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PubMed2025

Microbe-induced gene silencing of fungal gene confers efficient resistance against Fusarium graminearum in maize.

UNLABELLED: Small RNAs (sRNAs), the main effectors of RNA interference (or RNA silencing, RNAi), mediate cell-autonomous and non-cell-autonomous gene silencing. The discoveries of trans-kingdom RNAi and interspecies RNAi have accelerated the development of RNAi-based crop protection technologies. Recently, based on interspecies RNAi, a practical technology termed microbe-induced gene silencing (MIGS) without the need of host genetic modification is developed for crop protection against Verticillium dahliae and Fusarium oxysporum in cotton and rice plants. In this study, we utilized MIGS technology to protect maize against Fusarium graminearum, which is responsible for maize stalk rot. An RNAi-engineered Trichoderma harzianum strain, Th-FgPmt2i, was exploited to generate double-stranded RNAs (dsRNAs) to trigger the silencing of the FgPTM2 gene. Our data verify that sRNAs generated from Th-FgPmt2i can silence the FgPMT2 gene via translational inhibition in F. graminearum. We further demonstrated that Th-FgPmt2i has a stronger capacity than does the T. harzianum chassis for protection of maize against F. graminearum. Coupled with our studies on crop protection against V. dahliae and F. oxysporum, our findings reveal that MIGS can be exploited to protect various crops against distinct fungal pathogens and has extensive applicability. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s42994-025-00212-9.

Fusarium graminearum↗
PubMed1978

Mutagenicity of fume particles from metal arc welding on stainless steel in the Salmonella/microsome test.

Mutagenic activity of fume particles produced by metal arc welding on stainless steel (ss) is demonstrated by using the Salmonella/microsome mutagenicity test described by Ames et al., with strain TA100 (base-pair substitution) and TA98 (frame-shift reversion). Results of a representative but limited selection of processes and materials show that mutagenic activity is a function of process and process parameters. Welding on stainless steel produces particles that are mutagenic, whereas welding on mild steel (ms) produces particles that are not. Manual metal arc (MMA) welding on stainless steel produces particles of higher mutagenic activity than does metal inert gas (MIG) welding, and fume particles produced by MIG welding under short-arc transfer. Further studies of welding fumes (both particles and gases) must be performed to determine process parameters of significance for the mutagenic activity.

Gases↗
PubMed1975

Delayed hypersensitivity in the mouse induced by hapten-carrier complexes.

Delayed hypersensitivity (DH) in the mouse was studied with complexes of dinitrophenyl (DHP) as hapten and bovine serum albumin (BSA), mouse immunoglobulin (MIg) and polyvinylpyrrolidone (PVP) as carrier. Priming with BSA induced strong DH against this carrier, but DN of decreasing strength against complexes with increasing DNP:carrier ratio. Priming with DNP-BSA complexes never resulted in a DH against BSA or DNP 3-minusBSA. Injections of DNP 16-minusBSA and DNP 28-minusBSA induced positive DH which increased with the hapten:carrier ratio of the eliciting antigen. The complexes with an isologous carrier DNP 48-minusMIg or DNP 90-minusMIg induced positive reactions against both complexes but not against the weakly substituted DNP 11-minusMIg. The latter only primed for itself. The importance of the DNP groups as determinant in these DH reactions is stressed by the cross-reactions between DNP-BSA and DNP-MIg complexes and by the induction by DNP 16-minusPVP of positive DH against DNP 28-minusBSA. Cyclophosphamide (Cy) treatment before priming with complexes induced enhanced DH against complexes with sufficient hapten:carrier ratio. Priming with carrier under Cy treatment induced no DH against complexes. All these results indicate that carrier determinants are not involved in the DH against complexes. After priming wtih complexes with a low hapten:carrier ratio the DH is directed against new antigenic determinants (NAD) groups. After priming with complexes with high ratios DH is directed against DNP groups. With adoptive local transfer of spleen cells of primed animals and pretreatment of these cells with anti-thymocyte serum or anti-plasma cell serum and complement it was possible to demonstrate that the T cell was responsible for the DH reactions. The involvement of different determinant groups on the hapten-carrier complexes in immune reactions is discussed.

Animals↗
PubMed2026

Quantifying niche overlap and transgression in allopolyploid hybrids: Case study of Sorbus subgenus Aria.

