Identification of Root-knot Nematodes (Meloidogyne spp.) of Arkansas using Molecular Diagnostics

Root-knot nematodes (Meloidogyne spp.) are highly-adaptable, obligate plant parasites distributed worldwide. In addition, root-knot nematodes are an economically important genus of plant-parasitic nematodes. Meloidogyne incognita, M. arenaria, M. javanica, M. hapla and M. graminis have been reported from Arkansas during 1964 to 1994. Previous identifications were based primarily on morphological characters and host differentials. In this study, identification using molecular diagnostics methods was performed to identify Meloidogyne species present in Arkansas. A total of 106 soil and root samples from 36 of the 75 counties were collected and processed to obtain root-knot nematodes. Polymerase chain reaction (PCR) was performed to amplify a region between cytochrome oxidase II and 16s ribosomal mitochondrial DNA (mtDNA) genes of root-knot nematodes. Of the species identified in the present survey, M. incognita was the most abundant followed by a few isolated samples of M. marylandi, M. haplanaria, M. hapla, M. arenaria and M. partityla. As a result of the sequencing analysis, a new set of PCR primers that amplifies the same region of mtDNA was designed to identify M. incognita. Furthermore, a species specific PCR protocol was developed using mitochondrial marker for routine nematode identifications of the most common species, M. incognita. Additionally, cultures of different species identified were established and maintained in the greenhouse on a suitable host to facilitate future research. Since correct identification of species in the field is imperative for effective control of any pathogen, findings from this research will be useful in developing suitable crop management strategies in Arkansas

Virulence Phenotypes of Rotylenchulus reniformis: Evaluation of Host Status of Cotton and Utility of Single Nucleotide Polymorphisms (SNPs) for Identification

Comparative reproduction and pathogenicity of reniform nematode (Rotylenchulus reniformis) populations derived from single-egg masses and collected form West Carroll (WC), Rapides (RAP), Morehouse (MOR), and Tensas (TEN) parishes in Louisiana were evaluated in microplot and greenhouse trials. Data from microplot trials showed significant differences among isolates of reniform nematode in both reproduction and pathogenicity on upland cotton (Gossypium hirsutum) cultivars Phytogen 499 WRF, Deltapine 1133 B2RF, and Phytogen 333 WRF. Across all cotton cultivars, MOR and RAP isolates had the greatest and the least reproduction values of 331.8 and 230.2, respectively. Reduction in plant dry weight, number of bolls, seed cotton weight, and lint weight was the greatest and the least for MOR and RAP isolate, respectively. The reproduction and pathogenicity of WC and TEN isolates were intermediate. In the greenhouse experiment, reproduction of MOR and RAP isolates across all cotton genotypes (three cultivars used in microplot experiment, cultivar Stoneville 4946 GLB2, and two resistant germplasm lines MT2468 Ren3 and M713 Ren5) was the greatest (reproduction value 10.7) and the least (reproduction value 7.9), respectively. Although reproduction values of reniform nematode were lower in the germplasm lines than the cultivars, the germplasm lines sustained greater plant weight loss. The variability in reproduction and pathogenicity among endemic populations of reniform nematode in both the microplot and greenhouse experiments adds further support to the hypothesis that virulence phenotypes of R. reniformis exist. In order to determine genetic variability in reniform nematode populations, 31 KASP SNP primers sets were evaluated against 13 reniform nematode isolates that include MOR and RAP isolates from Louisiana as well as other 11 isolates from Mississippi, Arkansas, Hawaii, and Alabama. Twenty-six SNP assays amplified genomic DNA of reniform nematode isolates while five failed to successfully amplify. Five SNP assays identified genetic differences within and among populations of reniform nematode from Louisiana, Mississippi, and Arkansas. Similarly, eight SNP assays identified genetic differences among samples from Hawaii, and Alabama. The SNP markers developed in this study will be useful in resistance breeding programs as well as in the assessment of the genetic diversity, origin, and subsequent distribution of this nematode

Affective Computing for Human-Robot Interaction Research: Four Critical Lessons for the Hitchhiker

Social Robotics and Human-Robot Interaction (HRI) research relies on different Affective Computing (AC) solutions for sensing, perceiving and understanding human affective behaviour during interactions. This may include utilising off-the-shelf affect perception models that are pre-trained on popular affect recognition benchmarks and directly applied to situated interactions. However, the conditions in situated human-robot interactions differ significantly from the training data and settings of these models. Thus, there is a need to deepen our understanding of how AC solutions can be best leveraged, customised and applied for situated HRI. This paper, while critiquing the existing practices, presents four critical lessons to be noted by the hitchhiker when applying AC for HRI research. These lessons conclude that: (i) The six basic emotions categories are irrelevant in situated interactions, (ii) Affect recognition accuracy (%) improvements are unimportant, (iii) Affect recognition does not generalise across contexts, and (iv) Affect recognition alone is insufficient for adaptation and personalisation. By describing the background and the context for each lesson, and demonstrating how these lessons have been learnt, this paper aims to enable the hitchhiker to successfully and insightfully leverage AC solutions for advancing HRI research.Comment: 11 pages, 3 figures, 1 tabl

Spatio-Temporal Analysis of Facial Actions using Lifecycle-Aware Capsule Networks

Most state-of-the-art approaches for Facial Action Unit (AU) detection rely upon evaluating facial expressions from static frames, encoding a snapshot of heightened facial activity. In real-world interactions, however, facial expressions are usually more subtle and evolve in a temporal manner requiring AU detection models to learn spatial as well as temporal information. In this paper, we focus on both spatial and spatio-temporal features encoding the temporal evolution of facial AU activation. For this purpose, we propose the Action Unit Lifecycle-Aware Capsule Network (AULA-Caps) that performs AU detection using both frame and sequence-level features. While at the frame-level the capsule layers of AULA-Caps learn spatial feature primitives to determine AU activations, at the sequence-level, it learns temporal dependencies between contiguous frames by focusing on relevant spatio-temporal segments in the sequence. The learnt feature capsules are routed together such that the model learns to selectively focus more on spatial or spatio-temporal information depending upon the AU lifecycle. The proposed model is evaluated on the commonly used BP4D and GFT benchmark datasets obtaining state-of-the-art results on both the datasets.Comment: Updated Figure 6 and the Acknowledgements. Corrected typos. 11 pages, 6 figures, 3 table

Properties of the nicotinic acid adenine dinucleotide phosphate-binding protein in sea urchin eggs.

Nicotinic acid adenine dinucleotide phosphate (NAADP) has recently emerged as a novel intracellular calcium mobilising messenger in a variety of cells. Whilst increasing evidence suggests that NAADP acts on a distinct binding protein, little is known regarding the biochemical properties of the putative NAADP "receptor". My thesis investigates properties of the NAADP-binding protein in sea urchin eggs. Firstly, I show that NAADP binding to its target protein is inhibited by altering the protein:lipid ratio of soluble sea urchin egg homogenates - an effect prevented and reversed specifically by addition of exogenous phospholipids. These data highlight the importance of the lipid environment in maintenance of NAADP binding to its target protein. In addition, I show that upon binding its ligand, the NAADP-binding protein undergoes an unusual stabilization process that is dependent upon the time the receptor is exposed to its ligand. This property endows the NAADP-binding protein with the extraordinary ability to detect the duration of its activation. Finally I describe the development of a highly sensitive radioreceptor assay (based upon the sea urchin egg NAADP-binding protein) that is capable of detecting low levels of NAADP from cellular extracts. I apply this technique to determine NAADP levels in a variety of extracts prepared from cells under resting and stimulated conditions