Open Access. Powered by Scholars. Published by Universities.®

Genetics and Genomics Commons

Open Access. Powered by Scholars. Published by Universities.®

9,431 Full-Text Articles 26,556 Authors 1,190,127 Downloads 233 Institutions

All Articles in Genetics and Genomics

Faceted Search

9,431 full-text articles. Page 1 of 330.

Work-Type Influences Perceived Livestock Herding Success In Australian Working Kelpies, Jonathan B. Early, Elizabeth R. Arnott, Lisa J. Mascord, Diane van Rooy, Paul McGreevy, Claire M. Wade 2019 University of Sydney

Work-Type Influences Perceived Livestock Herding Success In Australian Working Kelpies, Jonathan B. Early, Elizabeth R. Arnott, Lisa J. Mascord, Diane Van Rooy, Paul Mcgreevy, Claire M. Wade

Paul McGreevy, Ph.D.

Background

Working dog handlers and breeders have very different behavioural requirements in the animals that they employ for managing livestock. The Australian Working Kelpie breed may be used in several working contexts, notably yards, paddocks and a combination of both. The working context influences the skillsets required and gives rise to three corresponding work-types: Yard, Paddock and Utility Kelpies. In particular, dogs used for working stock in the confines of yards and trucks interact with stock more forcefully than those mustering in larger areas (paddocks) where they can herd stock effectively from a greater distance. This article explores owner assessments ...


Gene Expression Programs During Shoot, Root, And Callus Development In Arabidopsis Tissue Culture, Ping Che, Sonia Lall, Dan Nettleton, Stephen H. Howell 2019 Iowa State University

Gene Expression Programs During Shoot, Root, And Callus Development In Arabidopsis Tissue Culture, Ping Che, Sonia Lall, Dan Nettleton, Stephen H. Howell

Dan Nettleton

Shoots can be regenerated from Arabidopsis (Arabidopsis thaliana) root explants in tissue culture through a two-step process requiring preincubation on an auxin-rich callus induction medium. Regenerating tissues can be directed along different developmental pathways leading to the formation of shoots, new roots, or callus by transferring to the appropriate organ induction medium. Using gene-profiling methods, we identified groups of genes that serve as molecular signatures of the different developmental processes, i.e. genes that were specifically up- or down-regulated on one developmental pathway, but not on others. One transcription factor gene that was up-regulated during early shoot development was RAP2 ...


Transcript-Based Cloning Of Rrp46, A Regulator Of Rrna Processing And R Gene–Independent Cell Death In Barley–Powdery Mildew Interactions, Liu Xi, Matthew J. Moscou, Yan Meng, Weihui Xu, Rico A. Caldo, Miranda Shaver, Dan Nettleton, Roger P. Wise 2019 Iowa State University

Transcript-Based Cloning Of Rrp46, A Regulator Of Rrna Processing And R Gene–Independent Cell Death In Barley–Powdery Mildew Interactions, Liu Xi, Matthew J. Moscou, Yan Meng, Weihui Xu, Rico A. Caldo, Miranda Shaver, Dan Nettleton, Roger P. Wise

Dan Nettleton

Programmed cell death (PCD) plays a pivotal role in plant development and defense. To investigate the interaction between PCD and R gene–mediated defense, we used the 22K Barley1 GeneChip to compare and contrast time-course expression profiles of Blumeria graminis f. sp hordei (Bgh) challenged barley (Hordeum vulgare) cultivar C.I. 16151 (harboring the Mla6 powdery mildew resistance allele) and its fast neutron–derived Bgh-induced tip cell death1 mutant, bcd1. Mixed linear model analysis identified genes associated with the cell death phenotype as opposed to Rgene–mediated resistance. One-hundred fifty genes were found at the threshold P value < 0.0001 and a false discovery rate bcd1mutant. Gene Ontology and rice (Oryza ...


