Improvement of motility and fertilization potential of postthaw human sperm using glutamine

The effectiveness of three amino acids, glutamine, proline, and histidine, and one amino acid-related compound, betaine, in preserving human sperm diluted v/v in a basal medium (BM) containing 14% glycerol during the freeze-thaw (FT) process was studied. At 80 mM in BM, only glutamine improved the 5- to 60-min postthaw total and progressive motilities and velocity. The presence of glutamine at 80 mM is not sufficient to achieve lower concentrations of the toxic agent glycerol in FT medium. Glutamine may therefore have a mechanism of protection on human spermatozoa that is independent from that of glycerol. The zona-free hamster egg penetration test showed that the percentage of eggs penetrated was significantly greater when spermatozoa were frozen-thawed with 80 mM glutamine in BM. Consequently, the presence of glutamine at 80 mM in a glycerol-FT medium maintains human sperm motility and fertilizing ability during the FT process.

Rationalization of the effects of compatible solutes on protein stability in terms of thermodynamic nonideality

Inhibition by compatible solutes such as proline and glycine betaine of the rate of coagulation, at 60 degrees C, of bovine serum albumin in 0.1 M acetate buffer, pH 5, is used as a model system to substantiate the concept that the production of high concentrations of osmolytes by plants and other organisms in response to stress (e.g., drought) results in stabilization of native enzyme structures via nonspecific excluded volume effects. The paradoxical situation whereby this effect of compatible solutes counters to some extent the protein-precipitating effect of poly(ethylene glycol) is also seemingly resolved.

Dielectric properties of the system bovine albumin: urea: betaine in aqueous solution

Urea (about 5 mol l-1) causes an approximately five-fold increase of the dielectric increment of bovine serum albumin at 20 degrees C. The increase is reversed by betaine (about 2.5 mol l-1), or prevented if urea and betaine are added together. This result can be seen as an electric counterpart to the protective role of osmolytes which are secreted by cells and tissues subjected to various types of internal or environmental stress.

Osmoprotective activity for Escherichia coli in mammalian renal inner medulla and urine. Correlation of glycine and proline betaines and sorbitol with response to osmotic loads

Escherichia coli are protected against hypertonic NaCl by human urine. We have shown that this is due in part to the presence of glycine betaine and proline betaine. Several investigators have proposed that betaines and sorbitol are concentrated in the cells of the renal inner medulla where they exert a protective role against urea and extracellular osmotic forces. E. coli was used in the present studies as an "osmosensor" to detect osmoprotective activity in mammalian tissues. The greatest activity was found in extracts of renal inner medulla and to a lesser extent in the renal outer medulla and cortex of several mammalian species. Liver extracts were more active than other nonrenal tissues. Bacterial osmoprotective activity and concentration of glycine betaine in the renal inner medulla of rabbits were found to correlate closely with urinary osmolarity. Concentrations of sorbitol were found to be also increased in the renal inner medulla during osmotic stress, but this compound is not osmoprotective for E. coli. Glycine and proline betaine were recovered in urine of rabbits and were increased in those given high osmotic loads. Only small amounts of proline betaine were recovered in the renal inner medulla. The source from which proline betaine is derived is unknown.

Isolation of glycine betaine and proline betaine from human urine. Assessment of their role as osmoprotective agents for bacteria and the kidney

Human urine is osmoprotective for enteric bacteria, permitting E. coli to grow with high concentrations of NaCl and other salts and even higher concentrations of sucrose and mannitol but not urea. The active material in urine is soluble in methanol and is precipitated by ammonium reineckate at acid pH. Using gel filtration and high-pressure liquid chromatography, we have identified two major osmoprotective compounds in urine. One is glycine betaine; the other is proline betaine as demonstrated by nuclear magnetic resonance, mass spectrum scanning, and chemical synthesis. Proline betaine has not been described previously to our knowledge in vertebrate tissues. It is known to be a cell volume-regulating agent for marine red algae and the euryhaline mollusk Elysia chloritica. We suggest that the presence of glycine and proline betaines in human urine may reflect an osmoprotective role for the kidney and that they protect bacteria in the urine only fortuitously.

Osmoregulation in Escherichia coli by accumulation of organic osmolytes: betaines, glutamic acid, and trehalose

It has been shown previously that externally added glycine betaine is accumulated in Escherichia coli in response to the external osmotic strength. Here we have shown, by using nuclear magnetic resonance spectroscopy and radiochemical methods, that E. coli growing in a glucose-mineral medium of elevated osmotic strength generated with NaCl, had the same capacity to accumulate proline betaine and glycine betaine. Its capacity to accumulate gamma-butyrobetaine was, however, 40 to 50% lower. Accordingly, externally added proline betaine and glycine betaine stimulated aerobic growth of osmotically stressed cells equally well, and they were more osmoprotective than gamma-butyrobetaine. In cells grown at an osmotic strength of 0.64, 1.01, or 1.47 osmolal, respectively, the molal cytoplasmic concentration of the two former betaines corresponded to 29, 38, or 58% of the external osmotic strength. Nuclear magnetic resonance spectroscopy revealed that trehalose and glutamic acid were the only species of organic osmolytes accumulated in significant amounts in cells grown under osmotic stress in glucose-mineral medium without betaines. Their combined molal concentration in the cytoplasm of cells grown at 1.01 osmolal corresponded to 27% of the external osmotic strength.

