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At least 973 records · Page 54Linked to original sources
PubMed2003

Development of a root feeding system based on a fiber ion-exchange substrate for space plant growth chamber "Vitacycle".

Selecting a plant root nutrient delivery system is one of the key aspects of designing root modules for space plant growth chambers. This article examines a number of the nutrient delivery systems and shows the most suitable technique for providing nutrients to roots in microgravity, which to date are ion-exchange artificial soils. In addition, this article characterizes the ion composition and hydrophysical parameters of a new Russian artificial ion charged fiber substrate, BIONA-V3. The BIONA-V3 substrate is comprised of ion-exchange resin fibers. The experimental data concerning the effects of anionic and cationic components on plant biomass is presented. Preliminary experiments with BIONA-V3 showed that 1 kg of dry BIONA-V3 produces up to 2.4 kg (fresh mass) of cabbage leaf or 180 g of dry plant mass per 1 dm3 of the substrate. Therefore, the root zone volume can be as small as 120 cm3 per plant. Further optimizing the nutrient composition of the resin fibers can increase space plant growth chamber productivity.

Biomass↗
PubMed1998

Effects of microgravity on the growth of Lepidium roots.

The normal growth dynamics of plant roots is partly controlled by the gravitational force. In order to study the detailed growth behavior in absence of gravity, the growth of Lepidium sativum roots was recorded by time lapse photography at 1h intervals in a Spacelab ESA-experiment (IML-2). Plants were germinated and kept in microgravity during the experiments, while control roots were at 1 g with normal static gravistimulation. Extended image analyses allowed new information to be achieved about movements of all parts of the roots, extending earlier published results. Root contours were extracted from the images and divided into 0.6mm segments. Deviation angles were calculated for each root segment, both for the first 8-10 h (phase I) and for the last 6-8 h of the experiment (phase II). For phase I, the present analysis confirmed that the average square deviation increased linearly with time for roots in microgravity, while for roots under 1 g conditions it stayed constant. This was consistent with a random walk hypothesis for the bending pattern. In phase II, roots in microgravity stopped their spontaneous curvatures and showed more straight growth or even diminished the root curvatures that had occurred during phase I. Thus, the growth is distinctly different in the two phases and is thought to be controlled by autotropic reactions in phase II. Root hairs developed when the roots passed into phase II. During phase I, the root growth rates were equal in microgravity and on the ground (0.50 mm h-1 with SE 0.04 and 0.51 mm h-1 with SE 0.03, respectively). In phase II the growth rate on the ground was higher than in microgravity (1.44 mm h-1 with SE 0.10 and 1.07 mm h-1 with SE 0.04 in microgravity). Microgravity conditions, therefore, clearly affect Lepidium root growth: In phase I the bending pattern is random in contrast to the normal straight growth under 1g. In phase II the growth rate is reduced, as compared to the growth rate under 1 g.

Brassicaceae↗
PubMed2005

[Temperature impact on localization of "free" phenolic compounds in the root tissues and deformation of root hairs in pea seedlings inoculated by Rhizobium].

The study was focused on localization of "free" phenolic compounds in pea Pisum sativum L. seedling roots grown at 22 and 8 degrees C 24 h after their inoculation with Rhizobium leguminosarum bv. viceae bacteria. A comparison of phenolic compound distribution along the root in root tissues, and results of observation of root hair development on the root surface, response of root hairs to inoculation, manifesting itself in various deformation degree (bends, twists, ect.) enabled us to reveal differences between roots grown at different temperatures. These differences are basically referred to a sector localized 0-5 mm away from the root tip containing meristematic and extending cells. A distribution of phenolic compounds in sectors with root hairs responding to inoculation by various degrees of contortion practically did not depend on the temperature of plant growth. The evidence provided in the course of this work enabled us to suggest that inhibition of pea root infection at low temperature is caused by decelerated growth processes characteristic of both the root itself and root hairs, as well by a slow increase in the root hair zone.

Pisum sativum↗
PubMed1998

Fine structure and development of dorsal root ganglion neurons and Schwann cells in the newborn opossum Monodelphis domestica.

The aim of these experiments was to determine the state of maturity of dorsal root ganglia and axons in opossums (Monodelphis domestica) at birth and to assess quantitatively changes that occur in early life. Counts made of dorsal root ganglion cells at cervical levels showed that the numbers were similar in newborn and adult animals, approximately 1,600 per ganglion. In cervical dorsal root ganglia of newborn animals, division of neuronal precursors cells had ceased. The number of axons in cervical dorsal roots was similar in newborn and adult animals (about 4,500). For each ganglion cell body, approximately three axons were counted in the dorsal root. At birth, dorsal roots contained several bundles about 30 microns in diameter consisting of small axons (0.05-2 microns in diameter). A few non-neural cells were identified as Schwann cell perikarya, each enclosing a number of neurites. Later, marked changes occurred in Schwann cells and in their relationship to axons in the roots. Thus, at 12 days, an increase occurred in the number of Schwann cells and fibroblasts, and the bundles had enlarged to about 80 microns with little increase in axon diameter (0.1-2 microns). By 18 days, the bundles were larger, and myelination had already started. At 23 days, the dorsal root contained more than 500 myelinated axons that could reach 5 microns in diameter. The adult dorsal root enclosed about 900 myelinated axons. Throughout this time, the relationship between the Schwann cells and axons changed. Together, these results indicate that the number of axons and cell bodies of sensory dorsal root ganglia in opossum do not show major changes after birth. In addition, these results set the stage for quantitative studies of regeneration of dorsal column fibers in injured neonatal opossum nervous system.

Aging↗
PubMed2004

Amine fluoride/stannous fluoride and incidence of root caries in periodontal maintenance patients. A 2 year evaluation.

AIM: The purpose of the present study was to evaluate in a group of periodontal maintenance patients, the effect of using a dentifrice and mouthrinse containing amine fluoride (AmF) and stannous fluoride (SnF2) as compared with a dentifrice and mouthrinse both containing sodium fluoride (NaF) with regard to their root caries experience. MATERIAL: In total, 80 patients who had been treated for moderate-to-severe periodontitis agreed to participate in this study. Subjects received supportive periodontal therapy at regular intervals of 3-4 months for at least a period of 1 year. The patients were randomly divided into two groups: (1) the test group used an AmF/SnF2 dentifrice and mouthrinse and (2) the control group used an NaF-containing dentifrice and mouthrinse. Root caries was recorded at four sites per tooth at baseline and 24 months. RESULTS: An increase in number of the exposed root surfaces was noted for both groups during the experimental period (p<0.05). The mean number of active caries lesions at baseline was 2.1 and 1.8 for the test group and control group, respectively. At 24 months, the corresponding values were 1.8 for the test and 2.2 for the control group. An increase of the mean number of restored surfaces was noted for the AmF/SnF2 group (from 7.3 to 13.4) and the control group (from 7.9 to 14.7) during the course of the study. This increase was found to be statistically significant for both groups in comparison with the baseline values (p< or =0.01). No statistically significant differences were noted between groups. Further analysis of the restored surfaces revealed that the major increase in number of the restorations was associated with restorations involving three to four root surfaces in the same tooth. Molars and premolars were the teeth receiving most new restorations. CONCLUSION: The present study did not detect a difference in terms of root caries development between the two groups. Root caries development is a common finding associated with surfaces developing recession in patients once treated for periodontal problems.

Adult↗