Experimental skin lesions from larvae of the bot fly Dermatobia hominis

Skin biopsies from larvae of Rattus norvegicus, experimentally infested with Dermatobia hominis (Linnaeus Jr) (Diptera: Cuterebridae), were processed for histopathological studies. Two days after infestation, the first-stage larvae (L1) were located deep in the dermis, surrounded by an inflamed area infiltrated predominantly by neutrophils. On the fourth day a thin necrotic layer could be seen close to the larvae, surrounded by large numbers of neutrophils, lymphocytes, macrophages with a few eosinophils and mast cells. A small warble was formed after the fourth day, increasing in size until the seventh day, when the L1 moulted to the second-stage larva (L2). The inflammatory process continued with increasing numbers of neutrophils, macrophages, lymphocytes, eosinophils and mast cells invading the area, as well as the proliferation of fibroblasts and endothelial cells and the appearance of a few localized haemorrhages. After 18-20 days, the L2 moulted to the third-stage larva (L3), when a few plasma cells could be seen in the inflamed area. At 25-30 days there was a reduction in the necrotic layer, as well as in the number of neutrophils and lymphocytes, although large amounts of eosinophils, plasma cells, and collagen fibres were seen. The L3 usually left the host after 30 days. Two days later, the larval cavity was reduced, mast cells infiltrated the region and collagen fibre production were increased. After 7 days, an intense infiltration of plasma cells and scattered necrotic areas could be seen. A scar formed after 10 days. This study showed the laboratory rat to be a suitable model for studies of D. hominis infestation.     

Physiological changes in the Norway lobster Nephrops norvegicus (L.) escaping and discarded from commercial trawls on the West Coast of Scotland: 1. Body fluid volumes and haemolymph composition after capture and during recovery

The Norway Lobster Nephrops norvegicus (L.) was captured by trawling at depths of 120 to 150 m off the West Coast of Scotland using commercial fishing gears. Discarded animals (normally <25–35 mm carapace length) were sampled immediately after capture, and following emersion (exposure to air) on deck for 1 or 2 h. Their recovery from, and survival of, the stresses of being fished were examined in separate groups of animals transferred by SCUBA divers to underwater (u/w) cages on the seabed at a mean depth of 24 m. “Escaped” N. norvegicus were collected in a small-meshed (40 mm) “cover” around the cod-end and sampled without emersion. It was assumed that the physiological state of these animals would be similar to those passing through the cod-end meshes directly back into the surrounding sea during normal fishing operations. Groups of escaped animals were also transferred to u/w cages for recovery and survival studies. Control animals (creel-caught from the same fishing grounds) were sampled after recovery in u/w cages. Total body water content, haemolymph (blood) volume and composition were examined at various stages after capture and during recovery of control, discarded and escaped animals. Discarded animals showed significant reductions in total body water content compared to controls but recovered after 24 h. Controls that had been artificially damaged by puncturing also showed a reduction in water content. Escaped animals showed significantly higher mean water content compared to discards. Haemolymph volumes were also reduced in discarded animals suggesting that significant blood loss occurs during capture. There was also evidence of a shift of fluid from haemolymph to tissues in discarded animals. Pericardial (haemolymph) pressures were much reduced in discards compared to undisturbed control animals but showed significant recovery in surviving animals. Pressure reduction was less in escapes but was seen in control animals that had been exercised to exhaustion. Haemolymph osmotic concentrations, [Na⁺] and [K⁺] showed increases after discarding, notably after emersion, but haemocyanin [Hcy] and total haemolymph protein concentrations were less affected. The effect of these changes on longer term survival and recovery from the stress of capture are discussed.     

