PATENT ABSTRACTS

which participate in the composition of this recombinant DNA, in particular the thymine groups, being replaced by 5-bromouracil groups. The invention also relates to a method for manu- facturing this probe, this method comprising the culturing of cell hosts, more especially E. coli, which are auxotrophic for thymine in a medium containing a limiting concentration of thymine and containing 5-bromouracil. After the re- quisite incubation time, the supernatant is removed and the probe is recovered from the bacterial cells.

4980285

M E T H O D F O R P R O D U C I N G L - A M I N O A C I D S

Konosuke Sano, Chieko Osumi, Kazuhiko Mat- sui, Kiyoshi Miwa, Tokyo, Japan assigned to Ajinomoto Co Inc

A method for producing an L-amino acid, which comprises inserting a gene which codes for an en- zyme which is utilized on the route of bio- synthesis of an L-amino acid product into one of at least two plasmid vectors which have com- patible replicating origins different from each other, inserting a second gene which codes for an enzyme different from the first enzyme on the route of biosynthesis of the L-amino acid into a second of the plasmid vectors; introducing the thus obtained recombinant plasmids into a strain of Coryneform bacteria; and culturing the thus transformed strain which is capable of pro- ducing the L-amino acid, said two enzymes being highly rate determining enzymes for the bio- synthesis of L-amino acid.

4980286

I N V I V O I N T R O D U C T I O N A N D E X P R E S S I O N O F F O R E I G N

G E N E T I C M A T E R I A L I N E P I T H E L I A L C E L L S

Jeffrey R Morgan, Richard C Mulligan assigned to Whitehead Institute for Biomedical Research

Epithelial cells expressing foreign genetic material are described. The foreign genetic material can be DNA or RNA which does not occur in epithelial cells; DNA or RNA which oc- curs in epithelial cells but is not expressed in them at levels which are biologically significant; DNA or RNA which occurs in epithelial and has been modified so that it is expressed in epithelial

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cells; and any DNA or RNA which can be modified to be expressed in epithelial cells, alone or in any combination thereof. In addition, epi- thelial ceils of the present invention can express genetic material encoding a selectable marker by which cells expressing the foreign genetic material can be expressed.

4980288

S U B T I L I S I N W I T H I N C R E A S E D T H E R M A L S T A B I L I T Y

Philip Bryan, Michele L Rollence, Michael W Pantoliano assigned to Genex Corporation

Cloned DNA is mutated by creating a single- stranded target region in a cloned DNA seg- ment, and introducing a mutation into the single-stranded target region by treating the tar- get region with a chemical or biological mutagenizing agent capable of introducing mutations into single-stranded DNA. The mutated target region then is rendered double- stranded and a microorganism is transformed with the mutated double-stranded DNA present in an expression vector. The transformed micro- organism is cultivated under conditions wherein the mutated DNA is expressed to form an ex- pression product, and the expression product is screened to identify a desired mutation in the DNA segment. Mutant subtilisins of enhanced thermal stability are also disclosed.

4980289

P R O M O T E R D E F I C I E N T R E T R O V I R A L V E C T O R

Howard M Temin, Joseph Dougherty assigned to Wisconsin Alumni Research Foundation

A recombinant retrovirus vector is disclosed. It is of the type having a normally replication in- competent retrovirus gene sequence with a fore- ign eukaryotic gene to be expressed. The retrovirus gene sequence is designed so as to be promoter deficient in the right side LTR. The vector can produce progeny virus from helper cells, which progeny can infect a eukaryotic host cell, form a provirus, and express the eukaryotic gene in the host cell. However, the provirus will then be defective in the retrovirus promoter, such that retrovirus RNA is not expressed from the provirus.