A cross-species comparison of escape from X inactivation in Eutheria: implications for evolution of X chromosome inactivation

Sex chromosome dosage compensation in both eutherian and marsupial mammals is achieved by X chromosome inactivation (XCI)—transcriptional repression that silences one of the two X chromosomes in the somatic cells of females. We recently used RNA fluorescent in situ hybridization (FISH) to show, in individual nuclei, that marsupial X inactivation (in the absence of XIST) occurs on a gene-by-gene basis, and that escape from inactivation is stochastic and independent of gene location. In the absence of similar data from fibroblast cell lines of eutherian representatives, a meaningful comparison is lacking. We therefore used RNA-FISH to examine XCI in fibroblast cell lines obtained from three distantly related eutherian model species: African savannah elephant (Loxodonta africana), mouse (Mus musculus) and human (Homo sapiens). We show that, unlike the orthologous marsupial X, inactivation of the X conserved region (XCR) in eutherians generally is complete. Two-colour RNA-FISH on female human, mouse and elephant interphase nuclei showed that XCR loci have monoallelic expression in almost all nuclei. However, we found that many loci located in the evolutionarily distinct recently added region (XAR) displayed reproducible locus-specific frequencies of nuclei with either one or two active X alleles. We propose that marsupial XCI retains features of an ancient incomplete silencing mechanism that was augmented by the evolution of the XIST gene that progressively stabilized the eutherian XCR. In contrast, the recently added region of the eutherian X displays an incomplete inactivation profile similar to that observed on the evolutionarily distinct marsupial X and the independently evolved monotreme X chromosomes

Captive reptile mortality rates in the home and implications for the wildlife trade

The trade in wildlife and keeping of exotic pets is subject to varying levels of national and international regulation and is a topic often attracting controversy. Reptiles are popular exotic pets and comprise a substantial component of the live animal trade. High mortality of traded animals raises welfare concerns, and also has implications for conservation if collection from the wild is required to meet demand. Mortality of reptiles can occur at any stage of the trade chain from collector to consumer. However, there is limited information on mortality rates of reptiles across trade chains, particularly amongst final consumers in the home. We investigated mortality rates of reptiles amongst consumers using a specialised technique for asking sensitive questions, additive Randomised Response Technique (aRRT), as well as direct questioning (DQ). Overall, 3.6% of snakes, chelonians and lizards died within one year of acquisition. Boas and pythons had the lowest reported mortality rates of 1.9% and chameleons had the highest at 28.2%. More than 97% of snakes, 87% of lizards and 69% of chelonians acquired by respondents over five years were reported to be captive bred and results suggest that mortality rates may be lowest for captive bred individuals. Estimates of mortality from aRRT and DQ did not differ significantly which is in line with our findings that respondents did not find questions about reptile mortality to be sensitive. This research suggests that captive reptile mortality in the home is rather low, and identifies those taxa where further effort could be made to reduce mortality rate

Supplying the wildlife trade as a livelihood strategy in a biodiversity hotspot

Much of the global wildlife trade is sourced from biodiversity-rich developing countries. These often have high levels of poverty and habitat loss, particularly in rural areas where many depend on natural resources. However, wildlife collection may incentivize local people to conserve habitats that support their livelihoods. Here we examined the contribution of the commercial collection of live animals to rural livelihoods in Madagascar, one of the world’s most important biodiversity hotspots. Using questionnaires, we investigated the prevalence, profitability relative to other livelihood activities, and local importance of the trade, and its capacity to provide incentives for conservation. Thirteen percent of households were engaged in live animal collection in the study area (~5% trapped reptiles and amphibians and the remainder trapped invertebrates). This formed part of a diverse livelihood strategy, and was more profitable than other activities (in terms of returns per unit of effort), with median earnings of ~US$100 per season (~25% of Gross National Income per year). However, trapping was part-time, usually undertaken by poorer members of the community, and often perceived as opportunistic, risky, and financially unreliable. Further, trappers and nontrappers held similar perceptions regarding conservation, suggesting wildlife trade currently does not incentivize enhanced stewardship of traded species and their habitats. Our study brings together a range of methodologies to present the most comprehensive insights into livelihoods and conservation in poor rural communities involved in the commercial collection of live animals to supply international trade. This improved understanding of the wider socioeconomic dimensions of wildlife trade can inform policy and management interventions for both the threats and opportunities associated with global trade in biodiversity both in Madagascar and more generally

Chagas Disease in a Domestic Transmission Cycle in Southern Texas, USA

After three dogs died from acute Chagas cardiomyopathy at one location, an investigation was conducted of the home, garage, and grounds of the owner. A serologic study was conducted on stray dogs, and an ecologic niche model was developed to predict areas where the vector Trypanosoma gerstaeckeri might be expected

