Roles of insulin resistance and beta-cell dysfunction in dexamethasone-induced diabetes.

The roles of insulin resistance and beta-cell dysfunction in glucocorticoid-induced diabetes were determined in Wistar and Zucker (fa/fa) rats. All Wistar rats treated with 5 mg/kg per d of dexamethasone for 24 d exhibited increased beta-cell mass and basal and arginine-stimulated insulin secretion, indicating insulin resistance, but only 16% became diabetic. The insulin response to 20 mM glucose was normal in the perfused pancreas of all normoglycemic dexamethasone-treated rats but absent in every diabetic rat. Immunostainable high Km beta-cell transporter, GLUT-2, was present in approximately 100% of beta-cells of normoglycemic rats, but in only 25% of beta cells of diabetic rats. GLUT-2 mRNA was not reduced. All Zucker (fa/fa) rats treated with 0.2-0.4 mg/kg per d of dexamethasone for 24 d became diabetic and glucose-stimulated insulin secretion was absent in all. High Km glucose transport in islets was 50% below nondiabetic controls. Only 25% of beta cells of diabetic rats were GLUT-2-positive compared with approximately 100% in controls. Total pancreatic GLUT-2 mRNA was increased twofold suggesting a posttranscriptional abnormality. We conclude that dexamethasone induces insulin resistance, whether or not it induces hyperglycemia. Whenever hyperglycemia is present, GLUT-2-positive beta cells are reduced, high Km glucose transport into beta cells is attenuated and the insulin response to glucose is absent.

Coccidian Parasites (Apicomplexa: Eimeriidae) of Arkansas Herpetofauna: A Summary with Two New State Records.

Coccidian parasites (Protista: Apicomplexa: Eimeriidae) commonly infect reptiles, and to a lesser degree, amphibians. The family Eimeriidae includes at least 18 genera and 3 of them, Caryospora, Eimeria, and Isospora have been reported previously from various Arkansas herpetofauna. Over the past 3 decades, our community collaborative effort has provided a great deal of information on these parasites found in amphibians and reptiles of Arkansas. Here, we provide a summary of all coccidians reported from herptiles of the state as well as provide 2 new state records for coccidians from non-native Mediterranean geckos, Hemidactylus turcicus.

Coccidia (Apicomplexa: Eimeriidae) of Three-toed Box Turtles, Terrapene carolina triunguis (Reptilia: Testudines), from Arkansas and Oklahoma.

We collected 50 three-toed box turtles (Terrapene carolina triunguis) from 9 counties of Arkansas and 4 counties of Oklahoma, and examined their feces for coccidial parasites. Nine of 24 (38%) turtles from Arkansas and 8 of 26 (31%) from Oklahoma were found to be passing oocysts of Eimeria ornata. This represents two new geographic distributional records for this coccidian. Measurements of individual isolates of E. ornata as well as morphological characteristics are provided with comparison to its original description and to another Terrapene coccidian, Eimeria carri. In addition, we noted an adelid pseudoparasite being passed by a single T. c. triunguis from Oklahoma that likely represents a parasite of arthropods.

Eimeria cryptotis n. sp. (Apicomplexa: Eimeriidae) from the least shrew, Cryptotis parva (Insectivora: Soricidae), in north-central Texas.

From March through November 1987, 14 least shrews, Cryptotis parva (Say), were collected in portions of north-central Texas and examined for coccidian parasites; only 1 (7.1%) was found to be passing oocysts. Eimeria cryptotis n. sp. is described herein as new and represents the only coccidian reported thus far from C. parva. Sporulated oocysts are subspherical, 16.4 x 15.3 (14-18 x 13-17) microns; shape index 1.1 (1.0-1.2) microns. A micropyle and oocyst residuum are absent, but a polar granule is present. The sporocysts are ovoid, 10.6 x 7.0 (9-11 x 6-8) microns; shape index 1.5 (1.4-1.8) microns. Stieda and substieda bodies and a sporocyst residuum are present. The sporozoites are elongate and only 2 could be observed well enough to measure (11.2 x 2.4 and 8.8 x 2.4 microns) because they are normally obscured by the sporocyst residuum. Sporozoites lack refractile bodies and contain a centrally located nucleus. The new species can be distinguished from the majority of insectivore coccidia on the basis of oocyst size.

