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Understanding how animals maximize reproductive success in variable environments is important in determining how populations will respond to increasingly extreme weather events predicted in the face of changing climates. Although temperature is generally considered a key factor in reproductive decisions, rainfall is also an important predictor of prey availability in arid environments. Here, we test the impact of weather (i.e., rainfall and temperature) on female reproductive investment in an arid-dwelling bird (i.e., clutch size and egg volume) and tradeoffs between the two. We predicted that female chestnut-crowned babblers (Pomatostomus ruficeps), endemic to the arid region of Australia, would increase clutch size at the expense of egg volume in response to variation in rainfall and temperature. We found that over 14 breeding seasons, clutch size decreased with increasing temperature, but increased following more rain. Egg volume, on the other hand, became larger as temperatures increased and, although not related to the amount of rain, was related to the number of days since the last rainfall. Finally, egg size decreased as clutch size increased, indicating a tradeoff between the two reproductive parameters. Our results suggest that chestnut-crowned babblers breed reactively in response to variable environments. We expect that clutch size variation in response to rain may reflect the impact of rain on arthropod abundance, whereas the effect of temperature may represent an established decline in clutch size observed in other seasonal breeders. As the tradeoff between clutch size and egg volume was modest and clutch sizes were modified to a greater extent than egg volumes in response to rainfall, we suggest selection is more likely to increase offspring number than quality, at least in favorable years. Our results support the idea that reproductive investment is variable in fluctuating environments, which has implications for species living in habitats experiencing more extreme and less predictable weather as the global climate changes., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology.)

Budd et al . challenge the identity of neural traces reported for the Cambrian lobopodian Cardiodictyon catenulum. Their argumentation is unsupported, as are objections with reference to living Onychophora that misinterpret established genomic, genetic, developmental, and neuroanatomical evidence. Instead, phylogenetic data corroborate the finding that the ancestral panarthropod head and brain is unsegmented, as in C. catenulum .

The residency and movements of a single acoustically tagged female crested horn shark (Heterodontus galeatus) were monitored in Jervis Bay, Australia. The individual was intermittently detected by receivers throughout the 8-year study period and showed preference for particular rocky reefs in terms of its residency indices and duration of residency events. This individual exhibited lower residency and dissimilar movement patterns to that of the well-studied and sympatric Port Jackson shark (Heterodontus portusjacksoni), highlighting the need for research into the basic life history and movement ecology of H. galeatus., (© 2021 Fisheries Society of the British Isles.)

Introduction: Embryonic growth and development require efficient respiratory gas exchange. Internal incubation of developing young thus presents a significant physiological challenge, because respiratory gas diffusion to embryos is impeded by the additional barrier of parental tissue between the embryo and the environment. Therefore, live-bearing species exhibit a variety of adaptations facilitating respiratory gas exchange between the parent (usually the mother) and embryos. Syngnathid fishes are the only vertebrates to exhibit male pregnancy, allowing comparative studies of the biology and evolution of internal incubation of embryos, independent of the female reproductive tract. Here, we examine the fleshy, sealed, seahorse brood pouch, and provide the first quantification of structural changes to this gestational organ across pregnancy., Methods: We used histological analysis and morphometrics to quantify the surface area for exchange across the brood pouch epithelium, and the structure of the vascular bed of the brood pouch., Results: We show dramatic remodelling of gestational tissues as pregnancy progresses, including an increase in tortuosity of the gestational epithelium, an increase in capillary density, and a decrease in diffusion distance between capillaries and the pouch lumen., Discussion: These changes produce an increased surface area and expansion of the vascular bed of the placenta that likely facilitates respiratory gas exchange. These changes mirror the remodelling of gestational tissue in viviparous amniotes and elasmobranchs, and provide further evidence of the convergence of adaptations to support pregnancy in live-bearing animals., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Insects have evolved diverse and remarkable strategies for navigating in various ecologies all over the world. Regardless of species, insects share the presence of a group of morphologically conserved neuropils known collectively as the central complex (CX). The CX is a navigational center, involved in sensory integration and coordinated motor activity. Despite the fact that our understanding of navigational behavior comes predominantly from ants and bees, most of what we know about the underlying neural circuitry of such behavior comes from work in fruit flies. Here, we aim to close this gap, by providing the first comprehensive map of all major columnar neurons and their projection patterns in the CX of a bee. We find numerous components of the circuit that appear to be highly conserved between the fly and the bee, but also highlight several key differences which are likely to have important functional ramifications., Competing Interests: MS, RT, JC, JK, SH No competing interests declared, (© 2021, Sayre et al.)