醋酸棉酚对褐家鼠抗生育作用的研究

1.用30毫克/公斤·日和50毫克/公斤·日棉酚饲喂褐家鼠6周,合笼交配结果表明,不仅雄性产生不育,雌性也产生不孕。 2.形态学观察,与对照组相比,棉酚主要损伤曲细精小管内精子、精子细胞和精母细胞,同时管壁萎缩、变形并明显变薄。雌性卵巢重量有所下降,形态基本正常,但子宫粘膜萎缩变薄,腺体数目显著减少。 3.由器官系数测定可知,50毫克组的雄雌褐家鼠与对照组相比,除雄性肾上腺外,其它器官都有明显的差异。     

猫尿液气味持续暴露对褐家鼠FOS表达的影响

在室内条件下以室内繁殖褐家鼠（Rattus norregicus）和Wistar大鼠为研究对象,采用免疫组织化学技术研究其分别暴露于猫尿液气味0d、1d、3d、6d、9d、18d后的FOS蛋白表达量的变化,探讨生活环境对褐家鼠反捕食对策的影响。研究结果表明,猫尿液气味暴露后室内繁殖褐家鼠下丘脑前区后部（AHP）、下丘脑腹内侧中央部分（VMHC）、杏仁核内侧核蚁背区（MeAD）、基底外侧杏仁核前部（BLA）区域内的FOS阳性细胞平均光密度与对照相比均显著增加,而在性别间无明显的差异。Wistar大鼠在猫尿液气味暴露1d、3d、6d、9d后,其下丘脑（AHP、VMHC）和杏仁核（BLA）中FOS阳性细胞的平均光密度显著高于对照组,而暴露18d后的FOS阳性细胞的平均光密度又恢复到对照水平;Wistar大鼠在AHP和MeAD区域中FOS阳性细胞的平均光密度有显著差异,而在VMHC和BLA区域中FOS阳性细胞的平均光密度无性别间差异。持续暴露猫尿液气味后两种类型褐家鼠在AHP、VMHC、MeAD、BLA区域中FOS阳性细胞的平均光密度的相对变化率也存在显著差异。以上结果表明生活环境的变化能够影响褐家鼠对捕食者气味的反应对策。     

Endogenous cardiac activity rhythms of continental slope Nephrops norvegicus (decapoda: nephropidae)

The endogenous cardiac activity rhythm of the Norway lobster Nephrops norvegicus was studied under constant conditions of darkness by means of a computer-aided monitoring system (CAPMON). Time series recordings of the heart rate (beats min^-1) were obtained from 47 adult males freshly collected from the continental slope (400-430 m) in the western Mediterranean. Periodogram analysis revealed the occurrence of circadian periodicity (of around 24 h) in most cases. A large percentage of animals showed significant ultradian periods (of around 12 and 18 h). The analysis of the circadian time series revealed the occurrence of peaks of heart rate activity during the expected night phase of the cycle. These results are discussed in relation to the emergence and locomotor activity rhythms of the species.     

澳门地区褐家鼠对溴鼠灵的抗性检测及其Vkorc1基因多态性分析

第二代抗凝血灭鼠剂因比第一代抗凝血灭鼠剂有更好的灭杀效果和安全性而被广泛使用,但长期使用同样也存在引发鼠类抗性的隐患。近年,学者已发现了第二代抗凝血灭鼠剂溴敌隆 (bromadiolone) 和鼠得克 (difenacoum) 的抗性鼠。溴鼠灵 (brodifacoum) 是一种目前在国内广泛使用且毒性极强的第二代抗凝血灭鼠剂,能引发鼠类凝血功能障碍和细胞毒性,但对于溴鼠灵是否已驱动鼠类发生抗性进化尚不清楚。澳门地区从1995年开始持续使用溴鼠灵,为研究鼠类对溴鼠灵的抗药性进化提供了良好模型。本研究于2019年10—12月在澳门地区共捕获61只褐家鼠,对其中44只开展了LFP实验 (0.005%溴鼠灵),实验鼠的平均摄毒量为 (15.28 ± 1.40) mg/kg,在7天内全部死亡。此外,对全部61只褐家鼠的维生素K环氧化物还原酶复合体亚单位1 (vitamin K-epoxide reductas complex 1, Vkorc1) 的基因序列测定表明,在Vkorc1基因外显子的已知抗药关联位点处未检测到非同义核苷酸突变,但检测到2个同义核苷酸突变 [第68位氨基酸：H (CAC)-H (CAT),突变发生率为100%;第82位氨基酸：I (ATA)-I (ATT),突变发生率为32.72%]。该研究表明,使用溴鼠灵25年后,澳门地区褐家鼠虽没有产生群体抗药性,但仍需持续监测抗药性的发生和发展。     

