Hybrid dysgenesis-induced Y chromosomal sterility in Drosophila melanogaster

Summary Dysgenic hybrids of Drosophila melanogaster were screened for the induction of mutations in the Y chromosomal fertility genes. Out of 2,417 Y chromosomes analysed 13 male steriles (ms (Y)) were isolated. This high rate of mutation is most probably due to the unusually large physical size of the fertility genes.     

Zur anatomie der ammoniten: Tintenbeutel,kiemen, augen

The ink sacs within the living chambers of ammonites as hitherto published seem to be remains of the stomach-crop-complex. Ammonites had no ink sacs. Fossilised remains of gills were found within the living chambers of three ammonoid specimens (generaOphiceras, Hildoceras, Eleganticeras). Their state of preservation is not good enough to identify their numbers. Their shape seems to be not quite dissimilar to that of recentNautilus. Reflections concerning the eyes of ammonites suggest that they were of the pinhole type like those of recentNautilus.     

Effects of fertilization and liming on the chemical soil conditions and element distribution in forest soils

Summary The distribution and storage of major elements in acid soils from a spruce and a beech forest was investigated after fertilization of NH₄NO₃ and KCl followed by Ca and Mg fertilization by 2 liming applications. All fertilizers were applied on top of the soil without mixing. Most of the added Ca and Mg was detected in the humus layer, a significant part of it still in carbonatic form. The effect of liming on mineral soil pH is very low, and was only observed in the 0–10 cm layer. However, base saturation of the mineral soil increased. The storage of C and N of the humus layer was not affected. N fertilization increased the N storage of the soil only under beech, but was followed by heavy NO₃-losses with seepage water under spruce. High leaching rates for K were also found in the spruce stand. The amount of K that was not leached increased the pool of exchangeable K in the deeper soil layer.     

The effects of cytotropic compounds on the resialylation of human asialotransferrin type 3 in the rat

Effects of chloroquine, colchicine, leupeptin, taxol and vinblastine on the resialylation and degradation of human [125I]asialotransferrin type 3 were studied in rats. An improved experimental technique was applied that permitted the quantification of resialylated ligand produced by individual animals over 3 h by using deconvolution. All three microtubule inhibitors increased the proportion of the dose undergoing resialylation by 35-39%. In addition, colchicine, and, especially, vinblastine enhanced the overall recovery of the dose as protein-bound 125I. The dose recovery was also augmented by leupeptin without any concomitant change in resialylation. Chloroquine suppressed resialylation and this effect could only be partially lifted by the administration of colchicine. The blood of colchicine-treated rats possessed no resialylating activity toward the ligand even when supplemented with additional alkaloid in vitro. The observations support the view that the respective fractions of the ligand destined for resialylation and degradation can, to a certain extent, be varied independently of each other. The effects of short-term starvation (20 h) and refeeding (4 h) on these processes are also presented.     

Fluorescence methods for localizing proteinases and proteinase inhibitors in skeletal muscle

Summary Proteinases and proteinase inhibitors have become suspect in a wide variety of muscle wasting conditions that might be treatable if knowledge of the cellular locale and function of these molecules were known. Fluorescent probes have been useful in the localization of proteinases in muscle samples from human and animal specimens. These include the histochemical localization of proteinases based on the specific fluorescence of hydrolysis product derivatives, but this approach has been limited to the lysosomal proteinases because of the acidic requirements of the trapping reaction of the primary reaction product. Immunohistochemical techniques do not have the same restrictions and a number of lysosomal and nonlysosomal proteinases have been identified in muscle by this means. Unfortunately, they do not yield any information as to the activity of the enzymes. This is an important consideration since the extracellular environment contains a number of proteinase inhibitors, some of which may be internalized by the cell.     

