Aliota MT et al. (2007) BMC Genomics "Mosquito transcriptome changes and filarial worm resistance in Armigeres subalbatus."

Fuchs JF, Christensen BM, Aliota MT, Mayhew GF, Chen CC

[BMC Genomics, 2007]

BACKGROUND: Armigeres subalbatus is a natural vector of the filarial worm Brugia pahangi, but it rapidly and proficiently kills Brugia malayi microfilariae by melanotic encapsulation. Because B. malayi and B. pahangi are morphologically and biologically similar, the Armigeres-Brugia system serves as a valuable model for studying the resistance mechanisms in mosquito vectors. We have initiated transcriptome profiling studies in Ar. subalbatus to identify molecular components involved in B. malayi refractoriness. RESULTS: These initial studies assessed the transcriptional response of Ar. subalbatus to B. malayi at 1, 3, 6, 12, 24, 48, and 72 hrs after an infective blood feed. In this investigation, we initiated the first holistic study conducted on the anti-filarial worm immune response in order to effectively explore the functional roles of immune-response genes following a natural exposure to the parasite. Studies assessing the transcriptional response revealed the involvement of unknown and conserved unknowns, cytoskeletal and structural components, and stress and immune responsive factors. The data show that the anti-filarial worm immune response by Ar. subalbatus to be a highly complex, tissue-specific process involving varied effector responses working in concert with blood cell-mediated melanization. CONCLUSION: This initial study provides a foundation and direction for future studies, which will more fully dissect the nature of the anti-filarial worm immune response in this mosquito-parasite system. The study also argues for continued studies with RNA generated from both hemocytes and whole bodies to fully expound the nature of the anti-filarial worm immune response.

Aliota MT et al. (2011) PLoS Negl Trop Dis "Filarial worms reduce Plasmodium infectivity in mosquitoes."

Chen CC, Fuchs JF, Aliota MT, Dagoro H, Christensen BM

[PLoS Negl Trop Dis, 2011]

BACKGROUND: Co-occurrence of malaria and filarial worm parasites has been reported, but little is known about the interaction between filarial worm and malaria parasites with the same Anopheles vector. Herein, we present data evaluating the interaction between Wuchereria bancrofti and Anopheles punctulatus in Papua New Guinea (PNG). Our field studies in PNG demonstrated that An. punctulatus utilizes the melanization immune response as a natural mechanism of filarial worm resistance against invading W. bancrofti microfilariae. We then conducted laboratory studies utilizing the mosquitoes Armigeres subalbatus and Aedes aegypti and the parasites Brugia malayi, Brugia pahangi, Dirofilaria immitis, and Plasmodium gallinaceum to evaluate the hypothesis that immune activation and/or development by filarial worms negatively impact Plasmodium development in co-infected mosquitoes. Ar. subalbatus used in this study are natural vectors of P. gallinaceum and B. pahangi and they are naturally refractory to B. malayi (melanization-based refractoriness). METHODOLOGY/PRINCIPAL FINDINGS: Mosquitoes were dissected and Plasmodium development was analyzed six days after blood feeding on either P. gallinaceum alone or after taking a bloodmeal containing both P. gallinaceum and B. malayi or a bloodmeal containing both P. gallinaceum and B. pahangi. There was a significant reduction in the prevalence and mean intensity of Plasmodium infections in two species of mosquito that had dual infections as compared to those mosquitoes that were infected with Plasmodium alone, and was independent of whether the mosquito had a melanization immune response to the filarial worm or not. However, there was no reduction in Plasmodium development when filarial worms were present in the bloodmeal (D. immitis) but midgut penetration was absent, suggesting that factors associated with penetration of the midgut by filarial worms likely are responsible for the observed reduction in malaria parasite infections. CONCLUSIONS/SIGNIFICANCE: These results could have an impact on vector infection and transmission dynamics in areas where Anopheles transmit both parasites, i.e., the elimination of filarial worms in a co-endemic locale could enhance malaria transmission.

Aliota MT et al. (2010) PLoS Negl Trop Dis "Mosquito transcriptome profiles and filarial worm susceptibility in Armigeres subalbatus."

