Genotyping of pantophysin I (Pan I) of Atlantic cod (Gadus morhua L.) by allele‐specific PCR

The two main allelic variants of the Atlantic cod (Gadus morhua L.) pantophysin I (Pan I) locus have different frequencies within different cod stocks. The Dra I polymorphism which distinguishes the two alleles can thus be used for discrimination of coastal and offshore cod populations. We present a new method for Pan I genotyping using fluorescent allele‐specific duplex polymerase chain reaction (PCR). This method is more rapid, reliable and cost‐effective than the previously published method and it is not affected by DNA source and quality. This improvement is important for studies demanding high throughput and accuracy of Pan I genotyping     

The synthesis of short- and medium-chain-length poly(hydroxyalkanoate) mixtures from glucose- or alkanoic acid-grown <Emphasis Type="Italic">Pseudomonas oleovorans</Emphasis>

Pseudomonas oleovorans NRRL B-778 accumulated mixtures of poly-3-hydroxybutyrate (PHB) and medium-chain-length poly(hydroxyalkanoates) (mcl-PHAs) when grown on glucose, octanoic acid or oleic acid, whereas growth on nonanoic acid or undecanoic acid resulted in copolymers of poly-3-hydroxybutyrate-co-3-hydroxyvalerate (PHB-co-HV). Acetone fractionation verified the presence of PHB/mcl-PHA mixtures. The acetone-insoluble (AIS) fractions of the polymers derived from glucose (PHA-glucose), octanoic acid (PHA-octanoic) and oleic acid (PHA-oleic) were exclusively PHB while the acetone-soluble (AS) fractions contained mcl-PHA composed of differing ratios of 3-hydroxy-acid monomer units, which ranged in chain length from 6 to 14 carbon atoms. In contrast, both the AIS and AS fractions from the polymers derived from nonanoic acid (PHA-nonanoic) and undecanoic acid (PHA-undecanoic) were composed of comparable ratios of 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV). The unfractionated PHA-glucose, PHA-octanoic and PHA-oleic polymers had melting temperatures (T _m) between 177 and 179°C, enthalpies of fusion (ΔH _f) of 20 cal/g and glass transition temperatures (T _g) of 3–4°C. This was due to the large PHB content in the polymer mixtures. On the other hand, the PHA-nonanoic and PHA-undecanoic polymers had thermal properties that supported their copolymer nature. In both cases, the T _m values were 161°C, ΔH _f values were 7cal/g and T _g values were −3°C. Journal of Industrial Microbiology & Biotechnology (2002) 28, 147–153 DOI: 10.1038/sj/jim/7000231 Received 30 July 2001/ Accepted in revised form 04 November 2001     

Efficient use of reactive nitrogen for cultivation of bioenergy: less is more

A further increase in nitrogen (N) intensive biomass supplies to substitute fossil carbon sources implies inclusion of additional reactive nitrogen (Nr) into the biosphere. A Danish model study compared low‐intensity managed seminatural beech forest and a winter wheat system with respect to N losses and greenhouse gas (GHG) emissions. Losses of reactive N to air and groundwater per unit of energy produced were four to six times higher for the winter wheat system. The energy efficiency was an order of magnitude higher in the forest system, whereas the related GHG emission reduction by fossil coal substitution differed by <25%. The question is whether a low or a high intensity of cultivation yields the best overall ecosystem service performance? Given the detrimental effect of excess reactive N on natural ecosystems, we suggest that bioenergy production from unfertilized forest with seminatural structure and function should be preferred over N‐intensive crop production.     

Symbiosome-like intracellular colonization of cereals and other crop plants by nitrogen-fixing bacteria for reduced inputs of synthetic nitrogen fertilizers

It has been forecast that the challenge of meeting increased food demand and protecting environmental quality will be won or lost in maize, rice and wheat cropping systems, and that the problem of environmental nitrogen enrichment is most likely to be solved by substituting synthetic nitrogen fertilizers by the creation of cereal crops that are able to fix nitrogen symbiotically as legumes do. In legumes, rhizobia present intracellularly in membrane-bound vesicular compartments in the cytoplasm of nodule cells fix nitrogen endosymbiotically. Within these symbiosomes, membrane-bound vesicular compartments, rhizobia are supplied with energy derived from plant photosynthates and in return supply the plant with biologically fixed nitrogen, usually as ammonia. This minimizes or eliminates the need for inputs of synthetic nitrogen fertilizers. Recently we have demonstrated, using novel inoculation conditions with very low numbers of bacteria, that cells of root meristems of maize, rice, wheat and other major non-legume crops, such as oilseed rape and tomato, can be intracellularly colonized by the non-rhizobial, non-nodulating, nitrogen fixing bacterium, Gluconacetobacter diazotrophicus that naturally occurs in sugarcane. G. diazotrophicus expressing nitrogen fixing (nifH) genes is present in symbiosome-like compartments in the cytoplasm of cells of the root meristems of the target cereals and non-legume crop species, somewhat similar to the intracellular symbiosome colonization of legume nodule cells by rhizobia. To obtain an indication of the likelihood of adequate growth and yield, of maize for example, with reduced inputs of synthetic nitrogen fertilizers, we are currently determining the extent to which nitrogen fixation, as assessed using various methods, is correlated with the extent of systemic intracellular colonization by G. diazotrophicus, with minimal or zero inputs.     

