Cross-transmission studies with Eimeria arizonensis-like oocysts (Apicomplexa) in New World rodents of the Genera baiomys, Neotoma, Onychomys, Peromyscus, and Reithrodontomys (Muridae).

Cross-transmission experiments were performed using oocysts of an Eimeria arizonensis-like coccidian from Peromyscus leucopus and Peromyscus truei, an E. arizonensis-like coccidian from Reithrodontomys fulvescens, Eimeria baiomysis and Eimeria taylori from Baiomys taylori, Eimeria albigulae from Neotoma albigula, and Eimeria onychomysis from Onychomys spp., between representatives of the above host genera. The E. arizonensis-like coccidian from R. fulvescens infected Reithrodontomys megalotis, Reithrodontomys montanus, and Peromyscus leucopus. Oocysts of E. arizonensis from P. leucopus could be transmitted to both P. leucopus and R. megalotus. Oocysts of E. baiomysis and E. taylori infected only B. taylori. Oocysts of E. arizonensis from P. truei infected P. truei but not Neotoma mexicana or Onychomys leucogaster. Oocysts of E. albigulae from N. albigula were infective for N. mexicana but not for P. truei or O. leucogaster. Oocysts of E. onychomysis from Onychomys spp. infected O. leucogaster but not N. mexicana or P. truei. These results demonstrate that Peromyscus and Reithrodontomys, genera known to be related very closely evolutionarily, are capable of sharing E. arizonensis, whereas morphologically similar coccidians (E. albigulae, E. baiomysis, and E. onychomysis) from more distantly related hosts, are probably distinct and more stenoxenous. This also is the first report of coccidians infecting species of Reithrodontomys.     

New Species of Eimeria from Arizona Rodents

SUMMARY. In a survey of 52 rodents of 25 species from Grand Canyon National Park, Arizona and its vicinity, the following species of Eimeria are described: E. tamiasciuri n. sp. from the red or spruce squirrel, Tamiasciurus hudsonicus; E. lateralis n. sp. and Eimeria sp. from the mantled ground squirrel, Citellus lateralis; E. eutamiae n. sp. from the cliff chipmunk, Eutamias dorsalis; E. thomomysis n. sp. from the pocket gopher, Thomomys bottae; E. perognathi n. sp. from the rock pocket mouse, Perognathus intermedius; E. albigulae n. sp. from the white-throated woodrat, Neotoma albigula; E. operculata n. sp. from Stephens' woodrat, Neotoma stephensi; E. peromysci n. sp. and E. arizonensis n. sp. from the piñon mouse, Peromyscus truei; E. eremici n. sp. from the cactus mouse, Peromyscus eremicus ; and E. onychomysis n. sp. from the northern grasshopper mouse, Onychomys leucogaster.     

Cross-transmission studies with Eimeria arizonensis, E. arizonensis-like oocysts and Eimeria langebarteli: host specificity at the genus and species level within the Muridae

Cross-transmission experiments were done using sporulated oocysts of Eimeria arizonensis from Peromyscus truei and Peromyscus maniculatus, and oocysts of 2 putative species that resemble E. arizonensis, i.e., Eimeria albigulae from Neotoma albigula, and Eimeria onychomysis from Onychomys leucogaster. Oocysts of each species were inoculated into representatives of P. maniculatus and the latter 2 rodent species. Other experiments were conducted wherein oocysts of Eimeria langebarteli from Peromyscus leucopus were given to P. truei and P. maniculatus. Oocysts of E. arizonensis from P. truei and P. maniculatus could be transmitted only to P. maniculatus; likewise, oocysts of E. albigulae and E. onychomysis produced patent infections only in N. albigula and O. leucogaster, respectively. Oocysts of E. langebarteli from P. leucopus could be transmitted to P. truei, but not P. maniculatus. These results indicate that E. arizonensis, and the morphologically similar E. albigulae and E. onychomysis, are distinct species that are not transmissible between the genera of their respective hosts (Peromyscus, Neotoma, Onychomys), and that some isolates of E. langebarteli, reported from 6 species of Peromyscus and Reithrodontomys megalotis, may not always be infective to P. maniculatus.     

