Observations on the oesophageal glands in some Tanzanian anurans

The occurrence and function of oesophageal glands In some anurans from Tanzania was investigated. The compound glands were present in the oesophageal submucosa of Ptychadena oxyrhynchus Smith, Ptychadena porosissima Steindachner, Phrynobatrachus acridoides Cope, Chiromantis xerampelina Peters, Leptopelis argenteus Pfeffer, Kassina maculata Dumeril, Afrixalus brachycnemis brachycnemis Boulenger, Hyperolius argus Peters, Hyperolius puncticulatus Pfeffer and Hyperolius tuberilinguis Smith, but were absent in Xenopus muelleri Peters, Bufo gutturalis Power and Phrynomerus bifasciatus bifasciatus Smith. It is suggested that in anurans, the oesophageal and gastric glands have similar functions.     

Using physiological conditions to assess current and future habitat use of a Subarctic frog

Species with especially close dependence on the environment to meet physiological requirements, such as ectotherms, are highly susceptible to the impacts of climate change. Climate change is occurring rapidly in the Subarctic and Arctic, but there is limited knowledge on ectotherm physiology in these landscapes. We investigated how environmental conditions and habitat characteristics influence the physiological conditions and habitat use of wood frogs (Rana sylvatica) in a Subarctic landscape near Churchill, Manitoba (Canada). We used plaster models to estimate water loss rates and surface body temperatures among different habitat types and at specific locations used by radio-tracked frogs. Water loss (R² = 0.67) and surface temperature (R² = 0.80) of plaster models was similar to that of live frogs. Model-based water loss rates were greater in tundra habitat than in boreal forest and ecotone habitat. Habitat use of wood frogs was strongly tied with available surface moisture and decreased water loss rates that were observed with plaster models. Environmental conditions, such as wind speed and ground temperature, explained 58% and 91% of the variation in water balance and temperature of plaster models. Maintaining physiological conditions may be challenging for semi-aquatic ectotherms in environments vulnerable to future climate change. The ability to predict physiological conditions based on environmental conditions, as demonstrated in our study, can help understand how wildlife will respond to climatic changes.     

A New Ranavirus Isolated from Pseudacris clarkii Tadpoles in Playa Wetlands in the Southern High Plains,Texas

Abstract

Mass die-offs of amphibian populations pose a challenging problem for conservation biologists. Ranaviruses often cause systemic infections in amphibians and, in North America, are especially virulent and lethal to larvae and metamorphs. In this paper we describe a novel ranavirus isolate as well as the first recorded occurrence of ranavirus in the southern High Plains of Texas and in associated populations of the spotted chorus frog Pseudacris clarkii. The breeding sites were playas, that is, wetlands that fill via isolated thunderstorms that can occur infrequently; thus, not every playa has water or breeding amphibians annually. We did not detect ranavirus in sympatric anurans, but other reports document ranaviruses in Pseudacris spp. elsewhere. The occurrence of multiple isolates of ranavirus in a number of Pseudacris species suggests that this genus of frogs is highly susceptible to ranaviruses and may experience exceptionally high mortality rates from infection. Thus, the virus may contribute to substantial seasonal population declines and low seasonal recruitment, with negative impacts on populations of breeding adults in successive years.     

Effects of cooling dry cows under heat load conditions on mammary gland enzymatic activity, intake of food and water, and performance during the dry period and after parturition

Effect of evaporative cooling of pregnant dairy cows under heat load conditions during the dry and close-up period, on mammary gland enzymatic activity and intake of food and water, BCS, and milk performance after calving were measured in two consequent experiments. In experiment 1, 18 dry cows held in tie-stalls in a closed aerated barn under heat load conditions were used to measure the effect of evaporative cooling on the respiratory rate and body temperature, individual intake of food and water, enzymes expression level in mammary gland and adipose tissues, and BCS changes until calving. In experiment 2, two groups of 36 dry cows each, held in a commercial loose housing barn, were used to measure the effects of evaporative cooling under heat load conditions on calves' birth weight, colostrum quality and quantity, BCS changes and milk yield during 90 DIM. The non cooled (NC) cows responded to heat load by increasing their respiratory rate and daily water intake, while elevating their rectal temperature by 0.2–0.3 °C as compared with the cooled (C) cows. The external relief of heat load by the C cows in both experiments was expressed in increasing their voluntary DMI during the dry period as compared with the NC group. In experiment 2 the calves' birth weight of C cows was higher, and their colostrum quality and quantity were improved as compared with the NC group. Cooling also improved significantly BCS gain during the last 21 days until parturition, accompanied with higher cell proliferation process (based on enzymes expression at mRNA level) in the mammary gland of the C cows. Consequently, a significant increase in milk production by 5.3%, protein yield by 5.1%, ECM yield by 4.2% and FCM yield by 4.5%, was demonstrated in the C cows during 90 DIM as compared with the NC group.     

