Female Frogs Research Articles

Invasive toads adopt marked capital breeding when introduced to a cooler, more seasonal environment

Abstract Amphibians from cold and seasonal environments show marked capital breeding and sustained resource allocation to growth when compared with conspecifics from warmer, less seasonal environments. Capital breeding fuels reproduction by using only stored energy, and larger sizes and masses confer higher fecundity, starvation resistance and heat and water retention. Invasive populations act as experiments to explore how resources are allocated in novel environments. We investigated resource allocation of the southern African toad Sclerophrys gutturalis in a native source population (Durban) and in an invasive population recently (< 20 years) established in a cooler, more seasonal climate (Cape Town). After dissection, lean structural mass (bones and muscles), gonadal mass, liver mass and body fat percentage were measured in 161 native and invasive animals sampled at the beginning and the end of the breeding season. As expected, female gonadal mass decreased throughout the breeding season only in the invaded range. Thus, invasive female toads adopt a more marked capital breeding strategy than native conspecifics. Conversely, males from both populations appear to be income breeders. Also, male and female toads from the invaded range allocate more resources to growth than their native counterparts. Such a novel allocation strategy might be a response to the low temperatures, reduced rainfall and heightened seasonality encountered by the invasive population.

Effects of information load on response times in frogs and bats: mate choice vs. prey choice

Decisions tend to become more challenging as the number of available options increases and choice sets become more complex. Choosing between multiple options may require additional information processing time and effort. Here, we asked if response time increases with stimulus number and attractiveness by female frogs (Physalaemus pustulosus) and their predators, frog-eating bats (Trachops cirrhosus), when comparing the mating calls of male tungara frogs. We found that frogs’ response time is significantly longer when presented with two calls, compared with one. Bats also take longer to respond when presented with two calls but only when they were complex calls. Although the frogs and bats behave somewhat similarly in this experiment, the decisions that these animals are making are occurring in different domains (mating vs. foraging) and have different fitness consequences. Given these differences, we find it especially interesting that for both frogs and bats, we see similar temporal patterns in response times as a function of information load. SIGNIFICANCE STATEMENT: Animals are often faced with several options simultaneously. One cost of decision-making is the time involved in choosing the best option within a choice set. Here, we asked whether female frogs and frog-eating bats take longer to respond when presented multiple frog mating calls simultaneously. We also asked whether the attractiveness of those frog calls influences the time it takes frogs and bats to respond to them. We found that the time to respond was influenced by both the number and attractiveness of frog calls for both bats and frogs; however, frog response time seemed to be more greatly influenced by the number of frog calls, while bat response time seemed to be more influenced by the attractiveness of frog calls. In general, our results suggest that there may be similar mechanisms involved in decision-making for both animals.

At the invasion front, male cane toads (Rhinella marina) have smaller testes.

As a colonizing species expands its range, individuals at the invasion front experience different evolutionary pressures than do those at the range-core. For example, low densities at the edge of the range mean that males should rarely experience intense sperm competition from rivals; and investment into reproduction may trade-off with adaptations for more rapid dispersal. Both of these processes are predicted to favour a reduction in testis size at the invasion front. To explore effects of invasion stage in Australian cane toads (Rhinella marina), we collected and dissected 214 adult males from three regions: one in the species' range-core (northeastern Australia), and two from invasion fronts (one in northwestern Australia and one in southeastern Australia). Despite the brief duration of separation between toads in these areas (approx. 85 years), testis masses averaged greater than 30% higher (as a proportion of body mass) in range-core males than in conspecifics sampled from either vanguard of the invasion. Previous work has documented low reproductive frequencies in female cane toads at the invasion front also, consistent with the hypothesis that evolutionary and ecological pressures unleashed by an invasion can favour relatively low resource allocation to reproduction in both sexes.

