Causes of shear sensitivity of the toxic dinoflagellate Protoceratium reticulatum

Dinoflagellates have proven extremely difficult to culture because they are inhibited by low‐level shear forces. Specific growth rate of the toxic dinoflagellate Protoceratium reticulatum was greatly decreased compared with static control culture by intermittent exposure to a turbulent hydrodynamic environment with a bulk average shear rate that was as low as 0.3 s^?1. Hydrodynamic forces appeared to induce the production of reactive oxygen species (ROS) within the cells and this caused peroxidation of cellular lipids and ultimately cell damage. Exposure to damaging levels of shear rate correlated with the elevated level of lipoperoxides in the cells, but ROS levels measured directly by flow cytometry did not correlate with shear induced cell damage. This was apparently because the measured level of ROS could not distinguish between the ROS that are normally generated by photosynthesis and the additional ROS produced as a consequence of hydrodynamic shear forces. Continuously subjecting the cells to a bulk average shear rate value of about 0.3 s^?1 for 24‐h caused an elevation in the levels of chlorophyll a, peridinin and dinoxanthin, as the cells apparently attempted to counter the damaging effects of shear fields by producing pigments that are potential antioxidants. In static culture, limitation of carbon dioxide produced a small but measureable increase in ROS. The addition of ascorbic acid (0.1 mM) to the culture medium resulted in a significant protective effect on lipid peroxidation, allowing cells to grow under damaging levels of shear rates. This confirmed the use of antioxidant additives as an efficient strategy to counter the damaging effects of turbulence in photobioreactors where shear sensitive dinoflagellates are cultivated. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009     

Change across the lifespan in a psychological measure of life history strategy

Life history theory predicts that people calibrate their reproductive strategies to local levels of environmental harshness and unpredictability. While previous research has established the importance of early life cues in the development of life history strategy, the degree to which life history strategy exhibits plasticity later in life is unclear. Using longitudinal data (total N = 479) from four archival studies and a recently validated psychological measure of life history strategy, we examined mean-level trends in life history strategy at the level of psychological phenotype between the ages of 7 and 60 and found that life history strategy slowed down linearly as a function of age. Highlighting the importance of sexual selection in shaping life history strategy, we also found that men had a faster life history strategy than women at all ages and that the magnitude of this difference was constant across the lifespan. Our findings suggest that life history strategy development continues even in older adulthood. We discuss the possibility that this occurs in response to the accumulation of biological and social (e.g. offspring, relationships) capital and information about local risks and incentives.     

Rapid molecular identification of the harmful freshwater dinoflagellate <Emphasis Type="Italic">Peridinium</Emphasis> in various life stages using genus-specific single-cell PCR

Cysts of the freshwater dinoflagellate Peridinium are typically different from vegetative cells in shape and remain largely undescribed. Molecular discrimination of such cysts would be useful to a number of research disciplines. A reliable method for the amplification of ribosomal DNA (rDNA) from Peridinium at different life stages is described. This genotyping strategy relies on whole cell PCR using Peridinium-specific primers designed from available 18S rDNA sequences. Here, we demonstrate the effectiveness of Peridinium-specific PCR for the rapid molecular identification of Peridinium cells in various life stages such as vegetative, planozygote, hypnozygote and cyst.     

Cycling on the fast track: Ovulatory shifts in sexual motivation as a proximate mechanism for regulating life history strategies

In an ancestral world without modern contraception, how did women regulate their fertility? We argue that fertility may be regulated by context-dependent changes in sexual motivation that are specific to the high-fertility phase of the menstrual cycle. Accordingly, we predicted that ovulatory changes in sexual motivation would vary as a function of women's life history strategies, operationalized in terms of exposure to adverse childhood environments (high unpredictability, low SES, and low father quality). We tested this prediction in a sample of 1004 naturally cycling, pair-bonded women recruited using Amazon Mechanical Turk. Data show that women from adverse childhood backgrounds experienced higher in-pair sexual motivation and engaged in more in-pair sexual behavior at high fertility, compared to women from childhood backgrounds with low adversity. Women from low-adversity childhood backgrounds were more likely to exhibit ovulatory decreases in sexual motivation at early stages in their relationships. We found little evidence, however, that childhood environments interact with conception risk to predict women's extra-pair motivation and behavior. Results offer evidence that women may possess evolved psychological and behavioral mechanisms for regulating the timing of reproduction.     

