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991.
Rubén C. Aguilar Lilia A. Retegui Marie-Catherine Postel-Vinay Leonor P. Roguin 《Molecular and cellular biochemistry》1994,136(1):35-42
We have previously shown that a monoclonal antibody (MAb) recognizing the human growth hormone (hGH) antigenic domain left exposed after binding to lactogenic receptors enhanced hGH binding probably through allosteric effects on the hormone binding site. Since receptors displaying different specificities would not recognize exactly the same hGH region, we explored whether some of our MAb could affect hGH binding to somatogenic receptors from rabbit liver and to human liver hGH-specific receptors.The effect of MAbAE5, AC8 and F11 on hGH binding was measured by determining the formation of125I-MAb:hGH:receptor complexes using two different experimental approaches. Results from procedure A, which involved the previous binding of the hormone to microsomes before adding125I-MAb, indicated that the hGH domain defined by epitopes AE5, AC8 and F11 is uncovered in the various hormone:receptor complexes.Procedure B was devised to reveal any alteration in the hGH molecule induced by the MAb. In this case preformed125I-MAb:hGH complexes were added to microsomes. Data showed that125I-MAb AE5:hGH complexes bound better to the various receptors than125I-MAb AE5 to hGH:receptor complexes. On the contrary, hGH previously bound to125I-MAb AC8 or125I-MAb F11 was less recognized by the receptors than the free hormone. Furthermore, binding of MAb AE5 or MAb F11 to hGH 20 K (a natural hGH variant lacking residues 32–46) also enhanced its affinity to the various receptors whereas MAb AC8 did not inhibit hGH 20 K binding.Results indicated that MAb recognizing the hGH antigenic area that remains unmasked after binding to different membrane-bound receptors are able to affect hormone binding site. MAb would induce either positive or negative allosteric changes in the hormone region involved in its binding to lactogenic, somatogenic and hGH-specific receptors. 相似文献
992.
Antibodies directed against different visual pigment opsins, and an antibody raised against the C terminal of the -subunit of retinal G protein (transducin) labelled cerebrospinal fluid-contacting cells located within the hypothalamus (postoptic commissural nucleus and ventral hypothalamic nucleus) of ammocoete lampreys (Petromyzon marinus). These antibodies also labelled photoreceptor cells within the retina and the pineal and parapineal organs, but no other areas of the brain. Despite considerable behavioural and physiological evidence for the existence of deep brain photoreceptors, numerous studies have failed to identify photoreceptor proteins within the basal brain. The results presented in this paper support our recent results in the lizard Anolis carolinensis, suggesting that a group of cerebrospinal fluid-contacting neurons within the vertebrate brain have a photosensory capacity. We speculate that these cells mediate extraocular and extrapineal photoreception in nonmammalian vertebrates. 相似文献
993.
Serotonin- and ten peptide-immunoreactive (IR) cell types were identified in the digestive tract of sea bass (Dicentrarchus labrax L.) larvae of four morphofunctional phases ranging in age from hatching to 61 days. The sequence of appearance and location of endocrine cells during ontogenetic development of the larvae was determined. The differentiation of endocrine cells followed a distal-proximal gradient in the gut which paralleled the morphofunctional differentiation. Serotonin-IR cells were identified in the last portion of the digestive tract from phase I onwards and in the gastric region from phase III, before these regions were morphofunctionally differentiated; met-enkephalin-IR cells were identified from phase II onwards in both the differentiated rectum and the undifferentiated intestine; cholecystokinin (CCK)- and synthetic human gastrin-34-IR cells were located only in the intestine and first found in the undifferentiated intestine of phase II; human gastrin-17-, peptide YY (PYY)- and neuropeptide Y (NPY)-IR cells appeared in the intestine from phase II and in stomach in phase IV, when it showed gastric glands; pancreatic polypeptide (PP)- and glucagon-IR cells were observed in both intestine and stomach, but insulin- and somatostatin-IR cells only in stomach, from phase III, during which the intestine but not the stomach was differentiated. PP- and PYY-, PP- and glucagon-, and PYY- and glucagon-like immunoreactivities coexisted from their first appearance in some cells of the gut. 相似文献
994.
Mariam Lebbadi Antonio Gálvez Eva Valdivia Manuel Martínez-Blueno Mercedes Maqueda 《Archives of microbiology》1994,162(1-2):98-102
Three antibiotic peptides with amoebolytic activity have been purified from culture supernatants of Bacillus licheniformis M-4 (amoebicins m4-A, m4-B, and m4-C). They were hydrophilic peptides consisting of six different amino acids (Asp, Glu, Ser, Thr, Pro, Tyr). Their molecular weights ranged from 3,000 to 3,200. Purified amoebicins were active against human pathogenic and non-pathogenic strains of Naegleria. They also showed a broad antifungal spectrum, but a narrow antibacterial activity.Abbreviations (TFA)
Trifluoroacetic acid 相似文献
995.
