Canopy gaps in an old-growth fir-beech forest remnant of Western Carpathians

The old-growth forest remnants of Western Carpathians provide a unique possibility to study the disturbance regimes of forest ecosystems without human influence. This study investigated the gap dynamics in beech-dominated old-growth forest Badínsky prales in Central Slovakia. Considering the decline of silver fir in last decades, the study analyzed the main characteristics of disturbance regime with the emphasis on the role of fir. On a 5-ha research plot, the dominant tree species was beech, the proportion of fir reached about 10%. However, a significantly higher proportion of fir (>30%) was observed in the coarse woody debris. In total, 45 canopy openings were recorded. Canopy gaps and expanded gaps covered 11.3 and 37.9% of the forest area, respectively. Despite the highest frequency of small gaps <100 m², their proportion of the overall gap area reached only 20%, what suggests the important role of intermediate and large gaps in the gap dynamics as well. The analysis of gapmakers’ crown projections confirmed a rather low contribution of fir (14.6%) to the gap formation despite its relatively intensive mortality. A high variability of the next generation age between the gaps (6–44 years) was recorded what suggests a large temporal variation of the disturbance events. The lateral expansion of adjacent trees was found to be the determining process for the closure of small canopy openings. The intermediate and large gaps are more likely closed by the height growth of natural regeneration and understory trees that are present on the majority of the area.     

Two new species of isospora (Apicomplexa: Eimeriidae) from geckoes of the genus Rhacodactylus (Sauria: Gekkonidae) endemic to New Caledonia

Coprological examination of New Caledonian geckoes of the genus Rhacodactylus Fitzinger, 1843 revealed two new species of coccidia. Isospora leachiani sp. n. from R. leachianus (Cuvier, 1829) has oval, colourless oocysts, measuring 21-26 x 16-18.5 microm. Sporocysts are ellipsoidal, 11-12.5 x 6.5-8 microm, with distinct Stieda and substieda bodies. Oocysts of Isospora sykorai sp. n. from R. ciliatus (Guichenot, 1866) are elongately oval to cylindrical, 20-23.5 x 11-14 microm; sporocysts of this species are ellipsoidal, 10-11.5 x 7-8 microm, with a slightly pointed end and Stieda and substieda bodies. Infected geckoes did not exhibit any alteration of their health status.     

Differentiation of Actinobacillus pleuropneumoniae by PCR-REA based on sequence variability of the apxIVA gene and by ribotyping

During the period of 2001-2003, a total of 591 Actinobacillus pleuropneumoniae field isolates from the Czech Republic were serotyped with a high occurrence of cross-reactions. The cross-reactions were observed in 416 isolates. Most frequently, in 401 isolates (67.9%), cross-reactions with antisera specific for serotypes 9, 11, and/or 1 were observed. Two additional molecular methods, ribotyping and restriction analysis of PCR amplified apxIVA gene (PCR-REA), were therefore used for detailed characterisation of A. pleuropneumoniae. In this subsequent analysis, reference strains representing serotypes 1-12 and 25 field isolates showing the most frequent serotype cross-reactions were examined. PCR-REA enabled all reference strains to be distinguished except for the strains of serotypes 9 and 11. Ribotyping distinguished all reference strains except two pairs of serotypes: 3 versus 6, and 9 versus 11, respectively. Field isolates with serotype cross-reactivity 9, 11, and/or 1 could not be differentiated by either of these methods.     

Measurement of total antioxidant capacity in gingival crevicular fluid and serum in dogs with periodontal disease

OBJECTIVE: To determine whether gingival crevicular fluid (GCF) and serum total antioxidant capacities (TACs) correlate with the degree of severity of periodontal disease in dogs. ANIMALS: 41 Toy and Miniature Poodles. PROCEDURES: After assessment of the degree of severity of naturally occurring periodontitis, GCF samples from both maxillary fourth premolars and a blood sample were collected from each dog. The condition of the periodontium of the entire dentition and at each site of GCF collection was recorded. Clinical parameters assessed included plaque index, gingival index, and probing depth. Radiographic analysis of alveolar bone level was also performed. Total antioxidant capacity was measured in GCF and serum samples by use of a commercial kit. RESULTS: Dogs with gingivitis and minimal periodontitis had significantly higher TAC in GCF than dogs with advanced periodontitis. Bivariate regression analysis revealed significant negative correlations between TAC in GCF and clinical parameters and age. The TAC in serum was significantly negatively correlated with the degree of gingival inflammation but was not significantly correlated with age. CONCLUSIONS AND CLINICAL RELEVANCE: TAC in GCF is related to the degree of severity of periodontal disease in dogs. This is likely the result of release of reactive oxygen species by activated phagocytes and fibroblasts in the inflamed periodontal tissues. The results of our study suggest that the local delivery of antioxidants may be a useful adjunctive treatment for periodontitis in dogs.     

Linearity of eprinomectin pharmacokinetics in lactating dairy sheep following pour-on administration: excretion in milk and exposure of suckling lambs

Pharmacokinetics of eprinomectin (EPR) were studied in blood plasma and milk in two groups of six Istrian Pramenka dairy sheep and their suckling lambs following pour-on administration of EPR to ewes at dose levels of 0.5 and 1 mg/kg. Maximum concentration in plasma was 2.22 and 5.25 μg/l, and AUC was 13.6 and 33.7 μg day/l for the 0.5 and 1.0 mg/kg dose, respectively. These results indicate that drug exposure with a dose of 0.5 mg/kg, which is commonly used in cattle, may be subtherapeutic. The concentration time course in milk paralleled plasma concentrations. In the dose range studied, linear pharmacokinetics of EPR were demonstrated. Milk-to-plasma AUC ratio was 0.79 ± 0.12 and 1.12 ± 0.43; the fraction of dose recovered in milk was 0.037 ± 0.011 and 0.058 ± 0.027% for the low and high dose, respectively. Maximum residual levels in milk were below the maximum acceptable level of 20 μg/kg; however, EPR was detected in all samples investigated. Despite low permeability in milk, AUC in plasma of suckling lambs was between 20 and 30% of the AUC in plasma of ewes.     

