Estrogen regulated transcription of the non-estrogen-regulated hamster uteroglobin gene in MCF-7 cells.

To study the estrogen regulated transcription of the uteroglobin (UG) gene, the founding member of the secretoglobin family widely expressed in many different mammalian species, we re-created functional estrogen response elements (EREs) in the UG gene promoter from a species where UG expression is not regulated by estrogens: the hamster Mesocricetus auratus (Ma), to ascertain if the lack of functional EREs is the real cause of its estrogen insensitivity. Functional EREs in the hamster promoter, including the consensus ERE (cERE), failed to respond to an appropriate estrogen stimulus compared with its estrogen regulated ortholog from the brown hare Lepus capensis (Lc). As the nucleotide sequence is the only difference between genetic constructs from these two species, we suspected that the UG promoter from the hamster probably contains cis-acting genetic elements that negatively impairs the estrogen-regulated transcription mediated by the functional ERE. Accordingly, we prepared chimeric DNA constructs which eventually allowed to identify a region located 29 base pairs (bp) downstream of the ERE as responsible for the lack of estrogen-responsiveness of the Ma-UG gene in the breast cancer cell line MCF-7. This region contains the sequence ACACCCC which has been identified as the core sequence of the Sp/ Krüppel-like factor (KLF) family of transcription factors. This finding is relevant, not only due to the observation on a novel mechanism that control estrogen-induced transcription, but also because it may encourage further investigation for better defining specific genes with an ERE that do not respond to estrogen signaling in MCF-7 cells, a cell line widely employed as an in vitro model in breast cancer research.

Organ-specific immune profiling of Leishmania donovani-infected hamsters.

Visceral leishmaniasis (VL) is a neglected disease with a broad spectrum of clinical manifestations and involvement of visceral organs. Organ-specific immune response against the Leishmania donovani (Ld) complex is not yet understood due to the unavailability of an appropriate experimental model. In reference to our recent work on comparing the hamster model with VL patients, it is now possible to understand immune profiling in different visceral organs. This may offer an answer to varying parasite loads in different visceral organs in the same host. Herein, we analysed a panel of immune markers (Th-2/Th-1) in visceral organs of Ld-infected hamsters and quantified parasitic load in the same tissues using qPCR assay. In spleen, liver, bone marrow and lymph node (mesenteric) from Ld-infected hamsters, the parasite burden was quantified along with mRNA expression of a panel of Th-2 and Th-1 type immune markers, namely IL-10, IL-4, Arginase-I, GATA-3, SOCS-3, IL-12, IFN-γ, iNOS, T-bet and SOCS-5. A clear dichotomy was absent between Th-2 and Th-1 type immune markers and the major players of this immune response were IFN-γ, IL-10, T-bet, GATA-3, SOCS-5 and SOCS-3.

Hamster polyomavirus-associated T-cell lymphomas in Syrian hamsters (Mesocricetus auratus).

Hamster polyomavirus (HaPyV) infection has been associated with lymphomas in Syrian hamsters. In the present study, 14 cases of lymphoma in pet Syrian hamsters were pathologically examined and the involvement of HaPyV was investigated. Among 14 cases, 11 were abdominal and 3 were cutaneous lymphomas. The average ages of hamsters with abdominal lymphoma and cutaneous lymphoma were 7 months (range: 4-12 months) and 14 months (range: 6-23 months), respectively. Histologically, abdominal lymphomas were characterized by the diffuse growth of tumor cells with intermediate or large nuclei, low mitotic rates, the presence of tingible body macrophages, and the T-cell immunophenotype. Furthermore, 4/11 abdominal lymphomas were immunopositive for T-cell intracellular antigen-1, suggesting cytotoxic T-cell lymphomas. Cutaneous lymphomas were diagnosed as nonepitheliotropic T-cell lymphoma. Polymerase chain reaction (PCR) detected HaPyV DNA in 12/14 samples, and a sequence analysis of PCR amplicons confirmed >99% nucleotide identity to the published HaPyV sequences. In situ hybridization (ISH) for HaPyV DNA resulted in diffuse nuclear signals within tumor cells in 10/14 cases. Consistent with previous findings, all HaPyV-associated lymphomas were observed in the abdominal cavity of young hamsters. Polymerase chain reaction and ISH were useful for identifying the involvement of HaPyV in lymphomas, and ISH results indicated the presence of episomal HaPyV in neoplastic lymphocytes. The present study suggests that HaPyV infection is highly involved in abdominal lymphomas in young pet Syrian hamsters in Japan and provides diagnostic information on HaPyV-associated lymphoma.

