Conjugate Fractions Research Articles

Low Fractions of Mono‐ and Diconjugated Bilirubin in Patients with β‐Thalassemia

SummaryUnconjugated and mono‐ and diconjugated bilirubin was determined by alkaline methanolysis and thin‐layer chromatography in serum from 16 pediatric patients with homozygous β‐thalassemia (aged 1–23 years), in 14 age‐matched controls, and in 26 healthy adults. Total bilirubin amounted to 21 ± 20 μmol/L in patients with thalassemia compared with 7 ± 4 μmol/L in healthy children and 11 ± 3 μmol/L in healthy adults. The fractions of bilirubin conjugates in the various groups were 8 ± 4% (patients with thalassemia), 18 ± 5% (age‐matched controls; p < 0.001), and 16 ± 5% (healthy adults; p < 0.001). The low fraction of bilirubin conjugates in patients with thalassemia showed no correlation to any other physical or laboratory finding. It is concluded that subnormal values of bilirubin conjugates in thalassemia indicate defective bilirubin conjugation.

Low Fractions of Mono- and Diconjugated Bilirubin in Patients with β-Thalassemia

Unconjugated and mono- and diconjugated bilirubin was determined by alkaline methanolysis and thin-layer chromatography in serum from 16 pediatric patients with homozygous beta-thalassemia (aged 1-23 years), in 14 age-matched controls, and in 26 healthy adults. Total bilirubin amounted to 21 +/- 20 mumol/L in patients with thalassemia compared with 7 +/- 4 mumol/L in healthy children and 11 +/- 3 mumol/L in healthy adults. The fractions of bilirubin conjugates in the various groups were 8 +/- 4% (patients with thalassemia), 18 +/- 5% (age-matched controls; p less than 0.001), and 16 +/- 5% (healthy adults; p less than 0.001). The low fraction of bilirubin conjugates in patients with thalassemia showed no correlation to any other physical or laboratory finding. It is concluded that subnormal values of bilirubin conjugates in thalassemia indicate defective bilirubin conjugation.

Studies on the Metabolic Fate of Mometasone furpate(MF). (IV). Metabolism in Rats and Rabbits.

14C-MFを0.5mg/kgの投与量で雌雄ラットおよび雄性ウサギに投与した際の血漿中，胆汁中および尿中の代謝物について検討した．代謝物の推定は一連の代謝物標品とのco-chromatographyによって行った．これら代謝物の構造から3通りの主代謝経路が考えられた．すなわち，1)21位Clの水酸基への変換，2)6β水酸化，3)17位furoyl基の脱離である．これらの反応が相前後して起こることにより種々の代謝物が生成された．

The chemical nature of sex attracting pheromones from the seminal vesicle of the African catfish, Clarias gariepinus

In attraction tests, ovulated female African catfish, Clarias gariepinus, were attracted by the administration of 2.0 ml/l seminal vesicle fluid to the aquarium water. Lower doses (0.1 and 0.5 ml/l) were ineffective, and a high concentration (8.0 ml/l) seemed to have a repulsive effect. After fractionation of the fluid, an isolated steroid conjugate fraction appeared to contain the attractant. No other stimuli beyond this fraction were required to attract groups of female catfish after ovulation. Other constituents of the fluid such as polysaccharides, proteins, phospholipids and steroids failed to attract the females. GCMS analysis of the steroid conjugate fraction revealed the presence of eight different steroid glucuronides. After removal of these steroid glucuronides, the steroid conjugate fraction lost its attractive effect. A mixture of seven available synthetic steroid glucuronides was composed according to the quantitative results of the GCMS analysis. This mixture appeared to have a powerful dose-dependent attractive effect on ovulated females. It is concluded that a combination of various steroid glucuronides, present in seminal vesicle fluid, functions as a sex attractant, bringing male and female African catfish together shortly before spawning.

