Multiple sublethal chemicals negatively affect tadpoles of the green frog, Rana clamitans

USGS Publications Warehouse

Boone, Michelle D.; Bridges, Christine M.; Fairchild, James F.; Little, Edward E.

2005-01-01

Many habitats may be exposed to multiple chemical contaminants, particularly in agricultural areas where fertilizer and pesticide use are common; however, the singular and interactive effects of contaminants are not well understood. The objective of our study was to examine how realistic, sublethal environmental levels of ammonium nitrate fertilizer (0, 10, 20 mg/L and ammonium chloride control) and the common insecticide carbaryl (0 or 2.5 mg/L) individually and interactively affect the development, size, and survival of green frog (Rana clamitans) tadpoles. We reared tadpoles for 95 d in outdoor 1,000-L polyethylene ponds. We found that the combination of carbaryl and nitrate had a negative effect on development and mass of tadpoles compared to the positive effect that either contaminant had alone. Presence of carbaryl was generally associated with short-term increases in algal resources, including ponds exposed to both carbaryl and nitrate. However, with exposure to nitrate and carbaryl, tadpole mass and development were not positively affected as with one chemical stressor alone. The combination of these sublethal contaminants may reduce the ability of amphibians to benefit from food-rich environments or have metabolic costs. Our study demonstrates the importance of considering multiple stressors when evaluating population-level responses.

Tadpoles: the Biology of Anuran Larvae

USGS Publications Warehouse

McDiarmid, R.W.; Altig, R.

1999-01-01

The recent alarming declines in amphibian populations worldwide and the suitability of amphibians for use in answering research questions in disciplines as diverse as molecular systematics, animal behavior, ecology, and evolutionary biology have focused enormous attention on tadpoles. Yet despite this growing interest, relatively little is known about these fascinating creatures. n this invaluable reference, leading experts on tadpole biology relate what we currently know about tadpoles and what we might learn from them in the future. Tadpoles provides detailed summaries of tadpole morphology, development, behavior, ecology, and environmental physiology; explores the evolutionary consequences of the tadpole stage; synthesizes available information on their biodiversity, and presents a standardized terminology and an exhaustive literature review of tadpole biology.

Accumulation, metabolism and toxicity of parathion in tadpoles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hall, R.J.

1990-04-01

Earlier work exposing tadpoles to organophosphorus pesticides indicated the great resistance of tadpoles of the bullfrog (Rana catesbeiana) to these chemicals and their surprising ability to accumulate parathion and fenthion from water. These qualities seemed to make them an ideal model with which to test a hypothesis advanced by Burke and Ferguson, who noted that parathion is more toxic to resistant mosquitofish in static water than in flowing water--a reversal of the pattern normally seen. They believed that highly toxic metabolite paraoxon was produced by the fish and that its buildup in static systems resulted in the unexpected mortality. Amphibiansmore » have been shown to produce paraoxon and to accumulate the parent compound parathion to levels that are potentially hazardous to other organisms. In the course of examining paraoxon production by tadpoles, it would also be possible to learn more about their patterns of parathion uptake and elimination. Retention of residues is also a matter of concern given the high levels observed in the earlier studies.« less

Uptake of arsenic and metals by tadpoles at an historically contaminated Texas site

USGS Publications Warehouse

Clark, D.R.; Cantu, R.; Cowman, D.F.; Maxson, D.J.

1998-01-01

On 14 May 1994, tadpoles were collected from Lateral Pond and Municipal Lake in Bryan, Texas. These waters are immediately downstream from Finfeather Lake which was directly contaminated during 53 years of industrial production of arsenic (As)-based cotton defoliants. The tadpoles contained elevated levels of arsenic, chromium (Cr) and zinc (Zn). As far as it is known, the mean concentrations of As (6.87 p.p.m. wet weight) and Cr (6.91 p.p.m. wet weight) in cricket frog (Acris crepitans) tadpoles were the highest ever reported in tadpoles. The Zn in the tadpoles exceeded the levels found in sediments by six to 11 times. The concentrations of As, Cr and Zn in Finfeather Lake in 1994 may have been toxic because tadpoles could not be found there. Ranid tadpoles and a newly transformed ranid frog found dead in Lateral Pond and Municipal Lake in 1994 may indicate that the elements reached toxic levels in some individual amphibians. The concentrations of As, Cr and Zn found in the tadpoles in this study might be toxic to predators. Mortality of turtles showing symptoms linked to chronic exposure to As was reported in Finfeather Lake in 1973. Turtles were not reported in Finfeather Lake again until 1996. Observations at Municipal Lake in 1994-1996 showed abundant tadpoles and turtles but no snakes, which also have not been seen at Finfeather Lake. This absence of snakes may indicate that their sensitivity or exposure to the existing contaminants is greater than that of frogs and turtles.

Effects of salinity stress on Bufo balearicus and Bufo bufo tadpoles: Tolerance, morphological gill alterations and Na(+)/K(+)-ATPase localization.

PubMed

Bernabò, Ilaria; Bonacci, Antonella; Coscarelli, Francesca; Tripepi, Manuela; Brunelli, Elvira

2013-05-15

Freshwater habitats are globally threatened by human-induced secondary salinization. Amphibians are generally poorly adapted to survive in saline environments. We experimentally investigated the effects of chronic exposure to various salinities (5%, 10%, 15%, 20%, 25%, 30% and 35% seawater, SW) on survival, larval growth and metamorphosis of tadpoles from two amphibian populations belonging to two species: the green toad Bufo balearicus and the common toad Bufo bufo. In addition, gill morphology of tadpoles of both species after acute exposure to hypertonic conditions (20%, 25%, and 30% SW) was examined by light and electron microscopy. Tadpoles experienced 100% mortality above 20% SW in B. balearicus while above 15% SW in B. bufo. We detected also sublethal effects of salinity stress on growth and metamorphosis. B. bufo cannot withstand chronic exposure to salinity above 5% SW, tadpoles grew slower and were significantly smaller than those in control at metamorphosis. B. balearicus tolerated salinity up to 20% SW without apparent effects during larval development, but starting from 15% SW tadpoles metamorphosed later and at a smaller size compared with control. We also revealed a negative relation between increasing salt concentration and gill integrity. The main modifications were increased mucous secretion, detachment of external layer, alteration of epithelial surface, degeneration phenomena, appearance of residual bodies, and macrophage immigration. These morphological alterations of gill epithelium can interfere with respiratory function and both osmotic and acid-base regulation. Significant variations in branchial Na(+)/K(+)-ATPase activity were also observed between two species; moreover an increase in enzyme activity was evident in response to SW exposure. Epithelial responses to increasing salt concentration were different in the populations belonging to two species: the intensity of histological and ultrastructural pathology in B. bufo was greater and we

The Effect of Plasma Exposure on Tail Regeneration of Tadpoles Xenopus Laevis

NASA Astrophysics Data System (ADS)

June, Joyce; Rivie, Adonis; Ezuduemoih, Raphael; Menon, Jaishri; Martus, Kevin

2014-03-01

Wound healing requires a balanced combination of nutrients and growth factors for healing and tissue regeneration. The effect of plasma exposure on tail regeneration of tadpoles, Xenopus laevis is investigated. The exposure of the wound to the helium plasma immediately followed the amputation of 40% of the tail. Amputation of the tail initiates regeneration of spinal cord, muscle, notochord, skin and connective tissues. By 24 h, the wound was covered by wound epithelium and blastema was formed by day 5. There was increased angiogenesis in plasma exposed tail regenerate compared to the control following 5 d post amputation. Observed was an increase in NO production in the regenerate of plasma exposed tadpoles was derived from increased activity of nNOS and iNOS. Western blot analysis for vascular endothelial growth factor showed stronger bands for the protein in amputated tadpoles of both the groups. Analysis of the composition and characteristics of the plasma using optical emission spectroscopy indicates excited state species consisting of N2, N2+,and OH is present in the plasma. This study was supported, in part, by the NSF Grant 1040108.

Responses of tadpoles to hybrid predator odours: strong maternal signatures and the potential risk/response mismatch

PubMed Central

Chivers, Douglas P.; Mathiron, Anthony; Sloychuk, Janelle R.; Ferrari, Maud C. O.

2015-01-01

Previous studies have established that when a prey animal knows the identity of a particular predator, it can use this knowledge to make an ‘educated guess' about similar novel predators. Such generalization of predator recognition may be particularly beneficial when prey are exposed to introduced and invasive species of predators or hybrids. Here, we examined generalization of predator recognition for woodfrog tadpoles exposed to novel trout predators. Tadpoles conditioned to recognize tiger trout, a hybrid derived from brown trout and brook trout, showed generalization of recognition of several unknown trout odours. Interestingly, the tadpoles showed stronger responses to odours of brown trout than brook trout. In a second experiment, we found that tadpoles trained to recognize brown trout showed stronger responses to tiger trout than those tadpoles trained to recognize brook trout. Given that tiger trout always have a brown trout mother and a brook trout father, these results suggest a strong maternal signature in trout odours. Tadpoles that were trained to recognize both brown trout and brook trout showed stronger response to novel tiger trout than those trained to recognize only brown trout or only brook trout. This is consistent with a peak shift in recognition, whereby cues that are intermediate between two known cues evoke stronger responses than either known cue. Given that our woodfrog tadpoles have no evolutionary or individual experience with trout, they have no way of knowing whether or not brook trout, brown trout or tiger trout are more dangerous. The differential intensity of responses that we observed to hybrid trout cues and each of the parental species indicates that there is a likely mismatch between risk and anti-predator response intensity. Future work needs to address the critical role of prey naivety on responses to invasive and introduced hybrid predators. PMID:26041358

Tadpole-like artificial micromotor

NASA Astrophysics Data System (ADS)

Liu, Limei; Liu, Mei; Su, Yajun; Dong, Yonggang; Zhou, Wei; Zhang, Lina; Zhang, Hui; Dong, Bin; Chi, Lifeng

2015-01-01

We describe a polymer-based artificial tadpole-like micromotor, which is fabricated through the electrospinning technique. By incorporating functional materials onto its surface or within its body, the resulting tadpole-like micromotor can not only move autonomously in an aqueous solution with a flexible tail, but also exhibit thermo- and magnetic responsive properties.We describe a polymer-based artificial tadpole-like micromotor, which is fabricated through the electrospinning technique. By incorporating functional materials onto its surface or within its body, the resulting tadpole-like micromotor can not only move autonomously in an aqueous solution with a flexible tail, but also exhibit thermo- and magnetic responsive properties. Electronic supplementary information (ESI) available: Experimental section, Fig. S1-S3 and Video S1-S4. See DOI: 10.1039/c4nr06621a

Warm vegetarians? Heat waves and diet shifts in tadpoles.

PubMed

Carreira, B M; Segurado, P; Orizaola, G; Gonçalves, N; Pinto, V; Laurila, A; Rebelo, R

2016-11-01

Temperature can play an important role in determining the feeding preferences of ectotherms. In light of the warmer temperatures arising with the current climatic changes, omnivorous ectotherms may perform diet shifts toward higher herbivory to optimize energetic intake. Such diet shifts may also occur during heat waves, which are projected to become more frequent, intense, and longer lasting in the future. Here, we investigated how heat waves of different duration affect feeding preferences in omnivorous anuran tadpoles and how these choices affect larval life history. In laboratory experiments, we fed tadpoles of three species on animal, plant, or mixed diet and exposed them to short heat waves (similar to the heat waves these species experience currently) or long heat waves (predicted to increase under climate change). We estimated the dietary choices of tadpoles fed on the mixed diet using stable isotopes and recorded tadpole survival and growth, larval period, and mass at metamorphosis. Tadpole feeding preferences were associated with their thermal background, with herbivory increasing with breeding temperature in nature. Patterns in survival, growth, and development generally support decreased efficiency of carnivorous diets and increased efficiency or higher relative quality of herbivorous diets at higher temperatures. All three species increased herbivory in at least one of the heat wave treatments, but the responses varied among species. Diet shifts toward higher herbivory were maladaptive in one species, but beneficial in the other two. Higher herbivory in omnivorous ectotherms under warmer temperatures may impact species differently and further contribute to changes in the structure and function of freshwater environments. © 2016 by the Ecological Society of America.

Effects of lead-contaminated sediment on Rana sphenocephala tadpoles.

PubMed

Sparling, Donald W; Krest, Sherry; Ortiz-Santaliestra, Manuel

2006-10-01

We exposed larval southern leopard frogs (Rana sphenocephala) to lead-contaminated sediments to determine the lethal and sublethal effects of this metal. Tadpoles were laboratory-raised from early free-swimming stage through metamorphosis at lead concentrations of 45, 75, 180, 540, 2360, 3940, 5520, and 7580 mg/kg dry weight in sediment. Corresponding pore water lead concentrations were 123, 227, 589, 1833, 8121, 13,579, 19,038, and 24,427 microg/L. Tadpoles exposed to lead concentrations in sediment of 3940 mg/kg or higher died within 2 to 5 days of exposure. At lower concentrations, mortality through metamorphosis ranged from 3.5% at 45 mg/kg lead to 37% at 2360 mg/kg lead in sediment. The LC50 value for lead in sediment was 3728 mg/kg (95% CI = 1315 to 72,847 mg/kg), which corresponded to 12,539 microg/L lead in pore water (95% CI = 4000 to 35,200 microg/L). Early growth and development were depressed at 2,360 mg/kg lead in sediment (8100 microg/L in pore water) but differences were not evident by the time of metamorphosis. The most obvious effect of lead was its pronounced influence on skeletal development. Whereas tadpoles at 45 mg/kg lead in sediment did not display permanent abnormalities, skeletal malformations increased in frequency and severity at all higher lead concentrations. By 2360 mg/kg, 100% of surviving metamorphs displayed severe spinal problems, reduced femur and humerus lengths, deformed digits, and other bone malformations. Lead concentrations in tissues correlated positively with sediment and pore water concentrations.

Effects of lead-contaminated sediment on Rana sphenocephala tadpoles

USGS Publications Warehouse

Sparling, D.W.; Krest, S.K.; Ortiz-Santaliestra, M.

2006-01-01

We exposed larval southern leopard frogs (Rana sphenocephala) to lead-contaminated sediments to determine the lethal and sublethal effects of this metal. Tadpoles were laboratory-raised from early free-swimming stage through metamorphosis at lead concentrations of 45, 75, 180, 540, 2360, 3940, 5520, and 7580 mg/kg dry weight in sediment. Corresponding pore water lead concentrations were 123, 227, 589, 1833, 8121, 13,579, 19,038, and 24,427 ug/L. Tadpoles exposed to lead concentrations in sediment of 3940 mg/kg or higher died within 2 to 5 days of exposure. At lower concentrations, mortality through metamorphosis ranged from 3.5% at 45 mg/kg lead to 37% at 2360 mg/kg lead in sediment. The LC50 value for lead in sediment was 3728 mg/kg (95% CI=1315 to 72,847 mg/kg), which corresponded to 12,539 ug/L lead in pore water (95% CI= 4000 to 35,200 ug/L). Early growth and development were depressed at 2,360 mg/kg lead in sediment (8100 ug/L in pore water) but differences were not evident by the time of metamorphosis. The most obvious effect of lead was its pronounced influence on skeletal development. Whereas tadpoles at 45 mg/kg lead in sediment did not display permanent abnormalities, skeletal malformations increased in frequency and severity at all higher lead concentrations. By 2360 mg/kg, 100% of surviving metamorphs displayed severe spinal problems, reduced femur and humerus lengths, deformed digits, and other bone malformations. Lead concentrations in tissues correlated positively with sediment and pore water concentrations.

The interactive effects of UV-B and insecticide exposure on tadpole survival, growth and development

USGS Publications Warehouse

Bridges, Christine M.; Boone, Michelle D.

2003-01-01

Because declines within amphibian populations can seldom be attributed to a single cause, it is important to focus on multiple stressors, both natural and anthropogenic. Variables such as UV-B radiation and chemical contamination can interact with one another in ways that might not be predicted from single-factor studies. We exposed southern leopard frog (Rana sphenocephala) tadpoles to the insecticide carbaryl and varying intensities of UV-B radiation in artificial ponds and examined their effects on survival, size at metamorphosis, and the duration of the larval period. Tadpole survival to metamorphosis was positively influenced by UV-B intensity. Tadpoles in ponds exposed to carbaryl contained over three times more algae and yielded larger metamorphs than control ponds. Although previous laboratory studies have indicated carbaryl becomes more toxic in the presence of UV-B, we did not find such an effect, perhaps because of the protection afforded by dissolved organic carbon within the ponds. Our research emphasizes the importance of conducting field studies to more accurately predict what occurs under a natural setting. Published by Elsevier Science Ltd.

Exposures to estradiol, ethinylestradiol and octylphenol affect survival and growth of Rana pipiens and Rana sylvatica tadpoles.

PubMed

Hogan, Natacha S; Lean, David R S; Trudeau, Vance L

2006-08-01

Endocrine disrupting compounds (EDCs) are often detected in the aquatic environment and can negatively affect the health of wildlife populations. However, little is known about the sensitivity of native amphibians to EDCs. Wood frogs (Rana sylvatica) and Northern leopard frogs (Rana pipiens) were exposed to three estrogenic EDCs: estradiol (E2), ethinylestradiol (EE2), and 4-tert-octylphenol (OP). In addition, R. pipiens were exposed during two developmental stages (Gosner stages 26 and 36) to examine life-stage differences in sensitivity. Tadpoles were exposed for 2 wk to 8 nominal concentrations (0.25 microM-10 microM) of each compound. Individual mortality was recorded during the exposure period, while body weight was measured at the end of 2 wk. LC50 values were calculated, and differences in body weight between vehicle control and exposed groups were assessed. Rank order toxicity of the compounds for both R. pipiens stages and both species was OP > EE2 > E2. Gosner stage 26 tadpoles were more sensitive (LC50: E2 [5.57 microM], EE2 [3.01 microM], OP [1.36 microM]) to all three compounds when compared to stage 36 tadpoles (LC50: E2 [>10 microM], EE2 [4.17 microM], OP [2.80 microM]). Interspecies comparisons revealed R. sylvatica tadpoles (LC50: E2 [2.50 microM], EE2 [1.89 microM], OP [0.74 microM]) as being more sensitive to the three compounds than R. pipiens (LC50: E2 [4.56 microM], EE2 [2.75 microM], OP [1.42 microM]). Xenoestrogen exposure also affected tadpole body weight which may have long-term adverse effects on the rate of metamorphosis. These results provide toxicological data needed for assessing sublethal effects of estrogenic compounds on amphibian development and suggest that environmental levels of OP may pose a serious risk to the health of amphibian populations.

Overwintering tadpoles and loss of fitness correlates in Polypedates braueri tadpoles that use artificial pools in a lowland agroecosystem

USGS Publications Warehouse

Hsu, Juei-Ling; Kam, Yeong-Choy; Fellers, Gary M.

2012-01-01

We studied growth, development, and metamorphic traits of Polypedates braueri tadpoles in Taiwan to elucidate the cause of tadpole overwintering in man-made water containers in lowland orchards on the Bagua Terrace. Polypedates braueri bred from March to August, but tadpoles were present year round. Laboratory experiments demonstrated that tadpole overwintering was facultative; low temperatures and limited food retarded both growth and development, resulting in overwintering in the tadpole stage. Tadpoles at the lowest experimental temperature (15°C) never reached metamorphosis. A field experiment demonstrated that 78, 28, and 4% of tadpoles raised in high, medium, and low food regimes, respectively, metamorphosed before the onset of winter. Tadpoles that did not metamorphose by fall continued to grow slowly and either metamorphosed during the winter or the following spring. These findings indicate that food availability plays a key role in inducing overwintering in tadpoles. Jumping performance of metamorphs was positively correlated with food regimes, but body lipid content was significantly higher in metamorphs raised with either low or high food regimes than in those with medium levels of food. Overwintering by P. braueritadpoles has not been previously reported; however, agricultural activities have created new breeding habitats (i.e., man-made bodies of water), some of which are sufficiently food-limited that tadpoles overwinter to complete development and metamorphosis. An understanding of the survivorship, life history traits, and physiology of these frogs is needed to shed light on how man-made breeding sites affect the population dynamics of native frog populations.

Sodium perchlorate disrupts development and affects metamorphosis- and growth-related gene expression in tadpoles of the wood frog (Lithobates sylvaticus).

PubMed

Bulaeva, Elizabeth; Lanctôt, Chantal; Reynolds, Leslie; Trudeau, Vance L; Navarro-Martín, Laia

2015-10-01

Numerous endocrine disrupting chemicals can affect the growth and development of amphibians. We investigated the effects of a targeted disruption of the endocrine axes modulating development and somatic growth. Wood frog (Lithobates sylvaticus) tadpoles were exposed for 2weeks (from developmental Gosner stage (Gs) 25 to Gs30) to sodium perchlorate (SP, thyroid inhibitor, 14mg/L), estradiol (E2, known to alter growth and development, 200nM) and a reduced feeding regime (RF, to affect growth and development in a chemically-independent manner). All treatments experienced developmental delay, and animals exposed to SP or subjected to RF respectively reached metamorphic climax (Gs42) approximately 11(±3) and 17(±3) days later than controls. At Gs42, only SP-treated animals showed increased weight and snout-vent length (P<0.05) relative to controls. Tadpoles treated with SP had 10-times higher levels of liver igf1 mRNA after 4days of exposure (Gs28) compared to controls. Tadpoles in the RF treatment expressed 6-times lower levels of liver igf1 mRNA and 2-times higher liver igf1r mRNA (P<0.05) at Gs30. Tadpoles treated with E2 exhibited similar developmental and growth patterns as controls, but had increased liver igf1 mRNA levels at Gs28, and tail igf1r at Gs42. Effects on tail trβ mRNA levels were detected in SP-treated tadpoles at Gs42, 40days post-exposure, suggesting that the chemical inhibition of thyroid hormone production early in development can have long-lasting effects. The growth effects observed in the SP-exposed animals suggest a relationship between TH-dependent development and somatic growth in L. sylvaticus tadpoles. Copyright © 2015 Elsevier Inc. All rights reserved.

Tadpole-like artificial micromotor.

PubMed

Liu, Limei; Liu, Mei; Su, Yajun; Dong, Yonggang; Zhou, Wei; Zhang, Lina; Zhang, Hui; Dong, Bin; Chi, Lifeng

2015-02-14

We describe a polymer-based artificial tadpole-like micromotor, which is fabricated through the electrospinning technique. By incorporating functional materials onto its surface or within its body, the resulting tadpole-like micromotor can not only move autonomously in an aqueous solution with a flexible tail, but also exhibit thermo- and magnetic responsive properties.

Opposing Patterns of Seasonal Change in Functional and Phylogenetic Diversity of Tadpole Assemblages

PubMed Central

Strauß, Axel; Guilhaumon, François; Randrianiaina, Roger Daniel; Wollenberg Valero, Katharina C.; Vences, Miguel; Glos, Julian

2016-01-01

Assemblages that are exposed to recurring temporal environmental changes can show changes in their ecological properties. These can be expressed by differences in diversity and assembly rules. Both can be identified using two measures of diversity: functional (FD) and phylogenetic diversity (PD). Frog communities are understudied in this regard, especially during the tadpole life stage. We utilised tadpole assemblages from Madagascan rainforest streams to test predictions of seasonal changes on diversity and assemblage composition and on diversity measures. From the warm-wet to the cool-dry season, species richness (SR) of tadpole assemblages decreased. Also FD and PD decreased, but FD less and PD more than expected by chance. During the dry season, tadpole assemblages were characterised by functional redundancy (among assemblages—with increasing SR), high FD (compared to a null model), and low PD (phylogenetic clustering; compared to a null model). Although mutually contradictory at first glance, these results indicate competition as tadpole community assembly driving force. This is true during the limiting cool-dry season but not during the more suitable warm-wet season. We thereby show that assembly rules can strongly depend on season, that comparing FD and PD can reveal such forces, that FD and PD are not interchangeable, and that conclusions on assembly rules based on FD alone are critical. PMID:27014867

Differential sensitivity to the antifouling chemical medetomidine between wood frog and American toad tadpoles with evidence for low-dose stimulation and high-dose inhibition of metamorphosis.

PubMed

Fong, Peter P; Lambert, Olivia J; Hoagland, Margot L; Kurtz, Emily R

2018-05-05

Antifouling chemicals are legacy contaminants in aquatic ecosystems. Previous experiments have shown that a 14-day exposure to the antifouling chemical medetomidine delays metamorphosis and reduces body mass in wood frog tadpoles. In the present study, we exposed wood frog tadpoles to medetomidine for 3, 7, and 10 days at 100 nM, 1 μM, and 10 μM. We also exposed American toad tadpoles to medetomidine for 3 days at four concentrations (10 nM, 100 nM, 1 μM, and 10 μM) in static renewal experiments. In each experiment, we measured growth, frequency and time to metamorphosis, and mass at metamorphosis. In both species, medetomidine significantly slowed development as measured by the Gosner stage. After 34 days in culture, wood frog tadpoles exposed to 1 and 10 μM medetomidine for as few as 3 days were significantly less developed compared to controls. Toads exposed to 1 μM medetomidine for 3 days were also significantly less developed on day 27, but by day 34, there was no difference from controls. For wood frogs, medetomidine significantly affected time to metamorphosis with a trend for tadpoles at lower concentrations metamorphosing sooner than those at higher concentrations. While medetomidine affected time to metamorphosis in wood frogs, it did not affect fresh mass, dry mass, or mortality compared to controls. Wood frog tadpoles that did not metamorphose after over 90 days in culture were more frequent in high-concentration groups than in the control. In toads, 10 μM medetomidine was 100% lethal within 23 days, but at the same concentration and duration, no wood frog tadpoles died. Lower concentrations were also significantly lethal to toads compared to controls, but tadpoles that survived in 10 and 100 nM metamorphosed sooner than those in 1 μM. Fresh mass of toad tadpoles exposed to 1 μm was significantly smaller at metamorphosis compared to that of controls. Medetomidine also affected the behavior of tadpoles. In toads, medetomidine

Differential uptake of gold nanoparticles by 2 species of tadpole, the wood frog (Lithobates sylvaticus) and the bullfrog (Lithobates catesbeianus).

PubMed

Thompson, Lucas B; Carfagno, Gerardo L F; Andresen, Kurt; Sitton, Andrea J; Bury, Taylor; Lee, Laura L; Lerner, Kevin T; Fong, Peter P

2017-12-01

Engineered nanoparticles are aquatic contaminants of emerging concern that exert ecotoxicological effects on a wide variety of organisms. We exposed cetyltrimethylammonium bromide-capped spherical gold nanoparticles to wood frog and bullfrog tadpoles with conspecifics and in combination with the other species continuously for 21 d, then measured uptake and localization of gold. Wood frog tadpoles alone and in combination with bullfrog tadpoles took up significantly more gold than bullfrogs. Bullfrog tadpoles in combination with wood frogs took up significantly more gold than controls. The rank order of weight-normalized gold uptake was wood frogs in combination > wood frogs alone > bullfrogs in combination > bullfrogs alone > controls. In all gold-exposed groups of tadpoles, gold was concentrated in the anterior region compared with the posterior region of the body. The concentration of gold nanoparticles in the anterior region of wood frogs both alone and in combination with bullfrogs was significantly higher than the corresponding posterior regions. We also measured depuration time of gold in wood frogs. After 21 d in a solution of gold nanoparticles, tadpoles lost >83% of internalized gold when placed in gold-free water for 5 d. After 10 d in gold-free water, tadpoles lost 94% of their gold. After 15 d, gold concentrations were below the level of detection. Our finding of differential uptake between closely related species living in similar habitats with overlapping geographical distributions argues against generalizing toxicological effects of nanoparticles for a large group of organisms based on measurements in only one species. Environ Toxicol Chem 2017;36:3351-3358. © 2017 SETAC. © 2017 SETAC.

Interactions between freshwater snails and tadpoles: competition and facilitation.

PubMed

Brönmark, Christer; Rundle, Simon D; Erlandsson, Ann

1991-06-01

Freshwater snails and anuran tadpoles have been suggested to have their highest population densities in ponds of intermediate size where abiotic disturbance (e.g. desiccation) is low and large predators absent. Both snails and tadpoles feed on periphytic algae and, thus, there should be a large potential for competitive interactions to occur between these two distantly related taxa. In a field experiment we examined the relative strength of competition between two closely related snail species, Lymnaea stagnalis and L. peregra, and between L. stagnalis and tadpoles of the common frog, Rana temporaria. Snail growth and egg production and tadpole size at and time to metamorphosis were determined. Effects on the common food source, periphyton, were monitored with the aid of artificial substrates. Periphyton dry weight was dramatically reduced in the presence of snails and/or tadpoles. There were no competitive effects on growth or egg production of the two snail species when they were coexisting. Mortality of L. peregra was high (95%) after reproduction, but independent of treatment. Growth of L. stagnalis was reduced only at the highest tadpole densities, whereas egg production was reduced both by intraspecific competition and by competition with tadpoles. Differences in egg production were retained after tadpole metamorphosis. Tadpole larval period increased, weight of metamorphosing frogs decreased and growth rate was reduced as a function of increasing tadpole density. However, contrary to expectation, snails had a positive effect on tadpole larval period, weight and growth rate. Further, in experimental containers without snails there was a dense growth of the filamentous green alga Cladophora sp. We suggest that the facilitative effects of snails on tadpoles are due to an "indirect mutualistic" mechanism, involving competition between food sources of different quality (microalgae and Cladophora sp.) and tadpoles being competitively dominant over snails for the

Exposure of xenopus laevis tadpoles to cadmium reveals concentration-dependent bimodal effects on growth and monotonic effects on development and thyroid gland activity

USGS Publications Warehouse

Sharma, Bibek; Patino, R.

2008-01-01

Xenopus laevis were exposed to 0-855 ??g cadmium (Cd)/l (measured concentrations) in FETAX medium from fertilization to 47 days postfertilization. Measurements included embryonic survival and, at 47 days, tadpole survival, snout-vent length, tail length, total length, hindlimb length, weight, Nieuwkoop-Faber (NF) stage of development, initiation of metamorphic climax (??? NF 58), and thyroid follicle cell height. Embryonic and larval survival were unaffected by Cd. Relative to control tadpoles, reduced tail and total length were observed at 0.1- 8 and at 855 ??g Cd/l; and reduced snout-vent length, hindlimb length, and weight were observed at 0.1-1 and at 855 ??g Cd/l. Mean stage of development and rate of initiation of climax were unaffected by Cd at 0-84 ??g/l; however, none of the tadpoles exposed to 855 ??g Cd/l progressed beyond mid-premetamorphosis (NF 51). Thyroid glands with fully formed follicles were observed in all tadpoles ??? NF 49 examined. Follicle cell height was unaffected by Cd at 0-84 ??g/l but it was reduced at 855 ??g/l; in the latter, cell height was reduced even when compared with NF 49-51 tadpoles pooled from the 0 to 84 ??g Cd/l groups. In conclusion, (1) Cd affected tadpole growth in a bimodal pattern with the first and second inhibitory modes at concentrations below and above 84 ??g Cd/l, respectively; (2) exposure to high Cd concentrations (855 ??g/l) reduced thyroid activity and arrested tadpole development at mid-premetamorphosis; and (3) unlike its effect on growth, Cd inhibited tadpole development and thyroid function in a seemingly monotonic pattern.

Uptake and effects on detoxication enzymes of cypermethrin in embryos and tadpoles of amphibians.

PubMed

Greulich, K; Pflugmacher, S

2004-11-01

A number of factors have been suggested for recently observed amphibian decreases, and one potential factor is pesticide exposure. We studied the uptake and effects of environmentally relevant concentrations of the pyrethroid insecticide cypermethrin on two different amphibian species, Bombina variegata and Rana arvalis. The uptake from water of 14C-labeled cypermethrin (0.4 microg/L) by eggs and tadpoles of B. variegata was investigated. After 24 hours of exposure, 153.9 ng cypermethrin/g fresh weight were found in embryos, thus indicating that the jelly mass of the eggs does not act as a sufficient physical barrier to protect embryos from exposure to this compound. Uptake of cypermethrin into tadpoles of both species and in all exposed individuals caused dose-dependent deformities; behavioral abnormalities such as twisting, writhing, and coordinated swimming; and mortality. In tadpoles of B. variegata and R. arvalis, the activity of microsomal and cytosolic glutathione S-transferase (mGST and sGST, respectively) were measured after treatment with cypermethrin. Activities of both GST systems increased significantly with increasing duration and concentration of cypermethrin exposure, with the reaction seeming stronger in B. variegata than in R. arvalis tadpoles. Alpha-cypermethrin--a racemic mixture of two cis isomers of cypermethrin--induced a stronger enzymatic response in the cytosolic fraction of R. arvalis tadpoles than cypermethrin at the same concentration. The observed physical and behavioral abnormities caused by environmentally relevant concentrations of cypermethrin indicate that despite detoxication of the chemical via GST-system contamination of ponds by cypermethrin could result in adverse effects on the development of amphibian embryos and tadpoles.

Predator-induced defenses in tadpoles confound body stoichiometry predictions of the general stress paradigm.

PubMed

Costello, David M; Michel, Matt J

2013-10-01

Predation is known to have both direct and indirect effects on nutrient cycling in terrestrial and aquatic ecosystems, and the general stress paradigm (GSP) has been promoted as a theory for describing predator-mediated indirect effects on nutrient cycling. The GSP predicts that prey exposed to predators will produce glucocorticosteroids, which have a host of physiological effects including gluconeogenesis, increased respiration, excretion of N and P, and increases in body C:N. We tested the nutrient predictions of the GSP using anuran larvae, which exhibit morphological defenses in addition to behavioral defenses for which the GSP was conceived. Genetically similar Hyla versicolor tadpoles were placed in mesocosms either in the presence or absence of a fed predator (Dytiscus verticalis), and after two weeks, tadpoles exposed to predators exhibited strong induced defenses with large, tubular bodies, larger tails, and reduced activity. Tadpole body %C and N:P increased with no change in C:N, which is contrary to expectations from the GSP. Statistical models suggested that changes in body morphology (e.g., tail muscle width) rather than behavioral defenses (i.e., reduced activity) were most likely responsible for predator-mediated differences in body stoichiometry. This study suggests that strong morphological defenses may overwhelm or counteract the nutrient predictions of the GSP.

Optomotor behaviour in Xenopus laevis tadpoles as a measure of the effect of gravity on visual and vestibular neural integration

NASA Technical Reports Server (NTRS)

Pronych, S. P.; Souza, K. A.; Neff, A. W.; Wassersug, R. J.

1996-01-01

The ability of aquatic vertebrates to maintain their position requires integration of visual and vestibular sensory information. To understand better how aquatic animals integrate such information, we measured the optomotor behaviour of Xenopus laevis tadpoles raised in growth chambers in microgravity (< 10(-3)g), normal gravity (1 g), hypergravity (3 g) and on a slowly rotating clinostat (simulated microgravity). The goal of this research was to determine how development in an altered gravitational force field affects the visual- and vestibular-dependent behaviour of tadpoles. This research represents the first time that the optomotor behaviour of an organism raised from fertilization in microgravity has been tested. Significant differences were observed in the optomotor behaviour among the four gravity treatments. When first exposed to normal gravity, the microgravity-raised tadpoles exhibited the strongest (or most positive) optomotor behaviour, while the 3 g centrifuge tadpoles showed no optomotor response. Some abnormal behaviours (such as erratic swimming, lying motionless and abnormal swimming posture) were observed in the tadpoles raised in altered gravity on the initial day of testing. One day later, the tadpoles raised in hypergravity did not differ significantly in their optomotor behaviour from control tadpoles raised in normal gravity. However, tadpoles raised in microgravity still displayed an exaggerated optomotor response. One week after the tadpoles had been introduced to normal gravity, there was no longer a significant difference in optomotor behaviour among the different gravity treatments. This convergence of optomotor behaviour by tadpoles from the different treatment reflects the acclimation of their vestibular systems to normal gravity.

Salinity acclimation enhances salinity tolerance in tadpoles living in brackish water through increased Na⁺ , K⁺ -ATPase expression.

PubMed

Wu, Chi-Shiun; Yang, Wen-Kai; Lee, Tsung-Han; Gomez-Mestre, Ivan; Kam, Yeong-Choy

2014-01-01

Amphibians are highly susceptible to osmotic stress but, nonetheless, some species can adapt locally to withstand moderately high levels of salinity. Maintaining the homeostasis of body fluids by efficient osmoregulation is thus critical for larval survival in saline environments. We studied the role of acclimation in increased physiological tolerance to elevated water salinity in the Indian rice frog (Fejervarya limnocharis) tadpoles exposed to brackish water. We quantified the effects of salinity acclimation on tadpole survival, osmolality, water content, and gill Na⁺ , K⁺ -ATPase (NKA) expression. Tadpoles did not survive over 12 hr if directly transferred to 11 ppt (parts per thousand) whereas tadpoles previously acclimated for 48 hr in 7  ppt survived at least 48 hr. We reared tadpoles in 3 ppt and then we transferred them to one of (a) 3 ppt, (b) 11  ppt, and (c) 7  ppt for 48 hr and then 11 ppt. In the first 6 hr after transfer to 11 ppt, tadpole osmolality sharply increased and tadpole water content decreased. Tadpoles pre-acclimated for 48 hr in 7 ppt were able to maintain lower and more stable osmolality within the first 3 hr after transfer. These tadpoles initially lost water content, but over the next 6 hr gradually regained water and stabilized. In addition, they had a higher relative abundance of NKA proteins than tadpoles in other treatments. Pre-acclimation to 7 ppt for 48 hr was hence sufficient to activate NKA expression, resulting in increased survivorship and reduced dehydration upon later transfer to 11 ppt. J © 2013 Wiley Periodicals, Inc.

Effects of a glyphosate-based herbicide and predation threat on the behaviour of agile frog tadpoles.

PubMed

Mikó, Zsanett; Ujszegi, János; Gál, Zoltán; Hettyey, Attila

2017-06-01

The widespread application of pesticides emphasises the importance of understanding the impacts of these chemicals on natural communities. The most commonly applied broad-spectrum herbicides in the world are glyphosate-based herbicides, which have been suggested to induce significant behavioural changes in non-target organisms even at low environmental concentrations. To scrutinize the behavioural effects of herbicide-exposure we exposed agile frog (Rana dalmatina) tadpoles in an outdoor mesocosm experiment to three concentrations of a glyphosate-based herbicide (0, 2 and 6.5mg acid equivalent (a.e.) / L). To assess whether anti-predator behaviour is affected by the pesticide, we combined all levels of herbicide-exposure with three predator treatments (no predator, caged Aeshna cyanea dragonfly larvae or Lissotriton vulgaris newt adults) in a full factorial design. We observed hiding, activity, proximity to the predator cage and vertical position of tadpoles. We found that at the higher herbicide concentration tadpoles decreased their activity and more tadpoles were hiding, and at least at the lower concentration their vertical position was closer to the water surface than in tadpoles of the control treatment. Tadpoles also decreased their activity in the presence of dragonfly larvae, but did not hide more in response to either predator, nor did tadpoles avoid predators spatially. Further, exposure to the herbicide did not significantly influence behavioural responses to predation threat. Our study documents a definite influence of glyphosate-based herbicides on the behaviour of agile frog tadpoles and indicates that some of these changes are similar to those induced by dangerous predators. This may suggest that the underlying physiological mechanisms or the adaptive value of behavioural changes may similar. Copyright © 2017 Elsevier Inc. All rights reserved.

Study of aggregative behavior of Rhinophrynus dorsalis tadpoles: design and analysis

USGS Publications Warehouse

Foster, M.S.; McDiarmid, R.W.

1982-01-01

We conducted experiments using the apparatus and design followed by Wassersug and Hessler (1971) and Wassersug (1973) to test the aggregative behavior of tadpoles of Rhinophrynus dorsalis in response to visual and olfactory stimuli. Results neither supported nor refuted the hypothesis that either stimulus is used as a mechanism for school formation. The exercise did lead to doubts about the experimental design. Some ambiguity resulted from the fact that the significance of the results depended upon the way in which the data were analyzed. Several alternative methods were considered. We also observed tadpoles reared in isolation to determine the effect of prior social conditioning on aggregative behavior. Isolates grew less than group-reared animals, were less active, and exhibited a strong avoidance reaction when subsequently exposed to conspecifics.

LOCAL TADPOLE GALAXIES: DYNAMICS AND METALLICITY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanchez Almeida, J.; Munoz-Tunon, C.; Mendez-Abreu, J.

2013-04-10

Tadpole galaxies, with a bright peripheral clump on a faint tail, are morphological types unusual in the nearby universe but very common early on. Low mass local tadpoles were identified and studied photometrically in a previous work, which we complete here analyzing their chemical and dynamical properties. We measure H{alpha} velocity curves of seven local tadpoles, representing 50% of the initial sample. Five of them show evidence for rotation ({approx}70%), and a sixth target hints at it. Often the center of rotation is spatially offset with respect to the tadpole head (three out of five cases). The size and velocitymore » dispersion of the heads are typical of giant H II regions, and three of them yield dynamical masses in fair agreement with their stellar masses as inferred from photometry. In four cases the velocity dispersion at the head is reduced with respect to its immediate surroundings. The oxygen metallicity estimated from [N II] {lambda}6583/H{alpha} often shows significant spatial variations across the galaxies ({approx}0.5 dex), being smallest at the head and larger elsewhere. The resulting chemical abundance gradients are opposite to the ones observed in local spirals, but agrees with disk galaxies at high redshift. We interpret the metallicity variation as a sign of external gas accretion (cold-flows) onto the head of the tadpole. The galaxies are low-metallicity outliers of the mass-metallicity relationship. In particular, two of the tadpole heads are extremely metal poor, with a metallicity smaller than a tenth of the solar value. These two targets are also very young (ages smaller than 5 Myr). All these results combined are consistent with the local tadpole galaxies being disks in early stages of assembling, with their star formation sustained by accretion of external metal-poor gas.« less

Caging, but not air deprivation, slows tadpole growth and development in the amphibian Xenopus laevis.

PubMed

Rose, Christopher S

2014-08-01

Xenopus laevis tadpoles raised in submerged cages in normoxic water develop more slowly than tadpoles raised with access to air. This study distinguishes between the effects of being caged and being deprived access to air on development and growth. Tadpoles were raised in high and low density control tanks and in cages in the same tank that were either completely submerged or with the top exposed to air. Experiments were repeated with the cages in different positions relative to the air stones and with and without the water flow from air stones supplemented with a pump. Whereas caging tadpoles has a large effect on their development and growth, additionally depriving them of air has a small effect and this effect can be removed by optimizing water flow through the cage. The effect of caging, though significant in this study, is small compared to the variation in growth and developmental rates that is commonly encountered within and among controls in lab studies. Caging effects can also be diminished by optimizing rearing conditions and/or having exceptionally vigorous tadpoles. The effects of air deprivation and caging thus pose less of a problem for experimenting on air-deprived (AD) and air-restored Xenopus tadpoles than their inherent variability in growth and developmental rates and their susceptibility to growth and developmental arrest. Further, the effect of air deprivation in this air-breathing amphibian does not pose a conflict with evolutionary hypotheses for lung loss involving lengthening of the larval period and delay in the onset of air breathing. © 2014 Wiley Periodicals, Inc.

Toxic and genotoxic effects of the imazethapyr-based herbicide formulation Pivot H® on montevideo tree frog Hypsiboas pulchellus tadpoles (Anura, Hylidae).

PubMed

Pérez-Iglesias, J M; Soloneski, S; Nikoloff, N; Natale, G S; Larramendy, M L

2015-09-01

Acute lethal and sublethal toxicity of the imidazolinone imazethapyr (IMZT)-based commercial formulation herbicide Pivot H® (10.59% IMZT) was evaluated on Hypsiboas pulchellus tadpoles. Whereas mortality was used as the end point for lethality, frequency of micronuclei (MNs) and other nuclear abnormalities as well as DNA single-strand breaks evaluated by the single cell gel electrophoresis assay were employed to test genotoxicity. Behavioral, growth, developmental, and morphological abnormalities were also employed as sublethal end points. Mortality studies revealed equivalent LC50 (96h) values of 1.49mg/L (confidence limit, 1.09-1.63) and 1.55mg/L (confidence limit, 1.51-1.60) IMZT for Gosner stage (GS) 25 and GS36, respectively. Behavioral changes, i.e., irregular swimming and immobility, as well as a decreased frequency of keratodonts were observed. The herbicide increased the frequency of MNs in circulating erythrocytes of tadpoles exposed for 48h to the highest concentration assayed (1.17mg/L). However, regardless of the concentration of the herbicide assayed, an enhanced frequency of MNs was observed in tadpoles exposed for 96h. The herbicide was able to induce other nuclear abnormalities, i.e., blebbed and notched nuclei, only when tadpoles were exposed for 96h. In addition, we observed that exposure to IMZT within the 0.39-1.17mg/L range increased the genetic damage index in treatments lasting for both 48 and 96h. This study represents the first evidence of acute lethal and sublethal effects exerted by IMZT on amphibians. Finally, our findings highlight the properties of this herbicide that jeopardize nontarget living species exposed to IMZT. Copyright © 2015 Elsevier Inc. All rights reserved.

Effects of environmental temperature on the gut microbial communities of tadpoles.

PubMed

Kohl, Kevin D; Yahn, Jeremiah

2016-05-01

Numerous studies have investigated the effects of diet, phylogeny and immune status on the gut microbial communities of animals. Most of these studies are conducted on endotherms, especially mammals, which maintain constant body temperature in the face of environmental temperature variability. However, the majority of animals and vertebrates are ectotherms, which often experience fluctuations in body temperature as a result of their environment. While there have been several studies investigating the gut microbial diversity of ectotherms, we lack an understanding of how environmental temperature affects these communities. Here, we used high-throughput sequencing to inventory the gut microbial communities of tadpoles exposed to cool (18°C) or warm (28°C) temperature treatments. We found that temperature significantly impacted the community structure and membership of the tadpole gut. Specifically, tadpoles in the warm treatment exhibited higher abundances of the phylum Planctomycetes and the genus Mycobacterium. These results may be due to the direct effects of temperature, or mediated through changes in host physiology. Given that environmental temperatures are expected to increase due to global climate change, understanding the effects of temperature on the diversity and function of gut microbial communities is critical. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

LOCAL TADPOLE GALAXIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elmegreen, Debra Meloy; Putko, Joseph; Dewberry, Janosz

2012-05-10

Tadpole galaxies have a giant star-forming region at the end of an elongated intensity distribution. Here we use Sloan Digital Sky Survey data to determine the ages, masses, and surface densities of the heads and tails in 14 local tadpoles selected from the Kiso and Michigan surveys of UV-bright galaxies, and we compare them to tadpoles previously studied in the Hubble Ultra Deep Field. The young stellar mass in the head scales linearly with rest-frame galaxy luminosity, ranging from {approx}10{sup 5} M{sub Sun} at galaxy absolute magnitude U = -13 mag to 10{sup 9} M{sub Sun} at U = -20more » mag. The corresponding head surface density increases from several M {sub Sun} pc{sup -2} locally to 10-100 M{sub Sun} pc{sup -2} at high redshift, and the star formation rate (SFR) per unit area in the head increases from {approx}0.01 M{sub Sun} yr{sup -1} kpc{sup -2} locally to {approx}1 M{sub Sun} yr{sup -1} kpc{sup -2} at high z. These local values are normal for star-forming regions, and the increases with redshift are consistent with other cosmological SFRs, most likely reflecting an increase in gas abundance. The tails in the local sample look like bulge-free galaxy disks. Their photometric ages decrease from several Gyr to several hundred Myr with increasing z, and their surface densities are more constant than the surface densities of the heads. The far-outer intensity profiles in the local sample are symmetric and exponential. We suggest that most local tadpoles are bulge-free galaxy disks with lopsided star formation, perhaps from environmental effects such as ram pressure or disk impacts, or from a Jeans length comparable to half the disk size.« less

Metal concentrations of tadpoles in experimental ponds

USGS Publications Warehouse

Sparling, D.W.; Lowe, T.P.

1996-01-01

Anuran tadpoles are found in a variety of habitats, many of which are acidified or have high ambient concentrations of metals from anthropogenic sources. A few studies that have been conducted on metals in tadpoles demonstrate that they can contain high concentrations of some metals but have not demonstrated clear relationships between ambient conditions and metal concentrations. This study examines the influence of soil, water treatment, amphibian species, and body portion analyzed on metal concentration in tadpoles. In northern cricket frogs, gray treefrogs, and green frogs, concentrations of Al and Fe exceeded I0000 g.g-1 and Mg and Mn exceeded 1000 g g-1. Body concentrations of Ba, Be, Fe, Mg, Mn, Ni, Pb, and Sr increased with soil concentrations. Acidification reduced body concentrations of Be and Sr, and pH correlated with Be, Mg, and Sr. Gray treefrogs had significantly lower concentrations of most metals compared to northern cricket frogs, possibly because of differences in microhabitats and soil ingestion. More than half of most metals was sequestered in the gut coil of green frog tadpoles, probably mixed with soil. Depending on bio-availability, many of the metals in gut coils and whole bodies of these tadpoles could be potentially toxic to predators.

Tadpoles of Early Breeding Amphibians are Negatively Affected by Leaf Litter From Invasive Chinese Tallow Trees

NASA Astrophysics Data System (ADS)

Leonard, N. E.

2005-05-01

As wetlands are invaded by Chinese tallow trees (Triadica sebifera), native trees are displaced and detrital inputs to amphibian breeding ponds are altered. I used a mesocosm experiment to examine the effect of Chinese tallow leaf litter on the survival to, size at, and time to metamorphosis of amphibian larvae. Fifty 1000-L cattle watering tanks were treated with 1500 g dry weight of one of five leaf litter treatments: Chinese tallow, laurel oak (Quercus laurifolia), water tupelo (Nyssa aquatica), slash pine (Pinus elliottii), or a 3:1:1:1 mixture. Each tank received 45 tadpoles of Pseudacris feriarum, Bufo terrestris, and Hyla cinerea in sequence according to their natural breeding phonologies. Every Pseudacris feriarum and Bufo terrestris tadpole exposed to Chinese tallow died prior to metamorphosis. Hyla cinerea survival in tanks with tallow-only was significantly lower than that observed for all other leaf treatments. Hyla cinerea tadpoles from tallow-only and mixed-leaf treatments were larger at metamorphosis and transformed faster than those in tanks with native leaves only. These results suggest that Chinese tallow leaf litter may negatively affect tadpoles of early breeding frogs and that Chinese tallow invasion may change the structure of amphibian communities in temporary ponds.

Is Tadpole Pupil in an Adolescent Girl Caused by Denervation Hypersensitivity?

PubMed

Hansen, Jonas Kjeldbjerg; Møller, Hans Ulrik

2017-06-01

Tadpole pupil is a rarely encountered phenomenon caused by episodic, segmental iris dilator muscle spasm of short duration (2-15 minutes), occurring in clusters without a known precipitating factor. It has most commonly been described in women aged 28 to 48 years. A few hypotheses on pathogenesis have been discussed but none has been proved. Here, we present an adolescent girl with bilateral tadpole pupil that appeared during physical exercise. This is the first pediatric case of tadpole pupil, not caused by preceding surgery, to be published. Based on (1) this case in which tadpole pupil developed when the norepinephrine level rose during exercise, (2) the high ratio of patients with tadpole pupil who concurrently have or later develop Horner syndrome, in which denervation hypersensitivity is well described, (3) a previous report of a patient with both tadpole pupil and Horner syndrome who had denervation hypersensitivity on pharmacological testing, (4) a 29-year-old man with unilateral tadpole pupil induced by exercise, and (5) a 19-year-old man with bilateral tadpole pupil and possible autonomic neuropathy, we suggest denervation hypersensitivity as a probable pathogenic mechanism causing tadpole pupil. In addition, a suggestion for investigations to be performed in future pediatric cases is provided. Georg Thieme Verlag KG Stuttgart · New York.

Relations between conspecific density and effects of ultraviolet-b radiation on tadpole size in the striped marsh frog.

PubMed

Mitchell, Toby; Alton, Lesley A; White, Craig R; Franklin, Craig E

2012-12-01

Global increases in ultraviolet-B radiation (UVBR) associated with stratospheric ozone depletion are potentially contributing to the decline of numerous amphibian species around the world. Exposure to UVBR alone reduces survival and induces a range of sublethal effects in embryonic and larval amphibians. When additional environmental stressors are present, UVBR can have compounding negative effects. Thus, examination of the effects of UVBR in the absence of other stressors may substantially underestimate its potential to affect amphibians in natural habitats. We examined the independent and interactive effects of increased UVBR and high conspecific density would have embryonic and larval striped marsh frogs (Limnodynastes peronii). We exposed individuals to a factorial combination of low and high UVBR levels and low, medium, and high densities of striped marsh frog tadpoles. The response variables were time to hatching, hatching success, posthatch survival, burst-swimming performance of tadpoles (maximum instantaneous swim speed following an escape response), and size and morphology of tadpoles. Consistent with results of previous studies, we found that exposure to UVBR alone increased the time to hatching of embryos and reduced the burst-swimming performance and size of tadpoles. Similarly, increasing conspecific density increased the time to hatching of embryos and reduced the size of tadpoles, but had no effect on burst-swimming performance. The negative effect of UVBR on tadpole size was not apparent at high densities of tadpoles. This result suggests that tadpoles living at higher densities may invest relatively less energy in growth and thus have more energy to repair UVBR-induced damage. Lower densities of conspecifics increased the negative effects of UVBR on developing amphibians. Thus, low-density populations, which may include declining populations, may be particularly susceptible to the detrimental effects of increased UVBR and thus may be driven toward

Chronic Effects of Fluoride Exposure on Growth, Metamorphosis, and Skeleton Development in Bufo gargarizans Larvae.

PubMed

Chai, Lihong; Wang, Hongyuan; Zhao, Hongfeng; Dong, Suiming

2017-04-01

Bufo gargarizans tadpoles were chronically exposed to waterborne fluoride at measured concentrations ranging from 0.4 to 61.2 mg F - /L for 70 days from Gosner stage 26 to completion of metamorphosis. The chronic exposure caused a concentration-dependent mortality in all tested fluoride concentrations. Total length, snout-to-vent length (SVL), body mass, and developmental stage of tadpoles were significantly inhibited at 42.6 mg F - /L. In addition, significant metamorphic delay and increase in size at completion of metamorphosis occurred after exposure to 19.8 mg F - /L. Moreover, 19.8 mg F - /L suppressed the bone mineralization of larvae at completion of metamorphosis. However, the bone mineralization could be enhanced by 4.1 mg F - /L. In conclusion, our results suggested that the presence of high concentrations of fluoride could increase mortality risk, delay metamorphosis, and suppress skeletal ossification in B. gargarizans larvae.

The phototoxic effects of fluoranthene on bullfrog tadpoles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walker, S.E.; Taylor, D.H.; Oris, J.T.

1995-12-31

The objective of this study was to determine the phototoxic effects of fluoranthene on bullfrog larvae by examining the relationship between median time to death and fluoranthene concentration and by examining the effects of short-term sublethal fluoranthene exposure on behavior and body condition. To determine the relationship between median time to death and fluoranthene concentration, tadpoles were exposed to either 0, 60, 80, 100 or 120 mg fluoranthene/L, and monitored for 144h under SUVR (40--50 mW/cm{sup 2} UVA, 4--6 mW/cm{sup 2} UVB). To examine the effects of fluoranthene on behavior and body condition, 20 tadpoles were exposed to either 0,more » 10, or 40 mg fluoranthene/L with simulated SUVR for either 48 or 96 h. At either 48 or 96 h ten individuals were removed and their locomotor activity was monitored and the body length and mass determined. Median time to death decreased with increased fluoranthene concentration and appears to do so in a linear fashion. Body condition was determined using a ratio index (mass/length{sup 3}) and a residual index was determined using the residuals of a regression of body length and body mass. Both exposure time and concentration affected both condition indices. Body burden was significantly affected at 10 mg fluoranthene/L. Exposure to fluoranthene for 48 h caused no significant effect on locomotor activity. However, at 96 h hyperactivity was noted in the highest fluoranthene exposure concentration. These results indicate that exposure to fluoranthene under environmentally realistic conditions can cause both lethal and sublethal effects on amphibian larvae.« less

Evaluation of avoidance behavior of tadpole madtoms (Noturus gyrinus) as a surrogate for the endangered northern madtom (Noturus stigmosus) in response to granular Bayluscide®

USGS Publications Warehouse

Boogaard, Michael A.; Erickson, Richard A.; Hubert, Terrance D.

2016-09-02

The vertical avoidance behavior of the tadpole madtom (Noturus gyrinus) exposed to environmentally relevant concentrations of the granular formulation of the lampricide Bayluscide® was evaluated. The lampricide formulation (3.2 percent active ingredient coated on a sand granule) is used to control larval sea lamprey populations in the Great Lakes. The tadpole madtom was chosen as a surrogate to the federally endangered northern madtom (Noturus stigmosus) based on similar life history characteristics and habitat requirements. Vertical avoidance of tadpole madtoms in response to the granular formulation was documented in clear Plexiglas columns (107 centimeters in height, 30.5 centimeters in diameter) for 1 hour after chemical application. Each avoidance trial produced data consisting of the number of tadpole madtoms avoiding the chemical at a given time. Based on the overall data, tadpole madtoms in treated columns were 11.7 times more likely to display avoidance compared to those in untreated controls. Results indicate that it is likely that northern madtoms will be able to detect and avoid Bayluscide® from granular applications if their response is similar to that of the tadpole madtom.

Biomarker analysis of American toad (Anaxyrus americanus) and grey tree frog (Hyla versicolor) tadpoles following exposure to atrazine.

PubMed

Snyder, Marcía N; Henderson, W Matthew; Glinski, Donna A; Purucker, S Thomas

2017-01-01

The objective of the current study was to use a biomarker-based approach to investigate the influence of atrazine exposure on American toad (Anaxyrus americanus) and grey tree frog (Hyla versicolor) tadpoles. Atrazine is one of the most frequently detected herbicides in environmental matrices throughout the United States. In surface waters, it has been found at concentrations from 0.04-2859μg/L and thus presents a likely exposure scenario for non-target species such as amphibians. Studies have examined the effect of atrazine on the metamorphic parameters of amphibians, however, the data are often contradictory. Gosner stage 22-24 tadpoles were exposed to 0 (control), 10, 50, 250 or 1250μg/L of atrazine for 48h. Endogenous polar metabolites were extracted and analyzed using gas chromatography coupled with mass spectrometry. Statistical analyses of the acquired spectra with machine learning classification models demonstrated identifiable changes in the metabolomic profiles between exposed and control tadpoles. Support vector machine models with recursive feature elimination created a more efficient, non-parametric data analysis and increased interpretability of metabolomic profiles. Biochemical fluxes observed in the exposed groups of both A. americanus and H. versicolor displayed perturbations in a number of classes of biological macromolecules including fatty acids, amino acids, purine nucleosides, pyrimidines, and mono- and di-saccharides. Metabolomic pathway analyses are consistent with findings of other studies demonstrating disruption of amino acid and energy metabolism from atrazine exposure to non-target species. Copyright © 2016. Published by Elsevier B.V.

An evaluation of population index and estimation techniques for tadpoles in desert pools

USGS Publications Warehouse

Jung, Robin E.; Dayton, Gage H.; Williamson, Stephen J.; Sauer, John R.; Droege, Sam

2002-01-01

Using visual (VI) and dip net indices (DI) and double-observer (DOE), removal (RE), and neutral red dye capture-recapture (CRE) estimates, we counted, estimated, and censused Couch's spadefoot (Scaphiopus couchii) and canyon treefrog (Hyla arenicolor) tadpole populations in Big Bend National Park, Texas. Initial dye experiments helped us determine appropriate dye concentrations and exposure times to use in mesocosm and field trials. The mesocosm study revealed higher tadpole detection rates, more accurate population estimates, and lower coefficients of variation among pools compared to those from the field study. In both mesocosm and field studies, CRE was the best method for estimating tadpole populations, followed by DOE and RE. In the field, RE, DI, and VI often underestimated populations in pools with higher tadpole numbers. DI improved with increased sampling. Larger pools supported larger tadpole populations, and tadpole detection rates in general decreased with increasing pool volume and surface area. Hence, pool size influenced bias in tadpole sampling. Across all techniques, tadpole detection rates differed among pools, indicating that sampling bias was inherent and techniques did not consistently sample the same proportion of tadpoles in each pool. Estimating bias (i.e., calculating detection rates) therefore was essential in assessing tadpole abundance. Unlike VI and DOE, DI, RE, and CRE could be used in turbid waters in which tadpoles are not visible. The tadpole population estimates we used accommodated differences in detection probabilities in simple desert pool environments but may not work in more complex habitats.

Effects of cadmium on growth, metamorphosis and gonadal sex differentiation in tadpoles of the African clawed frog, Xenopus laevis

USGS Publications Warehouse

Sharma, Bibek; Patino, R.

2009-01-01

Xenopus laevis larvae were exposed to cadmium (Cd) at 0, 1, 8, 85 or 860 ??g L-1 in FETAX medium from 0 to 86 d postfertilization. Premetamorphic tadpoles were sampled on day 31; pre and prometamorphic tadpoles on day 49; and frogs (NF stage 66) between days 50 and 86. Survival, snout-vent length (SVL), tail length, total length, hindlimb length (HLL), initiation of metamorphic climax, size at and completion of metamorphosis, and gonadal condition and sex ratio (assessed histologically) were determined. Survival was unaffected by Cd until day 49, but increased mortality was observed after day 49 at 860 ??g Cd L-1. On day 31, when tadpoles were in early premetamorphosis, inhibitory effects on tadpole growth were observed only at 860 ??g Cd L-1. On day 49, when most tadpoles where in late premetamorphosis/early prometamorphosis, reductions in SVL, HLL and total length were observed at 8 and 860 but not 85 ??g L-1, thus creating a U-shaped size distribution at 0-85 ??g Cd L-1. However, this U-shaped size pattern was not evident in postmetamorphic individuals. In fact, frog size at completion of metamorphosis was slightly smaller at 85 ??g Cd L-1relative to control animals. These observations confirmed a recent report of a Cd concentration-dependent bimodal growth pattern in late-premetamorphic Xenopus tadpoles, but also showed that growth responses to varying Cd concentrations change with development. The fraction of animals initiating or completing metamorphosis during days 50-86 was reduced in a Cd concentration-dependent manner. Testicular histology and population sex ratios were unaffected by Cd suggesting that, unlike mammals, Cd is not strongly estrogenic in Xenopus tadpoles. ?? 2009 Elsevier Ltd.

Effects of cadmium on growth, metamorphosis and gonadal sex differentiation in tadpoles of the African clawed frog, Xenopus laevis

USGS Publications Warehouse

Sharma, Bibek; Patino, Reynaldo

2009-01-01

Xenopus laevis larvae were exposed to cadmium (Cd) at 0, 1, 8. 85 or 860 mu g L(-1) in FETAX medium from 0 to 86 d postfertilization. Premetamorphic tadpoles were sampled on day 3 1; pre and prometamorphic tadpoles on day 49; and frogs (NF stage 66) between days 50 and 86. Survival, snout-vent length (SVL), tail length, total length, hindlimb length (HLL), initiation of metamorphic climax, size at and completion of metamorphosis, and gonadal condition and sex ratio (assessed histologically) were determined. Survival was unaffected by Cd until day 49, but increased mortality was observed after day 49 at 860 mu g Cd L(-1). On day 31, when tadpoles were in early premetamorphosis, inhibitory effects on tadpole growth were observed only at 860 mu g Cd L(-1). On day 49, when most tadpoles where in late premetamorphosis/early prometamorphosis, reductions in SVL, HLL and total length were observed at 8 and 860 but not 85 mu g L(-1), thus creating a U-shaped size distribution at 0-85 mu g Cd L(-1). However, this U-shaped size pattern was not evident in postmetamorphic individuals. In fact, frog size at completion of metamorphosis was slightly smaller at 85 mu g Cd L(-1) relative to control animals. These observations confirmed a recent report of a Cd concentration-dependent bimodal growth pattern in late-premetamorphic Xenopus tadpoles, but also showed that growth responses to varying Cd concentrations change with development. The fraction of animals initiating or completing metamorphosis during days 50-86 was reduced in a Cd concentration-dependent manner. Testicular histology and population sex ratios were unaffected by Cd suggesting that, unlike mammals, Cd is not strongly estrogenic in Xenopus tadpoles.

TADPOLE GALAXIES IN THE HUBBLE ULTRA DEEP FIELD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elmegreen, Bruce G.; Elmegreen, Debra Meloy, E-mail: bge@watson.ibm.co, E-mail: elmegreen@vassar.ed

2010-10-20

Tadpole galaxies have a head-tail shape with a large clump of star formation at the head and a diffuse tail or streak of stars off to one side. We measured the head and tail masses, ages, surface brightnesses, and sizes for 66 tadpoles in the Hubble Ultra Deep Field (UDF) and looked at the distribution of neighbor densities and tadpole orientations with respect to neighbors. The heads have masses of 10{sup 7}-10{sup 8} M{sub sun} and photometric ages of {approx}0.1 Gyr for z {approx} 2. The tails have slightly larger masses than the heads and comparable or slightly older ages.more » The most obvious interpretation of tadpoles as young merger remnants is difficult to verify. They have no enhanced proximity to other resolved galaxies as a class, and the heads, typically <0.2 kpc in diameter, usually have no obvious double-core structure. Another possibility is ram pressure interaction between a gas-rich galaxy and a diffuse cosmological flow. Ram pressure can trigger star formation on one side of a galaxy disk, giving the tadpole shape when viewed edge-on. Ram pressure can also strip away gas from a galaxy and put it into a tail, which then forms new stars and gravitationally drags along old stars with it. Such an effect might have already been observed in the Virgo Cluster. Another possibility is that tadpoles are edge-on disks with large, off-center clumps. Analogous lop-sided star formation in UDF clump clusters is shown.« less

Metabolism of thyroxine in Rana catesbeiana tadpoles during metamorphic climax

DOE Office of Scientific and Technical Information (OSTI.GOV)

Galton, V.A.; Munck, K.

1981-01-01

Previous studies have indicated that premetamorphic tadpoles do not convert T4 to T3 to a measurable extent (1). The present study was performed to determine whether a T4 5'-monodeiodinating system is acquired at later stages of development. (/sup 125/I)T4 metabolism in vivo was determined in tadpoles at most stages of prometamorphosis and metamorphic climax and, for comparison, in premetamorphic tadpoles. The conversion of (/sup 125/I)T4 to (/sup 125/I)T3, as indicated by the presence of an /sup 125/I-labeled product in serum and liver preparations that cochromatographed with carrier T3, was sometimes observed in tadpoles near the end of prometamorphosis and wasmore » always evident in tadpoles that were either undergoing or had completed metamorphic climax. However, during this phase, no correlation could be drawn between the extent of T3 production and morphological development. The formation of T3 from T4 in vivo was significantly decreased in tadpoles pretreated with propylthiouracil. The T45'-monodeiodinating system could be induced in premetamorphic tadpoles by injecting them with either T4 or T3. This finding together with the observation that normal acquisition of this system occurs at the time when endogenous T4 and T3 levels are rising rapidly suggest that its development is under the control of the thyroid hormones.« less

Embryonic background risk promotes the survival of tadpoles facing surface predators

PubMed Central

Chivers, Douglas P.; Ferrari, Maud C. O.

2018-01-01

Exposure to intense predation risk can induce morphological and behavioural phenotypes that prepare prey, often at young ages, for surviving attacks from unknown predators. However, previous studies revealed that this survival advantage depended on the predator species. Here, we used alarm cues from injured conspecifics to simulate a period of high predation risk for embryonic wood frogs, Lithobates sylvaticus. Two weeks post-hatching, we tested whether the embryonic risk exposure influenced survival in encounters with two novel predators: (1) a spider (Dolomedes sp.) that ambushes prey exclusively on the surface of the water, and (2) the adult predacious diving beetle (Dytiscus sp.) which displays underwater sit-and-wait posture and pursuit tactics. Tadpoles exposed to embryonic high-risk survived longer when encountering spiders, whereas background risk had no influence on survival with adult beetles. These findings, coupled with survival studies involving other predator types, indicate that a high-risk environment promotes tadpole survival in future encounters with unknown sit-and-wait predators, but at the cost of increased vulnerability to novel predators capable of active pursuit. PMID:29561913

Thermal Acclimatization in Overwintering Tadpoles of the Green Frog, Lithobates clamitans (Latreille, 1801).

PubMed

Gray, Kathryn T; Escobar, Astrid M; Schaeffer, Paul J; Mineo, Patrick M; Berner, Nancy J

2016-06-01

Seasonal acclimatization permits organisms to maintain function in the face of environmental change. Tadpoles of the green frog (Lithobates clamitans) overwinter as tadpoles in much of their range. Because they are active in winter, we hypothesized that green frog tadpoles would display acclimatization of metabolic and locomotor function. We collected tadpoles in Sewanee, Tennessee (35.2°N) in winter and summer. Tadpoles collected during each season were tested at both winter (8°C) and summer (26°C) temperatures. Winter tadpoles were able to maintain swimming performance at both temperatures, whereas swimming performance decreased at cold temperatures in summer tadpoles. There was no evidence for seasonal acclimatization of whole-animal metabolic rate. Although whole-animal metabolic acclimatization was not observed, the activities of cytochrome c oxidase, citrate synthase, and lactate dehydrogenase measured in skeletal muscle homogenates showed higher activity in winter-acclimatized tadpoles indicating compensation for temperature. Further, the composition of muscle membranes of winter tadpoles had less saturated and more monounsaturated fatty acids and a higher ω-3 balance, unsaturation index, and peroxidation index than summer tadpoles. These data indicate that reversible phenotypic plasticity of thermal physiology occurs in larval green frog tadpoles. They appear to compensate for colder temperatures to maintain burst-swimming velocity and the ability to escape predators without the cost of maintaining a constant, higher standard metabolic rate in the winter. © 2016 Wiley Periodicals, Inc.

Tadpole-improved SU(2) lattice gauge theory

NASA Astrophysics Data System (ADS)

Shakespeare, Norman H.; Trottier, Howard D.

1999-01-01

A comprehensive analysis of tadpole-improved SU(2) lattice gauge theory is made. Simulations are done on isotropic and anisotropic lattices, with and without improvement. Two tadpole renormalization schemes are employed, one using average plaquettes, the other using mean links in the Landau gauge. Simulations are done with spatial lattice spacings as in the range of about 0.1-0.4 fm. Results are presented for the static quark potential, the renormalized lattice anisotropy at/as (where at is the ``temporal'' lattice spacing), and for the scalar and tensor glueball masses. Tadpole improvement significantly reduces discretization errors in the static quark potential and in the scalar glueball mass, and results in very little renormalization of the bare anisotropy that is input to the action. We also find that tadpole improvement using mean links in the Landau gauge results in smaller discretization errors in the scalar glueball mass (as well as in the static quark potential), compared to when average plaquettes are used. The possibility is also raised that further improvement in the scalar glueball mass may result when the coefficients of the operators which correct for discretization errors in the action are computed beyond the tree level.

Muscle Responses to Stimulation of the Tadpole Tail

ERIC Educational Resources Information Center

Funkhouser, Anne

1976-01-01

Describes use of tail muscles and spinal cord in the tadpole as an alternative source for muscle-and-nerve experiments. Includes explanation of simple dissection and preparation of tadpole; instructions for experiments such as threshold, strength of stimulus, frequency of stimulus, single twitch, tetanus, fatigue, effects of temperature on…

Atmospheric pressure plasma accelerates tail regeneration in tadpoles Xenopus laevis

NASA Astrophysics Data System (ADS)

Rivie, A.; Martus, K.; Menon, J.

2017-08-01

Atmospheric pressure plasma is a partially ionized gas composed of neutral and charged particles, including electrons and ions, as well as reactive oxygen species (ROS). Recently, it is utilized as possible therapy in oncology, sterilization, skin diseases, wound healing and tissue regeneration. In this study we focused on effect of plasma exposure on tail regeneration of tadpoles, Xenopus leavis with special emphasis on role of ROS, antioxidant defenses and morphological features of the regenerate. When amputated region of the tail was exposed to the helium plasma it resulted in a faster rate of growth, elevated ROS and increase in antioxidant enzymes in the regenerate compared to that of untreated control. An increase in nitric oxide (free radical) as well as activity of nitric oxide synthase(s) were observed once the cells of the regeneration blastema - a mass of proliferating cells are ready for differentiation. Microscopically the cells of the regenerate of plasma treated tadpoles show altered morphology and characteristics of cellular hypoxia and oxidative stress. We summarize that plasma exposure accelerates the dynamics of wound healing and tail regeneration through its effects on cell proliferation and differentiation as well as angiogenesis mediated through ROS signaling.

Anuran radiations and the evolution of tadpole morphospace

PubMed Central

Roelants, Kim; Haas, Alexander; Bossuyt, Franky

2011-01-01

Anurans (frogs and toads) are unique among land vertebrates in possessing a free-living larval stage that, parallel to adult frogs, diversified into an impressive range of ecomorphs. The tempo and mode at which tadpole morphology evolved through anuran history as well as its relationship to lineage diversification remain elusive. We used a molecular phylogenetic framework to examine patterns of morphological evolution in tadpoles in light of observed episodes of accelerated lineage diversification. Our reconstructions show that the expansion of tadpole morphospace during the basal anuran radiation in the Triassic/Early Jurassic was unparalleled by the basal neobatrachian radiation in the Late Jurassic/Early Cretaceous or any subsequent radiation in the Late Cretaceous/Early Tertiary. Comparative analyses of radiation episodes indicate that the slowdown of morphospace expansion was caused not only by a drop in evolutionary rate after the basal anuran radiation but also by an overall increase in homoplasy in the characters that did evolve during later radiations. The overlapping sets of evolving characters among more recent radiations may have enhanced tadpole diversity by creating unique combinations of homoplastic traits, but the lack of innovative character changes prevented the exploration of fundamental regions in morphospace. These complex patterns transcend the four traditionally recognized tadpole morphotypes and apply to most tissue types and body parts. PMID:21555583

Heavy metal speciation and uptake in crayfish and tadpoles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bundy, K.J.; Berzins, D.; Millet, L.

1996-12-31

Developing valid pollution recording methods is central to assessing environmental damage and remediation. This often is difficult, however, because of speciation and multiphase distribution of contaminants. Polarography, an electroanalytical technique capable of detection and quantification of trace levels of elements and ionic complexes, is a promising method for analyzing environmental samples. Here, polarography has been used to determine lead concentration in water, sediment, bullfrogs, tadpoles, and adsorbed onto kaolin. It has also been used to measure hexavalent chromium concentration in crayfish. This research involves field studies and two laboratory experiments. Studies of a Louisiana swamp have shown lead`s affinity formore » sediment and water particulate phases, rather than being ionically dissolved in the aqueous phase. In swamp bullfrogs, lead was found in greater concentrations in bone compared to muscle. In the first laboratory experiment, lead uptake originating from water and sediment increased in tadpoles as exposure time and concentration increased. Also, this animal`s development was hindered at higher concentrations. The second laboratory experiment exposed crayfish to aqueous hexavalent chromium. Total chromium uptake increased with exposure time and concentration. The chromium tissue abundance was hepatopancreas > gills > muscle. A substantial portion of tissue hexavalent chromium converted to the less toxic trivalent form.« less

Chronic effects of environmentally-relevant concentrations of lead in Pelophylax nigromaculata tadpoles: Threshold dose and adverse effects.

PubMed

Huang, Min-Yi; Duan, Ren-Yan; Ji, Xiang

2014-06-01

Lead (Pb) is a common heavy metal in the natural environment, but its concentration has been increasing alongside widespread industrial and agricultural development in China. The dark-spotted frog Pelophylax (formerly Rana) nigromaculata (Anura: Ranidae) is distributed across East Asia and inhabits anthropogenic habitats such as farmland. Here, P. nigromaculata tadpoles (Gosner stage 19-46) were exposed to Pb at different concentrations (0, 40, 80, 160, 320, 640 and 1280µg/L) and Pb-induced survival, metamorphosis time, development, malformations, mobility and gonad structure were monitored. The results showed that above the threshold concentration of Pb, adverse effects were obvious. As the concentration of Pb increased, the adverse effects on different traits followed different patterns: the effects on hindlimb length, survival rate, metamorphosis rate, total malformation rate, swimming speed and jumping speed largely exhibited a linear pattern; the effects on snout-vent length, body mass and forelimb length largely exhibited a bimodal pattern. Sex ratio and gonadal histology were not affected by Pb, suggesting that Pb is not strongly estrogenic in P. nigromaculata. Copyright © 2014 Elsevier Inc. All rights reserved.

Hot tadpoles from cold environments need more nutrients--life history and stoichiometry reflects latitudinal adaptation.

PubMed

Liess, Antonia; Rowe, Owen; Guo, Junwen; Thomsson, Gustaf; Lind, Martin I

2013-11-01

1. High-latitude species (and populations within species) are adapted to short and cold summers. They often have high growth and development rates to fully use the short growing season and mature before the onset of winter. 2. Within the context of ecological stoichiometry theory, this study combines ecology with evolution by relating latitudinal life-history adaptations to their molecular consequences in body nutrient composition in Rana temporaria tadpoles. 3. Temperature and food quality were manipulated during the development of tadpoles from Arctic and Boreal origins. We determined tadpole growth rate, development rate, body size and nutrient content, to test whether (i) Arctic tadpoles could realize higher growth rates and development rates with the help of higher-quality food even when food quantity was unchanged, (ii) Arctic and Boreal tadpoles differed in their stoichiometric (and life history) response to temperature changes, (iii) higher growth rates lead to higher tadpole P content (growth rate hypothesis) and (iv) allometric scaling affects tadpole nutrient allocation. 4. We found that especially Arctic tadpoles grew and developed faster with the help of higher-quality food and that tadpoles differed in their stoichiometric (and life history) response to temperature changes depending on region of origin (probably due to different temperature optima). There was no evidence that higher growth rates mediated the positive effect of temperature on tadpole P content. On the contrary, the covariate growth rate was negatively connected with tadpole P content (refuting the growth rate hypothesis). Lastly, tadpole P content was not related to body size, but tadpole C content was higher in larger tadpoles, probably due to increased fat storage. 5. We conclude that temperature had a strong effect on tadpole life history, nutrient demand and stoichiometry and that this effect depended on the evolved life history. © 2013 The Authors. Journal of Animal Ecology �

Mean link versus average plaquette tadpoles in lattice NRQCD

NASA Astrophysics Data System (ADS)

Shakespeare, Norman H.; Trottier, Howard D.

1999-03-01

We compare mean-link and average plaquette tadpole renormalization schemes in the context of the quarkonium hyperfine splittings in lattice NRQCD. Simulations are done for the three quarkonium systems c overlinec, b overlinec, and b overlineb. The hyperfine splittings are computed both at leading and at next-to-leading order in the relativistic expansion. Results are obtained at a large number of lattice spacings. A number of features emerge, all of which favor tadpole renormalization using mean links. This includes much better scaling of the hyperfine splittings in the three quarkonium systems. We also find that relativistic corrections to the spin splittings are smaller with mean-link tadpoles, particularly for the c overlinec and b overlinec systems. We also see signs of a breakdown in the NRQCD expansion when the bare quark mass falls below about one in lattice units (with the bare quark masses turning out to be much larger with mean-link tadpoles).

Tadpoles balance foraging and predator avoidance: Effects of predation, pond drying, and hunger

USGS Publications Warehouse

Bridges, C.M.

2002-01-01

Organisms are predicted to make trade-offs when foraging and predator avoidance behaviors present conflicting demands. Balancing conflicting demands is important to larval amphibians because adult fitness can be strongly influenced by size at metamorphosis and duration of the larval period. Larvae in temporary ponds must maximize growth within a short time period to achieve metamorphosis before ponds dry, while simultaneously avoiding predators. To determine whether tadpoles trade off between conflicting demands, I examined tadpole (Pseudacris triseriata) activity and microhabitat use in the presence of red-spotted newts (Notopthalmus viridescens) under varying conditions of pond drying and hunger. Tadpoles significantly decreased activity and increased refuge use when predators were present. The proportion of active time tadpoles spent feeding was significantly greater in predator treatments, suggesting tadpoles adaptively balance the conflicting demands of foraging and predator avoidance without making apparent trade-offs. Tadpoles responded to simulated drying conditions by accelerating development. Pond drying did not modify microhabitat use or activity in the presence of predators, suggesting tadpoles perceived predation and hunger as greater immediate threats than desiccation, and did not take more risks.

The Intestinal Microbiota of Tadpoles Differs from Those of Syntopic Aquatic Invertebrates.

PubMed

Lyra, Mariana L; Bletz, Molly C; Haddad, Célio F B; Vences, Miguel

2017-11-20

Bacterial communities associated to eukaryotes play important roles in the physiology, development, and health of their hosts. Here, we examine the intestinal microbiota in tadpoles and aquatic invertebrates (insects and gastropods) to better understand the degree of specialization in the tadpole microbiotas. Samples were collected at the same time in one pond, and the V4 region of the bacterial 16S rRNA gene was sequenced with Illumina amplicon sequencing. We found that bacterial richness and diversity were highest in two studied snail individuals, intermediate in tadpoles, and lowest in the four groups of aquatic insects. All groups had substantial numbers of exclusive bacterial operational taxonomic units (OTUs) in their guts, but also shared a high proportion of OTUs, probably corresponding to transient environmental bacteria. Significant differences were found for all pairwise comparisons of tadpoles and snails with the major groups of insects, but not among insect groups or between snails and tadpoles. The similarity between tadpoles and snails may be related to similar feeding mode as both snails and tadpoles scratch biofilms and algae from surfaces; however, this requires confirmation due to low sample sizes. Overall, the gut microbiota differences found among syntopic aquatic animals are likely shaped by both food preferences and host identity.

