Improved method for comparing abundance data for soil zoological field studies

Soil bulk density varies among sites as well as microhabitats, and in different years at the same site. Bulk density is a highly variable parameter that introduces undefined but significant errors to abundance field data of soil microfauna when given in individuals per g soil dry mass (sdm). Such data are not comparable among sites, microhabitats and years and they are unsuitable for comparative ecological field studies. Soil corer sampling technique, defined as soil surface square units (e.g. 1 cm²), is recommended to overcome the methodological imprecision of estimating abundance of soil microfauna from field studies in ind·g sdm. This removes consideration of variable soil bulk density and enables us to establish abundance values directly in ind·cm⁻² without any recalculations. Resultant data are comparable both spatially and temporally. Abundance data as individuals per m² is a commonly used unit for soil meso-, macro- and megafauna.

Résumé

La densité apparente du sol est extrêmement variable aussi bien selon les sites que selon les microhabitats, ainsi que selon les différentes années sur un même site. La variabilité de ce paramètre induit des erreurs mal définies, mais significatives, dans l'estimation des abondances de la microfaune du sol lorsque celles-ci sont produites en termes de nombre d'individus par gramme de sol sec. De telles données ne sont pas comparables entre sites, microhabitats, ou années, et ne sont donc pas utilisables pour des études d'écologie comparative. La méthode d'échantillonnage par carottage du sol sur une surface connue (par exemple 1 cm²) est recommandée afin de maîtriser l'imprécision liée aux estimations par poids de sol sec. Cela permet de s'affranchir du paramètre de densité apparente du sol et permet de donner directement des valeurs d'abondance en nombre d'individus par cm² sans aucun calcul. Les données ainsi exprimées sont comparables, à la fois spatialement et temporellement. Le nombre d'individus par m² est une unité communément utilisée pour la méso-, macro- et mégafaune.     

Regional Contamination of Moravia (South-Eastern Czech Republic): Temporal Shift of Pb and Zn Loading in Fluvial Sediments

Regional contamination by Pb and Zn in southern Moravia (south-east part of the Czech Republic) in the twentieth century was analysed in Brno Dam lake sediments and in floodplain sediments of the Morava River near Strážnice. The age model for the Brno Dam lake sediments has been obtained by ¹³⁷Cs (maxima corresponding to the nuclear tests in atmosphere and the 1986 Chernobyl accident) and the construction of the dam (1940); the time constraints for the Morava River sediments was the erection of flood defences (1930s) and ²¹⁰Pb dating. In the case of floodplain sediments, profiles exhibiting post-depositional mobilisation of heavy metals by pedogenic processes (gleying) must be excluded to reconstruct the history of contamination. There was a relatively fast joint onset of Pb and Zn load since the early stages of industrialisation in the first half of the twentieth century, but then the concentrations of these two metals developed in a different manner. Pb load only slightly increased till its peak in 1960s and 1970s. The increase of Zn load was rather stepwise: Soon before 1930s (Morava River floodplain) and in 1940s and 1950s (in Brno Lake), the relative contamination by Zn was much lower than during its peak in the 1970s to the present days. The offset of Pb and Zn contamination curves could have been caused by three different artificial sources of these heavy metals. The temporal shift of Pb and Zn loads can be used for dating sediments.     

Genetic analysis of resistance in barley to barley yellow dwarf virus

The inheritance of resistance to barley yellow dwarf virus (BYDV) was studied in the selected 24 spring and winter barley cultivars that showed a high or intermediate resistance level in 1994‐97 field infection tests. The polymerase chain reaction diagnostic markers YLM and Ylp were used to identify the resistance gene Yd2. The presence of the Yd2 gene was detected with both markers in all the resistant spring barley cultivars and lines from the CIMMYT/ICARDA BYDV nurseries. The results of field tests and genetic analyses in winter barley corresponded with marker analyses only when the Ylp marker was used. Genes non‐allelic with Yd2 were detected by genetic analyses and the Ylp marker in moderately resistant spring barley cultivars ‘Malvaz’, ‘Atribut’ and ‘Madras’, and in the winter barley cultivars ‘Perry’ and ‘Sigra’. Significant levels of resistance to BYDV were obtained by combining the resistance gene Yd2 with genes detected in moderately resistant cultivars. The utilization of analysed resistance sources in barley breeding is discussed.     

