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Genetics, Vol. 181, April 2009, Copyright © 2009

ISSUE HIGHLIGHTS

Genetics of Sex-linked yellow in the Syrian hamster, pp. 1427–1436

Azita Alizadeh, Lewis Z. Hong, Christopher B. Kaelin, Terje Raudsepp, Hermogenes Manuel and Gregory S. Barsh

and

A domestic cat X chromosome linkage map and the sex-linked orange locus: Mapping of orange, multiple origins and epistasis over nonagouti, pp. 1415–1425

Anne Schmidt-Küntzel, George Nelson, Victor A. David, Alejandro A. Schäffer, Eduardo Eizirik, Melody E. Roelke, James S. Kehler, Steven S. Hannah, Stephen J. O'Brien and Marilyn Menotti-Raymond

Stripes and spots are of longstanding interest to zoologists, geneticists, and anyone who has read Rudyard Kipling's Just So Stories. A characteristic pattern known as Sex-linked yellow, Orange, or tortoiseshell exists in hamsters and cats but is curiously absent from other mammals. The work by ALIZADEH et al. and SCHMIDT-KÜNTZEL et al. use comparative genomic tools to characterize Sex-linked yellow in hamsters and Orange in cats, including their locations on the X chromosome, and their interactions with other mutations that perturb the melanocortin signaling pathway. Surprisingly, the hamster and cat mutations seem to have arisen independently.

Disruption of imprinting by Mutator transposon insertions in the 5' proximal regions of the Zea mays Mez1 locus, pp. 1229–1237

William J. Haun, Olga N. Danilevskaya, Robert B. Meeley and Nathan M. Springer

Imprinted genes are those that exhibit different levels of expression depending upon their parent of origin. This article provides evidence that proper expression of the maternal Mez1 allele of maize is required for silencing of the paternal allele, and that the differential methylation of the maternal and paternal alleles is not sufficient to cause imprinting in these alleles. Surprisingly, the altered expression levels of Mez1 and reactivation of paternal Mez1 alleles do not result in altered kernel morphology.

Episodic selection and the maintenance of competence and natural transformation in Bacillus subtilis, pp. 1521–1533

P. J. Johnsen, D. Dubnau and B. R. Levin

Horizontal gene transfer has played a fundamental role in the adaptive evolution of many species of bacteria. What are the selective forces responsible for the evolution and maintenance of the mechanism that enables horizontal gene transfer in bacteria: competence for DNA uptake and transformation? These investigators used a mathematical model and experiments with Bacillus subtilis to develop a new, eclectic, hypothesis for the maintenance of natural competence for transformation in bacteria, called "episodic selection".

High nucleotide divergence in developmental regulatory genes contrasts with the structural elements of olfactory pathways in Caenorhabditis, pp. 1387–1397

Richard Jovelin, Joseph P. Dunham, Frances S. Sung and Patrick C. Phillips

Chemosensation is an important means through which organisms interact with their environment, and its molecular basis is largely conserved across animals. The authors investigate the molecular evolution of two distinct chemosensory pathways within the nematode genus Caenorhabditis and find that most variation both within and between species is in regulatory rather than structural elements of the pathways. These results show that, contrary to the emerging paradigm in the evolution of development, important structural changes can accumulate in transcription factors and that the evolution of functional pathways must be considered within the context of broader gene network structure.

Identification of receptor-tyrosine-kinase-signaling target genes reveals receptor-specific activities and pathway branchpoints during Drosophila development, pp. 1335–1345

John R. Leatherbarrow and Marc S. Halfon

A poorly understood aspect of receptor tyrosine kinase (RTK) signaling is whether differences in the RTKs themselves or differences in other pathway components are responsible for the specific effects of signaling mediated by each RTK. By looking directly at the responses of individual target genes to RTK signaling in the same tissue, these authors present evidence suggesting that intrinsic differences among the RTKs are responsible for their distinct effects. This answers a long-standing question about the nature of RTK signaling and provides a rich set of assay targets for future studies.

