Uca Pugilator

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Milton Fingerman - One of the best experts on this subject based on the ideXlab platform.

  • HEAT TOLERANCE AND TEMPERATURE RELATIONSHIPS OF THE FIDDLER CRAB, Uca Pugilator, WITH REFERENCE TO BODY COLORATION
    2015
    Co-Authors: Jerrel L, Milton Fingerman
    Abstract:

    Fiddler crabs, Uca, being inhabitants of the littoral zone, offer a ready oppor tunity for study of physiological adaptations associated with the intermediate step in the migration of crustaceans from an aquatic to a terrestrial habitat. Poikilo therms, in general, that have left the aquatic environment require, among others, adequate mechanisms to survive greater extremes of temperature than they had experienced previously. Fiddler crabs are generally active and feeding about the time of low tide. Consequently, when how tide occurs in the middle of the day during the warmer months of the year fiddler crabs on open beaches are exposed to temperatures that are near the lethal level because of the direct solar radiation (Teal,1958). The fiddler crab, Uca Pugilator, exhibits a daily rhythm of color change (Abramowitz, 1937). Specimens are darker during the daytime than at night because the chroniatophorah pigments are more dispersed. Brown and Sandeen (1948) , working with the same species, found that during the day phase of the rhythm the black pigment tends to concentrate as the temperature rises abov

  • Environmental Factors Involved in Setting the Phases of Tidal Rhythm of Color Change in the Fiddler Crabs Uca Pugilator and Uca minaxl
    2014
    Co-Authors: Milton Fingerman, Mildred E. Lowe, C. Mobberly
    Abstract:

    Observations were performed to detcrminc the relationship bctwccn the time of maximal pigment dispersion in the fiddler crabs, Uca Pugilator and Uca minax, and the tidal events on the beach where the crabs were collcctcd. Uca Pugilator obtained from burrows above the high tide mark did not have an overt tidal rhythm but did have 24-hour and 14.8-day cycles of color change. The tidal rhythm was probably suppressed bccausc the crabs wcrc free to leave their burrows at any time, whereas crabs from the intertidal zone can lcavc only when the area where their burrows are located is uncovered by the receding water. Crabs living in the intertidal zone displayed a typical tidal rhythm of color change. The tidal maximum of pigment dispersion progressed across the 24-hour cycle at the usual rate. Analysis of the tidal rhythms of two groups of crabs, Uca Pugilator, collected near the high and low tide marks, respectively, rcvealcd that crabs from burrows near the low tide mark behaved as if low tide occurred.for them 9.8 hours later each day than for the high tide crabs. Crabs living near the low tide mark annearcd on the beach 10.1 hours later than crabs living near Lhe high tide mark. As a &ult of these observations the hypothesi

  • inhibition of ovarian growth by cadmium in the fiddler crab Uca Pugilator decapoda ocypodidae
    Ecotoxicology and Environmental Safety, 2000
    Co-Authors: Enrique M. Rodríguez, Laura Lopez S Greco, Milton Fingerman
    Abstract:

    The effect of cadmium chloride (1 mg/L) on oocyte growth of the fiddler crab, Uca Pugilator, was studied during the slow vitellogenesis phase of ovarian maturation of this carb. In vivo experiments were done with both intact and eyestalkless crabs. The intact cadmium-exposed crabs exhibited a significantly lower oocyte diameter than the controls at the end of the 2-week exposure period, but no significant differences were detected among the eyestalkless crabs, suggesting that the effect of cadmium could be on the sinus gland in the eyestalks, increasing secretion of the gonad-inhibiting hormone (GIH). To test this hypothesis, in vitro experiments were done, incubating pieces of ovary with and without eyestalk tissue, in the presence of thoracic ganglion, needed for oocyte growing due to the secretion of the gonad-stimulating hormone (GSH). Only when eyestalk tissue was present in the incubation media was oocyte growth inhibited by cadmium compared to the controls. These results strongly suggest that cadmium acts at least in part to increase the secretion of GIH from the sinus gland. GIH could then in turn act by (a) inhibiting secretion of GSH by the thoracic ganglion, (b) directly inhibit the oocytes, or (c) both (a) and (b).

