Seasonal changes of the introduced Caulerpa racemosa var. cylindracea (Caulerpales,Chlorophyta) at the northwest limit of its Mediterranean range

A study of the meadows of the invasive Caulerpa racemosa var. cylindracea (Sonder) Verlaque, Huisman et Boudouresque was carried out over one year at Marseilles (Provence, France) where the alga is thriving, probably since 1994, in the cold waters of the north western Mediterranean Sea. At an early phase of colonisation, the C. racemosa meadow is characterized by a patchy distribution pattern. Several years are necessary to obtain a dense and continuous meadow. In one area colonized for more than 4 years, C. racemosa has developed a continuous meadow with wide seasonal variations. Maximum development was reached in autumn (biomass: 82 ± 3 g DW m⁻²; length of stolons: 1162 ± 86 m m⁻²; number of apices: 8360 ± 405 m⁻²; number of erect axes: 20955 ± 1499 m⁻²) and the minimum from winter to early spring (respectively, 0.3 ± 0.1 g DW m⁻²; 3 ± 1 m m⁻²; 220 ± 55 apices m⁻²; 35 ± 15 erect axes m⁻²). Seasonal variations in the growth rate were highly significant. The season of high growth lasted from June to October. The apical growth rate of a stolon reached a maximum of 7.5 ± 0.3 mm day⁻¹ in early October, then began to decrease significantly from the end of October to December, before becoming nearly nil from January to early May. Annual net production rate expressed in terms of stolon length and biomass was estimated as 5801 m m⁻² a⁻¹ and 612 g DW m⁻² a⁻¹, respectively. During the growth period, the turnover rate of the C. racemosa stolons was estimated at from 25 to 46 days. The growth rate was closely correlated to the seawater temperature (R² = 0.83), whereas no significant correlation was found between growth and irradiance. During the growth period, a decrease in temperature rapidly affects the growth rate, which soon recovers its earlier level when the temperature rises again. In winter, the growth rate decreased rapidly with the seasonal drop in the seawater temperature. Grazing by fish (Sarpa salpa and Boops boops) can also affect the growth rate from September to December by consumption of the erect axes and stolon apices, enhancing the ramification of stolons. Seasonal changes at Marseilles are much sharper than those reported for warmer Mediterranean localities (French Riviera, Italy, Croatia): in winter and early spring C. racemosa meadows decreased and locally disappeared, leaving a barren substrate. C. racemosa survives the lower winter seawater temperatures of the north-western Mediterranean Sea probably in the form of zygotes and/or small fragments (rhizoids, stolons, propagules).     

Study of morphological and phenological diversity in chestnut trees (‘Judia’ variety) as a function of temperature sum

Morphological and histological adaptation of chestnut leaves at the different altitudes and edaphoclimate conditions were shown. The study was carried out on Castanea sativa Mill. var. ‘Judia’. The growth range altitudes of ‘Judia’ were between 709 m a.s.l. and 860 m a.s.l. (above sea level), corresponding to a variation in the sum of temperatures (expressed in degree-day values – °D) of 2751 °D to 2316 °D in 2006 and 2338 °D to 1700 °D in 2007, between May and October. In 2007 the thickest leaves (319.9 μm), the highest stomata density (469.1 stomata mm⁻²), one of the largest leaf areas (69.2 cm²) and the highest fruit size (71.7 fruit kg⁻¹) were observed in Alfândega da Fé (759 m a.s.l., 2186 °D, during the May–October period) whereas in 2006 the highest fruit size (86.8 fruit kg⁻¹) was observed in Valpaços (860 m a.s.l., 2316 °D, during the same period).Additionally, the leaves of the trees grown in this locality (Valpaços) displayed one of the largest areas (57.0 cm²). Overall results suggest that annual climate conditions do significantly influence both fruit and leaf biometric characteristics, and that the range of temperatures from 2100 °D to 2300 °D (between May and October) correspond to the optimal temperature sum, which can be ascribed to different places, depending on the year in question. Concerning the molecular characterisation using nuclear microsatellites, the individuals more distant are those from Macedo de Cavaleiros and Alfândega da Fé (genetic distance = 0.227), while the ecotypes with closer similarities were those collected in Murça and Vinhais (genetic identity = 1.171). The current results suggest that the morphological and phenological differences among ecotypes are not related to the small genetic differences, but are simply phenotypic adaptations to diffent climatic conditions.     

