Low degree of ubiquitination of histone 2A in the dipteran Chironomus tentans

A polyclonal antibody to ubiquitin has been prepared and shown to react with both ubiquitin and ubiquitinated histone 2A (uH2A). Applying this antibody in Western blotting experiments, we have observed that the salivary glands of Chironomus tentans contain an unusually low amount of uH2A (1% of histone 2A), while the amount of free ubiquitin is as abundant as in other animal cells, e.g. HeLa cells. The same low content of uH2A was also found in diploid epidermal cells of Chironomus origin suggesting that the low amount is not a characteristic of the polytene state of chromatin in salivary gland cells but rather a property of C. tentans as a species. The significance of the low degree of ubiquitination is discussed in relation to the information available on the organization of Chironomus chromatin into unusually large chromomeric entities.     

Differences in chemical composition of plants grown at constant relative growth rates with stable mineral nutrition

Summary Leaf chemistry of a willow clone (Salix aquatica Smith) differed significantly when grown at constant relative growth rates depending upon the relative availability of nutrients and light. Concentration of amino acids and nitrate were high in plants grown with a relative surplus of nutrients. Concentrations of starch, tannin, and lignin, on the other hand, were high in plants grown with a relative surplus of carbon. Photosynthetic rates, expressed per unit leaf area, were similar when plants were grown under high light conditions, regardless of nutrient availability. Dark respiration was much higher in plants supplied with abundant nutrients than in those with a more limited supply, reflecting differences in nitrogen concentration of the tissue. The experimental approach allows plants to be grown to a standard size with differing, but highly uniform chemistry. Plants grown in such a manner may provide good experimental material to evaluate interactions between herbivores or pathogens and their hosts.     

Morphological studies on endocytosis of chondroitin sulphate proteoglycan by rat liver endothelial cells

Summary Endocytosis via the hyaluronic acid/chondroitin sulphate receptor of rat liver endothelial cells was studied ultrastructurally, by use of a probe consisting of chondroitin sulphate proteoglycan attached to 15-nm gold particles. The probe bound to the surface of the cells exclusively in coated regions of the plasma membrane. Internalization at 37° C took place in less than one minute during which time interval the bound probe was transferred to coated vesicles. Further transfer to lysosomes was delayed in association with an accumulation of probes in a prelysosomal compartment consisting of large vacuoles in which probes lined the inner aspect of the membrane. Transport to lysosomes occurred only after a lag phase of at least 40–60 min at 37° C.Abbreviations CS chondroitin sulphate - CSPG chondroitin sulphate proteoglycan - CSPG-Au CSPG-gold complex - EM electronmicroscopical or electron microscopy - HA hyaluronic acid - KC Kuppfer cells - LEC liver endothelial cells - PC parenchymal cells - RES reticuloendothelial system     

Wound-induced proteinase inhibitors from tomato leaves. I. The cDNA-deduced primary structure of pre-inhibitor I and its post-translational processing

A cDNA containing the coding region for the complete amino acid sequence of wound-induced proteinase Inhibitor I from tomato leaves was constructed in the plasmid pUC9 and characterized. The open reading frame codes for a protein of 111 amino acids. This deduced amino acid sequence revealed the presence of a 42-amino acid N-terminal sequence that is not found in the native protein. This sequence appears to contain a 23-amino acid segment typical of a signal sequence followed by a 19-amino acid sequence containing 9 charged amino acids. The 42-amino acid sequence is apparently lost during maturation to the native Inhibitor I and represents 38% of the translated protein. The Inhibitor I amino acid sequence contains 71% identity with potato tuber Inhibitor I sequence and 35% identity with an inhibitor from the leech.     

Wound-induced proteinase inhibitors from tomato leaves. II. The cDNA-deduced primary structure of pre-inhibitor II

A cDNA containing the complete amino acid-coding region of wound-induced tomato Inhibitor II was constructed in the plasmid pUC9. The open reading frame codes for 148 amino acids including a 25-amino acid signal sequence preceding the N-terminal lysine of the mature Inhibitor II. The Inhibitor II sequence exhibits two domains, one domain having a trypsin inhibitory site and the other a chymotrypsin inhibitory site, apparently evolved from a smaller gene by a process of gene duplication and elongation. The amino acid sequence of tomato leaf Inhibitor II exhibits homology with two small proteinase inhibitors isolated from potato tuber and an inhibitor from eggplant. The small potato tuber inhibitors are homologous with 33 amino acids of the N-terminal domain and 19 amino acids from the C-terminal domain. Two identical nucleotide sequences of Inhibitor II cDNA in the 3' noncoding region were present that were also found in an Inhibitor I cDNA. These include an atypical polyadenylation signal, AATAAG, and a 10-base palindromic sequence, CATTATAATG, for which no function is yet known.     

