Age- and density-dependent growth within populations of the ectoparasitic digenean Transversotrema patialense on the fish host

Mills C. A. 1980. Age- and density-dependent growth within populations of the ectoparasitic digenean Transversotrema patialense on the fish host. Internationaljournal for Parasitology, 10: 287–291. Growth of the adult ectoparasitic digenean Transversotrema patialense on the fish host Brachydanio rerio is shown to be age-dependent, ceasing 15–20 days post infection. The vitelline glands expand greatly in size after infection from 1.25 % of cercarial area to 20.7 % of that of the mature adult. There is an increase in the occurrence of reproductive abnormalities in old parasites but this alone fails to account for the decline in egg production found as populations of T. patialense age. Growth of adult T. patialense is density-dependent with reduced growth at high initial parasite densities per host.     

Egg capsule dimensions as a taxonomic criterion in the digenean family transversotrematidae

Egg capsule morphometrics of the ectoparasitic digenean Transversotrema patialense are examined. Capsule width, but not length, shows age-dependency over the ovigerous life span of the fluke at 24°C. Capsule length is normally distributed. A comparison between 7 species of the family Transverso-trematidae indicates that the published data on egg dimensions are inadequate for statistical analyses. Simple methods for strengthening the role of egg capsule dimensions in numerical taxonomy are suggested.     

Temporal variability in egg production rates of Acartia tonsa Dana in Long Island Sound

The relationship between week-by-week variations in the in situ egg production rates of Acartia tonsa Dana and changes in chlorophyll concentration in several size fractions was investigated by incubating adult females in natural sea water for 24-h periods. Our results indicate that the egg production of A. tonsa in Long Island Sound was better related to the 10 μm chlorophyll size fraction than to the total chlorophyll concentration. The < 10 μm size fraction comprised the greatest percentage of the chlorophyll during July and August when the water column was stratified. Egg production rates were lowest (8.7 eggs · female⁻¹ · day⁻¹) in early August when less than 0.5 μg chlorophyll 1 ⁻¹ was observed in the 10 μm chlorophyll a size fraction. Following destratification in late August, the “fall” diatom bloom occurred and egg production rates increased to the maximum observed rate of 56.6 eggs · female⁻¹ · day⁻¹. At this time, the concentration of the 10μm chlorophyll size fraction was 5.5 μg 1⁻¹. Maximum egg production rates were observed at chlorophyll concentrations as low as 0.8 μg 1⁻¹ in the 10 μm size fraction.     

Differential pulse polarographic determination of plasma menadione

A differential pulse polarographic assay for plasma vitamin K₃ (menadione) has been developed. Details of the assay are (i) lipid-soluble material is extracted from plasma into ether by the method of Bjornsson et al. [(1978) Thromb. Haemostas.2, 466–473]; (ii) ether is evaporated under nitrogen and the residue is dissolved in the supporting electrolyte, methanol: 0.2 m borate buffer (9:1), pH 6.8; (iii) current height is measured at ?0.32 V vs SCE on the differential pulse polarogram. The lower sensitivity limit of this technique after addition of standard vitamin K₃ to plasma is 0.3 μm; the calibration curve is linear from 0.6 through 10 μm. Two patients treated with a single dose of menadiol sodium diphosphate, 20 mg/M² i.m., achieved measurable plasma vitamin K₃ levels at 0.5 to 1.0 h ranging between 0.5 (0.08 μg/ml) and 2 μm (0.3 μg/ml).     

Vesicle involvement in the egg cortical reaction of the horseshoe crab,Limulus polyphemus L

Ultrastructural observations (TEM) of the cortical reaction in Limulus polyphemus have been difficult to obtain due to the relative impermeability of the transparent egg envelope to standard fixatives. With the application of trialdehyde fixation techniques [Kalt, M. R., and Tandler, B. (1971). J. Ultrastruct. Res.36, 633–645], the cortical reaction has now been examined and the role of cortical vesicles has been determined. The size of these vesicles in uninseminated eggs is heterogeneous, with small vesicles (0.5 μm) being apposed to the plasmalemma and with large vesicles (4 μm) located in a lower layer of the egg cortex. The contents of the small vesicles are translucent under the electron beam. With the onset of egg activation these vesicles fuse with the overlying plasmalemma. The contents of the large vesicles appear electron dense and exhibit distinctly different morphologies. Shortly after insemination these large vesicles begin to enlarge by fusing together. By 9 min after insemination some enlarged vesicles fuse with the plasmalemma to form pits on the egg surface. The remaining enlarged vesicles continue to fuse with the plasmalemma until approximately 60 min after insemination when few vesicles are remaining.     

