Antennal sensory organs in the millipede Eurypauropus ornatus: Fine structure of the flagella and globulus

On the antennal tip of Eurypauropus ornatus are 3 threadlike sensilla—the flagella, and a single spheroid sensillum—the globulus. Each of the 3 flagella is innervated by 2 groups of sensory cells. One group contains 4 cells, the other, 5. All cells of the “four group” and 3 of the “five group” are comprised of single cilia and unbranched dendrites which extend along the lumen of the flagellum. Two cells of the “five group” have double cilia and pairs of unbranched dendrites. One pair also enters the flagellum and the other pair terminates beneath the flagellar base to form a concentric array of lamellae. No pores are present in the cuticular wall. Eight sensory cells innervate the globulus. They are arranged in 3 groups, one triplet and 2 pairs, in addition to a single cell. The single cell contains a pair of cilia whose unbranched dendrites differentiate into tubular bodies that are inserted into the base of the globulus. Each of the other 7 sensory cells has a single cilium. Their unbranched dendrites penetrate into the globulus in 3 groups as described for the sensory cells. The dendrites in each group terminate in an individual pore channel at the globulus tip and completely fuse with the electron-dense material that plugs the pore channel. Based on structural similarities to sensilla having known functions, it is probable that the flagella and the globulus are chemoreceptors, the former responding to odors, the latter sensitive to substances in aqueous solution.     

Sexual differentiation in Mucor: Trisporic acid response mutants and mutants blocked in zygospore development

Spores of a minus strain of Mucor mucedo (Bref.) were treated with 1-methyl-[3-nitro]-1-nitro-soguanidine and mutants were isolated either by testing for zygophore induction with externally supplied trisporic acids (TA) or by mating with wild type plus colonies. Mutants were found defective (Tar^?) or temperature-sensitive (Tar-Ts) in their reaction towards trisporic acids, blocked or temperature-sensitive in their mating with plus strain (Mat^? or Mat-Ts) or temperature-sensitive in zygospore development (Zyg-Ts). The inability to react against externally supplied trisporic acids was not necessarily coupled with an inability to mate with plus strain (phenotype Tar^? Mat⁺). This indicated that the diffusion and uptake of trisporic acids is not a necessary prerequisite to the sexual interaction of Mucor mating types.     

Hygroreceptor identification and response characteristics in the stick insectCarausius morosus

Summary Simultaneous recordings were made from 3 sensory units in an easily identifiable sensillum on the 12th antennal segment ofCarausius morosus. Impulse frequency (F) of one unit rose sharply when either the temperature (T) or the partial pressure of water vapor (Pw) was suddenly lowered. F of another rose sharply either when T was suddenly lowered or Pw was raised. F of the third was hardly affected by sudden changes in T but rose abruptly when Pw fell (Fig. 1). The reactions of the first may be explained by enthalpic cooling and is considered a cold cell. Those of the second may be attributed to changes in relative humidity (Hr) and is thus termed a moist cell. The third is taken to be the latter's antagonist, a dry cell.A 90%-probability that a single moist cell of average differential sensitivity will correctly discriminate between two humidity levels is not reached until the difference between the two is 38% Hr. The dry cell requires a difference of only 7.5% (Table 1). The basis for discrimination is a single presentation of each level.The power to discriminate Hr steps is better in both cell types. For a single moist cell of average differential sensitivity the difference required between the steps for a 90%-probability of correct discrimination is only 6.3% Hr; for the dry cell, 3.5% Hr. Basis for discrimination: a single presentation of each step. Step range: 5% to 55% Hr.Abbreviations F impulse frequency in impulses per second (imp/s) - Hr orHR relative humidity in % - Ps saturation pressure of water vapor in torr - Pw partial pressure of water vapor in torr - r correlation coefficient - T temperature in °C Dedicated to Prof. Dr. F. Schaller on the occasion of his 65th birthday     

Neither an enhancement of autolytic wall degradation nor an inhibition of the incorporation of cell wall material are pre-requisites for penicillin-induced bacteriolysis in staphylococci

