Small Frogs Research Articles

Respiration and lactate production in isolated frog skeletal muscle: Effects of passive stretch

1. 1. The effects of varying degrees of passive stretch on in vitro oxygen consumption and intracellular lactate efflux have been investigated in paired recti abdomini muscles from small male frogs. 2. 2. Oxygen consumption [mm 3 (STP)/mg (dry wt)/hr] was found to be linearly related to load ( r = 0.98), increasing from 1.57 ± 0.11 (SE) at 2 g to 2.30 ± 0.18 at 10 g, 2.89 ± 0.16 at 20g and 3.26 ± 0.21 at 30 g. 3. 3. Lactate released into the medium [μM/g (dry wt)/hr] was inversely related to load ( r = −0.52), increasing initially from 36.84 ± 3.28 (SE) at 2 g to 108.55 ± 12.9 at 10 g, then abruptly decreasing with additional loading (18.10 ± 2.60 at 20g and 11.71 ± 2.80 at 30 g). 4. 4. Results suggest that as stretch-related oxidative energy metabolism increases, there is a lessening dependence on anaerobic energy-yielding processes.

Hyla ruschiin.sp., a New frog from the Atlantic Forest Domain in the state of Espirito Santo, Brazil (Amphibia, Hylidae)

ruschii n.sp., a small frog tentatively included into the Hyla parviceps group”;, is described from the Atlantic Mountain Domain around Santa Teresa, State of Espirito Santo, Brasil.

Choosing the Right Pond: Human Behavior and the Quest for Status

Is it better to be a big frog in a small pond or a small frog in a big pond? In this lively and original book, the author argues persuasively that people's concerns about status permeate and profoundly alter a broad range of human behaviour. He takes issue with his fellow economists for too often neglecting fundamental elements in human nature in their study of how people make basic economic choices.

New Species of Minute Leptodactylid Frogs from the Andes of Ecuador and Peru

--A new species of Phyllonastes (P. heyerl) is named from the Andean ridges in the Huancabamba Depression in southern Ecuador and northern Peru. A similar species is described as a new species of Phrynopus (P. bagrecito) from the Andes of Cuzco, Peru. Based on the similarities in skeletons, Phyllonastes may share a common ancestry with frogs of the Phrynopus peruvianus group. An additional record is provided for Adelophryne adiastola (Amazonas, Colombia). A suite of minute (adults less than 20 mm SVL) leptodactylid frogs has been described from the lowlands of northern South America and along the eastern Andean flanks in Ecuador (Lynch, 1976; Heyer, 1977; Hoogmoed and Lescure, 1984). Lynch (1976) described the first two as species of the genus Euparkerella (previously known only from southeastern Brazil). Heyer (1977) placed these two species in a new genus (Phyllonastes) and named another new genus (Phyzelaphryne) from Amazonian Brazil. Lynch (1980) treated Phyzelaphryne miriamae as a synonym of Eleutherodactylus nigrovittatus. Lastly, Hoogmoed and Lescure (1984) revalidated Phyzelaphryne miriamae and proposed a new genus with two new species (Adelophryne). At present, all of these minute frogs are placed in the tribe Eleutheradactylini. The five Amazonian species are placed in three genera: Adelophryne (A. adiastola and A. gutturosa), Phyllonastes (P. lochites and P. myrmecoides), and Phyzelaphryne (P. miriamae). These small frogs are rather imperfectly known, being separated generically on the basis of (1) presence/absence of vomerine dentition, (2) presence/absence of a tarsal tubercle, (3) digits flattened/round in cross section, and (4) reduction of fourth finger of hand (sometimes with reduction in number of phalanges). Hoogmoed and Lescure (1984) suggested that Adelophryne and Phyzelaphryne might be closely related because each has a peculiar form to the digital pads (lateral grooves not united at tip). They cautioned however that it was difficult to distinguish features that reflect adaptation to a leaf-litter habitat from t ose that are correlates of achieving very small size from those reflecting relationships. As Hoogmoed and Lescure noted, these frogs are all quite rare and too few specimens are available to permit skeletal preparations. The two new species described here are represented by sufficient material to permit osteological preparations. MATERIALS AND METHODS Specimens are identified with a catalogue number and museum abbreviation (following list in Leviton et al., 1980). Measurements were made with dial calipers (under magnification) and recorded to the nearest 0.1 mm. Specimens were cleared and stained (Alizarin and Alcian Blue) using the methods of Dingerkus and Uhler (1977). All drawings were made using a Wild M-5 with a drawing tube attachment. Terminology and measurements follow Lynch (1975).

