Lambda Ig constant region genes are translocated to chromosome 8 in Burkitt''s lymphoma with t(8;22)

By in situ hybridization of normal human chromosomes with a cloned genomic probe specific for the constant region of the lambda immunoglobulin genes, band 22q11 was preferentially labelled. In two cell lines with t(8;22) derived from Burkitt's lymphoma a strong signal was noted on the 8q+ chromosome derivative, indicating that the constant region of the lambda Ig gene cluster was translocated from chromosome 22 to chromosome 8. In addition, the signal observed on the 22q- derivative chromosome was stronger than the background in one of the two cell lines tested, but not in the other. The implications are that the break point in chromosome 22 in some cases lies within the Ig gene itself or between clusters of such genes, and that different cases have different break points.     

Amino acid sequence of the N-terminal 139 residues of light chain derived from a homogeneous rabbit antibody

The amino acid sequence of the N-terminal 139 residues of the L (light) chain derived from a homogeneous rabbit antibody (designated BS-1) to type III pneumococci was determined. A combination of methods involving tryptic cleavage restricted to the 2 arginine residues of the molecule and mild acid hydrolysis of a labile peptide bond between the V (variable) and C (constant) regions of the L chain (Fraser et al., 1972) allowed the isolation of two large peptides comprising the entire V region (residues 1-109); these peptides were suitable for automated Edman degradation. The complete sequence analysis of the V region was carried out with only 4mumol of L chain. This material was homogeneous, although minor variant sequences, if present at the 10% value, would not have been detected. The L chain contains 3 intrachain disulphide bridges, whose pairing was established by diagonal electrophoresis: there is one V-region bridge between positions 23 and 88 and one C-region bridge between positions 134 and 194; the third one connects V and C domains between positions 80 and 171. When compared with the basic sequence of human kappa chains, rabbit L chain BS-1 appears to be more similar to the V(KI) prototype sequence than to V(KII) or V(KIII) sequences, where V(KI), V(KII) and V(KIII) represent subgroups I, II and III respectively of V regions of kappa light chains. The V regions of rabbit heavy and light chains are homologous to each other. The presence of two clusters of 3 glycine residues in positions 94-96 and 99-101 respectively is remarkable. Residues 94-96 may be related to antibody complementarity whereas residues 99-101 function probably as a pivot permitting the combining region of the L chain to make optimal contact with the antigenic determinant (Wu & Kabat, 1970).     

Cellular aspects of tolerance. I. Parameters of tolerance induction in T cells of spleen and thymus

Unresponsiveness of T cells in thymus and spleen of tolerant animals was determined by reconstitution of lethally irradiated recipients. The degree of responsiveness of these animals was assessed by antigen elimination and two types of plaque assays (liquid and agar) with different sensitivity. Unresponsiveness occurred more rapidly in T spleen cells than in thymus cells. Unresponsiveness of T cells could be induced in the spleens of thymectomized animals and in T cell repopulated thymectomized lethally irradiated recipients. Induction of unresponsiveness did not depend on proliferating bone marrow cells or on accessory cells.     

Serum-dependent depression of alkaline phosphatase in HeLa cells

Reduction in alkaline phosphatase activity was observed when HeLa S3 cells were grown in Puck's medium containing high concentrations of human serum. This effect was not seen with the enzyme of Chang liver 8A cells. The induction of increased alkaline phosphatase in HeLa S3 by prednisolone or by osmolality changes was not prevented by serum. The concentration of serum in the culture medium had no influence on acid phosphatase activity.     

Formation of prototrophs in mixtures of two auxotrophic mutants of Serratia marcescens HY by a transducing bacteriophage produced by some auxotrophs

Summary Prototrophs arising in mixtures of two auxotrophs of Serratia marcescens strain HY are caused by a filtrable agent produced by one of the partners. 3. donors of this filtrable agent, HY/thyl, HY/ade11, and HY/thr2, were found among 16 auxotrophs, strain HY/thyl producing the agent of the highest activity. The prototrophic wildtype HY is not a donor. The agent does not enhance the growth of the auxotrophic recipient bacteria on minimal medium, therefore the increase in prototophs is not due to more spontaneous mutations. Dilution experiments showed that the reaction of one agent particle with a recipient-cell can cause a prototroph and that the number of recipient cells is not the limiting factor of prototroph formation.When the donor of a filtrable agent contained (besides the agent-inducing thyl-auxotrophy) a second auxotrophy of the same type as the recipient the relative frequency of prototrophs formed was much lower than that one produced by the HY/thyl filtrate. This indicates an influence of pseudoallelism of the markers on prototroph formation as would be expected by transfer of genetic material.The filtrable agent is non-dialyzable, precipitates by ammonium sulfate and is resistant to unspecific phosphodiesterase. When the filtrate was centrifuged in a CsCl density-gradient (24 hours at 35000 rpm) a band occurred at a density of 1.497 g/cm³ which contained the activities for prototroph and plaque formation. It contained also much material with an UV-absorption spectrum typical of phages. Electron micrographs revealed this material to consist of phage particles with hexagonal heads of 50 m diameter and a very short tail. These particles were named y phage.One strain, AX, of Serratia marcescens (among 47 tested) gave small, turbid plaques with filtrates from the known donors but not from other auxotrophs or HY. The plaque titer of y phage on AX was about the same as the transduction to prototrophy of HY/leu27. Phage y is a general-transducing bacteriophage of Serratia marcescens HY since 13 auxotrophic markers of strain HY and 10 of strain AX could be transduced. The low e.o.p. of y phage produced by HY/thyl, may therefore not be due to restriction by the AX cells but may indicate that this y phage is defective.     

Antigenic relationships between Aracoccidioides loboi and other pathogenic fungi determined by immunofluorescence

Summary The fluorescent antibody technique was used to study antigenic relationships betweenParacoccidioides loboi and other pathogenic fungi. The findings suggest thatP. loboi is more closely related antigenically to certainP. brasiliensis strains than to others and that it has antigens in common with the yeast form ofHistoplasma capsulatum, H. duboisii, Blastomyces dermatitidis, Candida albicans and also the mycelial form ofCoccidioides immitis. Serum globulins from 3 cases of keloidal blastomycosis were labelled with fluorescein isothiocyanate. These conjugates showed slight or no reactivity withP. loboi, the yeast forms ofP. brasiliensis, H. capsulatum, H. duboisii andB. dermatitidis, However, they stained brightlyC. albicans, serotypes A and B, the tissue form ofC. immitis and the yeast form ofSporotrichum schenckii. Adsorption of these reagents withC. albicans eliminated all staining except that forS. schenckii. These patients had no history of clinical sporotrichosis.Deceased. Last address: Fundacão Gonçalo Moniz, Salvador, Bahia, Brazil. Requests for reprints should be sent to Dr.William Kaplan.Dr.Miranda is in private practice in Rio de Janeiro, Brazil.