Species-specific attraction of migratory banded kokopu juveniles to adult pheromones

Juvenile migratory Galaxias fasciatus juveniles or whitebait were attracted to odours produced by adults. The attraction was dependent on concentration with an upstream movement and attraction to the odour chamber at intermediate level concentrations. At a high concentration the migratory response of whitebait was retarded with the majority of fish not moving upstream but remaining in the lower section of the apparatus. There was no response to odours from adults of other galaxiid species, the inanga G. maculatus or koaro G. brevipinnis at any concentration. These results demonstrate G. fasciatus whitebait have the ability to discriminate species-specific pheromones during their migratory phase, providing evidence of a pheromonal attraction in migratory amphidromous fish which could possibly provide a basis for effective habitat selection.     

ALGAL‐RELATED TASTES AND ODORS IN PHOENIX WATER SUPPLY: PRELIMINARY REPORT

Frequent episodes of algal‐related tastes and odors (T & O) in drinking waters in metropolitan Phoenix, Arizona prompted initiation of a three‐year project in July 1999 to investigate the occurrence of T & O metabolites and to develop a comprehensive management strategy to reduce the problems in drinking water supplies in arid environments. Two metabolites, 2‐methylisoborneol (MIB) and geosmin, have been identified as compounds responsible for the earthy‐musty tastes and odors in water supplies. Both were detected in the water supply system, including source rivers, reservoirs, canal delivery system and water treatment plants. Higher concentrations of MIB and geosmin occurred in distribution canals than in the upstream reservoirs indicating that significant production of the T & O compounds occurs within the canal system. A baseline‐monitoring program has been established for the complex water supply system, with special emphasis on the canal system. Efforts are underway to investigate possible correlations between physical/chemical parameters, algal composition and biomass, with the occurrence of MIB and geosmin. In addition, several physical and chemical treatments are planned for the canal system to reduce algal growth and related MIB and geosmin concentrations.     

RESURRECTION OF MESOPLODON TRAVERSII (GRAY, 1874), SENIOR SYNONYM OF M. BAHAMONDI REYES, VAN WAEREBEEK, CÁRDENAS AND YÁÑEZ, 1995 (CETACEA: ZIPHIIDAE)

Mesoplodon traversii (Gray, 1874) is shown to be a senior synonym of the recently described beaked whale Mesoplodon hahamondi Reyes et al. , 1995 on the basis of a phylogenetic analysis of mitochondrial DNA control region sequences. The mandible and teeth of M. traversii , first reported in 1873 by Hector as Dolichodon layardii . are redescribed. The species can be distinguished by features of the calvaria; including the large jugal, broad rostrum, and small distance between premaxillary foramina. The male teeth, which are large and spade-shaped with a strong terminal denticle, are also diagnostic. M. traversii is known only from Pitt Island and White Island, New Zealand and Robinson Crusoe Island, Juan Fernandez Archipelago, Chile.     

The fate of Mus domesticus demes after destruction of their habitats

To test our hypothesis that gene flow has the potential to prevent genetic isolation of crib populations separated by several kilometres, we caught and marked 137 house mice leaving six cribs being emptied of corn. In an attempt to recapture the mice, we set traps just after crib emptying and again, where feasible, 1–2 months later, in areas surrounding cribs (trap-nights/trap-area in hectares:cultivated fields, 3834/29.4; non-cultivated areas, 2238/4). Additional trapping was carried out near nine empty cribs and in eight cultivated fields (3304 trap-nights, 17.7 ha trap-area), each more than 120 m from cribs. After the six cribs were emptied, we recaptured 11% of the crib mice (distance from the crib:mean 81 m, range 0–570 m). In refuge habitats, away from cribs, a breeding population existed and three crib females bred there after emptying of cribs. In demonstrating long dispersal distances and breeding populations away from cribs, our data support the hypothesis that gene flow is potentially large enough to prevent genetic isolation of crib populations separated by expanses of cultivated and uncultivated terrain. The influence of decreased recruitment on gene migration is unclear. Potential predators on nestlings, such as Norway rats, deermice, shrews and voles, escaped from and were trapped outside cribs.     

