Basal Disc Research Articles

Hidden diversity in Antarctica: Molecular and morphological evidence of two different species within one of the most conspicuous ascidian species.

The Southern Ocean is one of the most isolated marine ecosystems, characterized by high levels of endemism, diversity, and biomass. Ascidians are among the dominant groups in Antarctic benthic assemblages; thus, recording the evolutionary patterns of this group is crucial to improve our current understanding of the assembly of this polar ocean. We studied the genetic variation within Cnemidocarpa verrucosa sensu lato, one of the most widely distributed abundant and studied ascidian species in Antarctica. Using a mitochondrial and a nuclear gene (COI and 18S), the phylogeography of fifteen populations distributed along the West Antarctic Peninsula and Burdwood Bank/MPA Namuncurá (South American shelf) was characterized, where the distribution of the genetic distance suggested the existence of, at least, two species within nominal C. verrucosa. When reevaluating morphological traits to distinguish between genetically defined species, the presence of a basal disk in one of the genotypes could be a diagnostic morphological trait to differentiate the species. These results are surprising due to the large research that has been carried out with the conspicuous C. verrucosa with no differentiation between species. Furthermore, it provides important tools to distinguish species in the field and laboratory. But also, these results give new insights into patterns of differentiation between closely related species that are distributed in sympatry, where the permeability of species boundaries still needs to be well understood.

Loss of the Polyketide Synthase StlB Results in Stalk Cell Overproduction in Polysphondylium violaceum.

Major phenotypic innovations in social amoeba evolution occurred at the transition between the Polysphondylia and group 4 Dictyostelia, which comprise the model organism Dictyostelium discoideum, such as the formation of a new structure, the basal disk. Basal disk differentiation and robust stalk formation require the morphogen DIF-1, synthesized by the polyketide synthase StlB, the des-methyl-DIF-1 methyltransferase DmtA, and the chlorinase ChlA, which are conserved throughout Dictyostelia. To understand how the basal disk and other innovations evolved in group 4, we sequenced and annotated the Polysphondylium violaceum (Pvio) genome, performed cell type-specific transcriptomics to identify cell-type marker genes, and developed transformation and gene knock-out procedures for Pvio. We used the novel methods to delete the Pvio stlB gene. The Pvio stlB− mutants formed misshapen curly sorogens with thick and irregular stalks. As fruiting body formation continued, the upper stalks became more regular, but structures contained 40% less spores. The stlB− sorogens overexpressed a stalk gene and underexpressed a (pre)spore gene. Normal fruiting body formation and sporulation were restored in Pvio stlB− by including DIF-1 in the supporting agar. These data indicate that, although conserved, stlB and its product(s) acquired both a novel role in the group 4 Dictyostelia and a role opposite to that in its sister group.

Reduction in Toxicity of Nano-Ag-Polyvinyl-pyrrolidone Using Hydra Proteins and Peptides during Zebrafish Embryogenesis.

Hydra magnipapillata cells reduce the toxicity of silver nanomaterials to zebrafish (Danio rerio) embryos. In this study, we investigated whether Hydra protein (HP) and Hydra basal disc peptide (Hym176) materials reduce nano-Ag-polyvinylpyrrolidone (N-Ag-PVP) toxicity during embryogenesis of the nanosensitive organism zebrafish. Protein (HP) was extracted from Hydra, and peptide (Hym176) was extracted from the hydra basal disc, which is attractive to nanomaterials and related to the immune system. The experimental conditions were exposure to N-Ag-PVP, HP, N-Ag-PVP+HP, Hym176, or N-Ag-PVP+Hym176 during embryo development. N-Ag-PVP+HP group showed lower toxicity than N-Ag-PVP group. In addition, in the N-Ag-PVP+HP group formed aggregated nanomaterials (≥200 nm size) through electrostatic bonding. In the gene expression profile, HP group differed in gene expression profile compared the other experimental groups and it was no genetic toxicity. HP showed a tendency to reduce side effects and abnormal gene expression produced by N-Ag-PVP with no evidence of inherent toxicity. Considering the potential nanotoxicity effects of released nanomaterials on the ecosystem, the reduction of nanotoxicity observed with HP natural materials should be regarded with great interest in terms of the overall health of the ecosystem.

