Mountain Chicken Research Articles

Intestinal Adenocarcinoma in a Montserrat Mountain Chicken (Leptodactylus fallax)

The mountain chicken ( Leptodactylus fallax ) is a critically endangered, exceptionally large frog, found only on the Caribbean islands of Montserrat and Dominica. A wild-caught adult female Montserrat mountain chicken housed at the Zoological Society of London was euthanased after a history of lethargy and loss of body weight. On gross pathology, a 1 cm diameter mass was seen in the wall of the large intestine and a 2 mm diameter nodule was present on the cranial pole of the left kidney. On histopathological examination, both masses were identified as adenocarcinomas. Comparison of the histological appearance of the two masses, and characteristics on special staining, suggest that it was an intestinal adenocarcinoma with metastatic spread to the kidney. In mountain chickens, the only neoplasms previously reported are two cases of ovarian dysgerminoma. No aetiology was detected in the case described here. However, we recommend vigilance for future cases in this species, to ensure the success of the breeding programme and the survival of the species.

Verification of specific selection SNPs between broiler and layer chicken in Chinese indigenous chicken breeds.

The direction of production for indigenous chicken breeds is currently unknown and this knowledge, combined with the development of chicken genome-wide association studies, led us to investigate differences in specific loci between broiler and layer chicken using bioinformatic methods. In addition, we analyzed the distribution of these seven identified loci in four Chinese indigenous chicken breeds, Caoke chicken, Jiuyuan chicken, Sichuan mountain chicken, and Tibetan chicken, using DNA direct sequencing methods, and analyzed the data using bioinformatic methods. Based on the results, we suggest that Caoke chicken could be developed for meat production, while Jiuyuan chicken could be developed for egg production. As Sichuan mountain chicken and Tibetan chicken exhibited large polymorphisms, these breeds could be improved by changing their living environment.

Conservation and historical biogeography: How did the mountain chicken frog get to the Caribbean?

Leptodactylus fallax, commonly known as the mountain chicken frog, is a large terrestrial frog currently found on two islands in the Caribbean. Habitat destruction, overhunting and disease outbreaks have contributed to declining population numbers. In order to identify appropriate conservation strategies, the historic geographic distribution of this frog must first be determined. Because no archeological evidence exists, this was accomplished by reviewing historical documents and inspecting museum collections. Inaccuracies in location and species names were identified in documents as well as in the mislabeling of museum specimens. Two means for natural immigration (dispersal and vicariance) and the artificial introduction by humans were considered. The authors concluded that the Amerindians transported L. fallax to eight islands throughout the Lesser Antilles as potential food resources as they colonized this area. The implication that 75% of the historical distribution is currently unoccupied by this species is considered in light of future reintroduction projects. Key words: Leptodactylus fallax, Amerindians, dispersal, vicariance.

Meeting ultraviolet B radiation requirements of amphibians in captivity: a case study with mountain chicken frogs (Leptodactylus fallax) and general recommendations for pre-release health screening.

Conservation breeding programmes are a tool used to prevent amphibian extinctions. The husbandry requirements of amphibians are complex. Ongoing research is needed to ensure optimal management of those captive-bred animals destined, in particular, for reintroduction. The UV-B and vitamin D3 requirements of amphibians are largely unknown. Metabolic bone disease has been reported in a number of species. These include the Critically Endangered mountain chicken frog (Leptodactylus fallax) reared in captivity on diets supplemented with a high-calcium multivitamin and mineral supplement containing vitamin D3 but without UV-B provision. Captive-bred L. fallax being reared for reintroduction to Montserrat were provided with UV-B radiation from metamorphosis and were fed on insects supplemented with vitamins and minerals. Overlapping heat, light and UV-B gradients were provided, mimicking what we believe best represents the natural situation and thereby facilitated self-regulation of UV-B exposure. A subset of 10 frogs was periodically radiographed to assess skeletal health. Radiographic bone density and anatomical integrity appeared unremarkable when compared with a wild caught L. fallax. In addition to other routine health-screening, we recommend that radiography be performed to a structured schedule on a subset of all captive-bred and reared amphibians to assess skeletal health and to gauge the appropriateness of captive husbandry. We demonstrate here that, through the appropriate provision of a combination of both UV-B radiation and dietary supplementation, L. fallax can be bred and reared in captivity with healthy skeletal development.

