bluuebunny/crossref_metadata_2025 huggingface dataset:
Proteins related to the mouse L-cell major heat shock protein are synthesized in the absence of heat shock gene expression.
Authors: Lowe D G , Moran L A
Published: May 2006

Heat shock of mouse L cells induces the synthesis of two polypeptides of Mrs 68,000 and 89,000. Using a fragment of a cloned gene encoding the Drosophila melanogaster Mr 70,000 heat shock protein (hsp70), we have shown that this protein has been highly conserved during eukaryotic evolution. We extended this observation by probing at low stringency for the expression in mouse L cells of RNA homologous to the Drosophila hsp70 gene. In addition to the RNA encoding the inducible Mr 68,000 heat shock protein (hsp68), there are mouse mRNAs encoding proteins of Mrs 70,000 and 74,000 that are homologous to the Drosophila hsp70 gene. The Mrs 70,000 and 74,000 proteins and their mRNAs are abundant components of unstressed mouse L cells. These constituitively expressed proteins are unique polypeptides in contrast to the several isoelectric point variants of the inducible hsp68. We do not detect hsp68 or its mRNA in unstressed L cells. In addition to the mRNAs corresponding to hsp68 and the Mrs 74,000 and 70,000 proteins, we detect a fourth RNA homologous to the Drosophila hsp70 gene but whose protein product has not been identified. Our results suggest that the hsp68 gene of mouse L cells is a member of a multigene family and that the individual family members are distinguishable by their degree of similarity but show differences in the regulation of their expression.
Occurrence of cell division is not exponentially distributed: differences in the generation times of sister cells can be derived from the theory of survival of populations.
Authors: Murphy J S , Landsberger F R , Kikuchi T , Tamm I
Published: May 2006

The Eyring-Stover survival theory has been applied to the kinetics of the distribution of intermitotic intervals of mammalian cells and by inference to the transition from the G1 phase into DNA synthesis (S phase). The theory faithfully fits experimental data acquired by time-lapse cinemicrography of cloned HeLa cells in tissue culture and also suggests the existence of a labile initiator substance which mediates the G1-S phase transition. This theory provides an alternative to the transition probability model proposed by Smith and Martin [Smith J. A. & Martin, L. (1973) Proc. Natl. Acad. Sci. USA 70, 1263-1267; see also Shields, R. & Smith, J. A. (1977) J. Cell Physiol. 91, 345-355 and Brooks, R. F., Bennett, D. C. & Smith, J. A. (1980) Cell 19, 493-504].
An unusual 5' splice sequence is efficiently utilized in vivo.
Authors: Fischer H D , Dodgson J B , Hughes S , Engel J D
Published: May 2006

The minor adult chicken alpha-globin gene (alpha D) has an intron splicing sequence at the 5' end of the second intron that begins with the dinucleotide G-C rather than the usual G-T. To understand what role this splice sequence plays in the processing and maturation of nuclear RNA to cytoplasmic RNA, we have analyzed the intron processing of the alpha D-globin transcript in both heterologous (monkey) and homologous (chicken) cells using simian virus 40 and retrovirus vectors, respectively. In both cell types, both introns of the alpha D-globin gene are efficiently and precisely removed.
Genetic mapping of the human X chromosome by using restriction fragment length polymorphisms.
Authors: Drayna D , Davies K , Hartley D , Mandel J L , Camerino G , Williamson R , White R
Published: May 2006

Using a human X chromosome-specific DNA library, we have found arbitrary single-copy DNA sequences that reveal useful restriction fragment length polymorphisms. The inheritance of these and other available polymorphic DNA markers has been studied in a series of unrelated three-generation families with large sibships. These families reveal parental phase and allow determination of recombination frequencies by counting recombinant and nonrecombinant chromosomes. The resulting genetic map indicates that the minimal distance from Xp22 to Xqter is 215 recombination units. The spacing of the marker loci is such that the majority of the loci on the X chromosome, including disease loci, will lie within 20 centimorgans of at least one of these loci.
Evolutionary principles for polynomial models of frequency-dependent selection
Authors: Curtsinger James W.
Published: May 2006

A one-locus two-allele deterministic model of frequency-dependent selection is analyzed, where genotypic fitnesses [

w
i

(
q
)] are assumed to be
n
th-degree polynomial functions of allelic frequency (
q
). The model encompasses many modes of selection, including intraspecies competitive interaction, brood selection, meiotic drive, cyclical selection, and mixed models. Allelic frequencies converge monotonically to locally stable equilibria provided that ǀ

dw
i

(
q
)/
dq
ǀ is not large. There exists a function
T
(
q
) that is nondecreasing and locally maximized at locally stable equilibria. The rate of change of
T
(
q
) per generation is approximately equal to the additive genetic variance in fitness.
T
(
q
) is a simple function of the average effect of an allelic substitution and is closely related to Wright's “fitness function.” These results define “evolutionary landscapes” for some complex selection processes and enlarge the scope of the classical methods embodied in Wright's “mean fitness principle” and Fisher's “fundamental theorem.”
Second antibody clearance of radiolabeled antibody in cancer radioimmunodetection.
Authors: Sharkey R M , Primus F J , Goldenberg D M
Published: May 2006

