Face Starvation Research Articles

Food Donation Application: Software Development Life Cycle Case Study

Abstract: Many people face starvation because of food shortages. Food shortages in developing countries are common. Smallholders and laborers are the most affected. In addition, in the current pandemic, laborers' employment has been taken away, leaving them unable to feed themselves and their families. There are several ways and means to help the needy, but nothing works better than making a contribution to an organization dedicated to helping poor communities battle against poverty. People living in NGOs also face food shortage issues. This application can help needy people eat food. With the help of this application, restaurants can serve food to many people.

Food Insecurity, Population Health and Food Supply Chain: A Framework Integrating Three Constructs

Design/methodology/approach: food insecurity is discussed within population health and food supply chain framework. Research shows that food insecurity is one of the three main causes in impacting population health. After exploring the relationship between food insecurity and population health, this study explores possible solutions to address food insecurity through food supply chain management framework. Food supply chain is different from commercial supply chain in many important attributes. Literature does not provide research framework linking these three attributes (food insecurity, population health and food supply chain). Therefore, we use an exploratory map to build roadmap to a successful integration of these three attributes. Purpose: social determinants of health are considered as a precondition for population health. Food security forms basis for catalyst in population health. Food security touches human dignity. Many people face starvation while tons of foods are wasted globally. There is a mismatch between supply and demand for food production and consumption. Distributions of foods from producers to consumers become a focal point in managing starvation and waste/glut of foods. The purpose of this paper is to investigate how food supply chain mitigates food insecurity and provides sustainable food supply. Findings: this paper reveals mismatch between supply and consumption of food at a global scale. Inadequate supply chain assets -technologies, storages, distribution networks, etc. - at the producer’s ends causes lower return on investments for producers. Unique characteristics of food supply chain compared with commercial supply chain raises challenges to the imbalance between supply and demand. Oligopolistic market structure may solve the chronic mismatch. Originality/value: literature addresses these three constructs – food security, population health and food supply chain – separately and independently from each other. This paper argues these three constructs should be addressed together in order to solve global food insecurity and waste. As far as we know, this is the first attempt to unify these three constructs.

Child malnutrition in Afghanistan amid a deepening humanitarian crisis.

Decades of political turmoil and stifling war, among other issues, has turned Afghanistan into the world's largest humanitarian crisis. Just 4months after the Taliban seized control, the majority of the Afghan population face starvation, with >3.3 million children unable to afford basic food resources, leading to dozens of deaths every week. Restrictions on humanitarian assistance, withholding of vital food supplies and inadequate medical care play a major role in exacerbating the rates of malnutrition in the vulnerable paediatric population. Global interference is warranted to avoid unfathomable consequences in mitigating this public health catastrophe.

“What Does that Flag Mean to Them?” Rural Relief, Children’s Suffering, and American Philanthropy in Cuba

Abstract This article explores the transnational politics of hunger, philanthropy, and rural reconstruction during the U.S. occupation of Cuba (1899–1902). In the wake of Cuba’s final War of Independence (1895–1898), tens of thousands of reconcentrados—rural civilians forcibly removed from their lands by Spanish forces during the war—continued to face starvation, disease, and homelessness in the island’s western towns and cities. The Cuban Industrial Relief Fund, a U.S.-based philanthropy, hoped to return the reconcentrados to their now-overgrown lands and help them rebuild their homes and farms. The organization connected rural Cubans and ordinary Americans through the complex bonds of transnational philanthropy just as Americans were working out the meanings of American power and responsibility in the new post-1898 world. Early during the U.S. occupation of Cuba, debates over rural reconstruction and relief became a central locus for Americans to articulate the meanings of U.S. power in Cuba. These meanings, however, were refracted through American understandings of childhood, race, and poverty, as paternalist understandings of poverty as cultural failure and colonial depictions of Latin Americans as childlike and untrustworthy shaped debates over the future of rural Cuba. Based on newly available organizational records as well as Cuban and U.S. archival and popular press sources, this article argues that while the goals of the CIRF were to return the Cuban peasantry to a state of self-sufficient independence, entrenched racialized U.S. perceptions of the Cuban poor as lazy, irresponsible, and essentially dependent doomed the prospects of any large-scale industrial relief for Cuban reconcentrados.

