ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

Hits per page

hits 1 - 3 | 3 hits

Sorting

Electronic Resource

Survival of the intertidal pulmonate Onchidium tumidium during short term and long term anoxic stress (1996)

Lim, C. B. ; Low, W. P. ; Chew, S. F. ; [et al.]

Springer

Marine biology 125 (1996), S. 707-713

add to mindlist on the mindlist

Details

ISSN: 1432-1793

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Onchidium tumidium showed a triphasic response to anoxia. Twelve hours of anoxic exposure had no effect on the glycogen content in O. tumidium. However, there were significant increases in the alanine, lactate and succinate contents in the anoxic individuals. These were accompanied by a significant decrease in the ATP content. These results suggest that O. tumidium survived the first 12 h of anoxic exposure without increasing the glycolytic flux to compensate for the lower efficiency of ATP production through anaerobic pathways. Indeed, the fructose-2,6-bisphosphate (F-2,6-P2) content and the percentage of phosphofruc-tokinase (PFK) associated with the subcellular particles remain unchanged in O. tumidium exposed to 12 h of anoxia. Hence, a reduction in the metabolic rate of these individuals might have occurred during such a period of anoxia. In contrast, in between 12 and 24 h of anoxic exposure, the glycogen content O. tumidium decreased significantly, and levelled off thereafter. A significant increase in the percentage of PFK associated with the subcellular particles was observed in individuals exposed to 24 h of anoxia. In addition, the F-2,6-P2 content of these anoxic individuals increased significantly. Taken together, these two mechanisms could activate PFK and lead to a greater glycolytic flux. Beyond 24 h of anoxic exposure, survival of O. tumidium must have required considerable suppression of metabolism as accumulation of end products and depletions of glycogen and ATP had reached constant levels.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00349253

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

Electronic Resource

Different physiological functions of free D- and L-alanine in three body parts of the intertidal sipunculid Phascolosoma arcuatum (1996)

Low, W. P. ; Ong, W. T. ; Ip, Y. K.

Springer

Journal of comparative physiology 165 (1996), S. 558-564

add to mindlist on the mindlist

Details

ISSN: 1432-136X

Keywords: Alanine ; Amino acid ; Racemase ; Sipunculid ; Phascolosoma arcuatum

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Abstract Free D- and L-alanine contents were comparable in the body wall and introvert cum retractor muscles of Phascolosoma arcuatum. In contrast, the content of free D-alanine in the internal organs was twice that of free L-alanine. Since alanine aminotrans-ferase from P. arcuatum was L-alanine specific, D-alanine appeared to be synthesized from L-alanine through the action of alanine racemase. Alanine racemase activity was higher in the D-alanine-forming direction in the three body parts of P. arcuatum. In addition, the ratio of D→L/L→D racemase activity in the internal organs was the lowest among the body parts studied. These results indicate that free D-alanine might be of lesser importance than the free D-isomer to the internal organs as compared to the body wall and introvert cum retractor muscles. Indeed, L-alanine inhibited pyruvate kinase from the body wall and introvert cum retractor muscles but had no effect on the pyruvate kinase from the internal organs. Furthermore, the activity of alanopine dehydrogenase present in the internal organs was significantly lower than those of the body wall and introvert cum retractor muscles. L-Alanine was an essential substrate for alanopine formation in the body wall and introvert cum retractor muscles during hypoxia since alanopine dehydrogenases from these body parts were L-alanine specific. When P. arcuatum was confronted with hypo-osmotic stress, the free D-alanine/total free alanine ratio in the internal organs increased approximately from 0.6 to 0.8 as the total free alanine content decreased. In comparison, those ratios in the body wall and introvert cum retractor muscles remained relatively constant. It was concluded that D- and D-alanine had different physiological functions in the three body parts of P. arcuatum.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00387517

Permalink