Adaptation to respiratory acidosis in the turtle bladder

The effect of in vivo respiratory acidosis for 4 and 48 hr was examined in the turtle bladder by placing turtles in hypercapnic chambers. Blood pH was significantly lowered and pCO2 was significantly elevated over control values both 4 and 48 hr, while blood bicarbonate was only increased after 48 hr. In vitro rates for H+ secretion determined by the reverse short-circuit current were significantly greater in bladders from 48 hr of respiratory acidosis than those of controls (27.3 +/- 2.7 vs 20.6 +/- 1.7 microA, P less than 0.05). In vitro rates for HCO3- secretion determined by pH stat were not altered. Fluorescence microscopy was used to study cell morphology. The number of carbonic anhydrase cells (corrected for the total number of cells) as determined by four different fluorescence stains (6-carboxyfluorescein, rhodamine 123, acridine orange, and 3,3'-diethyloxacarbocyaninine iodide) was increased both after 4 and 48 hr of respiratory acidosis. However, the number of HCO3(-)-secreting (beta subtype) carbonic anhydrase cells, determined by a probe for the anion exchanger, NBD-taurine, was not increased. In vitro 1% CO2 for 4 hr also resulted in an increase in H+ secretion and in the number of 6-carboxyfluorescein-positive cells, both of which could be blocked with SITS pretreatment. We conclude that CO2 changes the mucosal cells more toward the carbonic anhydrase phenotype, and that if NBD-taurine accurately identifies the beta cells, that the adaptation produces or recruits more alpha-carbonic anhydrase cells.     

Postanoxic recovery of spontaneously beating isolated atria: pH related role of adenylate kinase

The functional activity, adenine nucleotides, and creatine phosphate content of spontaneously beating isolated rabbit atria were measured prior to anoxia, after 1 hr anoxia, and at the end of 1 hr reoxygenation at pH 6.7 and 7.2 During anoxia at pH 7.2 there was 13.3% loss of adenine nucleotides pool, 35.2% loss of ATP, 36.2% increase in ADP, 200% increase in AMP, and a decrease to 8.8% of CP assayed to the beating atria in oxygen. At pH 6.7 there was almost the same decrease in CP, about 10% decrease in ATP, no change in total adenine nucleotides, no change in AMP and a higher increase in ADP (88.7%). The postanoxic recovery was much more complete when the pH was 6.7 during anoxia, and the first 40 min of reoxygenation. The extent of recovery of functional activity correlated well with the level of ATP in all cases not CP. Since the adenylate kinase and ATPase activity both decrease at acidic pH, their combined diminution would tend to preserve the adenine nucleotide pool and thus the better recovery at pH 6.7, because of a decrease in energy demand and unavailability of AMP for the degradation process. This study also supports the notion of compartmented adenine nucleotides connected by the creatine phosphate-creatine energy shuttle.     

Assessment of Fc (IgG) receptor function in adherent murine peritoneal macrophages using soluble model immune complexes

Fc (IgG) receptor function on thioglycolate-elicited adherent peritoneal macrophages from normal mice (C3H/HeN) and mice with abnormal activation of macrophages (C3H/HeJ) was studied. For this, soluble model immune complexes composed of five to six mouse anti-dinitrophenyl (DNP) IgG antibodies (heavy oligomers) were incubated with adherent macrophages cultured for either 2 or 48 hr. Cells from both strains bound similar amounts of oligomers at both 2 and 48 hr of culture (about 10⁶ IgG protomers/cell). Uptake of oligomers measured at 37 °C was also similar at 2 and 48 hr of culture. Endocytosis of oligomers occurred rapidly with about 50% of surface-bound complexes being internalized within 30 min, but there was no evidence for catabolism of the endocytosed material. There was a 50% decrease in the ability of macrophages to bind oligomers following a prior exposure to soluble complexes. Return to maximal binding after the preincubation with soluble complexes was incomplete for cells of both strains at both 2 and 48 hr of culture even after 2 hr at 37 °C.     

Changes in the activities of enzymes, especially lactate dehydrogenase, in endotoxin-poisoned mice.

