Chloride cells and chloride exchange in the skin of a sea-water teleost,the shanny (Blennius pholis L.)

Summary The fine structure of the skin and its importance in chloride outfluxes were investigated in a sea-water teleost, the shanny (Blennius pholis L.).The epidermis is composed of three cells types: epithelial cells, mucous cells and chloride cells. These chloride cells typically contain a great number of mitochondria and an extensive agranular reticulum extending through the whole cell body. They open at the surface of the epidermis into an apical pit. An undifferentiated small cell is often observed near these chloride cells and probably corresponds to the adjacent chloride cell.The values of chloride outfluxes through the skin and the gills are respectively 5333±884 Eq·h^–1·kg^–1 and 4479±2521 Eq·h^–1·kg ^–1; n=6; t=13±0.5°C. Thus the ratio between skin chloride outflux and total chloride outflux is 64.7±9.3%.     

Diet of Lipophrys pholis (L.) (Teleostei,Blenniidae) in Cantabrian coastal waters (Spain)

Between February and December 1988, a total of 261 specimens of Lipophrys pholis were caught in eleven intertidal pools on the western coast of Asturias. This blenniid species mainly feeds on different groups of invertebrates, although algal remains also appear. Mollusca is the most highly represented taxon with the largest number of prey being Gastropoda, followed by Bivalvia and, to a lesser degree, Polyplacophora. Crustacea is well represented by Cirripedia. Isopoda also stands out and Amphipoda, Tanaidacea and Decapoda appear sporadically. Temporal diet analysis throughout the year shows no great differences. Likewise, a great similarity was observed among the feeding of L. pholis specimens collected in pools at a different tidal level, of variable size and with different algal cover. Changes in diet are appreciable as size increases, especially from a length of 6 cm on.     

Use of cues by Lipophrys pholis L. (Teleostei, Blenniidae) in learning the position of a refuge

The ability of Lipophrys pholis to remember the position of a refuge was tested in an artificial habitat under the influence of different visual clues. L. pholis learned the position of the refuge in the presence of a clue consisting only of a small black screen. They responded to this clue by moving towards it and pressing themselves up against it. Lego towers and a white screen clue did not provoke such a response. In a further experiment L. pholis continued to respond to the black screen in this way when the screen was moved to another location further from the refuge. After 12 days L. pholis learned to use the black screen in its new position as an indirect clue and navigate to the refuge directly without first approaching the black screen. These results suggested that when placed in a novel habitat the immediate reaction of L. pholis is to move quickly towards the first dark area they see but, with experience, they can use the position of large objects around them to navigate quickly and efficiently to a refuge.     

The morphology of the club glands on the dorsal fin of mature male shannies, Lipophvys pholis (L.) (Blenniidae: Teleostei)

The pelvic, pectoral, anal and dorsal fins of mature male, female and immature male Lipophrys pholis (L.) were examined by light microscopy for the presence of club glands. All fins except the dorsal showed a highly stratified epidermis and a thick cuticle. Club glands were present on the dorsal fin of mature male fisH but only during the breeding season. The development and decline of the club glands corresponds to the period of gonadal build-up and spawnout. Each club gland comprises several thousand bundles ofcolumnar cells. The columnar cells surround acentral pore which opens to the outside through a layer of Malpighian cells. The substance produced by the gland includes mucopolysacchdride. The function of the secretion is unknown and is discussed in relation to studies on similar glands in several Mediterranean blenniids.     

Functions of the testicular gland in two blenniid fishes, Salaria (=Blennius) pavo and Lipophrys (= Blennius) dalmatinus (Blenniidae, Teleostei) as revealed by electron microscopy and enzyme histochemistry

The functions of the testicular gland in two different blenniid fishes, Salaria pavo and Lipophrys dulmutinus , are described by fine structural and enzyme histochemical methods. In the testes of the two fishes no mature spermatozoa are found. Sperrniogenesis occurs only until the spermatidal stage. Spermatids are released into the testicular gland. During the spawning period the testicular gland functions in differentiation of spermatids, nutrition of spermatids, and secretion of sialomucins. After spawning, the testicular gland has phagocytotic functions in resorbtion of remaining spermatids, which are transformed into lipids in the gland cells. During the interspawning period the testicular gland is a storage reservoir for lipids and phospholipids which are re-transformed into testicular gland secretion in the next reproductive season. Testicular gland cells themselves do not have steroidogenetic functions, but steroids are synthesized by interstitial cells homologous to Leydig cells in other fish. Possible explanations for the reduction of the testis in L. dalmatinus and implications of the testicular gland in taking over testicular functions are discussed.     

