Marine pharmacology in 2001--2002: marine compounds with anthelmintic, antibacterial, anticoagulant, antidiabetic, antifungal, anti-inflammatory, antimalarial, antiplatelet, antiprotozoal, antituberculosis, and antiviral activities; affecting the cardiovascular, immune and nervous systems and other miscellaneous mechanisms of action

During 2001--2002, research on the pharmacology of marine chemicals continued to be global in nature involving investigators from Argentina, Australia, Brazil, Canada, China, Denmark, France, Germany, India, Indonesia, Israel, Italy, Japan, Mexico, Netherlands, New Zealand, Pakistan, the Philippines, Russia, Singapore, Slovenia, South Africa, South Korea, Spain, Sweden, Switzerland, Thailand, United Kingdom, and the United States. This current article, a sequel to the authors' 1998, 1999 and 2000 marine pharmacology reviews, classifies 106 marine chemicals derived from a diverse group of marine animals, algae, fungi and bacteria, on the basis of peer-reviewed preclinical pharmacology. Anthelmintic, antibacterial, anticoagulant, antifungal, antimalarial, antiplatelet, antiprotozoal, antituberculosis or antiviral activities were reported for 56 marine chemicals. An additional 19 marine compounds were shown to have significant effects on the cardiovascular, immune and nervous system as well as to possess anti-inflammatory and antidiabetic effects. Finally, 31 marine compounds were reported to act on a variety of molecular targets and thus may potentially contribute to several pharmacological classes. Thus, during 2001--2002 pharmacological research with marine chemicals continued to contribute potentially novel chemical leads for the ongoing global search for therapeutic agents for the treatment of multiple disease categories.     

Marine pharmacology in 1999: compounds with antibacterial,anticoagulant, antifungal,anthelmintic, anti-inflammatory,antiplatelet, antiprotozoal and antiviral activities affecting the cardiovascular,endocrine, immune and nervous systems,and other miscellaneous mechanisms of action

This review, a sequel to the 1998 review, classifies 63 peer-reviewed articles on the basis of the reported preclinical pharmacological properties of marine chemicals derived from a diverse group of marine animals, algae, fungi and bacteria. In all, 21 marine chemicals demonstrated anthelmintic, antibacterial, anticoagulant, antifungal, antimalarial, antiplatelet, antituberculosis or antiviral activities. An additional 23 compounds had significant effects on the cardiovascular, sympathomimetic or the nervous system, as well as possessed anti-inflammatory, immunosuppressant or fibrinolytic effects. Finally, 22 marine compounds were reported to act on a variety of molecular targets, and thus could potentially contribute to several pharmacological classes. Thus, during 1999 pharmacological research with marine chemicals continued to contribute potentially novel chemical leads in the ongoing global search for therapeutic agents for the treatment of multiple disease categories.     

Marine pharmacology in 2003-4: marine compounds with anthelmintic antibacterial, anticoagulant, antifungal, anti-inflammatory, antimalarial, antiplatelet, antiprotozoal, antituberculosis, and antiviral activities; affecting the cardiovascular, immune and nervous systems, and other miscellaneous mechanisms of action

The current marine pharmacology review that covers the peer-reviewed literature during 2003 and 2004 is a sequel to the authors' 1998-2002 reviews, and highlights the preclinical pharmacology of 166 marine chemicals derived from a diverse group of marine animals, algae, fungi and bacteria. Anthelmintic, antibacterial, anticoagulant, antifungal, antimalarial, antiplatelet, antiprotozoal, antituberculosis or antiviral activities were reported for 67 marine chemicals. Additionally 45 marine compounds were shown to have significant effects on the cardiovascular, immune and nervous system as well as possessing anti-inflammatory effects. Finally, 54 marine compounds were reported to act on a variety of molecular targets and thus may potentially contribute to several pharmacological classes. Thus, during 2003-2004, research on the pharmacology of marine natural products which involved investigators from Argentina, Australia, Brazil, Belgium, Canada, China, France, Germany, India, Indonesia, Israel, Italy, Japan, Mexico, Morocco, the Netherlands, New Zealand, Norway, Panama, the Philippines, Portugal, Russia, Slovenia, South Korea, Spain, Thailand, Turkey, United Kingdom, and the United States, contributed numerous chemical leads for the continued global search for novel therapeutic agents with broad spectrum activity.     

Marine pharmacology in 2005–6: Marine compounds with anthelmintic,antibacterial, anticoagulant,antifungal, anti-inflammatory,antimalarial, antiprotozoal,antituberculosis, and antiviral activities; affecting the cardiovascular,immune and nervous systems,and other miscellaneous mechanisms of action

Background

The review presents the 2005–2006 peer-reviewed marine pharmacology literature, and follows a similar format to the authors' 1998–2004 reviews. The preclinical pharmacology of chemically characterized marine compounds isolated from marine animals, algae, fungi and bacteria is systematically presented.

