Establishment of a secondary infection laboratory model of Echinococcus shiquicus metacestode using BALB/c mice and Mongolian jirds (Meriones unguiculatus).

Echinococcus shiquicus is peculiar to the Qinghai­Tibet plateau of China. Research on this parasite has mainly focused on epidemiological surveys and life cycle studies. So far, limited laboratory studies have been reported. Here, experimental infection of E. shiquicus metacestode in BALB/c mice and Mongolian jirds (Meriones unguiculatus) was carried out to establish alternative laboratory animal models. Intraperitoneal inoculation of metacestode material containing protoscoleces (PSCs) obtained from infected plateau pikas were conducted on BALB/c mice. Furthermore, metacestode material without PSCs deriving from infected BALB/c mice was intraperitoneally inoculated to Mongolian jirds. Experimental animals were dissected for macroscopic and histopathological examination. The growth of cysts in BALB/c mice was infiltrative, and they invaded the murine entire body. Most of the metacestode cysts were multicystic, but a few were unilocular. The cysts contained sterile vesicles, which had no PSCs. The metacestode materials were able to successfully infect new mice. In the jirds model, E. shiquicus cysts were typically formed freely in the peritoneal cavity; the majority of these cysts were free while a small portion adhered loosely to nearby organs. The proportion of fertile cysts was high, and contained many PSCs. The PSCs produced in Mongolian jirds also successfully infected new ones, which confirms that jirds can serve as an alternative experimental intermediate host. In conclusion, a laboratory animal infection was successfully established for E. shiquicus using BALB/c mice and Mongolian jirds. These results provide new models for the in-depth study of Echinococcus metacestode survival strategy, host interactions and immune escape mechanism.

Context dependence of head bobs in gerbils and potential neural contributions.

Headbobs are up-down movements of the cranium associated with the use of motion parallax for depth perception. Mongolian gerbils (aka jirds; Meriones unguiculatus) often execute a series of headbobs prior to jumping between surfaces. Gerbils were tested in a jumping stand task and headbobs videotaped under three light levels approximating low daylight, dawn/dusk, and moonlight across a range of distances to target. Headbobs per trial increased linearly with increasing distance to the target platform, whereas headbob frequency (rate of headbobbing pre-jump on the start platform) increased with gap distance up to an intermediate level and then decreased. Overall, gerbils made the most headbobs per trial under the darkest conditions, whereas their headbobbing rate was highest for medium illumination, especially for medium-long gap distances. There was a positive correlation between headbob frequency and volume of the superior colliculus (SC), but no relationship between headbobs and relative size of the temporo-posterior (TP) visual cortex. The results suggest that gerbils employ a specific visuomotor strategy for depth perception differentially under different conditions. We suggest that the deployment of headbobs under specific conditions may be part of an SC-driven vigilant state, of which more rapid sampling of the visual environment using headbobs for depth estimation is one component. Moreover, the findings highlight the importance of considering ecological factors in designing studies of visual behavior and its underpinnings in rodents.

Automatic barcode gap discovery reveals diverse clades of Rhipicephalus spp. and Haemaphysalis spp. ticks from small mammals in 'Asir, Saudi Arabia.

BACKGROUND: The ixodid tick genera Rhipicephalus and Haemaphysalis contain several species of medical and/or veterinary importance, but their diversity in some regions of the world remains under-explored. For instance, very few modern studies have been performed on the taxonomy of these genera on the Arabian Peninsula. METHODS: In this study, we trapped small mammals in the 'Asir Mountains of south-western Saudi Arabia and collected tick specimens for morphological examination and molecular barcoding, targeting three mitochondrial loci: cox1, 16S rRNA and 12S rRNA. RESULTS: We obtained a total of 733 ticks (608 Haemaphysalis spp. and 125 Rhipicephalus spp.) from 75 small mammal hosts belonging to six species. All tick specimens were immature except for nine adults recovered from a hedgehog (Paraechinus aethiopicus). Morphologically, the Rhipicephalus ticks resembled R. camicasi, but the Haemaphysalis ticks showed differences in palp morphology compared with species previously described from Saudi Arabia. Phylogenetic analysis and automatic barcode gap discovery identified a novel clade of Rhipicephalus sp. representing most of the nymphs. This was most closely related to R. leporis, R. guilhoni and R. linnaei. The adult ticks and a small proportion of nymphs clustered with R. camicasi sequences from a previous study. Finally, the Haemaphysalis nymphs formed two distinct clades that were clearly separated from all reference sequences but closest to some African species. CONCLUSIONS: This apparent high level of tick diversity observed in a single study site of only ~ 170 km2, on a relatively small number of hosts, highlights the potential for the discovery of new tick species on the Arabian Peninsula.

