Casson LP et al. (1986) Worm Breeder's Gazette "effects of duplicating X-linked genes on the general expression of the Xchromosome."

Meyer BJ, Casson LP

[Worm Breeder's Gazette, 1986]

mnDp10 is a large duplication of the right side of X, covering the myo-2 gene. Northern assays indicate that an XX hermaphrodite carrying two copies of mnDp10 accumulates twice as much myo-2 mRNA as a wild-type hermaphrodite. This observation indicates that expression of the myo-2 gene is in proportion to its copy number, an important control for our dosage compensation experiments. In examining three other X-linked loci not covered by this duplication, we discovered that the two dosage compensated loci, uxt-1 (adjacent to sup-7) and uvt-4 (adjacent to the vit genes) are also affected by this duplication. The levels of uxt-1 and uvt-4 mRNA are twice as high in the duplication strain as in a wildtype hermaphrodite strain. However, act-4 expression remains unchanged by mnDp10. (Expression of uxt-1 and uvt-4 is elevated in dpy-21, dpy27, dpy-28, and egl-16 strains whereas expression of act-4 is not). We are currently investigating the relevance of these observations to the mechanism of dosage compensation. (Phil Meneely has observed a similar phenomenon: lin-15 hypomorphs are suppressed by X duplications not covering this locus.)

Guo X et al. (2024) Int J Biol Macromol "Antioxidant and anti-aging activities of Longan crude and purified polysaccharide (LP-A) in nematode Caenorhabditis elegans."

She G, Wei P, Xin Q, Su Z, Yuan R, Zhang Y, Guo X, Hua Y

[Int J Biol Macromol, 2024]

Oxidative damage is an important cause of aging. The antioxidant and anti-aging activities of Longan polysaccharides, especially purified Longan polysaccharides, have not been thoroughly investigated. Therefore, this study aimed to investigate the antioxidant and anti-aging activities and mechanisms of crude polysaccharides and purified polysaccharides from Longan. A purified acidic Longan polysaccharide LP-A was separated from Longan crude polysaccharide LP. Subsequently, its structural characterization, anti-aging activity and mechanism were studied. The results showed that LP-A was an acidic heteropolysaccharide with an average molecular weight (Mw) of 4.606 × 10⁴ Da which was composed of nine monosaccharides. The scavenging rate of ABTS free radical in vitro reached 99 %. In the nematode life experiment, 0.3 mg/mL LP group and LP-A group could prolong the average lifespan of nematodes by 9.31 % and 25.80 %, respectively. Under oxidative stress stimulation, LP-A group could prolong the survival time of nematodes by 69.57 %. In terms of mechanism, Longan polysaccharide can regulate insulin / insulin-like growth factor (IIS) signaling pathway, increase the activity of antioxidant enzymes, reduce lipid peroxidation, enhance the body's resistance to stress damage, and effectively prolong the lifespan of nematodes. In conclusion, LP-A has better anti-aging activity than crude polysaccharide LP, which has great potential for developing as an anti-aging drug.

Meyer BJ et al. (1985) Worm Breeder's Gazette "more about dosage compensation."

Meyer BJ, Casson LP

[Worm Breeder's Gazette, 1985]

In response to appreciated criticism at the Cold Spring Harbor worm meeting, we have extended our biochemical analysis of dosage compensation to control for possible complications caused by differences in anatomy and hence gene expression in males and hermaphrodites. We have measured the relative transcript levels of the two myosin genes (myo-1(I), expressed in the pharynx, a tissue which is nearly identical in males and hermaphrodites. (We made gene-specific probes from clones of myo-1 and myo-2 obtained from J. Karn.) Transcript levels for myo-2 were found to be identical in X0 males and XX hermaphrodites when normalized to the levels of myo-1. In addition the level of myo-2 in hermaphrodites bearing a mutation in either dpy-21, ted by 2-3 fold compared to the level of myo-2 in wild-type hermaphrodites (when normalized to myo-1). This set of observations is in agreement with those we presented at the meeting using act-1, omal probes and other X-specific probes. In our assays act-4(X) behaves differently from other X-specific genes in that the level of act-4 is not elevated in dpy-21, odites although the level in males and hermaphrodites appears to be identical (when normalized to act-1,

Meyer BJ et al. (1986) Cell "Caenorhabditis elegans compensates for the difference in X chromosome dosage between the sexes by regulating transcript levels."

Casson LP, Meyer BJ

[Cell, 1986]

The primary sex-determining signal in the nematode C. elegans is the ratio of X chromosomes to sets of autosomes (X/A ratio). As a consequence, males (XO; ratio 0.5) and hermaphrodites (XX; ratio 1.0) possess different doses of X-linked genes. Here we demonstrate that C. elegans compensates for this disparity in gene dose by equalizing the levels of X-specific mRNA transcripts in the two sexes. Moreover, we show that mutations in three autosomal genes disrupt the process of dosage compensation. Reduction in the activity of either dpy-21, dpy-27, or dpy-28 results in the overexpression of X-specific genes, 2- to 3-fold above wild-type levels.

