Characterization of two classes of ribonucleoprotein complexes possibly involved in RNA editing from Leishmania tarentolae mitochondria.

The molecular mechanism of RNA editing in trypanosomatid mitochondria is an unsolved problem. We show that two classes of ribonucleoprotein complexes exist in a mitochondrial extract from Leishmania tarentolae and appear to be involved in RNA editing. The 'G' class of RNP complexes consists of 170-300 A particles which contain guide RNAs and proteins, show little terminal uridylyl transferase (TUTase) activity and exhibit an in vitro RNA editing-like activity. The 'T' class consists of approximately six RNP complexes, the endogenous RNA of which can be self-labeled with [alpha-32P]UTP. The most abundant T complex, T-IV, is visualized by electron microscopy as 80-140 A particles. This complex exhibits TUTase activity in the native gel and contains guide RNAs. Both G and T complexes are possibly involved with RNA editing in vivo. These results are a starting point for the analysis of the biochemistry of RNA editing.     

Manipulating national identity: the strategic use of rhetoric by supporters and opponents of the ‘Cronulla riots’ in Australia

This research explores the role of opinion-based groups in understanding responses to racist violence such as the 2005 Cronulla riots in Australia. Traditionally, explanations of collective action in social psychology and sociology focus on conflict between broad social categories. We propose that the responses to the riots can be understood not only as inter-group conflict between Muslims and non-Muslims, or an in-group argument amongst non-Muslims, but as a bona fide inter-group conflict between supporters and opponents of the riots. We argue that these groups use rhetoric in attempts to claim dominant status within society by aligning their identities with positively valued social categories such as ethnicities and national identities. The analysis of rhetoric from the groups supporting and opposing the riots demonstrates consistent, albeit contested, attempts to align support for the riot with the Australian national category in conflict with countervailing attempts to align opposition to the riot with the same national category.     

Evidence for new C-terminally truncated variants of α- and β-tubulins

Cellular α-tubulin can bear various carboxy-terminal sequences: full-length tubulin arising from gene neosynthesis is tyrosinated, and two truncated variants, corresponding to detyrosinated and Δ2 α‑tubulin, result from the sequential cleavage of one or two C-terminal residues, respectively. Here, by using a novel antibody named 3EG that is highly specific to the –EEEG C-terminal sequence, we demonstrate the occurrence in neuronal tissues of a new αΔ3‑tubulin variant corresponding to α1A/B‑tubulin deleted of its last three residues (EEY). αΔ3‑tubulin has a specific distribution pattern: its quantity in the brain is similar to that of αΔ2-tubulin around birth but is much lower in adult tissue. This truncated α1A/B-tubulin variant can be generated from αΔ2-tubulin by the deglutamylases CCP1, CCP4, CCP5, and CCP6 but not by CCP2 and CCP3. Moreover, using 3EG antibody, we identify a C‑terminally truncated β-tubulin form with the same –EEEG C-terminal sequence. Using mass spectrometry, we demonstrate that β2A/B-tubulin is modified by truncation of the four C-terminal residues (EDEA). We show that this newly identified βΔ4-tubulin is ubiquitously present in cells and tissues and that its level is constant throughout the cell cycle. These new C-terminally truncated α- and β-tubulin variants, both ending with –EEEG sequence, are expected to regulate microtubule physiology. Of interest, the αΔ3-tubulin seems to be related to dynamic microtubules, resembling tyrosinated-tubulin rather than the other truncated variants, and may have critical function(s) in neuronal development.     

Contrasting patterns in trophic niche evolution of polymorphic Arctic charr populations in two subarctic Norwegian lakes

Hydrobiologia - Lipid biomarkers in sediments, which are indicative of biological production, provide important information regarding the environmental conditions in and around lakes, and can be...     

Role of the 3' splice site in U12-dependent intron splicing

U12-dependent introns containing alterations of the 3' splice site AC dinucleotide or alterations in the spacing between the branch site and the 3' splice site were examined for their effects on splice site selection in vivo and in vitro. Using an intron with a 5' splice site AU dinucleotide, any nucleotide could serve as the 3'-terminal nucleotide, although a C residue was most active, while a U residue was least active. The penultimate A residue, by contrast, was essential for 3' splice site function. A branch site-to-3' splice site spacing of less than 10 or more than 20 nucleotides strongly activated alternative 3' splice sites. A strong preference for a spacing of about 12 nucleotides was observed. The combined in vivo and in vitro results suggest that the branch site is recognized in the absence of an active 3' splice site but that formation of the prespliceosomal complex A requires an active 3' splice site. Furthermore, the U12-type spliceosome appears to be unable to scan for a distal 3' splice site.     

