Labelling of lupine nodule metabolites with 14CO2 assimilated from the leaves

On feeding ¹⁴CO₂ to the shoots of lupine (25 mCi per plant) 30 min was the minimal time needed to determine the incorporation of label into bacteroid compounds. The predominant incorporation, exhibited in all root, nodule and bacteroid samples after 30 min exposure, was into sucrose (45–90% of the corresponding fraction radioactivity) of the neutral fraction; into malate (30–40%) of the acid fraction; into aspartic acid and asparagine (60–80% in sum) of the basic fraction. The composition of carbon compounds containing the greatest amount of ¹⁴C in the cytosol of nodules and in bacteroids was similar. Their radioactivity after 30 min exposure was for bacteroids (nCi per g of bacteroid fr. wt): sucrose 5.73, glucose 1.00, malate 0.15, succinate 0.11; for the nodule cytosol (nCi per g of nodule fr. wt): sucrose 200.00, glucose 8.40, malate 9.34, succinate 8.50. Thus it was demonstrated that in lupine, sucrose is the main photoassimilate entering not only into nodules but also into bacteroids. The biosynthesis of aspartic acid and asparagine occurs during nitrogen fixation in bacteroids.     

Developing criteria for evaluation of geroprotectors as a key stage toward translation to the clinic

In the coming decades, a massive shift in the aging segment of the population will have major social and economic consequences around the world. One way to offset this increase is to expedite the development of geroprotectors, substances that slow aging, repair age‐associated damage and extend healthy lifespan, or healthspan. While over 200 geroprotectors are now reported in model organisms and some are in human use for specific disease indications, the path toward determining whether they affect aging in humans remains obscure. Translation to the clinic is hampered by multiple issues including absence of a common set of criteria to define, select, and classify these substances, given the complexity of the aging process and their enormous diversity in mechanism of action. Translational research efforts would benefit from the formation of a scientific consensus on the following: the definition of ‘geroprotector’, the selection criteria for geroprotectors, a comprehensive classification system, and an analytical model. Here, we review current approaches to selection and put forth our own suggested selection criteria. Standardizing selection of geroprotectors will streamline discovery and analysis of new candidates, saving time and cost involved in translation to clinic.     

Detection of mutation in transgenic CHO cells using green fluorescent protein as a reporter

A novel approach was developed for rapidly estimating the frequency of specific mutations in genetically engineered Chinese hamster ovary (CHO) cells. We designed double-transgenic CHO cell lines that contain a transgene consisting of the sequence coding for green fluorescent protein under the control of a tetracycline (Tet) responsive promoter and a second transgene coding for the constitutively expressed Tet repressor. Cultures of these CHO cells were treated with gamma-radiation, N-methyl-N-nitrosourea or methyl methanesulfonate, and the fluorescence of individual cells from both control and treated cultures was measured by flow cytometry. The treatments increased the number of highly fluorescent cells, those with presumed mutations in the Tet-repressor gene. Mutant cells from gamma-radiation-exposed cultures were isolated by fluorescence-activated cell sorting, cultured, and individual clones expanded. A PCR-based analysis indicated that the highly fluorescent expanded cells had lost the transgene coding for the Tet repressor, suggesting that the system mainly detects large genetic alterations. A similar approach may be useful for making high-throughput in vivo models for mutation detection.     

A New Freshwater Naked Lobose Amoeba Korotnevella venosa n. sp. (Amoebozoa,Discosea)

A new freshwater species of naked lobose amoebae Korotnevella venosa n. sp. isolated from freshwater pond in St. Petersburg, Russia was studied with light and transmission electron microscopy. Basket scales of this species have six vertical columns supporting perforated rim. The latter has tongue‐like broadening with membranous region. Vertical columns bifurcate at both ends so that neighboring columns are connected by their bifurcations forming combined structure. Basket scales of K. venosa are similar to those of Korotnevella hemistylolepis in having six full‐length vertical columns and perforated rim. At the same time, they are different in having tongue‐like broadening of perforated rim with membranous region and absence of six half‐length columns and an intermediate crosspiece. Phylogenetic trees based on 18S rDNA gene placed K. venosa either at the base of the whole Korotnevella clade, next to K. hemistylolepis, or as a sister to the clade comprising Korotnevella species with latticework basket in large scales.     

