First record in America of Aedes albopictus naturally infected with dengue virus during the 1995 outbreak at Reynosa, Mexico

Abstract Mosquito collections were conducted during a dengue outbreak in Reynosa, Tamaulipas, Mexico, July-December 1995. A total of 6694 adult mosquitoes (four genera and nine species) were captured, of which 2986 (78.3% females and 21.7% males) were Aedes albopictus and 2339 (39.7% females and 60.3% males) were Ae.aegypti. These two species comprised 84.2% of the total collection. Specimens were grouped into pools, nearly 50% of them processed for detection of virus by cythopathic effect in C6-36 and VERO cell cultures and by haemagglutination test. Five pools gave positive haemagglutin-ation reactions and were examined by immunofluorescence using monoclonal antibodies to flavivirus and to dengue virus. One pool of ten Ae.albopictus males was positive for dengue virus: serotypes 2 and 3 were identified by serotype-specific monoclonal antibodies arid confirmed by RT-PCR. This is the first report of Ae.albopictus naturally infected with dengue virus in America. Also, it is the very first time Ae.albopictus males have been found infected with dengue virus in the wild.     

Color Term Salience

Eleven focal colors are named by basic color terms in many languages. The most salient colors (black, white, and perhaps red) are named in all languages; the least salient of the set are named in fewer languages. Salience correlates with earliness of introduction, as measured by a scale of social evolution; with brevity of expression, as measured by phonemic length of basic color terms; with frequency of use, as measured by frequency of basic color terms in literary languages; and with frequency of mention in ethnographic literature. None of these correlations are established in the pioneer study of Berlin and Kay (1969), a study whose defects are well exposed by Durbin (1972) and Wescott (1970). The first two were documented respectively in Naroll (1970) and Durbin (1972); the last two are documented here. These four correlations independently support the Berlin-Kay color salience theory. They furnish a sound basis for further research on color term salience in particular and indeed on salience phenomena in general. We speculate that salience may be an important general principle of cultural evolution.     

Postcranial morphology,functional adaptations and palaeobiology of Callistoe vincei,a predaceous metatherian from the Eocene of Salta,north‐western Argentina

Abstract: Callistoe vincei Babot et al., 2002 is a Paleogene borhyaenoid known from exceptionally complete postcranial elements, which provides rare information about the anatomy and evolutionary history of metatherian predators during the South American Cenozoic. The axial skeleton of Callistoe is characterized by the peculiar transverse processes of the cervical vertebrae emphasizing lateral instead of sagittal traction. There is no clavicle and eighteen thoracolumbar vertebrae, of which only five are lumbars. The shoulder and elbow joints suggest movements restricted to parasagittal flexion/extension that are consistent with primarily terrestrial locomotion, as is also emphasized in Borhyaena tuberata and Lycopsis longirostrus. On the manus, the pollex is not reduced and the ungual phalanges indicate very long claws, similar to those observed in some extant digging taxa. This feature is unique to C. vincei among borhyaenoids. The knee joint is characterized by the presence of ossified patellae but shallow femoral trochleae. This joint suggests that the leg was nearly parasagittal, a position also inferred for Borhyaena. The astragalus shape is consistent with parasagittal flexion/extension, as in all Miocene–Pliocene borhyaenoids. The hind foot is characterized by reduced claws in comparison with the manus as well as the slenderness of the first and fifth digits, another peculiarity of C. vincei. The habitat of Callistoe was a temperate humid forest and according to the known fossil record, Callistoe was the largest mammalian predator of its time, sharing the predator ecological niche with crocodiles.     

