cDNA expression studies of rat liver aryl sulphotransferase

A cDNA encoding an isoenzyme of rat liver aryl sulphotransferase was isolated from a rat liver bacteriophage Lambda gt 11 library by the polymerase chain reaction technique. The resulting cDNA was functionally expressed in COS-7 cells and characterised by determining the sulphating capacity of the cells with a range of substrates. The COS-expressed enzyme catalysed the sulphation of both phenol and dopamine with Kms of the same order as those obtained for the high affinity isozyme in rat liver cytosol, while low activity was observed with tyrosine methyl ester. The common food additive vanillin was also a good substrate for sulphate conjugation. The sulphation of vanillin catalysed by the COS-expressed enzyme was consistent with a single enzyme system, in contrast, the kinetics of the reaction catalysed by cytosolic sulphotransferase indicated that vanillin was sulphated by more than one isozyme.

Cloning of the rat insulin- like growth factor binding protein-5 gene and DNA sequence analysis of its promoter region

To understand the regulation of the insulin-like growth factor binding protein-5 (IGFBP-5) gene expression, we have cloned the IGFBP-5 gene from rat genomic libraries and determined its genomic organization as well as the DNA sequence at the 5' flanking region of the gene. The rat IGFBP-5 gene spans at least 17 kilobases (kb) of the genome and contains 4 exons interrupted by 3 introns of approximately 10, 0.6 and 0.7 kb, respectively. Southern blot analysis of the rat chromosome DNA revealed a single copy gene for IGFBP-5 in the haploid genome. Primer extension experiments demonstrated a single transcriptional start site located at 772 nucleotides 5' of the ATG translational start codon. In addition to a TATA box and a CAAT box, multiple putative cis-regulatory elements, including an AP-1, an AP-2 and a binding site for progesterone receptor are present in the promoter region. This finding suggests that the IGFBP-5 gene is one of those that are expressed in a tissue-specific manner.

The dosimetry of iodine-123-labeled TISCH: a SPECT imaging agent for the D1 dopamine receptor

TISCH is an iodinated D1 specific dopamine receptor antagonist that may be useful as a SPECT imaging agent. This report documents its pharmacological safety in animals and its radiation dosimetry in humans. The dose of radiation that 123I-TISCH delivered to seven healthy subjects was estimated with the absorbed fraction technique. Conjugate images of the body were serially acquired for up to 24 hr after the administration of a known amount of activity. The count rates in the organs that could be visualized were measured on each image. These count rates were corrected for attenuation with 123I transmission scans. The doses to the other organs that did not take up enough activity to be visualized on the images were estimated with established models. The dosimetry was calculated for each subject individually before the results were averaged. Rapid biological washout minimizes the radiation exposure to most organs. The dose to the large bowel is limiting in healthy volunteers. The proximal colon receives about 0.67 rad/mCi (180 microGy/MBq) or about 5 rads for every 7.5 mCi of TISCH injected. This low radiation burden should make it feasible to study the D1 dopamine receptor in patients who have neuropsychiatric disorders before and after treatment.

A luteinizing hormone receptor with a severely truncated cytoplasmic tail (LHR-ct628) desensitizes to the same degree as the full-length receptor

The wild type murine luteinizing hormone (mLH) receptor, which in its mature form is predicted to be a protein of 674 amino acids (mLHR), and an artificially mutated form lacking the last 46 amino acids (mLHR-ct628) were stably expressed in murine L cells. Both forms stimulated adenylyl cyclase and underwent rapid desensitization. The mutation removed 1 tyrosine, 2 threonines, and 6 serines from the receptor. The results indicate that none of these potential phosphorylation sites participates in either adenylyl cyclase stimulation or receptor desensitization. Our results with the mLHR-ct628 (carboxyl-terminal amino acid sequence CCKHRAEL) differ from those reported recently for the essentially identically mutated rat LHR that lacks the last 43 amino acids (rLHR-ct631 with carboxyl-terminal amino acid composition CCKRRAELYRR). This 43-amino acid truncation was described to have the effect of preventing hormone-induced desensitization. While the reasons for the discrepant results are not known, our results do not support the proposal for a participatory role of the extreme carboxyl terminus of the receptor in its desensitization.

