Wave-related abrasion induces formation of extended spines in a marine bryozoan

Inducible morphology, the conditional expression of morphological characters under certain environmental regimes, is a trait usually found in organisms subject to discrete environmental variability. In marine invertebrates, inducible changes in morphology are usually linked to unpredictable attack by predators or overgrowth competition. We present here evidence that extended spine formation in the marine bryozoan Electra pilosa is inducible by an abiotic cue, wave-related abrasion. In a laboratory experiment, we induced the formation of extended spines by subjecting colonies of E. pilosa to abrasion by seaweeds. We also investigated the potential role of Adalaria proxima, a specialist suctorial nudibranch predator of E. pilosa, in the formation of extended spines. While the presence of the predator does not itself induce extended spine formation, the spines do have a fortuitous anti-predator effect, discouraging predation both by A. proxima and another nudibranch, Polycera quadrilineata. We suggest that extended spines in E. pilosa constitute an adaptation for the protection of feeding polypides in high-energy environments, and that plasticity for the trait is of adaptive value this passively dispersed organism, which exploits in a diverse range of substrata and epifaunal habitats.     

Observations on the clypeasteroid Echinocyamus pusillus (O. F. Müller)

The tiny echinoid Echinocyamus pusillus (O. F. Müller) is equipped with specialized external structures that suit it for a wide variety of environments. Special features include the ability to burrow in sediments of fine sand to shell gravel and to climb vertically.Specimens dredged off the west coast of Scotland were observed in aquaria and with the SEM. E. pusillus is characterized by three kinds of spines, and by two of pedicellariae. In contrast to sand dollars, the spines play a passive rôle in the feeding and burrowing operation, probably retaining a defensive nature as in the regular urchins. It is the podia that are chiefly involved in climbing, burrowing, righting, and probably feeding. Surface ciliary currents transport particles, but not to the mouth; they may have a respiratory or cleansing function. Experimental animals did not burrow in either very fine or very coarse sand, probably because a certain relationship exists between particle weight and podia size.E. pusillus shares behavioural and structural characteristics with regular and irregular urchins. It is not a true sand dollar, but may illustrate an evolutionary stage towards such a form.     

Chemical composition of spines and tests of sea urchins

The skeleton of spines and tests of the species of sea urchins Strongylocentrotus intermedius, Mesocentrotus nudus, Scaphechinus mirabilis, and Echinocardium cordatum from the Sea of Japan is composed of a spongy stereom, consisting of calcite with a high content of magnesium. It was found that the tests and spines of the skeletons of sea urchins are composed of calcium–organic composite materials inlaid with other metals: Mg, Fe, Zn, and Rb. In the four species of sea urchins studied, the strength and other mechanical properties of the tests and spines differ and depend on the chemical composition and structural organization of their components. It was shown that the content of volatile substances correlates with their fragility or elasticity. It is revealed that the chemical composition of the tests of two species of the spherical sea urchins S. intermedius and M. nudus indicates significant differences between these two species of sea urchins.     

Novel Insights into the Proteus mirabilis Crystalline Biofilm Using Real-Time Imaging

The long-term use of indwelling catheters results in a high risk from urinary tract infections (UTI) and blockage. Blockages often occur from crystalline deposits, formed as the pH rises due to the action of urease-producing bacteria; the most commonly found species being Proteus mirabilis. These crystalline biofilms have been found to develop on all catheter materials with P. mirabilis attaching to all surfaces and forming encrustations. Previous studies have mainly relied on electron microscopy to describe this process but there remains a lack of understanding into the stages of biofilm formation. Using an advanced light microscopy technique, episcopic differential interference contrast (EDIC) microscopy combined with epifluorescence (EF), we describe a non-destructive, non-contact, real-time imaging method used to track all stages of biofilm development from initial single cell attachment to complex crystalline biofilm formation. Using a simple six-well plate system, attachment of P. mirabilis (in artificial urine) to sections of silicone and hydrogel latex catheters was tracked over time (up to 24 days). Using EDIC and EF we show how initial attachment occurred in less than 1 h following exposure to P. mirabilis. This was rapidly followed by an accumulation of an additional material (indicated to be carbohydrate based using lectin staining) and the presence of highly elongated, motile cells. After 24 h exposure, a layer developed above this conditioning film and within 4 days the entire surface (of both catheter materials) was covered with diffuse crystalline deposits with defined crystals embedded. Using three-dimensional image reconstruction software, cells of P. mirabilis were seen covering the crystal surfaces. EDIC microscopy could resolve these four components of the complex crystalline biofilm and the close relationship between P. mirabilis and the crystals. This real-time imaging technique permits study of this complex biofilm development with no risk of artefacts due to sample manipulation. A full understanding of the stages and components involved in crystalline encrustation formation will aid in the development of new protocols to manage and ultimately prevent catheter blockage.     

