NN′-Diacetylchitobiase activity in Tay–Sachs disease and Sandhoff''s disease (Short Communication)

In Tay-Sachs disease and Sandhoff's disease respectively, one of the N-acetyl-beta-hexosaminidases (form A) or both (forms A and B) are absent, but glycosaminoglycans containing N-acetylhexosamines are not accumulated. The presence of NN'-diacetylchitobiase in livers from patients with these diseases raises the possibility that this new enzyme is involved in the metabolism of glycosaminoglycans rather than the enzymes previously described.     

Derivation of Population-Level Ecological Remedial Action Objectives: Tualatin River Case Study

In 1997, Oregon enacted rules that define an unacceptable population-level risk as a >10% chance of >20% of the total local population receiving an exposure greater than the toxicity reference value. This rule applies to populations of plants and animals not listed as threatened or endangered. An operational procedure was developed to perform such population-level ecological risk assessments. This case study describes how this procedure was used to develop site-specific groundwater remedial action objectives for resident aquatic populations at a site in Northwest Oregon, where an upland petroleum pipeline released gasoline-range hydrocarbons (TPH-G) into soils and groundwater immediately upgradient of the Tualatin River. With an interim response in place, the goal was to proactively establish a remedial action objective that would equate to an acceptable risk level for populations of aquatic receptors potentially threatened by future groundwater discharges to the river. Approximately 10 and 32% dilutions of the water-soluble fraction of pure product produced an acceptable risk level for zooplankton and forage fish populations, respectively. The proposed population-level remedial action objective, based on zooplankton as the most sensitive receptor, was a TPH-G groundwater concentration of 17.4?mg/L.     

The accuracy of scat identification in distribution surveys: American mink, Neovison vison, in the northern highlands of Scotland

Distribution data for elusive species are often based on detection of field signs rather than of the animal itself. However, identifying field signs can be problematic. We present here the results of a survey for American mink, Neovison vison, in the northern highlands of Scotland to demonstrate the importance of verifying field sign identification. Three experienced surveyors located scats, which they identified as mink scats, at seven of 147 sites surveyed and “possible” mink scats at a further 50 sites. Mitochondrial DNA was successfully extracted from 45 of 75 (60%) scats, collected from 31 of the 57 “positive” sites; sequencing of amplified DNA fragments showed that none of these scats was actually of mink origin. We consider the implications of erroneous survey data and the potential waste of resources and misdirection of conservation/management actions. We discuss potential methods that may be useful to verify field sign identification, including the use of DNA analysis, and stress that verification is crucial to ensure rigorous and reliable survey data.     

DURATION OF STEREOTYPED UNDERWATER VOCAL DISPLAYS BY MALE ATLANTIC WALRUSES IN RELATION TO AEROBIC DIVE LIMIT

During the breeding season from January to mid-April, adult male Atlantic walruses (Odobenus rosmarus rosmarus) dive repeatedly for an average duration of 4–6 min and give stereotyped underwater vocal displays. Between dives, they surface for 1–2 min, take 4–6 breaths, and give stereotyped vocalizations between breaths. Male walruses vocalize in the presence of groups of females and calves, young adult males, or by themselves as lone singers. This pattern is repeated throughout the breeding season and can be maintained for extended periods, sometimes exceeding 48 h. The prolonged underwater vocal displays of male walruses seem possible because the animals do not exceed the aerobic dive limit (ADL), estimated to be 9.8 min for a 1,100-kg animal, nor do they exceed the behavioral ADL of 7.9 min, determined from the histogram of dives for males singing alone. The number of breaths taken after dives and the postdive surface times remained fairly constant despite dive duration, suggesting that the walruses remained within their aerobic dive limits. The duration of most dives made by displaying males vocalizing alone during the breeding season, and dive duration of walruses feeding for protracted periods outside the breeding season, are both roughly half the estimated ADL.