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31.
The Atlantic Forest is one of the most threatened ecosystems in Brazil, with only 22% of its original coverage remaining. Despite around 900 species of Polistinae being described worldwide and their being widely distributed in the Neotropical region, they are still poorly known in northeastern Brazil, especially in Atlantic Forest. The aim of this work was a survey of social wasps in three fragments of Atlantic Forest with differences in the level of regeneration and in the physiognomy, performed at Michelin Ecological Reserve (located in Igrapiúna, southern Bahia State, Brazil) and employing three methodologies – attractive solution, Malaise trap and light trap ‘Luiz de Queiroz’ – for 12 months in transects. A total of 1066 specimens, belonging to 29 species from nine genera, were collected in the reserve. Epiponini was the richest tribe (23 species) followed by Mischocyttarini (five species) and Polistini (one species). The Malaise trap was not efficient during the night, having a deficit of 5110 hours; the only nocturnal genus, Apoica, was collected with a light trap – an attractive solution that was more efficient. Once it was left for 12 discontinuous days (72 hours), showing that more than one methodology is desirable for wasp surveys. Latitudinal analysis comparing the study area with other areas grouped the Michelin Ecological Reserve with areas in southeastern Brazil, which may be related to a lack of standardization in collecting methods. This study presented the highest richness in this region.  相似文献   
32.
Soft System Dynamics Methodology (SSDM), a systemic methodology product of the combination of two widely used systems-based methodologies from two different systems thinking paradigms, Systems Dynamics (SD) and Soft Systems Methodology (SSM), is presented. The paper argues that by combining some of SD and SSM stages, within the intellectual framework proposed by SSDM, a methodology developed by one of the authors1 much can be gained in a systemic intervention to tackle complex social problematic situations. A framework for comparing the ontological, epistemological and methodological principles of SD, SSM and SSDM is proposed and the synthesizing and dialectical role of SSDM is advanced. The 10 stages of SSDM are outlined and illustrated by an application on a small Peruvian company; and a set of conclusions and points for further research are discussed.  相似文献   
33.
Soccer (football) is identified as the most popular sport in the world with a high turnover of economic-financial resources. The different segments of the soccer (football) value chain exert mutual influence on the variables that rule the dynamics of this sector. In this sense it is necessary to identify the variables that represent the soccer (football) value chain systemically; to understand the interrelationships between these variables, the main difficulties derived from this interrelationship and to point out variables that require actions to increment the results of the soccer (football) value chain as a whole. Hence, this study applied a semi-structured questionnaire with open-ended questions about the problems and leveraging variables that exist in this sports modality. A causal linkage diagram was elaborated based on the answers to the interviews, showing the systemic structure of the soccer (football) value chain in Brazil, whose premise it is to identify the existing circularities and the possibly existing points of leverage. The systemic structure pointed to the economic participation of soccer (football) in the Gross Domestic Product as a central variable to be leveraged, which tends to synthetize the results of the joint action of the actors in this chain. Furthermore, the variables that may limit or amplify the growth were identified. The systemic structure showed that the soccer (football) commodity chain is complex because of the great number of variables and interrelationships needed to represent its dynamics. The relationship between the actors also proved to be a factor of impact on economic and social development.  相似文献   
34.
Brazil has the richest anuran biodiversity in the world and many species have not yet been studied for parasites. One hundred and forty frogs belonging to 18 species (Rhinella schneideri, Dendropsophus aff. minutus, Dendropsophus nanus, Hypsiboas albopunctatus, Hypsiboas punctatus, Hypsiboas raniceps, Phyllomedusa tetraploidea, Pseudis platensis, Scinax fuscovarius, Trachycephalus typhonius, Leptodactylus chaquensis, Leptodactylus fuscus, Leptodactylus aff. latrans, Leptodactylus mystacinus, Leptodactylus podicipinus, Physalaemus cuvieri, Physalaemus nattereri and Elachistocleis bicolor) collected in aquatic habitats in forest remnants and surrounding agricultural landscapes in southern Brazil were examined for endoparasites. Twenty-four species of endoparasites were identified among 21 adult and three larval individuals: one species of Monogenea, Polystoma lopezromani; eight species of Digenea, Catadiscus marinholutzi, Catadiscus propinquus, Choledocystus simulans, Gordoderina sp., Neohaematoloechus neivai, Rauschiella lenti, Rauschiella linguatula, Rauschiella repandum; one species of Cestoda, Ophiotaenia sp.; one species of Acanthocephala, Centrorhyncus sp.; 12 species of Nematoda, Aplectana sp., Aplectana travassosi, Cosmocerca podicipinus, Raillietnema sp., Schrankiana formolusa, Falcaustra mascula, Oxyascaris oxyascaris, Ochoterenella digiticauda, Physaloptera sp., Brevimulticecum sp., Rhabdias sp., Parapharyngodon hylidae; and one species of Annelida, Dero (Allodero) lutzi. The endoparasite fauna found is constituted by generalist species. Two new records of occurrence in Brazil and 33 new host records are reported.  相似文献   
35.
