Dual Species Research Articles

Effect of Schistosomiasis and Soil-Transmitted Helminth Infections on Physical Fitness of School Children in Côte d'Ivoire

BackgroundSchistosomiasis and soil-transmitted helminthiasis are important public health problems in sub-Saharan Africa causing malnutrition, anemia, and retardation of physical and cognitive development. However, the effect of these diseases on physical fitness remains to be determined.MethodologyWe investigated the relationship between schistosomiasis, soil-transmitted helminthiasis and physical performance of children, controlling for potential confounding of Plasmodium spp. infections and environmental parameters (i.e., ambient air temperature and humidity). A cross-sectional survey was carried out among 156 school children aged 7–15 years from Côte d'Ivoire. Each child had two stool and two urine samples examined for helminth eggs by microscopy. Additionally, children underwent a clinical examination, were tested for Plasmodium spp. infection with a rapid diagnostic test, and performed a maximal multistage 20 m shuttle run test to assess their maximal oxygen uptake (VO2 max) as a proxy for physical fitness.Principal FindingsThe prevalence of Schistosoma haematobium, Plasmodium spp., Schistosoma mansoni, hookworm and Ascaris lumbricoides infections was 85.3%, 71.2%, 53.8%, 13.5% and 1.3%, respectively. Children with single, dual, triple, quadruple and quintuple species infections showed VO2 max of 52.7, 53.1, 52.2, 52.6 and 55.6 ml kg−1 min−1, respectively. The VO2 max of children with no parasite infections was 53.5 ml kg−1 min−1. No statistically significant difference was detected between any groups. Multivariable analysis revealed that VO2 max was influenced by sex (reference: female, coef. = 4.02, p<0.001) and age (years, coef. = −1.23, p<0.001), but not by helminth infection and intensity, Plasmodium spp. infection, and environmental parameters.Conclusion/SignificanceSchool-aged children in Côte d'Ivoire showed good physical fitness, irrespective of their helminth infection status. Future studies on children's physical fitness in settings where helminthiasis and malaria co-exist should include pre- and post-intervention evaluations and the measurement of hemoglobin and hematocrit levels and nutritional parameters as potential co-factors to determine whether interventions further improve upon fitness.

The effects of glutaraldehyde on the control of single and dual biofilms of Bacillus cereus and Pseudomonas fluorescens

Glutaraldehyde (GLUT) was evaluated for control of single and dual species biofilms of Bacillus cereus and Pseudomonas fluorescens on stainless steel surfaces using a chemostat system. The biofilms were characterized in terms of mass, cell density, total and matrix proteins and polysaccharides. The control action of GLUT was assessed in terms of inactivation and removal of biofilm. Post-biocide action was characterized 3, 7, 12, 24, 48 and 72 h after treatment. Tests with planktonic cells were also performed for comparison. The results demonstrated that in dual species biofilms the metabolic activity, cell density and the content of matrix proteins were higher than those of either single species. Planktonic B. cereus was more susceptible to GLUT than P. fluorescens. The biocide susceptibility of dual species planktonic cultures was an average of each single species. Planktonic cells were more susceptible to GLUT than their biofilm counterparts. Biofilm inactivation was similar for both of the single biofilms while dual biofilms were more resistant than single species biofilms. GLUT at 200 mg l−1 caused low biofilm removal (<10%). Analysis of the post-biocide treatment data revealed the ability of biofilms to recover their activity over time. However, 12 h after biocide application, sloughing events were detected for both single and dual species biofilms, but were more marked for those formed by P. fluorescens (removal >40% of the total biofilm). The overall results suggest that GLUT exerts significant antimicrobial activity against planktonic bacteria and a partial and reversible activity against B. cereus and P. fluorescens single and dual species biofilms. The biocide had low antifouling effects when analysed immediately after treatment. However, GLUT had significant long-term effects on biofilm removal, inducing significant sloughing events (recovery in terms of mass 72 h after treatment for single biofilms and 42 h later for dual biofilms). In general, dual species biofilms demonstrated higher resistance and resilience to GLUT exposure than either of the single species biofilms. P. fluorescens biofilms were more susceptible to the biocide than B. cereus biofilms.

