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Lucock MD. The evolution of human skin pigmentation: A changing medley of vitamins, genetic variability, and UV radiation during human expansion. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2023; 180:252-271. [PMID: 36790744 PMCID: PMC10083917 DOI: 10.1002/ajpa.24564] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 05/19/2022] [Accepted: 05/25/2022] [Indexed: 04/12/2023]
Abstract
This review examines putative, yet likely critical evolutionary pressures contributing to human skin pigmentation and subsequently, depigmentation phenotypes. To achieve this, it provides a synthesis of ideas that frame contemporary thinking, without limiting the narrative to pigmentation genes alone. It examines how geography and hence the quality and quantity of UV exposure, pigmentation genes, diet-related genes, vitamins, anti-oxidant nutrients, and cultural practices intersect and interact to facilitate the evolution of human skin color. The article has a strong focus on the vitamin D-folate evolutionary model, with updates on the latest biophysical research findings to support this paradigm. This model is examined within a broad canvas that takes human expansion out of Africa and genetic architecture into account. A thorough discourse on the biology of melanization is provided (includes relationship to BH4 and DNA damage repair), with the relevance of this to the UV sensitivity of folate and UV photosynthesis of vitamin D explained in detail, including the relevance of these vitamins to reproductive success. It explores whether we might be able to predict vitamin-related gene polymorphisms that pivot metabolism to the prevailing UVR exposome within the vitamin D-folate evolutionary hypothesis context. This is discussed in terms of a primary adaptive phenotype (pigmentation/depigmentation), a secondary adaptive phenotype (flexible metabolic phenotype based on vitamin-related gene polymorphism profile), and a tertiary adaptive strategy (dietary anti-oxidants to support the secondary adaptive phenotype). Finally, alternative evolutionary models for pigmentation are discussed, as are challenges to future research in this area.
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Affiliation(s)
- Mark D. Lucock
- School of Environmental & Life SciencesUniversity of NewcastleOurimbahNew South WalesAustralia
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2
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Pouriayevali F, Tavalaee M, Taktaz-Hafshejani T, Dattilio M, Nasr-Esfahani MH. Overlapping sperm damages from vitamin B or D deficiency in mice: Insights into the role of clinical supplementations. Andrologia 2022; 54:e14592. [PMID: 36123798 DOI: 10.1111/and.14592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Revised: 08/24/2022] [Accepted: 08/31/2022] [Indexed: 11/29/2022] Open
Abstract
In this study, the effect of 14 weeks of standard diet (controls) or folate and vitamin B12-free diet (VBD group) or vitamin D-free diet (VDD group) were assessed on mice testicular function, and sperm function. Vitamin D deprivation caused increased body weight with no effect from VBD confirming the calcium-independent role of vitamin D on body weight homeostasis. The two deprivations caused convergent damages including decreased testosterone, worsened Johnson scores, tubular differentiation index and spermatogenesis index, and serious worsening of sperm parameters and of sperm functional tests (DNA methylation, protamination, DNA damage and lipid peroxidation). From a metabolic point of view, the damage from both models converged on the one carbon cycle (methylations) and the transsulfuration pathway (GSH and antioxidant defences) and increased circulating homocysteine, although with different mechanisms: VBD appeared to hamper methylations due to lower ability to regenerate homocysteine to methionine whereas VDD appeared to interfere with homocysteine transsulfuration to cysteine and, thereafter, GSH. VDD also caused a huge paradox increase of vitamin B12, which was likely in a non-functional form and warrants further investigation. These findings strongly endorse the potential benefit of combined folate/B12 and vitamin D supplementation in infertile patients.
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Affiliation(s)
- Farnaz Pouriayevali
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Shahrekord Branch, Islamic Azad University, Shahrekord, Iran.,Department of Animal Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, Isfahan, Iran
| | - Marziyeh Tavalaee
- Department of Animal Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, Isfahan, Iran
| | - Taghi Taktaz-Hafshejani
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Shahrekord Branch, Islamic Azad University, Shahrekord, Iran
| | | | - Mohammad H Nasr-Esfahani
- Department of Animal Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, Isfahan, Iran
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Tang JS, Cait A, White RM, Arabshahi HJ, O’Sullivan D, Gasser O. MR1-dependence of unmetabolized folic acid side-effects. Front Immunol 2022; 13:946713. [PMID: 36016938 PMCID: PMC9395688 DOI: 10.3389/fimmu.2022.946713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 07/21/2022] [Indexed: 11/28/2022] Open
Abstract
The fortification of flour with folic acid for the prevention of neural tube defects (NTD) is currently mandated in over eighty countries worldwide, hence compelling its consumption by the greater part of the world’s population. Notwithstanding its beneficial impact on rates of NTD, pervasive folic acid supplementation has invariably led to additive daily intakes reaching well beyond their original target, resulting in the circulation of unmetabolized folic acid. Associated idiopathic side-effects ranging from allergies to cancer have been suggested, albeit inconclusively. Herein, we hypothesize that their inconsistent detection and elusive etiology are linked to the in vivo generation of the immunosuppressive folic acid metabolite 6-formylpterin, which interferes with the still emerging and varied functions of Major Histocompatibility Complex-related molecule 1 (MR1)-restricted T cells. Accordingly, we predict that fortification-related adverse health outcomes can be eliminated by substituting folic acid with the bioequivalent folate vitamer 5-methyltetrahydrofolate, which does not break down into 6-formylpterin.
