Aquatic Primary Production

The ecosystem concept has been particularly useful and extensivelyemployed in the study of aquatic primary productivity. The flowof energy through the system is an attractive area of investigationwhen it involves some process, but has a more restricted valuewhen units of biomass are simply converted to calories. Althoughwe are able to measure primary productivity in terms of thecarbon fixed, we are not yet able to measure the actual changein the oxidative state of the newly fixed carbon. The fate ofphotosynthate as food for higher trophic levels is thereforedependent upon a considerable array of biological and environmentalvariables. Primary productivity is considered in terms of itsevolution from measures of standing crop and yield, which havebeen gradually replaced by measures of rate of carbon uptakeor oxygen production, or by measure of nutrient loss, or bychange of CO₂ in the environment. Data from five lakes are usedto illustrate the evolutionary thread of eutrophication andthe great range in primary productivity to be expected on thebasis of either unit volume or unit surface area at differenttrophic states. Light and nutrients are important in limitingprimary productivity, and are contributing factors to the greatvariability which one may encounter within a given lake. Onlywith a sounder understanding of productivity at the base ofthe food-chain can we have any real hope of controlling theproductivity of aquatic environments for the benefit of man.     

Relative Importance of H2 and H2S as Energy Sources for Primary Production in Geothermal Springs

Geothermal waters contain numerous potential electron donors capable of supporting chemolithotrophy-based primary production. Thermodynamic predictions of energy yields for specific electron donor and acceptor pairs in such systems are available, although direct assessments of these predictions are rare. This study assessed the relative importance of dissolved H₂ and H₂S as energy sources for the support of chemolithotrophic metabolism in an acidic geothermal spring in Yellowstone National Park. H₂S and H₂ concentration gradients were observed in the outflow channel, and vertical H₂S and O₂ gradients were evident within the microbial mat. H₂S levels and microbial consumption rates were approximately three orders of magnitude greater than those of H₂. Hydrogenobaculum-like organisms dominated the bacterial component of the microbial community, and isolates representing three distinct 16S rRNA gene phylotypes (phylotype = 100% identity) were isolated and characterized. Within a phylotype, O₂ requirements varied, as did energy source utilization: some isolates could grow only with H₂S, some only with H₂, while others could utilize either as an energy source. These metabolic phenotypes were consistent with in situ geochemical conditions measured using aqueous chemical analysis and in-field measurements made by using gas chromatography and microelectrodes. Pure-culture experiments with an isolate that could utilize H₂S and H₂ and that represented the dominant phylotype (70% of the PCR clones) showed that H₂S and H₂ were used simultaneously, without evidence of induction or catabolite repression, and at relative rate differences comparable to those measured in ex situ field assays. Under in situ-relevant concentrations, growth of this isolate with H₂S was better than that with H₂. The major conclusions drawn from this study are that phylogeny may not necessarily be reliable for predicting physiology and that H₂S can dominate over H₂ as an energy source in terms of availability, apparent in situ consumption rates, and growth-supporting energy.     

A Center of Primary Sources for Plains Indian History

Abstract

Preservation of the nation’s Indian records is recogni: zed as a task of national importance. Public access to government documents and data is now possible at ten regional records centers across the country. The material stored provides detailed and analytic accounts of daily activity and business at Indian agencies. The nature and content of the data relevant to Plains Indian agencies is described in this paper.     

Primary Sources of Phosphorus and Phosphates in Chemical Evolution

In this work we consider the role of phosphorus in chemical evolution from an interdisciplinary approach. First we briefly review the presence of this element in different cosmic sites, such as massive stellar cores, circumstellar and interstellar clouds, meteorites, lunar and Martian samples, interplanetary dust particles, cometary dust and planetary atmospheres. Thus we illustrate the fact that phosphorus seems to be, at the same time, scarce and ubiquitous in the solar system. Afterwards, by comparing the phosphorus content of our planet's main reservoirs with the amount of cometary and meteoritic matter captured by the primitive Earth, we conclude that comets may have provided a primary source for phosphorus compounds of prebiotic interest. Finally, we make a number of proposals aimed to gain observational supporting evidence to the above conclusion and other suggestions made in the article.     

