Effective Competitor Research Articles

Structure-based discovery of a new type of scaffold compound as binding competitors for protein-bound Uremic Toxins.

Protein-bound uremic toxins (PBUTs) are the main cause of uremia, but traditional hemodialysis is ineffective in removing them because of their strong ability to bind to human serum albumin (HSA), highlighting the need for new treatments. In this study, first, structure-based docking was used to screen a diverse library of 200,376 virtual compounds against the active sites I and II. After two rounds of docking screening, 3944 candidate molecules were obtained. Second, 23 candidate molecules were obtained after ADMET prediction and toxicity analysis. Five candidate molecules were finally obtained after visual analysis and MM-PBSA calculations. We subsequently assessed their competitive displacement efficiency through a microdialysis experiment, and the results revealed that ZINC000008791789, ZINC000012297018, and ZINC000012296493 are promising binding competitors for PBUTs, as they have higher dialysis efficiency than the optimal displacer LA, approximately double the dialysis efficiency. The other two molecules, ZINC000031161007 and ZINC000004090361, although less efficient than LA, still outperformed the control group. Notably, four of them shared the same molecular scaffold, and three of them contained a flavonoid group. These findings provide a foundation for the development of more effective PBUT binding competitors, potentially benefiting uremia patients in the future.

The Role of Internships in Guyana's Development

Guyana’s development is dependent upon, among other things, a well-educated workforce with the necessary skills to exploit its natural resources and to make the nation an effective global competitor. In this regard, the University of Guyana (UG) has a critical role to play by providing its graduates with the education needed to meet the demands of their potential employers. Unfortunately, many organisations have publicly lamented the deficiency of practical skills of UG’s graduates. One available strategic option is for UG to consider a wider use of internships. Internships are valuable because student-interns: (i) learn to apply the theoretical knowledge to real life industrial applications, (ii) are better prepared for entry-level jobs in their field; and (iii) learn by experiencing the actual day-to-day operations of a corporation by attending meetings and participating in actual projects. The objective of this paper is to show how UG can use internships to improve the human capital stock of its graduates. We examine some best practices of internship programmes and demonstrate how internships can be beneficial to students, universities, and companies.

Analysis of Hydroponic Green Lettuce Marketing Strategy at PT Amboja Global Lestari, Sleman Regency, Yogyakarta

Vegetable business opportunities, one of which is green lettuce, is still quite high. PT Amboja Global Lestari is a producer of hydroponic-based green lettuce. There is competition from green lettuce producers in Yogyakarta province and surrounding areas which significantly affects the sales level of PT Amboja Global Lestari's hydroponic green lettuce, so it is necessary to plan a strategy to be able to win the competition. The purpose of this study is to identify internal and external factors of hydroponic green lettuce marketing, analyze alternative marketing strategies, and determine the priorities of hydroponic green lettuce marketing strategies. The basic method of research uses a descriptive method with a qualitative approach. The data analysis method uses IFE Matrix, EFE Matrix, IE Matrix, SWOT Matrix, QSPM. The results of data analysis show internal factors that are the company's main strength in marketing hydroponic green lettuce, namely, quality green lettuce products, good service to consumers, guaranteed product quality guarantees to consumers, and online and offline promotions and sales are running well, with the highest score of 0.31, while for the main weakness, the distance to the hydroponic garden is quite far with the lowest score of 0.09. The main external opportunities are high consumer demand for vegetables, and there are often exhibitions with a score of 0.35, while the main threats are, the increase in new competitors, effective competitor marketing online and offline, and disease and fungal attacks, with a score of 0.21. IE Matrix Analysis shows that the company is in a position to grow and develop. The SWOT Matrix Analysis resulted in six alternative marketing strategies. QSPM analysis resulted in the main strategy priority of hydroponic green lettuce marketing, namely, increasing the quality and quantity of hydroponic green lettuce with a total TAS value of 7,615.