Thermoregulation and evaporative water loss in growing African giant rats Cricetomys gambianus

Kalahari Gemsbok National Park, Private Bag X5890, Upington, 8800 Republic of South AfricaWith an increase in mass, weaned giant rat pups Cricetomys gambianus, showed a corresponding decline in mass specific metabolism, conductance and evaporative water loss. The decline in metabolism correlates better with mass than age, while conductance correlates better with age than mass. After 77 days of age the relative importance of dry thermal conductance increased and this is attributed to the testes becoming scrotal, and acting as a thermal window. The final desertion of the nest by young is suggested to coincide with the advent of an efficient thermoregulatory capacity.     

Integrative taxonomy helps to reveal the mask of the genus Gynandropaa (Amphibia: Anura: Dicroglossidae)

Species of the genus Gynandropaa within the family Dicroglossidae are typical spiny frogs whose taxonomic status has long been in doubt. We used integrative methods, involving morphological and molecular analyses, to elucidate the phylogenetic relationships, and to determine identities and the geographic distribution of each valid species. We obtained DNA sequence data of 5 species of Gynandropaa (complete sequences of the mitochondrial NADH dehydrogenase subunit 2 [ND2] gene, and 890 bp of 12S rRNA and 16S rRNA partial sequences) from 37 localities (including the topotypes of 5 described species) and constructed Bayesian and maximum‐likelihood trees to examine the patterns of phylogeography. A total of 28 morphological variables were taken on 624 specimens. Three clades with clear geographic patterns were recognized: clade C (from south‐western Sichuan Province and central Yunnan Province), clade E (western Guizhou Province and eastern to central Yunnan Province) and clade W (western to southern Yunnan Province). Integrating morphological characteristics and distribution information, the clades W, E and C represent Gynandropaa yunnanensis, G. phrynoides and G. sichuanensis, respectively. We draw the following conclusions: (i) the taxon G. phrynoides, formerly evaluated as a junior synonym of G. yunnanensis, is revalidated herein at the rank of species; (ii) G. liui is a junior synonym of G. sichuanensis; and (iii) G. yunnanensis is a valid species while G. bourreti is probably a subspecies of G. yunnanensis, with the distribution range from Vietnam to southern Yunnan Province. This study clears up the taxonomic status of Gynandropaa and provides important information for understanding the evolution and conservation of these spiny frogs.     

Life Histories of Frogs in the Namib Desert

Four anuran taxa inhabit the central Namib: Xenopus laevis, Tomopterna delalandei cryptotis, Phrynomerus annectens and Bufo vertebrate hoeschi. Xenopus is confined to permanent pools in the Kuiseb river canyon. Tomopterna extends further into the Namib, but is restricted to the Kuiseb river bed. The Kuiseb is normally dry, receiving water only briefly (as floods) during the rainy season. These floods are responsible for moving adults and larvae. Phrynomerus and Bufo occur on granite inselbergs. The inselbergs provide shelter mainly in the form of cracks under granite exfoliations. Large runoff surfaces collect the low rainfall (25 mm per year) in depressions in which the frogs breed. Phrynomerus is only active at night; males are aggressive towards one another; oviposition takes place in deep pools and development takes at least eight weeks. Bufo is active during the heat of the day; oviposition takes place in warm shallow pools; development takes about three weeks.     

Effects of temperature and hydric environment on survival of the Panamanian Golden Frog infected with a pathogenic chytrid fungus

Considerable controversy exists concerning whether or not climate changes (particularly global warming) are causing outbreaks of a lethal amphibian pathogen, the chytrid fungus Batrachochytrium dendrobatidis (Longcore, Pessier & D.K. Nichols 1999). In the present study, groups of Panamanian golden frogs (Atelopus zeteki Dunn, 1993), a critically endangered amphibian thought to be nearly extinct in Panama, were exposed to varying dosages of zoospores of Batrachochytrium dendrobatidis, temperatures and hydric environments in order to learn whether this species is susceptible to this pathogen and, if so, how environmental factors affect survival. This pathogen proved to be highly lethal for A. zeteki. Frogs exposed to a dosage of 100 Bd zoospores survived significantly (P < 0.0001) longer than those that had been exposed to 10⁴ or 10⁶ zoospores. Exposed frogs housed at 23 °C survived significantly (P < 0.0001) longer than those that were housed at 17 °C. Exposed frogs held in dry conditions survived significantly longer than those in wet conditions (P < 0.0001). As a laboratory study, these results do not directly test hypotheses about the relation between climate change and the decline of these frogs in the field, but they inform the discussion about how environmental conditions can have an impact on the interaction between a susceptible amphibian and this pathogen. These data do not support the contention that rising global temperatures are necessary to cause the death of amphibians infected with this pathogen because the pathogen was equally lethal at 17 as at 23 °C, and frogs at the warmer temperature lived significantly longer than those at the cooler one.     

