Urease activity of adherent bacteria in the sheep rumen

In experiments on six sheep fed on a low protein diet (6.2 g N/day), it was found that the urease activity of the rumen fluid did not change significantly in the first 6 hours after feeding and that it ranged from 45 to 75 nkat.ml-1. The major portion was bound to the bacterial fraction and formed about 70% of total rumen fluid activity. Urease activity determined in food particles with adherent bacteria removed from the rumen before and 3 and 6 hours after feeding ranged from 20 to 26 nkat.g-1 food (wet weight), and on rumen wall samples with adherent bacteria from 30 to 800 nkat per 2.5 cm2 tissue. Again, no significant changes correlated to the time after feeding were found. The results show that urease activity in the sheep rumen is localized on food particles and on rumen wall epithelium with adherent bacteria, as well as in the rumen fluid.     

Triglyceride synthesis by small-intestinal epithelium of the pig, sheep and chicken

1. A comparative study was made of triglyceride synthesis by the intestinal epithelium of pigs, sheep and chickens. In pig and chicken tissue both the glycerol 3-phosphate and the monoglyceride pathway of triglyceride synthesis were operative, but the former pathway predominated in sheep tissue. 2. The fatty acid specificity of the glycerol 3-phosphate pathway was studied in pig and sheep total-homogenate preparations. Maximum incorporation was obtained with myristic acid and palmitic acid under optimum conditions for each fatty acid. Lauric acid, myristic acid, oleic acid, linoleic acid and linolenic acid were inhibitory at concentrations above their optimum, but octanoic acid, decanoic acid, palmitic acid and stearic acid did not show this effect. 3. Subcellular fractionation located the glycerol 3-phosphate and monoglyceride pathways of triglyceride synthesis in the microsomes in all instances. Phosphatidate phosphohydrolase was associated with both the microsomes and the particle-free supernatant. 4. Glycerol 1-mono-oleate was incorporated into triglycerides to a greater extent than glycerol 1-mono-palmitate or glycerol 1-monostearate by microsomal preparations from pig and chicken. 5. A lipase specific for monoglycerides was detected in the particle-free supernatant of all the species examined.     

Absence of endo-beta-N-acetylglucosaminidase activity in the kidneys of sheep, cattle and pig.

The kidneys of man, sheep, cattle and pig were all found to contain 1-aspartamido-beta-acetylglucosamine amidohydrolase activity. However, among these, only human kidney was found to contain endo-beta-N-acetylglucosaminidase activity. The absence of this enzyme in the kidneys of sheep and cattle explains why the oligosaccharides accumulated in, and excreted by, sheep and cattle afflicted with disorders of glycoprotein catabolism (i.e. alpha-mannosidosis and beta-mannosidosis) contain two N-acetylglucosamine residues at the reducing terminus instead of one, as is the case for human patients afflicted with similar disorders.     

Cyclic nucleotide activity in gastrointestinal tissues and fluids.

Published values of adenosine 3′,5′-monophosphate (cAMP) and guanosine 3′,5′-monophosphate (cGMP) in gastrointestinal tissues and fluids have varied depending upon extraction and purification methods and assay procedures. Cyclic nucleotide levels in a variety of gastrointestinal tissues and fluids from several animal species were measured by the Gilman protein kinase assay for cAMP, and by a radioimmunoassay for cAMP and cGMP. The neutral alumina/Dowex-1-formate column was the most accurate for the preparation of bile and gastric juice samples for the measurement of cAMP and cGMP, as verifled by the use of column blanks, spiked samples, phosphodiesterase treatment, and serial sample dilution. Tissue samples gave consistent results regardless of the various column procedures employed.     

Telomeres and telomerase activity in pig tissues

The current state of the art concerning telomeres and telomerase stems almost exclusively from the analysis of protozoa, yeast, and a small number of mammals. In the present study, we confirm that the pig telomeric sequence is indeed T(2)AG(3), as previously suggested. By making use of sequence analysis of pig telomeric DNA variant telomeric repeats in the medial region of the telomeres, interspersed with canonical T(2)AG(3) repeats, were identified. This telomere organization is similar to the one present in humans. Analysis of terminal restriction fragments showed that the majority of telomeres from different pig tissues are longer than in humans but shorter than in Mus musculus. Telomeres from spermatozoa were found to be longer, ranging in size between 13 and 44 kb. Most of the somatic pig tissues expressed significant levels of telomerase activity, a situation more similar to mouse and that contrasts with the one in humans and dog. Moreover, the analysis of sperm cells from different epididymal compartments of an adult animal showed that telomerase activity is absent in maturing spermatozoa, suggesting that sperm telomere elongation is restricted during spermatogenesis.     

