Increases in benthic community production and metabolism in response to marine‐derived nutrients from spawning Atlantic salmon (Salmo salar)

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Feeding response of the cotton aphid,Aphis gossypii,to sublethal rates of flonicamid and imidacloprid

The cotton aphid, Aphis gossypii Glover (Hemiptera: Aphididae), is an important sap‐sucking pest of many plants, including melons and peppers. This study was conducted to determine the effects of sublethal exposure to flonicamid and imidacloprid and the mechanisms by which these insecticides affect the feeding behavior of A. gossypii. The median lethal concentrations (LC₅₀) of flonicamid and imidacloprid for adult A. gossypii were 2.40 and 1.92 mg l^?1, respectively. The lower lethal concentrations of flonicamid were 1.01 mg l^?1 (LC₃₀) and 0.29 mg l^?1 (LC₁₀), and those of imidacloprid were 0.82 mg l^?1 (LC₃₀) and 0.24 mg l^?1 (LC₁₀). The developmental period of A. gossypii nymphs at LC₃₀ was 3.6 days for both insecticides, which was shorter than that of the untreated controls (4.2 days). Longevity and total fecundity of A. gossypii adults were decreased at the sublethal concentrations of both insecticides. The lowest net reproductive rate was observed in A. gossypii treated with the LC₃₀ of flonicamid. Feeding behavior analyses using an electrical penetration graph showed that sublethal concentrations of flonicamid and imidacloprid had significant effects on the duration of phloem ingestion. Higher doses of flonicamid induced starvation by inhibiting phloem ingestion, whereas imidacloprid acted as a contact toxin rather than an inhibitor of feeding behavior.     

Properties of the vastus lateralis muscle in relation to age and physiological function in master cyclists aged 55–79 years

In this study, results are reported from the analyses of vastus lateralis muscle biopsy samples obtained from a subset (n = 90) of 125 previously phenotyped, highly active male and female cyclists aged 55–79 years in regard to age. We then subsequently attempted to uncover associations between the findings in muscle and in vivo physiological functions. Muscle fibre type and composition (ATPase histochemistry), size (morphometry), capillary density (immunohistochemistry) and mitochondrial protein content (Western blot) in relation to age were determined in the biopsy specimens. Aside from an age‐related change in capillary density in males (r = ?.299; p = .02), no other parameter measured in the muscle samples showed an association with age. However, in males type I fibres and capillarity (p < .05) were significantly associated with training volume, maximal oxygen uptake, oxygen uptake kinetics and ventilatory threshold. In females, the only association observed was between capillarity and training volume (p < .05). In males, both type II fibre proportion and area (p < .05) were associated with peak power during sprint cycling and with maximal rate of torque development during a maximal voluntary isometric contraction. Mitochondrial protein content was not associated with any cardiorespiratory parameter in either males or females (p > .05). We conclude in this highly active cohort, selected to mitigate most of the effects of inactivity, that there is little evidence of age‐related changes in the properties of VL muscle across the age range studied. By contrast, some of these muscle characteristics were correlated with in vivo physiological indices.     

Contrasting effects of low‐level phosphorus and nitrogen enrichment on growth of the mat‐forming alga Didymosphenia geminata in an oligotrophic river

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Microalgae for phosphorus removal and biomass production: a six species screen for dual‐purpose organisms

