Systematics of the spider genus Metabus O. P.-Cambridge, 1899 (Araneoidea: Tetragnathidae) with additions to the tetragnathid fauna of Chile and comments on the phylogeny of Tetragnathidae

The spider genus Metabus (Tetragnathidae) previously included nine species: the type M. gravidus O. P.-Cambridge, 1899 – junior synonym of Leucauge ocellata (Keyserling) – from Central America and eight species from Chile. In this paper, the classification of the Metabus species-complex is revised, and two new genera, with three new species and five new combinations, are described. Allende gen. nov. is created for four Chilean species not congeneric with the type of Metabus : the type A. puyehuensis sp. nov. , A. patagiatus (Simon) comb. nov. , A. nigrohumeralis (F. O. P.-Cambridge) comb. nov. and A. longipes (Nicolet) comb. nov. Further additions to the Chilean fauna are under the new genus Mollemeta gen. nov. – created for M. edwardsi (Simon) comb. nov. – and three new species of Chrysometa : C. acinosa sp. nov. , C. levii sp. nov. and C. maitae sp. nov. Metabus now includes four species: M. ocellatus (Keyserling) comb. nov. , M. debilis (O. P.-Cambridge) comb. nov. , M. ebanoverde sp. nov. and M. conacyt sp. nov. All of these species were included in a phylogenetic analysis of 38 tetragnathid and 12 orbicularian outgroup terminals scored for 105 morphological and behavioural characters. The results suggest that Metabus as previously circumscribed is polyphyletic. The phylogenetic relationships within tetragnathids are briefly discussed. © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society , 2007, 151 , 285–335.     

Tradeoffs Between Irradiance Capture and Avoidance in Semi-arid Environments Assessed with a Crown Architecture Model

Plants in arid environments cope with stress from excessiveirradiance by physiological photoprotection of the photosyntheticapparatus and by structurally reducing the leaf area exposedto the sun (structural photoprotection). We assessed the ecologicalrelevance of structural photoprotection in two plants of contrastingarchitecture co-occurring in a semi-arid environment, usingthe three-dimensional canopy model YPLANT. We compared the roleof crown geometry in avoiding excessive radiation, analysedthe costs of structural photoprotection in terms of reductionof potential carbon gain, and compared these costs with thosedue to seasonal constraints of photosynthesis and tissue ageing.The results of the model simulations indicated that canopy architectureofStipa tenacissima(a tussock grass) andRetama sphaerocarpa(aleafless leguminous shrub) minimized the risk of overheatingand photo-oxidative destruction of the photosynthetic apparatuswith steeply oriented foliage and moderate self-shading. Butthis structural photoprotection imposed an increased cost interms of potential carbon gain. Diurnal and seasonal patternsof light interception by the crown of these plants translatedinto a simulated potential carbon gain only half that of anequivalent, horizontal photosynthetic surface. This reductionin potential carbon gain, due to irradiance avoidance, was similarto that imposed by water shortage.S. tenacissima,which ceasesphotosynthetic activity during periods of drought, exhibitedmore structural avoidance of irradiance thanR. sphaerocarpa,whichremains active throughout the year. This illustrates the influenceof the capacity of plants to utilize light for carbon fixationon the trade-offs between irradiance capture and avoidance.Structural avoidance of excessive radiation efficiently preventsthe risk of damage by intense irradiance, has no special maintenancecosts, and is biomechanically cheaper than enhanced light harvestingby a horizontal canopy, which points to structural photoprotectionas a very effective strategy to cope with high irradiance stressin poor and adverse habitats.Copyright 1999 Annals of BotanyCompany Canopy model, functional architecture, irradiance avoidance, light harvesting, photoinhibition, photoprotection, photosynthesis model, plant architecture,Retama sphaerocarpa,semi-arid environment,Stipa tenacissima,structural photoprotection.     

Assimilatory Sulfate Reduction by the Hemoflagellate Leishmania tarentolae1

SYNOPSIS. Continuous growth of one cell line (UCI variant) of Leishmania tarentolae was achieved in the absence of organic sulfur. These cells were able to use sodium sulfate, and, to a limited extent, sodium sulfite as their sole sulfur source and could utilize methionine sulfoxide in place of L-methionine. A related cell line (RU variant) was unable to grow in organic sulfate-free media nor could these cells utilize methionine sulfoxide. UCI promastigotes incorporated significant amounts of ³⁵S sodium sulfate; killed cells did not take up the label. ³⁵S incorporation was inhibited by sodium molybdate (5 × 10^?4 M), sodium arsenite (5 × 10^?4 M), 2,4-dinitrophenol (1 × 10^?4 M), or KCN (5 × 10^?4 M). RU promastigotes did not incorporate significant amounts of ³⁵S sodium sulfate. Thin layer chromatographs of protein hydrolysates from UCI cells incubated in ³⁵S sodium sulfate revealed several radio opaque spots, one of which had chromatographic properties of cystine. UCI variants of L. tarentolae were therefore capable of assimilatory sulfate reduction whereas RU cells lacked this ability.     

