New occurrences of the wood Protocupressinoxylon purbeckensis Francis: implications for terrestrial biomes in southwestern Europe at the Jurassic/Cretaceous boundary

Abstract:  Previously known from the Kimmeridgian–Portlandian of Dorset (UK) only, Protocupressinoxylon purbeckensis wood is reported here from the Kimmeridgian of Asturias (Spain) and Ajoie (Switzerland). The morphospecies taxonomy and nomenclature are discussed, and new supplementary illustrations are given. The P. purbeckensis tree was growing in dry strongly seasonal (tropophilous) environments, and the new occurrences suggest that such a climate prevailed on land all over southwestern Europe at the end of the Jurassic (Kimmeridgian sensu anglico – Portlandian). The review of fossil wood data indicates that such a stressful environment may have constrained terrestrial biocoenoses and their evolution at the Jurassic/Cretaceous boundary. But wood generic diversity curves are also strikingly similar to that drawn 20 years ago for nonmarine tetrapods, implying a fossil Lagerstätte effect.     

Stomatal encryption by epicuticular waxes as a plastic trait modifying gas exchange in a Mediterranean evergreen species (Quercus coccifera L.)

The adaptive benefit of stomatal crypts remains a matter of controversy. This work studies the effect on gas exchange of cuticular rims that overarch the stomatal pore in the Mediterranean species Quercus coccifera L. growing under Mediterranean (lower relative humidities and high summer temperatures) or oceanic conditions (higher daily relative humidities and mild temperatures). After microscopic assessment of the leaf surfaces and stomatal architecture, the impact of the cuticular ‘cup’ on gas exchange was evaluated by employing three‐dimensional finite element models. Here, we provide evidence for a high plasticity of the Q. coccifera cuticular cup, with much larger vents under oceanic conditions compared to small vents under Mediterranean conditions. This structure adds a substantial fixed resistance thereby strongly decreasing gas exchange under Mediterranean conditions. The cuticular cup, which also increases leaf internal humidity, might buffer the rapid changes in vapour pressure deficit (VPD) often observed under Mediterranean conditions. Since water loss of guard and adjacent epidermal cells regulates stomatal aperture, we suggest that this structure allows an efficient regulation of stomatal conductance and optimum use of resources under high VPD. This study provides evidence that plasticity of stomatal architecture can be an important structural component of hydraulic adaptation to different climate conditions.     

Quantitative Growth Relationships of Cassava (Manihot esculenta Crantz): Crop Development in a Savanna Wet Season

Growth characteristics of Manihot esculenta Crantz cv. Cubanawere determined for a crop, cultivated in savanna soil withfive different levels of fertilizer. A population of 25000 plantsha^–1 was studied using conventional growth analysis techniques. The storage root does not act as a sink for large amouns ofassimilates and differences in growth response were mainly aresult of the morphology development and function of leavesin the cassava canopy (source activity). Thus, during tuberization,the cultivar Cubana produces a progressively higher proportionof new leaves, maintaining throughout the season a relativelyhigh net assimilation rate and leaf area index. Manihot esculenta Crantz, Cassava, source-sink relationship, net assimilation rate, leaf area index, growth analysis     

Traditional and New Cable Restraint Systems to Capture Fox in Central Spain

ABSTRACT Capturing animals is an essential tool of wildlife management, but the use of capture devices is being affected by public pressures on an international scale. In Europe, and particularly Spain, foxes (Vulpes vulpes) are often captured using traditional methods such as nonlocking Spanish Snares (SS) set in an ad hoc fence line known as an alar, but these traditional European methods are rarely compared to modernly described restraints such as the Wisconsin Cable Restraint (WR). We evaluated rates of efficiency, selectivity, injury, and impacts to foxes and nontarget species when using SS (as traditionally set in an alar) or WR within alars or on trails in Castilla-La Mancha, Spain. During 40,372 trap-nights from summer to winter of 2007, we captured 64 foxes, and 8 of 23 potential nontarget species. Our results indicated that WR set in trails were more efficient (0.28 capture rate) for capturing red foxes than SS set in an alar (0.11 capture rate). Relative to injury, foxes captured with the WR in the alar (95.4%), and WR in trails (90.5%), and the SS (90.9%) showed no indicators of poor welfare, and injury score analysis indicated that injuries were of similar magnitude for all capture devices. Overall, the WR set in trails may have performed the best, but all 3 methods are likely sufficient for capturing foxes with minimal injury, acceptable efficiency, and acceptable impact to foxes and sympatric nontarget species. Thus, wildlife managers in Spain and elsewhere can apply our findings to optimize capture and management of foxes.     

