Floristic composition and spatial distribution of germinable seeds in a spruce plantation     

Miguel Alvarez  Katja Seis  Bodo Maria M?seler 《Annals of Forest Science》2012,69(5):557-567

Introduction

The logging of several spruce plantations is planned for the next years in the Eifel National Park (Western Germany). To understand the ecological mechanisms of spontaneous forest regeneration that follows these impacts, it is crucial to investigate the species composition and functional diversity of the buried germinable seeds in those stands.

Methods

We analysed the soil seed bank by germination method and characterised germination dynamics and distribution of seedlings throughout the samples according to a sigmoid model and cumulative curves, respectively. To compare the proportions of functional and syntaxonomical groups between seed bank and aboveground vegetation, we applied the Fisher??s exact test. Additionally, we described the spatial distribution of the species in the seed bank according to semivariograms.

Results

The studied seed bank reached a density of about 5,300 seed?m^?2. Most of the species detected in the seed bank are related to open vegetation, forest fringes and early successional stages of forest regeneration. In spite of a low floristic similarity between seed bank and aboveground vegetation, the functional and syntaxonomical composition is very similar. Further studies considering the distribution of seeds in the soil and the changes of the seed bank composition during the regeneration process are required.  相似文献   

Chemotherapy and radiation therapy in 4 dogs with muscle-invasive transitional cell carcinoma of the urinary tract     

Laura Marconato  Dagmar B. Nitzl  Katja J. Melzer-Ruess  Marcel A. Keller  Julia Buchholz 《The Canadian veterinary journal. La revue veterinaire canadienne》2012,53(8):875-879

Four dogs with T₂N₀M₀ transitional cell carcinoma of the lower urinary tract underwent multimodal treatment consisting of neoadjuvant chemotherapy, external-beam radiotherapy, and adjuvant chemotherapy. No significant toxicity was documented. All dogs showed clinical improvement and reduction of tumor volume based on computed tomography (CT).  相似文献   

Grazing of protozoa on rhizosphere bacteria alters growth and reproduction of Arabidopsis thaliana     

Kristin Krome  Katja Rosenberg  Michael Bonkowski  Stefan Scheu   《Soil biology & biochemistry》2009,41(9):1866-1873

Plant roots are densely colonized by bacteria which form the basis of the rhizosphere bacterial food web with protozoa as most effective predators. We established a well defined laboratory system with Arabidopsis thaliana as model plant allowing to investigate in detail the effect of rhizosphere interactions on plant performance. We used this system to analyse separate and combined effects of natural rhizobacteria and the protozoa Acanthamoeba castellanii on plants.Protozoa and bacteria increased plant growth with the effect of protozoa markedly exceeding that of bacteria only. Arabidopsis immediately responded to the presence of protozoa by increasing carbon but not nitrogen uptake. Later protozoa enhanced plant uptake of nitrogen from organic material and prolonged vegetative growth of Arabidopsis resulting in strongly increased seed production. It is concluded that the immediate plant response was based on changes in rhizosphere signalling inducing increased plant carbon fixation rather than on protozoa-mediated increase in nitrogen availability. The subsequently increased plant nitrogen uptake presumably originated from nitrogen fixed in bacterial biomass made available by protozoan grazing, i.e. the microbial loop in soil. The results suggest that Arabidopsis prepared for the upcoming mobilization of nitrogen by increasing carbon fixation and root carbon allocation which paid-off later by increased nutrient capture and strongly increased plant reproduction.  相似文献   

Top-down control of soil microarthropods - Evidence from a laboratory experiment     

Katja Schneider 《Soil biology & biochemistry》2009,41(1):170-175

Predator-prey interactions are of eminent importance as structuring forces for animal communities. The present study investigates if and how strongly the density of soil microarthropods is controlled by top-down forces, i.e. predation by mesostigmate mites (Mesostigmata, Acari). We set up a laboratory experiment running for ten weeks with undisturbed soil cores taken from the field using two densities of predatory mesostigmate mites: (1) ambient density (control) and (2) increased density (addition of seven Pergamasus septentrionalis and eight Lysigamasus sp. individuals). Increased predator density resulted in a decrease in the density of Oribatida, Collembola and Protura whereas the density of other taxa including Astigmata, Prostigmata and Uropodina was not significantly affected. Additionally, the species number of Oribatida was also not significantly affected. Taxa of Oribatida and Collembola were differently affected by increased predator density. Among Collembola, densities of Poduridae and Sminthuridae were reduced, whereas Entomobryidae were not affected. Among Oribatida, densities of Oppiidae and Suctobelbidae were reduced whereas Desmonomata, Poronota and Tectocepheus were not affected. Grouping of Oribatida into different size classes and into classes differing in sclerotization suggests that smaller mites (200-300 μm) and mites with less sclerotization were more heavily affected than larger mites and mites with strong sclerotization. The results indicate that predatory mesostigmate mites have the potential to control the density of certain taxa of soil microarthropods. In particular, small and little sclerotized prey is susceptible to predator control indicating that predator defense is an important component of the life history tactics of soil microarthropods, especially of Oribatida.  相似文献   

