Molecular phylogeny of species of Ligophorus (Monogenea: Dactylogyridae) and their affinities within the Dactylogyridae

The taxonomic framework of Ligophorus, monogenean specialists of the gills of grey mullets (Mugilidae), is evaluated and its interspecific relationships are assessed for the first time using molecular data. The position of Ligophorus within the paraphyletic Ancyrocephalinae is re-assessed based on newly sequenced species. Furthermore, the relationship between morphometric and genetic interspecific similarities is evaluated. Partial 28S and complete ITS1 rDNA sequences from representatives of 14 of the 16 nominal species of Ligophorus from the Mediterranean, Black and Azov Seas were analysed together with published sequences of members of the Dactylogyridae. The phylogenetic analyses of the Dactylogyridae (i) confirmed the position of Ligophorus within the marine Ancyrocephalinae; (ii) revealed a sister relationship between Ergenstrema and Ligophorus, whose species are all exclusive parasites of grey mullets; and (iii) substantiated the affinities of Ergenstrema with the marine Ancyrocephalinae. The phylogenetic analysis restricted to Ligophorus confirmed the distinct status of the included species. The ITS1 region provided the highest divergence between species and phylograms with the strongest branch support. Both the 28S and ITS1 phylograms revealed two main clades. One included species from hosts with Mediterranean and NE Atlantic distribution and another was formed by species parasitising several Liza spp., including Lz. haematocheilus from the Northwestern Pacific, and Mugil cephalus, which suggests an origin outside the Mediterranean for the latter clade. The phylogenetic evidence presented herein indicated that a combination of host-switching and lineage duplication events accounted for the diversification of this genus in the Mediterranean basin. The agreement between molecular and morphological interspecific similarities observed in Ligophorus supports the validity of morphometric characters used for species identification.     

A revision of the Haploporinae Nicoll, 1914 (Digenea: Haploporidae) from mullets (Mugilidae): two new haploporine genera and a key to the genera of the subfamily

Two new haploporine genera are established for parasites of mullets. Ragaia n. g. is erected for R. lizae n. sp. from Liza ramado in the Ebro Delta on the Mediterranean Coast of Spain. This new genus is distinguished by the unique combination of the following characters: a strongly muscular ventral sucker which is twice as large as the oral sucker; a large, muscular hermaphroditic sac similar in length to the ventral sucker; a saccular, thick-walled internal seminal vesicle which is larger than the external seminal vesicle; and the ovary and vitellarium located rather close to the posterior extremity. Pseudodicrogaster n. g. is erected to accommodate Dicrogaster japonica Machida, 1996, as P. japonica (Machida, 1996) n. comb., a parasite of Mugil cephalus L. off Fukaura, Japan. This genus is recognised on the basis of: the tubular condition of both the internal and external seminal vesicles, the latter being much shorter than the former; the sucker ratio; the massive pyriform hermaphroditic sac; the location of the testis; and the presence of two eye-spots in developed miracidia. A key to the nine recognised genera of the Haploporinae is presented.

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A revision of the Haploporinae Nicoll, 1914 (Digenea: Haploporidae) from mullets (Mugilidae): <Emphasis Type="Italic">Saccocoelium</Emphasis> Looss, 1902

Saccocoelium Looss, 1902 is revised and a key to its recognised species is presented. S. obesum Looss, 1902 (type-species) and S. tensum Looss, 1902 are redescribed based on material from Liza spp. (Pisces: Mugilidae) in Spanish Mediterranean and, in the case of the former, Bulgarian Black Sea waters. Two new species, S. cephali n. sp. and S. currani n. sp., are described from Mugil cephalus L. in Spanish Mediterranean waters. S. gohari Ramadan, Saoud, Ashour & Mansour, 1989b is recognised and commented upon. Lecithobotrys helmymohamedi Ramadan, Saoud, Ashour & Mansour, 1989a, S. portsaidensis El-Shahawi, El-Gindy, Imam & Al-Bassel, 1992, S. saoudi El-Shahawi, El-Gindy, Imam & Al-Bassel, 1992, Neosaccocoelium aegyptiacus El-Shahawi, El-Gindy, Imam & Al-Bassel, 1992 are considered to be synonyms of S. tensum and Neosaccocoelium El-Shahawi, El-Gindy, Imam & Al-Bassel, 1992 a synonym of Saccocoelium. S. obesum, S. tensum and the two new species are compared morphometrically and distinguished by univariate and multivariate analyses. Lecithobotrys mugilis Rekharani & Madhavi, 1985 is transferred to Unisaccus Martin, 1973 as U. mugilis (Rekharani & Madhavi, 1985) n. comb., and Lecithobotrys sprenti Martin, 1973 [=  Saccocoelium sprenti (Martin, 1973) Overstreet & Curran, 2005] is transferred to Unisaccus as U. sprenti (Martin, 1973) n. comb. S. megasacculum Liu, Wang, Peng, Yu & Yang, 2004 is transferred to Elliptobursa Wu, Lu & Zhu, 1996 as E. megasacculum (Liu, Wang, Peng, Yu & Yang, 2004) n. comb. S. tripathi Dutta, 1995 (syn. Saccocoelium tripathi Datta & Manna, 1998) is considered to be a species inquirenda.