Molecular systematics of the genus Neotoma

DNA sequences from the mitochondrial DNA cytochrome-b gene were used to infer the systematic relationships of 13 species of wood rats (genus Neotoma). Parsimony, likelihood, and neighbor-joining analyses produced similar topologies in most cases and produced six systematic conclusions. First, results of previous studies were supported in the recognition of N. floridana magister as distinct species (N. magister). Second, evidence was provided for the recognition of cryptic species within N. albigula (N. albigula and N. leucodon) and N. mexicana (N. mexicana, N. isthmica, and N. picta). Third, the subgenus Neotoma is composed of four species groups (floridana, lepida, mexicana, and micropus). Fourth, support was provided for placement of N. stephensi within the lepida species group. Fifth, support was provided for the recognition of Hodomys as a separate genus, sister to Xenomys. Sixth, support for the elevation of the subgenus Teonoma to generic status is discussed.     

Eimeria species (Apicomplexa: Eimeriidae) infecting Peromyscus rodents in the southwestern United States and northern Mexico with description of a new species

Of 198 deermice (Peromyscus spp) collected from various localities in the southwestern United States and northern Mexico, 106 (54%) had eimerian oocysts in their feces when examined. These included 50 of 106 (47%) Peromyscus truei, 34 of 54 (63%) Peromyscus maniculatus, 4 of 17 (24%) Peromyscus leucopus, and 18 of 21 (86%) Peromyscus eremicus. The following Eimeria were identified from infected mice: Eimeria arizonensis and Eimeria langebarteli from P. truei; E. arizonensis, Eimeria peromysci, and Eimeria delicata from P. maniculatus; E. arizonensis and Eimeria lachrymalis n. sp. from P. eremicus; and E. langebarteli from P. leucopus. Of the 106 Peromyscus found positive for Eimeria, 97 (91.5%) harbored only a single eimerian species at the time of examination. Sporulated oocysts of E. lachrymalis n. sp. were ellipsoid, 27-35 X 17-21 (30.8 +/- 1.7 X 19.1-0.9) micron, possessed a smooth wall and one polar granule, but lacked a micropyle and an oocyst residuum. Sporocysts were teardrop-shaped, 9-13 X 6-10 (10.9 +/- 0.9 X 7.9 +/- 0.5) micron, and had a Stieda body and sporocyst residuum, but no substieda body. Prepatent periods in experimental infections were 3-6 days after inoculation (DAI) for E. arizonensis (hosts: P. eremicus, P. maniculatus, P. truei); 4-5 DAI for E. peromysci (host: P. maniculatus); 6-9 DAI for E. langebarteli (hosts: P. truei, P. leucopus); and 8-10 DAI for E. lachrymalis (host: P. eremicus). Patency in these infections lasted 6-11 days for E. arizonensis, 5-10 days for E. peromysci, 14-40+ days for E. langebarteli, and 19-50+ days for E. lachrymalis. Eimeria lachrymalis appears to produce occult infections in P. eremicus that can be reactivated upon inoculation of the host with E. arizonensis.     

Novel Hepatozoon in vertebrates from the southern United States

Novel Hepatozoon spp. sequences collected from previously unrecognized vertebrate hosts in North America were compared with documented Hepatozoon 18S rRNA sequences in an effort to examine phylogenetic relationships between the different Hepatozoon organisms found cycling in nature. An approximately 500-base pair fragment of 18S rDNA common to Hepatozoon spp. and some other apicomplexans was amplified and sequenced from the tissues or blood of 16 vertebrate host species from the southern United States, including 1 opossum (Didelphis virginiana), 2 bobcats (Lynx rufus), 1 domestic cat (Felis catus), 3 coyotes (Canis latrans), 1 gray fox (Urocyon cinereoargenteus), 4 raccoons (Procyon lotor), 1 pet boa constrictor (Boa constrictor imperator), 1 swamp rabbit (Sylvilagus aquaticus), 1 cottontail rabbit (Sylvilagus floridanus), 4 woodrats (Neotoma fuscipes and Neotoma micropus), 3 white-footed mice (Peromyscus leucopus), 8 cotton rats (Sigmodon hispidus), 1 cotton mouse (Peromyscus gossypinus), 1 eastern grey squirrel (Sciurus carolinensis), and 1 woodchuck (Marmota monax). Phylogenetic analyses and comparison with sequences in the existing database revealed distinct groups of Hepatozoon spp., with clusters formed by sequences obtained from scavengers and carnivores (opossum, raccoons, canids, and felids) and those obtained from rodents. Surprisingly, Hepatozoon spp. sequences from wild rabbits were most closely related to sequences obtained from carnivores (97.2% identical), and the sequence from the boa constrictor was most closely related to the rodent cluster (97.4% identical). These data are consistent with recent work identifying prey-predator transmission cycles in Hepatozoon spp. and suggest this pattern may be more common than previously recognized.     

