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Notes: Abstract Predators such as crabs, whelks, and sea stars attack their bivalve prey in different ways, and predator-induced defenses are an important means of protection. The degree to which induced defenses are specific to different predators, however, remains largely unknown. In laboratory experiments (June to August 1998), we raised mussels (Mytilus edulis L.) in the presence of a drilling predator [the whelk Nucella lapillus (L.)] or a crushing predator [the crab Carcinus maenas (L.)] to determine whether induced changes in prey shell thickness, size, or shape occurred and whether changes were predator-specific. Over a 2 month period, juvenile mussels were exposed to waterborne cues from actively feeding crabs or whelks. Mussels produced thicker shell lips in response to both predators relative to control mussels raised in their absence, and the difference was significantly greater in response to whelks than to crabs. Mussels exposed to whelks showed significantly smaller increases in shell length and width and total wet weight than did mussels exposed to crabs. Thus, there may be a trade-off between shell thickness and linear shell growth and a potential delay in attaining a size refuge from predation.

Notes: Abstract  Most studies characterizing successful biological invaders emphasize those traits that help a species establish a new population. Invasions are, however, multi-phase processes with at least two phases, dispersal and introduction, that occur before establishment. Characteristics that enhance survival at any of these three phases will contribute to invasion success. Here, we synthesize information on the dispersal, introduction, and establishment of fishes mediated by ship ballast-water transport. We synthesize 54 reports of at least 31 fish species collected from ballast tanks (Phase 1), including 28 new reports from our recent studies (1986 to 1996). Our literature survey revealed 40 reports of 32 fish species whose introductions have been attributed to ballast transport (Phase 2), of which at least 24 survived to establish persistent populations (Phase 3). We detected little overlap at the species level between these two data sets (Phase 1 vs Phases 2 and 3), but patterns emerged at the family level. The Gobiidae (6 species), Clupeidae (4 species), and Gasterosteidae (1 species) were the most commonly found fish families in ballast tanks (Phase 1). The Gobiidae (13 species), Blenniidae (6 species) and Pleuronectidae (2 species) dominated the list of ballast-mediated introductions (Phase 2); gobies and blennies were the families most frequently established (Phase 3). The invasive success of gobies and blennies may be explained in part by their crevicolous nature: both groups seek refuge and lay eggs in small holes, and may take advantage of the ballast-intake holes on ship hulls. This behavior, not typically associated with invasive ability, may contribute to successful introduction and establishment by facilitating the dispersal phase of invasion. The failure of the pleuronectids to invade may reflect poor salinity match between donor and recipient regions. To develop a predictive framework of invasion success, organisms must be sampled at all three phases of the invasion process. Our comparison of two ballast sampling methods suggests that fishes have been undersampled in ballast-water studies, including our own, and that the role of ballast transport in promoting fish invasions has been underestimated.

Notes: Abstract. The homologue of the vertebrate complement component C3 that is expressed in the coelomocytes of the purple sea urchin, Strongylocentrotus purpuratus, designated SpC3, was investigated for changes in response to immune challenge or injury. Immunoquiescent animals were used in this study because they have reduced or no detectible SpC3 in their coelomocytes or coelomic fluid (CF). Animals were injected with lipopolysaccharide (LPS) or sterile sea water (SSW, injury control). Changes in the amounts of SpC3 in coelomic fluid and in coelomocytes were then followed over time by Western blots and ELISA. Changes in mRNA from the SpC3 gene (Sp064) were also followed by RT-PCR. Although all animals responded to injury with increased levels of SpC3 in the coelomic fluid, those challenged with LPS had greater amounts of SpC3 in both CF and coelomocytes than those receiving SSW. In most of the animals receiving LPS, initial increases in SpC3 were observed within 1 h post-injection, while the earliest response in the animals receiving SSW was 6 h. The appearance of SpC3 in the coelomocytes was delayed compared to its appearance in CF, and was first detected several days after challenge. Changes in mRNA from the Sp064 gene paralleled the appearance of SpC3 in the coelomic fluid. Increases in the number of coelomocytes per milliliter of CF and in the percentage of coelomocytes that were SpC3+ also occurred after challenge with LPS or in response to injury, with a slightly greater increase in response to LPS. Although the changes in SpC3 were not as great as those identified previously for human C3 expressed in macrophages, the kinetics of the response are similar to that of acute-phase reactants in mammals.

