Sessile Forms Research Articles

A deployable decentralized biofilm system for degrading organic carbon and benzene in wastewater

A fixed biofilm system was explored for decentralized wastewater treatment utilizing laboratory cultivated microorganisms including Gordonia sp. The system is deployable in a 40‐ft ISO container/trailer or on a C‐130 aircraft. Experimental results indicated that pre‐addition of raw wastewater to the microbial culture before inoculation resulted in a significantly higher BOD5 degradation (77 ± 2% in 24 h) than the consortium alone (58 ± 10%) during the startup of the system. After the pilot system was in semi‐continuous operation with an average flow rate of 13.2 L/min, the removal efficiency of BOD5 and total suspended solids (TSS) was 83 ± 9 and 84 ± 9, respectively. As an important supplement to the pilot studies, laboratorial tests by headspace analysis showed that the Gordonia sp. were able to degrade benzene in water. More significant biodegradation of benzene was found in sessile form (57 ± 8%) than in planktonic form (25 ± 11%) with minimal glucose in 26 h. However, no benzene degradation was found in sessile form when no glucose was supplied. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 505–511, 2013

Predator-induced macroevolutionary trends in Mesozoic crinoids

Sea urchins are a major component of recent marine communities where they exert a key role as grazers and benthic predators. However, their impact on past marine organisms, such as crinoids, is hard to infer in the fossil record. Analysis of bite mark frequencies on crinoid columnals and comprehensive genus-level diversity data provide unique insights into the importance of sea urchin predation through geologic time. These data show that over the Mesozoic, predation intensity on crinoids, as measured by bite mark frequencies on columnals, changed in step with diversity of sea urchins. Moreover, Mesozoic diversity changes in the predatory sea urchins show a positive correlation with diversity of motile crinoids and a negative correlation with diversity of sessile crinoids, consistent with a crinoid motility representing an effective escape strategy. We contend that the Mesozoic diversity history of crinoids likely represents a macroevolutionary response to changes in sea urchin predation pressure and that it may have set the stage for the recent pattern of crinoid diversity in which motile forms greatly predominate and sessile forms are restricted to deep-water refugia.

Aerobic treatment of dairy wastewater in an industrial three-reactor plant: Effect of aeration regime on performances and on protozoan and bacterial communities

An industrial three-reactor plant treating 45 m3 d−1 of dairy wastewater was monitored to investigate the effect of different aeration regimes on performance efficiency and to find relationships with bacterial and protozoan communities in the activated sludge. During the study, the plant was maintained at six different “on/off” cycles of the blower (45/15, 15/15, 15/45, 30/30, 30/45 and 30/60 min), providing between 30.2 and 90.6 kg O2 d−1, and the main chemical/biochemical parameters (COD, BOD, NH4+, NO2−, NO3−, PO43−, etc.) were determined. When at least 45.4 kg O2 d−1 (30/45) were provided, COD removal efficiencies were always in the range 88–94% but decreased to about 70% under aeration regimes 15/45 and 30/60. Ammonium ion degradation performance was compromised only in the lowest aeration regime (15/45). Total number of protozoa and their species richness, and bacterial viable counts and denaturing gradient gel electrophoresis (DGGE) profiles were used to characterize the microbiota of the activated sludge. Cell abundances and community structures of protozoa and bacteria were very similar in the three aerated reactors but changed with the aeration regimes. In particular, the 15/45 and 30/60 regimes led to low protozoan diversity with prevalence of flagellates of the genus Trepomonas at the expense of the mobile and sessile forms and, thus, to a less efficient activated sludge as indicated by Sludge Biotic Index values (3 and 4.5 for the two regimes, respectively). The structure of the bacterial community strongly changed when the aeration regimes varied, as indicated by the low similarity values between the DGGE profiles. On the contrary, number of viable bacteria and values of the biodiversity index remained stable throughout the whole experimentation. Taken together, the results of the present study clearly indicate that aeration regime variations strongly influence the structure of both protozoan and bacterial communities and, above all, that a high biodiversity among protozoan populations in the activated sludge is prerequisite for high performances in dairy wastewater treatment.

