References: Hair growth and hair loss
bbsrc.ac.uk
Two recessive mutant alleles at CAN OF WORMS1 (COW1), a new locus involved in root hair morphogenesis, have been identified in Arabidopsis thaliana L. Heynh. Root hairs on Cow1- mutants are short and wide and occasionally formed as pairs at a single site of hair formation. The COW1 locus maps to chromosome 4. Root hairs on Cow1- plants form in the usual positions, suggesting that the phenotype is not the result of abnormal positional signals. Root hairs on Cow1- roots begin hair formation normally, forming a small bulge, or root hair initiation site, of normal size and shape and in the usual position on the hair-forming cell. However, when Cow1- root hairs start to elongate by tip growth, abnormalities in the shape and elongation rate of the hairs become apparent. Genetic evidence from double-mutant analysis of cow1-1 and other loci involved in root hair development supports our conclusion that COW1 is required during root hair elongation.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9390433&dopt=Abstract
Audiol Neurootol. 1996 Jan-Feb;1(1):3-11.
Nonlinearity of mechanoelectrical transduction of outer hair cells as the source of nonlinear basilar-membrane motion and loudness recruitment.
Preyer S, Gummer AW.
Department of Otolaryngology, University of Tubingen, Germany.
The sound-induced travelling wave in the mammalian cochlea is believed to be enhanced and sharpened by a positive-feedback mechanism, causing the passive, linear growth function of the basilar membrane (BM) to become nonlinear. Based on direct measurements of the receptor potential of isolated outer hair cells, it is shown here how nonlinear BM motion might be due predominantly to the nonlinear growth function of the receptor potential. Since intensity coding in the inner ear is supposed to depend on an interaction of nonlinear BM motion with afferent fibres of different synaptic thresholds, intensity coding is expected to be directly dependent on the mechanoelectrical transduction of outer hair cells (OHC). According to the present experimental data and the feedback concept of outer hair cell action, disruption of the mechanoelectrical transduction of OHC leads to both a reduction of gain and linearizing of the response; that is, to both hearing loss and loudness recruitment.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9390786&dopt=Abstract
Proc Natl Acad Sci U S A. 1997 Dec 9;94(25):13588-93.
Hypersensitivity of Ku80-deficient cell lines and mice to DNA damage: the effects of ionizing radiation on growth, survival, and development.
Nussenzweig A, Sokol K, Burgman P, Li L, Li GC.
Departments of Medical Physics and Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA.
We recently have shown that mice deficient for the 86-kDa component (Ku80) of the DNA-dependent protein kinase exhibit growth retardation and a profound deficiency in V(D)J (variable, diversity, and joining) recombination. These defects may be related to abnormalities in DNA metabolism that arise from the inability of Ku80 mutant cells to process DNA double-strand breaks. To further characterize the role of Ku80 in DNA double-strand break repair, we have generated embryonic stem cells and pre-B cells and examined their response to ionizing radiation. Ku80(-/-) embryonic stem cells are more sensitive than controls to gamma-irradiation, and pre-B cells derived from Ku80 mutant mice display enhanced spontaneous and gamma-ray-induced apoptosis. We then determined the effects of ionizing radiation on the survival, growth, and lymphocyte development in Ku80-deficient mice. Ku80(-/-) mice display a hypersensitivity to gamma-irradiation, characterized by loss of hair pigmentation, severe injury to the gastrointestinal tract, and enhanced mortality. Exposure of newborn Ku80(-/-) mice to sublethal doses of ionizing radiation enhances their growth retardation and results in the induction of T cell-specific differentiation. However, unlike severe combined immunodeficient mice, radiation-induced T cell development in Ku80(-/-) mice is not accompanied by extensive thymocyte proliferation. The response of Ku80-deficient cell lines and mice to DNA-damaging agents provides important insights into the role of Ku80 in growth regulation, lymphocyte development, and DNA repair.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9391070&dopt=Abstract
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