Hierarchical Modeling And Differential Expression Analysis For Rna-Seq Experiments With Inbred And Hybrid Genotypes, Andrew Lithio, Dan Nettleton 2019 Iowa State University

Hierarchical Modeling And Differential Expression Analysis For Rna-Seq Experiments With Inbred And Hybrid Genotypes, Andrew Lithio, Dan Nettleton

Dan Nettleton

The performance of inbred and hybrid genotypes is of interest in plant breeding and genetics. High-throughput sequencing of RNA (RNA-seq) has proven to be a useful tool in the study of the molecular genetic responses of inbreds and hybrids to environmental stresses. Commonly used experimental designs and sequencing methods lead to complex data structures that require careful attention in data analysis. We demonstrate an analysis of RNA-seq data from a split-plot design involving drought stress applied to two inbred genotypes and two hybrids formed by crosses between the inbreds. Our generalized linear modeling strategy incorporates random effects for whole-plot experimental ...


Toward Mass Spectrometry Imaging In The Metabolomics Scale: Increasing Metabolic Coverage Through Multiple On-Tissue Chemical Modifications, Maria Emilia Dueñas, Evan A. Larson, Young Jin Lee 2019 Iowa State University

Toward Mass Spectrometry Imaging In The Metabolomics Scale: Increasing Metabolic Coverage Through Multiple On-Tissue Chemical Modifications, Maria Emilia Dueñas, Evan A. Larson, Young Jin Lee

Young-Jin Lee

Exploring the metabolic differences directly on tissues is essential for the comprehensive understanding of how multicellular organisms function. Mass spectrometry imaging (MSI) is an attractive technique toward this goal; however, MSI in metabolomics scale has been hindered by multiple limitations. This is most notable for single cell level high-spatial resolution imaging because of the limited number of molecules in small sampling size and the low ionization yields of many metabolites. Several on-tissue chemical derivatization approaches have been reported to increase MSI signals of targeted compounds, especially in matrix-assisted laser desorption/ionization (MALDI)- MSI. Herein, we adopt a combination of chemical ...


Toward Mass Spectrometry Imaging In The Metabolomics Scale: Increasing Metabolic Coverage Through Multiple On-Tissue Chemical Modifications, Maria Emilia Dueñas, Evan A. Larson, Young Jin Lee 2019 Iowa State University

Toward Mass Spectrometry Imaging In The Metabolomics Scale: Increasing Metabolic Coverage Through Multiple On-Tissue Chemical Modifications, Maria Emilia Dueñas, Evan A. Larson, Young Jin Lee

Chemistry Publications

Exploring the metabolic differences directly on tissues is essential for the comprehensive understanding of how multicellular organisms function. Mass spectrometry imaging (MSI) is an attractive technique toward this goal; however, MSI in metabolomics scale has been hindered by multiple limitations. This is most notable for single cell level high-spatial resolution imaging because of the limited number of molecules in small sampling size and the low ionization yields of many metabolites. Several on-tissue chemical derivatization approaches have been reported to increase MSI signals of targeted compounds, especially in matrix-assisted laser desorption/ionization (MALDI)- MSI. Herein, we adopt a combination of chemical ...


Accelerated Accumulation Of Retinal Α-Synuclein (Pser129) And Tau, Neuroinflammation, And Autophagic Dysregulation In A Seeded Mouse Model Of Parkinson's Disease, Najiba Mammadova, Corey M. Summers, Robyn D. Kokemuller, Qing He, Shaowei Ding, Thierry Baron, Chenxu Yu, Rudy J. Valentine, Donald S. Sakaguchi, Anumantha G. Kanthasamy, Justin J. Greenlee, M. Heather West Greenlee 2019 Iowa State University

Accelerated Accumulation Of Retinal Α-Synuclein (Pser129) And Tau, Neuroinflammation, And Autophagic Dysregulation In A Seeded Mouse Model Of Parkinson's Disease, Najiba Mammadova, Corey M. Summers, Robyn D. Kokemuller, Qing He, Shaowei Ding, Thierry Baron, Chenxu Yu, Rudy J. Valentine, Donald S. Sakaguchi, Anumantha G. Kanthasamy, Justin J. Greenlee, M. Heather West Greenlee

Chenxu Yu

Parkinson's disease (PD) is a neurodegenerative disorder characterized by accumulation of misfolded α-synuclein within the central nervous system (CNS). Visual problems in PD patients are common, although retinal pathology associated with PD is not well understood. The purpose of this study was to investigate retinal pathology in a transgenic mouse model (TgM83) expressing the human A53T α-synuclein mutation and assess the effect of α-synuclein “seeding” on the development of retinal pathology. Two-month-old TgM83 mice were intracerebrally inoculated with brain homogenate from old (12–18 months) TgM83 mice. Retinas were then analyzed at 5 months of age. We analyzed retinas ...


