The origins of individual differences in how learning is expressed in rats: a general-process perspective

Laboratory rats can exhibit marked, qualitative individual differences in the form of acquired behaviors. For example, when exposed to a signal-reinforcer relationship some rats show marked and consistent changes in sign-tracking (interacting with the signal; e.g., a lever) and others show marked and consistent changes in goal-tracking (interacting with the location of the predicted reinforcer; e.g., the food well). Here, stable individual differences in rats' sign-tracking and goal-tracking emerged over the course of training, but these differences did not generalize across different signal-reinforcer relationships (Experiment 1). This selectivity suggests that individual differences in sign- and goal-tracking reflect differences in the value placed on individual reinforcers. Two findings provide direct support for this interpretation: the palatability of a reinforcer (as measured by an analysis of lick-cluster size) was positively correlated with goal-tracking (and negatively correlated with sign-tracking); and sating rats with a reinforcer affected goal-tracking but not sign-tracking (Experiment 2). These results indicate that the observed individual differences in sign- and goal-tracking behavior arise from the interaction between the palatability or value of the reinforcer and processes of association as opposed to dispositional differences (e.g., in sensory processes, 'temperament,' or response repertoire)

Detección de anticuerpos séricos contra Toxoplasma gondii (Nicolle y Manceaux, 1909) en llamas (Lama glama Linneaus, 1758) y alpacas (Lama pacos Linneaus, 1758 ) de Chile.

Sera samples from 113 Ilamas (Lama glama) and 127 alpacas (Lama pacos) from the IX and V Regions, respectively, of Chile were tested for Toxoplasma gondii antibodies. The modified agglutination test (MAT) was used in both species and titers 1:25 were considered diagnostically significant based in previously published data. Sera from 49 lamas (43.3%) and 15 alpacas (11.8%) were positive to T. gondii. Percentaje seropositivity in serum dilutions of 1:25, 1:50, 1:500 and 1:5000 was 17.6%; 7.9%; 14.1% and 3.5% in lamas and 0%; 2.3%; 0.7% and 8.6% in alpacas, respectively. The rather low prevalence in alpacas may be associated with geographical conditions, management practices or contacts with cats rather than different species susceptibility. As expected, older animals showed higher reactivity of T. gondii than young animals.Se obtuvieron 113 sueros de llamas y 127 de alpacas de criaderos ubicados en la IX y V Regiones del país respectivamente para determinar la presencia de infección de T. gondii. Para el análisis de los sueros se utilizó el "test" modificado de aglutinación (MAT) a diluciones 1:25; 1:50, 1:500; 1:5000. Del total de 113 sueros de llamas estudiados 49 (43,3%) de ellas presentaron anticuerpos contra T. gondii, mientras que en las alpacas 15 de las 127 (11,8%) fueron positivas. El número de animales positivos en las diluciones 1/25; 1/50; 1/500; 1/5000 fue de 20 (17,6%); 9 (7,9%); 16 (10,6%); 4 (3,5%) en las llamas, respectivamente. En las alpacas los valores fueron de 0 (0%); 3 (2,3%); 1 (0,7%); 11 (8,6%), respectivamente. Aunque no existen antecedentes clínicos de la infección en los establecimientos estudiados, su potencial implicancia en este tipo de patología debería ser considerada a base de los resultados del presente trabajo que demuestra que llamas y alpacas del centro-sur de Chile son reaccionantes a la infección por T. gondii

Relationship Between Foveal Cone Specialization and Pit Morphology in Albinism

Purpose.Albinism is associated with disrupted foveal development, though intersubject variability is becoming appreciated. We sought to quantify this variability, and examine the relationship between foveal cone specialization and pit morphology in patients with a clinical diagnosis of albinism. Methods. We recruited 32 subjects with a clinical diagnosis of albinism. DNA was obtained from 25 subjects, and known albinism genes were analyzed for mutations. Relative inner and outer segment (IS and OS) lengthening (fovea-to-perifovea ratio) was determined from manually segmented spectral domain-optical coherence tomography (SD-OCT) B-scans. Foveal pit morphology was quantified for eight subjects from macular SD-OCT volumes. Ten subjects underwent imaging with adaptive optics scanning light ophthalmoscopy (AOSLO), and cone density was measured. Results. We found mutations in 22 of 25 subjects, including five novel mutations. All subjects lacked complete excavation of inner retinal layers at the fovea, though four subjects had foveal pits with normal diameter and/or volume. Peak cone density and OS lengthening were variable and overlapped with that observed in normal controls. A fifth hyper-reflective band was observed in the outer retina on SD-OCT in the majority of the subjects with albinism. Conclusions. Foveal cone specialization and pit morphology vary greatly in albinism. Normal cone packing was observed in the absence of a foveal pit, suggesting a pit is not required for packing to occur. The degree to which retinal anatomy correlates with genotype or visual function remains unclear, and future examination of larger patient groups will provide important insight on this issue

