Bondjohansen0522
Understanding the gross organization of skeletal muscle is critical to understanding the mechanism of action of muscle physiology. Due to coronavirus disease-19 (COVID-19), many colleges have had to discontinue or curtail teaching and laboratory activities. CB-5083 in vivo Whether students are in the classroom or learning online, it is important for them to understand the basics of skeletal muscle organization that allows for movement. Manipulatives have been shown to enhance student learning and understanding in many fields, including physiology. This gives instructors an easy-to-follow tool for making a manipulative that allows students to see the organization of the skeletal muscle. Students can make this manipulative themselves from supplies commonly found in the home or office.Bacterial rod-shaped cells experiencing irreparable chromosome damage should filament without other morphological changes. Thymineless death (TLD) strikes thymidine auxotrophs denied external thymine/thymidine (T) supplementation. Such T-starved cells cannot produce the DNA precursor dTTP and therefore stop DNA replication. Stalled replication forks in T-starved cells were always assumed to experience mysterious chromosome lesions, but TLD was recently found to happen even without origin-dependent DNA replication, with the chromosome still remaining the main TLD target. T starvation also induces morphological changes, as if thymidine prevents cell envelope or cytoplasm problems that otherwise translate into chromosome damage. Here, we used transmission electron microscopy (TEM) to examine cytoplasm and envelope changes in T-starved Escherichia coli cells, using treatment with a DNA gyrase inhibitor as a control for "pure" chromosome death. Besides the expected cell filamentation in response to both treatments not in gyrase inhibitor-treated cells (negative control) that could be linked to subsequent irreparable chromosome damage. This is the first electron microscopy study of cells undergoing "genetic death" due to irreparable chromosome lesions.Clostridium perfringens causes necrotic enteritis (NE) in poultry. A chromosomal locus (VR-10B) was previously identified in NE-causing C. perfringens strains that encodes an adhesive pilus (NE pilus), along with a two-component system (TCS) designated here as PilRS. While the NE pilus is important in pathogenesis, the role of PilRS remains to be determined. The current study investigated the function of PilRS, as well as the Agr-like quorum-sensing (QS) system and VirSR TCS in the regulation of pilin production. Isogenic pilR, agrB, and virR null mutants were generated from the parent strain CP1 by insertional inactivation using the ClosTron system, along with the respective complemented strains. Immunoblotting analyses showed no detectable pilus production in the CP1pilR mutant, while production in its complement (CP1pilR+) was greater than wild-type levels. In contrast, pilus production in the agrB and virR mutants was comparable or higher than the wild type but reduced in their respective complemented strnvolved in adherence and NE development, along with a predicted two-component regulatory system (TCS), designated PilRS. In the present study, we have demonstrated the role of PilRS in regulating pilus production and collagen binding of C. perfringens. In addition, the Agr-like quorum sensing signaling pathway was found to be involved in the regulation. These findings have identified additional targets for developing nonantibiotic strategies to control NE disease.Bioinformatic analysis showed previously that a majority of promoters in the photoheterotrophic alphaproteobacterium Rhodobacter sphaeroides lack the thymine at the last position of the -10 element (-7T), a base that is very highly conserved in promoters in bacteria other than alphaproteobacteria. The absence of -7T was correlated with low promoter activity using purified R. sphaeroides RNA polymerase (RNAP), but the transcription factor CarD compensated by activating almost all promoters lacking -7T tested in vitro, including rRNA promoters. Here, we show that a previously uncharacterized R. sphaeroides promoter, the promoter for carD itself, has high basal activity relative to other tested R. sphaeroides promoters despite lacking -7T, and its activity is inhibited rather than activated by CarD. This high basal activity is dependent on a consensus-extended -10 element (TGn) and specific features in the spacer immediately upstream of the extended -10 element. CarD negatively autoregulates its own promoter by ter clearance. These findings support previous predictions that the effects of CarD on transcription can be either positive or negative, depending on the kinetic properties of the specific promoter.
Gestational lead (Pb) exposure can adversely affect offspring health through multiple mechanisms, including epigenomic alterations via DNA methylation (5mC) and hydroxymethylation (5hmC), an intermediate in oxidative demethylation. Most current methods do not distinguish between 5mC and 5hmC, limiting insights into their individual roles.
Our study sought to identify the association of trimester-specific (T1, T2, T3) prenatal Pb exposure with 5mC and 5hmC levels at multiple cytosine-phosphate-guanine sites within gene regions previously associated with prenatal Pb (
,
,
,
in whole blood leukocytes of children ages 11-18 years of age.
