What's new in lysozyme research?

The present review is focused on the main achievements realized in the lysozyme research field since the meeting held in 1972 to commemorate the fiftieth anniversary of the discovery of this enzyme. Despite of extensive structural, physico-chemical, crystallographic, genetic, immunological and evolutionary studies devoted to lysozymes, their biological role is still not exactly known.     

Characterization of the amino acids of bovine fibrinogen involved in the fibrinogen-thrombin interaction of the blood clotting process. Comparison with the milk clotting process

Summary Bovine fibrinogen and the A and B chains of bovine fibrinogen have been subjected to chemical modification by a number of reagents and the effects of these procedures on the susceptibility of the proteins to thrombin hydrolysis is described. The reagents used were rose bengal (for photo-oxidation), 2-hydroxy-5-nitrobenzyl bromide, N-acetylimidazole, iodoacetic acid and diethyl pyrocarbonate. Evidence is presented which indicates that the tryptophan and tyrosine residues of fibrinogen are not involved to any great extent in the interaction of this protein with thrombin. Modification with iodoacetic acid suggests that methionine residues play a major role in such interactions, but the fibrinogen chains on which the important residues reside remain uncertain. The use of diethyl pyrocarbonate indicates the participation also of histidine in fibrinogen-thrombin interactions and that, whereas the histidine residues of the B chain are involved to a great extent, it appears that those of the Aa chain are not. The similarities which exist between the fibrinogen-thrombin and the -casein-chymosin systems are discussed.Abbreviations used DEP diethyl pyrocarbonate (ethoxyformic anhydride) - HNBB 2-hydroxy-5-nitrobenzyl bromide - N-Acl N-acetylimidazole - PTC phenylthiocarbamyl - PTH 3-phenyl-2-thiohydantoin.     

Effect of the fungal toxin (zearalenone) on the reproductive system and fertility of male and female rats.

The fertility-inhibiting effects of long-term (8 weeks) consumption of maize infected with a fungus producing F2 toxin (zearalenone) was studied in adult male and female albino rats. The fertility rate was further decreased by 25-30% if the animals were kept on contaminated diet up to 14 weeks. The gonadal weight was decreased, follicular maturation and spermatogenesis were disturbed. The toxic diet consumed by mothers during pregnancy and lactation induced permanent changes in reproductive organs, disorders in vaginal cyclicity and disturbed fertility in the offspring. Neonatal administration of purified F2 toxin provoked similar changes. It is suggested that this fungal toxin may cause sterility syndrome in the offspring, similar to that produced by androgen or estrogen administration.     

Intravenous perfusion of adrenaline and adaptation to muscular exercise in man]

Eleven normal subjects underwent epinephrine perfusions (1.9; 6.1; 11.8 ng/min) during a short (20 min) and mild (50% VO2 max) exercise. VO2 was not modified by epinephrine perfusion, while heart rate ventrilation and plasmatic lactate were increased proportionally to epinephrine doses.     

Trophoblastin, an antiluteolytic protein present in early pregnancy in sheep.

Trophoblastin, an antiluteolytic component from the embryo, was identified in the ewe by the means of intrauterine injections of homogenates from trophoblasts at 14--16 days pregnancy. Homogenates from embryos and their membranes at 21--23 days pregnancy did not extend the life of the corpus luteum, suggesting that trophoblastin synthesis occurs for only a short period. The trophoblastin was thermolabile (80 degrees C for 30 min) and inactivated by pronase. Treatment of ewes with oCS, hCG, and extracts of 120-day placentae did not affect the time of luteolysis. The protein appears to be insoluble at pH 7 or 8, but to dissolve readily at pH 9.6. After injection of homogenates or extracts from 15--16-day-old trophoblasts, the initial CL were maintained for more than 1 month in most cyclic recipient ewes. Surgical removal of embryos at 21--23 days resulted in luteal maintenace for more than 1 month in over 50% of the operated animals. All the maintained CL were secretory although their average weight was about one-half of that CL of normal pregnancy, suggesting the existence of complementary luteotrophic placental factors. The uteri of most of these pseudopregnant ewes were distended with a clear, sterile fluid.     

A family with a satellited Yq chromosome

Summary A large pedigree with a satellited Yq chromosome is described, Q, C, and NOR banding were performed. Family C proband suffers from a Klinefelter syndrome.     

Growth and cell wall changes in rice coleoptiles

A fractionation of non-cellulosic sugars of Oryza sativa L. coleoptile cell walls was carried out and the composition of each fraction was studied during coleoptile growth.Percentages of fractions extracted with boiling water and with oxalate (pectic substances) were almost constant throughout development. An increase in the K II hemicellulosic fraction (extracted with 24% KOH) content, and a decrease in the K I hemicellulosic fraction (extracted with 10% KOH) were detected, when coleoptile growth finished.The percentage of glucose content in the K I hemicellulosic fraction was highest in young coleoptiles and lowest in old ones. Furthermore, a highly significant linear relationship between amounts of glucose and growth rate was obtained, while a inverse relationship between the amount of xylose and arabinose and growth rate was attained.Abreviations GLC gas liquid chromatography - IAA indole-3-acetic-acid - TFA trifluoroacetic acid - T_o minimum stress-relaxation time     

Effect of prostaglandins E1 and F2 alpha on neuromuscular transmission in the frog sartorius muscle.

End plate potentials (e.p.p.s.) and miniature end plate potentials (m.e.p.p.s.) were recorded intracellularly at the neuromuscular junction of the frog sartorius muscle. Addition of as little as 8.5 x10(-8)M PGE1 reduced the mean m.e.p.p. frequency. The mean amplitude of m.e.p.p.s was not changed, the mean amplitude of the e.p.p.s and the quantum content of the transmitter released by a nerve impulse was slightly reduced. A decrease in mean m.e.p.p. frequency was also seen in response to the administration of 8.5 x 10(-8)M PG2 alpha. The mean amplitude of e.p.p.s and m.e.p.p.s and the quantum content remained unchanged. The possible presynaptic mode of action of PGs in the preparation of discussed.