Gastrointestinal parasite assemblages from the wild rodent capybara (Hydrochoerus hydrochaeris) inhabiting a natural protected area from Argentina.

Knowledge about parasitic diseases of wildlife will help us to understand the dynamics of parasites and their effects on host populations. The capybara (Hydrochoerus hydrochaeris) is the largest living rodent in the world, and its distribution is associated with the presence of tropical and subtropical wetlands in South America. The Los Padres Lake Integral Reserve (LPLIR) is an important conservation zone in the pampean region of Argentina. One of the emblematic species found within the reserve is the capybara. The objective of this study was to determine the gastrointestinal parasites present in wild capybaras of the LPLIR and to compare different coprological methodologies. Free-ranging capybara fresh feces from 57 individuals were randomly collected from the area of LPLIR in the summer of 2022. Three different techniques were applied: spontaneous sedimentation technique (SS), INTA modified McMaster technique (MM), and Mini-FLOTAC (MF) technique. Fifty-six samples from all samples analysed (56/57, 98%) were found to be positive for gastrointestinal parasites. Two species of Strongylida, Protozoophaga obesa, Echinocoleus hydrochaeris, one unidentified nematode, one unidentified spirurid, and at least two morphotypes of Eimeria spp. oocysts were recorded. There were found significant differences in the proportion of positive samples and in richness by technique, but no significant differences were found in parasite counting. In conclusion, the choice of methodology depends on the specific objectives of the study. This is the first parasitological study of capybaras from the LPLIR and represents an exploration of parasite communities present in these wild rodents at their southernmost distribution.

Phylogenetic Inferences Based on Distinct Molecular Markers Confirm a Novel Babesia Species (Babesia goianiaensis nov. sp.) in Capybaras (Hydrochoerus hydrochaeris) and Associated Ticks.

Piroplasmids (order Piroplasmida) are a diverse group of tick-borne protozoa that may cause disease in animals and occasionally in humans. Novel Piroplasmida clades and species have been found in wild animals from Brazil based on the phylogenetic assessment of near-complete 18S rRNA, mitochondrial and heat-shock protein genes. For instance, a putative novel Babesia species has been detected in capybaras and Amblyomma ticks in three Brazilian states. The present work aimed to describe, using phylogenetic assessments based on distinct molecular markers, this novel Babesia species in capybaras and associated ticks (Amblyomma sculptum and Amblyomma dubitatum) sampled in Goiânia city, Goiás state, midwestern Brazil. While the phylogenetic analysis based on both near-complete 18S rRNA and hsp-70 genes positioned the sequences obtained from capybara blood samples into a new clade sister to the Babesia sensu stricto clade, the phylogenetic inference based on the COX-3 amino acid positioned the obtained sequences from capybara blood samples and A. sculptum ticks also into a clade sister to the Theileria sensu stricto clade, highlighting the inappropriateness of this marker inferring evolutionary relationships among piroplasmids. Pairwise distance analysis demonstrated that the divergence rates between the 18S rRNA sequences detected in capybaras and other Piroplasmida already described were very high and ranged from 9.4 to 12.9%. Genotype analysis based on the near-full 18S rRNA sequences of the Piroplasmida detected in capybaras and associated ticks demonstrated the occurrence of high genotype diversity at an intra-species level. In conclusion, phylogenetic analyses based on distinct molecular markers supported the description of Babesia goianiaensis nov. sp. in capybaras and associated Amblyomma ticks. Additionally, a novel phylogenetic clade, apart from the previously described ones, was described in the present study and contributed to untangling the complex evolutionary history of the Piroplasmida.

Capybara Oil Improves Renal Pathophysiology and Inflammation in Obese Mice.

