11 research outputs found
Measurement of changes in muscle viscoelasticity during static stretching using stress-relaxation data
This study investigates how the viscoelasticity of the muscle changes during
static stretching by measuring the state of the muscle during stretching using
continuous time-series data. We used a device that applied a force to the
muscle during stretching and measured the reaction force. The device was
attached to the participants, and time-series data of the reaction force
(stress-relaxation data) during stretching were obtained. A model using
fractional calculus (spring-pot model) was selected as the viscoelastic model
for the muscle, in which the data for stress relaxation were fitted on a
straight line on a both logarithmic plot. The experimental stress-relaxation
results showed that viscoelasticity tended to change abruptly at a particular
time during static stretching because the stress-relaxation data were
represented by a broken line comprising two segments on the both logarithmic
plot. Considering two states of viscoelasticity, before and after the change,
the stress-relaxation curve was fitted to the spring-pot model with high
accuracy using segment regression (R2 = 0.99). We compared the parameters of
the spring-pot model before and after the change in muscle viscoelasticity. By
examining these continuous time-series data, we also investigated the time
taken for the effects of stretching to become apparent. Furthermore, by
measuring the changes in muscle viscoelasticity during static stretching before
and after a short-term exercise load of running on a treadmill, we examined the
effects of short-term exercise load on the changes in viscoelasticity during
static stretching
Molecular Cloning and Expression Analysis of fushi tarazu Factor 1 in the Brain of Air-Breathing Catfish, Clarias gariepinus
BACKGROUND: Fushi tarazu factor 1 (FTZ-F1) encodes an orphan nuclear receptor belonging to the nuclear receptor family 5A (NR5A) which includes adrenal 4-binding protein or steroidogenic factor-1 (Ad4BP/SF-1) and liver receptor homologue 1 (LRH-1) and plays a pivotal role in the regulation of aromatases. METHODOLOGY/PRINCIPAL FINDINGS: Present study was aimed to understand the importance of FTZ-F1 in relation to brain aromatase (cyp19a1b) during development, recrudescence and after human chorionic gonadotropin (hCG) induction. Initially, we cloned FTZ-F1 from the brain of air-breathing catfish, Clarias gariepinus through degenerate primer RT-PCR and RACE. Its sequence analysis revealed high homology with other NR5A1 group members Ad4BP/SF-1 and LRH-1, and also analogous to the spatial expression pattern of the latter. In order to draw functional correlation of cyp19a1b and FTZ-F1, we analyzed the expression pattern of the latter in brain during gonadal ontogeny, which revealed early expression during gonadal differentiation. The tissue distribution both at transcript and protein levels revealed its prominent expression in brain along with liver, kidney and testis. The expression pattern of brain FTZ-F1 during reproductive cycle and after hCG induction, in vivo was analogous to that of cyp19a1b shown in our earlier study indicating its involvement in recrudescence. CONCLUSIONS/SIGNIFICANCE: Based on our previous results on cyp19a1b and the present data, it is plausible to implicate potential roles for brain FTZ-F1 in ovarian differentiation and recrudescence process probably through regulation of cyp19a1b in teleosts. Nevertheless, these interactions would require primary coordinated response from ovarian aromatase and its related transcription factors
The Schizosaccharomyces pombe Hsp104 Disaggregase Is Unable to Propagate the [PSI+] Prion
The molecular chaperone Hsp104 is a crucial factor in the acquisition of thermotolerance in yeast. Under stress conditions, the disaggregase activity of Hsp104 facilitates the reactivation of misfolded proteins. Hsp104 is also involved in the propagation of fungal prions. For instance, the well-characterized [PSI+] prion of Saccharomyces cerevisiae does not propagate in Δhsp104 cells or in cells overexpressing Hsp104. In this study, we characterized the functional homolog of Hsp104 from Schizosaccharomyces pombe (Sp_Hsp104). As its S. cerevisiae counterpart, Sp_hsp104+ is heat-inducible and required for thermotolerance in S. pombe. Sp_Hsp104 displays low disaggregase activity and cannot propagate the [PSI+] prion in S. cerevisiae. When overexpressed in S. cerevisiae, Sp_Hsp104 confers thermotolerance to Δhsp104 cells and reactivates heat-aggregated proteins. However, overexpression of Sp_Hsp104 does not propagate nor eliminate [PSI+]. Strikingly, [PSI+] was cured by overexpression of a chimeric chaperone bearing the C-terminal domain (CTD) of the S. cerevisiae Hsp104 protein. Our study demonstrates that the ability to untangle aggregated proteins is conserved between the S. pombe and S. cerevisiae Hsp104 homologs, and points to a role of the CTD in the propagation of the S. cerevisiae [PSI+] prion