Extraction and biological activity of allicin from In Vitro cultured garlic (Allium sativum L.)

The shoots of garlic (Allium sativum L.) were initiated on MS (Murashige and Skoog) medium supplemented with Benzyl adenine (BA), 4mg/L which is significantly the best among other treatments (1,2,3,5mg/L); the shoots also initiated from shoot tip in the presence of combination (NAA, 3mg/L and kinetin, 1mg/L); callus was also initiated from basal disc and shoot tip in the presence of combination (NAA, 5mg/L and kinetin 0.5mg/L) and (2,4-D, 1.5mg/L and kinetin 0.5mg/L).Rfs values of extracted allicin from bulbs, shoots, and callus were 0.97, 0.94, 0.95 respectively and the amount percentages were 1.3%, 1.8%, 2.2% respectively; identification of allicin by IR spectrum showed the similarity between the groups of extracted allicin from shoots and those of extracted allicin from bulbs (Standard); identification of allicin by UV showed one band at wave length 338nm for extracted allicin from shoot and 296nm for extracted allicin from bulbs (Standard).The results also showed the difference in the biological activity of extracted allicin from callus, shoots and bulbs of garlic toward Staphyllococcus aureus and Escherichia coli.

Recognition of Mycenasect.Amparoina sect. nov. (Mycenaceae, Agaricales), including four new species and revision of the limits of sect. Sacchariferae.

Phylogenetic reconstruction revealed that Mycena stirps Amparoina, which is traditionally classified in sect. Sacchariferae, should be treated at section level. Section Amparoina is characterised by the presence or absence of cherocytes, the presence of acanthocysts and spinulose caulocystidia. Eight species referred to Mycenasect.Amparoinasect. nov. are recognised in China. Of these taxa, four new species classified in the new section are formally described: M.bicystidiatasp. nov., M.griseotinctasp. nov., M.hygrophoroidessp. nov. and M.miscanthisp. nov. The new species are characterised by the absence of both cherocytes and a basal disc, along with the presence of acanthocysts on the pileus, spinulose cheilocystidia and caulocystidia. Descriptions of the new species, accompanied by illustrations of morphological characters and comparisons with closely related taxa, are provided. A multi-locus analysis utilising the ITS + nLSU + SSU regions was carried out using maximum likelihood and Bayesian Inference. A key to the 12 species of sect. Amparoinasect. nov. and sect. Sacchariferae that are found in China is provided.

Determining the strength of GP zones in Mg alloy AXM10304, both parallel and perpendicular to the zone

Microalloyed, age-hardenable Mg alloys can exhibit an excellent balance between strength and ductility. One such alloy, AXM10304 (Mg-1.31Al-0.33Ca-0.46Mn in wt. %), possesses high extrudability with mechanical properties comparable to 6xxx-series Al alloys at considerably lower density. The mechanical properties are due to the presence of a high number density of disc-shaped GP zones parallel to the basal planes. The present work focuses on providing a mechanistic understanding of the effect of these GP zones, on both basal and prismatic <a> slip. Using crystal plasticity simulations in conjunction with analytical strength modeling, the anisotropy in shear resistance of disc-shaped GP zones is quantitatively evaluated for the first time. It is shown that the passage of dislocations parallel to the zone (basal slip) experience a lower resistance compared to the case when the shearing occurs perpendicular to the zone (prismatic slip). This is not simply a geometrical effect; in fact, the geometry of basal discs favors the strengthening of basal slip when dislocations are not required to bow around the obstacles. Rather, it is hypothesized that the GP zone coherency strain fields contribute less resistance to basal slip as compared to prismatic slip. Furthermore, the possibility of a chemical effect is only present for the prismatic. Despite the fact that the harder mode (prismatic slip) is strengthened more than the soft, it is shown that the net strengthening effects still cause a decrease in the overall anisotropy of the individual grains, which may help to explain why the ductility is good, despite the high strength.

