Identification of two putative adhesive polypeptides in Caulerpa prolifera rhizoids using an adhesion model system

The rhizoid section of the green alga Caulerpa prolifera (Cp) is active in attaching the developing plant to the substratum. A model system for the study of the adhesion of Cp rhizoids has been developed and identification of two putative adhesive polypeptides of Caulerpa (Vn-Cp) was revealed by immunodetection. A method for fast induction of new rhizoids was established using blade-base cutting followed by a few days of incubation. The new rhizoids were gently enclosed between two cover glasses and incubated until firm attachment developed. While analyzing protein extracts, two ∼60–70 kDa polypeptides (Vn-Cp I and Vn-Cp II) were identified by immunodetection with monoclonal antibodies to human vitronectin (Vn). The relative concentration values of the Vn-Cp proteins increased significantly in the ‘cell-wall’ fraction of the attached rhizoids during the incubation period. However, Vn-Cp proteins were not detected in non-attached rhizoids. Furthermore, the Vn-Cp proteins were also detectable on glass substratum subsequent to attached rhizoid removal. The induction and accumulation of Vn-Cp proteins on the ‘cell-wall’ of Caulerpa rhizoids and the firm attachment of the rhizoids to the glass substratum during the incubation period suggest that Vn-Cp proteins play a significant role in adhesion, which may be similar to the function of vitronectin in other adhesion systems. Furthermore, the high accumulation of Vn-Cp proteins on the glass substratum during attachment of new rhizoids suggests that the Vn-Cp proteins are secreted to the extracellular matrix and directly connect rhizoids to the glass substratum as an intermediate compound. These unique properties of Cp make it an excellent model system for the establishment of high amounts of adhesive material for future research. This revised version was published online in August 2006 with corrections to the Cover Date.     

Distribution of a nematocyst-bearing sponge in relation to potential coral donors

Haliclona sp. 628 (Demospongiae, Haplosclerida, Chalinidae), a sponge found on the reef slope below 5 m depth on the Great Barrier Reef, has two unusual characteristics. It contains a symbiotic dinoflagellate, Symbiodinium sp., similar in structure to the dinoflagellate found within Acropora nobilis (S. microadriaticum), and it contains coral nematocysts randomly distributed between the ectosome and endosome and usually undischarged in intact sponge tissue. Given the unusual occurrence of nematocysts in Haliclona sp. 628, the focus of this study was to determine the distribution of this species of sponge on the reef slope at Heron Island Reef in relation to the distribution of potential coral donors. A combination of line and belt transects was used to estimate the abundance of Haliclona sp. 628 and a co-occurring congener, Haliclona sp. 1031, which does not contain nematocysts, at three widely separated sites on the reef slope at Heron Island Reef. The abundance of different types of substratum (sand, sand-covered coral rubble, dead A. nobilis, live A. nobilis, other live coral, and other dead coral) along the transects and the substratum to which each sponge colony was attached were also recorded. Despite the predominance of live A. nobilis and sand-covered rubble at all sites, between 30 and 55% of Haliclona sp. 628 colonies were attached to dead A. nobilis which comprised less than 8% of the available substratum along any transect. In contrast, Haliclona sp. 1031 was found significantly more frequently on other dead corals and less frequently on live A. nobilis than would be expected based on the availability of the different substrata in the sites. Potential explanations to account for the distribution of Haliclona sp. 628 in relation to potential coral donors are discussed.     

Echinophycus minutus (Rhodomelaceae, Ceramiales), a new red algal genus and species from north-western Australia

Echinophycus minutus gen. et sp. nov. (Ceramiales, Rhodophyta) is described for specimens collected from a deep‐water habitat in the Dampier Archipelago, northwestern Australia. Plants were dredged from a coarse sand/rubble habitat, where they were partially decumbent and attached to the substratum by numerous unicellular rhizoids, Thalli are to 25 mm in height, uniaxial, with four pericentral cells and a persistent pigmented trichoblast arising on each axial cell. Tricho‐blasts are arranged in a spiral pattern, with a 90° divergence between successive segments. Each trichoblast is composed of a basal cell bearing a cluster of unbranched filaments. Tetrasporangia are tetrahedral and formed in series in normal branches. Procarps have two sterile cell groups. Spermatangia are formed In heads that are terminal on trichoblasts. The new genus is placed in the tribe Brongniartelleae of the family Rhodomelaceae, differing from all other included genera in the morphology of the trichoblasts.     

