Oral Fimbriae and Papillae in Parasitic Lampreys (Petromyzontiformes)

There are 38 species of living lampreys, 18 parasitic and 20 nonparasitic. The parasitic species feed as adults, while the nonparasitic do not. The taxonomy and systematics of the living lampreys is based primarily on dentition characters. Since the number of oral fimbriae and oral papillae have never been systematically investigated in lampreys, we compared them in 17 of the 18 parasitic lampreys to assess their usefulness as taxonomic characters. Both showed little variation with total length and sex within a species, while exhibiting greater variation between species. Parasitic species belonging to the three lamprey families could be distinguished using the number of oral fimbriae: southern hemisphere Mordaciidae (0) and Geotriidae (55–65) and northern hemisphere Petromyzontidae (81–144). However, the taxonomic usefulness of the two characters at the species level was limited. Ten out of the 17 species of parasitic lampreys were placed into four distinct groups based on their numbers of oral fimbriae, and only in two of these was the character diagnostic. Twelve out of the 17 species were placed into two distinct groups based on their numbers of oral papillae and for none of these was the character diagnostic. Blood feeders and intermediate feeders (blood + flesh) were shown to have significantly higher numbers of oral fimbriae than flesh feeders. The higher numbers of oral fimbriae in the former two types of feeders were presumed to be linked to their greater need to create a good seal for feeding purposes. Blood feeders were also shown to have significantly higher numbers of oral papillae than either intermediates or flesh feeders. The higher numbers of oral papillae in the blood feeders were presumed to be linked to their greater need to find suitable attachment sites for feeding purposes.     

Oral papillae of adults of the southern hemisphere lamprey Geotria australis

The morphology, cell types, and innervation of the several small papillae (x? = 17) and two larger papillae, which together form a ring just outside the fimbriae surrounding the suctorial disc of adult Geotria australis, have been studied using various histological stains, including silver impregnation, and scanning and transmission electron microscopy. The epithelium of all papillae consists almost entirely of mucigenic cells. The multivillous and oligovillous cells, which are found elsewhere in the lamprey epidermis, were not observed, and Merkel and polyvillous cells are rare. Free nerve endings are common, however, in the basal layers of the epidermis. Unlike the small papillae, the two large papillae contain a core of skeletal muscle and a prominent layer of dermal collagen. In the submucosa of these large papillae, the nerves form a dense, compact layer that contains many large and probably sensory axons. It is suggested that the oral disc papillae of adult G. australis are encapsulated mechanosensory structures that play a role in enabling the animal to locate and attach to a suitable point on host fishes or other surfaces.     

Metamorphosis of the mountain brook lamprey Ichthyomyzon greeleyi

Synopsis Metamorphosis of the nonparasitic mountain brook lamprey, I. greeleyi, is described within 7 phases based on external morphological changes. The commencement of metamorphosis in early August is consistent with the pattern for northern hemisphere lampreys which display an inverse relationship with latitude. The sequence of external changes including the development of eyes, oral disc, teeth, tongue, oral fimbriae and lateral line its consistent among individuals of I. greeleyi and lampreys in general. Some of the changes realized during metamorphosis of I. greeleyi are important to the adult period while others reflect their presumed parasitic ancestry. Energy reserves by nonfeeding I. greeleyi during the 104–140 days required to complete metamorphosis are replaced by water so that total length and body weight do not change significantly during this time.     

Incidence of lamprey marks on Lake Sturgeon (Acipenser fulvescens Rafinesque, 1817) in the St. Clair – Detroit River System: Implications for Sea Lamprey (Petromyzon marinus Linnaeus, 1758) effects

