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M Hoefs

Publications and source records attributed to M Hoefs.

7 recordsLinked to original sources
PubMed2001

Lumpy jaw in wild sheep and its evolutionary implications.

The distribution and prevalence of mandibular osteomyelitis, lumpy jaw, and other dental anomalies in wild sheep were investigated and their biological and evolutionary implications were assessed. Our survey was based on 3,363 mandibles of wild sheep and 1,028 from domesticated varieties. Lumpy jaw is widespread in wild sheep of North America, but it is rare or absent in wild sheep from Eurasia. Among the subspecies of Ovis spp. in North American, the thinhorn sheep (Ovis dalli) were the most seriously impacted, with a prevalence in Dall's sheep (O. dalli dalli) of 23.3% and 29.3% in Stone's sheep (O. dalli stonei). Among the bighorns (O. canadensis), the Rocky Mountain subspecies (O. canadensis canadensis) had a higher rate (12.1%) than other subspecies. Lumpy jaw was not documented in the desert sheep of Baja California (O. canadensis cremnobates, O. canadensis weemsii). Based on data from affected thinhorn sheep, it appears there is an inverse relationship between age of a subspecies in a long term evolutionary context and susceptibility to lumpy jaw. In Eurasian wild sheep lumpy jaw is rare or absent with prevalences ranging from 0 to 7.1% among suspecies, and in domesticated breeds the prevalence averaged 5.0%. The impact of lumpy jaw on different age classes or longevity is equivocal, although females are more susceptible than males. Lumpy jaw appears to effect horn development in males.

Animals↗
PubMed1997

Ether lipids of planktonic archaea in the marine water column.

Acyclic and cyclic biphytanes derived from the membrane ether lipids of archaea were found in water column particulate and sedimentary organic matter from several oxic and anoxic marine environments. Compound-specific isotope analyses of the carbon skeletons suggest that planktonic archaea utilize an isotopically heavy carbon source such as algal carbohydrates and proteins or dissolved bicarbonate. Due to their high preservation potential, these lipids provide a fossil record of planktonic archaea and suggest that they have thrived in marine environments for more than 50 million years.

Journal Article↗
PubMed1992

Cranial asymmetry in a Dall sheep ram (Ovis dalli dalli).

The horns of a 13-yr-old Dall sheep ram (Ovis dalli dalli) from the Sheep Mountain herd in Kluane National Park (Yukon, Canada) had unique characteristics. The right horn was 1,127 mm long, while the left horn was only 861 mm long and compressed and distorted at its base. The reduced growth of the left horn was due to chronic epidermitis and osteomyelitis of the cornual process, which began when the ram was 5 yr of age.

Animals↗
PubMed1984

Further studies on horn aberrations in Dall's sheep (Ovis dalli dalli) from Yukon Territory, Canada.

The prevalence of horn aberrations in Dall's sheep from the Kluane Lake area of Yukon Territory observed during July 1982 represented 1% of the total population and 7% of rams 6 yr or older. Ewes were not considered in these percentages because they were too difficult to inspect by aerial survey. When these data were combined with other data collected from 1977 through 1981, the prevalence equalled 2.4% of the total population and slightly exceeded 16% in mature rams (greater than or equal to 6 yr). The anomaly followed necrosis of the terminal region of the horn core and the sequestering of portions of the core within the sheath as the sheath continued to grow. Sheath that was produced after the core was anatomically altered resulted in abnormal growth patterns of the horn. Rams with aberrant horns could not maintain homeostatic temperatures within horn cores when horns were experimentally exposed to -80 C for 30 min. Histologic examination of superficial and cornual vascular systems did not reveal any structural alterations that would restrict blood flow within cores of affected horns. Examination of museum specimens consisting of 130 skulls from rams and 81 from ewes collected from Alaska, USA, Yukon Territory, Canada, and Northwest Territories, Canada, established only one ewe and no rams with the horn aberration. The skull was from a ewe and had both horns affected and was collected from the Joe River Drainage, Yukon Territory in 1912.

Animals↗
PubMed1982

Horn aberrations in Dall's sheep (Ovis dalli) from Yukon Territory, Canada.

Horn aberrations in Dall's sheep from the Kluane Lake area of Yukon Territory were of two basic types. In the more prevalent type, the horn was severed at an annual growth check and the terminal segment of the remaining portion formed a short conical protuberance. The second type had characteristics of the first, but in addition, underwent extreme twisting or torquing during subsequent growth. Sheep with aberrant horns represented 2% of the Kluane Lake population or 14% of harvestable rams (greater than or equal to 6 yr old). Deformed horns, occurring in ewes and rams, were generally observed in animals 6 yr or older. Aberrations followed necrosis of the terminal segment of the horn core: cavitation of the sheath between successive periods of growth or the sequestering of portions of necrotic core within the sheath resulted. All sheep examined (eight) had a normal complement of 54 chromosomes.

Animal Population Groups↗
PubMed1982

Aberrations of the tooth arcade and mandible in Dall's sheep from southwestern Yukon.

Nine Dall's sheep (Ovis dalli dalli) collected in the Ruby Mountains of southwestern Yukon were examined for aberrations of the tooth arcade and mandible. Missing and displaced teeth were common in older sheep (greater than or equal to 6 yr). Necrosis of the mandible was observed in five of eight rams and in one ewe. Corynebacterium pyogenes was cultured from exudates from two rams with enlarged fistulated mandibles. The sequence of events leading to lesions of the tooth arcade and to "lumpy jaw" is postulated to be associated with abnormal wearing of teeth and a disrupted alignment of the tooth arcade, impaction of vegetable matter between teeth and between the gingiva and the root of the tooth, and penetration of the traumatized gingiva membrane and alveolus by oral bacteria which induce a necrotizing infection.

Animal Feed↗