The deciduous dentition and dental replacement in the Eocene bat Palaeochiropteryx tupaiodon from Messel: The primitive condition and beginning of specialization of milk teeth among Chiroptera

The deciduous dentition and tooth replacement pattern of Palaeochiropteryx tupaiodon from the early Middle Eocene of Messel, near Frankfurt, Germany, are described. Ontogenetic states include fetuses to subadults. The posterior portion of the deciduous dentition (dP3-4) still shows the primitive eutherian condition of molarization, while the anterior part (dI-dC) was already engaged in the evolution of the highly derived condition found in living bats for clinging to the mother's fur. A styliform and sharp anterior dentition is considered a prerequisite in earliest chiropteran evolution. The greatly modified milk teeth of all living bats developed in different clades by parallel evolution under high selective pressure. The tiny and, at initial stages, poorly calcified teeth are substantiated by a newly developed microradiographic technique which is described in detail.     

HYDRAULIC BURROWING IN THE BIVALVE MYA ARENARIA LINNAEUS (MYOIDEA) AND ASSOCIATED LIGAMENTAL ADAPTATIONS

The burrowing behaviour of the bivalve Mya arenaria from tidalflats of the Dutch Wadden Sea has been observed and recorded.Compared to other bivalves, M. arenaria is a very slow burrower,its burrowing behaviour being unique among bivalves since itis based essentially on the ejection of water through the pedalgape, with little assistance by the foot, which performs onlyan anchoring function. Water ejection is specially powerfuland individual jets may last several seconds, thus constitutingan effective means of removing sand from below the animal duringdigging. This hydraulic burrowing is more effective in loosesandy than in cohesive muddy substrates. Water ejection is providedby the ability of the bivalve to rock its valves across a dorsoventralaxis. This rocking motion implies special modifications of theligamental area. The ligament is conical in appearance and runsdorso-ventrally between the two chondrophores which are placedin two planes parallel to the cardinal axis. During rockingthe whole ligament acts in torsion and the lamellar layer ofthe ligament opposes closing of the anterior part of the valves.During normal adduction of the valves the ligament acts in bending,the axis of motion being placed internally with respect to thecardinal axis. This leads to approaching of the umbones withcomplete adduction and to resorption of the left umbo. Fromthe adaptive point of view, the slow hydraulic mode of burrowingis sufficient to cope with the slow sedimentation and erosionrates of the tidal flats in which M. arenaria lives. This burrowingmode implies the existence of a tiny foot, which leaves roomfor other organs within the mantle cavity. This, together withanterior divarication of the valves permits a large volume ofwater to be ejected from the mantle cavity, but, in the caseof M. arenaria, also the existence of an enormous stomach, possiblyas an adaptation for food processing. (Received 12 April 1996; accepted 2 October 1996)     

Jurassische Pflanzenreste aus einem Geschiebe-Gerdll votn Ostseestrand der Mecklenburger Bucht

In einem Toneisenstein, der ala Strandgeröll westlich Heiligendamm an der Ostsee gefunden wurde, werden jurassische Pflanzenreste bekanntgemacht. Es handelt sich um Coniopteris hymenophylloides (Brongniart) Seward, ein Ginkgophyten-Blattfragment und einen fast vollständigen Thallus eines Lebermooses, das als Marchantiolites cf. porosus Lundblad bezeichnet wird. Außer ausführlicher Beschreibung und Erläuterung der Fossilien werden auch Bemorkungen zur Stratigraphio und mogliehen Herkunft dea vermutlich glazialen Strandgerölls gemacht.
Jurassic plant remains are described from a clay-ironstone boulder, found on the shore of the Baltic Sea west of Heiligendamm. The plants comprise Coniopteris hymenophylloides (Brongniart) Seward, a leaf fragment of a ginkgophy te and an almost complete thallus of a liverwort which is identified as Marchantiolites cf. porosus Lundblad. The fossils are described and interpreted, and the stratigraphy and origin of this presumed glacial erratic discussed.     

