bluuebunny/crossref_metadata_2025 huggingface dataset:
Microtubule-associated proteins (MAPs): a monoclonal antibody to MAP 1 decorates microtubules in vitro but stains stress fibers and not microtubules in vivo.
Authors: Asai D J , Thompson W C , Wilson L , Dresden C F , Schulman H , Purich D L
Published: May 2006

A monoclonal antibody (mAb 7-1.1) was produced against a bovine brain microtubule-associated protein (MAP) preparation that had been separated from tubulin after initial purification by cycles of microtubule assembly and disassembly in vitro. The antibody reacted specifically with two high molecular weight polypeptides of the MAP 1 class, designated MAP 1.1 and MAP 1.2, and also with the surfaces of MAP 1-containing microtubules that had been assembled in vitro. Double immunofluorescence microscopy using mAb 7-1.1 and a well-characterized rabbit anti-tubulin antibody revealed that mAb 7-1.1 stained stress fibers in fixed and permeabilized cultured mammalian cells rather than microtubules. The antibody also stained cell nuclei in a punctate fashion. mAb 7-1.1 is one of a number of monoclonal antibodies that react with presumptive MAP 1 polypeptides. Some of the MAP 1 antibodies have been found to bind specifically to microtubules in fixed and permeabilized cells, while others have been reported to react with nonmicrotubule structures. Our results, together with the results of other investigations, indicate that "MAP 1" may be a family of several high molecular weight polypeptides that adventitiously behave as MAPs by the criterion of in vitro coassembly with tubulin through cycles of polymerization and depolymerization but whose cellular distributions, and perhaps functions, are varied.
Tissue-specific levels of human glucose-6-phosphate dehydrogenase correlate with methylation of specific sites at the 3' end of the gene.
Authors: Battistuzzi G , D'Urso M , Toniolo D , Persico G M , Luzzatto L
Published: May 2006

Glucose-6-phosphate dehydrogenase (G6PD) is a ubiquitous enzyme that supplies the cell with NADPH required for a variety of reductive reactions and biosynthetic processes. Therefore, the gene G6PD, located in mammals on the X chromosome, that specifies G6PD can be regarded as a typical housekeeping gene. We have investigated the expression of human G6PD in eight different fetal and adult tissues by determining the level of enzyme activity, the level of G6PD mRNA, and the methylation pattern of the 3' end of the gene, for which we have nucleic acid probes. By combining sequence information with results of Southern blot analysis of DNA samples digested with the methylation-sensitive restriction enzyme Hpa II, we have identified five specific sites that are unmethylated in all tissues examined, a number of sites that are uniformly methylated, and a number of sites that are sometimes methylated. A subset of Hpa II sites, designated on our restriction map as H37-H55, exhibit positive correlation between degree of methylation, level of mRNA, and level of G6PD activity. A comparison of these methylation patterns with those we previously have observed in the G6PD gene on the inactive X chromosome [Toniolo, D., D'Urso, M., Martini, G., Persico, M.G., Tufano, V., Battistuzzi, G. & Luzzatto, L. (1984) EMBO J. 3, 1987-1995] indicates that different sites are associated with X-inactivation and with the regulation of G6PD on the active X chromosome. We conclude that this housekeeping gene is subject to tissue-specific transcriptional regulation, which in turn correlates with methylation of specific sites located at and near the 3' end of the gene.
The receptor for immunoglobulin E on rat basophilic leukemia cells: effect of ligand binding on receptor expression.
Authors: Furuichi K , Rivera J , Isersky C
Published: May 2006

We have evaluated the effect of ligand binding on expression of the receptor for IgE on rat basophilic leukemia (RBL) cells. RBL cells were grown in the presence or absence of 131I-labeled IgE and sometimes were also surface labeled with 125I. We found that cells grown in the presence of IgE continued to accumulate receptors at the surface and thus the apparent amount of cell-associated IgE continued to increase. The results obtained suggest that, in the presence of IgE, the elimination of the receptor from the surface was halted or slowed significantly (approximately equal to 80%) while insertion into the membrane of previously synthesized receptor continued.
Isolation of a cDNA clone encoding pancreatic polypeptide.
Authors: Takeuchi T , Yamada T
Published: May 2006

We have isolated a cDNA clone encoding pancreatic polypeptide from a cDNA library constructed with RNA from an endocrine neoplasm of the human pancreas. The cDNA was inserted into plasmid pBR322 and the plasmid was cloned in Escherichia coli. Oligonucleotides (sequence in text) specific for the amino acid sequence (sequence in text) of pancreatic polypeptide were used as hybridization probes. The pancreatic polypeptide cDNA isolated was 465 base pairs long and encoded a peptide of 95 amino acids in the coding region. The 36-amino acid sequence of pancreatic polypeptide was flanked by a 29-amino acid putative leader sequence at the amino terminus and a connecting tripeptide (Gly-Lys-Arg) followed by a 27-amino acid peptide at the carboxyl terminus. The first 20 of the amino acids in the carboxyl-terminal heptacosapeptide were identical to the structure of human pancreatic icosapeptide with the single exception of an isoleucine substitution for valine in the 18th position. This alteration results from an A----G substitution in the nucleotide sequence of the cDNA and may represent a genetic variation or a point mutation in the pancreatic polypeptide cDNA.
High glucose concentrations partially release hexokinase from inhibition by glucose 6-phosphate.
Authors: Fujii S , Beutler E
Published: May 2006

