Seasonal changes in anatomical and morphological structure and the content of phytohormones and sugars in underground shoots of a long-rhizome perennial grass <Emphasis Type="Italic">Phalaroides arundinacea</Emphasis>

Seasonal changes in the anatomical and morphological structure and metabolic activity of rhizomes were studied in a perennial grass reed canary-grass (Phalaroides arundinacea (L.) Rauschert). An active formation of the underground stock of meristems and a rhizome weight accumulation were shown in the later half of a growth period, after a decline in the growth of aboveground shoots. A reduction in the cross-section area and the relative contribution of the central cylinder together with of an increase in the volume of a cortex parenchyma were found in the rhizomes at the end of the growth period. In autumn, the rhizomes were characterized by the high content of cytokinins and oligosaccharides; which reserves determines the resistance of underground shoots to low temperatures and prevents the frost damage to underground meristems, whereas the levels of other phytohormones (IAA, ABA, and GA) significantly decreased at this period. In the autumn, the optimum temperatures for the rhizome growth shifted to low above-zero temperatures, reflecting the adaptation of morphogenetic processes related to the bud formation. The authors conclude that the temperature depression rather than the accumulation of growth inhibitors is the basic factor determining rhizome exogenous dormancy.     

Embryonic Tissue Interactions as the Basis for Morphological Change in Evolution

Phenotypic changes over geological time must result from alterationsin the morphogenetic mechanisms associated with organogenesis.Recent advances in our understanding of such mechanisms suggestthat there are certain patterns of metabolic activity and organellesynthesis which are present in many different cell lineagesat different times during embryonic development, and that thisubiquity of genomic potential is available for expression atany time. Microevolutionary sequences of morphological changeprobably result from modulations of quantitative aspects oforganogenesis, e.g., rates of cell proliferation, or cell density.It is also possible that certain macroevolutionary steps ("neomorphs")may result from qualitative changes in the developmental programs,and such events underly "ultimate refinement" of morphologicaladaptation. The selection pressures involved in these differentsequences of morphological change "see" embryonic processesin different ways. This thesis is illustrated with referenceto the evolutionary history of the tetrapod limb.     

Heritability of regeneration in tissue cultures of sweet potato (Ipomoea batatas L.)

Summary A population of open-pollinated progeny from 12 parents, and the 12 parents, was surveyed for in vitro growth and regeneration characteristics. Four different tissue culture procedures involving different media and the use of different explants to initiate the cultures were used. Petiole explants from young leaves were used as explants for initiation of callus cultures. These were evaluated for callus growth rate, friability, and callus color and texture, before transferring to each of three different regeneration media for evaluation of morphogenetic potential. Small shoot tips also were used to initiate callus cultures, which were evaluated for the same growth characteristics and transferred to growth-regulator free regeneration media. Regeneration occurred through root or shoot regeneration or through embryogenesis. Tissue culture treatment effects, as well as genotypic effects, were highly significant in determining: the types of callus produced, callus growth rates, color and texture on the two types of media used for the second and third subcultures. The family x treatment interaction was generally not statistically significant, affecting only callus color. Estimates of narrow sense heritability for callus growth rate in both the second and third subcultures were high enough (0.35 and 0.63, respectively) for the evaluation of parental lines for selection procedures. These characteristics were also the only early culture callus traits that were consistently correlated with later morphogenesis of the cultures. They were negatively correlated with root or shoot regeneration. The occurence of somatic embryogenesis was not correlated with early callus growth characteristics. Genetic and treatment effects were highly significant in the evaluation of morphogenetic potential, through root or shoot regeneration, or through embryogenesis. Regeneration of all types was of low frequency for all procedures, expressed in 11% of the cultures of the total population.Paper No. 9906 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC 27695-7601, USA. From a thesis submitted by the senior in partial fulfillment of the requirements for the Ph.D. degree     

