The Potential of Ginkgo biloba as a Source of Biologically Active Compounds-A Review of the Recent Literature and Patents.

Ginkgo biloba is a relict tree species showing high resistance to adverse biotic and abiotic environmental factors. Its fruits and leaves have high medicinal value due to the presence of flavonoids, terpene trilactones and phenolic compounds. However, ginkgo seeds contain toxic and allergenic alkylphenols. The publication revises the latest research results (mainly from 2018-2022) regarding the chemical composition of extracts obtained from this plant and provides information on the use of extracts or their selected ingredients in medicine and food production. A very important section of the publication is the part in which the results of the review of patents concerning the use of Ginkgo biloba and its selected ingredients in food production are presented. Despite the constantly growing number of studies on its toxicity and interactions with synthetic drugs, its health-promoting properties are the reason for the interest of scientists and motivation to create new food products.

Effect of Oyster Mushroom Addition on Improving the Sensory Properties, Nutritional Value and Increasing the Antioxidant Potential of Carp Meat Burgers.

The growing interest in functional food makes looking for new possibilities of enriching products with health-promoting ingredients necessary. One raw material with a very high potential for the food industry is the oyster mushroom (Pleurotus ostreatus), which has a strong antioxidant, antiviral, and anticancer effect. Carp meat (Cyprinus carpio) also has beneficial properties. It is rich in easily digestible protein, vitamins, minerals, and omega-3 fatty acids. This study aimed to evaluate the effect of oyster mushroom addition on the quality of carp burgers, with particular emphasis on the antioxidant effect. The scientific literature produced so far has not focused on the synergy between oyster mushrooms and carp meat. The addition of oyster mushrooms contributed to the increase in antioxidant properties and sensory attractiveness of burgers. The fat content in the finished product was reduced, and the degree of their oxidation was also reduced. The obtained results will contribute to the creation of innovative food products that meet the expectations of consumers looking for healthy food.

DEG10 contributes to mitochondrial proteostasis, root growth, and seed yield in Arabidopsis.

Maintaining mitochondrial proteome integrity is especially important under stress conditions to ensure a continued ATP supply for protection and adaptation responses in plants. Deg/HtrA proteases are important factors in the cellular protein quality control system, but little is known about their function in mitochondria. Here we analyzed the expression pattern and physiological function of Arabidopsis thaliana DEG10, which has homologs in all photosynthetic eukaryotes. Both expression of DEG10:GFP fusion proteins and immunoblotting after cell fractionation showed an unambiguous subcellular localization exclusively in mitochondria. DEG10 promoter:GUS fusion constructs showed that DEG10 is expressed in trichomes but also in the vascular tissue of roots and aboveground organs. DEG10 loss-of-function mutants were impaired in root elongation, especially at elevated temperature. Quantitative proteome analysis revealed concomitant changes in the abundance of mitochondrial respiratory chain components and assembly factors, which partially appeared to depend on altered mitochondrial retrograde signaling. Under field conditions, lack of DEG10 caused a decrease in seed production. Taken together, our findings demonstrate that DEG10 affects mitochondrial proteostasis, is required for optimal root development and seed set under challenging environmental conditions, and thus contributes to stress tolerance of plants.

Altered levels of LIL3 isoforms in Arabidopsis lead to disturbed pigment-protein assembly and chlorophyll synthesis, chlorotic phenotype and impaired photosynthetic performance.

Light-harvesting complex (LHC)-like (LIL) proteins contain two transmembrane helices of which the first bears a chlorophyll (Chl)-binding motif. They are widespread in photosynthetic organisms, but almost nothing is known about their expression and physiological functions. We show that two LIL3 paralogues (LIL3:1 and LIL3:2) in Arabidopsis thaliana are expressed in photosynthetically active tissues and their expression is differentially influenced by light stress. Localization studies demonstrate that both isoforms are associated with subcomplexes of LHC antenna of photosystem II. Transgenic plants with reduced amounts of LIL3:1 exhibited a slightly impaired growth and have reduced Chl and carotenoid contents as compared to wild-type plants. Ectopic overexpression of either paralogue led to a developmentally regulated switch to co-suppression of both LIL3 isoforms, resulting in a circular chlorosis of the leaf rosettes. Chlorotic sectors show severely diminished levels of LIL3 isoforms and other proteins, and thylakoid morphology was changed. Additionally, the levels of enzymes involved in Chl biosynthesis are altered in lil3 mutant plants. Our data support a role of LIL3 paralogues in the regulation of Chl biosynthesis under light stress and under standard growth conditions as well as in a coordinated ligation of newly synthesized and/or rescued Chl molecules to their target apoproteins.

