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PubMed1975

Electron scanning microscope studies in pigeon pox virus.

It is evident that the five so-called pigeon pox viruses manifest differences in growth patterns. All produced some interruption in the secretory activity of the allantoic membrane. All produced cytoplasmic bridges and distorted the cellular membranes with protoplasmic loops. Only the Amdal virus strain actively ejected virus particles outside the cell membrane. The other virus strains exhibited this tendency to a lesser degree.

Allantois↗
PubMed1985

Structural alteration of the membrane of erythrocytes infected with Babesia bovis.

Babesia bovis, causative agent of cattle babesiosis, induces characteristic alterations on the membrane of infected erythrocytes. Elliptical protrusions measuring about 320 nm in long axis and about 160 nm in short axis appear on the membrane of infected erythrocytes, both in vitro and in vivo. Freeze-fracture demonstrated alignment of intramembrane particles (IMP) along the long axis of both the P and E faces of the protrusions. The number of IMP on the endoplasmic face increases, but the number of IMP on the protoplasmic face of the protrusions is not statistically altered from that of uninfected erythrocytes. In vitro, there are more protrusions per erythrocyte infected with the virulent form (low passage form) of B. bovis than with the avirulent form (high passage form). This suggests that the number of protrusions which appear on the membrane of infected erythrocytes may have a direct relationship to the virulence of the parasites. These protrusions may be attached to the capillary endothelial cells, which causes fatal cerebral babesiosis.

Animals↗
PubMed1999

Plasmodesmata and plant viruses. A centenary story.

The passage of plant viruses from a cell to adjacent ones remained for a long time an unexplained event. Only during the thirties did Samuel and other plant virologists put forward the hypothesis that the passage occurred through plasmodesmata, i.e. those protoplasmic connections between plant cells described since the late 19th century. A direct relation between viruses and plasmodesmata was first demonstrated by electron microscopy during the late 1960s by Esau and co-workers, and then widely confirmed. The mechanism of the passage was investigated in depth starting from the 1970s, and research received a remarkable impulse after that a well-defined model of plasmodesmata had been obtained thank, in particular, to work of the Robards' and Gunning's groups. In this context, the discovery of the polycystronic functionality of the viral genomes was fundamental. A protein coded by tobacco mosaic virus, discovered in 1982 independently by the Soviet group of Atabekov and the American group of Zaitlin, was demonstrated to be indispensable for the transport of virus infection from cell to cell through plasmodesmata. Elegant investigations on this 'movement protein' demonstrated that it actually increases the permeability of plasmodesmata. The relation between viruses and plasmodesmata is one of the most interesting and investigated theme of research, which is receiving much attention from plant virologists, physiologists and molecular biologists. The current status of knowledge still presents unsolved questions, and the story is far from over.

History, 20th Century↗
PubMed1998

Cosmopolitan distribution of the large composite microbial mat spirochete, Spirosymplokos deltaeiberi.

Inocula from organic-rich black muds immediately underlying intertidal laminated microbial mats dominated by Microcoleus chthonoplastes yielded large, variable diameter spirochetes. These unusual spirochetes, previously reported only from the Alfacs Peninsula at the delta of the Ebro river in northeast Spain, contain striking arrays of cytoplasmic granules packed into their protoplasmic cylinders. On several occasions, both in summer and winter, the huge spirochetes were recognized in samples from mats growing in the Sippewissett salt marsh at Woods Hole Massachusetts. They were also seen in similar samples from microbial mats at North Pond, Laguna Figueroa, Baja California Norte, Mexico. The identity of these spirochetes was confirmed by electron microscopy: number and disposition of flagella, composite structure, measurements of their distinctive cytoplasmic granules. The granules, larger, more conspicuous and present in addition to ribosomes, are hypothesized to contain ATPases. As culture conditions worsen, these spirochetes retract into membrane-bounded round bodies in which they form refractile inclusions. From morphology and behavior we conclude the North American spirochetes from both Atlantic and Pacific intertidal microbial mats are indistinguishable from those at the delta of the Ebro river. We conclude a cosmopolitan distribution for Spirosymplokos deltaeiberi.

