Development of a new cerebral ischemia reperfusion model of Mongolian gerbils and standardized evaluation system

Background:The Mongolian gerbil is an excellent laboratory animal for preparing the cerebral ischemia model due to its inherent deficiency in the circle of Willis.However,the low incidence and unpredictability of symptoms are caused by numerous complex variant types of the circle.Additionally,the lack of an evaluation system for the cer-ebral ischemia/reperfusion(I/R)model of gerbils has shackled the application of this model.Methods:We created a symptom-oriented principle and detailed neurobehavioral scoring criteria.At different time points of reperfusion,we analyzed the alteration in locomotion by rotarod test and grip force score,infarct volume by triphenyltetrazo-lium chloride(TTC)staining,neuron loss using Nissl staining,and histological charac-teristics using hematoxylin-eosin(H&E)straining.Results:With a successful model rate of 56%,32 of the 57 gerbils operated by our method harbored typical features of cerebral I/R injury,and the mortality rate in the male gerbils was significantly higher than that in the female gerbils.The suc-cessfully prepared I/R gerbils demonstrated a significant reduction in motility and grip strength at 1 day after reperfusion;formed obvious infarction;exhibited typi-cal pathological features,such as tissue edema,neuronal atrophy and death,and vacuolated structures;and were partially recovered with the extension of reperfu-sion time.Conclusion:This study developed a new method for the unilateral common carotid artery ligation I/R model of gerbil and established a standardized evaluation system for this model,which could provide a new cerebral I/R model of gerbils with more practical applications.

The effect of mast cell on the induction of Helicobacter pylori infection in Mongolian gerbils

INTRODUCTION Since 1982,Helicobacter pylori(Hp) has been successfully isolated and cultured,and the fact many diseases such as gastritis,peptic ulcer,gastric carcinoma

Experimental infection of Z:ZCLA Mongolian gerbils with human hepatitis E virus

AIM:To investigate whether Z:ZCLA Mongolian gerbils are readily susceptible to infection by human hepatitis E virus(HEV).METHODS:Z:ZCLA Mongolian gerbils were infected with a clinical HEV strain isolated from an acutehepati tis E patient,and virus pathogenesis was assessed in this host.Non-infected gerbils served as the control group.Feces samples from gerbils were collected weekly for reverse transcription-nested polymerase chain reaction.Serum anti-HEV Ig G and alanine aminotransferase(ALT) were detected by enzyme linked immunosorbent assay.At sacrifice,each animal's liver,spleen and kidney were collected for histopathologic examination.RESULTS:HEV-infected gerbils showed fatigue,with histopathological changes observed in the liver,spleen and kidney.HEV RNA was detected in fecal samples taken at day 7 after inoculation and the detectable levels lasted out to day 42 after inoculation.Interestingly,ALT levels were only moderately increased in the HEV-infected animals compared with the noninfected control group.CONCLUSION:Z:ZCLA Mongolian gerbils are susceptible to human HEV.

Time-course pattern of neuronal loss and gliosis in gerbil hippocampi following mild, severe, or lethal transient global cerebral ischemia

Transient ischemia in the whole brain leads to neuronal loss/death in vulnerable brain regions. The striatum, neocortex and hippocampus selectively loose specific neurons after transient ischemia. Just 5 minutes of transient ischemia can cause pyramidal neuronal death in the hippocampal cornu ammonis (CA) 1 field at 4 days after transient ischemia. In this study, we investigated the effects of 5-minute (mild), 15-minute (severe), and 20-minute (lethal) transient ischemia by bilateral common carotid artery occlusion (BCCAO) on behavioral change and neuronal death and gliosis (astrocytosis and microgliosis) in gerbil hippocampal subregions (CA1-3 region and dentate gyrus). We performed spontaneous motor activity test to evaluate gerbil locomotor activity, cresyl violet staining to detect cellular distribution, neuronal nuclei immunohistochemistry to detect neuronal distribution, and Fluoro-Jade B histofluorescence to evaluate neuronal death. We also conducted immunohistochemical staining for glial fibrillary acidic protein and ionized calcium-binding adapter molecule 1 (Ibal) to evaluate astrocytosis and microgliosis, respectively. Animals subjected to 20-minute BCCAO died in at least 2 days. BCCAO for 15 minutes led to pyramidal cell death in hippocampal CA1-3 region 2 days later and granule cell death in hippocampal de匚tate gyrus 5 days later. Similar results were not found in animals subjected to 5-minute BCCAO. Gliosis was much more rapidly and severely progressed in animals subjected to 15-minute BCCAO than in those subjected to 5- minute BCCAO. Our results indicate that neuronal loss in the hippocampal formation following transient ischemia is significantly different according to regions and severity of transient ischemia. The experimental protocol was approved by Institutional Animal Care and Use Committee (AICUC) of Kangwon National University (approval No. KW-180124-1) on May 22, 2018.

