Physical stress on halibut larvae

Halibut larvae were exposed to physical stress in the form of different levels of airation. Survival rate, development, dry weight, RNA, DNA and protein were measured. At the end of the experiment the larvae exposed to gentle airation had the highest survival rate, total dry weight, dry weight of the yolk sac, content of RNA and RNA-DNA ratio. However, the group without airation had the highest dry weight of larval body, growth rate and yolk conversion efficiency. The functional jaw development had the same value and were highest in these two groups

Physical stress on halibut larvae

Halibut larvae were exposed to physical stress in the form of different levels of airation. Survival rate, development, dry weight, RNA, DNA and protein were measured. At the end of the experiment the larvae exposed to gentle airation had the highest survival rate, total dry weight, dry weight of the yolk sac, content of RNA and RNA-DNA ratio. However, the group without airation had the highest dry weight of larval body, growth rate and yolk conversion efficiency. The functional jaw development had the same value and were highest in these two groups

The Host-Pathogen interaction of human cyclophilin A and HIV-1 Vpr requires specific N-terminal and novel C-terminal domains

<p>Abstract</p> <p>Background</p> <p>Cyclophilin A (CypA) represents a potential key molecule in future antiretroviral therapy since inhibition of CypA suppresses human immunodeficiency virus type 1 (HIV-1) replication. CypA interacts with the virus proteins Capsid (CA) and Vpr, however, the mechanism through which CypA influences HIV-1 infectivity still remains unclear.</p> <p>Results</p> <p>Here the interaction of full-length HIV-1 Vpr with the host cellular factor CypA has been characterized and quantified by surface plasmon resonance spectroscopy. A C-terminal region of Vpr, comprising the 16 residues ⁷⁵GCRHSRIGVTRQRRAR⁹⁰, with high binding affinity for CypA has been identified. This region of Vpr does not contain any proline residues but binds much more strongly to CypA than the previously characterized N-terminal binding domain of Vpr, and is thus the first protein binding domain to CypA described involving no proline residues. The fact that the mutant peptide Vpr^75-90R80A binds more weakly to CypA than the wild-type peptide confirms that Arg-80 is a key residue in the C-terminal binding domain. The N- and C-terminal binding regions of full-length Vpr bind cooperatively to CypA and have allowed a model of the complex to be created. The dissociation constant of full-length Vpr to CypA was determined to be approximately 320 nM, indicating that the binding may be stronger than that of the well characterized interaction of HIV-1 CA with CypA.</p> <p>Conclusions</p> <p>For the first time the interaction of full-length Vpr and CypA has been characterized and quantified. A non-proline-containing 16-residue region of C-terminal Vpr which binds specifically to CypA with similar high affinity as full-length Vpr has been identified. The fact that this is the first non-proline containing binding motif of any protein found to bind to CypA, changes the view on how CypA is able to interact with other proteins. It is interesting to note that several previously reported key functions of HIV-1 Vpr are associated with the identified N- and C-terminal binding domains of the protein to CypA.</p

The intriguing Cyclophilin A-HIV-1 Vpr interaction: prolyl cis/trans isomerisation catalysis and specific binding

<p>Abstract</p> <p>Background</p> <p>Cyclophilin A (CypA) represents a potential target for antiretroviral therapy since inhibition of CypA suppresses human immunodeficiency virus type 1 (HIV-1) replication, although the mechanism through which CypA modulates HIV-1 infectivity still remains unclear. The interaction of HIV-1 viral protein R (Vpr) with the human peptidyl prolyl isomerase CypA is known to occur <it>in vitro </it>and <it>in vivo</it>. However, the nature of the interaction of CypA with Pro-35 of N-terminal Vpr has remained undefined.</p> <p>Results</p> <p>Characterization of the interactions of human CypA with N-terminal peptides of HIV-1 Vpr has been achieved using a combination of nuclear magnetic resonace (NMR) exchange spectroscopy and surface plasmon resonance spectroscopy (SPR). NMR data at atomic resolution indicate prolyl <it>cis</it>/<it>trans </it>isomerisation of the highly conserved proline residues Pro-5, -10, -14 and -35 of Vpr are catalyzed by human CypA and require only very low concentrations of the isomerase relative to that of the peptide substrates. Of the N-terminal peptides of Vpr only those containing Pro-35 bind to CypA in a biosensor assay. SPR studies of specific N-terminal peptides with decreasing numbers of residues revealed that a seven-residue motif centred at Pro-35 consisting of RHFPRIW, which under membrane-like solution conditions comprises the loop region connecting helix 1 and 2 of Vpr and the two terminal residues of helix 1, is sufficient to maintain strong specific binding.</p> <p>Conclusions</p> <p>Only N-terminal peptides of Vpr containing Pro-35, which appears to be vital for manifold functions of Vpr, bind to CypA in a biosensor assay. This indicates that Pro-35 is essential for a specific CypA-Vpr binding interaction, in contrast to the general prolyl <it>cis</it>/<it>trans </it>isomerisation observed for all proline residues of Vpr, which only involve transient enzyme-substrate interactions. Previously suggested models depicting CypA as a chaperone that plays a role in HIV-1 virulence are now supported by our data. In detail the SPR data of this interaction were compatible with a two-state binding interaction model that involves a conformational change during binding. This is in accord with the structural changes observed by NMR suggesting CypA catalyzes the prolyl <it>cis/trans </it>interconversion during binding to the RHFP³⁵RIW motif of N-terminal Vpr.</p

Artificial hatching substrate, effect on RNA / DNA ratio and protein retention during the yolk-sac period of Atlantic salmon (Salmo salar)

Genetical groups of Atlantic salmon (Salmo salar) were hatched in a Caiifonian hatching system with and without an astro-turf artificial hatching substrate, and were later transfered to separate feeding units. The substrate reared (ATR) alevins grew faster, absorbed the yolk faster and more efficient, and absorbed protein from the yolk faster and more efficient, than flat screen reared (FSR) alevins. Protein synthesis, RNA content, DNA content, and the RNA-DNA ratio were higher in favour of the substrate reared alevins. The differeces in disfavour of the FSR alevins are probably due to high activity stress. After commencement of first feeding the ATR fry grew faster, and RNA content and DNA content were higher than in the FSR fry. However a difference in specific growth rate in favour of the FSR fry was observed at the end of the experiment. The RNA-DNA ratio was in favour of the ATR fry immediatly after commencement of first feeding, but in favour of the FSR fry at the end of the experiment

Studies on the chemical structure of cod egg chorion

The chemical structure of the cod egg chorion has been investigated in preparations of chorion obtained after decompression rupture of cod eggs. The chorion was purified free of non-integral components by sucrose gradient centrifugation or by membrane filtration. Both preparations of cod egg chorion were shown to be almost entirely proteinaceous in nature, with only minor amounts of carbohydrates present. The protein units of the chorion displayed molecular sizes and amino acid composition akin to the keratin class of proteins. The modifications and developmental fate of chorion keratins are discussed