Biodiesel synthesis from Chlorella vulgaris under effect of nitrogen limitation,intensity and quality light: estimation on the based fatty acids profiles

Cultures under nitrogen limitation for Chlorella vulgaris were kept under different light quality (white, blue, yellow and violet) at 70 and 140 µE m^?2 s^?1; to evaluate the effect on fatty acids profiles and biodiesel quality. The results showed a maximum biomass and cell density at 140 µE m^?2 s^?1 of: white light (0.69 g L^?1 and 6.5?×?10⁶ cells mL^?1, respectively) and blue light (0.65 g L^?1 and 8.0?×?10⁶ cells mL^?1, respectively); compared to violet and yellow light. The chlorophyll concentration (µg mg^?1 biomass dry weight) at 70 µE m^?2 s^?1 were in the order of light: white (25.61)?>?violet (17.10)?>?yellow (11.68)?>?blue (11.40) and, at 140 µE m^?2 s^?1 were: violet (23.64)?>?white (10.20)?>?yellow (9.66)?>?blue (7.99), suggesting the violet light stimulates the increase of chlorophyll a at higher intensity. The maximum lipid content (% w/w) were present under blue light (43.11), yellow (70.92) and violet (83.87) at 140 µE m^?2 s^?1. The different wavelengths did not have a negative effect on the quality of the biodiesel, however; violet light presented greater productivity and the indicators such as CFPP were related to the oxidative stability value and low PUFA content, leading biodiesel to good oxidative stability.

     

Acclimation of photosynthetic capacity to irradiance in tree canopies in relation to leaf nitrogen concentration and leaf mass per unit area

The observation of acclimation in leaf photosynthetic capacity to differences in growth irradiance has been widely used as support for a hypothesis that enables a simplification of some soil‐vegetation‐atmosphere transfer (SVAT) photosynthesis models. The acclimation hypothesis requires that relative leaf nitrogen concentration declines with relative irradiance from the top of a canopy to the bottom, in 1 : 1 proportion. In combination with a light transmission model it enables a simple estimate of the vertical profile in leaf nitrogen concentration (which is assumed to determine maximum carboxylation capacity), and in combination with estimates of the fraction of absorbed radiation it also leads to simple ‘big‐leaf’ analytical solutions for canopy photosynthesis. We tested how forests deviate from this condition in five tree canopies, including four broadleaf stands, and one needle‐leaf stand: a mixed‐species tropical rain forest, oak (Quercus petraea (Matt.) Liebl), birch (Betula pendula Roth), beech (Fagus sylvatica L.) and Sitka spruce (Picea sitchensis (Bong.) Carr). Each canopy was studied when fully developed (mid‐to‐late summer for temperate stands). Irradiance (Q, µmol m^?2 s^?1) was measured for 20 d using quantum sensors placed throughout the vertical canopy profile. Measurements were made to obtain parameters from leaves adjacent to the radiation sensors: maximum carboxylation and electron transfer capacity (V_a, J_a, µmol m^?2 s^?1), day respiration (R_da, µmol m^?2 s^?1), leaf nitrogen concentration (N_m, mg g^?1) and leaf mass per unit area (L_a, g m^?2). Relative to upper‐canopy values, V_a declined linearly in 1 : 1 proportion with N_a. Relative V_a also declined linearly with relative Q, but with a significant intercept at zero irradiance (P < 0·01). This intercept was strongly related to L_a of the lowest leaves in each canopy (P < 0·01, r² = 0·98, n= 5). For each canopy, daily lnQ was also linearly related with lnV_a(P < 0·05), and the intercept was correlated with the value for photosynthetic capacity per unit nitrogen (PUN: V_a/N_a, µmol g^?1 s^?1) of the lowest leaves in each canopy (P < 0·05). V_a was linearly related with L_a and N_a(P < 0·01), but the slope of the V_a : N_a relationship varied widely among sites. Hence, whilst there was a unique V_a : N_a ratio in each stand, acclimation in V_a to Q varied predictably with L_a of the lowest leaves in each canopy. The specific leaf area, L_m(cm² g^?1), of the canopy‐bottom foliage was also found to predict carboxylation capacity (expressed on a mass basis; V_m, µmol g^?1 s^?1) at all sites (P < 0·01). These results invalidate the hypothesis of full acclimation to irradiance, but suggest that L_a and L_m of the most light‐limited leaves in a canopy are widely applicable indicators of the distribution of photosynthetic capacity with height in forests.     

