The Magelonidae (Annelida: Polychaeta) from the Seychelles, with the description of three new species

Three new species of Magelona are described from the Seychelles: M. conversa, M. falcifera and M. gemmata. Magelona conversa belongs to a 'M. mirabilisgroup', having a rounded prostomium and specialised chaetae on chaetiger 9, but differs from all other members in having long prechaetal neuropodial lamellae on chaetigers 1–8. Magelona falcifera bears large sickle-shaped hooded hooks in the abdomen and thus approaches the genus Meredithia, but lacks prostomial horns. Magelona gemmata belongs to a 'M. longicornis group' in having distinct prostomial frontal horns, and a thorax with lanceolate postchaetal lamellae in the notopodia and ventral neuropodial lobes. The distinctively swollen bud-like tips on the notopodial lamellae of chaetiger 9 are an unique feature. The status of MeredithiaHernández-Alcántara & Solís-Weiss, 2000 and current magelonid terminology are discussed.     

Studies on the chemical nature of feeding stimulants for rainbow trout, Salmo gairdneri Richardson

Rainbow trout trained to operate a demand feeder showed a marked preference for a diet flavoured with a synthetic mixture of chemicals over the unfavoured diet. The gustatory feeding stimulant activity resided in the amino acid fraction and was stereospeciflc for the L-forms. Certain mixtures of L-amino acids were stimulatory, while the individual components of the mixtures were inactive or repellent.     

Neurobiology of Stomotoca. I. Action systems

The layout of nerves, muscles, and conducting epithelia is described for the simple hydrozoan medusa Stomotoca. Comparisons are drawn with Sarsia and other recently studied forms. The major action systems are those responsible for swimming, crumpling (protective involution), tentacle posture, pointing (unilateral reciprocal flexions of the manubrium and margin), and visceral movements (barely mentioned). Crumpling is a simple summating response in this species. Crumpling and pointing are considered to use the same effectors but different conduction pathways. New histological results include the demonstration of a nerve plexus running through the endodermal canal system and a nerve plexus in the ectoderm encircling the peduncle. Special attention is given to the distribution of synapses and gap junctions, as possible trasmission pathways in behavioral responses. Some details are included on organization within the marginal nerve rings.     

Distribution and fate of aliphatic and aromatic hydrocarbons in Antarctic fauna and environment

With the depletion of oil resources in more accessible areas, those of remote regions are being considered or indeed are now being exploited. In many of these regions, especially the polar ones, little is known of the effects such exploitation will have on the environment. But it is known that the ecosystems are often subject to great stress by natural climatic conditions and additional burdens imposed by man may have catastrophic environmental effects. South Georgia, a sub-Antarctic island, has a history of industrial activity mainly concerned with whaling operations that peaked around 1925–1935 but has since declined to virtually nothing. Studies of the ecology of the area provided a unique opportunity to assess the long-term effects that such activities had on the ecosystem. Off the whaling stations a considerable amount of waste material, including fuel oil, was released into the bays and inevitably some of this material was deposited in the sediments. Chemical evidence in the form of both paraffinic and aromatic hydrocarbons still persists in the sediments. The implications of this persistence in relation to the possible influence of the low temperature conditions are discussed. The superficial sediments, marine biota and terrestrial plants, which since 1965 have returned virtually to a pristine state, contain hydrocarbons essentially similar to unpolluted areas around the coast of Britain. Relatively high levels of carcinogenic/mutagenic polynuclear aromatic hydrocarbons in surface sediments suggests a world-wide background of abiogenic hydrocarbons probably disseminated by airborne transport. This appears to indicate that contamination reaches even remote parts of the world in relatively undiminished quantities.     

Complete nucleotide sequence of a cryptic plasmid, pbaw301, from the ruminai anaerobe Ruminococcus flavefaciens R13e2

Abstract The complete nucleotide sequence of a cryptic plasmid designated pBAW301, from the Gram-positive ruminai bacterium Ruminococcus flavefaciens R13e2, has been determined. This plasmid is 1768 bp in size and has an overall G+C content of 43.5%. Computer analysis of the sequence data revealed an open reading frame, ORF1 (256 amino acids), which is similar to the Rep protein of the Bacillus borstelensis plasmid pHT926. ORF1 is preceded by Shine-Dalgarno and Escherichia coli —10 and —35 like sequences. Nine smaller open reading frames showed no significant homologies to known protein sequences. Analysis of replication intermediates and the nucleotide sequence indicate that the plasmid does not replicate by a rolling-circle mode of replication similar to other plasmids from Gram-positive bacteria. Moreover, sequences typical of theta replication origins were not found in the nucleotide sequence of pBAW301. These data suggest that this plasmid either replicates by an as yet undescribed mechanism, or represents a new class of theta replicating plasmids.     

Phosphodiesterase activity and the potentiation by theophylline of adrenocorticotrophin stimulated steroidogenesis and adenosine 3',5'-monophosphate levels in isolated rat adrenal cells

Corticosterone production and adenosine 3′,5′-monophosphate levels in collagenase prepared isolated rat adrenal cells have been measured in response to adrenocorticotrophin in the presence and absence of theophylline. Theophylline (1mM) was found to potentiate the steroidogenic effect of submaximal concentrations of adrenocorticotrophin. This concentration of theophylline was without effect on protein synthesis in this system. Potentiation of adrenocorticotrophin stimulated adenosine 3′,5′-monophosphate levels was also observed in the presence of theophylline (0.5 and 1.0mM). Phosphodiesterase activity in collagenase prepared adrenal cells was 67% of that in intact glands, while the activity in trypsin prepared cells was 37% of that in intact glands.     

Stock structure of Grey Mackerel, Scomberomorus semifasciatus (Pisces: Scombridae) across northern Australia, based on otolith stable isotope chemistry

The stable isotopes of δ¹⁸O and δ¹³C in sagittal otolith carbonates were used to determine the stock structure of Grey Mackerel, Scomberomorus semifasciatus. Otoliths were collected from Grey Mackerel at ten locations representing much of their distributional and fisheries range across northern Australia from 2005 to 2007. Across this broad range (～ 6500 km), fish from four broad locations—Western Australia (S1), Northern Territory and Gulf of Carpentaria (S2, S3, S4, S5, S6, S7), Queensland east coast mid and north sites (S8, S9) and Queensland east coast south site (S10)—had stable isotope values that were significantly different indicating stock separation. Otolith stable isotopes differed more between locations than among years within a location, indicating temporal stability across years. The spatial separation of these populations indicates a complex stock structure across northern Australia. Stocks of S. semifasciatus appear to be associated with large coastal embayments. These results indicate that optimal fisheries management may require a review of the current spatial arrangements, particularly in relation to the evidence of shared stocks in the Gulf of Carpentaria. Furthermore, as the population of S. semifasciatus in Western Australia exhibited high spatial separation from those at all the other locations examined, further research activities should focus on investigating additional locations within Western Australia for an enhanced determination of stock delineation.