Ultrastructure of the Z organ in Xiphinema ifacolum

Bieve-Zacheo T., Zacheo G. and Lamberti F. 1985. Ultrastructure of the Z organ in Xiphinema ifacolum. International Journal for Parasitology15: 453–461. The uterus in Xiphinema ifacolum can be divided into uterus proper, a 77 μm long tube and a lemon-shaped Z organ, about 28 μm long and 18 μm wide, placed between the oviduct and the uterus proper. The Z organ consists of a thick outer muscular layer of 120 cells, arranged in 20 rings of six cells each and a thin inner epithelium layer, lining the lumen. The epithelial cell walls, lining the lumen of the Z organ are thicker than those lining the uterus proper and are strongly folded. The crests of some of these folds carry six large apophyses, all about the same size and shape, these occupy the full length of the organ, becoming thicker towards the center of the lumen. There are many tubules near the surfaces of the apophyses, the contents of which can be dissolved by treatment with pepsin and pronase, indicating that they are proteins. This material probably consists of secretions which are squeezed out of the apophyses by a passing egg and may function in the formation or hardening of the egg shell.     

A submicrometer glass-membrane pH microelectrode.

The glass-membrane pH microelectrode (GMpHME) described previously (Anal. Biochem.73, 501, 1976) had a limitation in the minimum size (tip diameter) that could be manufactured (about 1 μm). In addition, when made at this small size the electrical resistance was usually high (10¹¹ Ω) and the response time long (greater than 5 min). The inability to manufacture the GMpHME with tip diameters less than 1 μm was primarily due to the thickness of the pH glass used to form the H⁺-sensitive membrane. In this report we detail a method for thinning the pH glass in such a way that the manufacture of submicrometer glass-membrane pH microelectrodes is possible. These submicrometer pH electrodes have rapid response times (1 to 3 min) and maintain the desirable characteristics of all GMpHMEs, that is, near theoretic slope and a well-defined sensing surface area.     

Age, distribution and abundance of viable resting eggs of Acartia pacifica (Copepoda: Calanoida) in Xiamen Bay, China

The distribution and abundance of viable resting eggs of copepod Acartia pacifica in Xiamen Bay, China, were determined in the laboratory by the presence of nauplii hatched from the sediments. Sediment cores to a depth of 30 cm, sliced at 1.0 cm intervals, showed that most viable resting eggs of A. pacifica occurred near the sediment surface (0-5 cm), and the number of viable eggs sharply decreased with depth of the sediment, although resting eggs remained viable as deep as 23 cm. ²¹⁰Pb analyses of the sediments indicated that the maximum age of viable eggs of A. pacifica was 20.5 years and the mean egg age was 4.3 years. The egg mortality of A. pacifica in the sediment was 0.1408 year⁻¹, or 85.92% annual egg survival, calculated by regressing ln(egg density) on the age of the sediment. The horizontal distribution of viable resting eggs ranged from 2.27×10³ to 3.85×10⁵ m⁻², with a mean value of 9.49×10⁴ m⁻². Regressions between viable eggs of A. pacifica and all fine-fraction particle size classes (at 2 μm intervals) were not significant. The accumulation of viable resting eggs that can persist for an extended period of time provided evidence for the existence of an egg bank of A. pacifica in the seabed of Xiamen Bay.     

The effects of extenders and sperm‐egg ratios on fertilizing ability of cryopreserved testicular sperm of northern pike (Esox lucius L.)

The effects of four different extenders and two sperm‐to‐egg ratios on fertilizing ability of cryopreserved testicular sperm of northern pike (Esox lucius L.) were tested in the present study. Testicular sperm was diluted with each of the four extenders (0.6 m sucrose + 15% DMSO, 0.3 m glucose + 15% DMSO, 0.6 m sucrose + 10% methanol and 0.3 m glucose + 10% methanol, all supplemented with 10% egg yolk and 1.7 g KCl L^?1) and frozen in 0.5‐ml straws at 2 cm above the surface of liquid nitrogen and thawed at 25°C for 30 s. Then 125 μl or 50 μl of frozen‐thawed testicular sperm was poured onto about 1250 eggs for fertilization. The results showed that both sperm‐to‐egg ratio and diluent had no significant influence on cryopreservation efficiency of testicular sperm, whereas cryoprotectant had a significant influence. The highest fertilization rate (92.2%) was obtained from testicular sperm cryopreserved in glucose‐based extender containing 10% methanol at a sperm‐to‐egg ratio of 1 × 10⁶ spermatozoa per egg. The results indicated that glucose‐based extender containing 10% methanol, 10% egg yolk and 1.7 g KCl L^?1 was a useful combination.     

