-
[
1987]
To my knowledge, a theory of "developmentally programmed aging" has never been explicitly stated, although the notion that aging has some relationship to development has certainly been proposed many times. In the preceding chapter (36), Dr. Hayflick has made a brief description of the central idea of developmental programming within aging. In order to discuss relevant evidence in this chapter, I would like to propose the following, somewhat more specific and operational definition: The theory of developmentally programmed aging posits that aging involves events controlled in ways recognizably similar to those that operate during development. This definition is perhaps a little less extreme than it might have been, since it uses the phrase "aging involves events" rather than the phrase "aging is caused by events." However, I think it captures most of the usual connotations of "developmentally programmed aging," and it at least has the virtue of testability. Of course, to test the theory, as defined, requires evidence of several sorts. In particular, it requires (a) that we understand how some aging events are controlled, (b) that we understand how some developmental events are controlled, and (c) that we know how to recognize whether there is or is not similarity between the two. A central message of what follows is that we are really only at the beginning of being able to test this theory, although some lines of approach do appear
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[
Cell,
1983]
The C. elegans genome contains a 1.7 kb repeated DNA sequence (Tc1) that is present in different numbers in various strains. In strain Bristol and 10 other strains analyzed, there are 20 +/- 5 copies of Tc1, and these are located at a nearly constant set of sites in the DNA. In Bergerac, however, there are 200 +/- 50 interspersed copies of Tc1 that have arisen by insertion of Tc1 elements into new genomic sites. The interspersed copies of Tc1 have a conserved, nonpermuted structure. The structure of genomic Tc1 elements was analyzed by the cloning of a single Tc1 element from Bergerac and the comparison of its structure with homologous genomic sequences in Bristol and Bergerac. Tc1 elements at three sites analyzed in Bergerac undergo apparently precise excision from their points of insertion at high frequency.
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[
Worm Breeder's Gazette,
1992]
Monoamine oxidase A and B are mitochondrial outer membrane flavoproteins best characterized in higher vertebrates, and their association with the nervous system has led to the belief that their most important function is a role in neurotransmitter amine metabolism. In spite of extensive efforts to understand the role of these enzymes in the nervous system, little progress has been made. This is in part due to the inherent complexity of the systems studied. Because the nervous system of Caenorhabditis elegans is relatively simple and well defined, I decided to investigate if MAO is present in C elegans. The biogenic amines octopamine, serotonin, and dopamine, presumptive neurotransmitters in the worm, are all substrates of MAO. It is therefore reasonable to believe that MAO is present in C. elegans. Although first experiments to spectrophotometrically detect MAO activity failed, immunological studies of whole worm extracts indicated its presence. Homogenates were examined by SDS-PAGE and Western blot analysis with sheep anti-human MAO A, rabbit anti-human MAO A and sheep anti-bovine MAO B antibodies. A strong and specific alkaline phosphatase reaction was obtained with both anti-human MAO A antibodies. No trace of a signal was detected with anti-bovine MAO B antibody or preimmune sera. The positive band migrated more slowly than the human control suggesting that the putative nematode MAO is about 5 to 7kDa larger than the human enzyme. Evidence for the presence of MAO in whole animals was found by culturing the nematode on agar plates seeded with E. coli OP50 and containing the specific MAO A suicide inhibitor clorgyline or the structurally similar specific MAO B inhibitor deprenyl. For assays, starved Bristol N2 hermaphrodites from a plate were transferred to give 5 to 6 individuals per test plate. Plates were sealed with paraffin film and incubated at 20 C and monitored for two weeks with a microscope at 100 and 200x power. Clorgyline inhibited growth of the worm at 2.5x10 -5Mwhile deprenyl showed inhibition at >1x10 but <1x10 -3M.The effect with clorgyline expressed at 25 M is a concentration 2000 times lower than was required to observe behavioral effects in similar incubation studies with exogenously added neurotransmitters (Horvitz et al., '82, Science 216,1014). The high concentration of amines required in these experiments was attributed to impermeability of the worm's cuticle. This suggests that inhibition of growth results from an even lower concentration of clorgyline entering the animal. In vitro, MAO A is rapidly inhibited by 1x10 -7Mclorgyline or 1x10 -5Mdeprenyl. In addition to the observation that worms stopped growing in the presence of clorgyline and bacteria, cessation of pharyngeal pumping was evident. It is possible that inactivation of MAO increases the concentration of octopamine in a neuron that controls inhibition of pharyngeal pumping (Horvitz et al., '82, ibid.). Growth may have ceased due to starvation. Treatment of octopamine-defective and other mutants with clorgyline and other drugs should shed light on this proposal. These preliminary experiments strongly suggest the C. elegans contains MAO, possibly of the A type, and that the enzyme plays an essential role in either the development or the normal functioning of this simple organism. We now plan to firmly establish the presence of MAO and its type and determine the mechanism of growth arrest as this most likely underlies the role of MAO and its mode of action in C. elegans.