Blood Vessel Density in De Novo Formed Adipose Tissue Is Decreased Upon Overexpression of TIMP‐1

Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) play a role in the development of obesity by contributing to adipogenesis, angiogenesis, and extracellular matrix degradation. We have evaluated a potential functional role of TIMP‐1, which inhibits most MMPs, in in vivo adipogenesis. Therefore, human (h) TIMP‐1 was overexpressed by injection in the tail vein of NUDE mice of an adenoviral vector 3 days before injection of 3T3‐F442A preadipocytes in the back. After 4 weeks of high‐fat diet, the de novo formed fat was analyzed. Overexpression of hTIMP‐1 had no effect on de novo formed fat pad mass. However, the blood vessel density of the fat pads from mice overexpressing hTIMP‐1 was significantly lower than in controls (587 ± 11 mm^?2 vs. 806 ± 20 mm^?2, P < 0.0001) whereas the adipocytes were somewhat larger (1,477 ± 44 µm² vs. 1,285 ± 32 µm², P = 0.03). Thus, in vivo hTIMP‐1 overexpression did not significantly affect the extent of de novo adipose tissue formation, but was associated with significantly lower blood vessel density.     

Combined gas exchange characteristics,chlorophyll fluorescence and response curves as selection traits for temperature tolerance in maize genotypes

Maize is a low-temperature (LT)-sensitive plant and its physiological responses towards LT of temperate regions developed is an adaptive trait. To further our understanding about the response of maize to LT at the physiological and photosynthesis level, we conducted Infrared Gas Analysis (IRGA using LICOR6400-XT in 45-day-old grown two maize genotypes, one from temperate region (Gurez-Kashmir Himalayas), viz., Gurez local (Gz local), and another from tropics (Gujarat), viz., GM6. This study was carried out to evaluate the underlying physiological mechanisms in the two differentially temperature-tolerant maize genotypes. Net photosynthetic rate (A/P_N), 18.253 in Gz local and 25.587 (µmol CO₂ m^?2 s^?1) in GM6; leaf conductance (gs), 0.0102 in Gz local and 0.0566 (mmol H₂O m^?2 s^?1) in GM6; transpiration rate (E), 0.5371 in Gz local and 2.9409 (mmol H₂O m^?2 s^?1) in GM6; and water use efficiency (WUE), 33.9852 in Gz local and 8.7224 (µmol CO₂ mmol H₂O^?1) in GM6, were recorded under ambient conditions. Also, photochemical efficiency of photosystem II (PSII) (F_v/F_m), 0.675 in Gz local and 0.705 in GM6; maximum photochemical efficiency (F_v′/F_m′), 0.310234 in Gz local and 0.401391 in GM6; photochemical quenching (qP), 0.2375 in Gz local and 0.2609 in GM6; non-photochemical quenching (NPQ), 2.0036 in Gz local and 1.1686 in GM6; effective yield of PSII (ФPSII), 0.0789 in Gz local and 0.099 in GM6; and electron transport rate (ETR), 55.3152 in Gz local and 68.112 in GM6, were also evaluated in addition to various response curves, like light intensities and temperature. We observed that light response curves show the saturation light intensity requirement of 1600 µmol for both the genotypes, whereas temperature response curves showed the optimum temperature requirement for Gz local as 20 °C and for GM6 it was found to be 35 °C. The results obtained for each individual parameter and other correlational studies indicate that IRGA forms a promising route for quick and reliable screening of various stress-tolerant valuable genotypes, forming the first study of its kind.

     

Enhancement of phenylpropanoid enzymes and lignin in Phalaenopsis orchid and their influence on plant acclimatisation at different levels of photosynthetic photon flux