Efficacy of intravascular catheter lock solutions containing preservatives in the prevention of microbial colonization

There is little published evidence regarding whether heparin lock solutions containing preservatives prevent catheter-related infections. However, adverse effects from preservative-containing flushes have been documented in neonates, leading many hospitals to avoid their use altogether. Infection control records from 1982 to 2008 at St. Jude Children's Research Hospital (SJCRH) were reviewed regarding the incidence of catheter-related infections and the use of preservative-containing intravenous locks. In addition, the antimicrobial activities of heparin lock solution containing the preservatives parabens (0.165%) or benzyl alcohol (0.9%), and 70% ethanol were examined against Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli, Bacillus cereus, Pseudomonas aeruginosa and Candida albicans, and compared with preservative-free saline with and without heparin. Growth was assessed after exposure to test solutions for 0, 2, 4 and 24h at 35 °C. The activities of preservatives were assessed against both planktonic (free-floating) and sessile (biofilm-embedded) micro-organisms using the MBEC Assay. Infection control records revealed two periods of increased catheter-related infections, corresponding with two intervals when preservative-free heparin was used at SJCRH. Heparin solution containing preservatives demonstrated significant antimicrobial activity against both planktonic and sessile forms of all six microbial species. Ethanol demonstrated the greatest antimicrobial activity, especially following short incubation periods. Heparin lock solutions containing the preservatives parabens or benzyl alcohol, and 70% ethanol demonstrated significant antimicrobial activity against both planktonic and sessile micro-organisms commonly responsible for catheter-related infections. These findings, together with the authors' historical infection control experience, support the use of preservatives in intravenous lock solutions to reduce catheter related infections in patients beyond the neonatal period.

Prevalence of mutans streptococci isolated from complete dentures and their susceptibility to mouthrinses

The aims of this study were to evaluate the incidence of mutans streptococci (MS - sessile form) on complete maxillary dentures after use of a specific denture paste, and to determine the minimum inhibitory concentration (MIC) and maximum inhibitory dilution (MID) of 3 oral mouthrinses: Cepacol, Plax and Periogard. Seventy-seven complete denture wearers were randomly assigned into 2 groups, according to the product used for denture cleaning: Control group - conventional dentifrice (Kolynos-Super White); and Test group: experimental denture cleaning paste. Denture biofilm was collected at baseline and after 90 and 180 days after treatment by brushing the dentures with saline solution. After decimal serial dilution, samples were seeded onto agar sucrose bacitracin to count colonies with morphological characteristics of MS. MS identification was performed by the sugar fermentation tests. After this procedure, brain heart infusion broth (BHI) was added to oral mouthrinses (Plax, Cepacol e Periogard) and seeded on Petri dishes. The colonies were seeded using the Steers multiplier and, after the incubation, the MIC and MID of the mouthrinses were calculated. The results showed an incidence of 74.0% (n=57) of MS in the 77 complete dentures examined in the study, being 76.3% (n=29) of the Control group (conventional dentifrice) and 71.8% (28) of the Test group (experimental denture cleaning paste). In both groups, the number of positive cases for MS decreased from day 0 to day 180. In the Test group there was a slight decrease in the incidence of Streptococcus mutans 90 days after use of the experimental denture cleaning paste, which was not observed in the Control group. As regards to mouthrinses, for both groups, Periogard showed antimicrobial action with the highest dilution, followed by Cepacol and Plax. In conclusion, the incidence of MS in complete dentures was high and Periogard was the mouthrinse with the strongest antimicrobial action against MS. The experimental denture cleaning paste showed a slight action against S. mutans after 90 days of treatment.

Escherichia coli Variants in Periprosthetic Joint Infection: Diagnostic Challenges with Sessile Bacteria and Sonication

