Made available in DSpace on 2014-10-09T12:23:07Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:56:18Z (GMT). No. of bitstreams: 1 01282.pdf: 3441497 bytes, checksum: bcede902943026db9c72fb12c44d363d (MD5) / Tese (Doutoramento) / IEA/T / Faculdade de Medicina, Universidade de Sao Paulo - FM/USP

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Growth and immunity are essential physiological functions that are each energetically costly. Thus, energetic allocation into these systems must be appropriately balanced throughout life. Such 'tradeoffs' require molecular-level cross talk between growth and immunity. Limited data suggests that the growth hormone (GH) – insulin-like growth factor (IGF) axis, a key pathway regulating vertebrate growth, also has a role in immune function. Here I exploit salmonid fishes to characterise the regulation of GH-IGF axis genes under multiple experimental contexts where growth and immunity were being traded-off. Specifically, I examined the transcriptional response of the GH-IGF axis to in vivo immune-stimulation at different stages of ontogeny, considering several tissue contexts (i.e. whole fish, immune tissues, and skeletal muscle) and animals with distinct growth rates driven by GH-overexpression. To better contextualise the data, I established the regulation of key gene markers for muscle growth and immune status. Further, I considered gene duplicates retained from whole-genome duplication events in salmonid evolutionary history, exploiting new genomic resources for gene characterisation (e.g. novel IGF-IR paralogues). Four major conclusions arose from my studies. First, up-regulation of IGFBP-1A1 and IGFBP-6A2 (known IGF inhibitors), following disease challenge, suggests that IGF signalling is repressed during infection, promoting energetic reallocation towards immunity. Second, the combined regulation of multiple IGF system genes in immune tissues suggests that while IGF signalling is repressed during infection, IGFBP-6A2 may directly stimulate immune tissues, likely via IGF-independent mechanisms. Third, coregulation of IGFBP-1A1 and IGFBP-6A2 with immune markers indicates direct regulation of the IGF system by conserved cytokine pathways. Finally, an altered skeletal muscle response to immune-stimulation suggests that modulation of GH-IGF axis regulation by GH-overexpression results in compromised fish health. Overall, these findings have broad implications for aquaculture, where fast growth and immunocompetence are traded-off, while improving our basic understanding of fish growth and immunity.

Made available in DSpace on 2014-10-09T12:23:07Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:56:18Z (GMT). No. of bitstreams: 1 01282.pdf: 3441497 bytes, checksum: bcede902943026db9c72fb12c44d363d (MD5) / Tese (Doutoramento) / IEA/T / Faculdade de Medicina, Universidade de Sao Paulo - FM/USP

Made available in DSpace on 2014-10-09T12:24:41Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:05:02Z (GMT). No. of bitstreams: 1 01251.pdf: 1643812 bytes, checksum: 65192b877e878aea892352cedb15f5a6 (MD5) / Tese (Doutoramento) / IEA/T / Instituto de Biociencias, Universidade de Sao Paulo - IB/USP

Made available in DSpace on 2014-10-09T12:23:47Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:51Z (GMT). No. of bitstreams: 1 01287.pdf: 577057 bytes, checksum: 28c9a3861dd9f4082e899a67976d769e (MD5) / Dissertacao (Mestrado) / IEA/D / Faculdade de Medicina Veterinaria e Zootecnia, Universidade de Sao Paulo - FMVZ/USP

No description available.

Surgical removal of presumptive bursal tissue at 72 hr in ovo results in high mortality before hatching and low survival in the first week thereafter. The viable chicks are underweight and usually remain so. Both the spleen and thymus of the bursectomized (Bx) chicks are reduced in size and lymphoid population. The effect on the thymus may be related to stress and subsequent adrenal cortical activity or may reflect some endocrine function of the bursa necessary for the maturation of thymic lymphoid tissue. The effect on the spleen seems to be more direct. In the absence of the primary level organ which induces maturation of the stem cells, the number of germinal centres in the secondary level organ is reduced. Some of the remaining germinal centres may be of T-cell origin, although these cells are more commonly found in diffuse lymphoid areas. The bulk of the germinal centres found in the Bx spleen must be of B-cell origin. Repeated stimulation of the humoral immune system with antigens and mitogens elicits a response in some Bx birds. The response is generally not found in the primary stimulation and is rarely of the magnitude of a normal response even after several stimulations. Antibody production may be limited to IgM type immunoglobulin; further studies are necessary to verify this. Autopsy and histological examination of the tissues of the responsive birds failed to show any evidence of residual bursal tissue. Whether these findings constitute proof of the role of the bursa in the humoral immune response or whether they reflect the broader consequences of bursectomy in the development of the bird requires further study. The inductive capacities of the bursa and the source and autonomous capacity of the stem cells thought to be induced in the bursa should also be investigated. The effects of early hormonal and late surgical bursectomy are similar to those found in this study, where an early embryonic surgical technique was used to avoid the possible complications of these other methods. / Land and Food Systems, Faculty of / Graduate

Ferredoxin (Fd), a fifty-five amino acid electron transport protein of the anaerobe Clostridium pasteurianum, has been chosen as the ideal probe for immunoregulation studies. Its critical feature is that it contains two antigenic determinants satisfying the hypothetical minimum requirement for immunogenicity. It was found that both the antibody (as measured by ELISA) and the lympho-proliferative responses to Fd are linked exclusively to the MHC of mice, mapping to K/I-A. Analysis of the response was undertaken at the determinant level with selective enzyme cleavage products of trypsin and carboxypeptidase A which yield respectively a 52 residue C-determinant peptide (devoid of a functional N-determinant), "C", and a 53 residue N-determinant peptide (devoid of a functional C-determinant peptide), "N",. Through the use of these two molecules ("N" and "C") and a doubly digested molecule, "M", the immune response to Fd was dissected. At first, anti-Fd antibody from high responder, H-2[sup=k], mice was shown to be 10-20% "N" specific with the balance of the response "C" directed, while intermediate responder haplotypes, H-2[sup=b] and H-2[sup=s]. demonstrate equal specificity for the two determinants. H-2 mice were uniformly non-responsive. Fd immune T-cells demonstrated lymphoproliferative capacity mirroring the antibody response of B10.BR (H-2[sup=k]) mice: "C" induced proliferation comparable to that with the native molecule, "N" inducing a much lower response, one matched by the "M" peptide. Next, the "N", "C" and "M" molecules were assessed for their immunogenicity in B10.BR, C57BL/10 (H-2[sup=b])and B10.D2 (H-2[sup=d]) mice. "N" was found to induce limited, if any, antibody production whereas it primes for a very good proliferative response (B10.BR only). "M" induced no antibody response in any strain, and minimal proliferation in B10.BR. "C" induced at least two-fold higher antibody in B10.BR and C57BL/10 as compared to native Fd, and converted the B10.D2 non-responders into responders. "C" induced a weak proliferative response in B10.BR. The data suggest that two determinants exist at the B-cell level, while three determinants account for the T-cell response. / Science, Faculty of / Microbiology and Immunology, Department of / Graduate