Mass spectrometric analysis of opioid and tachykinin neuropeptides in non-secreting and ACTH-secreting human pituitary adenomas

In a study to test the hypothesis that defects in the metabolism of neuropeptides might be a contributing factor to human anterior pituitary tumor formation, the proenkephalin A, proopiomelanocortin (POMC), and tachykinin systems, which produce methionine enkephalin (ME), beta-endorphin (BE), and substance P (SP), respectively, were measured in patients who had a wide variety of pituitary tumors. Mass spectrometry was used to optimize the level of molecular specificity of the ME and BE analytical measurements, and radioimmunoassay was used to measure SP-like immunoreactivity (SP-li). Compared to data obtained from pituitaries from post-mortem controls, the non-secreting tumors contained a significantly lower amount of the POMC neuropeptide, BE. The lower ME level was not significant. However, two adrenocorticotrophic hormone (ACTH)-secreting tumors contained ME, BE, and SP-li amounts that were much higher than both the controls and nonsecreting tumors. These data suggest that a hypometabolism of the POMC precursor may be operating in non-secreting tumors, and that a hypermetabolism of the proenkephalin A, POMC, and tachykinin precursors may be operating in two ACTH-secreting tumors. These data demonstrate that mass spectrometry plays a critical role in the study of human pituitary tumors.

Molecular cloning of cellular genes encoding retinoblastoma-associated proteins: identification of a gene with properties of the transcription factor E2F

The retinoblastoma protein interacts with a number of cellular proteins to form complexes which are probably crucial for its normal physiological function. To identify these proteins, we isolated nine distinct clones by direct screening of cDNA expression libraries using purified RB protein as a probe. One of these clones, Ap12, is expressed predominantly at the G1-S boundary and in the S phase of the cell cycle. The nucleotide sequence of Ap12 has features characteristic of transcription factors. The C-terminal region binds to unphosphorylated RB in regions similar to those to which T antigen binds and contains a transactivation domain. A region containing a potential leucine zipper flanked by basic residues is able to bind an E2F recognition sequence specifically. Expression of Ap12 in mammalian cells significantly enhances E2F-dependent transcriptional activity. These results suggest that Ap12 encodes a protein with properties known to be characteristic of transcription factor E2F.

Cross-linking of surface immunoglobulin activates src-related tyrosine kinases in WEHI 231 cells

Crosslinking of sIgM on the B cell line WEHI 231 with anti-sIgM antibody induces protein tyrosine phosphorylation, implicating protein tyrosine kinases (PTKs) in sIg-mediated signal transduction. We have analyzed this cell line for members of the src family of PTKs and have evaluated whether these PTKs might be involved in the process of sIgM-mediated signaling. Our results show that Blk, Lyn, Lck, and Hck are detectable in WEHI 231 cells. Addition of antibodies to sIgM were found to variably stimulate the activities of Blk, Lyn, Lck, and Hck as measured by immune-complex protein kinase assays. Autophosphorylation of these src PTKs, as assessed by reaction with anti-phosphotyrosine antibodies, increased over the time course of sIgM-mediated activation. Co-immunoprecipitation studies to investigate the potential physical interaction of src PTKs with the sIgM receptor complex revealed that, under digitonin and Brij 96 lysis conditions Lyn, Lck, Hck, but not Blk associated with sIgM.

Activation of resting peripheral blood lymphocytes through the T cell receptor induces rapid phosphorylation of Op18