Mitochondrial DNA Diversity of Mesocricetus auratus and Other Cricetinae Species among Cricetidae Family.

Unique anatomical and physiological features have made hamster species desirable research models. Comparative genomics and phylogenetic analysis of the hamster family members to clarify their evolution and genetic relationship, can provide a genetic basis for the comprehension of the variable research results obtained using different hamster models. The Syrian golden hamster (Mesocricetus auratus) is the most widely used species. In this study, we sequenced the complete mitochondrial genome (mitogenome) of M. auratus, compared it with the mitogenome of other Cricetinae subfamily species, and defined its phylogenetic position in the Cricetidae family. Our results show that the mitogenome organization, gene arrangement, base composition, and genetic analysis of the protein coding genes (PCGs) of M. auratus are similar to those observed in previous reports on Cricetinae species. Nonetheless, our analysis clarifies some striking differences of M. auratus relative to other subfamily members, namely distinct codon usage frequency of TAT (Tyr), AAT (Asn), and GAA (Glu) and the presence of the conserved sequence block 3 (CSB-3) in the control region of M. auratus mitogenome and other hamsters (not found in Arvicolinae). These results suggest the particularity of amino acid codon usage bias of M. auratus and special regulatory signals for the heavy strand replication in Cricetinae. Additionally, Bayesian inference/maximum likelihood (BI/ML) tree shows that Cricetinae and Arvicolinae are sister taxa sharing a common ancestor, and Neotominae split prior to the split between Cricetinae and Arvicolinae. Our results support taxonomy revisions in Cricetulus kamensis and Cricetulus migratorius, and further revision is needed within the other two subfamilies. Among the hamster research models, Cricetulus griseus is the species with highest sequence similarity and closer genetic relationship with M. auratus. Our results show mitochondrial DNA diversity of M. auratus and other Cricetinae species and provide genetic basis for judgement of different hamster models, promoting the development and usage of hamsters with regional characteristics.

Establishment of monoclonal antibodies to evaluate the cellular immunity in a hamster model of L infantum infection.

Syrian hamsters (Mesocricetus auratus) are largely used as a model for infectious diseases because it is very susceptible to several pathogens, including Leishmania spp. parasites. However, the research community faces limitations in its use due to the lack of immunological reagents and tools to study the immune system in this model. In this context, we proposed the validation of some important commercially anti-mouse mAbs (CD4, TNF-α, IFN-γ and IL-10) and how this could be useful to evaluate a specific cellular immune response in Leishmania-infected hamster using flow cytometry experiments. Our data demonstrated a cross-reactivity between these anti-mouse mAbs and hamster molecules that were herein studied. Beyond that, it was able to characterize the development of a specific cellular immune response through cytokine production in L infantum-infected hamsters when compared to uninfected ones. These data not only aid the usage of hamsters as experimental model to investigate various infectious diseases, but they contribute to the design of novel approaches to further investigate the immunological mechanisms associated to pathogen infections.

Hamster, a close model for visceral leishmaniasis: Opportunities and challenges.