Vortex Formation and Foraging in Polyphenic Spadefoot Toad Tadpoles.

PubMed

Bazazi, Sepideh; Pfennig, Karin S; Handegard, Nils Olav; Couzin, Iain D

2012-06-01

Animal aggregations are widespread in nature and can exhibit complex emergent properties not found at an individual level. We investigate one such example here, collective vortex formation by congeneric spadefoot toad tadpoles: Spea bombifrons and S. multiplicata. Tadpoles of these species develop into either an omnivorous or a carnivorous (cannibalistic) morph depending on diet. Previous studies show S. multiplicata are more likely to develop into omnivores and feed on suspended organic matter in the water body. The omnivorous morph is frequently social, forming aggregates that move and forage together, and form vortices in which they adopt a distinctive slowly-rotating circular formation. This behaviour has been speculated to act as a means to agitate the substratum in ponds and thus could be a collective foraging strategy. Here we perform a quantitative investigation of the behaviour of tadpoles within aggregates. We found that only S. multiplicata groups exhibited vortex formation, suggesting that social interactions differ between species. The probability of collectively forming a vortex, in response to introduced food particles, increased for higher tadpole densities and when tadpoles were hungry. Individuals inside a vortex moved faster and exhibited higher (by approximately 27%) tailbeat frequencies than those outside the vortex, thus incurring a personal energetic cost. The resulting environmental modification, however, suggests vortex behaviour may be an adaptation to actively create, and exploit, a resource patch within the environment.

Spatial and Temporal Variation in Tadpole Communities in Neotropical Montane Streams.

NASA Astrophysics Data System (ADS)

Brenes, R.; Lips, K. R.

2005-05-01

Tadpoles transfer nutrients and energy between environments and amphibian declines are likely to affect this process. As the first step in determining amphibian production, we quantified seasonal and microhabitat variation in abundance and diversity of tadpoles at two sites: pre and post-decline. We quantified density of all tadpole species in riffles, runs, and pools monthly for a year. Three species occurred at the decline site (average density = 0.0026 ± 0.0034 m-2), and 10 of 11 species occurred year-round at the healthy site (2.80 ± 4.37 m-2). Tadpole abundance varied seasonally, with more tadpoles (X2=270.23, 10 d.f., p<0.001) at lower densities (0.50 m-2 ± 0.58) during the rainy season than during the dry season (5.10 m-2 ± 5.31; t = 3.079, 10 d.f., P= 0.01). Microhabitats differed in overall density (leaf packs, 1.044 ± 1.17 m-2; riffles, 0.04 ± 0.013 m-2, pools 0.38 ± 0.005 m-2; isolated pools 2.09 ± 1.03 m-2). Riffles and pools had a diverse tadpole assemblage, but leaf packs and isolated pools were dominated by Hyalinobatrachium colymbiphyllum (3.74 ± 1.86 m-2, F= 13.47, p=0.01) and Colostethus flotator (9.35 ± 4.56 m-2, F=32.77, p=0.002), respectively. High abundance, density, prevalence, and persistence suggest an important role for tadpoles in these ecosystems.

Effects of behavioral and morphological plasticity on risk of predation in a Neotropical tadpole

USGS Publications Warehouse

McIntyre, P.B.; Baldwin, S.; Flecker, A.S.

2004-01-01

Predator-induced phenotypic plasticity is widespread among aquatic animals, however the relative contributions of behavioral and morphological shifts to reducing risk of predation remain uncertain. We tested the phenotypic plasticity of a Neotropical tadpole (Rana palmipes) in response to chemical cues from predatory Belostoma water bugs, and how phenotype affects risk of predation. Behavior, morphology, and pigmentation all were plastic, resulting in a predator-induced phenotype with lower activity, deeper tail fin and muscle, and darker pigmentation. Tadpoles in the predator cue treatment also grew more rapidly, possibly as a result of the nutrient subsidy from feeding the caged predator. For comparison to phenotypes induced in the experiment, we quantified the phenotype of tadpoles from a natural pool. Wildcaught tadpoles did not match either experimentally induced phenotype; their morphology was more similar to that produced in the control treatment, but their low swimming activity was similar to that induced by predator cues. Exposure of tadpoles from both experimental treatments and the natural pool to a free-ranging predator confirmed that predator-induced phenotypic plasticity reduces risk of predation. Risk of predation was comparable among wild-caught and predator-induced tadpoles, indicating that behavioral shifts can substantially alleviate risk in tadpoles that lack the typical suite of predator-induced morphological traits. The morphology observed in wild-caught tadpoles is associated with rapid growth and high competition in other tadpole species, suggesting that tadpoles may profitably combine a morphology suited to competition for food with behaviors that minimize risk of predation. ?? Springer-Verlag 2004.

Toxicity of Bacillus thuringiensis var. israelensis in aqueous suspension on the South American common frog Leptodactylus latrans (Anura: Leptodactylidae) tadpoles.

PubMed

Lajmanovich, Rafael C; Junges, Celina M; Cabagna-Zenklusen, Mariana C; Attademo, Andrés M; Peltzer, Paola M; Maglianese, Mariana; Márquez, Vanina E; Beccaria, Alejandro J

2015-01-01

The effects of commercial formulations of Bacillus thuringiensisvar.israelensis (Bti) on non-target organisms are still a matter of debate; in amphibians, the risks of Bti are little known. To evaluate the toxicity of a commercial liquid (aqueous suspension, AS) formulation of Bti (Introban(®)) on Leptodactylus latrans tadpoles, including median lethal concentration (LC50) and no-and lowest-observed-effect concentrations (NOEC and LOEC, respectively), as well as the possible effects of Bti on oxidative responses, erythrocytes genotoxicity, and histology of the intestines. In the laboratory, tadpoles were exposed to nominal concentrations of 0 (control), 2.5, 5, 10, 20 and 40 mg/L of formulated Bti-AS. Glutathione S-transferase (GST) and catalase (CAT) activities, as well as formation of erythrocyte nuclear abnormalities (ENAs), and histological effect were measured in tadpoles displaying survival rates >85%. L. latrans tadpoles were sensitive to exposure to Bti-AS, reaching 100% mortality after 48 h of exposure at the highest concentration. Bti-AS induced GST and CAT enzymes and genotoxicity (erythrocyte's nuclear abnormalities), and caused intestine's histopathology. Our results demonstrate that toxicity of Bti-AS is dose-dependent for L. latrans tadpoles and that sublethal exposure alters enzymes of oxidative stress, induces genotoxicity, and causes intestine damage. Further research is needed to evaluate the ecotoxicological risk of the massive use of Bti formulations on amphibian populations that commonly used suburban wastewater or urban waterbodies to reproduce and where this biopesticide is frequently applied. Copyright © 2014 Elsevier Inc. All rights reserved.

Chronic toxicity of copper on embryo development in Chinese toad, Bufo gargarizans.

PubMed

Xia, Kun; Zhao, Hongfeng; Wu, Minyao; Wang, Hongyuan

2012-06-01

This study examined the effects of copper exposure on embryonic development of Chinese toad, Bufo gargarizans. Firstly, the LC(50) values from 24 to 96 h of exposure were 3.61×10(-6) M, by means of a 4 d toxicity test with B. gargarizans embryos. Secondly, Chinese toad embryos were exposed to 10(-9)-10(-6) M copper from mid gastrula stage to operculum completion stage. Measurements included mortality, tadpole weight, tadpole total length, growth retardation, duration of different embryo stages and malformation. Embryonic survival was not affected by copper. Relative to control tadpoles, significantly decreased weight and total length were found at 10(-9)-10(-6) M reduced percentage of the embryos in right operculum stage after 10 d exposure to copper and reduced percentage of embryos in operculum completion stage after 12 d exposure to copper were also observed. Moreover, the duration of embryonic development increased at neural, circulation and operculum development stage in copper-treated groups. For the scanning microscope and histological observation, the abnormalities were malformation of wavy dorsal fin, flexural tail, curvature body axis, yolk sac oedema and reduced pigmentation in the yolk sac. Histopathological changes in olfactory, retinal epithelium and skin were also observed. DNA strand breaks exposed to the copper were analyzed by DNA ladder. In conclusion, copper induced toxic effects on B. gargarizans embryos. The present study indicated chronic toxicity tests may provide more accurate way in formulating the "safe levels" of heavy metals to amphibian. Copyright © 2012 Elsevier Ltd. All rights reserved.

Environmentally-relevant concentrations of atrazine induce non-monotonic acceleration of developmental rate and increased size at metamorphosis in Rhinella arenarum tadpoles.

PubMed

Brodeur, Julie C; Sassone, Alina; Hermida, Gladys N; Codugnello, Nadia

2013-06-01

Despite of the various studies reporting on the subject, anticipating the impacts of the widely-used herbicide atrazine on anuran tadpoles metamorphosis remains complex as increases or decreases of larval period duration are almost as frequently reported as an absence of effect. The aim of the present study was to examine the effects of environmentally-relevant concentrations of atrazine (0.1, 1, 10, 100, and 1000μg/L) on the timings of metamorphosis and body size at metamorphosis in the common South American toad, Rhinella arenarum (Anura: bufonidae). None of the atrazine concentrations tested significantly altered survival. Low atrazine concentrations in the range of 1-100μg/L were found to accelerate developmental rate in a non-monotonic U-shaped concentration-response relationship. This observed acceleration of the metamorphic process occurred entirely between stages 25 and 39; treated tadpoles proceeding through metamorphosis as control animals beyond this point. Together with proceeding through metamorphosis at a faster rate, tadpoles exposed to atrazine concentrations in the range of 1-100μg/L furthermore transformed into significantly larger metamorphs than controls, the concentration-response curve taking the form of an inverted U in this case. The no observed effect concentration (NOEC) was 0.1μg atrazine/L for both size at metamorphosis and timings of metamorphosis. Tadpoles exposed to 100μg/L 17β-estradiol presented the exact same alterations of developmental rate and body size as those treated with 1, 10 and 100μg/L of atrazine. Elements of the experimental design that facilitated the detection of alterations of metamorphosis at low concentrations of atrazine are discussed, together with the ecological significance of those findings. Copyright © 2013 Elsevier Inc. All rights reserved.

Gut bacterial communities across tadpole ecomorphs in two diverse tropical anuran faunas

NASA Astrophysics Data System (ADS)

Vences, Miguel; Lyra, Mariana L.; Kueneman, Jordan G.; Bletz, Molly C.; Archer, Holly M.; Canitz, Julia; Handreck, Svenja; Randrianiaina, Roger-Daniel; Struck, Ulrich; Bhuju, Sabin; Jarek, Michael; Geffers, Robert; McKenzie, Valerie J.; Tebbe, Christoph C.; Haddad, Célio F. B.; Glos, Julian

2016-04-01

Animal-associated microbial communities can play major roles in the physiology, development, ecology, and evolution of their hosts, but the study of their diversity has yet focused on a limited number of host species. In this study, we used high-throughput sequencing of partial sequences of the bacterial 16S rRNA gene to assess the diversity of the gut-inhabiting bacterial communities of 212 specimens of tropical anuran amphibians from Brazil and Madagascar. The core gut-associated bacterial communities among tadpoles from two different continents strongly overlapped, with eight highly represented operational taxonomic units (OTUs) in common. In contrast, the core communities of adults and tadpoles from Brazil were less similar with only one shared OTU. This suggests a community turnover at metamorphosis. Bacterial diversity was higher in tadpoles compared to adults. Distinct differences in composition and diversity occurred among gut bacterial communities of conspecific tadpoles from different water bodies and after experimental fasting for 8 days, demonstrating the influence of both environmental factors and food on the community structure. Communities from syntopic tadpoles clustered by host species both in Madagascar and Brazil, and the Malagasy tadpoles also had species-specific isotope signatures. We recommend future studies to analyze the turnover of anuran gut bacterial communities at metamorphosis, compare the tadpole core communities with those of other aquatic organisms, and assess the possible function of the gut microbiota as a reservoir for protective bacteria on the amphibian skin.

Predator-prey interactions between Synbranchus marmoratus (Teleostei: Synbranchidae) and Hypsiboas pulchellus tadpoles (Amphibia: Hylidae): importance of lateral line in nocturnal predation and effects of fenitrothion exposure.

PubMed

Junges, Celina M; Lajmanovich, Rafael C; Peltzer, Paola M; Attademo, Andres M; Bassó, Agustín

2010-11-01

Environmental contaminants can disrupt interactions between aquatic species by altering community structure. We explored predator-prey interactions between marbled swamp juvenile eels (Synbranchus marmoratus; predator) and anuran tadpoles (Hypsiboas pulchellus; prey) in relation to two aspects: the importance of lateral line in the predator and whether the absence of light modifies predation rates; and the effect of a sub-lethal concentration of fenitrothion on both predator and prey. Eels were tested under two sensory conditions (lateral line intact and lateral line blocked by cobalt chloride) in dark conditions. Predation rates were evaluated using different treatments that combined predator and prey exposed or not to insecticide. Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities were also measured in muscle samples of eels and tadpoles to explore whether fenitrothion affects predator and prey differentially. Marbled swamp eels were more efficient in feeding on tadpoles during the night than during the day, showing that lateral line makes an important contribution to prey detection and capture. Regarding pesticide effects, short-term (6 h) exposure to an ecologically relevant fenitrothion dose of 2.5 mg L(-1) altered the predator-prey relationship by changing prey behaviour, reducing prey detection and therefore increasing tadpole survival. At this concentration, the outcome of the predator-prey relationship appears biased in favor of the exposed tadpoles, which were released from predation risk, despite their altered behaviour and the higher inhibition percentages of tail BChE (70%) and AChE (51%) than in control individuals. Our study involving these model species and agrochemicals demonstrates that fenitrothion affected the outcome of a predator-prey relationship. Further studies are needed, in these species and other native amphibians, to investigate the nature of the mechanisms responsible for the adverse effects of pesticides on

Growth and development of larval green frogs (Rana clamitans) exposed to multiple doses of an insecticide

USGS Publications Warehouse

Boone, M.D.; Bridges, C.M.; Rothermel, B.B.

2001-01-01

Our objective was to determine how green frogs (Rana clamitans) are affected by multiple exposures to a sublethal level of the carbamate insecticide, carbaryl, in outdoor ponds. Tadpoles were added to 1,000-1 ponds at a low or high density which were exposed to carbaryl 0, 1, 2, or 3 times. Length of the larval period, mass, developmental stage, tadpole survival, and proportion metamorphosed were used to determine treatment effects. The frequency of dosing affected the proportion of green frogs that reached metamorphosis and the developmental stage of tadpoles. Generally, exposure to carbaryl increased rates of metamorphosis and development. The effect of the frequency of carbaryl exposure on development varied with the density treatment; the majority of metamorphs and the most developed tadpoles came from high-density ponds exposed to carbaryl 3 times. This interaction suggests that exposure to carbaryl later in the larval period stimulated metamorphosis, directly or indirectly, under high-density conditions. Our study indicates that exposure to a contaminant can lead to early initiation of metamorphosis and that natural biotic factors can mediate the effects of a contaminant in the environment.

Adjoint affine fusion and tadpoles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Urichuk, Andrew, E-mail: andrew.urichuk@uleth.ca; Walton, Mark A., E-mail: walton@uleth.ca; International School for Advanced Studies

2016-06-15

We study affine fusion with the adjoint representation. For simple Lie algebras, elementary and universal formulas determine the decomposition of a tensor product of an integrable highest-weight representation with the adjoint representation. Using the (refined) affine depth rule, we prove that equally striking results apply to adjoint affine fusion. For diagonal fusion, a coefficient equals the number of nonzero Dynkin labels of the relevant affine highest weight, minus 1. A nice lattice-polytope interpretation follows and allows the straightforward calculation of the genus-1 1-point adjoint Verlinde dimension, the adjoint affine fusion tadpole. Explicit formulas, (piecewise) polynomial in the level, are writtenmore » for the adjoint tadpoles of all classical Lie algebras. We show that off-diagonal adjoint affine fusion is obtained from the corresponding tensor product by simply dropping non-dominant representations.« less

Lead concentrations in bullfrog Rana catesbeiana and green frog R. clamitans tadpoles inhabiting highway drainages

USGS Publications Warehouse

Birdsall, C.W.; Grue, C.E.; Anderson, A.

1986-01-01

Lead concentrations were determined in sediment and tadpoles of bullfrogs Rana catesbeiana and green frogs R. clamitans from drainages along highways with different daily average traffic volumes (range, 4272 to I08,800 vehicles day-I) and from ponds >0.4 km from the nearest highway. Lead concentrations (mg kg--I dry weight) in sediment (7-8 to 940) were usually greater (4-5 times) than those in the tadpoles (bullfrog, 0,07 to 270; green frog, 0,90 to 240 mg kg-I). Lead concentrations in sediment (r =0.63) and in both species of tadpoles (bullfrog, r = 0.69; green frog, r = 0.57) were positively correlated with average daily traffic volume. Lead concentrations in both species of tadpoles (bullfrog, r = (). 76: green frog, r = 0.75) were also positively correlated with lead concentrations in sediment. At sites where both bullfrog and green frog tadpoles were collected. lead concentrations in the two species were closely related (r = 0.84). Lead concentrations in tadpoles living near highways may contribute to the elevated lead levels reported in wildlife that are potential tadpole predators. Dietary lead concentrations similar to those in our tadpoles have been associated with physiological and reproductive effects in some species of birds and mammals. However, additional data are needed to determine the hazards to predators of lead concentrations in tadpoles.

Skeletal muscle regeneration in Xenopus tadpoles and zebrafish larvae

PubMed Central

2012-01-01

Background Mammals are not able to restore lost appendages, while many amphibians are. One important question about epimorphic regeneration is related to the origin of the new tissues and whether they come from mature cells via dedifferentiation and/or from stem cells. Several studies in urodele amphibians (salamanders) indicate that, after limb or tail amputation, the multinucleated muscle fibres do dedifferentiate by fragmentation and proliferation, thereby contributing to the regenerate. In Xenopus laevis tadpoles, however, it was shown that muscle fibres do not contribute directly to the tail regenerate. We set out to study whether dedifferentiation was present during muscle regeneration of the tadpole limb and zebrafish larval tail, mainly by cell tracing and histological observations. Results Cell tracing and histological observations indicate that zebrafish tail muscle do not dedifferentiate during regeneration. Technical limitations did not allow us to trace tadpole limb cells, nevertheless we observed no signs of dedifferentiation histologically. However, ultrastructural and gene expression analysis of regenerating muscle in tadpole tail revealed an unexpected dedifferentiation phenotype. Further histological studies showed that dedifferentiating tail fibres did not enter the cell cycle and in vivo cell tracing revealed no evidences of muscle fibre fragmentation. In addition, our results indicate that this incomplete dedifferentiation was initiated by the retraction of muscle fibres. Conclusions Our results show that complete skeletal muscle dedifferentiation is less common than expected in lower vertebrates. In addition, the discovery of incomplete dedifferentiation in muscle fibres of the tadpole tail stresses the importance of coupling histological studies with in vivo cell tracing experiments to better understand the regenerative mechanisms. PMID:22369050

[Adaptive features of life history for space experiments seen in Rana tagoi tadpoles].

PubMed

Yamashita, Masamichi; Kobayashi, Ken-ichiro; Kashiwagi, Akihiko; Shigenari, Makiko; Wassersug, Richard J; Naitoh, Tomio

2002-11-01

We propose to use the physiological responses of tadpoles in space to study the effects of gravity at the organismal level. The tadpoles we propose for study, Rana tagoi, have naturally transparent abdominal walls, permitting viscera, such as heart and intestine, to be easily observed. Rana tagoi is a mountainous species that lays eggs in water, typically at crevasses in rocky substrates. Its eggs are rich in yolk, and tadpoles can grow without being fed (except own feces). However, they will eat when presented food. Coprophagy in these tadpoles can be clearly seen when small amount of food is fed. Abdominal wall remains transparent until metamorphosis. Intestinal and cardiac activity are clearly visible and can be documented by video without any invasive procedures. Because of the limited requirements on the digestive system in this species, their intestine does not elongate much when the tadpoles grow up. Even in this species, periodical contractions occur in the intestine throughout the larval period. Space experiments using R. tagoi tadpoles are promising in terms of scientific merit and technical feasibility. With this species it is possible to study the effects of gravity on visceral physiology and metamorphosis. Rana tagoi tadpoles would be a good model for space experiments where only the basic minimum capability of life support function (e.g., temperature and oxygen control), could be provided.

Tolerance to high temperature and salinity by tadpoles of the Philippine frog, Rana cancrivora

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dunson, W.A.

1977-05-25

Amphibians as a group are considered rather intolerant of temperatures above 38C. Tadpoles were found in Philippine tidal pools which were as hot as 42C near midday. This represents an increase of about 3C over the previously recorded high temperature for tadpole survival. Groups of tadpoles were collected and acclimated at 22 to 25C and 35C for 5 to 21 days. Survival time was measured at 40 to 45C at 20% sea water. Tadpoles acclimated at 35C survived much longer. At 42C survival was greater than 40 h. A further test of tadpole survival in dilutions of seawater was mademore » at 25C. Tadpoles were placed 5 days each at 0, 20, 40, 60, 80 and 100% sea water. The percentage dead at end of 5 day period was 0, 0, 0, 5, 33, and 100%. The survival was more than 50% up through 80% sea water. (MU)« less

The Tadpole and the Wriggler

NASA Image and Video Library

2014-04-14

A bright blue tadpole appears to swim through the inky blackness of space. Known as IRAS 20324+4057, but dubbed "the Tadpole," this clump of gas and dust has given birth to a bright, "protostar," one of the earliest steps in building a star. This image was taken by NASA's Hubble Space Telescope, and released publicly, in 2012. There are actually multiple protostars within this tadpole's 'head," but the glowing yellow one in this image is the most luminous and massive. When this protostar has gathered together enough mass from its surroundings, it will eventually emerge as a fully-fledged young star. The intense blue glow is caused by nearby stars firing ultraviolet radiation at IRAS 20324+4057, which also sculpts its tail into a long, wiggly shape. In total, this clump spans roughly a light-year from head to tail-tip, and contains gas weighing almost four times the mass of the sun. Framed against a background of distant stars, IRAS 20324+4057 is making its way through the Cygnus OB2 association, a loose cluster of stars some 4,700 light-years from Earth in the constellation Cygnus. This association is one of the largest clusters known, and is famed for its heavyweight members. It contains some of the hottest, most massive and most luminous stars known, some of which are about two million times more luminous than the sun. The Tadpole is not alone in this interstellar pond. Just out of view, to the bottom right of this image, lies another curious object dubbed "the Goldfish" by astronomers. The Goldfish is about half the length of IRAS 20324+4057, and is also thought to be a globule of gas that is being both lit up and sculpted by radiation from cluster stars. Completing this trio is a small clump of blue gas, informally nicknamed "the Wriggler" by some astronomers, visible in the bottom left of this Hubble image. All three objects have the same orientation in the sky and appear to be brighter on their northern sides, leading astronomers to believe they are being

Unearthing the Fossorial Tadpoles of the Indian Dancing Frog Family Micrixalidae.

PubMed

Senevirathne, Gayani; Garg, Sonali; Kerney, Ryan; Meegaskumbura, Madhava; Biju, S D

2016-01-01

Tadpoles of the monotypic Indian dancing frog family Micrixalidae have remained obscure for over 125 years. Here we report the discovery of the elusive tadpoles of Micrixalus herrei from the sand beds of a forested stream in southern Western Ghats, and confirm their identity through DNA barcoding. These actively burrowing tadpoles lead an entirely fossorial life from eggs to late metamorphic stages. We describe their internal and external morphological characters while highlighting the following features: eel-like appearance, extensively muscularized body and tail, reduced tail fins, skin-covered eyes, delayed development of eye pigmentation in early pre-metamorphic stages (Gosner stages 25-29), prominent tubular sinistral spiracle, large transverse processes on vertebrae II and III, ankylosed ribs on transverse processes of vertebra II, notochord terminating before the atlantal cotyle-occipital condyle junction, absence of keratodonts, serrated well-formed jaw sheaths, and extensive calcified endolymphatic sacs reaching sacrum posteriorly. The tadpole gut contains mostly fine sediments and sand. We discuss the eel-like morphology and feeding habits of M. herrei in the context of convergence with other well-known fossorial tadpoles. This discovery builds the knowledge base for further comparative analyses and conservation of Micrixalus, an ancient and endemic lineage of Indian frogs.

Unearthing the Fossorial Tadpoles of the Indian Dancing Frog Family Micrixalidae

PubMed Central

Senevirathne, Gayani; Garg, Sonali; Kerney, Ryan; Meegaskumbura, Madhava; Biju, S. D.

2016-01-01

Tadpoles of the monotypic Indian dancing frog family Micrixalidae have remained obscure for over 125 years. Here we report the discovery of the elusive tadpoles of Micrixalus herrei from the sand beds of a forested stream in southern Western Ghats, and confirm their identity through DNA barcoding. These actively burrowing tadpoles lead an entirely fossorial life from eggs to late metamorphic stages. We describe their internal and external morphological characters while highlighting the following features: eel-like appearance, extensively muscularized body and tail, reduced tail fins, skin-covered eyes, delayed development of eye pigmentation in early pre-metamorphic stages (Gosner stages 25–29), prominent tubular sinistral spiracle, large transverse processes on vertebrae II and III, ankylosed ribs on transverse processes of vertebra II, notochord terminating before the atlantal cotyle-occipital condyle junction, absence of keratodonts, serrated well-formed jaw sheaths, and extensive calcified endolymphatic sacs reaching sacrum posteriorly. The tadpole gut contains mostly fine sediments and sand. We discuss the eel-like morphology and feeding habits of M. herrei in the context of convergence with other well-known fossorial tadpoles. This discovery builds the knowledge base for further comparative analyses and conservation of Micrixalus, an ancient and endemic lineage of Indian frogs. PMID:27027870

The genotoxic effects of the imidacloprid-based insecticide formulation Glacoxan Imida on Montevideo tree frog Hypsiboas pulchellus tadpoles (Anura, Hylidae).

PubMed

Pérez-Iglesias, J M; Ruiz de Arcaute, C; Nikoloff, N; Dury, L; Soloneski, S; Natale, G S; Larramendy, M L

2014-06-01

The neonicotinoid insecticide imidacloprid (IMI) affects the insect central nervous system and is successfully applied to control pests for a variety of agricultural crops. In the current study, acute toxicity and genotoxicity of the IMI-containing commercial formulation insecticide Glacoxan Imida (35 percent IMI) was evaluated on Hypsiboas pulchellus (Anura: Hylidae) tadpoles exposed under laboratory conditions. A lethal effect was evaluated as the end point for lethality, whereas micronucleus (MN) frequency and DNA single-strand breaks evaluated by the single cell gel electrophoresis (SCGE) assay were employed as end points for genotoxicity. Sublethal end points were assayed within the 12.5-37.5mg/L IMI concentration range. Experiments were performed on tadpoles at stage 36 (range, 35-37) according to the classification proposed by Gosner. Lethality studies revealed an LC50 96h value of 52.622mg/L IMI. Increased frequency of MNs was only observed when 25.0mg/L was assayed for 96h, whereas no other nuclear abnormalities were induced. Increase of the genetic damage index was observed at 48h of treatment within the 12.5-37.5mg/L concentration range, whereas an increased frequency of DNA damage was observed only in tadpoles treated with 37.5mg/L IMI for 96h. This study represents the first evidence of the acute lethal and genotoxic effects exerted by IMI on tadpoles of an amphibian species native to Argentina under laboratory conditions. Copyright © 2014 Elsevier Inc. All rights reserved.

Molecular mechanisms of corticosteroid synergy with thyroid hormone during tadpole metamorphosis

PubMed Central

Bonett, Ronald M.; Hoopfer, Eric D.; Denver, Robert J.

2010-01-01

Corticosteroids (CS) act synergistically with thyroid hormone (TH) to accelerate amphibian metamorphosis. Earlier studies showed that CS increase nuclear 3,5,3′-triiodothyronine (T3) binding capacity in tadpole tail, and 5′ deiodinase activity in tadpole tissues, increasing the generation of T3 from thyroxine (T4). In the present study we investigated CS synergy with TH by analyzing expression of key genes involved in TH and CS signaling using tadpole tail explant cultures, prometamorphic tadpoles, and frog tissue culture cells (XTC-2 and XLT-15). Treatment of tail explants with T3 at 100 nM, but not at 10 nM caused tail regression. Corticosterone (CORT) at three doses (100, 500, 3400 nM) had no effect or increased tail size. T3 at 10 nM plus CORT caused tails to regress similar to 100 nM T3. Thyroid hormone receptor beta (TRβ) mRNA was synergistically upregulated by T3 plus CORT in tail explants, tail and brain in vivo, and tissue culture cells. The activating 5′ deiodinase type 2 (D2) mRNA was induced by T3 and CORT in tail explants and tail in vivo. Thyroid hormone increased expression of glucocorticoid (GR) and mineralocorticoid receptor (MR) mRNAs. Our findings support that the synergistic actions of TH and CS in metamorphosis occur at the level of expression of genes for TRβ and D2, enhancing tissue sensitivity to TH. Concurrently, TH enhances tissue sensitivity to CS by upregulating GR and MR. Environmental stressors can modulate the timing of tadpole metamorphosis in part by CS enhancing the response of tadpole tissues to the actions of TH. PMID:20338173

The relative importance of prey-borne and predator-borne chemical cues for inducible antipredator responses in tadpoles.

PubMed

Hettyey, Attila; Tóth, Zoltán; Thonhauser, Kerstin E; Frommen, Joachim G; Penn, Dustin J; Van Buskirk, Josh

2015-11-01

Chemical cues that evoke anti-predator developmental changes have received considerable attention, but it is not known to what extent prey use information from the smell of predators and from cues released through digestion. We conducted an experiment to determine the importance of various types of cues for the adjustment of anti-predator defences. We exposed tadpoles (common frog, Rana temporaria) to water originating from predators (caged dragonfly larvae, Aeshna cyanea) that were fed different types and quantities of prey outside of tadpole-rearing containers. Variation among treatments in the magnitude of morphological and behavioural responses was highly consistent. Our results demonstrate that tadpoles can assess the threat posed by predators through digestion-released, prey-borne cues and continually released predator-borne cues. These cues may play an important role in the fine-tuning of anti-predator responses and significantly affect the outcome of interactions between predators and prey in aquatic ecosystems. There has been much confusion regards terminology used in the literature, and therefore we also propose a more precise and consistent binomial nomenclature based on the timing of chemical cue release (stress-, attack-, capture-, digestion- or continually released cues) and the origin of cues (prey-borne or predator-borne cues). We hope that this new nomenclature will improve comparisons among studies on this topic.

Maternally derived chemical defences are an effective deterrent against some predators of poison frog tadpoles (Oophaga pumilio).

PubMed

Stynoski, Jennifer L; Shelton, Georgia; Stynoski, Peter

2014-05-01

Parents defend their young in many ways, including provisioning chemical defences. Recent work in a poison frog system offers the first example of an animal that provisions its young with alkaloids after hatching or birth rather than before. But it is not yet known whether maternally derived alkaloids are an effective defence against offspring predators. We identified the predators of Oophaga pumilio tadpoles and conducted laboratory and field choice tests to determine whether predators are deterred by alkaloids in tadpoles. We found that snakes, spiders and beetle larvae are common predators of O. pumilio tadpoles. Snakes were not deterred by alkaloids in tadpoles. However, spiders were less likely to consume mother-fed O. pumilio tadpoles than either alkaloid-free tadpoles of the red-eyed treefrog, Agalychnis callidryas, or alkaloid-free O. pumilio tadpoles that had been hand-fed with A. callidryas eggs. Thus, maternally derived alkaloids reduce the risk of predation for tadpoles, but only against some predators. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Long-term effects of pesticide exposure at various life stages of the southern leopard frog (Rana sphenocephala)

USGS Publications Warehouse

Bridges, C.M.

2000-01-01

Amphibian larvae are commonly exposed to low levels of pesticides during their development. Chronic studies generally examine the effects of long-term exposure, but they often disregard the importance of the individual life stage at which tadpoles are exposed. I determined the point during development at which carbaryl effects are manifested by exposing southern leopard frog tadpoles (Rana sphenocephala) to the pesticide carbaryl at five different times during development. Metamorphs exposed throughout the tadpole stage and throughout development (egg, embryo, tadpole) experienced significant mortality at all chemical levels. Although the length of the larval period was the same for all experimental groups, metamorphs exposed during the egg stage were smaller than their corresponding controls, independent of whether they were exposed at any other stage. Nearly 18% of individuals exposed to carbaryl during development exhibited some type of developmental deformity (including both visceral and limb malformities), compared to a single deformed (< 1%) control tadpole, demonstrating that a chemical hypothesis for amphibian deformities remains viable. Because exposure to nonpersistent chemicals may last for only a short period of time, it is important to examine the long-term effects that short-term exposure has on larval amphibians and the existence of any sensitive life stage. Any delay in metamorphosis or decrease in size at metamorphosis can impact demographic processes of the population, potentially leading to declines or local extinction.

SHOCKED AND SCORCHED: THE TAIL OF A TADPOLE IN AN INTERSTELLAR POND

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sahai, R.; Morris, M. R.; Claussen, M. J., E-mail: raghvendra.sahai@jpl.nasa.gov

2012-05-20

We report multi-wavelength observations of the far-infrared source IRAS 20324+4057, including high-resolution optical imaging with the Hubble Space Telescope, and ground-based near-infrared, millimeter-wave and radio observations. These data show an extended, limb-brightened, tadpole-shaped nebula with a bright, compact, cometary nebula located inside the tadpole head. Our molecular line observations indicate that the Tadpole is predominantly molecular with a total gas mass exceeding 3.7 M{sub Sun }. Our radio continuum imaging and archival Spitzer IRAC images show the presence of additional tadpole-shaped objects in the vicinity of IRAS 20324+4057 that share a common east-west head-tail orientation: we propose that these structuresmore » are small, dense molecular cores that originated in the Cygnus cloud and are now being (1) photoevaporated by the ultraviolet radiation field of the Cyg OB2 No. 8 cluster located to the northwest; and (2) shaped by ram pressure of a distant wind source or sources located to the west, blowing ablated and photoevaporated material from their heads eastward. The ripples in the tail of the Tadpole are interpreted in terms of instabilities at the interface between the ambient wind and the dense medium of the former.« less

Does corticosterone mediate predator-induced responses of larval Hylarana indica?

PubMed

Joshi, A M; Wadekar, N V; Gramapurohit, N P

2017-09-15

Prey-predator interactions have been studied extensively in terms of morphological and behavioural responses of prey to predation risk using diverse model systems. However, the underlying physiological changes associated with morphological, behavioural or life historical responses have been rarely investigated. Herein, we studied the effect of chronic predation risk on larval growth and metamorphosis of Hylarana indica and the underlying physiological changes in prey tadpoles. In the first experiment, tadpoles were exposed to a caged predator from Gosner stage 25-42 to record growth and metamorphosis. Further, whole body corticosterone (CORT) was measured to determine the physiological changes underlying morphological and life historical responses of these prey tadpoles. Surprisingly, tadpoles experiencing continuous predation risk grew and developed faster and metamorphosed at a larger size. Interestingly, these tadpoles had significantly lower CORT levels. In the second experiment, tadpoles were exposed to predation risk (PR) or PR+CORT from stage 25-42 to determine the role of CORT in mediating predator-induced responses of H. indica. Tadpoles facing continuous predation risk grew and developed faster and metamorphosed at a larger size reinforcing the results of the first experiment. However, when CORT was administered along with predation risk, tadpoles grew and developed slowly leading to delayed metamorphosis. Interestingly, growth and metamorphic traits of tadpoles exposed to PR+CORT were comparable to those of the control group indicating that exogenous CORT nullified the positive effect of predation risk. Apparently, CORT mediates predator-induced morphological responses of H. indica tadpoles by regulating their physiology. Copyright © 2016 Elsevier Inc. All rights reserved.

Foraging behaviour in tadpoles of the bronze frog Rana temporalis: experimental evidence for the ideal free distribution.

PubMed

Veeranagoudar, Dheeraj K; Shanbhag, Bhagyashri A; Saidapur, Srinivas K

2004-06-01

The ability of bronze frog Rana temporalis tadpoles (pure or mixed parental lines) to assess the profitability of food habitats and distribute themselves accordingly was tested experimentally using a rectangular choice tank with a non- continuous input design. Food (boiled spinach) was placed at two opposite ends of the choice tank in a desired ratio (1 : 1, 1 : 2 or 1 : 4) to create habitat A and B. The tadpoles in Gosner stage 28-33, pre-starved for 24 h, were introduced in an open ended mesh cylinder placed in the center of the choice tank, held for 4 min (for acclimation) and then released to allow free movement and habitat selection. The number of tadpoles foraging at each habitat was recorded at 10, 15, 20, 25 and 30 min time intervals. The actual suitability, Si (the food available in a habitat after colonization of tadpoles) of each habitat was obtained from the equation Si = Bi - fi (di) where Bi is basic suitability (amount of food provided at each habitat before release of tadpoles), fi is the rate of depletion of food (lowering effect) with introduction of each tadpole, and di is the density of tadpoles in habitat i. The expected number of tadpoles at each habitat was derived from the actual suitability. With no food in the choice tank, movement of the tadpoles in the test arena was random indicating no bias towards any end of the choice tank or the procedure. In tests with a 1 : 1 food ratio, the observed ratio of tadpoles (11.71 : 12.28) was comparable with the expected 12 : 12 ratio. The observed number of tadpoles in the habitats with a 1 : 2 food ratio was 8.71 : 15.29 and 7.87 : 16.13 for pure and mixed parental lines respectively. In both cases, the observed ratios were close to the expected values (7 : 17). Likewise, in experiments with a 1 : 4 food ratio, the observed number of tadpoles in the two habitats (10.78 : 37.22) did not differ significantly from the expected ratio of 7 : 41. In all tests, the number of R. temporalis tadpoles matched

Impact of ammonium nitrate and sodium nitrate on tadpoles of Alytes obstetricans.

PubMed

Garriga, Núria; Montori, A; Llorente, G A

2017-07-01

The presence of pesticides, herbicides and fertilisers negatively affect aquatic communities in general, and particularly amphibians in their larval phase, even though sensitivity to pollutants is highly variable among species. The Llobregat Delta (Barcelona, Spain) has experienced a decline of amphibian populations, possibly related to the reduction in water quality due to the high levels of farming activity, but also to habitat loss and alteration. We studied the effects of increasing ammonium nitrate and sodium nitrate levels on the survival and growth rate of Alytes obstetricans tadpoles under experimental conditions. We exposed larvae to increasing concentrations of nitrate and ammonium for 14 days and then exposed them to water without pollutants for a further 14 days. Only the higher concentrations of ammonium (>33.75 mg/L) caused larval mortality. The growth rate of larvae was reduced at ≥22.5 mg/L NH 4 + , although individuals recovered and even increased their growth rate once exposure to the pollutant ended. The effect of nitrate on growth rate was detected at ≥80 mg/L concentrations, and the growth rate reduction in tadpoles was even observed during the post-exposure phase. The concentrations of ammonium with adverse effects on larvae are within the range levels found in the study area, while the nitrate concentrations with some adverse effect are close to the upper range limit of current concentrations in the study area. Therefore, only the presence of ammonium in the study area is likely to be considered of concern for the population of this species, even though the presence of nitrate could cause some sublethal effects. These negative effects could have an impact on population dynamics, which in this species is highly sensitive to larval mortality due to its small clutch size and prolonged larval period compared to other anuran amphibians.

Descriptions and biological notes on three unusual mantellid tadpoles (Amphibia: Anura: Mantellidae) from southeastern Madagascar

USGS Publications Warehouse

Altig, R.; McDiarmid, R.W.

2006-01-01

The morphologies of three unusual tadpoles from slow-flowing, sandy-bottomed, rain forest streams in southeastern Madagascar are described. The large oral apparatus of the tadpole of Boophis picturatus Glaw, Vences, Andreone, and Vallan, 2001 lacks all keratinized structures and has an elaborately-folded lower labium with five, radially oriented, flattopped ridges. The tadpole of Mantidactylus guttulatus (Boulenger, 1881) lacks all keratinized mouthparts and has three immense papillae where the upper jaw normally occurs. The tadpole of Mantidactylus lugubris (Dumeril, 1853) has an ornate oral apparatus involving greatly hypertrophied derivatives of jaw serrations and unique structures on the lower labium that resemble labial teeth.

Pond tadpoles with generalized morphology: is it time to reconsider their functional roles in aquatic communities?

PubMed

Petranka, James W; Kennedy, Caroline A

1999-09-01

With rare exceptions, anuran larvae have traditionally been considered to occupy lower trophic levels in aquatic communities where they function as microphagous suspension feeders. This view is being challenged by studies showing that tadpoles with generalized morphology often function as macrophagous predators. Here, we review the literature concerning macrophagy by tadpoles and provide two additional examples involving generalized tadpoles. In the first, we demonstrate with laboratory and field experiments that wood frog (Rana sylvatica) tadpoles are major predators of macroinvertebrates in ponds. In the second, we show that green frog (R. clamitans) tadpoles can cause catastrophic reproductive failure of the wood frog via egg predation. These results and data from other studies challenge the assumption that generalized tadpoles function as filter-feeding omnivores, and question the general applicability of community organization models which assume that predation risk increases with pond permanence. We suggest that predation risk is greater in temporary ponds than in more permanent ponds for many organisms that are vulnerable to predation by tadpoles. This being so, a conditional model based upon interactions that are species-specific, life-stage-specific, and context-dependent may better explain community organization along hydrological gradients than models which assume that temporary ponds have few or no predators.

Effects of tannin source and concentration from tree leaves on two species of tadpoles.

PubMed

Earl, Julia E; Semlitsch, Raymond D

2015-01-01

Vegetation in and around freshwater ecosystems can affect aquatic organisms through the production of secondary compounds, which are retained in leaves after senescence and are biologically active. Tannins can be toxic to tadpoles, but the plant source of tannins and tannin concentration have been confounded in experimental designs in previous studies. To examine the effects of the concentration and source of tannins (tree species), we examined the effects of 4 factors on tadpole survival, growth, and development: tannin source (red oak [Quercus rubra], white oak [Quercus alba], or sugar maple [Acer saccharum]); tannin concentration (including a control); diet protein level; and tadpole species (American toad [Anaxyrus americanus] and spring peepers [Pseudacris crucifer]). Tannin source and concentration affected spring peeper survival, but American toads had uniformly high survival. Spring peepers had a lower survival rate in high tannin concentrations of oak leachate but a high survival rate in both concentrations of sugar maple leachate. These differences in survival did not correspond with changes in dissolved oxygen, and no effect of dietary protein level on tadpole performance was observed. The presence of plant leachate resulted in increased tadpole growth in both species, but the mechanism for this finding is unclear. The results of the present study show that tannin concentration and source are important factors for tadpole performance, adding further evidence that plant chemistry can affect aquatic organisms. © 2014 SETAC.

Frugal cannibals: how consuming conspecific tissues can provide conditional benefits to wood frog tadpoles ( Lithobates sylvaticus)

NASA Astrophysics Data System (ADS)

Jefferson, Dale M.; Hobson, Keith A.; Demuth, Brandon S.; Ferrari, Maud C. O.; Chivers, Douglas P.

2014-04-01

Tadpoles show considerable behavioral plasticity. When population densities become high, tadpoles often become cannibalistic, likely in response to intense competition. Conspecific tissues are potentially an ideal diet by composition and should greatly improve growth and development. However, the potential release of alarm cues from the tissues of injured conspecifics may act to deter potential cannibals from feeding. We conducted multiple feeding experiments to test the relative effects that a diet of conspecifics has on tadpole growth and development. Results indicate that while conspecific tissues represent a better alternative to starvation and provide some benefits over low-protein diets, such a diet can have detrimental effects to tadpole growth and/or development relative to diets of similar protein content. Additionally, tadpoles raised individually appear to avoid consuming conspecific tissues and may continue to do so until they suffer from the effects of starvation. However, tadpoles readily fed upon conspecific tissues immediately when raised with competitors. These results suggest that cannibalism may occur as a result of competition rather than the specific quality of available diets, unless such diets lead to starvation.

Effects of density on growth, metamorphosis, and survivorship in tadpoles of Scaphiopus holbrooki

DOE Office of Scientific and Technical Information (OSTI.GOV)

Semlitsch, R.D.; Caldwell, J.P.

1982-08-01

Density-dependent aspects of growth, metamorphosis, and survivorship of Scaphiopus holbrooki tadpoles were examined in the laboratory under two experimental regimes. In the first density experiment, the growth index (W) of tadpoles decreased exponentially with density. Mean growth rate varied from 0.023 mL/d at the lowest density to 0.006 mL/d at the highest density. The mean number of days to metamorphic climax was positively associated with the initial density treatment: 27 d at the lowest density to 86 d at the highest density. The body size of tadpoles at metamorphosis showed a concave curvilinear relationship to initial density, indicating tadpoles atmore » the highest densities are apparently capable to growth recovery once released from density stress. The survival of tadpoles decreased exponentially with initial density, from 90% at the lowest density to 20% at the highest initial density. In the second experiment a cross-classified design was used to examine the effects of density and duration of treatment (time) on growth and metamorphosis. Density and time had significant effects on body size at metamorphosis and days to metamorphosis. There was no significant interaction between density and time. These results indicate that the inhibitory effect of density stress varies with the duration of the stress. Scaphiopus holbrooki tadpoles exhibit developmental traits (rapid growth, short larval period, small body size at metamorphosis) that should be favored by natural selection in high density habitats. Dispersability may be a mechanism whereby S. holbrooki can minimize the detrimental effects of density stress.« less

EVIDENCE FOR ACCELERATED METAMORPHOSIS IN BULLFROG (RANA CATESBIEANA) TADPOLES IN AN EPHEMERAL POND

EPA Science Inventory

It has been widely accepted that time to metamorphosis for non-native bullfrog tadpoles in the Pacific Northwest is greater than one year. We surveyed 22 ponds within the EE Wilson Reserve (Benton County, Oregon) for bullfrog tadpoles and metamorphs from April through September, ...

Lethal and sublethal effects of cypermethrin to Hypsiboas pulchellus tadpoles.

PubMed

Agostini, M Gabriela; Natale, Guillermo S; Ronco, Alicia E

2010-11-01

The study of the effects of the insecticide cypermethrin (CY) technical grade and its Sherpa® commercial formulation on Hypsiboas pulchellus tadpoles assessing lethality, behavior, growth, and abnormalities under standardized laboratory conditions is reported. Observed behaviors were identified and categorized by means of a ranking system according to the loss of mobility. Results of acute lethal effects indicate higher potency for Sherpa® at this level of assessment. All effects on behavior showed an increasing degree of injury as insecticide concentration increased. Organisms exposed to technical grade CY showed lower body length with respect to controls from 3.44 µg CY/L to higher concentrations, whereas those exposed to Sherpa® exhibited lower growth from 0.83 µg CY/L. Both forms of the tested insecticide caused abnormalities between 0.34 and 4.18 µg CY/L, but 100% of malformed individuals was detected from 34.4 µg CY/L for those exposed to the technical grade CY, and from 8.36 µg CY/L for those exposed to Sherpa®. This study proposes the use of easily identifiable and distinguishable sublethal end-points. The high input loads of CY in natural environments, the detected concentrations in the field, in addition to the low levels of this insecticide required to induce sublethal effects (which could eventually lead to death), allow for the conclusion that the insecticide is a risk factor for amphibians inhabiting agroecosystems.

Patterns of Batrachochytrium dendrobatidis transmission between tadpoles in a high-elevation rainforest stream in tropical Australia.

PubMed

Hagman, Mattias; Alford, Ross A

2015-08-20

The highly virulent fungal pathogen Batrachochytrium dendrobatidis (Bd) poses a global threat to amphibian biodiversity. Streams and other water bodies are central habitats in the ecology of the disease, particularly in rainforests where they may transport and transmit the pathogen and harbor infected tadpoles that serve as reservoir hosts. We conducted an experiment using larval green-eyed tree frogs Litoria serrata in semi-natural streamside channels to test the hypotheses that (1) the fungus can be transmitted downstream in stream habitats and (2) infection affects tadpole growth and mouthpart loss. Our results showed that transmission can occur downstream in flowing water with no contact between individuals, that newly infected tadpoles suffered increased mouthpart loss in comparison with controls that were never infected and that infected tadpoles grew at reduced rates. Although recently infected tadpoles showed substantial loss of mouthparts, individuals with longstanding infections did not, suggesting that mouthparts may re-grow following initial loss. Our study suggests that any management efforts that can reduce the prevalence of infections in tadpoles may be particularly effective if applied in headwater areas, as their effects are likely to be felt downstream.

Expression of Skin Patterns in Metamorphosing Tadpoles.

ERIC Educational Resources Information Center

Bagnara, Joseph T.; And Others

1985-01-01

Explains an experiment in which the rotation of a patch of skin on a tadpole results in a frog with rotated spots, proving that the spot pattern is determined long before it becomes visible. Procedures used are included. (DH)

A quantitative adverse outcome pathway model for thyroid axis disruption in Xenopus laevis tadpoles

EPA Science Inventory

The development of Xenopus laevis tadpoles is tightly controlled by the thyroid hormones tetraiodothyronine (T4) and triiodothyronine (T3). Toxicity testing efforts have shown that several compounds interfere with development in X. laevis tadpoles by disrupting the thyroid axis a...

Tadpole transport logistics in a Neotropical poison frog: indications for strategic planning and adaptive plasticity in anuran parental care.

PubMed

Ringler, Eva; Pašukonis, Andrius; Hödl, Walter; Ringler, Max

2013-11-09

Individuals should aim to adjust their parental behaviours in order to maximize the success of their offspring but minimize associated costs. Plasticity in parental care is well documented from various bird, mammal and fish species, whereas amphibians were traditionally assumed as being highly instinct-bound. Therefore, little is known about 'higher' cognitive abilities of amphibians, such as strategic planning and behavioural flexibility. Dendrobatid frogs have evolved a remarkable diversity of parental behaviours. The most noticeable of these behaviours is tadpole transport, which is obligatory in almost all species. Nonetheless, there is limited knowledge about spatial and temporal patterns of tadpole transport and the possible existence of behavioural plasticity on the individual level. In this study, we investigated correlates of tadpole transport behaviour in a natural population of the dendrobatid frog Allobates femoralis during five years. Tadpole transport was predominantly observed during morning hours. Although tadpoles were carried almost exclusively by males (N = 119), we also observed ten females performing this task. The parentage analysis revealed that in all cases females transported their own offspring. In contrast, four tadpole-carrying males were not the genetic fathers of the larvae they were transporting. The average clutch size of 20 eggs and our observation of an average of 8 tadpoles on the back of transporting individuals indicate that frogs do not carry entire clutches at once, and/or that they distribute their larvae across several water bodies. Contrary to the predictions from a hypothetical random search for deposition sites, the number of transported tadpoles was higher in males that travelled over longer distances. Our results suggest a strong selective pressure on males to shift the time invested in tadpole transport to periods of low intra-specific competition. The number of tadpoles on the back of the males significantly

A small increase in UV-B increases the susceptibility of tadpoles to predation

PubMed Central

Alton, Lesley A.; Wilson, Robbie S.; Franklin, Craig E.

2011-01-01

Increased ultraviolet-B (UV-B) radiation as a consequence of ozone depletion is one of the many potential drivers of ongoing global amphibian declines. Both alone and in combination with other environmental stressors, UV-B is known to have detrimental effects on the early life stages of amphibians, but our understanding of the fitness consequences of these effects remains superficial. We examined the independent and interactive effects of UV-B and predatory chemical cues (PCC) on a suite of traits of Limnodynastes peronii embryos and tadpoles, and assessed tadpole survival time in a predator environment to evaluate the potential fitness consequences. Exposure to a 3 to 6 per cent increase in UV-B, which is comparable to changes in terrestrial UV-B associated with ozone depletion, had no effect on any of the traits measured, except survival time in a predator environment, which was reduced by 22 to 28 per cent. Exposure to PCC caused tadpoles to hatch earlier, have reduced hatching success, have improved locomotor performance and survive for longer in a predator environment, but had no effect on tadpole survival, behaviour or morphology. Simultaneous exposure to UV-B and PCC resulted in no interactive effects. These findings demonstrate that increased UV-B has the potential to reduce tadpole fitness, while exposure to PCCs improves their fitness. PMID:21270039

The tadpole of Hypsiboas guentheri (Boulenger) (Anura: Hylidae).

PubMed

Almeida-Silva, Diego; Neto, Antonio Mollo; Mendes, Humberto Fonseca; Verdade, Vanessa Kruth

2016-10-28

Hypsiboas guentheri is a species of treefrog that inhabits the surrounding vegetation of temporary and permanent ponds at the coastal region of Southern Brazil, in the States of Santa Catarina and Rio Grande do Sul (Langone 1997; Frost 2016). It belongs to the H. pulchellus species group (Faivovich et al. 2004, Duellman et al. 2016), this group contains 39 species (Frost 2016), but formal descriptions of tadpoles are missing for 15 of them (Kolenc et al. 2008; Pinheiro et al., 2016). Herein we describe tadpoles of H. guentheri collected in February 2014 in the accumulated water on an underpass for wildlife crossing at the RS-486 highway (29º30'44.8" S 50º06'29.9" W), Itati municipality, Rio Grande do Sul State, Brazil.

Effects of CFT Legumine (5% Rotenone) on tadpole survival and metamorphosis of Chiricahua leopard frogs Lithobates chiricahuensis, Northern leopard frogs L. pipiens, and American bullfrogs L. catesbeianus

USGS Publications Warehouse

Alvarez, Guillermo; Caldwell, Colleen A.; Kruse, Carter G.

2017-01-01

Amphibians may experience collateral effects if exposed to CFT Legumine (5% rotenone), a piscicide that is used to remove invasive fish. A series of 48-h static toxicity tests assessed the acute effects of CFT Legumine on multi-aged tadpoles of the federally listed Chiricahua leopard frog Lithobates chiricahuensis, the widespread northern leopard frog L. pipiens, and the increasingly invasive American bullfrog L. catesbeianus. At the earliest Gosner stages (GS 21–25), Chiricahua leopard frogs were more sensitive to CFT Legumine (median lethal concentration [LC50] = 0.41–0.58 mg/L) than American bullfrogs (LC50 = 0.63–0.69 mg/L) and northern leopard frogs (LC50 = 0.91 and 1.17 mg/L). As tadpoles developed (i.e., increase in GS), their sensitivity to rotenone decreased. In a separate series of 48-h static nonrenewal toxicity tests, tadpoles (GS 21–25 and GS 31–36) of all three species were exposed to piscicidal concentrations of CFT Legumine (0.5, 1.0, and 2.0 mg/L) to assess postexposure effects on metamorphosis. In survivors of all three species at both life stages, the time to tail resorption was nearly doubled in comparison with that of controls. For example, mid-age (GS 31–36) Chiricahua leopard frog tadpoles required 210.7 h to complete tail resorption, whereas controls required 108.5 h. However, because tail resorption is a relatively short period in metamorphosis, the total duration of development (days from posthatch to complete metamorphosis) and the final weight did not differ in either age-group surviving nominal concentrations of 0.5-, 1.0-, and 2.0-mg/L CFT Legumine relative to controls. This research demonstrates that the CFT Legumine concentrations commonly used in field applications to remove unwanted fish could result in considerable mortality of the earliest stages of Lithobates species. In addition to acute lethality, piscicide treatments may result in delayed tail resorption, which places the tadpoles at risk by increasing

A putative functional vomeronasal system in anuran tadpoles

PubMed Central

Jungblut, Lucas David; Pozzi, Andrea Gabriela; Paz, Dante Agustín

2012-01-01

We investigated the occurrence and anatomy of the vomeronasal system (VNS) in tadpoles of 13 different anuran species. All of the species possessed a morphologically fully developed VNS with a highly conserved anatomical organisation. We found that a bean-shaped vomeronasal organ (VNO) developed early in the tadpoles, during the final embryonic stages, and was located in the anteromedial nasal region. Histology revealed the presence of bipolar chemosensory neurones in the VNO that were immunoreactive for the Gαo protein. Tract-tracing experiments demonstrated that chemosensory neurones from the VNO reach specific areas in the brain, where a discernible accessory olfactory bulb (AOB) could be observed. The AOB was located in the ventrolateral side of the anterior telencephalon, somewhat caudal to the main olfactory bulb. Synaptophysin-like immunodetection revealed that synaptic contacts between VNO and AOB are established during early larval stages. Moreover, using lectin staining, we identified glomerular structures in the AOB in most of the species that we examined. According to our findings, a significant maturation in the VNS is achieved in anuran larvae. Recent published evidence strongly suggests that the VNS appeared early in vertebrate evolution and was already present in the aquatic last common ancestor of lungfish and tetrapods. In this context, tadpoles may be a good model in which to investigate the anatomical, biochemical and functional aspects of the VNS in an aquatic environment. PMID:22774780

Toxicity of the conventional energetics TNT and RDX relative to new insensitive munitions constituents DNAN and NTO in Rana pipiens tadpoles.

PubMed

Stanley, Jacob K; Lotufo, Guilherme R; Biedenbach, James M; Chappell, Pornsawan; Gust, Kurt A

2015-04-01

An initiative within the US military is targeting the replacement of traditional munitions constituents with insensitive munitions to reduce risk of accidental detonation. The purpose of the present study was to comparatively assess toxicity of the traditional munitions constituents 2,4,6-trinitrotoluene (TNT) and 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) with the new insensitive munitions constituents 2,4-dinitroanisole (DNAN) and 3-nitro-1,2,4-triazol-5-one (NTO). The following exposure durations were performed with Rana pipiens (leopard frog) tadpoles: TNT and DNAN, 96 h and 28 d; RDX, 10 d and 28 d; NTO, 28 d. The 96-h 50% lethal concentration (LC50) values and 95% confidence intervals for TNT and DNAN were 4.4 mg/L (4.2 mg/L, 4. 7 mg/L) and 24.3 mg/L (21.3 mg/L, 27.6 mg/L), respectively. No significant impacts on survival were observed in the 10-d exposure to RDX up to 25.3 mg/L. Effects on tadpole swimming distance were observed with a lowest-observed-effect concentration (LOEC) of 5.9 mg/L RDX. In the 28-d exposures, the LOECs for survival for TNT, DNAN, and NTO were 0.003 mg/L, 2.4 mg/L, and 5.0 mg/L, respectively. No significant mortality was observed in the RDX chronic 28-d exposure up to the highest treatment level tested of 28.0 mg/L. Neither tadpole developmental stage nor growth was significantly affected in any of the 28-d exposures. Rana pipiens were very sensitive to chronic TNT exposure, with an LOEC 3 orders of magnitude lower than those for insensitive munitions constituents DNAN and NTO. © 2015 SETAC.

Evaluation of imazethapyr-induced DNA oxidative damage by alkaline Endo III- and Fpg-modified single-cell gel electrophoresis assay in Hypsiboas pulchellus tadpoles (Anura, Hylidae).

PubMed

Pérez-Iglesias, Juan Manuel; Ruiz de Arcaute, Celeste; Natale, Guillermo S; Soloneski, S; Larramendy, Marcelo L

2017-08-01

Imazethapyr (IMZT) is a selective postemergent herbicide with residual action. Available data analyzing its effects in aquatic vertebrates are scarce. In previous studies, we demonstrated that IMZT induces lesions into the DNA of Hypsiboas pulchellus tadpoles using the single-cell gel electrophoresis (SCGE) assay as a biomarker for genotoxicity. Currently, this assay can be modified by including incubation with lesion-specific endonucleases, e.g., endonuclease III (Endo III) and formamidopyrimidine-DNA glycosylase (Fpg), which detect oxidized pyrimidine and purine bases, respectively. The aim of this study was to evaluate the role of oxidative stress in the genotoxic damage in circulating blood cells of H. pulchellus tadpoles exposed to the IMZT-based Pivot H ® formulation (10.59% IMZT) at a concentration equivalent to 25% of the LC 50 (96h) value (0.39mg/L IMZT) during 48 and 96h. Our results demonstrate that the herbicide induces oxidative DNA damage on H. pulchellus tadpoles at purines bases but not at pyrimidines. Our findings represent the first evidence of oxidative damage caused by IMZT on anuran DNA using the alkaline restriction enzyme-modified SCGE assay. Copyright © 2017 Elsevier Inc. All rights reserved.

Thyroid Hormone Receptor α- and β-Knockout Xenopus tropicalis Tadpoles Reveal Subtype-Specific Roles During Development.

PubMed

Nakajima, Keisuke; Tazawa, Ichiro; Yaoita, Yoshio

2018-02-01

Thyroid hormone (TH) binds TH receptor α (TRα) and β (TRβ) to induce amphibian metamorphosis. Whereas TH signaling has been well studied, functional differences between TRα and TRβ during this process have not been characterized. To understand how each TR contributes to metamorphosis, we generated TRα- and TRβ-knockout tadpoles of Xenopus tropicalis and examined developmental abnormalities, histology of the tail and intestine, and messenger RNA expression of genes encoding extracellular matrix-degrading enzymes. In TRβ-knockout tadpoles, tail regression was delayed significantly and a healthy notochord was observed even 5 days after the initiation of tail shortening (stage 62), whereas in the tails of wild-type and TRα-knockout tadpoles, the notochord disappeared after ∼1 day. The messenger RNA expression levels of genes encoding extracellular matrix-degrading enzymes (MMP2, MMP9TH, MMP13, MMP14, and FAPα) were obviously reduced in the tail tip of TRβ-knockout tadpoles, with the shortening tail. The reduction in olfactory nerve length and head narrowing by gill absorption were also affected. Hind limb growth and intestinal shortening were not compromised in TRβ-knockout tadpoles, whereas tail regression and olfactory nerve shortening appeared to proceed normally in TRα-knockout tadpoles, except for the precocious development of hind limbs. Our results demonstrated the distinct roles of TRα and TRβ in hind limb growth and tail regression, respectively. Copyright © 2018 Endocrine Society.

UV-B affects the immune system and promotes nuclear abnormalities in pigmented and non-pigmented bullfrog tadpoles.

PubMed

Franco-Belussi, Lilian; Fanali, Lara Zácari; De Oliveira, Classius

2018-03-01

Ultra-Violet (UV) radiation is a stressor of the immune system and causes DNA damage. Leukocytes can change in response to environmental changes in anurans, making them an important biomarker of stressful situations. The initial barrier against UV in ectothermic animals is melanin-containing cells in skin and in their internal organs. Here, we tested the effects of UV exposure on immune cells and DNA integrity in pigmented and non-pigmented tadpoles of Lithobates catesbeianus. We used an inflammation model with lipopolysaccharide (LPS) of Escherichia coli to test synergic effects of UV and LPS. We tested the following hypotheses: 1) DNA damage caused by UV will be more pronounced in non-pigmented than in pigmented animals; 2) LPS increases leukocytes in both pigmented and non-pigmented animals by systemic inflammation; 3) The combined LPS and UV exposure will decrease the number of leukocytes. We found that the frequency of immune cells differed between pigmented and non-pigmented tadpoles. UV exposure increased mast cells and DNA damage in erythrocytes in both pigmented and non-pigmented tadpoles, while leukocytes decreased after UV exposure. Non-pigmented tadpoles experienced DNA damage and a lower lymphocyte count earlier than pigmented tadpoles. UV altered immune cells likely as a consequence of local and systemic inflammation. These alterations were less severe in pigmented than in non-pigmented animals. UV and LPS increased internal melanin in pigmented tadpoles, which were correlated with DNA damage and leukocytes. Here, we described for the first time the effects of UV and LPS in immune cells of pigmented and non-pigmented tadpoles. In addition, we demonstrated that internal melanin in tadpoles help in these defenses, since leukocyte responses were faster in non-pigmented animals, supporting the hypothesis that melanin is involved in the initial innate immune response. Copyright © 2018 Elsevier B.V. All rights reserved.

Studying the Physiology of Tadpoles through their Naturally Transparent Abdomen Walls

NASA Astrophysics Data System (ADS)

Naitoh, T.; Yamashita, M.; Wassersug, R.

Because their development is external and they grow rapidly, anurans (frogs and toads) have been important model species in studies of how spaceflight affects vertebrate development. However the long term effects of spaceflight on post embryonic stages have barely been studied in these, or for that matter, any other vertebrate species. Tadpoles of certain species have naturally transparent skin covering a large portion of their ventral abdomen wall. Consequently viscera and visceral movements can be observed through this window without any invasive treatment to the animals. Respiration rate (as measured by buccal floor movements), heart rate, and gut motility are all indices of physiological state that can be observed in unconstrained larvae of these particular anuran species. We are using changes in these physiological variables to study the responses of tadpoles to changes in their external environment. Our study of the physiological responses of these tadpoles to microgravity has been selected as a candidate spaceflight experiment (to be housed in the Canadian Aquatic Research Facility). Ground-based studies with these same larvae are currently underway. Those experiments make use of stepwise changes in temperature as a stimulus to document the effect of temperature on intestinal motility in tadpoles. The scope of our studies on gravitational physiology and key issues in post- embryonic development of anurans are the focus of our presentation. This research is a prelude to raising a vertebrate through a complete life cycle in the space environment.

Overwintered Bullfrog tadpoles negatively affect Salamanders and Anurans in native amphibian communities

USGS Publications Warehouse

Boone, M.D.; Little, E.E.; Semlitsch, R.D.

2004-01-01

We examined the interactive effects of overwintered Bullfrog (Rana catesbeiana) tadpoles and pond hydroperiod on a community of larval amphibians in outdoor mesocosms including American Toads (Bufo americanus), Southern Leopard Frogs (Rana sphenocephala), and Spotted Salamanders (Ambystoma maculatum) - species within the native range of Bullfrogs. Spotted Salamanders and Southern Leopard Frogs were negatively influenced by the presence of overwintered Bullfrogs. Spotted Salamanders had shorter larval periods and slightly smaller masses at metamorphosis, and Southern Leopard Frogs had smaller masses at metamorphosis when reared with Bullfrogs than without. Presence of overwintered Bullfrogs, however, did not significantly affect American Toads. Longer pond hydroperiods resulted in greater survival, greater size at metamorphosis, longer larval periods, and later time until emergence of the first metamorphs for Southern Leopard Frog tadpoles and Spotted Salamander larvae. Our study demonstrated that overwintered Bullfrog tadpoles can respond to changing pond hydroperiods and can negatively impact metamorphosis of native amphibians.

Induction of micronuclei and nuclear abnormalities in tadpoles of the common toad (Rhinella arenarum) treated with the herbicides Liberty® and glufosinate-ammonium.

PubMed

Lajmanovich, Rafael C; Cabagna-Zenklusen, Mariana C; Attademo, Andrés M; Junges, Celina M; Peltzer, Paola M; Bassó, Agustín; Lorenzatti, Eduardo

2014-07-15

The assessment of micronucleated erythrocytes (ME) in blood represents a widely used method for the detection of chromosomal damage by chemical agents, such as herbicides that may occur as water contaminants. We investigated the changes in some circulating blood-cell parameters of tadpoles of the common toad (Rhinella arenarum) that were exposed during 48 or 96 h to three sub-lethal concentrations (3.75, 7.5, and 15 mg/L) of a commercial formulation of a glufosinate-ammonium (GLA)-based herbicide (Liberty(®), LY(®)) as well as to the corresponding active ingredient GLA. The frequency of ME and other erythrocyte nuclear abnormalities (ENA, i.e., lobed nuclei, binucleates or segmented nuclei, kidney-shaped nuclei, notched nuclei, and picnotic nuclei) were evaluated and compared with positive (cyclophosphamide, CP, 40 mg/L) and negative (de-chlorinated tap water) controls. The results indicate that the exposure of R. arenarum tadpoles to LY(®) induces a concentration-dependent increase in ME frequency. The ENA frequency at 48 h was also significantly higher than that in the negative control group for all the chemicals assayed (CP, LY(®) and GLA) whereas at 96 h, increases in ENA over the negative control group were found only for CP and GLA (7.5 mg/L). Our study demonstrates that the commercial formulation of a GLA-based herbicide induces micronucleus formation in R. arenarum tadpoles, in contrast to the active ingredient. According to these results, the inert ingredients of the commercial formulation played an important role in the production of genotoxic damage in erythrocytes of amphibian tadpoles. Copyright © 2014 Elsevier B.V. All rights reserved.

Sensitivity of toad tadpoles, Bufo melanostictus (Schneider), to heavy metals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khangarot, B.S.; Ray, P.K.

1987-03-01

Amphibian larval stages have several qualities which make them as a useful indicator of harmful levels of pollutants in bioassay tests. Amphibian tadpoles show a variety of sublethal responses such as changes in growth, development rates, pigmentation and expression of morphological deformities in a lesser time of exposure to the environmental pollutants. The objective of the work reported in this paper was to determine the acute toxicity of cadmium, copper, chromium, mercury, nickel, silver and zinc to the tadpoles of toad Bufo melanostictus (Schneider), which is commonly available and breed in aquatic habitats exhibiting a wide range of temperature andmore » varying water quality.« less

PATTERN OF CHOLINESTERASE INHIBITION IN ADULT, MALE RATS CHRONICALLY EXPOSED TO DIETARY CHLORPYRIFOS.

EPA Science Inventory

Very little is known about the effects of chronic exposure to relatively low levels of anticholinesterase insecticides or how the effects of chronic exposure compare to higher, intermittent exposure of the same compound for the same duration. To that end, we exposed adult male ra...

Skeletal advance and arrest in giant non-metamorphosing African clawed frog tadpoles (Xenopus laevis: Daudin)

PubMed Central

Kerney, Ryan; Wassersug, Richard; Hall, Brian K

2010-01-01

This study examines the skeletons of giant non-metamorphosing (GNM) Xenopus laevis tadpoles, which arrest their development indefinitely before metamorphosis, and grow to excessively large sizes in the absence of detectable thyroid glands. Cartilage growth is isometric; however, chondrocyte size is smaller in GNM tadpoles than in controls. Most cartilages stain weakly with alcian blue, and several cartilages are calcified (unlike controls). However, cartilages subjacent to periosteum-derived bone retain strong affinities for alcian blue, indicating a role for periosteum-derived bone in the retention of glycosaminoglycans during protracted larval growth. Bone formation in the head, limb, and axial skeletons is advanced in comparison with stage-matched controls, but arrests at various mid-metamorphic states. Both dermal and periosteum-derived bones grow to disproportionately large sizes in comparison to controls. Additionally, mature monocuspid teeth form in several GNM tadpoles. Advances in skeletal development are attributable to the old ages and large sizes of these tadpoles, and reveal unexpected developmental potentials of the pre-metamorphic skeleton. PMID:20402828

The progestin norethisterone affects thyroid hormone-dependent metamorphosis of Xenopus laevis tadpoles at environmentally relevant concentrations.

PubMed

Lorenz, Claudia; Krüger, Angela; Schöning, Viola; Lutz, Ilka

2018-04-15

Previously, levonorgestrel (LNG) has been shown to be an endocrine disruptor of the amphibian thyroid system. In the present study, we investigated whether anti-thyroidal effects are a common property of progestins other than LNG. Premetamorphic Xenopus laevis tadpoles were exposed to norethisterone (NET) and dienogest DIE (each at 0.1-10nM) and LNG (10nM) until completion of metamorphosis. LNG and NET at all concentrations caused a significant developmental retardation whereas DIE did not impair time to metamorphosis. In LNG and 10nM NET exposed animals, tsh mRNA levels increased considerably later than the developmental delay occurred and thyroid histopathology showed no signs of TSH-hyperstimulation. Instead, thyroid glands from these treatments appeared inactive in producing thyroid hormones. Thyroidal transcript levels of dio2 and dio3 were increased by treatments with LNG and NET at 1nM and 10nM, whereas iyd mRNA was reduced by LNG and 10nM NET. Expression of slc5α5 was not changed by any treatment. Effects of DIE differed from those induced by LNG and NET. No developmental delay was measurable; however, tshβ and dio2 mRNAs were increased in pituitary glands of tadpoles exposed to 1.0nM and 10nM DIE. Thyroid histopathology displayed no abnormalities and thyroidal mRNA expression of the genes analyzed (slc5α5, iyd, dio2, dio3) was not changed by DIE. Overall, our results provide evidence that the anti-thyroidal effects already known from LNG are also present in another progestin, namely NET, even at environmentally relevant concentrations. In conclusion we suggest that progestins do not only pose an environmental risk in terms of their impact on reproductive success of aquatic vertebrates, but also with respect to their anti-thyroidal properties affecting amphibian metamorphosis. Copyright © 2017 Elsevier Inc. All rights reserved.

Molecular and sensory mechanisms to mitigate sunlight-induced DNA damage in treefrog tadpoles.

PubMed

Schuch, André P; Lipinski, Victor M; Santos, Mauricio B; Santos, Caroline P; Jardim, Sinara S; Cechin, Sonia Z; Loreto, Elgion L S

2015-10-01

The increased incidence of solar ultraviolet B (UVB) radiation has been proposed as an environmental stressor, which may help to explain the enigmatic decline of amphibian populations worldwide. Despite growing knowledge regarding the UV-induced biological effects in several amphibian models, little is known about the efficacy of DNA repair pathways. In addition, little attention has been given to the interplay between these molecular mechanisms with other physiological strategies that avoid the damage induced by sunlight. Here, DNA lesions induced by environmental doses of solar UVB and UVA radiation were detected in genomic DNA samples of treefrog tadpoles (Hypsiboas pulchellus) and their DNA repair activity was evaluated. These data were complemented by monitoring the induction of apoptosis in blood cells and tadpole survival. Furthermore, the tadpoles' ability to perceive and escape from UV wavelengths was evaluated as an additional strategy of photoprotection. The results show that tadpoles are very sensitive to UVB light, which could be explained by the slow DNA repair rates for both cyclobutane pyrimidine dimers (CPDs) and pyrimidine (6,4) pyrimidone photoproducts (6,4PPs). However, they were resistant to UVA, probably as a result of the activation of photolyases during UVA irradiation. Surprisingly, a sensory mechanism that triggers their escape from UVB and UVA light avoids the generation of DNA damage and helps to maintain the genomic integrity. This work demonstrates the genotoxic impact of both UVB and UVA radiation on tadpoles and emphasizes the importance of the interplay between molecular and sensory mechanisms to minimize the damage caused by sunlight. © 2015. Published by The Company of Biologists Ltd.

Thermal performance curves under daily thermal fluctuation: A study in helmeted water toad tadpoles.

PubMed

Bartheld, José L; Artacho, Paulina; Bacigalupe, Leonardo

2017-12-01

Most research in physiological ecology has focused on the effects of mean changes in temperature under the classic "hot vs cold" acclimation treatment; however, current evidence suggests that an increment in both the mean and variance of temperature could act synergistically to amplify the negative effects of global temperature increase and how it would affect fitness and performance-related traits in ectothermic organisms. We assessed the effects of acclimation to daily variance of temperature on thermal performance curves of swimming speed in helmeted water toad tadpoles (Calyptocephalella gayi). Acclimation treatments were 20°C ± 0.1 SD (constant) and 20°C ± 1.5 SD (fluctuating). We draw two key findings: first, tadpoles exposed to daily temperature fluctuation had reduced maximal performance (Z max ), and flattened thermal performance curves, thus supporting the "vertical shift or faster-slower" hypothesis, and suggesting that overall swimming performance would be lower through an examination of temperatures under more realistic and ecologically-relevant fluctuating regimens; second, there was significant interindividual variation in performance traits by means of significant repeatability estimates. Our present results suggest that the widespread use of constant acclimation temperatures in laboratory experiments to estimate thermal performance curves (TPCs) may lead to an overestimation of actual organismal performance. We encourage the use of temperature fluctuation acclimation treatments to better understand the variability of physiological traits, which predict ecological and evolutionary responses to global change. Copyright © 2017 Elsevier Ltd. All rights reserved.

Soil removal as a decontamination practice and radiocesium accumulation in tadpoles in rice paddies at Fukushima.

PubMed

Sakai, Masaru; Gomi, Takashi; Nunokawa, Masanori; Wakahara, Taeko; Onda, Yuichi

2014-04-01

We investigated the biological accumulation of radiocesium in tadpoles [Rana (Pelophylax) porosa porosa] in rice paddies with and without decontamination practice at Fukushima. Radiocesium was accumulated in surface part of soils both in the control and decontaminated paddies one year after decontamination. Mean (134)Cs and (137)Cs concentrations in tadpoles in the control and decontaminated paddies were 3000 and 4500, and 600 and 890 Bq/kg dry weight, respectively. Radiocesium concentrations in surface soil (0-5 cm depth) and tadpoles in the decontaminated paddy were five times smaller than in the control paddy. These results suggest that decontamination practice can reduce radiocesium concentrations in both soil and tadpoles. However, at the decontaminated paddy, radiocesium concentrations in surface soils became 3.8 times greater one year after decontamination, which indicates that monitoring the subsequent movement of radiocesium in rice paddies and surrounding areas is essential for examining contamination propagation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Heavy metals in bullfrog (Rana catesbeiana) tadpoles: Effects of depuration before analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burger, J.; Snodgrass, J.

1998-11-01

Although tadpoles may well be excellent organisms to use as bioindicators of heavy metal contamination, the relationship of deposition in the body compared to the tail, and the effect of sediments or other debris in the digestive tract on heavy metal concentrations is unknown. The authors examined the effect of experimental depuration of bullfrog (Rana catesbeiana) tadpoles on heavy metal and selenium concentrations in intact tadpoles, as well as their bodies and tails. They defined depuration in this experiment as allowing defecation as an elimination process for intestinal contents. The authors maintained wild-caught tadpoles in clean water for 0, 24,more » 48, and 72 h to determine the effects of clearing on heavy metal concentrations. They also examined the concentrations of heavy metals in the whole body and digestive tract separately. The authors test the null hypotheses that no differences occur in metals as a function of time in uncontaminated water, and that no differences occur in metal concentrations in the body compared to the tail and to the digestive tract. They rejected these hypotheses based on regression models. Variance in concentrations of chromium (77%) and lead (70%) were explained by part and clearing time; for manganese (80%), mercury (64%), selenium (28%), and cadmium (25%) the variation was explained only by body part; for arsenic (53%), the variation was explained by part, clearing time, and weight of the various parts. For those metals in which clearing time explained part of the variation, metal concentrations in both the body and tail decreased after 24 and 48 h, but increased slightly thereafter. Clearing, however, did not greatly decrease metal concentrations in either the body or tail. These data suggest that for some metals (mercury, manganese, cadmium, selenium), clearing has no effect, and for others the effect is slight. For fresh tadpoles, however, the digestive tract contained significantly higher concentrations of all metals

Experimental test of intraspecific competition mechanisms among tadpoles of Leptodactylus ocellatus (Anura: Leptodactylidae).

PubMed

Laufer, Gabriel; Maneyro, Raúl

2008-03-01

Intraspecific competition is predicted to strongly influence species abundance and dynamics through two main mechanisms: consumption and interference of resources. Tadpoles were used in experiments in which we tried to elucidate the relative importance of each mechanism. Our goal was to apply this experimental procedure to Leptodactylus ocellatus, a common South American anuran, a species whose larvae exhibit aggregative behavior and receive parental care. Previous work suggests that tadpole schools should present lower levels of intraspecific competition. Tadpoles from a single nest were reared in the laboratory in three densities (1, 2, and 4 individuals/container) and three food levels (1, 2, and 4 ration multiples) in a randomized three-block design for a factorial analysis of variance, up to day eight. Contrary to previous work with other species, our results show both the absence of interference competition effects, and that larval growth depends only on per capita food availability. The differences between species in intraspecific competition mechanisms are probably related to strong differences in ecology and life history. Leptodactylus ocellatus tadpoles could be directing interference competition away from their kin, reducing schooling costs. Further studies (including kinship as a factor) would give more information about these larvae, allowing a better understanding of the evolutionary and ecological mechanisms behind the biological patterns observed in Leptodactylus species.

Tadpole renormalization and relativistic corrections in lattice NRQCD

NASA Astrophysics Data System (ADS)

Shakespeare, Norman H.; Trottier, Howard D.

1998-08-01

We make a detailed comparison of two tadpole renormalization schemes in the context of the quarkonium hyperfine splittings in lattice NRQCD. We renormalize improved gauge-field and NRQCD actions using the mean-link u0,L in the Landau gauge, and using the fourth root of the average plaquette u0,P. Simulations are done for the three quarkonium systems cc¯, bc¯, and bb¯. The hyperfine splittings are computed both at leading [O(MQv4)] and at next-to-leading [O(MQv6)] order in the relativistic expansion, where MQ is the renormalized quark mass, and v2 is the mean-squared velocity. Results are obtained at a large number of lattice spacings, in the range of about 0.14-0.38 fm. A number of features emerge, all of which favor tadpole renormalization using u0,L. This includes a much better scaling behavior of the hyperfine splittings in the three quarkonium systems when u0,L is used. We also find that relativistic corrections to the spin splittings are smaller when u0,L is used, particularly for the cc¯ and bc¯ systems. We also see signs of a breakdown in the NRQCD expansion when the bare quark mass falls below about 1 in lattice units. Simulations with u0,L also appear to be better behaved in this context: the bare quark masses turn out to be larger when u0,L is used, compared to when u0,P is used on lattices with comparable spacings. These results also demonstrate the need to go beyond tree-level tadpole improvement for precision simulations.

Cryptic infection of a broad taxonomic and geographic diversity of tadpoles by Perkinsea protists.