In contrast to what has been postulated, penicillin G at its optimal lytic concentration of 0.1 g per ml did not lead to a detectable activation of autolytic wall processes in staphylococci in terms of the release of uniformly labelled wall fragments from cells pretreated with the drug for 1 h. Rather a considerable inhibition of this release was observed. A similarly profound inhibition of the release of peptidoglycan fragments occurred when staphylococci pretreated for 1 h with 0.1 g penicillin per ml acted as a source of crude autolysins on peptidoglycan isolated from labelled normal cells of the same strain. This clearly demonstrated that the overall inhibition of autolytic wall processes caused by penicillin was mainly due to a decreased total autolysin action rather than to an altered wall structure. Furthermore, no substantial penicillin-induced inhibition of the incorporation of ¹⁴C-N-acetylglucosamine into the staphylococcal wall could be observed before bacteriolysis started, i. e., approximately during the first 80 min of penicillin action. These results are not consistent with any of the models hitherto proposed for the action of penicillin.Dedicated to Prof. Dr. Gerhart Drews on the occasion of his 60th birthday     

A novel, “hidden” penicillin-induced death of staphylococci at high drug concentration,occurring earlier than murosome-mediated killing processes

In log-phase cells of staphylococci, cultivated under high, non-lytic concentrations of penicillin G, there occurred a novel killing process hitherto hidden behind seemingly bacteriostatic effects. Two events are essential for the apprearance of this hidden death: (i) the failure of the dividing cell to deposit enough fibrillar cross-wall material to be welded together, and (ii) a premature ripping up of incomplete cross walls along their splitting system. Hidden death started as early as 10–15 min after drug addition, already during the first division cycle. It was the consequence of a loss of cytoplasmic constituents which erupted through peripheral slit-like openings in the incomplete cross walls. The loss resulted either in more or less empty cells or in cell shrinkage. These destructions could be prevented by raising the external osmotic pressure. In contrast, the conventional non-hidden death occurred only much later and exclusively during the second division cycle and mainly in those dividing cells, whose nascent cross walls of the first division plane had been welded together. These welding processes at nascent cross walls, resulting in tough connecting bridges between presumptive individual cells, were considered as a morphogenetic tool which protects the cells, so that they can resist the otherwise fatal penicillin-induced damages for at least an additional generation time (morphogenetic resistance system). Such welded cells, in the virtual absence of underlying cross-wall material, lost cytoplasm and were killed via ejection through pore-like wall openings or via explosions in the second division plane and after liberation of their murosomes, as it was the case in the presence of low, lytic concentrations of penicillin. Bacteriolysis did not cause any of the hitherto known penicillin-induced killing processes.Dedicated to Prof. Dr. Georg Henneberg on the occasion of his 85th birthday     

Evidence for the Existence of Differential O-Glycosylated α5-Subunits of the γ-Aminobutyric AcidA Receptor in the Rat Brain

Abstract: Polyclonal antibodies were raised to synthetic peptides having amino acid sequences corresponding with the N- or C-terminal part of the γ-aminobutyric acid_A (GABA_A) receptor α₅-subunit. These anti-peptide α₅(2–10) or anti-peptide α₅(427–433) antibodies reacted specifically with GABA_A receptors purified from the brains of 5–10-day-old rats in an enzyme-linked immunosorbent assay and were able to dose-dependently immunoprecipitate up to 6.3 or 13.1% of the GABA_A receptors present in the incubation, respectively. In immunoblots, each of these antibodies reacted with the same two protein bands with apparent molecular mass of 53 or 57 kDa. After exhaustive treatment of purified GABA_A receptors with N -Glycanase, each of these antibodies identified two proteins with apparent molecular masses of 46 and 48 kDa. Additional treatment of GABA_A receptors with neuraminidase and O -Glycanase resulted in an apparently single protein with molecular mass of 47 kDa, which again was identified by both the anti-peptide α₅(2–10) and the anti-peptide α₅(427–433) antibody. These results indicate the existence of at least two different α₅-sub-units of the GABA_A receptor that differ in their carbohydrate content. In contrast to other α- or β-subunits of GABA_A receptors so far investigated, at least one of these two α₅-subunits contains O-linked carbohydrates.     

