Effect of Modified Cellulose Nanocrystals on the Structure of Calcium Silicate Hydrate Studied by Molecular Dynamics Simulation and Experiment.

The interfacial bonding of the four cellulose nanocrystals (CNCs) and calcium silicate hydrate (C-S-H) in vacuum and solution conditions was analyzed by molecular dynamics simulation. The binding energies were calculated, and the sources of interface strength were analyzed by the formation and lifetime of hydrogen bonds. The adsorption between CNC/C-S-H was characterized by the movement of interfacial atoms and CNC's adsorption conformation. The types of the functional group determine the bonding of the CNC/C-S-H, and the interface adsorption in two simulation conditions both followed: CNC-C (carboxyl) > CNC-O (hydroxyl) > CNC-N (amino) > CNC-S (sulfonic). The bonding of the interface affects the load transferred between the matrix and CNC, which can be reflected in the overall mechanical properties of the mortar. The mechanical strength of the mortar is in line with the simulation results. CNC-C has the strongest reinforcement effect, while CNC-S has the weakness effect. In the solution simulation, there is almost no chemical adsorption between C-S-H and CNC-S; instead, CNC-S decreased the bonding between the matrix and reduced the strength of the sample. Scanning electron microscopy found that CNC was interspersed in the matrix, riveting the matrix and enhanced the stability of the mortar structure. The influence of CNC on the mortar structure was analyzed by the calcium to silicon ratio (C/S) and it was showed that CNC-C, CNC-O, and CNC-N have an enhancement effect, while CNC-S decreased the coherence of the cement matrix. Durability and nuclear magnetic resonance tests further verified the effect of the four CNCs on the structure of mortar, and results indicated that CNC-C, CNC-O, and CNC-N can control the growth of hydration crystals, fill the cracks, and reduced porosity of samples, while CNC-S reduces the compactness of hydration products and ultimately decreased the mechanical and durability properties of the mortar.

Properties of Light Cementitious Composite Materials with Waste Wood Chips.

The CO2 emissions from the cement industry and the production of waste wood chips are increasing with the rapid growth of the construction industry. In order to develop a green environmental protection building material with low thermal conductivity and up to standard mechanical properties, in this study, pine waste wood chips were mixed into cement-based materials as fine aggregate, and three different kinds of cementitious binders were used, including sulfur aluminate cement (SAC), ordinary Portland cement (OPC), and granulated blast furnace slag (GBFS), to prepare a recycled light cementitious composite material. The mechanical, thermal conductivity, shrinkage, water absorption, and pore structure of a wood chip light cementitious composite material were studied by changing the Ch/B (the mass ratio of wood chip to binder). The results showed that the strength, dry density, and thermal conductivity of the specimens decreased significantly with the increase in the Ch/B, while the shrinkage, water absorption, and pore size increased with the increase in the Ch/B. By comparing three different kinds of cementitious binders, the dry density of the material prepared with OPC was 942 kg/m3, the compressive strength of the material prepared with SAC was 13.5 MPa, and the thermal conductivity of the material prepared with slag was the lowest at 0.15 W/m/K. From the perspective of low-cost and low-carbon emissions, it was determined that the best way to prepare a light cementitious composite with waste wood chips is to use granulated blast furnace slag (GBFS) as the cementitious binder.

A long-term demasculinization of X-linked intergenic noncoding RNAs in Drosophila melanogaster.

Recent studies have revealed key roles of noncoding RNAs in sex-related pathways, but little is known about the evolutionary forces acting on these noncoding RNAs. Profiling the transcriptome of Drosophila melanogaster with whole-genome tiling arrays found that 15% of male-biased transcribed fragments are intergenic noncoding RNAs (incRNAs), suggesting a potentially important role for incRNAs in sex-related biological processes. Statistical analysis revealed a paucity of male-biased incRNAs and coding genes on the X chromosome, suggesting that similar evolutionary forces could be affecting the genomic organization of both coding and noncoding genes. Expression profiling across germline and somatic tissues further suggested that both male meiotic sex chromosome inactivation (MSCI) and sexual antagonism could contribute to the chromosomal distribution of male-biased incRNAs. Comparative sequence analysis showed that the evolutionary age of male-biased incRNAs is a significant predictor of their chromosomal locations. In addition to identifying abundant sex-biased incRNAs in the fly genome, our work unveils a global picture of the complex interplay between noncoding RNAs and sexual chromosome evolution.

The Drosophila ortholog of breast cancer metastasis suppressor gene, dBrms1, is critical for developmental timing through regulating ecdysone signaling.

