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.     

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.     

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.     

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.     

Chemical structures of oligosaccharides in milks of the American black bear (Ursus americanus americanus) and cheetah (Acinonyx jubatus)

The milk oligosaccharides were studied for two species of the Carnivora: the American black bear (Ursus americanus, family Ursidae, Caniformia), and the cheetah, (Acinonyx jubatus, family Felidae, Feliformia). Lactose was the most dominant saccharide in cheetah milk, while this was a minor saccharide and milk oligosaccharides predominated over lactose in American black bear milk. The structures of 8 neutral saccharides from American black bear milk were found to be Gal(β1–4)Glc (lactose), Fuc(α1–2)Gal(β1–4)Glc (2′-fucosyllactose), Gal(α1–3)Gal(β1–4)Glc (isoglobotriose), Gal(α1–3)[Fuc(α1–2)]Gal(β1–4)Glc (B-tetrasaccharide), Gal(α1–3)[Fuc(α1–2)]Gal(β1–4)[Fuc(α1–3)]Glc (B-pentasaccharide), Fuc(α1–2)Gal(β1–4)[Fuc(α1–3)]GlcNAc(β1–3)Gal(β1–4)Glc (difucosyl lacto-N-neotetraose), Gal(α1–3)Gal(β1–4)[Fuc(α1–3)]GlcNAc(β1–3)Gal(β1–4)Glc (monogalactosyl monofucosyl lacto-N-neotetraose) and Gal(α1–3)Gal(β1–4)GlcNAc(β1–3)Gal(β1–4)Glc (Galili pentasaccharide). Structures of 5 acidic saccharides were also identified in black bear milk: Neu5Ac(α2–3)Gal(β1–4)Glc (3′-sialyllactose), Neu5Ac(α2–6)Gal(β1–4)GlcNAc(β1–3)[Fuc(α1–2)Gal(β1–4)GlcNAc(β1–6)]Gal(β1–4)Glc (monosialyl monofucosyl lacto-N-neohexaose), Neu5Ac(α2–6)Gal(β1–4)GlcNAc(β1–3)[Gal(α1–3)Gal(β1–4)GlcNAc(β1–6)]Gal(β1–4)Glc (monosialyl monogalactosyl lacto-N-neohexaose), Neu5Ac(α2–6)Gal(β1–4)GlcNAc(β1–3){Gal(α1–3)Gal(β1–4)[Fuc(α1–3)]GlcNAc(β1–6)}Gal(β1–4)Glc (monosialyl monogalactosyl monofucosyl lacto-N-neohexaose), and Neu5Ac(α2–6)Gal(β1–4)GlcNAc(β1–3){Gal(α1–3)[Fuc(α1–2)]Gal(β1–4)[Fuc(α1–3)]GlcNAc(β1–6)}Gal(β1–4)Glc (monosialyl monogalactosyl difucosyl lacto-N-neohexaose). A notable feature of some of these milk oligosaccharides is the presence of B-antigen (Gal(α1–3)[Fuc(α1–2)]Gal), α-Gal epitope (Gal(α1–3)Gal(β1–4)Glc(NAc)) and Lewis x (Gal(β1–4)[Fuc(α1–3)]GlcNAc) structures within oligosaccharides. By comparison to American black bear milk, cheetah milk had a much smaller array of oligosaccharides. Two cheetah milks contained Gal(α1–3)Gal(β1–4)Glc (isoglobotriose), while another cheetah milk did not, but contained Gal(β1–6)Gal(β1–4)Glc (6′-galactosyllactose) and Gal(β1–3)Gal(β1–4)Glc (3′-galactosyllactose). Two cheetah milks contained Gal(β1–4)GlcNAc(β1–3)[Gal(β1–4)GlcNAc(β1–6)]Gal(β1–4)Glc (lacto-N-neohexaose), and one cheetah milk contained Gal(β1–4)Glc-3’-O-sulfate. Neu5Ac(α2–8)Neu5Ac(α2–3)Gal(β1–4)Glc (disialyllactose) was the only sialyl oligosaccharide identified in cheetah milk. The heterogeneity of milk oligosaccharides was found between both species with respect of the presence/absence of B-antigen and Lewis x. The variety of milk oligosaccharides was much greater in the American black bear than in the cheetah. The ratio of milk oligosaccharides-to-lactose was lower in cheetah (1:1–1:2) than American black bear (21:1) which is likely a reflection of the requirement for a dietary supply of N-acetyl neuraminic acid (sialic acid), in altricial ursids compared to more precocial felids, given the role of these oligosaccharides in the synthesis of brain gangliosides and the polysialic chains on neural cell adhesion.

