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1.
Opiate receptors have been identified within the striatum and some have been localized presynaptically to nigrostriatal neurons. Using unilateral ablative lesions of the substantia nigra, we examined binding in the ipsilateral and contralateral striata. Lesions significantly lowered both 3H[D-Ala2,MePhe4,Gly(ol)5]enkephalin (DAGO) and 3H[D-Ala2,Leu5]enkephalin (DADL) binding. The inclusion of competitors in these assays revealed a decrease in both mu1 and mu2 receptors. Mu1 binding was slightly more sensitive to the lesioning than mu2 binding. Selective mu1 and mu2 binding assays supported these observations. No change in delta binding was observed in the lesioned striata. These studies raise the possibility that both mu1 and mu2, but not delta, receptors are localized presynaptically on nigrostriatal neurons. 相似文献
2.
Phylogenetic distribution in the genus Mus of t-complex-specific DNA and protein markers: inferences on the origin of t-haplotypes 总被引:8,自引:0,他引:8
Delarbre C; Kashi Y; Boursot P; Beckmann JS; Kourilsky P; Bonhomme F; Gachelin G 《Molecular biology and evolution》1988,5(2):120-133
We have examined the phylogenetic distribution of two t-specific markers
among representatives of various taxa belonging to the genus Mus. The
centromeric TCP-1a marker (a testicular protein variant specific for all
t-haplotypes so far studied) has also been apparently detected in several
non-t representatives of the Mus IVA, Mus IVB, and probably M. cervicolor
species. By contrast, a t-specific restriction- fragment-length
polymorphism allele (RFLP) of the telomeric alpha- globin pseudogene DNA
marker alpha-psi-4 was found only in animals belonging to the M.
musculus-complex species either bearing genuine t- haplotypes or, like the
M. m. bactrianus specimen studied here, likely to do so. This t-specific
alpha-psi-4 RFLP allele was found to be as divergent from the RFLP alleles
of the latter, non-t, taxonomical groups as it is from Mus 4A, Mus 4B, or
M. spretus ones. These results suggest the presence of t-haplotypes and of
t-specific markers in populations other than those belonging to the M. m.
domesticus and M. m. musculus subspecies, implying a possible origin for
t-haplotypes prior to the radiation of the most recent offshoot of the Mus
genus (i.e., the spretus/domesticus divergence), some 1-3 Myr ago.
相似文献
3.
Mark A. Wolters Mary E. Bodnar Mary D. Strem Scott E. Bingham 《Applied microbiology and biotechnology》1991,35(1):56-59
Summary In order to deregulate arginine biosynthesis in Synechococcus sp. PCC7942, d-arginine-resistant cell lines were selected following ethyl methanesulfonate mutagenesis of wild-type (WT) cells. Three of these arginine-producing mutant (APM) cell lines, APM1, APM31 and APM40, were putative regulatory mutants based upon secretion of l-arginine into their growth medium. HPLC of lyophilized post-harvest supernatants of APM 31 and 40 resolved two predominant amino acids, arginine and citrulline. In-vitro activity of N-acetylglutamate kinase (NAGK), the proposed regulatory enzyme of the arginine pathway, was about 100-fold less sensitive to l-arginine inhibition in extracts from APM 31 and 40 than the enzyme in WT extracts. The enzyme from APM 1 was 20-fold less sensitive to l-arginine inhibition than WT. The most likely site of mutation in each of the APM cell lines is in the gene for NAGK, rendering the enzymes insensitive to l-arginine feedback control. These strains can be utilized for the phototrophic production of arginine.
Offprint requests to: S. E. Bingham 相似文献
4.