Pinjata ruminata gen. et sp. n.—A New Member of Centrohelid Family Yogsothothidae (Haptista: Centroplasthelida) from the Brackish River

A new genus and species of centrohelid heliozoan Pinjata ruminata from the Tuzlukkol’ River (Orenburg Region of Russia) and Gor?koe Lake (Chelyabinsk Region of Russia) is studied with light‐ and electron microscopy. Pinjata ruminata has two types of plate scales, partially running up the sides of the axopodia. Inner plate scales (3.2–4.9 × 1.5–2.6 μm) are flat, ovate‐oblong and have a broad axial thickening and a thin electron‐dense border. Outer plate scales (4.2–6.7 × 1.5–3.0 μm) are concave, elongated, of irregular shape, often curved, and broadened towards one end. Roundish depressions are forming two rows on both sides of the narrow axial thickening. The cells are attached to the substratum. Molecular phylogenetic analysis based on the SSU rDNA robustly placed P. ruminata in the family Yogsothothidae. This position is confirmed with the presence of five panacanthocystid increase regions. The morphology of the new genus is in a good accordance with diagnosis of the family. The status of a genus “Heteroraphidiophrys” is discussed. Other potential findings of Pinjata from literature are analyzed. Pinjata represents the third lineage of centrohelids, characterized with the presence of only tangentially oriented plate scales. The halophilic nature of Yogsothothidae is suggested.     

Red fox takeover of arctic fox breeding den: an observation from Yamal Peninsula, Russia

Here, we report from the first direct observation of a red fox (Vulpes vulpes) intrusion on an arctic fox (Vulpes lagopus) breeding den from the southern Arctic tundra of Yamal Peninsula, Russia in 2007. At the same time, as a current range retraction of the original inhabitant of the circumpolar tundra zone the arctic fox is going on, the red fox is expanding their range from the south into arctic habitats. Thus, within large parts of the northern tundra areas the two species are sympatric which gives opportunities for direct interactions including interference competition. However, direct first-hand observations of such interactions are rare, especially in the Russian Arctic. In the present study, we observed one red fox taking over an arctic fox breeding den which resulted in den abandonment by the arctic fox. On July 19, eight arctic fox pups were observed on the den before the red fox was observed on the same den July 22. The pups were never seen at the den or elsewhere after the red fox was observed on the den for as long as we stayed in the area (until August 10). Our observation supports the view that direct interference with red fox on breeding dens may contribute to the range retraction of arctic foxes from the southern limits of the Arctic tundra in Russia.     

The structural peculiarities of condensed DNA micro- and nanoparticles formed in PCR

Studies of DNA condensation have opened new perspectives in biotechnology and medicine. DNA condensation induced by polyamines or trivalent metal ions in vitro at room temperature has been investigated in detail. Our recent studies have demonstrated Mg²⁺-mediated formation of DNA condensates during the PCR. In this study, we report the unique morphology and fine structure of PCR-generated condensed DNA particles using electron and atomic force microscopy. The principal morphologies of studied DNA condensates are 3D particles of micrometer dimensions, oval microdisks of nanometer thickness, filaments, and compact nano-sized particles. SEM examinations have revealed a new structural type of spherical and elliptical 3D microparticles formed by numerous definitely oriented microdisks and their segments. AFM revealed a granular structure of the microdisk surface and the smallest nano-sized disks and thinnest nanofibrils – that appear to be the primary products of DNA condensation during the PCR. We suggest that the formation of DNA nanofibrils and nanodisks in PCR occurs due to Mg²⁺ – mediated intermolecular (lateral) and intramolecular condensation of ssDNA. Aggregation of elementary nanodisks in the course of thermal PCR cycles, occurring both by magnesium cations and via complementary interactions, give a rise to large nano-sized aggregates and more complex microparticles.     

Antiangiogenic and antivascular effects of a recombinant tumstatin-derived peptide in a corneal neovascularization model

Tumstatin, a cleavage fragment of collagen IV, is a potent endogenous inhibitor of angiogenesis. Tumstatin-derived peptide T8 possesses all angiostatic properties of full-length tumstatin and indirectly suppresses tumor growth. The potential of T8 to block pathological angiogenesis in the eye has not been explored yet. Here we assess antiangiogenic effects of a recombinant T8 peptide in rabbit corneal neovascularization models. The fusion protein consisting of T8 and thioredoxin was synthesized in a highly efficient Escherichia coli expression system, isolated using ion-exchange chromatography and cleaved with TEV (tobacco etch virus) protease. The target peptide was purified on an anion-exchange resin and by reversed phase high-performance liquid chromatography. The recombinant peptide suppressed the proliferation of basic fibroblast growth factor-induced SVEC-4-10 endothelial cells (simian virus 40-immortalized murine endothelial cells) and inhibited tube formation in these cells in a dose-dependent manner. In rabbit corneal neovascularization models T8 demonstrated the ability to prevent pathological angiogenesis (when injected simultaneously with the induction of neovascularization) and, moreover, to promote the regression of newly-formed blood vessels (when injected on day 8 after angiogenesis stimulation). Our results suggest that T8 may have a therapeutic potential in the treatment of ocular neovascular diseases.