Effects of intraspecific competition on growth and photosynthesis of Atriplex prostrata

We investigated the effect of intraspecific competition on growth parameters and photosynthesis of the salt marsh species Atriplex prostrata Boucher in order to distinguish the effects of density-dependent growth inhibition from salt stress. High plant density caused a reduction of 30% in height, 82% in stem dry mass, 80% in leaf dry mass, and 95% in root dry mass. High density also induced a pronounced 72% reduction in leaf area, 29% decrease in length of mature internodes and 50% decline in net photosynthetic rate. The alteration of net photosynthesis paralleled growth inhibition, decreasing from 7.6 ± 0.9 μmol CO₂ m⁻² s⁻¹ at low density to 3.5 ± 0.4 μmol CO₂ m⁻² s⁻¹ at high density, indicating growth inhibition caused by intraspecific competition is mainly due to a decline in net photosynthesis rate. Plants grown at high density also exhibited a reduction in stomatal conductance from 0.7 ± 0.1 mol H₂O m⁻² s⁻¹ at low density to 0.3 ± 0.1 mol H₂O m⁻² s⁻¹ at high density and a reduction in transpiration rate from 6.0 ± 0.3 mmol H₂O m⁻² s⁻¹ at low density to 4.3 ± 0.3 mmol H₂O m⁻² s⁻¹ at high density. Biomass production was inhibited by an increase in plant density, which reduced the rate of photosynthesis, stomatal conductance and leaf area of plants.     

Leaf production and shoot dynamics of Thalassia testudinum by a direct census method

The annual leaf growth and shoot dynamics of Thalassia testudinum were examined in a meadow located near Havana City, Cuba, using direct censuses between January 1995 and January 1996. The net rate of shoot population change, specific shoot recruitment and mortality rates were calculated as the difference between the densities of shoots (tagged or untagged) in consecutive sampling events. The leaf biomass, the daily production, the turnover rate and the rate of leaf biomass loss were also estimated. The estimated mean dry leaf biomass (124.9 ± 9.5 g m⁻²), daily dry leaf production (3.3 ± 0.2 g m⁻² day⁻¹) and turnover rate (2.7 ± 0.1% day⁻¹) were comparable to values previously reported for this species in Cuba and elsewhere. The production of leaves and shoots were higher in spring, declined towards mid summer, and showed the minimum values in January. Shoot recruitment prevailed over shoot mortality from January to March and from July to August, whereas most of the annual shoot mortality occurred between May and July and between August and October. The meadow examined was in close demographic balance along the study period. The results demonstrate that direct census provides reliable estimates of rapid shoot dynamics in T. testudinum.     

Diurnal exchanges of CO2 and CH4 across the water–atmosphere interface in a water chestnut meadow (Trapa natans L.)

CH₄ and CO₂ fluxes across the water–atmosphere interface were measured over a 24 h day–night cycle in a shallow oxbow lake colonized by the water chestnut (Trapa natans L.) (Lanca di Po, Northern Italy). Only exchanges mediated by macrophytes were measured, whilst gas ebullition was not considered in this study. Measurements were performed from 29 to 30 July 2005 with short incubations, when T. natans stands covered the whole basin surface with a mean dry biomass of 504 ± 91 g m⁻². Overall, the oxbow lake resulted net heterotrophic with plant and microbial respiration largely exceeding carbon fixation by photosynthesis. The water chestnut stand was a net sink of CO₂ during the day-light period (−60.5 ± 8.5 mmol m⁻² d⁻¹) but it was a net source at night (207.6 ± 6.1 mmol m⁻² d⁻¹), when the greatest CO₂ efflux rate was measured across the water surface (28.2 ± 2.4 mmol m⁻² h⁻¹). The highest CH₄ effluxes (6.6 ± 1.8 mmol m⁻² h⁻¹) were determined in the T. natans stand during day-time, whilst CH₄ emissions across the plant-free water surface were greatest at night (6.8 ± 2.1 mmol m⁻² h⁻¹). Therefore, we assumed that the water chestnut enhanced methane delivery to the atmosphere. On a daily basis, the oxbow lake was a net source to the atmosphere of both CO₂ (147.1 ± 10.8 mmol m⁻² d⁻¹) and CH₄ (116.3 ± 8.0 mmol m⁻² d⁻¹).     