Phylogenetic relationships among rodent Eimeria species determined by plastid ORF470 and nuclear 18S rDNA sequences

Phylogenetic analyses for 10 rodent Eimeria species from different host genera based on plastid ORF470 and nuclear 18S rDNA sequences were done to infer the evolutionary relationships of these rodent Eimeria species and their correlation to morphology and host specificity. The phylogenies based on both data sets clearly grouped the 10 rodent Eimeria species into two major lineages, which reflect more their morphological differences than host specificity. Species in lineage A have spheroidal to subspheroidal sporulated oocysts, are similar in size (18-29 x 17-23; xbar = 22 x 20 microm), have an oocyst residuum and one-two polar granules; these include Eimeria albigulae (Neotoma), Eimeria arizonensis (Peromyscus, Reithrodontomys), Eimeria onychomysis (Onychomys) and Eimeria reedi (Perognathus). Species in lineage B, including Eimeria falciformis (Mus), Eimeria langebarteli (Reithrodontomys), Eimeria nieschulzi (Rattus), Eimeria papillata (Mus), Eimeria separata (Rattus) and Eimeria sevilletensis (Onychomys) have different shapes (ovoid, ellipsoid, elongated ellipsoid, etc.), differ greatly in size (10-27 x 9-24; xbar = 19 x 16 microm) and all lack an oocyst residuum. Thus, The oocyst residuum was the most determinant feature that differentiated the two lineages. The accession numbers of ORF470 of E. albigulae, E. arizonensis, E. falciformis, E. nieschulzi, E. onychomysis, E. papillata, E. reedi, E. separata, E. sevilletensis, E. langebarteli are AF311630-AF311639 and 18S rDNA of E. langebarteli, E. papillata, E. reedi, E. separata, E. sevilletensis are AF311640-AF311644.     

Phylogenetic position of Eimeria antrozoi, a bat coccidium (Apicomplexa: Eimeriidae) and its relationship to morphologically similar Eimeria spp. from bats and rodents based on nuclear 18S and plastid 23S rDNA sequences.

Partial plastid 23S and nuclear 18S rDNA genes were amplified and sequenced from 2 morphologically similar Eimeria species. E. antrozoi from a bat (Antrozous pallidus) and E. arizonensis from deer mice (Peromyscus spp.), as well as some other Eimeria species from bats and rodents. The phylogenetic trees clearly separated E. antrozoi from E. arizonensis. The phylogenies based on plastid 23S rDNA data and combined data of both plastid and nuclear genes grouped 2 bat Eimeria and 3 morphologically similar Eimeria species from rodents into 2 separate clades with high bootstrap support (100%, 3 rodent Eimeria species; 72-97%, 2 bat Eimeria species), which supports E. antrozoi as a valid species. The rodent Eimeria species did not form a monophyletic group. The 2 bat Eimeria species formed a clade with the 3 morphologically similar rodent Eimeria species (E. arizonensis, E. albigulae, E. onychomysis, all from cricetid rodents) with 100% bootstrap support, whereas 2 other rodent Eimeria species (E. nieschulzi, E. falciformis, from murid rodents) formed a separate clade with 100% bootstrap support. This suggests that the 2 Eimeria species from bats might be derived from rodent Eimeria species and may have arisen as a result of lateral host transfer between rodent and bat hosts.     

Ingestion of juniper foliage reduces metabolic rates in woodrat (Neotoma) herbivores

Ingestion of plant secondary compounds by herbivores is predicted to increase resting or basal metabolic rates. We tested this hypothesis with two species of woodrat herbivores, Neotoma stephensi and Neotoma albigula, consuming diets of juniper (Juniperus monosperma), which is rich in plant secondary compounds. In nature, N. stephensi specializes on juniper, whereas N. albigula consumes a variety of plant species including juniper. We measured resting metabolic rates (RMR) of woodrats on control, 25% juniper and a treatment containing the maximum tolerable dose of juniper (50% juniper for N. albigula and 70% juniper for N. stephensi). Ingestion of a juniper diet resulted in decreased RMR in both species of woodrats. We propose several potential mechanisms for metabolic depression of Neotoma on juniper diets. Our novel results underscore the need for more studies utilizing plant-based diets to determine the general effect of plant secondary compounds on metabolic rates of herbivores.     