Participants from the Early Life Exposure in Mexico to Environmental Toxicants (ELEMENT) birth cohorts were selected (
n
=
144
) for pyrosequencing analysis following oxidative or standard sodium bisulfite treatment. This workflow directly quantifies total methylation (
5
mC
+
blood and that prenatal Pb exposure is associated with gene-specific 5mC and 5hmC levels at adolescence, providing evidence to consider 5hmC as a regulatory mechanism that is responsive to environmental exposures. https//doi.org/10.1289/EHP8507.
These findings suggest there is variable 5hmC in human whole blood and that prenatal Pb exposure is associated with gene-specific 5mC and 5hmC levels at adolescence, providing evidence to consider 5hmC as a regulatory mechanism that is responsive to environmental exposures. https//doi.org/10.1289/EHP8507.Ventilation and mechanics of breathing are an integral part of respiratory physiology that directly affect aerosol transport and deposition in the lung. Although natural breathing pattern varies widely among individuals, breathing pattern is controllable, and by using an appropriate breathing pattern, aerosol deposition can be substantially modified for desired purposes. Effects of breathing pattern have been investigated under carefully controlled inhalation conditions covering a wide range of tidal volumes (VT) and breathing frequencies (f) or respiratory times (T = 1/f). The studies have shown that lung deposition can increase or decrease as much as two times by changing the breathing pattern. Specific functional relationships have been found between lung deposition and breathing pattern parameters such that lung deposition can be estimated for any given breathing pattern. Both VT and T have shown strong effects on lung deposition, but their influence is variable depending on particle size, particularly, ultrafine vs. micron-sized particles. VT is more influential than T for micron-sized particles whereas VT and T are equally influential for ultrafine particles. Although effects of lung morphology are difficult to study systematically, comparison between normals and patients with obstructive airway disease has shown that lung deposition is closely related with the degree of airways obstruction and can be 2-3 times greater in patients with obstructive airway disease compared to normals. Thus, breathing pattern and the status of airways obstruction should be carefully considered in designing aerosol delivery and estimating deposition dose.Ultraviolet (UV) light has long been invoked as a source of energy for prebiotic chemical synthesis, but experimental support does not involve sources of UV light that look like the young Sun. Here we experimentally investigate whether the UV flux available on the surface of early Earth, given a favorable atmosphere, can facilitate a variety of prebiotic chemical syntheses. We construct a solar simulator for the UV light of the faint young Sun on the surface of early Earth, called StarLab. We then attempt a series of reactions testing different aspects of a prebiotic chemical scenario involving hydrogen cyanide (HCN), sulfites, and sulfides under the UV light of StarLab, including hypophosphite oxidation by UV light and hydrogen sulfide, photoreduction of HCN with bisulfite, the photoanomerization of α-thiocytidine, the production of a chemical precursor of a potentially prebiotic activating agent (nitroprusside), the photoreduction of thioanhydrouridine and thioanhydroadenosine, and the oxidation of ethanol isulfite.We report on the effect of intermolecular forces on the fluctuations of supported liquid films. Using an optically induced thermal gradient, we form nanometer-thin films of wetting liquids on glass substrates, where van der Waals forces are balanced by thermocapillary forces. We show that the fluctuation dynamics of the film interface is strongly modified by intermolecular forces at lower frequencies. Data spanning three frequency decades are in excellent agreement with theoretical predictions accounting for van der Waals forces. Our results emphasize the relevance of intermolecular forces on thermal fluctuations when fluids are confined at the nanoscale.Recently, higher-order topologies have been experimentally realized, featuring topological corner modes (TCMs) between adjacent topologically distinct domains. However, they have to comply with specific spatial symmetries of underlying lattices, hence their TCMs only emerge in very limited geometries, which significantly impedes generic applications. Here, we report a general scheme of inducing TCMs in arbitrary geometry based on Dirac vortices from aperiodic Kekulé modulations. The TCMs can now be constructed and experimentally observed in square and pentagonal domains incompatible with underlying triangular lattices. Such bound modes at arbitrary corners do not require their boundaries to run along particular lattice directions. Our scheme allows an arbitrary specification of numbers and positions of TCMs, which will be important for future on-chip topological circuits. Moreover, the general scheme developed here can be extended to other classical wave systems. Our findings reveal rich physics of aperiodic modulations, and advance applications of TCMs in realistic scenarios.Conventional control strategies for nitrogen-vacancy centers in quantum sensing are based on a two-level model of their triplet ground state. However, this approach fails in regimes of weak bias magnetic fields or strong microwave pulses, as we demonstrate. To overcome this limitation, we propose a novel control sequence that exploits all three levels by addressing a hidden Raman configuration with microwave pulses tuned to the zero-field transition. We report excellent performance in typical dynamical decoupling sequences, opening up the possibility for nano-NMR operation in low field environments.