Effects of three levels of photosynthetic photon flux (PPF: 60, 160 and 300 μmol m⁻²s⁻¹) were investigated in one-month-old Phalaenopsis plantlets acclimatised ex vitro. Optimal growth, chlorophyll and carotenoid concentations, and a high carotenoid:chlorophyll a ratio were obtained at 160 μmol m⁻²s⁻¹, while net CO₂ assimilation (A), stomatal conductance (g), transpiration rate (E) and leaf temperature peaked at 300 μmol m⁻²s⁻¹, indicating the ability of the plants to grow ex vitro. Adverse effects of the highest PPF were reflected in loss of chlorophyll, biomass, non-protein thiol and cysteine, but increased proline. After acclimatisation, glucose-6-phosphate dehydrogenase, shikimate dehydrogenase, phenylalanine ammonia-lyase (PAL) and cinnamyl alcohol dehydrogenase (CAD) increased, as did lignin. Peroxidases (POD), which play an important role in lignin synthesis, were induced in acclimatised plants. Polyphenol oxidase (PPO) and β-glucosidase (β-GS) activities increased to a maximum in acclimatised plants at 300 μmol m⁻²s⁻¹. A positive correlation between PAL, CAD activity and lignin concentration was observed, especially at 160 and 300 μmol m⁻²s⁻¹. The study concludes that enhancement of lignin biosynthesis probably not only adds rigidity to plant cell walls but also induces defence against radiation stress. A PPF of 160 μmol m⁻²s⁻¹was suitable for acclimatisation when plants were transferred from in vitro conditions.     

Toxic effects of chlorpyrifos on the growth,hematology, and different organs histopathology of Nile tilapia,Oreochromis niloticus

Chlorpyrifos is a widely applied insecticide that permeates on most waterways and affects aquatic organisms. The growth performances, hematological and histological impacts on Nile tilapia, Oreochromis niloticus following a 60 day of exposure to varying concentrations of chlorpyrifos 20 EC (T₁ 08 µgL^?1, T₂ 16 µgL^?1, and T₃ 32 µgL^?1) were compared to a control T_c 0 µgL^?1. The 96-hour LC50 of chlorpyrifos 20 EC was calculated as 46.80 μgL^?1. The water quality parameters were recorded regularly. The value of dissolved O₂ and NH₃ stayed rather steady, although temperature varied considerably. It was revealed that as chlorpyrifos levels go up, the percentage of weight gain (WG %), specific growth rates (SGR), and survival rate decreases. The control group T_c had the highest percentages of SGR weight (1.16 ± 0.58) and the T₃ group had the lowest percentages of SGR weight (0.25 ± 0.77). The hematological assessment showed significant differences of hemoglobin concentration, white blood cell counts and red blood cell numbers between chlorpyrifos treatment and control group (P < 0.05). Histological alterations in the liver, gills, and muscle tissues reported to be worse for T₃ as compared to others. There were no statistical differences in GSI, HSI values between control and treatment groups. The chlorpyrifos 20 EC was shown to be highly toxic to O. niloticus at sub-lethal dosages.     

The Interactive Effect of Selenium and Farmyard Manure on Soil Microbial Activities,Yield and Selenium Accumulation by Wheat (Triticum aestivum L.) Grains

This study assessed the interactive effect of selenium (Se) and farmyard manure (FYM) on soil microbial activities, growth, yield, and Se accumulation by wheat grains. Preliminarily, the effect of Se (0–250 µg kg^?1 soil) and FYM (0–12.5 g kg^?1 soil) was assessed on soil microflora. Selenium exhibited an adverse impact on soil microflora; respiration was decreased at?≥?10 µg kg^?1 soil while dehydrogenase and urease activities were decreased at?≥?125 µg kg^?1 soil. At 250 µg Se kg^?1 soil, respiration, dehydrogenase and urease activities were decreased by 81, 40 and 35%, respectively, on unamended soil, and by 9, 47 and 22%, respectively, on FYM-amended soil. The subsequent plant experiments were conducted with same Se and FYM rates; one was harvested 42 days after sowing and other at crop maturity. The application of 125 µg Se kg^?1 and 12.5 g FYM kg^?1 soil improved seedling biomass by 12.6 and 22%, respectively, while their combined use lacked synergistic effect. Similarly, at maturity Se and FYM increased grain yield while their combined effect was not synergistic. The Se-induced suppression in microbial activities was not related to yield which was improved (11% at the highest rate in unamended soil) by Se application. Selenium application increased grain Se content in a rate-dependent manner, it increased from 0 to 1025 µg kg^?1 by applying 250 µg Se kg^?1 soil. Moreover, FYM application decreased Se accumulation in grains. It is concluded that FYM application increased soil microbial activities and yield but reduced grain Se accumulation in wheat on Se-applied soil.

