Molecular Cytology Research Articles

Immunocytochemistry of plant defense mechanisms induced upon microbial attack.

During the past few years, cyto- and immunocytochemical techniques have been developed and widely used for locating and identifying various molecules in plant cell compartments. The last decade has witnessed tremendous improvements in molecular cytology, thus allowing an accurate in situ detection of various components thought to play important biological functions in the plant metabolism. The use of immunocytochemistry to investigate resistance mechanisms of plants upon pathogen attack has provided key information on the defense strategy that plants elaborate during a host-pathogen interaction. Of the various proteins induced in response to infection, chitinases and beta-1,3-glucanases have been the focus of particular attention due to their believed antimicrobial activity through the hydrolysis of the main fungal wall components, chitin and beta-1,3-glucans. Attention has also been paid to beta-fructosidase, the enzyme that hydrolyzes sucrose into glucose and fructoside. The marked accumulation of this enzyme upon pathogen infection has led to the consideration that infection may greatly influence the metabolic activity of colonized tissues by creating alterations of source-sink relationships. Another facet of the plant's defense strategy that has been the focus of considerable interest is related to the accumulation of structural compounds, such as hydroxyproline-rich glycoproteins and callose, to reinforce the wall architecture, thus decreasing vulnerability to microbial enzymes. A number of alternatives designed to improve plant protection towards pathogen invasion have been suggested. Among these, the production of transgenic plants expressing constitutively a foreign resistance gene and the pretreatment of plants with elicitors of defense reactions have been the subject of intensive studies at the molecular, biochemical, and cytological levels. Results of such studies clearly demonstrate the important contribution that cyto- and immunocytochemical approaches can make to our knowledge of how plants defend themselves and how plant disease resistance can be directly enhanced. These approaches will undoubtedly be active areas for future research in the development of biological control alternatives in which the mode of action of the product used is of key importance.

Editorial comments: C‐ERBB‐2 in Retrospect: Is it time for molecular cytology?

Editorial comments: C‐ERBB‐2 in Retrospect: Is it time for molecular cytology?

Lung tumor cells: a multivariate approach to cell classification using two-dimensional protein pattern.

High resolution two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) is a powerful research tool for the analytical separation of cellular proteins. The qualitative and quantitative pattern of polypeptides synthesized by a cell represents its phenotype and thus defines characteristics such as the morphology and the biological behavior of the cell. By analyzing and comparing the protein patterns of different cells it is possible to recognize the cell type and also to identify the most typical features of these cells. In applied pathology it is often difficult to identify the tissue of origin and the stage or grade of a neoplasia by cellular morphology analyzed by classical or immunostaining procedures. The protein pattern itself is the most characteristic feature of a cell and should therefore contribute to the identification of the cell type. For this reason we separated protein fractions originating from different lung tumor cell lines using 2-D PAGE and we compared the resulting patterns on a multivariate statistical level using correspondence analysis (CA) and ascendant hierarchical clustering (AHC). The results indicate that (i) protein patterns are highly typical for cells and that (ii) the comparison of the protein patterns of a set of interesting cell types allows the identification of potentially new marker proteins. 2-D PAGE is thus a unique and powerful tool for molecular cytology or histopathology, unveiling the protein expression level of tissues or cells.

Productivity and cytogenetic characteristics of guayule. Screening of plants from the mapimi region

AbstractGuayule plants were screened in the region of Mapimi (Durango, Mexico) to evaluate physicochemical parameters for selection of increased productivity. The objective was to characterize rubber, and resin content, stem diameter, rubber molecular weight and cytology of these plants to identify and select high productivity sites. Samples were collected from nine locations within the Mapimi Region. Inflorescences containing young floral buds of the same plants were selected to determine ploidy level. Cytogenetic results showed the presence of di‐, tri‐ and tetraploids. Samples for rubber and resin analysis were cut from the branches. Genetic variation in molecular weight and molecular weight distributions for rubber was measured. Significant differences were found in resin content and stem diameter between the sampling sites, but differences were not significant for the rubber content between sites. A productivity parameter was defined and used to identify two locations where guayule genotypes exhibited the best characteristics for commercialization. This information may increase the industrial development and understanding of the polymerization bioprocess.

An in vivo study on the synchronizing effect of hydroxyurea

The effect of hydroxyurea (HU; 0.5 mg/g body wt) on L 1210 ascites tumor cells has been studied using various cell kinetic methods. In contrast to the general assumption that HU blocks cells at the G 1/S boundary [J. Brachet (1985) Molecular Cytology, Vol. I, p. 266, Academic Press, New York], the present results show that the cells are not held at G 1/S but enter S at about the normal rate and are accumulated in early S phase due to a dose-dependent inhibiting effect of HU on DNA synthesis. Partial synchronization of the cells demonstrated by a distinct mitotic peak 10 h after HU application is not due to a G 1/S block of the cells and their subsequent synchronous passage through the cycle after release from the block but is due to rather complex mechanisms of action of HU: a differential cytocidal effect and an effect on the passage of the cells through the cycle, both depending on the position of the cells throughout the cycle. HU kills S-phase cells, mainly cells in early S phase; i.e., a great portion of the cells “accumulated” in early S phase is killed by the drug, while G 1-phase cells are almost not affected by the lethal effect of HU. These G 1-phase cells pass through the cycle more rapidly after cessation of the HU effect. The same is true for the surviving cells accumulated in early S phase, while part of the cells in the remaining S phase are delayed in their passage through the cycle. This causes partial synchronization, since a great portion of all cells that survive HU treatment reach mitosis at the same time.

