Microfilum Lutjani N. G. N. Sp. (Protozoa Microsporida), A Gill Parasite of the Golden African Snapper Lutjanus Fulgens (Valenciennes, 1830) (Teleost Lutjanidae): Developmental Cycle and Infrastructure

ABSTRACT Microfilum lutjani n. g., n. sp. (Microsporida) was found on the gill filaments of Lutjanus fulgens (Teleost) inhabiting the coasts of Senegal. This microsporidium forms xenomas distinguished by the microvilli covering the plasma membrane. At all stages of development individuals have isolated nuclei and are in direct contact with the host cytoplasm. Merogony is binary and sporogony is tetrasporoblastic. the spore (4.75 times 2.60 μm)) is characterized by a manubrium inserted on a laterally offset anchoring disc and extending into a very short, noncoiled polar filament (no longer than 500 nm) in the form of a hook. This type of polar filament has not been described previously in the Microsporida.     

Ecological distribution and niche segregation of sibling species: the case of bean beetles, Acanthoscelides obtectus Say and A. obvelatus Bridwell

Abstract.  1. Molecular techniques have greatly added to the number of known sympatric cryptic species in insects. Ecological differences between these newly distinguished species are little explored, but niches often appear to overlap strongly. These cases are good models for exploring new ideas about species coexistence and community structure.
2.  Acanthoscelides obtectus and A. obvelatus are two sister species of bean bruchids, which have been confused until the last decade. One important ecological difference between them has emerged, however: A. obtectus is multivoltine and now distributed worldwide, whereas A. obvelatus is univoltine and restricted to Mesoamerica. Where their ranges overlap, the two species share the same host plants and larvae can sometimes complete development in the same seed.
3. The analysis of 27 622 Mexican individuals of the two species in 2001-2002 and 2002-2003 indicates that their niches overlap, but are differentiated with respect to altitude and the kind of beans (wild vs. domesticated). The principal patterns in their relative abundance in different habitats, and at different seasons, were constant from one year to the next.
4. As sympatry of these species seems to be of recent origin, the observed niche differentiation may not have evolved in response to competition, but could instead be the consequence of physiological differences, evolved independently in each species in allopatry, that pre-adapted them for different altitudes and kinds of resources.
5. The combination of biological and historical factors thus appears to allow these two sibling species to coexist in sympatry, despite their broadly overlapping ecological niches.     

A phylogeny for side-necked turtles (Chelonia: Pleurodira) based on mitochondrial and nuclear gene sequence variation

Aspects of the phylogeny of pleurodiran turtles are contentious, particularly within the Chelidae. Morphological analyses group the long-necked Australasian Chelodina and the long-necked South American Chelus and Hydromedusa into a single clade, suggesting a common derived origin of the long neck and associated habits that predated the separation of Australia from South America. In contrast, published analyses of 12SrRNA and cytochrome b sequences suggest that the long-necked Chelodina are more closely related to the short-necked Australasian genera than to either Chelus or Hydromedusa. This paper adds partial sequences of 16S rRNA and CO1 mitochondrial genes and partial sequences of the nuclear oncogene c-mos to test a range of previous hypotheses on the phylogenetic relationships among chelid turtles. In total, 1382 nucleotides were available for each of 25 taxa after elimination of ambiguously aligned regions. These taxa included representatives of all the genera of the turtle families Chelidae and Pelomedusidae, the three sub-genera of Phrynops, and recognized sub-generic groups of Elseya and Chelodina. Of the four genes examined, 12S rRNA was the most informative, followed by c-mos with 16S rRNA and CO1 the least informative. The molecular data support the currently accepted arrangement for pelomedusid genera, that is, a sister relationship between the African Pelusios and Pelomedusa and a clade comprising the South American Peltoceplhalus and Podocnemis with the Madagascan Erymnochelys. However, there is also support for Erymnochelys and Podocnemis as sister taxa to the exclusion of Peltocephalus (bootstrap values of 69–80%) which is at odds with the most commonly accepted arrangement. The South American chelids are monophyletic (76–82%). This clade includes the long-necked Chelus and Hydromedusa, but excludes the Australasian long-necked Chelodina. Furthermore, the South American long-necked chelids are not themselves monophyletic, with 98–100% bootstrap values for the node supporting Chelus and the remaining South American chelids to the exclusion of Hydromedusa. Hence, the hypothesis of a monophyletic grouping of the long-necked genera of South America and Australasia is not supported by the molecular data. Although reciprocal monophyly of the South American and Australasian chelid faunas was the most likely and the most parsimonious arrangement in all but one analysis, bootstrap support for the monophyly of the Australasian chelids was low (52–66%). The South American chelids, Chelodina and the short-necked Australasian chelids form an unresolved trichotomy. The genera Phrynops and Elseya are paraphyletic, leading to a recommendation to elevate the three sub-genera of Phrynops to generic status and support for previous suggestions to erect a new genus for Elseya latistermum and close relatives. A revised classification of the extant Pleurodira is presented, consistent with the phylogenetic relationships that emerge from this study.     