Microalgae biofuel production can be feasible when a second function is added, such as wastewater treatment. Microalgae differ in uptake of phosphorus (P) and growth, making top performer identification fundamental. The objective of this screen was to identify dual‐purpose candidates capable of high rates of P removal and growth. Three freshwater – Chlorella sp., Monoraphidium minutum sp., and Scenedesmus sp. – and three marine – Nannochloropsis sp., N. limnetica sp., and Tetraselmis suecica sp. – species were batch cultured in 250 mL flasks over 16 days to quantitate total phosphorus (TP) removal and growth as a function of P loads (control, and 5, 10, and 15 mg L^?1 enrichment of control). Experimental design used 100 μmol m^?2 s^?1 of light, a light/dark cycle of 14/10 h, and no CO₂ enrichment. Phosphorus uptake was dependent on species, duration of exposure, and treatment, with significant interaction effects. Growth was dependant on species and treatment. Not all species showed increased P removal with increasing P addition, and no species demonstrated higher growth. Nannochloropsis sp and N. limnetica sp. performed poorly across all treatments. Two dual‐purpose candidates were identified. At the 10 mg L^?1 treatment Monoraphidium minutum sp. removed 67.1% (6.66 mg L^?1 ± 0.60 SE) of TP at day 8, 79.3% (7.86 mg L^?1 ± 0.28 SE) at day 16, and biomass accumulation of 0.63 g L^?1 ± 0.06 SE at day 16. At the same treatment Tetraselmis suecica sp. removed 79.4% (6.98 mg L^?1 ± 0.24 SE) TP at day 8, 83.0% (7.30 mg L^?1 ± 0.60 SE) at day 16, and biomass of 0.55 g L^?1 ± 0.02 SE at day 16. These species merit further study using high‐density wastewater cultures and lipid profiling to assess suitability for a nutrient removal and biomass/biofuel production scheme.     

The end effector of circadian heart rate variation: the sinoatrial node pacemaker cell

Cardiovascular function is regulated by the rhythmicity of circadian, infradian and ultradian clocks. Specific time scales of different cell types drive their functions: circadian gene regulation at hours scale, activation-inactivation cycles of ion channels at millisecond scales, the heart''s beating rate at hundreds of millisecond scales, and low frequency autonomic signaling at cycles of tens of seconds. Heart rate and rhythm are modulated by a hierarchical clock system: autonomic signaling from the brain releases neurotransmitters from the vagus and sympathetic nerves to the heart’s pacemaker cells and activate receptors on the cell. These receptors activating ultradian clock functions embedded within pacemaker cells include sarcoplasmic reticulum rhythmic spontaneous Ca²⁺ cycling, rhythmic ion channel current activation and inactivation, and rhythmic oscillatory mitochondria ATP production. Here we summarize the evidence that intrinsic pacemaker cell mechanisms are the end effector of the hierarchical brain-heart circadian clock system. [BMB Reports 2015; 48(12): 677-684]     

Intra‐thallus differentiation of fatty acid and pigment profiles in some temperate Fucales and Laminariales

Intra‐thallus variation in fatty acid and pigment contents and profiles was investigated in five species of Laminariales (Alaria esculenta, Laminaria digitata, Laminaria hyperborea, Saccharina latissima, and Saccorhiza polyschides), and three Fucales (Ascophyllum nodosum, Fucus serratus, and Himanthalia elongata). Significant variation occurred across all species and compounds examined. Total fatty acids were generally higher in the fronds, with highest levels and largest variability observed in A. nodosum (1.5% of dry weight (DW) in the base, 6.3% of DW in frond tips). Percentages of the omega‐3 fatty acids 18:4 n‐3 and 20:5 n‐3 were generally higher in more distal parts, while 20:4 n‐6 exhibited a contrasting pattern, with higher levels in basal structures and holdfasts. Trends for pigments were similar to those for fatty acids in Laminariales. In the Fucales, highest levels were detected in the mid‐fronds, with lower concentrations in meristematic areas. Highest levels and greatest variability in pigments (e.g., chl a) was observed in F. serratus (1.07 mg · g^?1 DW in the base, 3.04 mg · g^?1 DW in the mid frond). Intra‐thallus variability was attributed to physiological functions of the respective thallus sections, e.g., photosynthetic activity, meristematic tissue, and to variations in physical attributes of the structures investigated. Regarding potential commercial nutritional applications, fronds appeared to represent most suitable source materials, due to higher levels of pigments, polyunsaturated fatty acids, and more preferable omega‐3/omega‐6 ratios.     