The phosphorylation of glucose by human erythrocyte hexokinase follows classical Michaelis-Menten kinetics; hexokinase manifests maximum activity at 5 mM glucose, and no further increase in activity can be measured at higher glucose concentrations. However, the erythrocytes of diabetics and normal erythrocytes incubated with high concentrations of glucose contain increased concentrations of glucose 6-phosphate. To elucidate the mechanism of accumulation of glucose 6-phosphate when erythrocytes are exposed to high glucose concentrations, hexokinase activity was examined in the presence of naturally occurring inhibitors, such as glucose 1,6-bisphosphate, 2,3-diphosphoglycerate, ADP, and glucose 6-phosphate at physiological concentrations. Without inhibitors or in the presence of glucose 1,6-bisphosphate,2,3-diphosphoglycerate, and ADP, maximum hexokinase activity was observed at 5 mM glucose concentration. On the contrary, in the presence of glucose 6-phosphate, hexokinase activity increased at glucose concentrations greater than 5 mM; inhibition by glucose 6-phosphate was partially competitive with glucose. The relief by glucose of glucose 6-phosphate inhibition of hexokinase is a possible explanation of the increased glucose 6-phosphate level in diabetic erythrocytes.
GABAB-receptor-activated K+ current in voltage-clamped CA3 pyramidal cells in hippocampal cultures.
Authors: Gähwiler B H , Brown D A
Published: May 2006

GABAB receptors are a subclass of receptors for gamma-amino-n-butyric acid (GABA) that are also activated by the antispastic drug beta-p-chlorophenyl-GABA (baclofen). One effect of baclofen is to inhibit excitatory transmission from CA3 to CA1 hippocampal pyramidal cells. To identify the ionic mechanism of GABAB-receptor-mediated depression, we have studied the effect of baclofen and GABA on ionic currents in voltage-clamped CA3 pyramidal cell somata in rat hippocampal slice cultures. Baclofen (10 microM) induced an inwardly rectifying outward current that reversed at -74 +/- 4.3 mV (mean +/- SD). This appeared to be a K+ current since (i) its reversal potential showed the expected shift when extracellular K+ concentration was changed and (ii) it was blocked by external Ba2+ or internal Cs+. The action of baclofen was closely imitated by GABA after the GABAA-mediated Cl- current had been abolished with pitrazepin (10 microM); under these conditions, GABA (100 microM) also produced an inwardly rectifying, Ba2+-sensitive current with a reversal potential identical to that of the baclofen-induced current. When outward currents were blocked with internal Cs+, the residual inward voltage-dependent Ca2+ current was not changed by baclofen. It is concluded that the primary effect of GABAB-receptor activation in these neurones is to increase K+ permeability rather than to reduce Ca2+ permeability.
Correlation of ouabain-sensitive ion movements with cell-cycle activation.
Authors: Leister K J , Wenner C E , Tomei L D
Published: May 2006

The role of tumor-promoter-induced Na+, K+-ATPase activity in cell proliferation and the extent of coupling of Na+ and K+ movements to cell-cycle control under differing physiological states was examined. Earlier studies indicated that staging of cells in G1 by serum deprivation in the presence of phorbol esters such as phorbol 12-myristate 13-acetate (PMA) induced a state(s) in which postconfluent C3H 10T1/2 fibroblasts were refractory to ouabain inhibition of DNA synthesis, and the present study further examines this property. Previous findings suggested that the promoter can act in either of two ways: (i) it can act by inducing an alternative pathway to S-phase independent of Na+,K+-ATPase activity, or (ii) the promoter can advance the cells in G1 to a point beyond which Na+, K+-ATPase activity is no longer required for the induction of DNA synthesis. When ouabain (0.3 mM) was added simultaneously with tumor promoters, such as dihydroteleocidin B, to cells arrested in the G1 phase, [3H]thymidine incorporation was inhibited greater than 90%. These data suggest that an alternative pathway is not likely the explanation but that tumor promoters advance cells through a dynamic state in G1, during which progression toward S-phase entry is independent of a Na+,K+-ATPase dependent regulatory step. Ouabain sensitivity kinetics measured by two independent methods indicated that the development of ouabain insensitivity is found in G1 approximately equal to 2 hr prior to S phase. This study indicates that the measured ion movements are markedly dependent on cell-cycle state and describes the criteria required to obtain reproducible responses.
Nucleotide sequence of murine ornithine decarboxylase mRNA.
Authors: Kahana C , Nathans D
Published: May 2006

Ornithine decarboxylase (OrnDCase; L-ornithine carboxy-lyase, EC 4.1.1.17) is the first and rate-limiting enzyme in the biosynthesis of polyamines in mammalian cells. During cell growth the enzyme is regulated by rapid changes in the level of its mRNA and protein. To explore the molecular basis of these changes, we cloned a full-length cDNA copy of the major 2.4-kilobase OrnDCase mRNA from mouse cells and determined its sequence. The cDNA contains 2465 nucleotides derived from OrnDCase mRNA, consisting of a 737-nucleotide-long 5' noncoding segment, a coding segment of 1383 nucleotides terminated by a TAG triplet, and a 342-nucleotide 3' noncoding segment. The encoded protein of 461-amino acid residues has a molecular weight of 51,105 and has a potential site for phosphorylation by casein kinase II. In the unusually long 5' leader sequence, there are four ATG triplets, each of which is followed by an in-phase termination signal; the presence of these upstream ATGs could explain the low in vitro translational activity of OrnDCase mRNA reported earlier. A restriction digest of mouse genomic DNA was probed with a defined OrnDCase coding sequence, revealing a multimembered family of OrnDCase-related genes.
Multiple duplications of complement C4 gene correlate with H-2-controlled testosterone-independent expression of its sex-limited isoform, C4-Slp.
Authors: Levi-Strauss M , Tosi M , Steinmetz M , Klein J , Meo T
Published: May 2006