Effects of Fusicoccin in 'Isolated' Guard Cells of Commelina communis L

The effects of 3 ? 10^–2 mol m^–3 FC on rubidium fluxesand contents in isolated guard cells of Commelina communis L.have been studied using ⁸⁶RbCl. Fusicoccin causes a marked stimulationof influx and an immediate, apparently irreversible, decreasein efflux of ⁸⁶Rb. The effect on influx is usually more importantin determining the new net flux of Rb. Observed fluxes differmarkedly from those predicted by the Goldman-Hodgkin-Katz equation,suggesting that FC does not act solely via an effect upon theplasmalemma potential. Fusicoccin appears to have a more directeffect upon the ion movements associated with changes in stomatalaperture than either ABA or transfer to the dark. Observed changesin Rb content cannot account fully for the osmotic changes associatedwith aperture increase. Key words: Fusicoccin, Guard cells, Ion fluxes, Commelina communis     

Evolution of South American mammalian predators (Borhyaenoidea): anatomical and palaeobiological implications

The evolution of South American carnivorous marsupials, the borhyaenoids, has been investigated through the functional analysis of postcranial adaptive traits and palaeobiological data. There is evidence that the evolutionary history of Borhyaenoidea proceeded from a noncursorial ancestor. The locomotion and habits of the early Palaeocene Mayulestes ferox probably approached a generalized plesiomorphic pattern for marsupial locomotion, i.e. primarily terrestrial with secondary arboreal adaptations. An exceptionally rich early Miocene Patagonian fauna has yielded various morphological predator types, from scansorial ambusher to terrestrial, incipiently cursorial, taxa. The most specialized borhyaenoid was the powerful sabretooth Thylacosmilus atrox that survived until the late Pliocene. The evolution from a scansorial pattern towards a cursorial trend, illustrated by Borhyaena tuberata , and towards the probable development of postlactational parental care in Thylacosmilus , required by its dental specialization and killing strategy, suggests a modification of the selective pressures and predatory activities of the group over evolutionary time.  © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society , 2004, 140 , 487–521.     

Separation and Concentration of Schizonts of Plasmodium falciparum by Percoll Gradients1

A technique for the separation of schizonts of Plasmodium falciparum is described. The different stages of the asexual cell cycle of the parasite were positioned according to their density in a continuous gradient of Percoll. Young trophozoites coincided with erythrocytes in a broad band corresponding to densities from 1.075 to 1.100 g/ml, whereas schizonts were concentrated at a density approximating 1.062 g/ml. The viability of the parasites was unimpaired by this procedure. Young trophozoites and schizonts continued their normal life cycle when cultured after the separation procedure. The percentage of recovery was high, reaching 80% of the initial quantity. Possible applications of the technique are discussed.     