Massachusetts↗
PubMed1999

[Paul-Louis Simond and coccidia].

In 1880, during a sojourn at Constantine, Alphonse Laveran discovered the etiological agent of human malaria. During his microscopic observations of the parasite in freshly collected blood, Laveran's attention was attracted to the movement of flagellar bodies in the preparations. For Laveran these flagellar bodies corresponded to living organisms, in fact he considered them the most characteristic stage of the parasite; perhaps the sexual form of the parasite. In 1884, back in Paris at the military hospital Val de Grâce, A. Laveran showed these flagellated bodies to Pasteur, Roux and Chamberland who all thought that is was impossible not to recognize a living body in this mass of protoplasm displacing the surrounding red blood cells with its protruding flagella. As early as 1890, Elie Metchnikoff established a link between the flagellar bodies of Laveran and the stealthy stage of parasitic Coccidia infecting the intestinal epithelium of salamanders. It was the Pasteuriens and a few others scientists like Danilewski and Pfeiffer who firmly believed that the flagellar forms were indeed a normal stage during the hematozoan life cycle. On the contrary, Grassi and the Italian school, as well as the French protozoologist Labbé were convinced that the flagellar bodies corresponded to a degenerative form of the parasite provoked by the exposure of the parasites to air during slide preparation. In early 1896, P-L Simond joined Metchnikoff's laboratory and was assigned to study salamander coccidia in order to clarify the nature of the flagellar bodies. In a very short period of time, Simond clearly demonstrated that the coccidia had two types of life cycles; one of which resulted in the formation of flagellar bodies. Simond called the flagellar bodies "chromatozoites" due to the important quantities of chromatin twisted around the flagellum. From these observations and the sperm-like movement of the chromatozoites, Simond put forth the hypothesis that the chromatozoites were the male sexual forms of the parasite. He noted that they were found in all species of coccidia, as well as in the different species of malaria causing hematozoans of man and birds. Simond went even further in his interpretation to suggest that malaria parasites undergo sexual reproduction. This was indeed true, but Simond thought erroneously that sexual reproduction in hematozoans would result in the formation of resistant spores like in the Coccidia. The sexual reproduction hypothesis of malaria parasites was also formulated independently a year later by W. G. MacCallum (1898) working in the United States on Halteridium, a hematozoan infecting crows. Initially MacCallum was not aware of Simond's work, but later gave Simond full credit for his work on Coccidia. Furthermore, MacCallum observed for the first time the chromatozoite (microgamete) enter a female element (macrogamete) to form a mobile worm-like stage of the parasite know today as the ookinete. In his writings Simond is very modest, giving most of the credit to his mentors Metchnikoff and Laveran, but Laveran in an article which appeared in 1899 recognizes P.-L. Simond as the first person having put forth the hypothesis that the flagellar bodies of hematozoans causing human and bird malaria were the male forms of the parasite destined to fertilize the female elements.

Animals↗
PubMed1975

Trehalose and glycogen levels during the initial stages of growth of Candida albicans.

Yeast phase cells of Candida albicans were extracted with cold 0.5 M trichloroacetic acid. The only quantitatively significant anthrone-positive material in these extracts was trehalose which was identified chromatographically and enzymatically. Glycogen in the residue was digested with amyloglucosidase to free glucose which was assayed by a glucose oxidase method. Washed cells from a stationary phase culture of C. albicans rapidly decreased their trehalose content during the early phases of growth on a fresh glucose-containing medium. Concurrent increases in total glycogen concentration were of a greater magnitude than could be accounted for by trehalose mobilization. Thus a specific role for trehalose during initial growth is indicated and is compared with other fungal systems. Trehalase activity was measured in situ and showed only minor changes during the time intervals of these experiments in contrast to other reports on S. cerevisiae. A large fraction of the enzyme in C. albicans behaved as external to the protoplasmic membrane. On one type of growth medium C. albicans exhibited (in addition to trehalose) variable amounts of a sugar alcohol in trichloroacetic acid extracts. This has tentatively been identified as arabitol.