Laurentian Great Lakes Lake Sturgeon (Acipenser fulvescens) are hosts to lamprey species, including native Silver Lamprey (Ichthyomyzon unicuspis) and invasive Sea Lamprey (Petromyzon marinus). Silver Lamprey coevolved with Lake Sturgeon and cause negligible mortality, but Sea Lamprey can negatively affect Lake Sturgeon populations. Sea Lamprey abundance in Lake Erie has been above targets set by resource managers, with the St. Clair – Detroit River System (SCDRS) suspected as a source of Sea Lamprey production into Lake Erie. This study summarizes lamprey marking on Lake Sturgeon captured during agency assessment surveys in the SCDRS since 1996 and provides insight on the potential for Sea Lamprey to negatively affect Lake Sturgeon in the SCDRS. Lamprey marks (any lamprey species) were noted on 48.2% of Lake Sturgeon (2.5 marks/fish) and 3.3% of Lake Sturgeon assumed to be susceptible to mortality by Sea Lamprey (<760 mm TL; 0.06 marks/fish). Silver Lamprey were the only lamprey species found attached to Lake Sturgeon and there was no difference between oral disc diameters of Silver Lamprey and marks measured on Lake Sturgeon in Lake St. Clair and the lower St. Clair River (p = .45). Based on logistic regression, probability of at least one lamprey mark increased with Lake Sturgeon total length and was highest in Lake St. Clair. The probability of observing at least one lamprey mark on a 760 mm Lake Sturgeon was 8.1% or less for each sampling location in the SCDRS aside from Lake St. Clair (28.1%). Results suggest that parasitism of Lake Sturgeon by Sea Lamprey in the SCDRS is rare, particularly for Lake Sturgeon <760 mm TL. Low incidence of lamprey marks on Lake Sturgeon assumed to be susceptible to mortality from Sea Lamprey parasitism and zero occurrence of Sea Lamprey being observed attached to a Lake Sturgeon suggest Sea Lamprey at their current abundance likely have little effect on the Lake Sturgeon population in the SCDRS. Caution should be taken when using mark size to assign marks to lamprey species as there is substantial overlap among species oral disc diameters, potentially inflating the perceived impact of Sea Lamprey on Lake Sturgeon in areas with native lampreys.     

Distribution of growth hormone-like cells in the pituitary of adult sea lampreys,Petromyzon marinus

Growth hormone (GH), prolactin (PRL) and somatolactin (SL) are members of a pituitary hormone family that are believed to have evolved from a common ancestral gene by duplication and subsequent divergence. Since these hormones are found both in bony fish and cartilaginous fish, their ancestral form(s) should be present in the Agnatha. Thus, although there is no convincing evidence that the lamprey pituitary secretes GH or PRL, GH- and/or PRL-like immunoreactivity was examined in the pituitary of adult sea lampreys (Petromyzon marinus), using antibodies to GHs, PRLs and SL of mammalian and/or fish origins. Our initial attempt with ordinary immunohistochemical procedures failed to detect any positive reactions in the lamprey pituitary. Following the hydrated autoclave pretreatment of the sections, anti-salmon GH, anti-salmon PRL and anti-blue shark GH gave positive reactions in most cells distributed in the dorsal half of the proximal pars distalis. These results suggest that the material immunoreactive to those antibodies is related, to some extent, to GH/PRL, but enhancement of immunoreactivity to reveal this by the hydrated autoclave pretreatment of sections is needed due to low crossreactivity. The similarity of the topographic distributions within the pituitary between lampreys and teleosts suggests that lamprey GH/PRL-like cells are GH cells of the lamprey.     

The Dentition and Feeding Mechanism in Adults of the Southern Hemisphere Lamprey Geotria australis Gray

Scanning electron micrographs of the teeth and sections and dissections of the head have been used to describe the functional interrelationships between the dentition and associated cartilages, muscles and ligaments in adults of the southern hemisphere lamprey Geotria australis. These studies, together with manipulation of the piston and oral disc in living specimens, elucidated the probable feeding mechanism in this species. The main cutting action appears to result from a scissoring movement brought about by the rapid interlocking of the three sharp and stout cusps of the transverse lingual lamina with large grooves on the rear face of the supraoral lamina. The movement of excised flesh back through the oral passage to the pharynx would be facilitated by the action of the pair of strongly cuspid longitudinal lingual laminae. The unique oral disc teeth of G. australis are apparently adapted to allow the disc to slide forward over the host and yet restrict any tendency to slip backwards.     

Effects of texture on surface attachment of spawning‐run sea lampreys Petromyzon marinus: a quantitative analysis

Adult sea lamprey Petromyzon marinus attachment strength by the oral sucker was quantified. Surfaces with shallow, rounded discontinuities into which the oral fimbriae could be folded yielded the strongest seal and some fish could control their mouths to improve ‘suction’. Narrow grooves of 1 mm width and 3 mm depth prevented P. marinus from creating a lasting attachment.     

