Recent advances in artificial breeding and larval rearing of silver pomfret Pampus argenteus (Euphrasen 1788) in Kuwait.

During last several years, Kuwait Institute for Scientific Research (KISR), Kuwait has been trying to develop a sustainable culture technique for silver pomfret (Pampus argenteus). This paper reports the recent research advances in the breeding and rearing of silver pomfret fry at KISR. The eggs collected from wild silver pomfret during spawning seasons of 2012 to 2015 were artificially fertilized under laboratory condition. The average hatching rates of artificially fertilized eggs collected from wild silver pomfrets were 25.6%, 44.8%, 76.7%, and 53.5.0% and average survival rates of metamorphosed fry produced from these eggs were 3.7%, 5.7%, 4.4% and 3.8% for the spawning seasons 2012, 2013, 2014, and 2015, respectively. For captive brood stocks, observation on the spawning time at hourly interval by collecting eggs from the nets set at out-flow of brood tanks showed that the spawning time for captive silver pomfret starts at the time of sunset. In 2012, two groups of captive silver pomfret broods spawned a total of 62x103 and 66x103 eggs, but the eggs were unfertilized. No captive spawning occurred during 2013 and 2014 spawning season. In 2015, captive silver pomfret broods in three tanks spawned about 653x103, 673x103 and 270x103 eggs, and in 2016, the broods in four tanks spawned about 669x103, 22x103, 3x103 and 366x103 eggs. However, from these eggs only 1,400 and 1,000 fertilized eggs were collected which produced 300 and 123 hatched larvae in July 2015 and June 2016, respectively. The larvae produced from the 2015 broods did not survive beyond 56 days of metamorphosed stage while larvae produced from 2016 captive broods survived for 9 days only. The mortality of the larvae from captive brood could be related to the poor egg or milt quality. However, efforts are continued to improve the eggs and sperm quality through proper brood management.

Putrescine or spermidine binding site of aminopropyltransferases and competitive inhibitors.

A model of the active site of aminopropyltransferases was proposed based on the study of a number of monoamino and diamino compounds as potential inhibitors and substrates, respectively, of spermidine synthase purified from pig liver. The active site seems to have a relatively large hydrophobic cavity adjacent to a negatively charged site, to which a protonated amino group of putrescine binds, with another amino group of putrescine being situated in the hydrophobic cavity as a free form to be aminopropylated by decarboxylated S-adenosylmethionine. On the basis of the above-mentioned model, another modified one was proposed for spermine synthase, and several compounds mentioned model, another modified one was proposed for spermine synthase, and several compounds designed according to the modified model were found to potently inhibit spermine synthase, purified from rat brain, in competition with spermidine. The newly developed inhibitors were about two orders of magnitude more potent in vitro than a known inhibitor of spermine synthase, dimethyl(5'-adenosyl)sulfonium perchlorate.

Enhanced absorption of calcium after oral administration of maltitol in the rat intestine.

The enhancing effects of maltitol (alpha-D-glucopyranosyl-1,4-sorbitol) on absorption of calcium by the rat intestine have been studied by use of [45Ca]CaCl2 in-vivo. After intragastric administration of [45Ca]CaCl2 solution with maltitol, plasma 45Ca concentration remained at the maximum level for more than 80 min, whereas for animals given [45Ca]CaCl2 solution without maltitol, plasma 45Ca concentration declined sharply after the peak. Determination of 45Ca radioactivity remaining in the various segments of the gastrointestinal tract revealed that administration of maltitol elicited slower gastric emptying and slower intestinal transit, resulting in extensive 45Ca distribution along the small intestine throughout the experimental period. The luminal contents of the small intestine were significantly higher in rats given maltitol than in the control group. These results suggest that the enhancing action of maltitol on intestinal calcium absorption could be attributed to reduced gastrointestinal calcium transit and increased luminal fluid content, presumably because of the osmotic activity of maltitol; this would not only accelerate the dissolution of calcium into the increased luminal contents, but also enable a larger area of the small intestine to absorb calcium for a longer period of time.