Selective killing of Aggregatibacter actinomycetemcomitans by ciprofloxacin during development of a dual species biofilm with Streptococcus sanguinis

ObjectivesPeriodontal disease is associated with a pathogen-induced transition to a chronic destructive inflammatory response. Since commensals may either passively or actively contribute to immune homeostasis, therapies aimed at selectively reducing the competitive advantage of pathogens may be effective supplements to traditional methods. We developed an in vitro system to grow biofilms composed of the pathogen (Aggregatibacter actinomycetemcomitans) and the commensal (Streptococcus sanguinis). We used the biofilm model to determine the feasibility of selectively killing the pathogen using the fluoroquinolone, ciprofloxacin. DesignBiofilms were exposed to relevant ciprofloxacin doses during the first 24h of development, with subsequent removal of the ciprofloxacin for a 24h period. Biofilm growth was assessed by confocal laser scanning microscopy, crystal violet staining and DNA abundance. ResultsExposure to 0.01mg/L or 0.5mg/L ciprofloxacin significantly reduced the microcolony size and cell surface density of A. actinomycetemcomitans in the dual species biofilm over a 24h period whilst allowing uninhibited S. sanguinis biofilm formation. A. actinomycetemcomitans biofilm development was insignificant over a subsequent 24h period after removal of the ciprofloxacin indicating that A. actinomycetemcomitans cells were killed. ConclusionsA. actinomycetemcomitans residing in a dual species biofilm with the commensal, S. sanguinis can be selectively killed, or at least rendered metabolically inactive, by treatment with ciprofloxacin. The dual species biofilm model will be a useful tool for designing in vivo studies to determine the efficacy of selective killing agents as an adjunct treatment of localized aggressive forms of periodontal disease.

Effects of Dual Microalgal Species Biofilms on New Zealand Black-Footed Abalone (Hailotis iris) Larval/Post-Larval Processes

Dual microalgal species biofilms with distinct amino acid characteristics were tested for their effects on abalone (Haliotis iris) initial attachment, metamorphosis, settlement, and survival. Nine microalgal species, isolated from around Auckland, New Zealand, were grown in the laboratory, and used to produce nine dual microalgal species biofilms. Abalone larvae were exposed to the different biofilm treatments and controls (no biofilms) for seven (attachment and metamorphosis) and 14 (settlement and survival) days. The larvae performed significantly better in the dual microalgal biofilms compared to controls, and some biofilms resulted in better attachment, metamorphosis, settlement, and survival than others. For example, the best-performing biofilms almost always contained cyanobacteria (Oscillatoria cf. erythrata, Anacystis cf. aeruginosa, and Schizothrix cf. calcicola), which are attributed with better nutritional values. However, the amino acid profiles did not produce a clear pattern with regard to their effects on the four larval processes. Instead, total amino acid (TAA) content was positively correlated with percentage of attachment and metamorphosis. Greater TAA contents are likely to reflect greater amounts of extra-cellular polymers within the biofilms, which are suggested to improve larval performance.

Community signalling between Streptococcus gordonii and Porphyromonas gingivalis is controlled by the transcriptional regulator CdhR

Interspecies signalling between Porphyromonas gingivalis and Streptococcus gordonii serves to constrain development of dual species communities. Contact with S. gordonii propagates a tyrosine phosphorylation-dependent signal within P. gingivalis that culminates in reduced transcription of adhesin and signalling genes. Here we demonstrate the involvement of the P. gingivalis orphan LuxR family transcription factor PGN_1373, which we designate CdhR, in this control pathway. Expression of cdhR is elevated following contact with S. gordonii; however, regulation of cdhR did not occur in a mutant lacking the tyrosine phosphatase Ltp1, indicating that CdhR and Ltp1 are components of the same regulon. Contact between S. gordonii and a CdhR mutant resulted in increased transcription of mfa, encoding the subunit of the short fimbriae, along with higher levels of Mfa protein. Expression of luxS, encoding AI-2 synthase, was also increased in the cdhR mutant after contact with S. gordonii. The Mfa adhesive function and AI-2-dependent signalling participate in the formation and development of dual species communities, and consistent with this the cdhR mutant displayed elevated accumulation on a substratum of S. gordonii. Recombinant CdhR protein bound to upstream regulatory regions of both mfa and luxS, indicating that CdhR has a direct effect on gene expression. LuxS was also found to participate in a positive feedback loop that suppresses CdhR expression. Interaction of Mfa fimbriae with S. gordonii is necessary to initiate signalling through CdhR. These results reveal CdhR to be an effector molecule in a negative regulatory network that controls P. gingivalis-S. gordonii heterotypic communities.

