Induced SHIP deficiency expands myeloid regulatory cells and abrogates graft-versus-host disease

Graft-vs-host disease (GVHD) is the leading cause of treatment-related death in allogeneic bone marrow (BM) transplantation. Immunosuppressive strategies to control GVHD are only partially effective and often lead to life-threatening infections. We previously showed that engraftment of MHC-mismatched BM is enhanced and GVHD abrogated in recipients homozygous for a germline SHIP mutation. In this study, we report the development of a genetic model in which SHIP deficiency can be induced in adult mice. Using this model, we show that the induction of SHIP deficiency in adult mice leads to a rapid and significant expansion of myeloid suppressor cells in peripheral lymphoid tissues. Consistent with expansion of myeloid suppressor cells, splenocytes and lymph node cells from adult mice with induced SHIP deficiency are significantly compromised in their ability to prime allogeneic T cell responses. These results demonstrate that SHIP regulates homeostatic signals for these immunoregulatory cells in adult physiology. Consistent with these findings, induction of SHIP deficiency before receiving a T cell-replete BM graft abrogates acute GVHD. These findings indicate strategies that target SHIP could increase the efficacy and utility of allogeneic BM transplantation, and thereby provide a curative therapy for a wide spectrum of human diseases.     

Mechanism of activation of the Drosophila EGF Receptor by the TGFalpha ligand Gurken during oogenesis.

We have analyzed the mechanism of activation of the Epidermal growth factor receptor (Egfr) by the transforming growth factor (TGF) alpha-like molecule, Gurken (Grk). Grk is expressed in the oocyte and activates the Egfr in the surrounding follicle cells during oogenesis. We show that expression of either a membrane bound form of Grk (mbGrk), or a secreted form of Grk (secGrk), in either the follicle cells or in the germline, activates the Egfr. In tissue culture cells, both forms can bind to the Egfr; however, only the soluble form can trigger Egfr signaling, which is consistent with the observed cleavage of Grk in vivo. We find that the two transmembrane proteins Star and Brho potentiate the activity of mbGrk. These two proteins collaborate to promote an activating proteolytic cleavage and release of Grk. After cleavage, the extracellular domain of Grk is secreted from the oocyte to activate the Egfr in the follicular epithelium.     

A modified TILLING approach to detect induced mutations in tetraploid and hexaploid wheat

Background  

Wheat (Triticum ssp.) is an important food source for humans in many regions around the world. However, the ability to understand and modify gene function for crop improvement is hindered by the lack of available genomic resources. TILLING is a powerful reverse genetics approach that combines chemical mutagenesis with a high-throughput screen for mutations. Wheat is specially well-suited for TILLING due to the high mutation densities tolerated by polyploids, which allow for very efficient screens. Despite this, few TILLING populations are currently available. In addition, current TILLING screening protocols require high-throughput genotyping platforms, limiting their use.     

Field Infection of Zonocerus variegatus following application of an oil‐based formulation of Metarhizium flavoviride conidia

Conidia of Metarhizium flavoviride grown in diphasic culture with sporulation on rice, were extracted in kerosene and formulated with peanut oil. The formulation led to high mortality when applied to field populations of Zonocerus variegatus; between 70 and 95% of insects in samples collected from the field 0, 3 or 7 days after spraying died. Sporulation of M. flavoviride was observed in 70–80% of the dead‐treated insects, which compares favourably with results obtained in laboratory bioassays. Many dead Z. variegatus, some with internal sporulation, were found in shaded niches and oviposition sites in the treated plots. No sporulation was observed in samples collected prior to application, and both sporulation and mortality differed significantly between control and treated plots. Some infections were observed in insects collected 16 and 23 days after treatment; these late infections may be a consequence of contact with spores surviving in the environment.     

Expansion of myeloid suppressor cells in SHIP-deficient mice represses allogeneic T cell responses

Previously we demonstrated that SHIP(-/-) mice accept allogeneic bone marrow transplants (BMT) without significant acute graft-vs-host disease (GvHD). In this study we show that SHIP(-/-) splenocytes and lymph node cells are poor stimulators of allogeneic T cell responses that cause GvHD. Intriguingly, SHIP(-/-) splenocytes prime naive T cell responses to peptide epitopes, but, conversely, are partially impaired for priming T cell responses to whole Ag. However, dendritic cells (DC) purified from SHIP(-/-) splenocytes prime T cell responses to allogeneic targets, peptide epitopes, and whole Ag as effectively as SHIP(+/+) DC. These findings point to an extrinsic effect on SHIP(-/-) DC that impairs priming of allogeneic T cell responses. Consistent with this extrinsic effect, we found that a dramatic expansion of myeloid suppressor cells in SHIP(-/-) mice impairs priming of allogeneic T cells. These findings suggest that SHIP expression or its activity could be targeted to selectively compromise T cell responses that mediate GvHD and graft rejection.     