Biotransformation of 1-dehydrotestosterone in the equine male castrate: Identification of the neutral unconjugated and glucuronic acid conjugated metabolites in horse urine

The in vivo biotransformation of (1,2(n)-3H)1-dehydrotestosterone was studied in three equine male castrates and a number of neutral metabolites were identified in the urinary unconjugated and glucuronic acid conjugate fractions by gas chromatography/mass spectrometry. The metabolites were extracted from aliquots of the 0-24 h urine samples by Amberlite XAD-2 and separated into combined unconjugated plus glucuronic acid conjugated and sulphoconjugated fractions by Sephadex LH-20 column chromatography. After enzymatic hydrolysis of the glucuronides, the crude neutral unconjugated steroids plus the aglycones were partially purified by Kieselgel H chromatography and identified as their methyloxime trimethylsilyl derivatives. In the unconjugated fraction, the major metabolites were isomers of androsta-1,4-diene-6,16,17-triol-3-one. In the aglycone fraction a small amount of the parent steroid was present but the major metabolite was the 17 alpha isomer androsta-1,4-dien-17 alpha-ol-3-one. Other metabolites containing the 1,4-dien-3-one group were isomers of androsta-1,4-diene-16,17-diol-3-one and androsta-1,4-diene-6,16-diol-3-one. Reduction of the 4-ene functionality leading to the formation of 5-androst-1-en-16-ol-3,17-dione, 5-androst-1-ene-16,17-diol-3-one and of the 1-ene functionality leading to the formation of testosterone and its further reduction leading to the formation of C19O2 and C19O3 androstane metabolites was observed. Some interesting features on the electron impact fragmentations of the methyloxime trimethylsilyl derivatives of steroids containing a 1,4-dien-3-one group were also observed.

Altered bile acid profiles in duodenal bile and urine in diabetic subjects.

The bile acid composition in duodenal bile was analysed in 22 diet-treated and 11 insulin-treated middle-aged patients with diabetes mellitus and in 20 normoglycaemic controls. In 10 subjects with diabetes mellitus the bile acid profile in urine was also investigated. In the non-insulin-dependent diabetic patients the percentage of cholic acid was reduced and that of deoxycholic acid increased. As a highly significant finding there was a three-fold increase of the percentage of 12-ketolithocholic acid in duodenal bile in non-insulin-dependent diabetics, whereas the bile acid composition in insulin-dependent diabetics was similar to that in a control group. The percentage of 12-ketolithocholic acid in duodenal bile was positively correlated to the percentage in urine. In nine of the subjects studied, 12-ketolithocholic acid was the major individual bile acid in urine. It constituted 36.3 +/- 4.4% of the bile acids analysed and the excretion was 6.1 +/- 2.3 mumol 24 h-1. Together with 3 alpha, 12 beta-dihydroxy-5 beta-cholanoic acid it was predominantly present in the glycine conjugate fraction, whereas in bile its conjugation was similar to that of the other bile acids. The results may reflect an increased formation of secondary bile acids from cholic acid combined with a metabolic disturbance in non-insulin-dependent diabetics affecting the oxidoreduction of bile acids at C-12.

Profile of free and conjugated ecdysteroids and ecdysteroid acids during embryonic development of Manduca sexta (L.) following maternal incorporation of [14C]cholesterol

