Search

Although coral reef ecosystems across the globe are in decline due to climate change and other anthropogenic stressors, certain inshore reefs of the Upper Florida Keys reef tract have persisted, with some even thriving, under marginalized conditions. To better understand the molecular basis of the thermotolerance displayed by these corals, a laboratory-based temperature challenge experiment that also featured conspecifics from a more stress-susceptible offshore reef was conducted with the common Caribbean reef-builder Orbicella faveolata, and the proteomes of both the coral hosts and their endosymbiotic dinoflagellate communities were profiled in (1) controls, (2) corals that succumbed to high-temperature stress and bleached, and (3) those that instead acclimated to high temperatures ex situ. Proteomic signatures varied most significantly across temperatures, host genotypes, and Symbiodiniaceae assemblages, and the two eukaryotic compartments of this mutualism exhibited distinct proteomic responses to high temperatures. Both partners maintained high levels of molecular chaperones and other canonical (eukaryotic) stress response (CSR) proteins in all treatments (including controls). Instead, proteins involved in lipid trafficking, metabolism, and photosynthesis played greater roles in the holobionts’ high-temperature responses, and these energy mobilization processes may have sustained the elevated protein turnover rates associated with the constitutively active CSR.

Background Dimethylsulfoniopropionate (DMSP) is a small sulphur compound which is produced in prodigious amounts in the oceans and plays a pivotal role in the marine sulfur cycle. Until recently, DMSP was believed to be synthesized exclusively by photosynthetic organisms; however we now know that corals and specific bacteria can also produce this compound. Corals are major sources of DMSP, but the molecular basis for its biosynthesis is unknown in these organisms. Results Here we used salinity stress, which is known to trigger DMSP production in other organisms, in conjunction with transcriptomics to identify coral genes likely to be involved in DMSP biosynthesis. We focused specifically on both adults and juveniles of the coral Acropora millepora: after 24 h of exposure to hyposaline conditions, DMSP concentrations increased significantly by 2.6 fold in adult corals and 1.2 fold in juveniles. Concomitantly, candidate genes enabling each of the necessary steps leading to DMSP production were up-regulated. Conclusions The data presented strongly suggest that corals use an algal-like pathway to generate DMSP from methionine, and are able to rapidly change expression of the corresponding genes in response to environmental stress. However, our data also indicate that DMSP is unlikely to function primarily as an osmolyte in corals, instead potentially serving as a scavenger of ROS and as a molecular sink for excess methionine produced as a consequence of proteolysis and osmolyte catabolism in corals under hypo-osmotic conditions. Electronic supplementary material The online version of this article (doi:10.1186/s12864-017-3959-0) contains supplementary material, which is available to authorized users.

Given the threat posed by population outbreaks of Acanthaster planci to coral reefs throughout the Indo-Pacific, significant investment is being made to reduce the number of sea stars and their effects on coral assemblages, both through ongoing direct control programs and indirectly, through targeted improvements in water quality and fisheries management. In Australia, bile salts have recently replaced sodium bisulfate as the chemical used to inject, and thereby quickly and efficiently kill, individual sea stars. This study reports on results of experimental studies conducted prior operationalizing bile salts for widespread use on Australia's Great Barrier Reef, both to optimize doses of bile salts and further examine potential side-effects of administering low doses of bile salts into individual sea stars when found at high concentrations. This study showed that injecting A. planci with 10 mL of 8 g l−1 Bile Salts No. 3 or 12 g l−1 of Oxgall solution into the base of the arm with a new gun adapted with a 16 Gauge x1/2” needle is the most rapid and effective way to kill individual A. planci, which were up to 42 cm in diameter. No immediate flow-on effects on reef fish, corals, and other benthic invertebrates were observed in laboratory experiments and field surveys. Efficient control measures using bile derivatives can offer immediate relief from ongoing COTS predation, and when done in conjunction with improved land use practices that reduce nutrient input and establishment of protected areas to protect predator species, can offer benefits for the resilience of reef ecosystems.

