| 55451. |
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| 55452. |
- Ragnarsson Stabo, Henrik, et al.
(författare)
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Can multi-frequency acoustics improve the monitoring of large zooplankton in large temperate lakes?
- 2014
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Ingår i: Aquatic Ecosystem Health and Management. - : Michigan State University Press. - 1463-4988 .- 1539-4077. ; 17, s. 374-381
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Tidskriftsartikel (refereegranskat)abstract
- Large zooplankton has an important role for the functioning of the ecosystem in many lakes. Most are predatory, which makes them both competitors as well as food for many planktivorous fish species. In general, it has been elusive to measure the abundance of this group of zooplankton with traditional sampling methods, particularly in large volumes of water. In this study we tested the potential and adequacy of multi-frequency hydroacoustics as a method to map the spatial patterns in abundance of the large zooplankton in Lake Vanern, Lake Vattern and Lake Malaren. In addition, we used a plankton net to groundtruth biovolume estimates vertically, and a Tucker trawl for the horizontal distribution. Two frequencies were used to separate the acoustic backscattering from fish, mysids and plankton. The main target species were Leptodora kindtii, Bythotrephes longimanus and Limnocalanus macrurus.The plankton communities were very heterogeneous both within and among the lakes. Lake Vanern and Lake Malaren were dominated by Leptodora, whereas Lake Vattern was dominated by Limnocalanus. Bottom depth at the sample site was the most important community structuring factor.Our results indicate that the biomass of large predatory zooplankton is comparably high and in most surveyed areas even higher than the biomass of planktivorous fish. Consequently, they are more important for the dynamics of lake food webs than previously assumed. Using multi-frequency hydroacoustics show promising results and with some alterations to the sampling design this would be a valuable addition to the traditional zooplankton monitoring in large lakes.
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| 55453. |
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| 55454. |
- Ragnarsson Stabo, Henrik, et al.
(författare)
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Kvantifiering av stora djurplankton i de stora sjöarna
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Stora djurplankton (>2 mm) fyller en viktig funktion i många sjöekosystem. De flesta är rovdjur, vilket leder till att de är både konkurrenter och föda till många planktonätande fiskar. Dessa storväxta planktonarter kan också utgöra viktig föda för unga rovfiskar, t.ex. gös (Sander lucioperca). I denna studie testades olika metoder för att kartlägga och kvantifiera förekomsten av stora djurplankton i Vänern, Vättern och Mälaren. Det har visat sig att den traditionella provtagningen ofta missar de stora djurplantonarterna. Här testade vi en stor och grovmaskig planktonhåv för att få ett mått på biomassorna av plankton per ytenhet. Tuckertrål kombinerat med hydroakustik användes för att få ett mått på arternas vertikalfördelning och rumsliga fördelning. Flera frekvenser användes för att skilja på den detekterade energin från fisk och djurplankton som vid ekolodning reflekteras från organismerna. Totalt samlades 58 håv- och trålprover in. Planktonsamhället varierade starkt både mellan och inom sjöar. Vänern och Mälaren dominerades av Leptodora, medan Vättern dominerades av Limnocalanus. Djupet var avgörande för vilka arter som förekom i proverna, speciellt tydligt var det hos Limnocalanus som främst förekom i det kalla vattnet under språngskiktet. Hydroakustisk visade sig vara en möjlig metod för att mäta mängden stora djurplankton i de stora sjöarna. Mysider har tidigare visats ge starka och urskiljningsbara signaler i Vättern. Vår undersökning visade att även tofsmygglarver (Chaoborus) gav mycket starka signaler, som riskerar att överskugga de svagare signalerna från djurplankton. Vi föreslår därför att eventuell framtida hydroakustisk övervakning ska ske i dagsljus då både mysider och tofsmygglarver håller sig nära eller på botten. Våra resultat visar att biomassan stora djurplankton per ytenhet är i samma storleksordning som mängden fisk. Det indikerar att de är viktiga i födoväven och bör övervakas. Hydroakustik kombinerad med håvning eller Tucker-trålning skulle utgöra ett värdefullt komplement till den vanliga djurplanktonprovtagningen.
