Open Access. Powered by Scholars. Published by Universities.®

Medical Biochemistry Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 23 of 23

Full-Text Articles in Medical Biochemistry

Rho Activation Of Mdia Formins Is Modulated By An Interaction With Inverted Formin 2 (Inf2), Hua Sun, Johannes S. Schlondorff, Elizabeth J. Brown, Henry N. Higgs, Martin R. Pollak Feb 2011

Rho Activation Of Mdia Formins Is Modulated By An Interaction With Inverted Formin 2 (Inf2), Hua Sun, Johannes S. Schlondorff, Elizabeth J. Brown, Henry N. Higgs, Martin R. Pollak

Dartmouth Scholarship

Inverted formin 2 (INF2) encodes a member of the diaphanous subfamily of formin proteins. Mutations in INF2 cause human kidney disease characterized by focal and segmental glomerulosclerosis. Disease-causing mutations occur only in the diaphanous inhibitory domain (DID), suggesting specific roles for this domain in the pathogenesis of disease. In a yeast two-hybrid screen, we identified the diaphanous autoregulatory domains (DADs) of the mammalian diaphanous-related formins (mDias) mDia1, mDia2, and mDia 3 as INF2_DID-interacting partners. The mDias are Rho family effectors that regulate actin dynamics. We confirmed in vitro INF2_DID/mDia_DAD binding by biochemical assays, confirmed the in vivo interaction of these …


Proliferation Of Aneuploid Human Cells Is Limited By A P53-Dependent Mechanism, Sarah L. Thompson, Duane A. Compton Jan 2010

Proliferation Of Aneuploid Human Cells Is Limited By A P53-Dependent Mechanism, Sarah L. Thompson, Duane A. Compton

Dartmouth Scholarship

Most solid tumors are aneuploid, and it has been proposed that aneuploidy is the consequence of an elevated rate of chromosome missegregation in a process called chromosomal instability (CIN). However, the relationship of aneuploidy and CIN is unclear because the proliferation of cultured diploid cells is compromised by chromosome missegregation. The mechanism for this intolerance of nondiploid genomes is unknown. In this study, we show that in otherwise diploid human cells, chromosome missegregation causes a cell cycle delay with nuclear accumulation of the tumor suppressor p53 and the cyclin kinase inhibitor p21. Deletion of the p53 gene permits the accumulation …


A Developmental Cycle Masks Output From The Circadian Oscillator Under Conditions Of Choline Deficiency In Neurospora, Mi Shi, Luis F. Larrondo, Jennifer J. Loros, Jay C. Dunlap Dec 2007

A Developmental Cycle Masks Output From The Circadian Oscillator Under Conditions Of Choline Deficiency In Neurospora, Mi Shi, Luis F. Larrondo, Jennifer J. Loros, Jay C. Dunlap

Dartmouth Scholarship

In Neurospora, metabolic oscillators coexist with the circadian transcriptional/translational feedback loop governed by the FRQ (Frequency) and WC (White Collar) proteins. One of these, a choline deficiency oscillator (CDO) observed in chol-1 mutants grown under choline starvation, drives an uncompensated long-period developmental cycle ( approximately 60-120 h). To assess possible contributions of this metabolic oscillator to the circadian system, molecular and physiological rhythms were followed in liquid culture under choline starvation, but these only confirmed that an oscillator with a normal circadian period length can run under choline starvation. This finding suggested that long-period developmental cycles elicited by nutritional stress …


Nicotinamide Riboside Kinase Structures Reveal New Pathways To Nad+, Wolfram Tempel, Wael M. Rabeh, Katrina L. Bogan, Peter Belenky, Marzena Wojcik, Heather F. Seidle, Lyudmila Nedyalkova, Tianle Yang, Anthony A. Sauve, Hee-Won Park, Charles Brenner Oct 2007

Nicotinamide Riboside Kinase Structures Reveal New Pathways To Nad+, Wolfram Tempel, Wael M. Rabeh, Katrina L. Bogan, Peter Belenky, Marzena Wojcik, Heather F. Seidle, Lyudmila Nedyalkova, Tianle Yang, Anthony A. Sauve, Hee-Won Park, Charles Brenner