[Sensory status on Bielschowsky head tilt test].

The purpose of this work was to confirm ocular deviation during head tilt in cases of superior oblique muscle palsy. Ocular vertical deviation and cyclodeviation under head tilt loading were examined in nine cases with superior oblique muscle palsy using a new device, celled a modified phase difference haploscope (M-PDH). The M-PDH is able to measure a quantitative head tilt loading towards both sides. Tests using the M-PDH revealed the difference in angle of head tilt at the onset of hyperdrift and the degree of vertical deviation during head tilt towards the paretic side. Among the cases of superior oblique muscle palsy tested, ocular vertical deviation was classified into three types depending on the angle of head tilt.

Relationship between uptake of p-hydroxybenzoic acid esters by Escherichia coli and antibacterial activity.

The relationship between the uptake and antimicrobial activity of p-hydroxybenzoic acid esters (parabens) was studied using Escherichia coli. The uptake into bacterial cells and the antibacterial activity of parabens were logarithmically proportional to the carbon number of the alkyl group from methyl to butyl paraben. The free energy change for the transfer of the methylene group of parabens from the aqueous to the cell phase was less than that obtained from the n-hexane and n-octanol-water partition systems. This demonstrates that the hydrophilicity of the cells is larger than n-hexane and n-octanol. The uptake of hydrophobic ethyl benzoate was less than that of the more hydrophilic butyl paraben possessing a phenolic hydroxyl group. Parabens may thus be incorporated into cells by both hydrophobic and hydrophilic interactions. The apparent concentration of parabens in the bacterial cells required to produce the same antibacterial activity decreased logarithmically with an increasing carbon number of the alkyl group. The dependence of the antibacterial activity of parabens on the alkyl chain length may thus be concluded to be due to the alkyl group, not only for uptake into bacterial cells but also for accumulation or concentration on biological receptors after incorporation into the cells.

Effects of the structures of polyoxyethylene alkyl ethers on uptake of butyl p-hydroxybenzoate by Escherichia coli and its antibacterial activity.

The effects of the structures of non-ionic surfactants on the uptake of butyl p-hydroxybenzoate (BP) into Escherichia coli cells and its antibacterial activity were systematically studied using polyoxyethylene alkyl ethers (PAEs) possessing various oxyethylene and hydrocarbon chain lengths. The uptake of BP into bacterial cells in an aqueous PAE solution was proportional to free BP in an aqueous phase, depending on the structures of PAEs. The antibacterial activity of BP decreased in the presence of PAEs, whereas it was greater than that anticipated from free BP. However, only PAE with 12 carbons in the hydrophobic group caused unusual increases in the uptake and antibacterial activity of BP, and the surfactant was more extensively incorporated into bacterial cells, differing from other PAEs, which were much less incorporated. The PAEs were thus concluded to increase the susceptibility of bacteria against BP due to direct interactions with the cells. Particularly, the PAE with 12 carbons in the hydrophobic group, which penetrated abundantly into the cells, might result in an increase in the fluidity of the cellular lipid matrix and a decrease in the resistance of drug permeation.

Polyamine-linked sepharoses: preparation and application to mammalian spermine synthase.

Seven different polyamine-linked Sepharose derivatives were prepared for the affinity chromatography of spermidine and spermine binding macromolecules: Spermine synthase from rat and hog brain was used as a model protein with a spermidine binding site. Comparative studies of the affinities of the enzymes for the seven matrixes suggested that two negative charges, three to four methylene groups apart, should be present at the decarboxylated S-adenosylmethionine binding site and should improve the binding of the enzyme to the Sepharose derivative. Two negative charges at the spermidine binding site would be expected to do the same. Three affinity matrixes linked with 1,17-diamino-4,9,14-triazaheptadecane, 1,21-diamino-4,9,13,18-tetraazaheneicosane, and 5-spermine carboxylic acid, respectively, had an affinity for spermine synthases higher than that of spermine-Sepharose, which has been used for the purification of spermine synthase. The first of these matrixes was used and proved to be effective for the purification.