Black Trumpet [Craterellus cornucopioides (L.) Pers.]-Bioactive Properties and Prospects for Application in Medicine and Production of Health-Promoting Food.

Black trumpet (Craterellus cornucopioides) is a mushroom present in many countries but underestimated. The aim of this publication is to present the latest state of knowledge about the chemical composition and bioactivity of C. cornucopioides and the possibility of its application in food. According to researchers, black trumpet is very rich in nutritional compounds, including unsaturated fatty acids (mainly oleic and linoleic acids), ß-glucans, minerals, and vitamins as well as polyphenols and tannins. It also contains compounds influencing the sensory properties, like free amino acids and nucleotides as well as sugars and polyols, mainly mannitol. Many of the described components show high nutritional and bioactive properties. Therefore, C. cornucopioides shows antioxidant activity and immunostimulating, anti-inflammatory, and anticancer effects as well as antibacterial, antifungal, antiviral, and antihyperglycemic effects. This makes black trumpet, also called horn of plenty, a mushroom with great potential for use both in medicine and directly in food. So far, black trumpet is not widely used in food, especially processed food. There are only a few studies on the use of dried black trumpet in sausages, but there is great potential for its use in food.

A novel type of light-harvesting antenna protein of red algal origin in algae with secondary plastids.

BACKGROUND: Light, the driving force of photosynthesis, can be harmful when present in excess; therefore, any light harvesting system requires photoprotection. Members of the extended light-harvesting complex (LHC) protein superfamily are involved in light harvesting as well as in photoprotection and are found in the red and green plant lineages, with a complex distribution pattern of subfamilies in the different algal lineages. RESULTS: Here, we demonstrate that the recently discovered "red lineage chlorophyll a/b-binding-like proteins" (RedCAPs) form a monophyletic family within this protein superfamily. The occurrence of RedCAPs was found to be restricted to the red algal lineage, including red algae (with primary plastids) as well as cryptophytes, haptophytes and heterokontophytes (with secondary plastids of red algal origin). Expression of a full-length RedCAP:GFP fusion construct in the diatom Phaeodactylum tricornutum confirmed the predicted plastid localisation of RedCAPs. Furthermore, we observed that similarly to the fucoxanthin chlorophyll a/c-binding light-harvesting antenna proteins also RedCAP transcripts in diatoms were regulated in a diurnal way at standard light conditions and strongly repressed at high light intensities. CONCLUSIONS: The absence of RedCAPs from the green lineage implies that RedCAPs evolved in the red lineage after separation from the the green lineage. During the evolution of secondary plastids, RedCAP genes therefore must have been transferred from the nucleus of the endocytobiotic alga to the nucleus of the host cell, a process that involved complementation with pre-sequences allowing import of the gene product into the secondary plastid bound by four membranes. Based on light-dependent transcription and on localisation data, we propose that RedCAPs might participate in the light (intensity and quality)-dependent structural or functional reorganisation of the light-harvesting antennae of the photosystems upon dark to light shifts as regularly experienced by diatoms in nature. Remarkably, in plastids of the red lineage as well as in green lineage plastids, the phycobilisome based cyanobacterial light harvesting system has been replaced by light harvesting systems that are based on members of the extended LHC protein superfamily, either for one of the photosystems (PS I of red algae) or for both (diatoms). In their proposed function, the RedCAP protein family may thus have played a role in the evolutionary structural remodelling of light-harvesting antennae in the red lineage.

