Effects of SV40 transformation on the cytoskeleton and behavioural properties of human keratinocytes

A cloned cell line (SVK14) with apparently unlimited growth potential was isolated from simian virus 40 (SV40)-infected human foreskin keratinocytes which did not appear to pass through any obvious 'crisis' (Girardi et al., J. Cell. Comp. Physiol., 1965, 65, 69-84). Indirect immunofluorescence microscopy showed that the transformed cells have the SV40 large T antigen in their nuclei and stain positively with LE61, a monoclonal antibody that reacts with a tonofilament determinant normally only found in non-keratinizing simple epithelia. SVK14 cells can be grown in the absence of 3T3 feeders and show an impaired ability to differentiate into squames, and this impairment becomes more marked with passage. At later passages the cells acquire the ability to form colonies in agar and to produce a factor with mitogenic activity which stimulates DNA synthesis in quiescent 3T3 cells. Concomitantly, the SVK14 cells become less sensitive to the growth inhibitory effect of human alpha interferons.     

Progressive changes in haematology and tissue water of sexually mature trout, Salmo gairdneri Richardson during the autumn and winter

Rainbow trout of the Kamploops variety were sampled at intervals from October to the end of March. During this period a decline was noted in red cell count, haematocrit, haemoglobin concentration and plasma osmotic concentration. Increases were seen, however, in mean cellular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration and the water content of liver and dorsal muscle. Sexual differences were found in all values with the exception of mean corpuscular haemoglobin concentration and the water content of both tissues. Males always had higher values in those parameters in which sexual differences were noted. All trends, with the exception of male haemoglobin and mean cellular volume and female mean cellular volume and osmotic concentration, were significantly linear.
None of the findings in this study could be correlated with temperature or photoperiod. Neither could the declining plasma osmotic concentration be correlated with the rising mean cellular volume or tissue water content. However, correlations were noted between haemoglobin and haematocrit, red cell count and haematocrit and between osmotic concentration and haematocrit. A negative correlation was seen between mean corpuscular haemoglobin concentration and mean cellular volume.     

Characterization of plasmids from antibiotic-resistant Shigella isolates by agarose gell electrophoresis.

Gel electrophoresis of DNA from 95 clinical isolates of Shigella sonnei and Shigella flexneri resistant to antibiotics revealed a heterogeneous plasmid population. Most of the plasmids were smaller than 6 megadaltons (Mdal). Six S. sonnei isolates with the most common antibiotic resistance pattern were characterized. They had two plasmids in common: one was a self-transmissible Fi+ plasmid of 46 Mdal encoding resistance to streptomycin and sulphafurazole. In addition, several cryptic plasmids ranging in size from 1.0 to 24.5 Mdal were present. Mobilization of the 5.5 Mdal SuSm plasmid and a 1.0 Mdal cryptic plasmid was demonstrated with all six S. sonnei isolates during conjugation. This mobilization was mediated by the 46 Mdal self-transmissible Fi+ R plasmid and also by a 24.5 Mdal Fi- plasmid carrying no known drug resistance determinants.     

The construction and replication properties of hybrid plasmids composed of the r-determinant of R100.1 and the plasmids pCRI or pSC201

Summary We have cloned the entire r-determinant of the antibiotic resistance plasmid R100.1 on the plasmid vectors pCR1 and pSC201. We find that the hybrid plasmids segregate from cultures in which replication of the vector is blocked. This suggests that the r-det is not capable of autonomous replication.     

Fine structure of Merkel cells in lampreys

Summary The structure of Merkel cells occurring in the epidermis of adult and larval stages of Lampetra spp. is described; it is comparable to that reported from the gnathostome classes. The cells bear microvilli, grouped on the distal and proximal aspects, and are associated with sparsely branching and varicose nerve fibres. One branch of the neurite bears a spur-like process which indents the proximal side of the Merkel cell. Most of the specific Merkel granules are situated in the vicinity of this neurite projection; the cell membrane adjacent to the tip of the spur process bears structures resembling presynaptic densities. Occasionally, desmosome-like junctions are found between the neurite and the Merkel cell.The authors thank the Fresh Water Biological Association and the Department of Biological Sciences, University of Bath, for supplying the material, Dr. H. Fox for giving some prepared blocks of Lampetra planeri adults, Mr. B.L. Pirie for technical assistance, and the Science Research Council for support through grant GR/A/3740.6     

Segregation of Tay-Sachs and Sandhoff alleles in a non-Jewish family.

