THE BIOLOGY OF HARVEYELLA MIRABILIS (CRYPTONEMIALES,RHODOPHYCEAE). VII. STRUCTURE AND PROPOSED FUNCTION OF HOST-PENETRATING CELLS1

The parasitic red alga Harveyella mirabilis (Reinsch) Schmitz & Reinke was examined by light and electron microscopy to determine the structural mechanism involved in nutrient transfer. The host-penetrating rhizoidal cells are unique in possessing an extensive and apparently dynamic endomembrane system as well as other unique cytoplasmic inclusions. The membrane system consists of the plasmalemma, pinocytotic vesicles, multivesicular and concentric bodies, endoplasmic reticulum, dictyosomes, micro-body-like structures and an extensive vacuolar system. It is proposed that this system is active in the uptake and processing of host-derived nutrients. Plasmalemmal extensions (plasmalemmavilli) of Harveyella medullary cells may also function in nutrient uptake.     

A PHYLOGENETIC STUDY OF PARASITIC GENERA PLACED IN THE FAMILY CHOREOCOLACACEAE (RHODOPHYTA)1

Red algal parasites are common and have a unique type of development in which parasite nuclei are transferred to host cells and “control” host cell development. Previous phylogenetic studies have concentrated on parasites closely related to their hosts, termed adelphoparasites. A second set of parasites, usually classified in a different family or tribe from their host, termed alloparasites, have not been studied phylogenetically. This study concentrates on the wholly parasitic family, the Choreocolacaceae (Gigartinales). Using small subunit rDNA sequence data, we found that all the parasites studied are within the same family as their host. Our data support the placement of Holmsella, species of which parasitize Gracilaria and Gracilariopsis, in the order Gracilariales and suggest that Holmsella is an old parasitic genus. Most other species of the Choreocolacaceae parasitize species of the Rhodomelaceae. The one exception is the hyperparasitism between Harveyella mirabilis (Reinsch) F. Schmitz et Reinke (Rhodomelaceae) and the parasite Gonimophyllum skottsbergii Setchell (Delesseriaceae). The parasites Bostrychiocolax australis Zuccarello et West and Dawsoniocolax bostrychiae (Joly et Yamaguishi‐Tomita) Joly et Yamaguishi‐Tomita are placed within the tribe Bostrychiae as are their hosts. Harveyella mirabilis has a single origin and has switched hosts several times during its passage between the Atlantic and Pacific Oceans. Evidence does not support the continued recognition of the family Choreocolacaceae. Our results also indicate that the distinction between adelphoparasites and alloparasites is unwarranted, with a continuum between newly evolved parasites closely related to their hosts and parasites less closely related to their hosts.     

THE BIOLOGY OF HARVEYELLA MIRABILIS (CRYPTONEMIALES; RHODOPHYCEAE). V. HOST RESPONSES FO PARASITE INFECTION1,2

The thallus of Harveyella mirabilis (Reinsch) Schmitz & Reinke is composed of vegetative rhizoidal cells growing intrusively between adjacent cells of the red algal hosts (Odonthalia and Rhodomela) and a protruding reproductive pustule. Although primarily composed of Harveyella cells, host medullary and cortical cells also occur in the emergent pustule. In both tissue regions, Harveyella cells are connected to host cells by secondary pit connections initiated by the host. Direct penetration of host cells by rhizoidal cells of Harveyella occasionally occurs, resulting in host cell death. Degeneration of host medullary cells beneath the pustule may result in a hollow branch and the cortical cells undergo cell division forming a thick palisade layer of randomly associated, photo-synthetically active cells. It is within these branches that the parasite overwinters vegetatively. Host medullary and cortical cells dispersed in the emergent pustule show few of the degenerative responses noted in host cells adjacent to parasite rhizoidal cells. Rather, host cell division, chloroplast division and photosynthetic assimilation of H¹⁴CO^?₃ all increase. Spherical virus-like solitary bodies (S-bodies) occur in all Harveyella cells and in all host cells attached to Harveyella by secondary pit connections. The possibility that these structures may induce the infective response in the host is discussed.     

