On the role of phylogeny in determining activity patterns of rodents

Evolutionary plasticity is limited, to a certain extent, by phylogenetic constraints. We asked whether the diel activity patterns of animals reflect their phylogenies by analyzing daily activity patterns in the order Rodentia. We carried out a literature survey of activity patterns of 700 species, placing each in an activity time category: diurnal, nocturnal, or active at both periods (a-rhythmic). The proportion of rodents active at these categories in the entire order, was compared to the activity patterns of species of different families for which we had data for over ten species each: Dipodidae, Echimyidae, Geomyidae, Heteromyidae, Muridae, and Sciuridae. Activity times of rodents from different habitat types were also compared to the ordinal activity time pattern. We also calculated the probability that two random species (from a particular subgroup: family, habitat, etc.) will be active in the same period of the day and compared it to this probability with species drawn from the entire order. Activity patterns at the family level were significantly different from the ordinal pattern, emphasizing the strong relationship between intra-family taxonomic affiliation and daily activity patterns. Large families (Muridae and Sciuridae) analyzed by subfamilies and tribes showed a similar but stronger pattern than that of the family level. Thus it is clear that phylogeny constrains the evolution of activity patterns in rodents, and may limit their ability to use the time niche axis for ecological separation. Rodents living in cold habitats differed significantly from the ordinal pattern, showing more diurnal and a-rhythmic activity patterns, possibly due to physiological constraints. Ground-dwelling rodents differed significantly, showing a high tendency towards a-rhythmic activity, perhaps reflecting their specialized habitat. Electronic supplementary material Electronic supplementary material is available for this article at and accessible for authorised users.     

Green cocoons in silkworm Bombyx mori resulting from the quercetin 5-O-glucosyltransferase of UGT86, is an evolved response to dietary toxins

The glycosylation of UDP-glucosyltransferases (UGTs) is of great importance in the control and elimination of both endogenous and exogenous toxins. Bm-UGT10286 (UGT86) is the sole provider of UGT activity against the 5-O position of quercetin and directly influences the formation of green pigment in the Bombyx cocoon. To evaluate whether cocoon coloration evolved for mimetic purposes, we concentrated on the expression pattern of Ugt86 and the activities of the enzyme substrates. The expression of Ugt86 was not only detected in the cocoon absorbing and accumulating tissues such as the digestive tube and silk glands, but also in quantity in the detoxification tissues of the malpighian tubes and fat body, as well as in the gonads. As in the green cocoon strains, Ugt86 was clearly expressed in the yellow and white cocoon strains. In vitro, the fusion protein of UGT86 showed quercetin metabolic activity. Nevertheless, Ugt86 expression of 5th instar larvae was not up-regulated in the silk gland by exogenous quercetin. However, it was significantly up-regulated in the digestive tube and gonads (P < 0.05). A similar result was observed in experiments where larvae were exposed to rutin, an insect resistance inducer and growth inhibitor typically found in plants, and to 20-hydroxylecdysone (20E), an insect endocrine and plant source hormone. On the contrary, up-regulated Ugt86 expression was almost nil in larvae exposed to juvenile hormone III (P > 0.05). The results of HPLC revealed that a new substance was formed by mixing 20E with the recombinant UGT86 protein in vitro, indicating that the effect of Ugt86 on 20E was similar to that on exogenous quercetin derived from plant food, and that the effect probably initiated the detoxification reaction against rutin. The conclusion is that the reaction of Ugt86 on the silkworm cocoon pigment quercetin is not the result of active mimetic ecogenesis, but derives from the detoxification of UGTs.     

Fluorocarbons as blood substitutes. Toxicity in the rat]

Liquid fluorocarbons, having high solubility for gases (O2, CO2...) have been used as artificial blood substitutes in animals with variable results. The great diversity of these products and the lack of reproductiveness in their composition have not permitted, up to now, a standardization of their utilisation norms. Our work was to study the toxicity, in the rat, of a new kind of fluorocarbon emulsion (E-66, Ugine-Kuhlmann, France) used as an artificial blood substitute during exchange-perfusion. The short survival of the rats is in opposition to the good in vitro results obtained in other experiments (high solubilities of oxygen and dioxide carbon). The toxicity of this fluorinated emulsion is demonstrated by histologic lesions in lungs, liver and kidneys and the great amount of fluor stored in these organs. The mechanism of this toxicity is still to be demonstrated. Hepatic lesions (hyperhemia with dilatation of central veins and sinusoids) and pulmonary lesions (vascular congestion, alveolar oedema) prove a circulatory disturbance leading to right-sided cardiac failure. However, cellular degenerescence lesions, observed in hepatocytes and renal tubular cells, do not permit to exclude formally a cellular toxicity of the E-66 emulsion.     

