Effects of NaCl stress on seed germination and seedling development of Brassica insularis Moris (Brassicaceae)

• Brassica insularis is a protected plant that grows on both coastal and inland cliffs in the western Mediterranean Basin. The objective of this study was to test if any variability exists in the salt stress response during seed germination and seedling development in this species relative to its provenance habitat.
• Variability among three populations in the salt stress effects on seed germination and recovery under different temperatures was evaluated. The effect of nebulisation of a salt solution on seedling development was evaluated between populations growing at different distances from the sea.
• Seeds of B. insularis could germinate at NaCl concentrations up to 200 mm . Seed viability was negatively affected by salt, and recovery ability decreased with increasing temperature or salinity. Inter‐population variability was detected in salt response during the seed germination phase, as well as in seedling salt spray tolerance. The inland population seedlings had drastically decreased survival and life span and failed to survive to the end of the experiment. In contrast, at least 90% of the coastal seedlings survived, even when sprayed at the highest frequency with salt solution.
• This study allowed investigation of two natural factors, soil salinity and marine aerosols, widely present in the B. insularis habitat, and provided the first insights into ecology of this protected species and its distribution in the Mediterranean. These results might be useful in understanding the actual distributions of other species with the same ecology that experience these same abiotic parameters.

     

Early-life density-dependence effects on growth and survival in subantarctic fur seals

Understanding the regulation of natural populations has been a long-standing research program in ecology. Current knowledge on marine mammals and seabirds is biased toward the adult component of populations and lacking are studies investigating the juvenile component. Our goal was to estimate demographic parameters on the pre-weaning stage of a subantarctic fur seal (Arctocephalus tropicalis) population on Amsterdam Island, suspected to be regulated by density-dependence. The influence of abundance on growth parameters (length and weight) and survival was assessed over a study period spanning 16 years. We evidenced a negative trend in population growth rate when density increased. Density-dependence models were favored for pup body size and mass growth. Abundance had a clear influence on body length at high population-density, pups grew slower and were smaller at weaning than pups born in years with low population density. Abundance partly explained pup body mass variation and a weak effect was detected on pre-weaning survival. The causal mechanisms may be increased competition for food resources between breeding females, leading to a reduction of maternal input to their pups. Our results suggested that pup favored survival over growth and the development of their diving abilities in order to withstand the extreme fasting periods that are characteristic of this fur seal population. This analysis provides significant insight of density-dependent processes on early-life demographic parameters of a long lived and top-predator species, and more specifically on the pre-weaning stage with important consequences for our understanding of individual long-term fitness and population dynamics.     

Marine fragrance chemistry

The main marine message in perfumery is projected by Calone 1951 (7-methyl-2H-1,5-benzodioxepin-3(4H)-one). Kraft (Givaudan) and Gaudin (Firmenich) further maximized the marine fragrance molecular membership by extending the carbon chain of the 7-Me group. Our research targeted the polar group of the benzodioxepinone parent compound to investigate how this region of molecular makeup resonates with the dominant marine fragrance of the Calone 1951 structure. The olfactory evaluation of analogues prepared by chemical modification or removal of the CO group resulted in the introduction of aldehydic, sweet and floral-fruity notes with a diluted/diminished potency of the marine odor. To further analyze the olfactory properties of benzodioxepinones containing a diverse range of aromatic ring substituents, a novel synthesis route was developed. We found that a 7-alkyl group in Calone 1951 was essential for the maintenance of the significant marine odor characteristic, and our studies support the concept that the odorant structure occupying the hydrophobic binding pocket adjacent to the aromatic ring-binding site of the olfactory receptor is pivotal in the design and discovery of more potent and characteristic marine fragrances. How the structure of benzodioxepinones connects to marine sea-breeze fragrances is our continuing challenging research focus at the chemistry-biology interface.     

New trends in phospholipid class composition of marine sponges

The exceptional ability of marine sponges to adapt to often drastic changes of their environments could be due to special structural features in cell membranes, including firstly phospholipids (PL). Thus, PL class composition was investigated in marine sponges (22 species from 19 genera to 15 families) originating from various locations (East Atlantic, North Atlantic, South-West Pacific, Mediterranean Sea, Red Sea, Arabian–Persian Gulf). The quantitative determination of PL class composition was obtained by high-performance thin-layer chromatography (HPTLC) with scanning densitometry of the different spots. Previous reports have shown phosphatidylethanolamine (PE) as the major PL class in marine sponges, followed by phosphatidylcholine (PC), while other papers described PC as a minor class and even lacking. This survey found PE as the major PL class in only two species, while PC was the major class in 13 species including a calcareous one. The great abundance of bacteria in some sponges was evidenced from the relatively high proportions of particular PL classes. Various PL distributions were observed even for the sponge species collected in the same area and belonging to the same genus. Thus, no clear rule on PL composition in marine sponges can be stated to date.     

Rediscovery and redescription of the marine peritrichous ciliate Epicarchesium abrae (Precht, 1935) nov. comb. (Protozoa, Ciliophora, Peritrichia)

The morphology, infraciliature and silverline system of the marine peritrichous ciliate, Epicarchesium abrae (Precht, 1935) nov. comb., isolated from an abalone-farming pond off the coast of Qingdao, China, are investigated. E. abrae is characterized by: size of zooid in vivo 68 μm×48 μm on average; macronucleus usually J-shaped; one dorsally-located contractile-vacuole; colony regularly dichotomously branched with 4–16 zooids; total number of transverse silverlines 62–72, from peristome to aboral ciliary wreath 41–47, from aboral ciliary wreath to scopula 21–25; outer kinety of peniculus 3 prolonged and converges with peniculus 1.     

