Molecular characterization of a Cryptosporidium isolate from a black bear

To further validate the observation of the existence of host-adapted strains of Cryptosporidium parvum, we genetically characterized an isolate of Cryptosporidium parasite from a black bear. Sequence analysis of the ribosomal RNA small subunit and the 70-kDa heat shock protein (HSP70) showed that this parasite represents a new genotype of C. parvum and is related to the C. parvum dog genotype. This finding is helpful for clarifying Cryptosporidium taxonomy.     

Cryptosporidiosis in a black bear in Virginia

Cryptosporidiosis has not been previously reported in black bears in North America, either free-roaming or captive. However, oocysts have been documented in two captive Malayan sun bears (Helarctos malayanus) located in zoological parks in Taiwan. Developmental stages of Cryptosporidium parvum were observed in tissue sections from the small intestine of a black bear cub found dead in Virginia (USA).     

Trombiculiasis in the Florida black bear

We found trombiculid mite (Trombiculidae) infestations in 32 of 101 (32%) freeranging Florida black bears (Ursus americanus floridanus) live-captured or necropsied in Florida from January 1999 to April 2000. Prevalence of chigger infestation was greatest in June with no infestations seen October to March. Chigger infestations were recognized as accumulations of bright orange granular material usually associated with hair shafts. Mites were found in clusters of one to 102 (mean +/- SD = 8.5+/-19.5) and were distributed primarily over the ventral abdomen and thorax, inguinal and axillary regions, and proximal medial aspect of the extremities. Mites were identified as larval Eutrombicula splendens. Cutaneous lesions were seen in two of 32 (6%) infested bears.     

Pityrosporum pachydermatis in a black bear (Ursus americanus)

Pityrosporum pachydermatis was repeatedly isolated from portions of alopecic tissue from the throax and ears of a black bear cub (Ursus americanus). Yeastlike cells morphologically identical with those of P. pachydermatis were observed in stained tissue sections. This is the first reported association of this yeast with a member of the family Ursidae.     

Glycerol metabolism in the hibernating black bear

Summary The contribution of glycerol to protein, carbohydrate, and lipid metabolism was studied in black bears. Special attention was directed at the role of glycerol in preventing uremia. In summer and winter, U-¹⁴C glycerol, as well asl(U¹⁴C)-alanine andd(U-¹⁴C)-glucose were injected intravenously; timed sampling of venous blood and expiratory gases was made.In winter, during hibernation,¹⁴C-label from glycerol was found in alanine and other free amino acids and plasma proteins, pyruvate, lactate, glucose and lipid esters. After 48 h, most of the¹⁴C-label in plasma was found in proteins. However, during the four days of study, no label was found in serum urea. Similar results occurred in summer except, in marked contrast to winter,¹⁴C-labeled urea was continually detected in blood. Expired¹⁴C-CO₂ was considerably lower in winter than summer and winter respiratory quotient was 0.69.In both summer and winter,¹⁴C-labeled alanine also entered plasma proteins and generated pyruvate, lactate and glucose. Once again the marked difference between active and dormant phases was demonstrated: There was no labeled plasma urea in winter while it was continually detected in summer. ¹⁴C-labeled glucose experiments revealed very slow carbohydrate metabolism in winter.These findings suggest that in winter, glycerol helps prevent uremia by serving as a carbon source for amino acid formation. The nitrogen involved in these reactions is thus diverted from urea synthesis into protein synthetic pathways. Further, glycerol also appears to serve as an active substrate for gluconeogenesis and lipogenesis in hibernation.     

Tetranucleotide microsatellite loci from the black bear (Ursus americanus)

We describe primers and polymerase chain reaction conditions to amplify 21 tetranucleotide microsatellite DNA loci in black bears (Ursus americanus). We tested primers using individuals from two populations, one each in Georgia and Florida. Among individuals from Georgia (n = 29), primer pairs yielded an average of 2.9 alleles (range, one to four) and an average observed heterozygosity (H_O) of 0.50 (range, 0.00 to 0.79). Among individuals from Florida (n = 19), primer pairs yielded an average of 5.7 alleles (range, one to 14) and an H_O of 0.55 (range, 0.00 to 1.00). A comparison of previously developed markers with individuals from Georgia suggests that bear populations in Georgia and Florida have reduced allelic diversity relative to other populations.     

Microsatellite analysis of genetic variation in black bear populations

Measuring levels of genetic variation is an important aspect of conservation genetics The informativeness of such measurements is related to the variability of the genetic markers used; a particular concern in species, such as bears, which are characterized by low levels of genetic variation resulting from low population densities and small effective population sizes We describe the development of microsatellite analysis in bears and its use in assessing interpopulation differences in genetic variation in black bears from three Canadian National Parks These markers are highly variable and allowed identification of dramatic differences in both distribution and amount of variation between populations Low levels of variation were observed in a population from the Island of Newfoundland The significance of interpopulation differences in variability was tested using a likelihood ratio test of estimates of θ= 4 N_eu.     

Prosthetic valvular endocarditis due to the fungus Paecilomyces

The third reported case of prosthetic valvular endocarditis caused by the fungus Paecilomyces is presented. The clinical course of the patient is discussed. The distinctive morphology of the fungus is described, together with the histologic and cytologic features found in the excised prosthetic valve and in the tissues at autopsy. Prosthetic valvular endocarditis presents a serious antibiotic and surgical problem in therapy. Despite antifungal antibiotics and valve replacement this patient died as a result of metastatic cerebral microabscesses and subarachnoid hemorrhage.     