Ion flux and cortisol responses of cardinal tetra,Paracheirodon axelrodi (Schultz, 1956), to additives (tetracycline,tetracycline + salt or Amquel®) used during transportation: contributions to Amazonian ornamental fish trade

The cardinal tetra, Paracheirodon axelrodi (Schultz), is the most important ornamental fish exported from Brazil and Colombia. During the transport of this species, Amazon fishermen usually add unmeasured amounts of tetracycline and/or table salt to the water in an effort to mitigate stress and mortality. The aim of the present study was to analyze the effect of salt, the antibiotic tetracycline and the ammonia chelating agent Amquel^® in the transport of this species. Cardinal tetras were submitted to a 24‐h boat transport in water containing either tetracycline hydrochloride (2.5 mg L^?1), Amquel^® (26.41 mg L^?1), tetracycline + table salt (2.5 mg L^?1 + 66.67 mg L^?1), or additive‐free water (control treatment). Whole‐body cortisol measurements showed that fish transported with any water additive had lower cortisol levels compared to control. However, based on ionoregulatory and water quality parameters, the addition of tetracycline, Amquel^® or the combination tetracycline + salt to the water of transport of cardinal tetras is not recommended when compared to control. Although Amquel^® helped stabilize the pH and diminish total ammonia levels in the transport water, this compound dramatically increased net Na⁺ and Cl^? uptake, and therefore compromised cardinal tetra ionoregulation.     

Effects of varying levels of dietary vitamin E (α‐tocopherol) on growth performance,proximate and fatty acid composition of juvenile silver pomfret (Pampus argenteus Euphrasen, 1788)

This study investigated the effects of elevated dietary levels of vitamin E (α‐tocopherol) on growth performance, proximate composition and fatty acid profiles of juvenile silver pomfret, Pampus argenteus. Three semi‐purified experimental diets were formulated to contain 49% protein and 16% lipid. High docosahexaenoic acid (DHA) tuna oil was added to the diets to supplement DHA. A graded level of vitamin E (0‐, 50‐, and 100 mg kg^?1) was added to experimental diets 1 to 3, respectively. Analyzed vit. E levels were 155.2, 195.3 and 236.4 mg kg^?1 in diets 1, 2 and 3, respectively. The experiment was conducted for 12 weeks with juvenile silver pomfret (29.6 ± 7.6 g) using a flow‐through system consisting of nine 1‐m³ tanks. Each treatment had three replicates and fish were stocked at the rate of 20 m^?3. Growth performance and feed utilization parameters of fish fed diets 2 and 3 were significantly (P < 0.05) higher than in fish fed diet 1, but the parameters in diets 2 and 3 did not differ significantly (P > 0.05). Although whole body protein levels were not influenced by the dietary vit. E levels, whole body lipid in fish fed diet 2 was significantly higher than in fish fed the other diets. The whole body vit. E levels in fish fed diet 2 (22.6 mg kg^?1) and diet 3 (24.1 mg kg^?1) were significantly (P < 0.05) higher than in those fed diet 1 (18.2 mg kg^?1). Whole body total saturated fatty acids were significantly lower, and DHA levels higher in fish fed diets 2 and 3 than those fed diet 1. The results of the present study suggest that increasing dietary supplementation of vit. E in high lipid diets enhances the growth performance of fish and that a dietary level of 196 mg kg^?1 vit. E is suitable for the growth of silver pomfret.     

The impact of Arabidopsis thaliana SNF1‐related‐kinase 1 (SnRK1)‐activating kinase 1 (SnAK1) and SnAK2 on SnRK1 phosphorylation status: characterization of a SnAK double mutant

Arabidopsis thaliana SNF1‐related‐kinase 1 (SnRK1)‐activating kinase 1 (AtSnAK1) and AtSnAK2 have been shown to phosphorylate in vitro and activate the energy signalling integrator, SnRK1. To clarify this signalling cascade in planta, a genetic‐ and molecular‐based approach was developed. Homozygous single AtSnAK1 and AtSnAK2 T‐DNA insertional mutants did not display an apparent phenotype. Crossing of the single mutants did not allow the isolation of double‐mutant plants, whereas self‐pollinating the S1?/? S2+/? sesquimutant specifically gave approximatively 22% individuals in their offspring that, when rescued on sugar‐supplemented media in vitro, were shown to be AtSnAK1 AtSnAK2 double mutants. Interestingly, this was not obtained in the case of the other sesquimutant, S1+/? S2?/?. Although reduced in size, the double mutant had the capacity to produce flowers, but not seeds. Immunological characterization established the T‐loop of the SnRK1 catalytic subunit to be non‐phosphorylated in the absence of both SnAKs. When the double mutant was complemented with a DNA construct containing an AtSnAK2 open reading frame driven by its own promoter, a normal phenotype was restored. Therefore, wild‐type plant growth and development is dependent on the presence of SnAK in vivo, and this is correlated with SnRK1 phosphorylation. These data show that both SnAKs are kinases phosphorylating SnRK1, and thereby they contribute to energy signalling in planta.     