Host–parasite interactions and vectors in the barn swallow in relation to climate change

Recent climate change has affected the phenology of numerous species, and such differential changes may affect host–parasite interactions. Using information on vectors (louseflies, mosquitoes, blackflies) and parasites (tropical fowl mite Ornithonyssus bursa, the lousefly Ornithomyia avicularia, a chewing louse Brueelia sp., two species of feather mites Trouessartia crucifera and Trouessartia appendiculata, and two species of blood parasites Leucozytozoon whitworthi and Haemoproteus prognei) of the barn swallow Hirundo rustica collected during 1971–2008, I analyzed temporal changes in emergence and abundance, relationships with climatic conditions, and changes in the fitness impact of parasites on their hosts. Temperature and rainfall during the summer breeding season of the host increased during the study. The intensity of infestation by mites decreased, but increased for the lousefly during 1982–2008. The prevalence of two species of blood parasites increased during 1988–2008. The timing of first mass emergence of mosquitoes and blackflies advanced. These temporal changes in phenology and abundance of parasites and vectors could be linked to changes in temperature, but less so to changes in precipitation. Parasites had fitness consequences for hosts because intensity of the mite and the chewing louse was significantly associated with delayed breeding of the host, while a greater abundance of feather mites was associated with earlier breeding. Reproductive success of the host decreased with increasing abundance of the chewing louse. The temporal decrease in mite abundance was associated with advanced breeding of the host, while the increase in abundance of the lousefly was associated with earlier breeding. Virulence by the tropical fowl mite decreased with increasing temperature, independent of confounding factors. These findings suggest that climate change affects parasite species differently, hence altering the composition of the parasite community, and that climate change causes changes in the virulence of parasites. Because the changing phenology of different species of parasites had both positive and negative effects on their hosts, and because the abundance of some parasites increased, while that of other decreased, there was no consistent temporal change in host fitness during 1971–2008.     

Phylogenetic interpretations and ecological potentials of the Mesomycetozoea (Ichthyosporea)

The Mesomycetozoea (Ichthyosporea) includes a group of fungus-like microorganisms which diverged near the animal fungus divide and is basal to the animal lineage in the Opisthokont supergroup. The composition of species within this group has changed considerably since it was reviewed by Mendoza et al. in 2002. There have been many additions to the group as a result of phylogenetic sequencing, and new species have been discovered following examination of digestive tracts of arthropods and other groups of invertebrates. Furthermore, ecological surveys and environmental sampling have revealed a high diversity of Mesomycetozoean phylotypes in marine, freshwater and terrestrial environments. Initially considered a group comprising mainly fish parasites, the Mesomycetozoea are now known to live in association with a wide range of host organisms including invertebrates, fish, amphibians, birds and mammals. Here we review the Mesomycetozoea and examine the broad spectrum of its ecology in the light of recent research based on sequence data, cultivation and in vivo studies.     

Tyrrhenia blennii g.n. sp. n. (Hemiurata : Halipegidae Poche, 1925) parasite of Blennius gattorugine and Blennius sanguinolentus]

Trematodes recovered from Blennius gattorugine and Blennius sanguinolentus from the Gulf of Gaeta, Italy, are described and figured as Tyrrhenia blennii g.n. sp.n. The new genus differs from other members of the Arnolinae Skrjabin and Guschanskaja, 1958 (Halipegidae Poche, 1925) chiefly in having acetabulum equatorial, receptaculum seminis uterinum present and eggs without filaments. The diagnosis of the new genus Tyrrhenia and a key to genera of Arnolinae are given.     

Histochemical studies of acid proteoglycans and glycoproteins and activities of hydrolytic and oxidoreductive enzymes in the skin epidermis of the fish Blennius sanguinolentus pallas (Teleostei: Blenniidae)

In the epidermis of the fish Blennius sanguinolentus the histochemistry of complex carbohydrates and various oxidoreductases has been studied by means of a series of selected light microscopical techniques. The epidermis is endowed with three types of secretory cells namely, the mucous goblet cells, the superficial polygonal cells and the ionocytes, which provide protective functions in view of their involvement in the prevention of the skin epithelium from invading pathogens and in the osmoregulation processes respectively. The secretory substances of mucous goblet cells contain sulfated, carboxylated and neutral complex carbohydrates in addition to a glycoprotein with sialic acid terminal to galactose in its oligosaccharide chains. Activities of SDH, ICDH, MDH and G-6-PDH were studied, to elucidate some aspects of the correlated functions of the ionocytes which play a key role in the performance of the maintenance of the electrolyte pattern in the internal milieu of the skin. Differences in the intensity of various oxidoreductases are correlated with the extent of the activity of the epidermis for related to secretion of a mucous cover over the surface. Activity of the oxidoreductases is confined mainly to the basal and outer epidermal layers and this enzyme zonation is discussed with reference to the existence of the high turnover rate of the epithelial cells and both the proliferative and respiratory capabilities of the skin epithelium.     

