首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
A-Crystallin can function like a molecular chaperone. We have recently shown that residues 71-88 in A-crystallin represent the chaperone active site of the protein. A peptide containing the sequence of A-crystallin sequence DFVIFLDVKHFSPEDLTVK (mini A-crystallin) by itself displays the antiaggregation property of A-crystallin. We have prepared a complex of reduced -lactalbumin and mini-A-crystallin and investigated the nature, conformation, and properties of the complex by dynamic light scattering, HPLC analysis, CD spectroscopy, and fluorescence studies. Although mini-A was able to prevent the precipitation of reduced -lactalbumin, large aggregates (50-500 nm) of the complex were formed during the assay. Amino acid composition estimation revealed that -lactalbumin and mini-A-crystallin were present in 1:2 ratio in the aggregates. During our study significant red shift in the Trp fluorescence emission maximum and an increase in Bis-ANS binding to the mini A-crystallin-bound -lacatalbumin were observed. The CD spectra of the complex showed a significant loss of -helical content but the -sheet content appeared to be less affected, indicating the molten-globule state of the reduced lactalbumin in the complex. These data show that the active site of A-crystallin by itself can maintain a significantly denatured and unfolded protein in soluble form.  相似文献   

2.
Synopsis Commercial samples of Erythrosin B (CI 45430), Erythrosin Y (CI 45425), Fluorescein (CI 45350), Phloxine (CI 45410) and Rose Bengal (CI 45440) have been analysed by thin-layer chromatography. The Erythrosins were found to be mixtures consisting in the main of 4-iodofluorescein, 4,5-di-iodofluorescein, 2,4,5-triiodofluorescein and 2,4,5,7-tetraiodofluorescein, in some instances together with 2,4,5-tri-iodo-4,5,6,7-tetrachlorofluorescein and 2,4,5,7-tetraiodo-4,5,6,7-tetrachlorofluorescein. Samples of Fluorescein were mixtures of the nominal dye usually with traces of several unidentified, fluorescent components. Those of Phloxine consisted mainly of mixtures of 4-bromo-4,5,6,7-tetrachlorofluorescein, 4,5-dibromo-4,5,6,7-tetrachlorofluorescein, 2,4,5-tribromo-4,5,6,7-tetrachlorofluorescein and 2,4,5,7-tetrabromo-4,5,6,7-tetrachlorofluorescein, often with 4,5,6,7-tetrachlorofluorescein Samples of Rose Bengal were mixtures of 4-iodo-4,5,6,7-tetrachlorofluorescein, 4,5-di-iodo-4,5,6,7-tetrachlorofluorescein, 2,4,5-tri-iodo-4,5,6,7-tetrachlorofluorescein and 2,4,5,7-tetraiodo-4,5,6,7-tetrachlorofluorescein together with some unidentified components.Most of the commercial dye samples gave an insoluble residue when extracted with methanol. This residue was usually inorganic carbonate or halide. Some possible practical consequences of the various impurities are discussed.  相似文献   

3.
A simple method for stimulating and maintaining high in vitro multiplication of Narcissus shoot clump cultures was developed. Shoot clumps were subjected either to normal cutting where leaves were trimmed to 20 mm in length at the beginning of each culture passage or to severe cutting where shoot clumps were cut down to the basal plate region removing all green tissue. Severe cutting at the beginning of each culture passage initially doubled the leaf multiplication, compared to normal cutting, but the difference between cutting treatments declined in successive passages. The improvement in leaf multiplication was maintained when shoot clumps were subjected to severe cutting only at every other culture passage, with no cutting in the alternate recovery passages. In vitro multiplication was increased by severe cutting in all seven Narcissus cultivars which were tested.Abbreviations NAA-1 naphthylacetic acid - BAP benzylaminopurine  相似文献   

4.
Composition of cellular fatty acids was determined for strains of fastidious, Gramnegative, xylem-limited bacteria causing or associated with Pierce's disease of grapevine, phony disease of peach, plum leaf scorch, stunt of ragweed, elm leaf scorch, and periwinkle wilt. The most abundant fatty acids were straight-chain 150, 160, 170, and 180, unsaturated 161, 181, and unsaturated 17-and 19=carbon homologs. Minor fatty acids included straightchain 120, 140, 190, and 200; an unsaturated 15-carbon homolog; hydroxy-substituted 2-OH 120, 3-OH 120, and 3-OH 140; and branched chain iso-140 and iso-200. Cyclopropane acids were not detected. Physiological age had no effect on fatty acid composition. Class analysis of data indicated relative uniformity within the group. Saturated even-carbon chains comprised 31%–42%, unsaturated acids 41%–52%, saturated odd-carbon chains 10%–18%, hydroxysubstituted chains 2%–7%, and branched-chains 1%–4% of total fatty acids. The ratio of saturated-unsaturated acids ranged from 0.8 to 1.2.  相似文献   