Obesity is an inflammatory disease associated with secondary diseases such as kidney disease, which can cause lipotoxicity, inflammation and loss of organ function. Polyunsaturated fatty acids act in the production of lipid mediators and have anti-inflammatory characteristics. In this work, the objective was to evaluate renal histopathology in obese mice and the effects of treatment with capybara oil (CO) (5000 mg/kg/day for 4 weeks). Parameters such as body mass, lipid profile, systolic blood pressure, urinary creatinine and protein excretion, structure and ultrastructure of the renal cortex, fibrosis, tissue inflammation and oxidative stress were analyzed. CO treatment in obese mice showed improvement in the lipid profile and reduction in systolic blood pressure levels, in addition to beneficial remodeling of the renal cortex. Our data demonstrated that CO decreased inflammation, oxidative stress and renal fibrosis, as evidenced by quantifying the expression of TNF-α, IL-10, CAT, SOD, α-SMA and TGF-ß. Although treatment with CO did not show improvement in renal function, ultrastructural analysis showed that the treatment was effective in restoring podocytes and pedicels, with restructuring of the glomerular filtration barrier. These results demonstrate, for the first time, that treatment with CO is effective in reducing kidney damage, being considered a promising treatment for obesity.

Glycoside hydrolase subfamily GH5_57 features a highly redesigned catalytic interface to process complex hetero-ß-mannans.

Glycoside hydrolase family 5 (GH5) harbors diverse substrate specificities and modes of action, exhibiting notable molecular adaptations to cope with the stereochemical complexity imposed by glycosides and carbohydrates such as cellulose, xyloglucan, mixed-linkage ß-glucan, laminarin, (hetero)xylan, (hetero)mannan, galactan, chitosan, N-glycan, rutin and hesperidin. GH5 has been divided into subfamilies, many with higher functional specificity, several of which have not been characterized to date and some that have yet to be discovered with the exploration of sequence/taxonomic diversity. In this work, the current GH5 subfamily inventory is expanded with the discovery of the GH5_57 subfamily by describing an endo-ß-mannanase (CapGH5_57) from an uncultured Bacteroidales bacterium recovered from the capybara gut microbiota. Biochemical characterization showed that CapGH5_57 is active on glucomannan, releasing oligosaccharides with a degree of polymerization from 2 to 6, indicating it to be an endo-ß-mannanase. The crystal structure, which was solved using single-wavelength anomalous diffraction, revealed a massively redesigned catalytic interface compared with GH5 mannanases. The typical aromatic platforms and the characteristic α-helix-containing ß6-α6 loop in the positive-subsite region of GH5_7 mannanases are absent in CapGH5_57, generating a large and open catalytic interface that might favor the binding of branched substrates. Supporting this, CapGH5_57 contains a tryptophan residue adjacent and perpendicular to the cleavage site, indicative of an anchoring site for a substrate with a substitution at the -1 glycosyl moiety. Taken together, these results suggest that despite presenting endo activity on glucomannan, CapGH5_57 may have a new type of substituted heteromannan as its natural substrate. This work demonstrates the still great potential for discoveries regarding the mechanistic and functional diversity of this large and polyspecific GH family by unveiling a novel catalytic interface sculpted to recognize complex heteromannans, which led to the establishment of the GH5_57 subfamily.

Mandibular morphometry applied to local anaesthetic blockage in the capybara (Hydrochoerus hydrochaeris).

Capybaras have been victims of collisions against vehicles, which can result in fractures of the teeth and mandible. Then, a local anaesthetic block of the inferior alveolar and mental nerves is important for performing therapeutic procedures in the oral cavity of these rodents. Thus, the aim of this study was to describe the mandibular morphometry of the capybara with emphasis on the establishment of anatomic references for anaesthetic block of the inferior alveolar and mental nerves. For this, mandibles from eight young and adult capybaras were used. Radiography and morphometry of the capybara hemimandible were performed. The mandibular foramen had a dorsoventral diameter of 2.1 mm in young and 2.2 mm in adult capybaras, and it was situated ventrally to the third molar tooth. For extraoral block of the inferior alveolar nerve, the needle should be introduced obliquely 63.5 and 77.4 mm from the angular process in young and adult capybaras, respectively. In another extraoral approach, the needle should be introduced perpendicularly 20.8 mm in young and 26.3 mm in adult animals from the ventral margin of the capybara mandible. For blocking only the mental nerve, the needle should be inserted perpendicularly from the interalveolar margin, 10.7 and 11.5 mm in the young and adult capybaras, respectively. The findings of this study suggest that the age group should be taken into account when performing the anaesthetic block of the inferior alveolar and mental nerves in capybaras.