Primary Production in Terrestrial Ecosystems

"Primary production" refers to energy fixed by plants. The totalamount of energy fixed is usually called "gross production."A certain fraction of gross production is used in respirationby the plants; the remainder appears as new biomass or "netprimary production." Thus for a single plant or a communityof green plants: Net Primary Production = Gross Production – Respiration(of Autotrophs) Similar relationships occur in ecosystems except that the organicmatter and respiration of heterotrophs must be included. Theincrease in total organic matter is "net ecosystem production";respiration is the total respiration of the green plants (autotrophs)and the animal community and decay organisms (heterotrophs).Gross production is of course identical to that of the plantcommunity. Thus for an ecosystem: Net Ecosystem Production = Gross Production – Respiration(of Autotrophs and Heterotrophs) Study of these attributes of terrestrial ecosystems is difficult,both because of the complex interrelations of the processesinvolved, and because of the problems of working with systemsas large as whole forests. Three approaches are in use: (1)Harvest techniques measure weight increase (and caloric equivalentand chemical composition) of net production. A refinement otthis approach based on "dimension analysis" has made possibleimportant recent advances in the study of forests. Other techniquesapproach gross production and respiration through measurementof exchange of gases, especially CO₂. These include: (2) Enclosurestudies, involving measurements of CO₂ exchange in plastic enclosuresof parts of ecosystems and (3) Flux techniques based on measurementof CO₂ levels in the environment. All three approaches are beingapplied to a forest at Brookhaven National Laboratory to determinethe production equation of this ecosystem. Results to date have established general ranges of such parametersof ecosystems as total biomass, total surface area of leavesand of stems and branches, rates of decay of organic matterin soils, rates of production of roots, and rates of photosynthesisand respiration under different environmental conditions. Inthe Brookhaven forest net primary production is 1124 dry g/m²/yr(with an energy equivalent of 492 cal/cm²/yr), and gross productionis about 2550 dry g/m²/yr; the producers or green plants thusrespire 56% of their gross production. Net ecosystem productionis 422 dry g/m²/yr in this young forest. The ratio of totalrespiration to gross production is a convenient expression ofsuccessional status; a value of 0.82 for the Brookhaven forestindicates that this is a late successional community, but notin steady-state or climax condition (1.0). A leaf surface areaof 3.8 m² per m² of ground surface intercepts sunlight energy,and the ratio of net primary production to incident visiblesunlight energy gives a net efficiency of primary productionof 0.0088. These and other functional characteristics of ecosystems arecurrently important topics of research—involving understandingof communities as biological systems, evaluation of the potentialof environments to support life and man's harvest; and understandingof the fundamental meaning and consequences of man's alteration,exploitation, and pollution of ecosystems.     

Utilization of Non-Sugar Sources for Vitamin B12 Production

Assimilation of non-sugar carbon sources for vitamin B₁₂ production was studied.     

Ceramic Production in the American Southwest

Ceramic Production in the American Southwest, Barbara J. Mills and Patricia L. Crown. eds. Tucson: University of Arizona Press, 1995. 310 pp.     

Herbivory and Stoichiometric Feedbacks to Primary Production

Established theory addresses the idea that herbivory can have positive feedbacks on nutrient flow to plants. Positive feedbacks likely emerge from a greater availability of organic carbon that primes the soil by supporting nutrient turnover through consumer and especially microbially-mediated metabolism in the detrital pool. We developed an entirely novel stoichiometric model that demonstrates the mechanism of a positive feedback. In particular, we show that sloppy or partial feeding by herbivores increases detrital carbon and nitrogen allowing for greater nitrogen mineralization and nutritive feedback to plants. The model consists of differential equations coupling flows among pools of: plants, herbivores, detrital carbon and nitrogen, and inorganic nitrogen. We test the effects of different levels of herbivore grazing completion and of the stoichiometric quality (carbon to nitrogen ratio, C:N) of the host plant. Our model analyses show that partial feeding and plant C:N interact because when herbivores are sloppy and plant biomass is diverted to the detrital pool, more mineral nitrogen is available to plants because of the stoichiometric difference between the organisms in the detrital pool and the herbivore. This model helps to identify how herbivory may feedback positively on primary production, and it mechanistically connects direct and indirect feedbacks from soil to plant production.     