THE BIOLOGY OF HARVEYELLA MIRABILIS (CRYPTONEMIALES,RHODOPHYCEAE). VI. TRANSLOCATION OF PHOTOASSIMILATED 14C122

Pulse-chase labelling experiments demonstrate that photoassimilated ¹⁴C-bicarbonate is translocated from the host red alga Odonthalia floccosa (Esper) Falkenberg to the parasite Harveyella mirabilis (Reinsch) Schmitz & Reinke. The primary path of translocation is from host cortical cells (the site of photoassimilation) to the erumpent parasite pustule via the zone of interdigitation. The latter is a tissue region in which rhizoidal cells of Harveyella grow between, and establish secondary pit plugs with medullary cells of Odonthalia. A secondary translocation pathway occurs from isolated host cells dispersed in the pustule of Harveyella to adjacent parasite cells.     

Molecular phylogenetics supports a clade of red algal parasites retaining native plastids: taxonomy and terminology revised

Parasitism is a life strategy that has repeatedly evolved within the Florideophyceae. Historically, the terms adelphoparasite and alloparasite have been used to distinguish parasites based on the relative phylogenetic relationship of host and parasite. However, analyses using molecular phylogenetics indicate that nearly all red algal parasites infect within their taxonomic family, and a range of relationships exist between host and parasite. To date, all investigated adelphoparasites have lost their plastid, and instead, incorporate a host‐derived plastid when packaging spores. In contrast, a highly reduced plastid lacking photosynthesis genes was sequenced from the alloparasite Choreocolax polysiphoniae. Here we present the complete Harveyella mirabilis plastid genome, which has also lost genes involved in photosynthesis, and a partial plastid genome from Leachiella pacifica. The H. mirabilis plastid shares more synteny with free‐living red algal plastids than that of C. polysiphoniae. Phylogenetic analysis demonstrates that C. polysiphoniae, H. mirabilis, and L. pacifica form a robustly supported clade of parasites, which retain their own plastid genomes, within the Rhodomelaceae. We therefore transfer all three genera from the exclusively parasitic family, Choreocolacaceae, to the Rhodomelaceae. Additionally, we recommend applying the terms archaeplastic parasites (formerly alloparasites), and neoplastic parasites (formerly adelphoparasites) to distinguish red algal parasites using a biological framework rather than taxonomic affiliation with their hosts.     

The structure and formation of host-parasite pit connections between the red algal alloparasiteHarveyella mirabilis and its red algal hostOdonthalia floccosa

Summary Harveyella mirabilis is a colourless red algal alloparasite which grows on and within its photosynthetic hostOdonthalia floccosa. Cells ofHarveyella establish secondary pit connections (PCs) with other parasite cells and with cells of the host. Small, uninucleate conjunctor cells are produced by parasite cells and remain connected to them by PCs. Conjunctor cells may fuse with either an adjacent host or parasite cell, with the parasite-conjunctor cell PC becoming either a host-parasite or parasite-parasite secondary PC. Occasionally the conjunctor cell does not fuse with an adjacent cell (either host or parasite) and degenerates. The secondary pit plug which forms between a parasite cell and its conjunctor cell always develops with two structurally distinct surfaces characteristic of a host-parasite pit plug. Only if the conjunctor cell fuses with another parasite cell will the structure of the pit plug be altered to that of a parasite-parasite pit plug. Fungal hyphae also invade the region of infection, andHarveyella cells respond by producing nonfunctional conjunctor cells that grow towards adjacent hyphae. Evidence suggests that secondary PCs may be induced to form mechanically, by the physical presence of another cell, rather than in direct response to a message received from an adjacent cell. The mechanism of secondary PC formation described here is similar to that reported for the closely related alloparasiteHolmsella and may be common to a number of red algal parasitic associations. Helen Margaret Quirk, B. Sc. (Hons), M. Sc. (1953–1982), student, research assistant and friend, died after a long illness on October 24, 1982.     

