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

We describe a new computer program, SnpEff, for rapidly categorizing the effects of variants in genome sequences. Once a genome is sequenced, SnpEff annotates variants based on their genomic locations and predicts coding effects. Annotated genomic locations include intronic, untranslated region, upstream, downstream, splice site, or intergenic regions. Coding effects such as synonymous or non-synonymous amino acid replacement, start codon gains or losses, stop codon gains or losses, or frame shifts can be predicted. Here the use of SnpEff is illustrated by annotating ~356,660 candidate SNPs in ~117 Mb unique sequences, representing a substitution rate of ~1/305 nucleotides, between the Drosophila melanogaster w1118; iso-2; iso-3 strain and the reference y1; cn1 bw1 sp1 strain. We show that ~15,842 SNPs are synonymous and ~4,467 SNPs are non-synonymous (N/S ~0.28). The remaining SNPs are in other categories, such as stop codon gains (38 SNPs), stop codon losses (8 SNPs), and start codon gains (297 SNPs) in...

A program for annotating and predicting the effects of single nucleotide polymorphisms, SnpEff: SNPs in the genome of Drosophila melanogaster strain w1118; iso-2; iso-3

The Insects has been the standard textbook in the field since the first edition published over forty years ago. Building on the strengths of Chapman's original text, this long-awaited 5th edition has been revised and expanded by a team of eminent insect physiologists, bringing it fully up-to-date for the molecular era. The chapters retain the successful structure of the earlier editions, focusing on particular functional systems rather than taxonomic groups and making it easy for students to delve into topics without extensive knowledge of taxonomy. The focus is on form and function, bringing together basic anatomy and physiology and examining how these relate to behaviour. This, combined with nearly 600 clear illustrations, provides a comprehensive understanding of how insects work. Now also featuring a richly illustrated prologue by George McGavin, this is an essential text for students, researchers and applied entomologists alike.

The insects: structure and function.

We review the physiological, molecular, and neural mechanisms of insect color vision. Phylogenetic and molecular analyses reveal that the basic bauplan, UV-blue-green-trichromacy, appears to date back to the Devonian ancestor of all pterygote insects. There are variations on this theme, however. These concern the number of color receptor types, their differential expression across the retina, and their fine tuning along the wavelength scale. In a few cases (but not in many others), these differences can be linked to visual ecology. Other insects have virtually identical sets of color receptors despite strong differences in lifestyle. Instead of the adaptionism that has dominated visual ecology in the past, we propose that chance evolutionary processes, history, and constraints should be considered. In addition to phylogenetic analyses designed to explore these factors, we suggest quantifying variance between individuals and populations and using fitness measurements to test the adaptive value of traits identified in insect color vision systems.

The evolution of color vision in insects.

Analysis of Development Edited by Prof Benjamin H Willier, Prof Paul A Weiss and Prof Viktor Hamburger Pp xii + 735 (Philadelphia and London: W B Saunders Company, 1955) 105s

Mechanisms of Development

Neuroanatomy of the zebrafish brain

1 Introduction: neuroanatomy for a neurogenetic model system.- Differentiation of first neurons and their associated tracts and commissures in the embryonic zebrafish brain.- Neuromeres and expression of regulatory genes in the embryonic zebrafish.- Generation of zebrafish mutants via saturation mutagenesis.- 2 Taxonomic background.- 3 Technical details.- Histology.- Preparation of figures.- 4 The brain of the zebrafish Danio rerio: an overview.- Telencephalon.- Olfactory bulbs.- Area ventralis telencephali.- Area dorsalis telencephali.- Telencephalic tracts and commissures.- Diencephalon (including synencephalon and pretectum).- Area praeoptica.- Epithalamus.- Dorsal thalamus.- Ventral thalamus.- Posterior tuberculum.- Hypothalamus.- Synencephalon.- Pretectum.- Diencephalic tracts and commissures.- Mesencephalon.- Tectum opticum.- Torus semicircularis.- Tegmentum.- Rhombencephalon (metencephalon and myelencephalon).- Cerebellum.- Medulla oblongata.- Primary sensory and motor nuclei.- Reticular formation.- Additional medullary nuclei.- Medulla spinalis.- Brain stem/spinal tracts and commissures.- 5 The brain of the zebrafish Danio rerio: a neuroanatomical atlas.- External view.- Cross sections.- Sagittal sections.- Horizontal sections.- 6 Functional anatomy of the zebrafish brain: a comparative evaluation.- Sensory Systems in the teleostean CNS.- Olfaction.- Vision.- Mechanoreception.- Audition.- Vestibular sense.- Gustation.- General visceral sense.- Somatosensory system.- Motor and premotor systems in the teleostean CNS.- Motor nuclei of cranial nerves.- Descending spinal projections.- Reticular formation.- Integrative centers in the teleostean CNS.- Cerebellum.- Tectum opticum.- Telencephalon.- 7 Index of Latin terms.- 8 Index of English terms.- 9 Index of abbreviations.- 10 References.

