Locomotion in Nebalia bipes: a possible model for Palaeozoic phyllocarid crustaceans

The morphofunctional aspects of locomotion in Recent phyllocarid crustaceans are presented, based on combined video observations of living specimens of the cosmopolitan nektobenthic Nebalia (Leptostraca, Nebaliidae) and scanning electron microscopy of fixed material. N. bipes is infaunal by day, showing a preference for organic-rich black muds and dim light conditions. Under natural conditions, emergence from sediment and nocturnal swimming activities are controlled by a circadian rhythm. The 1st and 2nd antennae perform the major role in digging. The carapace rostral plate acts as a ram diverting particles and preventing inputs of sediment into the carapace. Superficial burrowing may provide camouflaged shelter against predation. Swimming is accomplished by the combined action of the first four pairs of pleopods (backward metachronal flexion during the power stroke) and the well-articulated abdominal shaft (downward flap). Plumose setae present on both the pleopods and furcal rami (governed by low Reynolds numbers) behave like paddles maximizing the resistance to the water. Clusters of cuticular microscales (3-5 μm) and microdenticles are present on the external surface of the carapace and the trunk segments, respectively. Both show a uniform directional arrangement suggesting functional interpretations in relation to locomotion (e.g., to prevent back slippage during digging, to reduce turbulence in the flow layer close to the body, and/or to serve as mechanoreceptors for the detection of variation in water flow). Key features of functional importance in the locomotion of living leptostracans (natatory pleopods, a highly flexible abdomen, setulate or paddle-like furcal rami) are also recognized in Palaeozoic archaeostracan phyllocarids, suggesting that swimming was accomplished by the same pleopodal movements as described for N. bipes. Comparisons with Recent analogues (Nebaliopsis) suggest that phyllocarids with a free swimming life-style existed among the lower Palaeozoic archaeostracans (e.g., Caryocaris; Ordovician). Asymmetrical cuticular ornament in some archaeostracans indicates burrowing habits. Some Palaeozoic phyllocarids may have been occasional (possibly diurnal) mud dwellers comparable to modern nebaliids.     

The Cambrian origin of the circulatory system of crustaceans

The carapace of Recent crustaceans such as myodocope ostracodes and phyllocarids is pervaded with well-developed anastomosing sinuses conveying hemolymph from the metabolizing organs to the dorsal heart. The inner lamella cuticle, which separates the sinuses from seawater, is thin enough to allow gaseous diffusion (e.g., O₂ uptake) over its surface. Comparable radiating and/or anastomosing features, of possible vascular origin, are herein recognized in several possible Crustacea from the Cambrian: cambriid, svealutiid, hipponicharionid and beyrichonid Bradoriida and in Carnarvonia from the middle Cambrian Burgess Shale. The vascular network is basically the same in these groups, consisting of sinuses radiating from supposed adductorial areas or from inferred areas of dorsal attachment of the body. The integumental (carapace sinuses) and branchial (gills) systems of respiration in crustaceans and crustacean-like animals were probably already differentiated by the middle Cambrian. The oldest record of probable integumental circulation is in the bradoriid Petrianna from the early Cambrian of Greenland. Similar circulatory systems may be represented by radiating ridges on the cephalon of other Cambrian arthropod groups such as the arachnomorphs ( Burgessia ) and trilobites ( Naraioa ) and may also be manifest in the carapaces of Ordovician-Devonian leperditicope ostracodes. Organs on the thoracopods of Cambrian supposed crustaceans, such as Canadaspis , resemble the foliaceous thoracic gills of Recent nebaliid phyllocarids and therefore may have served the same (respiratory) function.     

Étude morphologique et anatomiquede Rhynchonelloidea ruthenensis (Reynès, 1868) justification de la distinction des genres Rhynchonelloidea Buckman, 1914 et Homoeorhynchia Buckman, 1914 (Brachiopoda)

In the course of researches on the fauna of «calcaires bajociens á bryozoaires of Aveyron départment (France), numerous collects of shells named Rhynchonelloidea ruthenensis (Reynès), type-species of genus RhynchonelloideaBuckman, in two localities enabled to do a morphologic study of this species with populations analysis. Internal characters have been shown both by serial sections and by direct observation of dissected shells. A comparison of genus Rhynchonelloidea and Homoeorhynchia, till now either distinct or considered synonymous according to authors, has been realised. Internal characters of Homoeorhynchia acuta (Sow.) have been precised. The two genus are distinct by beak and foramen's characters, by presence or lack of costulation on the beak and dorsal umbo, by the number of ribs, by presence or lack of septalium and by the development of median dorsal septum.The stratigraphical range of R. ruthenensis is:Upper Toarcian, Aalensis zone-Lower Aalenian, Opalinum zone.     

