Sex and life-history stage alter herbivore responses to a chemically defended red alga

Intraspecific variation in resistance to herbivory among genders and life-history phases of primary producers can significantly alter the ecological and evolutionary consequences of plant-herbivore interactions. Seaweeds (macroalgae) with complex life histories have multiple distinct phases with associated variation in traits that can potentially lead to differences in resistance to consumers and provide a unique system in which to simultaneously test the effects of sex and life-history stage on herbivory. We tested the susceptibility to grazing of the three life-history stages and separate sexes of the chemically defended red alga Asparagopsis armata against the sea hare Aplysia parvula, and we related this to the plant quality traits of different stages and genders. Differences in nutrient content and halogenated secondary metabolites between life-history phases were highly sex dependent. Male gametophytes had a low concentration of secondary metabolites and the highest nutrient content. The highest secondary metabolite content was found within the female gametophyte, in the wall of the reproductive structures (cystocarps) that contain the microscopic carposporophyte phase. Feeding choices by A. parvula were consistent with differences in algal quality and defense and resulted in the haploid male gametophytes being the most preferred food type. The diploid carposporophyte found inside the chemically rich cystocarps was the least consumed life-history stage. Selective herbivory of male gametophytes by A. parvula is consistent with an observed shift in gametophyte sex ratio in the field from unity at the beginning of the reproductive season to female bias at the end. The variation in susceptibility to herbivory found between sex and life-history stages of A. armata represents the first example of sex-biased consumption in seaweeds and may contribute to the maintenance of complex life histories such as those found in red algae.     

Natural dissolved humic substances increase the lifespan and promote transgenerational resistance to salt stress in the cladoceran <Emphasis Type="Italic">Moina macrocopa</Emphasis>

Purpose  

Evidence has accumulated that humic substances (HS) are not inert biogeochemicals. Rather, they cause stress symptoms and may modulate the life history of aquatic organisms. Nevertheless, it is still not clear how HS interact with additional stressors and if their effects are transgenerational. We tested the interactive effects of HS and salt to cladocerans, discussing their consequences for the persistence in fluctuating environments, such as coastal lagoons.     

Analysis of hazardous material releases due to natural hazards in the United States

Natural hazards were the cause of approximately 16,600 hazardous material (hazmat) releases reported to the National Response Center (NRC) between 1990 and 2008-three per cent of all reported hazmat releases. Rain-induced releases were most numerous (26 per cent of the total), followed by those associated with hurricanes (20 per cent), many of which resulted from major episodes in 2005 and 2008. Winds, storms or other weather-related phenomena were responsible for another 25 per cent of hazmat releases. Large releases were most frequently due to major natural disasters. For instance, hurricane-induced releases of petroleum from storage tanks account for a large fraction of the total volume of petroleum released during 'natechs' (understood here as a natural hazard and the hazardous materials release that results). Among the most commonly released chemicals were nitrogen oxides, benzene, and polychlorinated biphenyls. Three deaths, 52 injuries, and the evacuation of at least 5,000 persons were recorded as a consequence of natech events. Overall, results suggest that the number of natechs increased over the study period (1990-2008) with potential for serious human and environmental impacts.     

Does quinone or phenol enrichment of humic substances alter the primary compound from a non-algicidal to an algicidal preparation?

Dissolved organic matter (DOM) has been shown to affect phytoplankton species directly. These interactions largely depend on the origin and molecular size of DOM and are different in prokaryotes and eukaryotes. In a preceding study, however, two humic substance preparations did not adversely affect coccal green algae or cyanobacterial growth even at high concentrations of dissolved organic carbon (DOC). These results contradicted previous findings, showing a clear, negative response of different phototrophs to much lower DOC concentrations. To test whether or not at least defined building blocks of humic substances (HSs) are effective algicidal structures, we enriched two humic preparations with hydroquinone and p-benzoquinone, respectively, and exposed two different green algae, Pseudokirchneriella subcapitata and Monoraphidium braunii, and two cyanobacterial species, Synechocystis sp. and Microcystis aeruginosa, to the unmodified and enriched HSs. As response variables, growth rates in terms of biomass increase, chlorophyll-a content, and photosynthetic yield were measured. The highest concentration (4.17 mM DOC) of the modified HSs clearly inhibited growth; the cyanobacterial species were much more sensitive than the green algal species. However, realistic ecological concentrations did not adversely affect growth. Aerating the exposure solution for 24 h strongly reduced the inhibitory effect of the modified HSs. The algicidal effect was obviously caused by monomers and not by polymerised high molecular weight HSs themselves. Furthermore, the maximum quantum yield (Φ PSII max) was stimulated in the green algal species by low and medium DOC concentrations, but reduced in the cyanobacterial species upon exposure to higher HS concentrations. The quinone- and phenol-enriched HSs only showed algicidal activity at high concentrations of 4.17 mM DOC and lost their effects over time, presumably by oxidation and subsequent polymerisation. This study confirms that the applied humic substances themselves are not effective algicides even if enriched in effective structures.     

