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1.
Children (Basel) ; 11(3)2024 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-38539317

RESUMO

Changes in lifestyle during the pandemic may have predisposed adolescents to vulnerability to poor mental health. This study aims to evaluate these changes and their association with the course of anxiety. A prospective study was conducted with 153 participants (16 years old, 72% female) who were assessed before the pandemic (T0, November 2019-January 2020) and one year later (T1, April-May 2021). Lifestyle habits (free-time activities, maladaptive behaviors, sleep, screen use) and anxiety were measured. Data concerning experiences related to COVID-19 and family relations during lockdown were collected. A worsening in lifestyle habits and anxiety was found. Of note, the pattern of associations between lifestyle habits and anxiety was quite different in the two time-points, suggesting that the purpose and the impact of some habits may be changed after the pandemic. Regression analyses showed that increases in anxiety were associated with increases in sleep problems, heightened efforts to reduce screen time, and loneliness. Pathway analysis revealed the absence of cross-lagged effects among anxiety, screen use, and sleep, while concurrent associations between variables were found in both the assessments. These results suggest possible long-term effects of the pandemic. Risk-factors associated with the course of anxiety were identified among lifestyle habits, thus contributing to identifying targets for interventions.

2.
Artigo em Inglês | MEDLINE | ID: mdl-33941285

RESUMO

BACKGROUND: Emotion Dysregulation (ED), childhood trauma and personality are linked to the occurrence of maladaptive behaviours in adolescence which, in turn, may be related to increased risk for psychopathology in the life course. We sought to explore the relationship among the occurrence of different clusters of maladaptive behaviours and ED, clinical features (i.e. impulsivity, childhood maltreatment, anxiety, depressive symptoms) and personality traits that have been found to be associated to Borderline Personality Disorder (BPD), in a sample of 179 adolescent students. METHODS: Multiple Correspondence Analysis (MCA) was applied to detect clustered types of maladaptive behaviours and groups of students were defined as individuals engaging in these clustered behaviours (non-suicidal self-injury-NSSI, binge eating, binge drinking, cannabis use, and sexual risk behaviours). Logistic models were used to evaluate the association among clinical scales, and student groups. Mediation analysis was used to evaluate whether clinical features affected the association between personality traits and student groups. RESULTS: MCA analysis allowed to identify three student groups: NSSI/binge eating (NSSI-BE) behaviours, other maladaptive behaviours and "none". Higher scores in ED, impulsivity, childhood maltreatment, anxiety and depressive symptoms increased the risk of belonging to the cluster of NSSI-BE behaviours compared to the other two groups. ED, depression and anxiety symptoms were found to be mediators of the relationship between specific personality traits, mainly pertaining to the negative affectivity construct, and NSSI/BE. CONCLUSIONS: Individuals engaging in NSSI-BE behaviours represent a vulnerable adolescent population. ED, depression and anxiety were mediators of the relationship between a variety of personality traits related to BPD and NSSI and binge eating behaviours. Findings have important clinical implications in terms of prevention and interventions among adolescents engaging in self-damaging behaviours.

3.
EMBO J ; 39(12): e101732, 2020 06 17.
Artigo em Inglês | MEDLINE | ID: mdl-32378734

RESUMO

Innate immune signaling via TLR4 plays critical roles in pathogenesis of metabolic disorders, but the contribution of different lipid species to metabolic disorders and inflammatory diseases is less clear. GM3 ganglioside in human serum is composed of a variety of fatty acids, including long-chain (LCFA) and very-long-chain (VLCFA). Analysis of circulating levels of human serum GM3 species from patients at different stages of insulin resistance and chronic inflammation reveals that levels of VLCFA-GM3 increase significantly in metabolic disorders, while LCFA-GM3 serum levels decrease. Specific GM3 species also correlates with disease symptoms. VLCFA-GM3 levels increase in the adipose tissue of obese mice, and this is blocked in TLR4-mutant mice. In cultured monocytes, GM3 by itself has no effect on TLR4 activation; however, VLCFA-GM3 synergistically and selectively enhances TLR4 activation by LPS/HMGB1, while LCFA-GM3 and unsaturated VLCFA-GM3 suppresses TLR4 activation. GM3 interacts with the extracellular region of TLR4/MD2 complex to modulate dimerization/oligomerization. Ligand-molecular docking analysis supports that VLCFA-GM3 and LCFA-GM3 act as agonist and antagonist of TLR4 activity, respectively, by differentially binding to the hydrophobic pocket of MD2. Our findings suggest that VLCFA-GM3 is a risk factor for TLR4-mediated disease progression.


