Comparison of ultrasonic vocalizations emitted by rodent pups.

Ultrasonic vocalizations (USVs) emitted by rodent pups, mouse, rat, Syrian hamster, vole, and Mongolian gerbil, were compared as a basic study for a screening test of anti-panic drugs. USVs of rodent pups, separated from their mother under a low temperature condition, were collected by Real-Time Spectrogram (RTS) apparatus, and transformed into spectrograms and power spectra by SIGNAL software. Waveforms of USVs emitted by the rodent pups showed several characteristic features, and species specificity of USVs was shown. We think that the species specificity might be due to differences of the anatomical structures in the respiratory tract and respiratory patterns in rodent pups.     

High resistance of cultured Mongolian gerbil cells to X-ray-induced killing and chromosome aberrations.

The Mongolian gerbil (Meriones unguiculatus) is known to be one of the most radioresistant animals. We have examined the X-ray sensitivity of normal diploid fibroblasts from Mongolian gerbil embryos compared with those of cultured embryo cells obtained from various laboratory animals and a normal human. There was a wide difference in X-ray sensitivity for cell killing among different mammalian species. The D0 values for Mongolian gerbil cells ranged from 2.08 to 2.28 Gy, values which are twice as high as those for human cells. The mean D0 value for human cells was 1.06 Gy. Mouse, rat, Chinese hamster, and Syrian/golden hamster cells showed similar D0 values ranging from 1.30 to 1.56 Gy. When cells were irradiated with X rays, ten times more chromosome aberrations were detected in human cells than in Mongolian gerbil cells. The frequencies of chromosome aberrations in other rodent cells were between the values for cells from humans and those from gerbils. These data indicate that the Mongolian gerbil cells are resistant to X-ray-induced cell killing and chromosome aberrations, and that the radiation sensitivity of mammalian cells in primary culture may be reflected by their radioresistance in vivo.     

Olfactory and Thermal Influences on Ultrasonic Vocalization During Development in Rodents

Ultrasounds are emitted by developing rodents, and changes withage in several parameters of vocalization have been reportedfor numerous myomorphs. In this paper I integrate with ultrasonicvocalization several behaviors which change during development.Included are studies controlling stimulation by olfactory, thermal,and tactile cues as well as detailed studies of specific responsessuch as movement, suckling, grooming, and huddling. Developmentis analyzed in well-known species, such as the rat (Rattus norvegicus),and in less familiar species, especially the pine vole (Microtuspinetorum). Lacking the capacity for physiological thermoregulation, altricialrodent pups with their mother use several behavioral strategieswhich facilitate thermoregulation. Inside the nest, pups adjustthe temperature by changing their huddling. The mother regulatesthe length of suckling bouts according to her body temperature.When a pup is removed from the warm nest, vocalizations of thepup can increase the likelihood of retrieval by the mother andthereby indirectly facilitate thermoregulation. In several species which have been studied, vocalization ratesare highest when pups begin to move into and out of nests andexhibit olfactory-directed movement. As olfactory preferencesbecome established and movement is coordinated, a decline invocalization appears in rat, mouse, hamster, spiny mouse, andpine vole. In the gerbil, however, the decline precedes competencein olfactory-directed movement. In the presence of home shavings, young rats emit low ratesof vocalization, while pine vole young emit calls at a highrate. This contrast may relate to the intensive attachment ofyoung pine voles to the mother in early life.     

Decrease of Plasma Platelet-Activating Factor Acetylhydrolase Activity in Lipopolysaccharide Induced Mongolian Gerbil Sepsis Model

