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.     

Comparative studies on release of enzymes from platelets during blood clotting in Rattus rattus flavitecus and Rattus norvegicus (author's transl)

Increase of lactate dehydrogenase (EC 1.1.1.28) and creatine kinase (EC 2.7.3.2) in serum and plasma level during blood clotting was compared in R. rattus flavitectus (black rat) and R. norvegicus (albino rat). Both the enzyme level increased by the release from platelets in process of clotting in rat as previously described (Emori T., Takahashi M. and Nagase S. (1978) Exp. Animals, 27, 167), but the change in black rat was very slight. Owing to search for the reason to prove the difference in this phenomenon, physiological and chemical properties of blood from both the animals were compared, and it was demonstrated that the content of plasma fibrinogen in black rat is higher than that in albino rat, while the platelet number contained in each ml of blood and the enzyme activities in each platelet are not different between them. The analysis of the membrane proteins from platelets of both the animals by SDS-polyacrylamide gel electrophoresis showed that the fractional value of glycoproteins was found to be different between them.     

Ag-NOR chromosomal association patterns in Rattus rattus (Rafinesque, 1814) and Rattus norvegicus (Berkenhout, 1796) from the southern Iberian peninsula

A high frequency of satellite association phenomena in a number of specimens of Rattus rattus and R. norvegicus, captured on the coastal fringe of Málaga province (Southern Spain), was found. Only Ag-NOR bearing chromosomes participated in associations in both species. R. rattus is characterized by 14/18 heterologous and R. norvegicus by 5/5 and 13/13 homologous association types.     

Shifts in an invasive rodent community favoring Black rats (Rattus rattus) following restoration of native forest

One potential, unintended ecological consequence accompanying forest restoration is a shift in invasive animal populations, potentially impacting conservation targets. Eighteen years after initial restoration (ungulate exclusion, invasive plant control, and out planting native species) at a 4 ha site on Maui, Hawai'i, we compared invasive rodent communities in a restored native dry forest and adjacent non‐native grassland. Quarterly for 1 year, we trapped rodents on three replicate transects (107 rodent traps) in each habitat type for three consecutive nights. While repeated trapping may have reduced the rat (Black rat, Rattus rattus) population in the forest, it did not appear to reduce the mouse (House mouse, Mus musculus) population in the grassland. In unrestored grassland, mouse captures outnumbered rat captures 220:1, with mice averaging 54.9 indiv./night versus rats averaging 0.25 indiv./night. In contrast, in restored native forest, rat captures outnumbered mouse captures by nearly 5:1, averaging 9.0 indiv./night versus 1.9 indiv./night for mice. Therefore, relatively recent native forest restoration increased Black rat abundance and also increased their total biomass in the restored ecosystem 36‐fold while reducing House mouse biomass 35‐fold. Such a community shift is worrisome because Black rats pose a much greater threat than do mice to native birds and plants, perhaps especially to large‐seeded tree species. Land managers should be aware that forest restoration (i.e. converting grassland to native forest) can invoke shifts in invasive rodent populations, potentially favoring Black rats. Without intervention, this shift may pose risks for intended conservation targets and modify future forest restoration trajectories.     

Synaptic behaviour of some structural and numerical chromosome anomalies in female and male rats (Rattus norvegicus)

The processes of synapsis and synaptic adjustment have been detected in some structural and numerical anomalies in two female rat foetuses and in one male rat in the course of a study on X-ray genotoxicity. The synaptic characteristics and adjustment of one pericentric inversion and a deletion have been analysed by electron microscopy in synaptonemal complex spreads from two female foetuses, and the synaptic behaviour of a trisomy has been studied in a testicular biopsy from an adult male. In a large proportion (from 50% to 90%) of the analysed cells, the abnormal meiotic configuration could not be detected either because the anomaly was present in mosaic from trisomy or because synaptic adjustment had already taken place (inversion) or as result of a combination of two of the above (deletion).     