The imaging of tumors using radiolabeled antibodies previously has required the implementation of computer-assisted subtraction techniques to reduce background radioactivity. A decrease in radioactivity in the blood of hamsters bearing human colonic tumor xenografts has been achieved by administering a second antibody directed against a radiolabeled primary antibody to carcinoembryonic antigen (CEA). This method was found to reduce the level of blood radioactivity by a factor of 4 within 2 hr after injection of the second antibody and to enhance tumor/nontumor ratios within 24 hr. Unlike liposomally entrapped second antibody, the primary anti-CEA antibody did not show increased accretion of radioactivity in the liver, spleen, or other major organs. These results suggest that administration of a second antibody alone may improve tumor imaging with a radiolabeled antitumor antibody.
Sendai virus-specific T-cell clones: induction of cytolytic T cells by an anti-idiotypic antibody directed against a helper T-cell clone.
Authors: Ertl H C , Finberg R W
Published: May 2006

We used a monoclonal anti-idiotypic antibody that is directed against a Sendai virus-specific helper T-cell clone to induce an anti-viral immune response in vivo. Splenocytes primed with the anti-idiotypic antibody mediated an antigen-specific cytolytic response. Preimmunization of mice with the anti-idiotypic antibody resulted in protection against a subsequent lethal infection with Sendai virus.
Induction of immunoglobulin allotypic suppression in the rabbit: a cellular approach.
Authors: Benaroch P , Bordenave G
Published: May 2006

Adult rabbits were sensitized against rabbit immunoglobulin allotypic specificities of the a and b series by means of two injections of their own lymphocytes coated with the appropriate IgG. The splenic lymphocytes from these sensitized rabbits were injected, 24 hr after birth, into newborns that had inherited from their father the allotypic specificities susceptible to recognition by the sensitized lymphocytes. A significant percentage (40%) of the young rabbits subjected to this treatment developed a total suppression of expression of these specificities with the well-known compensatory effect due to an increased expression of the corresponding allele. We have observed that the T Julius subset of the sensitized splenic lymphocytes was responsible for the induction of this suppression that was established without discernible intervention of anti-allotype antibodies. In one instance we observed that the expression of the allotypic specificities transmitted by the father, although established at 5 weeks of age, gradually declined and totally disappeared at 13 weeks of age.
Thymosin increases production of T-cell growth factor by normal human peripheral blood lymphocytes.
Authors: Zatz M M , Oliver J , Samuels C , Skotnicki A B , Sztein M B , Goldstein A L
Published: May 2006

The in vitro incubation of phytohemagglutinin-stimulated peripheral blood lymphocytes with thymosin results in a marked and reproducible increase in production of T-cell growth factor, which is dose dependent and most pronounced in the first 24 hr of culture. Incubation of lymphocytes with thymosin alone failed to induce any production of T-cell growth factor. The biological activity of thymosin fraction 5 cannot be attributed to the activity of thymosin alpha 1, one of the well-characterized peptide components of fraction 5. These data provide the basis for (i) a potential mechanism for the in vivo immunorestorative effects of thymosin in primary and secondary immunodeficiencies and (ii) identification of an additional, but as yet undefined, immunoregulatory component of thymosin fraction 5.
Multiple opioid receptors in endotoxic shock: evidence for delta involvement and mu-delta interactions in vivo.
Authors: D'Amato R , Holaday J W
Published: May 2006

The use of selective delta and mu opioid antagonists has provided evidence that delta opioid receptors within the brain mediate the endogenous opioid component of endotoxic shock hypotension. The selectivity of these delta and mu antagonists was demonstrated by their differing effects upon morphine analgesia and endotoxic hypotension. The mu antagonist beta-funaltrexamine, at doses that antagonized morphine analgesia, failed to alter shock, whereas the delta antagonist M 154,129: [N,N-bisallyl-Tyr-Gly-Gly-psi-(CH2S)-Phe-Leu-OH] (ICI) reversed shock at doses that failed to block morphine analgesia. Therefore, selective delta antagonists may have therapeutic value in reversing circulatory shock without altering the analgesic actions of endogenous or exogenous opioids. Additional data revealed that prior occupancy of mu binding sites by irreversible opioid antagonists may allosterically attenuate the actions of antagonists with selectivity for delta binding sites. For endogenous opioid systems, this observation provides an opportunity to link in vivo physiological responses with receptor-level biochemical interactions.
Reexamination of the evidence for paramagnetism in oxy- and carbonmonoxyhemoglobins.
Authors: Cerdonio M , Morante S , Torresani D , Vitale S , DeYoung A , Noble R W
Published: May 2006

Experiments have been carried out in an attempt to confirm previous reports of paramagnetism in the oxy- and carbonmonoxy derivatives of human and carp hemoglobin. When care is taken to ensure complete saturation of the hemoglobins with ligand and the diamagnetic contributions of all of the buffers are carefully evaluated, these hemoglobin derivatives are found to have the same gram susceptibilities as exhibited by a set of metal free proteins, suggesting that they are fully diamagnetic.
Rapid processing of the carboxyl terminus of a trypanosome variant surface glycoprotein.
Authors: Bangs J D , Hereld D , Krakow J L , Hart G W , Englund P T
Published: May 2006

The variant surface glycoprotein of the parasite Trypanosoma brucei contains a glycolipid of unknown structure covalently attached to its COOH terminus. We have shown, by using metabolic labeling with [35S]methionine or [3H]myristic acid, precipitation with specific antibodies, and NaDodSO4/polyacrylamide gel electrophoresis, that this glycolipid is attached to the variant surface glycoprotein polypeptide within 1 min after its translation.
Developmentally regulated expression of the bean β-phaseolin gene in tobacco seed
Authors: Sengupta-Gopalan Champa , Reichert Nancy A. , Barker Richard F. , Hall Timothy C. , Kemp John D.
Published: May 2006

