radiolaria - Marum

Radiolaria 14 Bibliography - 1989
role for age dating, zonation and correlation of the Kimmeridge Clay
Formation of the northern North Sea. 13 radiolarian events are
recognized, including species "tops", "acmes" and "bases" which
are distributed throughout the Kimmeridge Clay Formation. The
correlation of these events is discussed in two wells from the
northern North Sea. This suggests that the group can provide an
important contribution towards stratigraphic evaluation of the
formation in offshore exploration wells. The taxonomy of certain
stratigraphically important species is briefly reviewed.
El Kadiri, K., Linares, A. & Olóriz, F. 1989. La
Dorsale calcaire interne entre les Accidents de l'Oued Laou (Rif
septentrional, Maroc): évolutions stratigraphique et
géodynamique au cours du Jurassique-Crétacé. Comunic. Serv.
geol. Port., 75, 39-65.
Elorza, J.J. & Bustillo, M.A. 1989. Early and Late
Diagenetic Chert in Carbonate Turbidites of the Senonian
Flysch, northeast Bilbao, Spain. In: Siliceous Deposits of
the Tethys and Pacific Regions. (Hein, J.R. & Obradovic, J.,
Eds.). Springer-Verlag, New York. pp. 93-106.
Sedimentological and petrographical analysis of the lower
Senonian flysch (Plencia Fm.), near Barrika village, and a part of the
upper Senonian flysch (Eibar Fm. ) show three types of diagenetic
silicification: Bedded and nodular chert, chert in poorly developed
laminites, and fracture-related chert. The beds and nodules of early
formed chert and chert in laminites occur in the Tb, Tc, and Td Bouma
intervals in the carbonate turbidites. The original sedimentary
structures are preserved in the cherts. The fracture-related chert
has a later diagenetic origin, and cross-cuts the sedimentary
structures and the early-formed chert. Silica minerals include
microquartz and length-fast chalcedony in the bedded, nodular, and
fracture-related chert. Microquartz and length-slow chalcedony
(quartzine) compose laminite-hosted chert.
No differences exist in the abundance of minor elements among
all the types of chert. The contents in Zr, Pb, Rb, and Zn are higher
than the amounts commonly found in these types of cherts from
other areas, and these elements may be associated with the iron
oxides.
The silica of the bedded and nodular chert was derived from the
early dissolution and calcitization of sponge spicules and
radiolarians mixed in with the carbonate turbidites. The late stage
fracture-related chert apparently came from a later-stage
calcitization of siliceous tests and perhaps also from a partial silica
remobilization of the early-formed chert.
Febvre, J. & Febvre-Chevalier, C. 1989a. Motility
processes in Acantharia. II - A Ca 2+ dependent system of
contractile 2-4 nm filamens isolated from demembranated
myonemes. Biol. Cell, 67, 243-249.
Myonemes of the acantharians are contractile ribbon-like
organelles. As previously shown, their motility is based on the coiling
mechanism of double-twisted 2—4 nm nonactin filaments.
Myonemes have been isolated and manipulated in vitro. After
demembranation, the contraction takes place when the Ca 2+
concentration is above 10 -7 M, whereas relaxation occurs below this
threshold concentration. The response to Ca 2+ ions is an on/off
mechanism. Both contraction and relaxation can be induced
repeatedly without fatigue phenomena- Other divalent cations such
as Sr 2+ , Ba 2+ , Mn 2+ , CO 2+ , and La 3+ can replace Ca 2+ in inducing
contraction of the demembranated myonemes although with less
efficiency. Contraction and relaxation are ATP-independent and
calmodulin ;s not involved in this in vitro motility process. The
myoneme is a strongly resistant structure which is capable of
contracting and relaxing under various extreme conditions which
indicates very stable proteins and resistant functions.
Febvre, J. & Febvre-Chevalier, C. 1989b. Motility
and processes in Acantharia (Protozoa). III - Calcium
regulation of the contraction-relaxation cycles of in vivo
myonemes. Biol. Cell, 67, 251-261.
The myonemes in the marine pelagic-protozoa Acantharia are
contractile organelles involved in buoyancy regulation. It was
previously shown that they can perform three kinds of movement:
rapid contraction, slow undulation and slow relaxation. They consist
of a periodically striated bundle of 2-4 nm nonactin fi!aments that
are twisted in pairs and shortened by a coiling mechanism. After
permeabilization or demembranation, contraction and relaxation can
still be performed by varying Ca 2+ concentration and ATP is not
needed.
