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  1. Book ; Online ; E-Book: Monitoring environmental contaminants

    Johnson, Steven

    (Environmental contaminants)

    2021  

    Author's details editor, Steven Johnson
    Series title Environmental contaminants
    Keywords Environmental monitoring
    Subject code 363.7063
    Language English
    Size 1 online resource (viii, 141 pages) :, illustrations
    Publisher Elsevier
    Publishing place Amsterdam
    Document type Book ; Online ; E-Book
    Remark Zugriff für angemeldete ZB MED-Nutzerinnen und -Nutzer
    ISBN 0-444-64336-2 ; 0-444-64335-4 ; 978-0-444-64336-0 ; 978-0-444-64335-3
    Database ZB MED Catalogue: Medicine, Health, Nutrition, Environment, Agriculture

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  2. Article ; Online: Steven D. Johnson.

    Johnson, Steven D

    Current biology : CB

    2023  Volume 33, Issue 15, Page(s) R788–R789

    Abstract: Interview with Steve Johnson, who works on plant-pollinator interactions at the University of KwaZulu-Natal in South Africa. ...

    Abstract Interview with Steve Johnson, who works on plant-pollinator interactions at the University of KwaZulu-Natal in South Africa.
    MeSH term(s) South Africa ; Plants ; Pollination
    Language English
    Publishing date 2023-08-08
    Publishing country England
    Document type Interview
    ZDB-ID 1071731-6
    ISSN 1879-0445 ; 0960-9822
    ISSN (online) 1879-0445
    ISSN 0960-9822
    DOI 10.1016/j.cub.2023.07.002
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Pollination of Chamaepentas nobilis (Rubiaceae) by long‐proboscid hawkmoths in south‐central Africa: Trait mismatching and floral scent chemistry

    Johnson, Steven D.

    Biotropica. 2024 Jan., v. 56, no. 1 p.162-169

    2024  

    Abstract: The evolution of extremely long (>10 cm) floral tubes in angiosperms is closely linked with adaptation for pollination by long‐proboscid hawkmoths. In most cases, pollen is placed on the head or body of these moths, selecting for floral tubes that match ... ...

    Abstract The evolution of extremely long (>10 cm) floral tubes in angiosperms is closely linked with adaptation for pollination by long‐proboscid hawkmoths. In most cases, pollen is placed on the head or body of these moths, selecting for floral tubes that match or slightly exceed their proboscis length as this ensures contact with reproductive parts of the flower. However, in the case of Chamaepentas nobilis (Rubiaceae), anthers are inserted inside the c. 12‐cm floral tubes and coat the proboscis of visiting hawkmoths with sticky pollen, meaning that insects with proboscides longer than the floral tube can be effective pollinators, despite trait mismatching. Direct observations and camera trapping on granite outcrops in central Zambia showed that C. nobilis was visited both by Agrius convolvuli (proboscis length c. 13 cm) and Xanthopan morganii (proboscis length c. 17 cm), which are the only moth species in Africa that can access the small amounts of dilute nectar at the base of the floral tube. Pollen on the proboscides of captured hawkmoths was confirmed to originate from C. nobilis. Key floral advertising traits of C. nobilis include early evening anthesis, the highly reflective white limbus, and the evening production of scent dominated by oxygenated aromatic and terpenoid compounds known to elicit antennal responses of A. convolvuli. This study shows that that A. convolvuli and X. morganii share floral resources and jointly pollinate C. nobilis, despite their proboscides differing in length and being mismatched with the corolla tube length.
    Keywords Agrius convolvuli ; Rubiaceae ; cameras ; chemistry ; corolla ; evolution ; flowering ; granite ; moths ; nectar ; odors ; pollen ; pollination ; proboscis ; terpenoids ; Zambia
    Language English
    Dates of publication 2024-01
    Size p. 162-169.
    Publishing place John Wiley & Sons, Ltd
    Document type Article ; Online
    Note JOURNAL ARTICLE
    ZDB-ID 2052061-X
    ISSN 1744-7429 ; 0006-3606
    ISSN (online) 1744-7429
    ISSN 0006-3606
    DOI 10.1111/btp.13293
    Database NAL-Catalogue (AGRICOLA)

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  4. Article ; Online: Spiers Memorial Lecture: From optical to THz control of materials.

    Johnson, Steven L

    Faraday discussions

    2022  Volume 237, Page(s) 9–26

    Abstract: Advances over the past decade have presented new avenues to achieve control over material properties using intense pulses of electromagnetic radiation, with frequencies ranging from optical (approximately 1 PHz, or ... ...

    Abstract Advances over the past decade have presented new avenues to achieve control over material properties using intense pulses of electromagnetic radiation, with frequencies ranging from optical (approximately 1 PHz, or 10
    Language English
    Publishing date 2022-09-15
    Publishing country England
    Document type Journal Article
    ISSN 1364-5498
    ISSN (online) 1364-5498
    DOI 10.1039/d2fd00098a
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Bird pollination.