The life history and in vivo culture of Coelomomyces utahensis (Blastocladiomycetes)

Coelomomyces utahensis is a fungal parasite of several genera of mosquitoes that inhabit rock-pools in southern Utah. Studies of the biology of Coelomomyces and their potential use in biological control of mosquitoes have been hindered by their complex life history, lack of axenic culture methods, and logistical problems producing their arthropod hosts for in vivo culture. In the case of C. utahensis, we have identified the alternate microcrustacean host as Potamocypris unicaudata, which is an ostracod that can be easily reared in abundance and stored for long periods. Described here are the life cycle and culturing of C. utahensis.     

The life history of Sulcascaris sulcata (Nematoda: Ascaridoidea), a parasite of marine molluscs and turtles

Berry G. N. and Cannon L. R. G. 1981. The life history of Sulcascaris sulcata (Nematoda: Ascaridoidea), a parasite of marine molluscs and turtles. International Journal for Parasitoiogy11: 43–54. The morphology, development and hatching of Sulcascaris sulcata eggs are described. Two moults occurred in the egg. Third stage larvae spontaneously hatched and were found to develop in marine bivalves and gastropods. Larvae grew steadily and after three to four months, when about 5 mm long, they moulted to fourth stage larvae characteristic of natural infections in bivalves from commercial catches. Experimentally, when fed to laboratory-reared Caretta caretta, the fourth stage larvae first attached at the oesophago-gastric junction where they moulted to adults in 7–21 days. Subsequent growth to mature adults was obtained by at least 5 months after infection. It is suggested that under natural conditions the life history may take up to 2 years to complete. These findings are discussed in relation to the predatory mode of feeding and the breeding habits of C. caretta and the significance of a possible health hazard to man.     

The life cycle of Gyrodinium instriatum (Dinophyceae) in culture*

The life cycle events of an unarmored dinoflagellate Gyrodinium instriatum Freudenthal et Lee has been investigated using clonal cultures. After the inoculation of vegetative cells into fresh medium, clumping of gametes was observed after a period of 10 days. In the clumps, a number of gametes were observed to be swimming in close contact with each other, pairing successively and then forming a plano-zygote. This clumping behavior is considered to be useful in the performance of sexual reproduction, particularly in the event of low cell density, because it increases the chance of fusion. Gametes of this species were most often isogarnous, although apparent amsogamous fusions were occasionally observed. When planozygotes were isolated and placed in fresh medium, they enlarged their size and finally divided into two cells. The daughter cells continued to multiply by binary fission and produced vegetative cells. Thus, G. instriatum has an alternative cycle between vegetative cells and zygotes without a hypnozygote stage. However, cysts of this species were transformed from large motile cells (pre-cyst cells) which are oblong and dorso-ventrally flattened in shape. These mottle pre-cyst cells have two longitudinal flagella, which may indicate that cysts of this species are of zygote origin. On the basis of these results, the relationship between zygotes and pre-cysts of G. instriatum is discussed. Excystment was enhanced by dark and cold treatments prior to the incubation for germination experiments with a germination success rate of 26–64%. Encystment was greatly inhibited by the lack of dark and cold treatments.     