5.
Summary Two winter wheat genotypes (Diószegi 200 and Mv 15) were compared for their in vitro androgenic capacity. On average, the induction frequency of embryogenic structures was 71.7% in Diószegi 200 and only 4.3% in Mv 15. The haploid induction ability of the two genotypes differed considerably, with Diószegi 200 being much higher. The difference in the in vitro inductability of the microspores may result from genetic differences which are manifested in the survival rate of the microspores during the culture period and their adaptability to in vitro conditions. Special DNA fluorochrornes were suitable for studying the different pathways of in vitro androgenesis. Our data indicate that the repeated equal divisions of the microspore nucleus might lead to pollen embryo formation, and subsequent divisions of the vegetative portion of the pollen grain after the first asymmetric microspore mitosis can result in pollen callus formation.  相似文献   

6.
Three sialosylated and three neutral glycosphingolipids sharing a common iso-neolacto core were isolated from porcine kidney cortex. They were purified by preparative HPTLC, and were characterized by partial exoglycosidase hydrolysis followed by thin layer chromatography and immunostaining with anti-Gal13Gal, anti-type 2 lactosamine and anti-Lewisx antibodies, methylation analysis, MALDI-TOF mass spectrometry and 1H-NMR spectroscopy. Among neutral glycolipids, one was a known structure, VI3VI3(Gal)2-iso-nLc8Cer, and two were novel structures differing by the number of Gal3Lewisx determinants: VI3VI3(Gal)2V3Fuc-iso-nLc8, and VI3VI3(Gal)2 V3V3(Fuc)2-iso-nLc8. The single Gal3Lewis x determinant was found on the 6-linked antenna. Among sialosylated glycolipids, two had been previously found in other species and tissues, VI3VI3(NeuAc)2-iso-nLc8, and VI3NeuAcVI3Gal-iso-nLc8. A novel structure was discovered presenting a Gal3Lewisx determinant on the 6-linked antenna and a N-acetylneuraminic acid on the 3-linked antenna, VI3NeuAcVI3GalV3Fuc-iso-nLc8. These results indicate that, in vivo, the porcine kidney 3fucosyltransferase synthesizes the Gal3Lewisx determinant, acting on the 6-linked before the 3-linked Gal3neolactosamine, and appears unable to synthesize the sialosylated Lewisx determinant on neolactoseries glycolipids.  相似文献   

7.
As culture-bound syndromes, Japanese shinkeishitsu (constitutional neurasthenia) and taijinkyfush (anthropophobia) have received considerable attention in the Japanese literature. While these disorders are viewed as diagnostically distinct from Western psychiatric categories, recent studies by the Japanese suggest some affinity with Western social phobias, depression, and schizophrenia. The paper reviews this literature and offers suggestions for further cross-cultural research.This paper was accepted for publication prior to the compilation of Volume 13, No. 2, Neurasthenia in Asian Cultures. Consequently it does not refer to the papers in that volume, several of which are very relevant to the discussion in this paper.  相似文献   

8.
Summary The subunit composition of glutenin was analysed by SDS-polyacrylamide-gel electrophoresis using two varieties of contrasting pedigrees. Maris Widgeon, a variety of good bread-making quality, was shown to contain 2 glutenin subunits not present in Maris Ranger, a much higher yielding variety that is unsuitable for making bread. A third subunit was only found in Maris Ranger glutenin. To determine if any of these subunits are directly related to bread-making quality, 60 randomly-derived F2 progeny from a Maris Widgeon x Maris Ranger cross were analysed for bread-making quality and for glutenin subunit composition. A strong correlation was demonstrated between the presence of one of the two subunits inherited from Maris Widgeon, and quality. This subunit (termed subunit 1 glutenin) had an approx. mol. wt. of 145,000. It was also found in Maris Freeman, a bread-making variety selected from the same cross previously made in 1962. In further crosses involving Maris Widgeon or its descendants, more bread-making varieties have been produced in the last decade at the Plant Breeding Institute, Cambridge and all but one have inherited glutenin subunit 1. The subunit has been traced back through Holdfast to White Fife, a Canadian hard spring wheat of excellent breadmaking quality. Some 67 varieties were screened for the presence of glutenin subunit 1 and it was found in 31% of them. Several unrelated varieties of good bread-making quality did not contain subunit 1 glutenin.  相似文献   

9.
Summary Crude protein extracts from single seeds of nondomesticated Mexican bean accessions were analysed by SDS polyacrylamide gel electrophoresis for variability in phaseolin protein. Six new phaseolin types; M1, M2, M3, M4, M5, M6, which contained polypeptides within the same range of molecular weights (51,000 to 45,000 daltons) as occur in the S, T and C phaseolin types of cultivated beans were identified. No T and C types were found among the non-domesticated Mexican accessions, and the S type occurred in less than 7% of the seeds screened. Genetic analyses of F2 progenies from crosses between Sanilac (S), and five of the M types showed that each M phaseolin phenotype was allelic to the S type and expressed codominantly.  相似文献   

