New protein genetic studies in six Amazonian Indian populations

A total of 732 individuals affiliated with six Amazonian Indian populations were variously studied in relation to 26 protein genetic systems. Eleven of them were found to be monomorphic in these groups, in accordance with previous investigations. Similarities and dissimilarities (the latter involving the Rh, Duffy, haptoglobin and transferrin systems) were observed in relation to earlier investigations in four of these populations (Galibi, Palikour, Mundurucu and Tenharim). A dimeric, cathodal variant of albumin was found among two Galibi subjects, and the fairly common occurrence of CP* ACAY among some South American Indian populations was confirmed. The results in the six populations were compared with those from 29 others. When relationships are searched for among tribes of the same linguistic group, the factor that seems to be most influential is geographical localization, an exception being the pattern observed among the Cayapo subgroups. The latter shows genetic differences of the same level of magnitude as those observed among Ge-speaking tribes.     

Cleavage motifs of the yeast 20S proteasome beta subunits deduced from digests of enolase 1

The 436-amino acid protein enolase 1 from yeast was degraded in vitro by purified wild-type and mutant yeast 20S proteasome particles. Analysis of the cleavage products at different times revealed a processive degradation mechanism and a length distribution of fragments ranging from 3 to 25 amino acids with an average length of 7 to 8 amino acids. Surprisingly, the average fragment length was very similar between wild-type and mutant 20S proteasomes with reduced numbers of active sites. This implies that the fragment length is not influenced by the distance between the active sites, as previously postulated. A detailed analysis of the cleavages also allowed the identification of certain amino acid characteristics in positions flanking the cleavage site that guide the selection of the P1 residues by the three active beta subunits. Because yeast and mammalian proteasomes are highly homologous, similar cleavage motifs might be used by mammalian proteasomes. Therefore, our data provide a basis for predicting proteasomal degradation products from which peptides are sampled by major histocompatibility complex class I molecules for presentation to cytotoxic T cells.     

The beta-gal interferon assay: a new, precise and sensitive method

Cells of a human glioblastoma line were stably transfected with a glial fibrillary acidic protein (GFAP) promoter sequence/lacZ reporter gene. Following this modification, they produced Escherichia coli beta-galactosidase constitutively in amounts that could be measured through their conversion of an added fluorophore into a product readily estimated by fluorimetry. Human interferons (IFN) selectively and in a dose-dependent manner reduce the formation of beta-galactosidase in this system. We have used it as the basis for a novel assay that is sensitive (4-40 pg/ml), precise, completed in 30 h, and applicable to both type I and type II human IFNs. Statistical analysis showed interassay relative standard deviations ranging from 5% to 11%, and most individual assays revealed potencies with limits of error within 85%-115%. Neither partially trypsin-digested IFN nor the other cytokines and mitogens we tested reacted in this system, except for tumor necrosis factor-alpha (TNF-alpha). The high selectivity was further shown by the loss of response to IFN in the presence of the appropriate specific anti-IFN or anti-IFN-gamma receptor antibodies.     

Testicular plasmacytoma following chemical orchiectomy: potential role of hypogonadism in myeloma proliferation

We present a case of a 55 year old man with multiple myeloma who underwent autologous stem cell transplantation and subsequently developed testicular myeloma. Testicular enlargement was observed only after treatment of an incidental prostatic adenocarcinoma with chemical orchidectomy at a time when myeloma was controlled systemically. A subsequent bilateral surgical orchiectomy revealed plasmacytoma in both testis. Enhanced production of B-lymphocytes after castration has been reported and implicates testosterone as a possible negative regulator of B-cell production. We propose that the androgen deficient state may have contributed to the development of plasmacytoma of the testes in our patient. The regulatory role of sex steroids in B-cell development is discussed.     

Optimisation of different physical parameters for bioleaching of phosphate by Aspergillus niger from Indian rock phosphate

A mutant strain of Aspergillus niger AB100 was incubated with samples of rock phosphate. Mutation resulted in a greater amount of solubilisation (30 to 35%) as against the parent strain (10 to 15%). The influence of leaching parameters such as ore concentration (pulp density), particle size, initial pH of the medium, temperature, volume of the medium in 250 ml flasks, inoculum concentration and age of inoculum was studied. When low quantity of rock phosphate is applied (0.1%) the solubilisation of phosphorus was optimal (40.5%). Optimum particle size was--200 to 240 mesh, initial pH of the medium 4.0, optimum volume of the fermentation medium 160 ml, time period of incubation was 8 days, inoculum volume was 7.5 ml, and age of inoculum 7 days. The maximum leaching of phosphorus by using these optimum physical parameters is 45 to 50%.