Expression of Transposable Elements in Neural Tissues during Xenopus Development

Transposable elements comprise a large proportion of animal genomes. Transposons can have detrimental effects on genome stability but also offer positive roles for genome evolution and gene expression regulation. Proper balance of the positive and deleterious effects of transposons is crucial for cell homeostasis and requires a mechanism that tightly regulates their expression. Herein we describe the expression of DNA transposons of the Tc1/mariner superfamily during Xenopus development. Sense and antisense transcripts containing complete Tc1-2_Xt were detected in Xenopus embryos. Both transcripts were found in zygotic stages and were mainly localized in Spemann's organizer and neural tissues. In addition, the Tc1-like elements Eagle, Froggy, Jumpy, Maya, Xeminos and TXr were also expressed in zygotic stages but not oocytes in X. tropicalis. Interestingly, although Tc1-2_Xt transcripts were not detected in Xenopus laevis embryos, transcripts from other two Tc1-like elements (TXr and TXz) presented a similar temporal and spatial pattern during X. laevis development. Deep sequencing analysis of Xenopus tropicalis gastrulae showed that PIWI-interacting RNAs (piRNAs) are specifically derived from several Tc1-like elements. The localized expression of Tc1-like elements in neural tissues suggests that they could play a role during the development of the Xenopus nervous system

Subcortical volumes across the lifespan: Data from 18,605 healthy individuals aged 3-90 years

Age has a major effect on brain volume. However, the normative studies available are constrained by small sample sizes, restricted age coverage and significant methodological variability. These limitations introduce inconsistencies and may obscure or distort the lifespan trajectories of brain morphometry. In response, we capitalized on the resources of the Enhancing Neuroimaging Genetics through Meta-Analysis (ENIGMA) Consortium to examine age-related trajectories inferred from cross-sectional measures of the ventricles, the basal ganglia (caudate, putamen, pallidum, and nucleus accumbens), the thalamus, hippocampus and amygdala using magnetic resonance imaging data obtained from 18,605 individuals aged 3-90 years. All subcortical structure volumes were at their maximum value early in life. The volume of the basal ganglia showed a monotonic negative association with age thereafter; there was no significant association between age and the volumes of the thalamus, amygdala and the hippocampus (with some degree of decline in thalamus) until the sixth decade of life after which they also showed a steep negative association with age. The lateral ventricles showed continuous enlargement throughout the lifespan. Age was positively associated with inter-individual variability in the hippocampus and amygdala and the lateral ventricles. These results were robust to potential confounders and could be used to examine the functional significance of deviations from typical age-related morphometric patterns

Dynamics of experimental populations of native and introduced blowflies (Diptera: Calliphoridae): mathematical modelling and the transition from asymptotic equilibrium to bounded oscillations

The equilibrium dynamics of native and introduced blowflies is modelled using a density-dependent model of population growth that takes into account important features of the life-history in these flies. A theoretical analysis indicates that the product of maximum fecundity and survival is the primary determinant of the dynamics. Cochliomyia macellaria, a blowfly native to the Americas and the introduced Chrysomya megacephala and Chrysomya putoria, differ in their dynamics in that the first species shows a damping oscillatory behavior leading to a one-point equilibrium, whereas in the last two species population numbers show a two-point limit cycle. Simulations showed that variation in fecundity has a marked effect on the dynamics and indicates the possibility of transitions from one-point equilibrium to bounded oscillations and aperiodic behavior. Variation in survival has much less influence on the dynamics

Diferenças na apresentação clínico-radiológica da tuberculose intratorácica segundo a presença ou não de infecção por HIV Differences in the clinical and radiological presentation of intrathoracic tuberculosis in the presence or absence of HIV infection

