Showing papers on "Uca pugilator published in 2009"
01 Jan 2009-Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology
TL;DR: An analysis of the claw-waving displays of seven Australian species of fiddler crab found that the structure and timing of the displays is species-specific, exhibiting inter-specific differences that follow phylogenetic relationships.
Abstract: Fiddler crabs use elaborate, species-specific claw-waving displays to communicate with rivals and mates. However, detailed comparative studies of fiddler crab signal structure and structural variations are lacking. This paper provides an analysis of the claw-waving displays of seven Australian species of fiddler crab, Uca mjoebergi, U. perplexa, U. polita, U. seismella, U. signata, U. elegans and U. vomeris. We used digital video to record and analyse the fine-scale spatiotemporal properties of these movement-based visual signals. We found that the structure and timing of the displays is species-specific, exhibiting inter-specific differences that follow phylogenetic relationships. The displays showed intra-specific variation according to individual identity, geographic location and fine-scale behavioural context. The observed differences and variations are discussed in the light of the evolutionary forces that may shape their design.
38 citations
TL;DR: Both Aroclor 1242 and endosulfan were found to be capable of antagonizing ecdysteroid signaling in cultured epidermal tissues, which can at least partly explain the inhibitory effects of these two agents on crustacean molting.
Abstract: Because of their chemical stability and lipophilicity, many organochlorine compounds (OCs) can readily accumulate in fatty tissues of crustaceans. Several OCs have been reported to inhibit crustacean molting. To determine whether the disruption of crustacean molting by these OCs involves interference with ecdysteroid signaling in the epidermis, the impacts of five molt-inhibiting OCs on the level of N -acetyl-β-glucosaminidase (NAG, EC 3.2.1.30) mRNA in cultured epidermal tissues from the fiddler crab, Uca pugilator , were investigated using quantitative real-time PCR. The NAG mRNA was found to be inducible by 20-hydroxyecdysone (20-HE) in cultured epidermal tissues. The inducibility of NAG mRNA in cultured epidermal tissues by 20-HE is not only further direct evidence that epidermal expression of NAG gene in U. pugilator is controlled by the molting hormone but also validates the use of the NAG mRNA as a biomarker for epidermal ecdysteroid signaling. When Aroclor 1242, 2,4,5-trichlorobiphenyl (PCB29), endosulfan or kepone was administered alone, the expression of NAG gene in cultured epidermal tissues was upregulated, while heptachlor had no effects. Under binary exposure to both 20-HE and an OC, a condition similar to the natural hormonal milieu of epidermal tissues of animals impacted by OCs, both Aroclor 1242 and endosulfan were found to be capable of antagonizing ecdysteroid signaling in cultured epidermal tissues. This antagonizing effect on epidermal ecdysteroid signaling can at least partly explain the inhibitory effects of these two agents on crustacean molting. PCB29, when given together with 20-HE, produced an additive effect on epidermal ecdysteroid signaling but such an additive effect was not observed when kepone was combined with 20-HE.
20 citations
TL;DR: The results of the present investigation show that the transcription of NAG gene in the epidermis of the fiddler crab, Uca pugilator, is inducible by the molting hormone 20-hydroxyecdysone, which validates the use of N AG mRNA as a biomarker for molt-disrupting effects of xenobiotics.
Abstract: Several environmentally persistent chemicals have been found to be capable of disrupting crustacean molting. Considering the importance of molting in the life of crustaceans, there is a need to develop a molecular biomarker that can reflect the disrupting effects of contaminants on ecdysteroid signaling in crustaceans. N-acetyl-β-glucosaminidase (NAG) is a chitinolytic enzyme found in crustacean epidermis. The results of the present investigation show that the transcription of NAG gene in the epidermis of the fiddler crab, Uca pugilator, is inducible by the molting hormone 20-hydroxyecdysone, which validates the use of NAG mRNA as a biomarker for molt-disrupting effects of xenobiotics.
12 citations
TL;DR: In an effort to obtain biologically active tyrosine analogs of the octadecapeptide pigment-dispersing hormone (β-PDH) of the fiddler crab Uca pugilator, the authors have synthesized [Tyr15]- and [Nle18]-β- PDH analogs by the solid phase method.