Update of Cestodes Parasitizing Neotropical Hystricomorphic Rodent.

This review aims at identifying cestodes that are present in hunted rodent species in the neo-tropical region. The rodent species that was investigated were the capybara (Hydrochoerus hydrochaeris, Linnaeus, 1766), lappe (Cuniculus paca, Linnaeus, 1766), agouti (Dasyprocta leporina, Linnaeus, 1758), chinchilla (Chinchilla chinchilla, Lichtenstein, 1829), Trinidad spiny rat (Proehimys trinitatus, Allen and Chapman, 1893), nutria (Myocastor coypus, Molina, 1782), and vizcacha (Lagostomus maximus, Desmarest, 1817). These rodent species are utilized for their meats in many rural communities in the Caribbean and South America. These rodents belong to the hystricomorphic group. Raillietina demerariensis Daniels, 1895 was commonly found in the gastrointestinal tract of D. leporina, C. paca and P. trinitatus. Similarly, in the liver, muscle and subcutaneous tissue the metacestodes on Echinococcus vogeli Daniels, 1895 and Echinococcus oligarthrus was found in the lappe and agouti. The capybara was found to have the most species of cestodes in its gastrointestinal tract when compared to the agouti and lappe. However, metacestodes were not recorded in the tissues of the capybara. This surprising feature shows the effect of the difference in feeding habits between the capybara and the agouti and lappe. The literature reviewed in this study includes scientific publications on cestodes and metacestodes of Hystricomorphic rodents. An exhaustive search was performed using the digital repositories in Google Scholar, Scielo, Redalyc, Scopus and Pubmed. Literature searched spanned the years 1970-2021. Cestodes of zoonotic significance were E. vogeli and E. oligarthrus, with humans becoming infected when consuming eggs of contaminated food and water. The agouti and lappe act as intermediate host in the life cycle of E. vogeli and E. oligarthrus, the definitive host (canids and felids) become infected by consuming of tissue infected with metacestodes. Humans become infected through the ingestion of eggs from the definitive host where cystic lesions develop in the liver, lungs and other abdominal organs.

Reproductive Technologies Used in Female Neo-Tropical Hystricomorphic Rodents.

This is the second of two literature reviews that focuses on the female reproductive anatomy and reproductive technologies used in selected neo-tropical hystricomorphic rodents. The rodents chosen included the agouti (Dasyprocta leporina), the capybara (Hydrochoerus hydrochaeris), and the paca (Cuniculus paca). Over seventy references were used, spanning the years 1919-2021. Knowledge of the reproductive tract is important in understanding any unique features, which may affect the use of reproductive technologies. Some unique characteristics common to these species included the presence of a vaginal closure membrane and a lobulated placenta with a vascular sub-placenta. The capybara had hyperpigmentation of the vagina that was unique to each individual, while the agouti and paca had accessory corpora lutea, in addition to the main one. Some reproductive technologies have been used, with attempts at estrous induction and synchronization taking place within the past five years. Even though most work has been done over the past twenty years, there is still a dearth of information.

Molecular survey of Leishmania spp. in skin samples of capybaras (Hydrochoerus hydrochaeris) from different areas of Brazil / Investigação molecular de Leishmania spp. em amostras de pele de capivaras (Hydrochoerus hydrochaeris) de diferentes regiões do Brasil

Leishmaniases comprise a spectrum of diseases caused by protozoan parasites of the genus Leishmania, with some species of rodents being incriminated as reservoirs. The capybara is the largest extant rodent species in the world and is widely distributed in South America. The occurrence of infection by Leishmania spp. was investigated in capybaras captured in Brazil during 2015­2019 from established populations in five highly anthropic areas of the state of São Paulo and two natural areas of the states of Mato Grosso and Mato Grosso do Sul. A total of 186 individuals were captured and subjected to abdominal skin biopsy. All skin samples were Leishmania kDNA-negative, suggesting that capybaras have no role in the transmission cycles of Leishmania species in the studied areas despite the well-known role of other rodents in the life cycle of Leishmania spp.(AU)