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[
Evid Based Complement Alternat Med,
2020]
Background: Infections by microbes (viruses, bacteria, and fungi) and parasites can cause serious diseases in both humans and animals. Heavy use of antimicrobials has created selective pressure and caused resistance to currently available antibiotics, hence the need for finding new and better antibiotics. Natural products, especially from plants, are known for their medicinal properties, including antimicrobial and anthelmintic activities. Geoclimatic variation, together with diversity in ethnomedicinal traditions, has made the Himalayas of Nepal an invaluable repository of traditional medicinal plants. We studied antiviral, antibacterial, antifungal, and anthelmintic activities of medicinal plants, selected based upon ethnobotanical evidence. Methods: . Also, cytotoxicity was assessed on human hepatoma (Huh), rhabdosarcoma (RD), and Vero (VC) cell lines. Results: motility, comparable to levamisole. Conclusions: In countries like Nepal, with a high burden of infectious and parasitic diseases, and a current health system unable to combat the burden of diseases, evaluation of local plants as a treatment or potential source of drugs can help expand treatment options. Screening plants against a broad range of pathogens (bacteria, viruses, fungi, and parasites) will support bioprospecting in Nepal, which may eventually lead to new drug development.
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[
Nature,
1998]
Most metazoans occur as two sexes. Surprisingly, molecular analyses have hitherto indicated that sex-determining mechanisms differ completely between phyla. Here we present evidence to the contrary. We have isolated the male sexual regulatory gene
mab-3 from the nematode Caenorhabditis elegans and found that it is related to the Drosophila melanogaster sexual regulatory gene doublesex (dsx)2. Both genes encode proteins with a DNA-binding motif that we have named the 'DM domain'. Both genes control sex-specific neuroblast differentiation and yolk protein gene transcription; dsx controls other sexually dimorphic features as well. The form of DSX that is found in males can direct male-specific neuroblast differentiation in C. elegans. This structural and functional similarity between phyla suggests a common evolutionary origin of at least some aspects of sexual regulation. We have identified a human gene, DMT1, that encodes a protein with a DM domain and find that DMT1 is expressed only in testis. DMT1 maps to the distal short arm of chromosome 9, a location implicated in human XY sex reversal. Proteins with DM domains may therefore also regulate sexual development in mammals.
