Absolute configurations of isoflavans

The absolute configurations of isoflavans and isoflavanquinones isolated from Cyclolobium, Dalbergia and Machaerium species were established by comparison of their ORD curves with that of (3S)-5,7,3′,4′-tetra-methoxyisoflavan and (3S)-7,4′-dimethoxyisoflavan-2′,5′-quinone, respectively. The assignments were checked by the ozonolysis of the isoflavan (?)-duartin to (R)-paraconic acid and the oxidation of isoflavans to isoflavanquinones. The PMR spectra of the dihydropyran ring of the isoflavans are discussed in terms of the preferred conformation of this ring.     

A detailed serological analysis of a xenogeneic anti-Ia serum

Rabbit anti-mouse-Ia serum was raised against Ia specificities present in CBAJH (H-2 _k) serum. This xenogeneic antiserum was considered to react with similar specificities to those detected by mouse anti-Ia^k alloantisera and more evidence is now presented for this contention. By absorption, the xenogeneic antiserum was found to react with spleen, lymph node, bone marrow, and thymus, reactions similar to that found with the allogeneic anti-Ia^k antiserum. Furthermore, red cells, platelets, brain, kidney, and liver could not absorb the activity from the xenogeneic antiserum, demonstrating the selective tissue distribution of the antigens reactive with this serum. This reactive population was previously shown to consist of B cells and a subpopulation of T cells. In a backcross study of (C57BL/6 × A)F₁ × C57BL/6, the rabbit anti-Ia and mouse anti-Ia reactions were found to segregate together, and some evidence for the genetic regulation of the expression of Ia specificities was also found. By direct testing, and by absorption testing using a number of strains, the xenogeneic antiserum was shown to contain high titers of antibody to Ia.1, 3, 7, 15, and 17; lower titers to Ia.19, and 22; little antibody to Ia.18, and no reaction for the private specificity Ia. 2, although the multiple absorptions required to define these specificities may have observed some reactions. The data indicate that the xenogeneic and allogeneic anti-Ia_k antisera recognize similar Ia determinants, which map to theLA, IE andIC subregions of theH-2 complex. These have been given the same specificity designation as the allogeneic specificities, but they are separately identified by a prime (').     

The fertilizing capacity of ram testicular spermatozoa,freshly collected and after storage in cauda epididymal fluid

Epididymal fluid may contain substances which promote development of the fertilizing capacity of testicular spermatozoa under in vitro conditions, provided that the spermatozoa are exposed to such substances for long periods of time. In an attempt to resolve this question, the fertilizing capacity of testicular spermatozoa was assessed before and after storage in cauda epididymal fluid and comparisons made with ejaculated spermatozoa from the same rams. Of the 13 eggs examined from the group of ewes inseminated with ejaculated spermatozoa 61.5% were found to be in the 2-to 8-cell stage. No fertilized eggs were recovered from ewes impregnated with freshly collected testicular spermatozoa. Nor were any cleaved eggs obtained from the group of ewes inseminated with testicular spermatozoa stored in cauda epididymal fluid at 4°C for 7 to 11 days. We suggest there-fore, that in order to develop maximal fertilizing capacity, mammalian spermatozoa must be exposed to specific concentrated testicular and epididymal secretions in a sequential order and within strict time limits.     

Some pharmacological properties of neuromuscular transmission in the oviduct of the locust,Locusta migratoria

The effects of various pharmacological agents on neurally evoked contractions of the visceral muscles of the oviduct of Locusta migratoria have been examined. The pentapeptide, proctolin, at low concentrations (10^?11 M?10^?10 M), induced an increase in the amplitude of neurally evoked contractions and basal tonus, and induced the appearance and increased the frequency of myogenic contractions. Glutamate, at 10^?4 M, produced a small transient contraction which in some preparations was accompanied by a reduction in amplitude of neurally evoked contractions. Octopamine, at 10^?6 M, reduced the amplitude of neurally evoked contractions and also resulted in a relaxation of the muscles. The octopaminergic effects were inhibited by the α-aminergic antagonist phentolamine. Neurally evoked contractions were unaffected by dopamine, 5-HT or the acetylcholine receptor antagonists atropine and hexamethonium. Acetylcholine increased the amplitude of neurally evoked contractions, but only at the high concentration of 10^?3 M. The possible role of proctolin and glutamate as excitatory neuro-transmitters and the inhibitory action of octopamine is discussed.     

