Mate Recognition Pheromone Research Articles

Genetic determinants of mate recognition in Brachionus manjavacas(Rotifera)

BackgroundMate choice is of central importance to most animals, influencing population structure, speciation, and ultimately the survival of a species. Mating behavior of male brachionid rotifers is triggered by the product of a chemosensory gene, a glycoprotein on the body surface of females called the mate recognition pheromone. The mate recognition pheromone has been biochemically characterized, but little was known about the gene(s). We describe the isolation and characterization of the mate recognition pheromone gene through protein purification, N-terminal amino acid sequence determination, identification of the mate recognition pheromone gene from a cDNA library, sequencing, and RNAi knockdown to confirm the functional role of the mate recognition pheromone gene in rotifer mating.ResultsA 29 kD protein capable of eliciting rotifer male circling was isolated by high-performance liquid chromatography. Two transcript types containing the N-terminal sequence were identified in a cDNA library; further characterization by screening a genomic library and by polymerase chain reaction revealed two genes belonging to each type. Each gene begins with a signal peptide region followed by nearly perfect repeats of an 87 to 92 codon motif with no codons between repeats and the final motif prematurely terminated by the stop codon. The two Type A genes contain four and seven repeats and the two Type B genes contain three and five repeats, respectively. Only the Type B gene with three repeats encodes a peptide with a molecular weight of 29 kD. Each repeat of the Type B gene products contains three asparagines as potential sites for N-glycosylation; there are no asparagines in the Type A genes. RNAi with Type A double-stranded RNA did not result in less circling than in the phosphate-buffered saline control, but transfection with Type B double-stranded RNA significantly reduced male circling by 17%. The very low divergence between repeat units, even at synonymous positions, suggests that the repeats are kept nearly identical through a process of concerted evolution. Information-rich molecules like surface glycoproteins are well adapted for chemical communication and aquatic animals may have evolved signaling systems based on these compounds, whereas insects use cuticular hydrocarbons.ConclusionOwing to its critical role in mating, the mate recognition pheromone gene will be a useful molecular marker for exploring the mechanisms and rates of selection and the evolution of reproductive isolation and speciation using rotifers as a model system. The phylogenetic variation in the mate recognition pheromone gene can now be studied in conjunction with the large amount of ecological and population genetic data being gathered for the Brachionus plicatilis species complex to understand better the evolutionary drivers of cryptic speciation.

Sex pheromones in Nereis succinea

Summary Female Nereis succinea release a pheromone while swimming around prior to any release of gametes. The pheromone triggers the same response in female worms as the recently described coelomic fluid-derived pheromone. The analysis of seawater samples revealed their structures to be identical. Cysteinyl-glutathione disulfide or Nereithione acts, therefore, as a mate recognition pheromone in the first place and initiates the nuptial dance. The pheromone is released in large amounts yielding an average of 85μg per female.

Chemical ecology of rotifers

One of the primary channels of sensory input for zooplankton are chemical signals. Much zooplankton behavior is triggered by chemical stimuli, including feeding, predator defense, mating, and migration. Chemically regulated zooplankton behavior affects larger scale ecosystem processes like grazing, recruitment and secondary production. Knowledge of how chemicals transmit information about location, food quality, conspecifics, competitors, and predators is critical for understanding how aquatic ecosystems function. This paper reviews the behavioral evidence that planktonic rotifers respond to a variety of chemical stimuli. Although a rich variety of rotifer behaviors are regulated by chemical signals, little progress has been made to isolate and characterize these stimuli. If aquatic ecology is to become a predictive science, knowledge of the mechanisms causing the observed interactions is necessary. Chemical signals need to be isolated, purified, and characterized, and their causal role in regulating population and community processes needs to be demonstrated. Rotifers have chemosensory neurons in their corona and electron microscopy has revealed chemoreceptive pores in the anterior integument of several species. Some rotifers use these chemoreceptors to discriminate food particles based on the flavors on the cell surface. In Asplanchna, prey are discriminated by contact chemoreception. Asplanchna releases a waterborne signal that induces spine formation in several Brachionus species, Keratella cochlearis, K. slacki, and Filinia longisecta. The colonial Sinatherina socialis is defended against fish predation by warts containing unpalatable chemicals that have yet to be identified. Larval settlement in Collotheca gracillipes is determined by the chemistry of aquatic plant surfaces. Larvae prefer the undersurface of leaves where there is a low Ca{++} microhabitat due to photosynthesis. Oviposition in Euchlanis dilatata is restricted to plant surfaces familiar to the maternal female. Hydrogen peroxide and certain prostaglandins stimulate resting egg hatching even in the dark. Sexual reproduction and polymorphism in Asplanchna sieboldi is regulated by dietary tocopherol. A chemical signal that allows assessment of conspecific population density is detected in conditioned media by several rotifer species. Water soluble extracts of Brachionus plicatilis increase mictic female production 1.7 times more than controls. Unknown compounds produced by certain bacteria also increase mixis 4–10 fold over controls. Mate recognition in B. plicatilis is determined by a 29 kD surface glycoprotein called the mate recognition pheromone (MRP). The MRP has been isolated, purified, and a polyclonal antibody against it has been prepared. The structure of the oligosaccharide and protein components of the MRP are currently being characterized. Elucidation of the chemicals regulating rotifer life cycles will make important contributions to the understanding of ecological processes in aquatic communities.