Wildlife supply chains in Madagascar from local collection to global export

International trade in wildlife is a complex multi-billion dollar industry. To supply it, many animals are extracted from the wild, sourced from biodiversity-rich, developing countries. Whilst the trade has far-reaching implications for wildlife protection, there is limited information regarding the socio-economic implications in supply countries. Consequently, a better understanding of the costs and benefits of wildlife supply chains, for both livelihoods and conservation, is required to enhance wildlife trade management and inform its regulation. Using Madagascar as a case study, we used value chain analysis to explore the operation of legal wildlife trade on a national scale; we estimate the number of actors involved, the scale, value and profit distribution along the chain, and explore management options. We find that the supply of wildlife provided economic benefits to a number of actors, from local collectors, to intermediaries, exporters and national authorities. CITES-listed reptiles and amphibians comprised a substantial proportion of the quantity and value of live animal exports with a total minimum export value of 230,795USD per year. Sales prices of reptiles and amphibians increased over 100-fold between local collectors and exporters, with exporters capturing ~92% of final export price (or 57% when their costs are deducted). However, exporters shouldered the largest costs and financial risks. Local collectors obtained ~1.4% of the final sales price, and opportunities for poverty alleviation and incentives for sustainable management from the trade appear to be limited. Promoting collective management of species harvests at the local level may enhance conservation and livelihood benefits. However, this approach requires consideration of property rights and land-tenure systems. The complex and informal nature of some wildlife supply chains make the design and implementation of policy instruments aimed at enhancing conservation and livelihoods challenging. Nevertheless, value chain analysis provides a mechanism by which management actions can be more precisely targeted

Identifying species likely threatened by international trade on the IUCN Red List can inform CITES trade measures

Overexploitation is a major threat to biodiversity and international trade in many species is regulated through the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). However, there is no established method to systematically determine which species are most at risk from international trade to inform potential trade measures under CITES. Here, we develop a mechanism using the International Union for Conservation of Nature’s Red List of Threatened Species to identify species that are likely to be threatened by international trade. Of 2,211 such species, CITES includes 59% (1,307 species), leaving two-fifths overlooked and in potential need of international trade regulation. Our results can inform deliberations on potential proposals to revise trade measures for species at CITES Conference of the Parties meetings. We also show that, for taxa with biological resource use documented as a threat, the number of species threatened by local and national use is four times greater than species likely threatened by international trade. To effectively address the overexploitation of species, interventions focused on achieving sustainability in international trade need to be complemented by commensurate measures to ensure that local and national use and trade of wildlife is well-regulated and sustainable

Diversity and prevalence of zoonotic infections at the animal-human interface of primate trafficking in Peru

Wildlife trafficking creates favorable scenarios for intra- and inter-specific interactions that can lead to parasite spread and disease emergence. Among the fauna affected by this activity, primates are relevant due to their potential to acquire and share zoonoses - infections caused by parasites that can spread between humans and other animals. Though it is known that most primate parasites can affect multiple hosts and that many are zoonotic, comparative studies across different contexts for animal-human interactions are scarce. We conducted a multi-parasite screening targeting the detection of zoonotic infections in wild-caught monkeys in nine Peruvian cities across three contexts: captivity (zoos and rescue centers, n = 187); pet (households, n = 69); and trade (trafficked or recently confiscated, n = 132). We detected 32 parasite taxa including mycobacteria, simian foamyvirus, bacteria, helminths, and protozoa. Monkeys in the trade context had the highest prevalence of hemoparasites (including Plasmodium malariae/brasilianum, Trypanosoma cruzi, and microfilaria) and enteric helminths and protozoa were less common in pet monkeys. However, parasite communities showed overall low variation between the three contexts. Parasite richness (PR) was best explained by host genus and the city where the animal was sampled. Squirrel (genus Saimiri) and wooly (genus Lagothrix) monkeys had the highest PR, which was ~2.2 times the PR found in tufted capuchins (genus Sapajus) and tamarins (genus Saguinus/Leontocebus) in a multivariable model adjusted for context, sex, and age. Our findings illustrate that the threats of wildlife trafficking to One Health encompass exposure to multiple zoonotic parasites well-known to cause disease in humans, monkeys, and other species. We demonstrate these threats continue beyond the markets where wildlife is initially sold; monkeys trafficked for the pet market remain a reservoir for and contribute to the translocation of zoonotic parasites to households and other captive facilities where contact with humans is frequent. Our results have practical applications for the healthcare of rescued monkeys and call for urgent action against wildlife trafficking and ownership of monkeys as pets

A Context-Specific Role for Retinoblastoma Protein-Dependent Negative Growth Control in Suppressing Mammary Tumorigenesis

The ability to respond to anti-growth signals is critical to maintain tissue homeostasis and loss of this negative growth control safeguard is considered a hallmark of cancer. Negative growth regulation generally occurs during the G0/G1 phase of the cell cycle, yet the redundancy and complexity among components of this regulatory network has made it difficult to discern how negative growth cues protect cells from aberrant proliferation.The retinoblastoma protein (pRB) acts as the final barrier to prevent cells from entering into the cell cycle. By introducing subtle changes in the endogenous mouse Rb1 gene (Rb1(ΔL)), we have previously shown that interactions at the LXCXE binding cleft are necessary for the proper response to anti-growth signals such as DNA damage and TGF-β, with minimal effects on overall development. This disrupts the balance of pro- and anti-growth signals in mammary epithelium of Rb1(ΔL/ΔL) mice. Here we show that Rb1(ΔL/ΔL) mice are more prone to mammary tumors in the Wap-p53(R172H) transgenic background indicating that negative growth regulation is important for tumor suppression in these mice. In contrast, the same defect in anti-growth control has no impact on Neu-induced mammary tumorigenesis.Our work demonstrates that negative growth control by pRB acts as a crucial barrier against oncogenic transformation. Strikingly, our data also reveals that this tumor suppressive effect is context-dependent