Results

Anthelmintic, antibacterial, anticoagulant, antifungal, antimalarial, antiprotozoal, antituberculosis and antiviral activities were reported for 78 marine chemicals. Additionally 47 marine compounds were reported to affect the cardiovascular, immune and nervous system as well as possess anti-inflammatory effects. Finally, 58 marine compounds were shown to bind to a variety of molecular targets, and thus could potentially contribute to several pharmacological classes.

Conclusions

Marine pharmacology research during 2005–2006 was truly global in nature, involving investigators from 32 countries, and the United States, and contributed 183 marine chemical leads to the research pipeline aimed at the discovery of novel therapeutic agents.

General significance

Continued preclinical and clinical research with marine natural products demonstrating a broad spectrum of pharmacological activity will probably result in novel therapeutic agents for the treatment of multiple disease categories.     

Marine pharmacology in 2007–8: Marine compounds with antibacterial,anticoagulant, antifungal,anti-inflammatory,antimalarial, antiprotozoal,antituberculosis, and antiviral activities; affecting the immune and nervous system,and other miscellaneous mechanisms of action

The peer-reviewed marine pharmacology literature in 2007–8 is covered in this review, which follows a similar format to the previous 1998–2006 reviews of this series. The preclinical pharmacology of structurally characterized marine compounds isolated from marine animals, algae, fungi and bacteria is discussed in a comprehensive manner. Antibacterial, anticoagulant, antifungal, antimalarial, antiprotozoal, antituberculosis and antiviral activities were reported for 74 marine natural products. Additionally, 59 marine compounds were reported to affect the cardiovascular, immune and nervous systems as well as to possess anti-inflammatory effects. Finally, 65 marine metabolites were shown to bind to a variety of receptors and miscellaneous molecular targets, and thus upon further completion of mechanism of action studies, will contribute to several pharmacological classes. Marine pharmacology research during 2007–8 remained a global enterprise, with researchers from 26 countries, and the United States, contributing to the preclinical pharmacology of 197 marine compounds which are part of the preclinical marine pharmaceuticals pipeline. Sustained preclinical research with marine natural products demonstrating novel pharmacological activities, will probably result in the expansion of the current marine pharmaceutical clinical pipeline, which currently consists of 13 marine natural products, analogs or derivatives targeting a limited number of disease categories.     

An Assessment of Toxic Substances Pollution in the Hong Kong Marine Environment

The Environmental Protection Department (EPD) of the Hong Kong Special Administrative Region Government (HKSARG) commissioned a consultancy study in 1999 to better understand the potential sources, fates, and existing pollution state of toxic substances in Hong Kong's marine environment. A desk-top survey and assessment was first performed on a comprehensive initial list of 556 toxic substances. A Preliminary Priority Toxic Substances List (PPTSL) of 135 chemicals was established, consisting of heavy metals, inorganic compounds, organo-metallic compounds, and trace organics. A territory-wide baseline field sampling and laboratory analysis exercise was then undertaken during 2001–2002 to determine the level of these PPTSL chemicals in the potential pollution sources (effluent discharges, stormwater discharges, air deposition) and the receiving marine environment (water, sediment, biota). A draft Priority Toxic Substances List (PTSL) was developed, taking into account chemicals detected in the local marine environment and those listed under the Stockholm Convention, the Rotterdam Convention, and the International Maritime Organization's Harmful Antifouling System Convention. The draft PTSL chemicals were subject to ecological and incremental human health risk assessments. Based on the risk assessment results, 17 Chemicals of Potential Concern (COPC) for Hong Kong's marine environment were identified, most of which were heavy metals in the sediment. The study findings suggest that Hong Kong's marine environment is not widely polluted with chemicals present at concentrations of toxicological concern. Although a number of potentially problematic pollutants (COPC) were identified, they are confined to a few “hot spots” and are unlikely to pose a territory-wide risk. Based on the study recommendations, the EPD initiated in 2004 a toxic substances monitoring program to keep the COPC in the marine environment under close surveillance.     

