An Improved Technique for Sequential R-, Q- and C-Banding of Bone Marrow Chromosomes

A procedure for the sequential staining of metaphase cells to provide R-banding, Q-banding and C-banding of chromosomes is described. The combined techniques allow more precise identification of marker chromosomes and more accurate definition of breakpoints in the consistent chromosome translocations that are associated with certain human malignancies.     

An ultrastructural and cytochemical study of the interaction between latex particles and the haemocytes of the wax moth Galleria mellonella in vitro

Summary The plasmatocytes are the major phagocytic blood-cell type in the haemolymph of the wax-moth, Galleria mellonella. In the present study, these cells were allowed to attach to tissue culture dishes for 1 h, rinsed and then incubated with latex beads for up to 72 h. These cells were then fixed for routine transmission electron microscopy and acid phosphatase cytochemistry. Intracellular latex particles were found in tight, ill-defined phagosomes, which were often clearly associated with the Golgi complexes of the plasmatocytes. Fusion of both primary lysosomes and multivesicular bodies with the phagosomes occasionally occurred and this resulted in the accumulation of an acid phosphatase positive reaction product around the test particles. Subsequent experiments showed that this acid phosphatase activity was mainly associated with the primary lysosomes. The results of the lysosome/latex interactions are compared with those obtained from similar studies on the digestive mechanisms in other phagocytes.We are grateful to Professor E.W. Knight-Jones in whose department this work was carried out and to Mrs. M. Colley for help in insect rearing. This work was supported by grants from the Royal Society and the Science Research Council (B/73/0176. and B/RG/2286.0)     

Changes in the immunoglobulin levels of the mouse gut and serum during conventionalisation and following administration of Salmonella typhimurium.

Increasess in all immunoglobulin classes, except IgM, were observed in the sera of specific pathogen-free (SPF) mice beginning 10 days after their removal from barrier conditions. Concentrations of serum immunoglobulins, comparable with those of conventional mice, were obtained in these animals between 21 and 35 days. Following the removal of germ-free mice from their sterile isolaters, their intestinal IgA levels increased over 35 days to attain levels found in conventional animals. A marked increase in serum immunoglobulin occurred within one day following intravenous administration of live Salmonella typhimurium organisms to SPF animals, and this persisted for longer than 7 weeks (the duration of the study), This rapid elevation in serum immunoglobulin was not elicited by nonbacterial antigens, killed Salmonellae, or viable Vibrio cholerae. Negligible amounts of this immunoglobulin increase could be attributed to specific antibody.     

Influence of postirradiation incubation temperature on recovery of radiation-injured Clostridium botulinum 62A spores.

The number of colonies formed by unirradiated Clostridium botulinum 62A spores was independent of temperature, in the range from 20 to 45 degrees C (in 5 degrees C increments); no colonies developed at 50 degrees C. Spores irradiated at 1.2 or 1.4 Mrads produced more macrocolonies at 40 degrees C than at higher or lower temperatures. Apparently, radiation-injured spores were capable of repair of 40 degrees C than at the other temperatures studied. More than 99% of the radiation (1.2 Mrads) survivors were injured and were unable to form macrocolonies in the presence of 5% NaCl. The germinated radiation-injured spores were also sensitive to dilution, resulting in the loss of viability of 77 to 79% of the radiation survivors. At 30 and 40 degrees C, the irradiated spores did not differ significantly in the extent of germination (greater than 99% at both 30 and 40 degrees C), emergence (64% at 30 degrees C and 67% at 40 degrees C), and the maximum number of emerged cells that started to elongate (69% at 30 degrees C and 79% at 40 degrees C). However, elongation was remarkably more extensive at 40 degrees C than at 30 degrees C. Many elongated cells lysed within 48 h at 30 degrees C, indicating an impaired repair mechanism. If the radiation-injured spores were incubated at 40 degrees C in the recovery (repair) medium for 8 to 10 h, they germinated, emerged, and elongated extensively and were capable of repair. If, after 8 to 10 h at 40 degrees C, these cultures were shifted to 30 degrees C, the recovery at 30 increased by more than eightfold, resulting in similar colony counts at 30 and 40 degrees C. Thus, repair appeared to be associated with outgrowth. Repair did not occur in the presence of chloramphenicol at 40 degrees C, whereas penicillin had no effect, suggesting that the repair involved protein synthesis but did not require multiplication.     

