ayyadevara, srinivas et al. (2019) International Worm Meeting "A novel microtubule-binding drug attenuates and reverses protein aggregation in animal models of Alzheimer's disease."

Kakraba, Samuel, Alla, Ramani, Penthala, Narsimha Reddy, Griffin, Sue, Ganne, Akshatha, Barger, Steven, Ayyadevara, Srinivas, Liu , Ling, Shmookler Reis, Robert, Balasubramaniam, Meenakshisundaram, Bommagani, Shoban Babu, Crooks, Peter

[International Worm Meeting, 2019]

Age-progressive neurodegenerative pathologies, including Alzheimer's disease, are distinguished and diagnosed by disease-specific components of intra- or extra-cellular aggregates. Increasing evidence suggests that neuroinflammation promotes protein aggregation, and is involved in the etiology of neurological diseases. We synthesized and tested analogues of the naturally occurring tubulin-binding compound, combretastatin A-4. One such analogue, PNR502, markedly reduced the quantity of Alzheimer-associated amyloid aggregates in the BRI-A?1-42 mouse model of Alzheimer's disease, while blunting the ability of the pro-inflammatory cytokine IL-1? to raise levels of amyloid plaque and its protein precursors in a neuronal cell-culture model. In transgenic C. elegans strains that express human A?1-42 in muscle or neurons, PNR502 rescued A?-induced disruption of motility (3.8-fold, p<0.0001) or chemotaxis (1.8-fold, p<0.05), respectively. Moreover, in C. elegans with neuronal expression of A?1-42, a single day of PNR502 exposure reverses the chemotaxis deficit by 54% (p<0.01), actually exceeding the protection from longer exposure. Moreover, continuous PNR502 treatment also extends nematode lifespan 23% (p?0.001). Given that PNR502 can slow, prevent, or reverse Alzheimer-like protein aggregation in human-cell-culture and animal models, and that its principal predicted and observed binding targets are proteins previously implicated in Alzheimer's, we propose that PNR502 has therapeutic potential to inhibit cerebral A?1-42 aggregation and prevent or reverse neurodegeneration.

Srinivas Ayyadevara et al. (2003) International Worm Meeting "Genetic and physical mapping of life-span QTLs in the C.elegans genome"

Robert Shmookler Reis, Sen Hou, Srinivas Ayyadevara, John Thaden, Rajani Ayyadevara, Anthony Vertino

[International Worm Meeting, 2003]

Several Quantitative Trait Loci (QTLs) influencing life span have been identified in the genome of C.elegans. Three of them - lsq3, lsq4b, and lsqXa - have been confirmed to exert the predicted trait effects in congenic lines constructed by 20 generations of back-crossing into one of the parental strains. By using genetic and physical mapping methods we narrowed the interval that was initially mapped on these chromosomes. Transposon Tc1 insertion-based and SNP (single-nucleotide polymorphism) markers were used to further narrow the QTL-spanning intervals to less than 1 Mb for two of lsq3 and lsq4. The most narrowly defined interval is that for lsq4b, which spans 230 kbp and contains just 22 definite protein-coding genes. We proceeded by a candidate gene cloning approach, sequencing several positionally and functionally implicated genes in the lsq4b interval to determine whether there is polymorphism for exon-coding-sequences or immediately adjacent upstream or intronic regions, differentiating between the strains known to differ functionally for lsq4b alleles.

Srinivas Ayyadevara et al. (2002) Mid-west Worm Meeting "Fine mapping of introgressed regions for longevity QTLs in C. elegans"

Rajani Ayyadevara, Srinivas Ayyadevara, Robert J Shmookler Reis, Vasudha Kondopally, John J Thaden

[Mid-west Worm Meeting, 2002]

