CCK-58 is the only detectable endocrine form of cholecystokinin in rat

CCK-58 differs from CCK-8 in patterns of expression of pancreatic secretion of fluid and amylase and gallbladder contraction. These differences have physiological relevance only if CCK-58 release is stimulated by nutrients entering the intestine and if CCK-58 circulates in sizeable amounts. In this study, we report that when radiolabeled CCK-58 is added to rat blood and plasma is formed, there is extensive loss and degradation of the radioactive peptide. Therefore, a new method was developed to minimize loss and degradation of this label. This method recovered >85% of the label with no detectable degradation. Furthermore, the optimized method recovered all unlabeled exogenous cholecystokinin molecular forms in >80% yields. Blood from fasted rats and rats in which cholecystokinin release was stimulated by the trypsin inhibitor camostat contained only CCK-58 (3.5 +/- 0.5 and 17 +/- 1.5 fmol/ml, respectively). Because CCK-58 predominates in the blood, this molecular form should be used in studies on the physiology and pathophysiology of cholecystokinin.     

Metabolism of L-beta-lysine by a Pseudomonas. Purification and properties of a deacetylase-thiolesterase utilizing 4-acetamidobutyryl CoA and related compounds

A deacetylase-thiolesterase that cleaves both the amide and thiolester bonds of 4-acetamidobutyryl CoA has been highly purified from extracts of Pseudomonas B4 grown in a medium containing L-beta-lysine (3,6-diaminohexanoate) as the main energy source. The enzyme has a molecular weight of about 275,000 and contains 8 apparently identical subunits of 36,500 daltons. Products of 4-acetamidobutyryl CoA degradation are stoichiometric amounts of CoASH and acetate, variable amounts of 4-aminobutyrate and its lactam, 2-pyrrolidinone, and a little 4-acetamidobutyrate. The relative yields of 4-aminobutyrate and 2-pyrrolidinone are determined by the enzyme level. At high enzyme levels the 4-aminobutyrate/pyrrolidinone ratio is about 2, whereas at low enzyme levels only pyrrolidinone is formed. Under the latter conditions, 4-aminobutyryl CoA accumulates transiently and is converted nonenzymatically to pyrrolidinone and CoASH. Since the enzyme does not form 4-aminobutyrate from synthetic or enzymatically formed 4-aminobutyryl CoA, we conclude that a 4-aminobutyryl CoA-enzyme complex is the actual precursor of 4-aminobutyrate, whereas free 4-aminobutyryl CoA is the precursor of pyrrolidinone. Several analogs of 4-acetamidobutyryl CoA containing different amino acid or amide moieties, and several simple acyl CoA compounds are utilized by the enzyme; 4-propionamidobutyryl CoA and 5-acetamidovaleryl CoA are most readily decomposed. Acetyl CoA is a very poor substrate. 3-Acetamidopropionyl CoA is first converted to acetate and beta-alanyl CoA and the latter compound is slowly hydrolyzed to beta-alanine and CoASH. Little deacetylase-thiolesterase is formed by bacteria grown in absence of beta-lysine, but another thiolesterase, lacking deacetylase activity, is produced. The deacetylase-thiolesterase catalyzes an essential step in the aerobic degradation of L-beta-lysine.     

The sleeper Bostrichthys sinensis (family Eleotridae) stores glutamine and reduces ammonia production during aerial exposure

Bostrichthys sinensis inhabits brackish water, living in the crevices of the river mouths of Shang Xi and Guangdong, China. In its natural habitat, it may encounter aerial exposure frequently during low tides, and it usually remains quiescent in the absence of water. Upon aerial exposure in the laboratory, the ammonia excretion rate decreased to one-fourth that of the submerged control. Although all the enzymes of the ornithine-urea cycle were detected in the liver of this fish, the activity of hepatic carbamoyl phosphate synthetase was too low for the cycle to be functioning. Indeed, ammonia accumulated in the tissues and was not converted to urea. Results indicate that ammonia produced through amino acid catabolism was detoxified to glutamine during the first 24 h of aerial exposure. The excess amount of glutamine stored in the muscle during this period couldaccount approximately for the reduction in ammonia equivalent excreted. There was indeed a significant increase in the activity of glutamine synthetase from the liver of specimens exposed to terrestrial conditions. In contrast to the production of alanine, formation of glutamine is energetically expensive. Since B. sinensis remained relatively inactive on land, the reduction in energy demand for muscular activity might provide it with the opportunity to exploit glutamine formation as a means to detoxify ammonia. After 72 h of aerial exposure, B. sinensis reduced internal ammonia production, possibly through reductions in proteolysis and amino acid catabolism, to avoid excessive accumulation of ammonia.     