Aspects of the Life History and Ecology of the Desert Night Snake, Hypsiglena torquata deserticola: Colubridae, in Southwestern Idaho

Aspects of the Life History and Ecology of the Desert Night Snake, Hypsiglena torquata deserticola: Colubridae, in Southwestern Idaho

Adaptations of the reed frog Hyperolius viridiflavus (Amphibia, Anura, Hyperoliidae) to its arid environment : I. The skin of Hyperolius viridiflavus nitidulus in wet and dry season conditions.

Hyperolius viridiflavus nitidulus inhabits parts of the seasonally very hot and dry West African savanna. During the long lasting dry season, the small frog is sitting unhidden on mostly dry plants and has to deal with high solar radiation load (SRL), evaporative water loss (EWL) and small energy reserves. It seems to be very badly equipped to survive such harsh climatic conditions (unfavorable surface to volume ratio, very limited capacity to store energy and water). Therefore, it must have developed extraordinary efficient mechanisms to solve the mentioned problems. Some of these mechanisms are to be looked for within the skin of the animal (e.g. protection against fast desiccation, deleterious effects of UV radiation and overheating). The morphology of the wet season skin is, in most aspects, that of a "normal" anuran skin. It differs in the organization of the processes of the melanophores and in the arrangement of the chromatophores in the stratum spongiosum, forming no "Dermal Chromatophore Unit". During the adaptation to dry season conditions the number of iridophores in dorsal and ventral skin is increased 4-6 times compared to wet season skin. This increase is accompanied by a very conspicuous change of the wet season color pattern. Now, at air temperatures below 35° C the color becomes brownish white or grey and changes to a brilliant white at air temperatures near and over 40° C. Thus, in dry season state the frog retains its ability for rapid color change. In wet season state the platelets of the iridophores are irregularly distributed. In dry season state many platelets become arranged almost parallel to the surface. These purine crystals probably act as quarter-wave-length interference reflectors, reducing SRL by reflecting a considerable amount of the radiated energy input.EWL is as low as that of much larger xeric reptilians. The impermeability of the skin seems to be the result of several mechanisms (ground substance, iridophores, lipids, mucus) supplementing each other.The light red skin at the pelvic region and inner sides of the limbs is specialized for rapid uptake of water allowing the frog to replenish the unavoidable EWL by using single drops of dew or rain, available for only very short periods.

A tetrodotoxin-like substance found in the Brazilian frog Brachycephalus ephippium

A tetrodotoxin-like substance, denoted ephippiotoxin, was obtained from the tissues of Brachycephalus ephippium, a small pumpkin-coloured frog collected in the Atlantic Forest of the southeast region of Brazil. Ephippiotoxin is a dialyzable substance soluble in water, methanol and ethanol, but insoluble in organic solvents such as chloroform and other apolar solvents. After treatment with active charcoal (Norit-A) and purification with ion-exchange Amberlite IRC-50 resin (NH 4 + form), a freeze-dried residue was obtained, with a toxicity of c. 117 μg/kg (mice, i.p.). Ephippiotoxin showed the same mobility as crystalline tetrodotoxin (Sankyo) when submitted to thin-layer chromatography (silica gel G) using seven different solvent systems. White mice (20 ± 1 g) injected i.p. with either B. ephippium tissue extracts or semi-purified toxin showed partial paralysis of the hind limbs, lethargy, altered breathing rhythm and clonic convulsions. Death occurred within 1.5 – 30 min after injection, depending on the dose. Ephippiotoxin induced atrioventricular diastolic blockade in the toad heart. It also inhibited the response of toad striated muscle to direct and indirect electric stimulation and blocked the compound action potential of isolated frog sciatic nerve.