The Possibility of Using Sulphur Shelf Fungus (Laetiporus sulphureus) in the Food Industry and in Medicine-A Review.

Sulphur shelf fungus (Laetiporus sulphureus) has so far been largely underestimated as a potential raw material for the food industry. Many studies have demonstrated that the extracts obtained from this mushroom and some of their components have positive effects on human health. They have antioxidant, antibacterial, and anticancer properties and regulate human metabolism and digestive processes. Water extracts also have this effect. In addition, the substances contained in this mushroom have the ability to preserve food by inhibiting the growth of undesirable microorganisms. These properties have led to the situation that in some countries, shelf sulphur fungus is legally recognized as a raw material that meets the requirements of the food and processing industries. This paper is a review of the latest information (mainly for the period 2016-2023) on the chemical composition and the possibility of using L. sulphureus in the food industry and in medicine.

Effect of Brewing Conditions on Antioxidant Properties of Ginkgo biloba Leaves Infusion.

Due to the growing awareness of the importance of healthy eating in society, there is an increasing interest in the use of herbs and low-processed, natural products. Ginkgo biloba is a raw material with a high pro-health potential, which is related to the high content of antioxidant compounds. The aim of the study was to determine the relationship between the antioxidant activity of Ginkgo biloba leaf infusions and the weighted amount of leaves and brewing time. In addition, a sensory analysis of the infusions obtained was carried out. The innovation is to determine the migration of micro- and macroelements to the infusion prepared from Ginkgo biloba depending on the leaves' weight used and the brewing time. The research showed the dependence of the antioxidant activity of the infusions and the migration of microelements on the size of the dried material and the brewing time. In the publication, the main factors influencing the quality of infusions were analysed, their mutual correlations were determined, and combinations showing the highest antioxidant activity and, at the same time, the highest sensory acceptability were selected.

The family of Deg/HtrA proteases in plants.

BACKGROUND: The Deg/HtrA family of ATP-independent serine endopeptidases is present in nearly all organisms from bacteria to human and vascular plants. In recent years, multiple deg/htrA protease genes were identified in various plant genomes. During genome annotations most proteases were named according to the order of discovery, hence the same names were sometimes given to different types of Deg/HtrA enzymes in different plant species. This can easily lead to false inference of individual protease functions based solely on a shared name. Therefore, the existing names and classification of these proteolytic enzymes does not meet our current needs and a phylogeny-based standardized nomenclature is required. RESULTS: Using phylogenetic and domain arrangement analysis, we improved the nomenclature of the Deg/HtrA protease family, standardized protease names based on their well-established nomenclature in Arabidopsis thaliana, and clarified the evolutionary relationship between orthologous enzymes from various photosynthetic organisms across several divergent systematic groups, including dicots, a monocot, a moss and a green alga. Furthermore, we identified a "core set" of eight proteases shared by all organisms examined here that might provide all the proteolytic potential of Deg/HtrA proteases necessary for a hypothetical plant cell. CONCLUSIONS: In our proposed nomenclature, the evolutionarily closest orthologs have the same protease name, simplifying scientific communication when comparing different plant species and allowing for more reliable inference of protease functions. Further, we proposed that the high number of Deg/HtrA proteases in plants is mainly due to gene duplications unique to the respective organism.

Deg proteases and their role in protein quality control and processing in different subcellular compartments of the plant cell.

