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21.
Class I major histocompatibility complex cDNA clones from sheep thymus: alternative splicing could make a long cytoplasmic tail 总被引:4,自引:4,他引:0
To investigate the class I major histocompatibility complex (MHC) genes expressed in the young sheep thymus, a cDNA library was screened with a human HLA-B7 cDNA probe under conditions of relaxed stringency. Thirteen clones were isolated and found by partial sequences to fall into five classes, requiring the expression of at least three loci. One sequence was found six times, almost half of the total, and may thus represent the major message expressed in the young sheep thymus. One of the clones was found to have failed to excise the intron between cytoplasmic exons 7 and 8, leading to the predicted synthesis of a cytoplasmic domain 23 amino acids longer than the other sheep sequences, and 15 amino acids longer than any cytoplasmic domain previously described. The sequences of all the clones were found to be most similar to bovine, and least similar to mouse class I MHC sequences.The nucleotide sequence data reported in this paper have been sunmitted to the GenBank nucleotide sequence database and have been assigned the accession numbers M 34672-6. 相似文献
22.
23.
John F. Reinhard Jr. Emanuel J. Diliberto Jr. Alejandro J. Daniels 《Journal of neurochemistry》1989,52(4):1253-1259
Cultures of bovine adrenomedullary chromaffin cells accumulated 1-[methyl-3H]methyl-4-phenylpyridinium ([3H]MPP+) in a time- and concentration-dependent manner with an apparent Km of 0.7 microM and a Vmax of 3 pmol/min/10(6) cells. The uptake was sodium dependent and sensitive to inhibitors of the cell-surface catecholamine transporter. At low concentrations of MPP+, the subcellular distribution was identical to that of endogenous catecholamines in the catecholamine-containing chromaffin vesicles. However, at a higher concentration of MPP+, a larger proportion of the toxicant was recovered in the cytosolic fraction, with less in the chromaffin vesicle fractions. When cells were prelabeled with [3H]MPP+, at 1 and 300 microM, and then permeabilized with digitonin in the absence of Ca2+, there was a proportionally greater release of MPP+ from the cells labeled at the higher concentration of the toxicant. In the presence of Ca2+, cell permeabilization induced a time-dependent secretion of catecholamines and a parallel secretion of MPP+. Under these conditions, the secretion of endogenous catecholamines was unaffected by the presence of MPP+. When the permeabilization studies were carried out in the presence of tetrabenazine, a massive release of MPP+ was observed in the absence of Ca2+ and was not further increased by Ca2+. In intact cells prelabeled with 300 microM [3H]MPP+, the secretagogues nicotine and veratridine elicited a Ca2+ -dependent secretion of catecholamines and MPP+ from the cells in similar proportions to their cellular contents. Barium-induced release of both species was independent of external Ca2+.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
24.
Maria Claudia Gonzalez Deniselle Susana L. Gonzalez Gerardo G. Piroli Analia E. Lima Alejandro F. De Nicola 《Cellular and molecular neurobiology》1996,16(1):61-72
Summary 1. Wobbler mice suffer an autosomal recessive mutation producing severe motoneuron degeneration and dense astrogliosis, with
increased levels of glial fibrillary acidic protein (GFAP) in the spinal cord and brain stem. They have been considered animal
models of amyotrophic lateral sclerosis and infantile spinal muscular atrophy.
2. Using Wobbler mice and normal littermates, we investigated the effects of the membrane-active steroid Lazaroid U-74389F
on the number of GFAP-expressing astrocytes and glucocorticoid receptors (GR). Lazaroids are inhibitors of oxygen radical-induced
lipid peroxidation, and proved beneficial in cases of CNS injury and ischemia.
3. Four days after pellet implantation of U-74389F into Wobbler mice, hyperplasia and hypertophy of GFAP-expressing astrocytes
were apparent in the spinal cord ventral and dorsal horn, areas showing already intense astrogliosis in untreated Wobbler
mice. In control mice, U-74389F also produced astrocyte hyperplasia and hypertophy in the dorsal horn and hyperplasia in the
ventral-lateral funiculi of the cord.
4. Givenin vivo U-74389F did not change GR in spinal cord of Wobbler or control mice, in line with the concept that it is active in membranes
but does not bind to GR. Besides, U-74390F did not compete for [3H]dexamethasone binding when addedin vitro.
5. The results suggest that stimulation of proliferation and size of GFAP-expressing astrocytes by U-74389F may be a novel
mechanism of action of this compound. The Wobbler mouse may be a valuable animal model for further pharmacological testing
of glucocorticoid and nonglucocorticoid steroids in neurodegenerative diseases. 相似文献
25.
