Identification of a histone acetyltransferase as a novel regulator of Drosophila intestinal stem cells

AbstractOne of the major challenges in stem cell research is to decipher the controlling mechanisms/genes of stem cell homeostasis. Through an RNAi mediated genetic screen of living animals, we identified an evolutionarily conserved histone acetyltransferase Atac2 as a novel regulator of Drosophila intestinal stem cells (ISCs). Expression of Atac2-RNAi or a dominant negative allele of Atac2 generated more ISCs, while excessive Atac2 or a histone deacetylase inhibitor promoted ISC differentiation without affecting ISC survival or lineage specification. These findings extend our knowledge of epigenetic mechanisms in stem cell regulation

Result Diversification in Search and Recommendation: A Survey

Diversifying return results is an important research topic in retrieval systems in order to satisfy both the various interests of customers and the equal market exposure of providers. There has been growing attention on diversity-aware research during recent years, accompanied by a proliferation of literature on methods to promote diversity in search and recommendation. However, diversity-aware studies in retrieval systems lack a systematic organization and are rather fragmented. In this survey, we are the first to propose a unified taxonomy for classifying the metrics and approaches of diversification in both search and recommendation, which are two of the most extensively researched fields of retrieval systems. We begin the survey with a brief discussion of why diversity is important in retrieval systems, followed by a summary of the various diversity concerns in search and recommendation, highlighting their relationship and differences. For the survey's main body, we present a unified taxonomy of diversification metrics and approaches in retrieval systems, from both the search and recommendation perspectives. In the later part of the survey, we discuss the open research questions of diversity-aware research in search and recommendation in an effort to inspire future innovations and encourage the implementation of diversity in real-world systems.Comment: 20 page

Implementation of trait-based ozone plant sensitivity in the Yale interactive terrestrial biosphere model v1.0 to assess global vegetation damage

A major limitation in modeling global ozone (O3) vegetation damage has long been the reliance on empiri- cal O3 sensitivity parameters derived from a limited num- ber of species and applied at the level of plant functional types (PFTs), which ignore the large interspecific variations within the same PFT. Here, we present a major advance in large-scale assessments of O3 plant injury by linking the trait leaf mass per area (LMA) and plant O3 sensitivity in a broad and global perspective. Application of the new ap- proach and a global LMA map in a dynamic global veg- etation model reasonably represents the observed interspe- cific responses to O3 with a unified sensitivity parameter for all plant species. Simulations suggest a contemporary global mean reduction of 4.8 % in gross primary productivity by O3, with a range of 1.1 %–12.6 % for varied PFTs. Hotspots with damage > 10 % are found in agricultural areas in the eastern US, western Europe, eastern China, and India, accompanied by moderate to high levels of surface O3. Furthermore, we simulate the distribution of plant sensitivity to O3, which is highly linked with the inherent leaf trait trade-off strategies of plants, revealing high risks for fast-growing species with low LMA, such as crops, grasses, and deciduous trees

Rainbow: reliable personally identifiable information retrieval across multi-cloud

Abstract Personally identifiable information (PII) refers to any information that links to an individual. Sharing PII is extremely useful in public affairs yet hard to implement due to the worries about privacy violations. Building a PII retrieval service over multi-cloud, which is a modern strategy to make services stable where multiple servers are deployed, seems to be a promising solution. However, three major technical challenges remain to be solved. The first is the privacy and access control of PII. In fact, each entry in PII can be shared to different users with different access rights. Hence, flexible and fine-grained access control is needed. Second, a reliable user revocation mechanism is required to ensure that users can be revoked efficiently, even if few cloud servers are compromised or collapse, to avoid data leakage. Third, verifying the correctness of received PII and locating a misbehaved server when wrong data are returned is crucial to guarantee user’s privacy, but challenging to realize. In this paper, we propose Rainbow, a secure and practical PII retrieval scheme to solve the above issues. In particular, we design an important cryptographic tool, called Reliable Outsourced Attribute Based Encryption (ROABE) which provides data privacy, flexible and fine-grained access control, reliable immediate user revocation and verification for multiple servers simultaneously, to support Rainbow. Moreover, we present how to build Rainbow with ROABE and several necessary cloud techniques in real world. To evaluate the performance, we deploy Rainbow on multiple mainstream clouds, namely, AWS, GCP and Microsoft Azure, and experiment in browsers on mobile phones and computers. Both theoretical analysis and experimental results indicate that Rainbow is secure and practical

Genetic characterization of the Drosophila birt-hogg-dubé syndrome gene.

