THE SEPTAL PORES OF COPFINUS LAGOPUS IN RELATION TO NUCLEAR MIGRATION

The septal pores of homokaryotic and dikaryotic mycelia of Coprinus lagopus have the complex structure characteristic of certain Basidiomycetes. The edge of the pore is thickened and covered on either side by a dome-shaped, perforated, membranous cap. However, in heterokaryotic mycelia in which nuclear migration was believed to be taking place, in addition to the complex pores, simple pores were also observed as well as various intermediate stages interpreted as steps in the breakdown of complex to simple pores. The simple pores may facilitate nuclear migration.     

Somatic nuclear division in the sporidia of Ustilago violacea. III. Ultrastructural observations.

The paper provides detailed ultrastructural observations on nuclear division in the smut fungus Ustilago violacea and is based on previous light-microscopic work outlining the division in living and stained cells. The division as in many other Basidiomycetes is not intranuclear, but occurs within a partially disrupted membrane. The division takes place after migration of most of the nucleus into the bud cell, after limited breakdown of the nuclear membrane, and after the formation of a spindle between two spindle-pole bodies (SPB). The remaining part of the nucleus containing the nucleolus is left behind in the parent cell and degenerates there. The SPB, as in other Basidiomycetes, is a dome-shaped relatively structureless body, quite distinct from the flat plaques of many Ascomycetes and the elaborat centrioles of Phycomycetes. The SPB divides shortly before migration into the daughter cell and invariably is located at the apex of the migrating nucleus. Nuclear division is completed when the two masses of chromatin clustered about each of the SPB's are separated as the spindle elongates. One daughter neculeus reforms in the bud and the other is reformed in the mother cell. Cells fixed and stained by conventional light-microscopic methods were examined in the light of the electron-microscopic observations to determine whether these procedures induce artefacts. Aceto-orcein and Giemsa when used cold were found to produce relatively artefact-free preparations. However, previous results in which the cells were warmed gently in these stains are now seen to contain artefacts in the form of contracted chromatinic granules often arranged in chains. These artefacts may provide useful information but clearly they must be interpreted cautiously until the nature of the changes induced by heating are known.     

Nucleotide Composition of Nuclear and Mitochondrial Deoxyribonucleic Acid of Fungi

The buoyant density of nuclear and mitochondrial deoxyribonucleic acid (DNA) from 14 species of fungi was determined by CsCl density gradient equilibrium centrifugation. The buoyant density of both types of DNA was the same for all three Mucorales analyzed. The buoyant density of mitochondrial DNA was significantly lower than that of the nuclear DNA for nine species of Ascomycetes and two species of Basidiomycetes. No simple correlation could be obtained from the comparison of the two types of DNA. Mitochondrial DNA represented a very small proportion of total DNA. Heat-denatured mitochondrial DNA renatured more readily than nuclear DNA.     

Cancer cell migration in 3D tissue: Negotiating space by proteolysis and nuclear deformability

Efficient tumor cell invasion into the surrounding desmoplastic stroma is a hallmark of cancer progression and involves the navigation through available small tissue spaces existent within the dense stromal network. Such navigation includes the reciprocal adaptation of the moving tumor cell, including the nucleus as largest and stiffest organelle, to pre-existent or de-novo generated extracellular matrix (ECM) gaps, pores and trails within stromal compartments. Within the context of migration, we briefly summarize physiological and tumor-related changes in ECM geometries as well as tissue proteolysis. We then focus on mechanisms that ensure the successful translocation of a nucleus through a confining pore by cytoskeleton-mediated coupling, as well as regulators of cell and nuclear deformability such as chromatin organization and nuclear lamina expression. In summary, understanding dynamic nuclear mechanics during migration in response to confined space will add to a better conceptual appreciation of cancer invasion and progression.     

