No abstract

Direct water mass renewal through convection deeper than 1000 m and the independent process of dense water production through brine rejection during sea ice formation occur at only a limited number of sites globally. Our late winter observations in 2000 and 2001 show that the Japan (East) Sea is a part of both exclusive groups. Japan Sea deep convection apparently occurs every winter, but massive renewal of bottom waters through brine rejection had not occurred for many decades prior to the extremely cold winter of 2001. The sites for both renewal mechanisms are south of Vladivostok, in the path of cold continental air outbreaks.

The Japan/East Sea is a major anomaly in the ventilation and overturn picture of the Pacifi c Ocean. The North Pacifi c is well known to be nearly unventilated at intermediate and abyssal depths, refl ected in low oxygen concentration at 1000 m (Figure 1). (High oxygen indicates newer water in more recent contact with the atmosphere. Oxygen declines as water "ages" after it leaves the sea surface mainly because of bacterial respiration.) Even the small production of North Pacifi c Intermediate Water in the Okhotsk Sea (Talley, 1991; Shcherbina et al., 2003) and the tiny amount of new bottom water encountered in the deep Bering Sea (Warner and Roden, 1995) have no obvious impact on the overall oxygen distribution at 1000 m and below, down to 3500 m, which is the approximate maximum depth of the Bering, Okhotsk, and Japan/East Seas. In contrast, the nearly isolated Japan/East Sea is very well ventilated at all depths from the surface to the bottom. Oxygen is higher than anywhere else in the Pacifi c, even in the South Pacifi c, where intermediate-layer ventilation yields relatively high oxygen content at 1000 dbar (roughly 1000-m depth). It is necessary to look much farther away, to the North Atlantic and best-ventilated sectors of the Antarctic, to fi nd deep ventilation comparable to the Japan/East Sea's. Because it is ventilated from top to bottom and located at mid-latitude, the Japan/East Sea has many similarities to the North Atlantic Ocean (e.g., Riser and Jacobs, 2005; Min and Warner, 2005). Both have (1) infl ow of warm, saline surface waters from the south; (2) subduction that ventilates the upper ocean in the subtropics; (3) subtropical mode waters; (4) a subpolar front south of which a low-salinity water mass is formed; (5) cooling and precipitation that cause a colder, fresher subpolar north; (6) subpolar mode waters with comparable winter mixed-layer thicknesses; and (7) deep convection and ice formation that ventilate the entire water column. The Japan/East Sea differs from the North Atlantic in two major respects: (1) the powerful northward eastern boundary current in the Japan/East Sea, the Tsushima Warm Current, distorts the subtropical gyre, and (2) the Japan/East Sea is isolated from all subsurface waters in the North Pacifi c. Therefore, the Japan/East Sea's salinity is nearly uniform below the shallow sill depth (140 m) of Tsushima Strait. The Japan/East Sea has a full temperature range, however, because surface waters cool to freezing and some of this very cold water becomes bottom water. In its isolation, the Japan/East Sea most closely resembles the Mediterranean Sea-both seas form dense water as a result of convection during winter cold-air outbreaks (Talley et al., 2003; Marshall and Schott, 1999).

SUMMARY Myeloid-biased hematopoietic stem cells (MB-HSCs) play critical roles in recovery from injury, but little is known about how they are regulated within the bone marrow niche. Here, we describe an auto/paracrine physiologic circuit that controls quiescence of MB-HSCs and hematopoietic progenitors marked by histidine decarboxylase (Hdc). Committed Hdc+ myeloid cells lie in close anatomical proximity to MB-HSCs and produce histamine, which activates the H2 receptor on MB-HSCs to promote their quiescence and self-renewal. Depleting histamine-producing cells enforces cell cycle entry, induces loss of serial transplant capacity, and sensitizes animals to chemotherapeutic injury. Increasing demand for myeloid cells via LPS treatment specifically recruits MB-HSCs and progenitors into the cell cycle; cycling MB-HSCs fail to revert into quiescence in the absence of histamine feedback, leading to their depletion, while an H2 agonist protects MB-HSCs from depletion after sepsis. Thus, histamine couples lineage-specific physiological demands to intrinsically-primed MB-HSCs to enforce homeostasis.

[1] This paper reports on a basin-wide inventory of anthropogenic CO 2 in the East (Japan) Sea determined from high-quality alkalinity, chlorofluorocarbon, and nutrient data collected during a summertime survey in 1999 and total dissolved inorganic carbon data calculated from pH and alkalinity measurements. The data set comprises measurements from 203 hydrographic stations and covers most of the East Sea with the exception of the northwestern boundary region. Anthropogenic CO 2 concentrations are estimated by separating this value from total dissolved inorganic carbon using a tracerbased (chlorofluorocarbon) separation technique. Wintertime surface CFC-12 data collected in regions of deep water formation off Vladivostok, Russia, improve the accuracy of estimates of anthropogenic CO 2 concentrations by providing improved airsea CO 2 disequilibrium values for intermediate and deep waters. Our calculation yields a total anthropogenic CO 2 inventory in the East Sea of 0.40 ± 0.06 petagrams of carbon as of 1999. Anthropogenic CO 2 has already reached the bottom of the East Sea, largely owing to the effective transport of anthropogenic CO 2 from the surface to the ocean interior via deep water formation in the waters off Vladivostok. The highest specific column inventory (vertically integrated inventory per square meter) of anthropogenic CO 2 of 80 mol C m À2 is found in the Japan Basin (40°NÀ44°N). Comparison of this inventory with those for other major basins of the same latitude band reveal that the East Sea values are much higher than the inventory for the Pacific Ocean (20À30 mol C m À2 ) and are similar to the inventory for the North Atlantic (66À72 mol C m À2 ). The substantial accumulation of anthropogenic CO 2 in the East Sea during the industrial era has caused the aragonite and calcite saturation horizons to move upward by 80À220 m and 500À700 m, respectively. These upward movements are approximately 5 times greater than those found in the North Pacific. Both the large accumulation of anthropogenic CO 2 and its significant impact on carbonate chemistry in the East Sea suggest that this sea is an important site for monitoring the future impact of the oceanic invasion of anthropogenic CO 2 .