沙田柚自交、异交花粉管蛋白双向电泳分析

比较分析了沙田柚自交、异交花粉管蛋白的双向电泳图谱 ,两者的蛋白分布格局相似 ,具有重叠性 ,可分辨出 2 0 0多个蛋白点。在异交花粉管电泳图谱中发现了 1种特异蛋白 (A) ,A蛋白 (MrA =5 8.2 ,pI=5 9) ;在自交花粉管电泳图谱中发现了 2种特异蛋白 (B、C) ,B蛋白 (MrB =2 6.4,pI=6.1 ) ,C蛋白 (MrC =2 8 0 ,pI=6.3) ,这些蛋白可能与自交不亲和有关     

The quantal theory of how the immune system discriminates between "self and non-self"

In the past 50 years, immunologists have accumulated an amazing amount of information as to how the immune system functions. However, one of the most fundamental aspects of immunity, how the immune system discriminates between self vs. non-self, still remains an enigma. Any attempt to explain this most intriguing and fundamental characteristic must account for this decision at the level of the whole immune system, but as well, at the level of the individual cells making up the immune system. Moreover, it must provide for a molecular explanation as to how and why the cells behave as they do. The "Quantal Theory", proposed herein, is based upon the "Clonal Selection Theory", first proposed by Sir McFarland Burnet in 1955, in which he explained the remarkable specificity as well as diversity of recognition of everything foreign in the environment. The "Quantal Theory" is built upon Burnet's premise that after antigen selection of cell clones, a proliferative expansion of the selected cells ensues. Furthermore, it is derived from experiments which indicate that the proliferation of antigen-selected cell clones is determined by a quantal, "all-or-none", decision promulgated by a critical number of cellular receptors triggered by the T Cell Growth Factor (TCGF), interleukin 2 (IL2). An extraordinary number of experiments reported especially in the past 20 years, and detailed herein, indicate that the T cell Antigen Receptor (TCR) behaves similarly, and also that there are several critical numbers of triggered TCRs that determine different fates of the T cells. Moreover, the fates of the cells appear ultimately to be determined by the TCR triggering of the IL2 and IL2 receptor (IL2R) genes, which are also expressed in a very quantal fashion. The "Quantal Theory" states that the fundamental decisions of the T cell immune system are dependent upon the cells receiving a critical number of triggered TCRs and IL2Rs and that the cells respond in an all-or-none fashion. The "Quantal Theory" accounts fully for the development of T cells in the thymus, and such fundamental cellular fates as both "positive" and "negative" selection, as well as the decision to differentiate into a "Regulatory T cell" (T-Reg). In the periphery, the "Quantal Theory" accounts for the decision to proliferate or not in response to the presence of an antigen, either non-self or self, or to differentiate into a T-Reg. Since the immune system discriminates between self and non-self antigens by the accumulated number of triggered TCRs and IL2Rs, therapeutic manipulation of the determinants of these quantal decisions should permit new approaches to either enhance or dampen antigen-specific immune responses.     

Implications of self/non-self discrimination for spatial patterning of clonal plants

Many clonal plants are characterised by tussock growth forms, but the mechanisms that account for their formation and maintenance are still vague. Here we examine the possible effects of the recently identified phenomenon of self/non-self discrimination on the spatial distribution and patterning of ramets, tussocks and clones in stands of clonal plants. Spatially explicit ramet-based simulation modeling of growth and competition have shown that compact tussocks can be generated as a transient phenomenon that typically disappears at equilibrium. We introduced self/non-self discrimination into a spatial model by decreasing competition between neighbouring ramets on the same clonal fragment. The results demonstrate that self/non-self discrimination can have significant effects on clonal growth and architecture with a clear tendency to generate long-lasting and self-sustaining clumps. Interestingly, this effect was qualitatively independent of other architectural and growth attributes of the plants, making it a candidate mechanism of stable clumped growth forms observed in many clonal plants and communities. Furthermore, the introduction of self/non-self discrimination shifted competition from the level of ramets to that of clonal fragments, which in turns strongly increased genet extinction rates. Our results stress the need for greater attention to the rather neglected scaling up of physiological and morphogenetical controls to the population and community levels.     

Innate sensing of self and non-self RNAs by Toll-like receptors

Toll-like receptors (TLRs) have an important role in innate immunity in mammals by recognizing conserved microbial components that are known as pathogen-associated molecular patterns (PAMPs). Although the majority of these receptors sense pathogen components on the cell surface, a subset of them (TLR3, TLR7, TLR8 and TLR9) senses viral and bacterial nucleic acids in endosomal compartments. Of considerable interest is the recent finding that TLR7 and TLR8 can also recognize small interfering RNA (siRNA), which is the main effector in RNA interference. This immune activation by siRNAs can be abrogated by the 2'-ribose modification of uridines. Here, we discuss the recent developments that have expanded the understanding of self-non-self discrimination of RNAs by the innate immune system, and consider future directions for therapeutic applications of these findings.     

A quantitative measure for discriminating between self and non-self antigens in immune response

We present a new theory of how lymphocyte–antigen interaction is governed. We present ‘chronicity’, a quantitative record of previous lymphocyte–antigen interactions, which is used to regulate lymphocyte behavior. When the chronicity of a lymphocyte increases with the interaction and gets beyond the lower threshold, the lymphocyte can proliferate. Non-self antigens cause lymphocyte proliferation which destroys the antigen. However, self antigens are not destroyed. When the chronicity gets beyond the upper threshold, the lymphocytes get in the tolerance state ensuring non-destruction of self antigens. The discrimination between self and non-self results from the difference in the termination process between self and non-self antigens, caused by the difference in the frequency between interaction of lymphocyte with both antigens.     

