Quantitative biochronology of Pliocene and early Pleistocene calcareous nannofossils from the Atlantic,Indian and Pacific oceans

Semi-quantitative methods have been used to refine the precision with which Pliocene and early Pleistocene nannofossil datums may be applied for biostratigraphic purposes. Using these methods, the datums may be applied with a precision of between 0.01 m.y. (e.g.Calcidiscus macintyrei andDiscoaster brouweri) and 0.2 m.y. (e.g.Discoaster asymmetricus). The age of each datum is estimated by interpolation between magnetic reversals, so that the uncertainty in each age estimate is a function of proximity to the nearest reversal as well as of uncertainties in the reversal chronology but is probably better than 0.1 m.y. for all the datums studied here.The following ages are estimated for biostratigraphically useful datums: LADHelicosphaera sellii, 1.37 Ma (diachronous; earlier outside the equatorial zone); LADCalcidiscus macintyrei, 1.45 Ma; LADDiscoaster brouweri, 1.88 Ma; LADDiscoaster asymmetricus, 2.2 Ma; LAD DisDiscoaster pentaradiatus, 2.35 Ma; LADDiscoaster surculus, 2.41 Ma; LADDiscoaster tamalis, 2.65 Ma; LADDiscoaster variabilis, 2.90 Ma; LADSphenolithus spp., 3.45 Ma; LADReticulofenestra pseudoumbilica, 3.56 Ma; LADAmaurolithus delicatus, 3.66 Ma; FADCeratolithus rugosus, 4.62 Ma.The final 0.15 m.y. of the range ofDiscoaster brouweri is characterised by a high (about 20%) proportion of the triradiate form, which is a useful pointer for the extinction of this species even in the presence of considerable reworking.     

Sperm polymorphism within the sea urchin Strongylocentrotus droebachiensis: divergence between Pacific and Atlantic oceans

The rapid evolution of traits related to fertilization such as sperm morphology may be pivotal in the evolution of reproductive barriers and speciation. The sea urchin Strongylocentrotus droebachiensis has a circumarctic distribution and shows substantial genetic subdivision between northeastern Atlantic populations and northwestern Atlantic and Pacific populations. Using transmission electron microscopy, we show here that sperm shape, size, and ultrastructure differ markedly among populations of S. droebachiensis from different oceans and reflect patterns of genetic divergence. Sperm nuclei from northwestern Atlantic and Pacific populations were longer and narrower than those from the northeastern Atlantic. We additionally demonstrate population-level differences in the amount and location of filamentous actin (F-actin) prior to the occurrence of the acrosome reaction. Sperm from Pacific and northwest Atlantic populations differed from that of all other echinoids examined in that intact sperm contains a partly preformed acrosomal process, a structure more closely resembling the acrosomal rod seen in some molluscs. Immunofluorescent studies using anti-bindin antibodies and the F-actin-specific stain phalloidin confirmed these findings. Divergence of reproductive traits such as sperm morphology may be related to divergence in gamete compatibility and genetic divergence, and could represent the first stages of speciation in free-spawning marine invertebrates.     

Spatial structure of eukaryotic ultraplankton community in the northern South China Sea

Spatial distribution, diversity and composition of eukaryotic ultraplankton community of the northern South China Sea (nSCS) surface water and the relationship with the in situ water environment were investigated by the method of polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). A total of 18 DGGE intensive bands were detected and the sequence analysis of these DGGE bands revealed that Alveolata was the dominant eukaryotic ultraplankton group of surface water in the nSCS (50%). Other species belonged to Bicoecea, Bolidophyceae, Polycystinea and Chlorophyta, which accounted for less proportion of eukaryotic ultraplankton in the study area. Unweighted pair group method with arithmetic averages clustering of the sampling stations indicated that all stations were classified mainly based on geographical proximity. Redundancy analysis (RDA) was employed to further investigate the relationships between DGGE band pattern and the environmental variables. Based on the RDA analysis, temperature, salinity, phosphorus and silicate were the important factors to shape the eukaryotic ultraplankton community composition in the nSCS.     

