The effect of the virus-serum incubation period upon vaccinia virus serum neutralization titers

Rabbit and human vaccinia virus immune sera were titrated by the plaque reduction serum neutralization (SN) method. Titers determined following a 2-h, 37 degree C virus-serum incubation period were not significantly different from those determined following an 18-h incubation period (2-h, 37 degree C incubation followed by a 16-h, 4 degree C period). However, control virus plaque counts decreased significantly after the longer incubation period. Numerous factors affecting SN titer estimation are reviewed. Standardization of SN test conditions may be useful in comparative potency evaluation of vaccinia-vectored recombinant DNA viral vaccines.     

The profile distribution of total and extractable boron in cacao-growing soils in southwestern Nigeria

The profile distribution of total and extractable B was determined in 16 Nigerian cacao-growing soil profiles formed from different parent materials. Total B for all soils ranged from 8 to 54μgg⁻¹ with a mean of 24μgg⁻¹. The soils formed from sandstones in the rainforest zone contained higher amounts of total B than soils derived from basement complex. Boron extractable in hot water, in 0.1% CaCl₂, and in 1N NH₄OAc varied from 0.13 to 1.38, 0.44 to 1.20 0.03 to 0.56μgg⁻¹ respectively. The corresponding means were 0.66, 0.75 and 0.27μgg⁻¹ B. Soils on metamorphic rocks gave the highest values. All extractable B values were related to organic matter while only CaCl₂-extractable B correlated with total B. Generally total and extractable B values were higher in the top soils than in the subsoils.     

Patterns of community change among ammonia oxidizers in meadow soils upon long-term incubation at different temperatures

The effect of temperature on the community structure of ammonia-oxidizing bacteria was investigated in three different meadow soils. Two of the soils (OMS and GMS) were acidic (pH 5.0 to 5.8) and from sites in Germany with low annual mean temperature (about 10 degrees C), while KMS soil was slightly alkaline (pH 7.9) and from a site in Israel with a high annual mean temperature (about 22 degrees C). The soils were fertilized and incubated for up to 20 weeks in a moist state and as a buffered (pH 7) slurry amended with urea at different incubation temperatures (4 to 37 degrees C). OMS soil was also incubated with less fertilizer than the other soils. The community structure of ammonia oxidizers was analyzed before and after incubation by denaturing gradient gel electrophoresis (DGGE) of the amoA gene, which codes for the alpha subunit of ammonia monooxygenase. All amoA gene sequences found belonged to the genus Nitrosospira. The analysis showed community change due to temperature both in moist soil and in the soil slurry. Two patterns of community change were observed. One pattern was a change between the different Nitrosospira clusters, which was observed in moist soil and slurry incubations of GMS and OMS. Nitrosospira AmoA cluster 1 was mainly detected below 30 degrees C, while Nitrosospira cluster 4 was predominant at 25 degrees C. Nitrosospira clusters 3a, 3b, and 9 dominated at 30 degrees C. The second pattern, observed in KMS, showed a community shift predominantly within a single Nitrosospira cluster. The sequences of the individual DGGE bands that exhibited different trends with temperature belonged almost exclusively to Nitrosospira cluster 3a. We conclude that ammonia oxidizer populations are influenced by temperature. In addition, we confirmed previous observations that N fertilizer also influences the community structure of ammonia oxidizers. Thus, Nitrosospira cluster 1 was absent in OMS soil treated with less fertilizer, while Nitrosospira cluster 9 was only found in the sample given less fertilizer.     

The effect of tar contamination on the extractable metal levels in soil

Summary Tar contaminated soil was analysed for extractable trace metal content. All the metals analysed, with the exception of Ni, were present at higher levels than in normal agricultural soil. re]19760531     

The relationship between available molybdenum in soils of volcanic ash origin and the molybdenum content in red clover (Trifolium pratense,L) leaves

Summary The relationship between Mo content in red clover leaves and available Mo in two different soil series of volcanic ash origin (Iwate-san and Hizume soils) was studied.If results were treated separately for each soil series, positive single correlations were obtained between leaf Mo and soil Mo extracted by Grigg's pH 3.3, 0.55N ammonium oxalate method. Correlation between leaf Mo and soil Mo was not significant if data from both soil series were combined. This relationship appeared to be due to several factors. First, the recovery of added Mo was lower in Hizume soils than in Iwate-san soils. This tendency for Mo fixation was confirmed by a pot experiment. Second, the amount of Fe as free hydrous Fe oxides dissolved in the acidic ammonium oxalate extract was higher in Hizume soils than in Iwate-san soils. This was negatively correlated with leaf Mo content. Therefore, the multiple correlation and regression between leaf Mo of red clover and available Mo, free hydrous Fe oxides and Mo recovery of soils gave satisfactory results even if data from both soils were combined.However, in the two soils used in this study, extraction at pH 3.3 failed to give the highest yield of Mo. They were obtained at much lower pH even though the concentration of organic acid remained constant. This was particularly clear in Iwate-san soils. The acidic ammonium oxalate extraction procedure tends to underestimate soil Mo availability in these kinds of soils, especially in extraction of Iwate-san soils.     