Genomic and Phylogenetic Relationships among Rye and Perennial Species in the Triticeae1

Genomic and phylogenetic relationships among rye (Secale cereale L.) and eight perennial species representing the genera Pseudoroegneria, Thinopyrum, and Elymus were analyzed by in situ hybridization with two repeated DNA sequence probes from rye. The 120‐base pair (bp) sequence was observed to be present in all the perennial species, but only Thinopyrum elongatum showed an in situ hybridization pattern similar to that of rye. In both species, the 120‐bp sequence was distributed throughout the entire length of all seven pairs of chromosomes. The other species showed weak labeling or few sites of hybridization with the 120‐bp sequence. The 480‐bp sequence, which is specific to S. cereale, was detected in eight pairs of chromosomes of Thinopyrum intermedium and in one pair of chromosomes of Elymus trachycaulus. The labeled chromosomes in the hexaploid T. intermedium may have consisted of chromosomes from the ✕ genome, whose origin is unknown and is distinctly different from the two related genomes present in this species. This is the first report on the occurrence of the 480‐bp sequence (in the ✕ genome of T. intermedium) outside of the genus Secale and may indicate either a phylogenetic relationship or an independent amplification event. The results of the 120‐bp sequence confirm the widespread occurrence of this sequence in the Triticeae tribe. Both sequences provide valuable markers for molecular cytology (e.g., 120‐bp sequence for E genome and 480‐bp sequence for ✕ genome) for use in controlled introgression of useful traits from species containing these genomes into wheat.

The Use ofXenopusOocytes for the Study of Ion Channel

Recently, in addition to the "traditional" research on meiotic reinitiation and fertilization mechanisms, the oocytes of the African frog Xenopus laevis have been exploited for the study of numerous aspects of ion channel function and regulation, such as the properties of several endogenous voltage-dependent channels and the involvement of second messengers in mediation of neurotransmitter-evoked membrane responses. In addition, injection of these cells with exogenous messenger RNA results in production and functional expression of foreign membranal proteins, including various voltage- and neurotransmitter-operated ion channels originating from brain, heart, and other excitable tissues. This method provides unique opportunities for the study of the structure, function, and regulation of these channels. A multidisciplinary approach is required, involving molecular biology, electrophysiology, biochemistry, pharmacology, and cytology.

Book reviews

Journal Article Book reviews Get access Molecular Cytology, Vol. 1: The Cell Cycle J. Brachet ( 1985) Academic Press, London £59.50 P. Hollands P. Hollands Search for other works by this author on: Oxford Academic PubMed Google Scholar Human Reproduction, Volume 1, Issue 4, 1 June 1986, Page 281, https://doi.org/10.1093/oxfordjournals.humrep.a136403 Published: 01 June 1986

Bacterial anatomy in retrospect and prospect.

Progress in bacterial anatomy over a period of about 15 years is reviewed. In particular, attention is paid to developments in which the Department of Electron Microscopy and Molecular Cytology was involved. Past and present problems in bacterial anatomy as well as approaches to their solution are discussed.

Cells and Molecules. (Book Reviews: Handbook of Molecular Cytology)

Cells and Molecules. (Book Reviews: Handbook of Molecular Cytology)

General introduction to cytoplasm.

A mere glance at figures 1 and 2 is enough to demonstrate, in a schematic way, how different our present understanding of cell structure is from that of E. B. Wilson, some 40 years ago: while the essential constituents of the cell nucleus were already known, the cytoplasm had an alveolar (or fibrillar) structure, where no cell organelles (besides the centrosomes) could be seen. This over-cautious representation of cytoplasmic structure was due to the fear of fixation and staining artifacts, as a consequence of the work of J. Loeb and his followers on the properties of colloids. Nowadays, we think in terms of macromolecules rather than miscellae, and we have good reasons to think that microscopy can give a fairly accurate picture of cell structure. When I was a student, our professors did not believe in Golgi bodies, in nuclear membranes, in spindle and aster fibres; even mitochondria were considered as possible artifacts. Everything has changed, within a few decades, thanks to the introduction of new techniques: cytochemistry gave us information about the chemical nature of the various cell inclusions which could be stained by the classical methods; electron microscopy clearly demonstrated that mitochondria, Golgi bodies, centrosomes, aster and spindle fibres, etc., really exist. Biochemistry, under the influence of men like D. Keilin, R. Peters, A. Claude, C. de Duve, etc. succeeded in isolating many cell constituents and in analysing them. Thanks to the cooperation of cytochemical, electron microscopical and biochemical methods, a clearer and more dynamic picture of cellular organization and functioning is now emerging. In the present Discussion, biochemists (Sir Rudolph Peters, C. de Duve), biophysicists (Sir John Randall) and biologists will join forces in order to make progress in the field of ‘molecular cytology’, the study of the cell of today and tomorrow.