Effect of Different Carbon Sources on Endochitinase Production by Colletotrichum gloeosporioides

The present work analyzes the production of endochitinase by Colletotrichum gloeosporioides, a phytopathogenic fungus, using six different carbon sources and two pH values. For quantitative assay of endochitinase activity in solution, the synthetic substrate 4-methylumbelliferyl-β-D-N,N’,N”-triacetylchitotrioside was used. The major productions were obtained at pH 7.0 and 9.0, when colloidal chitin and glucose were used, whereas xylose and lactose were not good carbon sources. When testing different concentrations of colloidal chitin, glucose and glucosamine, colloidal chitin 0.5% was the best substrate, giving values of 2.4 U at the fifth day. When using glucose, best production occurred at 0.3% concentration, after 5 days growth, with values of 1.31 U. Endochitinase production was markedly decreased in high levels of glucose and in all glucosamine concentrations tested. SDS-PAGE co-polymerized with glycol-chitin analysis showed three major activity bands of 200, 100, and 95 kDa, when incubated at 50°C.     

Sources of Variability in Net Primary Production Predictions at a Regional Scale: A Comparison Using PnET-II and TEM 4.0 in Northeastern US Forests

Because model predictions at continental and global scales are necessarily based on broad characterizations of vegetation, soils, and climate, estimates of carbon stocks and fluxes made by global terrestrial biosphere models may not be accurate for every region. At the regional scale, we suggest that attention can be focused more clearly on understanding the relative strengths of predicted net primary productivity (NPP) limitation by energy, water, and nutrients. We evaluate the sources of variability among model predictions of NPP with a regional-scale comparison between estimates made by PnET-II (a forest ecosystem process model previously applied to the northeastern region) and TEM 4.0 (a terrestrial biosphere model typically applied to the globe) for the northeastern US. When the same climate, vegetation, and soil data sets were used to drive both models, regional average NPP predictions made by PnET-II and TEM were remarkably similar, and at the biome level, model predictions agreed fairly well with NPP estimates developed from field measurements. However, TEM 4.0 predictions were more sensitive to regional variations in temperature as a result of feedbacks between temperature and belowground N availability. In PnET-II, the direct link between transpiration and photosynthesis caused substantial water stress in hardwood and pine forest types with increases in solar radiation; predicted water stress was relieved substantially when soil water holding capacity (WHC) was increased. Increasing soil WHC had little effect on TEM 4.0 predictions because soil water storage was already sufficient to meet plant demand with baseline WHC values, and because predicted N availability under baseline conditions in this region was not limited by water. Because NPP predictions were closely keyed to forest cover type, the relative coverage of low- versus high-productivity forests at both fine and coarse resolutions was an important determinant of regional NPP predictions. Therefore, changes in grid cell size and differences in the methods used to aggregate from fine to coarse resolution were important to NPP predictions insofar as they changed the relative proportions of forest cover. We suggest that because the small patches of high-elevation spruce-fir forest in this region are substantially less productive than forests in the remainder of the region, more accurate NPP predictions will result if models applied to this region use land cover input data sets that retain as much fine-resolution forest type variability as possible. The differences among model responses to variations in climate and soil WHC data sets suggest that the models will respond quite differently to scenarios of future climate. A better understanding of the dynamic interactions between water stress, N availability, and forest productivity in this region will enable models to make more accurate predictions of future carbon stocks and fluxes. Received 19 June 1998; accepted 25 June 1999.     

