Redescription de Proteocephalus paraguayensis (Rudin, 1917) (Cestoda: Proteocephalidae) parasite de Hydrodynastes gigas (Dum., Bibr. & Dum., 1854) du Paraguay

Redescripción de Proteocephalus paraguayensis (Rudin, 1917) (Cestoda: Proteocephalidae), parásito de Hydrodynastes gigas (Dum., Bibr. & Dum., 1854) de Paraguay. Se describe esta especie notable, considerada por Freze (1965) como species inquirenda. Si comparamos esta especie con otras especies de Proteocephalidea, veremos que ella presenta caracteres anatomo-morfológicos propios. Esta especie se caracteriza por: vitelógenos de posición dorsal, adosados a la musculatura interna longitudinal, desbordando en parte sobre el córtex y la médula; formación particular del útero; posición cortical del tronco uterino y medular de los divertículos uterinos; esfínter vaginal proximal; cirro muy alargado; glándula de Mehlis muy desarrollada. Consideramos P. paraguayensis como una especie válida y presumimos que el huesped-tipo es Hydrodynastes gigas (Dum., Bibr. & Dum., 1854). A pesar de las características que posee P. paraguayensis, pensamos que no es oportuno clasificar esta especie en un nuevo género monotípico. Proteocephalus paraguayensis, considered by Freze (1965) as a species inquirenda, is redescribed and figured. When compared with other members of the Proteocephalidea, the species shows the following morpho-anatomical characters: the vitelline follicles in a dorsal position, attached to the internal longitudinal musculature and extending into both the cortex and medulla; a characteristic formation of the uterus; the uterine stem in a cortical position and uterine branches in a medullary position; a proximal vaginal sphincter; a very elongate cirrus; and very large Mehlis' glands. The specific status of Proteocephalus paraguayensis is confirmed. Our specimens were taken from Hydrodynastes gigas (the host according to Rudin was Coluber sp.). Even though the species differs significantly from other proteocephalideans, its systematic and phylogenetic position is not yet clearly demonstrated, and it is decided to refrain from attributing it to a new genus.     

Monogènes Dactylogyridae parasites de Cyprinidae du genreBarbus d'Afrique du Nord

Resumé Quinze nouvelles espèces de Monogènes Dactylogyridae sont décrites chez quinze espèces deBarbus (Teleostei, Cyprinidae) appartenant aux sous-genresB. (Barbus) etB. (Labeobarbus) en Afrique du Nord. Les barbeaux examinés proviennent des différents bassins hydrographiques du Maroc et d'une localité nommée Hamman Bourgiba en Tunisie. Dans cette dernière région, le genreBarbus n'est représenté que par une seule espèce:Barbus (B.) callensis. Au Maroc, on en dénombre actuellement quatorze dont quatre appartiennent au sous-genreLabeobarbus: il s'agit deBarbus (L.) fritschii; B. (L.) harteti; B. (L.) paytonii etB. (L.) reinii. Les dix espèces appartenant au sous-genreBarbus sont:Barbus (B.) figuiensis; B. (B.) ksibi; B. (B.) lepineyi; B. (B.) magniatlantis; B. (B.) massaensis; B. (B.) moulouyensis; B. (B.) nasus; B. (B.) pallaryi; B. (B.) setivemensis etB. (B.) issenensis.Chaque sous-genre possède son propre pool parasitaire, à l'exception deDactylogyrus marocanus n. sp., recontré sur des espèces appartenant aux deux sous-genres (B. (L.) fritschii, B. (L.) paytonii, B. (L.) harteti, B. (L.) reinii, B. (L.) nasus, B. (B.) setivimensis, B. (B.) ksibi). Sur les cinqDactylogyrus parasitant lesLabeobarbus, trois présentent une spécificité stricte vis à vis de leur hôte. Il s'agit deDactylogyrus reinii n. sp. surB. (L.) reinii; D. volutus n. sp. etD. zatensis n. sp. surB. (L.) fritschii. Les espècesD. oumiensis n. sp. etD. kulindrii n. sp. présentent une spécifité stenoxène et parasitent respectivementB. (L.) harteti, B. (L.) paytonii, B. (L.) reinii etB. (L.) fritschii, B. (L.) reinii.Nous avons recontré neufDactylogyrus chez les poisson-hôtes appartenent au sous-genreBarbus. Six d'entre eux ont une spécificité oïoxène; ce sont:D. guirensis n. sp.,D. atlasensis n. sp. etD. draaensis n. sp. surB. (B.) pallaryi; D. borjensis n. sp. surB. (B.) nasus etD. heteromorphus n. sp. etD. tunisiensis n. sp. surB. (B.) callensis. Les trois autres parasites ont un spectre d'hôtes plus large. Il s'agit deD. ksibii n. sp. recontré chezB. (B.) ksibi, B. (B.) setivimensis etB. (B.) magniatlantis; D. ksibioïdes n. sp. recontré chezB. (B.) setivimensis etB. (B.) moulouyensis. L'espèceD. fimbriphallus n. sp. stenoxène, se recontre chez les poisson-hôtes du versant Sud de l'Atlas et de la façade méditerranéenne à savoir:B. (B.) figuiensis, B. (B.) lepineyi, B. (B.) massaensis, B. (B.) moulouyensis, B. (B.) pallaryi etB. (B.) issenensis.Le rôle des Dactylogyridae en tant que marqueurs biogéographiques, phylogénétiques et taxonomiques est discuté à partir de la composition spécifique des communautés de Monogènes rencontrés et de leurs différents types morphologiques.

