The protein phosphatase-1 regulator NIPP1 is also a splicing factor involved in a late step of spliceosome assembly

NIPP1 is a ubiquitous regulator of protein phosphatase-1 (PP1) and is targeted to the splicing factor storage sites (speckles) in the nucleus by its forkhead-associated domain. We show here that NIPP1 is also a component of the spliceosomes in HeLa cell-splicing extracts and that the interaction with the spliceosomes requires a functional forkhead-associated domain. The in vitro splicing of beta-globin pre-mRNA was not affected by exogenous wild type NIPP1 but was blocked by mutants that lacked residues 225-329. The inhibition by these dominant negative mutants resulted from a block in a late phase of spliceosome assembly, i.e. at the transition between the B-complex and the C-complex. Site-directed mutagenesis furthermore showed that this spliceosomal function of NIPP1 was unrelated to its ability to bind PP1 or RNA. Our data suggest that NIPP1 can function independently as a splicing factor and a phosphatase regulator.     

Diversity of Nosema associated with bumblebees (Bombus spp.) from China

Bumblebees (Bombus spp.) are important pollinators of many economically important crops and microsporidia are among the most important infections of these hosts. Using molecular markers, we screened a large sample (n=1,009 bees) of workers of 27 different Bombus spp. from China (Sichuan, Qinghai, Inner Mongolia, and Gansu provinces). The results showed that 62 individuals representing 12 Bombus spp. were infected by microsporidia with an overall prevalence of 6.1%. Based on the haplotypes (ssrRNA sequences), we confirmed the presence of Nosema bombi, Nosema ceranae and (likely) Nosema thomsoni. In addition, four new putatively novel taxa were identified by phylogenetic reconstruction: Nosema A, Nosema B-complex, Nosema C-complex and Nosema D-complex. In many cases, hosts were infected by more than one Nosema taxon. Possible caveats of sequence analyses are discussed.     

The major outer-membrane proteins of Chlamydia trachomatis serovars A and B: intra-serovar amino acid changes do not alter specificities of serovar- and C subspecies-reactive antibody-binding domains.

The major outer-membrane protein (MOMP) of Chlamydia trachomatis is a promising candidate antigen for chlamydial vaccine development. We have sequenced the MOMP genes for a serovar A and a serovar B isolate and have compared these new sequences with those already reported. Intra-serovar changes in the inferred amino acid sequences of the surface-exposed variable segments known to be responsible for binding of neutralizing antibody were observed. Nevertheless, epitope mapping with solid-phase peptides showed that these intra-serovar changes did not affect the binding of serovar- and subspecies-specific, potentially protective antibodies. Variable segment 1 of C. trachomatis serovar A contained two adjacent antibody-binding sites, one of which was C-subspecies specific while the other was serovar A specific. Therefore the subspecies binding site for C-complex organisms is in variable segment 1, whilst that for B-complex organisms is in variable segment 4. This work shows that MOMP sequences are relatively stable within the serovar categorization for isolates taken decades apart from different continents. Within a given serovar, however, limited interchange of functionally related amino acids may occur without impairing the binding of serovar-specific antibody.     

多糖对家禽免疫功能的影响

营养因素对家禽免疫具有重要作用。糖是家禽必须的重要营养元素之一,不仅是维持家禽正常生长、繁殖、生产不可缺少的组成成分与营养物质,也是调节家禽免疫器官、组织和免疫应答反应不可缺少的物质基础。本文就多糖对家禽的免疫器官发育、体液免疫、细胞免疫、非特异性免疫、细胞因子产生的影响等方面进行了综述。为指导家禽生产实践提供合理依据。     

Resistance of human leukocytes to vesicular stomatitis virus infection as one of the innate antiviral immune activities; participation of cell subpopulations

Among reactions of innate immunity, resistance of human peripheral blood leukocytes (PBL) to viral infection seems important. The purpose of our study was to find, which of the subpopulations of PBL is the most responsible for the innate antiviral immunity of these cells. The innate immunity was measured by using the direct method of infection of leukocytes with vesicular stomatitis virus (VSV). The lack of VSV replication by infected leukocytes (0-1 log TCID50) was taken as an indicator for complete immunity; a low level of VSV (2-3 log) for partial immunity; and high VSV titer (more than 4 log) for no immunity. The resistance/innate immunity of whole PBL and subpopulations such as: adherent cells, fractions enriched in lymphocytes T, and lymphocytes B (separated on column with nylon wool), NK(+) and NK(-) (separated by microbeads activated cell sorting MACS) differ from each other. All fractions express higher resistance/innate immunity than the whole PBL. NK(+) cells were found the most resistant fraction of PBL to VSV infection. The results indicate that among the leukocytes in PBL the regulation mechanisms of innate immunity exist. The study on the mechanism of innate immunity regulation as well as the role of NK in innate immunity of PBL must be continued.     