PubMed

Chambouvet, Aurélie; Gower, David J; Jirků, Miloslav; Yabsley, Michael J; Davis, Andrew K; Leonard, Guy; Maguire, Finlay; Doherty-Bone, Thomas M; Bittencourt-Silva, Gabriela Bueno; Wilkinson, Mark; Richards, Thomas A

2015-08-25

The decline of amphibian populations, particularly frogs, is often cited as an example in support of the claim that Earth is undergoing its sixth mass extinction event. Amphibians seem to be particularly sensitive to emerging diseases (e.g., fungal and viral pathogens), yet the diversity and geographic distribution of infectious agents are only starting to be investigated. Recent work has linked a previously undescribed protist with mass-mortality events in the United States, in which infected frog tadpoles have an abnormally enlarged yellowish liver filled with protist cells of a presumed parasite. Phylogenetic analyses revealed that this infectious agent was affiliated with the Perkinsea: a parasitic group within the alveolates exemplified by Perkinsus sp., a "marine" protist responsible for mass-mortality events in commercial shellfish populations. Using small subunit (SSU) ribosomal DNA (rDNA) sequencing, we developed a targeted PCR protocol for preferentially sampling a clade of the Perkinsea. We tested this protocol on freshwater environmental DNA, revealing a wide diversity of Perkinsea lineages in these environments. Then, we used the same protocol to test for Perkinsea-like lineages in livers of 182 tadpoles from multiple families of frogs. We identified a distinct Perkinsea clade, encompassing a low level of SSU rDNA variation different from the lineage previously associated with tadpole mass-mortality events. Members of this clade were present in 38 tadpoles sampled from 14 distinct genera/phylogroups, from five countries across three continents. These data provide, to our knowledge, the first evidence that Perkinsea-like protists infect tadpoles across a wide taxonomic range of frogs in tropical and temperate environments, including oceanic islands.

Tadpole swimming performance and activity affected by acute exposure to sublethal levels of carbaryl

USGS Publications Warehouse

Bridges, C.M.

1997-01-01

General activity and swimming performance (i.e., sprint speed and distance) of plains leopard frog tadpoles (Rana blairi) were examined after acute exposure to three sublethal concentrations of carbaryl (3.5, 5.0, and 7.2 mg/L). Both swimming performance and spontaneous swimming activity are important for carrying out life history functions (e.g., growth and development) and for escaping from predators. Measured tadpole activity diminished by nearly 90% at 3.5 mg/L carbaryl and completely ceased at 7.2 mg/L. Sprint speed and sprint distance also decreased significantly following exposure. Carbaryl affected both swimming performance and activity after just 24 h, suggesting that 24 h may be an adequate length of exposure to determine behavioral effects on tadpoles. Slight recovery of activity levels was noted at 24 and 48 h post-exposure; no recovery of swimming performance was observed. Reduction in activity and swimming performance may result in increased predation rates and, because activity is closely associated with feeding, may result in slowed growth leading to a failure to emerge before pond drying or an indirect reduction in adult fitness. Acute exposure to sublethal toxicants such as carbaryl may not only affect immediate survival of tadpoles but also impact critical life history functions and generate changes at the local population level.

Notochord-derived hedgehog is essential for tail regeneration in Xenopus tadpole.

PubMed

Taniguchi, Yuka; Watanabe, Kenji; Mochii, Makoto

2014-06-18

Appendage regeneration in amphibians is regulated by the combinatorial actions of signaling molecules. The requirement of molecules secreted from specific tissues is reflected by the observation that the whole process of regeneration can be inhibited if a certain tissue is removed from the amputated stump. Interestingly, urodeles and anurans show different tissue dependencies during tail regeneration. The spinal cord is essential for tail regeneration in urodele but not in anuran larva, whereas the notochord but not the spinal cord is essential for tail regeneration in anuran tadpoles. Sonic hedgehog is one of the signaling molecules responsible for such phenomenon in axolotl, as hedgehog signaling is essential for overall tail regeneration and sonic hedgehog is exclusively expressed in the spinal cord. In order to know whether hedgehog signaling is involved in the molecular mechanism underlying the inconsistent tissue dependency for tail regeneration between anurans and urodeles, we investigated expression of hedgehog signal-related genes in the regenerating tail of Xenopus tadpole and examined the effect of the hedgehog signal inhibitor, cyclopamine, on the tail regeneration. In Xenopus, sonic hedgehog is expressed exclusively in the notochord but not in the spinal cord of the regenerate. Overall regeneration was severely impaired in cyclopamine-treated tadpoles. Notochord maturation in the regenerate, including cell alignment and vacuolation, and myofiber formation were inhibited. Proliferation of spinal cord cells in the neural ampulla and of mesenchymal cells was also impaired. As in the axolotl, hedgehog signaling is required for multiple steps in tail regeneration in the Xenopus tadpole, although the location of the Shh source is quite different between the two species. This difference in Shh localization is the likely basis for the differing tissue requirement for tail regeneration between urodeles and anurans.

Notochord-derived hedgehog is essential for tail regeneration in Xenopus tadpole

PubMed Central

2014-01-01

Background Appendage regeneration in amphibians is regulated by the combinatorial actions of signaling molecules. The requirement of molecules secreted from specific tissues is reflected by the observation that the whole process of regeneration can be inhibited if a certain tissue is removed from the amputated stump. Interestingly, urodeles and anurans show different tissue dependencies during tail regeneration. The spinal cord is essential for tail regeneration in urodele but not in anuran larva, whereas the notochord but not the spinal cord is essential for tail regeneration in anuran tadpoles. Sonic hedgehog is one of the signaling molecules responsible for such phenomenon in axolotl, as hedgehog signaling is essential for overall tail regeneration and sonic hedgehog is exclusively expressed in the spinal cord. In order to know whether hedgehog signaling is involved in the molecular mechanism underlying the inconsistent tissue dependency for tail regeneration between anurans and urodeles, we investigated expression of hedgehog signal-related genes in the regenerating tail of Xenopus tadpole and examined the effect of the hedgehog signal inhibitor, cyclopamine, on the tail regeneration. Results In Xenopus, sonic hedgehog is expressed exclusively in the notochord but not in the spinal cord of the regenerate. Overall regeneration was severely impaired in cyclopamine-treated tadpoles. Notochord maturation in the regenerate, including cell alignment and vacuolation, and myofiber formation were inhibited. Proliferation of spinal cord cells in the neural ampulla and of mesenchymal cells was also impaired. Conclusion As in the axolotl, hedgehog signaling is required for multiple steps in tail regeneration in the Xenopus tadpole, although the location of the Shh source is quite different between the two species. This difference in Shh localization is the likely basis for the differing tissue requirement for tail regeneration between urodeles and anurans. PMID:24941877

Altered gravity affects ventral root activity during fictive swimming and the static vestibuloocular reflex in young tadpoles (Xenopus laevis).

PubMed

Böser, S; Dournon, C; Gualandris-Parisot, L; Horn, E

2008-03-01

During early periods of life, modifications of the gravitational environment affect the development of sensory, neuronal and motor systems. The vestibular system exerts significant effects on motor networks that control eye and body posture as well as swimming. The objective of the present study was to study whether altered gravity (AG) affects vestibuloocular and spinal motor systems in a correlated manner. During the French Soyuz taxi flight Andromède to the International Space Station ISS (launch: October 21, 2001; landing: October 31, 2001) Xenopus laevis embryos were exposed for 10 days to microgravity (microg). In addition, a similar experiment with 3g-hypergravity (3g) was performed in the laboratory. At onset of AG, embryos had reached developmental stages 24 to 27. After exposure to AG, each tadpole was tested for its roll-induced vestibuloocular reflex (rVOR) and 3 hours later it was tested for the neuronal activity recorded from the ventral roots (VR) during fictive swimming. During the post-AG recording periods tadpoles had reached developmental stages 45 to 47. It was observed that microgravity affected VR activity during fictive swimming and rVOR. In particular, VR activity changes included a significant decrease of the rostrocaudal delay and a significant increase of episode duration. The rVOR-amplitude was transiently depressed. Hypergravity was less effective on the locomotor pattern; occurring effects on fictive swimming were the opposite of microg effects. As after microgravity, the rVOR was depressed after 3g-exposure. All modifications of the rVOR and VR-activity recovered to normal levels within 4 to 7 days after termination of AG. Significant correlations between the rVOR amplitude and VR activity of respective tadpoles during the recording period have been observed in both tadpoles with or without AG experience. The data are consistent with the assumptions that during this period of life which is characterized by a progressive development

[Trophic ecology in tadpoles of Rhinella arenarum (Anura: Bufonidae) in agroecosystems and their possible implications for conservation].

PubMed

Bionda, Clarisa; Gari, Noemi; Luque, Elisa; Salas, Nancy; Lajmanovich, Rafael; Martino, Adolfo

2012-06-01

The progress of the agriculture border has led an important loss of natural habitats, with significant consequences for biodiversity. In this sense, the studies in anuran amphibian tadpoles inhabiting these environments are relevant, because the larval stage is a phase of population regulation. The aim of this study was to analyze the body condition and diet in Rhinella arenarum, tadpoles, an anuran species widely distributed in South America and that inhabit agroecosystems. Three sites were sampled, two agroecosystems with different alteration degrees (C1 and C2) and an uncultured (SM) third place. The captured tadpoles were anesthetized, fixed and preserved in formaldehyde (10%). Subsequently, body measurements were made and the complete intestine was removed and analyzed for food items under a binocular microscope. The diet in R. arenarum tadpoles has a dominance of algae Bacillariophyceae, followed by Cyanophyceae. In particular, the class Bacillariophyceae, due to the presence of the genus Navicula, Nitzschia, Gomphonema and Hantzschia, was important in the diet of the anurans in those agroecosystems. Class Cyanophyceae, mainly represented by genus Oscillatoria and Euglenophyceae represented by Euglena and Strombomonas, were predominant in the diet of the anurans in SM. Some differences in the total items consumed by tadpole were observed between the studied sites. Tadpoles that inhabit the modified sites (C1 and C2) recorded a significantly smaller amount of food. Moreover, the tadpoles that inhabit these sites showed a lower body condition. The presence of certain algae associated with eutrophic environments, could indicate some pollution in agroecosystems (C1 and C2). Food resources would be lesser in places with strong agricultural activity, possibly with a greater degree of eutrophication. A smaller food amount could have consequences at population level for the short and long time terms, because of its impact on individual growth. Larval diet is

Ontogenetic loss of phenotypic plasticity of age at metamorphosis in tadpoles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hensley, F.R.

1993-12-01

Amphibian larvae exhibit phenotypic plasticity in size at metamorphosis and duration of the larval period. I used Pseudacris crucifer tadpoles to test two models for predicting tadpole age and size at metamorphosis under changing environmental conditions. The Wilbur-Collins model states that metamorphosis is initiated as a function of a tadpole's size and relative growth rate, and predicts that changes in growth rate throughout the larval period affect age and size at metamorphosis. An alternative model, the fixed-rate model, states that age at metamorphosis is fixed early in larval life, and subsequent changes in growth rate will have no effect onmore » the length of the larval period. My results confirm that food supplies affect both age and size at metamorphosis, but developmental rates became fixed at approximately Gosner (1960) stages 35-37. Neither model completely predicted these results. I suggest that the generally accepted Wilbur-Collins model is improved by incorporating a point of fixed developmental timing. Growth trajectories predicted from this modified model fit the results of this study better than trajectories based on either of the original models. The results of this study suggests a constraint that limits the simultaneous optimization of age and size at metamorphosis. 32 refs., 5 figs., 1 tab.« less

Hepatic effects of the clomazone herbicide in both its free form and associated with chitosan-alginate nanoparticles in bullfrog tadpoles.

PubMed

de Oliveira, Cristiane Ronchi; Fraceto, Leonardo Fernandes; Rizzi, Gisele Miglioranza; Salla, Raquel Fernanda; Abdalla, Fábio Camargo; Costa, Monica Jones; Silva-Zacarin, Elaine Cristina Mathias

2016-04-01

The use of agrochemicals in agriculture is intense and most of them could be carried out to aquatic environment. Nevertheless, there are only few studies that assess the effects of these xenobiotics on amphibians. Clomazone is an herbicide widely used in rice fields, where amphibian species live. Thus, those species may be threatened by non-target exposure. However, nanoparticles are being developed to be used as a carrier system for the agrochemicals. Such nanoparticles release the herbicide in a modified way, and are considered to be more efficient and less harmful to the environment. The aim of this study was to comparatively evaluate the effect of clomazone in its free form and associated with nanoparticles, in the liver of bullfrog tadpoles (Lithobates catesbeianus) when submitted to acute exposure for 96 h. According to semi-quantitative analysis, there was an increase in the frequency of melanomacrophage centres, in the accumulation of eosinophils and in lipidosis in the liver of experimental groups exposed to clomazone - in its free form and associated with nanoparticles - in comparison with the control group, and the nanotoxicity of chitosan-alginate nanoparticles. The increase of melanomacrophage centres in all exposed groups was significant (P < 0.0001) in comparison to control group. Therefore, the results of this research have shown that exposure to sublethal doses of the herbicide and nanoparticles triggered hepatic responses. Moreover, these results provided important data about the effect of the clomazone herbicide and organic nanoparticles, which act as carriers of agrochemicals, on the bullfrog tadpole liver. Copyright © 2016 Elsevier Ltd. All rights reserved.

Cool tadpoles from Arctic environments waste fewer nutrients - high gross growth efficiencies lead to low consumer-mediated nutrient recycling in the North.

PubMed

Liess, Antonia; Guo, Junwen; Lind, Martin I; Rowe, Owen

2015-11-01

Endothermic organisms can adapt to short growing seasons, low temperatures and nutrient limitation by developing high growth rates and high gross growth efficiencies (GGEs). Animals with high GGEs are better at assimilating limiting nutrients and thus should recycle (or lose) fewer nutrients. Longer guts in relation to body mass may facilitate higher GGE under resource limitation. Within the context of ecological stoichiometry theory, this study combines ecology with evolution by relating latitudinal life-history adaptations in GGE, mediated by gut length, to its ecosystem consequences, such as consumer-mediated nutrient recycling. In common garden experiments, we raised Rana temporaria tadpoles from two regions (Arctic/Boreal) under two temperature regimes (18/23 °C) crossed with two food quality treatments (high/low-nitrogen content). We measured tadpole GGEs, total nutrient loss (excretion + egestion) rates and gut length during ontogeny. In order to maintain their elemental balance, tadpoles fed low-nitrogen (N) food had lower N excretion rates and higher total phosphorous (P) loss rates than tadpoles fed high-quality food. In accordance with expectations, Arctic tadpoles had higher GGEs and lower N loss rates than their low-latitude conspecifics, especially when fed low-N food, but only in ambient temperature treatments. Arctic tadpoles also had relatively longer guts than Boreal tadpoles during early development. That temperature and food quality interacted with tadpole region of origin in affecting tadpole GGEs, nutrient loss rates and relative gut length, suggests evolved adaptation to temperature and resource differences. With future climate change, mean annual temperatures will increase. Additionally, species and genotypes will migrate north. This will change the functioning of Boreal and Arctic ecosystems by affecting consumer-mediated nutrient recycling and thus affect nutrient dynamics in general. Our study shows that evolved latitudinal adaption can

Enhanced Iron Uptake of Saccharomyces cerevisiae by Heterologous Expression of a Tadpole Ferritin Gene

PubMed Central

Shin, Young-Mi; Kwon, Tae-Ho; Kim, Kyung-Suk; Chae, Keon-Sang; Kim, Dae-Hyuk; Kim, Jae-Ho; Yang, Moon-Sik

2001-01-01

We genetically engineered Saccharomyces cerevisiae to express ferritin, a ubiquitous iron storage protein, with the major heavy-chain subunit of tadpole ferritin. A 450-kDa ferritin complex can store up to 4,500 iron atoms in its central cavity. We cloned the tadpole ferritin heavy-chain gene (TFH) into the yeast shuttle vector YEp352 under the control of a hybrid alcohol dehydrogenase II and glyceraldehyde-3-phosphate dehydrogenase promoter. We confirmed transformation and expression by Northern blot analysis of the recombinant yeast, by Western blot analysis using an antibody against Escherichia coli-expressed TFH, and with Prussian blue staining that indicated that the yeast-expressed tadpole ferritin was assembled into a complex that could bind iron. The recombinant yeast was more iron tolerant in that 95% of transformed cells, but none of the recipient strain cells, could form colonies on plates containing 30 mM ferric citrate. The cell-associated concentration of iron was 500 μg per gram (dry cell weight) of the recombinant yeast but was 210 μg per gram (dry cell weight) in the wild type. These findings indicate that the iron-carrying capacity of yeast is improved by heterologous expression of tadpole ferritin and suggests that this approach may help relieve dietary iron deficiencies in domesticated animals by the use of the engineered yeast as a feed and food supplement. PMID:11229922

THE INFLUENCE OF THE SIMULTANEOUS EFFECT OF X-RAY IRRADIATION AND SOME NARCOTICS AND STIMULANTS ON THE MORTALITY OF TADPOLES (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Praslicka, M.; Helona, J.; Havelka, J.

1955-01-01

Tadpoles of Rana esculenta were selected for experiments to ascertain changes in the action of irradiation produced by certain narcotics and by strychnine. The control tadpoles were irradiated with a dose of 27,500 r, as were also tadpoles in a watery solution of one of the following substances: ether (0.1%), ethanol (2 and 2.5%), chloral hydrate (0.3%), avertine (irradiation in water for 5 mins. in 0.1% solution), strychnine (1: 100,000, of the tadpoles irradiated in the watery solution of narcotic substances is in all cases statistically and significantly prolonged in comparison with that in the case of the tadpoles irradiatedmore » in water. Strychnine in a concentration of 1: 100,000, which produced signs of irritation, produced sensitivity to irradiation; in concentrations of 1: 50,000 and 1: 30,000, which produced inhibition, it had a protective effect, in as far as the tadpoles survived the toxic action of the strychnine. It would appear that irradiation intensifies the toxic action of avertine, ether, chloroform, and scopolamine. (auth)« less

Health status of tadpoles and metamorphs of Rhinella arenarum (Anura, Bufonidae) that inhabit agroecosystems and its implications for land use.

PubMed

Babini, María Selene; Bionda, Clarisa de Lourdes; Salas, Nancy Edith; Martino, Adolfo Ludovico

2015-08-01

Perturbations of water bodies near agricultural and livestock systems can affect embryonic and larval stages of anurans and negatively impact adult populations and structure of amphibian communities. This study is focused on early development of Rhinella arenarum, for which body growth, abnormalities in the oral disc and genetic damage on erythrocytes were analyzed to establish the impact of agroecosystems on local populations of amphibians. Tadpoles and metamorphs of R. arenarum were collected in three agroecosystems (namely, C1, C2, and C3) and in a site without agricultural and livestock activities (SM) from central Argentina. Egg masses of C1 were extracted for breeding tadpoles under laboratory conditions (Lab). Tadpoles were in small size and lighter in weight in C1 and C2. Metamorphs were shorter and lighter in weight in C1 and C3. In SM and Lab samples, no tadpoles with abnormal LTRF (labial tooth row formula) or without labial teeth were observed. In C1, the highest frequency of abnormal LTRF was recorded and was the only site in which tadpoles without labial teeth were found. In C1 and C2 the tadpoles had highest micronucleus frequencies and nuclear abnormalities. C1 can be considered as the site with the highest anthropogenic perturbation and with less healthy tadpoles. Livestock practices such as alternating cattle between parcel and keeping a buffer between crops and water bodies, would allow a better development of the first aquatic stages that are essential for the conservation of the anuran populations. Copyright © 2015 Elsevier Inc. All rights reserved.

Naturally occurring variation in tadpole morphology and performance linked to predator regime

PubMed Central

Johnson, James B; Saenz, Daniel; Adams, Cory K; Hibbitts, Toby J

2015-01-01

Divergent natural selection drives a considerable amount of the phenotypic and genetic variation observed in natural populations. For example, variation in the predator community can generate conflicting selection on behavioral, life-history, morphological, and performance traits. Differences in predator regime can subsequently increase phenotypic and genetic variations in the population and result in the evolution of reproductive barriers (ecological speciation) or phenotypic plasticity. We evaluated morphology and swimming performance in field collected Bronze Frog larvae (Lithobates clamitans) in ponds dominated by predatory fish and those dominated by invertebrate predators. Based on previous experimental findings, we hypothesized that tadpoles from fish-dominated ponds would have small bodies, long tails, and large tail muscles and that these features would facilitate fast-start speed. We also expected to see increased tail fin depth (i.e., the tail-lure morphology) in tadpoles from invertebrate-dominated ponds. Our results support our expectations with respect to morphology in affecting swimming performance of tadpoles in fish-dominated ponds. Furthermore, it is likely that divergent natural selection is playing a role in the diversification on morphology and locomotor performance in this system. PMID:26357533

Divergent patterns of abundance and age-class structure of headwater stream tadpoles in burned and unburned watersheds

USGS Publications Warehouse

Hossack, B.R.; Corn, P.S.; Fagre, D.B.

2006-01-01

Wildfire is a potential threat to many species with narrow environmental tolerances like the Rocky Mountain tailed frog (Ascaphus montanus Mittleman and Myers, 1949), which inhabits a region where the frequency and intensity of wildfires are expected to increase. We compared pre- and post-fire counts of tadpoles in eight streams in northwestern Montana to determine the effects of wildfire on A. montanus. All streams were initially sampled in 2001, 2 years before four of them burned in a large wildfire, and were resampled during the 2 years following the fire. Counts of tadpoles were similar in the two groups of streams before the fire. After the fire, tadpoles were almost twice as abundant in unburned streams than in burned streams. The fire seemed to have the greatest negative effect on abundance of age-1 tadpoles, which was reflected in the greater variation in same-stream age-class structure compared with those in unburned streams. Despite the apparent effect on tadpoles, we do not expect the wildfire to be an extirpation threat to populations in the streams that we sampled. Studies spanning a chronosequence of fires, as well as in other areas, are needed to assess the effects of fires on streams with A. montanus and to determine the severity and persistence of these effects.

Negative impact of a cadmium concentration considered environmentally safe in Brazil on the cardiac performance of bullfrog tadpoles.

PubMed

Dal-Medico, S E; Rissoli, R Z; Gamero, F U; Victório, J A; Salla, R F; Abdalla, F C; Silva-Zacarin, E C M; Carvalho, C S; Costa, M J

2014-06-01

A drastic amphibian decline has been observed worldwide, which can be attributed (among other factors) to exposure to pollutants. Considering that cadmium corresponds to the most rapidly increasing trace metal in the environment, the aim of this work was to evaluate whether the exposure (2 and 16 days) of bullfrog tadpoles to this trace metal, at the concentration currently considered environmentally safe (at 1ppb) in class 1 and 2 waters by the Brazilian Environmental Council, can affect the cardiac performance of these animals. The acute exposure (2 days) of tadpoles to cadmium resulted in a marked bradycardic response, which was correlated with an incomplete cardiac relaxation, without any compensation by improved cardiac twitch force (Fc) or contraction velocity (TPT), nor even by cardiac hypertrophy. Indeed, after 16 days of exposure, the cardiac function of tadpoles became even more depressed due to a marked decrease in Fc, a prolongation of TPT, and also incomplete relaxation (i.e. increases in the ventricle resting tension), without changes in ventricle relative mass. Altogether, the cardiodepressive effects of cadmium (especially after more prolonged exposure periods) impose negative alterations on a tadpole׳s development and also impede adequate homeostatic adjustments to respond appropriately to the exposure to cadmium with increase in energetic demand to counteract the deleterious effects of the xenobiotic. These disturbances can impair tadpoles׳ growth, development and reproduction. It is a fact that allows us to strongly suggest that cadmium concentrations, which are currently considered environmentally safe in Brazil, should be revised. Copyright © 2014 Elsevier Inc. All rights reserved.

Heart rate variability in workers chronically exposed to lead.

PubMed

Gajek, Jacek; Zyśko, Dorota; Chlebda, Ewa

2004-07-01

Lead is a strong neurotoxin. The effects of lead on the activity of the autonomic nervous system, assessed by the use of heart rate variability (HRV) analysis, have not yet been established. To assess the effects of occupational chronic lead exposure on the autonomic nervous system activity. The study group consisted of 22 copper foundry workers (mean age 41.8+/-8.7 years) who had elevated parameters of lead overload and were admitted to the hospital for chelate therapy. The control group consisted of 13 age-matched healthy males. Lead concentration was measured with the use of atomic absorption spectrophotometry, and concentration of free protoporphyrins in erythrocytes (FEP) using a fluorometric method. Each patient underwent 24-hour ambulatory ECG monitoring, and standard short-term as well as long-term HRV parameters were obtained. There were no significant differences between patients and controls in HRV parameters. In the control group, HRV parameters correlated with age. In patients, a significant negative correlation between lead concentration and some short-term HRV parameters calculated during the night was found: SDNN (r=-0.48, p<0.05), TP (r=-0.48, p<0.01) and LF (r=-0.48, p<0.01). In patients, a negative correlation between lead concentration and HFnight/HFday index was found (r=-0.47 p<0.01), whereas in controls this correlation was positive (r=0.66 p<0.05). Overall HRV indices are similar in subjects exposed to lead and in healthy controls. A decrease in the physiological elevation of HF values during the night, together with an increase in lead blood concentration and lack of relationship between age and HRV parameters in workers chronically exposed to lead may suggest disturbances of the autonomic system. In subjects not exposed to lead a decrease in heart rate with an increase in FEP concentration was observed.

Testing the relationship between human occupancy in the landscape and tadpole developmental stress.

PubMed

Eterovick, Paula C; Bar, Luís F F; Souza, Jorge B; Castro, José F M; Leite, Felipe S F; Alford, Ross A

2015-01-01

Amphibian population declines are widespread; the main causal factors are human related and include habitat fragmentation due to agriculture, mining, fires, and urban development. Brazil is the richest country in species of amphibians, and the Brazilian regions with the greatest amphibian diversity are experiencing relatively high rates of habitat destruction, but there are presently relatively few reports of amphibian declines. It is thus important to develop research methods that will detect deterioration in population health before severe declines occur. We tested the use of measurements of fluctuating asymmetry (FA) taken on amphibian larvae to detect anthropogenic stress. We hypothesized that greater human occupancy in the landscape might result in more stressful conditions for amphibians. We conducted this study at the Espinhaço mountain range in southeastern Brazil, using as a model an endemic species (Bokermannohyla saxicola, Hylidae). We chose two tadpole denticle rows and eye-nostril distance as traits for FA measurement. We measured percent cover of human-altered habitats in the landscape around tadpole sampling points and measured FA levels in sampled tadpoles. We found FA levels to differ among localities but found no relationship between human modification of the landscape and tadpole FA levels. Levels of FA in the traits we examined may not be strongly affected by environmental conditions, or may be affected by local variables that were not captured by our landscape-scale measures. Alternatively, populations may be genetically differentiated, affecting how FA levels respond to stress and obscuring the effects of anthropogenic disturbance.

Testing the Relationship between Human Occupancy in the Landscape and Tadpole Developmental Stress

PubMed Central

Eterovick, Paula C.; Bar, Luís F. F.; Souza, Jorge B.; Castro, José F. M.; Leite, Felipe S. F.; Alford, Ross A.

2015-01-01

Amphibian population declines are widespread; the main causal factors are human related and include habitat fragmentation due to agriculture, mining, fires, and urban development. Brazil is the richest country in species of amphibians, and the Brazilian regions with the greatest amphibian diversity are experiencing relatively high rates of habitat destruction, but there are presently relatively few reports of amphibian declines. It is thus important to develop research methods that will detect deterioration in population health before severe declines occur. We tested the use of measurements of fluctuating asymmetry (FA) taken on amphibian larvae to detect anthropogenic stress. We hypothesized that greater human occupancy in the landscape might result in more stressful conditions for amphibians. We conducted this study at the Espinhaço mountain range in southeastern Brazil, using as a model an endemic species (Bokermannohyla saxicola, Hylidae). We chose two tadpole denticle rows and eye-nostril distance as traits for FA measurement. We measured percent cover of human-altered habitats in the landscape around tadpole sampling points and measured FA levels in sampled tadpoles. We found FA levels to differ among localities but found no relationship between human modification of the landscape and tadpole FA levels. Levels of FA in the traits we examined may not be strongly affected by environmental conditions, or may be affected by local variables that were not captured by our landscape-scale measures. Alternatively, populations may be genetically differentiated, affecting how FA levels respond to stress and obscuring the effects of anthropogenic disturbance. PMID:25793699

Low temperature tolerance, cold hardening and acclimation in tadpoles of the neotropical túngara frog (Engystomops pustulosus).

PubMed

Vo, Pacific; Gridi-Papp, Marcos

2017-05-01

Many frogs from temperate climates can tolerate low temperatures and increase their thermal tolerance through hardening and acclimation. Most tropical frogs, on the other hand, fail to acclimate to low temperatures. This lack of acclimation ability is potentially due to lack of selection pressure for acclimation because cold weather is less common in the tropics. We tested the generality of this pattern by characterizing the critical temperature minimum (CTMin), hardening, and acclimation responses of túngara frogs (Engystomops pustulosus). These frogs belong to a family with unknown thermal ecology. They are found in a tropical habitat with a highly constant temperature regime. The CTMin of the tadpoles was on average 12.5°C. Pre-metamorphic tadpoles hardened by 1.18°C, while metamorphic tadpoles hardened by 0.36°C. When raised at 21°C, tadpoles acclimated expanding their cold tolerance by 1.3°C in relation to larvae raised at 28°C. These results indicate that the túngara frog has a greatly reduced cold tolerance when compared to species from temperate climates, but it responds to cold temperatures with hardening and acclimation comparable to those of temperate-zone species. Cold tolerance increased with body length but cold hardening was more extensive in pre-metamorphic tadpoles than in metamorphic ones. This study shows that lack of acclimation ability is not general to the physiology of tropical anurans. Copyright © 2017 Elsevier Ltd. All rights reserved.

Water velocity tolerance in tadpoles of the foothill yellow-legged frog (Rana boylii): Swimming performance, growth, and survival

Treesearch

S. Kupferberg; A. Lind; V. Thill; S. Yarnell

2011-01-01

We explored the effects of large magnitude flow fluctuations in rivers with dams, commonly referred to as pulsed flows, on tadpoles of the lotic-breeding Foothill Yellow-legged Frog, Rana boylii. We quantified the velocity conditions in habitats occupied by tadpoles and then conducted experiments to assess the tolerance to values at the upper limit...

Biospectroscopy reveals the effect of varying water quality on tadpole tissues of the common frog (Rana temporaria).

PubMed

Strong, Rebecca J; Halsall, Crispin J; Ferenčík, Martin; Jones, Kevin C; Shore, Richard F; Martin, Francis L

2016-06-01

Amphibians are undergoing large population declines in many regions around the world. As environmental pollution from both agricultural and urban sources has been implicated in such declines, there is a need for a biomonitoring approach to study potential impacts on this vulnerable class of organism. This study assessed the use of infrared (IR) spectroscopy as a tool to detect changes in several tissues (liver, muscle, kidney, heart and skin) of late-stage common frog (Rana temporaria) tadpoles collected from ponds with differing water quality. Small differences in spectral signatures were revealed between a rural agricultural pond and an urban pond receiving wastewater and landfill run-off; these were limited to the liver and heart, although large differences in body size were apparent, surprisingly with tadpoles from the urban site larger than those from the rural site. Large differences in liver spectra were found between tadpoles from the pesticide and nutrient impacted pond compared to the rural agricultural pond, particularly in regions associated with lipids. Liver mass and hepatosomatic indices were found to be significantly increased in tadpoles from the site impacted by pesticides and trace organic chemicals, suggestive of exposure to environmental contamination. Significant alterations were also found in muscle tissue between tadpoles from these two ponds in regions associated with glycogen, potentially indicative of a stress response. This study highlights the use of IR spectroscopy, a low-cost, rapid and reagent-free technique in the biomonitoring of a class of organisms susceptible to environmental degradation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of chemical management for invasive plants on the performance of Lithobates pipiens tadpoles.

PubMed

Curtis, Amanda N; Bidart, M Gabriela

2017-11-01

Invasive plants impact amphibians by altering habitat, altering species interactions, and releasing potentially toxic secondary chemicals. Despite being costly and having the potential to affect nontarget wildlife, chemical management is commonly used to control invasive plants. Prior research has indicated that individual effects of invasive plants or herbicides can be harmful to aquatic organisms; however, information is lacking on the combined effect of these factors on amphibians. A laboratory experiment was performed to assess the impact of leachates of the invasive plants Eurasian watermilfoil (Myriophyllum spicatum) and European buckthorn (Rhamnus cathartica), the herbicide Renovate ® 3 (triclopyr [3, 5, 6-trichloro-2-pyridinyloxyacetic acid]), and the combined effects of each plant leachate and the herbicide on the growth, morphology, and survival of northern leopard frog (Lithobates pipiens) tadpoles. No effects of treatment on survival were observed. Tadpole exposure to M. spicatum reduced body mass by 17%, exposure to R. cathartica increased body mass by 36%, and exposure to R. cathartica + low herbicide increased body mass by 38% (although only early in the experiment). Exposure to Renovate 3 induced a 16% and 29% decrease in tadpole size in lower (0.22 mg triclopyr active ingredient [a.i.]/L) and higher (0.92 mg triclopyr a.i./L) concentration treatments, respectively. Results from the present study highlight the importance of considering both individual and combined effects of invasive plants and herbicides because they may have different outcomes for tadpole growth and development. Environ Toxicol Chem 2017;36:2958-2964. © 2017 SETAC. © 2017 SETAC.

Atrial arrhythmias and autonomic dysfunction in rats exposed to chronic intermittent hypoxia.

PubMed

Bober, Sara L; Ciriello, John; Jones, Douglas L

2018-06-01

Obstructive sleep apnea, which involves chronic intermittent hypoxia (CIH), is a major risk factor for developing atrial fibrillation (AF). Whether or not CIH alone alters cardiac mechanisms to support AF is unknown. This study investigated the effects of CIH on atrial electrophysiology and arrhythmia vulnerability and evaluated the role of autonomics in CIH promotion of AF. Adult male Sprague-Dawley rats were exposed to 8 h/day of CIH or normoxia for 7 days. After exposure, rats were anesthetized for intracardiac electrophysiological experiments. Atrial effective refractory periods (AERPs) and AF inducibility were determined using programmed electrical stimulation and burst pacing in the absence and presence of autonomic receptor agonists and antagonists. Western blot analysis measured atrial protein expression of muscarinic M2, M3, and β 1 -adrenergic receptors. Compared with normoxia-exposed control rats, CIH-exposed rats had enhanced AF vulnerability using both programmed electrical stimulation and burst pacing, accompanied by greater AERP responses to carbachol and propranolol, lesser responses to isoproterenol, and higher atrial M2 receptor protein levels. Enhanced atrial vulnerability was accentuated by carbachol and abolished by atropine, indicating that the AF-promoting effects of CIH depended principally on parasympathetic activation. Enhancement of atrial vulnerability and AERP shortening with cholinergic agonists in CIH-exposed rats is consistent with sensitivity to parasympathetic activation. Higher responses to adrenergic receptor blockade in CIH-exposed rats is consistent with sympathetic potentiation. These findings implicate CIH as an important mediator of enhanced AF susceptibility in obstructive sleep apnea and provide novel insights into the underlying mechanisms. NEW & NOTEWORTHY Our study demonstrates, for the first time, that chronic intermittent hypoxia alone enhances vulnerability to atrial arrhythmia induction, which depends principally

The effects of acute pesticide exposure on neuroblastoma cells chronically exposed to diazinon.

PubMed

Axelrad, J C; Howard, C V; McLean, W G

2003-03-14

Speculation about potential neurotoxicity due to chronic exposure to low doses of organophosphate (OP) pesticides is not yet supported by experimental evidence. The objective of this work was to use a cell culture model of chronic OP exposure to determine if such exposure can alter the sensitivity of nerve cells to subsequent acute exposure to OPs or other compounds. NB2a neuroblastoma cells were grown in the presence of 25 microM diazinon for 8 weeks. The OP was then withdrawn and the cells were induced to differentiate in the presence of various other pesticides or herbicides, including OPs and OP-containing formulations. The resulting outgrowth of neurite-like structures was measured by light microscopy and quantitative image analysis and the IC(50) for each OP or formulation was calculated. The IC(50) values in diazinon-pre-exposed cells were compared with the equivalent values in cells not pre-exposed to diazinon. The IC(50) for inhibition of neurite outgrowth by acute application of diazinon, pyrethrum, glyphosate or a commercial formulation of glyphosate was decreased by between 20 and 90% after pre-treatment with diazinon. In contrast, the IC(50) for pirimiphos methyl was unaffected and those for phosmet or chlorpyrifos were increased by between 1.5- and 3-fold. Treatment of cells with chlorpyrifos or with a second glyphosate-containing formulation led to the formation of abnormal neurite-like structures in diazinon-pre-exposed cells. The data support the view that chronic exposure to an OP may reduce the threshold for toxicity of some, but by no means all, environmental agents.

Inhalation of progesterone inhibits chronic airway inflammation of mice exposed to ozone.

PubMed

Fei, Xia; Bao, Wuping; Zhang, Pengyu; Zhang, Xue; Zhang, Guoqing; Zhang, Yingying; Zhou, Xin; Zhang, Min

2017-05-01

Chronic ozone exposure leads to a model of mice with lung inflammation, emphysema and oxidative stress. Progesterone plays an important role in attenuating the neuroinflammation. We assume that progesterone will reduce the chronic airway inflammation exposed to ozone and evaluate whether combination of progesterone with glucocorticoids results in synergistic effects. C57/BL6 mice were exposed to ozone (2.5ppm, 3h) 12 times over 6 weeks, and were administered with progesterone (0.03 or 0.3mg/L; inhaled) alone or combined with budesonide (BUD) (0.2g/L) after each exposure until the tenth week. Mice were studied 24h after final exposure, cells and inflammatory mediators were assessed in bronchoalveolar lavage fluid (BALF) and lungs used for evaluation of glucocorticoids receptors (GR), p38 mitogen-activated protein kinase (MAPK) phosphorylation and nuclear transcription factor κB (NF-κB) activation. Exposure to ozone resulted in a marked lung neutrophilia. Moreover, in ozone-exposed group, the levels of oxidative stress-related interleukin (IL)-1β, IL-6, IL-8, IL-17A, activated NF-κB and p38MAPK, airway inflammatory cells infiltration density, mean linear intercept (Lm) were greatly increased, FEV 25 and glucocorticoids receptors (GR) were markedly decreased. Comparable to BUD, progesterone treatment dose-dependently led to a significant reduction of IL-1β, IL-6, IL-8, IL-17A, activated NF-κB and p38MAPK, and an increase of FEV 25 and GR. Progesterone combined with BUD resulted in dramatic changes, compared to monotherapy of BUD or progesterone. Therefore, these results demonstrate that chronic ozone exposure has profound airway inflammatory effects counteracted by progesterone and progesterone acts synergistically with glucocorticoids in attenuating the airway inflammation dose-dependently. Copyright © 2017 Elsevier Ltd. All rights reserved.

A new species of Hyla (Anura: Hylidae) from the Sierra Mixes, Oaxaca, Mexico, with comments on ontogenetic variation in the tadpoles

USGS Publications Warehouse

Ustach, P.C.; Mendelson, J.R.; McDiarmid, R.W.; Campbell, J.A.

2000-01-01

We describe a new species of Hyla that differs from the similar-loohng species H. pentheter by reaching a larger size, ha\\iing a smaller tympanum, more webbing on the feet, more extensive nuptial excrescences, and a different color pattern on the flanks. \\Ve tentatively place this new species in the phenetic assemblage commonly referred to as the H. bistincta group. \\Ve describe and illlistrate the tadpole and discuss ontogenetic variation among tadpoles, with reference to existing information on tadpoles of other species from the H. bistincta group.

Microgravity-induced modifications of the vestibuloocular reflex in Xenopus laevis tadpoles are related to development and the occurrence of tail lordosis.

PubMed

Horn, Eberhard R

2006-08-01

During space flights, tadpoles of the clawed toad Xenopus laevis occasionally develop upward bended tails (tail lordosis). The tail lordosis disappears after re-entry to 1g within a couple of days. The mechanisms responsible for the induction of the tail lordosis are unknown; physical conditions such as weight de-loading or physiological factors such as decreased vestibular activity in microgravity might contribute. Microgravity (microg) also exerts significant effects on the roll-induced vestibuloocular reflex (rVOR). The rVOR was used to clarify whether tail lordosis is caused by physiological factors, by correlating the occurrence of microg-induced tail lordosis with the extent of microg-induced rVOR modifications. Post-flight recordings from three space flights (D-2 Spacelab mission, STS-55 in 1993; Shuttle-to-Mir mission SMM-06, STS-84 in 1997; French Soyuz taxi flight Andromède to ISS in 2001) were analyzed in these experiments. At onset of microgravity, tadpoles were at stages 25-28, 33-36 or 45. Parameters tested were rVOR gain (ratio between the angular eye movement and the lateral 30 degrees roll) and rVOR amplitude (maximal angular postural change of the eyes during a 360 degrees lateral roll). A ratio of 22-84% of tadpoles developed lordotic tails, depending on the space flight. The overall observation was that the rVOR of tadpoles with normal tails was either not affected by microgravity, or it was enhanced. In contrast, the rVOR of lordotic animals always revealed a depression. In particular, during post-flight days 1-11, tadpoles with lordotic tails from all three groups (25-28, 33-36 and 45) showed a lower rVOR gain and amplitude than the 1g-controls. The rVOR gain and amplitude of tadpoles from the groups 25-28 and 33-36 that developed normal tails was not affected by microgravity while the rVOR of microg-tadpoles from the stage-45 group with normal tails revealed a significant rVOR augmentation. (1) the vestibular system of tadpoles with lordotic

Variation in Chemical Defense Among Natural Populations of Common Toad, Bufo bufo, Tadpoles: the Role of Environmental Factors.

PubMed

Bókony, Veronika; Móricz, Ágnes M; Tóth, Zsófia; Gál, Zoltán; Kurali, Anikó; Mikó, Zsanett; Pásztor, Katalin; Szederkényi, Márk; Tóth, Zoltán; Ujszegi, János; Üveges, Bálint; Krüzselyi, Dániel; Capon, Robert J; Hoi, Herbert; Hettyey, Attila

2016-04-01

Defensive toxins are widespread in nature, yet we know little about how various environmental factors shape the evolution of chemical defense, especially in vertebrates. In this study we investigated the natural variation in the amount and composition of bufadienolide toxins, and the relative importance of ecological factors in predicting that variation, in larvae of the common toad, Bufo bufo, an amphibian that produces toxins de novo. We found that tadpoles' toxin content varied markedly among populations, and the number of compounds per tadpole also differed between two geographical regions. The most consistent predictor of toxicity was the strength of competition, indicating that tadpoles produced more compounds and larger amounts of toxins when coexisting with more competitors. Additionally, tadpoles tended to contain larger concentrations of bufadienolides in ponds that were less prone to desiccation, suggesting that the costs of toxin production can only be afforded by tadpoles that do not need to drastically speed up their development. Interestingly, this trade-off was not alleviated by higher food abundance, as periphyton biomass had negligible effect on chemical defense. Even more surprisingly, we found no evidence that higher predation risk enhances chemical defenses, suggesting that low predictability of predation risk and high mortality cost of low toxicity might select for constitutive expression of chemical defense irrespective of the actual level of predation risk. Our findings highlight that the variation in chemical defense may be influenced by environmental heterogeneity in both the need for, and constraints on, toxicity as predicted by optimal defense theory.

Direct and Indirect Horizontal Transmission of the Antifungal Probiotic Bacterium Janthinobacterium lividum on Green Frog (Lithobates clamitans) Tadpoles.

PubMed

Rebollar, Eria A; Simonetti, Stephen J; Shoemaker, William R; Harris, Reid N

2016-04-01

Amphibian populations worldwide are being threatened by the disease chytridiomycosis, which is caused by Batrachochytrium dendrobatidis To mitigate the effects of B. dendrobatidis, bioaugmentation of antifungal bacteria has been shown to be a promising strategy. One way to implement bioaugmentation is through indirect horizontal transmission, defined as the transfer of bacteria from a host to the environment and to another host. In addition, direct horizontal transmission among individuals can facilitate the spread of a probiotic in a population. In this study, we tested whether the antifungal bacterium Janthinobacterium lividum could be horizontally transferred, directly or indirectly, in a laboratory experiment using Lithobates clamitans tadpoles. We evaluated the ability of J. lividumto colonize the tadpoles' skin and to persist through time using culture-dependent and culture-independent techniques. We also tested whether the addition of J. lividum affected the skin community in L. clamitans tadpoles. We found that transmission occurred rapidly by direct and indirect horizontal transmission, but indirect transmission that included a potential substrate was more effective. Even though J. lividum colonized the skin, its relative abundance on the tadpole skin decreased over time. The inoculation of J. lividum did not significantly alter the skin bacterial diversity of L. clamitans tadpoles, which was dominated by Pseudomonas Our results show that indirect horizontal transmission can be an effective bioaugmentation method. Future research is needed to determine the best conditions, including the presence of substrates, under which a probiotic can persist on the skin so that bioaugmentation becomes a successful strategy to mitigate chytridiomycosis. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Direct and Indirect Horizontal Transmission of the Antifungal Probiotic Bacterium Janthinobacterium lividum on Green Frog (Lithobates clamitans) Tadpoles

PubMed Central

Simonetti, Stephen J.; Shoemaker, William R.; Harris, Reid N.

2016-01-01

Amphibian populations worldwide are being threatened by the disease chytridiomycosis, which is caused by Batrachochytrium dendrobatidis. To mitigate the effects of B. dendrobatidis, bioaugmentation of antifungal bacteria has been shown to be a promising strategy. One way to implement bioaugmentation is through indirect horizontal transmission, defined as the transfer of bacteria from a host to the environment and to another host. In addition, direct horizontal transmission among individuals can facilitate the spread of a probiotic in a population. In this study, we tested whether the antifungal bacterium Janthinobacterium lividum could be horizontally transferred, directly or indirectly, in a laboratory experiment using Lithobates clamitans tadpoles. We evaluated the ability of J. lividum to colonize the tadpoles' skin and to persist through time using culture-dependent and culture-independent techniques. We also tested whether the addition of J. lividum affected the skin community in L. clamitans tadpoles. We found that transmission occurred rapidly by direct and indirect horizontal transmission, but indirect transmission that included a potential substrate was more effective. Even though J. lividum colonized the skin, its relative abundance on the tadpole skin decreased over time. The inoculation of J. lividum did not significantly alter the skin bacterial diversity of L. clamitans tadpoles, which was dominated by Pseudomonas. Our results show that indirect horizontal transmission can be an effective bioaugmentation method. Future research is needed to determine the best conditions, including the presence of substrates, under which a probiotic can persist on the skin so that bioaugmentation becomes a successful strategy to mitigate chytridiomycosis. PMID:26873311

Diversity of the strongly rheophilous tadpoles of Malagasy tree frogs, genus Boophis (Anura, Mantellidae), and identification of new candidate species via larval DNA sequence and morphology

PubMed Central

Randrianiaina, Roger Daniel; Strauß, Axel; Glos, Julian; Vences, Miguel

2012-01-01

Abstract This study provides detailed morphological descriptions of previously unknown tadpoles of the treefrog genus Boophis Tschudi and analyses of habitat preferences of several of these tadpoles in Ranomafana National Park. A total of twenty-two tadpoles determined via DNA barcoding are characterized morphologically herein, fourteen of them for the first time. Twelve of these tadpoles belong to taxonomically undescribed candidate species which in several cases are so far only known from their larval stages. Our data show that the larvae of some of these candidate species occur syntopically yet maintaining a clearly correlated genetic and morphological identity, suggesting that they indeed are true biological and evolutionary species. Tadpoles considered to belong to the “adherent” ecomorphological guild inhabit fast-running waters and their oral disc is commonly to continuously attached to the rocky substrate, supposedly to keep their position in the water current. Some of these species are characterized by the presence of a dorsal gap of papillae and the absence of an upper jaw sheath. This guild includes the tadpoles of the Boophis albipuncatus group (Boophis ankaratra, Boophis schuboeae, Boophis albipunctatus, Boophis sibilans, Boophis luciae), and of the Boophis mandraka group (Boophis sambirano and six candidate species related to this species and to Boophis mandraka). Tadpoles considered belonging to the “suctorial” guild inhabit fast-running waters where they use frequently their oral disc to attach to the substrate. They have an enlarged oral disc without any dorsal gap, including two nominal species (Boophis marojezensis, Boophis vittatus), and five candidate species related to Boophis marojezensis. An ecological analysis of the tadpoles of Boophis luciae, Boophis schuboeae and Boophis marojezensis [Ca51 JQ518198] from Ranomafana National Park did not provide evidence for a clear preference of these tadpoles to the fast flowing microhabitat

Morphology and metamorphosis of Eupsophus calcaratus tadpoles (Anura: Leptodactylidae).

PubMed

Vera Candioti, M F; Ubeda, C; Lavilla, E O

2005-05-01

Eupsophus calcaratus, a leptodactyloid frog from the austral Andean forests of Argentina and Chile, has endotrophic, nidicolous tadpoles. We studied a metamorphic series from Stages 31 to 46 of Gosner's developmental table (1960). Other than the scarce pigmentation, proportionately large eyes, and massive developing hindlimbs, the remaining external characters are similar to those of generalized, exotrophic larvae. At the same time, internal morphology does not reveal any character state attributable to the endotrophic-nidicolous way of life; conversely, structures such as the hyobranchial skeleton and the mandibular cartilages are similar to those of exotrophic-macrophagous tadpoles. The metamorphic process is characterized by the delayed development of diverse structures (e.g., ethmoid region, palatoquadrate, and hyobranchial apparatus), and the retention of some larval characters (e.g., parietal fenestrae, overall absence of ossification) with the absence of development of some "juvenile" characters (e.g., adult otic process, several bones) in metamorphosed individuals. These heterochronic processes and truncation of larval development are related to a shorter larval life (when compared to other species of the austral Andean region) and to the small size at metamorphosis. 2004 Wiley-Liss, Inc.

GENE EXPRESSION PROFILING OF HYPERKERATOTIC SKIN FROM INNER MONGOLIANS CHRONICALLY EXPOSED TO ARSENIC

EPA Science Inventory

Millions of people worldwide have been chronically exposed to arsenic levels in drinking water that greatly exceed the current World Health Organization¿s recommended limit of 10 µg/ml. The skin is a major target of arsenic toxicity, and some of the first clinical signs of chroni...

Cultural perspectives on children's tadpole drawings: at the interface between representation and production.

PubMed

Gernhardt, Ariane; Rübeling, Hartmut; Keller, Heidi

2015-01-01

This study investigated tadpole self-drawings from 183 three- to six-year-old children living in seven cultural groups, representing three ecosocial contexts. Based on assumed general production principles, the influence of cultural norms and values upon specific characteristics of the tadpole drawings was examined. The results demonstrated that children from all cultural groups realized the body-proportion effect in the self-drawings, indicating universal production principles. However, children differed in single drawing characteristics, depending on the specific ecosocial context. Children from Western and non-Western urban educated contexts drew themselves rather tall, with many facial features, and preferred smiling facial expressions, while children from rural traditional contexts depicted themselves significantly smaller, with less facial details, and neutral facial expressions.

Psychophysical Evaluation of Achromatic and Chromatic Vision of Workers Chronically Exposed to Organic Solvents

PubMed Central

Lacerda, Eliza Maria da Costa Brito; Lima, Monica Gomes; Rodrigues, Anderson Raiol; Teixeira, Cláudio Eduardo Correa; de Lima, Lauro José Barata; Ventura, Dora Fix; Silveira, Luiz Carlos de Lima

2012-01-01

The purpose of this paper was to evaluate achromatic and chromatic vision of workers chronically exposed to organic solvents through psychophysical methods. Thirty-one gas station workers (31.5 ± 8.4 years old) were evaluated. Psychophysical tests were achromatic tests (Snellen chart, spatial and temporal contrast sensitivity, and visual perimetry) and chromatic tests (Ishihara's test, color discrimination ellipses, and Farnsworth-Munsell 100 hue test—FM100). Spatial contrast sensitivities of exposed workers were lower than the control at spatial frequencies of 20 and 30 cpd whilst the temporal contrast sensitivity was preserved. Visual field losses were found in 10–30 degrees of eccentricity in the solvent exposed workers. The exposed workers group had higher error values of FM100 and wider color discrimination ellipses area compared to the controls. Workers occupationally exposed to organic solvents had abnormal visual functions, mainly color vision losses and visual field constriction. PMID:22220188

Estrogenic exposure affects metamorphosis and alters sex ratios in the northern leopard frog (Rana pipiens): identifying critically vulnerable periods of development.

PubMed

Hogan, Natacha S; Duarte, Paula; Wade, Michael G; Lean, David R S; Trudeau, Vance L

2008-05-01

During the transformation from larval tadpole to juvenile frog, there are critical periods of metamorphic development and sex differentiation that may be particularly sensitive to endocrine disruption. The aim of the present study was to identify sensitive developmental periods for estrogenic endocrine disruption in the northern leopard frog (Rana pipiens) using short, targeted exposures to the synthetic estrogen, ethinylestradiol (EE2). Post-hatch tadpoles (Gosner stage 27) were exposed over five distinct periods of metamorphosis: early (stage 27-30), mid (stage 30-36), early and mid (stage 27-36), late (stage 36-42), and the entire metamorphic period (chronic; stage 27-42). For each period, animals were sampled immediately following the EE2 exposure and at metamorphic climax (stage 42). The effects of EE2 on metamorphic development and sex differentiation were assessed through measures of length, weight, developmental stage, days to metamorphosis, sex ratios and incidence of gonadal intersex. Our results show that tadpoles exposed to EE2 during mid-metamorphosis were developmentally delayed immediately following exposure and took 2 weeks longer to reach metamorphic climax. In the unexposed groups, there was low proportion (0.15) of intersex tadpoles at stage 30 and gonads appeared to be morphologically distinct (male and female) in all individuals by stage 36. Tadpoles exposed early in development displayed a strong female-biased sex ratio compared to the controls. Moreover, these effects were also seen at metamorphic climax, approximately 2-3 months after the exposure period, demonstrating that transient early life-stage exposure to estrogen can induce effects on the reproductive organs that persist into the beginning of adult life-stages.

Morphology of the elygium and developing umbraculum in the eye of Amietia vertebralis tadpoles.

PubMed

Kruger, Donnavan J D; Weldon, Ché; Minter, Les R; Du Preez, Louis H

2013-05-01

The elygium is a darkly pigmented projection over the pupil of the tadpoles of certain species that live mostly at high altitudes. It has been suggested that this structure shades the retina, protecting it from high UV levels. In post-metamorphic individuals, the elygium is replaced by a structure known as an umbraculum. Confusion arose in the past from the inconsistent use of terminology when referring to these two structures. While they may serve the same function, these structures differ fundamentally in structure and origin. Our investigation of the ultrastructure of the eye in Amietia vertebralis tadpoles, using electron and light microscopy, revealed that the elygium consists of an accumulation of melanophores situated within the inner cornea, whereas the umbraculum is a dorsal extension of the iris pigment epithelium, analogous to the ventral pupillary nodule, which is present in most frog species. In A. vertebralis, the umbraculum starts to develop on the iris of older tadpoles (Gosner [1960] stage 37 Herpetologica 16:183-190), medial to the overlying elygium. A smaller, ventral elygium is also present in this species and is similar in structure to the dorsal elygium. The development of the elygium over a six-month period is also described. Copyright © 2013 Wiley Periodicals, Inc.

The Level of Selenium and Oxidative Stress in Workers Chronically Exposed to Lead.

PubMed

Pawlas, Natalia; Dobrakowski, Michał; Kasperczyk, Aleksandra; Kozłowska, Agnieszka; Mikołajczyk, Agnieszka; Kasperczyk, Sławomir

2016-03-01

The possible beneficial role of selenium (Se) on the oxidative stress induced by lead (Pb) is still unclear in humans. Therefore, the aim of the present study was to explore the associations among the Se levels, chronic Pb exposure, oxidative stress parameters, and parameters characterizing the function of the antioxidant defense system in men who are occupationally exposed to Pb. Based on the median serum Se concentrations, the 324 study subjects were divided into two subgroups: a subgroup with a low Se level (L-Se) and a subgroup with a high Se level (H-Se). The levels of lead (PbB) and zinc protoporphyrin (ZPP) in the blood and the delta-aminolevulinic acid (ALA) level in the urine served as indices of Pb exposure. The PbB level was significantly lower in the H-Se group compared to that in the L-Se group by 6 %. The levels of 8-hydroxyguanosine and lipofuscin (LPS) and the activity of superoxide dismutase were significantly lower in the H-Se group compared to that in the L-Se group by 17, 19, and 11 %, respectively. However, the glutathione level (GSH) and the activities of glutathione peroxidase (GPx) and catalase were significantly higher by 9, 23, and 3 %. Spearman correlations showed positive associations between the Se level and GPx activity and GSH level. A lower serum Se level in chronically Pb-exposed subjects is associated with higher Pb blood levels and an elevated erythrocyte LPS level, which reflects the intensity of oxidative stress. Besides, in a group of Pb-exposed subjects with lower serum Se level, depleted GSH pool and decreased activity of GPx in erythrocytes were reported. However, the present results are inadequate to recommend Se supplementation for chronic lead exposure at higher doses than would be included in a normal diet except for selenium deficiency.

Differential predation on tadpoles influences the potential effects of hybridization between Hyla cinerea and Hyla gratiosa

USGS Publications Warehouse

Gunzburger, M.S.

2005-01-01

Long-term effects of hybridization and introgression are influenced by performance of hybrids in habitats of parental species. The treefrogs Hyla cinerea and Hyla gratiosa, which typically breed in permanent and temporary habitats, respectively, have occasionally hybridized throughout the Southeastern United States. To predict in which of the parental habitats effects of hybridization might be strongest, I performed experiments to evaluate predation on tadpoles of H. cinerea, H. gratiosa, and F1 hybrids with predators typical of the breeding habitats of the parental species. Hybrid tadpoles had lower survival with sunfish than odonate naiad (dragonfly) predators and tended to increase hiding behavior in response to sunfish predation. Tadpoles of H. gratiosa also had higher survival with odonates than sunfish, but H. cinerea had similar survival with both predator types. These results suggest that hybrids are most likely to survive and return to breed in temporary habitats used by H. gratiosa. Thus, hybridization and introgression might be more likely to have adverse effects on populations of H. gratiosa than H. cinerea. Copyright 2005 Society for the Study of Amphibians and Reptiles.

Experimental skeletal teratogenesis in the frog tadpole.

PubMed

Roth, M

1978-01-01

Severe deformities of the hind limb skeleton such as shortening, abnormal curvatures, terminal expansions, curled toes and joint dislocations were produced in frog tadpoles by the osteolathyrogenic principle. Gross-anatomical features of the deformed skeleton and of the respective nervous trunks were studied in specimens cleared according to WILLIAMS' technique. The findings support the previously suggested osteo-neural concept: Experimental skeletal deformities represent adaptations of the bone growth at the organ level to the inadequate extensive growth of the nervous trunks. The neural growth appears to be more severely affected by the teratogen than the bone growth proper.

Cultural perspectives on children’s tadpole drawings: at the interface between representation and production

PubMed Central

Gernhardt, Ariane; Rübeling, Hartmut; Keller, Heidi

2015-01-01

This study investigated tadpole self-drawings from 183 three- to six-year-old children living in seven cultural groups, representing three ecosocial contexts. Based on assumed general production principles, the influence of cultural norms and values upon specific characteristics of the tadpole drawings was examined. The results demonstrated that children from all cultural groups realized the body-proportion effect in the self-drawings, indicating universal production principles. However, children differed in single drawing characteristics, depending on the specific ecosocial context. Children from Western and non-Western urban educated contexts drew themselves rather tall, with many facial features, and preferred smiling facial expressions, while children from rural traditional contexts depicted themselves significantly smaller, with less facial details, and neutral facial expressions. PMID:26136707

Effect of nephrotoxic treatment with gentamicin on rats chronically exposed to uranium.

PubMed

Rouas, Caroline; Stefani, Johanna; Grison, Stéphane; Grandcolas, Line; Baudelin, Cédric; Dublineau, Isabelle; Pallardy, Marc; Gueguen, Yann

2011-01-11

Uranium is a radioactive heavy metal with a predominantly chemical toxicity, affecting especially the kidneys and more particularly the proximal tubular structure. Until now, few experimental studies have examined the effect of chronic low-dose exposure to uranium on kidney integrity: these mainly analyse standard markers such as creatinine and urea, and none has studied the effect of additional co-exposure to a nephrotoxic agent on rats chronically exposed to uranium. The aim of the present study is to examine the potential cumulative effect of treating uranium-exposed rats with a nephrotoxic drug. Neither physiological indicators (diuresis and creatinine clearance) nor standard plasma and urine markers (creatinine, urea and total protein) levels were deteriorated when uranium exposure was combined with gentamicin-induced nephrotoxicity. A histological study confirmed the preferential impact of gentamicin on the tubular structure and showed that uranium did not aggravate the histopathological renal lesions. Finally, the use of novel markers of kidney toxicity, such as KIM-1, osteopontin and kallikrein, provides new knowledge about the nephrotoxicity threshold of gentamicin, and allows us to conclude that under our experimental conditions, low dose uranium exposure did not induce signs of nephrotoxicity or enhance renal sensitivity to another nephrotoxicant. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Deconstructing cartilage shape and size into contributions from embryogenesis, metamorphosis, and tadpole and frog growth.

PubMed

Rose, Christopher S; Murawinski, Danny; Horne, Virginia

2015-06-01

Understanding skeletal diversification involves knowing not only how skeletal rudiments are shaped embryonically, but also how skeletal shape changes throughout life. The pharyngeal arch (PA) skeleton of metamorphosing amphibians persists largely as cartilage and undergoes two phases of development (embryogenesis and metamorphosis) and two phases of growth (larval and post-metamorphic). Though embryogenesis and metamorphosis produce species-specific features of PA cartilage shape, the extents to which shape and size change during growth and metamorphosis remain unaddressed. This study uses allometric equations and thin-plate spline, relative warp and elliptic Fourier analyses to describe shape and size trajectories for the ventral PA cartilages of the frog Xenopus laevis in tadpole and frog growth and metamorphosis. Cartilage sizes scale negatively with body size in both growth phases and cartilage shapes scale isometrically or close to it. This implies that most species-specific aspects of cartilage shape arise in embryogenesis and metamorphosis. Contributions from growth are limited to minor changes in lower jaw (LJ) curvature that produce relative gape narrowing and widening in tadpoles and frogs, respectively, and most cartilages becoming relatively thinner. Metamorphosis involves previously unreported decreases in cartilage size as well as changes in cartilage shape. The LJ becomes slightly longer, narrower and more curved, and the adult ceratohyal emerges from deep within the resorbing tadpole ceratohyal. This contrast in shape and size changes suggests a fundamental difference in the underlying cellular pathways. The observation that variation in PA cartilage shape decreases with tadpole growth supports the hypothesis that isometric growth is required for the metamorphic remodeling of PA cartilages. It also supports the existence of shape-regulating mechanisms that are specific to PA cartilages and that resist local adaptation and phenotypic plasticity. �

Deconstructing cartilage shape and size into contributions from embryogenesis, metamorphosis, and tadpole and frog growth

PubMed Central

Rose, Christopher S; Murawinski, Danny; Horne, Virginia

2015-01-01

Understanding skeletal diversification involves knowing not only how skeletal rudiments are shaped embryonically, but also how skeletal shape changes throughout life. The pharyngeal arch (PA) skeleton of metamorphosing amphibians persists largely as cartilage and undergoes two phases of development (embryogenesis and metamorphosis) and two phases of growth (larval and post-metamorphic). Though embryogenesis and metamorphosis produce species-specific features of PA cartilage shape, the extents to which shape and size change during growth and metamorphosis remain unaddressed. This study uses allometric equations and thin-plate spline, relative warp and elliptic Fourier analyses to describe shape and size trajectories for the ventral PA cartilages of the frog Xenopus laevis in tadpole and frog growth and metamorphosis. Cartilage sizes scale negatively with body size in both growth phases and cartilage shapes scale isometrically or close to it. This implies that most species-specific aspects of cartilage shape arise in embryogenesis and metamorphosis. Contributions from growth are limited to minor changes in lower jaw (LJ) curvature that produce relative gape narrowing and widening in tadpoles and frogs, respectively, and most cartilages becoming relatively thinner. Metamorphosis involves previously unreported decreases in cartilage size as well as changes in cartilage shape. The LJ becomes slightly longer, narrower and more curved, and the adult ceratohyal emerges from deep within the resorbing tadpole ceratohyal. This contrast in shape and size changes suggests a fundamental difference in the underlying cellular pathways. The observation that variation in PA cartilage shape decreases with tadpole growth supports the hypothesis that isometric growth is required for the metamorphic remodeling of PA cartilages. It also supports the existence of shape-regulating mechanisms that are specific to PA cartilages and that resist local adaptation and phenotypic plasticity. PMID

Bullfrog tadpole (Rana catesbeiana) and red swamp crayfish (Procambarus clarkii) predation on early life stages of endangered razorback sucker (Xyrauchen texanus)

USGS Publications Warehouse

Mueller, G.A.; Carpenter, J.; Thornbrugh, D.

2006-01-01

Bullfrog tadpoles (Rana catesbeiana) and red swamp crayfish (Procambarus clarkii) are widespread introduced taxa that are problematic throughout the western United States. Their impact on native amphibians and crustaceans is well documented, but less is known regarding their influence on native fishes. Predator-prey tank tests showed both species consumed eggs and larvae of the endangered razorback sucker (Xyrauchen texanus) in a laboratory setting. Tadpoles consumed 2.2 razorback sucker eggs/d and 1.4 razorback sucker larvae/d, while crayfish ate 6.0 eggs/d and 3.5 larvae/d. Relatively high densities of bullfrog tadpoles and crayfish in razorback sucker spawning areas suggest that these nonnative taxa might pose a threat to the recruitment success of this and other imperiled native fish.

Growth, development and incidence of deformities in amphibian larvae exposed as embryos to naphthenic acid concentrations detected in the Canadian oil sands region.

PubMed

Melvin, Steven D; Trudeau, Vance L

2012-08-01

Naphthenic acids (NA) have been identified as harmful environmental contaminants that influence survival, growth and development of wildlife. Amphibian larvae are particularly susceptible to waterborne contaminants, but little information exists regarding exposure of amphibian embryos or tadpoles to NA. Our results demonstrate that embryos of Lithobates pipiens and Silurana tropicalis exposed to 2-4 mg/l of a commercial NA blend suffer significant reductions (32% and 25%, respectively) in growth and development upon hatching. Increased incidences of deformities were observed in exposed individuals of both species, but were only significant in L. pipiens. Embryos suffered 100% mortality following exposure to 6 mg/l NAs, and narcosis at lower concentrations. LC50 estimates were 4.10 mg/l for 72-h exposure in L. pipiens and 4.13, 3.51, and 2.95 mg/l for 24-, 48-, and 72-h exposure in S. tropicalis. These data suggest that exposure to NAs at environmentally realized concentrations may negatively affect tadpole populations. Copyright © 2012 Elsevier Ltd. All rights reserved.

DETERMINATION OF URINARY TRIVALENT ARSENICALS (MMASIII AND DMASIII) IN INDIVIDUALS CHRONICALLY EXPOSED TO ARSENIC

EPA Science Inventory

DETERMINATION OF URINARY TRIVALENT ARSENICALS (MMAsIII and DMAsIII) IN INDIVIDUALS CHRONICALLY EXPOSED TO ARSENIC.
L. M. Del Razo1, M. Styblo2, W. R. Cullen3, and D.J. Thomas4.
1Toxicology Section, Cinvestav-IPN, Mexico, D.F., 2Univ. North Carolina, Chapel Hill, NC; 3Uni...

A MULTIWAVELENGTH STUDY OF TADPOLE GALAXIES IN THE HUBBLE ULTRA DEEP FIELD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Straughn, Amber N.; Eufrasio, Rafael T.; Gardner, Jonathan P.

2015-12-01

Multiwavelength data are essential in order to provide a complete picture of galaxy evolution and to inform studies of galaxies’ morphological properties across cosmic time. Here we present the results of a multiwavelength investigation of the morphologies of “tadpole” galaxies at intermediate redshift (0.314 < z < 3.175) in the Hubble Ultra Deep Field. These galaxies were previously selected from deep Hubble Space Telescope (HST) F775W data based on their distinct asymmetric knot-plus-tail morphologies. Here we use deep Wide Field Camera 3 near-infrared imaging in addition to the HST optical data in order to study the rest-frame UV/optical morphologies ofmore » these galaxies across the redshift range 0.3 < z < 3.2. This study reveals that the majority of these galaxies do retain their general asymmetric morphology in the rest-frame optical over this redshift range, if not the distinct “tadpole” shape. The average stellar mass of tadpole galaxies is lower than that of field galaxies, with the effect being slightly greater at higher redshift within the errors. Estimated from spectral energy distribution fits, the average age of tadpole galaxies is younger than that of field galaxies in the lower-redshift bin, and the average metallicity is lower (whereas the specific star formation rate for tadpoles is roughly the same as field galaxies across the redshift range probed here). These average effects combined support the conclusion that this subset of galaxies is in an active phase of assembly, either late-stage merging or cold gas accretion causing localized clumpy star formation.« less

Acute toxicity and sublethal effects of the mixture glyphosate (Roundup Active) and Cosmo-Flux 411F to anuran embryos and tadpoles of four Colombian species.

PubMed

Henao Muñoz, Liliana Marcela; Montes Rojas, Claudia Marsela; Bernal Bautista, Manuel Hernando

2015-03-01

Glyphosate is the most widely used herbicide in the world with application in agriculture, forestry, industrial weed control, garden and aquatic environments. However, its use is highly controversial for the possible impact on not-target organisms, such as amphibians, which are vanishing at an alarming and rapid rate. Due to the high solubility in water and ionic nature, the glyphosate requires of surfactants to increase activity. In addition, for the control of coca (Erythroxylum coca) and agricultural weeds in Colombia, formulated glyphosate is mixed and sprayed with the adjuvant Cosmo-Flux 411F to increase the penetration and activity of the herbicide. This study evaluates the acute toxic and sublethal effects (embryonic development, tadpole body size, tadpole swimming performance) of the mixture of the formulated glyphosate Roundup Active and Cosmo-Flux 411F to anuran embryos and tadpoles of four Colombian species under 96h laboratory standard tests and microcosms, which are more similar to field conditions as they include soil, sand and macrophytes. In the laboratory, embryos and tadpoles of Engystomops pustulosus were the most tolerant (LC50 = 3904 microg a.e./L; LC50=2 799 pg a.e./L, respectively), while embryos and tadpoles of Hypsiboas crepitans (LC50=2 203 microg a.e./L; LC50=1424 microgg a.e./L, respectively) were the most sensitive. R. humboldti and R. marina presented an intermediate toxicity. Embryos were significantly more tolerant to the mixture than tadpoles, which could be likely attributed to the exclusion of chemicals by the embryonic membranes and the lack of organs, such as gills, which are sensitive to surfactants. Sublethal effects were observed for the tadpole body size, but not for the embryonic development and tadpole swimming performance. In microcosms, no toxicity (LC50 could not be estimated), or sublethal responses were observed at concentrations up to fourfold (14.76 kg glyphosate a.e./ha) the highest field application rate of 3

Telomere Length in Aged Mayak PA Nuclear Workers Chronically Exposed to Internal Alpha and External Gamma Radiation.

PubMed

Scherthan, Harry; Sotnik, Natalia; Peper, Michel; Schrock, Gerrit; Azizova, Tamara; Abend, Michael

2016-06-01

Telomeres consist of GC-rich DNA repeats and the "shelterin" protein complex that together protect chromosome ends from fusion and degradation. Telomeres shorten with age due to incomplete end replication and upon exposure to environmental and intrinsic stressors. Exposure to ionizing radiation is known to modulate telomere length. However, the response of telomere length in humans chronically exposed to radiation is poorly understood. Here, we studied relative telomere length (RTL) by IQ-FISH to leukocyte nuclei in a group of 100 workers from the plutonium production facility at the Mayak Production Association (PA) who were chronically exposed to alpha-emitting ((239)Pu) radiation and/or gamma (photon) radiation, and 51 local residents serving as controls, with a similar mean age of about 80 years. We applied generalized linear statistical models adjusted for age at biosampling and the second exposure type on a linear scale and observed an age-dependent telomere length reduction. In those individuals with the lowest exposure, a significant reduction of about 20% RTL was observed, both for external gamma radiation (≤1 Gy) and internal alpha radiation (≤0.05-0.1 Gy to the red bone marrow). In highly exposed individuals (>0.1 Gy alpha, 1-1.5 Gy gamma), the RTL was similar to control. Stratification by gender revealed a significant (∼30%) telomere reduction in low-dose-exposed males, which was absent in females. While the gender differences in RTL may reflect different working conditions, lifestyle and/or telomere biology, absence of a dose response in the highly exposed individuals may reflect selection against cells with short telomeres or induction of telomere-protective effects. Our observations suggest that chronic systemic exposure to radiation leads to variable dose-dependent effects on telomere length.

Chronic elevation of phosphocholine containing lipids in mice exposed to Gulf War agents pyridostigmine bromide and permethrin.

PubMed

Abdullah, Laila; Evans, James E; Montague, Hannah; Reed, Jon M; Moser, Ann; Crynen, Gogce; Gonzalez, Ariel; Zakirova, Zuchra; Ross, Ivan; Mullan, Chris; Mullan, Michael; Ait-Ghezala, Ghania; Crawford, Fiona

2013-01-01

For two decades, 25% of the veterans who served in the 1991 Gulf War (GW) have been living with Gulf War Illness (GWI), a chronic multisymptom illness. Evidence suggests that brain structures involved in cognitive function may be affected in GWI. Gulf War agents such as the acetylcholinesterase (AChE) inhibitor pyridostigmine bromide (PB) and the pesticide permethrin (PER) are considered key etiogenic factors in GWI. We therefore developed a mouse model of GW agent exposure by co-administering PB and PER and showed that this model exhibits cognitive impairment and anxiety, and increased astrogliosis at chronic post-exposure time-points. Since GW agents inhibit AChE, we hypothesized that PB+PER exposure will modulate phosphatidylcholine (PC) and sphingomyelin (SM), which are reservoirs of phosphocholine required for endogenous ACh synthesis. Lipidomic analyses showed that PC and SM were elevated in the brains of exposed compared to control mice. Brain ether PC (ePC) species were increased but lyso-platelet activating factors (lyso-PAF) that are products of ePC were decreased in exposed animals compared to controls. Catalase expression (a marker for peroxisomes) was increased in GW agent exposed mice compared to controls. Ether PC and lyso-PAF modulation was also evident in the plasma of GW agent exposed mice compared to controls. These studies suggest peroxisomal and lysosomal dysfunction in the brain at a chronic post-exposure timepoint following GW agent exposure. Our studies provide a new direction for GWI research, which will be useful for developing suitable therapies for treating GWI. © 2013 Elsevier Inc. All rights reserved.

Inversion of left-right asymmetry alters performance of Xenopus tadpoles in nonlateralized cognitive tasks.

PubMed

Blackiston, Douglas J; Levin, Michael

2013-08-01

Left-right behavioural biases are well documented across the animal kingdom, and handedness has long been associated with cognitive performance. However, the relationship between body laterality and cognitive ability is poorly understood. The embryonic pathways dictating normal left-right patterning have been molecularly dissected in model vertebrates, and numerous genetic and pharmacological treatments now facilitate experimental randomization or reversal of the left-right axis in these animals. Several recent studies showed a link between brain asymmetry and strongly lateralized behaviours such as eye use preference. However, links between laterality of the body and performance on cognitive tasks utilizing nonlateralized cues remain unknown. Xenopus tadpoles are an established model for the study of early left-right patterning, and protocols were recently developed to quantitatively evaluate learning and memory in these animals. Using an automated testing and training platform, we tested wild-type, left-right-randomized and left-right-reversed tadpoles for their ability to learn colour cues in an automated assay. Our results indicate that animals with either randomization or reversal of somatic left-right patterning learned more slowly than wild-type siblings, although all groups were able to reach the same performance optimum given enough training sessions. These results are the first analysis of the link between body laterality and learning of nonlateralized cues, and they position the Xenopus tadpole as an attractive and tractable model for future studies of the links between asymmetry of the body, lateralization of the brain and behaviour.

DNA DAMAGE IN BUCCAL EPITHELIAL CELLS FROM INDIVIDUALS CHRONICALLY EXPOSED TO ARSENIC VIA DRINKING WATER IN INNER MONGOLIA, CHINA

EPA Science Inventory

The purpose of this pilot study was to assess DNA damage in buccal cells from individuals chronically exposed to arsenic via drinking water in Ba Men, Inner Mongolia. Buccal cells were collected from 19 Ba Men residents exposed to arsenic at 527.5 ? 23.7 g/L (mean ? SEM) and ...

Estimation of a closed population size of tadpoles in temporary pond.

PubMed

Lima, M S C S; Pederassi, J; Souza, C A S

2018-05-01

The practice of capture-recapture to estimate the diversity is well known to many animal groups, however this practice in the larval phase of anuran amphibians is incipient. We aimed at evaluating the Lincoln estimator, Venn diagram and Bayes theorem in the inference of population size of a larval phase anurocenose from lotic environment. The adherence of results was evaluated using the Kolmogorov-Smirnov test. The marking of tadpoles for later recapture and methods measurement was made with eosin methylene blue. When comparing the results of Lincoln-Petersen estimator corresponding to the Venn diagram and Bayes theorem, we detected percentage differences per sampling, i.e., the proportion of sampled anuran genera is kept among the three methods, although the values are numerically different. By submitting these results to the Kolmogorov-Smirnov test we have found no significant differences. Therefore, no matter the estimator, the measured value is adherent and estimates the total population. Together with the marking methodology, which did not change the behavior of tadpoles, the present study helps to fill the need of more studies on larval phase of amphibians in Brazil, especially in semi-arid northeast.

Frankixalus, a New Rhacophorid Genus of Tree Hole Breeding Frogs with Oophagous Tadpoles

PubMed Central

Biju, S. D.; Mahony, Stephen; Kamei, Rachunliu G.; Thomas, Ashish; Shouche, Yogesh; Raxworthy, Christopher J.; Meegaskumbura, Madhava; Bocxlaer, Ines Van

2016-01-01

Despite renewed interest in the biogeography and evolutionary history of Old World tree frogs (Rhacophoridae), this family still includes enigmatic frogs with ambiguous phylogenetic placement. During fieldwork in four northeastern states of India, we discovered several populations of tree hole breeding frogs with oophagous tadpoles. We used molecular data, consisting of two nuclear and three mitochondrial gene fragments for all known rhacophorid genera, to investigate the phylogenetic position of these new frogs. Our analyses identify a previously overlooked, yet distinct evolutionary lineage of frogs that warrants recognition as a new genus and is here described as Frankixalus gen. nov. This genus, which contains the enigmatic ‘Polypedates’ jerdonii described by Günther in 1876, forms the sister group of a clade containing Kurixalus, Pseudophilautus, Raorchestes, Mercurana and Beddomixalus. The distinctiveness of this evolutionary lineage is also corroborated by the external morphology of adults and tadpoles, adult osteology, breeding ecology, and life history features. PMID:26790105

Theory of chromatography of partially cyclic polymers: Tadpole-type and manacle-type macromolecules.

PubMed

Vakhrushev, Andrey V; Gorbunov, Alexei A

2016-02-12

A theory of chromatography is developed for partially cyclic polymers of tadpole- and manacle-shaped topological structures. We present exact equations for the distribution coefficient K at different adsorption interactions; simpler approximate formulae are also derived, relevant to the conditions of size-exclusion, adsorption, and critical chromatography. Theoretical chromatograms of heterogeneous partially cyclic polymers are simulated, and conditions for good separation by topology are predicted. According to the theory, an effective SEC-radius of tadpoles and manacles is mostly determined by the molar mass M, and by the linear-cyclic composition. In the interactive chromatography, the effect of molecular topology on the retention becomes significant. At the critical interaction point, partial dependences K(Mlin) and K(Mring) are qualitatively different: while being almost independent of Mlin, K increases with Mring. This behavior could be realized in critical chromatography-for separation of partially cyclic polymers by the number and molar mass of cyclic elements. Copyright © 2015 Elsevier B.V. All rights reserved.

Fear is the mother of invention: anuran embryos exposed to predator cues alter life-history traits, post-hatching behaviour and neuronal activity patterns.

PubMed

Gazzola, Andrea; Brandalise, Federico; Rubolini, Diego; Rossi, Paola; Galeotti, Paolo

2015-12-01

Neurophysiological modifications associated to phenotypic plasticity in response to predators are largely unexplored, and there is a gap of knowledge on how the information encoded in predator cues is processed by prey sensory systems. To explore these issues, we exposed Rana dalmatina embryos to dragonfly chemical cues (kairomones) up to hatching. At different times after hatching (up to 40 days), we recorded morphology and anti-predator behaviour of tadpoles from control and kairomone-treated embryo groups as well as their neural olfactory responses, by recording the activity of their mitral neurons before and after exposure to a kairomone solution. Treated embryos hatched later and hatchlings were smaller than control siblings. In addition, the tadpoles from the treated group showed a stronger anti-predator response than controls at 10 days (but not at 30 days) post-hatching, though the intensity of the contextual response to the kairomone stimulus did not differ between the two groups. Baseline neuronal activity at 30 days post-hatching, as assessed by the frequency of spontaneous excitatory postsynaptic events and by the firing rate of mitral cells, was higher among tadpoles from the treated versus the control embryo groups. At the same time, neuronal activity showed a stronger increase among tadpoles from the treated versus the control group after a local kairomone perfusion. Hence, a different contextual plasticity between treatments at the neuronal level was not mirrored by the anti-predator behavioural response. In conclusion, our experiments demonstrate ontogenetic plasticity in tadpole neuronal activity after embryonic exposure to predator cues, corroborating the evidence that early-life experience contributes to shaping the phenotype at later life stages. © 2015. Published by The Company of Biologists Ltd.

