Chung M. Chan et al. (2008) "The cellular and molecular components for sex pheromone perception in Caenorhabditis."

King L. Chow, Queenie W.K. So, Chung M. Chan, Mei Y. Wu

[2008]

"Finding a mating partner in a dioecious species is an obligatory process for species survival. In previous study, we have used C. remanei and C. elegans as the model to demonstrate that only females of the dioecious species can produce a volatile and stable sex pheromone to effectively attract males. Males from both dioecious and androdioecious species respond to this same sex pheromone with C. remanei males displaying a stronger attractive response. In this study, we focus our investigation on the following aspects: to identify the cellular and molecular components for sex pheromone perception in Caenorhabditis males; and to examine whether the difference in the response to sex pheromone among males and females/hermaphrodites is due to the presence of sex-specific neurons or the sexual identity of neural circuitry. The perception of sex pheromone by androdioecious C. elegans males and the availability of genetic mutants with defective cell fate or molecular function allow us to delineate the cellular and molecular components required for pheromone perception. Together with confirmation by laser ablation, two different sensory neurons (AWA, CEM) and an interneuron (AIZ) are shown to be required for this perception. A signaling pathway dependant of G-protein coupled kinase activity and G-protein subunit are crucial for this chemosensory response. The process may act through the gating of channels in specific neurons. The evaluation of the function of these molecules in specific neurons through cell-specific expression and cell-specific knock-down will be presented. Although males and hermaphrodites respond to the same olfactory attractants, other research have shown that each sex has different olfactory preferences, and it has been shown that the difference is due to the sexual identity of the core neural circuitry. In this report, we would further investigate the effect of sexual identity of the core neural circuitry and specific cell types on sex pheromone perception by genetic masculinization of neurons in hermaphrodites. (This study is funded by the Research Grants Council, Hong Kong.)"

Chung-Man Chan et al. (2007) International Worm Meeting "Perception of sex pheromone in Caenorhabditis: identification of cellular and molecular components in the signal relay."

King L. Chow, Chung-Man Chan, Queenie W.K. So, Mei-Yee Wu

[International Worm Meeting, 2007]

Finding a mating partner in a dioecious species is an obligatory process for species survival. We have used C. remanei and C. elegans as models to show that only females of the dioecious species can produce a volatile and stable sex pheromone to effectively attract males. On the other hand, males from both dioecious and androdioecious species respond to this same pheromone with the C. remanei males displaying a stronger attractive response. In this report, we focus our investigation on three specific issues; where is the sex pheromone produced? How is its production physiologically controlled, and how do males perceive the sex pheromone? Pheromone has been reported to be produced by a variety of tissues. To ascertain if gonadal tissues are required for its production, laser ablation was used to eliminate different combination of the gonadal precursor cells. Our results confirm that the somatic gonad is required for the production of this pheromone. The pheromone production peaks at the young adult stage, and mating with males would eliminate the attractiveness of a female. We showed that mating itself and the presence of sperms in the female body would not eliminate the pheromone attractiveness. The mechanism of mating on the attenuation of attractiveness will be discussed in light of a systematic analysis of the male gonad requirement. While the perception of the pheromone by androdioecious C. elegans males allows us to delineate molecularly and cellularly using genetic mutants with defective cell fate or molecular function. Two different sensory neurons and an interneuron are shown to be required for this perception. A signaling pathway dependant of G-protein coupled kinase activity and G-protein subunit are crucial for this chemosensory response. The process may act through the gating of channels in specific neurons. The evaluation of the function of these molecules in specific neurons will be presented. (This study is funded by the Research Grants Council, Hong Kong.).

Kei-Chu Fan et al. (2008) "Sex pheromone perception in Caenorhabditis is modulated by the insulin-like signaling pathway."

