Fluorescent proteins and their use in marine biosciences, biotechnology, and proteomics

Designing of future ornamental crops: a biotechnological driven perspective

With a basis in human appreciation of beauty and aesthetic values, the new era of ornamental crops is based on implementing innovative technologies and transforming symbols into tangible assets. Recent advances in plant biotechnology have attracted considerable scientific and industrial interest, particularly in terms of modifying desired plant traits and developing future ornamental crops. By utilizing omics approaches, genomic data, genetic engineering, and gene editing tools, scientists have successively explored the underlying molecular mechanism and potential gene(s) behind trait regulation such as floral induction, plant architecture, stress resistance, plasticity, adaptation, and phytoremediation in ornamental crop species. These signs of progress lay a theoretical and practical foundation for designing and enhancing the efficiency of ornamental plants for a wide range of applications. In this review, we briefly summarized the existing literature and advances in biotechnological approaches for the improvement of vital traits in ornamental plants. The future ornamental plants, such as light-emitting plants, biotic/abiotic stress detectors, and pollution abatement, and the introduction of new ornamental varieties via domestication of wild species are also discussed.

Sea as a color palette: the ecology and evolution of fluorescence

Fluorescence and luminescence are widespread optical phenomena exhibited by organisms living in terrestrial and aquatic environments. While many underlying mechanistic features have been identified and characterized at the molecular and cellular levels, much less is known about the ecology and evolution of these forms of bioluminescence. In this review, we summarize recent findings in the evolutionary history and ecological functions of fluorescent proteins (FP) and pigments. Evidence for green fluorescent protein (GFP) orthologs in cephalochordates and non-GFP fluorescent proteins in vertebrates suggests unexplored evolutionary scenarios that favor multiple independent origins of fluorescence across metazoan lineages. Several context-dependent behavioral and physiological roles have been attributed to fluorescent proteins, ranging from communication and predation to UV protection. However, rigorous functional and mechanistic studies are needed to shed light on the ecological functions and control mechanisms of fluorescence.

Marine-Derived Pharmaceuticals - Challenges and Opportunities

Marine biosphere is the largest one of the earth and harbors an enormous number of different organisms. Living conditions differ fundamentally from those in terrestrial environment. The production of specific secondary metabolites is an important adaption mechanism of marine organisms to survive in the sea. These metabolites possess biological activities which make them interesting as possible drugs for human. The review presents sources, chemistry, production and pharmacology of FDA approved marine derived pharmaceuticals arranged according to their therapeutic indication. Four of the presently seven approved drugs are used for the treatment of cancer. Each another one is applicated for treatment of viral diseases, chronic pain and to lower triglyceride level in blood. Some other products are of interest in diagnostic and as experimental tools. Besides, this article describes challenges in drug development from marine sources, especially the supply problem.

The evolution of genes encoding for green fluorescent proteins: insights from cephalochordates (amphioxus)

Green Fluorescent Protein (GFP) was originally found in cnidarians, and later in copepods and cephalochordates (amphioxus) (Branchiostoma spp). Here, we looked for GFP-encoding genes in Asymmetron, an early-diverged cephalochordate lineage, and found two such genes closely related to some of the Branchiostoma GFPs. Dim fluorescence was found throughout the body in adults of Asymmetron lucayanum, and, as in Branchiostoma floridae, was especially intense in the ripe ovaries. Spectra of the fluorescence were similar between Asymmetron and Branchiostoma. Lineage-specific expansion of GFP-encoding genes in the genus Branchiostoma was observed, largely driven by tandem duplications. Despite such expansion, purifying selection has strongly shaped the evolution of GFP-encoding genes in cephalochordates, with apparent relaxation for highly duplicated clades. All cephalochordate GFP-encoding genes are quite different from those of copepods and cnidarians. Thus, the ancestral cephalochordates probably had GFP, but since GFP appears to be lacking in more early-diverged deuterostomes (echinoderms, hemichordates), it is uncertain whether the ancestral cephalochordates (i.e. the common ancestor of Asymmetron and Branchiostoma) acquired GFP by horizontal gene transfer (HGT) from copepods or cnidarians or inherited it from the common ancestor of copepods and deuterostomes, i.e. the ancestral bilaterians.

Highly sensitive and selective fluorescence detection of Hg(ii) ions based on R-phycoerythrin from Porphyra yezoensis

R-Phycoerythrin (R-PE) is a kind of natural fluorescent protein from marine Porphyra yezoensis.

Label-free colorimetric logic gates based on free gold nanoparticles and the coordination strategy between cytosine and silver ions

A colorimetric sensing strategy combined with logic gates was demonstrated by taking advantage of the dispersion and aggregation of gold nanoparticles.

Spectral and structural comparison between bright and dim green fluorescent proteins in Amphioxus

The cephalochordate Amphioxus naturally co-expresses fluorescent proteins (FPs) with different brightness, which thus offers the rare opportunity to identify FP molecular feature/s that are associated with greater/lower intensity of fluorescence. Here, we describe the spectral and structural characteristics of green FP (bfloGFPa1) with perfect (100%) quantum efficiency yielding to unprecedentedly-high brightness, and compare them to those of co-expressed bfloGFPc1 showing extremely-dim brightness due to low (0.1%) quantum efficiency. This direct comparison of structure-function relationship indicated that in the bright bfloGFPa1, a Tyrosine (Tyr159) promotes a ring flipping of a Tryptophan (Trp157) that in turn allows a cis-trans transformation of a Proline (Pro55). Consequently, the FP chromophore is pushed up, which comes with a slight tilt and increased stability. FPs are continuously engineered for improved biochemical and/or photonic properties, and this study provides new insight to the challenge of establishing a clear mechanistic understanding between chromophore structural environment and brightness level.

