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PubMed2006

The ubiquitin system and morphogenesis of fungal pathogens.

Distinct fungal species exhibit different cellular morphologies, such as yeast and filamentous (hyphal and pseudohyphal) forms, that are reflected in the macroscopic colony morphology. Dimorphic and multimorphic fungi can switch between these different morphologies, enabling the utilization of different food supplies in the case of saprophytes, and contributing to pathogenesis in the case of parasites. Cellular morphogenesis is often regulated by signal transduction pathways, and is intimately linked to the cell cycle machinery. Here we describe the role of ubiquitin-mediated degradation of cell cycle regulators and transcription factors involved in fungal morphogenesis.

Cell Cycle↗
PubMed1990

Fine localization of the acetylcholinesterase activity in somatic and germ cells during the morphogenesis of chick ovarian cortex.

The ultracytochemical localization of the enzyme acetylcholinesterase (AChE) was studied in the germinal epithelium and cortex during chick ovarian morphogenesis at the 7, 12.5, 14 and 19 day of incubation. The results evidenced at day 7 the presence of the enzyme in some somatic cells, both "dark" and "light" and in some gonocytes. The reaction appears also in some tracts between these types of cells. At day 12.5 the reaction is present in some somatic cells only towards the deepest zone of the cortex, in many oogonia and oocytes and in some tracts between germ and somatic cells. At day 14 and day 19 the various cell categories of the cortex are negative for the reaction. The significance of the presence of the enzyme is discussed in relation to an embryonic cholinergic system active during morphogenesis. Regarding the presence of the enzyme in germ cells, the positivity in endoplasmic reticulum cisternae associated to mitochondria may suggest an implication of the enzymatic activity in the proliferation and transformation of these organelles.

Acetylcholinesterase↗
PubMed1990

Contribution to knowledge of the morphogenesis of the nasal apparatus of the fallow deer (Dama dama L.).

As in the red deer, in the fallow deer embryo we found a number of ancestral structures reminiscent of relationships in other mammals, such as paraseptal cartilages, a septum nasi with trabecular widening, a lamina transversalis ant., a cart. ectochoanalis, a capsule wall with a roof and a lateral wall formed of a clearly distinguishable cart. parietotectalis and cart. paranasalis, an ethmoturbinale I projecting a long way rostrally and additionally, in the fallow deer, cart. paraseptales posteriores. I regard the relationship of the cart. alaris inf. to the parietotectal cartilage (or "marginoturbinale") as relatively "primitive"; this may mean that the term "atrioturbinale" is also justified in mammals and that the relevant structure is homologous with the one known by the same name in birds. The specializations found during study of the morphogenesis of the nasal apparatus in the red deer (Slabý 1990b) are accentuated in the fallow deer. The chief ones are the specific rostral processes of the anlage of the nasal septum, which are a significant part of reinforcement of the nostril, the marked widening of the nasal capsule in a lateral direction (so that even the paranasal cartilages have a largely horizontal course), the striking ventrolateral bulge in the nasal capsule at the beginning of the olfactory region and the final resultant decrease in the height (i. e. flattening) of the capsule. This leads to reduction of the frontoturbinalia and their corresponding recesses, which - where they are developed - are oriented more horizontally. The structure of ethmoturbinale I, together with its insertion, is also simplified. As in the corresponding red deer embryo, the paranasal cartilage zone in the anterior part of the olfactory region is strikingly thickened; the frontoturbinalia do not, however, originate (in our stage) by the formation of cavities in the cartilage, but develop as simple processes. A crista semicircularis and foramen epiphaniale and also, as distinct from the red deer embryo, cart. paraseptales posteriores, are clearly discernible. In conclusion, it can therefore be claimed that the morphogenesis of specialized cervid features is accentuated in Dama more than in Cervus and that relationships in the fallow deer represent a further step in specialization, or - if we are speaking of the development of radiations - specialization here has progressed further.

Animals↗
PubMed1990

Morphogenesis of the nasal apparatus of the red deer (Cervus elaphus L.).