Carbohydrate metabolic disorders were investigated by means of enzyme activities in mice (ddYS) injected intraperitoneally with endotoxin from Salmonella typhimurium. The mice exhibited hyperglycemia 2 hr after administration of endotoxin and hypoglycemia at 18 hr. Activity of hepatic phosphorylase in the endotoxin-poisoned mice at 2 hr was slightly higher than that in the control mice, whereas the level of this activity was not significantly different from that in the controls after 18 hr. Glucose-6-phosphatase activity in the poisoned mice increased by 2 hr after injection, but decreased by 18 hr. The blood lactate level in the poisoned mice transiently decreased until 3 hr after injection, but the mice exhibited a marked lactacidemia by 8–24 hr. The time course of lactate dehydrogenase (LDH) activity in various tissues was examined in mice injected with endotoxin. The activity of hepatic LDH declined to about two-thirds of that of the control mice after 16 hr, and was restored to the normal level by 48 hr. LDH in the cardiac muscle was markedly activated (by about 37%) in the early period (3–6 hr) after administration of endotoxin, and this activity gradually declined. However, the activity of LDH in the skeletal muscle showed a tendency similar to the rise and fall of the levels of blood lactate, and was restored to the normal value at 72 hr after injection. On the other hand, the serum LDH activity in the poisoned mice increased about 1.75-fold by 16 hr after injection. Mice injected with endotoxin exhibited a leakage of the isozymes LDH 3 and 5, but the origin of the leakage is uncertain. Similar elevation in the activities of transaminases (GPT and GOT) and malate dehydrogenase was found in the mouse serum at 16 hr after injection of endotoxin.     

AN AUTORADIOGRAPHIC STUDY OF THE 3H-URIDINE AND 3H-THYMIDINE INCORPORATION IN THE REGENERATING MOUSE LIVER

An autoradiographic study was made of the ³H-uridine incorporation into RNA and DNA in nucleus and cytoplasm of parenchymal cells in the regenerating liver of the mouse after a pulse time of 2 hr. After a decreased uptake of precursor into the parenchymal nucleus during the first 6 hr compared with the normal value, incorporation increased and was maximal at 36 hr; normal values were restored at 72 hr. The cytoplasmic labelling, after an initial small decrease, reached a maximum at 12 hr; this changed to normal 48 hr after hepatectomy. RNase-digestion of the liver sections left a small incorporation in both nucleus and cytoplasm: presumably DNA. This incorporation is maximal at 12 hr over the nucleus and at 24 hr over the cytoplasm. After a 2 hr pulse of ³H-thymidine, there was a marked uptake of the precursor into DNA about 24 hr after hepatectomy. This was maximal at 48 hr and reached normal values at 72 hr. A small amount of incorporation of ³H-thymidine into DNA was seen immediately after the operation, and this population of weakly labelled nuclei was still rather large 72 hr later.     

Cellular energy systems and reserpine ulcer in rats

Gastric ulcer was elicited in rats by reserpine (5 mg x kg-1 sc.) administration. Ulcer formation (number and severity) was measured 6, 12, 18 and 24 hr after reserpine administration. At the time of killing of the animals, tissue levels of adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP), cyclic adenosine monophosphate (cAMP) were measured enzymatically and by radioimmunoassay in the gastric fundal mucosa. The sum of ATP + ADP + AMP (adenylate pool) and the ratio of ATP x ADP-1 were calculated. It was found that (1) the tissue levels of ATP, AMP, cAMP, sum of ATP / ADP + AMP (adenylate pool) and ratio of ATP x ADP-1 increased significantly in the gastric fundal mucosa 6 hr after reserpine administration, thereafter these values decreased gradually and significantly; (2) the tissue level of ADP increased significantly in the gastric fundal mucosa 6 hr after reserpine administration, meanwhile its level increased significantly at 18 and 24 hr; (3) the value of energy charge (ATP + 0.5 ADP x ATP + ADP + AMP-1) remained unchanged; (4) the peaks of biochemical alterations in the gastric fundus mucosa preceded he appearance of ulcers. It was concluded that (1) reserpine ulcer appears after an active metabolic response in the rat gastric fundal mucosa; (2) hypoxaemic damage in the gastric fundal mucosa can be excluded as a possible underlying mechanism of ulcer formation produced by reserpine administration; (3) before the appearance of reserpine ulcer, significant changes in the feedback mechanism, system, i.e. between the ATP--membrane ATPase--ADP and the ATP--adenylate cyclase--cAMP energy systems, can be observed in the rat gastric fundal mucosa.     

