Vignette d'image

Guerin, Patrick

Nom
Guerin, Patrick
Affiliation principale
Site web
Fonction
Professeur associƩ
Email
patrick.guerin@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/310

RĆ©sultat de la recherche

Filtres

31
3
3
RĆ©initialiser les filtres

ParamĆØtres

Voici les ƩlƩments 1 - 3 sur 3
  • Publication
    AccĆØs libre
    (1S,3S,7R)-3-methyl-Ī±-himachalene from the male sandfly Lutzomyia longipalpis (Diptera: Psychodidae) induces neurophysiological responses and attracts both males and females
    (2005)
    Spiegel, C.N.
    ;
    Jeanbourquin, Philippe 
    ;
    Guerin, Patrick 
    ;
    Hooper, A.M.
    ;
    Claude, S.
    ;
    Tabacchi, Raffaele 
    ;
    Sano, S.
    ;
    Mori, K.
    Lutzomyia longipalpis adult males form leks on or near hosts and release (1S,3S,7R)-3-methyl-Ī±-himachalene from their tergal glands to lure females to the same site for mating and feeding. Here we have examined whether the male-produced attractant could also serve as a male aggregation stimulus. High resolution chiral capillary gas chromatography analysis of male tergal gland extracts, synthetic (1S,3S,7R)-3-methyl-Ī±-himachalene, and a synthetic mixture of all isomers of 3-methyl-Ī±-himachalene, was coupled to electrophysiological recordings from ascoid sensillum receptor cells in antennae of male and female sandflies. Receptor cells of both sexes responded only to the main component of the male tergal gland extract that eluted at the same retention time as (1S,3S,7R)-3-methyl-Ī±-himachalene. Furthermore, of the eight 3-methyl-Ī±-himachalene isomers in the synthetic mixture only the fraction containing (1S,3S,7R)-3-methyl-Ī±-himachalene, co-eluting with an isomer of (1S*,3S*,7S*)-3-methyl-Ī±-himachalene, elicited an electrophysiological response from male and female ascoid sensillum receptor cells. Both males and females flew upwind in a wind tunnel towards a filter paper disk treated with either 4ā€“6 male equivalents of the tergal gland extract, pure (1S,3S,7R)-3-methyl-Ī±-himachalene or the synthetic mixture of eight isomers. This indicates that (1S,3S,7R)-3-methyl-Ī±-himachalene derived from L. longipalpis males may have a dual function in causing male aggregation as well as serving as a sex pheromone for females.
  • Publication
    AccĆØs libre
    Ultrastructure and receptor cell responses of the antennal grooved peg sensilla of Triatoma infestans (Hemiptera: Reduviidae)
    (2003)
    Diehl, Peter-Allan 
    ;
    Vlimant, MichĆØle 
    ;
    Guerenstein, Pablo
    ;
    Guerin, Patrick 
    Ultrastructural examination of grooved-peg (GP) sensilla on the antenna of fifth instar Triatoma infestans nymphs by scanning electron microscopy and transmission electron microscopy reveal that they are 8ā€“18 Ī¼m long with a diameter of about 2ā€“2.8 Ī¼m at the non-articulated base. Some pegs have a terminal pore. These double-walled wall-pore (dw-wp) sensilla have an outer cuticular wall with 13ā€“18 longitudinal grooves at the distal part of the peg. Groove channels are present at the bottom of the grooves from which radial spoke channels lead into the inner sensillum-lymph cavity. A dendrite sheath connects the tip of the thecogen cell to the inner cuticular wall thus forming separated outer and inner sensillum-lymph cavities. Four or five bipolar receptor cells are ensheathed successively within the GP sensilla by the thecogen cell, trichogen and tormogen cells. The inner dendritic segments of each sensory cell give rise at the ciliary constriction to an unbranched outer dendritic segment which can reach the tip of the sensillum.

    Electrophysiological recordings from the GP sensilla indicate that they house NH3, short-chain carboxylic acid and short-chain aliphatic amine receptor cells and can be divided into three functional sub-types (GP 1ā€“3). All GP sensilla carry a receptor cell excited by aliphatic amines, such as isobutylamine, a compound associated with vertebrate odour. GP type 1 and 2 sensilla house, in addition, an NH3-excited cell whereas the type 2 sensilla also contains a short-chain carboxylic acid receptor. No cell particularly sensitive to either NH3 or carboxylic acids was found in the grooved-peg type 3 sensilla. GP types 1, 2 and 3 represent ca. 36, 10 and 43% of the GP sensilla, respectively, whereas the remaining 11% contain receptor cells that manifest normal spontaneous activity but do not respond to any of the afore mentioned stimuli.
  • Publication
    AccĆØs libre
    Ammonia attracts the haematophagous bug Triatoma infestans : behavioural and neurophysiological data on nymphs
    (Springer, 1997)
    Taneja, J.
    ;
    Guerin, Patrick 
    1) Nymphs of the haematophagous bug Triatoma infestans (Heteroptera: Reduviidae) are attracted to volatiles from their own faeces on a servosphere. 2) Biological substrates attractive to triatomines release NH3: wetted triatomine faecal papers release NH3 at 256 ppb NH3 from a 60-g source and stale rabbit urine at 394 ppb from 200 ml. Ammonia released from aqueous NH3 also attracts bugs at doses of 3 ppb and 17 ppb on the servosphere. 3) Bugs typically show negative anemotaxis in a stimulus-free air-stream on the servosphere. At onset of stimulation with ammonia from either biological substrates or aqueous NH3 the bugs stop, move their antennae, turn and walk upwind, i.e. odour-mediated anemotaxis. 4) At lower NH3 doses a latency in attraction is recorded, but this latency disappears when the relative humidity of the stimulus delivery air-stream is dropped from 90 to 35%. 5) Electrophysiological recordings from single olfactory sensilla on antennae of Triatoma nymphs reveal two different types of NH3-excited receptors, both within grooved-peg sensilla. The responses of one of these receptor cells to NH3 has been studied in detail and shows that the action potential discharge rate is dose-dependent over the range 2ā€“200 ppb. 6) The amplitudes of electroantennograms recorded from Triatoma nymphs to NH3 are dose dependent over the range 5ā€“550 ppb.