GLP-1(32–36)amide,a novel pentapeptide cleavage product of GLP-1, modulates whole body glucose metabolism in dogs

We have previously demonstrated in human subjects who under euglycemic clamp conditions GLP-1(9–36)amide infusions inhibit endogenous glucose production without substantial insulinotropic effects. An earlier report indicates that GLP-1(9–36)amide is cleaved to a nonapeptide, GLP-1(28–36)amide and a pentapeptide GLP-1(32–36)amide (LVKGR amide). Here we study the effects of the pentapeptide on whole body glucose disposal during hyperglycemic clamp studies. Five dogs underwent indwelling catheterizations. Following recovery, the dogs underwent a 180 min hyperglycemic clamp (basal glucose +98 mg/dl) in a cross-over design. Saline or pentapeptide (30 pmol kg⁻¹ min⁻¹) was infused during the last 120 min after commencement of the hyperglycemic clamp in a primed continuous manner. During the last 30 min of the pentapeptide infusion, glucose utilization (M) significantly increased to 21.4 ± 2.9 mg kg⁻¹ min⁻¹compared to M of 14.3 ± 1.1 mg kg⁻¹ min⁻¹ during the saline infusion (P = 0.026, paired t-test; P = 0.062, Mann–Whitney U test). During this interval, no significant differences in insulin (26.6 ± 3.2 vs. 23.7 ± 2.5 μU/ml, P = NS) or glucagon secretion (34.0 ± 2.1 vs. 31.7 ± 1.8 pg/ml, P = NS) were observed. These findings demonstrate that under hyperglycemic clamp studies the pentapeptide modulates glucose metabolism by a stimulation of whole-body glucose disposal. Further, the findings suggest that the metabolic benefits previously observed during GLP-1(9–36)amide infusions in humans might be due, at least in part, to the metabolic effects of the pentapeptide that is cleaved from the pro-peptide, GLP-1(9–36)amide in the circulation.     

Behavioral thermoregulation and critical thermal limits of giant keyhole limpet Megathura crenulata (Sowerby 1825) (Mollusca; Vetigastropoda)

The thermoregulatory behavior of the giant keyhole limpet Megathura crenulata was determined in a horizontal thermal gradient during the day at 18.9 °C and 18.3 °C for the night. The final preferendum determined for giant keyhole limpets was of 18.6±1.2 °C.Limpets' displacement velocity was 10.0±3.9 cm h⁻¹ during the light phase and 8.4±1.6 cm h⁻¹ during the dark phase. The thermotolerance (measured as CTMax at 50%) was determined in a keyhole limpet in three acclimation temperatures 17, 20, and 23 °C. Limpets were subjected to water increasing temperatures at a rate of 1 °C every 30 min, until they detached from the substrate. The critical thermal maximum at 50% was 27.2, 27.9 and 28.3 °C respectively.     

Shifts in thermoregulatory strategy during ontogeny in harp seals (Pagophilus groenlandicus)

Heat balance can be difficult for young and/or small animals in polar regions because environmental conditions in combination with small body size or physiological immaturity can increase heat loss. We investigated how thermoregulatory patterns change with ontogeny in 5 age classes of harp seal (Pagophilus groenlandicus) from birth to post-molt to further understand the timing of thermoregulatory development in relation to their potential vulnerability to ongoing fluctuations in the extent and stability of Arctic pack ice. We measured changes in the amount, conductivity, and resistance of the seal pups׳ insulative layers (blubber and fur), the potential for endogenous heat-generation by shivering (muscle enzyme activity), and nonshivering thermogenesis (NST; brown adipose tissue (BAT) uncoupling protein 1 (UCP1) expression and mitochondrial density). There was no significant difference in blubber conductivity among age classes, though the amount of blubber insulation significantly increased from birth to weaning. Pelage conductivity was low (0.12±0.01 W m⁻¹ °C⁻¹) except in 9-day old pups (0.40±0.08 W m⁻¹ °C⁻¹); the significantly higher conductivity may signal the beginning of the molt, and this age group may be the most vulnerable to early water entry. Citrate synthase activity significantly increased (49.68±3.26 to 75.08±3.52 μmol min⁻¹ g wet weight⁻¹) in the muscle; however it is unlikely that increasing a single enzyme greatly impacts heat generation. BAT of younger pups contained UCP1, though expression and mitochondrial density quickly declined, and the ability of pups to produce heat via NST was lost by weaning. While total thermal resistance did not differ, neonatal and early nursing animals gained the majority of their thermal resistance from lanugo (82.5±0.03%); however, lanugo is not insulative when wet, and NST may be important to maintain euthermia and dry the coat if early immersion in water occurs. By late nursing, blubber seems sufficient as insulation (75.87±0.01% of resistance after 4 weeks), but high conductivity of fur may be responsible for retention of UCP1 expression. Weaned animals rely on blubber insulation, and no longer need NST, as wetted fur is no longer a threat to euthermia.     