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[
International Worm Meeting,
2003]
Eukaryotic genomes from diverse species contain distinct patterns of homologous genes ordered along their chromosomes. Chromosomal patterns change when rearrangements such as translocations, duplications, deletions, or inversions occur. These observations raise two important questions. Are genes randomly distributed in genomes? If not, do chromosomal rearrangements have adaptive value? We are beginning to address these questions through studies of a sperm-sensing mechanism that controls the rate and efficiency of reproduction in C. elegans. Sperm stimulate oocyte meiotic maturation, oocyte mitogen-activated protein kinase activation, somatic gonadal sheath contraction, and spermathecal dilation using the major sperm protein (MSP) as a signaling molecule. We show that genes in these signaling pathways are nonrandomly distributed in the genome and cluster with twenty-eight msp genes located at three loci on chromosomes II and IV. Other tightly linked genes have been implicated in regulating MSP transcription or trafficking during spermatogenesis. We also detected overlapping, nonrandom distributions of genes that control the onset of oogenesis (via the translational regulation of
fem-3), but not of genes in other delineated pathways. Therefore, we have defined clusters of reproductive genes that function in common pathways. To evaluate the magnitude of these clusters, we used a global microarray-based strategy to determine the chromosomal distributions of genes with upregulated germline transcriptional profiles. Large nonrandom aggregations of sperm-enriched and germline-enriched genes colocalize with the chromosomal regions we defined by functional studies. By contrast, muscle-enriched or dauer-enriched genes are proportionately represented in these regions. Our results strongly support the hypothesis that reproductive genes are nonrandomly distributed in the C. elegans genome. To investigate the significance of these reproductive clusters, we examined chromosomal distributions of related genes in C. briggsae and other metazoan genomes. Comparative mapping and phylogenetic studies suggest that these clusters were built by large numbers of chromosomal rearrangements occurring in two temporal phases. Because rearrangements generated nonrandom patterns within the C. elegans genome, selection is predicted to drive this (re)distribution process. Therefore, chromosomal rearrangements may have adaptive value. We will discuss reasons why clustering may confer a selective advantage and implications for genome evolution.
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[
Worm Breeder's Gazette,
1986]
At the last worm meeting we reported the finding of a repetitive element in C. elegans that had strain number differences reminiscent of those found for the transposon Tc1. This new element was found in an experiment in which we looked for larger variants of Tc1, hoping to find a sequence that might be to Tc1 what the autonomous Ac element is to the non-autonomous Ds element in maize. Subsequent experiments in which we cloned several of the elements from Bergerac and Bristol phage libraries suggested that this is not the case. The new element, tentatively named Tc2, is not physically associated with Tc1 except in the single case in which we picked it up. Restriction maps of five of the members of the family do not reveal any simple pattern among them; e.g., they do not appear to be simple deletion variants of one 'master' form. We are currently pursuing a line of evidence which may enable us to prove conclusively that Tc2 is actively transposing in the germline of Bristol/Bergerac recombinants. A number of such recombinants were kindly sent to us by Ikue Mori and Don Moerman in Robert Waterston's lab at Washington University. These recombinants have either retained or lost a single well-mapped locus which confers germline transposition activity on Tc1 (as assayed by reversion of
unc-22(
st136::Tc1)). While doing Southern blot experiments to see if Tc1 activity correlates with a member of the Tc2 family, we noticed three cases in which recombinant strains contained Tc2 bands which are not present in either Bergerac or Bristol. It is possible that these bands represent new insertions into germline DNA. We are now cloning one of these bands in hopes of isolating an active version of Tc2. We will demonstrate that it is a new insertion (if it is) by using its flanking sequence to pull out its empty site from a parent strain.
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Schlicksupp A, Schmidt C, Simons A, Ruppert T, Bayer TA, Pipkorn R, Masters CL, Beyreuther K, Multhaup G, Cappai R, Reed J, White AR
[
Biochemistry,
2002]
The amyloid precursor protein (APP) copper-binding domain (CuBD) has been shown to reduce Cu(II) to Cu(I) and to mediate copper-induced oxidation in vitro. However, little is known about copper binding to the homologous domains of APP and APP family paralogs and orthologs (including amyloid precursor-like proteins from Drosophila melanogaster, Xenopus laevis, and Caenorhabditis elegans) and their effects on Cu-induced oxidation and Cu(I) formation. Here, we show that APP homologues with and without conserved histidine residues at positions 147, 149, and 151 all bind Cu(II). Oxidized peptides were the kinetically favored products of the redox reaction of CuBDs promoting the reduction of Cu(II) to Cu(I). These results reveal a molecular phylogeny-based divergence that has taken place between the ancestral Drosophila APPL and C. elegans APL-1 and the recently evolved APP lineage of CuBDs. Whereas higher species CuBDs have a decreased affinity for Cu(II) and high Cu(II) reducing activities, ancestral CuBDs form very tight binding sites for Cu(II) ions and have low Cu(II) reducing activities. Thus, the APP lineage displays a gain in activity toward promoting Cu(II) reduction and Cu(I) release. The findings suggests that the Cu(II)-binding equilibrium at the phylogenetic stage of Drosophila APPL and C. elegans APL-1 is shifted from the exchangeable Cu(II) pool to the tightly bound, nonexchangeable pool and that ancestral CuBDs may exert antioxidation activities in vivo. The more recently evolved homologues of human APP appear to take advantage of unique redox properties for yet unknown biological functions.