Reference values for selected hematological and serum biochemical parameters of Senegalese sole (Solea senegalensis Kaup, 1858) juveniles under intensive aquaculture conditions

This work aims to establish normal reference intervals for selected hemato‐biochemical parameters, based on their potential clinical relevance, and which may contribute to evaluating the health, nutritional and welfare status of Senegalese sole (Solea senegalensis Kaup, 1858) juveniles. Thirty‐one healthy Senegalese sole juveniles grown under intensive aquaculture conditions were used in the study. Based on the robust method with Box–Cox transformation data the established reference intervals for hematological parameters were: hematocrit 12–26%, hemoglobin 2.8–6 g dl^?1, erythrocytes 90–97.0% total, leucocytes 4–10% total; erythrocyte indices and differential leucocytes counts were also evaluated. Reference intervals for biochemical parameters were (g dl^?1) glucose 19–86 mg dl^?1, total protein 2.6–6.3, albumin 1–2.34, globulins 1.8–4.1, lipids 0.7–1.3, triglycerides 0.3–1.8, total cholesterol 0.1–0.9 g dl^?1, HDL‐cholesterol 4–65 mg dl^?1, LDL‐cholesterol 7–532 mg dl^?1, sodium 124–202 mmol L^?1), potassium 1.1–4.6 mmol L^?1, calcium 7.6–13.2 mg L^?1, magnesium 1.8–4.8 mg L^?1, inorganic phosphorus 3.4–9.5 mg L^?1, alkaline phosphatase 93–598 U L^?1, aspartate aminotransferase 118–605 U L^?1, lactate dehydrogenase 8.7–782 U L^?1, and creatine phosphokinase 31.5–552 U L^?1. This data is expected to provide a valuable tool to monitor the stress, health and nutritional conditions of Senegalese sole juveniles under aquaculture production.     

Assessing nitrate leaching during the three‐first years of Miscanthus × giganteus from on‐farm measurements and modeling

Miscanthus × giganteus is often regarded as one of the most promising crops to produce sustainable bioenergy. This perennial crop, renowned for its high productivity associated with low input requirements, in particular regarding fertilizers, is thought to have low environmental impacts, but few data are available to confirm this. Our study aimed at assessing nitrate leaching from Miscanthus × giganteus crops in farmers' fields, thus including a wide range of soil and cropping system conditions. We focused on the first years of growth after planting as experimental studies have suggested that Miscanthus × giganteus, once established, results in low nitrate leaching. We combined on‐farm measurements and modeling to estimate drainage, leached nitrogen, and nitrate concentration in drainage water in 38 fields located in Center‐East France during two winters (November 2010 to March 2011, November 2011 to March 2012). Nitrate leaching and nitrate concentration in drainage water were on average very low. Nitrate leaching averaged 6 kg N ha^?1 whereas nitrate concentration averaged 12 mg l^?1. These low values are attributable to the low estimates of drainage water (mean = 166 mm) but also to the low soil mineral nitrogen contents measured at the beginning of winter (mean = 37 kg N ha^?1). Our results were, however, very variable, mainly due to the crop age: nitrate leaching and nitrate concentration were critically higher during the winter following the first growth year of Miscanthus × giganteus, reflecting the low development of the crop. This variability was also explained by the range of soil and cropping conditions explored in the on‐farm design: shallow and/or sandy soils as well as fields where establishment failed had a higher risk of nitrate leaching.     

