Multinuclei Occurred Under Cryopreservation and Enhanced the Pathogenicity of Melampsora larici-populina

Melampsora larici-populina is a macrocyclic rust, and the haploid stage with two nuclei and the diploid of mononuclear sequentially occur annually. During the preservation of dry urediniospores at −80°C, we found that one isolate, ΔTs06, was different from the usual wild-type isolate Ts06 at −20°C because it has mixed polykaryotic urediniospores. However, the other spores, including the 0, I, III, and IV stages of a life cycle, were the same as Ts06. After five generations of successive inoculation and harvest of urediniospores from the compatible host Populus purdomii, the isolate ΔTs06 steadily maintained more than 20% multiple nucleus spores. To test the pathogenesis variation of ΔTs06, an assay of host poplars was applied to evaluate the differences between ΔTs06 and Ts06. After ΔTs06 and Ts06 inoculation, leaves of P. purdomii were used to detect the expression of small secreted proteins (SSPs) and fungal biomasses using quantitative real-time PCR (qRT-PCR) and trypan blue staining. ΔTs06 displayed stronger expression of five SSPs and had a shorter latent period, a higher density of uredinia, and higher DNA mass. A transcriptomic comparison between ΔTs06 and Ts06 revealed that 3,224 were differentially expressed genes (DEGs), 55 of which were related to reactive oxygen species metabolism, the Mitogen-activated protein kinase (MAPK) signaling pathway, and the meiosis pathway. Ten genes in the mitotic and meiotic pathways and another two genes associated with the “response to DNA damage stimulus” all had an upward expression, which were detected by qRT-PCR in ΔTs06 during cryopreservation. Gas chromatography–mass spectrometry (GC-MS) confirmed that the amounts of hexadecanoic acid and octadecadienoic acid were much more in ΔTs06 than in Ts06. In addition, using spectrophotometry, hydrogen peroxide (H2O2) was also present in greater quantities in ΔTs06 compared with those found in Ts06. Increased fatty acids metabolism could prevent damage to urediniospores in super-low temperatures, but oxidant species that involved H2O2 may destroy tube proteins of mitosis and meiosis, which could cause abnormal nuclear division and lead to multinucleation, which has a different genotype. Therefore, the multinuclear isolate is different from the wild-type isolate in terms of phenotype and genotype; this multinucleation phenomenon in urediniospores improves the pathogenesis and environmental fitness of M. larici-populina.

Double Nuclei and “TDGs”: Colliding or Activity of Nucleus Monster?

It is known that among active galaxies (AG) with strong emission lines (UV-galaxies, Sy 1 and Sy2, Markarian and Kazarian galaxies, Radio-galaxies, QSO's host galaxies and so on) there are large per cent of objects with double and multiple nucleus. The common sizes and volumes of these nuclei are on the order of a few hundred parsecs or kilo-parsecs. In fact these are not double galaxies or clusters of galaxies as many of astronomers believe, but just the complicated nucleus of AG. The problem is:what are the nature and the birth of these objects?There are in fact two basic suppositions in the subject: (a) The complicated nuclei are the result of merging or colliding of two or more galaxies, or: (b) They are the results of nuclear activity. The results of detailed spectroscopic observations of a number of ”tidal galaxies”, carried out with the 5m Palomar telescope, 2.6m telescope of Ambartsumian Byurakan astrophysical observatory (multi-pupil spectroscopy with Tiger receiver) and 6m telescope of Special Astrophysical observatory of Russia are presented. It is shown that in many cases the ”tidal dwarf galaxies ”(or actually complicated nucleus) are the result of galactic nuclear activity.

Markarian’s First Survey (FBS) - Some Most Interesting Objects

In this review I try to show the important role of the Byurakan Observatory in the discovery and detailed investigations of ultlaviolet excess (UV) galaxies, which are now the center of attention of many observatories. Most new Seyfert (Sy) galaxies by the end of the 1960s, when no more than ten of this type of galaxy were known, were discovered among UV galaxies. In addition, many unusual and interesting galaxies were also discovered among UV galaxies: double and multiple nucleus galaxies, double nucleus Sy galaxies, galaxies with jets, galaxies consisting only of Superassociations (giant HII regions), Sargent-Searle objects, BL Lacs and QSOs possessing a different type of activity according to Ambartsumian. The material presented here overlaps considerably that of some other talks delivered by the author in IAU Symposia Nos. 121 and 194.

Observations of Multiple Nucleus Galaxies

Disturbed Galaxies with two nuclei display the final state of the interaction process of two galaxies (Kollatschny et al., 1986; Fricke and Kollatschny, 1989). A few of these double nucleus galaxies contain Seyfert nuclei.

Far-Infrared Properties of Markarian Galaxies with Multiple Nuclei

We have coadded the IRAS data on a sample of 188 multiple-nucleus and morphologically peculiar Markarian galaxies noted as “interacting” in the compilation of Mazzarella and Balzano (1986). We have increased the number of objects in this sample with 60μm and 100μm IRAS detections by a factor of two from what is available in the Point Source Catalog, allowing the determination of far-infrared (FIR) luminosities and colors for over 130 morphologically peculiar Markarian galaxies. The galaxies in this sample have diameters less than 2′, and thus were seen as point sources by IRAS. All far-infrared properties discussed here apply to the entire multiple-nucleus or peculiar system. These data provide a unique opportunity to study the far-infrared properties of mergers which have prior indications of starburst or Seyfert activity as evidenced by their ultraviolet excess.

Multi - Frequency Observations of Multiple Nucleus Markarian Galaxies

Multiple nucleus Markarian Galaxies may owe their origin to merging processes among galaxies. They may therefore be key objects for our understanding of galaxy evolution and the origin of nuclear activity. From morphological and multi-spectral data we show that these objects are in an unusually high state of dynamical and nuclear activity (starbursts, Seyfert activity) as would be expected from advanced stages of galaxy mergers.