DNA repair in Proteus mirabilis. VI. Plasmid (R46-) mediated recovery and UV mutagenesis.

Summary The expression of plasmid R46-mediated recovery and mutagenic function (s) was studied in P. mirabilis, which is normally either weakly or nonmutable after UV exposure. The plasmid was found to confer on P. mirabilis enhanced UV resistance as well as UV-induced mutability for various types of forward mutations and reversion of the thr273 mutation. The plasmid enhanced survival of UV-irradiated phages in P. mirabilis both in unirradiated host cells and with increased efficiency after UV-exposure of host cells, as is characteristic of UV-inducible phage reactivation. Spontaneous mutability of P. mirabilis harboring R46 was about 2 to 7 times higher than that of cells without plasmid, depending on the marker, repair type, and plating density of the cells used. All of these R46-mediated rescue and mutagenic functions require the rec672⁺ gene function.It is assumed that the plasmid R46 adds functions to P. mirabilis comparable to those deficient in umuC and uvm mutants of E. coli (Kato and Shinoura, 1977; Steinborn, 1978) and that P. mirabilis possesses functions homologous to those controlled in E. coli by the recA ⁺ and lexA ⁺ genes.The significance of plasmid-mediated rescue and mutagenic functions for bacteria which lack the misrepair branch of mutagenesis, is discussed.     

Reconstruction of the musculature of <Emphasis Type="Italic">Magelona</Emphasis> cf. <Emphasis Type="Italic">mirabilis</Emphasis> (Magelonidae) and <Emphasis Type="Italic">Prionospio cirrifera</Emphasis> (Spionidae) (Polychaeta,Annelida) by phalloidin labeling and cLSM

Recent investigations have suggested that a lack of circular muscle fibers may be a common situation rather than a rare exception in polychaetes. As part of a comparative survey of polychaete muscle systems, the F-actin musculature subset of Magelona cf. mirabilis and Prionospio cirrifera were labeled with phalloidin and three-dimensionally analyzed and reconstructed by means of cLSM. Obvious similarities are sublongitudinal lateral, circumbuccal, palp retractor, dominating dorsal longitudinal, perpendicular lateral and ventral transverse muscles. Differences between M. cf. mirabilis and P. cirrifera are: (1) two types of prostomial muscles (transversal and longitudinal) in M. cf. mirabilis versus one type (diagonal) in P. cirrifera; (2) one type of palp muscles (longitudinal) in M. cf. mirabilis versus three types (longitudinal, diagonal, circular) in P. cirrifera; (3) five ventral longitudinal muscles (ventromedian, paramedian, ventral) in M. cf. mirabilis versus four (two paramedian, two ventral) in P. cirrifera. Ventral and lateral transverse fibers are present in the thorax, but absent in the abdomen of M. cf. mirabilis. The triangular lumen of the pharynx in M. cf. mirabilis is surrounded by radial muscle fibers; three sets of pharynx diductors attach to its dorsal side. The unique features of P. cirrifera are one pair of brain muscles and segmentally arranged dorsal transverse muscles, the latter located outside the longitudinal muscles. The transverse lateral muscles are restricted to the sides and lie beneath the longitudinal muscles, a pattern described here for the first time. A true, outer layer of circular fibers is absent in both species of Spionida that were investigated.     

Helicosporidium infection of the great European spruce bark beetle, Dendroctonus micans (Coleoptera: Scolytidae)

An infection of the great European spruce bark beetle Dendroctonus micans (from Turkey) by the parasitic green alga Helicosporidium is described. This is the first time that Helicosporidium has been found to infect a bark beetle (Scolytidae) and the first time that a naturally infected beetle has been reported for the Eurasian continent. The typical cysts of Helicosporidium contain three ovoid cells and one helical, filamentous cell. The morphological characteristics are revealed by light and electron microscopy. Distinct electron-dense inclusions with a peculiar ultrastructure may represent pyrenoids. Since D. micans is an important pest, the discovery of a natural pathogen may offer a chance for biological control.     