    Johnson, Steven D

    Current biology : CB

    2022  Volume 32, Issue 20, Page(s) R1059–R1060

    Abstract: Johnson gives an overview of bird pollinators and the plant species they pollinate. ...

    Abstract Johnson gives an overview of bird pollinators and the plant species they pollinate.
    MeSH term(s) Animals ; Pollination ; Flowers ; Birds ; Plants
    Language English
    Publishing date 2022-10-19
    Publishing country England
    Document type Journal Article
    ZDB-ID 1071731-6
    ISSN 1879-0445 ; 0960-9822
    ISSN (online) 1879-0445
    ISSN 0960-9822
    DOI 10.1016/j.cub.2022.06.081
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

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  6. Article ; Online: Vaccination and Immunoprotection in People with HIV.

    Johnson, Steven C

    Topics in antiviral medicine

    2021  Volume 28, Issue 3, Page(s) 465–468

    Abstract: Vaccines play an important role in HIV primary care and are available for several sexually transmitted infections, including those caused by hepatitis A virus (HAV), hepatitis B virus (HBV), and human papillomavirus (HPV). HAV vaccination is increasingly ...

    Abstract Vaccines play an important role in HIV primary care and are available for several sexually transmitted infections, including those caused by hepatitis A virus (HAV), hepatitis B virus (HBV), and human papillomavirus (HPV). HAV vaccination is increasingly important, given recent hepatitis A outbreaks and lack of immunity in many adults. A novel formulation of the hepatitis B vaccine shows promise in increasing rates of seroprotection. The Advisory Committee on Immunization Practices recommends the meningococcal conjugate vaccine for all individuals with HIV and has expanded the age range for administration of the HPV vaccine, recommending shared decision making about its administration in adults aged 27 to 45 years. This article summarizes a presentation by Steven C. Johnson, MD, at the International Antiviral Society-USA (IAS-USA) annual continuing education program held in New York, New York, in September 2019.
    MeSH term(s) Adult ; Advisory Committees ; HIV Infections/prevention & control ; HIV Infections/transmission ; Hepatitis A ; Hepatitis B Vaccines/administration & dosage ; Humans ; Meningococcal Vaccines/administration & dosage ; Middle Aged ; New York ; Papillomavirus Vaccines/administration & dosage ; Vaccination
    Chemical Substances Hepatitis B Vaccines ; Meningococcal Vaccines ; Papillomavirus Vaccines
    Language English
    Publishing date 2021-06-08
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2656632-1
    ISSN 2161-5853 ; 2161-5853
    ISSN (online) 2161-5853
    ISSN 2161-5853
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Investing in what matters most

    Johnson, Steven Mana'oakamai

    Science (New York, N.Y.)

    2022  Volume 376, Issue 6589, Page(s) 141

    Abstract: Faced with a family crisis, a marine scientist finds parallels with Earth's imperiled coral reefs. ...

    Abstract Faced with a family crisis, a marine scientist finds parallels with Earth's imperiled coral reefs.
    Language English
    Publishing date 2022-04-07
    Publishing country United States
    Document type Journal Article
    ZDB-ID 128410-1
    ISSN 1095-9203 ; 0036-8075
    ISSN (online) 1095-9203
    ISSN 0036-8075
    DOI 10.1126/science.abo5005
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

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  8. Article ; Online: Beyond pollen:ovule ratios: Evolutionary consequences of pollinator dependence and pollination efficiency for pollen and ovule production in angiosperms.

    Harder, Lawrence D / Johnson, Steven D

    American journal of botany

    2023  Volume 110, Issue 6, Page(s) e16177

    Abstract: Premise: The relative per-flower production of ovules and pollen varies broadly with angiosperm mating systems, with outcrossing types commonly producing more pollen grains per ovule than selfing types. The evolutionary causes of this variation are ... ...

    Abstract Premise: The relative per-flower production of ovules and pollen varies broadly with angiosperm mating systems, with outcrossing types commonly producing more pollen grains per ovule than selfing types. The evolutionary causes of this variation are contentious, especially the relevance of pollination risk. Resolution of this debate may have been hampered by its focus on pollen:ovule (P:O) ratios rather than on the evolution of pollen and ovule numbers per se.
    Methods: Using published mean ovule and pollen counts, we analyzed associations with the proportion of removed pollen that reaches stigmas (pollen-transfer efficiency) and differences between pollinator-dependent and autogamous forms within and among species. Analyses involved Bayesian methods that simultaneously considered variation in pollen and ovule numbers and accounted for phylogenetic relatedness. We also assessed the utility of P:O ratios as mating-system proxies and their association with female outcrossing rates.
    Results: Median pollen number declined consistently with pollen-transfer efficiency among species, whereas median ovule number did not. Similarly, in both intraspecific and interspecific analyses, pollinator-dependent plants produced more pollen than autogamous plants, whereas ovule production did not differ statistically. Distributions of P:O ratios overlapped extensively for self-incompatible and self-compatible species and for different mating-system classes, and P:O ratios correlated weakly with outcrossing rate.
    Conclusions: Our findings demonstrate that pollinator dependence and pollination efficiency commonly influence the evolution of pollen number per flower but have more limited effects on ovule number. P:O ratios provide ambiguous, possibly misleading, information about mating systems, especially when compared among clades.
    MeSH term(s) Pollination ; Phylogeny ; Ovule ; Magnoliopsida ; Bayes Theorem ; Reproduction ; Pollen ; Flowers
    Language English
    Publishing date 2023-06-05
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2935-x
    ISSN 1537-2197 ; 0002-9122
    ISSN (online) 1537-2197
    ISSN 0002-9122
    DOI 10.1002/ajb2.16177
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: The economy of pollen dispersal in flowering plants.