High-performance liquid chromatography of tRNAs on novel stationary phases

Rapid separation of a group of tRNAs was carried out on novel siliceous bonded stationary phases with aqueous eluents by using gradient elution with increasing or decreasing salt gradient, as usual in electrostatic interaction chromatography or hydrophobic interaction chromatography, respectively. The stationary phases consist of microparticulate macroporous silica with surface-bound polar moieties, containing weak cationic and/or hydrophobic binding sites. Depending on the nature of the binding sites, the stationary phases exhibit different retention behavior and selectivity for tRNAs. Aqueous phosphate solutions were used as the eluent, and in many cases isocratic elution was sufficient to separate seven tRNAs. Addition of magnesium ions or n-decylbetaine to the eluent resulted in lower retention, the latter causing a greater increase in the eluent strength. The optimum pH range of the eluent was 5.5-6.5.

Processing of olfactory information at three neuronal levels in the spiny lobster

Odor quality coding was analyzed at three neuronal levels, receptor cells and two levels of chemosensory interneurons, in the olfactory system of the spiny lobster Panulirus argus . Responses to three of the most stimulatory compounds for this animal - taurine, glutamate and betaine - were recorded at each level in order to compare basic neuronal response properties, single cell and population response spectra, and across-neuron patterns. Mean response specificity increased for cells at each successive neuronal level. The increase in breadth of tuning between receptor cells and low-order interneurons was paralleled by an increase in interstimulus across-neuron correlations. However, in high-order interneurons, there was a relative decline in across-neuron correlations, indicating that the more broadly-tuned high-order interneurons are better able to discriminate between any two compounds than are the more narrowly-tuned low-order interneurons. Although stimulus quality appears to be coded by interneurons as an across-fiber pattern, the fact that some low-order and high-order interneurons retained the narrow specificity of receptor cells suggests that labeled lines may have an important function in coding throughout the olfactory pathway of the spiny lobster.

Enzymatic determination of phospholipase D activity with choline oxidase

A new enzymatic method was developed for the assay of phospholipase D [phosphatidylcholine phosphatidohydrolase EC 3.1.4.4] from cabbage leaves using choline oxidase from Arthrobacter globiformis cells. The method was based on the estimation of choline by the following series of enzymatic reactions after ending the phospholipase D reaction: Choline + 202 + h2o Choline oxidase Betaine + 2H2O2 2H2O2 + Phenol + 4-Aminoantipyrine Peroxidase Quinoneimine dye + 4H2O The amount of choline was proportional to the amount of resulting quinoneimine dye with an absorbance maximum at 500 nm. The phospholipase D reaction (choline liberation) was carried out at pH 5.5 in the presence of Ca2+ ions and ended by adding EDTA in conc. Tris-HCl buffer, pH 8, to give a final pH of around 8. The initial rate of the phospholipase D reaction was proportional to the enzyme concentration over the absorbance change range of 0 to 0.25 (equivalent to 0-21 micron of choline) under the optimal reaction conditions.

[Stimulating effect of glucagon and theophylline on the activity of rat liver betamine-homocysteine-methyltransferase. Role of cyclic adenosine-3',5'-monophosphate]

Effect of glucagon, theophylline, NaF and cyclic 3',5'-AMP on the activity of betaine-homocysteine-methyl transferase (BHMT) was studied in homogenates of rat liver tissue. Intraperitoneal administration of theophylline into adult rats increased the BHMT activity in liver tissue. After administration of theophylline the BHMT activity was distinctly increased in liver tissue within 2 hrs, approaching the maximal value within 3 hrs after which it decreased quickly up to 5-6 hrs. Intraperitoneal administration of glucagon into adult rats also increased the BHMT activity; theophylline, administered simultaneously with glucagon, potentiated the effect of the latter on the BHMT activity in liver tissue. Administration of glucagon into rat embryos 1-2 days before the birth was accompanied by a 2-fold increase in the BHMT activity. In the in vitro experiments theophylline (10(-6)-10(-5) M) showed the stimulating effect on the liver tissue BHMT activity. Dibutyryl adenosine-3,5'-cyclic phosphate and NaF caused the variable effect on the BHMT activity in liver tissue of adult rats. Administration of cyclic-3',5'-AMP (5 mg per 100 g of body weight) decreased the BHMT activity in liver tissue mitochondria and increased 2.5-fold the enzyme activity in cytosole.

Experimental allergic optic neuritis (EAON) in the rabbit. A new model to study primary demyelinating diseases

In New Zealand albino rabbits the axons of the nerve fibre layer are myelinated over a long distance within the retina. Primary demyelination of these fibres was induced by sensitization of the animals to bovine cerebral white matter or myelin basic protein in complete Freund's adjuvant and challenge thereafter by intravitreous injection of basic protein (BP) or purified tuberculin (PPD). Production of segmental demyelination as a result of sensitization to brain-specific antigen (BP) and indifferent (PPD) antigen, shows that morphologically the same type of lesions can be induced by any antigen which will elicit cell-mediated immune reaction.

Structure and conformation of bilirubin. Opposing views that invoke tautomeric equilibria, hydrogen bonding and a betaine may be reconciled by a single resonance hybrid

A novel conformational structure of bilirubin is presented which obtains maximum stabilization through a system of four intramolecular hydrogen bonds. Two hydrogen bonds link oxygen and nitrogen atoms of each end ring to the contralateral carboxyl group. The proposed structure can explain a variety of uncommon features of bilirubin, and reconciles many seemingly contradictory hypotheses by accommodating them in individual structures which are mesomeric forms of one resonance hybrid. In the light of this newly conceived structure the following characteristics of bilirubin are re-evaluated: the stability of the compound, its reaction with diazomethane, the conformational behaviour of its dimethyl ester, its spectral properties, the chirality of the compound when complexed to serum albumin, and the structure of its metal chelates.