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91.
The neurointermediary lobes from 190 rat pituitaries were homogenized in an acidic medium which inhibits peptidase activity and maximizes the solubilization of undamaged peptides. Octadecylsilyl-silica (ODS-silica) was used to extract the supernatant of the tissue homogenate. The ODS-silica eluate, now largely protein and salt free, was subjected to reversed-phase high-performance liquid chromatography (HPLC) employing 0.1% trifluoroacetic as counter ion. The column eluates were monitored for beta-endorphin immunoreactivity. Five immunoreactive components were observed. The most hydrophobic of these was repurified on the same HPLC column using 0.13% heptafluorobutyric acid as counter ion. Characterization of the purified peptide by gel permeation HPLC, amino acid analysis, and tryptic fragmentation indicated that it corresponded in structure to alpha-N-acetyl-beta-endorphin1-26. Amino acid analysis of the native peptide and its trypsin and carboxypeptidase fragments indicated that an alanyl residue occupies position 26. This finding is in contrast to the sequence predicted for the beta-lipotropin/corticotropin precursor by recombinant DNA techniques which suggests that the 26th residue of the beta-endorphin molecule should be valine. 相似文献
92.
de Vries J. N. 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1983,66(3-4):329-339
Summary The recombination fraction between the interstitially located gene an and interchange 303 of rye was found to be 0.244±0.038 in a test cross using the translocation as the male parent. In first metaphase translocation configurations in pollen mother cells of the same plant, the chiasma frequency between an and the translocation breakpoint was found to be significantly more than twice the recombination fraction. Recombination was concluded to be masked by a difference in the alternate frequency between configurations without interstitial chiasmata and configurations with interstitial chiasmata, the effect of the first type being of major importance. Random centromere orientation of translocation multivalents with interstitial chiasmata was concluded to be a realistic assumption. The exceptionally high recombination between an and translocation 303 is discussed. Consideration is also given to the use of interchanges in the establishment of a marker's chromosomal position, and to the use of translocation chromosomes in balanced systems for hybrid breeding purposes. 相似文献
93.
Behavior of lactating rats in a dual-chambered maternity cage 总被引:2,自引:0,他引:2
Videotape sampling of behavior in a dual-chambered apparatus indicates that the continuous monitoring of the amount of time a mother spends in the cage with its litter can be taken as a valid reflection of maternal behavior. Nursing is the principal behavior of lactating females while in the compartment with their litters; lying still, consummatory behavior, and activity occur with greater frequency in the cage away from the litter. Both the time that mothers spend with their litters and nursing behavior displayed a 24-hr rhythm with crest values occurring during the period of light. 相似文献
94.
95.
再生植株具有高频率的染色体异常,其中有20.61%表现为染色体数量变异,最常见的为2n—1类型,其次为2n—2类型,也有2n 1、2n—3个体以及染色体数嵌合株。再生植株减数分裂各期均有染色体异常行为,可以见到的有落后染色体、染色体桥、断片、二分体延迟、微核,还有粗线期十字型配对等结构变异,以及五分体、六分体和畸型四分体等异常现象。微核率随培养时间延长而增加,可用作染色体伤害的一个指标。再生植株R_1代存在着许多形态学变异。性状变异与染色体数目变异没有明显关系。 相似文献
96.
Andrea Streit reas Faissner Bernd Gehrig Melitta Schachner 《Journal of neurochemistry》1990,55(5):1494-1506
The monoclonal L5 antibody reacts with an N-glycosidically linked carbohydrate structure which is present on the neural cell adhesion molecule L1, neural chondroitin sulfate proteoglycans, and other not yet identified glycosylated proteins. Using this antibody, we isolated and characterized proteoglycans from adult mouse brain and cultured astrocytes biosynthetically labeled with Na2 35SO4 and a 3H-amino acid mixture. Our data suggest that the L5 proteoglycans of both sources are identical in their biochemical properties. The apparent molecular mass of the L5 proteoglycan is approximately 500 kDa. Digestion of the iodinated L5 proteoglycan from mouse brain and of the [35S]methionine-labeled L5 proteoglycan from cultured astrocytes with proteinase-free chondroitinases ABC and AC revealed three major core proteins with apparent molecular masses of approximately 380, 360, and 260 kDa. These represent molecularly distinct protein cores. 相似文献
97.
向日葵离体孤雌生殖的超微结构研究 总被引:5,自引:1,他引:4
本文是研究未受精胚珠培养诱导的孤雌生殖过程超微结构变化的首次报道。向日葵(Heliaanthus annuus L.)的卵细胞在离体条件下被激活,发生细胞核移位、极性丧失、细胞器增多并转变成活动状态、液泡化程度增大、合点端形成细胞壁等一系列变化,预示即将启动孤雌生殖。孤雌生殖的原胚具有若干显著特征,如极性颠倒、有自体吞噬活动、壁的自由生长、游离核分裂等。对这些现象作了初步的讨论。 相似文献
98.
