Daily rhythm of body and auricle temperature in goats kept at two different ambient temperatures

In fluctuating environmental temperature, homeotherms are able to maintain stable their body temperature, which however reveals a rhythmic daily pattern as described in literature. Because of the importance of body temperature rhythmicity in the knowledge of thermal homeostasis and as a means to facilitate the study of biological rhythmicity in general, the aim of our study was to assess the influence of two different ambient temperature on the daily rhythmicity of body and auricle temperature in goat (Capra hircus). For our study 6 female adult Maltese goats (18 month old), not pregnant and clinically healthy were used. On each subject body and auricle temperature was recorded during two different periods, of 7 days each, every 3 hours for 24 hours from 07.00 to 04.00, at different environmental temperature (1^st period 18.25 ± 1.48°C, 2^nd period 28.25 ± 2.05°C). The analysis of the obtained result under two ambient temperature indicates the existence of a daily periodicity, with small differences in amplitude and acrophase between the two studied period, both in body and auricle temperature in Maltese breed goat so we can assume that environmental temperature can influence in a significant way the daily pattern of body and auricle temperature.     

Increased capacity for sustained locomotion at low temperature in parthenogenetic geckos of hybrid origin

The evolution of parthenogenesis is typically associated with hybridization and polyploidy. These correlates of parthenogenesis may have important physiological consequences that need be taken into account in understanding the relative merits of sexual and parthenogenetic reproduction. We compared the thermal sensitivity of aerobically sustained locomotion in hybrid/triploid parthenogenetic races of the gecko Heteronotia binoei and their diploid sexual progenitors. Endurance times at low temperature (10 degrees , 12.5 degrees , and 15 degrees C, 0.05 km h(-1)) were significantly greater in parthenogenetic females than in sexual females. Comparison of oxygen consumption rates during sustained locomotion at increasing speeds (0.05, 0.10, 0.15, 0.20, 0.25, and 0.30 km h(-1), 25 degrees C) indicated that parthenogenetic lizards have higher maximum oxygen consumption rates and maximum aerobic speeds than do female sexual geckos. In addition, parthenogenetic geckos showed greater levels of voluntary activity at 15 degrees C than did sexual geckos, although this pattern appears strongest in comparison to male sexual forms. Parthenogenetic lineages of Heteronotia thus have an advantage over sexual lineages in being capable of greater aerobic activity. This result is opposite of that found in prior studies of parthenogenetic teiid lizards (genus Cnemidophorus) and highlights the idiosyncratic nature of phenotypic evolution in parthenogens of hybrid origin.     

Infection, propagation, distribution and stability of plant virus in hairy root cultures

Nicotiana benthamiana hairy root cultures were infected with tobacco mosaic virus (TMV) and used for in vitro plant virus propagation. The roots were infected with TMV by addition of virus to the medium at the same time as root inoculation. Viral accumulation in the biomass was 7-11-fold greater when the initial infection was carried out in B5 medium rather than sodium phosphate buffer; virus accumulation also increased with increasing viral inoculum concentration. The amount of TMV accumulated in the biomass was similar when virus was retained in the medium for the duration of the cultures and when the inoculum virus was removed 23h after addition to the roots. In roots with established infections, the concentration of virus remained relatively constant and did not increase with further root growth. The distribution of virus within individual root mats harvested from shake flasks was not uniform; there was also significant variability in viral accumulation between replicate hairy root cultures. The picture that emerges from this work is that in vitro viral accumulation in hairy root cultures depends strongly on the viral inoculum concentration applied and the initial level of primary infection achieved, even though primary infection by external virus occurs mainly within only the first few hours of exposure to the biomass and is followed by substantial secondary infection by viral progeny within the root tissue.     

