Growth-promoting effects of acidic and basic fibroblast growth factor on rabbit articular chondrocytes aging in culture

Rabbit articular chondrocytes have a limited growth potential in vitro. After four passages in culture, chondrocytes have accomplished more than 50% of their life span. At this stage of culture, they are considered to be senescent-like, since a dramatic decrease in proliferative capacity and enhanced cell size and protein content are observed. These aged cells are, however, still able to respond to fibroblast growth factor (FGF). The addition of either acidic or basic FGF (10 ng/ml) to culture medium permitted an enhanced proliferation. The attenuation of FGF mitogenic activity during aging was not observed for both fractions. Moreover, when treated with acidic or basic FGF, aged chondrocytes had a smaller size and a lower protein content. The acidic FGF was less potent than the basic FGF in delaying the evolution of aged chondrocytes to senescence.     

Response of resident murine peritoneal macrophages to in vivo administration of granulocyte-macrophage colony-stimulating factor

The effect of s.c. inoculation of purified recombinant derived granulocyte-macrophage (GM)-CSF on resident murine peritoneal macrophages was assessed in this study. From 18 to 24 h after s.c. administration of GM-CSF to normal mice, the resident peritoneal macrophages were harvested and the levels of membrane-bound IL-1, FcR, Mac-1 cell-surface Ag, and class II MHC expression were assessed. Peritoneal cells from GM-CSF-inoculated mice had significantly greater levels of membrane-bound IL-1 than did control mice. In addition when resident peritoneal macrophages from normal mice were purified by adherence and grown in the presence of GM-CSF, they produced greater levels of both membrane-bound and secreted IL-1. The peritoneal cells from GM-CSF-inoculated mice did not differ from controls in the expression of class II MHC-encoded Ag. This observation was confirmed by the finding that GM-CSF was unable to induce class II MHC expression on P388D1 cells, whereas a secondary mixed leukocyte culture supernatant was. Peritoneal cells from GM-CSF-inoculated mice also exhibited greater levels of expression of FcR and the Mac-1 cell-surface Ag. This resulted in an increase in their ability to phagocytose opsonized SRBC in vitro.     

Structural organization of the beta-globin locus of B-haplotype sheep

Goats and some sheep synthesize a juvenile hemoglobin, Hb C (alpha 2 beta C2), at birth and produce this hemoglobin exclusively during severe anemia. Sheep that synthesize this juvenile hemoglobin are of the A haplotype. Other sheep, belonging to a separate group, the B haplotype, do not synthesize hemoglobin C and during anemia continue to produce their adult hemoglobin. To understand the basis for this difference we have determined the structural organization of the beta- globin locus of B-type sheep by constructing and isolating overlapping genomic clones. These clones have allowed us to establish the linkage map 5' epsilon I-epsilon II-psi beta I-beta B-epsilon III-epsilon IV- psi beta II-beta F3' in this haplotype. Thus, B sheep lack four genes, including the BC gene, and have only eight genes, compared with the 12 found in the goat globin locus. The goat beta-globin locus is as follows: 5' epsilon I-epsilon II-psi beta X-beta C-epsilon III-epsilon IV-psi beta Z-beta A-epsilon V-epsilon VI-psi beta Y-beta F3'. Southern blot analysis of A-type sheep reveals that these animals have a beta- globin locus similar to that of goat, i.e., 12 globin genes. Thus, the beta-globin locus of B-haplotype sheep resembles that of cows and may have retained the duplicated locus of the ancestor of cows and sheep. Alternatively, the B-sheep locus arrangement may be the result of a deletion of a four-gene set from the triplicated locus.      

GM-CSF administration augments the survival of ity-resistant A/J mice, but not ity-susceptible C57BL/6 mice, to a lethal challenge with Salmonella typhimurium

Ity resistant A/J mice were challenged with a lethal dose (2 x 10(3) organisms) of Salmonella typhimurium. Infected mice treated with 1 microgram of GM-CSF twice daily showed increased median survival time and had a higher survival fraction than untreated controls. GM-CSF was most effective when given for a brief period (1 to 2 days) after infection. Pretreatment of the mice or delayed treatment with GM-CSF had no effect on the survival of the mice. Studies on the effect of GM-CSF on the bacterial load showed that mice treated with GM-CSF had fewer S. typhimurium in the spleen and peritoneal cavity on day 4 but not on day 2 after infection. GM-CSF treatment of ity-susceptible C57BL/6 mice infected with 10 organisms had no therapeutic effect.     