The contractile basis of amoeboid movement: V. The control of gelation, solation, and contraction in extracts from dictyostelium discoideum 总被引:29,自引:22,他引:7
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Motile extracts have been prepared from Dictyostelium discoideum by homogenization and differential centrifugation at 4 degrees C in a stabilization solution (60). These extracts gelled on warming to 25 degrees Celsius and contracted in response to micromolar Ca++ or a pH in excess of 7.0. Optimal gelation occurred in a solution containing 2.5 mM ethylene glycol-bis (β-aminoethyl ether)N,N,N',N'-tetraacetate (EGTA), 2.5 mM piperazine-N-N'-bis [2-ethane sulfonic acid] (PIPES), 1 mM MgC1(2), 1 mM ATP, and 20 mM KCI at ph 7.0 (relaxation solution), while micromolar levels of Ca++ inhibited gelation. Conditions that solated the gel elicited contraction of extracts containing myosin. This was true regardless of whether chemical (micromolar Ca++, pH >7.0, cytochalasin B, elevated concentrations of KCI, MgC1(2), and sucrose) or physical (pressure, mechanical stress, and cold) means were used to induce solation. Myosin was definitely required for contraction. During Ca++-or pH-elicited contraction: (a) actin, myosin, and a 95,000-dalton polypeptide were concentrated in the contracted extract; (b) the gelation activity was recovered in the material sqeezed out the contracting extract;(c) electron microscopy demonstrated that the number of free, recognizable F-actin filaments increased; (d) the actomyosin MgATPase activity was stimulated by 4- to 10-fold. In the absense of myosin the Dictyostelium extract did not contract, while gelation proceeded normally. During solation of the gel in the absense of myosin: (a) electron microscopy demonstrated that the number of free, recognizable F- actin filaments increased; (b) solation-dependent contraction of the extract and the Ca++-stimulated MgATPase activity were reconstituted by adding puried Dictyostelium myosin. Actin purified from the Dictyostelium extract did not gel (at 2 mg/ml), while low concentrations of actin (0.7-2 mg/ml) that contained several contaminating components underwent rapid Ca++ regulated gelation. These results indicated : (a) gelation in Dictyostelium extracts involves a specific Ca++-sensitive interaction between actin and several other components; (b) myosin is an absolute requirement for contraction of the extract; (c) actin-myosin interactions capable of producing force for movement are prevented in the gel, while solation of the gel by either physical or chemical means results in the release of F-actin capable of interaction with myosin and subsequent contraction. The effectiveness of physical agents in producting contraction suggests that the regulation of contraction by the gel is structural in nature. 相似文献
5.
Characterization of the integral membrane polypeptides of rat liver peroxisomes isolated from untreated and clofibrate-treated rats. 总被引:11,自引:0,他引:11
We have characterized the integral membrane polypeptides of liver peroxisomes from untreated rats and rats treated with clofibrate, a peroxisome proliferator. Membranes, prepared by treatment of purified peroxisomes with sodium carbonate, were used to raise an antiserum in rabbits. Immunoblot analysis demonstrated the reaction of this antiserum with six peroxisomal integral membrane polypeptides (molecular masses, 140, 69, 50, 36, 22, and 15 kDa). Treatment of rats with the hypolipidemic drug clofibrate caused a 4- to 10-fold induction in the 69-kDa integral membrane polypeptide, while the other integral membrane polypeptides remained unchanged or varied to a lesser extent. The anti-peroxisomal membrane serum reacted with two integral membrane polypeptides of the endoplasmic reticulum which co-migrated with the 50- and 36-kDa integral membrane polypeptides of the peroxisome. Biochemical and immunoblot analyses indicated that these integral membrane polypeptides were co-localized to peroxisomes and endoplasmic reticulum. Immunoprecipitation of in vitro translation products of RNA isolated from free and membrane-bound polysomes indicated that the 22-, 36-, and 69-kDa integral membrane polypeptides were synthesized on free polysomes, while the 50-kDa integral membrane polypeptide was predominantly synthesized on membrane-bound polysomes. The predominant synthesis of the 50-kDa integral membrane polypeptide on membrane-bound polysomes raises interesting possibilities concerning its biosynthesis. 相似文献
6.
The observation that increased muscular activity leads to muscle hypertrophy is well known, but identification of the biochemical and physiological mechanisms by which this occurs remains an important problem. Experiments have been described (5, 6) which suggest that creatine, an end product of contraction, is involved in the control of contractile protein synthesis in differentiating skeletal muscle cells and may be the chemical signal coupling increased muscular activity and the increased muscular mass. During contraction, the creatine concentration in muscle transiently increases as creatine phosphate is hydrolyzed to regenerate ATP. In isometric contraction in skeletal muscle for example, Edwards and colleagues (3) have found that nearly all of the creatine phosphate is hydrolyzed. In this case, the creatine concentration is increased about twofold, and it is this transient change in creatine concentration which is postulated to lead to increased contractile protein synthesis. If creatine is found in several intracellular compartments, as suggested by Lee and Vissher (7), local changes in concentration may be greater then twofold. A specific effect on contractile protein synthesis seems reasonable in light of the work of Rabinowitz (13) and of Page et al. (11), among others, showing disproportionate accumulation of myofibrillar and mitochondrial proteins in response to work-induced hypertrophy and thyroxin-stimulated growth. Previous experiments (5, 6) have shown that skeletal muscles cells which have differentiated in vitro or in vivo synthesize myosin heavy-chain and actin, the major myofibrillar polypeptides, faster when supplied creatine in vitro. The stimulation is specific for contractile protein synthesis since neither the rate of myosin turnover nor the rates of synthesis of noncontractile protein and DNA are affected by creatine. The experiments reported in this communication were undertaken to test whether creatine selectively stimulates contractile protein synthesis in heart as it does in skeletal muscle. 相似文献
7.