Rapid reduction of arsenate in the medium mediated by plant roots

Microbes detoxify arsenate by reduction and efflux of arsenite. Plants have a high capacity to reduce arsenate, but arsenic efflux has not been reported. Tomato (Lycopersicon esculentum) and rice (Oryza sativa) were grown hydroponically and supplied with 10 microm arsenate or arsenite, with or without phosphate, for 1-3 d. The chemical species of As in nutrient solutions, roots and xylem sap were monitored, roles of microbes and root exudates in As transformation were investigated and efflux of As species from tomato roots was determined. Arsenite remained stable in the nutrient solution, whereas arsenate was rapidly reduced to arsenite. Microbes and root exudates contributed little to the reduction of external arsenate. Arsenite was the predominant species in roots and xylem sap. Phosphate inhibited arsenate uptake and the appearance of arsenite in the nutrient solution, but the reduction was near complete in 24 h in both -P- and +P-treated tomato. Phosphate had a greater effect in rice than tomato. Efflux of both arsenite and arsenate was observed; the former was inhibited and the latter enhanced by the metabolic inhibitor carbonylcyanide m-chlorophenylhydrazone. Tomato and rice roots rapidly reduce arsenate to arsenite, some of which is actively effluxed to the medium. The study reveals a new aspect of As metabolism in plants.     

In vitro dual culture of Polymyxa betae in Agrobacterium rhizogenes transformed sugar beet hairy roots in liquid media

Polymyxa betae is a soil-borne protist and an obligate parasite of sugar beet that transmits the beet necrotic yellow vein virus. Sugar beet hairy roots, transformed by Agrobacterium rhizogenes, were inoculated with surface-sterilized root fragments infected by P. betae. After 10 wk in a liquid medium, typical structures of P. betae were observed in this in vitro system. This first in vitro culture of P. betae in liquid medium will contribute to a better understanding of this protist's biology through providing a way to conserve and produce purified isolates of the protist.     

Carbon dioxide improves the growth of hairy roots cultured on solid medium and in nutrient mists

The effect of varying CO₂ concentrations on the growth of beet and safflower hairy roots was measured for tissues cultured in nutrient mists and on solid media in chambers fed mixtures of humidified air supplemented with different CO₂ concentrations. Hairy root tissue grown on solid media in air enriched with CO₂ showed increased growth, as measured by dry weight increases vs air-fed controls. Growth increased with CO₂ enrichment as much as 2.5 times more than the air-fed control for safflower at 1.0% CO₂ and 1.4 times more than the air-fed control for beets at 1.5% CO₂ over a 12-day period. Beet hairy root tissue was also cultured aeroponically in nutrient mists. Beet hairy root cultured aeroponically in nutrient mists enriched with 1.0% CO₂ showed a 15% increase in biomass over a 7-day period vs tissue cultured in nutrient mists (with ambient air) or in shake flasks. The stimulation of root growth via CO₂ enrichment reduced the time required for biomass accumulation.Correspondence to: A. A. DiIorio     

A succinate-oxidising nitrate reductase is located at the plasma membrane of plant roots

Plasma-membrane-bound nitrate reductase (PM-NR) is located in roots and leaves of tobacco (Nicotiana tabacum L. cv. Samsun) and reduces nitrate with NADH as electron donor. When plasma membranes were prepared under specific protecting conditions, a PM-NR of roots was detected that accepts electrons from succinate to reduce nitrate. Comparison between the succinate dehydrogenase of mitochondria and the succinate-oxidising PM-NR of roots indicated that they are two different enzymes. Partial purification of the nitrate reductase forms by anion-exchange chromatography indicated that succinate and NADH supply electrons to the same plasma-membrane-bound protein. Received: 27 March 1997 / Accepted: 9 April 1997     

The first report on the induction of hairy roots in Trapa natans,a unique aquatic plant with photosynthesizing roots

