Atlantic Water warming increases melt below Northeast Greenland's last floating ice tongue.

The 79 North Glacier (79NG) features Greenland's largest floating ice tongue. Even though its extent has not changed significantly in recent years, observations have indicated a major thinning of the ice tongue from below. Both ocean warming and an increase in subglacial discharge from the ice sheet induced by atmospheric warming could increase the basal melt; however, available observations alone cannot tell which of these is the main driver. Here, we employ a global simulation which explicitly resolves the ocean circulation in the cavity with 700 m resolution to disentangle the impact of the ocean and atmosphere. We find that the interannual variability of basal melt below 79NG over the past 50 years is mainly associated with changes in the temperature of the Atlantic Intermediate Water inflow, which can be traced back across the Northeast Greenland continental shelf to the eastern Fram Strait with a lag of 3 years.

Winners and Losers of Atlantification: The Degree of Ocean Warming Affects the Structure of Arctic Microbial Communities.

Arctic microbial communities (i.e., protists and bacteria) are increasingly subjected to an intrusion of new species via Atlantification and an uncertain degree of ocean warming. As species differ in adaptive traits, these oceanic conditions may lead to compositional changes with functional implications for the ecosystem. In June 2021, we incubated water from the western Fram Strait at three temperatures (2 °C, 6 °C, and 9 °C), mimicking the current and potential future properties of the Arctic Ocean. Our results show that increasing the temperature to 6 °C only minorly affects the community, while an increase to 9 °C significantly lowers the diversity and shifts the composition. A higher relative abundance of large hetero- and mixotrophic protists was observed at 2 °C and 6 °C compared to a higher abundance of intermediate-sized temperate diatoms at 9 °C. The compositional differences at 9 °C led to a higher chlorophyll a:POC ratio, but the C:N ratio remained similar. Our results contradict the common assumption that smaller organisms and heterotrophs are favored under warming and strongly indicate a thermal limit between 6 °C and 9 °C for many Arctic species. Consequently, the magnitude of temperature increase is a crucial factor for microbial community reorganization and the ensuing ecological consequences in the future Arctic Ocean.

Output properties and organization of the forelimb representation of motor areas on the lateral aspect of the hemisphere in rhesus macaques.

Motor output capabilities of the forelimb representation of dorsal motor area (PMd) and ventral motor area (PMv) were compared with primary motor cortex (M1) in terms of latency, strength, sign, and distribution of effects. Stimulus-triggered averages (60 microA) of electromyographic activity collected from 24 forelimb muscles were computed at 314 tracks in 2 monkeys trained to perform a reach-to-grasp task. The onset latency and magnitude of facilitation effects from PMd and PMv were significantly longer and 7- to 9-fold weaker than those from M1. Proximal muscles were predominantly represented in PMd and PMv. A joint-dependent flexor or extensor preference was also present. Distal and proximal muscle representations were intermingled in PMd and PMv. A gradual increase in latency and decrease in magnitude of effects were observed in moving from M1 surface sites toward more anterior sites in PMd. For many muscles, segregated areas producing suppression effects were found along the medial portion of PMd and adjacent M1. Although some facilitation effects from PMd and PMv had onset latencies as short as those from M1 in the same muscle, suggesting equal direct linkage, the vast majority had properties consistent with a more indirect linkage to motoneurons either through corticocortical connections with M1 and/or interneuronal linkages in the spinal cord.

Dietary arginine supplementation enhances the growth of milk-fed young pigs.

This study was conducted to determine the effect of dietary arginine supplementation on the growth of artificially reared piglets. The pigs (n = 24; 7 d old) were removed from sows to a nursery facility and assigned randomly to 1 of the 3 treatments representing diets supplemented with 0, 0.2, or 0.4% L-arginine (on the basis of milk replacer powder). Each milk feeder was assigned to 1 dietary treatment. Fresh liquid milk replacer (18.6% dry matter) was provided daily ( approximately 0800 h) to piglets. Body weights of piglets were measured and jugular venous blood samples were obtained for metabolite analysis at d 7, 14, and 21 of age. Food intake did not differ between control and arginine-supplemented piglets [66.7 vs. 69.5 g dry matter/(kg body wt. d)]. Compared with control piglets, dietary supplementation with 0.2 and 0.4% L-arginine dose dependently increased (P < 0.05) plasma concentrations of arginine by 30 and 61%, and decreased (P < 0.05) plasma concentrations of ammonia by 20 and 35%, and those of urea by 19 and 33%, respectively. Dietary supplementation with 0.4% L-arginine also increased (P < 0.05) plasma concentrations of insulin and growth hormone by 24-27% in piglets, compared with controls. Between 7 and 21 d of age, the supplementation of 0.2 and 0.4% L-arginine to piglets enhanced (P < 0.05) average daily weight gain by 28 and 66%, and body weight by 15 and 32%, respectively, compared with control piglets. Collectively, both the metabolic and growth data demonstrate unequivocally that arginine is deficient in milk-fed young pigs and that this arginine deficiency represents a major obstacle to maximal growth in piglets.