Elimination of some enteroviruses in the excrements of experimentally infected rats (Rattus norvegicus) and gulls (Larus ridibundus)

Young rats of both sexes, weight 150-170 g, the first laboratory progeny of captured wild parent pairs, were used throughout this experiment. Rats in two experimental groups comprising a total of 34 animals were infected orally with type 2 poliovirus vaccine strain given in each group at doses of 500, 5000 or 50,000 TCD50. In the first experiment, the presence of poliovirus in rat excrements was detectable irregularly till day 13, in the second experiment till day 2 after infection. Small quantities of virus were also detectable from the colon and cecum wall, exceptionally from the mesenteric lymph node. The third experiment included 8 rats orally infected with 5,000 TCD50 of echovirus 30; at the lower dose of virus all excrement samples were culture-negative, at the higher dose the positive virus recovery was recorded in 3 animals one day after infection. Analogous experiments in the fifth group of rats orally infected with 5,000 TCD50 or 50,000 TCD50 of enterovirus 71 yielded much the same results; organs of further 6 animals infected intranasally with 5,000 TCD50 of this virus were culture-negative and no virus-related changes could be histologically demonstrated in these animals. The second part of this study included the experiments conducted on 17 young Larus gulls bred in the laboratory from eggs collected in a colony of free living birds. Groups of these gulls were orally infected with 500 or 5,000 TCD50 of one of the following viruses: type 1 poliovirus vaccine strain, type 3 poliovirus vaccine strain, echovirus 30, enterovirus 71 and coxsackievirus B4. All samples of gull excrements collected till day 7 or 20 postinfection were culture-negative. These results suggest that wild rats may play some role in the spread of human enteroviruses in the environment, but no such role could be demonstrated in the Larus gull.     

Identification and characterization of some serum proteins of the laboratory rat (Rattus norvegicus) by crossed immunoelectrophoresis.

Rat (Rattus norvegicus) serum proteins were examined by means of crossed immunoelectrophoresis. We have performed the topographic characterization of prealbumins, albumin, orosomucoid, glycoprotein of Darcy, alpha-macroglobulins, haptoglobin, hemopexin, transferrin and IgG. There are several differences in rat serum in comparison to human serum. This applies, for example, to prealbunins and to Darcy's glycoprotein. The behaviour of these fractions in different conditions is discussed in more detail.     

Electron microscopy and microcalorimetry of the postnatal rat heart (Rattus norvegicus)

The interplay of ultrastructure and tissue metabolism was examined in neonatal, infant and adult rat hearts by electron microscopy and microcalorimetry. Morphometry was used to determine parameters of oxygen diffusion capacity (distance between capillaries and mitochondria, capillary surface density) and oxidative metabolic capacity (mitochondrial volume fraction). Thin slices and large samples of living tissue were examined calorimetrically to quantify aerobic metabolism and ischemia tolerance, respectively. After birth, rat hearts grow in parallel to body mass and show characteristics of cellular hypertrophy. Capillary surface density increases from neonatal to infant rats, and decreases to an intermediate value in adult rats. The distance between capillaries and mitochondria shows no significant changes throughout postnatal development. Mitochondrial volume fraction increases continuously until adulthood. The specific aerobic tissue metabolic rate is higher in the neonatal than in the infant and adult rat. However, the ischemic decline in metabolic rate is much slower in the neonatal rat, reflecting an elevated hypoxia tolerance. In conclusion, the neonatal rat heart exhibits a high metabolic rate despite a low mitochondrial volume fraction. The subsequent structural rearrangements can be interpreted as long-term adaptations to the increased postnatal workload and may contribute to the progressive loss of hypoxia tolerance.     

Palmar and plantar pads and flexion creases of the rat (Rattus norvegicus)

The recent detection of dermal ridge configurations on the volar pads of the rat (Rattus norvegicus) has created opportunities for experimental studies of dermatoglyphics. In the present work, the palmar and plantar surfaces of the rat were studied to establish the feasibility of comparative rat and human dermatoglyphic investigations. The studied features included the volar pads and flexion creases. The number and location of the palmar and plantar pads in the rat were found to be similar to those of humans. The exception was a previously unrecognized small pad on the palms and soles of the rat, located on the radial and tibial side, respectively, of the proximal component of the first interdigital pad. This pad has no parallel in human embryos. Rats were found to have flexion creases in the non-pad areas between the neighboring pads, similar in location and appearance to those of humans. Unlike humans, however, rats also have boundary creases, separating the pad and non-pad areas. The marked similarities in the morphology of the volar areas between rats and humans make the rat ideally suitable for experimental studies of dermatoglyphics and flexion creases. Results of such studies should be applicable to human developmental dermatoglyphics, including those pertaining to medical disorders. © 1994 Wiley-Liss, Inc.     

