Alumina-doped alginate gel as a cell carrier for ethanol production in a packed-bed bioreactor

Alumina-doped alginate gel (AEC) was developed as a new type of cell carrier to be used in ethanol fermentation. The presence of the alumina particles in alginate gel not only improved the porous structure of the carrier, but also provided many advantageous characteristics including good mechanical strength, high stability, and high immobilization yield. The attachment of alumina particles and yeast cells by electrostatic attraction was shown to promote cell growth and increase ethanol productivity. The AEC carrier was found to be more effective for the immobilization of Saccharomyces cerevisiae M30 than the conventional Ca-alginate bead. Ethanol productivities of 1.4 and 7.9 ∼ 12.6 g/(L/h) were obtained using the AEC cultures in batch and continuous modes of operation, respectively, with an ethanol yield of 43.9 ∼ 46.7% and an immobilized yield of 81.4 ∼ 84.5%. Ethanol fermentation in a continuous packed-bed reactor using the AEC carrier was stable for > 30 days.     

Optimization of expression,purification, and NMR measurement for structural studies of transmembrane region of amyloid β protein

The amyloid precursor protein (APP) is an integral transmembrane protein which has been suggested to play a central role in the pathogenesis of Alzheimer’s disease. Despite the enormous amount of research conducted on amyloid protein, the precise mechanism of its toxic effect is not yet fully understood. To better understand the mechanism and function of amyloid protein, it is critical to elucidate the three-dimensional structure of the single transmembrane spanning region of human APP (hAPP-TM). Unfortunately, it is difficult to prepare the peptide sample because hAPP-TM is a membrane-bound protein that transverses the lipid bilayer of the cell membrane. Generally, the preparation of a transmembrane peptide is very difficult and time-consuming. In fact, high yield production of transmembrane peptides has been limited by experimental difficulties related to insufficient yields and the low solubility of such peptides. In this study, we describe experimental processes developed to optimize the expression, purification, and NMR measurement conditions for hAPP-TM transmembrane peptide.     

Electrocoagulation as a clarifiation and pre-purification step in plant based bioprocesses

Electrocoagulation is a technique that has been applied to water and wastewater treatment. We propose here extension of this technique to the field of plant downstream processing (DSP), where plants are used as a bioreactors for recombinant protein production. The main problem in plant-based bioreactors is the presence of chlorophyll and phenolic compounds in plant extracts, which tend to precipitate and denature proteins. Their removal from the extracts is essential, since they have a large impact on the DSP performance. In the present work we studied the application of an electrocoagulation based technique to clarify tobacco leaf extracts by removing chlorophyll and phenolic compounds. By manipulating the pH of electrocoagulation, 90% of chlorophyll, 65% of phenolic compounds, and only 23% of total protein were removed from the extract. The process preferentially removes proteins with more acidic pI (below 6.03) and the pH of the process differentially effects removal of acidic and basic proteins.     

Conversion of AFLP markers to high-throughput markers in a complex polyploid,sugarcane

The application of DNA markers linked to traits of commercial value in sugarcane may increase the efficiency of sugarcane breeding. The majority of markers generated for quantitative trait locus mapping in sugarcane have been single sequence repeats or AFLPs (amplified fragment length polymorphisms). Since AFLP markers are not adapted for large-scale implementation in plant breeding, our objective was to assess the feasibility of converting AFLP markers to fast, cheap and reliable PCR-based assays in a complex polyploid, sugarcane. Three AFLP markers were selected on the basis of an association to resistance to the fungal pathogen Ustilago scitaminea, the causal agent of smut in sugarcane. We developed an approach which enabled the identification of polymorphisms in these AFLP markers. Towards this goal, we employed GenomeWalking and 454 sequencing to isolate sequences adjacent to the linked AFLP markers and identify SNP (single nucleotide polymorphisms) haplotypes present in the homo(eo)logous chromosomes of sugarcane. One AFLP marker was converted to a cleavage amplified polymorphic sequence marker, another to a SCAR (sequence characteristered amplified region) marker and the final AFLP marker to a SNP PCR-based assay. However, validation of each of the markers in 240 genotypes resulted in 99, 90 and 60% correspondence with the original AFLP marker. These experiments indicate that even in a complex polyploid such as sugarcane, polymorphisms identified by AFLP can be converted to high-throughput marker systems, but due to the complexity this would only be carried out for high-value markers. In some cases, the polymorphisms identified are not transferable to more sequence-specific PCR applications.     

Mechanism of the plant community succession process in the Zhenjiang Waterfront Wetland

In this study, replacement of dominant populations (Phragmites australis and Phalaris arundinacea) in the plant community succession process in the Zhenjiang Waterfront Wetland was approached from three aspects: growth, photosynthesis, and specific competitive characteristics. The productivity of Phragmites, based on intrinsic rate of increase and environmental carrying capacity of the several chosen growth indices (plant length, sheath height, and biomass), was significantly higher than that of Phalaris. Phragmites had a higher photosynthetic rate than Phalaris. However, Phalaris had a markedly lower light compensation point, which suggested that it was capable of better utilization of weak light. This possibly might account for its survival beneath Phragmites. At three different coverage gradients, the relative yield total was greater than 1, indicating a certain degree of complementary resource utilization via niche separation between both species. Significant differences in the competition ratio of both species indicated a superiority of Phragmites over Phalaris in terms of competitive capability. Thus, the Phragmites population tended to exclude the Phalaris population and became the mono-dominant population in the community succession process. For Phalaris, traits such as its better utilization of weak light, its complementary resource utilization, and a partial separation of growth period compared to Phragmites prevented complete replacement of its population to some degree. In this particular study area in the Zhenjiang Waterfront Wetland, the hydrological conditions of the river beach determined by its elevation possibly acted as the dominant regulator of the plant succession process.     

Ecology of <Emphasis Type=Italic>Harmonia axyridis</Emphasis> in natural habitats within its native range

Originally distributed in northeast Asia, Harmonia axyridis (Coleoptera: Coccinellidae) is now found throughout much of the temperate zone. In its native area, H. axyridis maintains stable populations in heterogeneous and temporary habitats because of its great ability to find prey and reproduce, coupled with density-dependent and self-regulatory population regulation. A negative correlation of H. axyridis on the biodiversity of the aphidophagous community has been observed in its native range. The decrease in biodiversity may be mainly caused by the wider range of habitats available to H. axyridis than to the coexisting species. From a theoretical perspective, density-dependent regulation of H. axyridis populations, e.g., cannibalism, may be more important in maintaining the H. axyridis-dominated system, probably than is intraguild predation. Habitat heterogeneity may also be important to the coexistence of H. axyridis and other predators in both native and invaded areas.     

Analysis of the causes of declines in Western Siberian outbreaks of the nun moth <Emphasis Type=Italic>Lymantria monacha</Emphasis>

This study presents the results of an investigation into the causal factors of precipitous population declines after five mass outbreaks of nun moths (Lymantria monacha) in territories of Western Siberian (Novosibirsk and Tyumen oblasts, Russia). Nucleopolyhedrovirus (NPV) and parasitoids represented by the families Tachinidae and Sarcophagidae (Diptera) were found to be major contributors to the degradation of these outbreaks. Viable occlusion bodies persisted on pine needles during a two-year observation period and contaminated nun moth eggs, resulting in the death of the insects from NPV infection. A high probability of insect/virus contacts was largely attributable to the poor flying ability of female moths. Moreover, a latent virus was apparently activated in part of the insect population due to asynchrony between the growth rate of larvae and pine phenology.