Variables associated with peripartum traits in dairy cows. III. Effect of diets and disorders on certain blood traits

BLood samples were collected from 89 Holstein cows on days 220 and 250 of gestation, within 24 hr prepartum and postpartum and on day 30 postpartum. Balanced diets which contained either chopped hay (29 cows), hay crop silage (HCS; 30 cows) or corn silage (CS; 30 cows) were fed from day 220 of gestation to day 30 postpartum. The purpose was to determine if variations in certain blood traits were indicative of peripartum and postpartum disorders. The blood traits evaluated were concentrations of plasma total protein, whole blood hemoglobin, packed cell volume, and white blood cells, and serum glutamic oxalacetic transaminase (SGOT), glucose, urea nitrogen, calcium, inorganic phosphorus, magnesium, potassium and sodium. No blood trait was useful to predict a disorder prior to its visual signs with one possible exception. Serum glucose and calcium were lower and SGOT and magnesium were higher peripartum which was prior to death of three cows from fat cow syndrome.     

Characterization of the zebrafish vascular endothelial growth factor A gene: comparison with vegf-A genes in mammals and Fugu

Vascular endothelial growth factor (VEGF-A) is a key angiogenic growth factor which regulates vertebrate embryonic vascularization, adult physiology such as wound healing and reproduction as well as many human diseases. To understand the evolution and regulation of this gene in vertebrates, we have isolated and characterized the zebrafish vegf-A gene and compared it with VEGF-A genes of human, mouse as well as an in silico isolated VEGF-A homologue from pufferfish. Our results indicate that the zebrafish vegf-A gene is organized similarly to mammalian and Fugu VEGF-A genes, with eight exons interrupted by seven introns. However, zebrafish vegf-A introns are generally larger than mammalian introns while Fugu VEGF-A introns are much smaller. Furthermore, zebrafish exon 6 (z6) has a unique sequence while Fugu's exon 6 is highly homologous to the mammalian counterparts. Alternative splicing generates multiple vegf-A mRNA isoforms in zebrafish with Vegf(121) as the dominant isoform in adult and Vegf(165) as the dominant isoform in early embryos. The exon z6 containing isoform Vegf(12345z678) is only detected in heart, muscle, and early embryos while another isoform Vegf-A(1234577)(a)(8) is only detected in heart. Furthermore, no conserved 5' flanking sequences between zebrafish and Fugu were observed while numerous conserved regions exist between human and mouse in this area. These results suggest both conserved and diverged functions of VEGF-A from fish to mammals since the separation of these two groups from their common ancestor about 450 million years ago and a diverged regulation of this gene since the separation of zebrafish from Fugu. These data will be valuable for future studies of VEGF-A gene regulation and function in different vertebrates.     

Habitat requirements and local persistence of three damselfly species (odonata: coenagrionidae)

Habitat requirements and population persistence were investigated in three damselfly species, all coastal plain pond specialists: Enallagma recurvatum, E. laterale, and E. pictum. Because of geographic restriction, two are of special concern to conservation, E. recurvatum and E. laterale. We surveyed more than 70 ponds on Cape Cod, Massachusetts, and collected adult presence-absence data during the summers of 1999 and 2000. We achieved a detection rate approaching 100% for each species by visiting each pond up to three times. We looked for relationships between the presence of each damselfly species and presence of specific aquatic vegetation, the presence of the other Enallagma species, and the number of ponds within various distances of the 72 surveyed ponds. Using stepwise logistic regression, we found the following significant associations: E. recurvatum with the rush Juncus militaris; E. laterale with water lilies (Nuphar variegatum and Brasenia schreberi) the damselfly E. pictum, and the number of ponds within 2 km; and E. pictum with the water lily Nymphaea odorata, the damselfly E. laterale, and the number of ponds within 1.5 km and 2.5 km. Presence-absence data were used to calculate turnover and local extinction rates for each species between the two years. E. recurvatum's turnover and local extinction rates (33.3% and 41% respectively) were much higher than either E. laterale (9.8%, 11.5%) or E. pictum (7.7%, 10%). These results suggest that E. recurvatum occurs in a metapopulation, and that patch colonization rates might be important to local population persistence.