A REGULATORY SYSTEM CONTROLLING INHIBITION IN THE SEXUAL CYCLE OF NEUROSPORA

1969 ◽  
Vol 11 (3) ◽  
pp. 689-705 ◽  
Author(s):  
H. Branch Howe Jr. ◽  
V. Prakash
Keyword(s):  
Mating Type ◽  
Inhibitory Activity ◽  
Regulatory System ◽  
Inhibitory Effect ◽  
Sexual Cycle ◽  
Opposite Mating Type ◽  
Partial Inhibition ◽  
Total Inhibition ◽  
Steady Rate ◽  
Rate Of Movement

A cross made by adding conidia to protoperithecia on a mycelium of opposite mating type inhibits a subsequent cross on the same mycelium, or on an adjacent mycelium connected either by hyphae or medium. The inhibitory activity reaches a steady rate of movement through the area of the second cross from the area of the first cross and brings about either total or partial inhibition of the second cross, depending upon certain controllable variables; translocation of the activity occurs primarily through the hyphae but to a lesser degree through the medium as well. Total inhibition is not a result of modification of the medium by the first cross, such as depletion of nutrients or change in pH. An uncrossed mycelium which received activity from a crossed mycelium becomes inhibited either irreversibly or, to a certain extent, reversibly, depending upon the degree of activity received; in either event, transmission of this passive activity may occur from this mycelium to an outgrowing mycelium on fresh medium. The experiments reported here were done primarily with N. tetrasperma, in which the inhibitory effect was first found, but the effect has also been observed in N. crassa.

Induction of plasma inhibitors of interleukin 1 and TNF-alpha activity by endotoxin administration to normal humans

1990 ◽  
Vol 259 (5) ◽  
pp. R993-R997 ◽  
Author(s):  
G. A. Spinas ◽  
D. Bloesch ◽  
M. T. Kaufmann ◽  
U. Keller ◽  
J. M. Dayer
Keyword(s):  
Inhibitory Activity ◽  
Interleukin 1 ◽  
Regulatory System ◽  
Inhibitory Effect ◽  
Tnf Alpha ◽  
Necrosis Factor Alpha ◽  
Endotoxin Administration ◽  
Inhibitory Capacity ◽  
Pge2 Release ◽  
Bolus Intravenous Injection

Several naturally occurring inhibitors of interleukin 1 (IL-1) and tumor necrosis factor-alpha (TNF-alpha) have been demonstrated both in serum and urine of febrile patients. These factors are considered to be part of a regulatory system counteracting potential deleterious effects of the cytokines. We have assayed plasma samples of volunteers who received a bolus intravenous injection of either 4 ng/kg body wt of Escherichia coli endotoxin (n = 6) or 0.9% saline (n = 4) for the presence of IL-1 and TNF-alpha inhibitory activity. Plasma obtained 3 h after endotoxin injection inhibited IL-1-induced PGE2 release from fibroblasts by 57% (P less than 0.001 vs. baseline and saline controls, respectively). Maximal IL-1 inhibitory capacity coincided with fever and tended to disappear with declining body temperature. Normal plasma was found to inhibit TNF-alpha-induced PGE2 release by 20-35%. This inhibitory effect increased to 50-60% in plasma obtained during endotoxinemia. Maximal TNF-alpha inhibitory capacity became detectable when circulating TNF-alpha levels peaked at 120 min after the injection of endotoxin. Our data demonstrate that both IL-1 and TNF-alpha inhibitory activity can be induced experimentally by intravenous endotoxin administration to humans and that their appearance coincides with fever and circulating TNF-alpha levels.

scholarly journals Uniparental sexual reproduction following cell-cell fusion of opposite mating-type partners

2020 ◽  
Author(s):  
Vikas Yadav ◽  
Sheng Sun ◽  
Joseph Heitman
Keyword(s):  
Mating Type ◽  
Genetic Material ◽  
Nuclear Genome ◽  
Sexual Cycle ◽  
Uniparental Inheritance ◽  
Opposite Mating Type ◽  
Fluorescent Reporter ◽  
Unisexual Reproduction ◽  
F1 Progeny ◽  
Opposite Sex

AbstractSome animal species require an opposite-sex partner for their sexual development but discard the partner’s genome before gamete formation, generating hemi-clonal progeny in a process called hybridogenesis. In this study, we discovered hybridogenesis-like reproduction in a basidiomycete fungus, Cryptococcus neoformans. C. neoformans has two mating types, MATa and MATα, which fuse to produce a dikaryotic zygote that completes a sexual cycle producing recombinant meiotic progeny. Here, we discovered exclusive uniparental inheritance of nuclear genetic material in a fraction of the F1 progeny produced during bisexual reproduction of two opposite mating-type partners. By analyzing strains expressing fluorescent reporter proteins, we observed that dikaryotic hyphae were produced, but only one parental nuclei was found in the terminal basidium where sporulation occurs. Whole-genome sequencing revealed the nuclear genome of the progeny was identical with one or the other parental genome, whereas the mitochondrial genome was always inherited from the MATa parent. Uniparental sporulation was also observed in natural isolate crosses occurring in concert with biparental sporulation. The meiotic recombinase Dmc1 was found to be critical for uniparental reproduction. These findings reveal an unusual mode of eukaryotic microbial unisexual reproduction that shares features with hybridogenesis in animals.