Candida albicans↗
PubMed1975

[The scientific work of W. J. Schmidt (author's transl)].

Ten examples from W. J. Schmidt's workshop illustrate the method of ultrastructural research before the advent of the electron microscope. The consistency is shown with which the research worker W. J. Schmidt pursued his goal, how he succeeded in making fundamental discoveries with his polarizing microscope, and interpreted the results of his indirect structural investigations in such a forward-looking and clearsighted manner that many of them were confirmed by direct reproduction in the electron microscope. This makes W. J. Schmidt one of the great pioneers of ultramicroscopic structural research. He was an extremely prolific writer. His list of publications numbers 404 scientific contributions, three classical books among them. The last of these three monographs was written in 1971; its title is "Polarizing Microscopy in Dental Tissues"; it deals with the ultrastructure of teeth, a subject which never ceased to attract his attention during the more than 50 years of his career as a scientist. It was his intention to write such a textbook on the ultrastructure of teeth during his retirement, a task which he accomplished in spite of the infirmities of old age, thanks to his unbroken will to work. Another characteristic feature of W. J. Schmidt was his extraordinary insistence on complete independence; there are only four among his 404 publications which he wrote, at an advanced age, jointly with Helmut Ruska, and the dental monograph he published in callaboration with A. Keil. Everything else was entirely his own effort. His capacity for work was almost inexhaustible. In 1937, for instance, he published 18 scientific papers, among them his richly illustrated protoplasm monograph of 388 pages. His inflexible will to observe everything personally and to interpret and edit his findings alone was part of his special intellectual constitution. In discussions he stubbornly defended his point view and considered suggestions and new ideas only after he had tested them with his own experiments. This had already become evident at the beginning of his career in a discussion with Ambronn of the nature of birefringence of organized substances. But once he had accepted something as proved he propounded it with persistence and enthusiasm.

Cell Biology↗
PubMed1976

Antibody responses of mice to alkaline detoxifield lipopolysaccharide.

The antibody responses of outbred normal mice and nude mice injected with alkaline detoxified lipopolysaccharide (Alk-LPS) were measured. In some cases the antibody against lipopolysaccharide (LPS) and native protoplasmic polysaccharide (NPP). The kinetics of the primary responses to Alk-LPS and NPP were similar, whereas LPS stimulated a more rapid appearance of antibodies in the primary responses. Alk-LPS stimulated only primary antibody responses in both types of mice and sensitized nude mice for secondary responses which could be triggered with LPS. However, secondary antibody responses could not be triggered in normal mice primed with Alk-LPS. These data suggested that, on a functional basis, Alk-LPS possessed the specific antigenic signal associated with LPS antigens but lack the second nonspecific mitogenic signal dependent on the lipid A portion of LPS.

Alkalies↗
PubMed2001

Localization of endostatin in rat and human gliomas.

BACKGROUND: Endostatin is a potent inhibitor of endothelial cell proliferation, angiogenesis, and tumor growth. Its occurrence and localization has not yet been examined in human brain tumors. The authors report the production of a monoclonal antibody and detection of endostatin in rat and human gliomas by immunohistochemistry. METHODS: The authors analyzed localization and tissue distribution of endostatin in 41 paraffin embedded glioma samples (18 glioblastoma multiforme, 7 WHO Grade III astrocytomas, 13 fibrillary, and 3 protoplasmic WHO Grade II astrocytomas) of human origin and 21 rat C6 gliomas by immunohistochemistry. Double labeling experiments confirmed the origin of endostatin-labeled cells. RESULTS: Endostatin immunoreactivity was detected in tumor cells, endothelial cells, macrophages, and lymphocytes of both rat and human gliomas. The percentage of cells labeled with the endostatin antibody was significantly lower (P = 0.0126) in the tumor parenchyma of human glioblastomas than in WHO Grade II astrocytomas. CONCLUSIONS: Endostatin was present in various cell types in rat and human gliomas in vivo. Lower levels in glioblastomas than in WHO Grade II astrocytomas might have reflected the shift of a probable regulatory balance between promoters and inhibitors of angiogenesis towards facilitation of neovascularization.

