Structure and conservation of amyloid spines from the Candida albicans Als5 adhesin including similarity to human LARKS

Candida Als family adhesins mediate adhesion to biological and abiotic substrates, as well as fungal cell aggregation and fungal-bacterial co-aggregation. The activity of at least two family members, Als5 and Als1, is dependent on amyloid-like protein aggregation that is initiated by shear force. Each Als adhesin has a ~300-residue N-terminal Ig-like/invasin region. The following 108-residue, low complexity, threonine-rich (T) domain unfolds under shear to expose a critical amyloid-forming segment 322SNGIVIVATTRTV334 at the interface between the Ig-like/invasin domain 2 and the T domain of Candida albicans Als5. Amyloid prediction programs identified six potential amyloidogenic sequences in the Ig/invasin region and three others in the T domain of C. albicans Als5. Peptides derived from four of these sequences formed fibrils that bound thioflavin T, the amyloid indicator dye, and three of these revealed atomic-resolution structures of cross-b spines. These are the first atomic-level structures for fungal adhesins. One of these segments, from the T domain, revealed kinked b-sheets, similarly to LARKS (Low-complexity, Amyloid-like, Reversible, Kinked segments) found in human functional amyloids. Based on the cross-b structures in Als proteins, we use evolutionary arguments to identify functional amyloidogenic sequences in other fungal adhesins. Thus, cross-b structures are often involved in fungal pathogenesis and potentially in antifungal therapy.

A Facile Design of Colourimetric Polyurethane Nanofibrous Sensor Containing Natural Indicator Dye for Detecting Ammonia Vapour

Chemicals and industrial gases endanger both human health and the environment. The inhalation of colourless ammonia gas (NH3) can cause organ damage or even death in humans. Colourimetric materials are becoming more popular in the search for smart textiles for both fashion and specific occupational applications. Colourimetric textile sensors based on indicator dyes could be very useful for detecting strong gaseous conditions and monitoring gas leaks. In this study, black carrot extract (BCE) as a natural indicator dye and polyurethane (PU) polymer were used to develop a colourimetric sensor by electrospinning. The properties of the BCE/PU nanofibrous mats were characterized by the Fourier transform infrared spectrum (FTIR) and a scanning electron microscope (SEM). The BCE caused a change in the morphology of the PU nanofibrous mat. To evaluate the colour shift due to NH3 vapour, the BCE/PU nanofibrous mats were photographed by a camera, and software was used to obtain the quantitative colour data (CIE L*a*b). The BCE/PU nanofibrous exhibited a remarkable colour change from pink–red to green–blue under NH3 vapour conditions with a fast response time (≤30 s). These findings showed that colourimetric nanofibrous textile sensors could be a promising in situ material in protective clothing that changes colour when exposed to harmful gases.

Flow cytometric approach to evaluate the impact of hydro-technical concrete compounds’ release to the freshwater microbiome

The aim of this research was to test the potential of applying a flow cytometric procedure to evaluate the impact of concrete compounds’ release to the freshwater microbiome. Cells from the collected samples were stained with a fluorogenic redox indicator dye that measures the redox potential of microbial cells. This novel approach was combined with the assessment of microorganisms’ penetration into the internal structures of concrete using the Rose Bengal sodium salt staining. Rose Bengal staining revealed an intense fouling of the upper and side walls of the concrete cubes and also indicated the penetration of microorganisms inside the concrete as observed for the cubes’ cross-sections. Flow cytometric cellular redox potential measurement revealed high percentages of active cells within the concrete’s porous structures and in non-exposed water (32.7% and 30.2% of active cells) versus samples from exposed water and concrete’s outer surfaces (6.8%, 6.1%, and 3.3% of active cells). The results demonstrated a detrimental impact of hydro-technical concrete on the vitality of microbial cells within the freshwater environment. Tested protocol by analyzing the physiology of microbial cells improved the functional description of complex communities to evaluate the fate of contaminants present in the concrete-based hydro-technical infrastructure.