The life cycle of Anguina agrostis: Embryogenesis

Bpird A. F. and Sptynes B. A. 1981. The life cycle of Anguina agrostis: embryogenesis. International Journal for Parasitology11: 23–33. Egg development, from laying to hatching, of two widely separated populations of Anguina agrostis, has been followed over a range of temperatures. Development rates for these two populations have been shown to be identical with a thermal optimum between 18 and 20°C. The minimum time recorded for embryogenesis through to hatching was 9–10 days.Embryogenesis was inhibited by temperatures of 27°C and above and hatching by temperatures greater than 23°C.No significant differences were detected in the dimensions of eggs from either population. These eggs have an average length of 95 μm and an average width of 38 μm.Electron microscope studies of sections through eggs undergoing synchronous development show that the first and apparently only moult of the larva in the egg commences about 7 days after the start of embryogenesis under optimal conditions. The sequence of morphological events that occur throughout embryogenesis are described and recorded for whole specimens observed at low resolution and the moulting sequence is described from high resolution electron micrographs of the cuticles of synchronously developing embryos and larvae.     

Effects of enzyme-treated soy protein on performance,digestive enzyme activity and mRNA expression of nutrient transporters of laying hens fed different nutrient density diets

It has been shown that enzyme-treated plant protein can increase performance and promote intestinal health, and save dietary protein. However, our understanding of the effects of enzyme-treated soy protein on performance and intestine function in laying hens, and its rational use, remains limited. The experiment was conducted to study the effect of enzyme-treated soy protein (ETSP) in different nutrient density diets on performance, egg quality, digestive enzyme activity and mRNA expression of amino acid transporters of laying hens. A total of 1 200 Lohmann laying hens (52 wk of age) was randomly divided into a 3 × 2 factorial design that included three nutrient levels: [positive control (PC), metabolisable energy (ME): 2 680 kcal/kg, CP: 15.5%; negative control 1 (NC1), ME: 2 630 kcal/kg, CP: 15%; negative control 2 (NC2), ME:2 580 kcal/kg, CP: 14.5%] and 2 ETSP levels (0 and 0.5%) for 12 weeks. Each treatment had 10 replicates with 20 birds. With the decrease of dietary nutrition density, egg production rate (P = 0.07) and feed conversion ratio (FCR) (P = 0.06) were reduced. Yolk colour was decreased, and yolk index was increased. Supplemented ETSP improved FCR (P = 0.05) and qualified egg rate (P < 0.05). The mass loss rate of egg was decreased after storage for 30 days (P < 0.05). An interaction between nutrient density and ETSP was observed on albumen height and Haugh unit (P < 0.05), and the effects were most noticeable in hens fed 0.5% ETSP in NC2 group. An increase in the activity of trypsin in duodenum (P < 0.05) and the relative expressions of jejunum peptide transporter 1 (PepT1) (P < 0.05) and B⁰ system neutral amino acid transport carrier (B⁰AT) mRNA (P < 0.01) was observed during ETSP supplementation. The nutrient density and ETSP supplementation had no significant effect on microbiota in the cecal contents. Overall, the results in this study indicated that the ME decreased 100 kcal/kg and CP decreased 1% in diet of laying hens had a decreasing trend on production performance, no effects on enzyme activity, amino acid transporter mRNA, and gut microbiota, whereas 0.5% ETSP can increase activity of trypsin, PepT1 and B⁰AT mRNA relative expressions, and improve FCR, qualified egg rate.     

Magnetic resonance studies of the anthranilate synthetase-phosphoribosyltransferase enzyme complex from Salmonella typhimurium.