Differences in the distribution of O-sulphate groups of cell-surface and secreted heparan sulphate produced by human neuroblastoma cells in culture

Confluent cultures of a human neuroblastoma cell line (CHP100) were incubated for 48 h with d-[1-³H]glucosamine and sodium [³⁵S]sulphate. Radioactive glycosaminoglycans were analysed in the growth medium, rapid trypsin digest of the cell monolayer and a 1% (w/v) Triton/0.5 M NaOH extract of the final cell pellet. Sulphated glycosaminoglycans co-chromatographed when eluted by NaCL gradient from DEAE-cellulose. The medium contained mainly chondroitin sulphates, whereas the cell surface was enriched in heparan sulphate. Heparan sulphate was isolated as chondroitinase ABC-resistant material and treated with nitrous acid. Analysis of the scission products on Bio-Gel P-10 yielded fragments varying in size from single disaccharides to glycans consisting of nine disaccharide units. Cell-surface and medium heparan sulphate had respectively 52% and 54% N-sulphated glucosamine residues distributed in similar patterns along the polymer chain. The N:O-sulphate ratio of neuroblastoma heparan sulphate was 1.1:1. Analysis by high-voltage electrophoresis of di- and tetrasaccharide products produced by nitrous acid treatment showed that the distribution of $\text{‘O’-}\text{sulphate}$ groups differed strikingly between heparan sulphates from the medium and cell-surface compartments. A di-O-sulphated tetrasaccharide was identified in both heparan sulphate species. The absence of detectable amounts of ³⁵[S]sulphate associated with fragments larger than tetrasaccharide supports the close topographical association of N-sulphate and O-sulphate groups.     

Effects of Monovalent and Divalent Cations on 3-(+)[125I]Iododizocilpine Binding to the N-Methyl-d-Aspartate Receptor of Rat Brain Membranes

We have investigated the binding of 3-[125I]iododizocilpine ([125I]iodo-MK-801) to the N-methyl-D-aspartate (NMDA) receptor in well-washed rat brain membranes. [125I]Iododizocipline binding was displaced by the following: dizocilpine greater than thienylphencyclidine greater than phencyclidine greater than ketamine. Binding of [125I]iododizocilpine was enhanced by glutamate, glycine, and spermidine, whose actions could be reversed by CGS-19755, 7-chlorokynurenate, and arcaine, respectively. [125I]Iododizocilpine binding was also enhanced by a number of divalent cations, including Ba2+, Ca2+, Mg2+, Mn2+, and Sr2+, and several monovalent cations, including Na+ and K+. These cations enhanced [125I]iododizocilpine binding by an action at the polyamine site. In addition, the inhibitory effects associated with high concentrations of these cations was markedly reduced compared to those found in previous studies with [3H]dizocilpine. Analysis of the ability of spermidine, Mg2+, and Sr2+ to alter the inhibition of [125I]iododizocilpine by arcaine gave pA2 values of 5.41, 4.47, and 4.93, corresponding to EC50 concentrations of 3.9, 34.7, and 12.0 microM, respectively, suggesting that physiological concentrations of Mg2+ may occupy the polyamine site. These results demonstrate that [125I]iododizocilpine is a useful probe for the NMDA receptor. Moreover, its high specific activity and relative insensitivity to the inhibitory actions of divalent cations should make [125I]iododizocilpine a valuable ligand for the study of NMDA receptors in intact cellular systems.     

Proteolytic degradation of heterologous proteins expressed inAspergillus niger

Summary Proteolytic degradation of heterologous proteins expressed in the filamentous fungusAspergillus niger reduces the yield of authentic target protein. The activities ofA. niger proteases are differentiated by their effects on two proteins expressed and secreted fromA. niger: hen egg-white lysozyme and porcine pancreatic phospholipase A₂.     

Empruthotrema dasyatidis n. sp. (Monogenea: Monocotylidae) from the olfactory sacs of Dasyatis fluviorum (Rajiformes: Dasyatidae) from Moreton Bay,Queensland

The monocotylid monogenean Empruthotrema dasyatidis n. sp. is reported from the olfactory sacs of the brown stingray, Dasyatis fluviorum Ogilby, 1908, from Moreton Bay, Queensland, Australia. This is the first record of Empruthotrema from the family Dasyatidae. E. dasyatidis n. sp. differs from other species of Empruthotrema by possessing eye pigment, which may be scattered, and by its small size. The generic diagnosis for Empruthotrema is amended.     

Promoter methylation and progressive transgene inactivation inArabidopsis

Agrobacterium-transformedArabidopsis plants were generated and the stability of their T-DNA-encoded resistance to kanamycin was examined. Of seven families, each homozygous for a single insertion event, two showed progressive inactivation of resistance over four generations of inbreeding. Loss of resistance was associated with methylation of anSst II site in thenos promoter of the kanamycin resistance gene. Treatment of plant roots from inactive lines with the demethylating agent 5-azacytidine restored the ability of such lines to form callus on kanamycin-containing media. These observations are consistent with the view that methylation is a factor in the progressive inactivation of transgenes inArabidopsis.