Comparison of toe pads of some southern African climbing frogs

The morphology of the toe pads of eight species of Hyperolius (Hyperoliidae), Chiromantis xerampelina, Leptopelis natalensis and Kassina maculata (Rhacophoridae) was examined using a scanning electron microscope. Disc width, margin width and toe pad cell size are variable in Hyperolius, but not directly related to frog size. The rhacophorids were found to have type II mucous pores, contradicting earlier findings. SEM work on toe pads is not taxonomically useful at the species level. We suggest that the circumferal groove may play a role in retaining liquid essential for the adhesion of tree-frog toe pads to smooth surfaces.     

Thermoregulation and Water Balance as Affected by Water and Food Restrictions in Sudanese Desert Goats Fed Good-quality and Poor-quality Diets

Nine desert goats were used in a 3 x 3 Latin square design in which they were subjected to (a) ad libitum water and food (control), (b) ad libitum food and water restricted to about 40% of the control, and (c) ad libitum water and restricted food (same amount as given to group b). Parameters measured were dry matter intake (DMI), water intake, rectal temperature (Tr), respiration rate (RR), water balance and body weight (BW) changes. The acute effects of the above treatments on these parameters were monitored during the dry summer using two types of feed. The ratio of DMI to water intake decreased (p < 0.01) due to water restriction but increased (p < 0.01) with Lucerne hay compared to grass hay. With both feeds, BW decreased (p < 0.01) with water restriction, with a further decrease (p < 0.01) observed with food restriction. The control group showed a higher (p < 0.01) gain with Lucerne hay than grass hay. Tr and RR increased (p < 0.01) from morning to afternoon; Tr decreased due to food restriction during both morning and afternoon with Lucerne hay (p < 0.05) and grass hay (p < 0.05), whereas RR decreased (p < 0.01) with both types of feeds. For all groups of animals, Tr was higher (p < 0.05) with Lucerne hay than with grass hay, this effect being more pronounced (p < 0.01) with the control group. With both feeds, water restriction decreased (p < 0.01) water turnover rate and evaporative losses, with decreased (p < 0.05) faecal losses observed in the water-restricted groups on Lucerne hay but higher (p < 0.05) losses of urine. The tolerance of desert goats to thermal stress and their coping with shortage of water and food depended on their capacity to lose heat through panting and cutenaous evaporation as well as their ability to concentrate urine.     

Do public attitudes affect conservation effort? Using a questionnaire-based survey to assess perceptions,beliefs and superstitions associated with frogs in South Africa

Globally, amphibians are among the least appreciated vertebrates and are often negatively perceived by the general public. Such attitudes are particularly prevalent in South Africa, where fear, superstitions and myths associated with frogs are pervasive in some cultures. These attitudes could have harmful consequences both for the animals concerned and conservation efforts. This study aimed to investigate attitudes to frogs throughout South Africa across multiple age and ethnic groups. We used a multi-language survey in both hard-copy and online versions. Respondents (n = 2 295) comprised both genders across six age groups and five ethnic groups. A functionalist approach using structural equation modelling was used to assess how liking of frogs and cultural beliefs varied with socio-demographic factors. Attitudes varied significantly between groups, with males more likely to like frogs than females and age and level of education also significantly linked to liking. The influence of cultural beliefs and lack of knowledge also directly influenced negative attitudes towards frogs. More than 60% of respondents expressed an interest in learning more about frogs, indicating an opportunity for improving attitudes through educational outreach. The findings of this study can be used to inform current efforts to protect amphibians in South Africa through social interventions.     