Dartmouth Scholarship

The eukaryotic nicotinamide riboside kinase (Nrk) pathway, which is induced in response to nerve damage and promotes replicative life span in yeast, converts nicotinamide riboside to nicotinamide adenine dinucleotide (NAD+) by phosphorylation and adenylylation. Crystal structures of human Nrk1 bound to nucleoside and nucleotide substrates and products revealed an enzyme structurally similar to Rossmann fold metabolite kinases and allowed the identification of active site residues, which were shown to be essential for human Nrk1 and Nrk2 activity in vivo. Although the structures account for the 500-fold discrimination between nicotinamide riboside and pyrimidine nucleosides, no enzyme feature was identified to recognize …


P53 Activation By Knockdown Technologies, Mara E. Robu, Jon D. Larson, Aidas Nasevicius, Soraya Beiraghi, Charles Brenner May 2007

P53 Activation By Knockdown Technologies, Mara E. Robu, Jon D. Larson, Aidas Nasevicius, Soraya Beiraghi, Charles Brenner

Dartmouth Scholarship

Morpholino phosphorodiamidate antisense oligonucleotides (MOs) and short interfering RNAs (siRNAs) are commonly used platforms to study gene function by sequence-specific knockdown. Both technologies, however, can elicit undesirable off-target effects. We have used several model genes to study these effects in detail in the zebrafish, Danio rerio. Using the zebrafish embryo as a template, correct and mistargeting effects are readily discernible through direct comparison of MO-injected animals with well-studied mutants. We show here indistinguishable off-targeting effects for both maternal and zygotic mRNAs and for both translational and splice-site targeting MOs. The major off-targeting effect is mediated through p53 activation, as detected …


Circadian Rhythmicity By Autocatalysis, Arun Mehra, Christian I. Hong, Mi Shi, Jennifer J. Loros, Jay C. Dunlap, Peter Ruoff Jul 2006

Circadian Rhythmicity By Autocatalysis, Arun Mehra, Christian I. Hong, Mi Shi, Jennifer J. Loros, Jay C. Dunlap, Peter Ruoff

Dartmouth Scholarship

The temperature compensated in vitro oscillation of cyanobacterial KaiC phosphorylation, the first example of a thermodynamically closed system showing circadian rhythmicity, only involves the three Kai proteins (KaiA, KaiB, and KaiC) and ATP. In this paper, we describe a model in which the KaiA- and KaiB-assisted autocatalytic phosphorylation and dephosphorylation of KaiC are the source for circadian rhythmicity. This model, based upon autocatalysis instead of transcription-translation negative feedback, shows temperature-compensated circadian limit-cycle oscillations with KaiC phosphorylation profiles and has period lengths and rate constant values that are consistent with experimental observations.


The Caenorhabditis Elegans Heterochronic Regulator Lin-14 Is A Novel Transcription Factor That Controls The Developmental Timing Of Transcription From The Insulin/Insulin-Like Growth Factor Gene Ins-33 By Direct Dna Binding, Marta Hristova, Darcy Birse, Yang Hong, Victor Ambros Dec 2005

The Caenorhabditis Elegans Heterochronic Regulator Lin-14 Is A Novel Transcription Factor That Controls The Developmental Timing Of Transcription From The Insulin/Insulin-Like Growth Factor Gene Ins-33 By Direct Dna Binding, Marta Hristova, Darcy Birse, Yang Hong, Victor Ambros

Dartmouth Scholarship

A temporal gradient of the novel nuclear protein LIN-14 specifies the timing and sequence of stage-specific developmental events in Caenorhabditis elegans. The profound effects of lin-14 mutations on worm development suggest that LIN-14 directly or indirectly regulates stage-specific gene expression. We show that LIN-14 can associate with chromatin in vivo and has in vitro DNA binding activity. A bacterially expressed C-terminal domain of LIN-14 was used to select DNA sequences that contain a putative consensus binding site from a pool of randomized double-stranded oligonucleotides. To identify candidates for genes directly regulated by lin-14, we employed DNA microarray hybridization to compare …


The Nuclear Pore Complex And The Dead Box Protein Rat8p/Dbp5p Have Nonessential Features Which Appear To Facilitate Mrna Export Following Heat Shock, Christiane Rollenhagen, Christine A. Hodge, Charles N. Cole Jan 2004

The Nuclear Pore Complex And The Dead Box Protein Rat8p/Dbp5p Have Nonessential Features Which Appear To Facilitate Mrna Export Following Heat Shock, Christiane Rollenhagen, Christine A. Hodge, Charles N. Cole

