Structure of the olfactory receptor organs, their GABAergic neural pathways, and modulation of mating behavior, in the giant freshwater prawn,Macrobrachium rosenbergii

Abstract

In the giant male prawn, Macrobrachium rosenbergii, the olfactory system is thought to be the main pathway for modulating sexual behavior through pheromone perception. In this report, we first used gross anatomical, histological, and SEM methods to describe the structures of the olfactory receptors (sensilla setae), their neural pathways, and possible role in modulating mating behavior. On the surfaces of antennule and antenna filaments there are four types of sensory receptors, viz single spike-like setae, single flagellum-like setae, multiple flagella-like setae, and aesthetascs (ASs). The ASs, which had previously been proposed to be odor receptor setae, are found only on the short filament of lateral antennule (slAn). Each AS on the slAn connects with olfactory receptor neurons (ORNs), whose axons form an outer central antennule nerve (ocAnNv), which then connects with the olfactory neutrophil (ON) of the brain. Thus, the slAn is the major olfactory organ that conveys sensory inputs from each AS to the ON within the deutocerebrum. GABA immunoreactivity was present in ASs, neurons of ORNs, inner central antennular, lateral tegumentary nerve, ocAnNv and the ON, inferring that GABA is the likely neurotransmitter in modulating olfaction. Disruption of the slAn by ablation or covering with Vaseline, resulted in significant reduction of mating behavior, indicating that this organ is crucial for sex pheromone perception. Identification of the active pheromones and further bioassays are now being performed.

Male morphotypes and alternative mating tactics in freshwater prawns of the genus Macrobrachium: a review

“…The involvement of pheromones in the mating behaviour of M. rosenbergii was suggested by Ling () about 50 years ago but was only recently directly (Thomas ; Al‐Mohsen ) and indirectly (Kruangkum et al . ) confirmed. Al‐Mohsen () tested chemical attraction in prawns of both genders in an elongated flow‐through apparatus that was surveyed by a remotely controlled camera.…”

“…Scanning electron microscopy revealed the presence of four different sensory receptors on the lateral antennules of males, among them the aesthetascs, which probably are involved in pheromone perception leading to mating behaviour (Kruangkum et al . ).…”

“…A detailed study of the structure of the antennal gland of M. rosenbergii BC males carried out with light and transmission electron microscopy (Kruangkum et al . ), revealed a structure with four clear components, the coelomosac, the nephridial tubules, the labyrinth and the bladder. However, the source of the male sex pheromone remained undetected.…”

Neuromuscular transmitter candidates of a centipede (Lithobius forficatus, Chilopoda)

“…Thus, on the level of fluorescence microscopy, GABA and its synthesizing enzyme, GAD, are clearly located within the sensory cells. To our knowledge, the only other report of the possible presence of GABA in arthropod sensory cells is on the aesthetascs of freshwater prawns [ 50 ]. Outside the arthropods, GABA-IR sensory neurons can be found e.g.…”

Social Behaviour and Recognition in Decapod Shrimps, with Emphasis on the Caridea

“…In Macrobrachium rosenbergii, the anatomy of the olfactory receptors, aesthetascs, and neural pathway to the brain have been examined (Kruangkum et al 2013). Ablation of the lateral antennule (bearing aesthetascs) in males significantly reduced the mating success, but ablation of the antenna also caused a reduction in success.…”