Eimeria species (Eucoccidida: Eimeriidae) found in the cotton rat Sigmodon hispidus in Costa Rica]

Cotton rats (Sigmodon hispidus) were collected from Ojo de Agua, Alajuela (N = 74) and Ca?as, Guanacaste (N = 29). Feces had 31 E. sigmodontis, nine E. tuskegeensis, eight E. roperi, three E. webbae and two Eimeria sp. This is the first report of these coccidian parasites for Costa Rica.     

北美CHIHUAHUAN荒漠11种啮齿动物种群密度季节性和周期性的比较研究

本文提出了季节性指标并用时间序列方法分析和比较了北美Chihuahuan荒漠11种啮齿动物种群密度的季节性、趋势和周期性。结果表明,研究期各年间盘尼西拉特斯颊囊鼠(C.p-enicillatus)有最显著的季节性,鹿鼠属(Peromyscus)的两个物种和伏拉瓦斯囊鼠(Pg.flav-us)的季节性最无规律;11个种群中有7个有趋势,除旗尾更格卢鼠(D.spectabilis)的种群密度呈减少趋势外,其余6个种群的密度呈增加的趋势;种群密度的周期,麦利阿姆更格卢鼠(D.merriami)是4年,曼利卡拉特斯鹿鼠(P.maniculatus)是4.5年,盘尼西拉特斯颊囊鼠(C.penicillatus)等3个种群是1年。对11个种群的比较说明,这些种群密度的季节性、趋势和周期性呈现出明显的多样化,且与它们的亲缘关系或种系发生历史无显著关系。11个种群的密度变动的多样化维持了它们在时间方面的共存。     

Effects of consumption of juniper (Juniperus monosperma) on cost of thermoregulation in the woodrats Neotoma albigula and Neotoma stephensi at different acclimation temperatures

A study was done to test whether toxic plants that occur naturally in the diet affect thermoregulation in mammalian herbivores. The woodrats Neotoma albigula and Neotoma stephensi both consume juniper (Juniperus monosperma), a plant with high levels of toxic compounds. Body temperature (Tb), basal metabolic rate (BMR), and the minimum cost of thermogenesis (Cmin) were measured for both species on control and juniper diets following warm (25 degrees C) and cold (18 degrees C) acclimation. In N. albigula, diet had no uniform effect on Tb, BMR, or Cmin, but dietxacclimation-temperature interaction effects on Tb and Cmin were highly significant (P<0.005). For thermoregulation at 15 degrees C, juniper consumption increased the metabolic cost for warm-acclimated N. albigula by 50% but decreased the metabolic cost in cold-acclimated N. albigula by 24%. In N. stephensi, diet significantly affected Tb and Cmin (P<0.05), but there were no significant dietxacclimation-temperature interaction effects. For thermoregulation at 15 degrees C, juniper consumption increased the metabolic cost for warm-acclimated N. stephensi by 33% but had no significant effect on metabolic cost in cold-acclimated N. stephensi.     

Serologic evidence of a Rickettsia akari-like infection among wild-caught rodents in Orange County and humans in Los Angeles County, California.

We detected antibodies reactive with Rickettsia akari, the etiologic agent of rickettsialpox in humans and in 83 of 359 (23%) rodents belonging to several species, collected in Orange County, CA. Reciprocal antibody titers >1:16 to R. akari were detected in native mice and rats (Peromyscus maniculatus, P. eremicus, and Neotoma fuscipes) and in Old World mice and rats (Mus musculus, Rattus rattus, and R. norvegicus), representing the first time that antibodies reactive with this agent have been detected in four of these species and the first report of these antibodies in rodents and humans west of the Mississippi River. We then tested serum samples from individuals who used a free clinic in downtown Los Angeles and found that 25 of 299 (8%) of these individuals had antibody titers >1:64 to R. akari. Serologic evidence suggested that R. akari or a closely related rickettsia is prevalent among several rodent species at these localities and that infection spills over into certain segments of the human population. Isolation or molecular confirmation of the agent is needed to conclusively state that R. akari is the etiologic agent infecting these rodents.     