Genetic effects of melatonin receptor genes on chicken reproductive traits

The melatonin receptors are G protein-coupled receptors (GPCR) that bind melatonin. Three types of melatonin receptors have been cloned. The MTNR1A (or Mel1A or MT1) and MTNR1B (or Mel1B or MT2) receptor subtypes are present in humans and other mammals, while an additional melatonin receptor subtype MTNR1C (or Mel1C or MT3) has been identified in amphibians and birds. Previous research has shown that the three common melatonin receptors regulate physiological processes, including seasonal reproduction and ovarian physiology. However, whether or not any polymorphisms of the different melatonin receptor subtypes are associated with reproductive traits in chickens is not known. In this study, we performed candidate gene analysis to identify single-nucleotide polymorphisms (SNPs) in the MTNR1A, MTNR1B, and MTNR1C genes in the Erlang Mountain Chicken population. SNP discovery was achieved by sequencing pooled DNA samples. Direct PCR-sequencing, PCR-SSCP/PCR-sequencing, and PCR-RFLP method were used to genotype the MTNR1A, MTNR1B, and MTNR1C genes, respectively. The GLM Procedure was used to estimate the statistical significance of association between genotypes at each locus and reproductive traits of chickens. In a sample of 460 chickens, four novel polymorphisms (JQ249890:g.384T>C, JQ249891:g.387T>C, JQ249894:g.63C>T, and JQ249896:g.294G>A) were detected in the melatonin receptor genes MTNR1A, MTNR1B, and MTNR1C, respectively. A statistically significant association (P < 0.01) was found between two SNPs (MTNR1A SNP, MTNR1C SNP) and reproductive traits: egg number at 300 days of age (EN) and age at first egg (AFE).

Genetic effects of polymorphisms in the prolactin receptor gene on chicken reproductive traits

Prolactin receptor (PRLR) is a single transmembrane protein through which prolactin plays a wide variety of physiological roles in vertebrates. Markers of alleles for the PRLR gene were assessed for the association with six reproductive traits (bodyweight at first egg; egg weight at first egg; age at first egg; number of eggs at 300 days of age; bodyweight at 300 days of age; and egg weight at 300 days of age) in a single generation of the Erlang Mountain Chicken. Five single-nucleotide polymorphisms were detected in the PRLR gene by sequencing pooled DNA samples. Genotypes were identified using PCR-single strand conformational polymorphism and direct PCR-sequencing methods. The GLM procedure was used to estimate the association between genotypes and reproductive traits. The results showed that at the P1 locus, individuals with genotype TT had shorter age at first egg and greater number of eggs at 300 days of age than those with genotype CC (P < 0.01). Our findings suggest that the single-nucleotide polymorphism g.-14A > G at P1 locus could be a potential genetic marker for age at first egg and number of eggs at 300 days of age in the Erlang Mountain Chicken and haplotype ATGTT might be advantageous for reproductive traits.

Emergency procedures in the field: a report of wound treatment and fast healing in the giant ditch frog (Leptodactylus fallax)

AbstractA sub-adult, female, giant ditch frog (Leptodactylus fallax) (known locally as a mountain chicken) presented with a puncture of the coelomic cavity with partial intestinal evisceration. Improvised field treatment included replacement of the eviscerated intestines and closure of the wound using cotton-tipped applicator swabs. After seven days, the animal's injury appeared to be healed. During the rapid progression of the healing process, the animal showed no adverse effects. This report demonstrates a novel and successful field technique for wound treatment of a serious penetrating injury in an amphibian. It also shows a practical, feasible, and beneficial procedure that improved this animal's welfare and that might be appropriate under field conditions or if standard medical procedures cannot be followed.

Two remarkable prey items for a chicken:Leptodactylus fallaxMüller, 1926 predation upon the theraphosid spiderCyrtopholis femoralisPocock, 1903 and the colubrid snakeLiophis juliae(Cope, 1879)

Published records of amphibians preying on either large spiders or snakes in the wild are rare; this note documents predation by individuals of one amphibian species on both large spiders and snakes. Mountain chicken frogs (Leptodactylus fallax), which are amongst the largest frogs in the world, were observed successfully consuming the theraphosid spider Cyrtopholis femoralis on two occasions and attempting to consume another one on a further occasion on Montserrat. They were also found to have consumed the colubrid snake Liophis juliae on Dominica. This is the first theraphosid and the fourth snake species identified in the diet of L. fallax, and this frog is the first confirmed predator of C. femoralis.

