bluuebunny/crossref_metadata_2025 huggingface dataset:
Developmental shifts in frequency distribution of polysomal mRNA and their posttranscriptional regulation in the sea urchin embryo.
Authors: Shepherd G W , Nemer M
Published: May 2006

The frequency distributions of polyadenylylated RNAs from the polysomes of sea urchin blastulae and gastrulae were estimated from their kinetics of hybridization with complementary DNA. Developmental decreases in complexity were observed among abundant, intermediate, and rare frequency classes. The class of highest abundance in the blastula polysomes had a complexity of 5.6 X 10(4) nucleotides and contained about 30 mRNA species, which divided into subsets according to developmental fate. Studies with purified DNA complementary to this abundant class revealed that five of these mRNA species remained abundant in the gastrula, wherein each comprised 2% of the polyadenylylated RNA in the polysomes. Approximately 5 species decreased to a nearly rare frequency and 20 were absent or at the limits of detection in polyadenylylated RNA of gastrula polysomes. These distinctly different developmental fates suggest distinct modes of regulation of mRNA concentration for different subsets. Focusing on the small number of abundant blastula mRNAs, we ascertained that those which were absent from gastrula polysomes were nevertheless represented in the gastrula nuclear RNA. Therefore, the appearance of abundant mRNA species in polysomes can be regulated by posttranscriptional processes.
Diffusion model for genotype-dependent migration
Authors: Nagylaki Thomas , Moody Michael
Published: May 2006

A diffusion model for the joint action of genotype-dependent migration and genotype-independent population regulation is derived and investigated. The diploid, monoecious population occupies a finite chain of equally spaced colonies; generations are discrete and nonoverlapping; mating is random in each colony. A boundary-value problem is deduced for the gene frequencies at a multiallelic locus in the absence of mutation, selection, and random drift. This problem is studied for two alleles and constant and uniform population density and drift and diffusion coefficients. All equilibria are shown to be monotone, and explicit conditions for a protected polymorphism are established. Two examples of asymptotically stable clines are presented. It is demonstrated that genotype dependence of the mean displacements is necessary to produce or maintain spatial differentiation of gene frequencies.
Antibodies specific for the carboxy- and amino-terminal regions of simian virus 40 large tumor antigen.
Authors: Walter G , Scheidtmann K H , Carbone A , Laudano A P , Doolittle R F
Published: May 2006

Antibodies specific for the amino- and carboxy-terminal portions of simian virus 40 large tumor (T) antigen were obtained by immunization of rabbits with synthetic peptides corresponding to these regions. The amino-terminal synthetic peptide has the sequence Ac-Met-Asp-Lys-Val-Leu-Asn-Arg-(Tyr). The tyrosine residue was introduced in order to couple the peptide to bovine serum albumin with bis-diazotized benzidine. The carboxy-terminal peptide has the sequence Lys-Pro-Pro-Thr-Pro-Pro-Pro-Glu-Pro-Glu-Thr. It was coupled to bovine serum albumin with glutaraldehyde. The antisera against both peptides reacted with large T antigen. The specificity of the immune reaction was demonstrated by inhibition experiments using excess synthetic peptides. Furthermore, fragments of T antigen encoded by the nondefective adenovirus 2-simian virus 40 hybrid viruses Ad2+ND2 and Ad2+ND4, which contain the carboxy terminus and lack the amino terminus of large T antigen, were precipitated only with antiserum to the carboxy-terminal peptide. Small T antigen was not precipitated with either serum, suggesting that the amino terminus of small T antigen has a conformation different from that of large T antigen or that it is sterically hindered by a host protein. The procedures used here are of general importance for identification and characterization of gene product.
Albumin Naskapi variant in North American Indians and Eti Turks.
Authors: Franklin S G , Wolf S I , Ozdemir Y , Yüregir G T , Isbir T , Blumberg B S
Published: May 2006

Both conventional polyacrylamide gel electrophoresis and a new type of electrophoretic screening procedure indicate that the polymorphic albumin variants Naskapi, found chiefly in the Naskapi Indians of Quebec, and Mersin, found in the Eti Turks of southeastern Turkey, are molecularly identical or very similar and that the amino acid substitution site in these variants is located between residues 330 and 446. This discovery is consistent with a genetic relationship between the Eti Turks and American Indians. We also report a new variant found in the Eti Turks, albumin Adana, which migrates similarly to albumin B on conventional gels but which our new system shows to differ from the common albumin A and albumin B by a substitution between residues 549 and 585.
Peptide inhibitor of morphine- and beta-endorphin-induced analgesia.
Authors: Lee N M , Friedman H J , Leybin L , Cho T M , Loh H H , Li C H
Published: May 2006

The synthetic beta-endorphin analogs with the omission of the NH2-terminal [Met]enkephalin segment [beta-endorphin-(6-31) and beta-endorphin-(20-31)] are shown to inhibit morphine- or beta-endorphin-induced analgesia in mice by the tail-flick test, whereas the synthetic NH2-terminal pentadecapeptide beta-endorphin-(1-15) has no inhibitory activity. This study raises the possibility that endogenous inhibiting peptides exist in the brain which play a role in the regulation of endorphin actions.
Location, function, and nucleotide sequence of a promoter for bacteriophage T3 RNA polymerase.
Authors: Adhya S , Basu S , Sarkar P , Maitra U
Published: May 2006