Physiological Studies in Plant Nutrition: XVII. A General Survey of the Free Amino-acids of Barley Leaves as affected by Mineral Nutrition, with Special Reference to Potassium Supply

A survey by means of paper chromatography of the free amino-acidsin barley leaves at different stages of development is described.The plants were grown in sand culture, using a variety of nutrientsolutions, the most important variable being potassium supply.In general, the amino-acid distribution is not greatly affectedby nutritional differences. Potassium deficiency results in much increased contents of theamides, especially asparagine, and reduced amounts of the correspondingacids. Other acids increased under these conditions are serine,leucine, tyrosine, and phenylalanine, but the most characteristicchanges occur in -the basic constituents; lysine and arginineare increased, and an unknown basic substance accumulates verycharacteristically. Accumulation of this substance (probablyan amine) is checked by the presence of either sodium or rubidiumin the culture solution, almost as effectively as by increasedpotassium supply. Extreme potassium deficiency yields chromatogramsclosely resembling those from more moderately deficient plants. When a low rubidium supply accompanies potassium shortage thedisturbances occasioned by potassium deficiency, both in growthand in amino-acid distribution, are diminished, but a higherrubidium supply leads to toxic symptoms in the plant; largeincreases in the contents of the two amides and of their parentacids are then found, this being the only condition encounteredthat leads to simultaneous accumulation of both these typesof substances.     

Balance between Potassium and Phosphorus in the Nutrition of Barley: I. The Influence on Amine Content

Potassium-deficient barley accumulates the amines agmatine andputrescine, the latter of which is known to produce necroticspots on the leaves in some seasons. The severity of potassiumdeficiency symptoms is strongly influenced by the external levelof phosphorus. An experiment was conducted in water culture,using two-week-old barley to discover whether amine accumulationwas similarly affected. Four levels of potassium —1/64,1/6, 1/4, and 1/1 of full supply—were combined factoriallywith the same levels of phosphorus, the diagonal in this designbeing a series of ‘balanced’ solutions in whichpotassium and phosphorus were present in the same ratio as inthe full nutrient. The plants were sampled three times duringthe ten-week period of growth, and the form of the results wassimilar each time. Whenever potassium was reduced, putrescinecontent rose above normal, but for large amounts of putrescineto be accumulated, phosphorus supply had to be in excess ofpotassium. The highest levels of agmatine were also found wherepotassium was low and phosphorus in excess, but significantaccumulations also developed whenever phosphorus was low relativeto potassium, that is, where high levels of potassium were observedin the plants. Since agmatine and putrescine are very closely related biochemicallyand together make up 90 per cent of the amine content of barley,the influence of potassium and phosphorus on their summed contentwas considered. Potassium was found to have the dominant effect:at any one level of phosphorus supply, the summed content wasminimal at the highest level of potassium, and reduction inpotassium always increased it. The effect of phosphorus dependedon the degree of imbalance between potassium and phosphorusin the nutrient. High summed contents were found where eitherpotassium or phosphorus was present in excess, and minimum contentwas found where the levels were balanced. There were significantpartial correlations between summed amine content and the potassiumand phosphorus contents of the plants. The high significanceof correlations between amine content and the proportion ofdead and moribund shoot material suggested that amine accumulationmight be partly responsible for the rapid death of the leavesof the deficient plants as well as for the production of necroses,which are only limited in area.     

Two New Species of Hartmannella Amebae Infecting Freshwater Mollusks

SYNOPSIS. Two new species of small amebae, Hartmannella biparia n. sp. and Hartmannella quadriparia n. sp., were 1st observed in the freshwater mollusks Bulinus globosus and Biomphalaria pallida, respectively. The amebae multiplied in cytoplasmic vacuoles in host cells, particularly in foci in the mantle collar, foot, and intestinal wall. Both amebae had functional contractile vacuoles while within host cells. H. biparia emerged from intracytoplasmic vacuoles in pairs, H. quadriparia in fours, suggesting characteristic reproductive stages.
H. biparia had limax-type motility by smooth lobopodia, was 22 μ long; with vesicular nucleus 3 μ and central endosome 1.5 μ, multiplied by binary fission and formed spherical, smooth-walled cysts 11 μ in diameter. H. quadriparia had limax-type motility by lobopodia with fine, acute projections; was 10 μ long, with vesicular nucleus 2 μ and central endosome 0.75 μ, multiplied and formed spherical, smooth-walled cysts 5 μ in diameter. Neither species multiplied in cysts outside the host.
H. biparia was found infecting 12 species and experimentally transferred to 4 more species of freshwater snails; H. quadriparia was found in one species and experimentally transferred to 6 other species.