Recombinant phage λ177.4 contains a gene for β phaseolin, a major storage glycoprotein of French bean seed. A 3.8-kilobase
Bgl
II-
Bam
HI fragment containing the entire 1700-base-pair coding region, together with 863 base pairs of 5′ and 1226 base pairs of 3′ flanking sequence, was inserted into the A66 Ti plasmid of
Agrobacterium tumefaciens
and used to transform tobacco. The level of phaseolin in the seeds of plants regenerated from cloned tissue was 1000-fold higher than in other tissues. The molecular weight of the phaseolin RNA transcript in tobacco seeds was identical to that found in bean seeds. The phaseolin protein in tobacco seed was glycosylated and appeared to undergo removal of the signal peptide. However, a large proportion of the phaseolin was cleaved into discrete peptides. These same peptides were formed as phaseolin was degraded during tobacco seed germination. The phaseolin gene appeared to be inserted as a single copy, and the proportion of phaseolin per genome copy in tobacco seeds (up to 3% of the total embryo proteins) resembled that in the bean seeds (40% of total seed protein, expressed from about 14 copies per diploid genome). Furthermore, the transplanted gene was turned on during tobacco seed development, and its protein product, phaseolin, was localized in the embryonic tissues. Finally, the phaseolin gene was inherited as a Mendelian dominant trait in tobacco.
Chromosomal assignments of the genes coding for human types II, III, and IV collagen: a dispersed gene family.
Authors: Solomon E , Hiorns L R , Spurr N , Kurkinen M , Barlow D , Hogan B L , Dalgleish R
Published: May 2006

The human type II collagen gene, COL2A1, has been assigned to chromosome 12, the type III gene, COL3A1, to chromosome 2, and one of the type IV genes, COL4A1, to chromosome 13. These assignments were made by using cloned genes as probes on Southern blots of DNA from a panel of mouse/human somatic cell hybrids. The two genes of type I collagen, COL1A1 and COL2A1, have been mapped previously to chromosomes 17 and 7, respectively. This family of conserved genes seems therefore to be dispersed throughout the genome.
Regulation of expression from the glnA promoter of Bacillus subtilis requires the glnA gene product.
Authors: Schreier H J , Fisher S H , Sonenshein A L
Published: May 2006

Expression of the cloned glnA gene [coding for glutamine synthetase (EC 6.3.1.2)] of Bacillus subtilis was 10-fold higher in an Escherichia coli strain grown under nitrogen-limiting conditions than in the same strain under nitrogen-excess conditions. Mutations in the E. coli glnA, glnB, glnD, glnE, glnF, glnG, and glnL genes had no effect on the observed regulation. To test whether sequences within the B. subtilis DNA (3.2 kilobase pairs) were responsible for the observed regulation, a plasmid carrying a transcriptional fusion of the B. subtilis glnA promoter with E. coli lacZ was constructed. beta-Galactosidase levels coded for by this plasmid were found to be negatively regulated in trans by a plasmid carrying the entire B. subtilis glnA gene. Analysis of various deletion plasmids showed that the 1.4-kilobase-pair region encoding glutamine synthetase was necessary for the observed regulation of beta-galactosidase. Plasmids coding for 67% or more of the glutamine synthetase polypeptide gave at least partial repression, but a plasmid carrying 30% of the structural gene, as well as a plasmid carrying a deletion internal to glnA, gave no repression. DNA downstream from glnA (to within 130 base pairs of the end of the gene) was not required for the observed regulation. These results suggest that the glnA gene of B. subtilis is autoregulated, supporting the model for glnA control proposed by Dean et al. [Dean, D. R., Hoch, J. A. & Aronson, A. I. (1977) J. Bacteriol. 131, 981-987].
Incomplete X chromosome dosage compensation in chorionic villi of human placenta.
Authors: Migeon B R , Wolf S F , Axelman J , Kaslow D C , Schmidt M
Published: May 2006

Studies of glucose-6-phosphate dehydrogenase (G6PD) in heterozygous cells from chorionic villi of five fetal and one newborn placenta show that the locus on the allocyclic X is expressed in many cells of this trophectoderm derivative. Heterodimers were present in clonal populations of cells with normal diploid karyotype and a late replicating X chromosome. The expression of the two X chromosomes was unequal, based on ratios of homodimers and heterodimers in clones. Studies of DNA, digested with Hpa II and probed with cloned genomic G6PD sequences, indicate that expression of the locus in chorionic villi is associated with hypomethylation of 3' CpG clusters. These findings suggest that dosage compensation, at least at the G6PD locus, has not been well established or maintained (or both) in placental tissue. Furthermore, the active X chromosome in these human cells of trophoblastic origin can be either the paternal or maternal one; therefore, paternal X inactivation in extraembryonic lineages is not an essential feature of mammalian X dosage compensation.
DNA sequence and characterization of human class II major histocompatibility complex beta chains from the DR1 haplotype.
Authors: Bell J I , Estess P , St John T , Saiki R , Watling D L , Erlich H A , McDevitt H O
Published: May 2006

Two HLA class II beta-chain clones from a cell line homozygous for the DR1 haplotype have been characterized and sequenced. They represent a DR beta chain (2918.4) and a DQ beta chain (2918.8). Clone 2918.4 has been used to select mRNA from a lymphoblastoid cell line, and this was injected into Xenopus oocytes with mRNA selected with a DR alpha chain. The translation products were immunoprecipitated with a beta-chain-specific monoclonal antibody and electrophoresed on two-dimensional gels. This revealed positive signals in the positions predicted for beta and alpha chains. Sequence comparisons of 2918.4 with previously published DR beta-chain sequences confirm the presence of two regions of variability in the membrane distal domain. Analysis of the sequence of 2918.8 identified it as a DQ beta chain identical to one previously published from a DR3,w6 cell line. We speculate, therefore, that the DQ beta sequence represents the DQ1 specificity shared by the DR1 and DRw6 haplotypes.
Toward an analogue of alcoholism in mice: criteria for recognition of pharmacologically motivated drinking.
Authors: Dole V P , Ho A , Gentry R T
Published: May 2006

