Apoplast acidification is not a necessary determinant for the resistance of maize in the first phase of salt stress

In previous studies, a relation between plant growth during the first phase of salt stress and cell‐wall acidification was shown for differently resistant maize genotypes. In the present study, plants of the salt‐sensitive maize (Zea mays L.) cv. Pioneer 3906 and the salt‐resistant genotype SR 12, grown under 100 mM NaCl, showed a similar decrease in plasmalemma H⁺‐ATPase activity, while SR 12 showed less growth reduction than Pioneer 3906. From this it is concluded that maintenance of apoplast acidification is not necessary for better plant growth during the first phase of salt stress.     

Geochemical analysis of Lake Bant sediments to ascertain inorganic and organic indicators for warfare residues

Purpose  

The immediate time period after the Second World War (1945–1946) was characterised by an urgent need to dispose large amounts of ammunition residues. Although the environmental relevance of explosives released to soils is intensively investigated, to date, their fate and effects in marine ecosystems are not well known. Surface sediments from Lake Bant, Germany, for which deposition of an enhanced amount of ammunition after World War II has been reported, were analysed to identify organic and inorganic indicators for warfare residues. Additionally, samples of ammunition residues collected from the Wadden Sea, Germany, were analysed in order to obtain information on the long-term behaviour of explosives in undamaged ammunition left in the aquatic environment and to obtain first insights into the spectrum of organic substances which are possibly released to the aquatic environment by such ammunition residues.     

High-speed cinematographic evaluation of claw-ground contact pattern of lactating cows

To evaluate the manner in which a cow's claws make contact with the ground at the walk, the gait, and in particular the claw-ground contact pattern, were studied in 12 healthy, lactating dairy cows, using high-speed cinematography (500frames/s) while the animals were walking on a treadmill. The results showed that the limbs were advanced around the contralateral limbs in a sigmoid curve. The feet contacted the ground with the foot axis and the tips of the claws rotated slightly outwards. In all cows the lateral claws contacted the ground before the medial claws in the hindlimbs, and in 10/12 cows in the forelimbs. The heel of the lateral claws was the region of initial contact with the ground in the hindlimbs of all cows and in the forelimbs in 9/12 cows. Lateral 'heel first' contact in the fore and hindlimbs appeared to be the normal gait pattern in these animals. Compared with a previous study of heifers, lactating cows had a larger step width in the hindlimbs and a smaller step width in the forelimbs. These ground contact patterns offer an explanation for the predisposition to claw disorders of the lateral claw of the hindlimb. The results of this study reinforce the suggestion that soft floor surfaces should be provided for cattle to prevent mechanical injury to the claws.     

A rapid, sensitive, and cost-efficient assay to estimate viability of potato cyst nematodes

Potato cyst nematodes (PCNs) are quarantine organisms, and they belong to the economically most relevant pathogens of potato worldwide. Methodologies to assess the viability of their cysts, which can contain 200 to 500 eggs protected by the hardened cuticle of a dead female, are either time and labor intensive or lack robustness. We present a robust and cost-efficient viability assay based on loss of membrane integrity upon death. This assay uses trehalose, a disaccharide present at a high concentration in the perivitelline fluid of PCN eggs, as a viability marker. Although this assay can detect a single viable egg, the limit of detection for regular field samples was higher, ≈10 viable eggs, due to background signals produced by other soil components. On the basis of 30 nonviable PCN samples from The Netherlands, a threshold level was defined (ΔA(trehalose) = 0.0094) below which the presence of >10 viable eggs is highly unlikely (true for ≈99.7% of the observations). This assay can easily be combined with a subsequent DNA-based species determination. The presence of trehalose is a general phenomenon among cyst nematodes; therefore, this method can probably be used for (for example) soybean, sugar beet, and cereal cyst nematodes as well.     

Host-gut microbiota metabolic interactions

The composition and activity of the gut microbiota codevelop with the host from birth and is subject to a complex interplay that depends on the host genome, nutrition, and life-style. The gut microbiota is involved in the regulation of multiple host metabolic pathways, giving rise to interactive host-microbiota metabolic, signaling, and immune-inflammatory axes that physiologically connect the gut, liver, muscle, and brain. A deeper understanding of these axes is a prerequisite for optimizing therapeutic strategies to manipulate the gut microbiota to combat disease and improve health.     

A Method for Determination of Tocopherol in Bovine Blood

A salt solution for stabilization of the tocopherols in plasma is introduced. A lenient method for extraction of lipids of this kind is described. The method of colorimetric determination according to Emmerie and Engel is modified in using a mixture of acetone, benzene and water. These substances do not interfere with the reaction components, thus, giving extinction values constant for hours, and allowing exact determinations of tocopherols. Corrections for carotenes are to be done and annotated.     

