Lesions in thighs from hunted Brown Hares (<Emphasis Type="Italic">Lepus europaeus</Emphasis>) and microflora under vacuum-packaging storage

In two surveys, thighs of a total of 137 hunted hares were tested for the presence of intramuscular shots and femur fractures, which were detected in 42.7% and 29.2% of 274 thighs, respectively. Femur fractures were significantly associated with the presence of intramuscular shots. In the second survey (46 hares), 92 thighs were grouped into three categories, “A” (no fractures, no intramuscular shot), “B” (one intramuscular shot), and “C” (multiple shots and hematoma), with 49.0%, 33.6%, and 17.4%, respectively. Category “C” was found unfit for human consumption. During 7-day storage of vacuum-packed “A” and “B” thighs, total aerobic counts increased from initially 3.3 ± 0.3 (mean ± SD) and 4.1 ± 0.6 log cfu/g by ca. 2 log units when stored at 3–4°C, whereas the increase was clearly <1 log unit at 0°C. In comparison to temperature, differences between “A” and “B” category were less pronounced. Similar dynamics were observed for Enterobacteriaceae. In all categories, muscle pH values (mean = 5.83) were similar. It is concluded that storage at temperatures of ca. 4°C, although in compliance with EU legislation, does not afford keeping microbial contaminants in check, and thus will not preserve microbiological quality of vacuum-packed hare meat.     

Final thermal preference in parthenogenetic females of Daphnia magna straus (Crustacea: Cladocera) acclimated to various temperatures

The final thermal preference FTP) range in parthenogenetic females of cladoceran Daphnia magna was assessed by “acute” and “chronic” methods. The first method included 4-month acclimation to different temperatures in the range of 14.2 ± 0.7 to 27.1 ± 0.3°C; the “chronic” method was characterized by long-term acclimation to +20°C. Two ranges of FTP were found for D. magna, 13.3–15.4°C and 20.2–26.2°C. The thermal preference of daphnids and the temperature of acclimation were correspondingly linearly. The range of FTP was independent of the season. The searching activity of D. magna rose in April, when the FTP range increased, and the FTP was less pronounced.     

Adventitious bud regeneration from leaf and cotyledon explants of Chinese hawthorn (<Emphasis Type="Italic">Crataegus pinnatifida</Emphasis> Bge. var. <Emphasis Type="Italic">major</Emphasis> N.E.Br.)

Hawthorn (Crataegus spp.) is an important plant with a long history as an ornamental and a source of medicine. A protocol is outlined for adventitious bud regeneration from leaf and cotyledon explants of Chinese hawthorn (C. pinnatifida Bge. var. major N.E.Br.). Adventitious buds were induced on both the leaves of sprouting winter buds and the leaves of in vitro plants, but the percentage of bud regeneration from leaves of in vitro plants was very low—less than 6%. On N6 medium supplemented with 31.08 μM BA and 9.67 μM NAA, the percentages of bud regeneration from leaves of sprouting winter buds of cultivars “Liaohong” and “Qiujinxing” were 31.4% and 17.6%, respectively. The regeneration abilities of three kinds of cotyledon explants, immature cotyledon, mature cotyledon, and cotyledon leaf, were compared. The percentage of bud regeneration from cotyledon leaves was higher. On MS media supplemented with 4.44 μM BA and 4.54–9.08 μM TDZ, the percentages of bud regeneration from cotyledon leaves of cultivars “Qiujinxing” and “Xiajinxing” were 27.7 ± 7.8% and 20.1 ± 4.7%, respectively, and the numbers of buds per explant were 5.9 ± 1.6 and 3.2 ± 0.7, respectively. On B5 medium supplemented with 2.22 μM BA, 2.32 μM Kn, and 0.57 μM IAA, adventitious buds grew quickly and 80–100% of buds developed into shoots. The shoots rooted successfully with the two-step rooting method. Ninety days after transplantation, more than 80% plants were survived. This system of adventitious bud regeneration from leaf and cotyledon explants could be useful for the genetic transformation and polyploidization of Chinese hawthorn.     