Degradation of periplasmic proteins (Deg)/high temperature requirement A (HtrA) proteases are ATP-independent serine endopeptidases found in almost every organism. Database searches revealed that 16 Deg paralogues are encoded by the genome of Arabidopsis thaliana, six of which were experimentally shown to be located in chloroplasts, one in peroxisomes, one in mitochondria and one in the nucleus. Two more Deg proteases are predicted to reside in chloroplasts, five in mitochondria (one of them with a dual chloroplastidial/mitochondrial localization) and the subcellular location of one protein is uncertain. This review summarizes the current knowledge on the role of Deg proteases in maintaining protein homeostasis and protein processing in various subcompartments of the plant cell. The chloroplast Deg proteases are the best examined so far, especially with respect to their role in the degradation of photodamaged photosynthetic proteins and in biogenesis of photosystem II (PSII). A combined action of thylakoid lumen and stroma Deg proteases in the primary cleavage of photodamaged D1 protein from PSII reaction centre is discussed on the basis of a recently resolved crystal structure of plant Deg1. The peroxisomal Deg protease is a processing enzyme responsible for the cleavage of N-terminal peroxisomal targeting signals (PTSs). A. thaliana mutants lacking this enzyme show reduced peroxisomal ß-oxidation, indicating for the first time the impact of protein processing on peroxisomal functions in plants. Much less data is available for mitochondrial and nuclear Deg proteases. Based on the available expression data we hypothesize a role in general protein quality control and during acquired heat resistance.

Pineal arylalkylamine N-acetyltransferase (Aanat) gene expression as a target of inflammatory mediators in the chicken.

Previously, we demonstrated that experimental peritonitis in chickens was attenuated by treatment with exogenous melatonin, while the developing inflammation decreased pineal AANAT activity. This suggested the existence of a bidirectional relationship between the activated immune system and pineal gland function. The aim of the present study was to identify the step(s) in the chicken pineal melatonin biosynthetic pathway that are affected by inflammation. Peritonitis was evoked by i.p. injection of thioglycollate solution, either 2h after the start, or 2h before the end of the light period, and the animals were sacrificed 4h later. The effect of inflammation on the expression of genes encoding enzymes participating in melatonin biosynthesis in the pineal gland, i.e. tryptophan hydroxylase 1 (Tph1), dopa decarboxylase (Ddc), arylalkylamine N-acetyltransferase (Aanat) and acetylserotonin O-methyltransferase (Asmt), was evaluated by qPCR. The pineal and serum melatonin concentration as well as the content of its precursors in the pineal gland were measured, along with the activity of the relevant biosynthetic enzymes. Developing peritonitis caused an increase in the pineal levels of the Tph1 mRNA during the night and the Asmt mRNA during the day, while nocturnal Aanat transcription was reduced. Both the pineal and serum melatonin level and the pineal content of N-acetylserotonin (NAS) were decreased during the night in birds with peritonitis. The amount and activity of pineal AANAT were significantly reduced, while the activity of HIOMT was increased under these experimental conditions. These results indicate that the observed decrease in MEL biosynthesis in chickens with developing inflammation is a result of transcriptional downregulation of the Aanat gene, followed by reduced synthesis and activity of the encoded enzyme.

A new principle of oligomerization of plant DEG7 protease based on interactions of degenerated protease domains.

Deg/HtrA proteases are a large group of ATP-independent serine endoproteases found in almost every organism. Their usual domain arrangement comprises a trypsin-type protease domain and one or more PDZ domains. All Deg/HtrA proteases form homo-oligomers with trimers as the basic unit, where the active protease domain mediates the interaction between individual monomers. Among the members of the Deg/HtrA protease family, the plant protease DEG7 is unique since it contains two protease domains (one active and one degenerated) and four PDZ domains. In the present study, we investigated the oligomerization behaviour of this unusual protease using yeast two-hybrid analysis in vivo and with recombinant protein in vitro. We show that DEG7 forms trimeric complexes, but in contrast with other known Deg/HtrA proteases, it shows a new principle of oligomerization, where trimerization is based on the interactions between degenerated protease domains. We propose that, during evolution, a duplicated active protease domain degenerated and specialized in protein-protein interaction and complex formation.

Recombinant Deg/HtrA proteases from Synechocystis sp. PCC 6803 differ in substrate specificity, biochemical characteristics and mechanism.