Two criteria of alcoholic drinking behavior--inelasticity of demand and dissociation of intake from normal eating and drinking--are illustrated by study of alcohol-preferring C57BL/6J mice. Although these mice drink enough to become intoxicated for brief periods each night, they do not meet the more rigorous criteria for pharmacologically motivated drinking. Their intake of alcohol was dramatically decreased when they were offered diets augmented with sugar or Crisco, and the temporal pattern of drinking was correlated with the intake of food. Thus, their motivation for drinking alcohol is related to nutrition and is not drug-seeking comparable to that of human alcoholics. Since the tests are simple and decisive, it might be useful to apply them to all putative models of alcoholism.
Polymorphism of normal factor IX detected by mouse monoclonal antibodies.
Authors: Wallmark A , Ljung R , Nilsson I M , Holmberg L , Hedner U , Lindvall M , Sjögren H O
Published: May 2006

Hemophilia B is an X-chromosomal recessive disease due to deficiency of coagulation factor IX. Three monoclonal antibodies against factor IX were prepared and used to develop immunoradiometric assays (IRMAs) of factor IX antigen (IX-Ag). IX-Ag was measured in 65 normal individuals with one IRMA based on polyclonal anti-IX antibodies and two IRMAs based on three monoclonal anti-IX antibodies. One of the monoclonal antibodies differed in specificity since it neutralized less than 50% of the clotting activity of factor IX (IX-C), whereas the other two monoclonal antibodies neutralized 80-95%. When the former antibody was used as the solid phase in IRMA, two groups of normal individuals were distinguished: group A with measurable IX-Ag, and group B without demonstrable IX-Ag. There were no differences between the groups either in IX-C or in IX-Ag measured with polyclonal antibodies. A subgroup comprising only women could be distinguished in group A, in whom intermediate IX-Ag concentrations were found. Family studies showed the group B variant of normal factor IX to be transmitted according to the pattern of X-linked recessive inheritance. The allelic frequency of group A was 0.66, and that of group B was 0.34.
Insulin-related genes expressed in human placenta from normal and diabetic pregnancies.
Authors: Liu K S , Wang C Y , Mills N , Gyves M , Ilan J
Published: May 2006

Rapid growth of human fetal tissues requires insulin or insulin-like growth factors. A high rate of human fetal growth occurs between implantation and about 14 weeks of gestation. Fetal pancreatic insulin secretion begins much later. Since maternal insulin does not cross the blood/placental barrier, other sources of insulin or insulin-like growth factors may be provided for fetal development. We report here that placental polyadenylylated RNAs from the first and third trimester of normal pregnancy as well as from term pregnancies of diabetic mothers hybridize to a 32P-labeled cloned cDNA of an insulin-related sequence expressed in fetal pancreas. Moreover, placentas from diabetic women express much more of these sequences. These results suggest that insulin-related genes are expressed in placental tissue during fetal development and may be a source of growth-promoting hormones for the human fetus. Fetuses developing in diabetic women receive a large influx of glucose. This in turn may stimulate the expression of insulin-related sequences, which may result in higher utilization of glucose, thus bringing about the macrosomia and high incidence of malformation and still-births known to result from pregnancies in diabetics.
Dispersion of growing axons within the optic nerve of the embryonic monkey.
Authors: Williams R W , Rakic P
Published: May 2006

To determine whether individual optic fibers grow along constant sets of neighboring fibers, a group of 160 axons and 25 axonal growth cones were traced through a set of 500 serial electron micrographs of an optic nerve taken from a 39-day-old monkey embryo (Macaca mulatta). In single transverse sections, growth cones contact an average of 7.9 fibers, whereas axons contact 5.3 other fibers. The particular set of fibers in contact with one another changed rapidly, and, on average, growth cones and axons lost half of their original neighbors over a distance of only 8-10 micron. Between the first and last sections of the series, 92% of all initial contacts were lost. Individual axons moved freely between fiber fascicles, and the distance separating initial neighbors increased progressively. Most remarkably, the sets of fibers touched by the tips and the shanks of growth cones had no common neighbors in 17 out of 25 cases. These results demonstrate that, in primates, fibers in the optic nerve do not retain a particular set of immediate neighbors during their outgrowth.
Synaptic transmission from rods to bipolar cells in the tiger salamander retina.
Authors: Wu S M
Published: May 2006

Synaptic transmission between rods and depolarizing bipolar cells (DBC) was studied by using simultaneous recording techniques in the living retinal slice preparation. Current injection into the rod elicited a sign-inverting, sustained voltage change in the DBC. Voltage "tails" after the termination of a bright flash were observed in dark-adapted rods and DBC but not in cones. These simultaneously recorded voltage tails were used to isolate the rod input from the cone input and to study the input-output relation of the rod-DBC synapse. Within the voltage range between 0 and -10 mV from the rod dark potential (-39 +/- 1.2 mV), the input-output relation of the rod-DBC was approximately linear, with an estimated gain of about 3.7.
Initiation of DNA replication on single-stranded DNA templates catalyzed by purified replication proteins of bacteriophage lambda and Escherichia coli.
Authors: LeBowitz J H , Zylicz M , Georgopoulos C , McMacken R
Published: May 2006