Colony–Substratum Relations in Scrupocellariidae (Bryozoa, Cheilostomata)

In the Bryozoa in general the colony is attached by means of the primary zooid, the ancestrula, which is permanently cemented to the substratum. The attachment is brought about, in the marine bryozoans, by the larva everting its interior sac into a basal adhesive disc secreting a thin layer of hardening mucus. In Scrupocellaria reptans no adhesive disc was found. The metamorphosing larva is fixed to the substratum by a column of loose, sticky secretion. This primary fixation is ephemeral and replaced by a secondary, permanent fixation by one pair of rootlets. Thus, the ancestrula body proper and the colony arising from it become permanently free from the substratum but anchored to it by rootlets, the primary pair and series of secondary rootlets. This unique and certainly secondarily evolved type of attachment is apparently realized in the Scrupocellariidae in general, to a more or less perfect degree. It appears as one of several possible models to meet efficiently with environmental disturbances.     

Intrinsic factors influence the attachment of fragments of the green alga Caulerpa filiformis

Asexual reproduction via fragmentation is an integral component of the life history of many marine organisms. In south-eastern Australia the green macroalga Caulerpa filiformis (Suhr) Hering is abundant on many rocky shorelines and fragments are very abundant in the water column. We examined some of the factors that may influence the growth and successful reattachment of fragments of C. filiformis that potentially contribute to its success. Field surveys revealed that C. filiformis fragments were of variable morphologies (from small fronds to entire thalli) and sizes (0.1-60 cm in length). All fragments of C. filiformis were viable propagules that survived and grew well in the laboratory. However, some fragments grew more than others, in particular larger sizes (7.5 cm class) of certain morphologies (fragments that consisted only of a single frond). Rhizoids were produced by all fragments, but again, larger fragments produced more rhizoids than smaller fragments. The force required to detach fragments was proportional to the number (but not size) of rhizoids, demonstrating the importance of rhizoids for attachment. The rate of attachment of fragments was also fast, usually within 12 h, but the longer these fragments were attached to a substratum the greater the force required to dislodge them. Interestingly, fragments only produced rhizoids if they were resting on a substratum which may explain the small proportion of fragments with rhizoids in the field (< 5%). Ultimately, the long term success of C. filiformis fragments was low as only 1.6% of fragments attached within 24 h and none of these persisted for longer than 2 days. Nonetheless, the abundance and viability of fragments of C. filiformis available to attach suggest that asexual fragmentation is a successful reproductive strategy in this seaweed.     

Limited period of graviresponsiveness in germinating spores of Ceratopteris richardii

Rhizoids of the fern Ceratopteris richardii Brogn. usually emerge 40 h after germination is initiated by light, and more than 90% of them emerge growing in a downward direction. However, when the spores are germinated on a clinostat, the emerging rhizoids show no preferential orientation. This indicates that under normal 1 · g conditions the initial growth direction of rhizoids can be oriented by gravity. If the orientation of the spores is changed 3 h or less after the start of germination, the growth direction of most emerging rhizoids becomes downward relative to the new orientation. However, if the orientation of the spores is changed by 180° 8 h or more after germination is initiated by light, most rhizoids emerge growing upward; i.e., the same direction as if there had been no orientation change. Emerged rhizoids also do not change their direction of growth if their orientation is changed. These results indicate that the growth direction of emerging rhizoids is set by gravity prior to actual emergence, and that the time of full orientation responsiveness is limited to a period ranging from the initiation of germination to about 3–4 h after the start of germination. There is a gravity-oriented nuclear movement beginning at about 13 h after germination, and this movement appears to predict the initial growth direction of rhizoids.These studies were made possible by grant NAGW 1519 to S.J.R. and grant NGT-51065 to E.S.E., both from the National Aeronautics and Space Administration.     

