Resonance Raman spectroscopy can be used to estimate the hemoglobin oxygen saturation. Previous studies have demonstrated that exposure of oxygenated red blood cells to laser illumination may result in photo-induced displacement of oxygen from hemoglobin. In this study, an in vitro model was used to evaluate the relationship between this photo-induced effect and the red blood cell velocity. A computer-controlled system was implemented to acquire variables such as red cell velocity, microvessel diameter and hemoglobin oxygen saturation at multiple sites in selected microvascular networks. Using this system, resonance Raman spectroscopy was employed to measure hemoglobin oxygen saturation gradients in arterioles and venules of the rat mesentery in vivo. In several in vitro experimental conditions, there was a significant decrease in photodamage as red cell velocity increased. As blood flowed downstream in arterioles and venules, increased red blood cell velocity was associated with smaller hemoglobin oxygen saturation gradients in vivo.

Chronic exposure to solar UVA plays a causative role in skin photoaging and photocarcinogenesis. Guided by exploratory difference-in-gel-electrophoresis (DIGE)-proteomics, we identified the thiol-dependent cysteine-proteases cathepsin B and cathepsin L as novel UVA-targets undergoing photo-oxidative inactivation upstream of autophagic-lysosomal dysfunction. In human skin fibroblasts, exposure to noncytotoxic doses of chronic UVA (9.9 J/cm ², twice a week, 3 weeks) caused pronounced photooxidative impairment of cathepsin B and L enzymatic activity suppressed by antioxidant intervention. Western blot analysis revealed extensive 4-hydroxy-2-trans-nonenal (4-HNE) modification of cathepsin B in UVA-exposed fibroblasts. Consistent with lysosomal impairment, accumulation of cellular autofluorescent material colocalizing with lysosomes was observed by confocal fluorescence microscopy, and extensive deposition of lipofuscin was detectable by transmission electron microscopy (TEM). Lysosomal expansion was further evidenced by increased immunodetection of lysosomal associated membrane protein-1 (Lamp-1) and Lysotracker-based flow cytometric analysis. While lysosomal membrane integrity remained intact, autophagic blockade was suggested by accumulation of cellular protein levels of LC3-II and p62 (sequestosome 1) in UVA-exposed fibroblasts. Furthermore, UVA-exposure modulated transcriptional levels of p62 (sequestosome 1, SQSTM1), α-synuclein (SNCA), and transglutaminase-2 (TGM2). Strikingly, pharmacological cathepsin B/L inhibition using CA074Me mimicked UVA-induced accumulation of lipofuscin and autophagic-lysosomal proteins (Lamp-1, LC3-II, and p62), as well as changes at the transcriptional levels. In order to determine if UVA-induced lysosomal impairment requires single or dual inactivation of cathepsin B and/or L, we used a genetic approach (siRNA) to selectively downregulate enzymatic activity of these target cathepsins. Monitoring protein levels of Lamp-1, LC3-II, and p62, we observed that only dual genetic antagonism (targeting both CTSB and CTSL expression) could mimic UVA-induced autophagic-lysosomal alterations, whereas single knockdown (targeting CTSB or CTSL only) did not reproduce the UVA-induced phenotype. Similarly, TEM revealed massive accumulation of lipofuscin-containing lysosomal vesicles in fibroblasts only after CTSB/CTSL-double knockdown. Taken together, our data indicate for the first time that UVA impairs lysosomal function causing autophagic-lysosomal alterations downstream of cathepsin B/L enzymatic inactivation. This work provides evidence for a heretofore unrecognized 'double-hit' mechanism of UVA skin photodamage where primary photo-oxidative insult occurs simultaneously with impaired clearance of damaged molecules and organelles downstream of dual inactivation of cathepsin B and L.