Annual Variations in <Emphasis Type="Italic">Leptospira</Emphasis> Seroprevalence among Sows in Southern Vietnam

A serological survey was conducted among sows in the Mekong delta in southern Vietnam in 1999 to investigate variations in leptospiral Seroprevalence over a one-year period. In this region, leptospirosis is endemic and a high leptospiral Seroprevalence has been shown in the pig population. In this study, the serology of six Leptospira serovars was analysed by the microscopic agglutination test for 429 sows at five large-scale state farms sampled during the dry period, the rainy period and the early dry period. The serovars included were L. interrogans serovar (sv) autumnalis strain Akiyama A, L. interrogans sv bratislava strain Jez, L. interrogans sv icterohaemorrhagiae strain Kantorowicz, L. interrogans sv pomona strain Pomona, L. borgpetersenii sv tarassovi strain Perepelitsin, and L. kirschneri sv grippotyphosa strain Duyster. Variations in Seroprevalence over the year were found for sv bratislava and sv icterohaemorrhagiae: the Seroprevalence was higher during the dry period compared with the rainy period (p = 0.07 and p = 0.005, respectively) and the early dry period (p = 0.00006 and p = 0.0006, respectively). It is concluded that in regions where water is constantly abundant and where animals are exposed to the outdoor environment all year round there are highly significant variations in leptospiral Seroprevalence over the year.     

Wild‐Caught and Farm‐Reared Amphibians are Important Reservoirs of Salmonella,A Study in North‐East Thailand

The role of amphibians as Salmonella reservoirs has not been as well studied as in reptiles, where the literature is abundant. Recent outbreaks of salmonellosis associated with exotic pet frogs have occurred in United States. Frog farming and wild frog harvesting have increased the international trade in these species. This necessitates a better understanding of the risk of salmonellosis transmission from amphibians to humans. We explored the presence of Salmonella in amphibians (frogs and toads) in Thailand, where farmed and wild frogs as well as toads are present. These live animals are easily found in the local markets and are used as food. Exportation of frog meat from Thailand is common. During March–June 2014, ninety‐seven frogs were collected from several habitats, including frog farms, urban areas and protected natural areas. The collected amphibians were tested for the presence of Salmonella. The overall prevalence of Salmonella was 69.07% (90.00% in farm animals, 0% in urban area animals and 44.83% in protected area animals). Eight serovars of Salmonella were isolated: subsp. diarizonae ser. 50:k:z, Hvittingfoss, Muenchen, Newport, Stanley, Thompson, Panama and Wandsworth. Six of the identified serovars, Hvittingfoss, Newport, Panama, Stanley, Thompson and Wandsworth, have been detected in humans in Thailand. According to our results, amphibians are reservoirs of Salmonella and can be a public health concern when used as a source of protein for humans.     

Introduction to an evaluation of the protection status of South Africa's vertebrates

During the Zoological Society of Southern Africa's 1994 Symposium in Pietermaritzburg, a theme session was convened to evaluate the protection status of selected groups of South African vertebrates (viz. freshwater fish, frogs, tortoises and terrapins, snakes, birds, and various mammal orders). The research papers presented during that session are reported in this number of the South African Journal of Zoology. The rationale behind the research, and the data and methods used, are described in this introductory paper. South Africa's national and international contractual obligations to conserve its biodiversity, and the urgent need for a national conservation strategy and national conservation information networks and databases, are also discussed.     

A preliminary biochemical genetic survey of four South African painted reed frog (Hyperolius marmoratus) populations

Allozyme electrophoresis was used to evaluate genetic variability in painted reed frog (Hyperolius marmoratus) populations from the Northern Province and the Eastern Cape. Sixteen protein-encoding loci were resolved, of which seven displayed allelic polymorphism. Average heterozygosity (H) values in two permanent H. m. taeniatus populations from the Northern Province (7.9% and 6.3%) did not differ substantially from each other nor from the geographically distant Eastern Cape H. m. verrucosus (9.1%). An isolated Northern Province H. m. taeniatus population displayed more polymorphism than any other group with H=14.1%, which can probably be attributed to the periodic influx of reed frogs following dry periods. Genetic distances and gene diversity (F_ST) values conformed with expected values for conspecific populations. The results attained concur with the hypothesis of increased genetic heterogeneity among populations of small and relatively sedentary animals     

