Dually-mode-locked ND: YAG laser

Mode-locking is stabilized effectively by conventional loss-modulator and phase-modulator, mode-locking elements placed in laser cavity in optical series with one another. Resulting dually-mode-locked system provides pulses with constant phase relative to mode-lock drive signal without presence of relaxation oscillation noise

Dog-friendly design: Exploring materials and finishes as they relate to dog ownership

The purpose of this study is to investigate materials and finishes in residential homes which are often damaged by dogs and to correlate these damaging behaviors to other factors. This information was gathered through a two-fold approach. First, a comprehensive review of literature regarding household furnishings and finishes and a sensory and behavioral analysis of dogs is performed. The research includes properties and characteristics of finishes and furnishings commonly used in residential households. The behavioral analysis conducted analyzes the factors that contribute to destructive behavior in dogs. An analysis of dogs\u27 sensory systems and how they impact the way they perceive the world concluded the review of literature. The second method of data collection performed for this study is a survey of current dog owners. This survey obtains information regarding three areas of dog ownership. The first category gains information pertaining to participant housing status, geographical location and the number of dogs in the household. The second area obtains information about the household dog(s). Dog breed, amount of shedding, and where the dog was obtained are the areas covered within this section. The final portion of the survey asks participants to respond to questions regarding damaging behavior, what items were damaged, time dogs spent home alone, how they spend their time home alone, daily exercise for the dog and general grooming habits. For households with more than one dog, participants were asked to answer the questions about one dog at a time. Once the survey information was obtained, the data is analyzed, compared and contrasted to a number of factors. Once patterns and correlations have been identified, the final discussion makes recommendations based on the anecdotal evidence provided by dog owners and the evidence-based research found in the review of literature

rRNA Promoters as Targets for Transcription Factors: Structural and Functional Studies of PhERI and CarD

Transcription, the process of copying information encoded in DNA into RNA, to facilitate the expression of encoded proteins, is a central process in all living organisms. The expression and repression of subsets of genes allows different cell types in an organism to maintain diverse physiological roles and permits individual cells to respond to various environmental stimuli. Transcription in prokaryotic cells is performed by a single macromolecular complex, RNA polymerase. In rapidly growing cells with abundant resources, prokaryotic RNA polymerase is mostly located at ribosomal RNA (rRNA) promoters, actively transcribing the large, structured RNAs required for protein translation. As resources become more scarce, RNA polymerase directly responds to cellular signals that lead to the repression of rRNA transcription. This regulation has long been thought to be driven primarily by small molecule effectors that signal scarcity. In this thesis, I will report work done on two transcription factors in prokaryotes that regulate RNA polymerase activity at rRNA promoters. The Staphylococcus aureus (Sau) Phage G1 protein PhERI (previously ORF67), was previously described as a general RNA polymerase inhibitor. PhERI expression in Sau cells inhibits cell growth, which could have therapeutic potential against this deadly pathogen. I describe the structure of PhERI bound to Sau σ A 4, the region of RNA polymerase to which it binds. While PhERI interacts with RNAP through σ, I show that RNA polymerase activity at most -10/-35 promoters is not affected. Structural, biochemical and genomic approaches demonstrate that PhERI interacts with σA 4 near the -35 element of all promoters, but blocks the binding of an additional RNA polymerase subunit, the α-CTD, to UP-element DNA sequences. PhERI therefore only inhibits RNA polymerase activity at promoters requiring UP-element activation, most notably the rRNA promoters. This work not only delineates the mechanism of PhERI but also describes novel -10/-35 promoters in Staphlococcus aureus, defines rRNA promoters in this organism for the first time, and shows UP-element activation is required for rRNA transcription. The mycobacterial protein CarD is known to interact with RNA polymerase, but its impact on transcription directly at promoters has not been described. The structure of the Thermus Thermophilus CarD was solved in the lab, allowing a model for the interaction between CarD and RNA polymerase to be built. I show that CarD stimulates RNA polymerase activity at rRNA promoters, but not all promoters, by directly stabilizing the RNA polymerase open complex on promoter DNA. These two proteins both exploit unique parameters of RNA polymerase at rRNA promoters to specifically regulate RNA polymerase activity at these functionally important promoters