Biotesting of water quality in Peter the Great Bay with the use of the microalga Dunaliella salina and embryos and larvae of the sea urchin Scaphechinus mirabilis

Comparative biotesting was performed using embryos and larvae of the sea urchin Scaphechinus mirabilis and the microalga Dunaliella salina. These two species were taken as test organisms for estimating water quality in areas of various anthropogenic loads. Seawater from Nakhodka and Vostok bays, as well as from the southwestern part of Peter the Great Bay (Sea of Japan) near the Tumen River mouth, was tested. Water from Vostok and Nakhodka bays had a harmful effect on embryonic and larval development of the sea urchin. The algal culture kept in the water of Vostok Bay was depressed throughout the experiment, while development of the alga in the water from Nakhodka Bay hardly differed from the control but was unstable. Water from the southwestern part of Peter the Great Bay did not have any significant harmful effect on both test organisms. Embryos and larvae of the sea urchin S. mirabilis were several orders more sensitive to salinity changes and content of toxic agents; they responded more readily to changes in water quality than D. salina cells. Correspondingly, embryos and larvae of the sea urchin S. mirabilis were found to be a preferable test organism for assessment of pollution in various marine environments.     

Inverted sand dollars actively orient themselves in flow to increase likelihood of righting

The fact that sand dollars are often dislodged and inverted is an inescapable consequence of living at or slightly below the sediment–water interface. Once inverted, however, how do sand dollars effectively right themselves, given their small spines and stiff internal skeletons? Here, we examined the possibility that individuals of Mellita quinquiesperforata and Dendraster excentricus may take advantage of the interaction of their morphology and flow to increase the likelihood of righting. Based on flow tank observations, the critical velocity required to flip an inverted sand dollar varies with orientation and increases with test size. For both species, the critical velocity was lower when inverted sand dollars were oriented with the posterior margin facing directly downstream, compared with when the posterior margin was positioned in an upstream orientation. To test whether inverted sand dollars would actively rotate into a more advantageous position for flipping, we exposed inverted animals in three starting orientations – with their posterior edge directed upstream (the least favored position for flipping), perpendicular, and downstream to flow – to the minimum flow expected to induce flipping and compared their responses. Time‐lapse photography showed that regardless of initial orientation, within one hour, a majority of individuals of both species rotated into positions that were not statistically different from the downstream orientation (the most favored position for flipping). These results for D. excentricus were further confirmed in a field experiment. Taken together, these data suggest that inverted sand dollars are able to recognize flow direction and respond by modifying their orientation to maximize lift and drag for righting.     

Evolutionary modification of T-brain (tbr) expression patterns in sand dollar

The sand dollars are a group of irregular echinoids that diverged from other regular sea urchins approximately 200 million years ago. We isolated two orthologs of T-brain (tbr), Smtbr and Pjtbr, from the indirect developing sand dollar Scaphechinus mirabilis and the direct developing sand dollar Peronella japonica, respectively. The expression patterns of Smtbr and Pjtbr during early development were examined by whole mount in situ hybridization. The expression of Smtbr was first detected in micromere descendants in early blastula stage, similar to tbr expression in regular sea urchins. However, unlike in regular sea urchin, Smtbr expression in middle blastula stage was detected in micromere-descendent cells and a subset of macromere-descendant cells. At gastrula stage, expression of Smtbr was detected in part of the archenteron as well as primary mesenchyme cells. A similar pattern of tbr expression was observed in early Peronella embryos. A comparison of tbr expression patterns between sand dollars and other echinoderm species suggested that broader expression in the endomesoderm is an ancestral character of echinoderms. In addition to the endomesoderm, Pjtbr expression was detected in the apical organ, the animal-most part of the ectoderm.     

