Rescue of adeno-associated virus from recombinant plasmids: gene correction within the terminal repeats of AAV

We have isolated three types of pBR322-AAV recombinant plasmids that contain deletions within the 145 bp AAV terminal repeats. When the plasmids were transfected into human cells, mutants that contained deletions within the left (type I) or right (type II) terminal repeat were viable. Of four mutants examined that contained deletions in both termini (type III), only one was viable. All of the viable mutants produced AAV virions that contained wild-type AAV DNA. Furthermore, the viable type III deletion could be converted to a nonviable mutant by deleting all copies of an 11 bp sequence from its termini. We conclude that there is an efficient mechanism for correcting deletions within the AAV termini. A model that could account for these observations is also discussed.     

Laser microdissection of actinomycin D segregated nucleoli

Nucleoli of tissue culture cells were segregated into their fibrillar (light) and granular (dark) components by treatment with actinomycin D. Following this segregation, the cells were treated with quinacrine hydrochloride, an agent which selectively sensitizes the nucleoli to argon laser light. The actinomycin D-segregated, quinacrine-sensitized nucleolar components (dark and light) were selectively irradiated with the laser microbeam and subsequent uridine uptake assayed. The data indicate that selective damage to the light (fibrillar) area is generally more damaging than damage to the dark (granular) area. These results support the idea that DNA is closely associated with the nucleolar fibrillar component.     

Separation of a New Deoxyribonucleic Acid Polymerase from Vaccinia-infected HeLa Cells

HeLa cell deoxyribonucleic acid (DNA) polymerase was purified about 100-fold by sequential column chromatography on phosphocellulose, hydroxylapatite, and Bio Rex 70. A new form of DNA polymerase found in vaccinia virus-infected cells was separated from HeLa DNA polymerase by chromatography on diethylamino-ethyl cellulose. The new form was also purified approximately 100-fold in the same manner as the HeLa DNA polymerase. In addition to chromatographic differences, the two enzymes differed with regard to primer response, relative activity at high pH, inactivation by heat and p-chloromercuribenzoate, and inhibition by vaccinia antiserum.     

Neue oder wenig bekannte Flechten in der Tschechoslowakei. I

Es werden 28 Arten von lichenisierten Fungi (Flechten) mit kritischen taxonomischen Hinweisen oder Ergänzungen zu den in der Literatur vorhandenen Beschreibungen, oft mit chorologischen Bemerkungen und Angaben über die ökologischen Verhältnisse ihrer Standorte angeführt, von denen die nachgenannten Arten und Namenskombinationen neu sind:Verrucaria scabra Vězda sp. n.,Geisleria xylophila Vězda sp. n.,Toninia steineri Poelt etVězda sp. n.,Pachyascus byssaceus (Vězda) Vězda comb. n. undMicarea gomphillacea (Nyl.) Vězda comb. n.     

Inhibition of nitrite assimilation by uncouplers of phosphorylation

Summary Carbonyl cyanide m-chlorophenylhydrazone (CCCP) and pentachlorophenol (PCP), two powerful uncouplers of phosphorylation, specifically inhibit the assimilation of nitrite in the course of nitrate reduction. These results support our former conclusion that high-energy phosphate is involved in the metabolism of nitrite.