Geographical distribution and ecological features of the great gerbil subspecies in the main zoonotic cutaneous leishmaniasis foci in Iran

Objective:To reveal subspecies composition of Rhombomy opimus(R.opimus) in Iran. Methods:In this study,field specimens of the gerbil were collected from all its geographical rang in northeast and central parts of Iran and identified on basis of morphological characteristics.Results:Results revealed presence of two subspecies of R.opimus sodalis and R. opimus sargadensis in the country.The first subspecies with brown to hazel-nut color and a size bigger than a typical R.opimus was found only in Golestan province,an isolated colony which is located in plains of north slopes of Alborz Chain Mountains of the country,connected with the Turkmenistan.The subspecies of R.opimus sargadensis with a yellowish color and similar size as a typical R.opimus was found in all other areas of the great gerbil distribution in Iran.There was a distinct topographic difference but similar ectoparasites between colonies of the two subspecies in the study area.Conclusions:Further ecological and genetic investigations are required for more detailed description of the R.opimus subspecies range and structure.The R.opimusPhlebotomus papatasi-Leishmania major association and the ZCL severity and outcome in hosts are discussed.

Effects of adaptation to handling on the circadian rhythmicity of blood solutes in Mongolian gerbils

The Mongolian gerbil has been widely used in many research fields and has been reported to be a diurnal laboratory animal. The circadian rhythmicity of these gerbils was investigated in the present study by measuring two hormones that show daily oscillations, cortisol and ACTH, in serum using ELISA kits. The levels of the two hormones were highest at 8:00 am and their rhythmic changes were similar to those in humans. In addition, the influence of stress of handling and blood collection on the physiological parameters of the gerbils was examined. After adaptation to handling for 1 week, some serum parameters in the animals changed. Handling and blood collection did not impact significantly on the following parameters: creatine kinase (CK), lactate dehydrogenase (LD), alanine aminotransferase (ALT), aspartate transaminase (AST), blood urea nitrogen (BUN), and albumin (ALB). However, blood glucose (GLU), total protein (TP) and globulin (GLB) significantly increased while creatinine (CRE) and albumin/globulin (A/G) significantly decreased after adaptation. This work further confirms that the Mongolian gerbil is a diurnal animal and also indicates that a suitable adaptation procedure is necessary for getting reliable results when performing experiments using these animals.

ECO-ETHOLOGY OF POPULATION REGULATION AMONG GERBILS IN THE SAHARAN ENVIRONMENT Study of the dynamics of populations,of their demographic impetus their food strategies and their reproduction strategies among four species of gerbil in Morocco.(Meriones sha

The following study of populations of gerbil in arid and Saharan terrain enables us toexamine the relationships between the essential determinants in the cycles of abundance. Social unity, methods of spatial distribution, dispersal, strategies for food and repro-duction, and also disappearance, are linked to climatic factors and defined according to therecognised hierarchy of stages of perceptions in Ecology individual, group, population,

Effect of L-Deprenyl on the Putrescine Level and Neuronal Damage after Transient Global Cerebral Ischemia in Gerbils

