Different zooplankton structures in the German Bight

In August 1982, a net of 48 stations with altogether 208 samples was investigated in the eastern German Bight with respect to temperature, salinity, as well as the amount and species composition of the mesozooplankton (>80 μm). The data were arranged into different structures by means of a cluster analysis. Four different clusters were found: (a) a “Wadden sea water” with few holoplankton organisms but a higher amount of spionid larvae; (b) a “German Bight water” with a maximum occurrence of turbellaria (Alaurina composita) and medium concentrations of copepods; (c) a mixing area between these two water masses with highest amounts ofOikopleura dioica, Temora longicornis, Acartia sp., mussel larvae and larvae of the spionid worms; (d) a “North Sea water” mass with highest concentrations ofPseudocalanus elongatus, Paracalanus parvus undOithona similis. The differences in the concentrations of the species mentioned between the four clusters were significant on the 0.1%-level.     

Seismic Stress Responses of Soybean to Different Photosynthetic Photon Flux

Physical agitation applied as periodic seismic stress (shaking)reduced stem clongation, leaf expansion, and biomass accumulationby vegetative soybeans. Level of photon flux (PPF) influencedthe type and extent of plant response to mechanical stress.Plant parts responded differently as PPF varied between 135and 592 µmol m^–2 S^–1. Stem length was significantlyreduced by seismic stress at 135 µmol m^–2 s^–1but this effect was insignificant at higher PPFs. Reduced stemlength resulted from an inhibition of internode elongation.Stem diameter was unaffected by stress at the PPFs tested. Incontrast to effects on stem elongation, leaf area was insensitiveto stress treatments at 135 µmol m^–2 S^–1 butwas progressively inhibited by stress as PPF increased. Statisticallysignificant reductions in shoot f. wt and d. wt by seismic stressoccurred only at 295 µmol m^–2 S^–1. Root biomassaccumulation was not affected by seismic stress at any PPF usedin this study. Glycine max (L.) Merr. cv. Century 84, mechanical stress, photosynthetic photon flux, seismic stress, soybean     

Analysis of Odor Discrimination by Multidimensional Scaling at Different Temperatures

Discrimination of odorants by the turtle olfactory bulb at 25°and 37°C was examined by the cross-adaptation techniqueand analysed by multidimensional scaling. Analysis by multidimensionalscaling suggests that at 25°C odorants are grouped accordingto their odor qualities in the turtle olfactory system. At 37°C,the cluster formation of odorants, which have a similar odorquality, such as minty and floral alcohol odorants and molecularstructure, in the plot of multidimensional scaling was poor,indicating that the ability of odor grouping according to theirodor qualities was low at 37°C. Chem. Senses 20: 565–571,1995.     

Different behaviour of crop species in phosphate absorption

Summary Isotopic-dilution technique was used to study the differential phosphate absorption abilities of several field crops. The response of crops was found to be inversely related to the ratio of phosphorus absorbed from the soil to that absorbed from the fertilizer. The ‘A’ values ranged from 2.03 ppm for mustard to 21.77 ppm for soybeans. A highly significant correlation (r=0.77**) was found between per cent yields and the ‘A’ values.     

Grain Size and Seedling Growth of Wheat at Different Ploidy Levels

A study was made of the influence of grain size variation withinand between diploid, tetraploid and hexaploid wheat, on a numberof seedling growth characters. Differences in grain size within the three ploidy levels appearedto be related to total photosynthetic area and dry weight accretionin the seedling. In the diploids there was a positive correlationbetween seed size and total photosynthetic area (r = +0·99,P < 0·01) and total dry weight (r = +0·84,P < 0·05) of the seedling at 10 weeks after emergence.In the tetraploid and hexaploids, seed size was negatively correlatedwith both total photosynthetic area (r = –0·69,P < 0·05 and r = –0·33, P < 0·05for the tetraploids and hexaploids respectively) and total dryweight (r = –0·69, P < 0·05 and r = –0·59,P < 0·05 for the tetraploids and hexaploids respectively),of the seedlings 10 weeks after emergence. The main physiological distinction between the tetraploids andhexaploids appeared to be the superiority of the hexaploidsin rate of leaf appearance and the lower ratio of expanded tounexpanded leaves in the seedling 10 weeks after emergence.The tetraploids, in turn, appeared to be superior to the diploidsin these two characters. Triticum spp., wheat, polyploidy, grain size, photosynthetic area, net assimilation rate, tiller number     