Spatial and temporal patterns of brown rat (Rattus norvegicus) abundance variation in poultry farms

The temporal and spatial patterns of rat abundance variations were studied, and which factors might affect these patterns in poultry farms. Forty-eight poultry farms were sampled from spring 1999 to winter 2001 in Buenos Aires, Argentina. Environmental variables of farms, meteorological variables and distances among farms were registered to evaluate a possible association with rat abundance estimated by trap success. Rattus norvegicus was the dominant rat species in the study area. Rat abundance did not vary temporally and there was reproduction at all times. Trap success was more similar among neighboured farms than among farms further apart. Contrary to the abundance of other small rodents, rat abundance was not significantly related to farm characteristics. The lack of coincidence between rats and other small rodents suggests the existence of a differential response of rats to environmental factors of the poultry farms.     

褐家鼠挖掘活动对上海九段沙湿地植物群落与土壤水盐的影响

上海九段沙是长江口的新生岛洲,目前处于草本植物群落演替阶段。为了探讨登岛褐家鼠的挖掘活动对九段沙湿地植物群落与土壤水盐的影响,我们调查了褐家鼠洞穴区的植物盖度、密度、高度、重要值、物种丰富度、物种均匀度、物种多样性、表层土壤含水量和电导率等与对照区的差异;同时,通过调查褐家鼠洞穴与潮沟在空间位置上的关系探讨了褐家鼠的栖息地选择策略。结果表明:在单一芦苇群落中,洞穴区芦苇的高度和盖度显著低于对照;在芦苇和海三棱藨草混合群落中,洞穴区芦苇的密度、相对密度、重要值和群落总盖度显著低于对照,而洞穴区海三棱藨草的密度、盖度、相对密度、相对高度和重要值显著高于对照;在碱菀和互花米草优势群落中,洞穴区碱菀的相对密度、相对盖度、重要值和群落的物种多样性指数显著高于对照,而互花米草的密度和盖度、芦苇的盖度、高度和相对盖度以及群落总盖度显著低于对照。距洞穴区中心区域洞口不同距离梯度的表层土壤含水量和电导率差异均显著。褐家鼠偏向于将洞穴营造在邻近潮沟处,这有利于提高褐家鼠在九段沙湿地的适应能力。褐家鼠的挖掘活动有利于增加碱菀和互花米草优势群落的物种多样性,会降低植物群落总盖度和表层土壤的水盐含量,对九段沙湿地植物群落的组成与演替具有重要影响。     

Dwarf male of Symbion pandora (cycliophora)

This study clarifies the identity and development of the male in the life cycle of Symbion pandora. The male is not produced directly by the feeding stage, as previously thought, but arises as a distinct individual from budding cells inside an intermediate stage named the Prometheus larva. The morphology and the development of the two distinct stages are described with light and electron microscopy. Furthermore, the following terminology is suggested to clearly distinguish between the different individuals: 1) the Prometheus larva, which is the free-swimming individual being produced inside the feeding stage; 2) the attached Prometheus larva on the feeding stage, which mostly degenerates following settlement, except for the internal budding cells; and 3) the dwarf male, which is the ciliated, sexually mature stage. The budding cells inside the attached Prometheus larva usually develop two internal dwarf males. Each dwarf male is heavily ciliated and has a well-developed nervous system with a relatively large brain, numerous gland and muscle cells, testis with bundles of sperm, and one penial structure. The male lacks a gut, as in the other free stages in the life cycle of Symbion pandora. This study also indicates that the dwarf male is freed from the attached Prometheus larva. Copulation, which has not been observed yet, probably takes place between a free-swimming male and the female, either while the female is released or afterwards.