Initiation of bacteriophage lambda DNA replication at the chromosomal origin depends on the lambda O and P replication proteins. These two viral initiators, together with an Escherichia coli protein fraction, promote the replication in vitro of single-stranded circular DNA chromosomes such as that of bacteriophage M13. This nonspecific strand initiation reaction, which we have termed the "lambda single-strand replication reaction," has now been established with eight purified proteins, each of which is also required for replication of the phage lambda chromosome in vivo. An early rate-limiting step in the overall reaction is the ATP-dependent assembly of an activated nucleoprotein prepriming complex. In this step the lambda O and P initiators cooperate with the E. coli dnaJ and dnaK proteins to transfer the bacterial dnaB protein onto M13 DNA that is coated with the single-stranded DNA-binding protein. Multiple RNA primers are synthesized on each DNA circle when isolated prepriming complex is incubated with primase and rNTPs. In the complete system, DNA polymerase III holoenzyme extends the first primer synthesized into full-length complementary strands. Because the properties of this system are closely analogous to those found for the replication of phi X174 viral DNA by E. coli proteins, we infer that a mobile prepriming or priming complex (primosome) operates in the lambda single-strand replication reaction.
Microtubule configurations during fertilization, mitosis, and early development in the mouse and the requirement for egg microtubule-mediated motility during mammalian fertilization.
Authors: Schatten G , Simerly C , Schatten H
Published: May 2006

Microtubules forming within the mouse egg during fertilization are required for the movements leading to the union of the sperm and egg nuclei (male and female pronuclei, respectively). In the unfertilized oocyte, microtubules are predominantly found in the arrested meiotic spindle. At the time for sperm incorporation, a dozen cytoplasmic asters assemble, often associated with the pronuclei. As the pronuclei move to the egg center, these asters enlarge into a dense array. At the end of first interphase, the dense array disassembles and is replaced by sheaths of microtubules surrounding the adjacent pronuclei. Syngamy (pronuclear fusion) is not observed; rather the adjacent paternal and maternal chromosome sets first meet at metaphase. The mitotic apparatus emerges from these perinuclear microtubules and is barrel-shaped and anastral, reminiscent of plant cell spindles; the sperm centriole does not nucleate mitotic microtubules. After cleavage, monasters extend from each blastomere nucleus. The second division mitotic spindles also have broad poles, though by third and later divisions the spindles are typical for higher animals, with narrow mitotic poles and fusiform shapes. Colcemid, griseofulvin, and nocodazole inhibit the microtubule formation and prevent the movements leading to pronuclear union; the meiotic spindle is disassembled, and the maternal chromosomes are scattered throughout the oocyte cortex. These results indicate that microtubules forming within fertilized mouse oocytes are required for the union of the sperm and egg nuclei and raise questions about the paternal inheritance of centrioles in mammals.
Mapping of the C3d receptor (CR2)-binding site and a neoantigenic site in the C3d domain of the third component of complement.
Authors: Lambris J D , Ganu V S , Hirani S , Müller-Eberhard H J
Published: May 2006

The C3d domain of C3 contains the site that binds to the C3d receptor (CR2) which is expressed on B lymphocytes. It also contains a neoantigenic determinant that is recognized by monoclonal antibody (mAb) 130 and is expressed when C3b is cleaved to iC3b and subsequently to C3dg or C3d. mAb 130 inhibits the binding of C3d to CR2. In this study, the locations of the CR2-binding site and of the neoantigen recognized by mAb 130 within the C3d domain were investigated. Treatment of human C3d with CNBr generated two major fragments with Mrs of 12,500 and 8600. Binding studies showed that only the Mr 8600 fragment was capable of binding to both CR2 and mAb 130. Amino-terminal sequence analysis of the Mr 8600 fragment and comparison with the amino acid sequence derived from human C3 cDNA [de Bruijn, M. H. L. & Fey, G. H. (1985) Proc. Natl. Acad. Sci. USA 82, 708-712] placed it between residues 1199 and 1274 of the C3 sequence. Several peptides were synthesized according to the derived C3 sequence of amino acid residues 1209-1236. Based on their differential binding to CR2 and mAb 130, we localized the CR2-binding site and mAb 130 neoantigenic site, respectively, to residues 1227-1232 and 1217-1232 of the C3 sequence.
Failure to demonstrate pluripotential hemopoietic stem cells in mouse brains.
Authors: Hoogerbrugge P M , Wagemaker G , van Bekkum D W
Published: May 2006

Hemopoietic stem cells as defined by the capacity to produce spleen colonies in lethally irradiated recipients were reported by P. F. Bartlett [(1982) Proc. Natl. Acad. Sci. USA 79, 2722-2725] to be present in high frequencies in mouse brain. He also reported similar numbers of colony-forming units, spleen (CFU-s), in the brains of Wf/Wf mice, the bone marrow of which lacks detectable spleen colony-forming cells. To verify these observations, single cell suspensions were produced from murine brains by incubation with trypsin and DNase, followed by removal of myelin by Percoll gradient centrifugation. Two to 13 CFU-s were detected per brain. This low number suggested contamination of the brains by either blood or bone marrow leaking from the skull bones during dissection. When the isolated, intact brains were washed carefully in balanced salt solution, the recovered number of CFU-s decreased to 0.1-0.4 per brain. No CFU-s could be detected in the brains of W/Wv mice. It is concluded that the CFU-s observed by Bartlett in preparations of mouse brain did not originate from the brain tissue.
Identification of proliferin mRNA and protein in mouse placenta.
Authors: Linzer D I , Lee S J , Ogren L , Talamantes F , Nathans D
Published: May 2006