Genetic analysis of the functional relationship between colicin E3 and its immunity protein.

Partial deletions in the immunity gene of the colicin E3 operon were used to study possible functions of the immunity protein besides protection against exogenous colicin. Nuclease BAL-31 was used to create a series of carboxyl-terminal deletions of the immunity gene. Mutants displaying lowered immunity against exogenous colicin were found, and six that had reduced but detectable levels of immunity were chosen for further analysis. DNA sequence analysis of the deletions showed that all six terminated within the last five codons of the immunity gene. The wild-type immunity gene was replaced by each of the six mutated immunity genes in a plasmid containing an otherwise functional colicin E3 operon. Transformants containing the resulting plasmids produced smaller colonies on solid medium and grew more slowly in liquid culture than transformants carrying the wild-type colicin and immunity genes. This result suggested that immunity protein was required to protect the cell against endogenous colicin E3. This idea was confirmed in experiments in which the colicin E3 and immunity genes were independently cloned on two compatible plasmid vectors.     

Stochastic dynamics of immunity in small populations: a general framework

Assessment of immunological status is a powerful tool in the surveillance and control of infectious pathogens in livestock and human populations. The distribution of immunity levels in the population provides information on time and age dependent transmission. A stochastic model is developed for a livestock population which relates the dynamics of the distribution of immunity levels at the population level to those of pathogen transmission. A general model with K immunity level categories is first proposed, taking into account the increase of the immunity level due to an infection or a re-exposure, the decrease of the immunity level with time since infection or exposure, and the effect of immunity level on the susceptibility and the infectivity of individuals. Numerical results are presented in the particular cases with K=2 and K=3 immunity level categories. We demonstrate that for a given distribution of the immunity levels at the population level, the model can be used to identify quantities such as most likely periods of time since introduction of infection. We discuss this approach in relation to analysis of serological data.     

Immunocompetence of nestling great tits in relation to rearing environment and parentage

Theoretical models of host–parasite coevolution assume a partially genetic basis to the variability in susceptibility to parasites among hosts, for instance as a result of genetic variation in immune function. However, few empirical data exist for free-living vertebrate hosts to support this presumption. In a cross-fostering experiment with nestling great tits, by comparing nestlings of the same origin we investigated (i) the variance in host resistance against an ectoparasite due to a common genetic origin, (ii) the effect of ectoparasite infestation on cell-mediated immunity and (iii) the variance in cell-mediated immunity due to a common genetic origin. Ectoparasitic hen fleas can impair the growth of nestling great tits and nestling growth was therefore taken as a measure of host susceptibility. A common origin did not account for a significant part of the variation in host susceptibility to fleas. There was no significant overall effect of fleas on nestling growth or cell-mediated immunity, as assessed by a cutaneous hypersensitivity response. A common rearing environment explained a significant part of the variation in cell-mediated immunity among nestlings, mainly through its effect on nestling body mass. The variation in cell-mediated immunity was also related to a common origin. However, the origin-related variation in body mass did not account for the origin-related differences in cell-mediated immunity. The results of the present study thus suggest heritable variation in cell-mediated immunity among nestling great tits.     

无颌类脊椎动物适应性免疫系统的进化

适应性免疫系统的起源与进化问题一直是人们研究的热点, 以七鳃鳗为代表的无颌类脊椎动物, 被普遍认为处在进化出适应性免疫系统的边缘。因此, 研究无颌类脊椎动物适应性免疫的机制, 对揭示适应性免疫系统的起源与进化具有重要意义。研究表明, 无颌类在一定范围内具有高等脊椎动物特有的适应性免疫特征, 并发现了一些在结构或功能上与高等脊椎动物免疫相关基因同源的免疫因子。文章就近年来对无颌类脊椎动物适应性免疫系统机制的研究进展作一概述, 为进一步深入研究脊椎动物适应性免疫系统的起源与进化提供有益的参考。     

Molecular structure of the immunity gene and immunity protein of the bacteriocinogenic plasmid Clo DF13.