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Fifteen new species of the Dactylogyridae (Monogenea) parasitic on fifteen species of barbels (Barbus) from North Africa (Teleostei, Cyprinidae) are described. The fishes studied belong to two subgenera,B. (Labeobarbus) andB. (Barbus), collected from various hydrographical basins of Morocco and from the Hamman Bourgiba locality in Tunisia. In the latter area, the genusBarbus is represented by onlyBarbus (Barbus) callensis. In Morocco, fourteen species are listed, four of which belong to the subgenusLabeobarbus; these areBarbus (L.) fritschii; B. (L.) harteti; B. (L.) paytonii andB. (L.) reinii. The other ten species belong to the subgenusBarbus: these areBarbus (B.) figuiensis; B. (B.) ksibi; B. (B.) lepineyi; B. (B.) magniatlantis; B. (B.) massaensis; B. (B.) moulouyensis; B. (B.) nasus; B. (B.) pallaryi; B. (B.) setivimensis andB. (B.) issenensis. Each of the two subgenera has its unique parasitic fauna, except forDactylogyrus marocanus n. sp. collected on species belonging to both subgenera (B. (L.) fritschii, B. (L.) paytonii, B. (L.) harteti, B. (L.) reinii, B. (B.) nasus, B. (B.) setivimensis andB. (B.) ksibi). Of the five monogeneans found onLabeobarbus, three appear to be specific to one host: they areDactylogyrus reinii n. sp. onB. (L.) reinii, andD. volutus n. sp. andD. zatensis n. sp. onB. (L.) fritschii. D. kulindrii n. sp. parasitisedB. (L.) reinii andB. (L.) fritschii; andD. oumiensis n. sp. occurred onB. (L.) reinii, B. (L.) paytonii andB. (L.) harteti. NineDactylogyrus species were found in fishes belonging to the subgenusBarbus. Six of them have an oïoxenous specificity: these areD. guirensis n. sp.,D. atlasensis n. sp. andD. draaensis n. sp. onB. (B.) pallaryi; D. borjensis n. sp. onB. (B.) nasus andD. heteromorphus n. sp. andD. tunisiensis n. sp. on(B.) callensis. These other three have a wider range of hosts: they areD. ksibii n. sp. collected fromB. (B.) ksibi, B. (B.) setivimensis andB. (B.) magniatlantis, andD. ksibioïdes n. sp. found onB. (B.) setivimensis andB. (B.) moulouyensis. D. fimbriphallus n. sp. is a characteristic parasite of fishes from the southern side of the Atlas mountains and the Mediterranean coast (B. (B.) figuiensis, B. (B.) lepineyi, B. (B.) massaensis, B. (B.) moulouyensis, B. (B.) pallaryi andB. (B.) issenensis).The role of dactylogyrids as biogeographical phylogenetic and taxonomic indicators is discussed in relation to the specific structure of the monogenean communities and the different morphological types found.

     

