Heterologous expression of cyanobacterial gas vesicle proteins in Saccharomyces cerevisiae

Given the potential applications of gas vesicles (GVs) in multiple fields including antigen-displaying and imaging, heterologous reconstitution of synthetic GVs is an attractive and interesting study that has translational potential. Here, we attempted to express and assemble GV proteins (GVPs) into GVs using the model eukaryotic organism Saccharomyces cerevisiae. We first selected and expressed two core structural proteins, GvpA and GvpC from cyanobacteria Anabaena flos-aquae and Planktothrix rubescens, respectively. We then optimized the protein production conditions and validated GV assembly in the context of GV shapes. We found that when two copies of anaA were integrated into the genome, the chromosomal expression of AnaA resulted in GV production regardless of GvpC expression. Next, we co-expressed chaperone-RFP with the GFP-AnaA to aid the AnaA aggregation. The co-expression of individual chaperones (Hsp42, Sis1, Hsp104, and GvpN) with AnaA led to the formation of larger inclusions and enhanced the sequestration of AnaA into the perivacuolar site. To our knowledge, this represents the first study on reconstitution of GVs in S. cerevisiae. Our results could provide insights into optimizing conditions for heterologous protein production as well as the reconstitution of other synthetic microcompartments in yeast.     

Marine living resources management in the ASEAN region: lessons learned and the integrated management approach

This paper reviews the marine living resources management practices in the ASEAN region. Lessons learned from past management of these resources are highlighted with an analysis of impacts. The lack of an appropriate management policy at national and regional levels, inefficient enforcement measures, the rapid population growth and unsustainable economic development have all contributed to the degradation of the resource base in the marine environment of many ASEAN members.The need to establish a holistic and integrated management approach as well as action plans to mitigate the accelerated deterioration of the marine environmental quality and to promote sustainable use of resources is strongly emphasized in this paper. Recent changes in government policies in ASEAN towards sustainable development could provide valuable opportunities to arrest further resource depletion. The ASEAN initiation of integrated management of marine resources is a step towards the right direction.     

Sensitivity to Chronic Methamphetamine Administration and Withdrawal in Mice with Relaxin-3/RXFP3 Deficiency

Methamphetamine (METH) is a highly addictive psychostimulant, and cessation of use is associated with reduced monoamine signalling, and increased anxiety/depressive states. Neurons expressing the neuropeptide, relaxin-3 (RLN3), and its cognate receptor, RXFP3, constitute a putative ‘ascending arousal system’, which shares neuroanatomical and functional similarities with serotonin (5-HT)/dorsal raphe and noradrenaline (NA)/locus coeruleus monoamine systems. In light of possible synergistic roles of RLN3 and 5-HT/NA, endogenous RLN3/RXFP3 signalling may compensate for the temporary reduction in monoamine signalling associated with chronic METH withdrawal, which could alter the profile of ‘behavioural despair’, bodyweight reductions, and increases in anhedonia and anxiety-like behaviours observed following chronic METH administration. In studies to test this theory, Rln3 and Rxfp3 knockout (KO) mice and their wildtype (WT) littermates were injected once daily with saline or escalating doses of METH (2 mg/kg, i.p. on day 1, 4 mg/kg, i.p. on day 2 and 6 mg/kg, i.p. on day 3–10). WT and Rln3 and Rxfp3 KO mice displayed an equivalent sensitivity to behavioural despair (Porsolt swim) during the 2-day METH withdrawal and similar bodyweight reductions on day 3 of METH treatment. Furthermore, during a 3-week period after the cessation of chronic METH exposure, Rln3 KO, Rxfp3 KO and corresponding WT mice displayed similar behavioural responses in paradigms that measured anxiety (light/dark box, elevated plus maze), anhedonia (saccharin preference), and social interaction. These findings indicate that a whole-of-life deficiency in endogenous RLN3/RXFP3 signalling does not markedly alter behavioural sensitivity to chronic METH treatment or withdrawal, but leave open the possibility of a more significant interaction with global or localised manipulations of this peptide system in the adult brain.     

Phenotypic and functional alterations of Vγ2Vδ2 T cell subsets in patients with active nasopharyngeal carcinoma

Introduction  Human Vγ2Vδ2 T cells play important role in immunity to infection and cancer by monitoring self and foreign isoprenoid metabolites with their γδ T cell antigen receptors. Like CD4 and CD8 αβ T cells, adult peripheral Vγ2Vδ2 T cells represent a pool of heterogeneous cells with distinct functional capabilities. Purpose  The aim of this study was to characterize the phenotypes and functions of various Vγ2Vδ2 T cell subsets in patients with nasopharyngeal carcinoma (NPC). We sought to develop a better understanding of the role of these cells during the course of disease and to facilitate the development of immunotherapeutic strategies against NPC. Results  Although similar total percentages of peripheral blood Vγ2Vδ2 T cells were found in both NPC patients and normal donors, Vγ2Vδ2 T cells from NPC patients showed decreased cytotoxicity against tumor cells whereas Vγ2Vδ2 T cells from normal donors showed potent cytotoxicity. To investigate further, we compared the phenotypic characteristics of Vγ2Vδ2 T cells from 96 patients with NPC and 54 healthy controls. The fraction of late effector memory Vγ2Vδ2 T cells (T_{EM RA}) was significantly increased in NPC patients with corresponding decreases in the fraction of early memory Vγ2Vδ2 T cells (T_CM) compared with those in healthy controls. Moreover, T_{EM RA} and T_CM Vγ2Vδ2 cells from NPC patients produced significantly less IFN-γ and TNF-α, potentially contributing to their impaired cytotoxicity. Radiotherapy or concurrent chemo-radiotherapy further increased the T_{EM RA} Vγ2Vδ2 T cell population but did not correct the impaired production of IFN-γ and TNF-α observed for T_{EM RA} Vγ2Vδ2 T cells. Conclusion  We have identified distinct alterations in the Vγ2Vδ2 T cell subsets of patients with NPC. Moreover, the overall cellular effector function of γδ T cells is compromised in these patients. Our data suggest that the contribution of Vγ2Vδ2 T cells to control NPC may depend on the activation state and differentiation of these cells. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The essential elements of science and management in coastal environmental managements

Coastal environmental management requires timely and appropriate policy, management and technological interventions to address a host of interrelated environmental problems arising from unplanned and unregulated coastal developments. These interventions can only be effective if they are based on sound scientific (including socioeconomic) information. Thus, science plays a significant role in the environmental management of coastal and marine areas. This paper highlights the essential components of environmental coastal management that require scientific interventions, particularly in providing the scientific basis for policy interventions, and preventive and/or mitigating measures. The integration and packaging of scientific information for management actions require an interdisciplinary effort to address identified management problems. Scientific research should respond to management needs and make contributions to the better understanding of ecosystems and their responses to human interventions. Scientific information urgently required for management includes an understanding of interactions in coastal resource systems, identification, evaluation and prioritization of management issues, management strategies and actions, and development of methodologies and tools for environmental management. Obstacles to management-oriented research have also been identified to include defective perception among scientists, defective communication between scientists and decision makers, intellectual and cultural arrogance, and inadequate technical and management capability at the local level. This revised version was published online in August 2006 with corrections to the Cover Date.