Influence of fish size on proliferation and differentiation of cultured myosatellite cells of white axial muscle of carp (Cyprinus carpio L.)

Abstract. The in vitro proliferation [uptake of 5-bromo-2'-deoxyuridine (BrdU)] and the degree of differentiation (presence of desmin) of myosatellite cells isolated from white axial muscle of carp between 3 cm and 27 cm standard length (SL) were examined 17 h after isolation. The fraction of the myosatellite cells that were both desmin positive and BrdU positive never exceeded 2% of the total number of isolated myosatellite cells, irrespective of the standard length of the donor(s). This indicates that, for carp, the temporal relationship between replication and desmin expression of myosatellite cells is different from that described for myogenic cells of mammals and birds. The percentage of BrdU positive myosatellite cells was significantly correlated with standard length: it increased from 10% for carp of about 5 cm SL to 40–50% for carp between 20 cm and 27 cm SL. The percentage of desmin positive myosatellite cells was about 50–60%; it was not significantly correlated with standard length. The percentage of myosatellite cells that were both BrdU negative and desmin negative showed a stepwise difference in this percentage with increasing length. Fish smaller than 10 cm SL, had more of these cells (10–40%), than larger fish (which had 0–12%). So, apparently the composition of the myosatellite cell population changes during growth. The low percentage of proliferating cells, and the relatively high percentage of differentiated (desmin positive) myosatellite cells obtained from 3–6 cm large carp, suggests that, in these small fish, muscle growth strongly depends on the use of a pool of myogenic cells that has been formed at an earlier stage of their development.     

Model of mammalian cell reproductive death I. Basic assumptions and general equations

A systemic model describing the major radiobiological effects of various types of radiation is proposed. The model base lines were substantiated, and general mathematical equations for cell survival developed. The model takes into consideration such physical and biological factors as linear energy transfer, ion track structure, and structural and functional organization of interphase chromatin. This paper presents the basic assumptions made and general equations for the cell killing.     

Alterations in the hepatic enzymes following experimental lead poisoning

An investigation on the influence of lead toxicity on some of the hepatic enzymes was studied in rats both after a shorter interval of 15 d and after longer intervals of 60 and 90 d. Three different doses of lead as 5, 10, and 50 mg/kg body wt were administered orally on every alternate day. Whereas significant inhibition of succinic dehydrogenase was seen following lead poisoning, the activity acid and alkaline phosphatase increased with lead intoxication. The histoarchitecture of the liver was grossly intact. Liver accumulated less lead compared to kidney at 60 and 90 d.     

Alloreactive lymphocytes from T cell receptor (beta-chain) transgenic mice do not mediate a graft-versus-host reaction.

The injection of mature T cells into a tolerant or immunocompromised allogeneic host animal produces a graft versus host response (GVHR) that can result in splenomegaly, immunosuppression and death of the host animal. We demonstrate here that lymphocytes from T cell receptor beta-chain (TCR-beta) transgenic mice, in which the expression of the transgene inhibits endogenous beta- and gamma-gene rearrangements and thus causes abnormal T cell development, are unable to mediate a GVHR. The GVHR was measured after the injection of lymphocytes from transgenic mice into normal F1 mice and also after transplantation of bone marrow and lymphocytes from transgenic mice into lethally irradiated F1 recipients. In both systems, cells from transgenic mice failed to produce a significant GVHR. Cells from the transgenic mice were able to recognize the foreign histocompatibility Ag of the host in vitro and in vivo although the transgenic mice rejected skin grafts more slowly than controls. Thus, lymphocytes from transgenic mice were unable to produce a GVHR despite the presence of alloreactive T cells. These results suggest that lymphocytes from TCR-beta transgenic mice fail to mediate a GVHR either because lymphocytes with a single transgenic TCR-beta chain have a limited ability to recognize allogeneic cells in vivo or because the transgenic mice lack lymphocyte subsets that are important for the mediation of a GVHR.     

Variations in thymocyte susceptibility to clonal deletion during ontogeny. Implications for neonatal tolerance.

Activation of immature thymocytes via the TCR results in programmed cell death and clonal deletion. We have examined thymocytes from mice of different ages and observed that, whereas TCR-mediated signaling caused deletion of thymocytes from newborn and 3-week-old mice, it failed to delete thymocytes from mice of 1 week of age. This could not be attributed to differences in cell surface TCR expression, TCR-mediated phosphoinositide hydrolysis or Ca2+ mobilization, or total cellular levels of TCR zeta- and eta-chains. Moreover, thymocytes of all ages were equally susceptible to corticosteroid- and Ca2+ ionophore-induced programmed cell death. These data are consistent with the notion that fetal and neonatal thymocytes represent a relatively synchronous wave of cells passing through phases in which they are susceptible and then resistant to TCR-induced programmed cell death. They also support the notion that the classical phenomenon of neonatal tolerance is due to clonal deletion and that the inability of allogeneic cells to tolerize mice at 1 week of age is because the thymocytes are refractory to TCR-alpha beta-mediated clonal deletion.     

Body temperatures of Namib Desert tenebrionid beetles: their relationship in laboratory and field

Abstract The body temperatures of six apterous species of Namib Desert tenebrionid beetles were measured continuously with indwelling thermocouples under laboratory conditions and in the field. The range of body temperatures selected was within the upper half of their 'tolerated range', which we defined as the temperatures lying between measured critical thermal maximum and critical thermal minimum. In the field, individuals also maintained their body temperatures within the upper half of the 'tolerated range'. These beetles maintained higher body temperatures than those recorded for any other ectothermic insect. Three of the six species maintained lower body temperatures in the field than they selected in the laboratory. The other three species showed no significant difference between field and laboratory body temperatures. We conclude that these beetles are not forced by biotic or abiotic factors to adopt thermal niches which present them with physiological difficulties.     

A structural protein that plays an enzymatic role in the eggshell of Drosophila melanogaster

E.S.P. is responsible for the hardening process of the egg-shell at the end of oogenesis (stage 14B) and constitutes a structural component. By immunoblotting, using polyclonal rabbit anti-HRP antibody and anti-rabbit IgG-HRP or Protein A-1251 as second antibody, one major band with MW 38KD on nitrocellulose filter showed positive reaction. We conclude that the E.S.P. is identical to the S38 chorionic protein. Morphological immunogold staining, using pre-embedding procedure, revealed positive reaction in the innermost chorionic layer (ICL) and the endochorion of the eggshell. In addition, electron probe X-ray microanalysis revealed the existence of 37% calcium (explained since the enzyme is Ca2(+)-activated) and 5% iron (explained due to the fact that it is a haemoprotein).     

Phospholipase A2 activity in human platelets. Isolation and purification of the enzyme

The activity of phospholipase A2 in blood platelets of healthy donors and IHD patients was examined. The enzyme activity was found to be increased 3-fold in platelets possessing a high level of functional activity (IHD) and by one order of magnitude in patients with myocardial infarction as compared with healthy donors. An enzyme preparation possessing a phospholipase activity was isolated from platelets by using salt extraction (KCl) and sonication. Purification of the enzyme by affinity chromatography resulted in two protein peaks both having a phospholipase A2 activity, the purification and molecular masses of these fractions being 768- and 2200-fold, and 13.5 and 15 kDa, respectively. It was supposed that these proteins are substrate-specific forms of phospholipase A2.