Notes: Abstract. The lower deuterostomes, including the echinoderms, possess an innate immune system that includes a subsystem with similarities to the vertebrate complement system. A homologue of the central component of this system, C3, has recently been identified in the purple sea urchin, Strongylocentrotus purpuratus, and is called SpC3. We determined previously that coelomocytes specifically express the SpC3 gene (Sp064); however, the sea urchin has at least four different types of coelomocytes: amoeboid phagocytes, red spherule cells, colorless spherule cells, and vibratile cells. To determine which of these subpopulations expresses Sp064 and produces SpC3, coelomocytes were separated by discontinuous gradient density centrifugation. Relatively homogenous fractions were obtained consisting of the four major cell types in addition to two types of amoeboid phagocytes with different densities and distinct morphologies. Analysis of proteins from separated cell subpopulations by Western blot and analysis of gene expression by RT-PCR revealed that phagocytes express the gene and contain the protein. Immunolocalization showed that SpC3+ phagocytes are present as subsets of both the low- and high-density subpopulations of phagocytes; however, the subcellular localization of SpC3 is different in these two subpopulations.

Notes: Using a simulated employment contract negotiation, this study examined the relationship between negotiation strategies and the quality of negotiated outcomes. A log-linear analysis showed that the frequency and sequencing of strategies was systematically related to negotiation outcomes. Impasse negotiations were characterized by the frequent use of contention and sequences that paired similar (either cooperative or competitive) strategies. Settlement was associated with decreased contention and the use of sequences that paired dissimilar strategies. Increasing joint gain was linked to the introduction of priority information and conciliation as well as to changes in the pattern of information exchange: Reciprocal and indirect (positional) information exchange led to low joint gain, whereas reciprocal and direct (priority) information exchange led to high joint gain.

Notes: The origin of adaptive immunity in the vertebrates can be traced to the appearance of the ancestral RAG genes in the ancestral jawed vertebrate; however, the innate immune system is more ancient. A central subsystem within innate immunity is the complement system, which has been identified throughout and seems to be restricted to the deuterostomes. The evolutionary history of complement can be traced from the sea urchins (members of the echinoderm phylum), which have a simplified system homologous to the alternative pathway, through the agnathans (hagfish and lamprey) and the elasmobranchs (sharks and rays) to the teleosts (bony fish) and tetrapods, with increases in the numbers of complement components and duplications in complement pathways. Increasing complexity in the complement system parallels increasing complexity in the deuterostome animals. This review focuses on the simplest of the complement systems that is present in the sea urchin. Two components have been identified that show significant homology to vertebrate C3 and factor B (Bf), called SpC3 and SpBf, respectively. Sequence analysis from both molecules reveals their ancestral characteristics. Immune challenge of sea urchins indicates that SpC3 is inducible and is present in coelomic fluid (the body fluids) in relatively high concentrations, while SpBf expression is constitutive and is present in much lower concentrations. Opsonization of foreign cells and particles followed by augmented uptake by phagocytic coelomocytes appears to be a central function for this simpler complement system and important for host defense in the sea urchin. These activities are similar to some of the functions of the homologous proteins in the vertebrate complement system. The selective advantage for the ancestral deuterostome may have been the amplification feedback loop that is still of central importance in the alternative pathway of complement in higher vertebrates. Feedback loop functions would quickly coat pathogens with complement leading to phagocytosis and removal of foreign cells, a system that would be significantly more effective than an opsonin that binds upon contact as a result of simple diffusion. An understanding of the immune response of the sea urchin, an animal that is a good estimator of what the ancestral deuterostome immune system was like, will aid us in understanding how adaptive immunity might have been selected for during the early evolution of the vertebrates and how it might have been integrated into the pre-existing innate immune system that was already in place in those animals.The authors are grateful to Drs Sham Nair and Paul Gross for their critique of the manuscript and helpful suggestions. This work was supported by the National Science Foundation (MCB 9603086).