Serum and Testicular Trace Element Concentration in Rabbits at Different Ages

Trace elements such as Zinc (Zn), copper (Cu), iron (Fe), and selenium (Se) are essential for male fertility. The fertilizing capacity of most animals reduced with advancing age. The objective of the present work was to determine the serum and testicular levels of Zn, Cu, and Se in young (10 months old) and old (30 months old) rabbits. Blood and testicular samples were obtained from rabbits after their slaughter. All samples were digested by concentrated acids and analyzed for trace elements by flame emission atomic absorption spectrophotometer. The results showed that serum Zn and Cu were lower in old rabbits than young (P < 0.01). Serum Se was higher in old than young rabbits (P < 0.05). Testicular Cu and Se were significantly lower in old than young rabbits (P < 0.01). However, Zn level was higher in old compared to young rabbits (P < 0.01). The serum Zn and Se were higher than the testicular levels (P < 0.01). The testicular Cu in both ages was higher than the serum level (P < 0.01), which suggest a very important role for Cu in the process of spermatogenesis in rabbits.     

Effect of Different Iodine Nutrition on Cerebellum Pcp-2 in Rat Offspring During Lactation

The thyroid functions of breastfed infants, as well as (indirectly) the development of their central nervous system, are dependent on the iodine status of the lactating mother. Purkinje cell protein-2 is a cell-specific marker of the cerebellum Purkinje cell and is a suitable indicator for observing the postnatal development of the cerebellum after birth. We measured the Purkinje cell protein-2 mRNA and protein levels in the rat cerebellum in the critical postnatal (14 days after birth) and maturation periods (28 days after birth) to determine the effect of different nutritional iodine levels on cerebellum growth in the offspring during lactation. We found that severe iodine deficiency resulted in thyroid dysfunction in lactating rats and their offspring on both 14 and 28 days, showing maternal total T₄ 16.7 ± 12.0 vs 36.4 ± 15.0, P < 0.05 (14 days) and 22.6 ± 18.7 vs 53.4 ± 9.4, P < 0.01 (28 days), and neonatal total T₄ 10.6 ± 2.3 vs 16.4 ± 4.7, P < 0.01(14 days) and 12.8 ± 2.9 vs 16.7 ± 3.4, P < 0.05 (28 days), respectively. The Purkinje cell protein-2 mRNA and its protein levels in offspring rats were significantly reduced that showed Purkinje cell protein-2 mRNA 1.12 ± 0.04 vs 2.25 ± 0.53, P < 0.05 (14 days) and 1.74 ± 0.94 vs 8.69 ± 2.71, P < 0.01 (28 days). However, mild iodine deficiency and excessive iodine maintained almost normal thyroid function in maternal and neonatal rats and normal Purkinje cell protein-2 mRNA and protein levels in offspring’s cerebellum. We conclude that severe iodine deficiency could significantly reduce Purkinje cell protein-2 mRNA and its protein levels, indicating that the cerebellum development was retarded, but mild iodine deficiency and excessive iodine could maintain them at an approximately normal level by the mother’s and offspring’s compensations, especially by the mother’s mammary glands.     

