Genetics and Genomics Commons^™

The Functions Of Animal Micrornas., Victor Ambros

Victor R. Ambros

MicroRNAs (miRNAs) are small RNAs that regulate the expression of complementary messenger RNAs. Hundreds of miRNA genes have been found in diverse animals, and many of these are phylogenetically conserved. With miRNA roles identified in developmental timing, cell death, cell proliferation, haematopoiesis and patterning of the nervous system, evidence is mounting that animal miRNAs are more numerous, and their regulatory impact more pervasive, than was previously suspected.

Food Based Approaches For A Healthy Nutrition In Africa, Mamoudou Hama Dicko

Pr. Mamoudou H. DICKO, PhD

The latest estimates of the FAO demonstrate the problems of the fight against hunger. These problems are manifested by the ever-increasing number of chronically undernourished people worldwide. Their numbers during the 1999-2001 period were estimated at about 840 million of which 798 million live in developing countries. Sub-Saharan Africa alone represented 198 million of those. In this part of Africa the prevalence of undernourishment ranges from 5-34%, causing growth retardation and insufficient weight gain among one third of the children under five years of age and resulting in a mortality of 5-15% among these children. Malnutrition resulting from undernourishment is …

The C. Elegans Heterochronic Gene Lin-46 Affects Developmental Timing At Two Larval Stages And Encodes A Relative Of The Scaffolding Protein Gephyrin., Anita Pepper, Jill Mccane, Kevin Kemper, Denise Yeung, Rosalind Lee, Victor Ambros, Eric Moss

Victor R. Ambros

The succession of developmental events in the C. elegans larva is governed by the heterochronic genes. When mutated, these genes cause either precocious or retarded developmental phenotypes, in which stage-specific patterns of cell division and differentiation are either skipped or reiterated, respectively. We identified a new heterochronic gene, lin-46, from mutations that suppress the precocious phenotypes caused by mutations in the heterochronic genes lin-14 and lin-28. lin-46 mutants on their own display retarded phenotypes in which cell division patterns are reiterated and differentiation is prevented in certain cell lineages. Our analysis indicates that lin-46 acts at a step immediately downstream …

Inheritance Of Trunk Banding In The Tetra (Gymnocorymbus Ternetzi Characidae), Jack Frankel

Jack Frankel

Decreased Expression Of Cu–Zn Superoxide Dismutase 1 In Ants With Extreme Lifespan, Joel D. Parker, Karen M. Parker, Barbara H. Sohal, Rajindar S. Sohal, Laurent Keller

Joel D Parker

Reactive oxygen species, the by-products of oxidative energy metabolism, are considered a main proximate cause of aging. Accordingly, overexpression of the enzyme Cu–Zn superoxide dismutase 1 (SOD1) can lengthen lifespan of Drosophila melanogaster in the laboratory. However, the role of SOD1 as a main determinant of lifespan has been challenged on the grounds that overexpression might be effective only in compromised genetic backgrounds. Moreover, interspecific comparisons show lower levels of antioxidant activities in longer-lived species, suggesting that life-span extension may evolve through less reactive oxygen species generation from the mitochondria rather than higher expression of SOD1. The tremendous variation in …

Expression Profiling Of Mammalian Micrornas Uncovers A Subset Of Brain-Expressed Micrornas With Possible Roles In Murine And Human Neuronal Differentiation., Lorenzo F. Sempere, Sarah Freemantle, Ian Pitha-Rowe, Eric Moss, Ethan Dmitrovsky, Victor R. Ambros

Victor R. Ambros

Background The microRNAs (miRNAs) are an extensive class of small noncoding RNAs (18 to 25 nucleotides) with probable roles in the regulation of gene expression. In Caenorhabditis elegans, lin-4 and let-7 miRNAs control the timing of fate specification of neuronal and hypodermal cells during larval development. lin-4, let-7 and other miRNA genes are conserved in mammals, and their potential functions in mammalian development are under active study. Results In order to identify mammalian miRNAs that might function in development, we characterized the expression of 119 previously reported miRNAs in adult organs from mouse and human using northern blot analysis. Of …

Mer1p Is A Modular Splicing Factor Whose Function Depends On The Conserved U2 Snrnp Protein Snu17p, Marc Spingola, Javier Armisen, Manuel Ares

Marc Spingola

A Short History Of A Short Rna, Victor Ambros, Rosalind Lee, Rhonda Feinbaum

Victor R. Ambros

Comment on: The C. elegans heterochronic gene lin-4 encodes small RNAs with antisense complementarity to lin-14. [Cell. 1993]