AbstractThe levels of both free and conjugated ecdysteroids, maternally labeled from [14C]cholesterol, of six different age groups of Manduca sexta eggs were quantitatively determined. Eggs 0–1‐h old contain about 2.5 and 35 μ/g of the 2‐ and 26‐phosphates of 26‐hydroxyecdysone, respectively, and 1 μg/g of 26‐hydroxyecdysone. During embryogenesis of 26‐hydroxyedcdysone 26‐phosphate is hydrolyzed to 26‐hydroxyecdysone, which reaches a peak titer in 1–18‐h‐old eggs; the level of 26‐hydroxyecdysone 2‐phosphate remains rather constant. Additionally, other metabolic modifications such as hydroxylation, conjugation, epimerization, and oxidation are occurring; and as the level of the 26‐hydroxyecdysone 26‐phosphate decreases there is a progression of other ecdysteroids. C‐20 hydroxylation first appears in 24–40‐h‐old eggs and reaches peak activity in 48–64‐h‐old eggs, where 20‐hydroxyecdysone and 20, 26‐dihydroxyecdysone are both present at peak titer but the latter is the major free ecdysteroid. Ecdysone is observed at measurable levels only in the three age groups of eggs between 1 and 64 h‐old. C‐3 epimerase activity also appears at 24–40 h and continually increases throughout embryogenesis to the point that 3‐epi‐26‐hydroxyecdysone and 3‐epi‐20, 26‐dihydroxyecdysone are the major free ecdysteroids in 96‐h‐old eggs. A new ecdysteroid conjugate, 26‐hydroxyecdysone 22‐glucoside, first appears at 24–40h and becomes the major conjugate in 72–80‐h‐old eggs; it represents an apparent end‐product as its peak titer is reached and maintained throughout the final embryonic stages. 20‐Hydroxyecdysonoic acid occurs in 48–64‐h‐old eggs, and along with 3‐epi‐20‐hydroxyecdysonoic and ecdysonoic acids in 72–88‐h‐old eggs. 20‐Hydroxyecdysonoic acid peaks during the latter time interval, and as its titer subsequently falls, there is a concurrent increase in the level of 3‐epi‐20‐hydroxyecdysonoic which was identified as the second major component of the ecdysteroid conjugate fraction of 0–1‐h‐old larvae. Our results indicate that there is little or no biosynthesis of ecdysteroids during embryogenesis; that the materal ecdysteroid conjugate 26‐hydroxyecdysone 26‐phosphate serves as source for 26‐hydroxyecdysone and the numerous metabolites; that 26‐hydroxyecdysone and 20,26‐dihydroxyecdysone may be the active hormones during embryonic development; and that glucosylation, epimerization, and formation of acids cosntitute inactivation processes. A scheme of the proposed pathways involved in the metabolism of 26–hydroxyecdysone 26‐phosphate in the developing eggs of m. sexta is presented.

Poly(ADP-ribose) synthase is the major endogenous nonhistone acceptor for poly(ADP-ribose) in alkylated rat hepatoma cells.

The endogenous poly(ADP-ribosyl)--nonhistone protein conjugates were isolated from dimethyl-sulfate-treated rat hepatoma AH 7974 cells using aminophenylboronic-acid--agarose chromatography. Seven major components could be discerned on dodecyl sulfate gels (molecular mass 43, 60, 66, 86, 100, 110 and 170 kDa) while control cells indicated only slight staining at above 200 kDa. The most abundant conjugate formed in response to alkylation damage was further purified using preparative gel electrophoresis and identified on the basis of its intrinsic enzymic activity as automodified poly(APD-ribose) synthase. In addition, topoisomerase I activity was found associated with a 60-kDa peptide. ADP-ribosylated endonuclease and actin were not detect-able. The purified conjugate fraction contained maximally 8.8 nmol/mg ADP-ribose and 7.9 nmol/mg oligo(ADP-ribose) with a mean chain length of 2.3 residues. The modifying (ADP-ribosyl)n groups were attached to its acceptors by a hydroxylamine-insensitive bond and had practically no effect on the DNA affinity of either poly(ADP-ribose) synthase or topoisomerase I.