Galleria mellonella has risen to fame as an invertebrate model organism given its ethical advantages, low maintenance costs, rapid reproduction time, short life cycle, high number of progeny, tolerance for human body temperatures, innate immune system and similarities to mammalian host models. It is increasingly being utilised to evaluate in vivo toxicity and efficacy of chemical compounds and antimicrobials, modelling microbial (bacterial, fungal and viral) pathogenicity and assessing host-pathogen interaction during infection. During this molecular age of genomic, transcriptomic, proteomic and genetic manipulation approaches, our understanding of microbial pathogenicity and host-pathogen interactions has deepened from high-throughput molecular studies performed in G. mellonella. In this review, we describe the use of G. mellonella in a broad range of studies involving omics, drug resistance, functional analysis and host-microbial community relationships. The future of G. mellonella in the molecular age is bright, with a multitude of new approaches and uses for this model from clinical to biotechnological on the horizon., (© The Author(s) 2021. Published by Oxford University Press on behalf of FEMS. All rights reserved.)

Snakes are descended from highly visual lizards [1] but have limited (probably dichromatic) color vision attributed to a dim-light lifestyle of early snakes [2-4]. The living species of front-fanged elapids, however, are ecologically very diverse, with ∼300 terrestrial species (cobras, taipans, etc.) and ∼60 fully marine sea snakes, plus eight independently marine, amphibious sea kraits [1]. Here, we investigate the evolution of spectral sensitivity in elapids by analyzing their opsin genes (which are responsible for sensitivity to UV and visible light), retinal photoreceptors, and ocular lenses. We found that sea snakes underwent rapid adaptive diversification of their visual pigments when compared with their terrestrial and amphibious relatives. The three opsins present in snakes (SWS1, LWS, and RH1) have evolved under positive selection in elapids, and in sea snakes they have undergone multiple shifts in spectral sensitivity toward the longer wavelengths that dominate below the sea surface. Several relatively distantly related Hydrophis sea snakes are polymorphic for shortwave sensitive visual pigment encoded by alleles of SWS1. This spectral site polymorphism is expected to confer expanded "UV-blue" spectral sensitivity and is estimated to have persisted twice as long as the predicted survival time for selectively neutral nuclear alleles. We suggest that this polymorphism is adaptively maintained across Hydrophis species via balancing selection, similarly to the LWS polymorphism that confers allelic trichromacy in some primates. Diving sea snakes thus appear to share parallel mechanisms of color vision diversification with fruit-eating primates., Competing Interests: Declaration of Interests The authors declare no competing interests., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Simon Baeckens and Raoul Van Damme introduce the phenotypic changes animals and plants undergo when inhabiting islands., (Copyright © 2020 Elsevier Inc. All rights reserved.)

The oyster's immune system is capable of adapting upon exposure to a pathogen-associated molecular pattern (PAMP) to have an enhanced secondary response against the same type of pathogen. This has been demonstrated using poly(I:C) to elicit an antiviral response in the Pacific oyster (Crassostrea gigas) against Ostreid herpesvirus (OsHV-1). Improved survival following exposure to poly(I:C) has been found in later life stages (within-generational immune priming) and in the next generation (transgenerational immune priming). The mechanism that the oyster uses to transfer immunity to the next generation is unknown. Here we show that oyster larvae have higher survival to OsHV-1 when their mothers, but not their fathers, are exposed to poly(I:C) prior to spawning. RNA-seq provided no evidence to suggest that parental exposure to poly(I:C) reconfigures antiviral gene expression in unchallenged larvae. We conclude that the improved survival of larvae might occur via maternal provisioning of antiviral compounds in the eggs., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The olive fruit fly, Bactrocera oleae (Rossi), is the most important insect pest for the cultivation of olives worldwide. Considerable research efforts have been invested in the past decades to develop eradication or suppression tactics for use within an area-wide integrated pest management (AW-IPM) approach that includes a sterile insect technique (SIT) component. One of the major obstacles encountered in the development of SIT for olive fruit fly was the inferior quality of the mass-reared flies, expressed among others evident primarily by sterile males having a different timing of peak mating and a lower mating propensity in comparison with their wild counterparts. In this study we assessed the mating behaviour and mating compatibility of olive fruit flies originating from four countries of the Mediterranean region (Croatia, France, Italy, Spain) in walk-in field cages and post zygotic compatibility (expressed as % egg hatch) under laboratory conditions. Furthermore, we tested the hypothesis whether a hybrid strain (Greece (domesticated)/Israel (wild)) adapted to laboratory rearing conditions showed any mating barriers with all the four "wild" populations. Finally, we examined the effect of colonization on the mating compatibility of the four newly established populations over three consecutive generations. The results showed no pre-zygotic (mating barriers) or post-zygotic isolations (measured by egg hatch%) among the olive fruit fly populations from the four countries tested. Also, there was no evidence of mating barriers between the hybrid strain and the wild populations of the Mediterranean region., Competing Interests: The authors have declared that no competing interests exist.

