The case of an insular molarless black rat: Effects on lifestyle and mandible morphology

We report a specimen of an insular black rat (Rattus rattus) from Illa den Colom (Menorca, Western Mediterranean) displaying a singular dental characteristic. It has no molar teeth but displays regular incisors. Its mere occurrence as a regular adult rat is puzzling and we attempted to evaluate what diet and morphological changes in jaw shape were promoted by the total lack of molars, and allowed the successful survival of this specimen. Two approaches were performed: first, bone tissue was analysed to obtain δ¹⁵N and δ¹³C values in order to estimate dietary preferences of the rat. Second, the shape of the jaw was analysed through elliptic Fourier analysis, using outlines as markers of diet. The values for C and N fractionation (−19.89‰ and 10.06‰, respectively) suggest that the molarless rat included animal food in the diet and not exclusively plant material as observed in other mainland rat populations. The morphometric analysis in which the shape of the molarless mandible falls into the range of omnivorous groups leads to a similar conclusion. The adult age of the specimen suggests that it fed efficiently enough with its incisors to allow a normal growth. Although displaying a lack of molar teeth, no deep changes in remodelling jaw morphology can be observed and its shape falls into the variation of regular murines. The molarless rat exemplifies that special ecological features on small islands allow the survival of aberrant morphotypes.     

Helminth communities and host-parasite relationships in argentine brown rat (Rattus norvegicus)

Summary  The aims of this research were: 1) to determine the helminth parasite fauna of seventy two Rattus norvegicus (Berkenhout, 1769) individuals inhabiting poultry farms in the Pampean region of Argentina; 2) to examine the relationship between parasitism and individual characteristics of the hosts, and 3) to analyze the associations among helminths. The study was carried out in twenty-four poultry farms from autumn 2000 to winter 2001. Nematodes were found in the intestine or caecum rectum of the 74 % of rats and cestodes were found along all the intestine of the 28 % of rats. Heterakis spumosa (Travassos 1914) was a central species, whereas Syphacia muris, Yamaguti 1941, Nippostrongylus brasiliensis (Travassos 1914) and Hymenolepis diminuta (Rudolphi 1819) were satellite species. Helminths do not affect rat survival and growth of rats. Rats parasitized with H. spumosa and H. diminuta were larger and older than non-parasitized rats. The intensity of infection with H. spumosa significantly increased with rat age. Rats parasitized with Nippostrongylus brasiliensis and Syphacia muris did not differ in size and age with respect to non-parasitized ones. The mean intensity of infections per host was 33.74, 74.28, higher than 200, and 3.10 for H. spumosa, S. muris, N. brasiliensis and H. diminuta, respectively. The mean intensity of infection with H. spumosa was higher in summer than in the other seasons, while the higher mean intensity of infection with N. brasiliensis and S. muris occurred in autumn. Infections with Heterakis spumosa and Syphacia muris, and with Syphacia muris and Nippostrongylus brasiliensis were independent; while Heterakis spumosa and Nippostrongylus brasiliensis were negatively associated.     

Diurnal variations of calcium transport in the small intestine of adrenalectomized,nephrectomized, and vitamin D-treated rats

Summary Everted gut-sac-technique was used to study diurnal periodicity of active calcium transport in the small intestine of the adult rat maintained under 12:12 hours light-dark cycle. Similar to intact rats, diurnal fluctuations of the transport capacity persisted in adrenalectomized animals and in rats treated with 100,000 units of vitamin D₃. Bilateral nephrectomy resulted in significant dampening of diurnal transport fluctuations. In contrast to the differences in calcium transport, diurnal changes of the calcium binding protein did not appear to be statistically significant when investigated in the intact, vitamin D-treated and nephrectomized rats.     