Cell proliferation and survival in the mating circuit of adult male hamsters: Effects of testosterone and sexual behavior

The transient actions of gonadal steroids on the adult brain facilitate social behaviors, including reproduction. In male rodents, testosterone acts in the posterior medial amygdala (MeP) and medial preoptic area (MPOA) to promote mating. Adult neurogenesis occurs in both regions. The current study determined if testosterone and/or sexual behavior promote cell proliferation and survival in MeP and MPOA. Two experiments were conducted using the thymidine analog BrdU. First, gonad-intact and castrated male hamsters (n = 6/group) were compared 24 h or 7 weeks after BrdU. In MeP, testosterone-stimulated cell proliferation 24 h after BrdU (intact: 22.8 ± 3.9 cells/mm², castrate: 13.2 ± 1.4 cells/mm²). Testosterone did not promote cell proliferation in MPOA. Seven weeks after BrdU, cell survival was sparse in both regions (MeP: 2.5 ± 0.6 and MPOA: 1.7 ± 0.2 cells/mm²), and was not enhanced by testosterone. In Experiment 2, gonad-intact sexually-experienced animals were mated weekly to determine if regular neural activation enhances cell survival 7 weeks after BrdU in MeP and MPOA. Weekly mating failed to increase cell survival in MeP (8.1 ± 1.6 vs. 9.9 ± 3.2 cells/mm²) or MPOA (3.9 ± 0.7 vs. 3.4 ± 0.3 cells/mm²). Furthermore, mating at the time of BrdU injection did not stimulate cell proliferation in MeP (8.9 ± 1.7 vs. 8.1 ± 1.6 cells/mm²) or MPOA (3.6 ± 0.5 vs. 3.9 ± 0.7 cells/mm²). Taken together, our results demonstrate a limited capacity for neurogenesis in the mating circuitry. Specifically, cell proliferation in MeP and MPOA are differentially influenced by testosterone, and the birth and survival of new cells in either region are not enhanced by reproductive activity.     

Population densities,group size and biomass of ungulates in a lowland tropical rainforest forest of the eastern Himalayas

Large ungulate population monitoring is a crucial wildlife management tool as ungulates help in structuring and maintaining the large carnivore populations. Reliable data on population status of major ungulate prey species are still non-existent for most of the protected areas in the Indian part of the eastern Himalayan biodiversity hotspot. Twenty transects were monitored over a period of three years (2009–2011) totaling 600 km with an average length of 2 km. The estimated mean density of ungulates was 17.5 km⁻² with overall density of 48.7 km⁻². The wild pig Sus scrofa had the highest density (6.7 ± 1.2 km⁻²) among all the prey species followed by barking deer Muntiacus muntjak (3.9 ± 0.6 km⁻²), sambar Rusa unicolor (3.8 ± 0.5) and gaur Bos gaurus (3.5 ± 0.9 km⁻²). The estimated total ungulate biomass density was 2182.56 kg km⁻². This prey biomass can support up to 7.2 tigers per 100 km⁻². However, with two other sympatric carnivores sharing the same resources, the actual tiger numbers that can be supported will be lower. The estimated minor prey species was 31 km⁻² significantly 30.6% crop damages were reported by wild pig (p = 0.01) and 35.4% was elephant (p = 0.004). This data on ungulate densities and biomass will be crucial for carnivore conservation in this understudied globally significant biodiversity hotspot.     