QTL mapping for longevity in C. elegans, in 4 interstrain crosses, implicated a total of 13 life-span loci (each p<0.01 by permutation; 6 of the peak LOD scores were >8, 2 were > 20). Based on recapture statistics, the total number of loci of comparable effect is 13-30. For 4 longevity QTLs, the BO allele was backcrossed 20 generations into the other parental background. These, and late-arising recombinants, were used to create homozygous stocks, for which the varying introgressed regions were fine-mapped by Anchor-PCR Display (1) and SNP typing. We also attempted mapping by microarray analysis of allelic variants differing markedly in expression levels; this has proven less useful than SNP mapping at present. We assessed 5 "snip-SNPs" defined by the Plasterk group as dimorphic between Bristol-N2 and Hawaiian strain CB4856. Two of these loci, at 13.18 and 13.95 Mb on chromosome IV, were dimorphic at the same positions between strains CL2a (=N2) and Bergerac-BO. We then sequenced intermittent regions across one QTL interval, lsq4b, from parental strains Bergerac-BO, CL2a, and congenic-recombinant line SR708 -- using an ABI Prism 3100 capillary sequencer. We have found and confirmed 8 SNPs distinguishing Bergerac-BO from CL2a in the vicinity of lsq4b (see Figure 1), out of a total sequenced expanse of 7.3 kbp, averaging 1.1 SNP per kbp. This level is higher than the range (0.11-0.69 SNP per kbp) reported for four other strains relative to Bristol-N2 (1), suggesting that CL2a and Bergerac-BO may be more diverged (more distantly related to each other) than Bristol-N2 is diverged from the four strains evaluated, although regional variation in SNP density across the genome could also contribute (2). In our calculation of SNP frequency, we excluded 4 changes clustered inside a span of 8 nucleotides; with these included, the SNP frequency is 1.35 per kbp. We also used NCBI's BLASTN server (BLAST 2, ver. 2.2.3) to align Bristol-N2 sequences, ascertained by The C. elegans Sequencing Consortium, with the Bergerac-BO coding sequences determined for unc-22 (3) and unc-54 (4) genes following their identification by transposon-tagging mutagenesis (3,5). For unc-54, there were 4 nucleotide changes in 4,394 nucleotides (AT TA, T G, G -), a frequency of 0.91 SNPs per kbp, whereas more than 39 kbp of unc-22 aligned sequence revealed only 2 single-nucleotide deletions, both within oligo(A) runs (A3 A2 , A5 A4 ). These, and the single-base deletion (G -) noted above, are likely to be artefactual since they would disrupt the open reading frame. The agreement between strains with respect to unc-22 sequence is particularly remarkable in that this alignment included >13 kbp of codon-position-3 nucleotides, positions shown to diverge almost as rapidly as the bulk of intronic and intergenic sequences (2). These combined data support the presence of striking regional variation in the frequency of interstrain sequence polymorphisms.

Srinivas Ayyadevara et al. (2002) Mid-west Worm Meeting "QTL Mapping for Longevity: Segmental Association with Stress Resistance Phenotypes in C. elegans."

Robert J Shmookler Reis, John J Thaden, Srinivas Ayyadevara, Rajani Ayyadevara, Vasudha Kondapally

[Mid-west Worm Meeting, 2002]

We performed QTL mapping for loci governing C. elegans longevity, in 4 interstrain crosses (Bristol-N2, RC301, and CL2a Bergerac-BO, and Bristol-N2DH424) revealing 4- 11 significant QTLs each, and a total of 13 life-span loci (each p<0.01; most LOD scores >8). Four of these longevity QTLs were backcrossed 20 generations to introgress the Bergerac-BO allele into the other parental background. Recombinants arising in the last two generations were rendered homozygous for the introgressed region and were tested for longevity and stress resistance. Each QTL showed retention of the longevity phenotype -- conferring allelic effects on median life-span of 1.5-3.5 days at 20 C; three of these were also backcrossed 3 generations in the opposite direction, with similar allelic trait effects. Each QTL tested also produced marked allelic differences for two or three of the four stress-response traits tested: resistance to thermal stress, hydrogen peroxide, paraquat, or ultraviolet irradiation. Of these stresses, thermotolerance correlated best with longevity (r = 0.91), followed by peroxide resistance (r= 0.72), paraquat resistance (r= 0.67) and UV resistance (r= 0.19). The QTL on chromosome IV, lsq4b, is associated with thermotolerance and paraquat resistance (each showing a 1.7-fold allelic effect on median survival), as well as longevity (1.27-fold effect on median life span) -- all traits mapping within the same 0.9-Mb region -- whereas this locus affects peroxide tolerance only weakly, and UV resistance not at all. Segmental stress-resistance, as observed, contradicts the "general stress resistance" phenotype proposed previously for several long-lived mutants.1 The longevity QTL has now been narrowed to 0.23 Mb, positioned on the physical map by a combination of Anchor-PCR Display2 and SNP typing; it comprises 22 known protein-coding genes, 6 snRNA genes, and 19 predicted genes. Further partitioning of this QTL interval is underway.

