Description : The ciliate Tetrahymena thermophila is a model organism for molecular and cellular biology. Like other ciliates, this species has separate germline and soma functions that are embodied by distinct nuclei within a single cell. The germline-like micronucleus (MIC) has its genome held in reserve for sexual reproduction. The soma-like macronucleus (MAC), which possesses a genome processed from that of the MIC, is the center of gene expression and does not direc...
Description : The infectious cycle of primate lentiviruses is intimately linked to interactions between cells of the immune system. Nef, a potent virulence factor, alters cellular environments to increase lentiviral replication in the host, yet the mechanisms underlying these effects have remained elusive. Since Nef likely functions as an adaptor protein, we exploited a proteomic approach to directly identify molecules that Nef targets to subvert the signaling machinery ...
Description : A synergistic combination of two next-generation sequencing platforms with a detailed comparative BAC physical contig map provided a cost-effective assembly of the genome sequence of the domestic turkey (Meleagris gallopavo). Heterozygosity of the sequenced source genome allowed discovery of more than 600,000 high quality single nucleotide variants. Despite this heterozygosity, the current genome assembly (,1.1 Gb) includes 917 Mb of sequence assigned to sp...
Description : Signaling from endosomes is emerging as a mechanism by which selected receptors provide sustained signals distinct from those generated at the plasma membrane. The activity of natural killer (NK) cells, which are important effectors of innate immunity and regulators of adaptive immunity, is controlled primarily by receptors that are at the cell surface. Here we show that cytokine secretion by resting human NK cells is induced by soluble, but not solid-phase...
Description : Alternative splicing in mammalian cells has been suggested to be largely controlled by combinatorial binding of basal splicing factors to pre-mRNA templates. This model predicts that distinct sets of pre-mRNA splicing factors are associated with alternatively spliced transcripts. However, no experimental evidence for differential recruitment of splicing factors to transcripts with distinct splicing fates is available. Here we have used quantitative single-c...
Description : An estimated 10% of all human genetic diseases are caused by nonsense mutations. These look like the stop codons that occur naturally at the ends of protein coding sequences in our genomes, but they arise instead in the middle of the protein code, with potentially devastating consequences. Instead of faithfully trundling along a gene transcript, translating it into a useful protein product, the ribosome stops dead in its tracks, leaving the protein incomple...
Description : Insect seminal fluid proteins are powerful modulators of many aspects of female physiology and behaviour including longevity, egg production, sperm storage, and remating. The crucial role of these proteins in reproduction makes them promising targets for developing tools aimed at reducing the population sizes of vectors of disease. In the malaria mosquito Anopheles gambiae, seminal secretions produced by the male accessory glands (MAGs) are transferred to f...
Description : The nematode Caenorhabditis elegans has complex, naturally variable behavioral responses to environmental oxygen, food, and other animals. C. elegans detects oxygen through soluble guanylate cyclase homologs (sGCs) and responds to it differently depending on the activity of the neuropeptide receptor NPR-1 : npr-1(lf) and naturally isolated npr- 1(215F) animals avoid high oxygen and aggregate in the presence of food: npr-1(215V) animals do not. We show here ...
Description : In this century, increasing concentrations of carbon dioxide (CO2) and other greenhouse gases in the Earth’s atmosphere are expected to cause warmer surface temperatures and changes in precipitation patterns. At the same time, reactive nitrogen is entering natural systems at unprecedented rates. These global environmental changes have consequences for the functioning of natural ecosystems, and responses of these systems may feed back to affect climate and a...
Description : Abscisic acid (ABA) signal transduction has been proposed to utilize cytosolic Ca2þ in guard cell ion channel regulation. However, genetic mutants in Ca2þ sensors that impair guard cell or plant ion channel signaling responses have not been identified, and whether Ca2þ-independent ABA signaling mechanisms suffice for a full response remains unclear. Calcium-dependent protein kinases (CDPKs) have been proposed to contribute to central signal transduction res...
Description : DNA damage recognition by the nucleotide excision repair pathway requires an initial step identifying helical distortions in the DNA and a proofreading step verifying the presence of a lesion. This proofreading step is accomplished in eukaryotes by the TFIIH complex. The critical damage recognition component of TFIIH is the XPD protein, a DNA helicase that unwinds DNA and identifies the damage. Here, we describe the crystal structure of an archaeal XPD prot...
Description : Saccharomyces cerevisiae Scc2 binds Scc4 to form an essential complex that loads cohesin onto chromosomes. The prevalence of Scc2 orthologs in eukaryotes emphasizes a conserved role in regulating sister chromatid cohesion, but homologs of Scc4 have not hitherto been identified outside certain fungi. Some metazoan orthologs of Scc2 were initially identified as developmental gene regulators, such as Drosophila Nipped-B, a regulator of cut and Ultrabithorax, a...
Description : We have solved the three-dimensional crystal structure of the stem-loop II motif (s2m) RNA element of the SARS virus genome to 2.7-A° resolution. SARS and related coronaviruses and astroviruses all possess a motif at the 39 end of their RNA genomes, called the s2m, whose pathogenic importance is inferred from its rigorous sequence conservation in an otherwise rapidly mutable RNA genome. We find that this extreme conservation is clearly explained by the requ...
Description : Very little is known about how environmental changes such as increasing temperature affect disease dynamics in the ocean, especially at large spatial scales. We asked whether the frequency of warm temperature anomalies is positively related to the frequency of coral disease across 1,500 km of Australia’s Great Barrier Reef. We used a new highresolution satellite dataset of ocean temperature and 6 y of coral disease and coral cover data from annual surveys o...
Description : The HMG-box factor Tcf1 is required during T-cell development in the thymus and mediates the nuclear response to Wnt signals. Tcf12/2 mice have previously been characterized and show developmental blocks at the CD42CD82 double negative (DN) to CD4+CD8+ double positive transition. Due to the blocks in T-cell development, Tcf12/2 mice normally have a very small thymus. Unexpectedly, a large proportion of Tcf12/2 mice spontaneously develop thymic lymphomas wit...
Description : Differentiated mammary epithelium shows apicobasal polarity, and loss of tissue organization is an early hallmark of breast carcinogenesis. In BRCA1 mutation carriers, accumulation of stem and progenitor cells in normal breast tissue and increased risk of developing tumors of basal-like type suggest that BRCA1 regulates stem/progenitor cell proliferation and differentiation. However, the function of BRCA1 in this process and its link to carcinogenesis remai...