Single yeast cell nanomotions correlate with cellular activity.

Living single yeast cells show a specific cellular motion at the nanometer scale with a magnitude that is proportional to the cellular activity of the cell. We characterized this cellular nanomotion pattern of nonattached single yeast cells using classical optical microscopy. The distribution of the cellular displacements over a short time period is distinct from random motion. The range and shape of such nanomotion displacement distributions change substantially according to the metabolic state of the cell. The analysis of the nanomotion frequency pattern demonstrated that single living yeast cells oscillate at relatively low frequencies of around 2 hertz. The simplicity of the technique should open the way to numerous applications among which antifungal susceptibility tests seem the most straightforward

Session 17 Ecophysiology

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A study of lignin formation at the molecular level by scanning tunneling microscopy.

A scanning tunneling microscope (STM) was used to observe the temporal formation and organization of dehydrogenative polymer (DHP) synthesized from coniferyl alcohol. The images obtained elucidate this structure for the first time. The structure of DHP, as seen from STM images, shows long-range order. It appears that DHP consists of building units or modules assembled into larger assemblies called supermodules. Supermodules are interconnected into the overall lattice-like polymer structure with or without spherical regions. One module consists of about 20 monomers, while the supermodule contains about 500 monomers. Calculated molecular weights for modules and supermodules agree with DHP molecular weight distribution peaks. Samples prepared at two different pH values, 6.4 and 7.6, have the same characteristics. The results presented demonstrate that the process of lignification, even in in vitro conditions, is highly ordered, and as such contribute to our understanding of the structure of lignin, a significant constitutive and functional element of cell walls

Determination of gene point mutations by application of higher order central moments — Preliminary research

Point mutations in conserved gene sequences are used as the trace marker for determination of evolutionary distance among the species. Novel method is based on calculation of nucleotide occurrence probability in fixed size moving window and determination of high order central moments. Description of nucleotide occurrence probability can provide high accuracy point mutation detection, and the insight into local sequence

Chenopodium murale L., a long-day plant as a model for physiological and biochemical research

Chenopodium murale L. genus Chenopodium family Chenopodiaceae is a weedy annual widely distributed in Serbia. This is a long-day plant and an early flowering species. We used culture of intact plants in vitro and antioxidative enzymes detection in order to examine the effect of gibberellic acid (GA3) on two key processes during ontogenesis – germination and flowering. Our results showed a sequential expression of antioxidative enzymes during germination. In dry seeds and during early imbibition catalase (CAT) and superoxide dismutase (SOD) activities showed no changes, while peroxidase (POD) activity was under the level of delectability. During radicule protrusion CAT and SOD activity increased. Early seedling development correlates with decrease in SOD, increase in CAT and appearance of POD activity. GA3 delayed and synchronized germination. C. murale photoperiodic sensitivity for flowering shows age-dependant oscillatory changes. Glucose and GA3 have cumulative stimulatory effect on its flowering in vitro. The exposure of 2 months old vegetative plants to continuous darkness, in the presence of GA3 in culture media, resulted in flowering. Therefore transferring to darkness canceled photoperiodic control in C.murale and flowering occurred under autonomous mechanism. We suggest C.murale as a suitable model for investigation of physiological and biochemical mechanisms of growth and developmental processes

Chenopodium rubrum L. as a model plant for physiological and biochemical investigations of ontogenesis in vitro

Chenopodium rubrum L. , is a suitable model plant for studying ontogenesis in vitro as an early flowering species. Culture of intact plants in vitro and antioxidative enzymes detection were performed. Growth pattern to the end of ontogenesis, flowering and seed development are all determined by the photoperiod seedlings experience during induction and evocation of flowering. Different phases of vegetative and reproductive development are characterized by changes in antioxidative enzymes activities. We showed sequential expression of antioxidative enzymes during seed germination. Prior to radicule protrusion, CAT and SOD showed maximal activity, while POD activity appeared later. The highest catalase (CAT) activity was measured at the time of flowering while peroxidases (PODs) are involved in determination of growth and development in accordance with the environmental clues. The absence of some superoxide dismutase (SOD) isoforms could be the indicator of senescence. Seed ageing affect changes in antioxidative status of seeds, germination, seedling growth and flowering