Chinchilla spp. is a South American hystricomorph rodent genus currently considered almost extinct in the wild. The high quality of chinchilla fur motivated the harvesting of chinchillas for the fur market. Reproductive biology advances come from studies on commercially exploited animals, especially Chinchilla lanigera. We studied seasonal variation of urinary androgen metabolites, sperm concentration and sperm functional activity in males of domestic Chinchilla lanigera under natural photoperiod. In Córdoba city (31° S-64° W; Argentina), within the same latitudes as those of the historic Andean distribution (tropical deserts; 15°-34° S), domestic males (n=7) were studied in May (autumn), August (winter), November (spring), and February (summer). Urine was seasonally collected (over 24h; once for season, 4 in total) to measure urinary androgen metabolites (RIA), before semen collection by electroejaculation. The results indicated that although testicular volume (relative to body weight) and values of sperm functional activity did not show seasonal changes, a seasonal variation in androgen excretion was detected, with the highest values occurring during "short" light/dark cycles (autumn-winter). In addition, viable spermatozoa with intact acrosome mean values during winter-spring were higher than in autumn or summer. This study provides information that might contribute to the assessment of testicular activity in male chinchilla subjected to genetic selection in the fur industry. In addition, since domestic chinchilla still share some genomic characteristics with their counterparts in the wild, results presented may alsocontribute to ex situ breeding program of endangered chinchilla. In conclusion, natural photoperiod cycle affects testicular activity in domestic chinchilla.

The gastrointestinal microbiota develop alongside the host and play a vital role in the health of cecal fermenters such as chinchillas. However, little is known about the microbiota architecture in healthy chinchillas. Illumine-based 16S rRNA gene amplicon sequencing was used to investigate the microbiota present in six different gastrointestinal tract regions of three healthy adult chinchillas. The findings revealed significantly more abundant microbiota in the large intestine compared with the proximal segments. In addition, the cecum exhibited better evenness compared to the colon. The core microbiota are Firmicutes, Bacteroidota, Actinobacteriota, and Proteobacteria at the phylum level. The signature microbiota of each segment were identified. The cecum had 10 signature microbiota, which had the widest coverage and overlapped with that of the cecum. The stomach had five signature microbiota, exhibiting the second widest coverage and overlapping with the duodenum. No signature microbiota were detected in the jejunum and ileum. While similarities exist with the microbiota of other cecal fermenters, chinchillas exhibit distinct microbiota closely related to their unique digestive mechanisms. This study is a preliminary study of the gastrointestinal microbiota architecture and distribution in healthy chinchillas. Further study is needed in order to better understand the effect of gastrointestinal microbiota on the health of the chinchilla.

Several parameters are important when choosing the most appropriate animal to model human obstetrics, including gestation period, number of fetuses per gestation and placental structure. The domesticated long-tailed chinchilla (Chinchilla lanigera) is a well-suited and appropriate animal model of pregnancy that often will carry only one offspring and has a long gestation period of 105-115 days. Furthermore, the chinchilla placenta is of the haemomonochorial labyrinthine type and is therefore comparable to the human villous haemomonochorial placenta. This proof-of-concept study demonstrated the feasibility in laboratory settings, and demonstrated the potential of the pregnant chinchilla as an animal model for obstetric research and its potential usefulness for non-invasive measurements in the placenta. We demonstrate measurements of the placental and fetal metabolism (demonstrated in vivo by hyperpolarized MRI and in vitro by qPCR analyses), placental vessels (demonstrated ex vivo by contrast-enhanced CT angiography) and overall anatomy (demonstrated in vivo by whole-body CT).

Carboplatin, a drug widely used against solid head and neck tumors, selectively destroys cochlear inner hair cells and type I auditory nerve fibers in chinchilla. This should affect neurotransmitter chemistry, involving amino acids, where the type I auditory nerve fibers terminate in the cochlear nucleus. Using microdissection combined with high-performance liquid chromatography, amino acid concentrations were mapped in the cochlear nuclei of chinchillas injected intraperitoneally 6-8 weeks earlier with 100 mg/kg carboplatin and in those of control animals. Glutamate concentrations were 23% lower in the anteroventral cochlear nucleus (AVCN) and 40% lower in the posteroventral cochlear nucleus (PVCN) of carboplatin-injected chinchillas as compared to controls, while aspartate concentrations were 18% lower in AVCN and 27% lower in PVCN. Using a fluorometric assay, activities of glutaminase, an enzyme which catalyzes glutamate synthesis, were 30% lower in AVCN and 38% lower in PVCN of carboplatin-injected chinchillas. Concentrations of glutamine, gamma-aminobutyrate, and glycine were also lower in some ventral and dorsal cochlear nucleus regions of treated animals. These changes probably result mainly from both primary and later effects of reduced type I auditory nerve fiber input to the cochlear nucleus.

