Progressive deceleration in growth as an early sign of delayed puberty in boys

OBJECTIVE: To describe the prepubertal growth pattern in boys with delayed puberty. METHODS: Growth curves for height and height velocity covering the age range 4-14 years were constructed on the basis of retrospectively obtained data in 85 boys with delayed puberty, who attained a normal final height. RESULTS: Between the age of 4 and 14 years the height in this cohort progressively deviated from the normal reference. At the age of 4 years, the height SDS was already significantly lower (median -0.8; p < 0.001) and progressively diminished during childhood, resulting in a median height SDS of -1.1 at the age of 12 years (p < 0.001). The median final height of this cohort (-0.4) was not different from their target height (-0.2). The degree of deceleration in growth during childhood was not determined by birth weight or birth height and did not influence final height. The decline of the height velocity with age in this group of boys with delayed puberty was significantly smaller (p < 0.001) than predicted by the model of Rikken and Wit. CONCLUSION: Late-maturing boys often show a prepubertal deceleration in growth that starts at an early age but that does not affect final height.     

Cell elongation as an inseparable component of growth in terrestrial plants

The review is dedicated to the role of cell elongation in plant growth and morphogenesis. The ratios of cell division to elongation, cell competence for the initiation of elongation, main features of the metabolism of elongating cells, and physiological processes realizing elongation have been considered on the examples of seed germination and growth of roots, stems, and leaves. A special attention was paid to the vacuole as a specific feature of plant cells, pathways of its formation, and its role in maintenance of ion and water homeostasis in the elongating cell. The plant can modify its morphology according to changes in the environmental conditions via cell elongation.     

Cell elongation as an inseparable component of growth in terrestrial plants

The review is dedicated to the role of cell elongation in plant growth and morphogenesis. The ratios of cell division to elongation, cell competence for the initiation of elongation, main features of the metabolism of elongating cells, and physiological processes realizing elongation have been considered on the examples of seed germination and growth of roots, stems, and leaves. A special attention was paid to the vacuole as a specific feature of plant cells, pathways of its formation, and its role in maintenance of ion and water homeostasis in the elongating cell. The plant can modify its morphology according to changes in the environmental conditions via cell elongation.     

Frequency as a property of physiological signals in plants

Abstract. The 'hormone' idea is based on a peculiarly chemical notion of substance and time. Although the chemical view of substance is advanced, its view of time is primitive compared to that of physics. This leads to considerable difficulties when applied to oscillatory systems, such as the nutating hypocotyl. There is evidence of involvement of a wide range of oscillatory systems in plants. In considering the properties of such systems, the possibility of physiological signals based on frequency becomes apparent. Some implications of this possibility for both theory and experimental programmes are discussed.     

Chirality as an inherent general property of matter

A statement has been formulated that chirality is an indispensable inherent property of all material objects, at one level of organization of matter or another. The translation of chirality from one level of material objects to another deserves our attention. The parity violation of weak interactions can be discussed in terms of the homochirality of the pool of fundamental particles, as it translates into optical activity of metal vapors. Individual photons and energy quanta are considered to be chiral entities, too, since they can be separated into beams of circularly polarized radiation. The chiral structure of the universe has been proposed and a method of determining the orientation of the axis of rotation of the universe suggested.     

Invasibility as an emergent property of native metapopulation structure

Biological invasions constitute major threats to global biodiversity. Eco‐evolutionary considerations highlight the importance of contemporary evolution in community responses to bioinvasions. However, effects of metapopulation structure on invasion success have been mostly overlooked even though metapopulation structure determines gene flow and is likely to affect evolutionary processes. Here, we investigate a stepping‐stone model with evolving alien native interaction strengths. We demonstrate analytically that the site of invasion can determine the success of an invading consumer because gene flow and demography of a local resource species interact to obstruct local resource adaptation. Our main results are 1) that invasion success is more likely in genetic sink populations of the native species and 2) that invasion is more likely to occur against the migrational flow of native species. These findings suggest that invasibility is best regarded as an emergent property not only of communities but of entire metapopulations. Since migration networks of aliens and natives are often mismatched due to anthropogenic interference, our results indicate how population structure eases the spread of invasives against the migrational flow of natives.     