Three stages of morphogenesis of the nasal apparatus of the red deer (Cervus elaphus L.) were studied. Many ancestral traits reminiscent of relationships in other mammals and even in reptiles were found, including a cart, ectochoanalis, paraseptal cartilages, the septum nasi and its ventral trabecular enlargement, a lamina transversalis ant., clear separation of the cart, parietotectalis and cart, paranasalis from each other and a crista semicircularis. A maxilloturbinale, was present, but not a nasoturbinale. The main specific features were a completely rostrally localized, peculiar cartilaginous structure in the preseptal space, for which there is as yet no morphological explanation, and pronounced bulging of the cartilaginous wall of the nasal capsule in a ventrolateral direction, level with the rostral region of the olfactory labyrinth (caudally to the aboral end of the maxilloturbinale). In the early stages of morphogenesis, it was found that the ethmoturbinalia might be formed by fusion of the edges of the anlagen of the paranasal cartilage and the lamina orbitonasalis. The structure of the olfactory labyrinth was reminiscent of its organization in the sheep embryo; the recessus frontalis was completed by a series of frontoturbinal recesses and frontoturbinalia, which are poorly developed in the red deer, however. The floor of the caudal part of the nasal capsule was very little developed and there was no cart, paraseptalis post.

Animals↗
PubMedDate not supplied

[Interactions between the extracellular matrix and the cell surface determine tooth morphogenesis and the cellular differentiation of the dental mesenchyme].

A series of reciprocal interactions between epithelial and mesenchymal tissues control the morphogenesis and cell differentiation in the developing tooth. The molecular mechanisms operating in these interactions are, however, unknown at present. Structural components of the extracellular matrix (ECM) affect cellular behavior in the embryo and appear to be involved also in these regulatory processes. The ECM molecules exert their effects on cells through binding to specific matrix receptors on the cell surface. This review article summarizes our findings on the distribution patterns during tooth development of the ECM glycoproteins, fibronectin and tenascin, and of the cell surface proteoglycan, syndecan, which functions as a receptor for interstitial matrix. Based on the observed changes in these distribution patterns and on experimental evidence, roles for these molecules in epithelial-mesenchymal interactions during tooth development are suggested. Fibronectin and tenascin are enriched in the dental basement membrane at the time of odontoblast differentiation. These matrix glycoproteins may be involved in the cell-matrix interaction which controls differentiation of the dental mesenchymal cells into odontoblasts. Tenascin and syndecan are accumulated in the dental mesenchyme during bud stage of development. We have shown in tissue recombination experiments that the presumptive dental epithelium induces the expression of tenascin and syndecan in mesenchyme. We suggest that these molecules are involved in cell-matrix interactions, which regulate mesenchymal cell condensation during the earliest stages of tooth morphogenesis.

Basement Membrane↗
PubMed1989

Studies on the effect of monoamine antagonists on the morphogenesis of the newt.

The effects of three monoamine antagonists, p-chlorophenylalanine, diethyldithiocarbamate and propranolol on the morphogenesis of newt embryos were studied. Antagonists were administered during late blastula through neurula stages. In a concentration of 1 mM, all three arrested gastrulation and caused disintegration of the embryos. Lower concentrations (0.1-0.5 mM) retarded morphogenetic movements in the gastrulation and caused malformations especially in the anterior parts of the embryos; pigmentation was delayed by 1 or 2 days. In addition, p-CIPhe inhibited yolk granule degradation in the notochord and DEDTC caused notochordal hypertrophy. The results show that interference with synthesis or action of catecholamines and serotonin affects morphogenesis. With the methods used it is not possible to discover exactly how monoamines regulate the morphogenetic events because of the unspecific side effects of the antagonists and the feedback interactions between the monoamines.

Animals↗
PubMed1979

Tooth morphogenesis: the role of the innervation during induction and pattern formation.

The hypothesis is discussed that the innervation of the early mandibular and maxillary processes influences the initiation and patterning of tooth germs. Silver staining of embryonic mouse tissue supports the notion that the innervation is present before tooth buds appear. Data from other experimental studies is discussed in support of this hypothesis. The importance of the early events of tooth morphogenesis in initiating and patterning the dentition is discussed in the context of tooth morphogenesis as a whole. The processes involved in odontogenesis are categorized as Phase I: Initiating events; Phase II: Histogenetic events; and Phase III: Cytodifferentiative events. The complications of the interrelationship of these three seemingly discrete segments of tooth development are discussed in the context of inductive tissue interaction.