As leishmanioses compreendem um espectro de doenças causadas por protozoários do gênero Leishmania e algumas espécies de roedores são incriminadas como reservatórios de Leishmania spp. As capivaras compreendem a maior espécie de roedores existentes e são amplamente distribuídas na América do Sul. Para investigar a ocorrência de infecção por Leishmania spp. em capivaras, durante os anos de 2015-2019 capivaras foram capturadas em cinco áreas antrópicas do estado de São Paulo e em duas áreas naturais dos estados do Mato Grosso e do Mato Grosso do Sul, todos esses ambientes com populações de capivaras estabelecidas. Um total de 186 indivíduos foram capturados e submetidos à biópsia de pele abdominal. Todas as amostras de pele foram negativas para o alvo kDNA, assim, os dados sugerem que nas áreas estudadas as capivaras não têm papel no ciclo de transmissão de espécies de Leishmania spp., apesar do papel bem conhecido de outros roedores no ciclo de vida de Leishmania spp.(AU)

Clay Nanotube Immobilization on Animal Hair for Sustained Anti-Lice Protection.

Topical administration of drugs is required for the treatment of parasitic diseases and insect infestations; therefore, fabrication of nanoscale drug carriers for effective insecticide topical delivery is needed. Here we report the enhanced immobilization of halloysite tubule nanoclay onto semiaquatic capybaras which have hydrophobic hair surfaces as compared to their close relatives, land-dwelling guinea pigs, and other agricultural livestock. The hair surface of mammals varies in hydrophobicity having a cortex surrounded by cuticles. Spontaneous 1-2 µm thick halloysite hair coverages on the semi-aquatic rodent capybara, non-aquatic rodent guinea pig, and farm goats were compared. The best coating was found for capybara due to the elevated 5 wt% wax content. As a result, we suggest hair pretreatment with diluted wax for enhanced nanoclay adsorption. The formation of a stable goat hair coverage with a 2-3 µm halloysite layer loaded with permethrin insecticide allowed for long-lasting anti-parasitic protection, enduring multiple rain wettings and washings. We expect that our technology will find applications in animal parasitosis protection and may be extended to prolonged human anti-lice treatment.

Parasites Circulating in Wild Synanthropic Capybaras (Hydrochoerus hydrochaeris): A One Health Approach.

Capybaras (Hydrochoerus hydrochaeris) are affected by a wide range of protozoan and metazoan-derived parasitic diseases. Among parasites of free-ranging capybaras are soil-, water-, food- and gastropod-borne parasitosis, today considered as opportunistic infections in semiaquatic ecosystems. The overlapping of the capybara's natural ecological habitats with human and domestic animal activities has unfortunately increased in recent decades, thereby enhancing possible cross- or spillover events of zoonotic parasites. Due to this, three synanthropic wild capybara populations in the Orinoco Basin were studied for the occurrence of gastrointestinal parasite infections. A total of forty-six fecal samples were collected from free-ranging capybaras in close proximity to livestock farms. Macroscopical analyses, standard copromicroscopical techniques, coproELISA, PCR, and phylogenetic analysis revealed thirteen parasite taxa. In detail, the study indicates stages of five protozoans, four nematodes, one cestode, and three trematodes. Two zoonotic parasites were identified (i.e., Plagorchis muris, and Neobalantidium coli). The trematode P. muris represents the first report within South America. In addition, this report expands the geographical distribution range of echinocoelosis (Echinocoleus hydrochoeri). Overall, parasitological findings include two new host records (i.e., P. muris, and Entamoeba). The present findings collectively constitute baseline data for future monitoring of wildlife-derived anthropozoonotic parasites and call for future research on the health and the ecological impact of this largest semiaquatic rodent closely linked to humans, domestic and wild animals.

