Oxygen consumption and the evolution of order: negentropy criteria applied to the evolution of ants

Optimization of energy use by evolving organisms, predicted by theoretical extensions of the neo-Darwinian theory, i. contrasted with that of irreversible thermodynamics, which predicts an increase in orderliness and thus an increase in energy consumption per unit of biomass. We compared this index with estimates of social complexity among ant genera and species. Our results show that simple optimization models cannot explain experimental data, and that social complexity correlates differently with negentropy at different levels of analysis. Comparing the genera among Formicidae, workers (not colonies) from genera with highly social species are less negentropic than those of socially primitive ones. At the sub-generic level, social complexity correlated positively with negentropy among species, for major workers inAcromyrmex and for minor workers inAtta. The results illustrate the complexity of thermodynamic criteria in the study of evolution but also hint at their usefulness. In this case, they show that two different evolutionary routes to the complex Attini ant societies may exist.     

Survival of tumor fragments as a function of temperature: correlation with electric impedance]

The ability of small pieces of Rat Walker's tumour carcinome 256 to develop a subcutaneous tumour on another Rat is dependent on the value and the duration of heat treatment.     

Oxygen consumption and biosynthetic function in perfused liver from rats at different stages of development

Changes in mitochondrial function were studied in perfused liver from rats aged 24 – 365 days. Oxygen consumption together with the rates of gluconeogenesis, urea synthesis and ketogenesis were determined. Basal mitochondrial respiration as well as the ability of the liver to synthesize glucose, urea and ketone bodies declined from 24- to 365-day-old rats. On the other hand, on transition from 24 to 60 days the liver oxidation rate of hexanoate, sorbitol and glycerol is enhanced, but not of ketone bodies or palmitate. Our results show that the transition from weaning to middle age is accompanied by defined changes in hepatic substrate oxidation. From the observed time course of the decrease in basal and substrate-stimulated oxygen consumption, it is concluded that in rat liver cells a decline in respiratory chain function, long-chain fatty acid and ketone body metabolism, gluconeogenesis and ureogenesis occurs at a relatively early life stage. Received 19 June 1998; received after revision 11 September 1998; accepted 11 September 1998     

Montane and piedmont chorus frogs (Pseudacris triseriata): Metabolic rate as a function of temperature

Zusammenfassung Die Stoffwechselraten von Fröschen (Pseudacris triseriata) aus Tiefland- und Bergpopulationen wurden bei 10 C und 20 C bestimmt. Die beiden Populationen unterschieden sich nicht signifikant in der Stoffwechselrate bei den 2 Testtemperaturen.     

Variations in the hydrothermic contraction of the rat skin as a function of the age of the animals]

The tension developed in Rat skin by hydrothermal shrinkage is modified with ageing of the animals: the temperature of maximum tension decreases from birth to 1 month, then very slowly increases with age. At higher temperatures than that of maximum tension a relaxation occurs very rapidly in young Rats and in not yet senescent adult skins. These modifications appeared to be related to those of the nature of the intermolecular collagen cross-links with ageing.     

Changes in the distribution of gamma-glutamyl transferase in the organs of the mouse as a function of development]

In the Mouse, gamma-glutamyl transferase distribution changes with development in the kidney and the liver; on the contrary, its activity remains almost equal and low in other organs. In the liver, a low activity is observed in the fetus and the new-born up to the 3rd day of life; then it is no more measurable. In the kidney, the low enzyme activity of the fetus is multiplied by 10 in the 10 first days of life and by 50 in the 6 first weeks.     

Visual stimulus localization as a function of brightness

Résumé Dans une tâche consistant à localiser un point sur une barre horizontale ou verticale, on mesure l'information transmise en fonction de l'éclairement et de l'information du stimulus. On trouve une relation linéaire directe entre l'information transmise et le logarithme de l'éclairement. Cette relation reste valable pour diverses quantités d'information émise.

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Partly supported by the Fonds National belge de la Recherche Scientifique.     

Consideration on the effects of pollution at community and population level

Summary The effects of pollution at population level are considered in relation to demographic characteristics and overall to the birthrate. The direct and indirect effects of pollution on community structure is discussed. The influence of pollution may vary according to the food-chain structure; (as a consequence, the hazard ceteris paribus will be greater in freshwater communities than in marine ones). Relations between diversity and stability are discussed. In addition, the advantages and difficulties in using diversity and biotic indices for monitoring polluted water are taken into account.     

Oxygen consumption and14CO2 production in tissue of rats with chronic and acute selenite poisoning

Riassunto Nessuna influenza sull'attività respiratoria di cellule di fegati e reni di topi è stata notata quando gli animali sono stati trattati con somministrazioni acute o croniche di Na₂SeO₃. La diminuzione della produzione di¹⁴CO₂, quando i tessuti degli animali trattati con Na₂SeO₃ sono stati incubati con¹⁴C glucosio, suggerisce la possibilità di un aumento dell'attività catabolica dei lipidi.     

Variation in delayed hypersensitivity to methylated bovine serum albumin as as function of the dose and time of administration of cyclophosphamide]

The injection of Cy before immunization provokes an intensification of delayed-type hypersensitivity (DTH) to methylated bovine serum albumin (M-BSA) and a diminution of about 90% of the cell number in various lymphoid tissues. The relationship between these observations, the time of administration, the dose of injected Cy and the intensity of DTH reactions, allows us to formulate hypotheses concerning the physiological modulation of DTH.     

Intra-vascular glucocorticoid metabolism as a modulator of vascular structure and function

The ability of glucocorticoids to directly alter arterial function, structure and the inflammatory response to vascular injury may contribute to their well-established link with the development of cardiovascular disease. Recent studies have emphasised the importance of tissue-specific regulation of glucocorticoid availability by the 11 β-hydroxysteroid dehydrogenase (11HSD) isozymes, which inter-convert active glucocorticoids and their inactive metabolites. The expression of both type 1 and type 2 11HSDs in the arterial wall suggests that prereceptor metabolism of glucocorticoids may have a direct impact on vascular physiology. Indeed there is evidence that 11HSDs influence glucocorticoid-mediated changes in vascular contractility, vascular structure, the inflammatory response to injury and the growth of new blood vessels. Hence, inhibition of 11HSD isozymes may provide a novel therapeutic target in vascular disease. Received 19 September 2005; received after revision 1 November 2005; accepted 25 November 2005     

Consideration on the effects of pollution at community and population level.

The effects of pollution at population level are considered in relation to demographic characteristics and overall to the birthrate. The direct and indirect effects of pollution on community structure is discussed. The influence of pollution may vary according to the food-chain structure; (as a consequence, the hazard 'ceteris paribus' will be greater in freshwater communities than in marine ones). Relations between 'diversity' and 'stability' are discussed. In addition, the advantages and difficulties in using 'diversity' and 'biotic' indices for monitoring polluted water are taken into account.