Photosystem II (PSII) is the primary generator of electrons required for photosynthesis. The reaction center protein of PSII (RCII) is the most susceptible component of the photosynthetic machinery to damage. Photodamage can lead to long-term downregulation of photosynthesis. This occurs because plants are exposed to rapid light fluctuations and high light conditions, leading to the over accumulation of excess energy around PSII. Plants have developed a mechanism to dissipate this excess energy called nonphotochemical quenching (NPQ). In order to quantify the protectiveness of NPQ (pNPQ), a novel methodology was developed and employed. During methodology development, development, it is shown that a variable PSI fluorescence should be taken into account, and how it can be calculated. Application of the procedure assessed the contribution of xanthophylls lutein, violaxanthin, zeaxanthin, and the PsbS protein to pNPQ. Results show that the most important factors governing photoprotection are the PsbS protein and the correct xanthophyll composition in their natural binding sites. The more xanthophyll variation, the greater the photodamage at the end of the pNPQ assessment procedure. PsbS is essential to achieve the maximum pNPQ. PsbS increases the aggregation of LHCII. Arabidopsis with excess PsbS has three-times more aggregated LHCII than wild type levels of PsbS. The phototolerance and pNPQ required for Arabidopsis grown under different conditions and for leaves of different ages was also calculated. Plants grown under low light conditions accumulate disconnect antenna (LHCII), which is inefficient at protecting RCII, despite the high NPQ levels. Investigating plants of different ages, it was found that eight-week old Arabidopsis are the optimum age for pNPQ effectiveness. Younger and older leaves suffer photodamage at lower light intensities and form less pNPQ. This thesis demonstrates the novelty and adaptability of the pNPQ assessment procedure, and offers a sound case for its use in acclimation and photoinhibition experiments.

Ultraviolet A is a major spectral component of solar electromagnetic energy reaching the surface of the earth. Excessive exposure to solar UVA is a known contributor to skin photoaging and photocarcinogenesis, associated with increased incidence rates and a significant health burden imposed by skin cancer worldwide. However, the molecular mechanisms underlying UVA-induced skin photodamage remain largely undefined. UVA radiation has been shown to cause cutaneous oxidative stress and photosensitization reactions involving the light-driven photochemistry of specific skin chromophores upstream of reactive oxygen species formation, recognized as key players in skin photooxidative damage. Consequently, there has been significant interest in the identification of endogenous compounds that facilitate these reactions serving as endogenous photosensitizers. In my graduate research, we assessed the potential of selected endogenous chromophores, pyridoxal and 6-formylindolo[3,2-b]carbazole (FICZ), to elicit UVA-induced photo- and genotoxicity in relevant models of human skin, and further identified the underlying molecular mechanisms involved. We demonstrated for the first time that the B6-vitamer pyridoxal, previously shown to contain the phototoxic 3-hydroxypyridine moiety, is a micromolar sensitizer of UVA-induced genotoxicity in human primary keratinocytes and human epidermal reconstructs, which may be relevant to human skin exposed to high concentrations of B6-vitamers. Additionally, we have demonstrated that FICZ, a tryptophan photoproduct and endogenous high-affinity aryl hydrocarbon receptor (AhR) agonist, as the most potent endogenous UVA- and visible light-activated photosensitizer identified as of today. FICZ potentiates photooxidative stress, an effect that occurs independent of AhR ligand activity. Given the extraordinary photodynamic potency of FICZ, which surpasses that of any known endogenous photosensitizer, including protoporphyrin IX, and its rapid metabolic turnover, we tested the feasibility of using FICZ for the photodynamic elimination of malignant skin cancer cells in vitro and in vivo. Indeed, light photoactivation of FICZ-induced phototoxidative damage and cytotoxicity in a panel of cultured human malignant skin cells, and furthermore suppressed post-UVB tumorigenic progression in high-risk SKH-1 mice. Based on these pilot studies, follow up experiments will further optimize FICZ-based photodynamic interventions targeting human skin malignancies in relevant model systems. In pursuit of minimizing the need for invasive therapeutic methods, exploitation of stress response pathways has become a topic of interest for interventions aimed at the eradication of skin cancer at early or late progressional stages. Therefore, we tested feasibility of harnessing the cellular metal stress response for the elimination of skin cancer cells using the zinc-ionophore and FDA-approved microbicidal agent zinc pyrithione (ZnPT). Indeed, in a panel of cultured malignant skin cancer cells it was observed that ZnPT treatment caused rapid intracellular zinc overload and redox dysregulation, followed by a loss of genomic integrity and induction of caspase-independent cell death. In a murine photocarcinogenesis model, chronic topical ZnPT-administration post-UV caused epidermal zinc-overload and stress response gene expression with pronounced blockade of tumorigenic progression. These data suggest the feasibility of repurposing a topical OTC-drug for zinc-directed photochemoprevention of solar UV-induced nonmelanoma skin cancer. In summary, these studies contribute to our mechanistic understanding of photosensitizer- and zinc-induced stress responses in human skin, and furthermore provide the molecular basis for innovative therapeutic strategies aimed at the elimination of skin cancer cells.