Temporal niche overlap among insectivorous small mammals

Being active in the same environment at different times exposes animals to the effects of very different environmental factors, both biotic and abiotic. In the present study, we used live traps equipped with timing devices to evaluate the potential role of biotic factors (competition and food abundance) on overall overlap in the temporal niche axis of 4 insectivorous small mammals in high‐elevation grassland fields (‘campos de altitude’) of southern Brazil. Based on resources availability (invertebrates), data on animal captures were pooled in 2 seasons: ‘scarcity’ (June 2001–September 2001) and ‘abundance’ (November 2001–May 2002) seasons. We tested for non‐random structure in temporal niche overlap among the species in each season. These species were the rodents Oxymycterus nasutus (Waterhouse, 1837), Deltamys sp., Akodon azarae (Fischer, 1829), and the marsupial Monodelphis brevicaudis Olfers, 1818. The studied community was mainly diurnal with crepuscular peaks. Simulations using the Pianka index of niche overlap indicated that the empirical assemblage‐wide overlap was not significantly different from randomly generated patterns in the abundance season but significantly greater than expected by chance alone in the scarcity season. All the species showed an increase in temporal niche breadth during the abundance season, which appears to be related to longer daylength and high nocturnal temperatures. Patterns on both temporal niche overlap and temporal niche breadth were the opposite to those that we were expecting in the case of diel activity patterns determined by competition for dietary resources. Therefore, we conclude that competition did not seem to be preponderant for determining patterns of temporal niche overlap by the studied community.     

Electron Microscopy of Bactericidal Effects Produced by the Alternative Complement Pathway of Channel Catfish

Abstract

The activation of the alternative complement pathway (ACP) was investigated by incubating serum of channel catfish Ictalurus punctatus with three gram-negative bacteria. Bactericidal activity and ultrastructural damage were not apparent when cells were incubated with serum that had been treated to eliminate complement activity. Proteins of the ACP were responsible for damaging susceptible Escherichia coli and Pseudomonas fuorescens, whereas there was no effect on Aeromonas salmonicida, which was apparently protected by an A-layer. Scanning electron micrographs revealed damaged cells, and transmission electron micrographs showed circular lesions oriented perpendicularly to the cell membrane. These lesions resemble those resulting from ACP activation in sera from frogs, sharks, trout, lizards and mammals. The existence of membrane attack complexes (MACs) in channel catfish, which are similar to MACs seen in other animals, emphasizes the importance of the ACP in host defense against bacterial infections.     

The effect of salt and bentonite supplementation on feed and water intake, faecal characteristics and urine output in sheep

The effects of the addition of salt (sodium chloride) and sodium bentonite to hay-based pelleted rations on feed and water intake, digestibility, the output of urine and faeces, and faecal consistency were evaluated under conditions resembling those used for the shipment of live sheep. The addition of salt to the diet had no effect on dry matter intake but increased water intake relative to controls (P<0.01), with commensurate increases in urinary output of more than 1 litre/sheep/day. The diet with bentonite plus salt resulted in a higher dry matter intake than controls (P<0.01). The addition of bentonite increased the faecal dry matter percentage (P<0.05). The effects of the additives on faecal water evaporative loss and hardness were not significant. A large variation (52.1-62.6%) between sheep in dry matter digestibility of feeds was not affected by treatment and this requires further investigation. It is recommended that salt not be added to diets used for live sheep shipments.     

Sampling ryegrass to assess the risk of annual ryegrass toxicity

SUMMARY Most stock losses caused by annual ryegrass toxicity occur because stockowners unknowingly allow their stock to graze annual ryegrass (Lollum rigidum) Infected with the bacterium Clavlbacter toxicus. To help stockowners avoid losses we have developed criteria for a testing service to determine the risk of poisoning before the pasture is grazed. Low, medium and high risk categories were selected using samples of dry, mature ryegrass seedheads collected by stockowners from untreated, Infected pastures In South Australia. The proportion of toxic paddocks in each risk category over all the seasons tested was 11%;, 32%; and 76%;, respectively, and these accounted for 7%;, 14%; and 79%; of total stock losses. The proportion of paddocks in which stock were poisoned did not vary significantly between years, was not affected by variation in sample weight, and did not vary between South Australia and Western Australia.     

Seroprevalence of Mycoplasma hyopneumoniae in pigs in subtropical southern China

Enzootic pneumonia caused by Mycoplasma hyopneumoniae is a severe disease of pigs, causing significant economic losses to the pig industry worldwide, including the tropical and subtropical regions. In order to obtain the baseline prevalence of M. hyopneumoniae in pigs from intensive farms in southern China, double-sandwich enzyme-linked immunosorbent assay (ELISA) was used to detect M. hyoneumoniae antibodies in 460 pig serum samples collected from 12 administrative cities in China’s southern Guangdong province. According to the proportions of the infected animals, among the 12 intensive farms, only two of them showed no infection of M. hyoneumoniae and the seroprevalence ranged from 0% to 90%, with an averaged prevalence of 45.7%. The highest prevalence was found in breeding boars (68.8%), followed by sows (54.5%). These data showed that the infection of pigs with M. hyopneumoniae is severe, and boars might be more important carriers and transfers of M. hyoneumoniae than sows. Integrated strategies and measures should be taken to control the infection of pigs with M. hyopneumoniae in southern China.