Metamorphosis in the paired species of lampreys, Lampetra fluviatilis (L.) and Lampetra planeri (Bloch): 2. Quantitative data for body proportions, weights, lengths and sex ratios

Representatives of the various Stages (1–9) in the metamorphosis and short adult life of the brook lamprey, Lampetra planeri , were used to provide quantitative data to describe the pattern of changes that take place during this period of the life cycle. During the transformation of the oral hood into an oral disc, this ventral region of the snout first declines in length before increasing markedly. The branchial region declines in length and remains relatively smaller than in the ammocoete, a feature probably correlated with the concomitant internal changes in the pharynx which permit a change from a unidirectional to a tidal respiratory flow. The eye increases in size only through the initial Stages (1–5). The main period of fin enlargement occurs rather later in metamorphosis than the above changes.
During maturation the two initially separate dorsal fins increase further in height and eventually become separated only by a notch. Differences between the two sexes are found in the relative size of the disc and fins, the larger structures of the male probably being related to their greater activity in spawning behaviour. Measurements on metamorphosed L. fluviatilis confirm that in this species the eye and disc are relatively larger than in L. planeri. Data are presented which illustrate that in collections taken during the metamorphosis of both species the males are smaller and slightly more numerous than the females and that transformation is initiated at a longer length in L. planeri than in L. fluviatilis .     

Inhibitory effects of Porphyromonas gingivalis fimbriae on interactions between extracellular matrix proteins and cellular integrins

Porphyromonas gingivalis is a predominant periodontal pathogen, whose fimbriae are considered to be a major virulence factor, especially for bacterial adherence and invasion of host cells. In the present study, we investigated the influence of fimbriae on the interactions between alphavbeta3- and alpha5beta1-integrins and their ligand extracellular matrix (ECM) proteins (vitronectin and fibronectin), using human alphavbeta3- and alpha5beta1-integrin-overexpressing CHO cell lines (CHOalphavbeta3 and CHOalpha5beta1, respectively). P. gingivalis was found to have significantly greater binding to CHOalphavbeta3 and CHOalpha5beta1 than to control cells, whereas a fimbria-deficient mutant showed negligible binding to any of the tested cell lines. CHOalphavbeta3 and CHOalpha5beta1 cells attached to the polystyrene culture dishes in the presence of their ligand ECM proteins, while fimbriae markedly inhibited those attachments in a dose-dependent manner, with the highest dose of fimbriae achieving complete inhibition. In addition, the binding of vitronectin and fibronectin to CHOalphavbeta3 and CHOalpha5beta1 was inhibited by P. gingivalis cells. These results suggest that P. gingivalis fimbriae compete with ECM proteins for alphavbeta3- and alpha5beta1-integrins, and inhibit integrin/ECM protein-related cellular functions.     

Buccal glands of adults of the lamprey Mordacia mordax,including comparisons with other species

Mordacia mordax is one of the two anadromous parasitic lamprey species of the southern hemisphere family Mordaciidae. Its adults possess two lateral buccal glands and one central buccal gland. When the tongue-like piston is retracted, the buccal glands occupy much of the opening of the oral cavity at the rear of the buccal cavity. The glands contain numerous tube-like, ductless secretory units, which discharge directly into the buccal cavity. Their secretory epithelial cells contain numerous granules, some of which are zymogen-like, while others have a beaded, spiralled appearance. The similarity of the latter to mast cell granules suggests that they may likewise produce an anticoagulant, which would be valuable to a presumed blood feeder such as M. mordax. The mucus produced by these cells could act as a carrier for the secretions and as an adhesive for promoting retention of t he secretions on the host's surface. When the young adults is transferred to salt water, the buccal glands increase their production and discharge of secretions. Since the glands are not enclosed in musculature, their secretions are probably discharged by mechanical pressure applied by the forward movement of the head of the tooth-bearing piston into the buccal cavity. An account is given of the way in which the location, number, glandular organization, secretory granules, and type of secretion of the buccal glands of M. mordax, and thus presumably also their mode of function, differ markedly from those of members of the other lamprey family found in the southern hemisphere, and of all holarrctic lampreys. © 1995 Wiley-Liss, Inc.     