Neuroanatomy of the Zebrafish Brain: A Topological Atlas

In the mammalian brain, neural stem cells divide asymmetrically and often amplify the number of progeny they generate via symmetrically dividing intermediate progenitors. Here we investigate whether specific neural stem cell-like neuroblasts in the brain of Drosophila might also amplify neuronal proliferation by generating symmetrically dividing intermediate progenitors. Cell lineage-tracing and genetic marker analysis show that remarkably large neuroblast lineages exist in the dorsomedial larval brain of Drosophila. These lineages are generated by brain neuroblasts that divide asymmetrically to self renew but, unlike other brain neuroblasts, do not segregate the differentiating cell fate determinant Prospero to their smaller daughter cells. These daughter cells continue to express neuroblast-specific molecular markers and divide repeatedly to produce neural progeny, demonstrating that they are proliferating intermediate progenitors. The proliferative divisions of these intermediate progenitors have novel cellular and molecular features; they are morphologically symmetrical, but molecularly asymmetrical in that key differentiating cell fate determinants are segregated into only one of the two daughter cells. Our findings provide cellular and molecular evidence for a new mode of neurogenesis in the larval brain of Drosophila that involves the amplification of neuroblast proliferation through intermediate progenitors. This type of neurogenesis bears remarkable similarities to neurogenesis in the mammalian brain, where neural stem cells as primary progenitors amplify the number of progeny they generate through generation of secondary progenitors. This suggests that key aspects of neural stem cell biology might be conserved in brain development of insects and mammals.

/pdf/amplification-of-neural-stem-cell-proliferation-by-1gicgtptuj.pdf

Amplification of neural stem cell proliferation by intermediate progenitor cells in Drosophila brain development

Brain development in Drosophila is characterized by two neurogenic periods, one during embryogenesis and a second during larval life. Although much is known about embryonic neurogenesis, little is known about the genetic control of postembryonic brain development. Here we use mosaic analysis with a repressible cell marker (MARCM) to study the role of the brain tumor (brat) gene in neural proliferation control and tumour suppression in postembryonic brain development of Drosophila. Our findings indicate that overproliferation in brat mutants is due to loss of proliferation control in the larval central brain and not in the optic lobe. Clonal analysis indicates that the brat mutation affects cell proliferation in a cell-autonomous manner and cell cycle marker expression shows that cells of brat mutant clones show uncontrolled proliferation, which persists into adulthood. Analysis of the expression of molecular markers, which characterize cell types in wild-type neural lineages, indicates that brat mutant clones comprise an excessive number of cells, which have molecular features of undifferentiated progenitor cells that lack nuclear Prospero (Pros). pros mutant clones phenocopy brat mutant clones in the larval central brain, and targeted expression of wild-type pros in brat mutant clones promotes cell cycle exit and differentiation of brat mutant cells, thereby abrogating brain tumour formation. Taken together, our results provide evidence that the tumour suppressor brat negatively regulates cell proliferation during larval central brain development of Drosophila, and suggest that Prospero acts as a key downstream effector of brat in cell fate specification and proliferation control.

/pdf/the-brain-tumor-gene-negatively-regulates-neural-progenitor-2739mfejwv.pdf

Heinrich Reichert

Papers

Neuroanatomy of the zebrafish brain

Neuroanatomy of the Zebrafish Brain: A Topological Atlas

Amplification of neural stem cell proliferation by intermediate progenitor cells in Drosophila brain development

The brain tumor gene negatively regulates neural progenitor cell proliferation in the larval central brain of Drosophila.

Developmental defects in brain segmentation caused by mutations of the homeobox genes orthodenticle and empty spiracles in Drosophila