BACKGROUND AND AIMS: Apomixis, the formation of seeds without recombination, facilitates adaptation and persistence under environmental change. By preserving hybrid genotypes over long time periods, apomixis may conserve adaptive trait combinations from parental niche margins. We tested whether apomictic entities occupy intermediate, marginal, or transgressive niche space relative to their parents and whether differentiation is associated with ploidy. METHODS: We studied polyploid Sorbus subgenus Aria in the Franconian Jura (Germany), comprising two progenitors Sorbus aria and S. collina, seven triploid entities, and a pool of genetically heterogenous individuals (single genotypes). Genetic structure was assessed using MIG-seq. Overall niche differentiation between parental taxa and hybrids was evaluated using Sørensen similarity of two-dimensional hypervolumes derived from principal component analysis (PCA) axes. Niche shifts were further analyzed using hypervolumes based on the three strongest PCA variables. Across 762 occurrences, observations ranged from 11 to 453 individuals per entity. KEY RESULTS: Environmental niche space was transgressive in three, significantly allocated towards the margins of parental niche space in one, while remaining intermediate in the other entities. Niche transgression occurred towards milder temperatures and drier conditions. Genetic analyses confirmed morphologically defined entities, although one morphotype was polyphyletic. Tetraploid S. collina significantly occupied warmer and wetter environments compared to other cytotypes. Triploids differed from S. aria along microtopographic gradients represented by the second PCA axis. CONCLUSIONS: Apomictic Sorbus entities show diverse strategies in niche occupation and can occupy environmental niche space at and beyond the limits of their parental taxa. Apomicts may conserve evolutionary adaptations at the edges of parental niche space that may otherwise be lost from, or fail to emerge in, the parental gene pool. Over long timescales these trait combinations may re-enter the parental gene pool through introgression, thereby reintroducing adaptations critical for survival under changing conditions.

Aria↗
PubMed2025

Genomic signature and evolutionary history of completely cleistogamous lineages in the non-photosynthetic orchid Gastrodia.

Despite a long-standing interest since Darwin's time, the genomic implications of obligate self-fertilization remain elusive. Complete cleistogamy-the obligate production of closed, self-pollinating flowers-represents an extreme reproductive strategy. Here, we present the genomic profiles and evolutionary history of two lineages of the mycoheterotrophic orchid Gastrodia, both of which independently acquired complete cleistogamy, based on detailed sampling and a combination of simple sequence repeat (SSR), multiplexed ISSR genotyping by sequencing (MIG-seq) and RNA-seq data. Our analysis reveals clear species delimitation, with no evidence of introgression between the completely cleistogamous species and their co-occurring allogamous sisters. Intriguingly, all analyses indicate that both the completely cleistogamous Gastrodia species and their allogamous sisters exhibit genetic profiles typical of self-pollinating plants. This pattern suggests that their ancestors, probably bearing allogamous flowers, had already evolved mechanisms to mitigate the deleterious effects of selfing, potentially facilitating the emergence of complete cleistogamy through benefits such as reproductive assurance, enhanced colonization ability and species reinforcement. Meanwhile, further analyses suggest that complete cleistogamy evolved very recently (possibly within the last 1000-2000 years) in these two Gastrodia lineages. Combined with the scant evidence of complete cleistogamy outside Gastrodia, our findings imply a limited and ephemeral role for complete cleistogamy in plant speciation.

Biological Evolution↗
PubMed2004

Genetic analysis of pathways regulated by the von Hippel-Lindau tumor suppressor in Caenorhabditis elegans.

The von Hippel-Lindau (VHL) tumor suppressor functions as a ubiquitin ligase that mediates proteolytic inactivation of hydroxylated alpha subunits of hypoxia-inducible factor (HIF). Although studies of VHL-defective renal carcinoma cells suggest the existence of other VHL tumor suppressor pathways, dysregulation of the HIF transcriptional cascade has extensive effects that make it difficult to distinguish whether, and to what extent, observed abnormalities in these cells represent effects on pathways that are distinct from HIF. Here, we report on a genetic analysis of HIF-dependent and -independent effects of VHL inactivation by studying gene expression patterns in Caenorhabditis elegans. We show tight conservation of the HIF-1/VHL-1/EGL-9 hydroxylase pathway. However, persisting differential gene expression in hif-1 versus hif-1; vhl-1 double mutant worms clearly distinguished HIF-1-independent effects of VHL-1 inactivation. Genomic clustering, predicted functional similarities, and a common pattern of dysregulation in both vhl-1 worms and a set of mutants (dpy-18, let-268, gon-1, mig-17, and unc-6), with different defects in extracellular matrix formation, suggest that dysregulation of these genes reflects a discrete HIF-1-independent function of VHL-1 that is connected with extracellular matrix function.

Animals↗
PubMed1977

Acute lymphoblastic leukemia (ALL) antigens detected with antisera to E rosette-froming and non-E rosette-forming ALL blasts.

