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Many fishery management tools currently in use have conservation value. They are designed to maintain stocks of commercially important species above target levels. However, their limitations are evident from continuing declines in fish stocks throughout the world. We make the case that to reverse fishery declines, safeguard marine life and sustain ecosystem processes, extensive marine reserves that are off limits to fishing must become part of the management strategy. Marine reserves should be incorporated into modern fishery management because they can achieve many things that conventional tools cannot. Only complete and permanent protection from fishing can protect the most sensitive habitats and vulnerable species. Only reserves will allow the development of natural, extended age structures of target species, maintain their genetic variability and prevent deleterious evolutionary change from the effects of fishing. Species with natural age structures will sustain higher rates of reproduction and will be more resilient to environmental variability. Higher stock levels maintained by reserves will provide insurance against management failure, including risk-prone quota setting, provided the broader conservation role of reserves is firmly established and legislatively protected. Fishery management measures outside protected areas are necessary to complement the protection offered by marine reserves, but cannot substitute for it.  相似文献   
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Sympatry and natural hybridization between howler monkey taxa (Alouatta spp.) has only recently being confirmed in the wild. Surveys in areas of potential contact between the distribution of two taxa have shown that sympatry is rare, although more common than previously known. Here we report the results of a survey conducted in a contact zone between the only two sexually dichromatic howler monkey taxa, Alouatta caraya and A. guariba clamitans, in São Francisco de Assis, State of Rio Grande do Sul, Brazil. Our survey, covering an area of about 400 ha at the Cerro dos Negros (29°33′50″–29°35′10″S, 54°58′40″–54°59′50″W; ~100–279 m a.s.l.), was successful in locating seven black-and-gold and one brown howler monkey social groups living syntopically. Black-and-gold group size ranged from 5 to 15 individuals, whereas the brown group was composed of 7 individuals. The pelage color of three adult males belonging to different black-and-gold groups and another adult male belonging to the brown howler group presented a mosaic of red or rufous and black. These adult males and an adult female living in another black-and-gold group are putative hybrids. Therefore, it appears that pre-zygotic reproductive isolation has not evolved, at least not completely, between these howler monkey species, corroborating previous reports for these and other Alouatta taxa. Future genetic studies need to confirm the occurrence of hybridization in this contact zone, and to determine the viability and fertility of hybrids and their possible offspring. In addition, there is no evidence supporting the existence of significant segregation in habitat and resource utilization by black-and-gold and brown howler monkeys.  相似文献   
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Polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLPs) and sequence analysis of noncoding regions of chloroplast DNA were used to investigate 37 populations of Eritrichium nanum covering its total distribution area, the European Alps. There was no haplotypic variation within the populations, and most haplotypes were restricted to single sites or to neighbouring populations, suggesting low levels of long distance gene flow via seeds. The present geographical distribution of haplotypes probably reflects an ancient geographical pattern within two regions in the intensely glaciated western and eastern central Alps identified as genetic hotspot areas. These two regions contained seven of the total of 11 haplotypes, including many of the most derived ones. The divergent haplotypes formed closely related groups, which supported a separate evolution of these haplotypes in these two regions and, more importantly, gave strong evidence for the in situ survival of these populations on nunataks within the western and eastern central Alps during Pleistocene glaciation. This result is in concordance with a previous study on E. nanum using nuclear markers. Only one haplotype was common and widespread throughout the distributional range of E. nanum. At the same time, it was the evolutionarily basal-most and all other haplotypes were best described as its descendants. This haplotype is hypothesized to be genetically identical to a Tertiary Alpine colonizing ancestor, whose distribution was secondarily fragmented and infiltrated by derived haplotypes originating through local mutations.  相似文献   
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From the aqueous extract of the dry rhizomes of Gunnera perpensa the minor components pyrogallol, succinic acid, lactic acid, and the trimethyl ether of ellagic acid glucoside were isolated. The major constituent was identified as Z-venusol, a phenylpropanoid glucoside. Its structure was verified by X-ray diffraction. Tests on isolated uterine smooth muscle from rats showed that the whole extract stimulated a direct contractile response and induced a state of continuous contractility of the uterus once all additives had been removed from the organ bath. By contrast, venusol did not trigger the direct contractile response but induced the state of continuous contractility once the organ bath was flushed.  相似文献   
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Anopheles aquasalis larvae are salt water tolerant, preferring concentrations between 10 and 20 parts per thousand (ppt). The larvicidal efficacy of two formulations of Bacillus thuringiensis var. israelensis (Vectobac-12AS and Bactivec), was investigated against An. aquasalis at salinities of 0, 10, and 20 ppt. A probit analysis was used to calculate the lethal concentrations (LC50 and LC95) for each product at each salinity. The LC50 and LC95 were higher for Bactivec than Vectobac-12AS, and for Bactivec, the LC50 and LC95 increased with salinity. Vectobac-12AS should thus be preferred to Bactivec for An. aquasalis control, especially in saline breeding habitats.  相似文献   
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Integrated studies that address proteins structure and function in the new era of systems biology and genomics often require the application of high-throughput approaches for parallel production of many different purified proteins from the same organism. Cytochromes c-electron transfer proteins carrying one or more hemes covalently bound to the polypeptide chain-are essential in most organisms. However, they are one of the most recalcitrant classes of proteins with respect to heterologous expression because post-translational incorporation of hemes is required for proper folding and stability. We have addressed this challenge by designing two families of vectors (total of 6 vectors) suitable for ligation-independent cloning and developing a pipeline for expression and solubility analysis of cytochromes c. This system has been validated by expression analysis of thirty genes from Shewanella oneidensis coding for cytochromes c or cytochromes c-type domains predicted to have 1-4 hemes. Out of 30 targets, 26 (87%) were obtained in soluble form in one or more vectors. This work establishes a methodology for high-throughput expression of this class of proteins and provides a clone resource for the microbiological and functional genomics research communities.  相似文献   
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