Mortality, protoplasm decay rate, and reliability of staining techniques to recognise 'living' foraminifera: a review.

Non-vital staining, especially with rose Bengal, has been widely used in ecological studies to differentiate between the tests of dead(unstained) foraminifera from those presumed to be living at the time of collection (stained). Doubts have been expressed about staining methods because of the possibility that dead individuals may retain undecayed protoplasm for weeks or months after death; when stained, such individuals would be recorded as living. To assess the importance of such false positives, it is necessary to examine rates of mortality, and the modes of generation of empty tests, i.e., whether due to reproduction, growth stages (leaving empty tests during growth) or death. It can be argued that reproduction, ontogeny, and death through predation lead to tests devoid of protoplasm. Whereas reproduction may affect only a small proportion of the population of each species (due to high pre-reproductive mortality), predation in oxygenated environments may be responsible for the major part of that pre-reproductive mortality. In oxygenated environments, disease or adverse environmental conditions are most likely to lead to dead individuals having tests containing protoplasm. In dysaerobic/anoxic environments, predation by macrofauna may be excluded, so foraminifera die through other causes and thus more tests with dead protoplasm may be potentially available for staining. Therefore, for most other environments, the problem of staining dead individuals is almost certainly overstated. Furthermore, from comparative studies, it seems that the most commonly used technique (staining with rose Bengal) is as reliable as others. Now that new vital staining techniques, especially the use of fluorescent probes, are being introduced, it is timely for further objective comparative studies of all techniques to be made in order to evaluate data already gathered and to develop the best strategies for future ecological studies according to whether they are field-based or experimental

Rethinking the test: functional and evolutionary implications

Abstrac

Concept of Formation Length in Radiation Theory

The features of electromagnetic processes are considered which connected with finite size of space region in which final particles (photon, electron-positron pair) are formed. The longitudinal dimension of the region is known as the formation length. If some external agent is acting on an electron while traveling this distance the emission process can be disrupted. There are different agents: multiple scattering of projectile, polarization of a medium, action of external fields, etc. The theory of radiation under influence of the multiple scattering, the Landau-Pomeranchuk-Migdal (LPM) effect, is presented. The probability of radiation is calculated with an accuracy up to "next to leading logarithm" and with the Coulomb corrections taken into account. The integral characteristics of bremsstrahlung are given, it is shown that the effective radiation length increases due to the LPM effect at high energy. The LPM effect for pair creation is also presented. The multiple scattering influences also on radiative corrections in a medium (and an external field too) including the anomalous magnetic moment of an electron and the polarization tensor as well as coherent scattering of a photon in a Coulomb field. The polarization of a medium alters the radiation probability in soft part of spectrum. Specific features of radiation from a target of finite thickness include: the boundary photon emission, interference effects for thin target, multi-photon radiation. The experimental study of LPM effect is described. For electron-positron colliding beams following items are discussed: the separation of coherent and incoherent mechanisms of radiation, the beam-size effect in bremsstrahlung, coherent radiation and mechanisms of electron-positron creation.Comment: Revised review paper, 96 pages, 28 figures. Description of SLAC E-146 experiment removed, discussion of CERN SPS experiment adde

Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV

Results are presented from a search for a W' boson using a dataset corresponding to 5.0 inverse femtobarns of integrated luminosity collected during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV. The W' boson is modeled as a heavy W boson, but different scenarios for the couplings to fermions are considered, involving both left-handed and right-handed chiral projections of the fermions, as well as an arbitrary mixture of the two. The search is performed in the decay channel W' to t b, leading to a final state signature with a single lepton (e, mu), missing transverse energy, and jets, at least one of which is tagged as a b-jet. A W' boson that couples to fermions with the same coupling constant as the W, but to the right-handed rather than left-handed chiral projections, is excluded for masses below 1.85 TeV at the 95% confidence level. For the first time using LHC data, constraints on the W' gauge coupling for a set of left- and right-handed coupling combinations have been placed. These results represent a significant improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe

Ecology and nutrition of the large agglutinated foraminiferan Bathysiphon capillare in the bathyal NE Atlantic: distribution within the sediment profile and lipid biomarker composition