L-Deprenyl is selective and irreversible monoamine oxidase B inhibitor, known to have neuroprotective properties. Putrescine, one of polyamine, is thought to be important in the neuronal cell damage associated with various type of excitatory neurotoxicity. We examined the effects of L-deprenyl on the changes in putrescine level and neuronal damage after transient global ischemia in ger-bils. Male Mongolian gerbils weighing 65 - 75 g were used in the experiment. Global ischemia was induced by occlusion of common carotid arteries for 3 min to observe neuronal injury in hippocampal pyramidal cells. L-Deprenyl group was given 10 mg/kg of L-deprenyl intraperitoneally immediately after, 3 h and 6 h after global ischemia. Treated animals were processed in parallel with ischemic animals receiving saline as a vehicle and with sham- operated controls. Hippocampal putrescine level was increased by global ischemia and inhibited by L-deprenyl treatment. In histological findings, counts of viable neurons were made in the pyramidal cell layer of the hippocampal CA1 area 3 days after ischemic insult. The number of viable neurons in the pyramidal cell layer of CA1 area was significantly increased in animals treated with L-deprenyl compared to vehicle-treated ischemic animals (p < 0.05). In terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick endlabeling (TUNEL) assay, semiquantitative analysis of dark-brown neuronal cells was made in the hippocampal CA1 area. There was also a significant difference in the degree of TUNEL staining in the hippocampal CA1 area between vehi-cle-treated and L-deprenyl-treated animals (p < 0.05). These data show L-deprenyl is effective as a prophylactic treatment for neuronal injury when it is administrated before ischemia but a further study need to know the effects of administration of L-deprenyl after ischemia and at given times after reper-fusion.

Evaluation of an ischemic model in ischemia prone and general Mongolian gerbils by neurological symptom, injury,and sex difference

Background: In the previous study, we established an ischemia-prone gerbil population(IG), which was selectively bred to increase the incidence of unilateral carotid arterial occlusion(UCO)-induced ischemia in Mongolian gerbils. However, if the characteristics of ischemia model in IG are the same as those in general gerbils(GG), and if the neurological symptoms are associated with the neurological insults in IG is still unclear.Methods: In the present study, we evaluated the UCO model in IG by analyzing neurological symptoms, neurological injury in the hippocampal CA1 region and compared with GG.Results: The data showed that the ratios of neurological symptom scores ≥ 2 in the IG and GG groups were 65.0% vs 30.0%, respectively, and were significantly different(P <.01).The neuronal damage following a UCO ischemic insult in the IG group was more severe compared to the GG group. There was a high correlation between the neurological insults' scale and the neurological symptom score in the IG and GG groups(r =.979 and.943 in the IG and GG groups, respectively). In animals with mild neurological symptom scores(2 and 3), the neuronal insults were significantly different between female and male gerbils in both IG and GG.Conclusion: Our findings suggest that IG population would likely be more advantageous to establish an ischemic model.

Tyrosinase (Tyr) Gene Mutation in Albino Mongolian Gerbil (Meriones unguiculatus)

Tyrosinase is encoded by the Tyr (c or albino) locus and is the key enzyme in pigment biosynthesis. Loss of function of this enzyme caused by gene mutation results in albinism. Most cases of albinism are caused by missense mutations of tyrosinase. Albino mutations in Tyr have been identified in various animals, including human, mouse, rat, rabbit, cattle, cat, and ferret, but not in gerbil. We created two new gerbil strains: MON/Num/a (inbred agouti phenotype) and MON/Num/c (albino phenotype). Here, we report that four nucleotide substitutions in the Tyr gene caused two missense mutations in amino acids in the albino gerbil: a G-to-A mutation at position 204 in exon 1 caused R77H, and A-to-G at position 1392 and G-to-T at position 1393 in exon 5 caused Q473R. The substitution at position 1408 in exon 5 was silent. These missense mutations are conserved in all albino phenotypes we tested. Therefore, we suggest that these mutations are responsible for albinism in gerbil.

