Axons in Cat Visual Cortex are Topologically Self-similar

The axonal arbors of the different types of neocortical and thalamic neurons appear highly dissimilar when viewed in conventional 2D reconstructions. Nevertheless, we have found that their one-dimensional metrics and topologies are surprisingly similar. To discover this, we analysed the axonal branching pattern of 39 neurons (23 spiny, 13 smooth and three thalamic axons) that were filled intracellularly with horseradish peroxidase (HRP) during in vivo experiments in cat area 17. The axons were completely reconstructed and translated into dendrograms. Topological, fractal and Horton-Strahler analyses indicated that axons of smooth and spiny neurons had similar complexity, length ratios (a measure of the relative increase in the length of collateral segments as the axon branches) and bifurcation ratios (a measure of the relative increase in the number of collateral segments as the axon branches). We show that a simple random branching model (Galton-Watson process) predicts with reasonable accuracy the bifurcation ratio, length ratio and collateral length distribution of the axonal arbor

Whose Cortical Column Would that Be?

The cortical column has been an invaluable concept to explain the functional organization of the neocortex. While this idea was born out of experiments that cleverly combined electrophysiological recordings with anatomy, no one has ‘seen’ the anatomy of a column. All we know is that when we record through the cortex of primates, ungulates, and carnivores in a trajectory perpendicular to its surface there is a remarkable constancy in the receptive field properties of the neurons regarding one set of stimulus features. There is no obvious morphological analog for this functional architecture, in fact much of the anatomical data seems to challenge it. Here we describe historically the origins of the concept of the cortical column and the struggles of the pioneers to define the columnar architecture. We suggest that in the concept of a ‘canonical circuit’ we may find the means to reconcile the structure of neocortex with its functional architecture. The canonical microcircuit respects the known connectivity of the neocortex, and it is flexible enough to change transiently the architecture of its network in order to perform the required computations

Kinetics of enhanced phosphorus removal in the activated sludge process

An investigation into the removal of phosphorus in the activated sludge process showed that: (1) Luxury uptake of phosphorus may be induced by the presence of an anoxic zone (2) If a primary and secondary anoxic reactor are present in the system, the actual retention time of the primary anoxic reactor will have the dominant effect on the degree of phosphorus removal. (3) In a system where only a primary anoxic reactor is present, there is an optimum actual anoxic retention time for obtaining maximum phosphorus removal. This optimum value appears to coincide with the condition where there is no nett release of phosphorus in the anoxic zone. Decreasing or increasing the actual anoxic retention time either side of the optimum value has a detrimental effect on phosphorus removal. (4) Increasing the influent ammonia-nitrogen and hence the reactor nitrate concentration, enhances phosphorus removal. (5) An increase in aeration reactor pH to between pH 7-8 enhances phosphorus removal. (6) The mechanism of removal does not appear to be precipitation. Although an increase in pH through the anoxic reactor was observed due to denitrification, phosphorus was released into solution. (7) The degree of phosphorus removal is independent of the influent phosphorus concentration. (8) Anoxic stripping of phosphorus is not a pre-requisite for luxury uptake of phosphorus to occur. (9) The concentration of phosphorus removed is a function of the COD utilized. The ratio of phosphorus removed to the COD utilized is constant at a particular sludge age, so that as the concentration of COD utilized increases, the concentration of phosphorus removed increases. (10) The concentration of phosphorus removed is a function of the sludge age. For a fixed biodegradable influent COD, the longer the sludge age, the less phosphorus removed

Effect of Bovine Immunodeficiency-Like Virus Infection on Immune Function in Experimentally Infected Cattle

