Elysia timida (Risso, 1818) three decades of research

During the last 30 years, studies on Elysia timida (Risso, 1818) have addressed various aspects related to food sources, photosynthetic efficiency of kleptoplasts, population genetics, chemical ecology and reproductive biology, both in the Mediterranean Sea and in the Mar Menor coastal lagoon. E. timida shows a strong specific interaction with Acetabularia acetabulum, retaining functional chloroplasts for at least 45 days and obtaining extra energy in periods when food resources are scarce. It shows control of parapodia, avoiding pigment photodestruction under oversaturated light conditions. The chemical ecological relationships established between E. timida and its potential predator fish, Thalassoma pavo, have also been evaluated, and it has been found that that the extracts of the mollusc contain repellent and unpalatable polypropionate compounds. Population genetics has demonstrated the genetic divergence between populations showing high and significant values of FST and genetic distances, and at least six privative alleles that are not shared with Mediterranean populations have been detected in lagoon populations. This sacoglossan is a poecilogonic species, and its lagoon populations show a greater reproductive output than Mediterranean populations; they produce a greater number of egg masses and embyros per individual, and the capsules have a wider diameter.

Colour morphotypes of Elysia timida (Sacoglossa, Gastropoda) are determined by light acclimation in food algae

Elysia timida (Risso, 1818) colonizing the shallow waters of the Mar Menor Lagoon (Spain) exhibit a brown and a green morph. It was hypothesised that these morphs were the result of feeding preferentially on brown and green algae, respectively. E. timida and its potential food sources, Acetabularia acetabulum (Chlorophyta) and Halopteris filicina (Heterokontophyta) were collected by snorkelling during April 2010. Photosynthetic pigments were analysed by HPLC, photo-physiological parameters were estimated by PAM fluorometry and body colour was characterized by spectral reflectance. Digital photography was used to count the number and area of red spots (small red dots on the slug’s surface) on the parapodia of the 2 morphs. In the laboratory, green E. timida was fed with A. acetabulum cultured under 2 light treatments (high light, 600 µmol E m−2 s−1 and low light, 40 µmol E m−2 s−1), and digital photography was used to monitor colour alterations in E. timida. Spectral reflectance confirmed the colour differences, but both morphs showed a pigment composition similar to the green alga A. acetabulum and showed none of the pigments present in the brown alga H. filicina, neither immediately after collection of the slugs in situ, nor after the feeding experiment. A. acetabulum grown under high light intensity changed from green to brown colour and E. timida changed to brown colour when fed with high-light acclimated A. acetabulum. Thus, E. timida colour differences could not be attributed to feeding on different algae groups but was likely the result of feeding on A. acetabulum growing under different light intensities.

Elysia timida (Risso, 1818) three decades of research

Elysia timida (Risso, 1818) three decades of research.— During the last 30 years, studies on Elysia timida (Risso, 1818) have addressed various aspects related to food sources, photosynthetic efficiency of kleptoplasts, population genetics, chemical ecology and reproductive biology, both in the Mediterranean Sea and in the Mar Menor coastal lagoon. E. timida shows a strong specific interaction with Acetabularia acetabulum, retaining functional chloroplasts for at least 45 days and obtaining extra energy in periods when food resources are scarce. It shows control of parapodia, avoiding pigment photodestruction under oversaturated light conditions. The chemical ecological relationships established between E. timida and its potential predator fish, Thalassoma pavo, have also been evaluated, and it has been found that that the extracts of the mollusc contain repellent and unpalatable polypropionate compounds. Population genetics has demonstrated the genetic divergence between populations showing high and significant values of FST and genetic distances, and at least six privative alleles that are not shared with Mediterranean populations have been detected in lagoon populations. This sacoglossan is a poecilogonic species, and its lagoon populations show a greater reproductive output than Mediterranean populations; they produce a greater number of egg masses and embyros per individual, and the capsules have a wider diameter.

Chloroplast genes are expressed during intracellular symbiotic association of Vaucheria litorea plastids with the sea slug Elysia chlorotica.

The marine slug Elysia chlorotica (Gould) forms an intracellular symbiosis with photosynthetically active chloroplasts from the chromophytic alga Vaucheria litorea (C. Agardh). This symbiotic association was characterized over a period of 8 months during which E. chlorotica was deprived of V. litorea but provided with light and CO2. The fine structure of the symbiotic chloroplasts remained intact in E. chlorotica even after 8 months of starvation as revealed by electron microscopy. Southern blot analysis of total DNA from E. chlorotica indicated that algal genes, i.e., rbcL, rbcS, psaB, psbA, and 16S rRNA are present in the animal. These genes are typically localized to the plastid genome in higher plants and algae except rbcS, which is nuclear-encoded in higher plants and green (chlorophyll a/b) algae. Our analysis suggests, however, that similar to the few other chromophytes (chlorophyll a/c) examined, rbcS is chloroplast encoded in V. litorea. Levels of psbA transcripts remained constant in E. chlorotica starved for 2 and 3 months and then gradually declined over the next 5 months corresponding with senescence of the animal in culture and in nature. The RNA synthesis inhibitor 6-methylpurine reduced the accumulation of psbA transcripts confirming active transcription. In contrast to psbA, levels of 16S rRNA transcripts remained constant throughout the starvation period. The levels of the photosystem II proteins, D1 and CP43, were high at 2 and 4 months of starvation and remained constant at a lower steady-state level after 6 months. In contrast, D2 protein levels, although high at 2 and 4 months, were very low at all other periods of starvation. At 8 months, de novo synthesis of several thylakoid membrane-enriched proteins, including D1, still occurred. To our knowledge, these results represent the first molecular evidence for active transcription and translation of algal chloroplast genes in an animal host and are discussed in relation to the endosymbiotic theory of eukaryote origins.