The Autophagy Genes ChATG4 and ChATG8 Are Required for Reproductive Development, Virulence, and Septin Assembly in Cochliobolus heterostrophus

Autophagy is a highly conserved degrading process that is crucial for cell growth and development in eukaryotes, especially when they face starvation and stressful conditions. To evaluate the functions of Atg4 and Atg8 in mycelial growth, asexual and sexual development, and virulence in Cochliobolus heterostrophus, ΔChatg4 and ΔChatg8 mutants were generated by gene replacement. Strains deleted for ChATG4 and ChATG8 genes showed significant changes in vegetative growth and development of conidia and ascospores compared with the wild-type strain. The autophagy process was blocked and virulence was reduced dramatically in ΔChatg4 and ΔChatg8 mutants. In addition, deletion of ChATG4 and ChATG8 disordered Cdc10 subcellular localization and formation of septin rings. The direct physical interaction between ChAtg4 and ChAtg8 was detected by yeast two-hybrid assay, and ChAtg4-GFP was dispersed throughout the cytoplasm, although GFP-ChAtg8 appeared as punctate structures. All phenotypes were restored in complemented strains. Taken together, these findings indicate that ChATG4 and ChATG8 are crucial for autophagy to regulate fungal growth, development, virulence, and localization of septin in C. heterostrophus.

Metabolic depression in sea urchin barrens associated with food deprivation.

The proliferation of sea urchins can raze macroalgal forests in coastal ecosystems. Such phenomena can reduce some of the most productive ecosystems on the planet (Schiel and Foster 2015) to low productivity "urchin barrens" (Filbee-Dexter and Scheibling 2014). Although urchins inhabiting these food-depauperate barrens face starvation, many survive in these barrens for years or decades by eating food subsidies from drift algae (Rodríguez 2003, Vanderklift and Wernberg 2008, Britton-Simmons et al. 2009, Renaud et al. 2015, Quintanilla-Ahumada et al. 2018), pelagic salps (Duggins 1981), tubeworms (Spindel and Okamoto personal observation), as well as encrusting and filamentous algae, microbial mats, and slow-growing species resistant to herbivory (Ling and Johnson 2009, Filbee-Dexter and Scheibling 2014, Rasher et al. 2020).

Sufferings and Starvation in Kamala Markandaya’s Nectar in a Sieve

Kamala Markandaya is one of the best known contemporary Indian novelists. Her novels are remarkable for their range of experience. Her first novel Nectar in a Sieve is set in a village and it examines the hard agricultural life of the south Indian village where industry and modern technology played havoc. Kamala Markandaya occupies a very important position among the women novelist who have made substantial contribution to Indian fiction after the Second World War. Markandaya had not always lived abroad. She was born as Kamala Purnaiya in 1924 in Mysore and she was also a journalist. At some point, she decided to spend 18 months in a village “out of curiosity”. This inspired the setting of her first novel, centred on Rukmani and her husband Nathan. Nectar in a Sieve is remarkable for its portrayal of rustics who live in fear, hunger and despair. It is of the dark future; fear of the sharpness of hunger; fear of blackness of death. Almost all the characters in this novel lead miserable life and most of them fail to survive. There are at least a couple of them who were not successfully struggle and have the concept of survival. This novel tells the story of landless peasants of India who face starvation, oppression, breakup of family, home and death. Yet they retain their compassion, love, the strength to face their life and take delight in the little pleasures of the daily existence.

POME Treatment Technology Using Biological and Physical Methods: A Review

Palm oil mills have been identified as one of the main sources of environmental pollution as they generate both solid (decanter cake) and liquid [palm oil mill effluent (pome)] wastes. It is vital for the palm oil industry to implement effective measures in order to mitigate its environmental impacts. The chemical oxygen demand (COD) and the biological oxygen demand (BOD), of the effluent daily analysed by the mill laboratory are important parameters related to the intensity of the environmental impacts on the wastewater. The organic content in the effluent contributes towards the BOD and its relevance lies in the oxygen content of the water courses (usually rivers) into which the effluent is discharged. At values in excess of 100 ppm in the effluent stream, the water source will face starvation of oxygen resulting in the destruction of their marine life. POME can be treated with algae or specific aquatic plants. Past researches were carried out on the potential of Chlamydomonas incerta, Pistia stratiotes, Ipomoea aquatica, Chrysopogon zizanioides and Eichhornia crassipes in combating environmental concerns. The result shows that Eichhornia crassipes is able to reduce COD, BOD, N and P by up to 50, 90, 88 and 64 per cent respectively. Meanwhile, palm oil mill effluent (POME) can be treated by composting, a physical method using the plant E. crassipes, which was found to be the most effective biological method for POME treatment because its effectiveness in reducing contaminants was higher than other aquatic plants and microalgae. This review discusses several potential methods that are accepted and observed in other related researches and how biological methods compare with physical method for POME treatment. Keywords: Palm oil mill effluent, aquatic plants, phytoremediation, biological method, physical method.