Effects of Lactobacillus rhamnosus GG on saliva-derived microcosms

Objective The probiotic strain Lactobacillus rhamnosus GG (LGG) is shown to hamper the presence of mutans streptococci in saliva and may have positive effects on oral health. We investigated the effects of LGG on the cariogenic potential and microbial composition of saliva-derived microcosms. Design Single and dual species biofilms of LGG and Streptococcus mutans, and saliva-derived microcosms with or without LGG were grown in an Active Attachment Biofilm model. The microcosms were grown on bovine dentin/enamel discs in the presence or absence of sucrose (suc+/suc−). The presence of LGG was determined by multiplex ligation-dependent probe amplification (MLPA) and real-time PCR. Mutans streptococci (MS) and total viable counts, pH of the spent medium, capacity of lactate formation and integrated mineral loss in dentin was assessed. MLPA was used for identification and relative quantification of 20 oral microorganisms in the microcosms. Principal Component Analysis was applied to MLPA data. Results LGG inhibited the growth of S. mutans in dual species biofilms and did not affect the pH. LGG established in saliva-derived microcosms and reduced MS counts significantly, but did not affect pH or dentin demineralization. Simultaneous growth of the microcosms with LGG under heavy cariogenic conditions (suc+) introduced a compositional shift in the microbial community. The CFU, real-time PCR and MLPA data correlated significantly. Conclusion We conclude that LGG established into and inhibited the growth of MS in complex saliva-derived biofilms, but this had no significant effect on cariogenic potential of the microcosms. This suggests that other microorganisms besides MS were responsible for increased cariogenicity of sucrose-exposed biofilms.

Selective substitution of amino acids limits proteolytic cleavage and improves the bioactivity of an anti-biofilm peptide that targets the periodontal pathogen, Porphyromonas gingivalis

The interaction of the periodontal pathogen, Porphyromonas gingivalis, with oral streptococci such as Streptococcus gordonii precedes colonization of the subgingival pocket and represents a target for limiting P. gingivalis colonization of the oral cavity. Previous studies showed that a synthetic peptide (designated BAR) derived from the antigen I/II protein of S. gordonii was a potent competitive inhibitor of P. gingivalis adherence to S. gordonii and subsequent biofilm formation. Here we show that despite its inhibitory activity, BAR is rapidly degraded by intact P. gingivalis cells in vitro. However, in the presence of soluble Mfa protein, the P. gingivalis receptor for BAR, the peptide is protected from proteolytic degradation suggesting that the affinity of BAR for Mfa is higher than for P. gingivalis proteases. The rate of BAR degradation was reduced when the P. gingivalis lysine-specific gingipain was inhibited using the specific protease inhibitor, z-FKcK, or when the gene encoding the Lys-gingipain was inactivated. In addition, substituting d-Lys for l-Lys residues in BAR prevented degradation of the peptide when incubated with the Lys-gingipain and increased its specific adherence inhibitory activity in a S. gordonii– P. gingivalis dual species biofilm model. These results suggest that Lys-gingipain accounts in large part for P. gingivalis-mediated degradation of BAR and that more effective peptide inhibitors of P. gingivalis adherence to streptococci can be produced by introducing modifications that limit the susceptibility of BAR to the Lys-gingipain and other P. gingivalis associated proteases.

