High-latitude controls of thermocline nutrients and low latitude biological productivity

The ocean's biological pump strips nutrients out of the surface waters and exports them into the thermocline and deep waters. If there were no return path of nutrients from deep waters, the biological pump would eventually deplete the surface waters and thermocline of nutrients; surface biological productivity would plummet. Here we make use of the combined distributions of silicic acid and nitrate to trace the main nutrient return path from deep waters by upwelling in the Southern Ocean and subsequent entrainment into subantarctic mode water. We show that the subantarctic mode water, which spreads throughout the entire Southern Hemisphere and North Atlantic Ocean, is the main source of nutrients for the thermocline. We also find that an additional return path exists in the northwest corner of the Pacific Ocean, where enhanced vertical mixing, perhaps driven by tides, brings abyssal nutrients to the surface and supplies them to the thermocline of the North Pacific. Our analysis has important implications for our understanding of large-scale controls on the nature and magnitude of low-latitude biological productivity and its sensitivity to climate change.     

Local metabolic response to physio-pathological demands: The pentose phosphate pathway

Résumé On a constaté dans le métabolisme de glucose une augmentation de l'utilisation de la voie oxydative directe dans la paroi de l'estomac durant la digestion, et dans celle des vaisseaux sanguins pendant inflammation, réparation et reconstruction. Les resultats ont été analysés en fonction de leur intérêt pour les problèmes cliniques.

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Investigation was conducted during tenure of Special Research Fellowship (No. 11091), U.S. Public Health Service.     

The michaelis constants of catheptic activity in xenopus tail tissue afterin vivo treatment with two leucine analogues

Zusammenfassung Die Michaelis-KonstanteKm der katheptischen Aktivität im Schwanzgewebe von Xenopuslarven wird durch das stark regenerationshemmende leucinanaloge Aminoketon E 9 nicht beeinflusst, obwohl nach 5 Tagenin vivo-Behandlung der Larven mit 3 · 10^–3 M E 9 ein starker Anstieg der spezifischen Kathepsinaktivität im Schwanzgewebe zu beobachten ist. Das leucinanaloge-Bromallylglycin (BAG) hemmt die Regeneration wenig, erhöht jedoch dieKm deutlich. Es wird postuliert, dass E 9 eine Zunahme der Kathepsine im Schwanzgewebe bewirkt, ohne die kinetischen Eigenschaften dieser Enzyme zu beeinflussen, während BAG an den aktiven Zentren der Kathepsine wirkt und die Affinität zum Substrat herabsetzt.

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With the aid of a grant from the Schweizerischer Nationalfonds zur Förderung der wissenschaftlichen Forschung. — Author's present address: Institut für experimentelle Gerontologie, Nonnenweg 7, Basel (Switzerland).     

Thein vitro inhibition of pentobarbital metabolism by chlorpromazine

Riassunto Si è osservato che il pentobarbital alla concentrazione di 2 × 10^–4 M può inibire per il 44% il metabolismoin vitro della cloropromazina alla medesima concentrazione.Si è discussa quindi la possibilità di inibire il metabolismoin vitro di alcuni farmaci propria di altre sostanze che vengono metabolizzate in maniera del tutto simile da sistemi enzimatici a livello microsomale epatico.