Mouse liver cDNA clones related to the C4 and C4-Slp isoforms of the fourth component of complement differ by few nucleotide changes within a region of substantial divergence from human C4. It is suggested that the mouse C4 gene duplication is an evolutionarily recent event with respect to the time of mammalian radiation. This conclusion is reinforced by the presence of a single C4 gene in the Syrian hamster. Most H-2 haplotypes, including those characterized by an undetectable C4-Slp protein, possess two C4 gene copies which, in contrast to the neighboring factor B, show a marked restriction site polymorphism. The genetic variation of this region is emphasized by the presence in the mouse of a rare "polymorphism" for C4 gene number. Multiple C4-related gene copies characterize those exceptional wild-derived H-2 haplotypes, H-2w7, H-2w16, and H-2w19, that determine the expression of the C4-Slp protein in female animals.
Expression of p21ras in fresh primary and metastatic human colorectal tumors.
Authors: Gallick G E , Kurzrock R , Kloetzer W S , Arlinghaus R B , Gutterman J U
Published: May 2006

Activation of the cellular oncogene ras has been implicated in many types of human malignancies. In this study, the relative levels of p21 protein product of ras (p21ras) in primary and metastatic colon tumors were compared to those in adjacent normal tissues. Nine of the 17 primary tumors had substantially elevated levels of p21ras with respect to adjacent normal tissues. Eight of these tumors were from Dukes' B and C stages. Four of the five tumors classified as "D" stage (in which distant metastases are present) did not show elevated levels of p21ras. In metastases from primary colon tumors, nine of nine were considerably reduced in p21ras expression regardless of the site of metastasis. These data suggest that elevation of p21ras may be a common event in early stages of colon tumors, and tumor progression may lead to a more autonomous population of cells in which other growth factors supplant the role of this protein.
Quisqualate and L-glutamate inhibit retinal horizontal-cell responses to kainate.
Authors: Ishida A T , Neyton J
Published: May 2006

Currents elicited by L-glutamate and the related agonists quisqualate and kainate were analyzed under voltage clamp in isolated goldfish horizontal cells, using the whole-cell recording configuration of the patch-clamp method [Hamill, O.P., Marty, A., Neher, E., Sakmann, B. & Sigworth, F. J. (1981) Pflügers Arch. 391, 85-100]. These currents resulted from an increase in cationic conductance and were indistinguishable from one another in terms of reversal potential (approximately equal to 0 mV) and apparent elementary conductance (2-3 pS). The power-density spectra of the noise increases produced by each agonist were fit by the sum of two Lorentzian curves having similar cutoff frequencies (tau 1 approximately equal to 5 msec, tau 2 approximately equal to 1 msec), but the relative power of these components were different for quisqualate and glutamate than for kainate. Moreover, the responses to high doses of either quisqualate or glutamate rapidly faded, whereas the responses to kainate did not. Finally, quisqualate and glutamate produced an inhibition of responses to kainate which appeared to be uncompetitive. Kainate, quisqualate, and in our preparation, glutamate appear to activate channels different than those activated by N-methyl-D-aspartate in other preparations. At least some of the effects of quisqualate and glutamate appear to be mediated by receptors bound by kainate.
Studies on angiotensin II and analogs: impact of substitution in position 8 on conformation and activity.
Authors: Aumelas A , Sakarellos C , Lintner K , Fermandjian S , Khosla M C , Smeby R R , Bumpus F M
Published: May 2006

Affinity, residual agonist activity, and inhibitor properties of a series of angiotensin II analogs modified at the COOH-terminal position (X8-substituted peptides) have been probed for structure/conformation-biological activity relationships. The results emphasize (i) the large impact that subtle conformational variations caused by structural alterations in the position 8 side chain have on biological properties, (ii) the implication of the COOH-terminal carboxyl group in both affinity and intrinsic activity, and (iii) the influence that the bulkiness of the side chain in position 8 of antagonists has on the local conformation at the COOH terminus and thus on the inhibitory properties. In the hormone, the phenylalanine-8 ring is required for its steric influence and aromaticity to ensure a fully active conformation at the COOH terminus. Especially, correct orientation of the position 8 carboxyl group relative to the phenyl group of the phenylalanine residue may be necessary for agonistic activation of the angiotensin receptor complex. Replacement of the aromatic ring on the COOH-terminal residue by a nonaromatic group leads to incorrect orientation of the carboxyl group and causes the appearance of antagonist properties. Although the steric effects of the side chain can be modulated by specific interaction of its chemical groups (if any) with the peptide backbone, we found a good correlation between the size of the side chain-e.g., the steric parameter V gamma (the van der Waals volume consisting of the C alpha, C beta, and C gamma atoms), the conformational properties in the backbone (3J HC alpha-NH), and the binding capacities in all compounds tested.
Expression of a mouse long terminal repeat is cell cycle-linked.
Authors: Augenlicht L H , Halsey H
Published: May 2006

