-
[
Yakugaku Zasshi,
2008]
Selenium (Se) is an essential trace element. Se is found as selenocysteine (Sec) in Se-proteins. Sec is the 21(st) amino acid, because Sec has its tRNA, the codon UGA and those components in its translational machinery. Sec UGA codon shares with major stop codon UGA. We purified Sec synthesizing enzymes, such as seryl-tRNA synthetase (SerRS), Sec synthetase (SecS) and selenophosphate synthetase (SePS). I described the procedures to prepare Sec tRNA, SerRS, SecS, SePS and [(75)Se]H(2)Se in detail. We clarified that SecS composed of two proteins, SecSalpha and SecSbeta. Sec synthesizing and incorporating systems present in Monela, Animalia and Protoctista but not in Plantae and Fungi. We showed that protozoa had Sec tRNA on which Sec was synthesized from Ser-tRNA by bovine and protozoa SecS. Some worms, such as Caenorhabditis elegans and Fasiola gigantica, also had Sec tRNA on which Sec was synthesized by bovine liver SecS or C. elegans enzymes. We showed recognition sites of mammalian Sec tRNA by SecS. The identitiy units of Sec tRNA are 9 bp aminoacyl- and 6 bp D-stems. This recognition is not the base-specific manner but the length-specific manner. From comparison of the phylogeny trees of Sec synthesizing system and translation system, we concluded that the evolution of Sec synthesizing system is older than that of the translation system.
-
[
Journal of Gerontology,
1999]
In recent years, oxidative damage to macromolecules has gained popularity as the basis of the molecular mechanism of aging. Martin proposes oxidative damage to macromolecules as one of the major public mechanisms of aging. Interest in modifications of protein by reactive oxygen species in aging was apparently introduced by Stadtman. Although various types of oxidative modifications can occur in proteins, carbonyl residues believed to be generated by metal catalyzed reaction or otherwise introduced by lysine, arginine and/or proline residues in vivo are often used as a marker of direct or
-
[
Cell,
2004]
Heterotrimeric G proteins are well known for their function in signal transduction downstream of seven transmembrane receptors. More recently, however, genetic analysis in C. elegans and in Drosophila has revealed a second, essential function of these molecules in positioning the mitotic spindle and attaching microtubules to the cell cortex. Five new publications in Cell (Afshar et al., 2004; Du and Macara, 2004 [this issue of Cell]; Hess et al., 2004), Developmental Cell (Martin-McCaffrey et al., 2004), and Current Biology (Couwenbergs et al., 2004) show that this function is conserved in vertebrates and-like the classical pathway- involves cycling of G proteins between GDP and GTP bound conformations.
-
[
J Am Soc Nephrol,
2005]
The nematode Caenorhabditis elegans has no kidney per se, yet "the worm" has proved to be an excellent model to study renal-related issues, including tubulogenesis of the excretory canal, membrane transport and ion channel function, and human genetic diseases including autosomal dominant polycystic kidney disease (ADPKD). The goal of this review is to explain how C. elegans has provided insight into cilia development, cilia function, and human cystic kidney diseases.
-
[
Mechanisms of Ageing & Development,
2005]
Recent results indicate that the longevity of both invertebrates and vertebrates can be altered through genetic manipulation and pharmacological intervention. Most of these interventions involve alterations of one or more of the following: insulin/IGF-I signaling pathway, caloric intake, stress resistance and nuclear structure. How longevity regulation relates to aging per se is less clear, but longevity increases are usually accompanied by extended periods of good health. How these results will translate to primate aging and longevity remains to be shown.
-
[
Exp Gerontol,
2006]
A powerful approach to understanding complex processes such as aging is to study longevity in organisms that are amenable to genetic dissection. The nematode Caenorhabditis elegans represents a superb model system in which to study the effects of mitochondrial function on longevity. Several mutant strains have been identified that indicate that mitochondrial function is a major factor affecting the organism''s lifespan. Taken as a group, these mutant strains indicate that metabolic rate, per se, only affects longevity indirectly. Mutations causing lowered metabolic rate potential are capable of decreasing or increasing longevity.