Synergism Exerted by 4-Methyl Catechol,Catechol, and Their Respective Quinones on the Rate of DL-DOPA Oxidation by Mushroom Tyrosinase

4-Methyl catechol and catechol, at concentrations ranging from 0.03 to 9 mM and 0.066 to 20 mM, respectively, have a synergistic effect on the rate of DL-DOPA oxidation by mushroom tyrosinase to material absorbing at 475 nm. The synergism results from the ability of 4-methyl catechol-o-quinone (4-methyl-o-benzoquinone) and of catechol-o-quinone (o-benzoquinone) to oxidize DL-DOPA non-enzymatically to dopaquinone, with the latter being immediately converted to dopachrome (λmax = 475 nm).     

Geographic variation of body size and reproductive patterns in Continental versus Mediterranean asp vipers, Vipera aspis

The occurrence of variation in body size and reproductive traits of Vipera aspis was assessed by analysing 74 reproductive females of different populations, collected throughout a large part of the distribution range of the taxon, from central‐western France to central Italy. Six populations were analysed, two of plain habitats, in France and Italy, characterized by a Continental climate, whereas the other four derived from two coastal and two inland, hilly Italian habitats, respectively, showing a Mediterranean climate. Females of the French area showed the smallest mean body size, whereas the pre‐ and post‐partum body masses of females from the coolest, central Italic area were significantly higher. Litter size varied among habitats and was significantly correlated with maternal body size. If the snout–vent length feature varied largely among offspring of different habitats (with the longest size occurring in representatives of the coastal, central Italian area), the average of both body mass and total mass of offsprings did not exhibit any clear pattern among populations colonizing different habitats. Nevertheless, relative litter mass was higher in the French continental populations, and lower in the coolest, Mediterranean, Italian ones. It is worth emphasizing the positive correlation between the snout–vent length feature of females and the total litter mass to environmental factors, such as hottest month temperature and total rainfall. The available literature records that female body size affects offspring size and fecundity. If the present study bolsters this correlation, it also rules out any other effect of female body size on the offspring characteristics analysed. Finally, evidence is provided for the role of climatic factors on life‐history traits (e.g. pre‐partum body mass) of asp vipers, although confounding effects pursued, for example, by food availability may occur. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96 , 383–391.     

Molecular Phylogeny of the Ocelloid-Bearing Dinoflagellates Erythropsidinium and Warnowia (Warnowiaceae, Dinophyceae)

ABSTRACT. Members of the family Warnowiaceae are unarmored phagotrophic dinoflagellates that possess an ocelloid. The genus Erythropsidinium (= Erythropsis ) has also developed a unique dynamic appendage, the piston, which is able to independently retract and extend for at least 2 min after the cell lyses. We provide the first small subunit ribosomal RNA gene sequences of warnowiid dinoflagellates, those of the type Erythropsidinium agile and one species of Warnowia . Phylogenetic analyses show that warnowiid dinoflagellates branch within the Gymnodinium sensu stricto group, forming a cluster separated from the Polykrikos clade and with autotrophic Pheopolykrikos beauchampii as closest relative. This reinforces their classification as unarmored dinoflagellates based on the shape of the apical groove, despite the strong ecological and ultrastructural diversity of the Gymnodinium s.s. group. Other structures, such as the ocelloid and piston, have no systematic value above the genus level.     

Paoay Lake,northern Luzon,the Philippines: a record of Holocene environmental change

The last 7000 years of environmental history for Paoay Lake and its surrounding landscape is examined through the analysis of pollen, diatoms, charcoal, mineral magnetics and AMS dating. Basal sediments contain shells of Cerithiidae and the saline‐tolerant diatom Diploneis indicating that this was an estuarine environment before becoming a freshwater lake after 6000 bp . Pollen analysis shows that submontane forests, characterized by Pinus pollen, underwent a major disturbance around 5000 years ago, recovering to previous levels by 1000 years ago. Charcoal as an indicator of fire is abundant throughout record, although the highest levels occur in the earlier part of the record, between 6500 and 5000 years ago. An aspect of the project was to examine whether there is evidence of land clearance and agricultural development in the region during the late Holocene. While a clear signal of human impact in the record remains equivocal, there appears to be a correspondence between submontane forest decline and mid‐Holocene ocean data that depict warmer and possibly drier conditions for the region. The study highlights the vulnerability of these montane forests to forecasts of a warmer and drier climate in the near future.