Hillyer JF, Clark AK, Christensen BM, Fuchs JF, Chen CC, Rocheleau TA, Aliota MT

[PLoS Negl Trop Dis, 2010]

BACKGROUND: Armigeres subalbatus is a natural vector of the filarial worm Brugia pahangi, but it kills Brugia malayi microfilariae by melanotic encapsulation. Because B. malayi and B. pahangi are morphologically and biologically similar, comparing Ar. subalbatus-B. pahangi susceptibility and Ar. subalbatus-B. malayi refractoriness could provide significant insight into recognition mechanisms required to mount an effective anti-filarial worm immune response in the mosquito, as well as provide considerable detail into the molecular components involved in vector competence. Previously, we assessed the transcriptional response of Ar. subalbatus to B. malayi, and now we report transcriptome profiling studies of Ar. subalbatus in relation to filarial worm infection to provide information on the molecular components involved in B. pahangi susceptibility. METHODOLOGY/PRINCIPAL FINDINGS: Utilizing microarrays, comparisons were made between mosquitoes exposed to B. pahangi, B. malayi, and uninfected bloodmeals. The time course chosen facilitated an examination of key events in the development of the parasite, beginning with the very start of filarial worm infection and spanning to well after parasites had developed to the infective stage in the mosquito. At 1, 3, 6, 12, 24 h post infection and 2-3, 5-6, 8-9, and 13-14 days post challenge there were 31, 75, 113, 76, 54, 5, 3, 13, and 2 detectable transcripts, respectively, with significant differences in transcript abundance (increase or decrease) as a result of parasite development. CONCLUSIONS/SIGNIFICANCE: Herein, we demonstrate that filarial worm susceptibility in a laboratory strain of the natural vector Ar. subalbatus involves many factors of both known and unknown function that most likely are associated with filarial worm penetration through the midgut, invasion into thoracic muscle cells, and maintenance of homeostasis in the hemolymph environment. The data show that there are distinct and separate transcriptional patterns associated with filarial worm susceptibility as compared to refractoriness, and that an infection response in Ar. subalbatus can differ significantly from that observed in Ae. aegypti, a common laboratory model.

Yogev S et al. (2016) Neuron "Microtubule Organization Determines Axonal Transport Dynamics."

Cooper R, Fetter R, Shen K, Yogev S, Horowitz M

[Neuron, 2016]

Axonal microtubule (MT) arrays are the major cytoskeleton substrate for cargo transport. How MTorganization, i.e., polymer length, number, and minus-end spacing, is regulated and how it impinges on axonal transport are unclear. We describe a method for analyzing neuronal MT organization usinglight microscopy. This method circumvents the needfor electron microscopy reconstructions and is compatible with live imaging of cargo transport and MT dynamics. Examination of a C.elegans motor neuron revealed how age, MT-associated proteins, and signaling pathways control MT length, minus-end spacing, and coverage. In turn, MT organization determines axonal transport progression: cargoes pause at polymer termini, suggesting that switching MT tracks is rate limiting for efficient transport. Cargo run length is set by MT length, and higher MT coverage correlates with shorter pauses. These results uncover the principles and mechanisms of neuronal MT organization and its regulation of axonal cargo transport.

Shimada H et al. (2003) Trace Elements and Electrolytes "Metallothionein gene expression in the larvae of Caenorhabditis elegans is a potential biomarker for cadmium and mercury."

Ishibashi H, Shimada H, Kohra S, Tominaga N, Ura K, Mitsui Y, Arizono K

[Trace Elements and Electrolytes, 2003]

Previously, we reported that the induction of vitellogenin mRNA in the larvae of Caenorhabditis elegans (C. elegans) can be used as a biomarker for short-term screening of environmental endocrine disrupters. Therefore, the present study was designed to determine if the induction of metallothionein (MT) mRNA in the larvae of C. elegans would be a biomarker for short-term screening of heavy metals. The larvae were exposed to various concentrations of cadmium (Cd), mercury (Hg), zinc chloride (Zn), cupper chloride (Cu) or lead acetate (Pb) for 2h. Cd (1, 10 and 100 uM) and Hg (0.01, 0.1, 1 and 10 uM) exposures resulted in the marked induction of MT-I and MT-II mRNAs in the larvae of C. elegans as measured by reverse transcription polymerase chain reaction. The Cd and Hg induction of MT-II was higher than that of MT-I mRNA, and concentration-dependent increase was observed in MT-II but not in MT-I. Time course analysis for MT-I and MT-II expressions with Cd and Hg were also determined. Cd induction of MT-I and MT-II mRNAs reached a peak at 2 h after the exposure (10 uM), and the levels of MT-II were higher than that of MT-I. For Hg, an initial peak of induction of MT-II mRNA occurred 15 minutes after the exposure (0.1 uM), and the levels reached maximum by 2 h. The initial peak of induction of MT-I mRNA occurred much later (about 2 h after Hg exposure) than MT-II mRNA. These results indicate that the induction of MT-II mRNA in the larvae of C. elegans can be used as a potential biomarker

Xu A et al. (2019) Aging Cell "Microtubule regulators act in the nervous system to modulate fat metabolism and longevity through DAF-16 in C. elegans."

