Lo, Yun-Hua et al. (2015) International Worm Meeting "Sex-ratio bias in Caenorhabditis."

Yang, Fang-Jung, Le, Son Tho, Wang, John, Hsu, Jung-Chen, Lo, Yun-Hua, Chang, Tiffany

[International Worm Meeting, 2015]

Most sexual species produce nearly equal sex ratios in their offspring. In nematodes, deviations from equal sex ratios occur in the self-fertile hermaphroditic species, which have evolved independently several times. Hermaphrodites produce predominantly hermaphrodite offspring, while sons are rarely observed, consistent with the high theoretical cost of male offspring in these species. In the genus Caenorhabditis, the three known hermaphroditic species also produce occasional males. When crossing occurs in C. elegans, the female-to-male offspring ratio is ~1:1, like most sexual species. In contrast, a previous study demonstrated that C. briggsae has a female-biased sex ratio (~2:1) possibly caused by competition between male X- versus O-bearing sperm.The female-biased sex ratios in C. briggsae may have evolved because of the probable advantages for fathers who produce more daughters, since a solitary hermaphrodite, but not son, can found a population. Alternatively, other conditions, such as local mate competition, may select for female-biased sex ratios. In the first model, only hermaphroditic species should have female-biased sex ratios, while in the second, female/males species could have female-biased sex ratios. To test these two possibilities, we conducted crossing experiments in the third hermaphroditic species, C. tropicalis, as well as 12 female/male species. We found that C. tropicalis produced an offspring sex ratio of ~1:1. For the female/male species, five exhibited ~1:1 ratios while seven others produced female-biased sex ratios. These results suggest that factors other than (or in addition to) hermaphroditism have selected for the evolution of female-biased sex ratios in this clade.

Palikaras, Konstantinos et al. (2021) International Worm Meeting "Mitochondrial defects manifest an early pathogenic event undermining organismal fitness in a Tauopathy model"

Akbari, Mansour, Achanta, Kavya, Bohr, Vilhelm, Palikaras, Konstantinos

[International Worm Meeting, 2021]

Battling age-associated neurodegenerative pathologies and their pervasive societal impact, is a global enterprise. Alzheimer's disease (AD) is the most common dementia affecting elderly population and there is not any efficient therapeutic strategy until now. Age-dependent impairment of mitochondrial homeostasis is a common feature in evolutionary divergent organisms and is associated with neuronal loss and cognitive decline in AD. However, whether mitochondrial dysfunction is a culprit or bystander of AD pathology remain still elusive. Here, we utilized transgenic nematodes expressing the full length of wild type Tau (Tauwt-lo) in neuronal cells and monitored several aspects of mitochondrial morphology. Although Tauwt-lo expressing nematodes do not present Tau aggregates during larval stages, they display increased mitochondrial damaged and locomotion defects. Interestingly, calcium chelating agents restores mitochondrial activity and motility in Tauwt-lo expressing larvae suggesting that cytoplasmic calcium elevation mediates neuronal impairment. Our findings in their totality suggest that mitochondrial damage is an early pathogenic event of AD that is taking place before Tau aggregation undermining neuronal homeostasis and organismal fitness during aging.

Sowa, Jessica et al. (2017) International Worm Meeting "The role of the decapping enzyme EOL-1 in intracellular infection response."

Troemel, Emily, Sowa, Jessica

[International Worm Meeting, 2017]

Microsporidia comprise a phylum of obligate intracellular parasites most closely related to fungi. Although they infect a wide range of animal species and can cause lethal infections in immunocompromised patients, relatively little is known about the mechanisms of host defense against microsporidia. Nematocida parisii is a species of microsporidia that is a natural pathogen of C. elegans. N. parisii infects the C. elegans intestine, causing fusion of intestinal cells and ultimately lethality (Troemel et al, PLoS Biology 2008; Balla et al, Nature Microbiology 2016). Our lab has profiled the C. elegans transcriptional response to N. parisii (Bakowski et al, PLoS Pathogens 2014), with the goal of identifying features of the host response to microsporidia infection. One gene found to be induced by N. parisii infection was eol-1, a de-capping and exonuclease enzyme that has been reported by Yun Zhang's lab to be involved in regulating pathogen-induced aversive olfactory learning (Shen et al, J. Neuroscience 2014). Our RNAseq data shows that eol-1 is strongly up-regulated during N. parisii infection, beginning early at 8 hours post infection. In uninfected worms, we find that EOL-1 is expressed primarily in the spermatheca and URX neurons based on analysis of EOL-1 transcriptional and translational fusions*. Interestingly we find that when worms are exposed to N. parisii, eol-1 expression is induced in the intestine, which is the tissue targeted by N. parisii. Our preliminary results from analysis of eol-1 mutants suggest that eol-1 plays a role in host response to N. parisii infection. *Thanks to Yun Zhang's lab for sending eol-1 strains.