The Atlantic Forest is considered a hotspot biome, one of the most diverse in the world. Currently, due to deforestation, only 22% of the original cover remains, and only 7.5% well preserved. Despite the global importance of this biome, it still lacks basic studies, e.g. primary inventories. Cerambycidae is one of the most diverse groups of beetles, with high ecological and economic importance. The aim of this work was to survey the longhorn beetles (Cerambycidae) in three fragments (Pacangê, Vila 5 and Pancada Grande) of Atlantic Forest within Reserva Ecológica da Michelin (southern Bahia State, Brazil). A total of 166 individuals belonging to 53 species were recorded, 15 of them new geographical records for the state, and one for Brazil. The Shannon index (H) shows Pacangê (H = 2.665) as the most diverse fragment, followed by Pancada Grande (H = 2.658) and Vila 5 (H = 2.565). The most abundant species were Nyssodrysina lignaria (38 specimens collected), followed by Compsibidion vanum (31 specimens). One hundred and ten specimens were captured in Malaise traps, while in light traps only 56 specimens were caught; however, the richness and consequently the diversity in light traps was higher. This is one of the few studies carried out in Atlantic Forest surveying longhorn beetles, and provides primary data on these taxa, to help develop conservation policies for this threatened biome.  相似文献   
36.
Systemic Practice and Action Research - This article presents an approach to the problem that small and medium-sized Mexican lodging enterprises face regarding their ability to adapt to changes in...  相似文献   
37.
The evolution of the amniotic egg was one of the great evolutionary innovations in the history of life, freeing vertebrates from an obligatory connection to water and thus permitting the conquest of terrestrial environments. Among amniotes, genome sequences are available for mammals and birds, but not for non-avian reptiles. Here we report the genome sequence of the North American green anole lizard, Anolis carolinensis. We find that A. carolinensis microchromosomes are highly syntenic with chicken microchromosomes, yet do not exhibit the high GC and low repeat content that are characteristic of avian microchromosomes. Also, A. carolinensis mobile elements are very young and diverse-more so than in any other sequenced amniote genome. The GC content of this lizard genome is also unusual in its homogeneity, unlike the regionally variable GC content found in mammals and birds. We describe and assign sequence to the previously unknown A. carolinensis X chromosome. Comparative gene analysis shows that amniote egg proteins have evolved significantly more rapidly than other proteins. An anole phylogeny resolves basal branches to illuminate the history of their repeated adaptive radiations.  相似文献   
38.
Transcriptome analysis of the acoelomate human parasite Schistosoma mansoni   总被引:1,自引:0,他引:1  
Schistosoma mansoni is the primary causative agent of schistosomiasis, which affects 200 million individuals in 74 countries. We generated 163,000 expressed-sequence tags (ESTs) from normalized cDNA libraries from six selected developmental stages of the parasite, resulting in 31,000 assembled sequences and 92% sampling of an estimated 14,000 gene complement. By analyzing automated Gene Ontology assignments, we provide a detailed view of important S. mansoni biological systems, including characterization of metazoa-specific and eukarya-conserved genes. Phylogenetic analysis suggests an early divergence from other metazoa. The data set provides insights into the molecular mechanisms of tissue organization, development, signaling, sexual dimorphism, host interactions and immune evasion and identifies novel proteins to be investigated as vaccine candidates and potential drug targets.  相似文献   
39.
Recent studies have suggested that bone marrow cells possess a broad differentiation potential, being able to form new liver cells, cardiomyocytes and neurons. Several groups have attributed this apparent plasticity to 'transdifferentiation'. Others, however, have suggested that cell fusion could explain these results. Using a simple method based on Cre/lox recombination to detect cell fusion events, we demonstrate that bone-marrow-derived cells (BMDCs) fuse spontaneously with neural progenitors in vitro. Furthermore, bone marrow transplantation demonstrates that BMDCs fuse in vivo with hepatocytes in liver, Purkinje neurons in the brain and cardiac muscle in the heart, resulting in the formation of multinucleated cells. No evidence of transdifferentiation without fusion was observed in these tissues. These observations provide the first in vivo evidence for cell fusion of BMDCs with neurons and cardiomyocytes, raising the possibility that cell fusion may contribute to the development or maintenance of these key cell types.  相似文献   
40.
Melchor RN  De Valais S  Genise JF 《Nature》2002,417(6892):936-938
The study of fossilized footprints and tracks of dinosaurs and other vertebrates has provided insight into the origin, evolution and extinction of several major groups and their behaviour; it has also been an important complement to their body fossil record. The known history of birds starts in the Late Jurassic epoch (around 150 Myr ago) with the record of Archaeopteryx, whereas the coelurosaurian ancestors of the birds date back to the Early Jurassic. The hind limbs of Late Triassic epoch theropods lack osteological evidence for an avian reversed hallux and also display other functional differences from birds. Previous references to suggested Late Triassic to Early Jurassic bird-like footprints have been reinterpreted as produced by non-avian dinosaurs having a high angle between digits II and IV and in all cases their avian affinities have been challenged. Here we describe well-preserved and abundant footprints with clearly avian characters from a Late Triassic redbed sequence of Argentina, at least 55 Myr before the first known skeletal record of birds. These footprints document the activities, in an environment interpreted as small ponds associated with ephemeral rivers, of an unknown group of Late Triassic theropods having some avian characters.  相似文献   
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