Silicoflagellate abundance in ODP Holes 183-1138A and 183-1140A

The biostratigraphic distribution and abundance of lower Oligocene and Miocene to Pleistocene silicoflagellates are documented from Ocean Drilling Program Leg 183 Holes 1138A and 1140A, on the Kerguelen Plateau. The Distephanus speculum speculum forma pseudofibula plexus is found in the upper Miocene in Hole 1138A, but other important biostratigraphic markers are not available. Diversity and abundance of silicoflagellates vary considerably in Hole 1138A, with silicoflagellates more abundant in the Pliocene and Pleistocene and some intervals of the Miocene barren of silicoflagellates or containing only limited numbers of specimens. The silicoflagellates of Hole 1140A include a new skeletal morphology, described here as Distephanus speculum speculum forma cylindrus. Silicoflagellates were generally abundant throughout the lower and middle Miocene in Hole 1140A.

North Atlantic late Miocene stable-isotope stratigraphy, biostratigraphy, and magnetostratigraphy

Upper Miocene foraminiferal nannofossil ooze and chalk from DSDP Hole 552A in the northeast Atlantic Ocean have been closely sampled for biostratigraphic, paleomagnetic, and stable-isotopic studies. Sampling at 10-cm intervals resulted in an uppermost Miocene isotope stratigraphy with a 1000- to 3000-yr. resolution. Covariance in benthic (Planulina wuellerstorfi) and planktonic (Globigerina bulloides) foraminiferal d18O records is taken as evidence for variability in continental ice volume. Our best estimate is that glacial maxima occurred at -5.0 and ~ 5.5 Ma and lasted no more than 20,000 yrs. These events probably lowered sea level by 60 m below the latest Miocene average. There is little oxygen-isotope evidence, however, for a prolonged glaciation during the last 2 m.y. of the late Miocene. High- and low-frequency variability in the d13C record of foraminifers is useful for correlation among North Atlantic DSDP Sites 408, 410, 522, 610, and 611, and for correlation with sites in other oceans. Similar d13C changes are seen in P. wuellerstorfi and G. bulloides, but the amplitude of the signal is always greater in G. bulloides. Variability in d13C common to both species probably reflects variability in the d13C of total CO2 in seawater. Major long-term features in the d13C record include a latest Miocene maximum (P. wuellerstorfi = 1.5 per mil ) in paleomagnetic Chron 7, an abrupt decrease in d13C at -6.2 Ma, and a slight increase at -5.5 Ma. The decrease in d13C at -6.2 Ma, which has been paleomagnetically dated only twice before, occurs in the upper reversed part of Chronozone 6 at Holes 552A and 611C, in excellent agreement with earlier studies. Cycles in d13C with a period of ~ 10 4 yrs. are interpreted as changes in seawater chemistry, which may have resulted from orbitally induced variability in continental biomass. Samples of P. wuellerstorfi younger than 6 Ma from throughout the North Atlantic have d13C near lo, on average ~ l per mil greater than samples of the same age in the Pacific Ocean. Thus, there is no evidence for cessation of North Atlantic Deep Water production resulting from the Messinian "salinity crisis." Biostratigraphic results indicate continuous sedimentation during the late Miocene after about -6.5 Ma at Hole 552A. Nannofossil biostratigraphy is complicated by the scarcity of low-latitude marker species, but middle and late Miocene Zones NN7 through NN11 are recognized. A hiatus is present at -6.5 Ma, on the basis of simultaneous first occurrences of Amaurolithusprimus, Amaurolithus delicatus, Amaurolithus amplificus, and Scyphosphaera globulata. The frequency and duration of older hiatuses increase downsection in Hole 552A, as suggested by calcareous nannofossil biostratigraphy and magnetostratigraphy. Paleomagnetic results at Hole 552A indicate a systematic pattern of inclination changes. Chronozone 6 was readily identified because of its characteristic nannoflora (sequential occurrences of species assigned to the genus Amaurolithus) and the d13C decrease in foraminifers, but its lower reversed interval is condensed. Only the lower normal interval of Chronozone 5 was recognized at Hole 552A; the upper normal interval and the lowest Gilbert sediment are not recognized, owing to low intensity of magnetization and to coring disturbance. Interpreting magnetic reversals below Chronozone 6 was difficult because of hiatuses, but a lower normally magnetized interval is probably Chronozone 7. Correlation between DSDP Hole 552A and other North Atlantic sites is demonstrated using coiling direction changes in the planktonic foraminifer Neogloboquadrina. At most sites this genus changed its coiling preference from dominantly right to dominantly left during the late Miocene. At Hole 552A this event probably occurred about 7 m.y. ago. At the same time, P. wuellerstorfi had maximum d13C values. A similar d13C maximum and coiling change occurred together in Chron 7 at Hole 611C, and at Hole 610E. In sediment younger than -5.5 Ma, the coiling of small Neogloboquadrina species is random, but the larger species N. atlantica retains preferential left coiling.