The binding of Mn²⁺ to the anthranilate synthetase-phosphoribosyltransferase enzyme complex from Salmonella typhimurium was examined by electron paramagnetic resonance studies. Two types of binding sites were observed: one to two tight sites with a dissociation constant of 3–5 μm and five to six weaker sites with a dissociation constant of 40–70 μm. The activator constant for Mn²⁺ was found to be 9 μm for the glutamine-linked anthranilate synthetase activity and 4 μm for the phosphoribosyltransferase activity. These values are both in the range of the dissociation constant for the tight sites. Water proton relaxation rate measurements showed that the binary enhancement values for both classes of sites were equivalent, ?_b = 10.7 ± 2.0. The addition of chorismate to the Mn²⁺-enzyme complexes when predominantly the tight Mn²⁺ sites were occupied resulted in a large decrease in the observed enhancement (?_T = 2.0). Addition of 5-phosphoribosyl-1-pyrophosphate to the enzyme-Mn²⁺ complexes caused large decreases in the water proton relaxation rate (?_T = 1.5) when tight or tight plus weaker Mn²⁺ sites were occupied. No changes in the water proton relaxation rate were observed when glutamine, pyruvate, or anthranilate were added; a small decrease was observed when enzyme-Mn²⁺ was titrated with tryptophan. Tryptophan significantly altered the effect of the binding of chorismate but not of 5-phosphoribosyl-1-pyrophosphate. The effect of tryptophan on the water proton relaxation rate of a Mn²⁺-enzyme-chorismate complex using a variant enzyme complex which is tryptophan hypersensitive (P. D. Robison, and H. R. Levy, 1976, Biochim. Biophys. Acta. 445, 475–485) occurred at lower concentrations than for the normal enzyme complex. The uncomplexed anthranilate synthetase subunit was titrated with Mn²⁺ and found to have one to two binding sites with a dissociation constant of 300 ± 100 μm. This dissociation constant is much larger than the activator constant for Mn²⁺ for uncomplexed anthranilate synthetase which was determined to be 4 μm. These results indicate that the Mn²⁺-binding sites on anthranilate synthetase are altered when the enzyme complex is formed and that both chorismate and 5-phosphoribosyl-1-pyrophosphate interact closely with enzyme-bound Mn²⁺ or cause a large effect upon its environment.     

Analysis of phospholipase C (Bacillus cereus) action toward mixed micelles of phospholipid and surfactant.

The action of phospholipase C (Bacillus cereus) toward mixed micelles of phosphatidylcholine and the nonionic surfactant Triton X-100 is analyzed according to the “surfaceas-cofactor” kinetic scheme recently proposed for characterizing the action of lipolytic enzymes [Deems, R. A., Eaton, B. R., and Dennis, E. A. (1975) J. Biol. Chem.250, 9013–9020]. According to this scheme, the enzyme first associates with the surface or mixed micelles, where the dissociation constant is K_s^A. The enzyme, now part of the mixed micelle surface, then binds the substrate phospholipid molecule in its active site and this binding is related to the Michaelis constant, K_m^B. The surface, or mixed micelles in this scheme, behaves kinetically as a cofactor in that, under initial rate conditions, the surface properties of the mixed micelles are virtually unchanged after catalysis. For phospholipase C with egg phosphatidylcholine as substrate, it was found that at pH 6.4 (the pH optimum for the enzyme) and 40 °C, V is about 2 × 10³ μmol min^?1 (mg of protein)^?1. K_s^A is about 2 mm and K_m^B is 1 to 2 × 10^?10 mol cm^?2. The kinetic constants for phospholipase C are compared with those previously reported for phospholipase A₂ and the membrane-bound enzyme phosphatidylserine decarboxylase determined under similar conditions.     

Microencapsulation of bovine spermatozoa: effect of capsule membrane thickness on spermatozoal viability and fertility

This study was undertaken to investigate the relationship between the cationic polymer (poly-L-lysine) concentration and microcapsule membrane thickness, maintenance of spermatozoal motility in vitro, and pregnancy rate in 335 oestrous synchronized Friesian heifers. Semen was extended in CAPROGEN^™ containing 5% egg yolk and a final encapsulated spermatozoal concentration of 20 × 10⁶ spermatozoa ml⁻¹. Four concentrations of poly-L-lysine were studied (0.025, 0.05, 0.075, and 0. 1%, w/v). Microcapsule membrane thickness resulting from these concentrations was 3.22 ± 0.54 μm (mean ± SD), 5.30 ± 0.31 μm, 7.12 ± 0.41 μm, and 7.44 ± 0.85 μm, respectively (P < 0.05). Spermatozoal viability, as assessed by motility estimates at 24 h intervals during 120 h of incubation at 37°C, was not influenced by polymer concentration or different than unencapsulated controls. For fertility evaluation approximately 65 Friesian heifers were inseminated with spermatozoa either unencapsulated or encapsulated with one of the four polymer concentrations. Oestrous synchronization was accomplished with the combination of a progesterone-impregnated CIDR-B^® device containing a 10 mg oestradiol benzoate capsule inserted for 10 days with administration of 12.5 mg of prostaglandin F_2α on Day 6 of CIDR-B^® insertion. Heifers were inseminated in the uterine corpus at 24 h after CIDR-B^® removal which constituted the pro-oestrous stage of the cycle for 95.5% of the heifers. Inseminate dose rate was 5 × 10⁶ spermatozoa in 0.25 ml. Pregnancy rates were similar for heifers inseminated with encapsulated and unencapsulated spermatozoa (49.4 vs. 48.6%).From these studies we conclude that poly-L-lysine concentration does influence the microcapsule membrane thickness without affecting maintenance of spermatozoal motility in vitro or fertility of oestrous synchronised Friesian heifers.     