Phage control of dual species biofilms of Pseudomonas fluorescens and Staphylococcus lentus

Despite the recent enthusiasm for using bacteriophages as bacterial control agents, there are only limited studies concerning phage interaction with their respective hosts residing in mixed biofilm consortia and especially in biofilms where the host species is a minor constituent. In the present work, a study was made of mono and dual species biofilms formed by Pseudomonas fluorescens (Gram-negative) and/or Staphylococcus lentus (Gram-positive) and their fate after infection with phages. The dual species biofilms consisted predominantly of S. lentus. The exposure of these biofilms to a cocktail containing both P. fluorescens and S. lentus phages effectively killed and removed the hosts from the substratum. Additionally, this cocktail approach also controlled the hosts released from the biofilms to the planktonic phase. The ability of phages to control a host population present in minority in the mixed species biofilm was also assessed. For this objective, the biofilms were challenged only with phage φIBB-PF7A, specific for P. fluorescens and the results obtained were to some extent unpredicted. First, φIBB-PF7A readily reached the target host and caused a significant population decrease. Secondly, and surprisingly, this phage was also capable of causing partial damage to the biofilms leading to the release of the non-susceptible host (S. lentus) from the dual species biofilms to the planktonic phase. The efficiency of phage treatment of biofilms was to some extent dependent on the number of cells present and also conditioned by the infection strategy (dynamic or static) utilized in the infection of the biofilms. Nevertheless, in most circumstances phages were well capable of controlling their target hosts.

Pseudomonas aeruginosa inhibits in-vitro Candida biofilm development

BackgroundElucidation of the communal behavior of microbes in mixed species biofilms may have a major impact on understanding infectious diseases and for the therapeutics. Although, the structure and the properties of monospecies biofilms and their role in disease have been extensively studied during the last decade, the interactions within mixed biofilms consisting of bacteria and fungi such as Candida spp. have not been illustrated in depth. Hence, the aim of this study was to evaluate the interspecies interactions of Pseudomonas aeruginosa and six different species of Candida comprising C. albicans, C. glabrata, C. krusei, C. tropicalis, C. parapsilosis, and C. dubliniensis in dual species biofilm development.ResultsA significant reduction in colony forming units (CFU) of C. parapsilosis (90 min), C. albicans and C. tropicalis (90 min, 24 h and 48 h), C. dubliniensis and C. glabrata, (24 h and 48 h) was noted when co-cultured with P. aeruginosa in comparison to their monospecies counterparts (P < 0.05). A simultaneous significant reduction in P. aeruginosa numbers grown with C. albicans (90 min and 48 h), C. krusei (90 min, 24 h and 48 h),C. glabrata, (24 h and 48 h), and an elevation of P. aeruginosa numbers co-cultured with C. tropicalis (48 h) was noted (P < 0.05). When data from all Candida spp. and P. aeruginosa were pooled, highly significant mutual inhibition of biofilm formation was noted (Candida P < 0.001, P. aeruginosa P < 0.01). Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM) analyses confirmed scanty architecture in dual species biofilm in spite of dense colonization in monospecies counterparts.ConclusionsP. aeruginosa and Candida in a dual species environment mutually suppress biofilm development, both quantitatively and qualitatively. These findings provide a foundation to clarify the molecular basis of bacterial-fungal interactions, and to understand the pathobiology of mixed bacterial-fungal infections.

Existence of dual species composed of Cu+ in CuMFI being bridged by C2H2

The interaction of ethyne (C(2)H(2)), as well as of carbon dioxide (CO(2)), with copper-ion-exchanged MFI zeolite (CuMFI) at room temperature was examined. It was found that CuMFI preferentially adsorbs C(2)H(2), while this material does not respond to CO(2). To clarify the specificity of CuMFI, a combination of various experimental techniques and theoretical calculations was adopted. Distinctive interaction energies of 140 and 110 kJ mol(-1) were clearly observed at the initial stage of C(2)H(2) adsorption on CuMFI, suggesting the presence of two types of adsorbed C(2)H(2). Two distinct IR bands at 1620 and 1814 cm(-1) appeared, which were assigned to the C[triple bond]C stretching vibration modes of C(2)H(2) differing in their adsorbed state. Both photoluminescence and X-ray absorption spectra showed that cuprous ions (Cu(+)) in CuMFI act as efficient sites for a marked C(2)H(2) adsorption. From the analysis of the latter spectra and the calculational results based on the density functional theory, the formation of dual Cu(+)...(C(2)H(2))...Cu(+) complexes was indicated for the first time for CuMFI, and such a special configuration of the Cu(+) sites contributed to the extremely strong adsorption of C(2)H(2). In contrast, it was necessary for the linear CO(2) molecule to take a bent structure to be adsorbed on Cu(+) in CuMFI. It was concluded that the difference in the adsorption response of Cu(+) in CuMFI towards C(2)H(2) and CO(2) is due to the chemistry between the nature of electron donation of Cu(+) and the hybrid orbitals of the respective molecules. This work promotes further understanding of the states of active centres in CuMFI for C(2)H(2) activation, as well as for N(2) fixation.