Cortical spheroids display oscillatory network dynamics

Three-dimensional brain cultures can facilitate the study of central nervous system function and disease, and one of the most important components that they present is neuronal activity on a network level. Here we demonstrate network activity in rodent cortical spheroids while maintaining the networks intact in their 3D state. Networks developed by nine days in culture and became more complex over time. To measure network activity, we imaged neurons in rat and mouse spheroids labelled with a calcium indicator dye, and in mouse spheroids expressing GCaMP. Network activity was evident when we electrically stimulated spheroids, was abolished with glutamatergic blockade, and was altered by GABAergic blockade or partial glutamatergic blockade. We quantified correlations and distances between somas with micron-scale spatial resolution. Spheroids seeded at as few as 4,000 cells gave rise to emergent network events, including oscillations. These results are the first demonstration that self-assembled rat and mouse spheroids exhibit network activity consistent with in vivo network events. These results open the door to experiments on neuronal networks that require fewer animals and enable high throughput experiments on network-perturbing alterations in neurons and glia.

The calcitonin receptor regulates osteocyte lacunae acidity during lactation in mice

The physiological role of calcitonin, and its receptor, the CTR (or Calcr), has long been debated. We previously provided the first evidence for a physiological role of the CTR to limit maternal bone loss during lactation in mice by a direct action on osteocytes to inhibit osteocytic osteolysis. We now extend these findings to show that CTR gene expression is upregulated two- to three-fold in whole bone of control mice at the end of pregnancy (E18) and lactation (P21) compared to virgin controls. This was associated with an increase in osteoclast activity evidenced by increases in osteoclast surface/bone surface and Dcstamp gene expression. To investigate the mechanism by which the CTR inhibits osteocytic osteolysis, in vivo acidification of the osteocyte lacunae during lactation (P14 days) was assessed using a pH indicator dye. A lower pH was observed in the osteocyte lacunae of lactating Global-CTRKOs compared to controls and was associated with an increase in the gene expression of ATPase H+ transporting V0 subunit D2 (Atp6v0d2) in whole bone of Global-CTRKOs at the end of lacation (P21). To determine whether the CTR is required for the replacement of mineral within the lacunae post-lactation, lacunar area was determined 3 weeks post-weaning. Comparison of the largest 20% of lacunae by area did not differ between Global-CTRKOs and controls post-lactation. These results provide evidence for CTR activation to inhibit osteocytic osteolysis during lactation being mediated by regulating the acidity of the lacunae microenvironment, whilst the CTR is dispensable for replacement of bone mineral within lacunae by osteocytes post-lactation.

Comparison of Two Different Semiquantitative Urinary Dipstick Tests with Albumin-to-Creatinine Ratio for Screening and Classification of Albuminuria According to KDIGO. A Diagnostic Test Study

Background: Semiquantitative dipstick tests are utilized for albuminuria screening. Methods: In a prospective cross-sectional survey, we analyzed the diagnostic test validity of the semiquantitative colorimetric indicator-dye-based Combur9-Test® and the albumin-specific immunochromatographic assay Micral-Test® for the detection of albuminuria, the distribution of the semiquantitative measurements within the albuminuria stages according to KDIGO, and the utility for albuminuria screening compared with an albumin-to-creatinine ratio (ACR) in a walk-in population. Results: In 970 subjects, albuminuria (≥30 mg/g) was detected in 12.7% (95% CI 85.6–96.3%) with the ACR. Sensitivity was 82.9% (95% CI 75.1–89.1%) and 91.9% (95% CI 88.7–96.9%) and specificity 71.5% (95% CI 68.4–74.6%) and 17.5% (95% CI 15.0–20.2%) for the Combur9-Test® and Micral-Test®, respectively. Correct classification to KDIGO albuminuria stages A2/A3 with the Combur9-Test® was 15.4%, 51.4%, and 87.9% at cut-offs of 30, 100, and ≥300 mg/dL, and with the Micral-Test® it was 1.8%, 10.5%, and 53.6% at cut-offs of 2, 5, and 10 mg/dL, respectively. Overall, disagreement to KDIGO albuminuria was seen in 27% and 73% with the Combur9-Test® and Micral-Test®, respectively. From the total population, 62.5% and 15.3% were correctly ruled out and 2.2% and 1% were missed as false-negatives by the Combur9-Test® and Micral-Test®, respectively. Conclusion: Compared to the Combur9-Test®, the utility of the Micral-Test® is limited, because the fraction of correctly ruled out patients is small and a large proportion with a positive Micral-Test® require a subsequent ACR conformation test.

