NEUROPEPTIDE Y RECEPTORS FROM CALF BRAIN: EFFECT OF CRUDE CONUS VENOM PREPARATIONS ON [H]NPY BINDING

NPY receptors are identified in calf frontal cortex and hippocampus membrane preparations by binding of N-[propionyl-³H] neuropeptide Y. Saturation and competition binding data with PYY, NPY-(18–36) and NPY itself fit with a single class of sites: for the radioligand K_D = 1.4 ± 0.5 nM, B_max = 434 ± 180 fmol/mg protein in frontal cortex, K_D = 0.7 ± 0.2 nM, B_max = 267 ± 50 fmol/mg protein in hippocampus. Competition curves of the Y₁-subtype selective agonist [Leu³¹, Pro³⁴]NPY are biphasic in both membrane preparations: high affinity sites (i.e. Y₁-subtype) amount to 80% in frontal cortex and 23% in hippocampus. The remaining sites are of the Y₂-subtype. Out of 23 Conus venom preparations, 17 inhibit the binding of [³H]NPY in both membrane preparations, but only two of them (from Conus aulicus and C. pennaceus) do so with high potency (ic₅₀ < 5 μg protein/ml). Only one venom preparation (from C. mercator) had weak discriminatory properties (ic₅₀Y₂/ic₅₀Y₁ = 6). Venom from C. anemone increased the [³H]NPY binding 5-fold and with an ic₅₀ of 15–18 μg protein/ml. This binding occurred to the venom itself and was unrelated to the NPY receptors since it was equally potent when displaced by [Leu³¹, Pro³⁴]NPY, NPY-(18–36), PYY and NPY. Copyright © 1996 Elsevier Science Ltd     

SYNCARID CRUSTACEANS FROM THE MONTCEAU LAGERSTÄTTE (UPPER CARBONIFEROUS; FRANCE)

Abstract: Key aspects of the morphology, autecology, systematics and taphonomy of the crustacean syncarids from the Montceau Lagerstätte (Upper Carboniferous, Stephanian B; France) are presented. Palaeocaris secretanae is the most abundant faunal element of the Montceau biota and shows striking morphological similarities with Palaeocaris typus from the Mazon Creek Lagerstätte (Westphalian D; Illinois, USA). Palaeocaris secretanae was a shrimp‐like animal with a short head (no head shield), large mandibles, 14 trunk segments (the first one being reduced) and a fan‐like caudal termination. Both the body and the appendage design indicate abilities for crawling on the substratum (slender endopods) and for escape reaction (uropodal fan, pleonal flexibility), although swimming activities may have been reduced (trunk appendages with small flap‐like exopods). Details of the appendages involved in feeding, e.g. mandibles and maxillipeds, indicate poor ability for predation but point to an omnivorous detritus feeding mode. Poorly developed respiratory organs (small cylindrical epipods) suggest a relatively low level of locomotory activity. The field of vision may have been large and panoramic (stalked eyes). Rows of pores on 12 trunk segments are interpreted as possible sensory organs used for current detection. Females were brooding eggs (clusters of eggs preserved along anteroventral trunk). Microprobe analysis indicates that siderite is the major component of the nodules. Four events played a key‐role in the three‐dimensional preservation of syncarids: (1) rapid burial, (2) minimal decomposition, (3) phosphatic mineralization shortly after the animal's death and (4) nodule formation around the carcass. Palaeocaris secretanae is morphologically close to Recent syncarids such Anaspides tasmaniae (freshwater streams, Australia) in its general body plan and detailed anatomy, e.g. mouth parts, indicating morphological stasis in syncarids over more than 200 million years.     

Phylogenetic relationships of the lower Caenogastropoda (Mollusca, Gastropoda, Architaenioglossa, Campaniloidea, Cerithioidea) as determined by partial 18s rDNA sequences

