- Email: [email protected]
Metabolic interrelationship between blood and milk lipids in the lactating dairy cow
Abstracts of Papers m a d e of the rate of labelling of various components of the animals' semen, samples being collected every 2-3 days. When labelled phosphate was administered. the first radioactive component to appear was always seminal plasma glycerylphosphorylcholine, reaching maximal specific activity at approximately 15-17 days. Next appeared the sperm phospholipids, acidsoluble P and "ribonucleic acid," all having maxima at about 23-26 days, and finally the sperm deoxyribonucleic acid at 50-57 days. When the connection between the testis and epididymis was removed surgically, labelling of the seminal plasma glycerylphosphorylcholine occurred normally, whereas the epididymal sperm were not labelled except in the acidsoluble fraction. W h e n labelled stearic acid was administered along with phosphate the main C 14 specific activity peak coincided with that of the sperm p52 phospholipids, but there was no peak corresponding to glycerylphosphorylcholine. T h e observations indicate that with this frequency of ejaculation the sperm take a m i n i m u m of about 11 days to pass through the epididymis before ejaculation. The time interval between the phospholipid peak and deoxyribonucleic acid peak probably represents the time taken for the spermatids to change into the spermatozoa, a process which does not involve the formation of new deoxyribonucleic acid. The glycerylphosphorylcholine of semen arises in the epididymis during the process of sperm maturation, but its production does not seem to be associated with the transfer of fatty acids to the sperm. 116
Metabolic Interrelationship between Blood a n d M i l k L i p i d s in t h e L a c t a t i n g D a i r y C o w . R . F. GLASCOCK, D. J . M c W E E N Y , a n d R . W . SMITH, N a t i o n a l I n s t i t u t e for R e s e a r c h in D a i r y i n g , R e a d i n g , U . K . Circulating lipids of the dairy cow fall chiefly in the following classes: glycerides, free fatty acids, phospholipids, cholesterol and cholesterol esters. It has already been shown in work from this laboratory that tritium-labelled stearic acid administered orally in the free state or as neutral fat appears very rapidly in the milk and within 14 days up to 60 per cent of the dose will have been collected. The way in which fat is transported from the gut to the milk is clearly of interest. Further work has now been done in which labelled stearic acid has again been administered by mouth and the circulating lipids of the blood then collected at intervals, fractionated and specific activity/time curves constructed both for them and for the milk lipids. From this data the compounds in the fat responsible for transporting fatty acids from gut to milk can be identified. Attempts have also been made
223
to label the circulating glycerides by administering tracer doses of tritium-labelled glycerides intravenously in the form of an emulsion, with particle size llt or less. It was found that only 10 per cent of administered activity was circulating, showing that some 90 per cent of the injected dose was treated as an unphysiological blood constituent. By comparing the specific activity/time data of the residual activity with that obtained from orally administered labelled fat an indication of the usefulness of this technique for labelling circulating lipids can be obtained. 117
I n c o r p o r a t i o n of B u t y r a t e 1-C l'I into M i l k C o n s t i t u e n t s by t h e P e r f u s e d C o w ' s U d d e r . M . LAURYSS~NS, R . V~RBEKE, a n d G. PEETERS, P h y s i o l o g i c a l D e p t . , V e t e r i n a r y College, University of Ghent, Belgium. The udder of a lactating cow was perfused with blood containing 1-C 14 butyrate (1 /~,c) for 2 hr. dJ In order to depress fatty acid breakdown, inactive butyrate and acetate were added respectively at the 80th and 105th minute. 5.7 per cent of the added activity was recovered as C O 2. Fatty acid fractions from the udder tissue were isolated. {2) The lower even-numbered fatty acids up to caprylic acid were separated by gas-liquid chromatography. (a~ The higher even-numbered fatty acids were separated by reversed phase partition chromatography.*4 The results obtained show that the m a m m a r y gland utilises butyrate for fat synthesis. The specific activity of the lower fatty acids--starting with acetic up to capric acid--increases with increasing chainlength to reach a m a x i m u m at capric acid. From capric up to stearic acid the specific activity fell progressively with increasing chain-length. Butyrate is also incorporated into glycerol, lactose, phospholipids and milkcasein. T h e aminoacids of the casein-fraction were isolated. ('5) Highest activity was detected in glutamic and aspartic acid. Serine, proline, glycine and alanine were slightly radioactive. The fact that the specific activity of glutamic acid is 5 times as high as the activity of aspartic acid indicates that butyrate is catabolized via acetate. References 1. PETERS G. and MASSART L. Arch. Int. Pharmacod. Ther. 74, 83 (1947). 2. POPIAK G., FRENCHT. IL, and FOLLEYS.J. Biochem. o7. 48, 4II (1951). 3. JA~l~s A. T. and MARTIN A. J. P. Biochem. 07. 50~ 679 (1952). 4. HOWARDG. A. and MARTINA. J . P . Biochem. J. 46, 532 (1950). 5. Hms C. H. W., MooRe S., and STEINW . H . J. Amer. Chem. Soc. 76, 6063 (1954).