Alcohol dehydrogenase activity and isoenzyme distribution in the organs of cow, pig and sheep

The highest specific activities and the most complex isoenzyme patterns were found in livers of these species, characteristic isoenzymes were observed also in the core of adrenal glands. In spite of a general resemblance the isoenzyme patterns of liver alcohol dehydrogenase are specific for the species tested; the activities in most organs (and blood sera) increase in the sequence cow, pig and sheep. The activities in foetal bovine organs are substantially lower than those in organs of adult cows, the most pronounced increase in activities during the intrauteral development was observed in liver.     

Distribution of glutamate dehydrogenase and glutamine synthetase activity in the sheep and chicken digestive tract.

Glutamate dehydrogenase (GLDH, EC 1.4.1.3) and glutamine synthetase (GS, EC 6.3.1.2) activity were determined in the contents and tissues of the various parts of the sheep and chicken digestive tract, GLDH activity in the tissues of the sheep omasum, duodenum, rumen, reticulum, colon, caecum, jejunum and ileum ranged from 3.25+/-0.7 U (mumol/g dry weight . min) to 5.94+/-2.28 U; in the abomasum it was 9.67+/-1.27 U. GLDH activity in the contents of the ileum, abomasum, jejunum and duodenum varied from 0.85+/-0.19 U to 3.29+/-0.53 U and in the colon, caecum, reticulum, omasum and rumen from 6.34+/-2.64 U to 16.96+/-3.83 U. GS activity in the tissues of these parts of the digestive tract varied from 2.8+/-0.59 U to 8.6+/-1.4 U and their contents from 2.49+/-0.85 U to 10.76+/-2 U. GS activity in the contents of the colon was very low (0.26+/-0.07 U). In the tissues of the chicken duodenum, caecum, jejunum and ileum we found GLDH activity of 4.68+/-1.64 U to 7.96+/-1.73 U; in their contents it was 3.31+/-1.06 U to 3.8+/-0.73, but in the caecum it attained up to 66.7+/-24.3 U. GS activity was high from 57.6+/-2.0 U to 231+/-84 U in the tissues and 357+/-53 U to 383+/-76 U in the contents (in the caecum up to 2,500+/-233 U). The results show that conditions for the utilization of ammonia are present in the tissues and the contents in the whole of the sheep and chicken digestive apparatus. The hypothesis is confirmed that the different ability of ruminants and fowls to utilize ammonia formed from urea added to their feed, including ammonia formed by hydrolysis of blood urea, is due to the different GLDH and GS activity in their digestive tract as well as in their liver.     

Urease activity in microbiologically-induced calcite precipitation.

The role of microbial urease in calcite precipitation was studied utilizing a recombinant Escherichia coli HB101 containing a plasmid, pBU11, that encodes Bacillus pasteurii urease. The calcite precipitation by E. coli HB101 (pBU11) was significant although its precipitation level was not as high as that by B. pasteurii. Addition of low concentrations (5-100 microM) of nickel, the cofactor of urease, to the medium further enhanced calcite precipitation by E. coli (pBU11). Calcite precipitation induced by both B. pasteurii and E. coli (pBU11) was inhibited in the presence of a urease inhibitor, acetohydroxamic acid (AHA). These observations on the recombinant urease have confirmed that urease activity is essential for microbiologically-induced calcite precipitation. Partially purified B. pasteurii urease was immobilized in polyurethane (PU) foam to compare the efficacy of calcite precipitation between the free and immobilized enzymes. The immobilized urease showed higher K(m) and lower V(max) values, which were reflected by a slower overall calcite precipitation. However, scanning electron micrographs (SEM) identified that the calcite precipitation occurred throughout the matrices of polyurethane. Furthermore, PU-immobilized urease retained higher enzymatic activities at high temperatures and in the presence of a high concentration of pronase, indicating that immobilization protects the enzyme activity from environmental changes.     

Characteristics of purine nucleotide metabolism and GMP-reductase activity in chicken tissues

The [3H]guanosine and [3H]guanine label is shown to be distributed unevenly in the purine components of chicken tissues. 60 min after isotope administration about 80% of radioactivity is localized in xanthine and uric acid in the liver and duodenum, that agrees with high activity of purine nucleoside phosphorylase (EC 2.4.2.1) and guanine deaminase (EC 3.5.4.3). At the same time over 50% of label is found in the spleen in adenine nucleotides of the pool, RNA as well as in hypoxanthine and only 20% in oxypurines. Such a distribution of the label is in direct correlation with the activity of GMP-reductase (EC 1.6.6.8) catalyzing the reduction deamination of GMP in IMP.     

3-Mercaptopyruvate sulfurtransferase activity in guinea pig and rat tissues

Activities of 3-mercaptopyruvate sulfurtransferase (EC 2.8.1.2) in guinea pig tissues were determined and compared with those in the corresponding rat tissues. The activities in guinea pig tissues were found to be very low. The activity in the liver was 145.9 mumol pyruvate formed per g of fresh tissue per 15 min. This was 1/50 of the activity in the rat liver. Activities in the kidney and brain were 1/100 of the corresponding rat tissues. Those in the erythrocyte and heart were negligibly low and far less than 1/1000 of these tissues in the rat. Similarities between the guinea pig and patients with beta-mercaptolactate-cysteine disulfiduria are discussed.     

