Ozone stress‐induced proteomic changes in leaf total soluble and chloroplast proteins of soybean reveal that carbon allocation is involved in adaptation in the early developmental stage

Considerable soybean yield losses caused by ozone (O₃) stress have been demonstrated by large‐scale meta‐analyses of free‐gas concentration enrichment systems. In this study, comparative proteomic approach was employed to explore the differential changes of proteins in O₃ target structures such as leaf and chloroplasts of soybean seedlings. Acute O₃ exposure (120 parts‐per‐billion) for 3 days did not cause any visible symptoms in developing leaves. However, higher amounts of ROS and lipid peroxidation indicated that severe oxidative burst occurred. Immunoblot analysis of O₃‐induced known proteins revealed that proteins were modulated before symptoms became visible. Proteomic analysis identified a total of 20 and 32 differentially expressed proteins from O₃‐treated leaf and chloroplast, respectively. Proteins associated with photosynthesis, including photosystem I/II and carbon assimilation decreased following exposure to O₃. In contrast, proteins involved in antioxidant defense and carbon metabolism increased. The activity of enzymes involved in carbohydrate metabolism increased following exposure to O₃, which is consistent with the decrease in starch and increase in sucrose concentrations. Taken together, these results suggest that carbon allocation is tightly programmed, and starch degradation probably feeds the tricarboxylic acid cycle while the photosynthesis pathway is severely affected during O₃ stress.     

Comparative analyses of the proteomes of leaves and flowers at various stages of development reveal organ‐specific functional differentiation of proteins in soybean

The functional differentiation of protein networks in individual organs and tissues of soybean at various developmental stages was investigated by proteomic approach. Protein extraction by Mg/NP‐40 buffer followed by alkaline phenol‐based method was optimized for proteomic analysis. Proteome analyses of leaves at various developmental stages showed 26 differentially expressed proteins, wherein proteins in translocon at the outer/inner envelope membrane of chloroplast protein‐transport machineries increased significantly at the first trifoliate. Immunoblot analysis showed chaperonin‐60 expressed abundantly in young leaves, whereas HSP 70 and ATP‐synthase β were constitutively expressed in all tissues. The net photosynthesis rate and chlorophyll content showed an age‐dependent correlation in leaves. These results suggest that proteins involved in carbon assimilation, folding and assembly, and energy may work synchronously and show a linear correlation to photosynthesis at developmental stages of leaves. Comparison of flower bud and flower proteome reveals 29 differentially expressed proteins, wherein proteins involved in mitochondrial protein transport and assembly, secondary metabolism, and pollen‐tube growth were up‐regulated during flower development. Together, these results suggest that during developmental stages, each type of tissue is associated with a specific group of proteins; wherein proteins involved in energy, sugar metabolism, and folding, assembly, and destination may play pivotal roles in the maturation process of each organ or tissue.     

Cassava, Manihot esculenta Crantz, genetic resources: origin of the crop, its evolution and relationships with wild relatives

About 98 species of Manihot are known. All of them are native to the New World and are concentrated in four regions in Brazil and Central America. All the Manihot species so far examined have 2n = 36 chromosomes. Interspecific hybrids between cassava and its wild relatives show relatively normal meiosis, and further generations can be obtained. Electrophoresis shows affinity among wild species of different sections, and between some of them and cassava. Both polyploidy and apomixis may have contributed to speciation in this genus. Polyploidy produced genetic variability, while apomixis is responsible for perpetuating new hybrid types adapted to different environments. Cassava may have originated by hybridization between two wild Manihot species, followed by vegetative reproduction of the hybrid.     

Microsatellite markers confirm high apomixis level in cassava bred clones

Apomixis genes have successfully been transferred to cassava by hybridization with the wild species, Manihot glaziovii. The interspecific hybrid of cassava and M. glaziovii was left for open pollination during the subsequent three generations. Seven sibs and their maternal progenitor of the fourth generation were genotyped using five microsatellite loci previously developed for cassava. All sibs were identical with each other and with their maternal progenitor. Sibs from M. glaziovii itself proved to be identical when examined by the same microsatellite loci. These results lead to the conclusion that apomixis do occur in wild cassava relatives and apparently has played an important role in Manihot speciation.     

Fibroblasts Mobilize Tumor Cell Glycogen to Promote Proliferation and Metastasis

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Comparative proteomic analysis of bacterial wilt susceptible and resistant tomato cultivars

To investigate the molecular mechanisms of bacterial resistance in susceptible and resistant cultivars of tomato, a proteomic approach was adopted. Four cultivars of tomato were selected on the basis of their response to bacterial (Pseudomonas solanacearum) inoculation wherein cultivar Roma and Riogarande, and cultivar Pusa Ruby and Pant Bahr were considered as resistant and susceptible cultivars, respectively. Proteins were extracted from leaves of 3-week-old seedlings of the four cultivars and separated by 2-DE. A total of nine proteins were found to be differentially expressed between the susceptible and resistant cultivars. Amino acid sequences of these proteins were determined with a protein sequencer. The identified proteins belongs to the categories of energy, protein destination and storage, and defense. Of these proteins, a 60 kDa chaperonin and an apical membrane antigen were significantly upregulated in resistant cultivars compared with susceptible cultivars. Application of jasmonic acid and salicylic acid resulted in significant changes in levels of apical membrane antigen and protein disulfide-isomerase. Taken together, these results suggest that apical membrane antigen might be involved in bacterial resistance process through salicylic acid induced defense mechanism signaling in tomato plants.     

Mesopelagic microbial carbon production correlates with diversity across different marine particle fractions

The vertical flux of marine snow particles significantly reduces atmospheric carbon dioxide concentration. In the mesopelagic zone, a large proportion of the organic carbon carried by sinking particles dissipates thereby escaping long term sequestration. Particle associated prokaryotes are largely responsible for such organic carbon loss. However, links between this important ecosystem flux and ecological processes such as community development of prokaryotes on different particle fractions (sinking vs. non-sinking) are yet virtually unknown. This prevents accurate predictions of mesopelagic organic carbon loss in response to changing ocean dynamics. Using combined measurements of prokaryotic heterotrophic production rates and species richness in the North Atlantic, we reveal that carbon loss rates and associated microbial richness are drastically different with particle fractions. Our results demonstrate a strong negative correlation between prokaryotic carbon losses and species richness. Such a trend may be related to prokaryotes detaching from fast-sinking particles constantly enriching non-sinking associated communities in the mesopelagic zone. Existing global scale data suggest this negative correlation is a widespread feature of mesopelagic microbes.Subject terms: Microbial ecology, Biogeochemistry