The expression of the long terminal repeat (LTR) of intracisternal A particle retroviral sequences which are endogenous to the mouse genome has been shown to be linked to the early G1 phase of the cell cycle in Friend erythroleukemia cells synchronized by density arrest and also in logarithmically growing cells fractionated into cell-cycle compartments by centrifugal elutriation. Regions of homology were found in comparing the LTR sequence to a repetitive Syrian hamster sequence specifically expressed in early G1 in hamster cells.
Investigation of nucleotide binding sites on chloroplast coupling factor 1 with 3'O-(4-benzoyl)benzoyl adenosine 5'-triphosphate.
Authors: Kambouris N G , Hammes G G
Published: May 2006

The subunit locations of each of the three nucleotide binding sites of soluble chloroplast coupling factor 1 have been studied with the photoaffinity label 3'-O-(4-benzoyl)benzoyl-ATP. This derivative is an effective inhibitor of ATPase activity. Photolysis of the radioactive label when bound to each of the three nucleotide sites on the coupling factor has been examined. For the nucleotide site that normally binds ADP very tightly, NaDodSO4/polyacrylamide gel electrophoresis after photolysis indicates that primarily the beta polypeptide chain is appreciably labeled (86%), although some labeling of the alpha polypeptide chain is found (14%). For the site that binds MgATP tightly, 97% of the radioactivity is found on the beta polypeptide chain. The alpha and beta polypeptide chains are labeled in approximately equal amounts when photolysis is carried out with the nucleotide analog bound to the third site.
Monoclonal human thyroid cell line GEJ expressing human thyrotropin receptors.
Authors: Karsenty G , Michel-Bechet M , Charreire J
Published: May 2006

By using the hybridoma technology, a monoclonal human thyroid cell line was obtained by fusing fresh normal human thyroid cells with a human lymphoblastoid cell line. The resultant cell line, called GEJ, has been selected for its expression of thyrotropin (TSH) receptors and has morphological and functional characteristics of normal human thyroid cells. In the presence or absence of human TSH, the GEJ cell line accumulates iodide, produces thyroid hormones, expresses thyroid membrane antigens, and binds approximately equal to 600 molecules of TSH per cell. The binding site for TSH has all the characteristics of specific receptor (i.e., temperature and time dependencies, dissociation of bound TSH only by high amounts of TSH, and a glycoprotein nature). Scatchard analysis described a curvilinear graph with two dissociation constants (Kd = 0.12 X 10(-9) M and 1.6 X 10(-9) M) with, respectively, 1.2 X 10(3) and 7.2 X 10(3) binding sites per cell. This human thyroid cell line that expresses TSH receptors could be a useful tool for the study of human thyroid disorders.
Insulin-like growth factor II (IGF II) in human brain: regional distribution of IGF II and of higher molecular mass forms.
Authors: Haselbacher G K , Schwab M E , Pasi A , Humbel R E
Published: May 2006

Twenty-four distinct areas of human brain were analyzed for the presence of insulin-like growth factor (IGF). As reported for cerebrospinal fluid, only IGF II-like immunoreactivity, but no significant amounts of IGF I-like immunoreactivity, could be found. Upon gel permeation chromatography, two to five distinct size classes were separated on the basis of their immunoreactivity. The smallest component had an apparent molecular mass of 7.5 kDa, identical to the one of purified IGF II from human serum. Radioimmunoassays and a bioassay also gave results indistinguishable from those of serum IGF II. The highest amounts of IGF II-like immunoreactivity occur in the anterior pituitary--namely, 20-25 pmol equivalents/g of wet weight. This is up to 100 times more than in most other brain regions analyzed. The higher molecular mass immunoreactive species were partially characterized. After immunoaffinity purification, the 38- and 26-kDa species are active in a bioassay. Specific IGF-binding protein activity could be shown after purification of the 38- and 26-kDa species on an IGF-affinity column. The 13-kDa species released significant amounts of 7.5-kDa material. The results are interpreted as evidence for the presence of IGF II synthesized locally in human brain. The structure of the larger forms of IGF II-like immunoreactive material as well as the function of IGF II in brain are not yet known.
Adenovirus infection elevates levels of cellular topoisomerase I.
Authors: Chow K C , Pearson G D
Published: May 2006

We have developed a specific, sensitive, and quantitative assay for topoisomerase I, which is based on the formation of a covalent enzyme-DNA intermediate. Our assay measures the quantitative transfer of 32P radioactivity from 32P-labeled DNA to topoisomerase I. Since 32P-labeled topoisomerase molecules are resolved by NaDodSO4/PAGE, HeLa topoisomerase I (100 kDa) and calf thymus topoisomerase I (82 kDa) can be quantitatively assayed in the same reaction mixture. The assay can detect at least 0.3 ng (3 fmol) of topoisomerase I. We have used our assay to measure the levels of topoisomerase I activity in crude extracts of nuclei prepared from uninfected, adenovirus-infected, and adenovirus-transformed human cells. The evidence suggests that an adenovirus early gene product, presumably a protein encoded in early region 1A (E1A), increases cellular topoisomerase I activity at least 10-fold. Immunoblotting analysis with antiserum against calf thymus topoisomerase I shows that the increase in activity is due to an increase in the amount of enzyme.
Induction of transformation and continuous cell lines from normal human mammary epithelial cells after exposure to benzo[a]pyrene.
Authors: Stampfer M R , Bartley J C
Published: May 2006