Fluorescence polarization reveals a possible displacement model of competition in PRC2:RNA:DNA interactions

PRC2 is a histone methyltransferase that acts on histone subunit H3 at lysine 27 to repress chromatin state and inhibit gene expression. The interactions between PRC2 and RNA have been heavily studied in vivo and in vitro with conflicting results reported on the relationship, but there is less data on interactions between PRC2 and DNA. Fluorescence polarization-based methodology was used with various RNA and DNA species to study the binding kinetics of PRC2 with RNA and DNA. Previous data indicate that PRC2 has a relatively high affinity for DNA species that are rich in consecutive G and C nucleotides. Double-stranded DNA species with lengths of 50-60 bp were designed for this project. Fluorescence polarization binding experiments were used to identify the general binding affinity of the DNA and RNA species to PRC2 by calculating the Kd apparent for the binding curve. After the apparent binding affinities were determined, various FP-competition experiments were performed to determine if each DNA species could be competed off by an RNA species or itself, and vice versa. These results showed that the DNA species were more effective competitors although the RNA species were stronger binders. These results suggest a mechanism for RNA-mediated PRC2 regulation that could reconcile the conflicting experimental results and interpretations of past experiments. Further FP-based Kd experiments under varying salt concentrations revealed PRC2 has ionic interactions with DNA that are not seen with RNA. This suggests PRC2 has extra unique interactions with DNA, which could explain the differing effectiveness of DNA versus RNA as competitors. Altogether, the results imply that DNA has additional contacts with PRC2 that limit its displacement by RNA, allowing for RNA to guide PRC2 to its target genetic loci and then for PRC2 to deposit its methyl marks without being sequestered by RNA. Lay Summary PRC2 is a protein involved in gene expression. Its role is to repress chromatin state, inhibiting gene expression during development. This protein is vital to developmentand has been linked to multiple diseases of the body including skin cancer and other forms. When the protein is doing its job correctly, it interacts with DNA in order to repress chromatin. RNA has been shown to be vital in anchoring PRC2 in the correct spot on chromatin, but studies have shown conflicting results in how it interacts with PRC2. In order to study how PRC2 interacts with DNA and RNA, fluorescence polarization-based methodology was used with various RNA and DNA species to study their binding kinetics to PRC2 individually. After the apparent binding affinities were determined, various FP-competition experiments were performed to determine if each DNA species could be competed off by an RNA species or itself, and vice versa. The DNA species were more effective competitors although the RNA species were stronger binders. These results along with other experiments revealed PRC2 has ionic interactions with DNA that are unique to DNA, which explains how the DNA species could compete off RNA. Altogether, the results imply that DNA has additional contacts with PRC2 that limit its displacement by RNA, allowing for RNA to guide PRC2 to its target genetic loci and then for PRC2 to deposit its methyl marks without being sequestered by RNA. To see the complete thesis, please visit https://scholar.colorado.edu/concern/undergraduate_honors_theses/5x21tg835.

Growth response to nitrate enrichment helps facilitate success of an alien Potamogeton in New Zealand streams

Motivated by stream ecosystem degradation by eutrophication, we mimicked slow flowing lowland stream conditions with a novel experimental setup to further our understanding of aquatic plant responses to increases in nitrate and light. We conducted a mesocosm growth experiment of two species from the genus Potamogeton: P. crispus (alien) and P. ochreatus (native), grown at four nitrate and four light levels. We hypothesised that (i) internal nutrient status of the plants would scale with water column nutrient concentration, and that (ii) plant performance would reflect the nutrient status of the plant. Furthermore, we hypothesised that (iii) a low irradiance level would negate the effects of an increased nitrate level. In relation to (ii) we hypothesised that (iv) the traits of the alien species would enable it to outperform the native species where both the availability of light and nutrient resources was high. Internal tissue N content was broadly similar in the two higher (>250 μg NO3− L−1) and the two lower nutrient treatments (<20 μg NO3− L−1) in both species and plants were therefore collapsed into high and low N-groups. High-N individuals had higher growth rates than low-N ones regardless of species or light treatment and plants had reduced growth rates at the lowest light treatment, however this response was less evident for P. crispus. The highest growth rate was found at the high-N individuals of P. crispus at the highest light treatment, and correspondingly, in this treatment this species exhibited an increase in branching degree and lateral spread from the low-N plants. As P. crispus spreads by fragmentation, our results show it to be a highly effective competitor in anthropogenically impacted areas compared to its native counterpart. Our study exemplifies how light can influence eutrophication responses of plants and how both need to be accounted for in management decisions.