A rapid, parasite-dependent cellular response to Dirofilaria immitis in the Mongolian jird (Meriones unguiculatus).

BACKGROUND: The Mongolian jird (Meriones unguiculatus) has long been recognized as a permissive host for the filarial parasite Brugia malayi; however, it is nonpermissive to another filarial parasite, canine heartworm (Dirofilaria immitis). By elucidating differences in the early response to infection, we sought to identify mechanisms involved in the species-specific clearance of these parasites. We hypothesized that the early clearance of D. immitis in intraperitoneal infection of the jird is immune mediated and parasite species dependent. METHODS: Jird peritoneal exudate cells (PECs) were isolated and their attachment to parasite larvae assessed in vitro under various conditions: D. immitis and B. malayi cultured separately, co-culture of both parasites, incubation before addition of cells, culture of heat-killed parasites, and culture with PECs isolated from jirds with mature B. malayi infection. The cells attaching to larvae were identified by immunohistochemistry. RESULTS: In vitro cell attachment to live D. immitis was high (mean = 99.6%) while much lower for B. malayi (mean = 5.56%). This species-specific attachment was also observed when both filarial species were co-cultured, with no significant change from controls (U(9, 14) = 58.5, p = 0.999). When we replicated these experiments with PECs derived from jirds subcutaneously infected with B. malayi, the results were similar (99.4% and 4.72% of D. immitis and B. malayi, respectively, exhibited cell attachment). Heat-killing the parasites significantly reduced cell attachment to D. immitis (mean = 71.9%; U(11, 14) = 7.5, p < 0.001) while increasing attachment to B. malayi (mean = 16.7%; U(9, 15) = 20, p = 0.002). Cell attachment to both species was reduced when larvae were allowed a 24-h pre-incubation period prior to the addition of cells. The attaching cells were identified as macrophages by immunohistochemistry. CONCLUSIONS: These results suggest a strongly species-dependent response from which B. malayi could not confer protection by proxy in co-culture. The changes in cell attachment following heat-killing and pre-incubation suggest a role for excretory/secretory products in host immune evasion and/or antigenicity. The nature of this attachment is the subject of ongoing study and may provide insight into filarial host specificity.

Assessment of Testicular Lhcgr mRNA Expression Correlated with Testis and Seminal Vesicle Activities in the Libyan jird (Meriones libycus, Rodentia: Muridae) during Breeding Season Compared with Nonbreeding Season.

The Libyan jird (Meriones libycus, 1823) is a wild desert rodent that is a seasonal breeder species adapted to breed when the environmental conditions can satisfy the energy and hydrous requirements of pregnant and nursing females to ensure that births occur at the most favorable time of the year. We assessed gene expression of testicular luteinizing hormone receptor (Lhcgr) correlated to testis activity. The expression of Lhcgr was evaluated using quantitative Real Time-Polymerase Chain Reaction (qRT-PCR and the testis activity by a histological method in adult male Libyan jirds during the nonbreeding and breeding seasons. Our results showed that Lhcgr mRNA expression increased in autumn during the nonbreeding season and decreased in spring during the breeding season. This expression varied in contrast to testicular structure or function and plasma testosterone levels. These results help to elucidate this desert rodent's seasonal sexual activity, which is correlated with central regulation.

Development of Acanthocheilonema viteae in Meriones shawi: Absence of microfilariae and production of active ES-62.

AIMS: ES-62 is a well-studied anti-inflammatory molecule secreted by L4-adult stage Acanthocheilonema viteae. We maintain the life cycle of A viteae using Meriones libycus as the definitive host. Here, we investigated whether the full life cycle could be maintained, and functional ES-62 produced, in a related jird species-Meriones shawi. METHODS AND RESULTS: Adult worms were produced in comparable numbers in the two species, but very few microfilariae (MF) were observed in the M shawi bloodstream. M shawi ES-62 produced ex vivo was functional and protective in a mouse model of arthritis. Myeloid-derived cells from naïve and infected jirds of both species were compared with respect to ROS production and osteoclast generation, and some differences between the two species in both the absence and presence of infection were observed. CONCLUSIONS: The life cycle of A viteae cannot be successfully completed in M shawi jirds but L3 stage worms develop to adulthood and produce functional ES-62. Preliminary investigation into jird immune responses suggests that infection can differentially modulate myeloid responses in the two species. However, species-specific reagents are required to understand the complex interplay between A viteae and its host and to explain the lack of circulating MF in infected M shawi jirds.

Stone quarrying induces organ dysfunction and oxidative stress in Meriones libycus.