To eat or not to eat: ontogeny of hypothalamic feeding controls and a role for leptin in modulating life-history transition in amphibian tadpoles.

PubMed

Bender, Melissa Cui; Hu, Caroline; Pelletier, Chris; Denver, Robert J

2018-03-28

Many animal life histories entail changing feeding ecology, but the molecular bases for these transitions are poorly understood. The amphibian tadpole is typically a growth and dispersal life-history stage. Tadpoles are primarily herbivorous, and they capitalize on growth opportunities to reach a minimum body size to initiate metamorphosis. During metamorphic climax, feeding declines, at which time the gastrointestinal (GI) tract remodels to accommodate the carnivorous diet of the adult frog. Here we show that anorexigenic hypothalamic feeding controls are absent in the tadpole, but develop during metamorphosis concurrent with the production of the satiety signal leptin. Before metamorphosis there is a large increase in leptin mRNA in fat tissue. Leptin receptor mRNA increased during metamorphosis in the preoptic area/hypothalamus, the key brain region involved with the control of food intake and metabolism. This corresponded with an increase in functional leptin receptor, as evidenced by induction of socs3 mRNA and phosphorylated STAT3 immunoreactivity, and suppression of feeding behaviour after injection of recombinant frog leptin. Furthermore, we found that immunoneutralization of leptin in tadpoles at metamorphic climax caused them to resume feeding. The absence of negative regulation of food intake in the tadpole allows the animal to maximize growth prior to metamorphosis. Maturation of leptin-responsive neural circuits suppresses feeding during metamorphosis to facilitate remodelling of the GI tract. © 2018 The Author(s).

Lung inflammation biomarkers and lung function in children chronically exposed to arsenic

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olivas-Calderón, Edgar, E-mail: edgar_olivascalderon@hotmail.com; School of Medicine, University Juarez of Durango, Gomez Palacio, Durango; Recio-Vega, Rogelio, E-mail: rrecio@yahoo.com

Evidence suggests that exposure to arsenic in drinking water during early childhood or in utero has been associated with an increase in respiratory symptoms or diseases in the adulthood, however only a few studies have been carried out during those sensitive windows of exposure. Recently our group demonstrated that the exposure to arsenic during early childhood or in utero in children was associated with impairment in the lung function and suggested that this adverse effect could be due to a chronic inflammation response to the metalloid. Therefore, we designed this cross-sectional study in a cohort of children associating lung inflammatorymore » biomarkers and lung function with urinary As levels. A total of 275 healthy children were partitioned into four study groups according with their arsenic urinary levels. Inflammation biomarkers were measured in sputum by ELISA and the lung function was evaluated by spirometry. Fifty eight percent of the studied children were found to have a restrictive spirometric pattern. In the two highest exposed groups, the soluble receptor for advanced glycation end products' (sRAGE) sputum level was significantly lower and matrix metalloproteinase-9 (MMP-9) concentration was higher. When the biomarkers were correlated to the urinary arsenic species, negative associations were found between dimethylarsinic (DMA), monomethylarsonic percentage (%MMA) and dimethylarsinic percentage (%DMA) with sRAGE and positive associations between %DMA with MMP-9 and with the MMP-9/tissue inhibitor of metalloproteinase (TIMP-1) ratio. In conclusion, chronic arsenic exposure of children negatively correlates with sRAGE, and positively correlated with MMP-9 and MMP-9/TIMP-1 levels, and increases the frequency of an abnormal spirometric pattern. Arsenic-induced alterations in inflammatory biomarkers may contribute to the development of restrictive lung diseases. - Highlights: • First study in children evaluating lung inflammatory biomarkers and As

The rostral medulla of bullfrog tadpoles contains critical lung rhythmogenic and chemosensitive regions across metamorphosis.

PubMed

Reed, Mitchell D; Iceman, Kimberly E; Harris, Michael B; Taylor, Barbara E

2018-06-08

The development of amphibian breathing provides insight into vertebrate respiratory control mechanisms. Neural oscillators in the rostral and caudal medulla drive ventilation in amphibians, and previous reports describe ventilatory oscillators and CO 2 sensitive regions arise during different stages of amphibian metamorphosis. However, inconsistent findings have been enigmatic, and make comparisons to potential mammalian counterparts challenging. In the current study we assessed amphibian central CO 2 responsiveness and respiratory rhythm generation during two different developmental stages. Whole-nerve recordings of respiratory burst activity in cranial and spinal nerves were made from intact or transected brainstems isolated from tadpoles during early or late stages of metamorphosis. Brainstems were transected at the level of the trigeminal nerve, removing rostral structures including the nucleus isthmi, midbrain, and locus coeruleus, or transected at the level of the glossopharyngeal nerve, removing the putative buccal oscillator and caudal medulla. Removal of caudal structures stimulated the frequency of lung ventilatory bursts and revealed a hypercapnic response in normally unresponsive preparations derived from early stage tadpoles. In preparations derived from late stage tadpoles, removal of rostral or caudal structures reduced lung burst frequency, while CO 2 responsiveness was retained. Our results illustrate that structures within the rostral medulla are capable of sensing CO 2 throughout metamorphic development. Similarly, the region controlling lung ventilation appears to be contained in the rostral medulla throughout metamorphosis. This work offers insight into the consistency of rhythmic respiratory and chemosensitive capacities during metamorphosis. Copyright © 2018. Published by Elsevier Inc.

Complete mitochondrial DNA sequence of a tadpole shrimp (Triops cancriformis) and analysis of museum samples.

PubMed

Umetsu, Kazuo; Iwabuchi, Naruki; Yuasa, Isao; Saitou, Naruya; Clark, Paul F; Boxshall, Geoff; Osawa, Motoki; Igarashi, Keiji

2002-12-01

The complete mitochondrial DNA (mtNDA) of the tadpole shrimp Triops cancriformis was sequenced. The sequence consisted of 15,101 bp with an A+T content of 69%. Its gene arrangement was identical with those sequences of the water flea (Daphnia pulex) and giant tiger prawn (Penaeus monodon), whereas it differed from that of the brine shrimp (Artemia franciscana) in the arrangement of its genes for tRNAs. Phylogenetic analysis revealed T. cancriformis to be more closely related to the water flea than to the brine shrimp and giant tiger prawn. We also compared the 16S rRNA sequences of five formalin-fixed tadpole shrimps that had been collected in five different locations and stored in a museum. The sequence divergence was in the range of 0-1.51%, suggesting that those samples were closely related to each other.

Chronic Traumatic Encephalopathy in Blast-Exposed Military Veterans and a Blast Neurotrauma Mouse Model

PubMed Central

Goldstein, Lee E.; Fisher, Andrew M.; Tagge, Chad A.; Zhang, Xiao-Lei; Velisek, Libor; Sullivan, John A.; Upreti, Chirag; Kracht, Jonathan M.; Ericsson, Maria; Wojnarowicz, Mark W.; Goletiani, Cezar J.; Maglakelidze, Giorgi M.; Casey, Noel; Moncaster, Juliet A.; Minaeva, Olga; Moir, Robert D.; Nowinski, Christopher J.; Stern, Robert A.; Cantu, Robert C.; Geiling, James; Blusztajn, Jan K.; Wolozin, Benjamin L.; Ikezu, Tsuneya; Stein, Thor D.; Budson, Andrew E.; Kowall, Neil W.; Chargin, David; Sharon, Andre; Saman, Sudad; Hall, Garth F.; Moss, William C.; Cleveland, Robin O.; Tanzi, Rudolph E.; Stanton, Patric K.; McKee, Ann C.

2013-01-01

Blast exposure is associated with traumatic brain injury (TBI), neuropsychiatric symptoms, and long-term cognitive disability. We examined a case series of postmortem brains from U.S. military veterans exposed to blast and/or concussive injury. We found evidence of chronic traumatic encephalopathy (CTE), a tau protein–linked neurodegenerative disease, that was similar to the CTE neuropathology observed in young amateur American football players and a professional wrestler with histories of concussive injuries. We developed a blast neurotrauma mouse model that recapitulated CTE-linked neuropathology in wild-type C57BL/6 mice 2 weeks after exposure to a single blast. Blast-exposed mice demonstrated phosphorylated tauopathy, myelinated axonopathy, microvasculopathy, chronic neuroinflammation, and neurodegeneration in the absence of macroscopic tissue damage or hemorrhage. Blast exposure induced persistent hippocampal-dependent learning and memory deficits that persisted for at least 1 month and correlated with impaired axonal conduction and defective activity-dependent long-term potentiation of synaptic transmission. Intracerebral pressure recordings demonstrated that shock waves traversed the mouse brain with minimal change and without thoracic contributions. Kinematic analysis revealed blast-induced head oscillation at accelerations sufficient to cause brain injury. Head immobilization during blast exposure prevented blast-induced learning and memory deficits. The contribution of blast wind to injurious head acceleration may be a primary injury mechanism leading to blast-related TBI and CTE. These results identify common pathogenic determinants leading to CTE in blast-exposed military veterans and head-injured athletes and additionally provide mechanistic evidence linking blast exposure to persistent impairments in neurophysiological function, learning, and memory. PMID:22593173

Chronic traumatic encephalopathy in blast-exposed military veterans and a blast neurotrauma mouse model.

PubMed

Goldstein, Lee E; Fisher, Andrew M; Tagge, Chad A; Zhang, Xiao-Lei; Velisek, Libor; Sullivan, John A; Upreti, Chirag; Kracht, Jonathan M; Ericsson, Maria; Wojnarowicz, Mark W; Goletiani, Cezar J; Maglakelidze, Giorgi M; Casey, Noel; Moncaster, Juliet A; Minaeva, Olga; Moir, Robert D; Nowinski, Christopher J; Stern, Robert A; Cantu, Robert C; Geiling, James; Blusztajn, Jan K; Wolozin, Benjamin L; Ikezu, Tsuneya; Stein, Thor D; Budson, Andrew E; Kowall, Neil W; Chargin, David; Sharon, Andre; Saman, Sudad; Hall, Garth F; Moss, William C; Cleveland, Robin O; Tanzi, Rudolph E; Stanton, Patric K; McKee, Ann C

2012-05-16

Blast exposure is associated with traumatic brain injury (TBI), neuropsychiatric symptoms, and long-term cognitive disability. We examined a case series of postmortem brains from U.S. military veterans exposed to blast and/or concussive injury. We found evidence of chronic traumatic encephalopathy (CTE), a tau protein-linked neurodegenerative disease, that was similar to the CTE neuropathology observed in young amateur American football players and a professional wrestler with histories of concussive injuries. We developed a blast neurotrauma mouse model that recapitulated CTE-linked neuropathology in wild-type C57BL/6 mice 2 weeks after exposure to a single blast. Blast-exposed mice demonstrated phosphorylated tauopathy, myelinated axonopathy, microvasculopathy, chronic neuroinflammation, and neurodegeneration in the absence of macroscopic tissue damage or hemorrhage. Blast exposure induced persistent hippocampal-dependent learning and memory deficits that persisted for at least 1 month and correlated with impaired axonal conduction and defective activity-dependent long-term potentiation of synaptic transmission. Intracerebral pressure recordings demonstrated that shock waves traversed the mouse brain with minimal change and without thoracic contributions. Kinematic analysis revealed blast-induced head oscillation at accelerations sufficient to cause brain injury. Head immobilization during blast exposure prevented blast-induced learning and memory deficits. The contribution of blast wind to injurious head acceleration may be a primary injury mechanism leading to blast-related TBI and CTE. These results identify common pathogenic determinants leading to CTE in blast-exposed military veterans and head-injured athletes and additionally provide mechanistic evidence linking blast exposure to persistent impairments in neurophysiological function, learning, and memory.

Evaluation of the serum catalase and myeloperoxidase activities in chronic arsenic-exposed individuals and concomitant cytogenetic damage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Banerjee, Mayukh; Banerjee, Nilanjana; Ghosh, Pritha

2010-11-15

Chronic arsenic exposure through contaminated drinking water is a major environmental health issue. Chronic arsenic exposure is known to exert its toxic effects by a variety of mechanisms, of which generation of reactive oxygen species (ROS) is one of the most important. A high level of ROS, in turn, leads to DNA damage that might ultimately culminate in cancer. In order to keep the level of ROS in balance, an array of enzymes is present, of which catalase (CAT) and myeloperoxidase (MPO) are important members. Hence, in this study, we determined the activities of these two enzymes in the seramore » and chromosomal aberrations (CA) in peripheral blood lymphocytes in individuals exposed and unexposed to arsenic in drinking water. Arsenic in drinking water and in urine was used as a measure of exposure. Our results show that individuals chronically exposed to arsenic have significantly higher CAT and MPO activities and higher incidence of CA. We found moderate positive correlations between CAT and MPO activities, induction of CA and arsenic in urine and water. These results indicate that chronic arsenic exposure causes higher CAT and MPO activities in serum that correlates with induction of genetic damage. We conclude that the serum levels of these enzymes might be used as biomarkers of early arsenic exposure induced disease much before the classical dermatological symptoms of arsenicosis begin to appear.« less

Impacts of the herbicide butachlor on the larvae of a paddy field breeding frog (Fejervarya limnocharis) in subtropical Taiwan

USGS Publications Warehouse

Liu, Wan-Yi; Wang, Ching-Yuh; Wang, Tsu-Shing; Fellers, Gary M.; Lai, Bo-Chi; Kam, Yeong-Choy

2011-01-01

Butachlor is the most commonly used herbicide on paddy fields in Taiwan and throughout Southeast Asia. Since paddy fields provide habitat for pond breeding amphibians, we examined growth, development, time to metamorphosis, and survival of alpine cricket frog tadpoles (Fejervarya limnocharis) exposed to environmentally realistic concentrations of butachlor. We documented negative impacts of butachlor on survival, development, and time to metamorphosis, but not on tadpole growth. The 96 h LC50 for tadpoles was 0.87 mg/l, much lower than the 4.8 mg/l recommended dosage for application to paddy fields. Even given the rapid breakdown of butachlor, tadpoles would be exposed to concentrations in excess of their 96 h LC50 for an estimated 126 h. We also documented DNA damage (genotoxicity) in tadpoles exposed to butachlor at concentrations an order of magnitude less than the 4.8 mg/l recommended application rate. We did not find that butachlor depressed cholinesterase activity of tadpoles, unlike most organophosphorus insecticides. We conclude that butachlor is likely to have widespread negative impacts on amphibians occupying paddy fields with traditional herbicide application.

Impacts of the herbicide butachlor on the larvae of a paddy field breeding frog (Fejervarya limnocharis) in subtropical Taiwan.

PubMed

Liu, Wan-Yi; Wang, Ching-Yuh; Wang, Tsu-Shing; Fellers, Gary M; Lai, Bo-Chi; Kam, Yeong-Choy

2011-03-01

Butachlor is the most commonly used herbicide on paddy fields in Taiwan and throughout Southeast Asia. Since paddy fields provide habitat for pond breeding amphibians, we examined growth, development, time to metamorphosis, and survival of alpine cricket frog tadpoles (Fejervarya limnocharis) exposed to environmentally realistic concentrations of butachlor. We documented negative impacts of butachlor on survival, development, and time to metamorphosis, but not on tadpole growth. The 96 h LC(50) for tadpoles was 0.87 mg/l, much lower than the 4.8 mg/l recommended dosage for application to paddy fields. Even given the rapid breakdown of butachlor, tadpoles would be exposed to concentrations in excess of their 96 h LC(50) for an estimated 126 h. We also documented DNA damage (genotoxicity) in tadpoles exposed to butachlor at concentrations an order of magnitude less than the 4.8 mg/l recommended application rate. We did not find that butachlor depressed cholinesterase activity of tadpoles, unlike most organophosphorus insecticides. We conclude that butachlor is likely to have widespread negative impacts on amphibians occupying paddy fields with traditional herbicide application.

Description of the tadpoles of two endemic frogs: the Phu Luang cascade frog Odorrana aureola (Anura: Ranidae) and the Isan big-headed frog Limnonectes isanensis (Anura: Dicroglossidae) from northeastern Thailand.

PubMed

Ampai, Natee; Rujirawan, Attapol; Arkajag, Jirachai; Mcleod, David S; Aowphol, Anchalee

2015-07-07

We describe the external morphology of the tadpoles of two frogs endemic to Thailand: the Phu Luang cascade frog    (Odorrana aureola) and the Isan big-headed frog (Limnonectes isanensis) from the type localities in the Phu Luang Wildlife Sanctuary, Loei Province, northeastern Thailand. Morphological and genetic characters (16S rRNA) were used to identify specimen and match tadpoles to the adults. Detailed descriptions of external morphology and coloration in life are provided for both species. We provide a brief discussion of the ecology of these tadpoles and a comparison to previously published data from tadpoles of closely related taxa. Additionally, we provide evidence for the utility of larval morphology in resolving the taxonomic puzzles presented by cryptic species complexes.

Analysis of thyroid hormone receptor {beta}A mRNA expression in Xenopus laevis tadpoles as a means to detect agonism and antagonism of thyroid hormone action

DOE Office of Scientific and Technical Information (OSTI.GOV)

Opitz, Robert; Lutz, Ilka; Nguyen, Ngoc-Ha

2006-04-01

Amphibian metamorphosis represents a unique biological model to study thyroid hormone (TH) action in vivo. In this study, we examined the utility of thyroid hormone receptors {alpha} (TR{alpha}) and {beta}A (TR{beta}A) mRNA expression patterns in Xenopus laevis tadpoles as molecular markers indicating modulation of TH action. During spontaneous metamorphosis, only moderate changes were evident for TR{alpha} gene expression whereas a marked up-regulation of TR{beta}A mRNA occurred in hind limbs (prometamorphosis), head (late prometamorphosis), and tail tissue (metamorphic climax). Treatment of premetamorphic tadpoles with 1 nM 3,5,3'-triiodothyronine (T3) caused a rapid induction of TR{beta}A mRNA in head and tail tissue withinmore » 6 to 12 h which was maintained for at least 72 h after initiation of T3 treatment. Developmental stage had a strong influence on the responsiveness of tadpole tissues to induce TR{beta}A mRNA during 24 h treatment with thyroxine (0, 1, 5, 10 nM T4) or T3 (0, 1, 5, 10 nM). Premetamorphic tadpoles were highly sensitive in their response to T4 and T3 treatments, whereas sensitivity to TH was decreased in early prometamorphic tadpoles and strongly diminished in late prometamorphic tadpoles. To examine the utility of TR{beta}A gene expression analysis for detection of agonistic and antagonistic effects on T3 action, mRNA expression was assessed in premetamorphic tadpoles after 48 h of treatment with the synthetic agonist GC-1 (0, 10, 50, 250 nM), the synthetic antagonist NH-3 (0, 40, 200, 1000 nM), and binary combinations of NH-3 (0, 40, 200, 1000 nM) and T3 (1 nM). All tested concentrations of GC-1 as well as the highest concentration of NH-3 caused an up-regulation of TR{beta}A expression. Co-treatment with NH-3 and T3 revealed strong antagonistic effects by NH-3 on T3-induced TR{beta}A mRNA up-regulation. Results of this study suggest that TR{beta}A mRNA expression analysis could serve as a sensitive molecular testing approach to study

Acute and joint toxicity of three agrochemicals to Chinese tiger frog (Hoplobatrachus chinensis) tadpoles

PubMed Central

WEI, Li; SHAO, Wei-Wei; DING, Guo-Hua; FAN, Xiao-Li; YU, Miao-Ling; LIN, Zhi-Hua

2014-01-01

We studied acute and joint toxicity of three different agrochemicals (chlorantraniliprole, flubendiamide-abamectin and penoxsulam) to Chinese tiger frog (Hoplobatrachus chinensis) tadpoles with the method of stability water tests. Results showed that the three agrochemicals increased tadpole mortality. For acute toxicity, the LC50 values after 24, 48 and 72 h of chlorantraniliprole, flubendiamide-abamectin and penoxsulam exposure were 5.37, 4.90 and 4.68 mg/L; 0.035, 0.025 and 0.021 mg/L; 1.74, 1.45 and 1.29 mg/L, respectively. The safety concentrations (SC) of chlorantraniliprole, flubendiamide-abamectin and penoxsulam to the tadpoles were 1.23, 0.30 and 0.003 mg/L, respectively. Based on these findings, chlorantraniliprole and penoxsulam were moderately toxic, while flubendiamide-abamectin was highly toxic. All pairwise joint toxicity tests showed moderate toxicity. The LC50 values after 24, 48 and 72 h of exposure were 7.08, 6.61 and 6.03 mg/L for chlorantraniliprole+penoxsulam, with corresponding values of 2.455, 2.328 and 2.183 mg/L for chlorantraniliprole+flubendiamide-abamectin, and 1.132, 1.084 and 1.050 mg/L for penoxsulam+flubendiamide-abamectin, with safe concentrations of 1.73, 0.63 and 0.30 mg/L, respectively. For toxic evaluations of pairwise combinations of the three agrochemicals, only the joint toxicity of chlorantraniliprole and flubendiamide-abamectin after 24 h was found to be synergistic, whereas all other tests were antagonistic. Our findings provide valuable information on the toxic effects of agrochemicals on amphibians and how various types of agrochemicals can be reasonably used in agricultural areas. PMID:25017745

Acute and joint toxicity of three agrochemicals to Chinese tiger frog (Hoplobatrachus chinensis) tadpoles.

PubMed

Wei, Li; Shao, Wei-Wei; Ding, Guo-Hua; Fan, Xiao-Li; Yu, Miao-Ling; Lin, Zhi-Hua

2014-07-01

We studied acute and joint toxicity of three different agrochemicals (chlorantraniliprole, flubendiamide-abamectin and penoxsulam) to Chinese tiger frog (Hoplobatrachus chinensis) tadpoles with the method of stability water tests. Results showed that the three agrochemicals increased tadpole mortality. For acute toxicity, the LC50 values after 24, 48 and 72 h of chlorantraniliprole, flubendiamide-abamectin and penoxsulam exposure were 5.37, 4.90 and 4.68 mg/L; 0.035, 0.025 and 0.021 mg/L; 1.74, 1.45 and 1.29 mg/L, respectively. The safety concentrations (SC) of chlorantraniliprole, flubendiamide-abamectin and penoxsulam to the tadpoles were 1.23, 0.30 and 0.003 mg/L, respectively. Based on these findings, chlorantraniliprole and penoxsulam were moderately toxic, while flubendiamide-abamectin was highly toxic. All pairwise joint toxicity tests showed moderate toxicity. The LC50 values after 24, 48 and 72 h of exposure were 7.08, 6.61 and 6.03 mg/L for chlorantraniliprole+penoxsulam, with corresponding values of 2.455, 2.328 and 2.183 mg/L for chlorantraniliprole+flubendiamide-abamectin, and 1.132, 1.084 and 1.050 mg/L for penoxsulam+flubendiamide-abamectin, with safe concentrations of 1.73, 0.63 and 0.30 mg/L, respectively. For toxic evaluations of pairwise combinations of the three agrochemicals, only the joint toxicity of chlorantraniliprole and flubendiamide-abamectin after 24 h was found to be synergistic, whereas all other tests were antagonistic. Our findings provide valuable information on the toxic effects of agrochemicals on amphibians and how various types of agrochemicals can be reasonably used in agricultural areas.

Specific limb abnormalities induced by hydrogen peroxide in tadpoles of Indian jumping frog, Polypedates maculatus.

PubMed

Mahapatra, P K; Mohanty-Hejmadi, P; Chainy, G B

2001-11-01

Hydrogen peroxide (H2O2), one of the reactive oxygen intermediates (ROI) and a potential inducer of nuclear transcription factors induces consistent type of abnormal limb development (truncated with bent skeletal elements) in the tadpoles of Indian jumping frog, Polypedates maculatus.

Living in fast-flowing water: morphology of the gastromyzophorous tadpole of the bufonid Rhinella quechua (R. veraguensis group).

PubMed

Aguayo, R; Lavilla, E O; Vera Candioti, M F; Camacho, T

2009-12-01

We describe the bufonid gastromyzophorous tadpoles of Rhinella quechua from montane forest streams in Bolivia. Specimens were cleared and stained, and the external morphology, buccopharyngeal structures, and the musculoskeletal system were studied. These tadpoles show a combination of some traits common in Rhinella larvae (e.g., emarginate oral disc with large ventral gap in the marginal papillae, labial tooth row formula 2/3, prenarial ridge, two infralabial papillae, quadratoorbital commissure present, larval otic process absent, mm. mandibulolabialis superior, interhyoideus posterior, and diaphragmatopraecordialis absent, m. subarcualis rectus I composed of three slips), some traits apparently exclusive for the described species of the R. veraguensis group (e.g., second anterior labial tooth row complete, lingual papillae absent, adrostral cartilages present), and some traits that are shared with other gastromyzophorous tadpoles (e.g., enlarged oral disc, short and wide articular process of the palatoquadrate, several muscles inserting on the abdominal sucker). In the context of the substantial taxonomic and nomenclatural changes that the former genus Bufo has undergone, and despite the conspicuous morphological differences related to the presence of an abdominal sucker, the larval morphology of R. quechua supports including it in the genus Rhinella and placing it close to species of the R. veraguensis assemblage. (c) 2009 Wiley-Liss, Inc.

Brane boxes, anomalies, bending, and tadpoles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leigh, R.G.; Rozali, M.

1999-01-01

Certain classes of chiral four-dimensional gauge theories may be obtained as the world volume theories of D5-branes are suspended between networks of NS5-branes, the so-called brane box models. In this paper, we derive the stringy consistency conditions placed on these models, and show that they are equivalent to an anomaly cancellation of the gauge theories. We derive these conditions in the orbifold theories which are {ital T} dual to the elliptic brane box models. Specifically, we show that the expression for tadpoles for unphysical twisted Ramond-Ramond 4-form fields in the orbifold theory are proportional to the gauge anomalies of themore » brane box theory. Thus string consistency is equivalent to world volume gauge anomaly cancellation. Furthermore, we find additional cylinder amplitudes which give the {beta} functions of the gauge theory. We show how these correspond to bending of the NS-branes in the brane box theory. {copyright} {ital 1998} {ital The American Physical Society}« less

Further notes on the natural history of the South American pepper frog, Leptodactylus labyrinthicus (Spix, 1824) (Anura, Leptodactylidae).

PubMed

Silva, W R; Giaretta, A A

2008-05-01

Leptodactylus labyrinthicus tadpoles reach a large size in the nest through consumption of trophic eggs. We previously suggested that the trophic eggs are laid just after amplexus has finished, but our new data do not support this hypothesis. We also present further details on the natural history of the species with regard to breeding activity, spawning site, retreats and the ability of tadpoles in preying upon fully-growth heterospecific tadpoles. We also show that the tadpoles are mainly nocturnal and take diurnal refuges. We collected the data in Brazil in three localities within the Cerrado Biome. We examined burrows used by L. labyrinthicus males, verified if females still contained mature eggs just after released from amplexus, and tested the ability of tadpoles in preying fully-growth heterospecific tadpoles. Field observations and experiments were conducted on tadpole activity time, hiding behaviour and level of susceptibility to predation by the bird leaf-scrapers in four sheltering situations. Reproduction could start before the first rains; this may be advantageous by allowing the tadpoles to exploit eggs of other frogs. We found one floating nest built in a temporary pool. The nest of the species is normally circumscribed in an excavated basin beside the water body. Adult males were found during the day with their head-out of the entrance of underwater burrows, which were perforations through dense root mats beside calling/spawning sites. Probably, these burrows in permanently water-filled soil are actively excavated by males. Females released all their eggs during the amplexus, so trophic eggs are not produced by the currently-accepted mechanism. Fully-grown heterospecific tadpoles were not preyed upon by L. labyrinthicus tadpoles, which can prey only slow-moving newly hatched ones. Field tadpoles took shelter under mud/dead leaves during daylight and became exposed on the bottom at night. Free-ranging leaf-scrapers removed dead leaves from a pool with

Neuro-inflammatory response in rats chronically exposed to (137)Cesium.

PubMed

Lestaevel, Philippe; Grandcolas, Line; Paquet, François; Voisin, Philippe; Aigueperse, Jocelyne; Gourmelon, Patrick

2008-03-01

After the Chernobyl nuclear accident, behavioural disorders and central nervous system diseases were frequently observed in populations living in the areas contaminated by (137)Cs. Until now, these neurological disturbances were not elucidated, but the presence of a neuro-inflammatory response could be one explanation. Rats were exposed for 3 months to drinking water contaminated with (137)Cs at a dose of 400Bqkg(-1), which is similar to that ingested by the population living in contaminated areas in the former USSR countries. Pro-inflammatory and anti-inflammatory cytokine genes were assessed by real-time PCR in the frontal cortex and the hippocampus. At this level of exposure, gene expression of TNF-alpha and IL-6 increased in the hippocampus and gene expression of IL-10 increased in the frontal cortex. Concentration of TNF-alpha, measured by ELISA assays, was also increased in the hippocampus. The central NO-ergic pathway was also studied: iNOS gene expression and cNOS activity were significantly increased in the hippocampus. In conclusion, this study showed for the first time that sub-chronic exposure with post-accidental doses of (137)Cs leads to molecular modifications of pro- and anti-inflammatory cytokines and NO-ergic pathway in the brain. This neuro-inflammatory response could contribute to the electrophysiological and biochemical alterations observed after chronic exposure to (137)Cs.

The phytotelm tadpoles of Microhyla arboricola (Anura: Microhylidae) from Vietnam, with comments on reproductive biology and development.

PubMed

Vassilieva, Anna B; Trounov, Vitaly L; Poyarkov, Nikolay A Jr; Galoyan, Eduard A

2017-03-28

The reproductive biology of Microhyla arboricola (Microhylidae) was studied in two regions of the southern Annamite Mountains in Vietnam. M. arboricola is an obligate phytotelm-breeder that reproduces in water-filled tree hollows in montane evergreen forests. Clutches are attached above the water level in the hollows and contain 5-37 pigmented, relatively large eggs. Larvae hatch at markedly advanced stages and develop in water until metamorphosis is completed. The developing tadpoles are obligately oophagous and feed on conspecific eggs and embryos. M. arboricola tadpoles differ from tadpoles of pond-dwelling Microhyla species in their external morphology (extremely long tails, dorsolateral position of the eyes, dark pigmentation), digestive tract morphology (large, extensible larval stomach and short intestine), and oral morphology. The larval chondrocranium and hyobranchiumof M. arboricola is described. M. arboricola shares its habitat with other hollow-breeding species of anurans. To date, M. arboricola is the only known arboreal species of the genus Microhyla that has a unique reproductive mode. The ecological niche of this species differs greatly from those occupied by other microhylids of Indochinese Peninsula.

Possible cause for altered spatial cognition of prepubescent rats exposed to chronic radiofrequency electromagnetic radiation.

PubMed

Narayanan, Sareesh Naduvil; Kumar, Raju Suresh; Karun, Kalesh M; Nayak, Satheesha B; Bhat, P Gopalakrishna

2015-10-01

The effects of chronic and repeated radiofrequency electromagnetic radiation (RFEMR) exposure on spatial cognition and hippocampal architecture were investigated in prepubescent rats. Four weeks old male Wistar rats were exposed to RF-EMR (900 MHz; SAR-1.15 W/kg with peak power density of 146.60 μW/cm(2)) for 1 h/day, for 28 days. Followed by this, spatial cognition was evaluated by Morris water maze test. To evaluate the hippocampal morphology; H&E staining, cresyl violet staining, and Golgi-Cox staining were performed on hippocampal sections. CA3 pyramidal neuron morphology and surviving neuron count (in CA3 region) were studied using H&E and cresyl violet stained sections. Dendritic arborization pattern of CA3 pyramidal neuron was investigated by concentric circle method. Progressive learning abilities were found to be decreased in RF-EMR exposed rats. Memory retention test performed 24 h after the last training revealed minor spatial memory deficit in RF-EMR exposed group. However, RF-EMR exposed rats exhibited poor spatial memory retention when tested 48 h after the final trial. Hirano bodies and Granulovacuolar bodies were absent in the CA3 pyramidal neurons of different groups studied. Nevertheless, RF-EMR exposure affected the viable cell count in dorsal hippocampal CA3 region. RF-EMR exposure influenced dendritic arborization pattern of both apical and basal dendritic trees in RF-EMR exposed rats. Structural changes found in the hippocampus of RF-EMR exposed rats could be one of the possible reasons for altered cognition.

Developmental and Thyroid Hormone Regulation of the DNA Methyltransferase 3a Gene in Xenopus Tadpoles

PubMed Central

Kyono, Yasuhiro; Sachs, Laurent M.; Bilesimo, Patrice; Wen, Luan

2016-01-01

Thyroid hormone is essential for normal development in vertebrates. In amphibians, T3 controls metamorphosis by inducing tissue-specific gene regulation programs. A hallmark of T3 action is the modification of chromatin structure, which underlies changes in gene transcription. We found that mRNA for the de novo DNA methyltransferase (DNMT) dnmt3a, but not dnmt1, increased in the brain of Xenopus tadpoles during metamorphosis in parallel with plasma [T3]. Addition of T3 to the rearing water caused a time-dependent increase in dnmt3a mRNA in tadpole brain, tail, and hind limb. By analyzing data from a genome-wide analysis of T3 receptor (TR) binding in tadpole tail, we identified several putative T3 response elements (TREs) within the dnmt3a locus. Using in vitro DNA binding, transient transfection-reporter, and chromatin immunoprecipitation assays for TRs, we identified two functional TREs at −7.1 kb and +5.1 kb relative to the dnmt3a transcription start site. Sequence alignment showed that these TREs are conserved between two related frog species, X. laevis and X. tropicalis, but not with amniotes. Our previous findings showed that this gene is directly regulated by liganded TRs in mouse brain, and whereas the two mouse TREs are conserved among Eutherian mammals, they are not conserved in Xenopus species. Thus, although T3 regulation of dnmt3a may be an ancient pathway in vertebrates, the genomic sites responsible for hormone regulation may have diverged or arisen by convergent evolution. We hypothesize that direct T3 regulation of dnmt3a may be an important mechanism for modulating global changes in DNA methylation. PMID:27779916

Apoptotic cell death in the central nervous system of Bufo arenarum tadpoles induced by cypermethrin.

PubMed

Casco, V H; Izaguirre, M F; Marín, L; Vergara, M N; Lajmanovich, R C; Peltzer, P; Soler, A Peralta

2006-05-01

Tadpoles of the toad Bufo arenarum treated with cypermethrin (CY) at concentrations above 39 mug CY/L showed dose-dependent apoptotic cell death in immature cells of the central nervous system as demonstrated by morphometric analysis, the TUNEL method, and DNA fragmentation assay. Light-and electron-microscopic studies showed structural alterations in the intermediate and marginal layers of the brain. Immature cerebral tissue showed cellular shrinkage, nuclear fragmentation and increase of intercellular spaces. In this study we demonstrated high toxicity of CY to larval stages of Bufo arenarum. Our results show that doses lower than those used in routine insecticide applications can cause massive apoptosis in the immature cells of the central nervous system. These results coincide with our previous studies in Physalaemus biligonigerus, confirming the severe toxic effects of CY to the central nervous system of anuran species from Argentina. This may increase the mortality index in wild animals and contribute to the loss of biodiversity in our agroecosystems. We postulate that CY induces apoptosis in central nervous system cells of Bufo arenarum tadpoles by specific neurotoxic mechanisms.

Low levels of the herbicide atrazine alter sex ratios and reduce metamorphic success in Rana pipiens tadpoles raised in outdoor mesocosms.

PubMed

Langlois, Valérie S; Carew, Amanda C; Pauli, Bruce D; Wade, Michael G; Cooke, Gerard M; Trudeau, Vance L

2010-04-01

There are conflicting reports regarding the effects of atrazine (ATZ) on amphibian development. Therefore, further studies are needed to examine the potential mechanisms of action of ATZ in amphibians. Our aim in this study was to determine whether low concentrations of ATZ affect gonadal development and metamorphosis in the Northern leopard frog, Rana pipiens. Tadpoles were exposed in outdoor mesocosms to nominal concentrations of 0.1 and 1.8 microg/L of formulated ATZ from Gosner stage 27 (G27) to metamorphic climax (G42). Exposure to 17alpha-ethinylestradiol (EE2; 1.5 microg/L) provided a positive control for induction of testicular oocytes in males. Endocrine-related gene expression and gonadal histopathology were examined at G42 and in a subset of premetamorphic G34 tadpoles that failed to metamorphose. Gonadal gross morphology revealed that the 1.8-microg/L ATZ treatment produced 20% more females compared with the control. Histologic analysis revealed that 22% of EE2-treated males had testicular oocytes, whereas none were observed in any animals from the control or either ATZ groups. ATZ increased brain estrogen receptor alpha mRNA to 2.5 times that of the control at premetamorphosis and altered liver levels of 5beta-reductase activity at metamorphosis. In contrast, brain aromatase mRNA level and activity did not change. ATZ treatments significantly reduced metamorphic success (number of animals reaching metamorphosis) without affecting body weight, snout-vent length, or age at metamorphosis. Gene expression analysis indicated that ATZ decreased the expression of deiodinase type 3 in the tail at premetamorphosis. Our study indicates that exposure to low concentrations of ATZ in experimental mesocosms alters gonadal differentiation and metamorphosis in developing R. pipiens.

Effects of glyphosate and its commercial formulation, Roundup® Ultramax, on liver histology of tadpoles of the neotropical frog, Leptodactylus latrans (amphibia: Anura).

PubMed

Bach, Nadia C; Marino, Damián J G; Natale, Guillermo S; Somoza, Gustavo M

2018-07-01

In the last years, the agricultural expansion has led to an increased use of pesticides, with glyphosate as the most widely used worldwide. This is also the situation in Argentina, where glyphosate formulations are the most commercialized herbicides. It is known that glyphosate formulations are much more toxic than the active ingredient, and this difference in toxicity can be attributed to the adjuvants present in the formula. In this context, the aim of the present study was to evaluate and compare sub-lethal histological effects of the glyphosate formulation Roundup Ultramax and glyphosate active ingredient on Leptodactylus latrans tadpoles at Gosner-stage 36. Semi-static bioassays were performed using 96 h of exposure with Roundup Ultramax formulation (RU; 0.37-5.25 mg a.e./L), glyphosate (GLY; 3-300 mg/L), and a control group. RU exposure showed an increment in the melanomacrophagic cells (MMc) and melanomacrophagic centers (MMCs) from 0.37 mg a.e./L. GLY exposure showed a significant increment in the number of MMc from 15 mg/L, and of MMCs from 3 mg/L. Also, histopathological lesions were observed in the liver of tadpoles exposed to both, GLY and RU. These lesions included: lipidosis and hepatic congestion, but only RU showed significant differences respect to control, with a LOEC value of 2.22 mg a.e./L for both effects. In sum, this study represents the first evidence of adverse effects of glyphosate and RU formulation on the liver of anuran larvae at concentrations frequently found in the environment. Copyright © 2018 Elsevier Ltd. All rights reserved.

Laser correlation spectrometry: a new approach to organizing oncological screening for a population exposed to chronic irradiation

NASA Astrophysics Data System (ADS)

Akleyev, Alexander; Pashkov, Igor; Kisselyov, Mikhail; Noskin, Leonid A.

1999-12-01

The issue of stochastic effects of radiation exposure (mostly leukemia and cancer), and early detection of malignant tumors, as a key aspect of the problem, is of crucial importance to the population chronically exposed due to the activities of the Mayak Production Association in the Urals region, Russia). Given the large number of exposed population, screening is considered to be the most expedient method to organize medical observation of exposed persons. As was shown by the results of medical examinations conducted for 1 391 residents of the Techa riverside villages, laser correlation spectrometry (LCS) of blood plasma has proved to be a highly effective screening method for early (pre-clinical) detection of malignant neoplasms and pre-cancerous conditions. It was established that LC- spectra of blood plasma in persons with cancer and pre- cancer can easily be differentiated from non-cancer conditions. Of particular diagnostic significance is the high-frequency range of the spectrum. The development of a diagnostic algorithm has allowed to carry out a computer- based classification of blood plasma LC spectra as a component of exposed population health monitoring system.

Changes in serum thioredoxin among individuals chronically exposed to arsenic in drinking water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Yuanyuan; Gao, Yanhui; Zhao, Lijun

2012-02-15

It is well known that oxidative damage plays a key role in the development of chronic arsenicosis. There is a complex set of mechanisms of redox cycling in vivo to protect cells from the damage. In this study, we examined the differences in the levels of serum thioredoxin1 (TRX1) among individuals exposed to different levels of arsenic in drinking water and detected early biomarkers of arsenic poisoning before the appearance of skin lesions. A total of 157 subjects from endemic regions of China were selected and divided into arsenicosis group with skin lesions (total intake of arsenic: 8.68–45.71 mg-year) andmore » non-arsenicosis group without skin lesions, which further divided into low (0.00–1.06 mg-year), medium (1.37–3.55 mg-year), and high (4.26–48.13 mg-year) arsenic exposure groups. Concentrations of serum TRX1 were analyzed by an ELISA method. Levels of water arsenic and urinary speciated arsenics, including inorganic arsenic (iAs), monomethylated arsenic (MMA), and dimethylated arsenic (DMA), were determined by hydride generation atomic absorption spectrometry. Our results showed that the levels of serum TRX1 in arsenicosis patients were significantly higher than that of the subjects who were chronically exposed to arsenic, but without skin lesions. A positive correlation was seen between the levels of serum TRX1 and the total water arsenic intake or the levels of urinary arsenic species. The results of this study indicate that arsenic exposure could significantly change the levels of human serum TRX1, which can be detected before arsenic-specific dermatological symptoms occur. This study provides further evidence on revealing the mechanism of arsenic toxicity. -- Highlights: ► Three regions are selected as the areas affected by endemic arsenicosis of China. ► We first examine changes in serum TRX1 among individuals exposed to arsenic. ► A positive correlation was seen between serum TRX1 and total water arsenic intake. ► The same

[Adaptability of abnormal tadpole (Rana chensinensis) to water pH, salinity and alkalinity in Changbai Mountain of China].

PubMed

Yang, Fuyi; Shao, Qingchun; Li, Jinglin; Chen, Guoshuang

2004-08-01

Under field condition with 16-18 degree C water temperature, single-factor acute toxicity test was used to study the toxicity effects of water pH, salinity and carbonate-alkalinity on abnormal tadpole (R. chensinensis). The results showed that when the water salinity was 0.18 g x L(-1), carbonate-alkalinity was 1.41 mmol x L(-1), and water pH was 4.3-9.7, the survival rate of abnormal tadpole within 96 hours was not affected. The upper limit of LC50 for the pH within 24, 48, 72 and 96 hours was 10.33, 10.18, 10.08 and 10.02, and the prescribed minimum was 3.92, 4.07, 4.11 and 4.16, respectively. The upper limit of LC0 was 9.95, 9.80, 9.70 and 9.70, and the prescribed minimum was 4.23, 4.45, 4.30 and 4.30, and that of LC100 was 10.70, 10.55, 10.45 and 10.33, and the prescribed minimum was 3.55, 3.70, 3.92 and 4.03, respectively. The survival rate of abnormal tadpole within 96 hours was not affected in the water salinity between 2.0-3.0 g x L(-1). When water pH was 7.0-8.5 and carbonate-alkalinity was 1.41 mmol x L(-1), the LC50 of the salinity within 24, 48, 72 and 96 hours was 8.21, 7.25, 5.17 and 3.70 g x L(-1), the LC0 was 7.14, 6.00, 2.67 and 2.20 g x L(-1), and the LC100 was 9.98, 9.00, 7.67 and 5.20 g x L(-1), respectively, while the SC was 1.70 g x L(-1). Under the same water pH and when the water salinity was 0.18 g x L(-1), the LC50 of carbonate-alkalinity within 24, 48, 72 and 96 hours was 14.36, 11.83, 10.35, and 7.68 mmol x L(-1), the LC0 was 8.76, 8.51, 4.65 and 3.88 mmol x L(-1), and the LC100 was 19.96, 15.14, 16.05 and 11.48 mmol x L(-1), respectively, while the SC was 1.70 mmol x L(-1). The survival rate of abnormal tadpole (R. chensinensis) was decreased with increasing water pH, salinity and carbonate-alkalinity. The optimum water salinity and carbonate-alkalinity to the survival and the growth of abnormal tadpole (R. chensinensis) were below 2.0 g x L(-1) and 3.0 mmol x L(-1), respectively, and water pH was between 6.0 and 9.0.

Developmental changes in head movement kinematics during swimming in Xenopus laevis tadpoles.

PubMed

Hänzi, Sara; Straka, Hans

2017-01-15

During the post-embryonic developmental growth of animals, a number of physiological parameters such as locomotor performance, dynamics and behavioural repertoire are adjusted to match the requirements determined by changes in body size, proportions and shape. Moreover, changes in movement parameters also cause changes in the dynamics of self-generated sensory stimuli, to which motion-detecting sensory systems have to adapt. Here, we examined head movements and swimming kinematics of Xenopus laevis tadpoles with a body length of 10-45 mm (developmental stage 46-54) and compared these parameters with fictive swimming, recorded as ventral root activity in semi-intact in vitro preparations. Head movement kinematics was extracted from high-speed video recordings of freely swimming tadpoles. Analysis of these locomotor episodes indicated that the swimming frequency decreased with development, along with the angular velocity and acceleration of the head, which represent self-generated vestibular stimuli. In contrast, neither head oscillation amplitude nor forward velocity changed with development despite the ∼3-fold increase in body size. The comparison between free and fictive locomotor dynamics revealed very similar swimming frequencies for similarly sized animals, including a comparable developmental decrease of the swimming frequency. Body morphology and the motor output rhythm of the spinal central pattern generator therefore develop concurrently. This study thus describes development-specific naturalistic head motion profiles, which form the basis for more natural stimuli in future studies probing the vestibular system. © 2017. Published by The Company of Biologists Ltd.

Distribution and accumulation of metals in tadpoles inhabiting the metalliferous streams of eastern Chalkidiki, northeast Greece.

PubMed

Kelepertzis, Efstratios; Argyraki, Ariadne; Valakos, Efstratios; Daftsis, Emmanouil

2012-10-01

The present study investigates the accumulation of heavy metals [copper (Cu), lead (Pb), zinc (Zn), magnesium (Mn), cadmium (Cd), nickel (Ni), and chromium (Cr)] in tadpoles inhabiting the metalliferous streams flowing within the Asprolakkas River basin (northeast Chalkidiki peninsula, Greece) and the effect of potentially harmful elements in stream water and sediment on the corresponding levels in their tissue. Animals were collected from six sampling sites influenced by a wide range of surface water and stream sediment trace element concentrations. The results of the chemical analyses showed that tadpoles accumulated significant levels of all of the examined metals. The range of whole-body mean measured concentrations were (in dry mass) as follows: Cu (46-182 mg/kg), Pb (103-4,490 mg/kg), Zn (494-11,460 mg/kg), Mn (1,620-13,310 mg/kg), Cd (1.2-82 mg/kg), Ni (57-163 mg/kg), and Cr (38-272 mg/kg). The mean concentrations of Pb, Zn, Mn, Ni, Cr, and Cd in Kokkinolakkas stream, which drains a currently active mining area, were the highest ever reported in tadpoles. Our results indicate that whole-body levels of Pb, Zn, Cu, and Cd increase with stream sediment concentrations and that these organisms tend to accumulate metals bound to Fe and Mn oxides. In addition, high dissolved concentrations and significant concentrations associated with more labile geochemical phases of sediments for specific metals were contributing factors determining whole-body levels. Given the observed bioconcentration factors, as well as the correlation with sediment concentrations, it is proposed that these organisms could be considered as bioindicators of environmental contamination and may be used for monitoring purposes within this metal-rich zone and, perhaps, within other rivers affected by metal mining.

Biomarker analysis of American toad (Anaxyrus americanus) and grey tree frog (Hyla versicolor) tadpoles following exposure to atrazine.

EPA Science Inventory

The objective of the current study was to use a biomarker-based approach to investigate the influence of atrazine exposure on American toad (Anaxyrus americanus) and grey tree frog (Hyla versicolor) tadpoles. Atrazine is one of the most frequently detected herbicides in environme...

Proximal renal tubular injury in rats sub-chronically exposed to low fluoride concentrations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cárdenas-González, Mariana C.; Del Razo, Luz M.; Barrera-Chimal, Jonatan

2013-11-01

Fluoride is usually found in groundwater at a very wide range of concentration between 0.5 and 25 ppm. At present, few studies have assessed the renal effects of fluoride at environmentally relevant concentrations. Furthermore, most of these studies have used insensitive and nonspecific biomarkers of kidney injury. The aim of this study was to use early and sensitive biomarkers to evaluate kidney injury after fluoride exposure to environmentally relevant concentrations. Recently weaned male Wistar rats were exposed to low (15 ppm) and high (50 ppm) fluoride concentrations in drinking water for a period of 40 days. At the end ofmore » the exposure period, kidney injury biomarkers were measured in urine and renal mRNA expression levels were assessed by real time RT-PCR. Our results showed that the urinary kidney injury molecule (Kim-1), clusterin (Clu), osteopontin (OPN) and heat shock protein 72 excretion rate significantly increased in the group exposed to the high fluoride concentration. Accordingly, fluoride exposure increased renal Kim-1, Clu and OPN mRNA expression levels. Moreover, there was a significant dose-dependent increase in urinary β-2-microglobulin and cystatin-C excretion rate. Additionally, a tendency towards a dose dependent increase of tubular damage in the histopathological light microscopy findings confirmed the preferential impact of fluoride on the tubular structure. All of these changes occurred at early stages in which, the renal function was not altered. In conclusion using early and sensitive biomarkers of kidney injury, we were able to found proximal tubular alterations in rats sub-chronically exposed to fluoride. - Highlights: • Exposure to low concentrations of fluoride induced proximal tubular injury • Increase in urinary Kim-1, Clu, OPN and Hsp72 in 50 ppm fluoride-exposed group • Increase in urinary B2M and CysC in 15 and 50 ppm fluoride-exposed groups • Fluoride exposure increased renal Kim, Clu and OPN mRNA expression

Changes in serum thioredoxin among individuals chronically exposed to arsenic in drinking water.

PubMed

Li, Yuanyuan; Gao, Yanhui; Zhao, Lijun; Wei, Yudan; Feng, Hongqi; Wang, Cheng; Wei, Wei; Ding, Yunpeng; Sun, Dianjun

2012-02-15

It is well known that oxidative damage plays a key role in the development of chronic arsenicosis. There is a complex set of mechanisms of redox cycling in vivo to protect cells from the damage. In this study, we examined the differences in the levels of serum thioredoxin1 (TRX1) among individuals exposed to different levels of arsenic in drinking water and detected early biomarkers of arsenic poisoning before the appearance of skin lesions. A total of 157 subjects from endemic regions of China were selected and divided into arsenicosis group with skin lesions (total intake of arsenic: 8.68-45.71mg-year) and non-arsenicosis group without skin lesions, which further divided into low (0.00-1.06mg-year), medium (1.37-3.55mg-year), and high (4.26-48.13mg-year) arsenic exposure groups. Concentrations of serum TRX1 were analyzed by an ELISA method. Levels of water arsenic and urinary speciated arsenics, including inorganic arsenic (iAs), monomethylated arsenic (MMA), and dimethylated arsenic (DMA), were determined by hydride generation atomic absorption spectrometry. Our results showed that the levels of serum TRX1 in arsenicosis patients were significantly higher than that of the subjects who were chronically exposed to arsenic, but without skin lesions. A positive correlation was seen between the levels of serum TRX1 and the total water arsenic intake or the levels of urinary arsenic species. The results of this study indicate that arsenic exposure could significantly change the levels of human serum TRX1, which can be detected before arsenic-specific dermatological symptoms occur. This study provides further evidence on revealing the mechanism of arsenic toxicity. Copyright © 2011 Elsevier Inc. All rights reserved.

Inhibition of ovarian development by methyl farnesoate in the tadpole shrimp, Triops longicaudatus.

PubMed

Tsukimura, B; Nelson, W K; Linder, C J

2006-06-01

Methyl farnesoate (MF), a putative crustacean hormone, is the immediate precursor of insect juvenile hormone III (JHIII) in the biosynthetic pathway. We examined whether MF, shown to inhibit adult metamorphosis in several crustacean species, is a juvenilizing factor in the tadpole shrimp, Triops longicaudatus. Oocyte production was chosen as a parameter for measuring reproductive development. MF was administered to juveniles by ingestion via biological vector (Artemia nauplii), MF-coated food pellets, and MF liposome food pellets. Artemia were incubated in 30 microl of 5 microg/ml MF. The MF-coated and MF liposome pellets were prepared with MF concentrations ranging between 0.1 microg/g and 10 microg/g MF by weight. Groups of tadpole shrimp were treated with these vectors from the time of hatching for 5 or 10 days in laboratory and field studies. The treatment groups of all the MF vectors showed reductions in oocyte production. Lower concentrations of MF (0.75 microg/g-3.8 microg/g MF) appeared to have a physiological effect on fecundity, but higher concentrations (10 microg/g MF) reduced somatic growth. MF-coated pellets (1 microg/g MF) administered to adults (after 5 days) caused no difference in oocyte production. The observed reductions of fecundity and the disparity of results between MF treatment on juveniles and adults suggest that MF may regulate ovarian development.

Heterogeneous distribution of G protein alpha subunits in the main olfactory and vomeronasal systems of Rhinella (Bufo) arenarum tadpoles.

PubMed

Jungblut, Lucas D; Paz, Dante A; López-Costa, Juan J; Pozzi, Andrea G

2009-10-01

We evaluated the presence of G protein subtypes Galpha(o), Galpha(i2), and Galpha(olf) in the main olfactory system (MOS) and accessory or vomeronasal system (VNS) of Rhinella (Bufo) arenarum tadpoles, and here describe the fine structure of the sensory cells in the olfactory epithelium (OE) and vomeronasal organ (VNO). The OE shows olfactory receptor neurons (ORNs) with cilia in the apical surface, and the vomeronasal receptor neurons (VRNs) of the VNO are covered with microvilli. Immunohistochemistry detected the presence of at least two segregated populations of ORNs throughout the OE, coupled to Galpha(olf) and Galpha(o). An antiserum against Galpha(i2) was ineffective in staining the ORNs. In the VNO, Galpha(o) neurons stained strongly but lacked immunoreactivity to any other Galpha subunit in all larval stages analyzed. Western blot analyses and preabsorption experiments confirmed the specificity of the commercial antisera used. The functional significance of the heterogeneous G-protein distribution in R. arenarum tadpoles is not clear, but the study of G- protein distributions in various amphibian species is important, since this vertebrate group played a key role in the evolution of tetrapods. A more complete knowledge of the amphibian MOS and VNS would help to understand the functional organization and evolution of vertebrate chemosensory systems. This work demonstrates, for the first time, the existence of a segregated distribution of G-proteins in the OE of R. arenarum tadpoles.

Respiratory tract pathology and cytokine imbalance in clinically healthy children chronically and sequentially exposed to air pollutants.

PubMed

Calderón-Garcidueñas, L; Devlin, R B; Miller, F J

2000-11-01

Chronic exposure of children to a complex mixture of air pollutants leads to recurrent episodes of upper and lower respiratory tract injury. An altered nasal mucociliary apparatus leaves the distal acinar airways more vulnerable to reactive gases and particulate matter (PM). The heterogeneity of structure in the human lung can impart significant variability in the distribution of ozone dose and particle deposition; this, in turn, influences the extent of epithelial injury and repair in chronically exposed children. Cytokines are low-molecular-weight proteins that act as intercellular mediators of inflammatory reactions, including lung injury of various etiologies. Cytokines are involved in generating inflammatory responses that contribute to injury at the lung epithelial and endothelial barriers. Mexico City is a 20-million-person megacity with severe air pollution problems. Southwest Metropolitan Mexico City (SWMMC) atmosphere is characterized by a complex mixture of air pollutants, including ozone, PM, and aldehydes. There is radiological evidence that significant lower respiratory tract damage is taking place in clinically healthy children chronically and sequentially exposed to air pollutants while growing up in SWMMC. We hypothesize that there is an imbalanced and dysregulated cytokine network in SWMMC children with overproduction of proinflammatory cytokines and cytokines involved in lung tissue repair and fibrosis. The nature of the sustained imbalance among the different cytokines ultimately determines the final lung histopathology, which would include subchronic inflammation, emphysema, and fibrosis. Cytokines likely would reach the systemic circulation and produce systemic effects. Individuals with an underlying respiratory or cardiovascular disease are less able to maintain equilibrium of the precarious cytokine networks.

Microbiological evaluation of chronic blepharitis among Iranian veterans exposed to mustard gas: a case-controlled study.

PubMed

Karimian, Farid; Zarei-Ghanavati, Siamak; A, Baradaran-Rafii; Jadidi, Khosrow; Lotfi-Kian, Alireza

2011-06-01

To evaluate the microbiological characteristics of eyelid margin flora in chronic blepharitis in mustard gas-exposed individuals and compare the results with those in age- and sex-matched unexposed people. In this comparative case series, 289 patients with ocular manifestations of mustard gas exposure (case) were evaluated for signs of chronic blepharitis. Additionally, microbiological evaluation of eyelid margins was conducted in these patients and compared with results of 100 unexposed patients with chronic blepharitis (control). One-hundred fifty (52.0%) of 289 mustard gas casualties had signs of chronic blepharitis. Microbiological evaluation revealed higher isolation rates of Staphylococcus epidermidis (78%) and Staphylococcus aureus (57%) in the case in comparison to control group (P < 0.01). Moreover, S. aureus isolated from the cases exhibited greater resistance to common antibiotics compared with control group. Fungi were isolated more frequent in the case compared with controls (30% vs. 4%, P < 0.01), with Cladosporium and Candida species being most common in the case group. Exposure to mustard gas seems to alter the microbiological flora of the eyelid margin. Staphylococcus spp., including antibiotic-resistant strains, and fungi were more frequently isolated in these patients. The relationship between microbial culture results and the severity of ocular surface manifestations in mustard gas-injured cases warrant further investigation.

TADPOLE satellite. [low cost synchronous orbit satellite to evaluate small mercury bombardment ion thruster applications

NASA Technical Reports Server (NTRS)

1974-01-01

A low cost synchronous orbit satellite to evaluate small mercury bombardment ion thruster applications is described. The ion thrusters provide the satellite with precise north-south and east-west stationkeeping capabilities. In addition, the thrusters are used to unload the reaction wheels used for attitude control and for other purposes described in the report. The proposed satellite is named TADPOLE. (Technology Application Demonstration Program of Low Energy).

Divergent patterns of abundance and age-class structure of headwater stream tadpoles in burned and unburned watersheds

Treesearch

Blake R. Hossack; Paul Stephen Corn; Daniel B. Fagre

2006-01-01

Wildfire is a potential threat to many species with narrow environmental tolerances like the Rocky Mountain tailed frog (Ascaphus montanus Mittleman and Myers, 1949), which inhabits a region where the frequency and intensity of wildfires are expected to increase. We compared pre- and post-fire counts of tadpoles in eight streams in northwestern...

The synthetic gestagen levonorgestrel directly affects gene expression in thyroid and pituitary glands of Xenopus laevis tadpoles.

PubMed

Lorenz, Claudia; Opitz, Robert; Trubiroha, Achim; Lutz, Ilka; Zikova, Andrea; Kloas, Werner

2016-08-01

The synthetic gestagen levonorgestrel (LNG) was previously shown to perturb thyroid hormone-dependent metamorphosis in Xenopus laevis. However, so far the mechanisms underlying the anti-metamorphic effects of LNG remained unknown. Therefore, a series of in vivo and ex vivo experiments was performed to identify potential target sites of LNG action along the pituitary-thyroid axis of X. laevis tadpoles. Prometamorphic tadpoles were treated in vivo with LNG (0.01-10nM) for 72h and brain-pituitary and thyroid tissue was analyzed for marker gene expression. While no treatment-related changes were observed in brain-pituitary tissue, LNG treatment readily affected thyroidal gene expression in tadpoles including decreased slc5a5 and iyd mRNA expression and a strong induction of dio2 and dio3 expression. When using an ex vivo organ explant culture approach, direct effects of LNG on both pituitary and thyroid gland gene expression were detecTable Specifically, treatment of pituitary explants with 10nM LNG strongly stimulated dio2 expression and concurrently suppressed tshb expression. In thyroid glands, ex vivo LNG treatment induced dio2 and dio3 mRNA expression in a thyrotropin-independent manner. When thyroid explants were cultured in thyrotropin-containing media, LNG caused similar gene expression changes as seen after 72h in vivo treatment including a very strong repression of thyrotropin-induced slc5a5 expression. Concerning the anti-thyroidal activity of LNG as seen under in vivo conditions, our ex vivo data provide clear evidence that LNG directly affects expression of genes important for thyroidal iodide handling as well as genes involved in negative feedback regulation of pituitary tshb expression. Copyright © 2016 Elsevier B.V. All rights reserved.

How sensitive are temperate tadpoles to climate change? The use of thermal physiology and niche model tools to assess vulnerability.

PubMed

Perotti, María Gabriela; Bonino, Marcelo Fabián; Ferraro, Daiana; Cruz, Félix Benjamín

2018-04-01

Ectotherms are vulnerable to climate change, given their dependence on temperature, and amphibians are particularly interesting because of their complex life cycle. Tadpoles may regulate their body temperature by using suitable thermal microhabitats. Thus, their physiological responses are the result of adjustment to the local thermal limits experienced in their ponds. We studied three anuran tadpole species present in Argentina and Chile: Pleurodema thaul and Pleurodema bufoninum that are seasonal and have broad geographic ranges, and Batrachyla taeniata, a geographically restricted species with overwintering tadpoles. Species with restricted distribution are more susceptible to climate change than species with broader distribution that may cope with potential climatic changes in the environments in which they occur. We aim to test whether these species can buffer the potential effects of climate warming. We used ecological niche models and the outcomes of their thermal attributes (critical thermal limits, optimal temperature, and locomotor performance breadth) as empirical evidence of their capacity. We found that Pleurodema species show broader performance curves, related to their occurrence, while the geographically restricted B. taeniata shows a narrower thermal breadth, but is faster in warmer conditions. The modeled distributions and empirical physiological results suggest no severe threats for these three anurans. However, the risk level is increasing and a retraction of their distribution range might be possible for Pleurodema species, and some local population extinctions may happen, particularly for the narrowly distributed B. taeniata. Copyright © 2018 Elsevier GmbH. All rights reserved.

Effects of hydroperiod duration on survival, developmental rate, and size at metamorphosis in boreal chorus frog tadpoles (Pseudacris maculata)

USGS Publications Warehouse

Amburgey, Staci; Funk, W. Chris; Murphy, Melanie; Muths, Erin

2012-01-01

Understanding the relationship between climate-driven habitat conditions and survival is key to preserving biodiversity in the face of rapid climate change. Hydroperiod—the length of time water is in a wetland—is a critical limiting habitat variable for amphibians as larvae must metamorphose before ponds dry. Changes in precipitation and temperature patterns are affecting hydroperiod globally, but the impact of these changes on amphibian persistence is poorly understood. We studied the responses of Boreal Chorus Frog (Pseudacris maculata) tadpoles to simulated hydroperiods (i.e., water level reductions) in the laboratory using individuals collected from ponds spanning a range of natural hydroperiods (Colorado Front Range, USA). To assess the effects of experimental hydroperiod reduction, we measured mortality, time to metamorphosis, and size at metamorphosis. We found that tadpoles grew at rates reflecting the hydroperiods of their native ponds, regardless of experimental treatment. Tadpoles from permanent ponds metamorphosed faster than those from ephemeral ponds across all experimental treatments, a pattern which may represent a predation selection gradient or countergradient variation in developmental rates. Size at metamorphosis did not vary across experimental treatments. Mortality was low overall but varied with pond of origin. Our results suggest that adaptation to local hydroperiod and/or predation and temperature conditions is important in P. maculata. Moreover, the lack of a plastic response to reduced hydroperiods suggests that P. maculata may not be able to metamorphose quickly enough to escape drying ponds. These results have important implications for amphibian persistence in ponds predicted to dry more quickly due to rapid climate change.

The horizontal brain slice preparation: a novel approach for visualizing and recording from all layers of the tadpole tectum.

PubMed

Hamodi, Ali S; Pratt, Kara G

2015-01-01

The Xenopus tadpole optic tectum is a multisensory processing center that receives direct visual input as well as nonvisual mechanosensory input. The tectal neurons that comprise the optic tectum are organized into layers. These neurons project their dendrites laterally into the neuropil where visual inputs target the distal region of the dendrite and nonvisual inputs target the proximal region of the same dendrite. The Xenopus tadpole tectum is a popular model to study the development of sensory circuits. However, whole cell patch-clamp electrophysiological studies of the tadpole tectum (using the whole brain or in vivo preparations) have focused solely on the deep-layer tectal neurons because only neurons of the deep layer are visible and accessible for whole cell electrophysiological recordings. As a result, whereas the development and plasticity of these deep-layer neurons has been well-studied, essentially nothing has been reported about the electrophysiology of neurons residing beyond this layer. Hence, there exists a large gap in our understanding about the functional development of the amphibian tectum as a whole. To remedy this, we developed a novel isolated brain preparation that allows visualizing and recording from all layers of the tectum. We refer to this preparation as the "horizontal brain slice preparation." Here, we describe the preparation method and illustrate how it can be used to characterize the electrophysiology of neurons across all of the layers of the tectum as well as the spatial pattern of synaptic input from the different sensory modalities. Copyright © 2015 the American Physiological Society.

Peribronchiolar fibrosis in lungs of cats chronically exposed to diesel exhaust

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hyde, D.M.; Plopper, C.G.; Weir, A.J.

This study reports the quantitative changes in the pulmonary proximal acinar region following chronic exposure to diesel exhaust and following an additional 6 months in clean air. Cats (13 months of age) from a minimum disease colony were exposed to clean air (eight cats for 27 months and nine cats for 33 months), diesel exhaust for 8 hours/day, 7 days/week (nine cats for 27 months), or diesel exhaust for 27 months followed by 6 months in clean air (10 cats). Morphologic and morphometric evaluation using light microscopy and scanning and transmission electron microscopy revealed two major exposure-related lesions in proximalmore » acinar regions of lungs of cats: peribronchiolar fibrosis associated with significant increases in lymphocytes, fibroblasts, and interstitial macrophages containing diesel particulate-like inclusions and bronchiolar epithelial metaplasia associated with the presence of ciliated and basal cells and alveolar macrophages containing diesel particulate-like inclusions. Peribronchiolar fibrosis was greater at the end of the 6 months in clean air following exposure, whereas the bronchiolar epithelial metaplasia was most severe at the end of exposure. Following an additional 6 months in clean air the epithelium more closely resembled the control epithelial cell population. The labeling index of terminal bronchiolar epithelium was significantly increased at the end of exposure but was not significantly different from controls or exposed cats following an additional 6 months in clean air. The ultrastructural appearance of epithelial cells remained relatively unchanged following diesel exhaust exposure with the exception of diesel particulate-like inclusions.« less

The tadpole of Scinax melanodactylus (Lourenço, Luna & Pombal Jr, 2014) (Amphibia, Anura, Hylidae).

PubMed

Abreu, Rafael Oliveira De; Napoli, Marcelo Felgueiras; Trevisan, Camila Costa; Camardelli, Milena; Dória, Thais Andrade Ferreira; Silva, Lucas Menezes

2015-07-06

Scinax melanodactylus is a small treefrog distributed within the Tropical Atlantic morphoclimatic domain (see Ab'Sáber 1977 for South American morphoclimatic domains), from northern Espírito Santo state to Sergipe state in Brazil (Lourenço et al. 2014). The species is usually found inhabiting herbaceous and shrubby xerophytic vegetation (e.g. terrestrial tank-bromeliads) from sandy plains of beach ridges known in Brazil as Restingas (see Rocha et al. 2007 for a Restinga definition), and also the edge of forest areas with temporary ponds and/or permanent lakes and streams near these environments (Bastazini et al. 2007, as Scinax agilis; Lourenço et al. 2014). Scinax melanodactylus is currently placed in the S. catharinae species group (Lourenço et al. 2014), which in turn is included in the S. catharinae clade (sensu Faivovich et al. 2005). The S. catharinae clade is currently comprised of 46 species, 33 placed in the catharinae group and 13 in the perpusillus group (Faivovich et al. 2010, Silva & Alves-da-Silva 2011, Lourenço et al. 2014, Frost 2015). From these, 32 species have tadpoles with external morphology and oral disc formerly described. Here, we describe the external morphology, oral disc and color patterns of the previously unknown tadpole of S. melanodactylus.

Ultrastructural nasal pathology in children chronically and sequentially exposed to air pollutants.

PubMed

Calderón-Garcidueñas, L; Valencia-Salazar, G; Rodríguez-Alcaraz, A; Gambling, T M; García, R; Osnaya, N; Villarreal-Calderón, A; Devlin, R B; Carson, J L

2001-02-01

Southwest Metropolitan Mexico City (SWMMC) children are repeatedly exposed to a complex mixture of air pollutants, including ozone, particulate matter, and aldehydes. Nasal biopsies taken from these children exhibit a wide range of histopathologic alterations: marked changes in ciliated and goblet cell populations, basal cell hyperplasia, squamous metaplasia, and mild dysplasias. We studied the ultrastructural features of 15 nasal biopsies obtained from clinically healthy children 4 to 15 yr of age, growing up in SWMMC. The results were compared with nasal biopsies from 11 children growing up in Veracruz and exposed to low pollutant levels. Ultrathin sections of nasal biopsies revealed an unremarkable mucociliary epithelium in control children, whereas SWMMC children showed an epithelium comprised of variable numbers of basal, ciliated, goblet, and squamous metaplastic as well as intermediate cells. Nascent ciliated cells, as evidenced by the presence of migratory kinetosomes, were common, as were ciliary abnormalities, including absent central microtubules, supernumerary central and peripheral tubules, ciliary microtubular discontinuities, and compound cilia. Dyskinesia associated with these abnormal cilia was suggested by the altered orientation of the central microtubules in closely adjacent cilia. A transudate was evident between epithelial cells, suggesting potential deficiencies in epithelial junction integrity. Particulate matter was present in heterolysosomal bodies in epithelial cells and it was also deposited in intercellular spaces. The severe structural alteration of the nasal epithelium together with the prominent acquired ciliary defects are likely the result of chronic airway injury in which ozone, particulate matter, and aldehydes are thought to play a crucial role. The nasal epithelium in SWMMC children is fundamentally disordered, and their mucociliary defense mechanisms are no longer intact. A compromised nasal epithelium has less ability to

Branchial and renal pathology in the fish exposed chronically to methoxy ethyl mercuric chloride

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gill, T.S.; Pant, J.C.; Tewari, H.

1988-08-01

Pathological manifestations causally related to pesticide poisoning have been described in both surficial and internal tissues of the fishes. Among the various organomercurials are phenyl mercuric acetate, methyl mercuric dicyanidiamide, methoxy ethyl mercuric chloride, methoxy ethyl mercuric silicate etc. Of these, the methoxy ethyl mercuric chloride (MEMC) is used in agriculture as an antifungal seed dressing, and its toxicity is primarily manifest in the Hg/sup 2 +/ ion. This report describes pathogenesis of branchial and renal lesions in the common freshwater fish, Puntius conchonius exposed chronically to sublethal levels of MEMC. Prior to this, alterations in the peripheral blood andmore » metabolite levels in response to experimental MEMC poisoning have been demonstrated in this species.« less

The Effects of Eucheuma cottonii on Signaling Pathway Inducing Mucin Synthesis in Rat Lungs Chronically Exposed to Particulate Matter 10 (PM10) Coal Dust

PubMed Central

Kania, Nia; Mayangsari, Elly; Tony, Frans; Wahyuni, Endang Sri; Widodo, M. Aris

2013-01-01

This study was aimed at investigating the effects of Eucheuma cottonii (EC) in oxidative stress and the signaling for mucin synthesis in rat lungs chronically exposed to coal dust. Coal dust with concomitant oral administration of ethanolic extract of EC at doses of 150 (EC150) or 300 mg/kg BW (EC300) compared to exposed to PM10 coal dust at doses of 6.25 (CD6.25), 12.5 (CD12.5), or 25 mg/m3 (CD25) (an hour daily for 6 months) and nonexposure group (control). The malondialdehyde (MDA), epidermal growth factor (EGF), transforming growth factor (TGF)-α, epidermal growth factor receptor (EGFR), and MUC5AC levels were determined in the lung. The administration of EC300 significantly (p < 0.05) reduced the MDA levels in groups exposed to all doses of coal dust compared to the respective coal dust-exposed nonsupplemented groups. Although not statistically significant,EC reduced the EGF levels and EGFR expressions in CD12.5 and CD25 groups and decreased the TGF-α, level and MUC5AC expression in CD25 group compared to the respective coal dust-exposed nonsupplemented groups. EC was able to decrease oxidative stress and was also able to decrease signaling for mucin synthesis, at least a part, via reducing the ligand in chronic coal dust exposure. PMID:24228027

Selenite restores Pax6 expression in neuronal cells of chronically arsenic-exposed Golden Syrian hamsters.

PubMed

Aguirre-Vázquez, Alain; Sampayo-Reyes, Adriana; González-Escalante, Laura; Hernández, Alba; Marcos, Ricard; Castorena-Torres, Fabiola; Lozano-Garza, Gerardo; Taméz-Guerra, Reyes; de León, Mario Bermúdez

2017-01-01

Arsenic is a worldwide environmental pollutant that generates public health concerns. Various types of cancers and other diseases, including neurological disorders, have been associated with human consumption of arsenic in drinking water. At the molecular level, arsenic and its metabolites have the capacity to provoke genome instability, causing altered expression of genes. One such target of arsenic is the Pax6 gene that encodes a transcription factor in neuronal cells. The aim of this study was to evaluate the effect of two antioxidants, α-tocopheryl succinate (α-TOS) and sodium selenite, on Pax6 gene expression levels in the forebrain and cerebellum of Golden Syrian hamsters chronically exposed to arsenic in drinking water. Animals were divided into six groups. Using quantitative real-time reverse transcriptase (RT)-PCR analysis, we confirmed that arsenic downregulates Pax6 expression in nervous tissues by 53 ± 21% and 32 ± 7% in the forebrain and cerebellum, respectively. In the presence of arsenic, treatment with α-TOS did not modify Pax6 expression in nervous tissues; however, sodium selenite completely restored Pax6 expression in the arsenic-exposed hamster forebrain, but not the cerebellum. Although our results suggest the use of selenite to restore the expression of a neuronal gene in arsenic-exposed animals, its use and efficacy in the human population require further studies.

Lung radiology and pulmonary function of children chronically exposed to air pollution.

PubMed

Calderón-Garcidueñas, Lilian; Mora-Tiscareño, Antonieta; Fordham, Lynn A; Chung, Charles J; Valencia-Salazar, Gildardo; Flores-Gómez, Silvia; Solt, Anna C; Gomez-del Campo, Alberto; Jardón-Torres, Ricardo; Henríquez-Roldán, Carlos; Hazucha, Milan J; Reed, William

2006-09-01

We analyzed the chest radiographs (CXRs) of 249 clinically healthy children, 230 from southwest Mexico City and 19 from Tlaxcala. In contrast to children from Tlaxcala, children from southwest Mexico City were chronically exposed to ozone levels exceeding the U.S. National Ambient Air Quality Standards for an average of 4.7 hr/day and to concentrations of particulate matter (PM) with aerodynamic diameters chronic pulmonary disease later in life.

Inverse Effects on Growth and Development Rates by Means of Endocrine Disruptors in African Clawed Frog Tadpoles ("Xenopus Laevis")

ERIC Educational Resources Information Center

Hackney, Zachary Carl

2007-01-01

Previous work on fish, frogs, and salamanders, showed the ability for estrogen (EE2) and anthropogenic endocrine disruptors to skew sex ratios and cause hermaphrodism. This study addressed the effects of estrogens on growth and development rates of African clawed frog tadpoles ("Xenopus laevis") during their gender determination stages. The…

Effect of corticosterone on larval growth, antipredator behaviour and metamorphosis of Hylarana indica.

PubMed

Kulkarni, P S; Gramapurohit, N P

2017-09-15

Corticosterone (CORT), a principal glucocorticoid in amphibians, is known to regulate diverse physiological processes including growth and metamorphosis of anuran tadpoles. Environmental stressors activate the neuroendocrine stress axis (hypothalamus-pituitary-interrenal axis, HPI) leading to an acute increase in CORT, which in turn, helps in coping with particular stress. However, chronic increase in CORT can negatively affect other physiological processes such as growth and metamorphosis. Herein, we studied the effect of exogenous CORT on larval growth, antipredator behaviour and metamorphic traits of Hylarana indica. Embryonic exposure to 5 or 20μg/L CORT did not affect their development, hatching duration as well as larval growth and metamorphosis. Exposure of tadpoles to 10 or 20μg/L CORT throughout larval development caused slower growth and development leading to increased body mass at stage 37. However, body and tail morphology of tadpoles was not affected. Interestingly, larval exposure to 5, 10 or 20μg/L CORT enhanced their antipredator response against kairomones in a concentration-dependent manner. Further, larval exposure to increasing concentrations of CORT resulted in the emergence of heavier froglets at 10 and 20μg/L while, delaying metamorphosis at all concentrations. Interestingly, the heavier froglets had shorter hindlimbs and consequently shorter jump distances. Tadpoles exposed to 20μg/L CORT during early, mid or late larval stages grew and developed slowly but tadpole morphology was not altered. Interestingly, exposure during early or mid-larval stages resulted in an enhanced antipredator response. These individuals metamorphosed later but at higher body mass while SVL was unaffected. Copyright © 2016 Elsevier Inc. All rights reserved.

Urinary Trivalent Methylated Arsenic Species in a Population Chronically Exposed to Inorganic Arsenic

PubMed Central

Valenzuela, Olga L.; Borja-Aburto, Victor H.; Garcia-Vargas, Gonzalo G.; Cruz-Gonzalez, Martha B.; Garcia-Montalvo, Eliud A.; Calderon-Aranda, Emma S.; Del Razo, Luz M.

2005-01-01

Chronic exposure to inorganic arsenic (iAs) has been associated with increased risk of various forms of cancer and of noncancerous diseases. Metabolic conversions of iAs that yield highly toxic and genotoxic methylarsonite (MAsIII) and dimethylarsinite (DMAsIII) may play a significant role in determining the extent and character of toxic and cancer-promoting effects of iAs exposure. In this study we examined the relationship between urinary profiles of MAsIII and DMAsIII and skin lesion markers of iAs toxicity in individuals exposed to iAs in drinking water. The study subjects were recruited among the residents of an endemic region of central Mexico. Drinking-water reservoirs in this region are heavily contaminated with iAs. Previous studies carried out in the local populations have found an increased incidence of pathologies, primarily skin lesions, that are characteristic of arseniasis. The goal of this study was to investigate the urinary profiles for the trivalent and pentavalent As metabolites in both high- and low-iAs–exposed subjects. Notably, methylated trivalent arsenicals were detected in 98% of analyzed urine samples. On average, the major metabolite, DMAsIII, represented 49% of total urinary As, followed by DMAsV (23.7%), iAsV (8.6%), iAsIII (8.5%), MAsIII (7.4%), and MAsV (2.8%). More important, the average MAsIII concentration was significantly higher in the urine of exposed individuals with skin lesions compared with those who drank iAs-contaminated water but had no skin lesions. These data suggest that urinary levels of MAsIII, the most toxic species among identified metabolites of iAs, may serve as an indicator to identify individuals with increased susceptibility to toxic and cancer-promoting effects of arseniasis. PMID:15743710

Virtual dissection of Thoropa miliaris tadpole using phase-contrast synchrotron microtomography

NASA Astrophysics Data System (ADS)

Fidalgo, G.; Colaço, M. V.; Nogueira, L. P.; Braz, D.; Silva, H. R.; Colaço, G.; Barroso, R. C.

2018-05-01

In this work, in-line phase-contrast synchrotron microtomography was used in order to study the external and internal morphology of Thoropa miliaris tadpoles. Whole-specimens of T. miliaris in larval stages of development 28, 37 and 42, collected in the municipality of Mangaratiba (Rio de Janeiro, Brazil) were used for the study. The samples were scanned in microtomography beamline (IMX) at the Brazilian Synchrotron Light Laboratory (LNLS). The phase-contrast technique allowed us to obtain high quality images which made possible the structures segmentation on the rendered volume by the Avizo graphic image editing software. The combination of high quality images and segmentation process provides adequate visualization of different organs and soft (liver, notochord, brain, crystalline, cartilages) and hard (elements of the bone skeleton) tissues.

COMPARISON OF PRESSURIZED LIQUID EXTRACTION AND MATRIX SOLID PHASE DISPERSION FOR THE MEASUREMENT OF SEMI-VOLATILE ORGANIC COMPOUND ACCUMULATION IN TADPOLES

EPA Science Inventory

Analytical methods capable of trace measurement of semi-volatile organic compounds (SOCs) are necessary to assess the exposure of tadpoles to contaminants as a result of long-range and regional atmospheric transport and deposition. The following study compares the results of two ...

Impaired lung function in individuals chronically exposed to biomass combustion.

