Copper ions and hydrogen peroxide form hypochlorite from NaCl thereby mimicking myeloperoxidase

Sea urchins have elaborated multiple defenses to assure monospermic fertilization. In this work, we have concentrated on a study of the mechanism(s) by which hydrogen peroxide (H₂O₂) prevents polyspermy in Arbacia punctulata. We found that it is not H₂O₂ but probably hypochlorous acid/hypochlorite (HOCl/OCl^?) derived from H₂O₂ that is toxic to the supernumerary sperm. The spermicidal activity of H₂O₂ is potentiated by at least one order of magnitude by cupric ions (Cu²⁺). This increased toxicity is not due to the formation of hydroxyl radicals (·OH) because ·OH scavengers did not counteract the activity of Cu²⁺. More-over, substitution of Cu²⁺ by ferrous ions (Fe²⁺), which are known to cause formation of ·OH from H₂O₂, had no effect on fertilization even at 10²?10³ times higher concentrations. In contrast, 3-amino-1,2,4-triazole (AT), an HOCl/OCl^? scavenger, totally reversed the toxic effects of Cu²⁺. Furthermore, we found that HOCl/OCl^? is generated in solutions of H₂O₂ and Cu²⁺ in the presence of 0.5 M NaCl and that its accumulation is abolished by AT. Thus it is possible that the antifertility properties of copper are due to its ability to mediate formation of HOCl/OCl^?. HOCl/OCl^? generated by Cu²⁺ from H₂O₂ and Cl^?, a low concentration of exogenously added HOCl/OCl^?, or increased concentrations of H₂O₂ has similar inhibitory effects on the fertilization process in sea urchins. Therefore, we suggest that polyspermy is prevented by the action of a myeloperoxidase that affects the formation of HOCl/OCl^? from the Cl^? present in sea water through reaction with H₂O₂ generated by the newly fertilized egg.     

Neem (Azadirachta indica) cultivated in Haiti

So that valuable products from the neem tree (Azadirachta indica) will be readily available in the future, countries in the neotropics should emulate Haiti and grow the species where it thrives even in eroded, semiarid, depauperate areas suitable for few other trees.     

Recognition sites for a membrane-derived DNA binding protein preparation in the E. coli replication origin

Summary The DNA binding protein B' preparation, isolated from the membrane of E. coli, recognizes two sites, one of which is locatd in the minimum oriC (35–270 bp) and the other between base pairs 417 and 488. Recognition is only possible when restriction fragments containing these sites are in single-stranded state. At the first site the strand reading 3OH-5P in the direction of the E. coli genetic map is recognized, at the second site the 5P-3OH strand.     

Determination of Some Molecular Parameters of Tyrosine Hydroxylase From Rat Adrenal, Rat Striatum, and Human Pheochromocytoma

The molecular parameters of tyrosine hydroxylase (EC 1.14.16.2) from rat adrenal, rat striatum, and human pheochromocytoma were determined by combined gel filtration and sucrose gradient ultracentrifugation. The enzyme from rat adrenal has a calculated molecular weight of 228,000, a Stokes radius of 60.9 A, a sedimentation coefficient of 9.10S, and a frictional ratio of 1.39. The enzyme from rat striatum has a calculated molecular weight of 210,000, a Stokes radius of 54.3 A, a sedimentation coefficient of 9.38S, and a frictional ratio of 1.28. Tyrosine hydroxylase from human pheochromocytoma tissue has a calculated molecular weight of 255,000, a Stokes radius of 68.2 A, a sedimentation coefficient of 9.08S, and a frictional ratio of 1.50. These results indicate that the tyrosine hydroxylases from central and peripheral tissue in the rat are quite similar although the human enzyme appears to be significantly larger.     

THE POLLINATION DYNAMICS OF SYMPATRIC SPECIES OF PEDICULARIS (SCROPHULARIACEAE)

Sympatric populations of Pedicularis oederi, P. cystopteridifolia, and P. groenlandica on the Beartooth Plateau (Montana) were obligately dependent on Bombus pollinators. Their corolla colors were mutually distinct to insect vision, but their nectars had identical sugar components. Analysis of corbicular pollen loads of pollinating insects indicated a high degree of polylecty. Queen/worker ratios of pollinators on plant species corresponded to the parallel phenological sequences of plant blooming and insect caste development. The total number of individual pollinators of each Bombus species on all plants was directly related to the number of plant species it pollinated, but a comparable relationship between the number of pollinators on a plant species to the number of Bombus species pollinating it was not found. Morphological and behavioral correspondence of floral mechanisms and pollinators form an integral part of the general pattern of coadaptive evolution of the floral ecology of Pedicularis in North America known from previous studies. Reproductive isolation between Pedicularis species in this study is attributed to internal barriers. Wide overlaps of blooming seasons, proboscis lengths of bumblebee species and castes, and pollinator species on Pedicularis species suggest resource sharing, rather than resource partitioning or competition for resources among plant and insect species and individuals.     

Clostridium perfringens: I. Sporulation in a Biphasic Glucose-Ion-Exchange Resin Medium

A biphasic culture medium suitable for cultivation and sporulation of Clostridium perfringens, C. botulinum, and C. sporogenes was devised. The medium designed for use in a disposable, compartmented, plastic film container contained peptones, yeast extract, minerals, an anion exchange resin, and glucose in 4% agar as the solid phase and (NH(4))(2)SO(4) and 0.1% agar as the liquid phase. With the biphasic system, it was not necessary to use active cultures as inocula. Growth was at least equal to that obtained in conventional media, and spore production of 9 out of 12 strains of C. perfringens equalled or usually exceeded that of conventional media.     

Interpretation of Diffusion Susceptibility Data Obtained with 50-μg Carbenicillin Discs Against Gram-Negative Organisms

A total of 284 clinical isolates of various species of Enterobacteriaceae, Pseudomonas aeruginosa, P. maltophilia, and Acinetobacter anitratum were tested for susceptibility to carbenicillin by the standardized Bauer-Kirby disc diffusion technique and a microtiter broth dilution method. The data obtained led to the following proposed criteria for the interpretation of the results of disc susceptibility tests. Enterobacteriaceae that yield zones of inhibition equal to or greater than 20 mm in diameter around 50-mug discs of carbenicillin are designated as sensitive to the drug; isolates that yield zones measuring from 18 to 19 mm in diameter are reported as of equivocal (intermediate) susceptibility to the drug, whereas those enterobacterial isolates that are characterized by zones of inhibition of 17 mm or less in diameter are interpreted as resistant to carbenicillin. Isolates of P. aeruginosa, P. maltophilia, and A. anitratum yielding zones of 14 mm or more in diameter around 50-mug discs of carbenicillin are reported as sensitive, whereas those isolates that are characterized by zones of 13 mm or less in diameter are reported as resistant to this drug.