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Affiliation(s)
- Jeffry S. Tang
- Malaghan Institute of Medical Research, Wellington, New Zealand
- High-Value Nutrition National Science Challenge, Auckland, New Zealand
| | - Alissa Cait
- Malaghan Institute of Medical Research, Wellington, New Zealand
| | - Reuben M. White
- School of Chemical Sciences, University of Auckland, Auckland, New Zealand
| | | | - David O’Sullivan
- Malaghan Institute of Medical Research, Wellington, New Zealand
- High-Value Nutrition National Science Challenge, Auckland, New Zealand
| | - Olivier Gasser
- Malaghan Institute of Medical Research, Wellington, New Zealand
- High-Value Nutrition National Science Challenge, Auckland, New Zealand
- *Correspondence: Olivier Gasser,
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Dozova N, Lacombat F, Lombard M, Hamdane D, Plaza P. Ultrafast dynamics of fully reduced flavin in catalytic structures of thymidylate synthase ThyX. Phys Chem Chem Phys 2021; 23:22692-22702. [PMID: 34605505 DOI: 10.1039/d1cp03379d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Thymidylate is a vital DNA precursor synthesized by thymidylate synthases. ThyX is a flavin-dependent thymidylate synthase found in several human pathogens and absent in humans, which makes it a potential target for antimicrobial drugs. This enzyme methylates the 2'-deoxyuridine 5'-monophosphate (dUMP) to 2'-deoxythymidine 5'-monophosphate (dTMP) using a reduced flavin adenine dinucleotide (FADH-) as prosthetic group and (6R)-N5,N10-methylene-5,6,7,8-tetrahydrofolate (CH2THF) as a methylene donor. Recently, it was shown that ThyX-catalyzed reaction is a complex process wherein FADH- promotes both methylene transfer and reduction of the transferred methylene into a methyl group. Here, we studied the dynamic and photophysics of FADH- bound to ThyX, in several substrate-binding states (no substrate, in the presence of dUMP or folate or both) by femtosecond transient absorption spectroscopy. This methodology provides valuable information about the ground-state configuration of the isoalloxazine moiety of FADH- and the rigidity of its local environment, through spectra shape and excited-state lifetime parameters. In the absence of substrate, the environment of FADH- in ThyX is only mildly more constrained than that of free FADH- in solution. The addition of dUMP however narrows the distribution of ground-state configurations and increases the constraints on the butterfly bending motion in the excited state. Folate binding results in the selection of new ground-state configurations, presumably located at a greater distance from the conical intersection where excited-state decay occurs. When both substrates are present, the ground-state configuration appears on the contrary rather limited to a geometry close to the conical intersection, which explains the relatively fast excited-state decay (100 ps on the average), even if the environment of the isoalloxazine is densely packed. Hence, although the environment of the flavin is dramatically constrained, FADH- retains a dynamic necessary to shuttle carbon from folate to dUMP. Our study demonstrates the high sensitivity of FADH- photophysics to the constraints exerted by its immediate surroundings.
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Affiliation(s)
- Nadia Dozova
- PASTEUR, Département de chimie, École normale supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France.
| | - Fabien Lacombat
- PASTEUR, Département de chimie, École normale supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France.
| | - Murielle Lombard
- Laboratoire de Chimie des Processus Biologiques, CNRS-UMR 8229, Collège de France, Sorbonne Université, 75005 Paris, France.
| | - Djemel Hamdane
- Laboratoire de Chimie des Processus Biologiques, CNRS-UMR 8229, Collège de France, Sorbonne Université, 75005 Paris, France.
| | - Pascal Plaza
- PASTEUR, Département de chimie, École normale supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France.
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Lucock MD, Jones PR, Veysey M, Thota R, Garg M, Furst J, Martin C, Yates Z, Scarlett CJ, Jablonski NG, Chaplin G, Beckett EL. Biophysical evidence to support and extend the vitamin D-folate hypothesis as a paradigm for the evolution of human skin pigmentation. Am J Hum Biol 2021; 34:e23667. [PMID: 34418235 DOI: 10.1002/ajhb.23667] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 07/28/2021] [Accepted: 07/29/2021] [Indexed: 12/15/2022] Open
Abstract
OBJECTIVE To test the "vitamin D-folate hypothesis for the evolution of human skin pigmentation." METHODS Total ozone mapping spectrometer (TOMS) satellite data were used to examine surface UV-irradiance in a large (n = 649) Australian cross-sectional study population. Genetic analysis was used to score vitamin D- and folate-related gene polymorphisms (n = 22), along with two pigmentation gene variants (IRF4-rs12203592/HERC2-rs12913832). Red cell folate and vitamin D3 were measured by immunoassay and HPLC, respectively. RESULTS Ultraviolet radiation (UVR) and pigmentation genes interact to modify blood vitamin levels; Light skin IRF4-TT genotype has greatest folate loss while light skin HERC2-GG genotype has greatest vitamin D3 synthesis (reflected in both TOMS and seasonal data). UV-wavelength exhibits a dose-response relationship in folate loss within light skin IRF4-TT genotype (305 > 310 > 324 > 380 nm). Significant vitamin D3 photosynthesis only occurs within light skin HERC2-GG genotype, and is maximal at 305 nm. Three dietary antioxidants (vitamins C, E, and β-carotene) interact with UVR and pigmentation genes preventing oxidative loss of labile reduced folate vitamers, with greatest benefit in light skin IRF4-TT subjects. The putative photosensitiser, riboflavin, did not sensitize red cell folate to UVR and actually afforded protection. Four genes (5xSNPs) influenced blood vitamin levels when stratified by pigmentation genotype; MTHFR-rs1801133/rs1801131, TS-rs34489327, CYP24A-rs17216707, and VDR-ApaI-rs7975232. Lightest IRF4-TT/darkest HERC2-AA genotype combination (greatest folate loss/lowest vitamin D3 synthesis) has 0% occurrence. The opposing, commonest (39%) compound genotype (darkest IRF4-CC/lightest HERC2-GG) permits least folate loss and greatest synthesis of vitamin D3 . CONCLUSION New biophysical evidence supports the vitamin D-folate hypothesis for evolution of skin pigmentation.
