Ultrastructure of the body cavities in Phylactolaemata (Bryozoa)

Only species belonging to the bryozoan subtaxon Phylactolaemata possess an epistome. To test whether there is a specific coelomic cavity inside the epistome, Fredericella sultana, Plumatella emarginata, and Lophopus crystallinus were studied on the ultrastructural level. In F. sultana and P. emarginata, the epistome contains a coelomic cavity. The cavity is confluent with the trunk coelom and lined by peritoneal and myoepithelial cells. The lophophore coelom extends into the tentacles and is connected to the trunk coelom by two weakly ciliated coelomic ducts on either side of the rectum. The lophophore coelom passes the epistome coelom on its anterior side. This region has traditionally been called the forked canal and hypothesized to represent the site of excretion. L. crystallinus lacks an epistome. It has a simple ciliated field where an epistome is situated in the other species. Underneath this field, the forked canal is situated. Compared with the other species, it is pronounced and exhibits a dense ciliation. Despite the occurrence of podocytes, which are prerequisites for a selected fluid transfer, there is no indication for an excretory function of the forked canal, especially as no excretory porus was found. J. Morphol. 2009. © 2008 Wiley‐Liss, Inc.     

Transmission of Tetracapsuloides bryosalmonae (Myxozoa: Malacosporea) to Fredericella sultana (Bryozoa: Phylactolaemata) by various fish species

Tetracapsuloides bryosalmonae is a myxozoan parasite of salmonids and freshwater bryozoans, which causes proliferative kidney disease (PKD) in the fish host. To test which fish species are able to transmit T. bryosalmonae to bryozoans, an infection experiment was conducted with 5 PKD-sensitive fish species from different genera. Rainbow trout Oncorhynchus mykiss, brown trout Salmo trutta, brook trout Salvelinus fontinalis, grayling Thymallus thymallus and northern pike Esox lucius were cohabitated with T. bryosalmonae-infected Fredericella sultana colonies and then subsequently cohabitated with statoblast-reared parasite free Bryozoa. Statoblasts from infected colonies were tested by PCR to detect cryptic stages of T. bryosalmonae, which may indicate vertical transmission of the parasite. In this study, brown trout and brook trout were able to infect Bryozoa, while there was no evidence that rainbow trout and grayling were able to do so. Few interstitial kidney stages of the parasite were detected by immunohistochemistry in brown trout and brook trout, while rainbow trout and grayling showed marked proliferation of renal interstitial tissue and macrophages with numerous parasite cells. Intraluminal stages in the kidney tubules were only detected in brown trout and rainbow trout. In contrast to previous observations, pike was not susceptible to PKD in these trials according to the results of T. bryosalmonae-specific PCR. No DNA of T. bryosalmonae was detected in any statoblast.     

Freshwater bryozoans (Bryozoa: Phylactolaemata) as vectors of salmonid disease

Relations of PKX [vector of proliferative kidney disease (PKD)] of reared and wild Salmonoidea and Tetraspora bryozoides, the only genus and species of Myxozoa found in fresh water Bryozoa, is discussed using recent publications. Both organisms were found in several European countries as well as in North America. It seems that PKX is a Bryozoa parasite which do not undergo full cycle of sporulation in fish.     

Ultrastructural study of metamorphosis in the freshwater bryozoan Plumatella fungosa (Bryozoa,Phylactolaemata)

Summary

At metamorphosis the attachment of the Plumatella larva to the substrate is effected by secretions from glandular cells in the apical plate, the leading pole during swimming. The larval mantle folds back and slides down towards the substrate. By ciliary activity an adhesive secretion is spread over the metamorphosing larva and the attachment area. Two polypides appear through the larval terminal opening. The mantle fold, together with gland cells, nerve cells, sensory cells, and muscle cells from the larva form a nutritive cell mass. Reduction of this nutritive cell mass is accomplished by autolysis and phagocytosis. An invaginated area of the nutritive cell mass is provided with a dense layer of microvilli, which seem to have an absorbtive function. The nutritive cell mass consisting of transitory larval tissues provides a significant source of nutrient for the developing polypide buds.     

Biochemical genetics and taxonomy in Plumatella emarginata and P. repens (Bryozoa: Phylactolaemata)

SUMMARY. Although morphological distinctions are well documented, many authors have regarded the freshwater bryozoan Plumatella emarginata as a variety of P. repens. Differences between the two nominate species have been studied by the electrophoretic examination of genetic variation at enzyme loci. Genetic identity (Nei, 1972) was 0.286, a value well below that expected for conspecific allopatric populations. The results leave little doubt that specimens of the two species are from quite distinct and separate gene pools, with an unexpectedly high level of genetic differentiation. It is therefore concluded that P. emarginata is a valid species and is not merely a variety of P. repens. Morphological differences between the two species are also discussed.     