Cyanobacteria require efficient protein-quality-control mechanisms to survive under dynamic, often stressful, environmental conditions. It was reported that three serine proteases, HtrA (high temperature requirement A), HhoA (HtrA homologue A) and HhoB (HtrA homologue B), are important for survival of Synechocystis sp. PCC 6803 under high light and temperature stresses and might have redundant physiological functions. In the present paper, we show that all three proteases can degrade unfolded model substrates, but differ with respect to cleavage sites, temperature and pH optima. For recombinant HhoA, and to a lesser extent for HtrA, we observed an interesting shift in the pH optimum from slightly acidic to alkaline in the presence of Mg2+ and Ca2+ ions. All three proteases formed different homo-oligomeric complexes with and without substrate, implying mechanistic differences in comparison with each other and with the well-studied Escherichia coli orthologues DegP (degradation of periplasmic proteins P) and DegS. Deletion of the PDZ domain decreased, but did not abolish, the proteolytic activity of all three proteases, and prevented substrate-induced formation of complexes higher than trimers by HtrA and HhoA. In summary, biochemical characterization of HtrA, HhoA and HhoB lays the foundation for a better understanding of their overlapping, but not completely redundant, stress-resistance functions in Synechocystis sp. PCC 6803.

Possibilities of Using Macrolepiota procera in the Production of Prohealth Food and in Medicine.

Parasol mushroom (Macrolepiota procera) is a fungus that is often included in the menu of people looking for replacements for meat products and at the same time appreciating mushrooms. Its fruiting bodies are known for their delicate flavor and aroma. The aim of the publication was to analyze the latest information (mainly from 2015 to 2021) on the chemical composition of the M. procera fruiting bodies and their antioxidant properties. The data on other health-promoting properties and the possibilities of using these mushrooms in medicine were also compiled and summarized, taking into account their antibacterial, antioxidant, anti-inflammatory, regulatory, antidepressant, and anticancer effects. Moreover, the influence of various forms of processing and conservation of raw mushroom on its health-promoting properties was discussed. The possibilities of controlling the quality of both the raw material and the prepared dishes were also discussed. Such an opportunity is offered by the possibility of modifying the growing conditions, in particular, the appropriate selection of the substrate for mushroom cultivation and the deliberate enrichment of its composition with the selected substances, which will then be incorporated into the fungus organism.

Phosphorylation and nitration levels of photosynthetic proteins are conversely regulated by light stress.

Using a label-free mass spectrometric approach, we investigated light-induced changes in the distribution of phosphorylated and nitrated proteins within subpopulations of native photosynthetic complexes in the thylakoid membrane of Arabidopsis thaliana leaves adapted to growth light (GL) and subsequently exposed to high light (HL). Eight protein phosphorylation sites were identified in photosystem II (PSII) and the phosphorylation level of seven was regulated by HL as determined based on peak areas from ion chromatograms of phosphorylated and non-phosphorylated peptides. Although the phosphorylation of PSII proteins was reported in the past, we demonstrated for the first time that two minor antenna LHCB4 isoforms are alternately phosphorylated under GL and HL conditions in PSII monomers, dimers and supercomplexes. A role of LHCB4 phosphorylation in state transition and monomerization of PSII under HL conditions is proposed. We determined changes in the nitration level of 23 tyrosine residues in five photosystem I (PSI) and nine PSII proteins and demonstrated for the majority of them a lower nitration level in PSI and PSII complexes and supercomplexes under HL conditions, as compared to GL. In contrast, the nitration level significantly increased in assembled/disassembled PSI and PSII subcomplexes under HL conditions. A possible role of nitration in (1) monomerization of LHCB1-3 trimers under HL conditions (2) binding properties of ferredoxin-NADP+ oxidoreductase to photosystem I, and (3) PSII photodamage and repair cycle, is discussed. Based on these data, we propose that the conversely regulated phosphorylation and nitration levels regulate the stability and turnover of photosynthetic complexes under HL conditions.

Mass spectrometric characterization of photooxidative protein modifications in Arabidopsis thaliana thylakoid membranes.

