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.     

The biology and physiology of alga-invertebrate symbioses. III. In situ measurements of photosynthesis and calcification in some hermatypic corals

In situ measurements of the rates of photosynthesis and calcification in three species of hermatypic corals were made at Eilat, in the Gulf of Aqaba, Red Sea. Experiments were made at 5, 20 and 35 m depth under unusually poor conditions of submarine illumination for the region, and at the relatively low water temperature (21°C) for coral growth which prevails there all year. Estimates of photosynthetic rates by both the ¹⁴C and oxygen methods indicated that the ¹⁴C method does measure gross photosynthesis in these organisms even at, and below, light compensation points. Substantial rates of carbon fixation in Acropora and Millepora show that, even under bad conditions, these organisms could survive autotrophically to at least 10 m depth, as also could the massive coral Goniastrea although this had much lower photosynthetic rates under the same conditions, compensated for by a much lower respiratory rate than the other two corals.Calcification rates were variable but showed a considerable increase in light as compared with the dark in all three species, and the rates did not decrease with depth as much as might have been anticipated from the reduction in photosynthesis and ambient light energy. Photosynthetic and calcification rates were similar to those reported for similar organisms both in the Caribbean and on the Great Barrier Reef.     

f-Ratio and its relationship to ambient nitrate concentration in coastal waters

The relationship between thef-ratio [NO₃^– uptake/(NO₃^–+ NH₄⁺) uptake] and ambient nitrate concentration was evaluatedfor eight data sets from coastal waters. The f-ratio increasedasymptotically with increase in nitrate concentration in mostdata sets. However, the rate at which f-ratio increased at lownitrate concentration (slope = m) and the maximum attained f-ratio(f_max) varied among regions; the initial slope varied most withvalues ranging in excess of an order of magnitude. The datawere analyzed in relation to environmental factors and methodologicalconsiderations known to influence the f-ratio. Ambient ammoniumconcentration was important in accounting for regional differencesin the f versus NO₃^– relationship. A further analysisof the data, relating f-ratio to the ratio of NO₃^–/(NO₃^–+ NH₄⁺) concentrations yielded a much more regionally consistentand approximately linear relationship; slopes varied by lessthan a factor of two in the extreme cases. Inclusion of knownalternative (aside from NH₄⁺) sources of reduced-N (e.g. urea)and correction for methodological/computational errors (isotopedilution) systematically reduce f-ratio estimates. Other factors,e.g. reduced-N uptake by microheterotrophs, may systematicallyincrease the f-ratio.     

[14C]-Glucose Metabolism during Shoot Bud Development in Cultured Cotyledon Explants of Pinus radiata

Excised cotyledons of Pinus radiata D. Don cultured under shoot-forming(plus benzyladenine) and non shoot-forming (minus benzyladenine)conditions for 10 and 21 days were fed U-[¹⁴C]-glucose for 3h in the light followed by a 3 h chase period. The labellingof individual metabolites as well as ¹⁴C incorporation intoprotein was assessed. It was found that the general metabolicpatterns were qualitatively the same in shoot-forming and nonshoot-forming conditions, however, metabolism leading to respirationas well as to the synthesis of some amino acids and proteinsynthesis was enhanced in the shoot-forming cultures. (Received February 16, 1987; Accepted July 8, 1987)     

Putrescine metabolism in excised cotyledons of Pinus radiata cultured in vitro

The metabolism of ¹⁴C-putrescine and the changes in the endogenous concentrations of putrescine, spermidine and spermine were studied when cotyledons of Pinus radiata D. Don were cultured under shoot-forming (SF, + N⁶-benzyladenine) and non-shoot-forming (NSF, - N⁶-benzyladenine) conditions. Differences in the total uptake of ¹⁴C-putrescine during a 2 h pulse feeding were not significant between the SF and NSF cotyledons except on day 3. The maximum uptake of label was on day 3 in the SF cotyledons, which released the highest amount of ¹⁴CO₂ as well. ¹⁴C from the labeled putrescine was incorporated mainly into γ-aminobutyric acid, aspartate and glutamate. High performance liquid chromatography of the endogenous polyamines indicated that spermidine was the most predominant polyamine in the cultured cotyledons of radiata pine. Spermine increased by about 60% in the SF and 25% in the NSF cotyledons between days 0 and 3 of culture.