Biochemical genetics and taxonomy in Plumatella fungosa and P. repens (Bryozoa: Phylactolaemata)

SUMMARY. Some authors have recently concluded that, using morphological criteria, the freshwater bryozoans Plumatella repens and P. fugosa cannot be separated and should be regarded as conspecific. To test this conclusion, electrophoretic techniques have been used to examine genetic differences between the two nominate species at several enzyme loci. Significant variation at a malate dehydrogenase locus and three aminopeptidase loci establish beyond doubt that P. repens and P. fugosa are separate but related species. No significant variation was found between two populations of P. repens . Morphological characters for the distinction of the two species are discussed and evaluated.     

Sequential development of Buddenbrockia plumatellae (Myxozoa: Malacosporea) within Plumatella repens (Bryozoa: Phylactolaemata)

Colonies of the freshwater bryozoan Plumatella repens collected from a river in the UK were found to be infected with the myxozoan parasite Buddenbrockia plumatellae following laboratory maintenance. Optimisation of the bryozoan diet allowed maintenance of infected colonies for 90 d, permitting observation by light and electron microscopy of the sequential parasitic developmental cycle. Parasite stages were associated with host peritoneum, identifying the primary developmental phase. The association of B. plumatellae cells with peritoneal basal lamina and morphological similarities between parasite and host suggested that the parasite remodelled host tissue. Progressive expansion and elongation of individual parasites led to the release of freely floating vermiform stages within the host coelomic cavities. Within these 'worms', intraluminal masses developed, resulting in the formation of spores. Upon maturation, the 'worms' ruptured, releasing many spores within the host that were subsequently discharged. Although parasitism led to increased bryozoan fragmentation and lowered statoblast production, some colonies did survive, resulting in repeated waves of infection. Long-term laboratory maintenance of infected bryozoan colonies could provide a means of maintaining B. plumatellae for study until the full life cycle is ascertained.     

Proliferative, presaccular stages of Tetracapsuloides bryosalmonae (Myxozoa: Malacosporea) within the invertebrate host Fredericella sultana (Bryozoa: Phylactolaemata)

Proliferative kidney disease (PKD), caused by the malacosporean parasite, Tetracapsuloides bryosalmonae, is a major disease of salmonid culture both in western Europe and North America. The fish are infected from spores that develop within freshwater bryozoans and are released into the water column. Although sporogenesis has been studied in the bryozoan host and occurs within sacs, the formation of these sacs from presaccular stages has only been hypothesized. Examination of infected bryozoans by using a range of techniques identified proliferating, presaccular amoeboid stages of T. bryosalmonae on the body wall of the bryozoan Fredericella sultana. These stages possessed unique electron-dense bodies and were observed as aggregating within the bryozoan metacoel, differentiating to form spore sacs. Spore sac growth was associated with the assimilation of the presaccular parasites rather than through cryptomitosis of sac mural cells. This sac formation through aggregation and assimilation suggests an intriguing mechanism by which T. bryosalmonae can cross-fertilize.     

Molecular markers to discriminate among four pest species of Helicoverpa (Lepidoptera: Noctuidae)

The four significant pest species in the Helicoverpa genus (H. armigera, H. assulta, H. punctigera and H. zea) are morphologically similar and can only be reliably distinguished through dissection of adult genitalia. Two partial regions of the mitochondrial DNA (mtDNA), the cytochrome oxidase subunit I (COI) and the cytochrome b (Cyt b) genes were amplified by PCR and digested with restriction endonucleases. The restriction patterns, generated by the endonucleases BstZ17I and HphI, demonstrated reliable differentiation of the four Helicoverpa pest species. This technique is fast, reliable and effective at distinguishing specimens irrespective of their life stages and offers support to conventional taxonomic differentiation based on morphological characters.     

Some Antarctic and sub-Antarctic species of Celleporidae (Bryozoa, Cheilostomata)

Sixteen species of cheilostome Bryozoa, within the family Celleporidae Busk, 1852, are reported from Antarctica and the sub-Antarctic south-west Atlantic. Nine new species are described in the genera Osthimosia Jullien, 1888, Celleporina Gray, 1848 and Turbicellepora Ryland, 1963. Spigaleos gen. nov. is introduced for Cellepora horneroides Waters, 1904.     

Ultrastructure of Buddenbrockia allmani n. sp. (Myxozoa, Malacosporea), a parasite of Lophopus crystallinus (Bryozoa, Phylactolaemata)

Development of a new species of malacosporean myxozoan (Buddenbrockia allmani n. sp.) in the bryozoan Lophopus crystallinus is described. Early stages, represented by isolated cells or small groups, were observed in the host's body wall or body cavity. Multiplication and rearrangement of cells gave an outer cell layer around a central mass. The outer cells made contact by filopodia and established adherens junctions. Sporoplasmosomes were a notable feature of early stages, but these were lost in subsequent development. Typical malacosporean sacs were formed from these groups by attachment of the inner (luminal) cells by a basal lamina to the outer layer (mural cells). Division of luminal cells gave rise to a population of cells that was liberated into the lumen of the sac. Mitotic spindles in open mitosis and prophase stages of meiosis were observed in luminal cells. Centrioles were absent. Detached luminal cells assembled to form spores with four polar capsules and several valve cells surrounding two sporoplasms with secondary cells. Restoration of sporoplasmosomes occurred in primary sporoplasms. A second type of sac was observed with highly irregular mural cells and stellate luminal cells. A radially striated layer and dense granules in the polar capsule wall, and previous data on 18 rDNA sequences enabled assignment of the species to the genus Buddenbrockia, while specific diagnosis relied on the rDNA data and on sac shape and size.     

