Response of human fetal lymphocytes in xenogeneic mixed leukocyte culture: Phylogenetic and ontogenetic aspects

Cells from liver, thymus, and spleen of human fetuses at different stages of development were capable of a proliferation response against xenogeneic and allogeneic lymphocytes. The kinetics of fetal responses against rat lymphocytes were identical to those of fetal and adult responses against allogeneic cells. With all of the cell types studied, including adult lymphocytes, allogeneic responses were stronger than xenogeneic. Xenogeneic responses against lymphocytes from rat, mouse, or sheep were stronger than those against lymphocytes from rabbit, chicken, snake, or frog. These results are interpreted to indicate that recognition of foreign lymphocytes by human lymphocytes depends on the phylogenetic position of the species used as a source of stimulating cells. The degree of recognition decreases as the phylogenetic distance increases. Specific elimination of responding cells and restimulation with another cell population was used to study the specificity of proliferation responses against mouse and rat lymphocytes. Responses by prethymic liver cells from human fetuses were not due to the existence of specifically recognizing subpopulations. Thymus and spleen at 16 weeks' gestation contained specific subpopulations capable of differentiating between xenogeneic and allogeneic cells, as well as between xenogeneic cells with different intraspecies histocompatibility patterns. Generation of receptor diversity on T lymphocytes is discussed briefly in the light of these findings.     

Drosophila acidic ribosomal protein rpA2: Sequence and characterization

A cDNA encoding the Drosophila melanogaster acidic ribosomal protein rpA2 was cloned and sequenced. rpA2 is homologous to the Artemia salina acidic ribosomal protein eL12′. In situ hybridization to salivary gland polytene chromosomes localizes the rpA2 gene to band 21C. It is a single copy gene, with an mRNA of 0.8 kb. Two-dimensional gel electrophoresis of Drosophila ribosomal proteins followed by immuno-blotting showed that the rpA2 protein has an apparent relative mobility in SDS of 17 kD and an isoelectric point less than pH 5.0. Although the Drosophila gene rp21C may be the same as rpA2, the reported sequences differ. Comparisons of the aligned nucleotide sequences coding for the acidic ribosomal proteins rpA1 and rpA2 of Drosophila with those of other eukaryotes support the view of two separate, though closely related, groups of acidic proteins. Comparison with the Artemia homologues suggests that nucleotide identity may have been conserved by some constraint that acts in addition to the requirement for substantial similarity of amino acid sequences. © 1993 Wiley-Liss, Inc.     

Catecholamine-synthesizing enzymes in the rat stomach

Local production of catecholamines in the stomach of the rat was studied by immunohistochemical demonstration of tyrosine hydroxylase (TH), dopamine--hydroxylase (DBH) and phenylethanolamine-N-methyltransferase (PNMT), the enzymes catalyzing the formation of dopamine, noradrenaline and adrenaline, respectively. A rich innervation of TH- and DBH-immunoreactive nerve fibers was seen in the muscular layers and the myenteric plexus, in the submucosa and in the walls of submucosal blood vessels and in the lamina propria at the base of the epithelial layer. In addition, TH-, but not DBH-immunoreactive nerve fiber networks surrounding ganglion cells in the myenteric plexus were frequently observed, indicating dopaminergic preganglionic innervation of the myenteric plexus. In the oxyntic epithelium, single TH- and DBH-immunoreactive fibers extended in the strands of lamina propria as far as the middle portion of the gastric glands. A small population of single angulate cells in the oxyntic epithelium showed TH-, but not DBH-immunoreactivity. No specific PNMT immunoreactivity was observed.     