Variabilité biochimique et génétique de Sphaeroma ghigii,S. hookeri et S. serratum. Comparaison interspécifique

Total proteins, esterases and phosphatases in Sphaeroma ghigii, S. hookeri and S. serratum (Crustacea: Isopoda Flabellifera) were compared by electrophoresis on polyacrylamide gels. Interspecific variations were found which may be useful in taxonomic problems. On the one hand, there are a number of protein and enzyme fractions in each species which differ from each other as well as species specific patterns. On the other hand, the results show some molecular homology which may be interpreted at the phyletic level. Vavilov's law of homologous variation indicates that the interspecific distance between Sphaeroma hookeri and S. ghigii is smaller than between these two species and S. serratum.     

Pecopteris (Asterotheca) saraeiP. Corsin, 1951, forme fertile de Sphenopteris damesii (Stur, 1885)

Sphenopteris damesii (Stur), a rather frequentspecies from the Sarre-Lorraine Coalfield was only known till now as a typical sphenopteridian sterile foliage. The study of a lot of specimens from recent boreholes has allowed us to show the great polymorphism of this species whose foliage, usually deeply dissected, tends to be pecopteridian in the fertile stage.The organization of fructifications and the type of included spores are described for the first time. Moreover, the comparison of the fertile specimens of Sph. damesii with those from the same horizon described by P. Corsin as Pecopteris saraei has revealed similarity in limb morphology, in the organization of fructifications, in the type of spores which proves that P. saraei is the fertile form of Sp. damesii. Consequently, P. Corsin's species is a posterior synonym of Sphenopteris damesii (Stur).The generic attribution of this species sets a nomenclatural question: the features of the fructifications agree exactly with the diagnose of the genus AsterothecaPresl but this genus till now was reserved for sporangia born by typical pecopteridian foliage. Nevertheless, the species is temporarily refered to Asterotheca until further works allow to decide about the subordination of these different characters.     

Sensitivity and adaptation in the Drosophila phototransduction and photoreceptor degeneration mutants trp and rdgB

We studied rdgB, a retinal degeneration mutant, and trp, a phototransduction mutant, separately and in combination in Drosophila. First we showed that trp did not block degeneration in white-eyed rdgB mutants. Thus, rdgB was useful in determining the defects which trp caused in the compound eye receptors R7 and R8; this is because rdgB selectively eliminates R1-6 photoreceptors which would, if present, dominate the compound eye responses. R7 and R8 both express the trptransient receptor potential phenotype in trp mutants. The trp mutation does not change receptor spectral sensitivities, nor does it alter the dark stability of R1-6's and R7's metarhodopsins as judged by dark adaptation studies. The dark adaptation is not significantly affected by trp. However, trp slows the dark adaptation of R8 considerably and seems to make the blue-induced inactivation of R1-6 less stable.     

Sur les fougères Anachoropteris et Tubicaulis du Stéphanienfrançais. Description de Tubicaulis grandeuryi nov. sp.

New information is presented on the morphology of leaves and stems of the ferns Anachoropteris and Tubicaulis preserved in silicified material from the Stephanian of Grand'Croix (France). A rachis of Anachoropteris involuta bears laterally, in association with a pinna, an epiphyllous stem, with a vitalized protostele. This stem bears nine petioles and is almost identical in anatomy to the american species, Tubicaulis stewartii. A hand-ground section from the Grand'Eury collection, Paris, is described as Tubicaulis sp. and identified as a more distal region of a similar stem. Tubicaulis grandeuryi nov. sp. is another type, with haplostelic stem and petioles bearing pinna traces near their base. Axillary branching is described in this genus for the first time. The problem of redefining the systematic position of Tubicaulis and its relationship to Anachoropteris is discussed.     

Parasitism of the mosquito Culex pipiens by the nematode Heterorhabditis bacteriophora

Various concentrations of the nematode Heterorhabditis bacteriophora were added to dishes containing second, third, and fourth larval instars of the mosquito, Culex pipiens, respectively. The infective stage nematodes were ingested by the mosquito larvae, they then penetrated through the alimentary tract in the neck region and entered the hemocoel. A melanization reaction killed many invading nematodes, but heavier concentrations overwhelmed the hosts' defense reaction and 100% mortality of third- and fourth-instar larvae was achieved using between 170 and 200 nematodes per host. Death was either due to the nematode releasing cells of the symbiotic bacterium, Xenorhabdus luminescens, into the hemocoel or to foreign bacteria (mostly Pseudomonas aeruginosa), which were introduced by the penetrating nematodes. The potential use of this nematode as a biological control agent of larval culicine mosquito is discussed.     

