Secretory RING finger proteins function as effectors in a grapevine galling insect.

BackgroundAll eukaryotes share a conserved network of processes regulated by the proteasome and fundamental to growth, development, or perception of the environment, leading to complex but often predictable responses to stress. As a specialized component of the ubiquitin-proteasome system (UPS), the RING finger domain mediates protein-protein interactions and displays considerable versatility in regulating many physiological processes in plants. Many pathogenic organisms co-opt the UPS through RING-type E3 ligases, but little is known about how insects modify these integral networks to generate novel plant phenotypes.ResultsUsing a combination of transcriptome sequencing and genome annotation of a grapevine galling species, Daktulosphaira vitifoliae, we identified 138 putatively secretory protein RING-type (SPRINGs) E3 ligases that showed structure and evolutionary signatures of genes under rapid evolution. Moreover, the majority of the SPRINGs were more expressed in the feeding stage than the non-feeding egg stage, in contrast to the non-secretory RING genes. Phylogenetic analyses indicated that the SPRINGs formed clusters, likely resulting from species-specific gene duplication and conforming to features of arthropod host-manipulating (effector) genes. To test the hypothesis that these SPRINGs evolved to manipulate cellular processes within the plant host, we examined SPRING interactions with grapevine proteins using the yeast two-hybrid assay. An insect SPRING interacted with two plant proteins, a cellulose synthase, CSLD5, and a ribosomal protein, RPS4B suggesting secretion reprograms host immune signaling, cell division, and stress response in favor of the insect. Plant UPS gene expression during gall development linked numerous processes to novel organogenesis.ConclusionsTaken together, D. vitifoliae SPRINGs represent a novel gene expansion that evolved to interact with Vitis hosts. Thus, a pattern is emerging for gall forming insects to manipulate plant development through UPS targeting

Space Suit Radiator Performance in Lunar and Mars Environments

During an ExtraVehicular Activity (EVA), both the heat generated by the astronaut's metabolism and that produced by the Portable Life Support System (PLSS) must be rejected to space. The heat sources include the heat of adsorption of metabolic CO2, the heat of condensation of water, the heat removed from the body by the liquid cooling garment and the load from the electrical components. Although the sublimator hardware to reject this load weighs only 1.58 kg (3.48 lbm), an additional 3.6 kg (8 lbm) of water are loaded into the unit, most of which is sublimated and lost to thus become the single largest expendable during an eight hour EVA. We can significantly reduce the amount of expendable water consumed in the sublimator by using a radiator to reject heat from the Astronaut during an EVA. Last year we reported on the design and initial operational assessment tests of our novel radiator designated the Radiator And Freeze Tolerant heat eXchanger (RAFT-X). Herein, we report on tests conducted in the NASA Johnson Space Center Chamber E Thermal Vacuum Test Facility. Up to 260 W (900 Btu/h) of heat were rejected in Lunar and Mars environments with temperatures as cold as -170 C (- 275 F). Further, the RAFT-X endured several freeze / thaw cycles and in fact, the heat exchanger was completely frozen three times without any apparent damage to the unit

Photosynthetic Response of Soybean to Twospotted Spider Mite (Acari: Tetranychydae) Injury

The twospotted spider mite Tetranychus urticae Koch is a common pest on soybean plants. To clarify plantarthropod interaction on mite-soybean system, leaf fluorescence, photosynthetic responses to variable carbon dioxide levels, and chlorophyll content were evaluated. Significant photosynthetic rate reduction was observed due to stomatal limitation. Stomatal closure was the major plant physiological response. As a consequence, there was reduction in photosynthetic rates. Surprisingly, plants did not show chlorophyll content reduction associated with photosynthetic impairment. No differences in fluorescence data indicate that T. urticae injury did not impair the function of light harvesting and photoelectron transport. These results showed that T. urticae could be a serious pest of soybean even on lower infestation, at least when photosynthesis was determinant to yield

The Genome Sequence of the Grape Phylloxera Provides Insights into the Evolution, Adaptation, and Invasion Routes of an Iconic Pest

Background: Although native to North America, the invasion of the aphid-like grape phylloxera Daktulosphaira vitifoliae across the globe altered the course of grape cultivation. For the past 150 years, viticulture relied on grafting-resistant North American Vitis species as rootstocks, thereby limiting genetic stocks tolerant to other stressors such as pathogens and climate change. Limited understanding of the insect genetics resulted in successive outbreaks across the globe when rootstocks failed. Here we report the 294-Mb genome of D. vitifoliae as a basic tool to understand host plant manipulation, nutritional endosymbiosis, and enhance global viticulture. Results: Using a combination of genome, RNA, and population resequencing, we found grape phylloxera showed high duplication rates since its common ancestor with aphids, but similarity in most metabolic genes, despite lacking obligate nutritional symbioses and feeding from parenchyma. Similarly, no enrichment occurred in development genes in relation to viviparity. However, phylloxera evolved > 2700 unique genes that resemble putative effectors and are active during feeding. Population sequencing revealed the global invasion began from the upper Mississippi River in North America, spread to Europe and from there to the rest of the world. Conclusions: The grape phylloxera genome reveals genetic architecture relative to the evolution of nutritional endosymbiosis, viviparity, and herbivory. The extraordinary expansion in effector genes also suggests novel adaptations to plant feeding and how insects induce complex plant phenotypes, for instance galls. Finally, our understanding of the origin of this invasive species and its genome provide genetics resources to alleviate rootstock bottlenecks restricting the advancement of viticulture