Radiographic diagnosis of metabolic bone disease in captive bred mountain chicken frogs (Leptodactylus fallax)

Asymptomatic captive bred and wild-caught mountain chicken frogs (Leptodactylus fallax) were radiographed for evidence of metabolic bone disease (MBD). All 22 captive bred frogs had multiple folding fractures of long bones, decreased bone density, and cortical thinning, whereas none of the 11 wild-caught frogs had any radiographic evidence of MBD. These findings suggest that the nutritional requirements of L. fallax need to be examined for captive management purposes.

196 NONINVASIVE HORMONE MEASUREMENTS FOR GENDER IDENTIFICATION IN MONOMORPHIC ANURANS

Noninvasive techniques have been successful in distinguishing gender in dimorphic amphibian models (Szymanski DC et al. 2006 Zoo Biol. 25, 35-46). The aim of this study was to assess gender-specific fecal hormone metabolite concentrations in 2 dimorphic and 2 monomorphic, critically endangered species of amphibians to assist in ex situ breeding efforts. Fecal samples from 2 dimorphic anurans, the Puerto Rican Crested Toad (Bufo lemur) and the Wyoming Toad (Bufo baxteri) and 2 monomorphic species, the Mountain Chicken Frog (Leptodactylus fallax) and the Dusky Gopher Frog (Lithobates sevosa) were measured by enzyme immunoassay for sex-specific hormone differences (Student’s t-test; P < 0.05) among 6 variables (concentrations of estradiol (E2), progesterone (P), and testosterone (T), and ratios of P:E2, T:E2, and P:T). Values are presented as means ± SEM. Mountain Chicken Frog samples were obtained from individuals of known sex. Dusky Gopher Frog samples were from confirmed females but males were presumed based on subtle physical characteristics. The E2 concentrations (ng g-1) were significantly higher in females than males (P < 0.05) in all species except for the Dusky Gopher Frog. However, males in all 4 species, including the presumptive Dusky Gopher Frog males, exhibited significantly higher P:E2 and T:E2 ratios than females. Additionally, Wyoming Toad and Mountain Chicken Frog females had significantly higher P:T ratios than males (0.19 ± 0.05 v. 0.06 ± 0.00 and 0.34 ± 0.03 v. 0.20 ± 0.02, respectively). Similar to the American Toad (Szymanski et al. 2006), presumptive Dusky Gopher Frog males measured significantly higher T concentrations compared with females (376.4 ± 118.5 ng g-1 v. 174.0 ± 23.1 ngg-1, respectively). Although species-specific differences are apparent, fecal hormone measurements can be used to identify sex in monomorphic species and offer a potential tool for the captive breeding of endangered anurans. Table 1.

Digestibility and Mineral Availability of Phoenix Worms, Hermetia illucens, Ingested by Mountain Chicken Frogs, Leptodactylus fallax

ABSTRACT Soldier fly, Hermetia illucens, larvae have been introduced to the herpetoculture market as an alternative, palatable, high-calcium (Ca) foodstuff that minimizes or alleviates the need for additional gut-loading or dust supplements. Long-term successful breeding programs with insectivorous lizards and amphibians fed these larvae have been anecdotally reported; other observations suggest that whole larvae may pass intact and poorly digested through the gastrointestinal tract unless the cuticle is pierced. Feed intake and digestibility trials were conducted with 25 mountain chicken frogs, Leptodactylus fallax, housed in groups of five animals fed either crickets, or intact or mashed solider fly larvae to investigate nutrient availability. Diet significantly influenced the digestibility of dry matter, protein, fiber fractions, and all minerals (Ca, phosphorus [P], magnesium, sodium [Na], potassium [K], copper, iron, manganese, molybdenum, and zinc) measured in these trials (P< 0.01 for all nutrients...

Structure--activity study of the antibacterial peptide fallaxin.

Fallaxin is a 25-mer antibacterial peptide amide, which was recently isolated from the West Indian mountain chicken frog Leptodactylus fallax. Fallaxin has been shown to inhibit the growth of several Gram-negative bacteria including Enterobacter cloacae, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Here, we report a structure-activity study of fallaxin based on 65 analogs, including a complete alanine scan and a full set of N- and C-terminal truncated analogs. The fallaxin analogs were tested for hemolytic activity and antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-intermediate resistant S. aureus, (VISA), methicillin-susceptible S. aureus (MSSA), E. coli, K. pneumoniae, and P. aeruginosa. We identified several analogs, which showed improved antibacterial activity compared to fallaxin. Our best candidate was FA12, which displayed MIC values of 3.12, 25, 25, and 50 muM against E. coli, K. pneumoniae, MSSA, and VISA, respectively. Furthermore, we correlated the antibacterial activity with various structural parameters such as charge, hydrophobicity H, mean hydrophobic moment mu(H), and alpha-helicity. We were able to group the active and inactive analogs according to mean hydrophobicity H and mean hydrophobic moment mu(H). Far-UV CD-spectroscopy experiments on fallaxin and several analogs in buffer, in TFE, and in membrane mimetic environments (small unilamellar vesicles) indicated that a coiled-coil conformation could be an important structural trait for antibacterial activity. This study provides data that support fallaxin analogs as promising lead structures in the development of new antibacterial agents.