Partitioning of latent heat flux at a northern peatland

The partitioning of latent heat flux (Q_E) to vascular plant and moss surface components was assessed for a Sphagnum-dominated bog with a hummock–hollow surface having a sparse canopy of low shrubs. Results from porometry and eddy covariance measurements of Q_E showed evaporation from the moss surface ranged from greater than 50% of total Q_E early in the growing season to less than 20% after a dry period toward the end of the growing season. Both soil moisture and vapour pressure deficit (D_a) affected this partitioning with drier moss and peat, lower water table, and smaller D_a all reducing moss Q_E. Daily maximum moss Q_E ranged from greater than 200 W m⁻² early in the growing season to less than 100 W m⁻² during a dry period. In contrast, vascular contribution to total Q_E increased over the season from a daily maximum of about 150 W m⁻² to 250 W m⁻² due to increase in leaf area by leaf replacement and emergence and to drying of the moss surface. Porometry results showed average daily maximum conductance from bog shrubs was near 8 mm s⁻¹. These conductance values were smaller than those reported for vascular plants from more nutrient-rich wetlands. The effect of increases in D_a on vascular Q_E were moderated by decreases in stomatal conductance. At constant available energy, vascular leaf conductance was reduced by as much as 2 mm s⁻¹ and moss surface conductance was enhanced by up to 3 mm s⁻¹ by large D_a. Considering vascular and non-vascular water transport characteristics and frequency of water table position and given the observed variations of Q_E partitioning with water table location and moss and peat water content, it is suggested that modelling efforts focus on how dry hummocks and wet hollows each contribute to Q_E, especially as related to D_a and soil moisture dynamics.     

Kinetic analysis of photosynthetic growth and photohydrogen production of two strains of Rhodobacter Capsulatus

Two mutants of Rhodobacter Capsulatus (JP91 and IR3), a photosynthetic purple non-sulfur bacterium, were grown in a batch photobioreactor under illumination with 30 mmol l⁻¹ dl-lactate and 5 mmol l⁻¹ l-glutamate as carbon and nitrogen source, respectively. Bacterial growth was measured by monitoring the increase in absorbance at 660 nm. The photosynthetic growth processes under different cultivated temperatures are well fitted by a specific logistic model to analyze the kinetics of photosynthetic growth of two strains, thus the apparent growth rates (k) of these photosynthetic bacteria, the variations of cell dry weight (CDW) as well as their relationship with temperature are obtained. In present work, k is (0.1465 ± 0.0146), (0.2266 ± 0.0207) and (0.3963 ± 0.0257) h⁻¹ for JP91 and (0.1117 ± 0.0122), (0.1218 ± 0.0133) and (0.2223 ± 0.0152) h⁻¹ for IR3 at 26, 30 and 34 °C, respectively. And the difference between CDW_max and CDW₀ is (0.8997 ± 0.0097), (0.8585 ± 0.0093) and (0.9241 ± 0.0099) g l⁻¹ for JP91 and (0.8167 ± 0.0089), (0.7878 ± 0.0086) and (0.8358 ± 0.0091) g l⁻¹ for IR3 at 26, 30 and 34 °C, respectively. Also real-time monitoring of hydrogen production rates is acquired by recording the flow rates of photohydrogen for these two strains under different temperatures. The effects of temperature on the bacteria growth, hydrogen production capability and substrate conversion efficiency are discussed based on these results. The most preferment temperature, 30 °C, showed good substrate conversion efficiency of 52.7 and 68.2% for JP91 and IR3, respectively.     

Effect of ligand congeniality on energy transfer reaction between photo-excited tris(bipyridine)ruthenium(II) and chromate(III) complexes in aqueous solutions

