Comparative allometry growth of some marine fish digenetic trematodes

Allometric growth variation was compared for Plagioporus idoneus, Lepocreadium pegorchis, Opecoeloides furcatus, Bacciger israelensis, Aphanurus stossichi and Parahurleytrema trachinoti collected from East Mediterranean fishes. The pharynx, the oral and the ventral sucker diameters always showed a negative allometry. The other parameters tested were variable with the species. We study the effects of some environmental factors: the influence of the host species is analysed in Plagioporus idoneous, wich parasitizes Oblada melanura, Diplodus sargus and D. vulgaris and in Lepocreadium pegorchis, wich parasitizes Pagellus erythrinus, Lithognathus mormyrus and Spicara smaris; the influence of the microhabitat and the intensity of infection is analysed in Bacciger israelensis and Aphanurus stossichi, both parasites of Boops boops. We report significant differences with the host species, for the allometric growth of the testes; the effect of the microhabitat was revealed by the hindbody allometric value; no significant difference was detected in relation with the intensity of infection.

Desciption of Cribomazocraes travassosi n. sp. (Monogenea: Mazocraeidae), a fish parasite from the Atlantic Ocean

Cribomazocraes travassosi n. sp. is described from Harengula clupeola (Cuvier, 1829) from Rio de Janeiro, coast, Brazil. It differs from C. nagibinae, Mamaev, 1981 in the size and shape of opisthohaptor and lappet and in the smaller size of anchors. From C. bychowskyi it also differs in the extension of vittelaria. A key for the species of the genus is presented.

Two new genera of Paramphistomidae (Trematoda, Digenea) from freshwater fish of Rondônia State, Brazil

Two new genera and species of Paramphistomidae (Trematoda, Digenea) are described from freshwater fish of Rondônia State, Brazil. Pronamphistoma cichlasomae gen. et sp. nov. from Cichlasoma severum (Heckel) is characterized as having a small, robust body with an anterior collar-like expansion, diverticula within the wall of the oral sucker and vitellaria in lateral fanshaped configurations. Micramphistoma ministoma gen. et sp. nov. from Hypopomus sp lacks oral diverticula, has anteriorly situated parallel tests and a very small postero-ventral acebtabulum. Neither of the new forms closely resembles any known genus.

The Accessibility City. When Transport Infrastructure Matters in Urban Spatial Structure

Suburbanization is changing the urban spatial structure and less monocentric metropolitan regions are becoming the new urban reality. Focused only on centers, most works have studied these spatial changes neglecting the role of transport infrastructure and its related location model, the “accessibility city”, in which employment and population concentrate in low-density settlements and close to transport infrastructure. For the case of Barcelona, we consider this location model and study the population spatial structure between 1991 and 2006. The results reveal a mix between polycentricity and the accessibility city, with movements away from the main centers, but close to the transport infrastructure.

Iceberg transport technologies in spatial competition. Hotelling reborn

Transport costs in address models of differentiation are usually modeled as separable of the consumption commodity and with a parametric price. However, there are many sectors in an economy where such modeling is not satisfactory either because transportation is supplied under oligopolistic conditions or because there is a difference (loss) between the amount delivered at the point of production and the amount received at the point of consumption. This paper is a first attempt to tackle these issues proposing to study competition in spatial models using an iceberg-like transport cost technology allowing for concave and convex melting functions.