A domain model for eukaryotic DNA organization: a molecular basis for cell differentiation and chromosome evolution 总被引:7,自引:0,他引:7
J W Bodnar 《Journal of theoretical biology》1988,132(4):479-507
A model for eukaryotic chromatin organization is presented in which the basic structural and functional unit is the DNA domain. This simple model predicts that both chromosome replication and cell type-specific control of gene expression depend on a combination of stable and dynamic DNA-nuclear matrix interactions. The model suggests that in eukaryotes, DNA regulatory processes are controlled mainly by the intranuclear compartmentalization of the specific DNA sequences, and that control of gene expression involves multiple steps of specific DNA-nuclear matrix interactions. Predictions of the model are tested using available biochemical, molecular and cell biological data. In addition, the domain model is discussed as a simple molecular mechanism to explain cell differentiation in multi-cellular organisms and to explain the evolution of eukaryotic genomes consisting mainly of repetitive sequences and "junk" DNA. 相似文献
8.
Recent neuroanatomical and behavioral evidence has indicated that vasopressin (VP) increases pain thresholds. In the present study intracerebroventricular (ICV) administration of both arginine VP (AVP: 75-500 ng) and 1-deamino-8-D-arginine vasopressin (DDAVP: 150-500 ng) elevated tail flick latencies. Oxytocin (OXY, ICV), also elevated tail-flick latencies (150-1000 ng); however this increase was accompanied by "barrel-roll" seizure activity. VP analgesia was eliminated by pretreatment with 1-deamino-penicillamine-2(O-methyl)tyrosine-AVP (dPTyr(me)AVP: 500 ng, ICV), a VP antagonist, but not naloxone (1 or 10 micrograms, ICV), suggesting that VP modulates nonciceptive thresholds through its own binding sites. Conversely, pretreatment with naloxone (1 micrograms, ICV) but not dPTyr(me)AVP (1 microgram, ICV) attenuated the analgesic efficacy of systemic morphine (10 mg/kg), further dissociating VP and central opiate analgesic processes. Finally, systemic pretreatment with dexamethasone potentiated VP analgesia. These data support the notion that VP is a specific non-opioid pain inhibitor. 相似文献
9.
The results described in the accompanying article support the model in
which glucosylphosphoryldolichol (Glc-P-Dol) is synthesized on the
cytoplasmic face of the ER, and functions as a glucosyl donor for three
Glc-P-Dol:Glc0-2Man9-GlcNAc2-P-P-Dol glucosyltransferases (GlcTases) in the
lumenal compartment. In this study, the enzymatic synthesis and structural
characterization by NMR and electrospray-ionization tandem mass
spectrometry of a series of water-soluble beta-Glc-P-Dol analogs containing
2-4 isoprene units with either the cis - or trans - stereoconfiguration in
the beta-position are described. The water- soluble analogs were (1) used
to examine the stereospecificity of the Glc-P-Dol:Glc0-2Man9GlcNAc2-P-P-Dol
glucosyltransferases (GlcTases) and (2) tested as potential substrates for
a membrane protein(s) mediating the transbilayer movement of Glc-P-Dol in
sealed ER vesicles from rat liver and pig brain. The Glc-P-Dol-mediated
GlcTases in pig brain microsomes utilized [3H]Glc-labeled Glc-P-Dol10,
Glc-P-(omega, c )Dol15, Glc-P(omega, t,t )Dol20, and Glc-P-(omega, t,c
)Dol20as glucosyl donors with [3H]Glc3Man9GlcNAc2-P-P-Dol the major product
labeled in vitro. A preference was exhibited for C15-20 substrates
containing an internal cis -isoprene unit in the beta-position. In
addition, the water-soluble analog, Glc-P-Dol10, was shown to enter the
lumenal compartment of sealed microsomal vesicles from rat liver and pig
brain via a protein-mediated transport system enriched in the ER. The
properties of the ER transport system have been characterized. Glc-
P-Dol10was not transported into or adsorbed by synthetic PC-liposomes or
bovine erythrocytes. The results of these studies indicate that (1) the
internal cis -isoprene units are important for the utilization of Glc-P-Dol
as a glucosyl donor and (2) the transport of the water- soluble analog may
provide an experimental approach to assay the hypothetical "flippase"
proposed to mediate the transbilayer movement of Glc-P-Dol from the
cytoplasmic face of the ER to the lumenal monolayer.
相似文献
10.
A MicroRNA Cluster miR‐23–24–27 Is Upregulated by Aldosterone in the Distal Kidney Nephron Where it Alters Sodium Transport
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