Metabolic Interrelationship between Blood a n d M i l k L i p i d s in t h e L a c t a t i n g D a i r y C o w . R . F. GLASCOCK, D. J . M c W E E N Y , a n d R . W . SMITH, N a t i o n a l I n s t i t u t e for R e s e a r c h in D a i r y i n g , R e a d i n g , U . K . Circulating lipids of the dairy cow fall chiefly in the following classes: glycerides, free fatty acids, phospholipids, cholesterol and cholesterol esters. It has already been shown in work from this laboratory that tritium-labelled stearic acid administered orally in the free state or as neutral fat appears very rapidly in the milk and within 14 days up to 60 per cent of the dose will have been collected. The way in which fat is transported from the gut to the milk is clearly of interest. Further work has now been done in which labelled stearic acid has again been administered by mouth and the circulating lipids of the blood then collected at intervals, fractionated and specific activity/time curves constructed both for them and for the milk lipids. From this data the compounds in the fat responsible for transporting fatty acids from gut to milk can be identified. Attempts have also been made
223
to label the circulating glycerides by administering tracer doses of tritium-labelled glycerides intravenously in the form of an emulsion, with particle size llt or less. It was found that only 10 per cent of administered activity was circulating, showing that some 90 per cent of the injected dose was treated as an unphysiological blood constituent. By comparing the specific activity/time data of the residual activity with that obtained from orally administered labelled fat an indication of the usefulness of this technique for labelling circulating lipids can be obtained. 117
I n c o r p o r a t i o n of B u t y r a t e 1-C l'I into M i l k C o n s t i t u e n t s by t h e P e r f u s e d C o w ' s U d d e r . M . LAURYSS~NS, R . V~RBEKE, a n d G. PEETERS, P h y s i o l o g i c a l D e p t . , V e t e r i n a r y College, University of Ghent, Belgium. The udder of a lactating cow was perfused with blood containing 1-C 14 butyrate (1 /~,c) for 2 hr. dJ In order to depress fatty acid breakdown, inactive butyrate and acetate were added respectively at the 80th and 105th minute. 5.7 per cent of the added activity was recovered as C O 2. Fatty acid fractions from the udder tissue were isolated. {2) The lower even-numbered fatty acids up to caprylic acid were separated by gas-liquid chromatography. (a~ The higher even-numbered fatty acids were separated by reversed phase partition chromatography.*4 The results obtained show that the m a m m a r y gland utilises butyrate for fat synthesis. The specific activity of the lower fatty acids--starting with acetic up to capric acid--increases with increasing chainlength to reach a m a x i m u m at capric acid. From capric up to stearic acid the specific activity fell progressively with increasing chain-length. Butyrate is also incorporated into glycerol, lactose, phospholipids and milkcasein. T h e aminoacids of the casein-fraction were isolated. ('5) Highest activity was detected in glutamic and aspartic acid. Serine, proline, glycine and alanine were slightly radioactive. The fact that the specific activity of glutamic acid is 5 times as high as the activity of aspartic acid indicates that butyrate is catabolized via acetate. References 1. PETERS G. and MASSART L. Arch. Int. Pharmacod. Ther. 74, 83 (1947). 2. POPIAK G., FRENCHT. IL, and FOLLEYS.J. Biochem. o7. 48, 4II (1951). 3. JA~l~s A. T. and MARTIN A. J. P. Biochem. 07. 50~ 679 (1952). 4. HOWARDG. A. and MARTINA. J . P . Biochem. J. 46, 532 (1950). 5. Hms C. H. W., MooRe S., and STEINW . H . J. Amer. Chem. Soc. 76, 6063 (1954).