     

Nanoparticles combined with cefixime as an effective synergistic strategy against Salmonella enterica typhi

Enteric fever caused by Salmonella typhi has been the most crucial health issue in rural people, especially in Southeast Asia and Africa. Another disease, Salmonellosis, caused by a large group of bacteria of the genus Salmonella, cause substantial economic loss resulting from mortality and morbidity. Higher concentration and repeated use of antibiotics to treat these diseases will likely develop antibiotic resistance among the microbes. The nanoparticle has good penetration power and can kill microbes. Combining two strategies by using nanoparticles with antibiotics kills microbes and reduces the chances of the development of antibiotics resistance. Silver, Nickel, Copper, and Zinc oxide Nanoparticles were chemically synthesized and characterized in this study. Silver nanoparticles at a concentration of 10 µg/ml inhibit all the strains under study.In comparison, silver nanoparticles (16.90 µg/ml), Nickel nanoparticles (83 µg ml^?1), Copper nanoparticles (249 µg ml^?1), and Zinc oxide (1614 µg ml^?1) along with 50 µg/ml cefixime gave maximum zone of inhibition of 35 mm, 19 mm, 31 mm and 23 mm respectively. The antimicrobial assay showed that silver nanoparticles presented good antibacterial performance against all multi-drug-resistant pathogenic Salmonella sp alone as well as in combinations. The present study proved that silver nanoparticles at the lowest concentration along with cefixime could be a possible alternative to control the multi-drug-resistant pathogens.     

Strain-related differences in bacterivory and demography of Diaphanosoma mongolianum (Cladocera) in relation to diet and previous exposure to cyanobacteria in nature

We compared the demographic variables and bacterivory of two strains of Diaphanosoma mongolianum from two water bodies in Spain, one without Microcystis (Maidevera in Zaragoza) and the other with dense Microcystis (La Albufera of Valencia). We hypothesized that the strain rarely exposed to Microcystis would be unable to grow on this cyanobacterial diet. We fed both strains Monoraphidium caribeum and Microcystis aeruginosa, together and separately, and compared their demographic variables. Monoraphidium caribeum was cultured in the laboratory on a defined medium, while the cyanobacteria were collected from La Albufera and sonicated before feeding the cladocerans (at 0.5?×?10⁶ cells ml^?1). We also tested the growth of D. mongolianum on bacterial diets by using seston (0–15 µm), bacterioplankton (0–3 µm) and mixed fractions (3–15 µm), from sieving Lake Albufera. We conducted population growth and life table demography experiments at 25 °C, using the two strains of D. mongolianum. Both strains had r (population growth rate) ranging from 0.05 to 0.3 d^?1, on all diets. The r was higher (0.18 d^?1) on the 0–15 µm seston compared to the mixed fraction (0.12 d^?1) although D. mongolianum also grew well on bacterioplankton (0.16 d^?1) alone. The response of the strains collected from two different water bodies was different to the test diets. We found that both strains of D. mongolianum could effectively utilize Microcystis for survival and growth, regardless of previous exposure to the cyanobacteria. The tested cladocerans could also grow well on small sized food particles (0–3 µm and 0–15 µm). Our results explain why D. mongolianum is common in eutrophic water bodies

     

First description of the environmental niche of the epibenthic dinoflagellate species Coolia palmyrensis,C. malayensis,and C. tropicalis (Dinophyceae) from Eastern Australia

Environmental variables such as temperature, salinity, and irradiance are significant drivers of microalgal growth and distribution. Therefore, understanding how these variables influence fitness of potentially toxic microalgal species is particularly important. In this study, strains of the potentially harmful epibenthic dinoflagellate species Coolia palmyrensis, C. malayensis, and C. tropicalis were isolated from coastal shallow water habitats on the east coast of Australia and identified using the D1‐D3 region of the large subunit (LSU) ribosomal DNA (rDNA). To determine the environmental niche of each taxon, growth was measured across a gradient of temperature (15–30°C), salinity (20–38), and irradiance (10–200 μmol photons · m^?2 · s^?1). Specific growth rates of Coolia tropicalis were highest under warm temperatures (27°C), low salinities (ca. 23), and intermediate irradiance levels (150 μmol photons · m^?2 · s^?1), while C. malayensis showed the highest growth at moderate temperatures (24°C) and irradiance levels (150 μmol photons · m^?2 · s^?1) and growth rates were consistent across the range of salinity levels tested (20–38). Coolia palmyrensis had the highest growth rate of all species tested and favored moderate temperatures (24°C), oceanic salinity (35), and high irradiance (>200 μmol photons · m^?2 · s^?1). This is the first study to characterize the environmental niche of species from the benthic harmful algal bloom genus Coolia and provides important information to help define species distributions and inform risk management.     

