Fate of spermatozoa that do not participate in fertilization in the domestic fowl

Summary The fate of spermatozoa that do not participate in fertilization was investigated by electron microscopy. After artificial insemination, we observed several spermatozoa between the fibers of the outer layer of the vitelline membrane of the ovum. One or more spermatozoa were also found in a phagocytic vesicle of macrophages located in the intercellular space of the mucosal epithelium of the infundibulum or in the outer layer of the vitelline membrane.From these observations, we assume that the superfluous spermatozoa in the lumen of the anterior part of the oviduct might be removed by inclusion into the outer layer of the vitelline membrane and by phagocytosis by macrophages.The authors are greatly indebted to Assoc. Prof. Osamu Koga for his invaluable advice. The authors also wish to thank Mr. Takayuki Mri for his helpful suggestions and technical advice. This investigation was supported by a grant from the Ministry of Education of Japan (156185)     

The structure and distribution of satellite cells of cardiac muscles in decapod crustaceans

Summary The structure and distribution of satellite cells of cardiac muscles were examined in twenty-one species of animals chosen from each tribe within the order Decapoda (Arthropoda, Crustacea). The satellite cells were found in all animals observed. Most of them are morphologically identical with those described in different striated muscles of other species, but some cells have unusual features. The decapod satellite cell occasionally lies right over the region corresponding to the intercalated disc between the apposed cardiac muscle cells. The cell sends cytoplasmic processes into the adjacent muscle cells, enabling the plasma membrane to make close contact with the cleft opening of the intercalated disc, and with the myofibril at the level of the Z-line. Another characteristic feature is the presence of paired cells. Such cells are clearly separated from each other over most of the contact area by the respective plasma membranes, which are smooth in appearance and devoid of specialized regions. The significance of the presence of satellite cells in decapod cardiac muscle and its possible role are discussed and compared with those described for other species.     

On the yolk sac of the cat

Summary The phase of primitive erythropoiesis in the feline yolk sac lasts from the 14th to the 20th day after mating. The globular nucleated primitive erythroblasts are formed extravascularly to some extent, but they can be clearly distinguished from the endoderm. They do not undergo a denucleation and are still present in the circulating blood on the 45th day. Aging primitive erythroblasts are characterized by a loss of polysomes, by the appearance of long intracytoplasmic electron-lucent channels, and by a nuclear pyknosis which can turn into a karyolysis. Definitive erythropoiesis begins around the 17th day but, even by the 19th day, it is not particularly prominent. It ends around the 45th day. It is almost exclusively intravascular. The distinction of immature primitive erythroblasts from erythroblasts of the definitive series is difficult, because it is based upon only slight differences in the heterochromatinization, in the nuclear-cytoplasmic ratio, and in the organelle content of the cells. In the definitive series, the nuclear divisions follows the law of the rhythmical halving of the nuclear volume. The cells exhibit more clearly identifiable maturation stages here, and the checkerboard nucleus is more distinct. The vascular endothelium is largely attenuated and moderately fenestrated; it lacks a distinct basement membrane. Organelle-rich adventitial cells are found in close apposition.     

Septate junctions in the cephalic epidermis of turbellarians (Bipalium)

Summary In the epidermis of turbellarians septate junctions of the pleated sheet type have been demonstrated in conventional thin sections and freeze fractured preparations. The structure of these junctions entirely agrees with that found in molluscs and arthropods.Financially supported by DFG (Sto 75/3,4; We 380/5)     

Verstärkung der antiphytoviralen Wirkung von 2,4-Dioxohexahydro-l,3,5-triazin durch Kombination mit Verbindungen mit Guanidinstruktur