The reproductive biology of Ophiocoma aethiops and O. alexandri was analyzed based on monthly time-series samples from May 2009 to April 2010 at Estacahuite Bay, Oaxaca, in the Mexican tropical Pacific Ocean. We evaluated the relationship between the reproductive biology of both species and variations of sea-bottom temperature, salinity, pluvial precipitation, photoperiod (light hours) and chlorophyll. Sex ratio, gonadosomatic index (GSI), actual fecundity and oocyte size were determined. Monthly variations of the environmental factors were compared with variations of GSI. Both species are gonochoric ophiuroids and the ratio of males to females (1:1) was not significantly different throughout the year. There were significant differences in GSI values between the 2 species, but temporal variation patterns were similar. Gametogenesis showed synchrony among males and females and 4 stages were recognized for both sexes. Spawning occurred in females of O. aethiops from May to November and from April to December in O. alexandri. Main spawning for males of both species occurred from May to December, although there was always availability of mature spermatozoa. Mean oocyte size was 32 to 58 µm for O. alexandri and 47 to 63 µm for O. aethiops. Mean ± SD fecundity was 3.03 ± 1.72 million vitel- logenic oocytes per female for O. aethiops and 1.61 ± 0.99 million for O. alexandri. The reproduc- tive patterns of O. aethiops and O. alexandri are influenced by the local oceanic dynamics, as has been reported for other echinoderm species in the area, but they also have a high genetic (endo - genous) element, because the observed patterns resemble those determined for the Panamian populations of these 2 species.

The family Melithaeidae (Octocorallia: Alcyonacea) is distributed in the West Pacific, Indian Ocean and the Red Sea. They are most abundant in warmer waters but can also be found in temperate waters. At present six genera are assigned to this family (Melithaea, Mopsella, Clathraria, Acabaria, Wrightella and Asperaxis), however overlapping characteristics make this group's taxonomic identification difficult and their relationships unclear. There are only a few reports from the Ryukyu Archipelago in southern Japan of melithaeids and most other octocorals, despite the islands being an area of high octocoral diversity. To help resolve the taxonomic confusion in this family, samples from various Ryukyu Archipelago locations were collected and DNA sequences of nuclear 28S ribosomal DNA and mitochondrial cytochrome oxidase I (COI) were obtained. Additionally, SEM micrographs of the sclerites of specimens were taken to further confirm the molecular results. Three strongly supported clades were recovered from the COI and 28S rDNA analyses, corresponding to Melithaea, Acabaria, and Mopsella, and in most cases clades were clearly related with the sclerite shape reported for each genus. These results show clearly that molecular differences are present between the three genera, and also demonstrates the strong need of other molecular markers for resolving intra-generic phylogenies. Our results provide baseline data for future studies of this octocoral family, not only on taxonomy, but also with regards to their distribution in the Ryukyu Islands.

In this study the effect of refrigeration, abusive and optimum growth temperatures (5, 20, and 37C) on the dynamic of bacterial populations in pure and co-cultures was investigated. The antagonistic activity of two lactic acid bacteria (LAB) strains, with auto- and co-inducible bacteriocin-like inhibitory substance production, against Escherichia coli and Listeria monocytogenes was described and quantified through the comparison of the growth curves and the estimated kinetic parameters of pure and mixed cultures. The growth pattern of the bacterial binary systems studied showed that the mechanism of inhibition was complex and not attributable to one antagonist factor. Temperature had an effect on the spectrum of action and the level of inhibition of the growth of the pathogens by LAB. Low and suboptimal temperatures significantly reduced the antagonistic activity of the two LAB strains against the pathogenic bacteria. At refrigeration temperature only the growth of L. monocytogenes was inhibited by Lactobacillus plantarum WS4174. The results obtained show the importance of validating functionality of biological antimicrobial systems when used for biopreservation purposes under different application conditions. PRACTICAL APPLICATIONS Consumers demand the use of natural systems to provide safety foods with extended shelf life. Lactic acid bacteria (LAB) have demonstrated through thousands years their potential to control spoilage and pathogenic microorganisms and therefore suitable for biopreservation purposes. The antagonistic properties of LAB rely on the production of organic acids and antimicrobial peptides (bacteriocins) among other bioactive metabolites. However, there is need for more research in order to understand the mechanism of inhibition and to assess the effectiveness of LAB and/or of their growth-limiting metabolites under different conditions. LAB and their antimicrobial compounds, such as bacteriocins, are not necessarily functional in all food systems and environmental conditions. The present study shows how the fluctuation in bacteriocin-like inhibitory substances production and/or activity caused by temperature changes is reflected on the inhibition potential against Listeria monocytogenes and Escherichia coli. Effectiveness of biological control is essential for its safe and successful application on foods.

