Growth, viral production and metabolism of a Helicoverpa zea cell line in serum-free culture

Insect cell cultures have been extensively utilised for means of production for heterologous proteins and biopesticides. Spodoptera frugiperda (Sf9) and Trichoplusia ni (High Five(TM)) cell lines have been widely used for the production of recombinant proteins, thus metabolism of these cell lines have been investigated thoroughly over recent years. The Helicoverpa zea cell line has potential use for the production of a biopesticide, specifically the Helicoverpa armigera single-nucleocapsid nucleopolyhedrovirus (HaSNPV). The growth, virus production, nutrient consumption and waste production of this cell line was investigated under serum-free culture conditions, using SF900II and a low cost medium prototype (LCM). The cell growth ( growth rates and population doubling time) was comparable in SF900II and LCM, however, lower biomass and cell specific virus yields were obtained in LCM. H. zea cells showed a preference for asparagine over glutamine, similar to the High Five(TM) cells. Ammonia was accumulated to significantly high levels (16 mM) in SF900II, which is an asparagine and glutamine rich medium. However, given the absence of asparagine and glutamine in the medium ( LCM), H. zea cells adapted and grew well in the absence of these substrates and no accumulation of ammonia was observed. The adverse effect of ammonia on H. zea cells is unknown since good production of biologically active HaSNPV was achieved in the presence of high ammonia levels. H. zea cells showed a preference for maltose even given an abundance supply of free glucose. Accumulation of lactate was observed in H. zea cell cultures.

Regulation of adult olfactory neurogenesis by insulin-like growth factor-I

Insulin-like growth factor-I (IGF-I) has multiple effects within the developing nervous system but its role in neurogenesis in the adult nervous system is less clear. The adult olfactory mucosa is a site of continuing neurogenesis that expresses IGF-I, its receptor and its binding proteins. The aim of the present study was to investigate the roles of IGF-I in regulating proliferation and differentiation in the olfactory mucosa. The action of IGF-I was assayed in serum-free culture combined with bromodeoxyuridine-labelling of proliferating cells and immunochemistry for specific cell types. IGF-I and its receptor were expressed by globose basal cells (the neuronal precursor) and by olfactory neurons. IGF-I reduced the numbers of proliferating neuronal precursors, induced their differentiation into neurons and promoted morphological differentiation of neurons. The evidence suggests that IGF-I is an autocrine and/or paracrine signal that induces neuronal precursors to differentiate into olfactory sensory neurons. These effects appear to be similar to the cellular effects of IGF-I in the developing nervous system.

Neural Stem cell Isolation and Characterization

Throughout the process of development and continuing into adulthood, stem cells function as a reservoir of undifferentiated cell types, whose role is to underpin cell genesis in a variety of tissues and organs. In the adult, they play an essential homeostatic role by replacing differentiated tissue cells "worn off" by physiological turnover or lost to injury or disease. As such, the discovery of such cells in the adult mammalian central nervous system (CNS), an organ traditionally thought to have little or no regenerative capacity, was most unexpected. Nonetheless, by employing a novel serum-free culture system termed the neurosphere assay, Reynolds and Weiss demonstrated the presence of neural stem cells in both the adult (Reynolds and Weiss, 1992) and embryonic mouse brain (Reynolds et al., 1992). Here we describe how to generate, serially passage, and differentiate neurospheres derived from both the developing and adult brain, and provide more technical details that will enable one to achieve reproducible cultures, which can be passaged over an extended period of time.