Electron microscopic observations on iron-labelled secondary lysosomes in renal tubules in mice

Summary Labelling of renal tubule cytosomes with electron dense iron granules can be attained by daily intramuscular injections to mice of an iron sorbitol citric-acid compound in a total of approximately 50 mg Fe⁺⁺⁺/100 g of body weight. The labelled cytosomes correspond to secondary lysosomes and represent heterolysosomes or ambilysosomes. The evidence suggests that tubule and lysosome function are undisturbed by the labelling procedure. The use of this method for fine structural studies of the interaction between secondary lysosomes and other cytoplasmic organelles and elements is indicated.Microbodies do not incorporate administered Fe⁺⁺⁺. The morphological observations support the opinion that these bodies are formed in specialized portions of the smooth surfaced endoplasmic reticulum of proximal tubule cells.Supported in part by grants from the Swedish Medical Research Council (Projects No. K 67-12x-1006-2, B 67-12x-1006-02K, K 68-12x-1006-03, and B 69-12x-1006-04A). The assistance of Miss Silwa Mengarelli and Miss Britt-Marie Pettersson is gratefully acknowledged.     

Endocytosis in the ureteric duct epithelium of the hagfish (Myxine glutinosa L.)

Summary Solutions containing ferritin or thorotrast particles were microperfused through the ureteric duct of the hagfish. The markers were taken up by the epithelial cells by way of endocytosis and were transported in bulk in apical vesicles. Newly formed apical vesicles containing marker showed bristle coating on the cytoplasmic side of their limiting membrane. This coating appeared to be lost during the movement of vesicles deeper into the cytoplasm.The findings indicate that the epithelial cells in the ureteric duct have capablity for extensive bulk uptake of macromolecules from the luminal fluid. The mechanisms involved in absorption appear to be similar to those in proximal convoluted tubules of mammals.The apical dense tubules observed with some fixation techniques appear to represent collapsed endocytotic vesicles.The authors are indebted to Finn Walwig, Cand. real., Marine Biology Station, University of Oslo, Dröbak, Norway for kindly supplying the hagfishes used in this study. The technical assistance of Miss Signe Fjeldsenden and Miss Britt-Marie Pettersson is gratefully acknowledged.This work has been supported by grants from the Karolinska Institutet Medical School, Stockholm, Sweden (Therese och Johan Anderssons Minne).     

Fine structure of ureteric duct epithelium in the North Atlantic hagfish (Myxine glutinosa L.)

Summary The epithelial cells lining the ureteric duct in the cyclostome, Myxine glutinosa, have a brush border and show specializations of their apical cytoplasm similar to those observed in absorptive proximal tubule cells in higher vertebrate species. These features and the presence of large and numerous cytosomes, presumed to contain lysosomal enzymes, indicate that the ureteric epithelium has taken over some of the functions of the proximal tubule in the atubular kidney of Myxine. Sparsity of basal cytoplasmic processes and mitochondria in the ureteric duct cells appears to correlate with an inability for active, energy-dependent secretory and ion transport functions.This study has been supported by a grant from the Karolinska Institutet Medical School, Stockholm, Sweden (Therese och Johan Anderssons Minne). The author is indebted to Doctor Bertil Swedmark for permission to use the facilities of Kristineberg Marine Biology Station, Fiskebäckskil, Sweden, where hagfish were caught.     

Production of TNF-alpha and TNF-beta by staphylococcal enterotoxin A activated human T cells

Staphylococcal enterotoxin at concentrations of less than 1 pg/ml induces significant TNF activity in human peripheral blood T cells and monocytes. Maximal TNF activity is routinely detected after 48 to 72 h of culture. IL-2 and IL-4 were both growth promoting for human T cells but only IL-2 could efficiently induce TNF production. The production of TNF-alpha and TNF-beta differed greatly in kinetics. An early intracytoplasmatic production of TNF-alpha after 6 h was detected in both monocytes and T cells whereas a late production of TNF-beta (lymphotoxin) after 48 h, occurred in the T cell population. Induction of TNF-alpha and TNF-beta production by Staphylococcal enterotoxin requires the presence of both monocytes and T cells. The CD4+45R- but not CD4+45R+ and CD8+ cells supported TNF-alpha production in monocytes. The main lytic component from Staphylococcal enterotoxin-activated mononuclear cells is TNF-beta. CD4+ and CD8+ T cells produced about equal amounts of biologically active TNF into the culture supernatants but a fourfold higher frequency of TNF-beta producing cells was demonstrated among CD4+ vs CD8+ cells. The CD4+45R- T cell subset was an efficient producer of TNF-beta and IFN-gamma whereas the CD4+45R+ T cell subset produced significant amounts of TNF-beta but only marginal amounts of IFN-gamma.