A novel E box/AT-rich element is required for muscle-specific expression of the sarcoplasmic reticulum Ca2+-ATPase (SERCA2) gene.

The cardiac/slow twitch sarcoplasmic reticulum (SR) Ca2+-ATPase gene (SERCA2 ) encodes a calcium transport pump whose expression is regulated in a tissue- and development-specific manner. Previously we have identified two distinct positive regulatory regions (bp -284 to -72 and -1815 to -1105) as important for SERCA2 promoter activity. Here we demonstrate that the SERCA2 distal promoter region functions like an enhancer by activating a heterologous promoter (TK) in a muscle cell-specific manner. Through deletion analysis a core enhancer region was delimited to the -1467 to -1105 bp fragment. We identified the E box/AT-rich element located at -1115 bp as critical for maximal enhancer activity. Gel mobility shift studies revealed that this E box/AT-rich element specifically binds a protein which is induced during Sol8 myogenesis. This region includes two other cis -acting elements, CArG and MCAT, which also bind specific nuclear protein complexes from Sol8 myotubes. Mutagenesis of each of these sites resulted in decreased SERCA/TK-CAT promoter activity. Based on these data, we propose that the E box/AT-rich element may contribute along with CArG and MCAT elements to the overall activation and regulation of the SERCA2 gene promoter.     

Neurons discovered in male Helicoverpa zea antennae that correlate with pheromone-mediated attraction and interspecific antagonism

Responses of single receptor neurons in the antennae of male Helicoverpa zea to sex pheromone components and to behavioral antagonists were recorded using a cut-sensillum extracellular recording technique. Three types of sensilla were identified from sampling 325 male-specific sensilla trichodea located at the lateral edge of antennomeres. The majority of these sensilla (71%) contained a receptor neuron tuned to the principal sex pheromone component (Z)-11-hexadecenal. A second sensillar type (10%) contained a receptor neuron that responded only to (Z)-9-tetradecenal. A third sensillar type (19%) contained a large-spiking neuron tuned to the secondary pheromone component (Z)-9-hexadecenal, but this neuron also could be stimulated to equivalent spike frequencies by the same emitted amounts of (Z)-9-tetradecenal. A smaller-spiking neuron in this sensillar type responded to two compounds known to act only as behavioral antagonists, (Z)-11-hexadecen-1-ol and (Z)-11-hexadecenyl acetate, and to (Z)-9-tetradecenal. Cross-adaptation studies confirmed the presence of one large- and one small-spiking neuron in the third sensillar type. Dose-response studies correlated to collected stimuli amounts showed that the large-spiking neuron in the third sensillar type was equally tuned to (Z)-9-hexadecenal and (Z)-9-tetradecenal, whereas the smaller-spiking neuron was far more sensitive to (Z)-11-hexadecen-1-ol and to (Z)-11-hexadecenyl acetate than to (Z)-9-tetradecenal. Accepted: 29 September 1997     

Responses of cultured rat trigeminal ganglion neurons to bitter tastants

The initial steps in taste and olfaction result from the activation by chemical stimuli of taste receptor cells (TRCs) and olfactory receptor neurons (ORNs). In parallel with these two pathways is the chemosensitive trigeminal pathway whose neurons terminate in the oral and nasal cavities and which are activated by many of the same chemical stimuli that activate TRCs and ORNs. In a recent single unit study we investigated the responses of rat chorda tympani and glossopharnygeal neurons to a variety of bitter-tasting alkaloids, including nicotine, yohimbine, quinine, strychnine and caffeine, as well as capsaicin, the pungent ingredient in hot pepper. Here we apply many of these same compounds to cultured rat trigeminal ganglion (TG) neurons and measure changes in intracellular calcium [Ca2+]i to determine whether TG neurons will respond to these same compounds. Of the 89 neurons tested, 34% responded to 1 mM nicotine, 7% to 1 mM caffeine, 5% to 1 mM denatonium benzoate, 22% to 1 mM quinine hydrochloride, 18% to 1 mM strychnine and 55% to 1 microM capsaicin. These data suggest that neurons from the TG respond to the same bitter-tasting chemical stimuli as do TRCs and are likely to contribute information sent to the higher CNS regarding the perception of bitter/irritating chemical stimuli.