Impaired growth in transgenic plants over-expressing an expansin isoform

Expansins are cell wall proteins characterised by their ability to stimulate wall loosening during cell expansion. The expression of some expansin isoforms is clearly correlated with growth and the external application of expansins can stimulate cell expansion in vivo in several systems. We report here the expression of a heterologous expansin coding sequence in transgenic tomato plants (Lycopersicon esculentum Mill.) under the control of a constitutive promoter. In some transgenic lines with high levels of expansin activity extractable from cell walls, we observed alterations of growth: mature plants were stunted, with shorter leaves and internodes, and dark-grown seedlings had shorter and wider hypocotyls than their wild-type counterparts. Examination of hypocotyl sections revealed similar differences at the cellular level: cortical and epidermal cells were shorter and wider than those from wild-type seedlings. The observed stimulation of radial expansion did not compensate for the decreased elongation, and overall growth was reduced in the transgenics. As this observation can seem paradoxical given the known effect of expansins on isolated cell walls, we examined the mechanical behaviour of transgenic tissue. We measured a decrease in hypocotyl elongation in response to acidic pH in the transformants. This result may account for the alterations in cell expansion, and could itself be explained by a reduced susceptibility of transgenic cell walls to expansin action.     

Nuclear Genetic Material as an Initial Substrate of Aging in Animals

General properties of aging in animals are considered on the basis of the literature evidence and the results obtained by the authors of this paper. The existence of a specific aging mechanism is inferred. The operation of this mechanism is controlled not only by genes but also by particular noncoding genomic sequences with variable structure. The beginning of senescence in animals is determined by DNA lesions located in neural cells and probably in a minor genomic fraction. The authors refute the narrow concept of aging as a mechanism increasing the probability of death. Mortality as a continuous process occurring with the probability of 100 percent is an integral attribute of living organisms on the Earth.     

Cortical bone tissue resists fatigue fracture by deceleration and arrest of microcrack growth

Knowledge of kinetics of fatigue crack growth of microcracks is important so as to understand the dynamics of bone adaptation, remodeling, and the etiology of fatigue-based failures of cortical bone tissue. In this respect, theoretical models (Taylor, J. Biomech., 31 (1998) 587-592; Taylor and Prendergast, Proc. Instn. Mech. Engrs. Part H 211 (1997) 369-375) of microcrack growth in cortical bone have predicted a decreasing microcrack growth rate with increasing microcrack length. However, these predictions have not been observed directly. This study investigated microcrack growth and arrest through observations of surface microcracks during cyclic loading (R=0.1, 50-80MPa) of human femoral cortical bone (male, n=4, age range: 37-40yr) utilizing a video microscopy system. The change in crack length and orientation of eight surface microcracks were measured with the number of fatigue cycles from four specimens. At the applied cyclic stresses, the microcracks propagated and arrested in generally less than 10,000 cycles. The fatigue crack growth rate of all microcracks decreased with increasing crack length following initial identification, consistent with theoretical predictions. The growth rate of the microcracks was observed to be in the range of 5x10(-5) to 5x10(-7)mmcycle(-1). In addition, many of the microcracks were observed not to grow beyond 150 microm and a cyclic stress intensity factor of 0.5MNm(-3/2). The results of this study suggest that cortical bone tissue may resist fracture at the microscale by deceleration of fatigue crack growth and arrest of microcracks.     

Identification of microtubule growth deceleration and its regulation by conserved and novel proteins

Microtubules (MTs) are cytoskeletal polymers that participate in diverse cellular functions, including cell division, intracellular trafficking, and templating of cilia and flagella. MTs undergo dynamic instability, alternating between growth and shortening via catastrophe and rescue events. The rates and frequencies of MT dynamic parameters appear to be characteristic for a given cell type. We recently reported that all MT dynamic parameters vary throughout differentiation of a smooth muscle cell type in intact Caenorhabditis elegans. Here we describe local differences in MT dynamics and a novel MT behavior: an abrupt change in growth rate (deceleration) of single MTs occurring in the cell periphery of these cells. MT deceleration occurs where there is a decrease in local soluble tubulin concentration at the cell periphery. This local regulation of tubulin concentration and MT deceleration are dependent on two novel homologues of human cylicin. These novel ORFs, which we name cylc-1 and -2, share sequence homology with stathmins and encode small, very basic proteins containing several KKD/E repeats. The TOG domain–containing protein ZYG-9^TOGp is responsible for the faster polymerization rate within the cell body. Thus we have defined two contributors to the molecular regulation for this novel MT behavior.     

