Renal excretion of urea in response to changes in nitrogen intake in desert (black Bedouin) and non-desert (Swiss Saanen) goats

• 1.1. Renal responses were compared between desert (black Bedouin) and non-desert (Swiss Saanen) goats fed (a) Lucerne hay ad. lib., (b) Lucerne hay restricted to 65% of the ad. lib. consumption and (c) wheat straw.
• 2.2. Reduced feeding in both breeds resulted in proportional reduction in glomerular filtration rate (GFR) and the amount of urea excreted with no change in the percentage of urea reabsorbed.
• 3.3. In both breeds appreciably less urea was filtered at the glomerulus when a low-nitrogen diet was fed compared with a high nitrogen diet and the percentage of filtered urea reabsorbed increased from about 55 to about 90%.
• 4.4. In both breeds the reduction in GFR is quantitatively more important than the increase in the percentage of filtered urea reabsorbed in regard to renal urea conservation.
• 5.5. The results indicate no qualitative differences between desert and non-desert breeds of goat. The advantages of the Bedouin over the Saanen goats is related to the lower GFR values in the Bedouin goat and mainly their ability to reduce its GFR much more than the Saanen goats in response to lower nitrogen intake.

     

Changes in body composition of germ-free and conventional chickens during starvation

• 1.1. Changes in body composition during starvation were compared between germ-free (GF) and conventionalized (CVL) chicks in experiment 1. At 8 days of age, the GF birds were divided into two groups, i.e. GF and CVL groups. The CVL birds were inoculated with faeces from conventionally reared birds. Until 14 days of age, both birds were fed a diet ad lib, and thereafter starved for 6 days.
• 2.2. Nitrogen loss during starvation was significantly lower in CVL birds, though the reverse was true for water loss. Fasting heat production was comparable between two environments.
• 3.3. Influence of the gut microflora on body weight and nitrogen losses during starvation was investigated in birds prefed diets high or low in dietary protein in experiment 2.
• 4.4. No significant effect of the gut microflora was observed in body weight and nitrogen losses. Body weight was severely reduced in birds prefed the high protein diet and nitrogen loss was lower in birds prefed the low protein diet.

     

Effect of diet and essential amino acids gavage on young rat amino acid metabolism enzymes

• 1.1. The effects of a high-fat, high-energy diet and essential plus semi-essential amino acid gavage on pup rats have been studied (60–65 animals).
• 2.2. The activities of alanine transaminase, adenylate deaminase, glutamine synthetase and serine dehydratase have been tested in liver and muscle.
• 3.3. Plasma was used for the estimation of proteins, urea, amino acids, glucose, lactate, 3-hydroxy-butyrate and acetoacetate.
• 4.4. Liver and muscle glutamine synthetase activities are increased by diet and gavage administered. Hepatic serine dehydratase is inhibited by a cafeteria diet but activated by amino acid gavage. Adenylate deaminase is inhibited by diet and gavage in the liver, but gavage does not affect this enzyme activity in muscle. Liver alanine transaminase is increased by the diet; in the muscle, cafeteria diet and amino acid gavage showed the highest values for this enzyme.
• 5.5. In the plasma, the increase in lactate produced by the diet is inhibited by the amino acids provided. Cafeteria-fed pups showed lower urea levels and higher 3-hydroxybutyrate concentrations in the plasma.
• 6.6. Intracellular glucose is diminished by cafeteria diet. In contrast, the blood cell amino acid concentration increases with diet and gavage supplied.

     

Urea excretion rates and waste nitrogen concentrations during metamorphosis of Xenopus laevis Daudin

• 1.1. Serum urea, ammonia concentrations in the blood and excretion were measured in tadpoles of different stages and juveniles of Xenopus laevis.
• 2.2. The urea excretion rate was determined with the help of injected ¹⁴C-urea.
• 3.3. Urea concentrations are higher during metamorphic climax and at the end of metamorphosis than during prometamorphosis.
• 4.4. Blood ammonia levels remain rather constant throughout metamorphosis.
• 5.5. Coincidentally, the relative amount of urea in the blood increases.
• 6.6. The ¹⁴C-urea excretion rates slow down from very high values (48%/hr) at the beginning of prometamorphosis to low rates (5%/hr) in newly metamorphosed animals.
• 7.7. This means that during metamorphosis not only is the possibility of urea production established. but there is a capacity to retard and store urea to some extent.