The In Vitro Culture of Immature Barley Embryos on Different Culture Media

Immature barley embryos (Hordeum distichum var. Julia) of between0•20 and 0•80 mm in length, were isolated from thedeveloping grain and cultured in vitro on various culture media.The subsequent development of the embryos was followed overa period of weeks, and where germination ensued the growth rateof shoot and root meristems was compared with in vivo germinationrates. Various growth media were assessed for their abilityto support normal development of immature embryos. A numberof published media failed to support satisfactory developmentof young embryos. The addition of 1–15 per cent coconutmilk to Norstog's Medium I (mineral + vitamin solns) enhancedembryo development and lowered the threshold of viability fromembryos of 0•50 mm in length to 0•35 mm. Althoughin many cases germination ensued, embryo development was largelyabnormal. A slightly greater enhancement of growth was achievedwith 0•05–0•30 per cent casein hydrolysate asthe growth medium supplement, although abnormal developmentwas not eliminated. A further lowering of the viability thresholdto include embryos of 0•25 mm in length was obtained bycombining 2•7 mM glutamine with the casein hydrolysatesupplement. Normal development and germination of embryos assmall as O25 mm was however obtained on Norstog's Medium JJand the results were reproduced in four additional if . distichumvarieties. In each case the critical threshold of viabilitywas found to lie in embryos of 0•20–0•30 mmin length.     

Mitochondrial Permeability Transition Induced by Different Concentrations of Zinc

Zinc is one of the required trace elements in animals, and it serves an important role in biological systems. However, high levels of zinc are poisonous to organisms. So far, there exist conflicting reports about zinc ions-induced mitochondrial permeability transition (MPT). We analyzed the effects of Zn²⁺ on MPT by monitoring mitochondrial swelling with the ultraviolet–visible light absorption spectrum, characterizing the fluidity of the membrane with fluorescence anisotropy, detecting the transmembrane potential (Δψ) with fluorescence intensity, and observing mitochondrial ultrastructure with transmission electron microscopy. Data reveal that low concentrations of zinc ions can trigger MPT while high levels of zinc ions cannot, which implies that zinc ions’ toxicity cannot be the result of a single simple mechanism.     

Responses of Quercus ilex from Different Provenances to Experimentally Imposed Water Stress

Responses of Quercus ilex L. seedlings from three different localities in Italy to experimentally imposed drought stress were analysed. Predawn (Ψ_pd) and midday (Ψ_m) leaf water potential of stressed seedlings decreased on an average until −4.0 and −4.2 MPa, respectively, in the severe water stress. At the end of the severe water stress the relative water content (RWC) was 72.5 – 83.6 % and the photosynthetic rates (P_N) near zero. The critical threshold value of Ψ_pd for complete stomatal closure was from −4.0 to −4.5 MPa. The leaf damage after the severe water stress was significantly greater in seedlings originated from the acorns of climax area (45 % total leaf injured area and 40 % fallen leaves) than in the other seedlings (on an average 20.5 % total leaf injured area and 21 % fallen leaves). This revised version was published online in July 2006 with corrections to the Cover Date.     

A Kinetic Examination of Penicillin Acylase Stability in Water-organic Solvent Systems at Different Temperatures

We have studied the thermal stability of penicillin acylase from Streptomyces lavendulae in water-organic solvent monophasic systems at the range of temperatures between 40 and 60°C. We found a linear correlation between the log &#117 P value of the solvent and the activation free energy for denaturation ( &#106 G d ) at all temperatures tested. Thermodynamic analysis of the results indicates that solvents with log &#117 P &#104 &#109 2.3 have protective effects, whereas solvents with log &#117 P &#83 &#109 1.8 are deleterious for penicillin acylase.     