Dartmouth Scholarship

Nuclear pore complexes (NPCs) play an essential role in RNA export. Nucleoporins required for mRNA export in Saccharomyces cerevisiae are found in the Nup84p and Nup82p subcomplexes of the NPC. The Nup82p subcomplex contains Nup82p, Rat7p/Nup159p, Nsp1p, Gle1p/Rss1p, and Rip1p/Nup42p and is found only on the cytoplasmic face of NPCs. Both Rat7p and Gle1p contain binding sites for Rat8p/Dbp5p, an essential DEAD box protein and putative RNA helicase. Rip1p interacts directly with Gle1p and is the only protein known to be essential for mRNA export after heat shock but not under normal growth conditions. We report that in cells lacking …


Rhythmic Binding Of A White Collar-Containing Complex To The Frequency Promoter Is Inhibited By Frequency, Allan C. Froehlich, Jennifer J. Loros, Jay C. Dunlap May 2003

Rhythmic Binding Of A White Collar-Containing Complex To The Frequency Promoter Is Inhibited By Frequency, Allan C. Froehlich, Jennifer J. Loros, Jay C. Dunlap

Dartmouth Scholarship

The biological clock of Neurospora crassa includes interconnected transcriptional and translational feedback loops that cause both the transcript and protein encoded by the frequency gene (frq) to undergo the robust daily oscillations in abundance, which are essential for clock function. To understand better the mechanism generating rhythmic frq transcript, reporter constructs were used to show that the oscillation in frq message is transcriptionally regulated, and a single cis-acting element in the frq promoter, the Clock Box (C box), is both necessary and sufficient for this rhythmic transcription. Nuclear protein extracts used in binding assays revealed that a White Collar (WC)-1- …


Circadian Clock-Specific Roles For The Light Response Protein White Collar-2, Michael A. Collett, Jay C. Dunlap, Jennifer J. Loros Apr 2001

Circadian Clock-Specific Roles For The Light Response Protein White Collar-2, Michael A. Collett, Jay C. Dunlap, Jennifer J. Loros

Dartmouth Scholarship

To understand the role of white collar-2 in theNeurospora circadian clock, we examined alleles ofwc-2 thought to encode partially functional proteins. We found that wc-2 allele ER24 contained a conservative mutation in the zinc finger. This mutation results in reduced levels of circadian rhythm-critical clock gene products, frq mRNA and FRQ protein, and in a lengthened period of the circadian clock. In addition, this mutation altered a second canonical property of the clock, temperature compensation: as temperature increased, period length decreased substantially. This temperature compensation defect correlated with a temperature-dependent increase in overall FRQ protein levels, with the …


Dissection Of A Circadian Oscillation Into Discrete Domains, Martha W. Merrow, Norman Y. Garceau, Jay C. Dunlap Apr 1997

Dissection Of A Circadian Oscillation Into Discrete Domains, Martha W. Merrow, Norman Y. Garceau, Jay C. Dunlap

Dartmouth Scholarship

The circadian oscillator in Neurospora is a negative feedback loop involving as principal players the products of the frequency (frq) locus. frq encodes multiple forms of its protein product FRQ, which act to depress the amounts of frq transcript. In this scheme there are two discrete and separable steps to the circadian cycle, negative feedback itself (repression) in which FRQ acts to decrease the levels of its own transcript, and recovery from repression (derepression) in which frq transcript levels return to peak amounts. By introducing an exogenously regulatable frq transgene into a frq loss-of-function strain (frq9 …


Transcriptional Activity Of Core Binding Factor-Alpha (Aml1) And Beta Subunits On Murine Leukemia Virus Enhancer Cores., Ari L. Zaiman, Amy F. Lewis, Barbara E. Crute, N. A. Speck, Jack Lenz May 1995

Transcriptional Activity Of Core Binding Factor-Alpha (Aml1) And Beta Subunits On Murine Leukemia Virus Enhancer Cores., Ari L. Zaiman, Amy F. Lewis, Barbara E. Crute, N. A. Speck, Jack Lenz

Dartmouth Scholarship

Core binding factor (CBF), also known as polyomavirus enhancer-binding protein 2 and SL3 enhancer factor 1, is a mammalian transcription factor that binds to an element termed the core within the enhancers of the murine leukemia virus family of retroviruses. The core elements of the SL3 virus are important genetic determinants of the ability of this virus to induce T-cell lymphomas and the transcriptional activity of the viral long terminal repeat in T lymphocytes. CBF consists of two subunits, a DNA binding subunit, CBF alpha, and a second subunit, CBF beta, that stimulates the DNA binding activity of CBF alpha. …