Uterine and lung uteroglobins in the rabbit: Two similar proteins with differential hormonal regulation

Previous studies have shown that several rabbit tissues contain proteins which cross-react in the radioimmunoassay for uteroglobin, a progestin-regulated protein in rabbit uterus (Torkkeli et al. (1977) Mol. Cell. Endocrinol. 9, 101–118). In the present study, a uteroglobin-like protein was purified to an apparent homogeneity from an extra-uterine tissue, rabbit lung, by successive chromatographies on hydroxyapatite, Sephadex G-75, SP-Sephadex, DEAE-cellulose and CM-cellulose. The final preparation behaved homogeneously in various polyacrylamide gel electrophoretic systems and in isoelectric focusing. The uteroglobin-like protein isolated from the lung had very similar physico-chemical and immunological properties to those of uteroglobin present in the rabbit uterine fluid. The two proteins had: (i) the same molecular weight, of approx. 13 000, with a two subunit structure (each approx. M_r 7000); (ii) identical behavior in polyacrylamide gel electrophoresis under non-denaturing and denaturing conditions; (iii) the same isoelectric point at pH 5.4; (iv) absence of carbohydrate in the molecule; (v) very similar amino acid compositions; (vi) lack of tryptophan among the amino acids; (vii) the same N-terminal amino acid (glycine), and (viii) indistinguishable immunological characteristics. Collectively, these data strongly suggest that uterine and lung uteroglobins are identical proteins.In contrast to the induction of the uterine uteroglobin by steroids with progestational activity, the synthesis of extra-uterine uteroglobins was not affected by these steroid hormones to any major extent. In keeping with the concept that lung is a target tissue for glucocorticoid action, cortisol and dexamethasone were capable of increasing the concentration of lung uteroglobin 3-fold (from 3 to 9 μg/mg soluble protein). These compounds did not, however, alter the secretion of the uterine protein. Administration of high doses of testosterone and 5α-dihydrotestosterone elevated significantly the content of both uterine and lung uteroglobin. Only approx. one-fifth of the adult pulmonary uteroglobin levels were present in lungs of newborn rabbits indicating that developmental changes occur in the lung uteroglobin content.     

Fibronectin expression is determined by the genotype of the transformed parental cells in heterokaryons between normal and transformed fibroblasts

The expression of fibronectin, a cell surface-associated transformation-sensitive glycoprotein, was studied in hetero- and homokaryons of normal and SV40-transformed human fibroblasts. In immunofluorescence, fibroblast homokaryons had an intense surface-associated and intracelluar fibronectin fluorescence similar to that of normal fibroblasts. Transformed cells and their homokaryons had a minimal surface-associated and a weak intracellular fibronectin fluorescence. In heterokaryons formed between transformed and normal fibroblasts, the expression of fibronectin fell within 24 h to the level of the transformed cell homokaryons. The change was detectable already at 3 h after fusion and was gene-dose dependent. These results show that the transformed genotype determines fibronectin expression in the heterokaryons.     

Root-associated n(2) fixation (acetylene reduction) by enterobacteriaceae and azospirillum strains in cold-climate spodosols

N(2) fixation by bacteria in associative symbiosis with washed roots of 13 Poaceae and 8 other noncultivated plant species in Finland was demonstrated by the acetylene reduction method. The roots most active in C(2)H(2) reduction were those of Agrostis stolonifera, Calamagrostis lanceolata, Elytrigia repens, and Phalaris arundinacea, which produced 538 to 1,510 nmol of C(2)H(4).g (dry weight). h when incubated at pO(2) 0.04 with sucrose (pH 6.5), and 70 to 269 nmol of C(2)H(4). g (dry weight).h without an added energy source and unbuffered. Azospirillum lipferum, Enterobacter agglomerans, Klebsiella pneumoniae, and a Pseudomonas sp. were the acetylene-reducing organisms isolated. The results demonstrate the presence of N(2)-fixing organisms in associative symbiosis with plant roots found in a northern climatic region in acidic soils ranging down to pH 4.0.     