Abstract: In an effort to obtain biologically active tyrosine analogs of the octadecapeptide pigment-dispersing hormone (β-PDH) of the fiddler crab Uca pugilator, we have synthesized [Tyr15]- and [Nle18]-β-PDH, as well as eight tyrosine analogs of [Nle15]-β-PDH by the solid-phase method. Each analog was purified to homogeneity by gel filtration, ion-exchange chromatography, and partition chromatography. When tested for melanophore pigment-dispersing activity in destalked Uca, [Nle15, Tyr16]-β-PDH and [Nle15]-β-PDH were found to be 31-fold and 16-fold more potent, respectively, than β-PDH. Somewhat reduced potency was displayed by [N-Tyr,Nle15]-β-PDH (81%) and [Nle15, Tyr17]-β-PDH (26%). All other analogs, including [Nle15, Tyr19]-β-PDH and the four derivatives of [Nle15]-β-PDH obtained through substitution for nonpolar amino acid residues at positions 4, 5, 8, and 11 in the primary structure, showed marked decrease in biological activity (0.01 to 2% potency).
5 citations
4 citations
TL;DR: The Uca panacea and Uca pugilator are closely related North American species that are sympatric along the north coast of Gulf of Mexico as discussed by the authors, and there has been confusion in the identification of these two species.
Abstract: The fiddler crabs Uca panacea Novak & Salmon, 1974 and Uca pugilator (Bosc, 1802) are closely related North American species that are sympatric along the north coast of Gulf of Mexico. Since U. panacea was described, there has been confusion in the identification these two species. Morphological differences between these two fiddlers have been pointed out in recent years, mainly regarding the presence of a pigment spot and granulations on the dorsal margin of carapace in U. pugilator. We report herein some intraspecific differences between the two species that we believe to be useful in avoiding misidentification among preserved specimens of these two fiddler crabs, such as the absence of the pigment spot in U. pugilator and the presence of the pigment spot and granulations on dorsal margin of carapace in U. panacea as well. Our results have also revealed that 65% of the U. pugilator specimens examined possess a gape pile in the major chela, which is not a reliable diagnostic character, but could be useful when present. The gonopods of both species were analyzed using SEM, confirming the previous statement that the sub-terminal thumb is shorter in U. panacea than in U. pugilator. Finally, as important morphological characters are missing in the original description of U. panacea, a redescription of this species is also provided.
4 citations
01 Jan 2009
3 citations
3 citations
01 Jan 2009
TL;DR: Insight is provided into the workings of the crustacean nervous system and shows that fiddler crabs are a model organism in which to examine the effects of excitotoxicity, which may lead to future knowledge about the mechanisms of neurodegenerative diseases.
Abstract: Part of the Biology Commons Colby College theses are protected by copyright. They may be viewed or downloaded from this site for the purposes of research and scholarship. Reproduction or distribution for commercial purposes is prohibited without written permission of the author. Glutamate is the primary excitatory neurotransmitter in the mammalian central nervous system. It is of particular interest because of its supposed role in the processes of learning and memory, and also because of its potential toxic effects that have been linked to neurodegenerative diseases, such as Alzheimer's and Parkinson's. Although glutamate is necessary for normal cell functioning, high levels of glutamate receptor activation can result in cell death, a phenomenon known as excitotoxicity. It has been suggested that glutamate also plays an important role in the insect and crustacean nervous systems, allowing for the examination of excitotoxicity in these organisms. The current study aims to determine the effect of high concentrations of glutamate on the neurite outgrowth of cultured fiddler crab (Uca pugilator) cells. Cells were obtained from the x-organ, a neurohemal organ located in the crustacean eyestalk, and were cultured for 24 hours in simple culture medium. After 24 hours, cells exhibiting neurite outgrowth were photographed and treated with one of four concentrations of glutamate. The treatment groups included: control with 0 mM glu, 0.1 mM glu, 1 mM glu, and 10 mM glu. After another 24 hours, the cells were photographed a second time and the neurite outgrowth was measured and compared. Higher concentrations of glutamate had a negative effect on neurite outgrowth, causing the neurites to retract or slow their growth. Glutamate receptors were also located in the x-organ cells using immunocytochemistry with fluorescence. This study provides insight into the workings of the crustacean nervous system and shows that fiddler crabs are a model organism in which to examine the effects of excitotoxicity, which may lead to future knowledge about the mechanisms of neurodegenerative diseases.