     

Effects of a purine inhibitor,allopurinol, on urate metabolism in the german cockroach,Blattella germanica L. (Dictyoptera: Blattellidae)

• 1.1. Adult male and female cockroaches (Blattella germanica) were maintained on a positive nitrogen balance diet (66% protein) containing various levels of allopurinol (0–3%) to determine the effects of allopurinol on urate synthesis and storage.
• 2.2. Each insect was injected with [¹⁴C]hypoxanthine and after 1 week was analyzed for whole-body hypoxanthine, xanthine and urate radiolabel.
• 3.3. There was a general trend of decreased whole-body radiolabel retention, radiolabeled body urates and total-body urate content in both sexes with increasing amounts of dietary allopurinol.
• 4.4. Virgin female adults were allowed to feed on diets containing 0, 25 and 66% protein plus 0.1% allopurinol and were injected with [¹⁴C]xanthine.
• 5.5. After 1 week radiolabel content in the whole-body xanthine and urate pools was determined.
• 6.6. Females on the 0% protein diets contained less radiolabel in the whole-body and body urates than those on either 25 or 66% protein diets.

     

Serum and urine biochemical indicators of nutritional status in adult female collared peccaries,Tayassu tajacu (tayassuidae)

• 1.1. Physiological responses of 13 adult female collared peccaries (Tayassu tajacu) to high quality and low quality diets, fed for 15 weeks, were examined. The low quality diet simulated energy and protein intake of peccaries during poor range conditions resulting from drought. Blood samples were collected after 10 and 15 weeks of dietary treatment; urine samples were collected after 15 weeks of treatment.
• 2.2. Females receiving the low quality diet for 15 weeks lost 27.4% of their original body weight, compared to no weight change among high quality-fed females.
• 3.3. Red blood cell counts, hematocrits, and hemoglobin concentrations were significantly greater among females fed a high quality diet compared to those receiving a low quality diet. High quality-fed females also had a higher mean corpuscular hemoglobin concentration. Plasma fibrinogen concentration was nearly twice as great among females receiving the low quality diet compared to the high quality group.
• 4.4. Consumption of the low quality diet resulted in significantly elevated serum levels of nonesterified fatty acids, alkaline phosphatase, phosphorus, alpha-2 globulin and alpha globulin: beta globulin ratio.
• 5.5. Consumption of the low quality diet resulted in significantly lowered serum levels of urea nitrogen, calcium, zinc, calcium: phosphorus, urea index, beta-1 flobulin, beta globulin: albumin ratio, thyroxine and triiodothyronine.
• 6.6. Serum levels ofcreatinine, total bilirubin, glucose, cholesterol, gamma glutamyltransferase, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, potassium, copper, magnesium, sodium chloride, total protein and gamma globulin were unaffected by diet quality.
• 7.7. Urine chemistry results suggested pH, osmolarity, albumin, creatinine phosphokinase, calcium and phosphorus concentrations might be useful indices for assessing nutritional status in female peccaries.

     

Specific dynamic action (SDA) in the supralittoral isopod,Ligia pallasii: Identification of components of apparent SDA and effects of dietary amino acid quality and content on SDA

• 1.1. Specific Dynamic Action (SDA) effects of diet were investigated in the supralittoral isopod, Ligia pallasii, using defined chemical diets.
• 2.2. “Apparent SDA”, or the total rise in metabolic rate following a meal, was resolved in animals eating a nutritionally complete chemical diet into three components: 8% mechanical costs of moving food through the gut, 40% “excitement costs” due to investigator disturbance and presence of food, and 52% SDA.
• 3.3. Excitement costs in animals exposed to food but which chose not to eat showed non-significant variation between diets containing different levels of chemical nutrients, but were significantly less on a diet containing only cellulose and agar.
• 4.4. SDA increased with increasing concentration of amino acids in the diet.
• 5.5. Substitution of whole-protein casein for free amino acids in the diet had no significant SDA effect, while substitution of free amino acids in the ratio found in casein more than doubled the SDA effect.
• 6.6. Deletion of alanine from the diet caused no significant effect on SDA, while deletion of phenylalanine caused a highly significant elevation in SDA.