Hydrodynamic analysis of feeding in sand dollars

Summary Subtidal sand dollars, Dendraster excentricus, assume an inclined posture under conditions of moderate water flow (10 cm s^-1 to 2 m s^-1). In this posture, when the test is in the usual position parallel to the water flow, the test acts as a lifting body. Analysis of the hydrodynamic characteristics of the sand dollar test was accomplished by slender body theory. Streamline curvature due to lift moves food particles in the direction of the feeding surface and enhances feeding efficiency. The position parallel to water flow is most advantageous to sand dollars in reversing flows, such as wave surge, whereas sand dollars in unidirectional flows can place the test at a slight angle to the water flow to increase lift. The high camber of sand dollars from a bay habitat characterized by low water velocities was interpreted as an adaptation allowing efficient lift production in low velocity flows; sand dollars from a protected outer coast location characterized by higher water velocities were significantly less cambered.Within sand dollar beds, the animals alter their spacing as a function of the water velocity. This movement is construed as a method for maintaining the optimal gap between sand dollars. Sand dollar tests induce mutual interference effects which vary with the configuration of the animals. In the prevalent configuration, sand dollars are able to take advantage of the streamline curvature induced by neighboring animals. The optimal gap increases as the square of the water velocity. At distances grater than or less than the optimal gap, feeding efficiency was shown to decrease from that at the optimal gap.     

Structure and function of clypeasteroid miliary spines (Echinodermata,Echinoides)

Summary Histological and ultrastructural techniques have been used to describe the functional morphology of clypeasteroid miliary spines, with special reference to their supposed mucus-secreting role. Mucus cells were not found in the miliary spines of any members of the Arachnoididae, Fibulariidae, Laganidae, Echinarachniidae, Dendrasteridae, Astriclypeidae, or Mellitidae examined in this study. Only members of the Clypeasteridae have mucus-secreting cells in these spines. Characteristics of the skeleton, ultrastructure of the nervous system, and histology of the musculature and epithelia of the base, shaft and tip are also discussed. Miliary spines have two bands of cilia running along the entire length of opposite sides of the shaft. The geometric packing of cilium-bearing cells in these bands is described for the first time, as is the remarkable form of the sacs found at the tips of dendrasterid, astriclypeid, and mellitid miliary spines. These sacs are definitely not mucous sacs, as previously described, but are balloons of single-celled epithelium internally tethered to the skeletal tip by copious quantities of collagenous connective tissue. Miliary spines prevent obstruction of aboral nutritive and ventilatory ciliary currents caused by substrate particles falling to the test surface during burrowing. They do this in two ways: (1) they help generate ciliary currents that sweep finer material off the test, and (2) they contribute to the formation of a spine canopy that mechanically blocks larger particles from falling between the spines. Members of the Clypeasteridae secrete an interspine mucous tent that traps potentially clogging material. The miliary spine sacs of sand dollars are deformable space-fillers that plug holes between primary spines in the aboral canopy, even as the spines rock on their tubercles to push sand backwards over the test. Allometry of spines from Echinarachnius parma suggests that aboral military spines and club-shaped spines exhibit co-ordinated growth that maintains the aboral canopy throughout post-metamorphic ontogeny, and that aboral spins have an overall lower growth rate than spines on the oral surface.     

The ectosymbiont crab Dissodactylus mellitae-sand dollar Mellita isometra relationship