Semnani RT et al. (2010) J Immunol "Expanded numbers of circulating myeloid dendritic cells in patent human filarial infection reflect lower CCR1 expression."

Traore SF, Sanogo D, Coulibaly SY, Semnani RT, Konate S, Soumaoro L, Diallo AA, Klion A, Dembele B, Mahanty S, Nutman TB, Coulibaly ME, Seriba Doumbia S, Mahapatra L, Metenou S, Dolo H

[J Immunol, 2010]

APC dysfunction has been postulated to mediate some of the parasite-specific T cell unresponsiveness seen in patent filarial infection. We have shown that live microfilariae of Brugia malayi induce caspase-dependent apoptosis in human monocyte-derived dendritic cells (DCs) in vitro. This study addresses whether apoptosis observed in vitro extends to patent filarial infections in humans and is reflected in the number of circulating myeloid DCs (mDCs; CD11c(-)CD123(lo)) in peripheral blood of infected microfilaremic individuals. Utilizing flow cytometry to identify DC subpopulations (mDCs and plasmacytoid DCs [pDCs]) based on expression of CD11c and CD123, we found a significant increase in numbers of circulating mDCs (CD11c(+)CD123(lo)) in filaria-infected individuals compared with uninfected controls from the same filaria-endemic region of Mali. Total numbers of pDCs, monocytes, and lymphocytes did not differ between the two groups. To investigate potential causes of differences in mDC numbers between the two groups, we assessed chemokine receptor expression on mDCs. Our data indicate that filaria-infected individuals had a lower percentage of circulating CCR1(+) mDCs and a higher percentage of circulating CCR5(+) mDCs and pDCs. Finally, live microfilariae of B. malayi were able to downregulate cell-surface expression of CCR1 on monocyte-derived DCs and diminish their calcium flux in response to stimulation by a CCR1 ligand. These findings suggest that microfilaria are capable of altering mDC migration through downregulation of expression of some chemokine receptors and their signaling functions. These observations have major implications for regulation of immune responses to these long-lived parasites.

Manser J (1991) International C. elegans Meeting "mig-10: IN OR OUT?"

Manser J

[International C. elegans Meeting, 1991]

mig-l O III mutants exhibit partially defective embryonic migration of CAN, ALM and HSN neurons and have shortened posterior excretory canals (pec's). Genetic mosaic analysis suggests that mig-lO(+) activity within the excretory cell is neither necessary nor sufficient to effect normal pec outgrowth. Thus, mig-10 may encode a cell- extrinsic component involved in cell movement. Patterns of mosaic Dp loss are consistent with a hypodermal focus, although certain other tissues have not been ruled out. Because the cells whose movements are affected in mig-10 mutants develop in contact with the body wall, a hypodermal focus would not be surprising. mig-l O has been cloned by transformation rescue. Germline microiniection of either of two overlapping cosmid clones, FlOE9 or F49A3, can completely rescue mig-l O(ct41 ) phenotypes. Both cosmids have been used as probes to isolate a set of at least 22 genomic lambda phage clones containing sequences from the overlap. The lambdas are currently being used in transformation rescue experiments designed to narrow mig-10 to a physical interval of manageable size for molecular analysis.

