EFFECTS OF HAEMATOCOCCUS PLUVIALIS ASTAXANTHIN ON HEAT-INDUCED OXIDATIVE STRESS AND CELLULAR SIGNAL TRANSDUCTION PATHWAYS IN POULTRY BROILERS

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dc.contributor.advisorDeng, Youping
dc.contributor.authorKuehu, Donna Lee W.
dc.contributor.departmentMolecular Biosciences and Bioengineering
dc.date.accessioned2025-02-20T22:36:12Z
dc.date.issued2024
dc.description.degreePh.D.
dc.embargo.liftdate2026-02-18
dc.identifier.urihttps://hdl.handle.net/10125/110143
dc.subjectMolecular biology
dc.subjectNutrition
dc.subjectBioinformatics
dc.subjectAstaxanthin
dc.subjectCellular Signal Transduction
dc.subjectHaematococcus pluvialis
dc.subjectHeat Induced-Oxidative Stress
dc.subjectPoultry Broilers
dc.titleEFFECTS OF HAEMATOCOCCUS PLUVIALIS ASTAXANTHIN ON HEAT-INDUCED OXIDATIVE STRESS AND CELLULAR SIGNAL TRANSDUCTION PATHWAYS IN POULTRY BROILERS
dc.typeThesis
dcterms.abstractABSTRACTHaematococcus pluvialis is a species of green microalgae that belongs to the phylum Chlorophyta, class Chlorophyceae, and order Chlamydomonadales. In nature, H. pluvialis is generally found in freshwater ponds, lakes, shallow temporary standing water bodies, depressions in rocks and bird baths. H. pluvialis species of microalgae is able to exist in a wide range of environmental conditions of radiation, temperature, and salt concentrations because of its capacity to encyst. H. pluvialis exhibits two main morphological forms, a green vegetative motile form, and a red non-motile aplanospore form. Under favorable conditions, H. pluvialis exists as a biflagellate, green motile cell, and when exposed to stress conditions such as nutrient deprivation or high light intensity, it transitions into the non-motile aplanospore cyst giving the cells their distinctive red color and accumulation of large amounts of astaxanthin. Astaxanthin is derived from the keto-carotenoid family and has a unique molecular structure that includes a series of conjugated double bonds and polar functional groups. This structure enhances its strong antioxidant properties, as it is lipid-soluble and integrates into cellular membranes, playing a vital role in safeguarding cells from oxidative damage. Astaxanthin has diverse applications in the nutraceutical, cosmetic, food, and animal nutrition industries. Biomedical research investigating its effects on oxidative stress, inflammation and cell signaling pathways are studied for its mechanisms of action and potential health benefits. Astaxanthin is used as a feed additive in livestock and poultry to help reduce oxidative stress and improve overall animal health benefits and welfare. The demand for high-quality protein in commercial poultry production of broilers for meat makes astaxanthin an excellent feed additive. The primary objective of this dissertation was to investigate whether a H. pluvialis-derived astaxanthin-rich dietary feed additive as an exogenous source of antioxidants can mitigate heat-induced oxidative stress in poultry broilers. In this present study, we observed the effects in the ceca microbiome, hypothalamus, ileum small intestine, and thymus tissues of broilers by comparing the growth performance and gene expression of cellular signal transduction pathways among three groups: thermal neutral, heat stress and heat stress with astaxanthin. The thermal neutral temperature was 21–22◦C with 50% relative humidity, and the heat stress temperature was 32–35◦C with 42-50% relative humidity. The broilers were reared under thermal neutral conditions and provided a normal starter feed in the first 21 days, then in the last 21 days provided normal finisher feed, and separated further into the two temperature regimes, with the heat stress with astaxanthin group supplemented with 1.33mg/kg of astaxanthin additive. The results showed a significant negative impact of heat stress on growth performance indicators, and more severely the group without astaxanthin additive, but not statistically significant for the ceca microbiota diversity except for the amplicon sequence variants identified. The metagenomic analysis of the ceca microbiome in the terpenoid biosynthesis enzyme pathway resulted in isopentenyl-diphosphate delta-isomerase enzyme marginally significant in the production pathway of astaxanthin. Glutamate-cysteine ligase the rate limiting enzyme in glutathione biosynthesis was significantly higher in the astaxanthin group over the heat stress group, and the reactive oxygen species degradation pathway resulted in superoxide reductase and catalase peroxidase to be significantly higher in the astaxanthin over the heat stress group, while thioredoxin-disulfide reductase was found to be marginally higher in the heat stress group over the thermal neutral group. The hypothalamus experiments resulted in the upregulation of the astaxanthin treated group across the cell signal transduction pathways for thermoregulatory sensing of the TRP ion channels, NF-kB, NFE2L2, PPARa and cytoprotective capacity genes. The ileum small intestine experiments resulted in the astaxanthin treated group upregulated in the cytoprotective gene expression for HSF2, SOD2, GPX3, and TXN, as well as the upregulation of epithelial integrity genes LOX, CLDN1, and MUC2. Ileum histomorphology measurements showed further physiological changes in the villus and crypt which may be adaptive to preserving intestinal function and optimization of nutrient absorption. The thymus experiments resulted in the heat stress group showing significant upregulation in the signal transduction pathways indicating heat-induced oxidative stress and apoptosis, however, expression levels showed no significant differences between the thermal neutral and heat stress with antioxidant groups, suggesting that astaxanthin may mitigate inflammation and oxidative stress damage. In summary, the findings resulting from the studies described herein suggest that H. pluvialis astaxanthin may mitigate heat-induced oxidative stress in broilers, and that further research into dosing concentrations and additive mixtures may further compliment the protective mechanisms of action and potential health benefits.
dcterms.extent180 pages
dcterms.languageen
dcterms.publisherUniversity of Hawai'i at Manoa
dcterms.rightsAll UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
dcterms.typeText
local.identifier.alturihttp://dissertations.umi.com/hawii:12350

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