Paleocene-Eocene calcareous nannofossils of onshore wells from the Coastal Plain of New Jersey and Maryland, USA

Paleogene calcareous nannofossils from split spoon cores recovered from five wells along the Coastal Plain of New Jersey and Maryland have been analyzed in order to provide onshore information complementary to that derived from the offshore DSDP Site 605 (upper continental rise off New Jersey). Hiatuses are more numerous and of greater extent in the onshore sections, but the major ones correlate well with those noted in the offshore section. At one site at least (Leggett Well), sedimentation may well have been continuous across the Cretaceous/Tertiary boundary, as it is believed to have been at DSDP Site 605. These various correlations are discussed elsewhere in a companion paper (Olsson and Wise, this volume). Important differences in nannofossil assemblages are noted between the onshore (shelf paleoenvironment) and offshore (slope-rise paleoenvironment) sections. Lithostromation simplex, not present offshore, is consistently present onshore and seems to be confined to the Eocene shelf sediments of this region. The same relationship holds for the zonal marker, Rhabdosphaera gladius Locker. The Rhomboaster-Tribrachiatus plexus is more diverse and better preserved in the onshore sections, where the lowermost Eocene Zone CP9 is well represented. Differential preservation is postulated to account for two morphotypes of Tribrachiatus bramlettei (Brönnimann and Stradner). Type A is represented at DSDP Site 605 by individuals with short, stubby arms, but these forms are not present in the equivalent onshore sections. There they are replaced by the Type B morphotypes, which exhibit a similar basic construction but possess much longer, more delicate arms.

Eocene to Quaternary planktonic foraminifers from the Northwest Pacific

Eocene through Quaternary planktonic foraminifers were identified in cores recovered during Leg 126. Turbidites and volcanic ash beds are intercalated with hemipelagic sediments. Preservation of foraminifers is variable, ranging from excellent to poor and appears to have been affected by fluctuations in the carbonate compensation depth (CCD), depth of burial, changes in bottom water temperature, current velocity, sediment accumulation rates and seafloor topography. Preservation of foraminifers in Quaternary sediments is generally good, however, species abundance varies by a factor of I05-106 and reflects dilution by volcanogenic as well as terrigenous constituents and cannot be used for paleoceanographic reconstructions. In pre-Quaternary deposits planktonic foraminiferal tests frequently exhibit dissolution effects; biostratigraphic zonation and placement of zonal boundaries is difficult owing to hiatuses, dissolution facies, extraneously deposited sediments, and discontinuous coring. The Eocene foraminiferal faunas include specimens of the Globorotalia cerroazulensis plexus, markers of Zone P16 as well as Globigerina senni and Globigerinatheka spp., which became extinct before the end of the Eocene. Six hiatuses and/or dissolution periods, probably reflecting global cooling events and/or changes in oceanic circulation patterns were recorded at Site 792. Recrystallized, poorly preserved, possibly reworked Eocene species (Globigerina senni and Globigerapsis sp.) were recorded in sediments at Site 793.

Silicoflaggelates from ODP Leg 120 on the Kerguelen Plateau

The biostratigraphic distribution and abundance of Eocene to Pleistocene silicoflagellates is documented from Ocean Drilling Program Leg 120 Holes 747A, 748A, 748B, 749B, and 751A on the Central Kerguelen Plateau. Well-preserved silicoflagellates are reported here from the middle Eocene Dictyocha grandis Zone to the Pleistocene Distephanus speculum speculum Zone. Assemblage diversity and abundance is variable, with many intervals either barren of silicoflagellates or containing only limited numbers.

