抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Summary The Agrobacterium vacuum infiltration method has made it possible to transform Arabidopsis thaliana without plant tissue culture or regeneration. In the present study, this method was evaluated and a substantially modified transformation method was developed. The labor-intensive vacuum infiltration process was eliminated in favor of simple dipping of developing floral tissues into a solution containing Agrobacterium tumefaciens, 5% sucrose and 500 microliters per litre of surfactant Silwet L-77. Sucrose and surfactant were critical to the success of the floral dip method. Plants inoculated when numerous immature floral buds and few siliques were present produced transformed progeny at the highest rate. Plant tissue culture media, the hormone benzylamino purine and pH adjustment were unnecessary, and Agrobacterium could be applied to plants at a range of cell densities. Repeated application of Agrobacterium improved transformation rates and overall yield of transformants approximately twofold. Covering plants for 1 day to retain humidity after inoculation also raised transformation rates twofold. Multiple ecotypes were transformable by this method. The modified method should facilitate high-throughput transformation of Arabidopsis for efforts such as T-DNA

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Floral dip: a simplified method for Agrobacterium-mediated transformation of Arabidopsis thaliana

The physiological and molecular mechanisms of tolerance to osmotic and ionic components of salinity stress are reviewed at the cellular, organ, and whole-plant level. Plant growth responds to salinity in two phases: a rapid, osmotic phase that inhibits growth of young leaves, and a slower, ionic phase that accelerates senescence of mature leaves. Plant adaptations to salinity are of three distinct types: osmotic stress tolerance, Na + or Cl − exclusion, and the tolerance of tissue to accumulated Na + or Cl − . Our understanding of the role of the HKT gene family in Na + exclusion from leaves is increasing, as is the understanding of the molecular bases for many other transport processes at the cellular level. However, we have a limited molecular understanding of the overall control of Na + accumulation and of osmotic stress tolerance at the whole-plant level. Molecular genetics and functional genomics provide a new opportunity to synthesize molecular and physiological knowledge to improve the salinity tolerance of plants relevant to food production and environmental sustainability.

https://rodas5.us.es/file/c2a700e9-8b4a-1970-d343-4a269c302970/1/estres_salino_bibliografia_scorm.zip/files/estres_salino_bibliografia.pdf

Mechanisms of salinity tolerance

The flowering plant Arabidopsis thaliana is an important model system for identifying genes and determining their functions. Here we report the analysis of the genomic sequence of Arabidopsis. The sequenced regions cover 115.4 megabases of the 125-megabase genome and extend into centromeric regions. The evolution of Arabidopsis involved a whole-genome duplication, followed by subsequent gene loss and extensive local gene duplications, giving rise to a dynamic genome enriched by lateral gene transfer from a cyanobacterial-like ancestor of the plastid. The genome contains 25,498 genes encoding proteins from 11,000 families, similar to the functional diversity of Drosophila and Caenorhabditis elegans--the other sequenced multicellular eukaryotes. Arabidopsis has many families of new proteins but also lacks several common protein families, indicating that the sets of common proteins have undergone differential expansion and contraction in the three multicellular eukaryotes. This is the first complete genome sequence of a plant and provides the foundations for more comprehensive comparison of conserved processes in all eukaryotes, identifying a wide range of plant-specific gene functions and establishing rapid systematic ways to identify genes for crop improvement.

/pdf/analysis-of-the-genome-sequence-of-the-flowering-plant-3vizsb52m2.pdf

Analysis of the genome sequence of the flowering plant Arabidopsis thaliana.

Demand has never been greater for revolutionary technologies that deliver fast, inexpensive and accurate genome information. This challenge has catalysed the development of next-generation sequencing (NGS) technologies. The inexpensive production of large volumes of sequence data is the primary advantage over conventional methods. Here, I present a technical review of template preparation, sequencing and imaging, genome alignment and assembly approaches, and recent advances in current and near-term commercially available NGS instruments. I also outline the broad range of applications for NGS technologies, in addition to providing guidelines for platform selection to address biological questions of interest.

/pdf/sequencing-technologies-the-next-generation-599pyrfdla.pdf

Sequencing technologies-the next generation

A method of rapidly producing a double-stranded target DNA is disclosed. The method includes the step of producing multiple single stranded primary DNA constructs having (a) partially overlapping and complementary internal regions that together define the target DNA, and (b) flanking regions on either side of the internal regions containing a PCR primer recognition site and a restriction enzyme recognition site. The primary DNA constructs are amplified to form a pool of double-stranded primary constructs, and a restriction enzyme is used to cleave off the flanking regions. The target double-stranded DNA is then assembled from the cleaved fragments. Hundreds of thousands of oligonucleotides can be synthesized and quickly and efficiently assembled into many different individual double-stranded DNA target sequences using this method.

Methods for rapid production of double-stranded target dna

The present disclosure provides systems and methods for characterizing the interaction of free radicals with various materials and the use of known interactions to isolate free radical generation from free radical interaction with a target molecule.

Methods and systems for transmission and detection of free radicals

The synthesis of arrays of DNA probe sequences, polypeptides and the like is carried out using a patterning process on an active surface of a substrate (12). An image is projected onto the active surface (15) utilizing an image former (11) that includes a light source that provides light to a micromirror device (35) comprising an array of electronically addressable micromirrors (36). The substrate (12) is activated in a defined pattern and bases are coupled at the activated sites, with further repeats until the elements of a two-dimensional array on the substrate have an appropriate base bound thereto. The micromirror array (35) can be controlled in conjunction with a DNA synthesizer to control the sequencing of images presented by the micromirror array (35) in coordination with the reagents provided to the substrate (12).

Method for synthesis of arrays of dna probes

Recent human development of high-level sources of ionizing radiation (IR) prompts a corresponding need to understand the effects of IR on living systems. One approach has focused on the capacity of some organisms to survive astonishing levels of IR exposure. Using experimental evolution, we have generated populations of Escherichia coli with IR resistance comparable to the extremophile Deinococcus radiodurans. Every aspect of cell physiology is affected. Cellular isolates exhibit approximately 1,000 base pair changes plus major genomic and proteomic alterations. The IR resistance phenotype is stable without selection for at least 100 generations. Defined and probable contributions include alterations in cellular systems involved in DNA repair, amelioration of reactive oxygen species, Fe metabolism and repair of iron-sulfur centers, DNA packaging, and intermediary metabolism. A path to new mechanistic discoveries, exemplified by an exploration of rssB function, is evident. Most important, there is no single molecular mechanism underlying extreme IR resistance.

/pdf/experimental-evolution-of-extremophile-levels-of-radiation-1961jzgqpu.pdf

Michael R. Sussman

Papers

Methods for rapid production of double-stranded target dna

Methods and systems for transmission and detection of free radicals

Method for synthesis of arrays of dna probes

Experimental evolution of extremophile levels of radiation resistance in Escherichia coli

Mass spectrometric based analysis of whole eggs dissolved in formic acid.