  • roles of neurotransmitters in regulating reproductive hormone release and gonadal maturation in decapod crustaceans
    Invertebrate Reproduction & Development, 1997
    Co-Authors: Milton Fingerman
    Abstract:

    Summary Experiments done in this laboratory showed 5-hydroxytryptamine (5-HT) stimulates gonadal maturation in male and female sand fiddler crabs, Uca Pugilator, and red swamp crayfish, Procambarus clarkii. This action of 5-HT is indirect, 5-HT apparently stimulating release of the gonad-stimulating hormone (GSH) that is present in the brain and thoracic ganglia. For example, studies with ovarian explants showed 5-HT has no direct effect on the ovary. But, when ovarian explants were incubated with 5-HT and brain or thoracic ganglia, the incubation medium produced greater ovarian maturation than did the medium when ovarian explants were incubated with brain or thoracic ganglia alone, 5-HT presumably enhancing GSH release. In males 5-HT not only induces testicular maturation but also development of the androgenic glands. 5-HT in males, as in females, apparently triggers GSH release; but in males GSH in turn stimulates the androgenic glands which release the androgenic gland hormone, resulting in testicular ...

David S. Durica - One of the best experts on this subject based on the ideXlab platform.

  • Ecdysteroid receptor signaling disruption obstructs blastemal cell proliferation during limb regeneration in the fiddler crab, Uca Pugilator.
    Molecular and cellular endocrinology, 2012
    Co-Authors: Sunetra Das, David S. Durica
    Abstract:

    To study ecdysteroid signaling during limb regeneration, we have applied RNAi (dsRNA) mediated silencing to EcR/RXR, the genes encoding the ecdysteroid receptor heterodimer, in the fiddler crab Uca Pugilator. We injected RNAi into the blastemal chamber during early limb regeneration. Silencing was evaluated by knockdown in receptor transcript abundance, and disruption was evaluated by changes in growth rate and morphology of limb regenerates. q-PCR results indicated a 50% drop in transcript abundance 48h post injection in both RNAi (dsEcR/dsRXR) injected ipsilateral and uninjected contralateral blastemas in experimental animals relative to controls. EcR/RXR transcript levels further decreased over time. Several phenotypes were associated with knockdown. The experimental blastema failed to develop; microscopic examination of the arrested blastema revealed an absence of the cuticular ingrowths characteristic of the beginnings of limb segmentation and cell proliferation assays revealed that the arrested blastema had few dividing cells. Ecdysteroid levels were also lowered in experimental animals; given the bilateral effects of RNAi on limb buds in experimental animals, these results suggest RNAi had a systemic effect. Although hormone titers in experimental animals rose to comparable control levels during the late proecdysial phase of limb regeneration, most experimental crabs failed to molt and died. The overall failure to molt indicates that RNAi receptor knockdown has long-term effects. The combined effects of receptor knockdown indicate that, although circulating ecdysteroid titers are normally low during basal limb bud growth, signaling via the ecdysteroid receptor pathway is necessary for establishment of blastemal cell proliferation and development in the regenerating limbs of U. Pugilator.

  • rxr isoforms and endogenous retinoids in the fiddler crab Uca Pugilator
    Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2008
    Co-Authors: Penny M Hopkins, David S. Durica, Tracy Washington
    Abstract:

    The pleiotropic effects of circulating ecdysteroids in the adult fiddler crab, Uca Pugilator, during molting, regeneration, and reproduction are mediated by a limited number of receptor proteins. We hypothesize that hormonal effects in vivo may be the result of complex interactions between at least two receptor heterodimer conformations that differentially respond to multiple ecdysteroid/retinoid signals. Two splicing variants of the fiddler crab retinoid-X-receptor (UpRXR) differ from one another by the addition of a 33 amino acid insert in the ligand-binding domain. We show here that the ecdysteroid receptor in the fiddler crab (UpEcR) behaves differently depending upon the UpRXR isoform with which it is partnered. The two UpRXR variant partners for UpEcR confer slightly different responses in the binding of Ponasterone A (PA)-a naturally occurring ecdysteroid in the blood of Uca. UpRXR can bind 9-cis retinoic acid (9cRA) as well as terpenoids. 9cRA and the naturally occurring terpenoid, methyl farnesoate, influence the binding of PA to UpEcR/UpRXR dimers. Endogenous retinoids are found in the blastema of regenerating limbs of Uca and they (plus blood-borne terpenoids) may add additional levels of differential response by target tissues. Thus, the two sets of heterodimers tested here may represent different dynamic complexes whose properties are defined by the specific heterodimeric subunits involved and the specific ligands available.