The trace fossil Sinusichnus from the Upper Ordovician of Anticosti Island,eastern Canada

Branched, sinusoidal burrows assigned to Sinusichnus cf. seilacheri Knaust et al. 2016; occur in Upper Ordovician (Hirnantian) carbonates on Anticosti Island. These are abundant and monospecific at the base of the Oncolite Bed of the uppermost Ellis Bay Formation, marking a regional discontinuity surface during the multiphase Ordovician mass-extinction event. In contrast to Mesozoic and Cenozoic records of Sinusichnus, commonly attributed to the activity of decapod and isopod crustaceans, the burrow systems from Anticosti Island were probably produced by other arthropods of unknown affinity. A combined dwelling, locomotion and feeding behaviour of their trace maker is assumed. This is the oldest record of the ichnogenus Sinusichnus, previously only known since the Triassic, and its first evidence from North America.     

Changes in water extractable metals,pH and organic carbon concentrations at the soil-root interface of forested soils

Soluble metals are of nutritional and ecotoxicological interest as they are the most readily available form to the biota. Metal solubility in soils is mostly controlled by pH and the organic matter content. The rhizosphere is generally considered as an environment enriched in organic matter and often more acidic (depending on nutritional status of the plant) than the bulk soil. Yet, there is a lack of consensus on the distribution of metals at the soil-root interface. Consequently, the specific objectives of this paper are to compare the chemical properties and the water extractable metal concentrations of the rhizosphere and the bulk soil of forest soil (1) along a gradient in soil contamination and (2) under different tree species. Two study areas were used: (1) Rouyn-Noranda (Canada) where samples were collected along a gradient in metal contamination at a distance of 0.5, 2 and 8 km downwind from a copper smelter; (2) Saint-Hippolyte (Canada) where the effect of three tree species (Abies balsamea, Acer saccharum and Betula papyrifera) was studied. In the field, the rhizosphere was operationally defined as the soil adhering to the roots after agitation, soil falling from the roots and the rest of the soil composing the bulk soil. Once in laboratory, a second agitation was performed to separate the rhizosphere into an inner and an outer component. Water extractable metal concentrations (Al, Ca, Cd, Co, Cr, Cu, Fe, Li, Mg, Mn, Ni, Pb and Zn) were quantified either with an ICP-AES or a GFAAS. Measurements of pH, electrical conductivity (EC), water-extractable organic carbon (WEOC) and solid phase organic carbon (SPOC) were performed. Results systematically indicate that EC, WEOC and SPOC follow the sequence inner rhizosphere > outer rhizosphere > bulk soil. The pH is always lower in the inner rhizosphere than in the bulk soil, while the outer rhizosphere frequently shows an inconstant behaviour. The results also show a clear gradient following inner rhizosphere > outer rhizosphere > bulk soil for water extractable Al, Ca, Cd, Cu, Fe, Mg, Mn, Ni, Pb and Zn. Li, Co and Cr levels were below method detection limit in all cases. WEOC seems to be the main variable related to the water-extractable metals concentrations. The gradient in metal contamination at Rouyn-Noranda was not as expected in the water extracts with the site at 2 km frequently presenting higher metal concentrations than the sites at 0.5 and 8 km. Moreover, a tree species effect did not clearly immerge for any of the chemical properties studied. However, the water extractable Ca concentrations were higher in the soil under Acer saccharum. The effects of the metal gradient and of the tree species may be more pronounced if stronger extractants are used. The addition of an outer rhizosphere component is useful as its behaviour is not consistently intermediate between the inner rhizosphere and bulk soil.     

The effect of storage of soils under water-logged conditions upon subsequent mineralization of nitrogen,nitrification and fixation of ammonia

Summary Four soils were incubated for 10 weeks at 29°C, without added nitrogen and with 100 ppm N as (NH₄)₂SO₄ at 65% waterholding capacities, either fresh or after water-logged storage for 1 to 4 months. The amounts of ammonium-N in the soils increased with length of storage period. During subsequent incubation the ammonium-N was nitrified in all soils. Nitrification, however, was delayed for one or more weeks in some of these soils, and was further retarded by adding (NH₄)₂SO₄.Water-logging increased the amounts of nitrogen mineralized on subsequent incubation and decreased the amounts of ammonia fixed after adding (NH₄)₂SO₄. Oxidation of nitrite to nitrate was delayed for the first week following water-logging in a humic clay and the numbers of bacteria decreased as the period of water-logging increased. In the soils water-logged for 3 and 4 months the microbiological balance was not completely restored even after 10 weeks incubation.The numbers of nitrifying organisms were markedly decreased by waterlogging for 2, 3, and 4 months and remained fewer during the incubation period compared with untreated soil. Adding (NH₄)₂SO₄ did not increase numbers of nitrifiers.     