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Affiliation(s)
- Mark D Lucock
- School of Environmental and Life Sciences, University of Newcastle, Ourimbah, New South Wales, Australia
| | - Patrice R Jones
- School of Environmental and Life Sciences, University of Newcastle, Ourimbah, New South Wales, Australia
| | | | - Rohith Thota
- Nutraceuticals Research Group, University of Newcastle, Callaghan, New South Wales, Australia.,Metabolism and Nutrition, Riddet Institute, Massey University, Palmerston North, New Zealand
| | - Manohar Garg
- Nutraceuticals Research Group, University of Newcastle, Callaghan, New South Wales, Australia
| | - John Furst
- Maths and Physical Sciences, University of Newcastle, Ourimbah, New South Wales, Australia
| | - Charlotte Martin
- School of Environmental and Life Sciences, University of Newcastle, Ourimbah, New South Wales, Australia
| | - Zoe Yates
- Biomedical Sciences and Pharmacy, University of Newcastle, Ourimbah, New South Wales, Australia
| | - Christopher J Scarlett
- School of Environmental and Life Sciences, University of Newcastle, Ourimbah, New South Wales, Australia
| | - Nina G Jablonski
- Anthropology Department, The Pennsylvania State University, University Park, Pennsylvania, USA
| | - George Chaplin
- Anthropology Department, The Pennsylvania State University, University Park, Pennsylvania, USA
| | - Emma L Beckett
- School of Environmental and Life Sciences, University of Newcastle, Ourimbah, New South Wales, Australia
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Serebrova VN, Trifonova EA, Stepanov VA. Pregnancy as a Factor of Adaptive Human Evolution. The Role of Natural Selection in the Origin of Preeclampsia. RUSS J GENET+ 2021. [DOI: 10.1134/s1022795421010142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Environmental UVR Levels and Skin Pigmentation Gene Variants Associated with Folate and Homocysteine Levels in an Elderly Cohort. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17051545. [PMID: 32121219 PMCID: PMC7084217 DOI: 10.3390/ijerph17051545] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 02/26/2020] [Accepted: 02/26/2020] [Indexed: 12/15/2022]
Abstract
Ultraviolet radiation (UVR) is a ubiquitous exposure which may contribute to decreased folate levels. Skin pigmentation mediates the biological effect of UVR exposure, but its relationship to folate levels is unexamined. Interactions may exist between UVR and pigmentation genes in determining folate status, which may, in turn, impact homocysteine levels, a potential risk factor for multiple chronic diseases. Therefore, independent and interactive influences of environmental UVR and genetic variants related to skin pigmentation (MC1R-rs1805007, IRF4-rs12203592 and HERC2-rs12913832) on folate (red blood cell (RBC) and serum) and homocysteine levels were examined in an elderly Australian cohort (n = 599). Genotypes were assessed by RT/RFLP-PCR, and UVR exposures were assessed as the accumulated erythemal dose rate accumulated over 4 months (4M-EDR). Multivariate analysis found significant negative associations between 4M-EDR and RBC folate (p < 0.001, β = −0.19), serum folate (p = 0.045, β = −0.08) and homocysteine levels (p < 0.001, β = −0.28). Significant associations between MC1R-rs1805007 and serum folate levels (p = 0.020), and IRF4-rs12203592 and homocysteine levels (p = 0.026) occurred but did not remain significant following corrections with confounders. No interactions between 4M-EDR and pigmentation variants in predicting folate/homocysteine levels were found. UVR levels and skin pigmentation-related variants are potential determinants of folate and homocysteine status, although, associations are mixed and complex, with further studies warranted.
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Lin T, Man M, Abuabara K, Wakefield JS, Sheu H, Tsai J, Lee C, Elias PM. By protecting against cutaneous inflammation, epidermal pigmentation provided an additional advantage for ancestral humans. Evol Appl 2019; 12:1960-1970. [PMID: 31700538 PMCID: PMC6824065 DOI: 10.1111/eva.12858] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 07/30/2019] [Accepted: 08/14/2019] [Indexed: 12/30/2022] Open
Abstract
Pigmentation evolved in ancestral humans to protect against toxic, ultraviolet B irradiation, but the question remains: "what is being protected?" Because humans with dark pigmentation display a suite of superior epidermal functions in comparison with their more lightly pigmented counterparts, we hypothesized and provided evidence that dark pigmentation evolved in Africa to support cutaneous function. Because our prior clinical studies also showed that a restoration of a competent barrier dampens cutaneous inflammation, we hypothesized that resistance to inflammation could have provided pigmented hominins with yet another, important evolutionary benefit. We addressed this issue here in two closely related strains of hairless mice, endowed with either moderate (Skh2/J) or absent (Skh1) pigmentation. In these models, we showed that (a) pigmented mice display a markedly reduced propensity to develop inflammation after challenges with either a topical irritant or allergen in comparison with their nonpigmented counterparts; (b) visible and histologic evidence of inflammation was paralleled by reduced levels of pro-inflammatory cytokines (i.e., IL-1α and INFα); (c) because depigmentation of Skh2/J mouse skin enhanced both visible inflammation and pro-inflammatory cytokine levels after comparable pro-inflammatory challenges, the reduced propensity to develop inflammation was directly linked to the presence of pigmentation; and (d) furthermore, in accordance with our prior work showing that pigment production endows benefits by reducing the surface pH of skin, acidification of albino (Skh1) mouse skin also protected against inflammation, and equalized cytokine levels to those found in pigmented skin. In summary, pigmentation yields a reduced propensity to develop inflammation, consistent with our hypothesis that dark pigmentation evolved in ancestral humans to provide a suite of barrier-linked benefits that now include resistance to inflammation.