The Leukemic Core Binding Factor Beta-Smooth Muscle Myosin Heavy Chain (Cbf Beta-Smmhc) Chimeric Protein Requires Both Cbf Beta And Myosin Heavy Chain Domains For Transformation Of Nih 3t3 Cells., Amitav Hajra, Pu Liu, Qing Wang, Christine Kelley Mar 1995

The Leukemic Core Binding Factor Beta-Smooth Muscle Myosin Heavy Chain (Cbf Beta-Smmhc) Chimeric Protein Requires Both Cbf Beta And Myosin Heavy Chain Domains For Transformation Of Nih 3t3 Cells., Amitav Hajra, Pu Liu, Qing Wang, Christine Kelley

Dartmouth Scholarship

An inversion of chromosome 16 associated with the M4Eo subtype of acute myeloid leukemia produces a chimeric protein fusing the beta subunit of the transcription factor core binding factor (CBF beta) to the tail region of smooth muscle myosin heavy chain (SMMHC). We investigated the oncogenic properties of this CBF beta-SMMHC chimeric protein using a 3T3 transformation assay. NIH 3T3 cells expressing CBF beta-SMMHC acquired a transformed phenotype, as indicated by their ability to form foci, grow in soft agarose, and form tumors in nude mice. Cells expressing normal CBF beta or the SMMHC tail domain did not become transformed. …


A Phorbol Ester Response Element Within The Human T-Cell Receptor Beta-Chain Enhancer., Haydn M. Prosser, David Wotton, Anne Gegonne, Jacques Ghysdael, Shuwen Wang, Nancy A. Speck, Michael J. Owen Oct 1992

A Phorbol Ester Response Element Within The Human T-Cell Receptor Beta-Chain Enhancer., Haydn M. Prosser, David Wotton, Anne Gegonne, Jacques Ghysdael, Shuwen Wang, Nancy A. Speck, Michael J. Owen

Dartmouth Scholarship

The activity of the T-cell receptor beta-chain gene enhancer is increased by activators of the protein kinase C pathway during T-cell activation. Analysis of mutant enhancer constructs identified two elements, beta E2 and beta E3, conferring phorbol ester inducibility. Multimerized beta E2 acted in isolation as a phorbol ester-responsive element. Both beta E2 and beta E3, which contain a consensus Ets-binding site, were shown to bind directly to the product of the c-ets-1 protooncogene. Both regions also bound a second factor, core-binding factor. Mutation of the beta E2 Ets site abolished the inducibility of the beta E2 multimer. beta E2 …


Characterization Of The Formate (For) Locus, Which Encodes The Cytosolic Serine Hydroxymethyltransferase Of Neurospora Crassa., C. Robertson Mcclung, Cynthia R. Davis, Karen M. Page, Sylvia A. Denome Apr 1992

Characterization Of The Formate (For) Locus, Which Encodes The Cytosolic Serine Hydroxymethyltransferase Of Neurospora Crassa., C. Robertson Mcclung, Cynthia R. Davis, Karen M. Page, Sylvia A. Denome

Dartmouth Scholarship

Serine hydroxymethyltransferase (SHMT) occupies a central position in one-carbon (C1) metabolism, catalyzing the reaction of serine and tetrahydrofolate to yield glycine and 5,10-methylenetetrahydrofolate. Methylenetetrahydrofolate serves as a donor of C1 units for the synthesis of numerous compounds, including purines, thymidylate, lipids, and methionine. We provide evidence that the formate (for) locus of Neurospora crassa encodes cytosolic SHMT. The for+ gene was localized to a 2.8-kb BglII fragment by complementation (restoration to formate-independent growth) of a strain carrying a recessive for allele, which confers a growth requirement for formate. The for+ gene encodes a polypeptide of 479 amino acids which shows …


The Growth Of Simian Virus 40 (Sv40) Host Range/Adenovirus Helper Function Mutants In An African Green Monkey Cell Line That Constitutively Expresses The Sv40 Agnoprotein., Terryl P. Stacy, Michele Chamberlain, Susan Carswell, Charles N. Cole Jul 1990