10.
The tetrasaccharides GalNAcß1-4[NeuAc2-3]Galß1-4Glc and GalNAcß1-4[NeuAc2-3]Galß1-4GlcNAc were synthesised by enzymic transfer of GalNAc from UDP-GalNAc to 3-sialyllactose (NeuAc2-3Galß1-4Glc) and 3-sialyl-N-acetyllactosamine (NeuAc2-3Galß1-4GlcNAc). The structures of the products were established by methylation and1H-500 MHz NMR spectroscopy. In Sda serological tests the product formed with 3-sialyl-N-acetyllactosamine was highly active whereas that formed with 3-sialyllactose had only weak activity.  相似文献   

11.
Summary Genetic analysis of heading date and spikelet number was carried out in the common wheat (Triticum aestivum L.) multispikelet line Noa, by using the monosomic series of the regular line Mara. Noa's high number of spikelets was found to be controlled by a recessive major gene on chromosome 2D; a slight reduction in spikelet number was induced by another recessive gene on Noa's 7A chromosome. Noa's late heading date was found to be controlled by two recessive genes, located on chromosome 2D (a major effect) and 6B (a minor effect). The nature of the genes located on Noa's 2D chromosome and the relationship between spikelet number and heading date are discussed.  相似文献   

12.
The -anomer of glucose relative to the -anomer was more rapidly metabolized into lactate by rat erythrocytes at 37° C (/ ratio = ca. 1.3): the amounts of - and -D-glucose metabolized into lactate during 3 min were 0.21 and 0.27 mol/gHb, respectively. Also, the transport of -D-glucose into erythrocytes was more rapid than that of -D-glucose: the amounts of - and -D-glucose transported into erythrocytes during 3 min were approximately 3.5 and 5.0 mol/gHb, respectively. Glucose phosphorylation by rat erythrocyte hexokinase (i.e., a possible rate-limiting step in glycolysis) occurred at higher velocities with the -anomer than with the a-anomer (/ ratio = 1.28). The Km value of hexokinase for either anomer of glucose was 53 M. The glucose concentrations in erythrocytes incubated with - and -D-glucose reached about 1 mM in 1 min, indicating that hexokinase is almost completely saturated with glucose within less than 1 min. The results suggest that glucose phosphorylation and glucose transport are major and minor determinants, respectively, for the anomeric preference of glucose utilization in rat erythrocytes.  相似文献   

13.
Resumen El procedimiento de intercambio iónico empleado en este trabajo ha mostrado ser un método eficiente, sencillo y rápido, para eliminar las fracciones antigénicas aniónicas de un extracto crudo deP. brasiliensis.Su empleo permitió la obtención de un antígeno purificado que contiene algunas de las fracciones catiónicas del extracto crudo. El antígeno responsable de la formación del arco E fue identificado en el extracto purificado, mediante análisis inmunoelectroforético.  相似文献   

14.
A. F. G. Dixon 《Oecologia》1972,9(4):301-310
Summary The ability of the lime aphid to produce sexuals (males and females) as an alternative to parthenogenetic females is regulated by a timing mechanism (interval timer) which restrains the appearance of these morphs early in the year. In this species there are two interval timers: one controls the production of sexual females, and the other controls the production of males. Both intervals timers are sensitive to day-length and temperature but they respond in different ways.With the approach of autumn the waning effect of the interval timer inhibiting female production combined with the short day-lengths results in an increasing proportion of the aphids developing into sexual females. The restraining effect of the interval timer results in a gradual transition from parthenogenetic to gamic reproduction over a period of several generations and is still operational in the autumn. However, in this species even relatively long day conditions (17 h) can induce the development of oviparae. This low threshold of response to day-length combined with the short generation time results in the sexual morphs appearing very early in the year. This is of considerable adaptive significance in years when, as frequently happens, the aphids disappear locally before the onset of autumn.  相似文献   

15.
Evidence for the genomic organization of human lambda light chain joining (J) region gene segments is presented. A mouse J probe was used in Southern hybridizations to localize joining region sequences in a cosmid clone containing the genomic cluster of six human lambda constant (C) region gene segments. The results of these hybridizations suggest the presence of at least one J gene segment upstream from each constant region gene segment. The DNA sequences indicate that the human JI, J2, and J3 gene segments have consensus nonamer and heptamer sequences, proposed to be involved in V-J joining, are capable of encoding the known amino acid sequences for the respective J peptides, and have a sequence which could give functional RNA splice site at the end of their coding regions. Our data show that a single functional J is located 1.3 or 1.6 kb upstream of each of the C gene segments known to encode the Mcg, Kern Oz, and KernOz+ isotypes. Therefore, the gene organization of this region of the human lambda locus is J1 CI -J2C2-J3C3. The DNA sequences ofJ 1,J 2, andJ 3 presented in this paper establish that a singleJ gene segment precedes each expressed C gene segment, and support a model for the evolution of the human JC clusters where JICI andJ2C2-J3C3. arose from different ancestral JC units.  相似文献   