Molecular detection of piroplasmids in synanthropic rodents, marsupials, and associated ticks from Brazil, with phylogenetic inference of a putative novel Babesia sp. from white-eared opossum (Didelphis albiventris).

The order Piroplasmida encompasses tick-borne pathogens of veterinary and medical importance positioned in two main families: Babesiidae and Theileriidae. Even though previous studies carried out in Brazil recorded the occurrence of piroplasmid species circulating in small mammals, 18S RNA gene sequences were only partially sequenced, preventing the assessment of their phylogenetic positioning. The current study aimed to detect and characterize, using morphological, molecular, and bioinformatic approaches, piroplasmids from wild mammals and associated ticks sampled in Central-Western Brazil. Out of 67 Didelphis albiventris sampled, 22 (16.4%) were positive for piroplasmids by PCR. In contrast, none of the 48 small rodents and 14 capybaras (Hydrochoerus hydrochaeris) was PCR-positive. Four Amblyomma dubitatum ticks-one from Rattus rattus, one from H. hydrochaeris, and two from D. albiventris-out of 114 Amblyomma spp. DNA samples were positive for piroplasmids by PCR. The phylogenetic inference performed using the near-complete 18S rRNA gene positioned the putative novel piroplasmid species detected in D. albiventris and associated A. dubitatum ticks near to Babesia sensu lato clade (Western group-cluster III) and distant from the Australian marsupial-associated piroplasms. Phylogenetic inferences based on two additional molecular markers, namely hsp-70 and cox-1, supported the near-complete 18S rRNA gene phylogenetic inference. Finally, the partial 18S rRNA gene sequences detected in ticks from rodents (R. rattus and H. hydrochaeris) showed 97.2-99.4% identity with the Piroplasmida previously detected in a capybara from Brazil, raising evidence that a still uncharacterized piroplasmid species has been identified in the capybara, the largest rodent species from South America.

Morphometric Patterns and Blood Biochemistry of Capybaras (Hydrochoerus hydrochaeris) from Human-Modified Landscapes and Natural Landscapes in Brazil.

The capybara, Hydrochoerus hydrochaeris, is the largest extant rodent of the world. To better understand the correlation between size and body mass, and biochemical parameters of capybaras from areas with different degrees of anthropization (i.e., different food supplies), we sampled free-ranging capybaras from areas of natural landscapes (NLs) and human-modified landscapes (HMLs) in Brazil. Analyses of biometrical and biochemical parameters of capybaras showed that animals from HMLs were heavier (higher body mass) than those from NL, a condition possibly related to fat deposit rather than body length, as indicated by Body Condition Index (BCI) analyses. Biochemical parameters indicated higher serum levels of albumin, creatine kinase, cholesterol, fructosamine and total protein among capybaras from HMLs than from NLs; however, when all adult capybaras were analyzed together only cholesterol and triglycerides were positively correlated with body mass. We propose that the biochemical profile differences between HMLs and NLs are related to the obesity condition of capybaras among HMLs. Considering that heavier animals might live longer and reproduce more often, our results could have important implications in the population dynamics of capybaras among HMLs, where this rodent species is frequently represented by overgrowth populations that generate several levels of conflicts with human beings.

First molecular detection of Trypanosoma cruzi, T. rangeli and Leishmania spp. in capybaras.