AIM: Visceral leishmaniasis (VL) caused by parasites belonging to genus Leishmania (L.) is classified as a category I disease by the TDR/WHO. The understanding of the pathogenesis of this disease was built from the findings of available experimental models. Among all available models, the Syrian hamster (Mesocricetus auratus) is the most suitable model for the experimental representation of VL. In this review, we have focused on the opportunities and challenges of using the hamster as an experimental model for visceral leishmaniasis. METHODS: The studies referenced in this review were based on searches in PubMed and Google Scholar without a specific timeline. We collected study results underlining the clinicopathological response, immunopathogenesis and factors determining the outcome of VL in hamsters. Particular emphasis was given in the context of developing new therapeutics and testing potential candidates for vaccine development. CONCLUSION: Among all animal models, M. auratus is undoubtedly a better animal model for immunopathogenesis, drug discovery and vaccine development studies of VL infection. But, further optimization of this animal model is required to mimic human VL completely.

Parasitic load determination by differential expressions of 5-lipoxygenase and PGE2 synthases in visceral leishmaniasis.

Infection with L. donovani affects mainly visceral organs. Importantly, the parasitic load differs in different visceral organs; therefore there is a need to understand the organ specific immune regulation, particularly in the spleen and liver. Comparative studies between these organs in Leishmania infected hamster (Mesocricetus auratus) are lacking. Our study highlights the importance of eicosanoids in the organ specific pathology of visceral leishmaniasis. Among other immune cells, macrophages (mφ) which harbor Leishmania parasite are major producers of eicosanoids. In this study, we intend to explore linkage between organ specific immune response and eicosanoids. We suggest that eicosanoids (early immune modulators) and their organ specific expressions, possibly tune the outcome of mφ differently at different sites. We have observed that liver showed better containment of parasitic load than spleen, where we have found higher expression of 5-lipoxygenase (5-LO) enzyme along with IL-12 and iNOS. However, in spleen, enzymes of the PGE2 pathway i.e. PGE2 synthases (cytosolic and microsomal) along with IL-10 were predominantly higher. To further corroborate our findings, in vitro assays were carried out using purified eicosanoids (LTB4 and PGE2) and the inhibitors of these pathways. Findings establish that the 5-lipoxygenase pathway (i.e. LTB4) is anti-parasitic and its inhibition increases the parasitic load (qPCR based kDNA detection). On the contrary, PGES pathway (i.e. PGE2) supports establishment of infection in mφ. Taken together, 5-LO pathway plays a protective role in liver during L. donovani infection. However, the PGES pathway favors the parasite growth, particularly in the spleen at a later stage.

Efficacy of a New Recrystallized Enrofloxacin Hydrochloride-Dihydrate against Leptospirosis in a Hamster Model.

A trial on Syrian hamsters (Mesocricetus auratus) infected with Leptospira interrogans serovar Canicola was established to compare treatment efficacies of daily intramuscular (i.m.) injections of either 10 mg/kg of 5% enrofloxacin (Baytril [BE]; Bayer Animal Health, Mexico) or the same dose of enrofloxacin hydrochloride-dihydrate (enro-C). Hamsters were experimentally infected via the oral submucosa with 400 microorganisms/animal, in a sequential time schedule aligned to the initial treatment day, and were treated in groups as follows: a group treated with 5% enrofloxacin daily for 7 days after 24 h of infection (group BE24); a group treated as described for group BE24 but with enro-C (enro-C24); a group also treated with 5% enrofloxacin but starting at 72 h after infection (BE74); a group treated as described for group BE74 but with injection of enro-C (enro-C74). An untreated-uninfected control group (group CG-) and an infected-untreated control group (group CG+) were assembled (n = 18 in all groups). Weights and temperatures of the hamsters were monitored daily for 28 days. After hamsters were euthanatized or following death, necropsy, histopathology, macroscopic agglutination tests (MAT), bacterial culture, and PCR were performed. The mortality rates were 38.8% in group BE24 and 100% in group BE74 No mortality was observed in group enro-C24, and 11.1% mortality was recorded in group enro-C74 The mortality rates in groups CG+ and CG- were 100% and zero, respectively. Combined necropsy and histopathologic findings revealed signs of septicemia and organ damage in groups BE24, BE72, and CG+ Groups enro-C24 and CG- showed no lesions. Moderated lesions were registered in 3 hamsters in group enro-C72 MAT results were positive in 83.3% of BE24 hamsters (83.3%) and 100% of BE72 and CG+ hamsters; MAT results were positive in 16.7% in group Enro-C24 and 38.9% in group enro-C72 Only 4/18 were PCR positive in group enro-C72 and only 1 in group enro-C24 (P < 0.05). It can be concluded that enro-C may be a viable option to treat leptospirosis in hamsters and that this may be the case in other species.