From Colour Catcher® to colorimetric sensors: disposable and cheap devices for inorganic ions determination

We describe disposable and cheap colorimetric devices obtained by fixing classical dyes on the commercial paper sheet known as "Colour Catcher®" (here named under the acronym CC), the product used to prevent color runs in washing machines cycles. These devices can be used as colorimetric sensors for different analytes of environmental and biological interest since the indicator dye, fixed on the solid material, changes its spectral properties (color and hence UV-vis spectrum) upon contact with the analyte. The relationship between the analyte content and the UV-vis spectrum (or RGB values) change of each sensor is provided using a chemometric tool: the Partial Least Squares regression (PLS). Promising results were obtained when applying these sensors to actual samples, so because of their simple preparation with low-cost reagents, they can be effective for application in environmental and food analysis.

Estudo do Espectro de Absorção do Vermelho de Metila.

Methyl red or known as methyl red, also called C.I.Acid Red 2, C.I. 13020, is a Ph indicator dye that turns red in acidic solutions. It is an azo dye and appears as a dark red crystalline powder. Its molecular formula is C15H15N3O2, which has a molar mass of 269,299 g / mol and a melting point of 179-182oC. The objective of this work is to verify the molecular geometry, and the electronic absorption behavior of this compound, mainly how it behaves in the state of water, acetone, ethanol and methanol. The methodology used is the calculation of the absorption spectrum in the visible ultraviolet range, used in the DFT method with the functional B3LYP and in the 6-311 + G (d, p). Also used on the Hirsfeld surface, seeing the behavior of electronic density in the strong and weak nuclear bonds that occur at the points of hydrogen and oxygen bonds. With this study of the absorption and surface properties of Hirsfeld, we can see how its electronic state behaves, leading to an understanding of how methyl red can be a good indicator of pH count.

Exogenous reproductive hormones nor Candida albicans colonization alter the near neutral mouse vaginal pH

While human vaginal pH in childbearing aged women is conclusively acidic, the mouse vaginal pH is reported as being near neutral. However, this information appears to be somewhat anecdotal with respect to vulvovaginal candidiasis as such claims in the literature frequently lack citations of studies that specifically address this physiological factor. Given the disparate pH between mice and humans, the role of exogenous hormones and colonization by the fungal pathogen Candida albicans in shaping vaginal pH was assessed. Use of a convenient modified vaginal lavage technique with the pH indicator dye phenol red demonstrated that indeed vaginal pH was near neutral (7.2 ± 0.24) and was not altered by delivery of progesterone or estrogen in C57BL/6 mice. These trends were conserved in DBA/2 and CD-1 mouse backgrounds commonly used in the mouse model of vaginitis. It was also determined that vaginal colonization with C. albicans did not alter the globally neutral vaginal pH over the course of one week. Construction and validation of a C. albicans reporter strain expressing GFPy driven by the pH-responsive PHR1 promoter confirmed that the murine vaginal pH to be at least ≥ 6.0. Collectively, our data convincingly demonstrate a stable and conserved near neutrality of the mouse vaginal pH during vulvovaginal candidiasis and should serve as a definitive source for future reference. Implications and rationale for disparate pH in this model system are also discussed.

Possible use of tetrabromophenolphthalein ethyl ester as a liquid dosimeter

Aqueous solution of pH indicator dye tetrabromophenolphthalein ethyl ester containing chloral hydrate was studied for its possibility to be used as a liquid dosimeter. The useful measuring range was found to be (0.5–2 kGy) depending on the concentration of both dye and chloral hydrate added. The system has good stability before and after irradiation under different storage conditions. A comparison study between direct irradiation of the dye containing chloral hydrate and indirect method that executed through avoiding exposure of the dye to irradiation and irradiate the chloral hydrate only followed by outputs for interaction with dye was investigated seeking to extend the dose range up to 5 kGy.