El Alphonso o La Fundación del Reino de Portugal, assegurada y perfecta en la conquista de Elysia /

Mode of access: Internet.

El Alphonso o La fundación del Reyno de Portugal, asegurada y perfecta en la conquista de Elysia : poema épico /

Mode of access: Internet.

南亚和东南亚龙胆属(龙胆科)的新名称、新组合及分类注释(英文)

本文提出了龙胆属两个种的新名称 (GentianamembranuliferaT .N .Ho,G .nudicaulis Kurz var.as samensisT .N .Ho )和 5个变种的新组合 [(Gentianalateriflora Hemsl.var.uncifolia (H.J.Lam)T.N.Ho,G.sumatranaRidl.var.humifusa (S .Moore)T .N .Ho ,G .quadrifariaBl.var.wightii(Kusnez.)T .N .Ho,G .loerzingiiRidl.var.timida (Kerr)T .N .Ho ,G .membranuliferaT .N .Hovar.recurvata (Kusnez.)T .N .Ho) ]。

Score for neonatal acute physiology-II and neonatal pain predict corticospinal tract development in premature newborns

Premature infants are at risk for adverse motor outcomes, including cerebral palsy and developmental coordination disorder. The purpose of this study was to examine the relationship of antenatal, perinatal, and postnatal risk factors for abnormal development of the corticospinal tract, the major voluntary motor pathway, during the neonatal period. In a prospective cohort study, 126 premature neonates (24-32 weeks' gestational age) underwent serial brain imaging near birth and at term-equivalent age. With diffusion tensor tractography, mean diffusivity and fractional anisotropy of the corticospinal tract were measured to reflect microstructural development. Generalized estimating equation models examined associations of risk factors on corticospinal tract development. The perinatal risk factor of greater early illness severity (as measured by the Score for Neonatal Acute Physiology-II [SNAP-II]) was associated with a slower rise in fractional anisotropy of the corticospinal tract (P = 0.02), even after correcting for gestational age at birth and postnatal risk factors (P = 0.009). Consistent with previous findings, neonatal pain adjusted for morphine and postnatal infection were also associated with a slower rise in fractional anisotropy of the corticospinal tract (P = 0.03 and 0.02, respectively). Lessening illness severity in the first hours of life might offer potential to improve motor pathway development in premature newborns.

Tractography-based quantitation of corticospinal tract development in premature newborns

To evaluate the impact of early brain injury and neonatal illness on corticospinal tract (CST) development in premature newborns serially studied with diffusion tensor tractography.

Educação de jovens e adultos: subsídios à construção da cidadania

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Mid-Pleistocene benthic foraminiferal record in the Southwest Pacific

Benthic foraminiferal faunas from three bathyal sequences provide a proxy record of oceanographic changes through the mid-Pleistocene transition (MPT) on either side of the Subtropical Front (STF), east of New Zealand. Canonical correspondence analyses show that factors related to water depth, latitude and climate cycles were more significant than oceanographic factors in determining changes in faunal assemblage composition over the last 1 Ma. Even so, mid-Pleistocene faunal changes are recognizable and can be linked to inferred palaeoceanographic causes. North of the largely stationary STF the faunas were less variable than to the south, perhaps reflecting the less extreme glacial-interglacial fluctuations in the overlying Subtropical Surface Water. Prior to Marine Isotope Stage (MIS) 21 and after MIS 15, the northern faunas had fairly constant composition, but during most of the MPT faunal composition fluctuated in response to climate-related food-supply variations. Faunal changes through the MPT suggest increasing food supply and decreasing dissolved bottom oxygen. South of the STF, beneath Subantarctic Surface Water, mid-Pleistocene faunas exhibited strong glacial-interglacial fluctuations, inferred to be due to higher interglacial nutrient supply and lower oxygen levels. The most dramatic faunal change in the south occurred at the end of the MPT (MIS 17- 12). with an acme of Abditodentrix pseudothalmanni, possibly reflecting higher carbon flux and lower bottom oxygen. This study suggests that the mid-Pleistocene decline and extinction of a group of elongate, cylindrical deep-sea foraminifera may have been related to decreased bottom oxygen concentrations as aresult of slower deep-water currents.

