The Dynamics of Cryptococcus neoformans Cell and Transcriptional Remodeling during Infection.

The phenotypic plasticity of Cryptococcus neoformans is widely studied and demonstrated in vitro, but its influence on pathogenicity remains unclear. In this study, we investigated the dynamics of cryptococcal cell and transcriptional remodeling during pulmonary infection in a murine model. We showed that in Cryptococcus neoformans, cell size reduction (cell body ≤ 3 µm) is important for initial adaptation during infection. This change was associated with reproductive fitness and tissue invasion. Subsequently, the fungus develops mechanisms aimed at resistance to the host's immune response, which is determinant for virulence. We investigated the transcriptional changes involved in this cellular remodeling and found an upregulation of transcripts related to ribosome biogenesis at the beginning (6 h) of infection and a later (10 days) upregulation of transcripts involved in the inositol pathway, energy production, and the proteasome. Consistent with a role for the proteasome, we found that its inhibition delayed cell remodeling during infection with the H99 strain. Altogether, these results further our understanding of the infection biology of C. neoformans and provide perspectives to support therapeutic and diagnostic targets for cryptococcosis.

Expression and Functional Analyses of the WIP Gene Family in Arabidopsis.

The WIP family of transcription factors comprises the A1d subgroup of C2H2 zinc finger proteins. This family has six members in Arabidopsis thaliana and most of the known functions have been described by analyzing single knockout mutants. However, it has been shown that WIP2 and its closest paralogs WIP4 and WIP5 have a redundant and essential function in root meristems. It is likely that these and other WIP genes perform more, still unknown, functions. To obtain hints about these other functions, the expression of the six WIP genes was explored. Moreover, phenotypic ana-lyses of overexpressors and wip mutants revealed functions in modulating organ and cell size, stomatal density, and vasculature development.

Computational and theoretical insights into the homeostatic response to the decreased cell size of midbrain dopamine neurons.

Midbrain dopamine neurons communicate signals of reward anticipation and attribution of salience. This capacity is distorted in heroin or cocaine abuse or in conditions such as human mania. A shared characteristic among rodent models of these behavioral disorders is that dopamine neurons in these animals acquired a small size and manifest an augmented spontaneous and burst activity. The biophysical mechanism underlying this increased excitation is currently unknown, but is believed to primarily follow from a substantial drop in K+ conductance secondary to morphology reduction. This work uses a dopamine neuron mathematical model to show, surprisingly, that under size diminution a reduction in K+ conductance is an adaptation that attempts to decrease cell excitability. The homeostatic response that preserves the intrinsic activity is the conservation of the ion channel density for each conductance; a result that is analytically demonstrated and challenges the experimentalist tendency to reduce intrinsic excitation to K+ conductance expression level. Another unexpected mechanism that buffers the raise in intrinsic activity is the presence of the ether-a-go-go-related gen K+ channel since its activation is illustrated to increase with size reduction. Computational experiments finally demonstrate that size attenuation results in the paradoxical enhancement of afferent-driven bursting as a reduced temporal summation indexed correlates with improved depolarization. This work illustrates, on the whole, that experimentation in the absence of mathematical models may lead to the erroneous interpretation of the counterintuitive aspects of empirical data.

Quantitative Cellular Evaluation and Anatomical Organization of the External Region of Different Genetic Materials and Maturation Stages of Tomato Processing

Abstract The effect of the anatomical structure of tomato skin may be significant for quality determination at the harvest point, but the definitions of cells that constitute the skin of fleshy fruits, such as tomato, are still unclear, providing contradictory descriptions. The aim of this study was to evaluate the epidermal tissue of different genetic materials of tomato processing (IT761, U2006, TC2736, CVR2909 and F3060) and maturation stage, in order to compare and choose genetic materials with morphological characteristics of the epidermis region more appropriate for the bulk transport. Micrographs were used for cell measurements using the Image J software. Cuticle undergoes thickening during fruit growth, and reduction in full maturation. Genetic materials presenting fruits with thicker cuticle at the harvest stage (CVR2909, F3060 and IT761) were more advantageous due to their mechanical resistance. Cuticle deposition ends before full fruit maturation, resulting in a decrease in the amount of cutin per surface unit, consequently decreasing cuticle thickness in the ripe fruit. The characteristics observed in the tomato fruit mesocarp clearly showed the disruption of the cell wall during the fourth maturation stage related to loss of fruit firmness. Among the new genetic materials, F3060 has a greater potential to become cultivated for industrialization due to its morphological characteristics, such as elevated cuticle thickness and high values for width, height, perimeter and area of epidermal cells in full maturation stage, which make it suitable for bulk transport.

Influence of carbon source on cell size and production of anti LDL (-) single-chain variable fragment by a recombinant Pichia pastoris strain.

