Muridae Species Research Articles

COMUNIDADES DE ROEDORES DE CULTIVOS DE SORGO EN LA PROVINCIA DE CÓRDOBA Y SU POSIBLE VINCULACIÓN CON LA FIEBRE HEMORRÁGICA ARGENTINA

The composition of rodent communities in fields dedicated to sorghum culture was studied in seven sites situated along two transects about 500 km long, in the SE of Córdoba Province (Argentina). Four of the sites are in the endemic area of ArgentineHemorrhagic Fever and the other three in the marginal area, free of Junin virus. The animáis were trapped during a short period in May and June, 1977. Eight Crieetidae (Calomys musculinus, Akodon azarae, Calomys laucha, Oligoryzomys flavescens, Cabreramys benefactus, Akodon dolores, Graomys griseoflavus y Calomys callosus) and one Muridae species (Mus musculus) were obtained. Comparative analysis of the species composition of the communities has been performed by using the Mountford Índex.Total number of specimens from Calomys plus Akodon represented, in all the samples, more than 80%. The most abundant species in six out of seven samples was C. musculinus, the most important reservoir of Junin virus. The structure of this species populationswas very similar for most of the endemic and marginal areas.

Food resources and competition rather than eco-geographic rules explain trait variations in two contrasting rat species: Implications for future climate change

Understanding how morphological traits are influenced by temperature, resource availability and competition is critical for predicting future ecosystem resilience to climate change. Here we tested the effects of biotic and abiotic factors, on the morphology of two contrasting Muridae species (Chinese white-bellied rats Niviventer confucianus [n = 565; 57.1 g] and Edwards's long-tailed giant rats Leopoldamys edwardsi [n = 45; 459.5 g]) in relation to Bergmann’s, Allen’s, Hesse’s and Geist’s eco-geographical rules along a 2900-m elevational gradient. Specifically, we tested the “body size threshold” theory, which posits that animals heavier than 0.16 kg are more likely to follow Bergmann’s rule. We measured body length and mass, appendage lengths and heart mass for 610 adult specimens from 115 localities, and used principal components analysis to quantify food resource availability. Linear mixed models were employed to test these eco-geographical rules, along with the effects of associated biotic and abiotic factors. We found that for N. confucianus (< 0.16 kg), colder temperatures were associated with smaller body-size, contrary to Bergmann’s rule, and with greater interspecific competition and food abundance (supporting Geist’s rule). There was no support for Allen's rule, except for a contrary effect on snout length among females; however, greater intraspecific competition and lesser food abundance were associated with shorter snout length, supporting Geist’s rule. Heart size increased with colder temperatures, but only among females, partly supporting Hesse’s rule, and decreased with greater intraspecific competition for both sexes. L. edwardsi (> 0.16 kg) did not conform with any eco-geographic rules, and so we found no support for the “body size threshold” theory. Our study proposes that food resource abundance and inter- and intraspecific competition mediated variations in morphological traits in these rodent species to a greater extent than any reduction in temperature alone, giving little support for ecogeographical rule effects. We interpret that where food supply can meet energetic demands, even under colder conditions, then any selective pressure for thermal/energy efficiency through larger body size and shorter appendages will be alleviated. Considering the full range of inter-related factors that are affected by temperature, rather than just the bio-physics of heat loss, is important to better predict future climate change responses.

Comparative Morphology of the Male Genitalia of Japanese Muroidea Species

We examined the morphology of the male genitalia of six Muridae and five Cricetidae in the Muroidea focusing on the medial and lateral bacular mounds, as well as their ossification patterns to discuss the diversity and the movement mechanism of the trident structure. All examined species possessed a medial bacular mound and two lateral bacular mounds, which collectively formed a trident structure. In the Muridae species, the medial bacular mound was ossified or consisted of cartilage, while the lateral bacular mounds were composed of soft tissue. By contrast, both the medial and lateral bacular mounds were ossified in the Cricetidae species. Among the Muridae species, the medial bacular mound was well developed, and the lateral bacular mounds were small in Mus and Micromys species while the medial bacular mound was highly developed, and the lateral bacular mounds were developed in Apodemus speciosus. Different combinations of developmental characteristics of the medial and lateral bacular mounds produced variation in the glans penis morphology. Histological examination of A. speciosus and Craseomys rufocanus suggested that the movement of the lateral bacular mounds was driven by blood flowing into the cavernous space, and the movement increases the cross-sectional area of the glans penis.