Mountain chickens Leptodactylus fallax and sympatric amphibians appear to be disease free on Montserrat

AbstractThe mountain chicken Leptodactylus fallax, the largest amphibian in the Caribbean, restricted to Dominica and Montserrat, is Critically Endangered. We investigated the presence of disease in the mountain chicken and in the sympatric cane toad Bufo marinus and Johnstone's whistling frog Eleutherodactylus johnstonei in the Centre Hills on Montserrat. Skin swabs of mountain chickens and B. marinus, and toe clips from E. johnstonei, were tested for Batrachochytrium dendrobatidis, the causative organism of cutaneous chytridiomycosis. Additionally, mountain chicken blood serum samples (n = 57) were examined for exposure to ranavirus. No chytrid or exposure to ranavirus was detected. We draw tentative conclusions about disease threats to the Montserrat mountain chicken population, and present preliminary recommendations for safeguarding this species.

OVARIAN DYSGERMINOMAS IN TWO MOUNTAIN CHICKEN FROGS (LEPTODACTYLUS FALLAX)

This report describes the gross, histologic, and immunohistochemical features of ovarian dysgerminomas in two adult female mountain chicken frogs (Leptodactylusfallax) from the same zoological institution. One frog was found dead, and the other frog had been ill for several days with a bloated abdomen and lethargy. On necropsy, large, pale multilobulated masses replaced the left ovary in both frogs, and one frog also had numerous smaller nodules scattered throughout the coelomic viscera. Histologically, these masses were composed of sheets and cords of polyhedral discrete germ cells consistent with the diagnosis of dysgerminoma. Neoplastic cells stained positive with immunohistochemistry for Oct4, which has been reported to detect stem cells including germ cells in a variety of species, including humans. Ovarian tumors are uncommonly encountered in both reptiles and amphibians, and this report is the first report of dysgerminoma in any amphibian species.

A report on the status of the herpetofauna of the Commonwealth of Dominica, West Indies

We review the status of the herpetofauna of the Commonwealth of Dominica, which is often cited as having the most complete extant herpetofauna of all the Lesser Antillean islands, a region which has suffered much historical extinction. Recent years have seen a number of threats of grave concern to island and regional endemic species, the chief of these being the arrival of chytridiomycosis on this island with negative effects on the mountain chicken Leptodactylus fallax, and the establishment of a non-native Greater Antillean anole, Anolis cristatellus, which has succeeded in displacing the native endemic Anolis oculatus from a part of the island in less than a decade.

Pentadactylin: An antimicrobial peptide from the skin secretions of the South American bullfrog Leptodactylus pentadactylus

Norepinephrine-stimulated skin secretions were obtained from male specimens of the South American bullfrog, Leptodactylus pentadactylus and shown to contain two peptides that inhibited the growth of microorganisms. The primary structure of a previously undescribed peptide, termed pentadactylin, was established as Gly-Leu-Leu-Asp-Thr-Leu-Lys-Gly-Ala-Ala-Lys-Asn-Val-Val-Gly-Ser-Leu-Ala-Ser-Lys-Val-Met-Glu-Lys-Leu.NH 2. The second peptide, which differs from pentadactylin by eight amino acid residues, is identical to fallaxin previously isolated from skin secretions of the Caribbean mountain chicken frog L. fallax. Pentadactylin inhibited the growth of reference strains of both Gram-negative bacteria ( Escherichia coli, Enterobacter cloacae, Klebsiella pneumoniae, Pseudomonas aeruginosa) and Gram-positive bacteria ( Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Streptococcus group B) but potencies were relatively low (MIC values in the range 25–200 μM). The peptide showed very low hemolytic activity against human erythrocytes (LD50 > 400 μM).