Bakaev VV et al. (1998) Worm Breeder's Gazette "AN ATTEMPT TO SLOW AGING IN C. elegans. 9. NO POSITIVE EFFECT OF EPITHALAMIN"

Bakaev VV, Efremov AV, Anisimov VN

[Worm Breeder's Gazette, 1998]

There are data on the life span prolonging effect of pineal peptide preparation epithalamin in mice, rats and Drosophila melanogaster [1,2]. The purpose of this study was to investigate the effect of different concentrations of epithalamin in water solutions on nematode life span. In this experiment epithalamin was used in following dilutions 1:10*5, 1:10*6, 1:10*7, 1:10*8, 1:lO*9 and 1:10*10. Three adult animals (3 - 5 days old) were kept in microtitre wells containing 0.75 ml of liquid medium (with E. coli and without epithalamin) during 4 hours, then they were discarded and newborn larvae were transferred in next wells (with epitalamin in any concentration) every day (one worm in one well). This investigation was carried out in temperature +21C and in the darkness. The obtained results are presented in the following table. Table I Concentration of Longevity (days) epithalamin n mean +/- S.E. maximal Control 12 17.4 +/- 2.5 29 1:10*5 12 12.8 +/- 2.1 27 1:10*6 12 15.1 +/- 1.9 28 1:10*7 12 17.1 +/- 2.2 28 1:10*8 12 19.6 +/- 2.2 29 1:10*9 12 18.8 +/- 2.0 31 1:10*10 12 18.7 +/- 1.7 25

Land M et al. (1994) J Biol Chem "Structure and expression of a novel, neuronal protein kinase C (PKC1B) from Caenorhabditis elegans. PKC1B is expressed selectively in neurons that receive, transmit, and process environmental signals."

Land M, Rubin CS, Freedman JH, Islas-Trejo A

[J Biol Chem, 1994]

The nematode Caenorhabditis elegans provides an advantageous system for investigating the regulation, expression, and functions of protein kinase C (PKC) isoforms. We cloned and characterized cDNAs encoding a novel C. elegans PKC designated PKC1B. The predicted PKC1B polypeptide contains features characteristic of the nPKC subfamily of PKC isoforms. The levels of PKC1B and its cognate mRNA vary over a 7-fold range during C. elegans postembryonic development. PKC1B protein and mRNA are abundant at the earliest larval stage, but their relative concentrations decrease coordinately in late larvae. Embryos, which are enriched in PKC1B mRNA, contain little PKC1B protein. Thus, PKC1B expression is regulated at a translational or post-translational level during early development. Cells engaged in PKC1B gene transcription were identified in transgenic C. elegans that carry the lacZ gene under the regulation of the PKC1B promoter. Staining for beta galactosidase revealed PKC1B promoter activity exclusively in sensory neurons and interneurons. Immunofluorescence microscopy disclosed that the PKC1B polypeptide is located in the processes (axons and dendrites) and perinuclear regions of similar to 75 neurons that constitute the sensory circuitry of the nematode. The intracellular lo calization of PKC1B and the enzyme's differential solubility in ionic and nonionic detergents suggest that the kinase is associated with membranes and

Merlet, Jorge et al. (2010) C. elegans: Development and Gene Expression, EMBL, Heidelberg, Germany "The CRL2LRR-1 ubiquitin-ligase regulates cell cycle progression during C. elegans development"

Merlet, Jorge, Gomes, Jose-Eduardo, Tavernier, Nicolas, Pintard, Lionel, Burger, Julien, Richaudeau, Benedicte

[C. elegans: Development and Gene Expression, EMBL, Heidelberg, Germany, 2010]

In early C. elegans embryos, the ATR (ataxia telangectasia mutated and rad3 related) checkpoint pathway controls the timing of cell division in the P lineage, or future germ line of the animal. However, the mechanisms regulating the ATR checkpoint pathway are still poorly understood. Here, we establish that the Leucine Rich Repeats protein, LRR-1, promotes cell cycle progression during development in C. elegans , both in the adult germ line and in the early embryo. Our results indicate that LRR-1 is a substrate-recruitment factor of a cullin 2-RING E3-ligase (CRL2), which down regulates the ATR signaling pathway in C. elegans . LRR-1 contains a typical BC/Cul2-box through which it binds CRL2 components in vitro and in vivo . Lo ss of lrr-1 function causes a cell-cycle arrest in the mitotic region of the germ line resulting in sterility owing to depletion of germ cells. Inactivation of the DNA replication checkpoint signaling components ATR/ATL-1 and Chk1/CHK-1 suppresses this cell cycle arrest and fully restores lrr-1 mutant fertility. Likewise, in early embryos, lrr-1 inactivation leads to hyper-activation of the ATL-1/Chk1 pathway, which delays mitotic entry and causes embryonic lethality. Our findings suggest a model in which the CRL2 LRR-1 E3 ligase negatively regulates the DNA replication checkpoint and thereby coordinates cell cycle progression and development.