In the present paper, we have studied the role of Ca 2+ and
inhibitors of energy production in intact cells. Our data suggest that;
(i) the in vivo rapid contraction subsequent to mechanical or
electrical stimulation is triggered by Ca 2+ influx across the cell
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membrane; (ii) the slow contraction that takes place during the
undulating movement depends on Ca 2+ release provided by internal
calcium stores; (iii) the rapid contraction as well as the progressive
shortening that occurs during the slow undulating movement are
caused by Ca 2+ binding to the myoneme-filaments; (iv) ATP is not
directly involved in the saturation by Ca 2+ of Ca 2+ sensitive sites
located along the myoneme microstrands; (v) regulation of the
movements of Ca 2+ within the cytoplasm depends mainly upon the
alternative pathway of ATP production; (vi) calmodulin is presumably
involved in this regulation. A tentative cytophysiologic interpretation
of the mechanism of contractility is proposed.
Fujita, H. 1989. Stratigraphy and geologic structure of the
Pre-Neogene strata in the Central Ryukyu Islands. J. Sci.
Hiroshima Univ., Ser. C: Geol. Min., 9/1, 237-284.
The stratigraphy and geologic structure of the pre-Neogene
strata in the northwestern Okinawa islands and the northern Amami
islands were investigated in order to clarify the sedimentary and
tectonic history of Central Ryukyu during the late Paleozoic to
Paleogene period. The pre-Neogene strata of Central Ryukyu form an
asymmetrically folded structure in each of the tectonic units
separated by reverse or thrust faults dipping generally toward the
northwest, and as a whole they form an imbricate structure. The pre-
Neogene strata in the northwestern Okinawa islands are classified
into the following formations roughly from northwest to southeast:
Iheya, Izena, Maedake and Ie formations (Permian to early
Cretaceous ?), Dana and Moromi formations (late Cretaceous ?),
Nakijin formation (Carnian) and Gusukuyama formation (Oxfordian to
Tithonian), Motobu formation (PermiantoTriassic?) and Yonamine
formation (Valanginian to Barremian), Wakugawa formation (late
Albian to Cenomanian ?), Nago formation (Cenomanian to Santonian
?) and Kayo formation (early middle Eocene). The pre-Neogene
strata in the northern Amami islands are divided, from west to east,
into the Yuwan formation (Oxfordian to Berriasian), Yuwandake
formation (Valanginian to middle Albian), Odana formation (late
Albian to Cenomanian), Naze and Ogachi formations (Cenomanian to
Santonian ?) and Wano formation (Eocene). Excepting the Dana,
Moromi, Kayo and Wano formations, the pre-Neogene strata become
generally younger from northwest or west to southeast or east in
both districts. These pre-Neogene strata are characterized by the
development of subaqueous slumping or sliding. Especially, the
Yonamine, Yuwan and Yuwandake formations comprise a large
amount of olistostromes in which olistoliths were derived chiefly
from the northwestern area. The polarity in geological age toward the
southeast and the inferred source of olistoliths may suggest that
the sedimentary basins of thesepre-Neogene strata migrated southeastward
during late Jurassic to late Cretaceous time.
In the pre-Neogene strata, "slump structures" and tectonic
structures are observed. The tectonic structures are classified into
I, flexural slip folds; II, reverse faults and asymmetric folds with
cleavages; III, thrust faults and associated folds; IV, strike slip
faults; V, normal, lag and reverse faults. The tectonic structures I, II,
and III take part in the asymmetrically folded and imbricated
structure parallel to the extension of the pre-Neogene strata, while
the tectonic structures IV and V cut it obliquely. The formation of
the asymmetrically folded and imbricated structure in the pre-
Neogene strata may be closely related to the migration of the
sedimentary basins.
Garrison, D.L. & Buck, K.R. 1989. Protozooplankton
in the Weddell Sea, Antarctica: abundance and distribution in
the ice-edge zone. Polar Biol., 9, 341-351.
Protozooplankton were sampled in the ice-edge zone of the
Weddell Sea during the austral spring of 1983 and the austral
autumn of 1986. Protozooplankton biomass was dominated by
flagellates and ciliates. Other protozoa and micrometazoa
contributed a relatively small fraction to the heterotrophic biomass.
During both cruises protozoan biomass, chlorophyll a
concentrations, phytoplankton production and bacterial biomass and
production were low at ice covered stations. During the spring
cruise, protozooplankton, phytoplankton, and bacterioplankton
reached high concentrations in a well-developed ice edge bloom
~100 km north of the receding ice edge. During the autumn cruise,
the highest concentrations of biomass were in open water wellseparated
from the ice edge. Integrated protozoan biomass was
20%.
Bacterial biomass exceeded protozooplankton biomass at ice
covered stations but in open water stations during the fall cruise,
protozooplankton biomass reached twice that of bacteria in the
upper 100m of the water column. The biomass of different
protozoan groups was positively correlated with primary production,
chlorophyll a concentrations and bacterial production and biomass,
suggesting that the protozoan abundances were largely controlled by
prey availability and productivity. Population grazing rates
calculated from clearance rates in the literature indicated that
protozooplankton were capable of consuming significant portions of
the daily phyto- and bacterioplankton production.