GERMINATION AND ATTACHMENT OF ZYGOTES OF HIMANTHALIA ELONGATA (L.) S. F. GRAY1

Germinating zygotes of Himanthalia elongata (L.) S. F. Gray have a prolonged stage free from rhizoids. The spherical zygote flattens when settling on a substratum and a rim-like structure develops at the periphery of the flattened base. Numerous rhizoids appear simultaneously 5–7 days after fertilization. The possible significance of the germling's shape and structure in relation to attachment is discussed.     

Proliferation of epithelial cells derived from rat dorsolateral prostate in serum-free primary cell culture and their response to androgen

Summary Primary cultured epithelial cells derived from the rat dorsolateral prostate proliferated in serum-free nutrient medium WAJC 404 supplemented with mitogens: insulin (650 nM), cholera toxin (120 pM), epidermal growth factor (EGF) (2.5 nM), dexamethasone (300 nM), and bovine pituitary extract (25 μg/ml). The culture consisted of two types of epithelial cell colonies: one originated from single cells or small cell aggregates and the other was epithelial cell outgrowth from small tissue fragments attached to a substratum. There were differences in requirements for the mitogens between the two types of colonies. Requirements for cholera toxin, bovine pituitary extract, and dexamethasone were higher in the former type of colonies, and those for EGF were higher in the latter type of colonies. Proliferation of the epithelial cells in either type, of colony was suppressed more than 50% by 1 nM dihydrotestosterone. This suppressive effect was not mediated by stromal component in the tissue fragments, and was counteracted by cyproterone acetate, indicating specific and direct action of the androgen on prostate epithelial cells. The results suggest that there is discrete participation of polypeptide growth factors and androgen in proliferation and differentiation, respectively, of prostate epithelial cells in vivo.     

Passive colonization and asexual colony multiplication in the massive coral Porites lutea Milne Edwards & Haime

Heads of the reef-building coral Porites lutea Milne Edwards & Haime are occasionally separated or torn loose from the substratum by bioerosion or mechanical stresses. Detached heads may survive and colonize down-slope or down-stream soft bottoms, forming incipient reefs in habitats unsuitable for colonization by larval settlement. One important result of this process is reef consolidation and growth on the lagoonward edge of truncated, inter-island reef flats on atolls. In some cases, portions of the detached colonies remain attached at the original site; thus there is asexual colony multiplication.     

Habitat use by Mountain Plovers in prairie dog colonies in northeastern New Mexico

ABSTRACT Mountain Plovers (Charadrius montanus) are grassland birds that often breed in close association with colonies of black‐tailed prairie dogs (Cynomys ludovicianus). However, not all colonies provide plover nesting habitat or habitat of equal quality, and the characteristics of colonies important for plovers remain poorly understood. Over two years, I used plover distribution surveys, territory mapping, and habitat sampling to study habitat use by plovers in prairie dog colonies in shortgrass prairie in northeastern New Mexico. My objective was to document important components of plover breeding habitat in colonies by comparing characteristics of used and unused habitats at three spatial scales: colony, territory, and nest‐site. I found evidence of plover breeding in 14 of 44 colonies in 2009 and 13 of 43 colonies in 2010. Based on logistic regression, the probability of a colony being occupied by plovers was positively associated with colony size, but negatively associated with mean vegetation height. Preference for larger colonies could relate to minimum habitat requirements, or a potential tendency of this species to nest in social clusters. Shorter vegetation height was strongly correlated with greater bare ground and lower forb/subshrub cover, all characteristics that may be related to plover predator avoidance and foraging microhabitat. At both the territory and nest‐site scale, areas used by plovers had shorter vegetation, more bare ground, and less forb/subshrub cover than unused areas. Nest sites were also more sloped, perhaps to reduce risk of flooding, and located further away from the nearest prairie dog burrow, perhaps to reduce risk of disturbance. Overall, my results show that plover use of prairie dog colonies was influenced by landscape and habitat features of colonies, and suggest that large colonies are particularly valuable because they are most likely to contain adequate areas with preferred habitat characteristics.     

