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Simple Summary: The instability of viral RNA, which is susceptible to ubiquitous RNases, poses a significant challenge for its transport and detection in diagnosis. To address this challenge, this study aimed to evaluate the stability and detection limits of various RNA viruses, including the avian influenza virus, Newcastle disease virus, and African horse sickness virus, on Flinders Technology Associates cards. This investigation provides empirical evidence supporting the efficacy of Flinders Technology Associates cards for sample collection and subsequent viral RNA recovery, highlighting their suitability for use in molecular diagnostics. Consequently, based on the demonstrated effectiveness, stability, and safety implications observed in this study, Flinders Technology Associates cards are recommended for virus storage and transport, thus facilitating the molecular detection and identification of RNA viral pathogens. The Flinders Technology Associates (FTA) card, a cotton-based cellulose membrane impregnated with a chaotropic agent, effectively inactivates infectious microorganisms, lyses cellular material, and fixes nucleic acid. The aim of this study is to assess the stability and detection limit of various RNA viruses, especially the avian influenza virus (AIV), Newcastle disease virus (NDV), and African horse sickness virus (AHSV), on the FTA card, which could significantly impact virus storage and transport practices. To achieve this, each virus dilution was inoculated onto an FTA card and stored at room temperature in plastic bags for durations ranging from 1 week to 6 months. Following storage, the target genome was detected using conventional reverse transcription polymerase chain reaction. The present study demonstrated that the detection limit of AIV ranged from 1.17 to 6.17 EID50 values over durations ranging from 1 week to 5 months, while for NDV, it ranged from 2.83 to 5.83 ELD50 over the same duration. Additionally, the detection limit of AHSV was determined as 4.01 PFU for both 1 and 2 weeks, respectively. Based on the demonstrated effectiveness, stability, and safety implications observed in the study, FTA cards are recommended for virus storage and transport, thus facilitating the molecular detection and identification of RNA viral pathogens. [ABSTRACT FROM AUTHOR]

The protein actin can polymerize from monomeric globular G-actin to polymeric filamentary F-actin, under the regulation of thermodynamic variables such as temperature, pressure, and compositions of G-actin and salts. We present here new measurements of the extent of polymerization ([lowercase_phi_synonym]) of actin under pressure (P), for rabbit skeletal muscle actin in H2O buffer in the presence of adenosine triposphate and calcium ions and at low (5–15 mM) KCl concentrations. We measured [lowercase_phi_synonym] using pyrene-labeled actin, as a function of time (t) and temperature (T), for samples of fixed concentrations of initial G-actin and KCl and at fixed pressure. The [lowercase_phi_synonym](T,P) measurements at equilibrium have the same form as reported previously at 1 atm: low levels of polymerization at low temperatures, representing dimerization of the actin; an increase in [lowercase_phi_synonym] at the polymerization temperature (Tp); a maximum in [lowercase_phi_synonym](T) above Tp with a decrease in [lowercase_phi_synonym](T) beyond the maximum, indicating a depolymerization at higher T. From [lowercase_phi_synonym](T,P) at temperatures below Tp, we estimate the change in volume for the dimerization of actin, ΔVdim, to be -307±10 ml/mol at 279 K. The change of Tp with pressure dTp/dP=(0.3015±0.0009) K/MPa=(30.15±0.09) mK/atm. The [lowercase_phi_synonym](T,P) data at higher T indicate the change in volume on propagation, ΔVprop, to be +401±48 ml/mol at 301 K. The [lowercase_phi_synonym](t) measurements yield initial relaxation times rp(T) that reflect the behavior of [lowercase_phi_synonym](T) and support the presence of a depolymerization temperature. We also measured the density of polymerizing actin with a vibrating tube density meter, the results of which confirm that the data from this instrument are affected by viscosity changes and can be erroneous. [ABSTRACT FROM AUTHOR]

Studies of the dependence of actin polymerization on thermodynamic parameters are important for understanding processes in living systems, where actin polymerization and depolymerization are crucial to cell structure and movement. We report measurements of the extent of polymerization, F, of rabbit muscle actin as a function of temperature [T=(0 - 35)°C], initial G-actin concentration [[G[SUB0]]=(1 - 3) mg/ml], and initiating salt concentration [[KCl]=(5-15) mmol/l with bound Ca[SUP2+]], in H[SUB2]O and D[SUB2]O buffers and in the presence of adenosine triphosphate (ATP). A preliminary account of the data and analysis for H[SUB2]O buffers has appeared previously [P. S. Niranjan, J. G. Forbes, S. C. Greer, J. Dudowicz, K. F. Freed, and J. F. Douglas, J. Chem. Phys. 114, 10573 (2001)]. We describe the details of the studies for H[SUB2]O buffers, together with new data and analysis for D[SUB2]O buffers. The measurements show a maximum in φ(T) for H[SUB2]O buffers and D[SUB2]O buffers. For H[SUB2]O buffers, T[SUBp] decreases as either [G[SUB0]] or [KCl] increases. For D[SUB2]O buffers, T[SUBp] decreases as [KCl] increases, but T[SUBp] is not monotonic in [G[SUB0]]. The measurements are interpreted in terms of a Flory-Huggins-type lattice model that includes the essential steps: monomer activation, dimerization of activated species, and propagation of trimers to higher order polymers. The competition between monomer activation and chain propagation leads to the observed nonmonotonic variation of φ(T). The actin polymerization in D[SUB2]O buffer differs considerably from that in the H[SUB2]O buffer and underscores the significant deuterium effect on hydrophobic interactions and hydrogen bonding in the polymerization process. [ABSTRACT FROM AUTHOR]

The Flinders Technology Associates (FTA) card, a cotton-based cellulose membrane impregnated with a chaotropic agent, effectively inactivates infectious microorganisms, lyses cellular material, and fixes nucleic acid. The aim of this study is to assess the stability and detection limit of various RNA viruses, especially the avian influenza virus (AIV), Newcastle disease virus (NDV), and African horse sickness virus (AHSV), on the FTA card, which could significantly impact virus storage and transport practices. To achieve this, each virus dilution was inoculated onto an FTA card and stored at room temperature in plastic bags for durations ranging from 1 week to 6 months. Following storage, the target genome was detected using conventional reverse transcription polymerase chain reaction. The present study demonstrated that the detection limit of AIV ranged from 1.17 to 6.17 EID 50 values over durations ranging from 1 week to 5 months, while for NDV, it ranged from 2.83 to 5.83 ELD 50 over the same duration. Additionally, the detection limit of AHSV was determined as 4.01 PFU for both 1 and 2 weeks, respectively. Based on the demonstrated effectiveness, stability, and safety implications observed in the study, FTA cards are recommended for virus storage and transport, thus facilitating the molecular detection and identification of RNA viral pathogens.