Senior Recital:Laura Doherty, Soprano

Kemp Recital Hall Saturday Afternoon March 22, 2003 5:00p.m

Mitochondrial DNA replication: a PrimPol perspective

PrimPol, (Primase-Polymerase), the most recently identified eukaryotic polymerase, has roles in both nuclear and mitochondrial DNA maintenance. PrimPol is able to act as a DNA polymerase, with the ability to extend primers and also bypass a variety of oxidative and photo-lesions. In addition, PrimPol also functions as a primase, catalysing the preferential formation of DNA primers in a zinc finger-dependent manner. Although PrimPol’s catalytic activities have been uncovered in vitro, we still know little about how and why it is targeted to the mitochondrion and what its key roles are in the maintenance of this multi-copy DNA molecule. Unlike nuclear DNA, the mammalian mitochondrial genome is circular and the organelle has a number of unique proteins essential for its maintenance, presenting a differing environment within which PrimPol must function. Here, we discuss what is currently known about the mechanisms of DNA replication in the mitochondrion, the proteins that carry out these processes and how PrimPol is likely to be involved in assisting this vital cellular process

Early visual detection of oriented line targets: spatial characteristics,and reference frames of early visual orientation-processing

The orientations of lines and edges are important in defining the structure of the visual environment, and observers can detect differences in line orientation within the first few hundred milliseconds of scene viewing. The present work is a psychophysical investigation of the mechanisms of early visual orientation-processing. In experiments with briefly presented displays of line elements, observers indicated whether all the elements were uniformly oriented or whether a uniquely oriented target was present among uniformly oriented nontargets. The minimum difference between nontarget and target orientations that was required for effective target-detection (the orientation increment threshold) varied little with the number of elements and their spatial density, but the percentage of correct responses in detection of a large orientation-difference increased with increasing element density. The differing variations with element density of thresholds and percent-correct scores may indicate the operation of more than one mechanism in early visual orientation-processIng. Reducing element length caused threshold to increase with increasing number of elements, showing that the effectiveness of rapid, spatially parallel orientation-processing depends on element length. Orientational anisotropy in line-target detection has been reported previously: a coarse periodic variation and some finer variations in orientation increment threshold with nontarget orientation have been found. In the present work, the prominence of the coarse variation in relation to finer variations decreased with increasing effective viewing duration, as if the operation of coarse orientation-processing mechanisms precedes the operation of finer ones. Orientational anisotropy was prominent even when observers lay horizontally and viewed displays by looking upwards through a black cylinder that excluded all possible visual references for orientation. So, gravitational and visual cues are not essential to the definition of an orientational reference frame for early vision, and such a reference can be well defined by retinocentric neural coding, awareness of body-axis orientation, or both

PrimPol is required for the maintenance of efficient nuclear and mitochondrial DNA replication in human cells

Eukaryotic Primase-Polymerase (PrimPol) is an enzyme that maintains efficient DNA duplication by repriming replication restart downstream of replicase stalling lesions and structures. To elucidate the cellular requirements for PrimPol in human cells, we generated PrimPol-deleted cell lines and show that it plays key roles in maintaining active replication in both the nucleus and mitochondrion, even in the absence of exogenous damage. Human cells lacking PrimPol exhibit delayed recovery after UV-C damage and increased mutation frequency, micronuclei and sister chromatin exchanges but are not sensitive to genotoxins. PrimPol is also required during mitochondrial replication, with PrimPol-deficient cells having increased mtDNA copy number but displaying a significant decrease in replication. Deletion of PrimPol in XPV cells, lacking functional polymerase Eta, causes an increase in DNA damage sensitivity and pronounced fork stalling after UV-C treatment. We show that, unlike canonical TLS polymerases, PrimPol is important for allowing active replication to proceed, even in the absence of exogenous damage, thus preventing the accumulation of excessive fork stalling and genetic mutations. Together, these findings highlight the importance of PrimPol for maintaining efficient DNA replication in unperturbed cells and its complementary roles, with Pol Eta, in damage tolerance in human cells

The expressiveness of mothers’ storybook reading in relation to children’s emerging language abilities in toddlerhood

