The genome of the Hi5 germ cell line from Trichoplusia ni, an agricultural pest and novel model for small RNA biology

We report a draft assembly of the genome of Hi5 cells from the lepidopteran insect pest, Trichoplusia ni, assigning 90.6% of bases to one of 28 chromosomes and predicting 14,037 protein-coding genes. Chemoreception and detoxification gene families reveal T. ni-specific gene expansions that may explain its widespread distribution and rapid adaptation to insecticides. Transcriptome and small RNA data from thorax, ovary, testis, and the germline-derived Hi5 cell line show distinct expression profiles for 295 microRNA- and \u3e 393 piRNA-producing loci, as well as 39 genes encoding small RNA pathway proteins. Nearly all of the W chromosome is devoted to piRNA production, and T. ni siRNAs are not 2 -O-methylated. To enable use of Hi5 cells as a model system, we have established genome editing and single-cell cloning protocols. The T. ni genome provides insights into pest control and allows Hi5 cells to become a new tool for studying small RNAs ex vivo

Trunk muscle activity during the simultaneous performance of two voluntary tasks: A trunk task and a pulsed expiration task

Trunk control is intriguing because trunk muscles must meet multiple requirements during the performance of everyday tasks (e.g., balancing, locomotion, musical instrument playing, reaching, trunk bending, vocalizing). A unique feature of trunk muscles is that they often participate in simultaneous trunk movement and breathing-related behaviors. This study was designed to test the hypothesis that two voluntary task-specific muscle activity patterns could combine linearly when both tasks activate the same muscles. Surface electromyograms (EMG) were recorded from four trunk sites (upper and lower lateral abdominal, medial and lateral back) during the performance of a trunk task, pulsed expiration task, and combined task (hunk + pulsed expiration task). The trunk task varied across four experiments, and included a static holding task or a uni-directional movement task in both flexion and extension directions. The expiration task was constant. Selected task variables (lung volume, movement amplitude and duration, expiratory target pressure) were consistent across all tasks. For each EMG site, a linear prediction (predicted EMG trace) was calculated from the mathematical addition of the task-specific EMG recorded during the individual trunk and expiration tasks. This linear prediction was compared to the actual muscle activity recorded during the combined task (measured EMG trace) and a point-to-point correlation was performed on the two traces to determine how closely they matched. Findings showed that in just over half the comparisons, the combined muscle activity pattern (measured EMG trace) was the same as a linear addition of each individual muscle activity pattern (predicted EMG trace). Such linear addition implies that two sets of descending command signals reach motoneuron pools essentially unmodified, and that motoneurons supplying trunk muscles may be specially organized to receive dual and simultaneous voluntary neural drive. In the remaining comparisons, the EMG activity for the two individual tasks, were superimposed, but not linearly. This finding suggests that although individual muscles are activated as a unit, selected muscles may be modified by sensory feedback. This flexibility allows the nervous system to take advantage of a muscles mechanical effectiveness and to adapt to environmental constraints without having to reconfigure or construct a new set of instructions

The Drosophila RNA methyltransferase, DmHen1, modifies germline piRNAs and single-stranded siRNAs in RISC

Small silencing RNAs repress gene expression by a set of related mechanisms collectively called RNA-silencing pathways [1, 2]. In the RNA interference (RNAi) pathway [3], small interfering mRNA (siRNAs) defend cells from invasion by foreign nucleic acids, such as those produced by viruses. In contrast, microRNAs (miRNAs) sculpt endogenous mRNA expression [4]. A third class of small RNAs, Piwi-interacting RNAs (piRNAs), defends the genome from transposons [5-9]. Here, we report that Drosophila piRNAs contain a 2\u27-O-methyl group on their 3\u27 termini; this is a modification previously reported for plant miRNAs and siRNAs [10] and mouse and rat piRNAs [11, 12, 13]. Plant small-RNA methylation is catalyzed by the protein HEN1 [10, 14, 15]. We find that DmHen1, the Drosophila homolog of HEN1, methylates the termini of siRNAs and piRNAs. Without DmHen1, the length and abundance of piRNAs are decreased, and piRNA function is perturbed. Unlike plant HEN1, DmHen1 acts on single strands, not duplexes, explaining how it can use as substrates both siRNAs-which derive from double-stranded precursors-and piRNAs-which do not [8, 13]. 2\u27-O-methylation of siRNAs may be the final step in assembly of the RNAi-enzyme complex, RISC, occurring after an Argonaute-bound siRNA duplex is converted to single-stranded RNA

The relationship between the marketing mix and share of category requirements

A criticism of purchase-based brand loyalty measures is that they are confounded by the marketing mix variables that affect brand choice. This paper investigates the magnitude and direction of the associations for share of category requirements (SCR), defined as each brand's share among the group of households who bought the brand at least once during the time period under consideration. We discuss the theoretical foundations for the relationships between SCR and a set of marketing mix variables (price, promotions, retail distribution) and conduct a latent structure regression analysis of brand-level data to test these relationships. We find that, although the relationship between the marketing mix variables and SCR is statistically significant, in real terms the magnitude of the association is fairly low.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47199/1/11002_2004_Article_BF00557307.pd