Ethanol and acetate production by <Emphasis Type="Italic">Clostridium ljungdahlii</Emphasis> and <Emphasis Type="Italic">Clostridium autoethanogenum</Emphasis> using resting cells

Combined gasification and fermentation technologies can potentially produce biofuels from renewable biomass. Gasification generates synthesis gas consisting primarily of CO, CO₂, H₂, N₂, with smaller amounts of CH₄, NO_x, O₂, C₂ compounds, ash and tars. Several anaerobic bacteria species can ferment bottled mixtures of pure synthesis gas constituents. However, there are challenges to maintaining culture viability of synthesis gas exposed cells. This study was designed to enhance culture stability and improve ethanol-to-acetate ratios using resting (non-growing) cells in synthesis gas fermentation. Resting cell states were induced in autotrophic Clostridium ljungdahlii cultures with minimal ethanol and acetate production due to low metabolic activity compared to growing cell production levels of 5.2 and 40.1 mM of ethanol and acetate. Clostridium autoethanogenum cultures were not induced into true resting states but did show improvement in total ethanol production (from 5.1 mM in growing cultures to 9.4 in one nitrogen-limited medium) as well as increased shifts in ethanol-to-acetate production ratios.     

Interactions between fungal growth,substrate utilization,and enzyme production during solid substrate cultivation of Phanerochaete chrysosporium on cotton stalks

Fungal pretreatment, using lignin-degrading microorganisms to improve lignocellulosic feedstocks with minimal energy input, is a potential alternative to physiochemical pretreatment methods. Identifying the kinetics for fungal pretreatment during solid substrate cultivation is needed to help establish the processing conditions for effective scale up of this technology. In this study, a set of mathematical models were proposed for describing the interactions between holocellulose consumption, lignin degradation, cellulase, ligninolytic enzyme, and the growth of Phanerochaete chrysosporium during a 14 day fungal pretreatment process. Model parameters were estimated and validated by the System Biology Toolbox in MatLab. Developed models provided sufficiently accurate predictions for fungal growth (R ² = 0.97), holocellulose consumption (R ² = 0.97), lignin degradation (R ² = 0.93) and ligninolytic enzyme production (R ² = 0.92), and fair prediction for cellulase production (R ² = 0.61). The models provide valuable information for understanding the interactive mechanisms in biological systems as well as for fungal pretreatment process scale up and improvement.     

Hawai‘i’s Mountain-to-Sea Ecosystems: Social–Ecological Microcosms for Sustainability Science and Practice

There is an urgent need to develop the underlying theory and principles of “sustainability science,” based on an understanding of the fundamental interactions between nature and humans. This requires a new research and education paradigm that embraces biocomplexity, integrates the physical, biological, and social sciences, and uses a coupled, human–natural systems approach. An initiative aligned with this paradigm and approach, and centered on the Hawaiian Island’s unique mountain-to-sea ecosystems, is developing at the University of Hawai‘i. These ecosystems, extending from upland tropical forests to the fringing coral reefs, correspond to the roughly wedge-shaped catchments, traditionally called ahupua‘a in the Hawaiian language. Despite the collapse of the ahupua‘a system and, tragically, the Native Hawaiian population, its legacy of ecological and cultural stewardship remains. This legacy, and the potential of these ecosystems as microcosms for addressing the core questions of sustainability science, has provided the impetus for a growing number of projects employing a social–ecological systems perspective. An overview of three projects that employ a “learning community” approach and cultural stewardship perspective inspired by the ahupua‘a system is provided. These include the Ecosystems Thrust Area of Hawai‘i EPSCoR, a U.S. National Science Foundation research infrastructure program, focused on ecosystem research and monitoring activities; a sustainability curriculum program, Mālama I Ka ‘Āina, of the College of Education; and a project that builds on programs of the Division of Ecology and Health and its affiliated Asia-Pacific Center for Infectious Disease Ecology, linking ecosystem resilience and infectious diseases.     

Adult stem cells and bioengineering strategies for the treatment of cerebral ischemic stroke

The adult central nervous system (CNS) contains a population of neural stem cells, yet unlike many other tissues, has a very limited capacity for self-repair. Promoting tissue repair and functional recovery following CNS injury or disease is a high priority as there are currently no effective treatments towards this end for the treatment of disorders such as stroke, traumatic brain injury and spinal cord injury. Recent advances in stem cell biology have offered a number of enticing potential avenues and we will discuss these possibilities along with the associated challenges as they pertain to stroke. We will consider exogenous therapies involving the transplantation of adult stem cells, and the mobilization of endogenous stem cells, as well as drug delivery and tissue engineering strategies that enhance and complement the cell based strategies.     