Rapidly growing primary cultures of normal human mammary epithelial cells (HMEC) were exposed to 1 microgram of benzo[a]pyrene (B[a]P) per ml for two or three 24-hr periods. The B[a]P-treated populations consistently contained cells displaying a longer period of active growth in culture compared to the untreated control cells. Widespread heterogeneity in morphology and growth patterns was evidenced in these "extended life" (EL) cultures, with multiple sequential changes in these parameters occurring during the course of their life in culture. Two apparently immortal continuous cell lines have thus far emerged from these EL cultures. These lines have been characterized to be of human mammary epithelial origin and derived from the originally treated HMEC specimen. The continuous lines do not appear to be malignantly transformed as they do not cause tumor formation in nude mice and show little or no anchorage-independent growth. Nonetheless, they have acquired several properties characteristic of tumor-derived HMEC, which distinguish them from their normal progenitors. These cell lines, as well as the EL strains, may provide useful substrates for studies to determine what agents can induce further transforming events. Additionally, analysis of the multiple steps occurring in the El cultures, as well as in the emergence of the continuous cell lines, could potentially elucidate the processes occurring during human epithelial cell carcinogenesis and escape from senescence.
Isolation of embryonal carcinoma cell lines that express integrated recombinant genes flanked by the Moloney murine leukemia virus long terminal repeat.
Authors: Taketo M , Gilboa E , Sherman M I
Published: May 2006

We have used a producer NIH 3T3 cell line that secretes, together with the helper Moloney murine leukemia virus (Mo-MuLV), a transducing recombinant virus containing the neomycin-resistance gene linked to the Mo-MuLV long terminal repeat (LTR). By infecting three embryonal carcinoma cell lines, PCC4.aza1R, F9tk-, and Nulli-SCC1, with this recombinant virus, we have isolated many transductant clones that stably express the integrated neomycin-resistance gene. These clonal transductant lines consist of undifferentiated embryonal carcinoma cells as judged by morphology, tumorigenicity in 129/Sv mice, and cell-surface antigenic markers. Analysis of the integrated recombinant viral genes by Southern blot hybridization revealed that some of the lines have single copies, whereas others have multiple copies, probably in multiple sites. Although these transductant lines contained many copies of helper Mo-MuLV integrated in the cellular genome, expression of these helper viruses was not detected either by reverse transcriptase activity or by X-C plaque assay. Two F9tk--derived, G418-resistant transductant lines were superinfected with a second recombinant transducing virus that contains the herpes simplex virus thymidine kinase gene flanked by the Mo-MuLV LTR. The frequency of transduction to yield clones able to grow in hypoxanthine/aminopterin/thymidine medium was similar to that of the parental F9tk- cells. These results suggest that the expression of the neomycin-resistance gene, linked to MoMuLV LTR in the transductant embryonal carcinoma cell clones, is due to a cisacting mechanism(s).
Rationale for bone marrow transplantation in the treatment of autoimmune diseases.
Authors: Ikehara S , Good R A , Nakamura T , Sekita K , Inoue S , Oo M M , Muso E , Ogawa K , Hamashima Y
Published: May 2006

Transplantation of normal bone marrow from C3H/HeN nu/nu (H-2k) mice into young MRL/MP-lpr/lpr (MRL/l; H-2k) mice (less than 1.5 mo) prevented the development of autoimmune diseases and characteristic thymic abnormalities in the recipient mice. When female MRL/1 (greater than 2 mo) or male BXSB (H-2b) mice (9 mo) with autoimmune diseases and lymphadenopathy were lethally irradiated and then reconstituted with allogeneic bone marrow cells from young BALB/c nu/nu (H-2d) mice (less than 2 mo), the recipients survived for more than 3 mo after the bone marrow transplantation and showed no graft-versus-host reaction. Histopathological study revealed that lymphadenopathy disappeared and that all evidence of autoimmune disease either was prevented from developing or was completely corrected even after its development in such mice. All abnormal T-cell functions were restored to normal. The newly developed T cells were found to be tolerant of both bone marrow donor-type (BALB/c) and host-type (MRL/1 or BXSB) major histocompatibility complex (MHC) determinants. Therefore, T-cell dysfunction in autoimmune-prone mice can be associated with both the involutionary changes that occur in the thymus of the autoimmune-prone mice and also to abnormalities that reside in the stem cells. However, normal stem cells from BALB/c nu/nu donors can differentiate into normal functional T cells even in mice whose thymus had undergone considerable involution, as in the case of BXSB or MRL/1 mice in the present studies. These findings suggest that marrow transplantation may be a strategy ultimately to be considered as an approach to treatment of life-threatening autoimmune diseases in humans. T-cell dysfunction in autoimmune-prone mice previously attributed to involutionary changes that occur in the thymus of these mice may instead be attributed to abnormalities that basically reside in the stem cells of the autoimmune-prone mice.
Behavioral method for the treatment of idiopathic scoliosis.
Authors: Dworkin B , Miller N E , Dworkin S , Birbaumer N , Brines M L , Jonas S , Schwentker E P , Graham J J
Published: May 2006

Idiopathic scoliosis was treated by an automated portable posture-training device that incorporated precise behavioral principles and enabled therapeutic training to be given in the patients' normal environment throughout the entire day. Twenty-one patient-years of training were completed with a group of 12 adolescent girls selected as being imminently likely to require a brace because of the way their spinal curves had been progressing. As an alternative to conventional brace therapy, patients found the posture-training device considerably less physically restraining and more cosmetically acceptable. Most patients wore it 23 hr per day for at least 1 year and adapted well to the constant physical and psychological presence of the instrument. For 10 patients, the outcome was entirely successful; they were discharged from this pilot study as satisfactorily corrected. Progression of the scoliotic curve was arrested; in fact, there was an average slight improvement in the Cobb angle (a measure of spinal curvature) as measured by x-ray radiography.
Identification and characterization of the human type II collagen gene (COL2A1).
Authors: Cheah K S , Stoker N G , Griffin J R , Grosveld F G , Solomon E
Published: May 2006