Southern Sea Otter as a Sentinel of Marine Ecosystem Health

The southern sea otter (Enhydra lutris nereis) is listed as threatened under the Endangered Species Act (ESA) and is a keystone species, strongly influencing the abundance and diversity of the other species within its kelp forest ecosystem. This is accomplished primarily by preying upon urchins that eat the kelp stipe and holdfast, which can reduce a kelp forest to an urchin barren. Sea otters are very susceptible to marine pollutants such as petroleum, which may be directly toxic and/or alter their furs insulating properties. Sea otters are an excellent sentinel species. They eat approximately 25% of their body weight per day in shellfish and other invertebrates, and can concentrate and integrate chemical contaminants. In addition, they appear to be susceptible to a number of diseases and parasites that may have anthropogenic origins, and shellfish may serve as an intermediary for some of these infections. Many of the shellfish the otters eat are also harvested for human food. In their role as sentinels, sea otter health has implications for human health, economic sustainability of shellfisheries, as well as overall marine ecosystem health. The recent southern sea otter decline has been viewed with some alarm by conservationists and, indeed, recovery seems a long way off. High mortality rather than depressed recruitment appears to underlie the decline. A good deal of debate has centered on the role of infectious diseases and parasites, exposure to contaminants, nutrition and prey availability, net and pot fishery interactions, and other sources of mortality. Current research is being done related to major classes of mortality, various types of pollutants and some specific organisms causing southern sea otter mortality, and their implications for marine ecosystem health and sustainability.     

Surface Colonization by Marine Roseobacters: Integrating Genotype and Phenotype

The Roseobacter clade is a broadly distributed, abundant, and biogeochemically relevant group of marine bacteria. Representatives are often associated with organic surfaces in disparate marine environments, suggesting that a sessile lifestyle is central to the ecology of lineage members. The importance of surface association and colonization has been demonstrated recently for select strains, and it has been hypothesized that production of antimicrobial agents, cell density-dependent regulatory mechanisms, and morphological features contribute to the colonization success of roseobacters. Drawing on these studies, insight into a broad representation of strains is facilitated by the availability of a substantial collection of genome sequences that provides a holistic view of these features among clade members. These genome data often corroborate phenotypic data but also reveal significant variation in terms of gene content and synteny among group members, even among closely related strains (congeners and conspecifics). Thus, while detailed studies of representative strains are serving as models for how roseobacters transition between planktonic and sessile lifestyles, it is becoming clear that additional studies are needed if we are to have a more comprehensive view of how these transitions occur in different lineage members. This is important if we are to understand how associations with surfaces influence metabolic activities contributing to the cycling of carbon and nutrients in the world''s oceans.The Roseobacter lineage is an abundant marine bacterial group whose members mediate key biogeochemical processes and have been the subject of several recent reviews (e.g., references 7, 11, and 91). While roseobacters are broadly distributed across diverse marine environments, roseobacter abundance is often highest near phytoplankton blooms or macroalgae, or in association with organic particles, suggesting that cell-surface interactions are a defining feature of lineage members. This is supported by culture-independent studies identifying roseobacters as ubiquitous and rapid colonizers of a variety of inorganic and organic marine surfaces, including marine algae and dinoflagellates (19, 20, 51). Though little is known of the exact mechanism(s) that roseobacters employ to physically associate with eukaryotic cell surfaces or particles, several cultivated strains have been shown to be capable of surface colonization (8, 71). Furthermore, laboratory-based studies confirm expression of traits expected to be important in colonization success, including possession of holdfast structures, motility, and chemotaxis, as well as production of quorum sensing (QS) molecules and antimicrobial metabolites in select strains. Despite the recognized importance of roseobacters in natural systems and the numerous (∼40) genome sequences that are, or are to soon be, publicly available (7), laboratory investigations of phenotypes expected to contribute to the ecological success of roseobacters are limited. Thus, a comparative genome analysis of functions likely to contribute to, or even define, different colonizing abilities can provide a more holistic view of how widely distributed and conserved these features are among diverse clade members and may facilitate hypothesis-driven research in some areas.     

Marine actinobacteria associated with marine organisms and their potentials in producing pharmaceutical natural products

Actinobacteria are ubiquitous in the marine environment, playing an important ecological role in the recycling of refractory biomaterials and producing novel natural products with pharmic applications. Actinobacteria have been detected or isolated from the marine creatures such as sponges, corals, mollusks, ascidians, seaweeds, and seagrass. Marine organism-associated actinobacterial 16S rRNA gene sequences, i.e., 3,003 sequences, deposited in the NCBI database clearly revealed enormous numbers of actinobacteria associated with marine organisms. For example, RDP classification of these sequences showed that 112 and 62 actinobacterial genera were associated with the sponges and corals, respectively. In most cases, it is expected that these actinobacteria protect the host against pathogens by producing bioactive compounds. Natural products investigation and functional gene screening of the actinobacteria associated with the marine organisms revealed that they can synthesize numerous natural products including polyketides, isoprenoids, phenazines, peptides, indolocarbazoles, sterols, and others. These compounds showed anticancer, antimicrobial, antiparasitic, neurological, antioxidant, and anti-HIV activities. Therefore, marine organism-associated actinobacteria represent an important resource for marine drugs. It is an upcoming field of research to search for novel actinobacteria and pharmaceutical natural products from actinobacteria associated with the marine organisms. In this review, we attempt to summarize the present knowledge on the diversity and natural products production of actinobacteria associated with the marine organisms, based on the publications from 1991 to 2013.     