Repellency and toxicity of a CO2-derived cedarwood oil on hard tick species (Ixodidae)

The repellency and toxicity of a CO₂-derived cedarwood oil (CWO) was evaluated against actively questing unfed nymphs of four species of hard ticks: Amblyomma americanum (L.), Dermacentor variabilis (Say), Ixodes scapularis Say, and Rhipicephalus sanguineus (Latreille). Using a vertical climb bioassay for repellency, nymphs of these species avoided a CWO-treated filter paper in proportional responses to treatment concentrations. At 60 min of exposure, I. scapularis nymphs were most sensitive with 50% repellency concentration (RC₅₀) of 19.8 µg cm^?2, compared with RC₅₀ of 30.8, 83.8 and 89.6 µg cm^?2 for R. sanguineus, D. variabilis and A. americanum, respectively. Bioassays determined the lethal concentration for 50% (LC₅₀) and 90% (LC₉₀) mortality of nymphs exposed to CWO in treated vials after 24- and 48-h exposure. After 24 h exposure, the LC₅₀ values were 1.25, 3.45 and 1.42 µg cm^?2 and LC₉₀ values were 2.39, 7.59 and 4.14 µg cm^?2 for D. variabilis, I. scapularis and R. sanguineus, respectively, but had minimal effect on A. americanum. After 48 h exposure, the LC₅₀ values were 4.14, 0.78, 0.79 and 0.52 µg cm^?2, and LC₉₀ values were 8.06, 1.48, 1.54 and 1.22 µg cm^?2 for A. americanum, D. variabilis, I. scapularis and R. sanguineus, respectively. The repellency of CWO on tick species decreased with time. The repellency and toxicity bioassays demonstrated concentration-dependent responses of tick nymphs to the oil, indicating the potential of the CO₂-derived cedarwood oil be developed as an eco-friendly repellent and/or acaricide.

     

Soil N and C trace gas fluxes and microbial soil N turnover in a sessile oak (Quercus petraea (Matt.) Liebl.) forest in Hungary

During two intensive field campaigns in summer and autumn 2004 nitrogen (N₂O, NO/NO₂) and carbon (CO₂, CH₄) trace gas exchange between soil and the atmosphere was measured in a sessile oak (Quercus petraea (Matt.) Liebl.) forest in Hungary. The climate can be described as continental temperate. Fluxes were measured with a fully automatic measuring system allowing for high temporal resolution. Mean N₂O emission rates were 1.5 μg N m⁻² h⁻¹ in summer and 3.4 μg N m⁻² h⁻¹ in autumn, respectively. Also mean NO emission rates were higher in autumn (8.4 μg N m⁻² h⁻¹) as compared to summer (6.0 μg N m⁻² h⁻¹). However, as NO₂ deposition rates continuously exceeded NO emission rates (−9.7 μg N m⁻² h⁻¹ in summer and −18.3 μg N m⁻² h⁻¹ in autumn), the forest soil always acted as a net NO _x sink. The mean value of CO₂ fluxes showed only little seasonal differences between summer (81.1 mg C m⁻² h⁻¹) and autumn (74.2 mg C m⁻² h⁻¹) measurements, likewise CH₄uptake (summer: −52.6 μg C m⁻² h⁻¹; autumn: −56.5 μg C m⁻² h⁻¹). In addition, the microbial soil processes net/gross N mineralization, net/gross nitrification and heterotrophic soil respiration as well as inorganic soil nitrogen concentrations and N₂O/CH₄ soil air concentrations in different soil depths were determined. The respiratory quotient (ΔCO_{2 resp} ΔO_{2 resp}⁻¹) for the uppermost mineral soil, which is needed for the calculation of gross nitrification via the Barometric Process Separation (BaPS) technique, was 0.8978 ± 0.008. The mean value of gross nitrification rates showed only little seasonal differences between summer (0.99 μg N kg⁻¹ SDW d⁻¹) and autumn measurements (0.89 μg N kg⁻¹ SDW d⁻¹). Gross rates of N mineralization were highest in the organic layer (20.1–137.9 μg N kg⁻¹ SDW d⁻¹) and significantly lower in the uppermost mineral layer (1.3–2.9 μg N kg⁻¹ SDW d⁻¹). Only for the organic layer seasonality in gross N mineralization rates could be demonstrated, with highest mean values in autumn, most likely caused by fresh litter decomposition. Gross mineralization rates of the organic layer were positively correlated with N₂O emissions and negatively correlated with CH₄ uptake, whereas soil CO₂ emissions were positively correlated with heterotrophic respiration in the uppermost mineral soil layer. The most important abiotic factor influencing C and N trace gas fluxes was soil moisture, while the influence of soil temperature on trace gas exchange rates was high only in autumn.     