Nitrous Oxide Emission from Grazed Grassland Under Different Management Systems

Nitrous oxide (N₂O) emissions from grazed grasslands are estimated to be approximately 28% of global anthropogenic N₂O emissions. Estimating the N₂O flux from grassland soils is difficult because of its episodic nature. This study aimed to quantify the N₂O emissions, the annual N₂O flux and the emission factor (EF), and also to investigate the influence of environmental and soil variables controlling N₂O emissions from grazed grassland. Nitrous oxide emissions were measured using static chambers at eight different grasslands in the South of Ireland from September 2007 to August 2009. The instantaneous N₂O flux values ranged from -186 to 885.6 μg N₂O-N m⁻² h⁻¹ and the annual sum ranged from 2 ± 3.51 to 12.55 ± 2.83 kg N₂O-N ha⁻¹ y⁻¹ for managed sites. The emission factor ranged from 1.3 to 3.4%. The overall EF of 1.81% is about 69% higher than the Intergovernmental Panel on Climate Change (IPCC) default EF value of 1.25% which is currently used by the Irish Environmental Protection Agency (EPA) to estimate N₂O emission in Ireland. At an N applied of approximately 300 kg ha⁻¹ y⁻¹, the N₂O emissions are approximately 5.0 kg N₂O-N ha⁻¹ y⁻¹, whereas the N₂O emissions double to approximately 10 kg N ha⁻¹ for an N applied of 400 kg N ha⁻¹ y⁻¹. The sites with higher fluxes were associated with intensive N-input and frequent cattle grazing. The N₂O flux at 17°C was five times greater than that at 5°C. Similarly, the N₂O emissions increased with increasing water filled pore space (WFPS) with maximum N₂O emissions occurring at 60–80% WFPS. We conclude that N application below 300 kg ha⁻¹ y⁻¹ and restricted grazing on seasonally wet soils will reduce N₂O emissions.     

Inter-population Variations of Kochia indica During Germination Under Different Stresses

Germination of three populations of Kochia indica Wight fromcontrasting soil types were studied under various levels ofsalinity, alkalinity and osmotic stress with a view to evaluatetheir potential to establish through seeds in saline and alkalineenvironments of various magnitudes. The seeds were germinatedunder controlled conditions in Petri dishes using salinizedsolutions of NaCl, Na₂SO₄, MgCI₂ and CaSO₄ (electrical conductivity,EC, 4–16 ds m^–), sodium carbonate solutions (pH8.5–100), mannitol solutions ( – 2.5 to –100 bar) and de-ionised distilled water (control). Inter-populationdifferences were very marked, showing selective adaptation ofthe populations to a particular stress type. In general, allpopulations exhibited salt tolerance but were rather sensitiveto high osmotic stress. Kochia indica Wight (bui), germination, population, salinity, alkalinity, osmotic stress     

Different forms of nitrogen in particle size fractions separated from two soils

Summary The possible use of particle size separation of soils in water was tested for preparing fractions rich in ‘unknown’-N, which constitutes between 41 and 46% of the total N. Ten particle size fractions ranging from <0.2 to>1,000.0 μm were separated from the A horizon of the Bainsville soil, an Orthic Humic Gleysol, and from the Bh horizon of the Armadale soil, a poorly drained Podzol. The distribution of N (hydrolyzable-, amino acid-, protein-, amino sugar-, ammonia-, ‘unknown’-and unidentified-N) in the initial soils and in each size fraction was determined. While particle size separation did not yield fractions which contained essentially only ‘unknown’-N and few known N-components, it was possible to isolate fractions which were either rich in amino acid-or protein-N or in NH₃-N. In general, the finer size fractions tended to be enriched in amino acid-N while NH₃-N was more prominent in the coarser fractions. The amino sugar-N content of all size fractions was low.     

Properties of Mitochondria Prepared by Two Different Isolation Procedures From the Cotyledons of Germinating Bean Seedlings

Mitochondria from 1-day-old bean cotyledons were isolated bya ‘slow’ isolation procedure involving a wash andby a ‘rapid’ procedure. The mitochondria isolatedby the ‘rapid’ procedure were more tightly coupledthan those isolated by the ‘slow’ procedure. Anexogenous supply of cytochrome c or NAD was shown to improvethe activity of mitochondria isolated by the ‘slow’procedure, but not those isolated by the ‘rapid’procedure. The phosphorylative abilities of the latter weremuch greater than the former and were retained for longer periods.It was found that there was a leakage of NAD out of the mitochondria.     