TY1807

Caenorhabditis elegans

Huang T et al. (2022) Ann Clin Microbiol Antimicrob "A novel antibiotic combination of linezolid and polymyxin B octapeptide PBOP against clinical Pseudomonas aeruginosa strains."

Zhao K, Liu C, Zeng M, Huang T, Fu H, Prithiviraj B, Chu Y, Zhou J, Zhai L, Guo Y, Wang X, Song T

[Ann Clin Microbiol Antimicrob, 2022]

BACKGROUND: Antibiotic-resistant Gram-negative bacteria are becoming a major public health threat such as the important opportunistic pathogen Pseudomonas aeruginosa (P. aeruginosa). The present study investigated enhancement of the linezolid spectrum, which is normally used to treat Gram-positive bacteria, at inhibiting P. aeruginosa growth. METHODS: The checkerboard test or time-kill assay were carried out to determine the antibacterial effects of linezolid in cooperation with polymyxin B octapeptide PBOP (LP) against P. aeruginosa based on in vitro model. The protective effect of LP against P. aeruginosa infection was assessed based on a Caenorhabditis elegans (C. elegans) model. RESULTS: The synergistic activity and antibacterial effects were significantly increased against P. aeruginosa by LP treatment, while linezolid and PBOP as monotherapies exhibited no remarkably bactericidal activity against the clinical strains. Additionally, LP treatment modified biofilm production, morphology, swimming motility of P. aeruginosa, and protected C. elegans from P. aeruginosa infection. CONCLUSIONS: This research demonstrates that LP combination has significant synergistic activity against P. aeruginosa, and PBOP is potential to be an activity enhancer. Notably, this strategy improved the antibacterial activity spectrum of linezolid and other anti-Gram-positive agents and represents an effective choice to surmount the antibiotic resistance of bacteria in the long term.

TY525

Caenorhabditis elegans

DeLong L et al. (1987) Genetics "Assessment of X chromosome dosage compensation in Caenorhabditis elegans by phenotypic analysis of lin-14."

DeLong L, Meyer BJ, Casson LP

[Genetics, 1987]

Caenorhabditis elegans compensates for the difference in X chromosome gene dose between males (XO) and hermaphrodites (XX) through a mechanism that equalizes the levels of X-specific mRNA transcripts between the two sexes. We have devised a sensitive and quantitative genetic assay to measure perturbations in X chromosome gene expression caused by mutations that affect this process of dosage compensation. The assay is based on quantitating the precocious alae phenotype caused by a mutation that reduces but does not eliminate the function of the X-linked gene lin-14. We demonstrate that in diploid animals the lin-14 gene is dosage compensated, implying that the normal dosage compensation mechanism in C. elegans lacks the capacity to compensate completely for the additional X chromosome in triplo-X animals. Using the lin-14 assay we compare the effects of mutations in the genes dpy-21, dpy-26, dpy-27, dpy-28, and dpy-22 on X-linked gene expression. Additionally, in the case of dpy-21 we correlate the change in phenotypic expression of lin-14 with a corresponding change in the lin-14 mRNA transcript level.

Plenefisch JD et al. (1987) Worm Breeder's Gazette "the lethal phenotype and temperature sensitivity of dpy-27 and dpy-28."

Meyer BJ, Plenefisch JD

[Worm Breeder's Gazette, 1987]

Mutations in dpy-27 and dpy-28 affect the viability of XX but not XO animals. In addition, these mutations disrupt dosage compensation resulting in XX but not XO animals over-expressing their X-linked genes (as assayed by Northern analysis [Meyer and Casson, Cell 47:871 1986] and by morphogenetic assay [DeLong, et al. Genetics, in press]).

Miller LM et al. (1988) Cell "xol-1: a gene that controls the male modes of both sex determination and X chromosome dosage compensation in C. elegans."

Meyer BJ, Plenefisch JD, Casson LP, Miller LM

[Cell, 1988]

Loss-of-function mutations in the X-linked gene xol-1 cause the feminization and death of XO animals (normally males) by shifting the sex determination and dosage compensation pathways toward their hermaphrodite modes. XO-specific lethality most likely results from the reduction in X chromosome expression caused by xol-1 mutations. Mutations in genes required for the hermaphrodite mode of dosage compensation suppress lethality but not feminization, and restore X chromosome expression to nearly wild-type levels. Mutations in genes that control the hermaphrodite modes of both sex determination and dosage compensation fully suppress both defects. These interactions suggest that xol-1 is the earliest-acting gene in the known hierarchy controlling the male/hermaphrodite decision and is perhaps the gene nearest the primary sex-determining signal. We propose that the wild- type xol-1 gene product promotes male development by ensuring that genes (or gene products) directing hermaphrodite sex determination and dosage compensation are inactive in XO animals. Interestingly, in addition to feminizing XO animals, xol-1 mutations further masculinize XX animals already partially masculinized.