Collagen fiber architecture of the periodontal ligament in equine cheek teeth

The objective of this study was to examine the spatial arrangement of the fiber apparatus of the equine periodontium which is supposed to meet two contrary requirements: (1) to attach the tooth firmly and elastically to the alveolar bone; and, to be appropriately remodeled and reconstructed in order to facilitate the prolonged eruption of the tooth. Specimens of periodontal ligament were obtained from the buccal and lingual/palatal aspects of the first molars from the maxilla and mandible of 12 horses. The animals were assigned to three age groups. Histological sections were prepared from three specific horizontal levels of the periodontal ligament and examined with conventional and polarized-light microscopy. At the gingival level, collagen fascicles (diameter > 200 microm) were densely packed. Their spatial alignment was the same in all age groups. The architecture of the collagen fiber apparatus differed at the middle and apical levels in the three age groups. There was a clear distinction between fibers, bundles, and fascicles. Bundling of collagen fibers, density of the fiber arrangement, and collagen fascicles with an alveolo-cemental orientation increased with age. The collagen fiber apparatus of the equine periodontal ligament is highly adaptive, responding continuously to the dynamic changes in the periodontal environment. Site-specific arrangements and age-dependent structural variations are assumed to maintain tooth support as the reserve crown gradually decreases in length with progressive dental attrition. Most of the age-dependent changes to the periodontal ligament in teeth examined in this study occurred at the apical level. The apical region of young teeth had no periodontal attachment, while the roots of older teeth were firmly attached to the alveolus. When evaluating periodontal ligament development, the individual tooth's 'dental age' should be considered rather than the animal's age to account for individual tooth eruption times.     

Detection of Mycobacterium avium ssp. paratuberculosis in ileocaecal lymph nodes collected from elderly slaughter cows using a semi-nested IS900 polymerase chain reaction

The aim of this study was to investigate the occurrence of subclinical Mycobacterium avium spp. paratuberculosis (MAP) infections at slaughter by testing ileocaecal lymph nodes with a semi-nested IS900 PCR. Tissue samples were available within the framework of a parallel study investigating BSE-susceptibility factors in members of BSE-cohorts in the German Federal State of Lower Saxony. Ileocaecal lymph nodes were collected over a 2-year sampling period from 99 slaughter cattle of a mean age of 6.5 years (5.5-7.5 years). A recently developed IS900 semi-nested polymerase chain reaction (snPCR) assay offering a sensitivity of 1 genome equivalent was used for the detection of MAP-DNA. Based on this snPCR, 17 out of the 99 samples gave positive results, indicating a MAP occurrence of 17.17% in the random sample. All PCR products were sequenced for screening of polymorphisms. Nucleotide homologies of 98.5-100% were found with respect to the MAP K10 reference sequence IS900 (GenBank: AE16958). PCR analysis of ileocaecal lymph nodes collected from slaughter cattle proved to be a suitable technique to determine MAP occurrence in the local cattle population.     

How landscape,pollen intake and pollen quality affect colony growth in <Emphasis Type="Italic">Bombus terrestris</Emphasis>

Context

Abundance and diversity of bumblebees have been declining over the past decades. To successfully conserve bumblebee populations, we need to understand how landscape characteristics affect the quantity and quality of floral resources collected by colonies and subsequently colony performance.

Objectives

We therefore investigated how amount and composition of pollen collected by buff-tailed bumblebee Bombus terrestris colonies was affected by the surrounding landscape (i.e. the proportion of forest, urban, semi-natural habitats) and how they were related to colony growth.

Methods

Thirty B. terrestris colonies were placed at grassland sites differing in surrounding landscape. Colonies were established in spring when availability of flowering plants was highest, and their weight gain was monitored for 1 month. We additionally recorded the quantity and compared plant taxonomic composition and nutritional quality (i.e. amino acid composition) of pollen stored.

Results

Bumblebee colonies varied little in the pollen spectra collected despite differences in surrounding landscape composition. They collected on average 80 % of pollen from woody plants, with 34 % belonging to the genus Acer. Early colony growth positively correlated with total amount of woody pollen and protein collected and decreased with increasing proportions of semi-natural habitats and total amino acid concentrations.

Conclusions

Our results suggest that woody plant species represent highly important pollen sources for the generalist forager B. terrestris early in the season. We further show that colony growth of B. terrestris is predominantly affected by the quantity, not quality, of forage, indicating that several abundant plant species flowering throughout the bumblebees’ foraging season may cover the colonies’ nutritional needs.

     

Verteilung und Ausbreitung der epigäischen Arthropoden in der Agrarlandschaft I. Carabidae

Zusammenfassung Im Jahre 1978 wurde die Carabiden-Fauna eines Maisfeldes und eines angrenzenden Winterroggenfeldes untersucht. Das Maisfeld war durch eine geringere Arten- und Individuenzahl und einen niedrigeren Diversitätswert (H_s=2,46) als das Winterroggenfeld (H_s=3,05) gekennzeichnet. Die Unterschiede ließen sich jedoch nicht auf den unmittelbaren Einfluß der pestizidbehandlung (Gesaprim) zurückführen. Auf dem Maisfeld fehlten viele der frühjahrsaktiven, konstant makropteren und flugfähigen Arten der GattungAmara. Hingegen überwogen in ihm die herbstaktiven Arten mit Flügeldimorphismus wiePterostichus melanarius, Calathus melanocephalus undC. fuscipes. Es sind Arten, die durch Kulturmaßnahmen im Vergleich zu den anderen Laufkäfern nur wenig geschädigt wurden und als synanthrop gelten können. Am Beispiel vonC. melanocephalus wurde deutlich, daß jährlich etwa 8–9% aller Individuen einer Population in die Felder einwanderten.