3-Trifluoromethyl-4-nitrophenol (TFM) Control of Tadpoles in Culture Ponds

Abstract In definitive 96-hour toxicity tests, the LC50 for TFM to small bullfrog larvae was 1.39 mg/L compared to 5.50 mg/L for fathead minnows. Also, the 96-hour LC90 for TFM to bullfrog tadpoles was 2.31 mg/L and the LC10 for TFM to fathead minnows was 3.40 mg/L. On-site toxicity tests in three ponds using containers filled with pond water demonstrated that large and small bullfrog and green frog (R. clamitans) larvae were more sensitive to TFM than fathead minnows or bluegill (Lepomis macrochirus).

Productivity of herded ducks in West Java

Throughout Indonesia, ducks are kept primarily for egg production. Particularly in Java and Bali, a large proportion of the flocks are kept under a traditional form of management whereby they are herded through recently harvested rice fields for feeding. Observations were made on two flocks of Tegal-type ducks in West Java, emphasis being given to factors influencing egg production. The average egg production was 41.3% and 26·9% (average per duck per day calculated from total production for all ducks for one year). The rate of production through the year varied widely and only rarely reached the level obtained when the same breed is well managed under intensive conditions. The feed obtained by ducks from rice fields was predominantly rice and snails. The average composition of the diet, obtained from an analysis of crop contents, was rice, 77.2%; snails, 17.4%; insects, 1.0%; grasses,, 0.5%; small frogs, 0.2%: crustacea, 0.1% and unidentified materials, 3.6%. No supplementary feed was provided. Both availability and composition of the diet were important factors affecting productivity. In addition, such factors as the effect of transporting birds to a new feeding area and the experience and diligence of the herdsman all significantly influence the actual or potential egg production of fully herded flocks.

Glycogen utilization in isolated frog muscle: An effect of passive mechanical stretch

1. 1. The effect of passive mechanical stretch on glycogen utilization and total protein maintenance in paired sartorii muscles from small male frogs has been investigated, in vitro. 2. 2. Glycogen content of stretched muscles decreased 72.6% over a 24-hr incubation period, compared to a 23.1% decline in unstretched control muscles. 3. 3. Stretched muscles retained 54.7% of their total protein content over a 24-hr period, compared to 38.4% in the unstretched control muscles. 4. 4. Unstretched muscles demonstrated a significant (11.1%) increase in wet weight following 24 hr of incubation, presumably due to increased water retention. There were no significant changes in the wet wts of stretched muscles.

Accuracy of sound localization by the frog Hyperolius marmoratus

The sound localization ability of female painted reed frogs was studied by phonotactic approaches via a three‐dimensional grid to an elevated loudspeaker (through which male mating calls were broadcast). Females readily resolved the sound source elevation with a mean jump error angle of 37&° (26 trials, 17 females), compared to a mean jump error angle of 19° (33 trials, 13 females) for a more conventional two‐dimensional ground approach. Lateral head scanning, often accompanied by vertical changes in head orientation, frequently preceded successive jumps. The ability of such small frogs to accurately localize a sound source in both the horizontal and vertical plane, given the absence of a pinna or external canal, is remarkable. [This study was supported by the South African Council for Scientific and Industrial Research, and the Animal Research Program, University of the Witwatersrand.]

Occurrence of skin alkaloids in non-dendrobatid frogs from Brazil (Bufonidae), Australia (Myobatrachidae) and Madagascar (Mantellinae)

