Memphis, TN, United States
Memphis, TN, United States

Time filter

Source Type

Germano J.M.,Memphis Zoo | Arregui L.,Memphis Zoo | Arregui L.,Autonomous University of Madrid | Kouba A.J.,Memphis Zoo
Aquaculture | Year: 2013

The importance of developing assisted reproductive technologies (ART) for captive assurance colonies of threatened amphibians is increasing as ex situ management of amphibians has been challenged with low reproductive outputs for some species. One hurdle to developing ART in amphibians is the short-term storage of gametes for in vitro fertilization. This study tested the application of two common aquaculture techniques, aeration or the addition of antibacterial solutions, to spermic urine to determine if this would improve the longevity and quality of non-invasively collected sperm samples using hormone therapy. Spermic urine samples were collected non-invasively from Fowler's toads (Bufo fowleri) and either left alone, aerated for 30. min a day, or treated with penicillin-streptomycin. All samples were kept refrigerated at 4. °C. Sperm motility declined within each treatment group over time (P<0.01); however, aerated samples retained significantly greater motility (70%) during the first 24. h after collection than samples in both the control (57%) and antibacterial group (51%). The addition of penicillin-streptomycin solution to spermic urine had a negative effect on viability; with significantly fewer sperm still alive 2-4. days post collection (P≤0.032). Sperm viability was highly correlated with motility on all days and with forward progression 1-4. days post collection (P≤0.002). Our results show that aerating amphibian spermic urine samples may provide a simple and low-cost method to improve sperm storage that could be used for in vitro fertilization and ex situ management of threatened amphibians. Antibiotics appeared to have a negative effect on sperm viability, suggesting that further research on bacterial contamination and antibiotic doses is necessary. © 2013 Elsevier B.V.

Kouba A.J.,Memphis Zoo | Lloyd R.E.,University of Portsmouth | Houck M.L.,Institute for Conservation Research | Silla A.J.,University of Wollongong | And 10 more authors.
Biological Conservation | Year: 2013

How to conserve our planet's rapidly disappearing biodiversity is one of the greatest challenges of our generation. Among terrestrial vertebrate taxa, amphibians are most at risk with 41% of all known species experiencing population declines and one-third threatened with extinction. Although many institutions have responded by establishing captive assurance colonies for several critically endangered amphibians, the resources provided by these conservation organizations will not be enough to save all species 'at risk' without a multi-pronged approach. Around the world, zoos, aquariums, governments, and conservation NGOs are beginning to establish amphibian gene banks to conserve, in perpetuity, the remaining extant genetic diversity for many of these critically endangered species. A suite of biomaterials has been targeted for cryoconservation including blood, cell cultures, tissues, spermatozoa, eggs, and embryos. Several international workshops on amphibian gene banking and assisted reproductive technologies have been held between 2010 and 2012, bringing together leading experts in the fields of amphibian ecology, physiology, and cryobiology to synthesize emerging trends for biobanking amphibian genetic resources, provide opportunities for collaboration, and discuss future research directions. The following review paper and summary will provide a synopsis of these international workshops, in particular the hopes, realities, and current challenges inherent to this applied research field. © 2013 Elsevier Ltd.

Kouba A.J.,Memphis Zoo | Kouba A.J.,Mississippi State University | delBarco-Trillo J.,University of Memphis | delBarco-Trillo J.,CSIC - National Museum of Natural Sciences | And 3 more authors.
Reproductive Biology and Endocrinology | Year: 2012

Background: Captive breeding programs for endangered amphibian species often utilize exogenous hormones for species that are difficult to breed. The purpose of our study was to compare the efficacy of two different hormones at various concentrations on sperm production, quantity and quality over time in order to optimize assisted breeding.Methods: Male American toads (Anaxyrus americanus) were divided into three separate treatment groups, with animals in each group rotated through different concentrations of luteinizing hormone releasing hormone analog (LHRH; 0.1, 1.0, 4.0 and 32 micrograms/toad), human chorionic gonadotropin (hCG; 50, 100, 200, and 300 IU), or the control over 24 hours. We evaluated the number of males that respond by producing spermic urine, the sperm concentration, percent motility, and quality of forward progression. We also evaluated the effects of hCG and LHRH on reproductive behavior as assessed by amplexus. Data were analyzed using the Generalized Estimating Equations incorporating repeated measures over time and including the main effects of treatment and time, and the treatment by time interaction.Results: The hormone hCG was significantly more effective at stimulating spermiation in male Anaxyrus americanus than LHRH and showed a dose-dependent response in the number of animals producing sperm. At the most effective hCG dose (300 IU), 100% of the male toads produced sperm, compared to only 35% for the best LHRH dose tested (4.0 micrograms). In addition to having a greater number of responders (P < 0.05), the 300 IU hCG treatment group had a much higher average sperm concentration (P < 0.05) than the treatment group receiving 4.0 micrograms LHRH. In contrast, these two treatments did not result in significant differences in sperm motility or quality of forward progressive motility. However, more males went into amplexus when treated with LHRH vs. hCG (90% vs. 75%) by nine hours post-administration.Conclusion: There is a clear dichotomy between the two hormones' physiological responses on gamete production and stimulation of amplexus. Understanding how these two hormones influence physiology and reproductive behaviors in amphibians will have direct bearing on establishing similar breeding protocols for endangered species. © 2012 Kouba et al.; licensee BioMed Central Ltd.