The major promoters for bacteriophage T3 RNA polymerase on the T3 genome have been mapped by DNA.RNA filter hybridization. One promoter is located in a 300-base-pair Hpa I restriction fragment near the genetic "left" end of T3 DNA. The sequence in the vicinity of the major initiation site of transcription in this region has been determined. A part of the (-)strand sequence is 5' T-A-T-T-T-A-C-C-C-T-C-A-C-T-A-A-A-G-+1 G-G-A-A-U 3'. Comparison of this sequence with the prototype 23-base-pair promoter sequence for bacteriophage T7 RNA polymerase shows a striking pattern of homology and divergence. Between positions -9 and +4, the sequences are virtually identical, whereas between positions -17 and -10, the sequences are quite different. It is postulated that these sequence subsets may perform different functions in transcription initiation by the phage RNA polymerases.
Cloning of yeast gene for trichodermin resistance and ribosomal protein L3.
Authors: Fried H M , Warner J R
Published: May 2006

Yeast cells sensitive to the eukaryotic protein synthesis inhibitor trichodermin have been transformed with autonomously replicating recombinant plasmids carrying DNA fragments of the genome of a trichodermin-resistant yeast strain. After selection for trichodermin-resistant cells, several transformants yielded a plasmid containing a 13.5-kilobase (kb) DNA fragment that encodes the trichodermin resistance gene, tcm1, and the gene for ribosomal protein L3, the largest of the yeast ribosomal proteins. Cells carrying this plasmid are resistant to trichodermin and to the related drug verrucarin A as well as to the unrelated drug anisomycin. This pattern of resistance is similar to that exhibited by strains carrying a chromosomal copy of tcm1. Moreover, polyribosomes prepared from transformed cells are resistant to trichodermin when tested in an in vitro protein synthesis assay. Subcloning of the 13.5-kb DNA fragment revealed that the gene for tcm1 and the gene for protein L3 are contained within a 3.2-kb segment. These results suggest that the gene for trichodermin resistance in yeast specifies ribosomal protein L3.
Rapidly evolving mouse alpha-globin-related pseudo gene and its evolutionary history.
Authors: Miyata T , Yasunaga T
Published: May 2006

The nucleotide sequences of a mouse pseudo alpha-globin gene and two adult alpha-globin genes from mouse and rabbit were compared. A close examination of sequence differences among the three genes revealed that the mouse pseudo alpha-globin gene was derived from one of the mouse alpha-globin genes about 24 million years ago by gene duplication and lost its original function, presumably due to loss of both the intervening sequences or frameshift mutations that prevented production of a functional globin polypeptide, and eventually became an inactive gene about 17 million years ago. After this event, this gene evolved at a very high rate, approximately 1.9 times the rate of synonymous codon change in productive genes. This suggests the presence of functional constraints against synonymous codon changes in normally functioning genes and also suggests that the "nucleotide arrangements" serve almost no important functions beside protein coding ability in the greater part of this gene, except for a very limited number of nucleotides. A continuous stretch of the pseudo alpha-globin gene consisting of a third exon and a 5' half of the 3' noncoding region shows marked sequence homology to the alpha-globin gene, suggesting transfer from one of the globin or globin-like genes by recombination very recently.
Inactivation of renal gamma-glutamyl transferase by 6-diazo-5-oxo-L-norleucylglycine, an inactive precursor of affinity-labeling reagent.
Authors: Inoue M , Morino Y
Published: May 2006

In vitro experiments showed that 6-diazo-5-oxo-L-norleucylglycine, a dipeptide analog of L-glutaminylglycine, inactivates gamma-glutamyl transferase bound to renal brush border membrane vesicles but does not inactivate the purified transferase. The rate of inactivation of the membrane-bound enzyme decreased markedly in the presence of dipeptides, such as L-leucylglycine and L-alanylglycine, or in the presence of o-phenanthroline, an inhibitor of renal peptidases. The presence of L-cysteinylglycine S-acetyldextran polymer (Mr 500,000), which does not permeate membranes, protected the membrane-bound transferase from inactivation by 6-diazo-5-oxo-L-norleucyglycine. This and other findings suggest that the norleucylglycine derivative was hydrolyzed by peptidase(s) bound to the outer surface of the brush border membranes and that the 6-diazo-5-oxo-L-norleucine thus released acts as an affinity-labeling reagent for the membrane-bound transferase. Similar effects were observed in vivo. Intravenous administration of 6-diazo-5-oxo-L-norleucylglycine to mice resulted in a marked decrease in renal transferase activity. Mice thus pretreated with 6-diazo-5-oxo-L-norleucylglycine, but not an untreated group, excreted significant amounts of S-carbamido[14C]methylglutathione in their urine within 30 min of intravenous administration of this compound. This finding suggests that the renal transferase was involved in the hydrolysis of the glutathione S-conjugate in the glomerular filtrate in vivo and that the administered 6-diazo-5-oxo-L-norleucylglycine underwent hydrolysis peptidase(s)-catalyzed to liberate 6-diazo-5-oxo-L-norleucine that reacted with the membrane-bound gamma-glutamyl transferase.
Immunohistochemical localization of cyclic GMP-dependent protein kinase in mammalian brain.
Authors: Lohmann S M , Walter U , Miller P E , Greengard P , De Camilli P
Published: May 2006

