Caste formation in the polyembryonic wasp Copidosoma floridanum (Hymenoptera: Encyrtidae): in vivo and in vitro analysis

The polyembryonic wasp Copidosoma floridanum produces two morphologically distinct types of larvae in its host Trichoplusia ni. Reproductive larvae consume the host, pupate, and form adult wasps, whereas precocious larvae manipulate the sex ratios of the reproductive caste and defend the brood against interspecific competitors. The previous study indicated that morphogenesis of the reproductive caste was associated with a 9-day competency period, and that ecdysteroids of host origin were required for completion of embryogenesis. Here we investigated whether factors associated with the host environment mediate morphogenesis of precocious larvae and caste determination. Embryogenesis of precocious larvae was found to be synchronized with specific stages of the host first-fourth instars. However, development of precocious larvae did not depend on environmental factors specifically associated with these host stages. Elevation of the host juvenoid titer using the analogue methoprene induced T. ni to undergo a supernumerary sixth instar, but did not alter the proportion of wasp embryos that developed into precocious and reproductive larvae. In contrast, embryos competent to initiate morphogenesis developed into precocious larvae when transplanted into novel host stages such as pupae. Development of precocious larvae was arrested by ablation of the host's source of ecdysteroids, but could be rescued dose-dependently by injection of 20-hydroxyecdysone. In vitro rearing studies confirmed that completion of embryogenesis of the precocious caste required an exogenous pulse of 20-hydroxyecdysone. Combined with previous studies, our results indicate that embryos forming precocious and reproductive larvae acquire the competence to undergo morphogenesis at different times. However, we find no evidence to suggest that caste determination is mediated by environmental factors associated with a specific stage of the host.     

P2Y2 receptor promotes intestinal microtubule stabilization and mucosal re‐epithelization in experimental colitis

P2Y₂ receptor expression is increased in intestinal epithelial cells (IECs) during inflammatory bowel diseases (IBDs). In this context, P2Y₂ stimulates PGE₂ release by IECs, suggesting a role in wound healing. For this study, we have used the non‐cancerous IEC‐6 cell line. IEC‐6 cell migration was determined using Boyden chambers and the single‐edged razor blade model of wounding. The receptor was activated using ATP, UTP, or 2‐thioUTP. Pharmacological inhibitors, a blocking peptide, a neutralizing antibody and interfering RNAs were used to characterize the signaling events. Focal adhesions and microtubule (MT) dynamics were determined by immunofluorescence using anti‐vinculin and anti‐acetylated‐α‐tubulin antibodies, respectively. In vivo, the dextran sodium sulfate mouse model of colitis was used to characterize the effects of P2Y₂ agonist 2‐thioUTP on remission. We showed that P2Y₂ increased cell migration and wound closure by recruiting Go protein with the cooperation of integrin α_v. Following P2Y₂ activation, we demonstrated that GSK3β activity was inhibited in response to Akt activation. This leads to MT stabilization and increased number of focal adhesions. In vivo, P2Y₂ activation stimulates remission, as illustrated by a reduction in the disease activity index values and histological scores as compared to control mice. These findings highlight a novel function for this receptor in IECs. They also illustrate that P2Y receptors could be targeted for the development of innovative therapies for the treatment of IBDs. J. Cell. Physiol. 228: 99–109, 2013. © 2012 Wiley Periodicals, Inc.     

Vasa expression and germ-cell specification in the spider mite <Emphasis Type="Italic">Tetranychus urticae</Emphasis>

The specification of germ cells is an important process during the development of all animals. Expression of an evolutionarily conserved gene such as vasa can be used as a marker for germ cell fate. We have isolated a vasa-related gene from the two-spotted spider mite (Tetranychus urticae) and used it to examine the segregation of germ cells in this animal. In spider mites, vasa expression first appears in a group of cells that do not join the initial blastoderm surface. Instead, these cells remain in the interior of the blastoderm and then migrate to posterior regions of the embryo, where they form a cluster that appears in regions of the embryo consistent with the gonads. The expression pattern of this spider mite vasa homologue implies a novel process acts to specify germ cells in this species and that the specification of germ cells is an evolutionarily labile process.     

Rapid specialization of counter defenses enables two-spotted spider mite to adapt to novel plant hosts

Genetic adaptation, occurring over a long evolutionary time, enables host-specialized herbivores to develop novel resistance traits and to efficiently counteract the defenses of a narrow range of host plants. In contrast, physiological acclimation, leading to the suppression and/or detoxification of host defenses, is hypothesized to enable broad generalists to shift between plant hosts. However, the host adaptation mechanisms used by generalists composed of host-adapted populations are not known. Two-spotted spider mite (TSSM; Tetranychus urticae) is an extreme generalist herbivore whose individual populations perform well only on a subset of potential hosts. We combined experimental evolution, Arabidopsis thaliana genetics, mite reverse genetics, and pharmacological approaches to examine mite host adaptation upon the shift of a bean (Phaseolus vulgaris)-adapted population to Arabidopsis. We showed that cytochrome P450 monooxygenases are required for mite adaptation to Arabidopsis. We identified activities of two tiers of P450s: general xenobiotic-responsive P450s that have a limited contribution to mite adaptation to Arabidopsis and adaptation-associated P450s that efficiently counteract Arabidopsis defenses. In approximately 25 generations of mite selection on Arabidopsis plants, mites evolved highly efficient detoxification-based adaptation, characteristic of specialist herbivores. This demonstrates that specialization to plant resistance traits can occur within the ecological timescale, enabling the TSSM to shift to novel plant hosts.

Mites can evolve highly efficient detoxification-based adaptation in approximately 25 generations on an initially unfavorable plant host, revealing that specialization can occur within the ecological timescale.     

Beta-endorphin modulates human immune activity via non-opiate receptor mechanisms

Here we report that Beta-endorphin is a potent and efficacious suppressor of phytohemagglutinin induced T-lymphocyte blastogenesis when human leukocytes are exposed early in the course of mitogenic activation. This suppression becomes more difficult to observe, however, if blastogenesis is established by prior exposure to mitogen. Suppression by Beta-endorphin is not blocked by pretreatment with the opiate antagonist naloxone. These results, therefore, suggest that neuroendocrine modulation of human immune expression may be a peripheral physiological function of Beta-endorphin which is mediated by mechanisms distinct from traditional opiate receptors.     

Aryl 1,4-diazepane compounds as potent and selective CB2 agonists: optimization of drug-like properties and target independent parameters

A high throughput screening campaign identified aryl 1,4-diazepane compounds as potent and selective cannabinoid receptor 2 agonists as compared to cannabinoid receptor 1. This class of compounds suffered from poor drug-like parameters as well as low microsomal stability and poor solubility. Structure-activity relationships are described with a focus on improving the drug-like parameters resulting in compounds with improved solubility and permeability.     

Spatial expression pattern of SAG12:GUS transgene in tobacco (Nicotiana tabacum)

Senescence syndrome is characterized by the breakdown of nutrients in senescing organs and their remobilization to the other parts of the plant. While proteases, nucleases, and proteins involved in nitrogen and lipid metabolism have been identified as cDNAs showing senescence-specific or senescence-preferred expression in many plant species, little is known about their spatial expression pattern that leads to the co-ordinated senescence of the whole organ. In order to elucidate the spatial regulation of SAGs, we have examined the expression pattern of SAG12:GUS in transgenic tobacco plants ( Nicotiana tabacum cv. Wisconsin 38). The SAG12 promoter was ubiquitously active in senescing leaves, however, specific SAG12 expression domains were found in senescing flowers.