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

1. Plant Nutrients. 2. The Soil as a Plant Nutrient Medium. 3. Nutrient Uptake and Assimilation. 4. Plant Water Relationships. 5. Plant Growth and Crop Production. 6. Fertilizer Application. 7. Nitrogen. 8. Sulphur. 9. Phosphorus. 10. Potassium. 11. Calcium. 12. Magnesium. 13. Iron. 14. Manganese. 15. Zinc. 16. Copper. 17. Molybdenum. 18. Boron. 19. Further Elements of Importance. 20. Elements with More Toxic Effects. General Readings. References. Index.

/pdf/principles-of-plant-nutrition-2k4wl46ou6.pdf

Principles of plant nutrition

The glutathione S-transferases (GST) represent a major group of detoxification enzymes. All eukaryotic species possess multiple cytosolic and membrane-bound GST isoenzymes, each of which displays distinct catalytic as well as noncatalytic binding properties: the cytosolic enzymes are encoded by at least five distantly related gene families (designated class alpha, mu, pi, sigma, and theta GST), whereas the membrane-bound enzymes, microsomal GST and leukotriene C, synthetase, are encoded by single genes and both have arisen separately from the soluble GST. Evidence suggests that the level of expression of GST is a crucial factor in determining the sensitivity of cells to a broad spectrum of toxic chemicals. In this article the biochemical functions of GST are described to show how individual isoenzymes contribute to resistance to carcinogens, antitumor drugs, environmental pollutants, and products of oxidative stress.A description of the mechanisms of transcriptional and posttranscriptional regulat...

The glutathione S-transferase supergene family: regulation of GST and the contribution of the isoenzymes to cancer chemoprotection and drug resistance.

The role of flavonoids as the major red, blue, and purple pigments in plants has gained these secondary products a great deal of attention over the years. From the first description of acid and base effects on plant pigments by Robert Boyle in 1664 to the characterization of structural and

Flavonoid Biosynthesis. A Colorful Model for Genetics, Biochemistry, Cell Biology, and Biotechnology

Small GTP-binding proteins (G proteins) exist in eukaryotes from yeast to human and constitute a superfamily consisting of more than 100 members. This superfamily is structurally classified into at least five families: the Ras, Rho, Rab, Sar1/Arf, and Ran families. They regulate a wide variety of cell functions as biological timers (biotimers) that initiate and terminate specific cell functions and determine the periods of time for the continuation of the specific cell functions. They furthermore play key roles in not only temporal but also spatial determination of specific cell functions. The Ras family regulates gene expression, the Rho family regulates cytoskeletal reorganization and gene expression, the Rab and Sar1/Arf families regulate vesicle trafficking, and the Ran family regulates nucleocytoplasmic transport and microtubule organization. Many upstream regulators and downstream effectors of small G proteins have been isolated, and their modes of activation and action have gradually been elucidated. Cascades and cross-talks of small G proteins have also been clarified. In this review, functions of small G proteins and their modes of activation and action are described.

Small GTP-Binding Proteins

Plant Signaling: HY5 Synchronizes Resource Supply.

In eucaryotic cells external signals detected by receptors are translated into a limited repertoire of intracellular second messengers. Occupancy of these receptors initiates the production of active messengers, including the well studied cyclic adenosine monophosphate (cAMP) as well as the recently discovered messenger molecules that are derived from phosphoinositides such as arachidonic acid, inositol-l,4,5-triphosphate, and 1,2-diacylglycerol (for review see: Berridge 1986; Newton and Brown 1986; Boss and Morre 1989). These messengers are capable of regulating a vast array of physiological and biochemical processes either by direct interaction with distinct proteins or indirectly by activating enzymes which trigger conformational changes in the final target proteins. However, the number of second messengers in eucaryotic cells appears to be surprisingly small, indicating that most probably only a limited number of internal signal pathways are needed, albeit remarkably universally in all eucaryotes analyzed up to now, to transduce these signals to their final biological destination.

Signalling Elements in Higher Plants: Identification and Molecular Analysis of an Auxin-Binding Protein, GTP-Binding Regulatory Proteins and Calcium Sensitive Proteins

Recent advances in the search for genes involved in the mecahnisms of action of auxin and cytokinins

Background
Absorption and refraction induced signal attenuation can seriously hinder the extraction of quantitative information from confocal microscopic data. This signal attenuation can be estimated and corrected by algorithms that use physical image formation models. Especially in thick heterogeneous samples, current single view based models are unable to solve the underdetermined problem of estimating the attenuation-free intensities.

/pdf/variational-attenuation-correction-in-two-view-confocal-2fqfnbd4b2.pdf

Klaus Palme

Papers

Plant Signaling: HY5 Synchronizes Resource Supply.

Signalling Elements in Higher Plants: Identification and Molecular Analysis of an Auxin-Binding Protein, GTP-Binding Regulatory Proteins and Calcium Sensitive Proteins

Recent advances in the search for genes involved in the mecahnisms of action of auxin and cytokinins

Variational attenuation correction in two-view confocal microscopy

On plant growth regulators and their metabolites: a changing perspective.