Srinivas Ayyadevara et al. (2005) International Worm Meeting "Telomere Length and Telomerease Activity in Mutants with Extended Life-Span in Post Mitotic Metazoan Caenorhabditis elegans"

Masood A Shammas, Robert J Shmookler Reis, Srinivas Ayyadevara

[International Worm Meeting, 2005]

We determined telomere length and telomerase activity in long-lived mutants and wild-type strains of Caenorhabditis elegans. Telomere length had good correlation with the life-span in strains tested. Telomere length was increased in strains showing extended life span (daf-2 and daf 2:daf-12) relative to a wild-type strain with normal life span (Bristol-N2, DRM stock). A double mutant (daf-2:daf-16) of normal life span has a telomere length intermediate between wild type Bristol-N2 and the long-lived daf-2 mutant. Telomerase activity, however, was not detected in any adult worms and does not differ significantly in embryos among these strains. Endonuclease activity was found to be elevated in some of these strains compared to wild-type Bristol-N2 worms. Since the adult nematode is essentially post-mitotic apart from germline, we speculate that the observed correlation between longevity and telomere length might reflect differences persisting from the developmental period. Telomeric DNA may preferentially accumulate oxidative damage, and thus act as a signaling mediator for repair mechanisms, and/or for maintenance of gene silencing via chromatin condensation.

Srinivas Ayyadevara et al. (2003) International Worm Meeting "Fine Mapping of Quantitative Trait Loci Conferring Resistance to Heat-Shock and Ultraviolet Radiation in C. elegans"

Srinivas Ayyadevara, Ping Kang, Robert Shmookler Reis

[International Worm Meeting, 2003]

We used a novel Tc1-based fine mapping procedure and recombinant inbred (RI) lines to map Quantitative Trait loci (QTLs) for resistance to heat shock and ultraviolet radiation in Caenorhabditis elegans. RI lines, generated from a Bristol-N2 Bergerac-BO cross, were exposed to UV light or heated to 35C, and subsequent survival measured. The RI lines differed markedly with respect to resistance to either stress. Linkage of stress-resistance QTLs to Tc1-based markers was determined by composite interval mapping (Zeng 1994). Quantitative trait loci significantly affecting resistance to UV were positioned on chromosomes I, II and III, with peak LOD scores of 3.3, 9.1 and 3.5, respectively. We found three significant QTLs for heat shock resistance on chromosome IV, and one such QTL on the X chromosome. Two of these loci, one in the middle of chromosome IV (near stP35) and one near the left end of X (between stP41 and stP40) were close or identical to QTLs affecting life span, as determined in an earlier mapping study of recombinant inbred populations (Ayyadevara et al. 2001). All significance thresholds shown (horizontal lines in Figure) were 0.05 genome-wide false positive levels determined empirically by 1000 permutations of genotype with respect to phenotype for each trait mapping (Churchill and Doerge, 1994).

Srinivas Ayyadevara et al. (2005) International Worm Meeting "Life Span and Stress Resistance of C.elegans Are Increased by Expression of Gluthathione Transferase capable of Metabolizing the Lipid peroxidation Product 4-Hydroxynonenal."

Robert J Shmookler Reis, Srinivas Ayyadevara, Abhijit Dandapat, Piotr Zimniak, Sharda P Singh, Mark R Engle, Helen Benes, Cheryl F Lichti, Eva Liebau

[International Worm Meeting, 2005]

Ceanorhabditis elegans expresses a glutathione-S-transferase (GST-10) belonging to the Pi class, that has the ability to conjugate the lipid peroxidation product 4-hydroxynonenal (4 HNE). Transgenic C. elegans strains were generated in which the 5' flanking region and promoter of gst-10 were placed upstream of gst-10 and mGsta4 cDNAs, respectively. mGsta4 encodes the murine mGSTA4-4, an enzyme with high catalytic efficiency for 4 HNE. The localization of both transgenes, determined by immunostaining, was predominantly in a few cells in head and tail. 4 HNE-conjugating activity, assessed in worm lysates, was increased in worms transgenic for mGsta4 or gst-10, relative to controls. Conversely, 4 HNE-protein adducts decreased in the transgenics relative to controls, indicating that the transgenic enzymes were active and effective in limiting electrophilic damage by 4 HNE. Stress resistance and life span were increased in transgenic animals (5 independent lines each), compared to two independent control strains. Our results suggest that electrophilic damage by 4 HNE contributes to C. elegans aging and stress responses.