Comparative Histological Observation of Liver Tissue Before and After Reproduction in Male and Female Frogs (Pelophylax ridibundus)

Histomorphological structure of the liver of Ranidae species during the reproduction period contribute significantly to the production rate in the frog culture studies. In this study, the cytoplasmic status of hepatocytes, lipid and melanin pigment in liver parenchyma of adult male and female Pelophylax ridibundus (Pallas, 1771) were investigated before and after reproduction. For histological studies, adult frogs were collected from nature and placed in production ponds to examine the reproduction process. In this study, twenty four breeding male frogs, with average weight 36.63±12.84 g and length 69.29±9.15 mm, and twenty four breeding females with average weight and length of 56.61±19.59 g and 79.54±7.07 mm were used. Samples from the liver tissue of frog were taken in 2015 during (March) and after reproduction (June) period. Histologically pictures of liver parenchyma were taken from the as homogeneous fields as possible. Before the reproduction, it was found that the liver parenchyma of the female frogs were cytoplasmically intense, with a low amount of melanin pigment and lipid droplets. Similarly, male frogs liver parenchyma and hepatocytes were found to be cytoplasmically intense, containing a low amount of melanin pigment and lipid droplets. Both female and male frogs completed the reproduction in April and May. After reproduction period, a great amount of melanin pigment in the liver parenchyma was observed and the cytoplasmic density of the hepatocytes decreased. As a result, cytoplasmic decrease in hepatocytes, structural changes and increase in melanin pigments supports the idea that glycogen and lipids stored in the liver parenchyma are used for reproduction.

Specific activation of the hb4 gene in the Xenopus oocyte through a Nobox-binding element located at the proximal promoter sequence.

We isolated and characterized Xenopus tropicalis hb4 flanking DNA and showed that the -3076/+29 sequence was able to drive stage-specific transcription in the developmental process. Transgenic reporter analysis indicated that green fluorescent protein was expressed in the ovaries of female frogs at 3 months of age and in both the ovaries and testis of frogs at 6 months of age. A series of experiments with deletion of the flanking sequence and a subsequent luciferase reporter assay revealed that there were two positive regulatory regions and that the most proximal sequence of the promoter region had a certain level of transcriptional activity in oocytes. Subsequently, we showed that a conserved sequence containing Nobox-binding element (NBE) was essential for transcriptional activation and that Nobox expressed in the ovary had a crucial role in hb4 transcription through the NBE sequence.

Neotropical dancing frog: the rich repertoire of visual displays in a hylodine species

During reproductive season, males usually must defend their territory against competitor males and attract females for reproduction. Acoustic signals evolved as an alternative to physical attacks, thus reducing injuries to both opponents during a territorial dispute, but they are also the primarily trait used by female frogs to select males. However, there is some recent evidence that visual signalling also can be important during social interactions in frogs. Here, for the first time, we describe the sophisticated visual behaviour of Hylodes meridionalis, a diurnal species that is endemic to the southern Atlantic Forest, where it inhabits fast streams. We submitted resident males to mirror self-image presentations to simulate the presence of an intruder male in their territories. Furthermore, we collected observations from close-range interactions between individuals of this very shy species. We observed seven types of visual displays: toe flagging (slow up-and-down movements of one or more toes), arm lifting (rapid up-and-down movements of one arm), leg lifting (rapid up-and-down movements of one leg), arm waving (lifting an arm and waving it in an arc), both legs kicking (rapidly stretching both hind limbs towards the back), foot flagging (slowly raising one hind limb in a semi-arch movement) and throat display (pulsation of one or both paired lateral vocal sacs without sound production). Only the kicking of both legs was displayed exclusively by females; toe flagging and foot flagging were displayed by males only during agonistic interactions. The frequency of visual displays (7 types, 117 events) was much greater than that of acoustic signals (3 types, 66 events). Our data demonstrate that the visual repertoire of the genus Hylodes is richer than previously noted and that visual display behaviour in anurans could be more common than previously believed. Therefore, this characterisation study aids our understanding of the function of the rich repertoire of visual displays in frog species and highlights that ethologists should be directing more of their attention towards this poorly explored anuran behaviour.