Efficient high-performance liquid chromatographic assay for the simultaneous determination of metoprolol and two main metabolites in human urine by solid-phase extraction and fluorescence detection

An improved, more efficient method for the determination of metoprolol and its two metabolites in human urine is reported. The simultaneous analysis of the zwitterionic metoprolol acidic metabolite (III, H117/04) with the basic metabolites α-hydroxymetoprolol (II, H119/66), metoprolol (I) and guanoxan (IV, internal standard) was achieved employing solid-phase extraction and isocratic reversed-phase HPLC. The analytes were extracted from urine (100 μl) using C₁₈ solid-phase extraction cartridges (100 mg), and eluted with aqueous acetic acid (0.1%, v/v)–methanol mixture (40:60, v/v, 1.2 ml). The eluents were concentrated (250 μl) under vacuum, and aliquots (100 μl) were analysed by HPLC with fluorescence detection at 229 nm (excitation) and 309 nm (emission) using simple isocratic reversed-phase HPLC (Novapak C₁₈ radial compression cartridge, 4 μm, 100×5 mm I.D.). Acetonitrile–methanol–TEA/phosphate buffer pH 3.0 (9:1:90, v/v) was employed as the eluent (1.4 ml/min). All components were fully resolved within 18 min, and the calibration curves for the individual analytes were linear (r²≥0.996) within the concentration range of 0.25–40.0 mg/ml. Recoveries for all four analytes were greater than 76% (n=4). The assay method was validated with intra-day and inter-day variations less than 2.5%.     

Chemical analysis of the female sex pheromone in Palpita nigropunctalis (Lepidoptera: Crambidae)

The lilac pyralid, Palpita nigropunctalis Bremer (Lepidoptera: Crambidae), is a common pest of Oleaceae plants. A crude extract of the female sex pheromone glands was examined by gas chromatography-electroantennogram detection (GC-EAD) and GC coupled to a mass spectrometer (GC/MS). The GC-EAD analysis revealed three EAG-active components (I–III) in a ratio of 1:0.2:0.01 (I: II: III). GC/MS analysis successfully recorded the mass spectra of I and II. For I, ions at m/z 238 (M⁺) and 220 ([M-18]⁺) indicated the structure of a monoenyl aldehyde with a 16-carbon chain. For II, M⁺ was not detected, but ions at m/z 222 ([M-60]⁺) and 61 ([AcOH+1]⁺) suggested that II was a monoenyl acetate with a 16-carbon chain. Further GC/MS analysis of the extract treated with dimethyl disulfide revealed that the double bonds in both I and II are located at the same position of 11th-carbon. In addition, the pheromone extract was examined by GC/Fourier transform-infrared spectrophotometer (GC/FT-IR). An IR spectrum of I showed characteristic absorption at 1716 and 966?cm^?1, indicating a formyl group and E configuration of the double bond, respectively. In the case of II, absorption at 1745 and 968?cm^?1 indicated an ester carbonyl and E configuration, respectively. Taken together and by comparison with authentic standards, I and II were confirmed as (E)-11-hexadecenal and (E)-11-hexadecenyl acetate, respectively; while III was speculated as (E)-11-hexadecen-1-ol. The synthetic I, II and III all coincided well with those of the natural components in chemical data, and elicited strong electroantennographic activity in male P. nigropunctalis.     