Photosynthetic Electron Transport under Phosphorylating Conditions as Influenced by Different Concentrations of Various Salts

Osman, M. E-A. H. and El-Shentenawy, F. 1988. Photosyntheticelectron transport under phosphorylating conditions as influencedby different concentrations of various salts.—J. exp.Bot. 39: 859–863. The rate of light-induced electron transport by isolated spinachthylakoids under phosphorylating conditions, as affected bydifferent concentrations of Br^–, Cl^–, NO₃^–,HCO₃^–, SO₄^2– and CO₃^2– has been investigated.The results show that both low and high concentrations of HCO₃^2–stimulated the oxygen evolution capacity under phosphorylatingconditions, whereas only low concentrations of CO₃^2–,SO₄^2– and Cl^– stimulated the oxygen evolution capacity.However, irrespective of concentration, both Br^– and NO₃^–reduced this capacity. The rate of photosynthetic electron transportwas generally stimulated by addition of ADP, even in cases whereelectron transport was inhibited by addition of bromide andnitrate. The different concentrations of these anions also causedreduction of the power generated by proton pumping and usedfor phosphorylation. The greatest level of reduction was observedin the presence of high concentrations of Cl^– and HCO₃^–. Key words: Spinach thylakoids, photosynthetic electron transport, phosphorylation     

Bacterial Diversity in Three Different Antarctic Cold Desert Mineral Soils

A bacterial phylogenetic survey of three environmentally distinct Antarctic Dry Valley soil biotopes showed a high proportion of so-called “uncultured” phylotypes, with a relatively low diversity of identifiable phylotypes. Cyanobacterial phylotypic signals were restricted to the high-altitude sample, whereas many of the identifiable phylotypes, such as the members of the Actinobacteria, were found at all sample sites. Although the presence of Cyanobacteria and Actinobacteria is consistent with previous culture-dependent studies of microbial diversity in Antarctic Dry Valley mineral soils, many phylotypes identified by 16S rDNA analysis were of groups that have not hitherto been cultured from Antarctic soils. The general belief that such “extreme” environments harbor a relatively low species diversity was supported by the calculation of diversity indices. The detection of a substantial number of uncultured bacterial phylotypes showing low BLAST identities (<95%) suggests that Antarctic Dry Valley mineral soils harbor a pool of novel psychrotrophic taxa.     

Critical Levels of Selenium in Different Crops Grown in an Alkaline Silty Loam Soil Treated with Selenite-Se

Critical levels of selenium in raya (Brassica juncea Czern L.), maize (Zea mays L.), wheat (Triticum aestivum L.) and rice (Oryza sativa L.) were worked out by growing these crops in an alkaline silty loam soil treated with different levels of selenite-Se ranging from 1 to 25 μg g⁻¹ soil. Significant decrease in dry matter yield was observed above a level of 5 μg Se g⁻¹ soil in raya and maize; 4 μg Se g⁻¹ soil in wheat and 10 μg Se g⁻¹ soil in rice shoots. The critical level of Se in plants above which significant decrease in yield would occur was found to be 104.8 μg g⁻¹ in raya, 76.9 μg g⁻¹ in maize, 41.5 μg g⁻¹ in rice and 18.9 μg g⁻¹ in wheat shoots. Significant coefficients of correlation were observed between Se content above the critical level and dry matter yield of raya as well as rice (r = −0.99, P ≤ 0.01), wheat (r = −0.97, P ≤ 0.01) and maize ((r = −0.96, P ≤ 0.01). A synergistic relationship was observed between S and Se content of raya (r = 0.96, P ≤ 0.01), wheat (r = 0.89, P ≤ 0.01), rice (r = 0.85, P ≤ 0.01) and maize (r = 0.84, P ≤ 0.01). Raya, maize and rice absorbed Se in levels toxic for animal consumption (i.e. > 5 mg Se kg⁻¹) when the soil was treated with more than 1.5 μg Se g⁻¹. In case of wheat, application of Se more than 3 μg g⁻¹ soil resulted in production of toxic plants.     