  • est library sequencing of genes expressed during early limb regeneration in the fiddler crab and transcriptional responses to ecdysteroid exposure in limb bud explants
    Integrative and Comparative Biology, 2006
    Co-Authors: David S. Durica, Penny M Hopkins, Doris M Kupfer, Fares Z Najar, Hongshing Lai, Yuhong Tang, Kathryn Griffin, Bruce A Roe
    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.

Penny M Hopkins - One of the best experts on this subject based on the ideXlab platform.

  • rxr isoforms and endogenous retinoids in the fiddler crab Uca Pugilator
    Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2008
    Co-Authors: Penny M Hopkins, David S. Durica, Tracy Washington
    Abstract:

    The pleiotropic effects of circulating ecdysteroids in the adult fiddler crab, Uca Pugilator, during molting, regeneration, and reproduction are mediated by a limited number of receptor proteins. We hypothesize that hormonal effects in vivo may be the result of complex interactions between at least two receptor heterodimer conformations that differentially respond to multiple ecdysteroid/retinoid signals. Two splicing variants of the fiddler crab retinoid-X-receptor (UpRXR) differ from one another by the addition of a 33 amino acid insert in the ligand-binding domain. We show here that the ecdysteroid receptor in the fiddler crab (UpEcR) behaves differently depending upon the UpRXR isoform with which it is partnered. The two UpRXR variant partners for UpEcR confer slightly different responses in the binding of Ponasterone A (PA)-a naturally occurring ecdysteroid in the blood of Uca. UpRXR can bind 9-cis retinoic acid (9cRA) as well as terpenoids. 9cRA and the naturally occurring terpenoid, methyl farnesoate, influence the binding of PA to UpEcR/UpRXR dimers. Endogenous retinoids are found in the blastema of regenerating limbs of Uca and they (plus blood-borne terpenoids) may add additional levels of differential response by target tissues. Thus, the two sets of heterodimers tested here may represent different dynamic complexes whose properties are defined by the specific heterodimeric subunits involved and the specific ligands available.

  • est library sequencing of genes expressed during early limb regeneration in the fiddler crab and transcriptional responses to ecdysteroid exposure in limb bud explants
    Integrative and Comparative Biology, 2006
    Co-Authors: David S. Durica, Penny M Hopkins, Doris M Kupfer, Fares Z Najar, Hongshing Lai, Yuhong Tang, Kathryn Griffin, Bruce A Roe
    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.

  • Limb regeneration in the fiddler crab, Uca Pugilator: hormonal and growth factor control
    2001
    Co-Authors: Penny M Hopkins
    Abstract:

    SYNOPSIS. This paper summarizes recent work on various aspects of hormonal control of regeneration in the crustacean, Uca Pugilator. Hormonal control in this crab is effected by means of the crustactean steroid hormones, the ecdysteroids. New evidence is presented supporting a role for the retinoid hormones, all-trans retinoic acid and 9-cis retinoic acid, in the control of regeneration in these animals. The possible role of fibroblast growth factors in organization of the limb blastema is explored and the similarities between vertebrate and invertebrate control of regeneration are discussed. REGENERATION IN CRUSTACEANS The hard exoskeleton of crustaceans makes growth in these animals quite remarkable. In order to increase in size, these animals must periodically shed (called molt or ecdysis) their old exoskeleton, then expand a new, soft, pliant exoskeleton that has been formed beneath the old one. The length of time from one molt to the next is called the intermolt cycle. The length of the cycle is variable and determined by time of year, nutritional status, and other factors including whether or not the animal is regenerating a limb. Regeneration is a special type of growth found in many crustaceans. In the fiddler crab Uca Pugilator, limbs that are lost due to injury or predation and as a result of the reflexive autotomy response, can be regenerated completely during a single intermolt cycle (for reviews see Skinner, 1985; Hopkins, 1993; Hopkins et al., 1999). Autotomy occurs at the base of all walking legs. Regardless of where along the length of the limb an injury occurs, the autotomy response insures that the limb is cast off at a predetermined point at the base of the leg between the coxa and the basiischium. Loss at the predetermined point insures the most efficient and fastest regeneration. Regener

Blaine D Griffen - One of the best experts on this subject based on the ideXlab platform.