The presence of the ectosymbiont Dissodactylus mellitae on Mellita isometra was studied at Tybee Island in Georgia. The number of crabs found on sand dollars, stage of maturity, sex, numbers of eggs, and size of eggs produced by crabs were noted. The test diameter of sand dollars, and the number and diameter of eggs produced were also noted. Infestation rates of crabs on sand dollars varied over time. The maximum number of crabs found on a sand dollar was 10. The three types of population dispersion, random, uniform, and clumped, were observed for crabs on sand dollars throughout the sampling period. Clumped or gregarious settling was observed when juvenile crabs were abundant, uniform and random distribution when mature crabs were abundant. Female crabs were significantly larger than male crabs, with carapace width of the largest mature female crab being 4.6 mm and the largest male 3.1 mm. Crabs produced between 80 and 300 eggs from 0.188 to 0.291 mm in diameter. Bigger crabs produced significantly more eggs than smaller crabs. Sand dollar sizes were 50-110 mm, with a mode between 60 and 70 mm. The effect of crab burden on egg production in the sand dollar was time-dependent. The presence of crabs on sand dollars correlated with total egg production of sand dollars in May, the peak of the spawning season, with sand dollars carrying one or two crabs having a lower egg production than those without crabs. Overall, variation in egg size was attributed to variation among females followed by variation between seasons and crab burden.     

Establishment and Application of a Dual TaqMan Real-Time PCR Method for Proteus Mirabilis and Proteus Vulgaris

Proteus species are common opportunistic bacteria and foodborne pathogens. The proper detection of Proteus can effectively reduce the occurrence of food-borne public health events. Proteus mirabilis and Proteus vulgaris are the two most important pathogens in the Proteus genus. In this study, a dual TaqMan Real-Time PCR method was established to simultaneously detect and distinguish P. mirabilis and P. vulgaris in samples. The method exhibited good specificity, stability, and sensitivity. Specifically, the minimum detection concentrations of P. mirabilis and P. vulgaris in pure bacterial cultures were 6.08 × 10² colony forming units (CFU)/ml and 4.46 × 10² CFU/ml, respectively. Additionally, the minimum detectable number of P. mirabilis and P. vulgaris in meat and milk was 10³ CFU/g. In addition, the method can be used to distinguish between strains of P. mirabilis and P. vulgaris within two hours. Overall, it is a sensitive, easy-to-use, and practical test for the identification and classification of Proteus in food.Key words: Proteus mirabilis, Proteus vulgaris, TaqMan Real-Time PCR, food-borne pathogens, food poisoning     

Loss of FliL Alters Proteus mirabilis Surface Sensing and Temperature-Dependent Swarming

Proteus mirabilis is a dimorphic motile bacterium well known for its flagellum-dependent swarming motility over surfaces. In liquid, P. mirabilis cells are 1.5- to 2.0-μm swimmer cells with 4 to 6 flagella. When P. mirabilis encounters a solid surface, where flagellar rotation is limited, swimmer cells differentiate into elongated (10- to 80-μm), highly flagellated swarmer cells. In order for P. mirabilis to swarm, it first needs to detect a surface. The ubiquitous but functionally enigmatic flagellar basal body protein FliL is involved in P. mirabilis surface sensing. Previous studies have suggested that FliL is essential for swarming through its involvement in viscosity-dependent monitoring of flagellar rotation. In this study, we constructed and characterized ΔfliL mutants of P. mirabilis and Escherichia coli. Unexpectedly and unlike other fliL mutants, both P. mirabilis and E. coli ΔfliL cells swarm (Swr⁺). Further analysis revealed that P. mirabilis ΔfliL cells also exhibit an alteration in their ability to sense a surface: e.g., ΔfliL P. mirabilis cells swarm precociously over surfaces with low viscosity that normally impede wild-type swarming. Precocious swarming is due to an increase in the number of elongated swarmer cells in the population. Loss of fliL also results in an inhibition of swarming at <30°C. E. coli ΔfliL cells also exhibit temperature-sensitive swarming. These results suggest an involvement of FliL in the energetics and function of the flagellar motor.     

Chondrichthyan teeth from the Early Triassic Paris Biota (Bear Lake County,Idaho, USA)