New Pogonophora from the Atlantic and Pacific Oceans

A study of a collection of Pogonophora, made by the R.V. "Vema" in the Atlantic and Pacific Oceans, has revealed a total of 20 species. One of these, Lamellisabella ivanovi, was already known, the rest appear to be new. Seven species are described in detail, the others being represented only by tubes or insignificant fragments.     

Detection of stratified microbial populations related to Chlorobium and Fibrobacter species in the Atlantic and Pacific oceans.

A gene lineage (SAR406) related to Chlorobium and Fibrobacter species was found in 16S rRNA gene clone libraries prepared from samples from two oceans. The clone libraries were constructed from total picoplankton genomic DNA to assess bacterial diversity in the lower surface layer. The samples were collected by filtration from a depth of 80 m at a site in the western Sargasso Sea and from a depth of 120 m at a site in the Pacific Ocean, approximately 70 km from the Oregon coast. The PCR and primers which amplified nearly full-length 16S rRNA genes were used to prepare the clone libraries. Among the diverse gene clones in these libraries were two related clones (SAR406 and OCS307) which could not be assigned to any of the major bacterial phyla. Phylogenetic analyses demonstrated that these genes were distant relatives of the genus Fibrobacter and the green sulfur bacterial phylum, which includes the genus Chlorobium. The inclusion of SAR406 in phylogenetic trees inferred by several methods resulted in support from bootstrap replicates for the conclusion that Fibrobacter and Chlorobium species and SAR406 are a monophyletic group. An oligonucleotide probe that selectively hybridized to clone SAR406 was used to examine the distribution of this gene lineage in vertical profiles from the Atlantic and Pacific Oceans and in monthly time series at 0 and 200 m in the Atlantic Ocean. During stratified periods, the genes were most abundant slightly below the deep chlorophyll layer. Seasonal changes in the surface abundance of SAR406 rDNA were highly correlated with chlorophyll a levels (r = 0.75).     

Synonymy in peperomia berteroana (Piperaceae) results in biological disjunction between Pacific and Atlantic oceans

Placing Peperomia berteroana of the Juan Fernandez Islands in the Pacific Ocean in synonymy with P. tristanensis of Tristan da Cunha in the Atlantic Ocean results in a species with a wide geographical disjunction of more than 5000 km. Morphological data indicate that these taxa are best treated as subspecies (P. berteroana subsp. berteroana and P. berteroana subsp. tristanensis).     

Further characterization of eukaryotic initiation factor 5 from rabbit reticulocytes. Immunochemical characterization and phosphorylation by casein kinase II

Eukaryotic initiation factor (eIF)-5, isolated from rabbit reticulocyte lysates, is a monomeric protein of Mr = 58,000-62,000. Immunochemical methods were employed to identify eIF-5 in crude cell lysates. Antisera against purified denatured eIF-5 were prepared in rabbits and characterized by immunoblotting and immunoprecipitation techniques using native and denatured eIF-5 as antigens. Monospecific antibodies to denatured eIF-5 were affinity-purified using eIF-5 blotted onto aminophenylthioether paper. Rabbit reticulocytes, HeLa cells and mouse L cells were lysed directly into a denaturing buffer containing 3% sodium dodecyl sulfate. The denatured proteins were analyzed by polyacrylamide gel electrophoresis followed by immunoblotting with anti-eIF-5 antibodies. With each lysate, one major immunoreactive polypeptide was observed whose molecular weight corresponded to that of purified eIF-5 (Mr = 58,000-62,000). No degradation products or precursor forms of molecular weight higher than 62,000 were detected in any lysate. These results indicate that isolated eIF-5 is the same size as that found in crude lysates. Additional characterization of eIF-5 indicates that purified eIF-5 can be phosphorylated at serine residues in vitro by casein kinase II. Furthermore, in vitro phosphorylated eIF-5 retains full biological activity in catalyzing the joining of 60 S ribosomal subunits to a preformed 40 S ribosomal initiation complex to form an 80 S initiation complex. Based on its specific activity, we demonstrate that 1 pmol of rabbit reticulocyte eIF-5 mediates the formation of approximately 180 pmol of 80 S initiation complex under the conditions of in vitro initiation reactions.     