The diagnostic yield of prosthetic joint-associated infection is hampered by the phenotypic change of bacteria into a sessile and resistant form, also called biofilm. With sonication, adherent bacteria can be dislodged from the prosthesis. Species identification may be difficult because of their variations in phenotypic appearance and biochemical reaction. We have studied the phenotypic, genotypic, and biochemical properties of Escherichia coli variants isolated from a periprosthetic joint infection. The strains were collected from synovial fluid, periprosthetic tissue, and fluid from the explanted and sonicated prosthesis. Isolates from synovial fluid revealed a normal phenotype, whereas a few variants from periprosthetic tissue and all isolates from sonication fluid showed different morphological features (including small-colony variants). All isolates from sonication fluid were beta-galactosidase negative and nonmotile; most were indole negative. Because of further variations in biochemical properties, species identification was false or not possible in 50% of the isolates included in this study. In contrast to normal phenotypes, variants were resistant to aminoglycosides. Typing of the isolates using pulsed-field gel electrophoresis yielded nonidentical banding patterns, but all strains were assigned to the same clonal origin when compared with 207 unrelated E. coli isolates. The bacteria were repeatedly passaged on culture media and reanalyzed. Thereafter, most variants reverted to normal phenotype and regained their motility and certain biochemical properties. In addition, some variants displayed aminoglycoside susceptibility after reversion. Sonication of an explanted prosthesis allows insight into the lifestyle of bacteria in biofilms. Since sonication fluid also reveals dislodged sessile forms, species identification of such variants may be misleading.

Ratio‐ and Predator‐Dependent Functional Forms for Predators Optimally Foraging in Patches

Functional forms of predator-prey interactions are developed for predators optimally foraging on prey distributed in patches. The model uses mean free-path-length theory to develop functional forms for two idealized behaviors of prey in patches. For congregating prey that maintain a fixed density, for example, fish schools, the predation rate has a ratio-dependent form, and predator interference depends only on predator density. For sessile prey, which maintain a fixed patch size, a new predator-dependent form emerges in which predator interference depends on both prey and predator densities. The Beddington-DeAngelis equation is a special case of the sessile form. The model provides behavioral and biological criteria with which to select the functional form and ranges of coefficients appropriate for a particular food web. Finally, the model illustrates that behavior is an essential factor in predator-prey dynamics.

Control of Sulfate-Reducing Bacteria in Oil and Gas Pipelines

This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper SPE 118410, "Control of Sulfate-Reducing Bacteria in Oil and Gas Pipelines," by M.D. Lohithesh and A.K. Agnihotri, ONGC, and Banwari Lal, SPE, TERI, prepared for the 2008 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, UAE, 3-6 November. The paper has not been peer reviewed. A major economic loss faced by oil and gas companies is pipeline corrosion. Internal pipeline corrosion is, basically, caused by sulfate-reducing bacteria (SRB). The growth of SRB and their secondary metabolites in pipelines causes surface modifications, which can induce a more-complex corrosion process. A strategy was studied for controlling the SRB population of oil and gas pipelines. Introduction Microbial-induced corrosion (MIC) has been implicated widely in the deterioration of metal pipelines and offshore structures in the oil industry. Though several studies have reported the use of chemicals as biocides for controlling MIC, these conventional methods generally are inadequate against bacterial biofilms. Metabolically active bacteria exhibit an increased tendency to attach to metal surfaces and, depending on the availability of nutrients, to produce exopolymers to form mature biofilms. The exopolysaccharide matrix that helps form the biofilm may be involved in reducing the reactivity of chemical biocides. Attempts to circumvent this problem have focused on use of very high concentrations of chemical biocides, which may in turn pose environmental hazards. Further, after a long period of contact, corrosion-causing bacterial microflora might adapt to a given biocide and develop resistance. It is established that even if biocides are effective against planktonic population (i.e., dispersed in the water phase), their effectiveness against sessile forms (i.e., embedded within biofilm) is reduced by approximately 90%. Therefore, development continues for effective biocides, appropriate procedure for their application, and innovative measures for microbial control. This study explored the effect of biocides on the inhibition of SRB in oil pipelines. The objectives were to screen efficient and effective biocides for inhibition of MIC in oil pipelines, examine the potential of effective biocides by measuring the total sulfide production, and demonstrate the ability of biocides against biofilm (sessile population). Materials and Methods Oil and water samples were collected from the pipeline network of Oil and Natural Gas Corporation (ONGC), India, at the Bombay high offshore, Gandhar, and Ahmedabad areas. Production fluid was collected directly from the production wellheads. The SRB consortium was developed from formation water collected from corroded oil pipelines The SRB medium was prepared by adding 25 g of NaHCO3, 0.2 g of CaCl2•2H2O, 0.1 g of KCl, 1.5 g of NH4Cl, 0.6 g of NaH2PO4•H2O, 10.0 mL of vita-min, and 10 mL of trace element with a molarity of 50 mM (millimolar =mol/m3) ferric citrate in 1 L of double-distilled water. The pH of the medium was adjusted to 7.5±0.1 by use of 1 M NaOH. The SRB consortium was purified by the roll-tube method, and individual strains were identified by use of 16S rDNA analysis.