A review of 126 Caesarean sections by blood gas and the acid-base status of newborn calves

Blood gas and acid-base status was determined in 126 Caesarean-derived calves. The newborn calves were assigned by venous blood pH value at birth to three groups as follows: Group 1 (normal): pH above 7.2; Group 2 (slight acidosis): pH 7.2 to 7.0; and Group 3 (severe acidosis): pH below 7.0. Following Caesarean section births 80 (63.5%) calves had normal acid-base values, while 30 (23.8%) had a slight acidosis, and 16 (12.7%) had severe acidosis. The degree of hypoxia was similar in each group. Six calves (37.5%) in Group 3 died within 48 h of birth. The blood gas and acid-base status of Caesarean-derived. calves was not significantly influenced by any examined parameters with the exception of sex in Groups 1 and 2. The occurrence of meconium-stained calves was 9.1% (n = 11), and only two calves were slightly or severely acidotic immediately after birth.     

Action of shear on enzymes: studies with alcohol dehydrogenase.

Yeast alcohol dehydrogenase (ADH) solutions (approximately 1 mg/ml, pH 7) were sheared in a coaxial cylindrical viscometer. This was fitted with a lid sealing the contents from the atmosphere and preventing evaporation. At 30 degrees C after a total of 5 hr intermittent shearing at 683 sec-1 no losses of activity were observed. No losses were found after 5 hr continuous shearing and in a no-shear control. At 40 degrees C and 683 sec-1 there were only small activity losses in 5 hr. Shearing at 3440 sec-1 no measurable losses of activity were found with a 1.03 mg/ml solution in 5 hr at 30 degrees C, a 1.03 mg/ml solution in 8 hr at 5 degrees C, and with a 3.89 mg/ml solution in 3 hr at 5 degrees C. In all these cases, however, a white precipitate formed that was not observed in zero shear control experiments. The sheared 3.89 mg/ml solution was clarified by centrifugation. It was shown that there were no ADH aggregates in the supernatant and that the precipitate was less than 2% of the original protein. At 30 degrees C under adverse pH conditions (pH 8.8) there was no significant difference in activity losses of an approximately 1 mg/ml solution sheared at 65 and 744 sec-1. An approximately 0.5 mg/ml ADH solution, pH 7, was agitated in a small reactor with no free air-liquid interface. Peak shear rates near the impeller were estimated to be about 9000 sec-1. Only a small decrease in specific activity was observed until over 15 hr total running at 5 degrees C.     

Effects of fructose on the energy metabolism and acid-base status of the perfused starved-rat liver. A 31phosphorus nuclear magnetic resonance study.

Fructose metabolism has been studied with 31P n.m.r. in perfused livers from rats starved for 48h. The time course of changes in liver ATP, Pi and sugar phosphate (fructose l-phosphate) concentrations, and intracellular pH were followed in each perfusion after infusion of fructose to give an initial concentration of either 5mM or 10mM. Rapid falls in the concentrations of ATP and Pi and intracellular pH occurred after infusion of fructose, reaching a minimum after 4-5 min, which was lower in the 10mM group than in the 5mM group. These changes were accompanied by a rapid rise in fructose 1-phosphate, reaching a plateau also after 4-5 min. At both concentrations of fructose, after the early falls, some recovery of ATP, Pi and intracellular pH occurred; this was complete for Pi and intracellular pH in the 5mM-fructose experiments (within 12-30 min). Complete restoration of ATP to the pre-fructose value was not achieved in either the 5mM of 10mM groups. Measurements of the uptake of lactate by the liver indicated that the fall in intracellular pH was caused primarily by production of protons accompanying the formation of lactate from fructose with possibly a transient contribution generated during the rise in fructose 1-phosphate.     