Root Type-Specific Reprogramming Of Maize Pericycle Transcriptomes By Local High Nitrate Results In Disparate Lateral Root Branching Patterns, Peng Yu, Jutta A. Baldauf, Andrew Lithio, Caroline Marcon, Dan Nettleton, Chunjian Li, Frank Hochholdinger 2019 China Agricultural University

Root Type-Specific Reprogramming Of Maize Pericycle Transcriptomes By Local High Nitrate Results In Disparate Lateral Root Branching Patterns, Peng Yu, Jutta A. Baldauf, Andrew Lithio, Caroline Marcon, Dan Nettleton, Chunjian Li, Frank Hochholdinger

Dan Nettleton

The adaptability of root system architecture to unevenly distributed mineral nutrients in soil is a key determinant of plant performance. The molecular mechanisms underlying nitrate dependent plasticity of lateral root branching across the different root types of maize are only poorly understood. In this study, detailed morphological and anatomical analyses together with cell type-specific transcriptome profiling experiments combining laser capture microdissection with RNA-seq were performed to unravel the molecular signatures of lateral root formation in primary, seminal, crown, and brace roots of maize (Zea mays) upon local high nitrate stimulation. The four maize root types displayed divergent branching patterns of ...


Genomic Neighborhoods For Arabidopsisretrotransposons: A Role For Targeted Integration In The Distribution Of The Metaviridae, Brooke D. Peterson-Burch, Dan Nettleton, Daniel F. Voytas 2019 U.S. Department of Agriculture

Genomic Neighborhoods For Arabidopsisretrotransposons: A Role For Targeted Integration In The Distribution Of The Metaviridae, Brooke D. Peterson-Burch, Dan Nettleton, Daniel F. Voytas

Dan Nettleton

Background: Retrotransposons are an abundant component of eukaryotic genomes. The high quality of the Arabidopsis thaliana genome sequence makes it possible to comprehensively characterize retroelement populations and explore factors that contribute to their genomic distribution.

Results: We identified the full complement of A. thaliana long terminal repeat (LTR) retroelements using RetroMap, a software tool that iteratively searches genome sequences for reverse transcriptases and then defines retroelement insertions. Relative ages of full-length elements were estimated by assessing sequence divergence between LTRs: the Pseudoviridae were significantly younger than the Metaviridae. All retroelement insertions were mapped onto the genome sequence and their distribution ...


Co-Expression Networks Reveal Potential Regulatory Roles Of Mirnas In Fatty Acid Composition Of Nelore Cattle, Priscila S. N. de Oliveira, Luiz L. Coutinho, Aline S. M. Cesar, Wellison J. da Silva Diniz, Marcela M. de Souza, Bruno G. Andrade, James E. Koltes, Gerson B. Mourão, Adhemar Zerlotini, James M. Reecy, Luciana C. A. Regitano 2019 Embrapa Pecuária Sudeste

Co-Expression Networks Reveal Potential Regulatory Roles Of Mirnas In Fatty Acid Composition Of Nelore Cattle, Priscila S. N. De Oliveira, Luiz L. Coutinho, Aline S. M. Cesar, Wellison J. Da Silva Diniz, Marcela M. De Souza, Bruno G. Andrade, James E. Koltes, Gerson B. Mourão, Adhemar Zerlotini, James M. Reecy, Luciana C. A. Regitano

Animal Science Publications

Fatty acid (FA) content affects the sensorial and nutritional value of meat and plays a significant role in biological processes such as adipogenesis and immune response. It is well known that, in beef, the main FAs associated with these biological processes are oleic acid (C18:1 cis9, OA) and conjugated linoleic acid (CLA-c9t11), which may have beneficial effects on metabolic diseases such as type 2 diabetes and obesity. Here, we performed differential expression and co-expression analyses, weighted gene co-expression network analysis (WGCNA) and partial correlation with information theory (PCIT), to uncover the complex interactions between miRNAs and mRNAs expressed in ...


