Structural and functional indicators of bacterioplankton of the south stretch of lake Munozero (Karelia)

In article are presented the results of the state of the pelagic part of the south stretch of Lake Munozero (Karelia) according to microbiological indicators for the growing season of 2018. In the furtherance of this goal, 27 water samples were chosen in May, July and September at different strata. Munozero Lake is one of the unique lakes of Karelia due to its high salinity (100 mg/l), low-nutrient water sand organic substances. The total number, cell size dimensional structure and biomass of bacteria were determination by method of luminescence microscopy, by means of filtration through black nucleopore track membranes, after coloration bacteria by acridine orange. The total number of bacteria varied from 0.66 to 1,85 million cells/ml, and the biomass from 0,13 to 0,66 g/m3. The average cell volume varied in the range 0,18–0,34 μm3. Coccus form of bacteria prevailed in numbers. The doubling time and bacterial production were determined by the method of isolated samples. Bacterial production varied between 0.01 and 0.07 g/(m3•day-1). Specific growth rates (day-1) ranged around 0,05–0,2, giving doubling times of 70–364 h. The average daily production for the growing season was 0,65 g/m3•day-1. The physiological activity of bacteria was greatest at the end of the growing season. During the research period, the abundance of saprophytic bacteria growing on fish peptone agar was in the range of 19–550 CFU/ml. the abundance of oligotrophic bacteria growing on from starvation agar variable 200 to 850 CFU/ml. During the study period Water of the south stretch of the Lake Munozero was estimated as clean – moderately polluted with an intermediate quality class of 2–3. The south stretch of the Munozero is characterized as a mesotrophic water body.

Cell tension and mechanical regulation of cell volume

Animal cells use an unknown mechanism to control their growth and physical size. Here, using the fluorescence exclusion method, we measure cell volume for adherent cells on substrates of varying stiffness. We discover that the cell volume has a complex dependence on substrate stiffness and is positively correlated with the size of the cell adhesion to the substrate. From a mechanical force–balance condition that determines the geometry of the cell surface, we find that the observed cell volume variation can be predicted quantitatively from the distribution of active myosin through the cell cortex. To connect cell mechanical tension with cell size homeostasis, we quantified the nuclear localization of YAP/TAZ, a transcription factor involved in cell growth and proliferation. We find that the level of nuclear YAP/TAZ is positively correlated with the average cell volume. Moreover, the level of nuclear YAP/TAZ is also connected to cell tension, as measured by the amount of phosphorylated myosin. Cells with greater apical tension tend to have higher levels of nuclear YAP/TAZ and a larger cell volume. These results point to a size-sensing mechanism based on mechanical tension: the cell tension increases as the cell grows, and increasing tension feeds back biochemically to growth and proliferation control.

BIOCHEMICAL AND MORPHOMETRIC PARAMETERS OF SOME ORGANS AND TISSUES OF HYBRID TILAPIA (OREOCHROMIS SPP.) FOR GROWING WITH USE OF PREPARATION ES-2

The article studies the effect of addition into the feed of Sapropel extract (ES-2 preparation) on the intensity of lipid peroxidation in the liver and gills of hybrid tilapia ( Oreochromis spp. ), as well as on the morphofunctional state of its liver. Sapropel extract caused a decrease in the content of TBA-reactants in the tissues of tilapia liver by 17% compared to the control group. In gills the bioadditive resulted in the increased content of peroxide products by 24%. The introduction of ES-2 in fish feed resulted in reduction of spontaneous and ascorbate-dependent lipid peroxidation rate in the liver by 18%. In the gills of fish, under the influence of Sapropel, the rate of spontaneous lipid peroxidation increased by 27%, the rate of ascorbate-dependent lipid peroxidation - by 23%. The change in the intensity of peroxide processes under the influence of the fodder additive in fish organs is tissue-specific: antioxidant effect was recorded in the liver, prooxidant effect was observed in the gills. The introduction of the Sapropel extract does not lead to a change in the volume of liver nuclei in the test groups of tilapia, while the average cell volume in the experimental group was 37% lower than in the control group. The decrease in cell volume led to the increase in the nuclear-cytoplasmic ratio by 1.9 times in the experimental group compared to the control group. Hepatocyte cytoplasm volume decrease and nuclear-cytoplasmic ratio increase due to addition of ES-2 preparation into productive feed of hybrid tilapia would indicate a rise of functional activity of liver cells.