Robert L. Uffen Annette Colbeau Pierre Richaud Paulette M. Vignais 《Molecular & general genetics : MGG》1990,221(1):49-58
Summary
Rhodocyclus gelatinosus grew photosynthetically in the light and consumed H2 at a rate of about 665 nmol/min per mg protein. The uptake-hydrogenase (H2ase) was found to be membrane bound and insensitive to inhibition by CO. The structural genes of R. gelatinosus uptake-H2ase were isolated from a 40 kb cosmid gene library of R. gelatinosus DNA by hybridization with the structural genes of uptake-H2ase of Bradyrhizobium japonicum and Rhodobacter capsulatus. The R. gelatinosus genes were localized on two overlapping DNA restriction fragments subcloned into pUC18. Two open reading frames (ORF1 and ORF2) were observed. ORF1 contained 1080 nucleotides and encoded a 39.4 kDa protein. ORF2 had 1854 nucleotides and encoded a 68.5 kDa protein. Amino acid sequence analysis suggested that ORF1 and ORF2 corresponded to the small (HupS) and large (HupL) subunits, respectively, of R. gelatinosus uptake-H2ase. ORF1 was approximately 80% homologous with the small, and ORF2 was maximally 68% homologous with the large subunit of typical membrane-bound uptake-H2ases. 相似文献
99.
Apparent phytotoxicity of mononuclear hydroxy-aluminum to four dicotyledonous species 总被引:3,自引:0,他引:3
It has long been assumed that Al3+ is an important rhizotoxic ion in acid soils around the world, but the toxicity of Al3+ relative to mononuclear hydroxy-Al [AlOH2+ and Al(OH)+ 2 ] has been examined in detail only for an Al-sensitive wheat variety ( Triticum aestivum L. cv. Tyler). That plant appears to be sensitive to Al3+ but not to AlOH2+ and Al(OH)+ 2 . New experiments, and reanalyses of previously published experiments, provide evidence that dicotyledonous species may be sensitive to mononuclear hydroxy-Al and that Al3+ may be nontoxic, or less toxic, to those plants. Despite these consistently measured differences between wheat and the dicotyledons, the determination of relative toxicities (Al3+ vs mononuclear hydroxy-Al) may be an intractable problem. Because of hydrolysis equilibria, (AlOH2+ ) and (Al(OH)+ 2 ) are equivalent to (Al3+ )k1 (H+ )−1 and (l3+ )k2 (H+ )−2 , respectively, in which k1 and k2 are the first and second hydrolysis constants (braces denote activities). Thus, any expression of root elongation as a function of mononuclear hydroxy-Al can be alternatively expressed as a function of (Al3+ ) and (H+ ). Toxicity attributed to mononuclear hydroxy-Al may actually be Al3+ toxicity that increases as pH rises (i.e. Al3+ toxicity ameliorated by H+ ). 相似文献
100.
Ian C. Murfet 《Physiologia plantarum》1990,79(3):497-505
Dwarf pea (Pisum sativum L.) plants with genotypes cryc and crys responded differently when an 8 h photoperiod (8 h daylight, 16 h dark) was extended to 24 h (8 h daylight, 16 h incandescent light). Genotype cryc showed up to a 4-fold increase in internode length, sustained by increases in both cell length (particularly of epidermal cells) and cell number (particularly of cortical cells) while crys plants showed up to a 2-fold increase in internode length sustained mostly by an increase in cell number. Under an 8 h (daylight) photoperiod the two genotypes did not differ in their sensitivity to applied gibberellin A1 (GA1) and they showed a similar pattern of response. GA1 significantly increased internode length, cell length and cell number in both genotypes. Incandescent light did not increase the size of the response to GA1 except for crys plants at high dose rates of GA1 (29–58 nmol). At saturating doses of GA1 the two genotypes attained a similar peak internode length; incandescent light increased the peak by about 40%. GA1 increased the rate of leaf appearance by up to 33% while incandescent light reduced the rate by 4–7%. The elongation response of the more mature internodes of cryc plants to GA1 or incandescent light was due primarily to an increase in cell length whereas increased cell number made a significant contribution in the case of internodes which were relatively immature at the time the stimulus was applied. The progressive increase in internode length of both genotypes during ontogeny was due primarily to an increase in cell number. In conclusion, alleles cryc and crys (background le La) do not confer a difference in sensitivity to GA1 and the increase in internode length in response to incandescent light is probably not the result of a real or perceived increase in GA1 level. Allele crys may partially block a phytochrome mediated response to light and the key difference between genotypes crys and cryc may lie in the greater elongation (extensibility?) of cryc epidermal cells in incandescent light. 相似文献