The distribution of cyclic GMP-dependent protein kinase in rat brain has been studied by an immunological approach involving radioimmunoassay and fluorescence immunohistochemistry. Data obtained by radioimmunoassay indicate that cyclic GMP-dependent protein kinase is 20- to 40-fold more concentrated in cerebellum than in other brain regions. Immunohistochemical experiments demonstrate that the high concentration of immunoreactivity of the protein kinase in cerebellum is attributable to Purkinje cells. Immunoreactivity in these cells is homogeneously distributed throughout the cell (perikarya, dendrites, and axons) with the exception of the nucleus. No other neurons either in the cerebellum or in other brain regions were stained by antiserum to the protein kinase. Immunoreactivity, however, was found throughout the brain on smooth muscle cells of blood vessels.
Chicken erythrocyte nucleus contains two classes of chromatin that differ in micrococcal nuclease susceptibility and solubility at physiological ionic strength.
Authors: Fulmer A W , Bloomfield V A
Published: May 2006

Inactive chromatin of the chicken erythrocyte nucleus is shown to consist of two distinct classes (I and S). I chromatin (approximately 60% of the total genome) is insoluble at greater than 0.1 M ionic strength whereas S chromatin (approximately 40% of the total genome) is soluble at all ionic strengths studied (0.01--0.3 M). These chromatins are released from nuclei upon digestion with micrococcal nuclease by two separate parallel processes that do not have a precursor--product relationship to each other. Isolated I-chromatin fragments show a progressive reduction in size from 250 to approximately 50 nucleosome equivalents with increasing digestion times at 0-2 degrees C. Prolonged digestion of nuclei at 37 degrees C results in conversion of I chromatin to mononucleosomes that are insoluble at greater than 30 mM NaCl. Isolated S-chromatin fragments show a constant size distribution, independent of digestion time, that peaks at approximately 35 nucleosome equivalents. Prolonged digestion of nuclei at 37 degrees C results in the conversion of S chromatin to mononucleosomes that are soluble at physiological ionic strength. Both I and S chromatins contain a full complement of histones with no nonhistone proteins.
Sequence-specific antibodies show that maturation of Moloney leukemia virus envelope polyprotein involves removal of a COOH-terminal peptide.
Authors: Green N , Shinnick T M , Witte O , Ponticelli A , Sutcliffe J G , Lerner R A
Published: May 2006

We followed maturation of the glycosylated envelope polyprotein Pr80env of a murine retrovirus by using antisera specific to subregions of the protein, including an antiserum directed against a synthetic peptide corresponding to the COOH-terminus of Pr80env. Shortly after synthesis and glycosylation, Pr80env is cleaved into two species, gp70 and Pr15E, that are found associated, perhaps through disulfide bonds, in infected cells. Pr15E is further cleaved at the time of virus maturation to form virus protein p15E. NH2-Terminal protein sequence analysis showed that Pr15E had an NH2 terminus in common with p15E. Pr15E, but not p15E, is precipitated by antibody against the COOH-terminal peptide; hence, p15E is missing a peptide at the COOH-terminus. Our data indicate that Pr15E is the predominant species in cells and p15E is the major species in virus.
Structure of the zeta chain of human embryonic hemoglobin.
Authors: Clegg J B , Gagnon J
Published: May 2006

The complete amino acid sequence of the zeta chain of human embryonic hemoglobin has been determined. It differs from human alpha globin at 57 of the 141 residues and several of the replacements are at positions of structural or functional importance, particularly in relationship to the Bohr effect and high intrinsic oxygen affinity which are characteristic of embryonic hemoglobins. The zeta-globin sequence is more closely related to other mammalian embryonic alpha-like globins than to human alpha, suggesting that there have been strong selective pressures to maintain these embryo-specific globins since their emergence several hundred million years ago.
Plasmid ColE1 incompatibility determined by interaction of RNA I with primer transcript.
Authors: Tomizawa J , Itoh T
Published: May 2006

Mutants of plasmid pNT7 that can coexist with plasmid pMB9 in growing bacteria have been isolated. These mutants show altered incompatibility properties and increased copy numbers. Each mutant has a single base change at or near the center of one of the three palindromes in the region that specifies two RNA species: a larger one (primer transcripts) that provides a primer for DNA replication and a smaller one (RNA I) that is the incompatibility-specific inhibitor of primer formation. In vitro transcription studies show that the single base changes affect both the ability of RNA I to inhibit primer formation and the sensitivity of primer formation to inhibition by RNA I. RNA I hybridizes to the primer transcript, and the rate of hybridization is reduced by the single base changes. Based on analyses of inhibition of in vitro primer formation by RNA I and of in vivo properties of the mutant plasmids, we conclude that incompatibility between two plasmids can be attributed to inhibition of primer formation on one of the plasmids by the RNA I of the other. Inhibition of primer formation by RNA I appears to be the mechanism that determines the copy number of pNT7 and its derivatives.
The cyc1-11 mutation in yeast reverts by recombination with a nonallelic gene: composite genes determining the iso-cytochromes c.
Authors: Ernst J F , Stewart J W , Sherman F
Published: May 2006

