Spontaneous resurgence of conditioned fear weeks after successful extinction in brain injured mice.

Mild traumatic brain injury (TBI) is a major risk factor for post-traumatic stress disorder (PTSD), and both disorders share common symptoms and neurobiological defects. Relapse after successful treatment, known as long-term fear resurgence, is common in PTSD patients and a major therapeutic hurdle. We induced a mild focal TBI by controlled cortical impact (CCI) in male C57BL/6 J mice and used fear conditioning to assess PTSD-like behaviors and concomitant alterations in the fear circuitry. We found for the first time that mild TBI, and to a lesser extent sham (craniotomy), mice displayed a spontaneous resurgence of conditioned fear when tested for fear extinction memory recall, despite having effectively acquired and extinguished conditioned fear 6 weeks earlier in the same context. Other characteristic symptoms of PTSD are risk-taking behaviors and cognitive deficits. CCI mice displayed risk-taking behaviors, behavioral inflexibility and reductions in processing speed compared to naïve mice. In conjunction with these changes there were alterations in amygdala morphology 3 months post-trauma, and decreased myelin basic protein density at the primary lesion site and in distant secondary sites such as the hippocampus, thalamus, and amygdala, compared to sham mice. Furthermore, activity-dependent brain-derived neurotrophic factor (BDNF) transcripts were decreased in the prefrontal cortex, a key region for fear extinction consolidation, following fear extinction training in both TBI and, to a lesser extent, sham mice. This study shows for the first time that a mild brain injury can generate a spontaneous resurgence of conditioned fear associated with defective BDNF signalling in the prefrontal cortex, PTSD-like behaviors, and have enduring effects on the brain.

Allelic Variability in the Intronic Region of the Fibroin Heavy-Chain Gene in Silkworm Bombyx mori L. Strains of Brazilian Germplasm Bank.

The domesticated silkworm Bombyx mori L. is currently found only in germplasm banks. Therefore, characterization and conservation of this genetic resource is crucial. Based on previous studies that revealed nucleotide differences in silkworm strains, the intron of the fibroin heavy chain gene (H-fib) can be used for molecular silkworm characterization. The H-fib gene has two exons and a unique intron, and encodes the principal component of the silk fiber, the fibroin heavy chain. Therefore, this study aimed to identify the genetic variability of the unique intron of H-fib gene of 20 silkworm strains maintained at the Universidade Estadual de Maringá Brazilian Germplasm Bank (UBGB) by conformation-sensitive gel electrophoresis (CSGE) and nucleotide sequencing. Genomic DNA extracted from silkworm moths was PCR amplified. CSGE revealed that most of the analyzed silkworm strains had only homoduplex molecules. However, DNA from the Japanese strains B106, B82, and M12-2 had two extra DNA fragments produced by heteroduplex molecules, revealing variation between alleles. Sequencing of the H-fib intron was used to confirm the variation previously detected by CSGE and detected a significant polymorphism characterized by a 17-base pair (bp) deletion, a 2-bp insertion, and eight nucleotide substitutions. Although genetic and allelic variability was detected in some silkworm strains, the intron of the H-fib gene revealed not to be the best molecular marker for the characterization of B. mori strains from UBGB.

Biological and molecular characterization of silkworm strains from the Brazilian germplasm bank of Bombyx mori.

Brazil has only one public genetic pool of Bombyx mori strains, which was established in 2005 at Universidade Estadual de Maringá, Maringá, Paraná State. This genetic bank has been maintained, and the strains have been characterized using genetic and morphological tools. The quantitative and qualitative traits, directly or indirectly related to productivity, were evaluated in 14 silkworm strains. In addition to biological and productivity analyses, DNA markers related to susceptibility to the B. mori nucleopolyhedrovirus (BmNPV) were analyzed. BmNPV is a major cause of production loss and is a serious problem for Paraná sericulture. The silkworm strains from diverse geographic origins were found to have different characteristics, including body weight, larval stage duration, cocoon weight, and other biological traits. In terms of productivity, the raw silk percentages were almost uniform, with an overall average of 16.28%. Overall, the Chinese strain C37 gave the best performance in many of the quantitative traits, and it surpassed the other strains in productivity traits. Therefore, it can be used as one of the strains that compose the elite germplasm for silkworm breeding programs. Additionally, genetic molecular markers were efficient in discriminating between B. mori strains that had been identified based on their geographical origin. We found that all Japanese strains produced a 400-bp molecular marker that has been associated with susceptibility to BmNPV.

The stone decay of monuments in relation to atmospheric environment.

In order to explain why different forms of decay are present on a building facade some samples were taken from different areas of many monuments. Macroscopic observations of the forms of decay were correlated with quantitative analytical data in order to build up a simple model which was able to explain in a general way the decay phenomena. This simplified model was tested on several Venetian monuments and the features visible on stone surfaces correspond to different degree of deterioration. The quantitative analytical data were associated with the different forms of decay, which were defined as white washing, dirt accumulation and dirt washing. The results obtained showed that the features visible on stone surfaces corresponded to different degree of deterioration and the sulphate formation is greatest in the black dendrite-shaped crusts which are generally formed at the interface between the white washing areas and the sheltered ones, which were defined as dirt washing area.