260 research outputs found
The Relationship between Collection Strength and Student Achievement
This chapter examines how selected accrediting bodies and academic librarians define collection strength and its relationship to student achievement. Standards adopted by accreditation bodies and library associations, such as the Association of Research Libraries, are reviewed to determine the most common ones which are used to assess library collections. Librarians’ efforts to define and demonstrate the adequacy of library resources are also examined in light of increased focus on institutional accountability, and requirements to provide planned and documented evidence of student success. Also reviewed are the challenges and faced by academic librarians in a shift as they shift from traditional collection-centered philosophies and practices to those which focus on client-centered collection development such as circulation analysis, citation analysis, interlibrary loans and student satisfaction surveys to determine collection use and relevance. The findings from a review of standards and existing library literature indicated that student use of library collections depends on faculty perceptions of the library and whether they require students to use library resources and services for their research papers. Through marketing strategies, improvement of student awareness of collections and library services, the chapter concludes that multiple collection-related factors influence the academic success of students, not just the size and importance of library collections per se. The significance of the chapter lies in its identification of halting and difficult adjustments in measuring both collection “adequacy” and student achievements
A systematic review of the role of regional aviation in the airfreight industry
The purpose of this article is to explore the themes and challenges for regional aviation regarding the provision of airfreight services. The systematic review highlights three major challenges affecting the regional airfreight sector including: integration; infrastructure; and service reliability. There is a considerable dearth of academic literature available in this area. Thus, this paper aims to assist in highlighting these gaps and illustrating the potential for future research opportunities. It is hoped that this work will assist policy-makers, supply chain and air transport industry representatives as they seek to overcome the challenges hindering the development of regional aviation
The regulation of copper stress response genes in the Polychaete Nereis diversicolor during prolonged extreme copper contamination
Polychaetes are frequented in toxicological studies, one reason being that some members occupy shallow burrows in sediments and are maximally exposed to the contaminants that accumulate within them. We have been studying one population of the polychaete Nereis (Hediste) diversicolor exhibiting inheritable tolerance to extreme copper contamination in estuarine sediment. Using transcriptome sequencing data we have identified a suite of genes with putative roles in metal detoxification and tolerance, and measured their regulation. Copper tolerant individuals display significantly different gene expression profiles compared to animals from a nearby population living without remarkable copper levels. Gene transcripts encoding principle copper homeostasis proteins including membrane copper ion transporters, copper ion chaperones and putative metallothionein-like proteins were significantly more abundant in tolerant animals occupying contaminated sediment. In contrast, those encoding antioxidants and cellular repair pathways were unchanged. Nontolerant animals living in contaminated sediment showed no difference in copper homeostasis-related gene expression but did have significantly elevated levels of mRNAs encoding Glutathione Peroxidase enzymes. This study represents the first use of functional genomics to investigate the copper tolerance trait in this species and provides insight into the mechanism used by these individuals to survive and flourish in conditions which are lethal to their conspecifics
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Metal bioaccumulation and cellular fractionation in an epigeic earthworm (Lumbricus rubellus): the interactive influences of population exposure histories, site-specific geochemistry and mitochondrial genotype