Platelet-activating factor (PAF) plays an important role in the pathogenesis of sepsis, and the level of plasma PAF acetylhydrolase (pPAF-AH), which inactivates PAF, decreases in sepsis patients except for the sepsis caused by severe leptospirosis. Usually, increase of pPAF-AH activity was observed in lipopolysaccharide (LPS)-induced Syrian hamster and rat sepsis models, while contradictory effects were reported for mouse model in different studies. Here, we demonstrated the in vivo effects of LPS upon the change of pPAF-AH activity in C57BL/6 mice and Mongolian gerbils. After LPS-treatment, the clinical manifestations of Mongolian gerbil model were apparently similar to that of C57BL/6 mouse sepsis model. The pPAF-AH activity increased in C57BL/6 mice after LPS induction, but decreased in Mongolian gerbils, which was similar to that of the human sepsis. It thus suggests that among the LPS-induced rodent sepsis models, only Mongolian gerbil could be used for the study of pPAF-AH related to the pathogenesis of human sepsis. Proper application of this model might enable people to clarify the underline mechanism accounted for the contradictory results between the phase II and phase III clinical trials for the administration of recombinant human pPAF-AH in the sepsis therapy.     

Comparative study on isolation calls emitted from hamster pups.

Waveforms of isolation calls emitted from hamster pups, which were Syrian hamsters, Djungarian hamsters, and Chinese hamsters, were compared in a basic study on improving reproduction by decrease of cannibalism, because it was reported that maternal behavior was induced by isolation calls in rodents. Isolation calls of hamster pups, isolated from their mother and receiving cold stress, were collected by Real-Time Spectrogram (RTS), and calculated to spectrograms and power spectra by SIGNAL. Isolation calls consisted of ultrasonic vocalizations (USVs) and audible vocalizations (ADVs) in each species. Waveforms of isolation calls emitted by the hamster pups, were shown to have several characteristic features. In this study, the species specificity of isolation calls was shown in hamster pups. It would seem that the species specificity originates in the differences of sensitivity to cold stress via the autonomic nerve in hamsters.     

HVJ infection in alveolar macrophages of various laboratory animals

Alveolar macrophages (AM) in bronchoalveolar lavage derived 6 species of laboratory animals (mouse, rat, Syrian hamster, Mongolian gerbil, guinea pig, and rabbit) were cultivated in vitro and were infected with HVJ, parainfluenza virus type 1, for the purpose of studying virus reproduction in these cells. Using infectivity assay, fluorescent antibodies and hemadsorption techniques, three categories were proposed depending on the potential of virus replication and antigen production. Category 1 (mouse, Syrian hamster, and guinea pig AM) was the most susceptible group to HVJ infection. All AM became antigen positive, and more than 10(6) PFU/ml of virus infectivity in the culture fluids was noted at 4 days after the virus infection. Rat and Mongolian gerbil AM were grouped into Category 2. Their AM showed a moderate virus yield (average 10(5) PFU/ml of infectivity) and antigen production. On the other hand, Category 3 (rabbit AM), exhibited no production of an infectious virus. It was likely that the virus penetrated into the AM but did not replicate complete virus. However, antigen positive cells ranging from 10 to 50% depended on the multiplicity of the infection to the AM. These findings suggest that HVJ infection in the rabbit AM was abortive (incomplete virus replication), since trypsin treatment of the culture fluids, which may contain incomplete HVJ particles, did not induce infectivity.     

鼠类超声波通讯的社会原因和功能

鼠类的超声通讯已有报道,并且在实验室深入研究了小鼠和大鼠接受和释放这些叫声的能力。由于对不同刺激的反应和出自不同的目的,幼鼠和成年鼠都释放超声。发出者的年龄/性/品系以及自然和社会环境的不同,导致这些超声的频率和持续时间也不同。在社会隔离和操作处理时,未成年个体可释放超声波。作为成熟程度以及对环境信号和药物处理时反应的指标,这些叫声得到了广泛研究,表明超声在调节出生后早期的母幼联系中起相应的作用。随着幼鼠的长大及体温调节和感觉能力的增强,发生的数量大大减少。然而,成年小鼠和大鼠在不同的社会条件下,释放出的超声有种间差异:大鼠的超声与正面和负面的社会作用有关,而在小鼠中,这些叫声主要与领域有关.     