Recovery of mitochondrial function and endogenous antioxidant systems in vitrified bovine oocytes during extended in vitro culture

This study was designed to examine the recovery of mitochondrial function and endogenous antioxidant systems in vitrified oocytes during extended incubations. After 16 hr of in vitro maturation, bovine meiosis‐II oocytes were vitrified, and then surviving oocytes were cultured an additional 8 hr. ATP content, ATP synthase activity, expression of ATP synthase F0 subunit 6 (ATP6) and 8 (ATP8) genes, and reactive oxygen species (ROS) levels were investigated in the vitrified oocytes during this additional period (4 or 8 hr). The results showed that: (1) the ATP content and ATP synthase activities in vitrified oocytes at 8 hr post‐warming (754.6 fmol, 25.9 nmol NADH/min/mg) were significantly higher than in oocytes immediately warmed (568.3 fmol, 8.7 nmol NADH/min/mg), but still lower than in control oocytes (901.5 fmol, 30.7 nmol NADH/min/mg); (2) the relative expression of ATP6 and ATP8 was initially down‐regulated in oocytes when they were first warmed, increased by 4 hr post‐warming, and were again down‐regulated by 8 hr post‐warming; (3) ROS levels in oocytes at 0, 4, and 8 hr post‐warming were significantly higher than in control oocytes; and (4) after parthenogenetic activation, the blastocyst rate of oocytes at 8 hr post‐warming (26.7%) was significantly higher than that of oocytes immediately warmed (16.9%). These results indicated that mitochondrial function and endogenous antioxidant systems recovered significantly better in vitrified–thawed bovine oocytes with 8 hr of additional incubation, but they did not achieve the activity levels found in fresh oocytes. Mol. Reprod. Dev. 78:942–950, 2011. © 2011 Wiley Periodicals, Inc.     

Nicotinamide–adenine dinucleotides in acute liver injury induced by ethionine, and a comparison with the effects of salicylate

1. The effects of single doses of ethionine or sodium salicylate on the nicotinamide-adenine dinucleotide content of rat liver have been studied. 2. There was no significant change in the sum of NAD+NADH(2) during the early period (0-2hr.) of the liver injury induced by ethionine but there was a decrease in this value of approx. 30% by 4hr. after administration. 3. Ethionine had no significant effect on the NADP+NADPH(2) during the first 2hr. period after administration. The sum then decreased to a value approx. 70% of the control by 3hr. after dosing but showed a partial recovery at the 4hr. period before decreasing again in later stages of the poisoning. 4. Salicylate produced a very rapid decrease in the NADP+NADPH(2) in the liver after intraperitoneal injection. After 1hr. the decrease was approx. 30% of the initial value; the sum slowly returned towards the normal range during the following 4hr. 5. A high parenteral dose of salicylate was found to cause only a small depression in the concentration of ATP in rat liver in contrast with the rapid depletion produced by ethionine. 6. These results are discussed in terms of the liver disturbances produced by ethionine and salicylate.     

Isolation and Restriction Mapping of a Pseudomonas Plasmid

The effects of the injection of a large amount of N¹ -methylnicotinamide (MNA) (500 mg per kg body weight) on the ratio of N¹ -methyl-4-pyridone-3-carboxamide (4-py) to N¹ -methyl-2-pyridone-5- carboxamide (2-py) excretion, and the activities of 2-py and 4-py forming MNA oxidases were investigated in rats. The injected MN A was excreted very rapidly into the urine; 46 % of the dose was excreted from 0~3hr post-injection, 15% from 3~6hr, 6% from 6~9hr and 1.5% from 9~ 12hr. The ratio of 4-py to 2-py also decreased rapidly; the ratio being about 0.6, 0.4, 0.4 and 0.6 from 0~3hr, 3~6hr, 6~9hr and 9~ 12hr post-injection, respectively. This ratio then recovered rapidly; being about 2, 5.5, 8.5 and 9.7 from 12~24 hr, 24 ~48 hr, 48~72 hr and 72 ~96 hr post-injection, respectively. The normal range of 4-py to 2-py excretion ratio is 8~14. So, this ratio returned to a normal level by day 3 post-injection. The rats were killed 5 hr after the MNA injection. At this time (the lowest ratio was observed around this time), the activities of 2-py and 4-py forming MNA oxidases in the injected group were 59 % and 11 % of the normal levels, respectively. Therefore, it was found that the decreased ratio of 4-py to 2-py excretion with the MNA injection was mainly due to the higher inhibition of the 4-py forming MNA oxidase than of the 2-py forming MNA oxidase by the MNA injection.     