DNA sequence analysis of a cloned fragment directly established that the cyc1-11 mutation of iso-1-cytochrome c in the yeast Saccharomyces cerevisiae is a two-base-pair substitution that changes the CCA proline codon at amino acid position 76 to a UAA nonsense codon. Analysis of 11 revertant proteins and one cloned revertant gene showed that reversion of the cyc1-11 mutation can occur in three ways: a single base-pair substitution, which produces a serine replacement at position 76; recombination with the nonallelic CYC7 gene of iso-2-cytochrome c, which causes replacement of a segment in the cyc1-11 gene by the corresponding segment of the CYC7 gene; and either a two-base-pair substitution or recombination with the CYC7 gene, which causes the formation of the normal iso-1-cytochrome c sequence. These results demonstrate the occurrence of low frequencies of recombination between nonallelic genes having extensive but not complete homology. The formation of composite genes that share sequences from nonallelic genes may be an evolutionary mechanism for producing protein diversities and for maintaining identical sequences at different loci.
Genetic control of insulin receptors.
Authors: Goldfeld A E , Rubin C S , Siegel T W , Shaw P A , Schiffer S G , Gluecksohn-Waelsch S
Published: May 2006

Insulin-binding activity was measured in hepatocyte suspensions and liver membrane preparations from newborn mice homozygous for a perinatal-lethal deletion at and around the albino locus in chromosome 7. Cell suspensions and membrane preparations from the mutant mice exhibited only 20-25% of the specific hormone-binding activity observed in comparable preparations from their homozygous normal and heterozygous littermates. The decrease in insulin-binding activity appears to be attributable to a decrease in the number of insulin receptor sites per cell rather than to a change in receptor affinity. Gene sequences deleted at and around the albino locus are therefore instrumental in the regulation of insulin receptor concentration rather than in coding for the insulin receptor itself. The results of the present studies extend the identification of the regulatory functions exerted by the genes around the albino locus of the mouse.
Selective natural killer resistance in a clone of YAC lymphoma cells.
Authors: Roder J C , Beaumont T J , Kerbel R S , Haliotis T , Kozbor D
Published: May 2006

YAC lymphoma cells were treated with the mutagen N-methyl-N'-nitro-N-nitrosoguanidine and then cloned and subcloned. Of 51 clones, 3 were selected for further study. Ten-fold more natural killer (NK) effector cells were required to lyse YAC clone 6 and subclone 6-28 cells compared with clone 19 cells or the YAC parent cell line. The maximum plateau level of cytolysis of the NK-resistant (NKR) variants (20%) never approached that of the NK-sensitive (NKS) variants or YAC parental cells (60%) even after prolonged incubation (20 hr). NKR variants appeared with equal frequency (0.10) on cloning YAC cells that had not been treated with mutagen but these variants were highly unstable with respect to NK sensitivity and were not studied further. Cytolysis of both NKR and NKS lines was mediated by nylon-nonadherent asialo-GM1+ effector cells, and effectors from poly(I) . poly(C)-boosted mice preferentially lysed the NKS lines. The NKR alteration did not appear to change the NK target structure (NK-TS): (i) unlabeled NKR cells competed equally with NKS cells in reciprocal unlabeled-target competition assays; (ii) the frequency of target--effector conjugates was identical with NKR or NKS lines; and (iii) normal rabbit serum, which contains antibodies thought to react with the NK-TS, reacted equally against both NKR and NKS targets. The NKR alteration was selective for NK cells and did not result in a resistance to lysis in general; NKR and NKS variants were equally susceptible to (i) cytolysis mediated by alloimmune or lectin-dependent effector T cells and (ii) antibody- and complement-mediated lysis. These results are compatible with the hypothesis that the NKR variants have an altered acceptor site on the target cell membrane that normally binds the "lytic moiety" delivered by the effector cell.
Synthesis and processing of the alpha heavy chains of secreted and membrane-bound IgA.
Authors: Kikutani H , Sitia R , Good R A , Stavnezer J
Published: May 2006

We have compared the synthesis and processing of immunoglobulin alpha chains in two murine cell lines, a B cell lymphoma that expresses membrane-bound IgA and a hybridoma that secretes IgA. Results of biosynthetic labeling experiments demonstrated that membrane-bound and secreted alpha chains have two distinct intracellular precursors, of different molecular weights and isoelectric points. RNAs from both of these cell lines direct the synthesis in vitro of two alpha polypeptides of Mr 59,000 and 62,000, the larger one being the precursor for membrane-bound alpha chain and the smaller one being the precursor for secreted alpha chain. These cell lines each contain three RNAs, 1.7, 2.1, and 3.1 kilobases in length, which hybridize with cDNA for the alpha constant region and which are present in different concentrations. Our results suggest that the smallest RNA encodes the secreted alpha chain and one or both of the larger RNAs encode(s) the membrane-bound alpha chain.
Marginal underdominance at a stable equilibrium
Authors: Hastings Alan
Published: May 2006

An example is given of a stable equilibrium of a deterministic discrete-generation two-locus, two-allele, model at which marginal (or induced) underdominance holds. The example was found by using a numerical search procedure that involved picking random equilibria and finding possible fitnesses that would lead to those equilibria.
Thyrotropin-releasing hormone exerts rapid nuclear effects to increase production of the primary prolactin mRNA transcript.
Authors: Potter E , Nicolaisen A K , Ong E S , Evans R M , Rosenfeld M G
Published: May 2006

This report directly documents that a polypeptide hormone can regulate specific gene expression as a consequence of increasing the levels of a primary genomic transcript. The regulation and expression of the prolactin gene was studied in a cell line (GH4) derived from a rat pituitary tumor. These cells respond to addition of the hypothalamic tripeptide, thyrotropin-releasing hormone (TRH; thyroliberin), by elevation of the levels of mature prolactin mRNA and increase in prolactin biosynthesis. The message induction is preceded by, and apparently consequential to, a comparable rapid increase in the nuclear prolactin RNA precursors, including the putative primary transcript.
An amplified sensitivity arising from covalent modification in biological systems.
Authors: Goldbeter A , Koshland D E
Published: May 2006

