Bacteria arise at the border of mycoplasma-infected HeLa cells, containing cytoplasm with either malformed cytosol, mitochondria and endoplasmic reticulum or tightly adjoined smooth vacuoles

A study with transmission electron microscopy of mycoplasma-contaminated HeLa cells using five cell donors referred to as donors A, B, C, D and E, observations are herein presented. Experiments performed with cells from donors B, C and D, revealed the presence of Mycoplasma hyorhinis after PCR and sequencing experiments. Bacteria probably originated from a cytoplasm with compacted tiny granular particles replacing the normal cytosol territories, or from the contact with the cytoplasm through a clear semi-solid material. The compact granularity (CG) of the cytoplasm was crossed by stripes of smooth and rough endoplasmic reticulum cisternae. Among apparently normal mitochondria, it was noted, in variable proportions, mitochondria with crista-delimited lucent central regions that expand to and occupied the interior of a crista-less organelle, which can undergo fission. Other components of the scenarios of mycoplasma-induced cell demolition are villus-like structures with associated 80-200 nm vesicles and a clear, flexible semi-solid, process-sensitive substance that we named jam-like material. This material coated the cytoplasmic surface, its recesses, irregular protrusions and detached cytoplasmic fragments. It also cushioned forming bacteria. Cyst-like structures were often present in the cytoplasm. Cells, mainly apoptotic, exhibiting ample cytoplasmic sectors with characteristic net-like profile due to adjoined vacuoles, as well as ovoid or elongated profiles, consistently appeared in all cells from the last four cell donors. These cells were named “modified host cells” because bacteria arose in the vacuoles. The possibility that, in some samples, there was infection and/or coinfection of the host cell by another organism(s) cannot be ruled out

Immunoregulation of bovine macrophages by factors in the salivary glands of Rhipicephalus microplus

<p>Abstract</p> <p>Background</p> <p>Alternative strategies are required to control the southern cattle tick, <it>Rhipicephalus microplus</it>, due to evolving resistance to commercially available acaricides. This invasive ectoparasite is a vector of economically important diseases of cattle such as bovine babesiosis and anaplasmosis. An understanding of the biological intricacies underlying vector-host-pathogen interactions is required to innovate sustainable tick management strategies that can ultimately mitigate the impact of animal and zoonotic tick-borne diseases. Tick saliva contains molecules evolved to impair host innate and adaptive immune responses, which facilitates blood feeding and pathogen transmission. Antigen presenting cells are central to the development of robust T cell responses including Th1 and Th2 determination. In this study we examined changes in co-stimulatory molecule expression and cytokine response of bovine macrophages exposed to salivary gland extracts (SGE) obtained from 2-3 day fed, pathogen-free adult <it>R. microplus</it>.</p> <p>Methods</p> <p>Peripheral blood-derived macrophages were treated for 1 hr with 1, 5, or 10 μg/mL of SGE followed by 1, 6, 24 hr of 1 μg/mL of lipopolysaccharide (LPS). Real-time PCR and cytokine ELISA were used to measure changes in co-stimulatory molecule expression and cytokine response.</p> <p>Results</p> <p>Changes were observed in co-stimulatory molecule expression of bovine macrophages in response to <it>R</it>. <it>microplus </it>SGE exposure. After 6 hrs, CD86, but not CD80, was preferentially up-regulated on bovine macrophages when treated with 1 μg/ml SGE and then LPS, but not SGE alone. At 24 hrs CD80, CD86, and CD69 expression was increased with LPS, but was inhibited by the addition of SGE. SGE also inhibited LPS induced upregulation of TNFα, IFNγ and IL-12 cytokines, but did not alter IL-4 or CD40 mRNA expression.</p> <p>Conclusions</p> <p>Molecules from the salivary glands of adult <it>R. microplus </it>showed bimodal concentration-, and time-dependent effects on differential up-regulation of CD86 in bovine macrophages activated by the TLR4-ligand, LPS. Up regulation of proinflammatory cytokines and IL-12, a Th1 promoting cytokine, were inhibited in a dose-dependent manner. The co-stimulatory molecules CD80, as well as the cell activation marker, CD69, were also suppressed in macrophages exposed to SGE. Continued investigation of the immunomodulatory factors will provide the knowledge base to research and develop therapeutic or prophylactic interventions targeting <it>R. microplus</it>-cattle interactions at the blood-feeding interface.</p

A broader role for AmyR in Aspergillus niger: regulation of the utilisation of d-glucose or d-galactose containing oligo- and polysaccharides