A Reporter Assay in Lamprey Embryos Reveals Both Functional Conservation and Elaboration of Vertebrate Enhancers

The sea lamprey is an important model organism for investigating the evolutionary origins of vertebrates. As more vertebrate genome sequences are obtained, evolutionary developmental biologists are becoming increasingly able to identify putative gene regulatory elements across the breadth of the vertebrate taxa. The identification of these regions makes it possible to address how changes at the genomic level have led to changes in developmental gene regulatory networks and ultimately to the evolution of morphological diversity. Comparative genomics approaches using sea lamprey have already predicted a number of such regulatory elements in the lamprey genome. Functional characterisation of these sequences and other similar elements requires efficient reporter assays in lamprey. In this report, we describe the development of a transient transgenesis method for lamprey embryos. Focusing on conserved non-coding elements (CNEs), we use this method to investigate their functional conservation across the vertebrate subphylum. We find instances of both functional conservation and lineage-specific functional evolution of CNEs across vertebrates, emphasising the utility of functionally testing homologous CNEs in their host species.     

Sortase-catalyzed assembly of distinct heteromeric fimbriae in Actinomyces naeslundii

Two types of adhesive fimbriae are expressed by Actinomyces; however, the architecture and the mechanism of assembly of these structures remain poorly understood. In this study we characterized two fimbrial gene clusters present in the genome of Actinomyces naeslundii strain MG-1. By using immunoelectron microscopy and biochemical analysis, we showed that the fimQ-fimP-srtC1-fimR gene cluster encodes a fimbrial structure (designated type 1) that contains a major subunit, FimP, forming the shaft and a minor subunit, FimQ, located primarily at the tip. Similarly, the fimB-fimA-srtC2 gene cluster encodes a distinct fimbrial structure (designated type 2) composed of a shaft protein, FimA, and a tip protein, FimB. By using allelic exchange, we constructed an in-frame deletion mutant that lacks the SrtC2 sortase. This mutant produces abundant type 1 fimbriae and expresses the monomeric FimA and FimB proteins, but it does not assemble type 2 fimbriae. Thus, SrtC2 is a fimbria-specific sortase that is essential for assembly of the type 2 fimbriae. Together, our experiments pave the way for several lines of molecular investigation that are necessary to elucidate the fimbrial assembly pathways in Actinomyces and their function in the pathogenesis of different biofilm-related oral diseases.     

Fine structure and immunocytochemistry of cells within the endocrine pancreas of larval and adult sea lampreys, Petromyzon marinus L

Immunocytochemistry with protein A-gold and routine electron microscopy were used to identify cell types within the endocrine pancreas of larvae, juvenile adults, and upstream-migrant adults of the sea lamprey, Petromyzon marinus. The larval pancreatic islets are composed only of insulin-immunoreactive B-cells, which are uniform in their fine structure. The cranial and caudal pancreatic tissue in both adult periods contains three cell types: B-cells, somatostatin-immunoreactive D-cells, and a third cell type of unknown content. No glucagon-immunoreactive cells are present in lampreys, but B- and D-cells exist in equal numbers in the pancreatic tissue of adults. The B-cells of adults have a fine structure similar to those in larvae. D-cells have secretory granules that are distinctly different from those both in B-cells and in the third cell type. Although B- and D-cells in lamprey pancreatic tissues have a basic morphological similarity to these cells in other vertebrates, their granules are generally of smaller dimensions. The inclusion of granules within large pleomorphic bodies in many D-cells indicates that granule turnover is common. Immunocytochemistry will be a useful tool for showing the relationship between the cells in the degenerating bile ducts and those of the developing adult pancreas.     

Actin-related intercellular adhesion junctions in the germinal compartment of the testis in the hagfish (Eptatretus stouti) and lamprey (Lampetra tridentatus)

The germinal epithelium of male vertebrates consists of Sertoli cells and spermatogenic cells. Intercellular junctions formed by Sertoli cells assume critical roles in the normal functions of this epithelium. While Sertoli cell junctions have been well characterized in mammals, similar junctions in nonmammalian vertebrates have received little attention. We examined the intercellular junctions found within the germinal epithelium of the hagfish (Eptatretus stouti) and lamprey (Lampetra tridentatus). Ultrastructurally, Sertoli cells were seen to form filament-associated junctions in both species. Adjacent Sertoli cells formed microfilament-related junctions near their apices. Filaments of these junctions were arranged in loose networks and were not associated with cisterns of endoplasmic reticulum. In fixed, frozen sections of hagfish testis, similar areas labeled with rhodamine phalloidin, indicating the filament type is actin. In the lamprey, desmosomes were observed immediately below the microfilament-related junctions. In appearance and location, the Sertoli cell junctions observed in these species resembled those of the typical junctional complex of other epithelial cell types. No junctions were observed between Sertoli cells and elongating spermatids. In the hagfish, but not the lamprey, an additional zone of microfilaments occurred near the base of Sertoli cells in areas of association with the basal lamina. Our observations are consistent with the proposal that the unique forms of intercellular attachment found in the testes of higher vertebrates evolved from a typical epithelial form of intercellular junction.     