Biotransformations of aryl alkyl sulfides by whole cells of white-rot Basidiomycetes

White-rot Basidiomycetes promoted the oxidation of aromatic pro-chiral sulfides into sulfoxides with good enantioselectivity, conversion and a small production of sulfones. The reactions were carried out using whole cells of Irpex lacteus, Pycnoporus sanguineus, Trichaptum byssogenum, Trametes rigida, Trametes versicolor and Trametes villosa. The enantioselectivity for all the aryl alkyl sulfoxides was in favor of (S)-enantiomers. Oxidation of (phenylpropyl)sulfide produced (S)-(phenylpropyl)sulfoxide with high enantiomeric excess (e.e. ≥99%) by all the Basidiomycetes employed. Basidiomycetes isolated from Brazilian biomes were used as biocatalysts in the oxidation reaction.     

Ultrastructure of the dikaryotic form ofCyathus bulleri brodie

The fine structure of the dikaryotic form ofCyathus bulleri Brodie was generally found to be similar to that of other hyphal forms of the Basidiomycetes. The nuclear walls were doubled, porous and in some cases connected to the endoplasmic reticulum. The presence of typical as well as filamentous and U-shaped mitochondria was confirmed. Other cellular structures and organelles, among them vacuoles, vesicular and myelinoid-like bodies, often associated with the cell membranes, glycogen and ribosomes were also observed in the cytoplasm. The presence of the dolipore/parenthesome apparatus and clamp connections typical of the Basidiomycetes was established.     

Free-radical scavenging activity of submerged mycelium extracts from higher basidiomycetes mushrooms

Twenty-four Basidiomycetes strains were evaluated to determine their free-radical scavenging capacity in submerged cultivation. The scavenging capacity of the extracts varied from 1 to 85% depending on the mushroom species, solvent used, and concentration. A calculation of EC(50) of extracts from several wood-rotting Basidiomycetes showed high scavenging abilities at low effective concentration.     

Paternal and maternal effects on propagule size in Anthoxanthum odoratum

Summary Propagules (caryopsis plus glumes) from a diallel cross among eight genotypes of Anthoxanthum odoratum were weighed to asses the relative contribution of nuclear, reciprocal, and environmental effects to propagule size. Maternal reciprocal effects were large whereas zygotic nuclear effects were small, although consitently present. There were no interactions between maternal reciprocal and nuclear effects. Environmental effects were large, including environmentally induced maternal effects and within individual variance. These results suggest that response to selection for seed size as a result of sib-competition will be weak, and that seed size differences are relatively unimportant for the maintenance of sexual reproduction in natural populations.     

FINE STRUCTURE OF MYCOTA. 7. OBSERVATIONS ON SEPTA OF ASCOMYCETES AND BASIDIOMYCETES

Moore , R. T., and J. H. Mc Alear . (Cornell U., Ithaca, N. Y.) Fine structure of mycota. 7. Observations on septa of Ascomycetes and Basidiomycetes. Amer. Jour. Bot. 49(1): 86–94. Illus. 1962.—Electron microscopy of 13 carpomycete species (5 Ascomycetes, 5 Basidiomycetes, and 3 Deuteromycetes) presents evidence that suggests there is an Ascomycete- and a Basidiomycete-type septum. The observed Ascomycete septa taper slightly or not at all toward a simple, clear-channel, central pore, while the observed Basidiomycete septa flare sharply and broadly at the center to produce what is termed a dolipore septum. On each side of this septum is a double membrane structure that is crescent-shaped in section. This is given the name parenthesome. These dolipore-parenthesome septa were found to be characteristic of basidiocarpic, dikaryotic, hyphae. Interpretative drawings of both types of septa are presented. From these and the micrographs, it is not difficult to see how materials, including nuclei, could pass through the Ascomycete-type septum, but it would appear that the modifications of the Basidiomycete-type septum while maintaining cytoplasmic continuity would prohibit nuclear migration in dikaryotic hyphae. It is postulated that as the plant and animal phylogenetic lines have developed actual diploidism, the terminal group of the fungi may have achieved functional diploidism. Of the 3 species of Deuteromycetes examined, 2, Aspergillus variecolor and Stilbum zacalloxanthum, have typical Ascomycete-type septa; the third, QM 7739, has Basidiomycete-type septa. This fungus is a species of Sclerotium, but the present confusion and lack of definitive information regarding the taxonomy, genetics, and perfect stage of this genus prohibit the enlarging at present on the possible significance of this observation.     

