Triterpenoids and steroids of some Sapotaceae and their chemotaxonomic significance

Extraction of the bark and timber of four Madhuca and five Palaquium species has yielded β-amyrin, β-amyrin acetate, β-amyrin cinnamate,     

Synergistic effect of heat-shock and UV-irradiation on mitosis and protein synthesis in G2-phase plasmodia of Physarum polycephalum Schw--reduction in UV-induced mitotic delay in a preheat-shocked system

The synergistic effect of UV irradiation and heat-shock during the last 3 hr of G2 phase of the cell cycle in the plasmodia of P. polycephalum, in terms of mitotic delay and inhibition of protein synthesis, has been evaluated. The mitotic delay due to both perturbers coordinately increased closer to mitosis. Maximum mitotic delay was obtained in plasmodia heat-shocked after UV irradiation, indicating the presence in this system of either a heat-labile mitogenic substance which is comparatively less susceptible to UV or a substance which is made more susceptible to hyperthermia by UV. A protective role for heat-shock applied before irradiation has been observed in that, radiation-induced mitotic delay is significantly reduced in this combination. There was severe inhibition of translation in all the perturbed classes. Organelle level effects which are independent of major protein synthetic activities or different levels of heat-shock protein production could be the reason for the lack of correlation between percentage inhibition of general protein synthesis and the extent of mitotic delay with respect to the two double-perturbed systems.     

Gross structure and dimensions of the gills in a hill-stream sisorid catfish,Glyptothorax pectinopterus

Gross structure and dimensions of the gills have been examined in a hill-stream sisorid catfish,Glyptothorax pectinopterus, which remains adhered to rocks by means of an adhesive organ developed on the ventral side of the thorax. The fish shows a greater weight-specific gill area and greater length of the gill filaments by comparison with other hill-stream fishes. Adaptation for life in a hill-stream habitat is shown by the presence of additional filaments on the gills and patches of specialised cells on the filament epithelium.     

Isolation and characterization of salinity resistant mutant of a nitrogen-fixing cyanobacterium, Anabaena doliolum

D.V. SINGH. A.K. TRIPATHI AND H.D. KUMAR. 1991. Sodium chloride, up to 20 mmol/l concentration, had a positive effect on acetylene reducing activity and photosynthetic oxygen evolution of a paddy field cyanobacterium, Anabaena doliolum. Beyond 20 mmol/l level of salinity adverse effects appeared. A mutant resistant to 200 mmol/l NaCl was isolated by nitrosoguanidine mutagenesis. The mutant, NaCl-R₂₀₀, showed about 20–25% more nitrogenase activity and photosynthetic oxygen evolution than the parent. Better capacity of nitrogen fixation and photosynthesis possibly could help the mutant in synthesis of osmotic stabilizer to resist the salinity stress.     

Donor-type activated natural killer cells promote marrow engraftment and B cell development during allogeneic bone marrow transplantation.

Purified NK cells were obtained from mice with severe combined immune deficiency and were activated with human IL-2 (hrIL-2) in vitro to determine if, once activated, these cells could be transferred with compatible bone marrow cells (BMC) and promote marrow engraftment in irradiated allogeneic recipients. After culture with hrIL-2, these cells maintained a phenotypic and lytic spectrum consistent with a pure population of activated NK cells. These activated NK cells were then adoptively transferred with the donor BMC and rhIL-2 into lethally irradiated allogeneic hosts. The addition of NK cells with the BMC allowed for more rapid hematopoietic engraftment as determined through short term studies, and greater donor-derived chimerism with accelerated reconstitution of the B cell population as determined with long term analysis. No evidence of graft-vs-host disease was detected in the recipients receiving the activated NK cells with allogeneic T cell replete BMC and hrIL-2. The mechanism by which the transferred NK cells improved BMC engraftment was at least partly through the abrogation of the host effector cell's ability to mediate resistance to the marrow graft. Thus, the administration of donor-type activated NK cells with BMC and hrIL-2 may significantly augment hematopoietic engraftment and immune reconstitution in the clinical setting of allogeneic BMT without giving rise to graft-vs-host disease.     

Extracellular protease from the antarctic yeast Candida humicola.

The psychrotrophic, dimorphic yeast Candida humicola, isolated from Antarctic soil, secretes an acidic protease into the medium. The secretion of this protease by C. humicola was found to be dependent on the composition of the medium. In YPD or yeast nitrogen base medium containing either amino acids or ammonium sulfate as the nitrogen source, the activity of the protease in the medium was low (basal level). However, when yeast nitrogen base medium was depleted of amino acids or ammonium sulfate and supplemented with proteins, the activity of the enzyme increased. The secretion of the enzyme was greater during exponential growth at low temperatures than during growth at higher temperatures. The purified protease had a molecular mass of 36,000 Da and was inhibited by pepstatin, iodoacetamide, and sodium dodecyl sulfate. Despite the prevalent cold temperatures in Antarctica, this extracellular protease of the psychrotrophic yeast C. humicola was active at temperatures ranging from 0 to 45 degrees C, with an optimum activity at 37 degrees C.     

Transformation by Agrobacterium rhizogenes and regeneration of transgenic shoots of the wild soybean Glycine argyrea

Glycine argyrea accession G1420 was evaluated for its response to inoculation with Agrobacterium rhizogenes strains LBA9402 and A4T, carrying wild type Ri plasmids, and by strains R1601 and A4TIII with engineered plasmids. Hypocotyls from young seedlings were the most responsive in producing roots at inoculation sites. Root production was also dependent on bacterial concentration. Excised, cultured roots produced green nodular callus which regenerated shoots on SC2 medium containing 1.1 mg l^–1 6-benzylaminopurine and 0.005 mg l^–1 indole-3-butyric acid. The transformed nature of the roots and of callus regenerating shoots was confirmed by the presence of opines and by dot blot analysis for Ri TL-DNA. Tissues regenerated from roots transformed by A. rhizogenes strains R1601 and A4TIII exhibited NPTII enzyme activity, confirming the stable integration and expression of the chimaeric kanamycin resistance gene in transgenic tissues.Abbreviations BAP 6-benzylaminopurine - IBA indole-3-butyric acid - NPTII neomycin phosphotransferase II - SDS sodium dodecyl sulphate     

The growth hormone binding protein as a paradigm of the erythropoietin superfamily of receptors.

The growth hormone (GH) receptor belongs to a novel receptor family which shares significant amino-acid sequence homology and includes prolactin receptors, erythropoietin receptors and several cytokines' receptors. GH and three other members of this family of receptors have been shown to have circulating soluble forms. The present review summarizes our knowledge on receptor related binding proteins, discusses their possible biological effects and suggests their use in novel assays for their ligands. The GH-binding protein (GH-BP) was the first to have been described and is used as a model for the concept. A series of indirect pieces of evidence suggest that the measurement of circulating GH-BP may enable an evaluation of the GH-receptor. When covalently bound to GH, GH-BP has been shown to slow the clearance of GH. On the other hand GH-BP competes with the GH-receptor for GH binding and, thus, diminishes the biological effect of GH. We suggest a biological role for GH-BP as follows: an increase in the availability of GH results not only in the upregulation of the GH-receptor but also in increased turnover of this receptor, its internalization and recycling. This is followed by a concomitant increase in GH-BP which, in turn, mitigates the effect of GH by competing with the receptor on GH binding. The extracellular domain of the GH-receptor is homologous, to a large extent, with the sequence of several receptors for hormones and cytokines, which have recently been cloned.(ABSTRACT TRUNCATED AT 250 WORDS)