The gene contained in the human cosmid clone CosHcol1, previously designated an alpha 1(I) collagen-like gene, has now been identified. CosHcol1 hybridizes strongly to a single 5.9-kilobase mRNA species present only in tissue in which type II collagen is expressed. DNA sequence analysis shows that this clone is highly homologous to the chicken alpha 1(II) collagen gene. These data together suggest that CosHcol1 contains the human alpha 1(II) collagen gene COL2A1. The clone appears to contain the whole gene (30 kilobases in length) and will be extremely useful in the study of cartilage development and for identifying those inherited chondrodystrophies in which defects occur in this gene.
Evidence for a prevalent dimorphism in the activation peptide of human coagulation factor IX.
Authors: McGraw R A , Davis L M , Noyes C M , Lundblad R L , Roberts H R , Graham J B , Stafford D W
Published: May 2006

We have independently isolated and characterized cDNA and genomic clones for the human coagulation factor IX. Sequence analysis in both cases indicates that threonine is encoded by the triplet ACT as the third residue of the activation peptide. This is in agreement with some earlier reports but in disagreement with others that show the alanine triplet GCT at this position. The discrepancy can thus be accounted for by natural variation of a single nucleotide in the normal population. Amino acid sequence analyses of activated factor IX from plasma samples of four individuals yielded two cases of alanine and two cases of threonine at the third position of the activation peptide. In factor IX from pooled plasma and in factor IX from a heterozygous individual, however, both alanine and threonine were found. Taken together, the findings show that a prevalent nondeleterious dimorphism exists in the activation peptide of human coagulation factor IX.
Lack of evidence for skeletal abnormalities in offspring of mice exposed to ethylnitrosourea.
Authors: Lovell D P , Willis D B , Johnson F M
Published: May 2006

Using morphometrical methods, we investigated variation in the skeletons of more than 400 offspring of C57BL/6J and DBA/2J male mice that had received either a 250 mg/kg dose of the mutagen ethylnitrosourea or a solvent control. Sperm involved in the matings developed from cells in the spermatogonial stage at the time the animals were injected. Although variants were detected, differences in frequencies of gross abnormalities and minor variations in shape between treated and control groups were almost all nonsignificant. There were also no major differences in measures of variability within the groups of offspring from either the treated males or the control group. Additional examination of the skeleton for changes in the frequency of a series of nonmetrical variants also provided no evidence of differences between the treated and control groups that could be attributed to induced mutations. These results conflict with previous findings that ethylnitrosourea is a potent inducer of dominant skeletal mutations.
Restriction fragment length polymorphism of the human c-fms gene.
Authors: Xu D Q , Guilhot S , Galibert F
Published: May 2006

By using blot hybridization with a v-fms probe, a polymorphism for EcoRI, HindIII, and BamHI restriction endonuclease sites associated with the human c-fms locus was observed in a random adult population. This restriction fragment length polymorphism can be explained on the basis of the existence of two alleles, a and b, and is due to a short (congruent to 500 base pairs) deletion characteristic of allele a. The distribution in the analyzed population (48 unrelated individuals) is 23% heterozygotes ab, 75% homozygotes bb, and 2% homozygotes aa. Though the inheritance of this polymorphism follows a Mendelian pattern, the children from couples ab X bb are of the following genotype: 74% ab and 26% bb. These deviations from the expected frequencies of 50% suggest a selective pressure in favor of heterozygotes.
Deletions near the albino locus on chromosome 7 of the mouse affect the level of tyrosine aminotransferase mRNA.
Authors: Schmid W , Müller G , Schütz G , Gluecksohn-Waelsch S
Published: May 2006

Overlapping chromosomal deletions at the albino locus on chromosome 7 of the mouse affect the expression of several liver enzymes, including tyrosine aminotransferase (TAT; L-tyrosine:2-oxoglutarate aminotransferase, EC 2.6.1.5). With cloned TAT DNA the integrity of the TAT structural gene and its expression and inducibility by glucocorticoids and cAMP were examined in deletion homozygous mice. No difference in the structure of the gene between normal and mutant mice was detected by Southern blotting. Severely reduced amounts of TAT mRNA were detected in homozygous mutants. The residual mRNA levels could not be modulated by glucocorticoids or cAMP. We conclude that a trans-acting control function required for expression and inducibility of mouse TAT can be assigned to the chromosomal region near the albino locus.
Selective expression of rat pancreatic genes during embryonic development.
Authors: Han J H , Rall L , Rutter W J
Published: May 2006

We present the developmental profiles of the mRNAs of 10 selectively expressed pancreatic exocrine genes and of insulin. The mRNA profiles fall into three related classes, but each profile is in some respect unique. The data on gene expression suggest there are four developmental states of the exocrine pancreas: early morphogenesis and low-level gene expression (the protodifferentiated state), the embryonic differentiated state, a modulated state in neonatal animals, and the adult differentiated state. Each state is characterized by distinct ratios of the exocrine mRNAs and presumably involves a distinct regulatory transition. This complex differentiative program must involve multiple regulatory molecules.
Natural populations of Trypanosoma cruzi, the agent of Chagas disease, have a complex multiclonal structure.
Authors: Tibayrenc M , Ward P , Moya A , Ayala F J
Published: May 2006