The aim of this work was to study the effect of the carbon source (glycerol, sucrose, glucose or a sucrose/glucose mixture) on the production of the anti LDL (-) single-chain variable fragment (scFv) by the recombinant Pichia pastoris SMD 1168 strain as well as on the cell size. The use of glucose as a carbon source in the growth phase led to a remarkable increase in cell size compared with glycerol, while the smallest cells were obtained with sucrose likely due to the occurrence of an energetic stress. The scFv concentration seemed to be related to cell number rather than to cell concentration, which in its turn showed no significant dependence on the carbon source. Yeast cells grown on sucrose had a mean diameter (0.736 ± 0.097 µm) about 35% shorter than those grown on glucose and allowed for the highest final concentration of the scFv antibody fragment (93.7 ± 0.2 mg/L). These results demonstrate that sucrose is the best carbon source for the expression of such an antibody fragment by the recombinant P. pastoris strain, which may be very useful for the diagnostic analysis of the so-called "bad cholesterol".

Selecting the right gate to identify relevant cells for your assay: a study of thioglycollate-elicited peritoneal exudate cells in mice.

OBJECTIVE: In this study, we investigate the diversity and modulation of leukocyte populations represented in the gates defined by size and granularity at different time points of thioglycollate-induced peritonitis in mouse. RESULTS: The inflammatory cells were distributed into four regions (R1-R4) of a data plot graph defined by cell size and granularity. R1 and R2 contained agranular cells that were small in size and predominately included T (CD3+) lymphocytes along with B (B220+) lymphocytes. Macrophages (F4/80+) were the predominant cells found in the R3 region. However, these cells were present in all regions, albeit at a lower frequency in R1 and R2. Granulocytes (Gr1+) were mainly distributed in R3 and R4. The wide distribution of F4/80+ and Gr1+ cells may reflect the recruitment and activation state of the different macrophage and granulocyte populations. Based on these observations, size and granularity may contribute to an initial step in the analysis and sorting of thioglycollate-elicited peritoneal exudate cells. However, the developmental stage and cell activation state may interfere with cell segregation using size and granularity as parameters.

RSL4 Takes Control: Multiple Signals, One Transcription Factor.

Root hair growth dramatically expands the root surface area, thus facilitating water and nutrient uptake. Until recently, the molecular mechanism underlying root hair growth was unknown. Recent studies have revealed that the transcription factor ROOT HAIR DEFECTIVE 6 LIKE 4 (RSL4) coordinates hormonal, environmental, and developmental factors to trigger polar growth.

ZO-2, a tight junction protein involved in gene expression, proliferation, apoptosis, and cell size regulation.

ZO-2 is a peripheral tight junction protein that belongs to the membrane-associated guanylate kinase protein family. Here, we explain the modular and supramodular organization of ZO-2 that allows it to interact with a wide variety of molecules, including cell-cell adhesion proteins, cytoskeletal components, and nuclear factors. We also describe how ZO proteins evolved through metazoan evolution and analyze the intracellular traffic of ZO-2, as well as the roles played by ZO-2 at the plasma membrane and nucleus that translate into the regulation of proliferation, cell size, and apoptosis. In addition, we focus on the impact of ZO-2 expression on male fertility and on maladies like cancer, cholestasis, and hearing loss.

Corrigendum: Brain scaling in mammalian evolution as a consequence of concerted and mosaic changes in numbers of neurons and average neuronal cell size.

[This corrects the article on p. 77 in vol. 8, PMID: 25157220.].

Corrigendum: Cellular scaling rules for the brain of Artiodactyla include a highly folded cortex with few neurons.

[This corrects the article on p. 128 in vol. 8, PMID: 25429261.].

All brains are made of this: a fundamental building block of brain matter with matching neuronal and glial masses.

How does the size of the glial and neuronal cells that compose brain tissue vary across brain structures and species? Our previous studies indicate that average neuronal size is highly variable, while average glial cell size is more constant. Measuring whole cell sizes in vivo, however, is a daunting task. Here we use chi-square minimization of the relationship between measured neuronal and glial cell densities in the cerebral cortex, cerebellum, and rest of brain in 27 mammalian species to model neuronal and glial cell mass, as well as the neuronal mass fraction of the tissue (the fraction of tissue mass composed by neurons). Our model shows that while average neuronal cell mass varies by over 500-fold across brain structures and species, average glial cell mass varies only 1.4-fold. Neuronal mass fraction varies typically between 0.6 and 0.8 in all structures. Remarkably, we show that two fundamental, universal relationships apply across all brain structures and species: (1) the glia/neuron ratio varies with the total neuronal mass in the tissue (which in turn depends on variations in average neuronal cell mass), and (2) the neuronal mass per glial cell, and with it the neuronal mass fraction and neuron/glia mass ratio, varies with average glial cell mass in the tissue. We propose that there is a fundamental building block of brain tissue: the glial mass that accompanies a unit of neuronal mass. We argue that the scaling of this glial mass is a consequence of a universal mechanism whereby numbers of glial cells are added to the neuronal parenchyma during development, irrespective of whether the neurons composing it are large or small, but depending on the average mass of the glial cells being added. We also show how evolutionary variations in neuronal cell mass, glial cell mass and number of neurons suffice to determine the most basic characteristics of brain structures, such as mass, glia/neuron ratio, neuron/glia mass ratio, and cell densities.