Heterochrony and the evolution of the longjaw mudsucker (Gobiidae,Teleostei)

Although longjaw mudsucker (Gillichthys mirabilis, Gobiidae) has been studied extensively for its ability to occupy low-oxygen environments, few studies have addressed the evolution of its exceptionally elongated jaws that extend posteriorly beyond the gill opening in large adults. In this study, the ontogeny of the maxillae of G. mirabilis, Gillichthys seta, and the out-group species Eucyclogobius newberryi was studied within the heterochrony framework using digitized landmarks and caliper measurements. The results show that the maxilla of both species of Gillichthys evolved via acceleration (increased growth rate) and that of G. mirabilis via hypermorphosis (continued growth to a larger body size); two forms of peramorphosis. This is in contrast to earlier studies that concluded that G. seta is paedomorphic. We were unable to confirm an earlier hypothesis of sexual dimorphism in the jaw length of G. mirabilis. The evolution of the elongated jaws and associated large buccopharyngeal membrane in G. mirabilis is hypothesized to increase the surface area for gas exchange during aerial respiration and may also serve to amplify the aggressive gaping display as observed in other fishes.     

Phase contrast X‐ray synchrotron microtomography and the oldest damselflies in amber (Odonata: Zygoptera: Hemiphlebiidae)

Electrohemiphlebia barucheli gen. et sp. nov. and Jordanhemiphlebia electronica gen. et sp. nov. , two new genera and species are described, based on exceptional inclusions of hemiphlebiid damselflies in Cretaceous amber from France and Jordan. The type specimen of E. barucheli was studied using phase contrast X‐ray synchrotron microtomography, giving exceptional images and detailed information. Its comparison with the recent Hemiphlebia mirabilis confirms the attribution of several Cretaceous damselflies to the Hemiphlebiidae, showing that this particular group was widespread in the Early Cretaceous and probably originated in the Late Jurassic or earlier. The ecological niches today occupied by the small coenagrionoid damselflies were occupied during the Triassic and Jurassic by Protozygoptera, hemiphlebiids during the Early Cretaceous, and modern taxa in the Cenozoic.     

A DESCRIPTION OF HAPLOZOON AXIOTHELLAE N. SP., AN ENDOSYMBIONT OF THE POLYCHAETE AXIOTHELLA RUBROCINCTA12

A new parasitic dinoflagellate, Haplozoon axiothellae sp. nov., is described from the intestine of the marine polychaete Axiothella rubrocincta. The parasites are 40–175 μm long with 2–26 cells arranged in single or double rows. Two cytoplasmic inclusions previously unknown in this genus are described. The first is globular and varies in size, while the second is approximately 2 μm long and peanut-shaped. The function and composition of the inclusions are unknown. Nuclear structure and karyokinesis are apparently different from those of typical dinoflagellates.     

Ultrastructure of presumptive light sensitive ciliary organs in larvae of Poecilochaetidae,Trochochaetidae, Spionidae,Magelonidae (Annelida) and its phylogenetic significance

Larvae of Poecilochaetus serpens, Trochochaeta multisetosum and Polydora ciliata possess almost identical unpigmented, ciliary, presumptive light sensitive organs within the prostomium. The data corroborate hypotheses on the close relationship of Poecilochaetidae, Trochochaetidae and Spionidae and are even congruent with inclusion of Poecilochaetidae and Trochochaetidae within Spionidae. The organs in P. serpens, T. multisetosum and P. ciliata are composed of one monociliary receptor cell, one supportive cell and several associated flask shaped bipolar sensory cells. The receptor cell cilium enters the supportive cell cavity through a thin pore, dilates and then branches into a high number of disordered projections. The associated sensory cells bear one or occasionally two cilia, which run horizontally beneath or within the cuticle. The supportive cell cavity is not sealed by any cell contact from the subcuticular extracellular space. The organs in Magelona mirabilis are composed of a single supportive cell, but several receptor cells. No further sensory cells are associated. Each receptor cell sends one cilium into an own invagination of the supportive cell, and the ciliary branches are highly ordered. The examined organs in P. serpens, T. multisetosum and P. ciliata exhibit a unique organization amongst polychaetes. The organs of M. mirabilis are most probably homologous. A homology to ciliary organs of Protodrilida is conceivable. In the lineage leading to Protodrilida, primary larval organs may have been integrated into the adult body organization by heterochrony.     

