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Calcium-binding proteins immunoreactivity in the human subcortical and cortical visual structures
- G. Leuba, K. Saini
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- Journal:
- Visual Neuroscience / Volume 13 / Issue 6 / November 1996
- Published online by Cambridge University Press:
- 02 June 2009, pp. 997-1009
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- Article
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The distribution of neurons and fibers immunoreactive (ir) to the three calcium-binding proteins parvalbumin (PV), calbindin D-28k (CB), and calretinin (CR) was studied in the human lateral geniculate nucleus (LGN), lateral inferior pulvinar, and optic radiation, and related to that in the visual cortex. In the LGN, PV, CR, and CB immunoreactivity was present in all laminae, slightly stronger in the magnocellular than in the parvocellular laminae for CB and CR. PV-ir puncta, representing transversally cut axons, and CR-ir fibers were revealed within the laminae and interlaminar zones, and just beyond the outer border of lamina 6 in the geniculate capsule. In the optic radiation both PV- and CR-immunoreactive neurons, puncta, and fibers were present. CB immunoreactivity was revealed in neurons of all laminae of the lateral geniculate nucleus, including S lamina and interlaminar zones. There were hardly any CB-ir puncta or fibers in the laminae, interlaminar zones, geniculate capsule, or optic radiation. In the lateral inferior pulvinar, immunoreactive neurons for the three calcium-binding proteins were present in smaller number than in the LGN, as well as PV-ir puncta and CR-ir fibers within the nucleus and in the pulvinar capsule. In the white matter underlying area 17, fibers intermingled with a few scattered neurons were stained for both PV and CR, but very rarely for CB. These fibers stopped at the limit between areas 17 and 18. Area 17 showed a dense plexus of PV-ir puncta and neurons in the thalamo-receptive layer IV and CR-ir puncta and neurons both in the superficial layers I-II, IIIC, and in layer VA. Cajal-Retzius CR-ir neurons were present in layer I. CB-ir puncta were almost confined to layer I-III and CB-ir neurons to layer II. Finally the superior colliculus exhibited mostly populations of PV and CR pyramidal-like immunoreactive neurons, mainly in the intermediate tier. These data suggest that in the visual thalamus most calcium-binding protein immunoreactive neurons project to the visual cortex, while in the superior colliculus a smaller immunoreactive population represent projection neurons.
Genetic information in ageing cells
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- By S. P. Modak, Department of Zoology, University of Poona, Pune, India;, D. D. Deobagkar, Department of Zoology, University of Poona, Pune, India;, G. Leuba-Gfeller, Institute of Anatomy-CHUV, University of Lausanne, Lausanne, Switzerland;, C. Gonet, Institute of Anatomy-CHUV, University of Lausanne, Lausanne, Switzerland;, S. Basu-Modak, Department of Zoology, University of Poona, Pune, India;
- A. H. Bittles, K. J. Collins
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- Book:
- The Biology of Human Ageing
- Published online:
- 06 August 2010
- Print publication:
- 20 March 1986, pp 17-32
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Summary
INTRODUCTION
Fertilization of an egg and the subsequent mixing of maternal and paternal chromosomal complements result in restitution of the diploid state composed of paired allelic sets of genes except, possibly, in the case of the male XY combination. The chromosomal basis of heredity and modality of the parent-to-progeny transfer by Mendelian genetic principles is well established. We also know that the molecular basis of heredity lies in the sequence of trinucleotides in DNA which is, thus, the primary carrier of genetic information. In each species the amount of DNA is maintained at a constant level and the law of DNA constancy is believed to imply that all cells in a lineage contain genetic information which is both qualitatively and quantitatively identical. It is well established that over 90% of the eukaryotic genome is noncoding but the “raisond'etre” for noncoding sequences remains totally obscure. The law of DNA constancy is violated in the case of rDNA amplification during ovogenesis, chromosome elimination from the somatic cell lineage in nematodes, polytenization of chromosomes in diptera larvae, and polyploidization in both animal and plant cells (for details see Davidson, 1976). Cytogenetic maps have been described for a number of species and it is believed that, similar to the germ cells, somatic cells maintain these with fidelity. Since the studies of Hozumi and Tonegawa (1976) on the location of IgG genes, evidence has been accumulating to suggest that the position of one or more genes need not be identical with reference to either each other or, with respect to the total cytogenetic map, even in cells derived from the same lineage.