Osmotic characteristics of sheep and cattle embryos

Ten minutes of exposure to increasing concentrations of sucrose caused a proportional decrease in the volume of sheep late morulae, their relative volume changed as a linear function of the reciprocal of the osmolality of the medium. Day 6 sheep and Day 7 cattle embryos responded to the addition of permeating cryoprotectants by an initial shrinkage which was followed by gradual reexpansion. After 1.25 min exposure the relative volumes of sheep and cattle embryos respectively were 20 and 25% smaller in glycerol than in ethylene glycol. The volumes of cattle and sheep embryos remained smaller in glycerol than in ethylene glycol up to the final observation at 30 min. The osmotic response of sheep late morulae to 2.0 M propylene glycol was intermediate between their response to 2.0 M glycerol and to 2.0 M ethylene glycol. These results indicate that Day 6 sheep and Day 7 cattle embryos are more permeable to ethylene glycol than to glycerol.     

Cellular regulation of ADP-ribosylation of proteins. III. Selective augmentation of in vitro ADP-ribosylation of histone H3 in murine thymic cells after in vivo emetine treatment

Thymic cells were isolated at intervals of between 0 and 144 h from mice that received one intraperitoneal injection of emetine (33 mg/kg), and thymus weight, incorporation of [14C]leucine into proteins and [3H]thymidine into DNA in intact thymic cells, as well as initial rates of protein ADP-ribosylation in permeabilized cells [A. Sóoki-Tóth, F. Asghari, E. Kirsten, and E. Kun (1987) Exp. Cell Res. 170, 93] were simultaneously monitored. The effect of emetine as an inhibitor of protein synthesis [F. Antoni, N. G. Luat, I. Csuka, I. Oláh, A. Sóoki-Tóth, and G. Bánfalvi (1987) Int. J. Immunopharmacol. 9, 333] corresponds to the induction of sequential cellular events, such as cell exit and remigration, by other antimitotic agents [C. Penit and F. Vasseur (1988) J. Immunol. 140, 3315] and produces an activation of proliferation of cells reentering into this organ. Proliferation, as demonstrated by a large increase in DNA synthesis and entrance into S phase, was kinetically related to an apparent increase in poly(ADP-ribose) polymerase activity in thymic cells and a highly significant in vitro ADP-ribosylation of histone H3. Since no DNA fragmentation occurred in thymic cells, as tested by a fluorometric technique [C. Birnboim and J. J. Jevac (1981) Cancer Res. 41, 1889], it is probable that a selective activation of poly(ADP-ribose) polymerase may have been induced in cells that undergo differentiation and proliferation while repopulating the thymus.     

No effect of isolation on blood pressure and daily electrolyte excretion in rats

The effects of isolation stress on mean blood pressure (BP) and on body weight, water and food intake as well as on urine flow, urinary sodium and potassium excretion were studied in CFY and Long Evans rats. During a 7 day isolation period, food and water intake as well as urine flow, urinary sodium and potassium excretion, as expressed for 100 g body weight, were not changed in either group. Body weight increased similarly in isolated (38 +/- 2 g) and aggregated (41 +/- 5 g) CFY rats. Compared to group housed rats, BP in male CFY animals was not increased after a 7 day isolation (111 +/- 3 vs 111 +/- 3 mmHg, NS). In additional experiments high sodium intake by physiological saline drinking slightly elevated blood pressure but failed to induce arterial hypertension in isolated rats (118 +/- 2 vs 121 +/- 3 mmHg, NS). We conclude that, contrary to some reports from other laboratories, isolation stress has no detectable effect on BP and/or water and electrolyte balance.     

