Impact of postharvest exogenous γ-aminobutyric acid treatment on cucumber fruit in response to chilling tolerance

Low-temperature storage is generally used to extend postharvest lifetime and to inhibit decay of cucumber fruit, but it also enhances the intensity of chilling injury. The capability of γ-aminobutyric acid to enhance antioxidant enzyme activities and reduce chilling injury was studied in cucumber (Cucumis sativus L.) fruit stored at 1 °C for 5 weeks. The purpose of this study was to define if the GABA-induced modification in antioxidant system and phospholipase activity is linked to the reduced chilling injury in cold-stored cucumber fruit. Alleviation of chilling injury by GABA treatment was related to increased content of proline, endogenous GABA and enhanced activities of CAT and SOD, together with reduced activities of PLC, PLD and LOX. We suggest that PLC, LOX and PLD are associated with chilling injury initiation by involvement in a signaling pathway and membrane deterioration. Therefore the results obtained in this study suggest GABA’s potential for postharvest applications for reducing chilling injury symptom in cucumber fruit.     

Comparative proteomic analysis of whole saliva from chronic periodontitis patients

Chronic periodontal disease is a chronic inflammatory process affecting tooth supporting tissues in the presence of pathogenic bacterial biofilm. There is some evidence for changes in the protein composition of whole saliva from chronic periodontitis patients, but there have been no studies using a proteomic approach. Hence, the aim of this study was to compare the protein profiles of unstimulated whole saliva from patients with periodontitis and healthy subjects by two complementary approaches (2D-gel electrophoresis and liquid chromatography). Protein spots of interest were analyzed by MALDI-TOF-TOF, and the data was complemented by an ESI-Q-TOF experiment. The analyses revealed that subjects with periodontal disease have increased amounts of blood proteins (serum albumin and hemoglobin) and immunoglobulin, and they have a lower abundance of cystatin compared to the control group. A higher number of protein spots were observed in the periodontitis group, of which most were identified as alpha-amylase. This higher number of alpha-amylase variants seems to be caused by hydrolysis by cysteine proteases under such inflammatory conditions. This approach gives novel insights into alterations of salivary protein in presence of periodontal inflammation and may contribute to the improvement of periodontal diagnosis.     

Parent-offspring conflict and the evolution of infant-directed song

We present a theory of the origin and evolution of infant-directed song, a form of music found in many cultures. After examining the ancestral ecology of parent-infant relations, we propose that infant-directed song arose in an evolutionary arms race between parents and infants, stemming from the dynamics of parent-offspring conflict. We describe testable predictions that follow from this theory, consider some existing evidence for them, and entertain the possibility that infant-directed song could form the basis for the development of other, more complex forms of music.     

Effect of Prepartum Supplementation of Selenium and Vitamin E on Serum Se, IgG Concentrations and Colostrum of Heifers and on Hematology, Passive Immunity and Se Status of Their Offspring

Forty heifers at the late stage of gestation were randomly assigned into five groups. Heifers were balanced for age, weight, and time of calving in each group. Four and 2?weeks before expected time of calving, the heifers were injected with 0?ml (C), 10?ml (T1), 20?ml (T2), 30?ml (T3), and 40?ml (T4) Se and VE supplements, respectively. Each milliliter of the supplement contained of 0.5?mg Se as sodium selenite and 50?IU of dl-alpha-tocopheryl acetate. Blood samples were collected from the heifers 4?weeks before expected calving and at calving day and from the calves at birth and 7?days of age. The serum Se and immunoglobulin G (IgG) concentrations, white blood cell and differential leukocyte counts were measured. The Se concentrations in the sera of the heifers before the injections of Se and VE supplements were the same among the groups (P?>?0.05), but after calving were significantly increased in the treated heifers (P??0.05). The white blood cell counts were higher in calves of heifers in groups T3 and T4 compared with the control group at 7?days of age (P?相似文献   

Simulations of the NK cell immune synapse reveal that activation thresholds can be established by inhibitory receptors acting locally

NK cell activation is regulated by a balance between activating and inhibitory signals. To address the question of how these signals are spatially integrated, we created a computer simulation of activating and inhibitory NK cell immunological synapse (NKIS) assembly, implementing either a "quantity-based" inhibition model or a "distance-based" inhibition model. The simulations mimicked the observed molecule distributions in inhibitory and activating NKIS and yielded several new insights. First, the total signal is highly influenced by activating complex dissociation rates but not by adhesion and inhibitory complex dissociation rates. Second, concerted motion of receptors in clusters significantly accelerates NKIS maturation. Third, when the potential of a cis interaction between Ly49 receptors and MHC class I on murine NK cells was added to the model, the integrated signal as a function of receptor and ligand numbers was only slightly increased, at least up to the level of 50% cis-bound Ly49 receptors reached in the model. Fourth, and perhaps most importantly, the integrated signal behavior obtained when using the distance-based inhibition signal model was closer to the experimentally observed behavior, with an inhibition radius of the order 3-10 molecules. Microscopy to visualize Vav activation in NK cells on micropatterned surfaces of activating and inhibitory strips revealed that Vav is only locally activated where activating receptors are ligated within a single NK cell contact. Taken together, these data are consistent with a model in which inhibitory receptors act locally; that is, that every bound inhibitory receptor acts on activating receptors within a certain radius around it.     

