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At least 433 records · Page 24Linked to original sources
PubMed1976

Conditional spore cortex-less mutants of Bacillus sphaericus 9602.

Lysine-requiring mutants of Bacillus sphaericus 9602 were isolated and classified into three groups by their mutation site in the pathway of lysine biosynthesis. The Group I mutant lacks meso-alpha, epsilon-diaminopimelic acid (meso-Dap) decarboxylase activity, but Group II and III mutants have a normal level of Dap decarboxylase activity. A Group II mutant makes dipicolinic acid from an intermediate in the lysine pathway, but Group III mutants do not. In the absence of meso-Dap in the culture, muramic lactam content in the spore cortex of Group II and III mutants is very low, compared to the wild type content. Addition of meso-Dap to the culture causes an increase of muramic lactam content. Since meso-Dap is detectable only in the spore cortex of B. sphaericus 9602, almost all of the muramic lactam in the spore is probably also located in the cortex. Group I mutants grown in the presence of L-lysine sporulate normally. Group II and III mutants produce oval and nonrefractile spores under the same conditions but the addition of meso-Dap to the culture results in the production of round and refractile spores. Thus, the presence of cortex in the spore is essential to give the round and refractile spores in B. sphaericus. The presence of cortex is also required for the accumulation of dipicolinic acid in the sporulating cells. Furthermore, 1-octanol resistance of the spore depends only on the presence of cortex but both cortex and dipicolinic acid are required for heat resistance of the spore.

Bacillus↗
PubMed1976

Ultrastructure of lymphocyte tumor cell interaction with localization of cell-bound antibody by ferritin labeling.

Splenic lymphocytes derived from Walker carcinoma-bearing rats were harvested and incubated with Walker carcinoma cells growing in tissue culture. The sequence of events leading to target cell death was studied by phase microscopy and scanning and transmission electron microscopy. The sensitized lymphocytes adhere to the tumor cells by multiple cytoplasmic appendages, but no ultrastructural changes are seen at this interface. After 1 hr these lymphocytes release cytoplasmic components consisting of membrane-lined vesicles, cell membranes, endoplasmic reticulum, and cytoplasmic material. This material adheres closely to the surface of the tumor cells and is subsequently seen within the cytoplasm of the tumor cell. The tumor cells then undergo degenerative changes and cell death occurs in 24 to 36 hr. The lymphocyte-derived material appears to contain immunoglobulin components as determined by specific ferritin labeling.

Animals↗
PubMed1976

Scanning electron microscopy of surface features of hamster embryo cells transformed in vitro by X-irradiation.

Scanning electron microscope studies were carried out on Syrian hamster embryo cells transformed in vitro by X-irradiation (300 rads) (X-ray transformed) and on normal nonirradiated and irradiated nontransformed controls. Transformed cells appeared in scanning electron microscopy as pleomorphic, thick cells piling up over each other and exhibiting extensive surface features consisting of microvilli, blebs, and ruffles. These surface structures were seen on single as well as on densely cultured transformed cells during both interphase and mitosis. The complex surface was observed shortly after transformation (on cells of a 20-day-old clone) and seems a permanent feature of the X-ray-transformed cells (present after 8 years in culture). All controls appeared by scanning electron microscopy as regular, flat, and smooth cells which grew in high-density cultures to seemingly contact-inhibited monolayers. During mitosis the normal cells (control, nontransformed) displayed surface excrescences similar to those of the transformed cells making the mitotic normal cells indistinguishable from transformed cells. The complex surface features in the normal cells were temporary and reversed back to characteristic smoothness upon reentrance into interphase.

Agglutination↗
PubMed1976

Utilization of exogenous GDP-mannose for the synthesis of mannose-containing lipids and glycoproteins by oviduct cells.

