Bakterien,Pilze und Algen: ein neuer Typ von Kulturpflanzen

Genetic Resources and Crop Evolution -     

Multivalente Assoziationen in diploiden Pollenmutterzellen der Tomate (Lycopersicon esculentum Mill.) und ihre Bedeutung für das Problem der Chromosomengrundzahl

Zusammenfassung 1. Bei der Tomate (Lycopersicon esculentum) zeigen in den frühen meiotischen Stadien die terminalen Makrochromomeren, die sog. Telomeren, besondere Paarungstendenzen, die eine Persistenz terminal gepaarter Gemini bis in die Metaphase I bedingen. Sie sind zusammen mit der höchstwahrscheinlich ähnlichen unspezifischen Anziehung der Kinetochoren der Anlaß zur Entstehung pseudo-multivalenter Assoziationen in der diploiden Tomate.2. Die in den späteren meiotischen Stadien noch nachzuweisenden Zweiergruppen von Chromosomen werden als Folgeerscheinungen der im Pachytän angelegten Verbindungen gedeutet, die als Matrixverklebung oder chromatische Agglutination wirksam sind.3. Die bei der diploiden Tomate in den einzelnen meiotischen Entwicklungsstadien auftretenden multivalenten Assoziationen können deshalb nicht als Hinweis für das Vorliegen homologer Chromosomen und damit einer niedrigeren Chromosomengrundzahl als n=12 dienen.

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Summary 1. Terminal macro-chromomeres of the tomato chromosomes (Lycopersicon esculentum), so-called telomeres, show special pairing tendencies in the early meiotic phases. These pairing affinities are responsible for the persistence of bivalents being in terminal contact up to metaphase I of meiosis. Terminal affinities of telomeres are together with similar unspecific attractions of kinetochores responsible for the origin of pseudo-multivalents in diploid tomatoes.2. Groups of two chromosomes demonstrable in the later meiotic phases are explained as consequences of pachytene-connections being effective in form of matrix-stickiness or chromatic agglutination.3. Multivalents in the various meiotic phases of diploid tomatoes are for these reasons no proof of the existence of homologous chromosomes and it seems impossible to infer a lower chromosome number than n=12 by their existence.

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1. ( ) (Lycopersicon esculentum) , . (, , , ) .2. , , , , ; .3. , , , , , , n=12.

     

Waldverbreitung und Waldeigentum im deutschen Raumplanungsrecht

Ohne Zusammenfassung     

Distribution and prevalence of T. bryosalmonae in Austria: A first survey of trout from rivers with a shrinking population

The first evidence of proliferative kidney disease (PKD) in an Austrian river (the River Kamp) was documented in 2016, and no information on the PKD infection status of trout in other rivers was available. Since then, brown trout (Salmo trutta fario) and rainbow trout (Oncorhynchus mykiss) have been collected from rivers in Upper and Lower Austria for different diagnostic purposes. In this study, we summarize the recent findings of a first survey concerning the distribution of Tetracapsuloides bryosalmonae, the causative agent of proliferative kidney disease (PKD), from these samples. Between September 2015 and October 2017, a total of 280 brown trout and 39 rainbow trout were collected from 21 rivers in the provinces of Upper and Lower Austria. T. bryosalmonae was detected by PCR of kidney tissue in 17 of 21 sampled rivers and in 138 of 280 brown trout as well as in 11 of 39 rainbow trout. Pathological signs of PKD (e.g., hypertrophy of the kidney) were observed in 33 analysed brown trout and six rainbow trout samples. No correlations between fish infected by T. bryosalmonae and the parameters size and age class, condition factor, geological origin of the streams and distribution within the river course were found, while positively tested fish are significantly increased at sampling sites exceeding water temperatures of 15°C for median periods of 115 days. The prevalence within the affected streams or stream sections is highly variable, and in single rivers, infection rates of up to 90% are confirmed.     

Biotic and abiotic controls on body size during critical life history stages of a pelagic fish,Pacific herring (Clupea pallasii)

Variation in growth and body size during critical life history stages can have important implications for life history schedules and survivorship. For Pacific herring (Clupea pallasii), there is still debate as to whether juvenile body size is governed by density‐dependent or ‐independent processes and few have evaluated whether the relative importance of either process shifts over the course of early ontogeny. We used a unique data set consisting of seasonal measurements of abundance, body size, and spatial distribution within a semi‐enclosed basin of Puget Sound (Washington State, U.S.A.) to measure the relative importance of temperature and cohort abundance on body size at distinct time periods, and evaluated whether density‐dependent habitat shifts might be responsible for density‐dependent growth. Over the 9 years of sampling (2001–2010) midsummer body size was positively related to temperatures experienced during the egg/yolk sac and larval stages and unrelated to cohort abundance. However, fall body size was negatively correlated with abundance and uncorrelated with both midsummer body size and temperature, indicating a shift from density‐independent to density‐dependent control over the course of the growing season. Thus, density‐dependent effects may supplant density‐independent effects exhibited early in herring life history. Our data on spatial distributions of herring and their zooplankton prey indicate that density‐dependent reductions in growth may be explained by density‐dependent habitat shifts that lead to reduce overlap of herring with zooplankton. Evidence of density‐dependent growth in marine fish populations is often attributed to exploitative competition, but our results suggest that these patterns may partly be mediated by density‐dependent distribution expansions in to prey‐poor habitat.     

Immunomodulation of rainbow trout (Oncorhynchus mykiss) fry by bath exposure to a β‐glucan from Euglena gracilis

Early developmental stages of fish mostly depend on innate immune factors for their protection. Augmenting these factors by application of different immunostimulatory substances may be beneficial for rearing and survival of the early life stages of fish. Bath administration of stimulants leads to a uniform exposure of fish independent of feed intake and reduces the individual handling. The present study demonstrates the immunostimulatory effect of β‐glucan (bath exposure) in rainbow trout fry at different dosages and exposure time. Rainbow trout fry (avg. wt. 770 mg; 87 days post hatch) were exposed to three different concentrations of β‐glucan (10, 100 and 1000 μg mL^?1) by bath exposure for 1 and 24 h. Expression of immune related genes from pooled internal organ samples of individual fish were analysed using a real time qPCR assay. Expression of complement factors (C3 and factor B) and acute phase proteins (hepcidin, precerebellin and transferrin) was significantly up‐regulated after 24 h bath stimulation with β‐glucan (100 μg mL^?1). These innate immune factors may play a vital role in clearance of pathogens. The expression of most of genes showed both a dose‐ and time‐dependent response. A medium dose (100 μg mL^?1) induced a significant increase in expression of complement factors and acute phase proteins mainly at 24 h exposure, whereas the highest dose of β‐glucan (1000 μg mL^?1) down‐regulated the expression of most of the studied genes. The result from the present study indicates that β‐glucan bath exposure could be applied for enhancing the innate immune factors even in fry.