Inner ear damage can lead to hearing disorders, including tinnitus, hyperacusis, and hearing loss. We measured the effects of severe inner ear damage, produced by cochlear ablation, on the levels and distributions of amino acids in the first brain center of the auditory system, the cochlear nucleus. Measurements were also made for its projection pathways and the superior olivary nuclei. Cochlear ablation produces complete degeneration of the auditory nerve, which provides a baseline for interpreting the effects of partial damage to the inner ear, such as that from ototoxic drugs or intense sound. Amino acids play a critical role in neural function, including neurotransmission, neuromodulation, cellular metabolism, and protein construction. They include major neurotransmitters of the brain - glutamate, glycine, and γ-aminobutyrate (GABA) - as well as others closely related to their metabolism and/or functions - aspartate, glutamine, and taurine. Since the effects of inner ear damage develop over time, we measured the changes in amino acid levels at various survival times after cochlear ablation. Glutamate and aspartate levels decreased by 2weeks in the ipsilateral ventral cochlear nucleus and deep layer of the dorsal cochlear nucleus, with the largest decreases in the posteroventral cochlear nucleus (PVCN): 66% for glutamate and 63% for aspartate. Aspartate levels also decreased in the lateral part of the ipsilateral trapezoid body, by as much as 50%, suggesting a transneuronal effect. GABA and glycine levels showed some bilateral decreases, especially in the PVCN. These results may represent the state of amino acid metabolism in the cochlear nucleus of humans after removal of eighth nerve tumors, which may adversely result in destruction of the auditory nerve. Measurement of chemical changes following inner ear damage may increase understanding of the pathogenesis of hearing impairments and enable improvements in their diagnosis and treatment.

Septicaemia is the main pathological manifestation of Salmonella infection in chinchillas (Chinchilla lanigera), although information on its pathology is limited. We now describe the gross, histological and immunohistochemical features of Salmonella enterica subspecies enterica serotype Typhimurium (S. Typhimurium) infection in ranched chinchillas. Eighty-five adult pregnant chinchillas had anorexia, prostration, weight loss, hyperthermia and abortion. Necropsy of 13 animals revealed splenomegaly, hepatomegaly, mesenteric lymphadenomegaly, prominent Peyer's patches, pulmonary oedema, white pinpoint lesions in multiple organs and petechiae in the urinary bladder. In all cases, histological lesions were consistent with septicaemia, characterized by acute necrotizing hepatitis, splenitis, lymphadenitis, cystitis, pneumonia, enterocolitis, gastritis and/or nephritis. Immunohistochemistry for Salmonella spp on seven cases revealed intralesional immunolabelling in all affected organs. Salmonella sp was isolated from liver, spleen, intestinal contents and blood of 10 chinchillas. Isolates of four animals were identified as S. Typhimurium.

Giardia duodenalis is a parasitic protist that infects a large number of species, being localized in the small intestine. Two of the eight recognized assemblages have zoonotic potential, but studies regarding their distribution in less important pet or farm species are scarce. Of these species, the long-tailed chinchilla is a host for Giardia spp., although data on the spread of infection and assemblages involved are confined. The present work aimed to determine the prevalence of Giardia infection and assemblage identification in farmed chinchillas in Romania. A total of 341 fecal samples were collected from 5 farms and microscopically examined using flotation test based on saturated sodium chloride solution. DNA from all positive samples was extracted and identified by PCR targeting the gdh gene.

While metformin is the first-line pharmacological treatment of diabetes mellitus type 2, this drug is not considered safe to use in pregnant women because of its unknown consequences for the fetus. In this study, we aimed to investigate the biodistribution of metformin in the pregnant chinchilla, a species exhibiting placental characteristics comparable with the pregnant woman. Furthermore, we aimed to investigate the expression of metformin transporters in humans and chinchillas, respectively, in order to evaluate the pregnant chinchilla as a novel animal model for the use of metformin in pregnancy.