The transient and steady-state behavior of a reversible covalent modification system is examined. When the modifying enzymes operate outside the region of first-order kinetics, small percentage changes in the concentration of the effector controlling either of the modifying enzymes can give much larger percentage changes in the amount of modified protein. This amplification of the response to a stimulus can provide additional sensitivity in biological control, equivalent to that of allosteric proteins with high Hill coefficients.
Suppression of malignancy in human cancer cells: issues and challenges.
Authors: Sabin A B
Published: May 2006

Analysis of the many, sometimes seemingly contradictory, reports on the partial suppression of malignancy in highly unstable rodent intraspecies and rodent--human hybrid cells emphasizes the limitations of this approach to the analysis of the basic nature of malignancy, especially in naturally occurring human cancers. During the past 5 years, Stanbridge and then Klinger reported complete suppression, not elimination, of malignancy [defined as capacity to produce progressively growing tumors in athymic (nude) mice] in stable hybrids of different human cancer cells with normal human fibroblasts or with differentiating epithelial keratinocytes and, importantly, also in stable hybrids of two parental cancers of different somatic cell origin. The nontumorigenic human hybrid cells are not rejected by some nonthymic immune mechanism of nude mice and survive in vascularized foci; the initial multiplication of these cells is stopped by some unknown proliferation controlling substance(s) to which their malignant parent(s) do not respond. The heritable properties of infinite multiplication in vitro, loss of contact inhibition, etc. remained in the nontumorigenic hybrids but, remarkably, the in vitro production of alpha human choriogonadotropin by HeLa cells was suppressed along with tumorigenicity and reappeared in the tumorigenic revertants. If it is assumed that human cancers of different somatic cell origin are caused by a loss of different specific regulatory genes, as the most recent data reviewed here suggest, the challenge is to determine in molecular terms what those missing genes are, how they function, and whether it may be possible to restore to the cancer cells what they have lost.
Canonical coordinates for plasma and hydrodynamic problems
Authors: Case K. M. , Roos A. M.
Published: May 2006

Many nonlinear equations arising in plasma physics, hydrodynamics, and solid-state physics can be written in Hamiltonian form. The full advantage of this is achieved only when the existence of canonical coordinates and momenta is known. Here such coordinates are exhibited for three large classes of equations—which seem to include almost all known completely integrable Hamiltonian systems.
A DNA fragment with an alpha-phosphorothioate nucleotide at one end is asymmetrically blocked from digestion by exonuclease III and can be replicated in vivo.
Authors: Putney S D , Benkovic S J , Schimmel P R
Published: May 2006

2'-Deoxyadenosine 5'-O-(1-thiotriphosphate) (dATP[alpha S]) was introduced into the 3' ends of DNA restriction fragments with Escherichia coli DNA polymerase I to give phosphorothioate internucleotide linkages. Such "capped" 3' ends were found to be resistant to exonuclease III digestion. Moreover, the resistance to digestion is great enough that, under conditions used by us, just one strand of a double helix is digested by exonuclease III when a cap is placed at only one end; when digestion is carried to completion, this results in production of intact single strands. When digestion with exonuclease III is limited and is followed by S1 nuclease treatment, double-stranded DNA fragments asymmetrically shortened from just one side are produced. In this was thousands of nucleotides can be selectively removed from one end of a restriction fragment. In vitro introduction of phosphorothioate linkages into one end of a linearized replicative plasmid, followed by exonuclease III and S1 nuclease treatments, gives rise to truncated forms that, upon circularization by blunt-end ligation, transform E. coli and replicate in vivo.
Optical activity and electronic absorption spectra of some simple nucleosides related to cytidine and uridine: all-valence-shell molecular orbital calculations.
Authors: Miles D W , Redington P K , Miles D L , Eyring H
Published: May 2006

The circular dichroism and electronic absorption of three simple model systems for cytidine and uridine have been measured to 190 nm. The molecular spectral properties (excitation wavelengths, oscillator strengths, rotational strengths, and polarization directions) and electronic transitional patterns were investigated by using wave functions of the entire nucleoside with the goal of establishing the reliability of the theoretical method. The computed electronic absorption quantities were shown to be in satisfactory agreement with experimental data. It was found that the computed optical rotatory strengths of the B2u and E1u electronic transitions and lowest observed n-pi transition are in good agreement with experimental values. Electronic transitions were characterized by their electronic transitional patterns derived from population analysis of the transition density matrix. The theoretical rotational strengths associated with the B2u and E1u transitions stabilize after the use of just a few singly excited configurations in the configuration interaction basis and, hypothetically, are more reliable as indicators of conformation in pyrimidine nucleosides related to cytidine.
Immunochemical studies on cultured fibroblasts from patients with inherited methylmalonic acidemia.
Authors: Kolhouse J F , Utley C , Fenton W A , Rosenberg L E
Published: May 2006