Effect of free ammonia and free nitrous acid concentration on the anabolic and catabolic processes of an enriched Nitrosomonas culture

The effects of free ammonia (FA; NH3) and free nitrous acid (FNA; HNO2) concentrations on the metabolisms of an enriched ammonia oxidizing bacteria (AOB) culture were investigated using a method allowing the decoupling of growth and energy generation processes. A lab-scale sequencing batch reactor (SBR) was operated for the enrichment of an AOB culture. Fluorescent in-situ hybridization (FISH) analysis showed that 82% of the bacterial population in the SBR bound to the NEU probe specifically designed for Nitrosomonas europaea. Batch tests were carried out to measure the oxygen and ammonium consumption rates by the culture at various FA and FNA levels, in the presence or absence of inorganic carbon (CO2, HCO3, and CO32-). It was revealed that FA of up to 16.0 mgNH(3)-N (.) L-1, which was the highest concentration used in this study, did not have any inhibitory effect on either the catabolic or anabolic processes of the Nitrosomonas culture. In contrast, FNA inhibited both the growth and energy production capabilities of the Nitrosomonas culture. The inhibition on growth initiated at approximately 0.10 mgHNO(2)-(NL-1)-L-., and the data suggested that the biosynthesis was completely stopped at an FNA concentration of 0.40 mgHNO(2)-N (.) L-1. The inhibition on energy generation initiated at a slightly lower level but the Nitrosomonas culture was still oxidizing ammonia at half of the maximum rate at an FNA concentration of 0.50-0.63 mgHNO(2)-N (.) L-1. The affinity constant of the Nitrosomonas culture with respect to ammonia was determined to be 0.36 mgNH3-N (.) L-1, independent of the presence or absence of inorganic carbon. (c) 2006 Wiley Periodicals, Inc.

The inhibitory effects of free nitrous acid on the energy generation and growth processes of an enriched Nitrobacter culture

The inhibitory effects of nitrite (NO2-)/free nitrous acid (HNO2-FNA) on the metabolism of Nitrobacter were investigated using a method allowing the decoupling of the growth and energy generation processes. A lab-scale sequencing batch reactor was operated for the enrichment of a Nitrobacter culture. Fluorescent in situ hybridization (FISH) analysis showed that 73% of the bacterial population was Nitrobacter. Batch tests were carried out to assess the oxygen and nitrite consumption rates of the enriched culture at low and high nitrite levels, in the presence or absence of inorganic carbon. It was observed that in the absence of CO2, the Nitrobacter culture was able to oxidize nitrite at a rate that is 76% of that in the presence of CO2, with an oxygen consumption rate that is 85% of that measured in the presence of CO2. This enabled the impacts of nitrite/FNA on the catabolic and anabolic processes of Nitrobacter to be assessed separately. FNA rather than nitrite was likely the actual inhibitor to the Nitrobacter metabolism. It was revealed that FNA of up to 0.05 mg HNO2-N center dot L-1 (3.4 mu M), which was the highest FNA concentration used in this study, did not have any inhibitory effect on the catabolic processes of Nitrobacter. However, FNA initiated its inhibition to the anabolic processes of Nitrobacter at approximately 0.011 mg HNO2-N center dot L-1 (0.8 mu M), and completely stopped biomass synthesis at a concentration of approximately 0.023 mg HNO2-N center dot L-1 (1.6 mu M). The inhibitory effect could be described by an empirical inhibitory model proposed in this paper, but the underlying mechanisms remain to be revealed.

Campfire culture and computer culture: Museums of the present

In Australia indigenous peoples have never had a treaty with the dominant cultures; and their on-going marginalisation is some testimony to this. However, they have not languished entirely in a policy free environment: media is one area where some policy advances have been made; but media policy development has experienced a number of problems. It has tended to be monolithic in a situation demanding multi and complex treatments. And funding, as always, never seems sufficient to meet those multi and complex needs. This paper examines a small remote community on the island of Milingimbi off the northern coast of Arnhem Land in Australia's far north. People in East Arnhem Land refer to themselves collectively as Yolngu. This community is not typical of many documented cases of media relations between indigenous and non-indigenous peoples; however, the fact that it tends to overturn much of the conventional scholarship surrounding indigenous peoples and the media, helps shed new light on the inadequacy of not only monolithic media policy, but the inadequacy of media-only approaches to policy. Arguably, the significance of the media in Milingimbi is part of a 'triangulated' relationship between indigenous and dominant cultures. That triangulation also involves appropriate forms of government and education, which coupled with appropriate media appear to offer new ways of seeing self-government alongside relative cultural and economic autonomy.