A modeling and simulation study of siderophore mediated antagonism in dual-species biofilms.

BackgroundSeveral bacterial species possess chelation mechanisms that allow them to scavenge iron from the environment under conditions of limitation. To this end they produce siderophores that bind the iron and make it available to the cells later on, while rendering it unavailable to other organisms. The phenomenon of siderophore mediated antagonism has been studied to some extent for suspended populations where it was found that the chelation ability provides a growth advantage over species that do not have this possibility. However, most bacteria live in biofilm communities. In particular Pseudomonas fluorescens and Pseudomonas putida, the species that have been used in most experimental studies of the phenomenon, are known to be prolific biofilm formers, but only very few experimental studies of iron chelation have been published to date for the biofilm setting. We address this question in the present study.MethodsBased on a previously introduced model of iron chelation and an existing model of biofilm growth we formulate a model for iron chelation and competition in dual species biofilms. This leads to a highly nonlinear system of partial differential equations which is studied in computer simulation experiments.Conclusions(i) Siderophore production can give a growth advantage also in the biofilm setting, (ii) diffusion facilitates and emphasizes this growth advantage, (iii) the magnitude of the growth advantage can also depend on the initial inoculation of the substratum, (iv) a new mass transfer boundary condition was derived that allows to a priori control the expect the expected average thickness of the biofilm in terms of the model parameters.

Competition Triggers Plasmid-Mediated Enhancement of Substrate Utilisation in Pseudomonas putida

Competition between species plays a central role in the activity and structure of communities. Stable co-existence of diverse organisms in communities is thought to be fostered by individual tradeoffs and optimization of competitive strategies along resource gradients. Outside the laboratory, microbes exist as multispecies consortia, continuously interacting with one another and the environment. Survival and proliferation of a particular species is governed by its competitive fitness. Therefore, bacteria must be able to continuously sense their immediate environs for presence of competitors and prevailing conditions. Here we present results of our investigations on a novel competition sensing mechanism in the rhizosphere-inhabiting Pseudomonas putida KT2440, harbouring gfpmut3b-modified KanR TOL plasmid. We monitored benzyl alcohol (BA) degradation rate, along with GFP expression profiling in mono species and dual species cultures. Interestingly, enhanced plasmid expression (monitored using GFP expression) and consequent BA degradation were observed in dual species consortia, irrespective of whether the competitor was a BA degrader (Pseudomonas aeruginosa) or a non-degrader (E. coli). Attempts at elucidation of the mechanistic aspects of induction indicated the role of physical interaction, but not of any diffusible compounds emanating from the competitors. This contention is supported by the observation that greater induction took place in presence of increasing number of competitors. Inert microspheres mimicking competitor cell size and concentration did not elicit any significant induction, further suggesting the role of physical cell-cell interaction. Furthermore, it was also established that cell wall compromised competitor had minimal induction capability. We conclude that P. putida harbouring pWW0 experience a competitive stress when grown as dual-species consortium, irrespective of the counterpart being BA degrader or not. The immediate effect of this stress is a marked increase in expression of TOL, leading to rapid utilization of the available carbon source and massive increase in its population density. The plausible mechanisms behind the phenomenon are hypothesised and practical implications are indicated and discussed.

