Reconstructed facial appearance of the sabretoothed felid Smilodon

Life reconstructions are a useful means of providing a package of information about morphology, functionality, behaviour, biology and ecological characteristics of an extinct organism. These reconstructions are of interest not only to researchers but also to a wider public. Reconstructions of sabretoothed cats in particular are widely published and exhibited, despite the absence of a general consensus on either how their canines were used or the prey sought. Cat-like restorations of the American Pleistocene sabretooth genus Smilodon prepared by Charles Knight under the direction of J.C. Merriam were accepted as valid for over three decades until GJ. Miller criticized them, claiming that Smilodon should have looked very different from modern felids. In particular, he argued for a longer mouth opening and lip line to provide a wider gape, a retracted nose and ears set relatively lower on a head with a straighter dorsal profile. These arguments were accepted by many authors employing reconstructions, and have lead to depictions of bizarre appearance and interpretations of rather specialized feeding behaviour. We believe that phylogenetic, anatomical and functional considerations point to substantial flaws in the basis for such depictions, and argue for a return to more felid-like morphology and to interpretations of broadly cat-like eating patterns.     

PCR detection of MLOs in quick decline-affected pear trees in Italy

Polymerase chain reaction (PCR) amplification, using primers derived from the 16S rRNA gene, followed by restriction fragment length polymorphism (RFLP) analysis with Alu I restriction endonuclease was used to detect myc-oplasma-like organisms (MLOs) associated with pear decline. MLOs were consistently detected in pear trees that suddenly wilted and died within a few days during summer, as well as in pears of the same orchards with symptoms similar to the slow form of pear decline. In both cases the same RFLP pattern was obtained. Declining pear trees were 5 to 8-yr-old cvs Williams, Kaiser and Max Red Bartlett grafted on to Pyrus communis seedling rootstocks. All the orchards affected by quick decline had severe attacks of pear psyllid (Cacopsylla pyri) during the year this study was performed and during the previous year. The results showed the suitability of DNA amplification by the polymerase chain reaction for the detection of pear decline MLOs and established that MLOs can be detected in infected tissues of dead trees.     

Effects of canavanine on IAA- and fusicoccin-stimulated cell enlargement, proton extrusion and potassium uptake in maize coleoptiles

In maize coleoptiles (Zea mays F₁ XL 640A, cv. Dekalb) canavanine and cycloheximide strongly and simultaneously inhibit cell elongation, H⁺ extrusion and K⁺ uptake, induced by IAA. They inhibit also, although to a much lesser degree, the same phenomena induced by fusicoccin. Cycloheximide severely depresses the incorporation of leucine into proteins, while canavanine leaves leucine incorporation almost unchanged. The data confirm that elongation, H⁺ extrusion and K⁺ uptake can be regarded as correlated processes; they also support the view that normal protein synthesis is essential for IAA-induced growth, while this requirement is only partial in growth stimulated by fusicoccin.     

Karyotype, DNA Content and Meiotic Behaviour in Five South American Species ofVicia(Fabaceae)

This paper presents the karyotype, DNA content and meiotic behaviourof five species ofViciafrom Argentina (V. macrogramineaBurk.,V.gramineaSM.,V. epetiolarisBurk.,V. pampicolaBurk. andV. nanaVog.).All the species have the same chromosome number and karyotypeformula (2n=14; 6m+4st+4t). Each species, however, displaysa characteristic number and position of the nucleolar organizerregion (NOR) and different sizes of the respective satellites,confirmed by Ag-NOR banding. Moreover, significant differenceswere found in the total chromosome volume (TCV) and DNA contentof the species. Positive correlations between DNA content andTCV, and between DNA content and type of life cycle were alsofound. TCV and DNA content are lower inV. nana(annual) and higherinV. macrograminea(biennial–perennial). The material displayedmarked karyotypic orthoselection, with similar karyotypes inall studied species, even when the overall chromosome size varied.Evolutionary changes in DNA amount are proportional to the relativelength of each chromosome arm, maintaining karyotypic uniformity.Significant differences were found between the meiotic behaviourofV. gramineaand that of the other species.V. gramineahas alower frequency of ring bivalents and chiasmata per cell, andalso has a lower interstitial chiasma frequency. In general,the results are congruent with the morphological data reportedfor these species.Copyright 1998 Annals of Botany Company. Viciaspecies, karyotype, orthoselection, nuclear DNA content, NOR banding, meiotic behaviour.     

FRAMEWORK FOR DEVELOPING PROTOTYPE BIOACOUSTIC DEVICES IN AID OF OPEN SEA KILLER WHALE PROTECTION

ABSTRACT

This paper presents a framework effort to allow the experimentation of various devices in order to automatically record, detect and classify marine mammal vocalizations in the open sea. Some tools for the protection of Killer Whales and other cetaceans are founded in the analysis of their recorded vocalizations. With this framework we are able to test every part under controlled conditions before open sea experiments. Some of these devices have been designed to localize and track open sea populations in order to facilitate data collection for conservation management.

At this moment the framework consists of the basic necessary instruments and IT resources for continuously multichannel recording of vocalizations from four specimens of Killer Whale. The enormous raw data stream forces the implementation of a data reduction strategy. As a result, the present research is focused in the development of techniques for this purpose that will allow the automatic classification of events and obtain statistical data. Complementarily, our research goals are also focused on the design of prototypes for source localization using time tags of events on multiple channels for continuous real time logging of behaviour and position of specimens. This paper presents some preliminary results of automatically detected calls.