Analyzing growth components in trees

Observed growth, as given, for instance, by the length of successive annual shoots along the main axis of a plant, is mainly the result of two components: an ontogenetic component and an environmental component. An open question is whether the ontogenetic component along an axis at the growth unit or annual shoot scale takes the form of a trend or of a succession of phases. Various methods of analysis ranging from exploratory analysis (symmetric smoothing filters, sample autocorrelation functions) to statistical modeling (multiple change-point models, hidden semi-Markov chains and hidden hybrid model combining Markovian and semi-Markovian states) are applied to extract and characterize both the ontogenetic and environmental components using contrasted examples. This led us in particular to favor the hypothesis of an ontogenetic component structured as a succession of stationary phases and to highlight phase changes of high magnitude in unexpected situations (for instance, when growth globally decreases). These results shed light in a new way on botanical concepts such as "phase change" and "morphogenetic gradient".     

Bone morphogenetic protein signaling in prostate cancer cell lines

Prostate cancer is the most commonly diagnosed malignancy in men and is often associated with bone metastases. Prostate cancer bone lesions can be lytic or schlerotic, with the latter predominating. Bone morphogenetic proteins (BMPs) are a family of growth factors, which may play a role in the formation of prostate cancer osteoblastic bone metastases. This study evaluated the effects of BMPs on prostate cancer cell lines. We observed growth inhibitory effects of BMP-2 and -4 on LNCaP, while PC-3 was unaffected. Flow cytometric analysis determined that LNCaP cell growth was arrested in G(1) after bone morphogenetic protein-2 treatment. Treatment of LNCaP and PC-3 with BMP-2 and -4 activated downstream signaling pathways involving SMAD-1, up-regulation of p21(CIP1/WAF1) and changes in retinoblastoma (Rb) phosphorylation. Interestingly, bone morphogenetic protein-2 treatment stimulated a 2.7-fold increase in osteoprotegerin (OPG), a molecule, which inhibits osteoclastogenesis, production in PC-3.     

The Bio-Logic and machinery of plant morphogenesis

Morphogenesis (the development of organic form) requires signal-trafficking and cross-talking across all levels of organization to coordinate the operation of metabolic and genomic networked systems. Many biologists are currently converging on the pictorial conventions of computer scientists to render biological signaling as logic circuits supervising the operation of one or more signal-activated metabolic or gene networks. This approach can redact and simplify complex morphogenetic phenomena and allows for their aggregation into diagrams of larger, more "global" networked systems. This conceptualization is discussed in terms of how logic circuits and signal-activated subsystems work, and it is illustrated for examples of increasingly more complex morphogenetic phenomena, e.g., auxin-mediated cell expansion, entry into the mitotic cell cycle phases, and polar/lateral intercellular auxin transport. For each of these phenomena, a posited circuit/subsystem diagram draws rapid attention to missing components, either in the logic circuit or in the subsystem it supervises. These components must be identified experimentally if each of these basic phenomena is to be fully understood. Importantly, the power of the circuit/subsystem approach to modeling developmental phenomena resides not in its pictorial appeal but in the mathematical tools that are sufficiently strong to reveal and quantify the synergistics of networked systems and thus foster a better understanding of morphogenesis.     

Mechanisms of growth and morphogenesis of hydroid polyps as revealed by time lapse microcinematography

By means of time lapse microcinematography, parameters of growth fluctuations in hydroid polyps Obelia and Dynamena were improved, the pulse pattern of morphogenetic processes was shown, the "antiphase" phenomenon was established in the growth fluctuations of adjacent rudiments of Dynamena. In the phase of rudiment stretching, the length of ectodermal epithelial-muscular cells reduces and their orientation changes, thus leading to the displacement of the whole cellular "column" in the distal direction. In the phase of rudiment partial shortening, endodermal cells loose and lengthen, their internal ends displace in the proximal direction and their external ends slide rapidly in the distal direction with respect to hydrotheca. Changes in the form of rudments arise as a direct mechanical result of periodical contractions of cells densely packed in the epithelial layer. On the basis of these data, morphogenetic processes in hydroid polyps related to the appearance and development of folds and to the rudiment flexures are analyzed.     

