White C et al. (2009) Mol Cell Biochem "The DNA damage-inducible C. elegans tankyrase is a nuclear protein closely linked to chromosomes."

St-Laurent JF, White C, Desnoyers S, Gravel C, Gagnon SN, Proulx LI

[Mol Cell Biochem, 2009]

Tankyrases are protein members of the poly(ADP-ribose) polymerase family bearing several ankyrin domain and a WGR domain. They have functional role in telomere maintenance, are found at centrosome, and are associated with vesicular secretion. This diversity in localization and function makes it difficult to identify a unified role for tankyrases. We have shown that the C. elegans orthologue PME-5 is among the most transcriptionally up-regulated genes following ionizing radiations, linking a tankyrase with DNA damage response. Our analysis showed that the up-regulation of PME-5 is translated at the protein level, suggesting an effective role in DNA damage response or DNA repair. In order to gain more information on the potential role of PME-5 in DNA damage response, we analyzed its sub-cellular localization. Using immunostaining as well as gfp reporter assay, we have shown a nuclear localization for PME-5. Moreover, we showed that PME-5 is a ubiquitous nuclear protein expressed throughout the development of the worm and is closely linked to chromatin and condensed chromosomes. Taken together, our data suggest that C. elegans can be used to study the nuclear roles of tankyrase.

White JG et al. (1981) International C. elegans Meeting "the nervous system of C elegans."

Thomson JN, Southgate E, White JG

[International C. elegans Meeting, 1981]

White JG et al. (1983) International C. elegans Meeting "the nervous system of C elegans."

Southgate E, Brenner S, Thomson JN, White JG

[International C. elegans Meeting, 1983]

White JG et al. (1991) International C. elegans Meeting "THE STRUCTURE OF THE L4 HERMAPHRODITE GONAD."

White JG, Southgate E, Kershaw D

[International C. elegans Meeting, 1991]

We have been reconstructing the hermaphrodite gonad from electron micrographs of serial sections. This structure has a two-fold axis of symmetry centred about the vulva. There are 8 distinct regions in the somatic gonad: the connection to the vulva, the connection to the seam cells, the uterus, the spermathecal valve, the spermatheca, the oviduct, the ovary sheath and the distal tip. Starting at the vulva there are a group of three sets of two mononucleate cells (uv1-3) that form the connection of the uterus to the vulva; there is also a single dorsal uterine cell (du) with four nuclei opposite the ventral vulval/uterine junction in this region. The uterus is attached to the seam cells laterally in the vicinity of the vulva by a single 'H' shaped cell containing 9 nuclei (use). Next there is a sequence of four multinucleate toroidal uterine cells (ut1-4); these are followed by a toroidal spermathecal valve cell containing four nuclei which has a ring of microfilaments that wrap around the inside face of the torus and presumably acts as a sphincter to close the valve in the adult. The lumen of the valve cell is blocked by a bi-nucleate plug cell in the L4; presumably this gets expelled from the gonad when eggs pass through the spermathecal valve. Distal to the spermathecal valve are the cells of the spermatheca. In the L4 these are organised as an extended tube made up of 28 individual, mononuclate cells. In the proximal regions these cells are arranged as four cells surrounding the central lumen, whereas there are only two cells surrounding the lumen in more distal regions. The spermathecal cells are connected by characteristic electron dense junctions and seem to be in the process of telescoping together in the L4 to form the more compact adult structure. The oviduct is made up of two sets of two mononuclear cells which contain prominent assemblies of myofilaments. This structure is highly motile and seems to be used for picking an oocyte from the syncytial mass of germ cells and delivering it to the spermatheca where it is fertilised. Distal to the oviduct is a single binucleate toroidal cell that surrounds the germ cells. In the L4s these are primary spermatocytes. The gonad no longer has a continuous sheath of somatic cells beyond this region. It is, however, partially ensheathed by 6 cells and completely surrounded by a basal lamina. The distal tip cell, as its name implies, is situated at the distal extremity of each arm of the gonad. We hope that a more detailed appreciation of the anatomical organisation of the gonad will enable a more precise description of the phenotype of sterile or intersexual mutations to be made and thereby facilitate studies of the genetic basis of organogenesis.