PURPOSE: The quantity and quality of maternal language input in early childhood carry long-term implications for children's language development. This includes not only the quantity (e.g., total number of words) but also the quality of maternal language input (e.g., complexity and diversity of vocabulary and grammar use). One central qualitative aspect of maternal language use involves prosody. Prosody is a perceptually salient aspect of spoken language that conveys meaning, emphasis (i.e., via linguistic stress patterns), and emotion through changes in pitch (fundamental frequency (fo) modulation) and timing (rate, pausing). Prosody of a child’s main communication partner, often mothers, has been shown to play an important role in the language development of the child. There are numerous contexts in which language interactions can take place between a mother and child. Mother-child shared book reading (hereafter referred to as “shared reading”) is known to provide especially rich opportunities for language input and exposure, yet the contributions of oral reading expressiveness have yet to be specified. Initial evidence suggests that more expressive presentation of a storybook (through digital manipulation of fo mean) has a positive impact on children’s comprehension of the storybook text. Yet, it remains unclear whether maternal oral reading expressiveness is associated with children’s emerging language abilities in early childhood, particularly in toddlerhood, a critical developmental window for the early identification of late talkers. This work seeks to delineate the associations of maternal oral reading expressiveness on a child’s overall concurrent and subsequent language abilities. PROCEDURE: 44 mother-child dyads with children classified as either late talkers (n = 21) or typical controls (n=23) were selected from an ongoing larger longitudinal study of language delay in collaboration with researchers at Northwestern University. Maternal oral reading expressiveness during shared reading of the same children’s book was quantified through prosodic transcription and acoustic analysis in Praat yielding mean fundamental frequency (fo) and rate of speech as primary variables. Child language abilities were measured concurrently at the two-year time point and subsequently at the three-year time point using the Mullen Scales of Early Learning. Maternal socioeconomic status (SES) variables were assessed via family income-to-needs ratio and maternal education level. First, independent two sample t-tests were employed to determine whether late talker and typical control groups significantly differed in maternal oral reading expressiveness (as indicated by mean fo and speech rate) or SES. Thereafter, correlation analyses were employed to examine maternal oral reading expressiveness in relation to concurrent child language abilities at age two, and subsequent child language abilities at age three. Finally, multiple regression analyses were conducted to examine the extent to which maternal oral reading expressiveness may predict subsequent child language abilities approximately one year later (at age three) when controlling for SES. RESULTS: Preliminary findings revealed no group differences in measures of maternal oral reading expressiveness (i.e., mean fo, speech rate) between mothers of late talkers versus controls. However, at the whole-group level (among all dyads), correlational analyses revealed that maternal oral reading expressiveness (e.g., mean fo) is positively associated with child receptive and expressive language abilities at both two and three years. Furthermore, through a multiple regression model, maternal oral reading expressiveness was found to significantly contribute to the variance in child language abilities at both two years and longitudinally at three years when SES factors (i.e., parent education level, income-to-need ratio) were held constant. CONCLUSIONS: Preliminary results suggest that maternal oral reading expressiveness is significantly associated with children’s emerging language abilities in toddlerhood. These findings highlight the need for further investigation into the variable of maternal oral reading expressiveness as a possible modifiable environmental factor with the potential to facilitate positive language outcomes for children. Future and ongoing work will be necessary to obtain a more fine-grained characterization of variation in maternal oral reading expressiveness and examine maternal oral reading expressiveness in conjunction with other quantitative and qualitative indicators of maternal language input. Findings of this work carry implications for targeting reading expressiveness in parent-focused early intervention programs

PrimPol is required for replicative tolerance of G quadruplexes in vertebrate cells

G quadruplexes (G4s) can present potent blocks to DNA replication. Accurate and timely replication of G4s in vertebrates requires multiple specialized DNA helicases and polymerases to prevent genetic and epigenetic instability. Here we report that PrimPol, a recently described primase-polymerase (PrimPol), plays a crucial role in the bypass of leading strand G4 structures. While PrimPol is unable to directly replicate G4s, it can bind and reprime downstream of these structures. Disruption of either the catalytic activity or zinc-finger of PrimPol results in extreme G4-dependent epigenetic instability at the BU-1 locus in avian DT40 cells, indicative of extensive uncoupling of the replicative helicase and polymerase. Together, these observations implicate PrimPol in promoting restart of DNA synthesis downstream of, but closely coupled to, G4 replication impediments

Staff Training in Intellectual and Developmental Disability Settings: a Scoping Review

