6个猕猴桃品种的果实贮藏与品质评价

为了选育耐贮藏且风味品质优异的猕猴桃(Actinidia)新品种,对美味猕猴桃(A.deliciosa)的3个野生品种‘kvf54’、‘kvf6’、‘鑫美’和3个栽培种‘秦美’、‘华美’、‘徐香’的品质和贮藏特性等进行比较分析。结果表明,常温和1℃贮藏下‘kvf54’和‘徐香’的硬度下降趋势相近,优于其他品种,且‘kvf54’的维生素C (V_C)含量最高。而在相同贮藏条件下,‘鑫美’可溶性固形物含量积累速度最快,淀粉和可滴定酸含量最少,贮藏性能不佳。‘kvf54’相比于其他品种的贮藏性更好,V_C、糖类物质等含量高,是可用于培育耐贮藏新品种的优质材料。     

Conjugates of adenosine mimetics and arginine-rich peptides serve as inhibitors and fluorescent probes but not as long-lifetime photoluminescent probes for protein arginine methyltransferases

The conjugates of an adenosine mimetic and oligo-l -arginine or oligo-d -arginine (ARCs) were initially designed in our research group as inhibitors and photoluminescent probes targeting basophilic protein kinases. Here, we explored a panel of ARCs and their fluorescent derivatives in biochemical assays with members of the protein arginine methyltransferase (PRMT) family, focusing specifically on PRMT1. In the binding/displacement assay with detection of fluorescence anisotropy, we found that ARCs and arginine-rich peptides could serve as high-affinity ligands for PRMT1, whereas the equilibrium dissociation constant values depended dramatically on the number of arginine residues within the compounds. The fluorescently labeled probe ARC-1081 was displaced from its complex with PRMT1 by both S-adenosyl-l -methionine (SAM) and S-adenosyl-l -homocysteine (SAH), indicating binding of the adenosine mimetic of ARCs to the SAM/SAH-binding site within PRMT1. The ARCs that had previously shown microsecond-lifetime photoluminescence in complex with protein kinases did not feature such property in complex with PRMT1, demonstrating the selectivity of the time-resolved readout format. When tested against a panel of PRMT family members in single-dose inhibition experiments, a micromolar concentration of ARC-902 was required for the inhibition of PRMT1 and PRMT7. Overall, our results suggest that the compounds containing multiple arginine residues (including the well-known cell-penetrating peptides) are likely to inhibit PRMT and thus interfere with the epigenetic modification status in complex biological systems, which should be taken into consideration during interpretation of the experimental data.     

AREL1 resists the apoptosis induced by TGF-β by inhibiting SMAC in vascular endothelial cells

Abnormal apoptosis of vascular endothelial cells is an important feature of arteriosclerosis (AS). Here, we induced apoptosis in human umbilical vein endothelial cells (HUVECs) using transforming growth factor-β (TGF-β), and investigated the role of antiapoptotic E3 ubiquitin ligase (AREL1) in the apoptosis of vascular endothelial cells. We proved that AREL1 is downregulated in TGF-β treated HUVECs. The overexpression of AREL1 inhibits the activation of Caspase-3 and Caspase-9 and attenuates cell apoptosis induced by TGF-β. According to the result of coimmunoprecipitation, AREL1 interacts with the proapoptotic proteins the second mitochondria-derived activator of caspases (SMAC) in TGF-β treated HUVECs. In addition, miR-320b inhibits the expression of AREL1, and the overexpression of AREL1 attenuates the apoptosis induced by miR-320b mimics in HUVECs. In conclusion, AREL1 is downregulated by miR-320b. AREL1 overexpression inhibits TGF-β induced apoptosis through downregulating SMAC in vascular endothelial cells. Our study explores pathogenesis regulation mechanism and new biological therapeutic targets for vascular disease.     

Somatic embryo maturation from long-term suspension cultures of white spruce (Picea glauca)

Summary The production of cotyledonary somatic embryos of white spruce from cultures grown long-term as suspensions was investigated. We report the effects of removal of 2,4-dichlorophenoxyacetic acid (2,4-D) from the maintenance medium (ordinarily containing both 2,4-D and benzyl adenine) before (±)-ABA-stimulated maturation. In particular the use of a 1-wk culture period without 2,4-D was found to improve the production of normal-looking cotyledonary somatic embryos. Using high performance liquid chromatography analyses of culture supernatants, it was determined that this affect was not related to altered ABA metabolism. Germination of cotyledonary somatic embryos from cultures pretreated by the 1-wk culture period without 2,4-D was improved compared with similar embryos from cultures that had not been pretreated.     

Influence of ovule perforation,plant growth regulators,andl-glutamine on in vitro growth of immature peach embryos

Summary Ovule perforation technique and media components (plant growth regulators andl-glutamine) were tested on in vitro growth of immature (<3 mm) embryos of “Springcrest” and “Earligrande” peaches. Ovule perforation was 2 to 4 times more effective in promoting embryo growth than leaving ovules intact.l-Glutamine (400 mg·liter⁻¹) promoted an increase in growth but could not be used with indole-acetic acid plus kinetin because an antagonistic effect on embryo growth occurred. The use of these exogenous plant growth regulators did not increase embryo growth over in vivo growth.     

Chemistry and biology of enzymes in protein glutathionylation

Protein S-glutathionylation is emerging as a central oxidation that regulates redox signaling and biological processes linked to diseases. In recent years, the field of protein S-glutathionylation has expanded by developing biochemical tools for the identification and functional analyses of S-glutathionylation, investigating knockout mouse models, and developing and evaluating chemical inhibitors for enzymes involved in glutathionylation. This review will highlight recent studies of two enzymes, glutathione transferase omega 1 (GSTO1) and glutaredoxin 1 (Grx1), especially introducing their glutathionylation substrates associated with inflammation, cancer, and neurodegeneration and showcasing the advancement of their chemical inhibitors. Lastly, we will feature protein substrates and chemical inducers of LanC-like protein (LanCL), the first enzyme in protein C-glutathionylation.     