Photosynthetic and biochemical characterization of in vitro-derived African violet (Saintpaulia ionantha H. Wendl) plants to ex vitro conditions

African violet (Saintpaulia ionantha H. Wendl) is one of the most easily and commonly tissue-cultured ornamental plants. Despite this, there are limited reports on photosynthetic capacity and its impact on the plant quality during acclimatization. Various growth, photosynthetic and biochemical parameters and activities of antioxidant enzymes and dehydrins of micropropagated plants were assessed under three light intensities (35, 70, and 100 µmol m^?2 s^?1 photosynthetic photon flux density – PPFD). Fresh and dry plant biomass, plant height, and leaf area were optimal with high irradiance (70–100 µmol m^?2 s^?1 PPFD). Chlorophyll and carotenoid contents and net photosynthesis were optimal in plants grown under 70 µmol m^?2 s^?1 PPFD. Stomatal resistance, malondialdehyde content, and F_v/F_m values were highest at low light irradiance (35 µmol m^?2 s^?1 PPFD). The activities of three antioxidant enzymes, superoxide dismutase, catalase, and glutathione peroxidase, increased as light irradiance increased, signaling that high light irradiance was an abiotic stress. The accumulation of 55, 33, and 25 kDa dehydrins was observed with all light treatments although the expression levels were highest at 35 µmol m^?2 s^?1 PPFD. Irradiance at 70 µmol m^?2 s^?1 PPFD was suitable for the acclimatization of African violet plants. Both low and high irradiance levels (35 and 100 µmol m^?2 s^?1 PPFD) induced the accumulation of antioxidants and dehydrins in plants which reveals enhanced stress levels and measures to counter it.     

Evaluation of photosynthetic electron flow using simultaneous measurements of gas exchange and chlorophyll fluorescence under photorespiratory conditions

Simultaneous measurements of leaf gas exchange and chlorophyll fluorescence for Koelreuteria paniculata Laxm. at 380 ± 5.6 and 600 ± 8.5 ??mol mol^?1 were conducted, and the photosynthetic electron flow via photosystem II (PSII) to photosynthesis, photorespiration, and other electron-consuming processes were calculated. The results showed that the photosynthetic electron flow associated with carboxylation (J _c), oxygenation (J _o), and other electron-consuming processes (J _r) were 72.7, 45.7, and 29.4 ??mol(e^?) m^?2 s^?1 at 380 ??mol mol^?1, respectively; and 86.1, 35.3, and 48.2 ??mol(e^?) m^?2 s^?1 at 600 ??mol mol^?1, respectively. Our results revealed that other aspects associated with electronconsuming processes, except for photosynthesis and respiration, were neither negligible nor constant under photorespiratory conditions. Using maximum net photosynthetic rate (P _max), day respiration (R), photorespiration rate (R _l), and maximum electron flow via PSII (J _max), the use efficiency of electrons via PSII at saturation irradiance to fix CO₂ was calculated. The calculated results showed that the use efficiency of electrons via PSII to fix CO₂ at 600 ??mo^l mol^?1 was almost as effective as that at 380 ??mol mol^?1, even though more electrons passed through PSII at 600 ??mol mol^?1 than at 380 ??mol mol^?1.     

Dust mediated transfer of phosphorus to alpine lake ecosystems of the Wind River Range,Wyoming, USA