Rabbit, nutria and chinchilla testes were evaluated to compare testicular cellular senescence. There were no major species-specific differences in structure of either seminiferous tubules or interstitial tissue. There, however, were occasional abnormalities in seminiferous tubule structure with there being multinucleated and exfoliated cells present in rabbit testes. Furthermore, there were seminiferous tubules without a lumen that were filled with premeiotic/meiotic cells in nutria; and tubules with vacuolization with there being no post-meiotic cells in chinchillas. There were no differences in distribution or content of acids, total proteins and polysaccharides in the testis of any of the three species. Results using comparative immunohistochemistry procedures indicated the testes contained a few senescent cells in seminiferous tubules with typical morphology and there was a large number of senescent cells in seminiferous tubules of nutrias and chinchillas that had an abnormal structure (P <0.001). Compared to rabbit testes, in which there was the least number of senescent cells in seminiferous tubules, there was a greater abundance of senescence markers in both nutria and chinchilla testes (P < 0.05; P < 0.001, respectively). Furthermore, there were small abundances of caspase 3 and LC3 in the testes of all species. In chinchilla testes, there was a lesser concentration of cholesterol (P < 0.001) and testosterone compared with the other species. Cellular senescence in testes, therefore, can be assessed by detection of morpho-functional disorders of the testis of the three species evaluated in the present study.

Using a microchemical approach, we measured changes of amino acid concentrations in the chinchilla caudal posteroventral cochlear nucleus (PVCN) after cochlear ablation to determine to what extent slow decreases of glutamate and aspartate concentrations after carboplatin treatment resulted from slower effects of cochlear damage in chinchillas than in rats and guinea pigs, as opposed to effects of carboplatin treatment being slower than those of cochlear ablation. Our results indicate that both factors are involved: decreases of glutamate and aspartate concentrations after cochlear ablation are much slower in chinchillas than in rats and guinea pigs, but they are much faster than the decreases after carboplatin treatment. Further, aspartate and glutamate concentrations in the chinchilla caudal PVCN decreased by larger amounts after cochlear ablation than in rats or guinea pigs, and there was a transient increase of aspartate concentration at short survival times. Detailed mapping of amino acid concentrations in the PVCN of a chinchilla with 1 month survival after cochlear ablation and a rat with 7 days' survival indicated that the reductions of glutamate and aspartate occurred throughout the PVCN but were somewhat larger in ventral and caudal parts in chinchilla. Any decreases in the adjacent granular region were very small. There were also sustained bilateral decreases in concentrations of other amino acids, notably GABA and glycine, in the caudal PVCN of cochlea-ablated chinchillas but not rats. The effects of cochlear ablation on the concentrations of most of these other amino acids in chinchilla caudal PVCN differed from those of carboplatin treatment. Thus, although a major effect of auditory nerve damage on the cochlear nucleus-decreases of glutamate and aspartate concentrations-occurs across species and types of lesions, the details of timing and magnitude and the effects on other amino acids can vary greatly.

Fur-chewing is a common behavioral disorder developed by chinchillas kept in confinement that can indicate a past or present welfare problem. It also has a negative productive impact associated. The aim of this study was to determine the genetic component of fur-chewing, and the effect of this undesired behavior on fur price in a commercial fur-farming system of chinchillas (Chinchilla lanigera). The data for the analysis was derived from a commercial population of 10,196 chinchillas, recorded between the years 1990 and 2011. For determining differences in fur price according to presence of fur-chewing behavior, analysis of variance (ANOVA) was used, considering 3007 animals. For estimation of variance components of fur-chewing a sire-dam threshold (probit) mixed model was used, using data of 9, 033 individuals, and then heritability on the underlying liability scale was calculated. The analysis revealed a significant negative impact on fur price from fur-chewing chinchillas (p-value < 0.05). In addition, the study showed that fur-chewing presents significant genetic variation, with an estimated heritability of 0.16. The presentation of fur-chewing should be taken into account when selecting broodstock in these systems, in order to reduce the number of affected individuals.

There are two types of sensory cells in the mammalian cochlea, inner hair cells, which make synaptic contact with auditory-nerve afferent fibers, and outer hair cells that are innervated by crossed and uncrossed medial olivocochlear (MOC) efferent fibers. Contralateral acoustic stimulation activates the uncrossed efferent MOC fibers reducing cochlear neural responses, thus modifying the input to the central auditory system. The chinchilla, among all studied mammals, displays the lowest percentage of uncrossed MOC fibers raising questions about the strength and frequency distribution of the contralateral-sound effect in this species. On the other hand, MOC effects on cochlear sensitivity have been mainly studied in anesthetized animals and since the MOC-neuron activity depends on the level of anesthesia, it is important to assess the influence of anesthesia in the strength of efferent effects. Seven adult chinchillas (Chinchilla laniger) were chronically implanted with round-window electrodes in both cochleae. We compared the effect of contralateral sound in awake and anesthetized condition. Compound action potentials (CAP) and cochlear microphonics (CM) were measured in the ipsilateral cochlea in response to tones in absence and presence of contralateral sound. Control measurements performed after middle-ear muscles section in one animal discarded any possible middle-ear reflex activation. Contralateral sound produced CAP amplitude reductions in all chinchillas, with suppression effects greater by about 1-3 dB in awake than in anesthetized animals. In contrast, CM amplitude increases of up to 1.9 dB were found in only three awake chinchillas. In both conditions the strongest efferent effects were produced by contralateral tones at frequencies equal or close to those of ipsilateral tones. Contralateral CAP suppressions for 1-6 kHz ipsilateral tones corresponded to a span of uncrossed MOC fiber innervation reaching at least the central third of the chinchilla cochlea.