Implications of bacterial biofilms in chronic rhinosinusitis

The recognition of sessile form of bacteria with particular features, known as biofilm, has given new insights to the understanding of pathogenesis of several chronic diseases, including Chronic Rhinosinusitis (CRS). In this article we review the main characteristics of biofilms, describe the current methods used to demonstrate biofilms in chronic rhinosinusitis and discuss the future directions of research in the field.

Setal morphology and cirral setation of thoracican barnacle cirri: adaptations and implications for thoracican evolution

AbstractThoracic cirripedes are sessile crustaceans that use six pairs of thoracic appendages (the cirri) to catch and handle food. We used scanning electron microscopy to examine the cirri, which include one to three pairs of maxillipeds in six species of thoracican barnacles, in search of correlations between cirral setation and feeding mode. The species studied comprise both pedunculate and sessile forms and represent a wide range of marine habitats as well as morphologies, viz., Ibla cumingi, Octolasmis warwickii, Capitulum mitella, Pollicipes polymerus, Tetraclita japonica japonica and Megabalanus volcano. Of the pedunculates, I. cumingi has the least complex setation pattern consisting of only serrulate types. This is consistent with its very simplified feeding mode and an apparent inability to discriminate between food items. Octolasmis warwickii is slightly more modified, while both P. polymerus and C. mitella have a more diversified setation. The balanomorphan species exhibit by far the most complex cirral setation. This is consistent with the several types of suspension feeding seen in these species, their ability to identify and sort captured food items and even to perform microfiltration in the mantle cavity using the setae on their three pairs of maxillipeds. Our results indicate that in thoracican barnacles, adaptations in feeding behaviour are associated with changes in the setation pattern of the cirri. In addition, the setal types and their distribution on the cirri are potential new characters in future morphology‐based analyses of the phylogeny of the Cirripedia Thoracica.

Plant-associated invertebrates and hydrological balance in the large volcanic Lake Bracciano (Central Italy) during two years with different water levels

Lakes in the Mediterranean region experience an altered hydrological balance with large water level reductions and/or fluctuations within and between years. To date, little is known about the reaction of invertebrate assemblages inhabiting the littoral zone to water level changes in natural lakes. Here, we present the case of the volcanic Lake Bracciano, one of the largest and deepest Italian lakes. We compared the numerical composition and taxonomic richness of plant-associated invertebrate assemblages sampled from three sites and three depth ranges (0–4 m, 4–8 m and 8–15 m) between years with different water levels. Using historical data, we built a hydrological balance model to assess the role of different water budget components on the water levels. The hydrological balance showed that the volume of water currently abstracted for human use exceeds the potential changes caused by the projected warming of climate and decreasing amount of precipitation by nearly an order of magnitude. In a low water level year, littoral macrophytes and invertebrate assemblages exhibited qualitative and quantitative differences at all sampling sites and depths. The invertebrate assemblage showed a reduced taxonomic richness and lower numerical abundance of the more sessile forms (water mites, gastropods, nematodes, naidid oligochaetes), which feed directly on living plants or epiphytic algae, and an increase of more mobile and/or detritivore taxa.

Small-scale distribution of deep-sea demersal nekton and other megafauna in the Charlie-Gibbs Fracture Zone of the Mid-Atlantic Ridge

