Nelson GA et al. (1985) Worm Breeder's Gazette "effects of heavy ion irradiation on C elegans."

Nelson GA, Hammen RF

[Worm Breeder's Gazette, 1985]

We have been investigating the effects of heavy ion irradiation on C. elegans using the Lawrence Berkeley Laboratory's Bevalac accelerator as a source of ions of various charge, energy and fluence. To date, ions of C, Ne, Ar, Fe and La have been used to irradiate N2 and JP10 ( eT1 balanced over dpy-18 and unc-46, of Rosenbluth, et. al., Genetics 109: 493) in order to characterize: 1) lethal mutation rates and structures vs. fluence and LET (linear energy transfer), and 2) fertility and gonad development vs. fluence, LET and target size (cell number in gonad primordia). The goals are to understand how heavy ion mechanisms of mutagenesis and cell killing are related to their LET, charge, velocity and tract structure and to compare these mechanisms to those for gamma & X-rays, which deposit energy in a more uniform fashion. For example, with respect to forward lethal mutation rate, 495 MeV/amu Fe ions at a fluence of 3x10+E7/cm^2 (three to four hits per gonad nucleus) are roughly equivalent to 2x10+E10 Co-60 gamma photons (2400 hits per gonad nucleus or 1000 rads). A brief summary of our findings to date is: (1) Mutation rate in the eT1 balanced region of LG III and LG V (strain JP10) is strongly dependent on LET below 100 KeV/ m and at three hits per cell reaches 8% of F1's at LET = 1100 KeV/ m. (2) At LET = 198 KeV/ m the lethal mutation rate in JP10 in the dose range 32 to 1600 'rad equivalents' ( Note that rads is a misleading unit for heavy ion radiation as it takes no account of track structure) is linear and equal to approximately 0.6% of F1's per 'rad'. (3) A large fraction of ion- induced lethals have altered segregation patterns. (4) Fertility in N2 irradiated as larvae is strongly dependent on LET and gonad size. The LET effect is maximum at about 100 KeV/ m and gonads with approximately 30-50 cells are most sensitive. Larvae with gonads of greater than 100 cells produce many males indicating survival of cells with sublethal damage to LG X. HELP! We are trying to find ways of immobilizing worms for extended periods of time (e.g., one week) in order to correlate particle tracks with worms and worm parts. The best we can do is to keep dauers in 3% agarose at 11 C, but we want to hold worms at 20-22 C. Suggestions would be most welcome-call GN @ (818) 354-4401.

Dawe AS et al. (2008) Bioelectromagnetics "Continuous wave and simulated GSM exposure at 1.8 W/kg and 1.8 GHz do not induce hsp16-1 heat-shock gene expression in Caenorhabditis elegans."

Nylund R, Leszczynski D, de Pomerai DI, Dawe AS, Kuster N, Reader T

[Bioelectromagnetics, 2008]

Recent data suggest that there might be a subtle thermal explanation for the apparent induction by radiofrequency (RF) radiation of transgene expression from a small heat-shock protein (hsp16-1) promoter in the nematode, Caenorhabditis elegans. The RF fields used in the C. elegans study were much weaker (SAR 5-40 mW kg(-1)) than those routinely tested in many other published studies (SAR approximately 2 W kg(-1)). To resolve this disparity, we have exposed the same transgenic hsp16-1::lacZ strain of C. elegans (PC72) to higher intensity RF fields (1.8 GHz; SAR approximately 1.8 W kg(-1)). For both continuous wave (CW) and Talk-pulsed RF exposures (2.5 h at 25 degrees C), there was no indication that RF exposure could induce reporter expression above sham control levels. Thus, at much higher induced RF field strength (close to the maximum permitted exposure from a mobile telephone handset), this particular nematode heat-shock gene is not up-regulated. However, under conditions where background reporter expression was moderately elevated in the sham controls (perhaps as a result of some unknown co-stressor), we found some evidence that reporter expression may be reduced by approximately 15% following exposure to either Talk-pulsed or CW RF fields. Bioelectromagnetics (c) 2007 Wiley-Liss, Inc.

Gao Y et al. (2016) PLoS One "A Genome-Wide mRNA Expression Profile in Caenorhabditis elegans under Prolonged Exposure to 1750MHz Radiofrequency Fields."