长爪沙鼠线粒体DNA控制区全序列测定及分析

目的对长爪沙鼠线粒体DNA控制区全序列进行测定,并对其进行鉴定及进化分析。方法根据长爪沙鼠已知基因序列设计引物,采用PCR产物测序法,对所得的片段进行测序鉴定。结合已公布啮齿类动物D-loop区序列,分析其碱基组成、遗传距离、并基于最小进化法和UPGMA法构建系统进化树。结果获得长爪沙鼠D-loop区序列,其与家鼠、小家鼠和仓鼠平均同源性为58%;碱基组成分析显示,长爪沙鼠与啮齿类动物有相似的碱基组成和碱基偏离,其A-skew和G-skew分别为0.0047和-0.28。进化分析结果显示,长爪沙鼠与家鼠（0.35）、黑家鼠（0.38）和仓鼠（0.39）具有较近的遗传距离,其分化顺序为跳鼠、蔗鼠、长爪沙鼠、仓鼠、家鼠和小家鼠。结论本研究获得长爪沙鼠D-loop区全序列,确定了长爪沙鼠与仓鼠、家鼠、小家鼠及其它啮齿动物的进化关系,为长爪沙鼠进化研究、线粒体的结构和功能研究奠定基础。     

内蒙古草原五种啮齿动物肾脏形态学特征比较

啮齿动物的水平衡能力对其适应干旱环境至关重要。为理解啮齿动物对水环境的适应性,本研究以分布于内蒙古草原的长爪沙鼠 (Meriones unguiculatus)、布氏田鼠 (Lasiopodomys brandtii)、小毛足鼠 (Phodopus roborovskii)、坎氏毛足鼠 (Phodopus campbelli) 和黑线仓鼠 (Cricetulus barabensis) 为研究对象,测定了肾脏形态学指标、肾单位密度指标和尿液渗透压等,比较分析了肾脏形态结构与栖息地环境之间的关系。结果发现：5种啮齿动物肾脏髓质厚度随动物分布区域的变化,呈现从典型草原地区、半荒漠地区至荒漠和沙漠地区逐渐增加的趋势,干旱地区动物的尿液渗透压较高。5种动物的皮质肾单位密度无显著差异。近髓肾单位密度统计显示,黑线仓鼠大于小毛足鼠与坎氏毛足鼠,布氏田鼠与长爪沙鼠居中。这些结果表明,啮齿动物的肾脏形态指数和组织学指数可以在一定程度上反映哺乳动物肾脏浓缩尿液的能力,肾脏的结构具有可塑性以应对环境的变化。     

Rederivation of Helicobacter hepaticus-infected Mongolian gerbils by Caesarean section and cross-fostering to rats and mice

The Mongolian gerbil serves as an animal model for a wide range of diseases. As these animals are extensively used for the study of Helicobacter pylori-induced gastritis, naturally occurring infections with rodent Helicobacter species in gerbils are a possible source of interference in studies of H. pylori-associated disease. The gerbil stock at the Central Animal Facility in Hannover was persistently infected with H. hepaticus. The aim of this study was to derive Helicobacter species-free Mongolian gerbils. Therefore, germfree gerbil pups were obtained by Caesarean section and the pups were transferred to female rats and mice with recently delivered litters. In total, four Ztm:NMRI mice, four Ztm:SPRD rats and one DA/Ztm rat that originated from a specified pathogen-free area were selected to serve as foster mothers. With this approach, it was possible to obtain Helicobacter-free gerbils. Rearing by mice was more successful than by rats, as six of nine gerbils were reared by mice, but only one of 29 gerbils was reared by rats.     

The effects of repeated early deprivation on ultrasonic vocalizations and ontogenetic development in mandarin vole pups