H pylori infection causes chronic pancreatitis in Mongolian gerbils

AIM: To investigate whether chronic H pylori infection has the potential to induce pancreatitis in the Mongolian gerbil model, and whether it is dependent on an intact type Ⅳ secretion system. METHODS: Mongolian gerbils were infected with wild type (WT) H pylori typeⅠstrain B128 or its isogenic mutant B128 ?cagY (defective type Ⅳ secretion). After seven months of infection, H pylori was reisolated from antrum and corpus and H pylori DNA was analyzed by semi- nested polymerase chain reaction (PCR). Inflammation and histological changes were documented in the gastric antrum, corpus, and pancreas by immunohistochemistry. Cytokine mRNA, gastric pH, plasma gastrin, amylase, lipase, and glucose levels were determined. RESULTS: The H pylori infection rate was 95%. Eight infected animals, but none of the uninfected group, developed transmural inflammation and chronic pancreatitis. Extensive interstitial fibrosis and inflammation of the pancreatic lobe adjacent to the antrum was confirmed by trichrome stain, and immuno- histochemically. Pro-inflammatory cytokine mRNA was significantly increased in the antral mucosa of all infected gerbils. In the corpus, only cytokine levels of WT-infected animals and those developing transmural inflammation and pancreatitis were significantly increased. Levels of lipase, but not glucose or amylase levels, were significantly reduced in the pancreatitis group. H pylori DNA was detected in infected antral and corpus tissue,but not in the pancreas. CONCLUSION: H pylori infection is able to induce chronic pancreatitis in Mongolian gerbils independently of the type Ⅳ secretion system, probably by an indirect mechanism associated with a penetrating ulcer.

Short-term Celecoxib intervention is a safe and effective chemopreventive for gastric carcinogenesis based on a Mongolian gerbil model

AIM:To evaluate the optimal intervention point of a selective cyclooxygenase-2(COX-2) inhibitor,Celecoxib,for inhibiting Helicobacter pylori(H pylori)-associated gastric carcinogenesis in Mongolian gerbils(MGs).METHODS:One hundred and twelve MGs were divided into six groups(A-F).One hundred gerbils were inoculated with H pylori(groups A-E).Twelve gerbils were inoculated with vehicle broth only(group F).After 4 wk,they were given N'-methyl-N' -nitro-N-nitroso-guanidine(MNNG)(50 μg/mL) in the drinking water for 20 wk.In groups B-E,the animals were given the stock Celecoxib(10 mg/kg per day) diet from the 21st,31st,21st and 41st week respectively.The periods of administering Celecoxib were 30,20,20,and 15 wk respectively.On the 51st week,the animals were sacrificed for histological examination.Local PCNA expression was examined by the immunohistochemistry method.The expression of COX-2 protein was assessed by Western Blot.Analysis used the χ2 test.The difference was regarded as signifi cant when P value was less than 0.05.RESULTS:Seventeen percent(17/100) of H pylori-infected MGs developed gastric cancer.All of these lesions were well-differentiated adenocarcinoma.The incidence rates of adenocarcinoma in groups A-F were 40%,0%,0%,20%,25%,and 0% respectively.The inflammatory scores were higher in group B than in other groups.There was no inflammatory response noted in group F.Celecoxib treatment resulted in a significant reduction in the proliferation of H pylori-infected mucosal cells(groups B,C and D)(P < 0.01).The expression of COX-2 protein was significantly attenuated in the groups which were Celecoxib-treated for more than 20 wk(groups B,C,D).The groups treated with Celecoxib had a significantly lower rate of advanced gastric cancer(34% vs 75%,P<0.001) There were no sudden deaths in any of the groups.CONCLUSION:Short-term treatment with Celecoxib has an anti-carcinogenic effect,and resulted in less severe inflammation and inhibited the invasive degree of gastric cancer.

Anti-Helicobacter pylori therapy significantly reduces Helicobacter py/ori-Induced gastric mucosal damage in Mongolian gerbils

AIM: To investigate the effectiveness of 4 d' anti-Helicobacter pyloritherapy on the H pylori-infected Mongolian gerbils based on physiological and pathological changes.METHODS: We used 6-wk-old male gerbils orally inoculated with H pylori (ATCC43504, 2x108 CFU/mL).Seven weeks after H pylori inoculation, the animals of study group received 4 d' anti-H pylori triple therapy (H pylorieradicated group). Seven days later, all animals of the H pylori-eradicated and control groups (H pylori-infected& H pylori-uninfected groups) were sacrificed. We examined gastric mucosal lesions macroscopically, studied gastritis microscopically and determined the stomach weight ratio, myeloperoxidase (MPO) activity and prostaglandin (PG) E2 level.RESULTS: The results showed that both macroscopic and histological gastric damages were significantly less in H pylori-eradicated group than H pylori-infected group.Stomach weight ratio, MPO activity and PGE2 levels were significantly higher in H pylori-infected group than those in the other two groups.CONCLUSION: Four days' anti-H pylori therapy was effective in the improvement of H pylori-induced gastric lesions in Mongolian gerbils.

