Identification and functional study of three
            nAChR
            regulators, ubiquilin‐1,
            PICK
            1, and
            CRELD
            2, in
            Locusta migratoria manilensis
            dorsal unpaired median neurons

AbstractConidial hydrophobins in fungal pathogens of plants1,2, insects3,4, and humans5,6 are required for fungal attachment and are associated with high virulence. They are believed to contribute to the pathogenesis of infection by preventing immune recognition5,6. Here, we refute this generalisation offering a more nuanced analysis. We show that MacHYD3, a hydrophobin located on the conidial surface of the specialist entomopathogenic fungus Metarhizium acridum, activates specifically the humoral and cellular immunity of its own host insect, Locusta migratoria manilensis (Meyen) but not that of other non-host insects. When topically applied to the cuticle, purified MacHYD3 improved the resistance of locusts to both specialist and generalist fungal pathogens but had no effect on the fungal resistance of other insects, including Spodoptera frugiperda and Galleria mellonella. Hydrophobins extracted from the generalist fungal pathogens M. anisopliae and Beauveria bassiana had no effect on the resistance of locusts to fungal infection. Thus, the host locust has evolved to recognize the conidial hydrophobin of its specialist fungal pathogen, whereas conidial hydrophobins from generalist fungi are able to evade recognition. Our results distinguish the immunogenic potential of conidial hydrophobins between specialist and generalist fungi.

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OCTOPAMINERGIC MODULATION OF THE FOREWING STRETCH RECEPTOR IN THE LOCUST LOCUSTA MIGRATORIA

Journal of Experimental Biology ◽

10.1242/jeb.149.1.255 ◽

1990 ◽

Vol 149 (1) ◽

pp. 255-279 ◽

Cited By ~ 3

Author(s):

JAN-MARINO RAMIREZ ◽

IAN ORCHARD

Keyword(s):

Intact Animal ◽

Locusta Migratoria ◽

Beat Frequency ◽

Motor Pattern ◽

Stretch Receptor ◽

Maximal Effect ◽

Naturally Occurring ◽

Entire Central Nervous System ◽

Dorsal Unpaired Median ◽

Stimulation Of

Modulatory actions of various biogenic amines and peptides on the locust forewing stretch receptor (SR) were examined. The response of the SR to sinusoidal wing movements was unaffected by physiological concentrations (5×10−8moll−1) of the peptides AKHI, AKHII, proctolin and FMRFamide. The biogenic amine octopamine, however, enhanced the SR response in a dosedependent manner when injected into the haemolymph of an almost intact animal or perfused over an isolated thorax preparation in which head, abdomen, gut and the entire central nervous system were removed (threshold at 5×10−8moll−1, maximal effect at 5×10−4moH−1 DL-octopamine). The SR was as sensitive to D-octopamine, the naturally occurring isomer of octopamine, as it was to DLoctopamine. Serotonin was equal to octopamine in effectiveness, followed in order of potency by synephrine, metanephrine and tyramine. Dopamine was ineffective. Phentolamine, but not DL-propranolol, antagonized the action of octopamine. The threshold of the modulatory effect of octopamine on the SR suggests that the increased haemolymph octopamine level which occurs during flight is sufficient to increase the SR activity. Two observations suggest that dorsal unpaired median (DUM) cells are involved in the octopaminergic modulation of the SR during flight: (1) selective stimulation of these cells modulated the SR response and this effect was blocked by phentolamine; and (2) a number of DUM cells were activated during flight. These results suggest that the SR activity is enhanced by octopamine following the onset of flight. Since the SR is involved in the control of wing beat frequency, the modulation of the SR might influence the generation of the motor pattern in flying locusts.

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