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.     

Unveiling a Ghost of Amazonian Rain Forests: Camponotus mirabilis,Engineer of Guadua Bamboo1

Camponotus mirabilis (Hymenoptera: Formicidae) is a highly specialized resident of live Guadua bamboo in western Amazonia. Workers in established colonies open and invade young, unlignified culms, and mature polydomous colonies occupy several‐to‐many adjacent stems. Multistoried carton shelves support brood inside culms, and larvae are nourished by honeydew of coccids (Cryptostigma guadua). Constructing a system of stem holes and wicks, C. mirabilis modifies occupied stems in ways that produce passive water evacuation. Nocturnally foraging workers gather both prey and wood fiber, a component of wicks. Diurnally, they boil aggressively from agitated stems, and are attacked by parasitic phorid flies (Diptera: Phoridae). Culms housing C. mirabilis are stouter and more erect than are unoccupied stems but are opened regularly by capuchin monkeys (Cebus apella) searching for brood and perhaps reproductive castes. Damaged by monkeys, weak‐walled Guadua stems frequently collapse and are abandoned by ants. Breakdown of brood shelves leaves nutrient‐rich carton suspended in water within basal internodes, but isotopic analyses fail to show that occupied culms utilize either nitrogen from carton or carbon respired by ants or decomposing debris. Lower foliar nitrogen concentration in occupied than in control stems suggests that coccids and ants parasitize host resources. A prior experimental survey of bamboo ants may have missed C. mirabilis because females found new colonies in culms occupied by another bamboo specialist, and established colonies invade only young bamboo growth.     

Morpho-anatomical features of the leaves of the mediterranean geophyteUrginea maritima (L) baker (Liliaceae)

The morpho-anatomy and histochemistry of the hysteranthous leaf ofUrginea maritima (L.) Baker and its adaptive strategies to the Mediterranean climate were investigated. The leaf ofU. maritima is 714 μm thick and possesses moderate specific leaf mass (8.564 mg cm^-2) and low tissue density (136.5 mg cm^-3). The epidermal cells are compactly arranged and covered with cuticle. The average density of stomata in lower epidermis is higher than that of the upper one. The mesophyll cells occupy 52.96% of the total volume of the leaf, while the mesophyll intercellular spaces and the air spaces occupy 30.41%. Idioblastic cells containing raphide bundles and different phenotypes of crystalloid inclusions, embedded in polysaccharides, occur in the lower side of the mesophyll. The presence of oil droplets and lipids is evident. Bundle sheath cells are hardly visible with no chloroplasts which are a pronounced C₃ plant character. Plastids containing protein crystalloid inclusions are abundant in the protophloem sieve elements.U. maritima, a deciduous plant, possesses leaves with mesophytic characters, in order to optimize its adaptation to the seasonal fluctuation of environmental conditions of the Mediterranean climate.     