Wu T, Yu Z, Gao Y, Zhang C, Lu Y, Li Z, Yi J, Gao D

[PLoS One, 2016]

OBJECTIVE: C. elegans has been used as a biomonitor for microwave-induced stress. However, the RF (radiofrequency) fields that have been used in previous studies were weak (1.8W/kg), and the bio-effects on C. elegans were mostly negative or ambiguous. Therefore, this study used more intense RF fields (SAR = 3W/kg) and longer time course of exposure (60h at 25C, L1 stage through adult stage) to investigate the biological consequences of 1750 MHz RF fields in wild-type worms. METHODS: The growth rates and lifespans of RF-exposure group and the control group were carefully recorded. RNA samples were collected at L4 (35h) and gravid adult (50h) stages for further high-throughput sequencing, focusing on differences between the RF-exposure and the sham control groups. RESULTS: The RF-exposed and sham control groups developed at almost the same rate and had similar longevity curves. In L4 stage worms, 94 up-regulated and 17 down-regulated genes were identified, while 186 up-regulated and 3 down-regulated genes were identified in adult stage worms. GO analysis showed that the differentially expressed genes at 35h were associated with growth, body morphogenesis and collagen and cuticle-based development. Genes that were linked to growth rate and reproductive development were differentially expressed at 50h. Some embryonic and larval development genes in the offspring were also differentially expressed at 50h. Ten genes were differentially expressed at both 35h and 50h, most of which were involved in both embryonic and larval developmental processes. Although prolonged RF fields did not induce significant temperature increase in RF exposure groups, the temperature inside worms during exposure was unknown. CONCLUSIONS: No harmful effects were observed in prolonged exposure to 1750 MHz RF fields at SAR of 3W/kg on development and longevity of C. elegans. Although some differentially expressed genes were found after prolonged RF exposure, these differences were ascribed to oscillating gene expression patterns in L4 and gravid adult worms. It was also difficult to rule out a weak thermal effect caused by prolonged RF exposure inside the worms.

Yoon CH et al. (1996) Worm Breeder's Gazette "Genetic interactions between sli-1 and let-60 ras."

Sternberg PW, Yoon CH

[Worm Breeder's Gazette, 1996]

sli-1 is a negative regulator of let-23-mediated vulval induction and encodes a protein similar to the mammalian proto-oncoprotein c-Cbl (1). Reduction-of-function (rf) mutations in sli-1 suppress the vulvaless (Vul) phenotype associated with severe reduction-of-function, but not null, mutations of let-23 (2). let-60 ras acts downstream in the signal transduction process initiated by LET-23. Initial studies have shown that sli-1 has only a weak suppression of the slight Vul phenotype associated with the let-60(rf) mutation, n2021 (2). We have furthered this study to more exactly determine how sli-1 interacts with let-60. We used four severe let-60(rf) alleles defined by Beitel et al.(3): n1876, n2022, n2034, n2035. Animals bearing any of these four let-60(rf) alleles display partial lethality as segregants from heterozygous mothers. Lethality is essentially 100 % for F2 homozygotes of these four alleles, indicating that the partial penetrance of lethality in F1 homozygotes is due to maternal rescue from the let-60(+) wild-type copy in the heterozygous mothers. We scored vulval induction in F1 homozygotes of these four let-60(rf) alleles in sli-1(+) and sli-1(rf) backgrounds. We used the sli-1(rf) reference allele, sy143. We find that sli-1(sy143) does not suppress the Vul phenotype associated with severe let-60(rf) mutations. For example, n2035 is suppressed from 0.016 induced VPCs/animal (n=62) in a sli-1(+) background to 0.034 induced VPCs/animal (n=87) in a sli-1(sy143) background.

Nelson GA et al. (1985) International C. elegans Meeting "effect of heavy ion irradiation on C elegans."

Nelson GA, Benton ER, Hammen RF

[International C. elegans Meeting, 1985]

Nelson GA et al. (1984) Worm Breeder's Gazette "untitled."