  • individual movement rates are sufficient to determine and maintain dynamic spatial positioning within Uca Pugilator herds
    Behavioral Ecology and Sociobiology, 2016
    Co-Authors: Eilea R Knotts, Blaine D Griffen
    Abstract:

    Spatial location within aggregations (i.e., periphery, central) is of biological significance to gregarious animals. Because these positions are a potential consequence of consistent individual behavioral differences, or personality, a better understanding of potential mechanisms concerning personality is central to predicting an individuals’ location. To determine the effects of individual personality on the dynamic spatial positioning of Uca Pugilator while herding, field data collection and agent-based modeling were employed. Individuals were assayed to establish their personalities and returned to the field for observation as a means of identifying location preference within selfish herds. There was a significant difference between the extreme personalities and the proportion of time spent on the edge of the herd. The active individuals were at the periphery ~50 % more of the time than less active individuals. An individual-based model qualitatively replicated these field results by applying the mechanism of activity level as an indicator of individual personality. This suggests that differences in personality-dependent movement are sufficient to explain the spatial positioning of individuals within selfish herds. This study enhances our understanding of the possible mechanisms that govern group movement, and has implications for modeling population dynamics that can be influenced by individual personality. Animal personality influences the level of exploratory activity of individual animals, with some individuals being consistently more active and others consistently less active, and may therefore be used to mechanistically predict the location of individual animals within groups or herds. Here, we investigate the relationship between individual personality and location on the edge vs. in the center of foraging herds of the sand fiddler crab Uca Pugilator. We combine observational testing of activity level in lab, observations of spatial positioning within herds in the field, and agent-based computer simulation modeling to demonstrate that differences in exploratory movement can sufficiently explain the spatial positioning of individuals within herds. Thus, the spatial positioning of individual animals within herds can be explained without relying on choices by individual animals.

  • correlating context specific boldness and physiological condition of female sand fiddler crabs Uca Pugilator
    Journal of Ethology, 2012
    Co-Authors: Rachel A Decker, Blaine D Griffen
    Abstract:

    Consistent individual behavioral differences across ecological contexts are a recognized feature of animal populations. These differences can be expressed in two ways: context-specifically or context-generally. The former is characterized by consistent responses in one context (i.e. repeatability), whereas the latter by consistency that spans contexts (i.e. behavioral syndromes). The proximate causes of behavioral consistency remain unclear, yet there is evidence that physiology may couple the expression of some behavioral traits in unrelated contexts. We therefore explored the correlation between bold behavior of female sand fiddler crabs (Uca Pugilator) and the condition of the hepatopancreas, an organ vital to crustacean metabolism and reproduction. We did this by taking replicate measurements of two risk-taking behaviors per individual in the contexts of predator avoidance and environment exploration, and examining correlations within and between these observations. We then determined the relationship of behavior with hepatopancreas mass and lipid content. Individual crabs responded consistently within each context. However, across-context correlations were absent, indicating that boldness is isolated, at least in the selected scenarios. Additionally, anti-predator and exploratory behaviors were significantly influenced by size but not linked to hepatopancreas physiology. Our results show that context-specific trait expression may occur in the absence of a physiological correlate.

Horacio O De La Iglesia - One of the best experts on this subject based on the ideXlab platform.

  • influence of temperature on daily locomotor activity in the crab Uca Pugilator
    PLOS ONE, 2017
    Co-Authors: Audrey M Mat, Gideon P Dunster, Valerio Sbragaglia, Jacopo Aguzzi, Horacio O De La Iglesia
    Abstract:

    Animals living in the intertidal zone are exposed to prominent temperature changes. To cope with the energetic demands of environmental thermal challenges, ectotherms rely mainly on behavioral responses, which may change depending on the time of the day and seasonally. Here, we analyze how temperature shapes crabs’ behavior at 2 different times of the year and show that a transition from constant cold (13.5°C) to constant warm (17.5°C) water temperature leads to increased locomotor activity levels throughout the day in fiddler crabs (Uca Pugilator) collected during the summer. In contrast, the same transition in environmental temperature leads to a decrease in the amplitude of the daily locomotor activity rhythm in crabs collected during the winter. In other words, colder temperatures during the cold season favor a more prominent diurnal behavior. We interpret this winter-summer difference in the response of daily locomotor activity to temperature changes within the framework of the circadian thermoenergetics hypothesis, which predicts that a less favorable energetic balance would promote a more diurnal activity pattern. During the winter, when the energetic balance is likely less favorable, crabs would save energy by being more active during the expected high-temperature phase of the day—light phase—and less during the expected low-temperature phase of the day—dark phase. Our results suggest that endogenous rhythms in intertidal ectotherms generate adaptive behavioral programs to cope with thermoregulatory demands of the intertidal habitat.