Tracking nitrogen allocation to proteome biosynthesis in a marine microbial community.

Microbial growth in many environments is limited by nitrogen availability, yet there is limited understanding of how complex communities compete for and allocate this resource. Here we develop a broadly applicable approach to track biosynthetic incorporation of 15N-labelled nitrogen substrates into microbial community proteomes, enabling quantification of protein turnover and N allocation to specific cellular functions in individual taxa. Application to oligotrophic ocean surface water identifies taxa-specific substrate preferences and a distinct subset of protein functions undergoing active biosynthesis. The cyanobacterium Prochlorococcus is the most effective competitor for acquisition of ammonium and urea and shifts its proteomic allocation of N over the day/night cycle. Our approach reveals that infrastructure and protein-turnover functions comprise substantial biosynthetic demand for N in Prochlorococcus and a range of other microbial taxa. The direct interrogation of the proteomic underpinnings of N limitation with 15N-tracking proteomics illuminates how nutrient stress differentially influences metabolism in co-existing microbes.

Influence of suspended solid particles on calcium carbonate fouling in dripper labyrinths

Calcium carbonate (CaCO3) fouling process in dripper prototypes was studied in the absence and presence of suspended solid particles (SSP) at concentrations of 125 and 500 mg L−1. Eleven flat and non-pressure-compensating dripper prototypes were evaluated. Five prototypes (Model A) present flow with well-developed vortices, whereas the other six prototypes (Model B) present more uniform flow with undeveloped vortices. Water with hardness of 200 and 300 mg L−1 as CaCO3 was used in the experiments. The dripper prototypes operated for 200 h, and the discharge variation rate (Dra) was determined every 40 h. Images of the interior of the labyrinths were acquired to investigate the fouling patterns. The mass of material fouling the labyrinth of the prototypes was determined and correlated to the geometric parameters of the labyrinths. The deposited material was analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The SSP directly influenced the CaCO3 fouling processes. In the absence of SSP, heterogeneous nucleation was dominant in the prototype walls and occurred uniformly throughout the labyrinth, interfering directly in the Dra of the model B prototypes. The model A prototypes were more resistant to clogging and did not clog during the experiments. Once added to the water, the SSP functioned as an effective competitor of CaCO3 nucleation and growth sites; thus, heterogeneous nucleation started occurring preferably on the SSP surface, reducing the fouling in the labyrinth walls. The prototypes that clogged in the tests in the absence of SSP were resistant to clogging in the SSP concentration of 500 mg L−1. The presence of SSP changed the crystal habit of CaCO3, and it precipitated in the form of calcite. The nucleation of CaCO3 directly on the SSP surface is interesting from the point of view of clogging processes, and drippers with better sediment transport capacity are beneficial.

When domestication bottleneck meets weed

Crop domestication is a unique pattern of plant evolution, commonly referred to as the process of generation of cultivated crops from wild species due to morphological and genetic transformation as a result of human intervention and selection. Studies on the relationship between weeds and crops in archaeology, evolutionary biology, and genetics have revolutionized our understanding of the role of weeds in the agroecosystem and of the intricacy of crop domestication. Weeds, generally being effective competitors of crops, are not the targets of human cultivation; however, like crops, they can adapt to human-made habitats and thereby are under unintentional human selection.

Soft but Strong: Software-Based Innovation and Product Differentiation in the IT Hardware Industry

It has been argued in recent years that software is a significant value-creating factor within the manufacturing sector, leading to an increased interest in understanding the mechanisms by which firms may benefit from software-based innovation. Empirical work in evaluating these mechanisms, however, remains underdeveloped. In this paper, we examine one such process through which software-based innovation may provide value for information technology hardware firms in the U.S. Specifically, we examine the influence of software patents on the extent to which firms are able to benefit from product differentiation in their product markets. Using data on over 380,000 patent grants for innovations filed by 730 public IT hardware firms over the time period 1996-2015, we find that greater levels of software-based innovation within the firm are associated with higher levels of product differentiation in product markets: increases in the intensity of software patents within the firm’s patent stock, which we refer to as software intensity, are associated with lower total similarity of product offerings, relative to those offered by rivals, as well as fewer effective competitors in the market. Furthermore, using a different dataset consisting of 23,000 new IT hardware product announcements, we show that firms with greater software intensity subsequently launch a higher number of new products. Moreover, these firms are more likely to launch products that are not only differentiated from those of rivals but also distinct from their own product lines. Our research contributes to the emerging literature on software-based innovation by substantiating an important mechanism through which software helps transform industry sectors, specifically through product differentiation.