We developed a radioimmunoassay to quantitate material crossreacting immunochemically with human methylmalonyl-CoA mutase (methylmalonyl-CoA CoA-carbonylmutase, EC 5.4.99.2), and have applied this assay to extracts of fibroblasts from controls and from 32 patients with methylmalonic acidemia due to inherited deficiencies in mutase activity. Four control lines had an average of 237 ng of crossreacting material (CRM) per mg of cell protein (range, 193-297 ng/mg). Mutant lines from each of the four cbl complementation groups of inherited methylmalonic acidemia, which have normal amounts of mutase activity in vitro, contained quantities of CRM comparable to those of control lines. On the other hand, 28 cell lines from the mut complementation group, which express mutations at the structural gene locus for the mutase apoenzyme, contained widely diverse amounts of CRM. Each of seven lines from the mut- subgroup, whose residual mutase activity reflects the presence of a structurally altered mutase protein with reduced affinity for cofactor, had detectable CRM ranging from 20% to 100% of control. The 21 lines from the mut0 group, which have no detectable mutase activity in vitro, fell into two populations with regard to CRM: 9 lines had detectable CRM ranging from 3% to 40% of control; 12 others had no detectable CRM (limit of detectability, less than 1% of control). These results emphasize the wide range of mutations at a single structural gene locus that can result in deficient enzyme activity.
Marfan syndrome: abnormal alpha 2 chain in type I collagen.
Authors: Byers P H , Siegel R C , Peterson K E , Rowe D W , Holbrook K A , Smith L T , Chang Y H , Fu J C
Published: May 2006

Cells in culture from a woman with a variety of the Marfan syndrome produce two species of the alpha 2 chains of type I collagen. One alpha 2 chain appears normal; the abnormal chain has a higher apparent molecular weight than normal and migrates more slowly during electrophoresis in sodium dodecyl sulfate/polyacrylamide gels. A similar change in electrophoretic behavior is seen in the prepro alpha 2 chain and the pN alpha 2 chain (which contains the amino-terminal extension). Asymmetric cleavage of the pepsin-treated procollagens with a fibroblast collagenase locates the abnormal segment amino terminal to the cleavage site, and analysis of cyanogen bromide peptides of collagenase cleavage peptides and of whole collagens indicates that the abnormal segment is in either the alpha 2CB3 peptide or the short segment of alpha 2CB5 amino terminal to the collagenase site of the altered alpha 2 chain. The higher apparent molecular weight is consistent with the insertion of a small peptide fragment of approximately 20 amino acids. This alteration in chain size has marked effects on crosslinking because collagen from the patient's skin was 5-10 times more extractable in nondenaturing solvents than that from control skins. Although the abnormal chain was not found in several other individuals with the Marfan syndrome, these findings suggest that the phenotype may be the expression of a variety of primary structure alterations in the chains of type I collagen that interfere with normal crosslink formation.
Prostaglandins: Their role in egg-laying of the cricket
Teleogryllus commodus
Authors: Loher Werner , Ganjian Iraj , Kubo Isao , Stanley-Samuelson David , Tobe Stephen S.
Published: May 2006

Mating of the
Teleogryllus commodus
female causes increased oviposition mediated by PGE
2
, which is synthesized in the female's spermatheca from the precursor, arachidonic acid, in the presence of a PG-synthesizing complex. The latter, together with sperm, is transferred from the male to the female via a spermatophore. Only nanogram quantities of PGE
2
injected into oviduct are necessary to simulate mating-induced egg release.
N-Nitroso-N-methylurea elicits mammary cancer in resistant and sensitive rat strains.
Authors: Huggins C B , Ueda N , Wiessler M
Published: May 2006

A single intravenous (i.v.) injection of the water-soluble mammary carcinogen N-nitroso-N-methylurea (NMU; 35 mg/kg of body weight) elicited cancer of the breast in young female rats of two strains in the following incidence: Long-Evans strain, 4%; Sprague-Dawley strain, 70%. In sisters of these rats, a set of 5 i.v. injections of NMU (35 mg/kg at biweekly intervals) evoked mammary carcinoma as follows: Long-Evans strain, 76%; Sprague-Dawley strain, 100%. In its effectiveness in evoking mammary cancer in Sprague-Dawley rats, the lipid-soluble mammary carcinogen 7,8,12-trimethylbenz[a]anthracene exceeded NMU in rapidity of development of cancer and in tumor yield.
The Rogers-Ramanujan identities: Lie theoretic interpretation and proof
Authors: Lepowsky James , Wilson Robert Lee
Published: May 2006

The two Rogers-Ramanujan identities, which equate certain infinite products with infinite sums, are among the most intriguing of the classical formal power series identitites. It has been found by Lepowsky and Milne that the product side of each of them differs by a certain factor from the principally specialized character of a certain standard module for the Euclidean Kac-Moody Lie algebra
A
1
(1)
. On the other hand, the present authors have introduced an infinite-dimensional Heisenberg subalgebra [unk] of
A
1
(1)
which leads to a construction of
A
1
(1)
in terms of differential operators given by the homogeneous components of an “exponential generating function.” In the present announcement, we use [unk] to formulate a natural “abstract Rogers-Ramanujan identity” for an arbitrary standard
A
1
(1)
-module which turns out to coincide with the classical identities in the cases of the two corresponding standard modules. The abstract identity equates two expressions, one a product and the other a sum, for the principally specialized character of the space Ω of highest weight vectors or “vacuum states” for [unk] in the module. The construction of
A
1
(1)
leads to a concrete realization of Ω as the span of certain spaces of symmetric polynomials occurring as the homogeneous components of exponential generating functions. The summands in the Rogers-Ramanujan identities turn out to “count” the dimensions of these spaces. For general standard
A
1
(1)
-modules, we conjecture that the abstract identities agree with generalizations of the Rogers-Ramanujan identities due to Gordon, Andrews, and Bressoud.
Abundant pseudogenes for small nuclear RNAs are dispersed in the human genome.
Authors: Denison R A , Van Arsdell S W , Bernstein L B , Weiner A M
Published: May 2006