Characterization of a peptide from skin secretions of male specimens of the frog, Leptodactylus fallax that stimulates aggression in male frogs

During the breeding season of the mountain chicken frog Leptodactylus fallax, fighting between males results in the emergence of dominant animals that subsequently attract females to nesting sites. A peptide, termed Leptodactylus aggression-stimulating peptide (LASP), was isolated from norepinephrine-stimulated skin secretions from male specimens of L. fallax that was not present in skin secretions obtained from females. The primary structure of the peptide was established as: Gly-Leu-Trp-Asp-Asp-Leu-Lys-Ala-Ala-Ala-Lys-Lys-Val-Val-Ser-Ser-Leu-Ala-Ser-Ala-Ala-Ile-Glu-Lys-Leu NH 2. LASP had no pheromone-like action on females but had a chemoattractive effect on males and stimulated aggressive behaviors, such as rearing and leaping. It is suggested that this peptide may play an important role in initiating the competitive male–male interactions that are associated with the onset of reproductive behavior in L. fallax.

An antimicrobial peptide from the skin secretions of the mountain chicken frog Leptodactylus fallax (Anura:Leptodactylidae)

A 25 amino-acid-residue, C-terminally α-amidated peptide with antimicrobial activity, which has been termed fallaxin, was isolated in high yield from the norepinephrine-stimulated skin secretions of the mountain chicken frog Leptodactylus fallax (Anura:Leptodactylidae). The amino acid sequence of the peptide (Gly-Val-Val-Asp-Ile-Leu-Lys-Gly-Ala-Ala-Lys-Asp-Ile-Ala-Gly-His-Leu-Ala-Ser-Lys-Val-Met-Asn-Lys-Leu·NH 2) shows structural similarity with members of the ranatuerin-2 family previously isolated from the skins of frogs of the genus Rana that are only distantly related to the Leptodactylidae. This observation is consistent with the hypothesis that many frog skin antimicrobial peptides are related evolutionarily, having arisen from multiple duplications of an ancestral gene that existed before the radiation of the different families. Fallaxin inhibited the growth of reference strains of Gram-negative bacteria ( Escherichia coli, Pseudomonas aeruginosa, Enterobacter cloacae, Klebsiella pneumoniae) but with relatively low potency (MIC≥20 μM) and was inactive against the Gram-positive bacterium ( Staphylococcus aureus) and the yeast Candida albicans. The hemolytic activity of fallaxin was very low (HC 50>200 μM). A second peptide, comprising residues (1–22) of fallaxin, was also isolated from the skin secretions but this component was inactive against the microorganisms tested.

An Analysis of Prey Consumed by the Anuran, Leptodactylus fallax, From Dominica, West Indies

The prey consumed by Leptodactylus fallax were analyzed in regard to sex, body size, season of capture, prey weight, and prey length. The major food item, a cricket (Amphiacusta sp.), occurred in 59 percent of all frogs and comprised 21 percent of all items and 31 percent of total dry weight of food. Millipedes, coleopterans, and gastropods were also important groups of prey. Estimated mean caloric intake was higher in females (2.45 Kcal.) than in males (2.10 Kcal.) but was similar when adjusted for body weight. There was no appreciable difference between sexes in the mean length and mean number of prey items per frog. Frogs collected during the dry season contained more opilionids and vertebrates than those collected during the wet season; other types of prey were eaten in comparable amounts in both seasons. Mean prey length per frog in both sexes and mean dry weight of prey per frog, in females only, were positively, significantly correlated with mouth width; mean number of items per frog in both sexes was not. The largest frogs consumed a higher percentage of large items ( 40 mm) than smaller frogs, yet, in addition, consumed many small items (15 mm). Possible competition between large and small individuals and the lack of cannibalism are discussed. LEPTODACTYLUS FALLAX IS A TERRESTRIAL FROG now found only on the West Indian islands of Dominica and Montserrat. Little is known about its biology. Other than the original description under the name of L. dominicensis (Muller 1923), and subsequent re-naming (Muller 1925) since dominicensis was preoccupied for the genus Leptodactylus (Cochran 1923), the only mention of this species has been in faunal lists and in a paper by Westerman (1953:51) concerned with local extinctions. Leptodactylus fallax, known locally as the mountain chicken or crapaud, is a large frog; adults obtaining a mean snout-vent length (SVL) of 135 mm. It is closely related to the mainland species, L. pentadactylus, and is thought to have reached Dominica by rafting northward from Trinidad. On Dominica it is found in moist areas mainly on the leeward (westward) coast between the towns of Portsmouth in the north to Soufriere in the south, and from sea level to an altitude of approximately 310 m. On Montserrat it is found only at higher elevations (Blankenship, pers. comm., and pers. obs.). This report forms a portion of a life history study and is concerned with the food habits of L. fallax; a report on its reproductive cycle and growth is in prepara-