High‐throughput FTIR spectroscopy of intact HepG2 cells reveals additive and non‐additive effects of individual fatty acids when given as mixtures

In the present study we investigated the ability of high‐throughput FTIR spectroscopy in combination with multivariate data analysis to reveal if any combinatory effects of fatty acids in mixture are present in liver HepG2 cell cultures after three days of exposure. For this investigation we used an experimental mixture design containing three different octadecenoic acids (oleic acid: C18 : 1 cis‐ 9, elaidic acid: C18 : 1 trans‐ 9 and vaccenic acid: C18 : 1 trans‐ 11) of a total concentration of 100 μM. The results obtained revealed both additive and non‐additive effects of individual fatty acids when combined in mixtures. Furthermore, we demonstrate by use of scanning electron microscopy that cells are preserved as intact structures ensuring that FTIR measurements are obtained on whole cell keeping cell compounds in their natural surroundings during measurements. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Evaluating butterflies as surrogates for birds and plants in semi-natural grassland buffers

Semi-natural grasslands can support diverse faunal and floral communities, including grassland birds, beneficial insects, and native wildflowers. Monitoring biodiversity of this type of ecosystem is important to assess abundance and richness of grassland-associated species, evaluate success of establishing grasslands, and to assess overall ecosystem health. We tested butterflies as surrogates for birds and plants to assess establishment success of semi-natural grassland buffers in north-central Mississippi using Spearman rank correlation (Spearman’s ρ). Disturbance and grassland butterfly guilds were generally not suitable surrogates for grassland bird metrics, non-grassland bird metrics, or nest density metrics. Butterflies did have consistent positive correlations with plant species richness and forb metrics, as well as consistent negative correlations with grass metrics, but these correlations were generally smaller than what is considered suitable to serve as surrogates. In general, butterflies were not suitable surrogates for birds or plants in semi-natural grassland buffers.     

Carbon burial over the last four millennia is regulated by both climatic and land use change

Carbon sequestration by sediments and vegetated marine systems contributes to atmospheric carbon drawdown, but little empirical evidence is available to help separate the effects of climate change and other anthropogenic activities on carbon burial over centennial timescales. We used marine sediment organic carbon to determine the role of historic climate variability and human habitation in carbon burial over the past 5,071 years. There was centennial‐scale sensitivity of carbon supply and burial to climatic variability, with Little Ice Age cooling causing an abrupt ecosystem shift and an increase in marine carbon contributions compared to terrestrial carbon. Although land use changes during the late 1800s did not cause marked alteration in average carbon burial, they did lead to marked increases in the spatial variability of carbon burial. Thus, while carbon burial by vegetated systems is expected to increase with projected climate warming over the coming century, ecosystem restructuring caused by abrupt climate change may produce unexpected change in carbon burial whose variability is also modulated by land use change.     

Does lignin modification affect feeding preference or growth performance of insect herbivores in transgenic silver birch (<Emphasis Type="Italic">Betula pendula</Emphasis> Roth)?

Transgenic silver birch (Betula pendula Roth) lines were produced in order to modify lignin biosynthesis. These lines carry COMT (caffeate/5-hydroxyferulate O-methyltransferase) gene from Populus tremuloides driven by constitutive promoter 35S CaMV (cauliflower mosaic virus) or UbB1 (ubiquitin promoter from sunflower). The decreased syringyl/guaiacyl (S/G) ratio was found in stem and leaf lignin of 35S CaMV-PtCOMT transgenic silver birch lines when compared to non-transformed control or UbB1–PtCOMT lines. In controlled feeding experiments the leaves of transgenic birch lines as well as controls were fed to insect herbivores common in boreal environment, i.e., larvae of Aethalura punctulata, Cleora cinctaria and Trichopteryx carpinata (Lepidoptera: Geometridae) as well as the adults of birch leaf-feeding beetles Agelastica alni (Coleoptera: Chrysomelidae) and Phyllobius spp. (Coleoptera: Curculionidae). The feeding preferences of these herbivores differed in some cases among the tested birch lines, but these differences could not be directly associated to lignin modification. They could as well be explained by other characteristics of leaves, either natural or caused by transgene site effects. Growth performance of lepidopteran larvae fed on transgenic or control leaves did not differ significantly.     