Biomechanical properties and holdfast morphology of coenocytic algae (Halimedales, Chlorophyta) in Bocas del Toro, Panama

For attached marine organisms, specific biomechanical properties may result in detachment or in tissue loss, when sufficient tensile force is applied. Algae experience such forces through water movement, which may thus act to limit size, abundance, and species composition, of populations of algae.Coenocytic construction is uncommon in the algae, but it occurs relatively more frequently in green algae found in shallow subtidal sediments associated with coral reefs, e.g., at our study site of Isla Colon, Bocas del Toro, Panama. We studied the biomechanical properties of some tropical coenocytic algae (Udotea flabellum (Ellis et Solander) Lamouroux, Penicillus capitatus Lamarck, P. pyriformis A. and E.S. Gepp, and Halimeda gracilis Harvey) anchored in sediments. We compare our results with published data on other coenocytic algae, as well as with multicellular algae. Our results show that properties of sand-dwelling coenocytes, such as mean force to dislodge (4.9-12.7 N), mean force to break (6.6-22.1 N), and mean strength (1.0-7.0 MN m^− 2), are all within the range reported for temperate, multicellular, algae. In contrast, the coenocytes differed markedly from the temperate non-coenocytes in the consequences of applied tensile force: coenocytes were removed whole, while most temperate algae attached to rocks break within the thallus. Some multicellular algae can regrow from tissue left on the substratum; three of the four coenocytic species we examined had rhizoids connecting closely adjacent (0.1-0.15 m) individuals, and these rhizoids may serve to regrow a new individual. While our experiments indicated that sufficient tensile force results in dislodgment, calculations using the experimentally determined variables led us to conclude that water velocities sufficient to dislodge individuals are unlikely to occur. Since dislodgment is usually fatal for algae, the role of the holdfast is a critical one. All of the species we investigated had similar holdfast morphology, a mass of rhizoids which entrained sand, the entire unit forming a hemispherical to cylindrical mass. Despite the consistency in holdfast form, and the initial prediction that this was an optimal form for anchoring these algae, our data suggest that this is not the case.     

Dispersal flight and colony development in the fungus-growing termites <Emphasis Type="Italic">Pseudacanthotermes spiniger</Emphasis> and <Emphasis Type="Italic">P. militaris</Emphasis>

Pseudacanthotermes spiniger and P. militaris are two African fungus-growing termites (Termitidae, Macrotermitinae) which may become pests in disturbed agrosystems where they often live in sympatry. To study their development and their reproductive strategies, colonies of both species were reared in the laboratory for 20 and 17 years, respectively, after their foundation from reproductive pairs. The first steps of development were in great part similar in both species, although P. spiniger favoured the defence during the juvenile period, while P. militaris tended to favour a rapid development. While P. spiniger colonies did not produce alates until year 7 of colony life, P. militaris colonies were able to produce a fertile progeny 4 years after their foundation. In contrast, major soldiers were more rapidly differentiated in the incipient colonies of P. spiniger. Dispersal flights occurred every year for 10 years in P. spiniger. In P. militaris, dispersal flights did not occur regularly although alates appeared yearly. The annual number of alates produced by P. spiniger increased with the colony age to reach a maximum of 25,000 individuals and global production of alates was estimated at ca. 150,000 individuals in the life of a colony. The longevity of P. spiniger and P. militaris colonies was around 20 years. These species were shown to be reproductively isolated by multiple pre-mating mechanisms. While chronological differences in dispersal flights contribute to reproductive isolation of the two species, the non-viability of experimental hybrid colonies also indicates the involvement of post-mating mechanisms of isolation.     

Colony size,nestmate density and social history shape behavioural variation in Formica fusca colonies

In ants, individuals live in tightly integrated units (colonies) and work collectively for its success. In such groups, stable intraspecific variation in behaviour within or across contexts (personality) can occur at two levels: individuals and colonies. This paper examines how colony size and nestmate density influence the collective exploratory behaviour of Formica fusca (Hymenoptera: Formicidae), in the laboratory. The housing conditions of the colonies were manipulated to vary the size of colonies and their densities under a fully factorial design. The results demonstrate the presence of colony behavioural repeatability in this species, and contrary to our expectations, colonies were more explorative on average when they were kept at lower nestmate densities. We also found that experimental colonies created from larger source colonies were more explorative, which conveys that a thorough understanding of the contemporary behaviour of a colony may require knowing its social history and how it was formed. Our results also convey that the colony size and nestmate density can have significant effects on the exploratory behaviour of ant colonies.     