Nelson GA, Dyer M, Hammen RF

[Worm Breeder's Gazette, 1984]

I've just begun to do some radiobiology using heavy ions from the Berkeley Bevalac accelerator as a way of modeling cosmic rays. NASA is interested in some biological dosimetry for heavy particles such as are encountered in earth orbit on the shuttle. Because of their true track structure, measurements in units such as rads and roentgens have dubious utility. Below are some preliminary results from iron irradiation experiments which looked for twitchers using Don Moerman and Dave Baillie's nicotine trick and some lethals using Raja Rosenbluth's eT1 balancer technique. The particles are highly mutagenic and I hope to eventually describe the types and extents of lesions caused by single particle interactions. An experiment using the BEVALAC accelerator at Lawrence Berkeley Laboratory was carried out on June 17, 1984. The purpose of this experiment was to familiarize us with the operation of the facility and to demonstrate the proof of concept that mutations could be induced in C. elegans using energetic heavy ions from the accelerator. Several tests were carried out but two are especially relevant here: 1) the induction of 'twitcher' mutants in gene unc-22 and, 2) the induction of lethal mutations in cross-over suppressed regions of chromosomes III and V using a reciprocal translocation strain. We were able to isolate 4 unc-22 mutants from 1965 N2 worms with gonads containing nominally 4, 10 and 30 cells with equivalent radiation doses of 30.02, 3.24 and 228.9 rads respectively. Several instances of male 'jackpots' were also noted. (A male 'jackpot' is the appearance of large groups of F1 males in broods of virgin hermaphrodites presumably due to induced X-chromosome loss; typical jackpots were 7 to 17 males per plate of 10 PO's whereas 0, 1 or 2 is normal). 6 lethal mutations and one long mutation were isolated from 96 adult worms tripley heterozygous for dpy-18 III, unc-46 V and the reciprocal translocation eT1(III;V) using an equivalent radiation dose of 3D.n2 rads. The type of radiation used was a beam of completely ionized iron particles having an energy of 445 MeV per nucleon or a total of 24.85 GeV per particle. The linear energy transfer of these particles was determined to be 198 KeV/micron and particles were delivered in pulses such that total fluence varied from about 10+E5 to 10+E7 particle tracks per cm2. Radiation characteristics were determined by Dr. E.V. Benton using CR-39 plastic radiation detector foils. We concluded that heavy ions are highly mutagenic in C. elegans and that the assays proposed in this proposal are capable of detecting genetic lesions induced by them. Work is in progress to determine the locations and nature of the new mutations. Confirming studies using alpha particles from Polonium - 210 also demonstrated the effectiveness of high LET particles. Mutations in unc-22 as well as several 'dumpy' and 'cell lineage defective' genes were induced with alpha particles using 1st stage larvae or dauer larvae as targets. The accompanying figure summarizes the BEVALAC results. [No accompanying figure]

Simpson VJ et al. (1986) Nucleic Acids Res "Caenorhabditis elegans DNA does not contain 5-methylcytosine at any time during development or aging."

Hammen RF, Simpson VJ, Johnson TE

[Nucleic Acids Res, 1986]

DNA, isolated from age-synchronous senescent populations of Caenorhabditis elegans has been quantitatively and qualitatively analyzed for the presence of 5-methylcytosine. High performance liquid chromatography on two wild-type and several mutant strains of C. elegans failed to detect any 5-methylcytosine. The restriction endonuclease isoschizomers, HpaII and MspI, were used to digest genomic DNA after CsCl purification and failed to detect any 5' cytosine methylation at any age. We conclude that C. elegans does not contain detectable (0.01 mole percent) levels of 5-methylcytosine.

Shi X et al. (2020) Int J Biol Macromol "In vivo approach of simply constructed pyrazinamide conjugated chitosan-g-polycaprolactone micelles for methicillin resistance Staphylococcus aureus."

Sasidharan P, Praphakar RA, Murugan M, Rajan M, Suganya K, Shi X

[Int J Biol Macromol, 2020]

Methicillin-resistant Staphylococcus aureus (MRSA) is an extensive origin of nosocomial infections that are very much challenging as well as complicated to eradicate mostly due to their strong resistance against all existing antibiotic therapies. Here the chitosan-grafted-polycaprolactone/maleic anhydride-pyrazinamide (CS-g-PCL/MA-PZA) polymeric drug carrier constructed via dialysis for anti-MRSA drugs like rifampicin (RF) and pyrazinamide (PZA) delivery. Nearly 200nm size of the spherical particle with -20.04mV of zeta potential observed. The cumulative PZA and RF releases from the carrier were observed 83.25% and 76.54% respectively in pH5.5, and the in vitro drug release profile demonstrates that the fabricated micelle was pH-responsive. For the intestinal colonization, an in vivo assay performed using C. elegans, and the CS-g-PCL/MA-PZA/RF micelles treated worms generally belong to the weakly colonized category. Therefore, the study revealed that CS-g-PCL/MA-PZA/RF micelle could be a promising approach for therapeutic applications to achieve efficient anti-MRSA drug delivery.

