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Mutational Changes (mutational + change)
Selected AbstractsMutational changes in S-cone opsin genes common to both nocturnal and cathemeral Aotus monkeysAMERICAN JOURNAL OF PRIMATOLOGY, Issue 7 2007David H. Levenson Abstract Aotus is a platyrrhine primate that has been classically considered to be nocturnal. Earlier research revealed that this animal lacks a color vision capacity because, unlike all other platyrrhine monkeys, Aotus has a defect in the opsin gene that is required to produce short-wavelength sensitive (S) cone photopigment. Consequently, Aotus retains only a single type of cone photopigment. Other mammals have since been found to show similar losses and it has often been speculated that such change is in some fashion tied to nocturnality. Although most species of Aotus are indeed nocturnal, recent observations show that Aotus azarai, an owl monkey species native to portions of Argentina and Paraguay, displays a cathemeral activity pattern being active during daylight hours as frequently as during nighttime hours. We have sequenced portions of the S-cone opsin gene in A. azarai and Aotus nancymaae, the latter a typically nocturnal species. The S-cone opsin genes in both species contain the same fatal defects earlier detected for Aotus trivirgatus. On the basis of the phylogenetic relationships of these three species these results imply that Aotus must have lost a capacity for color vision early in its history and they also suggest that the absence of color vision is not compulsively linked to a nocturnal lifestyle. Am. J. Primatol. 69:757,765, 2007. © 2007 Wiley-Liss, Inc. [source] What constitutes a ,large' mutational change in phenotype?EVOLUTION AND DEVELOPMENT, Issue 5 2000Bryan Clarke No abstract is available for this article. [source] MINIREVIEW: On the use of metaphor to understand, explain, or rationalize redundant genes in yeastFEMS YEAST RESEARCH, Issue 3 2008Stephen Cooper Abstract The proposal that yeast, and cells in general, contains redundant genes that enable cells to survive mutational change has been supported by experiments and a strong metaphor. The redundant gene proposal is analyzed, and it is noted that there are many problems with the redundant gene model. An alternative metaphor is suggested to explain the genetic composition of a yeast culture. [source] HPRT mutations, TCR gene rearrangements, and HTLV-1 integration sites define in vivo T-cell clonal lineages,ENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 2-3 2005Mark Allegretta Abstract HPRT mutations in vivo in human T-lymphocytes are useful probes for mechanistic investigations. Molecular analyses of isolated mutants reveal their underlying mutational changes as well as the T-cell receptor (TCR) gene rearrangements present in the cells in question. The latter provide temporal reference points for other perturbations in the in vivo clones as well as evidence of clonal relationships among mutant isolates. Immunological studies and investigations of genomic instability have benefited from such analyses. A method is presented describing a T-cell lineage analysis in a patient with HTLV-1 infection. Lineage reconstruction of an in vivo proliferating HPRT mutant clone allows timing of the integration event to a postthymic differentiated cell prior to the occurrence of HPRT mutations. Environ. Mol. Mutagen., 2005. © 2005 Wiley-Liss, Inc. [source] Adaptive loss of ultraviolet-sensitive/violet-sensitive (UVS/VS) cone opsin in the blind mole rat (Spalax ehrenbergi)EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2002Z. K. David-Gray Abstract In previous studies, fully functional rod and long-wavelength-sensitive (LWS) cone photopigments have been isolated from the eye of the subterranean blind mole rat (Spalax ehrenbergi superspecies). Spalax possesses subcutaneous atrophied eyes and lacks any ability to respond to visual images. By contrast this animal retains the ability to entrain circadian rhythms of locomotor behaviour to environmental light cues. As this is the only known function of the eye, the rod and LWS photopigments are thought to mediate this response. Most mammals are dichromats possessing, in addition to a single rod photopigment, two classes of cone photopigment, LWS and ultraviolet-sensitive/violet-sensitive (UVS/VS) with differing spectral sensitivities which mediate colour vision. In this paper we explore whether Spalax is a dichromat and has the potential to use colour discrimination for photoentrainment. Using immunocytochemistry and molecular approaches we demonstrate that Spalax is a LWS monochromat. Spalax lacks a functional UVS/VS cone photopigment due to the accumulation of several deleterious mutational changes that have rendered the gene nonfunctional. Using phylogenetic analysis we show that the loss of this class of photoreceptor is likely to have arisen from the visual ecology of this species, and is not an artefact of having an ancestor which lacked a functional UVS/VS cone photopigment. We conclude that colour discrimination is not a prerequisite for photoentrainment in this species. [source] Maintaining a healthy SPANC balance through regulatory and mutational adaptationMOLECULAR MICROBIOLOGY, Issue 1 2005Thomas Ferenci Summary Stress protection is an important but costly contributor to bacterial survival. Two distinct forms of environmental protection share a common cost and a significant species-wide variability. Porin-mediated outer membrane permeability and the RpoS-controlled general stress response both involve a trade-off between self- preservation and nutritional competence, called the SPANC balance. Interestingly, different Escherichia coli strains exhibit distinct settings of the SPANC balance. It is tilted towards high stress resistance and a restricted diet in some isolates whereas others have broader nutritional capability and better nutrient affinity but lower levels of resistance. Growth- or stress-related selective pressures working in opposite directions (antagonistic pleiotropy) result in polymorphisms affecting porins and RpoS. Consequently, these important cellular components are present at distinct concentrations in different isolates. A generalized hypothesis to explain bacterial adaptation, based on the SPANC investigations, is offered. A holistic approach to bacterial adaptation, involving a gamut of regulation and mutation, is likely to be the norm in broadening the capabilities of a species. Indeed, there is unlikely to be a standard regulatory setting typical for all members of a species. Gene regulation provides a limited fine control for maintaining the right level of adaptation in a particular niche but mutational changes provide the coarse control for adaptation between the species-wide environments of free-living bacteria. [source] Quantitative proteomics and phosphoproteomics reveal novel insights into complexity and dynamics of the EGFR signaling networkPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 21 2008Sandra Morandell Abstract The epidermal growth factor receptor (EGFR/ErbB1/Her1) belongs to the ErbB family of receptor tyrosine kinases (RTKs) and is a key player in the regulation of cell proliferation, differentiation, survival, and migration. Overexpression and mutational changes of EGFR have been identified in a variety of human cancers and the regulation of EGFR signaling plays a critical role in tumor development and progression. Due to its biological significance the EGFR signaling network is a widely used model system for the development of analytical techniques. Novel quantitative proteomics and phosphoproteomics approaches play an important role in the characterization of signaling pathways in a time and stimulus dependent manner. Recent studies discussed in this review provide new insights into different aspects of EGFR signal transduction, such as regulation and dynamics of its phosphorylation sites, association with interaction partners and identification of regulated phosphoproteins. Correlation of data from functional proteomics studies with results from other fields of signal transduction research by systems biology will be necessary to integrate and translate these findings into successful clinical applications. [source] | ||||||||||