Syrian Hamsters as a Small Animal Model for Emerging Infectious Diseases: Advances in Immunologic Methods.

The use of small animal models for the study of infectious disease is critical for understanding disease progression and for developing prophylactic and therapeutic treatment options. For many diseases, Syrian golden hamsters have emerged as an ideal animal model due to their low cost, small size, ease of handling, and ability to accurately reflect disease progression in humans. Despite the increasing use and popularity of hamsters, there remains a lack of available reagents for studying hamster immune responses. Without suitable reagents for assessing immune responses, researchers are left to examine clinical signs and disease pathology. This becomes an issue for the development of vaccine and treatment options where characterizing the type of immune response generated is critical for understanding protection from disease. Despite the relative lack of reagents for use in hamsters, significant advances have been made recently with several hamster specific immunologic methods being developed. Here we discuss the progress of this development, with focus on classical methods used as well as more recent molecular methods. We outline what methods are currently available for use in hamsters and what is readily used as well as what limitations still exist and future perspectives of reagent and assay development for hamsters. This will provide valuable information to researchers who are deciding whether to use hamsters as an animal model.

Ambient temperature affects postnatal litter size reduction in golden hamsters.

BACKGROUND: To better understand how different ambient temperatures during lactation affect survival of young, we studied patterns of losses of pups in golden hamsters (Mesocricetus auratus) at different ambient temperatures in the laboratory, mimicking temperature conditions in natural habitats. Golden hamsters produce large litters of more than 10 young but are also known to wean fewer pups at the end of lactation than they give birth to. We wanted to know whether temperature affects litter size reductions and whether the underlying causes of pup loss were related to maternal food (gross energy) intake and reproductive performance, such as litter growth. For that, we exposed lactating females to three different ambient temperatures and investigated associations with losses of offspring between birth and weaning. RESULTS: Overall, around one third of pups per litter disappeared, obviously consumed by the mother. Such litter size reductions were greatest at 30 °C, in particular during the intermediate postnatal period around peak lactation. Furthermore, litter size reductions were generally higher in larger litters. Maternal gross energy intake was highest at 5 °C suggesting that mothers were not limited by milk production and might have been able to raise a higher number of pups until weaning. This was further supported by the fact that the daily increases in litter mass as well as in the individual pup body masses, a proxy of mother's lactational performance, were lower at higher ambient temperatures. CONCLUSIONS: We suggest that ambient temperatures around the thermoneutral zone and beyond are preventing golden hamster females from producing milk at sufficient rates. Around two thirds of the pups per litter disappeared at high temperature conditions, and their early growth rates were significantly lower than at lower ambient temperatures. It is possible that these losses are due to an intrinsic physiological limitation (imposed by heat dissipation) compromising maternal energy intake and milk production.

PSA-NCAM in the posterodorsal medial amygdala is necessary for the pubertal emergence of attraction to female odors in male hamsters.

During puberty, attention turns away from same-sex socialization to focus on the opposite sex. How the brain mediates this change in perception and motivation is unknown. Polysialylated neural cell adhesion molecule (PSA-NCAM) virtually disappears from most of the central nervous system after embryogenesis, but it remains elevated in discrete regions of the adult brain. One such brain area is the posterodorsal subnucleus of the medial amygdala (MePD). The MePD has been implicated in male sexual attraction, measured here as the preference to investigate female odors. We hypothesize that PSA-NCAM gates hormone-dependent plasticity necessary for the emergence of males' attraction to females. To evaluate this idea, we first measured PSA-NCAM levels across puberty in several brain regions, and identified when female odor preference normally emerges in male Syrian hamsters. We found that MePD PSA-NCAM staining peaks shortly before the surge of pubertal androgen and the emergence of preference. To test the necessity of PSA-NCAM for female odor preference, we infused endo-neuraminidase-N into the MePD to deplete it of PSAs before female odor preference normally appears. This blocked female odor preference, which suggests that PSA-NCAM facilitates behaviorally relevant, hormone-driven plasticity.