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Affiliation(s)
- Tzu‐Kai Lin
- Department of DermatologyHualien Tzu Chi HospitalBuddhist Tzu Chi Medical FoundationHualienTaiwan
- School of MedicineTzu Chi UniversityHualienTaiwan
| | - Mao‐Qiang Man
- Department of DermatologyVA Med Ctr/UCSFSan FranciscoCalifornia
| | - Katrina Abuabara
- Program for Clinical ResearchDepartment of DermatologyUC San Francisco School of MedicineSan FranciscoCalifornia
| | | | - Hamm‐ming Sheu
- Department of DermatologyNational Cheng Kung University College of MedicineTainanTaiwan
| | - Jui‐chen Tsai
- Institute of Clinical Pharmacy and Biopharmaceutical SciencesCollege of MedicineNational Cheng Kung UniversityTainanTaiwan
| | - Chih‐Hung Lee
- Department of DermatologyKaohsiung Chang Gung Memorial Hospital and Chang Gung University College of MedicineKaohsiungTaiwan
| | - Peter M. Elias
- Department of DermatologyVA Med Ctr/UCSFSan FranciscoCalifornia
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The Vitamin D⁻Folate Hypothesis as an Evolutionary Model for Skin Pigmentation: An Update and Integration of Current Ideas. Nutrients 2018; 10:nu10050554. [PMID: 29710859 PMCID: PMC5986434 DOI: 10.3390/nu10050554] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 04/27/2018] [Accepted: 04/27/2018] [Indexed: 12/24/2022] Open
Abstract
Vitamin D is unique in being generated in our skin following ultraviolet radiation (UVR) exposure. Ongoing research into vitamin D must therefore always consider the influence of UVR on vitamin D processes. The close relationship between vitamin D and UVR forms the basis of the “vitamin D–folate hypothesis”, a popular theory for why human skin colour has evolved as an apparent adaption to UVR environments. Vitamin D and folate have disparate sensitivities to UVR; whilst vitamin D may be synthesised following UVR exposure, folate may be degraded. The vitamin D–folate hypothesis proposes that skin pigmentation has evolved as a balancing mechanism, maintaining levels of these vitamins. There are several alternative theories that counter the vitamin D–folate hypothesis. However, there is significant overlap between these theories and the now known actions of vitamin D and folate in the skin. The focus of this review is to present an update on the vitamin D–folate hypothesis by integrating these current theories and discussing new evidence that supports associations between vitamin D and folate genetics, UVR, and skin pigmentation. In light of recent human migrations and seasonality in disease, the need for ongoing research into potential UVR-responsive processes within the body is also discussed.
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Jones P, Lucock M, Veysey M, Jablonski N, Chaplin G, Beckett E. Frequency of folate-related polymorphisms varies by skin pigmentation. Am J Hum Biol 2017; 30. [DOI: 10.1002/ajhb.23079] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 09/27/2017] [Accepted: 10/29/2017] [Indexed: 12/12/2022] Open
Affiliation(s)
- Patrice Jones
- School of Environmental & Life Sciences, University of Newcastle; Ourimbah NSW Australia
| | - Mark Lucock
- School of Environmental & Life Sciences, University of Newcastle; Ourimbah NSW Australia
| | - Martin Veysey
- Hull-York Medical School; University of York; Heslington York UK
| | - Nina Jablonski
- Anthropology Department; The Pennsylvania State University; Pennsylvania
| | - George Chaplin
- Anthropology Department; The Pennsylvania State University; Pennsylvania
| | - Emma Beckett
- School of Environmental & Life Sciences, University of Newcastle; Ourimbah NSW Australia
- School of Medicine and Public Health; University of Newcastle; Ourimbah NSW Australia
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Zhang M, Goyert G, Lim HW. Folate and phototherapy: What should we inform our patients? J Am Acad Dermatol 2017; 77:958-964. [DOI: 10.1016/j.jaad.2016.10.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 09/23/2016] [Accepted: 10/07/2016] [Indexed: 12/19/2022]
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Jablonski NG, Chaplin G. The colours of humanity: the evolution of pigmentation in the human lineage. Philos Trans R Soc Lond B Biol Sci 2017; 372:20160349. [PMID: 28533464 PMCID: PMC5444068 DOI: 10.1098/rstb.2016.0349] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/09/2016] [Indexed: 12/16/2022] Open
Abstract
Humans are a colourful species of primate, with human skin, hair and eye coloration having been influenced by a great variety of evolutionary forces throughout prehistory. Functionally naked skin has been the physical interface between the physical environment and the human body for most of the history of the genus Homo, and hence skin coloration has been under intense natural selection. From an original condition of protective, dark, eumelanin-enriched coloration in early tropical-dwelling Homo and Homo sapiens, loss of melanin pigmentation occurred under natural selection as Homo sapiens dispersed into non-tropical latitudes of Africa and Eurasia. Genes responsible for skin, hair and eye coloration appear to have been affected significantly by population bottlenecks in the course of Homo sapiens dispersals. Because specific skin colour phenotypes can be created by different combinations of skin colour-associated genetic markers, loss of genetic variability due to genetic drift appears to have had negligible effects on the highly redundant genetic 'palette' for the skin colour. This does not appear to have been the case for hair and eye coloration, however, and these traits appear to have been more strongly influenced by genetic drift and, possibly, sexual selection.This article is part of the themed issue 'Animal coloration: production, perception, function and application'.