Ameloblasts↗
PubMed1986

Isolation of genes active during hormone-induced morphogenesis in Drosophila imaginal discs.

Mass-isolated Drosophila imaginal discs cultured in vitro undergo morphogenesis (evagination) in response to the insect steroid hormone 20-hydroxyecdysone. In vitro translation of mRNA isolated from evaginating discs shows accumulation of at least five new mRNA transcripts that are present only in membrane-bound polysomal RNA and presumably encode imaginal disc membrane or secreted proteins. Using a modified differential hybridization screen employing a competition step, six different hormone-inducible membrane protein gene sequences were isolated. These genes constitute a new set of 20-hydroxyecdysone responsive loci that may encode gene products specifically required for imaginal disc morphogenesis.

Animals↗
PubMedDate not supplied

[Morphogenesis and growth potentials of organ cultures of the respiratory tract anlage of mice susceptible and resistant to pulmonary blastomogenesis].

The morphogenesis and growth potencies have been studied in the long-term organ cultures of different parts of the respiratory tract early rudiment in the mouse strains susceptible (A) and resistant (C57BL) against lung blastomogenesis. Similarities and peculiarities have been shown for the lung rudiment cells developing in vitro and in vivo. The linear differences have been established in morphogenesis and growth potencies of the proximal and distal parts of the respiratory tract rudiment. Possible importance of phenotypic differences in realization of the genetically determined sensitivity of the mouse-lung tissue to spontaneous and induced blastomogenesis is discussed.

Animals↗
PubMedDate not supplied

[Structural mechanisms for the realization of the secretory activity of human endocrine organs in prenatal morphogenesis].

A study was made of the secretory active cells and intraorganic blood channel of the hypophysis, thyroid, thymus, ovaries and testes and human embryos and fetuses of 4-5 week -9 mos intrauterine development. The development of the hematocellular barriers in the human endocrine organs during the period of intrauterine development was studied from the view-point of the expression of their secretory activity. The time course of the transmission of endocrine information in the endocrine glands during prenatal morphogenesis determined by the phases of the development of transport communications of the microcirculatory system was studied. The system of contact means of the transmission of the secretory material was the first to function in the endocrine glands in the prenatal period of morphogenesis. The structural-functional formation and development of the microcirculatory system was a morphological base for the expression of the long- and short-distant means of the transmission of the secretory material to target cells and organs.

Cell Communication↗
PubMedDate not supplied

Immunohistochemical study of crystallin synthesis during morphogenesis of the crystalline lens in mice.

Using indirect immunofluorescence, the sequence of the synthesis of various classes of crystallins during normal morphogenesis of the crystalline lens in mice was shown: The alpha- begin to be synthesized first, then the gamma-, and finally the beta-crystallins. Using mice with hereditary anophthalmia (genotype ey-1/ey-1 ey-2/ey-2) permitted it to be established that the synthesis of alpha-crystallins occurs even when there is no morphogenesis of the crystalline lens. In mice of this genotype, the lens placode, which is reduced as compared to the norm, is resorbed as a rule, and does not develop into the crystalline lens vesicle. Separate cells containing alpha-crystallins were found in cranial epithelium on serial cross sections of the eye area of 13-day-old mutant embryos. Consequently, in ey-1/ey-1 ey-2/ey-2 embryos, alpha-crystallin synthesis takes place even in cells of the resorbed lens placode after brief inducing influence of the optic vesicle. As opposed to alpha-crystallins, synthesis of gamma- and beta-crystallins is detected only when lens fibers have formed. This is characteristic for embryos of ey-1/ey-1 ey-2/ey-2 genotype, as well as for mouse embryos homozygous for the fi gene. Data of the present work indicate that the inducing influence of the optic vesicle is necessary for activation of the genes controlling alpha-crystallin synthesis, while the influence of the retinal rudiment is necessary for derepression of the genes for gamma- and beta-crystallin synthesis.

Animals↗
PubMed1979

Concanavalin A binding to amphibian embryo and effect on morphogenesis.