海绵生物活性物质及海绵细胞离体培养

介绍了来自海绵的生物活性物质种类、分布及其潜在的应用价值。讨论了其作为抗癌、抗病毒、抗细菌等药用的生物活性物质及其相关的海绵种属 ;强调海绵生物活性物质的商业化和临床应用所面临的“供给短缺问题”。作为解决这一问题的途径之一 ,海绵细胞离体培养是最有前景的技术。讨论了海绵细胞离体培养技术的研究现状 ,存在的问题及未来的发展趋势。对我国海域的海绵生物活性物质的研究开发现状进行总结 ,强调海绵研究对开发具有我国自主知识产权的新药、新化合物的必要性及重要性 ,并提出进行研发的可能优先领域     

Isolation of Broad-Host-Range Replicons from Marine Sediment Bacteria

Naturally occurring plasmids isolated from heterotrophic bacterial isolates originating from coastal California marine sediments were characterized by analyzing their incompatibility and replication properties. Previously, we reported on the lack of DNA homology between plasmids from the culturable bacterial population of marine sediments and the replicon probes specific for a number of well-characterized incompatibility and replication groups (P. A. Sobecky, T. J. Mincer, M. C. Chang, and D. R. Helinski, Appl. Environ. Microbiol. 63:888–895, 1997). In the present study we isolated 1.8- to 2.3-kb fragments that contain functional replication origins from one relatively large (30-kb) and three small (<10-kb) naturally occurring plasmids present in different marine isolates. 16S rRNA sequence analyses indicated that the four plasmid-bearing marine isolates belonged to the α and γ subclasses of the class Proteobacteria. Three of the marine sediment isolates are related to the γ-3 subclass organisms Vibrio splendidus and Vibrio fischeri, while the fourth isolate may be related to Roseobacter litoralis. Sequence analysis of the plasmid replication regions revealed the presence of features common to replication origins of well-characterized plasmids from clinical bacterial isolates, suggesting that there may be similar mechanisms for plasmid replication initiation in the indigenous plasmids of gram-negative marine sediment bacteria. In addition to replication in Escherichia coli DH5α and C2110, the host ranges of the plasmid replicons, designated repSD41, repSD121, repSD164, and repSD172, extended to marine species belonging to the genera Achromobacter, Pseudomonas, Serratia, and Vibrio. While sequence analysis of repSD41 and repSD121 revealed considerable stretches of homology between the two fragments, these regions do not display incompatibility properties against each other. The replication origin repSD41 was detected in 5% of the culturable plasmid-bearing marine sediment bacterial isolates, whereas the replication origins repSD164 and repSD172 were not detected in any plasmid-bearing bacteria other than the parental isolates. Microbial community DNA extracted from samples collected in November 1995 and June 1997 and amplified by PCR yielded positive signals when they were hybridized with probes specific for repSD41 and repSD172 replication sequences. In contrast, replication sequences specific for repSD164 were not detected in the DNA extracted from marine sediment microbial communities.  The maintenance and horizontal transfer of extrachromosomal elements provide one mechanism by which microbial communities can rapidly adapt to changes in environmental conditions. This adaptation can be in the form of plasmid rearrangements and duplications (18, 40), a change in the plasmid copy number (40, 54), or lateral or horizontal movement of plasmids within bacterial populations. An example demonstrating the importance of plasmid-mediated genetic adaptation in natural microbial communities, likely caused by lateral transfer, is the increased frequencies (2- to 10-fold) of catabolic plasmids reported in bacterial isolates obtained from polluted marine and freshwater environments compared to isolates from nonpolluted or less impacted ecosystems (8, 23, 43). Plasmids also play a major role in promoting the widespread distribution of antibiotic resistance genes attributed to the intense and increased use of antibiotics (42).The ability of plasmids to self-transfer or to be mobilized by transfer-proficient plasmids and the ability to replicate in different bacterial hosts are key factors in the spread of plasmid-encoded genes within microbial communities. Plasmids which are considered to have broad host ranges in nature have the potential to significantly affect the microbial community structure and function due to their ability to replicate and be maintained in members of distantly related genera. Thus, to better understand gene flux in natural systems and hence the potential role of plasmids in promoting horizontal transfer within microbial communities, knowledge of the distribution, diversity, and host ranges of naturally occurring plasmids is necessary.At present, most indigenous plasmids from marine and freshwater systems have been only partially characterized with respect to host range, replication mechanisms, incompatibility groups, and conjugal abilities. Plasmids containing similar or related replication systems are considered incompatible if they cannot coexist in a host cell (12, 41). This trait has facilitated the grouping of plasmids from gram-negative bacteria, mainly members of the family Enterobacteriaceae, into more than 30 different incompatibility groups (3). While molecularly based plasmid classification or replicon typing by using DNA sequences of replication origins and incompatibility loci of well-characterized plasmids has been useful in classifying plasmids from bacterial isolates of medical importance (9, 10, 14), plasmids from various marine microbial communities, including sediments, biofilms, bulk water, and the marine air-water interface, have been recently shown to contain incompatibility and replication regions unrelated to those currently defined (11, 53).The present study was undertaken to characterize, at the molecular level, the replication and incompatibility loci of naturally occurring plasmids isolated from gram-negative marine heterotrophs for use as replicon probes to classify and type, at the molecular level, plasmids present in bacterial populations of marine sediments. Replication origins were obtained from plasmids ranging in size from 6 to 30 kb isolated from culturable bacteria of coastal California marine sediments (53). Phylogenetic analysis indicated that the plasmids were initially isolated from bacteria belonging to the α and γ-3 subclasses of the class Proteobacteria. Although a sequence and hybridization analysis of the replication origins from the marine plasmids confirmed the lack of homology with previously described plasmids, the replication regions contained features commonly found in previously characterized plasmid replication origins. The replication origins of the naturally occurring plasmids appear to have a broad host range, as indicated by their ability to replicate in members of diverse gram-negative marine genera. In addition to molecular characterization of the indigenous plasmids, the persistence of the replicons in marine sediment bacterial populations was determined by PCR amplification of microbial community DNA extracted on different dates and examined for the presence of homologous plasmid replication sequences.     