The nucleotide sequence of the Clo DF13 DNA region comprising the immunity gene has been determined. We also elucidated the aminoacid sequence of the 40 N-terminal and 7 C-terminal aminoacids of the purified immunity protein. From analysis of the data obtained we were able to locate the immunity gene between 11.7 and 14.5% on the Clo DF13 map, and to determine the complete aminoacid sequence of the immunity protein. It was observed that the Clo DF13 immunity gene encodes an 85 aminoacid protein and is transcribed in the same direction as the cloacin gene. These experimental data support our model, presented elsewhere, which implicates that the cloacin and immunity genes of Clo DF13 are coordinately transcribed from the cloacin promoter. We also present DNA sequence data indicating that an extra ribosome binding site precedes the immunity gene on the polycistronic mRNA. This ribosome binding site might explain the fact that in cloacinogenic cells more immunity protein than cloacin is synthesized. The comparison of the complete aminoacid sequence of the Clo DF13 immunity protein, with the aminoacid sequence data of the purified, comparable Col E3 immunity protein revealed that both proteins have extensive homologies in primary and secondary structure, although they are exchangeable only to a low extent in vivo and in vitro. It was also observed that a lysine residue was modified in immunity protein isolated from excreted bacteriocin complexes.     

Resistance of Calves to Reinfection with Eimeria bovis

SYNOPSIS. An immunity to reinfection with E. bovis was demonstrated in 3 experiments involving 60 calves. This immunity develops rapidly, as indicated by resistance to a challenge given 14 days after the immunizing inoculation. In 3 groups of 3 to 6 young calves each, immunity was still present to a moderate degree 2 to 3 months after inoculation; in one group of 5 animals about a year old there was apparently a high degree of immunity about 7 months after the last inoculation. In one experiment an immunizing inoculum of 10,000 oöcysts did not produce as much immunity as 50,000 oöcysts. In 2 experiments there appeared to be little difference in the immunity produced by a single inoculation of 50,000 as compared with 100,000 oöcysts, but inoculation with 100,000 oöcysts, resulted in substantially longer and more severe illness than 50,000 oöcysts. There appeared to be no appreciable difference in clinical symptoms or development of immunity between calves given a single immunizing inoculum and those given the same number of oöcysts in 5 equal inocula on successive days. Treatment with sulfamethazine and sulfamerazine (Merameth) 13 to 15 days after inoculation alleviated the clinical symptoms of coccidiosis without interfering appreciably with the development of immunity. In one experiment with 7 calves, no beneficial effect was noted from 1 or 2 transfusions of 500 ml. of plasma and leucocytes from immune calves into 4 calves 1 and 12 days or 11 days after a challenge inoculation.     

Structure-function analysis of immunity proteins of pediocin-like bacteriocins: C-terminal parts of immunity proteins are involved in specific recognition of cognate bacteriocins

The immunity proteins of pediocin-like bacteriocins show a high degree of specificity with respect to the pediocin-like bacteriocin they recognize and confer immunity to. The aim of this study was to identify regions of the immunity proteins that are involved in this specific recognition. Six different hybrid immunity proteins were constructed from three different pediocin-like bacteriocin immunity proteins that have similar sequences but confer resistance to different bacteriocins. These hybrid immunity proteins were then tested for their ability to confer immunity to various pediocin-like bacteriocins. The specificities of the hybrid immunity proteins proved to be similar to those of the immunity proteins from which the C-terminal halves were derived, thus revealing that the C-terminal half of immunity proteins for pediocin-like bacteriocins contains a domain that is involved in specific recognition of the bacteriocins they confer immunity to. Moreover, the results also revealed that the effectiveness of an immunity protein is strain dependent and that its functionality thus depends in part on interplay with strain-dependent factors. To further investigate the structure-function relationship of these immunity proteins, the enterocin A and leucocin A immunity proteins (EntA-im and LeuA-im) were purified to homogeneity and structurally analyzed under various conditions by Circular dichroism (CD) spectroscopy. The results revealed that both immunity proteins are alpha-helical and well structured in an aqueous environment, the denaturing temperature being 78.5 degrees C for EntA-im and 58.0 degrees C for LeuA-im. The CD spectra also revealed that there was no further increase in the structuring or alpha-helical content when the immunity proteins were exposed to dodecylphosphocholine micelles or dioleoyl-L-alpha-phosphatidyl-DL-glycerol (DOPG) liposomes, indicating that the immunity proteins, in contrast to the bacteriocins, do not interact extensively with membranes. They may nevertheless be loosely associated with the membrane, possibly as peripheral membrane proteins, thus enabling them to interact with their cognate bacteriocin.     

