Catalytic Properties of Two Pyruvate Kinase Isoforms in Nordic Krill, Meganyctiphanes norvegica, With Respect to Seasonal Temperature Adaptation

Metabolic cold adaptation in the lugworm Arenicola marina: comparison of a North Sea and a White Sea population

“…Comparatively little is known about the adjustment of aerobic metabolism during cold adaptation in marine invertebrates (Boyden 1972, Dahlhoff & Somero 1993, Vetter & Buchholz 1997. Sommer et al (1997) and Sommer & Pörtner (1999) studied the capacity and constraints of temperature adaptation in 2 populations (boreal and subpolar) of the lugworm Arenicola marina.…”

Physiology and Metabolism of Northern Krill (Meganyctiphanes norvegica Sars)

“…Dietary influence on a key metabolic enzyme: The influence of nutrition on the two PK-isoforms (PKI and PKII) of M. norvegica was studied by Salomon et al (2000) in specimens from the Ligurian Sea. Similar to Vetter and Buchholz (1997), the authors found two PK-isoforms. A common feature of Ligurian and Kattegat krill was the inhibition of PKI and PKII by ATP and the activation of PKII by fructose-1,6-bisphosphate (FBP), a key metabolite in the glycolytic pathway.…”

“…A common feature of Ligurian and Kattegat krill was the inhibition of PKI and PKII by ATP and the activation of PKII by fructose-1,6-bisphosphate (FBP), a key metabolite in the glycolytic pathway. Moreover, in the presence of FBP, the sigmoidal kinetics of PKII was shifted to hyperbolic kinetics (Vetter and Buchholz, 1997). Differences were apparent in the share of both isoforms in whole body extracts: PKI amounted to 80% in Ligurian krill, but only 44% in Kattegat krill.…”

“…This mechanism can be understood as an adaptation to the energy demanding pelagic life style of krill. PK-isoforms: In order to study physiological mechanisms of seasonal temperature adaptation Vetter and Buchholz (1997) isolated two isoforms of pyruvate kinase (PK) of M. norvegica from the Danish Kattegat. One isoform (PKI) dominated in the abdominal muscle while the other isoform, PKII, was mainly present in the cephalothorax.…”

“…Only PKI showed features of temperature adaptation by decreasing activation energy (E a ) and K M -values. Apparently, the requirement for temperature adaptation is more important in the energetically intensive swimming muscles of the abdomen (Vetter and Buchholz, 1997). Dietary influence on a key metabolic enzyme: The influence of nutrition on the two PK-isoforms (PKI and PKII) of M. norvegica was studied by Salomon et al (2000) in specimens from the Ligurian Sea.…”