Specific inhibition of human granulocyte elastase with peptide aldehydes

The kinetic features of human granulocyte elastase, chymotrypsin, porcine pancreatic elastase and elastomucoproteinase were compared. Amino acyl ester substrates were assayed and Km and kcat values were defined. Aldehyde analogues of the p-nitroanilide substrates designed for granulocyte elastase as optimal for Km appeared to be potent inhibitors. Suc-D-Phe-Pro-valinal (Ki = 40 microM) was found to inhibit granulocyte elastase competitively and specifically when measured with synthetic substrates, and the Ki was 3 microM with the natural protein substrate, elastin.     

Sucrose dilution of glycerol from mouse embryos frozen rapidly in liquid nitrogen vapour

The toxic effects of sucrose and the conditions of in-straw glycerol removal after freezing and thawing were studied using Day-3 mouse embryos. At 20 degrees C, exposure to less than or equal to 1.0 M-sucrose for periods up to 30 min had no adverse effects on freshly collected embryos. At 25 and 36 degrees C, however, greater than or equal to 1.0 M-sucrose significantly reduced the developmental potential (P less than 0.001). In the freezing experiments the embryos were placed in 0.5 ml straws containing 40 microliters freezing medium separated by an air bubble from 440 microliters sucrose solution. The straws were frozen rapidly in the vapour about 1 cm above the surface of liquid nitrogen. The post-thaw viability was substantially better after sucrose dilution at 20 degrees C than at 36 degrees C. Mixing the freezing medium with the sucrose diluent immediately after thawing further improved the rate of survival relative to mixing just before freezing (P less than 0.001). The best survival was obtained when the freezing medium contained 3.0 M-glycerol + 0.25 M-sucrose; it was mixed with the diluent after thawing and the glycerol was removed at 20 degrees C. Under such conditions the sucrose concentration in the diluent had no significant effect on the rate of development (0.5 M, 69%; 1.0 M, 73%; 1.5 M, 64%). The results show that during sucrose dilution the temperature should be strictly controlled and suggest that intracellular and extracellular concentrations of glycerol are important in the cryoprotection of embryos.     

Role of equilibration before rapid freezing of mouse embryos

The time requirements for permeation by glycerol and dehydration by sucrose before rapid freezing of Day-3 mouse embryos by direct transfer to -180 degrees C were studied. When the embryos were equilibrated in 2.0, 3.0, or 4.0 M-glycerol + 0.25 M-sucrose for 2.5 to 40 min, the post-thaw viability increased (P less than 0.001) with the length of equilibration period at 4 degrees C. At 20 degrees C the volume of embryos increased with the duration of equilibration up to 20 min (P less than 0.001), but the post-thaw viability was not affected. The effect of equilibration in glycerol-sucrose was determined at 20 degrees C for embryos which were previously permeated by glycerol, dehydrated by sucrose or left in PBS + 5% FCS. The survival of previously permeated embryos was not affected by equilibration for 1-16 min in glycerol-sucrose. The maximum survival rate was attained after shorter equilibration in glycerol-sucrose for embryos without pretreatment (4 min) than for those previously dehydrated (8 min). It is concluded that increases in the intracellular glycerol level are beneficial for the viability of rapidly frozen mouse embryos and previous or concomitant exposure to sucrose unfavourably affects glycerol permeation.     

EUF-nutrient contents required for optimal nutrition of grapes

Summary Our field surveys conducted in 10 Hungarian grape producing areas have revealed that the nutrient contents of vine leaves of different grape varieties were closely correlated with the EUF-nutrient contents of different soil types with different contents of clay. Resulting from these relationships the following EUF-nutrient values are considered as required for optimal nutrition of the vine-stock to attain grape yields of 10–12 t/ha in the areas under investigation:     

Time course of denervation diuresis and natriuresis in the anaesthetized rat

The effect of unilateral renal sympathectomy on renal excretion of water and sodium was studied in three groups of Inactin-anaesthetized rats: 1-3, 4-19, and 20-35 weeks after denervation. Increased sodium excretion from the denervated kidney in the absence of changes in GFR was observed up to 35 weeks following renal denervation. Thus, in a functional sense, renal reinnervation may have only been partial during the time interval studied.