Common Epitopes In the Circumsporozoite Proteins of Plasmodium Berghei and Plasmodium Gallinaceum Identified By Monoclonal Antibodies to the P. Gallinaceum Circumsporozoite Protein

ABSTRACT. Monoclonal antibodies that react with the circumsporozoite protein of the avian malaria Plasmodium gallinaceum sporozoites also reacted with circumsporozoite protein of the rodent malaria Plasmodium berghei. Two types of reactivity were identified: 1) two monoclonal antibodies reacted with P. berghei sporozoite protein by enzyme-linked immunosorbent assay, Western blot and indirect immunofluorescence antibody, 2) six other monoclonal antibodies reacted with P. berghei sporozoites by ELISA and Western blot only. We studied whether these differences could be explained by reactivity in enzyme-linked immunosorbent assay with different P. berghei circumsporozoite peptides. Although all P. gallinaceum monoclonal antibodies reacted with the P. berghei repeats, the first group reacted with a conserved peptide sequence, N1, whereas the second group did not. These results suggest that circumsporozoite proteins from P. gallinaceum and P. berghei share common epitopes. the biological significance of our finding is not yet clear. Indeed, the cross-reactive monoclonal antibodies giving a positive indirect immunofluorescence antibody with the P. berghei sporozoites only caused a borderline effect on the living P. berghei parasites in vitro as measured by inhibition of sporozoite infectivity.     

Differential distribution of calpain in human lymphoid cells

Calpain, a calcium-activated neutral proteinase, is ubiquitously present in human tissues. To determine if lymphoid cells implicated in pathogenesis of demyelination may harbor calpain in a functionally active form, we determined both Calpain and mCalpain activities in human lymphoid cell lines. DEAE-cellulose and phenylsepharose column chromatography were used to isolate the enzyme from the natural inhibitor, calpastatin. Lymphocytic lines (CCRF-CEM, MOLT-3, MOLT-4, M.R.) showed predominance of Calpain (55–80%) whereas the monocytic line (U-937) showed prodominance of mCalpain (77%). Proportion and subcellular distribution of both isoforms varied among cell lines. Calpains isolated from U-937 cells degraded myelin basic protein. These results indicate that human lymphoid cells harbor functionally active calpain that can degrade myelin components in vitro. The study suggests a degradative role for calpain in demyelinating diseases.     

Second messenger and protein phosphorylation mechanisms underlying opiate addiction: Studies in the rat locus coeruleus

We have studied the role of second messenger and protein phosphorylation pathways in mediating changes in neuronal function associated with opiate addiction in the rat locus coeruleus. We have found that chronic opiates increase levels of the G-protein subunits Gi and Go, adenylate cyclase, cyclic AMP-dependent protein kinase, and a number of phosphoproteins (including tyrosine hydroxylase) in this brain region. Electrophysiological data have provided direct support for the view that this up-regulation of the cyclic AMP system contributes to opiate tolerance, dependence, and withdrawal exhibited by these neurons. As the adaptations in G-proteins and the cyclic AMP system appear to occur at least in part at the level of gene expression, current efforts are aimed at identifying the mechanisms, at the molecular level, by which opiates regulate the expression of these intracellular messenger proteins in the locus coeruleus. These studies will lead to an improved understanding of the biochemical basis of opiate addiction.Special issue dedicated to Dr. Paul Greengard     

N-Terminal arginylation of proteins in explants of injured sciatic nerves and embryonic brains of rats

Posttranslational modification of proteins by arginine and lysine has been demonstrated in crude extracts of vertebrate nerves and brain but not in intact cells. In the present experiments we have exploited the fact that Arg is added posttranslationally only at the N-terminus of target proteins, to demonstrate these reactions in intact cells of sciatic nerves and embryonic brains of rats. Sciatic nerves were crushed in anaesthesized rats and 2 hrs later segments of nerve, including the site of the crush, were removed and incubated in media containing [³H]Arg. Incorporation of [³H]Arg into total proteins was analyzed by acid precipitation and the presence of label at the N-terminus was determined by a modification of the Edman degradation procedure. Approximately 25% of protein bound [³H]Arg was released from the N-terminus by the Edman reaction indicating that it was added posttranslationally rather than through protein synthesis. N-terminal labeling was not detectable in nerves not crushed prior to explant and incubation. Slices of embryonic day 20 visual cortex, when incubated under similar conditions as injured sciatic nerves, also showed approximately 25% of the protein incorporated [³H]Arg at the N-terminus, while arginylation was not detectable in adult rat brain slices. Since Lys is not added posttranslationally to the N-terminus, we have attempted to observe lysylation of proteins in intact cells by using cycloheximide (Cx) to block protein synthesis without interfering with protein modification. The posttranslational incorporation of Arg/Lys into proteins was found to be insensitive to up to 2.0 mM Cx in tissue extracts (in vitro). However, in intact cells, doses as low as 10 uM Cx completely inhibited the incorporation of [³H]Arg/Lys into proteins. One uM Cx allowed for some incorporation of [³H]Arg/Lys into protein and approximately 40% of the Cx insensitive Arg was incorporated into the N-terminal. These results show that in vivo but not in vitro, Cx can block protein modification, suggesting that either in intact cells protein modification requires protein synthesis, or that Cx has effects other than as an inhibitor of protein synthesis on cells in culture, effects that it does not have on the partially purified components of the reaction.