Ion-mediated resistance to osmotic changes of ram spermatozoa: the role of amiloride and ouabain

The aim of this study was to evaluate whether the Na+/K+ and Na+/H+ exchange can maintain the function of fresh ram spermatozoa. We analyzed the quality parameters of spermatozoa from fresh ram ejaculates incubated in iso- (about 300 mOsm), hypo- (about 100 mOsm) and hyperosmotic (about 900 mOsm) media in the presence of ouabain a specific inhibitor of the Na+/K+ ATP-ase or amiloride, a specific inhibitor of the Na+/H+ antiporter. Ouabain increased the percentage of morphologically altered acrosomes in isoosmotic media (from about 10% to 15% in control to about 30% with 10(-4) M ouabain) and decreased the percentage of total motility (from about 80% in control to about 50% to 55% with 10(-4) M ouabain). Ouabain decreased the mean linearity component of motility and decreased the frequency of head displacement. The addition of ouabain increased the percentage of altered acrosomes in the hypo- and hyperosmotic media, although it did not modify viability in either media. Ouabain also increased the percentage of swollen tails in the hypoosmotic medium at higher concentrations of the inhibitor. Amiloride increased the percentage of altered acrosomes in all media although its effect was less intense than that of ouabain. In isoosmotic media, total motility was decreased from about 80% in control to about 65% with 10(-4) M amiloride. Motile spermatozoa incubated with amiloride showed a clear decrease of mean velocity and mean linearity and increased frequency of head displacement. In the hyperosmotic medium, adding amiloride decreased the percentage of viability and altered tails at concentrations as low as 10(-6) to 10(-5) M. Our results indicate that the active mechanisms which control Na+ transport play a significant role in the maintenance of function in ram spermatozoa subjected to different osmotic environments. These mechanisms may be important in maintaining ram sperm function both "in vivo" and "in vitro".     

Multistage Background Field Removal (MUBAFIRE)—Compensating for B 0 Distortions at Ultra-High Field

The investigation of tissue magnetic susceptibility and the resultant magnetic field offers a new avenue for quantitative tissue characterisation by MRI. One crucial step in mining the phase and field data for relevant tissue information is the correction of externally induced field shifts. This article outlines a multistep approach comprising several methodologies for background field removal. The virtues of B ₀ long-range variation detection and compensation of more localised external disturbances are unified in a sequential filter chain. The algorithm is tested by means of a numerical Monte Carlo simulation model and applied to in vivo measurements at 3T and 9.4T as well as to a fixed brain tissue measurement at 9.4T. Further, a comparison to conventional filter types has been undertaken.     

Reliability and Validity of Selected PROMIS Measures in People with Rheumatoid Arthritis

Purpose

To evaluate the reliability and validity of 11 PROMIS measures to assess symptoms and impacts identified as important by people with rheumatoid arthritis (RA).

Methods

Consecutive patients (N = 177) in an observational study completed PROMIS computer adapted tests (CATs) and a short form (SF) assessing pain, fatigue, physical function, mood, sleep, and participation. We assessed test-test reliability and internal consistency using correlation and Cronbach’s alpha. We assessed convergent validity by examining Pearson correlations between PROMIS measures and existing measures of similar domains and known groups validity by comparing scores across disease activity levels using ANOVA.

Results

Participants were mostly female (82%) and white (83%) with mean (SD) age of 56 (13) years; 24% had ≤ high school, 29% had RA ≤ 5 years with 13% ≤ 2 years, and 22% were disabled. PROMIS Physical Function, Pain Interference and Fatigue instruments correlated moderately to strongly (rho’s ≥ 0.68) with corresponding PROs. Test-retest reliability ranged from .725–.883, and Cronbach’s alpha from .906–.991. A dose-response relationship with disease activity was evident in Physical Function with similar trends in other scales except Anger.

Conclusions

These data provide preliminary evidence of reliability and construct validity of PROMIS CATs to assess RA symptoms and impacts, and feasibility of use in clinical care. PROMIS instruments captured the experiences of RA patients across the broad continuum of RA symptoms and function, especially at low disease activity levels. Future research is needed to evaluate performance in relevant subgroups, assess responsiveness and identify clinically meaningful changes.