The Development And Use Of Computational Tools In Forensic Science, Dennis E. Slice 2019 Florida State University, Tallahassee, USA; University of Vienna, Vienna, Austria

The Development And Use Of Computational Tools In Forensic Science, Dennis E. Slice

Human Biology Open Access Pre-Prints

Modern computational resources make available a rich toolkit of statistical methods that can be applied to forensic questions. This toolkit is built on the foundation of statistical developments dating back to the 19th century. To fully and effectively exploit these developments, both the makers and users of software must be keenly aware of the quality, i.e., the accuracy and precision, of the data being modeled or analyzed, and end-users must be sufficiently familiar with the underlying theory to understand the process and results of any analysis or software they use. This is especially important for medico-legal personnel who might ...


Probability, Populations, Phylogenetics And Hominin Speciation, Niccolo Caldararo 2019 San Francisco State University

Probability, Populations, Phylogenetics And Hominin Speciation, Niccolo Caldararo

Human Biology Open Access Pre-Prints

A number of recent articles have appeared on the hominin Denisova fossil remains. Many of them focus on attempts to produce DNA sequences from the extracted samples. Often these project mtDNA sequences from the fossil remains of a number of Neandertal fossils and the Denisovans in an attempt to understand the evolution of Mid Pleistocene human ancestors. These papers, introduce a number of problems in the interpretation of speciation in hominins. One concerns the degradation of the ancient DNA and its interpretation as authentic genetic information. Another concerns the idea of “species” versus that of “population” and the use of ...


Ontogeny Of The Maize Shoot Apical Meristem, Elizabeth M. Takacs, Jie Li, Chuanlong Du, Lalit Ponnala, Diane Janick-Buckner, Jianming Yu, Gary J. Muehlbauer, Patrick S. Schnable, Marja C. P. Timmermans, Qi Sun, Dan Nettleton, Michael J. Scanlon 2019 Cornell University

Ontogeny Of The Maize Shoot Apical Meristem, Elizabeth M. Takacs, Jie Li, Chuanlong Du, Lalit Ponnala, Diane Janick-Buckner, Jianming Yu, Gary J. Muehlbauer, Patrick S. Schnable, Marja C. P. Timmermans, Qi Sun, Dan Nettleton, Michael J. Scanlon

Dan Nettleton

The maize (Zea mays) shoot apical meristem (SAM) arises early in embryogenesis and functions during stem cell maintenance and organogenesis to generate all the aboveground organs of the plant. Despite its integral role in maize shoot development, little is known about the molecular mechanisms of SAM initiation. Laser microdissection of apical domains from developing maize embryos and seedlings was combined with RNA sequencing for transcriptomic analyses of SAMontogeny. Molecular markers of key events during maize embryogenesis are described, and comprehensive transcriptional data from six stages in maize shoot development are generated. Transcriptomic profiling before and after SAM initiation indicates ...


Nonsyntenic Genes Drive Highly Dynamic Complementation Of Gene Expression In Maize Hybrids, Anja Paschold, Nick B. Larson, Caroline Marcon, James C. Schnable, Cheng-Ting Yeh, Christa Lanz, Dan Nettleton, Hans-Peter Piepho, Patrick S. Schnable, Frank Hochholdinger 2019 University of Bonn

Nonsyntenic Genes Drive Highly Dynamic Complementation Of Gene Expression In Maize Hybrids, Anja Paschold, Nick B. Larson, Caroline Marcon, James C. Schnable, Cheng-Ting Yeh, Christa Lanz, Dan Nettleton, Hans-Peter Piepho, Patrick S. Schnable, Frank Hochholdinger

Dan Nettleton

Maize (Zea mays) displays an exceptional level of structural genomic diversity, which is likely unique among higher eukaryotes. In this study, we surveyed how the genetic divergence of two maize inbred lines affects the transcriptomic landscape in four different primary root tissues of their F1-hybrid progeny. An extreme instance of complementation was frequently observed: genes that were expressed in only one parent but in both reciprocal hybrids. This single-parent expression (SPE) pattern was detected for 2341 genes with up to 1287 SPE patterns per tissue. As a consequence, the number of active genes in hybrids exceeded that of their parents ...