Hairy root cultures are often used to produce valuable metabolites. They are grown on sucrose-rich medium, which is highly susceptible to contamination. Trapa natans is a unique plant with photosynthesizing roots. It is a promising object to obtain photoautotrophic hairy root culture. Protocols for transformation of this species are yet unknown. We report that hairy roots can be induced in aquarium and in vitro cultures of T. natans by agrobacterium-mediated and biolistic transformation. 64 roots were induced by Agrobacterium rhizogenes strain 15834, two roots were obtained using strain K599. Strain A4 was not effective. Biolistics with either amplicons of rol genes and 1301 pCAMBIA plasmid carrying rol genes resulted in the formation of six roots. All these roots contained chloroplasts. This achievement opens a prospect for genetic transformation of T. natans and use of its green photosynthesizing hairy root cultures in production of bioactive substances and in phytoremediation.

     

Survival of Entamoeba and related Amoebae at low temperature. I. Viability of Entamoeba cysts at 4 degrees C

The time of survival at 4°C of mature cysts of six species of Entamoeba was studied. The length of time cysts generally survived storage was E. histolytica 12 weeks, E. moshkovskii 36 weeks, E. terrapinae and E. knowlesi 24 weeks, E. ranarum 25 weeks and E. invadens 7 weeks.     

Effect of intraventricular injection of muscimol on appetite in rats kept at high and temperate ambient temperatures

The central mechanism controlling food intake in response to the change in environmental temperature has been little examined. The GABA agonist, muscimol, was injected into the lateral ventricle of rats which were acclimated to temperate (26 degrees C) and hot (33 degrees C) environments. Muscimol obviously stimulated the feeding behavior of rats in both environments. However, when muscimol was administered at doses of 100 and 250 ng, the food intake at 26 degrees C was greater than that at 33 degrees C. In addition, the stimulating effect of muscimol (250 ng) on food intake at 26 degrees C lasted longer than that at 33 degrees C. These findings suggested that there might be a difference in muscimol metabolism at the two temperatures.     

An improved transformation protocol for studying gene expression in hairy roots of sugar beet (Beta vulgaris L.)

A transformation protocol, based on co-inoculation with two strains of Agrobacterium, Agrobacterium tumefaciens LBA4404 and A. rhizogenes 15834 containing a binary vector with the GUS gene, was established for the induction of transgenic hairy roots from sugar beet (Beta vulgaris L.) explants. It resulted in marked improvement in the formation of hairy roots and the integration of the binary vector T-DNA into the host genome. Of 250 inoculated sugar beet hypocotyls, 84% yielded hairy roots 5–7 days after inoculation, of which 70% were co-transformed with the binary vector T-DNA. To determine stable expression of alien genes in hairy roots, the nematode resistance gene Hs1 ^pro-1 was used as a reporter gene. In addition, molecular marker analysis was applied to monitor stable incorporation of a translocation from the wild beet B. procumbens. The molecular analysis and the nematode (Heterodera schachtii) resistance test in vitro demonstrated that the genomic structure and the expression of the Hs1 ^pro-1 -mediated nematode resistance were well-maintained in all hairy root cultures even after repeated sub-culture. Received: 25 November 1997 / Revision received: 26 May 1998 / Accepted: 15 June 1998     

Effect of low ambient temperature on protein turnover and heat production in chicks

1. Effect of low ambient temperature on protein turnover in the liver and whole body was investigated in chicks together with the contribution of protein synthesis to the total heat production. 2. Both protein synthesis and degradation in the whole body were increased, the latter to a larger extent, at low ambient temperature (LT, 22 degrees C) compared with adequate temperature (AT, 30 degrees C). Liver protein synthesis was not significantly altered by the temperature treatment. 3. The total heat production of LT group was as high as 160% of the AT group. 4. The increased heat production due to enhanced whole-body protein synthesis accounted for only 1.4% of the heat increment in thermogenesis at low ambient temperature, suggesting that protein synthesis would contribute little, if any, to cold-induced thermogenesis in chicks.     

