Plant wound compounds from oviposition scars used in host discrimination by a stem-galling sawfly

The stem-galling sawfly Euura lasiolepisuses one or more plant wound compounds resulting from oviposition scars as cues in host discrimination (avoiding sites occupied by conspecifics). Four experiments were conducted to test hypotheses about how Euurapartitions resources. Experiment 1 demonstrated that Euuraavoids ovipositing on nodes with scars from previous ovipositions. Experiment 2 showed no evidence that the sawfly uses oviposition-deterring pheromones and indicated there is a time lag following oviposition before the oviposition scar becomes a deterrent. Experiment 3 showed that sawflies avoid artificially formed scars, demonstrating that a plant cue alone can lead to host discrimination. Experiment 4 showed that visual or tactile cues are not necessary for host discrimination and indicated that a plant wound compound functions as an oviposition deterrent. Both experimental results and field surveys showed that Euuraoviposition scars were more uniformly distributed than expected if sawflies were ignoring previous ovipositions.     

Targeted disruption of LIG-1 gene results in psoriasiform epidermal hyperplasia

We have designed a chimeric promoter that can be stimulated by various pro-inflammatory mediators and so drive the expression of therapeutic genes under inflammatory conditions. The promoter has two parts, the [-247/+20] fragment of the human type IIA secreted phospholipase A2 gene promoter, which is stimulated by the pro-inflammatory cytokine interleukin-1beta (IL-1beta), and a double peroxisome proliferator-activated receptor response element that is activated by some eicosanoids and by non-steroidal anti-inflammatory drugs (NSAIDs). Transfection experiments using rabbit articular chondrocytes in primary culture showed that this chimeric promoter produced a low basal activity and was induced by NSAIDs, WY-14643, IL-1beta, and 15-deoxy Delta12,14 prostaglandin J2. The latter two compounds stimulated the promoter synergistically.     

Stat3 links activated keratinocytes and immunocytes required for development of psoriasis in a novel transgenic mouse model

Here we report that epidermal keratinocytes in psoriatic lesions are characterized by activated Stat3. Transgenic mice with keratinocytes expressing a constitutively active Stat3 (K5.Stat3C mice) develop a skin phenotype either spontaneously, or in response to wounding, that closely resembles psoriasis. Keratinocytes from K5.Stat3C mice show upregulation of several molecules linked to the pathogenesis of psoriasis. In addition, the development of psoriatic lesions in K5.Stat3C mice requires cooperation between Stat3 activation in keratinocytes and activated T cells. Finally, abrogation of Stat3 function by a decoy oligonucleotide inhibits the onset and reverses established psoriatic lesions in K5.Stat3C mice. Thus, targeting Stat3 may be potentially therapeutic in the treatment of psoriasis.     

An engineered chaperonin caging a guest protein: Structural insights and potential as a protein expression tool

The structure of a chaperonin caging a substrate protein is not quite clear. We made engineered group II chaperonins fused with a guest protein and analyzed their structural and functional features. Thermococcus sp. KS-1 chaperonin alpha-subunit (TCP) which forms an eightfold symmetric double-ring structure was used. Expression plasmids were constructed which carried two or four TCP genes ligated head to tail in phase and a target protein gene at the 3' end of the linked TCP genes. Electron microscopy showed that the expressed gene products with the molecular sizes of ~120 kDa (di-TCP) and ~230 kDa (tetra-TCP) formed double-ring complexes similar to those of wild-type TCP. The tetra-TCP retained ATPase activity and its thermostability was significantly higher than that of the wild type. A 260-kDa fusion protein of tetra-TCP and green fluorescent protein (GFP, 27 kDa) was able to form the double-ring complexes with green fluorescence. Image analyses indicated that the GFP moiety of tetra-TCP/GFP fusion protein was accommodated in the central cavity, and tetra-TCP/GFP formed the closed-form similar to that crystallographically resolved in group II chaperonins. Furthermore, it was suggested that caging GFP expanded the cavity around the bottom. Using this tetra-TCP fusion strategy, two virus structural proteins (21-25 kDa) toxic to host cells or two antibody fragments (25-36 kDa) prone to aggregate were well expressed in the soluble fraction of Escherichia coli. These fusion products also assembled to double-ring complexes, suggesting encapsulation of the guest proteins. The antibody fragments liberated by site-specific protease digestion exhibited ligand-binding activities.     

Lrig1 controls intestinal stem-cell homeostasis by negative regulation of ErbB signalling

Maintenance of adult tissues is carried out by stem cells and is sustained throughout life in a highly ordered manner. Homeostasis within the stem-cell compartment is governed by positive- and negative-feedback regulation of instructive extrinsic and intrinsic signals. ErbB signalling is a prerequisite for maintenance of the intestinal epithelium following injury and tumour formation. As ErbB-family ligands and receptors are highly expressed within the stem-cell niche, we hypothesize that strong endogenous regulators must control the pathway in the stem-cell compartment. Here we show that Lrig1, a negative-feedback regulator of the ErbB receptor family, is highly expressed by intestinal stem cells and controls the size of the intestinal stem-cell niche by regulating the amplitude of growth-factor signalling. Intestinal stem-cell maintenance has so far been attributed to a combination of Wnt and Notch activation and Bmpr inhibition. Our findings reveal ErbB activation as a strong inductive signal for stem-cell proliferation. This has implications for our understanding of ErbB signalling in tissue development and maintenance and the progression of malignant disease.     

