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L K Miller

Publications and source records attributed to L K Miller.

At least 127 records · Page 7Linked to original sources
PubMed1990

Thermally inactivated simian virus 40 tsA58 mutant T antigen cannot initiate viral DNA replication in vitro.

The mutation in the temperature-sensitive tsA58 mutant T antigen (Ala-438----Val) lies within the presumptive ATP-binding fold. We have constructed a recombinant baculovirus that expresses large quantities of the tsA58 T antigen in infected insect cells. The mutant T antigen mediated simian virus 40 origin-containing DNA (ori-DNA) synthesis in vitro to nearly the same extent as similar quantities of wild-type T antigen at 33 degrees C. However, if wild-type and tsA58 T antigens were heated at 41 degrees C in replication extracts prior to addition of template DNA, the tsA58 T antigen but not the wild type was completely inactivated. The mutant protein displayed greater thermosensitivity for many of the DNA replication activities of T antigen than did the wild-type protein. Some of the replication functions of tsA58 T antigen were differentially affected depending on the presence or absence of ATP during the preheating period. When tsA58 T antigen was preheated in the presence of ATP at 41 degrees C for a time sufficient to completely inactivate its ability to replicate ori-DNA in vitro, it displayed substantial ATPase and normal DNA helicase activities. Conversely, when preheated in the absence of nucleotide, it completely lost both ATPase and helicase activities. Preheating tsA58 T antigen, even in the presence of ATP, led to drastic reductions in its ability to bind to and unwind DNA containing the replication origin. The mutant T antigen also displayed thermosensitivity for binding to and unwinding nonspecific double-stranded DNA in the presence of ATP. Our results suggest that the interactions of T antigen with ATP that are involved in T-antigen DNA binding and DNA helicase activities are different. Moreover, we conclude, consistent with its phenotype in vivo, that the tsA58 T antigen is defective in the initiation but not in the putative elongation functions of T antigen in vitro.

Animals↗
PubMed1990

Regulation of expression of a baculovirus ecdysteroid UDPglucosyltransferase gene.

The Autographa californica nuclear polyhedrosis virus egt gene encodes an ecdysteroid UDPglucosyltransferase which catalyzes the transfer of glucose from UDPglucose to ecdysteroid insect molting hormones. Expression of this gene allows the virus to block molting and pupation of infected insect larvae. In this study, we present the nucleotide sequence of the A. californica nuclear polyhedrosis virus egt gene and characterize egt gene expression at the transcriptional and translational levels. egt was transcribed as two 5'-coterminal mRNAs early in infection. Transferase activity was detected in infected cells and in the extracellular fluid by 3 h after infection. The majority of the activity accumulated in the extracellular fluid. We show that the egt gene product is a 60-kilodalton protein which is secreted from the infected cell. The egt gene is located in a region of the A. californica nuclear polyhedrosis virus genome which exhibited hypervariability in serially passaged virus stocks. Nucleotide sequence analysis revealed that the most common deletion occurring in these serially passaged virus isolates is located in the egt gene.

Amino Acid Sequence↗
PubMed1990

Transcription of the baculovirus polyhedrin gene reduces the levels of an antisense transcript initiated downstream.

A late 3.2-kilobase (kb) RNA initiated approximately 2 kb downstream of the 3' end of the Autographa californica nuclear polyhedrosis virus polyhedrin-coding sequence and traversed the polyhedrin gene in an antisense direction. This RNA was sense RNA for the two open reading frames flanking the polyhedrin gene. A mutant virus, vXpoly, which differs from wild-type virus only at the essential RNA initiation site in the polyhedrin promoter, exhibited higher levels of the 3.2-kb RNA than did wild-type virus during the polyhedrin transcriptional phase. Thus, transcription of the polyhedrin gene down regulates the levels of this 3.2-kb RNA.

Animals↗
PubMed1990

Plasma free and non-sex-hormone-binding-globulin-bound testosterone are decreased in obese men in proportion to their degree of obesity.