A new, diverse and complex Early Triassic assemblage was recently discovered west of the town of Paris, Idaho (Bear Lake County), USA. This assemblage has been coined the Paris Biota. Dated earliest Spathian (i.e., early late Olenekian), the Paris Biota provides further evidence that the biotic recovery from the end-Permian mass extinction was well underway ca. 1.3 million years after the event. This assemblage includes mainly invertebrates, but also vertebrate remains such as ichthyoliths (isolated skeletal remains of fishes). Here we describe first fossils of Chondrichthyes (cartilaginous fishes) from the Paris Biota. The material is composed of isolated teeth (mostly grinding teeth) preserved on two slabs and representing two distinct taxa. Due to incomplete preservation and morphological differences to known taxa, the chondrichthyans from the Paris Biota are provisionally kept in open nomenclature, as Hybodontiformes gen. et sp. indet. A and Hybodontiformes gen. et sp. indet. B, respectively. The present study adds a new occurrence to the chondrichthyan fossil record of the marine Early Triassic western USA Basin, from where other isolated teeth (Omanoselache, other Hybodontiformes) as well as fin spines of Nemacanthus (Neoselachii) and Pyknotylacanthus (Ctenachanthoidea) and denticles have been described previously.     

Effect of traditionally used herb Pedalium murex L. and its active compound pedalitin on urease expression – For the management of kidney stone

Pedalium murex L. is a medicinal herb that has been used for the treatment of diseases related to kidney in the traditional system of medicine. The current study aims to study the effect of ethyl acetate extract of P. murex (EAEP) and its fractionated compound pedalitin against urease production and UreC gene expression in Proteus mirabilis. The selected reference strain Proteus mirabilis (MTCC 425) and the isolates culture of Proteus mirabilis were subjected to study the antibacterial efficacy of P. murex. Expression analysis of P. mirabilis urease gene was successfully done by QPCR. The ethyl acetate extract effectively inhibit the reference Proteus mirabilis and bacterial isolates of Proteus mirabilis in the clinical samples studied. EAEP has showed more potent activity (56.7%) against urease enzyme and pedalitin also exhibited potent activity (30.1%). Using qPCR, the expression of UreC gene of P. mirabilis was controlled by EAEP and also its bioactive compound pedalitin. The present study clearly demonstrated the potency of P. murex in controlling the growth of pathogenic P. mirabilis and to control the expression of urease enzyme production as well as to restrict the urease gene expression in P. mirabilis.     

Expression of amino acid transporter genes in developmental stages and adult tissues of Antarctic echinoderms

Epithelial cells in the body wall of adult and developmental stages of marine invertebrates absorb dissolved organic material directly from seawater. Despite over a century of study, little is known about the molecular biological mechanisms responsible for this transport process. Previous studies on embryonic and larval Antarctic echinoderms show that amino acid uptake could provide an important supplement of metabolic substrates. In the present study, partial cDNA sequences of 11 putative amino acid transporter genes were isolated from six species of Antarctic echinoderms including the Antarctic sea stars Acodontaster hodgsoni, Diplasterias brucei, Odontaster meridionalis, Odontaster validus, and Perknaster fuscus, and the Antarctic sea urchin Sterechinus neumayeri. Conserved domains of cDNA-deduced amino acid sequences characterized these genes as being members of a family of amino acid transporters (solute carrier family 6). Expression of these genes was detected throughout embryonic and larval development of two species that have contrasting developmental modes (A. hodgsoni: lecithotrophic; O. meridionalis: planktotrophic). In all six species studied, the expression of amino acid transporter genes was detected in tube feet and digestive organs of adult animals, demonstrating that members of a single amino acid transporter gene family are expressed during the entire life history of a marine invertebrate. The identification of these genes is an important step toward developing a mechanistic understanding of amino acid transport capacities in Antarctic marine invertebrates.     

Preferential Use of Central Metabolism In Vivo Reveals a Nutritional Basis for Polymicrobial Infection

The human genitourinary tract is a common anatomical niche for polymicrobial infection and a leading site for the development of bacteremia and sepsis. Most uncomplicated, community-acquired urinary tract infections (UTI) are caused by Escherichia coli, while another bacterium, Proteus mirabilis, is more often associated with complicated UTI. Here, we report that uropathogenic E. coli and P. mirabilis have divergent requirements for specific central pathways in vivo despite colonizing and occupying the same host environment. Using mutants of specific central metabolism enzymes, we determined glycolysis mutants lacking pgi, tpiA, pfkA, or pykA all have fitness defects in vivo for P. mirabilis but do not affect colonization of E. coli during UTI. Similarly, the oxidative pentose phosphate pathway is required only for P. mirabilis in vivo. In contrast, gluconeogenesis is required only for E. coli fitness in vivo. The remarkable difference in central pathway utilization between E. coli and P. mirabilis during experimental UTI was also observed for TCA cycle mutants in sdhB, fumC, and frdA. The distinct in vivo requirements between these pathogens suggest E. coli and P. mirabilis are not direct competitors within host urinary tract nutritional niche. In support of this, we found that co-infection with E. coli and P. mirabilis wild-type strains enhanced bacterial colonization and persistence of both pathogens during UTI. Our results reveal that complementary utilization of central carbon metabolism facilitates polymicrobial disease and suggests microbial activity in vivo alters the host urinary tract nutritional niche.     