Adult↗
PubMedDate not supplied

Physiological differentiation of the mitochondria during Bufo bufo development.

1) The oxygen consumption increases during Bufo bufo development in accordance with the two steps which border at the "heart beat" stage. 2) Cytochrome c oxidase activity is not proportional to the oxygen consumption: it is notable and constant in the first step, and it only increases in the second. 3) In the mitochondria of preneural embryos, citrate synthase, NADP+ dependent isocitrate dehydrogenase, and succinate dehydrogenase activities are very low in respect to malate dehydrogenase and glutamate oxaloacetate transaminase activities. The Krebs cycle results lowered at the condensing reaction level with acetyl accumulation when pyruvate is available. The same behavior has been observed in the Xenopus laevis oocytes and differentiated tissues. 4) The presence of a phosphagen system which is different from creatine phosphate and arginine phosphate, supporting ATP level, has been demonstrated in B. bufo embryos. 5) Mitochondria of postneural embryos are able to accomplish a complete Krebs cycle by increasing citrate synthase, and succinate dehydrogenase activities. 6) In all B. bufo development, malate dehydrogenase and glutamate oxaloacetate transaminase constitute a multienzymatic system by which the mitochondria accomplish a decarboxylic amino acid shunt required for the transformation of deutoplasm into protoplasm. This shunt is also operative in the X. laevis oocytes. 7) Through pyruvate production, by oxidative decarboxylation of malate, the NAD(P)+ dependent malic enzyme could carry out a fundamental anaplerotic function in the mitochondria which is specialized in the production of biosynthetic blocks belonging to the embryo in which the carbohydrates metabolism rather than the glycolytic activity is designed for pentose phosphate and glycerol phosphate synthesis for protein and cytomembrane production. 8) Consistent metabolic differences have been highlighted between B. bufo embryos and X. laevis embryos.

Animals↗
PubMedDate not supplied

[Ultrastructure of the cell surface of heteromorphic Nostoc muscorum CALU 304 cocultured with Rauwolfia tissue].

The ultrastructure of the heteromorphic cells (HMCs) of the cyanobacterium Nostoc muscorum CALU 304 grown in pure culture, monoculture, and a mixed culture with the Rauwolfia callus tissue was studied. The comparative analysis of the cell surface of HMCs, the frequency of the generation of cell forms with defective cell walls (DCWFs), including protoplasts and spheroplasts, and the peculiarities of the cell surface ultrastructure under different growth conditions showed that, in the early terms of mixed incubation, the callus tissue acts to preserve the existing cyanobacterial DCWFs, but begins to promote their formation in the later incubation terms. DCWFs exhibited an integrity of their protoplasm and were metabolically active. It is suggested that structural alterations in the rigid layer of the cell wall may be due to the activation of the murolytic enzymes of cyanobacteria and the profound rearrangement of their peptidoglycan metabolism caused by the Rauwolfia metabolites diffused through the medium. These metabolites may also interfere with the functioning of the universal cell division protein of bacteria, FtsZ. In general, the Rauwolfia callus tissue promoted the unbalanced growth of the cyanobacterium N. muscorum CALU 304 and favored its viability in the mixed culture. The long-term incubation of the Rauwolfia tissue with the N. muscorum CALU 304 cells led to their transformation to L-forms.

Cell Membrane↗
PubMed1998

[Effect on life span and membrane protein in red blood cells by integrated medicine therapy on chronic aplastic anemia].