Energy-transfer rate-constants from photo-excited [Ru(N–N)₃]²⁺ (N–N = 2,2′-bipyridine (bpy), 4,4′-dimethyl-2,2′-bipyridine (4dmb), 5,5′-dimethyl-2,2′-bipyridine (5dmb)) to [Cr(O–O)₃]³⁻ (O–O²⁻ = ox²⁻ ((COO⁻)₂), mal²⁻ (CH₂(COO⁻)₂)) and [Cr(CN)₆]³⁻ in encounter complexes were evaluated in aqueous solutions containing alkali metal ion. The rate constant depends on the molecular size of the ruthenium(II) complex: 1.8 × 10⁸ s⁻¹ for [Ru(bpy)₃]²⁺ (molecular radius, r = 5.8 Å), 1.4 × 10⁸ s⁻¹ for [Ru(5dmb)₃]²⁺ (r = 6.1 Å) and 0.96 × 10⁸ s⁻¹ for [Ru(4dmb)₃]²⁺ (r = 6.7 Å) in the system of [Ru(N–N)₃]²⁺–[Cr(ox)₃]³⁻ in aqueous solution. However, the rate constant is much more sensitive to the chromate(III) complex than to ruthenium(II) complex; 1.8 × 10⁸ s⁻¹ and 0.43 × 10⁸ s⁻¹ for [Cr(ox)₃]³⁻ (r = 4.0 Å) and [Cr(mal)₃]³⁻ (r = 4.2 Å) in the [Ru(bpy)₃]²⁺–[Cr(O–O)₃]³⁻ systems, respectively. We conclude that the congeniality between the donor’s and acceptor’s ligands in encounter complex plays an important role in energy transfer in aqueous solution.     

LC–MS quantification of parthenolide and cholinesterase inhibitory potential of selected Tanacetum L. (Emend. Briq.) taxa

The acetonitrile extracts of various Tanacetum L. (Emend. Briq.) taxa from Turkey as well as parthenolide, a sesquiterpene lactone found in Tanacetum species as active substance were investigated for their inhibitory activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), the key enzymes in pathogenesis of Alzheimer's disease, at 100 μg mL⁻¹ using ELISA microplate assay. Most of the extracts displayed a remarkable AChE inhibition where the leaf of Tanacetum argenteum subsp. flabellifolium had the highest inhibition (96.68 ± 0.35%). The extracts had moderate inhibition toward BChE, among which the stem of Tanacetum argyrophyllum var. argyrophyllum-1 exerted the best inhibition (63.81 ± 3.64%). However, parthenolide exhibited low inhibition against both of the enzymes. Total flavonoid content of the extracts was determined spectrophotometrically. Parthenolide, a sesquiterpene lactone, was quantified in these taxa by LC–MS and the leaf of T. argenteum subsp. argenteum possessed the richest parthenolide amount (2.261 ± 0.002%), while most of the species screened were found to contain the required percentage (0.2% minimum) by European Pharmacopeia.     

Potential of dendrochronology in assessing carbon sequestration rates of Vitellaria paradoxa in southern Mali,West Africa

This study aimed to investigate the applicability of dendrochronology for assessing the growth dynamics and response to climate variability and to estimate the aboveground carbon stock and carbon sequestration potential of Vitellaria paradoxa in southern Mali. Twenty stem disks were collected from three land-use types (parklands, fallows and protected areas) in Koutiala and Yanfolila districts. We combined a standard dendrochronological approach with biomass allometric equations to estimate the growth and carbon stocks. The results showed that V. paradoxa forms distinct growth ring boundaries but most of the disks from parklands did not successfully cross-date due to management operations like pruning. The tree-ring width showed a significant standardized coefficient of regression with rainfall (r² = 0.66, p < 0.001) but insignificant correlation with temperature. One-way analysis of variance showed no significant difference (p > 0.05) for C-sequestration as well as for carbon stocks in aboveground biomass for both land-use types and sites. Mean values of the amount of C-sequestered in Yanfolila were 0.112 ± 0.0.065 Mg C ha⁻¹ yr⁻¹ in parklands, 0.075 ± 0.018 Mg C ha⁻¹ yr⁻¹ in fallows and 0.064 ± 0.028 Mg C ha⁻¹ yr⁻¹ in protected areas. In Koutiala, the values were 0.068±0.020 Mg C ha⁻¹ yr⁻¹ in the parklands and 0.053 ± 0.017 Mg C ha⁻¹ yr⁻¹ in the fallows. These results clearly indicate that dendrochronology can be applied to assess growth and carbon sequestration potential of V. paradoxa. These results also suggest that climate change could affect the growth and carbon sequestration potential of V. paradoxa. Given the limited size of our sample, figures on the amount of carbon are indicative calling for applying the tested approaches to larger samples and also to other tree species in West Africa.     

