Effect of injections of testosterone propionate on dominance relationships in a group of cows

In a group of eight heifers, four animals whose social ranks were 2, 4, 6, and 8 were injected with testosterone propionate for 70 days. They all became dominant over controls and did not modify their own relationships among themselves. This experiment was replicated 3 months after the end of the first treatment with the same group; animals whose ranks were 2, 4, 6, and 8 at the beginning of the second experiment were treated. Again they all became dominant over controls and did not modify their relationships among themselves. Eighty percent of relationships modified by the first or the second treatment remain unchanged without any hormonal support for 4 to 10 months. A first analysis of social interactions does not seem to indicate a higher increase in the frequency of aggressive interactions in treated animals.     

Effect of fermented milk intake on plasmid transfer and on the persistence of transconjugants in the digestive tract of gnotobiotic mice

Plasmid transfer occurs in the digestive tract and the transconjugants may become durably established. The aim of the present work is to investigate the effect of probiotics on plasmid transfer and on establishment of transconjugants in the gut. Plasmid transfers were carried out in the digestive tract of germ free mice associated with an E. coli K12 donor strain harboring three plasmids (R388, self-transmissible, pCE325 and pUB2380, mobilisable,) and an E. coli recipient strain, PG1, of human origin (Duval-Iflah et al., 1994). Milks fermented with either Lactobacillus bulgaricus or Streptococcus thermophilus or symbiosis, S85, of both strains were given daily as 1/3 of food diet. Fermented milks have no effect on the transfer of R388 and pUB2380 except a slight increase of TC(R388) with milk fermented with S85. Long term ingestion of milk fermented with S85 inhibited the formation and the establishment of transconjugants TC(pCE325). Milk fermented with L. bulgaricus lowered the population density of TC(pCE325) in animals where they were already established. This phenomenon was reversible, since the density of TC(pCE325) increased in the same animals after cessation of supplementation. Bacterial cultures obtained in MRS broth and given in state of drinking water were compared with fermented milks. Bacterial cultures with L. bulgaricus and with S85 favoured the establishment of TC(pCE325). These results indicate for the first time that probiotics have various effects on the formation and/or establishment of transconjugants in the gut of axenic mice. The effects depend on whether the probiotics were cultivated in milk or in MRS, indicating that bacterial metabolites and viable bacteria can be involved.     

Virus-like particles in cells of the sponge Verongia cavernicola (demospongiae,dictyoceratida) and accompanying tissues changes

Isometric particles have been observed in the nuclei of giant cells occurring in a disturbed area of the tissue of the sponge Verongia cavernicola. Morphological similarities are apparent between these particles and adenoviruses. In the same area, other giant cells, probably related to the preceding, contain either nuclear rings or cytoplasmic granules of possible viral nature.     

Finding flexible patterns in a text: an application to three-dimensional molecular matching

Finding certain regularities in a text is an important problemin many areas, e.g. in the analysis of biological moleculessuch as nucleic acids or proteins. In the latter case, the textmay be sequences of amino acids or a linear coding of three-dimensionalstructures, and the regularities then correspond to lexicalor structural motifs common to two, or more, proteins. We firstrecall an earlier algorithm that found these regularities ina flexible way. Then we introduce a generalized version of thisalgorithm designed for the particular case of protein three-dimensionalstructures, since these structures present a few peculiaritiesthat make them computationally harder to process. Finally, wegive some applications of our new algorithm on concrete examples     

The effect of 1.25 dihydroxyvitamin D3 on binding and internalization of epidermal growth factor in cultured cells : Studies on BT-20 cells using quantitative electron microscope autoradiography

The biological effects of 1.25(OH)₂D₃ on epidermal growth factor receptor (EGF-R) and on EGF internalization were examined in human mammary carcinoma BT-20 cells. In this cell line, with known amplification of the epidermal growth factor receptor gene, EGF was not stimulatory for growth. Biological assay and quantitative EM autoradiography combined with iodinated ligand binding to specific receptors demonstrated that the number of binding sites per unit of length of plasma membrane was 2.48-fold higher in treated than in control cells. ¹²⁵I-EGF was progressively internalized in a time- and temperature-dependent manner after selective association with the membrane-coated pits. No modification of the time course of ¹²⁵I-EGF internalization was noted in the control and in the treated cells, but a different distribution of the labeling in the subcellular compartment was observed in treated cells. In 1.25(OH)₂D₃-treated batches, the grain density remained low in the receptosomes throughout the experiment, whereas it was high and occurred early in the lysosomes. On the other hand, in control cells, the grain density of the receptosomes was high, whereas it occurred late and was relatively low in the lysosomes. These data suggest that 1.25(OH)₂D₃ is a regulator of EGF-R level in BT-20 cell line, but it cannot be affirmed whether this effect is direct or mediated by other parameters.     

Online monitoring of yeast cultivation using a fuel-cell-type activity sensor

A microbial fuel-cell type activity sensor integrated into 500 mL and 3.2 L bioreactors was employed for ampero- (μA) and potentiometric (mV) measurements. The aim was to follow the microbial activity during ethanol production by Saccharomyces cerevisiae and to detect the end of carbohydrate consumption. Three different sensor setups were tested to record electrochemical signals produced by the metabolism of glucose and fructose (1:1) online. In a first setup, a reference electrode was used to record the potentiometric values, which rose from 0.26 to 0.5 V in about 10 h during the growth phase. In a second setup, a combination of ampero- and pseudo-potentiometric measurements delivered a maximum voltage of 35 mV. In this arrangement, the pseudo-potentiometric signal changed in a manner that was directly proportional to the amperometric signals, which reached a maximum value of 32 μA. In a third type of arrangement, a reference electrode was added to the anodic bioreactor compartment to carry out ampero- and potentiometric measurements; this is made possible by the high internal resistance of the cultivation. In this case, the reference potential rose to 0.44 V while the current maximum recorded by the working electrodes reached 27 μA. Reference and pseudo-reference electrodes were in all cases K₃Fe(CN)₆/carbon. Electrodes were made of 9 cm² woven graphite. To compare the electrochemical signals with established values, the metabolism was also monitored for optical density (at 600 nm) indicating biomass production. For fructose and glucose conversion, HPLC with an Aminex column and RI detector was used, and ethanol production was analyzed by GC with methanol as internal standard. The combination of amperometric and potentiometric recordings was found to be an ideal setup and was successfully used in reproducible cultivations.     

Etablissement des relations de dominance-soumission chez les bovins domestiques III. Effet de l'expérience sociale

An evaluation of social experience in the establishment of dominance-submission relationships was attempted using 20 animals in various constellations of 4. The establishment of rank-order in 5 groups of inexperienced heifers upon their first contact with strangers was compared with that in 20 groups consisting of the same animals in different arrangements upon their second to their fifth encounter with strangers. With experience, the various types of agonistic interactions were differently utilized, contact-forming and fighting time were reduced, the social order was more rapidly and firmly established, and fighting often dispensed with.