Applications Of Transposable Elements In Fish For Transgenesis And Functional Genomics, Perry B. Hackett, Karl J. Clark, Stephen C. Ekker, Jeffrey J. Essner

Jeffrey J. Essner

Transgenic fish were first made more than 30 years ago. Since then a variety of methods and const ructs have been tested for introducing genetic sequences into fish for scientitlc investigations as well as commercial purposes. Here we review transposable clements and t heir applications in fish. Transposons can be used to deliver genes to chromosomes to confer new traits or as insertional agents and traps to uncover the functions and expression patterns of natural genes in chromosomes. Two DNA transposons have been characterized for transposon-based gene transfer and insertional mutagenesis. The t1rst is d1e Sleeping Beauty transposon system that …

Heterogeneous Evolutionary Processes Affect R Gene Diversity In Natural Populations Of Solanum Pimpinellifolium, Ana Lucia Caicedo, B. A. Schaal

Ana Lucia Caicedo

Resistance (R) genes of plants are responsible for pathogen recognition and encode proteins that trigger a cascade of responses when a pathogen invades a plant. R genes are assumed to be under strong selection, but there is limited knowledge of the processes affecting R gene diversity in the wild. In this study, DNA sequence variation of Cf-2 homologs was surveyed in populations of Solanum pimpinellifolium, a wild relative of the cultivated tomato. The Cf-2 locus is involved in resistance to strains of the fungus Cladosporium fulvum. At least 26 different Cf-2 homologs were detected in natural populations of S. pimpinellifolium. …

Epistatic Interaction Between The Arabidopsis Fri And Flc Flowering Time Genes Generates A Latitudinal Cline In A Life History Trait, Ana Lucia Caicedo, J. R. Stinchcombe, K. M. Olsen, J Schmitt, M. D. Purugganan

Ana Lucia Caicedo

Epistatic gene interactions are believed to be a major factor in the genetic architecture of evolutionary diversification. In Arabidopsis thaliana, the FRI and FLC genes mechanistically interact to control flowering time, and here we show that this epistatic interaction also contributes to a latitudinal cline in this life history trait within the species. Two major FLC haplogroups (FLCA and FLCB ) are associated with flowering time variation in A. thaliana in field conditions, but only in the presence of putatively functional FRI alleles. Significant differences in latitudinal distribution of FLC haplogroups in Eurasia and North Africa also depend on the …

Molecular Defects In The Β-Globin Gene Identified In Different Ethnic Groups/Populations During Prenatal Diagnosis For Β-Thalassemia: A Malaysian Experience, Maryanne Tan

Mary Anne Tan Jin Ai

β-thalassemia is the most-common genetic disorder of hemoglobin synthesis in Malaysia, and about 4.5% of the population are heterozygous carriers of the disorder. Prenatal diagnosis was performed for 96 couples using the Amplification Refractory Mutation System and Gap- Polymerase Chain Reaction. We identified 17 β-globin defects-initiation codon for translation (T-G), -29 (A-G), - 28 (A-G), CAP +1 (A-C), CD 8/9 (+G), CD 15 (G-A), CD 17 (A-T), CD 19 (A-G), Hb E (G-A), IVS1-1 (G-T), IVS1- 5 (G-C), CD 41/42 (-CTTT), CD 71–72 (+A), IVS2-654 (CT), poly A(A-G), 100-kb Gγ(Aγδβ)° and 45-kb Filipino deletions. The 192 β-alleles studied comprised Chinese …

Identification Of Micrornas And Other Tiny Noncoding Rnas By Cdna Cloning, Victor Ambros, Rosalind Lee

Victor R. Ambros

MicroRNAs (miRNAs) and other small RNAs can be identified by cloning and sequencing cDNAs prepared from the ∼22-nt fraction of total RNA. Methods are described for the construction of cDNA libraries from small noncoding RNAs through the use of T4 RNA ligase, reverse transcriptase, and polymerase chain reaction. cDNAs are cloned in λ or plasmid vectors, and the sequences are compared to annotated genomic sequence databases, and analyzed by RNA folding programs to distinguish miRNA sequences from other small RNAs of similar size. Northern blot hybridization is used to confirm the expression of small RNAs in vivo.

Human Genetic Variation And Health: New Assessment Approaches Based On Ethnogenetic Layering, Fatimah Linda Collier Jackson

Fatimah Linda Collier Jackson