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IAA, ABA, polyamines and free amino acids associated with zygotic embryo development of Ocotea catharinensis

The aim of this work was to study morphological and biochemical aspects during zygotic embryogenesis in O. catharinensis, by measuring changes in the endogenous concentrations of proteins, amino acids, polyamines (PAs), indole-3-acetic acid (IAA) and abscisic acid (ABA). Buffer-soluble and insoluble protein contents were determined by spectrometry, and amino acids, PAs, IAA and ABA concentrations were determined by high performance liquid chromatography. Total amino acid accumulation, predominantly asparagine, occurred when the embryo showed completely developed cotyledons, with posterior reduction in the mature embryo. This decrease in total amino acid concentration in the mature embryo may result from their use in storage␣as well as for LEA protein synthesis. Free putrescine (Put) concentration decreased, while free spermine (Spm) increased during embryo development. This suggest a role for Put in the initial phases of embryogenesis when high rates of cell division occur, while elevated concentration of Spm are essential from the middle to the end of embryo development, when growth is mainly due to cell elongation. An IAA peak in zygotic embryos occurred during initial development, suggesting a link between growth and cellular division as well as with the establishment of bilateral symmetry. ABA concentration declined during initial stages of development then increased at the mature embryo stage, suggesting a possible relationship with dormancy and recalcitrance characteristics. Our results show that changes in the phytohormones (IAA, ABA and PAs) concentrations in combination with amino acids are likely important factors determining the developmental stages of O.␣catharinensis zygotic embryos.     

CYP11A1 stimulates the hydroxylase activity of CYP11B1 in mitochondria of recombinant yeast in vivo and in vitro.

In mammals, hydrocortisone synthesis from cholesterol is catalyzed by a set of five specialized enzymes, four of them belonging to the superfamily of cytochrome P-450 monooxygenases. A recombinant yeast expression system was recently developed for the CYP11B1 (P45011beta) enzyme, which performs the 11beta hydroxylation of steroids such as 11-deoxycortisol into hydrocortisone, one of the three mitochondrial cytochrome P-450 proteins involved in steroidogenesis in mammals. This heterologous system was used to test the potential interaction between CYP11B1 and CYP11A1 (P450scc), the mitochondrial cytochrome P-450 enzyme responsible for the side chain cleaving of cholesterol. Recombinant CYP11B1 and CYP11A1 were targeted to Saccharomyces cerevisiae mitochondria using the yeast cytochrome oxidase subunit 6 mitochondrial presequence fused to the mature form of the two proteins. In yeast, the presence of CYP11A1 appears to improve 11beta hydroxylase activity of CYP11B1 in vivo and in vitro. Fractionation experiments indicate the presence of the two proteins in the same membrane fractions, i.e. inner membrane and contact sites of mitochondria. Thus, yeast mitochondria provide interesting insights to study some molecular and cellular aspects of mammalian steroid synthesis. In particular, recombinant yeast should permit a better understanding of the mechanism permitting the synthesis of steroids (sex steroids, mineralocorticoids and glucocorticoids) with a minimal set of enzymes at physiological level, thus avoiding disease states.     

Growth and emigration of third-stage larvae of Hysterothylacium aduncum (Nematoda: Anisakidae) in larval herring Clupea harengus

The growth and emigration of Hystherothylacium aduncum in laboratory-reared herring larvae Clupea harengus was studied. Experimental infections of 36-day-old herring larvae resulted in 126 hosts infected with 306 H. aduncum larvae. Regression analyses showed a significant worm emigration from the rectum to the head of the fish, accompanied by an increase in worm body length. The emigration was independent of worm intensity, which suggests an ontogenetic process. Some worms departed from this pattern by moving posteriorly or by penetrating into the muscle, and in 5 cases, the larvae were observed to leave living fish. This individual variation has not been observed in previous studies and might be explained by host signals related to condition or development stage. Indirect evidence suggested parasite-induced mortality in the tanks due to the emigrations because only 4 of the 126 infected fish survived 8 days postinfection; the emigration of H. aduncum affected vital organs, such as the heart and brain, and the larvae penetrating or leaving the host's tissues can cause extensive damage to the delicate herring larvae.     

Population structure of Anisakis simplex (Nematoda) in harbor porpoises Phocoena phocoena off Denmark

The population structure and habitat selection of Anisakis simplex in 35 harbor porpoises off Denmark are described. The nematodes were collected from the stomach and duodenal ampulla and were categorized as third-stage larvae, fourth-stage larvae, subadults, and adults. The porpoises harbored 8,043 specimens of A. simplex. The proportion of adults and subadults increased with infrapopulation size. The number of development stages across infrapopulations covaried significantly (Kendall's test of concordance). Concordance was higher in hosts with the highest intensities than in those with low and medium intensities. All stages occurred mainly in the forestomach, but this trend was stronger for the adults. Adult and subadult sex ratios did not depart significantly from 1:1. Our data suggested that recruitment and duration of each stage were the main factors accounting for infrapopulation structure. The preference of A. simplex for the forestomach conformed with previous studies, but the narrower distribution of adults relative to other stages might indicate a strategy to enhance mating opportunities. Information on sex ratios of A. simplex is scarce and contradictory. We suggest that the discrepancies might partly reflect differences in categorization criteria and statistical methods.     

A new species of the genus Zalophotrema (Digenea: Campulidae), Zalophotrema atlanticum n. sp., from the liver of the striped dolphin Stenella coeruleoalba (Meyen, 1833) (Cetacea: Delphinidae) in Atlantic waters

Zalophotrema atlanticum n. sp. from the liver of a striped dolphin, Stenella coeruleoalba (Meyen, 1833), stranded in the Canary Islands is described. This new species differs from the other Zalophotrema species in body dimensions and relative size and position of the suckers and cirrus-sac. This is the first record of a species of the genus Zalophotrema in the striped dolphin, and the Atlantic Ocean constitutes a new locality record for this genus.