Development and use of microsatellite DNA loci for genetic ecotoxicological studies of the fathead minnow (Pimephales promelas)

The development of new DNA technologies has increased the opportunities to study the effect of genetic variation as a factor in selection, resistance, and fitness of individuals and populations. Genetic composition affects the evolutionary potential of an organism; however, whether genetic variation has a role in adaptation and survival due to chemical stress is still under debate. The strategy of measuring such variation should be based on the desired number of loci needed and degree of polymorphism at each locus. Microsatellite DNA loci (also known as Simple Tandem Repeats, STRs) have among the highest levels of variation within most eukaryotic genomes. Methods to determine the high levels of variation in individuals and populations have become more refined, making DNA-based studies in ecotoxicology more feasible. Herein, we describe the general characteristics of microsatellite DNA loci, their isolation, and their applications to toxicological studies using the fathead minnow (Pimephales promelas) as a focal species.

In vitro generation of Epstein-Barr virus-specific cytotoxic T cells in patients receiving haplo-identical allogeneic stem cell transplantation

Use of a partially mismatched related donor (PMRD) is an option for patients who require allogeneic transplantation but do not have a matched sibling or unrelated donor. Epstein-Barr virus (EBV)-induced lymphoma is a major cause of mortality after PMRD transplantation. In this study, we present a clinical grade culture system for donor-derived EBV-specific cytotoxic T cells (CTLs) that do not recognize haplo-identical recipient cells. The EBV-specific CTLs were tested for cytolytic specificity and other functional properties, including ability to transgress into tissues, propensity for apoptosis, degree of clonality, stability of dominant T-cell clones, and Tc and Th phenotypes. The EBV-specific CTLs were routinely expanded to greater than 80 x 10(6) over a period of 5 weeks, which is sufficient for clinical application. A CD8+ phenotype predominated, and the CTLs were highly specific for donor lymphoblastoid cell lines (LCLs) without killing of recipient targets or K562. Vbeta spectratyping showed an oligoclonal population that was stable on prolonged culture. The EBV-specific CTLs were activated (D-related human leukocyte antigen [HLA-DR+], L-selectin+/-) and of memory phenotype (CD45RO+). Expression of the integrin VLA-4 suggested that these CTLs could adhere to endothelium and migrate into tissues. The Bcl-2 message was upregulated, which may protect the CTLs from the apoptosis. The first demonstration of overexpression of bcl-2 in human memory CTLs. In addition, we show that lymphoblastoid cell lines used to generate CTLs are readily genetically modified with recombinant lentivirus, indicating that genetically engineered antigen presentation is feasible.

Codominant and recessive 9-beta-D-arabinofuranosyladenine-resistant mutations of baby hamster cells

9-beta-D-Arabinosyladenine (araA)-resistant mutants of baby hamster kidney (BHK) cells can be classified into 3 classes. In order to gain a better understanding of the mechanism(s) of resistance and the biochemical basis of cytotoxicity of various purine nucleosides, cell hybrids of the mutant and wild-type cells were made and analyzed. The class I araA-resistant, adenosine-kinase-deficient (AK-) allele was shown to be recessive to the wild-type araA-sensitive (AK+) gene. The class II mutant allele, which encodes an altered ribonucleoside diphosphate reductase, was shown to be codominant. The class III mutants show multiple phenotypes, araAr/dAdor/adenosine sensitive (Ados) and alteration in AK activity. The araA- and dAdo-resistant alleles of araS10d, ara-16c, and ara-19a in class III mutant/wild-type hybrid cells are all recessive to the wild-type allele, consistent with a common mechanism of resistance. In contrast the Ados allele of ara-S10d is dominant while those of ara-16c and ara-19a are recessive. The difference may be a reflection of two distinct mechanisms of enhanced Ado sensitivity or, alternatively, it suggests that the sensitivity of the hybrids to Ado is highly dependent on the level of AK activity.

An adenosine kinase mutation in baby hamster kidney cells causing increased sensitivity to adenosine

A class of arabinosyladenine (araA)-resistant mutants of baby hamster kidney (BHK 21/C13) cells exhibits multiple phenotypes: resistance to araA and deoxyadenosine, extreme sensitivity to adenosine (Ado) and varying degrees of deficiency in adenosine kinase (AK) activity. One of these Ados/araAr strains, ara-S10d, was isolated without mutagenesis and was shown to possess about 59% level of the wild-type AK activity. The AK from ara-S10d had an altered Km and pH optimum and was stimulated by K+ cations. A number of Ados to Ador revertants were isolated from ara-S10d, and in all of the 7 examined, the AK activity was reduced to a nondetectable level. The altered kinetic parameters of the AK enzyme in ara-S10d cells suggest a mutation of the AK gene that leads to the synthesis of an altered enzyme. The loss of AK activity in the Ador revertants suggests an association of the enhanced Ado sensitivity to the AK mutation.

Differentiation properties of pure populations of human dystrophic muscle cells

The interpretation of the majority of studies of Duchenne muscular dystrophy (DMD) has been complicated by the heterogeneous composition of the cultures used. In addition to muscle cells, muscle tissue contains adipocytes and fibroblasts and the proportion of these cell types varies, especially in disease states. To overcome this problem we developed culture conditions which permitted isolation and characterization of pure populations of clonally derived human muscle cells [1, 2]. Here we report the successful application of these methods to muscle cells from biopsies of individuals with diagnosed DMD. The normal and mutant human muscle cells were used in experiments of muscle differentiation in the same manner as cell lines. Frozen-stored cells were thawed, plated in a series of replicate plates, and allowed to differentiate under similar culture conditions. Yet, in contrast with cell lines, the cells were karyotypically normal, not altered by adaptation to long-term culture, and had a finite lifespan. We have systematically analysed specific properties of the normal and DMD muscle cells which differentiated in culture. The kinetics and extent of myoblast fusion, myotube morphology, and the accumulation and distribution of membrane acetylcholine receptors were monitored. In addition, the isozyme composition of creatine kinase and its intracellular and extracellular distribution were determined. Our results indicate that DMD muscle cells are fully capable of initiating myogenesis in culture and do not differ from normal muscle in several important parameters of differentiation.

Mutator genes of baby hamster kidney cells

Two mutator genes of mammalian cells were demonstrated. One was associated with the ribonucleoside diphosphate reductase, and the other was associated with an extreme adenosine sensitivity.

Semi-conservative and non-conservative replication of DNA in temperature-sensitive mouse L-cells

The mode of DNA replication has been studied in wild-type mouse L-cells (WT-4) and in two subclones (TS A1S9 and ts C1 cells) which are temperature-sensitive in DNA synthesis. It has been demonstrated that DNA is replicated by the semi-conservative mechanism in WT-4 cells grown at 34 degrees C or at 38.5 degrees C throughout the logarithmic phase and into the stationary phase. Similar results were obtained with ts A1S9 and ts C1 cells grown at the permissive temperature (34 degrees C). When the latter cells were incubated at the non-permissive temperature (38.5 degrees C) inactivation of DNA synthesis appeared to proceed through three general stages. During the first 24 h after temperature upshift suppression of semi-conservative DNA replication occurred. During the second stage a very low level of semi-conservative synthesis was maintained. During the third stage, incorporation of dThd into DNA began to increase, often reaching 10-20% of control levels after 3-5 days. During this third stage DNA synthesis was effected by a non-conservative mechanism. Temperature-inactivated ts A1S9 cells and ts C1 cells were able to perform semi-conservative synthesis upon back-shift to 34 degrees C, using as template that DNA synthesized prior to temperature upshift.