Op18 is a highly conserved major cytosolic phosphoprotein that has been implicated in signal transduction in a wide variety of cell types. Freshly isolated peripheral blood lymphocytes (PBL) constitutively express low levels of mostly unphosphorylated Op18. After mitogenic stimulation of PBL, Op18 synthesis is induced at a time when cells are entering S-phase. In this study, we have examined the phosphorylation of Op18 in freshly isolated PBL after activation of the T cell receptor by OKT3. Quantitative analysis of Op18 phosphorylation was undertaken by metabolic labeling with 32Pi and PhosphorImager analysis of two-dimensional gels. After 10 or 15 min of activation by OKT3, one of the three major phosphorylated forms of Op18, designated Op18c, increased approximately 10-fold, which represented a most pronounced change among a large number of phosphoproteins analyzed. In time course experiments, increased Op18 phosphorylation to yield Op18c was observed as early as 2 min. Continued OKT3-induced activation for 20 to 72 h resulted in a further increase in phosphorylated Op18 forms, which paralleled new Op18 synthesis and occurred at a time when cells were entering S-phase, as determined by [3H]-thymidine incorporation. Inhibitors of lymphoid proliferation, cyclosporin A and RPM, had no effect on early (less than 15 min) phosphorylation. Addition of calphostin C, a specific inhibitor of protein kinase C, 1 min prior to stimulation of resting T cells with OKT3 completely inhibited further phosphorylation of Op18. Incubation of PBL with calphostin C for 75 min decreased constitutive levels of phosphorylated Op18. In contrast, inhibition of cyclic nucleotide-dependent protein kinases with HA1004 had no effect on Op18 phosphorylation. Activation of cAMP-dependent protein kinase with Forskolin or 8Br-cAMP did not increase Op18 phosphorylation. Our results suggest that Op18 phosphorylation is mediated by protein kinase C activation as an early event in T cell activation through the T cell receptor.

Activation of resting peripheral blood lymphocytes through the T cell receptor induces rapid phosphorylation of Op18

Op18 is a highly conserved major cytosolic phosphoprotein that has been implicated in signal transduction in a wide variety of cell types. Freshly isolated peripheral blood lymphocytes (PBL) constitutively express low levels of mostly unphosphorylated Op18. After mitogenic stimulation of PBL, Op18 synthesis is induced at a time when cells are entering S-phase. In this study, we have examined the phosphorylation of Op18 in freshly isolated PBL after activation of the T cell receptor by OKT3. Quantitative analysis of Op18 phosphorylation was undertaken by metabolic labeling with 32Pi and PhosphorImager analysis of two-dimensional gels. After 10 or 15 min of activation by OKT3, one of the three major phosphorylated forms of Op18, designated Op18c, increased approximately 10-fold, which represented a most pronounced change among a large number of phosphoproteins analyzed. In time course experiments, increased Op18 phosphorylation to yield Op18c was observed as early as 2 min. Continued OKT3-induced activation for 20 to 72 h resulted in a further increase in phosphorylated Op18 forms, which paralleled new Op18 synthesis and occurred at a time when cells were entering S-phase, as determined by [3H]-thymidine incorporation. Inhibitors of lymphoid proliferation, cyclosporin A and RPM, had no effect on early (less than 15 min) phosphorylation. Addition of calphostin C, a specific inhibitor of protein kinase C, 1 min prior to stimulation of resting T cells with OKT3 completely inhibited further phosphorylation of Op18. Incubation of PBL with calphostin C for 75 min decreased constitutive levels of phosphorylated Op18. In contrast, inhibition of cyclic nucleotide-dependent protein kinases with HA1004 had no effect on Op18 phosphorylation. Activation of cAMP-dependent protein kinase with Forskolin or 8Br-cAMP did not increase Op18 phosphorylation. Our results suggest that Op18 phosphorylation is mediated by protein kinase C activation as an early event in T cell activation through the T cell receptor.

Derivation of the threshold pump power of erbium-doped fiber lasers

Starting from the rate equations describing the interaction between a three-level atom and a two-wavelength field appropriate to the erbium-doped fiber lasers pumped by 980-nm light, we establish an analytical and explicit expression for the threshold pump power of the laser. From this it is then shown that a relationship between the threshold power and other primary system parameters can be quantitatively specified.

[Acute effect of small dosages of somatostatin analogue SMS201-995 on gallbladder contractility in normal adults]

Recently, a long-acting, somatostatin analogue, SMS201-995(SMS), has been developed and extensively investigated. It has been proved to be remarkably effective in treating many diseases, including active acromegaly. We observed the effect of SMS on gallbladder contractility in normal adults using the fatty meal test. Our results show that gallbladder contractility was inhibited significantly for 6 hours after the subcutaneous injection of SMS in dosages of 50, 25, 12.5, and 5 micrograms. We conclude that it is not practical to avoid gallbladder disfunction during long-term SMS treatment by decreasing the dosages of SMS.