     

A new species of Sarcocystis (Apicomplexa: Sarcocystidae) from the black bear (Ursus americanus)

Infection with Sarcocystis species is common in herbivores but is rare in bears. Histological sections of 374 black bears (Ursus americanus) from Pennsylvania were examined for sarcocysts. In total, 3 sarcocysts were found in 3 bears, with 1 sarcocyst per section. Sarcocysts from 2 bears were considered a new species, Sarcocystis ursusi. Sarcocysts of S. ursusi n. sp. were microscopic and contained only bradyzoites. By light microscopy, the sarcocyst wall was thin (< 0.5 microm thick) and had minute serrations. Ultrastructurally, the serrations on the sarcocyst wall consisted of villar protrusions (Vp) that were mostly 0.5 microm long. The Vp had bundles of electron-dense microtubules that were as wide as long; these microtubules extended deep into the ground substance layer, a feature that distinguished this species from unnamed sarcocysts from black bear. Bradyzoites were 4.8-6.0 microm long. The sarcocyst from the third bear was structurally different from S. ursusi; its sarcocyst wall was approximately 2 microm thick and had finger-like villi on the cyst wall giving the sarcocyst wall a striated appearance.     

Anaerobic oral flora in the North American black bear (Ursus americanus) in eastern North Carolina

Microbial flora can provide insight into the ecology and natural history of wildlife in addition to improving understanding of health risks. This study examines the anaerobic oral flora of hunter killed black bears (Ursus americanus) in eastern North Carolina. Oral swabs from the buccal and lingual supragingival tooth surfaces of the first and second mandibular and maxillary molars of 22 black bears were inoculated onto Brucella Blood Agar plates supplemented with hemin and vitamin K after transport from the field using reduced oxoid nutrient broth. Sixteen anaerobic bacterial species, representing nine genera were identified using the RapID ANA II Micromethod Kit system and a number of organisms grown that could not be identified with the system. The most frequently identified anaerobes were Peptostreptococcus prevotii, Streptococcus constellatus, and Porphyromonas gingivalis. The diversity in the anaerobic oral flora of black bear in eastern North Carolina suggests the importance of including these organisms in basic health risk assessment protocols and suggests a potential tool for assessment of bear/habitat interactions.     

Seasonal regulation of the growth hormone-insulin-like growth factor-I axis in the American black bear (Ursus americanus)

The American black bear maintains lean body mass for months without food during winter denning. We asked whether changes in the growth hormone/insulin-like growth factor-I (GH-IGF-I) axis may contribute to this remarkable adaptation to starvation. Serum IGF-I levels were measured by radioimmunoassay, and IGF-binding proteins (IGFBPs) were analyzed by ligand blotting. Initial studies in bears living in the wild showed that IGF-I levels are highest in summer and lowest in early winter denning. Detailed studies in captive bears showed that IGF-I levels decline in autumn when bears are hyperphagic, continue to decline in early denning, and later rise above predenning levels despite continued starvation in the den. IGFBP-2 increased and IGFBP-3 decreased in early denning, and these changes were also reversed in later denning. Treatment with GH (0.1 mg·kg(-1)·day(-1) × 6 days) during early denning increased serum levels of IGF-I and IGFBP-3 and lowered levels of IGFBP-2, indicating that denning bears remain responsive to GH. GH treatment lowered blood urea nitrogen levels, reflecting effects on protein metabolism. GH also accelerated weight loss and markedly increased serum levels of free fatty acids and β-hydroxybutyrate, resulting in a ketoacidosis (bicarbonate decreased to 15 meq/l), which was reversed when GH was withdrawn. These results demonstrate seasonal regulation of GH/IGF-I axis activity in black bears. Diminished GH activity may promote fat storage in autumn in preparation for denning and prevent excessive mobilization and premature exhaustion of fat stores in early denning, whereas restoration of GH/IGF activity in later denning may prepare the bear for normal activity outside the den.     

Negative density-dependent dispersal in the American black bear (Ursus americanus) revealed by noninvasive sampling and genotyping

Although the dispersal of animals is influenced by a variety of factors, few studies have used a condition-dependent approach to assess it. The mechanisms underlying dispersal are thus poorly known in many species, especially in large mammals. We used 10 microsatellite loci to examine population density effects on sex-specific dispersal behavior in the American black bear, Ursus americanus. We tested whether dispersal increases with population density in both sexes. Fine-scale genetic structure was investigated in each of four sampling areas using Mantel tests and spatial autocorrelation analyses. Our results revealed male-biased dispersal pattern in low-density areas. As population density increased, females appeared to exhibit philopatry at smaller scales. Fine-scale genetic structure for males at higher densities may indicate reduced dispersal distances and delayed dispersal by subadults.     

Membrane transport of sodium ions in erythrocytes of the American black bear, Ursus americanus

1. Membrane transport of Na ions was investigated in red blood cells of bears by methods of measurement of unidirectional isotopic fluxes. 2. Like red blood cells of dogs, bear red cells contain a high Na concentration and low concentrations of K and ATP. 3. As in dog red cells, Na efflux from bear cells was not inhibited by ouabain but was activated by the presence of Ca in the medium, possibly indicating the presence of a Na-Ca exchange mechanism. 4. ATP depletion of cells was accelerated by Ca in the medium, consistent with the presence of a strong ATP-dependent Ca pump. 5. As in other carnivore red cells, Na influx into bear cells was strongly activated by shrinkage and inhibited by swelling. Shrinkage-activated influx was blocked by amiloride. 6. Amiloride-sensitive influx was activated by cytoplasmic Ca and also correlated with the presence of a Na-dependent, amiloride-sensitive H loss. 7. Amiloride-sensitive Na influx exhibited a strong seasonal cycle with a minimum in the middle of the hibernation period, suggesting a possible avenue of cellular energy conservation.     