On the life history ofTurnerella mertensiana (Rhodophyta,Gigartinales)

Turnerella (Gigartinales) withT. mertensiana known from northern Japan was studied to determine its life history. Carpospores cultured from foliose female plants gave rise on germination to crustose plants containing tetrasporangia, as noted previously inT. pennyi from the Atlantic. The crusts were slow to develop and required 3–5 years to achieve reproductive maturity. Tetraspores liberated in culturedT. mertensiana gave rise on germination eventually to thalli similar to gametophyticT. mertensiana. Thus this species may be said to adhere to the pattern of life history in which a large, foliose gametophyte alternates with a small crustose tetrasporophyte. The erect filaments of the small sporophytes branch laterally and tetrasporangial mother cells are found there, exemplifying an unusual method for crustose species to produce tetrasporangia.     

The specific identity and the life history of JapaneseSyringoderma (Syringodermatales,phaeophyceae)

Observations on JapaneseSyringoderma from Rishiri Island, which had been previously identified asS. australe, were made based on newly collected fertile material. These results and comparisons with the type specimen ofSyringoderma abyssicola (=Chlanidophora abyssicola) revealed that the Rishiri Island plants should be identified asSyringoderma abyssicola. Syringoderma abyssicola from Rishiri Island formed unilocular sporangia among the paraphyses on the fan-shaped blades in winter. The first products (uni-spores) in the unilocular sporangia form flagella, and soon after form cell walls before release. Then these reduced gametophytes divide into tetrads and form swarmers, each of which contains a chloroplast with a stigma. These swarmers germinate into branched filaments, from which thicker erect filaments of apical growth tissue. At 5–10 C these erect filaments formed fan-shaped blades under long-day conditions, and unilocular sporangia under short-day conditions corresponding respectively to spring and winter at Rishiri Island. Accordingly, the seasonal growth pattern of the species is considered to be controlled by responses to photoregime and temperature. Dedicated to the memory of the late Professor Muneao Kurogi.     

The life history of Ahnfeltiopsis paradoxa (Gigartinales, Rhodophyta) in laboratory culture

The life history of the red alga Ahnfeltiopsis paradoxa (Suringar) Masuda (Phyllophoraceae, Gigartinales) from Japan was completed in laboratory culture. Carpospores isolated from field-collected plants germinated to form circular crusts that were composed of a monostromatic hypothallium consisting of radiating filaments, a polystromatic perithallium consisting of tightly coalescent erect filaments, and hypobasal tissue derived from the hypothallium. The crusts were induced to sporulate by transferring them from short-day to long-day regimes at 15° and 2°C. Each crust produced several nemathecia along 1-4 concentric rings. Intercalary, cruciately or decussately divided tetrasporangia were formed in 4-6 (1-2 at the margin of the nemathecium) successive cells of a single filament of the nemathecia. Tetraspore germlings gave rise to basal discs from which upright axes developed. The upright axes first grew without branches or were sparsely branched and later bore many marginal reproductive proliferations. Procarps and spermatangia were formed in the proliferations on different individuals. Carposporophytes developed on female plants that were co-cultured with male plants. Gonimoblast filaments were formed from an auxiliary cell that fused with a carpogonium. Carposporangia developed from gonimoblast filaments and medullary cells contacted by the gonimoblast filaments. Carpospores were discharged through carpostomes formed in the thickened cortex. Tetraspores were cultured from field-collected crusts of a morphology similar to that of cultured tetrasporophytes. They gave rise to upright gametophytic axes similar in morphology to this species as seen in the field.     

The relative availability of inorganic carbon and inorganic nitrogen influences the response of the dinoflagellate Protoceratium reticulatum to elevated CO2