Trp203 mutation in GroEL promotes a self-association reaction: a hydrodynamic study

A combination of sedimentation equilibrium and sedimentation velocity in the analytical ultracentrifuge is used to investigate the hydrodynamic integrity and increased self-association interactions of the mutant GroEL Y203W when compared to the wild-type GroEL molecule, which may be derived from increased hydrophobic exposure caused by the mutation. Sedimentation velocity has revealed that three distinct species were present throughout the concentration ranges used, corresponding to 14-mer (GroEL “super monomer”) and 28-mer (“super dimer”) subunit compositions with a small amount of 42-mer (“super trimer”), which, from the relative concentration of each species, would give an estimated weight average molecular weight of (1.0 ± 0.1) × 10⁶ Da. Sedimentation equilibrium gave an apparent weight average molecular weight (M _w,app) of (910,000 ± 5000) Da, which is in agreement with these findings. These results are in contrast to wild-type GroEL which, in excellent agreement with the previous findings of Behlke and co-workers, revealed a single species with an M _w,_app of (805,000 ± 5200) Da and a sedimentation coefficient s ⁰ _20,w of (21.6 ± 0.3) S. We therefore conclude that the tryptophan mutation at the Y203 location causes a significant degree of self-association of the GroEL 14-mer assembly (with dimer and trimer present). These findings would appear to correlate well with the findings of Gibbons et al., who showed an increase in hydrophobic exposure due to this mutation. Received: 4 January 2000 / Revised version: 5 April 2000 / Accepted: 5 April 2000     

Thermotaxis and selection of a wintering site in the Ajime-loach, <Emphasis Type="Italic">Niwaella delicata</Emphasis>

The hypothesis that the Ajime-loach, Niwaella delicata, is guided to groundwater seepages by a positive thermotaxis in autumn, was tested by a field investigation and aquarium-based experiments. A total of 763 individuals of N. delicata were captured from October to November in a groundwater trap in the Yasu River, Shiga Prefecture. Niwaella delicata began to be captured as the temperature of the surface water fell to 15.8° ± 1.1°C (mean ± SD) and that of the groundwater to 15.5° ± 0.9°C. Groundwater was often warmer than surface water at night or occasionally all day, and the difference in temperature reached a maximum of 1.3°C at the night on 5 November. For the diel pattern of captures, nocturnal capture was higher than diurnal capture when the groundwater was warmer at night and colder during the daytime, whereas both diurnal and nocturnal captures were high when the groundwater was always warmer than the surface water. The aquarium-based experiments showed that N. delicata choose warmer water, ranging from 18.4° to 22.2°C, just before the capture period in the Yasu River, and are sensitive to differences in water temperature of 1.3° ± 0.1°C. Although the present results broadly support the hypothesis, a part of the results indicates that water temperature gradients may not be the only factor involved in the groundwater selection of N. delicata.     

Species and material considerations in the formation and development of microalgal biofilms

The development of microalgal biofilms has received very limited study despite its relevance in the design of photobioreactors where film growth may be advantageous for biomass separation or disadvantageous in fouling surfaces. Here, the effects of species selection, species control, and substrate properties on biofilms of Scenedesmus obliquus and Chlorella vulgaris were investigated. Experiments were conducted in batch culture and in continuous culture modes in a flow cell. Cell growth was monitored using confocal laser scanning microscopy and gravimetrically. Species selection and species control had significant effects on biofilm development. On non-sterile wastewater, C. vulgaris shifted from primarily planktonic (23.7% attachment) to primarily sessile (79.8% attachment) growth. The biofilms that developed in non-sterile conditions were thicker (52 ± 19 μm) than those grown in sterile conditions (7 ± 6 μm). By contrast, S. obliquus attained similar thicknesses (54 ± 31 and 53 ± 38 μm) in both sterile and non-sterile conditions. Neither species was able to dominate a non-sterile biofilm. The effect of substrate surface properties was minimal. Both species grew films of similar thickness (∼30 μm for S. obliquus, <10 μm for C. vulgaris) on materials ranging from hydrophilic (glass) to hydrophobic (polytetrafluoroethylene). Surface roughness created by micropatterning the surface with 10 μm grooves did not translate into long-term increases in biofilm thickness. The results indicate that species selection and control are more important than surface properties in the development of microalgal biofilms.     