Seasonal dynamics of the main primary production characteristics of phytoplankton and its microzooplankton grazing in the surface coastal waters of the Black sea

Seasonal variability of phytoplankton biomass, “pure” primary production and its share consumed micro¬zooplankton, as well as the specific microzooplankton grazing rate of phytoplankton for the surface layer (0-1 m) in coastal waters of the Black Sea was studied. Almost 80% of the total annual primary’ produc¬tion of phytoplankton is created by phytoplankton with the average cell volume .from 150 to 4000 mm3. The main share of annual primary production, eaten by microzooplankton (86%) is also associated with these algae sized groups.

Unlocking the Constraints of Cyanobacterial Productivity: Acclimations Enabling Ultrafast Growth

ABSTRACT Harnessing the metabolic potential of photosynthetic microbes for next-generation biotechnology objectives requires detailed scientific understanding of the physiological constraints and regulatory controls affecting carbon partitioning between biomass, metabolite storage pools, and bioproduct synthesis. We dissected the cellular mechanisms underlying the remarkable physiological robustness of the euryhaline unicellular cyanobacterium Synechococcus sp. strain PCC 7002 ( Synechococcus 7002) and identify key mechanisms that allow cyanobacteria to achieve unprecedented photoautotrophic productivities (~2.5-h doubling time). Ultrafast growth of Synechococcus 7002 was supported by high rates of photosynthetic electron transfer and linked to significantly elevated transcription of precursor biosynthesis and protein translation machinery. Notably, no growth or photosynthesis inhibition signatures were observed under any of the tested experimental conditions. Finally, the ultrafast growth in Synechococcus 7002 was also linked to a 300% expansion of average cell volume. We hypothesize that this cellular adaptation is required at high irradiances to support higher cell division rates and reduce deleterious effects, corresponding to high light, through increased carbon and reductant sequestration. IMPORTANCE Efficient coupling between photosynthesis and productivity is central to the development of biotechnology based on solar energy. Therefore, understanding the factors constraining maximum rates of carbon processing is necessary to identify regulatory mechanisms and devise strategies to overcome productivity constraints. Here, we interrogate the molecular mechanisms that operate at a systems level to allow cyanobacteria to achieve ultrafast growth. This was done by considering growth and photosynthetic kinetics with global transcription patterns. We have delineated putative biological principles that allow unicellular cyanobacteria to achieve ultrahigh growth rates through photophysiological acclimation and effective management of cellular resource under different growth regimes.

Size-Selective Predation on Groundwater Bacteria by Nanoflagellates in an Organic-Contaminated Aquifer

ABSTRACT Time series incubations were conducted to provide estimates for the size selectivities and rates of protistan grazing that may be occurring in a sandy, contaminated aquifer. The experiments involved four size classes of fluorescently labeled groundwater bacteria (FLB) and 2- to 3-μm-long nanoflagellates, primarily Spumella guttula(Ehrenberg) Kent, that were isolated from contaminated aquifer sediments (Cape Cod, Mass.). The greatest uptake and clearance rates (0.77 bacteria · flagellate−1 · h−1 and 1.4 nl · flagellate−1 · h−1, respectively) were observed for 0.8- to 1.5-μm-long FLB (0.21-μm3 average cell volume), which represent the fastest growing bacteria within the pore fluids of the contaminated aquifer sediments. The 19:1 to 67:1 volume ratios of nanoflagellate predators to preferred bacterial prey were in the lower end of the range commonly reported for other aquatic habitats. The grazing data suggest that the aquifer nanoflagellates can consume as much as 12 to 74% of the unattached bacterial community in 1 day and are likely to have a substantive effect upon bacterial degradation of organic groundwater contaminants.

Hyperplasia and hypertrophy of chicken cardiac myocytes during posthatching development

For characterization of the growth pattern of cardiac myocytes during posthatching development, cardiac myocytes were enzymatically isolated from the ventricles of 1-, 15-, 29-, and 42-day-old chickens for measurement of myocyte nucleation, length, width, volume, and number, and for immunolabeling of cytoskeletal proteins. Ventricular myocyte number increased 156% from day 1 to day 42. Average cell volume increased more than 400%, and myocytes lengthened 125%, but cell width only increased 53% during this period. All myocytes were mononucleated at day 1. At day 15, 18% of myocytes became binucleated with < 1% of myocytes containing more than two nuclei. Interestingly, binucleated myocytes were able to divide with two nuclei going through mitosis at the same time. As demonstrated by staining with tubulin and alpha-actinin antibodies, two mitotic spindles and two cleavage furrows were formed in dividing binucleated myocytes. At day 42, binucleated myocytes increased to 44% with 11% of myocytes containing more than two nuclei. Sarcomeric alpha-actinin was partially disassembled in prometaphase and was reorganized into regular Z lines of sarcomeres in telophase. Desmin was disassembled in prophase and was reassembled during late telophase. These results suggest that chicken myocytes undergo hypertrophy and continue to proliferate during posthatching maturation, although it is currently believed that myocytes of all vertebrates withdraw from the cell cycle shortly after birth. We provide direct evidence for the first time of in vivo myocyte division in 6-wk-old chicken hearts.

