No evidence for extra-pair paternity in the western gull

The genetic mating system of western gulls Larus occidentalis breeding on Southeast Farallon Island, California, was determined using multilocus DNA fingerprints of 33 chicks from 22 broods. No extra-pair paternity (EPP) was found, despite extra-pair copulations (EPCs) occurring. This suggests that paternity guards are effective, and that females gain few genetic benefits from EPCs. The EPP in western gulls concurs with that of other seabirds, reinforcing the idea that seabirds generally have a monogamous genetic mating system.     

Diel interactions between prey behaviour and feeding in an invasive fish, the round goby, in a North American river

1. We studied the diet of the invasive round goby (Neogobius melanostomus) on a diel basis in the Flint River, a warmwater stream in Michigan, U.S.A. Diet and available prey samples were collected seven times over a 24 h period in four consecutive months. The section of river studied lacked zebra mussels (Dreissena polymorpha), the primary prey of adult round gobies elsewhere in the Great Lakes region. 2. Diet changed on a diel basis with hydropsychid caddisfly and chironomid larvae predominating during the day, chironomid pupae dominating in the evening and heptageniid mayflies dominating at night. Simultaneous study of macroinvertebrate drift suggested that caddisfly and chironomid larvae were most likely picked from submerged rocks, chironomid pupae were most likely taken during their emergent ascent and mayflies were either captured from the drift or picked from rocks. 3. The Flint River lacks a diverse darter (Family: Percidae) and sculpin (Family: Cottidae) fauna and it appears that the round goby has occupied a generalised darter/sculpin niche. Our results indicate that round gobies have the potential to invade successfully riverine systems, particularly those lacking a diverse benthic fish assemblage.     

Methodologies for testing a pluralist idea for the maintenance of sex

The paradox of sex, despite decades of attention, remains unresolved. Recent efforts to gain insight into the nature of the mechanisms underlying the maintenance of sex have led to an emphasis on a pluralist approach, with a particular focus on interaction between multiple mechanisms. However, few empirical tests of pluralist models exist, perhaps due to the widely held assumption that major complications inevitably accompany such tests. Here, we address this issue by providing an overview of how testing of a pluralist idea for the maintenance of sex could be achieved. We also suggest a more specific methodology designed to test for interactive effects between Muller's ratchet and Red Queen dynamics, two models that are widely seen as providing potentially general explanations for the maintenance of sex.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 89 , 605–613.     

Development of Serotonergic Neurons in Embryos of the Sea Urchin, Strongylocentrotus purpuratus

The development of the serotonergic component of the nervous system of larvae of S. purpuratus is traced using indirect immunofluorescence with a polyclonal antibody against the neurotransmitter serotonin. Initially one or two neuroblasts can be detected in the thickened epithelium of the animal plate of late gastrulae (56 hr). The number of immunoreactive cells increases to about eight during formation of the pluteus (85–90 hr). Immunoreactive axons appear simultaneously from all neuroblasts present in the 79 hr prism stage larva and form the apical ganglion. It is proposed that this component of the larval nervous system is derived from a small number of ectodermal cells associated with the apical tuft.     

Localization and Characterization of an Integral Membrane Protein Antigen Expressed by Pigment Cells in Embryos of the Sea Urchin Strongylocentrotus purpuratus

Chromogenic mesenchymal cells in plutei of the sea urchin Strongylocentrotus purpuratus express a tissue specific epitope recognized by the monoclonal antibody Sp–1. In transmission electron micrographs of pre-embed immunoperoxidase labelled plutei, the epitope is localized to pigment cell surfaces. Cell membranes of epidermal cells apposed to pigment cells are also immunoreactive, but endodermal cells apposed to pigment cells are not. Separation of Sp–1 immunoreactive material into the aqueous phase after embryo extraction in butanol indicates that the antigen is a protein or glycoprotein, and other solubilization characteristics suggest that it is an integral membrane constituent. The epitope is destroyed by general proteases and treatment with guanidine hydrochloride, and is resistant to oxidation by periodate and glycosyloxidases, suggesting that it is peptide rather than carbohydrate. On immunoblots of whole embryo extracts, or after SDS-PAGE analysis of ³⁵S-methionine-labelled embryos immunoprecipitated with Sp–1, a band showing an apparent molecular mass of 110 kD is seen at all stages from mid-gastrula to 26-day pluteus. We conclude that the Sp–1 antigen is a 110 kD integral membrane protein which may interact with the epidermal cells over which the pigment cells migrate.     