Membrane transport of potassium ions in erythrocytes of the American black bear, Ursus americanus

1. Membrane transport of K ions was investigated in red blood cells of bears by methods of measurement of unidirectional isotopic fluxes. 2. Unlike red cells of dogs, red cells of bears exhibited a significant, though small, component of ouabain-sensitive K influx. 3. Ouabain-insensitive K influx, as in other carnivore cells, was activated by swelling and inhibited by shrinkage. Swelling-induced K influx was dependent upon presence of chloride ions but was not inhibited by furosemide or bumetanide. 4. Ouabain-sensitive K influx was largest with ATP and with high concentration of Na in the cell, but it persisted in the absence of cytoplasmic Na or ATP. It was also resistant to the drug, harmaline, at a concentration that in other cells fully inhibits ouabain-sensitive K influx. 5. It was concluded that under such adverse conditions ouabain-sensitive K influx represents another mode of the Na/K pump not fully described elsewhere. 6. Also, as in low K red cells of sheep and goat, apparent absence of Na/K pump activity in carnivore red cells may represent suppression rather than elimination of activity. 7. Ouabain-insensitive K influx showed a seasonal pattern with minima occurring in early winter, earlier than for the minimum observed in Na influx. 8. Ouabain-sensitive K influx tended to be lower in the hibernation season of the bear, but the seasonal pattern was not consistent.     

Trichinella spiralis in the black bear (Ursus americanus) of Pennsylvania: distribution, prevalence and intensity of infection

Samples of tongue or diaphragm from 2,056 black bears harvested in Pennsylvania during the 1981-1983 hunting seasons were examined for larvae of Trichinella spiralis by peptic digestion. Sixteen males and 21 females were infected. The overall prevalence of infection was 1.8%. Infected animals were distributed widely throughout the range of the bear in Pennsylvania. In samples from infected bears, the geometric mean density of muscle larvae was 7.8 per g of tissue (LPG). There were neither sex- nor age-related differences in prevalence or intensity of infection. Virtually all bears harvested in Pennsylvania are consumed as food, which often is shared widely among hunters, their friends and relatives. Furthermore, high densities of larvae occurred in some bears (i.e., 300, 348, 465, 512, 555, and 912 LPG). Thus, a basis for potential, single-source outbreaks of severe human trichinosis exists.     

Arterial supply and venous drainage of the brain of the black bear (Ursus americanus). II. Intracranial microvasculature

A morphological study of the intracranial microvasculature of the Black bear (Ursus americanus) using vascular casts was undertaken. The object was to provide basic information regarding structural modifications of the microvasculature that might provide insight into the ability to cope with low blood flow states that occur during winter sleep. Vascular casts were prepared from 6 animals. The microvasculature of the brain disclosed characteristic features of the small vessels in mammals, including vascular sphincters of two types and numerous arterial and arteriolar anastomoses.     

Characterization of 29 tetranucleotide microsatellite loci in black bear (Ursus americanus) for use in forensic and population applications

We developed 29 forensic quality tetranucleotide microsatellite loci for the identification of individual black bear (Ursus americanus). Allele number averaged 5.35 and ranged from 3 to 11. The eight markers selected for forensic use permit the identification and exclusion of individual bear with a probability of identity of approximately 8.1 × 10⁻⁸ (approximately one per 12 million).     

Studies of endoparasites of the mourning dove (Zenaida macroura) in the southeast United States.

From September, 1973, through November, 1974, 255 mourning doves (Zenaida macroura) were collected in the southeastern United States and examined for endoparasites. Thirteen species of endoparasites were found and included six species of protozoans, one trematode, two cestodes, and four nematodes. New host records included Sarcocystis sp., Echinostoma revolutum, Hymenolepis sp., Aproctella stoddardi, Ascaridia columbae, and Dispharynx nasuta.     

Prevalence of sarcocysts in Florida black bears (Ursus americanus floridanus)

Sections of muscle from Florida black bears (Ursus americanus floridanus) collected in the state of Florida were observed for the presence of Sarcocystis sp. sarcocysts. Two of 132 (1.5%) black bears had muscle sections containing sarcocysts. One sarcocyst was observed per muscle section. The sarcocysts averaged 181.5 x 99.0 microm by light microscopy of hematoxylin and eosin-stained sections.     

Arterial supply and venous drainage of the brain of the black bear (Ursus americanus). I. Gross anatomical distribution

A morphological study of the intracranial vessels of the Black bear (Ursus americanus) was undertaken. The object was to provide basic information related to the vascular pattern in these animals as compared with other carnivores and with the human. Vascular casts were prepared from 6 animals. The vasculature of the brain disclosed patterns comparable to other species previously studied.