Assuntos
Gangliosídeo G(M3)/metabolismo , Monócitos/metabolismo , Obesidade/metabolismo , Transdução de Sinais , Receptor 4 Toll-Like/metabolismo , Animais , Gangliosídeo G(M3)/química , Gangliosídeo G(M3)/genética , Células HEK293 , Humanos , Camundongos , Camundongos Mutantes , Monócitos/química , Obesidade/genética , Multimerização Proteica , Receptor 4 Toll-Like/química , Receptor 4 Toll-Like/genética
4.
Fish Physiol Biochem ; 43(3): 849-862, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28097495

RESUMO

Hypoxia can affect various fish populations, including yellow perch Perca flavescens, which is an economically and ecologically important species in Lake Erie, a freshwater system that often experiences hypoxia in the hypolimnetic part of the lake. Fish, similarly to mammals, possess molecular oxygen sensor-hypoxia-inducible factor-1 (HIF-1), a transcription factor that can affect expression of many downstream genes related to animal growth and locomotion, protein synthesis, as well as ATP and amino acid metabolism. HIF-1 is a heterodimer, which consists of two subunits: oxygen-sensitive and oxygen-insensitive subunits, α and ß, respectively. In this study, we report first on the molecular cloning and sequencing of P. flavescens HIF-1α. The full-length complementary DNA (cDNA) was isolated and submitted to the GenBank with accession number KT783483. It consists of 3529 base pairs (bp) carrying a single open-reading frame that encompasses 2250 bp of the coding region, 247 bp of the 5' untranslated region (UTR), and 1032 bp of the 3' UTR. The "de novo" prediction of the 3D structure of HIF-1α protein, which consists of 749 amino acids, is presented, too. We then utilized One-Step Taqman® real-time RT-PCR technology to monitor changes in HIF-1α messenger RNA (mRNA) copies in response to chronic hypoxic stress. An experiment was conducted using 14-day post-swim-up stage yellow perch larvae with uninflated swim bladders. This experiment included three treatment groups: hypoxia, mid-hypoxia, and normoxia, in four replicates (four tanks per treatment) with the following dissolved oxygen levels: 3, 4, and >7 mg O2/L, respectively. At the end (2 weeks) and in the middle (1 week) of the experiment, fish from each tank were sampled for body measurements and molecular biology analysis. The results showed no differences in survival (∼90%) between treatment groups. Oxygen concentration was lowered to 3.02 ± 0.15 (mean ± SE) mg O2/L with no adverse effect on fish survival. The highest growth rate was observed in the normoxic group. A similar trend was observed with fish body length. The growth rate of fish declined with decreasing water-dissolved oxygen. The number of HIF-1α mRNA copies was not significantly different between hypoxic, mid-hypoxic, and normoxic conditions, and this was true for fish obtained in the middle and at the end of the experiment. Graphical abstract.


Assuntos
Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Oxigênio/farmacologia , Percas/fisiologia , Sequência de Aminoácidos , Animais , Sequência de Bases , Clonagem Molecular , DNA Complementar/genética , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , RNA/genética , RNA/metabolismo , Água/química
5.
Gynecol Oncol ; 138(2): 378-82, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26050920