16.
Summary Alpha-globin genes were analyzed by the direct method of DNA mapping using - and -globin specific probes in a Thai family in which the proposita was an unusually mild °-thalessemia homozygote. °-Thalessemia was found to be segregating in the family, inherited from the proposita's father by one of her younger sisters. However, °-thatlessemia was not detected by this DNA mapping in the proposita. The mild homozygous °-thalessemia in this family may result from interactions of a non-deletion -thalassemia, a gene responsible for high proteolytic activity permitting more balanced globin-chain levels, or from an unusually active hemoglobin F production in the proposita.  相似文献   

17.
RFLP analysis was conducted on a population derived from a three-way cross to determine the location of the hybrid sterility locus, S-5, in relation to mapped molecular markers and to identify markers that would be useful for selection in breeding. S-5 is of interest to rice breeders because it is associated with spikelet sterility of F1 hybrids in Indica/Japonica crosses. Identification of an S-5 allele which confers fertility in Indica/Japonica hybrids when introgressed into either the Indica or the Japonica parent has been reported. Varieties carrying this S-5 n allele are known as wide compatibility varieties (WCV). Our data suggests that RFLP marker RG213 on chromosome 6 is closely linked to the S-5 locus and can be efficiently used to identify wide compatibility (WC) lines. RG213 is a single-copy genomic clone that detects three bands of different molecular weights in DNA from Japonica (Akihikari) and Indica (IR36) varieties and WC line (Nekken 2). We demonstrate that the three alleles detected by this marker could be used to trace the inheritance of the wide compatible phenotype in breeders' material.  相似文献   

18.
Summary An experimental manipulation of clutch size was carried out on a wild population of the cooperatively breeding Bell Miner (Manorina melanophrys, Meliphagidae) to assess which factor(s) limit clutch size in this species. Results provide some support for the trade-off hypothesis since there is a cost of reproduction for the breeding female in terms of loss of body mass. The breeding female performs most of the nestling care. Clutches of three eggs are also laid during the mid-breeding season which is the period most favourable for breeding (i.e. nestlings grow faster). This evidence also supports the intrabrood competition hypothesis. Clutches that have lost an egg were more likely to be deserted; this may be an antipredator strategy since partial clutch predation has been recorded in the field. Nest predation was high in this study (64.9%), suggesting that many small clutches may be a strategy to decrease the effect of nest predation on reproductive success over the whole breeding season (nest predation hypothesis). Both the trade-off hypothesis and the nest predation hypothesis may apply in this case since they are not mutually exclusive. The size of the attending group did not greatly affect reproductive success in the short term, although if both age structure and size of the group are taken into account, reproductive success can be better predicted.  相似文献   

19.
Summary Human liver alcohol dehydrogenase (ADH) variants were screened in random autopsy specimens from 53 North German and 34 Japanese individuals. Based on pH-activity profile and electrophoretic pattern, only ADH2 and ADH3 variants were detected. In relatively fresh specimens, an anodic band or -ADH band was also observed. The recently reported new molecular forms collectively called ADHIndianapolis (Bosron et al. 1980) could not be demonstrated and therefore may be confined hitherto only to the American black population.This paper is dedicated to Professor Dr. Dr. H. Baitsch on his 60th birthday  相似文献   

20.
The influence of interferon alpha and gamma alone or in combination on the augmentation of human natural cytotoxicity was studied. Treatment of peripheral blood lymphocytes with IFN- led to a rapid augmentation of NK activity, in contrast to IFN- where target cell killing was observed only following 18 hrs exposure of lymphocytes to IFN-. The results of the single cell assay paralleled those obtained using the Chromium release test, but neither interferon type caused an increase in the number of target binding lymphocytes. The combined effect of IFN- and IFN- in stimulating human natural cytotoxicity demonstrated individual lymphocyte responses to be variable. Exposure of lymphocytes to IFN- and IFN- for 18 hrs prior to assay for cytotoxicity usually decreased the level of cytotoxicity compared with control values, whereas other treatment regimes gave an additive and sometimes synergistic effect. Only treatment with IFN- for 18 hrs and IFN- for one hr produced a synergistic response in the majority of individuals tested. We conclude from this study that individual responses to IFN- and IFN- alone or in combination are variable and dependent upon timing of exposure of lymphocytes to individual interferon types, and possibly reflects the donor status at the time of sampling.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号