Stress responses and specific metal exclusion on mine soils based on germination and growth studies by Australian golden wattle

We reported the Australian golden wattle as a copper stabilizer in abandoned copper mine soils earlier. Here we investigate to confirm this plant’s suitability to grow on metal contaminated mine soils based on stress indication. The seeds of Acacia pycnantha collected from mining area were germinated after heat and no heat treatment on two types of irrigation. The daily irrigated and heat treated seeds gave up to 85% germination on sandy soil. The A. pycnantha was grown under greenhouse condition in six different soils collected from abandoned copper mine at Kapunda in South Australia. Among the six soil samples, soil-1 with the highest copper concentration produced 2.05 mmol g⁻¹ tissue of proline. Proline expression was prominent in more saline soils (1, 5 and 6) having electrical conductivity (EC) 1184, 1364 and 1256 μS, respectively. Chlorophyll a, b and carotenoid levels in plants showed a gradually decreasing trend in all the soils as experiment progressed. The plants grown on soil sample-1, containing 4083 ± 103 mg kg⁻¹ of copper resulted in 18 ± 2 mg kg⁻¹ accumulation in its leaf. The calcium accumulation was significant up to 11648 ± 1209 mg kg⁻¹ in leaf. Although pore water samples showed higher Cu concentration in soils, an increased mobility of arsenic and lead was observed in all the soil samples. Our experiment points out the need for proper monitoring of revegetation processes to avoid revegetation and reclamation failure.     

Expression and purification of recombinant feline interferon in the baculovirus-insect larvae system

Feline interferons (FeIFNs) are cytokines with antiviral, antitumor and immunomodulatory functions used as therapeutic agents in a variety of veterinary diseases. In this work, FeIFN-α7 and FeIFN-α7xArg containing eight residues of arginine were expressed in Sf9 cells and insect larvae. At 4 days post-infection (dpi), the concentrations of FeIFN-α7 and FeIFN-α7xArg in suspension culture were (1.28 ± 0.15) × 10⁶ U ml⁻¹ and (1.3 ± 0.2) × 10⁶ U ml⁻¹ respectively. The maximum expression levels of FeIFN-α7 and FeIFN-α7xArg were (3.7 ± 0.2) × 10⁶ U ml⁻¹ and (3.5 ± 0.4) × 10⁶ U ml⁻¹ at 2 dpi in Rachiplusia nu larvae and (1.1 ± 0.2) × 10⁶ U ml⁻¹ and (1.0 ± 0.15) × 10⁶ U ml⁻¹ at 5 dpi in Spodoptera frugiperda larvae respectively. R. nu was a better host for FeIFN-α7 and FeIFN-α7xArg expression. The 8xArg tag did not affect the biological activity of FeIFN-α7 and was useful to promote the FeIFN-α7xArg adsorption on ion exchange chromatography (IEC), allowing its purification in a single step from supernatant culture and R. nu larvae. FeIFN-α7xArg was purified from the larval extract with a yield of 70% and a purification factor of 25 free of viruses. We conclude that R. nu larvae are new low-cost hosts for the expression of recombinant FeIFN-α7.     

Volatile fatty acids accumulation and rhamnolipid generation in situ from waste activated sludge fermentation stimulated by external rhamnolipid addition

The solubilization and acidification of waste activated sludge (WAS) were apparently enhanced by external rhamnolipid (RL) addition. The maximum solute carbohydrate concentrations increased linearly from 48 ± 5 mg COD L⁻¹ in the un-pretreated WAS (blank) to 566 ± 19 mg COD L⁻¹, and protein increased from 1050 ± 8 to 3493 ± 16 mg COD L⁻¹ at RL dosage of 0.10 g g⁻¹ TSS. The highest VFAs concentration peaked at 3840 mg COD L⁻¹ at RL dosage of 0.04 g g⁻¹ TSS, which was 4.24-fold higher than the blank test. RL was generated in situ during WAS fermentation when external RL was added. It was detected that RL concentration was increased from initial 880 ± 92 mg L⁻¹ to 1312 ± 7 mg L⁻¹ at the end of 96 h with RL dosage of 0.04 g g⁻¹ TSS, which was increased to 1.49-fold. Meanwhile, methane production was notably reduced to a quite low level of 2.0 mL CH₄ g⁻¹ VSS, showing effective inhibition of methanogens by RL (58.8 mL CH₄ g⁻¹ VSS in the blank). In addition, the activity of hydrolytic enzymes (protease and α-glucosidase) was enhanced accordingly. VFAs accumulation and RL generation in situ demonstrated that the additional RL substantially performed enhanced biological effects for waste activated sludge fermentation.     