Statistical Parameters Reflecting Morphogenetic Capacity of Soft Spring Wheat Calluses

Callus cultures of soft spring wheat were subcultured without separation into explants to follow the line one excised embryo–one callus. This approach revealed the following statistical correlations. Within every cultivar of Triticum aestivum L. and within a row of cultivars arranged in ascending order according to the frequency of embryogenic callus formation, positive correlations (at P = 95) were found between the proliferative activity of callus cells and the frequency of embryogenic callus formation. A reliable intraspecies correlation (significant at P = 95) between multiple regenerations of plants from calluses and the tillering trait (bushiness) of donor plants was also found. We assessed the importance of various statistical parameters of callus cultures for preliminary estimation of morphogenesis efficiency at early stages of culturing. Frequencies of callusogenesis and the growth curves for randomly selected calluses turned out to be noninformative characteristics, unless the morphogenetic activity of calluses was taken into account. The following statistical parameters were found to correlate with the morphogenetic capacity of wheat calluses: gradually increasing coefficients of variation in fresh weight of primary calluses, a larger callus size, and higher fresh weight gain in potentially morphogenetic calluses.     

Growth and Development of Isolated Tips of <Emphasis Type="Italic">Neurospora crassa</Emphasis> Hyphae in a Sorbitol-Containing Medium

It is known that the replacement of easily utilizable glucose with sorbitol in a medium activates a large number of repressed genes and metabolic changes in Neurospora crassa, which manifest themselves at the cellular level in a considerable vacuolization of the cytoplasm. The study of the morphological parameters and growth characteristics of isolated apical fragments of N. crassa hyphae showed that, in sorbitol-containing medium, the isolation from the parent mycelium causes the same disturbances in the coordination of elongation, branching, and septation as those described by us earlier for the glucose-containing medium. The metabolic changes caused by the carbon source replacement do not affect the hyphal-segment size, the distance from the growth point to the first septum, and the morphology and distribution of nuclei.     

The influence of the cost of growth on ectotherm metabolism

A new model of ectothermic growth and metabolism is proposed. This model differs from most earlier models in representing explicitly the contribution of the "cost of growth" to ectotherm metabolism. It is shown that the cost of growth may constitute between 17 and 29% of the metabolism of an "average" ectotherm population. Furthermore, the metabolism of an "average" growing ectotherm may be between 40 and 79% greater than that of a non-growing ectotherm. As many environmental factors induce changes in metabolic rates of this magnitude, it is suggested that many factors which cause changes in metabolic rates do so indirectly by altering growth rates. In particular, it is suggested that body size, food availability and temperature often indirectly influence metabolic rates through their effects on growth rates, rather than by directly determining metabolic rates as has usually been assumed.     

Analysis of metabolic network based on conservation of molecular structure

Recent work has revealed much about chemical reactions inside hundreds of organisms as well as universal characteristics of metabolic networks, which shed light on the evolution of the networks. However, characteristics of individual metabolites have been neglected. For example, some carbohydrates have structures that are decomposed into small molecules by metabolic reactions, but coenzymes such as ATP are mostly preserved. Such differences in metabolite characteristics are important for understanding the universal characteristics of metabolic networks. To quantify the structure conservation of metabolites, we defined the "structure conservation index" (SCI) for each metabolite as the fraction of metabolite atoms restored to their original positions through metabolic reactions. As expected, coenzymes and coenzyme-like metabolites that have reaction loops in the network show a higher SCI. Using the index, we found that the sum of metabolic fluxes is negatively correlated with the structure preservation of metabolite. Also, we found that each reaction path around high SCI metabolites changes independently, while changes in reaction paths involving low SCI metabolites coincide through evolution processes. These correlations may provide a clue to universal properties of metabolic networks.     

