The aggressive behaviour of individual male polecats (Mustela putorius, M. furo and hybrids) towards familiar and unfamiliar opponents

Experiments are described which were designed to investigate the significance of individual differences in aggressiveness between polecats and the relation between the familiarity of the opponent and the pattern and outcome of fighting.
The behaviour of Mustela putorius, M. furo and hybrids between the two species was investigated in an indoor arena of 16 m².
Two kinds of fighting between male polecats were recorded, "companion fighting" between cage mates, in which biting was inhibited and neither of the opponents became intimidated and "uninhibited fighting" between unfamiliar individuals from which a winner and loser generally emerged and a rank order formed.
Individual differences in aggressiveness were assessed by means of a scoring system which statistical analysis showed, generally, to be consistent for any one individual. The rank of an animal, however, was found not to be invariably related to its aggression score.
A number of other factors influencing fighting were investigated, the earlier introduction of one individual into the arena increases its chances of winning a fight; when offered a choice, male polecats fight strangers in preference to cage mates; and the separation of a group of cage mates for as little as 48 hours induces them to behave towards one another like strangers with the result that a rank order is formed. Factors which had no apparent effect on fighting between males were the weight of the individual or the presence of females.
The attributes of familiar and unfamiliar opponents are discussed in the light of these findings.     

Proteoglycan metabolism associated with mouse metanephric development: morphologic and biochemical effects of beta-D-xyloside

Morphology and de novo incorporation of [35S]sulfate into proteoglycans were studied in fetal mouse kidneys at the onset of organogenesis. Branching morphogenesis and nephron development in organ culture and in vivo were associated with de novo synthesis of chondroitin-SO4 and heparan-SO4 proteoglycans. The role of proteoglycan metabolism in metanephrogenesis was then studied by analysis of the effects of p-nitrophenyl-beta-D-xylopyranoside (beta-D-xyloside) on renal development and proteoglycan metabolism. Incubation of fetal kidneys in beta-D-xyloside at concentrations of 1.0 and 0.5 mM, but not at 0.1 mM, caused inhibition of ureteric branching and markedly diminished synthesis of a large Mr 2.0 X 10(6) Da chondroitin-SO4 proteoglycan. Incorporation of [35S]sulfate was stimulated at all beta-D-xyloside concentrations, reflecting synthesis of xyloside initiated dermatan-35SO4 chains. In contrast to dramatic effects on chondroitin-SO4 synthesis and ureteric branching, beta-D-xyloside had no effect on heparan-SO4 synthesis or on development of the glomerulus and glomerular basement membrane. We thus characterize the proteoglycans synthesized early in the course of renal organogenesis and describe observations which suggest an association between metabolism of chondroitin-SO4 proteoglycan and development of the ureter.     

The acceleration of linear DNA during pulsed-field gel electrophoresis

The velocity and orientation of T4 and lambda DNA have been measured for the first 20 s during pulsed-field gel electrophoresis in order to clarify the DNA motions that occur. For a square pulse with field strength E = 10 V/cm, the velocity of lambda DNA increases gradually to 10.5 microns/s in 1.0 s, declines to 8.6 microns/s, and then rises to a plateau value of 9.3 microns/s after 4 s. T4 DNA behaves similarly, but more slowly. Parallel measurements of fluorescence-detected linear dichroism show that the DNA becomes substantially aligned with its chain axis parallel to the electrophoretic field E after the pulse is applied. The alignment also shows an overshoot, an undershoot, and a plateau comparable to those seen for velocity. When the field strength increases, both the velocity and the alignment reach their peaks more quickly. For all field strengths and both molecular weights, the velocity peak occurs when the molecular center of mass has moved 0.3 to 0.5 L, where L is the chain contour length. A qualitative model is provided.     

Variable evolutionary stability of Y chromosomal repeated sequences in the genus Mus

The study reported here is an examination of the organization and evolution of three Y chromosomal repeated sequences, designated pBC10-0.6, pBC15-1.1, and pBA33-1.8, in five closely related species of the genus Mus. The species distributions of major restriction fragment length polymorphisms produced with a panel of restriction enzymes is used to develop the phylogenetic relationships between the five species studied. However, the apparent degree of relatedness among these species varied a great deal with each of the three probes and was also highly dependent on the particular restriction enzyme used. The usefulness for phylogenetic studies of closely associated sequences varying in evolutionary stability is discussed.     

Regio- and stereoselective regulation of monooxygenase activities by isoenzyme-selective phosphorylation of cytochrome P450

The phosphorylation of the two major phenobarbital-inducible cytochrome P450 isoenzymes IIB1 and IIB2 was increased in hepatocytes by the action of the membrane permeating cAMP derivatives N6-dibutyryl-cAMP and 8-thiomethyl-cAMP. Under these conditions the dealkylation of 7-pentoxyresorufin, a selective substrate of cytochrome P450IIB1 and P450IIB2 was markedly reduced. 16 beta-Hydroxylation of testosterone which is catalyzed specifically only by cytochrome P450IIB1 and IIB2 was strongly reduced; for 16 alpha-hydroxylation which is also catalyzed by cytochrome P450IIB1 and IIB2 but additionally by 3 further cytochrome P450 isoenzymes, this reduction was less pronounced; for the oxidation of the 17 beta-hydroxyl group which besides cytochromes P450IIB1 and IIB2 is additionally catalyzed not only by other cytochromes P450 but also by 17 beta-hydroxysteroid dehydrogenase there was a clear tendency of reduction which, however, no longer reached statistical significance. Hydroxylation at other positions of testosterone which are catalyzed by other cytochrome P450 isoenzymes were not significantly changed. Hence isoenzyme-selective phosphorylation of cytochrome P450 leads to a corresponding isoenzyme-selective modulation of monooxygenase activity which holds promise to be especially important as a fast regulation of the control of genotoxic metabolites.