Chaetoceros resting spores in the Gerlache Strait, Antarctic Peninsula

The formation of resting spores in diatoms is a common phenomenon in neritic environments. Here we report on resting spores of the genus Chaetoceros associated with a layer of increased chlorophyll fluorescence, at a depth of more than 200 m, north of Brabant Island and in Wilhelmina Bay, southeast coast of the Gerlache Strait (64°41.0′S, 62°0.5′W). Six species of Chaetoceros were identified by the morphology and size of the resting spores. Given that Chaetoceros spp., both in vegetative cells and as resting spores, are commonly found in Antarctic coastal surface waters, their location at depth could represent the pelagic “waiting” or “seeding” populations mentioned for other environments. Received: 25 November 1996 / Accepted: 16 November 1997     

Life and death near a windy oasis

We propose a simple experiment to study delocalization and extinction in inhomogeneous biological systems. The nonlinear steady state for, say, a bacteria colony living on and near a patch of nutrient or favorable illumination (“oasis”) in the presence of a drift term (“wind”) is computed. The bacteria, described by a simple generalization of the Fisher equation, diffuse, divide A→A + A, die A→ 0, and annihilate A + A→ 0. At high wind velocities all bacteria are blown into an unfavorable region (“desert”), and the colony dies out. At low velocity a steady state concentration survives near the oasis. In between these two regimes there is a critical velocity at which bacteria first survive. If the “desert” supports a small nonzero population, this extinction transition is replaced by a delocalization transition with increasing velocity. Predictions for the behavior as a function of wind velocity are made for one and two dimensions. Received: 3 August 1998 / Revised version: 17 July 1999 / Published online: 4 July 2000     

Enumeration of bacteria from a Trichodesmium spp. bloom of the Eastern Arabian Sea: elucidation of their possible role in biogeochemistry

The carbon-flux via algal bloom events involves bacteria as an important mediator. The present study, carried out during the spring inter-monsoon month of April 2008 onboard CRV Sagar Manjusha-06 in the Eastern Arabian Sea, addresses the bloom-specific flow of carbon to bacteria via chromophoric dissolved organic matter (CDOM). Eleven stations monitored were located in the coastal, shelf and open-ocean areas off Ratnagiri (16°59′N, 73°17′E), Goa (15°30′N, 73°48′E) and Bhatkal (13°58′N, 74°33′E) coasts. Visible bloom of “saw-dust” color in the Ratnagiri shelf were microscopically examined and the presence of cyanobacteria Trichodesmium erythraeum and T. thieabautii with cell concentrations as high as 3.05 × 10⁶ trichomes L⁻¹ was recorded. Total bacterial counts (TBC) varied between 94.09 × 10⁸ cells L⁻¹ in the bloom to 1.34 × 10⁸ cells L⁻¹ in the non-bloom area. Chromophoric dissolved organic matter (CDOM) concentrations averaged 2.27 ± 3.02 m⁻¹ (absorption coefficient 325 nm) in the bloom to 0.28 ± 0.07 m⁻¹ in the non-bloom waters respectively. CDOM composition varied from a higher molecular size with lower aromaticity in the bloom to lower molecular size and increased aromaticity in the non-bloom areas respectively. Strong positive relationship of TBC with Chlorophyll a (R ² = 0.65, p < 0.01) and CDOM concentrations (R ² = 0.8373, p = 0.01) in the bloom area indicated hydrolysis and/or uptake of CDOM by bacteria. Absorption by mycosporine-like amino acid palythene (λ _max = 360 nm) was recorded in the filtrate of bloom. Morphotypes of Trichodesmium-associated bacteria revealed a higher frequency of Gram-positive rods. The role of bacteria in relation to changing CDOM nature and as a factor in affecting oxygen content of the water column is discussed in context of the Arabian Sea.     