Suspensions of oviduct cells were prepared by subjecting oviduct tissue to sequential incubations with EDTA, alpha-chymotrypsin, and crude collagenase, followed by a final incubation with EDTA. Cells isolated in this way incorporate mannose from exogenous GDP-mannose into mannosyl-lipid, oligosaccharide-lipid, and glycoprotein(s). Based on several criteria, the mannosyl-lipid is identical with mannosyl-phosphoryldolichol. Similarly, the oligosaccharide-lipid appears to be identical with the oligosaccharide-lipid synthesized in vitro (Lucas, J. J., Waechter, C. J., and Lennarz, W. J. (1975) J. Biol. Chem. 250, 1992-2002). In contrast, the glycoproteins are much lower in molecular weight than those labeled in cell-free preparations. Using intact oviduct cell suspensions it was found that: (a) exogenous GDP-mannose, not its breakdown products, serves as the direct mannosyl donor; (b) experiments using mixtures of known proportions of broken and intact cells, as well as studies with metabolic inhibitors, indicate that greater than 50% of the observed incorporation of mannose from GDP-mannose was catalyzed by enzymes associated with intact cells, rather than broken cells or membrane fragments; (c) incorporation of mannose from GDP-mannose into the mannosyl acceptors does not require energy and proceeds without significant uptake of GDP-mannose into trichloroacetic acid-soluble components of the cells; (d) under conditions where labeled guanosine incorporation into nucleic acids is readily detected, no incorporation of the guanosine moiety of [3H]GDP-mannose is observed. These results indicate that the enzymes catalyzing synthesis of lipid-linked intermediates involved in glycoprotein synthesis are not only associated with intracellular membranes, but with the plasma membrane as well.

Animals↗
PubMed1976

[Balantidium coli infection of the female genitals (author's transl)].

Two cases of therapy-resistant fluorine are reported in which Balantidium coli from the class of the cilia (Ciliophora, Ciliata, Infusoria) was identified. After a personal experiment, the Balantidia must be considered extremely pathogenic. In international literature, no further indication of a ciliata infection of the female genitals was found.

Adult↗
PubMed1976

[Findings and significance of spermatozoa agglomeration in the semen].

Agglomeration of spermatozoa (pseudo-autagglutination, clumping of spermatozoa) is distinguished from agglutination in immunological processes by the coarse meshwork of the spermatozoa clumps and the central inclusion of epithelia, leukocytes, residual bodies, spermatozoa with persisting cytoplasmatic droplets, as well as parts of viscous seminal plasma. In 658 semen samples of out-patients with barried marriage, spermatozoa agglomerations were seen in 13.4% of the samples immediately after liquefaction while in additional 6.7%, they were found up to three hours later. The agglomeration phenomenon is typical but not specific of the so-called vegetative congestion syndrome, appearing concomitant with high spermatozoa counts, normal rate of spermatozoa motility and morphology, as well as an increase in residual bodies and spermatozoa with persisting cytoplasmatic droplets. Next to congestion syndrome, spermatozoa agglomerations may also result from post-inflammatory disturbances of epididymal or accessory gland function whereas in florid stages of inflammation, they are rarely observed. As the congestion syndrome may give rise to male infertility in some cases, andrologists should be acquainted with its clinical and spermatological symptoms with special regard to therapy.

Chronic Disease↗
PubMed1976

Absorption of cholesterol by the gallbladder.

To study whether cholesterol is absorbed by the gallbladder, we instilled from 1 to 300 nmoles of [4-14C]cholesterol dissolved in 1 ml of guinea pig bile into the in situ guinea pig gallbladder. The bile used in these experiments contained 7 mumole/ml bile acid, 27 nmole/ml lecithin, and 8 nmol/ml cholesterol. To this bile, we added the radioactive cholesterol, from 0 to 1 mumole/ml egg lecithin, and 100 mug/ml of bromosulfophthalein, a nonabsorbable marker. After 1 nmole [4-14C]cholesterol was instilled in bile without added lecithin, 77 +/- 8% of the radioactivity was demonstrated to be in the gallbladder wall 6 hours later. The proportion of cholesterol absorbed by the gallbladder decreased as the concentration of added lecithin or bile salts was increased. Radioautography showed radioactivity in the mucosa, and subcellular fractionation of homogenized cells by centrifugation showed cholesterol in the mitochondrial (23 +/- 4%) and microsomal (18 +/- 4%) fractions. Studies on specific activity suggested that there was net absorption of cholesterol and not merely an exchange of cholesterol in the contents for cholesterol in the wall. This study presents evidence that significant quantities of cholesterol but not cholesterol ester can be absorbed by the guinea pig gallbladder. We also found that the absorbed cholesterol can be converted to cholesterol ester and the relevance of these findings to cholesterosis in man are discussed.