Hydrochoerus hydrochaeris (capybara), is a widely distributed rodent in Latin America, with exploitation for food purposes and also used in leather industry products. The infection of this rodent by trypanosomatids may not be detected by parasitological methods, due to low parasitemias. The Capybaras blood samples from the Apure State were collected on filter paper, DNA was extracted and PCR was performed. The PCR technique was used for the detection of Trypanosoma cruzi satellite and kinetoplast DNA, T. rangeli miniexon, T. evansi RIME sequence, and DNA encoding ribosomal RNA and internal transcribed spacer 1 from Leishmania spp. Of the 16 evaluated samples, 12 (75%) were positive for T. cruzi, two for T. rangeli (12.5%), one for Leishmania spp. (6.3%) and none for T. evansi. Regarding coinfection, the two specimens infected with T. rangeli were also infected with T. cruzi (12.5%) and the positive sample for Leishmania spp. was also infected with T. cruzi (6.3%). The results shown in this study represent the first finding of T. cruzi infection, detected by molecular methods, world-wide and the first time that T. rangeli and Leishmania spp. have been found in capybaras. In addition, we report coinfections by T. cruzi/T. rangeli and T. cruzi/Leishmania spp. in H. hydrochaeris for the first time world-wide. Capybaras are widely managed as a source of animal protein, the results obtained require evaluating their possible role as a reservoir in trypanosomiasis and leishmaniasis. A 'One Health' approach through combination of ecological, veterinary and human health including the diagnosis and treatment of diseases of both humans and animals is essential for the development of more successful health programs.

Parasitism of a capybara (Hydrochoerus hydrochaeris) by Amblyomma nodosum Neumann, 1899 and Amblyomma humerale Koch, 1844 in an Amazon forest area, Rondônia, Brazil / [Parasitismo por Amblyomma nodosum Neumann, 1899 e Amblyomma humerale Koch, 1844 em capivara (Hydrochoerus hydrochaeris) em área de Floresta Amazônica, Rondônia, Brasil]

Dois carrapatos adultos, sendo um Amblyomma nodosum e um Amblyomma humerale foram encontrados parasitando ativamente uma capivara (Hydrochoerus hydrochaeris) proveniente da região central do estado de Rondônia, Brasil, na zona rural do município de Ji-Paraná, localizado na Amazônia ocidental. Poucos trabalhos científicos relatam a presença de A. humerale em capivaras. Assim, esta é a primeira vez que A. nodosum é relatado parasitando essa espécie animal. Por não se tratar de um hospedeiro animal conhecido para A. nodosum ou comum para A. humerale, esses achados podem sugerir uma nova relação entre hospedeiros para eles. Portanto, são necessários mais estudos acerca da ecologia desses parasitas, principalmente por serem potenciais transmissores de patógenos de importância em medicina veterinária e saúde pública.(AU)

Trichuris spp. in Animals, with Specific Reference to Neo-Tropical Rodents.

Trichuriasis is the clinical disease of animals infected with the parasite of the genus Trichuris. This review attempts to present information on Trichuris spp. infestation in neo-tropical rodents that are utilized for meat consumption by humans. Neo-tropical rodents utilized for meat production can be divided into two categories: those that have been domesticated, which include the guinea pig (Cavia porcellus), and those that are on the verge of domestication, such as the capybara (Hydrochoerus hydrochaeris), lappe (Cuniculus paca/Agouti paca), and agouti (Dasyprocta leporina). This document reviews the literature on the species of Trichuris that affects the rodents mentioned above, as well as the clinical signs observed. The literature obtained spans over sixty years, from 1951 to 2020. Trichuris spp. was found in these neo-tropical rodents mentioned. However, there is a dearth of information on the species of Trichuris that parasitize these animals. The capybara was the only rodent where some molecular techniques were used to identify a new species named T. cutillasae. In most cases, Trichuris spp. was found in combination with other endoparasites, and was found at a low prevalence in the lappe and guinea pig. The presence of Trichuris spp. ranged from 4.62-53.85% in the agouti, 4.21-10.00% in the lappe, 50% in the capybaras, and 1-31% in guinea pigs. Further work must be done towards molecular identification of various Trichuris spp. present in these rodents, as well as the clinical effect of infection on the performance of agouti, lappe, capybara, and guinea pigs.

Reproductive Technologies Used in Male Neo-Tropical Hystricomorphic Rodents.

