The formation of the light-sensing compartment of cone photoreceptors coincides with a transcriptional switch

High-resolution daylight vision is mediated by cone photoreceptors. The molecular program responsible for the formation of their light sensor, the outer segment, is not well understood. We correlated daily changes in ultrastructure and gene expression in postmitotic mouse cones, between birth and eye opening, using serial block-face electron microscopy (EM) and RNA sequencing. Outer segments appeared rapidly at postnatal day six and their appearance coincided with a switch in gene expression. The switch affected over 14% of all expressed genes. Genes that switched off were rich in transcription factors and neurogenic genes. Those that switched on contained genes relevant for cone function. Chromatin rearrangements in enhancer regions occurred before the switch was completed, but not after. We provide a resource comprised of correlated EM, RNAseq, and ATACseq data, showing that the growth of a key compartment of a postmitotic cell involves an extensive switch in gene expression and chromatin accessibility.

Cyanide increases reduction but decreases sequestration of methylene blue by endothelial cells

The mechanisms of endothelial cell transplasma membrane electron transport (TMET) have not been completely identified. Redox probes such as methylene blue (MB) can be useful tools, but the complexity of their disposition upon exposure to the cells can hinder interpretation. For example, MB is reduced on the cell surface by TMET, but after entering the cell in reduced form, it is reoxidized and sequestered within the cell. We developed a method to separately quantify the reduction and reoxidation rates such that it can be determined whether a metabolic inhibitor such as cyanide affects the reduction or oxidation process. MB was introduced at the inlet to a column filled with endothelial cell covered beads either as a short 12 s injection (bolus) or a long 45 min infusion (pulse), and its effluent concentration was measured as a function of time. The cells extracted 56% of the MB from the bolus, but only 41% during the pulse steady state. In the presence of cyanide, these extractions increased to 70% and decreased to 4%, respectively. Mathematical model results support the interpretation that these paradoxical effects on bolus and pulse extractions reflect the differential effects of cyanide on extracellular reduction and intracellular oxidation, i.e., cyanide increased the reduction rate from 7.3 to 13.0 cm s-1 X 10(-5) and decreased the oxidation rate from 1.09 to 0.02 cm s-1 X 10(-3). Cyanide also increased intracellular NADH by almost eight times, suggesting that TMET is sensitive to the cell redox status, i.e., NADH is a direct or indirect electron source. The cyanide-induced decrease in sequestration indicates a cyanide-sensitive intracellular oxidation mechanism. The results also demonstrate the potential utility of this approach for further evaluation of these endothelial redox mechanisms.

Fathers' absence and moral development of male delinquents

To investigate the relationship between their fathers' absence and moral development, 40 urban adolescent males adjudicated as delinquents were randomly selected from a Juvenile Court population. 20 of them came from families in which fathers were absent and 20 lived with fathers present. Both groups were administered Form B of Kohlberg's Moral Judgment Interview. Statistical comparisons of the mean moral maturity scores suggested that male delinquents whose fathers were present attained higher moral maturity scores than those whose fathers were absent.

Emotional indicators in drawings of aggressive or withdrawn male delinquents

Under the assumption that similar findings by independent investigators imply a useful level of association between a feature in a drawing and a behavioral or personality trait, the human figure drawings of 200 aggressive or withdrawn male delinquents were evaluated and compared with both undifferentiated delinquents and nondelinquents with the expectation that the former groups would show a higher incidence of those features which have been associated with these respective traits. It was also hypothesized that using the features collectively would increase the accuracy of prediction over using individual characteristics. Significant differences were found for 6 of the 16 features, and predictive power was substantially increased by using all the features as indicators of their respective traits. These drawing characteristics have diagnostic value, but their relatively infrequent occurrence and the presence of most features in the drawings of all four groups require cautious clinical assessment of drawings exhibiting these features.