Ultrastructure of crystalline inclusions in the thylakoids of dodder<Emphasis Type="Italic">(cuscuta japonica)</Emphasis> plastids

The plastids from seedlings of the parasitic angiospermCuscuta japonica were ultrastructurally investigated. In shoot subapical cells from 3-d-old seedlings grown in the dark, the etioplasts contained prolamellar bodies and amorphous and dense inclusions. In the shoot subapical cells obtained from 6-d-old seedlings grown under light conditions for the last 3 d, the underdeveloped chloroplasts contained phytoferritin within the stroma as well as amorphous and dense inclusions that were limited by the thylakoid membranes. In the developing chloroplasts, electron-dense materials were detected within the transversely sectioned thylakoid lumens. This dense material presented two different images, depending upon the sectional plane. When transversely prepared, the materials appeared as somewhat thick, linear structures, whereas longitudinally sectioned thylakoids revealed very large crystalline inclusions. In the developed chloroplasts, the amounts of electron-dense material or crystalline inclusions were remarkably reduced in the thylakoid lumens, which were electron-translucent. Far fewer crystalline inclusions were observed in the developed chloroplasts of seedlings than in the developing chloroplasts. These results suggest that the crystalline inclusions may be temporarily reserved within the thylakoid lumens of chloroplasts in the Gjaponica seedlings.     

Revision of the genera Nemotha Wood-Mason, 1884 and Tricondylomimus Chopard, 1930 stat. rev., with description of a new species (Dictyoptera: Mantodea)

The oriental species previously included in the rarely collected genus Nemotha Wood-Mason, 1884 (Mantodea: Iridopterygidae) are revised. N. coomani (Chopard, 1930) and N. mirabilis Beier, 1933 strongly differ from the type species N. metallica (Westwood, 1845) by family-level morphological features, but share a unique type of forefemoral armament with the genera Hapalopeza Stål, 1877 and Amantis Giglio-Tos, 1915, suggesting Nemotha is of a polyphyletic nature. The genus Tricondylomimus Chopard, 1930 is resurrected from synonymy to accommodate T. coomani, T. mirabilis n. comb. and the species which is newly described in this article, T. intermedius n. sp. The monotypic genus Pseudogousa Tinkham, 1937 and its species P. sinensis Tinkham, 1937 are synonymized with Tricondylomimus and T. mirabilis, respectively. The genus Tricondylomimus is placed in Iridopterygidae, while Nemotha is transferred to Hymenopodidae: Anaxarchini.     

The Serratia marcescens hemolysin is secreted but not activated by stable protoplast-type L-forms of Proteus mirabilis

The outer-membrane protein ShlB of Serratia marcescens activates and secretes hemolytic ShlA into the culture medium. Without ShlB, inactive ShlA (termed ShlA*) remains in the periplasm. Since Proteus mirabilis L-form cells lack an outer membrane and a periplasm, it was of interest to determine in which compartment recombinant ShlA* and ShlB are localized and whether ShlB activates ShlA*. The cloned shlB and shlA genes were transcribed in P. mirabilis stable L-form cells by the temperature-inducible phage T7 RNA polymerase. Radiolabeling, Western blotting, and complementation with C-terminally truncated ShlA (ShlA255) identified inactive ShlA* in the culture supernatant. ShlB remained cell-bound and did not activate ShlA without integration in an outer membrane. Although hemolytic ShlA added to L-form cells had access to the cytoplasmic membrane, it did not affect L-form cells. Synthesis of the large ShlA protein (165 kDa) in P. mirabilis L-form cells under phage T7 promoter control demonstrates that L-form cells are suitable for the synthesis and secretion of large recombinant proteins. This property and the easy isolation of released proteins make L-form cells suitable for the biotechnological production of proteins. Received: 17 February 1998 / Accepted: 30 June 1998     

A new southern distribution limit for Sorex mirabilis Ognev, 1937 (Eulipotyphla,Soricidae)

Sorex mirabilis, a small insectivorous mammal, is a very rare, poorly known species distributed at high latitudes and altitudes of northeastern Asia. The occurrence of this species in the Republic of Korea was known from late 1990s. We found a new specimen from a location of a 50′ lower latitude and 400 m lower altitude than the previously known locations of the first record in the Republic of Korea. This finding may imply that S. mirabilis is distributed in a wider range than previously considered and that their distribution might be related to eoreumgols, or ice valleys, where there are potential insular refugia due to micro-meteorological characteristics.