Is This Just Fantasy?

Is This Just Fantasy? Stacey Alex (bio) Woven in Moonlight Isabel Ibañez Page Street Kids www.pagestreetpublishing.com 400 Pages; Print, $10.99 For its engagement with cultural identity, the history of Latin American colonization, and contemporary Bolivian politics, Isabel Ibañez’s debut novel, Woven in Moonlight, is an exciting addition to the realm of YA fantasy. From page one, Ibañez creates a sense of urgency in the fictional land of Inkasisa with strong, capable women at the wheel. Having been overthrown by the indigenous Llacsans, the formerly elite Illustrians are forced to retreat to a magically protected keep and face starvation. Tension builds between the royal Condesa Catelina and her decoy, Ximena, as Ximena holds the authority to make decisions for which the the Condesa is held responsible and she feels the Condesa is too eager to please the public. Word arrives that their general, Ana, has been taken captive by the Llacsans and can only be saved if the Condesa marries the Llacsan King Atoc. Ximena has just weeks of wedding preparations to impersonate the Condesa in the Llacsan-controlled castle and plan a revolution. What ensues is a masterfully crafted story of a young woman determined to restore power to her people but challenged to reexamine her prejudices and worldview. Ibañez exquisitely incorporates Andean culture, Quechua, and Spanish to build a binary between Illustrians and Llacsans that the protagonist learns to question. The Illustrians pray to the moon goddess, Mama Killa, while the Llacsans worship the earth goddess Pachamama and the sun god Inti. The olive-skinned Illustrians wear white while the bronze skinned Llacsans wear bright colors and repaint the city surfaces with lush greens and murals. Ximena’s potential for bridging this cultural binary grows from affectionate memories [End Page 10] of her Llacsan nanny who taught her the Llacsan art of weaving. The loom, at first used to relay secret messages back to her Condesa, provides her first taste of culture shock with Llacsan norms, and eventually empowers Ximena to fully realize her magical abilities to create animated woolen animals that become her protectors. At a time when young readers are learning to flex and stretch their cognitive muscles, young adult literature often invites them to reshape the categories for understanding the realities that they have inherited. Readers may grapple along with Ximena’s internal struggle as the Llacsan people she meets challenge what she believes about the Llacsan people. Their kindness creates a cognitive dissonance that permits Ximena to recognize multiple cultural histories and the dehumanization caused by colonization. Her Llacsan maid’s Quechua name, Suyana, means “hope” and points to the transformative power of their human connection. Ximena learns that her guard, Juan Carlos, has a Castilian name because he is a mestizo, of both Castilian and indigenous heritage. This discovery works to further disrupt her binary understanding. When confronted by Rumi, a healer, about the mistreatment of Llacsans under Illustrian rule, Ximena clings to her own preconceptions: The Llacsans were never mistreated. It was their choice to stay up by the mountain, their choice to hold on to their old ways and not embrace the future. The Illustrian queen wanted them to assimilate. She wanted a unified country, and they ungratefully protested her rule. While Ibañez expressly draws on the marginalization of indigenous groups in Bolivia, readers in the United States from a wide variety of minoritized groups may hear their histories described in this racist mythology. Ximena steels herself to not care “un pepino” about the Llacsans and focuses instead on finding a magical relic capable of destroying them. Yet, as she is expected to take part in daily life in the castle, she is afforded unique position of an outsider experiencing an insider’s life and point of view. For example, she is asked to imagine what it must have been like for Llacsans to be prohibited from attending school. The elite Illustrians also continue to control the water supply and withhold it from Llacsans, perhaps alluding to the long struggle over natural gas in Bolivia and public rejection of its privatization. Slowly, Ximena begins to realize the role her own people...