J. Haplová V. Farkaš M. Hejtmánek R. Koďousek J. Malínský 《Archives of microbiology》1994,161(4):340-344
Rylux BSU, a new fluorescent brightener from the family of 4,4-diaminostilbene-2,2disulfonic acid derivatives, inhibited growth and cytokinesis of the yeast Saccharomyces cerevisiae. In the presence of 0.1–1 mg/ml Rylux BSU the cells grew in clumps, had irregular shape and were larger than controls. They formed apparently normal primary septa but their secondary septa and lateral cell walls, especially those in older cells, were abnormally thick with large deposits of amorphous wall material in the periplasmic spaces all over the cell surface. Chitin content in the cell walls of cells grown in the presence of Rylux BSU was increased 2 to 5 times in comparison to that of the controls and glucan content was reduced by up to 30%. In the in vitro assays with particulate membrane fractions, Rylux BSU acted as a non-competitive inhibitor of -1,3-glucan synthase with inhibitory constant K
i=1.75 mg/ml whereas the chitin synthase was inhibited to a much lesser extent. From the difference of the effects of Rylux BSU on the synthesis of chitin in vivo and in vitro it is concluded that the brightener interacts with chitin synthase only indirectly, possibly by influencing the properties of integral plasma membrane.Abbreviations RBSU
Rylux BSU, 1,4-benzenedisulfonic acid-2,2-[ethyleneidy]bis[(3-sulpho-4,1-phenylene)imino[6-bis(2-hydroxyethyl)amino]-1,3,5-triazine-4,2-diylamino]]bis-, hexasodium salt
- FB
fluorescent brightener 相似文献
996.
Golgi-Cox-stained bipolar cells of the medial superior olive (MSO) were analyzed in control and undernourished Wistar strain rats at 12, 20, 30 and 40 days of age. Undernutrition significantly reduced the number of dendrites and the extension of ipsilateral dendritic prolongations, with no effects upon the cross-sectional somal area and minimal alterations in the corresponding contralateral dendritic branches. The data suggest that in underfed rate, afferents from the receptors projecting to the MSO via the anteroventral cochlear nuclei may cause an imblance in the binaural interactions which occur between the axon terminals and the ipsilateral contralateral dendritic arbors of MSO neurons. 相似文献
997.
Enrique Cerdá-Olmedo Rafael Fernández-Martín Javier Ávalos 《Antonie van Leeuwenhoek》1994,65(3):217-225
Gibberella fujikuroi (Fusarium moniliforme) is a complex group of plant pathogens. Some strains produce gibberellic acid and other gibberellins that promote growth and regulate various stages in plant development.The paper describes the research effort directed to development of genetic tools for this species. Furthermore the main features of the gibberellin biosynthetic pathway as established in Gibberella are described.Abbreviations AMO 1618
2-isopropyl-4-(trimethylammonium chloride)-5-methylphenylpiperidine-1-carboxylate
- hydroxykaurenoic acid
ent-kaur-16-en-7-ol-19-oic acid
- kaurenal
ent-kaur-16-en-19-al
- kaurene
ent-kaur-16-ene
- kaurenoic acid
ent-kaur-16-en-19-oic acid
- kaurenol
ent-kaur-16-en-19-ol
- paclobutrazol
1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-lyl)pentan-3-ol
- pefurazoate
pent-4-enyl-N-furfuryl-N-imidazol-1-ylcarbonyl-DL-homoa laninate
- tetcyclacis
5-(4-chlorophenyl)-3,4,5,9,10-pentaazatetracyclo-5,4,102.6,O8.11-dodeca-3,9-diene
- triarimol
-(2,4-dichlorophenyl)--phenyl-5-pyrimidine methyl alcohol 相似文献
998.
999.
Juan Núez-Farfn Rodolfo Dirzo 《Evolution; international journal of organic evolution》1994,48(2):423-436
It has been assumed that herbivores constitute a selective agent for the evolution of plant resistance. However, few studies have tested this hypothesis. In this study, we look at the annual weed Datura stramonium for evidence of current natural selection for resistance to herbivorous insects. Paternal half-sib families obtained through controlled crosses were exposed to herbivores under natural conditions. The plants were damaged by two folivorous insects: the tobacco flea beetle Epitrix parvula and the grasshopper Sphenarium purpurascens. Selection was estimated using a multiple-regression analysis of plant size and of damage by the two herbivores on plant fitness measured as fruit production for both individual phenotypes and family breeding values (genetic analysis). Directional phenotypic selection was detected for both larger plant size and lower resistance to the flea beetles, whereas stabilizing phenotypic selection was revealed for resistance to S. purpurascens. However, performing the same analyses on the breeding values of the characters revealed directional and stabilizing selection only for plant size. Thus, no agreement existed between the results of the two types of analyses, nor was there any detectable potential for genetic change in the studied population because of selection on herbivore resistance. The narrow-sense heritability of every trait studied was small (all <0.1) and not different from zero. The potential for evolutionary response to natural selection for higher resistance to herbivores in the studied population of D. stramonium is probably limited by lack of genetic variation. Natural selection acts on phenotypes, and the detection of phenotypic selection on resistance to herbivores confirms their ecological importance in determining plant fitness. However, evolutionary inferences based solely on phenotypic selection analyses must be interpreted with caution. 相似文献
1000.