New host records for Myxidium serotinum (Protozoa: Myxosporea) from North American amphibians.

Three hundred twenty-five amphibians (80 salamanders, 245 frogs and toads) from Arkansas and Texas, representing 28 species within 9 families (Ambystomatidae, Plethodontidae, Salamandridae, Sirenidae, Bufonidae, Hylidae, Leptodacytlidae, Microhylidae, Ranidae) were examined for gall bladder myxosporeans. Of these, 32 (10%) were found to harbor Myxidium serotinum Kudo and Sprague, 1940, including 3 (4%) of the salamanders and 29 (12%) of the frogs and toads. This report documents 6 new host records for M. serotinum in Ambystoma opacum, Bufo americanus charlesmithi, Bufo speciosus, Acris crepitans blanchardi, Gastrophryne olivacea, and Pseudacris streckeri illinoensis. In addition, the Great Plains narrowmouth toad G. olivacea represents the first microhylid host of Myxidium spp. worldwide.

Eimeria lancasterensis (Apicomplexa: Eimeriidae) from the eastern fox squirrel, Sciurus niger (Rodentia: Sciuridae), in north-central Texas.

Eimeria lancasterensis Joseph, 1969, is reported for the first time from the feces of 10 of 11 (91%) eastern fox squirrels, Sciurus niger ludovicianus, in Dallas and Johnson counties, Texas. Oocyst measurements were similar to those reported previously from the eastern gray squirrel, Sciurus carolinensis carolinensis, in Massachusetts. Except for our observation of a substieda body, oocyst morphology was identical to the original description of E. lancasterensis.

Description of the oocysts of Eimeria paludosa (Apicomplexa: Eimeriidae) from Fulica americana (Aves: Gruiformes), with comments on synonyms of eimerian species from related birds.

Between November and December 1988, fecal and intestinal contents were collected from 25 northern American coots, Fulica americana americana, in Arkansas and Texas, and examined for coccidial parasites. Seventeen (68%) of the coots were infected with Eimeria paludosa, herein described; for the first time, photomicrographs of the species are presented. Sporulated oocysts are ovoid, 16.5 x 12.6 (15-23 x 11-14) microns, with a lightly to heavily pitted single-layered wall; an oocyst residuum is absent, but a prominent micropyle is present. A large, or several smaller, polar granule(s) is present, usually located beneath the micropyle. Sporocysts are elongate-ovoid, 10.8 x 6.2 (10-12 x 5-7) microns, with Stieda and substieda bodies. A sporocyst residuum is present, normally composed of very fine faint granules scattered among the sporozoites or, rarely, as a spherical mass. Sporozoites are elongate, 8.7 x 2.7 (7-11 x 2-3) microns, in situ. Each sporozoite contains a spherical-ellipsoid posterior refractile body and occasionally a spherical anterior refractile body. A nucleus is located immediately anterior to the posterior refractile body. The occurrence of E. paludosa in F. a. americana is a new host and geographic record for the parasite. In addition, several of the previously described eimerian species from gruiform birds are proposed to be synonyms of E. paludosa.

A new species of coccidian (Apicomplexa: Eimeriidae) from the prairie racerunner, Cnemidophorus sexlineatus viridis (Sauria: Teiidae), in Arkansas.

Feces from 26 prairie racerunners, Cnemidophorus sexlineatus viridis Lowe, 1966, from Arkansas, were examined for coccidian parasites. One of these was found to be infected with oocysts of an undescribed eimerian, which is described herein as new. Sporulated oocysts of Eimeria sexlineatus n. sp. were cylindrical, 30.4 x 17.1 (28-32 x 16-19) microns, with a shape index (length/width) of 1.8 (1.6-2.0). A micropyle and oocyst residuum were absent but 1 (to several) polar granule(s) was present. Sporocysts were ellipsoidal, 10.7 x 8.5 (9.6-11.2 x 8.0-8.8) microns, with a shape index of 1.3 (1.2-1.4). A sporocyst residuum was present but Stieda, substieda, and parastieda bodies were absent. Sporozoites were elongate, 13.2 x 2.7 microns (12.0-14.4 x 2.4-3.2) in situ, containing a single, spherical posterior refractile body. Oocysts and endogenous developmental stages were found within the gall bladder epithelium of the infected lizard. This represents the first time a coccidian has been reported from a North American whiptail lizard.