White JG et al. (1991) International C. elegans Meeting "ULTRASTRUCTURAL STUDIES OF THE DEVELOPING VULVA"

White JG, Kershaw D, Southgate E

[International C. elegans Meeting, 1991]

The L4 vulval primordium consists of a tube made up of a stack of seven toroidal, multinucleate epithelial cells. We have been studying the developmental events that lead to the generation of this organ from the three progenitor ventral epithelial cells. The seven vulval cells have been designated A, B1, B2, C, D, E & F. Cell A is attached to the syncytial hypodermis (hyp-7) and F is attached to the the uv1 cells of the uterus. In addition, E is attached to the seam cells laterally. Vulval cells are polarised such that their apical surfaces are situated at the inside of the toroid. Belt desmosomes are seen at the attachment points between adjacent cells and demarcate the apical from the basolateral domain within a cell. The ventral epithelial cells of the vulval equivalence group that do not normally contribute to the vulva (i.e. P3p, P4p & P8p) fuse soon after they divide (indeed, in one reconstruction, P4pa & P4pp had fused before P6p had completed cell division). Interactions from the anchor cell designate P5p, P6p and P7p as vulval precursors and these cells undergo two rounds of division without any overt signs of differentiation. At this stage the vulval primordium consists of a linear sequence of 12 epithelial cells and has started to buckle inwards. The first sign of organogenesis occurs when P6ppp and P6paa divide transversely. The daughters of these two divisions move ventrally and laterally towards the centre line of the vulva where they connect to form a ring of cells. When the ring has formed it appears as if it contracts forming an internal mound which enlarges dorsally. We are currently reconstructing a later stage, lineaged animal which should reveal how the other toroids are formed and how the connection with the uterus is made.

Jamie White et al. (2001) International C. elegans Meeting "A reverse genetic approach to neuropeptide function in the ASH sensory circuit"

Jamie White, Anne Hart

[International C. elegans Meeting, 2001]

Backward locomotion in response to nose touch, 1-octanol, benzaldehyde, and high osmolarity is mediated by the ASH sensory neurons (CGC 1705, 2314). Glutamate neurotransmission between ASH and the interneurons of the ASH circuit appears to be absolutely required, since the response to all stimuli is abolished by a mutation in EAT-4, a sodium-dependent P i cotransporter proposed to load glutamate into synaptic vesicles (CGC 3349, PMID 11001057). However, a mutation in the GLR-1 glutamate receptor subunit eliminates the response to only nose touch (PMID 7477294). GLR-1 functions post-synaptically, in the interneurons of the ASH circuit, not in detection in ASH itself, indicating that glutamatergic neurotransmission is modulated in a stimulus-specific manner (PMID 7477294). That is, glutamatergic neurotransmission is necessary but not sufficient for the response to volatile odorants and high osmolarity. To understand how the ASH circuit transmits stimulus-specific information across the ASH-interneuron synapse, we are investigating the function of novel neuropeptides in the ASH circuit. There are at least 32 neuropeptide-like preprotein ( nlp ) genes in the genome, and GFP-reporter studies show at least two of these are expressed in ASH (ECWM 2000ab56). Additionally, electron microscopy has shown dense-core vesicles, presumably containing peptidergic transmitters or modulators, at the ASH-interneuron synapse (PMID 8806). These observations raise the possibility that NLP peptides could modulate glutamate neurotransmission in a stimulus-specific manner. To address the function of putative ASH-specific neuropeptides, we generated a frozen deletion library of 2.4x10 6 genomes, and are currently screening for deletions in the putative neuropeptide genes. Results of the deletion screening and preliminary phenotypic analysis will be presented.

White JG et al. (1977) International C. elegans Meeting "the anterior nervous system of C elegans."

Southgate E, Brenner S, Thomson JN, White JG

[International C. elegans Meeting, 1977]

White JG et al. (1985) International C. elegans Meeting "friends and neighbors in the C elegans nervous system."

White JG, Southgate E, Brenner S, Thomson JN

[International C. elegans Meeting, 1985]

White JG et al. (1989) International C. elegans Meeting "anatomical changes in the ventral cord of mutants of unc-30."

Thomson JN, Southgate E, White JG

[International C. elegans Meeting, 1989]

White JG et al. (1993) International C. elegans Meeting "EM reconstructions of the gonads of developing muv mutants."

Southgate E, Kershaw D, White JG

[International C. elegans Meeting, 1993]