The large agglutinated foraminiferan Bathysiphon capillare de Folin (Protista) was an important component of the macrofauna in box core samples recovered at a 950 m site on the southern flank of the Wyville-Thomson Ridge, northern Rockall Trough. The long, narrow, very smooth, flexible tubes of B. capillare reached a maximum length of almost 10 cm. Densities ranged from 100 to 172 ind. m-2, a figure that represents at least 5 to 9% of metazoan macrofaunal densities. This infaunal species usually adopted a more or less horizontal orientation within the upper 5 cm layer of brownish sandy silt. Its cytoplasm yielded a diverse spectrum of fatty acids. These included various monounsaturated fatty acids (39% of total), mainly 18:1(n-7), 20:1(n-9) and 22:1(n-7), the polyunsaturated fatty acids (PUFA) 20:4(n-6), 20.5(n-3) and 22.6(n-3), and non-methylene diene-interrupted fatty acids (NMIDS), particularly 22:2[delta]7,13 and 22:2[delta]7,15. The spectrum of PUFAs is consistent with the ingestion by B. capillare of phytodetrital material. However, the presence of NMIDS, reported here for the first time in a protist, provides evidence for a substantial bacterial component in the diet. Viewed by scanning electron microscopy (SEM), the cytoplasm occupied a narrow space between the inner organic test lining and an inner core of detritus around which it formed a sheath. The core material included numerous spherical structures (2 to 10 µm diameter) that we interpret as stercomata (waste pellets composed largely of mineral grains). Taken together, our observations suggest that B. capillare is a deposit feeder, consuming sediment, detritus and associated bacteria. Other deep infaunal foraminiferans probably have a similar diet, leading us to speculate that these protists, which are often abundant in dysoxic settings, may contribute significantly to carbon cycling in the deep sea. Since B. capillare and similar large Bathysiphon species can be recovered in good condition from bathyal depths, they may prove to be ideal experimental subjects for addressing some fundamental issues in the lipid biochemistry of deep-sea benthic organisms

A note on the genetic similarity between shallow- and deep-water Epistominella vitrea (Foraminifera) in the Antarctic

Many Antarctic species are known to have large bathymetric ranges. However, little is known about the genetic diversity of populations living at different depths. In certain microfauna- and meiofauna-sized taxa, some morphospecies can be divided into several cryptic genetic species. To test whether cryptic diversity is linked with depth of occurrence in Southern Ocean foraminifera, we compared ribosomal DNA sequences of selected calcareous foraminiferal species from shallow localities in McMurdo Sound and deep ones in the Weddell Sea. We found that at least one species, Epistominella vitrea, was genetically almost identical between the two localities, having a bathymetric range of over 1000 m. Our study provides molecular evidence for an extraordinarily large depth migration of Antarctic shelf foraminifera. It also suggests a relationship between populations of foraminifera from widely separated geographic regions of the Southern Ocean

A large testate protist, Gromia sphaerica sp.nov. (Order Filosea), from the bathyal Arabian Sea

The deep ocean provides a habitat for several large testate protistan taxa, e.g., xenophyophores and komokiaceans. However, testate amoebae (orders Lobosea and Filosea) have never been reliably reported from below 270 m depth. Here we describe large spherical protists, up to almost 40 mm diameter, recovered in box core, multicore, and epibenthic sledge samples taken on the continental slope off Oman (NW Arabian Sea) during RRS Discovery Cruise 211. Specimens consist of an organic envelope, with numerous tiny apertures, enclosing a mass of fine waste pellets (stercomata). On the basis of its wall ultrastructure (revealed by high-voltage transmission electron microscopy), this organism is identified as a member of the filosean genus Gromia. It is described herein as Gromia sphaerica sp. nov. The wall is layered and includes the ‘honeycomb membrane', a structure that is unique to this genus. The new species is the first gromiid to be reported from the deep sea. It lives between about 1200 and 1630 m below the main oxygen minimum zone, in an area where bottom-water oxygen concentrations are around 0.47 ml l?1. The new gromiid species is clearly visible in bottom photographs taken at 1273 m (2.7 individuals m?2), 1318 m (2.7 indiv. m?2), 1624 m (17.3 indiv. m?2) and 1633 m (76.5 indiv. m?2). They lie partly embedded in the seafloor and are sometimes grouped in twos and threes. Specimens are typically surrounded by an apron of lighter-coloured sediment, possibly resulting from their feeding activities. Where they lie in very close proximity, the apron around one specimen typically obscures adjacent tests