Attenuation of multi-targeted proliferation-linked signaling by 3,3'-diindolylmethane (DIM): from bench to clinic

Emerging evidence provide credible support in favor of the potential role of bioactive products derived from ingesting cruciferous vegetables such as broccoli, brussel sprouts, cauliflower and cabbage. Among many compounds, 3,3'-diindolylmethane (DIM) is generated in the acidic environment of the stomach following dimerization of indole-3-carbinol (I3C) monomers present in these classes of vegetables. Both I3C and DIM have been investigated for their use in preventing, inhibiting, and reversing the progression of cancer - as a chemopreventive agent. In this review, we summarize an updated, wide-ranging pleiotropic anti-tumor and biological effects elicited by DIM against tumor cells. It is unfeasible to point one single target as basis of cellular target of action of DIM. We emphasize key cellular and molecular events that are effectively modulated in the direction of inducing apoptosis and suppressing cell proliferation. Collectively, DIM orchestrates signaling through Ah receptor, NF-κB/Wnt/Akt/mTOR pathways impinging on cell cycle arrest, modulation of key cytochrome P450 enzymes, altering angiogenesis, invasion, metastasis and epigenetic behavior of cancer cells. The ability of DIM to selectively induce tumor cells to undergo apoptosis has been observed in preclinical models, and thus it has been speculated in improving the therapeutic efficacy of other anticancer agents that have diverse molecular targets. Consequently, DIM has moved through preclinical development into Phase I clinical trials, thereby suggesting that DIM could be a promising and novel agent either alone or as an adjunct to conventional therapeutics such as chemo-radio and targeted therapies. An important development has been the availability of DIM formulation with superior bioavailability for humans. Therefore, DIM appears to be a promising chemopreventive agent or chemo-radio-sensitizer for the prevention of tumor recurrence and/or for the treatment of human malignancies.     

Genetic variation in RPOIILS gene encoding RNA polymerase II largest subunit from Leishmania major

Leishmaniasis is a geographically widespread severe disease which includes visceral leishmaniasis, cutaneous leishmaniasis (CL). There are 350 million people at risk in over 80 countries. In the Old World, CL is usually caused by Leishmania major, Leishmania tropica, and Leishmania aethiopica complex which 90 % of cases occurring in Afghanistan, Algeria, Iran, Iraq, Saudi Arabia, Syria, Brazil, and Peru. Recently, some reports showed that some strains of L. major have internal transcribed space (ITS-1) with differential size exhibiting homology with the related gene in a divergent genus of kinetoplastida, the Crithidia. This prompted us to analyze the mentioned gene in 100 isolates obtained from patients with suspected CL. After obtaining samples from 100 patients, DNA extraction was performed and ITS-1 was analyzed using PCR–RFLP. These samples were sequenced for verifying their homology. Then, RPOIILS gene was analyzed in the samples that their ITS-1 gene exhibiting homology with the related gene in Crithidia. Results showed that 10 % of the isolates have ITS-1 exhibiting different size with the routine ones. Sequencing of them showed their similarity to the one from Crithidia fasciculata. RPOIILS gene encoding RNA polymerase II largest subunit analysis showed genetic diversity. This study might also help in solving the problems concerning Leishmaniasis outbreak currently facing in Iran and some other endemic regions of the world.     

Stabilization of the ADP/Metaphosphate Intermediate during ATP Hydrolysis in Pre-power Stroke Myosin: QUANTITATIVE ANATOMY OF AN ENZYME*

It has been proposed recently that ATP hydrolysis in ATPase enzymes proceeds via an initial intermediate in which the dissociated γ-phosphate of ATP is bound in the protein as a metaphosphate (P_γO₃⁻). A combined quantum/classical analysis of this dissociated nucleotide state inside myosin provides a quantitative understanding of how the enzyme stabilizes this unusual metaphosphate. Indeed, in vacuum, the energy of the ADP³⁻·P_γO₃⁻·Mg²⁺ complex is much higher than that of the undissociated ATP⁴⁻. The protein brings it to a surprisingly low value. Energy decomposition reveals how much each interaction in the protein stabilizes the metaphosphate state; backbone peptides of the P-loop contribute 50% of the stabilization energy, and the side chain of Lys-185⁺ contributes 25%. This can be explained by the fact that these groups make strong favorable interactions with the α- and β-phosphates, thus favoring the charge distribution of the metaphosphate state over that of the ATP state. Further stabilization (16%) is achieved by a hydrogen bond between the backbone C=O of Ser-237 (on loop Switch-1) and a water molecule perfectly positioned to attack the P_γO₃⁻ in the subsequent hydrolysis step. The planar and singly negative P_γO₃⁻ is a much better target for the subsequent nucleophilic attack by a negatively charged OH⁻ than the tetrahedral and doubly negative P_γO₄²⁻ group of ATP. Therefore, we argue that the present mechanism of metaphosphate stabilization is common to the large family of nucleotide-hydrolyzing enzymes. Methodologically, this work presents a computational approach that allows us to obtain a truly quantitative conception of enzymatic strategy.