Hormonal control of uteroglobin secretion in rabbit uterus. Inhibition of uteroglobin synthesis and messenger ribonucleic acid accumulation by oestrogen and anti-oestrogen administration

Investigations were conducted to quantify activity of uteroglobin mRNA and secretion of uteroglobin in rabbit uterus after administration of progesterone and 5alpha-dihydrotestosterone, either alone or concomitantly with oestradiol-17beta and tamoxifen, a non-steroidal anti-oestrogen. Poly(A)-containing mRNA was isolated from the uterine tissue by extraction with phenol/chloroform, precipitation with ethanol and chromatography on oligo(dT)-cellulose. Cell-free translation in vitro of the poly(A)-containing mRNA was carried out in a wheat-germ lysate, and the product isolated by specific immuno-precipitation with anti-uteroglobin antiserum purified by affinity chromatography. Radioimmunoassay was utilized to determine uteroglobin content in the uterine flushings and tissue preparations. When given for 5 days, both progesterone (1mg/kg per day) and 5alpha-dihydrotestosterone (25mg/kg per day) elicited a marked induction of uteroglobin secretion, which was accompanied with accumulation of uteroglobin mRNA in the tissue. Concomitant administration of oestradiol-17beta (50mug/kg per day) or tamoxifen (12.5mg/kg per day) significantly decreased both progesterone- and 5alpha-dihydrotestosterone-induced uteroglobin secretion, with a parallel decrease in the uteroglobin-mRNA activity. The decline in the uteroglobin content of the uterine flushes brought about by oestradiol-17beta or tamoxifen administration was not due to inhibition of secretion of this protein by the endometrial cells, since a simultaneous decrease occurred in the tissue uteroglobin content. After a 5-day pretreatment with progesterone (1mg/kg per day), administration of oestradiol-17beta (50mug/kg per day) during the ensuing 4 days greatly accelerated the decay of the uteroglobin content in the uterine fluid.     

Fibroblast surface antigen (SF): Molecular properties,distribution in vitro and in vivo,and altered expression in transformed cells

We have recently described a cell type-specific surface (SF) antigen that is deleted in chick fibroblasts transformed by Rous sarcoma virus. SF antigen is a major surface component and makes up about 0.5% of the total protein on normal cultured fibroblasts. The antigen is shed from normal cells and is present in circulation (serum, plasma), and in vivo, also, in tissue boundary membranes. The molecular equivalents of both cellular and serum SF antigen are distinct, large polypeptides, one of which (SF210, MW 210,000) is glycosylated and, on the cell surface, highly susceptible to proteases and accessible to surface iodination. Immunofluorescence and scanning electron microscopy have indicated that the antigen is located in fibrillar structures of the cell surface, membrane ridges, and processes. Human SF antigen is present in human fibroblasts and in human serum. We have recently shown that human SF antigen is identical to what has been known as the “cold-insoluble globulin” and that it shows affinity toward fibrin and fibrinogen. Our results also indicate that loss of the transformation-sensitive surface proteins is due not to loss of synthesis but to lack of insertion of the protein in the neoplastic cell surface. Both normal and transformed cells produce the SF antigen, but the latter do not retain it in the cell surface. The loss of SF antigen, a major cell surface component, from malignant cells creates an impressive difference between the surface properties of normal and malignant cells. The possible significance of SF antigen to the integrity of the normal membrane and its interaction to surrounding structures is discussed.     

Lakes as nitrous oxide sources in the boreal landscape

Estimates of regional and global freshwater N₂O emissions have remained inaccurate due to scarce data and complexity of the multiple processes driving N₂O fluxes the focus predominantly being on summer time measurements from emission hot spots, agricultural streams. Here, we present four‐season data of N₂O concentrations in the water columns of randomly selected boreal lakes covering a large variation in latitude, lake type, area, depth, water chemistry, and land use cover. Nitrate was the key driver for N₂O dynamics, explaining as much as 78% of the variation of the seasonal mean N₂O concentrations across all lakes. Nitrate concentrations varied among seasons being highest in winter and lowest in summer. Of the surface water samples, 71% were oversaturated with N₂O relative to the atmosphere. Largest oversaturation was measured in winter and lowest in summer stressing the importance to include full year N₂O measurements in annual emission estimates. Including winter data resulted in fourfold annual N₂O emission estimates compared to summer only measurements. Nutrient‐rich calcareous and large humic lakes had the highest annual N₂O emissions. Our emission estimates for Finnish and boreal lakes are 0.6 and 29 Gg N₂O‐N/year, respectively. The global warming potential of N₂O from lakes cannot be neglected in the boreal landscape, being 35% of that of diffusive CH₄ emission in Finnish lakes.