We have cloned and partially characterized 24 loci from the human genome which are complementary to U1, U2, or U3, the three major species of small nuclear RNA (snRNA) in HeLa cells. When compared to the known U1 (human) and U2 (rat) snRNA sequences, the DNA sequences we report here for the complementary regions from two of the clones, U1.11 and U2.7, reveal the presence of truncated and divergent gene copies. Furthermore, most if not all of the 24 cloned loci contain gene copies that are significantly divergent from the homologous HeLa snRNA species because DNA from every recombinant phage except U1.7 and U1.15 proved unable to form snRNA.DNA hybrids which protect full-length HeLa snRNA from ild digestion with ribonuclease T1. Hence, we refer to these loci as snRNA pseudogenes. In both clones U1.11 and U2.7, an element of the dominant middle repetitive DNA sequence family in the human genome, the Alu family, is located upstream from the snRNA pseudogene and in the same orientation. Alu elements in the same location and orientation relative to bona fide genes have previously been found in the human beta-globin gene cluster [Duncan, C. H., Biro, P. A., Choudary, P. V., Elder, J. T., Wang, R. C., Forget, G. B., deRiel, J. K. & Weissman, S. M. (1979) Proc. Natl. Acad. Sci. USA 76, 5095-5099]. We discuss the significance of these findings in relation to the nature of snRNA multigene families and other reported examples of pseudogenes.
Transport of sodium, chloride, and taurocholate by cultured rat hepatocytes
Authors: Scharschmidt Bruce F. , Stephens Jeffery E.
Published: May 2006

Transport of sodium, chloride, and taurocholate was studied in primary cultures of adult rat hepatocytes incubated in a balanced electrolyte solution containing 150 mM NaCl, various concentrations of taurocholate, and
22
Na,
36
Cl, [
3
H]taurocholate, and 3-
O
-[
3
H]methyl-D-glucose. Lithium chloride, choline chloride, or Na
2
SO
4
and mannitol were substituted isotonically for NaCl in selected studies. The steady-state intracellular concentrations of exchangeable sodium and chloride averaged 6.5 mM and 30.1 mM, respectively. Ouabain reversibly increased intracellular sodium concentration. Chloride entry rate was about double that of sodium. Unlike sodium entry, chloride entry rate increased nonlinearly with increasing extracellular concentration. Taurocholate entry exhibited both saturable and nonsaturable components; the former accounting for virtually all taurocholate uptake at concentrations comparable to those found
in vivo
. Taurocholate was actively concentrated by the cultured cells, with the steady-state intracellular-to-extracellular concentration ratio decreasing from over 50 to about 1 as extracellular taurocholate concentration was increased from 10 μM to 4 mM. Both the saturable uptake component and concentrative taurocholate transport were virtually abolished by substitution of choline or lithium for sodium or by addition of ouabain. Taurocholate entry rate first increased in a sigmoid fashion and then decreased as extracellular sodium concentration was increased from 0 to 150 mM. Sodium entry rate increased in the presence of added taurocholate with an average of one sodium ion accompanying each taurocholate molecule into the cell. These findings indicate that sodium and chloride differ strikingly in their mechanism and rate of entry into cultured rat hepatocytes and in their intracellular concentration. Moreover, hepatocytes concentrate taurocholate by a sodium-coupled mechanism with an apparently equimolar transport stoichiometry.
Euler-Poisson equations on Lie algebras and the
N
-dimensional heavy rigid body
Authors: Ratiu Tudor
Published: May 2006

The classical Euler-Poisson equations describing the motion of a heavy rigid body about a fixed point are generalized to arbitrary Lie algebras as Hamiltonian systems on coad-joint orbits of a tangent bundle Lie group. the
N
-dimensional Lagrange and symmetric heavy top are thereby shown to be completely integrable.
Nucleotide sequence at the termini of the DNA of Bacillus subtilis phage phi 29.
Authors: Escarmís C , Salas M
Published: May 2006

Phage phi 29 DNA cannot be phosphorylated with polynucleotide kinase and [gamma-32P]ATP because of the presence of a viral protein covalently linked to the 5' termini. The 5' ends can, however, be made susceptible to phosphorylation by treatment with alkali and alkaline phosphatase. Restriction fragments Hpa II C and Hpa II F, corresponding to the right and left ends of phi 29 DNA, respectively, were labeled at the 5' ends with polynucleotide kinase and [gamma-32P]ATP or at the 3' ends with terminal transferase and [alpha-32P]ATP or [alpha-32P]cordycepin 5'-triphosphate. After a secondary cleavage of the labeled fragments, the sequence of the first 150-180 nucleotides at the termini of phi 29 DNA was determined by the method of Maxam and Gilbert. The ends of phi 29 DNA are flush, and a six-nucleotides-long inverted terminal repetition was found. The functional implications of the sequences determined are discussed.
Tritium exchange on transfer RNA: slowly exchanging protons sensitive to a change in the dihydrouridine stem.
Authors: Ramstein J , Buckingham R H
Published: May 2006