Crassostrea gryphoides et C. gingensis (Schlotheim, 1813) deux expressions morphologiques d'une même espèce (Miocène, Bivalvia)

The assemblages of Crassostrea gryphoïdes of the Loupian's quarry is constitued of differents morphotypes which result of ecological effects (population density, locality and position in the assemblage). The selection of individuals with her life position shows two lots of Ostreidae the morphology of which is statistically different. The observations about Crassostrea of outcrops of Rhone's Valley and Touraine confirm the relations between position (liable to population's density) and morphology. The two types which are point out are often recognize as different species describe by E.F. von Schlotheim, 1813: Crassostrea gryphoïdes and Crassostrea gingensis. Therefore this two species must be consider as synonymous.     

Antioxidant status of Lobiger serradifalci and Oxynoe olivacea (Opisthobranchia, Mollusca)

Invasion of the Mediterranean Sea by the two world-wide famous exotic algae species, Caulerpa taxifolia and Caulerpa racemosa, is still a problem and has adverse effects on the Mediterranean sublittoral ecosystem. Biological control studies revealed that the two native Sacoglossans, Oxynoe olivacea and Lobiger serradifalci, may have an effect on the expansion of invasive Caulerpa spp. in the Mediterranean. In the framework of this study, antioxidant enzyme activities, such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), lipid peroxidation (LPO) and oxidized glutathione (GSSG) levels, as oxidative stress markers in L. serradifalci and O. olivacea were determined at two different temperature conditions (20 and 27 °C). In both species, SOD, CAT and GSH-Px activities were found to be positively correlated with temperature. The SOD activities in L. serradifalci were higher than those in O. olivacea at both temperatures, whereas the CAT and GSH-Px activities were significantly (p<0.05) higher in O. olivacea, compared to L. serradifalci. As expected, both species showed decreased LPO levels at 27 °C compared to 20 °C. GSSG level at 27 °C in O.olivacea was significantly (p<0.05) higher than that of 20 °C. On the other hand, no statistical (p>0.05) difference in L.serradifalci existed between GSSG levels at two temperatures. But, despite the variations in the antioxidant enzyme activities, there was no significant difference in LPO levels between the species, suggesting that the oxidative consequences of a given environmental condition may vary among different species. Inasmuch as the GSSG levels were in accordance with antioxidant enzyme activities, GSH might have acted as a cofactor of GSH-Px and an individual antioxidant in these sea slugs.     

Nocturnal orientation by the Asian honey bee, Apis dorsata

Honey bees have been observed to forage and dance on moonlit nights, but it has never been established whether the moon serves as a reference in orienting nocturnally active bees. The present study, of the Asian honey bee Apis dorsata, suggests that although the moon's illumination is essential for nocturnal flight, the moon itself is ignored for orienting the dances. Rather, bees probably use the sun's position as a reference point for their dances, even though the sun is below the horizon. This ability may involve an extension of the mechanism that honey bees employ to find the sun on overcast days.     

Cloning and expression of boule and dazl in the Nile tilapia (Oreochromis niloticus)

The Deleted in Azoospermia (DAZ) family of RNA binding proteins consists of highly conserved genes boule, daz and daz-like (dazl) essential for germ cell development. boule is known for its unisexual meiotic expression in invertebrates and mammals, but meiotic-specific female expression plus meiosis-preferential male expression in trout, and meiosis-preferential bisexual expression in medaka. dazl shows highly conserved bisexual expression throughout gametogenesis in diverse species. Here we report the cloning and expression of boule and dazl in the Nile tilapia (Oreochromis niloticus), an important aquaculture fish. Molecular cloning and sequence analysis led to the identification of tilapia boule and dazl cDNAs. The predicted partial Boule contains a conserved RRM motif and Dazl has the C-terminal sequence. On a phylogenetic tree, tilapia Boule and Dazl are in separate clades of Boule and Dazl homologs from other species, indicating their divergence during early vertebrate evolution. By RT-PCR analysis, boule and dazl showed bisexual gonad-specific expression. By in situ hybridization analysis, both boule and dazl RNAs were restricted to female and male germ cells of adult gonads but absent in gonadal soma. In the ovary, boule and dazl RNAs were abundant in oocytes. In the testis, boule and dazl RNAs were prominent in meiotic spermatocytes but barely detectable in meiotic products. These data show that boule and dazl are expressed bisexually in germ cells and provide useful markers to study gametogenesis in the adult tilapia.     