Differential Sensitivity of a Coccal Green Algal and a Cyanobacterial Species to Dissolved Natural Organic Matter (NOM) (8 pp)

Background

and Aim. In non-eutrophicated freshwaters, humic substances (HS) pose chemical stresses on aquatic organisms and, hence, separating sensitive from less sensitive or even tolerant species. One of the stresses, identified so far, is the reduction of photosynthetic oxygen production and reduction in growth in freshwater macrophytes and algae. In a previous paper, it has been shown that even closely related coccal green algae responded differently upon identical stress by HS, which is consistent with the hypothesis above. Due to their much simpler cellular ultrastructure, cyanobacteria are supposed to be more sensitive to HS exposure than eukaryote should be. One coccal green algal species (Desmodesmus communis) and one cyanobacterium (Chroococcus minutus) were exposed to four natural organic matter (NOM) isolates. One NOM has been isolated from a brown water lake (Schwarzer See) in Brandenburg State; three were obtained from a comprehensive Scandinavian NOM research project and originated from Norway (Birkenes), Finland (Hietajärvi), and Sweden (Svartberget).

Methods

Cultures of D. communis and C. minutus were obtained from the Culture Collection of Algae, Göttingen, and maintained in a common medium. The cultures were non-axenic. The algae and cyanobacteria were exposed under identical conditions to environmentally realistic NOM concentrations. Cell numbers were counted microscopically in Neugebauer cuvettes in triplicates. To avoid limitation by nutrient depletion, the experiments were terminated after 14 to 15 days. Until culture day 12, no growth limitation has been observed in the controls.

Results

All NOM isolates modulated the growth of the algae and cyanobacteria. During the early culture days, there was a slight growth promotion with the coccal green alga and to a much lesser degree with the cyanobacterium. Yet, the major effect were significant reductions in cell yield in both primary producer cultures. C. minutus was much more affected than D. communis. This applies particularly to the three tested Scandinavian NOM isolates, which were effective at concentrations even below 1 mg L-1 DOC.

Discussion

The growth promoting effect may be due to an increase in bioavailability of some trace nutrients in the presence of NOM, the release of some growth promoting substances by microbial or photochemical processing of the NOM, and/or a hormetic effect. The growth reducing effect can be explained as a herbicide-like mode of action that affects the photosystem II most prevalent by blocking the electron transport chain, absorption of electrons, or production of an internal oxidative stress after processing the bioconcentrated HS. Furthermore, it may be postulated that also photo-toxicity of these HS in the algal cells contributes to the overall toxicity; however, experimental evidence is lacking so far.

Conclusions

Upon exposure to HS, cyanobacteria appear to be much more sensitive than coccal green algae and respond in growth reduction. This high sensitivity of cyanobacteria to HS may explain phytoplankton patterns in the field. Eutrophic, humic-rich lakes do not support the cyanobacterial blooms characteristic of eutrophic, but humic-poor lakes. In the humic-rich systems, raphidophytes or, less frequent, specific coccal greens are more common. Obviously, cyanobacteria appear to be unable to make advantage of their accessory pigments (phycocyanin) to exploit the reddish light prevailing in humic-rich lakes.

Recommendation

. At present, no effective structure can be figured out which may be responsible for the adverse effect on the cyanobacterial species. It is reserved to future research whether or not HS may be applied more specifically (for instance, with elevated moieties of the effective structures) as a natural geochemical to combat cyanobacterial blooms.

     

Prenatal diagnosis of trisomy 20 by chorionic villus sampling (CVS): a case report with long-term outcome

A case of prenatally diagnosed non-mosaic trisomy 20 in cells cultured from a chorionic villus sample (CVS)is presented. The term placental karyotype was also non-mosaic trisomy 20. The karyotype of thenewborn was 46,XY/47,XY,+20 in foreskin cultures and in a second skin culture; blood lymphocyte culture was 46,XY. Aside from diffuse, hypopigmentary swirls along the lines of Blaschko observed on hisextremities and trunk, referred to as hypomelanosis of Ito, the patient is clinically normal at 8¾ years ofage. In addition, he is one of the oldest reported cases of mosaic trisomy 20 confirmed after birth forwhich the clinical outcome has been monitored. This case demonstrates that these trisomy 20 findings are compatible with normal psychomotor development and phenotype. Copyright © 2001 John Wiley & Sons, Ltd.     

Influence of mechanical-biological waste pre-treatment methods on the gas formation in landfills

In order to minimise emissions and environmental impacts, only pre-treated waste should be disposed of. For the last six years, a series of continuous experiments has been conducted at the Institute WAR, TU Darmstadt, in order to determine the emissions from pre-treated waste. Different kinds of pre-treated waste were incubated in several reactors and various data, including production and composition of the gas and the leachate, were collected. In this paper, the interim results of gas production and the gas composition from different types of waste after a running time of six years are presented and discussed.     

Measurement of odour with focus on sampling techniques

The treatment of waste and many manufacturing processes cause odour emissions. In order to prevent odours, the residents and businesses in the neighbourhood of such plants complain about odour, and it becomes necessary to reduce the emissions. To achieve that, the emissions have to be investigated and evaluated in a representative and reproducible manner. The DIN EN 13725 (2003) [DIN EN 13725. 2003. Luftbeschaffenheit--Bestimmung der Geruchsstoffkonzentration mit dynamischer Olfaktometrie--Air quality--Determination of odour concentration by dynamic olfactometry, Deutsche Fassung EN 13725:2003. Beuth Verlag, Berlin (DE)] provides a European standard for the measurement of odour. Nevertheless, the subject of sampling is not standardised; even though it has a substantial influence on the results of the measurements. In this paper, the odour measurement itself, as well as the different kinds of sampling methods (depending on the specific type of source), will be presented and discussed.