Biodegradation of Cellulose in Laboratory-Scale Bioreactors: Experimental and Numerical Studies

Standard tests such as ISO 17556 (Plastics - determination of the ultimate aerobic biodegradability in soil by measuring the oxygen demand in a respirometer or the amount of carbon dioxide evolved. International Organization for Standardization, Geneva, Switzerland, 2019) or ASTM D5988 (Standard test method for determining aerobic biodegradation of plastic materials in soil. ASTM International, West Conshohocken, 2018) have been developed for measuring the biodegradation of polymers and assessing their biodegradability in soil. In several experiments performed according to these standard tests, the measured biodegradation of cellulose was reported unexpectedly between 80 and 85%. These results are difficult to justify since cellulose is a well-known biodegradable material. In the present study, this phenomenon is explained as the consequence of starvation occurring in a confined bioreactor. It is proposed that the favourable conditions applied to the small-size bioreactors accelerate the proliferation of the microorganisms which are responsible for the biodegradation. Such a dense microbial population may face starvation when cellulose is consumed. It is assumed that starvation causes the secretion of an inhibitory chemical signal, which can diffuse to neighbouring sites still containing food, and suppresses biodegradation. This hypothesis was supported by two experiments. First, it was shown that the final measured biodegradation increased when the microbial growth rate decreased by reducing temperature. In the second experiment, it was shown that the biodegradation proceeded slower when a new cellulose quantity was inserted into a previously used soil substrate. To confirm the hypothesis regarding the presence of an inhibitory starvation factor, which can suppress biodegradation, a Kinetic Monte Carlo (KMC) model was also developed. The KMC simulations reproduced qualitatively the experimental findings.

Introduction Des Organismes Génétiquement Modifiés(OGM) Dans L’agriculture En Côte d’Ivoire: Etat De Connaissance Et Souhaits Des Populations De Six (6) Localités Du Sud Du Pays

Transgenic plants with their huge potential as the high yields, resistance to diseases, insects and water stress seem to be a solution for Africa and could contribute to poverty reduction and the increase of agricultural production in this area of the world often face starvation. However GMOs dragging a trail of controversy and risk maligned with a series of impacts that concern the human health, environmental, social and economic. Is the dangerousness of transgenic plants a concern people of Ivory Coast? Investigations were carried out on 400 farmers and 1000 educated people in through a series of questions.

Plant defences wear vole teeth

In the fields of Northern Europe, a tundra vole (Microtus oeconomus) population explosion could be going on right now. As they hit the reproductive jackpot, their numbers rocket. But with most booms there comes a bust, and the same is true for vole populations, which can collapse suddenly and unexpectedly. Ivan Calandra, from the University of Reims Champagne-Ardenne, France, explains that the cause of these dramatic population crashes was not clear, although there was one candidate that could account for the dramatic fall from grace: the vegetation upon which the voles feast. Plants are not as vulnerable as they may at first appear. ‘It has been known for at least 30 years that plants build up silica bodies (phytoliths) in response to intense grazing,’ says Calandra. But it was not clear whether these plant defences were directly responsible for the vole's demise, and if they were, how? Were the abrasive silica structures that accumulate in plant cells wrecking the rodents' teeth or damaging their intestines, leading to starvation and population collapse?Karol Zub, Andrzej Zalewski and Paulina Szafrańska, from the Polish Academy of Sciences, decided to feed voles on two diets – one composed of pellets containing high levels of sedge, which is reinforced with silica, and another in which the sedge was replace with lower-silica grasses – to find out how different levels of silica affected the rodents’ teeth. Then Zub and Szafrańska shipped the voles’ teeth to Gildas Merceron, a CNRS Researcher at the University of Poitiers, France, where he and Calandra could look for any damage using one of only four profilometers – confocal microscopes that scan surfaces to produce 3D representations of structures – that can analyse tooth wear.However, when the duo compared the damage on the surface of teeth that the voles had used to grind their food, they were surprised to see little difference between the patterns of wear in animals on the different diets, possibly because the lab diets were not optimal. However, Calandra's Polish colleagues also knew that voles switch diet from season to season, dining on high-silica sedges in the winter and spring before supplementing the diet with softer, low-silica leafy vegetation in the summer and autumn. In addition, Calandra explains that sedges retaliate as the vole population expands by arming themselves with increased silica levels. Could the team find differences in tooth wear if they investigated the wear patterns in different populations of voles across the years and seasons as the silica levels increased in response to the expanding populations?This time the team investigated vole teeth from animals that had been trapped in the wild from the late 1970s to 2001, including a period when the population crashed in 2000 after peaking the previous year. And this time, having scanned the surface of 47 teeth, they found evidence of changes in wear pattern as the voles shifted their diet through the seasons and as the sedges became more impregnated with silica.However, the team warns that this evidence of changes in tooth wear may not account for vole population crashes, saying, ‘Tooth wear rates might seem unimportant in voles since their molars are ever-growing’. They also add that there is no clear mechanism linking the effects of tooth wear to dramatic reductions in vole population, although they suspect that if the teeth are worn unevenly, the animals may have difficulties feeding and face starvation.

