Diatom derived polyunsaturated aldehydes do not structure the planktonic microbial community in a mesocosm study     

Paul C  Reunamo A  Lindehoff E  Bergkvist J  Mausz MA  Larsson H  Richter H  Wängberg SÅ  Leskinen P  Båmstedt U  Pohnert G 《Marine drugs》2012,10(4):775-792

Several marine and freshwater diatoms produce polyunsaturated aldehydes (PUA) in wound-activated processes. These metabolites are also released by intact diatom cells during algal blooms. Due to their activity in laboratory experiments, PUA are considered as potential mediators of diatom-bacteria interactions. Here, we tested the hypothesis that PUA mediate such processes in a close-to-field mesocosm experiment. Natural plankton communities enriched with Skeletonema marinoi strains that differ in their PUA production, a plankton control, and a plankton control supplemented with PUA at natural and elevated concentrations were observed. We monitored bacterial and viral abundance as well as bacterial community composition and did not observe any influence of PUA on these parameters even at elevated concentrations. We rather detected an alternation of the bacterial diversity over time and differences between the two S. marinoi strains, indicating unique dynamic bacterial communities in these algal blooms. These results suggest that factors other than PUA are of significance for interactions between diatoms and bacteria.  相似文献   

Phenolic profiles of two Melampyrum species differing in susceptibility to Cronartium rust     

Juha Kaitera  Johanna Witzell 《European journal of plant pathology / European Foundation for Plant Pathology》2016,144(1):133-140

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Antagonistic activity of fungal endophyte filtrates against Gremmeniella abietina infections on Aleppo pine seedlings     

Carmen Romeralo  Johanna Witzell  Rosa Romeralo-Tapia  Leticia Botella  Julio Javier Diez 《European journal of plant pathology / European Foundation for Plant Pathology》2015,143(4):691-704

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Cytotoxic Effects of Serum from Equine Grass Sickness Cases on Neuro-2a and PC12 Tet-Off Cell Lines: Implication for Using In Vitro Methods as Antemortem Diagnostic Tools     

Hassan Malekinejad  Sara Bull  Fatemeh Rahmani  Johanna Fink-Gremmels 《Journal of Equine Veterinary Science》2012,32(1):53-59

A wide variety of clinical and paraclinical methods have been used for diagnosis of equine grass sickness (EGS), but none of them could absolutely confirm the diagnosis, and postmortem pathologic examination is still considered the final step in precise diagnosis of EGS. Use of in vitro cell toxicity caused by EGS serum on neuronal cell lines was investigated. Three well-known cytotoxic methods were used to investigate the cytotoxicity of EGS serum on neuro-2a and genetically engineered PC12 Tet-Off P53 cells. The results of alamar blue reduction as an index for mitochondrial activities and intracellular adenosine triphosphate content assays, but not neutral red uptake, indicate that the EGS serum may affect the mitochondrial function and cellular metabolism at up to 60% of the cases. The results of present study might be used for diagnosis of EGS cases. Further studies with high sample size may lead us to uncover the pathogenesis of EGS and to increase the sensitivity and applicability of in vitro techniques as diagnostic tools.  相似文献   

Development of a live, attenuated, potential vaccine strain of R. equi expressing vapA and the virR operon, and virulence assessment in the mouse     

Whitehead AE  Parreira VR  Hewson J  Watson JL  Prescott JF 《Veterinary immunology and immunopathology》2012,145(1-2):479-484

Pneumonia caused by Rhodococcus equi remains a significant problem in foals. The objective of this study was to develop a safe and efficacious attenuated strain of R. equi for eventual use in oral immunization of foals. The approach involved expression of vapA in a live, virulence plasmid-negative, strain of R. equi (strain 103-). PCR-amplified fragments of the vapA gene, with and without the upstream genes virR, orf5, vapH, orf7 and orf8 (orf4-8), were cloned into a shuttle vector pNBV1. These plasmids, named pAW48A and pAWVapA respectively, were electroporated into strain 103-. The presence of the recombinant vectors in the attenuated strain (103-) and the integrity of the inserted genes were confirmed, and both constructs expressed VapA. The virulence of the two strains was compared to that of wild type R. equi 103+ and negative controls by their intravenous inoculation into mice, followed by examination of liver clearance 4 days later. Mice inoculated with R. equi 103-, 103-/pAWVapA and 103-/pNBV1 completely cleared infection, whereas strain 103-/pAW48A persisted in 47% of mice.  相似文献   

What is your diagnosis? Equine ovarian cyst fluid     

Rigas JD  Montilla HJ  Tornquist SJ  Valentine BA  Kutzler MA 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2012,41(3):435-436

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Prediction of nutritive values,morphology and agronomic characteristics in forage maize using two applications of NIRS spectrometry     

Mårten Hetta  Zohaib Mussadiq  Johanna Wallsten  Magnus Halling  Christian Swensson  Paul Geladi 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2017,67(4):326-333