Site-specific effects of gastrin-releasing peptide in the suprachiasmatic nucleus.

The effects of gastrin-releasing peptide (GRP) on the circadian clock in the suprachiasmatic nucleus (SCN) are dependent on the activation of N-methyl-d-aspartate (NMDA) receptors in the SCN. In this study, the interaction between GRP, glutamate and serotonin in the regulation of circadian phase in Syrian hamsters was evaluated. Microinjection of GRP into the third ventricle induced c-fos and p-ERK expression throughout the SCN. Coadministration of an NMDA antagonist or 8-hydroxy-2-di-n-propylamino-tetralin [a serotonin (5-HT)1A,7 agonist, DPAT] with GRP limited c-fos expression in the SCN to a region dorsal to GRP cell bodies. Similar to the effects of NMDA antagonists, DPAT attenuated GRP-induced phase shifts in the early night, suggesting that the actions of serotonin on the photic phase shifting mechanism occur downstream from retinorecipient cells. c-fos and p-ERK immunoreactivity in the supraoptic (SON) and paraventricular hypothalamic nuclei also increased following ventricular microinjection of GRP. Because of this finding, a second set of experiments was designed to test a potential role for the SON in the regulation of clock function. Syrian hamsters were given microinjections of GRP into the peri-SON during the early night. GRP-induced c-fos activity in the SCN was similar to that following ventricular administration of GRP. GRP or bicuculline (a γ-aminobutyric acidA antagonist) administered near the SON during the early night elicited phase delays of circadian activity rhythms. These data suggest that GRP-induced phase-resetting is dependent on levels of glutamatergic and serotonergic neurotransmission in the SCN and implicate activity in the SON as a potential regulator of photic signaling in the SCN.

Hepatic vascular changes associated with Opisthorchis felineus infection in Syrian hamsters and humans.

The liver fluke Opisthorchis felineus is a foodborne zoonotic pathogen endemic to Russia, Kazakhstan, and several European countries. The adult flukes affect the hepatobiliary system of piscivorous mammals and humans, thereby causing numerous complications, including liver fibrosis. Detailing the mechanisms of progression of the fibrotic complications is a hot topic in the field of research on opisthorchiasis pathogenesis. Pathologic angiogenesis appears to be associated with the fibrogenic progression due to active participation in the recruitment of inflammatory cells and many factors involved in the modulation of the extracellular matrix. The aim of the study was to evaluate neoangiogenesis and amyloid deposits in liver tissues of model animals and patients with confirmed chronic opisthorchiasis. In addition, we assessed a possible correlation of neoangiogenesis with liver fibrosis. We found a significant increase in the number of newly formed vessels and amyloid deposits in the liver of people with chronic opisthorchiasis compared to that of uninfected ones. Thus, for the first time we have demonstrated neoangiogenesis and amyloid deposits during O. felineus infection in a Mesocricetus auratus model. Regression analysis showed that CD34+ newly formed vessels correlate with fibrosis severity in the course of the infection. Our results indicate the potential contribution of angiogenesis to the progression of liver fibrosis, associated with O. felineus infection.

Hormonal changes and energy substrate availability during the hibernation cycle of Syrian hamsters.