This review, which is the first of two, focuses on the male reproductive anatomy and reproductive technologies used in Neo-tropical hystricomorphic rodents with the potential for domestication, which are the agouti (Dasyprocta leporina), the capybara (Hydrochoerus hydrochaeris) and the paca (Cuniculus paca). We consider over seventy references spanning from 1965 to 2020, with the majority of work being done in the past twenty years. Knowledge of the reproductive tract and reproductive technologies is critical to the conservation and preservation of these species. Although all three animals had similarities in their anatomy, such as no overt scrotums and testes located intra-abdominally in the inguinal region, some had unique features-for example, the agouti and the paca had penile spines, and two lateral penile cartilages. High spermatogenic efficiency was noted in the agouti and the paca, making them good candidates for increasing their reproductive performance in conservation programs. A review of the literature has shown that there is increasing work taking place on the reproductive technologies used in these animals; however, a lot of work is still lacking, as, to the author's knowledge, standard protocols and artificial insemination procedures are yet to be established.

The comparative aspects of hystricomorph subplacenta: potential endocrine organ.

BACKGROUND: The placenta of hystricomorph rodents, lagomorphs and some primates includes an unusual structure, termed a subplacenta, which essentially consists of trophoblastic cells located deep to the central implantation site within the area of decidualization. It has been suggested that the subplacenta is functionally important, although considerable controversy remains on the issue. In this context, our objective was to compare the architecture and structure of the subplacentas of different hystricomorph species, to investigate the possibility that it is active in hormone synthesis. METHODS: In total, the placentas of 3 capybaras (Hydrochaeris hydrochaeris), 2 pacas (Agouti paca), 5 agoutis (Dasyprocta leporina), 5 rock cavies (Kerodon rupestris) and 3 guinea pigs (Cavia porcellus) at different stages of pregnancy (early, middle and near term) were used for gross and microscopic examination. This included the preparation of latex injection casts, immunohistochemistry for steroidogenic enzymes, scanning and transmission electron microscopy. Tissue steroid concentrations were also determined. RESULTS: The gross morphology and microvascular arrangement of the subplacentas were similar among the hystricomorphs studied including ultra-structural verification of cytotrophoblast and syncytiotrophoblast in all species. In guinea pigs, trophoblast cells exhibited characteristics consistent with intense metabolic and secretory activity in general. However, immuno-histochemical evidence also indicated that subplacental trophoblast expressed key steroidogenic enzymes, mainly in the chorionic villus region, consistent with tissue steroid concentrations. CONCLUSIONS: The subplacentas within placentas of hystricomorph rodent species are structurally similar and, in guinea pigs, have potential for steroid hormone secretion from, at least the early stages of pregnancy.

How to Make a Rodent Giant: Genomic Basis and Tradeoffs of Gigantism in the Capybara, the World's Largest Rodent.

Gigantism results when one lineage within a clade evolves extremely large body size relative to its small-bodied ancestors, a common phenomenon in animals. Theory predicts that the evolution of giants should be constrained by two tradeoffs. First, because body size is negatively correlated with population size, purifying selection is expected to be less efficient in species of large body size, leading to increased mutational load. Second, gigantism is achieved through generating a higher number of cells along with higher rates of cell proliferation, thus increasing the likelihood of cancer. To explore the genetic basis of gigantism in rodents and uncover genomic signatures of gigantism-related tradeoffs, we assembled a draft genome of the capybara (Hydrochoerus hydrochaeris), the world's largest living rodent. We found that the genome-wide ratio of nonsynonymous to synonymous mutations (ω) is elevated in the capybara relative to other rodents, likely caused by a generation-time effect and consistent with a nearly neutral model of molecular evolution. A genome-wide scan for adaptive protein evolution in the capybara highlighted several genes controlling postnatal bone growth regulation and musculoskeletal development, which are relevant to anatomical and developmental modifications for an increase in overall body size. Capybara-specific gene-family expansions included a putative novel anticancer adaptation that involves T-cell-mediated tumor suppression, offering a potential resolution to the increased cancer risk in this lineage. Our comparative genomic results uncovered the signature of an intragenomic conflict where the evolution of gigantism in the capybara involved selection on genes and pathways that are directly linked to cancer.

Effects of Lupron and surgical castration on fecal androgen metabolite concentrations and intermale aggression in capybaras (Hydrochoerus hydrochaeris).