It is known that plasma total testosterone (T) is decreased in obese men in proportion to the degree of obesity, but similar information is not available for plasma free T and non-sex-hormone-binding globulin (SHBG)-bound T. We measured the 24-h mean plasma total T in 48 healthy (non-weight-stable men, aged 18-55 yr, with body mass indexes (BMI) ranging from 21-95 kg/m2. Free T and non-SHBG-bound T were calculated using the measured total T, the concentrations of albumin and SHBG, and the association constants of T to albumin and SHBG. Total body fat content was measured by deuterium-water isotope dilution. Findings were as follows. 1) BMI was very highly correlated with total body fat content (r = 0.96; P less than 0.001); thus, the degree of obesity can be calculated just as appropriately from simple height and weight measurements as from measurements of total body fat content. 2) Total, non-SHBG-bound, and free T were all highly correlated inversely with BMI; for total T, r = -0.727, P less than 0.01; for non-SHBG-bound T, r = 0.677, P less than 0.01; and for free T, r = -0.653, P less than 0.01. Thus, free T and non-SHBG-bound T are decreased in obese men in proportion to the degree of obesity, just as is the case for total T; percentage-wise, the decrease was the same for all 3 parameters.

Adult↗
PubMed1990

Musical aptitude and adaptive behavior of people with mental retardation.

Musical aptitude was assessed in 16 adults nominated as having special musical interests and/or skills and 16 matched comparison adults. Information pertaining to strengths and weaknesses in adjustment was also obtained. Musical target subjects scored higher on the test of musical aptitude, particularly if they played a musical instrument. Evidence for difficulties in adjustment associated with musical skill or interest was mixed, although, in general, the results suggested no pervasive maladjustment among those with exceptional skill combined with mental retardation.

Adaptation, Psychological↗
PubMed1989

Downstream sequences augment transcription from the essential initiation site of a baculovirus polyhedrin gene.

A series of recombinant baculoviruses containing linker-substituted polyhedrin promoters attached to a reporter gene encoding chloramphenicol acetyl transferase (CAT) were constructed and tested for expression of the gene. The major determinant for promoter activity was narrowed to within eight nucleotides, TAAGTATT, at the start point of polyhedrin mRNA transcription. Mutations within TAAGTATT blocked initiation of transcription from this site and resulted in a 2000-fold decrease in CAT activity. Linker mutations from 12 to 22 bases upstream from the TAAGTATT sequence increased the steady-state levels of RNAs initiated within TAAGTATT and increased CAT expression by up to 50%. Mutations downstream from TAAGTATT and within the region specifying the untranslated RNA leader diminished transcriptional initiation at TAAGTATT and decreased CAT activity two- to 20-fold. The half-lives of CAT RNAs were not noticeably affected by mutations in the untranslated RNA leader region and thus RNA turn-over was not responsible for the reduced levels of these CAT RNAs. Nuclear run-on analysis of two mutant viruses showed that these mutations decrease the rate of transcriptional initiation. Transcriptional initiation thus appears to be the major means of polyhedrin gene regulation. The data define promoter-related roles for TAAGTATT and the sequences specifying the untranslated mRNA leader in transcriptional initiation. A model by which the viral-induced RNA polymerase distinguishes late and very late initiation sites is proposed.

Base Sequence↗
PubMed1989

A baculovirus blocks insect molting by producing ecdysteroid UDP-glucosyl transferase.

The predicted amino acid sequence of a newly identified gene of the insect baculovirus Autographa californica nuclear polyhedrosis virus was similar to several uridine 5'-diphosphate (UDP)-glucuronosyl transferases and at least one UDP-glucosyl transferase. Genetic and biochemical studies confirmed that this gene encodes an ecdysteroid UDP-glucosyl transferase (egt). This enzyme catalyzes the transfer of glucose from UDP-glucose to ecdysteroids, which are insect molting hormones. Expression of the egt gene allowed the virus to interfere with normal insect development so that molting was blocked in infected larvae of fall armyworm (Spodoptera frugiperda).

Amino Acid Sequence↗
PubMed1989

Insect baculoviruses: powerful gene expression vectors.

Baculovirus vectors have proven useful in producing high levels of biologically active eukaryotic proteins and providing cellular fractions which are enriched in the protein of interest. Expression occurs in infected insect cells which also provide a suitable environment for post-translational modification and folding of the protein product. Stable baculovirus vectors can be constructed rapidly with a minimum of viral manipulation.

DNA Viruses↗
PubMed1989

Hormonally active long-term culture of human ovarian cells: initial characterization.