Selenium Distribution in Camel Blood and Organs After Different Level of Dietary Selenium Supplementation

Eight young female camels shared in four groups of two 2 years received a basal diet enriched respectively with 0, 2, 4, and 8 mg selenium under sodium selenite form for 64 days. Feed intake was assessed daily; blood samples were taken on weekly basis. One camel from each group was killed at the end of the experiment. Se concentration in serum was increased significantly in the supplemented groups with an average of 176.3 ± 18.0 ng/mL in the control group, 382.7 ± 107.6 in the group receiving 2 mg Se, 519.8 ± 168.4 in the group receiving 4 mg Se, and 533.4 ± 158.6 in the group receiving 8 mg Se daily. For glutathione peroxidase (GSH-Px) activity, the control group (51.0 IU/g Hb) and the group receiving 2 mg (50.5 IU/g Hb) were significantly different than groups receiving 4 and 8 mg (respectively, 65.9 and 76.1 IU/g Hb). No significant variation occurred for vitamin E (mean, 0.56 ± 0.23 ng/mL). Significant correlation between serum Se and GSH-Px was reported. Kidney was the richest organ in selenium followed by lung, spleen, and liver, but the increase in supplemented groups was more marked in liver and kidney. The hair seemed to be the best indicator of selenium intake in camel.     

Carbon Dioxide Exchange of Spring-wheat in Relation to Age and Photon-flux Density at Different Growth Temperatures

CO₂-exchange rates (CER) of the sixth and the flag leaves oftwo spring-wheat varieties, Kolibri and Famos, were comparedusing an open-circuit infrared gas analysing system. Measurementswere repeated every two weeks starting when leaf blades werefully expanded. Single plants were grown in a controlled environmenthaving a photopuiod of 15 h and a day/night temperature of 24/19°C(H), 18/13 °C (M), and 12/7 °C (L) respectively untilapprox. 2 weeks after anthesis and at 18/13 °C until maturity.The photosynthetic photon-flux density (PPFD) at the top ofthe plants was 500 µE m^–2 sec^–1. During themeasurements PPFD was gradually reduced from 2000 to 0 µEm^–2 sec^–1 whereas the temperature was maintainedat the respctive growth-temperatures during the light period.The CER of the sixth leaf declined fairly similarly for bothvarieties, except for Kolibri where a faster decline was observedduring the first two weeks after full leaf expansion. The CERof the flag leaf declined more slowly than that of the sixthleaf. With the flag leaf of Famos, the decline was nearly linear,whereas with Kolibri it was very slow during the first few weeksbut rapid as the leaves further senesced. This pattern becamemore pronounced as the growth temperature decreased. The declinein relation to leaf age was much smaller at low PPFD than athigh PPFD during the same period. At full leaf expansion Kolibrireached higher maximum CER than Famos except at H. As the PPFDwas reduced the difference became smaller and at very low PPFDsuch as 50 µE m^–2 sec^–1 was reversed for thesixth leaf. Under optimum growth conditions maximum values ofCER were greater than 50mg CO₂ dm^–2h^–1 and PPFDfor light saturation was close to 2000 µE m^–2 sec^–1.A comparison between the actual CER and a fitted curve widelyused, PN=(a+b/l)^–1–DR, showed that the goodnessof fit strongly depends on cultivar, treatment and leaf ageas well as on the number and the level of PPFD from which datafor calculations are taken. Triticum aestivum, L., wheat, photosynthesis, photon-flux density, light response, carbon, dioxide exchange