Measurements of tritium exchange on tRNA were made for periods from 0.5 min to 8 hr after separation from labeled solvent. The exchange curve was analysed in terms of three kinetic classes of exchanging protons with half-lives of 5 hr (12 protons), 0.54 hr (37 protons) and about 3.5 min (58 protons) at 0 degrees C in 0.14 M K+/10 mM Mg2+. The behaviour under varying ionic conditions of protons in the slowest exchange class and of some protons in the intermediate class suggests that they are dependent on the tertiary structure of the molecule. Moreover, in the same range of exchange times characteristic of these latter protons, about 9 more protons were observed in the case of a mutant form of tRNA Trp, the UGA-suppressor species, than in the wild-type tRNATrp. These two species differ only in base 24 in the dihydrouridine stem. This dynamic difference between the wild-type and suppressor species may be related to a functionally important difference in coupling between the conformation of the molecule and interactions at the anticodon.
Instability and reiteration of DNA sequences within the vaccinia virus genome.
Authors: Moss B , Winters E , Cooper N
Published: May 2006

The sequence arrangement within the nontranscribed portion of the inverted terminal repetition of the vaccinia virus genome exists in quasi-stable and unstable forms that are not distinguishable on the basis of viral infectivity. The unstable forms, which composed about 20% of a serially passaged stock of virus, were recognized by terminal heterogeneity on restriction endonuclease analysis. Instead of a single terminal fragment from each end of the genome, an array of eight or more fragments differing in size by 1650-base-pair increments was detected. This feature was not eliminated by repeated plaque purification, indicating that the population of DNA molecules with various numbers of reiterations can rapidly evolve from the DNA of a single virus particle. However, at each successive round of plaque purification, about 20% of the unstable isolates revert back to the more stable form. Stable forms are characterized by the presence of a set of 13-17 tandem 70-base-pair repeats on each side of a 435-base-pair intervening sequence near both ends of the genome. In contrast, the unstable forms possess sets of tandem repeats and intervening sequences that alternate many times in series. The transition between the two genomic forms and the evolution of the unstable form appear to be mediated by recombinational events.
Spectroscopic characterization of compound C and related derivatives of cytochrome oxidase.
Authors: Carter K R , Antalis T M , Palmer G , Ferris N S , Woodruff W H
Published: May 2006

Magnetic circular dichroism and resonance Raman spectra have been obtained for three "oxygenated" derivatives of cytochrome c oxidase (ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1). The spectra are interpreted and four alternatives for the states of cytochrome a3 and Cuu are evaluated.
Construction of recombinant plasmids containing Xenopus immunoglobulin heavy chain DNA sequences.
Authors: Brown R D , Armentrout R W , Cochran M D , Cappello J , Langemeier S O
Published: May 2006

A recombinant cDNA plasmid containing Xenopus immunoglobulin heavy chain sequence has been constructed from Xenopus spleen poly(A)-containing RNA. The plasmid was identified by colony hybridization and a hybridization-translation assay and its identity was confirmed by DNA sequence analysis. The portion of the heavy chain sequence contained in the plasmid is 35% homologous to mammalian mu and gamma sequences. The mRNA corresponding to this plasmid is 2.5 kilobases, in close agreement with the size of mouse mu mRNA. RNA sequences complementary to the cloned sequence appear in embryos about 24 hr after fertilization, which corresponds to 24 hr before the first detectable immunoglobulin.
Chromosome segregation is frequently associated with the expression of recessive mutations in mouse cells.
Authors: Eves E M , Farber R A
Published: May 2006

The genes coding for adenosine kinase (ADK; ATP:adenosine 5'-phosphotransferase, EC 2.7.1.20) and esterase-10 (ES-10; carboxylesterase, carboxylic-ester hydrolase, EC 3.1.1.1) are both located on chromosome 14 in the mouse. The near-diploid mouse cell line CAK is heterozygous for two electrophoretic variants of ES-10. Recessive Adk- mutants of CAK have been isolated and analyzed for Es-10 phenotype and karyotypic abnormalities. Two classes of mutants were found with approximatley equal frequencies: those that remained heterozygous in the expression of Es-10 and those that expressed only one Es-10 allele. Of the mutants that lacked one form of ES-10, approximately half were missing most or all of one copy of chromosome 14; the other contained two copies of 14, frequently in the form of an isochromosome. There were no abnormalities of this chromosome found among the mutants that were Es-10 heterozygotes. These results suggest that the expression of an autosomal recessive mutation in near-diploid mouse cells is frequently associated with events that result in the segregation of a physically linked marker and part or all of a chromosome.
Effect of chronologic age on induction of cystathionine synthase, uroporphyrinogen I synthase, and glucose-6-phosphate dehydrogenase activities in lymphocytes.
Authors: Gartler S M , Hornung S K , Motulsky A G
Published: May 2006

The activities of cystathionine synthase [L-serine hydro-lyase (adding homocysteine), EC 4.2.1.22], uroporphyrinogen I synthase [porphobilinogen ammonia-lyase (polymerizing), EC 4.3.1.8], and glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate:NADP+ 1-oxidoreductase, EC 1.1.1.49) have been measured in phytohemagglutinin-stimulated lymphocytes of young and old human subjects. A significant decrease in activity with age was observed for cystathionine synthase and uroporphyrinogen I synthase but not for glucose-6-phosphate dehydrogenase. These changes could not be related to declining phytohemagglutinin response with aging. Age-related decreases in activity of some enzymes may be relevant for an understanding of the biology of aging. False assignment of heterozygosity, and even homozygosity, for certain genetic disorders, such as homocystinuria, may result when low enzyme levels are detected in the lymphocytes of older people.