Clonal interactions in fibroblast proliferation: recognition of self vs. non-self

The proliferation and aging of fibroblast populations has been postulated to include a process of clonal selection. Using carbocyanine dyes to label clonal fibroblast populations, we were able to follow their growth in mixed cultures. Individual fibroblast clones seeded as the minority population (20%) with either another clone or the parent line (differentially labeled) always demonstrated increase relative growth so that, by the end of 4 weeks, approximately equal numbers of both populations were present. Labeled cells of the same clone mixed as the minority population with differentially labeled cells of the same clone maintained their minority status. The results indicate that clonal populations of fibroblasts are able to recognize "self" as different from "non-self" and that this recognition leads to alterations in cellular proliferation.     

Critical analysis of the immunological self/non-self model and of its implicit metaphysical foundations

An examination of the concepts used in immunology prompts us to wonder about the origins and the legitimacy of the notions of self and non-self, which constitute the core of the dominant theoretical model in this science. All theoretical reflection concerning immunology must aim at determining a criterion of immunogenicity, that is, an operational definition of the conditions in which an immune reaction occurs or does not occur. By criticizing both conceptually and experimentally the self/non-self vocabulary, we can demonstrate the inaccuracy and even the inadequacy of the dichotomy of self/non-self. Accordingly, the self/non-self model must be reexamined, or even rejected. On the basis of this critique, we can suggest an alternative theoretical hypothesis for immunology, based on the notion of continuity. The 'continuity hypothesis' developed here attempts to give a criterion of immunogenicity that avoids the reproaches leveled at the self model.     

Effect of physiological integration in self/non-self genotype recognition on the clonal invader Carpobrotus edulis

Aims Biological invasions represent one of the most important threats to the conservation of biodiversity; however, the mechanisms underlying successful invaders remain unsolved. Many of the most aggressive invaders show clonal growth, and capacity for clonal integration has been pointed out recently as an important trait explaining the success of invasive plants. We aim to determine the role of physiological integration in the capacity for self/non-self genotype recognition in the clonal invader Carpobrotus edulis and the implications of this capacity for the expansion of this aggressive invader.Methods We used connected and severed ramets of identical or different genotype and we determined the capacity for self/non-self recognition by comparing changes in biomass partitioning to avoid competition for resources between pairs of ramets.Important findings Physiological integration allowed self/non-self genotype recognition in the invader C. edulis. Results showed a significant effect of physiological integration on the biomass allocated to roots by genetically identical ramets: older ramets specialize in acquisition of soil-based resources and younger ramets specialize in lateral expansion. This specialization could be considered a form of division of labour, which reduce intra-genotype competition. This is the first evidence that division of labour could be interpreted as a form of self/non-self recognition between genetically identical ramets. Capacity for self/non-self discrimination could contribute to increase the colonization capacity of the aggressive invader C. edulis. This is the first study showing an association between self/non-self recognition and invasiveness in a clonal plant.     

An approach for high-throughput structure determination of proteins by NMR spectroscopy

An approach is described for rapidly determining protein structures by NMR that utilizes proteins containing ¹³C-methyl labeled Val, Leu, and Ile (1) and protonated Phe and Tyr in a deuterated background. Using this strategy, the key NOEs that define the hydrophobic core and overall fold of the protein are easily obtained. NMR data are acquired using cryogenic probe technology which markedly reduces the spectrometer time needed for data acquisition. The approach is demonstrated by determining the overall fold of the antiapoptotic protein, Bcl-xL, from data collected in only 4 days. Refinement of the Bcl-xL structure to a backbone rmsd of 0.95 Å was accomplished with data collected in an additional 3 days. A distance analysis of 180 different proteins and structure calculations using simulated data suggests that our method will allow the global folds of a wide variety of proteins to be determined.     

An exercise on the determination of the primary structure of proteins

An exercise is described which illustrates how a simple laboratory investigation may be complemented with suitable related logical and numerical problems to increase its educational scope. The exercise extends the students' analysis of an unknown dipeptide to the larger problem of the primary structure of a polypeptide. As far as possible it reiterates techniques already used in the laboratory and involves photographs and facsimilies of actual data mounted on large display cards. Thus it is an integral part of the laboratory work, rather than being a mere appendix to it.     

An immunochemical aid to sequence determination of proteins.

A specific radioimmunoassay for peptides has been developed using ¹²⁵I-labeled peptides and a double-antibody precipitation. Cross-reacting peptides are measured by inhibition of the binding of the labeled cyanogen bromide peptide to its antibody. The assay, which allows detection of picomole quantities, was used to monitor the purification of two overlapping tryptic peptides from a complex mixture of peptides. These were shown to contain a portion of the sequence of the radio-labeled cyanogen bromide peptide and a portion of the sequence of a cyanogen bromide peptide which follows in the polypeptide chain. The need to analyze many fractions in a digest in order to locate a desired peptide is thus avoided. The general suitability of this method for the purification of specific peptides from digestion mixtures of other large proteins is discussed.     

An improved method for the gas chromatographic determination of methionine in proteins and crude plant materials

Procedures for the determination of methionine in crude plant materials by means of cyanogen bromide digestion and gas chromatographic analysis of the digest were modified to achieve complete reaction, enhanced precision, and shortened reaction times. Oxides of methionine and derivatives of S-methylcysteine did not add to the values obtained for free and peptide-bound methionine.