Rare phyllocarid crustaceans from the Devonian Hunsrück Slate

Phyllocarids other thanNahecaris stuertzi are rare in the Hunsrück Slate. The few specimens, mostly fragmentary, are here described and referred to seven different taxa:Heroldina rhenana, Ceratiocarina fam. et gen. indet.,Montecaris? sp.,Nahecaris? halssi, Nahecaris sp.,Dithyrocaris? sp., and Rhinocarididae gen. et sp. indet. Almost none of them yields diagnostic characters permitting identification at even generic level. Some may be different body regions of the same taxon. The Hunsrück Slate phyllocarids, includingNahecaris, preserve characters which indicate an affinity with the leptostracan Malacostraca. Schram’s (1986) reassignment of the phyllocarids to the Class Phyllopoda is therefore rejected.     

Tannuaspis,Tuvaspis and Ilemoraspis,endemic osteostracan genera from the Silurian and Devonian of Tuva and Khakassia (USSR)

Three osteostracan genera, Tannuaspis, Tuvaspis and Ilemoraspis, from the Silurian and Devonian of the Autonomous Republic of Tuva and the Autonomous Region of Khakassia (USSR), are revised on the basis of the type material briefly described by Obruchev (1956, 1961, 1964). Tannuaspis bears some resemblances with the Tremataspididae. Tuvaspis may be closely related to Tannuaspis. Finally, there is no evidence of paired fins and cornual processes in Ilemoraspis (neither is there any evidence of their absence). Tannuaspis and Ilemoraspis share some characters which are not found in any other osteostracan: widely separated orbits, very small and oval lateral fields, situated at the same level as the median dorsal field. These resemblances may suggest that these two genera (to which Tuvaspis may be added) form a monophyletic group of osteostracans, which may be endemic to this part of Central Asia.     

Early development and microhabitat of the monogenean Horricauda rhinobatidis, with observations on the related Troglocephalus rhinobatidis, from Rhinobatos batillum from Queensland,Australia

The small monocotylid monogenean Horricauda rhinobatidis is abundant on the gills of its host Rhinobatos batillum, whereas the larger, related monogenean Troglocephalus rhinobatidis is comparatively uncommon. Young specimens of Horricauda live between the host's secondary gill lamellae. Post-oncomiracidia have 14 marginal booklets but as the larvae develop these are supplemented first by a pair of hamuli and then by muscular ventral loculi followed by six forwardly-directed, dorsal spines. By impaling secondary gill lamellae these spines may serve to prevent parasites from being dislodged by gill ventilating currents. Before reaching sexual maturity the parasites leave the secondary gill lamellae and establish themselves in the septal canals. It is uncommon to find more than one adult specimen of Horricauda in each septal canal. The significance of this in relation to sperm exchange is discussed. Like Troglocephalus, Horricauda has eight head sacs, and the suggestion is made that these sacs may play a part in feeding.     

Comparaison entre des Crustacésa Céphalon isolé, a propos d'un beau matériel de syncarides du paléozoïque implications phylogéniques

Are the Eumalacostraca issued from a model of Crustacea which the carapace would have disapeared later on in some of them, and persisted in others, or from one without carapace that some of its decendants would have acquired? In the two instances this ancestor would goes far back, seeing that, already, in the Devonian, Syncarida, Stomatopoda, Phyllocarida and Eocarida were differenciated. With regard to the preliminary survey on a fine material of Syncarida from the Stephanian of the region of Autun, comparisons between two models of Crustaceans from which the cephalon includes only sensorial and gnathal segments, without adjunction of any thoracic metamere, allow to specify the notion of carapace, and to surround the question. The great oldness of the origin of the phyla possessing or not possessing a carapace seems to exclude the hypothesis of a passing over from one model to the other and suggests a representation of the common ancestor which have to be searched in the Cambrian period.     

Ostéologie de Clupavus maroccanus(Crétacé supérieur du Maroc) et considérations sur la position systématique et les relations des Clupavidae au sein de l'ordre des Clupéiformes sensu stricto (Pisces,Teleostei)

Osteology proves definitively that Clupavusmaroccanus is a typical Cluepoid (lateroparietal skull, ethmoidean and fronto-occipital fontanels, recessus lateralis, latero-sagittal fronto-parietal crest, clupeid ural complex, etc…). Clupavus represents a particular non-serrated family, the Clupavidae, different from the Dussumieriidae and the Congothrissidae, the two other primitive non-serrated Clupeoid families. Nor is Clupavus the ancestor of these two families. The systematic position and the relationships of the Clupavidae within the order Clupeiformes sensu stricto are discussed.     

Alkaloid catabolism and mobilization in catharanthus roseus

The catabolic turnover of vindoline and catharanthine, indole-dihydroindole alkaloids produced by Catharanthus roseus, occurs much more rapidly in apical cuttings than in intact plants. The implication of the results is that such alkaloids may participate actively in the plant's biochemical processes under certain conditions, in contradistinction to the general belief that plant alkaloids are metabolically insignificant.