Oxidative and nitrosative stress leaves footprints in the plant chloroplast in the form of oxidatively modified proteins. Using a mass spectrometric approach, we identified 126 tyrosine and 12 tryptophan nitration sites in 164 nitrated proteolytic peptides, mainly from photosystem I (PSI), photosystem II (PSII), cytochrome b(6) /f and ATP-synthase complexes and 140 oxidation products of tyrosine, tryptophan, proline, phenylalanine and histidine residues. While a high number of nitration sites were found in proteins from four photosynthetic complexes indicating that the nitration belongs to one of the prominent posttranslational protein modifications in photosynthetic apparatus, amino acid oxidation products were determined mostly in PSII and to a lower extent in PSI. Exposure of plants to light stress resulted in an increased level of tyrosine and tryptophan nitration and tryptophan oxidation in proteins of PSII reaction center and the oxygen-evolving complex, as compared to low light conditions. In contrast, the level of nitration and oxidation of these amino acid residues strongly decreased for all light-harvesting proteins of PSII under the same conditions. Based on these data, we propose that oxidative modifications of proteins by reactive oxygen and nitrogen species might represent an important regulatory mechanism of protein turnover under light stress conditions, especially for PSII and its antenna proteins.

24 hour patterning in gene expression of pineal neurosteroid biosynthesis in young chickens (Gallus gallus domesticus L.).

The pineal gland, one of the three equivalent avian biological clock structures, is also the site of intensive neurosteroid synthesis (7α-hydroxypregnenolone and allopregnanolone). Pineal neurosteroid biosynthesis involves six enzymes: cytochrome P450 side-chain cleavage - Cyp11a1 encoded, cytochrome P4507α - Cyp7b1, 3ß-hydroxysteroid dehydrogenase - Hsd3b2, 5α-reductase - Srd5a1, 3α-hydroxysteroid dehydrogenase - Akr1d1, and 5ß-reductase - Srd5a3. Regulation of neurosteroid biosynthesis is not fully understood; although it is known that the E4BP4 transcription factor induces activation of biosynthetic cholesterol genes, which are the targets for SREBP (element-binding protein transcription factor). SREBP principal activity in the pineal gland is suppression and inhibition of the Period2 canonical clock gene, suggesting our hypothesis that genes encoding enzymes involved in neurosteroidogenesis are under circadian clock control and are the Clock Control Genes (CCGs). Therefore, through investigation of daily changes in Cyp11a1, Cyp7b1, Hsd3b2, Akr1d1, Srd5a1, and Srd5a3, pineal genes were tested in vivo and in vitro, in cultured pinealocytes. Experiments were carried out on pineal glands taken from 16-day-old chickens in vivo or using in vitro cultures of pinealocytes collected from 16-day-old animals. Both the birds in the in vivo experiments and the pinealocytes were kept under controlled light conditions (LD 12:12) or in constant darkness (DD). Subsequently, materials were prepared for RT-qPCR analysis. Results revealed that three of the six tested genes: Cyp11a1, Cyp7b1, and Srd5a3 demonstrated significant 24-hour variation in in vivo and in vitro. Findings of this study confirm that these genes could be under clock control and satisfy many of the requirements to be identified as CCGs.

An empirical study of affective and cognitive functions in Compulsive Sexual Behavior Disorder.

BACKGROUND AND AIMS: Despite the inclusion of the Compulsive Sexual Behavior Disorder (CSBD) in the International Classification of Diseases, very little is known about the underlying affective and cognitive processes. To fill this gap, we compared CSBD subjects and Healthy-Controls (HC) across negative/positive valence, cognitive and sensorimotor systems, as proposed by the Research Domain Criteria framework. METHODS: 74 heterosexual CSBD and 66 matched HC males were studied with 10 questionnaires and 8 behavioral tasks. Analyses were conducted with frequent and Bayesian statistics. RESULTS: CSBD individuals showed significantly higher (than HC) punishment sensitivity, anxiety, depression, compulsivity, and impulsivity symptoms. Frequentist statistical analysis revealed significant interaction between subject group and condition in Incentive Delay Task, concerning the strength of motivation and hedonic value of erotic rewards. Bayesian analysis produced evidence for the absence of group differences in Facial Discrimination Task, Risk-Ambiguity Task, and Learning Task. Also, Bayesian methods provided evidence for group differences in the Emotional Stroop Task and the Incentive Delay Task. Sexual Discounting Task, Attentional Network Task, and Stop Signal Task produced mixed results. CONCLUSIONS: Higher punishment sensitivity and impulsivity among CSBD subjects, along with significant interaction between these groups and erotic vs. non-erotic reward processing is in line with previous findings on negative/positive valence alterations in CSBD patients. This result shows that there are similarities to substance and behavioral addictions. The absence of group differences and mixed results related to cognitive and sensorimotor systems raise concerns to what extent CSBD resembles a wide spectrum of impairments observed in disorders, and demand further research.

