DNA sequencing of a cytogenetically normal acute myeloid leukaemia genome

Acute myeloid leukaemia is a highly malignant haematopoietic tumour that affects about 13,000 adults in the United States each year. The treatment of this disease has changed little in the past two decades, because most of the genetic events that initiate the disease remain undiscovered. Whole-genome sequencing is now possible at a reasonable cost and timeframe to use this approach for the unbiased discovery of tumour-specific somatic mutations that alter the protein-coding genes. Here we present the results obtained from sequencing a typical acute myeloid leukaemia genome, and its matched normal counterpart obtained from the same patient's skin. We discovered ten genes with acquired mutations; two were previously described mutations that are thought to contribute to tumour progression, and eight were new mutations present in virtually all tumour cells at presentation and relapse, the function of which is not yet known. Our study establishes whole-genome sequencing as an unbiased method for discovering cancer-initiating mutations in previously unidentified genes that may respond to targeted therapies.     

Clonal evolution in relapsed acute myeloid leukaemia revealed by whole-genome sequencing

Most patients with acute myeloid leukaemia (AML) die from progressive disease after relapse, which is associated with clonal evolution at the cytogenetic level. To determine the mutational spectrum associated with relapse, we sequenced the primary tumour and relapse genomes from eight AML patients, and validated hundreds of somatic mutations using deep sequencing; this allowed us to define clonality and clonal evolution patterns precisely at relapse. In addition to discovering novel, recurrently mutated genes (for example, WAC, SMC3, DIS3, DDX41 and DAXX) in AML, we also found two major clonal evolution patterns during AML relapse: (1) the founding clone in the primary tumour gained mutations and evolved into the relapse clone, or (2) a subclone of the founding clone survived initial therapy, gained additional mutations and expanded at relapse. In all cases, chemotherapy failed to eradicate the founding clone. The comparison of relapse-specific versus primary tumour mutations in all eight cases revealed an increase in transversions, probably due to DNA damage caused by cytotoxic chemotherapy. These data demonstrate that AML relapse is associated with the addition of new mutations and clonal evolution, which is shaped, in part, by the chemotherapy that the patients receive to establish and maintain remissions.     

Coherent singlet-triplet oscillations in a silicon-based double quantum dot

Silicon is more than the dominant material in the conventional microelectronics industry: it also has potential as a host material for emerging quantum information technologies. Standard fabrication techniques already allow the isolation of single electron spins in silicon transistor-like devices. Although this is also possible in other materials, silicon-based systems have the advantage of interacting more weakly with nuclear spins. Reducing such interactions is important for the control of spin quantum bits because nuclear fluctuations limit quantum phase coherence, as seen in recent experiments in GaAs-based quantum dots. Advances in reducing nuclear decoherence effects by means of complex control still result in coherence times much shorter than those seen in experiments on large ensembles of impurity-bound electrons in bulk silicon crystals. Here we report coherent control of electron spins in two coupled quantum dots in an undoped Si/SiGe heterostructure and show that this system has a nuclei-induced dephasing time of 360 nanoseconds, which is an increase by nearly two orders of magnitude over similar measurements in GaAs-based quantum dots. The degree of phase coherence observed, combined with fast, gated electrical initialization, read-out and control, should motivate future development of silicon-based quantum information processors.     

Localization of cystic fibrosis locus to human chromosome 7cen-q22

Cystic fibrosis (CF) is the most common genetic disease in Caucasian populations, with an incidence of 1 in 2,000 live births in the United Kingdom, and a carrier frequency of approximately 1 in 20. The biochemical basis of the disease is not known, although membrane transport phenomena associated with CF have been described recently. Consanguinity studies have shown that the inheritance of CF is consistent with it being a recessive defect caused by a mutation at a single autosomal locus. Eiberg et al. have reported a genetic linkage between the CF locus and a polymorphic locus controlling activity of the serum aryl esterase paraoxonase (PON). The chromosomal location of PON, however, is not known. Linkage to a DNA probe, DOCR1-917, was also recently found at a genetic distance of approximately 15 centimorgans (L.-C. Tsui and H. Donnis-Keller, personal communication), but no chromosomal localization was given. Here we report tight linkage between the CF locus and an anonymous DNA probe, pJ3.11, which has been assigned to chromosome 7cen-q22.     

Microorganisms seen by scanning and transmission electron microscopy in Legionnaires' disease from human lung.

In addition to several anomalous structures, other general forms of definitely rod-shaped microorganisms have been found by scanning and transmission electron microscopy in the lung tissue taken at autopsy from a patient who succumbed to confirmed Legionnaires' disease with extensive necrotizing lobar pneumonia. The microorganisms were greatly varied in size and shape. They were micrographed in the act of fission. These forms have been found to some extent throughout the tissue. No nickel was demonstrated, either in the lung tissue or in the microorganisms.     

Lack of effects of 5-HT3 antagonists on normal and morphine-attenuated sexual behaviours in female and male rats

Although 5-HT₁ and 5-HT₂ receptor activity is known to influence copulation, the effects of 5-HT₃ receptor-selective drugs on sexual activity have yet to be systematically studied. The following experiments investigated the effects of the 5-HT₃-selective antagonists MDL 72222, ondansetron and ICS 205-930 on female sexual behaviour; male rats were studied using ondansetron and granisetron. These compounds influenced neither male nor female copulatory behaviours, suggesting that 5-HT₃ receptors contribute little to the modulation of sexual activity. 5-HT₃ receptor antagonists block certain opioid-induced behaviours and opioids selectively inhibit sexual behaviours; therefore, the ability of ondansetron and ICS 205-930 to modify morphine-attenuated copulatory activity was also tested. While morphine inhibited copulation, 5-HT₃ antagonists failed to reverse the effects.     

Preventing a population decline of red grouse (Lagopus lagopus scoticus) by manipulating density

Summary This experiment tested whether a cyclic-type population decline can be prevented by removing territorial cock red grouse to keep breeding density below peak levels. The manipulated population did not decline, despite big decreases in food and breeding success, and more parasitic threadworms per bird than on the control.     

Chromogenicity ofSakagughi products of monosubstituted guanidines and histidine

Zusammenfassung Es werden neue Beobachtungen über die Zweckmässigkeit derSakaguchi-Farbreaktion für Arginin mitgeteilt: Aminosäuren, die die Farbreaktion gewöhnlich hindern, wirken in niedriger Quantität (0,05 bis 0,2M) verstärkend. Histidin ergibt eine positiveSakaguchi-Reaktion.     

The trophic fingerprint of marine fisheries

Biodiversity indicators provide a vital window on the state of the planet, guiding policy development and management. The most widely adopted marine indicator is mean trophic level (MTL) from catches, intended to detect shifts from high-trophic-level predators to low-trophic-level invertebrates and plankton-feeders. This indicator underpins reported trends in human impacts, declining when predators collapse ("fishing down marine food webs") and when low-trophic-level fisheries expand ("fishing through marine food webs"). The assumption is that catch MTL measures changes in ecosystem MTL and biodiversity. Here we combine model predictions with global assessments of MTL from catches, trawl surveys and fisheries stock assessments and find that catch MTL does not reliably predict changes in marine ecosystems. Instead, catch MTL trends often diverge from ecosystem MTL trends obtained from surveys and assessments. In contrast to previous findings of rapid declines in catch MTL, we observe recent increases in catch, survey and assessment MTL. However, catches from most trophic levels are rising, which can intensify fishery collapses even when MTL trends are stable or increasing. To detect fishing impacts on marine biodiversity, we recommend greater efforts to measure true abundance trends for marine species, especially those most vulnerable to fishing.