AFTER THE NIXON RESIGNATION WE STILL NEED REFORM!

Agricultural and Food Policy,

AGRICULTURE IN THE NATION'S POLITICS

Political Economy,

FARM POLITICS AND THE SEPARATION OF POWERS

Agricultural and Food Policy,

19F NMR studies of the solution structure and dynamics of 5-fluorouracil-substituted valine tRNA from Escherichia coli

Valine tRNA was purified from 5-fluorouracil (FUra) treated E. coli cells and resolved into two isoaccepting species, termed FUra tRNA(,1)(\u27Val) forms (A) and (B), respectively. The (\u2719)F NMR spectrum of the (B) form contains 13 resolved resonances for the 14 incorporated FUra residues dispersed from 1.6 and 8.5 ppm (FUra = 0 ppm). (\u2719)F NMR spectra of the (A) and (B) forms differ in the shift of peak E from ca. 4.3 ppm in form (B) upfield to ca. -15 ppm in form (A). In light of previous sequence studies with FUra tRNA(,F)(\u27Met) and (\u2719)F spectral differences between the two forms of tRNA(,1)(\u27Val), peak E in the NMR spectrum of FUra tRNA(,1)(\u27Val) (B) is assigned to F17. (\u2719)F NMR thermal denaturation, bisulfite modification, pH dependence, and Solvent Isotope Shift studies indicate that downfield NMR peaks (4.8-8.5 ppm) correspond to residues participating in tertiary structure interactions, upfield peaks (1.6-3.8 ppm) correspond to residues located in helical domains, and central-field resonances (3.9-4.5 ppm) correspond to residues in relatively unstructured environments. Thermal denaturation studies allow assignment of peak B in the (\u2719)F NMR spectrum of FUra tRNA(,1)(\u27Val) to F54 and, based on this assignment, demonstrate a thermally-induced low temperature (T(,m) = 36(DEGREES)C) structural transition to a less stacked conformation in the T(psi)C-loop region of the tRNA. Based on a conserved ca. 4 ppm upfield shift of peak A in the (\u2719)F NMR spectra of FUra tRNA(,1)(\u27Val), tRNA(,f)(\u27Met), and tRNA(,m)(\u27Met) upon removal of Mg(\u272+), peak A has been tentatively assigned to F55. (\u2719)F (\u2719)F nuclear Overhauser effect studies with 6-deutero-FUra tRNA(,1)(\u27Val) agree with and enhance the assignment of peaks A and B to F55 and F54, respectively.;(\u2719)F NMR relaxation parameters were measured and interpreted within the diffusion in a cone or two-state jump formalisms in order to derive motional amplitudes, due to pseudorotational fluctuations of the ribose ring, for the individual 5-fluorouridine (FUrd) residues in FUra tRNA(,1)(\u27Val). These motions occur on the nanosecond time scale and the amplitudes may be correlated directly with the environmental domain of the residue. The large chemical shift anisotropy contributions to the (\u2719)F linewidths indicate a maintenance of hydrogen-bonding and/or stacking interactions for all FUrd residues in FUra tRNA(,1)(\u27Val). A correlation between residue mobility and solvent exposure is also demonstrated

Monovalent cation induced structural transitions in telomeric DNAs: G-DNA folding intermediates