Bovine immunodeficiency-like virus (BIV) is a bovine lentivirus that has antigenic and genetic homology with the human immunodeficiency virus. Little work has been reported on the effect of BIV infection on bovine immune function. This study was designed to evaluate lymphocyte blastogenesis, mononuclear cell subset numbers, neutrophil function, hematology, and clinical signs in three groups of cattle. These groups were evaluated at 0–2 months post inoculation (PI, Group 1), 4–5 months PI (Group 2), or 19–27 months PI (Group 3). BIV infected animals were inoculated with the R-29 isolate of BIV in tissue culture cells, peripheral blood mononuclear cells from a R-29 infected calf, or a molecular clone of the R-29 isolate. Most inoculated animals seroconverted to BIV by Western immunoblot. BIV was reisolated from most of the animals inoculated. BIV infection was associated with an increase in the lymphocyte blastogenic response to the mitogen phytohemagglutinin in Groups 2 and 3. Neutrophil antibody dependent cell mediated cytotoxicity and neutrophil iodination were decreased (P\u3c0.05) in BIV infected cattle (Groups 2 and 3 and Group 3, respectively). All animals were clinically normal during the evaluation periods. Notable differences were not observed in the other assessments performed. Work with additional BIV isolates and over longer time frames is warranted

Comments and general discussion on “The anatomical problem posed by brain complexity and size: a potential solution”

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FReD: the Floral Reflectance Database - a web portal for analyses of flower colour

Background: Flower colour is of great importance in various fields relating to floral biology and pollinator behaviour. However, subjective human judgements of flower colour may be inaccurate and are irrelevant to the ecology and vision of the flower's pollinators. For precise, detailed information about the colours of flowers, a full reflectance spectrum for the flower of interest should be used rather than relying on such human assessments. Methodology/Principal Findings: The Floral Reflectance Database (FReD) has been developed to make an extensive collection of such data available to researchers. It is freely available at http://www.reflectance.co.uk. The database allows users to download spectral reflectance data for flower species collected from all over the world. These could, for example, be used in modelling interactions between pollinator vision and plant signals, or analyses of flower colours in various habitats. The database contains functions for calculating flower colour loci according to widely-used models of bee colour space, reflectance graphs of the spectra and an option to search for flowers with similar colours in bee colour space. Conclusions/Significance: The Floral Reflectance Database is a valuable new tool for researchers interested in the colours of flowers and their association with pollinator colour vision, containing raw spectral reflectance data for a large number of flower species

Differential genetic interactions of yeast stress response MAPK pathways.

Genetic interaction screens have been applied with great success in several organisms to study gene function and the genetic architecture of the cell. However, most studies have been performed under optimal growth conditions even though many functional interactions are known to occur under specific cellular conditions. In this study, we have performed a large-scale genetic interaction analysis in Saccharomyces cerevisiae involving approximately 49 × 1,200 double mutants in the presence of five different stress conditions, including osmotic, oxidative and cell wall-altering stresses. This resulted in the generation of a differential E-MAP (or dE-MAP) comprising over 250,000 measurements of conditional interactions. We found an extensive number of conditional genetic interactions that recapitulate known stress-specific functional associations. Furthermore, we have also uncovered previously unrecognized roles involving the phosphatase regulator Bud14, the histone methylation complex COMPASS and membrane trafficking complexes in modulating the cell wall integrity pathway. Finally, the osmotic stress differential genetic interactions showed enrichment for genes coding for proteins with conditional changes in phosphorylation but not for genes with conditional changes in gene expression. This suggests that conditional genetic interactions are a powerful tool to dissect the functional importance of the different response mechanisms of the cell

Screening for Type 1 Diabetes in the General Population:A Status Report and Perspective

Most screening programs to identify individuals at risk for type 1 diabetes have targeted relatives of people living with the disease to improve yield and feasibility. However, ∼90% of those who develop type 1 diabetes do not have a family history. Recent successes in disease-modifying therapies to impact the course of early-stage disease have ignited the consideration of the need for and feasibility of population screening to identify those at increased risk. Existing population screening programs rely on genetic or autoantibody screening, and these have yielded significant information about disease progression and approaches for timing for screening in clinical practice. At the March 2021 Type 1 Diabetes TrialNet Steering Committee meeting, a session was held in which ongoing efforts for screening in the general population were discussed. This report reviews the background of these efforts and the details of those programs. Additionally, we present hurdles that need to be addressed for successful implementation of population screening and provide initial recommendations for individuals with positive screens so that standardized guidelines for monitoring and follow-up can be established