Previously, it has been found that species of the zoanthid genus Zoanthus (Cnidaria: Hexacorallia) possess high levels of intrageneric ITS-rDNA sequence variation both between congeners and also within one species, Zoanthus sansibaricus, resulting in an uncertain internal transcribed spacer of ribosomal DNA (ITS-rDNA) phylogeny for this group. For the first time, the secondary structures of the internal transcribed spacer 2 (ITS 2) sequences were analyzed in an attempt to further clarify and solve relationships within Zoanthus, and also with the closely related genera Acrozoanthus and Isaurus (all in family Zoanthidae). Results show that most species’ ITS2 secondary structures follow the basic four-helix-ring model proposed for most eukaryotes including anthozoans. However, not all structures had the conserved motifs present in scleractinian corals, and Z. sansibaricus had two different structural conformations from the two different ITS2 types present. The ITS2 secondary structures of Zoanthus in this study, present a well resolved and supported phylogeny that makes it an appropriate tool for solving phylogenies in this taxonomic group. Based on ITS2 secondary structure results here, we theorize that: (1) Acrozoanthus is a valid monophyly separate from Zoanthus; (2) Z. gigantus, Z. sansibaricus, and Z. praelongus do not have any compensatory base changes (CBCs) between them and form a related clade distinct from the more divergent Z. kuroshio/Z. vietnamensis clade. The results furthermore suggest that the presence of CBCs may exist only at much lower ratios between different species in zoanthids than in other investigated organism lineages.

Gorgoniid octocorals taxonomy (Cnidaria; Octocorallia; Gorgoniidae) includes diagnostic characters not well defined at the generic level, and based on the family diagnosis some species could be classified in either Gorgoniidae or Plexauridae. In this study, we used sequences from the Internal Transcribed Spacer 2 (ITS2) and their predicted RNA secondary structure to both correct the alignment and reconstruct phylogenies using molecular morphometrics for 24 octocorals mostly from the Atlantic. ITS2 exhibited the six-helicoidal ring-model structure found in eukaryotes, and provided 38 parsimony-informative characters. The proposed phylogenies, though differing between sequence- and structure-base results, provided consistent support for several clades. Genera considered part of the polyphyletic genus Leptogorgia, such as Filigorgia, were distantly related to the former in all phylogenetic hypotheses. Main differences among the hypotheses consisted in the placement of Muriceopsis (previously considered from the Plexauridae family) and Filigorgia. Excluding Muriceopsis and an undescribed octocoral from Tobago, Plexaurella and Pterogorgia grouped together as a sister branch of Pinnigorgia spp. but long-branch attraction was evident for the grouping of Plexaurella nutans (another plexaurid) and Pterogorgia citrina. Unexpected results were the divergence between Caribbean genera, Gorgonia and Pseudopterogorgia, which were placed basal respect to Pacifigorgia and Leptogorgia (=Lophogorgia). ITS2 provided support to corroborate observations based on sclerite morphology: species with "capstan sclerites" (e.g., Pacifigorgia and Leptogorgia) were characterized by a long helix IV with one internal loop and a helix V with four internal loops; "scaphoid sclerites" had a predominantly long helix V if compared to helix IV; "asymmetric spiny sclerites" (Muriceopsis, Pinnigorgia and the undescribed octocoral) exhibited one or two lateral bulges in the V helix. Remarkably, Muriceopsis and Pinnigorgia were supported by a complete Compensatory Base Change (CBC) (A-U to G-C) in helix V. Filigorgia with simple "spindles" had a short helix IV and a large central ring. DNA sequences from the nuclear ITS2 region, including information from predicted RNA secondary structure, despite their reduced length, provided numerous characters and phylogenetic information among Gorgoniidae genera and species.