Emission Enhancement through Dual Donor Sensitization: Modulation of Structural and Spectroscopic Properties in a Series of Europium Tetracyanoplatinates

The synthesis of three different europium tetracyanoplatinates all incorporating 2,2':6',2''-terpyridine (terpy) have been carried out in acetonitrile/water mixtures by reaction of Eu(3+) salts with terpy and potassium tetracyanoplatinate. The use of different Eu(3+) sources results in the isolation of Eu(C(15)H(11)N(3))(H(2)O)(2)(NO(3))(Pt(CN)(4)) x CH(3)CN (1), {Eu(C(15)H(11)N(3))(H(2)O)(3)}(2)(Pt(CN)(4))(3) x 2 H(2)O (2), or [Eu(C(15)H(11)N(3))(H(2)O)(2)(CH(3)COO)(2)](2)Pt(CN)(4) x 3 H(2)O (3) for the nitrate, triflate, or acetate salts, respectively. All three compounds have been prepared as colorless crystals, and single-crystal X-ray diffraction has been used to investigate their structural features. Crystallographic data (MoK alpha, lambda = 0.71073 A, T = 290 K): 1, monoclinic, space group P2(1)/c, a = 12.835(1), b = 15.239(1), c = 13.751(2) A, beta = 105.594(9) degrees, V = 2590.8(5) A(3), Z = 4; 2, triclinic, space group P1, a = 9.1802(8) A, b = 10.8008(9) A, c = 13.5437(9) A, alpha = 84.491(6) degrees, beta = 75.063(7) degrees, gamma = 79.055(7) degrees, V = 1272.4(2) A(3), Z = 1; 3, triclinic, space group P1, a = 12.110(3) A, b = 12.7273(11) A, c = 18.7054(16) A, alpha = 92.859(7) degrees, beta = 92.200(11) degrees, gamma = 118.057(10) degrees, V = 2534.8(7) A(3), Z = 2. Variation of the counteranions in these systems provides the opportunity to modify the structures and coordination environment of Eu(3+) for 1-3. Compounds 1 and 2 are both one-dimensional, polymeric compounds that contain Eu(3+) ions chelated by terpy and bridged by tetracyanoplatinate anions. 3 is a zero-dimensional complex salt in which Eu(3+) is coordinated by terpy, acetate, and water, but not tetracyanoplatinate. The structural differences result in varying sensitization phenomena for the three compounds. Compounds 1 and 2 display efficient donor-acceptor intramolecular energy transfer (IET) where dual donor species, terpyridine and tetracyanoplatinate, simultaneously enhance the acceptor Eu(3+) emission. In both compounds the donor species are directly coordinated to the acceptor ion, and hence a highly efficient dual-donor effect is exhibited for the IET mechanisms. In 3 where only the terpy ligand is directly coordinated to Eu(3+), the sensitization involves only one donor species. The Pt(CN)(4)(2-) unit in 3, which lacks direct bonding to Eu(3+), exhibits strong emission indicating the lack of cooperative enhancement of the lanthanide emission.

Compact laser cooling apparatus for simultaneous cooling of lithium and rubidium

We report on a dual species laser cooling apparatus capable of collecting over 108 87Rb or 85Rb atoms from an atomic vapor or up to (8±2)×107 6Li atoms directly into a magneto-optic trap (MOT) from an effusive oven without the need for a Zeeman slower. The use of a miniature atomic oven placed close to the trapping region yields a compact vacuum system with a captured flux of more than 4×106 lithium atoms per second and a high quality vacuum in the 10−10 Torr range. The atomic sources, laser system, and vacuum system are described. In addition, we use this system to study atom loss from the MOT due to interspecies collisions between 6Li and 85Rb or 87Rb. We report for the first time the heteronuclear loss coefficients for 6Li-85Rb mixtures.

Microarrays for protease detection in tissues and cells.

Expression of a given protease and of the endogenous inhibitors that regulate protease activity can be readily determined at the transcript level by using whole genome microarray chips. In the case of proteases and protease inhibitors, however, determining which cells are expressing them is often critical to understanding the functional roles of the proteases. For example, in cancer many of the proteases are derived from cells that are found in the microenvironment surrounding the tumor, e.g., fibroblasts and inflammatory cells. Proteases from both fibroblasts and inflammatory cells have been implicated in malignant progression. Therefore, it is important to recognize the origin of these molecules if one is to develop effective therapies. In this regard, mouse transgenic models and xenograft models in which human tumor cells are implanted in mice are useful tools. To profile human and mouse proteases, protease inhibitors, and protease interactors, we have developed in partnership with Affymetrix a custom, single platform, dual species chip: the Hu/Mu ProtIn chip. The Hu/Mu ProtIn chip has been validated for its ability to identify human and mouse transcripts in single species specimens and to identify and distinguish between human and mouse transcripts in dual species specimens such as xenografts. In the latter specimens, the Hu/Mu ProtIn chip has enabled us to identify host (mouse) proteases that play a protective role in development of lung tumors. Here we outline a protocol for using the Hu/Mu ProtIn chip to profile proteases, protease inhibitors, and protease interactors in tissues and cells.