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Affiliation(s)
- Nina G Jablonski
- Department of Anthropology, The Pennsylvania State University, 409 Carpenter Building, University Park, PA 16802, USA
| | - George Chaplin
- Department of Anthropology, The Pennsylvania State University, 409 Carpenter Building, University Park, PA 16802, USA
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Lucock M, Beckett E, Martin C, Jones P, Furst J, Yates Z, Jablonski NG, Chaplin G, Veysey M. UV‐associated decline in systemic folate: implications for human nutrigenetics, health, and evolutionary processes. Am J Hum Biol 2016; 29. [DOI: 10.1002/ajhb.22929] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 07/13/2016] [Accepted: 09/25/2016] [Indexed: 12/15/2022] Open
Affiliation(s)
- Mark Lucock
- School of Environmental and Life SciencesUniversity of NewcastlePO Box 127, Brush RdOurimbah NSW2258 Australia
| | - Emma Beckett
- School of Environmental and Life SciencesUniversity of NewcastlePO Box 127, Brush RdOurimbah NSW2258 Australia
| | - Charlotte Martin
- School of Environmental and Life SciencesUniversity of NewcastlePO Box 127, Brush RdOurimbah NSW2258 Australia
| | - Patrice Jones
- School of Environmental and Life SciencesUniversity of NewcastlePO Box 127, Brush RdOurimbah NSW2258 Australia
| | - John Furst
- School of Maths and Physical SciencesUniversity of NewcastlePO Box 127, Brush RdOurimbah NSW2258 Australia
| | - Zoe Yates
- School of Biomedical Sciences and PharmacyUniversity of NewcastlePO Box 127, Brush RdOurimbah NSW2258 Australia
| | - Nina G. Jablonski
- Anthropology DepartmentThe Pennsylvania State University409 Carpenter BuildingUniversity Park Pennsylvania16802
| | - George Chaplin
- Anthropology DepartmentThe Pennsylvania State University409 Carpenter BuildingUniversity Park Pennsylvania16802
| | - Martin Veysey
- School of Medicine and Public Health, University of Newcastle, NSW, 2308, Australia and, Central Coast Local Health DistrictTeaching and Research Unit, Gosford HospitalGosford NSW2250PO Box 361 Australia
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14
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Lucock M, Yates Z, Martin C, Choi JH, Boyd L, Tang S, Naumovski N, Furst J, Roach P, Jablonski N, Chaplin G, Veysey M. Vitamin D, folate, and potential early lifecycle environmental origin of significant adult phenotypes. EVOLUTION MEDICINE AND PUBLIC HEALTH 2014; 2014:69-91. [PMID: 24699387 PMCID: PMC4001294 DOI: 10.1093/emph/eou013] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Solar radiation early in pregnancy interacts with light sensitive vitamins to influence an embryo's genetic profile. This influences both adult disease risk and may play a role in the evolution of skin colour. Background and objectives: Vitamin D and folate are highly UV sensitive, and critical for maintaining health throughout the lifecycle. This study examines whether solar irradiance during the first trimester of pregnancy influences vitamin D receptor (VDR) and nuclear folate gene variant occurrence, and whether affected genes influence late-life biochemical/clinical phenotypes. Methodology: 228 subjects were examined for periconceptional exposure to solar irradiance, variation in vitamin D/folate genes (polymerase chain reaction (PCR)), dietary intake (food frequency questionnaire (FFQ)) and important adult biochemical/clinical phenotypes. Results: Periconceptional solar irradiance was associated with VDR-BsmI (P = 0.0008wk7), TaqI (P = 0.0014wk7) and EcoRV (P = 0.0030wk6) variant occurrence between post-conceptional weeks 6–8, a period when ossification begins. Similar effects were detected for other VDR gene polymorphisms. Periconceptional solar irradiance was also associated with 19 bp del-DHFR (P = 0.0025wk6), and to a lesser extent C1420T-SHMT (P = 0.0249wk6), a folate-critical time during embryogenesis. These same genes were associated with several late-life phenotypes: VDR-BsmI, TaqI and ApaI determined the relationship between dietary vitamin D and both insulin (P < 0.0001/BB, 0.0007/tt and 0.0173/AA, respectively) and systolic blood pressure (P = 0.0290/Bb, 0.0299/Tt and 0.0412/AA, respectively), making them important early and late in the lifecycle. While these and other phenotype associations were found for the VDR variants, folate polymorphism associations in later-life were limited to C1420T-SHMT (P = 0.0037 and 0.0297 for fasting blood glucose and HbA1c levels, respectively). We additionally report nutrient–gene relationships with body mass index, thiol/folate metabolome, cognition, depression and hypertension. Furthermore, photoperiod at conception influenced occurrence of VDR-Tru9I and 2R3R-TS genotypes (P = 0.0120 and 0.0360, respectively). Conclusions and implications: Findings identify environmental and nutritional agents that may interact to modify gene–phenotype relationships across the lifecycle, offering new insight into human ecology. This includes factors related to both disease aetiology and the evolution of skin pigmentation.