Mutations in DHDPSL Are Responsible For Primary Hyperoxaluria Type III

Primary hyperoxaluria (PH) is an autosomal-recessive disorder of endogenous oxalate synthesis characterized by accumulation of calcium oxalate primarily in the kidney. Deficiencies of alanine-glyoxylate aminotransferase (AGT) or glyoxylate reductase (GRHPR) are the two known causes of the disease (PH I and II, respectively). To determine the etiology of an as yet uncharacterized type of PH, we selected a cohort of 15 non-PH I/PH II patients from eight unrelated families with calcium oxalate nephrolithiasis for high-density SNP microarray analysis. We determined that mutations in an uncharacterized gene, DHDPSL, on chromosome 10 cause a third type of PH (PH III). To overcome the difficulties in data analysis attributed to a state of compound heterozygosity, we developed a strategy of “heterozygosity mapping”—a search for long heterozygous patterns unique to all patients in a given family and overlapping between families, followed by reconstruction of haplotypes. This approach enabled us to determine an allelic fragment shared by all patients of Ashkenazi Jewish descent and bearing a 3 bp deletion in DHDPSL. Overall, six mutations were detected: four missense mutations, one in-frame deletion, and one splice-site mutation. Our assumption is that DHDPSL is the gene encoding 4-hydroxy-2-oxoglutarate aldolase, catalyzing the final step in the metabolic pathway of hydroxyproline.     

Sources of Biomass Feedstock Variability and the Potential Impact on Biofuels Production

Terrestrial lignocellulosic biomass has the potential to be a carbon neutral and domestic source of fuels and chemicals. However, the innate variability of biomass resources, such as herbaceous and woody materials, and the inconsistency within a single resource due to disparate growth and harvesting conditions, presents challenges for downstream processes which often require materials that are physically and chemically consistent. Intrinsic biomass characteristics, including moisture content, carbohydrate and ash compositions, bulk density, and particle size/shape distributions are highly variable and can impact the economics of transforming biomass into value-added products. For instance, ash content increases by an order of magnitude between woody and herbaceous feedstocks (from ～0.5 to 5 %, respectively) while lignin content drops by a factor of two (from ～30 to 15 %, respectively). This increase in ash and reduction in lignin leads to biofuel conversion consequences, such as reduced pyrolysis oil yields for herbaceous products as compared to woody material. In this review, the sources of variability for key biomass characteristics are presented for multiple types of biomass. Additionally, this review investigates the major impacts of the variability in biomass composition on four conversion processes: fermentation, hydrothermal liquefaction, pyrolysis, and direct combustion. Finally, future research processes aimed at reducing the detrimental impacts of biomass variability on conversion to fuels and chemicals are proposed.© 2015 Battelle Energy Alliance, LLC, contract manager for Idaho National Laboratory.     

Taxonomic Significance of Phenethyl Alcohol Production by Achromobacter Isolates from Fishery Sources

The formation of phenethyl alcohol from L-phenylalanine and ethanol by achromobacter isolates of fishery origin was found to be taxonomically significant for such organisms. Phenylpyruvate, the direct oxidative deamination product of L-phenylalanine, was found to serve as an intermediate precursor to phenethyl alcohol formation. Among ten Acinetobacter isolates examined, none produced phenethyl alcohol. Among nine Moraxella isolates examined, one produced phenethyl alcohol.     

华南南亚热带植被第一性生产量的影响因素及预测模型

讨论植被类型、降雨、湿度、土壤条件对华南南亚热带植被第一性生产量的影响。比较各种预测第一性生产量的气候模型,为更好地预测和提高华南南亚热带植被第一性生产量提供依据。     

Iron Constraints on Planktonic Primary Production in Oligotrophic Lakes

Phototrophic primary production is a fundamental ecosystem process, and it is ultimately constrained by access to limiting nutrients. Whereas most research on nutrient limitation of lacustrine phytoplankton has focused on phosphorus (P) and nitrogen (N) limitation, there is growing evidence that iron (Fe) limitation may be more common than previously acknowledged. Here we show that P was the nutrient that stimulated phytoplankton primary production most strongly in seven out of nine bioassay experiments with natural lake water from oligotrophic clearwater lakes. However, Fe put constraints on phytoplankton production in eight lakes. In one of these lakes, Fe was the nutrient that stimulated primary production most, and concurrent P and Fe limitation was observed in seven lakes. The effect of Fe addition increased with decreasing lake water concentrations of total phosphorus and dissolved organic matter. Possible mechanisms are low import rates and low bioavailability of Fe in the absence of organic chelators. The experimental results were used to predict the relative strength of Fe, N, and P limitation in 659 oligotrophic clearwater lakes (with total phosphorus ≤ 0.2 μM P and total organic carbon < 6 mg C l⁻¹) from a national lake survey. Fe was predicted to have a positive effect in 88% of these lakes, and to be the nutrient with the strongest effect in 30% of the lakes. In conclusion, Fe, along with P and N, is an important factor constraining primary production in oligotrophic clearwater lakes, which is a common lake-type throughout the northern biomes. This paper is dedicated to the memory of Prof. Peter Blomqvist (deceased 2004).     