Early deprivation is popularly used in rodent models as an early life social stress to investigate and determine the factors that affect the development of the brain and behavior. Ultrasonic calls made by pups play an important role in parental–pup interactions during the neonatal period. However, whether repeated early deprivation affects the properties of ultrasonic vocalizations (USVs) produced by mandarin vole (Microtus mandarinus) pups, and whether ontogenetic development is subsequently affected, remains unclear. Here we measured USVs and developmental parameters in mandarin vole pups deprived of their parents and littermates for 3 h per day (ED, which is significantly different from 5 min isolation used to induce USVs) and another pup group developed under normal nest conditions (PC). Repeated measures analysis indicated that the number of USVs from ED pups was significantly lower than those from PC pups during the postnatal period (p < 0.05). The pulse durations of ED pups were longer than those of PC pups at two (p < 0.001) and five days of age (p < 0.05), but shorter at 14 days of age (p < 0.001). Compared with PC pups, the frequency range of the ED pups was wider at 18–45 kHZ, variable during the first week, smaller and narrower at 18–30 kHZ at eight and 11 days of age, and became stable similar to PC pups at 25 kHZ after 14 days of age. ED also reduced pup body weight significantly and resulted in earlier eye opening compared with PC pups (p < 0.001). A positive relationship was also found between USV emissions and levels of parental care received by pups. It appears that pup USVs are an important age-dependent behavioral phenotype and an effective communicative method between parents and offspring. Prolonged parental and littermate deprivation (ED) may alter USVs emitted by pups and then ontogenetic development and parental care. Mandarin voles show USV properties similar to socially monogamous rodents and this add further support to the hypothesis that species with different social systems produce different patterns of ultrasonic vocalizations. USVs, ontogenetic development and parental care are closely associated.     

Chromosome assignment of four plexin A genes (Plxna1, Plxna2, Plxna3, Plxna4) in mouse, rat, Syrian hamster and Chinese hamster

We determined chromosome locations of four plexin A subfamily genes, Plxna1, Plxna2, Plxna3 and Plxna4, in four rodent species, mouse, rat, Syrian hamster and Chinese hamster, by fluorescence in situ hybridization. Plxna1, Plxna2, Plxna3 and Plxna4 were localized to Chr 6E2, 1H6, XB-C1 and 6B1 in mouse, Chr 4q34.1, 13q26-->q27, Xq37.1-->q37.2 and 4q21.3-->q22 in rat, Chr 8qb1.1-->qb1.3, 11qb8, Xpb8 and 5qb3.3 in Syrian hamster, and Chr 8q1.2, 5q3.7, Xp2.7 and 1q2.2-->q2.3 in Chinese hamster, respectively. All the mouse and rat plexin A genes were localized to chromosome regions where conserved homology has been identified among human, mouse and rat.     

Species differences in hepatic peroxisome proliferation, cell replication and transforming growth factor-beta1 gene expression in the rat, Syrian hamster and guinea pig

The objective of this study was to evaluate species differences in the hepatic effects of three potent rodent peroxisome proliferators, namely methylclofenapate (MCP), ciprofibrate (CIP) and Wy-14,643 (WY), particularly with respect to effects on replicative DNA synthesis and transforming growth factor-beta1 (TGF-beta1) gene expression. Male Sprague-Dawley rats, Syrian hamsters and Dunkin-Hartley guinea pigs were given daily oral doses of 0 (corn oil) and 75 mg/kg MCP for periods of 6 and 21 days. Syrian hamsters and guinea pigs were also treated with 25 mg/kg CIP and 25 mg/kg WY. Relative liver weights were significantly increased in peroxisome proliferator-treated rats and Syrian hamsters, but not in guinea pigs. Hepatic peroxisomal (palmitoyl-CoA oxidation) and microsomal (lauric acid 12-hydroxylase) fatty acid oxidising enzyme activities and CYP4A isoform mRNA levels were significantly increased in rats and Syrian hamsters, whereas only minor effects were observed in the guinea pig. Replicative DNA synthesis was studied by implanting 7-day osmotic pumps containing 5-bromo-2'-deoxyuridine during study days -1 to 6 and 14 to 21. Hepatocyte labelling index values were increased by MCP in the rat, but neither MCP, CIP nor WY produced any significant effect on replicative DNA synthesis in the Syrian hamster and guinea pig. MCP treatment increased TGF-beta1 and insulin-like growth factor II/mannose-6-phosphate (IGFII/Man6P) receptor gene expression in the rat. In the Syrian hamster, effects on TGF-beta1 and IGFII/Man6P receptor gene expression were also observed in some instances, whereas TGF-beta1 mRNA levels were essentially unchanged in the guinea pig. These results provide further evidence for marked species differences in response to rodent peroxisome proliferators. While peroxisome proliferators produce a wide spectrum of effects in rat liver, other species such as the Syrian hamster and guinea pig are less responsive and in the case of some endpoints (e.g., cell replication) may be refractory.     

