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.     

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.     

Affinity requirements for induction of sequential phases of human B cell activation by membrane IgM-cross-linking ligands

The affinity of Ag interaction with a B cell's membrane IgM (mIgM) receptors has long been considered to play a critical role in the in vivo clonal selection of B lymphocytes. This study has examined a possible basis for this affinity selection at the level of Ag induction of sequential B cell activation phenomena, i.e., elevated membrane class II MHC expression (G0* excitation), G1 entry, and S phase entry. Functional experiments with model bivalent Ag, i.e., a group of murine mAb of diverse intrinsic binding affinities for human IgM, revealed that the minimal affinity requisites for inducing the above phenomena vary significantly. At a ligand concentration of 100 micrograms/ml, the induction of increased class II MHC expression, G1 entry, and S phase had minimal affinity thresholds of Ka approximately 0.2 to 2 x 10(6) M-1; approximately 7 x 10(6) M-1; and approximately 1 x 10(8) M-1, respectively. Pulsing studies revealed that whereas high affinity ligand was essential at later periods in the prolonged (greater than 24 h) signaling period that leads to S phase entry, mAb with significantly lower affinity were competent at signaling during the first 24 h. Because all but the lowest affinity ligand (Ka = 2 x 10(5) M-1) could effectively modulate mIgM, and furthermore, because B cells show a substantial increase in surface area during activation, it appears likely that one factor contributing to the higher affinity requirements for induction of late activation phenomena is a progressive decrease in the density of mIgM on the responsive B cells. These studies suggest that whereas only a small proportion of B cells, i.e., those with relatively high affinity for an antigenic epitope, will be triggered to clonally expand on encountering a paucivalent Ag in the absence of T cell help, a much wider spectrum of the B cell repertoire will be triggered to a state of partial activation. How the presence of ancillary T cells and cytokines may facilitate the full clonal expansion of these latter cells is discussed.     

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.     

Phytoplankton composition and spatial distribution of copper and zinc in the Fal Estuary (Cornwall,UK)

In the estuaries near Falmouth (Cornwall, UK) levels of dissolved copper and zinc are high, due to drainage of copper and tin mines. Phytoplankton species composition in the autumn of 1989 deviated in the metal-contaminated Restronguet Creek from that in other estuarine branches,viz. Fal, Tresillian and Percuil. In the riverine part of Restronguet Creek (Carnon River)Euglena mutabilis, known as an acidophilic (pH 3) metal-resistant flagellate, occurred at micromolar Cu and Zn, whereas in the clean riversChlamydomonas sp. andOocystis sp. occurred at nanomolar Cu and Zn. An ordination analysis revealed the following patterns in Cu, Zn and phytoplankton species composition in the poly- and euhaline waters. Seston-bound Zn and dissolved Zn were in equilibrium,Katodinium rotundatum is Zn-tolerant, andSkeletonema costatum occurred in water with high contents of Cu in seston. However, none of the variables in these patterns correlated at a significant level (p>0.05). The results show that algae-metal interactions are complicated, and that statistical correlations foundin situ need experimental verification.Communication no. 542 of the Delta Institute for Hydrobiological Research.     

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.     

The effects of unilateral antennectomy on the flight behaviour of male Heliothis virescens in a pheromone plume

Abstract .Unilaterally antennectomized Heliothis virescens (F.) males flying close to the central axis of a plume of sex pheromone display no significant differences in behaviour compared to sham-operated males in course angles, track angles, airspeed and groundspeed. This demonstrates that right/left antennal information is not necessary for normal orientation movements in response to pheromone, but rather that it is 'blended' within the moth's central nervous system before pheromone-mediated manoeuvres are made. However, some unilaterally antennectomized moths (36%) make repetitive, asymmetrical, saw-tooth-shaped tracks during pheromone-mediated upwind progress, whereas control moths never make such tracks. Unilaterally antennectomized moths made such tracks on the side of the plume contralateral to the missing antenna. We hypothesize that these occasional asymmetrical tracks in unilaterally ablated males are the result of reiterative asymmetrical pheromone stimulation of a higher probability on track legs going toward rather than away from the long axis of the plume on males with a single antenna remaining on the 'away from axis' side. Combined with a greater propensity for treated moths to lock onto the plume away from the central axis on one side rather than the other, repetitive successive asymmetrical track legs (resulting in a saw-tooth-shaped track) are commonly observed in these moths. Control moths do also make asymmetric successive track legs but they rarely are repeated and thus are not readily observed.     

Accurate determination of mean cell volume by isotope dilution in erythrocyte populations with variable deformability.

Variations in erythrocyte deformability and morphology lead to artifacts in electronic determinations of mean cellular volume (MCV) by the aperture-impedance method. The micropipette-aspiration technique loses accuracy when applied to severely aberrant cells such as dense sickle cells. A new light-scattering technique requires that the cells be capable of undergoing isovolumetric sphering. In contrast, the isotope-dilution (ID) method measures absolute mean volume and is free of artifacts associated with abnormal deformability or morphology. It does not depend on any algorithms or correction factors and does not subject the cells to any stringent processing, not even centrifugation. The ID method can be used to determine the mean volume of red cells in hypo- or hypertonic media or in the presence of pharmacologic agents. It requires no more than a 1-ml aliquot of suspended cells at a hematocrit of at least 30%. The cells can be readily recovered, washed, and reused. Using EDTA labeled with 57Co as an extracellular space marker we have used ID to determine the MCV of fractionated normal human red blood cells (RBC), unfractionated RBC containing SS hemoglobin, and RBC from four other mammalian species. In the case of human RBC obtained from eight normal donors, we obtained mean MCV values (+/- SD) of 83.6 +/- 3.0, 87.5 +/- 3.9, and 76.5 +/- 5.3 fl for unfractionated and top and bottom 10% density fractions, respectively. The value 83.6 is significantly lower than the generally accepted range of 89-91 indicated by electronic analyzers calibrated against spun microhematocrits. The discrepancy of about 7% can account for the difference between mean cell hemoglobin concentration (MCHC) data determined by a calibrated Coulter Counter and corresponding data obtained with paired samples using a cyanmethemoglobin procedure specified in NCCLS Standard H15-A and corrected for trapped plasma.     

Development and evaluation of the polymerase chain reaction to detect Mycoplasma genitalium

The polymerase chain reaction (PCR) was developed to detect Mycoplasma genitalium. Oligonucleotide primers were used to amplify a 374 bp region of the attachment protein of the mycoplasma. DNA from three strains of M. genitalium tested gave a characteristic PCR product which was not seen with DNA from any other source. As little as 10(-15) g of M. genitalium DNA could be detected and it was found in the vagina of progesterone-treated BALB/c mice inoculated with M. genitalium organisms later than they could be cultured from this site, but not in mice that never became colonised vaginally.