A Large Deep Skin Ulcer as an Initial Manifestation of Systemic Cryptococcosis

Mycopathologia - An 82-year-old woman presented to our hospital with a deep skin ulcer in her right lower limb. Although the skin biopsy showed necrosis and neutrophil infiltration, we could not...     

Siderophores sorbed on Ca-montmorillonite as an iron source for plants

Previous investigations have shown significant sorption of siderophores to the solid phase in soils, and clay surfaces in particular. The ability of plants to utilize Fe from this reservoir is therefore of great interest. This research focused on the ability of the hydroxamate siderophore ferrioxamine B (FOB) sorbed to Ca-montmorillonite – prevailing in soils – to supply Fe to peanuts (Arachis hypogeae L.). Remediation of Fe deficiency by the sorbed siderophore was found to be similar to that by the free (unsorbed) form. The concentration needed to achieve complete remediation of chlorosis was one order of magnitude higher than that of the optimal FeEDDHA [Fe-ethylenediamine-di(o-hydroxyphenylacetic acid)]. Using dialysis tubes, it was shown that Fe uptake from the sorbed siderophore is executed mainly via long-range pathways and does not require close proximity to the plant roots. It was hypothesized that the process involves chelating agents in solution, which transport the Fe from the immobilized siderophore and enable its uptake by the plant. Under calcareous conditions, the ability of the sorbed FOB to supply Fe was significantly impaired, probably as a result of inactivation of the bridging mechanism. Various possible shuttle compounds were examined. EDDHA was found to be a very efficient shuttle compound, which caused complete remediation of Fe deficiency, even under very harsh calcareous conditions. The findings support our hypothesis and imply the effectiveness of a ligand-exchange mechanism to strategy I plants (commonly attributed to strategy II plants). We suggest that the secretion of substances with chelating abilities, which is usually considered a less effective means of Fe acquisition mechanism, takes on more importance in this context.     

Coumarin-related compounds as plant growth inhibitors from two rutaceous plants in Thailand

Chemical investigation of naturally occurring plant growth inhibitors from Rutaceous plants in Thailand led us to identify five 7-methoxycoumarins and one 5,7-dimethoxycoumarin from Murraya paniculata, and six furanocoumarins from Citrus aurantifolia. Of these compounds, murranganon senecioate (1) is a new natural compound found in M. paniculata. Minumicrolin (6) was found to be highly active against the 2nd leaf sheath elongation of rice seedlings.     

Metabolite profiling as an aid to metabolic engineering in plants

The past decade has seen some impressive successes in the metabolic engineering of biotechnologically important plant pathways. However, plant metabolic engineering currently proceeds more by trial and error than by intelligent system design. A change in philosophy away from studying pathways in isolation and towards studying metabolism as a network is necessary. To support this development, improvements in technologies for metabolic analysis, a wider adoption of metabolite-profiling approaches and significant innovations in data analysis methodologies are required.     

Sodium as an essential micronutrient element for some higher plants

Summary Twenty-three species of higher plants were tested for their responses to 0.1 me/l Na₂SO₄ when added to their culture solutions which contained only 0.08 µe/l Na after purification of the salts and water. All the 9 Australian species ofAtriplex developed characteristic sodium-deficiency symptoms similar to those previously observed inAtriplex vesicaria and their dry-weight yields increased significantly on receiving sodium.Sodium increased the dry-weight significantly in one of the four species ofAtriplex not indigenous to Australia but deficiency symptoms were not observed.A significant dry-weight response to sodium was obtained inHordeum vulgare cv. Pallidium.No other species, even in Chenopodiaceae, responded to sodium under the conditions of the experiments. It is concluded that they either have no sodium requirement or their requirement is so small that they obtained adequate sodium for normal growth and development in these trials.