Infanticide in a mammal-eating killer whale population.

Infanticide can be an extreme result of sexual conflict that drives selection in species in which it occurs. It is a rarely observed behaviour but some evidence for its occurrence in cetaceans exists in three species of dolphin. Here we describe observations of an adult male killer whale (Orcinus orca) and his post-reproductive mother killing a neonate belonging to an unrelated female from the same population in the North Pacific.

Alterations in amino acid status in cats with feline dysautonomia.

Feline dysautonomia (FD) is a multiple system neuropathy of unknown aetiology. An apparently identical disease occurs in horses (equine grass sickness, EGS), dogs, rabbits, hares, sheep, alpacas and llamas. Horses with acute EGS have a marked reduction in plasma concentrations of the sulphur amino acids (SAA) cyst(e)ine and methionine, which may reflect exposure to a neurotoxic xenobiotic.

Vocal behavior of resident killer whale matrilines with newborn calves: the role of family signatures.

Studies of the vocal behavior of resident killer whales or orcas, Orcinus orca, in British Columbia have shown that matrilines have unique call repertoires consisting of up to 17 different call types. These call types cannot be attributed exclusively to specific behaviors, and their function in social contexts is poorly understood. This study investigated the change in call patterns of three resident matrilines in a changed social environment, before and up to one year after the birth of a calf.

Drug binding sites on chicken albumin: a comparison to human albumin.

Mammalian albumins have two main structurally selective ligand binding sites. Site I binds drugs such as azapropazone, phenylbutazone and warfarin; whereas benzodiazepines, some dansyl amino acids, such as dansylsarcosine, and short chain fatty acids like octanoic acid interact with site II. However, it is not known if non-mammalian albumins have similar binding loci.

Expression of mRNAs coding for the transforming growth factor-beta receptors in brain regions of euthyroid and hypothyroid neonatal rats and in adult brain.

The TGF-beta family of peptides has been postulated to play a role in control of the cell cycle but also may act in the developing brain to influence neuronal differentiation and survival. Because reception of TGF-beta signals requires the simultaneous expression of all three known receptor subtypes, we examined two neonatal rat brain regions in which neurogenesis has been largely completed. mRNA coding for all three receptors was detectable in both the forebrain and brainstem but only the type II receptor in brainstem showed a difference from adult levels of expression.

Tissue-specific inactivation of p53 tumor suppression in the mouse.

The p53 gene is the most frequent target of structural and functional genetic mutations in human cancer. Thus, considerable effort has been devoted to mapping the functional domains of p53 with regard to their impact on tumorigenesis in vivo. Studies have shown that the carboxy-terminal domain of p53 is sufficient for transformation in vitro.

Binding of sulphamethazine to pig plasma proteins and albumin.

The interaction of sulphamethazine (SMZ) with pig plasma proteins and albumin was studied by ultrafiltration and equilibrium dialysis. Binding to pig plasma proteins was monophasic (affinity approximately 9.0 mol/L x 10(3)) and the main binding protein was albumin.

A cluster of cases of feline dysautonomia (Key-Gaskell syndrome) in a closed colony of cats.

Twenty-five cases of feline dysautonomia (Key-Gaskell syndrome) occurred in a closed cat colony over a period of three weeks. The clinical and pathological signs were sufficiently similar to those reported during the 1982-1986 outbreak to establish a positive diagnosis. The special epidemiological and environmental circumstances of the outbreak provide a new insight into the cause(s) of the syndrome.

Welfare of calves - 2. Increase in vertebral artery blood flow following exsanguination by neck sticking and evaluation of chest sticking as an alternative slaughter method.

The role of the vertebral arteries in delaying loss of sensibility following neck sticking in slaughter calves was investigated. Vertebral artery blood flow was measured using probes before, during and after electrical stunning and slaughter. Systemic blood pressure, electrocorticogram, visually evoked responses and the occurrence of carotid occlusions were also recorded.

Preliminary evidence for the enterohepatic circulation of progesterone in the pig.

In two gilts, following doses of either 47.7 or 64.6 mumol progesterone, a secondary increase in steroid concentration in portal and mesenteric blood plasma occurred 35-40 min after dosing or 10-15 min after an intravenous (i.

p53-dependent apoptosis suppresses tumor growth and progression in vivo.