Metabolism of metalaxyl in cell suspension cultures of Lactuca sativa L. and Vitis vinifera L

The metabolic fate of metalaxyl in suspension cultures of Lactuca sativa has been investigated as a function of explant source, culture age, and nutrient medium quality. In all cases, the fungicide was the subject of diverse metabolic attack yielding products which arose from O- and N-dealkylation, alkyl and aryl hydroxylation, and ester hydrolysis. Substantial amounts of metabolites were found in the culture filtrates although products arising from aryl hydroxylation and combined O-/N-dealkylation accumulated exclusively as cellular conjugates. Cultures newly isolated from the cotyledon, hypocotyl, and root of seedlings displayed very little variation in the rate and qualitative nature of breakdown and in the relative distribution of metabolites among the polar conjugate fraction, unconjugated cellular fraction, and culture filtrate. Similarly, metabolism proceeded independently of changes in nutrient medium composition. A suspension culture initiated from 4-year-old hypocotyl callus produced less identifiable metabolites and had an impaired ability to perform alkyl hydroxylation, O-dealkylation, and ester hydrolysis. A greater proportion of metabolites occurred as polar conjugates in the 4-year-old hypocotyl cells than that in the newly isolated hypocotyl line. The metabolic profile seen in Vitis vinifera was similar to that in L. sativa and a time-course study indicated some interconversion of metabolites and a change in the ratio of two atropisomers formed by alkyl hydroxylation.

Unusual conjugates in biological profiles originating from consumption of onions and garlic

After consumption of onions or garlic, biological profiles of human urine samples show, in the methylated conjugate fraction, peaks corresponding to the methylates of N-acetyl-S-(2-carboxypropyl)cysteine ( 1), N-acetyl-S-allylcysteine ( 2) and hexahydrohippuric acid ( 3). The compounds 1 and 2 are metabolites of peptides introduced with onions or garlic into the body.

The fate of radiolabeled steroids in ovaries and eggs of the tobacco hornworm,Manduca sexta

To determine the precursors and the fate of 26-hydroxyecdysone in eggs, the fate of labeled putative ecdysteroid precursors was examined in the tobacco hornworm,Manduca sexta. Following injection of [(14)C]cholesterol, 22,25[(14)C]dideoxyecdysome or [(3)H]ecdysone into female pupae (day 16), only [(14)C]cholesterol was incorporated and metabolized. It was converted to labeled nonecdysteroid and ecdysteroid conjugates, of which the latter in ovaries and 48- to 64-hr-old eggs is mainly 26-hydroxyecdysone 26-phosphate (>85% in ovaries). Quantitation of the ecdysteroid conjugate by reversed-phase high performance liquid chromatography (RP-HPLC) showed that the levels of 26-hydroxyecdysone 26-phosphate were 31 μg/g of ovaries from 4-day-old females and 25 μg/g and 17 μg/g of 48- to 64-hr-old and 72- to 88-hr-old eggs, respectively. The RP-HPLC of the conjugate fraction of 48- to 64-hr-old eggs showed an additional peak of radioactive material eluting about three min before the 26-hydroxyecdysone 26-phosphate. The quantity of this material increased in the 72-to 88-hr-old eggs, though it was not detected in the analyses of the conjugate fraction from ovaries. Additional peaks of radioactive material eluting before the 26-hydroxyecdysone 26-phosphate peak were observed in the chromatogram of the conjugates of 72- to 88-hr-old eggs. These radioactive materials need to be identified to determine the ultimate fate of ecdysteroids in the developing embryos of the tobacco hornworm. No radioactive free ecdysteroids were detected in either egg age group.

The metabolism of phenothiazine in the neonatal calf: identification of drug-polypeptide conjugates from urine.

The presence of a polypeptide conjugate fraction in the urine of young calves after oral dosing with phenothiazine has been confirmed. Four different polypeptide conjugates, containing up to six amino acids attached to phenothiazine or leucophenothiazone via the carboxyl terminal of the chain, have been isolated, characterized and sequenced. In addition, several minor polypeptide conjugates have been observed. The literature pertaining to polypeptide conjugates of drugs has been reviewed and the importance of this metabolic route in neonatal animals discussed.

