Sequence of Plasmodium falciparum chromosomes 2, 10, 11 and 14

The mosquito-borne malaria parasite Plasmodium falciparum kills an estimated 0.7-2.7 million people every year, primarily children in sub-Saharan Africa. Without effective interventions, a variety of factors-including the spread of parasites resistant to antimalarial drugs and the increasing insecticide resistance of mosquitoes-may cause the number of malaria cases to double over the next two decades. To stimulate basic research and facilitate the development of new drugs and vaccines, the genome of Plasmodium falciparum clone 3D7 has been sequenced using a chromosome-by-chromosome shotgun strategy. We report here the nucleotide sequences of chromosomes 10, 11 and 14, and a re-analysis of the chromosome 2 sequence. These chromosomes represent about 35% of the 23-megabase P. falciparum genome.     

Caenorhabditis elegans expressed sequence tags identify gene families and potential disease gene homologues.

A database containing mapped partial cDNA sequences from Caenorhabditis elegans will provide a ready starting point for identifying nematode homologues of important human genes and determining their functions in C. elegans. A total of 720 expressed sequence tags (ESTs) have been generated from 585 clones randomly selected from a mixed-stage C. elegans cDNA library. Comparison of these ESTs with sequence databases identified 422 new C. elegans genes, of which 317 are not similar to any sequences in the database. Twenty-six new genes have been mapped by YAC clone hybridization. Members of several gene families, including cuticle collagens, GTP-binding proteins, and RNA helicases were discovered. Many of the new genes are similar to known or potential human disease genes, including CFTR and the LDL receptor.     

Sequence and analysis of chromosome 2 of the plant Arabidopsis thaliana

Arabidopsis thaliana (Arabidopsis) is unique among plant model organisms in having a small genome (130-140 Mb), excellent physical and genetic maps, and little repetitive DNA. Here we report the sequence of chromosome 2 from the Columbia ecotype in two gap-free assemblies (contigs) of 3.6 and 16 megabases (Mb). The latter represents the longest published stretch of uninterrupted DNA sequence assembled from any organism to date. Chromosome 2 represents 15% of the genome and encodes 4,037 genes, 49% of which have no predicted function. Roughly 250 tandem gene duplications were found in addition to large-scale duplications of about 0.5 and 4.5 Mb between chromosomes 2 and 1 and between chromosomes 2 and 4, respectively. Sequencing of nearly 2 Mb within the genetically defined centromere revealed a low density of recognizable genes, and a high density and diverse range of vestigial and presumably inactive mobile elements. More unexpected is what appears to be a recent insertion of a continuous stretch of 75% of the mitochondrial genome into chromosome 2.     

Regional blood flows during desynchronized sleep in the cat

Riassunto Durante il sonno desincronizzato del gatto, non si ha una vasodilatazione generalizzata a tutti i letti vascolari. Mentre il distretto mesenterico si dilata, quello muscolare si costringe. La vasodilatazione viscrale dipende da una diminuita attività simpatica; per la vasocostrizione muscolare, invece, bisogna pensare, oltre che a meccanismi nervosi, anche a fattori meccanici e metabolici.

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This research has been sponsored by Consiglio Nazionale delle Ricerche (Gruppo di Medicina Sperimentale), and by a PHS fellowship to D. B. Adams.     

A direct functional link between the multi-PDZ domain protein GRIP1 and the Fraser syndrome protein Fras1

Cell adhesion to extracellular matrix (ECM) proteins is crucial for the structural integrity of tissues and epithelial-mesenchymal interactions mediating organ morphogenesis. Here we describe how the loss of a cytoplasmic multi-PDZ scaffolding protein, glutamate receptor interacting protein 1 (GRIP1), leads to the formation of subepidermal hemorrhagic blisters, renal agenesis, syndactyly or polydactyly and permanent fusion of eyelids (cryptophthalmos). Similar malformations are characteristic of individuals with Fraser syndrome and animal models of this human genetic disorder, such as mice carrying the blebbed mutation (bl) in the gene encoding the Fras1 ECM protein. GRIP1 can physically interact with Fras1 and is required for the localization of Fras1 to the basal side of cells. In one animal model of Fraser syndrome, the eye-blebs (eb) mouse, Grip1 is disrupted by a deletion of two coding exons. Our data indicate that GRIP1 is required for normal cell-matrix interactions during early embryonic development and that inactivation of Grip1 causes Fraser syndrome-like defects in mice.     

Quantum metallicity in a two-dimensional insulator

One of the most far-reaching problems in condensed-matter physics is to understand how interactions between electrons, and the resulting correlations, affect the electronic properties of disordered two-dimensional systems. Extensive experimental and theoretical studies have shown that interaction effects are enhanced by disorder, and that this generally results in a depletion of the density of electronic states. In the limit of strong disorder, this depletion takes the form of a complete gap in the density of states. It is known that this 'Coulomb gap' can turn a pure metal film that is highly disordered into a poorly conducting insulator, but the properties of these insulators are not well understood. Here we investigate the electronic properties of disordered beryllium films, with the aim of disentangling the effects of the Coulomb gap and the underlying disorder. We show that the gap is suppressed by a magnetic field and that this drives the strongly insulating beryllium films into a low-temperature 'quantum metal' phase with resistance near the quantum resistance RQ = h/e2, where h is Planck's constant and e is the electron charge.     

The Children's Planning Initiative: Researching Decision-Making for Children

This paper recounts the story of how a number of workers involved in the care of children decided that they needed to do more than improve their skills and began instead to question some of the assumptions on which child care planning processes are built. The paper records a growing consciousness about the value of action research in developing alternative models of decision-making. It leads us from early questioning, through model creation, and on into testing the model in a new and complex organizational setting. While other voices are quoted, the paper recounts the story from the viewpoint of two actors, practitioner/manager and consultant.     

High levels of gene flow in the California vole ( Microtus californicus ) are consistent across spatial scales

Gene flow links the genetic and demographic structures of species. Despite the fact that similar genetic and demographic patterns shape both local population structure and regional phylogeography, the 2 levels of population connectivity are rarely studied simultaneously. Here, we studied gene flow in the California vole ( Microtus californicus ), a small-bodied rodent with limited vagility but high local abundance. Within a 4.86-km 2 preserve in central California, genetic diversity in 6 microsatellites was high, and Bayesian methods indicated a single genetic cluster. However, individual-based genetic analysis detected a clear signal for isolation-by-distance (IBD) and fine-scale population structure. Mitochondrial cytochrome b sequencing revealed 11 unique haplotypes from the one local area where we sequenced 62 individuals. Phylogeographic analysis of these individuals combined with those sampled from the northern geographic range of the species (the range of the species spans western North America from southern Oregon to northern Mexico and is centered geographically within the state of California) again indicated a lack of structure but a signal for IBD. Patterns of gene flow thus are consistent across spatial scales: while dispersal of the California vole is limited across geographic distance, there is nonetheless considerable movement across the landscape. We conclude that in this species, high local population abundances overcome the potential genetic and demographic effects of limited dispersal.