Animals have to adapt to seasonal variations in food resources and temperature. Hibernation is one of the most efficient means used by animals to cope with harsh winter conditions, wherein survival is achieved through a significant decrease in energy expenditure. The hibernation period is constituted by a succession of torpor bouts (hypometabolism and decrease in body temperature) and periodic arousals (eumetabolism and euthermia). Some species feed during these periodic arousals, and thus show different metabolic adaptations to fat-storing species that fast throughout the hibernation period. Our study aims to define these metabolic adaptations, including hormone (insulin, glucagon, leptin, adiponectin, GLP-1, GiP) and metabolite (glucose, free fatty acids, triglycerides, urea) profiles together with body composition adjustments. Syrian hamsters were exposed to varied photoperiod and temperature conditions mimicking different phases of the hibernation cycle: a long photoperiod at 20 °C (LP20 group), a short photoperiod at 20 °C (SP20 group), and a short photoperiod at 8 °C (SP8). SP8 animals were sampled either at the beginning of a torpor bout (Torpor group) or at the beginning of a periodic arousal (Arousal group). We show that fat store mobilization in hamsters during torpor bouts is associated with decreased circulating levels of glucagon, insulin, leptin, and an increase in adiponectin. Refeeding during periodic arousals results in a decreased free fatty acid plasma concentration and an increase in glycemia and plasma incretin concentrations. Reduced incretin and increased adiponectin levels are therefore in accordance with the changes in nutrient availability and feeding behavior observed during the hibernation cycle of Syrian hamsters.

Leishmania (L.) infantum chagasi isolated from skin lesions of patients affected by non-ulcerated cutaneous leishmaniasis lead to visceral lesion in hamsters.

In Central America, Leishmania (L.) infantum chagasi infection causes visceral leishmaniasis (VL) and non-ulcerated cutaneous leishmaniasis (NUCL). The aim of the present study was to evaluate the course of an experimental infection in hamsters caused by L. (L.) infantum chagasi isolated from patients affected by NUCL compared with a strain isolated from a patient with VL. Stationary phase parasites in culture were inoculated through subcutaneous and intraperitoneal routes in hamsters. Following the post-infection times, a histopathological study, parasite load and cytokine determination in skin from the cutaneous inoculation site and viscera were performed. Animals subcutaneously infected with the different strains did not develop macroscopic lesions at the inoculation site, and the histopathological changes in the dermis were very slight. Regarding the histopathological study of the viscera, we observed the portal mononuclear inflammatory infiltrate, the presence of nodules in the hepatic parenchyma and the proliferation of macrophages in the spleen, which increased over the infection course. Overall, the parasite load in the liver and spleen and in the total IgG titres in the sera of infected hamster showed an increase with the time of infection, regardless of the route of inoculation. Regarding cellular immunity, we did not observe an increase or decrease in pro- and anti-inflammatory cytokines compared to the healthy control, except for IL-10, which was evident in the infected animals. The data showed that strains isolated from NUCL cause visceral lesions in the hamsters regardless of the route of inoculation, and they were similar to parasites isolated from VL humans.

Comparing the ontogeny, neurobiology, and function of social play in hamsters and rats.

Syrian hamsters show complex social play behavior and provide a valuable animal model for delineating the neurobiological mechanisms and functions of social play. In this review, we compare social play behavior of hamsters and rats and underlying neurobiological mechanisms. Juvenile rats play by competing for opportunities to pin one another and attack their partner's neck. A broad set of cortical, limbic, and striatal regions regulate the display of social play in rats. In hamsters, social play is characterized by attacks to the head in early puberty, which gradually transitions to the flanks in late puberty. The transition from juvenile social play to adult hamster aggression corresponds with engagement of neural ensembles controlling aggression. Play deprivation in rats and hamsters alters dendritic morphology in mPFC neurons and impairs flexible, context-dependent behavior in adulthood, which suggests these animals may have converged on a similar function for social play. Overall, dissecting the neurobiology of social play in hamsters and rats can provide a valuable comparative approach for evaluating the function of social play.

Dataset on DNA methylation and gene expression changes induced by 5-aza-2'-deoxycytidine in Syrian golden hamster fetal cell cultures.

