998 resultados para Neotropical species
Resumo:
Crown rufolepidotus Caruzo & Riina (Euphorbiaceae s. str.), a new species from Colombia, is here described and illustrated. The new species is endemic to an area of lowland secondary forests in Antioquia. Morphological characters indicate that this species belongs to Croton sect. Cleodora (Klotzsch) Baill. due to its arborescent habit, petiolar glands, 15 to 25 stamens, as well as the pistillate flowers with imbricate sepals and multifid styles.
Resumo:
A systematic revision of the granulatus group of the bothriurid scorpion genus Urophonius Pocock, 1893 is presented. Urophonius pizarroi, n. sp., a new species from central Chile, is described. Urophonius granulatus Pocock, 1898, Urophonius somuncura Acosta, 2003, and Urophonius tregualemuensis Cekalovic, 1981, are redescribed using modern standards. The adult males of U. somuncura and U. tregualemuensis are described for the first time. A distribution map and key to the species of the granulatus group are provided, along with a discussion of their phenology.
Resumo:
Mariner-like elements are widely present in diverse organisms. These elements constitute a large fraction of the eukaryotic genome; they transpose by a ""cut-and-paste"" mechanism with their own transposase protein. We found two groups of mobile elements in the genus Rhynchosciara. PCR using primers designed from R. americana transposons (Ramar1 and Ramar2) were the starting point for this comparative study. Genomic DNA templates of four species: R. hollaenderi, R. millerii, R. baschanti, and Rhynchosciara sp were used and genomic sequences were amplified, sequenced and the molecular structures of the elements characterized as being putative mariner-like elements. The first group included the putative full-length elements. The second group was composed of defective mariner elements that contain a deletion overlapping most of the internal region of the transposase open reading frame. They were named Rmar1 (type 1) and Rmar2 (type 2), respectively. Many conserved amino acid blocks were identified, as well as a specific D,D(34) D signature motif that was defective in some elements. Based on predicted transposase sequences, these elements encode truncated proteins and are phylogenetically very close to mariner-like elements of the mauritiana subfamily. The inverted terminal repeat sequences that flanked the mariner-like elements are responsible for their mobility. These inverted terminal repeat sequences were identified by inverse PCR.
Resumo:
Background: Sigma factors and the alarmone ppGpp control the allocation of RNA polymerase to promoters under stressful conditions. Both ppGpp and the sigma factor sigma(S) (RpoS) are potentially subject to variability across the species Escherichia coli. To find out the extent of strain variation we measured the level of RpoS and ppGpp using 31 E. coli strains from the ECOR collection and one reference K-12 strain. Results: Nine ECORs had highly deleterious mutations in rpoS, 12 had RpoS protein up to 7-fold above that of the reference strain MG1655 and the remainder had comparable or lower levels. Strain variation was also evident in ppGpp accumulation under carbon starvation and spoT mutations were present in several low-ppGpp strains. Three relationships between RpoS and ppGpp levels were found: isolates with zero RpoS but various ppGpp levels, strains where RpoS levels were proportional to ppGpp and a third unexpected class in which RpoS was present but not proportional to ppGpp concentration. High-RpoS and high-ppGpp strains accumulated rpoS mutations under nutrient limitation, providing a source of polymorphisms. Conclusions: The ppGpp and sigma(S) variance means that the expression of genes involved in translation, stress and other traits affected by ppGpp and/or RpoS are likely to be strain-specific and suggest that influential components of regulatory networks are frequently reset by microevolution. Different strains of E. coli have different relationships between ppGpp and RpoS levels and only some exhibit a proportionality between increasing ppGpp and RpoS levels as demonstrated for E. coli K-12.
Resumo:
Measurements in Au + Au collisions at root s(NN) = 200 GeV of jet correlations for a trigger hadron at intermediate transverse momentum (p(T,trig)) with associated mesons or baryons at lower p(T,assoc) indicate strong modification of the away-side jet. The ratio of jet-associated baryons to mesons increases with centrality and p(T,assoc). For the most central collisions, the ratio is similar to that for inclusive measurements. This trend is incompatible with in-vacuum fragmentation but could be due to jetlike contributions from correlated soft partons, which recombine upon hadronization.
Resumo:
We study a stochastic lattice model describing the dynamics of coexistence of two interacting biological species. The model comprehends the local processes of birth, death, and diffusion of individuals of each species and is grounded on interaction of the predator-prey type. The species coexistence can be of two types: With self-sustained coupled time oscillations of population densities and without oscillations. We perform numerical simulations of the model on a square lattice and analyze the temporal behavior of each species by computing the time correlation functions as well as the spectral densities. This analysis provides an appropriate characterization of the different types of coexistence. It is also used to examine linked population cycles in nature and in experiment.
Resumo:
The paired fronto-lateral gland pores and lattice organs (LO1, 2, 3, 4, and 5) of seven species of pedunculate barnacles belonging to two thoracican suborders, Heteralepadomorpha (family Heteralepadidae: Heteralepas sp. 1 and 2) and Lepadomorpha (families Poecilasmatidae: Poecilasma inaequilaterale and Octolasmis aymonini geryonophila and Lepadidae: Lepas pacifica, Dosima fascicularis, and Conchoderma virgatum), were investigated by scanning electron microscopy (SEM). While the fronto-lateral gland pores exhibit slight variation among species, with only L. pacifica showing a different morphology, the variations in the arrangement of LOs are phylogenetically instructive. The lattice organs in the foregoing species correspond in general to the inferred advanced type (Type C), but the distinct keel in the pore field in P. inaequilaterale and L. pacifica is reminiscent of, but not necessarily identical with the less advanced Type B. The arrangement of the anterior LOs (1-2) is rhomboidal in the two heteralepadomorph species, the two poecilasmatid species, and two of the three lepadid species, as it is in all previously and presently known lepadomorph cyprids except D. fascicularis. In this last species, they are deployed linearly along the hinge line. A linear arrangement of all the lattice organs is presumably the plesiomorphic condition for the Thoracica; an obvious exception being the pattern seen in Ibla cumingi. The arrangement of the first two pairs of posterior LOs (3-4) in O. a. geryonophila and C. virgatum differs from that of all previously described Lepadomorpha in being rhomboidal rather than aligned linearly along the hinge line. This same arrangement of LOs 3 and 4 in the two heteralepadomorph species is notable since it is not known in other thoracicans. Our results concerning variation in lattice organs of the lower Pedunculata are more or less consistent with current phylogenetic speculations and genetic information that ally Heteralepadomorpha with Lepadomorpha. Significance of this variation at lower taxonomic levels is also evident in the two similar forms of Heteralepas.
Resumo:
This study investigated the composition and antifungal activity against Cladosporium sphaerospermum and Cladosporium cladosporioides of essential oils of leaves of Piper cernuum, Piper diospyrifolium, Piper crassinervium, Piper solmsianum and Piper umbelata and fruits of P. cernuum and P. diospyrifolium. The essentials oils were analyzed by GC-MS and submitted of the antifungal activity tests. The essential oils of fruits from P. cernuum and leaves of P. crassinervium and P. solmsianum showed potential antifungal activity against C. sphaerospermum and C. cladosporioides. In addition, this is the first report of the composition of essential oils of fruits of P. cernuum and P. diospyrifolium.