FACTS AND MECHANISMS: A COMPARATIVE SURVEY

1. This review aims to survey the process of translocation of solutes in the phloem, including the experimental observations of the process, hypothetical mechanisms with their consequences, and the compatibility of these mechanisms with the experimental information. 2. Some properties of the sieve elements are summarized. The characteristic constituent of the sieve elements is a fibrillar protein, P-protein, of 60–120 A. filaments, whose function and distribution in intact sieve elements are still the subject of debate. 3. Apart from the very high levels of sucrose (0.3–0.9 m) and of specific amino acids and amides (10–100 mm), the contents of the sieve elements are characterized by close regulation of the ionic content; thus K (20–85 ^mM) and Mg (2.3–23 mM) are very high relative to Na (0.06–0.3 mM) and Ca (0.25–0.5 mM) respectively; the pH is also very high. 4. Convective movement (mass flow) is demanded by the very high rates of mass transfer. The longitudinal sucrose flux is about 2.5 times 10⁶ pmoles cm.^-2 sec.^-1 in petioles, and several times higher in fruits or trees; this is about 10⁵ times any reasonable transmembrane flux, and demands very large loading areas for each file of sieve elements. It also renders unlikely any mechanism demanding an associated trans-membrane flux of any solute which approaches within several orders of magnitude of the sucrose flow. 5. The evidence from tracer measurements (of ¹⁴C or of heat) favour a mass flow of some kind in the sieve tube, with only restricted exchange between the flowing stream and other sucrose pools in the phloem (or out of it). It is not consistent with ready equilibration with a large stationary reservoir of sucrose, or with reverse flows. There is close correspondence between the input and output kinetics of a length of the trans-location path, or of build-up curves at different distances; hence lateral exchange from the moving stream is relatively minor. 6. Tracer measurements show that loading into the translocation stream is relatively slow, and is the main determining factor in the time course of appearance of tracer down the stem, or in the profile of radioactivity against distance in the stem. This applies not only to the initial steep front of radioactivity in the stem, but also to the error function profiles found at longer times in some plants; those do not arise as has been suggested, by exchange in a two-way system of transcellular strands, but are a reflexion of the loading kinetics. 7. The evidence for or against bidirectional movement is equivocal. In conditions in which there is a strong source/sink gradient imposed, the movement of both labelled carbon and heat is consistent with a one-way system, and is difficult to reconcile with two-way movement. However, in the absence of any strong gradient there is evidence for bidirectional movement. It is suggested that the pattern of flow, as well as the direction and rate of flow, may be controlled by the source/sink relations along the path. 8. Electro-osmosis as a mechanism for translocation seems to be ruled out by a number of theoretical difficulties. The most basic of these is the fact that an electro-osmotic mechanism is inherently incapable of the transport of both anions and cations, whereas the phloem can do both. There are further quantitative difficulties. The ratio of sucrose to potassium in the sieve elements is about 10, and if potassium provides the current a longitudinal potassium flux of about 2.5 times 10⁶ pmoles cm.^-2 sec.^-l would therefore be required in petioles, and considerably more in fruits or trees. This raises very great difficulties of potassium circulation to provide a complete current loop, in the path of recirculation, the size of the transmembrane fluxes required, and the energetics of pumping enough potassium to maintain the driving force for electro-osmosis. 9. Possibilities of activated mass flow, by a mechanism similar to that involved in protoplasmic streaming are discussed. Experimental work on streaming in Nitella and in the slime mould Physarum is reviewed, including the evidence that in both these systems, fibrils, made up of 50–70 Å. filaments, are responsible for the production of the motive force, and that these fibrils are akin to actomyosin. 10. Possible ways in which fibrillar P-protein might be organized in the sieve elements to produce translocation are discussed. The force generated by Nitella-type filaments at the density of P-protein in phloem exudate would be more than adequate for the observed rates of flow. Alternatively the fibrillar arrangement in the slime mould is capable of producing volume flows as large as those in phloem. This hypothesis provides a function for P-protein, and is also consistent with the curious ionic concentrations characteristic of sieve elements. 11. It is suggested that the control by the source/sink relations of the pattern, rate and direction of flow in the phloem might be achieved by the orientation of force-generating microfilaments by a Münch-type flow. Such a flow is inevitable if sucrose is pumped in at one end of the path and removed at the other; it seems to be inadequate to explain the rates of mass transfer, but it might be responsible for inducing the correct orientation and polarity in the motive force.     

A peculiar climbing Megalonychidae from the Pleistocene of Peru and its implication for sloth history

The Xenarthra, particularly the Tardigrada, are with the Notoungulata and Marsupialia among the most diversified South American mammals. Lujanian South American Land Mammal Age localities from the coastal Piedra Escrita site and Andean Casa del Diablo Cave, Peru, have yielded three specimens of the Megalonychidae Diabolotherium nordenskioldi gen. nov. This singular fossil sloth exhibits a peculiar mosaic of cranial and postcranial characters. Some are considered convergent with those of other sloths (e.g. 5/4 quadrangular teeth, characteristic of Megatheriidae), whereas others clearly indicate climbing capabilities distinct from the suspensory mode of extant sloths. The arboreal mode of life of D. nordenskioldi is suggested by considerable mobility of the elbow, hip, and ankle joints, a posteriorly convex ulna with an olecranon shorter than in fossorial taxa, a radial notch that faces more anteriorly than in other fossil sloths and forms an obtuse angle with the coronoid process (which increases the range of pronation–supination), a proximodistally compressed scaphoid, and a wide range of digital flexion. D. nordenskioldi underscores the great adaptability of Tardigrada: an arboreally adapted form is now added to the already known terrestrial, subarboreal, and aquatic (marine and freshwater) fossil sloths. A preliminary phylogenetic analysis of the Tardigrada confirmed the monophyly of Megatherioidea, Nothrotheriidae, Megatheriidae, and Megalonychidae, in which Diabolotherium is strongly nested.  © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society , 2007, 149 , 179–235.