Computational Phenotyping of Two-Person Interactions Reveals Differential Neural Response to Depth-of-Thought

Reciprocating exchange with other humans requires individuals to infer the intentions of their partners. Despite the importance of this ability in healthy cognition and its impact in disease, the dimensions employed and computations involved in such inferences are not clear. We used a computational theory-of-mind model to classify styles of interaction in 195 pairs of subjects playing a multi-round economic exchange game. This classification produces an estimate of a subject''s depth-of-thought in the game (low, medium, high), a parameter that governs the richness of the models they build of their partner. Subjects in each category showed distinct neural correlates of learning signals associated with different depths-of-thought. The model also detected differences in depth-of-thought between two groups of healthy subjects: one playing patients with psychiatric disease and the other playing healthy controls. The neural response categories identified by this computational characterization of theory-of-mind may yield objective biomarkers useful in the identification and characterization of pathologies that perturb the capacity to model and interact with other humans.     

Study of the mutagenic activity of 6 hepatotoxic pharmaceutical drugs in the Salmonella typhimurium microsome test, and the HGPRT and Na+/K+ ATPase system in cultured mammalian cells

Several pharmaceutical drugs show strong hepatotoxicity during therapeutic use. We have studied 6 of them: aminophenazone, clofibrate, nifuroxazide, oxamniquine, perhexiline maleate, tienilic acid. Their mutagenicity was assessed in the Ames test on 6 strains of Salmonella typhimurium, and in V79 Chinese hamster lung cells using a rat-hepatocyte-mediated metabolic activation system and the HGPRT and Na+/K+ ATPase assay. Nifuroxazide was positive in the Ames test in two Salmonella strains (TA100, and TA100 Fr1). In the hepatocyte-mediated mammalian V79 cell system, nifuroxazide, clofibrate and aminophenazone were negative; oxamniquine and tienilic acid were positive with and without metabolic activation in tests looking for ouabain and 6-thioguanine resistance. Perhexiline maleate was negative for the direct induction of 6-thioguanine resistance without metabolic activation, and positive after metabolisation mediated by primary rat's hepatocytes. These results suggest the need for some caution in the use of some pharmaceutical drugs because of hepatotoxicity and because 3 out of 6 drugs were shown to be slightly mutagenic in mammalian cells.     

Studies on the mucilaginous layer of barley (Hordeum vulgare) roots

The nature and composition of the external, mucilageneous layer of barley roots was studied by extraction methods and electron microscopy. Barley roots were extracted with chloramphenicol-supplemented water at 35°C, with NH₄Cl at various concentrations and with pectinase solutions. The kinetics of transfer of bacteria, total and reducing sugars, proteins, Ca⁺⁺ and K⁺ was studied, and the removal of the mucigel from the extracted roots was followed under the electron microscope. Within 2 to 3 hours of treatment with water, the rate of release of sugars, ions, proteinaceous material and bacteria, was reduced to almost zero. Increasing concentrations of ammonium chloride enhanced transfer of ions to the extracting solution but affected sugar extraction to a lesser extent. Electron micrographs of ammonium chloride-extracted roots revealed that the amorphous, rather than the fibrillar fraction of the mucigel was removed. At 10³ meq of NH₄Cl, distortion of the epidermal layer of the extracted roots was observed. With pectinase as an extractant, there was some enhancement of sugars and ions transfer from the roots to the extracting solution. Electron micrographs showed that the main site of extraction of pectinase was the boundary layer between the root surface and the mucigel. Paper chromatography of the acid hydrolyzate of the water extracted, ethanol-precipitated fraction showed the presence of compounds identical in Rf values to D-glucose, D-arabinose, D-glucuronic acid and D-galacturonic acid. Present methods available for the extraction of the mucigel do not allow the differentiation between extracted pectic compounds which originate from the internal root tissue, and the mucigel. re]19751128 Dept. of Field Crops Dept. of Soil and Water Sciences Dept. of Microbiology and Phytopathology     

Mutagenic activity of 4 active-principle forms of pharmaceutical drugs. Comparative study in the Salmonella typhimurium microsome test, and the HGPRT and Na+/K+ ATPase systems in cultured mammalian cells

The nitroimidazole derivatives used in human therapy have shown a strong mutagenic activity in bacterial tests using Ames strains of Salmonella typhimurium. Our study compared the response of 4 products of this family on bacterial target cells as well as on mammalian target cells (Chinese hamster V79 cells). The strong positive response on TA100 was greatly reduced on the nitroreductase-deficient strain TA100 Frl. Furthermore, no mutagenic activity was found in V79 mammalian cells that we examined for ouabain and 6-thioguanine resistance.