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51.
52.
Evidence for a Reductive Pathway for the Anaerobic Metabolism of Benzoate 总被引:18,自引:6,他引:12 下载免费PDF全文
Evidence is presented for a reductive pathway for the anaerobic metabolism of benzoate by Rhodopseudomonas palustris. 相似文献
53.
Evolutionarily conserved sequences of striated muscle myosin heavy chain isoforms. Epitope mapping by cDNA expression 总被引:12,自引:0,他引:12
A cDNA expression strategy was used to localize amino acid sequences which were specific for fast, as opposed to slow, isoforms of the chicken skeletal muscle myosin heavy chain (MHC) and which were conserved in vertebrate evolution. Five monoclonal antibodies (mAbs), termed F18, F27, F30, F47, and F59, were prepared that reacted with all of the known chicken fast MHC isoforms but did not react with any of the known chicken slow nor with smooth muscle MHC isoforms. The epitopes recognized by mAbs F18, F30, F47, and F59 were on the globular head fragment of the MHC, whereas the epitope recognized by mAb F27 was on the helical tail or rod fragment. Reactivity of all five mAbs also was confined to fast MHCs in the rat, with the exception of mAb F59, which also reacted with the beta-cardiac MHC, the single slow MHC isoform common to both the rat heart and skeletal muscle. None of the five epitopes was expressed on amphioxus, nematode, or Dictyostelium MHC. The F27 and F59 epitopes were found on shark, electric ray, goldfish, newt, frog, turtle, chicken, quail, rabbit, and rat MHCs. The epitopes recognized by these mAbs were conserved, therefore, to varying degrees through vertebrate evolution and differed in sequence from homologous regions of a number of invertebrate MHCs and myosin-like proteins. The sequence of those epitopes on the head were mapped using a two-part cDNA expression strategy. First, Bal31 exonuclease digestion was used to rapidly generate fragments of a chicken embryonic fast MHC cDNA that were progressively deleted from the 3' end. These cDNA fragments were expressed as beta-galactosidase/MHC fusion proteins using the pUR290 vector; the fusion proteins were tested by immunoblotting for reactivity with the mAbs; and the approximate locations of the epitopes were determined from the sizes of the cDNA fragments that encoded a particular epitope. The epitopes were then precisely mapped by expression of overlapping cDNA fragments of known sequence that covered the approximate location of the epitopes. With this method, the epitope recognized by mAb F59 was mapped to amino acids 211-231 of the chicken embryonic fast MHC and the three distinct epitopes recognized by mAbs F18, F30, and F47 were mapped to amino acids approximately 65-92. Each of these epitope sequences is at or near the ATPase active site. 相似文献
54.
55.
Mark Phillippe Trevania Saunders Shrikar Bangalore 《In vitro cellular & developmental biology. Plant》1990,26(4):369-378
Summary The following studies were undertaken to develop a cultured uterine myocyte model which would allow further clarification
of the adrenergic signal transduction mechanisms utilized by these myocytes. After mechanical removal of the endometrium,
rabbit uterine myoctes were isolated by an overnight enzymatic disaggregation using collagenase and DNase I. The isolated
myocytes were maintained in culture in 75-cm2 flasks containing Waymouth's MB 751/1 medium-10% fetal bovine serum along with 10−8
M estradiol, penicillin, streptomycin, and Fungizone. The phase contrast and electron micrographic appearance of these cells
was consistent with that previously reported for smooth muscle myocytes in culture. Immunocytochemical studies utilizing monoclonal
anti-alpha-smooth muscle actin antibodies confirmed the presence of smooth muscle actin in these cultured myocytes. Western
blot studies similarly confirmed the presence of alpha-smooth muscle actin in rabbit myometrial tissue and the cultured myocytes,
both the primary and F1 generation. After prelabeling the myocytes with [3H]inositol, adrenergic stimulation experiments demonstrated alpha-1 receptor mediated stimulation of inositol phosphates.
Beta receptor stimulation experiments confirmed cAMP production in these cultured myocytes, and the ability of clonidine,
an alpha-2 agonist, to inhibit forskolin stimulated cAMP production confirmed the presence of functional alpha-2 adrenergic
receptors in these myocytes. In conclusion, these cultured rabbit uterine myocytes have provided an in vitro model which can
be utilized to further clarify the adrenergic receptor signal transduction mechanisms in genital tract smooth muscle.
This research was supported by grant HD-22063 from the National Institutes of Health, Bethesda, MD. 相似文献
56.
57.