Novel salicylamide derivatives as potent multifunctional agents for the treatment of Alzheimer's disease: Design,synthesis and biological evaluation

A series of salicylamide derivatives were designed, synthesized and evaluated as multifunctional agents for the treatment of Alzheimer’s disease. In vitro assays demonstrated that most of the derivatives were selective AChE inhibitors. They showed good inhibitory activities of self- and Cu²⁺-induced Aβ_1–42 aggregation, and significant antioxidant activities. Among them, compound 15b exhibited good inhibitory activity toward RatAChE and EeAChE with IC₅₀ value of 10.4 μM and 15.2 μM, respectively. Moreover, 15b displayed high antioxidant activity (2.46 Trolox equivalents), good self- and Cu²⁺-induced Aβ_1–42 aggregation inhibitory potency (42.5% and 31.4% at 25.0 μM, respectively) and moderate disaggregation ability to self- and Cu²⁺-induced Aβ_1–42 aggregation fibrils (23.4% and 27.0% at 25 μM, respectively). Furthermore, 15b also showed biometal chelating abilities, anti-neuroinflammatory ability and BBB permeability. These multifunctional properties indicated compound 15b was worthy of being chosen for further pharmacokinetics, toxicity and behavioral researches to test its potential for AD treatment.     

Daily energy expenditure and water turnover in two breeds of laying hens kept in floor housing

Laying hens are increasingly kept in barn or free-range systems, which not only allows birds to move freely but also potentially entails higher energy expenditures due to higher locomotor activity. Therefore, the aim of our study was to quantify the daily energy expenditure (DEE) and water turnover in freely moving laying hens. For that purpose, 10 Lohmann Selected Leghorn (LSL) and 10 Lohmann Brown (LB) hens were obtained from a conventional breeding company at 17 weeks of age. The trial started when birds reached an age of 34 weeks. All 20 birds were kept together in the same littered floor pen (12.1 m²). The pen was equipped with perches, a nest box, feeding and nipple drinkers. The DEE was determined individually for all experimental birds (n = 20) for a total of nine days using the doubly labelled water (DLW) method. Lohmann Brown hens were heavier than LSL hens, but laying rate did not differ between the two breeds, that is, one egg per hen and day during the study period. Average egg mass was 63.1 ± 0.20 g in LB and 61.7 ± 0.12 g in LSL hens, which converted to an egg energy content of 420 and 410 kJ/egg, respectively. Dilution spaces for oxygen and hydrogen differed between the breeds but not the respective turnover rates. Total body water as a percentage of body mass (LB: 54.4%, LSL: 53.8%; SEM = 0.7, F_1,18 = 0.41, P = 0.513) and total water intake (TWI) per day (LB: 275 ml/day, LSL: 276 ml/day; SEM = 20, F_1,17 = 0, P = 0.994) did not differ between LB and LSL hens. Individual DEE increased with body mass in LB but not in LSL hens. Average DEE did not differ between the two breeds (LB: 1 501 kJ/day; LSL: 1 520 kJ/day; SEM = 32.1, F_1,17 = 2.54, P = 0.131). However, when comparing the DEE on a metabolic mass basis, LSL hens expended with 984 kJ/kg^0.75 on average significantly more energy per day than LB hens (895 kJ/kg^0.75; SEM = 20.3, F_1,18 = 10.1, P = 0.005). Our results suggest that the DLW technique is a viable method to measure the energy expenditure and water turnover over several days in laying hens. Furthermore, we show that laying hens kept in floor pens fit into the general pattern of DEE among wild birds.     

Conformations of the d-glucarolactones and d-glucaric acid in solution

The conformations of d-glucaric acid (1), d-glucaro-1,4-lactone (2), d-glucaro-6,3-lactone (3), and d-glucaro-1,4:6,3-dilactone (4) in solution were investigated by ¹H-n.m.r. and ¹³C-p.F.t., n.m.r. spectroscopy. The solvents used were deuterium oxide, methanol-d₄, and dimethyl sulfoxide-d₆, and praseodymium chloride was employed as a lanthanide shift-reagent. For 2, it was found that the conformational equilibrium ³E(d)

E₃(d) exists in solution, and that the OH-5 group tends to occupy the position over the lactone ring in the favored E₃(d),gg conformation. The n.m.r. data for 3 indicated that the conformational equilibrium is shifted in favor of the ⁴E(d)

E₄(d),gt conformation in solution. The dienvelope conformation ³E:E₄(d) was found to be the favored conformation of 4. For 1, a conformational equilibrium between one planar, zigzag form and two sickle forms was indicated by the n.m.r. data observed. ¹³C-N.m.r. spectroscopy proved to be a convenient method for monitoring the lactonization of 1, and the hydrolysis of its lactones. Lactones other than 2–4 were not found in solutions prepared from 1–4, either during their mutarotation or after equilibration at 30°.