Socorro Durán Luis Sánchez-Linares Alejandro Huerta-Saquero Gisela Du Pont Alejandra Huerta-Zepeda Jorge Calderón 《Biochemical genetics》1996,34(11-12):453-465
We present evidence thatRhizobium etli has two glutaminases differentiated by their thermostability and electrophoretic mobility. The thermostable glutaminase (B) is constitutive, in contrast with the thermolabile glutaminase (A), which is positively regulated by glutamine and negatively regulated by ammonium and by the carbon source. In distinction to glutaminase A, glutaminase B plays a minor role in the utilization of glutamine as a carbon source, but it may play a role in maintaining the balance of glutamine and glutamate. By complementation of theRhizobium etli LM16 mutant that lacks glutaminase A, we have cloned the gene that codes for this enzyme. 相似文献
26.
Alejandro Lynch Allan J. Baker 《Evolution; international journal of organic evolution》1994,48(2):351-359
We investigated cultural evolution in populations of common chaffinches (Fringilla coelebs) in the Atlantic islands (Azores, Madeira, and Canaries) and neighboring continental regions (Morocco and Iberia) by employing a population-memetic approach. To quantify differentiation, we used the concept of a song meme, defined as a single syllable or a series of linked syllables capable of being transmitted. The levels of cultural differentiation are higher among the Canaries populations than among the Azorean ones, even though the islands are on average closer to each other geographically. This is likely the result of reduced levels of migration, lower population sizes, and bottlenecks (possibly during the colonization of these populations) in the Canaries; all these factors produce a smaller effective population size and therefore accentuate the effects of differentiation by random drift. Significant levels of among-population differentiation in the Azores, in spite of substantial levels of migration, attest to the differentiating effects of high mutation rates of memes, which allow the accumulation of new mutants in different populations before migration can disperse them throughout the entire region. 相似文献
27.
Dario Maestripieri 《Primates; journal of primatology》1994,35(4):443-453
Data from over 400 hr of observation of mother-infant rhesus macaques indicate that during the first 12 weeks of lactation
infants are at risk from other group members and that mothers use aggression as well as restraining to protect them. Maternal
aggression was negatively correlated with infant restraining. High-ranking mothers reacted aggressively to individuals handling
their infants more than did middle- and low-ranking mothers. Conversely, middle- and low-ranking mothers restrained their
infants more than did high-ranking mothers. Maternal aggression did not vary with infant age. Maternal aggression was directed
toward a higher proportion of higher-ranking adult females and their immature offspring and was more likely to be followed
by counter-aggression than nonmaternal aggression, i.e. aggression not related to interactions involving the infant. Middle-and
low-ranking mothers suffered higher costs in terms of retaliation than high-ranking mothers. It is argued that the occurrence
and distribution of maternal aggression among species and individuals should depend on the risk posed to infants by conspecifics
as well as on the characteristics of the social structure (e.g. degree of asymmetry of agonistic contests) and of the mother
(e.g. her dominance rank) which may affect the probability of retaliation. 相似文献
28.
The nucleotide data reported in this paper have been submitted to the GenBank nucleotide sequence database and have been assigned the accession number L22178. 相似文献
29.
Nathalie Leduc Victor Alejandro Iglesias Roland Bilang Andreas Gisel Ingo Potrykus Christof Sautter 《Sexual plant reproduction》1994,7(2):135-143
Direct gene transfer to floral meristems could contribute to cell-fate mapping, to the study of flower-specific genes and promoters, and to the production of transgenic gametes via the transformation of sporogenic tissues. Despite the wide potential of its applications, direct gene transfer to floral meristems has not been achieved so far because of the lack of suitable technology. We show in this paper that ballistic micro-targeting is the technique of choice for this purpose, and in this way, we were able to transfer genes efficiently into excised wheat immature spikes. Particle size was adjusted for optimal penetration into the L1 and L2 cell layers of the spikes with limited cell damage. Spikes at different developmental stages were shot either with a plasmid containing two genes involved in anthocyanin biosynthesis or with a plasmid bearing the uidA (-glucuronidase) gene. The transient expression of these marker genes was observed in the different developmental stages tested and in cells of both the L1 and the L2 layers. The transient expression of the uidA gene was significantly increased when the sucrose concentration in the culture medium was increased from 0.06 to 0.52 M. At the highest concentration, 100% of the targeted spikes expressed the uidA gene, with an average of 69 blue cells per spike. Twelve days after microtargeting, multicellular sectors showing transgene expression and containing up to 17 cells were found in 85% of the shot immature inflorescences. This indicated that targeted cells survived particle bombardment. Sectors were found in primordia of both vegetative and reproductive organs. 相似文献
30.
Dario Grossberger Anne Marcuz Annette Fichtel Lisbeth Dudler Wayne R. Hein 《Immunogenetics》1993,37(3):222-226
The nucleotide sequences reported in this paper have been submitted to the GenBank database and have been assigned the accession numbers M94181-M94183. 相似文献