Helicobacter pyloristrain-specific modulation of gastric inflammation in Mongolian gerbils

AIM: The cag pathogenicity island (PAI) is one of potential virulence determinants of Helicobacter pylori. The Mongolian gerbil is a suitable experimental animal for the screening of virulence factors of H pylori.METHODS: Five-week-old Mongolian gerbils were inoculated with a standard H pylori strain (ATCC 43504)possessing the cag PAI or a clinical isolate lacking the genes' cluster (OHPC-0002). The animals were killed at 2, 4, 8, 24 and 48 wk after inoculation (n = 5 each), and macroscopic and histopathological findings in the stomachs were compared.RESULTS: In gerbils infected with ATCC 43504, a more severe degree of infiltration of polynuclear and mononuclear cells and lymphoid follicles was observed from 4 wk after inoculation compared to gerbils infected with OHPC-0002 especially in the antrum and transitional zone from the fundic to pyloric gland area. In addition,glandular atrophy, intestinal metaplasia, gastric ulcer and hyperplastic polyps were noted in gerbils infected with ATCC 43504, whereas only mild gastric erosions occurred in those infected with OHPC-0002.CONCLUSION: Our results indicate that the cag PAI could be directly involved in gastric immune and inflammatory responses in the Mongolian gerbils, leading to a more advanced gastric disease.

INDUCTION OF GASTRIC INTRAEPITHELIAL NEOPLASIA OF GLANDULAR STOMACH OF MONGOLIAN GERBILS BY ELICOBACTER PYLORI

Objective: To setup an animal model of gastric carcinogenesis by Helicobacter pylori (Hp) for basic, prevention and therapeutic research of Hp-related diseases. Methods: 22 young male Mongolian gerbils were administrated with suspension of Hp strain TN2 by intragastric gavage for 5 consecutive times (4×108 CFU/time, 1 time/4 days). 10 male gerbils were used as negative control. Two infected gerbils were killed at 10, 20, and 30 weeks, respectively, after inoculation to monitor the development of gastric lesions. Other animals were killed at 40 experimental weeks. Pathological changes of glandular stomach were examined histologically. Results: Gastric intraepithelial neoplasias (GIN) and low-grade dysplasias were observed only in the pyloric antrum of Hp-treated gerbils (3 and 2 ones, respectively), but not in control group (5/13 vs. 0/10, P<0.04). High incidence of chronic active gastritis and chronic atrophic gastritis were observed in Hp-treated animals (10/13, 76.9%). Low incidence of chronic atrophic gastritis was also detected in negative control gerbils (3/10, 30%; P<0.04). Conclusion: Hp inoculation could induce chronic inflammation and malignant lesions of the glandular stomach of Mongolian gerbils conveniently.

Estrogen and progesterone receptor isoforms expression in the stomach of Mongolian gerbils

AIM: We studied the estrogen receptor (ER) and progesterone receptor (PR) isoforms expression in gastric antrum and corpus of female gerbils and their regulation by estradiol (E2) and progesterone (P4). METHODS: Ovariectomized adult female gerbils were subcutaneously treated with E2, and E2 + P4. Uteri and stomachs were removed, the latter were cut along the greater curvature, and antrum and corpus were excised. Proteins were immunoblotted using antibodies that recognize ER-alpha, ER-beta, and PR-A and PR-B receptor isoforms. Tissues from rats treated in the same way were used as controls. RESULTS: Specific bands were detected for ER-alpha (68 KDa), and PR isoforms (85 and 120 KDa for PR-A and PR-B isoforms, respectively) in uteri, gastric antrum and corpus. We could not detect ER-beta isoform. PR isoforms were not regulated by E2 or P4 in uterus and gastric tissues of gerbils. ER-alpha isoform content was significantly down-regulated by E2 in the corpus, but not affected by hormones in uterus and gastric antrum. CONCLUSION: The presence of ER-alpha and PR isoforms in gerbils stomach suggests that E2 and P4 actions in this organ are in part mediated by their nuclear receptors.