Intensified antiphytoviral activity of 2,4-dioxohexahydro-l,3,5-triazine by combination with guanidines Combined application of the antiphytoviral compound 2,4-dioxohexahydro-l,3,5 triazine (DHT) and different guanidines (GDs) that were either unsubstituted or substituted only by low-molecular substituents reduced the concentration of potato virus χ (PVX) in leaves or Nicotiana tabacum L. cv. Samsun much more than application of either agent alone. In secondarily PVX-infected leaves, the activity of 2,4-dioxohexahydro- 1,3,5-triazine was increased by a larger number of GDs and to a greater degree than in inoculated ones. The activities of GDs against tobacco mosaic virus (TMV) in Nicotiana tabacum L. cv. Samsun as well as against brome grass mosaic virus (BRV) in Hordeum vulgare L. cv Vogelsanger Gold were only insignificantly increased by combination with DHT. On the other hand, in experiments with so-called identical potato eye cuttings, in which several eye cuttings were obtained from each potato tuber, one serving as a control and the others being treated with DHT, N-cyano guanidine or a combination of these substances, the number of cuttings with symptoms of potato leaf-roll virus (PLRV) could be much more greatly reduced by the combination than by the individual preparations. The number of cuttings with symptoms of potato virus Y and potato virus A was significantly reduced by treatment with the combined preparation, but not by treatment with DHT or N-cyano guanidine alone. Additional investigation with N-cyano-GD, and, beside this, with acetyl-GD and N N′ N triamino-GD indicated a close correlation between the diminution of numbers of potato eye cuttings with virus symptoms and the increase in tuber weight. The greater the reduction in the number of cuttings showing virus symptoms, the greater was the increase in tuber weight. These relationships were observed even in those cases where controls had been treated with ammonium nitrate solutions whose N contents equivalent to the N contents of the preparations. The observed effects of the preparations therefore are not attributable to N-fertilizing effects.     

Quaternary structure of ATP synthases: Symmetry and asymmetry in the F1 moiety

It has been proposed that during ATP synthesis/hydrolysis F₁ ATPases experience a complex pattern of nucleotide binding and release during the catalytic cycle (binding change mechanism). This type of mechanism has implications that can be correlated with the structure of the enzyme. F₁-ATPases (stoichiometry ₃₃) are essentially a symmetrical trimer of pairs of the major subunits ( and ); the minor subunits (, and ) are in single copies and interact with the trimer in an asymmetrical fashion. The asymmetry introduced by the minor subunits has important structural and functional consequences: (1) it introduces differences between the potentially equivalent binding and catalytic sites in the major subunits, (2) it restricts the ways in which a binding change mechanism can occur, and (3) it governs the way in which the F₁ interacts with the (asymmetrical) F₀ sector.     

Aldosterone regulation of active sodium chloride transport in the lizard colon (Gallotia galloti)

Summary Bioelectrical parameters and unidirectional sodium and chloride fluxes were measured under voltageclamp conditions in groups of lizards submitted to single or chronic aldosterone treatment. Both acute (AT) and chronic (CT) treatment induced significant increases in the short-circuit current (I _sc), as well as in the mucosa-to-serosa (J _m-s ^Na ) and net sodium flux (J _net ^Na ). In AT tissues, aldosterone did not change net chloride flux (J _net ^Cl ) but did so in CT tissues. Amiloride reduced the aldosterone-increased I _sc in AT and CT tissues, inhibited J _net ^Na in AT tissues and abolished it in CT colons. J _net ^Cl was also reduced by the diuretic in the group of AT colons, whereas no changes were observed in the CT tissues. Addition of luminal DIDS reduced Na⁺ absorption and totally inhibited Cl^- absorption in the AT tissues, but did not change I _sc. However, in CT tissues neither Na⁺ nor Cl^- transport were affected by DIDS. A good relationship between I _sc and J _m-s ^Na was apparent after DIDS treatment in AT tissues. In this group, simultaneous addition of DIDS and amiloride totally abolished J _net ^Na and reduced I _sc to untreated control values. Addition of serosal ouabain abolished I _sc and Na⁺ absorption in AT and CT colons, but Cl^- absorption was only altered in AT tissues. These results support the hypothesis that aldosterone induces an electrogenic, amiloride-sensitive sodium absorption, and in a dose-dependent fashion suppresses electroneutral NaCl absorption in the lizard colon.Abbreviations AT acutely treated - CT chronically treated animals - DIDS 4-4-diisothiocyanatostibene-2-2-disulfonic acid - DMSO dimethylsulphoxide - G _t tissue conductance - I _sc short circuit current - PD transepithelial potential difference - SITS 4-acetamido-4-isothiocyanatostilbene-2-2-disulfonic acid - UC untreated controls Preliminary results of this paper were presented at the X ^th meeting of the European Intestinal Transport Group (EITG), Askov Hojskole, Denmark, 16–19 September 1990     

