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

The results of a single-crystal structure determination when in CIF format can now be validated routinely by automatic procedures. In this way, many errors in published papers can be avoided. The validation software generates a set of ALERTS detailing issues to be addressed by the experimenter, author, referee and publication journal. Validation was pioneered by the IUCr journal Acta Crystallographica Section C and is currently standard procedure for structures submitted for publication in all IUCr journals. The implementation of validation procedures by other journals is in progress. This paper describes the concepts of validation and the classes of checks that are carried out by the program PLATON as part of the IUCr checkCIF facility. PLATON validation can be run at any stage of the structure refinement, independent of the structure determination package used, and is recommended for use as a routine tool during or at least at the completion of every structure determination. Two examples are discussed where proper validation procedures could have avoided the publication of incorrect structures that had serious consequences for the chemistry involved.

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Single-crystal structure validation with the program PLATON

Statistical method for testing the neutral mutation hypothesis by DNA polymorphism.

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

So far in this course we have dealt entirely with the evolution of characters that are controlled by simple Mendelian inheritance at a single locus. There are notes on the course website about gametic disequilibrium and how allele frequencies change at two loci simultaneously, but we didn’t discuss them. In every example we’ve considered we’ve imagined that we could understand something about evolution by examining the evolution of a single gene. That’s the domain of classical population genetics. For the next few weeks we’re going to be exploring a field that’s actually older than classical population genetics, although the approach we’ll be taking to it involves the use of population genetic machinery. If you know a little about the history of evolutionary biology, you may know that after the rediscovery of Mendel’s work in 1900 there was a heated debate between the “biometricians” (e.g., Galton and Pearson) and the “Mendelians” (e.g., de Vries, Correns, Bateson, and Morgan). Biometricians asserted that the really important variation in evolution didn’t follow Mendelian rules. Height, weight, skin color, and similar traits seemed to

Human biochemical genetics

Human methionine aminopeptidase type 2 in complex with L- and D-methionine.

Diatoms are photosynthetic microalgae that fix a significant fraction of the world's carbon. Because of their photosynthetic efficiency and high-lipid content, diatoms are priority candidates for biofuel production. Here, we report that sporulating Bacillus thuringiensis and other members of the Bacillus cereus group, when in co-culture with the marine diatom Phaeodactylum tricornutum, significantly increase diatom cell count. Bioassay-guided purification of the mother cell lysate of B. thuringiensis led to the identification of two diketopiperazines (DKPs) that stimulate both P. tricornutum growth and increase its lipid content. These findings may be exploited to enhance P. tricornutum growth and microalgae-based biofuel production. As increasing numbers of DKPs are isolated from marine microbes, the work gives potential clues to bacterial-produced growth factors for marine microalgae.

Bacterial diketopiperazines stimulate diatom growth and lipid accumulation.

Conjugate phenylselenolactonization coupled with allylic selenoxide rearrangement for functionalizing dienylacetic acids

Molecular structure and absolute configuration of alkaloids related to 5,10-ethanophenanthridine

Pantocin A and pantocin B are low-molecular weight, peptide-based antibiotics that are produced in minimal media by the biocontrol agent Pantoea agglomerans, which are inhibitory to the fire blight pathogen, Erwinia amylovora. Pantocin A and pantocin B are members of a family of antibiotics whose toxicity is inhibited by certain amino acids. They inhibit enzymes in pathways for histidine and arginine biosynthesis, respectively. The biosynthetic gene cluster for pantocin A was sequenced, and it is 2.84 kb in size. It contains a small gene (paaP) that encodes a thirty-amino acid precursor peptide and three genes, paaA, paaB and paaC that encode the enzymes necessary to process the precursor into pantocin A. PaaC is proposed to be responsible for resistance to pantocin A. The determinants for pantocin B biosynthesis are encoded in a cluster of 13 open reading frames (PabA through pabM within a 17.5 kb region. Functions are proposed for the individual gene products, based on DNA sequence homology and on the chemical structure of pantocin B. PabA is similar to multidrug resistance proteins (like YqjV of Bacmus subtilis) and is likely responsible for pantocin B resistance. However, pabB, pabC and pabD may also encode resistance determinants. The products of the pabJKLM operon are believed to be involved in the addition of the methyl sulfonyl moiety of pantocin B. Cryptic transposase genes are found within and outside of the biosynthetic region, and the G+C ratio is lower inside than outside of the cluster. Thus, the pantocin B biosynthetic region may be a genomic island whose DNA originated from other organisms and was generated through two separate transposition events.

Jon Clardy

Papers

Human methionine aminopeptidase type 2 in complex with L- and D-methionine.

Bacterial diketopiperazines stimulate diatom growth and lipid accumulation.

Conjugate phenylselenolactonization coupled with allylic selenoxide rearrangement for functionalizing dienylacetic acids

Molecular structure and absolute configuration of alkaloids related to 5,10-ethanophenanthridine

The Biosynthetic genes of pantocin A and pantocin B of Pantoea agglomerans Eh318