John G. Coniglio

Incorporation of C14-acetate into intestinal fatty acids of rats with cannulated bile ducts.

Summary 1. Deprivation of bile flow to the rat intestine by means of cannulation of the bile duct did not affect the ability of the intestine to accumulate normal amounts of highly labeled fatty acids after administration of C14-acetate as shown by comparison with sham-operated, pair-fed controls. 2. Total radioactivity in the biliary fatty acids amounted to only 5-16% of the amount found in the intestinal fatty acids in the time periods studied. 3. Fatty acids of combined intestinal and cecal contents of cannulated animals contained more fatty acid but of a lower specific activity than those of control rats.

A comparative study of the lipid composition of isolated rat Sertoli and germinal cells.

The lipid composition of enriched preparations of sertoli cells and of germinal cells, isolated from the testes of mature rats, has been investigated. Sertoli cells contained a much lower content of phospholipids (in particular, much less phosphatidylcholine and phosphatidylethanolamine) and a higher content of triacylglycerols than did germinal cells. In addition, the Sertoli cells had a higher ratio of esterified to unesterified cholesterol than did germinal cells. Total lipids of Sertoli cells contained considerably lower levels of palmitic and docosa-4,7,10,13,16-pentaenoic acids and higher levels of stearic and oleic acids than did the total lipids of germinal less palmitic and docosa-4,7,10,13,16-pentaenoic acids, more stearic and oleic acids and also more arachidonic acid than did the corresponding lipid classes of the germinal cells. Minor differences between cell types were also noted for the content of palmitoleic, linoleic, docosa-7,10,13,16-tetraenoic, docosa-4,7,10,13,16,19-hexaenoic and tetracosa-9,12,15,18-tetraenoic acids.

Serum Lipids in Breast-Fed Infants and in Infants Fed Evaporated Milk

R ECENT investigations into the role of the lipid components of diets fed human infants have revealed a paucity of data concerning serum lipid patterns in infants fed the foods most commonly used in the United Stateshuman milk and evaporated whole cow’s milk. The purpose of the present study is to document the lipid patterns in infants fed these two diets between birth and six months of age, including as many lipids and lipid-soluble substances as could be readily measured when these studies were begun in 1957. The infants in this study were selected after interviewing mothers in the last trimester of pregnancy in the prenatal clinic at Vanderbilt Hospital and choosing those either planning to nurse their infants or willing to use the evaporated milk provided. Premature infants and twins were excluded from the study as were all infants having any illness other than mild infection of the respiratory tract. The infants were seen regularly in the Well Baby Clinic and in all growth, development and state of health were within the limits of clinical normal.

Polyunsaturated fatty acids in tissues of growing male and female rats

Abstract Polyunsaturated fatty acid concentrations of tissues were determined in male and female Sprague-Dawley rats of weanling, 3 months, and 6 months of age. No significant differences were found in concentrations of polyunsaturated fatty acids in corresponding tissues of male and female animals. Concentrations of polyunsaturated fatty acids in tissues of rats changed with age. The changes were different for each tissue and varied with the polyene concerned. Hexaenes comprised the greatest portion of polyunsaturated fatty acids in the brain of rats while dienes predominated in muscle and pentaenes in the testes. Tetraenes were in uniformly high concentrations in all organs and tissues studied and varied less with age than any of the other polyenes. Brain differed from other tissues in that it contained only trace amounts of dienes but relatively large quantities of tetraenes. In all tissues except brain a marked decrease was observed in hexaene concentration as animals matured from weanling to 6 months of age. Many of the tissues had lower tetraene and pentaene levels at 3 months than at either weanling or 6 months. The most marked change with age was the large increase in pentaene levels of testicular tissue between the ages of 3 weeks and 3 months.

The lipid composition of isolated rat spermatids and spermatocytes.

The lipids composition of enriched fractions of spermatids and spermatocytes, isolated from rat testicular tissue, has been investigated. More than 20% of the total fatty acids of spermatids but only 10% of those of spermatocytes, isolated from testes of mature rats, was 4,7,10,13,16-docosapentaenoic acid. Spermatocyte-enriched fractions isolated from testes of immature rats had fatty acid compositions similar to those isolated from testes of mature rats. On the other hand, spermatids isolated from immature rats had a level of docosapentaenoic acid which was intermediate between the level found in spermatocytes and that of spermatids from mature rats. Major phospholipid classes and the triacylglycerols of spermatids contained much more of the docosapentaenoic acid than the corresponding lipid types from spermatocytes. Differences in content of total phospholipids, individual classes of phospholipids and triacylglycerols among spermatocytes, spermatids and late spermatids were also observed.