Time after time: detecting annual patterns in stream bacterial biofilm communities.

SummaryTo quantify the major environmental drivers of stream bacterial population dynamics, we modelled temporal differences in stream bacterial communities to quantify community shifts, including those relating to cyclical seasonal variation and more sporadic bloom events. We applied Illumina MiSeq 16S rRNA bacterial gene sequencing of 892 stream biofilm samples, collected monthly for 36‐months from six streams. The streams were located a maximum of 118 km apart and drained three different catchment types (forest, urban and rural land uses). We identified repeatable seasonal patterns among bacterial taxa, allowing their separation into three ecological groupings, those following linear, bloom/trough and repeated, seasonal trends. Various physicochemical parameters (light, water and air temperature, pH, dissolved oxygen, nutrients) were linked to temporal community changes. Our models indicate that bloom events and seasonal episodes modify biofilm bacterial populations, suggesting that distinct microbial taxa thrive during these events including non‐cyanobacterial community members. These models could aid in determining how temporal environmental changes affect community assembly and guide the selection of appropriate statistical models to capture future community responses to environmental change.

Competitive Interactions Between Microbial Siderophores and Humic-Like Binding Sites in European Shelf Sea Waters

Siderophores are low molecular weight high affinity iron chelates found at low concentrations in seawater. In this study we determined the total concentrations and identities of siderophores in extracts isolated from a shelf sea environment on the Northwest European shelf by high performance liquid chromatography coupled to high resolution inductively coupled plasma mass spectrometry (ICP-MS) in parallel to high resolution electrospray ionisation mass spectrometry (ESI-MS). We identified a total of 24 different siderophores in our samples via metal isotope profiling of masses detected by ESI-MS. Twenty three of the identified siderophores could be assigned to three siderophore families – ferrioxamines, amphibactins and marinobactins. In contrast, only 12 peaks could be resolved in iron chromatograms obtained via ICP-MS analysis. Comparison of results obtained by the two mass spectrometry detectors showed that neither method was able to detect and identify all siderophores present in the samples on its own. We assessed the impact of our observed total siderophore concentrations on iron speciation by calculating the distribution of iron species as a function of total siderophore concentrations at different iron concentrations representative of our study area. We considered competition for iron between siderophores, a humic like dissolved organic matter (DOM) fraction and hydroxide ions by combining an ion-pair model with a non-ideal competitive interaction (NICA)-Donnan model. We found that the overall impact of siderophores on iron biogeochemistry is low at concentrations of siderophore &amp;lt;100 pmol L-1, and that the dominant iron species present at siderophore concentrations of the order of a few tens of pmol L-1 will be iron bound to the humic like DOM fraction. Furthermore the heterogeneity of binding sites in the humic like DOM fraction means that other binding sites present in organic matter could be effective competitors for siderophores, especially at low iron concentrations. Our findings highlight the importance of binding site heterogeneity when considering the influence of different iron binding groups on iron speciation in the marine environment.

Compensatory dynamics of lotic algae break down nonlinearly with increasing nutrient enrichment.

