Maintenance of pregnancy in ovariectomized Mongolian gerbils (Meriones unguiculatus)

Bilateral ovariectomy (Ovx) was carried out on day 20 of pregnancy in Mongolian gerbils ( Meriones unguiculatus ). The body weights of all groups tended to decrease on the day after the operation, and the decrease was significant in the group that was ovariectomized and given vehicle (Ovx + vehicle group). The body weight in this group never recovered until autopsy on day 24, which is normally 1 day before parturition. No fetuses survived to the time of autopsy in any of the animals of the Ovx + vehicle group. Daily administration of 4 mg of progesterone (P₄) prevented the termination of pregnancy in Ovx animals, but 1 mg did not. Treatment with estradiol 17β (E₂) in addition to 4 mg of P₄ tended to result in a lower rate of fetal survival than that of the Ovx group treated with 4 mg of P₄ alone. With regard to fetal weight, treatment with 4 mg of P₄ resulted in the same weight as in the sham-operated controls, but the addition of 0.2 or 1 μg of E₂ to the 4 mg of P₄ resulted in a significantly lower weight than that of fetuses in the 4 mg of P₄ group. The present study suggests that adequate maintenance of pregnancy in ovariectomized gerbils can be achieved by daily treatment with 4 mg of P₄ alone. Moreover, treatment with 0.2 or 1 μg of E₂ in addition to 4 mg of P₄ caused a deterioration in the maintenance of gestation, in contrast to the effects in rats, mice and hamsters.     

Undifferentiated Sarcoma of the Salivary Gland in a Mongolian Gerbil (Meriones unguiculatus)

A subcutaneous mass was found in the lower ventral neck region of a 55-week-old male Mongolian gerbil (Meriones unguiculatus). Histopathologically, the mass involved salivary glands and featured diffuse proliferation of pleomorphic neoplastic cells with large necrotic foci. The lesion was well demarcated from the surrounding tissue, although invasive growth to fibrous septa was occasionally observed. The neoplastic cells were mainly arranged in irregular sheets with severe cellular atypia, round to oval nuclei and varying amounts of eosinophilic cytoplasm. Mitotic figures and multinucleated giant cells were frequent. Immunohistochemical analysis revealed that the neoplastic cells were strongly positive for vimentin and S-100 and negative for NSE, cytokeratin, α-SMA, c-kit, factor VIII, CD34, α-1-antitrypsin, lysozyme and MSR-A. Based on the results, the mass was diagnosed as an undifferentiated sarcoma of the salivary gland. To the best of our knowledge, this is the first report of such a tumor in Mongolian gerbils.     

In vitro progesterone production of corpus luteum in pregnant Mongolian gerbils (Meriones unguiculatus)

The present study was conducted to determine the in vitro progesterone (P₄) production by Mongolian gerbil (Meriones unguiculatus) corpus luteum (CL) on days 9, 18 and 22 of pregnancy in comparison with rat CL on days 9 and 16. The culture medium of one CL per well of a 96‐well plate was changed after 4 h incubation and the CL were further cultured for 24 h. The P₄ in serum and in the medium were measured by enzyme immunoassay system. Gerbil CL weight measured after 24 h incubation was at the same level for all 3 days of pregnancy and significantly different from that of the rat CL for the 2 days of pregnancy. The serum P₄ level in gerbils was high in early pregnancy and decreased in advanced days of pregnancy. In contrast, the P₄ in rats was higher in the latter half of pregnancy. In vitro P₄ production by a single CL after 4 h incubation decreased significantly during the days of pregnancy in both the gerbil and the rat. P₄ values produced by the gerbil CL for 24 h incubation were significantly higher than after 4 h incubation in all 3 days of pregnancy, however, there was no difference between the two incubation time groups in the rat. In vitro P₄ production by CL correlated well with the serum P₄ level on the 3 days of pregnancy in the gerbil. In the rat, however, the relationship was inversed between the two parameters. The correlation in this experiment suggested that CL is the sole source of P₄ for the maintenance of the gerbil pregnancy, with the result of abortion after an ovariectomy on day 20 of pregnancy as described in our previous report.     

Impairment of cellular and humoral immunity in overweight Mongolian gerbils (Meriones unguiculatus)

Animal immunity is usually impaired in obesity. We know little about the effect of being overweight or obese on the immune function of wild rodents. The present study is aimed to test the hypothesis that immunity is suppressed in overweight Mongolian gerbils (Meriones unguiculatus). In the study, 16 overweight (body mass: 90.8–127.6 g) and 16 lean gerbils (body mass: 60.5–77.7 g) were randomly selected from a total of 174 male gerbils (body mass range: 55.8–144.7 g). Half of the overweight and lean males were injected with sterile saline; the others were immunochallenged (IC) with phytohaemagglutinin and keyhole limpet hemocyanin to assess cellular and humoral immunity, respectively. Body fat mass, wet and dry spleen mass, leukocyte counts, blood glucose levels and serum leptin levels were significantly higher in the overweight gerbils than in the lean gerbils. However, phytohemagglutinin response indicative of cellular immunity and immunoglobulin G concentrations was significantly lower in the IC overweight gerbils than in the IC lean gerbils. These results indicate that cellular and humoral immunity are impaired in the overweight gerbils. Excessive body fat mass, higher leukocyte counts and serum leptin levels imply that overweight gerbils are in a low grade inflammatory state.     