RESUMO

OBJECTIVES: New treatment options for advanced and recurrent endometrial carcinoma (EC) are necessary. Epidemiological studies showed that diabetic patients using metformin have reduced risks of endometrial cancer (EC) incidence. Moreover, pre- and clinical studies demonstrated an antitumor effect by metformin, with and without additional treatments, for different solid malignancies. However, cancer cell-autonomous effects of metformin on EC have not been fully characterized yet. The aim of this study was to investigate the effect of metformin, with or without carboplatin, on patient-derived primary endometrioid EC cells xenografted in nude mice, to assess its ability to reduce or impair growth in already established tumors. METHODS: Two xenograft models were established by subcutaneous inoculation of primary endometrioid EC cell suspensions. Tumors were allowed to grow and then mice were treated with metformin (250 mg/kg, daily, p.o.), carboplatin (50 mg/kg, 1×/week, i.p.), or the combination of both compounds at the same concentration as single treatment, for three weeks. Effects of metformin treatment on the tumor mass were determined by tumor growth follow-up. Metformin influences on AMPK/mTOR cell signaling were evaluated by investigating AKT, AMPK and S6 phosphorylation levels. RESULTS: In vivo, metformin did not affect the growth of EC tumors established from patient-derived primary cultures and the phosphorylation of AKT, AMPK and S6. In addition, no enhanced antitumor effect was determined by combining metformin and carboplatin treatments. CONCLUSIONS: Metformin, at clinically relevant concentrations, did not show effects on the growth of already established tumors. Adding metformin to carboplatin did not have synergistic effects.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Carcinoma Endometrioide/tratamento farmacológico , Neoplasias do Endométrio/tratamento farmacológico , Metformina/farmacologia , Animais , Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Carboplatina/administração & dosagem , Carcinoma Endometrioide/patologia , Neoplasias do Endométrio/patologia , Feminino , Humanos , Metformina/administração & dosagem , Camundongos , Camundongos Nus , Ensaios Antitumorais Modelo de Xenoenxerto
6.
J Nutr Sci ; 4: e21, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26097704

RESUMO

The objective of the present study was to examine the effect of diets with descending fish meal (FM) inclusion levels and the addition of salt to the diet containing the lowest FM level on growth performances, feed conversion ratio, and intestinal solute carrier family 6 member 19 (SLC6A19) and oligopeptide transporter 1 (PEPT1) transcript levels, in freshwater-adapted European sea bass (Dicentrarchus labrax). We first isolated by molecular cloning and sequenced a full-length cDNA representing the neutral amino acid transporter SLC6A19 in sea bass. The cDNA sequence was deposited in GenBank database (accession no. KC812315). The twelve transmembrane domains and the 'de novo' prediction of the three-dimensional structure of SLC6A19 protein (634 amino acids) are presented. We then analysed diet-induced changes in the mRNA copies of SLC6A19 and PEPT1 genes in different portions of sea bass intestine using real-time RT-PCR. Sea bass were fed for 6 weeks on different diets, with ascending levels of fat or descending levels of FM, which was replaced with vegetable meal. The salt-enriched diet was prepared by adding 3 % NaCl to the diet containing 10 % FM. SLC6A19 mRNA in the anterior and posterior intestine of sea bass were not modulated by dietary protein sources and salt supplementation. Conversely, including salt in a diet containing a low FM percentage up-regulated the mRNA copies of PEPT1 in the hindgut. Fish growth correlated positively with the content of FM in the diets. Interestingly, the addition of salt to the diet containing 10 % FM improved feed intake, as well as specific growth rate and feed conversion ratio.

7.
Plast Surg Int ; 2014: 472604, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24987526

RESUMO

The increasing use of commercially available acellular dermis matrices for postmastectomy breast reconstruction seems to have simplified the surgical procedure and enhanced the outcome. These materials, generally considered to be highly safe or with only minor contraindications due to the necessary manipulation in preparatory phases, allow an easier one-phase surgical procedure, in comparison with autologous flaps, offering a high patient satisfaction. Unfortunately, the claim for a higher rate of complications associated with irradiation at the implant site, especially when the radiation therapy was given before the reconstructive surgery, suggested a careful behaviour when this technique is preferred. However, this hypothesis was never submitted to a crucial test, and data supporting it are often discordant or incomplete. To provide a comprehensive analysis of the field, we searched and systematically reviewed papers published after year 2005 and registered clinical trials. On the basis of a meta-analysis of data, we conclude that the negative effect of the radiotherapy on the breast reconstruction seems to be evident even in the case of acellular dermis matrices aided surgery. However, more trials are needed to make solid conclusions and clarify the poor comprehension of all the factors negatively influencing outcome.