Different fermentation strategies by Schizochytrium mangrovei strain pq6 to produce feedstock for exploitation of squalene and omega‐3 fatty acids

Schizochytrium mangrovei strain PQ 6 was investigated for coproduction of docosahexaenoic acid (C22: 6ω‐3, DHA ) and squalene using a 30‐L bioreactor with a working volume of 15 L under various batch and fed‐batch fermentation process regimes. The fed‐batch process was a more efficient cultivation strategy for achieving higher biomass production rich in DHA and squalene. The final biomass, total lipid, unsaponifiable lipid content, and DHA productivity were 105.25 g · L^?1, 43.40% of dry cell weight, 8.58% total lipid, and 61.66 mg · g^?1 · L^?1, respectively, after a 96 h fed‐batch fermentation. The squalene content was highest at 48 h after feeding glucose (98.07 mg · g^?1 of lipid). Differences in lipid accumulation during fermentation were correlated with changes in ultrastructure using transmission electron microscopy and Nile Red staining of cells. The results may be of relevance to industrial‐scale coproduction of DHA and squalene in heterotrophic marine microalgae such as Schizochytrium .     

Influences of salinity on the physiology and distribution of the Arctic coralline algae,Lithothamnion glaciale (Corallinales,Rhodophyta)

In Greenland, free‐living red coralline algae contribute to and dominate marine habitats along the coastline. Lithothamnion glaciale dominates coralline algae beds in many regions of the Arctic, but never in Godthåbsfjord, Greenland, where Clathromorphum sp. is dominant. To investigate environmental impacts on coralline algae distribution, calcification and primary productivity were measured in situ during summers of 2015 and 2016, and annual patterns of productivity in L. glaciale were monitored in laboratory‐based mesocosm experiments where temperature and salinity were manipulated to mimic high glacial melt. The results of field and cold‐room measurements indicate that both L. glaciale and Clathromorphum sp. had low calcification and photosynthetic rates during the Greenland summer (2015 and 2016), with maximum of 1.225 ± 0.17 or 0.002 ± 0.023 μmol CaCO ₃ · g^?1 · h^?1 and ?0.007 ±0.003 or ?0.004 ± 0.001 mg O₂ · L^?1 · h^?1 in each species respectively. Mesocosm experiments indicate L. glaciale is a seasonal responder; photosynthetic and calcification rates increase with annual light cycles. Furthermore, metabolic processes in L. glaciale were negatively influenced by low salinity; positive growth rates only occurred in marine treatments where individuals accumulated an average of 1.85 ± 1.73 mg · d^?1 of biomass through summer. These results indicate high freshwater input to the Godthåbsfjord region may drive the low abundance of L . glaciale , and could decrease species distribution as climate change increases freshwater input to the Arctic marine system via enhanced ice sheet runoff and glacier calving.     

Understanding the stoichiometric limitation of herbivore growth: the importance of feeding and assimilation flexibilities

Ecological stoichiometry suggests that herbivore growth is limited by phosphorus when this element in the diet is < 8.6 μg P mg C^?1 (C : P atomic ratio > 300). However, in nature, it is not necessarily related to the relative phosphorus content in diets. This may be the result of complex feeding and assimilation responses to diets. We examined these possibilities using herbivorous plankton fed mono‐specific and mixed algae varying in phosphorus content of 1.6 to 8.1 μg P mg C^?1. The herbivores showed a 10‐fold growth rate difference among the diets. Growth rates related poorly with phosphorus content in the diets (r² = 0.07), better with P ingestion rate (r² = 0.41) and best with phosphorus assimilation rate (r² = 0.69). Inclusion of assimilation rates for carbon and fatty acids increased 7% of the explained growth variance. These results indicate that the feeding and assimilation flexibilities play pivotal roles in acquiring a deficient element and in regulating growth rate.     

Effects of metalaxyl enantiomers stress on root activity and leaf antioxidant enzyme activities in tobacco seedlings

The objective of this experiment was to study the effects of metalaxyl enantiomers on the activity of roots and antioxidative enzymes in tobacco seedlings. Water culture experiment was conducted to analyze the effects of different concentrations of metalaxyl enantiomers (30 and 10 mg L^?1) on root activity and leaf superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities and malondialdehyde (MDA) content of tobacco seedlings. The results showed that metalaxyl significantly inhibited root activity and significantly improved leaf SOD, POD, and CAT activities and MDA content. A better physiological response in tobacco seedlings was observed at 30 mg L^?1 than at 10 mg L^?1 metalaxyl. The stereoselectivity for different enantiomers had no obvious effect on root activity and the leaf POD activity, but it affected significantly the SOD and CAT activities and MDA content. The SOD activity was promoted more by R‐enantiomer than by S‐enantiomer at 30 mg L^?1 metalaxyl, and the same effect was observed on CAT activity from the beginning to the end of the stress period. The MDA content under the stress by R‐enantiomer was higher than that under the stress by S‐enantiomer at 10 mg L^?1 metalaxyl.     