Telomeric DNA consists of G- and C-rich strands that are always polarized such that the G-rich strand extends past the 3’ end of the duplex to form a 12-16-base overhang. These overhanging strands can self-associate in vitro to form intramolecular structures that have several unusual physical properties and at least one common feature, the presence of non-Watson-Crick G-G base pairs. The term “G-DNA” was coined for this class of structures (Cech, 1988). On the basis of gel electrophoresis, imino proton NMR, and circular dichroism (CD) results, we find that changing the counterions from sodium to potassium (in 20 mM phosphate buffers) specifically induces conformational transitions in the G-rich telomeric DNA from Tetrahymena, d(T2G4)4 (TET4), which results in a change from the intramolecular species to an apparent multistranded structure, accompanied by an increase in the melting temperature of the base pairs of \u3e 2 5 O , as monitored by loss of the imino proton NMR signals. NMR semiselective spin-lattice relaxation rate measurements and HPLC size-exclusion chromatography studies show that in 20 mM potassium phosphate (pH 7) buffer (KP) TET4 is approximately twice the length of the form obtained in 20 mM sodium phosphate (pH 7) buffer (Nap) and that mixtures of Na+ and K+ produce mixtures of the two forms whose populations depend on the ratio of the cations. Since K+ and NH4+ are known to stabilize a parallel-stranded quadruplex structure of poly[r(I),], we infer that the multistranded structure is a quadruplex. Our results indicate that specific differences in ionic interactions can result in a switch in telomeric DNAs between intramolecular hairpin-like or quadruplex-containing species and intermolecular quadruplex structures, all of which involve G G base pairing interactions. We propose a model in which duplex or hairpin forms of G-DNA are folding intermediates in the formation of either 1-, 2-, or 4-stranded quadruplex structures. In this model monovalent cations stabilize the duplex and quadruplex forms via two distinct mechanisms, counterion condensation and octahedral coordination to the carbonyl groups in stacked planar guanine “quartet” base assemblies. Substituting one of the guanosine residues in each of the repeats of the Tetrahymena sequence to give the human telomeric DNA, d(T2AG,)4, results in less effective K+-dependent stabilization. Thus, the ion-dependent stabilization is attenuated by altering the sequence. Upon addition of the Watson-Crick (WC) complementary strand, only the Na+-stabilized structure dissociates quickly to form a WC double helix. This demonstrates that under some circumstances the K+-stabilized G-DNA structure can be kinetically preferred over WC DNA

Assessment of commercially available computerized neurocognitive testing in the adolescent concussed athlete: A retrospective analysis.

Background: Clinicians frequently use computer-based neurocognitive assessments to aid in the diagnosis and management of Sport Related Concussion (SRC). With practitioners using varied Neuro-Cognitive Assessment Tools (NCAT), questions arise concerning among NCAT and how these differences may affect patient care. The purpose of the current study is to offer a comparative analysis of two widely accepted, commercially available computer-based neurocognitive testing modalities in the adolescent concussed athlete. Hypothesis: There will be a difference between the C3 Logix® vs ImPACT® scoring in the IRPT and RTP Study Design: Retrospective chart review. Methods: In order to identify patients that were diagnosed with SRC, the records of patients reporting to a Sports Medicine practice were reviewed from a period of 18 months. All patients were assessed with either the ImPACT® or C3 Logix NCAT®. The date of the injury (DOI) as well as the patient’s symptom level (IVAL), time to initiation of the return to play protocol (IRTP), and time to the return to play (RTP) were recorded. Results: Two hundred and twenty-two records (222) were identified. There was no difference in the symptom score (P = 0.22) at the IEVAL between C3 Logix® (31.5±27.0) and ImPACT® (23.2±21.9), in the IRTP (P = 0.22) between the C3 Logix® (6.2±4.3 days) and ImPACT® (5.1±4.3 days) or RTP (P = 0.46) between C3 Logix (12.1±4.9 days) and ImPACT (15.6±19.8 days). Weak to moderate correlations were found between symptom scores, IRTP, and RTP. Conclusions: Clinicians made similar recommendations, independent of the NCAT used, as when to initiate the return to play protocol and when the patient could ultimately return to play. Clinical Relevance: The particular NCAT utilized by clinician was not a primary factor in the clinical judgement towards the management of the patient with SRC

Modality-Independent Effects of Phonological Neighborhood Structure on Initial L2 Sign Language Learning

