TGF-Beta inhibits the in vitro induction of lymphokine-activated killing activity

Summary Employing serum-free media, human peripheral blood mononuclear cells, and purified recombinant interleukin-2 (IL-2), conditions were observed in which the development of IL-2-driven cytotoxic activity was suppressed. The cytotoxic activity of such IL-2-generated lymphokine activated killing (LAK) was tested against natural killer-resistant cultured tumor cells (Daudi, Raji, and a glioma). LAK generation was inhibited by addition of some normal sera, normal platelets, or some tumor cells. Because recent reports have indicated that transforming growth factor-beta (TGF-beta)-like factors are often secreted by tumors and the acidic alpha granules of platelets and can be present in sera, we tested the effect of purified human TGF-beta on the activation of LAK. Our results indicated that TGF-beta is very suppressive for LAK induction, and can completely prevent both the IL-2-driven proliferation and cytotoxicity at concentrations as low as 5 ng/ml. Titrations of IL-2 and of TGF-beta indicated that the suppression is dose-dependent and can be avoided by employing higher levels of IL-2. It was also found that the suppressive effect of TGF-beta can be overcome by washing suppressed cell populations and further culture in low levels of IL-2. Collectively, these data indicate that TGF-beta can be a potent inhibitor of LAK generation under standard activation conditions, but that this effect is regulated by the relative level of IL-2 and may be overcome and/or reversed in vitro.     

Nucleic acid studies on some heterofermentative lactobacilli: Description of Lactobacillus malefermentans sp.nov. and Lactobacillus parabuchneri sp.nov.

Chemotaxonomic studies were performed on some heterofermentative lactobacilli of uncertain taxonomic position. Two strains from beer and six strains from a variety of habitats were found to be distinct from each other and all other Lactobacillus species examined on the basis of DNA-DNA hybridizations and warrant new species for which the names L. malefermentans and L. parabuchneri , respectively, are proposed.     

Potential role of somatomedin inhibitors in the production of diabetic embryopathies

Mouse conceptuses at the 18-21-somite stage were grown for 2-24 h in vitro in the presence of a serum fraction (Mr = 800-1,080 daltons) possessing somatomedin-inhibitory activity (SI) isolated from diabetic rats. Following an 8-h exposure to the SI, DNA and incorporation of 3H-thymidine were reduced in the embryos while 12 h was required to observe a reduction in total protein and RNA. At the 24-h time point, the neurectoderm was thinner than in controls, and autoradiograms of this region showed a substantial decrease in grain density with 3H-thymidine, but not 3H-leucine or -uridine. Effects of the visceral yolk sac (VYS) preceded those on the embryo. The cytoplasm of the VYS endoderm cells from conceptuses exposed to the SI contained many vacuoles by 4 h, which were larger by 24 h. Total protein was greater than in controls from 4 h onward, although 3H-leucine incorporation, which had increased after 2 h of SI exposure, returned to control levels by 8 h. As seen by SDS-polyacrylamide gel electrophoresis, VYSs from conceptuses exposed to the SI for 4 or 24 h were enriched (compared to control VYSs) in four protein bands also present in the culture medium (primarily rat serum), suggesting that protein degradation and/or transfer of amino acids and peptides to the embryo was inhibited in these VYSs. Such a conclusion was supported by a quantitative decrease in proteins and amino acids in the exocoelomic fluid of conceptuses exposed to the SI for 24 h. The altered processing of proteins may therefore represent a primary cause of the SI-induced embryonic abnormalities.     

Social organization and ecology of proboscis monkeys (Nasalis larvatus) in mixed coastal forest in Sarawak

Data are presented from a 16-month study of proboscis monkeys in an area of mixed coastal forest in Sarawak. The population density, social organization, and feeding and ranging behavior are described in detail. Results are compared with those from other primates in an attempt to understand why females of certain species (including proboscis monkeys) transfer between social groups. The scarcity of available food and reasons for the limited habitat preferences of proboscis monkeys are also discussed.     

Increased totipotency of protoplasts from Brassica oleracea plants previously regenerated in tissue culture

Factors affecting the division of cells derived from leaf and cotyledon protoplasts from Brassica oleracea L. var. italica (Green Comet hybrid broccoli) were examined to optimize conditions for plant regeneration and to determine whether there was a genetic basis for improved regeneration from protoplasts derived from plants previously regenerated from tissue cultures [15]. When leaf protoplasts from different plants grown from hybrid seed were isolated and cultured simultaneously, division efficiencies of 1–95% were obtained. Cells from some plants showed high division efficiencies in consecutive experiments while cells from other plants had consistently low division rates. More plants from hybrid seed gave high division efficiencies when cotyledon protoplasts were used. However, cotyledon or leaf protoplasts from selfed progeny of regenerated plants produced more vigorous calli and more shoots than protoplasts from hybrid seed. These results suggest that there may be a genetic component to the increased totipotency of Brassica oleracea protoplasts.     

Fine structure,mechanism of heart function and haemodynamics in the prosobranch gastropod molluscLittorina littorea (L.)