OBJECTIVE: To explore the mechanism of integrated traditional Chinese and Western medicine (TCM-WM) therapy on chronic aplastic anemia (CAA). METHODS: The RBC life span of 30 normal human subjects and 30 patients with CAA were measured by 51Cr labelled technique before and after TCM-WM therapy. The morphology and distribution of RBC membrane protein granules were observed by freeze fracture etching and transmission electron microscope. RESULTS: The half life of erythrocytes (RBC T1/2) was shortened in CAA cases and there was a significant difference compared to healthy control (P < 0.01). After therapy, the RBC life span prolonged and approached the normal level. Before treatment, there existed abnormal in morphology, decrease in amount and uneven in distribution of protein granules in protoplasmic face (PF) and extracellular face (EF) of RBC membrane. After treatment, the protein granules of RBC membrane was improved and approached to control. CONCLUSIONS: The morphology, amount, quality and distribution of RBC membrane protein granule were closely related to its life span. The therapeutic effect of TCM-WM was better than that of WM alone and it had a function both in stabilizing membrane protein and extending the RBC life span.

Adolescent↗
PubMed1988

Molecular and cellular aspects of calcium action in plants.

Calcium is known to be a second messenger in many developmental processes in animal systems, but it has only recently become evident that Ca is an important intracellular messenger in plants as well. The level of free Ca concentration in the cytoplasm is extremely low, and it is influenced by extracellular signals such as light, gravity, and hormones. Investigations from our laboratory indicated that Ca and its binding protein, calmodulin, play an important role in stimulus-response coupling by regulating enzyme activities, especially through protein phosphorylation. In vivo and in vitro protein phosphorylation studies have revealed Ca-dependent changes in various plant tissues. We have also been able to influence various physiological processes such as cell elongation, abscission, senescence, and tuberization by altering extracellular and intracellular Ca levels. Other examples of Ca-mediated processes in plants are as follows: a) cell division, b) geotropism, c) protoplasmic streaming, d) stomatal control, e) chloroplast movement, f) secretion, g) hormone-dependent changes, h) enzyme activation, and i) protein phosphorylation.

Calcium↗
PubMed1991

Cristispira from oyster styles: complex morphology of large symbiotic spirochetes.

Crystalline styles (digestive organs) of bivalve mollusks provide the habitat for highly motile bacteria. Styles from freshly-collected oysters, Crassostrea virginica, were studied by electron microscopy; Cristispira spirochetes were abundant in these organs. Detailed study reveals these spirochetes to be among the most complex prokaryotic cells known. More than 600 periplasmic flagella and an adhering outer lipoprotein membrane (e.g., a 270 degrees sillon) form the ultrastructural basis for the "crista," first described by light microscopy. Unique rosette structures corresponding to the "chambers" or "ovoid inclusions" of light microscopy were detected at the periphery of all protoplasmic cylinders. Polar organelles and linearly aligned flagellar insertions are conspicuous. In size and complexity, Cristispira more resembles Pillotina, Diplocalyx, Clevelandina and Hollandina (large spirochetes symbiotic in termites) than it does Treponema. Cristispira pectinis (Gross, 1910), the type species; Spirillum ostrea (Noguchi, 1921); and another, less frequent bacterial symbiont are the predominant inhabitants of the dense style matrix. The ultrastructure of the spirillum and an electron micrograph of the third bacterium are shown.

Animals↗
PubMed1975

Carotid body of Camelus dromedarius.

The carotid body of the camel is located between a mass of loose connective tissue at the point of separation of the internal carotid artery from the carotid trunk. A capsule-like connective tissue sheath sends strands in between the parenchyme of this organ and separates lobes and lobules, making it disseminated in type, as in man and in the horse. Two distinct types of cells were found in the parenchyma. Type I cells with specific electton-dense, cored vesicles, and type II cells with protoplasmic extensions. Unlike the previously reported arrangement in the carotid body of some species, the type I cells have direct contact with the basement membrane of glomi and capillaries. Synaptic contacts were seen on both cell types.