Abstract Videotapes from manned submersibles diving in the area of the Charlie-Gibbs Fracture Zone of the Mid-Atlantic Ridge were used to investigate the distribution of fishes, large crustaceans, epifaunal and sessile organisms, and environmental features along a series of transects. Submersibles MIR 1 and MIR 2 conducted paired dives in an area of mixed sediment and rock (beginning depth ca. 3000 m) and on a large pocket of abyssal-like sediments (depth ca. 4000 m). In the shallower area, the submersibles passed over extremely heterogeneous terrain with a diversity of nekton, epifaunal forms and sessile forms. In the first pair of dives, MIR 1 rose along the Mid-Atlantic Ridge from 3000 to 1700 m, while MIR 2 remained near the 3000 m isobath. Nekton seen in these relatively shallow dives included large and small macrourids (genus Coryphaenoides ), shrimp (infraorder Penaeidea), Halosauropsis macrochir , Aldrovandia sp., Antimora rostrata , and alepocephalids. The last two were more characteristic of the upper areas of the slope reached by MIR 1, as it rose along the Mid-Atlantic Ridge to depths less than 3000 m. Distributions of some forms seemed associated with depth and/or the presence of hard substrate. Sessile organisms such as sponges and large cnidaria were more likely to be found in rocky areas. The second pair of dives occurred in an abyssal area and the submersibles passed over sediment-covered plains, with little relief and many fewer countable organisms and features. The most evident of these were holes, mounds, small cerianthid anemones, small macrourids and the holothurian Benthodytes sp. A few large macrourids and shrimp also were seen in these deeper dives, as well as squat lobsters ( Munidopsis sp.). Sponges and larger cnidaria were mostly associated with a few small areas of rocky substrate. Holes and mounds showed distributions suggesting large-scale patterning. Over all dives, most sessile and epifaunal forms showed clumped distributions. However, large holothurians and large nekton often had distributions not significantly different from random.

DISTRIBUIÇÃO VERTICAL NO SEDIMENTO DOS GRUPOS FUNCIONAIS DE ANELÍDEOS POLIQUETAS EM UMA ÁREA DA ENSEADA MARTEL, BAÍA DO ALMIRANTADO, ANTÁRTICA

Normal 0 21 false false false MicrosoftInternetExplorer4 st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabela normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} Studies concerning patterns of vertical stratification of macrofauna in Antarctic ecosystems are uncommon. In this paper, it was assessed the vertical distribution of polychaetes feeding guilds in Martel Inlet, Admiralty Bay in three depths: 20, 30 and 60m in five strata of two cm each up to 10cm of sedimentary column. The pattern of sedimentary variation was significant only for depth, with more fine sand and less clay amount in shallower depths (20m). Among the feeding guilds, deposit feeders were the only group that presented any relation with sedimentary variables, with higher densities in fine sand, besides a bathymetric pattern with higher densities at 20m. Discretely mobile and sessile forms also presented a noticeable bathymetric variation being the sessiles more abundant at 20m. The only guild that presented vertical stratification was discretely mobile, with decreased in number along the sedimentary column.

Staphylococcus epidermidis glucose uptake in biofilm versus planktonic cells

The aim of this work was to compare the glucose uptake of biofilms formed by four different Staphylococcus epidermidis strains as well as to compare between sessile and planktonic cells of the same strain. Biofilm cells showed a lower level of glucose uptake compared to planktonic cells. Moreover, glucose uptake by cells in the sessile form was strongly influenced by biofilm composition. Therefore, this work helps to confirm the phenotypic variability of S. epidermidis strains and the different behaviour patterns between sessile and free cells.

Finding of Pebrilla paguri (Ciliata, Folliculinidae, Heterotricha) epibiont inside the shells of two hermit crab species, Calcinus tubularis and Clibanarius erythropus (Decapoda, Anomura, Diogenidae)

Ever since its discovery, Pebrilla paguri was considered to be an exclusive epibiont of hermit crabs. In fact, up to now, it has never been recorded on substrata other than the hermit crab exoskeleton. The finding of its loricae on non‐consecutive exuviae, released by the same specimen of Calcinus tubularis, suggested that the motile stage may transform into the sessile form and attach itself to the shell occupied by the crab. All the shells occupied by the C. tubularis and Clibanarius erythropus specimens showing the ciliate on the exoskeleton were identified to genus level; for each shell genus a map of the inner morphology was drawn in order to record the position and number of the loricae. The present research showed that P. paguri is not an exclusive hermit crab epibiont: it also attaches itself to shells, and particularly to the three largest whorls, corresponding to the portion occupied by the crab body. The presence of P. paguri in the shell may be determined by the preference for substrata characterized by a particular water stream or light levels. The results obtained show that the P. paguri substrata choice is more similar to that of other folliculinids, and more varied than previously reported.