One important mechanism governing the temporal maintenance of biodiversity is asynchrony in co-occurring competitors due to fluctuating environments (i.e., compensatory dynamics). Temporal niche partitioning has evolved in response to predictable oscillations in environmental conditions so that species may offset competition, but we do not yet have a clear understanding of how novel anthropogenic stressors alter seasonal patterns of succession. Many primary producers are nutrient limited, and enrichment may decrease the importance of environmental fluctuations that govern which species are effective competitors under naturally low nutrient regimes. Consequently, elevated nutrient concentrations may synchronize species responses to seasonality. By studying benthic algal assemblages over 2 years from 35 streams that spanned a wide gradient of nutrient enrichment, we found that compensatory dynamics characterizing seasonal succession under natural nutrient regimes broke down at relatively low levels of total phosphorus (P) enrichment (~ 25 μg/L). With increasing P more species were able to coexist at any given time, and seasonal variation in assemblage composition was characterized by synchronous swings in species biovolumes. We also observed much higher instability in assemblage biovolumes with declines in compensatory dynamics, which indicates that anthropogenic alteration of nutrient regimes can affect community stability by changing the dominant mode of seasonal succession. Our findings indicate that compensatory fluctuations of stream algae are driven by seasonality and provide insight about how nutrient enrichment alters evolved drivers of species coexistence.

Risk Assessment Approach for Software Development using Cause and Effect Analysis

In the industry of software development, the risk is the most effective competitor who tries to flop the project at any stage of development. Risk is a critical factor that is obscure and has the potential to wreak massive loss of the project in terms of money, time, and resources. It is also harmful to the credibility of the organization. Most of the organizations don’t focus on this factor, and as a result, might witness the project failing. Lack of risk assessment is very common in most of organizations. This paper introduces risk assessment factors and analyzes the various situations to tackle them. We investigate the most effective key risk variables cost, strategy, technique, operation, and some unknown/unpredictable factors. Based on these variables, survey and interviews are conducted and examined them. We applied empirical studies on these variables and map them on the cause and effect analysis technique. The proposed technique elaborates the factors behind these risk variables. After that, results and analysis of these variables have been incorporated to scale down the impact of risk.

Competitive Adsorption Processes at Clay Mineral Surfaces: A Coupled Experimental and Modeling Approach

Quantification of adsorption processes on clay mineral surfaces is often necessary to predict the extent and the evolution of contaminants’ migration in surficial and underground environments. Many studies have been dedicated to retention measurement as a function of pH and ionic strength in relation with the two main identified adsorption processes for clay minerals, that is, cation exchange on their basal surfaces and surface complexation on their edge surfaces. The latest process has been repeatedly assessed as an effective retention mechanism at circumneutral pH conditions, which often prevail in natural environments. This assessment must however be tempered by the lack of information about competitive processes that can take place with the numerous chemical species present in natural settings, compared to simplified systems investigated in laboratory experiments. In this study, we quantified experimentally the competition between Pb2+, Co2+, Zn2+, and Mg2+ for specific adsorption on montmorillonite edge surfaces. Zn2+ was an effective competitor with Pb2+ and Co2+, and our results showed also unambiguously the influence of Mg2+ concentration levels on the specific adsorption of Pb2+ and Co2+. Because of the high ionic strength used in the experiments, cation exchange with Mg2+ was dismissed as a possible reason for such competition process, leaving specific competitive adsorption on edge surfaces as a unique explanation for our observations. Modeling of Pb2+ adsorption data with a state-of-art electrostatic complexation model for montmorillonite edge surfaces, supported by state-of-the-art, made it possible to distinguish two types of possible competition driving forces: Zn2+ competition for adsorption site occupancy but also detrimental changes in surface electrostatic potential following Mg2+ adsorption on sites neighboring those of Pb2+ adsorption. Mg2+ competition observed in our experiment should apply in most of clayey environments. Consequently, adsorption data obtained on pure clay mineral phases, and the associated models that have been built based on these data without considering the geochemical background in competitive species, may overestimate the retention properties of clay minerals when applied to natural settings.

Soil properties are resilient despite grass invasion, fire, and grazing

AbstractKentucky bluegrass (Poa pratensisL.; hereafter referred to as bluegrass) is an invasive perennial grass that has become naturalized throughout the entire United States. This species is an effective competitor and produces abundant litter, which in turn creates a thick thatch layer. In the northern Great Plains, fire and grazing are effective management tools for reducing the thatch layer, promoting expression of native grasses and forbs, and improving forage quality. The overall objective of this research was to examine belowground characteristics under accumulated thatch in response to management with fire and grazing. Soil samples were collected from plots dominated by bluegrass with thatch and from plots one year after management with fire and season‐long grazing. Additionally, to understand immediate and in‐season effects of fire and grazing on soil properties, we sampled soil immediately before and at increasing time steps after spring fires and exposure to grazing. All soils were analyzed for carbon and nitrogen pools, microbial abundance and community structure, and decomposition rates. In general, belowground pools of carbon, nitrogen, and microbial communities were stable despite vegetation management treatments. However, prescribed burning caused a brief decline of labile carbon and decomposition rates in shallow soil, but both properties returned to prefire levels within one year after burning. Our observations indicate that the combination of fire and grazing has minimal effect on the soil and is effective at removing thatch and reducing bluegrass.

