Comptes rendus des seances de l'Academie des sciences. Serie III, Sciences de la vie最新文献

Variations in the plasma concentrations of testosterone (T) and delta 4-androstenedione (delta 4) levels were measured by radioimmunoassay in individual young Hubbard Chickens from the age of 16 days until 100 days. Plasma testosterone was low and remained relatively stable between days 16 and 63 (0.10 to 0.30 ng/ml), but increased then rapidly (0.32 +/- 0.07 ng/ml on day 65 vs. 1.49 +/- 0.27 ng/ml on day 100). During the same period delta 4 levels increased too (0.23 +/- 0.06 ng/ml on day 65 vs. 0.75 +/- 0.18 ng/ml on day 100). During the first weeks of life, delta 4-androstenedione prevailed over testosterone. The [delta 4]/[T] ratio reached a maximum between days 30 and 40 and was then reversed to negative values. Results are discussed in relation to those obtained for Chicken from other stocks.

Relations between respiration rates and temperature for 5 young Vipers previously maintained under natural climatic conditions were analysed from 15 to 30 degrees C. Oxygen consumption increases with temperature and concurrently with a constant Q10, at least for medium consumption, and drops as spontaneous activity is higher.

The genetic code can be considered as degenerated from a minimal cyclic code, whose maximal chain is given. We study the relation of this code with the cyclic code corresponding to the 64 triplets. Finally we compare the minimal code to that obtained from a binary cyclic code.

One injection of ovine growth hormone (1.27 X 10(-5) USP units/g body weight) determines in the Eel, 1 day later, a twofold decrease in plasma thyroxine level as well as a twofold increase in plasma triiodothyronine level. These modifications of circulating iodothyronine levels result from a considerable stimulation of the peripheral deiodination of thyroxine to triiodothyronine, shown by a kinetic study of labelled thyroxine metabolism. The increase of production of metabolically active hormone, triiodothyronine, induced by growth hormone could represent the (or one of the) mechanism(s) implicated in the synergic action of these two hormones on Vertebrate growth.

Adaptation of posture and of postural adjustments involved in voluntary elevation of the arm was studied during a seven day spaceflight. Results show an important forward inclination of the body at beginning of the flight. After three days in flight the position of the body was similar to the terrestrial posture. Together with this inclination, a redistribution of the electromyographic activities between flexor and extensor muscles of the ankle was observed. Anticipatory postural adjustments were always present in microgravity. These results are interpreted on the basis of body scheme.

Enumerating Bn numbers using only Bn figures is possible thanks to an overlapping reading of a cyclic sequence built according to Baudot's code. This code allows the genetic code to be screened to show the distribution of the synonyms of the aminoacids. The assignments of the genetic code obey strict laws of optimisation of resistance against the effects of mutations.

Pseudomonas testosteroni uses testosterone as sole source of carbon. We were able to isolate an extrachromosomal DNA from a strain of Pseudomonas testosteroni and to obtain Pseudomonas putida and aeruginosa and Escherichia coli transformants catabolizing testosterone.

Parathyrin of the corpuscles of Stannius (PCS), glands which are restricted to Holostei and Teleostei, resembles mammalian parathyroid hormone secreted by the parathyroids. These glands made their first phylogenic appearance with Amphibians, whereas the Stannius corpuscles disappeared. We have compared, in the clawed toad, Xenopus laevis, the effects of injections of extracts of corpuscles of Stannius and of the active synthetic fragment of parathyrin (1-34 hPTH). Both hormones elicited hypocalcemia and hypophosphatemia within a 4 days treatment. These results are interpreted according to the hypothesis that in the most primitive Amphibians there are receptors leading to hypocalcemic effect co-existing with the appearance of "new" glands which secrete a hypercalcemic hormone in mammals.

Chromosome studies were performed on 5 Ewing sarcoma cell lines. An identical reciprocal translocation t(11; 22) (q24; q12) was found in 4 cell lines established from 3 different tumors. These results, associated with those obtained at the same time and independently from fresh tumor cells, suggest that the translocation t(11; 22)(q24; q12) may be a chromosomal marker characteristic of Ewing sarcoma cells. This translocation involves the chromosome 22 on which the H-c-sis oncogene has been located; it could be used as a new tool for exploring the role of genetic transposition in the malignant cell transformation.

The physiological and pharmacological properties of septo-hippocampal neurons (identified through antidromic stimulation of the fimbria) were studied in the Rat under urethane anaesthesia. Half of these neurons (located in the medial septum and the nucleus of the diagonal band of Broca) displayed a rhythmic, bursting activity at about 4/s. A large majority of these neurons (bursting as well as non-bursting) could be excited through iontophoretic application of acetylcholine or carbachol.