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| 55455. |
- Ragunathrao, Vijay Avin Balaji, et al.
(författare)
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Sphingosine-1-Phosphate Receptor 1 Activity Promotes Tumor Growth by Amplifying VEGF-VEGFR2 Angiogenic Signaling
- 2019
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Ingår i: Cell Reports. - : CELL PRESS. - 2211-1247. ; 29:11, s. 3472-3487
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Tidskriftsartikel (refereegranskat)abstract
- The vascular endothelial growth factor-A (VEGF-A)-VEGFR2 pathway drives tumor vascularization by activating proangiogenic signaling in endothelial cells (ECs). Here, we show that EC-sphingosine-1-phosphate receptor 1 (S1PR1) amplifies VEGFR2-mediated angiogenic signaling to enhance tumor growth. We show that cancer cells induce S1 PR1 activity in ECs, and thereby, conditional deletion of Si PR1 in ECs (EC-Slpr1(-/-) mice) impairs tumor vascularization and growth. Mechanistically, we show that S1 PR1 engages the heterotrimeric G-protein Gi, which amplifies VEGF-VEGFR2 signaling due to an increase in the activity of the tyrosine kinase c-Abl1. c-Abl1, by phosphorylating VEGFR2 at tyrosine-951, prolongs VEGFR2 retention on the plasmalemma to sustain Rac1 activity and EC migration. Thus, S1 PR1 or VEGFR2 antagonists, alone or in combination, reverse the tumor growth in control mice to the level seen in EC-Slpr1(-/-) mice. Our findings suggest that blocking S1 PR1 activity in ECs has the potential to suppress tumor growth by preventing amplification of VEGF-VEGFR2 signaling.
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| 55456. |
- Raguso, Robert A., et al.
(författare)
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Floral biology of North American Oenothera sect. Lavauxia (Onagraceae): Advertisements, rewards, and extreme variation in floral depth
- 2007
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Ingår i: Annals of the Missouri Botanical Garden. - 0026-6493. ; 94:1, s. 236-257
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Tidskriftsartikel (refereegranskat)abstract
- We studied the floral biology of five North American members of Oenothera L. sect. Lavauxia (Spach) Endl. (Onagraceae L.) in field and common greenhouse settings. Oenothera sect. Lavauxia floral morphology ranges from small, cleistogamous flowers (O. flava subsp. flava (A. Nels.) Garrett in Garrett) to sonic of the longest-tubed flowers in North America (O. flava subsp. taraxacoides (Wooton & Standl.) W. L. Wagner). Our goal was to compare qualitative and quantitative aspects of floral advertisement and reward among taxa in section Lavauxia. All taxa are night-blooming and self-compatible, have yellow petals with ultraviolet reflectance, and produce floral scents dominated by nitrogenous compounds and monoterpenes. Methyl nicotinate is present in the fragrances of all taxa of section Lavauxia regardless of flower size or putative mating system. Because this floral volatile is largely absent from other Oenothera species, we hypothesize that it is a synapomorphy for section Lavauxia. The rare O. acutissima W. L. Wagner, which is endemic to the Uintah Mountains, is polymorphic for odors dominated by linalool- or ocimene-derived compounds). Field observations in its type locality in northeastern Utah, U.S.A., revealed frequent floral visitation by crepuscular hawkmoths during the first 1.5 hours after anthesis, a pattern common to O. flava subsp. taraxacoides and other large-flowered Oenothera throughout western North America. Quantitative aspects of floral advertisement (flower size, scent emission) and reward (nectar volume) are dramatically reduced in putatively autogamous taxa (O. flava subsp. flava, O. triloba Nutt.). whereas qualitative aspects (flower color, scent, and nectar chemistry) remain comparable. All taxa could be distinguished through ordination of characters related to flower size, herkogamy. and scent chemistry. Extreme nectar tube length variation across the range of O. flava renders this an excellent model system for measuring the costs and mechanisms of shifts between outcrossing and autogamy.