Chen L, Ko SH, Liu Z, Fisher AL, Xu A, Zhang Z

[Aging Cell, 2019]

Microtubule (MT) regulation is involved in both neuronal function and the maintenance of neuronal structure, and MT dysregulation appears to be a general downstream indicator and effector of age-related neurodegeneration. But the role of MTs in natural aging is largely unknown. Here, we demonstrate a role of MT regulators in regulating longevity. We find that loss of EFA-6, a modulator of MT dynamics, can delay both neuronal aging and extend the lifespan of C.elegans. Through the use of genetic mutants affecting other MT-regulating genes in C.elegans, we find that loss of MT stabilizing genes (including ptrn-1 and ptl-1) shortens lifespan, while loss of MT destabilizing gene hdac-6 extends lifespan. Via the use of tissue-specific transgenes, we further show that these MT regulators can act in the nervous system to modulate lifespan. Through RNA-seq analyses, we found that genes involved in lipid metabolism were differentially expressed in MT regulator mutants, and via the use of Nile Red and Oil Red O staining, we show that the MT regulator mutants have altered fat storage. We further find that the increased fat storage and extended lifespan of the long-lived MT regulator mutants are dependent on the DAF-16/FOXO transcription factor. Our results suggest that neuronal MT status might affect organismal aging through DAF-16-regulated changes in fat metabolism, and therefore, MT-based therapies might represent a novel intervention to promote healthy aging.

Xu, Aiping et al. (2017) International Worm Meeting "Neuronal Microtubule Stability Modulates Longevity in C. elegans."

Xu, Aiping, Chen, Lizhen

[International Worm Meeting, 2017]

Aging impacts the function of the nervous system and is the major risk factor for neurodegenerative diseases and is a fundamental problem in basic neuroscience and in human health. On the other hand, the nervous system corporate the organism's overall metabolism and affect homeostasis and longevity. MTs are essential cytoskeleton involved in cell division, shaping the cell and intracellular transport. Microtubule (MT) regulation is involved on several levels in neuronal function and maintenance of neuronal structure, and also appears to be a general downstream indicator and effector in age-dependent neurodegeneration. Here we hypothesized that neuronal MT stability regulates neuronal aging and organismal longevity. Consistent with previous reports, we found that MT-regulating genes played a role in maintaining neuronal integrity during aging. We then tested the lifespan of genetic mutants of MT-regulating genes in C. elegans and found that loss of MT stabilizing genes shortened lifespan, while loss of MT destabilizing genes enhanced lifespan. Decline in mobility is often associated with aging. Our data suggested that stabilizing neuronal MT enhance health span by improving mobility, and destabilization of MT accelerated age-dependent mobility decline. We further tested the effect of aging on MT-based intracellular transport by examining the localization of synaptic vesicles. We found MT-regulating genes and MT drugs could modulate the age-associated changes in vesicle localization. Finally we tested the genetic interaction between MT genes and aging regulators. Our data suggested that neuronal MT regulation might be involved in stress response to modulate longevity.

Okimoto R et al. (1994) J Mol Evol "The mitochondrial ribosomal RNA genes of the nematodes Caenorhabditis elegans and Ascaris suum: consensus secondary-structure models and conserved nucleotide sets for phylogenetic analysis."

Wolstenholme DR, Okimoto R, Macfarlane JL

[J Mol Evol, 1994]