Octodon degus:searching for the key of nocturnalism and diurnalism

Event Abstract Back to Event Octodon degus:searching for the key of nocturnalism and diurnalism María A. Rol1*, Beatriz Otalora1, Pablo Vivanco1 and Juan A. Madrid1 1 University of Murcia, Faculty of Biology, Spain To date, little is known about the mechanisms underlying nocturnalism and diurnalism, and so far most of our knowledge has come from comparing species with different temporal niche. Dual species that are able to shift their activity phase preference are very useful experimental models, since they allow comparisons between individuals and even within the same individual at different time points. The Octodon degus, a diurnal Chilean rodent, can shift to a nocturnal behaviour when provided free access to a running wheel, thus, two distinct chronotypes have been traditionally reported for this species. Our interest has focussed on determining whether this inversion is generated upstream or downstream the clock. Firstly, we have found out a gradient of circadian activity pattern expressions between diurnal and nocturnal animals according to their entrainment phase angle and light masking effect, with core temperature being less affected by light. Moreover, not all animals exhibit this shifting ability. It depends on the individual, and also probably on the environmental temperature and novelty to the wheel exposition, but not age. In order to establish the extend of their temporal order inversion, we have monitored the expression of other overt rhythms (melatonin, cortisol, antioxidant activity, haematological parameters, etc.), analyzed VIP- and AVP-expressing neurons in the suprachiasmatic nucleus, and performed various zeitgeber (photic and non-photic) manipulation. The circadian system of degus seem to be organized as a network of weakly coupled circadian oscillators able to synchronize differentially to photic and non photic cues. The authors want to acknowledge the Ministerio de Ciencia y Tecnología, the Instituto de Salud Carlos III and the Seneca Fundation for their financial support to this project (BFU2007-60658/BFI, RETICEF RD06/0013/0019, 05700/PI/07, respectively, to JA Madrid). Conference: 41st European Brain and Behaviour Society Meeting, Rhodes Island, Greece, 13 Sep - 18 Sep, 2009. Presentation Type: Oral Presentation Topic: Symposia lectures Citation: Rol MA, Otalora B, Vivanco P and Madrid JA (2009). Octodon degus:searching for the key of nocturnalism and diurnalism. Conference Abstract: 41st European Brain and Behaviour Society Meeting. doi: 10.3389/conf.neuro.08.2009.09.047 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 05 Jun 2009; Published Online: 05 Jun 2009. * Correspondence: María A Rol, University of Murcia, Faculty of Biology, Murcia, Spain, angerol@um.es Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers María A Rol Beatriz Otalora Pablo Vivanco Juan A Madrid Google María A Rol Beatriz Otalora Pablo Vivanco Juan A Madrid Google Scholar María A Rol Beatriz Otalora Pablo Vivanco Juan A Madrid PubMed María A Rol Beatriz Otalora Pablo Vivanco Juan A Madrid Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Dynamical pattern formation during growth of a dual-species Bose-Einstein condensate

We simulate the growth of a dual species Bose-Einstein condensate using a Gross-Pitaevskii equation with an additional gain term giving rise to the growth. Such growth occurs during simultaneous evaporative cooling of a mixture of two gases. The ground state of a dual condensate is normally either a miscible mixture, or an immiscible phase with two spatially separated components. In a cigar trap the ground state typically consists of one component in the center, and the other component flanking it. Our simulations show that when the condensates are formed in a cigar trap and the mixture is phase separated, then the final state upon the end of the growth is generally far from the true ground state of the system. Instead it consists of multiple, interleaved bubbles of the two species. Such a pattern was observed recently in an experiment by Wieman's group at JILA [Papp, Pino, and Wieman, Phys. Rev. Lett. 101, 040402 (2008)], and our simulations are in good qualitative agreement with the experiment. We explain the pattern formation as due to the onset of modulation instability during growth, and study the dependence of the final state pattern on various parameters of the system.