J. W. Daly, R. J. Highet and C. W. Myers. Occurrence of skin alkaloids in non-dendrobatid frogs from Brazil (Bufonidae), Australia (Myobatrachidae) and Madagascar (Mantellinae). Toxicon 22, 905 – 919, 1984.—Several taxa of small frogs from the southern hemisphere contain alkaloids similar or identical to compounds previously known only from neotropical poison frogs of the family Dendrobatidae. Skin of the Brazilian toad Melanophryniscus moreirae (family Bufonidae) contains a new alkaloid 8-hydroxy-8-methyl-6-(5′-hydroxy-2′-methyl-hexylidene)-1- azabicyclo-[4.3.0]nonane (C 16H 29NO 2), which is designated pumiliotoxin 267C. Such a structure is typical of the pumiliotoxin-A class of dendrobatid alkaloids. Melanophryniscus moreirae contains smaller quantities of an alkaloid (C 19H 33NO 3) identical in chromatographic and mass spectral properties to the dendrobatid alkaloid allopumiliotoxin 323B. Allopumiliotoxin 323B and an isomer of 267C occur with unidentified alkaloids in skin of the Australian frog Pseudophryne semimarmorata (family Myobatrachidae) and also in the skin of the Madagascan frog Mantella aurantiaca (family Ranidae, subfamily Mantellinae). In addition to new compounds, Mantella aurantiaca and M. madagascariensis also contain other alkaloids (e.g. histrionicotoxin and pumiliotoxin B) that were known previously only in dendrobatid frogs. Such alkaloids have not been detected in a phylogenetically wide array of other anuran amphibians, and the dendrobatid alkaloids thus become an evolutionary enigma. Certain of these compounds may have arisen convergently from new biosynthetic pathways in several families of frogs, or these alkaloids may represent parallel expression of shared-primitive pathways that are unexpressed or lost in related frogs.

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-

Changes in the Food Niche during Postmetamorphic Ontogeny of the Frog Pseudacris triseriata

The food niche and foraging strategies of the chorus frog Pseudacris triseriata were investigated by examining the prey/predator size relationship as it relates to prey availability, and they were found to be dynamic from metamorphosis to adulthood. Snout to vent length of the frogs proved to be a good predictor of the mean size of prey taken. Relative availability of the different sized prey items in the environment was estimated from samples of potential prey obtained by suction sampling. This availability information was used in addition to the data on stomach contents to describe the foraging strategies of the different size classes of frogs. It was found that small frogs (- 17.0 mm) ate prey as they were encountered in the environment, and that large frogs (>23.1 mm) selected larger prey which were rarer in the community. Intermediate sized frogs (between 17.1 and 23.0 mm) were characterized by an intermediate pattern. Intermediate frogs consumed large numbers of prey per unit time, and the possibility that this facilitated rapid growth is discussed. The mean maximum prey size increased with increasing frog size, but leveled off for the largest size classes, whereas mean minimum prey size continued to increase with increasing frog size. The large frogs were selective in their diet as they apparently chose the more optimal (in terms of benefits and costs of pursuit, capture and consumption) sized prey while they discriminated against the smaller prey. This ontogenetic pattern of foraging strategies is somewhat unique among predators for which there exists information in the literature, and it is suggested that the small body size (<30 mm) of P. triseriata relative to the size of their prey (terrestrial arthropods) allows this pattern.

Cooperative effect of calcium ions in mediator release from neuromuscular synapses of large and small frog sartorius muscle fibers

Cooperative effect of calcium ions in mediator release from neuromuscular synapses of large and small frog sartorius muscle fibers

Small mode miniature end plate potentials are increased and evoked in fatigued preparations and in high Mg 2+ saline

Amplitude histograms of miniature end-plate potentials (MEPPs) from small sartorius fibers (6–20 μm diam.) of very small frogs were found to have multiple peaks. All MEPPs had the same time characteristics which demonstrates that they arose at the same junction. The amplitude of the smallest mode (s-MEPPs) was one-seventh that of the major mode (m-MEPPs), and in the unstressed preparation s-MEPPs composed only a few per cent of the total. After repetitive nerve stimulation (1 min at 20 Hz) the percentage of s-MEPPs was initially increased. Successive periods of stimulation gradually reduced the end-plate potential (EPP) (above 90% failures) to the same size as s-MEPPs. A 12.5mMMg 2+ and half normal Ca 2+ saline was also found to increase the percentage of s-MEPPs and reduce EPPs so that profiles of EPP amplitude histograms showed a class of small EPPs the same size as s-MEPPs. The data demonstrate that quanta the size of s-MEPPs were released with nerve stimulation in both the Mg 2+ blocked and fatigued preparation.