At present, to our knowledge, there are no long-term hormonally active cultures of normal human stromal ovarian cells. This report describes a method of developing such a system. Normal human stromal ovarian cells from three patients were cultured in McCoy's 5A tissue culture medium at 37 degrees C, 5% CO2, 95% humidity. The cells rapidly acquired fibroblastic appearance and grew in monolayers. The cells were trypsinized and passaged weekly. Tissue culture medium was collected and assayed for progesterone. The cells were initially producing 33.2 +/- 2.64 ng/mg protein of progesterone. By the eighth to twelfth passage, however, progesterone was no longer detectable in the medium. When the cells of the 12th passage were incubated with cholesterol, progesterone production resumed (8.9 +/- 0.09 ng/mg protein). When pregnenolone was used as a substrate, progesterone production was also present (8.06 +/- 0.24 ng/mg protein). Moreover, in the cells incubated with pregnenolone, progesterone production could be stimulated by adding 50 ng/mL FSH, or 50 ng/mL insulin to the incubation medium. Progesterone content of the medium increased to 11.3 +/- 0.29 ng/mg protein and 10.97 +/- 0.54 ng/mg protein respectively (P less than .05). The cells were also able to convert androstenedione to estrone. When the cells were incubated with 3 mumol/L androstenedione, estrone content of the medium ranged from 318 +/- 13 to 382 +/- 14 pg/mg protein. This finding suggests that aromatase is present in cultured human ovarian cells. These cells have now been maintained for 12 passages. A hormonally active long-term culture of normal human ovarian cells could be a useful tool in studies of ovarian physiology.

Adult↗
PubMed1989

Sequence, transcription and translation of a late gene of the Autographa californica nuclear polyhedrosis virus encoding a 34.8K polypeptide.

A 1.4 kb region downstream of the DNA polymerase gene of Autographa californica nuclear polyhedrosis virus was sequenced. Two open reading frames (ORFs) were identified of 927 and 474 bases in length. The 927 base ORF encodes a 34.8K protein as determined by in vitro translation of both hybrid-selected RNA and RNA synthesized in vitro from a 927 base ORF template. The predicted amino acid sequence of the 34.8K polypeptide (p34.8) reveals a hydrophobic N terminus, two potential N-glycosylation sites, and potential sites for phosphorylation by casein kinase I and protein kinase C. The p34.8 gene has a strong codon usage bias which is strikingly different from that of the polyhedrin gene. The two 5' ends of the 927 base ORF transcripts initiate from an ATAAG sequence and a GTAAG sequence 11 and 87 bases upstream of the ATG codon respectively. A short upstream reading frame is present in the leader sequence of the longer RNA. The transcripts have multiple 3' ends; the most proximal endpoint correlates with a polyadenylation signal overlapping the translational termination codon of the 927 base ORF. Transcripts of the latter were not observed early in the infection cycle but appeared 6 h after infection and were maximally expressed at 12 to 24 h post-infection. The late nature of these transcripts was confirmed by their sensitivity to aphidicolin and cycloheximide, inhibitors of DNA replication and protein synthesis respectively. Attempts to construct viral mutants carrying a deletion of the p34.8 gene and fusion with the beta-galactosidase gene suggest that the former gene is essential for viral replication.

Amino Acid Sequence↗
PubMed1989

A baculovirus gene with a novel transcription pattern encodes a polypeptide with a zinc finger and a leucine zipper.

An Autographa californica nuclear polyhedrosis virus gene encoding a 30-kilodalton polypeptide with two different sequence motifs characteristic of DNA-binding proteins was identified immediately downstream of the major capsid protein gene (vp39). The gene, CG30, was characterized by sequencing, transcriptional mapping, in vitro translation of hybrid-selected RNA, and comparison of the derived polypeptide sequence with published data bases. The initial ATG of the 792-base-pair CG30 open reading frame is two nucleotides downstream of the vp39 terminal TAA codon. Early transcripts of CG30 initiate within the vp39 coding sequence. At late times, bicistronic transcripts initiate from the vp39 promoter, continue through CG30, and terminate at the same site as the early transcripts. In vitro translation of hybrid-selected early CG30 RNA yields a polypeptide of 30 kilodaltons. The predicted CG30 polypeptide sequence has characteristics of a eucaryotic transcriptional activator and is novel in having two potential DNA-binding domains. A stretch of acidic residues bridges a zinc finger at the amino terminus and a leucine zipper with a flanking basic region at the carboxyl terminus.

Amino Acid Sequence↗
PubMed1989

Identification, sequence, and transcriptional mapping of the major capsid protein gene of the baculovirus Autographa californica nuclear polyhedrosis virus.