人为疼痛刺激下金色中仓鼠幼鼠叫声的发育过程

金色中仓鼠幼鼠可以利用可听声和超声信号与母鼠进行交流,这些声音可以反映个体的寒冷、饥饿、疼痛等不同生理状态和需求。因疼痛诱发的叫声对于维持幼鼠的存活也有着重要意义。本实验通过录制人为疼痛刺激下,不同日龄金色中仓鼠的叫声,分析并比较了5 - 30 日龄金色中仓鼠不同发声信号特征(可听声出现频次、可听声持续时程、可听声主频率、超声出现频次、超声持续时程、超声主频率)的性别差异;同时记录了幼鼠的两种发声随日龄的变化趋势。结果发现:幼鼠两种叫声的各种参数均未表现性二型现象。幼鼠超声发生频次随日龄增加而逐渐减少。而可听声却正相反,随日龄增加而逐渐上升,并在20 日龄时达到最高峰,之后逐渐下降。可听声持续时程也随日龄而增加。综上,在人为疼痛刺激下,随着日龄增加,幼鼠更倾向于使用可听 声而非超声与母兽进行交流。     

Comparative aspects of microsomal cytochrome P-450-dependent monooxygenase activities in musk shrew (Suncus murinus), Mongolian gerbil (Meriones unguiculatus), harvest mouse (Micromys minutus) and rat.

1. The cytochrome P-450 content (0.75 +/- 0.13 nmol/mg microsomal protein) in musk shrew (suncus, Suncus murinus) liver microsomes was lower than that (1.30 +/- 0.26) in rat liver microsomes, but it is approximately the same level as in the Mongolian gerbil (Meriones unguiculatus, 1.18 +/- 0.14), harvest mouse (Micromys minutus, 1.11 +/- 0.02) and rat. 2. The hydroxylation activity (based on cytochrome P-450) of medium-chain fatty acids (otanoic, decanoic, lauric and tridecanoic acids) is much higher in suncus, Mongolian gerbil and harvest mouse than in rat, with the exception of the activity of decanoic and tridecanoic acids in Mongolian gerbil. 3. This suggests that cytochrome P-450 species catalyzing the hydroxylation of medium-chain fatty acids are present in these laboratory animals in higher concentrations. 4. The aminopyrine N-demethylation activity based on microsomal protein or cytochrome P-450 in suncus is significantly lower than that in rat, but the N-demethylation activity in Mongolian gerbil and harvest mouse is approximately 1.7-2.0-fold greater than that in rat.     

Comparison of basal glutathione S-transferase activities and of the influence of phenobarbital, butylated hydroxy-anisole or 5,5'-diphenylhydantoin on enzyme activity in male rodents

1. Hepatic cytosolic glutathione S-transferase (GST) activities, toward five substrates, were shown to vary markedly among three laboratory rodent species. 2. Basal GST activities for 1-chloro-2,4-dinitrobenzene (hamster greater than mouse greater than rat), 1,2-dichloro-4-nitrobenzene (mouse greater than rat greater than hamster), p-nitrobenzyl chloride (rat = mouse = hamster), bromosulfophthalein (rat greater than mouse greater than hamster) and 1,2-epoxy-3-(p-nitrophenoxy)propane (mouse greater than rat = hamster) differed with respect to magnitude and distribution among species. 3. GST substrate activities in response to phenobarbital, butylated hydroxy-anisole or 5,5'-diphenylhydantoin treatment were increased more often in mouse and rat as compared to the hamster. 4. These results suggest that basal GST activity, as well as inducibility, differ among rodent species. Since GST are involved in detoxication processes, differences in GST properties may underlie variability in species sensitivity to toxicants.     