Morphometric Assessment of Pulmonary Toxicity in the Rodent Lung

An overview of the epithelial and interstitial composition of rat respiratory airways shows complexity and variability. Airway epithelium varies in 1) different airway levels; 2) the types and ultrastructure of cells present; and 3) the abundance, type, and composition of stored secretory product. Unbiased sampling of airways is done using airway microdissection with a specific binary numbering system for airway generation. Vertical sections of selected airways are used to sample epithelium and interstitium. We determine the ratios of the volume of epithelial or interstitial cells to the total epithelial or interstitial volume (Vv). The surface of the epithelial basal lamina to the total epithelial or interstitial volume (Sv) is determined using point and intersection counting with a cycloid grid. Using the selector method on serial plastic sections, we determine the number of epithelial or interstitial cells per volume (Nv) of total epithelium or interstitium. We calculate the number of epithelial or interstitial cells per surface of epithelial basal lamina (Ns) by dividing Nv by Sv where the volumes are the same compartment. We calculate average cell volumes (v̄) for specific epithelial and interstitial cells by dividing the absolute nuclear volume by the ratio of the nucleus to cell volume (Vv). By multiplying the average cell volume (v̄) by the ratio of organellar volume to cell volume (Vv), we calculate the average organellar volume per cell. These unbiased stereological approaches are critical in a quantitative evaluation of toxicological injury of rat tracheobronchial airways.

Developmental stages of fetal-type Leydig cells in prepubertal rats

Fetal Leydig cells were studied in rats during and after the perinatal-neonatal period by comparing changes in morphology, number and volume with changes in testicular steroids and serum luteinizing hormone (LH) concentration. Stereologic examination indicated regression of fetal Leydig cells in testis by showing that their total volume as well as the average cell volume decreased between prenatal day 20 and postnatal day 3. The total number and total volume of cells both increased between postnatal days 3 and 11 but the average cell volume did not change during the same time period. Determination of serum LH showed a close correlation between an increase in LH concentration and increases in total number and volume of cells. The combined number of fetal- and adult-type Leydig cells on day 20 was more than 20 times the number of fetal cells at 3 days of age. Electron microscopic analysis showed that fetal Leydig cells after birth formed conspicuous clusters, which were surrounded by a layer of envelope cells and extracellular material. Occasional dividing fetal Leydig cells and possible precursors of fetal or adult Leydig cells were observed. Mitoses of spindle-shaped pericordal cells were frequent during the neonatal period. During and after the second postnatal week fetal Leydig cells again showed signs of regression, indicated by disintegration of the cell clusters, a decrease in cell size, accumulation of collagen between the cells and a decrease in steroid content per cell.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphological and contractile characteristics of rat cardiac myocytes from maturation to senescence

Morphological and contractile characteristics of individual myocytes isolated from rats of 2, 6–9, and 24–25 mo of age were measured. The average myocyte length measured under high power light microscopy in unattached cells increased from 133 microns at 2 mo to 146 microns at 6–9 mo to 162 microns at 24–25 mo of age. The average slack sarcomere length was 1.85, 1.83, and 1.82 microns at 2, 6–9, and 24–25 mo, respectively. The average cell volume measured via Coulter counter techniques approximately doubled between 2 and 24 mo. During the electrically stimulated twitch in individual unloaded myocytes contracting from slack length the absolute amplitude of cell shortening increased with age, but when expressed relative to cell length or as sarcomere shortening the age effect was obliterated. Neither the maximal velocity of myocyte shortening (cell length/s) nor the calculated maximal sarcomere shortening velocity varied with age. The time course of the twitch increased with aging, due largely to an increase in the time to peak shortening. Thus aging is associated with an increase in cell size due to the addition of sarcomeres. Except for a prolonged time course, the twitch contraction characteristics normalized for cell length and sarcomere number in unloaded ventricular myocytes contracting over a range of sarcomere lengths below the slack length do not change appreciably with age.