Studies on Changes of Protein by Dye Sensitized Photooxidation

Physico chemical changes of ovalbumin illuminatied in the presence of methylene blue were examined. Solubility of ovalbumin was remarkably reduced, but its extents were varied with the value of pH, that of ionic strength and illumination time. Illumination brought about aggregation of protein molecules which was revealed on the ultra centrifugal patterns. Electrophoretical patterns showed that three peaks characteristic of native ovalbumin went into one peak after 24 hr and into two peaks after 48 hr. After an illumination for 6 hr, titration curves showed that bound protons decreased below pH 8.0 and increased over pH 8.0. The spectra of illuminated ovalbumin were displaced upward and the absorption maximum shifted toward the longer region of wave length.     

EARLY AND LATE INCORPORATION OF TRITIATED THYMIDINE INTO SKIN CELLS AND THE PRESENCE OF A LONG-LIVED G0-SPECIFIC PRECURSOR POOL

40 min after a single injection of 50 µCi of tritiated thymidine a 3 mm punch of DBA-1 mouse skin contains about 1000 dpm. This value remains constant for at least 48 hr after injection. 50 hair follicles contain about 40 dpm, and from these values the activity calculated to reside in the basal layer of a 3 mm punch of skin is 760 dpm. These values also remain constant with time after injection. Fresh punches of skin contain much more activity. The fixative-soluble fraction (the difference between fresh and fixed values) decays slowly with time. The values for DBA-2 mice are similar. Plucking the hair from the follicles appears immediately to increase the size of the fixative-soluble fraction and decrease the fixed tissue values to about 500 dpm per punch for whole skin and about 1 dpm per 50 follicles for DBA-1. Thus almost all the activity is restricted to the epidermis. The fixative-soluble fraction returns approximately to the unplucked value between 24 and 48 hr after plucking. However, during this period the fixed tissue values are rising rapidly as stimulated cells enter S. It appears that in both strains labeled material remains available for incorporation into stimulated cells for at least 48 hr after a single injection. The amount persisting appears to decrease with time. The whole-fixed skin, the hair follicles, and the epidermis all contain cells that are capable of becoming labeled after stimulation 8–48 hr after an injection. The label in question does not become incorporated into normal cycling skin or hair follicle cells. It is concluded that the DNA precursor pool is possibly connected with G₀ cells and that both the hair follicle and the basal layer of the epidermis contain these resting cells.     

pH-dependent effects of Cr(NH3)2ATP on kinetics of yeast hexokinase PII. Relationship to the slow transition mechanism.