Hyperdiversity of ectomycorrhizal fungus assemblages on oak seedlings in mixed forests in the southern Appalachian Mountains

Diversity of ectotrophic mycobionts on outplanted seedlings of two oak species (Quercus rubra and Quercus prinus) was estimated at two sites in mature mixed forests in the southern Appalachian Mountains by sequencing nuclear 5.8S rRNA genes and the flanking internal transcribed spacer regions I and II (ITS). The seedlings captured a high diversity of mycorrhizal ITS-types and late-stage fungi were well represented. Total richness was 75 types, with 42 types having a frequency of only one. The first and second order jackknife estimates were 116 and 143 types, respectively. Among Basidiomycetes, tomentelloid/thelephoroid, russuloid, and cortinarioid groups were the richest. The ascomycete Cenococcum geophilum was ubiquitously present. Dominant fungi included a putative Tuber sp. (Ascomycetes), and Basidiomycetes including a putative Craterellus sp., and Laccaria cf. laccata. Diversity was lower at a drier high elevation oak forest site compared to a low elevation mesic cove--hardwood forest site. Fungal specificity for red oak vs. white oak seedlings was unresolved. The high degree of rarity in this system imposes limitations on the power of community analyses at finer scales. The high mycobiont diversity highlights the potential for seedlings to acquire carbon from mycelial networks and confirms the utility of using outplanted seedlings to estimate ectomycorrhizal diversity.     

Genetics of leukocyte telomere length and its role in atherosclerosis

Malnutrition is a serious public health problem that affects approximately one third of all children. Developing countries have the highest incidence of malnourished children, and approximately 60% of deaths that occur in children under five are directly related to malnutrition and associated diseases. The relationship between malnutrition and genetic damage has been widely studied in humans and animal models. The micronucleus (MN) assay is useful in detecting chromosome damage induced by several factors. The aim of this study was to evaluate the effects of infection and malnutrition on the frequency of MN in erythrocytes from the peripheral blood of well-nourished, uninfected (WN) and well-nourished, infected (WNI) children, and moderately malnourished (UNM) and severely malnourished (UNS) children, both with infection, using a flow cytometric analysis technique. The percentage of reticulocytes (RETs) was significantly higher (1.5-fold) in WNI children than well-nourished controls. In addition, the UNS group had a 2.2-fold increase in the percentage of RETs compared to the WNI group. The frequency of micronucleated reticulocytes (MN-RETs) was 2.5 times greater, in WNI group compared to the WN group. These frequencies were significantly higher (1.7- and 2.1-fold) in UNM and UNS, respectively, compared to the WNI group. The results suggest that infection and malnutrition induce DNA damage in children.     

Morphogenesis in Schizophyllum commune. I. Effects of White Light

Reproductive differentiation in the basidiomycete Schizophyllum commune Fr. is initiated by plasmogamy and reciprocal nuclear migration and is terminated by the production of basidiospores. The work reported here has analyzed several factors that affect 2 sequential steps in reproductive differentiation: A) the formation of aggregated masses of cells, and B) the subsequent differentiation of fruiting bodies. The 2 steps are both photosensitive: A) light accelerates the formation of aggregated masses of cells; B) a short exposure of light induces nonaggregated dikaryotic cells to form mature fruiting bodies in the dark.     