Diet composition of the Javan mongoose (Urva javanica) within two forests across a karst landscape, on Java, Indonesia

We investigated the diet composition and possible ecological role played by the Javan mongoose in Java. During the 2018 dry season, fecal samples were collected from an old-growth forest (Wonosadi; n = 49) and a restored forest (Wanagama; n = 41), located in southern Yogyakarta, which were analyzed to identify food items at the family level. The frequency of occurrence of diet items was used for data comparison. Overall, the Javan mongoose fed more frequently on vertebrates of family Muridae, Phasianidae, and Colubridae as compared to invertebrate and other taxa. No significant difference was discovered in the diet composition between Wonosadi and Wanagama regions (Mantel–Haenszel test: χ2 = 1.17; P > 0.05). In line with other studies, the findings here indicate the predation of pests (Muridae species) and birds by the Javan mongoose. The findings also suggest that the Javan mongoose potentially controls the rat population in these regions, however, they might have an impact on the local biodiversity as they raid poultries and predate some ecologically significant vertebrates and invertebrates.

Radiocesium concentration ratios and radiation dose to wild rodents in Fukushima Prefecture

Radiocesium was dispersed from the Fukushima Dai-ichi disaster in March 2011, causing comparatively high radioactive contamination in nearby environments. Radionuclide concentrations in wild rodents (Apodemus argenteus, and Apodemus speciosus) within these areas were monitored from 2012 to 2016. However, whole-organism to soil transfer parameters (i.e., concentration ratio, CRwo-soil) for wild rodents at Fukushima were not determined and hence were lacking from the international transfer databases. We augmented the 2012–2016 data by collecting soil activity concentrations (Bq kg−1, dry mass) from five rodent sampling sites in Fukushima Prefecture, and developed corresponding CRwo-soil values for radiocesium (134Cs and 137Cs) based on rodent radioactivity concentrations (Bq kg−1, fresh mass). The CRwo-soil were added to the Wildlife Transfer Database (WTD; http://www.wildlifetransferdatabase.org/), supporting the development of the International Commission on Radiological Protection's (ICRP) environmental protection framework, and increasing the WTD from 84 to 477 entries for cesium and Muridae (‘Reference Rat’). Significant variation occurred in CRwo-soil values between study sites within Fukushima Prefecture. The geometric mean CRwo-soil, in this paper, was higher than that reported for Muridae species for Chernobyl.Radiocaesium absorbed dose rates were also estimated for wild rodents inhabiting the five Fukushima study sites and ranged from 1.3 to 33 μGy h−1. Absorbed dose rates decreased by a factor of two from 2012 to 2016. Dose rates in highly contaminated areas were within the ICRP derived consideration reference level for Reference Rat (0.1–1 mGy d−1), suggesting the possible occurrence of deleterious effects and need for radiological effect studies in the Fukushima area.

Ancient origin and complex evolution of porcine endogenous retroviruses

Porcine endogenous retroviruses (PERVs) are proviruses that have medical value in xenotransplantation. However, the evolutionary process leading to the generation of modern PERVs is not well understood. In this study, we in silico mined 14 pig genomes and other available 304 mammalian genomes, which led to the documentation of 185 full-length PERVs or PERV-like sequences. Notably, we found that lesser Egyptian jerboa (Jaculus jaculus), rock hyrax (Procavia capensis) and eight Muridae species all harbored ancestral PERV-like sequences, indicative of ancient cross-species transmission events from none-porcine species to pigs. We also revealed that 11 genomic rearrangement events were mediated via PERVs, during the process of porcine evolution. In conclusion, these new findings help us to understand the complex evolution of the modern PERVs.