Mixotrophic Protists In Marine and Freshwater Ecosystems

ABSTRACT Some protists from both marine and freshwater environments function at more than one trophic level by combining photosynthesis and panicle ingestion. Photosynthetic algae from several taxa (most commonly chrysomonads and dinoflagellates) have been reported to ingest living prey or nonliving particles, presumably obtaining part of their carbon and/or nutrients from phagocytosis. Conversely, some ciliates and sarcodines sequester chloroplasts after ingestion of algal prey. Plastid retention or "chloroplast symbiosis" by protists was first demonstrated < 20 years ago in a benthic foraminiferan. Although chloroplasts do not divide within these mixotrophic protists, they continue to function photosynthetically and may contribute to nutrition. Sarcodines and ciliates that harbor endosymbiotic algae could be considered mixotrophic but are not covered in detail here. the role of mixotrophy in the growth of protists and the impact of their grazing on prey populations have received increasing attention. Mixotrophic protists vary in their photosynthetic and ingestion capabilities, and thus, in the relative contribution of photosynthesis and phagotrophy to their nutrition. Abundant in both marine and freshwaters, they are potentially important predators of algae and bacteria in some systems. Mixotrophy may make a stronger link between the microbial and classic planktonic food webs by increasing trophic efficiency.     

Marine actinomycete diversity and natural product discovery

Microbial natural products remain an important resource for drug discovery yet the microorganisms inhabiting the worlds oceans have largely been overlooked in this regard. The recent discovery of novel secondary metabolites from taxonomically unique populations of marine actinomycetes suggests that these bacteria add an important new dimension to microbial natural product research. Continued efforts to characterize marine actinomycete diversity and how adaptations to the marine environment affect secondary metabolite production will create a better understanding of the potential utility of these bacteria as a source of useful products for biotechnology.     

Marine invertebrates,model organisms,and the modern synthesis: epistemic values,evo-devo,and exclusion

A central reason that undergirds the significance of evo-devo is the claim that development was left out of the Modern synthesis. This claim turns out to be quite complicated, both in terms of whether development was genuinely excluded and how to understand the different kinds of embryological research that might have contributed. The present paper reevaluates this central claim by focusing on the practice of model organism choice. Through a survey of examples utilized in the literature of the Modern synthesis, I identify a previously overlooked feature: exclusion of research on marine invertebrates. Understanding the import of this pattern requires interpreting it in terms of two epistemic values operating in biological research: theoretical generality and explanatory completeness. In tandem, these values clarify and enhance the significance of this exclusion. The absence of marine invertebrates implied both a lack of generality in the resulting theory and a lack of completeness with respect to particular evolutionary problems, such as evolvability and the origin of novelty. These problems were salient to embryological researchers aware of the variation and diversity of larval forms in marine invertebrates. In closing, I apply this analysis to model organism choice in evo-devo and discuss its relevance for an extended evolutionary synthesis.