Microtubular cytoskeleton and root morphogenesis

Although the microtubular cytoskeleton of plant cells is important in maintaining the direction of cell growth, its natural lability can be harnessed in such a way that new growth axes are permitted. In these circumstances, the system which fabricates the cytoskeleton is presumably responsive to morphogenetic information originating from outside the cell. Spatial patterns of hormonal and metabolic signals within the tissue or organ that house the responsive cells are one possible source of this information. However, a contrasting source takes the form of biophysical information, such as the supracellular patterns of stresses and strains.We examined the microtubular cytoskeleton in roots of tomato and maize to test the assumption that the cortical microtubular array of each cell would have a particular orientation relative to the cell's position within the growth field of the root apex. Accordingly, each intracellular cortical array was mapped to the overall pattern of cells within the apex. In certain areas of the meristem, the arrays seemed to be more variable than elsewhere. These are sites where morphogenetic decisions are taken, usually involving a change in the plane of cell division. Roots which have suffered disturbance to their physical structure (e.g. removal of the root cap), or which had been exposed to low temperatures or treated with certain chemicals (e.g. inhibitors of nuclear division or DNA synthesis), exhibited new patterns of microtubular arrays which in turn predicted novel patterns of cell division. In all these circumstances, the arrays showed consistent alterations within distinct regions of the root-e.g. in the quiescent centre and also in a group of cells just behind the quiescent centre, at the boundary between cortex and stele. These altered arrays indicate that there are supracellular domains in which the microtubules respond to morphogenetic signals. Studies such as these reinforce the concept of microtubule lability and the inherent responsiveness of the microtubular system to external and internal stimuli. However, at present there is no indication of how the morphogenetic programme of the root is set up in the first place. Probably, this is established and stabilized early in embryogenesis and is then perpetuated by the prevailing metabolic and biophysical conditions. The microtubules of the cytoskeleton can be regarded as intracellular automata which not only participate in mitosis and cytokinesis but also ensure the realization of an organogenetic programme. Should the root confront circumstances which temporarily destabilize this programme, the prevailing growth field is sufficiently robust to ensure that the microtubular system is attracted back to the stable, pre-existing state capable of reinstating normal morphogenesis. H Lambers Section editor     

Relationship between metabolism, sex and reproductive tactics in young Atlantic salmon (Salmo salar L.)

Atlantic salmon can differ markedly in their growth and in the timing of reproductive maturation, leading to the dramatic contrast between the large anadromous adults and the diminutive mature male parr. This study examined the growth rates, anatomical and physiological characteristics of parr during the adoption of their discrete life histories to ascertain whether these properties can explain tactic choice. To minimise the impact of habitat differences upon these attributes, salmon were reared in the laboratory until 1.5years of age, when the "decisions" to undergo smoltification or to mature as parr had been taken. At 1.5years, both males and females showed bimodal size-frequency distributions. Neither the population of origin nor the paternal reproductive tactic influenced the "decision" to mature or the growth trajectories. Growth rate (% massday(-1) during their final 10months) and the % male and female offspring in the upper modal group were strongly correlated and varied markedly among families. Mean growth rate per family was negatively correlated with mean metabolic rate per family at emergence. Growth rate decreased as a function of parr size in January and the growth rates of upper modal fish were displaced upwards relative to those of lower modal fish. Most males in the smaller size mode matured, whereas all other fish began smoltification. Mature male parr did not differ from similarly sized female pre-smolt in routine metabolic rate, but these smaller fish had higher metabolic rates than larger male and female pre-smolts. However, mature parr differed markedly from similarly sized females and from larger male and female pre-smolts in possessing higher oxidative and lower glycolytic capacities in muscle. Overall, these data are consistent with the interpretation that growth rates dictate the distribution of parr between upper and lower modal groups. Individuals from faster growing families would be more likely to pass the threshold for smoltification and to accelerate growth, whereas those from slower growing families would remain in the lower mode. The use of metabolic capacities, e.g. metabolic rate, was linked with modal group, whereas muscle oxidative capacity was linked with male maturity. Mean family metabolic rate at emergence was negatively linked with mean growth during the subsequent year, suggesting that metabolic efficiency facilitates growth and eventually smoltification.     

