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1

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Spermatozoa: models for studying regulatory aspects of energy metabolism (1996)

Kamp, G. ; Büsselmann, G. ; Lauterwein, J.

Springer

Cellular and molecular life sciences 52 (1996), S. 487-494

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ISSN: 1420-9071

Keywords: ATP-homeostasis ; phosphagen function ; NMR-spectroscopy ; spermatozoa ; sperm motility

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Abstract Spermatozoa are highly specialized cells, and they offer advantages for studying several basic aspects of metabolic control such as the role of adenosine triphosphate-(ATP)-homeostasis for cell function, the mechanisms of fatigue and metabolic depression, the metabolic channelling through the cytoplasm and the organization and regulation of glycolytic enzymes. Spermatozoa of four species with different reproductive modes are, introduced and the first results are presented: Spermatozoa of the marine wormArenicola marina are well adapted to external fertilization in sea water with fluctuating oxygen tension: they are motile for several hours in oxygen-free sea water, even when the ATP level is dramatically reduced. Anaerobic ATP production occurs by alanine, acetate and propionate fermentation probably by the same pathways known from somatic cells of this species. Under aerobic conditions the phosphagen system might function like a shuttle for energy-rich phosphate from mitochondria to the dynein-ATPases. Storage of turkey and carp spermatozoa for several hours without exogenous substrates and oxygen results in the degradation of phosphocreatine and ATP to inorganic phosphate and adenosine monophosphate (AMP), respectively. Despite low energy charges, stored spermatozoa of both species are capable of progressive movements. In carp spermatozoa fatigue of motility is not accompanied by the dramatic acidosis one discusses as an important effect in muscle fatigue. Energy metabolism of boar spermatozoa is typically based on glycolysis consuming extracellular carbohydrates and producing lactate and protons. The sperm seem to tolerate low intracellular pH (〈6.5). The lack of a phosphagen system (no energy shuttle from mitochondria to the distal dynein-ATPases) is probably compensated by a high glycolytic ATP-production in the mitochondria-free piece of the flagellum.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01919321

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2

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Phosphagen heterogeneity during reproductive cycle in the lugworm Arenicola marina (1989)

Kamp, G. ; Juretschke, H. -P.

Springer

Naturwissenschaften 76 (1989), S. 275-276

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ISSN: 1432-1904

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00368640

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3

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The Pasteur effect in facultative anaerobic metazoa (1996)

Schmidt, H. ; Kamp, G.

Springer

Cellular and molecular life sciences 52 (1996), S. 440-448

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ISSN: 1420-9071

Keywords: Facultative anaerobes ; metabolic depression ; Pasteur effect ; phosphofructokinase ; glycogen phosphorylase

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Abstract The existence and the regulatory mechanisms of the Pasteur effect in facultative anaerobic metazoa are discussed. There are three reasons for the controversy surrounding this phenomenon.1) The different definitions of the Pasteur effect,2) the antagonistic effect of metabolic depression and its species specific response to hypoxia, as well as3) the laboratory-specific differences in the experimental procedures for analyzing the Pasteur effect and its regulation. This review aims to clarify the confusion about the existence of the Pasteur effect in facultative anaerobic metazoa and to offer possible molecular mechanisms.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01919313

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4

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In vivo nuclear magnetic resonance studies on the lugworm Arenicola marina. I. Free inorganic phosphate and free adenylmonophosphate concentrations in the body wall and their dependence on hypoxia (1995)

Kamp, G. ; Juretschke, H. -P. ; Thiel, U. ; [et al.]

Springer

Journal of comparative physiology 165 (1995), S. 143-152

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ISSN: 1432-136X

Keywords: Hypoxia ; Regulation of glycogenolysis ; Inorganic phosphate ; Free adenosine monophosphate ; Lugworm, Arenicola marina

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Abstract The cytoplasmic concentrations of free inorganic phosphate and free AMP in the body wall of the lugworm Arenicola marina were estimated in order to verify their proposed regulatory role in glycogenolysis during anaerobiosis (Kamp 1993). Using in vivo 31P nuclear magnetic resonance spectroscopy the concentration of free inorganic phosphate was determined to be 4.7±0.7 mmol·1-1 (±standard deviation, n=3) varying with season (Juretschke and Kamp 1995). These values were two to three times lower than those measured in perchloric acid extracts. In contrast, values for the phosphagen phosphotaurocyamine assessed biochemically in the extracts and by in vivo nuclear magnetic resonance were very similar. During the transition from normoxia to hypoxia the concentration of free inorganic phosphate increased to the same extent and at the same rate as the concentration of phosphotaurocyamine decreased. A discrepancy was also found for the biochemically determined AMP and ADP concentrations in the extract and those derived from the equilibrium constants of the taurocyamine kinase (ADPfree) and adenylate kinase (AMPfree) reactions. Calculated concentrations of ADPfree and AMPfree in normoxic specimens were about two or even four orders of magnitude lower than the values determined in extracts. During hypoxia the concentrations of AMP and ADP increase moderately when measured biochemically in extracts, while the values for ADPfree and AMPfree rise three- and nine-fold during the first 3 h of hypoxia. Thereafter, the levels stay constant due to a progressive acidosis. If during hypoxia pHi is stabilized by addition of buffering substances to the incubation medium, both ADPfree and AMPfree rise continuously. The significant changes found for the concentrations of free inorganic phosphate and AMPfree support their assumed regulatory role in glycogenolysis during anaerobiosis, though these AMPfree values seem too low to actually activate glycogen phosphorylase. The strong effect of pHi on the levels of ADPfree and AMPfree suggest a mechanism by which acidosis prevents a continuing increase of glycogenolysis (ATP-producing pathway) during prolonged anaerobiosis (protective effect of acidosis).