Shi P et al. (2020) Drug Deliv "A promising drug delivery candidate (CS-g-PMDA-CYS-fused gold nanoparticles) for inhibition of multidrug-resistant uropathogenic Serratia marcescens."

Amarnath Praphakar R, Rajan M, Ullah R, Murugan M, Deepa S, Shi P, Bari A, Suganya K, Gupta P

[Drug Deliv, 2020]

Antibiotic resistance amongst microbial pathogens is a mounting serious issue in researchers and physicians. Various alternatives to overcome the multidrug-resistant bacterial infections are under search, and biofilm growth inhibition is one of them. In this investigation, a polymeric drug delivery system loaded with multi-serratial drugs to improve the delivery of drugs against urinary tract infection causative <i>Serratia marcescens</i>. The chitosan grafted pyromellitic dianhydride - cysteine (CS-g-PMDA-CYS) was conjugated with AuNPs by using the -SH group of CYS and RF (rifampicin) and INH (isoniazid) were loaded in AuNPs-fused CS-g-PMDA-CYS system. Several physicochemical techniques characterized this fabricated AuNPs/RF/INH/CS-g-PMDA-CYS system. The successful encapsulation of RF and INH in AuNPs-fused CS-g-PMDA-CYS polymer had confirmed, and it observed the loading capacity for RF and INH was 9.02% and 13.12%, respectively. The <i>invitro</i> drug discharge pattern was perceived high in pH 5.5 compared with pH 7.4. The AuNPs/RF/INH/CS-g-PMDA-CYS escalates 74% of <i>Caenorhabditis elegans</i> survival during <i>Serratia marcescens</i> infection by aiming biofilm development and virulence in <i>S. marcescens</i>. Author postulate that the fabricated system is a promising drug carrier and delivery system for inhibition of multidrug-resistant bacterias like <i>S. marcescens</i>.

Yoon CH et al. (1995) International C. elegans Meeting "MOLECULAR CHARACTERIZATION OF SLI-1, A NEGATIVE REGULATOR OF THE LET-23-MEDIATED VULVAL INDUCTION"

Lee JH, Sternberg PW, Jongeward GD, Yoon CH

[International C. elegans Meeting, 1995]

Genetic studies show that sli-1 is a negative regulator of LET-23-mediated signalling: reduction-of-function (rf) mutations in sli-1 suppress let-23(rf) mutations in vulval induction; LET-23 is a C. elegans homolog of the mammalian EGF receptor-tyrosine-kinase. sli-1(rf) suppresses a sem-5(rf) mutation and very weakly suppresses let-60(rf) mutations; SEM-5 is a Grb2-like adaptor and LET-60 is a Ras protein. sli-1's genomic organization consists of 11 exons; a full-length cDNA as well as an alternatively spliced cDNA lacking exon 10 have been identified. The full-length cDNA has an open reading frame encoding a putative product of 582 residues. SLI-1 is similar to the product of c-cbl, a previously novel mammalian proto-oncogene. SLI-1 and c-cbl share ~55 % amino acid identity over a novel stretch of 390 residues, each containing a RING finger, a C3HC4 Zn-binding motif. SLI-1 and c-cbl also have multiple consensus sites for SH3 domain binding. We have sequenced two strong sli-1(rf) alleles: our reference allele, sy143, is an amber mutation that removes C-terminal 74 % of SLI-1; sy129 is a missense mutation in a conserved residue. sli-1's genetic interactions with components of LET-23-mediated signalling pathway and potential for SH3 binding increase the likelihood that SLI-1 has direct physical interactions with proteins associated with LET-23. SLI-1 and c-cbl may define a new class of proteins that modify the activity of tyrosine kinase mediated signal transduction.