The small- and large-subunit mitochondrial ribosomal RNA genes (mt-s-rRNA and mt-1-rRNA) of the nematode worms Caenorhabditis elegans and Ascaris suum encode the smallest rRNAs so far reported for metazoa. These size reductions correlate with the previously described, smaller, structurally anomalous mt-tRNAs of C. elegans and A. suum. Using primer extension analysis, the 5' end nucleotides of the mt-s-rRNA and mt-1-rRNA genes were determined to be adjacent to the 3' end nucleotides of the tRNA(Glu) and tRNA(His) genes, respectively. Detailed, consensus secondary-structure models were constructed for the mt-s-rRNA genes and the 3' 64% of mt-1-rRNA genes of the two nematodes. The mt-s-rRNA secondary-structure model bears a remarkable resemblance to the previously defined universal core structure of E. coli 16S rRNA: most of the nucleotides that have been classified as variable or semiconserved in the E. coli model appear to have been eliminated from the C. elegans and A. suum sequences. Also, the secondary structure model constructed for the 3' 64% of the mt-1-rRNA is similar to the corresponding portion of the previously defined E. coli 23S rRNA core secondary structure. The proposed C. elegans/A. suum mt-s-rRNA and mt-1-rRNA models include all of the secondary-structure element-forming sequences that in E. coli rRNAs contain nucleotides important for A-site and P-site (but not E-site) interactions with tRNAs. Sets of apparently homologous sequences within the mt-s-rRNA and mt-1-rRNA core structures, derived by alignment of the C. elegans and A. suum mt-rRNAs to the corresponding mt-rRNAs of other eukaryotes, and E. coli rRNAs were used in maximum-likelihood analyses. The patterns of divergence of metazoan phyla obtained show considerable agreement with the most prevalent metazoan divergence patterns derived

Swindell WR (2011) Ageing Res Rev "Metallothionein and the biology of aging."

Swindell WR

[Ageing Res Rev, 2011]

Metallothionein (MT) is a low molecular weight protein with anti-apoptotic properties that has been demonstrated to scavenge free radicals in vitro. MT has not been extensively investigated within the context of aging biology. The purpose of this review, therefore, is to discuss findings on MT that are relevant to basic aging mechanisms and to draw attention to the possible role of MT in pro-longevity interventions. MT is one of just a handful of proteins that, when overexpressed, has been demonstrated to increase mouse lifespan. MT also protects against development of obesity in mice provided a high fat diet as well as diet-induced oxidative stress damage. Abundance of MT is responsive to caloric restriction (CR) and inhibition of the insulin/insulin-like signaling (IIS) pathway, and elevated MT gene expression has been observed in tissues from fasted and CR-fed mice, long-lived dwarf mice, worms maintained under CR conditions, and long-lived daf-2 mutant worms. The dysregulation of MT in these systems is likely to have tissue-specific effects on aging outcomes. Further investigation will therefore be needed to understand how MT contributes to the response of invertebrates and mice to CR and the endocrine mutations studied by aging researchers.

Slice LW et al. (1990) J Biol Chem "Purification, characterization, and cDNA cloning of a novel metallothionein-like, cadmium-binding protein from Caenorhabditis elegans."

Slice LW, Rubin CS, Freedman JH

[J Biol Chem, 1990]

Caenorhabditis elegans adapted for survival in high concentrations of Cd(II) express a heavy metal binding protein designated C. elegans metallothionein-like protein or MT-Ce. This protein was purified to homogeneity and characterized. MT-Ce binds 6 mol of Cd(II)/mol protein. The sequence of 39 amino-terminal residues in MT-Ce was determined. A radiolabeled 41-mer oligonucleotide, designed from the partial MT-Ce sequence, was used in conjunction with sucrose gradient centrifugation to obtain size-fractionated poly(A+) RNA enriched in MT-Ce sequences. Subsequently, cloned cDNAs, corresponding to MT-Ce mRNA sequences, were isolated from a lambda ZapII cDNA library prepared from the enriched template mRNA. cDNA and protein sequence analysis revealed that MT-Ce comprises 62 amino acid residues and has a predicted Mr of 6462. Seventeen of the 18 Cys residues in the nematode cadmium-binding protein are included in Cys-X-Cys and X-Cys-Cys-X motifs that are characteristic of mammalian metallothioneins (MTs). However, the resemblance of MT-Ce to mammalian MTs is superficial. The amino acid sequence of MT-Ce is unique, and neither its putative alpha and beta domains nor its Cys residues can be readily aligned with the corresponding regions of other eukaryotic MTs. This suggests that MT-Ce is an example of convergent evolution. The MT-Ce mRNA level in nematodes that were selected and grown with Cd(II) concentrations that are lethal for wild-type worms, was 55-fold higher than the level of MT-Ce mRNA in wild-type C. elegans. Comparison of the sequences of MT-Ce cDNAs revealed the occurrence of two types of MT-Ce mRNA. Each contains an identical coding region, but the cDNAs diverge markedly in their 5'-untranslated regions. This suggests the possibilities of regulation by alternative splicing and/or the presence of multiple MT-Ce genes encoding a single protein, but controlled by different regulatory elements.