Nonreductive Iron Uptake Mechanism in the Marine Alveolate Chromera velia

Chromera velia is a newly cultured photosynthetic marine alveolate. This microalga has a high iron requirement for respiration and photosynthesis, although its natural environment contains less than 1 nm of this metal. We found that this organism uses a novel mechanism of iron uptake, differing from the classic reductive and siderophore-mediated iron uptake systems characterized in the model yeast Saccharomyces cerevisiae and present in most yeasts and terrestrial plants. C. velia has no trans-plasma membrane electron transfer system, and thus cannot reduce extracellular ferric chelates. It is also unable to use hydroxamate siderophores as iron sources. Iron uptake from ferric citrate by C. velia is not inhibited by a ferrous chelator, but the rate of uptake is strongly decreased by increasing the ferric ligand (citrate) concentration. The cell wall contains a large number of iron binding sites, allowing the cells to concentrate iron in the vicinity of the transport sites. We describe a model of iron uptake in which aqueous ferric ions are first concentrated in the cell wall before being taken up by the cells without prior reduction. We discuss our results in relation to the strategies used by the phytoplankton to take up iron in the oceans.Chromera velia is a newly cultured marine alveolate containing a photosynthetic plastid phylogenetically related to vestigial plastids in apicomplexan (Moore et al., 2008). It represents the closest free-living photosynthetic relative to apicomplexan parasites, thus providing a powerful model to study the evolution of eukaryotic adaptability (Moore et al., 2008). To gain further insight into the biology of this organism, the genome of which remains unsequenced, we investigated its iron metabolism and its mechanisms of iron uptake. We compared the data obtained with other phytoplanktonic organisms sharing the same ecological niche, and with a terrestrial unicellular eukaryote, the yeast Saccharomyces cerevisiae. S. cerevisiae is phylogenetically distant from C. velia, but its mechanisms of iron uptake are well characterized, and thus constitutes a useful model in these studies.Iron uptake by terrestrial microorganisms and plants is mostly based on the use of two main strategies, both of which have been previously characterized in S. cerevisiae. The first strategy is the reductive mechanism of uptake. Extracellular ferric complexes are first dissociated by reduction, via trans-plasma membrane electron transfer catalyzed by specialized flavohemoproteins (Fre). Free iron is then imported by a high-affinity permease system (Ftr1) coupled to a copper-dependent oxidase (Fet3), allowing iron to be channeled through the plasma membrane. In the second strategy, the siderophore-mediated mechanism, siderophores excreted by the cells or produced by other bacterial or fungal species are taken up without prior dissociation, via specific, copper-independent high-affinity receptors. Iron is then dissociated from the siderophores inside the cells, probably by reduction (for review, see Kosman, 2003; Philpott, 2006). Chlamydomonas reinhardtii is a photosynthetic eukaryotic model organism for the study of iron homeostasis, which shares with yeast the strategy 1 of iron uptake (copper-dependent reductive iron uptake; Merchant et al., 2006).Much less is known about the strategies used by marine phytoplankton to acquire iron. Some data suggest that these two strategies are used by some marine microalgae (Soria-Dengg and Horstmann, 1995; Allen et al., 2008). However, for most marine unicellular eukaryotes the mechanisms of iron assimilation are completely unknown. The strategies used by these organisms to acquire iron must have evolved to adapt to the very particular conditions that prevail in their surrounding natural environment: The transition metal composition of the ocean differs greatly from that of terrestrial environments (Butler, 1998). In particular, iron levels in surface seawater are extremely low (0.02–1 nm; Turner et al., 2001). Therefore a strategy of iron uptake operating efficiently in a terrestrial environment that contains iron at a micromolar level may be inefficient in a marine environment. No classic iron uptake system with an affinity constant in the nanomolar range has ever been found. Additionally, the marine environment imposes physical limits on the classic strategies of uptake, including the high diffusion rate of the species of interest (siderophores or reduced iron; Völker and Wolf-Gladrow, 1999). It is well known that the low levels of iron limits primary production of phytoplankton and carbon fluxes across vast regions of the world’s oceans (Coale et al., 2004; Pollard et al., 2009). It is thus of particular interest to elucidate the molecular mechanisms underlying acquisition of iron by marine phytoplankton and to determine which iron sources are preferentially assimilated with regards to the yield of carbon fixation.In this study, we investigated the mechanisms of iron uptake by C. velia, and found that this organism uses a nonreductive uptake system of ferric ions, which are first concentrated in the cell wall. Our findings provide a better understanding of the biology of this organism, and highlights the need for further study on the mechanisms of iron acquisition in marine phytoplankton.     