To curb agonistic interactions in a bachelor group of three male capybaras (Hydrochoerus hydrochaeris), a single dose of leuprolide acetate (Lupron®) was used in an attempt to chemically sterilize the males. Concurrently, fecal androgen metabolite (FAM) concentrations were quantified via enzyme immunoassay to monitor changes in testosterone production after injection of the gonadotropin-releasing hormone agonist. When Lupron proved ineffective in suppressing intraspecific aggression, surgical castration was performed on two males, with continued noninvasive endocrine monitoring. In all three capybaras, FAM concentrations increased initially as a result of the luteinizing hormone surge, but then decreased significantly following chemical sterilization. Surgical castration resulted in further, persistent declines in FAM concentrations in two males, while the third, intact male demonstrated a rise in FAM to pre-Lupron concentrations at 8.5 and 9.5-month postadministration. Despite successful suppression of sperm and testosterone production, intermale aggression continued, ultimately necessitating separation of the animals and transfer to other holding institutions. Under this set of conditions, a single Lupron dose was inadequate for suppressing intraspecific aggression in a group of three males with a pre-established history of aggression.

Endoparasites of capybaras (Hydrochoerus hydrochaeris) from anthropized and natural areas of Brazil / Endoparasitas de capivaras (Hydrochoerus hydrochaeris) provenientes de áreas antropizadas e de áreas naturais do Brasil

Abstract This study aimed to evaluate the occurrence of endoparasites in fecal samples of capybaras from anthropized areas in seven cities in the state of São Paulo, southeastern Brazil, and natural areas in two locations in the Pantanal biome. For the parasitological evaluation of samples, feces were subjected to centrifugal sedimentation in water-ether and centrifugal flotation in sucrose solution. Out of the 113 samples examined, 97.3% (110/113) were positive for the presence of helminth eggs and/or protozoan oocysts, with 96.7% (89/92) and 100% (21/21) in capybaras from anthropized and natural areas, respectively. Helminth eggs belonging to the Class Cestoda (Monoecocestus spp.), Class Digenea, and Class Nematoda (Trichostrongyloidea, Strongyloides chapini, Protozoophaga obesa, and Capillaria hydrochoeri) were detected. Coccidia oocysts of Eimeria spp. and Cryptosporidium spp. were detected. The difference found was in the occurrence of S. chapini between anthropized and natural areas, as S. chapini was not detected in natural areas. Capybaras from anthropized areas showed a greater species richness of endoparasites, including species such as Fasciola hepatica and Cryptosporidium spp., that might have zoonotic potential.

Resumo O presente estudo apresentou como objetivo avaliar a ocorrência de endoparasitas nas amostras de fezes de capivaras de áreas antropizadas de sete cidades do Estado de São Paulo, Sudeste do Brasil, e áreas naturais de duas localidades do bioma Pantanal. Para a avaliação parasitológica das amostras de fezes foram empregadas as técnicas de centrífugo-sedimentação em água-éter e centrífugo-flutuação em solução de sacarose. De um total de 113 amostras examinadas, 97,3% (110/113) apresentaram resultados positivos para a presença de ovos de helmintos e/ou oocistos de protozoários. No geral, a positividade foi de 96,7% (89/92), e 100% (21/21) em capivaras de áreas antropizadas e naturais, respectivamente. Foram detectados ovos de helmintos pertencentes às Classes Cestoda (Monoecocestus spp.), Digenea e Nematoda (Trichostrongyloidea, Strongyloides chapini, Protozoophaga obesa e Capillaria hydrochoeri). Em relação aos protozoários, foram detectados oocistos dos coccídios Eimeria spp. e Cryptosporidium spp. A diferença encontrada foi na comparação da ocorrência de S. chapini em áreas antropizadas e naturais, sem detecção para esta última área. As capivaras provenientes das áreas antropizadas apresentaram uma maior riqueza de espécies de endoparasitas, incluindo as espécies Fasciola hepatica e Cryptosporidium spp., que podem apresentar potencial zoonótico.