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Comparative muscle growth in common and spotted wolffish
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COMPARATIVE
Abstracts / ComparativeBiochemisto,and Physiology, PartA 126 (2000)SI-SI63
MUSCLE GROWTH
IN COMMON
AND SPOTTED WOLFFISH
G a l l o w a y T.F.I and F a l k - P e t e r s e n I-B. 2 I Dept. o f Z o o l o g y , N o r w e g i a n U n i v e r s i t y o f S c i e n c e a n d T e c h n o l o g y , N - 7 4 9 1 T r o n d h e i m , N o r w a y 2 N o r w e g i a n C o l l e g e o f F i s h e r y S c i e n c e , U n i v e r s i t y o f TromsO, N - 9 0 3 7 Troms¢~, N o r w a y The common and spotted wolffish (Anarhichas lupus and A. minor, respectively) are becoming increasingly interesting as aquaculture species in northern Norway due to their tasty flesh, attractive skin and natural adaptation to the low water temperatures found in the area. Recent studies have shown that the two wolffish species have a very similar developmental biology and both need approximately 150 days from fertilisation until hatching at 5-8°C. At hatching both species are around 23 mm long and at a fairly advanced developmental stage. Despite these similarities, spotted wolffish larvae grow much faster than common wolffish larvae after hatching. The reasons for the different growth rates are not known but are likely to be related to growth of the swimming musculature, since this tissue constitutes more than 50% of the body mass. The objective of this study was to compare muscle growth in embryos and larvae of the common and spotted wolffish, and this poster presents preliminary results on the morphology of the swimming musculature in the two wolffish species. Both species had a well developed red layer surrounding the white muscle mass at hatching. In both species the red fibres were very rich in lipid vacuoles, but not so rich in mitochondria. Also, the red fibres were much larger in diameter than the white fibres. The white fibres were not homogenous in size; small fibres were found between larger fibres throughout the myotome. There did not appear to be any distinct germinal zones within the white muscle mass. In this respect the morphology of the swimming musculature in the common and spotted wolffish resembles that of salmonids more than that of small marine fish larvae at hatching, an observation that is in line with the wolffishes being at a more advanced developmental stage at hatching than marine pelagic fish larvae. The most noticeable difference in muscle morphology between the common and the spotted wolffish larvae was that the latter had more but smaller white muscle fibres at hatching. This may to some extent explain why the spotted wolffish grows faster than the common wolffish after hatching.
HIGH PRESSURE INACTIVATION OF HORA, FAMILY, IN LACTOBACILLUS PLANTARUM
A MDR
TRANSPORTER
OF THE ABC
G~inzle M . G . , U l m e r H . M . a n d V o g e l R.F. T U M t i n c h e n , L e h r s t u h l ftir T e c h n i s c h e M i k r o b i o l o g i e , D - 8 5 3 5 0 F r e i s i n g , G e r m a n y
Introduction. Inactivation of membrane-bound transport systems is considered a primary cause for sublethal injury and inactivation of micro-organisms under high pressure. We determined the high pressure (HP) inactivation of the beer spoiling isolate Lactobacillus plantarum TMW1.460, and investigated HP effects on the HorA activity of this organism. HorA is a membrane bound MDR transporter of the ABC-family conferring hop resistance to beer-spoiling lactic acid bacteria ( 1). Viability, metabolic activity, and membrane integrity of HP-treated cells. The kinetics of HP inactivation of L. plantarum TMW1.460 was determined and cells were characterized with respect to viability and metabolic activity. The integrity of the cytoplasmic membrane was determined with the fluorescent dye propidium iodide. During pressure holding time at 200 MPa, a lag-time of about 15 rain was observed where no loss of viability occurred, followed by exponential inactivation of the cells. The loss of metabolic activity correlated to cell death and membrane damage was observed later than cell death. Elimination of hop resistance by HP treatment. L. plantarum TMW1.460 was pressurized at 300 MPa to reduce viable cell counts by 90%. The survival of pressurized ceils in the presence of hop bitter compounds was compared to that of untreated ceils. Untreated cells tolerated the storage with hop bitter compounds, however, pressure treated cells were killed within 24 h of storage, indicating loss of hop resistance by sublethal HP treatment. HorA activity of HP-treated cells. The kinetics of HP inactivation of L. plantarum were further characterized by determination of HorA activity of HP-treated cells. HorA was inactivated during pressure treatment at 200 MPa without lag and loss of cell viability was observed only after complete HorA inactivation. To investigate whether membrane composition and fluidity affect HP inactivation of HorA, precultures of L. plantarum were prepared by incubation at 15°'C, 30°C, or 37°C to obtain cells with presumed variations in membrane composition, and cells were HP-treated under identical conditions, 200 MPa and 15°C. Remarkably, higher incubation temperatures of the precultures enhanced HorA stability as well as the pressure resistance of L. plantarum. Conclusions. Pressure treatment of L. plantarum inactivates HorA prior to cell death, resulting in loss of hop resistance. Pressure inactivation of HorA is appears to be affected by the composition of the cytoplasmic membrane. (1) van Veen, H.W., and W. Konings. 1998. Biochim. Biophys Acta 1365:31-36.