THE ROLE OF UNICELLS IN THE POLYMORPHIC SCENEDESMUS ARMATUS (CHLOROPHYCEAE)1

The UTEX 2193 strain of Scenedesmus armatus (Chod.) Chod, when cultured in any of several media (whether natural or artificial, concentrated or dilute) produced a variety of colonial morphologies as well as a unicell population. Morphological expression was related to culture ape. When the initial cell density was just a feu1 hundred cells per mL. the culture first produced a unicell population, then spiny colonies, and as stationary phase was approached, spine-less colonies. Two classes of spiny colonies were detected. Type I colonies had elongate cells with the terminal cells shorter than median cells. Spines were longer than cell length. The wider, oval, grainy cells of Type II colonies were uniform m length. Spines were shorter and thicker than those on Type I colonies. Only Type I colonies produced unicells: the latter appeared as two morphs. The smaller unicell was obovoid with four delicate spines: the larger had ovate cells bearing four thicker spines. Control of unicell development in all media was achieved by carefully monitoring colony type and cell number used for the inoculum. A unicellular population developed in batch culture in defined media, both concentrated and dilute, when the initial cell density (either Type I or Type II colonies) was low (below 1000 cells-mL^?1), as well as in synchronous cultures. With higher initial cell densities, e.g. 2 × 10⁴ cells·mL^?1, the inoculum had to contain Type I colonies to produce unicells. Unicells were also produced in water from Agronomy Pond, where the strain originated. We discuss the role of unicell populations in the distribution of Scenedesmus.     

Colony Structure in Flustra foliacea (Linnaeus) (Bryozoa,Chéilostomata)

Encrusting forms presumably represent the original mode of growth in the bryozoans. They usually exhibit a relatively low degree of colony integration. The numerous different erect colony types, certainly independently derived from this stage, show a higher degree of integration. Eventually forms arise with a strict pattern only little influenced by the environment. The Flustra foliacea colony holds an intermediate position in this respect. It forms an initial crust on a foreign substratum such as rock. The crust forms marginal lobes. The lobes collide two and two. The two components of each collision then rise back to back, owing to lack of space, into bilaminar fronds. The two zooid layers composing these erect branches and mutually encrusting the “auto-substratum” of their respective basal walls, grow much more rapidly than the initial crust on the “heterosubstratum” of the rock to finally comprise more than 95 % of the colony volume. The different rate of growth on “auto-” and “heterosubstratum” respectively is interpreted as indicating a preference for the “autosubstratum” and as the main force in the formation of erect branches. The Fl. foliacea case indicates one of the pathways from encrusting to erect colonies in the bryozoans. It is probably valid for at least some of the erect bilaminar colonies appearing in different parts of the bryozoan system.     

Behavior of unacquaintedSaimiri troops upon encounter: A suggestive case study

When primate societies merge, the probabilities of genetic combinations are altered. What occurs when previously unacquainted groups meet is a product of the social organization of the species and a major contributor to genetic variance. Two colonies ofSaimiri sciureus that had lived independently for five to seven years were permitted to meet. One colony was subjected to injurious aggression by a second colony. We suggest that the demographic characteristics of the groups are suggestive determinants of the acceptance or rejection of unfamiliarSaimiri.     

Coral reefs in the Southern Barents Sea: habitat description and the effects of bottom fishing

Fifteen Lophelia reefs from offshore to coastal areas off northern Norway were studied using video. Health status of the coral habitat (degree of physical impact, % cover of living tissue, colony size), occurrence of trawl marks and lost fishing gear, height of coral colonies and associated fauna were analysed from 44 video-lines. Fishing impact was more frequent on the offshore reefs (36.5% of the observed areas) than those in the coastal reefs (0.6%). The most visible effects of fishing were broken and displaced coral colonies. At some sites only small scattered fragments of live corals were observed, indicating recent impact. The mean colony height of Lophelia and gorgonian corals at impacted sites was around half the size of those at non-impacted sites. Both species richness and abundance was higher at non-impacted coral habitats compared to impacted. The actinarian Protanthea simplex and unidentified brittlestars were the only taxa with higher abundance on impacted compared with non-impacted habitats. The reefs at the offshore location were protected against bottom trawling in 2009 through the establishment of a marine protected area (MPA), but a general ban against trawling on known coral reefs had already been implemented in 1999. In the MPA, signs of regrowth were observed. Most of the observed damage probably occurred over 10 years earlier. Results show that live and non-impacted cold water coral reefs have an important ecological function by enhancing the local biodiversity and fish abundance. Preventing further damage to impacted reefs may lead to full recovery within a few decades.     