Benjamin B. Roa Frank Greenberg Preethi Gunaratne Christine M. Sauer Mark S. Lubinsky Chahira Kozma Jeanne M. Meck R. Ellen Magenis Lisa G. Shaffer J. R. Lupski 《Human genetics》1996,97(5):642-649
Autosomal dominant Charcot-Marie-Tooth type-1A neuropathy (CMT1A) is a demyelinating peripheral nerve disorder that is commonly
associated with a submicroscopic tandem DNA duplication of a 1.5-Mb region of 17p11.2p12 that contains the peripheral myelin
gene PMP22. Clinical features of CMT1A include progressive distal muscle atrophy and weakness, foot and hand deformities, gait abnormalities,
absent reflexes, and the completely penetrant electrophysiologic phenotype of symmetric reductions in motor nerve conduction
velocities (NCVs). Molecular and fluorescence in situ hybridization (FISH) analyses were performed to determine the duplication
status of the PMP22 gene in four patients with rare cytogenetic duplications of 17p. Neuropathologic features of CMT1A were seen in two of these
four patients, in addition to the complex phenotype associated with 17p partial trisomy. Our findings show that the CMT1A
phenotype of reduced NCV is specifically associated with PMP22 gene duplication, thus providing further support for the PMP22 gene dosage mechanism for CMT1A.
Received: 3 May 1995 / Revised: 1 August 1995 相似文献
58.
To gain insight into the evolution of rodent major histocompatibility complex (MHC) class I genes and identify important (conserved) nonclassical class I (class Ib) gene products and residues in these proteins,
sixPeromyscus maniculatus MHC (Pema) class I cDNA clones were isolated and sequenced. FivePema class I cDNAs appeared most similar to mouse and rat classical class I (class Ia) genes. One exhibited highest similarity
to anH2 class Ib gene,H2-T23 (encoding the Qa1 antigen). Phylogenetic trees constructed withPema, RT1, andH2 class I sequences suggested that the lineages of some rodent class Ib genes (e.g.,T23 andT24) originated prior toMus andPeromyscus speciation [>50 million years (My) ago]. Sequences of four Qa1-like proteins from three species permitted the identification
of ten Qa1-specific amino acids. On the basis of molecular modeling, three residues showed the potential to interact with
T-cell receptors and three residues (all corresponding to polymorphic positions among H2 class Ia proteins) were predicted
to influence antigen binding. The recognition of mouse Qa1 proteins by a subset of T-cells in influenced by a locus,Qdm, which encodes the H2-D leader peptide. One of thePema class I cDNA clones classified asH2-K, D/L-like (class Ia) is predicted to encode an identical peptide, implying that an antigen binding protein (Qa1) and the antigen
to which it binds (the product ofQdm) has been conserved for over 50 My.
The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide sequence database and have
been assigned the accession numbers U12822 (Pm13), U12885 (Pm41), U12886 (Pm52), U12887 (Pm62), U16846 (Pm11), and U16847 (Pm53) 相似文献
59.
A new major histocompatibility complex class I b gene expressed in the mouse blastocyst and placenta
Susan L. Sipes Maxine V. Medaglia Deborah L. Stabley Craig S. DeBruyn Mark S. Alden Vicki Catenacci C. P. Landel 《Immunogenetics》1996,45(2):108-120
Because of the role major histocompatibility complex (MHC) class I b molecules may play during mouse embryonic development,
we thought it would be interesting to search for additional MHC class I b molecules that might be expressed in preimplantation
embryos, and in particular in the trophoblastic lineage. We therefore screened a mouse preimplantation blastocyst cDNA library
for MHC class I sequences. This search led to the identification and characterization of a new MHC class I b gene, blastocyst MHC. Sequences identical to the exons and 3′ untranslated region of this gene have been found in many laboratory mouse strains,
as well as in the related mouse species Mus spreciligus. The presence of this gene in mouse strains of different MHC class I haplotypes argues that blastocyst MHC is a unique, newly-described gene rather than a new allele of a previously described mouse MHC class I gene. Blastocyst MHC has the structure of an MHC class I b gene, with the six exons characteristic of T-region genes. It is linked to H2-D. The amino acid sequence encoded by this gene maintains all the features of a functional antigen-presentation domain. The
blastocyst MHC gene, like the human class I b gene HLA-G, is expressed at the blastocyst stage and in the placenta, and may be the mouse analog for HLA-G.
Received: 31 May 1996 / Revised: 19 August 1996 相似文献
60.
Mark T. Strong 《Brittonia》1996,48(1):96-99
Bulbostylis splendens from Brazil is described, illustrated, and compared to a related taxon. 相似文献