Evidence that the hamster tunicamycin resistance gene encodes UDP-GlcNAc:dolichol phosphate N-acetylglucosamine-1-phosphate transferase

A cDNA clone isolated from Chinese hamster ovary cells conferred elevated GlcNAc-1-P-transferase (GPT) activity and resistance to tunicamycin in transfected cells (Zhu, X., and Lehrman, M. A. (1990) J. Biol. Chem. 265, 14250-14255). It had been assumed that this cDNA, termed TRG for tunicamycin resistance gene, encoded GPT enzyme. However, other functions were not ruled out. Thus, by one of several mechanisms, the TRG protein could have instead functioned by activation of the transfected host's endogenous GPT enzyme. To analyze the biochemical function of the TRG protein, hamster TRG cDNA was stably expressed at high levels in Chinese hamster ovary cells. In addition, several antipeptide polyclonal antibodies directed against the predicted TRG protein were obtained. With these tools in hand, experiments were performed to test the hypothesis that the TRG encodes GPT enzyme, as well as to rule out other possible functions for the TRG protein. These experiments included examination of the effects of solubilization of membranes on TRG-dependent GPT activity, the apparent binding of tunicamycin to the TRG protein, and the immunoadsorption of GPT activity with TRG protein-specific antibodies. From these results, we conclude that the hamster TRG most likely encodes GPT enzyme.

[Analysis of chemical constituent of essential oil in Lonicera japonnica Thunb. cultivated on the northern plain of Henan Province]

The chemical constituents of the essential oil in the dry flower and fresh flower of Lonicera japonica were analyzed by the GC-MS-DS technique and the superimposition of authentic samples. 27 and 30 monoterpenoids and sesquiterpenoids were identified from the essential oil of the dry flower and fresh flower respectively. The major constituents have been found to be linalool, geraniol, aromadendrene and eugenol etc.

Mechanisms of loss of heterozygosity in retinoblastoma

Retinoblastoma (RB) tumors arise when both alleles of the RB1 gene are inactivated by two mutational events (M1 and M2). M1 can be an initial germline or somatic mutation; M2 is frequently loss of heterozygosity (LOH), which makes the cell homozygous or hemizygous for the original mutation. LOH is the major mechanism by which many cancers are initiated. To further delineate the mechanism of LOH, we screened a total of 37 RB tumors for LOH by Southern blot analysis. The tumors were from 17 bilaterally and 17 unilaterally affected patients. Nineteen of 30 informative tumors (63%) from 27 patients showed LOH. Proximal and distal flanking markers on chromosome 13 were informative in 13 tumors, allowing evaluation of the mechanisms by which LOH occurred. Mitotic recombination was implicated in 6 (46%) of the 13 tumors.

Diacylglycerol composition and metabolism in peripheral nerve

The content and molecular species composition of 1,2-diacylglycerol (DAG) in rat sciatic nerve was determined and compared with the molecular species profiles for glycerophospholipid classes in order to gain information concerning the metabolic pathways of DAG formation. The level of DAG in freshly dissected epineurium-free nerve (44 +/- 2 pmol/mg wet weight) was 10-40% of that in other tissues and cultured cells. The predominant DAG molecular species were 18:0/20:4 (30%) and 16:0/18:1 (17%). In comparison with phospholipid molecular species patterns, DAG was characterized by a substantial but lower proportion of the 18:0/20:4 species than was found in phosphoinositides, and a significant fraction of saturated species such as those found in phosphatidylcholine. In nerve from diabetic rats, both the content and arachidonoyl-containing molecular species of DAG were reduced. These species were also decreased in individual glycerophospholipids, except for phosphatidylinositol. The distribution of molecular species in phosphatidic acid (PA) did not resemble that of any other phospholipid. A large rise in DAG content occurred when nerve was incubated in vitro. Molecular species analysis indicated that phosphoinositides were the main source, especially during the initial period. This process was virtually abolished in a Ca(2+)-free medium and probably reflects a response to tissue injury. Evidence was obtained for the isomerization of DAG to 1,3-diacylglycerol during incubation. PA content and molecular species composition of incubated nerve did not change. However, inclusion of propranolol, a PA phosphatase inhibitor, caused a 40% accumulation of PA within 10 min, suggesting that formation of this phospholipid is continuous. These findings support the conclusion that DAG is principally derived from phosphoinositides by phospholipase C hydrolysis, but a minor fraction could be derived from phosphatidylcholine either by the action of phospholipase C or via phospholipase D and PA phosphatase. The metabolic origins of PA appear to be diverse.

