Effect of comb age on cell measurements and worker body size

The honey bees (Apis mellifera L.) mainly use beeswax (comb) for brood rearing and food storage. Changes in the color and cell dimensions occur due to repeated food storage and brood rearing in the comb. The study aimed to determine the changes in comb cell measurements and worker body sizes in relation to comb age. For this purpose, the cell measurements of combs at age zero (wax foundation), 1, 2, 3, 4, 5, and 6 years and the body size of workers reared in them were estimated. The weight of the comb, the height of the cell base, and the weight of accumulated substances in the cell significantly increased with time. Comb age had negative effects on the cell diameter, cell depth, cell volume, cell honey or pollen capacity, and newly emerged worker body weight. Significant negative correlations were observed between the accumulated substances in a cell and the cell diameter, cell depth, and cell size, while significant positive correlations were observed among the cell volume, cell diameter, cell depth, cell honey capacity, cell pollen capacity, and worker body weight. It can be concluded that the dimensions of the comb cells and worker body size changed with the age of the comb. The obtained results recommend beekeepers to replace combs aged more than 3 years with a new comb to allow large workers to gather more nectar and pollen, rear a larger brood, and store more honey.

Computational simulator that calculates tumor control probability in a tumor heterogeneously irradiated for fractionated radiation oncology treatments

Although in the ionizing radiation field many concepts and processes are currently recognized as radiobiological, there are also probabilistic ones, and a probabilistic treatment makes a better understanding about them. The purpose of this study is to develop a new radiobiological simulator that calculates the tumor control probability (TCP) for a tumor heterogeneously irradiated from a fractioned treatment. The three possible types of cells and the results of interactions of ionizing radiation with each cell of a determined volume are analyzed. For an irradiated region with a dose per fraction d, the simulator determines the radiation biological effects using the cell kill ( K) and cell sub-lethal damage, volume, cell density, cell repair of damaged cells during the interfractions, and number of fractions. K is determined from its probabilistic complement, the cell survival ( S), described with the linear-quadratic (LQ) S(d) model as K = 1 − LQ S( d). TCP is calculated from computational simulations as in the ratio of simulations with K = 100% and their total. This application opens new avenues for theoretical and experimental investigations concerning simulations of radiation treatments, and methodologies for therapy optimizations. Our simulator represents a novel methodology as TCP is calculated without analytical formulas, but based on its own probabilistic definition.

Multi-volume hemacytometer

Cell counting has become an essential method for monitoring the viability and proliferation of cells. A hemacytometer is the standard device used to measure cell numbers in most laboratories which are typically automated to increase throughput. The principle of both manual and automated hemacytometers is to calculate cell numbers with a fixed volume within a set measurement range (105 ~ 106 cells/ml). If the cell concentration of the unknown sample is outside the range of the hemacytometer, the sample must be prepared again by increasing or decreasing the cell concentration. We have developed a new hemacytometer that has a multi-volume chamber with 4 different depths containing different volumes (0.1, 0.2, 0.4, 0.8 µl respectively). A multi-volume hemacytometer can measure cell concentration with a maximum of 106 cells/ml to a minimum of 5 × 103 cells/ml. Compared to a typical hemacytometer with a fixed volume of 0.1 µl, the minimum measurable cell concentration of 5 × 103 cells/ml on the multi-volume hemacytometer is twenty times lower. Additionally, the Multi-Volume Cell Counting model (cell concentration calculation with the slope value of cell number in multi-chambers) showed a wide measurement range (5 × 103 ~ 1 × 106 cells/ml) while reducing total cell counting numbers by 62.5% compared to a large volume (0.8 µl-chamber) hemacytometer.

Multi-Volume Hemacytometer

Cell counting has become an essential method for monitoring the viability and proliferation of cells. A hemacytometer is the standard device used to measure cell numbers in most laboratories which are typically automated to increase throughput. The principle of both manual and automated hemacytometers is to calculate cell numbers with a fixed volume within a set measurement range (105~106 cells/ml). If the cell concentration of the unknown sample is outside the range of the hemacytometer, the sample must be prepared again by increasing or decreasing the cell concentration. We have developed a new hemacytometer that has a multi-volume chamber with 4 different depths containing different volumes (0.1, 0.2, 0.4, 0.8 µl respectively). A multi-volume hemacytometer can measure cell concentration with a maximum of 106 cells/ml to a minimum of 5×103 cells/ml. Compared to a typical hemacytometer with a fixed volume of 0.1 µl, the minimum measurable cell concentration of 5×103 cells/ml on the multi-volume hemacytometer is twenty times lower. Additionally, the Multi-Volume Cell Counting model (cell concentration calculation with the slope value of cell number in multi-chambers) showed a wide measurement range (5×103 ~1×106 cells/ml) while reducing total cell counting numbers by 62.5% compared to a large volume (0.8 µl-chamber) hemacytometer.

Deeper and Deeper on the Role of BK and Kir4.1 Channels in Glioblastoma Invasiveness: A Novel Summative Mechanism?

In the last decades, increasing evidence has revealed that a large number of channel protein and ion pumps exhibit impaired expression in cancers. This dysregulation is responsible for high proliferative rates as well as migration and invasiveness, reflected in the recently coined term oncochannelopathies. In glioblastoma (GBM), the most invasive and aggressive primary brain tumor, GBM cells modify their ionic equilibrium in order to change their volume as a necessary step prior to migration. This mechanism involves increased expression of BK channels and downregulation of the normally widespread Kir4.1 channels, as noted in GBM biopsies from patients. Despite a large body of work implicating BK channels in migration in response to an artificial intracellular calcium rise, little is known about how this channel acts in GBM cells at resting membrane potential (RMP), as compared to other channels that are constitutively open, such as Kir4.1. In this review we propose that a residual fraction of functionally active Kir4.1 channels mediates a small, but continuous, efflux of potassium at the more depolarized RMP of GBM cells. In addition, coinciding with transient membrane deformation and the intracellular rise in calcium concentration, brief activity of BK channels can induce massive and rapid cytosolic water loss that reduces cell volume (cell shrinkage), a necessary step for migration within the brain parenchyma.

Geometric principles underlying the proliferation of a model cell system

SUMMARYWall deficient variants of many bacteria, called L-forms, divide by a simple mechanism that does not depend on the complex FtsZ-based cell division machine. We have used microfluidic systems to probe the growth, chromosome cycle and division mechanism of Bacillus subtilis L-forms. The results show that forcing cells into a narrow linear configuration greatly improves the efficiency of cell growth and chromosome segregation. This reinforces the view that L-form division is driven by an excess accumulation of surface area over volume. Cell geometry was also found to play a dominant role in controlling the relative positions and movement of segregating chromosomes. The presence of the nucleoid appears to influence division both via a cell volume effect and by nucleoid occlusion, even in the absence of the FtsZ machine. Overall, our results emphasise the importance of geometric effects for a range of critical cell functions and are of relevance for efforts to develop artificial or minimal cell systems.