Validation of a radioimmunoassay for (+)-abscisic acid in extracts of apple and sweet-pepper tissue using high-pressure liquid chromatography and combined gas chromatography-mass spectrometry

A radioimmunoassay for (+)-abscisic acid (ABA) was developed and applied to the analysis of free ABA in extracts of apple (Malus pumila Mill.) and sweet pepper (Capsicum annuum L.) leaves at various stages during extract purification. Conjugates of ABA, were quantified after alkaline hydrolysis. The validity of the radioimmunoassay was tested by comparison of immunoassay estimates of ABA at different levels of extract purity with high-pressure liquid chromatography (HPLC) and combined gas chromatography-mass spectrometry. The antiserum, raised against (+)-ABA, was almost equally sensitive to (-)-ABA. Serum cross-reactivity with the methyl ester of ABA was 160% and with the glycosyl ester of ABA was 34%. Cross-reactivity with protein-ABA conjugates was very slight for C'4-conjugated keyholelimpet haemocyanin, but about 1000% for C1-conjugated alkaline phosphatase. Other compounds tested showed extremely low or undetectable cross-reactivities. Further evidence for the specificity of the assay came from the agreement between the results using different assay methods for both apple and pepper extracts, and from the observation that the only zone of immunoreactivity on HPLC elution profiles corresponded with authentic (+)-ABA. The use of polyvinylpyrrolidone in the assay minimised interference by other substances in plant extracts. In pepper, free ABA levels increased rapidly during water stress and recovered to pre-stress levels within two days after rewatering. Levels of ABA conjugates were significantly lowr than free ABA in unstressed plants, and also increased rapidly with stress, although not to the same extent as free ABA, and did not recover as rapidly as did free ABA. In apple, levels of free ABA and of ABA conjugates both increased more than twofold over a two-week period of water stress. In contrast to pepper, however, immunoreactivity of the conjugate fraction was increased by hydrolysis, indicating that different ABA conjugates predominate in the two species.

Comparison of faecal bile acid profiles between patients with adenomatous polyps of the large bowel and healthy subjects in Japan.

Faecal bile acid excretion was examined in 13 patients with adenomatous polyps of the large bowel and compared with a series of matched healthy subjects. Bile acids were analysed in detail with respect to the composition of individual bile acids and their mode of conjugation. The total excretion of bile acids by the patient group and the healthy subjects ranged from 55.0-837.6 mumol/day (median 233.8, mean 346.9) and 93.8-712.3 mumol/day (median 489.2, mean 386.7) respectively. Expressed as mumol/g faecal weight these values were 0.6-4.8 (median 2.2, mean 2.4) and 0.4-5.8 (median 2.2, mean 2.8) and in terms of mumol/g faecal dry weight, 1.9-50.7 (median 10.1, mean 16.5) and 3.9-32.4 (median 16.3, mean 16.7) respectively for the two groups. The composition of the individual bile acids and their distribution within the various conjugate fractions was essentially the same for both groups. Cholenoic acid (5 beta-chol-3-enoic acid), an unusual bile acid, was detected in one patient and three healthy subjects. These results revealed no significant quantitative differences in bile acid excretion between the group of patients with adenomatous polyps and those of healthy subjects.

Metabolism of androstenedione by Sertoli cell enriched preparations and purified leydig cells from boar testes in relation to estrogen formation

The metabolism of [ 3H]androstenedione in relation to estrogen formation was studied in incubations of Sertoli cell-enriched preparations (30–40% Sertoli cells) and purified Leydig cells (> 98%) from testes of mature male pigs. Radioactive metabolites were partitioned by countercurrent distribution (CCD) into unconjugated and ‘conjugated’ (water-soluble) fractions. Both unconjugated and solvolysed metabolites were separated into neutral and phenolic fractions by CCD with toluene and NaOH. The distribution of radioactivity was examined subsequently for each fraction by partition chromatography on celite columns. Major differences were noted in the products of metabolism from the two cell types. More than half of the radioactivity appeared in the conjugate fraction for Leydig cell incubations, but little or no conjugation occurred in Sertoli cell preparations. Metabolism of androstenedione to other neutral substances was extensive only for Leydig cells, with approx 2% remaining unchanged. No clear evidence of estrogen formation was observed with Sertoli cells; however, both unconjugated and conjugated phenolic fractions for Leydig cell products showed radioactivity corresponding to estrone and estradiol-17β on chromatography. About 2–5% of androstenedione was converted to these two estrogens, whereas most of the phenolic material was present as compounds more polar than estradiol.