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| 55457. |
- Raguz, Veronika, et al.
(författare)
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Plant uptake of elements in soil and pore water : Field observations versus model assumptions
- 2013
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Ingår i: Journal of Environmental Management. - : Elsevier BV. - 0301-4797 .- 1095-8630. ; 126, s. 147-156
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Tidskriftsartikel (refereegranskat)abstract
- Contaminant concentrations in various edible plant parts transfer hazardous substances from polluted areas to animals and humans. Thus, the accurate prediction of plant uptake of elements is of significant importance. The processes involved contain many interacting factors and are, as such, complex. In contrast, the most common way to currently quantify element transfer from soils into plants is relatively simple, using an empirical soil-to-plant transfer factor (TF). This practice is based on theoretical assumptions that have been previously shown to not generally be valid. Using field data on concentrations of 61 basic elements in spring barley, soil and pore water at four agricultural sites in mid-eastern Sweden, we quantify element-specific TFs. Our aim is to investigate to which extent observed element-specific uptake is consistent with TF model assumptions and to which extent TF's can be used to predict observed differences in concentrations between different plant parts (root, stem and ear). Results show that for most elements, plant-ear concentrations are not linearly related to bulk soil concentrations, which is congruent with previous studies. This behaviour violates a basic TF model assumption of linearity. However, substantially better linear correlations are found when weighted average element concentrations in whole plants are used for IF estimation. The highest number of linearly-behaving elements was found when relating average plant concentrations to soil pore-water concentrations. In contrast to other elements, essential elements (micronutrients and macronutrients) exhibited relatively small differences in concentration between different plant parts. Generally, the TF model was shown to work reasonably well for micronutrients, whereas it did not for macronutrients. The results also suggest that plant uptake of elements from sources other than the soil compartment (e.g. from air) may be non-negligible.
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| 55458. |
- Rahardjo, Harrina E., et al.
(författare)
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Expression and distribution of the transient receptor potential cationic channel ankyrin 1 (TRPA1) in the human seminal vesicles
- 2023
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Ingår i: Health Science Reports. - : WILEY. - 2398-8835. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- Background and AimsThe transient receptor potential cationic channel ankyrin 1 (TRPA1), a channel protein permeable to most divalent cations, has been suggested to play a role in mechano-afferent/efferent signaling (including the release of neurotransmitters) in the human urinary tract (bladder, prostate, and urethra). To date, only a few studies have addressed the expression of this receptor in male and female reproductive tissues. The present study aimed to evaluate human seminal vesicles (SVs) for the expression and localization of TRPA1. MethodsSV tissue was obtained from 5 males who had undergone pelvic surgery due to malignancies of the prostate or urinary bladder. The expression of messenger ribonucleic acid (mRNA) specifically encoding for the TRPA1 protein was elucidated by means of reverse transcriptase polymerase chain reaction (RT-PCR). Using immunohistochemical methods, the distribution of TRPA1 was examined in relation to the endothelial and neuronal nitric oxide synthases (eNOS, nNOS) and the neuropeptides calcitonin gene-related peptide (CGRP) and vasoactive intestinal polypeptide (VIP). ResultsRT-PCR revealed signals related to the expected molecular size of 656 bp. Immunohistochemistry demonstrated that TRPA1 is located in nerves running through the smooth muscle portion of the SV. Here, the protein is in part co-localized with nNOS and CGRP, whereas no co-localization with VIP was registered. Dot-like signals specific for TRPA1 were observed in the cytoplasm of epithelial cells lining the lumen of glandular spaces. The epithelial layer also presented staining for eNOS. The smooth musculature appeared free of immunosignals for TRPA1. ConclusionThe results convincingly show the expression of TRPA1 in nerve endings as well as in epithelial cells of the SV. Based on its location in epithelial cells, TRPA1 might be involved in the mechanism of the NO/cyclic guanosine monophosphate (GMP)-mediated signaling and also the control of secretory function (mediated by cyclic GMP) in the human SV.