瑞香狼毒根对长爪沙鼠的急性毒力测试

本文采用含17%瑞香狼毒(Stellera chamaejasme)根粉末的毒饵,依据孙氏改良寇氏综合计算法,实验室内测定了其对长爪沙鼠(Meriones unguiculatus)的急性毒力。根据预试验结果,采用最低剂量为7.0 g·kg^-1,最适剂量梯度比值K=0.65的5个剂量梯度的瑞香狼毒根毒饵饲喂长爪沙鼠。结果显示:试验组试鼠体重明显下降(P=0.029<0.05),完全致死组肝脏重/体重比对照组明显减小(P=0.014<0.05),但肾脏略增大(P=0.102>0.05)。其对长爪沙鼠的LD50为(20.37±0.086)g·kg^-1,95%平均可信限为(20.37±7.84)g·kg^-1,属弱毒水平。     

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.     

Comparative sequence analysis of four myosin heavy chain isoforms expressed in porcine skeletal muscles: Sequencing and characterization of the porcine myosin heavy chain slow isoform

A nucleotide sequence including the full coding region for the myosin heavy chain (MyHC) slow isoform was determined from the longissimus skeletal muscle. The deduced amino acid sequence was 1935 residues, which was the same length as the human and rat MyHC-slow isoforms. The porcine MyHC-slow isoform showed 97.6% and 97.4% amino acid identities to the human and rat isoforms on their entire regions, respectively. The functional regions were also highly conserved among mammalian MyHC-slow isoforms. Amino acid substitutions between the porcine MyHC-slow and MyHC-fast isoforms were concentrated on the functional regions. Loop 1, the controlling region of nucleotide binding and release, was conserved among the fast isoforms, but not between the slow and fast isoforms. Loop 2, a part of the actin binding region, was not conserved among any of the isoform types, and the most substitutions in this region were found in the slow isoform. The myosin essential light chain binding region was conserved among the fast isoforms, except for some substitutions in the 2b isoform, but was clearly different in the slow isoform. The myosin regulatory light chain binding region was conserved among the fast isoforms, but not between the slow and fast isoforms. These results indicate that the functional difference between the porcine MyHC-slow and -fast isoforms are controlled by the sequence diversity at the four functional regions compared.     

黄嘴白鹭集群繁殖对营巢地土壤重金属积累的效应

本研究采用电感耦合等离子质谱(ICP-MS)方法,测定福建漳浦菜屿岛黄嘴白鹭(Egretta eulophotes)排泄物的重金属元素(V、Cr、Mn、Ni、Cu、Zn、Cd、Se、Pb)及半金属元素(As)的含量,分析比较黄嘴白鹭繁殖之前和繁殖之后的集群营巢地、非营巢地的表层土壤的重金属元素及半金属元素含量的变化.结果显示:在本次测定的所有排泄物和土壤样本中均未检出元素Se和Cd:非营巢地土壤中各元素的含量在繁殖前后都没有显著差异(p>0.05),营巢地土壤中的Zn和Pb元素的含量在繁殖前后有极显著差异(p<0.01).营巢地和非营巢地土壤之间的元素含量比较结果发现,繁殖之前两地土壤之间的Zn含量存在极显著差异(p<0.01);繁殖之后两地土壤之间的Cu、Zn、As、Pb存在极显著差异(p<0.01),V、Ni存在显著差异(p<0.05).上述数据说明黄嘴白鹭的集群繁殖活动对湿地和海岛生态系统之间的重金属转移起着重要作用,长时间则可能造成海岛营巢地土壤的重金属污染.     

PCR制备地高辛标记的探针检测禽流感病毒核酸

用聚合酶链反应（PCR）技术,制备了广东禽流感无致病力分离株A/goose/China/24/96(H7N3）核蛋白基因片段（NPc）的地高辛标记的cDNA探针。建立并优化了检测禽流感病毒核酸的探针杂交法,探针杂交法能鉴别出非免疫鸡胚和SPF鸡胚尿囊液中的病毒,攻毒后第3天的SPF和非免疫鸡泄殖腔拭子中AIV的最大检出率为1/10,对临床样品中的AIV的最大检出率为1/7,而直接HA和HI法及AGP试验检不出临床样品的AIV。该探针具有较好的特异性和敏感性,为从分子水平探讨AIV的发病机理、临床早期快速诊断提供了新的研究手段。