Global network structure of dominance hierarchy of ant workers

Dominance hierarchy among animals is widespread in various species and believed to serve to regulate resource allocation within an animal group. Unlike small groups, however, detection and quantification of linear hierarchy in large groups of animals are a difficult task. Here, we analyse aggression-based dominance hierarchies formed by worker ants in Diacamma sp. as large directed networks. We show that the observed dominance networks are perfect or approximate directed acyclic graphs, which are consistent with perfect linear hierarchy. The observed networks are also sparse and random but significantly different from networks generated through thinning of the perfect linear tournament (i.e., all individuals are linearly ranked and dominance relationship exists between every pair of individuals). These results pertain to global structure of the networks, which contrasts with the previous studies inspecting frequencies of different types of triads. In addition, the distribution of the out-degree (i.e., number of workers that the focal worker attacks), not in-degree (i.e., number of workers that attack the focal worker), of each observed network is right-skewed. Those having excessively large out-degrees are located near the top, but not the top, of the hierarchy. We also discuss evolutionary implications of the discovered properties of dominance networks.Comment: 5 figures, 2 tables, 4 supplementary figures, 2 supplementary table

Detection of negative strand RNA of hepatitis C virus in infected liver and serum.

The negative strand RNA of hepatitis C virus, supposed to be a replicative intermediate of the virus appears to indicate viral replication. In this study, we detected the negative strand RNA by using reverse transcription-polymerase chain reaction with RNase A digestion to degrade the remaining positive strand genomic sequence of the virus after complementary DNA (cDNA) synthesis. In vitro transcribed positive-stranded mutant RNA was not detected by this method. Sample sera and liver tissues of 16 patients with chronic hepatitis C virus infection (liver fibrosis, 1; chronic hepatitis, 13; liver cirrhosis, 2) were analysed for negative strand RNA of hepatitis C virus. The negative strand RNA sequence was detected in 15 (93%) of 16 liver tissues and in 11 (78%) of 14 sera. The study demonstrated that negative strand RNA of hepatitis C virus in serum and liver tissue could be specifically detected.</p

Event-based Camera Simulation using Monte Carlo Path Tracing with Adaptive Denoising

This paper presents an algorithm to obtain an event-based video from noisy frames given by physics-based Monte Carlo path tracing over a synthetic 3D scene. Given the nature of dynamic vision sensor (DVS), rendering event-based video can be viewed as a process of detecting the changes from noisy brightness values. We extend a denoising method based on a weighted local regression (WLR) to detect the brightness changes rather than applying denoising to every pixel. Specifically, we derive a threshold to determine the likelihood of event occurrence and reduce the number of times to perform the regression. Our method is robust to noisy video frames obtained from a few path-traced samples. Despite its efficiency, our method performs comparably to or even better than an approach that exhaustively denoises every frame.Comment: 8 pages, 6 figures, 3 table

Hd3a Florigen Recruits Different Proteins to Reveal Its Function in Plant Growth and Development

The nature of Hd3a protein in rice and its ortholog FT in Arabidopsis as a florigen has been proposed. However, molecular mechanism of its function still remains to be investigated. Therefore, it is important to search their interaction partners to better understand their signaling in flowering. As a long-distance signal that moves along leaf cells and the vascular system of leaves and stem and exerts its action in apical buds, it is important to determine the possible mediators of such common responses activated by Hd3a. To search Hd3a interactor, yeast two-hybrid screening have performed by using a cDNA library. A wide range of Hd3a interacting proteins involved in signaling were identified, including GF14c, OsKANADI and the BRI1 kinase domain interacting protein 116b (BIP116b). To reveal its function, Hd3a recruits different protein in plant developmental stage. It is possible that Hd3a and its partner(s) may form a platform for cross-talk between signal transduction pathways. Another homolog of Hd3a in many plants was identified and sugessted that Hd3a/FT has versatile role in plant development. This role depend on its partner and interaction to achieve its function. Our understanding in floral transition in rice would make for better crop management in future

Functional Analysis of OsKANADI1, A Florigen Hd3a Interacting Protein in Rice (Oryza sativa L.)

OsKANADI1 is considered as a florigen Hd3a interacting protein. To study the function of OsKANADI1, the expression pattern of OsKANADI1 was performed by semiquantitative RT-PCR with various wild-type tissues in the floral transition stage. The results demonstrated that OsKANADI1 was expressed in all organs of wild-type plants, but was highest in roots and leaves. We hypothesize that OsKANADI1 is a transcription factor in rice because it contains a GARP domain and posses a nuclear localization signal. To determine whether OsKANADI1 encodes a nuclear protein, full-length OsKANADI1 fused to GFP was introduced into onion epidermis cells by particle bombardment. The result revealed that OsKANADI1 was localized in the nucleus, suggesting that OsKANADI1 may be a transcription factor. Functional analysis was carried out using a reverse genetics approach to generate gain of function mutant (overexpression) and knockdown mutant (RNAi). The results showed that suppression of OsKANADI1 by RNAi displayed branching and increasing tiller number in several lines. This phenotype resembles to the Hd3a overexpressed plants indicating they possibly function in similar pathway.Key words : OsKANADI1, Transcription factor, Hd3a interacting protein, Ric

A new application of the SFDA-staining method to assessment of the freezing tolerance in leaves of alpine plants

For the first time, this study used 5- (6-) sulfofluorescein diacetate (SFDA), a fluorescent product in plant cells converted by esterase activity to fluorescein-5- (and 6-) sulfonic acid (FSA), to assess the freezing tolerance of leaf cells. We were able to readily distinguish living and dead cells, and detect differences in freezing tolerance among five alpine plants using the SFDA-staining method. We also compared this method with two conventional methods, the electrolyte leakage test and fluorescein diacetate (FDA) staining method. The electrolyte leakage test often over- or underestimated freezing injury. With the uninjured control samples, the FDA-staining method failed to stain all leaf cells, while the SFDA-staining method stained almost 100%. From these results, we concluded that SFDA-staining is a more convenient, accurate and reproducible method for analyses of freezing tolerance