BRMS1 was first discovered as a human breast carcinoma metastasis suppressor gene. However, the mechanism of BRMS1 in tumor metastasis and its developmental role remain unclear. In this paper, we first report the identification of the Drosophila ortholog of human BRMS1, dBrms1. Through a genetic approach, the role of dBrms1 during development has been investigated. We found that dBrms1 is an essential gene and loss of dBrms1 function results in lethality at early developmental stages. dBrms1mutants displayed phenotypes such as developmental delay and failure to initiate metamorphosis. Further analysis suggests that these phenotypes are contributed by defective ecdysone signaling and expression of target genes of the ecdysone pathway. Therefore, dBrms1 is required for growth control by acting as a modulator of ecdysone signaling in Drosophila and is required for metamorphosis for normal development.

mir-35 is involved in intestine cell G1/S transition and germ cell proliferation in C. elegans.

MicroRNA (miRNA) regulates gene expression in many cellular events, yet functions of only a few miRNAs are known in C. elegans. We analyzed the function of mir-35-41 unique to the worm, and show here that mir-35 regulates the G1/S transition of intestinal cells and germ cell proliferation. Loss of mir-35 leads to a decrease of nuclei numbers in intestine and distal mitotic gonad, while re-introduction of mir-35 rescues the mutant phenotypes. Genetic analysis indicates that mir-35 may act through Rb/E2F and SCF pathways. Further bioinformatic and functional analyses demonstrate that mir-35 targets evolutionally conserved lin-23 and gld-1. Together, our study reveals a novel function of mir-35 family in cell division regulation.

Ce-wts-1 plays important roles in Caenorhabditis elegans development.

The Hippo-Warts pathway defines a novel signaling cascade involved in organ size control and tumor suppression. However, the developmental function of this pathway is less understood. Here we report that the Caenorhabditis elegans homolog of Warts, Ce-wts-1, plays important roles during worm development. The null allele of Ce-wts-1 causes L1 lethality. Partial loss of Ce-wts-1 function by RNAi reveals that Ce-wts-1 is involved in many developmental processes such as larval development, growth rate regulation, gut granule formation, pharynx development, dauer formation, lifespan and body length control. Genetic analyses show that Ce-wts-1 functions synergistically with the TGF-beta Sma/Mab pathway to regulate body length. In addition, CE-WTS-1::GFP is enriched near the inner cell membrane, implying its possible membrane-related function.

The function of a spindle checkpoint gene bub-1 in C. elegans development.

BACKGROUND: The serine/threonine kinase BUB1 (Budding Uninhibited by Benzimidazole 1) was originally identified in yeast as a checkpoint protein, based on its mutant's incapacity of delaying the cell cycle in response to loss of microtubules. Our understanding of its function is primarily from studies carried out in yeast S. cerevisiae. It has been shown that it is a component of the mitotic spindle checkpoint and regulates the separation of sister chromatids through its downstream molecules. However, its roles in multi-cellular organisms remain unclear. METHODS AND FINDINGS: In nematode C. elegans, rapid cell divisions primarily occur in embryos and in germline of postembryonic larvae and adults. In addition, a select set of cells undergo a few rounds of cell division postembryonically. One common phenotype associated with impaired cell division is described as Stu (Sterile and Uncoordinated) [1], [2]. We conducted a genetic screen for zygotic mutants that displayed Stu phenotype in C. elegans. We isolated seven Stu mutants that fell into five complementation groups. We report here that two mutations, FanWang5 (fw5) and FanWang8 (fw8) affect the bub-1 gene, a homolog of yeast BUB1. Both mutant alleles of fw5 and fw8 exhibited variable behavioral defects, including developmental arrest, uncoordination and sterility. The number of postembryonically born neurons in the ventral cord decreased and their axon morphology was abnormal. Also, the decrease of neurons in the ventral cord phenotype could not be suppressed by a caspase-3 loss-of-function mutant. In addition, bub-1(fw5 and fw8) mutants showed widespread effects on postembryonic development in many cell lineages. We found that bub-1 functioned maternally in several developmental lineages at the embryonic stage in C. elegans. Studies in yeast have shown that BUB1 functions as a spindle checkpoint protein by regulating the anaphase promoting complex/cyclosome (APC/C). We performed double mutant analysis and observed that bub-1 genetically interacted with several downstream genes, including fzy-1/CDC20, mat-2/APC1 and emb-27/APC6. CONCLUSIONS: Our results demonstrate a conserved role of bub-1 in cell-cycle regulation and reveal that C. elegans bub-1 is required both maternally and zygotically. Further, our genetic analysis is consistent with that the function of bub-1 in C. elegans is likely similar to its yeast and mammalian homologs.

Detection of intergenic non-coding RNAs expressed in the main developmental stages in Drosophila melanogaster.

