Preliminary study on the effect of temperature on the transport of thyroxine (T4) into the body tissues and sub-cellular fractions of liver and muscle of carp, Cyprinus carpio

In order to determine if the inability of thyroxine to induce cellular effects at low temperature is mediated through a temperature-sensitive system for the translocation of T4 into the nucleus, the effect of temperature on the uptake of T4 by body tissues and sub-cellular fractions of carp liver and muscle was studied in vivo. A single injection of 125I-T4 (1 micro C/10 g body weight) was given intraperitoneally to juvenile carp maintained at 15 and 25 C. Uptake from the peritoneal cavity was rapid. All the tissues exhibited maximum radioactivity at 2 hour after the injection. Fish kept at 25 C showed another peak at 8 hour and those at 15 C at 48 hour after the single injection. Transfer of T4 from the cytoplasm to nuclei was not blocked at lower temperatures. For example, in liver at 8 hour, nuclei from fish tissues kept at lower or higher temperatures had equal amounts of radioactivity. Muscle nuclei had 15% more radioactivity than liver nuclei when expressed as radioactivity/g tissue. Since there are comparable amounts of activity in the nuclei at both temperatures, some other mechanism/s than a simple block in transport from cytoplasm to nuclei is operating. There are some indications that nutritional status of fish may be playing some role in this respect.     

Microspectrophotometric and scanning microphotometric studies of carp (Cyprinus carpio L.) erythrocytes

Carp (Cyprinus carpio) hemoglobin readily autoxidizes in blood smears. Quantification of Soret-band absorbance in individual erythrocytes by means of scanning cytophotometry therefore requires more elaborate methods of preparation of blood samples. Of the fixatives that have been tested, suspension of whole blood in isotonic salt solutions containing glutaraldehyde was most suitable. Glutaraldehyde-fixed red blood cells are totally resistant to hemolysis. In the course of fixation, hemoglobin is transformed to methemoglobin. Spectrophotometry indicated extensive similarities between glutaraldehyde-fixed carp methemoglobin and human methemoglobin. In aqueous solutions, the intensity of the Soret-peak was pH-dependent. The allosteric modifier organic polyphosphate caused an R----T transition, resulting in increased molar extinctions. Dried preparations showed Soret-spectra that were not influenced from either pH or organic polyphosphate concentration of the aqueous suspensions in which the erythrocytes had been stored. The same was true for slide preparations of cyanomethemoglobin, easily derived from methemoglobin on addition of potassium cyanide. In the absence of oxygen fresh blood cells from carp slowly transform their hemoglobin into deoxyhemoglobin. Spectra of the intermediate stages of deoxygenation, Hb4(O2)3, Hb4(O2)2 and Hb4(O2), as well as mixtures of these intermediates, could be monitored.     

Utilization of poly-β-hydroxybutyrate in free-living cultures of Rhizobium ORS571

Abstract The effect of carbon starvation on growth and poly-β-hydroxybutyrate (PHB) utilization in oxygen-limited chemostat cultures of Rhizobium ORS571 was studied. Under oxygen-limited growth conditions PHB was not degraded. When in a nitrogen-fixing oxygen-limited culture, after stopping the medium supply, the dissolved oxygen concentration was maintained at 10 μM, a slow breakdown of PHB was observed. Addition of ammonia and air to a nitrogen-fixing oxygen-limited culture after the medium supply had been stopped, resulted in the simultaneous utilization of PHB and succinate. The possible use of the energy derived from PHB degradation in Rhizobia bacteria and bacteroids is discussed.     

Sex Differences in the Steepness of Dominance Hierarchies in Captive Bonobo Groups

Bonobos have a reputation as a female-dominated and egalitarian species. We examined the 2 aspects of dominance in 6 captive bonobo groups. Females do not consistently evoke submission from all males in all contexts. Though females occupy the highest-ranking positions in the dominance hierarchy, there are in each group males that obtain rather high ranks and are able to dominate ≥1 female. Thus female dominance is not complete and hierarchies can be better described as nonexclusive female dominance. We studied egalitarianism by measuring linearity and steepness of dominance hierarchies. The hierarchies of all groups are highly linear. Hierarchies among males are steeper than among females. On average, male bonobos are more despotic than females, but females too can have despotic relations, both with other females and with males. Hence one can call bonobos in captivity semidespotic rather than egalitarian.