Larvae, dauer

Dauer larva Lateral hypodermis, SM, VPC, intestinal cells... 

Lehner CF, Lane ME 1997 Cell cycle regulators in Drosophila-, downstream and part of developmental decisions. J Cell Sci 110 523-528 Liu Z, Ambros V 1989 Heterochronic genes control the stage-specific initiation and expression of the dauer larva developmental program in Caenorhabditis elegans. Genes Dev 3 2039-2049... 

Riddle, D.L. (1988) The dauer larva. In Wood, W.B. (ed.) The Nematode Caenorhabditis elegans. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, New York, pp. 393—112. 

Riddle, D.L., Swanson, M.M. and Albert, P.S. (1981) Interacting genes in nematode dauer larva formation. Nature 290, 668-671. 

Fig. 8.5. Transmission electron micrograph of a transverse section through an infective dauer larva of Anguina agrostis (funesta) showing Clavibacter toxicus adhering to the cuticle and causing pathological changes to the cuticle surface (arrows). Scale bar = 1 pm.

Golden, J.W. and Riddle, D.L. (1984) The Caenorhabditis elegans dauer larva developmental effects of pheromone, food, and temperature. Developmental Biology 102, 368—378. 

Cassada, R. and Russell, R. (1975) The dauer larva, a post-embryonic developmental variant of the nematode Caenorhahditis ehgans. Devebpmental Biology 46, 326-342. 

High expression in Trichnella muscle larva of thymidylate synthase, and certain other enzymes involved in DNA biosynthesis, was found also in Caenorhabditis dauer larva and appears to be connected with their cells being arrested in the cell cycle. 

Table 1 Specific activities of selected enzymes involved in thymidylate de novo biosynthesis in T. spiralis and T. pseudospiralis muscle larvae, T. spiralis adult forms, C. ekgans adult forms, and LI, L3 and dauer larvae. For both Trichinella species time between infection and isolation is indicated... 

The culture prepared to obtain dauer larvae was continued for the time indicated... 

In C. elegans development, the specific activities of the three enzymes involved in dTMP biosynthesis, thymidylate synthase, dUTPase and dihydrofolate reductase, were high in adult forms, LI, L3 and dauer larvae (Table 1). Thymidylate synthase activity was not lowered when dauer larvae remained up to 6 weeks in the culture (Table 1). When measured in an extract from dauer larvae that were obtained from a starved stock culture based on their climbing behaviour (Riddle and Albert 1997), thymidylate synthase activity was found to be similarly high (0.18 nmol/min/mg protein N = 1). 

Ribonucleotide reductase activity, comparable to that (0.7 nmol/h/mg protein N = 1) determined in murine leukemia LI210 cells (harvested in the logarithmic phase of growth) was fund in extracts from T. spiralis muscle larvae (0.2 nmol/h/mg protein N = 1), as well as from all C. elegans developmental forms studied, including dauer larvae (0.47 0.07 nmol/h/mg protein N = 3), mixed population of developing larvae (0.64 6% mnol/h/mg protein N = 2) and adults (0.7 0.06 nmol/h/mg protein N = 3). 

Expression of Thymidylate Synthase mRNA and 18S rRNA in Adult Worms, Embryos and LI, L3 and Dauer Larvae of C. elegans... 

The pattern of thymidylate synthase mRNA level in C. elegans development is rather poorly correlated with proliferation, as dauer larvae, lacking cell divisions... 

Euling and Ambros 1996 Riddle 1988 Wadsworth and Riddle 1988), show considerable level of this mRNA (Fig. la and b). hi accord with thymidylate synthase specific activity, the enzyme mRNA level persists in dauer larvae for at least 6 weeks (Table 1 cf. Fig. 1). Additionally, comparison of the enzyme activity, enzyme protein and mRNA levels in adult worms, and LI, L3 and dauer larvae, shows only the enzyme protein and mRNA patterns (Table 1, Fig. 1, Results) to be correlated. Interestingly, the enzyme activity pattern parallels the two former patterns only with LI, L3 and dauer larvae, with the enzyme activity level in adult forms being low, relative to both mRNA and enzyme protein levels. The latter points to some regulation of enzyme protein expression and activity during the development. Of note is that T. spiralis thymidylate synthase mRNA levels showed no differences between adults, newborns and muscle larvae, with the enzyme specific activities in adults and muscle larvae also being comparable (Table 1, Fig. 1). 

Riddle DL (1988) The dauer larva. In Wood WB (ed) The nematode Caenorhabditis elegans. 

Cold Spring Harbor Laboratory Press, New York, pp 393-412 Riddle DL, Albert PS (1997) Genetic and environmental regulation of dauer larva development. In Riddle DL, Blumenthal T, Meyer BJ, Priess JR (eds) C. elegans II. Cold Spring Harbor Laboratory Press, New York, pp 739-768... 

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