Metabolism of eicosa-11,14-dienoic acid in rat testes evidence for Δ8-desaturase activity

The metabolism of [14C]eicosa-11,14-dienoic acid was investigated in rat testes in vivo and in vitro. Intratesticular injection of [1-14C]eicosa-11,14-dienoic acid resulted in the appearance of radioactivity (4-30% of 14C in total fatty acids) in 20-carbon trienoic fatty acids and a small amount (2-3.5%) in arachidonic acid. Analysis of the 20-carbon trienoic acid fraction by ozonolysis indicated that 15 to 34% of the 14C in this fraction was in an 8-carbon fragment originating from eicosa-8,11,14-trienoic acid. The rest (66 to 84%) was in a 5-carbon fragment, presumably originating from eicosa-5,11,14-trienoic acid. Incubation of testicular tissue minces or microsomes with [1-14C]eicosa-11,14-dienoic acid yielded labeled eicosa-8,11,14- and eicosa-5,11,14-trienoic acids in proportions similar to those obtained in vivo. Added unlabeled acetate had no effect on the formation of [14C]eicose-8,11,14-trienoic acid in vitro. Therefore, it is unlikely that the labeled eicosa-8,11,14-trienoic acid arose from elongation of octadeca-6,9,12-trienoic acid with labeled acetate derived from bio-oxidation of the labeled substrate. These results are compatible with a limited desaturation of eicosa-11,14-dienoic acid to eicosa-8,11,14-trienoic acid and provide evidence for delta8 desaturate activity in rat testis.

The metabolism of 4,7,10,13,16-(5-14C)docosapentaenoic acid in the testis of the rat.

Abstract The metabolism of [5-14C]docosapentaenoic acid, produced biosynthetically from [1-C]linoleic acid, was studied in rat testis at various time intervals after intratesticular injection. 14C-Labeled palmitic acid isolated from testicular total fatty acids indicated that significant catabolism of the intratesticularly injected [14C]docosapentaenoic acid had occurred. A significant proportion of the recovered radioactivity could be traced as arachidonic acid, which was shown by chemical degradation to have been biosynthesized in rat testis by the direct biohydrogenation and cleavage of the [5-14C]docosapentaenoic acid. 48 h after injection, 71% of the radioactivity recovered in the total fatty acids was in docosapentaenoate, 8% in arachidonate, and 5% in palmitate. These were present predominantly in esterified form as phosphatides and triglycerides.

The metabolism of polyunsaturated fatty acids in rat sertoli and germinal cells

The metabolism of [1-14C]linoleic, [1-14C]arachidonic and [3-14C]docosa-4,7,10,13,16-pentaenoic acids was investigated after intratesticular injection of the labeled compounds and isolation of rat Sertoli and germinal cells. Following injection of either14C-linoleate or14C-arachidonate, the specific activity (sp act) of docosa-4,7,10,13,16-pentaenoic acid of Sertoli cells was greater than that of the germinal cells. The data suggest that the Sertoli cells are more active in the biosynthesis of the 22-carbon pentaene than the germinal cells. Differences between these 2 cell types were also noted in the distribution of the incorporated14C among the various lipid classes. Following intratesticular injection of14C-docosapentaenoic acid, a greater proportion of the recovered14C in Sertoli cells than in germinal cells was present in 20-carbon fatty acids, suggesting a greater activity in Sertoli cells in the metabolism of the pentaene. The major portion of the recovered14C in both cell types was present in triacylglycerols during early time periods and in phospholipids after 24 hr. The possibility of transfer of biosynthesized docosapentaenoic acid from Sertoli to germinal cells is discussed.

The metabolism of linoleic and arachidonic acids in rat testis.

Linoleic and arachidonic acids, labeled with14C and injected intratesticularly, were used to study with time the interconversion of polyunsaturated fatty acids in rat testis and their incorporation into the major lipid classes. With both substrates14C activity was readily incorporated into longer chain, more highly unsaturated fatty acids. After the injection of 1-14C-linoleic acid the major portion of the14C was found in palmitic, linoleic, 8,11,14-eicosatrienoic, 5,8,11,14-eicosatetraenoic, 7,10,13,16-docosatetraenoic and 4,7,10,13,16-docosapentaenoic acids. Hydrogenation of the total fatty acids isolated from rat testes after intratesticular injection of 1-14C-linoleate revealed that the polyenoic acids hydrogenating to lignoceric acid (previously characterized as 9,12,15,18-tetracosatetraenoate and 6,9,12,15,18-tetracosapentaenoate) had a relatively high specific activity. After the injection of 1-14C-arachidonate significant14C activity was found in palmitate, 7,10,13,16-docosatetraenoate, 4,7,10,13,16-docosapentaenoate, 9,12,15,18-tetracosatetraenoate and 6,9,12,15,18-tetracosapentaenoate. The biosynthesis of the ω6 polyunsaturated fatty acids in rat testis is discussed in relation to these data. Investigation of the distribution of label in the complex lipid fractions demonstrated the majority of the14C activity to be present in phosphatides and triglycerides after injection of either of these14C substrates with only small quantities being present as nonesterified acids. At the time periods studied the polyenoic acids of triglycerides had a higher specific activity than the corresponding acids of phosphatides with the exception of linoleate.

Desaturation of eicosa-11,14-dienoic acid in human testes

The metabolism of [1-14C]eicosa-11,14-dienoic acid was investigated in human testes using whole tissue minces and microsomal preparations. Both types of preparations catalyzed the desaturation of the labeled diene to eicosa-8,11,14-trienoic as well as eicosa-5,11,14-trienoic acid. The reported results, therefore, indicate that human testicular tissue, as well as rat testicular tissue (reported previously), is capable of utilizing eicosa-11,14-dienoic acid as a precursor of arachidonic acid. Since it is known that there is no Δ8 desaturase activity in rat liver and brain, these studies support the concept that there is a tissue variation in this enzymatic pathway.