Dogs' expectations about occlusion events: from expectancy violation to exploration.

Previous research on human infants has shown that violations of basic physical regularities can stimulate exploration, which may represent a type of hypothesis testing aimed at acquiring knowledge about new causal relationships. In this study, we examined whether a similar connection between expectancy violation and exploration exists in nonhuman animals. Specifically, we investigated how dogs react to expectancy violations in the context of occlusion events. Throughout three experiments, dogs exhibited longer looking times at expectancy-inconsistent events than at consistent ones. This finding was further supported by pupil size analyses in the first two eye-tracking experiments. Our results suggest that dogs expect objects to reappear when they are not obstructed by a screen and consider the size of the occluding screen in relation to the occluded object. In Experiment 3, expectancy violations increased the dogs' exploration of the target object, similar to the findings with human infants. We conclude that expectancy violations can provide learning opportunities for nonhuman animals as well.

Erectile function in cardiovascular patients: its significance and a quick assessment using a visual-scale questionnaire.

PURPOSE: The aim of this study was to investigate the connection between erectile dysfunction (ED) and cardiovascular diseases and to test a novel visual-scale questionnaire (VEF) we propose for the assessment of erectile function. SUBJECTS AND METHODS: Erectile function was assessed in 170 male cardiovascular patients under the age of 70 by the use of several self-administered questionnaires: the International Index of Erectile Function-5 (IIEF-5); the Massachusetts Male Aging Study questionnaires (MMAS Sexual Activity Questionnaire and MMAS Single Question), and finally, VEF. RESULTS: Patients' mean age was 55.65 ± 9.97 y. The most common indications for hospitalization were coronary artery disease (CAD) (n = 82, 48%), and decompensated chronic heart failure (n = 30, 18%). The prevalence of ED as determined by IIEF-5 was 58% (n = 99). Patients with ED were on average 5.7 years older (P = 0.0001), had a higher frequency of diabetes (by 19%, P < 0.01), and a somewhat higher level of uric acid (by 72 µmol/l, P < 0.01). Results of the VEF correlated significantly with those of other questionnaires. Three different machine learning algorithms demonstrated a greater accuracy of VEF than IIEF-5 and MMAS Sexual Activity Questionnaire in predicting ED severity. CONCLUSION: ED is highly prevalent among cardiovascular patients. The Visual Scale Erectile Function questionnaire (VEF) is a simple and valid tool, suitable for quick screening of this condition.

Subcellular distribution of glutathione and its dynamic changes under oxidative stress in the yeast Saccharomyces cerevisiae.

Glutathione is an important antioxidant in most prokaryotes and eukaryotes. It detoxifies reactive oxygen species and is also involved in the modulation of gene expression, in redox signaling, and in the regulation of enzymatic activities. In this study, the subcellular distribution of glutathione was studied in Saccharomyces cerevisiae by quantitative immunoelectron microscopy. Highest glutathione contents were detected in mitochondria and subsequently in the cytosol, nuclei, cell walls, and vacuoles. The induction of oxidative stress by hydrogen peroxide (H(2) O(2) ) led to changes in glutathione-specific labeling. Three cell types were identified. Cell types I and II contained more glutathione than control cells. Cell type II differed from cell type I in showing a decrease in glutathione-specific labeling solely in mitochondria. Cell type III contained much less glutathione contents than the control and showed the strongest decrease in mitochondria, suggesting that high and stable levels of glutathione in mitochondria are important for the protection and survival of the cells during oxidative stress. Additionally, large amounts of glutathione were relocated and stored in vacuoles in cell type III, suggesting the importance of the sequestration of glutathione in vacuoles under oxidative stress.

Tethering of ferredoxin:NADP+ oxidoreductase to thylakoid membranes is mediated by novel chloroplast protein TROL.

Working in tandem, two photosystems in the chloroplast thylakoid membranes produce a linear electron flow from H(2)O to NADP(+). Final electron transfer from ferredoxin to NADP(+) is accomplished by a flavoenzyme ferredoxin:NADP(+) oxidoreductase (FNR). Here we describe TROL (thylakoid rhodanese-like protein), a nuclear-encoded component of thylakoid membranes that is required for tethering of FNR and sustaining efficient linear electron flow (LEF) in vascular plants. TROL consists of two distinct modules; a centrally positioned rhodanese-like domain and a C-terminal hydrophobic FNR binding region. Analysis of Arabidopsis mutant lines indicates that, in the absence of TROL, relative electron transport rates at high-light intensities are severely lowered accompanied with significant increase in non-photochemical quenching (NPQ). Thus, TROL might represent a missing thylakoid membrane docking site for a complex between FNR, ferredoxin and NADP(+). Such association might be necessary for maintaining photosynthetic redox poise and enhancement of the NPQ.

Binding behavior of amino acid conjugates of indole-3-acetic acid to immobilized human serum albumin.

The affinity of indole-3-acetic acid (IAA), indole-3-propionic acid, indole-3-butyric acid and 24 of their amino acid conjugates to immobilized human serum albumin, as expressed by the retention factor k (determined by HPLC), was dependent on (1) lipophilicity, (2) chirality and (3) functional groups in the amino acid moiety; in some cases conformation plays an additional role. Two lipophilicity-related parameters afforded quantitative correlations with k: retention on a C18 reversed-phase column (experimental approach) and the distance between the hydrophilic and hydrophobic poles of the molecules (in silico approach). Most compounds examined are possible metabolic precursors of IAA, an experimental tumor therapeutic.