Characterization of the thermal tolerances of forest ants of New England

Characterization of thermal tolerances of ants, which are both abundant and important in most terrestrial ecosystems, is needed since thermal constraints can inform how a species may respond to local climatic change. Here we identified the thermal tolerances of 16 common ant species of the Northeastern United States and determined relationships between body size, desiccation, and thermal tolerance among species. We hypothesized that maximum heat tolerances of these species would differ and be related to body size and capacity to resist desiccation. We identified four distinct groups of species belonging to one of three subfamilies, Dolichoderinae, Formicinae, or Myrmicinae, with different maximum thermal tolerances. Group “a” had a mean thermal tolerance of approximately 43°C (±1°C), group “b” had a mean thermal tolerance of 40°C (±1°C), group “c” had a mean thermal tolerance of 38°C (±0°C), and group “d” had a mean thermal tolerance of 36°C (±0°C). Groups “a” and “d” consisted of a single species (in the subfamilies Myrmicinae and Formicinae, respectively), while groups “b” and “c” were a mix of species in the subfamilies Myrmicinae, Formicinae, and Dolichoderinae. In the subfamily Formicinae, thermal tolerance increased with body size and critical water content, a metric of desiccation tolerance. In contrast, in the subfamily Myrmicinae, higher thermal tolerance was correlated with intermediate body size and lower critical water content. These findings suggest that the two dominant subfamilies in Northeastern deciduous forests have different relationships between body size, capacity to tolerate desiccation, and thermal tolerances across species. This variation in thermal tolerance suggests that climatic change may impact species differently.     

Effects of hypercapnia on blood-gas and acid-base status in the white sturgeon, Acipenser transmontanus

The effect of environmental hypercapnia on respiratory and acid-base variables was studied in white sturgeon, Acipenser transmontanus. Blood PCO₂, PO₂, pH, hemoglobin concentration, and plasma lactate, glucose, catecholamines and cortisol were measured first under normocapnia (water PCO₂ < 0.5 Torr, 1 Torr = 133.32 Pa), then under hypercapnia (25–35 Torr) and a final return to normocapnia at 19 ± 0.5 °C. Acute (≤ 2h) hypercapnia significantly increased arterial PCO₂ (8-fold increase), ventilation frequency (2-fold increase), plasma HCO₃ ⁻ (2.3-fold) and decreased arterial pH (to 7.15 ± 0.02). After 24 h, norepinephrine, epinephrine and cortisol, were significantly increased, and arterial pH reached its nadir (7.10 ± 0.03). During the 72- and 96-h-periods, arterial PCO₂ (24 ± 4.4 Torr) and ventilatory frequency (105 ± 5 breaths min⁻¹) stabilized, HCO₃ ⁻ reached its apparent maximum (23.6 ± 0.0 mmol⁻¹), glucose decreased by 32%, and pH increased significantly to 7.31 + 0.03. The return to normocapnia completely restored arterial PCO₂ (2.5 ± 0.14 Torr), HCO₃ ⁻ (7.4 ± 0.59 mmol · l⁻¹), ventilation frequency (71 ± 7 breaths · min⁻¹), and pH (7.75 ± 0.04). Overall, hypercapnia produced a respiratory acidosis, hyperventilation, a transient norepinephrine “spike”, and increased plasma catecholamines, cortisol, and arterial PO₂. The respiratory acidosis was only partially compensated (35% pH restoration) 96 h after the onset of hypercapnia and resulted in a significantly decreased blood-O₂ affinity (Bohr effect), as determined by construction of in vitro blood O₂ equilibrium curves at 15 °C and 20 °C. Prolonged exposure to hypercapnia may lead to acid-base disturbances and negatively affect growth of white sturgeon. Accepted: 17 August 1997     

Embryonic Chicken Trachea as a New In Vitro Model for the Investigation of Mucociliary Particle Clearance in the Airways

Mucociliary clearance (MC) is an important defense mechanism of the respiratory system to eliminate inhaled and possibly noxious particles from the lung. Although the principal mechanics of MC seem to be relatively clear there are still open questions regarding the long-term clearance of particles. Therefore, we have developed a new set-up based on embryonic chicken trachea (ECT) to investigate mucociliary particle clearance in more detail. ECT was placed in an incubation chamber after carbon particles were applied and tracked using optical microscopy. The aim of the study was to validate this model by investigating the impact of temperature, humidity and drugs on particle transport rates. Particles were transported reproducibly along the trachea and clearance velocity (2.39 ± 0.25) mm/min was found to be in accordance to data reported in literature. Variation in temperature resulted in significantly reduced MC: (0.40 ± 0.12) mm/min (20 °C); (0.42 ± 0.10) mm/min (45 °C). Decreasing humidity (99–60%) had no significant effect on MC, whereas reduction to 20% humidity showed a significant influence on particle clearance. The use of different cilio- and muco-active drugs (Propranolol, Terbutalin, N-acetylcysteine) resulted in altered MC according to the pharmacological effect of the substances: a concentration dependent decrease of MC was found for Propranolol. From our results we conclude that this model can be employed to investigate MC of particles in more detail. Hence, the model may help to understand and identify decisive physico-chemical parameters for MC and to answer open questions regarding the long-term clearance phenomenon. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Thermal ecology of the Australian agamid Pogona barbata