Notes: We report resonant photoluminescence from CdSe/ZnSe self-assembled quantum dots. When CdSe quantum dots are resonantly excited, excitonic sharp micro-photoluminescence peaks originating from individual quantum dots are strongly enhanced in the region corresponding to optical phonon energies below the excitation. The phonons active in this process are identified as the longitudinal optical (LO) phonons from the CdSe dots, as the interface phonons, and tentatively as the LO phonons from the two-dimensional-like precursor layers. These observations suggest that exciton recombination via phonons is a major relaxation process under resonant excitation. © 2000 American Institute of Physics.

Notes: Background  This population-based study investigated prospectively collected absence for respiratory illness data in two types of formal childcare (centre day care and family day care) in Perth, Western Australia, and factors associated with such absence.Methods  All centres (n = 11) and 95% of family day care caregivers (n = 130) selected at random from licensing lists agreed to participate. Demographic details were obtained from a parental questionnaire and absences were recorded prospectively. Characteristics of the child and family were described using univariate odds ratios (OR) with 95% confidence intervals (CI). Multivariable analysis including generalized estimating equations was used to investigate having at least one absence for respiratory illness, having two or more absences, and having six or more absences.Results  No statistically significant difference between care types for having had at least one absence episode for respiratory illness (OR 1.37, 95% CI 0.92–2.04) was found. Children who attended care for more days per week (OR 1.40, 95% CI 1.26–1.56) and those in the study for more weeks (OR 1.03, 95% CI 1.01–1.05) were more likely to be absent for respiratory illness. Those children in care for a greater number of hours per day were less likely to be absent (OR 0.88, 95% CI 0.80–0.97). Family history of bronchitis was also associated with absence for respiratory illness (OR 1.86, 95% CI 1.32–2.63).Conclusions  Statistically significant factors which had an impact on absence for respiratory illness were primarily those relating to the time spent in childcare and to family history of bronchitis.

Notes: Objectives  This population-based study investigated prospectively collected absence episodes to describe patterns and rates of absences for illness and other reasons in two types of formal childcare. Design Centre day care and family day care homes were selected at random from licensing lists. All centres (n = 11) and 95% of family day care caregivers (n = 130) agreed to participate. The results are based on absence information from carers and on questionnaires to the parents of participating children (n = 846). Results The major reason for absence was respiratory illness with 48% of all children absent at least once during the year with some form of respiratory illness. Although the absence rate for children in centre care was higher than that in family care (3.34 episodes per 52 child–weeks compared with 2.41), the difference was not statistically significant. Conclusion Investigating patterns of absences from childcare allows a better understanding of needs in childcare. The major reason for absence for illness was respiratory illness.

Notes: The present study explored typically developing children’s (n= 77) understanding of physical, cognitive and social competencies of children with impairments. Children in each of four age groups (4–5 years, 6–7 years, 9–10 years and 11–12 years) were interviewed to explore their ideas about the abilities of children with physical impairments (minor: missing thumb; major: wheel-chair bound), sensory impairments (vision and hearing), learning disabilities (non-specific and Down’s syndrome) and emotional/behavioural difficulties (attention deficit hyperactivity disorder and lack of social skills). Significant age differences were found in children’s judgements of the capabilities of children with impairments. Furthermore, children’s understanding of the consequences of impairments varied as a function of disability type. Findings are discussed in relation to previous research on children’s disability concepts and implications for inclusive education practices.