The Syrian hamster (SH) is an animal model used in virology, toxicology, and carcinogenesis, where a better understanding of epigenetic mechanisms is required. Finding genetic loci regulated by DNA methylation may assist in the development of DNA methylation-based in vitro assays for the identification of carcinogens. This dataset informs on the regulation of gene expression by DNA methylation. Primary cultures of SH male fetal cells (sex determined by differences in kdm5 loci on the X and Y chromosome) were exposed for 7 days to the carcinogen benzo[a]pyrene (20 µM) from which a morphologically transformed colony was collected and reseeded. The colony bypassed senescence and sustained growth. After 210 days of culture, the cells were collected and divided in 16 aliquots to create 4 experimental groups to test the effects of the DNA methylation inhibitor 5-aza-2'-deoxycytidine (5adC). The experiment was initiated 24 h after cell seeding in 10 cm plates. The groups are naïve cells (N), cells exposed for 48 h to either 0.05% DMSO as vehicle (V), or to 5adC at 1 µM and 5 µM. DNA and RNA libraries were sequenced on an Illumina NextSeq 500. Gene expression was analysed by RNAseq and differentially methylated DNA regions (DMRs: clusters of 200 base pairs (bp), read depth >20, q< 0.05, methylation difference >|25%|) were identified by reduce representation bisulfite sequencing (RRBS). Global genome DNA methylation was similar between the N (mean±SD, 47.3%±0.02) and V groups (47.3%±0.01). Although 5adC reduced methylation, the reduction was larger in the 1 µM (39.2%±0.002) than in the 5 µM group (44.3%±0.01). 5adC induced a total of 612 and 190 DMRs by 1 µM and 5 µM, among which 79 and 23 were in the promoter regions (±3,000 bp from the transcription start site), respectively. 5adC induced a total of 1,170 and 1,797 differentially expressed genes (DEGs) by 1 µM and 5 µM, respectively. The 5 µM treatment induced statistically significant toxicity (% cell viability: group N 97%±8, V 98.8%±1.3, 1 µM 97.3%±0.5, 5 µM 93.8%±1.5), which perhaps reduced cell division and daughter cell numbers with inherited changes in methylation, but increased number of DEGs due to both toxicity and methylation changes. As usually observed in the literature, a small portion of DEGs (4% and 4% at 1 µM and 5 µM, respectively) are associated with DMRs in their promoters. These promoter DMRs by themselves are sufficient among other epigenetic marks to induce DEGs. The dataset provides the genomic coordinates of the DMRs and an opportunity to further examine their roles in distal putative promoters or enhancers (yet to be described in the SH) in contributing to gene expression changes, senescence bypass and sustained proliferation as essential carcinogenic events (see companion paper [1]). Finally, this experiment confirms the possibility in future experiments to use 5adC as a positive control for effects on DNA methylation in cells derived from SH.

Construction of a new chromosome-scale, long-read reference genome assembly for the Syrian hamster, Mesocricetus auratus.

BACKGROUND: The Syrian hamster (Mesocricetus auratus) has been suggested as a useful mammalian model for a variety of diseases and infections, including infection with respiratory viruses such as SARS-CoV-2. The MesAur1.0 genome assembly was generated in 2013 using whole-genome shotgun sequencing with short-read sequence data. Current more advanced sequencing technologies and assembly methods now permit the generation of near-complete genome assemblies with higher quality and greater continuity. FINDINGS: Here, we report an improved assembly of the M. auratus genome (BCM_Maur_2.0) using Oxford Nanopore Technologies long-read sequencing to produce a chromosome-scale assembly. The total length of the new assembly is 2.46 Gb, similar to the 2.50-Gb length of a previous assembly of this genome, MesAur1.0. BCM_Maur_2.0 exhibits significantly improved continuity, with a scaffold N50 that is 6.7 times greater than MesAur1.0. Furthermore, 21,616 protein-coding genes and 10,459 noncoding genes are annotated in BCM_Maur_2.0 compared to 20,495 protein-coding genes and 4,168 noncoding genes in MesAur1.0. This new assembly also improves the unresolved regions as measured by nucleotide ambiguities, where ∼17.11% of bases in MesAur1.0 were unresolved compared to BCM_Maur_2.0, in which the number of unresolved bases is reduced to 3.00%. CONCLUSIONS: Access to a more complete reference genome with improved accuracy and continuity will facilitate more detailed, comprehensive, and meaningful research results for a wide variety of future studies using Syrian hamsters as models.