长爪沙鼠不同感音神经性耳聋模型的建立及比较

目的利用不同的耳毒性药物建立长爪沙鼠感音神经性耳聋模型,并对3种模型进行比较分析,为感音神经性耳聋的研究提供精准的动物模型。方法选择长爪沙鼠,建立硫酸卡那霉素和呋塞米联用(KM+Fur)、新霉素(Neo)及哇巴因(Oua)3种耳毒性药物的感音神经性耳聋模型,通过听性脑干反应(ABR)和耳蜗组织形态学检测,比较分析不同耳毒性药物的损伤特点。结果KM+Fur造模后,与对照组(14.00±1.80)相比,该组(71.00±5.26)长爪沙鼠的听力阈值显著上升,耳蜗HCs大量损伤,而SGNs无明显损伤;Neo造模后,与对照组相比,40 mmol·L^(-1) Neo仅影响沙鼠高频32 kHz时听力阈值(60.00±8.66),无明显的组织学改变;而100 mmol·L^(-1) Neo组的沙鼠各频率听力阈值均显著上升,且耳蜗HCs及SGNs均严重受损;Oua造模后,1 mmol·L^(-1) Oua和10 mmol·L^(-1) Oua均可引起沙鼠各频率听力阈值显著上升,但损伤范围不同,10 mmol·L^(-1) Oua使HCs和SGNs均严重受损,而1 mmol·L^(-1) Oua仅造成耳蜗SGNs损伤。结论利用KM+Fur可建立长爪沙鼠HCs特异性受损的感音神经性耳聋模型;40 mmol·L^(-1) Neo可建立高频区听功能损伤的感音神经性耳聋模型;利用100 mmol·L^(-1) Neo和10 mmol·L^(-1) Oua可以建立长爪沙鼠HCs和SGNs均受损的感音神经性耳聋模型;利用1 mmol·L^(-1) Oua可以建立长爪沙鼠耳蜗SGNs特异性受损的耳聋模型。

关白附炮制前后对缺血性中风沙鼠药效学和代谢组学的影响

目的研究关白附生品及其炮制品对沙鼠缺血性脑中风的保护作用及对尿液代谢物的影响。方法将36只沙鼠随机分成空白组(CG)、模型组(MG)、阳性药组(PG)、生关白附组(RA)、蒸关白附组(SA)和姜矾制关白附组(GA),每组6只,除空白组沙鼠外,其余各组采用右侧单侧结扎沙鼠颈动脉造成中风模型。造模成功后,关白附给药组分别灌胃对应的饮片全粉混悬液(0.586 mg/g),阳性药组灌胃脑络通颗粒混悬液(0.390 mg/g),空白组灌胃生理盐水,共给药14 d。分别采用Longa评分法、氯化三苯基四氮唑(TTC)染色法、酶联免疫法检测关白附生品及其炮制品对神经功能学评分、脑组织梗死面积、氧化应激水平、炎症因子表达;采用超高效液相色谱-四极杆/静电场轨道阱高分辨质谱法(UHPLC-Q-Orbitrap-MS)分析空白组、模型组、阳性药组、生关白附组、蒸关白附组和姜矾制关白附组沙鼠尿液样品;采用多元统计方法对数据进行处理,筛选差异代谢物;采用京都基因与基因组百科全书(KEGG)数据库结合MetaboAnalyst 5.0软件对筛选出的差异代谢物进行代谢通路分析。结果关白附及其炮制品可显著改善脑组织梗死面积;明显降低脑组织和血清中丙二醛(MDA),白细胞介素-6(IL-6)和肿瘤坏死因子-α(TNF-α)活性(P<0.05),明显升高超氧化物歧化酶(SOD)、谷胱甘肽(GSH)、一氧化氮(NO)活性(P<0.05);代谢组学研究发现L-脯氨酸(L-Proline)、核黄素(Riboflavin)、白三烯D4(Leukotriene D4)、7-甲基黄嘌呤(7-Methylxanthine)等112种差异代谢物可作为缺血性脑中风潜在生物标志物,涉及核黄素代谢、嘧啶代谢、嘌呤代谢等14条代谢通路。生关白附回调了其中的核黄素代谢、嘧啶代谢等4条代谢通路;蒸关白附回调了其中的核黄素代谢、嘧啶代谢、精氨酸和脯氨酸代谢等5条代谢通路;姜矾制关白附回调了其中的咖啡因代谢和乙醛和二羧酸代谢2条代谢通路。结论通过比较药效学实验结果发现蒸制关白附效果较好,并明确了生品和炮制品对缺血性脑中风潜在生物标志物调节作用的异同。