A new IFN-like cytokine, limitin, modulates the immune response without influencing thymocyte development.

A novel IFN-like molecule, limitin, was recently identified and revealed to suppress B lymphopoiesis through the IFN-alphabeta receptor, although it lacked growth suppression on myeloid and erythroid progenitors. Here we have studied diverse effects of limitin on T lymphocytes and compared limitin with previously known IFNs. Like IFN-alpha and -beta, limitin modified immunity in the following responses. It suppressed mitogen- and Ag-induced T cell proliferation through inhibiting the responsiveness to exogenous IL-2 rather than suppressing the production of IL-2. In contrast, limitin enhanced cytotoxic T lymphocyte activity associated with the perforin-granzyme pathway. To evaluate the effect of limitin in vivo, a lethal graft-versus-host disease assay was established. Limitin-treatment of host mice resulted in the enhancement of graft-versus-host disease. Limitin did not influence thymocyte development either in fetal thymus organ cultures or in newborn mice injected with limitin-Ig, suggesting that limitin is distinguishable from IFN-alpha and -beta. From these findings, it can be speculated that the human homolog of limitin may be applicable for clinical usage because of its IFN-like activities with low adverse effects on, for example, T lymphopoiesis, erythropoiesis, and myelopoiesis.     

The influence of oviposition phenology on survival in host races of Eurosta solidaginis

Phenological differences between host plants can contribute to allochronic isolation of host races of phytophagous insects. Host races of the gallmaking fly, Eurosta solidaginis, that live on different species of goldenrod (Solidago altissima and S. gigantea) exhibit different emergence phenologies. These differences could result from adaptation to corresponding phenological differences between the hosts in periods of optimal suitability for gall formation and survival to adulthood. In order to test this, some flies of each host race were allowed to emerge naturally while the emergence times of others were manipulated to correspond to the emergence and oviposition periods of the other host race. Percent gall formation and survival to adulthood were examined for three oviposition periods: the peak time of emergence and oviposition of the earlier-emerging host race (that from S. gigantea), that of the later-emerging host race (that from S. altissima), and a week after the peak emergence of the host race from S. altissima. Flies of both host races were allowed to ovipuncture plants of the appropriate species during each of these periods. Plant relative growth rates were measured during each of these periods. The experiment was repeated twice over a two-year period. Relative growth rates of both host species were highest during the earliest oviposition period (the period during which the host race from S. gigantea normally emerges). Percent gall formation was significantly correlated with plant relative growth rate, but the coefficient of determination was low. In both years of the study, percent gall formation of both host races was highest during the earliest oviposition period (the period during which the host race from S. gigantea normally oviposits). Likewise, percent survival to adulthood in both host races was highest during the earliest oviposition period. There was no significant effect of oviposition period on the percent of larval death due to parasitism by Eurytoma gigantea or predation by Mordellistena unicolor. These results suggest that the host race from S. altissima does not emerge at the time that its host is optimally suited for gall formation or survival to adulthood. Therefore, differences in emergence phenologies do not appear to be due to corresponding phenological differences between the host species in suitability for gall formation or survival to adulthood.     

Identification of cDNA encoding Toll receptor, MjToll gene from kuruma shrimp, Marsupenaeus japonicus

Toll receptors are cell-surface receptors acting as pattern recognition receptors (PRRs) that are involved in the signaling pathway for innate immunity activation and are genetically conserved from insects to mammals. Tolls from penaeid shrimp are found in white leg shrimp Litopenaeus vannamei (lToll) and black tiger shrimp Penaeus monodon (PmToll). However, the molecular ligand-recognition patterns and identification of these penaeid Toll classes remain unknown. Here, we report cDNA cloning of a new type of Toll receptor gene (MjToll) from kuruma shrimp, Marsupenaeus japonicus, and the modulation of expression by immunostimulation. The full length cDNA of MjToll gene has 3095 nucleotides coding for a putative protein of 1009 amino acids. The MjToll gene is constitutively expressed in the gill, gut, lymphoid organ, heart, hematopoietic organ, hemocyte, ventral abdominal nerve cord, eyestalk neural ganglia and brain tissues. The MjToll gene expression was significantly increased (76-fold) as compared to a control in lymphoid organ stimulated with peptidoglycan at 12h, in vitro. lToll gene showed high similarity to PmToll gene with 96.9% identity; however, MjToll gene exhibited a percentage identity of 59% with that of penaeid Toll homologues. Therefore, this suggests that the identified MjToll gene belongs to the other class of Toll receptors in shrimp.