Redox potential to discriminate among species of lactic acid bacteria

AIMS: To verify to what degree reducing capacity is a characterizing parameter of a species, and of the strains themselves within a given species, of lactic acid bacteria. METHODS AND RESULTS: Eighty-eight strains belonging to 10 species of lactic acid bacteria (LAB) isolated from traditional Italian cheeses were studied for their reduction activity: Enterococcus faecalis, Enterococcus faecium, Enterococcus durans, Streptococcus thermophilus, Lactococcus lactis ssp. lactis, Lactobacillus paracasei ssp. paracasei, Lactobacillus plantarum, Lactobacillus delbrueckii ssp. bulgaricus, Lactobacillus helveticus and Pediococcus pentosaceus. It was observed that the lactococci reached minimum redox potential before the lactobacilli. The reduction rate of Enterococcus spp. and L. lactis ssp. lactis was higher than that of the streptococci and Lactobacillus spp. All the P. pentosaceus strains had poor reduction activity compared with the other species. CONCLUSIONS: The evolution of the redox potential in milk over a time span of 24 h has been found to be a parameter that characterizes a species: the different courses corresponding to the species in question are clearly evident, and interesting differences can also be noted within the same species. SIGNIFICANCE AND IMPACT OF THE STUDY: The reduction aptitude of strains might be used to select and adapt appropriate strains for use as starters for dairy products.     

Some British species of Schizomavella (Bryozoa: Cheilostomatida)

Six British species of the Cheilostomatous bryozoan genus Schizomavella Canu & Bassler, 1917 are described and figured. Neotype specimens are selected for S. auriculata (Hassall) and S. linearis (Hassall), and lectotypes are selected for S. cuspidata (Hincks) and 5. hastata (Hincks). S. hastiformis Hayward and Ryland is placed in synonymy with S. linearis. S. sarniensis sp. nov. is described from several south-west British localities.     

The British species of Schizoporella (Bryozoa: Cheilostomatida)

Three new species are described in the cheilostomate bryozoan genus Schizoporella Hincks, 1877. British records of Scliizoporella dunkeri Reuss are shown to represent two previously unnamed species. Scliizoporella dunkeri is the senior synonym of the Adriatic species Schizoporella longirostris Hincks. Material of S. longirostris from British localities is referred in part to S. dunkeri and in part to a previously unnamed species.     

Identification and genetic relationships among nine Albizzia species based on morphological and molecular markers

Abstract

Identifying germplasm is an important component for efficient and effective management of plant genetic resources. This investigation was undertaken for the identification and analysis of genetic variation within 9 species of Albizzia through 33 morphological parameters, and 15 Random Amplified Polymorphic DNA (RAPD) and 17 Inter Simple Sequence Repeat (ISSR) primers. The use of selected RAPD and ISSR primers generated a total of 163 and 201 amplified DNA fragments, respectively. High frequencies of polymorphism, 95.05% for RAPD and 96.02% for ISSR, were detected. Statistical approaches were employed to construct genetic relationships by RAPD, ISSR and morphological analysis. Cluster analysis by the unweighted pair-group method (UPGMA) of Nei's similarity generated dendograms with similar topology that gave a better reflection of the diversity and affinities between species. These molecular results were comparable to main morphological characteristics. The correlation matrices generated by RAPD and ISSR markers were highly correlated (r = 0.843 at p = 1.0), thereby indicating congruence between these two marker systems. Both morphometric data and molecular markers have the potential to analyse genetic variation among the nine species of Albizzia, thus providing a major input for management strategy of plant genetic resources.     

Some Antarctic and sub-Antarctic species of Smittinidae (Bryozoa: Cheilostomata)

Twenty-six species of Bryozoa, in the ascophoran cheilostome family Smittinidae Levinsen, 1909, are described from Antarctic and sub-Antarctic localities. Fourteen species are considered to be new to science. Aspericreta gen. nov. is introduced for Smittina crassatina Waters, 1904, and Platychelyna gen. nov. for Cellarinella planulata Hayward, 1980.     

Assessment of the genetic distances between some species of the family Bradybaenidae (Mollusca,Pulmonata)

On the basis of inter-simple sequence repeat (ISSR) loci and the nucleotide sequences of nuclear (18S and ITS-1) and mitochondrial genes (COI and 16S), a phylogenetic analysis of the three species of terrestrial mollusks of the family Bradybaenidae (Mollusca, Pulmonata), Bradybaena fruticum Müll., Bradybaena schrencki Midd., and Bradybaena transbaicalia Shileyko, was conducted to clarify their taxonomic status. The analysis showed that Br. fruticum was far apart from the other two species (Br. schrencki and Br. transbaicalia). The genetic distance between the latter puts in doubt their status as distinct species. It is suggested that the species Br. transbaicalia can be treated as a form of Br. schrencki var. transbaicalia.