Temporal and spatial distribution characteristics in the natural plague foci of Chinese Mongolian gerbils based on spatial autocorrelation

Background:The nest flea index of Meriones unguiculatus is a critical indicator for the prevention and control of plague,which can be used not only to detect the spatial and temporal distributions of Meriones unguiculatus,but also to reveal its cluster rule.This research detected the temporal and spatial distribution characteristics of the plague natural foci of Mongolian gerbils by body flea index from 2005 to 2014,in order to predict plague outbreaks.Methods:Global spatial autocorrelation was used to describe the entire spatial distribution pattern of the body flea index in the natural plague foci of typical Chinese Mongolian gerbils.Cluster and outlier analysis and hot spot analysis were also used to detect the intensity of clusters based on geographic information system methods.The quantity of M.unguiculatus nest fleas in the sentinel surveillance sites from 2005 to 2014 and host density data of the study area from 2005 to 2010 used in this study were provided by Chinese Center for Disease Control and Prevention.Results:The epidemic focus regions of the Mongolian gerbils remain the same as the hot spot regions relating to the body flea index.High clustering areas possess a similar pattern as the distribution pattern of the body flea index indicating that the transmission risk of plague is relatively high.In terms of time series,the area of the epidemic focus gradually increased from 2005 to 2007,declined rapidly in 2008 and 2009,and then decreased slowly and began trending towards stability from 2009 to 2014.For the spatial change,the epidemic focus regions began moving northward from the southwest epidemic focus of the Mongolian gerbils from 2005 to 2007,and then moved from north to south in 2007 and 2008.Conclusions:The body flea index of Chinese gerbil foci reveals significant spatial and temporal aggregation characteristics through the employing of spatial autocorrelation.The diversity of temporary and spatial distribution is mainly affected by seasonal variation,the human activity and natural factors.

Effects of levonorgestrel-quinestrol(EP-1)treatment on Mongolian gerbil wild populations:a case study

Rodent pest population outbreaks occur frequently in grassland ecosystems in northern China.The Mongolian gerbil(Meriones unguiculatus)is a dominant pest rodent which is distributed across the semi-desert grasslands of Inner Mongolia,China.In 2009,we studied the contraceptive effect of levonorgestrel-quinestrol(EP-1),concentration 50 ppm,on a wild Mongolian gerbil population.The one-off contraceptive treatment was compared with a control group using a semi-monthly live trapping method in the Ordos Semi-desert Grassland Region of Inner Mongolia.The results show that juveniles were not recruited in spring in the treatment group.Ratios of juveniles in the control and treatment groups showed significant semi-monthly differences from spring to summer(one-way ANOVA,F_(2,14)=7.53,P<0.05).Between both groups,annual fluctuations of juvenile and total population densities were significantly different respectively(F_(2,14)=4.64,P<0.05;F_(2,18)=7.72,P<0.05).The contraceptive EP-1 delayed the normal reproductive pattern of Mongolian gerbil populations.This suppressed birth rates of gerbil populations,reduced their densities,and changed their age structures.The period of EP-1 baiting should be extended but it could be an ideal method for controlling Mongolian gerbil populations during each breeding season.