Exposure to heavy metal-containing dust arising from stone quarrying may cause severe health problems. The aim of this study was to evaluate the impact of stone quarrying in Riyadh (Saudi Arabia) on the Libyan jird Meriones libycus. Soil samples and jirds were collected from four sites located at different distances from the quarrying area. Soil from the first (500 m away from the quarry) and second (1800 m away) sites showed a significant increase in cadmium (Cd), lead (Pb), nickel (Ni), and vanadium (V) when compared with the reference site (38,000 m away). Jirds at these sites exhibited significant increases in liver, kidney, lung, and fur levels of Cd, Pb, Ni, and V. Serum transaminases, creatinine, and malondialdehyde (MDA) levels were significantly increased in jirds, whereas reduced glutathione (GSH) levels decreased. Liver, kidney, and lung tissues of jirds, collected from the first and second sites, showed significantly increased MDA and decreased GSH levels. Additionally, animals at both sites showed altered hematological parameters and several histopathological changes in their liver, kidney, and lung. Soil and animals at the third site (7300 m away) showed no significant changes. Thus, our study showed the impact and hazardous effects of quarrying on the liver, kidney, lung, and hemogram of M. libycus. These findings can provide scientific evaluation for studying the impact of quarrying on the workers and communities living close to the studied area.

Lipid profiling of the filarial nematodes Onchocerca volvulus, Onchocerca ochengi and Litomosoides sigmodontis reveals the accumulation of nematode-specific ether phospholipids in the host.

Onchocerciasis, a neglected tropical disease prevalent in western and central Africa, is a major health problem and has been targeted for elimination. The causative agent for this disease is the human parasite Onchocerca volvulus. Onchocerca ochengi and Litomosoides sigmodontis, infectious agents of cattle and rodents, respectively, serve as model organisms to study filarial nematode infections. Biomarkers to determine infection without the use of painful skin biopsies and microscopic identification of larval worms are needed and their discovery is facilitated by an improved knowledge of parasite-specific metabolites. In addition to proteins and nucleic acids, lipids may be suitable candidates for filarial biomarkers that are currently underexplored. To fill this gap, we present the phospholipid profile of the filarial nematodes O. ochengi, O. volvulus and L. sigmodontis. Direct infusion quadrupole time-of-flight (Q-TOF) mass spectrometry was employed to analyze the composition of phospholipids and their molecular species in the three nematode species. Analysis of the phospholipid profiles of plasma or serum of uninfected and infected hosts showed that nematode-specific phospholipids were below detection limits. However, several phospholipids, in particular ether lipids of phosphatidylethanolamine (PE), were abundant in O. ochengi worms and in bovine nodule fluid, suggesting that these phospholipids might be released from O. ochengi into the host, and could serve as potential biomarkers.

The complete mitochondrial genome of the Tamarisk gerbil, Meriones tamariscinus (Rodentia: Muridae).

The complete mitochondrial genome of the Tamarisk jird, Meriones tamariscinus, was sequenced. The 16,389bp genome contains 37 genes, typical for rodent mitogenomes, including 22 tRNA genes, 2 rRNA genes, and 13 protein-coding genes. The total GC content of the mitochondrial genome is 36.8%, with a base composition of 34.0% A, 24.5% C, 12.3% G, and 29.2% T. The phylogenetic analysis showed that M. tamariscinus was classified in the genus Meriones, Muridae.

Haemonchus contortus: Applications in Drug Discovery.

Haemonchus contortus is an important pathogen of small ruminants and is therefore a crucially important target for anthelmintic chemotherapy. Its large size and fecundity have been exploited for the development of in vitro screens for anthelmintic discovery that employ larval and adult stages in several formats. The ability of the parasite to develop to the young adult stage in Mongolian jirds (Meriones unguiculatus) provides a useful small animal model that can be used to screen compounds prior to their evaluation in infected sheep. This chapter summarizes the use of H. contortus for anthelmintic discovery, offers a perspective on current strategies in this area and suggests research challenges that could lead to improvements in the anthelmintic discovery process.

Accumulation of heavy metals and As in liver, hair, femur, and lung of Persian jird (Meriones persicus) in Darreh Zereshk copper mine, Iran.