MICROTUBULES IN THE SHELL OF THE INVASIVE BIVALVE CORBICULA FLUMINEA (MULLER, 1774) (BIVALVIA: HETERODONTA)

Using scanning electron and histological techniques on specimensof the bivalve Corbicula fluminea a new relationship betweenmantle, shell and periostracum has been observed, apparentlyfor the first time. Here we demonstrate that several extensionsof the mantle epithelium pierce the shell to join the innerlayer of the two-layered periostracum. The mantle extensionsare confirmed as unicellular processes. We suggest that theycould serve the animal in the mobilization of calcium from theshell for buffering the extrapalhal fluid under anaerobic conditions,when organic acids accumulate or when an extra contributionof Ca²⁺ is required (Received 5 January 1994; accepted 30 March 1994)     

A Novel Opioid Mechanism Seems to Modulate Phagocytosis in Tetrahymena

ABSTRACT. We have previously reported that a β-endorphin-like substance inhibits phagocytosis in Tetrahymena perhaps by a mu-like opioid receptor. We now report a further characterization of the elements involved in the signal transduction mechanism of this opioid. Affinity chromatography followed by immunoblots of both intracellular extracts and extracellular medium reveal the presence of two main proteins of 64 and 75 kDa. These molecular weights are much higher than that of any known opioid peptide or precursor protein and suggest that we may be dealing with either a novel opioid or with proteins that by chance cross-react with anti-β-endorphin antibody. Nevertheless, when the biological activity of these proteins was tested it was found that they had an effect similar to that of mammalian β-endorphin, namely inhibition of phagocytosis by a naloxone-reversible mechanism. We have probed a size-selected Tetrahymena library with a pro-opiomelanocortin probe and have obtained several positive clones; the sequencing of their inserts should establish whether we are dealing with a bona fide member of the opioid family. Another aspect we have been studying is the G-proteins which appear to be involved in the modulation of phagocytosis. We have found, by means of Western blotting (using an antibody against the conserved GTP-binding region of the α-subunit), two bands of 51 and 59 kDa; no α-subunit of 59 kDa had been reported previously and may represent a novel G-protein. In spite of these differences, the opioid signal transduction mechanism appears to remarkably resemble that present in more complex organisms.     

Transfer of Mass and Energy in a Cassava (Manihot esculenta Crantz cv. Cubana) Community 1. Microclimate and Water Vapour Exchange in a Savanna Climate

The energy balance approach was used to evaluate the transferprocesses which occur between a cassava community, growing duringa savanna wet season, and its environment. Crop performanceunder these conditions was also analysed. During this season, the soil profile remained near saturation,hence net radiation absorbed by the cassava crop during typicallow radiation days, was mainly dissipated as latent heat (78–86per cent); a process which depends on the growth stage and onthe foliage cover of the canopy. However, the seasonal rootenvironment, with a sufficient water supply, contrasted withthe extremely variable shoot environment, because the dailyflux density of short wave radiation input reached values similarto those reported for typical dry season days. On these days,cassava responded to environmental stress mainly by a reductionin transpiration. At the end of the wet season soil water content markedly decreased,an additional stress factor on the roots, which produced a notablereduction of cassava leaf area index. Therefore, the moderatechanges in energy partitioning determined by morphological andphysiological adaptive responses of cassava, produce a hindrancein the equilibrium between water vapour transfer and the surroundingsavanna environment. Manihot esculenta Crantz, cassava, microclimate, energy balance, heat fluxes     

Morphologie et Ultrastructure de Spirochona gemmipara Stein, 1852 (Ciliophora,Chonotrichida). II. Appareil Cytoproctal et Système Excréteur de I'Adulte1

ABSTRACT. Examination of the anterior region of Spirochona gemmipara by combined use of interference contrast microscopy, protargol staining, and transmission electron microscopy has revealed the existence of a cytoproctal apparatus and of an excretory system (contractile vacuole complex), that have often been confused with each other and with the cytopharynx. The cytoproctal apparatus is comprised of an external orifice located at the base of the collar, a cytoproctal canal that is about 20 μm long and delimited by a pellicle with alveoli, and the cytoproct itself. The contractile vauole complex is composed of 6–8 sinuous canals, up to 20 μm long, each of which opens to the exterior by a pore situated among the ciliature of the collar. An ostium, which is the internal orifice of each canal, is connected with a contractile vacuole that is contiguous with a well developed tubular spongiome. Although deeply set, the cytoproct and ostia of S. gemmipara do not appear to be basically different from the corresponding structures described in Paramecium and Tetrahymena.     

A new Patagonian species of Cricosaurus (Crocodyliformes,Thalattosuchia): first evidence of Cricosaurus in Middle–Upper Tithonian lithographic limestone from Gondwana

Abstract:  Upper Jurassic (Tithonian) deposits in north‐western Patagonia, Argentina, have yielded rich and taxonomically diverse assemblages of marine reptiles. These assemblages are also remarkable by their quality of preservation and are represented by ichthyosaurs, plesiosaurs, turtles and crocodyliforms. Despite the abundant crocodyliform record, only two metriorhynchid taxa have been identified: Cricosaurus araucanensis and Dakosaurus andiniensis. Here we described a new species of Cricosaurus, which represents the second species of Cricosaurus in the Tithonian of the Neuquén Basin, and the first metriorhynchid found in lithographic limestone from Gondwana. Furthermore, this specimen has the most complete postcranial remains of any metriorhynchid from South America. The new species is characterized by a short distance between the premaxilla and the nasal, a relatively narrow interorbital width, 23–25 mandibular teeth, bicarinated teeth with fine apicobasally aligned ridges, interalveolar spaces between the first seven teeth approximately 1.5 times longer than the anteroposterior diameter of the respective alveoli. To test the assignment of the new species to Cricosaurus, we carried out two phylogenetic analyses. In both analyses, Cricosaurus lithographicus sp. nov. is nested with other species referred to this genus. This new species has peculiar enamel ornamentation, characterized by numerous, fine apicobasally aligned ridges, when compared to other species of the genus.