Identification of a gene family regulated by transforming growth factor-beta

We have identified two related genes whose mRNAs are increased after treatment with transforming growth factor-beta (TGF-beta 1). Mouse AKR-2B cells were treated with TGF-beta 1 in the presence of cyclohexamide and a cDNA library was subjected to differential screening. Several TGF-beta-induced genes (beta IG) were isolated and two of these, beta IG-M1 and beta IG-M2, were characterized. beta IG-M1 and beta IG-M2 RNAs were significantly increased after TGF-beta 1 treatment and both were superinduced in the presence of cyclohexamide. cDNA sequence analysis of beta IG-M1 showed that it encoded a 379-amino-acid protein which was 81% homologous to CEF-10, a v-src and TPA-inducible gene, and identical to cyr61, a gene induced by serum in growth-arrested BALB-3T3 cells. cDNA sequence analysis of beta IG-M2 showed that it encoded a 348-amino-acid protein that was 50% homologous to beta IG-M1. Thirty-eight cysteine residues are conserved between beta IG-M1 and beta IG-M2, which are clustered at the amino and carboxy ends: The middle regions of the two proteins are cysteine free and display the highest degree of nonhomology. Both proteins contain an amino-terminal cysteine-rich motif common to insulin-like growth factor binding proteins and a carboxy-terminal domain with strong homology to a motif found near the carboxy-terminal of the malarial circumsporozoite protein which may be involved in cell adhesion. The regulation of mRNA encoding these proteins by TGF-beta 1 suggests that they may be involved in mediating some of the pleiotropic effects of this multipotent modulator of cell growth and differentiation.     

A qualitative and quantitative study of the cellular fatty acids of 'Streptococcus milleri' with capillary gas chromatography

Fatty acid analysis was done with GC and GC-MS on 21 strains of 'Streptococcus milleri', representative of the various proposed species. Although no qualitative differences were found in the fatty acid profiles, discriminant analysis of the quantitative data revealed three groups. Streptococcus anginosus and Streptococcus constellatus were indistinguishable but separated from the other two groups which comprised Streptococcus intermedius, with a wide fermentation pattern and Streptococcus intermedius with a narrow fermentation pattern. Three of the strains could be distinguished from the others by a 'fingerprint' of a particularly prominent fatty acid peak. The results support the suggestion that there is more than one species in this group of organisms and that the technique might be of value in epidemiological investigations of 'S. milleri'.     

Light-evoked depolarizations in the retina ofStrombus: Role of calcium and other divalent cations

Previous studies indicate that overlapping inward sodium and outward potassium currents play a role in generating the waveform of light-evoked depolarizations (LEDs) in one type of retinal neuron in Strombus luhuanus, a marine gastropod [Chinn, K. S., and Gillary, H. L. (1985). Comp. Biochem. Physiol. 80A:233-245]. This paper concerns the effects of divalent cations on the LED. The LED can exhibit a distinct early phase of depolarization (DE). Increasing the [Ca2+] in the artificial seawater (ASW) bathing medium reduced the amplitude of the entire LED, and omitting Ca2+ increased it. Adding 10 mM Sr2+ or 10 mM Mn2+ to either normal ASW or 0-Ca2+ ASW decreased the LED amplitude. Adding 10 mM Ba2+ to 0-Ca2+ ASW also decreased the LED amplitude, but adding Ba2+ to normal ASW selectively increased DE. Cd2+ (100 microM) selectively reduced DE when added to normal ASW but not when added to 0-Ca2+ ASW. The results show that a variety of divalent cations can alter the currents that underlie the LED. They also suggest that an inward Ca2+ current occurs during DE.     

Embryonic cortical neural stem cells migrate ventrally and persist as postnatal striatal stem cells

Embryonic cortical neural stem cells apparently have a transient existence, as they do not persist in the adult cortex. We sought to determine the fate of embryonic cortical stem cells by following Emx1(IREScre); LacZ/EGFP double-transgenic murine cells from midgestation into adulthood. Lineage tracing in combination with direct cell labeling and time-lapse video microscopy demonstrated that Emx1-lineage embryonic cortical stem cells migrate ventrally into the striatal germinal zone (GZ) perinatally and intermingle with striatal stem cells. Upon integration into the striatal GZ, cortical stem cells down-regulate Emx1 and up-regulate Dlx2, which is a homeobox gene characteristic of the developing striatum and striatal neural stem cells. This demonstrates the existence of a novel dorsal-to-ventral migration of neural stem cells in the perinatal forebrain.