GC3 biology in corn, rice, sorghum and other grasses

<p>Abstract</p> <p>Background</p> <p>The third, or wobble, position in a codon provides a high degree of possible degeneracy and is an elegant fault-tolerance mechanism. Nucleotide biases between organisms at the wobble position have been documented and correlated with the abundances of the complementary tRNAs. We and others have noticed a bias for cytosine and guanine at the third position in a subset of transcripts within a single organism. The bias is present in some plant species and warm-blooded vertebrates but not in all plants, or in invertebrates or cold-blooded vertebrates.</p> <p>Results</p> <p>Here we demonstrate that in certain organisms the amount of GC at the wobble position (GC₃) can be used to distinguish two classes of genes. We highlight the following features of genes with high GC₃content: they (1) provide more targets for methylation, (2) exhibit more variable expression, (3) more frequently possess upstream TATA boxes, (4) are predominant in certain classes of genes (e.g., stress responsive genes) and (5) have a GC₃content that increases from 5'to 3'. These observations led us to formulate a hypothesis to explain GC₃bimodality in grasses.</p> <p>Conclusions</p> <p>Our findings suggest that high levels of GC₃typify a class of genes whose expression is regulated through DNA methylation or are a legacy of accelerated evolution through gene conversion. We discuss the three most probable explanations for GC₃bimodality: biased gene conversion, transcriptional and translational advantage and gene methylation.</p

A Survey and Resource Materials on the Use of Oxygen Supplementation in Fish Culture.

Oxygen supplementation is the process by which naturally occurring dissolved oxygen (DO) is supplemented with enriched oxygen to restore or enhance DO levels in water. In aquaculture this is usually done with relatively pure oxygen and the result has significant potential to improve fish health, aid hatchery economic considerations, or both. For example, oxygen supplementation can preclude both hypoxia and gas bubble disease, as well as allow more fish to be reared in the same space or water or both. However, the concepts and technology in oxygen supplementation are evolving rapidly and direct communication with the user groups would foster technology transfer and improve implementation. Therefore we undertook and now report a survey of organizations that either currently use or plan to use oxygen supplementation. Additionally we included various pertinent material, including literature sources, lists of consultants and equipment manufacturers and some current research in oxygen supplementation

The Forum: Fall 2005

Fall 2005 journal of the Honors Program at the University of North Dakota. The issue includes stories, poems, essays and art by undergraduate students.https://commons.und.edu/und-books/1058/thumbnail.jp

Insights into corn genes derived from large-scale cDNA sequencing

We present a large portion of the transcriptome of Zea mays, including ESTs representing 484,032 cDNA clones from 53 libraries and 36,565 fully sequenced cDNA clones, out of which 31,552 clones are non-redundant. These and other previously sequenced transcripts have been aligned with available genome sequences and have provided new insights into the characteristics of gene structures and promoters within this major crop species. We found that although the average number of introns per gene is about the same in corn and Arabidopsis, corn genes have more alternatively spliced isoforms. Examination of the nucleotide composition of coding regions reveals that corn genes, as well as genes of other Poaceae (Grass family), can be divided into two classes according to the GC content at the third position in the amino acid encoding codons. Many of the transcripts that have lower GC content at the third position have dicot homologs but the high GC content transcripts tend to be more specific to the grasses. The high GC content class is also enriched with intronless genes. Together this suggests that an identifiable class of genes in plants is associated with the Poaceae divergence. Furthermore, because many of these genes appear to be derived from ancestral genes that do not contain introns, this evolutionary divergence may be the result of horizontal gene transfer from species not only with different codon usage but possibly that did not have introns, perhaps outside of the plant kingdom. By comparing the cDNAs described herein with the non-redundant set of corn mRNAs in GenBank, we estimate that there are about 50,000 different protein coding genes in Zea. All of the sequence data from this study have been submitted to DDBJ/GenBank/EMBL under accession numbers EU940701–EU977132 (FLI cDNA) and FK944382-FL482108 (EST)

Transcriptome sequencing of lentil based on second-generation technology permits large-scale unigene assembly and SSR marker discovery