Eco-physiological and molecular manipulation of leaf-level primary and secondary metabolism by arthropod herbivory

Arthropod herbivory fundamentally alters ecosystem function and challenges agricultural productivity because herbivores alter photosynthesis. Feeding removes tissues and resources for growth but often introduces unseen physiological costs mediated by a reallocation in resources from growth to defense or by alterations to primary and secondary metabolism. The type of feeding damage depends on the mouthparts of the herbivore and, in part, determines the magnitude and mechanism by which photosynthesis is altered. However, there is a lack of understanding of these effects across model systems to evaluate conserved mechanisms of plant responses to herbivory. Documenting these responses from the observed and manipulated eco-physiological level down to the level of the gene can provide mechanistic understanding of how photosynthesis changes under herbivory and, ultimately, what initiates the reallocation of resources from primary to secondary metabolism (i.e., plant defense). Understanding the connections between genotype and phenotype can enhance our knowledge of ecosystem function amidst a rapidly changing climate by elucidating resource-driven trade-offs, and, as a result, forms the basis for this dissertation. Plant responses to herbivory depend on the plant under attack and the attacking agent, but variability in the methods by which the interaction is observed makes it difficult to distinguish trends. As such, I synthesized the available literature in a review that elucidated four mechanisms for the alteration of photosynthesis at the leaf level. Arthropods sever vasculature, alter sink/source relationships, release autotoxic chemicals, or initiate a trade-off of resources from photosynthesis to defense in remaining leaf tissue. This review is presented in Chapter 2 and establishes the framework for the following chapters in which I investigate these mechanisms. Because Earth is experiencing rapid environmental change, I surveyed leaf-level response of model forest species to multiple damage types when grown under predicted climate change conditions in Chapter 3. Elevated CO2 attenuated damage for all damage types. As a result, the changing climate will, in part, attenuate the negative effects of herbivory on leaf-level photosynthesis. A common theme in this study and others is that damage to remaining leaf tissue from defoliation declines with time across species; however, contrary examples exist where inducible processes interact more with photosynthesis. Therefore I examined how inducible defense signaling and metabolite production altered photosynthesis in Chapter 4. I found that wound signaling immediately impaired electron transport, and defense synthesis correlated with sustained reductions in photosynthesis. Taken together, these data indicate a conserved mechanism underlying defense signaling modulates the trade-off from using resources for growth to defense. As the preceding chapters suggest, hidden physiological costs can reduce photosynthesis relative to the damage type. Insect parasites of plants may influence leaf and canopy-level processes through the manipulation of sink/source dynamics by an unknown mechanism. In Chapter 5 I reexamined the grape-phylloxera system to reveal that the gall-forming insect parasite phylloxera induces functional stomata and globally reconfigures plant metabolism at the genomic level to enhance insect fitness. Although insect-induced stomata are rare in nature, the transcriptional pattern of gall formation is likely conserved among insect parasites and facilitates the galling habit by increasing competitive sink strength of the insect. The following chapters provide a framework for assessing how arthropod herbivores alter leaf function across damage type and plant species. By characterizing mechanisms within model systems, I believe I have uncovered some of the physiological costs of herbivory that modulate resource-driven trade-offs in nature

Seed Bank Viability of Inland Saline Wetland Sites in Agro-Ecosystems

Wetland restoration typically includes modifications to soils, flora, and hydrology. Will the return of wetland hydrology to former saline wetlands create conditions suitable for wetland taxa, especially saline wetland indicator species? To answer this question we evaluated the potential restoration efficacy of historical saline wetland soils by re-exposing them to wetland hydrological conditions simulated in a greenhouse. Agricultural lands contained no saline indicator plants and limited wetland species, likely due to significant and long-term land alteration. Restored wetlands showed only a few additional wetland taxa, and seeds of saline wetland plants emerged from soils of only one restored site. Because land alteration threatens the seed bank status of current saline wetlands, potential restoration sites, and even historical saline wetlands under agricultural production in Nebraska, preservation of existing sites that currently have saline dynamics and affluent seed banks may be the only means for continued restoration

Cognitive and Behavioral Associations with Hair Cortisol, Aldosterone, and Testosterone Levels in a Serious Mental Illness Population

Serious mental illness populations, including people with Schizophrenia diagnoses, tend have chronic longer term symptoms and needs for treatment and there is a need for measurement of tonic levels of steroids that are not easily influenced by diurnal cycle fluctuations that provide a more accurate account of total production of steroids over time. The literature shows mixed results for relationships between cortisol, aldosterone, and testosterone from blood, saliva, and urine which are subject to variabilities in diurnal cycles. Calculating total area under the curve using fluids requires repeated measurements through a 24 hour day. As hair provides a longer term record of steroids, participants from a community sample of individuals with serious mental illness including Schizophrenia Spectrum Disorder (SSD) and other diagnoses were recruited for a study to determine the viability of steroid measurement from hair samples. Several of the relationships found between steroids and stress, impulsivity, avoidance, aggression, and cognitive functioning from other sample types are also found in hair samples. Also, positive correlations were found for childhood sexual abuse with testosterone and childhood emotional abuse with aldosterone in the SSD population. The results of this study provide evidence of altered HPA-axis functioning in serious mental illness populations