Construction of hybridomas secreting monoclonal antibody against sweet potato feathery mottle virus and use of antibody for detection of SPFMV

Two hybridomas stably secreting monoclonal antibodies (McAb) against sweet potato feathery mottle virus (SPFMV) were constructed by fusing mouse myeloma (Sp2/0-Ag14) with mouse splenocytes immunized with SPFMV-LF. The McAb secreted by the two hybridomas specifically reacted with both SPFMV-LF (China strain) and SPFMV-RC (American strain) in dot-blot-ELISA. A large amount of McAb was produced with BALB/c mice. The titer of hybridoma cultured supernatant was 1:256, and that of the ascitic fluids was 1:1 x 10(4); and the immunoglobulins of McAb were IgG2a and IgG3 respectively. The detection of SPFMV-infected sweet potato plants with McAb confirmed that the McAb obtained in this test were desirable for large-scale routine surveys of SPFMV. This study on construction of hybridomas and detection of SPFMV using McAb is the first report in the world.

Targeted integration of adeno-associated virus (AAV) into human chromosome 19

A key feature in adeno-associated virus (AAV) replication is efficient integration of the viral genome into host cell DNA to establish latency when helper virus is absent. The steps involved in this process remain largely uncharacterized, even though AAV integration was first documented 20 years ago. Using a protein--DNA binding method we isolated AAV--cellular junction DNA sequences. The cellular component hybridized to a single restriction fragment in the virus-free parental cell line, and also co-migrated with AAV-specific sequences in numerous latently infected cell lines. Analysis of somatic cell hybrids indicated that this cellular sequence maps to the distal portion of the q arm of human chromosome 19. In situ hybridization of AAV DNA to chromosomes from latently infected cells confirms the physical location of AAV integrations to be q13.4-ter of chromosome 19. Sequence analysis of several independent integration sites shows breakpoints occurring within a 100 bp cellular region. This non-pathogenic parvovirus thus appears to establish viral latency by integrating its DNA specifically into one chromosomal region. Such specific integration is so far unique among the eukaryotic DNA viruses. The incorporation of site-specific integration into AAV vector schemes should make this vector system attractive for human gene therapy approaches.

A new polymorphic probe on chromosome 6q: p327A (D6S93)

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[The preparation of highly purified insulin and its clinical use. Insulin Cooperative Study Group]

Antigenicity of insulin preparations is obviously related to their purity. The average contents of proinsulin, glucagon and pancreatic polypeptide in highly purified insulin (HP-I) produced by us are 76.0, 2.11 and 0.11 ppm respectively. These results are superior to those for domestic conventional crystalline insulin and single peak insulin (SP-I). The antibodies to insulin, proinsulin and pancreatic polypeptide in serum were examined in 24 diabetic patients treated with HP-I for more than 6 months. The positive rates for the above three antibodies were 37.5%, 0% and 0% respectively. The results showed that the antigenicity of HP-I was much lower than that of domestic conventional crystalline insulin and almost the same as that of MC-I from Nordisk, Denmark.