THE MOLLUSCAN RHOGOCYTE (PORE-CELL, BLASENZELLE, CELLULE NUCALE), AND ITS SIGNIFICANCE FOR IDEAS ON NEPHRIDIAL EVOLUTION

The rhogocyte (Leydig's cell, cellule nucale, Blasen-zelle,pore cell) is a specific molluscan cell type that occurs throughoutthe animal's primary body cavity, i.e free in the haemocoelor embedded in connective tissue. Rhogocytes closely resemblecyrtocytes and podocytes jn having slit-Uke diaphragms withan encoating extracellular matrix at their surface which probablyacts as a molecular sieve However, rhogocytes are solitary cells,whereas cyrtocytes and podocytes form epitheha Occurrence, variability,naming, and possible functions of the rhogocyte among the MoUuscaare reviewed and discussed. In general, rhogocytes play an importantrole in metal ion metabolism of molluscs, they are possiblyinvolved in the recycling of respiratory pigments and may alsoact in detoxification. Up to now direct homologues of the molluscan rhogocyte havenot been described in any other bi-laterian phylum, so-called‘pore cells’ of other phyla show entirely differentfine-structures However, at least partial (serial) homologycan be accepted between rhogocytes (free cells), arthropod nephro-cytes(cell aggregates or solitary cells) and podocytes (true epithelialcells), and there is also a cytological and functional continuumof both rhogocytes and podocytes to protonephndial cyrto- respectivelysolenocytes. Implications of this postulated ‘cell-family’with slit-diaphragms and their respective ultrafiltration systemsfor theories on the evolution of filtration nephndia are discussed. (Received 10 February 1995; accepted 10 October 1995)     

Taxonomic importance of seed morphology in Gentiana (Gentianaceae)

The seeds of Gentiana show high diversity in size, shape and surface pattern. Until now, seeds of only a limited number of taxa have been studied in detail and their utility in the subgeneric classification of Gentiana has not been evaluated. In this study we investigated seed micromorphology of the poorly known sections Pneumonanthe, Frigidae and Isomeria. In order to evaluate the relevance of seed sculpturing for taxonomy, we selected qualitative characters of seed shape and testa ornamentation of all documented sections and performed cluster analyses based on presence and absence of coded characters. Several new scanning electron microscopy pictures of seeds provided a number of valuable characters for the subgeneric differentiation of Gentiana. The results of the cluster analyses of seed characters generally support the sectional classification given by former authors. However, the European Gentiana asclepiadea does not group together with other taxa of section Pneumonanthe, but clusters near to the strictly European section Gentiana. Gentiana froelichii, endemic to the south‐east Alps and treated traditionally within section Frigidae, clusters together with taxa of the European section Ciminalis. Our results reveal that seed micromorphology supports the reassignment of some taxa incertae sedis within Gentiana. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 162 , 101–115.     

Hormonal control of lutein incorporation into pupal cuticle of the butterfly Inachis and the pupal melanization reducing factor

Abstract. . Morphological colour adaptation of pupae of the butterfly Inachis io L. (Lepidoptera: Nymphalidae) is controlled by a factor which reduces cuticular melanization (Biickmann & Maisch, 1987). This so-called pupal melanization reducing factor (PMRF) is located throughout the entire central nervous system of prepupae (Stamecker et al. , 1994).
Extracts of abdominal ganglia also stimulated dose-dependently lutein incorporation into pupal cuticle. In the bioassay higher doses were required to increase cuticular lutein content than to reduce melanization. Ligatures during the prepupal stage demonstrated two different critical periods for these pigmentation effects: an early one for melanization reduction and a late one for lutein incorporation.
An initial chromatographic purification yielded only two adjacent fractions which contained both the PMRF and the stimulation of lutein incorporation activity. Therefore it is assumed that only one hormone with a dual function may be responsible for pupal pigmentation.
Lutein content was found in gut, fat body, epidermis and haemolymph of I.io. Lutein incorporation into cuticle occurred within 1.5 days of the pupal moult when the cuticle was not yet fully sclerotized. Lutein content is significantly higher in cuticle of yellow pupae than of black ones.     

Apparent Differences in Transcriptional Control in Cells productively Infected and Transformed by SV40

Synthesis of viral DNA seems to be necessary for the production of “late” SV40 mRNA. Inhibitors of DNA synthesis, however, seem to prevent the appearance of late mRNA only in cells transformed by SV40 and not in infected cells.