Short-term changes in dorsal reflectance for background matching in Ornate Tree Lizards (Urosaurus ornatus)

2008 ◽  
Vol 29 (4) ◽  
pp. 473-477 ◽  
Author(s):  
Paul Hamilton ◽  
Brian Sullivan ◽  
Diann Gaalema
Keyword(s):  
Short Term ◽  
Urosaurus Ornatus ◽  
Male And Female ◽  
Background Matching ◽  
Environmental Extremes ◽  
Tree Lizards

AbstractSome lizards are thought to exhibit short-term changes in color to match their background, but this ability has not been verified empirically. We tested the hypothesis that lizards will change dorsal reflectance over a series of days to match their backgrounds. We housed male and female Ornate Tree Lizards (Urosaurus ornatus) for five days in aquaria painted to match environmental extremes in substrate reflectance. Standardized photographs were taken each day yielding dorsal percent reflectance values. After the first day, reflectance of lizards changed significantly to more closely match their backgrounds; this effect became more pronounced through the fifth and final day of the experiment.

Amorphous silica nanoparticles induced spleen and liver toxicity after acute intravenous exposure in male and female rats

2021 ◽  
pp. 074823372110105
Author(s):  
Roberta Tassinari ◽  
Andrea Martinelli ◽  
Mauro Valeri ◽  
Francesca Maranghi
Keyword(s):  
Amorphous Silica ◽  
Liver Toxicity ◽  
Female Rats ◽  
Histopathological Analysis ◽  
Short Term ◽  
Short Term Treatment ◽  
Male And Female ◽  
Male And Female Rats ◽  
Target Organs ◽  
Short Term Exposure

Synthetic amorphous silica (SAS) nanomaterial – consisting of aggregates and agglomerates of primary silicon dioxide (SiO2) particles in the nanorange (<100 nm) – is commonly used as excipient in pharmaceuticals, in cosmetics and as food additive (E551). The available data suggest that SAS nanoparticles (NP) after intravenous (IV) exposure persist in liver and spleen; however, insufficient data exist to verify whether SAS may also induce adverse effects. The aim of the present study was to verify the potential long-term effects of SAS NP (NM-203) on spleen and liver as target organs following short-term exposure. Adult male and female Sprague-Dawley rats were treated by IV injection in the tail vein with a single (1-day) dose (SD) and repeated (5-day) doses (RD) of 20 mg/kg bw per day of SAS dispersed in sterile saline solution as vehicle. Histopathological examinations of target organs were performed after 90 days. Tissue biodistribution and full characterization of NM-203, primary particle size 13–45 nm, was performed within the framework of the Nanogenotox project. No mortality or general toxicity occurred; histopathological analysis showed splenomegaly in the RD group accompanied by inflammatory granulomas in both sexes. Granulomas were also present in liver parenchyma in the RD (both sexes) and SD groups (male only). The histopathological results indicated that SAS NP have the potential to persist and induce sex-specific chronic inflammatory lesions in spleen and liver upon short-term treatment. Overall, the data showed that the widespread use of silica in drugs might elicit chronic reactions in spleen and liver prompting to the need of further investigations on the safety of SAS NP.

Effects of adrenocorticotropin on temperature- and pressure-dependent metabolic functions

1959 ◽  
Vol 197 (6) ◽  
pp. 1291-1296 ◽  
Author(s):  
Henry B. Hale ◽  
Roy B. Mefferd
Keyword(s):  
Barometric Pressure ◽  
Male Rats ◽  
Short Term ◽  
Metabolic Functions ◽  
Metabolic States ◽  
Environmental Extremes ◽  
Temperature And Pressure ◽  
Hot Environments ◽  
Low Dosage

Effects of adrenocorticotropin (ACTH) in low dosage on metabolic aspects were determined in adult male rats acclimated to cold, neutral or hot environments or to low barometric pressure. Urinary determinations provided the means for indirectly assessing metabolic states. The metabolic aspects studied were Na, K, Ca, P, Mg, urea, uric acid, creatinine, creatine, taurine, ß-alanine, glycine, α-alanine, valine, methionine, serine, threonine, tyrosine, glutamic acid, aspartic acid, lysine, arginine, histidine, glucose, glucuronic acid, phenolic acids and coproporphyrin. Additionally, fecal determinations were made for coproporphyrin, protoporphyrin and deuteroporphyrin. The interplay between endocrine and environmental factors and their importance to metabolic states during short-term and long-term exposures to environmental extremes thus received some clarification. With the low dosage employed, ACTH had a ‘restraining’ influence on nonspecific metabolic responses.

Intraspecific variation in tree lizard escape behaviour in relation to habitat and temperature

Behaviour ◽  
2020 ◽  
Vol 157 (2) ◽  
pp. 185-204 ◽  
Author(s):  
Cynthia L. Morris ◽  
Matthew S. Lattanzio
Keyword(s):  
Antipredator Behaviour ◽  
Similar Response ◽  
Response Patterns ◽  
Escape Behaviour ◽  
Urosaurus Ornatus ◽  
Escape Theory ◽  
Habitat Gradients ◽  
Disturbance Gradient ◽  
Tree Lizards ◽  
Tree Lizard

Abstract Optimal escape theory has proven useful for understanding the dynamics of antipredator behaviour in animals; however, approaches are often limited to single-population studies. We studied how the escape behaviour of tree lizards (Urosaurus ornatus) varied across a disturbance gradient. We also considered how sex, body temperature, and perch temperature affected their escape decisions. Both sexes exhibited similar response patterns; however, lizards in the most-disturbed habitat, as well as cooler (body or perch temperature) lizards, initiated escape earlier (but did not flee further) than other animals. Increased wariness as indicated by earlier escape suggests that frequently-disturbed, more-open localities may be stressful habitats for species like U. ornatus. In addition, because cooler temperatures limit locomotor performance capacity, escape decisions should also depend on a species’ thermal ecology. Overall, we stress the importance of multi-population approaches for capturing the variety of ways species adaptively respond to the threat of predation across habitat gradients.

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