Sporamin-mediated resistance to beet cyst nematodes (Heterodera schachtii Schm.) is dependent on trypsin inhibitory activity in sugar beet (Beta vulgaris L.) hairy roots

Sporamin, a sweet potato tuberous storage protein, is a Kunitz-type trypsin inhibitor. Its capability of conferring insect-resistance on transgenic tobacco and cauliflower has been confirmed. To test its potential as an anti-feedant for the beet cyst nematode (Heterodera schachtii Schm.), the sporamin gene SpTI-1 was introduced into sugar beet (Beta vulgaris L.) by Agrobacterium rhizogenes-mediated transformation. Twelve different hairy root clones expressing sporamin were selected for studying nematode development. Of these, 8 hairy root clones were found to show significant efficiency in inhibiting the growth and development of the female nematodes whereas 4 root clones did not show any inhibitory effects even though the SpTI-1 gene was regularly expressed in all of the tested hairy roots as revealed by northern and western analyses. Inhibition of nematode development correlated with trypsin inhibitor activity but not with the amount of sporamin expressed in hairy roots. These data demonstrate that the trypsin inhibitor activity is the critical factor for inhibiting growth and development of cyst nematodes in sugar beet hairy roots expressing the sporamin gene. Hence, the sweet potato sporamin can be used as a new and effective anti-feedant for controlling cyst nematodes offering an alternative strategy for establishing nematode resistance in crops.     

Intranuclear accumulation of plant tubulin in response to low temperature

Summary. Concurrently with cold-induced disintegration of microtubular structures in the cytoplasm, gradual tubulin accumulation was observed in a progressively growing proportion of interphase nuclei in tobacco BY-2 cells. This intranuclear tubulin disappeared upon rewarming. Simultaneously, new microtubules rapidly emerged from the nuclear periphery and reconstituted new cortical arrays, as was shown by immunofluorescence. A rapid exclusion of tubulin from the nucleus during rewarming was also observed in vivo in cells expressing GFP-tubulin. Nuclei were purified from cells that expressed GFP fused to an endoplasmic-reticulum retention signal (BY-2-mGFP5-ER), and green-fluorescent protein was used as a diagnostic marker to confirm that the nuclear fraction was not contaminated by nuclear-envelope proteins. These purified, GFP-free nuclei contained tubulin when isolated from cold-treated cells, whereas control nuclei were void of tubulin. Furthermore, highly conserved putative nuclear-export sequences were identified in tubulin sequences. These results led us to interpret the accumulation of tubulin in interphasic nuclei, as well as its rapid nuclear export, in the context of ancient intranuclear tubulin function during the cell cycle progression. Correspondence and reprints: Department of Plant Physiology, Faculty of Science, Charles University, Viničná 5, 128 44 Prague 2, Czech Republic.     

Light-induced root hair formation in lettuce (Lactuca sativa L. cv. Grand Rapids) roots at low pH is brought by chlorogenic acid synthesis and sugar

Previously, we reported that chlorogenic acid (CGA) facilitated root hair formation at pH 4.0 in lettuce (Lactuca sativa L. cv. Grand Rapids). Light was essential for this process. In the present study, we determined relationships between CGA, light, and sugar during root hair formation in lettuce seedlings. The amount of CGA increased with white light in intact seedlings. Exogenously applied CGA restored root hair formation in dark-grown intact seedlings at pH 4.0. However, no root hair formation was induced in decapitated seedlings regardless of light exposure and CGA application. Application of sucrose or glucose induced both root hair formation and CGA synthesis in light-grown decapitated seedlings at pH 4.0. Blue light was the most effective for both root hair formation and CGA synthesis when supplied with sucrose to decapitated seedlings. Addition of sucrose and CGA together induced root hair formation at pH 4.0 in dark-grown decapitated seedlings. Results suggest that light induced CGA synthesis from sugar in the roots. Sugar was also required for root hair formation other than starting material of CGA synthesis. In addition, an unknown low pH-induced factor was essential for lettuce root hair formation.