© 2019, Springer Science+Business Media, LLC, part of Springer Nature. Frontline staff are a valuable asset within an intellectual and developmental disability service. Their work dictates the overall standard of care delivered by the organization. However, there is evidence that the research relating to effective practice is having little impact on the competencies displayed by staff in the real-world setting. Therefore, a scoping review of published literature was conducted to investigate potential explanations for the inadequate dissemination of evidence-based practice in this sector. Systematic searches of relevant databases identified 156 papers for inclusion in the review. Practices in which staff were trained were categorized as either behavioral interventions or “other” interventions. The behavioral category was sub-divided into: a) assessment; b) antecedent; c) consequence and, d) “mixed” practices. Although the studies reviewed provided staff training across a range of practices, many empirically supported interventions were not utilized. Despite rigorous scientific support for strategies such as functional communication training and noncontingent reinforcement, the literature did not robustly evaluate effective protocols to disseminate these practices to frontline staff. The review also highlighted a continued reliance on individualized training packages, rather than the implementation of empirically supported training models. Finally, results showed that a relatively small number of included studies examined the impact of staff training on service user outcomes and adult service users were underrepresented across all intervention categories. Findings provide a potential explanation for the apparent disconnect between theoretical advancements and practice in the applied setting and are discussed in relation to approaches to staff training

Video Test to Evaluate Detection Performance of Drivers with Hemianopia: Preliminary Results

The ability of individuals with hemianopia to compensate for their vision impairment by eye/head scanning to detect hazards in their non-seeing (blind) hemifield varies widely in both simulator and on-road tests. Conventional visual fields tests do not reflect this variability, while simulator and on-road tests are time-consuming and expensive. We therefore developed a simple, 15-minute video-based pedestrian detection test suitable for implementation on a desktop computer and monitor. The test was found to be sensitive to detection deficits in both hemianopia and quadranopia, and predictive of detection performance in a driving simulator. Our preliminary findings suggest that the test provides a simple method of measuring detection ability relevant to driving which may be useful both as a screening test and as an evaluation tool for rehabilitation devices and training

PolDIP2 interacts with human PrimPol and enhances its DNA polymerase activities

Translesion synthesis (TLS) employs specialized DNA polymerases to bypass replication fork stalling lesions. PrimPol was recently identified as a TLS primase and polymerase involved in DNA damage tolerance. Here, we identify a novel PrimPol binding partner, PolDIP2, and describe how it regulates PrimPol's enzymatic activities. PolDIP2 stimulates the polymerase activity of PrimPol, enhancing both its capacity to bind DNA and the processivity of the catalytic domain. In addition, PolDIP2 stimulates both the efficiency and error-free bypass of 8-oxo-7,8-dihydrodeoxyguanosine (8-oxoG) lesions by PrimPol. We show that PolDIP2 binds to PrimPol's catalytic domain and identify potential binding sites. Finally, we demonstrate that depletion of PolDIP2 in human cells causes a decrease in replication fork rates, similar to that observed in PrimPol−/− cells. However, depletion of PolDIP2 in PrimPol−/− cells does not produce a further decrease in replication fork rates. Together, these findings establish that PolDIP2 can regulate the TLS polymerase and primer extension activities of PrimPol, further enhancing our understanding of the roles of PolDIP2 and PrimPol in eukaryotic DNA damage tolerance

Preferential Th1 Cytokine Profile of Phosphoantigen-Stimulated Human Vγ9Vδ2 T Cells

Human Vγ9Vδ2 T cells recognise pyrophosphate-based antigens (phosphoantigens) and have multiple functions in innate and adaptive immunity, including a unique ability to activate other cells of the immune system. We used flow cytometry and ELISA to define the early cytokine profiles of Vγ9Vδ2 T cells stimulated in vitro with isopentenyl pyrophosphate (IPP) and (E)-4-hydroxy-3-methyl-but-2 enyl pyrophosphate (HMB-PP) in the absence and presence of IL-2 and IL-15. We show that fresh Vγ9Vδ2 T cells produce interferon-γ (IFN-γ) and tumour necrosis factor-α (TNF-α) within 4 hours of stimulation with phosphoantigen, but neither IL-10, IL-13, nor IL-17 was detectable up to 72 hours under these conditions. Cytokine production was not influenced by expression or lack, thereof, of CD4 or CD8. Addition of IL-2 or IL-15 caused expansion of IFN-γ-producing Vγ9Vδ2 T cells, but did not enhance IFN-γ secretion after 24–72 hours. Thus, phosphoantigen-stimulated Vγ9Vδ2 T cells have potential as Th1-biasing adjuvants for immunotherapy