Is nuclear power sustainable in a carbon-free world? The case of Sweden

ABSTRACT Politicians and the public alike doubt the ability of nuclear power in the United States to compete as a significant low-carbon emission contributor to electricity production in a fully decarbonized electricity sector. Establishing whether or not these doubts are justified is challenged by the complexity of the highly disaggregated US electricity markets, including the highly varied mix of subsidies, production credits, and power purchase mandates that exist at the individual state level. The authors focus on answering the question of nuclear power’s competitiveness by examining the electricity market of Sweden, a nation which has already fully decarbonized its electricity sector, basing its electricity generation entirely on a mix of hydroelectric power, nuclear power, and the use of biofuels, with much smaller contributions from renewables such as solar PV and wind-generated power. In this market, nuclear power is an effective competitor against renewable power generation.

Saltwater spawning grounds of sea-run brown trout (Salmo trutta) in tidal waters of a major Norwegian river

Sea-run brown trout (Salmo trutta) have a highly phenotypically plastic life history that allows them to be effective colonizers and competitors in freshwater. This paper documents a previously unknown spawning behaviour in a brackish, tidally influenced estuary 14 km from the mouth of the Vosso River, a major Atlantic salmon- and sea-run brown trout–producing river in western Norway. Putative spawning gravel was observed, and sea-run brown trout deposited eggs that hatched in April. Survival of recruits was high (> 95%) in the tidal spawning gravel. These areas are strongly tidally influenced with a peak of 23.17 psu recorded at the lowest spawning ground. The observation of spawning so far from the river mouth may be unique in such a system with a long estuary but provides important insight into the biology of sea trout. Invasion of pink salmon, also known to spawn in estuaries, may negatively affect the competitive balance of sea trout with other salmonids in rivers where sea trout populations rely on recruitment from these relatively extreme spawning areas. Restoration of estuaries that have been modified by dredging or channelization may be important to ensure quality and heterogenous habitat for sea trout spawning given that haline spawning grounds could contribute to population resilience.

(-)-Epicatechin acts as a potent agonist of the membrane androgen receptor, ZIP9 (SLC39A9), to promote apoptosis of breast and prostate cancer cells

(-)-Epicatechin, a flavonoid present in high concentrations in foods such as green tea and cocoa, exerts beneficial and protective effects in numerous disease models, including anti-tumorigenesis and apoptosis in human breast and prostate cancer cells. Potential interactions of (-)-epicatechin and (+)-catechin with the membrane androgen receptor, ZIP9 (SLC39A9), which mediates androgen induction of apoptosis in these cancer cells, were investigated. Both (-)-epicatechin and (+)-catechin were effective competitors of [3H]-testosterone binding to PC-3 prostate cancer cells (nuclear androgen receptor-negative, nAR-null) overexpressing ZIP9 (PC3-ZIP9), with relative binding affinities of 75 % and 28 % that of testosterone, respectively. (-)-Epicatechin (200 nM) mimicked the effects of 100 nM testosterone in inducing apoptosis of PC3-ZIP9 cells, whereas (+)-catechin (concentration range 200 nM-1000 nM) did not significantly increase apoptosis and instead blocked the apoptotic response to testosterone. (-)-Epicatechin also activated androgen-dependent ZIP9 signaling pathways, inducing decreases in cAMP production and elevating intracellular free zinc levels, while (+)-catechin typically lacked these actions. Both (-)-epicatechin and (+)-catechin also bound to cell membranes of MDA-MB-468 breast cancer cells (nAR-null, high ZIP9 expression). MDA-MB-468 cells showed similar apoptotic, cAMP, and free zinc signaling responses to (-)-epicatechin to those observed in PC3-ZIP9 cells, as well as antagonism by (+)-catechin of testosterone-induced apoptosis and modulation of cAMP and caspase-3 levels. Moreover, knockdown of ZIP9 expression in MDA-MB-468 cells with siRNA decreased specific [3H]-testosterone binding of both catechins and blocked the apoptotic and free zinc responses to testosterone and (-)-epicatechin. The results indicate (-)-epicatechin is a potent ZIP9 agonist in breast and prostate cancer cells.