Coccidian parasites (Apicomplexa: Eimeriidae) of Graptemys caglei and Graptemys versa (Testudines: Emydidae) from Texas.

Nineteen map turtles, Graptemys caglei and Graptemys versa were collected from the Guadalupe and Colorado River watersheds of south-central Texas and examined for coccidial parasites. Thirteen of the 19 turtles (68%), including 11 of 16 (69%) G. caglei and 2 of 3 (67%) G. versa, were infected with at least 1 coccidian. Five Eimeria spp. (E. chrysemydis, E. graptemydos, E. lutotestudinis, E. pseudogeographica, and E. trachemydis) were harbored by G. caglei, and 2 eimerians (E. graptemydos and E. mitraria) infected G. versa. This represents new host records for these previously described coccidians and is the first time parasites have been documented in turtles of both species.

Coccidia (Apicomplexa: Eimeriidae) from the big bend slider, Trachemys gaigeae (Testudines: Emydidae), in New Mexico.

Twenty-nine Big Bend sliders Trachemys gaigeae (Hartweg, 1934) were collected from Socorro County, New Mexico, and their feces examined for coccidial parasites. Three (10%) of the turtles were found to be infected with at least 1 coccidian. Seven Eimeria spp. (E. chrysemydis, E. graptemydos, E. marginata, E. pseudemydis, E. pseudogeographica, E. stylosa, and E. trachemydis) were harbored by T. gaigeae. All represent new host and distributional records for these previously described coccidians. In addition, a single sympatric western painted turtle (Chrysemys picta bellii) harbored E. chrysemydis, E. graptemydos, and E. trachemydis. The latter coccidian is reported for the first time from C. picta bellii.

New host and geographic records for coccidia (Apicomplexa: Eimeriidae) from North American turtles.

Two-hundred-fifty-three turtles, representing 26 species within 5 families (Chelydridae, Emydidae, Kinosternidae, Testudinidae, Trionychidae) were examined for coccidia. Of these, 127 (50%) were found to harbor 1 or more of 28 species of eimerians, or isosporan, or both. One-hundred-thirteen (89%) of the infected turtles were aquatic species, whereas only 14 (11%) of the infected turtles were terrestrial species. Two-fold more aquatic turtles were infected with coccidia (113 of 200, 57%) compared to only 26% (14 of 53) of the terrestrial species. This report documents 14 new host and 8 new geographic records for eimerians from turtles in Arkansas and Texas.

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)

Three new species of Eimeria (Apicomplexa: Eimeriidae) from Apalone spinifera pallidus (Testudines: Trionychidae) in Texas, with a redescription of E. amydae.

Three new species of Eimeria are described from pallid spiny softshells, Apalone spinifera pallidus, collected in north-central Texas. Oocysts of Eimeria spinifera n. sp. were found in the feces of 3/9 (33%) turtles and are subspheroid, ellipsoid, or pear-shaped, 16.3 x 14.0 (14-19 x 12-18) microns, with a thin, single-layered wall; shape index 1.2 (1.1-1.3). A micropyle is absent, but an oocyst residuum is present; polar granule present in 16% of the oocysts. Sporocysts are elongate-ovoid, 10.3 x 5.2 (8-12 x 5-6) microns, each with a Stieda body bearing short filaments. Oocysts of Eimeria apalone n. sp. were found in 5/9 (56%) turtles and are ellipsoid, elongate pear-shaped, or subspheroid, 16.8 x 13.2 (12-19 x 10-16) microns, with a thin, single-layered wall; shape index 1.3 (1.0-1.5). A micropyle, oocyst residuum, and polar granule are absent. Sporocysts are elongate-ovoid, 11.3 x 6.2 (9-14 x 5-7) microns, each with a prominent Stieda body. Oocysts of Eimeria pallidus n. sp. were found in 4/9 (44%) A. s. pallidus and are spheroid or subspheroid, 23.4 x 21.6 (18-27 x 17-25) microns, with a thin, single-layered wall; shape index 1.1 (1.0-1.3). A micropyle is absent, but an oocyst residuum is present; polar granule present in 20% of the oocysts. Sporocysts are elongate-ovoid, 14.3 x 6.2 (13-17 x 6-7) microns, each with a Stieda body and short filaments. In addition to the new species, 3 previously described eimerians, including Eimeria amydae Roudabush, 1937, which is redescribed, were also found.