CTHRC1 promotes growth,migration and invasion of trophoblasts via reciprocal Wnt/β-catenin regulation

Preeclampsia (PE) is a pregnancy complication that is characterized by high blood pressure and is associated with high maternal and fetal morbidities. At a mechanistic level, PE is characterized by reduced invasion ability of trophoblasts. Collagen triple helix repeat containing-1 (CTHRC1) is a well-known tumor-promoting factor in several malignant tumors, but its role in trophoblasts remains unknown. In this study, we characterized the expression of CTHRC1 in placenta tissue samples from PE pregnancies and from normal pregnancies. We used the trophoblasts cell lines HTR-8/SVneo and JEG-3 to investigate the role of CTHRC1 in cell migration, invasion and proliferation. Western blot, PCR and TOP/FOP luciferase activity assays were used to investigate the molecular mechanisms underlying these cell behaviors. Placenta tissue samples obtained from pregnant women with PE expressed lower levels of CTHRC1 than those of placenta tissues from women with normal pregnancies. Down-regulation of CTHRC1 impaired cell proliferation, migration and invasion of trophoblasts, while CTHRC1 overexpression promoted nuclear translocation of β-catenin, a result that was further confirmed by TOP/FOP luciferase activity assay. Our findings suggest that CTHRC1 promotes migration and invasion of trophoblasts via reciprocal Wnt/β-catenin signaling pathway. Down-regulation of CTHRC1 may be a potential mechanism underpinning the development of preeclampsia.     

Genomic scans reveal multiple mito‐nuclear incompatibilities in population crosses of the copepod Tigriopus californicus

The evolution of intrinsic postzygotic isolation can be explained by the accumulation of Dobzhansky‐Muller incompatibilities (DMI). Asymmetries in the levels of hybrid inviability and hybrid sterility are commonly observed between reciprocal crosses, a pattern that can result from the involvement of uniparentally inherited factors. The mitochondrial genome is one such factor that appears to participate in DMI in some crosses but the frequency of its involvement versus biparentally inherited factors is unclear. Here we assess the relative importance of incompatibilities between nuclear factors (nuclear‐nuclear) versus those between mitochondrial and nuclear factors (mito‐nuclear) in a species that lacks sex chromosomes. We used a Pool‐seq approach to survey three crosses among genetically divergent populations of the copepod, Tigriopus californicus, for regions of the genome that are affected by hybrid inviability. Results from reciprocal crosses suggest that mito‐nuclear incompatibilities are more common than nuclear‐nuclear incompatibilities overall. These results suggest that in the presence of very high levels of nucleotide divergence between mtDNA haplotypes, mito‐nuclear incompatibilities can be important for the evolution of intrinsic postzygotic isolation. This is particularly interesting considering this species lacks sex chromosomes, which have been shown to harbor a particularly high number of nuclear‐nuclear DMI in several other species.     

Immunocytochemical localization of cyclin/proliferating cell nuclear antigen (PCNA) in fertilized eggs of mice.

Immunolocalization of cyclin/PCNA (proliferating cell nuclear antigen) was performed with monoclonal antibody using immunogold methods on ultrathin cryosections of fertilized mouse eggs. Immunolabeling in pronuclei was checked 20, 22, 24 and 26 h after HCG injection. A relation between onset of pronuclei migration (early S-phase) and appearance of colloidal particle clusters was found. Afterwards, (mid S-phase) the increase of labelling and the localization of cyclin/PCNA were found throughout the pronuclei, except in the nucleolar bodies. Lower labelling appeared at the time of close reciprocal pronuclei contact (late S-phase). It is concluded that bulk and distribution of cyclin/PCNA in pronuclei is closely related to the progression of first interphase after fertilization.     

Viability of cytochrome c genotypes depends on cytoplasmic backgrounds in Tigriopus californicus