Gorgonians Are Foundation Species on Sponge-Dominated Mesophotic Coral Reefs in the Caribbean

Foundation species (FS) regulate ecological processes within communities often facilitating biodiversity and habitat complexity. Typically FS are dominant structure-forming taxa; but less dominant taxa having disproportionate ecological impacts to the community can also be FS. Mesophotic coral ecosystems (MCEs) are deep coral reef (∼30–150 m) communities, often dominated by emergent sponges in the Caribbean Basin. Despite the potential competitive advantage of sponges on MCEs, gorgonians are also common constituents of these reefs. Data from the Bahamas demonstrate increased biodiversity and densities of sponges on mesophotic reefs with gorgonians relative to reefs without these species. Drawing upon fifteen years of field surveys at five sites in the Caribbean Basin we assessed in situ interactions between gorgonians and sponges to quantify outcomes consistent with competition (i.e., tissue necrosis and overgrowth). Gorgonians were effective competitors against a variety of sponges, and two allelochemicals produced by Ellisella elongata were mechanistically important in interactions with Agelas clathrodes. We also examined invertebrate recruitment patterns near gorgonians to assess their role in facilitating MCE biodiversity. Our results indicate that live gorgonians, Antillogorgia bipinnata and E. elongata, facilitate biodiverse recruitment into MCEs, indicating that this process is governed by more than passive hydrodynamics. Collectively, these data indicate that these gorgonians exhibit both positive and negative ecological interactions (i.e., facilitation and competition, respectively) with sponges, and other taxa. Thus, these gorgonians are FS of MCE communities within the Caribbean Basin that display several traits contributing to the ecological structure of these understudied communities.

Opportunistic bacteria with reduced genomes are effective competitors for organic nitrogen compounds in coastal dinoflagellate blooms

BackgroundPhytoplankton blooms are frequent events in coastal areas and increase the production of organic matter that initially shapes the growth of opportunistic heterotrophic bacteria. However, it is unclear how these opportunists are involved in the transformation of dissolved organic matter (DOM) when blooms occur and the subsequent impacts on biogeochemical cycles.ResultsWe used a combination of genomic, proteomic, and metabolomic approaches to study bacterial diversity, genome traits, and metabolic responses to assess the source and lability of DOM in a spring coastal bloom of Akashiwo sanguinea. We identified molecules that significantly increased during bloom development, predominantly belonging to amino acids, dipeptides, lipids, nucleotides, and nucleosides. The opportunistic members of the bacterial genera Polaribacter, Lentibacter, and Litoricola represented a significant proportion of the free-living and particle-associated bacterial assemblages during the stationary phase of the bloom. Polaribacter marinivivus, Lentibacter algarum, and Litoricola marina were isolated and their genomes exhibited streamlining characterized by small genome size and low GC content and non-coding densities, as well as a smaller number of transporters and peptidases compared to closely related species. However, the core proteomes identified house-keeping functions, such as various substrate transporters, peptidases, motility, chemotaxis, and antioxidants, in response to bloom-derived DOM. We observed a unique metabolic signature for the three species in the utilization of multiple dissolved organic nitrogen compounds. The metabolomic data showed that amino acids and dipeptides (such as isoleucine and proline) were preferentially taken up by P. marinivivus and L. algarum, whereas nucleotides and nucleosides (such as adenosine and purine) were preferentially selected by L. marina.ConclusionsThe results suggest that the enriched DOM in stationary phase of phytoplankton bloom is a result of ammonium depletion. This environment drives genomic streamlining of opportunistic bacteria to exploit their preferred nitrogen-containing compounds and maintain nutrient cycling.AaAvcKVFm8o1fAVgiwaNNFVideo abstract