Patch dynamics of the Mediterranean seagrass Posidonia oceanica: Implications for recolonisation process

Patch dynamics of the Mediterranean slow-growing seagrass Posidonia oceanica was studied in two shallow sites (3–10 m) of the Balearic Archipelago (Spain) through repeated censuses (1–2 year⁻¹). In the sheltered site of Es Port Bay (Cabrera Island), initial patch density (October 2001) was low: 0.05 patches m⁻², and the patch size (number of shoots) distribution was bimodal: most of the patches had less than 6 shoots or between 20 and 50 shoots. Mean patch recruitment in Es Port Bay (0.006 ± 0.002 patches m⁻² year⁻¹) exceeded mean patch loss (0.001 ± 0.001 patches m⁻² year⁻¹), yielding positive net patch recruitment (0.004 ± 0.003 patches m⁻² year⁻¹) and a slightly increased patch density 3 years later (July 2004, 0.06 patches m⁻²). In the exposed site of S’Estanyol, the initial patch density was higher (1.38 patches m⁻², August 2003), and patch size frequency decreased exponentially with size. Patch recruitment (0.26 patches m⁻² year⁻¹) and loss (0.24 patches m⁻² year⁻¹) were high, yielding a slightly increased patch density in the area 1 year later (October 2004, 1.40 patches m⁻²). Most recruited patches consisted of rooting vegetative fragments of 1–2 shoots. Seedling recruitment was observed in Summer 2004 at both sites. Episodic, seedling recruitment comprised 30% and 25% of total patch recruitment in Es Port Bay and S’Estanyol, respectively. Patch survival increased with patch size and no direct removal was observed among patches of 5 shoots or more. Most patches grew along the study, shifting patch distribution towards larger sizes. Within the size range studied (1–150 shoots), absolute shoot recruitment (shoots year⁻¹) increased linearly with patch size (R² = 0.64, p < 4 × 10⁻⁵, N = 125), while specific shoot recruitment was constant (about 0.25 ± 0.05 year⁻¹), although its variance was large for small patches. Given the slow growth rate and the high survival of patches with 5 or more shoots, even the low patch recruitment rates reported here could play a significant role in the colonisation process of P. oceanica.     

Galactose-limited fed-batch cultivation of Escherichia coli for the production of lacto-N-tetraose

Lacto-N-tetraose (Gal(β1-3)GlcNAc(β1-3)Gal(β1-4)Glc) is one of the most abundant oligosaccharide structures in human milk. We recently described the synthesis of lacto-N-tetraose by a whole-cell biotransformation with recombinant Escherichia coli cells. However, only about 5% of the lactose was converted into lacto-N-tetraose by this approach. The major product obtained was the intermediate lacto-N-triose II (GlcNAc(β1-3)Gal(β1-4)Glc).In order to improve the bioconversion of lactose to lacto-N-tetraose, we have investigated the influence of the carbon source on the formation of lacto-N-tetraose and on the intracellular availability of the glycosyltransferase substrates, UDP-N-acetylglucosamine and UDP-galactose. By growth of the recombinant E. coli cells on D-galactose, the yield of lacto-N-tetraose (810.8 mg L⁻¹ culture) was 3.6-times higher compared to cultivation on D-glucose.Using fed-batch cultivation with galactose as sole energy and carbon source, a large-scale synthesis of lacto-N-tetraose was demonstrated. During the 26 h feeding phase the growth rate (μ = 0.05) was maintained by an exponential galactose feed. In total, 16 g L⁻¹ lactose were fed and resulted in final yields of 12.72 ± 0.21 g L⁻¹ lacto-N-tetraose and 13.70 ± 0.10 g L⁻¹ lacto-N-triose II. In total, 173 g of lacto-N-tetraose were produced with a space-time yield of 0.37 g L⁻¹ h⁻¹.