Alpine lakes receive a large fraction of their nutrients from atmospheric sources and are consequently sensitive to variations in both the amount and chemistry of atmospheric deposition. In this study we explored the spatial changes in lake water chemistry and biology along a gradient of dust deposition in the Wind River Range, Wyoming. Regional differences were explored using the variation in bulk deposition, lake water, sediment, and bedrock geochemistry and catchment characteristics. Dust deposition rates in the Southwestern region averaged 3.34 g m^?2 year^?1, approximately three times higher than deposition rates in the Northwestern region (average 1.06 g m^?2 year^?1). Dust-P deposition rates ranged from 87 µg P m² day^?1 in the Northwestern region to 276 µg P m² day^?1 in the Southwestern region. Subalpine and alpine lakes in the Southwestern region had greater total phosphorus (TP) concentrations (5–13 µg L^?1) and greater sediment phosphorus (SP) concentrations (2–5 mg g^?1) than similar lakes elsewhere in the region (1–8 µg L^?1 TP, 0.5–2 mg g^?1 SP). Lake phosphorus concentrations were related to dissolved organic carbon (DOC) across vegetation gradients, but related to the percent of bare rock, catchment area to lake area, and catchment steepness across dust deposition gradients. Modern phytoplankton and zooplankton biomasses were two orders of magnitude greater in the Southwest than in the Northwest, and alpine lakes in the Southwest had a unique diatom species assemblage with relatively higher concentrations of Asterionella formosa, Pseudostaurosira pseudoconstruens, and Pseudostaurosira brevistriata. These results suggests that catchment controls on P export to lakes (i.e. DOC) are overridden in dominantly bare rock basins where poor soils cannot effectively retain dust deposited P.     

Treatment of high-strength wastewater in tropical vertical flow constructed wetlands planted with Typha angustifolia and Cyperus involucratus

The ability of vertical flow (VF) constructed wetland systems to treat high-strength (ca. 300 mg L^?1 of COD and ca. 300 mg L^?1 total-nitrogen) wastewater under tropical climatic conditions was studied during a 5-month period. Nine 0.8-m diameter experimental VF units (depth 0.6 m) were used: three units were planted with Typha angustifolia L., another three units were planted with Cyperus involucratus Rottb and three units were unplanted. Each set of units were operated at hydraulic loading rates (HLRs) of 20, 50 and 80 mm d^?1. Cyperus produced more shoots and biomass than the Typha, which was probably stressed because of lack of water. The high evapotranspirative water loss from the Cyperus systems resulted in higher effluent concentrations of COD and total-P, but the mass removal of COD did not differ significantly between planted and unplanted systems. Average mass removal rates of COD, TKN and total-P at a HLR of 80 mm d^?1 were 17.8, 15.4 and 0.69 g m^?2 d^?1. The first-order removal rate constants at a HLR of 80 mm d^?1 for COD, TKN and total-P were 49.8, 30.1 and 13.5 m year^?1, respectively, which is in the higher range of k-values reported in the literature. The oxygen transfer rates were ca. 80 g m^?2 d^?1 in the planted systems as opposed to ca. 60 g m^?2 d^?1 in the unplanted systems. The number of Nitrosomonas was two to three orders of magnitude higher in the planted systems compared to the unplanted systems. Planted systems thus had significantly higher removal rates of nitrogen and phosphorus, higher oxygen transfer rates, and higher quantities of ammonia-oxidizing bacteria. None of the systems did, however, fully nitrify the wastewater, even at low loading rates. The vertical filters did not provide sufficient contact time between the wastewater and the biofilm on the gravel medium of the filters probably because of the shallow bed depth (0.6 m) and the coarse texture of the gravel. It is concluded that vertical flow constructed wetland systems have a high capacity to treat high-strength wastewater in tropical climates. The gravel and sand matrix of the vertical filter must, however, be designed in a way so that the pulse-loaded wastewater can pass through the filter medium at a speed that will allow the water to drain before the next dose arrives whilst at the same time holding the water back long enough to allow sufficient contact with the biofilm on the filter medium.     

LED irradiance level affects growth and nutritional quality of Brassica microgreens

This study examines the effect of irradiance level produced by solid-state light-emitting diodes (LEDs) on the growth, nutritional quality and antioxidant properties of Brassicaceae family microgreens. Kohlrabi (Brassica oleracea var. gongylodes, ‘Delicacy Purple’) mustard (Brassica juncea L., ‘Red Lion’), red pak choi (Brassica rapa var. chinensis, ‘Rubi F₁’) and tatsoi (Brassica rapa var. rosularis) were grown using peat substrate in controlled-environment chambers until harvest time (10 days, 21/17°C, 16 h). A system of five lighting modules with 455, 638, 665 and 731 nm LEDs at a total photosynthetic photon flux densities (PPFD) of 545, 440, 330, 220 and 110 µmol m^?2s^?1 respectively were used. Insufficient levels of photosynthetically active photon flux (110 µmol m^?2 s^?1) suppressed normal growth and diminished the nutritional value of the Brassica microgreens studied. In general, the most suitable conditions for growth and nutritional quality of the microgreens was 330–440 µmol m^?2 s^?1 irradiation, which resulted in a larger leaf surface area, lower content of nitrates and higher total anthocyanins, total phenols and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free-radical scavenging capacity. High light levels (545 µmol m^?2 s^?1), which was expected to induce mild photostress, had no significant positive impact for most of investigated parameters.     