Development of ciliate community on artificial substrates associated with vertical gradients of environmental conditions in a karstic lake

The composition of ciliate communities, their abundance and biomass were studied on glass slides exposed in the epilimnion (1 m), metalimnion (9 m) and hypolimnion (18 m) in the karstic barrage Visovac Lake (SW Dinarid, Croatia). After one-month exposure periods from May 1995 to February 1996, mean ciliate biomass decreased with depth (at 1 m 54 μ g cm-2, at 9 m 37 μ g cm-2 and at 18 m 28 μ g cm-2), whereas the mean population density was relatively uniform (675 Ind. cm-2 at 1 m, 592 Ind. cm-2 at 9 m, and 678 Ind. cm-2 at 18 m). Sessile forms (peritrichs and suctorians) were dominant during all exposure periods and at all three depth layers. Omnivorous ciliates were dominant in the epilimnion, whereas in the metalimnion and hypolimnion bacterivores and carnivores were most abundant. Ciliates inhabiting artificial substrates in the epilimnion had two temporal peaks of density and biomass: in June and in October. In the deeper layers these maxima appeared one or two months later. Seasonal changes in ciliate biomass and community and trophic composition were associated with changes in thermal stratification and vertical oxygen gradients as important abiotic parameters, periphyton biomass as food source, and the tufa deposit determining the properties of substrate.

Biodiversity of freshwater rotifers (Rotifera, Eurotatoria) from North-Eastern India

A study of the rotifer communities of North-Eastern India, a global biodiversity ‘hot-spot’, reveals 188 species, comprising 53.2% of the Indian Rotifera, and reflects the highest species, generic and family richness recorded up till now from any region of this country. Cosmopolitan species (59.6%) show qualitative dominance while pantropical (14.9%) > tropicopolitan (10.6%) species are well represented. Biogeographically interesting elements (14.9%) include four Australasian, seven Oriental, ten Palaeotropical, one Holarctic species and four endemic taxa; the members of the first two categories indicate a unique affinity of the N.-E. Indian Rotifera with the faunas of South-East Asia and Australia. Lecanidae (53 species) > Brachionidae (27 species) = Lepadellidae (27 species) > Trichocercidae (17 species) > Notommatidae (13 species), together comprise a major fraction (72.8%) of the reported species. The collections examined so far from subtropical and tropical localities of N.-E. India broadly show the tropical character of the rotifer taxocoenosis. The most diverse genera, namely Lecane (28.2%) > Lepadella (11.1%) > Trichocerca (9.0%) > Brachionus (7.4%), include 105 species; the first three are predominantly littoral-periphytic taxa. Acidic to slightly acidic biotopes of different parts of N.-E. India are characterized by the occurrence of several acidophilous elements and a relative paucity of Brachionus spp. The floodplain lakes of the Brahmaputra river basin are the richest rotifer habitats known to date from the Indian subcontinent and the rice-fields also exhibit an interesting composition. Planktonic and littoral taxa are relatively abundant while sessile, colonial and bdelloid forms remain poorly examined. Maximum rotifer richness from Assam (170 species), the highest record from any state of India, is followed by reports of 116 and 112 species from Meghalaya and Tripura, respectively. Extensive collections are still needed from different states of the N. E. India region in general, and from temperate localities in particular, to update rotifer biodiversity status and to analyze latitudinal and longitudinal distribution patterns of various taxa. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Historical introduction, overview, and reproductive biology of the protochordates

This issue of the Canadian Journal of Zoology exhaustively reviews most major aspects of protochordate biology by specialists in their fields. Protochordates are members of two deuterostome phyla that are exclusively marine. The Hemichordata, with solitary enteropneusts and colonial pterobranchs, share a ciliated larva with echinoderms and appear to be closely related, but they also have many chordate-like features. The invertebrate chordates are composed of the exclusively solitary cephalochordates and the tunicates with both solitary and colonial forms. The cephalochordates are all free-swimming, but the tunicates include both sessile and free-swimming forms. Here I explore the history of research on protochordates, show how views on their relationships have changed with time, and review some of their reproductive and structural traits not included in other contributions to this special issue.