Influence of jute (Corchorus olitorius) seed protein enriched diet on some enzymes and liver lipids of albino rats (Rattus norvegicus)

The effect of protein, isolated from Jute (Corchorus olitorius) seed was studied upon albino rats with respect to some of their serum, liver and intestinal enzymes and liver lipids. An increase in the body weight (including the weight of the liver) was noted in test animals after feeding with a Jute seed protein enriched diet. It was also observed that AST, ALT and total lipid of liver increased significantly whereas AST and ALT of serum were decreased. An increase in the concentration of lipids in the liver was found and this may be due to excess of the seed protein in the diet. An overall observation reveals that there is slight fatty infiltration in the liver of test animals.     

An investigation of playful behaviour in Rattus norvegicus and Mus musculus (Mammalia)

The playful behaviour of laboratory rats ( Rattus norvegicus ) was investigated in litters of five individuals with the mother present; parallel observations were made on mice ( Mus musculus ). Seven mixed litters containing four young rats and a young mouse fostered at birth were also observed.
Solitary play was recorded in both species and took a similar form but social play was only observed in rats. In rats, solitary play frequently preceeded social play.
The behavioural elements involved in the social play of Rattus norvegicus were described, and the majority of these were the playful equivalent of adult agonistic behaviour elements. These social play elements were found to be organized into definite sequences which differed from those of adult aggression. Each behavioural element was found to act as a social releaser.
Young mice did not respond playfully to social play from a rat litter mate; mice were less attractive to rats as playmates in comparison with fellow rats.     

Metabolism of fluoroacetate in the skink (Tiliqua rugosa) and the rat (Rattus norvegicus)

Administration of 100 mg sodium fluoroacetate (compound 1080) per kilogram body weight to T. rugosa resulted in a 3.4-fold increase in plasma citrate levels 48 h after dosing while administration of 3 mg sodium fluoroacetate per kilogram body weight to R. norvegicus produced a fivefold increase in plasma citrate levels within 4 h. Administration of 300 mg sodium fluoroacetate per kilogram body weight reduced the oxygen consumption of the skink by between 2.5 and 11% while in the rat, 2 mg sodium fluoroacetate per kilogram body weight reduced oxygen consumption by between 28 and 57%. Aconitate hydratase activity in extracts of liver acetone powders from T. rugosa was less inhibited by (-)erythrofluorocitrate (Ki: 0.065 mM) than that in extracts derived from R. norvegicus (Ki: 0.026 mM). The rate of defluorination of fluoroacetate in erythrocytes and in extracts of liver acetone powders of T. rugosa was 8- and 4.5-fold greater, respectively, than that found in similar preparations from R. norvegicus. A rapid rate of defluorination together with a low reliance on aerobic respiration favoured detoxification of fluoroacetate in T. rugosa rather than its conversion into fluorocitrate. Though defluorination in this species helped to minimize the immediate effects of fluoroacetate on aerobic respiration, it resulted in rapid depletion of liver glutathione levels.     

Purification of glucose‐6‐phosphate dehydrogenase from rat (Rattus norvegicus) erythrocytes and inhibition effects of some metal ions on enzyme activity

Glucose‐6‐phosphate dehydrogenase (G6PD) is the first enzyme on which the pentose phosphate pathway was checked. In this study, purification of a G6PD enzyme was carried out by using rat erythrocytes with a specific activity of 13.7 EU/mg and a yield of 67.7 and 155.6‐fold by using 2′,5′‐ADP Sepharose‐4B affinity column chromatography. For the purpose of identifying the purity of enzyme and molecular mass of the subunit, a sodium dodecyl sulfate‐polyacrylamide gel electrophoresis was carried out. The molecular mass of subunit was calculated 56.5 kDa approximately. Then, an investigation was carried out regarding the inhibitory effects caused by various metal ions (Fe²⁺, Pb²⁺, Cd²⁺, Ag⁺, and Zn²⁺) on G6PD enzyme activities, as per Beutler method at 340 nm under in vitro conditions. Lineweaver–Burk diagrams were used for estimation of the IC₅₀ and K_i values for the metals. K_i values for Pb⁺², Cd⁺², Ag⁺, and Zn⁺² were 113.3, 215.2, 19.4, and 474.7 μM, respectively.     