Analysis Of The Genetic Architecture Of Maize Kernel Size Traits By Combined Linkage And Association Mapping, Min Liu, Xiaolong Tan, Yan Yang, Peng Liu, Xiaoxiang Zhang, Yinchao Zhang, Lei Wang, Yu Hu, Langlang Ma, Zhaoling Li, Yanling Zhang, Chaoying Zou, Haijian Lin, Shibin Gao, Michael Lee, Thomas Lubberstedt, Guangtang Pan, Yaou Shen 2019 Sichuan Agricultural University

Analysis Of The Genetic Architecture Of Maize Kernel Size Traits By Combined Linkage And Association Mapping, Min Liu, Xiaolong Tan, Yan Yang, Peng Liu, Xiaoxiang Zhang, Yinchao Zhang, Lei Wang, Yu Hu, Langlang Ma, Zhaoling Li, Yanling Zhang, Chaoying Zou, Haijian Lin, Shibin Gao, Michael Lee, Thomas Lubberstedt, Guangtang Pan, Yaou Shen

Thomas Lubberstedt

Kernel size‐related traits are the most direct traits correlating with grain yield. The genetic basis of three kernel traits of maize, kernel length (KL), kernel width (KW) and kernel thickness (KT), was investigated in an association panel and a biparental population. A total of 21 single nucleotide polymorphisms (SNPs) were detected to be most significantly (P < 2.25 × 10−6) associated with these three traits in the association panel under four environments. Furthermore, 50 quantitative trait loci (QTL) controlling these traits were detected in seven environments in the intermated B73 × Mo17 (IBM) Syn10 doubled haploid (DH) population, of which eight were repetitively identified in at least three environments. Combining the two mapping populations revealed that 56 SNPs (P < 1 × 10−3) fell within 18 of the QTL confidence intervals. According to the top significant SNPs, stable‐effect SNPs and the co‐localized SNPs by association analysis and linkage mapping, a total of 73 candidate genes were identified, regulating seed development. Additionally, seven miRNAs were found to situate within the linkage disequilibrium (LD) regions of the co‐localized SNPs, of which zma‐miR164e was demonstrated to cleave the mRNAs of Arabidopsis CUC1, CUC2 and NAC6 in vitro. Overexpression of zma‐miR164e resulted in the down‐regulation of these genes above and the failure of seed formation in Arabidopsis pods, with the increased branch number. These findings provide insights into the mechanism of ...


Gene Expression Profiling In Salmonella Choleraesuis-Infected Porcine Lung Using A Long Oligonucleotide Microarray, Shu-Hong Zhao, Daniel Kuhar, Joan K. Lunney, Harry Dawson, Catherine Guidry, Jolita J. Uthe, Shawn M. D. Bearson, Justin Recknor, Dan Nettleton, Christopher K. Tuggle 2019 Iowa State University

Gene Expression Profiling In Salmonella Choleraesuis-Infected Porcine Lung Using A Long Oligonucleotide Microarray, Shu-Hong Zhao, Daniel Kuhar, Joan K. Lunney, Harry Dawson, Catherine Guidry, Jolita J. Uthe, Shawn M. D. Bearson, Justin Recknor, Dan Nettleton, Christopher K. Tuggle

Dan Nettleton

Understanding the transcriptional response to pathogenic bacterial infection within food animals is of fundamental and applied interest. To determine the transcriptional response to Salmonella enterica serovar Choleraesuis (SC) infection, a 13,297-oligonucleotide swine array was used to analyze RNA from control, 24-h postinoculation (hpi), and 48-hpi porcine lung tissue from pigs infected with SC. In total, 57 genes showed differential expression (p < 0.001; false discovery rate = 12%). Quantitative real-time PCR (qRT-PCR) of 61 genes was used to confirm the microarray results and to identify pathways responding to infection. Of the 33 genes identified by microarray analysis as differentially expressed, 23 were confirmed by qRT-PCR results. A novel finding was that two transglutaminase family genes (TGM1 and TGM3) showed dramatic increases in expression postinoculation; combined with several other apoptotic genes, they indicated the induction of apoptotic pathways during SC infection. A predominant T helper 1-type immune response occurred during infection, with interferon γ ...


Mechanistic Basis For Control Of Early Embryonic Development By A 5’ Trna Fragment, Xin Y. Bing 2019 University of Massachusetts Medical School

Mechanistic Basis For Control Of Early Embryonic Development By A 5’ Trna Fragment, Xin Y. Bing

GSBS Dissertations and Theses

Ancestral environmental conditions can instruct offspring development, although the mechanism(s) underlying such transgenerational epigenetic inheritance is unclear. In murine models focused on paternal dietary effects, we and others have identified tRNA fragments (tRFs) in mature sperm as potential carriers of epigenetic information. In our search for molecular targets of specific tRFs, we observed that altering the level of 5’-tRF Glycine-GCC (tRF-GG) in mouse embryonic stem cells (mESCs) and preimplantation embryos modulates the expression of the endogenous retrovirus MERV-L and genes regulated by MERV-L. Intriguingly, transient derepression of MERV-L is associated with totipotency of two-cell stage embryos and a ...