Fuente TESIUNAM

Tesis de Maestría

The current work studied four types of binary antagonist/pathogen bacterial culture system, in order to determine the effect of interaction between two strains ofLactobacillus plantarumand two food-borne pathogens,Listeria monocytogenesandEscherichia coli, in whole UHT milk at 37°C. To determine the type of interaction between the two bacterial populations in co-cultures and to evaluate the antagonistic activity of the lactic acid bacteria (LAB) on the pathogenic bacteria, the growth curves, the kinetic parameters, and the pH profiles of mono- and co-cultures were compared. TheLb. plantarumstrains showed different bacteriocin-like inhibitory substance (BLIS) production, auto- and co-inducible. The antibacterial effect of neutralized supernatants of mono and co-cultures harvested at different times of incubation was assessed in order to establish the presence of bacteriocin-like inhibitory-substances (BLIS) and their possible relation to the growth inhibition of the pathogen. The LAB reduced the growth ofEsch. coliand ofList. monocytogenesby 4 and ∼5 log cycles, respectively and influenced other growth kinetic parameters, such as μmaxand lag phase, in the different binary combinations. The growth of the LAB was not relevantly altered by simultaneous growth with the pathogenic strains showing an interaction of amensalism. The pattern of inhibition exerted by the LAB on the pathogens was different;Lb. plantarumLB279 inhibited the growth ofList. monocytogenesmore effectively than that ofEsch. coli. The behaviour ofEsch. coliin co-culture withLb. plantarumWS4174 suggested the presence of metabolic crowding in the mechanism of growth suppression. This exploratory study showed the complexity and specific particularities of the inhibition phenomena between bacterial communities.

Background Most phylogenetic studies using current methods have focused on primary DNA sequence information. However, RNA secondary structures are particularly useful in systematics because they include characteristics, not found in the primary sequence, that give "morphological" information. Despite the number of recent molecular studies on octocorals, there is no consensus opinion about a region that carries enough phylogenetic resolution to solve intrageneric or close species relationships. Moreover, intrageneric morphological information by itself does not always produce accurate phylogenies; intra-species comparisons can reveal greater differences than intra-generic ones. The search for new phylogenetic approaches, such as by RNA secondary structure analysis, is therefore a priority in octocoral research. Results Initially, twelve predicted RNA secondary structures were reconstructed to provide the basic information for phylogenetic analyses; they accorded with the 6 helicoidal ring model, also present in other groups of corals and eukaryotes. We obtained three similar topologies for nine species of the Caribbean gorgonian genus Eunicea (candelabrum corals) with two sister taxa as outgroups (genera Plexaura and Pseudoplexaura) on the basis of molecular morphometrics of ITS2 RNA secondary structures only, traditional primary sequence analyses and maximum likelihood, and a Bayesian analysis of the combined data. The latter approach allowed us to include both primary sequence and RNA molecular morphometrics; each data partition was allowed to have a different evolution rate. In addition, each helix was partitioned as if it had evolved at a distinct rate. Plexaura flexuosa was found to group within Eunicea; this was best supported by both the molecular morphometrics and combined analyses. We suggest Eunicea flexuosa (Lamouroux, 1821) comb. nov., and we present a new species description including Scanning Electron Microscopy (SEM) images of morphological characteristics (sclerites). Eunicea flexuosa, E. pallida, E. laxispica and E. mammosa formed a separate clade in the molecular phylogenies, and were reciprocally monophyletic with respect to other Eunicea (Euniceopsis subgenus, e.g. E. tourneforti and E. laciniata) in the molecular morphometrics tree, with the exception of E. fusca. Moreover, we suggest a new diagnostic character for Eunicea, also present in E. flexuosa: middle layer sclerites > 1 mm in length. Conclusion ITS2 was a reliable sequence for intrageneric studies in gorgonian octocorals because of the amount of phylogenetic signal, and was corroborated against morphological characters separating Eunicea from Plexaura. The ITS2 RNA secondary structure approach to phylogeny presented here did not rely on alignment methods such as INDELS, but provided clearly homologous characters for partition analysis and RNA molecular morphometrics. These approaches support the divergence of Eunicea flexuosa comb. nov. from the outgroup Plexaura, although it has been considered part of this outgroup for nearly two centuries because of morphological resemblance.