Root apical meristems ofAllium porrum L. as affected by arbuscular mycorrhizae and phosphorus

Summary Arbuscular mycorrhizal (AM) fungi significantly improve plant growth in soils with low phosphorus availability and cause many changes in root morphology, similar to those produced by increased P nutrition, mainly depending on root apex size and activity. The aim of this work was to discriminate between the morphogenetic role of AM fungi and P in leek (Allium porrum L.) by feeding mycorrhizal and nonmycorrhizal plants with two nutrient solutions containing 3.2 or 96 M P and examining specific parameters related to adventitious root apices (apex size, mitotic cycle, and RNA synthesis). The results showed that AM fungi blocked meristem activity as indicated by the higher percentages of inactive apices and metaphases in the apical meristem of mycorrhizal plants, whereas the high P supply lengthened the mitotic cycle without blocking the apices, resulting in steady, slow root growth. The possible involvement of abscisic acid in the regulation of root apex activity is discussed.Abbreviations ABA abscisic acid - AM arbuscular mycorrhizae - CI and CII nonmycorrhizal control plants grown with low or high phosphorus concentration - MI and MII mycorrhizal plants grown with low or high phosphorus concentration - PGR plant growth regulator     

Thermochemical characteristics of 2,4-dichlorophenol degrading strain Pseudomonas GT241-1 of growth metabolism by microcalorimetry

By using LKB-2277 Bioactivity Monitor, ampoule method, the heat output of the growth metabolism of a 2.4-dichlorophenol degrading bacteria strain, Pseudomonas strain GT241-1, has been determined at 30 degrees C. From the thermogenic curves, it can be established that thermokinetic equation of their growth metabolism is Pt = Pt = 0 exp(k(m) t), dP/dt = k(m)P1, with the order of growth metabolism n = 1. The experimental results indicate that the relationship between the metabolic power (P) and the cell concentration (C), and relationship between the metabolic power of each cell (P0) and the cell concentration can be characterized by the following thermal equation: C = a + kP, InC = a' + k'P0 or dC/dP0 = KC1. The order of the P0-C equation n is also 1. These results are very significant in environmental sciences, biology and thermochemistry.     

Integrative network analysis reveals active microRNAs and their functions in gastric cancer

Background

Ralstonia eutropha H16, found in both soil and water, is a Gram-negative lithoautotrophic bacterium that can utillize CO₂ and H₂ as its sources of carbon and energy in the absence of organic substrates. R. eutropha H16 can reach high cell densities either under lithoautotrophic or heterotrophic conditions, which makes it suitable for a number of biotechnological applications. It is the best known and most promising producer of polyhydroxyalkanoates (PHAs) from various carbon substrates and is an environmentally important bacterium that can degrade aromatic compounds. In order to make R. eutropha H16 a more efficient and robust biofactory, system-wide metabolic engineering to improve its metabolic performance is essential. Thus, it is necessary to analyze its metabolic characteristics systematically and optimize the entire metabolic network at systems level.

Results

We present the lithoautotrophic genome-scale metabolic model of R. eutropha H16 based on the annotated genome with biochemical and physiological information. The stoichiometic model, RehMBEL1391, is composed of 1391 reactions including 229 transport reactions and 1171 metabolites. Constraints-based flux analyses were performed to refine and validate the genome-scale metabolic model under environmental and genetic perturbations. First, the lithoautotrophic growth characteristics of R. eutropha H16 were investigated under varying feeding ratios of gas mixture. Second, the genome-scale metabolic model was used to design the strategies for the production of poly[R-(-)-3hydroxybutyrate] (PHB) under different pH values and carbon/nitrogen source uptake ratios. It was also used to analyze the metabolic characteristics of R. eutropha when the phosphofructokinase gene was expressed. Finally, in silico gene knockout simulations were performed to identify targets for metabolic engineering essential for the production of 2-methylcitric acid in R. eutropha H16.

Conclusion

The genome-scale metabolic model, RehMBEL1391, successfully represented metabolic characteristics of R. eutropha H16 at systems level. The reconstructed genome-scale metabolic model can be employed as an useful tool for understanding its metabolic capabilities, predicting its physiological consequences in response to various environmental and genetic changes, and developing strategies for systems metabolic engineering to improve its metabolic performance.