Quick identification and quantification of Proteus mirabilis by polymerase chain reaction (PCR) assays

Proteus mirabilis is an opportunistic pathogen that can cause urinary tract infection in human beings. The accurate and rapid identification and quantification of P. mirabilis is necessary for early treatment. In this study, a pair of specific primers according to the conserved ureR sequence of P. mirabilis was designed and novel systems which consisted of a polymerase chain reaction (PCR) and a real-time PCR to identify and quantify P. mirabilis were developed. For the qualitative identification by ordinary PCR, a 225-bp DNA product was amplified from P. mirabilis and separated on an agarose gel. The corresponding DNA product is present in three P. mirabilis strains isolated from different geographical locations, but is absent in 20 strains representing 18 different species, including the ureR homolog contained Providencia stuartii and Escherichia coli strains, the other common pathogens Klebsiella sp., Edwarsiella sp., Vibrio sp., Enterobacter sp., and Escherichia sp., and other environmental bacteria Pseudomonas sp. and Acinetobacter sp. Proteus mirabilis at concentrations higher than 1.0?×?10³ CFU ml^?1 was detectable by ordinary PCR; P. mirabilis at concentrations higher than 10 CFU ml^?1 was quantified by real-time PCR. The specific, sensitive and time-efficient PCR methods were demonstrated to be applicable to rapid identification and quantification of P. mirabilis.     

Anti-biofilm activity of LC-MS based Solanum nigrum essential oils against multi drug resistant biofilm forming P. mirabilis

Urinary tract infections are second most important diseases worldwide due to the increased amount of antibiotic resistant microbes. Among the Gram negative bacteria, P. mirabilis is the dominant biofilm producer in urinary tract infections next to E. coli. Biofilm is a process that produced self-matrix of more virulence pathogens on colloidal surfaces. Based on the above fact, this study was concentrated to inhibit the P. mirabilis biofilm formation by various in-vitro experiments. In the current study, the anti-biofilm effect of essential oils was recovered from the medicinal plant of Solanum nigrum, and confirmed the available essential oils by liquid chromatography-mass spectroscopy analysis. The excellent anti-microbial activity and minimum biofilm inhibition concentration of the essential oils against P. mirabilis was indicated at 200 µg/mL. The absence of viability and altered exopolysaccharide structure of treated cells were showed by biofilm metabolic assay and phenol–sulphuric acid method. The fluorescence differentiation of P. mirabilis treated cells was showed with more damages by confocal laser scanning electron microscope. Further, more morphological changes of essential oils treated cells were differentiated from normal cells by scanning electron microscope. Altogether, the results were reported that the S. nigrum essential oils have anti-biofilm ability.     

Identification of a cytochrome b5-fusion desaturase responsible for the synthesis of triunsaturated sphingolipid long chain bases in the marine diatom Thalassiosira pseudonana

Triunsaturated sphingolipid long chain bases (LCBs) have previously been reported in some specialised tissues of marine invertebrates. We report the presence of similar LCBs in the marine diatom Thalassiosira pseudonana and identify the cytochrome b5-fusion desaturase responsible for the introduction of the third double bond at the Δ10 position in d18:3Δ4,8,10. This study extends the catalytic repertoire of the cytochrome b5 fusion desaturase family, also indicating the presence of orthologues in other marine invertebrates. The function of these polyunsaturated sphingolipid LCBs is currently unknown but it was previously suggested that they play an essential role in primitive animals. The identification of the desaturase responsible for their synthesis paves the way for further studies.