Blockade of the galactose-binding sites of ricin by its linkage to antibody. Specific cytotoxic effects of the conjugates.

A method is described for preparing specific cytotoxic agents by linking intact ricin to antibodies in a manner that produces obstruction of the galactose-binding sites on the B chain of the toxin and so diminishes the capacity of the conjugate to bind non-specifically to cells. The conjugates were synthesised by reacting iodoacetylated ricin with thiolated immunoglobulin and the components of conjugate with reduced galactose-binding capacity were separated by affinity chromatography on Sepharose (a beta-galactosyl matrix) and asialofetuin-Sepharose. Fluorescence-activated cell sorter (FACS) analyses revealed that the fraction of a monoclonal anti-Thy1.1-ricin conjugate that passed through a Sepharose column had markedly diminished capacity to bind non-specifically to Thy1.2-expressing CBA thymocytes and EL4 lymphoma cells. The fraction of conjugate that passed through an asialofetuin-Sepharose column displayed no detectable non-specific binding. Both fractions of conjugate were potent cytotoxic agents for Thy1.1-expressing AKR-A lymphoma cells in tissue culture. They reduced the [3H]leucine incorporation of the cells by 50% at a concentration of 2-5 pM. Comparable inhibition of EL4 cells was only achieved with 3000-7500-fold greater concentrations of conjugate. By contrast, the fraction of anti-Thy1.1-ricin that retained Sepharose-binding capacity showed marked non-specific binding and toxicity to EL4 cells. A conjugate with diminished galactose-binding capacity was also prepared from the W3/25 monoclonal antibody which recognises an antigen upon helper T-lymphocytes in the rat. It elicited powerful and specific toxic effects upon W3/25 antigen-expressing rat T-leukaemia cells. This finding is of particular importance because isolated ricin A-chain disulphide-linked to W3/25 antibody is not cytotoxic. The property of the B-chain in intact ricin conjugates that facilitates delivery of the A-chain to the cytosol thus appears to be independent of galactose recognition. It is concluded that the 'blocked' ricin conjugates combine the advantages of high potency, which is often lacking in antibody-A-chain conjugates, with high specificity, which previously was lacking in intact ricin conjugates.

Mechanism of hydroxylation at C-2 during the biosynthesis of ecdysone in ovaries of the locust, Schistocerca gregaria.

The stereochemistry of hydroxylation at C-2 during the biosynthesis of ecdysone in the ovaries of Schistocerca gregaria was investigated by incorporation of [1 alpha,2 alpha-3H(n)]cholesterol in admixture with [4-14C]cholesterol into oöcyte 2-deoxyecdysone and ecdysone conjugates in maturing adult female S. gregaria. Extraction of the eggs followed by enzymic hydrolysis of the ecdysteroid conjugate fraction yielded free ecdysteroids, from which 2-deoxyecdysone and ecdysone were purified. The 3H/14C ratios in the 2-deoxyecdysone and ecdysone were similar, suggesting that the 2 alpha hydrogen of cholesterol was retained during hydroxylation at C-2. This was corroborated by oxidation at C-2 of the 3,22-diacetate derivative of the ecdysone, yielding the corresponding 2-oxo compound with removal of essentially all the 3H originally present at the 2 alpha position of cholesterol. The results indicate that the 2 beta hydrogen of cholesterol has been eliminated during the hydroxylation at C-2. Thus, during ecdysone biosynthesis, hydroxylation at C-2 is direct and occurs with retention of configuration.