El objetivo principal de esta tesis es contrastar el papel de dichos compuestos 1,3-dicarbonilicos como agentes que dañan el ADN con respecto a su potencial fotoprotector. Primero, 5,6-dihidropirimidinas han sido derivatizadas utilizando el grupo fotolábil t-Bu cetona con el fin de estudiar la generación de radicales en C5 en un medio no acuoso. Después, el estudio por fotólisis de destello láser en ACN de los derivados 1,3-dicarbonilicos diseñados da lugar a la detección de los supuestos radicales 5,6-dihidropirimidin-5-ilo. Su caracterización muestra especies transitorias de vida larga y están centrados a 400-420 nm o 350-400 nm para los derivados 5,6-dihidrouridina o 5,6-dihidrotimidina, respectivamente. Además, la generación de radicales también se ha evidenciado mediante experimentos de fluorescencia en estado estacionario mediante el uso de una sonda profluorescente (AAA-TEMPO) que atrapa el radical. Por lo tanto, la irradiación de los derivados fotolábiles del ácido nucleico en presencia de AAA-TEMPO produce un aumento de la emisión, de acuerdo con la captura del radical C5 por la sonda paramagnética. La formación del aducto se ha confirmado mediante UPLC-HRMS. Los datos experimentales se han corroborado con cálculos teóricos ab initio CASPT2 // CASSCF. Segundo, otro derivado 1,3-dicarbonílico de la pirimidina se ha investigado. De hecho, el daño 5-formiluracilo (ForU) presenta características interesantes como potencial agente fotosensibilizador intrínseco del ADN. Por lo tanto, los estudios espectroscópicos revelan que ForU tiene una absorción en el rango UVA/UVB y también presenta un estado triplete excitado (3ForU *) con un tiempo de vida algunos micros y con una ET suficientemente alta como para fotosensibilizar la formación de los conocidos dímeros de pirimidina de tipo ciclobutano (CPDs) a través de una transferencia de energía triplete-triplete. Este proceso ha sido confirmado por medio de la síntesis de díadas modelo Thy-Thy y Cyt-Cyt, ya que su irradiación en presencia de ForU ha demostrado que producen CPDs. Asimismo, el estudio en ADN plasmídico permitió establecer la capacidad de ForU para inducir roturas de cadena simple y CPDs. A continuación, se ha desarrollo una nueva estrategia para la fotoprotección de moléculas bioactivas aprovechando la reactividad fotoquímica del tautómero 1,3-dicetona de la avobenzona (AB), un filtro del UVA. Los compuestos seleccionados son dos fármacos antiinflamatorios no esteroideos de uso tópico con propiedades fotosensibilizantes, (S)-ketoprofeno (KP) y diclofenaco (DF). El tautómero dicetona de la AB contiene dos restos fenacilo, que es un grupo protector fotolábil muy establecido. Por lo tanto, un diseño juicioso de una díada profármaco/profiltro permite la fotoliberación del fármaco y de su protector, la AB. La viabilidad de esta liberación controlada de los ingredientes se verificó en diferentes disolventes con carácter dador de H y viscosidad para simular la formulación tópica. Además, los estudios de fotólisis de destello láser en EtOH permiten la caracterización de una especie transitoria a 400-420 nm, la cual ha sido asignada al estado excitado triplete de AB-KP. Finalmente, se ha evaluado la fotoseguridad de la díada fotoactivable AB-KP. Los espectros de absorción transitoria de la díada AB-KP en ciclohexano muestra que la especie observada es el estado excitado triplete del KP y no el de la AB en su forma dicetona. El impacto de la díada sobre la membrana celular se ha abordado mediante irradiación UVA de soluciones de ácido linoleico en presencia de AB-KP y su potencial fototóxico se ha evidenciado mediante espectrofotometría UV-Vis revelando la formación de derivados hidroperóxidos diénicos conjugados del ácido linoleico. Sin embargo, la diada AB-KP no exhibe un potencial fotogenotóxico como lo demuestran los experimentos del ensayo comet, donde a diferencia del KP, la forma redonda no / The main objective of this thesis is to contrast the role of these 1,3-dicarbonyl compounds as DNA damaging agents to their photoprotective potential. Firstly, 5,6-dihydropyrimidines have been derivatized using a tert-butyl ketone photolabile group in order to study the generation of C5-centered radicals in non aqueous media. Then, laser flash photolysis study in acetonitrile of the designed 1,3-dicarbonyl derivatives yields the