We have studied 15 gene loci coding for enzymes in 121 Trypanosoma cruzi stocks from a wide geographic range--from the United States and Mexico to Chile and southern Brazil. T. cruzi is diploid but reproduction is basically clonal, with very little if any sexuality remaining at present. We have identified 43 different clones by their genetic composition; the same genetic clone is often found in very distant places and in diverse hosts. There is much genetic heterogeneity among the different clones, and they cannot be readily classified into a few discrete groups that might represent natural taxa. These findings imply that the biological and medical characteristics need to be ascertained separately for each natural clone. The evidence indicates that clonal evolution is very ancient in T. cruzi. We propose two alternative hypotheses concerning the relationship between the biochemical diversity and the heterogeneity in other biological and medical characteristics of T. cruzi. One hypothesis is that the degree of diversity between strains simply reflects the time elapsed since their last common ancestor. The second hypothesis is that biological and medical heterogeneity is recent and reflects adaptation to different transmission cycles. A decision between the two hypotheses can be reached with appropriate studies, with important medical consequences.
The gene for human p53 cellular tumor antigen is located on chromosome 17 short arm (17p13).
Authors: McBride O W , Merry D , Givol D
Published: May 2006

A clone that cross-hybridizes with a mouse p53 probe has been isolated from a cDNA library of simian virus 40-transformed human fibroblasts. This cloned human p53 cDNA was used as a probe to examine DNAs obtained from human-rodent somatic cell hybrids that have segregated human chromosomes. The results show that the human p53 gene is located on chromosome 17. In addition, Southern analysis of hybrids prepared from human cells containing a chromosome 17 translocation allowed regional localization of the human p53 gene to the most distal band on the short arm of this chromosome (17p13). Localization of the p53 gene to 17p13 was confirmed by in situ hybridization of metaphase spreads with the human p53 probe.
Association of I-J determinants with lipomodulin/macrocortin.
Authors: Jardieu P , Akasaki M , Ishizaka K
Published: May 2006

Stimulation with glucocorticoids of mouse splenic lymphocytes and peritoneal adherent cells resulted in the formation of a soluble factor--i.e., glycosylation inhibiting factor (GIF)--that inhibits the assembly of N-linked oligosaccharide(s) to IgE-binding factors during their biosynthesis. The major cell sources of GIF are Lyt 2+ I-J+ T cells and macrophages, respectively. The molecular size of GIF from T cells was 15 kDa, while GIF from macrophages consisted of 40- and 15-kDa molecules. GIF from both cell sources bound to monoclonal antibody against lipomodulin and exerted phospholipase inhibitory activity upon dephosphorylation. In view of previous reports that glucocorticoids induce the formation of phospholipase inhibitory protein--i.e., lipomodulin/macrocortin--GIF from T cells and macrophages appear to be phosphorylated derivatives of lipomodulin. GIF released from splenic lymphocytes and macrophages of C57BL/6 mice bound to anti-I-Jb antibodies but not to either anti-I-Jk or anti-I-Js antibodies. Upon stimulation with glucocorticoids, CBA and B10.A(5R) lymphocytes released GIF that bound to anti-I-Jk antibodies but not to anti-I-Jb antibodies, while the same factor from B10.A(3R) lymphocytes bound to anti-I-Jb antibodies. The results indicate that I-J determinants are associated with lipomodulin/macrocortin from T cells and macrophages.
An alternative technique for the computation of the designator in the retinex theory of color vision.
Authors: Land E H
Published: May 2006

Accepting the first postulate of the retinex theory of color vision that there are three independent lightness-determining mechanisms (one for long waves, one for middle waves, and one for short waves), each operative with less than a millisecond exposure and each served by its own retinal pigment, a basic task of retinex theory becomes the determination of the nature of these mechanisms. Earlier references proposed several workable algorithms. [Land, E. H. (1959) Proc. Natl. Acad. Sci. USA 45, 115-129; Land, E. H. (1959) Proc. Natl. Acad. Sci. USA 45, 636-644; Land, E. H. (1983) Proc. Natl. Acad. Sci. USA 80, 5163-5169; Land, E. H. & McCann, J. J. (1971) J. Opt. Soc. Am. 61, 1-11; Land, E. H. (1986) Vision Res. 26, 7-21.] The present paper describes a relatively simple alternative technique for the computation of the designator in retinex theory and reports the general operational effectiveness of the new technique, including the competence, not possessed by earlier algorithms, for generating Mach bands.
Homology between RNA polymerases of poxviruses, prokaryotes, and eukaryotes: nucleotide sequence and transcriptional analysis of vaccinia virus genes encoding 147-kDa and 22-kDa subunits.
Authors: Broyles S S , Moss B
Published: May 2006

We have determined the nucleotide sequence of a region of the vaccinia virus genome encoding RNA polymerase subunits of 22 and 147 kDa and have mapped the 5' and 3' ends of the two mRNAs. The predicted amino acid sequence of the vaccinia 147-kDa subunit shows extensive homology with the largest subunit of Escherichia coli RNA polymerase, yeast RNA polymerases II and III, and Drosophila RNA polymerase II. The regions of homology between the five RNA polymerases are subdivided into five separate domains that span most of the length of each. A sixth domain shared by the vaccinia and the eukaryotic polymerases is absent from the E. coli sequence. In all specified regions, the vaccinia large subunit has greater homology with eukaryotic RNA polymerases II and III than with the E. coli polymerase. Vaccinia virus and eukaryotic RNA polymerases may therefore have evolved from a common ancestral gene after the latter diverged from prokaryotes.
Murine myb protooncogene mRNA: cDNA sequence and evidence for 5' heterogeneity.
Authors: Bender T P , Kuehl W M
Published: May 2006