Subtropical and temperate coastal saltmarsh of Australia is listed as an endangered ecological community under the Commonwealth Environment Protection and Biodiversity Conservation Act (EPBC Act). Saltmarshes are under threat from sea level rise, landward migration of mangroves, and in urban regions from habitat loss, input of litter, nutrients, and other contaminants. In urbanised catchments, saltmarsh areas receive nutrient-enriched and pollutant-contaminated run-off, such as heavy metals, through the stormwater system. This study aimed to investigate the impact of urban stormwater on saltmarsh and mangrove species composition and distribution. To test the effect of stormwater run-off in urbanised catchments on saltmarsh communities, we analysed the soil for pollutant elements, salinity and nutrient concentration and recorded vegetation composition at eight sites in the Sydney region, Australia. We found that elevated total nitrogen (>0.4 wt%) and reduced salinity of the soil downslope of stormwater outlets facilitates establishment of exotic plants and might promote migration of mangroves into saltmarshes, resulting in a squeezing effect on the distribution of saltmarsh vegetation. Saltmarsh cover was significantly lower below stormwater outlets and exotic plant cover increased significantly with sediment calcium concentrations above 8840 mg/kg, which are associated with stormwater run-off. However, this effect was found to be strongest in highly industrialised areas compared to residential areas. Understanding the impact of pollutants on coastal wetlands will improve management strategies for the conservation of this important endangered ecological community., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Worldwide, invasive species are a leading driver of environmental change across terrestrial, marine, and freshwater environments and cost billions of dollars annually in ecological damages and economic losses. Resources limit invasive-species control, and planning processes are needed to identify cost-effective solutions. Thus, studies are increasingly considering spatially variable natural and socioeconomic assets (e.g., species persistence, recreational fishing) when planning the allocation of actions for invasive-species management. There is a need to improve understanding of how such assets are considered in invasive-species management. We reviewed over 1600 studies focused on management of invasive species, including flora and fauna. Eighty-four of these studies were included in our final analysis because they focused on the prioritization of actions for invasive species management. Forty-five percent (n = 38) of these studies were based on spatial optimization methods, and 35% (n = 13) accounted for spatially variable assets. Across all 84 optimization studies considered, 27% (n = 23) explicitly accounted for spatially variable assets. Based on our findings, we further explored the potential costs and benefits to invasive species management when spatially variable assets are explicitly considered or not. To include spatially variable assets in decision-making processes that guide invasive-species management there is a need to quantify environmental responses to invasive species and to enhance understanding of potential impacts of invasive species on different natural or socioeconomic assets. We suggest these gaps could be filled by systematic reviews, quantifying invasive species impacts on native species at different periods, and broadening sources and enhancing sharing of knowledge., (© 2017 Society for Conservation Biology.)

Background: Vessel-associated cells (VACs) are highly specialized, living parenchyma cells that are in direct contact with water-conducting, dead vessels. The contact may be sparse or in large tight groups of parenchyma that completely surrounds vessels. VACs differ from vessel distant parenchyma in physiology, anatomy, and function and have half-bordered pits at the vessel-parenchyma juncture. The distinct anatomy of VACs is related to the exchange of substances to and from the water-transport system, with the cells long thought to be involved in water transport in woody angiosperms, but where direct experimental evidence is lacking., Scope: This review focuses on our current knowledge of VACs regarding anatomy and function, including hydraulic capacitance, storage of nonstructural carbohydrates, symplastic and apoplastic interactions, defense against pathogens and frost, osmoregulation, and the novel hypothesis of surfactant production. Based on microscopy, we visually represent how VACs vary in dimensions and general appearance between species, with special attention to the protoplast, amorphous layer, and the vessel-parenchyma pit membrane., Conclusions: An understanding of the relationship between VACs and vessels is crucial to tackling questions related to how water is transported over long distances in xylem, as well as defense against pathogens. New avenues of research show how parenchyma-vessel contact is related to vessel diameter and a new hypothesis may explain how surfactants arising from VAC can allow water to travel under negative pressure. We also reinforce the message of connectivity between VAC and other cells between xylem and phloem., (© 2018 Botanical Society of America.)