Rodents frequently serve as bioindicator to monitor the quality of the environment. Concentrations of 11 elements (Cd, Co, Ti, Fe, Mn, Cu, Sb, As, Sr, Ni, and Cr) were investigated and compared in liver, hair, femur, and lung of the Persian jird (Meriones persicus) from Darreh Zereshk copper mine, Iran. Metals were determined in different tissues of 39 individuals of Persian jird, collected by snap trap in 2014 from five areas of Darreh Zereshk copper mine. Samples were prepared by wet digestion method, and the contents of elements were analyzed with ICP-OES (VARIAN, 725-ES) instrument. Cadmium, Sb, and Co were below the limit of detection, and Mn and As were found only in hair and liver tissues. We detected the highest concentration of Cu, As, Ti, Fe, Mn, Cr, and Ni in hair in comparison with other tissues. Significant higher levels of Ti in femur and hair; Fe in liver and hair; Mn in liver; As in hair; Sr in lung; Cr in lung, hair, femur, and liver; Cu in femur; and Ni in liver and lung tissues were observed in females. Nearly all element concentrations in the tissues of Persian jird from flotation site, Darreh Zereshk and Hasan Abad villages and leaching site (mining areas) were higher than those from tailing dump site (reference site). We found the highest concentrations of As in liver and hair; Ni and Cr in liver, hair, and lung; and Sr in lung and hair tissues of Persian jird in leaching site. We tried to specify the status of elements before fully exploitation of Darreh Zereshk copper mine by using bioindicator species. Based on our achievements, initial activities did not strongly pollute the surrounded environment of the mine. The high abundance of Persian jird as well as their several proper features makes them a suitable species for biomonitoring programs especially for further studies will be performed after full exploitation of Darreh Zereshk copper mine.

Synthesis and biological evaluation of 4-oxycoumarin derivatives as a new class of antifilarial agents.

A series of 4-oxycoumarin derivatives was synthesized, characterized and evaluated in vitro and in vivo for antifilarial activity against the human lymphatic filarial parasite, Brugia malayi. A majority of the compounds studied showed potent in vitro activity with low IC50 values in the micro molar (µM) range (0.014-1.73 and 0.0056-0.43) against adult worms and microfilariae, respectively. Compounds 8 and 9 were identified to be the most promising antifilarial candidate molecules exhibiting activity in the nanomolar (nM) range. The IC50 values for compound 8 were 14 nM and 5.6 nM while for compound 9 were 94 nM and 13 nM, respectively, for adult worm and microfilaria. These two compounds also displayed promising adulticidal activity (74.9 ± 4.8% and 69.4 ± 2.8%, respectively) in the primary rodent (jird) screen. This study also serves as a starting point for investigating structure-activity relationship with different amino substituents.

Transient-state mechanisms of wind-induced burrow ventilation.

Burrows are common animal habitations, yet living in a burrow presents physiological challenges for its inhabitants because the burrow isolates them from sources and sinks for oxygen, carbon dioxide, water vapor and ammonia. Conventionally, the isolation is thought to be overcome by either diffusion gas exchange within the burrow or some means of capturing wind energy to power steady or quasi-steady bulk flows of air through it. Both are examples of what may be called 'DC' models, namely steady to quasi-steady flows powered by steady to quasi-steady winds. Natural winds, however, are neither steady nor quasi-steady, but are turbulent, with a considerable portion of the energy contained in so-called 'AC' (i.e. unsteady) components, where wind velocity varies chaotically and energy to power gas exchange is stored in some form. Existing DC models of burrow gas exchange do not account for this potentially significant source of energy for ventilation. We present evidence that at least two AC mechanisms operate to ventilate both single-opening burrows (of the Cape skink, Trachylepis capensis) and double-opening model burrows (of Sundevall's jird, Meriones crassus). We propose that consideration of the physiological ecology and evolution of the burrowing habit has been blinkered by the long neglect of AC ventilation.

Ventilation of multi-entranced rodent burrows by boundary layer eddies.

Rodent burrows are often assumed to be environments wherein the air has a high concentration of CO2. Although high burrow [CO2] has been recorded, many studies report burrow [CO2] that differs only slightly from atmospheric concentrations. Here, we advocate that one of the reasons for these differences is the penetration into burrows of air gusts (eddies), which originate in the turbulent boundary layer and prevent build-up of CO2. We have characterized the means by which burrows of Sundevall's jird, which are representative of the burrows of many rodent species with more than one entrance, are ventilated. Our results demonstrate that, even at low wind speeds, the random penetration of eddies into a burrow through its openings is sufficient to keep the burrow [CO2] low enough to be physiologically inconsequential, even in its deep and remote parts.

THE RESPONSE OF SPECIFIC ANTIBODIES IN SERUM OF JIRDS AND MICE AFTER INFECTION OF PERIODIC BRUGIA MALAYI / 第二军医大学学报

This paper deals with the regularity of the changes in 'serum specific IgM and IgG, and the relationship between the antibody level and infected worm stage of Brugia malayi.The jirds (Meriones unguiculatus) and BALB/cCR mice infected with three different methods were used in the experiment.The antibody level in BALB/cCR mice after infection was higher than that in jirds.The occurrence of IgM in infected jirds and mice was earlier than that of IgG,reached its peak at 4-8th week, and maintained a certain level during 30 weeks.The responses of IgM and IgG were considered as an immunological characteristic of parasitic helminth infection probably.