Oviposition and father presence reduce clutch cannibalism by female poison frogs

BackgroundThe consumption of conspecific young by adult individuals is a common phenomenon across various animal taxa. Possible adaptive benefits of such behaviour include the acquisition of nutrients, decreased competition for one’s own offspring, and/or increased mating opportunities. Clutch cannibalism has occasionally been observed in several species of Neotropical poison frogs, but the circumstances under which this behaviour occurs has rarely been investigated experimentally. Recent experiments with the poison frog Allobates femoralis have shown that males indiscriminately transport all clutches located inside their own territory to bodies of water, but become highly cannibalistic when taking over a new territory. Females are able to indirectly discriminate between their own and foreign clutches by location and take over transport duties of their own clutches only in the absence of the father. Cannibalism by A. femoralis females has not been previously observed. We thus asked if, and under which circumstances, cannibalism of unrelated clutches by female A. femoralis would occur, by manipulating the presence of the clutch’s father, the female’s own reproductive state, and the female’s familiarity with the environment.ResultsFemales clearly cannibalize foreign clutches. Cannibalism was most pronounced when the female had not recently produced her own clutch and the father of the foreign clutch was absent. The female’s familiarity with the area had no significant influence on the likelihood of cannibalism to occur.ConclusionsOur data indicate that both previous oviposition and the father’s presence reduce cannibalistic behaviour in A. femoralis females. Cannibalistic females may gain nutritional benefits or enhanced inclusive fitness by preying on other females’ offspring. The finding that the father’s presence at the clutch site/territory was sufficient to reduce cannibalism by females suggests a prominent role of male territoriality for the evolution of male parental care.

Yenilebilir Su Kurbağası Pelophylax ridibundus (Pallas, 1771)'un Dişi ve Erkek Bireylerinin Karkas Miktarı Açısından Karşılaştırılması

Doğadan toplanan erkek ve dişi kurbağaların (Pelophylax ridibundus), boy uzunluğu (SVL) ve arka bacak uzunluğu ile karkas, arka bacak, deri, baş ve karaciğer ağırlığı alınarak karkas miktarı belirlenmeye çalışılmıştır. Dişi kurbağaların ortalama SVL değeri 91,6±0,53 mm, erkeklerin 81,1±0,69 mm olarak ölçülerek, aradaki farkın istatiksel açıdan önemli olduğu tespit edilmiştir. Gıda olarak tüketilen arka bacakların ortalama uzunluk değerleri, dişi kurbağalarda 72,0±0,65 mm, erkek kurbağalarda 68,0±0,53 mm tespit edilmiş ve aradaki farkın istatiksel açıdan önemli olduğu görülmemiştir. Arka bacakların ortalama ağırlıkları dişi kurbağalarda 21,45±5,06 g, erkek kurbağalarda 15,53±2.94 g olduğu ve her iki cinsiyette de bu miktarların toplam vücut ağırlığının yaklaşık %25‘ine denk geldiği belirlenmiştir. Çalışma esnasında dişi kurbağaların sırasıyla vücut, karkas ve gıda olarak tüketilen arka bacaklarının ortalama ağırlıkları, erkek kurbağalara göre daha yüksek miktarda tespit edilmiş olup; dişi kurbağalar ile erkek kurbağalar arasındaki bu ağırlık farkları aynı zamanda istatistiksel açıdan önemli bulunmuştur. Karkas ağırlıkları, hem dişi hem de erkek bireylerde toplam ağırlığın yaklaşık olarak %50‘sini oluşturmaktadır. Kesim işlemi sonucunda karkas dışında kalan; deri, baş ve karaciğerin ortalama ağırlıkları dişi kurbağalarda erkek kurbağalara oranla daha fazla miktarda bulunmuştur. Dişi ve erkek bireyler arasında baş ağırlığı hariç karkas dışında kalan diğer kısımlar arasındaki farkların önemli olduğu belirlenmiştir. Kurbağa derisi önemli bir sanayi ürünü olup, miktarı dişi kurbağalarda ortalama 8,07±2,04 g, erkek kurbağalarda ortalama 5,66±1,21 g bulunmuştur. Bu değerlerin oranı, toplam vücut ağırlığının %10‘una denk geldiği tespit edilmiştir. Bu çalışmada, dişi kurbağaların erkek kurbağalardan karkas kazancı bakımından daha iyi olduğu ve karkas miktarı dışında kalan, baş, karaciğer ve derinin miktarı tespit edilerek değerlendirilmesi araştırılmıştır.