Taste preferences and feeding behavior of three-spined stickleback Gasterosteus aculeatus of populations of basins of the Atlantic and Pacific oceans

The absence of population specificity of taste spectra in fish was confirmed. It was found that the three-spined stickleback Gasterosteus aculeatus of populations of the North (Norway), Baltic (Latvia), and Okhotsk (Kamchatka Peninsula) seas has similar taste preferences to classical taste substances (sodium chloride, calcium chloride, and sucrose—10%; citric acid—5%) and to 21 free amino acids (L-isomers, 0.1–0.001 M). For fish of all populations, glutamine, glutamic and aspartic acids, and alanine have the most attractive taste; cysteine, asparagine, and histidine have slightly less attractive taste. In Baltic Sea and Sea of Okhotsk sticklebacks, relatively not numerous amino acids that cause a significant decrease in pellet consumption—phenylalanine, tryptophane, leucine, and tyrosine—coincide (in the North Sea stickleback, substances with deterrent taste were not revealed). In sticklebacks of different populations, no differences in manifestation of feeding behavior were found, and correlations between different elements of fish response to pellets are similar or close the same. It was shown that intraoral sensory testing of food objects in three-spined stickleback can proceed along two alternative behavioral stereotypes similar in fish of the studied populations. The dependence of stereotypes of intraoral testing on taste qualities of the food object was revealed for the first time.     

Large variability of bathypelagic microbial eukaryotic communities across the world's oceans

In this work, we study the diversity of bathypelagic microbial eukaryotes (0.8–20 μm) in the global ocean. Seawater samples from 3000 to 4000 m depth from 27 stations in the Atlantic, Pacific and Indian Oceans were analyzed by pyrosequencing the V4 region of the 18S ribosomal DNA. The relative abundance of the most abundant operational taxonomic units agreed with the results of a parallel metagenomic analysis, suggesting limited PCR biases in the tag approach. Although rarefaction curves for single stations were seldom saturated, the global analysis of all sequences together suggested an adequate recovery of bathypelagic diversity. Community composition presented a large variability among samples, which was poorly explained by linear geographic distance. In fact, the similarity between communities was better explained by water mass composition (26% of the variability) and the ratio in cell abundance between prokaryotes and microbial eukaryotes (21%). Deep diversity appeared dominated by four taxonomic groups (Collodaria, Chrysophytes, Basidiomycota and MALV-II) appearing in different proportions in each sample. Novel diversity amounted to 1% of the pyrotags and was lower than expected. Our study represents an essential step in the investigation of bathypelagic microbial eukaryotes, indicating dominating taxonomic groups and suggesting idiosyncratic assemblages in distinct oceanic regions.     

Immunochemical characterization of aldo-keto reductases from human tissues

Aldose reductase, aldehyde reductase and carbonyl reductase constitute a family of monomeric NADPH-dependent oxidoreductases with similar physical and chemical properties. Characterization of the enzymes from human tissues by immunotitration and an enzyme immunoassay indicated that, despite their apparent likeness, the three reductases do not cross-react immunochemically.     

