Aiming to clarify the mechanism of inhibition of (Na super(+), K super(+))-ATPase activity by polyamines, we examined the effects of exogenous putrescine, spermidine, and spermine on the kinetic ...behavior of phosphoenzyme-linked partial reactions using a microsomal gill (Na super(+), K super(+))-ATPase from juvenile and adult M. amazonicum, a freshwater palaemonid shrimp. The time course of phosphointermediate formation is greater (0.089 plus or minus 0.006 s super(-1)) in adults than in juveniles (0.053 plus or minus 0.003 s super(-1)) for spermidine, but similar to juveniles (0.059 plus or minus 0.004 s super(-1)) for putrescine. Maximum phosphointermediate formation for the (Na super(+), K super(+))-ATPase from juveniles decreased by 46% and 32% with spermidine and putrescine, respectively. In adults, maximum phosphointermediate levels decreased by 50% and 8%, respectively. For both spermidine and putrescine, dephosphorylation rates were higher for adults than for juveniles, and were higher than in controls without polyamines. Spermine had a negligible effect (<10%) on phosphorylation/dephosphorylation rates of both juvenile and adult enzymes. This is the first report on the effects of polyamines on phosphoenzyme-linked partial reactions in juvenile and adult M. amazonicum gill (Na super(+), K super(+))-ATPases. Our findings suggest that the phosphorylation/dephosphorylation steps of this gill enzyme may be regulated by polyamines during ontogenetic development.
Prior to sequencing PCR products, it is necessary to remove remaining primers and unincorporated nucleotides from the reaction. HT ExoSAP-IT Fast reagent is an effective enzymatic cleanup method that ...combines Exonuclease I and Shrimp Alkaline Phosphatase (SAP) for a simple, one-step treatment that yields superior sequencing results. HT ExoSAP-IT Fast reagent decreases protocol time to 14 minutes (7 min at 37degreesC followed by 7 min at 80degreesC). With its low viscosity formulation, it can be stored long-term at -20degreesC or short-term at 4degreesC without loss of function, and is ideal for robotics platforms or multichannel pipetting. The new version expands the format options to offer a 96-well plate with customizable volumes for high-throughput users.
As a procedural best practice, it is recommended that PCR products are cleaned up following initial amplification and prior to Sanger Sequencing. The goal of PCR product cleanup is to eliminate ...leftover primers and nucleotides that interfere with the sequencing reaction and lead to poor results. A speedy and efficient way to do this is with enzymes that digest excess PCR primers and degrade unincorporated nucleotides. The most effective and well referenced product for this is ExoSAP-IT reagent from Affymetrix(R), which combines Exonuclease I primer digestion and Shrimp Alkaline Phosphatase nucleotide degradation into a single cleanup step. HT ExoSAP-IT Fast High-Throughput PCR Product Cleanup is the ideal solution in high volume labs with quick sample turnaround requirements. HT ExoSAP-IT Fast reagent has a 14 minute total protocol time, which is over 50% faster than standard ExoSAP-IT reagent. It is added directly to the PCR product for a 7 minute cleanup at 37degreesC, followed by a 7 minute inactivation at 80degreesC.
This study was aimed at evaluating crab shell chitosan as absorption enhancer in ciprofloxacin tablet formulation using the ex-vivo model. Six batches of ciprofloxacin tablets containing varying ...concentrations of crab shell-derived chitosan ranging from 0 to 5% super(w)/w at 1% super(w)/w intervals were produced. Batch CTS-0 containing no chitosan served as the control. The crushing strength, friability, disintegration time, dissolution profile and permeation profile of all the batches were determined. Friability was not significantly affected but the crushing strength and disintegration time of tablets decreased with increase in concentration of chitosan. There was no significant difference in the cumulative percent drug released in 1 h but the cumulative percent drug permeated in 4 h increased with increase in the concentration of chitosan. It increased from 68% (when no chitosan was added) to 81.8% (when 5% super(w)/w chitosan was incorporated). The polymer caused a faster onset of drug release but the eventual total drug released was not significantly influenced. It also improved the permeation of the released drug. This study correlates with in-vivo bioavailability study because the usual oral bioavailability of ciprofloxacin without absorption enhancer is 70%. Hence, crab shell chitosan at concentration of 5% super(w)/w could increase the absorption of ciprofloxacin from 70 to 82%. The study suggests the use of the chitosan at this concentration to improve the absorption of ciprofloxacin.
Contamination of the aqueous environment by heavy metals and due to the discharge of metal containing effluents into the water bodies is one of the environmental issues of the century. Thus, in this ...work, the main concern has been the preparation of chitin and chitosan from the raw materials of shrimp shells and the characterization of the prepared chitosan by field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FTIR). The work was then shifted to investigate the potentiality of Cr super(+6) adsorption with the prepared chitosan. The controlled parameters of adsorption process were studied. The percentage of Cr super(+6) removal using the shrimp chitosan was 64.29%.
General mechanism for exaggerated sexuallyselected traits. Many animals wield sexually-selected exaggerated traits. 'Classic' examples include the peacock's train, and the antlers observed in male ...deer, as well as fiddler crabs with enlarged claws, and the enlarged head-horns of rhinoceros beetles (Trypoxylus dichotomus, cover). These traits are used for mate choice, or to deter rival males, because they act as unusually reliable signals of the condition of individual males: only the best-quality animals produce full-sized signal structures. But what keeps their expression honest? How can signal traits evolve that are resistant to invasion by cheaters who fake attractive signals? The answer may lie in the ancient insulin-like signalling pathway, which is found in all animals and directly links individual condition to growth in a dose dependent manner. Warren et al. discuss recent evidence suggesting that exaggerated sexually-selected signal traits arise when specific structures become extra-sensitive to physiological signals like insulins or insulin-like growth factors (pages 889-899).
Enzymes are able to bind to their substrates specifically at the active site. The proximity and orientation of the substrates strongly increase the likelihood that productive E-S complexes will ...arise. Treated chitin (powder or flake) is more efficient than crystalline chitin. This is because the latter is less active due to its insolubility. The structure of treated chitin is opened; this facilitates its interaction with the enzyme. The purpose of this research was to create a kind of modified chitin and study the characterization of the different types of chitin including functional groups by IR spectrophotometer, pore size, surface area and crystallinity by X-Ray diffraction. Chitin from shrimp shell was modified into colloidal, bead, amorphous and superfine chitin. The results of the IR spectra of colloidal and bead chitin showed a similar pattern with chitin powder; they peaked at 3447 and 3113 cm super(-1) (OH and NH sub(2) groups), 1645 cm super(-1) (amide groups N-H) and 1071 cm super(-1) (group C-O). Superfine and amorphous chitin had similar absorbance with powder chitin but appeared to peak in the fingerprint region. Characterization of physical properties based on the pore size and surface area of powder, colloidal, superfine, amorphous and bead chitin changed the pore radius of each type of chitin due to the treatment of swelling. Crystallinity showed that specific diffractogram pattern in the three main peaks 2q was 9.5, 19.5 and 26 with varying intensity. Chitinase activity assay using modified types of chitin substrate had higher values than chitin powder. The highest activity was in amorphous chitin with values of 1.858 U/mL. This is because it has chitin chain and the rearrangement of its structure was more open, facilitating its interaction with enzyme.
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