Summary The heart, main blood vessels, and associated structures ofLittorina littorea were examined by scanning and transmission electron microscopy. The auricle is subdivided into two compartments, one receiving blood from the gill and opening to the nephridial gland vein, the other connecting with the latter anteriorly and the ventricle posteriorly.Video recordings were made of the beating heart in vivo and revealed that the auricle expelled blood not only to the ventricle, but also the nephridial gland vein at systole and provided further evidence of tidal flow of blood in the vein. There is clear indication that the constant volume mechanism of auricular re-filling is not strictly true inLittorina.Blood pressure in the heart and major vessels was measured using a servo-nulling micropressure system. The rate of formation of urine (derived by filtration of blood through the auricular wall) was measured using [⁵¹Cr] EDTA as a blood marker.Basal blood pressure was slightly above ambient (0.7 cm H₂O). Peak systolic pressure in the ventricle (3.8 cm H₂O) was synchronised with a subambient trough in pericardial pressure (–1.0 cm H₂O); these pressure pulses were out of phase with that of the auricle (2.3 cm H₂O) at systole. The observations are consistent in broad terms with a constant volume mechanism, but this does not take into account urine formation or filling of the nephridial gland vein.A filtration pressure of 1.5 cm H₂O has been demonstrated across the auricular wall throughout the cardiac cycle. Colloidal back pressure appears to be negligible. The mean rate of urine formation is 0.26 l g^–1 min^–1.     

Host Status of Five Weed Species and Their Effects on Pratylenchus zeae Infestation of Maize

The host suitability of five of the most common weed species occurring in maize (Zea mays L.) fields in South Africa to Pratylenchus zeae was tested. Based on the number of nematodes per root unit, mealie crotalaria (Crotalaria sphaerocarpa) was a good host; goose grass (Eleusine indica), common pigweed (Amaranthus hybridus), and thorn apple (Datura stramonium) were moderate hosts; and khaki weed (Tagetes minuta) was a poor host. Only the root residues of khaki weed suppressed the P. zeae infestation of subsequently grown maize. When goose grass, khaki weed, and mealie crotalaria were grown in association with maize in soil infested with P. zeae, goose grass and khaki weed severely suppressed maize root development; this resulted in a low number of nematodes per maize root system and a high number of nematodes per maize root unit. Mealie crotalaria did not restrict maize root growth and did not affect nematode densities per maize root system or maize root unit. Special attention should be given to the control of mealie crotalaria, which is a good host for P. zeae, and goose grass, which, in addition to its ability to compete with maize, is also a suitable host for P. zeae.     

Growth factor involvement and oncogene expression in prostatic tumours

The effects of EGF, TGF alpha and 5 alpha-dihydrotestosterone on the growth of a prostatic epithelial cell line have been evaluated in clonal growth assays. Similar bioassay systems have been used to identify tumour-associated growth promoters derived from a human prostatic carcinoma cell line (PC3). Growth factor activity was associated with proteins of Mr 20-30 kDa. In a separate study, EGF receptor concentration and cellular proto-oncogene expression was assessed in prostatic tumour samples. In prostatic carcinoma samples, strong correlation was observed between EGF receptor concentration and c-myc expression. There were no significant correlations between EGF receptor concentration and tumour grade or androgen receptor content in carcinoma samples. EGF receptor concentration was significantly higher in prostatic carcinoma specimens than in BPH.     

Effects on growth and sporulation of inactivation of a Bacillus subtilis gene (ctc) transcribed in vitro by minor vegetative cell RNA polymerases (E-sigma 37, E-sigma 32)

Summary The E-³⁷ gene ctc was inactivated by a site-specific insertion into the Bacillus subtilis chromosome. The resulting mutation inhibited sporulation by 95% at elevated temperatures (48° C). If the ctc ^- mutation is placed in a strain that carries a mutation in the closely linked but distinct spoVC gene, ctc now affects both growth and sporulation at elevated temperatures. Growth of the ctc ^- spoVC285 strain was transiently inhibited when exponentially growing cultures were shifted from 37° C to 48° C. A similar, but less pronounced growth lag, was also seen in a B. subtilis strain carrying only the spoVC-285 mutation. This finding suggests that both the ctc and spoVC products function in vegetatively growing B. subtilis.     

Direct staining and visualization of endothelial monolayers cultured on synthetic polycarbonate filters

Endothelial and epithelial cells cultured on synthetic filter supports have been used to study permeability and transport under various experimental conditions. However, because of the non-transparent nature of these filters, morphological studies using light microscopy are not possible. Presently, investigators circumvent this problem by using cells cultured on glass coverslips, extrapolating morphological data from a system clearly different from that used for functional studies. We describe here a useful technique for direct staining and visualization of cells grown on polycarbonate filter supports, using fluorochrome probes and fluorescence microscopy. We have utilized acridine orange, rhodamine phalloidin, and an anti-vimentin monoclonal antibody to provide information about cell shape, monolayer configuration, and cytoskeletal protein distribution in cultured calf pulmonary artery endothelial cell monolayers. Comparison staining of coverslip and filter preparations revealed a number of clear differences in these parameters. This technique should enable investigators to perform the necessary studies to obtain direct correlations between functional and morphological data.