Effect of perfluorooctanesulfonate exposure on steroid hormone levels and steroidogenic enzyme activities in juvenile Silurana tropicalis.

The impact of the perfluoro-chemical, perfluorooctanesulfonate (PFOS), on gonadal steroidogenesis during sexual differentiation in Silurana tropicalis was examined because of its ubiquity in the environment, bioaccumulative nature and potential to disturb endocrine activity. A partial life cycle study exposing S. tropicalis to varying concentrations of PFOS 0.06, 0.13, 0.25, 0.50 and 1.0mg PFOS/L [nominal]) was conducted. Gonad and plasma samples were collected from juvenile control specimens and organisms exposed to PFOS from early embryo through 150days post-metamorphosis. Gonad CYP17, aromatase and 5α-reductase activities were measured. Plasma estradiol, testosterone, dihydrotestosterone (DHT) and gonadal testosterone were measured in both males and females. Increased plasma DHT and gonadal testosterone were found in PFOS-treated juvenile male S. tropicalis compared to controls. Decreased plasma estradiol, but not testosterone, was detected in PFOS-treated female S. tropicalis compared to controls. Plasma DHT was not detected and an increase in gonadal testosterone was detected in PFOS-treated female frogs. Female S. tropicalis exposed to PFOS exhibited a concentration-related decrease in the mean aromatase activity, but not 5α-reductase. PFOS exposure in male frogs induced a concentration-related increase in 5α-reductase activity, but did not alter aromatase activity compared to control frogs. A concentration-related increase in CYP 17,20-lyase activity, but not 17-hydroxylase activity, was found in both female and male S. tropicalis exposed to PFOS.

Fatal phaeohyphomycosis due to Exophiala sp. infection in a free-living common toad Bufo bufo.

A wild adult female common toad Bufo bufo found dead in Scotland in September 2016 was observed to have hepatomegaly, a large soft tissue mass in the coelomic cavity (2.7 g, 3.5 × 2.3 × 1.8 cm) and numerous dark-red papules (1-2 mm diameter) in the skin and subjacent tissue over the back and dorsal aspects of the limbs. Histopathological examination identified marked hepatitis and coelomitis associated with pigmented fungal hyphae, which are results consistent with a diagnosis of phaeohyphomycosis. Sequencing of the internal transcribed spacer region and the D1-D2 region of the large subunit of the ribosomal RNA gene from affected liver tissue identified the presence of Exophiala (Chaetothyriales) sp., a black yeast previously identified as a cause of amphibian phaeohyphomycosis. To our knowledge, this is the first published report of Exophiala sp. in a wild or captive amphibian in Europe and the first description of phaeohyphomycosis affecting a free-living amphibian in Great Britain. Exophiala spp. are saprobes and opportunistic pathogens. It has been postulated that phaeohyphomycosis is a disease of immunocompromised amphibians; however, we found no evidence of significant concurrent infection or generalised debility in this common toad. Phaeohyphomycosis appears to be a sporadic cause of mortality in amphibians, and this report adds to the growing list of pathogens known to affect wild amphibians in Europe.

Energy harvesting from a bio cell

This work shows experimentally how electrical energy can be harvested directly from cell membrane potential and used to power a wireless communication. The experiment is performed by exploiting the membrane potential of Xenopus oocytes taken from female frogs. Electrical potential energy of the membrane is transferred to a capacitor connected to the cell via a proper electrical circuit. Once the capacitor has reached the planned amount of energy, the circuit is disconnected from the cell and the stored energy is used to power a radio frequency communication that carries bio-sensed information to a distanced receiving circuit. Our result shows that electrical energy can be harvested directly from biological cells and used for a number of purposes, including wireless communication of sensed biological quantities to a remote receiving hub.