Oxidation of compounds metabolized through folate coenzyme pathways in vitamin B12-deficient rats

The effects of vitamin B₁₂ deficiency in rats and dietary supplementation with vitamin B₁₂ and/or l-methionine plus folate on the oxidation of compounds metabolized through folate coenzyme pathways were investigated. Rats fed a vitamin B₁₂-deficient diet oxidized significantly lower amounts in 60 min of l-histidine, glycine, sarcosine, formate, and l-serine to CO₂ than vitamin B₁₂-supplemented controls. Supplementation of the deficient diet with l-methionine plus folate restored the ability to oxidize the ring-2-carbon of l-histidine, the methyl group of sarcosine, and formate to the same level as that observed in animals receiving vitamin B₁₂. In contrast, oxidation of the 1-carbon of glycine and the 3-carbon of l-serine was not restored to control levels by addition of methionine plus folate to the vitamin B₁₂-deficient diet. Inhibition of the metabolism of the 2-carbon of glycine to CO₂ was partially overcome by additional dietary methionine and folate. Glycine synthase activity in homogenates paralleled the in vivo pattern of oxidation of the 1-carbon of glycine to CO₂, whereas sarcosine dehydrogenase activity appeared to increase 2-fold in vitamin B₁₂ deficiency.     

Improvements in a Non-Proprietary Radiometric Medium to Allow the Detection of Some Pseudomonas Species and Alcaligenes faecalis

The addition of [5-¹⁴C]glutamate and [¹⁴C]formate to a non-proprietary medium containing [¹⁴C]glucose, Trypticase, yeast extract, thiotone, and salts enabled the radiometric detection of the presence of nonfermenters of glucose. It did not interfere with the rapid detection of the presence of aerobic and anaerobic sporeforemers and nonsporeformers.     

Cellular defense reactions of insect hemocytes in vitro: phagocytosis in a new suspension culture system.

In a newly developed short-term culture system the plasmatocytes of Galleria mellonella, Pieris brassicae, Calliphora erythrocephala, and Periplaneta americana are the most active cell types in the phagocytosis of latex, chick erythrocytes, and certain bacteria. The granular cells of G. mellonella and the spherule cells of P. brassicae also phagocytose these test particles to a limited extent. This culture system is described, together with the appearance of ingested particles in preparations of living cells, and in fixed and stained monolayers. In culture, the hemocytes clump together due to cell instability in vitro and to the presence of uningested particles. This clumping reaction may be similar to nodule formation observed in vivo in these insects.     

Ultrastructure of the grasshopper proximal femoral chordotonal organ

Summary Calpasoma dactyloptera, a tentacled form of minute, freshwater coelenterate, has been investigated by light and electron microscopy and time-lapse cinematography. Each tentacle consists of a protrusion from a single ectodermal epithelial cell termed a tentaculocyte. hin tentaculocyte vesicles which represent invaginations of the plasma membrane. A cnidocil protrudes into the external medium. The bottom of each nematocyte is elongated as a stalk which extends to the tentacle base, coursing through tubular membrane lined channels within the tentaculocyte. A network of fibers and microtubules, originating in the cnidocil, extends to the base of the nematocyte stalk.Supported by PHS Research Career Development Award 1-K04-GM42595 and NSF Research Grant GB 29284.     

On doing ‘being ordinary’: women's accounts of BRCA testing and maternal responsibility

Abstract

In recent months, genetic testing for the breast and ovarian cancer genes, BRCA1 and BRCA2, has again hit the headlines in the UK press. Four women, all from families with a strong breast cancer pedigree, have asked the Human Fertility and Embryology Authority for permission to screen their embryos for BRCA1/2 mutations. Although this may be a dramatic example of parental responsibility, other studies have shown that women at risk of BRCA-related cancers frequently cite responsibility to others as an important influence on their testing and treatment decision making. In this paper, I explore the decision-making explanations that women at risk of BRCA-related breast and ovarian cancer provide when accounting for their decision to undergo genetic testing. In doing so, I treat women's accounts critically, and examine how and why the women verbalize their explanations in the manner that they do.