Primary and Bacterial Secondary Production in a Southwestern Reservoir

Rates of primary and bacterial secondary production in Lake Arlington, Texas, were determined. The lake is a warm (annual temperature range, 7 to 32°C), shallow, monomictic reservoir with limited macrophyte development in the littoral zone. Samples were collected from six depths within the photic zone from a site located over the deepest portion of the lake. Primary production and bacterial production were calculated from NaH¹⁴CO₃ and [methyl-³H]thymidine incorporation, respectively. Peak instantaneous production ranged between 14.8 and 220.5 μg of C liter⁻¹ h⁻¹. There were two distinct periods of high rates of production. From May through July, production near the metalimnion exceeded 100 μg of C liter⁻¹ h⁻¹. During holomixis, production throughout the water column was in excess of 100 μg of C liter⁻¹ h⁻¹ and above 150 μg of C liter⁻¹ h⁻¹ near the surface. Annual areal primary production was 588 g of C m⁻². Bacterial production was markedly seasonal. Growth rates during late fall through spring were typically around 0.002 h⁻¹, and production rates were typically 5 μg of C liter⁻¹ h⁻¹. Growth rates were higher during warmer parts of the year and reached 0.03 h⁻¹ by August. The maximum instantaneous rate of bacterial production was approximately 45 μg of C liter⁻¹ h⁻¹. Annual areal bacterial production was 125 g of C m⁻². Temporal and spatial distributions of bacterial numbers and activities coincided with temporal and spatial distributions of primary production. Areal primary and bacterial secondary production were highly correlated (r = 0.77, n = 15, P < 0.002).     

The Production of Antifungal Metabolites by Pseudomonas chlororaphis Grown on Different Nutrient Sources

It was found that the antifungal activity of Pseudomonas chlororaphis SPB1217 is due to phenazine-1-carboxylic acid, phenazine-1-carboxamide, and two unidentified exometabolites. The carbon source used for the growth of this bacterial strain and iron ions present in the medium considerably influenced the proportion between the antifungal metabolites. The maximum production of phenazines was observed in the media enriched in amino acids and iron ions. The absence of correlation between the production of phenazines and antifungal activity indicates that phenazines are not the only antifungal metabolites of the strain. Organic acids as nutrient sources provide for more intense production of exometabolites and for a higher level of antifungal activity than sugars.     

Distinguishing between Nitrification and Denitrification as Sources of Gaseous Nitrogen Production in Soil

The source of N₂O produced in soil is often uncertain because denitrification and nitrification can occur simultaneously in the same soil aggregate. A technique which exploits the differential sensitivity of these processes to C₂H₂ inhibition is proposed for distinguishing among gaseous N losses from soils. Denitrification N₂O was estimated from 24-h laboratory incubations in which nitrification was inhibited by 10-Pa C₂H₂. Nitrification N₂O was estimated from the difference between N₂O production under no C₂H₂ and that determined for denitrification. Denitrification N₂ was estimated from the difference between N₂O production under 10-kPa C₂H₂ and that under 10 Pa. Laboratory estimates of N₂O production were significantly correlated with in situ N₂O diffusion measurements made during a 10-month period in two forested watersheds. Nitrous oxide production from nitrification was most important on well-drained sites of a disturbed watershed where ambient NO₃⁻ was high. In contrast, denitrification N₂O was most important on poorly drained sites near the stream of the same watershed. Distinction between N₂O production from nitrification and denitrification was corroborated by correlations between denitrification N₂O and water-filled pore space and between nitrification N₂O and ambient NO₃⁻. This technique permits qualitative study of environmental parameters that regulate gaseous N losses via denitrification and nitrification.