Sporadic Case of Breast Angiosarcoma as a Complication of Radiotherapy Following Breast-Conserving Surgery for Invasive Ductal Breast Cancer.

BACKGROUND: Angiosarcomas are highly aggressive and malignant blood vessel tumors. Rarely, angiosarcomas develop in the breast following conservative therapy, namely radiotherapy. CASE REPORT: A 70-year-old female patient presented with dark purple discoloration of the skin of the right breast. 6 years earlier, the patient had undergone conservative surgery for invasive ductal carcinoma of the right breast. According to the breast-conserving surgery protocol, the patient had been treated with radiotherapy to the residual breast tissue. The patient's annual mammograms and ultrasound findings were normal. The skin lesion was superficially localized mostly at the border between the upper and lower medial quadrants of the breast (between 2 and 4 o'clock) and above the areola. The borders were uneven; the dimensions were 7 cm × 4 cm. The mammogram was classified as Breast Imaging Report and Data System (BI-RADS) 2. Ultrasound examination showed a well-vascularized structure, although the etiology was unclear. A tissue biopsy revealed angiosarcoma. The patient underwent radical simplex mastectomy. Following surgery, the patient underwent chemotherapy. Tests excluded metastases for a follow-up period of 5 years. CONCLUSION: Angiosarcomas that develop after radiotherapy following breast-conserving surgery are sporadic, but it is important to take this possible incident into consideration during treatment.

Subcellular distribution of glutathione and cysteine in cyanobacteria.

Glutathione plays numerous important functions in eukaryotic and prokaryotic cells. Whereas it can be found in virtually all eukaryotic cells, its production in prokaryotes is restricted to cyanobacteria and proteobacteria and a few strains of gram-positive bacteria. In bacteria, it is involved in the protection against reactive oxygen species (ROS), osmotic shock, acidic conditions, toxic chemicals, and heavy metals. Glutathione synthesis in bacteria takes place in two steps out of cysteine, glutamate, and glycine. Cysteine is the limiting factor for glutathione biosynthesis which can be especially crucial for cyanobacteria, which rely on both the sufficient sulfur supply from the growth media and on the protection of glutathione against ROS that are produced during photosynthesis. In this study, we report a method that allows detection and visualization of the subcellular distribution of glutathione in Synechocystis sp. This method is based on immunogold cytochemistry with glutathione and cysteine antisera and computer-supported transmission electron microscopy. Labeling of glutathione and cysteine was restricted to the cytosol and interthylakoidal spaces. Glutathione and cysteine could not be detected in carboxysomes, cyanophycin granules, cell walls, intrathylakoidal spaces, periplasm, and vacuoles. The accuracy of the glutathione and cysteine labeling is supported by two observations. First, preadsorption of the antiglutathione and anticysteine antisera with glutathione and cysteine, respectively, reduced the density of the gold particles to background levels. Second, labeling of glutathione and cysteine was strongly decreased by 98.5% and 100%, respectively, in Synechocystis sp. cells grown on media without sulfur. This study indicates a strong similarity of the subcellular distribution of glutathione and cysteine in cyanobacteria and plastids of plants and provides a deeper insight into glutathione metabolism in bacteria.

Transcriptional control of photosynthesis genes: the evolutionarily conserved regulatory mechanism in plastid genome function.

Chloroplast sensor kinase (CSK) is a bacterial-type sensor histidine kinase found in chloroplasts--photosynthetic plastids--in eukaryotic plants and algae. Using a yeast two-hybrid screen, we demonstrate recognition and interactions between: CSK, plastid transcription kinase (PTK), and a bacterial-type RNA polymerase sigma factor-1 (SIG-1). CSK interacts with itself, with SIG-1, and with PTK. PTK also interacts directly with SIG-1. PTK has previously been shown to catalyze phosphorylation of plastid-encoded RNA polymerase (PEP), suppressing plastid transcription nonspecifically. Phospho-PTK is inactive as a PEP kinase. Here, we propose that phospho-CSK acts as a PTK kinase, releasing PTK repression of chloroplast transcription, while CSK also acts as a SIG-1 kinase, blocking transcription specifically at the gene promoter of chloroplast photosystem I. Oxidation of the photosynthetic electron carrier plastoquinone triggers phosphorylation of CSK, inducing chloroplast photosystem II while suppressing photosystem I. CSK places photosystem gene transcription under the control of photosynthetic electron transport. This redox signaling pathway has its origin in cyanobacteria, photosynthetic prokaryotes from which chloroplasts evolved. The persistence of this mechanism in cytoplasmic organelles of photosynthetic eukaryotes is in precise agreement with the CoRR hypothesis for the function of organellar genomes: the plastid genome and its primary gene products are Co-located for Redox Regulation. Genes are retained in plastids primarily in order for their expression to be subject to this rapid and robust redox regulatory transcriptional control mechanism, whereas plastid genes also encode genetic system components, such as some ribosomal proteins and RNAs, that exist in order to support this primary, redox regulatory control of photosynthesis genes. Plastid genome function permits adaptation of the photosynthetic apparatus to changing environmental conditions of light quantity and quality.