PubMed

da Silva, Luiz Fernando Ferraz; Saldiva, Silvia Regina Dias Médici; Saldiva, Paulo Hilário Nascimento; Dolhnikoff, Marisa

2012-01-01

The use of biomass for cooking and heating is considered an important factor associated with respiratory diseases. However, few studies evaluate the amount of particulate matter less than 2.5 μm in diameter (PM2.5), symptoms and lung function in the same population. To evaluate the respiratory effects of biomass combustion and compare the results with those of individuals from the same community in Brazil using liquefied petroleum gas (Gas). 1402 individuals in 260 residences were divided into three groups according to exposure (Gas, Indoor-Biomass, Outside-Biomass). Respiratory symptoms were assessed using questionnaires. Reflectance of paper filters was used to assess particulate matter exposure. In 48 residences the amount of PM2.5 was also quantified. Pulmonary function tests were performed in 120 individuals. Reflectance index correlated directly with PM2.5 (r=0.92) and was used to estimate exposure (ePM2.5). There was a significant increase in ePM2.5 in Indoor-Biomass and Outside-Biomass, compared to Gas. There was a significantly increased odds ratio (OR) for cough, wheezing and dyspnea in adults exposed to Indoor-Biomass (OR=2.93, 2.33, 2.59, respectively) and Outside-Biomass (OR=1.78, 1.78, 1.80, respectively) compared to Gas. Pulmonary function tests revealed both Non-Smoker-Biomass and Smoker-Gas individuals to have decreased %predicted-forced expiratory volume in the first second (FEV1) and FEV1/forced vital capacity (FVC) as compared to Non-Smoker-Gas. Pulmonary function tests data was inversely correlated with duration and ePM2.5. The prevalence of airway obstruction was 20% in both Non-Smoker-Biomass and Smoker-Gas subjects. Chronic exposure to biomass combustion is associated with increased prevalence of respiratory symptoms, reduced lung function and development of chronic obstructive pulmonary disease. These effects are associated with the duration and magnitude of exposure and are exacerbated by tobacco smoke. Copyright © 2011 Elsevier Inc. All

Mediation of cholino-piperine like receptors by extracts of Piper nigrum induces melanin dispersion in Rana tigerina tadpole melanophores.

PubMed

Sajid, Mohammed; Ali, Sharique A

2011-08-01

The present study was carried out to determine the effects of lyophilized dried fruit extracts of Piper nigrum and pure piperine on the tadpole melanophores of frog Rana tigerina which offer excellent in vitro opportunities for studying the effects of pharmacological and pharmaceutical agents. The nature of specific cellular receptors present on the neuro-melanophore junction and their involvement in pigmentary responses has been explored. Effects of lyophilized extracts of P. nigrum and pure piperine were studied on the isolated tail melanophores of tadpoles of the frog R. tigerina as per the modified method. The extract of P. nigrum and its active ingredient piperine caused significant melanin dispersal responses leading to darkening of the tail melanophores, which were completely antagonized by atropine and hyoscine. These per se melanin dispersal effects were also found to be markedly potentiated by neostigmine an anticholinesterase agent. It appears that the melanin dispersal effects of the extracts of P. nigrum and pure piperine leading to skin darkening are mediated by cholinergic muscarinic or piperine-like receptors having similar properties.

Description of the tadpoles of three rare species of megophryid frogs (Amphibia: Anura: Megophryidae) from Gunung Mulu, Sarawak, Malaysia.

PubMed

Oberhummer, Evelyne; Barten, Catherin; Schweizer, Manuel; Das, Indraneil; Haas, Alexander; Hertwig, Stefan T

2014-07-09

The megophryid frogs Leptobrachella brevicrus, Leptolalax dringi and Megophrys dringi are species exclusively known  from highly localised areas in isolated mountain ranges on Borneo. The tadpoles and adults in this study were collected at the shared type locality for the three species in Gunung Mulu National Park, Sarawak, Malaysia (Borneo). The species identities of larvae were determined via comparison to syntopic adults using DNA barcoding techniques based on partial 16S rRNA mitochondrial gene sequences. The genetic data supported the status of the three taxa as valid species. Descriptions of colouration in life and after preservation, external morphological features, morphometric measurements and ecological notes in comparison to congeneric species are supplied. The tadpoles of L. brevicrus and L. dringi show similar adaptations to a fossorial lifestyle. These include an elongated, vermiform body, a relatively long tail and small eyes. Both were found in the gravel beds of a small mountain stream. In contrast, the larvae of M. dringi are adapted to occupying and feeding at the surface of pools within the stream. 

Disturbing Effects of Chronic Low-dose 4-Nonylphenol exposing on Gonadal Weight and Reproductive Outcome over One-generation

PubMed Central

Cha, Sunyeong; Baek, Jeong Won; Ji, Hye Jin; Choi, Jun Hee; Kim, Chaelim; Lee, Min Young; Hwang, Yeon Jeong; Yang, Eunhyeok; Lee, Sung-Ho; Jung, Hyo-il; Cheon, Yong-Pil

2017-01-01

ABSTRACT 4-Nonylphenol (NP) is a surfactant that is a well-known and widespread estrogenic endocrine disrupting chemical (EDC). Although it has been known that the affinity of NP to ERs is low, it has been suggested that low-dose NP has toxicity. In the present study, the endocrine disrupting effects on reproduction, and the weight of gonads, epididymis, and uterus were evaluated with the chronic lower-dose NP exposing. This study was designed by following the OECD test guideline 443 and subjected to a complete necropsy. In male, NP had an effect on the weight of the testis and epididymis in both F0 and F1. In females, NP decreased the weight of ovary and uterus in F0 but not in pre-pubertal F1 pubs. Fertility of male and female in F0 or F1 was no related with NP administration. The number of caudal-epididymal sperm by body weight (BW) was not different between groups in both F0 and F1. Besides, the difference of the sperm number between generations was not detected. The number of ovulated oocytes was similar between groups in F0, but significantly decreased in NP 50 group of F1. The litter size and sex ratios of offspring in F1 and F2 were not different. The accumulated mating rate and gestation period were not affected by the NP administration. Those results shows that chronic lower-dose NP administration has an effect of endocrine disruptor on the weight of gonads and epididymis of F0 and F1 but not in reproduction. Based on the results, it is suggested that chronic lower-dose NP exposing causes endocrine disruption in the weight of gonad and epididymis but not in the reproductive ability of next generations. PMID:28785733

Examining multiple sublethal contaminants on the gray treefrog (Hyla versicolor): effects of an insecticide, herbicide, and fertilizer

USGS Publications Warehouse

Boone, M.D.; Bridges-Britton, C. M.

2006-01-01

We examined the single and interactive effects of an insecticide, an herbicide, and a fertilizer on gray treefrog (Hyla versicolor) tadpoles. Tadpoles were reared in mesocosms from hatching through metamorphosis and were exposed to the presence or absence of as many as three contaminants. Tadpoles did not appear to be more susceptible to single versus multiple contaminants, which may result from positive changes in food resources that compensate for the effects of other contaminants. ?? 2006 SETAC.

Costs and limits of dosage response to predation risk: to what extent can tadpoles invest in anti-predator morphology?

PubMed

Teplitsky, Céline; Plénet, Sandrine; Joly, Pierre

2005-09-01

Inducible defences have long been considered as a polyphenism opposing defended and undefended morphs. However, in nature, preys are exposed to various levels of predation risk and scale their investment in defence to actual predation risk. Still, among the traits that are involved in the defence, some are specific to one predator type while others act as a more generalised defence. The existence of defence costs could prevent an individual investing in all these traits simultaneously. In this study, we investigate the impact of an increasing level of predator density (stickleback, Gasterosteus aculeatus) on the expression of morphological inducible defences in tadpoles of Rana dalmatina. In this species, investment in tail length and tail muscle is a stickleback-specific response while increased tail fin depth is a more general defence. As expected, we found a relationship between investment in defence and level of risk through the responses of tail fin depth and tail length. We also found an exponential increase of defence cost, notably expressed by convex decrease of growth and developmental rates. We found a relative independence of investment in the different traits that compose the defence, revealing a high potential for fine tuning the expression of defended phenotypes with respect to local ecological conditions.

Bioaccumulation of polycyclic aromatic compounds: 2. Modeling bioaccumulation in marine organisms chronically exposed to dispersed oil.

PubMed

Baussant, T; Sanni, S; Skadsheim, A; Jonsson, G; Børseth, J F; Gaudebert, B

2001-06-01

Within the frame of a large environmental study, we report on a research program that investigated the potential for bioaccumulation and subsequent effect responses in several marine organisms exposed to chronic levels of dispersed crude oil. Body burden can be estimated from kinetic parameters (rate constants for uptake and elimination), and appropriate body burden-effect relationships may improve assessments of environmental risks or the potential for such outcomes following chronic discharges at sea. We conducted a series of experiments in a flow-through system to describe the bioaccumulation kinetics of polycyclic aromatic hydrocarbons (PAH) at low concentrations of dispersed crude oils. Mussels (Mytilus edulis) and juvenile turbot (Scophthalmus maximus) were exposed for periods ranging from 8 to 21 d. Postexposure, the organisms were kept for a period of 9 to 10 d in running seawater to study elimination processes. Rate constants of uptake (k1) and elimination (k2) of the PAHs during and following exposure were calculated using a first-order kinetic model that assumed a decrease of the substances in the environment over time. The estimated bioconcentration factor was calculated from the ratio of k1/k2. The kinetic parameters of two-, three-, and four-ring PAHs in mussel and fish are compared with estimates based on hydrophobicity alone, expressed by the octanol-water partition coefficient, Kow (partitioning theory). A combination of reduced bioavailability of PAHs from oil droplets and degradation processes of PAHs in body tissues seems to explain discrepancies between kinetic rates based on Kow and actual kinetic rates measured in fish. Mussels showed a pattern more in compliance with the partitioning theory.

COMPARATIVE TOXICITY OF DIURON ON SURVIVAL AND GROWTH OF PACIFIC TREEFROG, BULLFROG, RED-LEGGED FROG, AND AFRICAN CLAWED FROG EMBRYOS AND TADPOLES

EPA Science Inventory

The effects of the herbicide diuron on survival and growth of Pacific treefrog (Pseudacris regilla),bullfrog(Rana catesbeiana), red-legged frog(Rana aurora),and African clawed frog(Xenopus laevis)embryos and tadpoles were determined in static-renewal tests. P.regilla and X.laevis...

Lung function status of some Nigerian men and women chronically exposed to fish drying using burning firewood.

PubMed

Peters, E J; Esin, R A; Immananagha, K K; Siziya, S; Osim, E E

1999-05-01

To determine the lung function status of some Nigerian men and women chronically exposed to fish drying using burning firewood. Case control study. Ibaka, Utaewa and Ikanga fishing settlements. 183 males and 192 females engaged in fishing, aged 20 to 45 years who have been exposed for a minimum of five years as cases. The control group comprised sex matched male (142) and female (152) Nigerians from the same area who were not exposed to any known air pollutant. Lung function indices: FVC, FEV1, FEV1% and PEFR. Lung function indices were significantly lower in men engaged in fishing than in their controls: FVC [mean (SD): 2.98 (0.20) vs 3.52 (0.29), p < 0.001]; FEV1 [2.08 (0.18) vs 2.82 (0.25), p < 0.001]; FEV1% [69.8 (3.1) vs 80.2 (6.7), p < 0.001]; and PEFR [335 (22) vs 592 (99), p < 0.001], respectively. Similarly, lung function indices were lower in females in the fishing industry than in their controls; FVC [2.42 (0.17) vs 3.02 (0.24), p < 0.001]; FEV1 [1.70 (0.19) vs 2.55 (0.21), p < 0.001]; FEV1% [72.9 (3.2) vs 84.4 (6.7), p < 0.001]; and PEFR [298 (22) vs 418 (34), p < 0.001]. All the lung function indices (except FEV1%) of the fishermen and women declined significantly (p < 0.001) with their duration of exposure. The results showed a predominantly mixed pattern (restrictive and obstructive) of respiratory defect. There were higher prevalences of respiratory and other symptoms among the cases than the controls. The respiratory symptoms included cough with sputum, chest pain, dyspnoea catarrh and sneezing and unproductive cough. Other symptoms were eye and skin irritation, internal heat and headache. Chronic exposure to fish drying using burning firewood can impair lung function and cause respiratory and other symptoms.

Where have all the tadpoles gone? Individual genetic tracking of amphibian larvae until adulthood

PubMed Central

RINGLER, EVA; MANGIONE, ROSANNA; RINGLER, MAX

2015-01-01

Reliably marking larvae and reidentifying them after metamorphosis is a challenge that has hampered studies on recruitment, dispersal, migration and survivorship of amphibians for a long time, as conventional tags are not reliably retained through metamorphosis. Molecular methods allow unique genetic fingerprints to be established for individuals. Although microsatellite markers have successfully been applied in mark–recapture studies on several animal species, they have never been previously used in amphibians to follow individuals across different life cycle stages. Here, we evaluate microsatellites for genetic across-stages mark–recapture studies in amphibians and test the suitability of available software packages for genotype matching. We sampled tadpoles of the dendrobatid frog Allobates femoralis, which we introduced on a river island in the Nature Reserve ‘Les Nouragues’ in French Guiana. In two subsequent recapture sessions, we searched for surviving juveniles and adults, respectively. All individuals were genotyped at 14 highly variable microsatellite loci, which yielded unique genetic fingerprints for all individuals. We found large differences in the identification success of the programs tested. The pairwise-relatedness-based approach, conducted with the programs kingroup or ML-Relate, performed best with our data set. Matching ventral patterns of juveniles and adult individuals acted as a control for the reliability of the genetic identification. Our results demonstrate that microsatellite markers are a highly powerful tool for studying amphibian populations on an individual basis. The ability to individually track amphibian tadpoles throughout metamorphosis until adulthood will be of substantial value for future studies on amphibian population ecology and evolution. PMID:25388775

Transmission probabilities of mouse parvovirus 1 to sentinel mice chronically exposed to serial dilutions of contaminated bedding.

PubMed

Besselsen, David G; Myers, Erin L; Franklin, Craig L; Korte, Scott W; Wagner, April M; Henderson, Kenneth S; Weigler, Benjamin J

2008-04-01

Intermittent serodetection of mouse parvovirus (MPV) infections in animal facilities occurs frequently when soiled bedding sentinel mouse monitoring systems are used. We evaluated induction of seroconversion in naïve single-caged weanling ICR mice (n = 10 per group) maintained on 5-fold serially diluted contaminated bedding obtained from SCID mice persistently shedding MPV1e. Soiled bedding from the infected SCID mice was collected, diluted, and redistributed weekly to cages housing ICR mice to represent chronic exposure to MPV at varying prevalence in a research colony. Sera was collected every other week for 12 wk and evaluated for reactivity to MPV nonstructural and capsid antigens by multiplex fluorescent immunoassay. Mice were euthanized after seroconversion, and DNA extracted from lymph node and spleen was evaluated by quantitative PCR. Cumulative incidence of MPV infection for each of the 7 soiled bedding dilution groups (range, 1:5 to 1:78125 [v/v]) was 100%, 100%, 90%, 20%, 70%, 60%, and 20%, respectively. Most seropositive mice (78%) converted within the first 2 to 3 wk of soiled bedding exposure, correlating to viral exposure when mice were 4 to 7 wk of age. Viral DNA was detected in lymphoid tissues collected from all mice that were seropositive to VP2 capsid antigen, whereas viral DNA was not detected in lymphoid tissue of seronegative mice. These data indicate seroconversion occurs consistently in young mice exposed to high doses of virus equivalent to fecal MPV loads observed in acutely infected mice, whereas seroconversion is inconsistent in mice chronically exposed to lower doses of virus.

Could high salinity be used to control bullfrogs in small ponds?

USGS Publications Warehouse

Ward, David L.; Finch, Colton; Blasius, Heidi

2015-01-01

We examined survival of bullfrog (Rana catesbeiana) eggs and tadpoles at 3 ppt and 6 ppt salinity in the laboratory to determine if low-level salinity could be used to eradicate bullfrogs from small ponds that contain native fishes. Bullfrog eggs and tadpoles <10 days old experienced 100% mortality when held at 6 ppt salinity for 10 days. Bullfrog tadpoles 10–15 days old experienced significantly reduced survival when exposed to salinity of 6 ppt for 10 days. Older bullfrog tadpoles (>9 months old) appeared unaffected by 14 days of 6 ppt salinity. Salinity of 3 ppt did not impact survival of bullfrog tadpole eggs or tadpoles at any of the life stages we tested. Adding salt to ponds in the early spring to increase salinity to 6 ppt may be a cost effective way to eradicate bullfrogs from small ponds without harming native fishes.

Signs and symptoms of mercury-exposed gold miners.

PubMed

Bose-O'Reilly, Stephan; Bernaudat, Ludovic; Siebert, Uwe; Roider, Gabriele; Nowak, Dennis; Drasch, Gustav

2017-03-30

Gold miners use mercury to extract gold from ore adding liquid mercury to the milled gold-containing ore. This results in a mercury-gold compound, called amalgam. Miners smelt this amalgam to obtain gold, vaporizing it and finally inhaling the toxic mercury fumes. The objective was to merge and analyze data from different projects, to identify typical signs and symptoms of chronic inorganic mercury exposure. Miners and community members from various artisanal small-scale gold mining areas had been examined (Philippines, Mongolia, Tanzania, Zimbabwe, Indonesia). Data of several health assessments were pooled. Urine, blood and hair samples were analyzed for mercury (N = 1252). Questionnaires, standardized medical examinations and neuropsychological tests were used. Participants were grouped into: Controls (N = 209), living in an exposed area (N = 408), working with mercury as panners (N = 181), working with mercury as amalgam burners (N = 454). Chi² test, linear trend test, Mann-Whitney test, Kruskal-Wallis test, correlation coefficient, Spearman's rho, and analysis of variance tests were used. An algorithm was used to define participants with chronic mercury intoxication. Mean mercury concentrations in all exposed subgroups were elevated and above threshold limits, with amalgam burners showing highest levels. Typical symptoms of chronic metallic mercury intoxication were tremor, ataxia, coordination problems, excessive salivation and metallic taste. Participants from the exposed groups showed poorer results in different neuropsychological tests in comparison to the control group. Fifty-four percent of the high-exposed group (amalgam burners) were diagnosed as being mercury-intoxicated, compared to 0% within the control group (Chi² p < 0.001). Chronic mercury intoxication, with tremor, ataxia and other neurological symptoms together with a raised body burden of mercury was clinically diagnosed in exposed people in artisanal small-scale mining

Effect of exposure to contaminated pond sediments on survival, development, and enzyme and blood biomarkers in veined treefrog (Trachycephalus typhonius) tadpoles.

PubMed

Peltzer, Paola M; Lajmanovich, Rafael C; Attademo, Andrés M; Junges, Celina M; Cabagna-Zenklusen, Mariana C; Repetti, María R; Sigrist, María E; Beldoménico, Horacio

2013-12-01

Sediments are important elements of aquatic ecosystems and in general sediments accumulate diverse toxic substances. Amphibians potentially have a greater risk of exposure to contaminants in sediments, and the test of sediments provides first lines of evidences. Sediment outdoor microcosm experiments were conducted to analyze biological endpoints (survival, development, growth, and morphological and organ malformation), enzyme activity (butyrylcholinesterase, BChE; glutathione-S-transferase, GST; and catalase, CAT) and blood biomarkers in veined treefrog Trachycephalus typhonius tadpoles, a widespread neotropical species. Hatching (stage 23) of T. thyphonius was exposed until they reached metamorphosis (stage 46). Sediment tests were performed and four different treatments were used: three ponds (LTPA, ISP, and SSP) influenced by industrial and agricultural activities and a reference treatment from a forest (RFS). Physical and chemical variables and concentration of nutrients, pesticide residues, and metals were determined. One treatment was metal-rich (LPTA) and two were nutrient-rich (ISP and SSP). Sediment treatments had no significant effect on survival; in contrast they had significant sublethal effects on T. typhonius larval development and growth rates, and affected overall size and shape at stage 38. Principally, in LPTA animals were significantly larger than in RFS, exhibiting swollen bodies, tail muscles and tail fin. In addition, metamorphs from LPTA, ISP, and SSP were smaller and showed signs of emaciation by the end of the experiment. Statistical comparisons showed that the proportions of each type of morphological abnormalities (swollen bodies and diamond shape, gut uncoiling, diverted gut, stiff tails, polydactyly, and visceral and hindlimb hemorrhaging) were significantly greater in metal- and nutrient-rich sediment treatments. Moreover, activities of BChE, GST and CAT, as well as and presence of micronuclei, immature, mitotic, anucleated

Lung inflammation biomarkers and lung function in children chronically exposed to arsenic

PubMed Central

Olivas-Calderón, Edgar; Recio-Vega, Rogelio; Gandolfi, A. Jay; Lantz, R. Clark; González-Cortes, Tania; Alba, Cesar Gonzalez-De; Froines, John R.; Espinosa-Fematt, Jorge A.

2016-01-01

Evidence suggests that exposure to arsenic in drinking water during early childhood or in utero is associated with an increase in respiratory symptoms and diseases in adulthood, however only a few studies have been carried out during those sensitive windows of exposure. Recently our group demonstrated that exposure to arsenic during early childhood or in utero was associated with impairment in the lung function in children and suggested that this adverse effect could be due to a chronic inflammatory response to the metalloid. Therefore, a cross-sectional study was designed in a cohort of children associating lung inflammatory biomarkers and lung function with urinary As levels. A total of 275 healthy children were partitioned into four study groups according with their As levels. Inflammation biomarkers were measured in sputum by ELISA and the lung function was evaluated by spirometry. Fifty eight percent of the studied children were found to have a restrictive spirometric pattern. In the two highest exposed groups, the Soluble Receptor for Advanced Glycation Endproducts (sRAGE) sputum level was significantly lower and Matrix Metalloproteinase-9 (MMP-9) concentration was higher. When the biomarkers were correlated to the urinary arsenic species, negative associations were found between dimethylarsinic (DMA), monomethylarsenic percentage (%MMA) and dimethylarsinic percentage (%DMA) with sRAGE and positive associations between %DMA with MMP-9 and with the MMP-9/Tissue Inhibitor of Metalloproteinase (TIMP-1) ratio. In conclusion, chronic arsenic exposure of children negatively correlates with sRAGE, and positively correlated with MMP-9 and MMP-9/TIMP-1 levels, and increases the frequency of an abnormal spirometric pattern. PMID:26048584

Cytogenetic damage analysis in mice chronically exposed to low-dose internal tritium beta-particle radiation.

PubMed

Roch-Lefèvre, Sandrine; Grégoire, Eric; Martin-Bodiot, Cécile; Flegal, Matthew; Fréneau, Amélie; Blimkie, Melinda; Bannister, Laura; Wyatt, Heather; Barquinero, Joan-Francesc; Roy, Laurence; Benadjaoud, Mohamed; Priest, Nick; Jourdain, Jean-René; Klokov, Dmitry

2018-06-08

The aim of this study was to carry out a comprehensive examination of potential genotoxic effects of low doses of tritium delivered chronically to mice and to compare these effects to the ones resulting from equivalent doses of gamma-irradiation. Mice were chronically exposed for one or eight months to either tritiated water (HTO) or organically bound tritium (OBT) in drinking water at concentrations of 10 kBq/L, 1 MBq/L or 20 MBq/L. Dose rates of internal β-particle resulting from such tritium treatments were calculated and matching external gamma-exposures were carried out. We measured cytogenetic damage in bone marrow and in peripheral blood lymphocytes (PBLs) and the cumulative tritium doses (0.009 - 181 mGy) were used to evaluate the dose-response of OBT in PBLs, as well as its relative biological effectiveness (RBE). Neither tritium, nor gamma exposures produced genotoxic effects in bone marrow. However, significant increases in chromosome damage rates in PBLs were found as a result of chronic OBT exposures at 1 and 20 M Bq/L, but not at 10 kBq/L. When compared to an external acute gamma-exposure ex vivo , the RBE of OBT for chromosome aberrations induction was evaluated to be significantly higher than 1 at cumulative tritium doses below 10 mGy. Although found non-existent at 10 kBq/L (the WHO limit), the genotoxic potential of low doses of tritium (>10 kBq/L), mainly OBT, may be higher than currently assumed.

no privacy, a Xenopus tropicalis mutant, is a model of human Hermansky-Pudlak Syndrome and allows visualization of internal organogenesis during tadpole development.

PubMed

Nakayama, Takuya; Nakajima, Keisuke; Cox, Amanda; Fisher, Marilyn; Howell, Mary; Fish, Margaret B; Yaoita, Yoshio; Grainger, Robert M

2017-06-15

We describe a novel recessive and nonlethal pigmentation mutant in Xenopus tropicalis. The mutant phenotype can be initially observed in tadpoles after stage 39/40, when mutant embryos display markedly reduced pigmentation in the retina and the trunk. By tadpole stage 50 almost all pigmented melanophores have disappeared. Most interestingly, those embryos fail entirely to make pigmented iridophores. The combined reduction/absence of both pigmented iridophores and melanophores renders these embryos virtually transparent, permitting one to easily observe both the developing internal organs and nervous system; accordingly, we named this mutant no privacy (nop). We identified the causative genetic lesion as occurring in the Xenopus homolog of the human Hermansky-Pudlak Syndrome 6 (HPS6) gene, combining several approaches that utilized conventional gene mapping and classical and modern genetic tools available in Xenopus (gynogenesis, BAC transgenesis and TALEN-mediated mutagenesis). The nop allele contains a 10-base deletion that results in truncation of the Hps6 protein. In humans, HPS6 is one of the genes responsible for the congenital disease HPS, pathological symptoms of which include oculocutaneous albinism caused by defects in lysosome-related organelles required for pigment formation. Markers for melanin-producing neural crest cells show that the cells that would give rise to melanocytes are present in nop, though unpigmented. Abnormalities develop at tadpole stages in the pigmented retina when overall pigmentation becomes reduced and large multi-melanosomes are first formed. Ear development is also affected in nop embryos when both zygotic and maternal hsp6 is mutated: otoliths are often reduced or abnormal in morphology, as seen in some mouse HPS mutations, but to our knowledge not described in the BLOC-2 subset of HPS mutations nor described in non-mammalian systems previously. The transparency of the nop line suggests that these animals will aid studies of

The Antidepressant Agomelatine Improves Memory Deterioration and Upregulates CREB and BDNF Gene Expression Levels in Unpredictable Chronic Mild Stress (UCMS)-Exposed Mice

PubMed Central

Gumuslu, Esen; Mutlu, Oguz; Sunnetci, Deniz; Ulak, Guner; Celikyurt, Ipek K.; Cine, Naci; Akar, Furuzan; Savlı, Hakan; Erden, Faruk

2014-01-01

Agomelatine, a novel antidepressant with established clinical efficacy, acts as an agonist of melatonergic MT1 and MT2 receptors and as an antagonist of 5-HT2C receptors. The present study was undertaken to investigate whether chronic treatment with agomelatine would block unpredictable chronic mild stress (UCMS)-induced cognitive deterioration in mice in passive avoidance (PA), modified elevated plus maze (mEPM), novel object recognition (NOR), and Morris water maze (MWM) tests. Moreover, the effects of stress and agomelatine on brain-derived neurotrophic factor (BDNF) and cyclic adenosine monophosphate (cAMP) response element binding protein (CREB) messenger ribonucleic acid (mRNA) levels in the hippocampus was also determined using quantitative real-time polymerase chain reaction (RT-PCR). Male inbred BALB/c mice were treated with agomelatine (10 mg/kg, i.p.), melatonin (10 mg/kg), or vehicle daily for five weeks. The results of this study revealed that UCMS-exposed animals exhibited memory deterioration in the PA, mEPM, NOR, and MWM tests. The chronic administration of melatonin had a positive effect in the PA and +mEPM tests, whereas agomelatine had a partial effect. Both agomelatine and melatonin blocked stress-induced impairment in visual memory in the NOR test and reversed spatial learning and memory impairment in the stressed group in the MWM test. Quantitative RT-PCR revealed that CREB and BDNF gene expression levels were downregulated in UCMS-exposed mice, and these alterations were reversed by chronic agomelatine or melatonin treatment. Thus, agomelatine plays an important role in blocking stress-induced hippocampal memory deterioration and activates molecular mechanisms of memory storage in response to a learning experience. PMID:24634580

Morphology of the caudal spinal cord in Rana (Ranidae) and Xenopus (Pipidae) tadpoles.

PubMed

Nishikawa, K; Wassersug, R

1988-03-08

Using a variety of neuroanatomical and histological techniques, we compare the spinal cord and peripheral nerve distribution in the tails of larvae from Xenopus laevis and three species of Rana. The relatively large, postsacral spinal cord of Xenopus contains abundant motoneurons and their axons. Spinal nerves exit from the spinal cord in a regular array, one nerve per myotome, from the cervical region to near the end of the tail. Somata of motoneurons innervating caudal myotomes are found along the entire length of the tail. In contrast, the caudal cord of Rana is reduced to a filum terminale consisting of little more than an ependymal tube; spinal nerves to all caudal myotomes leave the cord in the sacral region and reach their motor targets via a cauda equina and caudal plexus. Motoneuron cell bodies innervating caudal myotomes are found only in the sacral region. The Rana larval pattern is similar to that of adult frogs and mammals, whereas the Xenopus larval pattern is more like that of salamanders and reptiles. These gross neuroanatomical differences are not due to differences in the size or developmental stage of the tadpoles, but instead are associated with differences in the swimming behavior of the larvae. The presence of motoneurons in the caudal spinal cord of Xenopus may provide local intermyotomal control within the tail; the elongated topography of the cord appears to permit finer, rostral-to-caudal regulation of neuromuscular activity. The Rana spinal cord, on the other hand--with motoneurons clustered anteriorly--may produce concurrent firing of adjacent ipsilateral myotomes, but at the expense of fine intermyotomal regulation. The fact that nerves in the tail of Xenopus enter and exit from the spinal cord locally, as opposed to far anteriorly as in Rana, means that for tadpoles of the same size, reflex arc lengths are many times shorter in Xenopus.

Electrolysed reduced water decreases reactive oxygen species-induced oxidative damage to skeletal muscle and improves performance in broiler chickens exposed to medium-term chronic heat stress.

PubMed

Azad, M A K; Kikusato, M; Zulkifli, I; Toyomizu, M

2013-01-01

1. The present study was designed to achieve a reduction of reactive oxygen species (ROS)-induced oxidative damage to skeletal muscle and to improve the performance of broiler chickens exposed to chronic heat stress. 2. Chickens were given a control diet with normal drinking water, or diets supplemented with cashew nut shell liquid (CNSL) or grape seed extract (GSE), or a control diet with electrolysed reduced water (ERW) for 19 d after hatch. Thereafter, chickens were exposed to a temperature of either 34°C continuously for a period of 5 d, or maintained at 24°C, on the same diets. 3. The control broilers exposed to 34°C showed decreased weight gain and feed consumption and slightly increased ROS production and malondialdehyde (MDA) concentrations in skeletal muscle. The chickens exposed to 34°C and supplemented with ERW showed significantly improved growth performance and lower ROS production and MDA contents in tissues than control broilers exposed to 34°C. Following heat exposure, CNSL chickens performed better with respect to weight gain and feed consumption, but still showed elevated ROS production and skeletal muscle oxidative damage. GSE chickens did not exhibit improved performance or reduced skeletal muscle oxidative damage. 4. In conclusion, this study suggests that ERW could partially inhibit ROS-induced oxidative damage to skeletal muscle and improve growth performance in broiler chickens under medium-term chronic heat treatment.

Mechanical vibrations from tadpoles' flapping tails transform salamander's carnivorous morphology.

PubMed

Michimae, Hirofumi; Nishimura, Kinya; Wakahara, Masami

2005-03-22

Some prey or predator organisms exhibit striking rapid morphological plastic changes with distinct morphology under the condition of predator or prey presence. Remote chemicals propagating from the inducing agents are the prevalent induction cues for most examples of induction of distinct morphs. Sonic and visual cues, as well as chemical cues, are known as triggers for induction of behavioural plasticity. Here we show that hydraulic vibration originating from flapping tails of anuran tadpoles is a key cue in relation to induction of a distinct carnivorous morphology, a broad-headed morph, in larval salamander Hynobius retardatus, which is able to efficiently capture and handle prey. This result was further supported by the fact that simple mechanical vibrations of tail-like vinyl fins were able to induce the morph without any biological cues. Induction of the morph triggered by hydraulic vibration provides a novel concept for understanding the proximate mechanisms of induction of morphological changes.

Where have all the tadpoles gone? Individual genetic tracking of amphibian larvae until adulthood.

PubMed

Ringler, Eva; Mangione, Rosanna; Ringler, Max

2015-07-01

Reliably marking larvae and reidentifying them after metamorphosis is a challenge that has hampered studies on recruitment, dispersal, migration and survivorship of amphibians for a long time, as conventional tags are not reliably retained through metamorphosis. Molecular methods allow unique genetic fingerprints to be established for individuals. Although microsatellite markers have successfully been applied in mark-recapture studies on several animal species, they have never been previously used in amphibians to follow individuals across different life cycle stages. Here, we evaluate microsatellites for genetic across-stages mark-recapture studies in amphibians and test the suitability of available software packages for genotype matching. We sampled tadpoles of the dendrobatid frog Allobates femoralis, which we introduced on a river island in the Nature Reserve 'Les Nouragues' in French Guiana. In two subsequent recapture sessions, we searched for surviving juveniles and adults, respectively. All individuals were genotyped at 14 highly variable microsatellite loci, which yielded unique genetic fingerprints for all individuals. We found large differences in the identification success of the programs tested. The pairwise-relatedness-based approach, conducted with the programs kingroup or ML-Relate, performed best with our data set. Matching ventral patterns of juveniles and adult individuals acted as a control for the reliability of the genetic identification. Our results demonstrate that microsatellite markers are a highly powerful tool for studying amphibian populations on an individual basis. The ability to individually track amphibian tadpoles throughout metamorphosis until adulthood will be of substantial value for future studies on amphibian population ecology and evolution. © 2014 The Authors. Molecular Ecology Resources Published by John Wiley & Sons Ltd.

Three-dimensional reconstruction of the cranial and anterior spinal nerves in early tadpoles of Xenopus laevis (Pipidae, Anura).

PubMed

Naumann, Benjamin; Olsson, Lennart

2018-04-01

Xenopus laevis is one of the most widely used model organism in neurobiology. It is therefore surprising, that no detailed and complete description of the cranial nerves exists for this species. Using classical histological sectioning in combination with fluorescent whole mount antibody staining and micro-computed tomography we prepared a detailed innervation map and a freely-rotatable three-dimensional (3D) model of the cranial nerves and anterior-most spinal nerves of early X. laevis tadpoles. Our results confirm earlier descriptions of the pre-otic cranial nerves and present the first detailed description of the post-otic cranial nerves. Tracing the innervation, we found two previously undescribed head muscles (the processo-articularis and diaphragmatico-branchialis muscles) in X. laevis. Data on the cranial nerve morphology of tadpoles are scarce, and only one other species (Discoglossus pictus) has been described in great detail. A comparison of Xenopus and Discoglossus reveals a relatively conserved pattern of the post-otic and a more variable morphology of the pre-otic cranial nerves. Furthermore, the innervation map and the 3D models presented here can serve as an easily accessible basis to identify alterations of the innervation produced by experimental studies such as genetic gain- and loss of function experiments. © 2017 Wiley Periodicals, Inc.

DNA damage in nasal and brain tissues of canines exposed to air pollutants is associated with evidence of chronic brain inflammation and neurodegeneration.

PubMed

Calderón-Garcidueñas, Lilian; Maronpot, Robert R; Torres-Jardon, Ricardo; Henríquez-Roldán, Carlos; Schoonhoven, Robert; Acuña-Ayala, Hilda; Villarreal-Calderón, Anna; Nakamura, Jun; Fernando, Reshan; Reed, William; Azzarelli, Biagio; Swenberg, James A

2003-01-01

Acute, subchronic, or chronic exposures to particulate matter (PM) and pollutant gases affect people in urban areas and those exposed to fires, disasters, and wars. Respiratory tract inflammation, production of mediators of inflammation capable of reaching the brain, systemic circulation of PM, and disruption of the nasal respiratory and olfactory barriers are likely in these populations. DNA damage is crucial in aging and in age-associated diseases such as Alzheimer's disease. We evaluated apurinic/apyrimidinic (AP) sites in nasal and brain genomic DNA, and explored by immunohistochemistry the expression of nuclear factor NFkappaB p65, inducible nitric oxide synthase (iNOS), cyclo-oxygenase 2 (COX2), metallothionein I and II, apolipoprotein E, amyloid precursor protein (APP), and beta-amyloid(1-42) in healthy dogs naturally exposed to urban pollution in Mexico City. Nickel (Ni) and vanadium (V) were measured by inductively coupled plasma mass spectrometry (ICP-MS). Forty mongrel dogs, ages 7 days-10 years were studied (14 controls from Tlaxcala and 26 exposed to urban pollution in South West Metropolitan Mexico City (SWMMC)). Nasal respiratory and olfactory epithelium were found to be early pollutant targets. Olfactory bulb and hippocampal AP sites were significantly higher in exposed than in control age matched animals. Ni and V were present in a gradient from olfactory mucosa > olfactory bulb > frontal cortex. Exposed dogs had (a) nuclear neuronal NFkappaB p65, (b) endothelial, glial and neuronal iNOS, (c) endothelial and glial COX2, (d) ApoE in neuronal, glial and vascular cells, and (e) APP and beta amyloid(1-42) in neurons, diffuse plaques (the earliest at age 11 months), and in subarachnoid blood vessels. Increased AP sites and the inflammatory and stress protein brain responses were early and significant in dogs exposed to urban pollution. Oil combustion PM-associated metals Ni and V were detected in the brain. There was an acceleration of Alzheimer

Effects of glyphosate and the glyphosate based herbicides Roundup Original(®) and Roundup Transorb(®) on respiratory morphophysiology of bullfrog tadpoles.

PubMed

Rissoli, Rafael Zanelli; Abdalla, Fabio Camargo; Costa, Monica Jones; Rantin, Francisco Tadeu; McKenzie, David John; Kalinin, Ana Lucia

2016-08-01

Glyphosate-based herbicides are widely used in agriculture and are commonly found in water bodies. Roundup Original(®) (RO) contains an isopropylamine glyphosate (GLY) salt containing the surfactant POEA, while Roundup Transorb R(®) (RTR) contains a potassium salt of GLY with unknown surfactants. Both contain different compositions of so-called "inert" ingredients, more toxic than glyphosate. Amphibian tadpoles often experience variations in O2 availability in their aquatic habitats; an ability to tolerate hypoxia can condition their survival and fitness. We evaluated the impacts of sublethal concentrations of GLY (1 mg L(-1)), RO (1 mg L(-1) GLY a.e) and RTR (1 mg L(-1) GLY a.e) on metabolic rate (V·O2 - mLO2 Kg1 h(-1)) of bullfrog tadpoles during normoxia and graded hypoxia, and related this to morphology of their skin, their major site of gas exchange. In control (CT) V·O2 remained unaltered from normoxia until 40 mmHg, indicating a critical O2 tension between 40 and 20 mmHg. GLY significantly reduced V·O2, possibly due to epidermal hypertrophy, which increased O2 diffusion distance to O2 uptake. In contrast, RTR increased V·O2 during hypoxia, indicating an influence of "inert" compounds and surfactants. V·O2 of RO did not differ from CT, suggesting that any increase in V·O2 caused by exposure was antagonized by epidermal hypertrophy. Indeed, all herbicides caused marked alterations in skin morphology, with cell and epithelium wall presenting hyperplasia or hypertrophy and chromatid rupture. In summary, GLY, RO and RTR exert different effects in bullfrog tadpoles, in particular the surfactants and inert compounds appear to influence oxygen uptake. Copyright © 2016 Elsevier Ltd. All rights reserved.

Intra-facility linkage of HIV-positive mothers and HIV-exposed babies into HIV chronic care: rural and urban experience in a resource limited setting.

PubMed

Mugasha, Christine; Kigozi, Joanita; Kiragga, Agnes; Muganzi, Alex; Sewankambo, Nelson; Coutinho, Alex; Nakanjako, Damalie

2014-01-01

Linkage of HIV-infected pregnant women to HIV care remains critical for improvement of maternal and child outcomes through prevention of maternal-to-child transmission of HIV (PMTCT) and subsequent chronic HIV care. This study determined proportions and factors associated with intra-facility linkage to HIV care and Early Infant Diagnosis care (EID) to inform strategic scale up of PMTCT programs. A cross-sectional review of records was done at 2 urban and 3 rural public health care facilities supported by the Infectious Diseases Institute (IDI). HIV-infected pregnant mothers, identified through routine antenatal care (ANC) and HIV-exposed babies were evaluated for enrollment in HIV clinics by 6 weeks post-delivery. Overall, 1,025 HIV-infected pregnant mothers were identified during ANC between January and June, 2012; 267/1,025 (26%) in rural and 743/1,025 (74%) in urban facilities. Of these 375/1,025 (37%) were linked to HIV clinics [67/267(25%) rural and 308/758(41%) urban]. Of 636 HIV-exposed babies, 193 (30%) were linked to EID. Linkage of mother-baby pairs to HIV chronic care and EID was 16% (101/636); 8/179 (4.5%)] in rural and 93/457(20.3%) in urban health facilities. Within rural facilities, ANC registration <28 weeks-of-gestation was associated with mothers' linkage to HIV chronic care [AoR, 2.0 95% CI, 1.1-3.7, p = 0.019] and mothers' multi-parity was associated with baby's linkage to EID; AoR 4.4 (1.3-15.1), p = 0.023. Stigma, long distance to health facilities and vertical PMTCT services affected linkage in rural facilities, while peer mothers, infant feeding services, long patient queues and limited privacy hindered linkage to HIV care in urban settings. Post-natal linkage of HIV-infected mothers to chronic HIV care and HIV-exposed babies to EID programs was low. Barriers to linkage to HIV care vary in urban and rural settings. We recommend targeted interventions to rapidly improve linkage to antiretroviral therapy for elimination of MTCT.

Chronic Obstructive Pulmonary Disease Mortality in Diesel-Exposed Railroad Workers

PubMed Central

Hart, Jaime E.; Laden, Francine; Schenker, Marc B.; Garshick, Eric

2006-01-01

Diesel exhaust is a mixture of combustion gases and ultrafine particles coated with organic compounds. There is concern whether exposure can result in or worsen obstructive airway diseases, but there is only limited information to assess this risk. U.S. railroad workers have been exposed to diesel exhaust since diesel locomotives were introduced after World War II, and by 1959, 95% of the locomotives were diesel. We conducted a case–control study of railroad worker deaths between 1981 and 1982 using U.S. Railroad Retirement Board job records and next-of-kin smoking, residential, and vitamin use histories. There were 536 cases with chronic obstructive pulmonary disease (COPD) and 1,525 controls with causes of death not related to diesel exhaust or fine particle exposure. After adjustment for age, race, smoking, U.S. Census region of death, vitamin use, and total years off work, engineers and conductors with diesel-exhaust exposure from operating trains had an increased risk of COPD mortality. The odds of COPD mortality increased with years of work in these jobs, and those who had worked ≥ 16 years as an engineer or conductor after 1959 had an odds ratio of 1.61 (95% confidence interval, 1.12–2.30). These results suggest that diesel-exhaust exposure contributed to COPD mortality in these workers. Further study is needed to assess whether this risk is observed after exposure to exhaust from later-generation diesel engines with modern emission controls. PMID:16835052

The complete mitogenome of the Australian tadpole shrimp Triops australiensis (Spencer & Hall, 1895) (Crustacea: Branchiopoda: Notostraca).

PubMed

Gan, Han Ming; Tan, Mun Hua; Lee, Yin Peng; Austin, Christopher M

2016-05-01

The mitochondrial genome sequence of the Australian tadpole shrimp, Triops australiensis is presented (GenBank Accession Number: NC_024439) and compared with other Triops species. Triops australiensis has a mitochondrial genome of 15,125 base pairs consisting of 13 protein-coding genes, 2 ribosomal subunit genes, 22 transfer RNAs, and a non-coding AT-rich region. The T. australiensis mitogenome is composed of 36.4% A, 16.1% C, 12.3% G and 35.1% T. The mitogenome gene order conforms to the primitive arrangement for Branchiopod crustaceans, which is also conserved within the Pancrustacean.

Attenuation of the cortisol response to stress in female rainbow trout chronically exposed to dietary selenomethionine.

PubMed

Wiseman, Steve; Thomas, Jith K; McPhee, Landon; Hursky, Olesya; Raine, Jason C; Pietrock, Michael; Giesy, John P; Hecker, Markus; Janz, David M

2011-10-01

Selenomethionine (Se-Met) is the major dietary form of selenium (Se). While Se is a required nutrient, it can also influence the physiological stress response because it stimulates greater concentrations of cortisol in blood plasma of exposed fish. However, little is known about the effects of exposure to Se on the ability to cope with a secondary stressor. In the current study, female rainbow trout were exposed to an environmentally relevant dietary concentration (8.47 mg Se/kg dry mass (dm)) of Se-Met for 126 d, after which time fish were subjected to a 3-min handling stressor and sampled at 2h and 24h post-stressor exposure. Concentrations of cortisol, cortisone, glucose, and lactate in blood plasma and concentrations of glycogen and triglycerides in liver and muscle were determined. Abundances of transcripts of proteins involved in corticosteroidogenesis were determined using quantitative RT-PCR. Concentrations of cortisol were significantly greater in blood plasma of trout exposed to Se-Met, relative to control trout sampled prior to the handling stressor. A typical response of cortisol to the handling stressor was observed in the control trout. However, trout exposed to Se-Met were unable to mount a cortisol response to the handling stressor. Concentrations of cortisone, the inactive metabolite of cortisol, were significantly greater following the handling stressor in trout exposed to Se-Met. In trout exposed to Se-Met, transcript abundance of melanocortin 2 receptor (mc2r) and peripheral benzodiazepine receptor (pbr) were greater, which is consistent with the conclusion that synthesis of cortisol was greater. However, abundances of transcripts of cytochrome P450 side-chain cleavage (p450scc) and cytochrome P450 11B1 (cyp11b1) were not significantly different between controls and Se-Met exposed trout. Exposure to Se-Met affected accumulation and tissue partitioning of glycogen and triglycerides in liver and muscle as concentrations of these energy reserves

The experiences and needs of individuals with disabilities exposed to chronic political violence.

PubMed

Shpigelman, Carmit-Noa; Gelkopf, Marc

2017-01-01

Purpose The main objective of this study was to understand, describe and map the experiences, challenges and needs of individuals with lifelong disabilities, who have been exposed to chronic politically violent events (terror, war or continuous missile attacks) in Israel. Method The study was conducted within the qualitative-constructivist paradigm. Three focus groups consisting of 18 individuals with lifelong disabilities were conducted; each focus group included a specific disability type (physical, visual and hearing impairment). Results The participants reported encountering environmental barriers, such as inaccessibly of the physical environment and information as well as dependency on others. These barriers limited the participants' functioning during emergency period and thus increased their level of distress. The participants also emphasized their physical, social and psychological needs. Conclusions The needs of individuals with disabilities in emergency situations can be met if they have a safe place to stay in, are with someone else, and plan every daily action in advance. It is also imperative to provide accessible services and information. Furthermore, it is recommended to develop training sessions for individuals with disabilities and for service providers regarding how to locate, communicate with and assist individuals with disabilities during security threat situations. Implications for Rehabilitation Successful coping of individuals with lifelong disabilities with chronic politically violent events depends on personal and organizational accommodations. Besides an accessible physical environment, the information provided should be available and accessible through mass media and assistive technologies. A comprehensive emergency service for various disabilities is needed. Service providers should be trained on how to locate, communicate with, and assist individuals with disabilities during security threat situations.

Effectiveness evaluation of glyphosate oxidation employing the H(2)O(2)/UVC process: toxicity assays with Vibrio fischeri and Rhinella arenarum tadpoles.

PubMed

Junges, Celina M; Vidal, Eduardo E; Attademo, Andrés M; Mariani, Melisa L; Cardell, Leandro; Negro, Antonio C; Cassano, Alberto; Peltzer, Paola M; Lajmanovich, Rafael C; Zalazar, Cristina S

2013-01-01

The H(2)O(2)/UVC process was applied to the photodegradation of a commercial formulation of glyphosate in water. Two organisms (Vibrio fischeri bacteria and Rhinella arenarum tadpoles) were used to investigate the toxicity of glyphosate in samples M(1,) M(2), and M(3) following different photodegradation reaction times (120, 240 and 360 min, respectively) that had differing amounts of residual H(2)O(2). Subsamples of M(1), M(2), and M(3) were then used to create samples M(1,E), M(2,E) and M(3,E) in which the H(2)O(2) had been removed. Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities were measured in tadpoles to determine possible sub-lethal effects. In V. fischeri, M(1,E), which was collected early in the photodegradation process, caused 52% inhibition, while M(3,E), which was collected at the end of the photodegradation process, caused only 17% inhibition. Survival of tadpoles was 100% in samples M(2), M(3), and in M(1,E), M(2,E) and M(3,E). The lowest percentages of enzymatic inhibition were observed in samples without removal of H(2)O(2): 13.96% (AChE) and 16% (BChE) for M(2), and 24.12% (AChE) and 13.83% (BChE) for M(3). These results show the efficiency of the H(2)O(2)/UVC process in reducing the toxicity of water or wastewater polluted by commercial formulations of glyphosate. According to the ecotoxicity assays, the conditions corresponding to M(2) (11 ± 1 mg a.e. L(-1) glyphosate and 11 ± 1 mg L(-1) H(2)O(2)) could be used as a final point for glyphosate treatment with the H(2)O(2)/UV process.

Single olfactory organ associated with prosencephalic malformation and cyclopia in a Xenopus laevis tadpole.

PubMed

Magrassi, L; Graziadei, P P

1987-06-02

A cyclops Xenopus laevis tadpole with a single olfactory organ is described. At a stage comparable to 48, the telencephalon was severely atrophic and only the region where the olfactory fibres terminated appeared to have the cytoarchitecture of the olfactory bulb. In this animal the central nervous system (CNS) appeared normally developed only posterior to the preoptic area. The hypothesis of a diencephalic origin of the region where the olfactory fibres terminated is discussed in the light of our previous results of olfactory placode transplantation. By analogy between this case and other malformations (cyclopia, holoprosencephaly) in higher vertebrates and humans, the need is emphasized for a more precise anatomical description of the olfactory input in related malformations.

Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on development of anuran amphibians

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jung, R.E.; Walker, M.K.

1997-02-01

The authors exposed anuran eggs and tadpoles to vehicle control (0.7% acetone) or waterborne [{sup 3}H]2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) for 24 h and subsequently raised them in clean water. Neither American toads nor green frogs exhibited TCDD-related mortality, but leopard frogs showed significantly increased mortality over controls. Eggs and tadpoles eliminated TCDD relatively quickly compared with published data for other vertebrates, with t{sub {1/2}} of 1 to 5 d (American toad), 2 to 7 d (leopard frog), and 4 to 6 d (green frog). Elimination rates were slowest for tadpoles fed nothing, fastest for those fed a low-fat diet, and intermediate formore » those fed a high-fat diet. Although not significant, American toads exposed to {ge}0.03 {micro}g TCDD/L appeared to metamorphose earlier, and those exposed to higher TCDD treatments appeared to metamorphose at a larger body mass than controls. Comparisons of these results with studies of fish early life stages suggest that anuran eggs and tadpoles eliminate TCDD more rapidly and are 100- to 1,000-fold less sensitive to its deleterious effects during development. These differences may be related to differences in metabolic rate, patterns of lipid storage and utilization, and aryl hydrocarbon receptor binding and signal transduction.« less

Alterations of Hair and Nail Content of Selected Trace Elements in Nonoccupationally Exposed Patients with Chronic Depression from Different Geographical Regions

PubMed Central

Liao, Kuan-Yung; Liao, Heng-Hsin; Niziński, Przemysław; Momčilović, Berislav; Jabłońska-Czapla, Magdalena; Prystupa, Andrzej; Sak, Jarosław J.; Kocjan, Ryszard

2017-01-01

The aim of this study was to determine if altered levels of selected trace elements manifest themselves during chronic depression. To identify elements strongly associated with chronic depression, relationships between the elemental contents of hair and nails and the interelement correlations were checked. Inductively coupled plasma mass spectrometry and ion chromatography were used to evaluate the contents of Zn, Cu, Co, Pb, Mn, and Fe in hair and nail samples from a total of 415 subjects (295 patients and 120 healthy volunteers). The study included logistic regression models to predict the probability of chronic depression. To investigate possible intercorrelations among the studied elements, the scaled principal component analysis was used. The research has revealed differences in TE levels in the group of depressed men and women in comparison to the healthy subjects. Statistically significant differences in both hair and nails contents of several elements were observed. Our study also provides strong evidence that the intermediary metabolism of certain elements is age- and gender-dependent. Zn, Mn, Pb, and Fe contents in hair/nails seem to be strongly associated with chronic depression. We found no statistically significant residence-related differences in the contents of studied elements in nonoccupationally exposed patients and healthy subjects. PMID:28386550

Alterations of Hair and Nail Content of Selected Trace Elements in Nonoccupationally Exposed Patients with Chronic Depression from Different Geographical Regions.

PubMed

Błażewicz, Anna; Liao, Kuan-Yung; Liao, Heng-Hsin; Niziński, Przemysław; Komsta, Łukasz; Momčilović, Berislav; Jabłońska-Czapla, Magdalena; Michalski, Rajmund; Prystupa, Andrzej; Sak, Jarosław J; Kocjan, Ryszard

2017-01-01

The aim of this study was to determine if altered levels of selected trace elements manifest themselves during chronic depression. To identify elements strongly associated with chronic depression, relationships between the elemental contents of hair and nails and the interelement correlations were checked. Inductively coupled plasma mass spectrometry and ion chromatography were used to evaluate the contents of Zn, Cu, Co, Pb, Mn, and Fe in hair and nail samples from a total of 415 subjects (295 patients and 120 healthy volunteers). The study included logistic regression models to predict the probability of chronic depression. To investigate possible intercorrelations among the studied elements, the scaled principal component analysis was used. The research has revealed differences in TE levels in the group of depressed men and women in comparison to the healthy subjects. Statistically significant differences in both hair and nails contents of several elements were observed. Our study also provides strong evidence that the intermediary metabolism of certain elements is age- and gender-dependent. Zn, Mn, Pb, and Fe contents in hair/nails seem to be strongly associated with chronic depression. We found no statistically significant residence-related differences in the contents of studied elements in nonoccupationally exposed patients and healthy subjects.

RESISTANCE TO X-IRRADIATION BY EMBRYONIC CELLS OF THE LIMB-BUDS OF TADPOLES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allen, B.M.; Ewell, L.M.

1959-01-01

Both total-body irradiation and shielding of the trunk were used to study the effects of x irradiation from 1000 to 30000 r upon the limb-buds of Bufo boreas and Hyla regilla tadpoles. The object was to test the view that the younger the cells the more sensitive they are to irradiation. The answer is negative. If there is any special susceptibility of these undifferentiated cells it should appear at levels far below the 30000 r maximum employed. A sharp distinction is made between the very susceptible mitotic cells and the resistant non-dividing embryonic cells that have been accumulated in suchmore » numbers that they may rapidly differentiate into the characteristic limb tissues under the stimulus of the thyroid hormone. Many irradiated ectoderm cells were changed to form bizarre excrescences but were not destroyed. Unicellular cuthneous gland cells continued to arise even after the heaviest irradiation. Irradiated tadpoles with hind limb-buds from 0.6 mm down to 0.2 mm length were unable to develop normal limbs. This capacity was propontional to the number of non-dividing embryonic cells stored at the time of irradiation. Irradiation of 5000, equal degree but the rapidity was greatest in the cases of higher dosage. Not only did these levels of irradiation fail to destroy the non-dividing embryonic cells but they did not effect their pre-deterrmined specificity nor modify their capacity for subsequent differentiation and growth. Exposure to a thyroxin solution caused the hind limb-buds without visible differentiation of cells to grow from a length of 0.8 or 0.9 mm or 1.0 mm at the time of irradiation to a length of as much as 5.0 mm in the course of 7 days. Development of thigh, shank, ankle, and toes was complete. Microscopic studies showed characteristic tissues such as cartilage, connective tissue, and muscle, developed to a comparable degree in control and irradiated specimens. (auth)« less

Intra-Facility Linkage of HIV-Positive Mothers and HIV-Exposed Babies into HIV Chronic Care: Rural and Urban Experience in a Resource Limited Setting

PubMed Central

Mugasha, Christine; Kigozi, Joanita; Kiragga, Agnes; Muganzi, Alex; Sewankambo, Nelson; Coutinho, Alex; Nakanjako, Damalie

2014-01-01

Introduction Linkage of HIV-infected pregnant women to HIV care remains critical for improvement of maternal and child outcomes through prevention of maternal-to-child transmission of HIV (PMTCT) and subsequent chronic HIV care. This study determined proportions and factors associated with intra-facility linkage to HIV care and Early Infant Diagnosis care (EID) to inform strategic scale up of PMTCT programs. Methods A cross-sectional review of records was done at 2 urban and 3 rural public health care facilities supported by the Infectious Diseases Institute (IDI). HIV-infected pregnant mothers, identified through routine antenatal care (ANC) and HIV-exposed babies were evaluated for enrollment in HIV clinics by 6 weeks post-delivery. Results Overall, 1,025 HIV-infected pregnant mothers were identified during ANC between January and June, 2012; 267/1,025 (26%) in rural and 743/1,025 (74%) in urban facilities. Of these 375/1,025 (37%) were linked to HIV clinics [67/267(25%) rural and 308/758(41%) urban]. Of 636 HIV-exposed babies, 193 (30%) were linked to EID. Linkage of mother-baby pairs to HIV chronic care and EID was 16% (101/636); 8/179 (4.5%)] in rural and 93/457(20.3%) in urban health facilities. Within rural facilities, ANC registration <28 weeks-of-gestation was associated with mothers' linkage to HIV chronic care [AoR, 2.0 95% CI, 1.1–3.7, p = 0.019] and mothers' multi-parity was associated with baby's linkage to EID; AoR 4.4 (1.3–15.1), p = 0.023. Stigma, long distance to health facilities and vertical PMTCT services affected linkage in rural facilities, while peer mothers, infant feeding services, long patient queues and limited privacy hindered linkage to HIV care in urban settings. Conclusion Post-natal linkage of HIV-infected mothers to chronic HIV care and HIV-exposed babies to EID programs was low. Barriers to linkage to HIV care vary in urban and rural settings. We recommend targeted interventions to rapidly improve linkage to

Effects of maturation and acidosis on the chaos-like complexity of the neural respiratory output in the isolated brainstem of the tadpole, Rana esculenta.

PubMed

Straus, Christian; Samara, Ziyad; Fiamma, Marie-Noëlle; Bautin, Nathalie; Ranohavimparany, Anja; Le Coz, Patrick; Golmard, Jean-Louis; Darré, Pierre; Zelter, Marc; Poon, Chi-Sang; Similowski, Thomas

2011-05-01

Human ventilation at rest exhibits mathematical chaos-like complexity that can be described as long-term unpredictability mediated (in whole or in part) by some low-dimensional nonlinear deterministic process. Although various physiological and pathological situations can affect respiratory complexity, the underlying mechanisms remain incompletely elucidated. If such chaos-like complexity is an intrinsic property of central respiratory generators, it should appear or increase when these structures mature or are stimulated. To test this hypothesis, we employed the isolated tadpole brainstem model [Rana (Pelophylax) esculenta] and recorded the neural respiratory output (buccal and lung rhythms) of pre- (n = 8) and postmetamorphic tadpoles (n = 8), at physiologic (7.8) and acidic pH (7.4). We analyzed the root mean square of the cranial nerve V or VII neurograms. Development and acidosis had no effect on buccal period. Lung frequency increased with development (P < 0.0001). It also increased with acidosis, but in postmetamorphic tadpoles only (P < 0.05). The noise-titration technique evidenced low-dimensional nonlinearities in all the postmetamorphic brainstems, at both pH. Chaos-like complexity, assessed through the noise limit, increased from pH 7.8 to pH 7.4 (P < 0.01). In contrast, linear models best fitted the ventilatory rhythm in all but one of the premetamorphic preparations at pH 7.8 (P < 0.005 vs. postmetamorphic) and in four at pH 7.4 (not significant vs. postmetamorphic). Therefore, in a lower vertebrate model, the brainstem respiratory central rhythm generator accounts for ventilatory chaos-like complexity, especially in the postmetamorphic stage and at low pH. According to the ventilatory generators homology theory, this may also be the case in mammals.

Are radiosensitivity data derived from natural field conditions consistent with data from controlled exposures? A case study of Chernobyl wildlife chronically exposed to low dose rates.

PubMed

Garnier-Laplace, J; Geras'kin, S; Della-Vedova, C; Beaugelin-Seiller, K; Hinton, T G; Real, A; Oudalova, A

2013-07-01

The discrepancy between laboratory or controlled conditions ecotoxicity tests and field data on wildlife chronically exposed to ionising radiation is presented for the first time. We reviewed the available chronic radiotoxicity data acquired in contaminated fields and used a statistical methodology to support the comparison with knowledge on inter-species variation of sensitivity to controlled external γ irradiation. We focus on the Chernobyl Exclusion Zone and effects data on terrestrial wildlife reported in the literature corresponding to chronic dose rate exposure situations (from background ~100 nGy/h up to ~10 mGy/h). When needed, we reconstructed the dose rate to organisms and obtained consistent unbiased data sets necessary to establish the dose rate-effect relationship for a number of different species and endpoints. Then, we compared the range of variation of radiosensitivity of species from the Chernobyl-Exclusion Zone with the statistical distribution established for terrestrial species chronically exposed to purely gamma external irradiation (or chronic Species radioSensitivity Distribution - SSD). We found that the best estimate of the median value (HDR50) of the distribution established for field conditions at Chernobyl (about 100 μGy/h) was eight times lower than the one from controlled experiments (about 850 μGy/h), suggesting that organisms in their natural environmental were more sensitive to radiation. This first comparison highlights the lack of mechanistic understanding and the potential confusion coming from sampling strategies in the field. To confirm the apparent higher sensitive of wildlife in the Chernobyl Exclusion Zone, we call for more a robust strategy in field, with adequate design to deal with confounding factors. Copyright © 2012 Elsevier Ltd. All rights reserved.

Intersex Occurrence in Rainbow Trout (Oncorhynchus mykiss) Male Fry Chronically Exposed to Ethynylestradiol

PubMed Central

Depiereux, Sophie; Liagre, Mélanie; Danis, Lorraine; De Meulder, Bertrand; Depiereux, Eric; Segner, Helmut; Kestemont, Patrick

2014-01-01

This study aimed to investigate the male-to-female morphological and physiological transdifferentiation process in rainbow trout (Oncorhynchus mykiss) exposed to exogenous estrogens. The first objective was to elucidate whether trout develop intersex gonads under exposure to low levels of estrogen. To this end, the gonads of an all-male population of fry exposed chronically (from 60 to 136 days post fertilization – dpf) to several doses (from environmentally relevant 0.01 µg/L to supra-environmental levels: 0.1, 1 and 10 µg/L) of the potent synthetic estrogen ethynylestradiol (EE2) were examined histologically. The morphological evaluations were underpinned by the analysis of gonad steroid (testosterone, estradiol and 11-ketotestosterone) levels and of brain and gonad gene expression, including estrogen-responsive genes and genes involved in sex differentiation in (gonads: cyp19a1a, ER isoforms, vtg, dmrt1, sox9a2; sdY; cyp11b; brain: cyp19a1b, ER isoforms). Intersex gonads were observed from the first concentration used (0.01 µg EE2/L) and sexual inversion could be detected from 0.1 µg EE2/L. This was accompanied by a linear decrease in 11-KT levels, whereas no effect on E2 and T levels was observed. Q-PCR results from the gonads showed downregulation of testicular markers (dmrt1, sox9a2; sdY; cyp11b) with increasing EE2 exposure concentrations, and upregulation of the female vtg gene. No evidence was found for a direct involvement of aromatase in the sex conversion process. The results from this study provide evidence that gonads of male trout respond to estrogen exposure by intersex formation and, with increasing concentration, by morphological and physiological conversion to phenotypic ovaries. However, supra-environmental estrogen concentrations are needed to induce these changes. PMID:25033040

Variation in salinity tolerance among larval anurans: implications for community composition and the spread of an invasive, non-native species

USGS Publications Warehouse

Brown, Mary E.; Walls, Susan C.

2013-01-01

Amphibians in freshwater coastal wetlands periodically experience acute exposure to salinity from hurricane-related overwash events, as well as chronic exposure associated with rising sea levels. In a comparative experimental approach, we examined whether seven species of anuran amphibians vary in their tolerance to changes in salinity. In a laboratory study, we exposed larval Hyla cinerea (Green Treefrog), H. squirella (Squirrel Treefrog), Lithobates catesbeianus (American Bullfrog), L. sphenocephalus (Southern Leopard Frog), Anaxyrus terrestris (Southern Toad), and Gastrophryne carolinensis (Eastern Narrow-mouthed Toad) from an inland population in north central Florida, USA, and Osteopilus septentrionalis (Cuban Treefrog) tadpoles from an inland population in southwest Florida, to acute salinity for 72 h. For each species, we replicated trials in which tadpoles were exposed to salinities of 0.2 (control), 5, 10, 12, 14, and 16 ppt. For all species, tadpoles reared in the control and 5 ppt treatments had 96.7–100% survival. No individuals of G. carolinensis survived at salinities exceeding 5 ppt and no individuals of any species survived in the 14 or 16 ppt treatments. For all other native species, survival at 10 ppt ranged from 46.7 to 80%, but declined to 0% at 12 ppt (except for H. cinerea, of which only 3.3% survived at 12 ppt). In contrast, all individuals of the invasive, non-native O. septentrionalis survived exposure to a salinity of 10 ppt, and survival in this species remained relatively high at 12 ppt. Our results illustrate that the non-native O. septentrionalis has a higher salinity tolerance than the native species tested, which may contribute to its invasion potential. Moreover, species commonly associated with coastal freshwater wetlands differ in their salinity tolerances, suggesting that salt water intrusion due to storm surges and sea level rise may affect the species composition of these ecosystems.

Effects of Environmental Contamination and Acute Toxicity of N-Nitrate on Early Life Stages of Endemic Arboreal Frog, Polypedates cruciger (Blyth, 1852).

PubMed

Balangoda, Anusha; Deepananda, K H M Ashoka; Wegiriya, H C E

2018-02-01

This study investigated the potential toxic effects of environmentally relevant nitrate concentrations on development, growth, and mortality of early life stages of common hour-glass tree frog, Polypedates cruciger. Tadpoles from hatchlings through pre-adult were exposed to environmentally relevant nitrate concentrations detected in Mirissa, Sri Lanka. Newly hatched, external gill stage, and internal gill stage tadpoles were exposed to potassium nitrate for bioassay tests. No behavioral changes or abnormalities were observed in control and nitrate-induced group. However, detected environmental nitrate concentration significantly increased (p < 0.05) the growth of the tadpoles up to 25 days old. Results revealed that newly hatched and external gill stage was more susceptible to the nitrate pollution than internal gill stage. The results suggest that environmentally relevant nitrate can cause mortality on the amphibian population in ecosystems associated with agro-pastoral activities through altering the growth and direct toxicological effects on the survivorship.

Normalized Shape and Location of Perturbed Craniofacial Structures in the Xenopus Tadpole Reveal an Innate Ability to Achieve Correct Morphology

PubMed Central

Vandenberg, Laura N.; Adams, Dany S.; Levin, Michael

2012-01-01

Background Embryonic development can often adjust its morphogenetic processes to counteract external perturbation. The existence of self-monitoring responses during pattern formation is of considerable importance to the biomedicine of birth defects, but has not been quantitatively addressed. To understand the computational capabilities of biological tissues in a molecularly-tractable model system, we induced craniofacial defects in Xenopus embryos, then tracked tadpoles with craniofacial deformities and used geometric morphometric techniques to characterize changes in the shape and position of the craniofacial structures. Results Canonical variate analysis revealed that the shapes and relative positions of perturbed jaws and branchial arches were corrected during the first few months of tadpole development. Analysis of the relative movements of the anterior-most structures indicates that misplaced structures move along the anterior-posterior and left-right axes in ways that are significantly different from their normal movements. Conclusions Our data suggest a model in which craniofacial structures utilize a measuring mechanism to assess and adjust their location relative to other local organs. Understanding the correction mechanisms at work in this system could lead to the better understanding of the adaptive decision-making capabilities of living tissues and suggest new approaches to correct birth defects in humans. PMID:22411736

Variability of Rheotaxis Behaviors in Larval Bullfrogs Highlights Species Diversity in Lateral Line Function

PubMed Central

Brown, Erika E. A.

2016-01-01

The morphology and distribution of lateral line neuromasts vary between ecomorphological types of anuran tadpoles, but little is known about how this structural variability contributes to differences in lateral-line mediated behaviors. Previous research identified distinct differences in one such behavior, positive rheotaxis towards the source of a flow, in two tadpole species, the African clawed frog (Xenopus laevis; type 1) and the American bullfrog (Rana catesbeiana; type 4). Because these two species had been tested under different flow conditions, we re-evaluated these findings by quantifying flow-sensing behaviors of bullfrog tadpoles in the same flow field in which X. laevis tadpoles had been tested previously. Early larval bullfrog tadpoles were exposed to flow in the dark, in the presence of a discrete light cue, and after treatment with the ototoxin gentamicin. In response to flow, tadpoles moved downstream, closer to a side wall, and higher in the water column, but they did not station-hold. Tadpoles exhibited positive rheotaxis, but with long latencies, low to moderate accuracy, and considerable individual variability. This is in contrast to the robust, stereotyped station-holding and accurate rheotaxis of X. laevis tadpoles. The presence of a discrete visual cue and gentamicin treatment altered spatial positioning and disrupted rheotaxis in both tadpole species. Species differences in lateral-line mediated behaviors may reflect differences in neuromast number and distribution, life history, or perceptual salience of other environmental cues. PMID:27870909

Octylphenol and UV-B radiation alter larval development and hypothalamic gene expression in the leopard frog (Rana pipiens).

PubMed

Crump, Douglas; Lean, David; Trudeau, Vance L

2002-03-01

We assessed octylphenol (OP), an estrogenic endocrine-disrupting chemical, and UV-B radiation, a known stressor in amphibian development, for their effects on hypothalamic gene expression and premetamorphic development in the leopard frog Rana pipiens. Newly hatched tadpoles were exposed for 10 days to OP alone at two different dose levels; to subambient UV-B radiation alone; and to two combinations of OP and UV-B. Control animals were exposed to ethanol vehicle (0.01%) exposure, a subset of tadpoles from each treatment group was raised to metamorphosis to assess differences in body weight and time required for hindlimb emergence. Tadpoles from one of the OP/UV-B combination groups had greater body weight and earlier hindlimb emergence (p < 0.05), but neither OP nor UV-B alone produced significant changes in body weight or hindlimb emergence, indicating a potential mechanism of interaction between OP and UV-B. We hypothesized that the developing hypothalamus might be a potential environmental sensor for neurotoxicologic studies because of its role in the endocrine control of metamorphosis. We used a differential display strategy to identify candidate genes differentially expressed in the hypothalamic region of the exposed tadpoles. Homology cloning was performed to obtain R. pipiens glutamate decarboxylases--GAD65 and GAD67, enzymes involved in the synthesis of the neurotransmitter gamma-aminobutyric acid (GABA). cDNA expression profiles revealed that OP and UV-B affected the levels of several candidate transcripts in tadpole (i.e., Nck, Ash, and phospholipase C gamma-binding protein 4 and brain angiogenesis inhibitor-3) and metamorph (i.e., GAD67, cytochrome C oxidase, and brain angiogenesis inhibitor-2 and -3) brains. This study represents a novel approach in toxicology that combines physiologic and molecular end points and indicates that levels of OP commonly found in the environment and subambient levels of UV-B alter the expression of important hypothalamic

Octylphenol and UV-B radiation alter larval development and hypothalamic gene expression in the leopard frog (Rana pipiens).

PubMed Central

Crump, Douglas; Lean, David; Trudeau, Vance L

2002-01-01

We assessed octylphenol (OP), an estrogenic endocrine-disrupting chemical, and UV-B radiation, a known stressor in amphibian development, for their effects on hypothalamic gene expression and premetamorphic development in the leopard frog Rana pipiens. Newly hatched tadpoles were exposed for 10 days to OP alone at two different dose levels; to subambient UV-B radiation alone; and to two combinations of OP and UV-B. Control animals were exposed to ethanol vehicle (0.01%) exposure, a subset of tadpoles from each treatment group was raised to metamorphosis to assess differences in body weight and time required for hindlimb emergence. Tadpoles from one of the OP/UV-B combination groups had greater body weight and earlier hindlimb emergence (p < 0.05), but neither OP nor UV-B alone produced significant changes in body weight or hindlimb emergence, indicating a potential mechanism of interaction between OP and UV-B. We hypothesized that the developing hypothalamus might be a potential environmental sensor for neurotoxicologic studies because of its role in the endocrine control of metamorphosis. We used a differential display strategy to identify candidate genes differentially expressed in the hypothalamic region of the exposed tadpoles. Homology cloning was performed to obtain R. pipiens glutamate decarboxylases--GAD65 and GAD67, enzymes involved in the synthesis of the neurotransmitter gamma-aminobutyric acid (GABA). cDNA expression profiles revealed that OP and UV-B affected the levels of several candidate transcripts in tadpole (i.e., Nck, Ash, and phospholipase C gamma-binding protein 4 and brain angiogenesis inhibitor-3) and metamorph (i.e., GAD67, cytochrome C oxidase, and brain angiogenesis inhibitor-2 and -3) brains. This study represents a novel approach in toxicology that combines physiologic and molecular end points and indicates that levels of OP commonly found in the environment and subambient levels of UV-B alter the expression of important hypothalamic

Reproductive Alterations in Chronically Exposed Female Mice to Environmentally Relevant Doses of a Mixture of Phthalates and Alkylphenols.

PubMed

Patiño-García, Daniel; Cruz-Fernandes, Leonor; Buñay, Julio; Palomino, Jaime; Moreno, Ricardo D

2018-02-01

Endocrine-disrupting chemicals (EDCs) are exogenous compounds that modify hormone biosynthesis, causing adverse effects to human health. Among them, phthalates and alkylphenols are important due to their wide use in plastics, detergents, personal care products, cosmetics, and food packaging. However, their conjoint effects over reproductive female health have not been addressed. The aim of this work was to test the effect of chronically exposed female mice to a mixture of three phthalates [bis (2-ethylhexyl), dibutyl, and benzyl butyl] and two alkylphenols (4-nonylphenol and 4-tert-octylphenol) from conception to adulthood at environmentally relevant doses. These EDCs were administered in two doses: one below the minimal risk dose to cause adverse effects on human development and reproduction [1 mg/kg body weight (BW)/d of the total mixture] and the other one based on the reference value close to occupational exposure in humans (10 mg/kg BW/d of the total mixture). Our results show that both doses had similar effects regarding the uterus and ovary relative weight, estrous cyclicity, serum levels of progesterone and 17β-estradiol, and expression of key elements in the steroidogenesis pathway (acute steroidogenic regulatory protein and CYP19A1). However, only the 1-mg/kg BW/d dose delayed the onset of puberty and the transition from preantral to antral follicles, whereas the 10-mg/kg BW/d dose decreased the number of antral follicles and gonadotropin receptor expression. In addition, we observed changes in several fertility parameters in exposed females and in their progeny (F2 generation). In conclusion, our results indicate that chronic exposure to a complex EDC mixture, at environmentally relevant doses, modifies reproductive parameters in female mice. Copyright © 2018 Endocrine Society.

Thyroid Hormone Acts Locally to Increase Neurogenesis, Neuronal Differentiation, and Dendritic Arbor Elaboration in the Tadpole Visual System

PubMed Central

Thompson, Christopher K.

2016-01-01

Thyroid hormone (TH) regulates many cellular events underlying perinatal brain development in vertebrates. Whether and how TH regulates brain development when neural circuits are first forming is less clear. Furthermore, although the molecular mechanisms that impose spatiotemporal constraints on TH action in the brain have been described, the effects of local TH signaling are poorly understood. We determined the effects of manipulating TH signaling on development of the optic tectum in stage 46–49 Xenopus laevis tadpoles. Global TH treatment caused large-scale morphological effects in tadpoles, including changes in brain morphology and increased tectal cell proliferation. Either increasing or decreasing endogenous TH signaling in tectum, by combining targeted DIO3 knockdown and methimazole, led to corresponding changes in tectal cell proliferation. Local increases in TH, accomplished by injecting suspensions of tri-iodothyronine (T3) in coconut oil into the midbrain ventricle or into the eye, selectively increased tectal or retinal cell proliferation, respectively. In vivo time-lapse imaging demonstrated that local TH first increased tectal progenitor cell proliferation, expanding the progenitor pool, and subsequently increased neuronal differentiation. Local T3 also dramatically increased dendritic arbor growth in neurons that had already reached a growth plateau. The time-lapse data indicate that the same cells are differentially sensitive to T3 at different time points. Finally, TH increased expression of genes pertaining to proliferation and neuronal differentiation. These experiments indicate that endogenous TH locally regulates neurogenesis at developmental stages relevant to circuit assembly by affecting cell proliferation and differentiation and by acting on neurons to increase dendritic arbor elaboration. SIGNIFICANCE STATEMENT Thyroid hormone (TH) is a critical regulator of perinatal brain development in vertebrates. Abnormal TH signaling in early

Effects of acamprosate on attentional set-shifting and cellular function in the prefrontal cortex of chronic alcohol-exposed mice

NASA Astrophysics Data System (ADS)

Hu, Wei

Background: The medial prefrontal cortex (mPFC) inhibits impulsive and compulsive behaviors that characterize drug abuse and dependence. Acamprosate is the leading medication approved for the maintenance of abstinence, shown to reduce craving and relapse in animal models and human alcoholics. Whether acamprosate can modulate executive functions that are impaired by chronic ethanol exposure is unknown. Here we explored the effects of acamprosate on an attentional set-shifting task, and tested whether these behavioral effects are correlated with modulation of glutamatergic synaptic transmission and intrinsic excitability of mPFC neurons. Methods: We induced alcohol dependence in mice via chronic intermittent ethanol (CIE) exposure in vapor chambers and measured changes in alcohol consumption in a limited access 2-bottle choice paradigm. Impairments of executive function were assessed in an attentional set-shifting task. Acamprosate was applied subchronically for 2 days during withdrawal before the final behavioral test. Alcohol-induced changes in cellular function of layer 5/6 pyramidal neurons, and the potential modulation of these changes by acamprosate, were measured using patch clamp recordings in brain slices. Results: Chronic ethanol exposure impaired cognitive flexibility in the attentional set-shifting task. Acamprosate improved overall performance and reduced perseveration. Recordings of mPFC neurons showed that chronic ethanol exposure increased use-dependent presynaptic transmitter release and enhanced postsynaptic N-methyl-D-aspartate receptor (NMDAR) function. Moreover, CIE-treatment lowered input resistance, and decreased the threshold and the afterhyperpolarization (AHP) of action potentials, suggesting chronic ethanol exposure also impacted membrane excitability of mPFC neurons. However, acamprosate treatment did not reverse these ethanol-induced changes cellular function. Conclusion: Acamprosate improved attentional control of ethanol exposed animals

Postnatal development of eupneic ventilation and metabolism in rats chronically exposed to moderate hyperoxia

PubMed Central

Bavis, Ryan W.; van Heerden, Eliza S.; Brackett, Diane G.; Harmeling, Luke H.; Johnson, Stephen M.; Blegen, Halward J.; Logan, Sarah; Nguyen, Giang N.; Fallon, Sarah C.

2014-01-01

Newborn rats chronically exposed to moderate hyperoxia (60% O2) exhibit abnormal respiratory control, including decreased eupneic ventilation. To further characterize this plasticity and explore its proximate mechanisms, rats were exposed to either 21% O2 (Control) or 60% O2 (Hyperoxia) from birth until studied at 3 – 14 days of age (P3 – P14). Normoxic ventilation was reduced in Hyperoxia rats when studied at P3, P4, and P6-7 and this was reflected in diminished arterial O2 saturations; eupneic ventilation spontaneously recovered by P13-14 despite continuous hyperoxia, or within 24 h when Hyperoxia rats were returned to room air. Normoxic metabolism was also reduced in Hyperoxia rats but could be increased by raising inspired O2 levels (to 60% O2) or by uncoupling oxidative phosphorylation within the mitochondrion (2, 4-dinitrophenol). In contrast, moderate increases in inspired O2 had no effect on sustained ventilation which indicates that hypoventilation can be dissociated from hypometabolism. The ventilatory response to abrupt O2 inhalation was diminished in Hyperoxia rats at P4 and P6-7, consistent with smaller contributions of peripheral chemoreceptors to eupneic ventilation at these ages. Finally, the spontaneous respiratory rhythm generated in isolated brainstem-spinal cord preparations was significantly slower and more variable in P3-4 Hyperoxia rats than in age-matched Controls. We conclude that developmental hyperoxia impairs both peripheral and central components of eupneic ventilatory drive. Although developmental hyperoxia diminishes metabolism as well, this appears to be a regulated hypometabolism and contributes little to the observed changes in ventilation. PMID:24703970

Eryptosis in lead-exposed workers.

