In vitro induction of lymphocyte responsiveness by a Strongylus vulgaris-derived mitogen

Proliferation in vitro of peripheral blood lymphocytes both from horses infected with Strongylus vulgaris and from helminth-free ponies was observed in the presence of extracts of the fourth and fifth stage larvae and adults of S. vulgaris. In addition, S. vulgaris extracts induced transformation in cultures of peripheral blood lymphocytes from sheep and dogs and in mouse spleen cell cultures. Nylon wool non-adherent, T cell enriched fractions of lymphocytes from both mice and horses were stimulated by the S. vulgaris larval mitogen while no proliferation was observed in cultures containing nylon wool adherent, B cell enriched fractions. Macrophage co-operation appeared not to be necessary for S. vulgaris mitogen-induced transformation of spleen cells. The S. vulgaris mitogen stimulated a subpopulation of mouse spleen cells different from those responsive to PHA, Con A and LPS. These cells might be T helper cells since B cells were stimulated to proliferate in the presence of both T cells and S. vulgaris larval mitogen. In addition, the supernatant of in vitro cultured larvae of S. vulgaris induced slight, but significant transformation of equine peripheral blood lymphocytes. Therefore, it is possible that the S. vulgaris mitogen released by both viable parasites and degenerating larvae might induce T cell dependent production of immunoglobulin in vivo and account for the beta-globulinaemia, of which IgG(T) is a major component, in S vulgaris infected horses.     

Discrimination by male ring-tailed Lemurs (Lemur catta) between the scent marks of male and those of female conspecifics

Olfaction plays an important role in the social communication of all prosimians. (The experiment reported in this paper forms part of an intensive chemobehavioral study of olfaction in Lemur catta (ring-tailed lemur) being carried out in this laboratory.) Five male Lemur cattawere tested on their behavioral responses to paired scent stimuli. Responses measured were (1) total investigation time, (2) arm-marking, (3) ABO/BO rubbing, and (4) flehmen. Males showed a strong discrimination between the scent stimuli,giving higher levels of response to female scent on measures 1, 3, and 4. This response suggests an olfactory-related preference by males for female scent under controlled conditions. This preference may be a consequence of the females’ dominance over males and the brevity of estrus in L. catta,both of which would favor such choice behavior.     

A mathematical model for lambda dv plasmid replication: analysis of copy number mutants

A mathematical model based on the molecular control mechanisms for lambda dv plasmid replication in a single Escherichia coli cell has been applied to simulate replication of mutant lambda dv plasmids. Model simulations of changes in repressor level and copy number resulting from mutations in the promoter-operator PROR region are consistent with experimental data. Calculated effects on lambda dv plasmid copy number of oligomer formation and of alternations in termination efficiency at tR1 also agree with experiment. The model has been employed to simulate the influence of cro mutants and of cro and tR1 double mutants on copy number and stable maintenance of lambda dv plasmid copy number. The genetic structure included in formulation of the replicon model provides a framework for relating changes in specific genetic loci on the plasmid with resulting alterations in host-plasmid system function.     

Identification of lipopolysaccharides and phospholipids of Escherichia coli in polyacrylamide gels.

Polyacrylamide gel electrophoresis of unfractionated lysates of radioactively labeled cells resolves not only proteins and polynucleotides into discrete bands but also cellular lipopolysaccharides and phospholipids. This allows a determination of the intracellular amounts of all of these macromolecules. In addition, this technique is sensitive enough to detect mutational alterations in lipopolysaccharide structure. Polyacrylamide gel electrophoresis is herein shown to be a useful tool for investigations into the structure of lipopolysaccharides and the synthesis of lipopolysaccharides and phospholipids.     

Perturbation analysis of coupled diffusion and reaction with high-order kinetics

Asymptotic solutions for the effectiveness factor and the concentration profile are obtained for mth-order chemical reactions inside a slab catalyst pellet with Robin boundary condition at the pellet's outer surface. Using perturbation analysis in the limit of large reaction order m, the effectiveness factor and the concentration profile are explicitly determined up to O(1/m). Higher-order solutions can be obtained in a systematic way if desired.     

