No description available.

No description available.

Convincing molecular evidence for the existence of both cytokines and their receptors in teleost fish is presented. TGF-β is present in <I>O. mykiss</I> encoding a 112 amino acid mature peptide. An integrin binding site (RGD) and a characteristic tetrabasic cleavage site (RKKR) are present, as is the TGF-β superfamily motif. The mature peptide has 9 conserved cysteine residues (8 of which occur in pairs) as well as two additional conserved TGF-β superfamily residues (Pro₃₆ and Gly₄₆). TGF-β exhibits a wide range tissue distribution including head-kidney macrophages, PBL, brain, gill and spleen tissue, and is encoded by a 2.5Kb mRNA. The trout TGF-β gene is spread over 7 exons, with an additional intron in exon 7 when compared to mammalian and avian models. Isolation of a partial sequence also reveals the presence of TGF-β in a cyprinid species. Phylogenetic analysis suggests trout TGF-β to cluster with mammalian TGF-β1 isoforms, and the avian (TGF-β4) and amphibian (TGF-β5) homologs. Neither TNF-α or TNF receptors were detected in <I>O. mykiss</I> at either the cellular or molecular level. The use of degenerate primers in PCR lead to the isolation of a partial sequence for <I>O. mykiss</I> MHC class I. A full length CXC-R gene of 1.6Kb isolated from <I>O. mykiss</I> displays approximately 65% identity to mammalian CXC-R4 receptors, exhibits the seven-transmembrane domain structure of the G-protein coupled receptors and a tissue-specific distribution. Characteristic superfamily motifs and a putative glycosylation site are present in the sequence. Along with the major features of the adaptive immune response such as the major histocompatibility complex (MHC), T-cell receptor (TCR) and immunoglobulin (Ig), cytokines are now shown to be present at the level of teleost fish.

The work presented in this thesis describes the characterisation of the L-carnitine transporter, OpuC, belonging to the binding protein dependent ABC transporter superfamily. The transporter is encoded on a four gene operon, <i>opuCABCD</i>. The physiological study of two <i>opuC</i> mutants have revealed that this operon encodes the principal carnitine transport system in <i>L. monocytogenes</i>, and that the resulting transporter is specific for carnitine and not the related solute betaine. Usually the activity of this transporter is subject to negative regulation during growth in the presence of peptone. An <i>opuCA</i> deletion mutant retained the ability to utilise carnitine as an osmoprotectant at high concentrations (1 mM), and accumulated a cytoplasmic carnitine pool comparable to the wild-type, suggesting that a second low affinity carnitine transport system must exist in <i>L. monocytogenes</i>. Measurement of carnitine uptakes rates in the presence of 100 mM and 1 mM carnitine revealed that the rate of carnitine uptake in the <i>DopuCA </i>mutant was dependent on the carnitine concentration, confirming the low affinity of this unidentified system for carnitine. The stress inducible sigma factor, s^B, is predicted to play a role in regulating the <i>Listerial </i>osmotic stress response. Studies utilising a <i>sigB</i> deletion mutant revealed that s^B is required for the utilisation of carnitine as an osmoprotectant, by regulating the transcription of the <i>opuC</i> operon in response to hyperosmotic stress. Betaine accumulation is reduced in a strain lacking s^B, in particular Na⁺ dependent betaine transport, although transcription of neither betaine transport systems, <i>gbu </i>and <i>beiL</i>, appear affected by the s^B might play a post-transcriptional regulatory role in betaine accumulation.

The research project was concerned, at the general level, with the relationship between general defensiveness and (a) defensive strategies, (b) values and expectancies of a set of socially cherished needs, (c) need hierarchies, and (d) a change in the experimental setting. The study was divided into three parts: Part I concentrated on hypotheses relating to the broader relationships (a), (b), and (c). General defensiveness was measured by the Marlowe and Crowne Social Desirability Scale (MC-SDS). The specific defence strategies were assessed by a kind of role play technique referred to as the critical incidents technique (CIs). The values and expectancies of a set of social needs were measured by rating scales. The needs were those highlighted by Rotter whose Social Learning Theory formed the conceptual frame of the research. Part II dealt with (d) - the effect of a situational change, in the form of an alleged IQ session, on a previously expressed defensive profile. Part III involved further extension and elaboration of the findings obtained earlier. A different measure of defence style, the Life Style Index (LSI), was employed in examining the role of anonymity and defensiveness on the individual's perception of his/her response bias in questionnaires. Several differences were noted between the high and low MC-SDS scorers in the three parts of the study. These differences were explained in terms of (1) the tendency of the high MC-DSD scorers (high defensive Ss) to project a favourable image of themselves, and (2) their differential susceptibility to situational change.

No description available.

No description available.

No description available.

Four groups of rats (10 rats per group), composing an independent subjects design, were exposed to various amounts of escape training (escape contingent upon a fixed-ratio of 3 lever presses) and inescapable shook, prior to being tested on an escape task identical to the one on which they were trained. Interest was focused on the length of time required for, the number of, and the consistency of successful escapes as measures of disruption in responding. The High conditions consisted of 100 escape training trials and 200 seconds of inescapable shock while the Low conditions consisted of 5 escape training trials and 20 seconds of inescapable shock. The four possible combinations of the escape training and inescapable shock composed the four groups. A summary of the results indicated the production of learned helplessness (as measured by the amount of disruption) was not significantly effected by either the amount of escape pretraining or the amount of inescapable shook given the subjects.

A set of stimuli comprises an equivalence class if the three relations of reflexivity, symmetry, and transitivity are present (Sidman & Tailby, 1982). Although behaviorological researchers have suggested that the training and testing sequence may affect equivalence class formation, this has not been studied directly. The purpose of this study was to investigate the efficacy of two different arrangements of training and testing on the formation of classes of equivalent stimuli. Five middle school students were taught eight conditional discriminations with four classes of stimuli, three stimuli per class (A1B1C1, A2B2C2, A3B3C3, and A4B4C4). A fifth class of stimuli, A5B5C5, was used as control stimuli. Experimental stimuli consisted of five chemical elements, with three attributes per element (name, symbol, and atomic number). The formation of three-member equivalence classes was evaluated by testing students for symmetrical and transitive conditional discriminations involved in the training relations. Two phase arrangements were used with each student. Phase Arrangement I (incorporating n-stage testing) was as follows: (a) AM; (b) B1C1; (c) A1B1 and B1C1 mixed together; (d) test (A1C1, C1A1, A5C5, and C5A5); (e) AM; (f) B2C2; (g) A2B2 and B2C2 mixed together; (h) test (A2C2, C2A2, A5C5, and C5A5); (i) AM, B1C1, AM, and B2C2 all mixed together; and (j) test (AlCl, C1A1, A2C2, C2A2, A5C5, and C5A5). Phase Arrangement II was similar, except that test phases (d) and (h) were eliminated. Stimulus classes A3B3C3 and A4B4C4 were arranged analogously to provide a counterbalanced design. One student performed equally well on equivalence tests with both phase arrangements. Two students performed slightly better on equivalence tests with intermediate testing. One student's performance on equivalence tests demonstrated no equivalence class formation with n-stage testing and much more accurate, although varied, responding with intermediate testing. A 5th student who did not meet the pretest requirements for the study was nevertheless allowed to complete the experimental tasks because his test results were unusual. His first test score was far below chance level, but scores improved with subsequent testing. The results suggest that an intermediate testing arrangement may decrease intersubject variability and, for some individuals, may improve equivalence test performance. / Department of Special Education