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Affiliation(s)
- Mark Lucock
- School of Environmental and Life Sciences, Biomedical Sciences and Pharmacy, Maths and Physical Sciences, University of Newcastle, PO Box 127, Brush Road, Ourimbah, NSW 2258, Australia, The Pennsylvania State University, Anthropology Department, 409 Carpenter Building, University Park, PA 16802, USA, and Teaching and Research Unit, Central Coast Local Health District, PO Box 361, Gosford, NSW 2250, Australia
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15
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Borradale D, Isenring E, Hacker E, Kimlin M. Exposure to solar ultraviolet radiation is associated with a decreased folate status in women of childbearing age. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2014; 131:90-5. [DOI: 10.1016/j.jphotobiol.2014.01.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 12/21/2013] [Accepted: 01/07/2014] [Indexed: 02/07/2023]
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16
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Jablonski NG, Chaplin G. The evolution of skin pigmentation and hair texture in people of African ancestry. Dermatol Clin 2013; 32:113-21. [PMID: 24679998 DOI: 10.1016/j.det.2013.11.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Our species, Homo sapiens, evolved in Africa, and humanity's highest levels of genetic diversity are maintained there today. Underlying genetic diversity combined with the great range of solar regimes and climatic conditions found in Africa has contributed to a wide range of human integumentary phenotypes within the continent. Millions of Africans have moved, voluntarily and involuntarily, to other continents in the past 2000 years, and the range of integumentary phenotypes among admixed African diaspora populations is enormous. In this contribution, we do not catalog this variation, but provide basic evolutionary background as to how it developed in the first place.
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Affiliation(s)
- Nina G Jablonski
- Department of Anthropology, The Pennsylvania State University, 409 Carpenter Building, University Park, PA 16802, USA.
| | - George Chaplin
- Department of Anthropology, The Pennsylvania State University, 409 Carpenter Building, University Park, PA 16802, USA; Department of Geography, The Pennsylvania State University, 409 Carpenter Building, University Park, PA 16802, USA
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17
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Jablonski NG, Chaplin G. Epidermal pigmentation in the human lineage is an adaptation to ultraviolet radiation. J Hum Evol 2013; 65:671-5. [DOI: 10.1016/j.jhevol.2013.06.004] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 05/13/2013] [Accepted: 06/01/2013] [Indexed: 11/29/2022]
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18
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Brown EA, Ruvolo M, Sabeti PC. Many ways to die, one way to arrive: how selection acts through pregnancy. Trends Genet 2013; 29:585-92. [DOI: 10.1016/j.tig.2013.03.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2012] [Revised: 02/15/2013] [Accepted: 03/08/2013] [Indexed: 01/24/2023]
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19
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Juzeniene A, Thu Tam TT, Iani V, Moan J. The action spectrum for folic acid photodegradation in aqueous solutions. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2013; 126:11-6. [DOI: 10.1016/j.jphotobiol.2013.05.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 05/08/2013] [Accepted: 05/29/2013] [Indexed: 12/14/2022]
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20
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UVB exposure of farm animals: study on a food-based strategy to bridge the gap between current vitamin D intakes and dietary targets. PLoS One 2013; 8:e69418. [PMID: 23894475 PMCID: PMC3722170 DOI: 10.1371/journal.pone.0069418] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 06/10/2013] [Indexed: 01/04/2023] Open
Abstract
Vitamin D deficiency is a global health problem. This study aimed to investigate the efficacy of ultraviolet (UV) B radiation for improving vitamin D3 content of eggs and meat. In a two-factorial design hens that received diets with 0 (-D3) or 3,000 IU (+D3) vitamin D3/kg were non-exposed (-UVB) or exposed to UVB radiation (+UVB) for 3 h daily over 4 weeks. Data show that UVB radiation was very effective in raising the vitamin D3 content of egg yolk and meat. Egg yolk from +UVB/−D3 hens had a higher vitamin D3 content (17.5±7.2 µg/100 g dry matter (DM)) than those from the –UVB/+D3 group (5.2±2.4 µg/100 g DM, p<0.01). Vitamin D3 content in egg yolk of vitamin D3-supplemented hens could be further increased by UVB radiation (32.4±10.9 µg/100 g DM). The content of 25-hydroxyvitamin D3 (25(OH)D3) in the egg yolk also increased in response to UVB, although less pronounced than vitamin D3. Meat revealed about 4-fold higher vitamin D3 contents in response to UVB than to dietary vitamin D3 (p<0.001). In conclusion, exposure of hens to UVB is an efficient approach to provide consumers with vitamin D3-enriched foods from animal sources.
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21
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Solar cycle predicts folate-sensitive neonatal genotypes at discrete phases of the first trimester of pregnancy: A novel folate-related human embryo loss hypothesis. Med Hypotheses 2012; 79:210-5. [DOI: 10.1016/j.mehy.2012.04.039] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 04/24/2012] [Accepted: 04/26/2012] [Indexed: 12/14/2022]
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22
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Borradale DC, Kimlin MG. Folate degradation due to ultraviolet radiation: possible implications for human health and nutrition. Nutr Rev 2012; 70:414-22. [DOI: 10.1111/j.1753-4887.2012.00485.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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23
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Moan J, Nielsen KP, Juzeniene A. Immediate pigment darkening: its evolutionary roles may include protection against folate photosensitization. FASEB J 2011; 26:971-5. [DOI: 10.1096/fj.11-195859] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Johan Moan
- Department of Radiation BiologyInstitute for Cancer ResearchNorwegian Radium HospitalOslo University HospitalMontebelloNorway
- Institute of PhysicsUniversity of OsloOsloNorway
| | | | - Asta Juzeniene
- Department of Radiation BiologyInstitute for Cancer ResearchNorwegian Radium HospitalOslo University HospitalMontebelloNorway
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24
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Simon RR, Phillips KM, Horst RL, Munro IC. Vitamin D mushrooms: comparison of the composition of button mushrooms (Agaricus bisporus) treated postharvest with UVB light or sunlight. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2011; 59:8724-8732. [PMID: 21736377 DOI: 10.1021/jf201255b] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
This study compared the compositional changes in mushrooms exposed to sunlight with those occurring after commercial ultraviolet (UV) light processing. Button mushrooms (75 kg) were processed in the presence or absence of UVB light; a third group was exposed to direct sunlight. Mushroom composition was evaluated using chemical analyses. Vitamin D concentrations were 5, 410, and 374 μg/100 g (dw) in control, UVB, and sunlight groups, respectively. On a dry weight basis, no significant changes in vitamin C, folate, vitamins B(6), vitamin B(5), riboflavin, niacin, amino acids, fatty acids, ergosterol, or agaritine were observed following UVB processing. Sunlight exposure resulted in a 26% loss of riboflavin, evidence of folate oxidation, and unexplained increases in ergosterol (9.5%). It was concluded that compositional effects of UVB light are limited to changes in vitamin D and show no detrimental changes relative to natural sunlight exposure and, therefore, provide important information relevant to the suitability and safety of UVB light technology for vitamin D enhanced mushrooms.