Honeybees are well known for their complex division of labor. Each bee sequentially performs a series of social tasks during its life. The changes in social task performance are linked to gross differences in behavior and physiology. We tested whether honeybees performing different social tasks (nursing versus foraging) would differ in their gustatory responsiveness and associative learning behavior in addition to their daily tasks in the colony. Further, we investigated the role of the biogenic amine tyramine and its receptors in the behavior of nurse bees and foragers. Tyramine is an important insect neurotransmitter, which has long been neglected in behavioral studies as it was believed to only act as the metabolic precursor of the better-known amine octopamine. With the increasing number of characterized tyramine receptors in diverse insects, we need to understand the functions of tyramine on its own account. Our findings suggest an important role for tyramine and its two receptors in regulating honeybee gustatory responsiveness, social organization and learning behavior. Foragers, which were more responsive to gustatory stimuli than nurse bees and performed better in appetitive learning, also differed from nurse bees in their tyramine brain titers and in the mRNA expression of a tyramine receptor in the brain. Pharmacological activation of tyramine receptors increased gustatory responsiveness of nurse bees and foragers and improved appetitive learning in nurse bees. These data suggest that a large part of the behavioral differences between honeybees may be directly linked to tyramine signaling in the brain., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2017. Published by The Company of Biologists Ltd.)

Terrer et al (Reports, 1 July 2016, p. 72) used meta-analysis of carbon dioxide (CO 2 ) enrichment experiments as evidence of an interaction between mycorrhizal symbiosis and soil nitrogen availability. We challenge their database and biomass as the response metric and, hence, their recommendation that incorporation of mycorrhizae in models will improve predictions of terrestrial ecosystem responses to increasing atmospheric CO 2 ., (Copyright © 2017, American Association for the Advancement of Science.)

The Pacific oyster (Crassostrea gigas) is farmed globally. Ostreid herpesvirus (OsHV-1) causes severe mortalities of farmed C. gigas. Management of OsHV-1 has proven difficult. Oysters treated with poly(I:C) exhibit enhanced protection (EP) against OsHV-1. This chemical treatment is highly effective, but it is not feasible to treat every oyster on a farm. To circumvent this practical limitation, previous studies on arthropods have suggested that EP can be transferred from parents to their offspring (trans-generational EP, TGEP). This suggests that the treatment of relatively few parents could be used to produce large numbers of offspring with TGEP. Here, we investigated TGEP in oysters to test whether it might be used as a cost effective management tool to control OsHV-1. We found that offspring (D-veliger larvae) produced from poly(I:C)-treated parents had double the chance of surviving exposure to OsHV-1 compared to controls. Furthermore, the larvae of poly(I:C)-treated parents contained elevated levels of mRNA encoding a key transcription factor that regulates antiviral immunity (IRF2). Poly(I:C) treatment had no effect on the survival of oyster parents. Hence, the enhanced immunity of their offspring could not be explained by genetic selection, and instead may reflect epigenetic reprogramming or maternal provisioning., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

State-space models (SSMs) are increasingly used in ecology to model time-series such as animal movement paths and population dynamics. This type of hierarchical model is often structured to account for two levels of variability: biological stochasticity and measurement error. SSMs are flexible. They can model linear and nonlinear processes using a variety of statistical distributions. Recent ecological SSMs are often complex, with a large number of parameters to estimate. Through a simulation study, we show that even simple linear Gaussian SSMs can suffer from parameter- and state-estimation problems. We demonstrate that these problems occur primarily when measurement error is larger than biological stochasticity, the condition that often drives ecologists to use SSMs. Using an animal movement example, we show how these estimation problems can affect ecological inference. Biased parameter estimates of a SSM describing the movement of polar bears (Ursus maritimus) result in overestimating their energy expenditure. We suggest potential solutions, but show that it often remains difficult to estimate parameters. While SSMs are powerful tools, they can give misleading results and we urge ecologists to assess whether the parameters can be estimated accurately before drawing ecological conclusions from their results.