The effect of Cr(NH3)2ATP, a virtually inert, inner sphere metal-ligand complex, on the kinetics of purified yeast hexokinase PII has been studied at pH 6.5 and pH 7.5. At pH 6.5, where the normal assays exhibit a slow burst-type transient, low concentrations of Cr(NH3)2ATP were found to activate both phii, the initial velocity, and phiII, the steady state velocity. At higher concentrations, Cr(NH3)2ATP was found to be a competitive inhibitor versus MgATP for both phii and phiII. The apparent Ki values for both velocities were the same. The inhibition by Cr(NH3)2ATP at pH 6.5 was found to be a slow process with half-times similar to those found for the normal burst-type transient at this pH value. At pH 7.5, where normal assays exhibit linear progress curves, Cr(NH3)2ATP behaved similarly to that observed before at pH 7 (Danenberg, D. D., and Cleland, W. W. (1975) Biochemistry 14, 28-39), i.e. it was a competitive inhibitor versus MgATP and it caused a slowing of the reaction rate over the first several minutes. The apparent Ki for the initial velocity was 8-fold higher than the apparent Ki for the steady state velocity, suggesting tighter binding of Cr(NH3)2ATP with time. Preincubation experiments indicated that the normal pH 6.5 burst-type transient could be eliminated by appropriate preincubation with Cr(NH3)2ATP and a sugar. In agreement with Danenberg and Cleland (1975), similar preincubations have been shown to produce linear assays at pH 7.5 in the presence of Cr(NH3)2ATP. Similar results were seen with MgITP as the nucleotide substrate, where a burst-type transient is not seen at either pH value under normal assay conditions. At pH 7.5, a slow decrease in the reaction rate is seen over the first several minutes in the presence of Cr(NH3)2ATP. The apparent Ki for phii was 7-fold higher than the apparent Ki value for phiII, again suggesting a tighter binding of Cr(NH3)2ATP with time. A similar observation was made at pH 6.5, but the Ki values for phii and phiII were the same, suggesting no tightening of the binding of Cr(NH3)2ATP with time at this pH value. These results suggested that both slow processes reflect the same basic molecular change, but the consequences are different at the two pH values, presumably because of the difference in the charge of the enzyme. The Cr(NH3)2ATP kinetics at pH 6.5 have been interpreted in terms of a modification of the slow transition mechanism for hexokinase (Shill, J. P., and Neet, K. E. (1975) J. Biol. Chem. 250, 2259-2268). It is postulated that glucose and Cr(NH3)2ATP induce the same slow conformational change at pH 6.5 as that induced by glucose and MgATP, which gives rise to the normal burst-type transient. This suggests that Cr(NH3)2ATP may be a useful tool for physical studies to determine the cause of the slow transition of yeast hexokinase. Activation by low concentrations of Cr(NH3)2ATP was interpreted as binding of the nucleotide to an activator site on the enzyme, causing a shift in the distribution of enzyme towards the more active form.     

Some properties of the pyruvate carboxylase from Pseudomonas fluorescens.

The pyruvate carboxylase of Pseudonomas fluorescens was purified 160-fold from cells grown on glucose at 20 degrees C. The activity of this purified enzyme was not affected by acetyl-coenzyme A or L-aspartate, but was strongly inhibited by ADP, which was competitive towards ATP. Pyruvate gave a broken double reciprocal plot, from which two apparent Km values could be determined, namely 0-08 and 0-21 mM, from the lower and the higher concentration ranges, respectively. The apparent Km for HCO3 at pH 6-9, in the presence of the manganese ATP ion (MnATP2-), was 3-1 mM. The enzyme reaction had an optimum pH value of 7-1 or 9-0 depending on the use of MnATP2- or MgATP2-, respectively, as substrate. Free Mg2+ was an activator at pH values below 9-0. The enzyme was strongly activated by monovalent cations; NH4+ and K+ were the better activators, with apparent Ka values of 0-7 and 1-6 mM, respectively. Partially purified enzymes from cells grown on glucose at 1 or 20 degrees C had the same properties, including the thermal stability. In both cases 50% of the enzyme activity was lost after pre-incubation for 10 min at 46 degrees C. The molecular weight was estimated to be about 300000 daltons by gel filtration on Sephadex G-200. The regulatory properties and molecular weight are thus similar to those determined for the pyruvate carboxylases from Pseudomonas citronellolis and Azotobacter vinelandii.     

Inhibition by ATP and activation by ADP in the regulation of flagellar movement in sea urchin sperm

ATP and ADP are known to play inhibitory and activating roles, respectively, in the regulation of dynein motile activity of flagella. To elucidate how these nucleotide functions are related to the regulation of normal flagellar beating, we examined their effects on the motility of reactivated sea urchin sperm flagella at low pH. At pH 7.0-7.2 which is lower than the physiological pH of 8, about 90% of reactivated flagella were motionless at 1 mM ATP, while about 60% were motile at 0.02 mM ATP. The motionless flagella at 1 mM ATP maintained a single large bend or an S-shaped bend, indicating formation of dynein crossbridges in the axoneme. The ATP-dependent inhibition of flagellar movement was released by ADP, and was absent in outer arm-depleted flagella. Similar inhibition was also observed at 0.02 mM ATP when demembranated flagella were reactivated in the presence of Li+ or pretreated with protein phosphatase 1 (PP1). ADP also released this type of ATP-inhibition. In PP1-pretreated axonemes the binding of a fluorescent analogue of ADP to dynein decreased. Under elastase-treatment at pH 8.0, the beating of demembranated flagella at 1 mM ATP and 0.02 mM ATP lasted for approximately 100 and 45 s, respectively. The duration of beating at 0.02 mM ATP was prolonged by Li+, and that at 1 mM ATP was shortened by removal of outer arms. These results indicate that the regulation of on/off switching of dynein motile activity of flagella involves ATP-induced inhibition and ADP-induced activation, probably through phosphorylation/dephosphorylation of outer arm-linked protein(s).     