Cooperative interactions within a marine bacterial dual species biofilm growing on a natural biodegradable substratum

Pseudoalteromonas sp. S91 is a marine bacterium known to secrete chitinases and pro- teases, hydrolytic enzymes responsible for the degradation of chitin and protein, respectively, which enable access to nutrients contained in chitinous materials such as squid pen. In a dual species biofilm grown on squid pen, Pseudoalteromonas sp. S91 was able to support the accumulation of Vibrio sp. S141, which is unable to degrade squid pen but able to metabolise the chitin subunit N'-acetylglucosamine (GlcNAc), a product of squid pen hydrolysis. When grown on a glass substra- tum in the presence of a soluble carbon source that only Pseudoalteromonas sp. S91 could use, its biofilm provided no support to Vibrio sp. S141.

Species association increases biofilm resistance to chemical and mechanical treatments

The study of biofilm ecology and interactions might help to improve our understanding of their resistance mechanisms to control strategies. Concerns that the diversity of the biofilm communities can affect disinfection efficacy have led us to examine the effect of two antimicrobial agents on two important spoilage bacteria. Studies were conducted on single and dual species biofilms of Bacillus cereus and Pseudomonas fluorescens. Biofilms were formed on a stainless steel rotating device, in a bioreactor, at a constant Reynolds number of agitation (Re A). Biofilm phenotypic characterization showed significant differences, mainly in the metabolic activity and both extracellular proteins and polysaccharides content. Cetyl trimethyl ammonium bromide (CTAB) and glutaraldehyde (GLUT) solutions in conjunction with increasing Re A were used to treat biofilms in order to assess their ability to kill and remove biofilms. B. cereus and P. fluorescens biofilms were stratified in a layered structure with each layer having differential tolerance to chemical and mechanical stresses. Dual species biofilms and P. fluorescens single biofilms had both the highest resistance to removal when pre-treated with CTAB and GLUT, respectively. B. cereus biofilms were the most affected by hydrodynamic disturbance and the most susceptible to antimicrobials. Dual biofilms were more resistant to antimicrobials than each single species biofilm, with a significant proportion of the population remaining in a viable state after exposure to CTAB or GLUT. Moreover, the species association increased the proportion of viable cells of both bacteria, comparatively to the single species scenarios, enhancing each other's survival to antimicrobials and the biofilm shear stress stability.

Endometrial-Peritoneal Interactions during Endometriotic Lesion Establishment

The pathophysiology of endometriosis remains unclear but involves a complex interaction between ectopic endometrium and host peritoneal tissues. We hypothesized that disruption of this interaction would suppress endometriotic lesion formation. We hoped to delineate the molecular and cellular dialogue between ectopic human endometrium and peritoneal tissues in nude mice as a first step toward testing this hypothesis. Human endometrium was xenografted into nude mice, and the resulting lesions were analyzed using microarrays. A novel technique was developed that unambiguously determined whether RNA transcripts identified via microarray analyses originated from human cells (endometrium) or mouse cells (mesothelium). Four key pathways (ubiquitin/proteasome, inflammation, tissue remodeling/repair, and ras-mediated oncogenesis) were revealed, demonstrating communication between host mesothelial cells and ectopic endometrium. Morphometric analysis of nude mouse lesions confirmed that necrosis, inflammation, healing and repair, and cell proliferation occurred during xenograft development. These processes were entirely consistent with the molecular networks revealed by the microarray data. The transcripts detected in the xenografts overlapped with differentially expressed transcripts in a comparison between paired eutopic and ectopic endometria from human endometriotic patients. For the first time, components of the interaction between ectopic endometrium and peritoneal stromal tissues are revealed. Targeted disruption of this dialogue is likely to inhibit endometriotic tissue formation and may prove to be an effective therapeutic strategy for endometriosis.