Marine microbial natural products in antifouling coatings

Ecological problems associated with current antifouling technologies have increased interest in the natural strategies that marine organisms use to keep their surfaces clean and free from fouling. Bacteria isolated from living surfaces in the marine environment have been shown to produce chemicals that are potential antifoulants. Active compounds from the cells and culture supernatant of two bacterial strains, FS‐55 and NudMB50–11, isolated from surface of the seaweed, Fucus serratus, and the nudibranch, Archidoris pseudoargus, respectively, were extracted using solid phase extraction. The extracts were combined with acrylic base paint resin and assayed for antifouling activity by measuring their ability to inhibit the growth of fouling bacteria. These formulations were found to be active against fouling bacteria isolated from marine surfaces. The formulation of antifouling paints that incorporate marine microbial natural products is reported here for the first time. This is a significant advance towards the production of an environmentally friendly antifouling paint that utilises a sustainable supply of natural biodegradable compounds.     

Drought stress and recovery of riparian cottonwoods due to water table alteration along Willow Creek,Alberta

A 5-m-deep gravel pit was excavated from 1996 to 1998 in the floodplain between Willow Creek, Alberta, and a grove of balsam poplars ('cottonwoods', Populus balsamifera L.) and water level at the pit was lowered 2.5 m through pumping. This interrupted the infiltration of stream water into the riparian groundwater and imposed drought stress on the cottonwoods. Trees in the drought-affected grove displayed extensive leaf senescence and abscission in late August 1998, while trees in nearby control groves remained green until autumnal senescence in late September. The precocious senescence was accompanied by a two-thirds reduction in leaf stomatal conductance (g _s) but mid-day leaf xylem water potentials (ψ_l) were only slightly reduced (?1.55 vs 1.42 MPa). Pumping ceased in 1999, the pit was partially refilled, and the hydraulic linkage between the stream and the riparian zone recovered. Subsequently in August 1999, g _s and ψ_l were similar for trees in the affected and control groves and senescence phenologies were similar in 1999 and 2000. Annual branch growth increments varied 3-fold across years between 1994 and 1999, but there was no reduction in these growth increments in the drought-affected trees in 1998 or 1999. This study supports the hydraulic linkage between a stream and the adjacent riparian zone in a semi-arid region and demonstrates the vulnerability of riparian cottonwoods to drought due to water table depletion. It also indicates rapid physiological recovery of cottonwoods following restoration of water availability.     

Production of a New Thiopeptide Antibiotic,TP-1161, by a Marine Nocardiopsis Species

Twenty-seven marine sediment- and sponge-derived actinomycetes with a preference for or dependence on seawater for growth were classified at the genus level using molecular taxonomy. Their potential to produce bioactive secondary metabolites was analyzed by PCR screening for genes involved in polyketide and nonribosomal peptide antibiotic synthesis. Using microwell cultures, conditions for the production of antibacterial and antifungal compounds were identified for 15 of the 27 isolates subjected to this screening. Nine of the 15 active extracts were also active against multiresistant Gram-positive bacterial and/or fungal indicator organisms, including vancomycin-resistant Enterococcus faecium and multidrug-resistant Candida albicans. Activity-guided fractionation of fermentation extracts of isolate TFS65-07, showing strong antibacterial activity and classified as a Nocardiopsis species, allowed the identification and purification of the active compound. Structure elucidation revealed this compound to be a new thiopeptide antibiotic with a rare aminoacetone moiety. The in vitro antibacterial activity of this thiopeptide, designated TP-1161, against a panel of bacterial strains was determined.Natural products remain the most prolific source of new antimicrobials, and the chemical diversity of natural compounds is still unmatched by combinatorial chemistry approaches (9, 31). While the latter has been successfully applied for lead optimization, it basically failed to deliver genuinely new pharmacophores, especially in the field of antimicrobials (31), mainly due to limitations in the structural variety of compounds represented in combinatorial libraries.Most of the antibiotics in clinical use today have been developed from compounds isolated from bacteria and fungi, with members of the actinobacteria being the dominant source (34). Traditionally, most of these antimicrobials have been isolated from soil-derived actinomycetes of the genus Streptomyces. However, isolation strategies in recent years have been directed to unexploited environments like marine sources (40). Bioprospecting efforts focusing on the isolation and screening of actinobacteria from ocean habitats (25, 27) have added new biodiversity to the order Actinomycetales and revealed a range of novel natural products of pharmacological value. The existence of marine actinobacterial species physiologically and phylogenetically distinct from their terrestrial relatives is now widely accepted, and new taxonomic groups of marine actinomycetes have been described for at least six different families within the order Actinomycetales (12). Apart from being phylogenetically distinct from their terrestrial relatives, marine isolates have been shown to possess specific physiological adaptations (e.g., to high salinity/osmolarity and pressure) to their maritime surroundings and many were found to produce novel and chemically diverse secondary metabolites (10, 13, 35).Most streptomycetes and other filamentous actinomycetes possess numerous gene clusters for the biosynthesis of secondary metabolites (2, 32), and genome sequence studies have shown that large portions of their genomes are devoted to secondary metabolite biosynthesis. Twenty gene clusters coding for known or predicted secondary metabolites were identified in the 8.7-Mb genome of Streptomyces coelicolor A3(2) (2), and 6.4% of the 8.7-Mb genome of Streptomyces avermitilis is dedicated to gene clusters for secondary metabolite biosynthesis (32). The marine actinomycete Salinispora allocates nearly 10% of its 5.2-Mb genome to 17 diverse biosynthetic loci, including polyketide synthases (PKSs), nonribosomal peptide synthetases (NRPSs), and several hybrid clusters (4, 43). Many medicinally important natural products, including antibacterials and antifungals, are synthesized by these multimodular assembly lines (14), and genome mining for secondary metabolite gene clusters has become a common tool to assess the genetic capability of bacteria to produce novel bioactive compounds. However, even for well-studied model antibiotic producers like S. coelicolor A3(2), discrepancies between the number of known metabolites on the one hand and the number of pathways identified from genomic data on the other hand are tremendous (2). These discrepancies can only be explained by the facts that most gene clusters for secondary metabolites are silenced under standard laboratory cultivation conditions and that an expression or upregulation of these pathways is only triggered in response to certain environmental signals. It has been shown that by cultivating bacteria under a range of conditions, it is possible to obtain products of many of these “orphan” biosynthetic pathways (4). Using the OSMAC (one strain-many compounds) approach, Bode et al. were able to isolate more than 100 compounds comprising 25 structural classes from only six microorganisms (4).In this study, marine sediment-derived actinomycete isolates were analyzed for the production of antimicrobial secondary metabolites by using microwell plate fermentations and a range of media and conditions. This approach led to the isolation of a new thiopeptide antibiotic, designated TP-1161, produced by a marine sediment-derived Nocardiopsis isolate. Here we report the isolation and structural and biological characterization of TP-1161.     