Animals↗
PubMed1999

Reticular theory versus neuron theory in the work of Camillo Golgi.

In 1873 Golgi invented a revolutionary method for microscopic research of the nervous system, based on a particular technique for staining nerve cells, which came to be known as "black reaction". Thanks to this method, he was able to provide a thorough and precise description of nerve cells in various regions of the cerebro-spinal axis, clearly distinguishing the axon from the dendrites. He drew up a new classification of cells on the basis of the structure of their nervous prolongation, and he criticized Gerlach's theory of the "protoplasmic network". Golgi claimed to observe in the gray matter an extremely dense and intricate network, composed of a web of intertwined branches of axons coming from different cell layers ("diffuse nervous network"). This structure, which emerges from the axons and is therefore essentially different from that hypothesized by Gerlach, appeared in his view to be the main organ of the nervous system, the organ that connected different cerebral areas both anatomically and functionally by means of the transmission of an electric nervous impulse. Golgi's reticular theory, along with the other reticular theories of the nervous system prevalent at the end of the nineteenth century, had in a certain sense overturned the 'atomistic-reductionist' principle that lay behind the cell theory. These theories were in fact based on a holistic model, according to which the cerebro-spinal axis was considered to be a continuous structure, and its functions the result of a collective action. At the end of the 1880's, Ramon y Cajal began to elaborate the neuron theory, using Golgi's microscopic technique. Golgi, however, did not accept this theory, and a controversy arose between the two scientists that was not put to rest even after the rivals were both awarded the Nobel Prize in 1906. If we look at the reasons for which Golgi opposed the neuron theory, we can see that they derived not so much from disagreement over the actual data observed, as from a different way of conceiving the anatomo-physiological architecture of the nervous system: Golgi appeared to support a holistic conception of the nervous system, the same that lay behind the theories of the opponents to cerebral localization, whereas Cajal and the 'neuronists' embraced an 'atomistic-reductionist' assumption, according to which the nervous system is made up of the sum of just so many neurons, each of which is an anatomical, functional, and embryological individuality, and not merely a < > in a network of nervous filaments.

History, 19th Century↗
PubMed2001

Information forgotten or overlooked: fundamental flaws in the conventional view of the living cell.

Old ideas often persist long after sound evidence dictates otherwise. I attempt to report one such case in the life sciences, by pointing out what are perceived to be fundamental flaws or questions in conventional wisdom. It is my experience that much evidence not in support of the well accepted membrane pump view of the living cell has been overlooked, forgotten or even ignored. In presenting this idea, the evolution of our knowledge from the establishment of cellular and protoplasmic theory to the emergence of solution theory is presented. The universal hypothesis based on physical chemical principles is presented, followed by the advent of the membrane-situated energy-requiring pump. The experimental demonstration of an inadequate energy supply for the first pump is discussed, followed by a review of new evidence that calls to question the use of dilute solution theory in describing adequately cellular function. Finally, roles for cellular water are suggested to explain the cellular exclusion of sodium and to serve as a barometer for the healthy state. Within the context of a metaphor, I attempt to qualitatively embrace the physical findings. It is concluded that the mobility of water molecules may be considered to change with the progression of normal tissue to a state of disease. These changes in the mobility of water molecules are "fingerprinted" by changes in the molecular motion of the solids.

Animals↗
PubMed2000

[Comparison of physiological characteristics of different ecotype plants].

Studies on the responses of photosynthesis, leaf water content and stoma resistance of 4 different ecotype plants to water stresses showed that their mechanism of drought-resistance was different. Mesic plants limited water loss from transpiration by increasing their stoma resistance, while xeric plants decreased water loss by keeping the high concentration of cell protoplasm. The latter had a higher efficiency of keeping water than the former. The leaf water content and stoma resistance was decreased from mesic to xeric plants, while the net photosynthetic rate per unit leaf was increased, indicating the difference of physiological characteristics among different ecotype plants.

Photosynthesis↗