A new, automated, four-colour interphase FISH approach for the simultaneous detection of specific aneuploidies of diagnosis and prognosis significance in high hyperdiploid ALL

In hyperdiploid acute lymphoblastic leukaemia (ALL), the simultaneous occurrence of specific aneuploidies confers a more favourable outcome than hyperdiploidy alone. Interphase (I) FISH complements conventional cytogenetics (CC) through its sensitivity and ability to detect chromosome aberrations in non-dividing cells. To overcome the limits of manual I-FISH, we developed an automated four-colour I-FISH approach and assessed its ability to detect concurrent aneuploidies in ALL. I-FISH was performed using centromeric probes for chromosomes 4, 6, 10 and 17. Parameters established for automatic nucleus selection and signal detection were evaluated (3 controls). Cut-off values were determined (10 controls, 1000 nuclei/case). Combinations of aneuploidies were considered relevant when each aneuploidy was individually significant. Results obtained in 10 ALL patients (1500 nuclei/patient) were compared with those by CC. Various combinations of aneuploidies were identified. All clones detected by CC were observed by I-FISH. I-FISH revealed numerous additional abnormal clones, ranging between 0.1 % and 31.6%, based on the large number of nuclei evaluated. Four-colour automated I-FISH permits the identification of concurrent aneuploidies of prognostic significance in hyperdiploid ALL. Large numbers of cells can be analysed rapidly by this method. Owing to its high sensitivity, the method provides a powerful tool for the detection of small abnormal clones at diagnosis and during follow up. Compared to CC, it generates a more detailed cytogenetic picture, the biological and clinical significance of which merits further evaluation. Once optimised for a given set of probes, the system can be easily adapted for other probe combinations.

Rhipidocotyle gibsoni n. sp. from a Brazilian Freshwater Fish and Rhipidocotyle froesi n.sp. for r. baculum (linton, 1905) of Eckmann (1932) (Bucephalidae; Digenea)

Rhipidocotyle gibsoni n.sp. is described from Acestrorhynchus lacustris from Paraná River, brazil. It is most closely related to r. froesi n. sp. and to R. eckmanni in the shape of the cephalic hood, differing in the extent of the uterus, in the position of the vitelline follicles and in that the host is a freshwater fish. Rhipidocotyle froesi n. sp. is proposed for the marine specimens described by Eckmann (1932) as R. baculum (Linton, 1905).

Transport pathways in the malaria-infected erythrocyte: characterization and their use as potential targets for chemotherapy

The intraerythrocytic malarial parasite is involved in an extremely intensive anabolic activity while it resides in its metabolically quiescent host cell. The necessary fast uptake of nutrients and the discharge of waste product, are guaranteed by parasite-induced alterations of the constitutive transporters of the host cell and the production of new parallel pathways. The membrane of the host cell thus becomes permeable to phospholipids, purine bases and nucleosides, small non-electrolytes, anions and cations. When the new pathways are quantitatively unimportant, classical inhibitors of native transporters can be used to inhibit parasite growth. Several compounds were found to effectively inhibit the new pathways and consequently, parasite growth. The pathways have also been used to introduce cytotoxic agents. The parasitophorous membrane consists of channels which are highly permeable to small solutes and display no ion selectivity. Transport of some cations and anions across the parasite membrane is rapid and insensitive to classical inhibitors, and in some cases it is mediated by specific antiporters which respond to their respective inhibitors. Macromolecules have been shown to reach the parasitophorous space through a duct contiguous with the host cell membrane, and subsequently to be endocytosed at the parasite membrane. The simultaneous presence of the parasitophorous membrane channels and the duct, however, is incompatible with experimental evidences. No specific inhibitors were found as yet that would efficiently inhibit transport through the channels or the duct.

Monophyletic origin of multiple clonal lineages in an asexual fish (Poecilia formosa).