<p>Abstract</p> <p>Background</p> <p>Lentil (<it>Lens culinaris </it>Medik.) is a cool-season grain legume which provides a rich source of protein for human consumption. In terms of genomic resources, lentil is relatively underdeveloped, in comparison to other Fabaceae species, with limited available data. There is hence a significant need to enhance such resources in order to identify novel genes and alleles for molecular breeding to increase crop productivity and quality.</p> <p>Results</p> <p>Tissue-specific cDNA samples from six distinct lentil genotypes were sequenced using Roche 454 GS-FLX Titanium technology, generating c. 1.38 × 10⁶expressed sequence tags (ESTs). <it>De novo </it>assembly generated a total of 15,354 contigs and 68,715 singletons. The complete unigene set was sequence-analysed against genome drafts of the model legume species <it>Medicago truncatula </it>and <it>Arabidopsis thaliana </it>to identify 12,639, and 7,476 unique matches, respectively. When compared to the genome of <it>Glycine max</it>, a total of 20,419 unique hits were observed corresponding to c. 31% of the known gene space. A total of 25,592 lentil unigenes were subsequently annoated from GenBank. Simple sequence repeat (SSR)-containing ESTs were identified from consensus sequences and a total of 2,393 primer pairs were designed. A subset of 192 EST-SSR markers was screened for validation across a panel 12 cultivated lentil genotypes and one wild relative species. A total of 166 primer pairs obtained successful amplification, of which 47.5% detected genetic polymorphism.</p> <p>Conclusions</p> <p>A substantial collection of ESTs has been developed from sequence analysis of lentil genotypes using second-generation technology, permitting unigene definition across a broad range of functional categories. As well as providing resources for functional genomics studies, the unigene set has permitted significant enhancement of the number of publicly-available molecular genetic markers as tools for improvement of this species.</p

The Golgin GMAP210/TRIP11 Anchors IFT20 to the Golgi Complex

Eukaryotic cells often use proteins localized to the ciliary membrane to monitor the extracellular environment. The mechanism by which proteins are sorted, specifically to this subdomain of the plasma membrane, is almost completely unknown. Previously, we showed that the IFT20 subunit of the intraflagellar transport particle is localized to the Golgi complex, in addition to the cilium and centrosome, and hypothesized that the Golgi pool of IFT20 plays a role in sorting proteins to the ciliary membrane. Here, we show that IFT20 is anchored to the Golgi complex by the golgin protein GMAP210/Trip11. Mice lacking GMAP210 die at birth with a pleiotropic phenotype that includes growth restriction, ventricular septal defects of the heart, omphalocele, and lung hypoplasia. Cells lacking GMAP210 have normal Golgi structure, but IFT20 is no longer localized to this organelle. GMAP210 is not absolutely required for ciliary assembly, but cilia on GMAP210 mutant cells are shorter than normal and have reduced amounts of the membrane protein polycystin-2 localized to them. This work suggests that GMAP210 and IFT20 function together at the Golgi in the sorting or transport of proteins destined for the ciliary membrane

Initial sequencing and analysis of the human genome

The human genome holds an extraordinary trove of information about human development, physiology, medicine and evolution. Here we report the results of an international collaboration to produce and make freely available a draft sequence of the human genome. We also present an initial analysis of the data, describing some of the insights that can be gleaned from the sequence.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62798/1/409860a0.pd

Role of retroviral genomic RNA sequences in the maintenance of balanced splicing: The avian sarcoma virus as a model system

Retroviruses utilize balanced splicing to express a full complement of gene products. Simple retroviruses, such as avian sarcoma virus (ASV), do not contain regulatory proteins that affect splicing and, thus, the control of balanced splicing is encoded entirely in cis on the viral RNA. The contribution of RNA elements to balanced splicing was examined through the combined use of in vivo and in vitro characterization of viral mutants. The investigations have demonstrated that the polypyrimidine tract (PPyT) can be an important component of balanced splicing and that this element may play different roles at different stages within the splicing reaction. Early in the splicing pathway the PPyT interacts with the splicing factor U2AF and this interaction is facilitated by sequences found in the downstream exon. Abrogation of this interaction results in diminished splicing and the accumulation of unspliced transcripts. Later in the splicing pathway, mutations can cause stalling of the splicing reaction as indicated by the accumulation of intermediates. This stalling correlates with increased association of the splicing factor SAP49 and increased accumulation of unspliced RNA. The mechanism by which stalled splicing reactions might promote the cytoplasmic accumulation of unspliced RNA was investigated. The results of these experiments demonstrate that the PPyT can play an important role late in the splicing reaction and that this element is likely to affect the binding of at least two proteins to the pre-mRNA. Examination of the sequence requirements of the PPyT reveals that they are complex and this likely reflects the binding of multiple proteins to this element. Lastly, a powerful in vivo selection system to address the role of RNA elements involved in splicing has been described. In combination with in vitro analysis this method provides insight into the mechanism of RNA splicing used by both viruses and the cell