formation of the purported 5,6-dihydropyrimidin-5-yl radicals. Their characterization shows long lived transient species, which do not decay in the µs range and are centered at 400-420 nm or 350-400 nm for the 5,6-dihydrouridine or 5,6-dihydrothymidine derivatives, respectively. Moreover, radical generation has also been evidenced by steady state fluorescence experiments by using a profluorescent radical trap (AAA-TEMPO). Thus, irradiation of the photolabile nucleic acid derivatives in the presence of AAA-TEMPO results in an increased emission, in agreement with the trapping of C5 radical by the paramagnetic probe. Formation of the resulting adduct has been confirmed by UPLC-HRMS. Experimental data have been corroborated with ab initio CASPT2//CASSCF theoretical calculations. In a second chapter, another 1,3-dicarbonyl derivative of pyrimidine has been investigated. Indeed, 5-formyluracil (ForU) presents interesting features as a potential intrinsic DNA photosensitizing agent. Thus, spectroscopic studies reveal that ForU has not only an absorption in the UVA/UVB range, but also a triplet excited state (3ForU*) with a lifetime of some micros and with an energy high enough to photosensitize the well-known cyclobutane pyrimidine dimers (CPDs) through triplet-triplet energy transfer. This process has been confirmed by means of the synthesis of model Thy-Thy and Cyt-Cyt dyads, which after irradiation in the presence of ForU have been demonstrated to produce CPDs. Finally, the study extended to plasmid DNA allows establishing the ability of ForU to produce single strand breaks and CPDs. Next, the attention has been focused on the development of a new strategy for photoprotection of bioactive molecules taking advantage of the photochemical reactivity of the 1,3-diketo tautomer of the UVA filter avobenzone (AB). The selected bioactive compounds are two photosensitive topical non steroidal anti-inflammatory drugs, (S)-ketoprofen (KP) and diclofenac (DF). In this context, the diketo tautomer of avobenzone contains two phenacyl moieties, which are well-known photoremovable protecting groups. Thus, a judicious design of a pro-drug/pro-filter dyad allows the photorelease of the drug and its protecting shield, avobenzone. The viability of this controlled release of the active ingredients was checked in different solvents of different H donating properties and viscosity to simulate topical formulation.Plus, laser flash photolysis studies in ethanol allow characterization of a transient absorption band at 400-420 nm assigned to the triplet excited state of the dyad by comparison with that of the diketo form of AB. Finally, the photosafety of the photoactivatable AB-KP dyad has been assessed. The transient absorption spectra obtained for AB-KP dyad in cyclohexane showed the triplet excited state of KP and not that of the AB in its diketo form. The impact on the cellular membrane has been addressed by UVA irradiation of linoleic acid solutions in the presence of the dyad. Phototoxic potential of the dyad has been evidenced by UV-Vis spectrophotometry through the formation of the conjugated dienic hydroperoxides derived from linoleic acid. However, AB-KP does not exhibit a photogenotoxic potential as demonstrated by comet assay experiments, where by contrast with KP, the non damaged round shape of the cell is still observed after UVA irradiation. / L'objectiu principal d'aquesta tesi és contrastar el paper d'aquests compostos 1,3-dicarbonil com a agents que danyen l'ADN respecte al seu potencial fotoprotector. En primer lloc, 5,6-dihidropirimidines han sigut derivatitzades utilitzant el grup fotolàbil t-Bu cetona amb la finalitat d'estudiar la generació de radicals centrats en C5 en un mitjà no aquós. Després, l'estudi de fotòlisi de flaix làser en acetonitril dels derivats 1,3-dicarbonil dissenyats produeix la formació dels suposats radicals 5,6-dihidropirimidin-5-il. La seua caracterització mostra espècies transitòries de vida llarga i estan centrats a 400-420 nm o 350-400 nm per als derivats 5,6-dihidrouridina o 5,6-dihidrotimidina, respectivament. Per tant, la irradiació dels derivats fotolàbils d'àcid nucleic en presència de AAA-TEMPO dóna com resultat un augment de l'emissió, d'acord amb la captura del radical C5 per la sonda paramagnètica. La formació del adducte resultant s'ha confirmat