PubMed | Memphis Zoo, University of Washington, University of Alaska Fairbanks and National Oceanic and Atmospheric Administration
Type: Journal Article | Journal: Environmental science & technology | Year: 2016

The use of sentinel species for population and ecosystem health assessments has been advocated as part of a One Health perspective. The Arctic is experiencing rapid change, including climate and environmental shifts, as well as increased resource development, which will alter exposure of biota to environmental agents of disease. Arctic canid species have wide geographic ranges and feeding ecologies and are often exposed to high concentrations of both terrestrial and marine-based contaminants. The domestic dog (Canis lupus familiaris) has been used in biomedical research for a number of years and has been advocated as a sentinel for human health due to its proximity to humans and, in some instances, similar diet. Exploiting the potential of molecular tools for describing the toxicogenomics of Arctic canids is critical for their development as biomedical models as well as environmental sentinels. Here, we present three approaches analyzing toxicogenomics of Arctic contaminants in both domestic and free-ranging canids (Arctic fox, Vulpes lagopus). We describe a number of confounding variables that must be addressed when conducting toxicogenomics studies in canid and other mammalian models. The ability for canids to act as models for Arctic molecular toxicology research is unique and significant for advancing our understanding and expanding the tool box for assessing the changing landscape of environmental agents of disease in the Arctic.

De Aquino Ribas A.C.,Memphis Zoo | Brescovit A.D.,Pace Law School | Raizer J.,Federal University of Grande Dourados
Journal of Arachnology | Year: 2011

The presence of buds, flowers, and fruits increases structural complexity in plants, but can also attract potential prey for predators, thus determining faunistic composition. To understand how a spider assemblage living in the shrub Byrsonima intermedia (Malpighiaceae) varies with habitat structure in terms of reproductive elements and height of plant, we collected spider specimens and measured bud, flower, fruit, and leaf masses of 44 plants, as well as their height. Spider family composition was found to depend on habitat structure, following a pattern of family turnover occurring along gradients of reproductive plant elements and height, regardless of plant biomass. Theridiidae occurred in samples with the major proportions of buds and flowers, while Oxyopidae occurred only in samples with major proportions of fruits. Multiple linear regression revealed the strong relation between the composition in reproductive plant elements and the composition in families of spiders and a relation between shrub height and spider family composition. These results help us to understand the temporal dynamics between structural complexity of vegetation and spider assemblages, because during plant phenology the proportions of reproductive elements are also varying. © 2011 The American Arachnological Society.

Clulow J.,University of Newcastle | Trudeau V.L.,University of Ottawa | Kouba A.J.,Memphis Zoo
Advances in Experimental Medicine and Biology | Year: 2014

Each amphibian species is evolutionarily distinct, having developed highly specialized and diverse reproductive strategies in both terrestrial and aquatic environments. These unique reproductive patterns and mechanisms, key to species propagation, have only been explored in a limited number of laboratory models. Although the development of applied reproductive technologies for amphibians has proven useful for a few threatened species, the real benefit of this technology has been new insights into the reproductive adaptations, behavior, endocrinology, and physiological mechanisms that have evolved over millions of years. As the basic fundamental database on amphibian reproductive physiology has grown, so has the applied benefit for species conservation. In particular, technologies such as non-invasive fecal and urinary hormone assays, hormone treatments for induced breeding or gamete collection, in vitro fertilization, and the ability to establish genome resource banks have all played important roles in monitoring or managing small populations of captive species. Amphibians have the ability to produce a large excess of germplasm (up to 10,000 ovulated eggs in a single reproductive event) that if not collected and preserved, would represent a wasted valuable resource. We discuss the current state of knowledge in assisted reproductive technologies for amphibians and why their extinction crisis means these available tools can no longer be implemented as small-scale, last-ditch efforts. The reproductive technologies must be established early as a key component of large-scale species recovery. © Springer Science+Business Media New York 2014.

Swaisgood R.R.,San Diego Zoos Institute for Conservation Research | Wei F.,CAS Institute of Zoology | Mcshea W.J.,Conservation and Research Center | Wildt D.E.,Conservation and Research Center | And 4 more authors.
Integrative Zoology | Year: 2011

The giant panda (Ailuropoda melanoleuca David, 1869) is an iconic species for global conservation, yet field research has only recently advanced to the point where adaptive management is possible Here, we review recent developments in giant panda conservation science and propose a strategic plan for moving panda conservation forward. Because of scientific, funding, political, and logistical hurdles, few endangered species management programs have embraced adaptive management, wherein management decisions are shaped iteratively by targeted scientific research. Specific threats, such as habitat destruction, anthropogenic disturbance and fragmented nonviable populations, need to be addressed simultaneously by researchers, managers and policy-makers working in concert to understand and overcome these obstacles to species recovery. With the backing of the Chinese Government and the conservation community, the giant panda can become a high-profile test species for this much touted, but rarely implemented, approach to conservation management. © 2011 ISZS, Blackwell Publishing and IOZ/CAS.

