Evolutionary and ecological traps for brown bears Ursus arctos in human‐modified landscapes

相似文献   

Detection of exogenous double‐stranded RNA movement in in vitro peanut plants

• New technologies are needed to eliminate mycotoxins and/or fungal pathogens from agricultural products. RNA interference (RNAi) has shown potential to control fungi associated with crops. In RNAi, double‐stranded RNA (dsRNA) targets homologous mRNA for cleavage, and can reach the mRNA of pathogens in contact with the plant. The key element in this process is the movement of RNA signals cell‐to‐cell and over long distances within the plant, and between host plants and parasites.
• In this study, we selected a regulatory gene in the aflatoxin biosynthesis pathway, aflS/aflR, necessary for the production of aflatoxins in Aspergillus spp. We designed a Dicer‐substrate RNA (DsiRNA) to study the movement and stability of the duplex over time in in vitro peanut plants using stem‐loop primers and RT‐PCR for DsiRNA detection.
• The preliminary results demonstrated that DsiRNA was absorbed and moved away from the point of application, spread systemically and was transported rapidly, most likely through the phloem of the shoot, to the sink tissues, such as new auxiliary shoots, flowers and newly formed pegs. The DsiRNA remained detectable for at least 30 days after treatment.
• This is the first time that movement of exogenous DsiRNA in in vitro peanut plants has been described. Since DsiRNA was detectable in the pegs 15 days after treatment, aflatoxin reduction may be possible if the duplexes containing part of the aflatoxin biosynthesis pathogen gene induce silencing in the peanut seeds colonised by Aspergillus spp. The application of small RNAs could be a non‐transformative option for mycotoxin contamination control.

     

Sisyrinchium humahuacense of sect. Segetia a new species from Argentina

Abstract

A new species from the Andean region of northwestern Argentina is described and illustrated: Sisyrinchium humahuacense. This species can be distinguish from its closest related species by three main characters: the presence of a conspicuous horizontal rhizome, the colour of the flowers and the presence of rudimentary leaves not splitting in fibers. A phylogenetic analysis based on DNA sequences supported the inclusion of S. humahuacense within the genus and as part of the section Segetia. Also, a key to species to identify S. humahuacense is presented herein.     

Very low mitochondrial variability in a stingless bee endemic to cerrado

Partamona mulata is a stingless bee species endemic to cerrado, a severely threatened phytogeographical domain. Clearing for pasture without proper soil treatment in the cerrado facilitates the proliferation of termite ground nests, which are the nesting sites for P. mulata. The genetic consequences of these changes in the cerrado environment for bee populations are still understudied. In this work, we analyzed the genetic diversity of 48 colonies of P. mulata collected throughout the species’ distribution range by sequencing two mitochondrial genes, cytochrome oxidase I and cytochrome B. A very low polymorphism rate was observed when compared to another Partamona species from the Atlantic forest. Exclusive haplotypes were observed in two of the five areas sampled. The sharing of two haplotypes between collection sites separated by a distance greater than the flight range of queens indicates an ancient distribution for these haplotypes. The low haplotype and nucleotide diversity observed here suggests that P. mulata is either a young species or one that has been through population bottlenecks. Locally predominant and exclusive haplotypes (H2 and H4) may have been derived from local remnants through cerrado deforestation and the expansion of a few colonies with abundant nesting sites.     

The Identity of Specimens of the Anastrepha fraterculus Complex (Diptera, Tephritidae) with Atypical Aculeus Tip

Several specimens collected in Paraguay along with Anastrepha fraterculus (sensu lato) have an aculeus tip similar to species from the fraterculus complex, but the teeth of the aculeus of these specimens are poorly defined. As Anastrepha species identification is based mostly on subtle differences in the aculeus tip, we studied these specimens with atypical aculeus tips (with poorly defined teeth) that slightly differs from the aculeus tip of species of the fraterculus complex (with well-developed blunt teeth), to determine if this is due to intraspecific variation or if it can characterize a full species. The Paraguayan specimens were separated in six groups under stereomicroscope according to variation in their aculeus tip. Specimens within each group were studied by means of morphometrics (traditional and geometric) and gene sequence analysis (COI and ITS1). Morphometric analyses were significant, but no clear groups were formed by the discriminant analyses of the aculeus and wing, and the COI and ITS1 sequence analysis clustered specimens with all six aculeus variations. Therefore, the subtle morphological differences observed in the aculeus tip of Paraguayan specimens are intraspecific variations and the Paraguayan specimens were more genetically closely related to Anastrepha sp. 3 from the fraterculus complex.     

Permanent Genetic Resources added to Molecular Ecology Resources Database 1 February 2013–31 March 2013

This article documents the addition of 142 microsatellite marker loci to the Molecular Ecology Resources database. Loci were developed for the following species: Agriophyllum squarrosum, Amazilia cyanocephala, Batillaria attramentaria, Fungal strain CTeY1 (Ascomycota), Gadopsis marmoratus, Juniperus phoenicea subsp. turbinata, Liriomyza sativae, Lupinus polyphyllus, Metschnikowia reukaufii, Puccinia striiformis and Xylocopa grisescens. These loci were cross‐tested on the following species: Amazilia beryllina, Amazilia candida, Amazilia rutila, Amazilia tzacatl, Amazilia violiceps, Amazilia yucatanensis, Campylopterus curvipennis, Cynanthus sordidus, Hylocharis leucotis, Juniperus brevifolia, Juniperus cedrus, Juniperus osteosperma, Juniperus oxycedrus, Juniperus thurifera, Liriomyza bryoniae, Liriomyza chinensis, Liriomyza huidobrensis and Liriomyza trifolii.     

Effect of protease mutations on the production of xylanases in Streptomyces lividans

Three protease mutants--7 (tap-), 12 (tap-, ssp-), and 17 (multiple mutations)--of Streptomyces lividans were tested for their influence on protein secretion. Streptomyces lividans grown in xylan secretes 3 xylanases (A, B, and C). Xylanases A (XlnA) and B (XlnB) are secreted by the Sec pathway, whereas xylanase C (XlnC) is secreted by the Tat pathway. The production of XlnA and XlnC was affected in the mutants, suggesting that the mutations interfered with both Sec- and Tat-secretion systems. However, the processing rate for the Sec and Tat precursor was similar to the wild-type strain, indicating that the mutations had no direct effect on secretion. Streptomyces lividans naturally produced 2 forms of XlnB: XlnB1, which contains the catalytic and the xylan-binding domains, and XlnB2, which contains the catalytic domain only. There was no change from the wild-type strain in the ratio of XlnB1/XlnB2 produced by the mutants, indicating that these proteases are not involved in this process. Although XlnA1, partially truncated in its xylan-binding domain, was rapidly degraded to its catalytic domain (XlnA2) in the wild-type strain, the rate of conversion was reduced in the 3 mutants, indicating that the proteases participated to some extent in this proteolytic process.