Germline expression influences operon organization in the Caenorhabditis elegans genome, pp. 1219–1228

Valerie Reinke and Asher D. Cutter

Genes are not ordered randomly within the genome, with respect to their expression. These authors present evidence that expression in the germline of Caenorhabditis elegans plays a significant role in the organization of a substantial number of genes in operons. Thus, gene expression in a specific tissue can have profound effects on the evolution of genome organization.

Selective genotyping and phenotyping strategies in a complex trait context, pp. 1613–1626

Saunak Sen, Frank Johannes and Karl W. Broman

Selective genotyping and phenotyping strategies, where a subset of individuals is genotyped or phenotyped, can reduce the cost of quantitative trait loci experiments. The efficiency of such strategies has been established in simplified settings that do not adequately reflect the underlying etiology of complex traits. The authors analyze the efficiency of selective genotyping and phenotyping when multiple loci may contribute to a trait, possibly epistatically. They also consider the case when the phenotype distribution is not bell-shaped like the normal distribution. This helps researchers design better genotyping and phenotyping strategies that work better in more realistic and complex settings.

Heterochromatin-mediated association of achiasmate homologs declines with age when cohesion is compromised, pp. 1207–1218

Vijayalakshmi V. Subramanian and Sharon E. Bickel

Proper segregation of nonrecombinant homologous chromosomes during meiosis I in Drosophila oocytes relies on their association through pericentric heterochromatin. This study reveals that a protein required for sister-chromatid cohesion also promotes homolog association through centromere-proximal heterochromatin. This association deteriorates with age, resulting in increased missegregation of noncrossover chromosomes as well as those that have recombined.


Related articles in Genetics:

Heterochromatin-Mediated Association of Achiasmate Homologs Declines With Age When Cohesion Is Compromised
Vijayalakshmi V. Subramanian and Sharon E. Bickel
Genetics 2009 181: 1207-1218. [Abstract] [Full Text]  

Germline Expression Influences Operon Organization in the Caenorhabditis elegans Genome
Valerie Reinke and Asher D. Cutter
Genetics 2009 181: 1219-1228. [Abstract] [Full Text]  

Disruption of Imprinting by Mutator Transposon Insertions in the 5' Proximal Regions of the Zea mays Mez1 Locus
William J. Haun, Olga N. Danilevskaya, Robert B. Meeley, and Nathan M. Springer
Genetics 2009 181: 1229-1237. [Abstract] [Full Text]  

Identification of Receptor-Tyrosine-Kinase-Signaling Target Genes Reveals Receptor-Specific Activities and Pathway Branchpoints During Drosophila Development
John R. Leatherbarrow and Marc S. Halfon
Genetics 2009 181: 1335-1345. [Abstract] [Full Text]  

High Nucleotide Divergence in Developmental Regulatory Genes Contrasts With the Structural Elements of Olfactory Pathways in Caenorhabditis
Richard Jovelin, Joseph P. Dunham, Frances S. Sung, and Patrick C. Phillips
Genetics 2009 181: 1387-1397. [Abstract] [Full Text]  

A Domestic cat X Chromosome Linkage Map and the Sex-Linked orange Locus: Mapping of orange, Multiple Origins and Epistasis Over nonagouti
Anne Schmidt-Küntzel, George Nelson, Victor A. David, Alejandro A. Schäffer, Eduardo Eizirik, Melody E. Roelke, James S. Kehler, Steven S. Hannah, Stephen J. O'Brien, and Marilyn Menotti-Raymond
Genetics 2009 181: 1415-1425. [Abstract] [Full Text]  

Genetics of Sex-linked yellow in the Syrian Hamster
Azita Alizadeh, Lewis Z. Hong, Christopher B. Kaelin, Terje Raudsepp, Hermogenes Manuel, and Gregory S. Barsh
Genetics 2009 181: 1427-1436. [Abstract] [Full Text]  

Episodic Selection and the Maintenance of Competence and Natural Transformation in Bacillus subtilis
P. J. Johnsen, D. Dubnau, and B. R. Levin
Genetics 2009 181: 1521-1533. [Abstract] [Full Text]  

Selective Genotyping and Phenotyping Strategies in a Complex Trait Context
Saunak Sen, Frank Johannes, and Karl W. Broman
Genetics 2009 181: 1613-1626. [Abstract] [Full Text]