Subcellular fractionation techniques were used to describe temporal changes (at intervals from T0 to T70 days) in the Pb, Zn and P partitioning profiles of Lumbricus rubellus populations from one calcareous (MDH) and one acidic (MCS) geographically isolated Pb/Zn-mine sites and one reference site (CPF). MDH and MCS individuals were laboratory maintained on their native field soils; CPF worms were exposed to both MDH and MCS soils. Site-specific differences in metal partitioning were found: notably, the putatively metal-adapted populations, MDH and MCS, preferentially partitioned higher proportions of their accumulated tissue metal burdens into insoluble CaPO4-rich organelles compared with naive counterparts, CPF. Thus, it is plausible that efficient metal immobilization is a phenotypic trait characterising metal tolerant ecotypes. Mitochondrial cytochrome oxidase II (COII) genotyping revealed that the populations indigenous to mine and reference soils belong to distinct genetic lineages, differentiated by 13%, with 7 haplotypes within the reference site lineage but fewer (3 and 4, respectively) in the lineage common to the two mine sites. Collectively, these observations raise the possibility that site-related genotype differences could influence the toxico-availability of metals and, thus, represent a potential confounding variable in field-based eco-toxicological assessments
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Molecular genetic differentiation in earthworms inhabiting a heterogeneous Pb-polluted landscape
A Pb-mine site situated on acidic soil, but comprising of Ca-enriched islands around derelict buildings was used to study the spatial pattern of genetic diversity in Lumbricus rubellus. Two distinct genetic lineages ('A' and 'B'), differentiated at both the mitochondrial (mtDNA COII) and nuclear level (AFLPs) were revealed with a mean inter-lineage mtDNA sequence divergence of approximately 13%, indicative of a cryptic species complex. AFLP analysis indicates that lineage A individuals within one central 'ecological island' site are uniquely clustered, with little genetic overlap with lineage A individuals at the two peripheral sites. FTIR microspectroscopy of Pb-sequestering chloragocytes revealed different phosphate profiles in residents of adjacent acidic and calcareous islands. Bioinformatics found over-representation of Ca pathway genes in ESTPb libraries. Subsequent sequencing of a Ca-transport gene, SERCA, revealed mutations in the protein's cytosolic domain. We recommend the mandatory genotyping of all individuals prior to field-based ecotoxicological assays, particularly those using discriminating genomic technologies
Toxicokinetics of Ag in the terrestrial isopod Porcellionides pruinosus exposed to Ag NPs and AgNO3 via soil and food
Silver nanoparticles (Ag NPs) have been used in numerous consumer products and may enter the soil through the land application of biosolids. However, little is known about the relationship between Ag NP exposure and their bioavailability for soil organisms. This study aims at comparing the uptake and elimination kinetics of Ag upon exposures to different Ag forms (NPs and ionic Ag (as AgNO3)) in the isopod Porcellionides pruinosus. Isopods were exposed to contaminated Lufa 2.2 soil or alder leaves as food. Uptake and elimination rate constants for soil exposure did not significantly differ between Ag NPs and ionic Ag at 30 and 60 mg Ag/kg. For dietary exposure, the uptake rate constant was up to 5 times higher for Ag NPs than for AgNO3, but this was related to feeding activity and exposure concentrations, while no difference in the elimination rate constants was found. When comparing both routes, dietary exposure resulted in lower Ag uptake rate constants but elimination rate constants did not differ. A fast Ag uptake was observed from both routes and most of the Ag taken up seemed not to be eliminated. Synchrotron X-ray fluorescence showed Ag in the S-cells of the hepatopancreas, thus supporting the observations from the kinetic experiment (i.e. low elimination). In addition, our results show that isopods have an extremely high Ag accumulation capacity, suggesting the presence of an efficient Ag storage compartment
Use of DNA barcoding for Brazilian earthworm biodiversity assessment: untangling taxonomy for conservation.
Linking toxicant physiological mode of action with induced gene expression changes in Caenorhabditis elegans
Unique metabolites protect earthworms against plant polyphenols
All higher plants produce polyphenols, for defence against above-ground herbivory. These polyphenols also influence the soil micro- and macro-fauna that break down plant leaf litter. Polyphenols therefore indirectly affect the fluxes of soil nutrients and, ultimately, carbon turnover and ecosystem functioning in soils. It is unknown how earthworms, the major component of animal biomass in many soils, cope with high-polyphenol diets. Here, we show that earthworms possess a class of unique surface-active metabolites in their gut, which we term ‘drilodefensins’. These compounds counteract the inhibitory effects of polyphenols on earthworm gut enzymes, and high-polyphenol diets increase drilodefensin concentrations in both laboratory and field populations. This shows that drilodefensins protect earthworms from the harmful effects of ingested polyphenols. We have identified the key mechanism for adaptation to a dietary challenge in an animal group that has a major role in organic matter recycling in soils worldwide
The DLR Scout Rover during the 2022 Arches Demomission Space on Mount Etna: Operating the Rover outside of its Comfort Zone
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