8.
Gene ; 511(2): 326-37, 2012 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-23041082

RESUMO

Atg1 is a Serine/Threonine protein kinase that plays a pivotal role in autophagy. A complete coding sequence of ATG1 is not available for the silkworm, Bombyx mori which is a good model for studying the autophagic process. In the present study we isolated two full-length cDNAs of 2175 (transcript variant A) and 2271 (transcript variant B) bases representing ATG1 in the silkworm. Phylogenetic analysis indicated that BmATG1 was closely related to orthologs of other insects. The encoded BmAtg1 proteins shared extensive homology with orthologs from yeast to mammals, showing high conservation at the N-terminal region where the catalytic domain and ATP- and Mg-binding sites are located. A de novo prediction of the three-dimensional structure for each protein is presented. We used real-time RT-PCR to quantify dynamic changes in mRNA copy number of BmATG1 in the midgut and fat body of fifth instar larvae undergoing starvation, as well as in other tissues of silkworm at the end of last larval instar. Our qPCR results revealed that BmATG1 expression levels at the end of larval life were comparable in the midgut, fat body and Malpighian tubules, while these were higher in the gonads; moreover, the mRNA copy number of ATG1 was very different among the anterior, middle and posterior silk glands. Real-time PCR analysis also showed that starvation significantly influenced BmATG1 mRNA copy number in the fat body of silkworm, inducing an upregulation 24h after food withdrawal, with only a slight effect in the midgut. Low expression levels of BmATG1 were observed in both tissues of control animals up to the second day of spinning phase.


Assuntos
Bombyx/genética , Proteínas de Insetos/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Linhagem Celular , Clonagem Molecular , Primers do DNA , DNA Complementar , Regulação da Expressão Gênica , Humanos , Imuno-Histoquímica , Proteínas de Insetos/química , Dados de Sequência Molecular , Filogenia , Processamento de Proteína Pós-Traducional , Reação em Cadeia da Polimerase em Tempo Real , Homologia de Sequência de Aminoácidos
9.
BMC Immunol ; 12: 69, 2011 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-22204309

RESUMO

BACKGROUND: In comparison to higher vertebrates, fish are thought to rely heavily on innate immune system for initial protection against pathogen invasion because their acquired immune system displays a considerably poor immunological memory, and short-lived secondary response. The endogenous antimicrobial polypeptides (AMPPs) directly and rapidly killing pathogens such as bacteria, fungi, parasites, and viruses are included within the realm of innate defenses. In addition to piscidins, AMPPs that in recent years have been shown to be commonly linked to innate defense, are histones and their polypeptide fragments, and peptides derived from the respiratory protein hemoglobin. There is evidence that a number of stresses lead to significant regulation of AMPPs and thus their monitoring could be a highly sensitive measure of health status and risk of an infectious disease outbreak, which is a major impediment to the continued success of virtually all aquaculture enterprises and is often the most significant cause of economic losses. RESULTS: We firstly isolated and deposited in Genbank database the cDNA sequences encoding for hemoglobin-ß-like protein (Hb-LP) [GeneBank: JN410659], H2B histone-like protein 1 (HLP1) GenBank: JN410660], and HLP2 [GenBank: JN410661]. The "de novo" prediction of the three-dimensional structures for each protein is presented. Phylogenetic trees were constructed on Hb-LP, HLP1, and HLP2 sequences of sea bass and those of other teleost, avian, reptiles, amphibian and mammalian species. We then used real time RT-PCR technology to monitor for the first time in sea bass, dynamic changes in mRNA copy number of Hb-LP, HLP1, HLP2, and dicentracin in gills, skin, eyes, stomach and proximal intestine in response to acute crowding/confinement stress. We showed that acute crowding stress induces an increase in the expression levels of the aforementioned genes, in gills and skin of sea bass, but not in other tissues, and that this expression patterns are not always rapidly reversed upon re-exposure to normal conditions. CONCLUSION: The higher expression of the four target genes in gills and skin of sea bass suggests that this AMPP represents a first and immediate line of defense in combating pathogens and stressors since these tissues constitute the first physiological barriers of the animal.