The effect of Concanavalin A (Con A) on morphogenesis in Pleurodeles waltlii has been studied. Embryos were incubated with various concentrations of the lectin for a period of 6 days. Three stages of development were examined, late blastula, young gastrula and late gastrula. In the presence of the lectin at a concentration of 200, 150 or 100 micrograms/ml morphogenic movements were delayed, altered and finally blocked. At lower concentrations, 50 or 25 microgram/ml, there was a slight delay in gastrulation, but in some cases development was normal. These findings indicate that Con A exerted an inhibitory effect on amphibian morphogenesis and there is evidence that the lectin effect was concentration dependent. The effects of Con A were specific since they were totally inhibited by alpha-methyl-D-mannopyranoside (0.05 M). The viability of the 24 h lectin-treated embryos was demonstrated by washing experiments. Labelled Con A binding to the embryos was investigated before and after discarding the vitelline membrane. The results suggest a direct interaction between Con A and the cell surface and this was confirmed by using fluorescein isothiocyanate Con A.

Animals↗
PubMed1985

N-acetyl-D-glucosamine-induced morphogenesis in Candida albicans.

N-acetylglucosamine is a morphogenic effector in the human pathogenic yeast Candida albicans. Depending on temperature, N-acetylglucosamine induces yeast-mycelial conversion or chlamydospore formation. N-acetylglucosamine is also a carbon source for growth in the yeast form. Germ-tube formation, i.e. the intermediary of yeast-mycelial conversion, is induced at temperatures in excess of 33 degrees C; at lower temperatures the yeast or the pseudomycelial form of the organism predominates. 2-Deoxyglucose, at concentrations which do not affect yeast growth, is a potent inhibitor of N-acetylglucosamine-induced germ-tube formation. N-acetylglucosamine suffices as both the inducer and the carbon sources for morphogenesis and both transcription and translation are required for the yeast to mycelial transition. The metabolism of N-acetylglucosamine is essentially the same for yeast phase cells (28 degrees C) and germ-tube forming cells (37 degrees C): enzymes for N-acetylglucosamine uptake and catabolism are equally well induced by gene expression at 28 degrees C and 37 degrees C. During germ-tube formation, the chitin content and the activity of the regulatory enzyme chitin synthase increase. Germ-tube formation in C. albicans can also be induced gratuitously by a number of N-acetylhexosamine derivatives (N-acetylglucosamine covalently linked to agarose, N-acetylmannosamine, hyaluronic acid, colloidal chitin, and mucin). These compounds are not taken up by the yeast cells and do not support growth which suggests that germ-tube formation is triggered by a cell-surface receptor mechanism. It is proposed that, after binding to the receptor, N-acetylglucosamine produces an intracellular message which primes the cell for morphogenesis. This message would ultimately be responsible for the choice of the mode of growth, spherical versus apical, that is characteristic of yeast or mycelial form.

Acetylglucosamine↗
PubMed1985

Improved development of rat embryos in culture during the period of craniofacial morphogenesis.

To study the mammalian craniofacial development, the culture conditions of rat whole embryo during the period of major craniofacial morphogenesis were examined. The improved rotating apparatus which is gassed continuously was used. Rat embryos explanted at 11.5 days (plug day 0) developed in vitro for up to 72 hr, that is, throughout the period of major craniofacial morphogenesis, and cultured embryos showed normal facial formation. The medium was equilibrated with a gas mixture of 95% 02, 5% CO2. The 100% rat serum improved the protein content of embryos cultured for 48 hr compared with the medium consisting of 50% rat serum and 50% Tyrode solution, although somite number was not altered. Furthermore, 100% rat serum containing 2 mg/ml glucose was the best medium for supporting growth of embryos when it was measured by protein content. Thus, the best culture medium was pure rat serum containing 50 units/ml penicillin, 50 micrograms/ml streptomycin, and 2 mg/ml glucose. Protein content, body weight, craniofacial formation, and somite number of embryos cultured for 48 hr with continuous gassing were much better than those cultured with noncontinuous gassing.

Animals↗
PubMed1974

[Morphogenesis of reconstructed enucleated Acetabularia cells].