Effects of Fresh Garlic Extract on Candida albicans Biofilms

The effects of fresh garlic extract (FGE) against planktonic Candida spp. have been demonstrated in vitro and have been attributed to the action of allicin (3), a sulfur-containing compound that is formed at levels of approximately 3 to 5 mg/g of fresh clove (8). Biofilm-associated, or sessile, Candida albicans organisms demonstrate increased resistance to traditional antifungal agents that have activity against their planktonic counterparts (5). Therefore, we investigated the activity of FGE against both planktonic and sessile forms of C. albicans. (This data was presented in part at the 44th Interscience Conference on Antimicrobial Agents and Chemotherapy, Washington, D.C., 30 October to 2 November 2004.) FGE was prepared as previously described by Lemar and colleagues (7). Briefly, fresh garlic cloves were crushed in sterile saline at a concentration of 40 mg/ml. FGE was filter sterilized and stored at −70°C until use. We utilized C. albicans GDH 2346, a strain isolated from a denture stomatitis patient that is known to produce an extracellular matrix containing a mannoprotein adhesin, with a previously described method of C. albicans biofilm formation (2, 4). Sterile silicone elastomer disks were immersed in 1 × 107 CFU of C. albicans, incubated at 37°C on an orbital shaker for 90 min, and then rinsed. One-third of the disks were placed in 0, 0.5, or 1.0 mg of FGE/ml in yeast nitrogen base and incubated at 37°C for 48 h prior to evaluation. The other disks were incubated in yeast nitrogen base for 48 h to form mature biofilms. The untreated, mature biofilms were incubated with 0, 2, or 4 mg of FGE/ml in saline for 1 or 48 h prior to evaluation. All biofilms were evaluated with XTT [2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide] reduction assay, a semiquantitative, colorimetric assay of metabolic activity (2). MICs for planktonic organisms were measured using the NCCLS macrodilution method. All experiments were performed in triplicate on three different days. Comparisons between groups were performed by analysis of variance (ANOVA). P values of <0.05 were considered significant. The mean absorbances at 492 nm for disks treated immediately after adherence, mature biofilms treated for 1 h, and mature biofilms treated for 48 h are presented in Table ​Table1.1. MICs for planktonic yeast were 0.0625 to 0.125 mg/ml. TABLE 1. XTT assay results for adherent and biofilm-associated C. albicans treated with FGE These data demonstrate activity of FGE against C. albicans in its planktonic, adherent, and sessile phases. The in vitro activity decreases as the biofilm phenotype develops, as noted previously with traditional antifungal drugs (1). The superior activity at 1 versus 48 h of treatment probably relates to the half-life of FGE at 37°C and would be an important consideration in the development of in vivo uses (6). Although only one strain of C. albicans was used, the same MIC range and metabolic assay results were demonstrated with a clinical candidemia isolate (data not shown). These results appear promising and merit further investigation for determination of the antifungal activity of FGE against C. albicans biofilms.

Seasonal ‘fall out’ of sessile macro-fauna from submarine cliffs: quantification, causes and implications

Submarine cliffs are typically crowded with sessile organisms, most of which are ultimately exported downwards. Here we report a 24 month study of benthic fauna dropping from such cliffs at sites of differing cliff angle and flow rates at Lough Hyne Marine Nature Reserve, Co. Cork, Ireland. The magnitude of ‘fall out’ material collected in capture nets was highly seasonal and composed of sessile and mobile elements. Sponges, ascidians, cnidarians, polychaetes, bryozoans and barnacles dominated the sessile forms. The remainder (mobile fauna) were scavengers and predators such as asteroid echinoderms, gastropod molluscs and malacostracan crustaceans. These were probably migrants targeting fallen sessile organisms. ‘Fall out’ material (including mobile forms) increased between May and August in both years. This increase in ‘fall out’ material was correlated with wrasse abundance at the cliffs (with a one month lag period). The activities of the wrasse on the cliffs (feeding, nest building and territory defence) were considered responsible for the majority of ‘fall out’ material, with natural mortality and the activity of other large mobile organisms (e.g. crustaceans) also being implicated. Current flow rate and cliff profile were important in amount of ‘fall out’ material collected. In low current situations export of fallen material was vertical, while both horizontal and vertical export was associated with moderate to high current environments. Higher ‘fall out’ was associated with overhanging than vertical cliff surfaces. The ‘fall out’ of marine organisms in low current situations is likely to provide an important source of nutrition in close proximity to the cliff, in an otherwise impoverished soft sediment habitat. However, in high current areas material will be exported some distance from the source, with final settlement again occurring in soft sediment habitats (as current speed decreases).