This work originates from three facts: (i) changes in CO₂ availability influence metabolic processes in algal cells; (ii) Spatial and temporal variations of nitrogen availability cause repercussions on phytoplankton physiology; (iii) Growth and cell composition are dependent on the stoichiometry of nutritional resources. In this study, we assess whether the impact of rising pCO₂ is influenced by N availability, through the impact that it would have on the C/N stoichiometry, in conditions of N sufficiency. Our experiments used the dinoflagellate Protoceratium reticulatum, which we cultured under three CO₂ regimes (400, 1,000, and 5,000 ppmv, pH of 8.1) and either variable (the NO₃^? concentration was always 2.5 mmol · L^?1) or constant (NO₃^? concentration varied to maintain the same C_i/NO₃^? ratio at all pCO₂) C_i/NO₃^? ratio. Regardless of N availability, cells had higher specific growth rates, but lower cell dry weight and C and N quotas, at elevated CO₂. The carbohydrate pool size and the C/N was unaltered in all treatments. The lipid content only decreased at high pCO₂ at constant C_i/NO₃^? ratio. In the variable C_i/NO₃^? conditions, the relative abundance of Rubisco (and other proteins) also changed; this did not occur at constant C_i/NO₃^?. Thus, the biomass quality of P. reticulatum for grazers was affected by the C_i/NO₃^? ratio in the environment and not only by the pCO₂, both with respect to the size of the main organic pools and the composition of the expressed proteome.     

How to be an invasive gammarid (Amphipoda: Gammaroidea)–comparison of life history traits

About six life history and two ecological traits of gammarid species occurring in Central European waters were compared in order to identify the characters of successful invader. The species were (1) natives: Gammarus fossarum, G. pulex, G. lacustris, G. varsoviensis, G. balcanicus, G. leopoliensis, G. roeselii, and (2) aliens: Gammarus tigrinus, Chaetogammarus ischnus (=Echinogammarus ischnus), Pontogammarus robustoides, Obesogammarus crassus, Dikerogammarus haemobaphes, D. villosus. Generally the alien species were characterised by a combination of large brood size, high partial fecundity, early maturation and by appearance of higher number of generations per year. Also, these species presented higher tolerance towards severe environmental conditions, i.e. elevated salinity and human degradation of the environment. The above features seem to facilitate the colonisation of new areas and competition with native species -- a phenomenon that has been currently observed in various parts of Europe.     

On the development and reproduction of Botryllus schlossen (Tunicata) colonies from the eastern Mediterranean Sea: plasticity of life history traits

Summary

Analysis of developmental patterns of Botryllus schlosseri colonies from the eastern Mediterranean coast has been performed on 143 genets under different temperature regimens (15,20,27 °C) for up to 22 weeks. While the average maximal size as the length of the blastogenic cycle (BC) varied in respect to water temperature, ontogeny at all temperatures was characterized by 4 developmental stages: 1. the lag phase (the first 1–3 BCs, 1 bud/BC), 2. the exponential growth phase (5.5–7.8 BCs, up to 3 buds/BC), 3. the plateau phase, (7.4–8.2 BCs, 1 bud/BC), 4. the degenerative or the variable phase. Many (40.6%) colonies were not sexually reproductive, the others were male only (30.1%) or hermaphrodites. Colonies at the peak of reproduction develop 1.2 oocytes/zooid, and up to 57.7% produced >4 clutches. Analysing onset of reproduction with maximal colony size revealed 4 patterns, two for “male only” colonies and two for hermaphrodites that varied at different sea water temperatures. In two patterns, the onset of reproduction precedes colony maximal size, and in the others it starts at the peak size or thereafter. Zooids at the colony's periphery developed almost twice as many buds as did zooids at the center, but produced significantly lower numbers of eggs. Fragmentation was recorded in large colonies and was temperature dependent. Results are compared with the data available on populations from other localities indicating for dramatically different developmental modes characteristic to this cosmopolitan species.     