Improved media for testing the mating reaction and genetic complementation of Ustilago hordei

1992 ◽  
Vol 70 (4) ◽  
pp. 788-793 ◽  
Author(s):  
Alfredo D. Martinez-Espinoza ◽  
Karla J. Dugan ◽  
Michael E. Bjarko ◽  
John E. Sherwood
Keyword(s):  
Mating Type ◽  
Activated Charcoal ◽  
Rapid Identification ◽  
Sexual Cycle ◽  
Mating Test ◽  
Opposite Mating Type ◽  
Mating Reaction ◽  
Ustilago Hordei ◽  
Key Words Barley ◽  
The Stability

The sexual cycle of Ustilago hordei, which results in the formation of teliospores, requires growth on its barley host for completion. However, the early steps of mating, including conjugation and the formation of dikaryotic mycelium, can occur on artificial media. The addition of activated charcoal to a variety of media enhanced the stability and intensity of the mating reaction as measured by mycelium formation. The incubation time at which the strongest mating reaction occurred was also reduced. The dikaryotic nature of the mycelia that resulted from mating on charcoal-containing media was confirmed by fluorescence microscopy. Complementation assays using minimal medium containing activated charcoal demonstrated allelism of mutations in auxotrophic sporidial strains of opposite mating type. The ease and reliability of this mating test allow for rapid identification of the mating type of unknown isolates and progeny of crosses, as well as providing a dependable procedure for performing complementation tests. Key words: barley, covered smut, Hordeum vulgare, mating type.

scholarly journals Inhibitory Effects of Secondary Metabolites from the Lichen Stereocaulon evolutum on Protein Tyrosine Phosphatase 1B

Planta Medica ◽  
2021 ◽  
Author(s):  
Birgit Waltenberger ◽  
Françoise Lohézic-Le Dévéhat ◽  
Thi Huyen Vu ◽  
Olivier Delalande ◽  
Claudia Lalli ◽  
...  
Keyword(s):  
Protein Tyrosine Phosphatase ◽  
Inhibitory Activity ◽  
Tyrosine Phosphatase ◽  
Inhibitory Effect ◽  
Positive Control ◽  
Protein Tyrosine Phosphatase 1B ◽  
Protein Tyrosine ◽  
Ic50 Values ◽  
A Cell

AbstractProtein tyrosine phosphatase 1B plays a significant role in type 2 diabetes mellitus and other diseases and is therefore considered a new drug target. Within this study, an acetone extract from the lichen Stereocaulon evolutum was identified to possess strong protein tyrosine phosphatase 1B inhibition in a cell-free assay (IC50 of 11.8 µg/mL). Fractionation of this bioactive extract led to the isolation of seven known molecules belonging to the depsidones and the related diphenylethers and one new natural product, i.e., 3-butyl-3,7-dihydroxy-5-methoxy-1(3H)-isobenzofurane. The isolated compounds were evaluated for their inhibition of protein tyrosine phosphatase 1B. Two depsidones, lobaric acid and norlobaric acid, and the diphenylether anhydrosakisacaulon A potently inhibited protein tyrosine phosphatase 1B with IC50 values of 12.9, 15.1, and 16.1 µM, respectively, which is in the range of the protein tyrosine phosphatase 1B inhibitory activity of the positive control ursolic acid (IC50 of 14.4 µM). Molecular simulations performed on the eight compounds showed that i) a contact between the molecule and the four main regions of the protein is required for inhibitory activity, ii) the relative rigidity of the depsidones lobaric acid and norlobaric acid and the reactivity related to hydrogen bond donors or acceptors, which interact with protein tyrosine phosphatase 1B key amino acids, are involved in the bioactivity on protein tyrosine phosphatase 1B, iii) the cycle opening observed for diphenylethers decreased the inhibition, except for anhydrosakisacaulon A where its double bond on C-8 offsets this loss of activity, iv) the function present at C-8 is a determinant for the inhibitory effect on protein tyrosine phosphatase 1B, and v) the more hydrogen bonds with Arg221 there are, the more anchorage is favored.