The effect of controlled atmospheres on carbohydrate metabolism in the tissue of Ephestia cautella (walker) pupae

Ephestia cautella pupae, 0–24 hr old, were exposed for 24 hr to a controlled atmosphere, either high in carbon dioxide or low in oxygen at 26°C. Tissue levels of glycogen, trehalose, glucose, α-glycerophosphate, glycerol, lactate, alanine, ATP, ADP, AMP, citrate and malate were determined in exposed pupae. Hypercarbia tended to increase the consumption of glycogen but had no clear effect on trehalose consumption. Glucose levels were similar to insect exposed to normal and to hypercarbic atmospheres but significantly higher in insects exposed to hypoxia. α-Glycerphosphate, glycerol, lactate and alanine levels were high in 0–24 hr old pupae but fell after 24 hr exposure to normal of hypoxic atmospheres. The levels of these metabolites fell less when nitrogen was replaced by carbon dioxide. Hypercarbia reduced the total amount of adenine nucleotides and the energy charge. However, 1% oxygen in nitrogen markedly affected the ATP level. Citrate was reduced in hypercarbia and in hypoxia, whereas malate was reduced by hypercarbia but increased in hypoxia.     

On Food Vacuoles in Tetrahymena pyriformis GL

SYNOPSIS. The following problems concerning food vacuoles were studied by in vivo observations of Tetrahymena: (A) Formation of food vacuoles . The process may be divided into 4 stages. Stage 1—gradual growth of the limiting membrane of the open food vacuole (of short duration). Stage 2—"filling up" of the fully expanded vacuole (of long duration). Stage 3—"closing off" of the vacuole (of brief duration). Stage 4—initial movement of the detached vacuole away from the cy-tostome. The possible role of the oral components (apart from membranellar beating) in the process is discussed. (B) Change of pH in the food vacuole . After ingestion of heat-killed yeast stained with indicator dyes (neutral red, bromcresol purple, bromcresol green, bromphenol blue), the observed color changes indicate that pH is neutral in the forming vacuole as well as in newly formed vacuoles; that a pH value of 6.0–5.5 is reached after ∼ 5 min; and that the lowest pH value between 4.0 and 3.5 is reached after 1 hr. Before egestion the pH again increases. (C) Length of the digestive cycle . A determination of the time required to deplete the cells of labeled vacuoles formed during a short exposure, was attempted. Defecation was observed after 1/2 hr and it was frequent after 2 hr. About 25% and 50% of the labeled vacuoles were removed after 1 hr and 2 hr, respectively; however, labeled vacuoles may still be seen in some cells 6 hr after ingestion. The conclusion is that the digestive cycle lasts ∼ 2 hr and that egestion of undigestible material is a random process.     

Studies of the effect of experimental inflammation on rat liver nucleotide sugar pools

The effect of experimental inflammation on levels of nucleotide sugars was studied in rat liver. There was an increase of about 2-fold in the levels of UDP-N-acetylhexosamines and GDP-Man at 8 and 4 hr after inflammation, respectively. At 48 hr after inflammation GDP-Man had returned close to control values, but UDP-N-acetylhexosamines were still about 50% above controls. There was a 30% reduction in CMP-NeuAc and UDP-Gal at 8-12 hr after inflammation before increasing to slightly above controls at 16-48 hr after inflammation. Inflammation resulted in an increase in activities of glucosamine-6-phosphate synthase and UDP-GlcNAc-2'-epimerase to about twice control activities at 24 and 8 hr after inflammation, respectively, before declining; CMP-NeuAc synthase activities did not show large changes following inflammation.