Coccidia (Apicomplexa) from heteromyid rodents in the southwestern United States, Baja California, and northern Mexico with three new species from Chaetodipus hispidus

Fecal samples from 223 heteromyid rodents of 4 genera and 13 species were collected from California, New Mexico, and Texas and from Baja California Norte and Sonora, Mexico. Of these, 84 (38%) were infected with coccidian oocysts; 72 of 84 (86%) infected animals had only 1 species of coccidian. Eleven species of coccidia were identified including 1 cyclosporan and 10 eimerians; the cyclosporan and 2 of the eimerians are described as new species. Sporulated oocysts of Cyclospora angimurinensis n. sp. were subspheroidal, 21.9 x 19.3 (19-24 x 16-22) microns, with sporocysts lemon-shaped, 11.9 x 9.5 (9-15 x 8-11) microns; it was found in 1 of 20 (4%) Chaetodipus hispidus. Sporulated oocysts of Eimeria chaetodipi n. sp. were subspheroidal, 16.7 x 14.6 (13-19.5 x 12-17) microns, with sporocysts ovoidal, 8.7 x 6.6 (7.5-10.5 x 5-7.5) microns; it was found in 3 of 20 (15%) C. hispidus. Sporulated oocysts of Eimeria hispidensis n. sp. were subspheroidal, 20.5 x 17.4 (17-23 x 14-21) microns, with sporocysts lemon-shaped, 9.3 x 7.2 (7.5-10.5 x 5-9) microns; it was found in 4 of 20 (20%) C. hispidus.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ribosomal DNA variation within and between species of rodents, with emphasis on the genus Onychomys

Patterns of restriction-endonuclease site and length variation at the nuclear rDNA locus (18S + 28S rRNA gene complex) were examined in rodents. Of the 164 restriction sites mapped for seven species, 22 were conserved (mapping to the 18S, 28S, and 5.8S genes and ITS1) in all three Onychomys species as well as in Mus musculus and in three closely related peromyscine rodents, Peromyscus boylii, P. eremicus, and Reithrodontomys megalotis. The nontranscribed spacer (NTS) region revealed most of the variation among these taxa, with the patterns of variation grouping into the following categories, (1) intraindividual variation revealing as many as four site-specific repeat types within an individual, (2) intraspecific and interspecific site variation confined to the NTS, and (3) length variation in both the transcribed and NTS regions. Length variation in the 28S rRNA gene was also examined in 17 additional rodent species, and most size differences mapped to the divergent domain, D8, found in sequence comparisons between Mus and Rattus. The systematic implications of rDNA variation are discussed using the perspective gained from these rodent comparisons.     

Pneumocystosis in wild small mammals from California

Cyst forms of the opportunistic fungal parasite Pneumocystis carinii were found in the lungs of 34% of the desert shrew, Notiosorex crawfordi (n = 59), 13% of the ornate shrew, Sorex ornatus (n = 55), 6% of the dusky-footed wood rat, Neotoma fuscipes (n = 16), 2.5% of the California meadow vole, Microtus californicus (n = 40), and 50% of the California pocket mouse, Chaetodipus californicus (n = 2) caught from southern California between February 1998 and February 2000. Cysts were not found in any of the harvest mouse, Reithrodontomys megalotis (n = 21), California mouse, Peromyscus californicus (n = 20), brush mouse, Peromyscus boylii (n = 7) or deer mouse, Peromyscus maniculatus (n = 4) examined. All infections were mild; extrapulmonary infections were not observed. Other lung parasites detected were Hepatozoon sp./spp. from M. californicus and Notiosorex crawfordi, Chrysosporium sp. (Emmonsia) from M. californicus, and a nematode from S. ornatus.     