We have sequenced two overlapping cDNA clones from a murine pro-B cell library to generate a composite sequence that includes 3413 bases of the murine c-myb mRNA. There is a single long open reading frame, beginning at the first base of this sequence, and continuing from the first methionine codon at nucleotide 265 to a TGA termination codon at nucleotide 2173. The predicted murine translation product contains 636 amino acid residues and is about 71 kDa long, which is in good agreement with the 75-kDa molecular size determined for the avian c-myb protein. The murine c-myb protein shows a striking 82% amino acid homology in the region (amino acids 71-444) where it can be compared to the published avian c-myb gene sequence. S1 nuclease protection analysis indicates extreme heterogeneity at the 5' end of steady-state murine c-myb mRNA.
Regulation of bacteriophage P2 late-gene expression: the ogr gene.
Authors: Christie G E , Haggård-Ljungquist E , Feiwell R , Calendar R
Published: May 2006

The ogr gene product of bacteriophage P2 is a positive regulatory factor required for P2 late-gene transcription. We have determined the nucleotide sequence of the ogr gene, which encodes a basic polypeptide of 72 amino acids. P2 growth is blocked by a host mutation, rpoA109, in the alpha subunit of DNA-dependent RNA polymerase. The ogr52 mutation, which allows P2 to grow in an rpoA109 strain, was shown to be a single nucleotide change, in the codon for residue 42, that changes tyrosine to cysteine. The predicted amino acid sequence of the Ogr protein does not show similarity to DNA-binding proteins that are known to affect promoter recognition, to sigma factors, or to other characterized transcriptional regulatory proteins. We have inserted the ogr gene into a plasmid under control of the leftward promoter and operator of bacteriophage lambda. Thermal induction of ogr gene expression in this plasmid results in overproduction of a small protein that has been shown by complementation to possess Ogr function.
Expression of cell cycle-dependent genes in young and senescent WI-38 fibroblasts.
Authors: Rittling S R , Brooks K M , Cristofalo V J , Baserga R
Published: May 2006

We studied the expression of 11 cell cycle-dependent genes in senescent WI-38 fibroblasts and compared the results to those obtained in WI-38 cells from early passages (young cells). Every gene we examined is expressed in the senescent cells at levels similar to those in the young cells, including two genes maximally expressed at the G1/S phase boundary--genes for thymidine kinase and histone H3. The results clearly show that senescent, noncycling WI-38 cells are not similar to quiescent cells. Rather, such senescent WI-38 cells may be blocked just prior to the onset of DNA synthesis.
Trans-acting amplification mutants and other eggshell mutants of the third chromosome in Drosophila melanogaster.
Authors: Snyder P B , Galanopoulos V K , Kafatos F C
Published: May 2006

We report on the characterization of five third chromosome mutations with strong effects on the formation of the eggshell or chorion. Three mutations, defining two loci, result in substantially reduced follicle cell-specific amplification of the major chorion structural genes and, hence, in underproduction of the corresponding mRNAs and proteins. The other two mutations, though displaying structural chorion abnormalities, appear to have no significant effect on amplification and to express normally the major chorion structural genes. The possible nature of these mutations is discussed.
Yeast RPO41 gene product is required for transcription and maintenance of the mitochondrial genome.
Authors: Greenleaf A L , Kelly J L , Lehman I R
Published: May 2006

A 4-kilobase DNA fragment carried by a recombinant lambda gt11 bacteriophage appears to contain most of the coding information for the 145-kDa subunit of the Saccharomyces cerevisiae mitochondrial RNA polymerase. The RPO41 gene is located on chromosome VI, as determined by hybridization to electrophoretically separated yeast chromosomes. Hybridization and gene disruption/replacement experiments show that the RPO41 gene exists in a single copy and that its product is required for transcription and maintenance of the mitochondrial genome.
Tumor rejection antigens of chemically induced sarcomas of inbred mice.
Authors: Srivastava P K , DeLeo A B , Old L J
Published: May 2006

Chemically induced sarcomas of inbred mice are immunogenic in syngeneic hosts, and preimmunization with tumor cells leads to resistance to subsequent tumor transplants. The tumor rejection antigens (TRAs) that mediate this reaction are highly specific for each tumor; cross-protection between different syngeneic sarcomas is rare. Isolated membrane and cytosol fractions from two antigenically distinct BALB/c sarcomas, Meth A and CMS5, have TRA activity, and biochemical characterization of the active components from the cytosol and plasma membranes of these two tumors identified a glycoprotein of Mr 96,000. Immunization with unfractionated Meth A cytosol frequently leads to tumor enhancement, but the tumor-enhancing activity (TEA) is lost on fractionation and TRA activity becomes demonstrable. As Meth A and CMS5 lack expression of murine leukemia virus (MuLV) antigens or transcripts, MuLV-related antigens cannot be involved in the TEA or TRA activities of these tumors. In contrast to the lack of cross-reactivity between Meth A and CMS5 TRAs in transplantation tests, rabbit antiserum prepared against the Meth A Mr 96,000 antigen reacted with the CMS5 Mr 96,000 antigen. In view of the biochemical and antigenic similarities of Meth A and CMS5 TRAs, we propose that structurally related but distinct Mr 96,000 glycoproteins are expressed in chemically induced sarcomas and that these molecules are responsible for the individually specific immunogenicity of these tumors.