive load e.g., mental load; mental effort; task performance) of cognitive load. Various assessment approaches have been used in empirical research to measure cognitive load during task performance. The most common methods are subjective self-reported questionnaires; only occasionally objective physiological measures such as heart rates are used. However, the convergence of subjective and objective approaches has not been extensively investigated yet, leaving unclear the meaning of each kind of measure and its validity. This study adds to this body of research by analyzing the relationship between these causal and assessment (subjective and objective) factors of cognitive load. The data come from three comparable studies in which high school students (N = 309) participated in a one-day out of school molecular biology project and completed different tasks about molecular biology structures and procedures. Heart rate variability (objective cognitive load) was measured via a chest belt. Subjective cognitive load (i.e., mental load and mental effort) and causal factors including self-concept, interest, and perceived stress were self-reported by participants on questionnaires. The findings show that a) objective heart rate measures of cognitive load are related to subjective measures of self-reported mental effort but not of mental load; b) self-reported mental effort and mental load are better predictors of task performance than objective heart rate measures of cognitive load; c) self-concept, interest and perceived stress are associated with self-reported measures of mental load and mental effort, and self-concept is associated with one of the objective heart rate measures. The findings are discussed based on the theoretical framework of cognitive load and implications for the validity of each measure are proposed.

The present study aimed to clarify the relationship between a school-specific trait (academic self-concept of ability [ASCA]) and hormonal stress response by using a trait-compatible stressor (test). First, we determined 52 students' ASCA scores for biology and measured their salivary cortisol concentration before and after a biology test (experimental group, n=28) or a free writing task (control group, n=24). For participants who took the test, statistical analysis indicated a significant negative correlation between ASCA score and cortisol response. In contrast, the control group showed a decrease in cortisol concentrations between test times and no correlation between cortisol concentration and ASCA scores were found. These findings indicated an interaction between ASCA scores and hormonal stress response when an academic-related stressor is present. Furthermore, these variables might influence each other adversely: high cortisol concentrations during a test situation may lead to greater feelings of insecurity, resulting in low ASCA scores and awareness of these low scores may lead to a further increase in cortisol, creating a vicious cycle.