Biosynthesis, secretion and in vivo isotopic labelling of venom of the Egyptian cobra, Naja haje annulifera.

The venom glands of Elapidae differ from those of the Viperidae by lacking an expanded central lumen; the venom is stored in the tubular lumina as well as inside the cells in densely packed secretion granules. Using isotope tracer techniques, it was found that in the Egyptian cobra (Naja haje annulifera) venom is secreted both from pre-existing and from newly-formed granules. The rate of protein biosynthesis peaks at 4-9 days after venom was extracted (milked) from the glands. Highly labelled toxins (1-10 mCi/mmole protein) were isolated in good yield from the venom of snakes chronically intubated and infused i.p. with (3H)-amino acids. Repeated Fluothane (Halothane) anaesthesias and venom collections had no ill effect on venom yield. The radioactive venom and its component toxins retained full biological potency.

Ploidy, ascus formation and recombination in Torulaspora (Debaryomyces) hansenii.

X-ray inactivation studies on the type strain of Torulaspora hansenii carried out to determine ploidy, provided proof that the species has a haplontic life cycle, a fact which hitherto has only been presumed. Observations on the genesis of the ascus by light microscopy and transmission electron microscopy provide no evidence for, what some earlier workers in this field have presumed to be, heterogamous conjugation between a mother cell and its bud. They do, however, show that asci, bearing obliquely-attached, vestigal, bud-like appendages, arise from some cells to form single, non-abstricting, and frequently, recurving protuberances which enlarge. These could, conceivably, be responsible for the impression that abstricted buds are connected to the mother-cells by bent copulatory tubes. The formation during sporulation of elongated protuberances and the presence of a medial, electron-dense line within the electron-translucent layer of the walls of ascospores fixed with OsO4 preclude the possibility of using these features to differentiate between the genera Torulaspora and Debaryomyces. Furthermore, recombinant studies, which involved the use of auxotrophic mutants, indicated that during sporulation the fusion of independent cells accounted for only 0.03-0.6% of the asci formed. The conclusion was reached that somatogamous autogamy must be the main agency of diploidization and that the species is largely inbreeding.

The ultrastructure of the human epidermis following ultracentrifugation.

Ultracentrifugation of the human epidermis was undertaken to uncover the forces responsible for the establishment and maintenance of the supranuclear melanin cap in basal cells. The wide spacing and elasticity of the tonofibrils caused a selective trapping of melanosomes in this region. At the same time the experiments produced pictures resembling dedifferentiation of the plasma membrane as in the fetal state, and differentiation of the tonofibrillar mass resembling the granular and horny layers. Once the tonofibrils had retracted and massed together, the order of intracellular sedimentation was: melanosome, chromatin, mitochondrion, tonofibril and ribosome.