Selection bias in the link between child wantedness and child survival: theory and data from Matlab, Bangladesh.

We examine the potential effects of selection bias on the association between unwanted births and child mortality from 7,942 women from Matlab, Bangladesh who declared birth intentions in 1990 prior to conceiving pregnancies. We explore and test two opposing reasons for bias in the distribution of observed births. First, some women who report not wanting more children could face starvation or frailty; and if these women are infecund, the remaining unwanted births would appear more healthy. Second, some women who report not wanting more children could have social privileges in acquiring medical services, abortion, and contraceptives; and if these women avoid births, the remaining unwanted births would appear less healthy. We find (1) no overall effect of unwantedness on child survival in rural Bangladesh in the 1990s, (2) no evidence that biological processes are spuriously making the birth cohort look more healthy, and (3) some evidence that higher schooling for women who avoid unwanted births is biasing the observed sample to make unwanted births look less healthy. Efforts to understand the effect of unwantedness in data sets that do not control for complex patterns of selective birth may be misleading and require more cautious interpretation.

Projected polar bear sea ice habitat in the Canadian Arctic Archipelago.

BackgroundSea ice across the Arctic is declining and altering physical characteristics of marine ecosystems. Polar bears (Ursus maritimus) have been identified as vulnerable to changes in sea ice conditions. We use sea ice projections for the Canadian Arctic Archipelago from 2006 – 2100 to gain insight into the conservation challenges for polar bears with respect to habitat loss using metrics developed from polar bear energetics modeling.Principal FindingsShifts away from multiyear ice to annual ice cover throughout the region, as well as lengthening ice-free periods, may become critical for polar bears before the end of the 21st century with projected warming. Each polar bear population in the Archipelago may undergo 2–5 months of ice-free conditions, where no such conditions exist presently. We identify spatially and temporally explicit ice-free periods that extend beyond what polar bears require for nutritional and reproductive demands.Conclusions/SignificanceUnder business-as-usual climate projections, polar bears may face starvation and reproductive failure across the entire Archipelago by the year 2100.

A Packet Priority Approach to Mitigate Starvation in Wireless Mesh Network with Multimedia Traffic

Mesh Networks (WMN) faces the inherent problem of increased end to end delay over a multiple hop wireless link. The delay becomes more obvious as the number of hops count between the source and destination increases. Experimental results have shown two hop neighbours face starvation when there are one hop nodes within the same gateway. In this paper, it is proposed to study the effect of starvation in WMN for multimedia traffic which are governed by the end to end delay and jitter for QOS. A novel packet priority technique, Dynamic Weighted Round Robin (DWRR) is proposed to reduce the effect of starvation for multi hop nodes. The proposed technique is implemented and compared with network without packet priority techniques. Results show that the proposed technique can be used to reduce starvation in WMN.

Effect of starvation and refeeding on amino acid metabolism in muscle of crab Neohelice granulata previously fed protein- or carbohydrate-rich diets

The present study assesses the effects of starvation and refeeding on 1-[14C]-methyl aminoisobutyric acid (14C-MeAIB) uptake, 14C-total lipids, 14CO2 production from 14C-glycine, 14C-protein synthesis from 14C-leucine and Na+–K+-ATPase activity in jaw muscle of Neohelice granulata previously maintained on a carbohydrate-rich (HC) or high-protein (HP) diet. In N. granulata the metabolic adjustments during starvation and refeeding use different pathways according to the composition of the diet previously offered to the crabs. During starvation, 14CO2 production from 14C-glycine, and 14C-protein synthesis from 14C-leucine were reduced in HC-fed crabs. In crabs maintained on the HP or HC diet, 14C-total lipid synthesis increased after 15days of starvation. In crabs fed HP diet, 14C-MeAIB uptake and Na+–K+-ATPase activity decreased in refeeding state. In crabs refeeding HC diet, 14C-MeAIB uptake and 14CO2 production decreased during the refeeding. In contrast, the 14C-protein synthesis increased after 120h of refeeding. In both dietary groups, 14C-total lipid synthesis increased during refeeding. Changes in the carbon amino acid flux between different metabolic pathways in muscle are among the strategies used by this crab to face starvation and refeeding. Protein or carbohydrate levels in the diet administered to this crab modulate the carbon flux between the different metabolic pathways.