How many intergenically encoded non-coding RNAs (ncRNAs) are expressed during various developmental stages in Drosophila? Previous analyses in one or a few developmental stages indicated abundant expression of intergenic ncRNAs. However, some reported that ncRNAs have been recently falsified, and, in general, the false positive rate for ncRNA detection is unknown. In this report, we used reverse transcription-PCR (RT-PCR), a more robust method, to detect ncRNAs from the intergenic regions that are expressed in four major developmental stages (6-8 h embryo, 20-22 h embryo, larvae and adult). We tested 1027 regions, approximately 10% of all intergenic regions, and detected transcription by RT-PCR. The results from 18 342 RT-PCR experiments revealed evidence for transcription in 72.7% of intergenic regions in the developmental process. The early developmental stage appears to be associated with more abundant ncRNAs than later developmental stages. In the early stage, we detected 43.6% of intergenic regions that encode transcripts in the triplicate RT-PCR experiments, yielding an estimate of 5006 intergenic regions in the entire genome likely encoding ncRNAs. We compared the RT-PCR-related approach with previous tiling array-based approach and observed that the latter method is insensitive to short ncRNAs, especially the molecules less than 120 bp. We measured false positive rates for the analyzed genomic approaches including the RT-PCR and tiling array method.

Both upstream and downstream intergenic regions are critical for the mob as tumor suppressor gene activity in Drosophila.

The Drosophila mats gene plays a critical role in growth control. Using molecular genetic approaches we investigated how mats is regulated in development. A 2236-bp genomic sequence that contains entire mats including upstream and downstream intergenic regions can rescue mats mutant phenotypes, indicating that regulatory elements necessary for proper mats expression are mostly retained. However, constructs without the upstream or downstream intergenic region failed to rescue mats mutants, demonstrating the functional importance of these sequences. Moreover, mats expression is reduced in mats(e17), a mats allele with over one-third of the downstream intergenic region deleted. Consistent with a model that the downstream intergenic region is critical for mats activity, this sequence contains evolutionarily conserved elements and has enhancer activities.

Minichromosome maintenance protein 5 homologue in Caenorhabditis elegans plays essential role for postembryonic development.

Genome duplication is tightly controlled in multicellular organisms to ensure the genome stability. Studies in Saccharomyces cerevisiae and Xenopus show that minichromosome maintenance (MCM) proteins are essential for genome duplication. However, the development role of MCM proteins in multicellular organisms is not well known. MCM5 encodes a member of the MCM2-7 protein family involved in the initiation of DNA replication. The sequences of all Mcm5 homologues from yeast to human are highly conserved and suggest that their functions are also conserved. Here, we isolated the first mutant allele of mcm-5 (fw7) in Caenorhabditis elegans. Homozygous mcm-5 (fw7) mutants from heterozygous parents exhibited variable larval lethality and adult sterility. The postembryonically born neuron number was decreased and also showed aberrant axon morphology. Our study revealed that the losses of neurons in mcm-5 (fw7) mutants were caused by cell cycle defects not by programmed cell death. The examination showed that mcm-5 was widely used for postembryonic development in multiple cells such as seam cells, gonad and intestinal cells. Knockdown of mcm-5 by RNAi caused 98.1% embryonic arrest, suggesting that mcm-5 was also required for embryonic development. After RNAi treatment of the other MCM2-7 family members, we found that they all exhibited similar phenotypes as mcm-5, suggesting that the MCM2-7 family in C. elegans might function associated with cell division as its homologues in S. cerevisiae.

Vertebrate MAX-1 is required for vascular patterning in zebrafish.

During embryogenesis, stereotypic vascular patterning requires guidance cues from neighboring tissues. However, key molecules involved in this process still remain largely elusive. Here, we report molecular cloning, expression, and functional studies of zebrafish max-1, a homolog of Caenorhabditis elegans max-1 that has been implicated in motor neuron axon guidance. During early embryonic development, zebrafish max-1 is specifically expressed in subsets of neuronal tissues, epithelial cells, and developing somites through which vascular endothelial cells migrate from large ventral axial vessels to form stereotypic intersegmental blood vessels (ISV). Blocking zebrafish max-1 mRNA splicing by morpholino injection led to aberrant ISV patterning, which could be rescued by injection of either C. elegans or zebrafish max-1 mRNA. Analysis of motor neurons in the same region showed normal neuronal axon pathfinding. Further studies suggested that the ISV defect caused by max-1 knockdown could be partially rescued by overexpression of ephrinb3 and that max-1 was involved in mediating membrane localization of ephrin proteins, which have been shown to provide guidance cues for endothelial cell migration. Our findings therefore suggest that max-1, acting upstream of the ephrin pathway, is critically required in vascular patterning in vertebrate species.

[Development of retrovirus-mediated insertional mutagenesis in zebrafish and its application in saturation mutagenesis and gene screening].

The strategies of large-scale mutagenesis and gene screening include chemical mutagenesis, insertional mutagenesis and gene trap. Insertional mutagenesis is a method for identifying genes by using the integration of DNA as the mutagen, thereby facilitating the cloning of the mutated gene. The use of retrovirus-mediated insertional mutagenesis in zebrafish has led to the mutation and rapid identification of hundreds of genes required for embryonic development and cell growth. Gene trap elements are also used in the construction of retrovirus vectors. The whole system is likely to make zebrafish the first vertebrate to achieve saturation mutagenesis and gene screening.