Female frogs prefer city slickers

Female frogs prefer city slickers

Demographic and Morphometric Characteristics of the Moor Frog Rana arvalis from a Transformed Habitat in the Khanty-Mansi Autonomous Region—Yugra

We analyzed the variations in the demographic and morphological characteristics of mature Rana arvalis individuals from natural and transformed habitats near Surgut. Female frogs from the transformed habitat were significantly smaller than males and significantly younger and smaller than females from the natural habitat. The direction of sex-related differences in both populations was the same as in most of the populations of the species that had been studied earlier. The low values of the mean body length (but not age) that were recorded in populations living near the northern range limit correspond to the general trend of body size variation in adult frogs in relation to the length of the season of activity throughout its vast range. Sex-related differences in most of the studied characteristics were due only to the variations in body size; few characteristics are not dependent on the body size, and these characteristics are most likely to determine mating success in males. We observed no morphological differences related to different environmental conditions in both neighboring populations. The relative femur and shin lengths were significantly larger in males than in females not only in the two Surgut populations but in all other populations studied earlier; these differences were not related to the greater body length in males. A tendency toward an increase in the relative head width and a decrease in the relative femur and shin lengths from the southern to the northern populations was observed in both sexes; this tendency was related to neither the mean age nor the body length.

An evaluation of intestinal parasites in edible frogs (<i>Hoplobatracus</i> spp) sold for consumption in Zaria, Kaduna State, Nigeria

To determine the presence of eggs, oocysts and larvae of intestinal parasites in edible frogs (Hoplobatrachus species) sold for human consumption in Hanwa Zaria, Kaduna State, Northwestern Nigeria. Gastrointestinal tract (GIT) samples of edible frogs (n = 225) were collected from the frog market (FM) at Hanwa, Zaria. The samples were analysed for parasites eggs, oocysts and larvae using zinc sulphate-sucrose floatation method of specific gravity 1.21, sedimentation tests followed by microscopy. Parasitic eggs, larvae, and oocyst were found in 54.7% of the total gastrointestinal tract samples using floatation technique while, eggs were found in 40 (17.8%) of the samples using sedimentation technique. The overall prevalence of the parasitic oocyst, eggs or larva using the simple floatation and sedimentation techniques techniques in the examination of the frog was 63.1% (142/225). The presence of parasites in both the male and female frogs were 92 (75.4%) and 50 (48.5%), respectively, there was statistically significant association between gender and parasite prevalence, P = 0.0001. There was no significant association between original location of frogs and prevalence of parasites, but there was statistically significant association between gender and parasite prevalence, p = 0.525. Coccidia oocysts mean counts were highest (8.11 ± 0.423). People should be educated on how to prevent possible zoonotic transmission to humans during capture, slaughter, processing and/or consumption of raw or improperly cooked frogs.Keywords: Frog, Hoplobatrachus spp, eggs, oocysts, larvae, Zaria

Lipid accumulation responses in the liver of Rana nigromaculata induced by perfluorooctanoic acid (PFOA)

Perfluorooctanoic acid (PFOA) is a perfluorinated compound that is widely distributed, is persistent in the environment, and has a low-level chronic exposure effect on human health. The aim of this study was to investigate the peroxisome proliferator activated receptors γ (PPARγ) and the sterol regulatory element-binding protein 2 (SREBP2) signaling pathways in regulating the lipid damage response to PFOA in the livers of amphibians. Male and female frogs (Rana nigromaculata) were exposed to 0, 0.01, 0.1, 0.5 and 1 mg/L PFOA. After treatment, we evaluated the pathological changes in the liver by Oil Red O, staining and examined the total cholesterol (T-CHO) and triglyceride (TG) contents. The mRNA expression levels of PPARγ, Fatty acid synthase (FAS), Acetyl-CoA carboxylase (ACC), Glycerol-3-phosphate acyltransferase (GPAT), SREBP2 and 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) were measured by quantitative real-time polymerase chain reaction (qRT-PCR). The administration of PFOA caused marked lipid accumulation damage in the amphibian livers. The T-CHO contents were elevated significantly after PFOA treatment; these results show a dose-dependent manner in both sexes. The TG content showed a significant increase in male livers, while it was elevated significantly in female livers. The RT-PCR results showed that the mRNA expression levels of PPARγ, ACC, FAS, GPAT, SREBP2 and HMG-CoA were significantly dose-dependently increased in the PFOA-treated groups compared with those of the control group. Our results demonstrated that PFOA-induced lipid accumulation also affected the expression levels of genes FAS, ACC, GPAT and HMG-CoA in the PPARγ and SREBP2 signaling pathways in the liver. These finding will provide a scientific theoretical basis for the protection of Rana nigromaculata against PFOA effects.