Pro-peptide as an intramolecular chaperone: renaturation of denatured subtilisin E with a synthetic pro-peptide [corrected]

The amino-terminal pro-sequence consisting of 77 amino acid residues is required to guide the folding of secreted subtilisin E, a serine protease, into active, mature enzyme (ikemura et al., 1987). Furthermore, denatured subtilisin E can be folded to active enzyme in an intermolecular process with the aid of an exogenously added pro-subtilisin E, the active site of which was mutated (Zhu et al., 1989). In this report, we have synthesized the pro-peptide of 77 residues (corresponding to -1 to -77 in the sequence, where residue +1 is the N-terminal amino acid residue of the mature protein), and have found that it could intermolecularly complement the folding of denatured subtilisin E to active enzyme. Furthermore, we have found that the synthetic pro-peptide exhibits specific strong binding to the active mature enzyme by inhibiting it competitively at its active centre with an upper limit to a Ki of 5.4 x 10(-7). In contrast, synthetic pro-peptides corresponding to -44 to -77, -1 to -64 and -1 to -43 inhibited the enzyme with Ki values weaker by two orders of magnitude. The results indicate that the sequence extending from -1 to -77 is essential for specificity of interaction, perhaps generating a conformation that accounts for both roles found hitherto, i.e. specific binding to the active centre, and guiding of the refolding to active enzyme. Thus these results suggest that the pro-peptide functions as an intramolecular chaperone [corrected].

The interspersed DNA repeat conserved in water birds' genomes

A putative old and ubiquitous interspersed DNA repeat family was identified from TaqI restriction, M13 cloning, and sequencing of the genomic DNA of a Mallard (Anas platyrhynchos), a Muscovy Duck (Cairina moschata), a Toulouse Goose (Anser anser), and a Black Swan (Cygnus atratus). A 425-bp consensus core sequence was obtained for the interspersed family. The 425-bp unit was about 2% of the avian genome and was found to be conserved in at least four genera of the order Anseriforme: Anas, Anser, Cairina, and Cygnus.

Three-dimensional structures of acidic and basic fibroblast growth factors

Members of the fibroblast growth factor (FGF) family of proteins stimulate the proliferation and differentiation of a variety of cell types through receptor-mediated pathways. The three-dimensional structures of two members of this family, bovine acidic FGF and human basic FGF, have been crystallographically determined. These structures contain 12 antiparallel beta strands organized into a folding pattern with approximate threefold internal symmetry. Topologically equivalent folds have been previously observed for soybean trypsin inhibitor and interleukins-1 beta and -1 alpha. The locations of sequences implicated in receptor and heparin binding by FGF are presented. These sites include beta-sheet strand 10, which is adjacent to the site of an extended sequence insertion in several oncogene proteins of the FGF family, and which shows sequence conservation among the FGF family and interleukin-1 beta.

Investigation of copper-PTSM as a PET tracer for tumor blood flow

Copper-PTSM has been shown in previous studies to act as a fluid microsphere and to be useful in quantitating blood flow in brain, myocardium, and kidneys. In this study we have evaluated this agent as a PET tumor blood flow agent. 64Cu- or 67Cu-labeled Cu-PTSM was administered (i.v.) to Golden Syrian hamsters with colorectal carcinoma cell implants (GW39). One minute prior to sacrifice (10-60 min after Cu-PTSM was administered) 125I-iodoantipyrine (125I-IAP), an agent known to measure tumor blood flow, was administered intravenously by a 3-stage, 1 min ramp infusion. Following sacrifice, samples of tumor and brain were removed (within 40s) and the tumor and brain levels of Cu-PTSM and iodoantipyrine determined. Since the brain uptake of both Cu-PTSM and IAP is perfusion rate limited, the brain was used as a reference organ to normalize tumor levels of the two tracers. The plot of Cu-PTSM versus 125I-IAP tumor/brain ratios showed a good linear correlation (r value of 0.97), suggesting that Cu-PTSM could be used to quantify tumor blood flow. Since the mechanism of Cu-PTSM trapping is likely to be due to glutathione levels in the tissue, and because tumor tissue glutathione levels might vary, the temporal uptake of Cu-PTSM was investigated by PET imaging both the tumor-bearing hamsters and approximately 300 g Copenhagen rats bearing R3227 prostate tumors. The tumors were clearly visualized and the retained copper radioactivity in the tumor was constant over the 30 min imaging period.