The mechanism of action of molybdenum and tungsten upon collagen structures in vivo

The effect of in vivo administration of molybdenum (as sodium molybdate) and tungsten (as sodium tungstate) was investigated in the skin of laboratory rats. It was proved that the amount of both bound molybdenum and tungsten in collagen is relatively small being 0.05 and 0.06 moles per mole respectively. Besides the fraction of firmly bound molybdenum and tungsten a much higher extractable pool of both these metals was found. It was also demonstrated that in vivo shadowing of collagen is caused by the fraction of loosely bound metals. On the other hand pronounced changes were shown in the mechanical properties of connective tissue after molybdate and tungstate administration. Surprisingly, the change in mechanical properties indicated a lower level of cross-linking after the administration of the investigated metals. It is therefore concluded that bitopical binding of molybdenum and tungsten in the collagen structure is unlikely. It also appears that the biological effect of these metals is due to the competition with copper and the interference with the physiological cross-linking reactions based on the partial blockade of lysyloxidase.     

Aluminium,boron and molybdenum availability and uptake by rice in acid sulfate soils

Although Al toxicity is believed to be a problem in acid sulfate soils cropped to rice (Oryza, sativa L.), little is known about the behavior of other trace metals such as B and Mo in these soils. The objectives of this study were to measure the availability of Al, B, and Mo in these soils, to determine what governs the availability of these metals and to investigate the relationships between metal availability and uptake by rice. Metal availability and uptake by rice were evaluated in 134 flooded acid sulfate soils in the Central Plains region of Thailand and in a growth chamber study using 50 of the same soils. Soil and plant metal analyses were conducted at the panicle differentiation stage of growth in both studies and in the soil prior to transplanting in the growth chamber study. Metal activities were determined with GEOCHEM. The mineral phases believed to be governing Al³⁺ activities were jurbanite under low pH conditions and amorphous Al(OH)₃ at high pH. The Al chemistry is believed to be intimately linked to the redox-pH cycle, which is driven by the monsoonal climate. Mortality of rice associated with Al toxicity was observed under field and growth chamber conditions. Interference in P uptake and/or assimilation was believed to be the mechanism of Al toxicity. Activities of B(OH) ₄ ^– and B(OH) ₃ ⁰ were found to be highly correlated to pH and ionic strength, respectively, with the latter being the dominant B ion found in these soils. Activities of MoO ₄ ^2– were positively correlated to pH and appeared to be controlled by wulfenite. Leaf Mo contents were found to be positively correlated with MoO ₄ ^2– activity.     

Xeric limestone prairies of eastern United States: Review and synthesis

Xeric limestone prairies (XLPs) are open, nonforested areas in which herbaceous plant communities occur on shallow, rocky soils derived from calcareous substrates. These grasslands are characterized by dominance of C₄ perennial grasses (particularlySchizachyrium scoparium) and are distributed in eastern United States from Missouri and Pennsylvania south to Arkansas and Georgia. XLPs occur in the Ozark Plateaus, Central Lowland, Interior Low Plateaus, Appalachian Plateaus, Ridge and Valley, and Coastal Plain physiographic provinces, and they are developed on Alfisols, Ultisols, Mollisols, Inceptisols, and Vertisols derived from Paleozoic limestones (also Eocene), dolomites, and calcareous shales. The C₄ perennial prairie grassS. scoparium is the characteristic dominant taxon in XLPs of eastern United States. However, C₃ perennial forbs are dominant in some sites, and C₄ annual grasses (Sporobolus spp.) may be locally dominant in shallow-soil-zone microsites. Thirteen taxa apparently are endemic, or nearly so, to this vegetation type, including eight in the Ridge and Valley in Alabama (Cahaba River valley), four in the Ozark Plateaus in Missouri and Arkansas, and one in the Ridge and Valley of West Virginia and Virginia. Various types of information are used to construct a conceptual model of the origin, maintenance, and successional dynamics of XLPs. Affinities of XLPs in eastern United States to other herbaceous vegetation types in eastern and western North America are discussed, and directions for future research are suggested.