mitjançant UPLC-HRMS. Així mateix, les dades experimentals s'han corroborat amb càlculs teòrics ab initio CASPT2 // CASSCF. En un segon capítol, un altre derivat 1,3-dicarbonil de la pirimidina ha sigut investigat. De fet, el dany 5-formiluracil (ForU), presenta característiques interessants com a potencial fotosensibilitzador intrínsec de l'ADN. Per tant, els estudis espectroscòpics revelen que ForU té una absorció en el rang UVA/UVB i també presenta un estat triplet excitat (3ForU*) amb un temps de vida d'alguns micros i amb una ET prou alta com per a fotosensibilitzar la formació dels coneguts dímers de pirimidina de tipus ciclobutà (CPDs) a través d'una transferència d'energia triplet-triplet. Aquest procés ha sigut confirmat per mitjà de la síntesi de diades model Thy-Thy i Cyt-Cyt, que després de la irradiació en presència de ForU s'ha demostrat que produeixen CPDs. Finalment, l'estudi en ADN plasmídic ha permès establir la capacitat de ForU per a produir trencaments de cadena simple i CPDs. A continuació, s'ha desenvolupat una nova estratègia per a la fotoprotecció de molècules bioactives aprofitant la reactivitat fotoquímica del tautòmer 1,3-dicetona del filtre de l'UVA Avobenzone (AB). Els compostos seleccionats són dos fàrmacs antiinflamatoris no esteroïdals d'ús tòpic amb propietats fotosensibilizants, (S)-ketoprofè (KP) i diclofenac (DF). En aquest context, el tautòmer dicetona de l'AB conté dues fraccions fenacil, que es un grup protector fotolàbil ben conegut. Per tant, un disseny judiciós d'una diada profàrmac / profiltre permet el fotoalliberament del fàrmac i del seu escut protector, l'AB. La viabilitat d'aquest alliberament controlat dels ingredients actius s'ha verificat en diferents dissolvents de diferent caràcter dador d'hidrogen i viscositat per a simular la formulació tòpica. A més, els estudis de fotòlisi de flaix làser en EtOH permeten la caracterització d'una banda d'absorció transitòria a 400-420 nm, la qual ha sigut assignada a l'estat excitat triplet de AB-KP. Finalment, s'ha avaluat la fotoseguretat de la diada fotoactivable AB-KP. Els espectres d'absorció transitòria de la diada AB-KP en ciclohexà mostres que l'espècie observada és l'estat excitat triplet del KP i no el de la AB en la seua forma dicetònica. L'impacte sobre la membrana cel·lular s'ha abordat mitjançant la irradiació UVA de solucions d'àcid linoleic en presència de AB-KP. El potencial fototòxic de la diada s'ha evidenciat mitjançant espectrofotometria UV-Vis revelant la formació de derivats hidroperòxids diènics conjugats de l'àcid linoleic. No obstant açò, la diada AB-KP no exhibeix un potencial fotogenotòxic com ho demostren els experiments de l'assaig comet, on a diferència del KP, la forma redona no danyada de la cèl·lula encara s'observa després de la irradiació UVA. / Aparici Espert, MI. (2018). Photochemistry of 1,3-Dicarbonyl Compounds: DNA Photodamage vs. Photoprotection [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/105782

The Small Cab-like Proteins (SCPs) in the cyanobacterium Synechocystis sp. PCC 6803 accumulate in cells grown under different stress conditions. Genes coding for SCPs have been found in all sequenced organisms performing oxygenic photosynthesis and even in the genomes of cyanophages. Deletion of multiple scp genes in Synechocystis resulted in mutants with severely impaired growth and altered pigment content. These findings indicate the importance of SCPs in photosynthesis; however, their specific function is not well understood. SCPs share a chlorophyll-binding motif with the plant light harvesting complex, suggesting that they bind chlorophyll. Here I describe my findings, which unambiguously show that SCPs are able to bind chlorophyll in vitro. Although they affect both the stoichiometric ratio of Photosystem I to II and chlorophyll stability, they do not seem to be directly involved in non-photochemical quenching. I was able to reveal the location of the SCPs within the cyanobacterial cell: in stressed cells they attach to Photosystem II in the thylakoid membrane. Furthermore, I revealed the presence of another light-harvesting like (Lil)/SCP protein in Synechocystis sp. PCC 6803. The gene, slr1544, codifying for this newly characterised LilA protein, co-transcribes together with scpD and also appears to bind to Photosystem II during stress.