Plant maintenance and environmental stress. Summarising the effects of contrasting elevation,soil, and latitude on Quercus ilex respiration rates

Aims

Rice (Oryza sativa L.), wheat (Triticum aestivum L.) and common bean (Phaseolus vulgaris L.) are major staple food crops consumed worldwide. Zinc (Zn) deficiency represents a common micronutrient deficiency in human populations, especially in regions of the world where staple food crops are the main source of daily calorie intake. Foliar application of Zn fertilizer has been shown to be effective for enriching food crop grains with Zn to desirable amounts for human nutrition. For promoting adoption of this practice by growers, it is important to know whether foliar Zn fertilizers can be applied along with pesticides to wheat, rice and also common bean grown across different soil and environmental conditions.

Methods

The feasibility of foliar application of zinc sulphate (ZnSO₄.7H₂O) to wheat, rice and common bean in combination with commonly used five fungicides and nine insecticides was investigated under field conditions at the 31 sites-years of seven countries, i.e., China, India, Pakistan, Thailand, Turkey, Brazil and Zambia.

Results

Significant increases in grain yields were observed with foliar Zn/foliar Zn?+?pesticide (5.2–7.7 % of wheat and 1.6–4.2 % of rice) over yields with no Zn treatment. In wheat, as average of all experiments, higher grain Zn concentrations were recorded with foliar Zn alone (41.2 mg kg^?1) and foliar Zn?+?pesticide (38.4 mg kg^?1) as compared to no Zn treatment (28.0 mg kg^?1). Though the magnitude of grain Zn enrichment was lesser in rice than wheat, grain Zn concentrations in brown rice were significantly higher with foliar Zn (24.1 mg kg^?1) and foliar Zn?+?pesticide (23.6 mg kg^?1) than with no Zn (19.1 mg kg^?1). In case of common bean, grain Zn concentration increased from 68 to 78 mg kg^?1 with foliar Zn alone and to 77 mg kg^?1 with foliar Zn applied in combination with pesticides. Thus, grain Zn enrichment with foliar Zn, without or with pesticides, was almost similar in all the tested crops.

Conclusions

The results obtained at the 31 experimental site-years of seven countries revealed that foliar Zn fertilization can be realized in combination with commonly-applied pesticides to contribute Zn biofortification of grains in wheat, rice and common bean. This agronomic approach represents a useful practice for the farmers to alleviate Zn deficiency problem in human populations.

     

Regime shift in the littoral ecosystem of volcanic Lake Atitlán in Central America: combined role of stochastic event and invasive plant species

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Effects of elevated nitrate concentration on early thyroid morphology in Atlantic salmon (Salmo salar Linnaeus, 1758)

A study was conducted to determine if exposure to elevated nitrate (NO₃^‐)(3.76 ± 0.07 and 93.15 ± 2.79) during embryonic development influences the morphology of thyroid tissue in newly hatched Atlantic salmon, Salmo salar. Digital three‐dimensional imaging of thyroid follicles in S. salar showed that the thyroid tissue in newly hatched alevin consisted mainly of spherical follicles dispersed throughout the lower jaw in close proximity to the ventral aorta and other blood vessels. With these digital models, the number of follicles, average volume per follicle, and total luminal volume were calculated for alevin exposed to well water or 93.15 mg L^?1 NO₃‐N during embryogenesis. There were no statistically significant differences in any of these parameters, suggesting that the normal thyroid development of S. salar could be relatively insensitive to excess environmental NO₃^‐. These results are promising for the culture of Atlantic salmon embryos in recirculating aquaculture systems that naturally accumulate NO₃^‐ as a product of nitrification.