Regulation by cations of adenylate cyclase activity in chicken tissues

The effects of magnesium and sodium ions on adenylate cyclase activity in plasma membranes from chicken heart and eggshell gland mucosa were studied. It was found that the increase in magnesium chloride concentration from 5 to 40 mM results in the stimulation (4.1-fold) of the adenylate cyclase activity. The increase in sodium chloride concentration up to 150 mM stimulated the enzyme activity 2-fold. The stimulation of adenylate cyclase by magnesium and sodium ions was less pronounced in the eggshell gland. GTP did not activate adenylate cyclase. The activating effect of magnesium and sodium ions was accompanied by the attenuation of the enzyme sensitivity to NaF, guanylyl imidodiphosphate and isoproterenol. Activation by guanylyl imidodiphosphate was completely abolished in the presence of 40 mM magnesium chloride. It is assumed that high concentrations of the salt promote subunit dissociation of the adenylate cyclase regulatory protein and its interaction with the catalytic subunit in the presence of endogenous nucleotides. The differences in the adenylate cyclase sensitivity to cations in chicken heart and eggshell gland mucosa correlate with the amount of pertussis toxin substrate.     

Carboxylesterases (EC 3.1.1). A comparison of some kinetic properties of horse, sheep, chicken, pig, and ox liver carboxylesterases.

A comparative study of the kinetic be,avior of horse, sheep, chicken, pig, and ox liver carboxylesterases is reported. The enzymes exhibit similar specificites towards a series of phenyl esters in which the acyl group is varied, and towards a series of butyrate esters in which the alcohol group is varied. Non-Michaelis-Menten kinetics are exhibited by the horse enzyme in the hydrolysis of methyl and ethyl butyrates, and by the pig enzyme with ethyl butyrate. Each enzyme exhibits inhibition by one or more substrates. A simple scheme which accounts for both activation and inhibition is discussed. pH-k(cat) profiles for the horse and chicken liver carboxylesterase-catalyzed hydrolyses of phenyl butyrate demonstrate dependencies on pK(a)S of 4.75 and 5.0, respectively.     

Comparison of pig, sheep and chicken SCD5 homologs: Evidence for an early gene duplication event

Stearoyl-CoA desaturase (SCD) catalyzes the desaturation of saturated fatty acyl-CoA substrates at the delta-9 position. Multiple SCD isoforms are well characterized in rodents, especially in mice, where four isoforms have been described. In humans and cows, two SCD isoforms have been described: SCD1, which is a homolog of murine SCD1, and SCD5, which appears to be a distinct SCD gene rather than an ortholog of any of the four murine isoforms. In this paper, we describe for the first time SCD5 homologs in sheep, pigs and chickens. The SCD5 nucleotide sequences have notably higher GC content than SCD1 sequences, and the predicted protein sequences lack N-terminal PEST sequences typically found in SCD1 proteins. Similar to humans and bovines, the mRNA expression of sheep and pig SCD5 is greatest in the brain, and the mRNA expression of chicken SCD5 is greatest in the pancreas and brain. In contrast, SCD1 expression was found to be highest in adipose tissue in pigs and sheep, and liver in the chicken. This is the first report of an SCD5 homolog in a non-mammalian species, and suggests that SCD5 may be the result of an early gene duplication event that occurred before the divergence of mammals.     

Adrenal medullary basophilia in ox,pig and sheep

Summary In ox, pig and sheep the adrenaline storing cells are intensely basophilic compared with the noradrenaline storing cells when aldehyde fixed tissue is stained with toluidine blue at pH 5.0 and above. This has been shown to be due to carboxyl groups from the glutamate rich chromaffin granule soluble protein. In isolated chromaffin granules adenosine nucleotides also bind the dye. Fixation of adrenal medulla in agents not containing aldehydes, or the use of cryostat sections results in equal basophilia in the adrenaline and noradrenaline storing cells. The probable mechanism of the differential basophilia of the two sorts of medullary cells following aldehyde fixation is discussed.     

Changes in lactate dehydrogenase activity in chicken tissues in hyperthyreosis in ontogenesis

The lactate dehydrogenase activity in reactions of lactate oxidation and synthesis was studied in subfractions of the chicken brain, heart and liver at the embryonal, early postembryonal and adult stages of development after thyroxine administration. It has been shown that during embryogenesis thyroxine predominantly enhanced the rate of lactate oxidation in the mitochondrial tissues. A marked increase in the lactate synthesis was found in cytoplasm of the adult chicken tissues. Specificity of enzyme activity alterations was detected in the chicken brain during ontogenesis after thyroxine administration.