PubMed

Aguilar-Dorado, Itzel-Citlalli; Hernández, Gerardo; Quintanar-Escorza, Martha-Angelica; Maldonado-Vega, María; Rosas-Flores, Margarita; Calderón-Salinas, José-Víctor

2014-12-01

Eryptosis is a physiological phenomenon in which old and damaged erythrocytes are removed from circulation. Erythrocytes incubated with lead have exhibited major eryptosis. In the present work we found evidence of high levels of eryptosis in lead exposed workers possibly via oxidation. Blood samples were taken from 40 male workers exposed to lead (mean blood lead concentration 64.8μg/dl) and non-exposed workers (4.2μg/dl). The exposure to lead produced an intoxication characterized by 88.3% less δ-aminolevulinic acid dehydratase (δALAD) activity in lead exposed workers with respect to non-lead exposed workers. An increment of oxidation in lead exposed workers was characterized by 2.4 times higher thiobarbituric acid-reactive substance (TBARS) concentration and 32.8% lower reduced/oxidized glutathione (GSH/GSSG) ratio. Oxidative stress in erythrocytes of lead exposed workers is expressed in 192% higher free calcium concentration [Ca(2+)]i and 1.6 times higher μ-calpain activity with respect to non-lead exposed workers. The adenosine triphosphate (ATP) concentration was not significantly different between the two worker groups. No externalization of phosphatidylserine (PS) was found in non-lead exposed workers (<0.1%), but lead exposed workers showed 2.82% externalization. Lead intoxication induces eryptosis possibly through a molecular pathway that includes oxidation, depletion of reduced glutathione (GSH), increment of [Ca(2+)], μ-calpain activation and externalization of PS in erythrocytes. Identifying molecular signals that induce eryptosis in lead intoxication is necessary to understand its physiopathology and chronic complications. Copyright © 2014 Elsevier Inc. All rights reserved.

Effects of maturation and acidosis on the chaos-like complexity of the neural respiratory output in the isolated brainstem of the tadpole, Rana esculenta

PubMed Central

Samara, Ziyad; Fiamma, Marie-Noëlle; Bautin, Nathalie; Ranohavimparany, Anja; Le Coz, Patrick; Golmard, Jean-Louis; Darré, Pierre; Zelter, Marc; Poon, Chi-Sang; Similowski, Thomas

2011-01-01

Human ventilation at rest exhibits mathematical chaos-like complexity that can be described as long-term unpredictability mediated (in whole or in part) by some low-dimensional nonlinear deterministic process. Although various physiological and pathological situations can affect respiratory complexity, the underlying mechanisms remain incompletely elucidated. If such chaos-like complexity is an intrinsic property of central respiratory generators, it should appear or increase when these structures mature or are stimulated. To test this hypothesis, we employed the isolated tadpole brainstem model [Rana (Pelophylax) esculenta] and recorded the neural respiratory output (buccal and lung rhythms) of pre- (n = 8) and postmetamorphic tadpoles (n = 8), at physiologic (7.8) and acidic pH (7.4). We analyzed the root mean square of the cranial nerve V or VII neurograms. Development and acidosis had no effect on buccal period. Lung frequency increased with development (P < 0.0001). It also increased with acidosis, but in postmetamorphic tadpoles only (P < 0.05). The noise-titration technique evidenced low-dimensional nonlinearities in all the postmetamorphic brainstems, at both pH. Chaos-like complexity, assessed through the noise limit, increased from pH 7.8 to pH 7.4 (P < 0.01). In contrast, linear models best fitted the ventilatory rhythm in all but one of the premetamorphic preparations at pH 7.8 (P < 0.005 vs. postmetamorphic) and in four at pH 7.4 (not significant vs. postmetamorphic). Therefore, in a lower vertebrate model, the brainstem respiratory central rhythm generator accounts for ventilatory chaos-like complexity, especially in the postmetamorphic stage and at low pH. According to the ventilatory generators homology theory, this may also be the case in mammals. PMID:21325645

The breeding behavior of Glyphoglossus molossus and the tadpoles of Glyphoglossus molossus and Calluella guttulata (Microhylidae).

PubMed

Altig, Ronald; Rowley, Jodi J L

2014-06-04

The breeding behavior of Glyphoglossus molossus is described from still and video images taken in Cambodia. These large, burrowing frogs follow the general theme of microhylids that deposit aquatic eggs: explosive breeding in ephemeral water and performing multiple amplectic dips to oviposit surface films of pigmented eggs. A portion of a clutch is released with each dip, a dip lasts for about 6 s, 200-300 eggs are released per dip, and about 5 s pass between dips. The ova have a dark black animal pole and yellow vegetal pole. Expanded datasets on the morphology of the tadpoles of Glyphoglossus from Vietnam and Calluella from Myanmar are presented. 

Mortality and toxin bioaccumulation in Bufo marinus following exposure to Cylindrospermopsis raciborskii cell extracts and live cultures.

PubMed

White, S H; Duivenvoorden, L J; Fabbro, L D; Eaglesham, G K

2007-05-01

Cylindrospermopsis raciborskii is a cyanobacterium responsible for the production of the toxin, cylindrospermopsin (CYN). Tadpoles of the cane toad Bufo marinus were exposed to freeze-thawed whole cell extracts or live cultures of C. raciborskii containing maximum CYN concentrations of 400 microg L-1 or 232 microg L-1, respectively. Exposure to live culture treatment solutions resulted in up to 66% mortality of B. marinus, whereas tadpoles exposed to whole cell extracts containing similar toxin concentrations survived. Decreases in relative growth rates and time spent for swimming were recorded from tadpoles during both types of exposure regimes. Bioconcentration of CYN was not evident following exposure to whole cell extracts containing extracellular toxin. In contrast exposure to live cultures, which contained cell-bound toxin, resulted in maximum average tissue concentrations of 895 microg free-CYN kg-1 fresh weight. This is the first investigation of C. raciborskii exposure effects and toxin bioaccumulation in the developmental stages of an amphibian.

Sub-chronic toxicity study in rats orally exposed to nanostructured silica

PubMed Central

2014-01-01

Background Synthetic Amorphous Silica (SAS) is commonly used in food and drugs. Recently, a consumer intake of silica from food was estimated at 9.4 mg/kg bw/day, of which 1.8 mg/kg bw/day was estimated to be in the nano-size range. Food products containing SAS have been shown to contain silica in the nanometer size range (i.e. 5 – 200 nm) up to 43% of the total silica content. Concerns have been raised about the possible adverse effects of chronic exposure to nanostructured silica. Methods Rats were orally exposed to 100, 1000 or 2500 mg/kg bw/day of SAS, or to 100, 500 or 1000 mg/kg bw/day of NM-202 (a representative nanostructured silica for OECD testing) for 28 days, or to the highest dose of SAS or NM-202 for 84 days. Results SAS and NM-202 were extensively characterized as pristine materials, but also in the feed matrix and gut content of the animals, and after in vitro digestion. The latter indicated that the intestinal content of the mid/high-dose groups had stronger gel-like properties than the low-dose groups, implying low gelation and high bioaccessibility of silica in the human intestine at realistic consumer exposure levels. Exposure to SAS or NM-202 did not result in clearly elevated tissue silica levels after 28-days of exposure. However, after 84-days of exposure to SAS, but not to NM-202, silica accumulated in the spleen. Biochemical and immunological markers in blood and isolated cells did not indicate toxicity, but histopathological analysis, showed an increased incidence of liver fibrosis after 84-days of exposure, which only reached significance in the NM-202 treated animals. This observation was accompanied by a moderate, but significant increase in the expression of fibrosis-related genes in liver samples. Conclusions Although only few adverse effects were observed, additional studies are warranted to further evaluate the biological relevance of observed fibrosis in liver and possible accumulation of silica in the spleen in the NM-202

Glucocorticosteroid hormone treatment of larval treefrogs increases infection by Alaria sp. trematode cercariae.

PubMed

Belden, L K; Kiesecker, J M

2005-06-01

In many amphibian species, an apparent increase has occurred in the prevalence of limb deformities caused by parasitic trematodes. We are interested in the role of environmental stressors in increasing these infections in amphibians. One mechanism by which environmental stressors could act to increase disease prevalence is to increase circulating levels of glucocorticosteroid hormones, which are released in response to stressors and can be immunosuppressive. In the present study, we treated gray treefroZg tadpoles (Hyla versicolor) with exogenous corticosterone, which is the main glucocorticosteroid "stress" hormone in amphibians. We then exposed treated tadpoles to Alaria sp. cercariae and scored the number of mesocercariae that successfully infected the tadpoles. In addition, we assayed one function of the immune response by counting the number of circulating eosinophilic granulocytes, which are thought to be important in immune responses to macroparasites. Tadpoles treated with exogenous corticosterone developed higher parasite loads than control tadpoles did, and they had lower numbers of circulating eosinophilic granulocytes. These results provide evidence of glucocorticosteroid-mediated immunosuppression in tadpoles that may help to explain apparent increases in the numbers of trematode-induced deformities in amphibian populations during recent decades.

Chronic periodontitis, inflammatory cytokines, and interrelationship with other chronic diseases.

PubMed

Cardoso, Elsa Maria; Reis, Cátia; Manzanares-Céspedes, Maria Cristina

2018-01-01

Periodontal diseases, such as chronic periodontitis, share common inflammatory risk factors with other systemic and chronic inflammatory disorders. Mucosal tissues, such as oral epithelia, are exposed to environmental stressors, such as tobacco and oral bacteria, that might be involved in promoting a systemic inflammatory state. Conversely, chronic disorders can also affect oral health. This review will summarize recent evidence for the interrelationship between chronic periodontitis and other prevalent chronic diseases such as cardiovascular diseases, diabetes, cancer and chronic respiratory diseases. The association with pregnancy is also included due to possible obstetric complications. We will focus on inflammatory cytokines such as TNF-alpha, IL-1, and IL-6, because they have been shown to be increased in patients with chronic periodontitis, in patients with chronic systemic diseases, and in patients with both chronic periodontitis and other chronic diseases. Therefore, an imbalance towards a proinflammatory immune response could underline a bidirectional link between chronic periodontitis and other chronic diseases. Finally, we highlight that a close coordination between dental and other health professionals could promote oral health and prevent or ameliorate other chronic diseases.

An epidemiologic study to screen for chronic myelocytic leukemia in war victims exposed to mustard gas.

PubMed Central

Ghanei, Mostafa; Vosoghi, Ali Akbar

2002-01-01

Chemical agents such as mustard gas (or sulfur mustard), which has alkylating characteristics, were used against Iranian combatants in the Iraq-Iran war. Previous studies have not shown a strong link between these chemical agents and the development of chronic myelocytic leukemia (CML). The purpose of this study was to evaluate the increased risk of CML development in Iranian soldiers exposed to mustard gas during the war. Based on a descriptive study of 2,500 cases with documented exposure to various chemical warfare agents, 665 patients had documented exposure to mustard gas. We screened the latter using the leukocyte alkaline phosphatase (LAP) test and performed further cytochemical studies on cases with positive results. From among the 665 cases with documented exposure to mustard gas, 9 cases had LAP scores < 20; 2 of these 9 cases had CML and a score of zero (0.3%). We detected cytogenetic abnormalities in 7 patients with low LAP scores and atypical lymphocytes of 5-11% in 40 patients. The risk ratio of CML developing in victims exposed to mustard gas (cutaneous or respiratory) may be higher in comparison with the normal population, although confounding factors (e.g., the possibility of exposure to combined chemical agents, excluding patients who did not manifest blisters) limited our results. Because the increased development of CML in young patients with a documented history of exposure to mustard gas cannot be disregarded, further studies are needed. PMID:12003756

Ferulic acid inhibits neuro-inflammation in mice exposed to chronic unpredictable mild stress.

PubMed

Liu, Ya-Min; Shen, Ji-Duo; Xu, Li-Ping; Li, Han-Bing; Li, Yu-Cheng; Yi, Li-Tao

2017-04-01

Ferulic acid is a hydroxycinnamic acid that widely presents in plant cell wall components. It has been demonstrated that ferulic acid can attenuate depressive-like behaviors in both forced swimming test and tail suspension test. Considering that depression is an inflammatory related mental disease, our present study was aimed to investigate the role of ferulic acid in the regulation of microglia activation, pro-inflammatory cytokines, nuclear factor kappa B (NF-κB) and nucleotide binding and oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome in mice exposed to chronic unpredictable mild stress (CUMS). Our results firstly showed that decreased sucrose preference and increased immobility time were completely reversed by administration with ferulic acid and fluoxetine for four weeks. Then, we found that CUMS significantly caused interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) up-regulation, microglia, NF-κB signaling and NLRP3 inflammasome activation in the prefrontal cortex. On the contrary, these activated inflammatory response induced by CUMS were reversed by ferulic acid and fluoxetine as well, suggesting that anti-inflammatory related mechanism was involved in the antidepressant-like effects of ferulic acid in stressed mice. Copyright © 2017 Elsevier B.V. All rights reserved.

Gill and lung ventilation responses to steady-state aquatic hypoxia and hyperoxia in the bullfrog tadpole.

PubMed

West, N H; Burggren, W W

1982-02-01

Gill ventilation frequency (fG), the pressure amplitude (PBC) and stroke volume (VS) of buccal ventilation cycles, the frequency of air breaths (fL), water flow over the gills (VW), gill oxygen uptake (MGO2), oxygen utilization (U), and heart frequency (fH) have been measured in unanaesthetized, air breathing Rana catesbeiana tadpoles (stage XVI-XIX). The animals were unrestrained except for ECG leads or cannulae, and were able to surface voluntarily for air breathing. They were subjected to aquatic normoxia, hyperoxia and three levels of aquatic hypoxia, and their respiratory responses recorded in the steady state. The experiments were performed at 20 +/- 0.5 degrees C. In hyperoxia there was an absence of air breathing, and fG, PBC and VW fell from the normoxic values, while U increased, resulting in no significant change in MGO2. Animals in normoxia showed a very low fL which increased in progressively more hypoxic states. VW increased from the normoxic value in mild hypoxia (PO2 = 96 +/- 2 mm Hg), but fell, associated with a reduction in PBC, in moderate (PO2 = 41 +/- 1 mm Hg) and severe (PO2 = 21 +/- 3 mm Hg) hypoxia in the presence of lung ventilation. Gill MGO2 was not significantly different from the normoxic value in mild hypoxia but fell in moderate hypoxia, while in severe hypoxia oxygen was lost to the ventilating water from the blood perfusing the gills. There was no significant change in fH from the normoxic value in either hypoxia or hyperoxia. These data indicate, that in the bimodally breathing bullfrog tadpole, aquatic PO2 exerts a strong control over both gill and lung ventilation. Furthermore, there is an interaction between gill and lung ventilation such that the onset of a high frequency of lung ventilation in moderate and severe hypoxia promotes a suppression of gill ventilation cycles.

Obstructive airway diseases in women exposed to biomass smoke.

PubMed

Ekici, Aydanur; Ekici, Mehmet; Kurtipek, Ercan; Akin, Ahmet; Arslan, Mesut; Kara, Türkan; Apaydin, Zeliha; Demir, Selma

2005-09-01

The majority of women living in rural areas in Turkey use biomass fuels for domestic energy and are exposed to high levels of indoor air pollution every day. The objective of this study was to compare the presence of chronic airway diseases (CAD) in two groups of nonsmoking women older than 40 years with (exposed group, n=397) and without a history of exposure to biomass cooking (liquid petroleum gas (LPG); control group, n=199), in 2002 in Kirikkale, Turkey. Detailed respiratory symptoms were collected with a standard questionnaire adapted from that of the British Medical Research Council. Exposure was calculated as the average hours spent daily for cooking multiplied by the number of years. CAD were defined as either chronic airway obstruction (CAO; (forced expiratory volume in 1s/forced vital capacity)<0.70), chronic bronchitis, or chronic bronchitis with CAO. The prevalence of CAD in the exposed group was found to be higher than that in the LPG group (28.5% vs. 13.6%, crude odds ratios (ORs) 2.5 (1.5--4.0), P=0.0001). The fraction of CAD attributed to exposure to biomass smoke after adjusting for possible confounding factors was 23.1% (95% confidence interval (CI) 13.4--33.2). Acute symptoms during exposure to biomass smoke were important predictors for the presence of CAD. Biomass smoke pollution is an important contributing factor in the development of CAD in nonsmoking women living in a rural area. The presence of acute symptoms during cooking in women in rural areas should signal to general practitioners the possibility of CAD.

In vivo time-lapse imaging of cell proliferation and differentiation in the optic tectum of Xenopus laevis tadpoles

PubMed Central

Bestman, Jennifer E.; Lee-Osbourne, Jane; Cline, Hollis T.

2012-01-01

We analyzed the function of neural progenitors in the developing CNS of Xenopus laevis tadpoles using in vivo time-lapse confocal microscopy to collect images through the tectum at intervals of 2 to 24 hours over 3 days. Neural progenitor cells were labeled with fluorescent protein reporters based on expression of endogenous Sox2 transcription factor. With this construct, we identified Sox2-expressing cells as radial glia and as a component of the progenitor pool of cells in the developing tectum that gives rise to neurons and other radial glia. Lineage analysis of individual radial glia and their progeny demonstrated that less than 10% of radial glia undergo symmetric divisions resulting in two radial glia, while the majority of radial glia divide asymmetrically to generate neurons and radial glia. Time-lapse imaging revealed the direct differentiation of radial glia into neurons. Although radial glia may guide axons as they navigate to superficial tectum, we find no evidence that radial glia function as a scaffold for neuronal migration at early stages of tectal development. Over three days, the number of labeled cells increased 20%, as the fraction of radial glia dropped and the proportion of neuronal progeny increased to approximately 60% of the labeled cells. Tadpoles provided with short-term visual enhancement generated significantly more neurons, with a corresponding decrease in cell proliferation. Together these results demonstrate that radial glial cells are neural progenitors in the developing optic tectum and reveal that visual experience increases the proportion of neurons generated in an intact animal. PMID:22113462

Bifurcations and stability of standing waves in the nonlinear Schrödinger equation on the tadpole graph

NASA Astrophysics Data System (ADS)

Noja, Diego; Pelinovsky, Dmitry; Shaikhova, Gaukhar

2015-07-01

We develop a detailed analysis of edge bifurcations of standing waves in the nonlinear Schrödinger (NLS) equation on a tadpole graph (a ring attached to a semi-infinite line subject to the Kirchhoff boundary conditions at the junction). It is shown in the recent work [7] by using explicit Jacobi elliptic functions that the cubic NLS equation on a tadpole graph admits a rich structure of standing waves. Among these, there are different branches of localized waves bifurcating from the edge of the essential spectrum of an associated Schrödinger operator. We show by using a modified Lyapunov-Schmidt reduction method that the bifurcation of localized standing waves occurs for every positive power nonlinearity. We distinguish a primary branch of never vanishing standing waves bifurcating from the trivial solution and an infinite sequence of higher branches with oscillating behavior in the ring. The higher branches bifurcate from the branches of degenerate standing waves with vanishing tail outside the ring. Moreover, we analyze stability of bifurcating standing waves. Namely, we show that the primary branch is composed by orbitally stable standing waves for subcritical power nonlinearities, while all nontrivial higher branches are linearly unstable near the bifurcation point. The stability character of the degenerate branches remains inconclusive at the analytical level, whereas heuristic arguments based on analysis of embedded eigenvalues of negative Krein signatures support the conjecture of their linear instability at least near the bifurcation point. Numerical results for the cubic NLS equation show that this conjecture is valid and that the degenerate branches become spectrally stable far away from the bifurcation point.

Growth and development of children prenatally exposed to telbivudine administered for the treatment of chronic hepatitis B in their mothers.

PubMed

Zeng, Huihui; Cai, Haodong; Wang, Ying; Shen, Ying

2015-04-01

We studied the growth and development of children prenatally exposed to telbivudine used to treat chronic hepatitis B virus (HBV) infection in their mothers. Maternal abnormalities during pregnancy and delivery and infant congenital anomalies, physical development status, developmental quotient (DQ), HBV vertical transmission status, and HBV vaccination outcomes of 54 infants were evaluated (2010-2013). No fetal abnormalities were observed during pregnancy or delivery. Postpartum, three infants (5.56%) had abnormalities: ankyloglossia, cutaneous hemangioma, and vaginal canal leak. Height and weight were within the normal range at birth and at 6 weeks, but were higher than the reference at 12 months (p<0.05). Body mass index increased gradually with age (p<0.05). DQ scores were normal (84.81%, 229/270) in 37 children (68.52%), abnormal or suspicious for a developmental delay (15.19%, 41/270) in 17 children (31.48%), and indicated a developmental delay (4.07%, 11/270) in seven children (12.96%). There were no significant differences in developmental delay between children prenatally exposed to telbivudine and controls (p>0.05). HBV vertical transmission was successfully blocked in all infants. The effective HBV vaccination rate was 98.15% (53/54). The growth and development of children prenatally exposed to telbivudine was normal, indicating that telbivudine treatment during pregnancy is safe and effective. Copyright © 2015. Published by Elsevier Ltd.

A novel reproductive mode in frogs: a new species of fanged frog with internal fertilization and birth of tadpoles.

PubMed

Iskandar, Djoko T; Evans, Ben J; McGuire, Jimmy A

2014-01-01

We describe a new species of fanged frog (Limnonectes larvaepartus) that is unique among anurans in having both internal fertilization and birth of tadpoles. The new species is endemic to Sulawesi Island, Indonesia. This is the fourth valid species of Limnonectes described from Sulawesi despite that the radiation includes at least 15 species and possibly many more. Fewer than a dozen of the 6455 species of frogs in the world are known to have internal fertilization, and of these, all but the new species either deposit fertilized eggs or give birth to froglets.

Work ability score of solvent-exposed workers.

PubMed

Furu, Heidi; Sainio, Markku; Hyvärinen, Hanna-Kaisa; Kaukiainen, Ari

2018-03-28

Occupational chronic solvent encephalopathy (CSE), characterized by neurocognitive dysfunction, often leads to early retirement. However, only the more severe cases are diagnosed with CSE, and little is known about the work ability of solvent-exposed workers in general. The aim was to study memory and concentration symptoms, work ability and the effect of both solvent-related and non-occupational factors on work ability, in an actively working solvent-exposed population. A questionnaire on exposure and health was sent to 3640 workers in four solvent-exposed fields, i.e. painters and floor-layers, boat builders, printers, and metal workers. The total number of responses was 1730. We determined the work ability score (WAS), a single question item of the Work Ability Index, and studied solvent exposure, demographic factors, Euroquest memory and concentration symptoms, chronic diseases, and employment status using univariate and multivariate analyses. The findings were compared to those of a corresponding national blue-collar reference population (n = 221), and a small cohort of workers with CSE (n = 18). The proportion of workers with memory and concentration symptoms was significantly associated with solvent exposure. The WAS of solvent-exposed workers was lower than that of the national blue-collar reference group, and the difference was significant in the oldest age group (those aged over 60). Solvent-exposed worker's WAS were higher than those of workers diagnosed with CSE. The WAS were lowest among painters and floor-layers, followed by metal workers and printers, and highest among boat builders. The strongest explanatory factors for poor work ability were the number of chronic diseases, age and employment status. Solvent exposure was a weak independent risk factor for reduced WAS, comparable to a level of high alcohol consumption. Even if memory and concentration symptoms were associated with higher solvent exposure, the effect of solvents on self

RESPIRATORY DAMAGE IN CHILDREN EXPOSED TO URBAN POLLUTION

EPA Science Inventory

Southwest Metropolitan Mexico City (SWMMC) children are chronically exposed to complex mixtures of air pollutants. In a cross-sectional arm of our study, we investigated the association between exposure to SWMMC atmosphere and nasal abnormalities, hyperinflation, and intersti...

Proteomic analysis of gastrocnemius muscle in rats with streptozotocin-induced diabetes and chronically exposed to fluoride.

PubMed

Lima Leite, Aline; Gualiume Vaz Madureira Lobo, Janete; Barbosa da Silva Pereira, Heloísa Aparecida; Silva Fernandes, Mileni; Martini, Tatiani; Zucki, Fernanda; Sumida, Dóris Hissako; Rigalli, Alfredo; Buzalaf, Marília Afonso Rabelo

2014-01-01

Administration of high doses of fluoride (F) can alter glucose homeostasis and lead to insulin resistance (IR). This study determined the profile of protein expression in the gastrocnemius muscle of rats with streptozotocin-induced diabetes that were chronically exposed to F. Male Wistar rats (60 days old) were randomly distributed into two groups of 18 animals. In one group, diabetes was induced through the administration of streptozotocin. Each group (D-diabetic and ND-non-diabetic) was further divided into 3 subgroups each of which was exposed to a different F concentration via drinking water (0 ppm, 10 ppm or 50 ppm F, as NaF). After 22 days of treatment, the gastrocnemius muscle was collected and submitted to proteomic analysis (2D-PAGE followed by LC-MS/MS). Protein functions were classified by the GO biological process (ClueGO v2.0.7+Clupedia v1.0.8) and protein-protein interaction networks were constructed (PSICQUIC, Cytoscape). Quantitative intensity analysis of the proteomic data revealed differential expression of 75 spots for ND0 vs. D0, 76 for ND10 vs.D10, 58 spots for ND50 vs. D50, 52 spots for D0 vs. D10 and 38 spots for D0 vs. D50. The GO annotations with the most significant terms in the comparisons of ND0 vs. D0, ND10 vs. D10, ND50 vs. D50, D0 vs. D10 and D0 vs. D50, were muscle contraction, carbohydrate catabolic processes, generation of precursor metabolites and energy, NAD metabolic processes and gluconeogenesis, respectively. Analysis of subnetworks revealed that, in all comparisons, proteins with fold changes interacted with GLUT4. GLUT4 interacting proteins, such as MDH and the stress proteins HSPB8 and GRP78, exhibited decreased expression when D animals were exposed to F. The presence of the two stress proteins indicates an increase in IR, which might worsen diabetes. Future studies should evaluate whether diabetic animals treated with F have increased IR, as well as which molecular mechanisms are involved.

Evidence for metabolic imbalance of vitamin A2 in wild fish chronically exposed to metals.

PubMed

Defo, Michel A; Pierron, Fabien; Spear, Philip A; Bernatchez, Louis; Campbell, Peter G C; Couture, Patrice

2012-11-01

In a recent study on indigenous yellow perch chronically exposed to metals, we reported a negative correlation between liver metal concentration and liver transcription levels of genes encoding for enzymes involved in the metabolism of retinoids. We therefore speculated that metals, and especially the non-essential metal Cd, could alter the metabolism of retinoids in wild fish. Thus the present field study investigates the impact of in situ metal exposure on retinoid storage. A total of 55 yellow perch (Perca flavescens) were sampled in six lakes representing a metal contamination gradient (8≤N≤10 per lake). Our results show that yellow perch from Cd-contaminated lakes had significantly higher concentrations of liver dehydroretinol and dehydroretinyl esters than did fish from reference lakes. However, the increase in retinyl ester stores with increasing Cd concentrations was quantitatively much more important than the increase in free dehydroretinol. As a result, a significant decrease in the percentage of hepatic free dehydroretinol with increasing renal Cd concentrations was observed. These results suggest that the enzymes and the binding proteins involved in vitamin A homeostasis are inhibited by the presence of Cd. Alternatively, the increase in tissue vitamin A (antioxidant) levels could serve to better counteract the oxidative stress engendered by Cd exposure. Overall our findings illustrate that vitamin A(2) homeostasis can be altered as a consequence of chronic exposure to low Cd concentrations. Thus, in the context of environmental risk assessment, the percentage of liver free dehydroretinol can be considered as a biomarker of for in situ Cd exposure. Copyright © 2012 Elsevier Inc. All rights reserved.

Risk and resilience trajectories in war-exposed children across the first decade of life.

PubMed

Halevi, Galit; Djalovski, Amir; Vengrober, Adva; Feldman, Ruth

2016-10-01

Although the effects of early-onset trauma on susceptibility to psychopathology are well-acknowledged, no study to date has followed risk and resilience trajectories in war-exposed young children over lengthy periods and charted predictors of individual pathways. In this prospective longitudinal study, we followed 232 children, including 148 exposed to repeated wartime trauma and 84 controls, at three time points: early childhood (1.5-5 years), middle childhood (5-8 years), and late childhood (9-11 years). Children were diagnosed at each time point and four trajectories defined: children exhibiting no pathology at any time point, those displaying early pathology that later remitted, those showing initial resilience followed by late pathology, and children presenting chronic pathology across the entire first decade. Maternal behavioral containment during trauma evocation and child social engagement during free play were observed in early childhood and maternal emotional distress self-reported across time. War-exposed children showed significantly higher rates of psychopathology, with 81% exhibiting pathology at some point during childhood. In middle childhood, exposed children displayed more posttraumatic stress disorders (PTSD), anxiety disorders, and attention-deficit/hyperactivity disorders (ADHD), and in late childhood more PTSD, conduct/oppositional defiant disorders, and ADHD. War-exposed children had more comorbid psychopathologies and number of comorbidities increased with age. Notably, war-exposure increased prevalence of chronic pathology by 24-fold. Maternal factors, including mother's uncontained style and emotional distress, increased risk for early and chronic psychopathology, whereas reduced child social engagement augmented risk for late pathology. Early-onset chronic stress does not heal naturally, and its effects appear to exacerbate over time, with trauma-exposed children presenting a more comorbid, chronic, and externalizing profile as they

Transcriptional regulators in the Hippo signaling pathway control organ growth in Xenopus tadpole tail regeneration.

PubMed

Hayashi, Shinichi; Ochi, Haruki; Ogino, Hajime; Kawasumi, Aiko; Kamei, Yasuhiro; Tamura, Koji; Yokoyama, Hitoshi

2014-12-01

The size and shape of tissues are tightly controlled by synchronized processes among cells and tissues to produce an integrated organ. The Hippo signaling pathway controls both cell proliferation and apoptosis by dual signal-transduction states regulated through a repressive kinase cascade. Yap1 and Tead, transcriptional regulators that act downstream of the Hippo signaling kinase cascade, have essential roles in regulating cell proliferation. In amphibian limb or tail regeneration, the local tissue outgrowth terminates when the correct size is reached, suggesting that organ size is strictly controlled during epimorphic organ-level regeneration. We recently demonstrated that Yap1 is required for the regeneration of Xenopus tadpole limb buds (Hayashi et al., 2014, Dev. Biol. 388, 57-67), but the molecular link between the Hippo pathway and organ size control in vertebrate epimorphic regeneration is not fully understood. To examine the requirement of Hippo pathway transcriptional regulators in epimorphic regeneration, including organ size control, we inhibited these regulators during Xenopus tadpole tail regeneration by overexpressing a dominant-negative form of Yap (dnYap) or Tead4 (dnTead4) under a heat-shock promoter in transgenic animal lines. Each inhibition resulted in regeneration defects accompanied by reduced cell mitosis and increased apoptosis. Single-cell gene manipulation experiments indicated that Tead4 cell-autonomously regulates the survival of neural progenitor cells in the regenerating tail. In amphibians, amputation at the proximal level of the tail (deep amputation) results in faster regeneration than that at the distal level (shallow amputation), to restore the original-sized tail with similar timing. However, dnTead4 overexpression abolished the position-dependent differential growth rate of tail regeneration. These results suggest that the transcriptional regulators in the Hippo pathway, Tead4 and Yap1, are required for general vertebrate

The breeding behaviour, advertisement call and tadpole of Limnonectes dabanus (Anura: Dicroglossidae).

PubMed

Rowley, Jodi J L; Le, Duong Thi Thuy; Hoang, Huy Duc; Altig, Ronald

2014-11-04

Fanged frogs (Limnonectes) are a group of dicroglossid frogs from Asia that often have reversed sexual dimorphism with larger males. Limnonectes dabanus is a poorly known species of fanged frog from forested habitats in southern Vietnam and eastern Cambodia. Adult males exhibit an extreme degree of megacephaly and possess bizarre head ornamentation. L. dabanus breeds in shallow, non-flowing or very slow-flowing pools, puddles, and drainage ditches. Eggs are laid as a widely spaced array, and the larvae have a morphology typical of pond-dwelling tadpoles. Although males of the species lack vocal sacs, they produce a low-pitched (0.4-0.6 kHz), single-note advertisement call that sounds like a drop of water falling into water. Given the spacing of calling males, presence of multiple females near breeding sites, and reversed sexual dimorphism, the mating system of L. dabanus may be an example of resource-defense polygyny, and the massive head of the male is likely used in male combat.

Long-Distance Signals Are Required for Morphogenesis of the Regenerating Xenopus Tadpole Tail, as Shown by Femtosecond-Laser Ablation

PubMed Central

Mondia, Jessica P.; Levin, Michael; Omenetto, Fiorenzo G.; Orendorff, Ryan D.; Branch, Mary Rose; Adams, Dany Spencer

2011-01-01

Background With the goal of learning to induce regeneration in human beings as a treatment for tissue loss, research is being conducted into the molecular and physiological details of the regeneration process. The tail of Xenopus laevis tadpoles has recently emerged as an important model for these studies; we explored the role of the spinal cord during tadpole tail regeneration. Methods and Results Using ultrafast lasers to ablate cells, and Geometric Morphometrics to quantitatively analyze regenerate morphology, we explored the influence of different cell populations. For at least twenty-four hours after amputation (hpa), laser-induced damage to the dorsal midline affected the morphology of the regenerated tail; damage induced 48 hpa or later did not. Targeting different positions along the anterior-posterior (AP) axis caused different shape changes in the regenerate. Interestingly, damaging two positions affected regenerate morphology in a qualitatively different way than did damaging either position alone. Quantitative comparison of regenerate shapes provided strong evidence against a gradient and for the existence of position-specific morphogenetic information along the entire AP axis. Conclusions We infer that there is a conduit of morphology-influencing information that requires a continuous dorsal midline, particularly an undamaged spinal cord. Contrary to expectation, this information is not in a gradient and it is not localized to the regeneration bud. We present a model of morphogenetic information flow from tissue undamaged by amputation and conclude that studies of information coming from far outside the amputation plane and regeneration bud will be critical for understanding regeneration and for translating fundamental understanding into biomedical approaches. PMID:21949803

Breeding habit of the toad Bufo coccifer in Costa Rica, with a description of the tadpole

USGS Publications Warehouse

McDiarmid, R.W.; Foster, M.S.

1981-01-01

The breeding habits of Bufo coccifer were studied in northwestern Costa Rica between 1971 and 1974. This species breeds during the rainy season, at least from May through August. Males chorus from areas of shallow water. Their calls resemble those of Mexican representatives of the species in pulse rate and duration, but are closer to those of other Costa Rican and Panamanian populations in dominant frequency. Thus, our data do not clearly support recognition of Bufo cycladen as a distinct species for the Mexican populations. Amplexus is axillary, and two strings of eggs are extruded simultaneously during oviposition. Tadpoles, described for the first time in this paper, are secretive and do not aggregate. Development to metamorphosis requires about 5 weeks.

Performance of a neuro-fuzzy model in predicting weight changes of chronic schizophrenic patients exposed to antipsychotics.

PubMed

Lan, T H; Loh, E W; Wu, M S; Hu, T M; Chou, P; Lan, T Y; Chiu, H-J

2008-12-01

Artificial intelligence has become a possible solution to resolve the problem of loss of information when complexity of a disease increases. Obesity phenotypes are observable clinical features of drug-naive schizophrenic patients. In addition, atypical antipsychotic medications may cause these unwanted effects. Here we examined the performance of neuro-fuzzy modeling (NFM) in predicting weight changes in chronic schizophrenic patients exposed to antipsychotics. Two hundred and twenty inpatients meeting DSMIV diagnosis of schizophrenia, treated with antipsychotics, either typical or atypical, for more than 2 years, were recruited. All subjects were assessed in the same study period between mid-November 2003 and mid-April 2004. The baseline and first visit's physical data including weight, height and circumference were used in this study. Clinical information (Clinical Global Impression and Life Style Survey) and genotype data of five single nucleotide polymorphisms were also included as predictors. The subjects were randomly assigned into the first group (105 subjects) and second group (115 subjects), and NFM was performed by using the FuzzyTECH 5.54 software package, with a network-type structure constructed in the rule block. A complete learned model trained from merged data of the first and second groups demonstrates that, at a prediction error of 5, 93% subjects with weight gain were identified. Our study suggests that NFM is a feasible prediction tool for obesity in schizophrenic patients exposed to antipsychotics, with further improvements required.

Label-free real-time imaging of myelination in the Xenopus laevis tadpole by in vivo stimulated Raman scattering microscopy

NASA Astrophysics Data System (ADS)

Hu, Chun-Rui; Zhang, Delong; Slipchenko, Mikhail N.; Cheng, Ji-Xin; Hu, Bing

2014-08-01

The myelin sheath plays an important role as the axon in the functioning of the neural system, and myelin degradation is a hallmark pathology of multiple sclerosis and spinal cord injury. Electron microscopy, fluorescent microscopy, and magnetic resonance imaging are three major techniques used for myelin visualization. However, microscopic observation of myelin in living organisms remains a challenge. Using a newly developed stimulated Raman scattering microscopy approach, we report noninvasive, label-free, real-time in vivo imaging of myelination by a single-Schwann cell, maturation of a single node of Ranvier, and myelin degradation in the transparent body of the Xenopus laevis tadpole.

Diazepam administration prevents testosterone decrease and lipofuscin accumulation in testis of mouse exposed to chronic noise stress.

PubMed

Ruffoli, R; Carpi, A; Giambelluca, M A; Grasso, L; Scavuzzo, M C; Giannessi F, F

2006-10-01

Lipofuscin is an autofluorescent and undegradable material, which accumulates in tissues during ageing and under different types of stress. Among these, oxidative stress represents a major trigger for lipofuscin formation. However, prolonged noise exposure is also an effective stressful stimuli. Diazepam may inhibit lipofuscinogenesis in liver and prevent the noise-induced reduction of the steroidogenesis in the adrenal gland. The aim of the study was to ascertain whether chronic noise exposure causes lipofuscin accumulation in mouse testis, and to evaluate the effects of diazepam administration. Eight-week old mice were either exposed for 6 weeks (6 h day(-1)) to white-noise (group A), or received diazepam (3 mg kg(-1), i.p.) before noise exposures (group B), while a further group was used as control (group C). Light fluorescence and transmission electron microscopy revealed lipofuscin in large amounts in the Leydig cells in mice of group A, which concomitantly had low serum testosterone levels; pre-treatment with diazepam occluded both effects. The present study indicates that: (i) chronic noise exposure causes lipofuscin accumulation at the level of the Leydig cells and a decrease in testosterone; (ii) all these effects are suppressed by pre-treatment with diazepam. As the Leydig cells represent the only cellular type of the interstitial testicular tissue having peripheral benzodiazepine receptors, these results could be explained by the capacity of the peripheral benzodiazepine receptors to prevent reactive oxygen species damage and to increase the resistance of these cells to oxidative stress.

Chronic psychosocial stressors and salivary biomarkers in emerging adults.

PubMed

Bergen, Andrew W; Mallick, Aditi; Nishita, Denise; Wei, Xin; Michel, Martha; Wacholder, Aaron; David, Sean P; Swan, Gary E; Reid, Mark W; Simons, Anne; Andrews, Judy A

2012-08-01

We investigated whole saliva as a source of biomarkers to distinguish individuals who have, and who have not, been chronically exposed to severe and threatening life difficulties. We evaluated RNA and DNA metrics, expression of 37 candidate genes, and cortisol release in response to the Trier Social Stress Test, as well as clinical characteristics, from 48 individuals stratified on chronic exposure to psychosocial stressors within the last year as measured by the Life Events and Difficulties Schedule. Candidate genes were selected based on their differential gene expression ratio in circulating monocytes from a published genome-wide analysis of adults experiencing different levels of exposure to a chronic stressor. In univariate analyses, we observed significantly decreased RNA integrity (RIN) score (P = 0.04), and reduced expression of glucocorticoid receptor-regulated genes (Ps < 0.05) in whole saliva RNA from individuals exposed to chronic stressors, as compared to those with no exposure. In those exposed, we observed significantly decreased BMI (P < 0.001), increased ever-smoking and increased lifetime alcohol abuse or dependence (P ≤ 0.03), and a reduction of cortisol release. In post hoc multivariate analyses including clinical and biospecimen-derived variables, we consistently observed significantly decreased expression of IL8 (Ps<0.05) in individuals exposed, with no significant association to RIN score. Alcohol use disorders, tobacco use, a reduced acute stress response and decreased salivary IL8 gene expression characterize emerging adults chronically exposed to severe and threatening psychosocial stressors. Copyright © 2011 Elsevier Ltd. All rights reserved.

Chronic respiratory effects of indoor formaldehyde exposure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krzyzanowski, M.; Quackenboss, J.J.; Lebowitz, M.D.

The relation of chronic respiratory symptoms and pulmonary function to formaldehyde (HCHO) in homes was studied in a sample of 298 children (6-15 years of age) and 613 adults. HCHO measurements were made with passive samplers during two 1-week periods. Data on chronic cough and phlegm, wheeze, attacks of breathlessness, and doctor diagnoses of chronic bronchitis and asthma were collected with self-completed questionnaires. Peak expiratory flow rates (PEFR) were obtained during the evenings and mornings for up to 14 consecutive days for each individual. Significantly greater prevalence rates of asthma and chronic bronchitis were found in children from houses withmore » HCHO levels 60-120 ppb than in those less exposed, especially in children also exposed to environmental tobacco smoke. In children, levels of PEFR decreased linearly with HCHO exposure, with the estimated decrease due to 60 ppb of HCHO equivalent to 22% of PEFR level in nonexposed children. The effects in asthmatic children exposed to HCHO below 50 ppb were greater than in healthy ones. The effects in adults were less evident: decrements in PEFR due to HCHO over 40 ppb were seen only in the morning, and mainly in smokers.« less

Effects of predatory fish on survival and behavior of larval gopher frogs (Rana capito) and Southern Leopard Frogs (Rana sphenocephala)

USGS Publications Warehouse

Gregoire, D.R.; Gunzburger, M.S.

2008-01-01

Southern Leopard Frogs, Rana sphenocephala, are habitat generalists occurring in virtually all freshwater habitats within their geographic range, whereas Gopher Frogs, Rana capito, typically breed in ponds that do not normally contain fish. To evaluate the potential for predation by fish to influence the distribution of these species, we conducted a randomized factorial experiment. We examined the survival rate and behavior of tadpoles when exposed to Warmouth Sunfish, Lepomis gulosus, Banded Sunfish, Enneacanthus obesus, and Eastern Mosquitofish, Gambusia holbrooki. We also conducted a choice experiment to examine the survival rate of the two species of tadpoles when a predator is given a choice of both species simultaneously. Lepomis gulosus consumed the most tadpoles and ate significantly more tadpoles of R. capito than R. sphenocephala. Gambusia holbrooki injured the most tadpoles, especially R. capito. Enneacanthus obesus did not have an effect on behavior or survival of either anuran species. Tadpoles of both anurans increased hiding when in the presence of L. gulosus and G. holbrooki, but a greater proportion of R. capito hid than did R. sphenocephala. Our results suggest that R. capito are more vulnerable to predation by fish than are R. sphenocephala. The introduction of fish may play a role in population declines of certain anurans breeding in normally fish-free wetlands, and even small fish, such as mosquitofish, may have significant negative effects on the tadpoles of R. capito. Copyright 2008 Society for the Study or Amphibians and Reptiles.

Changes in Serum Adiponectin in Mice Chronically Exposed to Inorganic Arsenic in Drinking Water.

PubMed

Song, Xuanbo; Li, Ying; Liu, Junqiu; Ji, Xiaohong; Zhao, Lijun; Wei, Yudan

2017-09-01

Cardiovascular disease and diabetes mellitus are prominent features of glucose and lipid metabolism disorders. Adiponectin is a key adipokine that is largely involved in glucose and lipid metabolism processes. A growing body of evidence suggests that chronic exposure to inorganic arsenic is associated with cardiovascular disease and diabetes mellitus. We hypothesized that arsenic exposure may increase the risk of cardiovascular disease and diabetes mellitus by affecting the level of adiponectin. In this study, we examined serum adiponectin levels, as well as serum levels of metabolic measures (including fasting blood glucose, insulin, total cholesterol, triglyceride, and high-density lipoprotein (HDL)-cholesterol) in C57BL/6 mice exposed to inorganic arsenic in drinking water (5 and 50 ppm NaAsO 2 ) for 18 weeks. Body mass and adiposity were monitored throughout the study. We found no significant changes in serum insulin and glucose levels in mice treated with arsenic for 18 weeks. However, arsenic exposure decreased serum levels of adiponectin, triglyceride, and HDL-cholesterol. Further, an inverse relationship was observed between urinary concentrations of total arsenic and serum levels of adiponectin. This study suggests that arsenic exposure could disturb the metabolism of lipids and increase the risk of cardiovascular disease by reducing the level of adiponectin.

Eryptosis in lead-exposed workers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aguilar-Dorado, Itzel-Citlalli; Hernández, Gerardo; Quintanar-Escorza, Martha-Angelica

Eryptosis is a physiological phenomenon in which old and damaged erythrocytes are removed from circulation. Erythrocytes incubated with lead have exhibited major eryptosis. In the present work we found evidence of high levels of eryptosis in lead exposed workers possibly via oxidation. Blood samples were taken from 40 male workers exposed to lead (mean blood lead concentration 64.8 μg/dl) and non-exposed workers (4.2 μg/dl). The exposure to lead produced an intoxication characterized by 88.3% less δ-aminolevulinic acid dehydratase (δALAD) activity in lead exposed workers with respect to non-lead exposed workers. An increment of oxidation in lead exposed workers was characterizedmore » by 2.4 times higher thiobarbituric acid-reactive substance (TBARS) concentration and 32.8% lower reduced/oxidized glutathione (GSH/GSSG) ratio. Oxidative stress in erythrocytes of lead exposed workers is expressed in 192% higher free calcium concentration [Ca{sup 2+}]{sub i} and 1.6 times higher μ-calpain activity with respect to non-lead exposed workers. The adenosine triphosphate (ATP) concentration was not significantly different between the two worker groups. No externalization of phosphatidylserine (PS) was found in non-lead exposed workers (< 0.1%), but lead exposed workers showed 2.82% externalization. Lead intoxication induces eryptosis possibly through a molecular pathway that includes oxidation, depletion of reduced glutathione (GSH), increment of [Ca{sup 2+}], μ-calpain activation and externalization of PS in erythrocytes. Identifying molecular signals that induce eryptosis in lead intoxication is necessary to understand its physiopathology and chronic complications. - Graphical abstract: Fig. 1. (A) Blood lead concentration (PbB) and (B) phosphatidylserine externalization on erythrocyte membranes of non-lead exposed (□) and lead exposed workers (■). Values are mean ± SD. *Significantly different (P < 0.001). - Highlights: • Erythrocytes of lead exposed

Respiratory-function changes in textile workers exposed to synthetic fibers.

PubMed

Valic, F; Zuskin, E

1977-01-01

The prevalence of respiratory symptoms and acute and chronic changes in ventilatory function were studied in three groups of textile workers: 68 workers with exposure to synthetic fibers only, 30 with previous exposure to cotton, and 77 with previous exposure to hemp. The prevalence of dyspnea, grade 3 to 4, was significantly lower (P less than .01) in workers with a history of exposure to synthetic fibers only than in those previously exposed to hemp or cotton. No case of byssinosis was found in any of the workers studied. Values in ventilatory-function tests (FEV 1.0, FVC and MEF 50%) were significantly reduced during the work shift on Monday and Thursday. The Monday MEF 50% preshift values were significantly lower than expected in all three groups of workers. A comparison of the 1963-1973 data on the 77 workers previously exposed to hemp showed a lower prevalence of most chronic respiratory symptoms and smaller acute FEV1.0 and FVC reductions when they worked with synthetic fibers (1973) than when they were exposed to hemp (1963).

Metabolomic profiling of brain tissues of mice chronically exposed to heroin.

PubMed

Li, Ren-Shi; Takeda, Tomoki; Ohshima, Takashi; Yamada, Hideyuki; Ishii, Yuji

2017-02-01

The chronic neurotoxicity of heroin on the nervous system is poorly understood. To address this issue, we comprehensively assessed the alteration of brain metabolomics caused by chronic heroin exposure and the withdrawal of heroin. Male C57BL/6J mice (n = 10) were given heroin (15 μmol/kg, i.p., twice a day) for 12 days while the withdrawal group received saline-treatment instead of heroin for the last two days. The control group received saline. We developed an UPLC-TOF/MS-based metabolomic approach to analyze the metabolites and carry out a metabolic pathway analysis in the brain. The major metabolites contributing to the discrimination were identified as amino acids, tricarboxylic-acid cycle intermediates, neurotransmitters, nucleotides and other compounds. A marked reduction in histidine and a slight but significant increase in phenylalanine and tryptophan were observed after heroin was withdrawn while the increased level of catecholamines was restored to baseline. Interestingly, N-acetylserotonin - a precursor of melatonin - was increased with the withdrawal of heroin while melatonin was markedly reduced along with the sub-chronic exposure to heroin. This shows that heroin disrupts not only the energy metabolism but also the biosynthesis of both catecholamines and melatonin in the mouse brain. Therefore, these substances are candidate biomarkers for chronic heroin-abuse. Copyright © 2016 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.

Tadpole-induced electroweak symmetry breaking and pNGB Higgs models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harnik, Roni; Howe, Kiel; Kearney, John

We investigate induced electroweak symmetry breaking (EWSB) in models in which the Higgs is a pseudo-Nambu-Goldstone boson (pNGB). In pNGB Higgs models, Higgs properties and precision electroweak measurements imply a hierarchy between the EWSB and global symmetry-breaking scales,more » $$v_H \\ll f_H$$. When the pNGB potential is generated radiatively, this hierarchy requires fine-tuning to a degree of at least $$\\sim v_H^2/f_H^2$$. We show that if Higgs EWSB is induced by a tadpole arising from an auxiliary sector at scale $$f_\\Sigma \\ll v_H$$, this tuning is significantly ameliorated or can even be removed. We present explicit examples both in Twin Higgs models and in Composite Higgs models based on $SO(5)/SO(4)$. For the Twin case, the result is a fully natural model with $$f_H \\sim 1$$ TeV and the lightest colored top partners at 2 TeV. These models also have an appealing mechanism to generate the scales of the auxiliary sector and Higgs EWSB directly from the scale $$f_H$$, with a natural hierarchy $$f_\\Sigma \\ll v_H \\ll f_H \\sim{\\rm TeV}$$. Finally, the framework predicts modified Higgs coupling as well as new Higgs and vector states at LHC13.« less

Tadpole-induced electroweak symmetry breaking and pNGB Higgs models

DOE PAGES

Harnik, Roni; Howe, Kiel; Kearney, John

2017-03-22

We investigate induced electroweak symmetry breaking (EWSB) in models in which the Higgs is a pseudo-Nambu-Goldstone boson (pNGB). In pNGB Higgs models, Higgs properties and precision electroweak measurements imply a hierarchy between the EWSB and global symmetry-breaking scales,more » $$v_H \\ll f_H$$. When the pNGB potential is generated radiatively, this hierarchy requires fine-tuning to a degree of at least $$\\sim v_H^2/f_H^2$$. We show that if Higgs EWSB is induced by a tadpole arising from an auxiliary sector at scale $$f_\\Sigma \\ll v_H$$, this tuning is significantly ameliorated or can even be removed. We present explicit examples both in Twin Higgs models and in Composite Higgs models based on $SO(5)/SO(4)$. For the Twin case, the result is a fully natural model with $$f_H \\sim 1$$ TeV and the lightest colored top partners at 2 TeV. These models also have an appealing mechanism to generate the scales of the auxiliary sector and Higgs EWSB directly from the scale $$f_H$$, with a natural hierarchy $$f_\\Sigma \\ll v_H \\ll f_H \\sim{\\rm TeV}$$. Finally, the framework predicts modified Higgs coupling as well as new Higgs and vector states at LHC13.« less

Proteomic Analysis of Gastrocnemius Muscle in Rats with Streptozotocin-Induced Diabetes and Chronically Exposed to Fluoride

PubMed Central

Lima Leite, Aline; Gualiume Vaz Madureira Lobo, Janete; Barbosa da Silva Pereira, Heloísa Aparecida; Silva Fernandes, Mileni; Martini, Tatiani; Zucki, Fernanda; Sumida, Dóris Hissako; Rigalli, Alfredo; Buzalaf, Marília Afonso Rabelo

2014-01-01

Administration of high doses of fluoride (F) can alter glucose homeostasis and lead to insulin resistance (IR). This study determined the profile of protein expression in the gastrocnemius muscle of rats with streptozotocin-induced diabetes that were chronically exposed to F. Male Wistar rats (60 days old) were randomly distributed into two groups of 18 animals. In one group, diabetes was induced through the administration of streptozotocin. Each group (D-diabetic and ND-non-diabetic) was further divided into 3 subgroups each of which was exposed to a different F concentration via drinking water (0 ppm, 10 ppm or 50 ppm F, as NaF). After 22 days of treatment, the gastrocnemius muscle was collected and submitted to proteomic analysis (2D-PAGE followed by LC-MS/MS). Protein functions were classified by the GO biological process (ClueGO v2.0.7+Clupedia v1.0.8) and protein-protein interaction networks were constructed (PSICQUIC, Cytoscape). Quantitative intensity analysis of the proteomic data revealed differential expression of 75 spots for ND0 vs. D0, 76 for ND10 vs.D10, 58 spots for ND50 vs. D50, 52 spots for D0 vs. D10 and 38 spots for D0 vs. D50. The GO annotations with the most significant terms in the comparisons of ND0 vs. D0, ND10 vs. D10, ND50 vs. D50, D0 vs. D10 and D0 vs. D50, were muscle contraction, carbohydrate catabolic processes, generation of precursor metabolites and energy, NAD metabolic processes and gluconeogenesis, respectively. Analysis of subnetworks revealed that, in all comparisons, proteins with fold changes interacted with GLUT4. GLUT4 interacting proteins, such as MDH and the stress proteins HSPB8 and GRP78, exhibited decreased expression when D animals were exposed to F. The presence of the two stress proteins indicates an increase in IR, which might worsen diabetes. Future studies should evaluate whether diabetic animals treated with F have increased IR, as well as which molecular mechanisms are involved. PMID:25180703

Lemna minor plants chronically exposed to ionising radiation: RNA-seq analysis indicates a dose rate dependent shift from acclimation to survival strategies.

PubMed

Van Hoeck, Arne; Horemans, Nele; Nauts, Robin; Van Hees, May; Vandenhove, Hildegarde; Blust, Ronny

2017-04-01

Ecotoxicological research provides knowledge on ionising radiation-induced responses in different plant species. However, the sparse data currently available are mainly extracted from acute exposure treatments. To provide a better understanding of environmental exposure scenarios, the response to stress in plants must be followed in more natural relevant chronic conditions. We previously showed morphological and biochemical responses in Lemna minor plants continuously exposed for 7days in a dose-rate dependent manner. In this study responses on molecular (gene expression) and physiological (photosynthetic) level are evaluated in L. minor plants exposed to ionising radiation. To enable this, we examined the gene expression profiles of irradiated L. minor plants by using an RNA-seq approach. The gene expression data reveal indications that L. minor plants exposed at lower dose rates, can tolerate the exposure by triggering acclimation responses. In contrast, at the highest dose rate tested, a high number of genes related to antioxidative defense systems, DNA repair and cell cycle were differentially expressed suggesting that only high dose rates of ionising radiation drive L. minor plants into survival strategies. Notably, the photosynthetic process seems to be unaffected in L. minor plants among the tested dose rates. This study, supported by our earlier work, clearly indicates that plants shift from acclimation responses towards survival responses at increasing dose rates of ionising radiation. Copyright © 2017 Elsevier B.V. All rights reserved.

Syndrome Analysis: Chronic Alcoholism in Adults.

ERIC Educational Resources Information Center

Pendorf, James E.

1990-01-01

Provides outline narrative of most possible outcomes of regular heavy alcohol use, regular alcohol abuse, or chronic alcoholism. A systems analysis approach is used to expose conditions that may result when a human organism is subjected to excessive and chronic alcohol consumption. Such an approach illustrates the detrimental effects which alcohol…

Modulation of GSH with exogenous agents leads to changes in glyoxalase 1 enzyme activity in VL-17A cells exposed to chronic alcohol plus high glucose.

PubMed

Kumar, S Mathan; Swaminathan, Kavitha; Clemens, Dahn L; Dey, Aparajita

2014-02-01

Gluthathione (GSH) is a major cellular antioxidant. The present study utilizing VL-17A cells exposed to chronic alcohol plus high glucose investigated the changes in oxidative stress, toxicity, and glyoxalase 1 activity as a detoxification pathway due to changes in GSH level through GSH supplementation with N-acetyl cysteine (NAC) or ursodeoxycholic acid (UDCA) and its depletion through buthionine sulfoximine (BSO) or diethyl maleate (DEM). Glyoxalase 1 plays an important role in detoxification of methylglyoxal which is formed as a precursor of advanced glycated end products formed due to high glucose mediated oxidative stress. Significant changes in glyoxalase 1 activity utilizing methylglyoxal or glyoxal as substrates occurred with NAC or UDCA or BSO or DEM supplementation in chronic alcohol plus high glucose treated VL-17A cells. NAC or UDCA administration in chronic alcohol plus high glucose treated VL-17A cells increased viability and decreased ROS levels, lipid peroxidation and 3-nitrotyrosine adduct formation. Similarly, GSH depletion with BSO or DEM had an opposite effect on the parameters in chronic alcohol plus high glucose treated VL-17A cells. In conclusion, modulation of GSH with NAC or UDCA or BSO or DEM leads to significant changes in oxidative stress, glyoxalase 1 enzyme activity and toxicity in chronic alcohol plus high glucose treated VL-17A cells.

The evaluation of serum total sialic acid and lipid-bound sialic acid levels in chronically exposed rats to 7,12-dimethylbenz(a)anthracene and fluoride

NASA Astrophysics Data System (ADS)

Oto, Gokhan; Ekin, Suat; Uyar, Hasan; Ozdemir, Hulya; Yıldız, Damla; Karakuş, Yagmur

2017-04-01

In this study, changes in serum total sialic acid (TSA) and lipid-bound sialic acid (LSA) levels were examined in chronically exposed rats to 7,12-dimethylbenz(a)anthracene (DMBA) and fluoride. This study demonstrated that the TSA, LSA levels increased more in DMBA-treated groups compared to the fluoride treated groups. The result obtained has shown that the harmful effect of DMBA which is also causing more cell membrane damage on human and animal health should be taken into consideration.

[Respiratory symptoms and obstructive ventilatory disorder in Tunisian woman exposed to biomass].

PubMed

Kwas, H; Rahmouni, N; Zendah, I; Ghedira, H

2017-04-01

In some Tunisian cities, especially semi-urbanized, the exposure to the smoke produced during combustion of the biomass, main source of pollution of indoor air, remains prevalent among non-smoking women. To assess the relationship between exposure to biomass smoke and the presence of obstructive ventilatory disorder in the non-smoking women in semi-urban areas of Tunisia. Cross etiological study, using a questionnaire, including 140 non-smoking women responsible for cooking and/or exposed during heating by traditional means with objective measurement of their respiratory functions. We found 81 women exposed to biomass for a period of≥20 hours-years and 59 unexposed women. Exposed women reported more respiratory symptoms namely exertional dyspnea and/or chronic cough than unexposed. Of the 140 women, 14 women have an FEV/FEV6<70% of which 13 are exposed to biomass. We found a correlation between respiratory symptoms and obstructive ventilatory disorder in exposed women. The air pollution inside the home during the traditional activities of cooking and/or heating is a respiratory risk factor for non-smoking women over the age of 30 years. Exposure to biomass smoke can cause chronic respiratory symptoms and persistent obstructive ventilatory disorder that can consistent with COPD. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Protein oxidative damage and heme oxygenase in sunlight-exposed human skin: roles of MAPK responses to oxidative stress.

PubMed

Akasaka, Emiko; Takekoshi, Susumu; Horikoshi, Yosuke; Toriumi, Kentarou; Ikoma, Norihiro; Mabuchi, Tomotaka; Tamiya, Shiho; Matsuyama, Takashi; Ozawa, Akira

2010-12-20

Oxidative stress derived from ultraviolet (UV) light in sunlight induces different hazardous effects in the skin, including sunburn, photo-aging and DNA mutagenesis. In this study, the protein-bound lipid peroxidation products 4-hydroxy-2-nonenal (HNE) and the oxidative DNA damage marker 8-hydroxy-2'-deoxyguanosine (8OHdG) were investigated in chronically sun-exposed and sun-protected human skins using immunohistochemistry. The levels of antioxidative enzymes, such as heme oxygenase 1 and 2, Cu/Zn-SOD, Mn-SOD and catalase, were also examined. Oxidative stress is also implicated in the activation of signal transduction pathways, such as mitogen-activated protein kinase (MAPK). Therefore, the expression and distribution of phosphorylated p38 MAPK, phosphorylated Jun N-terminal kinase (JNK) and phosphorylated extracellular signal-regulated kinase (ERK) were observed. Skin specimens were obtained from the surgical margins. Chronically sunlight-exposed skin samples were taken from the ante-auricular (n = 10) and sunlight-protected skin samples were taken from the post-auricular (n = 10). HNE was increased in the chronically sunlight-exposed skin but not in the sunlight-protected skin. The expression of heme oxygenase-2 was markedly increased in the sunlight-exposed skin compared with the sun-protected skin. In contrast, the intensity of immunostaining of Cu/Zn-SOD, Mn-SOD and catalase was not different between the two areas. Phosphorylated p38 MAPK and phosphorylated JNK accumulated in the ante-auricular dermis and epidermis, respectively. These data show that particular anti-oxidative enzymes function as protective factors in chronically sunlight-exposed human skin. Taken together, our results suggest (1) antioxidative effects of heme oxygenase-2 in chronically sunlight-exposed human skin, and that (2) activation of p38 MAPK may be responsible for oxidative stress.

Pulmonary granulomatous reaction: talc pneumoconiosis or chronic sarcoidosis?

PubMed Central

Tukiainen, P; Nickels, J; Taskinen, E; Nyberg, M

1984-01-01

A chronic pulmonary granulomatous reaction was associated with an almost identical clinical picture in two patients exposed to talc. In both patients lung biopsy showed the deposition of talc particles and a heavy granulomatous reaction. At the time of diagnosis the Kveim test result was negative in both patients, urinary calcium excretion was normal, and there were no extrapulmonary manifestations and no response to steroid treatment. These findings point against sarcoidosis. The serum angiotensin-converting enzyme level, however, was raised in both patients. It was concluded that the patient who was exposed to talc in the rubber industry had a true talc pneumoconiosis. The other patient, who was exposed to cosmetic talcum powder, suffered from chronic sarcoidosis with talc deposition in the lungs, since an enlarged axillar lymph node containing granulomatous inflammation was discovered after two years' follow up. These cases show that it may be extremely difficult to differentiate between chronic sarcoidosis and talc pneumoconiosis even after careful clinical and histological analysis. Images PMID:6691939

Choice of experimental venue matters in ecotoxicology studies: Comparison of a laboratory-based and an outdoor mesocosm experiment.

PubMed

Mikó, Zsanett; Ujszegi, János; Gál, Zoltán; Imrei, Zoltán; Hettyey, Attila

2015-10-01

The heavy application of pesticides and its potential effects on natural communities has attracted increasing attention to inadvertent impacts of these chemicals. Toxicologists conventionally use laboratory-based tests to assess lethal concentrations of pesticides. However, these tests often do not take into account indirect, interactive and long-term effects, and tend to ignore different rates of disintegration in the laboratory and under natural conditions. Our aim was to investigate the importance of the experimental venue for ecotoxicology tests. We reared tadpoles of the agile frog (Rana dalmatina) in the laboratory and in outdoor mesocosms and exposed them to three initial concentrations of a glyphosate-based herbicide (0, 2 and 6.5 mg a.e./L glyphosate), and to the presence or absence of caged predators (dragonfly larvae). The type of experimental venue had a large effect on the outcome: The herbicide was less lethal to tadpoles reared in outdoor mesocosms than in the laboratory. Further, while the herbicide had a negative effect on development time and on body mass in the laboratory, tadpoles exposed to the herbicide in mesocosms were larger at metamorphosis and developed faster in comparison to those reared in the absence of the herbicide. The effect of the herbicide on morphological traits of tadpoles also differed between the two venues. Finally, in the presence of the herbicide, tadpoles tended to be more active and to stay closer to the bottom of laboratory containers, while tadpole behaviour shifted in the opposite direction in outdoor mesocosms. Our results demonstrate major discrepancies between results of a classic laboratory-based ecotoxicity test and outcomes of an experiment performed in outdoor mesocosms. Consequently, the use of standard laboratory tests may have to be reconsidered and their benefits carefully weighed against the difficulties of performing experiments under more natural conditions. Tests validating experimentally estimated

Temporal analysis of oxidative effects on the pulmonary inflammatory response in mice exposed to cigarette smoke.

PubMed

Campos, Keila Karine Duarte; Manso, Rafaela Gontijo; Gonçalves, Evandro Guedes; Silva, Marcelo Eustáquio; de Lima, Wanderson Geraldo; Menezes, Cristiane Alves Silva; Bezerra, Frank Silva

2013-01-01

The most common factor related to the chronic obstructive pulmonary disease (COPD) development is the chronic smoking habit. Our study describes the temporal kinesis of pulmonary cellular influx through BALF analyses of mice acutely exposed to cigarette smoke (CS), the oxidative damage and antioxidative enzyme activities. Thirty-six mice (C57BL/6, 8weeks old, male) were divided in 6 groups: the control group (CG), exposed to ambient air, and the other 30 mice were exposed to CS. Mice exposed to CS presented, especially after the third day of exposure, different cellular subpopulations in BALF. The oxidative damage was significantly higher in CS exposed groups compared to CG. Our data showed that the evaluated inflammatory cells, observed after three days of CS exposure, indicate that this time point could be relevant to studies focusing on these cellular subpopulation activities and confirm the oxidative stress even in a short term CS exposure. Copyright © 2013 Elsevier Inc. All rights reserved.

Chronic respiratory effects of indoor formaldehyde exposure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krzyzanowski, M.; Quackenboss, J.J.; Lebowitz, M.D.

The relation of chronic respiratory symptoms and pulmonary function to formaldehyde (HCHO) in homes was studied in a sample of 298 children (6-15 years of age) and 613 adults. HCHO measurements were made with passive samplers two one-week periods. Data on chronic cough and phlegm, wheeze, attacks of breathlessness, and doctor diagnoses of chronic bronchitis and asthma were collected with self-completed questionnaires. Peak expiratory flow rates (PEFR) were obtained during the evenings and mornings for up to 14 consecutive days for each individual. Significantly greater prevalence rates of asthma and chronic bronchitis were found in children from houses with HCHOmore » levels 60-120 ppb than in those less exposed, especially in children also exposed to environmental tobacco smoke. In children, levels of PEFR linearly decreased with HCHO exposure, with estimated decrease due to 60 ppb of HCHO equivalent to 22% of PEFR level in nonexposed children.« less

Biomarker analysis of American toad (Anaxyrus americanus) ...

EPA Pesticide Factsheets

The objective of the current study was to use a biomarker-based approach to investigate the influence of atrazine exposure on American toad (Anaxyrus americanus) and grey tree frog (Hyla versicolor) tadpoles. Atrazine is one of the most frequently detected herbicides in environmental matrices throughout the United States. In surface waters, it has been found at concentrations from 0.04–2859 μg/L and thus presents a likely exposure scenario for non-target species such as amphibians. Studies have examined the effect of atrazine on the metamorphic parameters of amphibians, however, the data are often contradictory. Gosner stage 22–24 tadpoles were exposed to 0 (control), 10, 50, 250 or 1250 μg/L of atrazine for 48 h. Endogenous polar metabolites were extracted and analyzed using gas chromatography coupled with mass spectrometry. Statistical analyses of the acquired spectra with machine learning classification models demonstrated identifiable changes in the metabolomic profiles between exposed and control tadpoles. Support vector machine models with recursive feature elimination created a more efficient, non-parametric data analysis and increased interpretability of metabolomic profiles. Biochemical fluxes observed in the exposed groups of both A. americanus and H. versicolor displayed perturbations in a number of classes of biological macromolecules including fatty acids, amino acids, purine nucleosides, pyrimidines, and mono- and di-saccharides. Metabolomic

A multigene locus containing the Manx and bobcat genes is required for development of chordate features in the ascidian tadpole larva.

PubMed

Swalla, B J; Just, M A; Pederson, E L; Jeffery, W R

1999-04-01

The Manx gene is required for the development of the tail and other chordate features in the ascidian tadpole larva. To determine the structure of the Manx gene, we isolated and sequenced genomic clones from the tailed ascidian Molgula oculata. The Manx gene contains 9 exons and encodes both major and minor Manx mRNAs, which differ in the length of their 5' untranslated regions. The coding region of the single-copy bobcat gene, which encodes a DEAD-box RNA helicase, is embedded within the first Manx intron. The organization of the bobcat and Manx transcription units was determined by comparing genomic and cDNA clones. The Manx-bobcat gene locus has an unusual organization in which a non-coding first exon is alternatively spliced at the 5' end of two different mRNAs. The bobcat and Manx genes are expressed coordinately during oogenesis and embryogenesis, but not during spermatogenesis, in which bobcat mRNA accumulates independently of Manx mRNA. Similar to Manx, zygotic bobcat transcripts accumulate in the embryonic primordia responsible for generating chordate features, including the dorsal neural tube and notochord, are downregulated during embryogenesis in the tailless species Molgula occulta and are upregulated in M. occulta X M. oculata hybrids, which restore these chordate features. Antisense experiments indicate that zygotic bobcat expression is required for development of the same suite of chordate features as Manx. The results show that the Manx-bobcat gene complex has a role in the development of chordate features in ascidian tadpole larvae.

Genomic characterization of chronic lymphocytic leukemia (CLL) in radiation-exposed Chornobyl cleanup workers.

PubMed

Ojha, Juhi; Dyagil, Iryna; Finch, Stuart C; Reiss, Robert F; de Smith, Adam J; Gonseth, Semira; Zhou, Mi; Hansen, Helen M; Sherborne, Amy L; Nakamura, Jean; Bracci, Paige M; Gudzenko, Nataliya; Hatch, Maureen; Babkina, Nataliya; Little, Mark P; Chumak, Vadim V; Walsh, Kyle M; Bazyka, Dimitry; Wiemels, Joseph L; Zablotska, Lydia B

2018-05-02

Chronic lymphocytic leukemia (CLL) was the predominant leukemia in a recent study of Chornobyl cleanup workers from Ukraine exposed to radiation (UR-CLL). Radiation risks of CLL significantly increased with increasing bone marrow radiation doses. Current analysis aimed to clarify whether the increased risks were due to radiation or to genetic mutations in the Ukrainian population. A detailed characterization of the genomic landscape was performed in a unique sample of 16 UR-CLL patients and age- and sex-matched unexposed general population Ukrainian-CLL (UN-CLL) and Western-CLL (W-CLL) patients (n = 28 and 100, respectively). Mutations in telomere-maintenance pathway genes POT1 and ATM were more frequent in UR-CLL compared to UN-CLL and W-CLL (both p < 0.05). No significant enrichment in copy-number abnormalities at del13q14, del11q, del17p or trisomy12 was identified in UR-CLL compared to other groups. Type of work performed in the Chornobyl zone, age at exposure and at diagnosis, calendar time, and Rai stage were significant predictors of total genetic lesions (all p < 0.05). Tumor telomere length was significantly longer in UR-CLL than in UN-CLL (p = 0.009) and was associated with the POT1 mutation and survival. No significant enrichment in copy-number abnormalities at CLL-associated genes was identified in UR-CLL compared to other groups. The novel associations between radiation exposure, telomere maintenance and CLL prognosis identified in this unique case series provide suggestive, though limited data and merit further investigation.

Cold temperature blocks thyroid hormone-induced changes in lipid and energy metabolism in the liver of Lithobates catesbeianus tadpoles.

PubMed

Suzuki, Shunsuke; Awai, Koichiro; Ishihara, Akinori; Yamauchi, Kiyoshi

2016-01-01

Exposure of the American bullfrog Lithobates catesbeianus tadpoles to low temperature affects many biological processes including lipid metabolism and the thyroid hormone (TH) signaling pathway, resulting in arrest of TH-induced metamorphosis. To clarify what molecular events occur in this phenomenon, we investigated the glycerophospholipid and fatty acid (FA) compositions, the activities of mitochondrial enzymes and the transcript levels of related genes in the liver of control (26 °C) and cold-treated (4 °C) tadpoles with or without 5 nM 3,3',5-triiodothyronine (T3). Exposure to T3 decreased the tail height and polyunsaturation of FAs in the glycerophospholipids, and increased plasma glucose levels and transcript levels of primary TH-response genes including TH receptor, and some energy metabolic (cox4, srebp1 and fas) and FA chain elongase genes (elovl3 and elovl5). However, these T3-induced responses were abolished at 4 °C. Exposure to cold temperature enhanced plasma glucose, triglyceride and free FA levels, monounsaturation of FAs, mitochondrial enzymes activities (cytochrome c oxidase and carnitine palmitoyltransferase; U/g liver), with the upregulation of the genes involved in glycogenolysis (pygl), gluconeogenesis (pck1 and g6pc2), FA β-oxidation (acadl), and cholesterol uptake and synthesis (hmgcr, srebp2 and ldlr1), glycerophospholipids synthesis (pcyt1, pcyt2, pemt, and pparg), and FA monounsaturation (scd1) and chain elongation (elovl1 and elovl2). T3 had little effect on the cold-induced changes. Our study demonstrated that exposures to T3 and cold temperature exert different effects on lipid metabolism, resulting in changes in the FA composition in glycerophospholipids, and suggests that a cold-induced signal may block TH-signaling pathway around primary TH-response genes.

Localization of essential rhombomeres for respiratory rhythm generation in bullfrog tadpoles using a binary search algorithm: Rhombomere 7 is essential for the gill rhythm and suppresses lung bursts before metamorphosis.

PubMed

Duchcherer, Maryana; Baghdadwala, Mufaddal I; Paramonov, Jenny; Wilson, Richard J A

2013-12-01

Frog metamorphosis includes transition from water breathing to air breathing but the extent to which such a momentous change in behavior requires fundamental changes in the organization of the brainstem respiratory circuit is unknown. Here, we combine a vertically mounted isolated brainstem preparation, "the Sheep Dip," with a search algorithm used in computer science, to identify essential rhombomeres for generation of ventilatory motor bursts in metamorphosing bullfrog tadpoles. Our data suggest that rhombomere 7, which in mammals hosts the PreBötC (PreBötzinger Complex; the likely inspiratory oscillator), is essential for gill and buccal bursts. Whereas rhombomere 5, in close proximity to a brainstem region associated with the mammalian expiratory oscillator, is essential for lung bursts at both stages. Therefore, we conclude there is no rhombomeric translocation of respiratory oscillators in bullfrogs as previously suggested. In premetamorphic tadpoles, functional ablation of rhombomere 7 caused ectopic expression of precocious lung bursts, suggesting the gill oscillator suppresses an otherwise functional lung oscillator in early development. Copyright © 2013 Wiley Periodicals, Inc.

[Respiratory symptoms and obstructive ventilatory disorder in Tunisian woman exposed to biomass].

PubMed

Kwas, H; Rahmouni, N; Zendah, I; Ghédira, H

2017-06-01

In some Tunisian cities, especially semi-urbanized, the exposure to the smoke produced during combustion of the biomass, main source of pollution of indoor air, remains prevalent among non-smoking women. To assess the relationship between exposure to biomass smoke and the presence of obstructive ventilatory disorder in the non-smoking women in semi-urban areas of Tunisia. Cross etiological study, using a questionnaire, including 140 non-smoking women responsible for cooking and/or exposed during heating by traditional means with objective measurement of their respiratory functions. We found 81 women exposed to biomass for a period > or equal to 20 hours-years and 59 unexposed women. Exposed women reported more respiratory symptoms namely exertional dyspnea and/or chronic cough than unexposed. Of the 140 women, 14 women have an FEV/FEV6 <70 % of which 13 are exposed to biomass. We found a correlation between respiratory symptoms and obstructive ventilatory disorder in exposed women. The air pollution inside the home during the traditional activities of cooking and/or heating is a respiratory risk factor for non-smoking women over the age of 30 years. Exposure to biomass smoke can cause chronic respiratory symptoms and persistent obstructive ventilatory disorder that can be consistent with COPD. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Oxidative damage and histopathological changes in lung of rat chronically exposed to nicotine alone or associated to ethanol.

PubMed

Dhouib, H; Jallouli, M; Draief, M; Bouraoui, S; El-Fazâa, S

2015-12-01

Smoking is the most important preventable risk factor of chronic obstructive pulmonary disease and lung cancer. This study was designed to investigate oxidative damage and histopathological changes in lung tissue of rats chronically exposed to nicotine alone or supplemented with ethanol. Twenty-four male Wistar rats divided into three groups were used for the study. The nicotine group received nicotine (2.5mg/kg/day); the nicotine-ethanol group was given simultaneously same dose of nicotine plus ethanol (0.2g/kg/day), while the control group was administered only normal saline (1 ml/kg/day). The treatment was administered by subcutaneous injection once daily for a period of 18 weeks. Chronic nicotine administration alone or combined to ethanol caused a significant increase in malondialdehyde (MDA) level, superoxide dismutase (SOD) activity and catalase (CAT) activity in lung tissue compared to control rats suggesting an oxidative damage. However, these increases were mostly prominent in nicotine group. The histopathological examination of lung tissue of rats in both treated groups revealed many alterations in the pulmonary structures such as emphysema change (disappearance of the alveolar septa, increased irregularity and size of air sacs) and marked lymphocytic infiltration in perivascular and interstitial areas. However, the changes characterized in the nicotine group (pulmonary congestion, hemorrhage into alveoli and interstitial areas, edema) were more drastic than those observed in the nicotine-ethanol group, and they can be attributed to a significant degree of capillary endothelial permeability and microvascular leak. Conversely, the ethanol supplementation caused an appearance of fatty change and fibrosis in pulmonary tissue essentially due to a metabolism of ethanol. Finally, the lung damage illustrated in nicotine group was more severe than that observed in the nicotine-ethanol group. We conclude that the combined administration of nicotine and ethanol

Window contamination on Expose-R

NASA Astrophysics Data System (ADS)

Demets, R.; Bertrand, M.; Bolkhovitinov, A.; Bryson, K.; Colas, C.; Cottin, H.; Dettmann, J.; Ehrenfreund, P.; Elsaesser, A.; Jaramillo, E.; Lebert, M.; van Papendrecht, G.; Pereira, C.; Rohr, T.; Saiagh, K.

2015-01-01

Expose is a multi-user instrument for astrobiological and astrochemical experiments in space. Installed at the outer surface of the International Space Station, it enables investigators to study the impact of the open space environment on biological and biochemical test samples. Two Expose missions have been completed so far, designated as Expose-E (Rabbow et al. 2012) and Expose-R (Rabbow et al. this issue). One of the space-unique environmental factors offered by Expose is full-spectrum, ultraviolet (UV)-rich electromagnetic radiation from the Sun. This paper describes and analyses how on Expose-R, access of the test samples to Solar radiation degraded during space exposure in an unpredicted way. Several windows in front of the Sun-exposed test samples acquired a brown shade, resulting in a reduced transparency in visible light, UV and vacuum UV (VUV). Post-flight investigations revealed the discolouration to be caused by a homogenous film of cross-linked organic polymers at the inside of the windows. The chemical signature varied per sample carrier. No such films were found on windows from sealed, pressurized compartments, or on windows that had been kept out of the Sun. This suggests that volatile compounds originating from the interior of the Expose facility were cross-linked and photo-fixed by Solar irradiation at the rear side of the windows. The origin of the volatiles was not fully identified; most probably there was a variety of sources involved including the biological test samples, adhesives, plastics and printed circuit boards. The outer surface of the windows (pointing into space) was chemically impacted as well, with a probable effect on the transparency in VUV. The reported analysis of the window contamination on Expose-R is expected to help the interpretation of the scientific results and offers possibilities to mitigate this problem on future missions - in particular Expose-R2, the direct successor of Expose-R.

Clinical, parasitological and immunological features of canal cleaners hyper-exposed to Schistosoma mansoni in the Sudan

PubMed Central

SATTI, M Z; SULAIMAN, S M; HOMEIDA, M M A; YOUNIS, S A; GHALIB, H W

1996-01-01

The present work was a longitudinal study on Schistosoma mansoni infection in occupationally hyperexposed canal cleaners in the Sudan and the influence of therapy on the parasitological and humoral immune parameters. Chronically infected canal cleaners (n = 28) were more resistant to reinfection (Fisher's exact test, P < 0.05) than newly recruited canal cleaners (n = 17). Chronically infected canal cleaners had a significantly higher degree of Symmers' fibrosis (χ2 = 19.1, P < 0.0001), significantly larger portal vein diameter (P < 0.05) and enlarged spleen (χ2 = 4.2, P < 0.05) than recently infected, newly recruited canal cleaners. ELISA was used to detect IgG, IgA and IgM in response to whole worm homogenate (WWH) and cercarial homogenate (CH). Chronically infected canal cleaners had significantly higher IgG to WWH antigen than newly recruited canal cleaners and normally exposed individuals (P < 0.05), while both chronically infected and newly recruited canal cleaners had higher IgG levels to CH antigen than normally exposed individuals (P < 0.05). The newly recruited canal cleaners had a significantly higher IgM level to CH antigen than chronically infected canal cleaners (P < 0.05). The IgG level to WWH antigen increased significantly after treatment in newly recruited canal cleaners and normally exposed individuals (P < 0.05). The IgA level to CH antigen increased significantly after treatment in the chronically infected group (P < 0.05). Comparison of the serological parameters between the different study groups with regards to infection and treatment is discussed. PMID:9099926

Biological studies of swine exposed to 60-Hz electric fields. Volume 7. Neurology. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1985-12-01

Neurophysiological responses in three generations of miniature swine chronically exposed to a 30-kV/m, 60-Hz electric field have been assessed in a series of screening experiments. Results are presented from experiments on peripheral nerve function in parental (F/sub 0/) female swine at 100 days of gestation, and from experiments on synaptic transmission in first- and second-generation (F/sub 1/ and F/sub 2/) progeny at 6 weeks of age, all following chronic exposure to a 60-Hz electric field. In the several measures of peripheral nerve function examined, only two showed consistent differences between exposed and sham-exposed animals: C-fiber (but not B-fiber) conduction velocitymore » was decreased in nerve preparations from exposed swine, and recovery, as measured by the increase in amplitude of the compound action potential, was consistently, although not statistically, less in B- and C-fibers from exposed animals when compared to values for the sham-exposed controls. Although changes (increases or decreases) in various parameters of synaptic transmission were observed between exposed and sham-exposed groups, the differences were not consistent across experiments or generations. Only one measure of synaptic function showed a consistent difference throughout the studies: the conduction velocities of B and C components of the postsynaptic compound action potential were increased following electric-field exposure (statistically significant only in B-fibers of the F/sub 2/ generations). 7 refs., 60 figs., 17 tabs.« less

Chronic exposure to low frequency noise at moderate levels causes impaired balance in mice.