Fluorescence techniques in analysis of protein-ligand interactions

Fluorescence spectroscopy may serve as a universal tool for the study of protein-ligand interactions. Applications of fluorometry have made use of various aspects of fluorescence such as intensity, emission and excitation spectra, lifetime, quantum yield, polarization state, and anisotropy, as well as energy transfer and other electronic phenomena. An experimentalist has to consider each of these characteristics carefully, frequently in combination with each other, for the analysis of protein-ligand complexes and for the determination of binding constants. Most of the available techniques are of a rather general nature and a wealth of possibilities exists for their utilization. In this chapter we will provide a short survey of selected techniques that can be used for measuring binding constants and probing protein-ligand interactions. Basic principles and phenomena are discussed followed by experimental considerations and examples of binding constant determination. Emphasis is placed on steady-state techniques that employ the use of intrinsic protein fluorescence, labeled ligands, as well as anisotropy and resonance energy transfer.

What lies underneath: conserving the oceans' genetic resources

The marine realm represents 70% of the surface of the biosphere and contains a rich variety of organisms, including more than 34 of the 36 living phyla, some of which are only found in the oceans. The number of marine species used by humans is growing at unprecedented rates, including the rapid domestication of marine species for aquaculture and the discovery of natural products and genes of medical and biotechnological interest in marine biota. The rapid growth in the human appropriation of marine genetic resources (MGRs), with over 18,000 natural products and 4,900 patents associated with genes of marine organisms, with the latter growing at 12% per year, demonstrates that the use of MGRs is no longer a vision but a growing source of biotechnological and business opportunities. The diversification of the use of marine living resources by humans calls for an urgent revision of the goals and policies of marine protected areas, to include the protection of MGRs and address emerging issues like biopiracy or benefit sharing. Specific challenges are the protection of these valuable resources in international waters, where no universally accepted legal framework exists to protect and regulate the exploitation of MGRs, and the unresolved issues on patenting components of marine life. Implementing steps toward the protection of MGRs is essential to ensure their sustainable use and to support the flow of future findings of medical and biotechnological interest.

Transfection of living HeLa cells with fluorescent poly-cytosine encapsulated Ag nanoclusters

The fluorescence of silver clusters encapsulated by single stranded oligo-DNA (24 cytosine base pairs, C(24):Ag(n)) was used to monitor the transfection of this new silver/DNA fluorophore inside living HeLa cells. For this, the C(24):Ag(n) molecules were complexed with a commercially available transfection reagent Lipofectamine and the internalization of C(24):Ag(n) was followed with confocal fluorescence microscopy. Bright near-infrared fluorescence was observed from inside the transfected HeLa cells, when exciting with 633 nm excitation, opening up the possibility for the use of these C(24):Ag(n) clusters for biological labelling and imaging of living cells and for monitoring the transfection process with limited harm to the living cells.

A green fluorescent protein with photoswitchable emission from the deep sea

A colorful variety of fluorescent proteins (FPs) from marine invertebrates are utilized as genetically encoded markers for live cell imaging. The increased demand for advanced imaging techniques drives a continuous search for FPs with new and improved properties. Many useful FPs have been isolated from species adapted to sun-flooded habitats such as tropical coral reefs. It has yet remained unknown if species expressing green fluorescent protein (GFP)-like proteins also exist in the darkness of the deep sea. Using a submarine-based and -operated fluorescence detection system in the Gulf of Mexico, we discovered ceriantharians emitting bright green fluorescence in depths between 500 and 600 m and identified a GFP, named cerFP505, with bright fluorescence emission peaking at 505 nm. Spectroscopic studies showed that ∼15% of the protein bulk feature reversible ON/OFF photoswitching that can be induced by alternating irradiation with blue und near-UV light. Despite being derived from an animal adapted to essentially complete darkness and low temperatures, cerFP505 maturation in living mammalian cells at 37°C, its brightness and photostability are comparable to those of EGFP and cmFP512 from shallow water species. Therefore, our findings disclose the deep sea as a potential source of GFP-like molecular marker proteins.

Dark states in monomeric red fluorescent proteins studied by fluorescence correlation and single molecule spectroscopy

Monomeric red fluorescent proteins (mRFPs) have become indispensable tools for studying protein dynamics, interactions and functions in the cellular environment. Their emission spectrum can be well separated from other fluorescent proteins, and their monomeric structure preserves the natural function of fusion proteins. However, previous photophysical studies of some RFPs have shown the presence of light-induced dark states that can complicate the interpretation of cellular experiments. In this article, we extend these studies to mRFP1, mCherry, and mStrawberry by means of fluorescence correlation spectroscopy and prove that this light-driven intensity flickering also occurs in these proteins. Furthermore, we show that the flickering in these proteins is pH-dependent. Single molecule spectroscopy revealed reversible transitions from a bright to a dark state in several timescales, even up to seconds. Time-resolved fluorescence spectroscopy showed multiexponential decays, consistent with a "loose" conformation. We offer a structural basis for the fluorescence flickering using known crystal structures and point out that the environment of Glu-215 is critical for the pH dependence of the flickering in RFPs. We apply dual-color fluorescence correlation spectroscopy inside live cells to prove that this flickering can seriously hamper cellular measurements if the timescales of the flickering and diffusion are not well separated.