Comparison of glycoprotein hormone alpha-subunits of laboratory animals

The common alpha-subunit of glycoprotein hormones (CGalpha) is a core protein shared by follicle-stimulating hormone (FSH), luteinizing hormone (LH), and thyroid-stimulating hormone (TSH). In order to obtain a molecular basis for an efficient superovulation technique applicable to a wide range of animal species and to discuss the phylogenetic aspect based on molecules related to the reproductive system, we determined cDNA sequences of CGalpha in seven laboratory animals: the guinea pig, Mongolian gerbil, golden hamster, mastomys, Japanese field vole, the JF1 strain of Mus musculus molossinus, and rabbit. Comparison of the inferred CGalpha amino acid sequences of these animals and other mammals (human, mouse, rat, cow, pig, and sheep) showed that the signal peptides and the first ten residues at the N-terminus of the apoprotein were variable, while the rest of the apoproteins were highly conserved. In particular, all rodents had a leucine residue at the apoprotein N-terminus, except the guinea pig, which had a phenylalanine residue, as in the cow, pig, sheep, and rabbit. Phylogenetic trees constructed from amino acid sequences suggest a closer relationship between the guinea pig and artiodactyls than to rodents, confirming the taxonomic peculiarity of the guinea pig.     

Innervation of the incisors and periodontal ligament in several rodents: an immunohistochemical study of neurofilament protein and glia-specific S-100 protein

The present immunohistochemical study by use of antisera against neurofilament protein (NFP) and S-100 protein dealt with the innervation of the upper incisors and periodontal ligament in five species of rodents including the guinea pig, hamster, Mongolian gerbil (Meriones unguicularis), mouse and squirrel (Tamias sibiricus). The innervation pattern of the periodontal ligament and dental pulp in the incisors of five rodents was fundamentally identical to that in the rat, which we have previously demonstrated by the same method. The NFP-positive Ruffini-like corpuscles were concentrated in the middle region of the lingual periodontal ligament in all the species examined, suggesting that this particular arrangement of Ruffini-like corpuscles, possibly stretch receptors, was essential to the rodent incisor. The labial periodontal ligament, on the other hand, contained less numerous NFP-positive nerves, these terminating among collagen fibers as free endings. The gerbil and squirrel in particular possessed only a few nerve fibers in the labial periodontal ligament. It was thus presumed that the labial periodontal ligament might be less significant as a mechanoreceptive site than the lingual periodontal ligament. The NFP-positive pulpal nerves, beaded or smooth in shape, ran parallel to the tooth axis, but never extended to the odontoblastic layer; no subodontoblastic plexus was found in the incisors of any of the rodents. S-100-immunopositive nervous elements were distributed in the periodontal ligament and dental pulp of all the rodent species examined, showing a distribution pattern similar to the NFP-positive nerves. Only in the squirrel did odontoblasts show an intense S-100 immunoreactivity.     

Discomfort-related changes in pup ultrasonic calls of fat-tailed gerbils Pachyuromys duprasi

Rodent pups vocalize when placed in social isolation. We apply a method of “joint calls” for examining discomfort in rodent pup ultrasonic (>20 kHz) calls. Previously, this method has been developed for audible calls of fur farm mammals. Using a repeated measures design to exclude effects of individual identity and age on the analysed variables, we compared the ultrasonic call variables produced by 8–40-day pups of fat-tailed gerbils Pachyuromys duprasi during two subsequent experimental stages, the Isolation Stage and the Handling Stage. We considered that discomfort-related negative emotional arousal increased towards the Handling Stage compared to the Isolation Stage because of cumulative effects of handling and time of pup isolation from the nest. At the Isolation Stage, the call rate (calls/s) was higher from 10 to 18 days of age, whereas both the maximum amplitude frequency and power quartiles of joint calls were lower than at the Handling Stage from 20 to 32 days of age. At the same time, in audible (<20 kHz) vocalizations of a wide range of mammalian species, both the higher call rate and the upward shift of the maximum amplitude frequency and power quartiles indicate the discomfort-related increase of negative emotional arousal. We discuss the advantages of the method of joint calls for express-analyses of power variables for large sequences of ultrasonic vocalizations of complex acoustic structure during experimental trials.