-
[
Journal of Gerontology,
1988]
Genetic approaches have been used to gain insights into many complex biological phenomena, but until recently most attempts to use genetic approaches to understand aging or senescence processes in metazoans have met with little success. The first review in this series (Martin and Tucker, 1988) surveyed model organisms used in the genetic analysis of aging; here I will review the analysis of life span and of the aging process by means of genetics. Problems inherent in the genetic analysis of aging will be reviewed first. Successful applications of genetics to the phenomena of aging will next be highlighted. Finally, I will present examples of ways in which both molecular and classical genetic approaches can be fruitfully and realistically applied to the study of the aging processes. Where applicable, misinterpretations and possible future directions will be noted.
-
[
FASEB J,
2011]
In this contribution to the series of reflective essays celebrating the 25th anniversary of The FASEB Journal, our task is to assess the growth of research on the biology of aging during this period and to suggest where we might be heading during the next 25 yr. A review of the literature suggests a healthy acceleration of progress during the past decade, perhaps largely due to progress on the genetics of longevity of model organisms. Progress on the genetics of health span in these model organisms has lagged, however. Research on the genetic basis of the remarkable interspecific variations in life span has only recently begun to be seriously addressed. The spectacular advances in genomics should greatly accelerate progress. Research on environmental effects on life span and health span needs to be accelerated. Stochastic variations in gene expression in aging have only recently been addressed. These can lead to random departures from homeostasis during aging.-Martin, G. M. The biology of aging: 1985-2010 and beyond.
-
[
Trends in Neurosciences,
1996]
Touch sensitivity in humans is dependent on highly specialized cutaneous nerve endings encapsulated in elaborate cellular structures such as the Pacinian, Ruffini and Meissner's corpuscles. Although the details of the encapsulations vary, the common theme involves the nerve endings making intimate mechanical linkages with the collagen-fiber networks contained within each capsule. Presumably, it is these external linkages with the membrane that serve to transmit and focus mechanical energy onto the mechanotransducers located in the nerve endings, and thus contribute to their low threshold and high mechanosensitivity. Extracellular mechanical linkages are also a feature of specific touch sensors in lower invertebrates, and thus appear to have evolved early in the animal kingdom. Indeed, it seems wherever high mechanosensitivity is required external mechanical linkages are present. In contrast, pain sensation, which is characterized by high threshold and low mechanosensitivity, is mediated by naked or free nerve endings, which lack elaborate external structures. Despite the existence of detailed ultrastructural information, the general inaccessibility of vertebrate touch and pain receptors has hampered studies on the molecules and molecular interactions underlying mechanotransduction in these cells. However, recent molecular-genetic analysis of touch-insensitive mutants in the tiny, free-swimming round worm, Caenorhabditis elegans, carried out by Martin Chalfie and colleagues, has begun to reveal detailed information on the molecular machinery of mechanotransduction. This information should provide useful clues and general principles for unravelling the molecular mechanisms underlying our own sensations of touch and pain.
-
[
Int J Parasitol,
1998]
Caenorhabditis elegans has become a popular model system for genetic and molecular research, since it is easy to maintain and has a very fast life-cycle. Its genome is small and a virtually complete physical map in the form of cosmids and YAC clones exists. Thus it was chosen as a model system by the Genome Project for sequencing, and it is expected that by 1998 the complete sequence (100 million bp) will be available. The accumulated wealth of information about C. elegans should be a boon for nematode parasitologists, as many aspects of gene regulation and function can be studied in this simple model system. A large array of techniques is available to study many aspects of C. elegans biology. In combination with genome projects for parasitic nematodes, conserved genes can be identified rapidly. We expect many new areas of fertile research that will lead to new insights in helminth parasitology, which are based not only on the information gained from C. elegans per se, but also from its use as a heterologous system to study parasitic genes.