Proliferin is a recently described, prolactin-related protein whose mRNA appears in several murine cell lines during active growth. We have surveyed a number of mouse organs or tissues for the presence of mRNAs that hybridize to cloned proliferin cDNA. Of the tissues tested, only the placenta yielded proliferin-related mRNA. This placental RNA is about 1 kilobase in length, increases sharply between days 8 and 10 of pregnancy, and then gradually declines through day 18. It is more abundant in RNA extracted from the fetal, compared to the maternal, part of the placenta. From a cDNA plasmid library prepared from poly(A)+ placental RNA, two types of proliferin-related clones were isolated, differing in intensity of hybridization to proliferin cDNA. By nucleotide sequence analysis, a strongly hybridizing clone was found to be nearly identical to the proliferin cDNA clone isolated from a library prepared from mRNA of a growing mouse fibroblastic cell line. Using an antiserum prepared against a synthetic proliferin fusion protein, we show that proliferin is secreted as a glycoprotein by minced placental tissue and that it differs from mouse placental lactogen. We conclude that proliferin is a placental hormone that is synthesized in certain mouse cell lines during active growth. Its function during pregnancy and during the growth of cultured cells is presently unknown.
Induction of ornithine decarboxylase activity by insulin and growth factors is mediated by amino acids.
Authors: Rinehart C A , Canellakis E S
Published: May 2006

The polypeptide growth factors, nerve growth factor, epidermal growth factor, and platelet-derived growth factor, as well as insulin do not induce ornithine decarboxylase (L-ornithine carboxy-lyase, EC 4.1.1.17) unless a minimal concentration of an ornithine decarboxylase-inducing amino acid, such as asparagine, is present in the medium. The effects of the growth factors were studied in appropriately responsive cell lines: pheochromocytoma (PC12) cells for nerve and epidermal growth factors, fibroblasts (NIH 3T3) for platelet-derived growth factor, and fibroblasts and hepatoma (KRC-7) cells for insulin. The nonmetabolizable amino acid analog alpha-aminoisobutyric acid can replace asparagine, indicating that the covalent modification of the inducing amino acid is not necessary for the induction of ornithine decarboxylase by these growth factors. For the same intracellular concentration of the inducing amino acid, the presence of the growth factors induces higher levels of ornithine decarboxylase. The evidence indicates that these growth factors do not induce ornithine decarboxylase by raising the intracellular concentration of amino acids but rather act synergistically with the inducing amino acid. Evidence is provided that the induction of polyamine-dependent growth by these growth factors is mediated by amino acids. The relationship of these results to the A and N amino acid transport systems and to the Na+ influxes in relation to growth is discussed.
Differential expression of intermediate filament proteins distinguishes classic from variant small-cell lung cancer cell lines.
Authors: Broers J L , Carney D N , de Ley L , Vooijs G P , Ramaekers F C
Published: May 2006

The expression of intermediate filament proteins in classic and variant-type small-cell lung carcinoma (SCLC) cell lines was studied using immunocytochemical techniques, two-dimensional gel electrophoresis and immunoblotting assays. Classic SCLC cell lines contain cytokeratin proteins but no neurofilaments. In contrast, variant cell lines do not contain detectable amounts of cytokeratins but partly express neurofilaments and vimentin. These results explain apparent discrepancies on the intermediate filament content of SCLC described in the recent literature. The application of antibodies to fresh biopsy specimens of SCLC may in the future allow the identification of the variant type of cells in clinical SCLC specimens and may have a major impact on therapeutic strategy and prognosis in these patients.
Close linkage of alpha and beta interferons and infrequent duplication of beta interferon in humans.
Authors: Ohlsson M , Feder J , Cavalli-Sforza L L , von Gabain A
Published: May 2006

Five restriction fragment length polymorphisms in the human alpha/beta interferon (IFN-alpha/beta) gene region were identified, three with an IFN-alpha probe and two with an IFN-beta probe. Heterozygosities are 74% for IFN-alpha, 57% for IFN-beta, and 87% jointly, making IFN-alpha/beta genes excellent markers for the short arm of chromosome 9. The pedigrees of about 25 families of Caucasian background were studied. Segregation analysis disclosed the occurrence of 12 of 32 possible haplotypes. No recombinant was found between IFN-alpha and -beta genetic markers; linkage disequilibrium within the IFN-alpha markers is of a similar order of magnitude as that between the IFN-alpha and -beta markers. The IFN-alpha and -beta genes might cluster within several hundred kilobases. In two parents, the IFN-beta gene is duplicated; the duplications segregate regularly. They are of independent, probably recent, origin. Therefore, some degree of multiplicity might even be found for IFN-beta, at least in some individuals.
Evidence for active synapse formation or altered postsynaptic metabolism in visual cortex of rats reared in complex environments.
Authors: Greenough W T , Hwang H M , Gorman C
Published: May 2006