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Distribution and dispersal of epigeic arthropods in agroecosystems I. Carabidae

Observations on Carabid populations were made in neighbouring maize- and ryefields. Individual- and species richness was lower in the maize (H₅=2.46) than in the rye (H_s=3.05). Pauperisation of the fauna in the maizefield was not directly due to pesticides. In the rye-field many of the springbreeders and the monomorphic macropterous species with high dispersal power (Amara spp.) were characteristic. In contrast the dominant species of populations e. g.Pterostichus melanarius, Calathus melanocephalus andC. fuscipes. Their sensitivity against agricultural practices is much lower and they are at least to some extent synantropic. The annual immigration ofC. melanocephalus into the fields amounts to 8–9% of its total population.

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Mit 5 Abbildungen und 3 Tabellen     

Detergents modify proteinase K resistance of PrP Sc in different transmissible spongiform encephalopathies (TSEs)

Prion diseases are diagnosed by the detection of their proteinase K-resistant prion protein fragment (PrP(Sc)). Various biochemical protocols use different detergents for the tissue preparation. We found that the resistance of PrP(Sc) against proteinase K may vary strongly with the detergent used. In our study, we investigated the influence of the most commonly used detergents on eight different TSE agents derived from different species and distinct prion disease forms. For a high throughput we used a membrane adsorption assay to detect small amounts of prion aggregates, as well as Western blotting. Tissue lysates were prepared using DOC, SLS, SDS or Triton X-100 in different concentrations and these were digested with various amounts of proteinase K. Detergents are able to enhance or diminish the detectability of PrP(Sc) after proteinase K digestion. Depending on the kind of detergent, its concentration - but also on the host species that developed the TSE and the disease form or prion type - the detectability of PrP(Sc) can be very different. The results obtained here may be helpful during the development or improvement of a PrP(Sc) detection method and they point towards a detergent effect that can be additionally used for decontamination purposes. A plausible explanation for the detergent effects described in this article could be an interaction with the lipids associated with PrP(Sc) that may stabilize the aggregates.     

Seasonal effects of habitat structure and weather on the habitat selection and home range size of a mammal in agricultural landscapes

Landscape Ecology - Human land use intensified over the last century and simultaneously, extreme weather events have become more frequent. However, little is known about the interplay between...     

Investigations on the water intake of growing bulls

The voluntary water intake was evaluated in 62 growing Holstein bulls (mean body weight range = 193 to 550 kg) during a whole fattening period. The diet was composed of corn silage and concentrates. Water was offered for ad libitum consumption. A total of 17,772 measurements of water intake were recorded over 282 days. The average daily water consumption was 18 kg/animal (S.D. = 6.7 kg). Applying a multiple regression analysis to the data set yielded the following equation: voluntary water intake (kg/day) = − 3.85 + 0.507  average ambient temperature (°C) + 1.494  dry matter intake (kg/day) − 0.141  roughage part of the diet (%) + 0.248  dry matter content of roughage (%) + 0.014  body weight (kg). The incorporation of the variables body weight gain, relative humidity, maximum ambient temperature, Na intake, and K intake into the equation did not increase the accuracy of the prediction.     

Analysis of the free range behaviour of laying hens and the genetic and phenotypic relationships with laying performance

1. Over twelve 28-d laying periods (almost one year), 272 laying hens of the Lohmann Silver strain, individually tagged with transponders, were monitored on their ranging behaviour and laying performance in an aviary system with an adjacent winter garden. 2. From laying periods 1 to 12, the daily frequency of passages between the barn and the winter garden of individual hens, showed an antagonistic trend compared to the average duration of single visits. While the frequency of passages decreased until the end of the recording period to 8 passages per hen and day, the average duration of single visits increased to a maximum of 32 min per hen. 3. The heritability estimates for the traits, length of stay in the winter garden and frequency of passages were higher for the last 5 laying periods than at the beginning of the recording period. For the last 5 laying periods, the estimates for the duration of stay in the winter garden varied between h(2) = 0.21 and 0.32 and for the frequency of passages, between h(2) = 0.30 and 0.49. 4. Most of the estimated heritabilities for the rate of lay were on an expected medium level (h(2) = 0.09 to 0.45). Deviant h(2)-values to a few laying periods were based on low additive genetic variances or high environmental variance. 5. Genetic correlations between both free range traits and the laying performance were negative (r(g length of stay) = -0.34 and r(g passage frequency) = -0.08). 6. Generally, there seems to be a possibility to influence the ranging behaviour through selection. Further investigations with different genotypes and varying dates of exposure to the laying environment, should be carried out to clarify possible influences on other traits and the negative correlation with laying performance.     

Implications of genetic selection on yolk proportion on the dry matter content of eggs in a White Leghorn population

1. The responses to genetic selection on yolk proportion as a technique for increasing egg dry matter content, an important criterion for the egg-product industry, was investigated in a pedigree flock of White Leghorn hens.

2. Parents were preselected on high and low yolk proportion from a base population. The absolute estimated breeding value for yolk proportion of both groups differed by 3%. The realised selection difference in dry matter content of eggs between groups was more than 1% in the analysed offspring population.

3. Heritability estimates were moderate and dry matter had a lower heritability (h² = 0.39) than yolk proportion (h² = 0.44).

4. The genetic correlation between yolk proportion and dry matter content was highly positive (r_g = 0.91). Genetic correlations with egg weight were negative and would have to be compensated for in a breeding programme (r_g = ?0.76 with yolk proportion and r_g = ?0.64 with dry matter content). The genetic correlation between the laying performance and yolk proportion was r_g = 0.28 and close to zero (r_g = ?0.05) for dry matter content.

5. Easy recording and lower undesirable correlations make yolk proportion more suitable for commercial selection compared with egg dry matter content in layer breeding.