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Affiliation(s)
- Ryan R Simon
- Cantox Health Sciences International, an Intertek Company, Mississauga, Ontario, Canada.
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25
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Scurachio RS, Skibsted LH, Metzker G, Cardoso DR. Photodegradation of Folate Sensitized by Riboflavin. Photochem Photobiol 2011; 87:840-5. [DOI: 10.1111/j.1751-1097.2011.00916.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Regina S. Scurachio
- Instituto de Quimica de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, Brazil
| | - Leif H. Skibsted
- Food Chemistry, Department of Food Science, Faculty of Life Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Gustavo Metzker
- Instituto de Quimica de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, Brazil
| | - Daniel R. Cardoso
- Instituto de Quimica de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, Brazil
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26
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Juzeniene A, Stokke KT, Thune P, Moan J. Pilot study of folate status in healthy volunteers and in patients with psoriasis before and after UV exposure. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2010; 101:111-6. [DOI: 10.1016/j.jphotobiol.2010.01.013] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2009] [Revised: 01/22/2010] [Accepted: 01/30/2010] [Indexed: 02/06/2023]
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27
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Colloquium paper: human skin pigmentation as an adaptation to UV radiation. Proc Natl Acad Sci U S A 2010; 107 Suppl 2:8962-8. [PMID: 20445093 DOI: 10.1073/pnas.0914628107] [Citation(s) in RCA: 397] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Human skin pigmentation is the product of two clines produced by natural selection to adjust levels of constitutive pigmentation to levels of UV radiation (UVR). One cline was generated by high UVR near the equator and led to the evolution of dark, photoprotective, eumelanin-rich pigmentation. The other was produced by the requirement for UVB photons to sustain cutaneous photosynthesis of vitamin D(3) in low-UVB environments, and resulted in the evolution of depigmented skin. As hominins dispersed outside of the tropics, they experienced different intensities and seasonal mixtures of UVA and UVB. Extreme UVA throughout the year and two equinoctial peaks of UVB prevail within the tropics. Under these conditions, the primary selective pressure was to protect folate by maintaining dark pigmentation. Photolysis of folate and its main serum form of 5-methylhydrofolate is caused by UVR and by reactive oxygen species generated by UVA. Competition for folate between the needs for cell division, DNA repair, and melanogenesis is severe under stressful, high-UVR conditions and is exacerbated by dietary insufficiency. Outside of tropical latitudes, UVB levels are generally low and peak only once during the year. The populations exhibiting maximally depigmented skin are those inhabiting environments with the lowest annual and summer peak levels of UVB. Development of facultative pigmentation (tanning) was important to populations settling between roughly 23 degrees and 46 degrees , where levels of UVB varied strongly according to season. Depigmented and tannable skin evolved numerous times in hominin evolution via independent genetic pathways under positive selection.
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28
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Shapira N. Nutritional approach to sun protection: a suggested complement to external strategies. Nutr Rev 2010; 68:75-86. [PMID: 20137053 DOI: 10.1111/j.1753-4887.2009.00264.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The increasing incidence of skin cancer despite the use of externally applied sun protection strategies, alongside research showing that nutrients reduce photo-oxidative damage, suggest nutritional approaches could play a beneficial role in skin cancer prevention. Penetrating photo-oxidative ultraviolet A radiation reduces skin and blood antioxidants and damages cell components, including DNA. Dietary antioxidant vitamins, minerals, and phytochemicals in addition to n-3 polyunsaturated fatty acids, n-9 monounsaturated fatty acids, and low pro-inflammatory n-6 polyunsaturated fatty acids, have demonstrated protective properties. The presence of these elements in the traditional Greek-style Mediterranean diet may have contributed to the low rates of melanoma in the Mediterranean region despite high levels of solar radiation. This suggests a potentially relevant model for studying dietary/nutritional supplementation for lifelong internal support of sun-protection mechanisms, which could complement external strategies.
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Affiliation(s)
- Niva Shapira
- Stanley Steyer School of Health Professions, Tel Aviv University, Tel Aviv, Israel.