Growth of the toxic dinoflagellate Alexandrium minutum (Dinophyceae) using high biomass culture systems

Toxic dinoflagellates are important in natural ecosystems and are ofglobal economic significance because of the impact of toxic blooms onaquaculture and human health. Both the organisms and the toxins they producehave potential for biotechnology applications. We investigated autotrophicgrowth of a toxic dinoflagellate, Alexandrium minutum, inthree different high biomass culture systems, assessing growth, productivityandtoxin production. The systems used were: aerated and non-aerated2-L Erlenmeyer flasks; 0.5-L glass aerated tubes; anda 4-L laboratory scale alveolar panel photobioreactor. A range ofindicators was used to assess growth in these systems. Alexandriumminutum grew well in all culture conditions investigated, with amarked increase in both biomass and productivity in response to aeration. Thehighest cell concentration (4.9 × 10⁵ cellsmL^–1) and productivity (2.6 ×10⁴cells mL^–1d^–1) was achieved inthe aerated glass culture tubes. Stable growth of A.minutum in the laboratory scale alveolar panel photobioreactor wasmaintained over a period of five months, with a maximum cell concentration of3.3 × 10⁵ cells mL^–1, a meanproductivity of 1.4 × 10⁴ cells mL^–1d^–1, and toxin production of approximately 20g L^–1 d^–1 with weeklyharvesting.     

Asexual life history by biflagellate zoids in Monostroma latissimum (Ulotrichales)

Monostroma latissimum (Kuetzing) Wittrock is a monostromatic green alga of commercial importance in Japan. Here we report the serendipitous discovery of asexually reproducing specimens collected from Usa, on the Pacific coast of Kochi Prefecture, south-western Japan. Zoids were found to be biflagellate and negatively phototactic. Germination of settled zoids was observed to follow erect-filamentous ontogeny similar to that of the previously reported sexual strain. Moreover, the newly discovered asexual strain had identical sequences of nuclear encoded ITS (Internal Transcribed Spacer) region to that of the sexual strain. On the basis of this finding, we postulate that the ITS sequences may have been maintained in these conspecific strains despite the evolution in sexuality. Relationships were investigated among M. latissimum and other monostromatic taxa within the class Ulvophyceae using ITS sequences in order to understand relative phylogenetic position of this species.     

Host-plant mediated geographic variation in the life history of Platycotis vittata (Homoptera: Membracidae)

Abstract.

• 1 The oak treehopper Platycotis vittata (Fabricius) is bivoltine throughout its range with discrete generations in the early spring and autumn. Females of both generations diapause.
• 2 Latitudinal variation in the timing of life history exists among four populations of P. vittata along the eastern coastal plain of the United States.
• 3 We disrupted synchronization between P.vittata life history and host-plant phenology in the springs of 1984 and 1985 by placing southern populations on northern trees with a different phenology. This caused some females to oviposit abnormally in late spring, without entering diapause. The offspring of these females had reduced reproductive success.
• 4 Winter diapause can be broken by providing females with a newly flushing tree with high levels of amino nitrogen in the sap. Females terminated winter diapause on trees breaking winter dormancy while females on trees still in winter dormancy did not, under identical photoperiod and temperature regimes.
• 5 The role of host-plant mediated life history variation as a process promoting intraspecific geographic differentiation in the arboreal sap-feeding guild is discussed.

     

Life history strategies and psychopathology: the faster the life strategies,the more symptoms of psychopathology

There is little extant empirical literature examining the associations between life history strategies and symptoms of psychopathology. The current study (N = 138) investigated the associations between life history strategies, symptoms of psychopathology, aggression, incidence of self-harm behaviour, and attachment (perceived parental support) in sample drawn from the general population and community mental health service providers. The results from the study indicate those with a faster life strategy report greater levels of aggression and symptoms of psychopathology. Further, perceptions of poorer parental support were associated with a faster life history strategy. Implications for life history theory, conceptualising psychopathology, and future research directions are discussed.     