This study compares the thermal ecology of male bearded dragon lizards (Pogona barbata) from south-east Queensland across two seasons: summer (1994–1995) and autumn (1995). Seasonal patterns of body temperature (T _b) were explored in terms of changes in the physical properties of the thermal environment and thermoregulatory effort. To quantify thermoregulatory effort, we compared behavioral and physiological variables recorded for observed lizards with those estimated for a thermoconforming lizard. The study lizards' field T _bs varied seasonally (summer: grand daily mean (GDM) 34.6 ± 0.6°C, autumn: GDM 27.5 ± 0.3°C) as did maximum and minimum available operative temperatures (summer: GDM T _max 42.1 ± 1.7°C, T _min 32.2 ± 1.0°C, autumn: GDM T _max 31.7 ± 1.2°C, T _min 26.4 ± 0.5°C). Interestingly, the range of temperatures that lizards selected in a gradient (selected range) did not change seasonally. However, P. barbata thermoregulated more extensively and more accurately in summer than in autumn; lizards generally displayed behaviors affecting heat load nonrandomly in summer and randomly in autumn, leading to the GDM of the mean deviations of lizards' field T _bs from their selected ranges being only 2.1 ± 0.5°C in summer, compared to 4.4 ± 0.5°C in autumn. This seasonal difference was not a consequence of different heat availability in the two seasons, because the seasonally available ranges of operative temperatures rarely precluded lizards from attaining field T _bs within their selected range, should that have been the goal. Rather, thermal microhabitat distribution and social behavior appear to have had an important influence on seasonal levels of thermoregulatory effort. Received: 28 April 1997 / Accepted: 29 December 1997     

Chitosan and Glyceryl Monooleate Nanostructures Containing Gemcitabine: Potential Delivery System for Pancreatic Cancer Treatment

The objectives of this study are to enhance cellular accumulation of gemcitabine with chitosan/glyceryl monooleate (GMO) nanostructures, and to provide significant increase in cell death of human pancreatic cancer cells in vitro. The delivery system was prepared by a multiple emulsion solvent evaporation method. The nanostructure topography, size, and surface charge were determined by atomic force microscopy (AFM), and a zetameter. The cellular accumulation, cellular internalization and cytotoxicity of the nanostructures were evaluated by HPLC, confocal microscopy, or MTT assay in Mia PaCa-2 and BxPC-3 cells. The average particle diameter for 2% and 4% (w/w) drug loaded delivery system were 382.3 ± 28.6 nm, and 385.2 ± 16.1 nm, respectively with a surface charge of +21.94 ± 4.37 and +21.23 ± 1.46 mV. The MTT cytotoxicity dose-response studies revealed the placebo at/or below 1 mg/ml has no effect on MIA PaCa-2 or BxPC-3 cells. The delivery system demonstrated a significant decrease in the IC50 (3 to 4 log unit shift) in cell survival for gemcitabine nanostructures at 72 and 96 h post-treatment when compared with a solution of gemcitabine alone. The nanostructure reported here can be resuspended in an aqueous medium that demonstrate increased effective treatment compared with gemcitabine treatment alone in an in vitro model of human pancreatic cancer. The drug delivery system demonstrates capability to entrap both hydrophilic and hydrophobic compounds to potentially provide an effective treatment option in human pancreatic cancer.     

