Showing papers on "Uca pugilator published in 2006"

How dear is my enemy: Intruder-resident and resident-resident encounters in male sand fiddler crabs (Uca pugilator)

Abstract: Male sand fiddler crabs (Uca pugilator) defend territories that consist of a breeding burrow and a display area where they wave their claw to attract females. Burrow-holding males engage in agonistic contests with both intruding males that attempt burrow take-overs and with other territory-holding neighbors that apparently attempt to limit waving or other surface activities of rivals. Contests employ one or more behavioral elements that range from no claw contact to use of the claw to push, grip, or flip an opponent. We placed each observed element into one of six groups ranked by intensity, which was based on the degree of claw contact and apparent energy expenditure. In the field, contests with intruders began at higher intensity and escalated more rapidly than did those with neighbors. Thus, U. pugilator males exhibit a dear enemy response toward neighbors. However, resident-resident contests increased in intensity when burrows were close, neighbors faced each other when exiting burrows, and neighbors were of similar size. Proximity and orientation determine the ease with which a neighbor may be engaged. Also, neighbors that are close and of similar size pose a greater threat to mating opportunities, favoring heightened intensity of contests.

EST library sequencing of genes expressed during early limb regeneration in the fiddler crab and transcriptional responses to ecdysteroid exposure in limb bud explants.

Abstract: We have constructed directional and randomly primed cDNA libraries from mRNAs isolated during progressive stages of fiddler crab (Uca pugilator) limb regeneration. Data from these libraries are being assembled into an on-line database (http://www.genome.ou.edu/crab.html) that is both BLAST and keyword searchable; the data set is also available through GenBank. The first characterized library was made from mRNA isolated 4 days post-autotomy, when the first sign of morphological differentiation, cuticle secretion, is observed. Analysis of 1698 cDNA clones led to assignment of 473 contigs and 417 singlets, for a total of 890 sequences. Of these, ∼86% showed no assignments to characterized genes on database searching, while 14% could be assigned to a known ortholog in the COG (Clusters of Orthologous Groups) database. BLAST searches to specific protein domains in the Gene Ontology database led to assignments for ∼40% of the assembled sequences. Sequence similarity searches of other crustacean EST databases produced hits to 13-30% of the Uca query sequences. The ESTs include several genes that may be potentially ecdysteroid-responsive, such as homologs to chaperone proteins and cuticle protein genes, as well as homologs to arthropod proteins involved in retinoid/terpenoid metabolism. We have tested 3 potential candidate genes for their ability to be induced by ecdysteroid in limb bud explants; an arthropodial cuticle protein gene, and the nuclear receptor genes EcR and RXR. A subset of early blastemal limb buds (8 days post autotomy) show a positive response to ecdysteroid by 1-1.5 h, followed by a decrease in transcript abundance at longer periods of sustained incubation. Later stage buds (12 days post autotomy-late premolt) show decreases in steady-state mRNA levels by 1.5 h, or are completely refractory to ecdysteroid exposure.