Assuntos
Peptídeos Catiônicos Antimicrobianos/genética , Bass/genética , RNA Mensageiro/metabolismo , Estresse Fisiológico , Animais , Peptídeos Catiônicos Antimicrobianos/química , Bass/classificação , Sítios de Ligação , DNA Complementar/química , Evolução Molecular , Perfilação da Expressão Gênica , Modelos Moleculares , Anotação de Sequência Molecular , Dados de Sequência Molecular , Filogenia , Processamento de Proteína Pós-Traducional , Estrutura Terciária de Proteína , Análise de Sequência de DNA
10.
J Appl Toxicol ; 30(8): 730-44, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21117037

RESUMO

Nanotechnology is expected to be promising in many fields of medical applications, mainly in cancer treatment. While a large number of very attractive exploitations open up for the clinics, regulatory agencies are very careful in admitting new nanomaterials for human use because of their potential toxicity. The very active research on new nanomaterials that are potentially useful in medicine has not been counterbalanced by an adequate knowledge of their pharmacokinetics and toxicity. The different nanocarriers used to transport and release the active molecules to the target tissues should be treated as additives, with potential side effects of themselves or by virtue of their dissolution or aggregation inside the body. Only recently has a systematic classification of nanomaterials been proposed, posing the basis for dedicated modeling at the nanoscale level. The use of in silico methods, such as nano-QSAR and PSAR, while highly desirable to expedite and rationalize the following stages of toxicological research, are not an alternative, but an introduction to mandatory experimental work.


Assuntos
Portadores de Fármacos/farmacocinética , Nanomedicina/métodos , Nanoestruturas/efeitos adversos , Nanoestruturas/uso terapêutico , Humanos , Nanoestruturas/química , Medição de Risco
11.
Gene ; 450(1-2): 85-93, 2010 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-19879341

RESUMO

Brain-derived neurotrophic factor (BDNF) belongs to neurotrophin family, a class of molecules playing key roles in neuronal development, survival and regeneration, neurite growth and plasticity: memory processes are mainly affected, and mutations of the human BDNF gene are associated to cognitive and behavioural disturbances. All neurotrophins contain a highly conserved C-terminal domain and bind to the same receptor family. Both correct folding and post-translational processing of the entire preproprotein are pivotal for sorting to the extracellular space, dimerization and receptor binding. Evolutionary studies conducted so far demonstrate that a single ancestor gene underwent two independent duplication events at an early stage of vertebrate evolution, leading to the formation of the current neurotrophins. However, works focusing on BDNF evolution are scarce and fragmentary, mainly in lower vertebrates. In this work, we report cloning of eight DNA sequences from amphibians and teleosts, and analysis of the entire coding regions (cDNA sequences) of BDNF from 35 organisms, from teleosts to mammals. A phylogenetic tree was constructed and the analysis of non-synonymous-synonymous substitution rates performed for the different branches. Our results suggest that natural selection is acting on mammals, separating them from other classes. Since preproprotein cleavage and 3D structure of mature protein are important for functional activity of BDNF, we also propose a de novo prediction of the 3D structure of translates in at least one species for each class, in order to get hints about the functional constraints of the protein.


Assuntos
Fator Neurotrófico Derivado do Encéfalo/classificação , Evolução Molecular , Sequência de Aminoácidos , Anfíbios/genética , Animais , Sequência de Bases , Fator Neurotrófico Derivado do Encéfalo/genética , Gatos , Bovinos , Clonagem Molecular , Humanos , Camundongos , Dados de Sequência Molecular , Filogenia , Ratos
12.
Gene ; 410(1): 207-13, 2008 Feb 29.
Artigo em Inglês | MEDLINE | ID: mdl-18234455

RESUMO

Blue Fin Tuna (BFT), Thunnus thynnus, has been seriously endangered by global massive overfishing and by the pollution of marine environment. Feeding and fattening of caught tuna in marine cages is a recent resource, but the development of a self-sustained aquaculture activity, being independent from the supply of wild fish, is required from both industrial and conservation perspectives. At this scope, several technical problems have to be solved and the control of reproduction is the cardinal one. Beside the technological developments of farming facilities and protocols, a molecular approach seems promising for the studies of appropriate nutritional strategies, reproduction physiology and animal welfare, as well as lifestyle and response to endocrine disruptor pollutants. In this context, we have started an EST project on this species sequencing 2743, 2907, and 3014 clones from expression libraries of ovary, testis and liver, respectively, and 1499 clones from an ovary normalized library. Thanks to this project, we have identified several sequences with known function in other organisms, but not previously described in this species. Among the new genes, 712 were found only in the expression library of the ovary, 613 in that of the testis and 318 in that of the liver, while 324 additional genes were shared by two or more expression libraries; other 127 genes not found in the expression libraries were obtained from the ovary normalized library. This represents a contribution to the knowledge of the molecular basis of BFT and a necessary step for facilitating further molecular studies on this species. Accession numbers: EC 091633 to EC 093160; EG 629962 to EG 631176; EC 917676 to EC 919417; EG 999340 to EG 999999; EH 000001 to EH 000505; EH 667253 to EH 668984; EL 610526 to EL 611807; EC 42144 to EC 422414; and EH 379568 to EH 380065.