Effect of Motility Factors D-Penicillamine, Hypotaurine and Epinephrine on the Performance of Spermatozoa from Five Hamster Species.

Assessments of sperm performance are valuable tools for the analysis of sperm fertilizing potential and to understand determinants of male fertility. Hamster species constitute important animal models because they produce sperm cells in high quantities and of high quality. Sexual selection over evolutionary time in these species seems to have resulted in the largest mammalian spermatozoa, and high swimming and bioenergetic performances. Earlier studies showed that golden hamster sperm requires motility factors such as D-penicillamine, hypotaurine and epinephrine (PHE) to sustain survival over time, but it is unknown how they affect swimming kinetics or ATP levels and if other hamster species also require them. The objective of the present study was to examine the effect of PHE on spermatozoa of five hamster species (Mesocricetus auratus, Cricetulus griseus, Phodopus campbelli, P. sungorus, P. roborovskii). In sperm incubated for up to 4 h without or with PHE, we assessed motility, viability, acrosome integrity, sperm velocity and trajectory, and ATP content. The results showed differences in the effect of PHE among species. They had a significant positive effect on the maintenance of sperm quality in M. auratus and C. griseus, whereas there was no consistent effect on spermatozoa of the Phodopus species. Differences between species may be the result of varying underlying regulatory mechanisms of sperm performance and may be important to understand how they relate to successful fertilization.

Therapeutic Efficacy of Arnica in Hamsters with Cutaneous Leishmaniasis Caused by Leishmania braziliensis and L. tropica.

Leishmaniasis may occur in three different clinical forms, namely, visceral, mucocutaneous and cutaneous, which are caused by different species of trypanosomatid protozoans of the genus Leishmania. Pentavalent antimonials are the leading treatment for cutaneous leishmaniasis despite the hepatic, renal, and cardiac toxicity. In addition, the response of some Leishmania species to pentavalent antimonials is increasingly poorer, and therefore new and more potent therapeutic alternatives are needed. Arnica montana L., Asteraceae, is a traditional medicinal plant of Europe and preparations of its flowers are commonly used externally to treat disorders of the musculoskeletal system as well as superficial inflammatory conditions. Previous studies have shown that Arnica tincture (AT), an ethanolic extract prepared from the flowerheads of Arnica montana as well as isolated Arnica sesquiterpene lactones (STLs) have antileishmanial activity in vitro against L. donovani and L. infantum, as well as in vivo against L. braziliensis. In this work, we studied the in vitro cytotoxicity and antileishmanial activity of AT and STLs against both L. braziliensis and L. tropica. The in vivo therapeutic effect of AT was studied in hamsters with cutaneous Leishmaniasis (CL) caused by experimental infection with L. braziliensis and L. tropica. Furthermore, various semisolid Arnica preparations were also evaluated against L. braziliensis. The STLs and the AT possess a very high in vitro activity against both Leishmania species with median effective concentrations (EC50) ranging from 1.9 to 5.9 µg/mL. The AT was not cytotoxic for human tissue macrophages, skin fibroblasts, and hepatic cells. The therapeutic response of hamsters infected with L. braziliensis to the topical treatment with AT was 87.5% at a dose of 19.2 µg STL/2× day/60 d, 72.7% at doses of 19.2 µg STL/1× d/60 d and 67% at a dose of 38.4 µg STL/2× d/60 d. In turn, the therapeutic response in hamsters infected with L. tropica was 100% when treated at a dose of 19.2 µg STL/2× day/60 d and 71% at a dose of 38.4 µg STL/2× d/60 d. On the other hand, the effectiveness of treatment with glucantime administered intralesionally at a dose of 200 mg/every three days for 30 days was 62.5% for L. braziliensis and 37.5% for L. tropica infection. These results are promising and encourage the implementation of clinical trials with AT in CL patients as a first step to using AT as a drug against CL.