Because of their extensive functional interaction, mitochondrial DNA (mtDNA) and nuclear genes may evolve to form coadapted complexes within reproductively isolated populations. As a consequence of coadaptation, the fitness of particular nuclear alleles may depend on mtDNA genotype. Among populations of the copepod Tigriopus californicus, there are high levels of amino acid substitutions in both the mtDNA genes encoding subunits of cytochrome c oxidase (COX) and the nuclear gene encoding cytochrome c (CYC), the substrate for COX. Because of the functional interaction between enzyme and substrate proteins, we hypothesized that the fitness of CYC genotypes would depend on mtDNA genotype. To test this hypothesis, segregation ratios for CYC and a second nuclear marker (histone H1) unrelated to mitochondrial function were scored in F2 progeny of several reciprocal interpopulation crosses. Genotypic ratios at the CYC locus (but not the H1 locus) differed between reciprocal crosses and differed from expected Mendelian ratios, suggesting that CYC genotypic fitnesses were strongly influenced by cytoplasmic (including mtDNA) background. However, in most cases the nature of the deviations from Mendelian ratios and differences between reciprocal crosses are not consistent with simple coevolution between CYC and mtDNA background. In a cross in which both newly hatched larvae and adults were sampled, only the adult sample showed deviations from Mendelian ratios, indicating that genotypic viabilities differed. In two of six crosses, large genotypic ratio differences for CYC were observed between the sexes. These results suggest that significant variation in nuclear-mtDNA coadaptation may exist between T. californicus populations and that the relative viability of specific cytonuclear allelic combinations is somehow affected by sex.     

Trichosporonoides nigrescens sp. nov., a new xerophilic yeast-like fungus

A new yeast-like fungus isolated from jam on two occasions is described as Trichosporonoides nigrescens. It is a true xerophile, able to grow at water activities at least as low as 0.75. For this reason, its carbon assimilation pattern was examined using both dilute (standard) and concentrated carbon sources: six to nine compounds not assimilated at the standard concentrations of 0.5% (0.001 to 0.1 mol/kg) were assimilated at 1.5 to 2.0 mol/kg. Cell wall and septal ultrastructure, DNA base ratios, and the nuclear cycle were examined to determine the generic and higher taxonomic affinities of this microorganism. All properties were consistent with its assignment to Trichosporonoides Haskins et Spencer. However, while ultrastructure indicated an affinity with the Basidiomycetes, the mitotic nuclear cycle and the xerophilic nature of this fungus suggested an Ascomycete affinity. The GC content (57%) is consistent with assignment to either. No teleomorphic state was found.     

Reciprocal effects in anther cultures of wheat hybrids

This study was conducted to determine the reciprocal effects for anther culture response in wheat (Triticum aestivum L.) using a set of 4 × 4 full diallel crosses. Both reciprocal and nuclear genetic effects were highly significant for anther culture response and useful for selection and breeding purposes. General combining ability (GCA) effects were predominant for all investigated anther culture traits. Also, significant differences for specific combining ability (SCA) effects were detected between reciprocal crosses. Although significant reciprocal differences for responding anther, callus number and green plant regeneration were recorded in some reciprocal crosses, there were no significant reciprocal differences for albino plant regeneration. The use of one parent as male or female could lead to change at the production of green plants from the F₁ hybrids and screening of inbred lines for response to anther culture, without reciprocal effects, could decrease the utilization of breeding material.     

Mutations Affecting Embryonic F-Actin Reorganization also Affect Separation of Nuclei from their Sisters and from the Cortex in Drosophila Cleavage Embryos

We showed in Drosophila that nuclear migration was reduced all through cleavage stages in embryos with any one of the maternal-effect mutations, gs(1)N441 and gs(1)N26 , in which F-actin reorganization in cleavage embryos is disordered. Moreover, we determined nuclear positions in embryos at cycle 1 and 2 in the wild type and two mutants, gs(1)N441 and gs(1)N26 , in order to test if the nuclear migration is regulated within a nuclear cycle. At cycle 1, there was no difference in nuclear position among the strains that we observed. At cycle 2 the two sister nuclei had already migrated posteriorly in the wild type. However, migration was not detectable at cycle 2 in the mutants. Besides, the two sister nuclei were less-separated from each other, and orientation of the two nuclei with regard to the anteroposterior axis was random, different from the wild type. These results support the hypothesis that F-actin is involved in the regulation to separate cleavage nuclei from each other and from the egg cortex. This regulation is apparently required for posteriorward nuclear migration, and for synchronous nuclear arrival in the whole egg cortex.