Early Cretaceous dinoflagellate cycsts from ODP Hole 123-765C

Results of a preliminary study of Early Cretaceous dinocyst assemblages from Site 765 on the Argo Abyssal Plain, off northwestern Australia, are presented. The palynological sequence is interpreted in terms of Australian zones and is, in descending order, the late Aptian Diconodinium davidii Zone (Cores 123-765C-33R to -39R), the middle to early Aptian Odontochitina operculata Zone (Cores 123-765C-40R to -49R), the Barremian Muderongia australis Zone (Cores 123-765C-50R to -54R), and the Berriasian lower Batioladinium reticulatum Zone (Core 123-765C-59R). The dating of the sequence as late Aptian to Berriasian on the basis of dinocysts is supported, in part, by data concerning associated foraminiferal, radiolarian, and calcareous nannofossil suites.

Relative abundances of stratigraphically useful planktonic foraminifers from ODP Leg 167 sites

Late Neogene biostratigraphy of planktonic foraminifers has been investigated from 13 sites cored during Ocean Drilling Program Leg 167 off the coast of California. The planktonic foraminiferal biostratigraphy of six of these sites is presented here at higher stratigraphic resolution for the interval that encompasses the late early Pliocene through the Quaternary (~3.5 Ma to present day). The sites form a transect along the California margin from 31°N to 41°N within the California Current system. A new planktonic foraminiferal zonation has been established largely on evolutionary changes within the Neogloboquadrina plexus, supported by other taxa. A total of eight zones are recognized, most of which are broadly applicable throughout the region, thus providing a biostratigraphic zonation of the sequence at ~0.5-m.y. intervals. The new zonation appears to be unique to the California Current system. The diversity of planktonic foraminiferal assemblages during the late Neogene appears to have remained relatively constant despite large-scale paleoclimatic change. The assemblages are consistently dominated by few taxa that almost always include the neogloboquadrinids and Globigerina bulloides. Low diversity and high dominance of the assemblages favored these and other taxa well adapted to upwelling systems exhibiting high seasonal surface ocean variability. Apparently the oceanographic conditions that favor such assemblages have persisted at least for the duration of the late Neogene (~3.5 Ma to present day). The biostratigraphically important forms have been illustrated with scanning electron micrographs.

Conception d’un éco-quartier sur le site Masséna Bruneseau

Le projet à développer c’était la conception d’un éco-quartier dans une zone actuellement couverte par des voies ferrées à Paris Rive Gauche. C’était un travail complètement nouveau pour moi. Je n’avais bien sûr jamais élaboré un plan de masse par exemple. Mais le travail d’ingénierie que nous avons rendu était également : il s’agissait de prendre des ordres de grandeur de dépenses énergétiques, et non d’en étudier chaque caractéristique précisément. Ainsi, à partir d’un site très contraint – problèmes de pente, de proximité du périphérique pour ne citer que ces aspects -, nous avons donc entièrement conçu un éco-quartier avec son plan de masse, ses ambiances de rez-de-chaussée, mais aussi ses solutions techniques pour satisfaire les critères HQE. Nos maîtres mots étaient mixité, écologie, création de lieux de vie, et respect du lieu et de son histoire. Pour réaliser un tel projet, nous avons donc aiguisé notre regard sur la ville, nous nous sommes promenés dans divers quartiers parisiens, rendus à des colloques d’urbanistes, et les conseils avisés de Mr Gilles de Montmarin et Mr Jean Jacques Obriot furent très fructueux, nous tenons ici à les en remercier. Voici donc le fruit de notre travail d’un an, nous présentons d’abord le projet dans sa globalité, puis nos réalisations lors du premier et du deuxième semestre.

