Axonal degeneration is a major cause of permanent deficit in inflammatory neurological diseases such as multiple sclerosis. Axons undergo degeneration specifically at the site of the inflammatory lesions, suggesting that locally produced inflammatory factors mediate the phenomenon. One such factor is nitric oxide (NO), which we have previously reported can cause reversible conduction block in axons. Here we confirm these observations and extend them to show that axons exhibit the early stages of wallerian degeneration if they are conducting impulses at physiological frequencies while they are exposed to the low micromolar concentrations of NO that are likely to occur at sites of inflammation. Rat dorsal roots were concurrently exposed in vivo to both NO and sustained impulse activity at 1, 50, or 100 Hz. Although our in vivo observations necessarily focused on the more acute responses, morphological examination of exposed roots at the end of the recording period revealed nodal and paranodal changes consistent with acute wallerian degeneration in roots stimulated at 50 or 100 Hz. This interpretation was confirmed in a few experiments that were prolonged to permit more obvious indicators of degeneration to develop. In these experiments the formation of myelin ovoids and frank axonolysis occurred in more than 95% of fibers. Roots stimulated at only 1 Hz appeared normal. We propose that the combination of normal impulse traffic and NO at sites of inflammation may cause axonal degeneration and that electrical activity may therefore be an important factor in causing permanent disability in patients with neuroinflammatory disorders.

An 8-yr time-series study of the trophic coupling between a pelagic food supply and its utilization by the sediment community was conducted at 4,100-m depth in the eastern North Pacific between 1989 and 1998. Supply of sinking particulate organic carbon (POC) and particulate total nitrogen (PTN) was estimated from collections made with sediment traps moored at 3,500-and 4,050-m depth (600 and 50 m above bottom). Sediment community oxygen consumption (SCOC), an estimate of aerobic utilization of organic matter, was measured in situ. POC and PTN fluxes at both depths declined significantly from October 1989 through 1996 then increased in 1998. Organic carbon : total nitrogen (C : N) of the sinking particulate matter fluctuated ϳ10 throughout the study, except for a major peak (84.8) at 50 m above bottom in summer 1995, indicating lateral advection of organic material of terrestrial origin. POC : SCOC declined progressively over the first 7 yr, from a high of 0.99 in 1989-1990 to 0.22 in 1995-1996. In 1998, there was an increase in POC : SCOC to 0.43, suggesting that the food deficit was reduced by an increase in sinking flux. A continuing deficit in food supply cannot be sustained without ultimately affecting the structural and functional characteristics of the sediment community. The importance of undersampling by sediment traps, lateral advection of marine and terrestrial organic matter from the continental slope and shelf, and dissolved organic matter is evaluated. These other sources of nutrients for benthic organisms may be important in explaining some of the observed discrepancy between supply and demand in the abyssal Pacific. Decadal-scale climate variations that influence marine primary production and terrestrial discharges into the ocean may be extremely important in understanding biogeochemical processes in the deep sea.The food supply for deep-sea benthic communities originates almost entirely from primary producers in surface waters and is transferred to the sea floor either directly, in the case of phytoplankton blooms, or indirectly, through the pelagic food web. Sediment traps have been employed routinely to measure the passive flux of sinking particulate organic matter (POM) in the water column as an estimate of food supply. Long time-series measurements of POM fluxes AcknowledgmentsThis long time-series research would not have been possible without the help of countless participants on our 36 cruises to Sta. M and the expertise of the ships' crews on RV New Horizon, RV Wecoma, RV Atlantis II/DSRV Alvin, and RV Sproul. We specifically thank our colleagues, Rob Glatts, Fred Uhlman, and Bob Wilson, for their support throughout this study. Critical comments by Ellen Druffel, Jeff Drazen, Henry Ruhl, and Anders Tengberg improved the manuscript. We especially thank Fred Sayles and Tim Shaw for providing valuable insights into the evaluation of our data and making the presentation significantly clearer; their constructive and in-depth comments were very thought-provoking.

We hypothesized that seasonal and interannual climate-mediated changes in particulate organic carbon (POC) flux would affect bioturbation and ultimately the sequestration of organic carbon in the deep sea. An 18-yr timeseries photographic record from 4100-m depth in the northeast Pacific Ocean showed increased abundance of Echinocrepis rostrata, a common epibenthic echinoid and bioturbator, since the late 1990s. Abundance, size, and speed data were used to estimate bioturbation potential to track long-term changes in the volume of sediment disturbed by E. rostrata. There was no secular increase in E. rostrata bioturbation over 18 yr despite increased population size, although periodic variations in bioturbation were significantly correlated with POC flux. Expected changes in POC flux and bioturbation rates due to climate variation could lead to altered rates of carbon sequestration in deep-sea sediments, affecting the global carbon cycle.

Two new species of glass sponge were discovered from the abyssal plain 200 km west of the coast of California (Station M). The sponges have similar gross morphology-an unusual plate-like form with basalia stilting the body above soft abyssal sediments. Bathydorus laniger sp. n. differs from its congeners by the presence of dermal and atrial stauractins; it is also supported by smooth hypodermal pentactins and hypoatrial hexactins. Microscleres include oxyhexasters and oxyhemihexasters. Docosaccus maculatus sp. n. contains large hexactins (>1 cm), characteristic of the genus. Megascleres include dermal hexactins, atrial pentactins, and choanosomal hexactins and diactins. Microscleres include oxytipped hemihexasters and floricomes. Several features serve to differentiate this species from its only known congener.

Animals must eat, necessitating their encounter with food. At least one of the two, predator or prey, must move for the two to meet. Many predators forage for prey by one of two strategies, or foraging modes. They forage either actively, in which case their prey may be mobile or sessile, or passively by waiting in ambush, depending on prey motility. These two foraging modes have been studied extensively in lizards as a model organism (Cooper 1995, Huey & Pianka 1981, Pianka 1966, Pietruzska 1986). Many aspects of a species' biology are correlated with its foraging mode. For example, active foragers employ their chemosensory apparatus for following the prey's trail. Sit-and-wait foragers rely on their eyes to identify approaching prey (Cooper 1995). Other differences are briefly referenced elsewhere (Werner et al. 1997, 2004).