Population dynamics of Rattus argentiventer, Rattus losea, and Rattus rattus inhabiting a mixed-farming system in the Red River Delta, Vietnam

Rodent pests cause significant damage to lowland irrigated rice crops in the Red River Delta of northern Vietnam. Data from a 4-year study were examined to look at the population dynamics of the ricefield rat, Rattus argentiventer (representing 50% of captures), the lesser ricefield rat, Rattus losea (30% of captures), and the black rat, Rattus rattus complex (9% of captures) that inhabit the irrigated mixed-cropping system. We tested the hypothesis that these rodent species were breeding in response to the availability of high-quality food provided by crops rather than in response to rainfall. The abundance of rodents fluctuated annually, with a main peak following the spring rice crop, and a secondary peak following the summer rice crop. There was a strong relationship between the monthly abundance of rats and rainfall, but a weak relationship between monthly rates of increase and rainfall. There were distinct peaks in breeding activity during the reproductive stages of the rice crops suggesting that changes in crop stages were more important than rainfall in this seasonal, but irrigated agroecosystem. The modal litter size for R. argentiventer was 8 (mean of 8.67±0.20 SE, range 2–16), where the mode for R. losea, was 7 (mean of 7.32±0.15 SE, range 3–14). Management of these species needs to be conducted prior to the onset of the main breeding seasons.     

Chronology of Rattus muelleri Jentink

Metrical characteristics of Mueller's rats of precisely known age have not previously been available. Observations on the growth and sexual maturation of laboratory-reared individuals have been made and regressions calculated for the more useful characters. The equations so obtained are applied to published data of other workers.     

屋顶鼠首次在新疆发现

正屋顶鼠(Rattus rattus)又称黑家鼠,据说原产于印度半岛(Pavlinov 2003,马勇等2012)。由于该鼠擅长爬高攀登,随着贸易往来的交通工具传播到了亚洲各国。据文献记述,1958年随着船舶贸易的往来,在大连口岸地区繁殖蔓延(张宝森等1999),1996年在广西防城口岸被发现(谭勇等1997),2011年传入四川成都市,如今江苏、浙江、江西、湖北、贵州、云南、福建、广东、广西、台湾、海南、四川、西藏等省(自治区)均有分布(杨再学2015)。新疆为大陆性气候,历史上地广人稀,啮齿动物种类繁多,但家栖鼠种长期仅见小家鼠(Mus     

Identifying Rattus species using mitochondrial DNA

In recent years, research has shown that geographical variation in mitochondrial DNA of commensal rats provides a strong signal of human dispersal and migration. However, interpretation of genetic variation is complicated by the presence of multiple species of Rattus especially in Island Southeast Asia, by the occurrence of some of these Rattus sp. as subfossils in archaeological and natural sites, and by the difficulty of osteological identification of these remains. Amplification of DNA from ancient sources usually yields only small fragments (～200 bp). We assessed whether we could identify Rattus sp. reliably with DNA barcoding using cytochrome oxidase I (COI) sequences, or tree‐based methods using D‐loop, cytochrome b and COI sequences. Species forming well‐differentiated clades in a molecular phylogeny were accurately identified by both methods, even when we used short DNA fragments. Identification was less accurate for paraphyletic and polyphyletic species. We suggest that taxonomic revisions that recognize cryptic or polytypic species will lead to even greater accuracy of DNA‐based identification methods.     

云南省34个县市黄胸鼠和褐家鼠体表寄生蚤调查

目的调查云南省黄胸鼠Rattus flavipectus和褐家鼠R.norvegicus体表寄生蚤的感染情况,为云南省鼠疫防控提供科学依据。方法 2012年7月—2013年11月,在云南省34个县市随机选取采样点,笼捕法采集黄胸鼠和褐家鼠,收集并鉴定体表寄生蚤,统计宿主和蚤类物种组成、染蚤率、蚤指数,并根据蚤种组成进行分层聚类。结果采集鼠类842只,其中黄胸鼠714只、褐家鼠128只;共检获体表寄生蚤3227匹,涵盖10个已知蚤种,其中,印鼠客蚤Xenopsylla cheopis和缓慢细蚤Leptopsylla segnis为优势物种。黄胸鼠和褐家鼠的染蚤率分别为48.88%和53.91%,2种鼠的总体蚤指数为3.83匹/只,其中有16个县市的印鼠客蚤指数>1。聚类分析将所有样点聚成3大支系:A支系印鼠客蚤占优势,主要分布于云南省南部地区;B支系优势种不明显或具有其他蚤种,分布于云南省中部地区;C支系缓慢细蚤占优势,分布于云南省北部地区。结论印鼠客蚤和缓慢细蚤是云南省主要蚤种,在接近半数地区印鼠客蚤指数>1,防疫形势非常严峻。云南省黄胸鼠和褐家鼠体表蚤区系组成具有一定的地带性,其中南部地区为印鼠客蚤优势分布区,可视为媒介监测和防控的重点区域。     

The hyoid complex of Rattus rattus rufescens

The hyoid apparatus of the rat consists of an anteroposterior compressed and somewhat arched basihyal, the small anterior cornua and the more prominent posterior cornua. The ceratohyal is the only movably articulated element of the anterior cornu and is generally lost during the normal methods of preparing skeleton. The absence of stylohyal has resulted in modifications in the origins and insertions of Mm. stylohyoideus, styloglossus, and stylopharyngeus. The study of the hyoid region of rats, gerbils and squirrels supports the view that the muroid rodents have originated from the more generalized squirrel-like forms.     