Laser Microdissection Of Narrow Sheath Mutant Maize Uncovers Novel Gene Expression In The Shoot Apical Meristem, Xiaolan Zhang, Shahinez Madi, Lisa Borsuk, Dan Nettleton, Robert J. Elshire, Brent Buckner, Diane Janick-Buckner, Jon Beck, Marja Timmermans, Patrick S. Schnable, Michael J. Scanlon 2019 University of Georgia

Laser Microdissection Of Narrow Sheath Mutant Maize Uncovers Novel Gene Expression In The Shoot Apical Meristem, Xiaolan Zhang, Shahinez Madi, Lisa Borsuk, Dan Nettleton, Robert J. Elshire, Brent Buckner, Diane Janick-Buckner, Jon Beck, Marja Timmermans, Patrick S. Schnable, Michael J. Scanlon

Dan Nettleton

Microarrays enable comparative analyses of gene expression on a genomic scale, however these experiments frequently identify an abundance of differentially expressed genes such that it may be difficult to identify discrete functional networks that are hidden within large microarray datasets. Microarray analyses in which mutant organisms are compared to nonmutant siblings can be especially problematic when the gene of interest is expressed in relatively few cells. Here, we describe the use of laser microdissection microarray to perform transcriptional profiling of the maize shoot apical meristem (SAM), a ~100-μm pillar of organogenic cells that is required for leaf initiation. Microarray analyses ...


Scanning Microarrays At Multiple Intensities Enhances Discovery Of Differentially Expressed Genes, David S. Skibbe, Xiujuan Wang, Xuefeng Zhao, Lisa A. Borsuk, Dan Nettleton, Patrick S. Schnable 2019 Iowa State University

Scanning Microarrays At Multiple Intensities Enhances Discovery Of Differentially Expressed Genes, David S. Skibbe, Xiujuan Wang, Xuefeng Zhao, Lisa A. Borsuk, Dan Nettleton, Patrick S. Schnable

Dan Nettleton

Motivation: Scanning parameters are often overlooked when optimizing microarray experiments. A scanning approach that extends the dynamic data range by acquiring multiple scans of different intensities has been developed.

Results: Data from each of three scan intensities (low, medium, high) were analyzed separately using multiple scan and linear regression approaches to identify and compare the sets of genes that exhibit statistically significant differential expression. In the multiple scan approach only one-third of the differentially expressed genes were shared among the three intensities, and each scan intensity identified unique sets of differentially expressed genes. The set of differentially expressed genes from ...


The B73 Maize Genome: Complexity, Diversity, And Dynamics, Patrick S. Schnable, Doreen Ware, Kai Ying, Cheng-Ting Yeh, Scott J. Emrich, Yi Jia, Ananth Kalyanaraman, An-Ping Hsia, Yan Fu, Sanzhen Liu, Alan M. Myers, Dan Nettleton, Srinivas Aluru 2019 Iowa State University

The B73 Maize Genome: Complexity, Diversity, And Dynamics, Patrick S. Schnable, Doreen Ware, Kai Ying, Cheng-Ting Yeh, Scott J. Emrich, Yi Jia, Ananth Kalyanaraman, An-Ping Hsia, Yan Fu, Sanzhen Liu, Alan M. Myers, Dan Nettleton, Srinivas Aluru

Dan Nettleton

We report an improved draft nucleotide sequence of the 2.3-gigabase genome of maize, an important crop plant and model for biological research. Over 32,000 genes were predicted, of which 99.8% were placed on reference chromosomes. Nearly 85% of the genome is composed of hundreds of families of transposable elements, dispersed nonuniformly across the genome. These were responsible for the capture and amplification of numerous gene fragments and affect the composition, sizes, and positions of centromeres. We also report on the correlation of methylation-poor regions with Mu transposon insertions and recombination, and copy number variants with insertions and ...


Digital Commons powered by bepress