Streptococcus pneumoniae infections result in a range of human diseases and are responsible for almost one million deaths annually. Pneumococcal disease is mediated in part through surface structures and an anti-phagocytic capsule. Recent studies have shown that nonencapsulated S. pneumoniae (NESp) make up a significant portion of the pneumococcal population and are able to cause disease. NESp lack some common surface proteins expressed by encapsulated pneumococci, but express surface proteins unique to NESp. A chinchilla model of otitis media (OM) was used to determine the effect various pneumococcal mutations have on pathogenesis in both NESp and encapsulated pneumococci. Epithelial cell adhesion and invasion assays were used to examine the effects in relation to deletion of intrinsic genes or expression of novel genes. A mouse model of colonization was also utilized for comparison of various pneumococcal mutants. It was determined that pneumococcal surface protein K (PspK) and pneumolysin (Ply) affect NESp middle ear pathogenesis, but only PspK affected epithelial cell adhesion. Experiments in an OM model were done with encapsulated strains testing the importance of native virulence factors and treatment of OM. First, a triple deletion of the common virulence factors PspA, PspC, and Ply, (ΔPAC), from an encapsulated background abolished virulence in an OM model while a PspC mutant had detectable, but reduced amounts of recoverable bacteria compared to wildtype. Next, treatment of OM was effective when starting antibiotic treatment within 24 h with resolution by 48 h post-treatment. Expression of NESp-specific virulence factor PspK in an encapsulated strain has not been previously studied, and we showed significantly increased adhesion and invasion of human epithelial cells by pneumococci. Murine colonization was not significantly increased when an encapsulated strain expressed PspK, but colonization was increased when a capsule mutant expressed PspK. The ability of PspK expression to increase colonization in a capsule mutant despite no increase in adhesion can be attributed to other functions of PspK, such as sIgA binding or immune modulation. OM is a substantial economic burden, thus a better understanding of both encapsulated pneumococcal pathogenesis and the emerging pathogen NESp is necessary for effective prevention and treatment.

The nontypeable Haemophilus influenzae (NTHi) are associated with a spectrum of respiratory mucosal infections including: acute otitis media (AOM); chronic otitis media with effusion (COME); otorrhea; locally invasive diseases such as mastoiditis; as well as a range of systemic disease states, suggesting a wide range of virulence phenotypes. Genomic studies have demonstrated that each clinical strain contains a unique genic distribution from a population-based supragenome, the distributed genome hypothesis. These diverse clinical and genotypic findings suggest that each NTHi strain possesses a unique set of virulence factors that contributes to the course of the disease.

Moraxella catarrhalis causes significant health problems, including 15-20% of otitis media cases in children and ~10% of respiratory infections in adults with chronic obstructive pulmonary disease. The lack of an efficacious vaccine, the rapid emergence of antibiotic resistance in clinical isolates, and high carriage rates reported in children are cause for concern. In addition, the effectiveness of conjugate vaccines at reducing the incidence of otitis media caused by Streptococcus pneumoniae and nontypeable Haemophilus influenzae suggest that M. catarrhalis infections may become even more prevalent. Hence, M. catarrhalis is an important and emerging cause of infectious disease for which the development of a vaccine is highly desirable. Studying the pathogenesis of M. catarrhalis and the testing of vaccine candidates have both been hindered by the lack of an animal model that mimics human colonization and infection. To address this, we intranasally infected chinchilla with M. catarrhalis to investigate colonization and examine the efficacy of a protein-based vaccine. The data reveal that infected chinchillas produce antibodies against antigens known to be major targets of the immune response in humans, thus establishing immune parallels between chinchillas and humans during M. catarrhalis infection. Our data also demonstrate that a mutant lacking expression of the adherence proteins MhaB1 and MhaB2 is impaired in its ability to colonize the chinchilla nasopharynx, and that immunization with a polypeptide shared by MhaB1 and MhaB2 elicits antibodies interfering with colonization. These findings underscore the importance of adherence proteins in colonization and emphasize the relevance of the chinchilla model to study M. catarrhalis-host interactions.