Uptake,accumulation and metabolism of auxins in tobacco leaf protoplasts

Uptake and metabolism of exogenous naphthalene-1-acetic acid (NAA) and indole-3-acetic acid (IAA) have been studied in tobacco (Nicotiana tabacum L. cv. Xanthi) mesophyll protoplasts. Both auxins entered protoplasts by diffusion under the action of the transmembrane pH gradient without any detectable participation of an influx carrier. Molecules were accumulated by an anion-trapping mechanism and most of them were metabolized within hours, essentially as glucose-ester and amino-acid conjugates. Protoplasts were equipped with a functional auxin-efflux carrier as evidenced by the inhibitory effect of naphthylphtalamic acid on IAA efflux. Basically, similar mechanisms of NAA and IAA uptake occurred in protoplasts. However, the two auxins differed in their levels of accumulation, due to different membrane-transport characteristics, and the nature of the metabolites produced. This shows the need to estimate the accumulation and the metabolism of auxins when analyzing their effects in a given cell system. The internal auxin concentration could be modulated by changing the transmembrane pH gradient, giving an interesting perspective for discriminating between the effects of intra- and extracellular auxin on physiological processes.Abbreviations BA benzoic acid - C_i/C_e accumulation ratio of auxin - IAAasp N-[3-indolylacetyl]-dl-aspartic acid - NAA naphthalene-1-acetic acid - NAAasp N-[1-naphthylacetyl]-l-aspartic acid - NPA N-1-naphthylphthalamic acid The authors thank Dr. M. Caboche (I.N.R.A, Versailles, France) for his generous gifts of some amide derivatives of 1-NAA, Mr. P. Varennes and Dr. B. Das (I.C.S.N., C.N.R.S., Gif-sur-Yvette, France) for recording and interpreting the mass spectra of NAA glucose ester, and Prof. P. Manigault (Institut des Sciences Végétales, Gif-sur-Yvette) for microscopy measurements of protoplast dimensions. This work was supported by funds from the C.N.R.S, I.N.R.A, and E.E.C.     

Xcp-mediated protein secretion in Pseudomonas aeruginosa: identification of two additional genes and evidence for regulation of xcp gene expression

In Pseudomonas aeruginosa, several exoproteins synthesized with a signal sequence (elastase, lipase, phospholipases, alkaline phosphatase and exotoxin A) are secreted by a two-step mechanism. They first cross the inner membrane in a signal sequence-dependent way, and are further translocated across the outer membrane in a second step requiring secretion functions encoded by several xcp genes. Ten xcp genes have already been characterized (Bally et al., 1992a). In this study, two additional xcp genes, xcpP and xcpQ, are described. They are located in the 40 min region of the chromosome where they probably define an operon, divergent from the xcpR–Z operon previously characterized in this region. These two genes encode two proteins, XcpP and XcpQ, similar to PulC and PulD of the pul system of Klebsiella oxytoca. Moreover, the two divergent operons share a common regulation which is growth-phase dependent.     

Spatial components of foraging behavior in an African Ponerine ant,Paltothyreus tarsatus

Colonies of the African stink ant Paltothyreus tarsatuslocated in the forest have nests with shorter horizontal galleries and a smaller total foraging surface than colonies located in open areas. Each solitary worker specializes on the same central or peripheral hunting zone but she does not specialize on a particular sector during group-retrieving. The search for prey is characterized by a wandering walk with spatial parameters varying in two ways. Capture of a termite releases a path characterized by sinuosity and a decrease in speed of movement. In contrast, a failure in the course of an attempted capture releases an increase in both sinuosity and speed of movement corresponding to a socalled reserve behavior. Each worker shortens her retrieving trip in comparison with her search trip and the straightness of the homing paths depends on the size and shape of the prey. Our data show that behavioral flexibility at the individual level in P. tarsatusis important in determining spatial foraging strategy at the colony level.     

Actin and spectrin-like (Mr= 260–240 000) proteins in gregarines

In Gregarina blaberae a M_r = 47 000 and a M_r = 260–240 000 doublet polypeptides reacted in immunoblotting: i) with a polyclonal monospecific rabbit antibody to frog muscular actin, a monoclonal anti-actin antibody against chicken gizzard; and ii) with polyclonal and monoclonal antibodies to human erythrocyte β-spectrin, respectively. The M_r = 47 000 actin-like protein is associated with the ghost and a contractille cytoplasmic extract. The presence of an actin-like protein in Gregarina and Lecudina and its cellular distribution in the cortex indicated that the gliding movement might involve an actin-myosin system in contrast to previous studies. Immunofluorescence showed clear differences between the anterior part of Gregarina and Lecudina which illustrated the high cell polarity of these protozoa. The M_r = 260–240 000 doublet was detected in SDS-PAGE from G. blaberae trophozoite ghosts but not in the cytoplasmic extracts or in extracts from sexual stages, indicating that the presence of these spectrin-like proteins is stage-dependent. Visualization of the M_r = 260–240 000 by immunofluorescence showed clear species differences, with rings arranged perpendicular to the longitudinal narrow folds of G. blaberae, with longitudinal lines underlying the folds of L. pellucida and with lines separating the large folds of Selenidium pendula. The cellular distribution is consistent with a stabilizer function of the spectrin-like proteins in the scaffolding of the cortex of gregarines according to the high diversity of the cell-shape and the cell motility systems in gregarines. The presence of spectrin-like proteins in protozoa and particularly in parasites from primitive arthropods indicated that ancestral spectrin genes could the M_r = 260–240 000 form.