Diversity studies in genetic resources of <Emphasis Type="Italic">Solanum</Emphasis> spp. (section Petota) by comparative application of ISAP markers     

Kerstin Diekmann  Kathrin M. Seibt  Katja Muders  Torsten Wenke  Holger Junghans  Thomas Schmidt  Klaus J. Dehmer 《Genetic Resources and Crop Evolution》2017,64(8):1937-1953

The Genebank at the Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) harbours three different potato collections comprising 2846 wild potato accessions, 2757 accessions of cultivars, landraces and breeding material of Solanum tuberosum L. and 579 Solanum clones originating mainly from South and Central America (as of July 2016). The three collections are maintained via seeds, in vitro culture, cryopreservation or in the field. All four processes are labour and cost intensive. Therefore, methods facilitating the efficient management and maintenance of the collections are needed. We describe the experimental application of the retrotransposon-based Inter-SINE amplified polymorphism (ISAP) marker system for supporting the management of potato collections. Three ISAP primer combinations were evaluated on a set of 259 cultivated and 89 wild potato accessions focussing on three different aspects: diversity analysis, duplicate identification and phylogenetic studies. Compared to up to 29 microsatellites, ISAPs were similarly efficient in monitoring genetic diversity and detecting duplicated accessions. In addition, the three ISAP primer combinations could be applied to wild potato species, although their use in phylogenetic studies is limited due to their highly polymorphic nature. Generally, ISAPs are a very valuable tool in the maintenance of clonally maintained potato collections and for the verification of the identity of accessions.  相似文献   

Connection of growth and wood density with wood anatomy in downy birch grown in two different soil types     

Katri Luostarinen  Katja Hakkarainen  Henri Kaksonen 《Scandinavian Journal of Forest Research》2017,32(8):789-797

Soil affects the anatomy of downy birch wood (Betula pubescens), which raises the question whether the growth of this species differs between mineral and peat soils. The aim of this study was to compare growth, density and structure of xylem of B. pubescens between trees grown in different soils. Both growth and density differed between trees grown in different soils. All measured anatomical characteristics, except double thickness of fibre walls, percentage vessel area and ray number, showed differences between the soil types: the cell dimensions were larger and numbers smaller in trees grown in mineral soil. In peat, high growth rates decreased the wall:lumen ratio of fibres in maturing wood, while no such correlation was observed in trees grown in mineral soil at any studied cambial age. In addition, axial parenchyma may have a different role in trees grown in different soils, as the rapid growth decreased and increased axial parenchyma in mineral and peat soil, respectively. The characteristics affecting wood strength were more similar between trees grown in different soils than those affecting water conductance. The observed differences between trees grown in different soils emphasise rapid growth particularly at young ages and shorter reasonable rotation period in mineral soil.  相似文献   

Influence of thiol metabolism of lactobacilli on egg white proteins in wheat sourdoughs     

Loponen J  König K  Wu J  Gänzle MG 《Journal of agricultural and food chemistry》2008,56(9):3357-3362

In wheat sourdoughs, the degradation of gluten proteins is favored by acidification and reducing conditions. This study aimed to determine the proteolytic degradation of egg white proteins in wheat sourdoughs acidified with lactobacilli differing in their thiol metabolism. Ovotransferrin was the only major egg white protein that degraded during sourdough fermentations. An extensive degradation of ovotransferrin required a heterofermentative lactobacilli starter, Lactobacillus sanfranciscensis, with glutathione reductase activity. Ovotransferrin was more resistant to breakdown when sourdoughs were acidified with homofermentative lactobacilli or a mutant strain of L. sanfranciscensis lacking the glutathione reductase. Its susceptibility to proteolysis in L. sanfranciscensis sourdoughs is thus attributable to thiol accumulation by L. sanfranciscensis, which apparently altered the structure of ovotransferrin through a reduction of disulfide bonds. Proteolytic degradation of ovotransferrin was attributable to wheat aspartic proteinases. In addition to the susceptibility to proteolysis, other functional properties of egg proteins may be influenced by thiol-exchange reactions.  相似文献   