Monitoring of cfrp-strengthened reinforced concrete bridge spans in low temperature conditions

The article discusses strengthening bridges using composite materials at extreme low temperatures. Provides the results some experimental studies FRP strengthened concrete samples at low temperatures

Ataxin-1 and ataxin-2 intermediate-length PolyQ expansions in amyotrophic lateral sclerosis.

OBJECTIVE: Recent evidence suggests that intermediate-length polyglutamine (PolyQ) expansions in the ataxin-2 (ATXN-2) gene are a risk factor for amyotrophic lateral sclerosis (ALS). This work was undertaken with the aim to investigate the frequency of ataxin-1 (ATXN-1) and ATXN-2 PolyQ expansions in a cohort of patients with sporadic ALS (sALS) and patients with familial ALS (fALS) from southern Italy. METHODS: We assessed the PolyQ lengths of ATXN-1 and ATXN-2 in 405 patients with sALS, 13 patients with fALS, and 296 unrelated controls without history of neurodegenerative disorders. RESULTS: We found significantly higher intermediate PolyQ expansions ≥ 32 for ATXN-1 alleles and ≥ 28 for ATXN-2 alleles in the sALS cohort (ATXN-1: ALS, 7.07% vs controls, 2.38%; p = 0.0001; ATXN-2: ALS, 2.72% vs controls, 0.5%; p = 0.001). ATXN-1 CAT and ATXN-2 CAA interruptions were detected in patients with ALS only. Age at onset, site of onset, and sex were not significantly related to the ATXN-1 or ATXN-2 PolyQ repeat length expansions. CONCLUSIONS: Both ATXN-1 and ATXN-2 PolyQ intermediate expansions are independently associated with an increased risk for ALS

FUS MUTATIONS IN SPORADIC AMYOTROPHIC LATERAL SCLEROSIS: CLINICAL AND GENETIC ANALYSIS

Fused in sarcoma (FUS) or translocation in liposarcoma (TLS), a DNA/RNA-binding protein, causes a dominant autosomal inherited form of amyotrophic lateral sclerosis (ALS), ALS 6. Its main role in neurodegeneration is highlighted by the presence of cytoplasmic accumulation of its mutant protein form in ALS patients. To further define the frequency and spectrum of FUS gene mutations, we have performed a molecular screening of a cohort of 327 Italian patients from Southern Italy with sporadic ALS (SALS). We identified 4 patients carrying 3 different missense mutations and several polymorphisms. Two different substitutions occurring in the same amino acidic position have been observed in 2 patients: R521G and R521C respectively; P525L mutation has been found in 2 additional cases. Most of the patients with FUS mutations showed early symptom onset and had short disease survival. We also detected 4 different polymorphic variants (3=-untranslated region [UTR] variant, c.*41G.A; c.52313ins[GAGGTG]; c.335-15del[TTTT]; and rs13331793) in 9 patients from within our cohort. This study underlines the importance of population-based mutation screening of newly identified genes. \ua9 2011 Elsevier Inc. All rights reserved

EZ spheres: a stable and expandable culture system for the generation of pre-rosette multipotent stem cells from human ESCs and iPSCs

We have developed a simple method to generate and expand multipotent, self-renewing pre-rosette neural stem cells from both human embryonic stem cells (hESCs) and human induced pluripotent stem cells (iPSCs) without utilizing embryoid body formation, manual selection techniques, or complex combinations of small molecules. Human ESC and iPSC colonies were lifted and placed in a neural stem cell medium containing high concentrations of EGF and FGF-2. Cell aggregates (termed EZ spheres) could be expanded for long periods using a chopping method that maintained cell-cell contact. Early passage EZ spheres rapidly down-regulated OCT4 and up-regulated SOX2 and nestin expression. They retained the potential to form neural rosettes and consistently differentiated into a range of central and peripheral neural lineages. Thus, they represent a very early neural stem cell with greater differentiation flexibility than other previously described methods. As such, they will be useful for the rapidly expanding field of neurological development and disease modeling, high-content screening, and regenerative therapies based on pluripotent stem cell technology