Morphological evidence for the biological role of caniniform teeth in combtooth blennies (Blenniidae, Teleostei)

Combtooth blennies have recurved, fang-like caniniform teeth at the rear end of a single row of incisiform teeth. The lengths and positions of these canines were measured in the lower jaws of males of 14 species of Mediterranean Blenniidae. In four species, lower jaw canines were measured in males and females, while in one species, the upper jaw canines of both sexes were also measured. Relative (to body length) canine length in males tends to be significantly greater (10–40%) than in females. There are significant interspecific differences in relative canine length, with smaller species tending to have relatively larger teeth. No significant correlation was obtained between canine length and importance of animal prey in the diet, nor with 'hole fit' of males, which may be related with the intensity of paternal care. We suggest that canines in combtooth blennies are predominately used for predator deterrence and agonistic interactions.     

Juvenile recruitment, growth and maturation of Lipophrys pholis (Pisces: Blenniidae), from the west coast of Portugal

Data on the juvenile recruitment, growth and size at maturation of Lipophrys pholis in Portuguese waters are compared with the information available on the biology of this species at higher latitudes. In Portugal, recruitment extends for a much longer period, young fish grow faster and sexual maturation is earlier than at higher latitudes. There is a delay of 2–3 months between the appearance of the first eggs on the shore and the recruitment of the first juveniles to the pools.     

Stephanostomum lophii sp. nov. (Digenea: Acanthocolpidae), intestinal parasite of Lophius piscatorius, with reference to seasonal fluctuations of metacercariae in intermediate second hosts (Gadidae)

We describe the adult and metacercaria of a new species of digenetic trematode, Stephanostomum lophii sp. nov., an intestinal parasite of the angler fish, Lophius piscatorius . The species is distinguished from the similar Stephanostomum kovalevi by the numerous peristomial spines in the latter and from S. baccatum by the oral sucker being larger than the ventral sucker and by the fact that the principal intermediate hosts are gadids, not pleuronectids as in the case of Stephanostomum baccatum . We also report the prevalence of S. lophii metacercariae in various potential angler fish prey species caught off the coast of Galicia (NW Spain).     

Zschokkella mugilis N. Sp. (Myxosporea: Bivalvulida) from Mullets (Teleostei: Mugilidae) of Mediterranean Waters: Light and Electron Microscopic Description

A new Myxosporea, Zschokkella mugilis n. sp., was found in the gall bladder of several mugilids. It is distinguished from all previously reported Zschokkella from mugilids by the absence of valve ornamentation and from other species by the size of the spores. Prevalence of infection was 62.5% for Mugil capito, 70% for M. cephalus and 64.3% for Liza saliens. Plasmodia with rhizoids attached to epithelial cells appeared to compromise the host as evidenced in light and transmission electron micrographs presented herein. General ultrastructure and disporous sporogenesis of Z. mugilis resembled other Myxosporeans, but sporogonic cells did not seem to be formed in pansporoblasts.     

Ultrastructure of the extracutaneous pigment cells in the plaice (Pleuronectes platessa,L., Teleostei)

Summary The extracutaneous pigment cell system of the plaice (Pleuronectes platessa L.) was examined by light and electron microscopy in selected regions, including two cutaneous regions for comparison. The extracutaneous pigmentation consists of guanocytes and melanocytes with differing distributions within the body. The eyeless side lacks melanocytes. The pigment cells are differentiated as very flat elements with long processes. They display an affinity for loose connective tissue at boundary layers such as the peritoneal epithelium, organ capsules or blood vessels, to which they are parallelly arranged at a very constant distance. In some locations guanocytes are intimately associated with melanocytes forming reduced chromatophore units. Extracutaneous pigment cells are poor in mitochondria, endoplasmic reticulum, microfilaments, caveolae intracellulares, ribosomes and glycogen granules, all of which are more abundant in cutaneous pigment cells and pigment cells of the eye. In extracutaneous guanocytes the crystals are loosely arranged parallel to the cell surface, in cutaneous guanocytes perpendicular. Cells with rod-like vesicular cisternae are described as guanoblasts. No single pigment cell was found exhibiting different types of pigment granules. The varying colors of extracutaneous pigmentation arise from varying combinations of guanocytes and melanocytes in addition to the color of the tissue itself.In partial fulfillment for the degree of Doctor of Medicine under the direction of Prof. Dr. Dr. H.-R. Duncker (Giessen)