PubMed

Tamura, Haruka; Ohgami, Nobutaka; Yajima, Ichiro; Iida, Machiko; Ohgami, Kyoko; Fujii, Noriko; Itabe, Hiroyuki; Kusudo, Tastuya; Yamashita, Hitoshi; Kato, Masashi

2012-01-01

We are routinely exposed to low frequency noise (LFN; below 0.5 kHz) at moderate levels of 60-70 dB sound pressure level (SPL) generated from various sources in occupational and daily environments. LFN has been reported to affect balance in humans. However, there is limited information about the influence of chronic exposure to LFN at moderate levels for balance. In this study, we investigated whether chronic exposure to LFN at a moderate level of 70 dB SPL affects the vestibule, which is one of the organs responsible for balance in mice. Wild-type ICR mice were exposed for 1 month to LFN (0.1 kHz) and high frequency noise (HFN; 16 kHz) at 70 dB SPL at a distance of approximately 10-20 cm. Behavior analyses including rotarod, beam-crossing and footprint analyses showed impairments of balance in LFN-exposed mice but not in non-exposed mice or HFN-exposed mice. Immunohistochemical analysis showed a decreased number of vestibular hair cells and increased levels of oxidative stress in LFN-exposed mice compared to those in non-exposed mice. Our results suggest that chronic exposure to LFN at moderate levels causes impaired balance involving morphological impairments of the vestibule with enhanced levels of oxidative stress. Thus, the results of this study indicate the importance of considering the risk of chronic exposure to LFN at a moderate level for imbalance.

Chronic Exposure to Low Frequency Noise at Moderate Levels Causes Impaired Balance in Mice

PubMed Central

Tamura, Haruka; Ohgami, Nobutaka; Yajima, Ichiro; Iida, Machiko; Ohgami, Kyoko; Fujii, Noriko; Itabe, Hiroyuki; Kusudo, Tastuya; Yamashita, Hitoshi; Kato, Masashi

2012-01-01

We are routinely exposed to low frequency noise (LFN; below 0.5 kHz) at moderate levels of 60–70 dB sound pressure level (SPL) generated from various sources in occupational and daily environments. LFN has been reported to affect balance in humans. However, there is limited information about the influence of chronic exposure to LFN at moderate levels for balance. In this study, we investigated whether chronic exposure to LFN at a moderate level of 70 dB SPL affects the vestibule, which is one of the organs responsible for balance in mice. Wild-type ICR mice were exposed for 1 month to LFN (0.1 kHz) and high frequency noise (HFN; 16 kHz) at 70 dB SPL at a distance of approximately 10–20 cm. Behavior analyses including rotarod, beam-crossing and footprint analyses showed impairments of balance in LFN-exposed mice but not in non-exposed mice or HFN-exposed mice. Immunohistochemical analysis showed a decreased number of vestibular hair cells and increased levels of oxidative stress in LFN-exposed mice compared to those in non-exposed mice. Our results suggest that chronic exposure to LFN at moderate levels causes impaired balance involving morphological impairments of the vestibule with enhanced levels of oxidative stress. Thus, the results of this study indicate the importance of considering the risk of chronic exposure to LFN at a moderate level for imbalance. PMID:22768129

Failure of fallow deer (Dama dama) to develop chronic wasting disease when exposed to a contaminated environment and infected mule deer (Odocoileus hemionus).

PubMed

Rhyan, Jack C; Miller, Michael W; Spraker, Terry R; McCollum, Matt; Nol, Pauline; Wolfe, Lisa L; Davis, Tracy R; Creekmore, Lynn; O'Rourke, Katherine I

2011-07-01

We monitored a herd of fallow deer (Dama dama) for evidence of prion infection for 7 yr by periodic postmortem examination of animals from the herd. The fallow deer were exposed to the chronic wasting disease (CWD) agent from mule deer by living in a paddock considered contaminated with infectivity from its history of housing CWD infected deer and, after the first year of the study, by comingling with infected mule deer (Odocoileus hemionus). At least 8 of 12 mule deer serving as sentinels for prion transmission and 25 additional mule deer serving as sources of infectivity developed clinical CWD or were otherwise confirmed to be infected with CWD via lymphoid tissue immunohistochemistry (IHC). In contrast, none of the 41 exposed fallow deer showed clinical signs suggestive of CWD, IHC staining of disease-associated prion in lymphoid or brain tissues, or evidence of spongiform degeneration in sections of brain stem at the level of the obex when sampled 18 mo to 7 yr after entering the mule deer paddock. The absence of clinical disease and negative IHC results in fallow deer housed in the same contaminated paddock for up to 7 yr and almost continuously exposed to CWD-infected mule deer for up to 6 yr suggests a species barrier or other form of resistance preventing fallow deer infection by the CWD agent or delaying progression of the disease in this species.

Neurula rotation determines left-right asymmetry in ascidian tadpole larvae.

PubMed

Nishide, Kazuhiko; Mugitani, Michio; Kumano, Gaku; Nishida, Hiroki

2012-04-01

Tadpole larvae of the ascidian Halocynthia roretzi show morphological left-right asymmetry. The tail invariably bends towards the left side within the vitelline membrane. The structure of the larval brain is remarkably asymmetric. nodal, a conserved gene that shows left-sided expression, is also expressed on the left side in H. roretzi but in the epidermis unlike in vertebrates. We show that nodal signaling at the late neurula stage is required for stereotypic morphological left-right asymmetry at later stages. We uncover a novel mechanism to break embryonic symmetry, in which rotation of whole embryos provides the initial cue for left-sided expression of nodal. Two hours prior to the onset of nodal expression, the neurula embryo rotates along the anterior-posterior axis in a counterclockwise direction when seen in posterior view, and then this rotation stops when the left side of the embryo is oriented downwards. It is likely that epidermis monocilia, which appear at the neurula rotation stage, generate the driving force for the rotation. When the embryo lies on the left side, protrusion of the neural fold physically prevents it from rotating further. Experiments in which neurula rotation is perturbed by various means, including centrifugation and sandwiching between glass, indicate that contact of the left epidermis with the vitelline membrane as a consequence of neurula rotation promotes nodal expression in the left epidermis. We suggest that chemical, and not mechanical, signals from the vitelline membrane promote nodal expression. Neurula rotation is also conserved in other ascidian species.

A morphometric and molecular study of the apoptosis observed on tadpoles' tail explants under the exposition of triiodothyronine in different homeopathic dilutions.

PubMed

Guedes, José Roberto Pereira; Carrasco, Solange; Ferreira, Cláudia M; Bonamin, Leoni V; Goldenstein-Schainberg, Cláudia; Martins, Vanessa; Capelozzi, Vera L

2016-08-01

As a therapeutic system, homeopathy is supported by: i) similitude and experimentation in healthy individuals, ii) potentization. A challenge for researchers consists in looking for signals in water (or vehicle) to explain the storage of information in extremely high dilutions and the transfer of such information to the living systems. Anuran amphibian metamorphosis is controlled by thyroid hormones (TH), including the resorption of the tadpole tail. Apoptosis is a genetically regulated form of cell death that can be triggered by various extracellular and intracellular stimuli resulting in coordinated activation of a family of cysteine proteases called caspases. This study was blind and randomized. It performed in three stages: I) the identification of the most effective T3 homeopathic dilution to induce apoptotic reactions in Rana (Lithobates) catesbeianus tadpole tail explants stimulated by T3 in substantial, II) study of different controls and III) detection in explants under the action of the most effective dilution of T3, as established in Stage I. There was no statistically significant difference between tail macroscopic dimensions between the groups. T3 10cH decreased the expression of caspase 3/7 mRNA, in explants treated with T3 20 nM. The present experiment is in agreement with the hypothesis that T3, at a 10cH homeopathic dilution, changes the metamorphosis molecular network. Copyright © 2016 The Faculty of Homeopathy. Published by Elsevier Ltd. All rights reserved.

Effects of polychlorinated biphenyl 126 on green frog (Rana clamitans) and leopard frog (Rana pipiens) hatching success, development, and metamorphosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosenshield, M.L.; Jofre, M.B.; Karasov, W.H.

1999-11-01

Although increasing evidence links plana chlorinated hydrocarbons, such as polychlorinated biphenyls (PCBs), to decreases in survival and reproduction of fish, mammals, and birds near Green Bay, Wisconsin, and the Great Lakes, USA, relatively little is known of their bioaccumulation or of their possible effects in amphibians. The authors exposed embryos and larvae of two ranid species commonly occurring in the Green Bay ecosystem, the green frog (Rana clamitans) and the leopard frog (Rana pipiens), to PCB 126, a model coplanar PCB compound. Nominal concentrations ranged from 0.005 to 50 {micro}g/L, and exposure lasted through metamorphosis. Tissue concentrations of PCB 126more » in tadpoles that did not metamorphose by the end of the experiment ranged from 1.2 to 9,600 ng/g wet mass. No significant mortality of embryos occurred before hatching; however, survival of larvae was significantly reduced at the highest concentration for both species. Few deformities were observed, but the incidence of edema was significantly higher in tadpoles exposed to 50 {micro}g/L. Swimming speed and growth of tadpoles was also significantly reduced in this treatment. The percent of tadpoles that reached metamorphosis was significantly lower in green frogs at the highest concentration, and no leopard frogs survived past day 47 of the experiment in this treatment. At high concentrations, PCB 126 affected both ranid species; however, sublethal effects were not apparent for the parameters the authors measured at concentrations that occur in water in the Green Bay ecosystem.« less

Thermal manipulation during Pre and Post-Hatch on thermotolerance of male broiler chickens exposed to chronic heat stress.

PubMed

Zaboli, Gholam-Reza; Rahimi, Shaban; Shariatmadari, Farid; Torshizi, Mohammad Amir Karimi; Baghbanzadeh, Ali; Mehri, Mehran

2017-02-01

The aim of this study was to evaluate the effects of thermal manipulation (TM) during pre and post-hatch periods on thermotolerance of male broiler chickens exposed to chronic heat stress (CHS) during the finisher phase (34 ± 2°C, 6 h/day). Seven hundred fertile eggs of Ross 308 were assigned to the following groups: 1) control group incubated and housed in standard conditions, 2) pre-hatch treatment (PRE), the eggs were exposed to 39.5°C and 65% RH for 12 h, d from embryonic d 7 to 16 and after hatching the chicks where housed in standard conditions; 3 and 4) post-hatch TM at d 3 (PO3) and post-hatch TM at d 5 (PO5), which had the same incubation conditions as control and exposed to 36 to 38°C for 24 h at 3 and 5 days of age, respectively. TM in PRE group resulted in delay in the hatch time (6 h) along with reduction in body weight compared to control (P = 0.02). TM caused a significant reduction of facial surface temperature (FST) until d 28 (P < 0.02), but not significant during CHS. Body weight gain was suppressed in PO3 and PO5 groups at d 14 (P = 0.007) and compensated at d 28. However, TM led to higher BWG (P = 0.000) but lower FCR (P = 0.03) and mortality at the first week of CHS compared to control. European production efficiency index was higher in TM-treated chickens compared to control (P = 0.01). TM reduced the blood concentration of uric acid, total protein, T3, and T4 in which thyroid hormones in PO3 and PO5 treatments showed more reduction rather than other groups. In PRE group, chickens had lower abdominal fat pad than control (P = 0.0001). The relative weight of heart was decreased in TM groups (P = 0.001). It was concluded that TM may induce thermotolerance in growing broilers, possibly through the modification of physiological parameters of broilers especially during the first week of CHS. © 2016 Poultry Science Association Inc.

Sulfur dioxide-induced chronic bronchitis in beagle dogs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Greene, S.A.; Wolff, R.K.; Hahn, F.F.

This study was done to produce a model of chronic bronchitis. Twelve beagle dogs were exposed to 500 ppm sulfur dioxide (SO/sub 2/) for 2 h/d, 5d/wk for 21 wk and 4 dogs were sham-exposed to filtered ambient air for the same period. Exposure effects were evaluated by periodically examining the dogs using chest radiographs, pulmonary function, tracheal mucous clearance, and the cellular and soluble components of bronchopulmonary lavage fluids. Dogs were serially sacrificed after 13 and 21 wk of exposure and after 6 and 14 wk of recovery. Clinical signs produced in the SO/sub 2/-exposed dogs included mucoid nasalmore » discharge, productive cough, moist rales on auscultation, tonsilitis, and conjunctivitis. Chest radiographs revealed mild peribronchiolar thickening. Histopathology, tracheal mucous clearance measurements, and lavage cytology were consistent with a diagnosis of chronic bronchitis. It is concluded that repeated exposure to 500 ppm SO/sub 2/ for 21 wk produced chronic bronchitis in the beagle dog. Complete recovery occurred within 5 wk following cessation of SO/sub 2/ exposure. 43 references, 2 figures, 2 tables.« less

Hepatoprotective effect of silyamarin in individuals chronically exposed to hydrogen sulfide; modulating influence of TNF-α cytokine genetic polymorphism

PubMed Central

2013-01-01

Background and the purpose of the study Silymarin, a standardized extract of the milk thistle (Silybum marianum), is believed to exert some of its hepatoprotective effects though inhibition of free radicals and inflammation. In this study the effect of some pro- and anti-inflammatory cytokines and also antioxidant genes polymorphisms on the hepatoprotective effects of silymarin in the occupationally exposed individuals to hydrogen sulfide (H2S) in the sour natural gas refinery was investigated. Methods We genotyped seven polymorphisms in six genes reported by others as modifiers of oxidative stress (NQO1, mEPXH1, GSTT1 and GSTM1) and inflammation (TNF-α and TGF-β1) for an association in effect of decreasing in liver function tests (LFTs). The LFTs of 77 sour gas refinery workers were measured before and after administration of silymarin (140 mg, three times per day for 1 month). Results A significant reduction of blood AST, ALT and ALP was observed after 30 days of consumption (p < 0.001). The decreasing effect of silymarin on ALT in the subjects with high producer genotype (A allele carriers) was less than low producers. There were no significant associations between TGF-β1 and the studied genes of oxidative stress pathway and the effectiveness of silymarin. Conclusion This is the first report about the effectiveness of silymarin in the subjects exposed chronically to H2S. Meanwhile, the modulatory effect of TNF-α on the effectiveness of silymarin might be used for individualize therapy. PMID:23566372

Food availability determines the response to pond desiccation in anuran tadpoles.

PubMed

Enriquez-Urzelai, Urtzi; San Sebastián, Olatz; Garriga, Núria; Llorente, Gustavo A

2013-09-01

Food availability and pond desiccation are two of the most studied factors that condition amphibian metamorphosis. It is well known that, when food is abundant, organisms undergo metamorphosis early and when they are relatively large. The capability of anurans to accelerate their developmental rate in response to desiccation is also common knowledge. These two variables must act together in nature, since we know that, as a pond dries, the per capita resources decrease. We conduct an experiment to evaluate the effects of desiccation and food availability separately and in combination in tadpoles of the painted frog (Discoglossus pictus). We demonstrate that food deprivation leads to slow growth rates, which delay metamorphosis and produce smaller size and weight. The capability to accelerate metamorphosis when facing a drying pond is also confirmed, but, nevertheless, with factor interaction (when the pool is drying and resources are scarce) the capacity to respond to desiccation is lost. In addition, slow drying rates are shown to be stressful situations, but not enough to provoke a shortening of the larval period; in fact, the larval period becomes longer. We also demonstrate that the interaction of these factors changes the allometric relationship of different parts of the hind limb, which has implications for the biomechanics of jumping. Due to low mortality rates and an adequate response to both environmental factors, we expect D. pictus to have a great invasive potential in its new Mediterranean distribution area, where lots of temporary and ephemeral ponds are present.

Chronic Organic Solvent Exposure Changes Visual Tracking in Men and Women.

PubMed

de Oliveira, Ana R; Campos Neto, Armindo de Arruda; Bezerra de Medeiros, Paloma C; de Andrade, Michael J O; Dos Santos, Natanael A

2017-01-01

Organic solvents can change CNS sensory and motor function. Eye-movement analyses can be important tools when investigating the neurotoxic changes that result from chronic organic solvent exposure. The current research measured the eye-movement patterns of men and women with and without histories of chronic organic solvent exposure. A total of 44 volunteers between 18 and 41 years old participated in this study; 22 were men (11 exposed and 11 controls), and 22 were women (11 exposed and 11 controls). Eye movement was evaluated using a 250-Hz High-Speed Video Eye Tracker Toolbox (Cambridge Research Systems) via an image of a maze. Specific body indices of exposed and non-exposed men and women were measured with an Inbody 720 to determine whether the differences in eye-movement patterns were associated with body composition. The data were analyzed using IBM SPSS Statistics version 20.0.0. The results indicated that exposed adults showed significantly more fixations ( t = 3.82; p = 0.001; r = 0.51) and longer fixations ( t = 4.27; p = 0.001, r = 0.54) than their non-exposed counterparts. Comparisons within men (e.g., exposed and non-exposed) showed significant differences in the number of fixations ( t = 2.21; p = 0.04; r = 0.20) and duration of fixations ( t = 3.29; p = 0.001; r = 0.35). The same was true for exposed vs. non-exposed women, who showed significant differences in the number of fixations ( t = 3.10; p = 0.001; r = 0.32) and fixation durations ( t = 2.76; p = 0.01; r = 0.28). However, the results did not show significant differences between exposed women and men in the number and duration of fixations. No correlations were found between eye-movement pattern and body composition measures ( p > 0.05). These results suggest that chronic organic solvent exposure affects eye movements, regardless of sex and body composition, and that eye tracking contributes to the investigation of the visual information processing disorders acquired by workers exposed to

Differentiation of presumptive primordial germ cell (pPGC)-like cells in explants into PGCs in experimental tadpoles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ikenishi, K.; Okuda, T.; Nakazato, S.

1984-05-01

A single blastomere containing the ''germ plasm'' of 32-cell stage Xenopus embryos was cultured with (/sup 3/H)thymidine until the control embryos developed to the neurula stage. The explants, showing a spherical mass in which the nuclei of all cells were labeled, were implanted into the prospective place of presumptive primordial germ cells (pPGCs) in the endodermal cell mass of unlabeled host embryos of the neurula stage. Labeled PGCs as well as unlabeled, host PGCs were found in the genital ridges of experimental tadpoles. This indicates that the precursor of germ cells, corresponding to pPGCs in normal embryos of the neurulamore » stage, in the explants migrated to genital ridges just at the right moment to become PGCs, and suggests that the developmental process progressed normally, even in the explants, as far as the differentiation of pPGCs is concerned.« less

Thyroid hormones in chronic heat exposed men

NASA Astrophysics Data System (ADS)

Gertner, A.; Israeli, R.; Lev, A.; Cassuto, Y.

1983-03-01

Previous reports have indicated that thyroid gland activity, is depressed in the heat. Total thyroxine (T4) and triiodothyronine (T3) serum levels in 17 workers of the metal work shop at a plant near the Dead Sea and 8 workers in Beer Sheva, Israel were examined. The metal workshop of the plant near the Dead Sea is part of a large chemical plant. The one in Beer Sheva is part of a large construction company. Maintenance work, as well as metal work projects are performed in both workshops. During the work shifts, the workers of the Dead Sea plant were exposed to temperatures ranging from 30 36°C (May Oct.) and 14 21°C (Dec. Feb). In Beer Sheva the range was 25 32°C (June Sept.) and 10 17°C (Dec. Feb.). Total T4 was measured by competitive protein binding and total T3 by radioimmunoassay in blood drawn before work (0700) in July and January. In summer. T4 was higher and T3 was lower for both groups than in winter. The observed summer T3 decrease may result from depressed extrathyroidal conversion of T4 to T3. We conclude that the regulation of energy metabolism in hot climates may be related to extrathyroidal conversion of T4 to T3.

Memory Deficit Recovery after Chronic Vanadium Exposure in Mice.

PubMed

Folarin, Oluwabusayo; Olopade, Funmilayo; Onwuka, Silas; Olopade, James

2016-01-01

Vanadium is a transitional metal with an ability to generate reactive oxygen species in the biological system. This work was designed to assess memory deficits in mice chronically exposed to vanadium. A total of 132 male BALB/c mice (4 weeks old) were used for the experiment and were divided into three major groups of vanadium treated, matched controls, and animals exposed to vanadium for three months and thereafter vanadium was withdrawn. Animals were tested using Morris water maze and forelimb grip test at 3, 6, 9, and 12 months of age. The results showed that animals across the groups showed no difference in learning but had significant loss in memory abilities after 3 months of vanadium exposure and this trend continued in all vanadium-exposed groups relative to the controls. Animals exposed to vanadium for three months recovered significantly only 9 months after vanadium withdrawal. There was no significant difference in latency to fall in the forelimb grip test between vanadium-exposed groups and the controls in all age groups. In conclusion, we have shown that chronic administration of vanadium in mice leads to memory deficit which is reversible but only after a long period of vanadium withdrawal.

Chronic Vortioxetine Treatment Reduces Exaggerated Expression of Conditioned Fear Memory and Restores Active Coping Behavior in Chronically Stressed Rats.

PubMed

Hatherall, Lauren; Sánchez, Connie; Morilak, David A

2017-04-01

Stress is a risk factor for depression and anxiety disorders, disrupting neuronal processes leading to exaggerated fear and compromised coping behaviors. Current antidepressants are only partially effective. Vortioxetine, a novel multimodal antidepressant, is a serotonin transporter inhibitor; 5-HT3, 5-HT7, and 5-HT1D receptor antagonist; 5-HT1B partial agonist; and 5-HT1A agonist. We have shown that chronic dietary vortioxetine administration reversed stress-induced deficits in cognitive flexibility. In the present studies, we investigated the generality of vortioxetine's effects on other stress-related behavioral changes after different types of chronic stress. In experiment 1, rats were fear-conditioned by pairing a tone with footshock, then exposed to chronic plus acute prolonged stress. In experiment 2, rats were exposed to chronic unpredictable stress. In both experiments, beginning on day 4 of chronic stress, vortioxetine was given in the diet (24 mg/kg/d). In experiment 1, effects of vortioxetine were tested on stress-induced changes in retention and extinction of cue-conditioned fear, and in experiment 2, on coping behavior on the shock probe defensive burying test after chronic stress. Chronic stress exaggerated the expression of conditioned fear memory. Vortioxetine restored fear memory to control levels and rendered extinction in stressed rats comparable with that in controls. In experiment 2, chronic unpredictable stress caused a shift from active to passive coping behavior, and vortioxetine restored active coping. Vortioxetine reduced exaggerated expression of conditioned fear and restored adaptive coping behavior following 2 different types of chronic stress, adding to the evidence of its therapeutic potential in the management of depression and anxiety disorders. © The Author 2016. Published by Oxford University Press on behalf of CINP.

Pleiotropic Effects of Chronic Phorbol Ester Treatment to Improve Glucose Transport in Insulin-Resistant Cardiomyocytes.

PubMed

Viglino, Christelle; Khoramdin, Bahareh; Praplan, Guillaume; Montessuit, Christophe

2017-12-01

Stimulation of glucose transport is an important determinant of myocardial susceptibility to ischemia and reperfusion. Stimulation of glucose transport is markedly impaired in cardiomyocytes exposed to free fatty acids (FFA). Deactivation of the Focal Adhesion Kinase (FAK) by FFA contributes to glucose transport impairment, and could be corrected by chronic treatment with the phorbol ester TPA. However, TPA must have effects in addition to FAK reactivation to restore stimulated glucose transport. Chronic treatment with TPA improved basal and stimulated glucose transport in FFA-exposed, but not in control cardiomyocytes. Chronic FFA exposure induced the activation of PKCδ and PKCϵ. TPA markedly downregulated the expression of PKCα, PKCδ, and PKCϵ, suggesting that PKCδ or PKCϵ activation could contribute to inhibition of glucose transport by FFA. Rottlerin, a specific PKCδ inhibitor, improved glucose transport in FFA-exposed cardiomyocytes; and PKCδ was reduced in the particulate fraction of FFA + TPA-exposed cardiomyocytes. TPA also activated Protein Kinase D 1(PKD1) in FFA-exposed cardiomyocytes, as assessed by autophosphorylation of PKD1 on Y916. Pharmaceutical inhibition of PKD1 only partially prevented the improvement of glucose transport by TPA. Chronic TPA treatment also increased basal and stimulated glycolysis and favored accumulation of lipid droplets in FFA-exposed cardiomyocytes. In conclusion, basal and stimulated glucose transport in cardiomyocytes is reduced by chronic FFA exposure, but restored by concomitant treatment with a phorbol ester. The mechanism of action of phorbol esters may involve downregulation of PKCδ, activation of PKD1 and a general switch from fatty acid to glucose metabolism. J. Cell. Biochem. 9999: 4716-4727, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

An evaluation of 2,4-dichlorophenoxyacetic acid in the Amphibian Metamorphosis Assay and the Fish Short-Term Reproduction Assay.

PubMed

Coady, Katherine; Marino, Troy; Thomas, Johnson; Sosinski, Lindsay; Neal, Barbara; Hammond, Larry

2013-04-01

2,4-Dichlorophenoxyacetic acid (2,4-D) was evaluated in both the Amphibian Metamorphosis Assay (AMA) and the Fish Short Term Reproduction Assay (FSTRA). In the AMA, tadpoles were exposed to mean measured 2,4-D concentrations of 0 (water control), 0.273, 3.24, 38.0 and 113 mg acid equivalents (ae)/L for either seven or 21 days. In the FSTRA, fathead minnows were exposed to mean measured 2,4-D concentrations of 0 (water control), 0.245, 3.14, 34.0, and 96.5 mg ae/L for 21 days. The respective concentrations of 2,4-D were not overtly toxic to either Xenopus laevis tadpoles or fathead minnows (Pimephales promelas). In the AMA, there were no signs of either advanced or delayed development, asynchronous development, or significant histopathological effects of the thyroid gland among 2,4-D exposed tadpoles evaluated on either day seven or day 21 of the exposure. Therefore, following the AMA decision logic, 2,4-D is considered "likely thyroid inactive" in the AMA with a No Observable Effect Concentration (NOEC) of 113 mg ae 2,4-D/L. In the FSTRA, there were no significant differences between control and 2,4-D exposed fish in regard to fertility, wet weight, length, gonado-somatic indices, tubercle scores, or blood plasma concentrations of vitellogenin. Furthermore, there were no treatment-related histopathologic changes in the testes or ovaries in any 2,4-D exposed group. The only significant effect was a decrease in fecundity among fish exposed to 96.5 mg ae 2,4-D/L. The cause of the reduced fecundity at the highest concentration of 2,4-D tested in the assay was most likely due to a generalized stress response in the fish, and not due to a specific endocrine mode of action of 2,4-D. Based on fish reproduction, the NOEC in the FSTRA was 34.0 mg ae 2,4-D/L. Copyright © 2013 Elsevier Inc. All rights reserved.

A large, nationwide, longitudinal study of central nervous system diseases among Korean workers exposed to manganese.

PubMed

Yoon, Jin-Ha; Ahn, Yeon-Soon

2015-03-01

In occupational epidemiologic studies, the low incidence and chronic process of central nervous system (CNS) diseases has complicated the determination of the relationship between increased morbidity and manganese (Mn) exposure. Therefore, through this large cohort study, we evaluated CNS disease morbidity among Korean workers exposed to Mn Data were collected from Mn-associated specialized medical check-up 2000 and 2004 in Korea. The number of workers admitted to hospital because of clinically diagnosed CNS disease was analyzed in male workers exposed to Mn (n = 104,544). As a control reference population, 2% of Korean men were randomly selected and their hospital admission data were analyzed. For Mn-exposed workers, Standardized admission ratios (SARs) for CNS disease, as determined by ICD-10 classifications, were estimated in reference to the control population During follow up, 64 workers admitted because of CNS diseases. Chronic exposure to Mn (≥ 10 years) was significantly associated with the SAR (95% CI) of extrapyramidal and movement disorders (SAR: 2.03, 95% CI: 1.05-3.55), in particular, other extrapyramidal and movement disorders (SAR: 4.81, 95% CI: 1.29-12.32). Also borderline association (SAR = 4.88, 90% CI: 1.05-7.04) was noted for secondary Parkinsonism among workers with chronic Mn exposure. SARs (95% CI) for other degenerative nervous system diseases were significantly higher in Mn-exposed workers compared with the control population (SAR: 3.60, 95% CI: 1.16-8.40) CONCLUSION: In conclusion, Mn-exposed workers exhibited significantly elevated SARs for degenerative nervous system diseases and extrapyramidal and movement disorders, compared to the age-matched reference population, suggesting a relatedness with Mn exposure. Copyright © 2014 Elsevier Ltd. All rights reserved.

Quantitative proteomic analysis reveals proteins involved in the neurotoxicity of marine medaka Oryzias melastigma chronically exposed to inorganic mercury.

PubMed

Wang, Yuyu; Wang, Dazhi; Lin, Lin; Wang, Minghua

2015-01-01

Mercury is a ubiquitous environmental contaminant which exerts neurotoxicity upon animals. Nevertheless, the molecular mechanisms involved in inorganic mercury neurotoxicity are unknown. We investigated protein profiles of marine medaka, chronically exposed to mercuric chloride using two-dimensional difference gel electrophoresis (2D-DIGE) and matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry (MALDI-TOF-TOF MS) analysis. The mercury accumulation and ultrastructure were also examined in the brain. The results showed that mercury was significantly accumulated in the treated brain, and subsequently caused a noticeable damage. The comparison of 2D-DIGE protein profiles between the control and treatment revealed that 16 protein spots were remarkably altered in abundance, which were further submitted for MALDI-TOF-TOF MS analysis. The identified proteins indicated that inorganic mercury may cause neurotoxicity through the induction of oxidative stress, cytoskeletal assembly dysfunction and metabolic disorders. Thus, this study provided a basis for a better understanding of the molecular mechanisms involved in mercury neurotoxicity. Copyright © 2014 Elsevier Ltd. All rights reserved.

Biomechanical Changes in the Sclera of Monkey Eyes Exposed to Chronic IOP Elevations

PubMed Central

Girard, Michaël J. A.; Suh, J.-K. Francis; Bottlang, Michael; Burgoyne, Claude F.

2011-01-01

Purpose. To characterize scleral biomechanics in both eyes of eight monkeys in which chronic intraocular pressure (IOP) elevation was induced in one eye. Methods. Each posterior sclera was mounted on a pressurization apparatus, IOP was elevated from 5 to 45 mm Hg while the 3D displacements of the scleral surface were measured by speckle interferometry. Finite element (FE) models of each scleral shell were constructed that incorporated stretch-induced stiffening and multidirectionality of the collagen fibers. FE model predictions were then iteratively matched to experimental displacements to extract unique sets of scleral biomechanical properties. Results. For all eyes, the posterior sclera exhibited inhomogeneous, anisotropic, nonlinear biomechanical behavior. Biomechanical changes caused by chronic IOP elevation were complex and specific to each subject. Specifically: (1) Glaucomatous eyes in which the contralateral normal eyes displayed large modulus or thickness were less prone to biomechanical changes; (2) glaucomatous scleral modulus associated with an IOP of 10 mm Hg decreased (when compared with that of the contralateral normal) after minimal chronic IOP elevation; (3) glaucomatous scleral modulus associated with IOPs of 30 and 45 mm Hg increased (when compared with that of the contralateral normal) after moderate IOP elevation; and (4) FE-based estimates of collagen fiber orientation demonstrated no change in the glaucomatous eyes. Conclusions. Significant stiffening of the sclera follows exposure to moderate IOP elevations in most eyes. Scleral hypercompliance may precede stiffening or be a unique response to minimal chronic IOP elevation in some eyes. These biomechanical changes are likely to be the result of scleral extracellular matrix remodeling. PMID:21519033

In vivo evaluation of the potential neurotoxicity of aerosols released from mechanical stress of nano-TiO2 additived paints in mice chronically exposed by inhalation

NASA Astrophysics Data System (ADS)

Manixay, S.; Delaby, S.; Gaie-Levrel, F.; Wiart, M.; Motzkus, C.; Bencsik, A.

2017-06-01

Engineered Nanomaterials (ENM) provide technical and specific benefits due to their physical-chemical properties at the nanometer scale. For instance, many ENM are used to improve products in the building industry. Nanoscaled titanium dioxide (TiO2) is one of the most used ENM in this industry. Incorporated in different matrix, cement, glass, paints… TiO2 nanoparticles (NPs) provide the final product with anti-UV, air purification and self-cleaning properties, thanks to their photocatalytic activity. However, ageing processes of such products, as photocatalytic paints, during a mechanical stress have been shown to release TiO2 NPs from this matrix associated with sanding dust. Thus, workers who sand painted walls could be exposed to TiO2 NPs through inhalation. As inhalation may lead to a translocation of particulate matter to the brain via olfactory or trigeminal nerves, there is an urgent need for evaluating a potential neurotoxicity. In order to provide new knowledge on this topic, we developed a dedicated experimental set-up using a rodent model exposed via inhalation. The aerosol released from a mechanical stress of photocatalytic paints containing TiO2 NPs was characterized and coupled to an exposition chamber containing group of mice free to move and chronically exposed (2 hours per day for 5 days a week during 8 weeks).

Influence of Ribeiroia ondatrae (Trematoda: Digenea) infection on limb development and survival of northern leopard frogs (Rana pipiens): effects of host stage and parasite-exposure level

USGS Publications Warehouse

Schotthoefer, Anna M.; Koehler, Anson V.; Meteyer, Carol U.; Cole, Rebecca A.

2003-01-01

Recent evidence suggests that infection by larvae of the trematode Ribeiroia ondatrae accounts for a significant proportion of limb malformations currently observed in amphibian populations of North America. However, the effects of R. ondatrae infection on northern leopard frogs (Rana pipiens), one of the species most frequently reported with malformations, have not been adequately explored. Moreover, the risk factors associated with R. ondatrae-induced malformations have not been clearly identified. We examined the effects of timing of infection on tadpole survival and limb development. Rana pipiens tadpoles were individually exposed to R. ondatrae cercariae at the pre-limb-bud (Gosner stages 24 and 25), limb-bud (Gosner stages 27 and 28), or paddle (Gosner stages 31–33) stages of development and monitored through metamorphosis. The effects of infection were stage-specific. Infections acquired at the pre-limb-bud stage resulted in a high mortality rate (47.5–97.5%), whereas tadpoles infected at the limb-bud stage displayed a high malformation rate (16% overall), and the magnitude of effects increased with the level of exposure to cercariae. In contrast, infections acquired at the paddle stage had no effect on limb development or tadpole survival, which suggests that the timing of R. ondatrae infection in relation to the stage structure of tadpole populations in the wild is an important determinant of the degree to which populations are affected by R. ondatrae.

Early exposure to ultraviolet-B radiation decreases immune function later in life

PubMed Central

Ceccato, Emma; Cramp, Rebecca L.; Seebacher, Frank; Franklin, Craig E.

2016-01-01

Amphibians have declined dramatically worldwide. Many of these declines are occurring in areas where no obvious anthropogenic stressors are present. It is proposed that in these areas, environmental factors such as elevated solar ultraviolet-B (UV-B) radiation could be responsible. Ultraviolet-B levels have increased in many parts of the world as a consequence of the anthropogenic destruction of the ozone layer. Amphibian tadpoles are particularly sensitive to the damaging effects of UV-B radiation, with exposure disrupting growth and fitness in many species. Given that UV-B can disrupt immune function in other animals, we tested the hypothesis that early UV-B exposure suppresses the immune responses of amphibian tadpoles and subsequent juvenile frogs. We exposed Limnodynastes peronii tadpoles to sublethal levels of UV-B radiation for 6 weeks after hatching, then examined indices of immune function in both the tadpoles and the subsequent metamorphs. There was no significant effect of UV-B on tadpole leucocyte counts or on their response to an acute antigen (phytohaemagglutinin) challenge. However, early UV-B exposure resulted in a significant reduction in both metamorph leucocyte abundance and their response to an acute phytohaemagglutinin challenge. These data demonstrate that early UV-B exposure can have carry-over effects on later life-history traits even if the applied stressor has no immediately discernible effect. These findings have important implications for our understanding of the effects of UV-B exposure on amphibian health and susceptibility to diseases such as chytridiomycosis. PMID:27668081

Tadpole-shaped lateralized parietal atretic cephalocele associated with an ipsilateral lacrimal gland fistula and schizencephalic clefts.

PubMed

Murakami, Nobuya; Morioka, Takato; Suzuki, Satoshi O; Mukae, Nobutaka; Hashiguchi, Kimiaki; Iihara, Koji

2017-02-01

Parietal atretic cephalocele (AC) and its associated intracranial venous anomalies, such as vertical embryonic positioning of the straight sinus (VEP of SS), have, in previous reports, been exclusively restricted to the midline. We report a patient with lateralized parietal AC on the right side. The AC was in the shape of a tadpole, with a large head and a long tail, extending to the proximity of the right external canthus, where a lacrimal gland fistula was observed. The superior sagittal sinus and VEP of SS were also displaced to the right side, although the sagittal suture was located at the midline. Schizencephalic clefts in the right posterior cortex were also observed. The parietal AC, which was initially located in the midline, could conceivably have been displaced to the right side by other developmental processes. However, the relationship between lateralized AC and associated multiple anomalies on the ipsilateral side is difficult to explain monogenetically. Our case study indicates that AC might have a broader spectrum of clinical symptoms than was once thought to be the case.

The lateral line system in anuran tadpoles: neuromast morphology, arrangement, and innervation.

PubMed

Quinzio, Silvia; Fabrezi, Marissa

2014-08-01

Anuran larvae have been classified into four morphological types which reflect intraordinal macroevolution. At present, complete characterizations of the lateral line system are only available for Xenopus laevis (Type I) and Discoglossus pictus (Type III). We analyzed the morphology, arrangement, and innervation of neuromasts related to the anterodorsal and anteroventral lateral line nerves in 10 anuran species representing Types I, II, and IV with the aim of interpreting the existing variation and discussing the evolution of the lateral line in anuran larvae. We found: (1) the presence of two orbital and three mandibular neuromast lines in all anuran larvae studied, (2) the ventral arrangement of mandibular neuromast lines appears to have evolved convergently in Larval Types I and II, and the lateroventral arrangement of mandibular lines of neuromasts appears to have evolved in Larval Types III and IV; (3) interspecific variation in the organization, size, and number of sensory cells per neuromast within the lines; and (4) the supralabial extension of the Angular line in Lepidobatrachus spp. and the tentacular location of the Oral neuromasts in X. laevis are concomitant with their particular morphologies. Based on the variation described we find that the lateral line system in anuran larvae seems to have been maintained without significant changes, with the exception of Lepidobatrachus spp. and Xenopus. These unique features added to other of Lepidobatrachus tadpoles are sufficient to propose a new Larval Type (V). Copyright © 2014 Wiley Periodicals, Inc.

Memory Deficit Recovery after Chronic Vanadium Exposure in Mice

PubMed Central

Folarin, Oluwabusayo; Olopade, Funmilayo; Onwuka, Silas; Olopade, James

2016-01-01

Vanadium is a transitional metal with an ability to generate reactive oxygen species in the biological system. This work was designed to assess memory deficits in mice chronically exposed to vanadium. A total of 132 male BALB/c mice (4 weeks old) were used for the experiment and were divided into three major groups of vanadium treated, matched controls, and animals exposed to vanadium for three months and thereafter vanadium was withdrawn. Animals were tested using Morris water maze and forelimb grip test at 3, 6, 9, and 12 months of age. The results showed that animals across the groups showed no difference in learning but had significant loss in memory abilities after 3 months of vanadium exposure and this trend continued in all vanadium-exposed groups relative to the controls. Animals exposed to vanadium for three months recovered significantly only 9 months after vanadium withdrawal. There was no significant difference in latency to fall in the forelimb grip test between vanadium-exposed groups and the controls in all age groups. In conclusion, we have shown that chronic administration of vanadium in mice leads to memory deficit which is reversible but only after a long period of vanadium withdrawal. PMID:26962395

Neurocognitive screening of lead-exposed andean adolescents and young adults.

PubMed

Counter, S Allen; Buchanan, Leo H; Ortega, Fernando

2009-01-01

This study was designed to assess the utility of two psychometric tests with putative minimal cultural bias for use in field screening of lead (Pb)-exposed Ecuadorian Andean workers. Specifically, the study evaluated the effectiveness in Pb-exposed adolescents and young adults of a nonverbal reasoning test standardized for younger children, and compared the findings with performance on a test of auditory memory. The Raven Coloured Progressive Matrices (RCPM) was used as a test of nonverbal intelligence, and the Digit Span subtest of the Wechsler IV intelligence scale was used to assess auditory memory/attention. The participants were 35 chronically Pb-exposed Pb-glazing workers, aged 12-21 yr. Blood lead (PbB) levels for the study group ranged from 3 to 86 microg/dl, with 65.7% of the group at and above 10 microg/dl. Zinc protoporphyrin heme ratios (ZPP/heme) ranged from 38 to 380 micromol/mol, with 57.1% of the participants showing abnormal ZPP/heme (>69 micromol/mol). ZPP/heme was significantly correlated with PbB levels, suggesting chronic Pb exposure. Performance on the RCPM was less than average on the U.S., British, and Puerto Rican norms, but average on the Peruvian norms. Significant inverse associations between PbB/ZPP concentrations and RCPM standard scores using the U.S., Puerto Rican, and Peruvian norms were observed, indicating decreasing RCPM test performance with increasing PbB and ZPP levels. RCPM scores were significantly correlated with performance on the Digit Span test for auditory memory. Mean Digit Span scale score was less than average, suggesting auditory memory/attention deficits. In conclusion, both the RCPM and Digit Span tests were found to be effective instruments for field screening of visual-spatial reasoning and auditory memory abilities, respectively, in Pb-exposed Andean adolescents and young adults.

Irritable bowel syndrome and chronic fatigue 3 years after acute giardiasis: historic cohort study.

PubMed

Wensaas, Knut-Arne; Langeland, Nina; Hanevik, Kurt; Mørch, Kristine; Eide, Geir Egil; Rortveit, Guri

2012-02-01

Giardia lamblia is a common cause of gastroenteritis worldwide, but there is limited knowledge about the long-term complications. To estimate the relative risk of irritable bowel syndrome (IBS) and chronic fatigue 3 years after acute giardiasis. Controlled historic cohort study with 3 years' follow-up. Data collected by mailed questionnaire. Waterborne outbreak of giardiasis in the city of Bergen, Norway. 817 patients exposed to Giardia lamblia infection verified by detection of cysts in stool samples and 1128 matched controls. IBS and chronic fatigue. The prevalence of IBS in the exposed group was 46.1%, compared with 14.0% in the control group, and the adjusted RR=3.4 (95% CI 2.9 to 3.8). Chronic fatigue was reported by 46.1% of the exposed group and 12.0% of the controls, the adjusted RR was 4.0 (95% CI 3.5 to 4.5). IBS and chronic fatigue were associated and the RR for the exposed group of having a combination of the two outcomes was 6.8 (95% CI 5.3 to 8.5). The RR was also increased for having just one of the two syndromes, 1.8 for IBS (95% CI 1.4 to 2.3) and 2.2 for chronic fatigue (95% CI 1.7 to 2.8). Infection with Giardia lamblia in a non-endemic area was associated with a high prevalence of IBS and chronic fatigue 3 years after acute illness, and the risk was significantly higher than in the control group. This shows that the potential consequences of giardiasis are more serious than previously known. Further studies are needed, especially in areas where giardiasis is endemic.

Influence of chronic exposure to cold environment on thyroid gland function in rabbits.

PubMed

Mustafa, S; Elgazzar, A

2014-07-01

Chronic exposure to cold can affect the thyroid gland. However, the effect on thyroid gland perfusion images and the ratio between thyroid hormones secretion were not addressed in any previous study. The present study investigates the effects of chronic cold exposure on thyroid gland function using radionuclide tracer and thyroid hormones secretion concentration. New Zealand white rabbits weighing approximately 1.8-2 kg were kept in a cold room (4°C) for 7 weeks. Thyroid scintigraphy was performed for cold exposed rabbits and a control rabbit group. Each rabbit was injected with 115 MBq (3.1 mCi) technetium-99m pertechnetate (99mTc pertechnetate). Studies were performed using Gamma camera equipped with a low energy, high resolution, pinhole collimator interfaced with a computer. Static images were acquired 20 min after administration of the radiotracer. Rabbits chronically exposed to cold had less body weights than control. Thyroid gland uptake is higher in rabbits chronically exposed to cold than controls using radionuclide perfusion study. The increase was proportional to the time period, so the increase after 7 weeks was greater than 5 weeks. There is also an increase in free triiodothyronine (FT3) and a decrease in free thyroxine (FT4) values. Our results indicate that thyroid gland uptake is higher in rabbits chronically exposed to cold than control and the increase was proportional to the duration. The decrease in rabbit body weights may be related to the increase in metabolism due to the increase of thyroid hormones. Chronic cold exposure also increased the conversion of T4 to T3, which is more potent in thermogenic effect. © Georg Thieme Verlag KG Stuttgart · New York.

Genetic erosion in wild populations makes resistance to a pathogen more costly.

PubMed

Luquet, Emilien; Garner, Trenton W J; Léna, Jean-Paul; Bruel, Christophe; Joly, Pierre; Lengagne, Thierry; Grolet, Odile; Plénet, Sandrine

2012-06-01

Populations that have suffered from genetic erosion are expected to exhibit reduced average trait values or decreased variation in adaptive traits when experiencing periodic or emergent stressors such as infectious disease. Genetic erosion may consequentially modify the ability of a potential host population to cope with infectious disease emergence. We experimentally investigate this relationship between genetic variability and host response to exposure to an infectious agent both in terms of susceptibility to infection and indirect parasite-mediated responses that also impact fitness. We hypothesized that the deleterious consequences of exposure to the pathogen (Batrachochytrium dendrobatidis) would be more severe for tadpoles descended from European treefrog (Hyla arborea) populations lacking genetic variability. Although all exposed tadpoles lacked detectable infection, we detected this relationship for some indirect host responses, predominantly in genetically depleted animals, as well as an interaction between genetic variability and pathogen dose on life span during the postmetamorphic period. Lack of infection and a decreased mass and postmetamorphic life span in low genetic diversity tadpoles lead us to conclude that genetic erosion, while not affecting the ability to mount effective resistance strategies, also erodes the capacity to invest in resistance, increased tadpole growth rate, and metamorphosis relatively simultaneously. © 2012 The Author(s). Evolution © 2012 The Society for the Study of Evolution.

Pulmonary function and symptoms in workers exposed to wood dust.

PubMed Central

Shamssain, M H

1992-01-01

BACKGROUND: Exposure to wood dust can cause a variety of lung problems, including chronic airflow obstruction. METHODS: Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), forced expiratory ratio (FEV1/FVC x 100), forced expiratory flow (FEF), forced mid expiratory flow (FMF), peak expiratory flow (PEF), and respiratory symptoms (cough, phlegm, breathlessness, wheezing, and nasal symptoms) were recorded in 145 non-smoking workers (77 male, 68 female) exposed to wood dust in a furniture factory in Umtata, Republic of Transkei, and 152 non-smoking control subjects (77 male, 75 female) from a bottling factory with a clean environment. RESULTS: After adjustment for age and standing height the forced expiratory indices were significantly lower in the exposed male workers than in the control subjects. FEF and PEF in the exposed men were 81.3% and 89.4% of predicted values and were lower than other indices. FVC in exposed men showed a significant inverse correlation with exposure (expressed in number of years of employment). The FVC was reduced by 26 ml per year of employment. The proportion of men with an FEV1/FVC below 70 was higher in exposed workers than in control subjects and higher in the exposed workers with more years of employment. The exposed workers had more respiratory symptoms than the control subjects, the prevalence, especially of cough and nasal symptoms, increasing with the increase in the number of years of employment. CONCLUSION: Workers exposed to pine and fibre dust have more respiratory symptoms and a greater risk of airflow obstruction. PMID:1549828

Occupational exposures and chronic respiratory symptoms. A population-based study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Korn, R.J.; Dockery, D.W.; Speizer, F.E.

1987-08-01

Data from a random sample of 8515 white adults residing in 6 cities in the eastern and midwestern United States were used to examine the relationships between occupational exposures to dust or to gases and fumes and chronic respiratory symptoms; 31% of the population had a history of occupational dust exposure and 30% reported exposure to gas or fumes. After adjusting for smoking habits, age, gender, and city of residence, subjects with either occupational exposure had significantly elevated prevalences of chronic cough, chronic phlegm, persistent wheeze, and breathlessness. The adjusted relative odds of chronic respiratory symptoms for subjects exposed tomore » dust ranged from 1.32 to 1.60. Subjects with gas or fume exposure had relative odds of symptoms between 1.27 and 1.43 when compared with unexposed subjects. Occupational dust exposure was associated with a higher prevalence of chronic obstructive pulmonary disease as defined by an FEV1/FVC ratio of less than 0.6, when comparing exposed and unexposed participants (OR = 1.53, 95% Cl = 1.17-2.08). Gas or fume exposure was associated with a small, but not significant, increase in COPD prevalence. Significant trends were noted for wheeze and phlegm with increasing duration of dust exposure. Although 36% of exposed subjects reported exposure to both dust and fumes, there was no evidence of a multiplicative interaction between the effects of the individual exposures. Smoking was a significant independent predictor of symptoms, but did not appear to modify the effect of dust or fumes on symptom reporting. These data, obtained in random samples of general populations, demonstrate that chronic respiratory symptoms and disease can be independently associated with occupational exposures.« less

Taurine Ameliorates Renal Oxidative Damage and Thyroid Dysfunction in Rats Chronically Exposed to Fluoride.

PubMed

Adedara, Isaac A; Ojuade, Temini Jesu D; Olabiyi, Bolanle F; Idris, Umar F; Onibiyo, Esther M; Ajeigbe, Olufunke F; Farombi, Ebenezer O

2017-02-01

Excessive exposure to fluoride poses several detrimental effects to human health particularly the kidney which is a major organ involved in its elimination from the body. The influence of taurine on fluoride-induced renal toxicity was investigated in a co-exposure paradigm for 45 days using five groups of eight rats each. Group I rats received normal drinking water alone, group II rats were exposed to sodium fluoride (NaF) in drinking water at 15 mg/L alone, group III received taurine alone at a dose of 200 mg/kg group IV rats were co-administered with NaF and taurine (100 mg/kg), while group V rats were co-administered with NaF and taurine (200 mg/kg). Administration of taurine significantly reversed the fluoride-mediated decrease in absolute weight and organo-somatic index of the kidney in the exposed rats. Taurine significantly prevented fluoride-induced elevation in plasma urea and creatinine levels in the exposed rats. Moreover, taurine restored fluoride-mediated decrease in the circulatory concentrations of triiodothyronine, thyroxine, and the ratio of triiodothyronine to thyroxine. Taurine ameliorated fluoride-mediated decrease in renal antioxidant status by significantly enhancing the antioxidant enzyme activities as well as glutathione level in the exposed rats. Additionally, taurine inhibited fluoride-induced renal oxidative damage by markedly decreasing the hydrogen peroxide and malondialdehyde levels as well as improved the kidney architecture in the treated rats. Collectively, taurine protected against fluoride-induced renal toxicity via enhancement of thyroid gland function, renal antioxidant status, and histology in rats.

Effects of 1,8-cineole on hypertension induced by chronic exposure to nicotine in rats.

PubMed

Moon, Hea Kyung; Kang, Purum; Lee, Hui Su; Min, Sun Seek; Seol, Geun Hee

2014-05-01

The monoterpenic oxide 1,8-cineole is a major component of many essential oils. We investigated its effects on systolic blood pressure (SBP) and oxidative stress in rats chronically exposed to nicotine. Male Sprague-Dawley rats (100-120 g) were intraperitoneally injected with 0.8 mg/kg/day nicotine for 21 days, followed by 3 mg/kg nicotine the next day. Rats were subsequently injected intraperitoneally with 0.01, 0.1 and 1 mg/kg 1,8-cineole, or 10 mg/kg nifedipine. SBP was measured using a tail cuff transducer, plasma nitrite concentration was measured colorimetrically, and plasma corticosterone concentration was measured by enzyme immunoassay. We found that 0.1 mg/kg 1,8-cineole significantly reduced SBP, and that 1.0 mg/kg 1,8-cineole significantly increased plasma nitrite concentrations, compared with rats chronically exposed to nicotine alone. Rats chronically exposed to nicotine showed a significant increase in lipid peroxidation levels, an elevation significantly antagonized by treatment with 0.01 mg/kg and 0.1 mg/kg 1,8-cineole. Chronic exposure to nicotine also significantly increased plasma corticosterone levels, but this effect was not diminished by treatment with 1,8-cineole. These results indicate that 1,8-cineole may lower blood pressure, and that this antihypertensive effect may be associated with the regulation of nitric oxide and oxidative stress in rats chronically exposed to nicotine. © 2013 Royal Pharmaceutical Society.

Vocalizations, tadpole, and natural history of Crossodactylus werneri Pimenta, Cruz Caramaschi, 2014 (Anura: Hylodidae), with comments on distribution and intraspecific variation.

PubMed

Vidigal, Izadora; De Carvalho, Thiago R; Clemente-Carvalho, Rute B G; Giaretta, Ariovaldo A

2018-02-28

Crossodactylus werneri was described based on specimens collected in the 1970's at Parque Nacional do Itatiaia, being also reported for nearby localities. We collected specimens that we assigned to C. werneri, and recorded calls of the species during fieldworks at Serra das Cabras (Campinas, state of São Paulo). In this paper, we describe for the first time the vocalizations, tadpole, coloration in life, and comment on aspects of the natural history of C. werneri. Besides, the examination of specimens in zoological collections allowed us to extend the geographic range for this species. We also make remarks on morphological/chromatic variation and provide 16S rDNA sequences for the species. Adults were found along a slow-flowing streamlet with sandy/muddy bottom within a small fragment of secondary forest. Males called between sunset and first hours of the night. Advertisement call consisted of series of pulsed notes. Call duration lasted around 3 s, emitted at the highest rate of 17 calls per minute and six notes per second. Note duration lasted around 18 ms. Notes had poorly defined pulses (irregular and/or weak amplitude modulations along the note). The dominant frequency was about 3380 Hz. Territorial call had a long, well-defined pulsed portion followed by a higher-amplitude "squeak". The dominant frequency was around 3400 Hz. Tadpoles were essentially similar to those of other Crossodactylus species, except by not having nostril ornamentation. Our record of C. werneri in Serra das Cabras might be regarded a rediscovery of this species since C. werneri had not been recorded for more than 30 years until our first record of C. werneri in the field from 2011 and subsequent years. Our record is approximately 100 km west, and Mococa 200 km northwest, from Santo Antônio do Pinhal, the westernmost previous record for C. werneri up to date. Gene sequences (16S rRNA) give insights into the genetic divergence between C. werneri and some congeners.

Global transcriptome profiling reveals molecular mechanisms of metal tolerance in a chronically exposed wild population of brown trout.

PubMed

Uren Webster, T M; Bury, N; van Aerle, R; Santos, E M

2013-08-06

Worldwide, a number of viable populations of fish are found in environments heavily contaminated with metals, including brown trout (Salmo trutta) inhabiting the River Hayle in South-West of England. This population is chronically exposed to a water-borne mixture of metals, including copper and zinc, at concentrations lethal to naïve fish. We aimed to investigate the molecular mechanisms employed by the River Hayle brown trout to tolerate high metal concentrations. To achieve this, we combined tissue metal analysis with whole-transcriptome profiling using RNA-seq on an Illumina platform. Metal concentrations in the Hayle trout, compared to fish from a relatively unimpacted river, were significantly increased in the gills, liver and kidney (63-, 34- and 19-fold respectively), but not the gut. This confirms that these fish can tolerate considerable metal accumulation, highlighting the importance of these tissues in metal uptake (gill), storage and detoxification (liver, kidney). We sequenced, assembled and annotated the brown trout transcriptome using a de novo approach. Subsequent gene expression analysis identified 998 differentially expressed transcripts and functional analysis revealed that metal- and ion-homeostasis pathways are likely to be the most important mechanisms contributing to the metal tolerance exhibited by this population.

Global Transcriptome Profiling Reveals Molecular Mechanisms of Metal Tolerance in a Chronically Exposed Wild Population of Brown Trout

PubMed Central

2013-01-01

Worldwide, a number of viable populations of fish are found in environments heavily contaminated with metals, including brown trout (Salmo trutta) inhabiting the River Hayle in South-West of England. This population is chronically exposed to a water-borne mixture of metals, including copper and zinc, at concentrations lethal to naïve fish. We aimed to investigate the molecular mechanisms employed by the River Hayle brown trout to tolerate high metal concentrations. To achieve this, we combined tissue metal analysis with whole-transcriptome profiling using RNA-seq on an Illumina platform. Metal concentrations in the Hayle trout, compared to fish from a relatively unimpacted river, were significantly increased in the gills, liver and kidney (63-, 34- and 19-fold respectively), but not the gut. This confirms that these fish can tolerate considerable metal accumulation, highlighting the importance of these tissues in metal uptake (gill), storage and detoxification (liver, kidney). We sequenced, assembled and annotated the brown trout transcriptome using a de novo approach. Subsequent gene expression analysis identified 998 differentially expressed transcripts and functional analysis revealed that metal- and ion-homeostasis pathways are likely to be the most important mechanisms contributing to the metal tolerance exhibited by this population. PMID:23834071

[Cognitive disorders in patients with chronic mercury intoxication].

PubMed

Katamanova, E V; Shevchenko, O I; Lakhman, O L; Denisova, I A

2014-01-01

To assess severity of cognitive disorders in chronic mercury intoxication, the authors performed claster and discrimination analysis of neuropsychologic and neurophysiologic research data from workers exposed to mercury during long length of service, from patients with early and marked stages of chronic mercurial intoxication. Cognitive disorders in chronic mercurial intoxication have three severity degrees, in the light degree disorders patients demonstrate lower amplitude of cognitive evoked potentials, poor long-term memory and associative thinking. Moderate cognitive disorders are characterized by decreased visual, long-term memory, concentration of attention, poor optic and spatial gnosis. Marked cognitive disorders with chronic mercurial intoxication present with more decreased long-term, short-term, picturesque memory, poor intellect, optic and spatial gnosis and associative thinking.

Chronic Intermittent Hypoxia and Acetaminophen Induce Synergistic Liver Injury

PubMed Central

Savransky, Vladimir; Reinke, Christian; Jun, Jonathan; Bevans-Fonti, Shannon; Nanayakkara, Ashika; Li, Jianguo; Myers, Allen C.; Torbenson, Michael S.; Polotsky, Vsevolod Y.

2010-01-01

Obstructive sleep apnea (OSA) leads to chronic intermittent hypoxia (CIH) during sleep. OSA has been associated with liver injury. Acetaminophen (APAP) is one of the most commonly used drugs, which has known hepatotoxicity. The goal of the present study was to examine whether CIH increases liver injury, hepatic oxidative stress and inflammation induced by chronic APAP treatment. C57BL/6J mice were exposed to CIH or intermittent air (IA) for 4 weeks. Mice in both groups were treated with intraperitoneal injections of either APAP (200 mg/kg) or normal saline daily. A combination of CIH and APAP caused liver injury with marked increases in serum alanine aminotransferase, aspartate aminotransferase (AST), gamma glutamyl transferase and total bilirubin levels, whereas CIH alone induced only elevation in serum AST levels. APAP alone did not affect serum levels of liver enzymes. Histopathology revealed hepatic necrosis and increased apoptosis in mice exposed to CIH and APAP, whereas the liver remained intact in all other groups. Mice exposed to CIH and APAP exhibited decreased hepatic glutathione in conjunction with a five-fold increase in nitrotyrosine levels, suggesting formation of toxic peroxynitrite in hepatocytes. APAP or CIH alone had no effect on either glutathione or nitrotyrosine. A combination of CIH and APAP caused marked increases in pro-inflammatory chemokines, monocyte chemoattractant protein-1 and macrophage inflammatory protein-2, which were not observed in mice exposed to CIH or APAP alone. We conclude that CIH and chronic APAP treatment lead to synergistic liver injury, which may have clinical implications for patients with OSA. PMID:19028810

Chronic Inhalation Toxicity of Hydrazine: Oncogenic Effects

DTIC Science & Technology

1981-06-01

AFAMRL-TR-81-56 CHRONIC INHALATION TOXICITY OF HYDRAZINE: ONCOGENIC EFFECTS J. D. MacEWEN E. H. VERNOT C C HAUN L . R. KINKEAD UNIVERSITY OF...Acknowledgement is made to A. K. Roychowdhury, Ph.D., J. D. Diaz, G. L . Fogle, Maj. R. Amster and J. A. Sizemore for their significant contributions and...Hemoglobin (g %) for Dogs Exposed to Hydrazine for One Year 49 24 Group Mean Values ± Standard Deviations of Sodium (mEq/ L ) for Dogs Exposed to

Protective factors and predictors of vulnerability to chronic stress: a comparative study of 4 communities after 7 years of continuous rocket fire.

PubMed

Gelkopf, Marc; Berger, Rony; Bleich, Avraham; Silver, Roxane Cohen

2012-03-01

Many communities across the world are chronically exposed to extreme violence. Responses of residents from a city and rural community in Southern Israel, both exposed to 7 years of daily mortar fire, were compared to residents from demographically, socio-economically and geographically comparable non-exposed control samples to examine protective factors and predictors of vulnerability to chronic war-related attacks. Samples from a highly exposed city (Sderot) and a highly exposed rural community region (Otef Aza), along with a demographically comparable comparison non-exposed city (Ofakim) and non-exposed rural community region (Hevel Lachish), were obtained in 2007 using Random Digit Dialing. In total, 740 individuals (81.8% participation rate) were interviewed about trauma exposure, mental health, functioning and health care utilization. In the highly exposed city of Sderot, 97.8% of residents had been in close proximity to falling rockets; in the highly exposed rural community region of Otef Aza, 95.5% were similarly exposed. Despite exposure to chronic rocket attacks, residents of Otef Aza evidenced little symptomatology: only one person (1.5%) reported symptoms consistent with probable posttraumatic stress disorder (PTSD) and functioning levels did not differ from those of non-exposed communities. In contrast, posttraumatic stress (PTS), distress, functional impairment and health care utilization were substantially higher in the highly exposed city of Sderot than the other three communities. Lack of resources was associated with increased vulnerability among city residents; predictors of PTS across all samples included being female, older, directly exposed to rockets, history of trauma, suffering economic loss, and lacking social support. Increased community solidarity, sense of belonging and confidence in authorities may have served a protective function for residents of rural communities, despite the chronic attacks to which they were exposed. Copyright �

Acute and chronic effects of the insecticide endrin on renal function and renal hemodynamics.

DOT National Transportation Integrated Search

1963-10-01

Chronic and acute effects of the insecticide endrin on renal function were studied in dogs. Animals were exposed to endrin chronically by intramuscular injection and acutely by intravenous infusion. In acute studies dogs developed systemic hypertensi...

Inducible Tolerance to Agrochemicals Was Paved by Evolutionary Responses to Predators.

PubMed

Jones, Devin K; Hintz, William D; Schuler, Matthew S; Yates, Erika K; Mattes, Brian M; Relyea, Rick A

2017-12-05

Recent research has reported increased tolerance to agrochemicals in target and nontarget organisms following acute physiological changes induced through phenotypic plasticity. Moreover, the most inducible populations are those from more pristine locations, far from agrochemical use. We asked why do populations with no known history of pesticide exposure have the ability to induce adaptive responses to novel agrochemicals? We hypothesized that increased pesticide tolerance results from a generalized stressor response in organisms, and would be induced following sublethal exposure to natural and anthropogenic stressors. We exposed larval wood frogs (Lithobates sylvaticus) to one of seven natural or anthropogenic stressors (predator cue (Anax spp.), 0.5 or 1.0 mg carbaryl/L, road salt (200 or 1000 mg Cl - /L), ethanol-vehicle control, or no-stressor control) and subsequently tested their tolerance to a lethal carbaryl concentration using time-to-death assays. We observed induced carbaryl tolerance in tadpoles exposed to 0.5 mg/L carbaryl and also in tadpoles exposed to predator cues. Our results suggest that the ability to induce pesticide tolerance likely arose through evolved antipredator responses. Given that antipredator responses are widespread among species, many animals might possess inducible pesticide tolerance, buffering them from agrochemical exposure.

Effects of chronic perfluorooctanoic acid (PFOA) at low concentration on morphometrics, gene expression, and fecundity in zebrafish (Danio rerio).

PubMed

Jantzen, Carrie E; Toor, Fatima; Annunziato, Kate A; Cooper, Keith R

2017-04-01

Perfluorooctanoic acid (PFOA) is a persistent, toxic, anthropogenic chemical recalcitrant to biodegradation. Based on previous studies in lower and higher vertebrates, it was hypothesized that chronic, sub-lethal, embryonic exposure to PFOA in zebrafish (Danio rerio) would adversely impact fish development, survival, and fecundity. Zebrafish embryo/sac-fry were water exposed to 2.0 or 0nM PFOA from 3 to 120hpf, and juvenile to adult cohorts were fed spiked food (8 pM) until 6 months. After chronic exposure, PFOA exposed fish were significantly smaller in total weight and length. Gene expression analysis found a significant decrease of transporters slco2b1, slco4a1, slco3a1 and tgfb1a, and a significant increase of slco1d1 expression. PFOA exposed fish produced significantly fewer eggs with reduced viability and developmental stage delay in F 1 . Chronic, low-dose exposure of zebrafish to PFOA significantly altered normal development, survival and fecundity and would likely impact wild fish population fitness in watersheds chronically exposed to PFOA. Copyright © 2017 Elsevier Inc. All rights reserved.

Giardia-specific cellular immune responses in post-giardiasis chronic fatigue syndrome.

PubMed

Hanevik, Kurt; Kristoffersen, Einar; Mørch, Kristine; Rye, Kristin Paulsen; Sørnes, Steinar; Svärd, Staffan; Bruserud, Øystein; Langeland, Nina

2017-01-28

The role of pathogen specific cellular immune responses against the eliciting pathogen in development of post-infectious chronic fatigue syndrome (PI-CFS) is not known and such studies are difficult to perform. The aim of this study was to evaluate specific anti-Giardia cellular immunity in cases that developed CFS after Giardia infection compared to cases that recovered well. Patients reporting chronic fatigue in a questionnaire study three years after a Giardia outbreak were clinically evaluated five years after the outbreak and grouped according to Fukuda criteria for CFS and idiopathic chronic fatigue. Giardia specific immune responses were evaluated in 39 of these patients by proliferation assay, T cell activation and cytokine release analysis. 20 Giardia exposed non-fatigued individuals and 10 healthy unexposed individuals were recruited as controls. Patients were clinically classified into CFS (n = 15), idiopathic chronic fatigue (n = 5), fatigue from other causes (n = 9) and recovered from fatigue (n = 10). There were statistically significant antigen specific differences between these Giardia exposed groups and unexposed controls. However, we did not find differences between the Giardia exposed fatigue classification groups with regard to CD4 T cell activation, proliferation or cytokine levels in 6 days cultured PBMCs. Interestingly, sCD40L was increased in patients with PI-CFS and other persons with fatigue after Giardia infection compared to the non-fatigued group, and correlated well with fatigue levels at the time of sampling. Our data show antigen specific cellular immune responses in the groups previously exposed to Giardia and increased sCD40L in fatigued patients.

Influence of dissolved oxygen conditions on toxicity of ammonium nitrate to larval natterjack toads.

PubMed

Ortiz-Santaliestra, Manuel E; Marco, Adolfo

2015-07-01

Temporary ponds, where many amphibians from temperate regions breed, show an annual cycle with a maximum water volume in spring followed by a progressive desiccation throughout late spring and summer. This desiccation leads to a decrease in dissolved oxygen and an increase in nitrogen levels, which can additionally increase because of anthropogenic sources such as chemical fertilizers. We analyzed the toxicity posed by environmentally relevant levels of a common nitrogenous fertilizer, ammonium nitrate, at different conditions of oxygen availability to Bufo calamita tadpoles, which typically develop in ephemeral ponds. Ammonium nitrate (90.3 mg N-NO3NH4/l) and hypoxic conditions (initial dissolved oxygen 4.53 ± 0.40 mg/l) caused significant lethal effects after 7 and 12 days of exposure, respectively. At the end of experiment (16 days), mortality rates were 32.5 % in individuals exposed to the fertilizer and 15 % in those growing under hypoxic conditions. When both stressors were combined, they showed an additive effect on tadpole survival. Malformations, such as oedemas and spinal curvatures, and locomotory abnormalities, were detected after 12 days of experiment in >90 % of individuals exposed to 45.2 mg N-NO3NH4/l under hypoxic conditions, whereas none of these stressors by separate related to abnormality rates >35 %. Delayed development was also observed in tadpoles exposed to ammonium nitrate with hypoxia affecting developmental rate only after 12 days of exposure. The results are discussed in terms of potential mechanisms linking negative effects of both factors as well as in terms of potential alterations of the ecological plasticity that often allows amphibians to survive in unpredictable environments.

Neuropsychological Functioning in Gulf War Veterans Exposed to Pesticides and Pyridostigmine Bromide

DTIC Science & Technology

2008-02-01

processing speed and mood and sequelae from overt poisoning from organophosphate pesticides can result in lasting deficits in the domains of visuomotor...R. G., O’Malley, M., Chrislip, D., & Russo, J. (1994). Chronic neurological sequelae to organophosphate pesticide poisoning . American...War Veterans Exposed to Pesticides and Pyridostigmine Bromide PRINCIPAL INVESTIGATOR: Maxine Krengel, Ph.D

EXPOSE-R on Mission on the ISS

NASA Astrophysics Data System (ADS)

Panitz, Corinna; Rabbow, Elke; Rettberg, Petra; Barczyk, Simon; Kloss, Maria; Reitz, Guenther

Currently EXPOSE-R is on mission! This astrobiological exposure facility was accommodated at the universal workplace URM-D Zenith payload site, located outside the Russian Svezda Module of the International Space Station (ISS) by extravehicular activity (EVA) on March 10th 2009. It contains 3 trays accommodating 12 sample compartments with sample carriers in three levels either open to space vacuum or kept in a defined gas environment. In its 8 experiments of biological and chemical content, more than 1200 individual samples are exposed to solar ultraviolet (UV) radiations, vacuum, cosmic rays or extreme temperature variations. In their different experiments the involved scientists are studying the question of life's origin on Earth and the results of their experiments are contributing to different aspects of the evolution and distribution of life in the Universe. Additionally integrated into the EXPOSE-R facility are several dosimeters monitoring the ionising and the solar UV-radiation during the mission to deliver useful information to complement the sample analysis. In close cooperation with the DLR and the Technical University Munich (TUM), the Rheinisch -Westfülische Technischen Hochschule Aachen (RWTH Aachen) operates the experiment "Spores". a This is one of the 6 astrobiological experiments of the ROSE-Consortium" (Response of Or-ganisms to Space Environment) of the EXPOSE-R mission. In these experiments spores of bacteria, fungi and ferns are being over layered or mixed with meteorite material. The analysis of the effect of the space parameters on different biological endpoints of the spores of the mi-croorganism Bacillus subtilis will be performed after the retrieval of the experiment scheduled for the end of 2010. Parallel to the space mission an identical set of samples was accommodated into EXPOSE-R trays identical in construction to perform the Mission Ground Reference (MGR) Test. Currently this MGR Test is carried out in the Planetary and Space

Prevalence of Irritable Bowel Syndrome and Chronic Fatigue 10 Years After Giardia Infection.

PubMed

Litleskare, Sverre; Rortveit, Guri; Eide, Geir Egil; Hanevik, Kurt; Langeland, Nina; Wensaas, Knut-Arne

2018-03-06

Irritable bowel syndrome (IBS) is a complication that can follow gastrointestinal infection, but it is not clear if patients also develop chronic fatigue. We investigated the prevalence and odds ratio of IBS and chronic fatigue 10 years after an outbreak of Giardia lamblia, compared with a control cohort, and changes in prevalence over time. We performed a prospective follow-up study of 1252 laboratory-confirmed cases of giardiasis (exposed), which developed in Bergen, Norway in 2004. Statistics Norway provided us with information from 2504 unexposed individuals from Bergen, matched by age and sex (controls). Questionnaires were mailed to participants 3, 6, and 10 years after the outbreak. Results from the 3- and 6-year follow-up analyses have been published previously. We report the 10-year data and changes in prevalence among time points, determined by logistic regression using generalized estimating equations. The prevalence of IBS 10 years after the outbreak was 43% (n = 248) among 576 exposed individuals and 14% (n = 94) among 685 controls (adjusted odds ratio for development of IBS in exposed individuals, 4.74; 95% CI, 3.61-6.23). At this time point, the prevalence of chronic fatigue was 26% (n = 153) among 587 exposed individuals and 11% (n = 73) among 692 controls (adjusted odds ratio, 3.01; 95% CI, 2.22-4.08). The prevalence of IBS among exposed persons did not change significantly from 6 years after infection (40%) to 10 years after infection (43%; adjusted odds ratio for the change 1.03; 95% CI, 0.87-1.22). However, the prevalence of chronic fatigue decreased from 31% at 6 years after infection to 26% at 10 years after infection (adjusted odds ratio for the change 0.74; 95% CI, 0.61-0.90). The prevalence of IBS did not change significantly from 6 years after an outbreak of Giardia lamblia infection in Norway to 10 years after. However, the prevalence of chronic fatigue decreased significantly from 6 to 10 years afterward. IBS and chronic fatigue were

Proteomic analysis of kidney in rats chronically exposed to monosodium glutamate.

PubMed

Sharma, Amod; Wongkham, Chaisiri; Prasongwattana, Vitoon; Boonnate, Piyanard; Thanan, Raynoo; Reungjui, Sirirat; Cha'on, Ubon

2014-01-01

Chronic monosodium glutamate (MSG) intake causes kidney dysfunction and renal oxidative stress in the animal model. To gain insight into the renal changes induced by MSG, proteomic analysis of the kidneys was performed. Six week old male Wistar rats were given drinking water with or without MSG (2 mg/g body weight, n = 10 per group) for 9 months. Kidneys were removed, frozen, and stored at -75°C. After protein extraction, 2-D gel electrophoresis was performed and renal proteome profiles were examined with Colloidal Coomassie Brilliant Blue staining. Statistically significant protein spots (ANOVA, p<0.05) with 1.2-fold difference were excised and analyzed by LC-MS. Proteomic data were confirmed by immunohistochemistry and Western blot analyses. The differential image analysis showed 157 changed spots, of which 71 spots were higher and 86 spots were lower in the MSG-treated group compared with those in the control group. Eight statistically significant and differentially expressed proteins were identified: glutathione S-transferase class-pi, heat shock cognate 71 kDa, phosphoserine phosphatase, phosphoglycerate kinase, cytosolic glycerol-3-phosphate dehydrogenase, 2-amino-3-carboxymuconate-6-semialdehyde decarboxylase, α-ketoglutarate dehydrogenase and succinyl-CoA ligase. The identified proteins are mainly related to oxidative stress and metabolism. They provide a valuable clue to explore the mechanism of renal handling and toxicity on chronic MSG intake.

Effects of copper on growth, metamorphosis and endocrine disruption of Bufo gargarizans larvae.

PubMed

Wang, Chao; Liang, Gang; Chai, Lihong; Wang, Hongyuan

2016-01-01

Chinese toad (Bufo gargarizans) tadpoles were exposed to copper (1, 6.4, 32 and 64μgL(-1) copper) from the beginning of larval period through completion of metamorphosis. We examined the effects of chronic copper exposure on mortality, growth, time to metamorphosis, tail resorption time, body size at the metamorphic climax (Gs 42) and completion of metamorphosis (Gs 46) and thyroid gland histology. In addition, type 2 and 3 iodothyronine deiodinase (Dio2 and Dio3), thyroid hormone receptors (TRα and TRβ) mRNA levels were also measured to assess disruption of TH synthesis. Our result showed that 6.4-64μgL(-1) copper concentration increased the mortality and inhibited the growth of B. gargarizans tadpoles. In addition, significant reduction in size at Gs 42 and a time delay to Gs 42 were observed at 6.4-64μgL(-1) copper treatments. Moreover, histological examinations have clearly revealed that 64μgL(-1) copper caused follicular cell hyperplasia in thyroid gland. According to real-time PCR results, exposure to 32 and 64μgL(-1) copper significantly up-regulated mRNA expression of Dio3, but down-regulated mRNA expression of TRα and TRβ mRNA level. We concluded that copper delayed amphibian metamorphosis through changing mRNA expression of Dio3, TRα and TRβ, which suggests that copper might have the endocrine-disrupting effect. Copyright © 2015 Elsevier B.V. All rights reserved.

Additive effects of mean temperature, temperature variability, and chlorothalonil to red-eyed treefrog (Agalychnis callidryas) larvae.

PubMed

Alza, Carissa M; Donnelly, Maureen A; Whitfield, Steven M

2016-12-01

Amphibian populations are declining globally, and multiple anthropogenic stressors, including contamination by pesticides and shifting climates, are driving these declines. Climate change may increase average temperatures or increase temperature variability, either of which may affect the susceptibility of nontarget organisms to contaminants. Eight-day ecotoxicological assays were conducted with red-eyed treefrog (Agalychnis callidryas) larvae to test for additive and interactive effects of exposure to the fungicide chlorothalonil, average temperature, and temperature variability on tadpole growth and survival. Egg masses were collected from seasonal ponds at La Selva Biological Station in Costa Rica, and tadpoles were exposed to a series of chlorothalonil concentrations across a range of ecologically relevant mean temperatures (23.4-27.3 °C) and daily temperature fluctuations (1.1-9.9 °C). Survival was measured each day, and tadpole growth was measured at the end of each trial. Concentrations of chlorothalonil ≥60 µg/L reduced survival, although survival was not affected by mean temperature or daily temperature range, and there were no synergistic interactions between chlorothalonil and temperature regime on survival. Chlorothalonil suppressed tadpole growth at relatively low concentrations (∼15 µg/L). There were impacts of both average temperature and daily temperature range on tadpole growth, although there were no synergistic interactions between temperature regimes and chlorothalonil. The results should inform efforts to manage ecosystems impacted by multiple large-scale anthropogenic stressors as well as methods for the design of ecologically appropriate toxicology trials. Environ Toxicol Chem 2016;35:2998-3004. © 2016 SETAC. © 2016 SETAC.

Airway disease in highway and tunnel construction workers exposed to silica.

PubMed

Oliver, L Christine; Miracle-McMahill, Heidi

2006-12-01

Construction workers employed in a unique type of tunnel construction known as tunnel jacking were exposed over an 18-month period to respirable crystalline silica at concentrations that exceeded the OSHA permissible exposure limit. The present study examines workplace exposures and occurrence of airway disease in these workers. Medical and occupational histories and chest radiographs were obtained on 343 active construction workers who had worked on the site during the period in question. Chest radiographs were interpreted according to the ILO-1980 system of classification. Standardized questions were used to develop an algorithm to define symptoms consistent with asthma (SCA) and to determine these respiratory outcomes: chronic bronchitis, shortness of breath (SOB), and physician-diagnosed asthma (current vs. not current). Relationships with each of three work activities were examined: slurry wall breakthrough (SWB), chipping caisson overpour, and tunneling/mining. Participants included laborers, carpenters, tunnel workers, ironworkers, operating engineers, and electricians. No cases of silicosis were found on chest X-ray. Overall prevalence of chronic bronchitis, SCA, SOB, and physician-diagnosed asthma was 10.7%, 25%, 29%, and 6.6%, respectively. Odds ratios (OR) for carpenters compared to laborers were significantly elevated for chronic bronchitis, SCA, and SOB. SWB was associated with chronic bronchitis and SCA (OR 4.93, 95% CI = 1.01, 24.17; OR 3.32, 95% CI = 1.25, 8.84, respectively). The interaction between SWB, SCA, and trade was significant for carpenters (OR 6.87, 95% CI = 1.66, 28.39). Inverse trends were observed for months on the site and chronic bronchitis, SCA, and SOB (P = 0.0374, 0.0006, and 0.0307, respectively). Tunnel construction workers exposed to respirable crystalline silica and cement dust are at increased risk for airway disease. Extent of risk varies by trade and work activity. Our data indicate the importance of bystander exposures and

Risk factors for respiratory work disability in a cohort of pulp mill workers exposed to irritant gases

PubMed Central

2011-01-01

Background The association between chronic respiratory diseases and work disability has been demonstrated a number of times over the past 20 years, but still little is known about work disability in occupational cohorts of workers exposed to respiratory irritants. This study investigated job or task changes due to respiratory problems as an indicator of work disability in pulp mill workers occupationally exposed to irritants. Methods Data about respiratory symptoms and disease diagnoses, socio-demographic variables, occupational exposures, gassing episodes, and reported work changes due to respiratory problems were collected using a questionnaire answered by 3226 pulp mill workers. Information about work history and departments was obtained from personnel files. Incidence and hazard ratios for respiratory work disability were calculated with 95% confidence intervals (CI). Results The incidence of respiratory work disability among these pulp mill workers was 1.6/1000 person-years. The hazard ratios for respiratory work disability were increased for workers reporting gassings (HR 5.3, 95% CI 2.7-10.5) and for those reporting physician-diagnosed asthma, chronic bronchitis, and chronic rhinitis, when analyzed in the same model. Conclusions This cohort study of pulp mill workers found that irritant peak exposure during gassing episodes was a strong predictor of changing work due to respiratory problems, even after adjustment for asthma, chronic bronchitis, and chronic rhinitis. PMID:21896193

[Chronic noise exposure and the cardiovascular system in aircraft pilots].