Based on the presence or absence of erythrocyte receptors(E) a T cell marker, acute lymphocytic leukemia (ALL), can be divided into E+ALL and E-ALL. We studied cell surface antigens on blasts from 12 children with untreated ALL: eight with E-ALL and four with E+ALL. Heterologous antisera were raised against thymus cells, E+ and E-ALL blasts, appropriately absorbed and tested by immunofluorescence and a radiolabeled antibody assay with normal and leukemic lymphoid cells. By both methods, anti-thymus and anti-E+ALL sera reacted with human thymocytes. Specific binding of anti-E+ALL serum to T antigens was indicated by the fact that a single absorption with thymocytes abolished its binding to allogenic thymocytes, and the reactivity of anti-E+ALL serum with thymus, blood and bone marrow lymphocytes was similar to that of anti-thymus serum. After exhaustive absorption with blood leukocytes, anti-E+ALL and E-ALL sera were negative against normal lymphocytes and bone marrow cells from children with ALL in remission. Anti-thymus and anti-E+ALL sera reacted with blasts from patients with E+ALL, but not with E-ALL. In contrast, anti-E+ALL serum reacted with 40 to 96% of blasts from all children with E-ALL, whereas of the four patients with E+ALL, two were negative and two had the lowest percentage of immunofluorescent cells (10 to 22%). These results were confirmed with the radiolabeled antibody assay. Patients with active E-ALL had cells bearing E-ALL antigen(s) in the peripheral blood and bone marrow, but the number of immunofluorescent cells was lower in blood. Cells reactive with anti-E-ALL serum did not react with thymus cells, blood lymphocytes, remission bone marrow cells, Raji cells, PWM and PHA-induced blasts and CLL cells bearing mIg (uk). These data suggest that the antigen detected on E-ALL blasts by anti-E-ALL serum is neither a HLA-related nor a cell differentiation antigen. Thus, by using antiserum to E+ALL blasts, we have confirmed the presence of a T cell-specific antigen(s) on E+ALL cells. This antiserum did not recognize other leukemia-associated antigens common to E+ and E-ALL. We have also demonstrated an antigen(s) which is regularly expressed on E-ALL blasts and is either not detectable or is present in a lower proportion of E+ALL blasts.

Age Factors↗
PubMed1975

Antibody formation in the mouse induced by hapten-carrier complexes.

The influence of hapten, carrier and their ratio in a complex on T-cell helper stimulation and antibody formation against the dinitrophenyl (DNP) hapten was studied. Complexes of DNP with bovine serum albumin (BSA), bovine gamma-globulin (BGG), isologous mouse immunoglobulin (MIG) and polyvinylpyrrolidone (PVP) as carriers were used. Optimal antibody formation against DNP was obtained with complexes with an intermediate hapten:carrier ratio (DNP 16-minusBSA, DNP 43-minusBGG and DNP 48-MINUSMIG). DNP-PVP complexes were not active either in the primary or in the secondary response. The anti-BSA titre was independent of the number of DNP groups on the complex used for immunization. Inhibition of DNP-plaque formation by spleen cells of immunized mice shows an increase of the inhibitory capacity of the complex with the increase of the hapten-carrier ratio. DNP 16-minusPVP was the only PVP complex which was inhibitory. These results suggest that helper cells involved in the antibody formation against BSA and DNP are reactive with different parts of the complex. Priming of mice with carrier or complex after cyclophosphamide (Cy) treatment followed by a secondary injection with complex 10 days later gave strong indications that there is a greater involvement in stimulation of helper T cells by determinants of the complex (new antigenic determinants (NAD) or NAP-DNP groups) or DNP, than by true BSA determinants. This holds for both the IgM and IgG responses.

Animals↗
PubMed1975

Cell co-operation and hapten--carrier complexes.

The co-operation of spleen cells of carrier- and hapten--carrier-primed mice in antibody formation against the hapten part of complexes was studied in 550 rad whole body irradiated mice. Hapten--carrier complexes were prepared with the 2,4-dinitrophenyl group (DNP) as a hapten and heterologous bovine serum albumin (BSA) and isologous mouse immunoglobulin (MIg) as carriers. Priming of donor mice with carrier alone did not prepare for a secondary (IgG) response in the recipients of hapten--carrier. Priming of donors and challenge of recipients with the same hapten--carrier complex resulted in high IgG responses. Whereas donor and recipient immunization with complexes differing in the carrier did not give a secondary response, addition of cells of donors immunized with the carrier of the complex used for challenge, resulted in a secondary response. This was only possible when at least one of the complexes had an intermediate hapten:carrier ratio. Only an IgM or a low IgG response was obtained if both complexes had a high hapten:carrier ratio. Three determinants, namely hapten and carrier groups and new antigenic determinant (NAD), are suggested for antibody formation against hapten--protein complexes. In vivo treatment of donor cells with anti-thymocyte serum (ATS) or anti-plasma cell serum (APCS) and complement (C) suggested that: (1) T-cell epitopes are present on the carrier; (2) DNP groups are B-cell epitopes; (3) NAD and possibly DNP are T-cell epitopes; (4) synergism exists in the collaborative antibody response of B cells recongnizing DNP, T cell recognizing carrier and T cells recognizing NAD. Mitomycin treatment of donor cells was used to test whether cell division was mandatory. While the B cells were sensitive to mitomycin treatment, no effect of this drug was found on the helper activity of T cells.

Animals↗