Amidohydrolase activity,soil N status,and the invasive crucifer Lepidium latifolium

Wetlands and riparian habitats in the western United States are being invaded by the exotic crucifer Lepidium latifolium (perennial pepperweed, tall whitetop). It was hypothesized that L. latifolium was an effective competitor due to its ability to make available and take up more nitrogen than vegetation it is replacing. The hypothesis was tested by comparing amidohydrolase activities, available soil N, 30 day aerobic N-mineralization rates, and plant uptake of N in paired L. latifolium invaded and non-invaded plots occupied by Elytrigia elongata (tall wheatgrass). Attributes were measured by date (June 1998, September 1998, April 1999, and May 2000) and by soil depth (0–15, 15–30, 30–50, and 50–86 cm). Lepidium latifolium invaded sites had significantly (p 0.05) greater urease, amidase, glutaminase, and asparaginase activities than sites occupied by E. elongata for most dates and soil depths. In addition, despite far greater uptake of N per unit area, L. latifolium sites still had significantly greater available N and N-mineralization potentials than E. elongata for most dates and depths. In general, enzyme activities significantly correlated with available soil N, with a stronger relationship for sites invaded by L. latifolium. There were few significant linear correlations of enzyme activities with net N mineralization potentials for L. latifolium sites, but many for sites occupied by E. elongata. These data support the working hypothesis.     

Biodiversity of brachyuran crabs (Crustacea: Decapoda) from non-consolidated sublittoral bottom on the northern coast of São Paulo State, Brazil

The brachyuran community of the coast of São Paulo State is represented by about 188 species of crabs inhabiting different kinds of coastal marine environments. The biodiversity of brachyurans found on non-consolidated sublittoral bottom was investigated. The Ubatuba region (Ubatumirim, Ubatuba and Mar Virado bays, Couves and Mar Virado Islands, offshore region) was sampled for 3 years (1998–2000), at depths of 2–40 m. All sampling was performed using a fishing boat equipped with two double-rig nets. We collected 79 brachyuran species representing 9 superfamilies (4 Dromioidea, 1 Homoloidea, 2 Calappoidea, 5 Leucosioidea, 20 Majoidea, 7 Parthenopoidea, 17 Portunoidea, 18 Xanthoidea, and 5 Pinnotheroidea) and 41 genera. Ubatuba bay showed the greatest species richness with 50 species, followed by Ubatumirim with 45 and Mar Virado with 29. The number of species collected represents about 57% of the known species of crabs already reported for the shore of São Paulo State. It is worth noticing that this percentage is restricted only to non-consolidated sublittoral bottom. This fact indicates a great biodiversity of the habitat in this studied region, probably one to the diversity of habitat types present in the bays.