Comme presque tous les êtres vivants, les insectes et autres arthropodes terrestres évoluent dans des environnements dynamiques et hétérogènes relativement à de multiples facteurs abiotiques incluant le rayonnement ultraviolet (UV). L’absorption de ces photons peut affecter le fitness des individus à travers différents types d’effets physiologiques et comportementaux. Certaines stratégies de lutte intégrée manipulent l’exposition au rayonnement UV en contexte agricole de façon à prendre avantage de son aspect attractif pour de nombreux ravageurs et de leur susceptibilité aux photodommages qu’il induit. Considérant le manque de connaissances sur les conséquences potentielles de telles approches sur les ennemis naturels, j’ai étudié dans cette thèse l’influence du rayonnement UV au fil du cycle de vie de deux espèces de guêpes parasitoïdes d’œufs, Telenomus podisi Ashmead, 1893 et Trissolcus utahensis Ashmead, 1893 (Hymenoptera : Scelionidae), et d’une de leurs punaises hôtes, Podisus maculiventris (Say, 1832) (Hemiptera : Pentatomidae), une espèce prédatrice qui pond des œufs de différents niveaux de pigmentation photoprotectrice. De façon à examiner divers paramètres d’histoire de vie de ces associations hôtes-parasitoïdes ainsi que certains des comportements liés à la recherche et à l’exploitation d’hôtes chez les parasitoïdes, j’ai réalisé une série d’expériences sous exposition naturelle et artificielle au rayonnement UV à l’aide de matériaux transmettant ou absorbant ces photons. Je démontre qu’une exposition réaliste au rayonnement UV peut entraîner des conséquences négatives sur le fitness des punaises et de leurs parasitoïdes d’œufs, et ce qu’ils y soient exposés durant leur développement ou comme adultes. L’exposition soutenue à un rayonnement UV-A de faible intensité a réduit la survie et la longévité des parasitoïdes adultes, tandis que chez les punaises, elle a induit des effets reportés négatifs sur la survie des nymphes jusqu’au stade adulte. Les conséquences immédiates et ultérieures de l’exposition des œufs de P. maculiventris au rayonnement UV ont été atténuées avec l’augmentation de leur niveau de pigmentation, et ce tant pour l’hôte que son parasitoïde. Au niveau comportemental, j’ai décrit comment les microhabitats exposés au rayonnement UV attirent les femelles parasitoïdes tout en réduisant leur activité locomotrice. Néanmoins, un taux de parasitisme élevé a été observé à diverses intensités d’exposition au rayonnement UV sur des plants de soya en cages de terrain, révélant que l’atténuation de ces signaux ne réduit pas nécessairement la performance de mes parasitoïdes. Dans l’ensemble, ces différentes études expérimentales ont révélé des effets similaires du rayonnement UV chez les trois espèces testées. Elles fournissent d’importantes réponses quant aux interactions complexes entre des insectes bénéfiques et un facteur abiotique associé aux changements climatiques et qui agit simultanément comme source de stress et d’information relativement à l’environnement. / Like most living things, insects and other terrestrial arthropods navigate environments that are dynamic and heterogenous with regards to various abiotic factors including ultraviolet (UV) radiation. Absorbing those photons can affect arthropod fitness via different types of physiological and behavioural effects. Some integrated pest management strategies manipulate UV exposure in agricultural settings to take advantage of its attractiveness to pests and of their susceptibility to UV damage. Considering the lack of knowledge on how such techniques could affect natural enemies, I studied the influence of UV radiation throughout the lifecycles of two egg parasitoid species, Telenomus podisi Ashmead, 1893 and Trissolcus utahensis Ashmead, 1893 (Hymenoptera: Scelionidae), and one of their potential stink bug hosts, Podisus maculiventris (Say, 1832) (Hemiptera: Pentatomidae), a predatory species that lays eggs of different photoprotective qualities. To examine various life history parameters in these host-parasitoid associations as well as some of the parasitoids’ host location and exploitation behaviours, I conducted a series of experiments under natural and artificial UV exposure, using UV-transmitting and UV-absorbing materials. I showed that realistic doses of UV radiation can have negative consequences for the fitness of stink bugs and their egg parasitoids, whether they were exposed during their development or their adult stage. Long-term exposure to mild UV-A intensities reduced parasitoid emergence and longevity, while inducing negative carryover effects on stink bug nymph survival to adulthood. Immediate or delayed consequences of exposing P. maculiventris eggs to UV radiation lessened with increasing egg pigmentation levels, both for the hosts and their parasitoids. As for behavioural responses to UV radiation, UV-exposed microhabitats were attractive to foraging female parasitoids but also reduced their walking activity. Nonetheless, high parasitism rates were observed under different intensities of UV exposure on soybean plants in field cages, revealing that UV attenuation does not necessarily impede these parasitoids’ performance. Together, these different experimental studies revealed similar effects of UV radiation on the three species tested. They provide important insight on the complex interactions between beneficial insects and an abiotic factor that is involved in climate change and that can act both as an environmental hazard and a visual cue.