Stomatal conductance links plant water use and carbon uptake, and is a critical process for the land surface component of climate models. However, stomatal conductance schemes commonly assume that all vegetation with the same photosynthetic pathway use identical plant water use strategies whereas observations indicate otherwise. Here, we implement a new stomatal scheme derived from optimal stomatal theory and constrained by a recent global synthesis of stomatal conductance measurements from 314 species, across 56 field sites. Using this new stomatal scheme, within a global climate model, subtantially increases the intensity of future heatwaves across Northern Eurasia. This indicates that our climate model has previously been under-predicting heatwave intensity. Our results have widespread implications for other climate models, many of which do not account for differences in stomatal water-use across different plant functional types, and hence, are also likely under projecting heatwave intensity in the future.

State-space models provide a powerful way to scale up inference of movement behaviours from individuals to populations when the inference is made across multiple individuals. Here, I show how a joint estimation approach that assumes individuals share identical movement parameters can lead to improved inference of behavioural states associated with different movement processes. I use simulated movement paths with known behavioural states to compare estimation error between nonhierarchical and joint estimation formulations of an otherwise identical state-space model. Behavioural state estimation error was strongly affected by the degree of similarity between movement patterns characterising the behavioural states, with less error when movements were strongly dissimilar between states. The joint estimation model improved behavioural state estimation relative to the nonhierarchical model for simulated data with heavy-tailed Argos location errors. When applied to Argos telemetry datasets from 10 Weddell seals, the nonhierarchical model estimated highly uncertain behavioural state switching probabilities for most individuals whereas the joint estimation model yielded substantially less uncertainty. The joint estimation model better resolved the behavioural state sequences across all seals. Hierarchical or joint estimation models should be the preferred choice for estimating behavioural states from animal movement data, especially when location data are error-prone.

Definitions of learning vary widely across disciplines, driven largely by different approaches used to assess its occurrence. These definitions can be better reconciled with each other if each is recognized as coherent with a common conceptualization of learning, while appreciating the practical utility of different learning definitions in different contexts., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Marine debris, caused by anthropogenic pollution, is a major problem impacting marine wildlife worldwide. This study documents and quantifies the ingestion and defecation of debris by 74 loggerhead sea turtles, Caretta caretta, in the South-West Indian Ocean. Debris was found in 51.4% of gut or fecal samples of loggerheads by-catch from Reunion Island long liners. Anthropogenic debris was ubiquitous in our samples with plastics accounting for 96.2% of the total debris collected. No significant relationship was detected between the characteristics of ingested debris and the biometric characteristics of loggerheads. The number, weight, volume and mean length of debris were higher in gut content of deceased loggerheads than in fecal samples of live turtles, but not significantly, except for the mean length. This is the first record of debris ingestion by sea turtles in the Indian Ocean and our results highlight the magnitude of this pollution of the marine environment., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Rivers provide an excellent system to study interactions between patterns of biodiversity structure and ecological processes. In these environments, gene flow is restricted by the spatial hierarchy and temporal variation of connectivity within the drainage network. In the Australian arid zone, this variability is high and rivers often exist as isolated waterholes connected during unpredictable floods. These conditions cause boom/bust cycles in the population dynamics of taxa, but their influence on spatial genetic diversity is largely unknown. We used a landscape genetics approach to assess the effect of hydrological variability on gene flow, spatial population structure and genetic diversity in an Australian freshwater fish, Macquaria ambigua. Our analysis is based on microsatellite data of 590 samples from 26 locations across the species range. Despite temporal isolation of populations, the species showed surprisingly high rates of dispersal, with population genetic structure only evident among major drainage basins. Within drainages, hydrological variability was a strong predictor of genetic diversity, being positively correlated with spring-time flow volume. We propose that increases in flow volume during spring stimulate recruitment booms and dispersal, boosting population size and genetic diversity. Although it is uncertain how the hydrological regime in arid Australia may change under future climate scenarios, management strategies for arid-zone fishes should mitigate barriers to dispersal and alterations to the natural flow regime to maintain connectivity and the species' evolutionary potential. This study contributes to our understanding of the influence of spatial and temporal heterogeneity on population and landscape processes., (© 2010 Blackwell Publishing Ltd.)