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| 55459. |
- Rahimi, Shadi, 1982, et al.
(författare)
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Co-culturing Bacillus subtilis and wastewater microbial community in a bio-electrochemical system enhances denitrification and butyrate formation
- 2020
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Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947. ; 397
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Tidskriftsartikel (refereegranskat)abstract
- Bio-augmentation could be a promising strategy to improve processes for treatment and resource recovery from wastewater. In this study, the Gram-positive bacterium Bacillus subtilis was co-cultured with the microbial communities present in wastewater samples with high concentrations of nitrate or ammonium. Glucose supplementation (1%) was used to boost biomass growth in all wastewater samples. In anaerobic conditions, the indigenous microbial community bio-augmented with B. subtilis was able to rapidly remove nitrate from wastewater. In these conditions, B. subtilis overexpressed nitrogen assimilatory and respiratory genes including nasD, nasE, narG, narH, and narI, which arguably accounted for the observed boost in denitrification. Next, we attempted to use the ammonium- and nitrate-enriched wastewater samples bio-augmented with B. subtilis in the cathodic compartment of bioelectrochemical systems (BES) operated in anaerobic condition. B. subtilis only had low relative abundance in the microbial community, but bio-augmentation promoted the growth of Clostridium butyricum and C. beijerinckii, which became the dominant species. Both bio-augmentation with B. subtilis and electrical current from the cathode in the BES promoted butyrate production during fermentation of glucose. A concentration of 3.4 g/L butyrate was reached with a combination of cathodic current and bio-augmentation in ammonium-enriched wastewater. With nitrate-enriched wastewater, the BES effectively removed nitrate reaching 3.2 mg/L after 48 h. In addition, 3.9 g/L butyrate was produced. We propose that bio-augmentation of wastewater with B. subtilis in combination with bioelectrochemical processes could both boost denitrification in nitrate-containing wastewater and enable commercial production of butyrate from carbohydrate- containing wastewater, e.g. dairy industry discharges. These results suggest that B. subtilis bio-augmentation in our BES promotes simultaneous wastewater treatment and butyrate production. © 2020 The Authors
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| 55460. |
- Rahimi, Shadi, 1982, et al.
(författare)
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Ginsenoside Rg3 Reduces the Toxicity of Graphene Oxide Used for pH-Responsive Delivery of Doxorubicin to Liver and Breast Cancer Cells
- 2023
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Ingår i: Pharmaceutics. - : MDPI AG. - 1999-4923. ; 15:2
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Tidskriftsartikel (refereegranskat)abstract
- Doxorubicin (DOX) is extensively used in chemotherapy, but it has serious side effects and is inefficient against some cancers, e.g., hepatocarcinoma. To ameliorate the delivery of DOX and reduce its side effects, we designed a pH-responsive delivery system based on graphene oxide (GO) that is capable of a targeted drug release in the acidic tumor microenvironment. GO itself disrupted glutathione biosynthesis and induced reactive oxygen species (ROS) accumulation in human cells. It induced IL17-directed JAK-STAT signaling and VEGF gene expression, leading to increased cell proliferation as an unwanted effect. To counter this, GO was conjugated with the antioxidant, ginsenoside Rg3, prior to loading with DOX. The conjugation of Rg3 to GO significantly reduced the toxicity of the GO carrier by abolishing ROS production. Furthermore, treatment of cells with GO–Rg3 did not induce IL17-directed JAK-STAT signaling and VEGF gene expression—nor cell proliferation—suggesting GO–Rg3 as a promising drug carrier. The anticancer activity of GO–Rg3–DOX conjugates was investigated against Huh7 hepatocarcinoma and MDA-MB-231 breast cancer cells. GO–Rg3–DOX conjugates significantly reduced cancer cell viability, primarily via downregulation of transcription regulatory genes and upregulation of apoptosis genes. GO–Rg3 is an effective, biocompatible, and pH responsive DOX carrier with potential to improve chemotherapy—at least against liver and breast cancers.
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