Studies on some plant species have shown that increasing the growth temperature gradually or pretreating with high temperature can lead to obvious photosynthetic acclimation to high temperature. To test whether this acclimation arises from heat adaptation of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39) activation mediated by Rubisco activase (RCA), gene expression of RCA large isoform (RCA(L)) and RCA small isoform (RCA(S)) in rice was determined using a 4-day heat stress treatment [40/30 degrees C (day/night)] followed by a 3-day recovery under control conditions [30/22 degrees C (day/night)]. The heat stress significantly induced the expression of RCA(L) as determined by both mRNA and protein levels. Correlative analysis indicated that RCA(S) protein content was extremely significantly related to Rubisco initial activity and net photosynthetic rate (Pn) under both heat stress and normal conditions. Immunoblot analysis of the Rubisco-RCA complex revealed that the ratio of RCA(L) to Rubisco increased markedly in heat-acclimated rice leaves. Furthermore, transgenic rice plants expressing enhanced amounts of RCA(L) exhibited higher thermotolerance in Pn and Rubisco initial activity and grew better at high temperature than wild-type (WT) plants and transgenic rice plants expressing enhanced amounts of RCA(S). Under normal conditions, the transgenic rice plants expressing enhanced amounts of RCA(S) showed higher Pn and produced more biomass than transgenic rice plants expressing enhanced amounts of RCA(L) and wild-type plants. Together, these suggest that the heat-induced RCA(L) may play an important role in photosynthetic acclimation to moderate heat stress in vivo, while RCA(S) plays a major role in maintaining Rubisco initial activity under normal conditions.

The proximate analysis, amino acid content and true amino acid digestibility and TMEn for poultry of adult Field crickets Gryllus testaceus Walker, were investigated. The insect was also used as partial replacement of protein supplements in the broiler diet on an equal CP percentage and TMEn basis. The results indicated that the adult insect contained: crude protein 58.3%; fat 10.3%, chitin 8.7% and ash 2.96% on dry matter basis, respectively. The total amounts of methionine, cystine and lysine in the Field crickets were 1.93%, 1.01% and 4.79%, respectively, and their true digestibility coefficients, determined in cecectomized roosters, were 94.1%, 85% and 96%, respectively. The TMEn of this insect meal was 2,960 kcal/kg determined in cecectomized roosters. When cornsoybean meal diets were formulated on an equal CP percentage and TMEn basis, up to 15% Field cricket could replace control diet without any adverse affects on broiler weight gain, feed intake or gain:feed ratio from 8 to 20 d posthatching.

Acrylamide (ACR) is a potent toxin that affects the human nervous system. However, the underlying mechanism of ACR neurotoxicity remains poorly understood. In the present study, we investigated whether ACR induces mitochondrion-dependent apoptosis and the involved signaling pathways in PC12 cells. ACR exposure activated the mitochondrial apoptotic pathway in PC12 cells and triggered the up-regulation of Bax/Bcl-2 ratio, excessive release of cytochrome c, cleavage of capase-9 and caspase-3, depolarization of the mitochondrial membrane, structural damages to the mitochondria, and compaction of nuclear heterochromatin. ACR-induced oxidative stress was also observed based on distinct increase in cellular reactive oxygen species (ROS) and malondialdehyde (MDA), and significant decrease in glutathione (GSH). Mitogen-activated protein kinases (MAPK) signaling including extracellular signal-regulated protein kinases (ERK), c-Jun N-terminal kinases (JNK), and p38 were phosphorylated by ROS overproduction in PC12 cells in a time-and dose-dependent manner. ACR promoted the translocation of nuclear factor E2-related factor 2 (Nrf2) from the cytosol to the nucleus, thereby enhancing the expression of downstream γ-glutamyl-cysteine synthetase (γ-GCS). The regulation of Nrf2 activation by MAPK pathways was confirmed by the blockade of MAPK pathways. The suppression of JNK and p38 pathways showed a protective effect on ACR-induced mitochondrial dysfunction and apoptosis. Nrf2 knockdown further enhanced MDA production and reduced GSH generation induced by ACR. These results suggest that MAPK and Nrf2 signaling pathways contribute to mitochondrion-mediated apoptosis induced by ACR in PC12 cells.

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Previous investigations have implicated glutathione S-transferases (GSTs) as one of the major reasons for insecticide resistance. Therefore, effectiveness of new candidate compounds depends on their ability to inhibit GSTs to prevent metabolic detoxification by insects. Cantharidin, a terpenoid compound of insect origin, has been developed as a bio-pesticide in China, and proves highly toxic to a wide range of insects, especially lepidopteran. In the present study, we test cantharidin as a model compound for its toxicity, effects on the mRNA transcription of a model Helicoverpa armigera glutathione S-transferase gene (HaGST) and also for its putative inhibitory effect on the catalytic activity of GSTs, both in vivo and in vitro in Helicoverpa armigera, employing molecular and biochemical methods. Bioassay results showed that cantharidin was highly toxic to H. armigera. Real-time qPCR showed down-regulation of the HaGST at the mRNA transcript ranging from 2.5 to 12.5 folds while biochemical assays showed in vivo inhibition of GSTs in midgut and in vitro inhibition of rHaGST. Binding of cantharidin to HaGST was rationalized by homology and molecular docking simulations using a model GST (1PN9) as a template structure. Molecular docking simulations also confirmed accurate docking of the cantharidin molecule to the active site of HaGST impeding its catalytic activity.