Temporal and spatial distribution of glochidial larval stages of European unionid mussels (Mollusca: Unionidae) on host fishes

Glochidia are the larval stage of freshwater unionid mussels that parasitize the fins and gill apparatus of fish. A total of 22 fish species were examined for the presence of glochidia whose distribution on individual hosts was studied on three common fish species, the roach Rutilus rutilus (L.), perch Percafluviatilis L. and bitterling Rhodeus sericeus (Pallas). Between 1997 and 1999, the fish were obtained from the rivers Morava and Kyjovka and surrounding water pools in the Czech Republic. The glochidia of two genera, Unio and Anodonta, were found. Anodonta glochidia were observed on 10 fish species, Unio glochidia on 17 fish species. There was a difference in spatial distribution of glochidia on the body of the host fish. Unio glochidia were predominantly located on the gills, whereas most Anodonta glochidia were found on the fins, with the highest numbers of glochidia were observed on the margin of the pectoral fins. For the gill apparatus, Unio glochidia were found predominantly on the second and third arch. Anodonta glochidia were predominantly found during winter and spring (November-May), whereas Unio glochidia were more abundant during May and June. The number of glochidia was positively correlated with fish length in perch highly infected by Anodonta glochidia and perch infected by Unio glochidia. Of the three fish species, the highest occurrence of parasites was found on perch with fewer observed on roach. In spite of the close relationship between bitterling and unionid mussels, glochidiosis was rare on this fish species.     

Dynamics of storm-driven suspended sediments in a headwater catchment described by multivariable modeling

Purpose  

Previous research has shown that the rate at which suspended sediment is transported in watercourses depends primarily on discharge (Q) as the first-order control, but additional factors are thought to affect suspended sediment concentrations (SSC) as well. Among these, antecedent hydrological and meteorological conditions (e.g., rainfall depth and intensity, discharge prior to a runoff event and the duration of runoff events) may represent significant transport controlling mechanisms. Univariate models using Q–SSC rating curves often produce large scatter and nonlinearity, because many of the hydrological and biotic processes affecting the dynamics of sediment are non-linear and exhibit threshold behavior. The simulation of such highly non-linear processes is therefore an elusive task requiring consideration of several interrelated controlling variables. The aim of this study was to identify the major hydrological and meteorological controls determining the dynamics of SSC during storm-runoff events and the magnitude of SSC in a headwater catchment in Luxembourg.     

Identification and characterization of Agrobacterium spp. isolated from apricot in Serbia

Crown gall, caused by tumorigenic strains of Agrobacterium spp., is considered one of the most important diseases in stone fruit nurseries throughout the world. Since the crown gall disease has not been studied extensively in Serbia for more than 30 years, the objective of this study was to isolate, identify and characterize the bacterium associated with crown gall symptoms on one-year-old apricot trees. Samples were collected from a nursery in central Serbia and subjected to laboratory analysis. Bacteria were isolated from tumour tissue on yeast mannitol agar (YMA) and six gram-negative isolates were selected for further study. PCR assay using primers specific for virD2, virC, ipt and tms2 pathogenicity-associated plasmid genes revealed that isolates harbour Ti plasmids. All studied strains carrying Ti plasmids were classified as nopaline-type based on further molecular analysis. Using a multiplex PCR assay, targeting 23S rRNA gene sequences, and physiological and biochemical tests, five strains were assigned as A. rhizogenes/biovar 2 and the remaining one as A. tumefaciens/biovar 1. Identity of the strains was confirmed by sequence analysis of the 16S rRNA gene. In pathogenicity assay, all six strains caused tumour formation on inoculated carrot root discs, young tomato and sunflower plants.     

Variation in the mortality rate of turkeys during transport to the slaughterhouse with travel distance and month

Failure to comply with animal welfare requirements during the transport of turkeys to the slaughterhouse increases stress in animals, which is manifested by increased mortality rate during transport. The numbers of turkeys that died during transport or soon after arrival may serve as an important parameter to indicate the level of animal welfare during transport of turkeys. The number of turkeys that died during transport to slaughterhouses in the Czech Republic in the period from 1997 to 2004 was investigated. The mortality rate found was 0.28% +/- 0.06% but varied with travel distance. The lowest mortality rate was found in case of travel distance below 50 km (0.18% +/- 0.08%) while long travel distances resulted in considerable increase in the mortality rates of turkeys (between 0.28% +/- 0.07 and 0.37% +/- 0.10%). The mortality rate of transported turkeys was also affected by the particular month of the year. Thus, the highest overall mortality rate occurred at long travel distances during winter months, i.e. in December (0.34% +/- 0.18%), January (0.32% +/- 0.06%), and February (0.36% +/- 0.07%). The comparison of individual years has shown a long-term trend towards a decrease in turkeys' mortality during transportation to slaughterhouses from 0.32% in 1998 to 0.20% in 2004. The decrease was statistically significant (Spearman's rank correlation coefficient r = -0.86, p < 0.01). This trend can be evaluated as positive.