Haplosporidiosis in the Pacific oyster Crassostrea gigas from the French Atlantic coast

Two cases of haplosporidian infection occurred during 1993 in Pacific oysters Crassostrea gigas from the French Atlantic coast. The localization and ultrastructure of the plasmodia are described. In situ hybridization of infected tissue sections was conducted with DNA probes for oyster-infecting haplosporidians. The Haplosporidium nelsoni-specific DNA probe MSX1347 hybridized with the C. gigas parasite, and the H. costale-specific probe SSO1318 did not hybridize. Total genomic DNA was extracted from the infected tissue sections for polymerase chain reaction (PCR) amplification of the haplosporidian. PCR amplifications with H. nelsoni-specific primers and with 'universal' actin primers did not yield the expected products of 573 and 700 bp, respectively. A series of primers was designed to amplify short regions of small subunit ribosomal DNA (SSU rDNA) from most haplosporidians. The primers encompass a highly variable region of the SSU rDNA and did not amplify oyster DNA. PCR amplification of the infected C. gigas genomic DNA with these primers yielded the expected-sized product from the primer pair targeting the shortest region (94 bp). This PCR product was sequenced and it was identical to the corresponding SSU rDNA region of H. nelsoni.     

Immunochemical characterization of synaptosomal membrane antigens from chicken brain

Quantitative microcomplement fixation assays have been used to partially characterize a set of nerve-specific membrane antigens. Their sensitivity to proteolytic enzymes suggested that most, or all, of the antigens contain protein, and the stimulatory effect of neuraminidase treatment suggested that some were glycoproteins. The antigens were found to be approximately 100 times more concentrated in neuronal tissues than in nonneural tissues, except for the adrenal, and they were found to be absent from the forebrains of nonavian species. The changes in total and specific activity have been measured during development in a number of neuronal tissues and compared with previously obtained immunohistochemical data.     

Immunochemical characterization of proteins from mouse liver plasma membranes

1. Antiserum was prepared in rabbits against a purified mouse liver plasma-membrane fraction. 2. The antiserum was made to react with an ¹²⁵I-labelled alkaline-EDTA extract of the plasma membranes, and the immunoprecipitate analysed by polyacrylamide-gel electrophoresis. Seven proteins were immunoprecipitated and a single glycoprotein present in the alkaline-EDTA-soluble fraction was found to be a major component. 3. The alkaline-EDTA-soluble fraction was analysed by two-dimensional immunoelectrophoresis and this procedure indicated the presence of six antigenic components. 4. The plasma membranes were also extracted with 1% deoxycholate–1% Triton X-100; 50% of the protein, 80% of the alkaline phosphodiesterase activity and 30% of the 5′-nucleotidase activity were solubilized. 5. Two-dimensional immunoelectrophoresis of the deoxycholate–Triton X-100 extract indicated the presence of six antigens. 6. The relative distribution of the six antigens among the fractions obtained during the extraction procedure was examined immunoelectrophoretically to provide information on their disposition within the membrane.     

Immunochemical characterization of synaptosomal membrane antigens from chicken brain

A set of synaptic membrane antigens has been investigated in a number of tissues by indirect immunofluorescence histochemistry, using an antiserum (SPM-I) raised against a purified synaptosomal plasma membrane fraction prepared from day-old chick forebrain. The antigens were found to be present in both the central and peripheral nervous systems and none of them were restricted to the forebrain. The antigens were not detectable in nonneural tissues except for the adrenal medulla. Since the antigens could not be detected in a number of clearly defined glial cell populations or a surgically induced gliosis of the optic nerve, the antigens appear to be nerve specific. The antigens were not present in all types of neurons, thus indicating that surface membrane differences exist between different classes of neurons. Within the plasma membrane of the nerve cell the antigens were not uniformly distributed: they were present in the synaptic region and, in some nerve cells, also in axonal region but were absent from perikaryal membranes and extended regions of dendritic membranes. In the sciatic nerve the antigens were transported at the fast rate of anterograde axonal transport as well as in the retrograde direction. These results have been compared with previous attempts to detect nerve-specific membrane components by immunological means.Part of this work has been presented at American Society for Neurochemistry Meeting, New Orleans, March 1974.