AmyR is commonly considered a regulator of starch degradation whose activity is induced by the presence of maltose, the disaccharide building block of starch. In this study, we demonstrate that the role of AmyR extends beyond starch degradation. Enzyme activity assays, genes expression analysis and growth profiling on d-glucose- and d-galactose-containing oligo- and polysaccharides showed that AmyR regulates the expression of some of the Aspergillus niger genes encoding α- and β-glucosidases, α- and β- galactosidases, as well as genes encoding α-amlyases and glucoamylases. In addition, we provide evidence that d-glucose or a metabolic product thereof may be the inducer of the AmyR system in A. niger and not maltose, as is commonly assumed

Predicting smear negative pulmonary tuberculosis with classification trees and logistic regression: a cross-sectional study

BACKGROUND: Smear negative pulmonary tuberculosis (SNPT) accounts for 30% of pulmonary tuberculosis cases reported yearly in Brazil. This study aimed to develop a prediction model for SNPT for outpatients in areas with scarce resources. METHODS: The study enrolled 551 patients with clinical-radiological suspicion of SNPT, in Rio de Janeiro, Brazil. The original data was divided into two equivalent samples for generation and validation of the prediction models. Symptoms, physical signs and chest X-rays were used for constructing logistic regression and classification and regression tree models. From the logistic regression, we generated a clinical and radiological prediction score. The area under the receiver operator characteristic curve, sensitivity, and specificity were used to evaluate the model's performance in both generation and validation samples. RESULTS: It was possible to generate predictive models for SNPT with sensitivity ranging from 64% to 71% and specificity ranging from 58% to 76%. CONCLUSION: The results suggest that those models might be useful as screening tools for estimating the risk of SNPT, optimizing the utilization of more expensive tests, and avoiding costs of unnecessary anti-tuberculosis treatment. Those models might be cost-effective tools in a health care network with hierarchical distribution of scarce resources

Mathematical Model of a Cell Size Checkpoint

How cells regulate their size from one generation to the next has remained an enigma for decades. Recently, a molecular mechanism that links cell size and cell cycle was proposed in fission yeast. This mechanism involves changes in the spatial cellular distribution of two proteins, Pom1 and Cdr2, as the cell grows. Pom1 inhibits Cdr2 while Cdr2 promotes the G2 → M transition. Cdr2 is localized in the middle cell region (midcell) whereas the concentration of Pom1 is highest at the cell tips and declines towards the midcell. In short cells, Pom1 efficiently inhibits Cdr2. However, as cells grow, the Pom1 concentration at midcell decreases such that Cdr2 becomes activated at some critical size. In this study, the chemistry of Pom1 and Cdr2 was modeled using a deterministic reaction-diffusion-convection system interacting with a deterministic model describing microtubule dynamics. Simulations mimicked experimental data from wild-type (WT) fission yeast growing at normal and reduced rates; they also mimicked the behavior of a Pom1 overexpression mutant and WT yeast exposed to a microtubule depolymerizing drug. A mechanism linking cell size and cell cycle, involving the downstream action of Cdr2 on Wee1 phosphorylation, is proposed

Mechanical Strain Regulates Osteoblast Proliferation through Integrin-Mediated ERK Activation

Mechanical strain plays a critical role in the proliferation, differentiation and maturation of bone cells. As mechanical receptor cells, osteoblasts perceive and respond to stress force, such as those associated with compression, strain and shear stress. However, the underlying molecular mechanisms of this process remain unclear. Using a four-point bending device, mouse MC3T3-E1 cells was exposed to mechanical tensile strain. Cell proliferation was determined to be most efficient when stimulated once a day by mechanical strain at a frequency of 0.5 Hz and intensities of 2500 µε with once a day, and a periodicity of 1 h/day for 3 days. The applied mechanical strain resulted in the altered expression of 1992 genes, 41 of which are involved in the mitogen-activated protein kinase (MAPK) signaling pathway. Activation of ERK by mechanical strain promoted cell proliferation and inactivation of ERK by PD98059 suppressed proliferation, confirming that ERK plays an important role in the response to mechanical strain. Furthermore, the membrane-associated receptors integrin β1 and integrin β5 were determined to regulate ERK activity and the proliferation of mechanical strain-treated MC3T3-E1 cells in opposite ways. The knockdown of integrin β1 led to the inhibition of ERK activity and cell proliferation, whereas the knockdown of integrin β5 led to the enhancement of both processes. This study proposes a novel mechanism by which mechanical strain regulates bone growth and remodeling