     

Cellular and intracellular localization of catalase and acid phosphatase in the midgut of Lumbricus terrestris L.: A cell fractionation study

• 1.1. Cellular and intracellular localization of catalase and acid phosphomonoesterase in the midgut of Lumbricus terrestris was studied by use of tissue fractionation.
• 2.2. At least 60–70% of the catalase resides in the chloragocyte cytosol and the remaining 30–40% resides in gut epithelium peroxisomes.
• 3.3. One of the main functions of the chloragocyte catalase is probably scavenging for H₂O₂ arising from the interaction between blood heme-protein and oxygen.
• 4.4. A simple method for the histochemical detection of cytosol catalase is proposed.
• 5.5. About 10% of the gut acid phosphatase resides in chloragocyte lysosomes. The chloragosomes contain no acid phosphatase.

     

The effects of osmotic stressors on the stenohaline carp (Cyprinus carpio)

• 1.1. Carp were acclimatized to different concentration of urea and mannitol.
• 2.2. The fish survived in 300 mOsm urea and 262 mOsm mannitol for a longer period. Higher concentrations were only tolerated for a short time.
• 3.3. Urea penetrated into the animals. The internal concentration of urea in plasma was nearly equal to the outside concentration after 7 days. Therefore a very high internal osmolality was adjusted (sum of normal and urea osmolality).
• 4.4. Urea treatment only resulted in changes of Ca level, while the concentration of other electrolytes was not clearly varied.
• 5.5. Extracellular space of muscle was reduced while the intracellular space remained unchanged after urea treatment.
• 6.6. Mannitol treatment resulted in changes of electrolyte concentrations due to dehydration.
• 7.7. After 1 day of treatment the concentration of Na in plasma decreased which might indicate the limitation of tolerance.
• 8.8. Immediate shrinkage of ICS and, later, reduction of ECS were clear reactions to mannitol influence.

     

Effects of lysine administration on plasma arginine and on some nitrogenous catabolites in rainbow trout

• 1.1. Rainbow trout were fed either graded levels of lysine (0.8, 1.8 and 3%) at a constant level of arginine (1.4%) or excess arginine (2.4%) at a fixed level of lysine (1.8%).
• 2.2. Increasing the dietary lysine level affected plasma urea, plasma arginine and ammonia excretion.
• 3.3. Trout fed graded levels of lysine received an arginine challenge (U¹⁴C-l-arginine) and it was found that excess dietary lysine led to a decrease in arginine degradation.
• 4.4. Injection of l-lysine induced a decrease in urea excretion, while injection of l-arginine increased both urea and ammonia excretion in control well-fed trout.
• 5.5. These results are discussed in the light of current knowledge on the antagonism between lysine and arginine.

     

Influence of temperature,rate of feeding and body weight on nitrogen metabolism of bream,Abramis brama L

• 1.1. Measurements of the rate of nitrogen consumption, total nitrogen and ammonia excretion and nitrogen absorption of bream, Abramis brama L. (body weight range 0.4–519 g wet wt) were made at 10, 15 and 20 C.
• 2.2. Fish were fed once daily on live zooplankton collected in Lake Balaton and cultured Tubifex sp. at 5–15% of their body weight.
• 3.3. Fish size and temperature had a combined effect on the rate of total nitrogen excretion. Total nitrogen excretion did not increase proportionally with an increase in consumption.
• 4.4. On average, 52–80% of the nitrogen consumed with food was excreted by bream.
• 5.5. The greatest part of total nitrogen excretion was ammonia and its proportion in the total ranged between 53 and 75%.
• 6.6. Temperature did not have any significant effect on the proportion of excreted ammonia and the rate of excreted total nitrogen was the only factor determining its proportion in the total.
• 7.7. The rate of nitrogen absorption of bream was surprisingly very high.

     

[14C]PEG-4000, chloride,chloride/potassium and sodium spaces as indicators of extracellular phase volume in the tissues of rainbow trout,Salmo gairdneri richardson

• 1.1. Estimates of extracellular phase volume and cellular electrolyte concentrations based on [¹⁴C] PEG-4000, chloride, chloride/potassium and sodium spaces were compared at three epaxial muscle sites and in cardiac muscle, liver, gut, spleen and brain samples of rainbow trout.
• 2.2. [¹⁴C] PEG-4000 appeared to provide realistic estimates of tissue water distribution and cellular ion levels in brain and is suitable for use with epaxial and cardiac muscle, gut and spleen but not liver.
• 3.3. [¹⁴C] PEG-4000, chloride and chloride/potassium spaces were comparable in epaxial muscle, cardiac muscle and gut. Thus, no advantage is associated with use of the former rather than ion-defined estimates of extracellular phase volume in these tissues.
• 4.4. [¹⁴C]PEG-4000 and sodium spaces appear to be preferable to chloride and chloride/potassium spaces as indicators of tissue water distribution in spleen.
• 5.5. Sodium provides unrealistic estimates of extracellular phase volume in tissues other than spleen and liver.