Fine structural studies on the reabsorption of colloid and fusion of colloid droplets in thyroid glands of TSH-treated mice

Summary The mechanism of the luminal colloid reabsorption and the fate of reabsorbed colloid droplets were studied ultracytochemically in epithelial cells of thyroid cells of TSH-treated mice. The luminal colloid is reabsorbed by micropinocytosis as well as phagocytosis into the follicle epithelial cell. Almost all the pinocytotic pits and vesicles are coated and often closely associated with actin filaments demonstrated by use of heavy meromyosin (HMM). This suggests the involvement of the actin filament system in making and transporting coated vesicles for micropinocytosis of the luminal colloid. Freeze-fracture images show aggregates of intramembrane particles on the P-face of the small depressions corresponding to the initial site for coated pits.The reabsorbed colloid droplets fuse with one another and with lysosomes. At the initial stage of this fusion, the limiting membranes of adjoining droplets fuse in a limited area to become pentalaminar, and then become trilaminar. Eventually, the membranes at the fusion point disappear, and the contents of both droplets become continuous. Freeze-fracture images reveal the disappearance of the intramembrane particles at the initial site where the fusion occurs.Examination of thin-sectioned tissue treated by rapid-freeze substitution fixation, shows clearly delineated cell organelles, and the rounded mitochondria have a characteristically high electron-dense matrix. Just beneath the limiting membrane of each colloid droplet, there always exists a low electron-dense layer about 10 nm thickness. The lysosomes are sometimes seen wrapped around the colloid droplet.This study was supported by grants (No. 56370002, No. 00544016) from the Japan Ministry of Education     

On the phospholipid metabolism of glial cell primary cultures

Primary cultures prepared from newborn rat brain, consisted after 16 or 17 days mainly of astrocytes and of oligodendrocytes. 1-Alkenyl-sn-glycero-3-phosphoethanolamine (lysoplasmalogen) was used as substrate for studies on the metabolism of ethanolamine-glycerophospholipids. After 3 hr incubation two main products were observed: a) 1-alkenyl-2-acyl-sn-glycero-3-phosphoethanolamine (=ethanolamine plasmalogen) and b) 1-alkenyl-2-acyl-sn-glycero-3-phosphocholine (=choline plasmalogen). The acylation rate reached saturation at about 10 nmol substrate/mg cell protein with aV _max of 30 nmol×mg cell protein^–1×3 hr^–1. This acylated compound amounted to almost 60% of all radioactivity internalized, whereas the second product, choline plasmalogen, came to 20%. Unchanged substrate was found within the cells only in small amounts, even at maximum substrate internalization. These results were discussed in comparison with those obtained with 1-alkyl-sn-glycero-3-phosphoethanolamine under the same conditions (25).     

Structural regularities in tetraether lipids of Caldariella and their biosynthetic and phyletic implications

Individual di(biphytanyl) diglycerol tetraether lipids from thermoacidophile archaebacteria of the Caldariella series, with differently cyclized biphytanyl components, are separated and shown to have structures 8–12, with the glycerol and biphytanyl components demonstrably both antiparallel and with partial assignments of stereochemistry. Tetraethers with alternative arrangements of the components are absent. The structures allow previous observations on these and related lipids to be rationalized both biosynthetically and phyletically.