Variations in the presence of chloride cells in the gills of lampreys (Petromyzontiformes) and their evolutionary implications

Although confined to fresh water, non‐parasitic species of lampreys and the landlocked parasitic sea lamprey, all of which were derived relatively recently from anadromous ancestors, still develop chloride cells, whose function in their ancestors was for osmoregulation in marine waters during the adult parasitic phase. In contrast, such cells are not developed by the non‐parasitic least brook lamprey Lampetra aepyptera, which has been separated from its ancestor for >2 million years, nor by the freshwater parasitic species of the genus Ichthyomyzon. The length of time that a non‐parasitic species or landlocked parasitic form or species has spent in fresh water is thus considered the overriding factor determining whether chloride cells are developed by those lampreys.     

Fungal fimbriae. I. Structure, origin, and synthesis.

Fine hair-like appendages on the cell walls of the another smut Ustilago violacea are described. These hairs are termed fimbriae because of their close similarity to the fimbriae (pili) found on certain Gram-negative bacteria. Cells of U. violacea may carry more than 200 fimbriae varying in length from about 0.5 mum to over 10 mum, and having a diameter of about 60-70 A. Some fimbriae produce knobs similar to those found on bacterial sex fimbriae. Log-phase cells are the most densely fimbriated, while stationary phase cells are devoid of fimbriae. The cells can be defimbriated by sonication, high-speed agitation, or centrifugation through a 40% sucrose solution. The fimbriae can regenerate in these defimbriated cells in about 1 h. This regeneration is inhibited by both cycloheximide and rifampin, but not by chloramphenicol and therefore appears to depend on de novo protein synthesis on cytoplasmic ribosomes. Similar long fimbriae are found on U. maydis and Leucosporidium (Candida) scottii. Short fimbriae, about 0.5 mum long, were found on all the other species of yeast-like fungi examined (Rhodotorula, Saccharomyces, Schizosaccharomyces, Hansenula, Lipomyces, Nadsonia, and Torulopsis spp.).     

Carbohydrates as future anti-adhesion drugs for infectious diseases

Adhesion of pathogenic organisms to host tissues is the prerequisite for the initiation of the majority of infectious diseases. In many systems, it is mediated by lectins present on the surface of the infectious organism that bind to complementary carbohydrates on the surface of the host tissues. Lectin-deficient mutants often lack the ability to initiate infection. The bacterial lectins are typically in the form of elongated submicroscopic multi-subunit protein appendages, known as fimbriae (or pili). The best characterized of these are the mannose-specific type 1 fimbriae, the galabiose-specific P fimbriae and the N-acetylglucosamine-specific fimbriae of Escherichia coli. Soluble carbohydrates recognized by the bacterial surface lectins block the adhesion of the bacteria to animal cells in vitro. Aromatic alpha-mannosides are potent inhibitors of type 1 fimbriated E. coli, being up to 1000 times more active than MealphaMan, with affinities in the nanomolar range. This is due to the presence of a hydrophobic region next to the monosaccharide-binding site of the fimbriae, as recently demonstrated by X-ray studies. Polyvalent saccharides (e.g., neoglycoproteins or dendrimers) are also powerful inhibitors of bacterial adhesion in vitro. Very significantly, lectin-inhibitory saccharides have been shown to protect mice, rabbits, calves and monkeys against experimental infection by lectin-carrying bacteria. Since anti-adhesive agents do not act by killing or arresting the growth of the pathogens, it is very likely that strains resistant to such agents will emerge at a markedly lower rate than of strains that are resistant to antibiotics. Suitable sugars also inhibit the binding to cells of carbohydrate-specific toxins, among them those of Shigella dysenteriae Type 1, and of the homologous Verotoxins of E. coli, specific for galabiose. Appropriately designed polyvalent ligands are up to six orders of magnitude stronger inhibitors of toxin binding in vitro than the monovalent ones, and they protect mice against the Shigella toxin. The above data provide clear proof for the feasibility of anti-adhesion therapy of infectious diseases, although this has not yet been successful in humans. All in all, however, there is little doubt that inhibitors of microbial lectins will in the near future join the arsenal of drugs for therapy of infectious diseases.