Esterase-16 (ES-16) of the rat (Rattus norvegicus): Identification and genetic characterization

Esterase-16, an esterase present in lung and other tissues of the laboratory rat, has been characterized by its biochemical properties (electrophoretic mobility, substrate pattern, sensitivity to inhibitors) and genetic variation in 107 inbred strains and substrains including 14 RI strains. It was classified as a carboxylesterase (EC 3.1.1.1). The phenotype ES-16A (BN/Han and 63 other strains) was defined as a narrow electrophoretic band migrating between ES-1A and ES-13A, ES-16B (LEW/Han and 42 other strains) exhibited the same electrophoretic mobility as ES-16A but was distinguished by its extremely weak activity. Segregation of ES-16 in RI strains and backcrosses indicated linkage to linkage group V (LGV). The Es-16 locus was tentatively placed into esterase cluster 2 and homology with Es-7 of the house mouse is proposed.     

Role of dam and pups in the absence of nursing in CPB-B rats (rattus norvegicus)

In rats of the CPB-B strain, the female shows normal parturition behaviour and normal capacity of milk secretion, but the young - all born alive - die within few days of birth. Here, we report that this postnatal mortality is eliminated when CPB-B neonates are crossfostered to mothers of the Wu:Cpb strain; conversely, Wu:Cpb neonates (which are successfully reared by dams of their own strain) die within few days of birth when crossfostered to newly parturient CPB-B rats. It is suggested that pup mortality in CPB-B rats is due to inadequate maternal care resulting, supposedly, from susceptibility of the mother to disturbing environmental stimuli.     

Identification of glandular (preputial and clitoral) proteins in house rat (Rattus rattus) involved in pheromonal communication

Proteins (18-20 kDa) belonging to lipocalin family have been reported to act as carriers for ligands binding to pheromones in mouse urine, pig saliva, hamster vaginal fluid and human sweat, that are involved in pheromonal communication. As the preputial gland is a major pheromonal source, the present study was aimed to detect the specific protein bands (around 18-20 kDa) in the preputial and clitoral glands of the house rat, R. rattus. The amount of protein was higher in preputial gland of the male than that of female (clitoral) gland. A 20 kDa protein was noted in male and female glands; however, the intensity of the band was much higher in male than in female. In addition, 70, 60, 35 kDa bands, identified in male preputial gland, were absent in females. The presence of higher concentration of glandular proteins in the male preputial gland suggests that male rats may depend more on these glandular proteins for the maintenance of reproductive and dominance behaviours. The results further suggest that these glandular proteins (20 kDa) may act as a carrier for ligand binding.     

The sedative effects of climazolam and climazolam with fentanyl-fluanisone in rats (Rattus norvegicus)

A trial of the sedative effects of a novel benzodiazepine, climazolam, and of a mixture of climazolam and fentanyl-fluanisone was undertaken in male and female Sprague Dawley and Lewis strain rats (Rattus norvegicus) of different ages. At the recommended intravenous therapeutic dosage of 0.25 mg/kg, climazolam sedated the rats but failed to inhibit the righting reflex or responses to painful stimuli. Even at 25 times the recommended dosage, there was no anaesthetic effect. Predictable and satisfactory surgical anaesthesia was not obtained with the mixture of climazolam and fentanyl-fluanisone administered intraperitoneally. In contrast with diazepam and midazolam, climazolam failed to potentiate the sedative analgesic properties of fentanyl-fluanisone: indeed many animals retained their tail and pedal pinch reflexes. The results also revealed significant differences in effect related to strain and age but not to sex.