Activity coefficients of intracellular Na+ and K+ during development of frog oocytes

The chemical activities, (a), of Na+ and K+ were determined in large mature and in small immature frog oocytes, using open-tipped micropripettes and ion-selective microelectrodes. The average chemical concentrations, c, of Na+ and K+ were determined by spectrophotometry and by electron probe X-ray microanalysis. The apparent activity coefficient (gammaapp) was calculated for each ion as the ratio, a/c. With development, (aNa/ak) decreased four to fivefold and (cNa/cK) increased six to sevenfold. In the large mature oocytes, gammaapp was measured to be 0.08 +/- 0.02 and gammaappK lay within the range 1.15 +/- 0.03 to 1.29 +/- 0.04, constituting the smallest value for Na+ and largest value for K+, respectively, thus far reported. This intracellular value of gammaappK was substantially greater than the activity coefficient of K+ in the external medium (0.76). The data suggest that the inequality of gammaappNa and gammaappK in this and probably other cells reflects the development of subcellular compartmentalization of ions. Possible intracellular sites of ionic compartmentalization are considered.

Small pet aquarium frogs as a source of Salmonella.

Salmonellae were isolated from 21% of the samples of freshwater aquarium frogs tested and from 25% of the samples of aquarium water containing these frogs. The salmonellae were Salmonella arizonae, S. bovis-morbificans, S. hadar, S. saint-paul, S. typhimurium, and S. worthington. These isolations were made over a period of 9 months and from three different cities. This association of salmonellae with frogs may contribute to cases of human salmonellosis since other aquarium species have already been shown to contribute to such cases.

The Food and Food Habits of Blanchard's Cricket Frog, Acris crepitans blanchardi (Amphibia, Anura, Hylidae), in Iowa

Stomach contents of 218 Blanchard's cricket frogs were analyzed relative to frog size, reproductive status, size of fat bodies, sex, and date. Food consumption was found to be greater in larger frogs, reproducing frogs, frogs with small fat bodies, female frogs, and June-July frogs. Experiments on rate of food passage through the stomach were conducted on 181 additional cricket frogs. Handling was found to inhibit digestion but in large cages constructed in the frogs' natural environment, food passed through stomachs in 8 hours. All frogs in their natural environment fed throughout the day and night and only 4 were found with empty stomachs during the study. Annual consumption of food by Iowa cricket frogs was estimated.

Electrical characteristics of frog atrial trabeculae in the double sucrose gap

The electrical behavior of small single frog atrial trabeculae in the double sucrose gap has been investigated. The currents injected during voltage clamp experiments did not behave as predicted from the assumption of spatial uniformity of the voltage across a Hodgkin-Huxley membrane. Much of the difference is due to the geometrical complexities of this tissue. Nonetheless, two transient inward currents have been identified, the faster of which is blocked by tetrodotoxin (TTX). The magnitude of the slower transient varies markedly between preparations but always increases in a given preparation with increase of external calcium. The fast transient current traces, at small to intermediate depolarizations, are often marred by the presence of notches and secondary peaks due most probably to the loss of space clamp conditions. In many preparations these could be removed by reducing the current magnitude through application of a partially-blocking dose of TTX. Conversely, in the preparations whose fast transient was fully blocked by TTX, notches and secondary peaks in the slow transient could by induced through increasing calcium concentration and thereby the slow current magnitude. Previously used techniques for the measurement of the reversal potential of the fast inward transient have been shown to be invalid. In so far as they can be measured, the reversal potentials of the fast and slow inward transient are in the same neighborhood, i.e. around 120 mV from rest. The true values may be quite a bit apart. The total charge flow in the capacitive transient was measured for different sized nodes and preparations. From these data and estimates of plasma membrane area per unit trabecular volume, specific membrane capacitances of around 3 muF/cm2 were calculated for small bundles. The apparent ion current densities on this basis are approximately 1/10 of those measured in axons. The capacitive current occurring in small bundles decayed as the sum of at least three exponential functions of time. On the basis of these data and the anomalously large stable node widths, we suggest a coaxial core model of the preparation with the inner elements in series with an additional large extracellular resistance.