scholarly journals THE SEARCH FOR MATING-TYPE-LIMITED GENES IN THE HOMOTHALLIC ALGA CHLAMYDOMONAS MONOICA

Genetics ◽  
1986 ◽  
Vol 113 (3) ◽  
pp. 601-619
Author(s):  
Karen P VanWinkle-Swift ◽  
Jang-Hee Hahn
Keyword(s):  
Mating Type ◽  
Resistance Mutation ◽  
Mendelian Inheritance ◽  
Sexual Cycle ◽  
Uniparental Inheritance ◽  
Cell Type ◽  
Erythromycin Resistance ◽  
Type Locus ◽  
Heterothallic Species ◽  
Chlamydomonas Monoica

ABSTRACT The non-Mendelian erythromycin resistance mutation ery-u1 shows bidirectional uniparental inheritance in crosses between homothallic ery-u1 and ery-u1  + strains of Chlamydomonas monoica. This inheritance pattern supports a general model for homothallism invoking intrastrain differentiation into opposite compatible mating types and, further, suggests that non-Mendelian inheritance is under mating-type (mt) control in C. monoica as in heterothallic species. However, the identification of genes expressed or required by one gametic cell type, but not the other, is essential to verify the existence of a regulatory mating-type locus in C. monoica and to understand its role in cell differentiation and sexual development. By screening for a shift from bidirectional to unidirectional transmission of the non-Mendelian ery-u1 marker, a mutant with an apparent mating-type-limited sexual cycle defect was obtained. The responsible mutation, mtl-1, causes a 1000-fold reduction in zygospore germination in populations homozygous for the mutant allele and, approximately, a 50% reduction in germination for heterozygous (mtl-1/mtl-1  +) zygospores. By next screening for strains unable to yield any viable zygospores in a cross to mtl-1, a second putative mating-type-limited mutant, mtl-2, was obtained. The mtl-2 strain, although self-sterile, mates efficiently with mtl-2  + strains and shows a unidirectional uniparental pattern of inheritance for the ery-u1 cytoplasmic marker, similar to that observed for crosses involving mtl-1. Genetic analysis indicates that mtl-1 and mtl-2 define unique unlinked Mendelian loci and that the sexual cycle defects of reduced germination (mtl-1) or self-sterility (mtl-2) cosegregate with the effect on ery-u1 cytoplasmic gene transmission. By analogy to C. reinhardtii, the mtl-1 and mtl-2 phenotypes can be explained if the expression of these gene loci is limited to the mt  + gametic cell type, or if the wild-type alleles at these loci are required for the normal formation and/or functioning of mt  + gametes only.

ESCAPE FROM MATING-TYPE INCOMPATIBILITY IN BISEXUAL (A + a) NEUROSPORA HETEROKARYONS

1975 ◽  
Vol 17 (3) ◽  
pp. 441-449 ◽  
Author(s):  
A. M. DeLange ◽  
A. J. F. Griffiths
Keyword(s):  
Mating Type ◽  
Loss Of Function ◽  
Wild Type ◽  
Opposite Mating Type ◽  
Type Locus ◽  
Heterokaryon Incompatibility ◽  
Recessive Mutant ◽  
Type Rate ◽  
Wild Type Rate ◽  
Incompatibility Locus

In Neurospora crassa, strains of opposite mating type generally do not form stable heterokaryons because the mating type locus acts as a heterokaryon incompatibility locus. However, when one A and one a strain, having complementing auxotrophic mutants, are placed together on minimal medium, growth may occur, although the growth is generally slow. In this study, escape from such slow growth to that at a wild type or near-wild type rate was observed. The escaped cultures are stable heterokaryons, mostly having lost the mating type allele function from one component nucleus, so that the nuclear types are heterokaryon compatible. Either A or a mating type can be lost. This loss of function has been attributed to deletion since only one nuclear type could be recovered in all heterokaryons except one, but deletion spanning adjacent loci has been directly demonstrated in a minority of cases. Alternatively when one component strain is tol and the other tol+ (tol being a recessive mutant suppressing the heterokaryon incompatibility associated with mating type), escape may occur by the deletion or mutation of tol+, also resulting in heterokaryon compatibility. An induction mechanism for escape is speculated upon.

