Species-specific aggregation factor in sponges. Sialyltransferase associated with aggregation factor

The sialyltransferase (= glycoprotein-sialic acid transferase) was studied in the sponge Geodia cydonium, a mesozoan organism. The experiments were performed both in intact cellular and in isolated enzyme systems. It is shown, that desialylated cells show a lower aggregation potency than the controls. During aggregation enzymic sialylation of desialylated sponge cells occurs in the presence of an aggregation factor, which is associated with a high molecular weight particle. The sialylation process is temperature-dependent and can be inhibited by N-ethylmaleimide. Sialylation occurs predominantly at a distinct cell surface component, the aggregation receptor. The sialyltransferase was isolated and purified by the following steps: Sepharose 4B, CM-cellulose, Nonidet treatment, and Sephadex G-100. By this procedure the enzyme was purified 680-fold with a 31% yield. The sialyltransferase is originally associated with the high molecular weight particle also carrying the aggregation factor. In the last step the aggregation factor was separated from the sialyltransferase. The enzyme catalyzes the transfer of sialic acid from CMP-sialic acid to the desialylated aggregation receptor. The molecular weight of the sialyltransferase has been determined to be 52,000. Kinetic studies revealed no lag phase and a dependence on enzyme concentration. The purified transferase has a pH optimum of 7.75 and requires 200 mM NaCl for activity. No requirement for Mg2+ or Ca2+ could be observed. The reaction is inhibited by 10 micronM N-ethylmaleimide.

The presence of Herpesvirus Saimiri genomes in virus-transformed cells

Herpesvirus saimiri (H. salmiri) -transformed cells contained both types of viral DNA, unique L-DNA and highly repetetive H-DNA. DNA from spleen and lymph-node autopsies of two tumor-bearing marmoset monkeys contained 0.14-0.75% viral L-DNA -AND 0.115-1.08% H-DNA. This amount of H-DNA would be equivalent to the presence of 14-130 M-genomes per diploid tumor tissue cell. Six virus-transformed lymphoid cell lines, two of them virus-producing, contained 0.69-2.27% H-DNA and more than 0.72-1.95% L-DNA. These concentrations of H-DNA sequences correspond to 83-274 M-genome copies per lymphoid tissue culture cell. The majority of viral genomes in transformed non-producer lymphoid cell lines appeared to be defective, since part of the L-sequences present in virions were found to be deleted in the genome copies of transformed cells. There was a relative excess of repetitive H-sequences in all transformed cells in regard to the ratio of H-DNA/L-DNA in M-genomes of H. saimiri virions.

["Clumping factor"-reactions using staphylococci after their extraction with guanidiniumchloride (author's transl)]

Staphylococci of strain K 807 (ATCC: 31243) have much "clumping factor" (CF) on their surface. Extraction of the staphylococci with 6 M guanidinium chloride, removed all soluble substances, including coagulase, without reduction in CF-activity. The extracted staphylococci proved to be most suitable for the quantitative determination of fibrinogen and fibrin degradation products in a microtiter procedure (fig. 2). The CF-test with staphylococci of strain K 807 was more sensitive compared with the hitherto used strain Newman D2C (table 1). After staining with "Astrazonrot (BBL)" no loss of CF occurred. With the stained staphylococci the CF-reactions became more distinctly visible and gave sharp endpoints.

Species-specific aggregation factor in sponges. VI. Aggregation receptor from the cell surface

An aggregation receptor from the siliceous sponge Geodia cydonium has been isolated and purified in an almost pure form. It sediments at about 2–6s, has a buoyant density of 1–51 g/ml in CsCl and elutes from Sephadex G-50 at a Ve/V0 value of 1–311. Chemical analysis revealed that the receptor consists of 81% neutral carbohydrate and 7-5% protein. The activity of the receptor is rapidly destroyed by Na-periodate. The receptor is released from the cell surface after removal of Ca2+ from the medium or after incubation of the cells with trypsin. The depleted cells can be charged again with isolated receptor molecules. The binding of the receptor molecules on the cell surface is prevented in the presence of trypsin. For optimal binding, physiological salt concentrations with respect to NaCl (540 mM NaCl) and Ca2+ ions are necessary. The receptor whose isolation is described in this report, is involved in secondary aggregation processes, which are initiated by a soluble aggregation factor. The primary aggregation of the cells is not influenced by the receptor. Time-course studies with receptor-depleted cells revealed that new aggregation receptor molecules are formed during the aggregation process. By competition experiments it could be shown that high concentrations of soluble aggregation receptor molecules inhibit secondary aggregation. The soluble receptor molecules can complete with surface-bound receptor molecules only if these are not linked with the aggregation factor.

Anti-actomyosin. Influence on adhesive behaviour of eukaryotic cells and of Cuvierian tubules

The effect of antisera against chicken gizzard smooth-muscle actomyosin and against pectoralis striated-muscle actomyosin on adhesive behaviour of eukaryotic cells (from sea urchin embryos and from a silicious sponge) and of Cuvierian tubules has been studied. The results with sea urchin cells, which require divalent cations for aggregation, showed that antiserum to chicken gizzard smooth-muscle actomyosin inhibited reaggreagation of trypsin-treated cells better than mechanically dissociated cells, while anti-chicken pectoralis striated-muscle had no effect. Primary reaggreagation of trypsin-dissociated sponge cells, in the presence of calcium and magnesium, is also inhibitable by anti-gizzard smooth-muscle but not by anti-pectoralis straited muscle. Anti-gizzard smooth-muscle had no effect on secondary reaggregation of sponge cells mediated by a soluble aggregation factor. Anti-gizzard smooth-muscle inhibited Cuvierian tubule adhesion.

Species-specific aggregation factor in sponges. V. Influence on programmed syntheses

Isolated cells from the siliceous sponge Geodia cydonium as well as small primary aggregates (diameter: 70 mum) consisting of them show no increase in rates of programmed syntheses and mitotic activity with time. After addition of a highly purified aggregation factor to a culture with primary aggregates which subsequently form secondary aggregates (diameter: larger than 1000 mum), a dramatic increase of DNA, RNA and protein synthesis occurs. Together with this increase, the cells show a high mitotic activity. The values for the mitotic coefficient reach a first maximum 8 h after the beginning of the secondary aggregation process. The stimulation of the mitotic activity of cells during the aggregation factor induced secondary aggregation process can be suppressed by inhibitors of RNA and protein synthesis as well as by a blocker of DNA synthesis. This finding may indicate that cells from the G0-population enter the proliferating cell pool via the G1-phase.

[Individual therapy as a special form of complex psychotherapy]

A combination of several psychotherapeutic methods will be meaningfull only if they are tuned to, and supplement, each other. Indiscriminate combinations may produce harmful effects. The choice of psychotherapeutic methods depends upon the objective that the psychotherapist desires to accomplish. In psychotherapy it is essential that all actions taken be governed by plans worked out in accordance with the particular objectives to be accomplished.

Protein synthesis of the sponge Geodia cydonium: characterization of the system

The ribosomal population of the sponge Geodia cydonium has been examined. The monosomes have a sedimentation constant of 80 S, the sizes of the subunits are approximately 60 S and 45 S respectively. The polyribosomes contain up to 40 ribosomal units. Cell free protein synthesizing systems (cell homogenate as well as reconstituted system) have been prepared and characterized with respect to Mg(2+), KCI and ATP concentrations, temperature, pH and time course of the reaction. In the cell-free system and in the cellular system the protein biosynthesis is inhibited by chloramphenicol. It is not affected by cycloheximide.