INDIVIDUALITY IN THE VOICE OF FUR SEAL FEMALES: AN ANALYSIS STUDY OF THE PUP ATTRACTION CALL IN ARCTOCEPHALUS TROPICALIS

Like most otariids species, the Subantarctic fur seal breeds on land in large, dense colonies. Pups are confronted by the long and repetitive absences of their mother throughout lactation. At each mother's return, pups have to find her among several hundreds of congeners. This recognition process mainly relies on acoustic signals. We performed an acoustic analysis on 125 calls from 20 females recorded during the 1999–2000 breeding season on Amsterdam Island (Indian Ocean). Ten variables were measured in both temporal and frequency domains. To find the acoustic parameters supporting individual signature, we assessed the differences between individuals using Kruskall-Wallis univariate analysis of variance. For each variable, we also calculated the potential of individuality coding (PIC) as the ratio between the between-individual coefficient of variation and the mean value of the within-individual coefficients of variation. We found that the frequency spectrum, the characteristics of the frequency modulation of the initial and middle part of the call and the call duration exhibit an important individual stereotypy (PIC values ranging between 1.5 and 3), whereas features relative to amplitude and the frequency modulation of the final part of the call are weakly individualized (PIC values between 1 and 1.2).     

Les ostracodes neogenes du bassin de Savigne-sur-Lathan(Faluns de Touraine) I. Biostratigraphie et paleoecologie

The Neogen formations from the basin of Savigné-su-Lathan (Indre-et-Loire) have yielded 53 species of ostracods.The connections with the best known fauna from the Aquitaine basin and the Rhône basin are discussed.     

Modulation of adenylate cyclase/cyclic AMP response by thyrotropin and prostaglandin E2 in cultured thyroid cells. 1. Negative regulation.

Isolated porcine thyroid cells, cultured in the presence of thyrotropin (greater than or equal to 0.25 mU/ml) or prostaglandin E2 (greater than or equal to 0.1 micron), showed decreased adenosine 3':5'-monophosphate (cyclic AMP) response to further thyrotropin or prostaglandin E2 stimulation, respectively. Kinetics of the refractory process to thyrotropin and prostaglandin E2 are different: (a) maximal refractoriness to prostaglandin E2 was attained after 2--6 h exposure to prostaglandin E2 while refractoriness to thyrotropin was maximal only after 12--24 h; (b) the degree of refractoriness to prostaglandin E2 was much greater than that to thyrotropin. Refractoriness to thyrotropin or prostaglandin E2 is characterized: by specificity for each thyroid stimulator; by dependence upon the dose of thyrotropin or prostaglandin E2 in culture, e.g. induction of high degree of refractoriness with 0.5 mU/ml thyrotropin (or 1 micron prostaglandin E2), which elicits only a small cyclic AMP increase; by time requirement for induction; by partial effect; by changes of maximum activation of cyclic AMP response; by reversibility. This refractoriness of the cyclic AMP response was not induced by dibutyryl adenosine 3':5'-monophosphate. It was not attributed to increased cyclic AMP-phosphodiesterase activity, but to alterations in the receptor-adenylate cyclase system. Prevention of refractoriness to thyrotropin or prostaglandin E2 by incubation of cells in the presence of actinomycin D, puromycin and cycloheximide suggests that new RNA and protein syntheses are required for the development of the refractory state.     

Decoding the mechanisms of gait generation in salamanders by combining neurobiology, modeling and robotics

Vertebrate animals exhibit impressive locomotor skills. These locomotor skills are due to the complex interactions between the environment, the musculo-skeletal system and the central nervous system, in particular the spinal locomotor circuits. We are interested in decoding these interactions in the salamander, a key animal from an evolutionary point of view. It exhibits both swimming and stepping gaits and is faced with the problem of producing efficient propulsive forces using the same musculo-skeletal system in two environments with significant physical differences in density, viscosity and gravitational load. Yet its nervous system remains comparatively simple. Our approach is based on a combination of neurophysiological experiments, numerical modeling at different levels of abstraction, and robotic validation using an amphibious salamander-like robot. This article reviews the current state of our knowledge on salamander locomotion control, and presents how our approach has allowed us to obtain a first conceptual model of the salamander spinal locomotor networks. The model suggests that the salamander locomotor circuit can be seen as a lamprey-like circuit controlling axial movements of the trunk and tail, extended by specialized oscillatory centers controlling limb movements. The interplay between the two types of circuits determines the mode of locomotion under the influence of sensory feedback and descending drive, with stepping gaits at low drive, and swimming at high drive.