Molecular identification of temperate Cricetidae and Muridae rodent species using fecal samples collected in a natural habitat

Molecular species identification from biological material collected at field sites has become an established ecological tool. However, extracting and amplifying DNA from degraded field samples, such as prey remains and feces that have been exposed to the elements, remains a challenge and costly. We collected 115 fecal samples of unknown small mammals, resembling fecal droppings of voles and mice (i.e., Cricetidae and Muridae), from a salt marsh in The Netherlands. We modified a previously published protocol into a relatively low-cost method with a PCR success of 95%. We demonstrate that species identification is possible for both Cricetidae and Muridae species using fecal samples of unknown age deposited in the field. For 90 samples, sequences of the variable control region in the mitochondrial genome were obtained and compared to published DNA sequences of small mammals occurring in north European salt marshes. A single sample, probably environmentally contaminated, appeared as Sus scrofa (n = 1). We positively identified house mouse Mus musculus, being the positive control (n = 1), and common vole Microtus arvalis (n = 88). In 81 sequences of 251 nt without ambiguous bases, ten haplotypes were present. These haplotypes, representing the central lineage of the western subspecies M. arvalis arvalis, were separated by 20 mutations from published control region haplotypes of the western European lineages sampled in France. Unlike earlier studies of cytochrome b variation in coastal European populations, we did not find indications of recent purging of genetic variation in our study area.

Identification of Muridae Species and Their Food Resources Using Dna Barcoding in Cat Tien National Park, Vietnam

Abstract. Field surveys of species in the family Muridae and their food resources were conducted in Cat Tien National Park, Vietnam in March 2011 and March and September 2012. Species were identified by DNA barcoding using polymorphic mitochondrial DNA sequences (COI, Cyt b, and D-loop) and external morphology. A total of four species, Maxomys surifer, Niviventer fulvescens, N. bukit, and Rattus sp. were identified. In order to identify which food resources were utilized by these species in the study area, total DNA was extracted from the gastric contents of the collected individuals. Sequence fragments of the chloroplast rbcL and the mitochondrial COI genes were amplified by PCR from the gastric contents and used to identify plant and animal food resources, respectively. We detected 34 plant families and seven animal orders by the homology search using the BLAST algorithm.

The complete mitochondrial genome of the Leopoldamys edwardsi (Rodentia: Muridae)

The complete mitochondrial genome of L. edwardsi was first sequenced and characterized. The genome was 16,284 bases in length and the composition and arrangement of its genes are analogous to most other rodents. The nucleotide sequence date of 12 heavy-strand protein-coding genes of L. edwardsi and other 26 Muridae species were used for phylogenetic analyses. Trees constructed using Maximum Likelihood, Neighbor Joining and Minimum Evolution demonstrated that L. edwardsi was closer to the genus Niviventer than Rattus. Combing previous research, it suggests that Edward’s long-tailed rat is more suitable to be classified into genus Leopoldamys and named as Leopoldamys edwardsi. This study suggested that R. edwardsi is inappropriate for the other name of L. edwardsi.

Habitat-specific shaping of proliferation and neuronal differentiation in adult hippocampal neurogenesis of wild rodents

Daily life of wild mammals is characterized by a multitude of attractive and aversive stimuli. The hippocampus processes complex polymodal information associated with such stimuli and mediates adequate behavioral responses. How newly generated hippocampal neurons in wild animals contribute to hippocampal function is still a subject of debate. Here, we test the relationship between adult hippocampal neurogenesis (AHN) and habitat types. To this end, we compare wild Muridae species of southern Africa [Namaqua rock mouse (Micaelamys namaquensis), red veld rat (Aethomys chrysophilus), highveld gerbil (Tatera brantsii), and spiny mouse (Acomys spinosissimus)] with data from wild European Muridae [long-tailed wood mice (Apodemus sylvaticus), pygmy field mice (Apodemus microps), yellow-necked wood mice (Apodemus flavicollis), and house mice (Mus musculus domesticus)] from previous studies. The pattern of neurogenesis, expressed in normalized numbers of Ki67- and Doublecortin(DCX)-positive cells to total granule cells (GCs), is similar for the species from a southern African habitat. However, we found low proliferation, but high neuronal differentiation in rodents from the southern African habitat compared to rodents from the European environment. Within the African rodents, we observe additional regulatory and morphological traits in the hippocampus. Namaqua rock mice with previous pregnancies showed lower AHN compared to males and nulliparous females. The phylogenetically closely related species (Namaqua rock mouse and red veld rat) show a CA4, which is not usually observed in murine rodents. The specific features of the southern environment that may be associated with the high number of young neurons in African rodents still remain to be elucidated. This study provides the first evidence that a habitat can shape adult neurogenesis in rodents across phylogenetic groups.