Ten novel tetranucleotide microsatellite DNA markers from Asiatic black bear, Ursus thibetanus

Ten polymorphic microsatellite markers were developed for the endangered Formosan black bear (Ursus thibetanus formosanus) from a partial genomic library enriched for GAAA repeat. Polymorphism of these loci was evaluated in 27 Formosan black bear specimens of unknown relationship. The number of alleles per locus ranged from 5 to 15 and the observed heterozygosity of each locus ranged from 0.556 to 0.889. These loci should provide useful molecular tools to study conservation genetics of the Formosan black bear and other Asiatic black bears.     

Phylogeography and pleistocene evolution in the North American black bear

To determine the extent of phylogeographic structuring in North Americanblack bear (Ursus americanus) populations, we examined mitochondrial DNAsequences (n = 118) and restriction fragment length polymorphism profiles(n = 258) in individuals from 16 localities. Among the bears examined, 19lineages falling into two highly divergent clades were identified. Theclades differ at 5.0% of nucleotide positions, a distance consistent withan origin 1.8 MYA, and have different but overlapping geographicaldistributions. Areas of clade cooccurrence show that eastern and westernpopulations are currently mixing, but regional differences in lineagedistribution suggest that mixing has begun only recently. The long-termpopulation history of black bears appears to be characterized predominantlyby long-term regional isolation followed by recent contact andhybridization. Congruence between the pattern of diversity observed inblack bears and patterns of forest refuge formation during the Pleistocenesupports earlier speculation that Pleistocene forest fragmentationsunderlie a common pattern in the phylogeography of North American foresttaxa.     

Ecto- and endoparasites of the black bear in northern Wisconsin

Parasites collected from free-ranging black bears, Ursus americanus, in northern Wisconsin included Dermacentor variabilis, D. albipictus, Ixodes scapularis, Demodex sp., Trichodectes pinguis euarctidos, Baylisascaris transfuga and Dirofilaria ursi. Mange, possibly caused by the Demodex sp., also was observed. Dental caries were common and periodontal disease was observed in one animal.     

Breeding behavior of the American black bear Ursus americanus

By means of videotape, we observed and timed courtship, mating, and refractoriness in the American black bear while confined in a semicaptive environment. Sixty-six courtships resulted in mating. During courtship, the male detected estrus and receptivity in the female. Courtship lasted 22.5+/-2.3s (mean+/-S.E.M.). We videotaped and reviewed 61 matings that included mounts, pelvic thrusts, and flutters. Mating lasted 51.6+/-4.2s. Within these 61 matings, there were 24 pelvic thrusts and 14 flutters observed. Pelvic thrusts averaged 2.3+/-0.3 times, while flutters averaged 11.1+/-2.9 times. Of the 61 courtship-mating segments, 28 segments depicted a male refractory period, while 27 segments depicted a female refractory period. The male refractory period lasted 44.9+/-6.1s during which the male sat and licked his genital region. The female walked, ran away, or turned and attacked the male during her 54.2+/-8.3s refractory period. This is the first time a large number of paired ursid matings has been described and timed.     

Parasites from the Asiatic black bear (Ursus thibetanus) on Kyushu Island, Japan

Two Dirofilaria ursi, six Trichodectes pinguis and numerous Haemaphysalis megaspinosa were obtained from an Asiatic black bear (Ursus thibetanus) shot in Kyushu, Japan. The presence of two parasites specific to black bears may indicate the existence of a wild population, although the bears are regarded to be extinct on Kyushu Island.     

Renal microvasculature of the black bear (Ursus americanus)

This study of the Black bear (Ursus americanus) was undertaken to provide basic information related to structural modifications in the renal microvasculature that might provide insight into the drastic alteration in renal urinary output that occurs during winter sleep. Vascular casts, as well as light microscopy and scanning electron microscopy, were used to study the vascular components of the juxtaglomerular complex and related vessels. Histologically, arterial cushions were readily identified at the origin of the afferent arterioles. In the area of the juxtaglomerular complex, the wall of the afferent arteriole appeared to be highly modified. The smooth muscle cells at this site demonstrated a change in morphology and orientation, and the diameter of the arteriole was altered. The pattern of the vascular casts at the origin of the afferent arteriole varied from that portion at the glomerulus, suggesting a modification of the vascular wall near the renal corpuscle. Although the morphology of the renal microvasculature of the Black bear is similar to that of other mammals in some aspects, it is dissimilar to that of other carnivores and of the human kidney in that there are structural modifications of the afferent arteriole that may contribute to a reduction of blood flow to the nephron during winter sleep.     

Prevalence of Trichinella spiralis in black bears (Ursus americanus) from Newfoundland and Labrador, Canada.

Tongue and diaphragm samples from 158 black bears (Ursus americanus) from Newfoundland and Labrador were examined for Trichinella spiralis. No larvae were detected in samples from the island of Newfoundland but one animal from the Labrador samples was infected. The results of this and other studies suggest a lack of involvement of the black bear in a sylvatic cycle of T. spiralis in eastern Canada.