Distribution of deep-sea foraminifera in surface sediments east of New Zealand

Paleobathymetric assessments of fossil foraminiferal faunas play a significant role in the analysis of the paleogeographic, sedimentary, and tectonic histories of New Zealand's Neogene marine sedimentary basins. At depths >100 m, these assessments often have large uncertainties. This study, aimed at improving the precision of paleodepth assessments, documents the present-day distribution of deep-sea foraminifera (>63 µm) in 66 samples of seafloor sediment at 90-700 m water depth (outer shelf to mid-abyssal), east of New Zealand. One hundred and thirty-nine of the 465 recorded species of benthic foraminifera are new records for the New Zealand region. Characters of the foraminiferal faunas which appear to provide the most useful information for estimating paleobathymetry are, in decreasing order of reliability: relative abundance of common benthic species; benthic species associations; upper depth limits of key benthic species; and relative abundance of planktic foraminifera. R mode cluster analysis on the quantitative census data of the 58 most abundant species of benthic foraminifera produced six species associations within three higher level clusters: (1) calcareous species most abundant at mid-bathyal to outer shelf depths (<1000 m); (2) calcareous species most abundant at mid-bathyal and greater depths (>600 m); (3) agglutinated species mostly occurring at deep abyssal depths (>3000 m). A detrended correspondence analysis ordination plot exhibits a strong relationship between these species associations and bathymetry. This is manifest in the bathymetric ranges of the relative abundance peaks of many of the common benthic species (e.g., Abditodentrix pseudothalmanni 500-2800 m, Bolivina robusta 200-650 m, Bulimina marginata f. marginata 20-600 m, B. marginata f. aculeata 400-3000 m, Cassidulina norvangi 1000-4500 m, Epistominella exigua 1000-4700 m, and Trifarina angulosa 10-650 m), which should prove useful in paleobathymetric estimates. The upper depth limits of 28 benthic foraminiferal species (e.g., Fursenkoina complanata 200 m, Bulimina truncana 450 m, Melonis affinis 550 m, Eggerella bradyi 750 m, and Cassidulina norvangi 1000 m) have potential to improve the precision of paleobathymetric estimates based initially on the total faunal composition. The planktic percentage of foraminiferal tests increases from outer shelf to upper abyssal depths followed by a rapid decline within the foraminiferal lysocline (below c. 3600 m). A planktic percentage <50% is suggestive of shelf depths, and >50% is suggestive of bathyal or abyssal depths above the CCD. In the abyssal zone there is dramatic taphonomic loss of most agglutinated tests (except some textulariids) at burial depths of 0.1-0.2 m, which negates the potential usefulness of these taxa in paleobathymetric assessments.

Late Quaternary benthic foraminiferal record of the Bounty Trough, east of New Zealand

The Bounty Trough, east of New Zealand, lies along the southeastern edge of the present-day Subtropical Front (STF), and is a major conduit via the Bounty Channel, for terrigenous sediment supply from the uplifted Southern Alps to the abyssal Bounty Fan. Census data on 65 benthic foraminiferal faunas (>63 µm) from upper bathyal (ODP 1119), lower bathyal (DSDP 594) and abyssal (ODP 1122) sequences, test and refine existing models for the paleoceanographic and sedimentary history of the trough through the last 150 ka (marine isotope stages, MIS 6-1). Cluster analysis allows recognition of six species groups, whose distribution patterns coincide with bathymetry, the climate cycles and displaced turbidite beds. Detrended canonical correspondence analysis and comparisons with modern faunal patterns suggest that the groups are most strongly influenced by food supply (organic carbon flux), and to a lesser extent by bottom water oxygen and factors relating to sediment type. Major faunal changes at upper bathyal depths (1119) probably resulted from cycles of counter-intuitive seaward-landward migrations of the Southland Front (SF) (north-south sector of the STF). Benthic foraminiferal changes suggest that lower nutrient, cool Subantarctic Surface Water (SAW) was overhead in warm intervals, and higher nutrient-bearing, warm neritic Subtropical Surface Water (STW) was overhead in cold intervals. At lower bathyal depths (594), foraminiferal changes indicate increased glacial productivity and lowered bottom oxygen, attributed to increased upwelling and inflow of cold, nutrient-rich, Antarctic Intermediate Water (AAIW) and shallowing of the oxygen-minimum zone (upper Circum Polar Deep Water, CPDW). The observed cyclical benthic foraminiferal changes are not a result of associations migrating up and down the slope, as glacial faunas (dominated by Globocassidulina canalisuturata and Eilohedra levicula at upper and lower bathyal depths, respectively) are markedly different from those currently living in the Bounty Trough. On the abyssal Bounty Fan (1122), faunal changes correlate most strongly with grain size, and are attributed to varying amounts of mixing of displaced and in-situ faunas. Most of the displaced foraminifera in turbiditic sand beds are sourced from mid-outer shelf depths at the head of the Bounty Channel. Turbidity currents were more prevalent during, but not restricted to, glacial intervals.