Assuntos
Perfilação da Expressão Gênica , Gônadas/metabolismo , Fígado/metabolismo , Atum/genética , Animais , Sequência de Bases , Primers do DNA , Dados de Sequência Molecular
13.
Gene Expr ; 14(2): 117-27, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-18257394

RESUMO

Perch are promising species for freshwater aquaculture and, differently from other fish, have not yet been domesticated through artificial selection; therefore, they show a wide genetic variability that is undesirable for aquaculture. In addition to the more traditional methods of aquatic biotechnology, the most recently developed molecular biological techniques can augment the overall efficiency of aquaculture. To help these new molecular techniques find their place in the everyday management of fish farming, we should make an effort to reduce the gap in genomic resources that separates farming species from "model organisms." We performed single-pass sequencing on 1237 randomly selected clones from a perch liver cDNA expression library, 350 clones of a brain-minus-liver, and 639 clones of a liver-minus-brain subtraction library. The sequences were deposited in the NCBI Expressed Sequence Tags database (www.ncbi.nlm.nih.gov/projects/dbEST). In the three libraries we identified 108, 46, and 104 genes, respectively. EST cataloguing and profiling of perch will provide a basis for functional genomic research in this species, but will also promote studies in comparative and environmental genomics, for identifying polymorphic markers that are useful, for example, to survey the disease resistance of fish and for discovering of new molecular markers of exposure. Using these genomic resources, micro- and macroarrays can be produced that will give immediate and practical benefits in the field of aquaculture, allowing early diagnosis of the fish conditions and helping in the generation of new mechanistic data on the nature of fish responses to different farming conditions.


Assuntos
Etiquetas de Sequências Expressas , Perfilação da Expressão Gênica , Animais , Peptídeos Catiônicos Antimicrobianos/genética , Sequência de Bases , Primers do DNA , DNA Complementar , Hepcidinas , Hibridização de Ácido Nucleico , Percas , RNA Mensageiro/genética
14.
Photosynth Res ; 71(1-2): 33-44, 2002.
Artigo em Inglês | MEDLINE | ID: mdl-16228499

RESUMO

Chemical oxidation of the chlorosomes from Chloroflexus aurantiacus and Chlorobium tepidum green bacteria produces bacteriochlorophyll radicals, which are characterized by an anomalously narrow EPR signal compared to in vitro monomeric BChl c (.+) [Van Noort PI, Zhu Y, LoBrutto R and Blankenship RE (1997) Biophys J 72: 316-325]. We have performed oxidant concentration and temperature-dependent X-band EPR measurements in order to elucidate the line narrowing mechanism. The linewidth decreases as the oxidant concentration is increased only for Chloroflexus indicating that for this system Heisenberg spin exchange is at least partially responsible for the EPR spectra narrowing. For both species the linewidth is decreasing on increasing the temperature. This indicates that temperature-activated electron transfer is the main narrowing mechanism for BChl radicals in chlorosomes. The extent of the electron transfer process among different BChl molecules has been evaluated and a comparison between the two species representative of the two green bacteria families has been made. In parallel, high frequency EPR experiments have been performed on the oxidized chlorosomes of Chloroflexus and Chlorobium at 110 and 330 GHz in the full temperature range investigated at X-band. The g-tensor components obtained from the simulation of the 330 GHz EPR spectrum from Chlorobium show the same anisotropy as those of monomeric Chl a (.+) [Bratt PJ, Poluektov OG, Thurnauer MC, Krzystek J, Brunel LC, Schrier J, Hsiao YW, Zerner M and Angerhofer A (2000) J Phys Chem B 104: 6973-6977]. The spectrum of Chloroflexus has a nearly axial g-tensor with reduced anisotropy compared to Chlorobium and monomeric Chl a in vitro. g-tensor values and temperature dependence of the linewidth have been discussed in terms of the differences in the local structure of the chlorosomes of the two families.

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