OBJETIVO: Descrever as diferenças na apresentação clínico-radiológica da tuberculose segundo a presença ou não de infecção por HIV. MÉTODOS: Examinou-se uma amostra consecutiva de 231 adultos com tuberculose pulmonar bacilífera internados em hospital de tisiologia. A presença de infecção por HIV, AIDS e fatores associados foi avaliada e as radiografias de tórax foram reinterpretadas. RESULTADOS: Havia 113 pacientes HIV-positivos (49%). Estes pacientes apresentavam maior freqüência de tuberculose pulmonar atípica (lesões pulmonares associadas a linfonodomegalias intratorácicas), tuberculose de disseminação hemática e tuberculose pulmonar associada a linfonodomegalias superficiais e menor freqüência de lesões pulmonares escavadas do que os pacientes HIV-negativos. Isto também ocorreu entre os pacientes HIV-positivos com AIDS e os HIV-positivos sem AIDS. Não se observaram diferenças entre os pacientes HIV-positivos sem AIDS e os HIV-negativos. Os valores medianos de CD4 foram menores nos pacientes HIV-positivos com linfonodomegalias intratorácicas e lesões pulmonares em comparação aos com lesões pulmonares exclusivas (47 vs. 266 células/mm³; p < 0,0001), nos pacientes HIV-positivos com AIDS em comparação aos HIV-positivos sem AIDS (136 vs. 398 células/mm³; p < 0,0001) e nos pacientes com tuberculose pulmonar atípica em comparação aos com outros tipos de tuberculose (31 vs. 258 células/mm³; p < 0,01). CONCLUSÃO: Há um predomínio de formas atípicas e doença disseminada entre pacientes com imunossupressão avançada. Em locais com alta prevalência de tuberculose, a presença de tuberculose pulmonar atípica ou de tuberculose pulmonar associada a linfonodomegalias superficiais é definidora de AIDS.<br>OBJECTIVE: To describe the differences in the clinical and radiological presentation of tuberculosis in the presence or absence of HIV infection. METHODS: A sample of 231 consecutive adults with active pulmonary tuberculosis admitted to a tuberculosis hospital were studied, assessing HIV infection, AIDS, and associated factors, as well as re-evaluating chest X-rays. RESULTS: There were 113 HIV-positive patients (49%) Comparing the 113 HIV-positive patients (49%) to the 118 HIV-negative patients (51%), the former presented a higher frequency of atypical pulmonary tuberculosis (pulmonary lesions accompanied by intrathoracic lymph node enlargement), hematogenous tuberculosis, and pulmonary tuberculosis accompanied by superficial lymph node enlargement, as well as presenting less pulmonary cavitation. The same was found when HIV-positive patients with AIDS were compared to those without AIDS. There were no differences between the HIV-positive patients without AIDS and the HIV-negative patients. Median CD4 counts were lower in HIV-positive patients with intrathoracic lymph node enlargement and pulmonary lesions than in the HIV-positive patients with pulmonary lesions only (47 vs. 266 cells/mm³; p < 0.0001), in HIV-positive patients with AIDS than in those without AIDS (136 vs. 398 cells/mm³; p < 0.0001) and in patients with atypical pulmonary tuberculosis than in those with other forms of tuberculosis (31 vs. 258 cells/mm³; p < 0.01). CONCLUSION: Atypical forms and disseminated disease predominate among patients with advanced immunosuppression. In regions where TB prevalence is high, the presence of atypical pulmonary tuberculosis or pulmonary tuberculosis accompanied by superficial lymph node enlargement should be considered an AIDS-defining condition

Spatio-temporal dynamics and transition from asymptotic equilibrium to bounded oscillations in Chrysomya albiceps (Diptera, Calliphoridae)

The sensitivity of parameters that govern the stability of population size in Chrysomya albiceps and describe its spatial dynamics was evaluated in this study. The dynamics was modeled using a density-dependent model of population growth. Our simulations show that variation in fecundity and mainly in survival has marked effect on the dynamics and indicates the possibility of transitions from one-point equilibrium to bounded oscillations. C. albiceps exhibits a two-point limit cycle, but the introduction of diffusive dispersal induces an evident qualitative shift from two-point limit cycle to a one fixed-point dynamics. Population dynamics of C. albiceps is here compared to dynamics of Cochliomyia macellaria, C. megacephala and C. putoria