Effects of light,temperature and salinity on the growth rate of harmful marine diatoms,Chaetoceros convolutus and C. concavicornis that kill netpen salmon

Chaetoceros convolutus and C. concavicornis have been implicated in the death of salmon in netpens in the Pacific Northwest by damaging the salmon's gills. To better understand how environmental factors affect the distribution of these two species, the interacting effects of light, temperature and salinity on growth rate were examined by growing these species under a range of temperatures (4–18 °C), light (10–175 μmol photon m⁻² s⁻¹) and salinities (10–30‰). For C. convolutus, the growth rate showed a hyperbolic relationship with irradiance at 8, 14 and 18 °C and light saturation occurred at 9, 14 and 20 μmol photon m^t s⁻¹ respectively. At 4 °C for C. convolutus and 8 °C for C. concavicornis, cells grew at μ_max, even at the lowest irradiances tested (10 μmol photon m⁻² s⁻¹). For C. convolutus, the amount of light required to saturate growth rate increased with temperature in an approximately linear fashion. The Q₁₀ was 1.88, calculated by averaging over both species. C. concavicornis was the more euryhaline species growing at salinities as low as 17.5‰, while C. convolutus grew only at 25‰ and above.     

Rapid, reversible alterations in spinach thylakoid appression upon changes in light intensity

Changes in light quantity and quality cause structural changes within the thylakoid membrane; long‐term responses have been described for so‐called ‘sun’ and ‘shade’ leaves. Many leaves, however, experience changes in irradiance on a time scale of minutes due to self‐shading and sun flecks. In this study, mature, attached spinach leaves were grown at 300 µmol photons m^?2 s^?1 then rapidly switched to a different light treatment. The treatment irradiances were 10, 800 or 1500 µmol m^?2 s^?1 for 10 min, or 10 or 20 min of self‐shading (about 10 µmol m^?2 s^?1). Image analysis of transmission electron micrographs revealed that a 10 min switch to a lower light intensity increased grana size and number per chloroplast profile by 10–20%. Returning the leaves to 300 µmol m^?2 s^?1 for 10 min reversed the phenomenon. Chlorophyll fluorescence measurements of detached, intact leaves at 77 K were suggestive of a transition from state 2 to state 1 upon shading. Diurnal ultrastructural measurements of granal size and number did not reveal a significant net change in ultrastructure over the time scale of hours. It is concluded that spinach chloroplasts can alter the degree of thylakoid appression in response to irradiance changes on a time scale of minutes. These ultrastructural responses are caused by biochemical and biophysical adjustments within the thylakoid membrane that serve to maximize photosynthesis and minimize photo‐inhibition under rapidly fluctuating light environments.     

Isolation and reconstruction of cardiac mitochondria from SBEM images using a deep learning-based method

Mitochondrial morphological defects are a common feature of diseased cardiac myocytes. However, quantitative assessment of mitochondrial morphology is limited by the time-consuming manual segmentation of electron micrograph (EM) images. To advance understanding of the relation between morphological defects and dysfunction, an efficient morphological reconstruction method is desired to enable isolation and reconstruction of mitochondria from EM images. We propose a new method for isolating and reconstructing single mitochondria from serial block-face scanning EM (SBEM) images. CDeep3M, a cloud-based deep learning network for EM images, was used to segment mitochondrial interior volumes and boundaries. Post-processing was performed using both the predicted interior volume and exterior boundary to isolate and reconstruct individual mitochondria. Series of SBEM images from two separate cardiac myocytes were processed. The highest F1-score was 95% using 50 training datasets, greater than that for previously reported automated methods and comparable to manual segmentations. Accuracy of separation of individual mitochondria was 80% on a pixel basis. A total of 2315 mitochondria in the two series of SBEM images were evaluated with a mean volume of 0.78 µm³. The volume distribution was very broad and skewed; the most frequent mitochondria were 0.04–0.06 µm³, but mitochondria larger than 2.0 µm³ accounted for more than 10% of the total number. The average short-axis length was 0.47 µm. Primarily longitudinal mitochondria (0–30 degrees) were dominant (54%). This new automated segmentation and separation method can help quantitate mitochondrial morphology and improve understanding of myocyte structure–function relationships.