A new technique for staining mast cells using ferroin

We describe here a new method for specific staining of mast cells using ferroin. Different hamster tissues were fixed in 4% formalin and processed for paraffin embedding. Sections were stained with hematoxylin followed by ferroin acidified with 2.5 N sulfuric acid to pH 4.0. Mast cells stained an intense orange color that contrasted markedly with bluish violet nuclei. High contrast was also observed when ferroin colored sections were counterstained with light green instead of hematoxylin. To evaluate the specificity of the stain, hamster cheek pouch sections were stained with toluidine blue, alcian blue-safranin O, and ferroin. Quantitative evaluation of mast cells stained with the three techniques showed no statistical difference. The simplicity and selectivity of this method is sufficient for image analysis of mast cells.     

Caenorhabditis elegans body mechanics are regulated by body wall muscle tone

Body mechanics in the nematode Caenorhabditis elegans are central to both mechanosensation and locomotion. Previous work revealed that the mechanics of the outer shell, rather than internal hydrostatic pressure, dominates stiffness. This shell is comprised of the cuticle and the body wall muscles, either of which could contribute to the body mechanics. Here, we tested the hypothesis that the muscles are an important contributor by modulating muscle tone using optogenetic and pharmacological tools, and measuring animal stiffness using piezoresistive microcantilevers. As a proxy for muscle tone, we measured changes in animal length under the same treatments. We found that treatments that induce muscle contraction generally resulted in body shortening and stiffening. Conversely, methods to relax the muscles more modestly increased length and decreased stiffness. The results support the idea that body wall muscle activation contributes significantly to and can modulate C. elegans body mechanics. Modulation of body stiffness would enable nematodes to tune locomotion or swimming gaits and may have implications in touch sensation.     

Testing the Effects of Biogenic Amines and Alternative Topical Solvent Types on the Behavioral Repertoire of Two Web‐Building Spiders

Investigating the proximate mechanism underlying behavior has long been a primary goal of ethologists. With the recent focus on behavioral correlations (e.g., behavioral syndromes), a fundamental question arises regarding what mechanisms may drive positive relationships between functionally distinct behaviors. Understanding these mechanisms can inform critical questions, such as why distinct behaviors are often correlated, and can also lend insights into how behavioral similarities are conserved across species. Arthropods provide an idea system to study these questions as the biogenic amines, such as octopamine and serotonin, have long been known to mediate a large number of behaviors such as aggression, dominance, escape behavior, and others. Behaviorists have several ways in which they can manipulate these biogenic amines in vivo, including injection, feeding, and topical application. Topical application is potentially an optimal method for manipulating amine concentrations, given that it is minimally invasive and relatively precise. Here, we investigate the role of biogenic amines, octopamine, and serotonin, in mediating a range of similar and often correlated behaviors in two distantly related species of spiders, the western black widow, Latrodectus hesperus, and the funnel‐web spider, Agelenopsis pennsylvanica. Additionally, we investigate the behavioral effects associated with three commonly used carrier solvents: dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and acetone. We demonstrate that biogenic amines are involved both in mediating several behaviors, and also potentially the links between different behaviors. We also show that the same behaviors in different species are not affected by biogenic amines in the same manner, suggesting differences in the underlying neurophysiological mechanisms governing behavior. Furthermore, we discovered large and pervasive effects associated with both carrier solvents, thus calling into question the potential usefulness and interpretability of topical application methods in behavioral research.     

Determination of strain energy function for arterial elastin: Experiments using histology and mechanical tests

The long-range reversible deformation of vertebrate arteries is primarily mediated by elastin networks that endure several million deformation cycles without appreciable fatigue. To determine how elastin contributes to the composite arterial properties, we studied the three-dimensional microstructure and biomechanics of isolated elastin. We initially estimated the sensitivity of these studies by comparing two elastin isolation protocols, autoclaving and alkali-extraction, and measured their effect on isolated elastin using uniaxial tests and histology. These studies show that autoclaved tissues have a trend for higher modulus (900.79+/-678.02 kPa) than alkali-extracted samples (417.74+/-162.23 kPa)albeit with higher collagen-proteoglycan impurities, and (2) greater optical density (78.6+/-9.1%) than alkali-extracted groups (46.2+/-5.9%), suggesting that autoclaving is superior to alkali-extraction for biomechanical tests on elastin. Using these data we show that an isotopic Mooney-Rivlin model cannot adequately represent arterial elastin. The neo-Hookean model, with coefficient 162.57 (+/-115.44) kPa for autoclaved and 76.94 (+/-27.76) kPa for alkali-extracted samples, fits the uniaxial data better. Autoclaved elastins also show linear stress-strain response and equal stiffness in circumferential and axial directions suggesting equal number of layers in these directions and that elastin may help distribute tensile stresses during vessel inflation. Histology of autoclaved and control porcine arteries reveals axial elastin fibers in intimal and adventitial layers but circumferential medial fibers. We propose an orthotropic material symmetry for arterial elastin with two orthogonally oriented and symmetrically placed mechanically equivalent fibers. An exact form of the constitutive equation will be obtained in a future study.     

Hes1 Increases the Invasion Ability of Colorectal Cancer Cells via the STAT3-MMP14 Pathway

The Notch pathway contributes to self-renewal of tumor-initiating cell and inhibition of normal colonic epithelial cell differentiation. Deregulated expression of Notch1 and Jagged1 is observed in colorectal cancer. Hairy/enhancer of split (HES) family, the most characterized targets of Notch, involved in the development of many cancers. In this study, we explored the role of Hes1 in the tumorigenesis of colorectal cancer. Knocking down Hes1 induced CRC cell senescence and decreased the invasion ability, whereas over-expression of Hes1 increased STAT3 phosphorylation activity and up-regulated MMP14 protein level. We further explored the expression of Hes1 in human colorectal cancer and found high Hes1 mRNA expression is associated with poor prognosis in CRC patients. These findings suggest that Hes1 regulates the invasion ability through the STAT3-MMP14 pathway in CRC cells and high Hes1 expression is a predictor of poor prognosis of CRC.