S100A6 Amyloid Fibril Formation Is Calcium-modulated and Enhances Superoxide Dismutase-1 (SOD1) Aggregation

S100A6 is a small EF-hand calcium- and zinc-binding protein involved in the regulation of cell proliferation and cytoskeletal dynamics. It is overexpressed in neurodegenerative disorders and a proposed marker for Amyotrophic Lateral Sclerosis (ALS). Following recent reports of amyloid formation by S100 proteins, we investigated the aggregation properties of S100A6. Computational analysis using aggregation predictors Waltz and Zyggregator revealed increased propensity within S100A6 helices H_I and H_IV. Subsequent analysis of Thioflavin-T binding kinetics under acidic conditions elicited a very fast process with no lag phase and extensive formation of aggregates and stacked fibrils as observed by electron microscopy. Ca²⁺ exerted an inhibitory effect on the aggregation kinetics, which could be reverted upon chelation. An FT-IR investigation of the early conformational changes occurring under these conditions showed that Ca²⁺ promotes anti-parallel β-sheet conformations that repress fibrillation. At pH 7, Ca²⁺ rendered the fibril formation kinetics slower: time-resolved imaging showed that fibril formation is highly suppressed, with aggregates forming instead. In the absence of metals an extensive network of fibrils is formed. S100A6 oligomers, but not fibrils, were found to be cytotoxic, decreasing cell viability by up to 40%. This effect was not observed when the aggregates were formed in the presence of Ca²⁺. Interestingly, native S1006 seeds SOD1 aggregation, shortening its nucleation process. This suggests a cross-talk between these two proteins involved in ALS. Overall, these results put forward novel roles for S100 proteins, whose metal-modulated aggregation propensity may be a key aspect in their physiology and function.     

Implications of goat eradication on the survivorship of the Galapagos hawk

Non-native mammals cause ecological disasters in island ecosystems and their eradication is usually considered beneficial to native biodiversity. Goats (Capra hircus) were introduced to Santiago Island, Galapagos, Ecuador, in the early 1800s, and their numbers increased to about 100,000 by 1970. A goat eradication campaign initiated in 2002 was successful, eliminating the last individuals in 2006. To evaluate the effects of goat eradication, between 1998 and 2010 we studied the Galapagos hawk (Buteo galapagoensis) population on Santiago Island before, during, and after eradication. We used a 12-year data set in a capture–mark–recapture analysis to estimate the apparent survivorship of territorial adults in 33 breeding territories, and a 5-year data set to estimate the population sizes of the floater (non-territorial) fraction of the population. Juvenile floaters showed a drastic decline starting in 2006 and continuing in 2007, 2008, and 2010, which we attribute to the completion of goat eradication in 2006, and subsequent habitat changes. We found a significant decline in adult survivorship after the goat eradication program. Additionally, group size positively affected adult survivorship in this cooperatively polyandrous raptor, presumably reflecting the benefit of shared defense and offspring provisioning during harsher conditions. The changes in the hawk population after goat eradication are an example of unforeseen consequences of a restoration program, and we hypothesize that these changes are adjustments towards a new equilibrium under the current ecosystem characteristics and capacity. © 2012 The Wildlife Society.     

Nitrogen-fixing cyanobacteria as source of phycobiliprotein pigments. Composition and growth performance of ten filamentous heterocystous strains

Ten strains of filamentous, heterocystous nitrogen-fixing blue-green algae (cyanobacteria) were screened for growth performance and tolerance to temperature, pH, irradiance and salinity, together with their potential as producers of phycobiliprotein pigments. Phycobiliproteins typically accounted for about 50% total cell protein, the prevalent type being C-phycocyanin, followed by alloppycocyanin, with levels of 17 and 11% d.wt, respectively, in some strains of Anabaena and Nostoc. C-phycoerythrin was the major pigment in several Nostoc strains, reaching 10% d.wt. Some strains represent, therefore, excellent sources of one or more phycobiliproteins. All strains tolerated an irradiance of ca 2000 μmol photon m^-2 s^-1. Anabaena sp. ATCC 33047 and Nostoc sp. (Albufera) exhibited the widest optimum range of both temperature (30–45 and 25–40 °C) and pH (6.5–9.5 and 6.0–9.0) for growth, the former also showing significant salt tolerance. In an outdoor open system, productivity of cultures of two phycoerythrin-rich strains of Nostoc was over 20 g (d.wt) m^-2 d^-1 during summer. The growth performance of the allophycocyanin-rich Anabaena sp. ATCC 33047 in outdoor semi-continuous culture has been assessed throughout the year. Productivity values under optimized conditions ranged from 9 (winter) to 24 (summer) g (d.wt) m^-2 d^-1.     

Fruit Flies in Biomedical Research

Many scientists complain that the current funding situation is dire. Indeed, there has been an overall decline in support in funding for research from the National Institutes of Health and the National Science Foundation. Within the Drosophila field, some of us question how long this funding crunch will last as it demotivates principal investigators and perhaps more importantly affects the long-term career choice of many young scientists. Yet numerous very interesting biological processes and avenues remain to be investigated in Drosophila, and probing questions can be answered fast and efficiently in flies to reveal new biological phenomena. Moreover, Drosophila is an excellent model organism for studies that have translational impact for genetic disease and for other medical implications such as vector-borne illnesses. We would like to promote a better collaboration between Drosophila geneticists/biologists and human geneticists/bioinformaticians/clinicians, as it would benefit both fields and significantly impact the research on human diseases.     