Folliculin (FLCN) is a conserved tumor suppressor gene whose loss is associated with the human Birt-Hogg-Dubé (BHD) syndrome. However, its molecular functions remain largely unknown. In this work, we generated a Drosophila BHD model through genomic deletion of the FLCN gene (DBHD(-) ). The DBHD mutant larvae grew slowly and stopped development before pupation, displaying various characteristics of malnutrition. We found the growth delay was sensitive to the nutrient supplies. It became more severe upon restrictions of the dietary yeast; while high levels of yeast significantly restored the normal growth, but not viability. We further demonstrated that leucine was able to substitute for yeast to provide similar rescues. Moreover, the human FLCN could partially rescue the DBHD(-) phenotypes, indicating the two genes are involved in certain common mechanisms. Our work provides a new animal model of the BHD syndrome and suggests that modulation of the local nutrient condition might be a potential treatment of the BHD lesions

Mitosis and endoreplication are suppressed in <i>DBHD^−/−</i> larvae.

<p>PH3 marks the mitotic cells. EdU marks the cells undergoing DNA synthesis. DAPI marks the nuclei. (A and B): Eye imaginal discs. (C, D, K, L): Brains. (E, F, I, J): Fat bodies. (G and H): Salivary glands. The sibling heterozygotes (−/+) were taken as the wild-type controls. Note all the <i>DBHD^−/−</i> samples (−/−) are reduced in size, the polyploidy are also reduced in cells from fat body (F) and salivary gland (H).</p

Autophagy is elevated in the <i>DBHD^−/−</i> larvae.

<p>(A–C) LysoTracker staining (red) of unfixed larval fat bodies. The GFP-positive tissues (green) are from heterozygotes (<i>Kr::GFP</i>). (A) The LysoTracker signal is much stronger in the <i>DBHD^−/−</i> (−/−) fat bodies than in the heterozygotes (−/+). The 4-day-old larvae were picked form the same food vial, processed in the same staining tube and imagined in one optical field. (B) LysoTracker signal became strong in the heterozygotes starved for 3 hours by supplying with distilled water only. The same staining of fat body from starved <i>DBHD^−/−</i> is also shown. (C) 3-Methyladenine (3-MA) suppresses autophagy in <i>DBHD^−/−</i> fat body. (D) Foraging assay by feeding larvae with colored food (the baker’s yeast powder mixed with black ink). Green: GFP (A–C); Blue: DAPI (C).</p

Generating a <i>DBHD</i> null allele.

<p>(A) The <i>DBHD</i> genomic locus and the targeting strategy. P1–P4 represent the PCR primers. (B) PCR analysis of the genomic DNA. In <i>DBHD^−/−</i> larvae (−/−), a 4.8 kb fragment and a 5 kb fragment could be amplified by the corresponding primer pairs. (C) rtPCR analysis of the <i>DBHD</i> transcripts in various tissues. LB: larval brain; disc: mixtures of larval imaginal discs. α-tubulin (at 84B) was used as the positive control. (D) A DBHD antibody recognizes a band at about 55 kDa (arrow) of the whole larval extracts, which is absent in the <i>DBHD^−/−</i> larvae. <i>w¹¹¹⁸</i> was used as the wild-type control (WT). (E) Statistical analysis of the developmental profiles of two strains. The +/TM3 flies contains a healthy 3rd chromosome and a GFP-marked third chromosome balancer (<i>TM3, Kr::GFP</i>). The −/TM3 flies contains the same balancer and the <i>DBHD⁻</i> allele. Animals survived to different stages were counted. Numbers in the parenthesis are the theoretical values according to the Mendel rules. *: all the survived adults are heterozygotes. (F) Comparison of <i>DBHD^−/−</i> (−/−) and the sibling heterozygotes (−/+) at different days after egg laying. Embryos collected within three hours and cultured in the same food vials were picked for images at each time point. All heterozygotes have eclosed by 14 days after egg laying and thus were not pictured.</p

Clonal analyses of <i>DBHD^−/−</i> cells in the larval imaginal discs.

<p>(A–C) GFP signals. (C’) PH3. Random clones were generated in the wing (a) and eye (b) imaginal discs. <i>eyeless-flipase</i> induced large clones in the eye disc (C, C’). The <i>DBHD^−/−</i> cells are absent of GFP (green) and circled with solid lines. The wild-type twin spot cells are marked with double GFP signals and enclosed with dashed lines. Note the <i>DBHD^−/−</i> and the twin spots are similar in clone size. The amount of PH3-positive cells is not clearly declined or increased in the <i>DBHD⁻</i> clones.</p

The developmental profiles of flies cultured on various yeast foods.

<p>Note: The developmental profiles were displayed by listing the last stages that they survived and the time point when they started to enter (days after hatching). Pure yeast paste had the best rescue effects. Diluted food means the food nutrients (sugar, corn flour and baker’s yeast) were 50% of the normal food recipe. Yeast-free food has normal food recipe without yeast. In all test, we picked the newly hatched larvae at the same time point. No more than twenty larvae were cultured within each food chamber. At least 100 larvae in total were counted for each experiment.</p