An unusual sexual stage in the alkalophilic ascomycete Sodiomyces alkalinus

Exploring life cycles of fungi is insightful for understanding their basic biology and can highlight their ecology. Here, we dissected the sexual and asexual life cycles of the obligate alkalophilic ascomycete Sodiomyces alkalinus that thrives at extremely high pH of soda lakes. S. alkalinus develops acremonium-type asexual sporulation, commonly found in ascomycetous fungi. However, the sexual stage was unusual, featuring very early lysis of asci which release young ascospores inside a fruit body long before its maturation. In a young fruit body, a slimy matrix which originates from the combined epiplasm of asci and united cytoplasm of the pseudoparenchymal cells, surrounds pooled maturing ascospores. Upon maturity, the ascospores are forcibly released through a crack in the fruit body, presumably due to an increased turgor pressure. These features of the sexual stage development resemble the ones found in unrelated marine fungi, indicating convergent evolution of the trait. We hypothesise these developmental features of S. alkalinus to be adaptive in the conditions of periodically inundated rims of soda lakes where the fungus thrives.     

Lipids and soluble carbohydrates in the mycelium and ascomata of alkaliphilic fungus Sodiomyces alkalinus

Extremophiles - Alkaliphilic fungi are fundamentally different from alkalitolerant ones in terms of mechanisms of adaptation. They accumulate trehalose in cytosol and phosphatidic acids...     

Regional difference in endothelium-dependent vascular responses upon the flow rate elevation

In anaesthetised rabbits, femoral artery manifested a maximal reserve capacity in its vasodilatory response to the flow speed acceleration. In order of the capacity diminishing, this artery is followed by renal artery, abdominal aorta, celiacus tube, common carotid artery. The endothelium-dependent flow-induced response is important for restricting the flow's linear speed.     

Antigenic activity of oral whole-culture meningococcal serogroup B vaccine

The whole-culture vaccine preparation of Neisseria meningitidis, serogroup B, obtained by cultivation in a computer-controlled bioreactor, was studied. The preparation was shown to contain antigenically active polysaccharide, outer membrane proteins, as well as lipooligosaccharide, faintly pyrogenic and with low toxicity. After oral immunization of rabbits a multiple increase in the levels of IgG antibodies to these antigens in their blood serum was noted during the period of observation (303 days).     

Ultrastructure of resting cells of some non-spore-forming bacteria

Using electron microscopy (ultrathin sections and freeze-fractures), we investigated the ultrastructure of the resting cells formed in the cultures of Micrococcus luteus, Arthrobacter globiformis, and Pseudomonas aurantiaca under conditions of prolonged incubation (up to 9 months). These resting cells included cyst-like forms that were characterized by complex cell structure and the following ultrastructural properties: (i) a thickened or multiprofiled cell wall (CW), typically made up of a layer of the preexisting CW and one to three de novo synthesized murein layers; (ii) a thick, structurally differentiated capsule; (iii) presence of large intramembrane particles (d = 180-270 A), occurring both on the PF and EF sides of the membrane fractures of M. luteus and A. globiformis; (iv) a peculiar structure of the cytoplasm, which was either fine-grained or lumpy (coarse-grained) in different parts of the cell population; and (v) a condensed nucleoid. Intense formation of cyst-like cells occurred in aged (2- to 9-month-old) bacterial cultures grown on diluted complex media or on nitrogen-, carbon-, and phosphorus-limited synthetic media, as well as in suspensions of cells incubated in media with sodium silicate. The general morphological properties, ultrastructural organization, and physiological features of cyst-like cells formed during the developmental cycle suggest that constitutive dormancy is characteristic of non-spore-forming bacteria.     

Analysis of the Ca2+ response of mycelial fungi to external effects by the recombinant aequorin method

Using the mutant strain Aspergillus awamori 66A producing a recombinant Ca2+-dependent photosensitive protein aequorin, the dynamics of Ca2+ was studied for the first time in the cytosol of the micromycetes exposed to stressful factors, such as an increase in extracellular Ca2+ to 50 mM, hypoosmotic shock, and mechanical shock. Cell response to stress proved to involve an increase in the Ca2+ concentration in the cytosol, which was determined from the amplitude of aequorin luminescence and the time of the amplitude enhancement and relaxation. The level of Ca2+ response depended on the physiological stimulus. Inhibitory analysis with various agents that block Ca2+ channels and with agonists that specifically enhance the activity of the channels suggested that (1) the level of Ca2+ in the cytosol of micromycetes increases in response to stress because of the ion influx from both the growth medium and intracellular reservoirs and (2) the potential-dependent transport systems play the major role in the Ca2+ influx into the cytosol of the micromycete cells.     

Effect of polylysine on transformations and permeability of negative vesicular membranes

Small (40-60 nm in diameter) and large (300-350 nm) negative vesicles were complexed with a cationic polypeptide, poly-L-lysine (PL). Laser microelectrophoresis experiments showed that in small vesicles rendered anionic with the addition of cardiolipin (CL(2-)), only the CL(2-) in the outer leaflet is involved in the complexation with PL. Calorimetric and other data demonstrate that the binding of PL to the membrane surface causes domains ("rafts") of CL(2-) to form in the outer leaflet, and it is these domains that electrostatically bind the polymer. The kinetics of transmembrane permeation of doxorubicin (Dox, a fluorescent anti-tumor drug) was monitored with and without PL binding to the outer surface of the vesicles. It was found that PL mediates the permeation of Dox into the vesicle interior. In the absence of PL, the Dox molecule (possessing an amino group of pK(a)=8.6) binds to the anionic vesicles in the protonated form and, consequently, suffers an impaired mobility through the membrane. On the other hand, when the PL covers the vesicle surface, Dox passes though the membrane with greater ease. The effects of salt and polyanion on the stability of PL-vesicle complexes and the PL-mediated Dox permeation are also discussed.     

Effect of Bacillus subtilis on the rumen microbial community and its components exhibiting high correlation coefficients with the host nutrition, growth, and development

T-RFLP investigation of the microbial community of the ruminal fluid of calves revealed changes in the microbiocenosis resulting from feeding the animals with biofilm-protected Bacillus subtilis cells. In the control animals, which switched from the diary to the vegetable diet, the phylum Firmicutes predominated Firmicutes (55.11 ± 1.97%), in particular the class Clostridia (53.10 ± 2.06%), families Lachnospiraceae (25.93 ± 1.41%) and Clostridiaceae (9.90 ± 1.35%). Members of the phyla Bacteroidetes (11.15 ± 2.88%) and Actinobacteria (9.27 ± 1.95%) were also present. Uncultured forms constituted 17.28 ± 2.01%. The share of bacilli (family Bacillaceae) was below 2% (1.46 ± 0.41%). Introduction of B. subtilis cells into the rumen of experimental animals increased the share of Bacillaceae to 2.80 ± 0.30%. The numbers of Thermoanaerobacteriaceae, Peptostreptococcaceae, and Alicyclobacillaceae increased by an order of magnitude. The numbers of Pseudomonadaceae, Burkholderiaceae, and uncultured Bacteroidetes increased twofold. Increased numbers of the rumen bacteria and protozoa, elevated fatty acid content, and higher ammonia emission indicated increased efficiency of digestion. Some families, including the domineering ones, included the members with different directions of the correlation with the indices of rumen digestion. The introduced bacilli stimulated the phylotypes with the positive correlation coefficients and suppressed those with the negative correlation. This, the rumen ecosystem was modified in the direction of improved digestion. The functional role of the members of the microbial community, for which the correlations were negative, weakly associated, or unassociated with the indices of rumen digestion are discussed.