Srinivas Ayyadevara et al. (2007) International Worm Meeting "Ten-fold life extension in C.elegans by mutations that also greatly improve survival of oxidative and electrophilic stresses, but not hyperthermic stress."

Robert Shmookler Reis, Srinivas Ayyadevara, Puneet Bharill, Cagdas Tazearslan, John Thaden

[International Worm Meeting, 2007]

Life span is extended by diverse C. elegans mutations. The most longevitous mutations, conferring up to 2.6-fold longer survival, arise from disruption of insulinlike signaling. Mutations attenuating corresponding pathways also prolong life for other species, including fruitflies and mice, although to lesser degrees. C. elegans strains bearing homozygous nonsense mutations in the xls-1 gene mature slowly into adults of essentially normal size, appearance, and pharyngeal pumping rate. Their median survival times were 145-190 days in three experiments; both median and maximum adult lifespans are extended by 10-fold over N2DRM, a relatively long-lived wild type stock into which the null mutants were outcrossed. Xls-1-null adults, although not exceptionally thermotolerant, survive 4- to 7.5-fold longer in the presence of oxidative and electrophilic stresses, than worms with normal or weaker (less long-lived) alleles. These phenotypes are 25 - 75% reversed epistatically in double mutants with daf-16, which encodes a transcription factor thought to mediate all downstream effects of insulin-like signaling in these nematodes. We thus conclude that xls-1 mutations exert their effects in part through other pathways, in addition to insulin-like signaling. We propose a mechanism for these unprecedented gains in survival under both normal and toxic environments.

Srinivas Ayyadevara et al. (2001) International C. elegans Meeting "Phosphorylation profiles of a quantitative trait loci (QTLs) on chromosome III, IV, V and X controlling longevity of Caenorhabditis elegans"

Sen Hou, Anthony Vertino, John J Thaden, Robert J S Reis, Srinivas Ayyadevara

[International C. elegans Meeting, 2001]

We have identified several highly significant quantitative trait loci (QTLs) that affect adult life span of C. elegans . Life span QTLs (lsq's) present on chromosomes III, IV, V and X were back-crossed for 20 generations into one of the parental strains, to construct congenic (near-isogenic) lines. These backcrossed lines have only a short span of one chromosome that has been introduced into a uniform genetic background, and thus differ from the recurrent-parent genome only by this short region. Each of these congenic lines has now been demonstrated to differ significantly and reproducibly from the recurrent parent with respect to longevity. We have now performed in vitro phosphorylation studies on these lines, comparing congenic lines with recurrent parental strains. The patterns of protein phosphorylation produced by whole animal lysates in vitro show several labeled bands distinguishing two of the congenic lines ( on chromosomes III and IV) from their recurrent-parent. This assay thus may provide a powerful tool for use in gene mapping, facilitating the identification of proteins involved in longevity determination.

Balasubramaniam, Meenakshisundaram et al. (2013) International Worm Meeting "Role of amino-acid pool size in aging-related muscle atrophy."

Ayyadevara, Srinivas, Reis, Robert J Shmookler, Alla, Ramani, Balasubramaniam, Meenakshisundaram

[International Worm Meeting, 2013]

Skeletal muscle mass declines to varying degrees with age and this is a significant contributor to frailty, loss of mobility and increased mortality. Reduced muscle mass can result from a decrease in muscle synthesis and/or an increase in degradation, as a consequence of trauma, aging and many age-onset disorders. A previous NMR study reported that a long-lived mutant strain has elevated pool levels of several amino acids, in particular the branched-chain amino acids leucine, isoleucine, valine, phenylalanine, tyrosine and tryptophan. To learn whether specific amino acid pools are generally associated with improved muscle retention or lifespan across diverse longevity mutants, we have determined the free aminoacid levels in a panel of C.elegans longevity mutants.In our initial assay we found increased pools of several branched-chain amino acids in the long-lived mutant strains. Remarkably, dietary supplementation of these aminoacids reduced age-dependent sarcopenia and moderately extended life span for a wild-type strain. Based on these results in a model system, we predict that prolonged amino acid supplementation may enhance muscle mass, strength and function in older persons by increasing muscle growth and quality.