The Waiting and Mating Game: Condition Dependent Mate Sampling in Female Gray Treefrogs (Hyla versicolor)

Strong sexual selection by receivers can lead to the evolution of elaborate courtship behaviors in signalers. However the process by which receivers sample signalers and execute mate choice under complex signaling conditions—and thus the realized strength of sexual selection—is poorly understood. Moreover, receivers can vary in condition, which can further influence mate sampling strategies. Using wild female frogs we tested two hypotheses at the intersection of these important problems: that some of the individual variation in mate sampling is explained by (1) the reproductive urgency hypothesis, which predicts that receivers in a more urgent reproductive state will sample mates less and/or (2) the reproductive investment hypothesis, which predicts that receivers that have invested less in the current reproductive effort will sample mates less. Eastern gray treefrogs, Hyla versicolor, were collected in amplexus and repeatedly tested for phonotaxis behavior using a dynamic playback assay. To evaluate if hormonal mechanisms explained variation in the mate sampling, three steroid hormones, estradiol, progesterone, and corticosterone, were collected using a noninvasive water-borne hormone assay, validated for this species in the present study. Finally, we measured clutch size (investment) and the duration of time required for each female to oviposit after being reunited with their male mate (urgency). We found repeatability in many of the behaviors, including mate sampling. We found that females with higher concentrations estradiol and corticosterone made quicker choices, and that females with higher progesterone sampled mates more. We also found that female frogs in a more urgent reproductive state had lower concentrations of progesterone and estradiol, thereby providing the first evidence of a relationship between gonadal hormones and reproductive urgency. Collectively we found some support for the reproductive urgency but not the investment hypothesis. Thus, even though a female frog’s reproductive readiness is a highly transient life history stage, fine scale variation in her reproductive timeline could mitigate the strength of directional selection.

Integrated analysis of mRNA and miRNA expression profiles reveals muscle growth differences between adult female and male Chinese concave-eared frogs (Odorrana tormota)

The Chinese concave-eared torrent frog (Odorrana tormota) is the first known non-mammalian vertebrate that can communicate using ultrasound. In this species, females are approximately four times as large as males, in which the female growth rate is obviously higher than that of male. Until now, the molecular mechanisms underlying muscle growth development differences between male and female frogs have not been reported. Here, we integrated mRNA and miRNA expression profiles to reveal growth differences in the hindlimb muscles of 2-year-old frogs. Among 569 differentially expressed genes (DEGs), 69 were associated with muscle growth and regeneration. Fifty-one up-regulated genes in females were potentially involved in promoting muscle growth and regeneration, whereas 18 up-regulated genes in males may lead to muscle growth inhibition and fast-twitch muscle fiber contraction. 244 DEGs were enriched in mTOR and other protein synthesis signaling pathways, and protein degradation pathways, including lysosomal protease, calpain, caspase, and ubiquitin–proteasome system pathways. It may interpret why female muscles grow faster than males. Based on expression differences of genes involved in glycolysis and oxidative metabolism, we speculated that the proportion of slow muscle fiber was higher and that of fast muscle fiber was lower in female compared with male muscle. Additionally, 767 miRNAs were identified, including 217 new miRNAs, and 6248 miRNA-negatively regulated mRNAs were predicted. The miRNA target genes were enriched in pathways related to muscle growth, protein synthesis, and degradation. Thus, in addition to the identified mRNA differential expressions, miRNAs may play other important roles in the differential regulation of hindlimb muscle growth between female and male O. tormota.

