Properties of liver glycogen isolated in density gradients of sodium iothalamate

3D Anatomy of the Quail Lumbosacral Spinal Canal-Implications for Putative Mechanosensory Function

Birds are diverse and agile vertebrates capable of aerial, terrestrial, aquatic, and arboreal locomotion. Evidence suggests that birds possess a novel balance sensing organ in the lumbosacral spinal canal, a structure referred to as the "lumbosacral organ" (LSO), which may contribute to their locomotor agility and evolutionary success. The mechanosensing mechanism of this organ remains unclear. Here we quantify the 3D anatomy of the lumbosacral region of the common quail, focusing on establishing the geometric and biomechanical properties relevant to potential mechanosensing functions. We combine digital and classic dissection to create a 3D anatomical model of the quail LSO and estimate the capacity for displacement and deformation of the soft tissues. We observe a hammock-like network of denticulate ligaments supporting the lumbosacral spinal cord, with a close association between the accessory lobes and ligamentous intersections. The relatively dense glycogen body has the potential to apply loads sufficient to pre-stress denticulate ligaments, enabling external accelerations to excite tuned oscillations in the LSO soft tissue, leading to strain-based mechanosensing in the accessory lobe neurons. Considering these anatomical features together, the structure of the LSO is reminiscent of a mass-spring-based accelerometer.

Biomass density-function relationships in suspended growth biological processes - A critical review

Good settling performance in suspended growth biomass systems, for example in activated sludge (AS) process, leads to efficient wastewater and sludge treatment. Factors that cause the differences in settleablility of AS include the morphology of bacteria, microbial community structure, and the density of bacteria and flocs. Density of AS at three levels, namely, cell, floc, and process, have been discussed here to explain the variations in AS settleability. Dense materials, inside or outside the cell, significantly increase density of AS bacteria or flocs. Functional bacteria, defined as those performing N and P removal and recovery such as phosphate accumulating organisms, nitrifiers, and anammox contain cellular inclusions that increase their density, and consequently a dense and well-settling biomass results at the process level in those systems. A density based selector of AS can be used to enrich functional bacteria in the process through the wasting and sludge age control operations in AS process. This paper critically reviews the latest literature to elucidate mechanisms of density enhancement from cell to process level, and identifies needs/strategies to improve the AS process through a biomass density selector.

Variations in cell size and buoyant density of Escherichia coli K12 during glycogen accumulation

The effect of glycogen accumulation on buoyant density and volume of Escherichia coli K12 was studied. A procedure consisting of three linear equations is presented. This requires measurement only of three parameters: cell buoyant density, cell volume and specific content of the polymer. Experimental values are then used to calculate intercepts and slopes of the equations by linear regression. From the estimated values of such parameters the in vivo values of several variables of interest can be calculated. These include in vivo density and volume of the glycogen inclusion, as well as density and volume of the structural material in the cell. The results are consistent with the glycogen inclusions being hydrated.

Mathematical model for determining the effects of intracytoplasmic inclusions on volume and density of microorganisms

Procaryotic microorganisms accumulate several polymers in the form of intracellular inclusions as a strategy to increase survival in a changing environment. Such inclusions avoid osmotic pressure increases by tightly packaging certain macromolecules into the inclusion. In the present paper, a model describing changes in volume and density of the microbial cell as a function of the weight of the macromolecule forming the inclusion is derived from simple theoretical principles. The model is then tested by linear regression with experimental data from glycogen accumulation in Escherichia coli, poly-beta-hydroxybutyrate accumulation in Alcaligenes eutrophus, and sulfur accumulation in Chromatium spp. The model predicts a certain degree of hydration of the polymer in the inclusion and explains both the linear relationship between volume of the cell and weight of the polymer and the hyperbolic relationship between density of the cell and weight of the polymer. Other implications of the model are also discussed.