Animals↗
PubMed1976

The formation of the gonadal ridge in Xenopus laevis. III. The behaviour of isolated primordial germ cells in vitro.

Previous studies have described the morphology, including the ultrastructure, of primordial germ cells (PGCs), and the cells with which they associate to form the gonadal ridge, in Xenopus laevis. In order to test their capacity for active movement we have studied single, isolated PGCs in vitro. Time-lapse studies of these cells reveal that they are motile, using broad cytoplasmic processes. The fact that these cells are very large and easy to manipulate in vitro makes them an attractive subject of study, particularly with respect to the mechanism of their movement and the surface phenomena which guide them to the site of the gonadal ridge.

Animals↗
PubMed1978

[Morphological virus diagnosis--electron microscopy study of animal viruses with negative contrast procedure].

Reported in this paper are results obtained in morphological virus diagnosis by using the negative contrast technique on the basis of electron microscopy. The availability of high-efficiency electron microscopy as well as of perfectly improved techniques of preparation, knowledge of the latest virus model concepts, and indivudual skills in diagnosis are essential conditions for the above approach. Parvoviridae, picornaviridae, and togaviridae are identifiable only in high particle concentrations and by group representation. Papovaviridae, adenoviridae, herpetoviridae, poxviridae, and reoviridae, on the other hand, can be safely identified even as single particles. The diagnosis of orthomyxoviridae, paramyxoviridae, rhabdoviridae, and retroviridae is facilitated by their own dimensions and their characteristic helico-symmmetrical nucleocapside. Coronaviridae are of highly conspicuous morphology but, nevertheless, pose problems in differential diagnosis. Substantive improvement of morphological virus diagnosis, in terms of minute details, may be achieved by means of the negative contrast method on the basis of immune electron microscopy. Advantages implied in that morphological method include less time-consuming and quite uninvolved practicability and good dependability of diagnosis for more efficient decision-making in research and practice.

Animals↗
PubMed1978

The preparation and ultrastructure of avian erythrocyte nuclear envelope enclosed by the plasma membrane.

A procedure is described for the preparation of avian erythrocyte nuclear envelope ghosts which remain enclosed by the ellipsoid plasma membrane. Haemoglobin-free nucleated chicken erythrocyte ghosts are treated in a low ionic strength buffer plus heparin which brings about decondensation of the chromatin. This is followed by solubilization of the chromatin by digestion with pancreatic deoxyribonuclease-1. When studied by light microscopy using either phase-contrast or Nomarski interference optics, the ellipsoid plasma membrane is clearly seen to remain with the collapsed nuclear envelope trapped inside. This interpretation is supported by negative-staining electron microscopy using ammonium molybdate, which in addition reveals the presence of the nuclear pore complexes. The suggestion is advanced that structural protection is provided for the fragile nuclear envelope system by the surrounding plasma membrane, which might account for the final nuclear envelope being in the form of relatively intact ghosts with well defined nuclear pore complexes. The nuclear envelope is highly fragmented when the plasma membrane is absent, the nuclear pore complexes showing appreciable breakdown. Thin sectioning supports the results of negative staining and in addition shows the nuclear envelope retained within the plasma membrane to be composed of both inner and outer nuclear membranes, but the nuclear pore complexes are not clearly defined.

Animals↗
PubMed1978

An insect cell line persistently infected with a baculovirus-like particle.

A persistent infection by a baculovirus-like particle was found in the established lepidopteran (Heliothis zea) cell line, IMC-HZ-1. The virus caused CPE in less than 1% of the IMC-HZ-1 cells, as measured by phase-contrast and electron microscopy. Transmission tests showed that four lepidopteran cell lines were susceptible to the persistent virus (designated as IMC-HZ-I-NOV). In inoculated TN-368 cell cultures, 90--100% infection was achieved. The ultrastructure and development of IMC-HZ-I-NOV in cell cultures were similar to known baculoviruses, and it is probable that this persistent virus is a member of the family Baculoviridae. Two lepidopterous species (Estigmene acrea and H. zea) inoculated with IMC-HZ-1-NOV by intrahemocoelic injection and/or per os feeding of larvae were not susceptible.

Cell Line↗