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29
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Damian DL, Matthews YJ, Halliday GM. Topical riboflavin attenuates ultraviolet B- and ultraviolet A-induced immunosuppression in humans. PHOTODERMATOLOGY PHOTOIMMUNOLOGY & PHOTOMEDICINE 2010; 26:66-9. [DOI: 10.1111/j.1600-0781.2010.00486.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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30
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Williams JD, Jacobson MK. Photobiological implications of folate depletion and repletion in cultured human keratinocytes. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2010; 99:49-61. [PMID: 20211567 DOI: 10.1016/j.jphotobiol.2010.02.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Revised: 01/27/2010] [Accepted: 02/02/2010] [Indexed: 12/15/2022]
Abstract
Folate nutrition is critical in humans and a high dietary folate intake is associated with a diminished risk of many types of cancer. Both synthetic folic acid and the most biologically abundant extracellular reduced folate, 5-methyltetrahydrofolate, are degraded under conditions of ultraviolet radiation (UVR) exposure. Skin is a proliferative tissue with increased folate nutrient demands due to a dependence upon continuous epidermal cell proliferation and differentiation to maintain homeostasis. Regions of skin are also chronically exposed to UVR, which penetrates to the actively dividing basal layer of the epidermis, increasing the folate nutrient demands in order to replace folate species degraded by UVR exposure and to supply the folate cofactors required for repair of photo-damaged DNA. Localized folate deficiencies of skin are a likely consequence of UVR exposure. We report here a cultured keratinocyte model of folate deficiency that has been applied to examine possible effects of folate nutritional deficiencies in skin. Utilizing this model, we were able to quantify the concentrations of key intracellular folate species during folate depletion and repletion. We investigated the hypotheses that the genomic instability observed under conditions of folate deficiency in other cell types extends to skin, adversely effecting cellular capacity to handle UVR insult and that optimizing folate levels in skin is beneficial in preventing or repairing the pro-carcinogenic effects of UVR exposure. Folate restriction leads to rapid depletion of intracellular reduced folates resulting in S-phase growth arrest, increased levels of inherent DNA damage, and increased uracil misincorporation into DNA, without a significant losses in overall cellular viability. Folate depleted keratinocytes were sensitized toward UVR induced apoptosis and displayed a diminished capacity to remove DNA breaks resulting from both photo and oxidative DNA damage. Thus, folate deficiency creates a permissive environment for genomic instability, an early event in the process of skin carcinogenesis. The effects of folate restriction, even in severely depleted, growth-arrested keratinocytes, were reversible by repletion with folic acid. Overall, these results indicate that skin health can be positively influenced by optimal folate nutriture.
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Affiliation(s)
- Joshua D Williams
- Medicinal and Natural Products Chemistry, Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Arizona Cancer Center, 1515 N. Campbell Ave., Tucson, AZ 85724, USA.
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31
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Cicarma E, Mørk C, Porojnicu AC, Juzeniene A, Tam TTT, Dahlback A, Moan J. Influence of narrowband UVB phototherapy on vitamin D and folate status. Exp Dermatol 2009; 19:e67-72. [DOI: 10.1111/j.1600-0625.2009.00987.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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32
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Juzeniene A, Thu Tam TT, Iani V, Moan J. 5-Methyltetrahydrofolate can be photodegraded by endogenous photosensitizers. Free Radic Biol Med 2009; 47:1199-204. [PMID: 19647791 DOI: 10.1016/j.freeradbiomed.2009.07.030] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Revised: 06/29/2009] [Accepted: 07/27/2009] [Indexed: 10/20/2022]
Abstract
Folate deficiency is linked to serious birth defects, pregnancy complications, male infertility, cardiovascular diseases, and even the evolution of human skin color. Conflicting data exist on whether exposure to sun or artificial UV sources may deplete the levels of blood folate in humans. Blood contains several photosensitizers and proteins, as well as antioxidants, which when exposed to UV radiation and visible light may be involved in the degradation of folate. In this study the photodegradation of 5-methyltetrahydrofolate (5MTHF) in aqueous and deuterious solutions exposed to UVB, UVA, or visible light in the absence or presence of riboflavin, uroporphyrin, and conjugated bilirubin was investigated by absorption spectroscopy. 5MTHF is stable under exposure to visible light and UVA radiation, whereas it is slowly photooxidized under UVB exposure. However, it is rapidly oxidized by UVA or visible radiation in the presence of riboflavin or uroporphyrin, but not in the presence of conjugated bilirubin, which acts in a protective manner. Reactive oxygen species produced in type I and/or type II reactions were involved. This study suggests that 5MTHF in blood can be photodegraded in the presence of the flavins and porphyrins, but protected by bilirubins. This may have health and evolutionary implications.
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Affiliation(s)
- Asta Juzeniene
- Department of Radiation Biology, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo University Hospital, Montebello, 0310 Oslo, Norway.
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33
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Tam TTT, Juzeniene A, Steindal AH, Iani V, Moan J. Photodegradation of 5-methyltetrahydrofolate in the presence of Uroporphyrin. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2008; 94:201-4. [PMID: 19138530 DOI: 10.1016/j.jphotobiol.2008.12.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2008] [Revised: 12/05/2008] [Accepted: 12/05/2008] [Indexed: 11/27/2022]
Abstract
The main form of folate in human plasma is 5-methyltetrahydrofolate (5MTHF). The observation that folate in human serum is photosensitive supports the hypothesis that humans developed dark skin in high ultraviolet fluences areas in order to protect folate in the blood from UV radiation. However, folates alone are quite photostable. Therefore, in this study, we examined for the first time the photodegradation of 5MTHF in the presence of the endogenous photosensitizer uroporphyrin (Uro), which is sometimes present in low concentration in human serum, under UV and near-UV light exposure. We found strong indications that while 5MTHF alone is rather photostable, it is degraded quickly in the presence of Uro. Using deuterium oxide (D(2)O) as an enhancer of the lifetime of singlet oxygen and the singlet oxygen sensor green reagent (SOSG) as a scavenger of singlet oxygen, we have found that the photodegradation most likely proceeds via a type II photosensitization. Our results show that singlet oxygen is likely to be the main intermediate in the photodegradation of 5MTHF mediated by Uro. Our findings may be useful for further studies the evolution of human skin colours.
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Affiliation(s)
- Tran Thi Thu Tam
- Department of Radiation Biology, Institute for Cancer Research, The Norwegian Radium Hospital, Rikshospitalet University Hospital, Montebello, N-0310 Oslo, Norway
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