6种常用灭鼠剂对黄胸鼠药效测试

目的测试6种武汉常见市售灭鼠剂对黄胸鼠药效。方法在实验室做无选择摄食实验,测试6种灭鼠剂对黄胸鼠的药效。结果3号灭鼠剂毒杀率最高为80%,其次为5号和6号毒杀率为70%;4号灭鼠剂毒杀率为60%,1号和2号灭鼠剂毒杀率最低,为10%(表2)。1号和2号与4号鼠药对黄胸鼠的杀灭率有显著差异(P0.05),与3号、5号和6号鼠药有极显著差异(P0.01)。结论在以黄胸鼠为主的地点灭鼠可以选用3、4、5、6号灭鼠剂或增加灭鼠剂在现场存留时间。     

大鼠胚胎中脑多巴胺神经元的分离培养与鉴定*

背景：神经细胞移植治疗是最有希望治愈帕金森病的方法之一。 目的：探讨大鼠胚胎中脑多巴胺神经元分离、培养与鉴定的方法。 方法：解剖分离E14d SD大鼠胚胎中脑组织,制备单细胞悬液,以神经细胞培养液培养,观察其生长情况并进行RT-PCR和免疫组织化学鉴定。 结果与结论：在神经细胞培养液中,细胞生长良好。RT-PCR和免疫组织化学结果显示大多数细胞表达多巴胺神经元特异性分子标志。证实实验成功建立了大鼠胚胎中脑多巴胺神经元分离培养与鉴定的方法。     

湛江市褐家鼠对杀鼠灵的抗药性调查

目的 检测采自广东省湛江市区的褐家鼠对第一代抗凝血灭鼠剂的抗性发生水平.方法 将捕自湛江市的褐家鼠在室内预试验一段时间后,对合格试鼠采用无选择性摄食试验法以0.005％杀鼠灵毒饵饲毒(LFP法),观察并分析试鼠的死亡率与食毒量的关系.结果 本次褐家鼠抗性检测合格试鼠计37只,检测结束后试鼠因药物死亡29只,试鼠对杀鼠灵的抗性发生率为21.62％,已经形成抗性种群;死亡试鼠性别间在致死剂量和死亡时间上差异均无统计学意义(P＞0.05);全部死亡试鼠平均食毒剂量为( 19.14± 5.44)mg/kg,平均死亡时间(7.34±3.51)d.结论 湛江市区的褐家鼠防治应选用第一代抗凝血灭鼠剂以外的药物,同时注意监测害鼠对药物的敏感度变化,以节省有限的药物资源.     

成都市城区鼠种群密度与褐家鼠汉坦病毒带毒率调查

[目的]通过对成都市褐家鼠汉坦病毒带毒率调查,发现成都市肾综合征出血热(HFRS)鼠传播特征,为科学指导HFRS防制提供依据。[方法]鼠密度调查采用粉迹法,用免疫荧光法测定汉坦病毒抗原。[结果]成都市鼠密度灭前为8.18%,灭后为2.40%;褐家鼠带病毒率为4.42%。[结论]成都市市区褐家鼠种群携带汉坦病毒,在防制成都市肾综合征出血热时应以控制褐家鼠种群密度为主。     

褐家鼠对杀鼠灵和溴敌隆抗药性的测定

目的试验观察虹口区城区褐家鼠对第一代抗凝血剂杀鼠灵和第二代抗凝血剂溴敌隆的抗药性发生率,为家栖鼠防治提供依据。方法采用0.005%杀鼠灵毒饵和0.005%溴敌隆毒饵进行无选择性摄食试验。结果 0.005%杀鼠灵毒饵,25只褐家鼠未监测到抗药性个体;0.005%溴敌隆毒饵,27只褐家鼠抗药性发生率为3.7%(1/27)。结论在虹口区城区,褐家鼠对第一代抗凝血剂杀鼠灵敏感,但存在对第二代抗凝血剂溴敌隆的抗药性,应加强对灭鼠药物的敏感性监测,科学、合理用药。     

莆田地区褐家鼠种群动态和繁殖生态研究

1987年3月至1989年2月,逐月在莆田地区研究了褐家鼠种群动态和种群繁殖生态,共布放14400笼日,捕获褐家鼠946只(382♂,564♀),捕获率为6.57%,占家鼠总数33.30%。种群数量及其在家鼠中的组成比,有一定的季节变化和年度差异。通过逐只观察雌、雄生殖器官的特征和变化,对种群的性比,雌鼠睾丸下降率、繁殖雌鼠率、怀孕率、胎仔数、繁殖指数的季节变化和年度差异进行了深入的研究和比较,分析了种群数量动态和种群繁殖之间的关系,发现种群密度对种群繁殖有明显的反馈调节作用。