Carriage of Clostridium difficile by Wild Urban Norway Rats (Rattus norvegicus) and Black Rats (Rattus rattus)

Clostridium difficile is an important cause of enteric infections in humans. Recently, concerns have been raised regarding whether animals could be a source of C. difficile spores. Although colonization has been identified in a number of domestic species, the ability of commensal pests to serve as a reservoir for C. difficile has not been well investigated. The objective of this study was to determine whether urban rats (Rattus spp.) from Vancouver, Canada, carry C. difficile. Clostridium difficile was isolated from the colon contents of trapped rats and was characterized using ribotyping, toxinotyping, and toxin gene identification. Generalized linear mixed models and spatial analysis were used to characterize the ecology of C. difficile in rats. Clostridium difficile was isolated from 95 of 724 (13.1%) rats, although prevalence differed from 0% to 46.7% among city blocks. The odds of being C. difficile positive decreased with increasing weight (odds ratio [OR], 0.67; 95% confidence interval [CI], 0.53 to 0.87), suggesting that carriage is more common in younger animals. The strains isolated included 9 ribotypes that matched recognized international designations, 5 identified by our laboratory in previous studies, and 21 “novel” ribotypes. Some strains were clustered geographically; however, the majority were dispersed throughout the study area, supporting environmental sources of exposure and widespread environmental contamination with a variety of C. difficile strains. Given that urban rats are the source of a number of other pathogens responsible for human morbidity and mortality, the potential for rats to be a source of C. difficile for humans deserves further consideration.     

Biochemical differentiation among karyotypic forms of Australian Rattus

Isozyme electrophoresis of up to 55 loci, and microcomplement fixation of albumin were used to assess the extent of structural gene divergence among karyotypic forms of Australian Rattus. The results show that the Australian Rattus are monophyletic with respect to R. rattus or R. norvegicus. Within the Australian Rattus, rates of chromosomal evolution have varied enormously, the highest rates being found among members of the R. sordidus group, where extensive chromosomal repatterning has occurred with little or no structural gene divergence.     

Nucleotide sequence variants of Rattus norvegicus mitochondrial DNA

The mitochondrial DNA (mtDNA) molecules of different albino, domesticated rats (Rattus norvegicus) of the SASCO colony are of two kinds (SASCO-1 and SASCO-2) in regard to their sensitivity at certain sites to a number of restriction enzymes. MtDNA molecules from Utah wild R. norvegicus (Wild-UT) have sensitivities to restriction enzymes which differ at some sites from either SASCO-1 or SASCO-2 mtDNA molecules. Four single nucleotide differences were found among the HindIII F fragments (169 nucleotides) of SASCO-1, SASCO-2, and Wild-UT mtDNAs. Arguments are presented in favor of the interpretation that each variant nucleotide is the third nucleotide of the codon containing it, and that none of the four differences would result in a difference in the respective amino acid translated.Dedicated to Professor W. Beermann on the occasion of his 60th birthday     

大鼠肝脏半乳糖凝聚素-3 cDNA分子多样性分析

半乳糖凝聚素-3(Galectin-3,Gal-3)是一种多功能蛋白,参与机体内的多种生命活动过程。为分析大鼠Rattus norvegicus gal-3 c DNA分子多样性,在分析Gen Bank注册的大鼠gal-3 c DNA序列的同时,从三只不同大鼠个体的肝脏第一链c DNA,共计9个独立实验中克隆gal-3开放阅读框OFR(Open reading frame)。分析结果表明,在已注册的序列中存在1个单核苷酸多态性(Single nucleotide polymorphism,SNP)。本实验从1-3号大鼠肝脏分别获得118、95和120个克隆,新发现1处缺失和5处SNP,共克隆17个不同的gal-3 ORF,其中仅1个克隆与已报告大鼠gal-3 c DNA的ORF完全相同。从1号和3号个体肝脏中分别克隆11和14个不同的gal-3 ORF,揭示大鼠gal-3 c DNA存在个体水平的分子多样性。     

Isolation and characterization of microsatellites in Rattus rattus

We isolated and characterized 10 microsatellite loci in the black rat Rattus rattus (Muridae, Rodentia), a widespread invasive species largely known to cause serious problems in agriculture and human health. Polymorphism was studied in two populations, one from Madagascar and one from Senegal. It ranged from three to 12 alleles in Madagascar, and from two to five alleles in Senegal. Together with the loci previously adapted from Rattus norvegicus, this set of markers should allow the conduct of thorough studies on the genetic structure of natural populations of R. rattus.     

褐家鼠线粒体DNA遗传多态性的研究

通过碱变性法提取线粒体ＤＮＡ,用地高辛标记的探针Ｓｏｕｔｈｅｒｎ杂交限制性酶切多态性（ＲＦＬＰ）分析,研究中国家鼠Ｒａｔｔｕｓｎｏｒｖｅｇｉｃｕｓ遗传多态性。采用ＡｐａⅠ、ＡｖａⅠ、ＢａｎＨＩ、ＢｃｌⅠ、ＢｇｌⅠ、ＣｌａⅠ、ＥｃｏＲⅠ、ＥｃｏＲⅤ、ｈｉｎｄⅢ、ＰｖａⅡ、ＳｃａⅠ和ＸｂａⅠ等１２种限制性内切酶分析来自我国８个地区２６只褐家鼠的线粒体ＤＮＡ,共检出２０种限制性态型和１１种ｍｔＤＮＡ单倍