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00301478

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In vivo nuclear magnetic resonance studies on the lugworm Arenicola marina. II Seasonal changes of metabolism (1995)

Juretschke, H. P. ; Kamp, G.

Springer

Journal of comparative physiology 165 (1995), S. 153-160

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ISSN: 1432-136X

Keywords: NMR spectroscopy ; Spermiogenesis ; Starvation ; Glycogen particles ; Lugworm, Arenicola marina

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Abstract In vivo 31P- and 13C-NMR spectra of the lugworm Arenicola marina (Polychaeta, Annelida) gathered between 1988 and 1994 at different times of the year were evaluated for seasonally dependent metabolic changes. Beside the typical 31P-NMR signals of ATP and (phospho)taurocyamine, other seasonally dependent signals were observed: from January to March an intensive signal at 1.4–1.8 ppm was identified as inorganic phosphate compartmented in an acidic intestinal lumen. Between April and September signals at 1.2–1.4 ppm were assigned to phosphodiester. Starting in July males showed a second phosphagen signal [(phospho)creatine of spermatozoa, cf. Kamp and Juretschke (1989a)] whose intensity increased until spawning in September. The (phospho)taurocyamine/ATP ratio was also dependent on the season. In January or February the ratio reached 11, while in summer and autumn the ratio was between 4 and 5. As verified by biochemical assays this effect was caused by a significant decrease of ATP in the lugworm body wall during winter (December–February). The phosphagen (phospho)taurocyamine and the respective unphosphorylated guanidine taurocyamine remained constant throughout the year. Levels of free inorganic phosphate incurred similar changes to ATP. 13C-NMR spectra of lugworms showed a dramatic change in lipid stores. They were below the detection limit between January and March but developed into the most intensive signals during summer. The most abundant amino acids, glycine and alanine, were observed throughout the year while glycogen could not be detected in the 13C-NMR spectra. After treating tissue extracts with amyloglucosidase, the signals of the hydrolytic product glucose were recorded indicative of NMR-invisible glycogen stores.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00301479

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6

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Comparison of the two different phosphagen systems in the lugworm Arenicola marina (1995)

Kamp, G. ; Englisch, H. ; Müller, R. ; [et al.]

Springer

Journal of comparative physiology 165 (1995), S. 496-505

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ISSN: 1432-136X

Keywords: Diffusion flux ; Glycogenolysis ; Phosphagen function ; Spermatozoa ; Lugworm, Arenicola marina

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Abstract The different phosphagen systems in the lugworm Arenicola marina, the phosphotaurocyamine/taurocyamine kinase system of the body wall and the phosphocreatine/creatine kinase system of the spermatozoa, have been investigated to answer the question whether the change reflects different functional modes of these phosphagen systems. Enzyme analyses have shown that in contrast to the body wall taurocyamine kinase, creatine kinase of spermatozoa exists in at least two different forms which are compartmented in the mitochondria (creatine kinase I) and in the flagellum (creatine kinase II). Creatine kinase I is strongly attached to cell structures which require detergents and high phosphate concentrations for solubilization. The affinities of taurocyamine kinase and creatine kinase for all substrates are very similar except the extremely high K m for creatine of both creatine kinase I and II. The level of creatine in spermatozoa is fivefold higher than taurocyamine in the body wall at similar phosphorylation potential (ATP/ADOfree) and ATP-buffer capacity (phosphagen/ATP), reflecting the higher equilibrium constants of the creatine kinase reaction compared to that of the taurocyamine kinase reaction (Ellington 1989). The high creatine concentration gives the phosphocreatine/creatine kinase system an advantage over the phosphotaurocyamine/taurocyamine kinase system for transport of energyrich phosphate at high phosphorylation potential by increasing the radial diffusion flux. The maximum diffusive flux of free ADP in spermatozoa is three orders of magnitude below the respiratory ATP production while the creatine flux would allow an unlimited energy transport over the long diffusion distance. In lugworm body wall, however, the low ATP turnover and the low diffusion distances between mitochondria and myosin-ATPases do not require a phosphagen shuttle.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00261305

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