Despite the advantage of avoiding the costs of sexual reproduction, asexual vertebrates are very rare and often considered evolutionarily disadvantaged when compared to sexual species. Asexual species, however, may have advantages when colonizing (new) habitats or competing with sexual counterparts. They are also evolutionary older than expected, leaving the question whether asexual vertebrates are not only rare because of their 'inferior' mode of reproduction but also because of other reasons. A paradigmatic model system is the unisexual Amazon molly, Poecilia formosa, that arose by hybridization of the Atlantic molly, Poecilia mexicana, as the maternal ancestor, and the sailfin molly, Poecilia latipinna, as the paternal ancestor. Our extensive crossing experiments failed to resynthesize asexually reproducing (gynogenetic) hybrids confirming results of previous studies. However, by producing diploid eggs, female F(1) -hybrids showed apparent preadaptation to gynogenesis. In a range-wide analysis of mitochondrial sequences, we examined the origin of P. formosa. Our analyses point to very few or even a single origin(s) of its lineage, which is estimated to be approximately 120,000 years old. A monophyletic origin was supported from nuclear microsatellite data. Furthermore, a considerable degree of genetic variation, apparent by high levels of clonal microsatellite diversity, was found. Our molecular phylogenetic evidence and the failure to resynthesize the gynogenetic P. formosa together with the old age of the species indicate that some unisexual vertebrates might be rare not because they suffer the long-term consequences of clonal reproduction but because they are only very rarely formed as a result of complex genetic preconditions necessary to produce viable and fertile clonal genomes and phenotypes ('rare formation hypothesis').

Elevated resource availability sufficient to turn opportunistic into virulent fish pathogens.

There is mounting evidence that organic or inorganic enrichment of aquatic environments increases the risk of infectious diseases, with disease agents ranging from helminth parasites to fungal, bacterial, and viral pathogens. The causal link between microbial resource availability and disease risk is thought to be complex and, in the case of so-called "opportunistic pathogens," to involve additional stressors that weaken host resistance (e.g., temperature shifts or oxygen deficiencies). In contrast to this perception, our experiment shows that the link between resource levels and infection of fish embryos can be very direct: increased resource availability can transform benign microbial communities into virulent ones. We find that embryos can be harmed before further stresses (e.g., oxygen depletion) weaken them, and treatment with antibiotics and fungicides cancels the detrimental effects. The changed characteristics of symbiotic microbial communities could simply reflect density-dependent relationships or be due to a transition in life-history strategy. Our findings demonstrate that simple microhabitat changes can be sufficient to turn "opportunistic" into virulent pathogens.

Neotropical Monogenoidea. 23. Two new species of Gyrodactylus (Gyrodactylidae) from a Cichlid and an Erythrinid fish of Southeastern Brazil

Two new species of Gyrodactylus Nordmann, 1832 (Platyhelminthes, Monogenoidea) are described from fishes collected from southeastern Brazil. Gyrodactylus geophagensis n. sp. was collected from the body surface of the "cará", Geophagus brasiliensis (Quoy and Gaimard, 1824) (Cichlidae), from the Rio da Guarda, state of Rio de Janeiro; its major diagnostic features are the morphology of the anchor with a short, truncate superficial root and the shape of the hooks - with a long, delicate shaft. Gyrodactylus trairae n. sp. parasitizes the body surface of the "traíra", Hoplias aff. malabaricus (Bloch, 1794) (Erythrinidae), from the rio Guandu, state of Rio de Janeiro and can be easily differentiated from other species of the genus by having a thin, dorsal bridge, connecting the superficial bar with the spathulated shield. These are the first species of Gyrodactylus formally reported from Brazil. Presently, 26 species of Gyrodactylidae are known from freshwater fishes in the neotropical region; a list of these species is provided.

A Redescription of Riggia paranensis Szidat, 1948 (Isopoda, Cymothoidae) Based on Thirty-two Specimens from Curimatid Fish of Rio de Janeiro, Brazil, with an Emendation of the Genus

Riggia paranensis Szidat, 1948 is redescribed on the basis of 30 female and 2 male specimens collected from the pericardial cavities of the curimatid fish Cyphocarax (= Curimata) gilberti (Quoy & Gaimard). The fishes were caught in the Itabapoana River, State of Rio de Janeiro, southeastern Brazil. The presence of" dwarf" males, as reported by Szidat, was verified. The fusion of the pleonites and pleotelson in adult females was also confirmed. The generic diagnosis was emended to include details of the mouthparts and pleopods