The Growth Of Simian Virus 40 (Sv40) Host Range/Adenovirus Helper Function Mutants In An African Green Monkey Cell Line That Constitutively Expresses The Sv40 Agnoprotein., Terryl P. Stacy, Michele Chamberlain, Susan Carswell, Charles N. Cole

Dartmouth Scholarship

The simian virus 40 T-antigen carboxy-terminal mutants, dlA2459 and dlA2475, are cell line and temperature dependent for growth and plaque formation in monkey kidney cells. Although these mutants did form plaques on BSC-1 cells at 37 degrees C, they were about fivefold less efficient for plaque formation than wild-type simian virus 40. These mutants did not grow in CV-1 cells and did not synthesize agnoprotein in those cells. CV-1 cells which constitutively express the agnoprotein were permissive for mutant plaque formation. However, late mRNAs, virion proteins, and progeny virion yields did not accumulate to wild-type levels during mutant infection of …


Simian Virus 40 Host Range/Helper Function Mutations Cause Multiple Defects In Viral Late Gene Expression., Terryl Stacy, Michele Chamberlain, Charles N. Cole Dec 1989

Simian Virus 40 Host Range/Helper Function Mutations Cause Multiple Defects In Viral Late Gene Expression., Terryl Stacy, Michele Chamberlain, Charles N. Cole

Dartmouth Scholarship

Simian virus 40 (SV40) deletion mutants dlA2459 and dlA2475 express T antigens that lack the normal carboxy terminus. These mutants are called host range/helper function (hr/hf) mutants because they form plaques at 37 degrees C on BSC-1 and Vero monkey kidney cell lines but not on CV-1p monkey kidney cells. Wild-type SV40 can provide a helper function to permit growth of human adenoviruses in monkey kidney cells; the hr/hf mutants cannot. Progeny yields of hr/hf mutants are also cold sensitive in all cell lines tested. Patterns of viral macromolecular synthesis in three cell lines (Vero, BSC-1, and CV-1) at three …


Linker Insertion Mutants Of Simian Virus 40 Large T Antigen That Show Trans-Dominant Interference With Wild-Type Large T Antigen Map To Multiple Sites Within The T-Antigen Gene., Jiyue Y. Zhu, Charles N. Cole Nov 1989

Linker Insertion Mutants Of Simian Virus 40 Large T Antigen That Show Trans-Dominant Interference With Wild-Type Large T Antigen Map To Multiple Sites Within The T-Antigen Gene., Jiyue Y. Zhu, Charles N. Cole

Dartmouth Scholarship

Linker insertion mutants affecting the simian virus 40 (SV40) large tumor (T) antigen were constructed by inserting a 12-base-pair oligonucleotide linker into restriction endonuclease cleavage sites located within the early region of SV40. One mutant, with the insertion at amino acid 5, was viable in CV-1p and BSC-1 cells, indicating that sequences very close to the amino terminus of large T could be altered without affecting the lytic infection cycle of SV40. All other mutants affecting large T were not viable. In complementation assays between the linker insertion mutants and either a late-gene mutant, dlBC865, or a host range/helper function …


Patterns Of Polyadenylation Site Selection In Gene Constructs Containing Multiple Polyadenylation Signals., Roger Denome, Charles Cole Nov 1988

Patterns Of Polyadenylation Site Selection In Gene Constructs Containing Multiple Polyadenylation Signals., Roger Denome, Charles Cole

Dartmouth Scholarship

We have constructed a series of plasmids containing multiple polyadenylation signals downstream of the herpes simplex virus type 1 (HSV) thymidine kinase (tk)-coding region. The signals used were from the simian virus 40 (SV40) late gene, the HSV tk gene, and an AATAAA-containing segment of the SV40 early region. This last fragment signals polyadenylation poorly in our constructs and not at all during SV40 infection. All plasmids contained the SV40 origin of replication. Plasmids were transfected into Cos-1 cells; after 48 h, cytoplasmic RNA was isolated and the quantity and 3'-end structure of tk mRNAs was analyzed by using S1 …


Molecular Cloning And Sequence Analysis Of The Plasmodium Falciparum Dihydrofolate Reductase-Thymidylate Synthase Gene., David J. Bzik, Wu-Bo Li, Toshihiro Horii, Joseph Inselburg Dec 1987