King L. Chow, Chung-Man Chan, Queenie W.K. So, Kei-Chu Fan

[2008]

"Sex pheromone is a volatile chemical released by C. remanei females, used to attract males for mating. The response to sex pheromone is sex- and stage-specific. Only adult males are attracted. This response, however, is not species-specific; males of the other Caenorhabditis species are also attracted by this pheromone. In our study, we use C. elegans, which can be attracted by the sex pheromone and has a rich collection of mutants with defective sensory circuit, as a model organism to investigate what are required for the males to execute their pheromone response. Males of its mutants will be tested in the chemoattraction assay for the Chemoattraction Index. C.I. value ranges from -1 to 1 where a higher value indicates a stronger response. As a result, males of a C. elegans mutants having C.I. value lower than that of wildtype C. elegans males implicate genes required for sex pheromone perception.In C. elegans, the insulin-like signaling pathway coordinates multiple biological functions such as mediating the choice of dauer formation, affecting the rate of aging and searching of food. These activities are elicited by various chemical inputs like the dauer pheromone, signals from the gonad and food. Recent studies also suggested that this pathway affects the mate searching ability in C. elegans males (Lipton et al., 2004). It is possible that cross talks among cells involved in sex pheromone perception exist. Base on this speculation, mutants of gene involved in the daf-2/daf-16 insulin-like signaling pathway were tested in the chemoattraction assay for their response to sex pheromone. Among them, several mutants have their C.I. values dramatically reduced. These genes encode various receptor components and signaling molecules like phosphoinositide 3-kinase (PI3K) and serine/threonine kinase (Akt/PKB) in the daf-2/daf-16 insulin-like signaling pathway. In this report, more detailed experiments substantiating the involvement of insulin-like signaling pathway in sex pheromone perception will be discussed. (This study is funded by the Research Grants Council, Hong Kong.)"

Crombie C et al. (2003) Genome Biol "The not-so-humble worm."

Fraser A, Crombie C, Junio A

[Genome Biol, 2003]

A report of the Wellcome Trust meeting "Caenorhabditis elegans past, present and future: The not-so-humble worm", Hinxton, UK, 10 September 2003.

Thierry-Mieg D et al. (1996) Worm Breeder's Gazette "ACE.MBLY, a graphic program for wild type and mutant sequence assembly"

Sauvage U, Thierry-Mieg D, Thierry-Mieg J

[Worm Breeder's Gazette, 1996]

A rapidly expanding portion of the sequence of the wild type is now available. So, many laboratories face the problem of sequencing their pet alleles, looking for mutations.

Van Hoffelen S et al. (2006) Curr Biol "Stem cells: specifying stem-cell niches in the worm."

Van Hoffelen S, Herman MA

[Curr Biol, 2006]

Recent work has shown that components of the Wnt signaling pathway directly activate a homeodomain transcription factor so as to specify the cell fate that provides niche function to germline stem cells in the nematode Caenorhabditis elegans.

Bargmann C et al. (2002) Cell "Accolade for elegans."

Hodgkin J, Bargmann C

[Cell, 2002]

In 1963, Sydney Brenner, one of the founders of molecular biology, had reached an intellectual impasse. He felt that there were few advances left in that field that would have the significance of the discovery of mRNA and the elucidation of the genetic code, both of which he had participated in, and in any case with so many Americans joining in, the chemical details of replication and so forth would all be worked out soon. Brenner thought large thoughts, and the questions that were left seemed too

Portman DS (2024) Curr Biol "Behavioral evolution: No sex please, we're hermaphrodites."

Portman DS

[Curr Biol, 2024]

Many 'hard-wired', innate animal behaviors are related to reproduction. So what happens when reproductive systems evolve? New research in nematodes has identified principles underlying the co-evolution of reproductive strategy and sexual behavior, revealing some surprises and raising intriguing new questions.

Sulston JE (2003) Chembiochem "Caenorhabditis elegans: the cell lineage and beyond (Nobel lecture)."

Sulston JE

[Chembiochem, 2003]

Thank you so very much for inviting me to be here. It gives me a mingled sense of humility at how much I owe to others, and of joy that the collective work on the worm has been recognised in this way.

Sulston JE (2003) Biosci Rep "C. elegans: the cell lineage and beyond."

Sulston JE

[Biosci Rep, 2003]

Thank you so very much for inviting me to be here. It gives me a mingled sense of humility at how much I owe to others, and of joy that the collective work on the worm has been recognized in this way.