    Johnson, Steven D / Harder, Lawrence D

    Proceedings. Biological sciences

    2023  Volume 290, Issue 2008, Page(s) 20231148

    Abstract: Mating success of flowering plants depends strongly on the efficiencies of pollen removal from flowers and its subsequent dispersal to conspecific stigmas. We characterized the economy of pollen dispersal in flowering plants by analysing pollen fates and ...

    Abstract Mating success of flowering plants depends strongly on the efficiencies of pollen removal from flowers and its subsequent dispersal to conspecific stigmas. We characterized the economy of pollen dispersal in flowering plants by analysing pollen fates and their correlates for 228 species. The mean percentage of pollen removed from flowers (removal efficiency) varied almost twofold according to the type of pollen-dispersal unit, from less than 45% for orchids and milkweeds with solid pollinia, to greater than 80% for species with granular monads or sectile (segmented) pollinia. The mean percentage of removed pollen reaching stigmas (pollen transfer efficiency, PTE) varied from 2.4% for species with separate monads to 27.0% for orchids with solid pollinia. These values tended to be higher in plants with single pollinator species and in those with non-grooming pollinators. Nectar production increased removal efficiency, but did not influence PTE. Among types of pollen-dispersal units, the net percentage of produced pollen that was dispersed to stigmas varied negatively with removal efficiency and positively with PTE, indicating the relative importance of the latter for overall pollen economy. These findings confirm the key importance of floral traits, particularly pollen packaging, for pollen dispersal outcomes and highlight the under-appreciated pollination efficiency of non-grooming pollinators.
    MeSH term(s) Magnoliopsida ; Pollen ; Reproduction ; Pollination ; Plants ; Flowers
    Language English
    Publishing date 2023-10-04
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 209242-6
    ISSN 1471-2954 ; 0080-4649 ; 0962-8452 ; 0950-1193
    ISSN (online) 1471-2954
    ISSN 0080-4649 ; 0962-8452 ; 0950-1193
    DOI 10.1098/rspb.2023.1148
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    Zs.A 1364: Show issues Location:
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  10. Article ; Online: Rodent responses to volatile compounds provide insights into the function of floral scent in mammal-pollinated plants.

    Johnson, Steven D / Govender, Keeveshnee

    Philosophical transactions of the Royal Society of London. Series B, Biological sciences

    2022  Volume 377, Issue 1853, Page(s) 20210167

    Abstract: Flowers pollinated by mammals have evolved in many plant families. Several scent compounds that attract bats to flowers have been identified, but the chemical ecology of pollination mutualisms between plants and ground-dwelling mammals is poorly ... ...

    Abstract Flowers pollinated by mammals have evolved in many plant families. Several scent compounds that attract bats to flowers have been identified, but the chemical ecology of pollination mutualisms between plants and ground-dwelling mammals is poorly understood. Rodents are key pollinators in South Africa and rely heavily on olfaction to locate food. Our aim was to identify compounds that may function to attract rodents to flowers. Eighteen volatile compounds, including 14 that are prominent in the scent of rodent-pollinated flowers, were used in choice experiments involving wild-caught individuals of four native rodent species. Rodents were generally attracted to oxygenated aliphatic compounds, specifically ketones and esters, but not to some aromatic compounds common in floral scents of insect-pollinated species, nor to a sulfide compound that is attractive to bats. Associative conditioning using sugar solution as a reward had only weak effects on the attractiveness of compounds to rodents. The attractive effect of some compounds disappeared when they were blended with compounds that did not attract rodents. We conclude that aliphatic ketones and esters are likely to play a key role in attracting rodents to flowers. Deployment of these compounds may allow plants to exploit rodent sensory bias that evolved in other contexts such as intra-specific communication and searching for seeds. This article is part of the theme issue 'Natural processes influencing pollinator health: from chemistry to landscapes'.
    MeSH term(s) Animals ; Esters ; Ketones ; Mammals ; Odorants ; Rodentia/physiology
    Chemical Substances Esters ; Ketones
    Language English
    Publishing date 2022-05-02
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 208382-6
    ISSN 1471-2970 ; 0080-4622 ; 0264-3839 ; 0962-8436
    ISSN (online) 1471-2970
    ISSN 0080-4622 ; 0264-3839 ; 0962-8436
    DOI 10.1098/rstb.2021.0167
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    Einzelsignatur: Show issues

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