Background Silicone has been the standard material for indwelling devices to date. Polyurethane II exhibits properties that makes it suitable as a component of long-indwelling vascular access, with the added advantage of low cost. Objective To describe the experience of an intravenous therapy team with 206 polyurethane II catheters used as long-indwelling vascular access in patients with cancer. Materials and methods All polyurethane II single- and double-lumen catheters implanted between January 1, 1994, and March 15, 1995, were analyzed, including time of stay and type and rate of infectious and noninfectious complications. Results A total of 206 catheters were placed—164 single-lumen and 42 double-lumen catheters—in 190 patients; average stay was 101 days (range, 1-445 days). The infection incidence rate was 0.66 per 1000 catheter-days for single-lumen catheters and 1.6 per 1000 catheter-days for double-lumen catheters. Noninfectious complications included 1 thrombosis (incidence rate, 0.06 per 1000 catheter-days for single-lumen and none for double-lumen catheters), 5 catheter ruptures (2.4%), and 1 pneumothorax (0.48%). Twelve catheters (8.3%) were removed because of complications; only 1 was infectious. The remaining 17 infectious episodes (94.4%) were resolved without catheter removal. Our complication rate with single-lumen catheters in this series was similar to our previous experience with a nontunneled silicone catheter. Conclusions Our findings indicate that polyurethane II catheters have proven useful and safe as long-indwelling vascular access in patients with cancer at our hospital at a considerably lower cost.

Background Colonial invertebrates such as corals exhibit nested levels of modularity, imposing a challenge to the depiction of their morphological evolution. Comparisons among diverse Caribbean gorgonian corals suggest decoupling of evolution at the polyp vs. branch/internode levels. Thus, evolutionary change in polyp form or size (the colonial module sensu stricto) does not imply a change in colony form (constructed of modular branches and other emergent features). This study examined the patterns of morphological integration at the intraspecific level. Pseudopterogorgia bipinnata (Verrill) (Octocorallia: Gorgoniidae) is a Caribbean shallow water gorgonian that can colonize most reef habitats (shallow/exposed vs. deep/protected; 1–45 m) and shows great morphological variation. Results To characterize the genotype/environment relationship and phenotypic plasticity in P. bipinnata, two microsatellite loci, mitochondrial (MSH1) and nuclear (ITS) DNA sequences, and (ITS2) DGGE banding patterns were initially compared among the populations present in the coral reefs of Belize (Carrie Bow Cay), Panama (Bocas del Toro), Colombia (Cartagena) and the Bahamas (San Salvador). Despite the large and discrete differentiation of morphotypes, there was no concordant genetic variation (DGGE banding patterns) in the ITS2 genotypes from Belize, Panama and Colombia. ITS1–5.8S-ITS2 phylogenetic analysis afforded evidence for considering the species P. kallos (Bielschowsky) as the shallow-most morphotype of P. bipinnata from exposed environments. The population from Carrie Bow Cay, Belize (1–45 m) was examined to determine the phenotypic integration of modular features such as branch thickness, polyp aperture, inter-polyp distance, internode length and branch length. Third-order partial correlation coefficients suggested significant integration between polypar and colonial traits. Some features did not change at all despite 10-fold differences in other integrated features. More importantly, some colonial features showed dependence on modular features. Conclusion Consequently, module integration in gorgonian corals can be shifted, switched or canalized along lineages. Modular marine organisms such as corals are variations on a single theme: their modules can couple or decouple, allowing them to adapt to all marine benthic environments.