Nucleotide sequences required for Tn3 transposition immunity.

The Tn3 transposon inserts at a reduced frequency into a plasmid already containing a copy of Tn3, a phenomenon known as transposition immunity. The cis-acting site on Tn3 responsible for immunity was mapped by deletions from each side to be within the terminal 38-base-pair sequence that is inversely repeated at the ends of Tn3. Two palindromic sequences are present in the essential part of this region. Some deletions conferred only partial immunity, and others conferred negative immunity. Multiple copies of partially immune ends conferred additional immunity. No other part of Tn3 was necessary for immunity.     

Localization of genes responsible for replication and immunity to colicin A on plasmid ColA-CA31

The region containing the origin and regulatory sites for replication as well as the immunity gene (iaa) have been localized on the plasmid ColA-CA31. The region involved in replication functions of ColA can be hybridized with that of ColE1. It is located between 1 and 1 kb on the plasmid map previously published (Morlon et al. 1982a). A 0.50 Kb HincII fragment of ColA can be weakly hybridized to the ColE1 immunity region. This fragment contains iaa since directed in vitro mutagenesis at an internal restriction site can abolish the immunity to colicin A; however, it does not contain the entire iaa. Knowing the localization of regions involved in autonomous DNA replication and immunity, a mini-ColA plasmid was constructed that contains these two regions. The mini-ColA of 2.8 Kb can be amplified in the presence of chloramphenicol and confers the immunity to transformants. It thus constitutes a useful cloning vector. Expression of ColA and of the various constructed plasmids in the maxicell system suggests that the immunity protein has a molecular weight of about 18-20 Kd.     

Uncoupling of transpositional immunity from gamma delta transposition by a mutation at the end of gamma delta.

The transposon gamma delta, in common with other members of the Tn3 family, confers transpositional immunity, a phenomenon by which plasmids containing a single transposon end show reduced activity as targets for further insertion by the same element. We found that a copy of a mutant delta end, in which the two terminal base pairs (5' GG) were substituted with cytosines, conferred the same degree of immunity as the unaltered delta end. However, a transposon analog with the mutant delta end as its termini could not transpose. These results suggest that the binding of transposase to a site on a target replicon is sufficient to confer immunity and that immunity does not involve subsequent DNA transactions at the bound target site, analogous to the catalytic processes that occur at the transposon ends during transposition.     

The quantitative research of composite immune indicator for crustacean

Through analyzing the immunity indicators in recent crustacean research, two defects are pointed in comprehensive immunity evaluation, 1) the integrant indicators cannot comprehensively reflect the change of immunity, and 2) the conclusions that obtained from different indicators of immunity level cannot be compared objectively and scientifically. Basing on that, the paper firstly indicated that the immunity system could be regarded as a composite indicator. Secondly, the paper gave the specific definition of the composite immunity indicator (CII), and discussed the methods of calculation, especially provided two calculation methods of the weights, that is, the Analytic Hierarchy Process (AHP) and the Principal Component Analysis (PCA). Finally, examples were given to clarify the specific steps to compute the composite immunity indicator. The computing results gave the quantitative evaluation, which were in concordance with the existing conclusions.     

Innate immunity and adjuvants

Innate immunity was for a long time considered to be non-specific because the major function of this system is to digest pathogens and present antigens to the cells involved in acquired immunity. However, recent studies have shown that innate immunity is not non-specific, but is instead sufficiently specific to discriminate self from pathogens through evolutionarily conserved receptors, designated Toll-like receptors (TLRs). Indeed, innate immunity has a crucial role in early host defence against invading pathogens. Furthermore, TLRs were found to act as adjuvant receptors that create a bridge between innate and adaptive immunity, and to have important roles in the induction of adaptive immunity. This paradigm shift is now changing our thinking on the pathogenesis and treatment of infectious, immune and allergic diseases, as well as cancers. Besides TLRs, recent findings have revealed the presence of a cytosolic detector system for invading pathogens. I will review the mechanisms of pathogen recognition by TLRs and cytoplasmic receptors, and then discuss the roles of these receptors in the development of adaptive immunity in response to viral infection.