To determine the contribution of p53 loss to tumor progression, we have induced abnormal proliferation in the brain choroid plexus epithelium of transgenic mice using a SV40 T antigen fragment that perturbs pRB family function but does not affect p53 function. Tumors induced by this mutant develop slowly compared with those induced by wild-type T antigen. Suppressed tumor growth is directly attributable to p53 function, since rapid tumor development occurs when the T antigen fragment is expressed in p53-null mice.

Regulation of apoptosis in transgenic mice by simian virus 40 T antigen-mediated inactivation of p53.

Several proteins encoded by DNA tumor viruses are thought to disrupt cellular growth control by interacting with key cellular proteins, such as p53 and pRB, that normally function to regulate cell growth. However, the biological consequences of intracellular complexing between the viral oncoproteins and cellular proteins have remained unclear. Such complexes could either facilitate functional inactivation of the cellular proteins, leading to a loss-of-function phenotype, or could activate new functions, leading to a gain-of-function phenotype.

Induction versus progression of brain tumor development: differential functions for the pRB- and p53-targeting domains of simian virus 40 T antigen.

The ability of simian virus 40-encoded large T antigen to disrupt the growth control of a variety of cell types is related to its ability to interfere with certain cellular proteins, such as p53 and the retinoblastoma susceptibility gene product (pRB). We have used wild-type and mutant forms of T antigen in transgenic mice to dissect the roles of pRB, p53, and other cellular proteins in tumorigenesis of different cell types. In this study, using a cell-specific promoter to target expression specifically to brain epithelium (the choroid plexus) and to B and T lymphoid cells, we characterize the tumorigenic capacity of a T-antigen fragment that comprises only the amino-terminal 121 residues.

Absorption of N4-D-glucopyranosylsulphamethazine by rat everted intestinal sacs.

Absorption of the N4-D-glucose conjugate of sulphamethazine (glucose-SMZ, 0.5 mM) by isolated everted sacs of the rat small intestine was studied at 37 degrees and pH 6.6.

Use of transgenic mice reveals cell-specific transformation by a simian virus 40 T-antigen amino-terminal mutant.

We have used the multifunctional transforming protein, simian virus 40 T antigen, as a probe to study the mechanisms of cell growth regulation in the intact organism. T antigen appears to perturb cell growth, at least in part, by stably interacting with specific cellular proteins that function to maintain normal cell growth properties. Experiments in cultured cells indicate that at least three distinct regions of simian virus 40 T antigen have roles in transformation.

Responses in the voluntary intake of hay or silage by lactating cows to intraruminal infusions of sodium acetate or sodium propionate, the tonicity of rumen fluid or rumen distension.

Rumen-fistulated lactating cows were individually fed on hay or silage and intakes were monitored during 3 h treatment periods and for 2 h after. Each experiment used five, six or seven animals and the treatments were applied in a Latin Square design. Sodium acetate infusions of 1.

The effect of copper and heliotrope on the composition of bile in sheep.

The effects of interrupting the enterohepatic circulation (EHC) of bile salts for seven hours and of feeding copper and heliotrope alone and combined for 13 weeks, on bile flow and excretion of copper, zinc, iron and alpha-mannosidase were studied in sheep. Interruption of EHC reduced bile flow rate and increased the concentration of copper, zinc, iron and bile acids while alpha-mannosidase's activity remained stable. Changes in concentration were related to changes in bile volume for copper and zinc only.

Complex formation between the lymphotropic papovavirus large tumor antigen and the tumor suppressor protein p53.

The simian B-lymphotropic papovavirus (LPV) encodes a large tumor antigen (T antigen) which is 45% identical to both the simian virus 40 (SV40) and the polyomavirus (PyV) large T antigens. In transgenic mice, the transforming properties of the LPV T antigen are similar to those of the SV40 T antigen. However, little is known about its biochemical activities.

A surgical technique for the long term collection of bile in the pig and measurement of the biliary excretion of copper and zinc.

A method is described for surgically modifying the gastrointestinal tract of the pig which enables the long term collection of bile and measurement of bile flow and allows the pig to be kept unrestrained in a large pen. Three surgically prepared gilts grew at an average of 0.79 kg d-1.

Enhancement of tetrathiomolybdate-induced copper excretion in bile of sheep by the alpha 2-agonistic action of xylazine.

The effect of intravenous doses of cortisol and xylazine on the quantity of copper excreted in response to 100 and 200 mg doses of tetrathiomolybdate (TTM) was studied in seven sheep. Cortisol alone produced a non-significant 1.4-fold increase and had no enhancing action on the response to TTM.