Surface glycoproteins potentially involved in mate recognition in nine freshwater rotifer species

A surface glycoprotein in the marine rotifer Brachionus plicatilis functions as a contact mate recognition pheromone (MRP). A polyclonal antibody to this glycoprotein (anti-MRP) binds to the body surface of nine freshwater rotifer species at sites important in mating behavior of the species studied. Binding among brachionid species was concentrated in the corona and foot as expected from previous observations of mating behavior. In non-brachionid species other than bdelloids, binding occurred in areas where males contacted females and initiated mating. Although the antibody bound to female Brachionus calycifloris, it did not decrease the number of male mating attempts. These results are discussed in light of other research on anti-MRP blokkage of male mating in B. plicatilis and B. rotundiformis strains.

Characteristics of the mate‐recognition pheromone inbrachionus plicatilis(rotifera)

The chemical recognition systems used by aquatic invertebrates to discriminate mates are poorly understood. We describe the results of analysis of a surface glycoprotein that serves as a mate‐recognition pheromone (MRP) for the marine rotifer Brachionus plicatilis. Binding of a polyclonal antibody to the MRP signal on females is described. The binding of anti‐MRP to purified MRP in nitrocellulose membranes is non‐linear. Anti‐MRP also can be used to detect MRP in crude homogenates of rotifer proteins where MRP comprises 0.06 to 0.14% of total protein. As little as 1–2 ng of MRP can be detected in crude homogenates. We estimated that a single B. plicatilis female has about 0.11 ng of MRP concentrated primarily in her corona. Males can discriminate conspecific females from those of other species, females from different geographic populations, and males from females in their own populations. Monosaccharide analysis of the MRP demonstrated the presence of mannose, glucose, N‐acetylglucosamine, fucose, and N‐a...

Mating behavior and mate recognition pheromone blocking of male receptors in Brachionus plicatilis M�ller (Rotifera)

Mating behavior and mate recognition pheromone blocking of male receptors in Brachionus plicatilis M�ller (Rotifera)

Localization of the mate-recognition pheromone in Brachionus plicatilis O.F. Müller (Rotifera) by fluorescent labeling with lectins

Mate-recognition in the rotifer Brachionus plicatilis O.F. Müller is based upon male contact chcmoreception of a glycoprotein pheromone on the body surface of females. The highest densities of this glycoprotein were found on the corona of females as determined by fluorescence microscopy. A time series experiment demonstrated that binding sites on the corona fluoresced before any other structure and did so most intensely. The lorica margin of females fluoresced weakly after 20 min of exposure, suggesting that the mate-recognition pheromone (MRP) is present, but in low density. In males, the corona also was the most intensely labeled structure on the body surface. Pretreatment of rotifers with the lectins Concanavalin A, (ConA), Lens culinaris, Vicia faba and Pisum sativum blocked subsequent labeling with ConA-fluoroisothiocyanate (FITC). Exposure to other lectins did not block ConA-FITC-labeling. Quantitation of fluorescence intensity using image analysis demonstrated that the contrast between a glycoprotein signal and background ranged from 2 to 19.5. In situ degradation of the MRP by the glycohydrolasc N-glycanase reduced lectin-binding and the intensity of fluorescent-labeling. Since N-glycanase deglycosylation of glycoprotcin on the body surface of live females sharply reduced their ability to elicit male-mating reactions, it is clear that the same oligosaccharides critical for lectin-binding also are essential for male-recognition. These lectin probes have enabled us to visualize the distribution of the MRP on the body surface of females and provided insight into the copulatory behavior of males.