Identification of an immunogenic Mannheimia haemolytica immunoglobulin-, fibronectin- and fibrinogen-binding protein differentially expressed in vitro

Bovine respiratory disease (BRD), or shipping fever , is the cause of large losses to the cattle industry annually and is primarily caused by Mannheimia haemolytica serotype (ST) 1. M. haemolytica, a normal flora respiratory tract bacterium, rapidly multiplies upon a stressful occurrence and colonizes the lower respiratory tract. This can lead to fibrinohemorrhagic pneumonia. Bacterial immunoglobulin-binding protein (IgBP) expression is known to play a role in the pathogenesis of a variety of organisms. Far-Western blot demonstrated the presence of an IgBP(s) in whole cell sonicates (WCSs) and a culture supernatant (CS) preparation from M. haemolytica ST 1. The IgBP(s) was isolated by affinity chromatography and used in a far-Western blot to show that the IgBP(s) also bound the extra-cellular matrix proteins (ECMPs) fibrinogen and fibronectin. ECMPs are known to play a role in colonization of some bacteria by acting as a bridge enabling binding between bacteria expressing extracellular matrix-binding proteins and epithelial cells. Flow cytometry showed the surface expression of an IgBP(s) on whole cell M. haemolytica. Immune sera from convalescent cattle showed an increased antibody response by Western blot to the 75.0 kDa IgBP when compared to sera from naive or acutely infected cattle. It was demonstrated that all 12 serotypes (1, 2, 5--9, 12--14, and 16) bound both bovine Fc IgG and sheep Fc IgG. Significant differences were not found between ST1, most frequently isolated in infections in cattle and ST2, isolated predominantly in sheep mannheimiosis. The effect of various M. haemolytica growth conditions on IgBP(s) expression was assessed by 2-D gel electrophoresis analysis. Membrane expression of M. haemolytica IgBP(s) was increased a minimum of two fold when M. haemolytica was grown in RPMI-1640 with 10%FBS, RPMI-1640 at 40°C and RPMI-1640 with 50 muM 2,2\u27-dipyridyl when compared to growth in RPMI-1640 at 37°C. The IgBP(s) constituted up to 19.9% of M. haemolytica membrane proteins when M. haemolytica was grown in RPMI at 40°C. This study shows a possible role in virulence for the M. haemolytica IgBP(s). It may enable M. haemolytica to evade the host immune response and may play a role in colonization through binding fibronectin or fibrinogen

Relax and Recharge Club

An afterschool club that focuses on providing calming and stress relieving activities that also help them build healthy coping mechanisms to stress at a young age

Relax and Recharge Club

An afterschool club that focuses on providing calming and stress relieving activities that also help them build healthy coping mechanisms to stress at a young age

Pif1-family helicases cooperatively suppress widespread replication-fork arrest at tRNA genes

Saccharomyces cerevisiae encodes two distinct Pif1-family helicases – Pif1 and Rrm3 – which have been reported to play distinct roles in numerous nuclear processes. Here, we systematically characterize the roles of Pif1 helicases in replisome progression and lagging-strand synthesis in S. cerevisiae. We demonstrate that either Pif1 or Rrm3 redundantly stimulate strand-displacement by DNA polymerase δ during lagging-strand synthesis. By analyzing replisome mobility in pif1 and rrm3 mutants, we show that Rrm3, with a partially redundant contribution from Pif1, suppresses widespread terminal arrest of the replisome at tRNA genes. Although both head-on and codirectional collisions induce replication fork arrest at tRNA genes, head-on collisions arrest a higher proportion of replisomes. Consistent with this observation, we find that head-on collisions between tRNA transcription and replication are under-represented in the S. cerevisiae genome. We demonstrate that tRNA-mediated arrest is R-loop independent, and propose that replisome arrest and DNA damage are mechanistically separable