Brain scaling in mammalian evolution as a consequence of concerted and mosaic changes in numbers of neurons and average neuronal cell size.

Enough species have now been subject to systematic quantitative analysis of the relationship between the morphology and cellular composition of their brain that patterns begin to emerge and shed light on the evolutionary path that led to mammalian brain diversity. Based on an analysis of the shared and clade-specific characteristics of 41 modern mammalian species in 6 clades, and in light of the phylogenetic relationships among them, here we propose that ancestral mammal brains were composed and scaled in their cellular composition like modern afrotherian and glire brains: with an addition of neurons that is accompanied by a decrease in neuronal density and very little modification in glial cell density, implying a significant increase in average neuronal cell size in larger brains, and the allocation of approximately 2 neurons in the cerebral cortex and 8 neurons in the cerebellum for every neuron allocated to the rest of brain. We also propose that in some clades the scaling of different brain structures has diverged away from the common ancestral layout through clade-specific (or clade-defining) changes in how average neuronal cell mass relates to numbers of neurons in each structure, and how numbers of neurons are differentially allocated to each structure relative to the number of neurons in the rest of brain. Thus, the evolutionary expansion of mammalian brains has involved both concerted and mosaic patterns of scaling across structures. This is, to our knowledge, the first mechanistic model that explains the generation of brains large and small in mammalian evolution, and it opens up new horizons for seeking the cellular pathways and genes involved in brain evolution.

The glia/neuron ratio: how it varies uniformly across brain structures and species and what that means for brain physiology and evolution.

It is a widespread notion that the proportion of glial to neuronal cells in the brain increases with brain size, to the point that glial cells represent "about 90% of all cells in the human brain." This notion, however, is wrong on both counts: neither does the glia/neuron ratio increase uniformly with brain size, nor do glial cells represent the majority of cells in the human brain. This review examines the origin of interest in the glia/neuron ratio; the original evidence that led to the notion that it increases with brain size; the extent to which this concept can be applied to white matter and whole brains and the recent supporting evidence that the glia/neuron ratio does not increase with brain size, but rather, and in surprisingly uniform fashion, with decreasing neuronal density due to increasing average neuronal cell size, across brain structures and species. Variations in the glia/neuron ratio are proposed to be related not to the supposed larger metabolic cost of larger neurons (given that this cost is not found to vary with neuronal density), but simply to the large variation in neuronal sizes across brain structures and species in the face of less overall variation in glial cell sizes, with interesting implications for brain physiology. The emerging evidence that the glia/neuron ratio varies uniformly across the different brain structures of mammalian species that diverged as early as 90 million years ago in evolution highlights how fundamental for brain function must be the interaction between glial cells and neurons.

Produção de couve-brócolo em função do tipo de bandeja e idade das mudas / Broccoli production in function of container type and seedling age

O experimento foi realizado de março a agosto de 2005, na FCA/UNESP em São Manuel (SP) e objetivou-se com este trabalho estudar os efeitos dos tipos de bandeja de poliestireno expandido com 128 e 200 células e das idades das mudas de 32, 39, 46 e 53 dias após a semeadura no transplantio sobre a produção de couve-brócolo 'Legacy'. O delineamento experimental foi em blocos ao acaso, com oito repetições. Foram avaliados, por ocasião da colheita, a massa e o diâmetro da "cabeça" e o número de folhas por planta. Observou-se que os tipos de bandejas e as idades das mudas não influenciaram a massa e o diâmetro da "cabeça", bem como o número de folhas por planta.

The experiment was carried out from March to August 2005, at FCA/UNESP in São Manuel, São Paulo State. The purpose of the present research was to study the effects of type of extended polystyrene trays with 128 and 200 cells and seedling ages of 32, 39, 46 and 53 days after sowing at transplanting in the production of broccoli 'Legacy'. The experimental outline was in randomized blocks, with eight replications. Head weight and diameter and leave number per plant were evaluated. It was observed that container type and seedlings age didn't influence the head weight and diameter and the leave number per plant.