Eimeria ladronensis n. sp. and E. albigulae (Apicomplexa: Eimeriidae) from the woodrat, Neotoma albigula (Rodentia: Cricetidae)

Of 50 white-throated woodrats (Neotoma albigula) collected from Socorro Co., New Mexico, 21 (42%) had eimerian oocysts in their feces when examined. Of the 21 Neotoma found positive for Eimeria, 19 (90%) harbored a single eimerian species at time of examination. Eimeria albigulae Levine, Ivens & Kruidenier, 1957, was found in 18 (86%), and E. ladronensis n. sp. was found in five (24%) infected woodrats. Sporulated oocysts of E. ladronensis are ellipsoidal, 19-25 X 13-15 (21.4 +/- 1.3 X 14.1 +/- 1.1) micron, have a smooth wall and one or two polar granules, but lack a micropyle and an oocyst residuum. Sporocysts are tapered at one end, 7-10 X 6-7 (8.5 +/- 0.7 X 6.5 +/- 0.3) micron, and have a Stieda body and sporocyst residuum, but no substieda body. Prepatent periods for E. albigulae and E. ladronensis n. sp. are 5-6 and 8-9 days, respectively; patent periods are 7-18 and approximately 11 days, respectively.     

Mammal and flea relationships in the Great Basin Desert: from H. J. Egoscue's collections

Host-parasite association among 58 flea species parasitizing 40 mammal species in the Great Basin Desert of the western United States was investigated. Increased flea species richness was correlated with larger geographic ranges and stable locomotion of hosts. Hosts from habitats of moderately low productivity (sage and grass) and of Peromyscus maniculatus size, 10-33 g, had the highest flea species richness. Larger hosts had fewer flea species, but fleas were more prevalent. Increased host species richness correlated with flea species eye size. Mammals clustered into 3 major and 1 minor ecological groups, and fleas clustered into 2 major groups among rodents, and 6 minor groups, forming 12 host-parasite biocenoses. Factors producing biocenoses were shared burrows of mice and rats; food chains of hares, rabbits, squirrels, and their predators; keystone mammals: Lagurus curtatus, Neotoma lepida, Ochotona princeps, and Spermophilus townsendii; keystone fleas: Megabothris abantis, and Meringis hubbardi; or host isolation, Neotoma cinerea with Oropsylla montana, Sorex vagrans with Corrodopsylla curvata, and Tadarida brasiliensis with Sternopsylla distincta. Although host relatedness accounted for flea prevalence, host sociality explained the presence or absence of mammal-flea relationships.     

Primary immune responses of selected small mammal species to heterologous erythrocytes.

1. We surveyed the primary humoral immune responsiveness of six small mammal species (Peromyscus leucopus, Microtus pinetorum, Perognathus hispidus, Neotoma floridana, Onychomys leucogaster, Mus musculus) collected from wild populations in central Oklahoma using sheep red blood cells (SRBC) as the immunogen and a splenic plaque-forming cell (PFC) assay. 2. Individuals within each wild species examined produced antibodies to a single intraperitoneal injection of SRBC, however, considerable interspecific and intraspecific variation in responsiveness was indicated. 3. Overall, primary immune responsiveness varied from 0 to 5013 PFC/10(6) cells. Spleen weights, total splenic nucleated cell yields, PFC/spleen, PFC/mg spleen, and PFC/10(6) cells were significantly different among species. 4. Mean cell yield in M. pinetorum was greater than in P. leucopus and CD-1 laboratory mice (included as positive controls). Number of PFC/10(6) cells was greater in CD-1 laboratory mice than P. hispidus and P. leucopus. The coefficient of variation for PFC/10(6) cells in CD-1 laboratory mice was 38% compared to 109, 129, and 56% for M. pinetorum, P. hispidus, and P. leucopus, respectively. 5. Interspecific and intraspecific differences among wild species may be a reflection of disparate life histories and other environmental selection pressures.     

Temporal and spatial distribution of Leishmania mexicana infections in a population of Neotoma micropus

A 19-month mark-release-recapture study of Neotoma micropus with sequential screening for Leishmania mexicana was conducted in Bexar County, Texas, USA. The overall prevalence rate was 14.7% and the seasonal prevalence rates ranged from 3.8 to 26.7%. Nine incident cases were detected, giving an incidence rate of 15.5/100 rats/year. Follow-up of 101 individuals captured two or more times ranged from 14 to 462 days. Persistence of L. mexicana infections averaged 190 days and ranged from 104 to 379 days. Data on dispersal, density, dispersion, and weight are presented, and the role of N. micropus as a reservoir host for L. mexicana is discussed.