Survival and morphogenesis of the enucleated fragments of Acetabularia has been studied after their reconstruction from the cell membrane and the endoplasm. Membranes and endoplasms of different species as well as of the same species but from plants in different functional states and with different regenerative abilities were combined. It was shown that inability of plants for growth and morphogenesis was due to the membrane state. When reconstructing anuclear fragments from membranes and endoplasms of different species or the same species but from plants in different functional states, a phenomenon of membrane-endoplasm incompatibility was found.

Acetabularia↗
PubMed1979

In vitro studies on the morphogenesis and differentiation of the mesoderm subjacent to the apical ectodermal ridge of the embryonic chick limb-bud.

It has been suggested that one of the major functions of the apical ectodermal ridge (AER) of the embryonic chick limb-bud is to maintain mesenchymal cells directly subjacent to it (i.e. cells extending 0.4-- 0.5 mm from the AER) in a labile, undifferentiated condition. We have attempted to directly test this hypothesis by subjecting the undiffertiated subridge mesoderm of stage-25 embryonic chick wing-buds to organ culture in the presence and absence of the AER and the ectoderm that normally surrounds the mesoderm dorsally and ventrally. During the period of culture, control explants comprised of the subridge mesoderm capped by the AER and surrounded by the dorsal/ventral ectoderm undergo progressive morphogenesis characterized by polarized proximal to distal outgrowth and changes in the contour of the developing explant, and ultimately form a structure grossly resembling a normal distal wing-bud tip. In contrast, explants from which the AER and dorsal/ventral ectoderm have been removed (minus ectoderm explants) or from which just the AER has been removed (minus AER explants) form compact, rounded masses exhibiting no signs of morphogenesis. During the polarized proximal to distal outgrowth control explants undergo during the first 3 days of culture, as cells of the explant become located greater than 0.4--0.5 mm from the AER, they concomitantly undergo a sequence of changes indicative of their differentiation into cartilage. However, those cells which remain 0.4--0.5 mm from the AER during this period retain the characteristics of non-specialized mesenchymal cells. In marked contrast to control explants, virtually all of the cells of minus ectoderm explants initiate chondrogenic differentiation during the first day of culture. Cells comprising the central core of minus AER explants also initiate chondrogenic differentiation during the first day of culture, but in contrast to minus ecotderm explants, non-chondrogenic tissue types form along the periphery of the explants subjacent to the dorsal/ventral ectoderm. These results indicate that the AER maintains cells directly subjacent to it in a labile, undifferentiated condition, and that when mesenchymal cells are freed from the AER's influence either artificially or as a result of normal polarized outgrowth, they are freed to commence cytodifferentiation. The results further suggest that the dorsal/ventral ectoderm may have an influence on the differentiation of the mesenchymal cells directly subjacent to it, once the cells have been removed from the influence of the AER.

Animals↗
PubMed1979

An analysis of the aggregation and morphogenesis of area opaca endoderm cells from the primitive-streak chick embryo.

The aggregative behaviour and subsequent morphogenesis of extra-embryonic endoderm cells from primitive-streak chick embryos have been investigated. A relatively pure population of area opaca endoderm cells was obtained by differential dissociation, which involves partial separation of epiblast and endoderm cell clumps by sieving through Nitex mesh. For aggregation studies cells were cultured in rotating flasks in Leibovitz (L-15) medium, in saline or in saline supplemented with glucose (1 mg/ml). Aggregation was monitored using the Coulter Counter. In these three media aggregation is rapid; by 10 min an average of 61% of the population had aggregated, to reach a plateau at 30 min when an average percent adhesion value of 83% was obtained. The aggregates in L-15 medium were large and compact. After several days in culture, they cavitated and formed smooth hollow vesicles with thin walls composed of one or a few cell layers. Aggregates formed in PCS were smaller and looser in appearance; the addition of glucose resulted in a certain degree of compaction. Some morphogenesis occurred under these conditions with the aggregates developing numerous irregular cavities. These experiments suggest that some of the factors that affect cell adhesion in early embryonic cells can be studied in vitro. The results also indicate that the ability to cavitate is an intrinsic property of the endoderm cells of the area opaca since this occurs in the absence of epiblast or mesoderm.

Animals↗