Radial velocity profiles of water flow in trunks of Norway spruce and oak and the response of spruce to severing

Trunk-tissue heat balance, volumetric and staining methods were used to study xylem water flow rates and pathways in mature Norway spruce (Picea abies (L.) Karst.) and pedunculate oak (Quercus robur L.) trees. The radial profile of flow velocity was confirmed to be symmetrical in spruce, i.e., maximum flow velocity was in the center of the conducting xylem and tailed with low amplitude (about 30 cm h(-1)) in the direction of the cambium and heartwood. Variability around the trunk was high. In contrast, in oak, the radial profile of flow velocity was highly asymmetrical, reaching a peak of about 45 m h(-1) in the youngest growth ring and tailing centripetally for about 10 rings, but variability around the trunk was less, under non-limiting soil water conditions, than in spruce. In spruce, the flow rate increased abruptly within seconds when the tree was severed while immersed in water, and then decreased gradually, showing significant root resistance. We conclude that water flow through an absorbing cut surface differs from the flow higher in a tree trunk because of the presence of hydraulic capacitances in the conductive pathways. The staining technique always yielded higher estimates of flow velocity than the non-destructive tree-trunk heat balance method.     

Effect of medetomidine-butorphanol and dexmedetomidine-butorphanol combinations on intraocular pressure in healthy dogs

ObjectiveTo assess the effects of intravenous (IV) medetomidine-butorphanol and IV dexmedetomidine-butorphanol on intraocular pressure (IOP).Study designProspective, randomized, blinded clinical study.AnimalsForty healthy dogs. Mean ± SD body mass 37.6 ± 6.6 kg and age 1.9 ± 1.3 years.MethodsDogs were allocated randomly to receive an IV combination of dexmedetomidine, 0.3 mg m^?2, combined with butorphanol, 6 mg m^?2, (group DEX) or medetomidine 0.3 mg m^?2, combined with butorphanol 6 mg m^?2, (group MED). IOP and pulse (PR) and respiratory (f_R) rates were measured prior to (baseline) and at 10 (T10), 20 (T20), 30 (T30) and 40 (T40) minutes after drug administration. Oxygen saturation of hemoglobin (SpO₂) was monitored following sedation. Data were analyzed by anova followed by Dunnett's tests for multiple comparisons. Changes were considered significant when p < 0.05.ResultsFollowing drug administration, PR and f_R were decreased significantly at all time points but did not differ significantly between groups. Baseline IOP in mmHg was 14 ± 2 for DEX and 13 ± 2 for MED. With both treatments, at T10, IOP increased significantly (p < 0.001), reaching 20 ± 3 and 17 ± 2 for DEX and MED respectively. This value for DEX was significantly higher than for MED. There were no significant differences in IOP values between groups at any other time points. At T30 and T40, IOP in both groups was below baseline (DEX, 12 ± 2 and 11 ± 2: MED 12 ± 2 and 11 ± 2) and this was statistically significant, for DEX.Conclusions and clinical relevanceAt the documented doses, both sedative combinations induced a transient increase and subsequent decrease of IOP relative to baseline, which must be taken into consideration when planning sedation of animals in which marked changes in IOP would be undesirable.     

Structure of the Cochliobolus sativus population variability

The genetic diversity of several local populations of the fungal pathogen Cochliobolus sativus, collected over 3 years from different regions of the Czech Republic, was examined using amplified fragment length polymorphism (AFLP). A high level of variability was found even among isolates from one lesion. Measures of multilocus linkage disequilibrium suggested that recombination has a minor impact on the genetic structure of populations. Cochliobolus sativus forms genetically divergent populations (F_ST = 0·33), indicating a low level of geneflow between populations. This was supported by a significant correlation between genetic diversity and geographical distances up to 80–100 km. The most likely explanation for the genetic variability is that the fungus forms conidia with highly variable chromosomal rearrangements. The differentiation observed among local populations implies that genetic drift, including a founder effect, combined with restricted migration generates the structure of C. sativus populations.     

Considering landscape connectivity and gene flow in the Anthropocene using complementary landscape genetics and habitat modelling approaches

Landscape Ecology - A comprehensive understanding of how rapidly changing environments affect species gene flow is critical for mitigating future biodiversity losses. While recent methodological...     

Studies on the antigenicity of an inactivated, aluminum hydroxide adjuvant equine influenza vaccine.

An inactivated, aluminum hydroxide adjuvant equine influenza vaccine was tested in horses and guinea pigs to determine the levels of antigen that would elicit maximum serological responses. Vaccine containing serial twofold increments of A/Equi-1/Prague and A/Equi-2/Miami strains of equine influenza virus was administered to random groupings of both types of test animals. The hemagglutination inhibition antibody response for each group was then measured. Results in horses and guinea pigs were compared to determine if the equine serological values could be related to a potency test in laboratory animals. The highest mean hemagglutination inhibition antibody response in horses occurred in groups vaccinated, respectively, with 128 or 256 hemagglutination units of A/Equi-1 and 512 or 1024 hemagglutination units of A/Equi-2 antigen. Groups vaccinated with further two- or fourfold increases in these antigens had mean hemagglutination inhibition titers that were somewhat lower than the maximum levels. When graded doses of vaccine were given to guinea pigs, their hemagglutination inhibition antibody titers reached a plateau of maximum values, similar to the serological response in vaccinated horses. Test horses remained clinically free from signs of equine influenza during the year following vaccination and no untoward post-vaccination reactions were observed.