Vista de Valencia [Material gráfico]

Basado en la litografía de Bichebois pero más simplificada: "Vue prise de la rive gauche du Guadalaviar. Tomada de la ribera izquierda del Guadalaviar à Paris, chez Bulla éditeur, rue Tiquetonne, 18. Lith. par Bichebois et Dumouza. Fig. par Bayot. Imp. Lemercier Bernard et C."

Induction of inhibitory factor κBα mRNA in the central nervous system after peripheral lipopolysaccharide administration: An in situ hybridization histochemistry study in the rat

In this study we investigate the mRNA expression of inhibitory factor κBα (IκBα) in cells of the rat brain induced by an intraperitoneal (i.p.) injection of lipopolysaccharide (LPS). IκB controls the activity of nuclear factor κB, which regulates the transcription of many immune signal molecules. The detection of IκB induction, therefore, would reveal the extent and the cellular location of brain-derived immune molecules in response to peripheral immune challenges. Low levels of IκBα mRNA were found in the large blood vessels and in circumventricular organs (CVOs) of saline-injected control animals. After an i.p. LPS injection (2.5 mg/kg), dramatic induction of IκBα mRNA occurred in four spatio-temporal patterns. Induced signals were first detected at 0.5 hr in the lumen of large blood vessels and in blood vessels of the choroid plexus and CVOs. Second, at 1–2 hr, labeling dramatically increased in the CVOs and choroid plexus and spread to small vascular and glial cells throughout the entire brain; these responses peaked at 2 hr and declined thereafter. Third, cells of the meninges became activated at 2 hr and persisted until 12 hr after the LPS injection. Finally, only at 12 hr, induced signals were present in ventricular ependyma. Thus, IκBα mRNA is induced in brain after peripheral LPS injection, beginning in cells lining the blood side of the blood–brain barrier and progressing to cells inside brain. The spatiotemporal patterns suggest that cells of the blood–brain barrier synthesize immune signal molecules to activate cells inside the central nervous system in response to peripheral LPS. The cerebrospinal fluid appears to be a conduit for these signal molecules.

Leptin and leptin receptor mRNA and protein expression in the murine fetus and placenta

Leptin is a 167-aa protein that is secreted from adipose tissue and is important in the regulation of energy balance. It also functions in hematopoiesis and reproduction. To assess whether leptin is involved in fetal growth and development we have examined the distribution of mRNAs encoding leptin and the leptin receptor (which has at least six splice variants) in the 14.5-day postcoitus mouse fetus and in the placenta using reverse transcription–PCR and in situ hybridization. High levels of gene expression for leptin, the leptin receptor, and the long splice variant of the leptin receptor with an intracellular signaling domain were observed in the placenta, fetal cartilage/bone, and hair follicles. Receptor expression also was detected in the lung, as well as the leptomeninges and choroid plexus of the fetal brain. Western blotting and immunocytochemistry, using specific antibodies, demonstrated the presence of leptin and leptin receptor protein in these tissues. These results suggest that leptin may play a role in the growth and development of the fetus, both through placental and fetal expression of the leptin and leptin receptor genes. In the fetus, leptin may be multifunctional and have both paracrine and endocrine effects.

Molecular identification of a novel retrovirus repeatedly isolated from patients with multiple sclerosis

The partial molecular characterization of multiple sclerosis (MS)-associated retrovirus (MSRV), a novel retrovirus previously called LM7, is reported. MSRV has been isolated repeatedly from leptomeningeal, choroid plexus and from Epstein–Barr virus-immortalized B cells of MS patients. A strategy based on reverse transcriptase PCR with RNA-purified extracellular virions yielded an initial pol fragment from which other regions of the retroviral genome were subsequently obtained by sequence extension. MSRV-specific PCR primers amplified a pol region from RNA present at the peak of reverse transcriptase activity, coinciding with extracellular viral particles in sucrose density gradients. The same sequence was detected in noncellular RNA from MS patient plasma and in cerebrospinal fluid from untreated MS patients. MSRV is related to, but distinct from, the endogenous retroviral sequence ERV9. Whether MSRV represents an exogenous retrovirus with closely related endogenous elements or a replication-competent, virion-producing, endogenous provirus is as yet unknown. Further molecular epidemiological studies are required to determine precisely the apparent association of virions containing MSRV RNA with MS.