Life history,excystment features,and growth characteristics of the Mediterranean harmful dinoflagellate Alexandrium pseudogonyaulax

Studies considering the biology and ecology of the toxic bloom‐forming species, Alexandrium pseudogonyaulax, are rare. Our results highlight five features not described before in A. pseudogonyaulax life cycle: (i) A. pseudogonyaulax gametes showed two modes of conjugation, anisogamy and isogamy, (ii) sexual conjugation occurs either in the dark or in the light phase by engulfment or a fusion process, (iii) the presence of planozygote and newly formed cysts in monoclonal culture suggests homothallism, (iv) newly formed cysts have very dark vesicular content and are mostly unparatabulated when observed under light microscope and (v) natural resting cysts are able to give either a planomeiocyte or two vegetative cells. Cyst viability was enhanced after 5 months of cold storage (4°C), with excystment rate reaching 97% after 3 d of incubation. Excystment rate was highest (43%–79%) in Enriched Natural Sea Water diluted culture medium, whereas few germling cells were able to survive without the culture medium (0%–13%). Salinity‐irradiance experiments revealed that the highest cell concentrations occur at high irradiances for all the tested salinities. Vegetative growth rates generally increased with increasing irradiance, and were less dependent on salinity variations. The relatively low growth rate, low cell densities in the laboratory, and the notable capacity of producing cysts along growth phases of A. pseudogonyaulax could explain the occurrence of high resting cysts densities in the sediment of Bizerte lagoon and the relatively low abundances of vegetative cells in the water column.     

Comparative phylogenetic analysis of the evolution of semelparity and life history in salmonid fishes

The selective pressures involved in the evolution of semelparity and its associated life-history traits are largely unknown. We used species-level analyses, independent contrasts, and reconstruction of ancestral states to study the evolution of body length, fecundity, egg weight, gonadosomatic index, and parity (semelparity vs. degree of iteroparity) in females of 12 species of salmonid fishes. According to both species-level analysis and independent contrasts analysis, body length was positively correlated with fecundity, egg weight, and gonadosomatic index, and semelparous species exhibited a significantly steeper slope for the regression of egg weight on body length than did iteroparous species. Percent repeat breeding (degree of iteroparity) was negatively correlated with gonadosomatic index using independent contrasts analysis. Semelparous species had significantly larger eggs by species-level analysis, and the egg weight contrast for the branch on which semelparity was inferred to have originated was significantly larger than the other egg weight contrasts, corresponding to a remarkable increase in egg weight. Reconstruction of ancestral states showed that egg weight and body length apparently increased with the origin of semelparity, but fecundity and gonadosomatic index remained more or less constant or decreased. Thus, the strong evolutionary linkages between body size, fecundity, and gonadosomatic index were broken during the transition from iteroparity to semelparity. These findings suggest that long-distance migrations, which increase adult mortality between breeding episodes, may have been necessary for the origin of semelparity in Pacific salmon, but that increased egg weight, leading to increased juvenile survivorship, was crucial in driving the transition. Our analyses support the life-history hypotheses that a lower degree of repeat breeding is linked to higher reproductive investment per breeding episode, and that semelparity evolves under a combination of relatively high juvenile survivorship and relatively low adult survivorship.     

The impact of diapause on the evolution of other life history traits in flesh flies

Summary Flesh flies (Sarcophagidae) collected in Costa Rica and Panama lack the pupal diapause that is characteristic of flesh flies from the temperate zone and tropical Africa. The absence of a diapause capacity in the neotropical species correlates with several other life history traits: in most species the post feeding wandering phase of the third larval instar is longer and duration is more variable, adult life is longer, clutch size is smaller, and more clutches are produced. Among species that have the capacity for diapause, risk is invested primarily in the diapausing stage and other life stages are brief. Though diapausing species are short-lived, they produce as many or more progeny than nondiapausing species by increasing clutch size. The slower and more variable developmental rate and increased adult longevity desynchronizes development and permits the nondiapausing species to spread an environmental risk over different stages of the life cycle, thus offering an alternative to diapause. Other traits such as body size, developmental velocity, thermal constant thresholds, thermal constants, age at first reproduction, and the interval between clutches do not appear related to the capacity for diapause.