Yemen: Descending into Despair

Yemen: Descending into Despair

Dietary patterns of children aged 0‐59 months in Ukambani region of Kenya

ObjectiveSevere drought struck Northern and Eastern Kenya in 2006 that forced ~10% of Kenyan population to face starvation, and subsequent malnutrition in children. We assessed the dietary patterns of children aged 0‐59 months in Mwingi (MW) and Makueni (MA), two drought‐stricken districts in Eastern Kenya. Mwingi district uses pearl millet as the main staple cereal while Makueni uses maize (corn).MethodsWe interviewed 403 mothers to collect dietary information about their children from 4 randomly selected locations in MW and MA. Surrogate 24‐hr recalls from 614 children (300 boys and 314 girls) were obtained, and subsequently entered using NDSR 2008. Nutrients were transformed to achieve normality. Intake of selected nutrients and food groups were compared between the two districts using t‐test.ResultsAverage (mean ± SD) energy intake (1064+499 kcal) in MW was significantly higher compared to MA (966 + 470 kcal) (p<0.05). Intake of carbohydrate, protein, iron and most B vitamins were significantly higher in MW compared to MA; fat, animal protein and vitamin A were significantly higher in MA. On average, grains contribute 55‐60% of total energy intake in both districts. The contribution to total energy from grains, vegetables and milk were significantly higher in MW compared to MA.ConclusionOverall, children in Mwingi have higher nutritional intake compared to Makueni.

Energy reserves during food deprivation and compensatory growth in juvenile roach: the importance of season and temperature

The effect of 21 days of starvation, followed by a period of compensatory growth during refeeding, was studied in juvenile roach Rutilus rutilus during winter and summer, at 4, 20 and 27° C acclimation temperature and at a constant photoperiod (12L : 12D). Although light conditions were the same during summer and winter experiments and fish were acclimated to the same temperatures, there were significant differences in a range of variables between summer and winter. Generally winter fish were better prepared to face starvation than summer fish, especially when acclimated at a realistic cold season water temperature of 4° C. In winter, the cold acclimated fish had a two to three‐fold larger relative liver size with an approximately double fractional lipid content, in comparison to summer animals at the same temperature. Their white muscle protein and glycogen concentration, but not their lipid content, were significantly higher. Season, independent of photoperiod or reproductive cycle, was therefore an important factor that determined the physiological status of the animal, and should generally be taken into account when fish are acclimated to different temperature regimes. There were no significant differences between seasons with respect to growth. Juvenile roach showed compensatory growth at all three acclimation temperatures with maximal rates of compensatory growth at 27° C. The replenishment of body energy stores, which were utilized during the starvation period, was responsible for the observed mass gain at 4° C. The contribution of the different energy resources (protein, glycogen and lipid) was dependent on acclimation temperature. In 20 and 27° C acclimated roach, the energetic needs during food deprivation were met by metabolizing white muscle energy stores. While the concentration of white muscle glycogen had decreased after the fasting period, the concentrations of white muscle lipid and protein remained more or less constant. The mobilization of protein and fat was revealed by the reduced size of the muscle after fasting, which was reflected in a decrease in condition factor. At 20° C, liver lipids and glycogen were mobilized, which caused a decrease both in the relative liver size and in the concentration of these substrates. Liver size was also decreased after fasting in the 4° C acclimated fish, but the substrate concentrations remained stable. This experimental group additionally utilized white muscle glycogen during food deprivation. Almost all measured variables were back at the control level within 7 days of refeeding.

Sigma 54 levels and physiological control of the Pseudomonas putida Pu promoter.

The cellular levels of the alternative sigma factor sigma(54) of Pseudomonas putida have been examined in a variety of growth stages and culture conditions with a single-chain Fv antibody tailored for detection of scarce proteins. The levels of sigma(54) were also monitored in P. putida strains with knockout mutations in ptsO or ptsN, known to be required for the C-source control of the sigma(54)-dependent Pu promoter of the TOL plasmid. Our results show that approximately 80 +/- 26 molecules of sigma(54) exist per cell. Unlike that in relatives of Pseudomonas (e.g., Caulobacter), where fluctuations of sigma(54) determine adaptation and differentiation when cells face starvation, sigma(54) in P. putida remains unexpectedly constant at different growth stages, in nitrogen starvation and C-source repression conditions, and in the ptsO and ptsN mutant strains analyzed. The number of sigma(54) molecules per cell in P. putida is barely above the predicted number of sigma(54)-dependent promoters. These figures impose a framework on the mechanism by which Pu (and other sigma(54)-dependent systems) may become amenable to physiological control.