PubMed

Tomei, F; Papaleo, B; Baccolo, T P; Tomao, E; Alfi, P; Fantini, S

1996-01-01

The aim of this study was to assess whether pilots are exposed to any risk of effects on the cardiovascular apparatus, whether chronic exposure to noise can be a risk factor for this occupation, the importance of intensity, length and type of exposure to noise, and if any relationship exists between audiometric deficits and cardiovascular effects. The study comprised 416 pilots subdivided into two groups according to the different levels of chronic exposure to noise, and a group of 150 control subjects not exposed to noise. The results showed: a) a higher prevalence of hypertension, nearly always diastolic, and of ECG abnormalities in the group of pilots of turboprop aircraft compared to jet plane pilots and to controls (p < 0.005 and p < 0.01 respectively); b) a higher prevalence of orthostatic hypotension in the two groups of pilots than in the controls (p < 0.05); c) a higher prevalence of hypertension with audiometric deficit compared to hypertension without audiometric deficit both in the more heavily and in the less heavily exposed to noise (p < 0.05), and a higher prevalence of hypertension with audiometric deficit in subjects exposed to higher levels of noise compared to hypertension with deficit but in subjects with lower levels of exposure (p < 0.05); d) a higher prevalence of abnormalities of basal, maximum effort and recovery ECG in pilots exposed to higher noise intensity (p < 0.05); e) improved hypertensive response to ergometric test in pilots with basal hypertension; f) subjects with a maximal load up to 120 W belonged prevalently to the group exposed to more intense noise (p < 0.001), while those with maximal load up to 210 W (p < 0.001) belonged to the group exposed to less intense noise. Considering that pilots are comparable for traditional cardiovascular risk factors, including age, both within the group and with the controls, the results confirm 1) that pilots could be exposed to the risk of effects on the cardiovascular apparatus, 2) that

DNA damage in children exposed to secondhand cigarette smoke and its association with oxidative stress.

PubMed

Shermatov, Kabil; Zeyrek, Dost; Yildirim, Faruk; Kilic, Mehmet; Cebi, Nazime; Kocyigit, Abdurrahim

2012-12-01

To compare oxidative status, total antioxidant capacity and values of DNA damage in peripheral blood lymphocytes in children exposed to secondhand cigarette smoke with healthy controls. Analytical, Observational. 54 children without any chronic diseases, attending the healthy child monitoring polyclinic. These comprised 27 children who had been exposed to passive cigarette smoke and 27 children who had not been exposed to cigarette smoke. Urine cotinine levels by the chemiluminescent technique; DNA damage by alkaline comet assay; and total oxidant status (TOS) using a novel automated measurement method. The mean urine cotinine, TOS, Oxidative Stress Index (OSI) and DNA damage values of the group exposed to cigarette smoke were determined to be at significantly higher level compared to the group not exposed to cigarette smoke (P<0.001). No statistically significant difference was determined in the TAS level between the two groups (P=0.1) The results showed that TOS levels, OSI index and DNA damage in peripheral blood lymphocytes were significantly higher in children exposed to secondhand cigarette smoke than in those not exposed to secondhand cigarette smoke.

The influence of chronic and subacute exposure to lead on the levels of prolactin, leptin, osteopontin, and follistatin in humans.

PubMed

Dobrakowski, M; Kasperczyk, A; Czuba, Z P; Machoń-Grecka, A; Szlacheta, Z; Kasperczyk, S

2017-06-01

This study was designed to determine the levels of prolactin, leptin, osteopontin, and follistatin in workers chronically and subacutely exposed to lead compounds. The examined population consisted of three groups. The first group was composed of 56 male workers who were chronically exposed to lead for 13.38 ± 10.38 years. The second group served as a control group and consisted of 24 male administrative workers, while the third group included 32 male workers exposed to lead for 40 ± 3 days. The levels of leptin, osteopontin, and prolactin were significantly lower in the group of workers chronically exposed to lead than in the control group by 42%, 26%, and 41%, respectively. The levels of follistatin did not differ between those groups. The levels of all measured hormones did not change after a short-term exposure to lead compared to baseline. Chronic lead exposure is associated with significantly decreased level of prolactin, leptin, and osteopontin. Lead-induced changes in the levels of these hormones may disturb many functions of the human body, including the immune response, metabolism, reproduction, and bone turnover.

Antidepressant-like Effect of Bacopaside I in Mice Exposed to Chronic Unpredictable Mild Stress by Modulating the Hypothalamic-Pituitary-Adrenal Axis Function and Activating BDNF Signaling Pathway.

PubMed

Zu, Xianpeng; Zhang, Mingjian; Li, Wencai; Xie, Haisheng; Lin, Zhang; Yang, Niao; Liu, Xinru; Zhang, Weidong

2017-11-01

Preliminary studies conducted in our laboratory have confirmed that Bacopaside I (BS-I), a saponin compound isolated from Bacopa monnieri, displayed antidepressant-like activity in the mouse behavioral despair model. The present investigation aimed to verify the antidepressant-like action of BS-I using a mouse model of behavioral deficits induced by chronic unpredictable mild stress (CUMS) and further probe its underlying mechanism of action. Mice were exposed to CUMS for a period of 5 consecutive weeks to induce depression-like behavior. Then, oral gavage administrations with vehicle (model group), fluoxetine (12 mg/kg, positive group) or BS-I (5, 15, 45 mg/kg, treated group) once daily were started during the last two weeks of CUMS procedure. The results showed that BS-I significantly ameliorated CUMS-induced depression-like behaviors in mice, as characterized by an elevated sucrose consumption in the sucrose preference test and reduced immobility time without affecting spontaneous locomotor activity in the forced swimming test, tail suspension test and open field test. It was also found that BS-I treatment reversed the increased level of plasma corticosterone and decreased mRNA and protein expressions of glucocorticoid receptor induced by CUMS exposure, indicating that hypothalamic-pituitary-adrenal (HPA) axis hyperactivity of CUMS-exposed mice was restored by BS-I treatment. Furthermore, chronic administration of BS-I elevated expression levels of brain-derived neurotrophic factor (BDNF) (mRNA and protein) and activated the phosphorylation of extracellular signal-regulated kinase and cAMP response element-binding protein in the hippocampus and prefrontal cortex in mice subjected to CUMS procedure. Taken together, these results indicated that BS-I exhibited an obvious antidepressant-like effect in mouse model of CUMS-induced depression that was mediated, at least in part, by modulating HPA hyperactivity and activating BDNF signaling pathway.

Topology-induced bifurcations for the nonlinear Schrödinger equation on the tadpole graph.

PubMed

Cacciapuoti, Claudio; Finco, Domenico; Noja, Diego

2015-01-01

In this paper we give the complete classification of solitons for a cubic nonlinear Schrödinger equation on the simplest network with a nontrivial topology: the tadpole graph, i.e., a ring with a half line attached to it and free boundary conditions at the junction. This is a step toward the modelization of condensate propagation and confinement in quasi-one-dimensional traps. The model, although simple, exhibits a surprisingly rich behavior and in particular we show that it admits: (i) a denumerable family of continuous branches of embedded solitons vanishing on the half line and bifurcating from linear eigenstates and threshold resonances of the system; (ii) a continuous branch of edge solitons bifurcating from the previous families at the threshold of the continuous spectrum with a pitchfork bifurcation; and (iii) a finite family of continuous branches of solitons without linear analog. All the solutions are explicitly constructed in terms of elliptic Jacobian functions. Moreover we show that families of nonlinear bound states of the above kind continue to exist in the presence of a uniform magnetic field orthogonal to the plane of the ring when a well definite flux quantization condition holds true. In this sense the magnetic field acts as a control parameter. Finally we highlight the role of resonances in the linearization as a signature of the occurrence of bifurcations of solitons from the continuous spectrum.

[Diagnostic neurologic procedures and certification in persons chronically exposed to carbon disulfide in light of personal cases].

PubMed

Sińczuk-Walczak, H

2000-01-01

Carbon disulfide is a poison of particularly neotropic properties. In order to diagnose chronic occupational intoxication with carbon disulfide, a very careful examination of the central and peripheral nervous systems in required. The presence of subjective disorders only does not as yet provide grounds for diagnosing chronic intoxication. Organic changes like chronic encephalopathy or polyneuropathy after excluding the so called 'idiopathic' neurological diseases, may serve as a basis for certifying occupational disease.

Proteomic Analysis of Kidney in Rats Chronically Exposed to Monosodium Glutamate

PubMed Central

Sharma, Amod; Wongkham, Chaisiri; Prasongwattana, Vitoon; Boonnate, Piyanard; Thanan, Raynoo; Reungjui, Sirirat; Cha’on, Ubon

2014-01-01

Background Chronic monosodium glutamate (MSG) intake causes kidney dysfunction and renal oxidative stress in the animal model. To gain insight into the renal changes induced by MSG, proteomic analysis of the kidneys was performed. Methods Six week old male Wistar rats were given drinking water with or without MSG (2 mg/g body weight, n = 10 per group) for 9 months. Kidneys were removed, frozen, and stored at –75°C. After protein extraction, 2-D gel electrophoresis was performed and renal proteome profiles were examined with Colloidal Coomassie Brilliant Blue staining. Statistically significant protein spots (ANOVA, p<0.05) with 1.2-fold difference were excised and analyzed by LC-MS. Proteomic data were confirmed by immunohistochemistry and Western blot analyses. Results The differential image analysis showed 157 changed spots, of which 71 spots were higher and 86 spots were lower in the MSG-treated group compared with those in the control group. Eight statistically significant and differentially expressed proteins were identified: glutathione S-transferase class-pi, heat shock cognate 71 kDa, phosphoserine phosphatase, phosphoglycerate kinase, cytosolic glycerol-3-phosphate dehydrogenase, 2-amino-3-carboxymuconate-6-semialdehyde decarboxylase, α-ketoglutarate dehydrogenase and succinyl-CoA ligase. Conclusion The identified proteins are mainly related to oxidative stress and metabolism. They provide a valuable clue to explore the mechanism of renal handling and toxicity on chronic MSG intake. PMID:25551610

Re-evaluation of the interrelationships among the behavioral tests in rats exposed to chronic unpredictable mild stress

PubMed Central

Hu, Congli; Luo, Ying; Wang, Hong; Kuang, Shengnan; Liang, Guojuan; Yang, Yang; Mai, Shaoshan; Yang, Junqing

2017-01-01

The chronic unpredictable mild stress model of depression has been widely used as an experimental tool to investigate human psychopathology. Our objective was to provide an update on the validity and reliability of the chronic unpredictable mild stress model, by analyzing the interrelationships among the indexes using stepwise discriminant analysis and Pearson correlation coefficient to examine the possible combinations. We evaluated the depressive rats in both the presence and the absence of chronic unpredictable mild stress, using weight change, percentage of sucrose preference, coat state, splash test, open-field test, elevated plus-maze test, forced swimming test, and Morris water maze test. The results showed that 6-week-long chronic unpredictable mild stress produces significant depression and anxiety-like behavior. The combination of body weight change, percentage of sucrose preference, coat state score, open-field score, grooming latency of splash test, immobility time in force swimming test, and platform crossing in the Morris water maze test can effectively discriminate between normal and chronic unpredictable mild stress rats. Strong interrelationships were noted among these indexes in both open-field test and elevated plus-maze test. In conclusion, there might be certain criteria for the combination of behavioral endpoints, which is advantageous to more effectively and reliably assess the chronic unpredictable mild stress induced depression model. PMID:28931086

Alterations in antioxidant defense system of workers chronically exposed to arsenic, cadmium and mercury from coal flying ash.

PubMed

Zeneli, Lulzim; Sekovanić, Ankica; Ajvazi, Majlinda; Kurti, Leonard; Daci, Nexhat

2016-02-01

Humans are exposed to different stress factors that are responsible for over-production of reactive oxygen species. Exposure to heavy metals is one of these factors. The aim of the study was to analyze the effect of chronic exposure to heavy metals through coal flying ash on the efficiency of antioxidative defensive mechanisms, represented by the activity of superoxide dismutase, glutathione peroxidase and ascorbic acid. Nonessential elements such as arsenic and mercury levels showed a significant increase (p > 0.001) in the power plant workers rather than in the control subjects. There were no significant differences of blood cadmium between power plant workers and control subjects. We found a significant positive correlation (p < 0.05) between BAs/SZn (r = 0.211), BAs/BSe (r = 0.287), BCd/SCu (r = 0.32) and BHg/BSe (r = 0.263) in the plant workers. Red blood cell antioxidant enzymes and plasma ascorbic acid were significantly lower in power plants workers than in the control group (p < 0.002). We can conclude that levels of mercury, arsenic and cadmium in blood, despite their concentration within the reference values, significantly affect plasma ascorbic acid concentration, superoxide dismutase and glutathione peroxidase activity, which are able to increase the risk of oxidative stress.

Systemic inflammation, endothelial dysfunction, and activation in clinically healthy children exposed to air pollutants.

PubMed

Calderón-Garcidueñas, L; Villarreal-Calderon, R; Valencia-Salazar, G; Henríquez-Roldán, C; Gutiérrez-Castrellón, P; Torres-Jardón, R; Osnaya-Brizuela, N; Romero, L; Torres-Jardón, R; Solt, A; Reed, W

2008-03-01

Mexico City children are chronically exposed to significant concentrations of air pollutants and exhibit chronic respiratory-tract inflammation. Epidemiological, controlled human exposures, laboratory-based animal models, and in vitro/in vivo studies have shown that inflammatory, endothelial dysfunction, and endothelial damage mediators are upregulated upon exposure to particulate matter (PM). Endothelial dysfunction is a critical event in cardiovascular disease. The focus of this work was to investigate whether exposure to ambient air pollution including PM(2.5) produces systemic inflammation and endothelial injury in healthy children. We measured markers of endothelial activation, and inflammatory mediators in 52 children age 8.6+/-0.1 yr, residents of Mexico City (n: 28) or of Polotitlán (n: 24), a city with low levels of pollutants. Mexico City children had significant increases in inflammatory mediators and vasoconstrictors, including tumor necrosis factor (TNF)alpha, prostaglandin (PG) E2, C-reactive protein, interleukin-1beta, and endothelin-1. There was a significant anti-inflammatory response, and a downregulation of vascular adhesion molecule-1, intercellular adhesion molecule-1 and -2, and selectins sE and sL. Results from linear regression found TNF a positively associated with 24- and 48-h cumulative levels of PM(2.5), while the 7-d PM(2.5) value was negatively associated with the numbers of white blood cells in peripheral blood in highly exposed children. Systemic subclinical inflammation, increased endothelin- 1, and significant downregulation of soluble adhesion molecules are seen in Mexico City children. Children chronically exposed to fine PM above the standard could be at risk of developing cardiovascular diseases, atherosclerosis, stroke, and other systemic effects later in life.

Proteomic analysis of liver in rats chronically exposed to fluoride.

PubMed

Pereira, Heloísa Aparecida Barbosa da Silva; Leite, Aline de Lima; Charone, Senda; Lobo, Janete Gualiume Vaz Madureira; Cestari, Tania Mary; Peres-Buzalaf, Camila; Buzalaf, Marília Afonso Rabelo

2013-01-01

Fluoride (F) is a potent anti-cariogenic element, but when ingestion is excessive, systemic toxicity may be observed. This can occur as acute or chronic responses, depending on both the amount of F and the time of exposure. The present study identified the profile of protein expression possibly associated with F-induced chronic hepatotoxicity. Weanling male Wistar rats (three-weeks old) were divided into three groups and treated with drinking water containing 0, 5 or 50 mg/L F for 60 days (n=6/group). At this time point, serum and livers were collected for F analysis, which was done using the ion-sensitive electrode, after hexamethyldisiloxane-facilitated diffusion. Livers were also submitted to histological and proteomic analyses (2D-PAGE followed by LC-MS/MS). Western blotting was done for confirmation of the proteomic data A dose-response was observed in serum F levels. In the livers, F levels were significantly increased in the 50 mg/L F group compared to groups treated with 0 and 5 mg/L F. Liver morphometric analysis did not reveal alterations in the cellular structures and lipid droplets were present in all groups. Proteomic quantitative intensity analysis detected 33, 44, and 29 spots differentially expressed in the comparisons between control vs. 5 mg/L F, control vs. 50 mg/L F, and 5 mg/L vs. 50 mg/L F, respectively. From these, 92 proteins were successfully identified. In addition, 18, 1, and 5 protein spots were shown to be exclusive in control, 5, and 50 mg/L F, respectively. Most of proteins were related to metabolic process and pronounced alterations were seen for the high-F level group. In F-treated rats, changes in the apolipoprotein E (ApoE) and GRP-78 expression may account for the F-induced toxicity in the liver. This can contribute to understanding the molecular mechanisms underlying hepatoxicity induced by F, by indicating key-proteins that should be better addressed in future studies.

Akebia quinata Decaisne aqueous extract acts as a novel anti-fatigue agent in mice exposed to chronic restraint stress.

PubMed

Park, Sun Haeng; Jang, Seol; Lee, Si Woo; Park, Sun Dong; Sung, Yoon-Young; Kim, Ho Kyoung

2018-08-10

Akebia quinata Decaisne extract (AQE; Lardizabalaceae) is used in traditional herbal medicine for stress- and fatigue-related depression, improvement of fatigue, and mental relaxation. To clarify the effects of AQE on stress-induced fatigue, we investigated the neuroprotective pharmacological effects of A. quinata Decaisne in mice exposed to chronic restraint stress. Seven-week old C57BL/6 mice chronically stressed by immobilization for 3 h daily for 15 d and non-stressed control mice underwent daily oral administration of AQE or distilled water. The open field, sucrose preference, and forced swimming behavioral tests were carried out once weekly, and immunohistochemical analyses of NeuN, brain-derived neurotrophic factor (BDNF), phosphorylated cAMP response element-binding (CREB) protein, and BDNF receptor tropomyosin receptor kinase B (TrkB) in striatum and hippocampus were performed at the end of the experimental period. Brain levels of serotonin, adrenaline, and noradrenaline as well as serum levels of corticosterone were measured. Behavioral tests showed that treatment with AQE improved all lethargic behaviors examined. AQE significantly attenuated the elevated levels of adrenaline, noradrenaline, and serotonin in the brain and corticosterone, alanine transaminase, and aspartate transaminase levels in the serum. Histopathological analysis showed that AQE reduced liver injury and lateral ventricle size in restraint-stress mice via inhibition of neuronal cell death. Immunohistochemical analysis showed increased phosphorylation of CREB and expression of BDNF and its receptor TrkB in striatum and hippocampus. Chlorogenic acid, isochlorogenic acid A, and isochlorogenic acid C were identified as the primary components of AQE. All three agents increased expression of BDNF in SH-SY5Y cells and PC12 cells with H 2 O 2 -induced neuronal cell damage. AQE may have a neuroprotective effect and ameliorate the effects of stress and fatigue-associated brain damage through

Tadpole-like Conformations of Huntingtin Exon 1 Are Characterized by Conformational Heterogeneity that Persists regardless of Polyglutamine Length.

PubMed

Newcombe, Estella A; Ruff, Kiersten M; Sethi, Ashish; Ormsby, Angelique R; Ramdzan, Yasmin M; Fox, Archa; Purcell, Anthony W; Gooley, Paul R; Pappu, Rohit V; Hatters, Danny M

2018-05-11

Soluble huntingtin exon 1 (Httex1) with expanded polyglutamine (polyQ) engenders neurotoxicity in Huntington's disease. To uncover the physical basis of this toxicity, we performed structural studies of soluble Httex1 for wild-type and mutant polyQ lengths. Nuclear magnetic resonance experiments show evidence for conformational rigidity across the polyQ region. In contrast, hydrogen-deuterium exchange shows absence of backbone amide protection, suggesting negligible persistence of hydrogen bonds. The seemingly conflicting results are explained by all-atom simulations, which show that Httex1 adopts tadpole-like structures with a globular head encompassing the N-terminal amphipathic and polyQ regions and the tail encompassing the C-terminal proline-rich region. The surface area of the globular domain increases monotonically with polyQ length. This stimulates sharp increases in gain-of-function interactions in cells for expanded polyQ, and one of these interactions is with the stress-granule protein Fus. Our results highlight plausible connections between Httex1 structure and routes to neurotoxicity. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Metamorphosis of two amphibian species after chronic cadmium exposure in outdoor aquatic mesocosms

USGS Publications Warehouse

James, S.M.; Little, E.E.; Semlitsch, R.D.

2005-01-01

Amphibian larvae at contaminated sites may experience an alteration of metamorphic traits and survival compared to amphibians in uncontaminated conditions. Effects of chronic cadmium (Cd) exposure on the metamorphosis of American toads (Bufo americanus) and southern leopard frogs (Rana sphenocephala) were determined. The two species were reared separately from shortly after hatching through metamorphosis in outdoor mesocosms (1,325-L polyethylene cattle tanks) that simulated natural ponds and enhanced environmental realism relative to the laboratory. Both species exhibited a decrease in survival with increasing initial nominal aqueous Cd concentration. Cadmium treatment did not influence mass at metamorphosis for either species when survival was included as a covariate, but increased the age at metamorphosis for the American toads. The whole body Cd content of metamorphs increased with aqueous Cd treatment level for both species, and the American toads tended to possess more elevated residues. Cadmium quickly partitioned out of the water column and accumulated in and altered the abundance of the tadpoles' diet. Cadmium-contaminated sites may produce fewer metamorphs, and those that survive will metamorphose later and contain Cd. Interspecific differences in the response variables illustrate the importance of testing multiple species when assessing risk.

Asbestos bodies in bronchoalveolar lavage fluid. A study of 20 asbestos-exposed individuals and comparison to patients with other chronic interstitial lung diseases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roggli, V.L.; Piantadosi, C.A.; Bell, D.Y.

1986-09-01

We studied the asbestos body (AB) content of bronchoalveolar lavage fluid from 20 patients with a history of occupational asbestos exposure, 31 patients with sarcoidosis and 5 patients with idiopathic pulmonary fibrosis. The cellular lavage pellet was digested in sodium hypochlorite and filtered onto Nuclepore filters for AB quantification by light microscopy. ABs were found in 15 of 20 asbestos-exposed individuals, 9 of 31 sarcoidosis cases and 2 of 5 patients with idiopathic pulmonary fibrosis. There was a statistically significant difference in the number of ABs per million cells recovered or per milliliter of recovered lavage fluid in the asbestos-exposedmore » group as compared to the other categories of chronic interstitial lung disease. The highest levels occurred in patients with asbestosis. Large numbers of asbestos bodies in the lavage fluid (greater than 1 AB/10(6) cells) were indicative of considerable occupational asbestos exposure, whereas occasional bodies were a nonspecific finding.« less

Characterization and quantification of corticosteroid-binding globulin in a southern toad, Bufo terrestris, exposed to coal-combustion-waste

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ward, C.K.; Fontes, C.; Breuner, C.W.

2007-05-15

Corticosteroid-binding globulin (CBG) is a plasma protein that binds corticosterone and may regulate access of hormone to tissues. The role of CBG during a stress response is not clear. In this study, southern toads, Bufo terrestris, were exposed to a chronic pollutant (coal-combustion-waste), to determine changes in CBG and free corticosterone levels. Since toads exposed to chronic pollutants in previous studies did not exhibit the predicted changes in metabolic rate and mass, but did experience a significant elevation in total corticosterone, we hypothesized that CBG would likewise increase and thus, mitigate the effects of a chronic (i.e. 2 months) pollutantmore » stressor. To conduct this study, we first characterized the properties of CBG in southern toads. After characterization, we monitored the changes in CBG, total corticosterone, and free corticosterone in male toads that were exposed to either coal-combustion-waste or control conditions. CBG increased in all groups throughout the experiment. Total corticosterone, on the other hand, was only significantly elevated at four weeks of exposure to coal-combustion-waste. The increase in CBG did not parallel the increase in total corticosterone; as a result, free corticosterone levels were not buffered by CBG, but showed a peak at four weeks similar to total corticosterone. This finding indicates that, in this species, CBG may not provide a protective mechanism during long-term pollution exposure.« less

Bioavailability and chronic toxicity of bismuth citrate to earthworm Eisenia andrei exposed to natural sandy soil.

PubMed

Omouri, Zohra; Hawari, Jalal; Fournier, Michel; Robidoux, Pierre Yves

2018-01-01

The present study describes bioavailability and chronic effects of bismuth to earthworms Eisenia andrei using OECD reproduction test. Adult earthworms were exposed to natural sandy soil contaminated artificially by bismuth citrate. Average total concentrations of bismuth in soil recovered by HNO 3 digestion ranged from 75 to 289mg/kg. Results indicate that bismuth decreased significantly all reproduction parameters of Eisenia andrei at concentrations ≥ 116mg/kg. However, number of hatched cocoons and number of juveniles seem to be more sensitive than total number of cocoons, as determined by IC 50 ; i.e., 182, 123 and > 289mg/kg, respectively. Bismuth did not affect Eisenia andrei growth and survival, and had little effect on phagocytic efficiency of coelomocytes. The low immunotoxicity effect might be explained by the involvement of other mechanisms i.e. bismuth sequestered by metal-binding compounds. After 28 days of exposure bismuth concentrations in earthworms tissue increased with increasing bismuth concentrations in soil reaching a stationary state of 21.37mg/kg dry tissue for 243mg Bi/kg dry soil total content. Data indicate also that after 56 days of incubation the average fractions of bismuth available extracted by KNO 3 aqueous solution in soil without earthworms varied from 0.0051 to 0.0229mg/kg, while in soil with earthworms bismuth concentration ranged between 0.310-1.347mg/kg dry soil. We presume that mucus and chelating agents produced by earthworms and by soil or/and earthworm gut microorganisms could explain this enhancement, as well as the role of dermal and ingestion routes of earthworms uptake to soil contaminant. Copyright © 2017 Elsevier Inc. All rights reserved.

Effects of Circadian Disruption on Methamphetamine Consumption in Methamphetamine-Exposed Rats

PubMed Central

Doyle, Susan E.; Feng, Hanting; Garber, Garrett; Menaker, Michael; Lynch, Wendy J.

2015-01-01

Rationale A substantial number of clinical studies indicate associations between sleep abnormalities and drug abuse; however, the role played by the circadian system in the development of addiction is largely unknown. Objective The aim of this study was to examine the effects of experimentally induced chronic jet lag on methamphetamine consumption in a rat model of methamphetamine drinking. Methods Male Sprague-Dawley rats (n=32) were housed in running wheel cages in a 12:12 light:dark cycle. One group of rats (n=16) was given two weeks of forced methamphetamine consumption (0.01% in drinking water; meth pre-exposed) while a second group (n=16, not pre-exposed) received water only. This was followed by a two week abstinence period during which half of the animals from each group were exposed to 4 consecutive 6-hr advancing phase shifts of the light:dark cycle, while the other half remained on the original light:dark cycle. Methamphetamine consumption was assessed in all rats following the deprivation period using a two-bottle choice paradigm. Results Methamphetamine consumption was initially lower in methamphetamine pre-exposed vs. not pre-exposed rats. However, during the second week following abstinence, consumption was significantly higher in phase shifted rats of the methamphetamine pre-exposed group compared to all other groups. Conclusions These data reveal an effect of circadian rhythm disturbance on methamphetamine consumption, and suggest that dysregulation of the circadian system be considered in the etiology of relapse and addiction. PMID:25543849

Effects of circadian disruption on methamphetamine consumption in methamphetamine-exposed rats.

PubMed

Doyle, Susan E; Feng, Hanting; Garber, Garrett; Menaker, Michael; Lynch, Wendy J

2015-06-01

A substantial number of clinical studies indicate associations between sleep abnormalities and drug abuse; however, the role played by the circadian system in the development of addiction is largely unknown. The aim of this study was to examine the effects of experimentally induced chronic jet lag on methamphetamine consumption in a rat model of methamphetamine drinking. Male Sprague-Dawley rats (n = 32) were housed in running wheel cages in a 12:12 h light:dark cycle. One group of rats (n = 16) was given 2 weeks of forced methamphetamine consumption (0.01 % in drinking water; meth pre-exposed) while a second group (n = 16, not pre-exposed) received water only. This was followed by a 2-week abstinence period during which half of the animals from each group were exposed to four consecutive 6-h advancing phase shifts of the light:dark cycle, while the other half remained on the original light:dark cycle. Methamphetamine consumption was assessed in all rats following the deprivation period using a two-bottle choice paradigm. Methamphetamine consumption was initially lower in methamphetamine pre-exposed versus not pre-exposed rats. However, during the second week following abstinence, consumption was significantly higher in phase-shifted rats of the methamphetamine pre-exposed group compared to all other groups. These data reveal an effect of circadian rhythm disturbance on methamphetamine consumption and suggest that dysregulation of the circadian system be considered in the etiology of relapse and addiction.

Chronic occupational stress exposure may increase the vulnerability to acoustic trauma in military professionals.

PubMed

Mălina, Ciumaşu-Rimbu

2015-01-01

Today little is known about the connection between chronic stress exposure and hearing loss. These effects cannot be explained by differences in HPA axis response but recent studies saying that chronic stress induced limbic system alterations spread to nonlimbic areas affecting auditory system might be the key. On the other hand we know that subjects exposed to chronic stress may prove hypersensitivity to novel stressors. The aim of this study is to confirm that occupational chronic stress (OCS) exposure determines vulnerability to acoustic trauma and to establish a method to identify individuals at risk prior to their exposure to high intensity acoustic stimulus. 60 military personnel with known acoustic trauma injury evidentiated through audiograms and occupational chronic stress exposure quantified through validated questionnaires were exposed to mild novel stressor: occupational medicine evaluation and clinically assessed for maladaptive cardiovascular response (MCVR). Employees were split in two groups, group 1 (MCVR) and group 2 (non MCVR). We found positive correlation between level of perceived OCS and level of hearing loss on entire group and between groups with values of parameters significantly higher in group 1. Subjects exposed to OCS with hypersensitivity to novel stressor evidentiated through maladaptive cardiovascular stress response may be more vulnerable to high intensity acoustic stimulus and consequently acoustic trauma. Establishing methods and biomarkers that help us indentify individuals at risk of developing acoustic trauma might decrease the high burden of hearing loss.

NEUROCHEMICAL EFFECTS OF CHRONIC DIETARY AND REPEATED HIGH-LEVEL ACUTE EXPOSURE TO CHLORPYRIFOS IN RATS.

EPA Science Inventory

Lots of information is available surrounding the acute toxicity of anticholinesterase pesticides, but these have been very few detailed studies on the chronic effects of these pesticides. Humans are exposed on a chronic basis and some humans believe that have been affected advers...

Chronic Pain: How Challenging Are DDIs in the Analgesic Treatment of Inpatients with Multiple Chronic Conditions?

PubMed

Siebenhuener, Klarissa; Eschmann, Emmanuel; Kienast, Alexander; Schneider, Dominik; Minder, Christoph E; Saller, Reinhard; Zimmerli, Lukas; Blaser, Jürg; Battegay, Edouard; Holzer, Barbara M

2017-01-01

Chronic pain is common in multimorbid patients. However, little is known about the implications of chronic pain and analgesic treatment on multimorbid patients. This study aimed to assess chronic pain therapy with regard to the interaction potential in a sample of inpatients with multiple chronic conditions. We conducted a retrospective study with all multimorbid inpatients aged ≥18 years admitted to the Department of Internal Medicine of University Hospital Zurich in 2011 (n = 1,039 patients). Data were extracted from the electronic health records and reviewed. We identified 433 hospitalizations of patients with chronic pain and analyzed their combinations of chronic conditions (multimorbidity). We then classified all analgesic prescriptions according to the World Health Organization (WHO) analgesic ladder. Furthermore, we used a Swiss drug-drug interactions knowledge base to identify potential interactions between opioids and other drug classes, in particular coanalgesics and other concomitant drugs. Chronic pain was present in 38% of patients with multimorbidity. On average, patients with chronic pain were aged 65.7 years and had a mean number of 6.6 diagnoses. Hypertension was the most common chronic condition. Chronic back pain was the most common painful condition. Almost 90% of patients were exposed to polypharmacotherapy. Of the chronic pain patients, 71.1% received opioids for moderate to severe pain, 43.4% received coanalgesics. We identified 3,186 potential drug-drug interactions, with 17% classified between analgesics (without coanalgesics). Analgesic drugs-related DDIs, in particular opioids, in multimorbid patients are often complex and difficult to assess by using DDI knowledge bases alone. Drug-multimorbidity interactions are not sufficiently investigated and understood. Today, the scientific literature is scarce for chronic pain in combination with multiple coexisting medical conditions and medication regimens. Our work may provide useful

The CNS connectome of a tadpole larva of Ciona intestinalis (L.) highlights sidedness in the brain of a chordate sibling.

PubMed

Ryan, Kerrianne; Lu, Zhiyuan; Meinertzhagen, Ian A

2016-12-06

Left-right asymmetries in brains are usually minor or cryptic. We report brain asymmetries in the tiny, dorsal tubular nervous system of the ascidian tadpole larva, Ciona intestinalis . Chordate in body plan and development, the larva provides an outstanding example of brain asymmetry. Although early neural development is well studied, detailed cellular organization of the swimming larva's CNS remains unreported. Using serial-section EM we document the synaptic connectome of the larva's 177 CNS neurons. These formed 6618 synapses including 1772 neuromuscular junctions, augmented by 1206 gap junctions. Neurons are unipolar with at most a single dendrite, and few synapses. Some synapses are unpolarised, others form reciprocal or serial motifs; 922 were polyadic. Axo-axonal synapses predominate. Most neurons have ciliary organelles, and many features lack structural specialization. Despite equal cell numbers on both sides, neuron identities and pathways differ left/right. Brain vesicle asymmetries include a right ocellus and left coronet cells.

[Comparative evaluation of the functional state of the respiratory system in workers exposed to asbestos and cotton dust].

PubMed

Izycki, J; Gielec, L

1979-01-01

63 spinners exposed to cotton dust and 75 spinners exposed to asbestos dust were examined. In the women working in asbestos spinning room chronic nonspecific respiratory tract diseases prevalence was found to amount to 30% and in the cotton exposed group it was 15%. Mean values of lungs' vital capacity remained within the due values, although they were statistically significantly lower in asbestos exposed spinners (p less than 0,001). On the other hand, the percentage ratio of the forced expiratory capacity of 1 second was statistically significantly lower (0,001 less than p less than 0,01) in those exposed to cotton dust. The authors point to the occurrence of functional disturbances of the respiratory tract prior to radiological symptoms of lung asbestosis and their correlation with clinical symptoms.

Depression-like behavior and stressor-induced neuroendocrine activation in female prairie voles exposed to chronic social isolation

PubMed Central

Grippo, Angela J.; Cushing, Bruce S.; Carter, C. Sue

2010-01-01

Objective Previous evidence suggests that responses to social stressors may play a mechanistic role in the behavioral and physiological changes associated with affective disorders such as depression. Prairie voles (Microtus ochrogaster) are socially monogamous rodents that share features of social behavior with humans, and therefore might provide a useful model for examining social regulation of behaviors and physiological responses related to depression. In the present study we hypothesized that social isolation in female prairie voles would induce depression-relevant behaviors and altered neuroendocrine responses to an acute social stressor. Methods Twenty adult female prairie voles were exposed to either 60 days of social isolation or paired (control) housing, and tested for a depression-like behavior (anhedonia), numbers of corticotropin-releasing factor- and oxytocin-immunoreactive cells in the paraventricular nucleus of the hypothalamus, and circulating levels of hormones and peptide in response to an acute social stressor (resident-intruder test). Results Chronic social isolation produced anhedonia, measured by a reduction in sucrose intake and sucrose preference relative to paired animals. Compared to paired animals, isolated prairie voles displayed increased plasma hormone and peptide levels (oxytocin, arginine vasopressin, and corticosterone) following a 5-minute resident-intruder test, mirrored by an increased number of oxytocin- and corticotropin-releasing factor-immunoreactive cells in the hypothalamic paraventricular nucleus. Conclusions These findings suggest that isolation in a socially monogamous rodent model induces both behavioral and neuroendocrine changes that are relevant to depression, and may provide insight into the mechanisms that underlie the development and/or maintenance of depressive disorders in humans. PMID:17289829

Cancer in patients with rheumatic diseases exposed to TNF antagonists.

PubMed

Carmona, Loreto; Abasolo, Lydia; Descalzo, Miguel A; Pérez-Zafrilla, Beatriz; Sellas, Agustí; de Abajo, Francisco; Gomez-Reino, Juan J

2011-08-01

To describe the risk of cancer in patients exposed to tumor necrosis factor (TNF) antagonists. The following 2 clinical cohorts were studied: (1) BIOBADASER 2.0: a registry of patients suffering from rheumatic diseases exposed to TNF antagonists (2531 rheumatoid arthritis (RA), 1488 spondyloarthropathies, and 675 other rheumatic conditions); and (2) EMECAR: a cohort of 789 RA patients not exposed to TNF antagonists. Cancer incidence rates (IR) per 1000 patient-years and incidence rate ratios (IRR) were calculated for BIOBADASER 2.0 and EMECAR patients. The IR over time in BIOBADASER 2.0 patients was analyzed by joinpoint regression. The IRR was estimated to compare cancer rates in exposed versus nonexposed RA patients. Standardized incidence and mortality ratios (SIR, SMR) were also estimated. Risk factors for cancer in patients exposed to TNF antagonists were investigated by generalized linear models. The SMR for cancer in BIODASER 2.0 was 0.67 (95% CI: 0.51-0.86), and the SIR was 0.1 (95% CI 0.03-0.23). The IR in RA patients exposed to TNF antagonists was 5.8 (95% CI: 4.4-7.6), and the adjusted IRR was 0.48 (95% CI: 0.09-2.45). The IR in patients with previous cancer was 26.4 (95% CI: 4.1-171.5). Age, chronic obstructive pulmonary disease, and steroids were associated with a higher risk of developing cancer. The IR decreased after the first 4 months of exposure, without statistical significance. Overall cancer and mortality rates in patients with rheumatic diseases exposed to TNF antagonists are no higher than in the background Spanish population. However special attention should be paid to elderly patients, those with previous cancers, and patients treated with steroids. Copyright © 2011 Elsevier Inc. All rights reserved.

Hormonal regulation of growth and life span of bullfrog tadpole tail epidermal cells cultured in vitro.

PubMed

Nishikawa, A; Yoshizato, K

1986-02-01

Epidermal cells were dissociated from tails of the bullfrog tadpole, Rana catesbeiana, and cultured to investigate their response to steroid and thyroid hormones. Charcoal-treated serum (CTS) was used in the growth medium when cells were to be grown in the absence of steroid and thyroid hormones. The cells could be maintained for 2 weeks with a small increase in cell number in medium that contained CTS (CTS medium). Addition of cortisol to CTS medium increased both cellular attachment to the culture dishes and the proliferation of the attached cells with an optimum concentration of 5 X 10(-7) M. The cells remained viable and attached for at least a week. Cortisol stimulated the rate of protein synthesis 1.8-fold but did not alter the rate of DNA synthesis. The cells did not proliferate in the medium containing triiodothyronine (T3) and detached themselves from the dish within 5 days, which occurred in a dose-dependent manner with a maximum effect at 10(-8) M. It drastically decreased the rate of DNA synthesis but did not influence the rate of protein synthesis. These responses of cells to cortisol and T3 may reflect growth and death of tail epidermal cells in vivo at metamorphosis.

Regulation of body mass in rats exposed to chronic acceleration

NASA Technical Reports Server (NTRS)

Pitts, G. C.; Bull, L. S.; Oyama, J.

1975-01-01

Female rats approximately 6 mo old were chronically centrifuged for up to 30 days at 2.76 G or 3.18 G and sacrificed at intervals for body-composition study. Both fat and the fat-free body mass (FFBM) were reduced during the 1st wk of centrifugation, with the fat showing considerably more variation both within and between groups. The FFBM was reduced below control level to the same extent in rats fed commercial chow, a high-fat diet, or a high-protein diet or in rats prefasted to produce a body-mass deficit at the start of centrifugation. There were no centrifugation-associated changes in body water content. It was concluded that body fat showed no evidence of regulation, FFBM is regulated at any constant level of acceleration between 1 and 4.15 G, and the change in FFBM induced by a change in acceleration is probably not regulated.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lajmanovich, Rafael C., E-mail: lajmanovich@hotmail.com; Faculty of Biochemistry and Biological Sciences; Junges, Celina M.

The effects of commercial formulations of Bacillus thuringiensisvar.israelensis (Bti) on non-target organisms are still a matter of debate; in amphibians, the risks of Bti are little known. To evaluate the toxicity of a commercial liquid (aqueous suspension, AS) formulation of Bti (Introban{sup ®}) on Leptodactylus latrans tadpoles, including median lethal concentration (LC{sub 50}) and no-and lowest–observed-effect concentrations (NOEC and LOEC, respectively), as well as the possible effects of Bti on oxidative responses, erythrocytes genotoxicity, and histology of the intestines. In the laboratory, tadpoles were exposed to nominal concentrations of 0 (control), 2.5, 5, 10, 20 and 40 mg/L of formulatedmore » Bti-AS. Glutathione S-transferase (GST) and catalase (CAT) activities, as well as formation of erythrocyte nuclear abnormalities (ENAs), and histological effect were measured in tadpoles displaying survival rates >85%. L. latrans tadpoles were sensitive to exposure to Bti-AS, reaching 100% mortality after 48 h of exposure at the highest concentration. Bti-AS induced GST and CAT enzymes and genotoxicity (erythrocyte's nuclear abnormalities), and caused intestine's histopathology. Our results demonstrate that toxicity of Bti-AS is dose-dependent for L. latrans tadpoles and that sublethal exposure alters enzymes of oxidative stress, induces genotoxicity, and causes intestine damage. Further research is needed to evaluate the ecotoxicological risk of the massive use of Bti formulations on amphibian populations that commonly used suburban wastewater or urban waterbodies to reproduce and where this biopesticide is frequently applied. - Highlights: • An ecotoxicological evaluation of a Bti formulation on amphibian was conducted. • Toxicity of Bti-AS was dose-dependent for Leptodactylus latrans tadpoles. • Sublethal exposure altered the enzymes of oxidative stress (GST and CAT). • Bti-AS was genotoxic because increased MN frequencies (CO: 0.82–2.74�

Chronic respiratory disease among the elderly in South Africa: any association with proximity to mine dumps?

PubMed

Nkosi, Vusumuzi; Wichmann, Janine; Voyi, Kuku

2015-04-03

There is increasing evidence that environmental factors such as air pollution from mine dumps, increase the risk of chronic respiratory symptoms and diseases. The aim of this study was to investigate the association between proximity to mine dumps and prevalence of chronic respiratory disease in people aged 55 years and older. Elderly persons in communities 1-2 km (exposed) and 5 km (unexposed), from five pre-selected mine dumps in Gauteng and North West Province, in South Africa were included in a cross-sectional study. Structured interviews were conducted with 2397 elderly people, using a previously validated ATS-DLD-78 questionnaire from the British Medical Research Council. Exposed elderly persons had a significantly higher prevalence of chronic respiratory symptoms and diseases than those who were unexposed., Results from the multiple logistic regression analysis indicated that living close to mine dumps was significantly associated with asthma (OR = 1.57; 95% CI: 1.20 - 2.05), chronic bronchitis (OR = 1.74; 95 CI: 1.25 - 2.39), chronic cough (OR = 2.02; 95% CI: 1.58 - 2.57), emphysema (OR = 1.75; 95% CI: 1.11 - 2.77), pneumonia (OR = 1.38; 95% CI: 1.07 - 1.77) and wheeze (OR = 2.01; 95% CI: 1.73 - 2.54). Residing in exposed communities, current smoking, ex-smoking, use of paraffin as main residential cooking/heating fuel and low level of education emerged as independent significant risk factors for chronic respiratory symptoms and diseases. This study suggests that there is a high level of chronic respiratory symptoms and diseases among elderly people in communities located near to mine dumps in South Africa.

Synthesis of amphiphilic tadpole-shaped linear-cyclic diblock copolymers via ring-opening polymerization directly initiating from cyclic precursors and their application as drug nanocarriers.

PubMed

Wan, Xuejuan; Liu, Tao; Liu, Shiyong

2011-04-11

We report on the facile synthesis of well-defined amphiphilic and thermoresponsive tadpole-shaped linear-cyclic diblock copolymers via ring-opening polymerization (ROP) directly initiating from cyclic precursors, their self-assembling behavior in aqueous solution, and the application of micellar assemblies as controlled release drug nanocarriers. Starting from a trifunctional core molecule containing alkynyl, hydroxyl, and bromine moieties, alkynyl-(OH)-Br, macrocyclic poly(N-isopropylacrylamide) (c-PNIPAM) bearing a single hydroxyl functionality was prepared by atom transfer radical polymerization (ATRP), the subsequent end group transformation into azide functionality, and finally the intramacromolecular ring closure reaction via click chemistry. The target amphiphilic tadpole-shaped linear-cyclic diblock copolymer, (c-PNIPAM)-b-PCL, was then synthesized via the ROP of ε-caprolactone (CL) by directly initiating from the cyclic precursor. In aqueous solution at 20 °C, (c-PNIPAM)-b-PCL self-assembles into spherical micelles consisting of hydrophobic PCL cores and well-solvated coronas of cyclic PNIPAM segments. For comparison, linear diblock copolymer with comparable molecular weight and composition, (l-PNIPAM)-b-PCL, was also synthesized. It was found that the thermoresponsive coronas of micelles self-assembled from (c-PNIPAM)-b-PCL exhibit thermoinduced collapse and aggregation at a lower critical thermal phase transition temperature (T(c)) compared with those of (l-PNIPAM)-b-PCL. Temperature-dependent drug release profiles from the two types of micelles of (c-PNIPAM)-b-PCL and (l-PNIPAM)-b-PCL loaded with doxorubicin (Dox) were measured, and the underlying mechanism for the observed difference in releasing properties was proposed. Moreover, MTT assays revealed that micelles of (c-PNIPAM)-b-PCL are almost noncytotoxic up to a concentration of 1.0 g/L, whereas at the same polymer concentration, micelles loaded with Dox lead to ∼60% cell death. Overall, chain

An integrated omic analysis of hepatic alteration in medaka fish chronically exposed to cyanotoxins with possible mechanisms of reproductive toxicity.

PubMed

Qiao, Qin; Le Manach, Séverine; Huet, Hélène; Duvernois-Berthet, Evelyne; Chaouch, Soraya; Duval, Charlotte; Sotton, Benoit; Ponger, Loïc; Marie, Arul; Mathéron, Lucrèce; Lennon, Sarah; Bolbach, Gérard; Djediat, Chakib; Bernard, Cécile; Edery, Marc; Marie, Benjamin

2016-12-01

Cyanobacterial blooms threaten human health as well as the population of other living organisms in the aquatic environment, particularly due to the production of natural toxic components, the cyanotoxin. So far, the most studied cyanotoxins are microcystins (MCs). In this study, the hepatic alterations at histological, proteome and transcriptome levels were evaluated in female and male medaka fish chronically exposed to 1 and 5 μg L -1 microcystin-LR (MC-LR) and to the extract of MC-producing Microcystis aeruginosa PCC 7820 (5 μg L -1 of equivalent MC-LR) by balneation for 28 days, aiming at enhancing our understanding of the potential reproductive toxicity of cyanotoxins in aquatic vertebrate models. Indeed, both MC and Microcystis extract adversely affect reproductive parameters including fecundity and egg hatchability. The liver of toxin treated female fish present glycogen storage loss and cellular damages. The quantitative proteomics analysis revealed that the quantities of 225 hepatic proteins are dysregulated. In particular, a notable decrease in protein quantities of vitellogenin and choriogenin was observed, which could explain the decrease in reproductive output. Liver transcriptome analysis through Illumina RNA-seq reveals that over 100-400 genes are differentially expressed under 5 μg L -1  MC-LR and Microcystis extract treatments, respectively. Ingenuity pathway analysis of the omic data attests that various metabolic pathways, such as energy production, protein biosynthesis and lipid metabolism, are disturbed by both MC-LR and the Microcystis extract, which could provoke the observed reproductive impairment. The transcriptomics analysis also constitutes the first report of the impairment of circadian rhythm-related gene induced by MCs. This study contributes to a better understanding of the potential consequences of chronic exposure of fish to environmental concentrations of cyanotoxins, suggesting that Microcystis extract could impact a

Adolescent environmental enrichment prevents behavioral and physiological sequelae of adolescent chronic stress in female (but not male) rats.

PubMed

Smith, Brittany L; Morano, Rachel L; Ulrich-Lai, Yvonne M; Myers, Brent; Solomon, Matia B; Herman, James P

2017-11-22

The late adolescent period is characterized by marked neurodevelopmental and endocrine fluctuations in the transition to early adulthood. Adolescents are highly responsive to the external environment, which enhances their ability to adapt and recover from challenges when given nurturing influences, but also makes them vulnerable to aberrant development when exposed to prolonged adverse situations. Female rats are particularly sensitive to the effects of chronic stress in adolescence, which manifests as passive coping strategies and blunted hypothalamo-pituitary adrenocortical (HPA) stress responses in adulthood. We sought to intervene by exposing adolescent rats to environmental enrichment (EE) immediately prior to and during chronic stress, hypothesizing that EE would minimize or prevent the long-term effects of stress that emerge in adult females. To test this, we exposed male and female rats to EE on postnatal days (PND) 33-60 and implemented chronic variable stress (CVS) on PND 40-60. CVS consisted of twice-daily unpredictable stressors. Experimental groups included: CVS/unenriched, unstressed/EE, CVS/EE and unstressed/unenriched (n = 10 of each sex/group). In adulthood, we measured behavior in the open field test and forced swim test (FST) and collected blood samples following the FST. We found that environmental enrichment given during the adolescent period prevented the chronic stress-induced transition to passive coping in the FST and reversed decreases in peak adrenocortical responsiveness observed in adult females. Adolescent enrichment had little to no effect on males or unstressed females tested in adulthood, indicating that beneficial effects are specific to females that were exposed to chronic stress.

Proteome-wide changes in primary skin keratinocytes exposed to diesel particulate extract-A role for antioxidants in skin health.

PubMed

Rajagopalan, Pavithra; Jain, Ankit P; Nanjappa, Vishalakshi; Patel, Krishna; Mangalaparthi, Kiran K; Babu, Niraj; Cavusoglu, Nükhet; Roy, Nita; Soeur, Jeremie; Breton, Lionel; Pandey, Akhilesh; Gowda, Harsha; Chatterjee, Aditi; Misra, Namita

2018-05-21

Skin acts as a protective barrier against direct contact with pollutants but inhalation and systemic exposure have indirect effect on keratinocytes. Exposure to diesel exhaust has been linked to increased oxidative stress. To investigate global proteomic alterations in diesel particulate extract (DPE)/its vapor exposed skin keratinocytes. We employed Tandem Mass Tag (TMT)-based proteomics to study effect of DPE/DPE vapor on primary skin keratinocytes. We observed an increased expression of oxidative stress response protein NRF2, upon chronic exposure of primary keratinocytes to DPE/its vapor which includes volatile components such as polycyclic aromatic hydrocarbons (PAHs). Mass spectrometry-based quantitative proteomics led to identification 4490 proteins of which 201 and 374 proteins were significantly dysregulated (≥1.5 fold, p ≤ 0.05) in each condition, respectively. Proteins involved in cellular processes such as cornification (cornifin A), wound healing (antileukoproteinase) and differentiation (suprabasin) were significantly downregulated in primary keratinocytes exposed to DPE/DPE vapor. These results were corroborated in 3D skin models chronically exposed to DPE/DPE vapor. Bioinformatics analyses indicate that DPE and its vapor affect distinct molecular processes in skin keratinocytes. Components of mitochondrial oxidative phosphorylation machinery were seen to be exclusively overexpressed upon chronic DPE vapor exposure. In addition, treatment with an antioxidant like vitamin E partially restores expression of proteins altered upon exposure to DPE/DPE vapor. Our study highlights distinct adverse effects of chronic exposure to DPE/DPE vapor on skin keratinocytes and the potential role of vitamin E in alleviating adverse effects of environmental pollution. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Prevalence of Chronic Diseases in Adults Exposed to Arsenic-Contaminated Drinking Water

PubMed Central

Zierold, Kristina M.; Knobeloch, Lynda; Anderson, Henry

2004-01-01

Inorganic arsenic is naturally occurring in groundwaters throughout the United States. This study investigated arsenic exposure and self-report of 9 chronic diseases. We received private well-water samples and questionnaires from 1185 people who reported drinking their water for 20 or more years. Respondents with arsenic levels of 2 μg/L or greater were statistically more likely to report a history of depression, high blood pressure, circulatory problems, and bypass surgery than were respondents with arsenic concentrations less than 2 μg/L. PMID:15514231

Effects of chronic lead exposure on pregnant sheep and their progeny

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, R.M.; Buck, W.B.

1976-01-01

Twelve sheep were exposed to sublethal doses of powdered metallic lead in their feed during the entire period of gestation and nine were treated as unexposed controls. The rate of lambing was 18% and 100% in the exposed and unexposed sheep, respectively. Abortions occurred at a rate of 27% in the exposed group but did not occur in the control group. Levels of lead in blood and urine of exposed sheep were related to the amount of lead in the feed. On the basis of this study it may be concluded that chronic lead poisoning in sheep causes abortion, miscarriages,more » and transitory sterility. 23 references, 3 figures, 3 tables.« less

Effects of Chronic Central Arginine Vasopressin (AVP) on Maternal Behavior in Chronically Stressed Rat Dams

PubMed Central

Coverdill, Alexander J.; McCarthy, Megan; Bridges, Robert S.; Nephew, Benjamin C.

2012-01-01

Exposure of mothers to chronic stressors during pregnancy or the postpartum period often leads to the development of depression, anxiety, or other related mood disorders. The adverse effects of mood disorders are often mediated through maternal behavior and recent work has identified arginine vasopressin (AVP) as a key neuropeptide hormone in the expression of maternal behavior in both rats and humans. Using an established rodent model that elicits behavioral and physiological responses similar to human mood disorders, this study tested the effectiveness of chronic AVP infusion as a novel treatment for the adverse effects of exposure to chronic social stress during lactation in rats. During early (day 3) and mid (day 10) lactation, AVP treatment significantly decreased the latency to initiate nursing and time spent retrieving pups, and increased pup grooming and total maternal care (sum of pup grooming and nursing). AVP treatment was also effective in decreasing maternal aggression and the average duration of aggressive bouts on day 3 of lactation. Central AVP may be an effective target for the development of treatments for enhancing maternal behavior in individuals exposed to chronic social stress. PMID:24349762

New CYP1 genes in the frog Xenopus (Silurana) tropicalis: Induction patterns and effects of AHR agonists during development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Joensson, Maria E., E-mail: maria.jonsson@ebc.uu.se; Biology Department, Redfield 3-42 MS 32, Woods Hole Oceanographic Institution, Woods Hole, MA, 02543; Berg, Cecilia

2011-01-15

The Xenopus tropicalis genome shows a single gene in each of the four cytochrome P450 1 (CYP1) subfamilies that occur in vertebrates, designated as CYP1A, CYP1B1, CYP1C1, and CYP1D1. We cloned the cDNAs of these genes and examined their expression in untreated tadpoles and in tadpoles exposed to waterborne aryl hydrocarbon receptor agonists, 3,3',4,4',5-pentachlorobiphenyl (PCB126), {beta}-naphthoflavone ({beta}NF), or indigo. We also examined the effects of PCB126 on expression of genes involved in stress response, cell proliferation, thyroid homeostasis, and prostaglandin synthesis. PCB126 induced CYP1A, CYP1B1, and CYP1C1 but had little effect on CYP1D1 (77-, 1.7-, 4.6- and 1.4-fold induction versusmore » the control, respectively). {beta}NF induced CYP1A and CYP1C1 (26- and 2.5-fold), while, under conditions used, indigo tended to induce only CYP1A (1.9-fold). The extent of CYP1 induction by PCB126 and {beta}NF was positively correlated to the number of putative dioxin response elements 0-20 kb upstream of the start codons. No morphological effect was observed in tadpoles exposed to 1 nM-10 {mu}M PCB126 at two days post-fertilization (dpf) and screened 20 days later. However, in 14-dpf tadpoles a slight up-regulation of the genes for PCNA, transthyretin, HSC70, Cu-Zn SOD, and Cox-2 was observed two days after exposure to 1 {mu}M PCB126. This study of the full suite of CYP1 genes in an amphibian species reveals gene- and AHR agonist-specific differences in response, as well as a much lower sensitivity to CYP1 induction and short-term toxicity by PCB126 compared with in fish larvae. The single genes in each CYP1 subfamily may make X. tropicalis a useful model for mechanistic studies of CYP1 functions.« less

[The combined use of capillaroscopy and skin thermometry in health surveillance of workers exposed to hand-arm vibration].

PubMed

Riolfi, A; Perbellini, L

2010-01-01

The use of nailfold capillaroscopy combined with skin thermometry in the study of microcirculation of the hands in workers exposed to hand-arm vibration is assessed. Fifty-eight subjects were studied; 40 asymptomatic forestry workers exposed to hand-arm vibration, 13 forestry workers exposed to hand-arm vibration with Raynaud-like symptoms confirmed by skin thermometry; 5 controls. Reduction of capillary density was observed in workers exposed to vibrating tools with respect to controls. Tortuosity of capillary loops was significantly more frequent in subjects exposed to vibrating tools than in controls. No statistically significant difference in capillary vessels of the hands was found between asymptomatic exposed subjects and workers affected by Raynaud-like symptoms. In our sample nailfold capillaroscopy shows good sensibilty and specificity in detecting capillary modifications secondary to exposure to hand-vibration. Weaker evidence is instead given in order to actual disturbances of hands circulation in chronic exposure to vibrating tools.

Chronic intermittent hypoxia and acetaminophen induce synergistic liver injury in mice.

PubMed

Savransky, Vladimir; Reinke, Christian; Jun, Jonathan; Bevans-Fonti, Shannon; Nanayakkara, Ashika; Li, Jianguo; Myers, Allen C; Torbenson, Michael S; Polotsky, Vsevolod Y

2009-02-01

Obstructive sleep apnoea (OSA) leads to chronic intermittent hypoxia (CIH) during sleep. Obstructive sleep apnoea has been associated with liver injury. Acetaminophen (APAP; known as paracetamol outside the USA) is one of the most commonly used drugs which has known hepatotoxicity. The goal of the present study was to examine whether CIH increases liver injury, hepatic oxidative stress and inflammation induced by chronic APAP treatment. Adult C57BL/6J mice were exposed to CIH or intermittent air (IA) for 4 weeks. Mice in both groups were treated with intraperitoneal injections of either APAP (200 mg kg(-1)) or normal saline daily. A combination of CIH and APAP caused liver injury, with marked increases in serum alanine aminotransferase, aspartate aminotransferase (AST), gamma-glutamyl transferase and total bilirubin levels, whereas CIH alone induced only elevation in serum AST levels. Acetaminophen alone did not affect serum levels of liver enzymes. Histopathology revealed hepatic necrosis and increased apoptosis in mice exposed to CIH and APAP, whereas the liver remained intact in all other groups. Mice exposed to CIH and APAP exhibited decreased hepatic glutathione in conjunction with a fivefold increase in nitrotyrosine levels, suggesting formation of toxic peroxynitrite in hepatocytes. Acetaminophen or CIH alone had no effect on either glutathione or nitrotyrosine. A combination of CIH and APAP caused marked increases in pro-inflammatory chemokines, monocyte chemoattractant protein-1 and macrophage inflammatory protein-2, which were not observed in mice exposed to CIH or APAP alone. We conclude that CIH and chronic APAP treatment lead to synergistic liver injury, which may have clinical implications for patients with OSA.

[Effects of interleukin-18 and hypoxia-inducible factor-1α in serum and gingival tissues of rat model with periodontitis exposed to chronic intermittent hypoxia].

PubMed

Wang, Bin; Wang, Xiaoqin

2015-08-01

This study evaluates the expression of interleukin-18 (IL-18) and hypoxia-inducible factor (HIF)-lα in rat periodontitis model exposed to normoxia and chronic intermittent hypoxia (CIH) environments. The possible correlation between periodontitis and obstructive sleep apnea-hypopnea syndrome (OSAHS) was also investigated. Methods: Thirty-two Sprague-Dawley (SD) rats were randomly assigned into four groups: normoxia control, normoxia periodontitis, hypoxia control, and hypoxia periodontitis groups. The periodontitis models were established by ligating the bilateral maxillary second molars and employing high-carbohydrate diets. Rats in hypoxia control and hypoxia periodontitis groups were exposed to CIH treatment mimicking a moderately severe OSAHS condition. All animals were sacrificed after eight weeks, and the clinical periodontal indexes were detected. The levels of IL-18 and HIF-1α in serum and gingival tissues were determined using enzyme-linked immunosorbent assay (ELISA). The correlation between attachment loss (AL) and the levels of IL-18 and HIF-lα in hypoxia periodontitis group was evaluated. The levels of IL-18 and HIF-lα in hypoxia periodontitis group were significantly higher than that in normoxia periodontitis and hypoxia control groups (P<0.05). Furthermore, the levels of IL-18 and HIF-lα in serum (r-0.792, r=0.753, P<0.05) and gingival tissues (r-0.817, r=0.779, P<0.05) were positively correlated with AL. CIH could aggravate the destruction of periodontal tissues, which is correlated with IL-18 and HIF-lα levels.

Chronic diseases and mortality among immigrants to Israel from areas contaminated by the Chernobyl disaster: a follow-up study.

PubMed

Slusky, Danna A; Cwikel, Julie; Quastel, Michael R

2017-05-01

To examine six chronic diseases and all-cause mortality among immigrants to Israel from areas contaminated by the Chernobyl accident. The medical data were obtained from the two largest HMOs in Israel. In the assessment of chronic diseases, individuals were divided into three groups: less exposed (n = 480), more exposed (n = 359), and liquidators (n = 45) and in the mortality analysis, into two groups: less exposed (n = 792) and more exposed (n = 590). Compared to the less exposed, adults from the more exposed group had increased odds of respiratory disorders (OR = 2.34, 95% CI 1.21, 4.54) and elevated odds, with borderline significance, of ischemic heart disease (OR = 2.01, 95% CI 0.97, 4.20). In addition, the liquidators had increased odds of hypertension compared to the less exposed (OR = 2.64, 95% CI 1.24, 5.64). The Cox proportional-hazards model indicated no difference in the ratio of all-cause mortality between the exposed groups during the follow up period. Our study, conducted approximately two decades after the accident, suggests that exposure to radionuclides may be associated with increased odds of respiratory disorders and hypertension.

Contaminant mixtures interact to impair predator-avoidance behaviours and survival in a larval amphibian.

PubMed

Sievers, Michael; Hale, Robin; Swearer, Stephen E; Parris, Kirsten M

2018-06-14

Global declines in amphibian populations are a significant conservation concern, and environmental contamination is likely a contributing driver. Although direct toxicity may be partly responsible, contaminants are often present at sub-lethal concentrations in the wild. Behavioural end-points are becoming an increasingly useful method to estimate the impact of contaminants, particularly if the behavioural responses manifest to affect individual fitness (i.e. survival, growth, or reproduction). In the wild, most animals are affected by multiple stressors, and determining how these interact to affect behaviour is critical for understanding the ecological implications of contaminant exposure. Here, we examined the individual and interactive effect of the heavy metal copper and the insecticide imidacloprid on mortality rates and anti-predator behaviours of spotted marsh frog (Limnodynastes tasmaniensis) tadpoles. This common species frequently occupies and breeds in contaminated stormwater and agricultural wetlands, where copper and imidacloprid are often present. These contaminants may alter behaviour via physiological and neurological pathways, as well as affecting how tadpoles respond to chemical cues. Tadpoles suffered unexpectedly high mortality rates when exposed to imidacloprid concentrations well below published LC50 concentrations. Only unexposed tadpoles significantly avoided predator cues. Copper and imidacloprid reduced swimming speed and distance, and escape responses, while increasing erratic swimming. We observed an interactive effect of imidacloprid and copper on erratic swimming, but in general imidacloprid and copper did not act synergistically. Our results suggest that as contaminants enter waterbodies, tadpoles will suffer considerable direct mortality, reduced foraging capacity, and increased susceptibility to predation. Our results provide the first evidence of imidacloprid affecting amphibian behaviour, and highlight both the adverse effects of

[Effects of α-lipoic acid and vitamin C on oxidative stress in rat exposed to chronic arsenic toxicity].

PubMed

Liu, Chong-Bin; Feng, Yan-Hong; Ye, Guang-Hua; Xiao, Min

2010-12-01

To explore arsenic-induced oxidative stress and the protective efficacy of α-lipoic acid and vitamin c. 50 male SD rats were randomly divided into 5 groups. Ten rats (the control group) were exposed to deionized water for 6 weeks, and the others were alone exposed to sodium arsenite (50 mg/L water) for 6 weeks, at the same time, three group rats were administered intragastrically (i.g.) with α-lipoic acid 10 mg×kg(-1)×d(-1) and vitamin C 25 mg×kg(-1)×d(-1) either alone or in combination. At the end of experiment, blood was drawn from abdominal aorta, and then the blood, brain and liver of rats were used for biochemical assays, including blood glutathione (GSH), δ-aminolevulinic acid dehydratase (δ-ALAD ), reactive oxygen species (ROS) and oxidized glutathione (GSSG) level. At the same time, the super oxide dismutase (SOD) activity, glutathione peroxidase (GSH-Px) activity, catalase (CAT) activity, ATPase activity of brain and liver were determined. The caspase activity of brain were also determined. There were a significant increase in ROS level (P < 0.05), but a significant decrease in δ-ALAD activity (P < 0.01) in the chronic arsenic toxicity model group compared with the control group. These alterations were marginally restored by co-administration of vitamin C and α-lipoic acid individually, while significant recovery was observed in the animals supplemented with both the antioxidants together with arsenite in rat (P < 0.05). At the same time, there was a significant increase in the ROS and TBARS level of the brain and liver (P < 0.05), and caspase activity of the brain (P < 0.05), while there was a significant decrease in antioxidant enzymes and ATPase activity on arsenite exposure in rats (P < 0.05). These alterations were also marginally restored by co-administration of vitamin C and α-lipoic acid individually, while significant recovery was observed in the animals supplemented with both the antioxidants together with arsenite in rat (P < 0

Chronic Pain: How Challenging Are DDIs in the Analgesic Treatment of Inpatients with Multiple Chronic Conditions?

PubMed Central

Siebenhuener, Klarissa; Eschmann, Emmanuel; Kienast, Alexander; Schneider, Dominik; Minder, Christoph E.; Saller, Reinhard; Zimmerli, Lukas; Blaser, Jürg; Battegay, Edouard

2017-01-01

Background Chronic pain is common in multimorbid patients. However, little is known about the implications of chronic pain and analgesic treatment on multimorbid patients. This study aimed to assess chronic pain therapy with regard to the interaction potential in a sample of inpatients with multiple chronic conditions. Methods and Findings We conducted a retrospective study with all multimorbid inpatients aged ≥18 years admitted to the Department of Internal Medicine of University Hospital Zurich in 2011 (n = 1,039 patients). Data were extracted from the electronic health records and reviewed. We identified 433 hospitalizations of patients with chronic pain and analyzed their combinations of chronic conditions (multimorbidity). We then classified all analgesic prescriptions according to the World Health Organization (WHO) analgesic ladder. Furthermore, we used a Swiss drug-drug interactions knowledge base to identify potential interactions between opioids and other drug classes, in particular coanalgesics and other concomitant drugs. Chronic pain was present in 38% of patients with multimorbidity. On average, patients with chronic pain were aged 65.7 years and had a mean number of 6.6 diagnoses. Hypertension was the most common chronic condition. Chronic back pain was the most common painful condition. Almost 90% of patients were exposed to polypharmacotherapy. Of the chronic pain patients, 71.1% received opioids for moderate to severe pain, 43.4% received coanalgesics. We identified 3,186 potential drug-drug interactions, with 17% classified between analgesics (without coanalgesics). Conclusions Analgesic drugs-related DDIs, in particular opioids, in multimorbid patients are often complex and difficult to assess by using DDI knowledge bases alone. Drug-multimorbidity interactions are not sufficiently investigated and understood. Today, the scientific literature is scarce for chronic pain in combination with multiple coexisting medical conditions and medication

Bumblebee learning and memory is impaired by chronic exposure to a neonicotinoid pesticide

PubMed Central

Stanley, Dara A.; Smith, Karen E.; Raine, Nigel E.

2015-01-01

Bumblebees are exposed to pesticides applied for crop protection while foraging on treated plants, with increasing evidence suggesting that this sublethal exposure has implications for pollinator declines. The challenges of navigating and learning to manipulate many different flowers underline the critical role learning plays for the foraging success and survival of bees. We assessed the impacts of both acute and chronic exposure to field-realistic levels of a widely applied neonicotinoid insecticide, thiamethoxam, on bumblebee odour learning and memory. Although bees exposed to acute doses showed conditioned responses less frequently than controls, we found no difference in the number of individuals able to learn at field-realistic exposure levels. However, following chronic pesticide exposure, bees exposed to field-realistic levels learnt more slowly and their short-term memory was significantly impaired following exposure to 2.4 ppb pesticide. These results indicate that field-realistic pesticide exposure can have appreciable impacts on learning and memory, with potential implications for essential individual behaviour and colony fitness. PMID:26568480

Immune-escape mutations and stop-codons in HBsAg develop in a large proportion of patients with chronic HBV infection exposed to anti-HBV drugs in Europe.

PubMed

Colagrossi, Luna; Hermans, Lucas E; Salpini, Romina; Di Carlo, Domenico; Pas, Suzan D; Alvarez, Marta; Ben-Ari, Ziv; Boland, Greet; Bruzzone, Bianca; Coppola, Nicola; Seguin-Devaux, Carole; Dyda, Tomasz; Garcia, Federico; Kaiser, Rolf; Köse, Sukran; Krarup, Henrik; Lazarevic, Ivana; Lunar, Maja M; Maylin, Sarah; Micheli, Valeria; Mor, Orna; Paraschiv, Simona; Paraskevis, Dimitros; Poljak, Mario; Puchhammer-Stöckl, Elisabeth; Simon, François; Stanojevic, Maja; Stene-Johansen, Kathrine; Tihic, Nijaz; Trimoulet, Pascale; Verheyen, Jens; Vince, Adriana; Lepej, Snjezana Zidovec; Weis, Nina; Yalcinkaya, Tülay; Boucher, Charles A B; Wensing, Annemarie M J; Perno, Carlo F; Svicher, Valentina

2018-06-01

HBsAg immune-escape mutations can favor HBV-transmission also in vaccinated individuals, promote immunosuppression-driven HBV-reactivation, and increase fitness of drug-resistant strains. Stop-codons can enhance HBV oncogenic-properties. Furthermore, as a consequence of the overlapping structure of HBV genome, some immune-escape mutations or stop-codons in HBsAg can derive from drug-resistance mutations in RT. This study is aimed at gaining insight in prevalence and characteristics of immune-associated escape mutations, and stop-codons in HBsAg in chronically HBV-infected patients experiencing nucleos(t)ide analogues (NA) in Europe. This study analyzed 828 chronically HBV-infected European patients exposed to ≥ 1 NA, with detectable HBV-DNA and with an available HBsAg-sequence. The immune-associated escape mutations and the NA-induced immune-escape mutations sI195M, sI196S, and sE164D (resulting from drug-resistance mutation rtM204 V, rtM204I, and rtV173L) were retrieved from literature and examined. Mutations were defined as an aminoacid substitution with respect to a genotype A or D reference sequence. At least one immune-associated escape mutation was detected in 22.1% of patients with rising temporal-trend. By multivariable-analysis, genotype-D correlated with higher selection of ≥ 1 immune-associated escape mutation (OR[95%CI]:2.20[1.32-3.67], P = 0.002). In genotype-D, the presence of ≥ 1 immune-associated escape mutations was significantly higher in drug-exposed patients with drug-resistant strains than with wild-type virus (29.5% vs 20.3% P = 0.012). Result confirmed by analysing drug-naïve patients (29.5% vs 21.2%, P = 0.032). Strong correlation was observed between sP120T and rtM204I/V (P < 0.001), and their co-presence determined an increased HBV-DNA. At least one NA-induced immune-escape mutation occurred in 28.6% of patients, and their selection correlated with genotype-A (OR[95%CI]:2.03[1.32-3.10],P = 0.001). Finally

Toxicity of endosulfan to tadpoles of Fejervarya spp. (Anura: Dicroglossidae): mortality and morphological deformities.

PubMed

Devi, Ngangom Nganbi; Gupta, Abhik

2013-11-01

The acute toxicity of endosulfan to the tadpoles of three coexisting species of the anuran genus Fejervarya revealed 96 h LC50 values of 46.715, 6.596, and 3.015 μg l(-1) for Fejervarya sp.1, F. teraiensis and Fejervarya sp.2, respectively. Toxicity of endosulfan was also tested at the sublethal concentrations of 5 and 0.5, and 0.3 and 0.03 μg l(-1) (c 10 and 1% of their respective 96 h LC50 values) in Fejervarya sp.1 and Fejervarya sp.2, and 0.35 and 0.18 μg l(-1) (c 5 and 2.5% of 96 h LC50) in F. teraiensis. Endosulfan was observed to cause mortality at concentrations as low as c 1, 2.5 and 10% of their respective 96 h LC50 values in Fejervarya sp.2, F. teraiensis, and Fejervarya sp.1. Such vulnerabilities are likely to have implications for the survival of natural populations of these co-existing species as well as other anurans present in the study area where pesticide use is relatively high in the tea plantations. Morphological deformities caused by endosulfan comprised failure to develop one or both forelimb in Fejervarya sp.1 and F. teraiensis, stunted hindlimb growth in Fejervarya sp.1, and axial malformation in Fejervarya sp.1 and Fejervarya sp.2. Fore- and hind-limb deformities were likely to have occurred due to the impairment of thyroid metabolism by endosulfan. These effects illustrate the threat that continued endosulfan use poses to natural populations of anuran amphibians.

Behavioral effects of chronic adolescent stress are sustained and sexually dimorphic

PubMed Central

Bourke, Chase H.; Neigh, Gretchen N.

2011-01-01

Evidence suggests that women are more susceptible to stress-related disorders than men. Animal studies demonstrate a similar female sensitivity to stress and have been used to examine the underlying neurobiology of sex-specific effects of stress. Although our understanding of the sex-specific effects of chronic adolescent stress has grown in recent years, few studies have reported the effects of adolescent stress on depressive-like behavior. The purpose of this study was to determine if a chronic mixed modality stressor (consisting of isolation, restraint, and social defeat) during adolescence (PND37-49) resulted in differential and sustained changes in depressive-like behavior in male and female Wistar rats. Female rats exposed to chronic adolescent stress displayed decreased sucrose consumption, hyperactivity in the elevated plus maze, decreased activity in the forced swim test, and a blunted corticosterone response to an acute forced swim stress compared to controls during both adolescence (PND48-57) and adulthood (PND96-104). Male rats exposed to chronic adolescent stress did not manifest significant behavioral changes at either the end of adolescence or in adulthood. These data support the proposition that adolescence may be a stress sensitive period for females and exposure to stress during adolescence results in behavioral effects that persist in females. Studies investigating the sex-specific effects of chronic adolescent stress may lead to a better understanding of the sexually dimorphic incidence of depressive and anxiety disorders in humans and ultimately improve prevention and treatment strategies. PMID:21466807

Subchronic Toluene Exposure alters Retinal Function in Long Evans Rats: Experimental Evidence Supporting Observations from Studies of Exposed Humans.

EPA Science Inventory

Studies of humans chronically exposed to volatile organic solvents commonly report impaired visual functions, including low contrast sensitivity and reduced color discrimination. These reports have been controversial, however, in part due to a lack of confirmation from controlled...

Early Intervention for Families Exposed to Chronic Stress and Trauma: The Attachment Vitamins Program

ERIC Educational Resources Information Center

Hulette, Annmarie C.; Dunham, Mackenzie; Davis, Mindy; Gortney, Jason; Lieberman, Alicia F.

2016-01-01

This article describes the Attachment Vitamins program, a trauma-informed parent group intervention for families with young children. Attachment Vitamins is a relational psychoeducational intervention based on the principles of Child-Parent Psychotherapy (CPP). Its goal is to repair the impact of chronic stress and trauma through strengthening the…

Genetic and maternal effect influences on viability of common frog tadpoles under different environmental conditions.

PubMed

Pakkasmaa, S; Merilä, J; O'Hara, R B

2003-08-01

The influence of environmental stress on the expression of genetic and maternal effects on the viability traits has seldom been assessed in wild vertebrates. We have estimated genetic and maternal effects on the viability (viz probability of survival, probability of being deformed, and body size and shape) of common frog, Rana temporaria, tadpoles under stressful (low pH) and nonstressful (neutral pH) environmental conditions. A Bayesian analysis using generalized linear mixed models was applied to data from a factorial laboratory experiment. The expression of additive genetic variance was independent of pH treatments, and all traits were significantly heritable (survival: h2 approximately 0.08; deformities: h2 approximately 0.26; body size: h2 approximately 0.12; body shape: h2 approximately 0.14). Likewise, nonadditive genetic contributions to variation in all traits were significant, independent of pH treatments and typically of magnitude similar to the additive genetic effects. Maternal effects were large for all traits, especially for viability itself, and their expression was partly dependent on the environment. In the case of body size, the maternal effects were mediated largely through egg size. In general, the results give little evidence for the conjecture that environmental stress created by low pH would impact strongly on the genetic architecture of fitness-related traits in frogs, and hamper adaptation to stress caused by acidification. The low heritabilities and high dominance contributions conform to the pattern typical for traits subject to relatively strong directional selection.

The toxicity of glyphosate alone and glyphosate-surfactant mixtures to western toad (Anaxyrus boreas) tadpoles.

PubMed

Vincent, Kim; Davidson, Carlos

2015-12-01

Pesticide choice based on toxicity to nontarget wildlife is reliant on available toxicity data. Despite a number of recent studies examining the effects of glyphosate on amphibians, very few have aimed to understand the toxicological effects of glyphosate in combination with surfactants as it is commonly applied in the field. Land managers interested in making pesticide choices based on minimizing impacts to nontarget wildlife are hindered by a lack of published toxicity data. Short-term acute toxicity trials were conducted for glyphosate in the form of isopropylamine salt (IPA) alone and mixed with 2 surfactants: Agri-dex and Competitor with western toad (Anaxyrus [Bufo] boreas) tadpoles. Glyphosate IPA mixed with Competitor was 6 times more toxic than glyphosate IPA mixed with Agri-dex, and both mixtures were more toxic than glyphosate IPA alone. The median lethal concentrations reported for 24-h and 48-h exposures were 8279 mg/L (24 h) and 6392 mg/L (48 h) for glyphosate IPA alone; 5092 mg/L (24 h) and 4254 mg/L (48 h) for glyphosate IPA mixed with Agri-dex; and 853 mg/L (24 h) and 711 mg/L (48 h) for glyphosate IPA mixed with Competitor. The present study indicates that the toxicity of a tank mix may be greatly increased by the addition of surfactants and may vary widely depending on the specific surfactant. © 2015 SETAC.

Cognitive impairment in agricultural workers and nearby residents exposed to pesticides in the Coquimbo Region of Chile.

PubMed

Corral, Sebastián A; de Angel, Valeria; Salas, Natalia; Zúñiga-Venegas, Liliana; Gaspar, Pablo A; Pancetti, Floria

2017-07-01

Chronic exposure to organophosphate pesticides is a worldwide public health concern associated with several psychiatric disorders and dementia. Most existing studies on the effects of pesticides only evaluate agricultural workers. Therefore, this study sought to establish if individuals indirectly exposed to pesticides, such as residents in agricultural areas, also suffer cognitive impairments. Neuropsychological evaluations were carried out on three groups (n=102): agricultural workers directly exposed to pesticides (n=32), individuals living in agricultural areas indirectly (i.e. environmentally) exposed to pesticides (n=32), and an unexposed control group (n=38). The assessed cognitive processes included memory, executive functions, attention, language praxis, and visuoconstruction. The direct exposure group performed significantly lower in executive function, verbal fluency, and visual and auditory memory tests than the indirect exposure group, which, in turn, performed worse than the unexposed group. Even after adjusting for age, gender, and educational level, both exposure groups showed higher rates of cognitive deficit than control individuals. In conclusion, both direct and indirect chronic exposure to pesticides affects cognitive functioning in adults and, consequently, actions should be taken to protect the health of not only agricultural workers, but also of residents in agricultural areas. Copyright © 2017 Elsevier Inc. All rights reserved.

Decline of arbuscular mycorrhizal fungi in northern hardwood forests exposed to chronic nitrogen additions