Maintenance and mass rearing of phytoseiid predators of the cassava green mite

The cassava green mite Mononychellus tanajoa (Bondar), accidentally introduced from South America into Africa, has spread across the cassava belt and is causing severe yield losses to cassava. Biological control was recognized as the most promising and sustainable strategy against this pest. Among the different stages of a biological control program, mass rearing of beneficials is often a major bottleneck. The different rearing systems used by the International Institute of Tropical Agriculture are described. A mother culture system maintains pure and high quality colonies and provides inoculum to start mass production. Twenty biotypes are maintained separately and no contamination has been found in the cultures. Oligophagous species are reared in the insectary on artificial substrate, using alternative prey as a food source. For phytoseiid species specific to M. tanajoa, an on plant system is used in a greenhouse. Advantages and disadvantages of the two different systems are discussed as well as general requirements and constraints in rearing phytoseiids.     

Inappropriate recruitment and activity by the Src homology region 2 domain-containing phosphatase 1 (SHP1) is responsible for receptor dominance in the SHIP-deficient NK cell

We have previously demonstrated that the NKR repertoire is profoundly disrupted by SHIP deficiency. This repertoire disruption is characterized by receptor dominance where inhibitory signals from 2B4 repress killing of complex targets expressing MHC class I and activating ligands. In this study, we examine the molecular basis of receptor dominance in SHIP-/- NK cells. In this study, we show that in SHIP-/- NK cells there is a pronounced bias toward the 2B4 long isoform. We have also characterized signaling molecules recruited to 2B4 in SHIP-/- NK cells. Interestingly, we find that approximately 10- to 16-fold more Src homology region 2 domain-containing phosphatase 1 (SHP1) is recruited to 2B4 in SHIP-/- NK cells when compared with wild type. Consistent with SHP1 overrecruitment, treatment with sodium orthovanadate or a novel inhibitor with micromolar activity against SHP1 restores the ability of SHIP-/- NK cells to kill Rae1+ RMA and M157+ targets. These findings define the molecular basis for hyporesponsiveness by SHIP-deficient NK cells.     

Cutting edge: dominance by an MHC-independent inhibitory receptor compromises NK killing of complex targets

Inhibitory receptors that recognize MHC class I molecules regulate NK cell responses and self-tolerance. Recent evidence indicates that self-ligands not present in the MHC locus also can modulate NK function. In this study, we show that an inhibitory receptor that recognizes an MHC-independent ligand is over expressed in SHIP(-/-) mice at all stages of NK development and differentiation. Overexpression of this receptor compromises key cytolytic NK functions, including killing of allogeneic, tumor, and viral targets. These results further demonstrate the critical role that SHIP plays in regulation of the NK receptor repertoire and show that regulation of MHC-independent inhibitory receptors is crucial for NK recognition and cytolysis of complex targets.     

Opportunities for improving risk communication during the permitting process for entomophagous biological control agents: a review of current systems

Concerns about potentially irreversible non-target impacts from the importation and release of entomophagous biological control agents (BCAs) have resulted in increasingly stringent national import requirements by National Plant Protection Organizations worldwide. However, there is a divergence of opinions among regulators, researchers, environmentalists, and the general public on ways to appropriately manage associated risks. Implementation of a comprehensive and effective risk communication process might narrow the opinion gaps. Results from a comprehensive survey conducted in the United States were used to describe communication habits of stakeholders involved in biological control and identify areas that are fundamental in an efficient process. In addition, this study critically reviews risk communication practices and how phytosanitary decisions are communicated in the permitting systems for entomophagous BCAs of several countries to identify risk communication tools used in an effective risk communication framework. The following barriers to efficient risk communication were identified: absence of a formalized risk communication process, undefined risk communication goals and target audiences, lack of credibility and objectivity of information sources, inefficiency of mode of distribution of messages, insufficient public participation, and lack of transparency of decision making processes. This paper suggests the creation and/or enhancement of modes of distribution of risk messages to increase coverage, understanding, and guidance. For instance, messages should be presented in different formats such as internet, brochures, and newspapers. Surveys, public meetings, and trainings/workshops are tools that can be used to characterize stakeholders’ diversity and develop risk messages specific to the targeted audience. Implementation of a participatory decision making process will increase stakeholder involvement and trust in the risk management plan. Development of practical mechanisms, such as public hearings will increase all stakeholders’ involvement in the risk assessment process. A clear framework describing how public comments will be incorporated in the decision making process should be implemented. Finally, to ensure a streamlined risk communication process, there must be consistency in the messages disseminated by federal, state, and local agencies.