Kenney SJ et al. (2004) J Food Prot "Effectiveness of cleaners and sanitizers in killing Salmonella Newport in the gut of a free-living nematode, Caenorhabditis elegans."

Williams PL, Anderson GL, Millner PD, Beuchat LR, Kenney SJ

[J Food Prot, 2004]

Caenorhabditis elegans, a free-living nematode found in soil, has been shown to ingest human enteric pathogens, thereby potentially serving as a vector for preharvest contamination of fruits and vegetables. A study was undertaken to evaluate the efficacy of cleaners and sanitizers in killing Salmonella enterica serotype Newport in the gut of C. elegans. Adult worms were fed nalidixic acid-adapted cells of Escherichia coli OP50 (control) or Salmonella Newport for 24 h, washed, placed on paper discs, and incubated at temperatures of 4 or 20 degrees C and relative humidities of 33 or 98% for 24 h. Two commercial cleaners (Enforce and K Foam Lo) and four sanitizers (2% acetic acid, 2% lactic acid, Sanova, and chlorine [50 and 200 microg/ml]) were applied to worms for 0, 2, or 10 min. Populations of E. coli and Salmonella Newport (CFU per worm) in untreated and treated worms were determined by sonicating worms in 0.1% peptone and surface plating suspensions of released cells on tryptic soy agar containing nalidixic acid. Populations of Salmonella Newport in worms exposed to 33 or 98% relative humidity at 4 degrees or 33% relative humidity at 20 degrees C were significantly (P < or = 0.05) lower than the number surviving exposure to 98% relative humidity at 20 degrees C. In general, treatment of desiccated worms with cleaners and sanitizers was effective in significantly (P < or = 0.05) reducing the number of ingested Salmonella Newport. Results indicate that temperature and relative humidity influence the survival of Salmonella Newport in the gut of C. elegans, and cleaners and sanitizers may not eliminate the pathogen.

Hubbard EJA et al. (2000) East Coast Worm Meeting "Characterization of proximal proliferation (Pro) mutants"

Hubbard EJA, Pepper A

[East Coast Worm Meeting, 2000]

In many organisms, undifferentiated germ cells proliferate prior to entering meiosis, but the factors that govern the temporal and spatial aspects of the earliest meiotic entry events are not well understood. We are using proximal proliferation mutants in C. elegans as an entry point to investigate these factors. Genetic screens in our lab have identified mutants that display a "proximal proliferation" (Pro) germline phenotype but do not appear to affect somatic gonad development. In Pro mutants, instead of the normal adult distal-to-proximal germline pattern of "mitosis, meiosis, gametogenesis", a pattern of "mitosis, meiosis, gametogenesis, mitosis" is observed. Therefore these mutants contain an ectopic region of proliferating cells in the proximal region of the gonad (proximal to mature gametes), yet maintain their ability to adopt normal germ cell fates. Normally, the proximal-most cells are the first cells to enter meiosis in the L3. Therefore, the Pro phenotype could arise from a disruption in mechanisms that control the spatial and/or temporal regulation of the proximal mitosis/meiosis switch in the L3. In this model, the Pro phenotype results from abnormal proliferation of proximal-most germ cells, while more distal germ cells undergo normal differentiation. Three of our Pro mutants proved to be glp-1 alleles (see abstract by Lo and Hubbard). Several other mutations were identified that cause a similar Pro phenotype but are not glp-1 alleles. These mutations likely identify genes involved in the regulation of the spatial or temporal patterning of meiotic entry. We are in the process of characterizing the non-glp-1 Pro mutants genetically, phenotypically and molecularly to determine their role in patterning of meiotic entry. Two-factor, three-factor and deficiency mapping are being used to refine the map positions of the Pro alleles. Recent results indicate that one of the alleles maps within a defined region of chromosome II, while another maps to the X chromosome. Further progress on characterization of these alleles will be presented at the meeting.