Animals placed in complex environments develop greater numbers of visual cortex synapses per neuron than animals housed in standard cages. Increased numbers of synapses could theoretically arise from (i) active formation of new synapses, or (ii) selective stabilization of constitutively produced synapses. The postsynaptic location of polyribosomal aggregates appears to be an indicator of newly forming synapses. In developmental synaptogenesis and adult reactive (to injury) synaptogenesis, polyribosomes are more frequently found at spine synapses and are more likely to appear in the spine head and stem. In the visual cortex of rats from complex environments, there was a greater frequency of spine synapses associated with polyribosomes, relative to rats from individual or group cages. Furthermore, a greater percentage of these spines had polyribosomes in the head and stem region. This suggests that synapses in this region may be actively induced by neural activity arising from the complex environment experience.
Characterization of monoclonal antibodies against Chlamydomonas flagellar dyneins by high-resolution protein blotting.
Authors: King S M , Otter T , Witman G B
Published: May 2006

Monoclonal antibodies that recognize individual polypeptides of the outer arm dyneins of Chlamydomonas flagella were obtained and used to study the structural relationships between the various polypeptides. Immunoblot analysis showed that the gamma heavy chain of 12S dynein and the alpha and beta heavy chains and Mr 69,000 intermediate chain of 18S dynein each contain immunoreactive sites not found in the other dynein chains or in any other axonemal protein. We also used these antibodies to investigate possible structural similarities between dynein polypeptides from Chlamydomonas and phylogenetically distant species. No crossreactivity was observed with antibodies against either the alpha, beta, or gamma heavy chains, demonstrating that each Chlamydomonas heavy chain has structural features distinct from those present in dyneins from the other species tested. However, one antibody against the Mr 69,000 polypeptide recognized an intermediate chain (Mr 76,000) of latent-activity dynein-1 from the sea urchin Tripneustes gratilla. This result provides further evidence that 18S dynein and latent-activity dynein-1 are related. In the course of the above studies, we modified existing procedures to achieve efficient transfer of high molecular weight proteins from NaDodSO4/polyacrylamide gels to nitrocellulose sheets, and to detect small quantities of protein on nitrocellulose. Our modified procedure for staining total protein on nitrocellulose is rapid, inexpensive, and as sensitive as silver-staining of polyacrylamide gels. These methods should be useful to investigators working with small amounts of protein or requiring resolution of closely migrating polypeptides after transfer to nitrocellulose.
Double recombination of a single immunoglobulin kappa-chain allele: implications for the mechanism of rearrangement.
Authors: Feddersen R M , Van Ness B G
Published: May 2006

DNA fragments containing immunoglobulin kappa-chain sequences from two different plasmacytomas (PC 3609 and PC 7043) were found by blot-hybridization studies to be dissociated from germ-line sequences on both the 3' and 5' ends. These fragments were cloned, sequenced, and found to contain the structural features of a product of two recombination events. Each contained a variable (V kappa) gene segment recombined with a joining (J kappa) gene segment followed by the characteristic kappa light chain V-J reciprocal structure, a 5' J kappa flanking sequence joined to a 3' V kappa flanking sequence. These segments of DNA represent double recombination products (DRPs) of the same kappa-chain allele. The DRP from PC 3609 contains a normal V-J1 recombination, while the DRP from PC 7043 contains an aberrant V-J2 recombination, resulting in a frameshift. The reciprocal structure in the PC 3609 DRP is the result of a V-J2 recombination; the reciprocal structure in the DRP of PC 7043 is the result of a V-J3 recombination and appears to have been derived directly from the productive kappa-chain gene recombination in that plasmacytoma. These products demonstrate the capacity of a single kappa light chain immunoglobulin allele to undergo multiple V-J recombinations. Furthermore, the presence of a V-J recombination and its reciprocal product in the same cell is inconsistent with a segregating mechanism, such as sister chromatid exchange, but is consistent with an inversion mechanism.
Transcription factor Sp1 recognizes promoter sequences from the monkey genome that are simian virus 40 promoter.
Authors: Dynan W S , Saffer J D , Lee W S , Tjian R
Published: May 2006

A 440-base-pair fragment of African green monkey genomic DNA shares homology with the transcriptional regulatory region of simian virus 40 (SV40) and has been reported to direct transcription in vivo. We find that two regions within this fragment bind the promoter-specific cellular transcription factor Sp1 and are protected in DNase protection ("footprinting") experiments. As in SV40, binding occurs in regions containing multiple copies of the sequence GGGCGG. These regions, when fused to the proximal, or "TATA box," element of the herpes simplex virus thymidine kinase promoter, are able to direct Sp1-dependent transcription in vitro. The finding that Sp1 is capable of productive interaction with sequences taken from a cellular promoter supports the idea that Sp1 may play a role in modulating transcription of cellular genes.
Linkage and homology analysis divides the eight genes for the small subunit of petunia ribulose 1,5-bisphosphate carboxylase into three gene families
Authors: Dean Caroline , van den Elzen Peter , Tamaki Stanley , Dunsmuir Pamela , Bedbrook John
Published: May 2006

Twenty-six λ phage clones with homology to coding sequences of the small subunit (SSU) of ribulose 1,5-bisphosphate carboxylase have been isolated from an EMBL3 λ phage bank of
Petunia
(Mitchell) DNA. Restriction mapping of the phage inserts shows that the clones were obtained from five nonoverlapping regions of petunia DNA that carry seven
SSU
genes. Comparison of the
Hin
dIII genomic fragments of petunia DNA with the
Hin
dIII restriction fragments of the isolated phage indicates that petunia nuclear DNA encodes eight
SSU
genes, seven of which are present in the phage clones. Two incomplete genes, which contain only the 3′ end of an
SSU
gene, were also found in the phage clones. We demonstrate that the eight
SSU
genes of petunia can be divided into three gene families based on homology to three petunia cDNA clones. Two gene families contain single
SSU
genes and the third contains six genes, four of which are closely linked within petunia nuclear DNA.
Glycyl-L-glutamine, a precursor, and glycyl-L-glutamic acid, a neurotrophic factor for maintenance of acetylcholinesterase and butyrylcholinesterase in the preganglionically denervated superior cervical ganglion of the cat in vivo.
Authors: Koelle G B , Sanville U J , Wall S J
Published: May 2006