A description of Isospora amphiboluri (Apicomplexa: Eimeriidae) from the inland bearded dragon, Pogona vitticeps (Sauria: Agamidae).

Fecal samples from 50 captive inland bearded dragons, Pogona vitticeps (Ahl, 1926), bred in California, were examined for coccidian parasites. Sixteen (32%) of the lizards were found to be passing oocysts of Isospora amphiboluri Cannon, 1967, previously described from bearded dragons Pogona barbata (Cuvier, 1829) from Australia. Sporulated oocytes were spherical to subspherical, 25.3 x 25.1 (23-26 x 23-26) microns, with a shape index (length/width) of 1.0 (1.0-1.1). A micropyle, oocyst residuum, and polar granule were absent. Sporocyts were ovoidal, 17.0 x 11.4 (16-18 x 11-12) microns, with a shape index of 1.5 (1.4-1.7). A sporocyst residuum, Stieda, and substieda bodies were present, but parastieda bodies were absent. Sporozoites were elongated, 13.9 x 3.5 (12-15 x 3-4) microns in situ, containing spherical anterior and posterior refractile bodies. The occurrence of I. amphiboluri in P. vitticeps is a new host and geographic record for the parasite. Photomicrographs of the oocysts and endogenous life cycle stages of I. amphiboluri are presented for the first time.

New host and locality records of coccidia (Apicomplexa: Eimeriidae) from rodents in the southwestern and western United States.

One hundred forty-seven murid and heteromyid rodents were collected from various sites in the southwestern and western United States (Arizona, Colorado, New Mexico, Texas, and Utah) and Baja California Norte, Mexico, and their feces were examined for coccidial parasites. Of these, 53 (36%) were infected with at least 1 coccidian; 45 of 53 (85%) of the infected rodents harbored only 1 species of coccidian. Infected rodents included: 10 of 22 (45%) Neotoma albigula, 3 of 11 (27%) Neotoma floridana, 2 of 14 (14%) Neotoma lepida, 15 of 29 (52%) Neotoma micropus, 5 of 8 (63%) Peromyscus crinitis, 6 of 6 (100%) Peromyscus difficilis, 1 of 2 (50%) Peromyscus eremicus, 9 of 34 (26%) Sigmodon hispidis, and 2 of 3 (67%) Sigmodon ochrognathus; 4 Neotoma cinerea, 3 Neotoma devia, 3 Neotoma mexicana, 1 Peromyscus maniculatus, 1 Onychomys leucogaster, 1 Onychomys torridus, 3 Chaetodipus fallax, and 2 Chaetodipus penicillatus were negative. Although no new species was found, the following coccidians were identified from infected rodents: Eimeria albigulae from N. albigula, N. floridana, and N. micropus, Eimeria antonellii from N. albigula and N. micropus, Eimeria ladronensis from N. albigula, N. floridana, N. lepida, and N. micropus, Eimeria arizonensis and Eimeria lachrymalis from P. crinitis and P. difficilis, Eimeria lachrymalis from P. eremicus, Eimeria tuskeegensis from S. ochrognathus, and Eimeria roperi, Eimeria sigmodontis, Eimeria tuskeegensis, Eimeria webbae, and an unidentified species of Eimeria from S. hispidis. This report documents 12 new host and several distributional records for Eimeria species from murid rodents in Arizona, Texas, and Utah.

Coccidian parasites (Apicomplexa) from snakes in the southcentral and southwestern United States: new host and geographic records.