Chromosome homology between mouse and three Muridae species, Millardia meltada, Acomys dimidiatus and Micromys minutus, and conserved chromosome segments in murid karyotypes

Comparative chromosome painting with mouse (Mus musculus, MMU) chromosome-specific DNA probes was performed for three Muridae species, the Indian soft-furred field rat (Millardia meltada), the spiny mouse (Acomys dimidiatus) and the harvest mouse (Micromys minutus). All probes except for the Y probe were successfully hybridized to the chromosomes of all species, and homologous chromosome segments between mouse and the three species were identified at the molecular level. Comparison of our data with the published data of six other genera (Mus, Rattus, Apodemus, Otomys, Rhabdomys and Cricetulus) of the Muridae suggested that the associations MMU1b/17a, 2b/13a, 5b/11a, 7/19, 10b/17b, 10c/17c, 11b/16a, 12/17d and 13b/15, and the single painted chromosomes and chromosome segments MMU3, 4, 5a, 8a, 8b, 16b, 18 and X were probably contained by the ancestral karyotype of the Muridae, and have been strongly conserved throughout murid evolution.

Fruit visitation patterns of small mammals on the forest floor in a tropical seasonal forest of Thailand

The fruit visitation patterns of small mammals were investigated by camera trappings on the forest floor in a tropical seasonal forest of Thailand. A total of 3,165 visits were recorded for seven small mammal species. The four Muridae species, Rattus remotus, Niviventer fulvescens, Leopoldamys sabanus and Maxomys surifer, all of which were nocturnal, were almost completely temporally segregated from the tree shrew, Tupaia belangeri, and the two squirrels, Callosciurus finlaysonii and Menetes berdmorei, which were diurnal or crepuscular. We suggest that the temporal segregation reduced the interference competition between the four Muridae species and the tree shrew or squirrel for fruits on the forest floor. In addition, the visitation patterns for fruit species differed among the four Muridae species and between the tree shrew and the two squirrels, suggesting that the variation in the visitation patterns for fruit species helped to facilitate coexistence among these species. In contrast, the two squirrels were similar in their visitation patterns, both temporally and in their choice of fruit species.

The Muridae glyceraldehyde-3-phosphate dehydrogenase family

Although only one gene is known to be functional, numerous glyceraldehyde-3-phosphate dehydrogenase (GAPDH) related sequences are scattered throughout Mus musculus and Rattus rattus genomes. In this report we show that: (1) GAPDH pseudogenes are repeated to comparable extents, at least 400 copies, in 12 other Muridae species; (2) the complete, or nearly so, sequence of GAPDH messenger RNA is amplified, and a high proportion, if not all of these copies, are intronless; (3) GAPDH pseudogenes are preferentially located in heavily methylated and DNAse I-insensitive regions of chromatin; and (4) the presence of atypical GAPDH-related mRNAs in different cellular contexts raises the possibility that more than one GAPDH gene is transcribed.

Topografia linki, linienie i struktura sierści u badylarki

An examination was made of the moult patterns, moulting and the structure of the fur based on 304 pelts of harvest mouse, Micromys minutus (Pallas, 1778) obtained from the western part of Central Finland during the period September-January. This material included 150 individuals in the process of moulting. Zbadano cechy linki, linienie i strukturę sierści u 304 badylarek, Micromys minutus (Pallas, 1778), analizując skórki uzyskane z odłowów prowadzonych w okresie IX-I we wschodniej części centralnej Finlandii.

A 'posterior ring' in the spermatozoa of species of Muridae.

Summary. An examination of surface replicas of spermatozoa from five Muridae species has confirmed the existence of a 'posterior ring' encircling the nucleus. The post-acrosomal surface is subdivided by this ring into two areas, the post-nuclear cap and a smaller more distal region which, in these preparations, has a characteristic topography.