A myo-inositol pool utilized for phosphatidylinositol synthesis is depleted in sciatic nerve from rats with streptozotocin-induced diabetes

Peripheral nerve from experimentally diabetic rats exhibits lowered levels of myo-inositol (MI) and decreased incorporation of [3H]MI into phosphatidylinositol (PI). There are indications that diminished PI turnover may be causally related to reduced Na+,K(+)-ATPase activity in diabetic nerve. We have investigated whether a metabolic compartment of MI that is essential for PI synthesis is decreased in this tissue. Sciatic nerve segments from streptozotocin-induced diabetic and age-matched normal rats were incubated in vitro with either 32Pi or [3H]cytidine in the presence of propranolol. This cationic amphiphilic agent redirected nerve phospholipid metabolism to produce enhanced 32P incorporation into PI and decreased labeling of phosphatidylcholine and phosphatidyl-ethanolamine. The accumulation of phosphatidyl CMP (CMP-PA) was also demonstrated by chromatographic and enzymatic means. The incorporation of [3H]cytidine into CMP-PA in normal nerve increased up to 15-fold when 0.6 mM propranolol was present. In diabetic nerve, the liponucleotide incorporated 2- to 3-fold more isotope and was more readily labeled at lower drug concentrations as compared to normal nerve. The buildup of [3H]CMP-PA was reduced in a dose-dependent manner in the presence of MI in the incubation medium at concentrations up to 3 mM. However, if MI was added after liponucleotide accumulation, preformed CMP-PA could not be utilized for PI synthesis. The difference in liponucleotide labeling between normal and diabetic nerve was nearly abolished at 0.3 mM medium MI, a concentration much less than the level of cyclitol in the tissue. These results strongly suggest the presence in nerve of a pool of MI that is not in equilibrium with the bulk of nerve MI and that is preferentially used for PI synthesis. This metabolic compartment is depleted in diabetic nerve but can be readily replenished by exogenous MI and may correspond to the MI pool that has been proposed to be required for the turnover of a portion of tissue PI involved in maintenance of normal Na+,K(+)-ATPase activity.

The macrosatellites of the Toulouse goose: the major tandemly repetitive DNA in the toulouse goose genome

This paper examines the principal classes of repetitive DNA of the Toulouse goose (Anser anser) genome. There are four major classes and they are tandem repeats of less than 200 base pairs (bp). The longest repeat (class A) is 190 bp long and starts with a HinfI site. Class B is 43 bp long, commencing with a FokI site. Classes A and B show no extensive homology to DNA sequences held on a current data base (Genbank) but were confirmed to exist as major repeats in another strain of goose, the Emden goose (Anser anser) genome. Classes C and D are 5-bp repeats of 5' GAGAG 3' and 5' GGGAA 3', respectively. The macrosatellites C and D were compared with a current data base (Genbank) and were found to exist in a variety of other organisms as satellites.

1,2-diacylglycerol content and its arachidonyl-containing molecular species are reduced in sciatic nerve from streptozotocin-induced diabetic rats

The content of 1,2-diacylglycerol (DAG) was determined in sciatic nerves from normal and streptozotocin-induced diabetic rats. In nerves frozen in situ, DAG content was reduced 22% in the proximal region and 77% in the distal region of diabetic nerve, principally because of the loss of associated fat. DAG levels in freshly dissected and desheathed diabetic nerve were decreased from 23 to 30% as compared with normal nerve. Determination of DAG molecular species distribution in desheathed normal nerve indicated that 18:0/20:4 accounted for 34%, 16:0/18:1 for 17%, and several other polyunsaturated fatty acid-containing species for 17% of the total. In diabetic nerve, the quantity of the 18:0/20:4 DAG, species was reduced by 37%, and this drop was 62% of the reduction in all molecular species. The content of the minor species, 16:0/20:4 DAG, was decreased by 48%. Our results suggest that nerve DAG arises in large part from phosphoinositide degradation. Moreover, these results provide support for the hypothesis that reduced Na+,K(+)-ATPase activity in diabetic nerve is a consequence of decreased phosphoinositide turnover, which thereby generates insufficient DAG to maintain a protein kinase C-mediated step necessary for activation of Na+,K(+)-ATPase.