A non-Jewish family is presented in which the genes for Tay-Sachs disease and Sandhoff disease are segregating. Individuals heterozygous for both alleles have low serum and white cell total hexosaminidase levels together with a proportion of heat-labile hexosaminidase A (HEX A) which falls in the normal range. The individuals would not be detected as carriers of Tay-Sachs disease or Sandhoff disease in a population screening program.     

Mesenchyme cells degrade epithelial basal lamina glycosaminoglycan

We investigated whether turnover of basal lamina glycosaminoglycan (GAG), an active process during epithelial morphogenesis, involves the mesenchyme. Fixed, prelabeled, isolated mouse embryo submandibular epithelia were prepared retaining radioactive surface components, as determined by autoradiographic and enzymatic studies, and a basal lamina, as assessed by electron microscopy. Recombination of mouse embryo submandibular mesenchyme with these epithelia stimulates the release of epithelial radioactivity when the labeled precursor is glucosamine or glucose but not when it is amino acid. The release is linear with time during 150 min incubation. Augmented release of epithelial label requires living mesenchyme which must be close proximity with the epithelia. Although heterologous mesenchymes, including lung, trachea, and jaw, stimulate the release of submandibular epithelial label, epithelial tissues do not. The label released by intact submandibular mesenchyme from prelabeled epithelia is in GAG and in two unique fractions: heterogeneous materials of tetrasaccharide or smaller size and N-acetylglucosamine. Enzymatic treatment of the heterogeneous materials revealed the presence of glycosaminoglycan-derived oligosaccharides. These unique products were not obtained by incubating prelabeled epithelia with a mesenchymal cell extract, suggesting that intact mesenchymal cells are required. N-Acetylglucosamine was also released when mesenchyme was recombined with living prelabeled epithelia which contained labeled basal laminar GAG. Our results establish that submandibular epithelial basal lamina GAGs are degraded by submandibular mesenchyme. We propose that one mechanism of epithelial-mesenchymal interaction is the degradation of epithelial basal laminar GAG by mesenchyme.     

Yeast RNA polymerase II subunit RPB9 is essential for growth at temperature extremes

The Saccharomyces cerevisiae RNA polymerase II subunit gene RPB9 was isolated and sequenced. RPB9 is a single copy gene on chromosome VII. The RPB9 sequence predicts a protein of 122 amino acids with a molecular mass of 14,200 Da. The yeast RPB9 subunit is similar in size and sequence to a protein encoded by DNA adjacent to the suppressor of the Hairy Wing gene in Drosophila melanogaster. Deletion of the RPB9 gene produced cells that were heat- and cold-sensitive. The RPB9 subunit, like the previously described RNA polymerase II subunit RPB4, is not essential for synthesis of mRNA, but is required for normal cell growth over a wide temperature range.     

Primary mesenchyme cell migration requires a chondroitin sulfate/dermatan sulfate proteoglycan

Primary mesenchyme cell migration in the sea urchin embryo is inhibited by sulfate deprivation and exposure to exogenous beta-D-xylosides, two treatments known to disrupt proteoglycan synthesis. We show that in the developing sea urchin, exogenous xyloside affects the synthesis by the primary mesenchyme cells of a very large, cell surface chondroitin sulfate/dermatan sulfate proteoglycan. This proteoglycan is present in a partially purified fraction that restores migratory ability to defective cells in vitro. The integrity of this chondroitin sulfate/dermatan sulfate proteoglycan appears essential for primary mesenchyme cell migration since treatment of actively migrating cells with chondroitinase ABC reversibly inhibited their migration in vitro.