L. W. Haynes and M. E. Smith have reported [(1985) Biochem. Soc. Trans. 13, 174-175] that glycyl-L-glutamine (Gly-Gln) increases the A12 and G4 forms of acetylcholinesterase (AcChoEase) in cultured embryonic rat skeletal muscle. Since Gly-Gln meets the criteria established for the neurotrophic factor (NF) in extracts of central nervous system/sciatic nerves that maintains AcChoEase and butyrylcholinesterase (BtChoEase) in the denervated cat superior cervical ganglion (SCG) in vivo, it was tested by the latter procedure. Solutions of Gly-Gln (10(-7)-10(-3) M) in 0.9% NaCl solution were infused for 24 hr via the right common carotid artery of cats with preganglionically denervated SCG, following ligation of the external carotid and lingual arteries. At 48 hr postdenervation, the AcChoEase and BtChoEase contents of the right SCG were within the range of similarly treated controls infused with 0.9% NaCl solution; the AcChoEase and BtChoEase contents of the left SCG, where the infused solutions arrived by way of a much more circuitous route, were significantly elevated at concentrations of Gly-Gln of 10(-5) M and higher. This suggested that the neurotrophic effect on the left SCG was produced by a metabolite of Gly-Gln. Accordingly, glycine, L-glutamine, and glycyl-L-glutamic acid (Gly-Glu) were then tested. Glycine and L-glutamine were inactive; Gly-Glu, 10(-6)-10(-5) M, exerted a significantly positive neurotrophic effect at both the right and left SCG; at 10(-4) M, the effect was absent. The method employed currently for preparation of extracts of SCG for assay of AcChoEase, BtChoEase, and protein contents (homogenization of scissor-minced ganglia in water) was compared with homogenization in molar NaCl/1% Triton X-100. Values obtained by the former procedure, in comparison with the latter, were 91% +/- 7% for AcChoEase and 83% +/- 7% for BtChoEase, expressed as substrate hydrolyzed per mg of protein per min.
Inducible transcription of the unrearranged kappa constant region locus is a common feature of pre-B cells and does not require DNA or protein synthesis.
Authors: Nelson K J , Kelley D E , Perry R P
Published: May 2006

Transcription of unrearranged kappa constant region (kappa 0) loci is dramatically induced in pre-B cells transformed by the Abelson murine leukemia virus when the cells are exposed to bacterial lipopolysaccharide (LPS). Transcriptional activity, detected both by accumulation of the 8-kilobase kappa 0 RNA product and by nuclear run-on measurements, is evident within a few hours after exposure to LPS and continues to increase over a 24-hr period. During this time, transcription of rearranged mu heavy-chain loci remains at the basal constitutive level. In accord with previous studies of the B-cell lymphoma 70Z/3, this transcriptional activation is accompanied by the appearance of a DNase I-hypersensitive site in the kappa enhancer region but not by any detectable hypomethylation of the locus. Moreover, the present studies demonstrate that induction of kappa transcription can occur in the absence of DNA or protein synthesis. These results have led us to propose a model in which an external signal such as LPS or a functionally equivalent lymphokine may initiate kappa transcription in pre-B cells by modifying or overriding the activity of an enhancer-specific factor.
Isolation of infectious human T-cell leukemia/lymphotropic virus type III (HTLV-III) from patients with acquired immunodeficiency syndrome (AIDS) or AIDS-related complex (ARC) and from healthy carriers: a study of risk groups and tissue sources.
Authors: Salahuddin S Z , Markham P D , Popovic M , Sarngadharan M G , Orndorff S , Fladagar A , Patel A , Gold J , Gallo R C
Published: May 2006

Acquired immunodeficiency syndrome (AIDS) and AIDS-related complex (ARC) are thought to be caused by human T-cell leukemia/lymphotropic virus type III (HTLV-III). Since the fall of 1982, independent isolates of HTLV-III have been obtained in this laboratory, in collaboration with several clinical groups, from 101 AIDS and ARC patients and healthy donors at risk for AIDS. Most isolates were from peripheral blood T lymphocytes established in cell culture, but some were obtained from bone marrow, lymph node, brain tissue, and cell-free plasma and from cells associated with saliva, cerebrospinal fluid, and semen. Virus was isolated from approximately 50% of AIDS patients, 85% of ARC patients, and 30% of healthy individuals at risk for AIDS. The risk groups included homosexuals, promiscuous heterosexuals, i.v. drug users, recipients of blood or blood products, and spouses and offspring of AIDS patients and others at risk for AIDS. A high correlation was seen between persistent levels of serum antibody and the ability to isolate virus from patient or donor leukocytes. Immunologic and nucleic acid analysis demonstrated that the virus isolates were highly related, although substantial diversity was observed in the restriction enzyme cleavage patterns of those studied in detail. Biological analysis of cells from infected patients and donors as well as from normal peripheral blood mononuclear cells exposed to virus in vitro demonstrated that OKT4/Leu3a+ (helper/inducer) lymphocytes were preferentially infected and were subjected to a characteristic cytopathic effect. The availability of multiple isolates of virus from a number of different patients and donors will greatly facilitate the characterization of HTLV-III and the study of possible biological and/or biochemical variants of the virus responsible for the development of AIDS, ARC, and related diseases.