Peer instruction enhanced meaningful learning: ability to solve novel problems

Students must be able to interpret, relate, and incorporate new information with existing knowledge and apply the new information to solve novel problems. Peer instruction is a cooperative learning technique that promotes critical thinking, problem solving, and decision-making skills. Therefore, we tested the hypothesis that peer instruction enhances meaningful learning or transfer, defined as the student's ability to solve novel problems or the ability to extend what has been learned in one context to new contexts. To test this hypothesis, our undergraduate exercise physiology class of 38 students was randomly divided into two groups: group A (n = 19) and group B (n = 19). A randomized crossover design in which students either answered questions individually or during peer instruction was used to control for time and order effects. The first factor that influences meaningful learning is the degree of mastery of the original material. Importantly, peer instruction significantly enhanced mastery of the original material. Furthermore, the student's ability to solve novel problems was significantly enhanced following peer instruction. Thus pausing two to three times during a 50-min class to allow peer instruction enhanced the mastery of the original material and enhanced meaningful learning, i.e., the student's ability to solve novel problems.     

A recombinant multimeric immunoglobulin expressed in rice shows assembly-dependent subcellular localization in endosperm cells

To investigate the role of subunit assembly in the intracellular deposition of multimeric recombinant proteins, we expressed a partially humanized secretory immunoglobulin in rice endosperm cells and determined the subcellular locations of the assembled protein and its individual components. Transgenic rice plants expressing either individual subunits or all the subunits of the antibody were generated by particle bombardment, and protein localization was determined by immunoelectron microscopy. Assembly of the antibody was confirmed by immunoassay and coimmunoprecipitation. Immunolocalization experiments showed no evidence for secretion of the antibody or any of its components to the apoplast. Rather, the nonassembled light chain, heavy chain and secretory component accumulated predominantly within endoplasmic reticulum-derived protein bodies, while the assembled antibody, with antigen-binding function, accumulated specifically in protein storage vacuoles. These results show that the destination of a complex recombinant protein within the plant cell is influenced by its state of assembly.     

Induction of the Nrf2-driven antioxidant response confers neuroprotection during mitochondrial stress in vivo

NF-E2 related factor (Nrf2) controls a pleiotropic cellular defense, where multiple antioxidant/detoxification pathways are up-regulated in unison. Although small molecule inducers of Nrf2 activity have been reported to protect neurons in vitro, whether similar pathways can be accessed in vivo is not known. We have investigated whether in vivo toxicity of the mitochondrial complex II inhibitor 3-nitropropionic acid (3-NP) can be attenuated by constitutive and inducible Nrf2 activity. The absence of Nrf2 function in Nrf2(-/-) mice resulted in 3-NP hypersensitivity that became apparent with time and increasing dose, causing motor deficits and striatal lesions on a more rapid time scale than identically treated Nrf2(+/+) and Nrf2(+/-) controls. Striatal succinate dehydrogenase activity, the target of 3-NP, was inhibited to the same extent in all genotypes by a single acute dose of 3-NP, suggesting that brain concentrations of 3-NP were similar. Dietary supplementation with the Nrf2 inducer tert-butylhydroquinone attenuated 3-NP toxicity in Nrf2(+/-) mice, but not Nrf2(-/-), confirming the Nrf2-specific action of the inducer in vivo. Increased Nrf2 activity alone was sufficient to protect animals from 3-NP toxicity because intrastriatal adenovirus-mediated Nrf2 overexpression significantly reduced lesion size compared with green fluorescent protein overexpressing controls. In cultured astrocytes, 3-NP was found to increase Nrf2 activity leading to antioxidant response element-dependent gene expression providing a potential mechanism for the increased sensitivity of Nrf2(-/-) animals to 3-NP toxicity in vivo. We conclude that Nrf2 may underlie a feedback system limiting oxidative load during chronic metabolic stress.     

Sphingosine kinase 1 is required for migration, proliferation and survival of MCF-7 human breast cancer cells

Sphingosine-1-phosphate (S1P) is a potent lysolipid involved in a variety of biological responses important for cancer progression. Therefore, we investigated the role of sphingosine kinase type 1 (SphK1), the enzyme that makes S1P, in the motility, growth, and chemoresistance of MCF-7 breast cancer cells. Epidermal growth factor (EGF), an important growth factor for breast cancer progression, activated and translocated SphK1 to plasma membrane. SphK1 was required for EGF-directed motility. Downregulation of SphK1 in MCF-7 cells reduced EGF- and serum-stimulated growth and enhanced sensitivity to doxorubicin, a potent chemotherapeutic agent. These results suggest that SphK1 may be critical for growth, metastasis and chemoresistance of human breast cancers.