Dechlorane Plus flame retardant in a contaminated frog species: Biomagnification and isomer-specific transfer from females to their eggs

While flame retardant Dechlorane Plus (DP) and its dechlorinated analogs have been frequently detected in wildlife, knowledge is limited on their bioaccumulation and maternal transfer in amphibians. In the present study, the occurrence of syn- and anti-DP isomers and a DP dechlorinated compound, anti-Cl11-DP, were investigated in frogs and insects collected from the paddy field of a highly contaminated site. The concentrations of ∑DP (the sum concentrations of syn- and anti-DP) in the frog muscle, liver, and eggs were 141 ± 24.7, 454 ± 73.9, and 184 ± 31.1 ng/g lipid weight, respectively; with significantly higher levels in the males than females. The syn-, anti- and anti-Cl11-DP were all detectable in the frog eggs, demonstrating their maternal transfer in female frogs. The concentration ratios between eggs and liver pairs were 0.49 ± 0.01, 0.35 ± 0.01, and 0.53 ± 0.06 for syn-DP, anti-DP, and anti-Cl11-DP, respectively. The values of fanti (the concentration of anti-DP relative to the sum concentration of DP) differed significantly between frog tissues (0.33–0.79) and insects (0.71–0.74), indicating isomer-specific bioaccumulation of DP in the frogs. The concentration ratios of the frogs to the insects were greater than 1 for all the DP-related compounds, suggesting a possibility of biomagnification of these chemicals in the frogs.

Thyroid hormones and androgens differentially regulate gene expression in testes and ovaries of sexually mature Silurana tropicalis

A series of ex vivo exposures using testicular and ovarian tissues of sexually mature Western clawed frogs (Silurana tropicalis) were designed to examine molecular mechanisms of thyroid hormone (TH) and androgen crosstalk sans hypophyseal feedback as well as investigate potential sex-specific differences. Tissues were exposed ex vivo to either triiodothyronine (T3), iopanoic acid (IOP), one co-treatment of IOP + 5α-dihydrotestosterone (5α-DHT), 5α-DHT, 5β-dihydrotestosterone (5β-DHT), or testosterone (T). Direct exposure to different androgens led to androgen specific increases in thyroid receptor and deiodinase transcripts in testes (trβ and dio1) but a decrease in expression in ovaries (trβ and dio3), suggesting that male and female frogs can be differently affected by androgenic compounds. Moreover, exposure to select androgens differentially increased estrogen-related transcription (estrogen receptor alpha (erα) and aromatase (cyp19)) and production (estradiol) in ovaries and testes indicating the activation of alternate metabolic pathways yielding estrogenic metabolites. Sex-steroid-related transcription (i.e., steroid 5α-reductase type 2 (srd5α2) and erα) and production (i.e., 5α-DHT) were also differentially regulated by THs. The presence and frequency of transcription factor binding sites in the putative promoter regions of TH- and sex steroid-related genes were also examined in S. tropicalis, rodent, and fish models using in silico analysis. In summary, this study provides an improved mechanistic understanding of TH- and androgen-mediated actions and reveals differential transcriptional effects as a function of sex in frogs.

Taxonomic survey of water frog populations of Pelophylax bedriagae (Anura: Ranidae) in western Iran: a morphometric and bioacoustic approach

We explored the population systems of Pelophylax bedriagae (Camerano, 1882) in northwestern, western and southwestern Iran. Statistical significance for a hypothesis of sexual dimorphism of the frogs was tested using t-test and multivariate analysis of variances (MANOVA). Due to lack of sexual differences between the male and female frogs, the data of both sexes were pooled for further analysis. Taxonomic relationships among local populations were investigated using discriminate analysis (by stepwise method) with iterative sample assignment. The multivariate morphometric analyses revealed that the range of P. bedriagae extends to western Iran. The next step was to analyze the advertisement call (five standard parameters: call duration, number of pulse groups per call, duration of pulse groups, interval between pulse groups, and intercall interval) of the water frogs inhabiting three sites in western Iran. Rigorous application of the bioacoustic method removes all doubt that these three sites are inhabited by the same species, which on the basis of priority of nomenclature should be called P. bedriagae.