Molecular Cloning And Sequence Analysis Of The Plasmodium Falciparum Dihydrofolate Reductase-Thymidylate Synthase Gene., David J. Bzik, Wu-Bo Li, Toshihiro Horii, Joseph Inselburg

Dartmouth Scholarship

Genomic DNA clones that coded for the bifunctional dihydrofolate reductase (DHFR) and thymidylate synthase (TS) (DHFR-TS) activities from a pyrimethamine-sensitive strain of Plasmodium falciparum were isolated and sequenced. The deduced DHFR-TS protein contained 608 amino acids (71,682 Da). The coding region for DHFR-TS contained no intervening sequences and had a high A + T content (75%). The DHFR domain, in the amino-terminal portion of the protein, was joined by a 94-amino acid junction sequence to the TS domain in the carboxyl-terminal portion of the protein. The TS domain was more conserved than the DHFR domain and both P. falciparum domains …


Fine-Structure Analysis Of The Processing And Polyadenylation Region Of The Herpes Simplex Virus Type 1 Thymidine Kinase Gene By Using Linker Scanning, Internal Deletion, And Insertion Mutations., Fang Zhang, Roger M. Denome, Charles N. Cole Dec 1986

Fine-Structure Analysis Of The Processing And Polyadenylation Region Of The Herpes Simplex Virus Type 1 Thymidine Kinase Gene By Using Linker Scanning, Internal Deletion, And Insertion Mutations., Fang Zhang, Roger M. Denome, Charles N. Cole

Dartmouth Scholarship

Most eucaryotic mRNAs are polyadenylated. In higher eucaryotes, the sequence AATAAA is located 7 to 30 base pairs (bp) upstream from the site of processing and polyadenylation and is a critical part of the signal for processing and polyadenylation. Efficient cleavage and polyadenylation also require sequences downstream of polyadenylation sites. The herpes simplex virus type 1 thymidine kinase (tk) gene contains two copies of the AATAAA hexanucleotide and a GT box (18 of 19 consecutive residues are G or T) previously shown to be required for efficient processing and polyadenylation of tk mRNA (C. N. Cole and T. P. Stacy, …


Identification Of Sequences In The Herpes Simplex Virus Thymidine Kinase Gene Required For Efficient Processing And Polyadenylation., Charles N. Cole, Terryl P. Stacy Aug 1985

Identification Of Sequences In The Herpes Simplex Virus Thymidine Kinase Gene Required For Efficient Processing And Polyadenylation., Charles N. Cole, Terryl P. Stacy

Dartmouth Scholarship

The herpes simplex virus (HSV) type 1 thymidine kinase gene (tk) was resected from its 3' end with BAL 31 exonuclease. Two sets of plasmids were isolated that lacked information distal to the two copies of the hexanucleotide 5'-AATAAA-3' located at the 3' end of the HSV tk gene. The presence of a simian virus 40 origin of DNA replication in each plasmid facilitated analysis of patterns of transcription in transfected Cos-1 monkey cells. Transcription analyses were performed with an S1 nuclease protection assay. Efficient processing and polyadenylation at the normal site still occurred when all sequences more than 44 …


Two Separable Functional Domains Of Simian Virus 40 Large T Antigen: Carboxyl-Terminal Region Of Simian Virus 40 Large T Antigen Is Required For Efficient Capsid Protein Synthesis., Joanne Tornow, Maryellen Polvino-Bodnar, George Santangelo, Charles N. Cole Feb 1985

Two Separable Functional Domains Of Simian Virus 40 Large T Antigen: Carboxyl-Terminal Region Of Simian Virus 40 Large T Antigen Is Required For Efficient Capsid Protein Synthesis., Joanne Tornow, Maryellen Polvino-Bodnar, George Santangelo, Charles N. Cole

Dartmouth Scholarship

The carboxyl-terminal portion of simian virus 40 large T antigen is essential for productive infection of CV-1 and CV-1p green monkey kidney cells. Mutant dlA2459, lacking 14 base pairs at 0.193 map units, was positive for viral DNA replication, but unable to form plaques in CV-1p cells (J. Tornow and C.N. Cole, J. Virol. 47:487-494, 1983). In this report, the defect of dlA2459 is further defined. Simian virus 40 late mRNAs were transcribed, polyadenylated, spliced, and transported in dlA2459-infected cells, but the level of capsid proteins produced in infected CV-1 green monkey kidney cells was extremely low. dlA2459 large T …