Mechanism of the light state transition in photosynthesis. II. Analysis of phosphorylated polypeptides in the red alga,Porphyridium cruentum

The possible involvement of a reversible protein phosphorylation event in the regulation of excitation energy distribution was studied in the red alga Porphyridium cruentum. Whole cells were incubated in phosphate-depleted growth medium containing carrier-free [³²P]orthophosphate for several hours to label the intracellular phosphate pools, and they were then converted to State 1 or State 2 by illumination using blue or green light, respectively. The successful transition to State 1 or State 2 was verified by 77 K fluorescence spectroscopy of the chlorophyll emission and the cells were then denatured using either acetone, trichloroacetic acid or boiling detergent. The whole cell lysates were solubilized, treated with RNAase, and analyzed for phosphoproteins by SDS-polyacrylamide gel electrophoresis. At least twelve polypeptides were found to be phosphorylated but no changes in specific radioactivity of the polypeptides were detected when samples from cells in State 1 and State 2 were compared. We conclude that a reversible protein phosphorylation event is not implicated in the state transition in P. cruentum. A model is presented for the mechanism of the light state transition in organisms that contain phycobilisomes which is different from the mechanism of energy distribution proposed for higher plants.     

Development and application of an analytical approach to assess an antibody's potential for disulfide reduction

Monoclonal antibody (mAb) interchain disulfide bond reduction has been observed in a recent large-scale clinical manufacturing operation. A massive reduction/precipitation at post-clarification steps has occurred. This note presents the development of a novel analytical approach to identify the “potential reduction”—a unique approach to predict the propensity of a monomeric-profiled mAb to be reduced in the post-harvest stage, such as harvest clarification and/or purification steps. The core of this new approach includes comparing the non-reducing capillary electrophoresis profiles of pre- and post-vacuum treated mAb in harvest cell culture fluid (HCCF). Using this approach, the potential reductions of two in-house mAbs in the unclarified and clarified cell culture harvest were assessed.     

Redox ratio in the left ventricle of the growth restricted fetus is positively correlated with cardiac output

Intrauterine growth restriction (IUGR) is a result of limited substrate supply to the developing fetus in utero, and can be caused by either placental, genetic or environmental factors. Babies born IUGR can have poor long-term health outcomes, including being at higher risk of developing cardiovascular disease. Limited substrate supply in the IUGR fetus not only changes the structure of the heart but may also affect metabolism and function of the developing heart. We have utilised two imaging modalities, two-photon microscopy and phase-contrast MRI (PC-MRI), to assess alterations in cardiac metabolism and function using a sheep model of IUGR. Two-photon imaging revealed that the left ventricle of IUGR fetuses (at 140–141 d GA) had a reduced optical redox ratio, suggesting a reliance on glycolysis for ATP production. Concurrently, the use of PC-MRI to measure foetal left ventricular cardiac output (LVCO) revealed a positive correlation between LVCO and redox ratio in IUGR, but not control fetuses. These data suggest that altered heart metabolism in IUGR fetuses is indicative of reduced cardiac output, which may contribute to poor cardiac outcomes in adulthood.     

Internal recycling of respired CO2 may be important for plant functioning under changing climate regimes

Recent studies have provided evidence of a large flux of root-respired CO₂ in the transpiration stream of trees. In our study, we investigated the potential impact of this internal CO₂ transport on aboveground carbon assimilation and CO₂ efflux. To trace the transport of root-respired CO₂, we infused a ¹³C label at the stem base of field-grown Populus deltoides Bartr. ex. Marsh trees. The ¹³C label was transported to the top of the stem and throughout the crown via the transpiration stream. Up to 17% of the ¹³C label was assimilated by chlorophyll-containing tissues. Our results provide evidence of a mechanism for recycling respired CO₂ within trees. Such a mechanism may have important implications for how plants cope with predicted increases in intensity and frequency of droughts. Here, we speculate on the potential significance of this recycling mechanism within the context of plant responses to climate change and plants currently inhabiting arid environments.     

A MOD(ern) perspective on literature curation

Curation of biological data is a multi-faceted task whose goal is to create a structured, comprehensive, integrated, and accurate resource of current biological knowledge. These structured data facilitate the work of the scientific community by providing knowledge about genes or genomes and by generating validated connections between the data that yield new information and stimulate new research approaches. For the model organism databases (MODs), an important source of data is research publications. Every published paper containing experimental information about a particular model organism is a candidate for curation. All such papers are examined carefully by curators for relevant information. Here, four curators from different MODs describe the literature curation process and highlight approaches taken by the four MODs to address: (1) the decision process by which papers are selected, and (2) the identification and prioritization of the data contained in the paper. We will highlight some of the challenges that MOD biocurators face, and point to ways in which researchers and publishers can support the work of biocurators and the value of such support.     

Adult body growth and reproductive investment vary markedly within and across Atlantic and Pacific herring: a meta-analysis and review of 26 stocks

Reviews in Fish Biology and Fisheries - Life-history traits of Pacific (Clupea pallasii) and Atlantic (Clupea harengus) herring, comprising both local and oceanic stocks subdivided into...