Receptor-mediated formation of multilayer aggregates of primary cultured adult rat hepatocytes on lactose-substituted polystyrene.

We used a lactose-substituted polystyrene, poly-N-p-vinylbenzyl-D-lactonamide (PVLA), as a substratum for adult rat hepatocytes in primary culture. Spherical-shaped hepatocytes attached on PVLA substratum formed stable multilayer aggregates anchored on substratum through the stimulation of epidermal growth factor (EGF). The cells required calcium ion essentially to form the aggregates. The formation of multilayer aggregates was inhibited by colchicine, but not by cytochalasin B. The inhibition was also observed by added PVLA molecules in the culture medium and by treating surfaces of PVLA-coated dishes with allo A lectin. It was suggested that adult rat hepatocytes attached on PVLA substratum required the specific interaction between asialoglycoprotein receptors on the cell surface and PVLA substratum to form anchored multilayer aggregates.     

Galvanic Stimulation of Volvox globator I. Electroosmotic Patterns Associated with the Ion Exchange Properties.

Application of direct electric potentials across immobilized Volvox globator colonies produced patterns in the ambient solution that were observable by dark field microscopy by the use of polystyrene spheres in the medium. Two large elliptical swirls occurred immediately adjacent to the colony nearest the anode. A clear area developed outwards from the cathodal side of the colony. Since similar patterns were obtained with live, dead, and deflagellated colonies, it was assumed that the phenomena were purely physical. The electric potential induced an electroosmosis in the glass stimulation chamber. Live or dead colonies, immobilized by being secured with a glass coverslip, experienced an anodal movement of water and associated polystyrene spheres. The electroosmosis gave rise to solution patterns which were shown not to be the result of hydrostatic pressure (turbulence) or thermal convection currents. When anion-exchange beads were substituted for colonies in the stimulation chamber, application of the electric potential produced a smooth laminar flow around the positively charged beads. Cation-exchange beads, on the other hand, produced 2 large anodal swirl patterns. Clearly, the colony surface behaved like a weakly charged cation exchanger. Other investigators have determined that the cell walls of pond water plants and algae are negatively charged and have ion-exchange abilities. The negatively charged Volvox cell wall caused an electroosmosis in the colony, in the cathodal direction. Previous explanations for the galvanotaxis of Volvox are not adequate because they do not take into account the negatively charged cell wall.     

The effect of substratum type,orientation and depth on the development of bacterial deep-sea biofilm communities grown on artificial substrata deployed in the Eastern Mediterranean

An increasing number of deep-sea studies have highlighted the importance of deep-sea biofouling, especially in relation to the protection of deep-sea instruments. In this study, the microbial communities developed on different substrata (titanium, aluminum, limestone, shale and neutrino telescope glass) exposed for 155 days at different depths (1500 m, 2500 m, 3500 m and 4500 m) and positions (vertical and horizontal) in the Eastern Mediterranean Deep Sea were compared. Replicated biofilm samples were analyzed using a Terminal Restriction Fragment Length Polymorphisms (T-RFLP) method. The restriction enzymes CfoI and RsaI produced similar total numbers (94, 93) of different T-RFLP peaks (T-RFs) along the vertical transect. In contrast, the mean total T-RF number between each sample according to substratum type and depth was higher in more samples when CfoI was used. The total species richness (S) of the bacterial communities differed significantly between the substrata, and depended on the orientation of each substratum within one depth and throughout the water column (ANOVA). T-RFLP analyses using the Jaccard similarity index showed that within one depth layer, the composition of microbial communities on different substrata was different and highly altered among communities developed on the same substratum but exposed to fouling at different depths. Based on Multidimensional Scaling Analyses (MDS), the study suggests that depth plays an important role in the composition of deep-sea biofouling communities, while substratum type and orientation of substrata throughout the water column are less important. To the authors’ knowledge, this is the first study of biofilm development in deep waters, in relation to the effects of substratum type, orientation and depth.