Water spray cooling during handling of feedlot cattle

Activities involved in receiving or working (e.g., sorting, dehorning, castration, weighing, implanting, etc.) of feedlot cattle cause an increase in body temperature. During hot weather the increased body temperature may disrupt normal behaviors including eating, which can be especially detrimental to the well-being and performance of the animals. Sprinkle cooling of animals has been successfully employed within the pen; however, added moisture to the pens’ surface increases odor generation from the pen. A study was conducted to investigate the effectiveness of a single instance of wetting an animal within the working facility instead of in the pen, which could potentially provide extra evaporative cooling to offset the added heat produced by activity. Sixty-four cross-bred heifers were assigned to one of eight pens on the basis of weight. On four separate occasions during hot conditions (average temperature 28.2 ± 1.9°C, 29.1 ± 2.0°C, 28.9 ± 3.0°C, and 26.8 ± 1.6°C; with the temperature ranging from 22.6 to 32.5°C during the trials), the heifers were moved from their pens to and from the working facility (a building with a scale and squeeze chute located 160–200 m away). While in the squeeze chute, four of the pens of heifers were sprinkle cooled and the remaining four pens were worked as normal. The heifers that were treated had a body temperature that peaked sooner (31.9 ± 0.63 min compared to 37.6 ± 0.62) with a lower peak body temperature (39.55 ± 0.03°C compared to 39.74 ± 0.03°C), and recovered sooner (70.5 ± 2.4 min compared to 83.2 ± 2.4 min). The treated animals also had a lower panting score, a visual assessment of level of cattle heat stress (1.1 ± 0.2 compared to 1.16 ± 0.2). The behavior measurements that were taken did not indicate a change in behavior. It was concluded that while a single instance of wetting an animal within the working facility did not completely offset the increase in body temperature, it was beneficial to the animals without needing to add water to the pen surface, thus reducing the potential for odor generation.     

Studies on water transport through the sweet cherry fruit surface: characterizing conductance of the cuticular membrane using pericarp segments

Water conductance of the cuticular membrane (CM) of mature sweet cherry fruit (Prunus avium L. cv. Sam) was investigated by monitoring water loss from segments of the outer pericarp excised from the cheek of the fruit. Segments consisted of epidermis, hypodermis and several cell layers of the mesocarp. Segments were mounted in stainless-steel diffusion cells with the mesocarp surface in contact with water, while the outer cuticular surface was exposed to dry silica (22 ± 1 °C). Conductance was calculated by dividing the amount of water transpired per unit area and time by the difference in water vapour concentration across the segment. Conductance values had a log normal distribution with a median of 1.15 × 10⁻⁴ m s⁻¹ (n=357). Transpiration increased linearly with time. Conductance remained constant and was not affected by metabolic inhibitors (1 mM NaN₃ or 0.1 mM carbonylcyanide m-chlorophenylhydrazone) or thickness of segments (range 0.8–2.8 mm). Storing fruit (up to 42 d, 1 °C) used as a source of segments had no consistent effect on conductance. Conductance of the CM increased from cheek (1.16 ± 0.10 × 10⁻⁴ m s⁻¹) to ventral suture (1.32 ± 0.07 × 10⁻⁴ m s⁻¹) and to stylar end (2.53 ± 0.17 × 10⁻⁴ m s⁻¹). There was a positive relationship (r²=0.066**; n=108) between conductance and stomatal density. From this relationship the cuticular conductance of a hypothetical astomatous CM was estimated to be 0.97 ± 0.09 × 10⁻⁴ m s⁻¹. Removal of epicuticular wax by stripping with cellulose acetate or extracting epicuticular plus cuticular wax by dipping in CHCl₃/methanol increased conductance 3.6- and 48.6-fold, respectively. Water fluxes increased with increasing temperature (range 10–39 °C) and energies of activation, calculated for the temperature range from 10 to 30 °C, were 64.8 ± 5.8 and 22.2 ± 5.0 kJ mol⁻¹ for flux and vapour-concentration-based conductance, respectively. Received: 23 March 2000 / Accepted: 28 July 2000     

An initial comparison of tubular netting versus tie–tie methods of cultivation for Kappaphycus alvarezii (Rhodophyta, Solieriaceae) on the south coast of Rio de Janeiro State, Brazil