Phylogenetic analyses of partial sequences spanning approximately 450 nucleotides near the 5'end of the 18s rDNA strongly support the monophyly of Apogastropoda and its constituent clades, Caenogastropoda and Heterobranchia. Representatives of the architaenioglossan groups Cyclophoroidea, Ampullariidae and Viviparidae invariably emerge within Caenogastropoda in all analyses. While the Cyclophoroidea and Ampullariidae are monophyletic, the varying position of Viviparidae in all outcomes contradicts its hypothesized sister group relationship with Ampullariidae, and thus the monophyly of Ampullarioidea. Because of the position of Viviparidae, Architaenioglossa does not emerge as a clade in any of our analyses. Campanile consistently emerges between Cyclophoroidea and Cerithioidea, or in a clade with Cyclophoroidea and Ampullariidae, a position not predicted by previous morphological studies. Maximum parsimony analyses of sequence data show Caenogastropoda to comprise a series of sequentially diverging higher taxa. However, maximum likelihood analyses as well as maximum parsimony analyses using only trans-versions divide Caenogastropoda into two clades, one containing the architaenioglossan taxa, Campaniloidea and Cerithioidea, the other containing the higher caenogastropod taxa included in Eucaenogastropoda (Haszprunar, 1988) [= Hypsogastropoda (Ponder & Lindberg 1997)l. Denser taxon sampling revealed insertions to be present in the 18s rDNA gene of several caenogastropod taxa. Earlier reports (Harasewych et al. 1997b) of reduced sequence divergence levels in Caenogastropoda are shown to be restricted to Hypsogastropoda. Based on a broader taxonomic sampling, divergence levels within Caenogastropoda are comparable to those found within Heterobranchia.     

CO2-mediated changes in aspen chemistry: effects on gypsy moth performance and susceptibility to virus

We investigated the effects of long-term CO₂ enrichment on foliar chemistry of quaking aspen ( Populus tremuloides ) and the consequences of chemical changes for performance of the gypsy moth ( Lymantria dispar ) and susceptibility of the gypsy moth to a nucleopolyhedrosis virus (NPV). Foliage was collected from outdoor open-top chambers and fed to insects in a quarantine rearing facility. Under enriched CO₂, levels of leaf nitrogen declined marginally, levels of starch and phenolic glycosides did not change, and levels of condensed tannins increased. Long-term bioassays revealed reduced growth (especially females), prolonged development and increased consumption in larvae fed high-CO₂ foliage but no significant differences in final pupal weights or female fecundity. Short-term bioassays showed weaker, and sex-specific, effects of CO₂ treatment on larval performance. Correlation analyses revealed strong, negative associations between insect performance and phenolic glycoside concentrations, independent of CO₂ treatment. Larval susceptibility to NPV did not differ between CO₂ treatments, suggesting that effects of this natural enemy on gypsy moths are buffered from CO₂-induced changes in foliar chemistry. Our results emphasize that the impact of enriched CO₂ on plant–insect interactions will be determined not only by how concentrations of plant compounds are altered, but also by the relevance of particular compounds for insect fitness. This work also underscores the need for studies of genetic variation in plant responses to enriched CO₂ and long-term population-level responses of insects to CO₂-induced changes in host quality.     

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.     

Natural hybridization of two species of tetraploid barbels: Barbus meridionalis and Barbus barbus (Osteichtyes, Cyprinidae) in southern France

Natural hybridization of Barbus barbus and B. meridionalis has been demonstrated in southern France. A genetical study (isozyme electrophoresis) of these species and their hybrids revealed the characteristics of hybridization. Ten enzyme markers and five morphological parameters were used to distinguish between the two parent species. Enzymatic divergence between the parent species included fixed allelic differences at certain loci and reduction in enzymatic activity, including the silencing of certain genes. A morphological study revealed a good correlation between the isozyme markers and morphological characters. Backcrosses were observed and this raises the question of the integrity of the parent species.     

The Diatom Flora of Bethany Boǵ

The results of these studies indicate that the first diatom flora developed at the 13-meter level. The flora at 12 meters increased. At the 11- and 9-meter levels the lake became increasingly eutrophic. Both plankton and benthic forms were present. At the 8- and 7-meter levels the lake was in a transitional stage from lake to bog conditions. From 6 meters to the surface bog conditions were present.     

Molecular Aspects of Fibrin Clot Solubilization

THE human plasma protein, fibrinogen, is a disulphide bonded¹ dimer², each unit containing an Aα, Bβ and 8 chain^*, interconnected by disulphide bridges³. Thrombin (E.C.3.4.4.-13) releases fibrinopeptides A and B from the Aα and Bβ chains respectively⁴ to form fibrin monomer (α₂β₂γ₂) ? which polymerizes to form fibrin polymer or clotted fibrin. This polymer, following factor XIII (plasma transglutaminase, fibrin stabilizing factor) mediated crosslinking among the α chains and among the γ chains⁵, is one of the major and initiating constituents of a thrombus. Fibrinolytic activators, for example, streptokinase (SK) and urokinase (UK), are of thrombolytic value as they convert the thrombus plasminogen to plasmin (E.C.3.4.4.14) which by fibrinolytic action dissolves the thrombus. Whereas the interaction of fibrinogen and plasmin has been well studied^6–9, little is known concerning the mechanism of plasmin mediated fibrin clot lysis. I report here on the mechanism of non-cross-linked fibrin clot solubilization in near physiological conditions.