Four hundred thirty-five leptotyphlopid, colubrid, elapid, and viperid snakes were collected from various localities in Arkansas, New Mexico, Oklahoma, and Texas, and their feces were examined for coccidian parasites. Of these, 131 (30%) were passing oocysts or sporocysts of at least 1 coccidian; 88 (67%) of the infected snakes had only 1 species of coccidian when they were examined. Aquatic and semiaquatic snakes accounted for 48% of the infections, whereas strictly terrestrial snakes comprised the other 52%. There was more than a 2-fold difference in prevalence among these 2 groups as 63 of 129 (49%) of the aquatic and semiaquatic snakes versus 68 of 306 (22%) of the terrestrial snakes harbored coccidia. Most terrestrial snakes were infected by species of Caryospora and Sarcocystis that are either facultatively or obligatorily heteroxenous. The aquatic and semiaquatic species most often harbored eimerians. Attempts to transmit some of the Sarcocystis spp. experimentally from Crotalus atrox to Mus musculus, Peromyscus leucopus, Peromyscus maniculatus, or Microtus ochrogaster were unsuccessful. This report documents 27 new host and several distributional records for coccidians from snakes in the southcentral and southwestern United States.

A new host and locality record for Mesocestoides sp. tetrathyridia (Cestoidea: Cyclophyllidea), with a summary of the genus from snakes of the world.

A new host and distribution record is reported for tetrathyridia of Mesocestoides sp. One of 5 (20%) Namib tiger snakes, Telescopus beetzi, from South Africa was infected. Numerous tetrathyridia were found encapsulated in mesentery attached to the small intestine. Morphological examination of tetrathyridia revealed absence of buds, multiple scoleces, or any other evidence of asexual proliferation. A summary of the snakes of the world reported as hosts of tetrathyridia of Mesocestoides sp. is presented.

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.

Prevalence and identity of Sarcocystis infections in armadillos (Dasypus novemcinctus).

Little is known about the prevalence or identity of Sarcocystis species infecting armadillos in North America. Sarcocysts were observed in the tongues of 23 (96%) of 24 armadillos collected between 1989 and 1994 from Texas, Oklahoma, Kansas, and Arkansas. The identity of the species present was determined in histological sections of tongue from armadillos. Sarcocystis dasypi was present in 21 (88%) and Sarcocystis diminuta was present in 5 (21%). Mixed infections with S. dasypi and S. diminuta were present in 3 (13%) armadillos. A single sarcocyst with ultrastructural features distinct from S. dasypi and S. diminuta was observed with transmission electron microscopy.

Morphology of the spermatozoa of the iguanian lizards Uta stansburiana and Urosaurus ornatus (Squamata, Phrynosomatidae).

The spermatozoa of Uta stansburiana and Urosaurus ornatus show the following squamate autapomorphies: a single perforatorium extending anteriorly from the apical tip of the paracrystalline subacrosomal cone; the presence of an epinuclear electron lucent region; intermitochondrial dense bodies; and the fibrous sheath extending into the midpiece. The acrosome vesicle is flattened and concentrically zoned apically; basally it overlies a subacrosomal cone which invests the nuclear rostrum. A stopper-like perforatorial base plate, rounded nuclear shoulders and a basal nuclear fossa are present. The proximal centriole contains a density within its centre for approximately one half its length and lies at approximately 80 degrees to the distal centriole. The two central singlets of the axoneme extend into the short distal centriole. A peripheral dense fibre is associated with each of the nine triplets of the distal centriole, and the fibre continues posteriorly with each of the nine doublets of the axoneme. A central fibre is associated with the two central singlets. All fibres are absent or vestigial at the level of the annulus. Mitochondria are short sinuous with a maximum of eight seen in transverse section. Uta and Urosaurus sperm differ from each other in their arrangement of intermitochondrial dense bodies in two ways: 1) longitudinally, Uta has five incomplete 'rings' of dense bodies, whereas Urosaurus has only four such rings; 2) in cross section, each individual 'ring' of Uta may contain up to four irregularly spaced dense bodies, whereas Urosaurus contains a maximum of only two dense bodies. The sperm of Uta and Urosaurus show strong similarities to those of the agamids and polychrotids. No spermatozoal autapomorphies for the Phrynosomatidae were found.