Interaction of H-2Db with mutant histocompatibility gene H (KH-11) in the mouse

The detectable presence of H (KH-11)b, a mutant non-H-2 histocompatibility gene, was previously shown to depend upon the simultaneous presence, in the skin-graft donor, of both the mutant gene and the H-2b haplotype. The experiments reported here demonstrate that H-2Db is the essential element of H-2b for this interaction. Of two H-2Db histocompatibility mutations, H-2bm13 can replace H-2Db in this interaction, but H-2bm14 cannot.     

Identification and genetics of horse lymphocyte alloantigens

Six hundred horses were tested with lymphocytotoxic antisera derived from 550 parous mares and 58 antisera produced by alloimmunization with horse blood cells. Seven equine lymphocyte specificities were identified using correlation analysis of the test data, absorption analysis and lysostripping. These specificities are expressed on lymphocytes and platelets, but not on red blood cells (RBC). Therefore, these specificities do not appear to be products of any of the eight known blood group systems of the horse. The distribution of these specificities in 113 Thoroughbred horses and 57 Arabian horses is presented. Two specificities are subtypic to two other specificities reported here. Family studies indicated that all of these specificities are products of one genetic system. However, it is not clear whether the system consists of one or more loci.     

Carcinogen aflatoxin B1 is located preferentially in internucleosomal deoxyribonucleic acid following exposure in vivo in rainbow trout

The purpose of this work was to investigate the distribution in chromatin of deoxyribonucleic acid (DNA) adducts of aflatoxin B1, following exposure in vivo. Rainbow trout were injected intraperitoneally with radiolabeled aflatoxin B1, a potent procarcinogen known to readily induced hepatocellular carcinomas in these fish. After maximum incorporation, liver nuclei were prepared and digested with micrococcal nuclease. Mono-, di-, and trinucleosomal fractions were purified from several stages of nuclease digestion, and the lengths and specific activities of their DNA were determined. The results indicate that aflatoxin B1 is approximately 5 times as likely on a per nucleotide basis to localize on internucleosomal (linker) DNA as on nucleosomal core DNA in this system.     

Cis-dominant regulatory mutations affecting the expression of GABA permease in Aspergllus nidulans

Summary In Aspergillus nidulans expression of the gabA gene, the probable structural gene for the -amino-n-butyrate (GABA) permease, is controlled by induction, via the intA gene, ammonium repression, mediated by the areA gene, and probably carbon catabolite repression. Regulatory mutations, tightly linked to gabA, were selected by reverting an areA-2 strain on GABA as nitrogen source. These mutations, gabI-1, gabI-2, and gabI-3 result in increased gabA expression and are cis-dominant in their effects on the gabA gene. Mapping data show that the regulatory mutations map on one side of all gabA^- alleles tested.     

Post-translational processing of 7S and 11S components of soybean storage proteins

The synthesis and processing of the major storage proteins in soybean cotyledons was studied both in vivo and in vitro. The and subunits of 7S as well as the 11S proteins are synthesized as higher molecular weight-precursors on membrane-bound polysomes. The initial translation products of the 7S are proteolytically cleaved during translation suggesting the removal of a signal peptide as evidenced by the presence of 2 and 2 peptides immunoreactive with 7S antibody in the in vitro chain completion products of the membrane-bound polysomes. This is followed or accompanied by cotranslational glycosylation, which increases their size equivalent to that of initially-synthesized precursors. In vivo pulse-labelled 7S and products are of slightly higher molecular weights than the immunoprecipitable chain-completion products, indicating further post-translational modifications. A slow post-translational processing during a period of 1.5 to 16 h yields the final 7S and glycoproteins.Acidic and basic subunits of the 11S protein appear to be synthesized from common large molecular weight (60K-59K) precursors. Antibodies to the 11S acidic component recognize both acidic and basic domains in the precursor while those raised against basic subunits appear to be specific for that region only. The processing of the 11S precursor is also very slow and occurs post-translationally. This slow rate of processing, coupled with a temporal difference in the synthesis of 7S and 11S components, suggests a highly coordinated mechanism for synthesis and packaging of these proteins into protein bodies during seed development.