Short-term effects of prescribed burning on wood-rotting fungi

Summary

Insecticidal, repellent, antimicrobial activity and phytotoxicity of essential oils: With special reference to limonene and its suitability for control of insect pests : Review

Selostus: Monoterpeenit kasvinsuojelussa: erityisesti limoneenin vaikutus eri eliöryhmiin

Nasopharyngeal colonization by pathogenic bacteria: effect of polymorphisms in innate immune genes of young children

Nasopharyngeal bacteria can asymptomatically colonize the nasopharynx of infants and young children but are also associated with the development of respiratory infections and diseases. Such nasopharyngeal bacteria include Streptococcus pneumoniae, Moraxella catarrhalis, Haemophilus influenzae and Staphylococcus aureus. The host defense against invading pathogens is largely relies germline-encoded pattern recognition receptors (PRR), which are expressed on the cells of innate immunity, and different cytokines. These include toll-like receptors (TLR), mannose-binding lectin (MBL) and different cytokines such as IL-17A. Single nucleotide polymorphisms (SNP) in these receptors and cytokines have been reported. The aim of this study was to investigate genetic polymorphisms in the genes for TLR2, 3 and 4, MBL as well as for IL-17A and their associations with nasopharyngeal pathogenic bacterial colonization during a two-year follow-up. The study revealed that polymorphisms in TLRs, MBL2 and IL17A are associated with the nasopharyngeal bacterial colonization in young children. Healthy young (2.6 months of age) children with variant types of MBL2, TLR2 R753Q or TLR4 D299G had an increased risk to be colonized by S. pneumonia, S. aureus or M. catarrhalis, respectively. Moreover, variant types of MBL2 in healthy children with might facilitate human rhinovirus (HRV)-induced S. pneumoniae colonization at 2.6 months of age. The polymorphism of TLR4 D299G was shown to be associated with M. catarrhalis colonization throughout the whole two-year follow-up (2.6, 13 and 24 months of age) and also with the bacterial load of this pathogen. Also, the polymorphism of IL17A G152A was shown to be associated with increased risk to be colonized by S. pneumoniae at 13 and 24 months of age. Furthermore, the results suggest that IL17A G152A has an effect on production of serum IL-17A already at young age. In conclusion, the results of this study indicate that polymorphisms in the key PRRs and IL17A seem to play an important role to colonization of S. pneumoniae, M. catarrhalis, and S. aureus in healthy young Finnish children. The nasopharyngeal colonization by these pathogenic bacteria may further promote the development of respiratory infections and may be related to development of asthma and allergy in the later life of children. These findings offer a possible explanation why some children have more respiratory infections than other children and provide a rational basis for future studies in this field.

Food webs in the era of molecular revolution – Like resolving the Gordian knot with a tricorder

Living nature consists of countless organisms, which are classified into millions of species. These species interact in many ways; for example predators when foraging on their prey, insect larvae consuming plants, and pathogenic bacteria drifting into humans. In addition, abiotic nature has a great initiative impact on life through many factors (including sunlight, ambient temperature, and water. In my thesis, I have studied interactions among different life forms in multifaceted ways. The webs of these interactions are commonly referred to as food webs, describing feeding relationships between species or energy transfer from one trophic level to another. These ecological interactions – whether they occur between species, between individuals, or between microorganisms within an individual – are among the greatest forces affecting natural communities. Relationships are tightly related to biological diversity, that is, species richness and abundances. A species is called a node in food web vocabulary, and its interactions to other species are called links. Generally, Artic food webs are considered to be loosely linked, simple structures. This conception roots into early modern food webs, where insects and other arthropods, for example, were clumped under one node. However, it has been shown that arthropods form the greatest part of diversity and biomass both in the tropics and in Arctic areas. Earlier challenges of revealing the role of insects and microorganisms in interactions webs have become possible with the help of recent advances in molecular techniques. In the first chapter, I studied the prey diversity of a common bat, Myotis daubentonii, in southwestern Finland. My results proved M. daubentonii being a versatile predator whose diet mainly consists of aquatic insects, such as chironomid midges. In the second chapter, I expanded the view to changes in seasonal and individual-based variation in the diet of M. daubentonii including the relationship between available and observed prey. I found out that chironomids remain the major prey group even though their abundance decreases in proportion to other insect groups. Diet varied a lot between individuals, although the differences were not statistically significant. The third chapter took the study to a large network in Greenland. I showed that Artic food webs are very complex when arthropods are taken into account. In the fourth chapter, I examined the bacterial flora of M. daubentonii and surveyed the zoonotic potential of these bacteria. I found Bartonella bacteria, of which one was described as a new species named after the locality of discovery. I have shown in my thesis that Myotis daubentonii as a predator links many insect species as well as terrestrial and aquatic environments. Moreover, I have exposed that Arctic food webs are complex structures comprising of many densely linked species. Finally, I demonstrated that the bacterial flora of bats includes several previously unknown species, some of which could possibly turn in to zoonosis. To summarize, molecular methods have untied several knots in biological research. I hope that this kind of increasing knowledge of the surrounding nature makes us further value all the life forms on earth.