Reversible Conjugation of Gibberellins In Situ in Maize

Gibberellins [(3)H]GA(4) (1.33 Curies per millimole) and [(3)H]GA(20) (2.36 Curies per millimole) were injected into the shanks of maize (Zea mays L.) cobs during rapid grain filling and mature seeds were subsequently harvested. Extracts of mature, dry seeds from 1980 feeds yielded only 20 to 30% of the (3)H radioactivity in acidic, ethyl acetate-soluble form, and this was principally associated with the precursor, with lesser amounts of the major metabolite, [(3)H]GA(1) (putative identification based on sequential SiO(2) partition, and gradient-eluted reverse-phase C(18) high performance liquid chromatography [HPLC]). Most of the radioactivity in the dry seeds was associated with compounds having partition characteristics of, and co-chromatographing on, sequential SiO(2) partition and reverse-phase HPLC with glucosyl conjugates of the precursors (GA(4) or GA(20)) and their probable major metabolite (GA(1)). The majority of conjugate associated with the precursor GA(4) eluted coincidental with GA(4) glucoside. Subsequent acid or enzymic hydrolysis (beta-glucosidase or cellulase) yielded the free GAs, putative identification being based on isocratic HPLC of each (3)H-labeled conjugate --> hydrolysis --> isocratic HPLC of the (3)H-labeled hydrolysate. Upon imbibition of the seeds, radioactivity associated with the conjugate fraction decreased; concomitantly, statistically significant increases in levels of free [(3)H]GA-like compounds were observed. Although the specific ratios of GA-like and GA-glucosyl conjugate-like substances varied substantially across years, hybrids, and even, in different plants from the same hybrid, this ;reversible conjugation' (i.e. apparent conjugation during seed maturation followed by release of the GA moiety during germination), was reproducible for [(3)H]GA(20) in seed from two maize hybrids produced over 2 years.

Glycolipids are not extracted from phospholipid bilayers by binding to ferritin-lectin conjugates

A radioactively-labelled glycosphingolipid, asialo-G M1, has been incorporated into phosphatidylcholine multilamellar vesicles. After incubation with ferritin- Ricinus communis agglutinin 60 (RCA 60) conjugate at different temperatures, the vesicles were separated from the conjugate by discontinuous density gradient ultracentrifugation. Measurement of the distribution of the radioactively-labelled asialo-G M1 in the pelleted conjugate fraction and freeze-etch electron microscopy of the vesicle fraction indicate that the decrease in labelling of asialo-G M 1 -containing vesicles by ferritin-RCA 60 conjugate with increasing temperatures (Tillack, T.W., Wong, M., Allietta, M. and Thompson, T.E. (1982) Biochim. Biophys. Acta 691, 261–273) reflects a decrease in apparent binding affinity rather than an ability of the conjugate to extract glycolipid from the phospholipid bilayer after binding.

Occurrence and seasonal variation of 19-norcholest-4-EN-3-one and 3β-monohydroxy sterols in the Californian gorgonian, [formula omitted

The first natural occurrence of 19-norcholestenone is reported, together with 17 sterols and one other Δ 4-3-ketone in the extracts of the Californian gorgonian, Muricea californica (Aurivillius). Six additional demethyl sterols and five additional 4-monomethyl sterols which remain unidentified were also detected. Lipid extracts of M. californica from a winter and summer collection were split by various chromatographic methods into free sterol, steryl ester, and steryl conjugate fractions. Sterol compositions (determined by GC and GC-MS) of each fraction, subsequent to hydrolysis, are tabulated and discussed with respect to plausible origins of observed variations. The possible relationship of the Muricea 19-nor-steroidal ketone to other naturally occurring 19-nor-steroids is discussed.