COMPARATIVE
Abstracts / ComparativeBiochemisto,and Physiology, PartA 126 (2000)SI-SI63
MUSCLE GROWTH
IN COMMON
AND SPOTTED WOLFFISH
G a l l o w a y T.F.I and F a l k - P e t e r s e n I-B. 2 I Dept. o f Z o o l o g y , N o r w e g i a n U n i v e r s i t y o f S c i e n c e a n d T e c h n o l o g y , N - 7 4 9 1 T r o n d h e i m , N o r w a y 2 N o r w e g i a n C o l l e g e o f F i s h e r y S c i e n c e , U n i v e r s i t y o f TromsO, N - 9 0 3 7 Troms¢~, N o r w a y The common and spotted wolffish (Anarhichas lupus and A. minor, respectively) are becoming increasingly interesting as aquaculture species in northern Norway due to their tasty flesh, attractive skin and natural adaptation to the low water temperatures found in the area. Recent studies have shown that the two wolffish species have a very similar developmental biology and both need approximately 150 days from fertilisation until hatching at 5-8°C. At hatching both species are around 23 mm long and at a fairly advanced developmental stage. Despite these similarities, spotted wolffish larvae grow much faster than common wolffish larvae after hatching. The reasons for the different growth rates are not known but are likely to be related to growth of the swimming musculature, since this tissue constitutes more than 50% of the body mass. The objective of this study was to compare muscle growth in embryos and larvae of the common and spotted wolffish, and this poster presents preliminary results on the morphology of the swimming musculature in the two wolffish species. Both species had a well developed red layer surrounding the white muscle mass at hatching. In both species the red fibres were very rich in lipid vacuoles, but not so rich in mitochondria. Also, the red fibres were much larger in diameter than the white fibres. The white fibres were not homogenous in size; small fibres were found between larger fibres throughout the myotome. There did not appear to be any distinct germinal zones within the white muscle mass. In this respect the morphology of the swimming musculature in the common and spotted wolffish resembles that of salmonids more than that of small marine fish larvae at hatching, an observation that is in line with the wolffishes being at a more advanced developmental stage at hatching than marine pelagic fish larvae. The most noticeable difference in muscle morphology between the common and the spotted wolffish larvae was that the latter had more but smaller white muscle fibres at hatching. This may to some extent explain why the spotted wolffish grows faster than the common wolffish after hatching.
HIGH PRESSURE INACTIVATION OF HORA, FAMILY, IN LACTOBACILLUS PLANTARUM
A MDR
TRANSPORTER
OF THE ABC
G~inzle M . G . , U l m e r H . M . a n d V o g e l R.F. T U M t i n c h e n , L e h r s t u h l ftir T e c h n i s c h e M i k r o b i o l o g i e , D - 8 5 3 5 0 F r e i s i n g , G e r m a n y
Introduction. Inactivation of membrane-bound transport systems is considered a primary cause for sublethal injury and inactivation of micro-organisms under high pressure. We determined the high pressure (HP) inactivation of the beer spoiling isolate Lactobacillus plantarum TMW1.460, and investigated HP effects on the HorA activity of this organism. HorA is a membrane bound MDR transporter of the ABC-family conferring hop resistance to beer-spoiling lactic acid bacteria ( 1). Viability, metabolic activity, and membrane integrity of HP-treated cells. The kinetics of HP inactivation of L. plantarum TMW1.460 was determined and cells were characterized with respect to viability and metabolic activity. The integrity of the cytoplasmic membrane was determined with the fluorescent dye propidium iodide. During pressure holding time at 200 MPa, a lag-time of about 15 rain was observed where no loss of viability occurred, followed by exponential inactivation of the cells. The loss of metabolic activity correlated to cell death and membrane damage was observed later than cell death. Elimination of hop resistance by HP treatment. L. plantarum TMW1.460 was pressurized at 300 MPa to reduce viable cell counts by 90%. The survival of pressurized ceils in the presence of hop bitter compounds was compared to that of untreated ceils. Untreated cells tolerated the storage with hop bitter compounds, however, pressure treated cells were killed within 24 h of storage, indicating loss of hop resistance by sublethal HP treatment. HorA activity of HP-treated cells. The kinetics of HP inactivation of L. plantarum were further characterized by determination of HorA activity of HP-treated cells. HorA was inactivated during pressure treatment at 200 MPa without lag and loss of cell viability was observed only after complete HorA inactivation. To investigate whether membrane composition and fluidity affect HP inactivation of HorA, precultures of L. plantarum were prepared by incubation at 15°'C, 30°C, or 37°C to obtain cells with presumed variations in membrane composition, and cells were HP-treated under identical conditions, 200 MPa and 15°C. Remarkably, higher incubation temperatures of the precultures enhanced HorA stability as well as the pressure resistance of L. plantarum. Conclusions. Pressure treatment of L. plantarum inactivates HorA prior to cell death, resulting in loss of hop resistance. Pressure inactivation of HorA is appears to be affected by the composition of the cytoplasmic membrane. (1) van Veen, H.W., and W. Konings. 1998. Biochim. Biophys Acta 1365:31-36.