Evaluation of the harmonic scalpel for laparoscopic bilateral ovariectomy in standing horses     

Düsterdieck KF  Pleasant RS  Lanz OI  Saunders G  Howard RD 《Veterinary surgery : VS》2003,32(3):242-250

OBJECTIVE: To evaluate use of the Harmonic Scalpel (Ethicon Endo-Surgery Inc., Cincinnati, OH) for performing laparoscopic bilateral ovariectomy in standing horses. STUDY DESIGN: Experimental study. ANIMALS: Eight mares aged 2-20 years and weighing 410-540 kg. METHODS: Standing laparoscopic bilateral ovariectomy was performed in 8 mares with normal reproductive tract anatomy. The Harmonic Scalpel (an ultrasonically activated instrument) was used to simultaneously transect and obtain hemostasis of the ovarian pedicle. Necropsy was performed on 4 mares 3 days after surgery and 4 mares 30 days after surgery. Gross and histopathologic evaluation of the ovarian pedicles was performed to characterize tissue reaction. RESULTS: Complete hemostasis of the ovarian pedicles was obtained in all mares. Median transection time for the ovarian pedicle was 28 minutes. Postoperative complications included transient fever, moderate subcutaneous emphysema, and incisional seroma formation. On necropsy examination, there were no signs of generalized peritonitis, postoperative hemorrhage, or adhesion formation. Mild to moderate acute inflammation and scar formation with moderate chronic inflammation at the ovarian pedicle was found at 3 and 30 days. Median depth of coagulation necrosis at 3 days was 2.87 mm. CONCLUSIONS: The Harmonic Scalpel appears to provide reliable hemostasis of the ovarian pedicle during elective laparoscopic ovariectomy in horses. Clinical Relevance-The Harmonic Scalpel represents a safe alternative to other methods of hemostasis during elective laparoscopic ovariectomy in horses.  相似文献   

Genetic background of maternal behaviour and its relation to offspring survival     

Katja Grandinson 《Livestock Production Science》2005,93(1):43-50

Maternal behaviour is becoming increasingly important in animal production. Selection for increased litter size at birth in pigs and sheep puts higher demands on the ability of dams to raise large litters. In pig production, the use of loose housing systems for lactating sows increases the importance of good maternal behaviour. Extensive production systems (e.g., ecological farming and outdoor production), where there is a small degree of supervision of the animals, also leaves a greater responsibility with the mother to care for her young. The environment provided by the dam is important for the survival and growth of the offspring in many species. Several behaviour traits of the mother play a role for the offspring's chances of survival and a good start in life. Examples of such behaviour traits are responsiveness towards signals from the offspring (pigs), aggressive behaviour towards the offspring (pigs and sheep), nursing behaviour (pigs and sheep), and fear behaviour (pigs, sheep, and cattle). Some of these traits are in part genetically controlled, and thus possible to improve by selection. Behaviour traits are, however, often difficult to observe and record on a large scale. By studying behaviour, we can gain further understanding about factors affecting survival of the young, and increase our chances to improve maternal behaviour. Improved maternal behaviour would increase the welfare for both mother and young.  相似文献   

Determination of P₅₀ for feline hemoglobin     

Katja Herrmann  DVM    Steve Haskins  DVM  MS  DACVECC 《Journal of Veterinary Emergency and Critical Care》2005,15(1):26-31

Objective: The objective of this study was to determine the PO₂ at 50% hemoglobin oxygenation (P₅₀) of feline hemoglobin (Hb). Design: Prospective in vitro laboratory study. Setting: Research laboratory. Animals: Blood from 10 healthy cats. Interventions: Individual blood samples were equilibrated with calibrated gases of 95, 21, 8, 5, 4, and 2.5% oxygen for tonometric analysis. Measurements: Partial pressure of oxygen (PO₂), oxygen content, oxyhemoglobin saturation, methemoglobin (MetHb), carboxyhemoglobin (COHb), Hb, packed cell volume, hydrogen ion concentration (pH), and partial pressure of carbon dioxide (PCO₂) were measured in duplicate for each blood sample by tonometry. The P₅₀ was calculated from both PO₂/oxyhemoglobin saturation and PO₂/oxygen content (per gram of Hb) curves. Main results: The P₅₀ from the PO₂/oxyhemoglobin saturation curve was 35.6 mmHg and from the PO₂/oxygen content (per gram of Hb) curve was 36.2 mmHg. Conclusions: The oxyhemoglobin dissociation curve for the cat is shifted to the right, and thus, feline Hb has lower oxygen affinity compared with human and canine Hb.  相似文献