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[
Worm Breeder's Gazette,
1984]
Spermiogenesis in C. elegans involves a rapid transition from a non- motile, spherical spermatid to a motile, bipolar amoeboid spermatozoa. This activation can be induced in vitro by weak bases, monensin, and proteases (Ward, et. al., Dev Biol 98:70-79, 1983). Since calmodulin has been shown to play a major role in both motility systems and cytoskeletal organization in other organisms, it seemed logical that it might also play a role in sperm activation in C. elegans.To test this proposal we have compared the effects of two structurally unrelated calmodulin inhibitors, trifluoperazine and W-7, on sperm activation. Virgin E1490 males were hand dissected in buffer on acid- washed slides and a slide chamber was created by supporting the coverslip on Vaseline. Sperm activation was monitored using Nomarski optics on a Zeiss Universal microscope equipped with a time-lapse videotape recorder. The cells respond to the drugs differently at different drug concentrations. At the highest concentrations (100 m TFP and 500 m W7) , the spermatids showed either no response or lysed. There was no activation upon subsequent removal of the drug or the addition of 200 m/ml Pronase. At low concentrations (10 m - 20 m for both drugs), the spermatids showed no obvious drug response. In contrast, the addition of low concentrations of the drugs to active spermatozoa caused the pseudopods to stop moving and smooth out as they slowly 'melted back'. This effect is rapidly and fully reversible by alternately washing the drug in and out with buffer. The most interesting results were found in the intermediate range of 50 m for both drugs. This concentration caused the spermatids to form long spiky pseudopods which thickened with time but which lacked projections and were nonmotile. Subsequently, washing the drug out with buffer alone resulted in the formation of normal pseudopods. Normal pseudopods formed in the presence of Pronase as well as those generated after washing out 50 m calmodulin inhibitors with buffer responded to further drug additions (at concentrations of 50 m or less) by halting motility and 'melting back'. Thus these calmodulin inhibitors appear to initiate spermiogenesis although they also cause the 'melting back' of already formed normal pseudopods. Similar results were obtained when using another known calmodulin inhibitor, chlorpromazine; and yet its inactive analog, chlorpromazine-sulfoxide, had no effect at similar concentrations. One possible explanation for these results is that the differential drug effects reflect differences in binding constants of various calmodulin dependent enzymes in the cell. Our preliminary results from gel-overlay studies using [125I]-labelled hog brain calmodulin to probe gels of sperms proteins (Palfrey, et. al. PNAS 79:3780-3784, 1982) indicate that there may be several calmodulin binding proteins in sperm, some of which appear to be sperm-specific. In parallel with these studies, we are using other techniques to study calmodulin. As Marty Chalfie had mentioned to us earlier, we found that whole worms were also sensitive to calmodulin inhibitors. We hope to isolate calmodulin mutants by selecting animals which can survive and reproduce in the presence of these drugs. In addition, we will try to isolate the gene for calmodulin from C. elegans using a probe to electric eel calmodulin from A. R. Means (Lagace, et. al., J. Biol Chem 258:1684-1688, 1983). Furthermore, we will use indirect immunofluorescence with commercially available anti-calmodulin antibody to see if the localization of calmodulin changes during activation.
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[
International C. elegans Meeting,
1983]