New observations on the tontoniid ciliate Spirotontonia grandis (Suzuki and Han, 2000) Agatha, 2004 (Ciliophora, Oligotrichida, Tontoniidae); comparison with the similar Laboea strobila

Spirotontonia grandis (Suzuki and Han, 2000) Agatha, 2004 belongs to the family Tontoniidae Agatha, 2004 because it has a contractile tail. It is the type of the genus Spirotontonia Agatha, 2004, which is characterized by a sinistrally spiralled girdle kinety. Supplementary observations on protargol-impregnated and, especially, live specimens of S. grandis from the Irish Sea are provided. These new findings are included in an improved species diagnosis. Furthermore, they contribute to a better separation of the tontoniid S. grandis from the strombidiid Laboea strobila, which also has a screw-like appearance, a sinistrally spiralled girdle kinety, and multiple macronuclear nodules, but lacks the tontoniid tail. Since the tail of S. grandis, the main distinguishing feature between the two species, is highly contractile and easily lost, further differences are emphasized, e.g., the lower number of girdle kinety whorls (3.0–3.5 vs. 4.5–5.0), the larger cell size (110–170×55–80 μm vs. 80–110×40–60 μm after protargol impregnation), the relatively larger size of the ventral portion of the membranellar zone (51% vs. 40% of body length), and the overlapping cortical platelets (present vs. absent). The record of S. grandis from the Irish Sea is the first record outside the East China Sea and the second worldwide.     

Antifouling enzymes and the biochemistry of marine settlement

Antifouling coatings are used extensively on marine vessels and constructions, but unfortunately they are found to pose a threat to the marine environment, notably due to content of metal-based biocides. Enzymes have repeatedly been proposed as an alternative to traditional antifouling compounds. In this review, the enzymes claimed to hold antifouling activity are classified according to catalytic functions. The enzyme functions are juxtaposed with the current knowledge about the chemistry of settlement and adhesion of fouling organisms. Specific focus will be on bacteria, microalgae, invertebrate larvae and macroalgae zoospores. Two main concepts in enzyme-based antifouling are identified: breakdown of adhesive components and catalytic production of repellent compounds in-situ. The validity of the various modes of action is evaluated and the groups of enzymes with the highest potential are highlighted.     

Isolation and characterization of Candida membranifaciens subsp. flavinogenie W14-3, a novel riboflavin-producing marine yeast

We found that the marine yeast strain W14-3 isolated from seawater of China Eastern Sea could produce riboflavin. It is interesting to observe that the marine yeast strain produced a large amount of riboflavin in the medium containing xylose, sucrose, galactose and maltose under the conditions of vigorous shaking. The yeast strain was found to belong to Candida membranifaciens subsp. flavinogenie based on the results of routine and molecular identification. The protein sequences deduced from the partial genes encoding GTP cyclohydrolase II and 3,4-dihydroxy-2-butanone-4-phosphate synthase in the yeast exhibited high identity with those of the corresponding enzymes for riboflavin biosynthesis in other yeasts. Fe³⁺ available in the medium repressed riboflavin production and expression of the genes responsible for riboflavin biosynthesis in the yeast. The results have evidenced that a riboflavin synthesis pathway indeed existed in the yeast. This is the first study to report that C. membranifaciens subsp. flavinogenie W14-3 from the marine environment could produce riboflavin.     

Taxonomy, molecular phylogeny, and ultrastructural morphology of Olpidiopsis porphyrae sp. nov. (Oomycetes, straminipiles), a unicellular obligate endoparasite of Bangia and Porphyra spp. (Bangiales, Rhodophyta)

Olpidiopsis porphyrae sp. nov., a marine oomycete endoparasite that infects the commercially cultivated red alga Porphyra yezoensis, is described and its phylogenetic position based on molecular data and ultrastructural morphology is discussed. O. porphyrae infects the host Porphyra by means of encysted zoospores. Spherical-shaped holocarpic thalli develop within the cytoplasm of its algal host, which produce monoplanetic, subapically biflagellate zoospores. The characteristic features of this isolate are the ellipsoidal, unicellular thallus and simple holocarpic zoosporangial development, which show morphological similarity with the genus Olpidiopsis. Laboratory infection experiments with a wide range of green, brown, and red algae revealed that O. porphyrae infects several stages of the bangialean red algae (the genera Bangia and Porphyra). Molecular phylogenetic analyses inferred from both SSU rRNA and cox2 genes showed O. porphyrae branched before the main saprolegnian and peronosporalean lineages within the monophyletic oomycete clade, indicating its phylogenetic separation from them. A single or double K-body-like organelle, which contains tubular inclusions, is found located to one side of the zoospore nucleus and shows similarities to homologous organelles previously described in O. saprolegniae. The ultrastructural morphology of O. porphyrae with zoospore initials containing K-bodies and tubular mitochondrial cristae is characteristic of oomycetes. Group I intron-like multiple insertions were found in the SSU rRNA gene of O. porphyrae. This is the first report of SSU group I introns in the class Oomycetes.     

拟伍氏游仆虫(原生动物,纤毛门,游仆目)的重描述

利用活体观察和银染技术,对采自广东省惠阳大亚湾沿岸的一种罕见海洋游仆类纤毛虫拟伍氏游仆虫Euplotes parawoodruffi进行了再研究,补充了有关活体形态学、性状变异以及分类学特征的统计学资料等。中国新纪录种拟伍氏游仆虫大亚湾种群与原报道种群存在细微差异,其主要特征为:口围带小膜数为60~70;体纤毛器数目及排布模式十分稳定:额腹棘毛9根,横棘毛5根,尾棘毛2根,左缘棘毛2根;背触毛恒为9列;大核近T形,形状多变。