Somatic in vitro culture response of Lolium perenne L.: genetic effects and correlations with anther culture

Summary Genotypic effects on callus induction and plant regeneration in callus, suspension and protoplast culture, and their correlations with both phenotypic and GCA-values for anther culture response, were studied using 21 genotypes of perennial ryegrass. Differences between genotypes accounted for approximately 40% of the total variation for callus induction and initial callus growth, and 59 and 83% of the variation in callus culture for regeneration percentage and percentage of green plants. Effects of genotypes were less pronounced in suspension culture, where suspensions from the same genotype often behaved differently. Some suspension cultures retained their capacity for green plant regeneration for almost two years, repeatedly producing 80–100% green regenerants during this period. Genotypes with high regeneration percentage and a large proportion of green plants from callus culture were also superior in suspension culture for both regeneration performance and longevity. Regeneration percentage and percentage of green plants were uncorrelated, and probably under different genetic control. While capacity for green plant formation from the different genotypes showed no correlation between anther culture and somatic in vitro culture, a positive correlation was observed between the regeneration percentages in somatic in vitro culture and anther culture (r=0.44^*–0.85^***), suggesting some common genetic control of the two systems.     

Occurrence of nematodes, tardigrades and rotifers on ice-free areas in East Antarctica

Nematodes, rotifers and tardigrades were collected on three nunataks (mountain peaks penetrating the ice sheet) in Vestfjella, on six nunataks in Heimefrontfjella and on the Schirmacher Oasis in East Antarctica in the austral summers of 1996/97 and 2001/02. Most samples were taken on the nunatak Basen in Vestfjella where the Swedish station Wasa is located. The microfauna was patchily distributed and the highest densities of animals were found on sites with visible vegetation of mosses, lichens or algae. Thirty-four taxa of nematodes and tardigrades were found. Only seven of these occurred regularly in apparently actively reproducing populations. Other occasional records of nematodes had very few specimens. The highest number of species was found on the nunatak Basen. Rotifers, found in 66% of the samples, were the most frequent animal group. Nematodes occurred in 37% of the samples and tardigrades in 42%. The most frequent nematodes were Plectus and Panagrolaimus, occurring in 26% and 5% of the samples, respectively. Macrobiotus, Hebesuncus and Acutuncus were the most frequent and abundant tardigrades. The pattern of animal distribution can be related to both habitat characteristics and to the geographic position of the nunatak. The communities are little organised and the distribution of the fauna has similarities with an early phase of colonisation.     

A statistical approach to decompose ecological variation

As indicators of pollutant deposition, epiphytic algae on Norway spruce needles and lichens on Scots pine trunks were monitored at 15 sites over Sweden for 4 and 12 years, respectively. Pollutant deposition was measured simultaneously. The algae and lichens were strongly correlated to three groups of environmental factors namely geographical position, climate and pollutant deposition. Use of partial Redundancy Analysis (RDA) showed that the major part, 67%, of the total explained variation of algae was the joint effect of the three environmental factor groups. Climatic factors alone and the joint effects of S and N deposition and climate make up 13% and 12%, respectively. Pure geography and deposition accounted for less than 5% each. Also with lichens the main variation, 41%, was due to the joint effect of the three groups whereas 27% was due to pure geography and 14% to pure climate. Deposition alone and the joint effect of deposition and climate made up 5% and less. It suggests that the algae were mainly influenced by climate and deposition, and the lichens by climate and geographic position.     

Annual and long-term fluctuations of the nematode fauna in a Swedish Scots pine forest soil

Samples from an old Scots pine forest at Ivantjärnsheden in the middle of Sweden were used to study predictability and patterns of variation of soil nematode communities. There were two annual sampling series (1974–75 and 1977–78) and one long-term series sampled in September ten times over a period of 25 years. The abundance and the composition of the fauna fluctuated rather considerably in both the annual and long-term series. In the annual series abundance and species composition varied in a way which can partly be explained by changes in temperature and moisture. Total nematode abundance was influenced by soil water contents as indicated by co-variations with precipitation. Although the variations in abundance and fauna composition were large no systematic changes could be detected during 25 years. The differences in faunal structure between the two annual series were greater than between the annual and the long-term series.In all series there was a distinct vertical stratification of the fauna. In the superficial moss and litter layers species belonging to Adenophorea (Plectus) dominated. In deeper layers members of Rhabditida (Acrobeloides) contributed a greater proportion of the fauna. Variations of the annual series indicate that coexistence of different nematode species is facilitated by differences in response to temperature and moisture. The abundance of fungal and bacterial feeders changed in a regular way. During the summer the proportions of fungal and bacterial feeders were almost equal, but during the wet and cold winter the proportion of bacterial feeders increased. Rapidly growing bacterial feeding species belonging to Rhabditida were common in late summer and early autumn, whereas the more slowly growing bacterial feeders belonging to Adenophorea were most abundant during the winter. Although the community fluctuated rather much the average values indicated a rather high degree of predictability and also a high similarity with nematode faunas of other pine forest soils.