     

Protein digestion and ion concentrations in rainbow trout (Salmo gairdnerii Rich.) digestive tract in sea- and fresh water

• 1.1. Rainbow trout maintained in fresh water or Actapted to sea-water for 24 hr were fed casein-based dry diet. After feeding, fish were kept in fresh water (FW) or transferred to artificial sea-water (SW) and sacrificed after 10 or 20 hr.
• 2.2. The digestive tract was separated into five parts: stomach, pyloric caeca region, middle intestine and two equal lengths of rectum.
• 3.3. The content of these parts was analysed for ions Na⁺, K⁺, Cl⁻, Mg²⁺ and for free, peptide and total amino acids.
• 4.4. In the fish stomach all ions, with the exception of Ca²⁺, indicate drinking of sea-water. In the pyloric caeca region Na⁺ appears to be efficiently absorbed in SW fish but influxed in FW fish. In the rectum of SW fish K⁺ appears to be reabsorbed but Na⁺ concentrated in faeces.
• 5.5. Free amino acid concentrations were always higher in gut lumen of SW than in FW fish in respect to time after feeding and portion of intestinal content. Free amino acids constitute at most 7.4–8.7% of total amino acids in the content of pyloric caeca region.
• 6.6. Peptide amino acids, being mostly di-, tri- and tetra-peptides, increased in stomach content from 14.7 to 28.4% of the total, from 6 to 10 hr after a meal in SW fish. Peptide amino acids constituted 80.3–89.0% of total amino acids in intestinal content of the pyloric caeca region. These peptide portions decreased in the mid-intestine (47.5–52.5%) and increased again in the rectum (73.6–76.0%).
• 7.7. It was concluded that in rainbow trout fed in both sea- or fresh water, ion concentrations do not seem to interfere with protein digestion and nutrient absorption in alimentary tract.

     

The effect of water loss upon the urate,urea and ammonia content of the egg of the Japanese quail Coturnix coturnix japonica

• 1.1. The urate, urea and ammonia content of the whole egg of the Japanese quail was measured in late incubation in eggs subject to different rates of water loss.
• 2.2. High rates of water loss substantially increased egg urate content, but had little or no effect on urea or ammonia content.
• 3.3. Allopurinol, an inhibitor of urate synthesis, reduced egg urate content to low levels, but produced no effect on urea content, and a small reduction in ammonia content.
• 4.4. The urea concentration of the embryo was lower than in allantoic fluid.
• 5.5. It is concluded that urate production by the avian embryo is primarily concerned with the modification of allantoic fluid composition.

     

Metabolism of ingested indole compounds in the gut of three species of heteroptera

• 1.1. All kinds of indole compounds used for the experiment were more or less metabolized in the gut of Dolycoris baccarum, Eurydema rugosum and Elasmostethus humeralis.
• 2.2. The metabolic pattern of the bugs was classified into four types (I–IV) for several indole compounds in the same way as for IAA.
• 3.3. The IAA metabolites in the excreta of the three species were probably the high-molecular compound combining with such substances as amino acids, sugars or proteins to some position of indole nucleus.
• 4.4. The crude excreta of E. humeralis fed with each of several indole compounds had a significant auxin activity.
• 5.5. Most of the metabolites of indole-3-acetaldehyde in the excreta of E. humeralis had also a significant auxin activity.
• 6.6. The significance of auxin metabolism in the gut of the bugs and the difference of auxin metabolism between aphids and bugs are discussed.