Phagocytic specificity during sexual development in Dictyostelium discoideum

1986 ◽  
Vol 32 (2) ◽  
pp. 79-82 ◽  
Author(s):  
Keith E. Lewis ◽  
Danton H. O'Day
Keyword(s):  
Dictyostelium Discoideum ◽  
Concanavalin A ◽  
Sexual Development ◽  
Wheat Germ ◽  
Giant Cells ◽  
Inhibitory Effect ◽  
Sexual Cycle ◽  
Type I ◽  
Further Development ◽  
Type Receptor

During the sexual cycle of Dictyostelium discoideum, zygote giant cells develop and serve as foci for further development by chemoattracting and cannibalizing hundreds of local amoebae. Previous work has shown that the phagocytic process bears similarities to and differences from asexual endocytosis. In the present study, sexual phagocytosis in D. discoideum was found to be species and developmental stage specific. It was inhibited selectively by glucose and concanavalin A. Although a partial, inhibitory effect of mannose on phagocytosis was not statistically significant, alpha-methylmannosamine, like alpha-methyl-glucose, significantly restored the phagocytic competence of giant cells treated with concanavalin A. Other sugars (N-acetyl glucosamine, N-acetylgalactosamine, and galactose) and lectins (wheat germ agglutinin, Ulex europus type I, and Ricinis communis agglutinin type I) had no significant effect on sexual phagocytosis. Together these data indicate that a glucose-type receptor is involved in selective uptake of D. discoideum amoebae by giant cells.

Growth-Inhibiting Properties of Xylem Exudate From Vitis vinifera

1995 ◽  
Vol 22 (1) ◽  
pp. 7 ◽  
Author(s):  
JA Campbell ◽  
BR Loveys ◽  
VWK Lee ◽  
S Strother
Keyword(s):  
Vitis Vinifera ◽  
Inhibitory Activity ◽  
Lemna Minor ◽  
Growth Inhibitor ◽  
Inhibitory Effect ◽  
Vitis Vinifera L ◽  
Inhibitory Effects ◽  
Inhibitor Activity ◽  
Xylem Exudate ◽  
Growth Inhibiting

An inhibitory effect on the growth of Lemna minor L. cultures has been demonstrated in xylem exudate from Vitis vinifera L. var. Waltham Cross bled from canes cut near the time of budburst. Most inhibitory activity was detected up to the time of maximal daily exudation, which corresponded closely with budburst. After this time the inhibitory activity rapidly disappeared. A similar pattern occurred in each of the 3 years of the study, 1988-1990. Using ultrafiltration, it was shown that most of the growth inhibitor activity of the crude exudate was located in the 0.5-10 kDa fraction. This fraction exhibited a seasonal variation in its bioactivity similar to that ofthe crude exudate samples. The 0.5-10 kDa fraction was found to contain abscisic acid but not in a sufficient quantity to account for the inhibitory effects. When chromatographically separated fractions corresponding to oligosaccharides were pooled, biological activity equivalent to that of the crude exudate was retained, which provides evidence that the inhibitor is possibly an oligosaccharide.

scholarly journals Development of mouthwash with Rosmarinus officinalis extract

2014 ◽  
Vol 50 (4) ◽  
pp. 851-858 ◽  
Author(s):  
Isabela Moreira Baumgratz de Paula ◽  
Flávia Costa Moraes ◽  
Orlando Vieira de Souza ◽  
Célia Hitomi Yamamoto
Keyword(s):  
Sodium Fluoride ◽  
Inhibitory Activity ◽  
Raw Materials ◽  
Ethanol Extract ◽  
Inhibitory Effect ◽  
Rosmarinus Officinalis ◽  
Hexane Fraction ◽  
Diffusion Method ◽  
Oral Infections

Rosmarinus officinalis, which belongs to the Lamiaceaefamily, is a species of medicinal flora with therapeutic properties. In order to exploit the benefits of these properties, a mouthwash formulation was developed, with careful selection of raw materials to meet pharmacotechnical requirements. Extracts of the plant were incorporated into a mouthwash, which was shown to have inhibitory action in vitro against the micro-organisms commonly found in periodontics. Controls for assessing the quality of the drugs were carried out, quantifying phenols and flavonoids as chemical markers. Mouthwash solutions were formulated containing 0.1, 5 and 10% ethanol extract of R. officinalis; and 0.05, 5 and 10% of the hexane fraction of R. officinalis. In order to evaluate synergism, ethanol extract and hexane fraction were also added to formulations containing 0.05% sodium fluoride and 0.12% chlorhexidine digluconate. These formulations were assessed for inhibitory effect against the specific microorganisms involved in the process of bacterial plaque formation, S. mutans(ATCC25175) and C. albicans(ATCC 10231), frequently found in cases of oral infections. The agar diffusion method was used to evaluate the inhibitory activity of extracts and formulations. All mouthwash solutions displayed inhibitory activity having higher sensitivity to S. mutansfor the 5% ethanol extract+0.05% sodium fluoride, and greater sensitivity to C. albicansfor the 10% hexane fraction. Results were characterized by the appearance of a growth inhibition halo, justifying the utilization and association of extracts of R. officinalis.

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