This study evaluates nutritive, morphological and agronomic characteristics of forage maize predicted by using a high-quality near-infrared (NIR) spectrometer and an NIR hyperspectral-imaging technique using partial least squares (PLS) regression models. The study includes 132 samples of dried milled whole-plant homogenates of forage maize with variation in maturity, representing two growing seasons, three locations in Sweden and three commercial maize hybrids. The samples were measured by a classical sample cup NIR spectrometer and by a pushbroom hyperspectral-imaging instrument. The spectra and a number of variables (crude protein, CP, neutral detergent fibre, starch, water soluble carbohydrates (WSC) and organic matter digestibility), morphological variables (leaves, stems & ears) and crop yield were used to make PLS calibration models. Using PLS modelling allowed the determination of how well maize variables can be predicted from NIR spectra and a comparison of the two types of instruments. Most examined variables could be determined equally well, by both instruments, but the pushbroom technique gave slightly better predictions and had higher analytical capacity. Predictions of CP, starch, WSC and the proportions of ears in the maize gave robust. The findings open new possibilities to further utilise the technology in plant breeding, crop management, modelling and forage evaluation.  相似文献   

New insights into the evolution,hormonal regulation,and spatiotemporal expression profiles of genes involved in the Gfra1/Gdnf and Kit/Kitlg regulatory pathways in rainbow trout testis     

Ahmed Maouche  Edouard Curran  Anne-Sophie Goupil  Elisabeth Sambroni  Johanna Bellaiche  Florence Le Gac  Jean-Jacques Lareyre 《Fish physiology and biochemistry》2018,44(6):1599-1616

The present study aimed to investigate whether the Gfra1/Gdnf and/or Kit/Kitlg regulatory pathways could be involved in the regulation of spermatogonial cell proliferation and/or differentiation in fish. Homologs of the mammalian gfra1, gdnf, kitr, and kitlg genes were identified in gnathostomes and reliable orthologous relationships were established using phylogenetic reconstructions and analyses of syntenic chromosomal fragments. Gene duplications and losses occurred specifically in teleost fish and members of the Salmoninae family including rainbow trout (Oncorhynchus mykiss) and Atlantic salmon (Salmo salar). Some duplicated genes exhibited distinct spatiotemporal expression profiles and were differently regulated by hormones in rainbow trout. Undifferentiated type A spermatogonia expressed higher levels of kitrb and kitra2 making them possible target cells for the gonadal kitlgb and somatic kitlga before the onset of spermatogenesis. Interestingly, gdnfa and gdnfb ohnologous genes were poorly expressed before the onset of spermatogenesis. The expression level of gdnfb was correlated with that of the vasa gene suggesting that the late increased abundance of gdnfb during spermatogenesis onset was due to the increased number of spermatogonial cells. gfra1a2 was expressed in undifferentiated type A spermatogonia whereas gfra1a1 was mainly detected in somatic cells. These observations indicate that the germinal gdnfb ligand could exert autocrine and paracrine functions on spermatogonia and on testicular somatic cells, respectively. Fsh and androgens inhibited gfra1a2 and gdnfb whereas gfra1a1 was stimulated by Fsh, androgens, and 17α, 20β progesterone. Finally, our data provide evidences that the molecular identity of the male germ stem cells changes during ontogenesis prior to spermatogenesis onset.  相似文献   

Comparing buffer zone alternatives in forest planning using a decision support system     

Johanna Lundström  Karin Öhman  Hjalmar Laudon 《Scandinavian Journal of Forest Research》2018,33(5):493-501

Increased awareness of the connection between forest management activities and negative effects on water quality means that forestry needs to consider its potential impact on the aquatic environment when planning operations. Protective buffer zones are effective, but their design can vary. To be able to incorporate up-to-date scientific theory into practical applications easy-to-use planning tools are needed. In this study, we evaluate different buffer zone alternatives by using the freely available decision support system Heureka. The consequences on both economic and ecological values over a time period of 100 years were evaluated for two buffer zone approaches and three management alternatives within the buffer zones. Results indicated that there is a trade-off between economic and ecological values when managing the buffer zones. To be able to perform the analyses within Heureka, a new tool was developed. This software development provides access to a forest planning tool that can help improve nature conservation.  相似文献   

Glucose and ammonium additions affect needle decomposition and carbon allocation by the litter degrading fungus Mycena epipterygia     

Johanna Boberg  Roger D. Finlay  Jan Stenlid  Torgny Näsholm  Björn D. Lindahl 《Soil biology & biochemistry》2008,40(4):995-999

Saprotrophic microorganisms in soils have traditionally been assumed to be carbon (C) limited, since additions of readily assimilable carbohydrates usually result in increased respiration. In many forest soils, however, rapid nitrogen (N) immobilization and increased microbial growth in response to N addition indicate N limitation. Here we test whether this apparent contradiction could be explained by changes in C allocation between microbial growth and respiration (i.e. changed C-use efficiency) under controlled conditions in laboratory microcosms. Respiration, mycelial production and needle mass loss were monitored after application of glucose or ammonium sulphate to Pinus sylvestris needles inoculated with the litter decomposer fungus Mycena epipterygia. Addition of ammonium resulted in a 32% increase in respiration, 31% increase in needle mass loss and increased mycelial production, indicating that both growth and activity of the fungus were N limited. In spite of N limitation, additions of glucose resulted in a 19% increase in respiration but had no effect on mycelial production and led to a 17% decrease in needle mass loss, indicating a reduced C-use efficiency of the fungus. The capacity of individual fungi to adapt their C-use efficiency to C availability implies that additions of labile C could increase respiration even under N-limited conditions.  相似文献