A new cultivation technique for Kappaphycus alvarezii was used in the Brazilian southeastern coast (23°02′25″ S and 43°53′39″ W), the tubular netting on floating rafts. The tubular net technique (TN) was compared with the current method of tie–tie (TT). After 47 days, the daily growth rate (mean ± SD of TN and TT = 3.4 ± 0.7% day⁻¹), carrageenan yield (mean ± SD of TN and TT = 36 ± 1.3%), gel strength (mean ± SD of TN and TT = 730 ± 114.5 g cm2), and viscosity (mean ± SD of TN and TT = 350 ± 60.4 cP) did not differ between the two techniques (p > 0.05). The amount of time used to plant (TT = 30.2 ± 2.3 min and TN = 13.3 ± 3.4 min) and to harvest the seedlings (TT = 36.2 ± 2.7 min and TN = 17.8 ± 3.7 min) were lower in TN (p < 0.001). It is concluded that TN was more effective than TT, the cultivation management (time rates used to plant and harvest the seedlings) was 53.6% faster, no seedlings were lost, the cost was lower, and an estimated return in 1 year of nearly 20% more than that of the TT technique.     

Fungal endorhizal associates of Equisetum species from Western and Arctic Canada

We describe endorhizal fungi associated with Equisetum species collected from Ellesmere Island (82°N), Axel Heiberg Island (80°N), and from sites in Yukon Territory and the Prairie Provinces (51–67°N). Fungal colonization was assessed using a multiple quantitation microintersect method for lactofuchsin-stained roots examined with wide-field and confocal epifluorescence microscopy. Equisetum roots host abundant and diverse endorhizal fungal associates. For 85 specimens from 14 sites, total colonization averaged 30 ± 3%, range 0–97%. Colonization rates for wide aseptate hyphae characteristic of arbuscular mycorrhizae (5 ± 1%) was significantly less than for fine endophytes (20 ± 3%) or septate endophytes (17 ± 2%). Equisetum spp. are abundant in tundra and an important understory plant in boreal forests, where they are particularly common on burned or disturbed sites. Endorhizal fungi associated with Equisetum may have broad ecological relevance.     

Effect of “Chemical” Hypoxia on the Potassium Conductance of the Membrane of Pheochromocytoma Cells

We studied the effect of “chemical” (induced by the action of sodium thiosulfate, STS) hypoxia on the potassium conductance of the membrane of pheochromocytoma cells. Application of 1 to 10 mM STS decreased in a dose-dependent manner the amplitude of integral potassium current without changes in the voltage dependence of its activation. The concentration dependence of the action of STS on the amplitude of potassium current was estimated using the Boltzmann equation. The value of concentration for 50% inhibition was 2.7 ± 0.2 mM, while the slope coefficient was 0.9 ± 0.2 mM⁻¹. In the presence of 10 mM STS, the decrease in the amplitude of potassium current reached, on average, 55%. Therefore, “chemical” hypoxia influences rather significantly the potassium conductance of the membrane of pheochromocytoma PC12 cells.     

Drug-Cyclodextrin-Vesicles Dual Carrier Approach for Skin Targeting of Anti-acne Agent

In the present study attempt was made for preparation of isotretinoin-hydroxypropyl β cyclodextrin (HP-β-CD) inclusion complex and encapsulate this complex in elastic liposomes to study the effect of dual carrier approach on skin targeting of isotretinoin. The isotretinoin HP-β-CD complex was prepared by freeze-drying method and characterized by IR spectroscopy. The drug and drug-CD complex loaded elastic liposomal formulation were prepared and characterized in vitro, ex-vivo and in vivo for shape, size, entrapment efficiency, no. of vesicles per cubic mm, in vitro skin permeation and deposition study, photodegradation and skin toxicity assay. The transdermal flux for different vesicular formulations was observed between 10.5 ± 0.5 to 13.9 ± 1.6 μg/cm²/h. This is about 15-21 folds higher than that obtained from drug solution (0.7 ± 0.1 μg/cm²/h) and 4-5 folds higher than obtained with drug-CD complex solution (2.7 ± 0.1 μg/cm²/h). The amount of drug deposit was found to increase significantly (p < 0.05) by cyclodextrin complexation (30.1 ± 0.1 μg). The encapsulation of this complex in elastic liposomal formulation further increases its skin deposition (262.2 ± 21 μg). The results of skin irritation study using Draize test also showed the significant reduction in skin irritation potential of isotretinoin elastic liposomal formulation in comparison to free drug. The results of the present study demonstrated that isotretinoin elastic liposomal formulation possesses great potential for skin targeting, prolonging drug release, reduction of photodegradation, reducing skin irritation and improving topical delivery of isotretinoin.