NEW JELLYFISH TAXA FROM THE UPPER JURASSIC LITHOGRAPHIC LIMESTONES OF CERIN (FRANCE): TAPHONOMY AND ECOLOGY

Abstract:  Abundant well-preserved jellyfish impressions are described from the Cerin Lagerstätte (Ain, eastern France). The enclosing sediments are lithographic limestones deposited in a Late Kimmeridgian lagoon lying on an emergent reef complex. Two new taxa of Scyphozoa are proposed: Paraurelia cerinensis gen. et sp. nov. (abundant) and Paraurelia sp. A (rare), and two new taxa of Cubozoa: Bipedalia cerinensis gen. et sp. nov. (rare) and Paracarybdea lithographica gen. et sp. nov. (very rare). Rapid covering by a microbial mat helped the preservation of the animals. Many specimens of Paraurelia cerinensis are deformed by slippage down the palaeoslope, which characterizes the margin of the lagoon. Their resultant morphology and their orientation clearly indicate the downslope direction. Tentacles of Bipedalia cerinensis and Paracarybdea lithographica are also orientated according to the palaeoslope. The jellyfish were probably dead individuals occasionally introduced into the Cerin lagoon. However, another hypothesis may be considered with reference to the model of the present-day jellyfish lakes in Palau (Caroline Islands, Western Pacific). Jellyfish could have lived in the more oxygenated upper layer of water of the Cerin lagoon that allowed pelagic life. This situation could have corresponded to short periods of easier communication between the open sea and the lagoon. Jellyfish are only found in the lower beds of the lithographic limestones and their distribution illustrates the supposed evolution of the Cerin lagoon. Initially, it was deep, mainly flooded, with possibly autochthonous jellyfish and allochthonous animals indicating clear marine influence. Later, the lagoon shallowed and its sediments often emerged with marginal marine burrows and plants indicating increasing terrestrial influence.     

Action du diméthylsulfoxyde sur l'absorption du 42K et du glucose-14C (U) par des disques foliaires de Zea mays et Pelargonium zonale

⁴²K and ¹⁴C (U)-glucose uptake by foliar discs of maize (Zea mays L.) and pelargonium (Pelargonium zonale L.) is inhibited by dimethyl sulfoxide (DMSO) at concentrations of 5 and 10%. This effect increases with the duration of the absorption and appears with varied concentrations in K or glucose. In most cases, this inhibitory effect is less with aged discs than with freshly cut discs. Besides, the DMSO (10%) enhances the exsorption of ⁴²K by foliar discs of maize. The effects of DMSO and two osmotic agents, mannitol and polyethylene glycol 1000, on the uptake and water content of discs are compared. It seems that the effect of DMSO on the uptake is not only an osmotic effect. It may also be related to other actions of this substance in affecting an active uptake.     

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     

Correspondence analysis of shell morphology in the African freshwater snail Biomphalaria pfeifferi (Kraus 1848) (Pulmonata: Gastropoda)

A correspondence analysis of shell measurements taken from 521 widely dispersed specimens of the African aquatic pulmonate snail Biomphalaria pfeifferi suggests the existence of eight morphological groups. These groups appear to relate to either ecophysiological factors or to factors associated with the stability of the freshwater system rather than to aspects of geographic distribution and genetic isolation.