The gene encoding the major capsid protein of the baculovirus Autographa californica nuclear polyhedrosis virus (AcMNPV) was identified, sequenced, and transcriptionally mapped. The location of the gene was determined by immunological screening of an expression library of AcMNPV open reading frame-beta-galactosidase fusions with an antibody raised to virus structural proteins. The DNA sequence of the corresponding region, which mapped within 56.6 and 58.0 map units on the AcMNPV genome, revealed a 1,040-base-pair open reading frame capable of encoding a 39-kilodalton polypeptide. The identity of the polypeptide was determined by Western blot (immunoblot) analysis of purified empty capsids with an antibody raised to the capsid-beta-galactosidase fusion protein. The identity of the peptide encoded by the gene was confirmed by immunoprecipitation of an in vitro translation product with RNA selected by hybridization to DNA sequences from the coding region of the gene. Transcripts of the capsid gene were analyzed by Northern (RNA) blots and mapped by nuclease protection and primer extension analysis. The capsid gene is transcribed maximally at 12 and 24 h postinfection but not in the presence of cycloheximide, a protein synthesis inhibitor, or aphidicolin, a viral DNA synthesis inhibitor, and is therefore classified as a late gene. The gene is transcribed in a counterclockwise direction with respect to the circular map. There are three transcriptional start sites, all containing the AGTAAG consensus sequence found at the start site of all late AcMNPV genes.

Amino Acid Sequence↗
PubMed1989

Changes in the hypothalamic-pituitary-gonadal axis in human immunodeficiency virus-infected homosexual men.

Serum total testosterone, total 17 beta-estradiol, LH, FSH, and PRL concentrations were measured by RIA in 59 homosexual men infected with the human immunodeficiency virus (32 clinically healthy antibody-positive men (HH+), 20 men with acquired immune deficiency syndrome (AIDS), and 7 men with AIDS-related complex (ARC). The results were compared with those of 26 antibody-negative homosexual men (HH-) who served as controls. The mean serum total testosterone concentration was significantly lower in the men with AIDS [414 +/- 230 (+/- SD) ng/dL (14.5 +/- 8.0)] than in the HH- men [550 +/- 172 ng/dL (19.0 +/- 6.0 nmol/L); P less than 0.05]. The mean serum LH level was significantly higher in the men with AIDS (26 +/- 14 vs. 14 +/- 4 IU/L in HH- men; P less than 0.01) and slightly but significantly higher in the men with ARC (19 +/- 8 IU/L; 0.10 greater than P greater than 0.05). Serum FSH also was significantly higher in the men with AIDS (P less than 0.05). Serum PRL was significantly higher in the men with ARC (10 +/- 2 micrograms/L; P less than 0.05) and AIDS (16 +/- 10 micrograms/L; P less than 0.001) than in the HH- men (8 +/- 3 micrograms/L). Serum sex hormone-binding globulin levels were similar in HH- men and men with AIDS as were serum T responses to hCG administration for 2 days. These results suggest that alterations of the hypothalamic-pituitary-gonadal axis indicative of primary hypogonadism accompany human immunodeficiency virus infection in homosexual men.

AIDS-Related Complex↗
PubMed1988

Synthesis of a gene coding for an insect-specific scorpion neurotoxin and attempts to express it using baculovirus vectors.

We have explored the possibility of improving baculovirus pesticides by incorporating an insect-specific neurotoxin gene into a baculovirus genome. A 112-bp gene (BeIt) encoding insectotoxin-1 of the scorpion Buthus eupeus was synthesized and cloned in Escherichia coli. For expression, BeIt was transferred to the DNA genome of Autographa californica nuclear polyhedrosis virus (AcMNPV). Three different recombinant AcMNPVs, carrying BeIt under the control of the strong AcMNPV polyhedrin promoter, were constructed and expression of BeIt was monitored upon infection of Spodoptera frugiperda (Sf) cells. Toxin expression was low using a recombinant virus in which BeIt was inserted 6 nucleotides (nt) downstream from the intact polyhedrin mRNA leader. More expression was observed when a signal-peptide was attached in-frame to the N terminus of BeIt. The highest level of expression was observed with a fusion gene comprised of the 58 N-terminal codons of polyhedrin fused to BeIt; however, the level of expression was ten- to twenty-fold below that for polyhedrin. Polyhedrin promoter-directed transcripts of all three recombinants accumulated to levels similar to those of wild-type polyhedrin transcripts, indicating that the limitation to expression of unfused BeIt was not at the level of transcription but rather at the posttranscriptional level including translation or protein stability. Paralytic activity of the toxin products was not detected.