Taxonomic distribution and origins of the extended LHC (light-harvesting complex) antenna protein superfamily.

BACKGROUND: The extended light-harvesting complex (LHC) protein superfamily is a centerpiece of eukaryotic photosynthesis, comprising the LHC family and several families involved in photoprotection, like the LHC-like and the photosystem II subunit S (PSBS). The evolution of this complex superfamily has long remained elusive, partially due to previously missing families. RESULTS: In this study we present a meticulous search for LHC-like sequences in public genome and expressed sequence tag databases covering twelve representative photosynthetic eukaryotes from the three primary lineages of plants (Plantae): glaucophytes, red algae and green plants (Viridiplantae). By introducing a coherent classification of the different protein families based on both, hidden Markov model analyses and structural predictions, numerous new LHC-like sequences were identified and several new families were described, including the red lineage chlorophyll a/b-binding-like protein (RedCAP) family from red algae and diatoms. The test of alternative topologies of sequences of the highly conserved chlorophyll-binding core structure of LHC and PSBS proteins significantly supports the independent origins of LHC and PSBS families via two unrelated internal gene duplication events. This result was confirmed by the application of cluster likelihood mapping. CONCLUSIONS: The independent evolution of LHC and PSBS families is supported by strong phylogenetic evidence. In addition, a possible origin of LHC and PSBS families from different homologous members of the stress-enhanced protein subfamily, a diverse and anciently paralogous group of two-helix proteins, seems likely. The new hypothesis for the evolution of the extended LHC protein superfamily proposed here is in agreement with the character evolution analysis that incorporates the distribution of families and subfamilies across taxonomic lineages. Intriguingly, stress-enhanced proteins, which are universally found in the genomes of green plants, red algae, glaucophytes and in diatoms with complex plastids, could represent an important and previously missing link in the evolution of the extended LHC protein superfamily.

Acclimation of Trichodesmium erythraeum ISM101 to high and low irradiance analysed on the physiological, biophysical and biochemical level.

As the nonheterocystous diazotrophic cyanobacterium Trichodesmium lives both at the ocean surface and deep in the water column, it has to acclimate to vastly different irradiances. Here, we investigate its strategy of light acclimation in several ways. In this study, we used spectrally resolved fluorescence kinetic microscopy to investigate the biophysics of photosynthesis in individual cells, analysed cell extracts for pigment and phycobiliprotein composition, measured nitrogenase activity and the abundance of key proteins, and assayed protein synthesis/degradation by radioactive labelling. After acclimation to high light, Trichodesmium grew faster at 1000 micromol m(-2) s(-1) than at 100 micromol m(-2) s(-1). This acclimation was associated with decreasing cell diameter, faster protein turnover, the down-regulation of light-harvesting pigments and the outer part of the phycobiliprotein antenna, the up-regulation of light-protective carotenoids, changes in the coupling of phycobilisomes to the reaction centres and in the coupling of individual phycobiliproteins to the phycobilisomes. The latter was particularly interesting, as it represents an as yet unreported light acclimation strategy. Only in the low light-acclimated culture and only after the onset of actinic light did phycourobilin and phycoerythrin contribute to photochemical fluorescence quenching, showing that these phycobiliproteins may become quickly (in seconds) very closely coupled to photosystem II. This fast reversible coupling also became visible in the nonphotochemical changes of the fluorescence quantum yield.