Chinchillas are herbivores, but wild chinchillas may occasionally consume animal-based foods. The aim of this study was to determine the effect of fish meal (FM) and mealworm meal (MWM) included in complete pelleted diets on nutrient digestibility and gastrointestinal function in chinchillas. The experiment was performed on 24 male, divided into three groups, n=8. Control group (C) was fed a diet containing 10% soybean meal (SBM). In the experimental group FM, chinchillas received a diet containing 3% fish meal, and the diet administered to the experimental group MWM was supplemented with 4% dried mealworm larvae meal. The nutrient digestibility of diets was determined. At the end of the experiment animals were euthanized and their digestive tracts were removed to analyze gut activity. FM group animals were characterized by lower crude fat digestibility, whereas both alternative protein sources improved the digestibility of acid detergent fiber (ADF). A considerable increase in the activity of cecal intracellular and extracellular bacterial enzymes (in particular β-glucosidase, β-galactosidase and β-xylosidase) was noted in the FM group, which however did not increase the concentrations of short-chain fatty acids (SCFA). The inclusion of MWM in chinchilla diets shifted the bacterial fermentation site from the cecum (lowest SCFA pool) to the colon (highest SCFA pool), thus enabling to derive additional energy from less digestible dietary components. In conclusion, chinchilla diets can be supplemented with small amounts of animal protein such as fish meal and dried mealworm larvae meal.

Haemophilus influenzae is a significant cause of childhood otitis media, and also has an absolute growth requirement for heme. Recent microarray studies using three H. influenzae isolates were used to propose a putative core of genes responsive to iron and heme levels. Included in the core modulon were thirty seven genes that are preferentially expressed under iron/heme limitation, most of which are directly involved with iron and or heme acquisition. In this report, the core iron/heme modulon was further refined following microarray analysis of two additional nontypeable H. influenzae isolates from patients with otitis media. The transcriptional status of the genes comprising the refined iron/heme core modulon was then assessed in vivo, in a chinchilla model of otitis media. These in vivo experiments were performed to address the hypothesis that iron and heme regulated genes are both highly expressed in vivo and important, during clinical infection.

The purpose of this study was to investigate the morphological changes of round window membrane (RWM) in chinchillas with Streptococcus pneumoniae (S. pneumoniae) serotype 7F induced acute otitis media (AOM) by two dimensional (2D) and three dimensional (3D) measurements.

Ultrasound is a noninvasive routine method that allows real-time monitoring of fetal development in utero to determine gestational age and to detect congenital anomalies and multiple pregnancies. To date, the developmental biology of Chinchilla lanigera has not yet been characterized. This species has been found to undergo placentation, long gestation, and fetal dimensions similar to those in humans. The aim of this study was to assess the use of high-frequency ultrasound (HFUS) and clinical ultrasound (US) to predict gestational age in chinchillas and evaluate the possibility of this species as a new animal model for the study of human pregnancy. In this study, 35 pregnant females and a total of 74 embryos and fetuses were monitored. Ultrasound examination was feasible in almost all chinchilla subjects. It was possible to monitor the chinchilla embryo with HFUS from embryonic day (E) 15 to 60 and with US from E15 to E115 due to fetus dimensions. The placenta could be visualized and measured with HFUS from E15, but not with US until E30. From E30, the heartbeat became detectable and it was possible to measure fetal biometrics. In the late stages of pregnancy, stomach, eyes, and lenses became visible. Our study demonstrated the importance of employing both techniques while monitoring embryonic and fetal development to obtain an overall and detailed view of all structures and to recognize any malformation at an early stage. Pregnancy in chinchillas can be confirmed as early as the 15th day postmating, and sonographic changes and gestational age are well correlated. The quantitative measurements of fetal and placental growth performed in this study could be useful in setting up a database for comparison with human fetal ultrasounds. We speculate that, in the future, the chinchilla could be used as an animal model for the study of US in human pregnancy.

Gene modification technologies play a vital role in the study of biological systems and pathways. Although there is widespread and beneficial use of genetic mouse models, potential shortcomings of gene targeting technology exist, and are not always taken into consideration. Oversights associated with the technology can lead to misinterpretation of results; for example, ablation of a gene of interest can appear to cause an observed phenotype when, in fact, residual embryonic stem cell-derived genetic material in the genetic background or in the area immediately surrounding the ablated gene is actually responsible. The purpose of this review is to remind researchers, regardless of scientific discipline, that the background genetics of a knockout strain can have a profound influence on any observed phenotype. It is important that this issue be appropriately addressed during data collection and interpretation.