High-throughput phenotypic assessment of cardiac physiology in four commonly used inbred mouse strains

Mice with genetic alterations are used in heart research as model systems of human diseases. In the last decade there was a marked increase in the recognition of genetic diversity within inbred mouse strains. Increasing numbers of inbred mouse strains and substrains and analytical variation of cardiac phenotyping methods require reproducible, high-throughput methods to standardize murine cardiovascular physiology. We describe methods for non-invasive, reliable, easy and fast to perform echocardiography and electrocardiography on awake mice. This method can be used for primary screening of the murine cardiovascular system in large-scale analysis. We provide insights into the physiological divergence of C57BL/6N, C57BL/6J, C3HeB/FeJ and 129P2/OlaHsd mouse hearts and define the expected normal values. Our report highlights that compared to the other three strains tested C57BL/6N hearts reveal features of heart failure such as hypertrophy and reduced contractile function. We found several features of the mouse ECG to be under genetic control and obtained several strain-specific differences in cardiac structure and function.     

In vitro culture and biochemical characterization of six trypanosome isolates from Peru and Brazil

Six trypanosomatids isolated from different geographical areas from South America (Peru and Brazil) and different vectors and reservoir hosts (the triatomine Panstrongylus chinai [TP1], Triatoma infestans [TP2], Rhodnius ecuadorensis [TP3], R. prolixus [TB1], Didelphys marsupialis [TB2]), and one from a human asymptomatic patient [TB3], were characterized using lectin agglutination, isoenzyme profile, in vitro culture final metabolite patterns, and compared with a reference strain (Trypanosoma cruzi, Maracay strain [TC]). The different isolates were cultured in vitro in Grace's medium supplemented with 10% inactivated bovine foetal serum. According to our results and the statistical study, the isolate obtained from R. ecuadorensis should be designed as a Trypanosoma rangeli sp., showing all other isolates strong similarities to T. cruzi. Between them, two clusters could be identified, strongly correlating with the geographical origin. Cluster I grouped isolates from Peru and T. cruzi reference strain, and cluster II grouped the three Brazilian isolates.     

Childhood Trauma Questionnaire (CTQ) in Brazilian Samples of Different Age Groups: Findings from Confirmatory Factor Analysis

The Childhood Trauma Questionnaire (CTQ) is internationally accepted as a key tool for the assessment of childhood abuse and neglect experiences. However, there are relative few psychometric studies available and some authors have proposed two different factor solutions. We examined the dimensional structure and internal consistency of the Brazilian version of the CTQ. A total of 1,925 participants from eight different clinical and non-clinical samples including adolescents, adults and elders were considered in this study. First, we performed Confirmatory Factor Analysis to investigate the goodness of fit of the two proposed competitive factor structure models for the CTQ. We also investigated the internal consistency of all factors. Second, multi-group analyses were used to investigate measurement invariance and population heterogeneity across age groups and sex. Our findings revealed that the alternative factor structure as opposed to the original factor structure was the most appropriate model within adolescents and adults Brazilian samples. We provide further evidence for the validity and reliability of the CTQ within the Brazilian samples and report that the alternative model showed an improvement in fit indexes and may be a better alternative over the original model.     

The colonization history of Olea europaea L. in Macaronesia based on internal transcribed spacer 1 (ITS-1) sequences, randomly amplified polymorphic DNAs (RAPD), and intersimple sequence repeats (ISSR)

Phylogenetic relationships in the Olea europaea complex and the phylogeography of 24 populations of the Macaronesian olive (O. europaea ssp. cerasiformis) were assessed by using three molecular markers: nuclear ribosomal internal transcribed spacer 1 (ITS-1) sequences, randomly amplified polymorphic DNAs (RAPD), and intersimple sequence repeats (ISSR). Parsimony analysis of the ITS-1 sequences and Neighbour-joining (NJ) analyses of RAPD and ISSR banding variation revealed four major lineages in the O. europaea complex: (1) ssp. cuspidata; (2) ssp. cerasiformis from Madeira; (3) ssp. laperrinei; and (4) ssp. cerasiformis from the Canary Islands plus ssp. europaea. These results provide unequivocal support for two independent dispersal events of Olea to the Madeira and Canary Islands. Molecular and morphological evidence led to recognition of two separate olive taxa in Macaronesia, to date included in ssp. cerasiformis. NJ analyses of the combined RAPD and ISSR data suggest that the colonization of the Canaries by O. europaea may have followed an east to west stepping-stone model. An interisland dispersal sequence can be recognized, starting from the continent to Fuerteventura, Gran Canaria, Tenerife, La Gomera, and finally La Palma. High dispersal activity of the lipid-rich Olea fruits by birds in the Mediterranean region is congruent with multiple dispersal of olives to Macaronesia and successive colonization of the archipelagos. The observation of strong genetic isolation between populations of different islands of the Canary Islands suggests, however, that subsequent interisland dispersal and establishment has been very rare or may not have occurred at all.