     

Studies on the nutrition of the supralittoral isopod Ligia pallasii using chemically defined artificial diets: Assessment of vitamin,carbohydrate, fatty acid,cholesterol and mineral requirements

• 1.1. An artificial diet, consisting of a dry aggregate of 59 chemical substances, was used to assess the requirements of the sea slater Ligia pallasii for vitamins, carbohydrates, fatty acids, cholesterol and minerals.
• 2.2. Good growth and survival of L. pallasii was obtained on the diet, comparable to that on seaweeds and to that shown by a field population.
• 3.3. No dietary requirements for vitamins, fatty acids or cholesterol were shown for periods of 40 weeks or more for L. pallasii.
• 4.4. Carbohydrates were shown to be required by L. pallasii in its diet, in the order: starch, lactose > maltose, glucose > sucrose, cellulose.
• 5.5. Dietary requirements for minerals were, in order: calcium, magnesium, phosphorus > copper, nickel, zinc > iron, manganese, sulphur > iodine, silicon.
• 6.6. The results are discussed in relation to the role of gut bacteria in supplying required nutrients to their isopod hosts and the enhancement of this process through coprophagic behaviour.

     

Interrelationship between metabolism of tritiated water, 22sodium and dry matter intake by beef cattle consuming wheat straw and poultry litter in free choice

• 1.1. Metabolism of tritiated water and ²²sodium was studied in six beef cows under Mediterranean summer conditions in order to find whether the turnover of these tracers can be used to evaluate pasture intake.
• 2.2. The diet of the cows included ad libitum access to two components which were given separately in different troughs: one was poultry litter and the other was wheat straw, to simulate the dry pasture.
• 3.3. Voluntary daily dry matter intake (111 g/kg^0.75) was unexpectedly high considering the low digestibility of the feed.
• 4.4. The assumptions of constant ratios of water intake to water turnover and of dry matter intake to water intake were confirmed. Consequently, dry matter intake was determined accurately from water turnover measurements.
• 5.5. Sodium intake was practically equal to sodium turnover and most of the sodium secreted in feces was of endogenous origin.
• 6.6. Pasture intake can be predicted from sodium turnover once the concentration in feed and water consumed is known.

     

Evidence for hyporegulation in the calanoid copepod,Acartia tonsa

• 1.1. The euryaline calanoid copepod, Acartia tonsa, maintains haemolymph Na below that of the external medium in salinities above 34^o_oo (475 mM Na).
• 2.2. The measured transepithelial electrical potential. −9.97 ± 1.0 mV, indicates that Na is regulated out of electrochemical equilibrium.
• 3.3. Water osmotically lost in hyporegulation is replaced by Na-dependent absorption by the gut.
• 4.4. High osmotic water permeability is evidenced by the fact that with an increase in external salinity from 475 mM Na to 580 mM Na the copepod's drinking rate nearly doubles.
• 5.5. Sodium efflux measurements indicate that ionic permeability is much lower than other hyporegulating crustaceans.
• 6.6. The energetic advantage of hyporegulation in this species is considered.

     

Cellulose digestion by the firebrat Thermobia domestica

• 1.1. A highly efficient cellulose digestion could be demonstrated in a primitive insect species, Thermobia domestica (Thysanura:Lepismatidae), by the application of a uniformly ¹⁴C-labelled substrate.
• 2.2. Gut extracts exhibit distinct hydrolytic activities toward different cellulosic substrates (cellobiose, sodium carboxymethylcellulose and microcrystalline cellulose). Therefore, the complete cellular complex must be present.
• 3.3. Besides cellulases, several other carbohydrates occur in the digestive juice, thus reflecting the omnivorous feeding habits of the insect.
• 4.4. The crop was found to be the main site of carbohydrate digestiopn, also including cellulolysis.
• 5.5. It is very likely that the cellulolytic enzymes derive from the gut tissues of the firebrat.

     

The peculiarities of nitrogen excretion in sturgeons (Acipenser ruthenus) (Pisces,Acipenseridae)—I. the influence of ration size

• 1.1. The nonfaecal nitrogenous excretion rate in starved sterlet fingerlings and fingerlings fed on different rations was investigated. The weight of the fish and temperature of the water was 43 g and 17.5°C, respectively.
• 2.2. In the nonfaecal excrements of starved sterlets the ammonia: urea ratio was substantially lower than in teleosts. This ratio was found to be 1.4:1.
• 3.3. In fed sterlets the urea excretion rate was higher than in starved ones but independent of ration size.
• 4.4. During the day the urea excretion rate in sterlets was constant.
• 5.5. The ammonia excretion rate accelerated 2 hr after feeding and reached its peak duration 6–11 hr after depending on the ration size.
• 6.6. Total ammonia output in the sterlet increased following the increase of ration size up to 8.4% of body wt. Further increases in ration size did not cause the corresponding elevation of ammonia excretion rate.