The goal of the present study was to characterize how neighborhood structure in sign language influences lexical sign acquisition in order to extend our understanding of how the lexicon influences lexical acquisition in both sign and spoken languages. A referent-matching lexical sign learning paradigm was administered to a group of 29 hearing sign language learners in order to create a sign lexicon. The lexicon was constructed based on exposures to signs that resided in either sparse or dense handshape and location neighborhoods. The results of the current study indicated that during the creation of the lexicon signs that resided in sparse neighborhoods were learned better than signs that resided in dense neighborhoods. This pattern of results is similar to what is seen in child first language acquisition of spoken language. Therefore, despite differences in child first language and adult second language acquisition, these results contribute to a growing body of literature that implicates the phonological features that structure of the lexicon is influential in initial stages of lexical acquisition for both spoken and sign languages. This is the first study that uses an innovated lexicon-construction methodology to explore interactions between phonology and the lexicon in L2 acquisition of sign language

Specific Interaction of Glyceraldehyde 3-Phosphate Dehydrogenase with the 5′-Nontranslated RNA of Hepatitis A Virus

Initiation of translation of hepatitis A virus (HAV) RNA occurs by internal entry and is likely to involve the interaction of trans-acting cellular protein factors with cis-acting structural elements of an internal ribosomal entry segment (IRES) within the 5'-nontranslated RNA. To characterize interactions between African green monkey kidney (BS-C-1) cell proteins and the predicted stem-loop IIIa (nucleotides 155-235) located at the 5' border of the HAV IRES, we utilized an electrophoresis mobility shift assay (EMSA) to identify a 39-kDa RNA-binding protein (p39). Amino-terminal amino acid sequencing of highly purified p39 revealed absolute identity with human glyceraldehyde 3-phosphate dehydrogenase (GAPDH). The identity of p39 as simian GAPDH was further confirmed by antigenic and biochemical similarities between p39 and human GAPDH. Analysis of the RNA binding properties of simian GAPDH revealed that this cellular protein interacts with two additional sites in the HAV 5'-nontranslated RNA, one located between nucleotides 1-148 and the other between nucleotides 597-746. Competitive EMSAs also demonstrated that GAPDH and human polypyrimidine tract-binding protein, a putative picornavirus translation initiation factor, compete with each other for binding to stem-loop IIIa, suggesting that the relative cytoplasmic abundance of GAPDH and polypyrimidine tract-binding protein in individual cell-types may be an important determinant of viral translation activity. Human GAPDH was found to destabilize the folded structure of the stem-loop IIIa RNA based upon observed decreases in the circular dichroism spectra of this RNA following binding of the protein. This RNA helix-destabilizing activity of GAPDH could directly influence IRES-dependent translation and/or replication of picornavirus RNA

Networked improvement community for equity

PK-12 education is at a fascinating moment in our work to improve the overall performance of school districts that have high percentages of children who are living in poverty, come from historically disadvantaged backgrounds, do not have English as their native language and/or are atypical learners. On the one hand, we have growing evidence of strategies that serve to improve the academic performance of all students in economically, culturally, and linguistically diverse school districts [1]. On the other, there is significant variance within and across these districts as to how effectively these strategies are implemented [2]. This suggests that we know what to do in order to improve the ability of schools to best serve all children, but we face continued challenges in effectively scaling effective strategies across a district to achieve desired equity outcomes within schools that are sustained over time. The focus of this paper is to describe a planned research-practice partnership [3] that is designed to use a networked improvement community of school leaders and regional superintendents to a) build the capacity of a district to develop and implement a policy that is designed to improve equitable access to high quality learning opportunities and b) indicate ways in the implementation of this policy can serve as a driver of closing achievement and opportunity gaps for the district’s most marginalized students, by identifying and codifying measures proximal measures that capture school-based needs and practices. The first goal of this project is to increase equitable access to high quality learning for all children, the second is to demonstrate the efficacy of network improvement science technigues to implement sustainable policies with fidelity.Accepted manuscrip