The effect of acclimation temperature on enzyme activity in Drosophila melanogaster.

1. The response to thermal acclimation of five key rate-limiting enzymes of intermediary metabolism and of six degradative enzymes was measured in tissue extracts of adult Drosophila melanogaster which had been acclimated for 4 days to 15, 25 or 30 degrees C. 2.

Enzyme induction in recovering dauer larvae of the nematode Caenorhabditis elegans in response to increasing concentrations of food source in the recovery medium.

Exposure of recovering dauer larvae of Caenorhabditis elegans to increasing concentrations of Escherichia coli in the recovery medium produced dramatic increases in the enzymes of intermediary metabolism. There was no significant difference between the rates of development of recovering dauer larvae grown on different concentrations of E. coli.

Cell death via apoptosis and its relationship to growth, development and differentiation of both tumour and normal cells.

Cell death can occur by two possible mechanisms, necrosis or apoptosis. Necrosis is the classically recognised form of cell death and is characterised by high amplitude swelling of the mitochondria, nuclear flocculation and uncontrolled cell lysis. Tissue necrosis is normally seen following severe trauma to cells.

HL-60 cells induced to differentiate towards neutrophils subsequently die via apoptosis.

The human promyelocytic HL-60 cell line can be induced to differentiate to neutrophil-like cells in response to a variety of chemical stimuli. We have found that retinoic acid-treatment of HL-60 cells over a period of 6-8 days resulted in a progressive increase in the proportion of cells with mature neutrophil morphologies and was closely followed by an increase in the proportion of cells exhibiting the morphological characteristics of apoptosis, the non-pathological mode of cell death. Using Percoll step-density gradients we have demonstrated a marked increase in the buoyant density of these cells and have used this density difference to obtain enriched fractions of cells for more detailed study.

Selection of chloroplast mutants.

The chloroplast genome encodes a number of proteins, including thylakoid proteins and the large subunit of ribulose biphosphate carboxylase, associated with the structure and function of the chloroplast (1-2). In addition, many components of the chloroplast translational machinery, such as all of the RNAs and some of the ribosomal proteins, are coded by the chloroplast DNA. Although there have been numerous investigations into the genetics of algal chloroplasts, similar studies with higher plants have been hampered by the uniparental (maternal) pattern of transmission of chloroplasts observed in most species, and the shortage of suitable genetic markers (3,4).

Selection of antimetabolite resistant mutants.

Mutants resistant to chemicals that inhibit growth (antimetabolites) are the most readily selected in plant cell cultures. A number of such mutants have been isolated, with resistance to amino acids and their analogs, base analogs, toxins from pathogenic microorganisms, herbicides, salts, and antibiotics. The mutants can be used for fundamental investigations into cellular metabolism, as markers for plant genetic manipulation, and in efforts to improve crop tolerance to diseases and agrochemicals.

Grafting in vitro.

Graft formation in plants involves the severing of the vascular system with consequent loss of water and solute transport throughout the plant. This transport must be restored to prevent death resulting from nutrient starvation or dessication.

Biochemical characterisation studies on a leukocyte alloantigen expressed with high frequency in leukaemia patients.

In this report we describe, using a previously characterised monoclonal antibody (NC-2), the biochemical characteristics of a human leukaemia-associated alloantigen. Two proteins with molecular weights of 50 kDa and 15 kDa were immunoprecipitated from 125I surface labelled HL-60 cells. Both proteins appeared to be sensitive to digestion with trypsin, the 50 kDa protein in particular.

Identification of a leukocyte alloantigen with a high-frequency expression in leukemia patients.

In this report we describe the production and characterization of a monoclonal antibody to the human promyelocytic leukemia cell line HL-60. The antibody, NC-2, is of the IgG1 subclass and precipitates a 50-Kd protein from 125I-labeled HL-60 cells. The antigen is insensitive to treatment with trypsin, papain, or neuraminidase.

The degranulation response in differentiated HL-60 cells.

HL-60 cells differentiate into mature granulocytes in response to treatment with a variety of chemical agents. Such HL-60 cell derived granulocytes display many of the properties associated with their peripheral blood counterpart. In this study we have investigated the development of the degranulation response in dimethylsulfoxide (DMSO) or retinoic acid differentiated HL-60 cells over a six day period.

An investigation of the in vitro inhibition of acetylcholinesterase by the carbamate inhibitor eserine sulphate in eserine resistant strains of Drosophila melanogaster.

1. The kinetics of inhibition of AChE by the carbamate inhibitor eserine sulphate were investigated in five resistant strains of Drosophila melanogaster. 2.

Premature mortality in the Republic of Ireland.

Regional variations in the incidence of premature deaths between 1971 and 1981 arc examined by mapping standardised mortality ratios for deaths under the age of 65. Premature mortality is also examined with regards to the number of years of normal life lost by those who die prematurely, using a specially defined unfulfilled life index. Unfulfilled life and premature deaths arc found to have a higher incidence in the major urban areas and a lower incidence in western counties, although there are some interesting differences in their spatial distributions.

Adolescent conceptions of the homeland: A cross-cultural study.

Irish (135) and United States (123) subjects, aged from 8 to 17 years, wrote essays on their respective homelands. A content analysis revealed that American subjects, as they grow older, identify the homeland increasingly with its political ideals, while Irish subjects identify theirs with certain psychological ideals which they associate with the rural culture and landscape. Irish essays tended to be longer and more varied, and they showed a higher level of affective development.