Reichling S.B.,Memphis Zoo | Baker C.,Memphis Zoo | Swatzell C.,Pace Law School
Journal of Arachnology | Year: 2011

A large population of Sphodros rufipes (Latreille 1829) was discovered in a municipal park in Memphis, Tennessee. We examined potential stem diameter preference, frequency of web attachment to available tree species and the spatial distribution patterns of spiders and potential attachment structures. A wide range of structure diameters were utilized for web attachment. The association of pursewebs to tree taxa was independent of the frequency of tree taxa occurrence. The spacing of vegetation stems and trunks was approximately random, but spiders exhibited a nonrandom, aggregated distribution, which was more pronounced in subadults than adults. The factors influencing S. rufipes to occur in aggregations cannot be explained by the spatial proximity of potential attachment structures in the forest. © 2011 The American Arachnological Society.

Swaisgood R.R.,San Diego Zoos Institute for Conservation Research | Wei F.,CAS Institute of Zoology | Wildt D.E.,Conservation and Research Center | Kouba A.J.,Memphis Zoo | And 2 more authors.
Biology Letters | Year: 2010

The giant panda is a conservation icon, but science has been slow to take up its cause in earnest. In the past decade, researchers have been making up for lost time, as reflected in the flurry of activity reported at the symposium Conservation Science for Giant Pandas and Their Habitat at the 2009 International Congress for Conservation Biology (ICCB) in Beijing. In reports addressing topics ranging from spatial ecology to molecular censusing, from habitat recovery in newly established reserves to earthquake-induced habitat loss, from new insights into factors limiting carrying capacity to the uncertain effects of climate change, this symposium displayed the vibrant and blossoming application of science to giant panda conservation. Collectively, we find that we have come a long way, but we also reach an all-too-familiar conclusion: the more we know, the more challenges are revealed. While many earlier findings are supported, many of our assumptions are debatable. Here we discuss recent advancements in conservation science for giant pandas and suggest that the way forward is more direct application of emerging science to management and policy. © 2010 The Royal Society.

PubMed | Memphis Zoo, Native Aquatic Species Restoration Facility and Mississippi State University
Type: Journal Article | Journal: Theriogenology | Year: 2015

Declines of the southern Rocky Mountain population of boreal toad (Anaxyrus boreas boreas) have led to the establishment of a captive assurance population and reintroduction program, in an attempt to preserve and propagate this geographically isolated population. One of the unique adaptations of this species is its ability to survive in cold environments by undergoing long periods of hibernation. In captivity, hibernation can be avoided altogether, decreasing morbidity caused by compromised immune systems. However, it is not entirely clear how essential hibernation is to reproductive success. In this study, the effects of hibernation versus nonhibernation, and exogenous hormones on oviposition, were examined in boreal toad females in the absence of males. In the summers of 2011 and 2012, 20 females housed at Mississippi State University were treated with a double priming dose of hCG and various ovulatory doses of hCG and LH-releasing hormone analog but denied hibernation. Exogenous hormones, in the absence of hibernation, could not induce oviposition over two breeding seasons (2011-2012). In contrast, during the summer of 2012 and 2013, 17 of 22 females (77%) housed at the Native Aquatic Species Restoration Facility (Alamosa, CO, USA) oviposited after they were treated with two priming doses of hCG (3.7 IU/g each) and a single ovulation dose of hCG (13.5 IU/g) and LH-releasing hormone analog (0.4g/g) after hibernation. There was a significant difference in oviposition between females that were hibernated and received hormones (2012, P<0.05 and 2013, P<0.01) compared to hibernated control females. In 2013, 12 of 16 remaining Mississippi State University females from the same group used in 2011 and 2012 were hibernated for 1, 3, and 6months, respectively and then treated with the same hormone regimen administered to females at the Native Aquatic Species Restoration Facility. Together, hibernation and hormone treatments significantly increased oviposition (P<0.05), with 33% of females ovipositing. These results suggest that (1) hibernation is a key factor influencing oviposition that cannot be exclusively circumvented by exogenous hormones; (2) females do not require the presence of a male to oviposit after hormone treatments; and (3) longer hibernation periods are not beneficial for oviposition. The hormonal induction of oviposition in the absence of males and shorter hibernation periods could have important captive management implications for the boreal toad. Furthermore, the production of viable offspring by IVF where natural mating is limited could become an important tool for genetic management of this boreal toad captive population.

Loading Memphis Zoo collaborators
Loading Memphis Zoo collaborators