Amino Acid Sequence↗
PubMed1988

Eight base pairs encompassing the transcriptional start point are the major determinant for baculovirus polyhedrin gene expression.

The effects of mutations within the 92-bp region immediately upstream from the translational initiation ATG of the polyhedrin gene of the baculovirus Autographa californica nuclear polyhedrosis virus (AcMNPV) were determined by plasmid transient expression assays in the presence of wild-type (wt) AcMNPV DNA. Clustered point mutations were generated by substitution of 10-bp stretches of the polyhedrin promoter/leader region with a 10-bp HindIII linker. Three of these linker scan (LS) mutations in the region from nucleotides (nt) -62 to -84 (relative to the original polyhedrin ATG at +1, +2, +3) had no effect or a mild stimulatory effect on reporter gene expression. One mutation immediately upstream (nt -52 to -60) from the transcription start point (at nt -50) reduced expression four-fold. Three overlapping mutations affecting 8 bp from nt -44 to -51 (encompassing the transcriptional start point) reduced expression by 1000-fold. A 1000-fold reduction was also observed for a total deletion of nt -1 and -92. Five LS mutations between nt -1 and -43 each reduced expression two- to five-fold, whereas combining an LS mutation and a 9-bp deletion mutation in the leader reduced expression approx. nine-fold. Reversing the orientation of the reporter gene along with the wt 92-bp upstream polyhedrin promoter/leader sequences resulted in slightly higher expression levels than those observed for the normal orientation indicating that all the essential cis-acting promoter elements, with the possible exception of long-range enhancer sequences, are located downstream from nt -92. Sequences of the AcMNPVhr5 enhancer (homologous region No. 5 of AcMNPV) had only a minor effect on expression from the polyhedrin promoter in transient assays. The results show that 8 bp encompassing the transcriptional start point, a sequence which is conserved in all late AcMNPV promoters, is essential for polyhedrin gene expression. Additional nucleotides within the leader region are necessary for optimal expression.

Base Sequence↗
PubMed1988

Regulation of host RNA levels during baculovirus infection.

During infection of the permissive host insect cell line Spodoptera frugiperda IPLB-SF-21 by the baculovirus Autographa californica nuclear polyhedrosis virus (AcMNPV), the levels of host actin, histone, and heat shock 70 (hsp70) RNAs are reduced substantially. Reduction of the host RNA levels occurs primarily during a narrow window of the replication process, from approximately 12 to 18 hr postinfection (p.i.), corresponding to the phase in which the extracellular form of the virus buds into the media. A late viral protein appears to be required for this reduction since cycloheximide, an inhibitor of cytosolic protein synthesis, and aphidicolin, an inhibitor of host and viral DNA polymerases, inhibit the reduction of actin and histone RNA levels. A cDNA corresponding to the carboxyl half of the S. frugiperda mitochondrial cytochrome c oxidase subunit III (COIII) gene was isolated, sequenced, and characterized. Two differentially regulated mitochondrial transcripts of this gene are observed. The level of the larger of these transcripts, which is dependent on active cytosolic protein synthesis, is reduced during virus infection in a fashion similar to that of the nuclear host genes. The smaller COIII transcript is stable until at least 24 hr p.i. but the level of this RNA eventually declines by 48 hr p.i.

Actins↗
PubMed1988

Weight gain during adolescent pregnancy. Associated maternal characteristics and effects on birth weight.

Prospective data from 696 adolescents who delivered at 37 weeks or more gestation were analyzed to determine factors associated with weight gain during pregnancy and effects of pregnancy gains on birth weight and other outcomes of pregnancy. Pregnancy weight gain was found to be associated with the following factors: mother's ethnicity, length of gestation, parity, and presence of pregnancy-related hypertension. Maternal weight gain during pregnancy markedly increased infant birth weight. The risk of a low birth-rate infant was greatly reduced (OR = 0.14; CL = 0.1-0.2), and the risk of a macrosomic infant was 13.1 times higher (OR = 13.1; CL = 8.9-19.2) in adolescents gaining 20 kg or more. There was no increased risk for Caesarean section, fetal/neonatal death, or neonatal intensive care unit admission based on maternal weight gain. No effect of prepregnant relative weight on maternal weight gain was detected. The effect of weight gain on birth weight was also independent of the maternal prepregnant relative weight.

Adolescent↗