The common brushtail possum (Trichosurus vulpecula) is indeed a common marsupial in major cities of Australia. This species is known to be susceptible to leptospirosis and often lives in close contact with humans, raising concerns about the potential for transmission of this disease in urban areas. A total of 192 brushtail possum blood samples were collected from 136 individuals in suburban areas of metropolitan Sydney from November 2002 to November 2004. Sera were screened against a reference panel of 21 Leptospira spp. using the microscopic agglutination test. Leptospiral antibodies were detected in 9.6% (13/136) of tested brushtail possums and represented two serovars; antibodies to Leptospira interrogans serovar Hardjo were most frequently identified (11/136). A representative of the exotic sero-group Ballum, most likely serovar Arborea, was found in two of 136 brushtail possums. Exposure to leptospirosis seemed to be associated with age, as older animals had a higher incidence, but there was no distinction in relation to gender. Antibody prevalence varied between the different sampling sites and seropositive animals were clustered and restricted to a few sites. These data support the possible role of brushtail possums as a maintenance host for Leptospira spp. in urban environments and also identified them as a previously unknown and potential source of serovar Arborea.

Anthropogenic impacts are believed to be the primary threats to the eastern Australian population of grey nurse sharks (Carcharias taurus), which is listed as critically endangered, and the most threatened population globally. Analyses of 235 polymorphic amplified fragment length polymorphisms (AFLP) loci and 700 base pairs of mitochondrial DNA control region provide the first account of genetic variation and geographical partitioning (east and west coasts of Australia, South Africa) in C. taurus. Assignment tests, analysis of relatedness and Fst values all indicate that the Australian populations are isolated from South Africa, with negligible migration between the east and west Australian coasts. There are significant differences in levels of genetic variation among regions. Australian C. taurus, particularly the eastern population, has significantly less AFLP variation than the other sampling localities. Further, the eastern Australian sharks possess only a single mitochondrial haplotype, also suggesting a small number of founding individuals. Therefore, historical, rather than anthropogenic processes most likely account for their depauperate genetic variation. These findings have implications for the viability of the eastern Australian population of grey nurse sharks.

The common brushtail possum (Trichosurus vulpecula) has well adapted to increasing urbanization, resulting in greater interaction with humans and their domestic pets. Wildlife species in urban areas face a higher risk of exposure to zoonotic pathogens and may be affected by parasites hosted by cats (Toxoplasma gondii) or dogs (Neospora caninum), yet it is unknown to what extent urban T. vulpecula are exposed to these parasites. Antibodies to T. gondii and N. caninum were assayed in sera of 142 adult possums from the city of Sydney, Australia. Using the modified agglutination test, antibodies to T. gondii were found in 9 (6.3%) of the 142 animals in titers of 1:25 (4), 1:50 (1), 1:100 (1), 1:800 (1), 1:3,200 (1), 1:6,400 (1), and 1:12,800 (1). Of some T. vulpecula multiple sera samples within a 2-yr frame could be collected, but seropositive animals in general were not recaptured after initial seroconversion. One possum had a high T. gondii titer on 2 consecutive bleedings, 14 mo apart, and seropositive possums appeared normal when captured. Sex seemed not to have an affect on antibody prevalence, but age and location may play a role. Antibodies to N. caninum were not detected in 1:25 dilution of sera in the N. caninum agglutination test, indicating that T. vulpecula may not have been exposed to this parasite. This is the first serological survey for T. gondii and N. caninum infections in urban T. vulpecula.

Cryptophyte algae contain two kinds of light-harvesting protein, phycobiliproteins and chlorophyll a,c-binding proteins. The beta subunit of the phycobiliprotein phycoerythrin (PE) is encoded in the chloroplast. Genes for the other PE polypeptides are located in the nucleus but little is known of their organization. We cloned and sequenced six cpeA genes encoding the phycoerythrin alpha subunit from a genomic library of the cryptophyte Rhodomonas CS24. Derived peptide sequences of the cpeA genes show that alpha subunits occur in at least two forms, a longer alpha1 form and a shorter alpha2 form. Remarkably, all six cpeA genes occur in divergent pairs encoding one alpha1 and one alpha2 subunit. Four cac genes encoding chlorophyll a,c-binding proteins were cloned and sequenced and also found to occur in divergent pairs comprising one cac1 and one cac2 gene. Inspection of the predicted targeting sequences of the alpha1 and alpha2 phycoerythrin polypeptides shows that only the alpha1 polypeptides have a thylakoid lumen targeting sequence, corresponding to the TAT pathway. Given the previously reported lack of a lumen-targeting sequence on the beta subunit, we propose a novel import mechanism in which the entire alpha1alpha2 betabeta phycoerythrin complex is assembled in the stroma and transported into the thylakoid under the direction of the single targeting sequence on the alpha1 protein. The FAP motif implicated in plastid targeting in diatoms appears to be conserved in this cryptophyte.