In Vitro and In Situ Properties of Cell Wall Pectinmethylesterases From Mung Bean Hypocotyls

Pectinmethylesterases (EC 3.1.1.11 [EC] ) have been solubilized fromyoung and mature tissues of mung bean hypocotyls. Whatever theplastic potential of the tissues, most of the pectinmethylesteraseactivity was located in the cell walls. Several active fractionswere obtained after chromatography on CM Sépharose. Equilibriumsedimentation in an analytical ultracentrifuge indicated theMW of the isolated isoforms to be close to 75 000 whereas SDS-PAGEelectrophoresis gave a MW around 32 000, suggesting the possibilityof dimeric structures. Mung bean pectinmethylesterase (PME)showed cross reactivity with soybean antiserum. Experiments carried out with p-nitrophenylacetate and Citruspectin revealed that PME and esterase activities might correspondto different isoforms. It was also noted that the stimulationinduced by cations was stronger when the enzymes were boundto the cell walls. The high ionic sensitivity suggested that,in situ, the ionic environment regulates pectinmethylesteraseactivity principally by modifying the pectin molecules, whichenhances the affinity of the enzymes for their substrate. Thesedata indicate the importance of the calcium content of the cellwalls and might explain the decrease in methylated pectins alongthe mung bean hypocotyl and, in turn, the loss of plasticity. Key words: Cell wall, hypocotyl, pectinmethylesterase, Vigna radiata     

Early Development of Eimeria Papillata (Apicomplexa: Eimeriidae) In the Mouse

ABSTRACT Early development of Eimeria papillata (Apicomplexa) in the mouse was evaluated using Nomarski interference-contrast and brightfield microscopy. Sporozoite-shaped meronts, which were motile and contained a large posterior refractile body and a smaller anterior refractile body, were observed entering and leaving host cells in the jejunum of an experimentally infected mouse at 26 h post inoculation (HPI). However, early developmental stages were not observed in tissue of the duodenum, ileum, cecum and colon. the mean length and width of these meronts (n = 20) were 12.0 μm and 3.7 μm, respectively. Spherical or subspherical meronts containing crescent-shaped merozoites were observed at 36 HPI.     

Septic tanks as larval habitats for the mosquitoes Aedes aegypti and Culex quinquefasciatus in Playa‐Playita,Puerto Rico

Adult Aedes aegypti (Linnaeus) (Diptera: Culicidae) were previously recovered from emergence traps on septic tanks in southeastern Puerto Rico. In this study we quantified immature mosquito abundance and its relationship with structural variables of the septic tanks and chemical properties of the water containing raw sewage. A miniaturized floating funnel trap was used to sample 89 septic tanks for larvae in the Puerto Rican community of Playa‐Playita. Aedes aegypti larvae were recovered from 18% of the sampled tanks (10.3 larvae per septic tank per day). Larval presence was positively associated with cracking of the septic tank walls and uncovered access ports. Larval abundance was positively associated with cracking of the septic tank walls and larger tank surface areas, and inversely associated with the total dissolved solids (TDS). Culex quinquefasciatus (Say) larvae were also recovered from 74% of the septic tanks (129.6 larvae per septic tank per day). Larval presence was negatively associated with TDS in the water and larval abundance was positively associated with cracking of the septic tank walls. A screened, plastic emergence trap was used to sample 93 septic tanks within the community for Ae. aegypti and Cx. quinquefasciatus adults. Aedes aegypti adults were recovered from 49% of the sampled tanks (8.7 adults per septic tank per day) and Cx. quinquefasciatus adults were recovered from 97% of the sampled tanks (155.5 adults per septic tank per day). Aedes aegypti adult presence was positively associated with cracking, uncapped openings and septic water pH. The Ae. aegypti adult counts were positively associated with cracking and inversely associated with TDS and conductivity. This study marks the first published record of the recovery of Ae. aegypti larvae from holding tanks containing raw sewage in the Caribbean region. Our study indicates that Ae. aegypti larvae are present in sewage water and that septic tanks have at least the potential to maintain dengue transmission during the dry season.     

Unusual sex roles in a highly promiscuous parrot: the Greater Vasa Parrot Caracopsis vasa

We describe the unusual mating system of the Greater Vasa Parrot Caracopsis vasa . The dull black plumage of males and females is similar but females are significantly larger than males. Females are promiscuous and copulated with at least five different males. Copulations were either short (1–3 s) or very long (mean 35.9 min), and long copulations involved a copulatory tie facilitated by the male's enlarged cloacal protrusion. Multilocus DNA fingerprinting of 17 broods showed that all were of mixed paternity, and that some broods had three fathers. Males never visited nests directly, but during the incubation and chick-rearing periods females came off the nest and were fed regurgitated fruit by multiple males. Four had band-sharing coefficients that suggested they were unrelated. Males copulated with and provided food for several widely separated females simultaneously. During the chick-rearing period females defended a territory around the nest from conspecific females, developed conspicuous orange skin on the head (through feather loss), and uttered loud, complex vocalizations that we refer to as 'song' from prominent perches near the nest. Males showed none of these traits. Females with high song rates attracted more males and as a result received more food than other females. Play-back experiments in which female song rates were either increased or decreased, attracted more or fewer males respectively. We propose that female song, conspicuous head colour and territoriality have all evolved as a result of competition between females for the food provided by males. The selective pressures favouring this highly unusual breeding system in the Greater Vasa Parrot are unclear but some sort of ecological constraint, such as food availability, may be important.     

BOOK REVIEWS

Multiple Medical Realities: Patients and Healers in Biomedical, Alternative and Traditional Medicine . Helle Johannessen and Imre Lazar, eds. New York: Berghahn Books, 2006. 202 pp.
Spiritual Transformation and Healing: Anthropological, Theological, Neuroscientific, and Clinical Perspectives . Joan D. Koss-Chioino and Philip Hefner, eds. Lanham, MD: AltaMira Press, 2006. 300 pp.