Die postembryonale Entwicklung und die funktionelle Anatomie des Gnathosoma in der Milbenfamilie Erythraeidae (Acarina,Prostigmata)

Zusammenfassung Das Gnathosoma von sieben Arten der Milbenfamilie Erythraeidae wurde untersucht. Die postembryonale Entwicklung der Cuticula-Strukturen, der Muskulatur und der Drüsen wird beschrieben.Das Gnathosoma der Larven weist Cheliceren auf, die aus Grundglied und klauenförmigem Digitus mobilis bestehen. Sie liegen dem Infracapitulum dorsal auf und inserieren an einem Paar Capitular-Apophysen. Bei den Protound Tritonymphen unterliegt das Gnathosoma der Histolyse und wird anschließend jeweils neu ausgebildet. Bei der Deutonymphe und beim Adultus ist es gegenüber der Larve stark abgewandelt: Die Tracheenstämme sind aus den Capitular-Apophysen der Larve abzuleiten. Die Stech-Cheliceren entsprechen dem Grundglied der larvalen Cheliceren, und ihre medialen Protraktoren gehen aus den Levator-Muskeln der Cheliceren der Larve hervor.Der Weg der Sekrete der podocephalischen und infracapitulären Drüsen über die Dorsalfläche des Infracapitulum erfährt mit dem Erwerb schmaler Stech-Cheliceren eine radikale Umstellung des Schutzes gegen Austrocknung. Während bei der Larve die breiten Cheliceren-Grundglieder den Sekretweg überdecken, und der Raum zwischen den Grundgliedern und dem Infracapi-tulum zusätzlich durch das ölartige Sekret der Intercheliceraldrüse ausgefüllt wird, schließen sich bei der Deutonymphe und beim Adultus die Lateralkiele der Genae über den Stech-Cheliceren zusammen, und der hintere Abschnitt des Cervix wird in das Idiosoma eingesenkt. Dadurch wird der Cervix zu einem internen Cervicalkanal umgebildet.Der Mundraum wird bei den aktiven Stadien durch die lipidartigen Sekrete der Buccal- und Labialdrüsen geschützt.Die phylogenetischen Beziehungen der Parasitengona innerhalb der Prostigmata und der Erythraeidae innerhalb der Parasitengona werden diskutiert.

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Postembryonic development and functional anatomy of the gnathosoma in the family Erythraeidae (Acarina, Prostigmata)

Summary The gnathosoma of seven species of the Erythraeidae was investigated. The postembryonic development of the cuticular structures, the musculature and the glands are described.In the larval gnathosoma, the chelicerae consist of a basal segment and a claw. They rest upon the dorsal surface of the infracapitulum. The basal segments are attached to a pair of capitular apophyses (sigmoid pieces). During the two molts larva to protonymph and deutonymph to tritonymph, the gnathosoma is histolysed. Directly afterwards it is rebuilt. Compared to the larva, in the deutonymph and in the adult it undergoes profound changes: The capitular apophyses are transformed to parts of the tracheae, the basal segment of each chelicera to a styliform chelicera, and the levator muscles of the chelicerae to medial protractors of the styliform chelicerae.The secretions of the podocephalic and infracapitular glands proceed along the dorsal surface of the infracapitulum to the buccal cavity. In the larva, the way of the secretions is protected against desiccation by the broad basal segments of the chelicerae, that cover the infracapitulum. In addition the oily secretion of the intercheliceral gland seals the space between the infracapitulum and the chelicerae. By obtaining styliform chelicerae the protection against desiccation undergoes a radical change: The lateral ridges of the infracapitulum join above the chelicerae, and the posterior part of the cervix is transferred back into the idiosoma. Thus the cervix is transformed into an internal canal.In the active instars, the buccal cavity is protected by the lipid-like secretions of the buccal glands and labial glands.The phylogenetic relationships of the Parasitengona within the Prostigmata, and of the Erythraeidae within the Parasitengona are discussed.

     

Calcium and magnesium levels in isolated cardiac mitochondria from mice injected with isoproterenol

Summary Calcium (Ca) and Magnesium (Mg) are determined by atomic absorption flame spectrometry in isolated cardiac mitochondria from mice receiving subcutaneous injections of DL-isoproterenol HC1 (ISO), and in mitochondria of untreated controls. In the controls, mitochondria were isolated in the presence or absence of ruthenium red. On the absence of ruthenium red in the isolation medium, mitochondrial Ca levels increase by about 300%, while levels of Mg remain unchanged. Focal myocardial necrosis following a single ISO-injection is shown by electron microscopy. Ca and Mg levels are largely unaffected by a single dose of ISO until 24 h after the injection. A slight increase in Ca occurs in the 48 h samples. When multiple injections of ISO are given every 12th hour for 48 h, 72 h and 96 h, respectively, endogenous Ca and Mg increase significantly. It is suggested that this increase might be associated with ISO-induced cardiac hypertrophy rather than with the pharmacological effects of ISO per se.This work was supported by grants from The Norwegian Council on Cardiovascular Disease and from The Norwegian Research Council for Science and the Humanities