Coral performance and bioerosion in Central Mexican Pacific reef communities

Hydrobiologia - Reef development occurs commonly under oligotrophic conditions that favor corals over competitors. In the Eastern Tropical Pacific (ETP), coral communities develop under highly...     

Plastid analysis of pigmented undifferentiated cells of marigold <Emphasis Type="Italic">Tagetes erecta</Emphasis> L. by transmission electron microscopy

Marigold (Tagetes erecta) flowers are primarily used in industry for their high pigment content. Flower color development implies that chloroplast–chromoplast transition is associated with carotenoid biosynthesis. We report the recovery of undifferentiated pigmented marigold cells, various callus tissues, and their analysis by transmission electron microscopy in order to observe accumulating pigment and development of subcellular structures. Callus was generated from leaf explants and after several rounds of recurrent selection. Green-, yellow-, and brown-colored callus were obtained that showed distinct carotenoid profiles. For green material, violaxanthin, lutein, zeaxanthin, and β-carotene were produced, while yellow callus generated mainly lutein, as did the brown callus. Chloroplast–chromoplast transition was followed by measuring plastid size and shape in undifferentiated marigold cells by digital image analysis. Cellular alterations were evident in brown callus. Chloroplasts were the main structure in green callus, while yellow callus clearly showed the formation of plastoglobules, structures that are correlated with chloroplast–chromoplast transition. The high number of plastoglobules observed in yellow callus is possibly directly related to pigment synthesis and accumulation.     

Identification of NaCl stress-responsive apoplastic proteins in rice shoot stems by 2D-DIGE

Plants have evolved sophisticated systems to cope with adverse environmental conditions such as cold, drought, and salinity. Although a number of stress response networks have been proposed, the role of plant apoplast in plant stress response has been ignored. To investigate the role of apoplastic proteins in the salt stress response, 10-day old rice plants were treated with 200mM NaCl for 1, 6 or 12h, and the soluble apoplast proteins of rice shoot stems were extracted for differential analysis, compared with untreated controls, by 2-D DIGE saturation labeling techniques. One hundred twenty-two significantly changed spots were identified by LC-MS/MS, and 117 spots representing 69 proteins have been identified. Of these proteins, 37 are apoplastic proteins according to the bioinformatic analysis. These proteins are mainly involved in the processes of carbohydrate metabolism, oxido-reduction, and protein processing and degradation. According to their functional categories and cluster analysis, a stress response model of apoplastic proteins has been proposed. These data indicate that the apoplast is important in plant stress signal reception and response.     

Mass spectrometric analysis of histone posttranslational modifications

The uses of tandem and Fourier transform mass spectrometric methodologies for assignment of the posttranslational sites and occupancies of histones and their isoforms is described employing several illustrative examples. A comparison of information that can be obtained from intact protein sequencing and proteolytic digestion is presented.     

Neurotransmitter release regulated by a MALS-liprin-alpha presynaptic complex

Synapses are highly specialized intercellular junctions organized by adhesive and scaffolding molecules that align presynaptic vesicular release with postsynaptic neurotransmitter receptors. The MALS/Veli-CASK-Mint-1 complex of PDZ proteins occurs on both sides of the synapse and has the potential to link transsynaptic adhesion molecules to the cytoskeleton. In this study, we purified the MALS protein complex from brain and found liprin-alpha as a major component. Liprin proteins organize the presynaptic active zone and regulate neurotransmitter release. Fittingly, mutant mice lacking all three MALS isoforms died perinatally with difficulty breathing and impaired excitatory synaptic transmission. Excitatory postsynaptic currents were dramatically reduced in autaptic cultures from MALS triple knockout mice due to a presynaptic deficit in vesicle cycling. These findings are consistent with a model whereby the MALS-CASK-liprin-alpha complex recruits components of the synaptic release machinery to adhesive proteins of the active zone.     

Caspase-3 inhibits the growth of breast cancer cells independent of protease activity

In this study, the MCF-7 breast cancer cells that lack caspase-3 were transfected with a wild type (WT) or mutant caspase-3 cDNA. Expression of the WT, but not of the mutant, caspase-3 was associated with increased caspase activity and susceptibility to staurosporine (STS)-induced apoptosis. Both derivatives displayed inhibition of cell growth compared with vector control cells. Growth inhibition was associated with increased expression of the cyclin dependent kinase (CDK) inhibitor p27Kip1 in the WT, but not in the mutant caspase-3 expressing cells. Cyclin D1 expression level was not affected by caspase-3 expression. Phosphorylation of the Akt protein was decreased in both WT and mutant caspase transfected cells, although Akt expression level remained unchanged. These results suggest that caspase-3 might have biological functions independent of its protease activity and that its loss might contribute to tumor development by increasing the growth potential of cancer cells.