Determination of the hydraulic conductivity of Lamprothamnium by use of the pressure clamp

By use of the pressure-clamp technique, the hydraulic conductivity of the brackish-water alga Lamprothamnium was found to be 5·10^-6 cm s^-1 bar^-1. The dimensions of the internodes are so small that it is possible, for the first time, to measure a complete volume relaxation upon clamping the turgor pressure to a preset value by a feedback control of the pressure probe. As theoretically predicted, the values of the hydraulic conductivity obtained from the initial slope of the volume relaxation induced by the pressure clamp are in agreement (within experimental error) with those obtained from the half-time of the relaxation process. The cell volume also obtained from the analysis of the volume relaxation is the osmotically effective cell volume and is therefore slightly smaller than the value obtained by taking the dimensions of the cell including the cell wall.Abbreviations and symbols Lp hydraulic conductivity - P turgor pressure - S_v initial slope of volume relaxion - T_1/2 half-time of volume relaxation Dedicated to Professor Dr. H. Ziegler on the occasion of his 60th birthday     

Isolation and characterization of a new thermophilic and autotrophic methane producing bacterium:Methanobacterium thermoaggregans spec. nov.

Methanobacterium thermoaggregans is a new thermophilic autotrophic rod-shaped methane producing bacterium. The organism likes to form aggregates during growth and utilizes only H₂ and CO₂ as substrates. Growth optimum is at 65°C with a doubling time of 3.5 h. Optimal growth occurs at pH-values between 7 and 7.5. The addition of yeast extract to the mineral salt medium stimulates growth. The DNA base composition is 42 mol% G+C. The organism was isolated from mud taken from a cattle pasture. Because of its optimal growth temperature and its tendency to form aggregates the nameMethanobacterium thermoaggregans is suggested.Abbreviations G+C Guanine+cytosine     

On the fine structure of the cerebral ganglion of Sagitta (Chaetognatha)

Summary In this study the fine structure of the cerebral ganglion of Sagitta setosa (Chaetognatha) is investigated. The ganglion is flat and superficially positioned dorsally, below the basal lamina of the cephalic epidermis. It is surrounded by a specifically differentiated sheath. This sheath is made up of cells, which are interpreted as representing glial cells, and can be divided into an outer and an inner zone. The outer zone is composed of flat sheath cells with pale nuclei and few organelles. The inner zone consists of densely packed, extremely thin lamellar cellular processes. These attenuated lamellae, which still contain cytoplasm, resemble the myelin sheath of vertebrate axons. The intercellular space between the lamellae contains electron-dense material. In the sheath specialized intercellular contacts occur. The inner zone of this sheath extends at definite points into the centre of the ganglion and separates a zone of perikarya from the neuropil, as well as the single perikarya from each other. The perikarya are relatively uniform and do not form a cortex, but are concentrated mainly in lateral parts of the cerebral ganglion. Within the neuropil are axonal endings which have synaptic contacts with several postsynaptic elements. These anatomical findings are discussed with respect to their functional significance.     

Regional differences in a nematoceran retina (Insecta,Diptera)

Summary The compound eye of Psychoda cinerea comprises two types of ommatidia, arranged so as to divide the retina into distinct dorsal and ventral regions. The P-type ommatidium, in the ventral part of the eye, differs fundamentally from the other dipteran ommatidia so far described, and is regarded as a primitive ommatidium. The acone dioptric apparatus is the same in both types, with a spherical lens and four Semper cells, the processes of which expand below the rhabdom to form a ring of pigment sacs. Only the distal region of the rhabdom is surrounded by a continuous ring of screening pigment, formed by 2 primary and 12–16 secondary pigment cells. The highly pigmented retinula cells penetrate the basement membrane proximally at about the level of their nuclei; in this region they are separated from the hemolymph by glial elements. The rhabdomeres R1–6 are fused to form a tube. The two types of ommatidia are defined by the arrangement of the retinula cells R7/8: in the T type the central rhabdomeres are one below the other, in the usual tandem position, whereas in the P type only R8 is central, with R7 in the peripheral ring. In the proximal region of the retina, retinula cells with parallel microvilli in neighboring ommatidia are joined in rows by lateral processes from the R8 cells. All the rhabdomeres are short and not twisted, which suggests that the retinula cells are highly sensitive to direction of polarization. The eye can adapt by a number of retinomotor processes. These findings, together with observations of behavior, imply that the psychodids have well-developed visual abilities.