Deletion of Htt cause alterations in cAMP signaling and spatial patterning in Dictyostelium discoideum.

In the present study, we have analyzed in detail the functions of Htt during growth and development of the protist, Dictyostelium discoideum by creating mutants (both overexpressor and knockout). The mRNA was present at all stages of growth and development. Overexpression of htt did not show any major anomaly, while deletion resulted in delayed aggregation territory formation and showed asynchronous development especially after slug stage. The slugs formed by htt - cells showed aberration in anterior-posterior boundary, showing increased prestalk region. DdHtt regulates STAT transcription factors in the tip organizer region that help maintain patterning and culmination. In chimeras with the wild-type, htt - cells preferentially localized to the tip of the slug and basal disc regions of the fruiting body showing prestalk/stalk bias, while the overexpressing cells majorly populated the prespore/spore region showing spore bias. These differences could be attributed to protein kinase A (PKA)-regulated cyclic adenosine monophosphate (cAMP) signaling.

Mycena section Sacchariferae: three new species with basal discs from China

This current study presents three novel Mycena species that grow exclusively on specific substrata in southern China, including Castanea mollissima fruits, Fagaceae leaves and Lauraceae twigs or leaves. Mycena castaneicola belongs to Mycena section Sacchariferae stirps Amparoina, because its stipe has a prominent basal disc and it has cherocytes, acanthocysts and caulocystidia covered with spinules. The two other new Mycena species belong to M. section Sacchariferae stirps Adscendens, because of their basal disc characteristics, lack of cherocytes on the pileal surface and the presence of smooth caulocystidia. Mycena hyalinostipitata is characterised by a hyaline stipe, two types of acanthocysts and fusiform caulocystidia. Mycena substylobates can be easily distinguished by its obovoid acanthocysts and irregularly shaped caulocystidia. Detailed descriptions, line drawings and a discussion of morphological characteristics are provided herein. In addition to morphological comparisons with related taxa, phylogenetic analyses of internal transcribed spacer (ITS) nrDNA sequence data were conducted. Maximum likelihood and Bayesian inference analyses of the ITS dataset confirmed the morphology-based classification.

Characterization of FlgP, an Essential Protein for Flagellar Assembly in Rhodobacter sphaeroides.

The flagellar lipoprotein FlgP has been identified in several species of bacteria, and its absence provokes different phenotypes. In this study, we show that in the alphaproteobacterium Rhodobacter sphaeroides, a ΔflgP mutant is unable to assemble the hook and the filament. In contrast, the membrane/supramembrane (MS) ring and the flagellar rod appear to be assembled. In the absence of FlgP a severe defect in the transition from rod to hook polymerization occurs. In agreement with this idea, we noticed a reduction in the amount of intracellular flagellin and the chemotactic protein CheY4, both encoded by genes dependent on σ28 This suggests that in the absence of flgP the switch to export the anti-sigma factor, FlgM, does not occur. The presence of FlgP was detected by Western blot in samples of isolated wild-type filament basal bodies, indicating that FlgP is an integral part of the flagellar structure. In this regard, we show that FlgP interacts with FlgH and FlgT, indicating that FlgP should be localized closely to the L and H rings. We propose that FlgP could affect the architecture of the L ring, which has been recently identified to be responsible for the rod-hook transition.IMPORTANCE Flagellar based motility confers a selective advantage on bacteria by allowing migration to favorable environments or in pathogenic species to reach the optimal niche for colonization. The flagellar structure has been well established in Salmonella However, other accessory components have been identified in other species. Many of these have been implied in adapting the flagellar function to enable faster rotation, or higher torque. FlgP has been proposed to be the main component of the basal disk located underlying the outer membrane in Campylobacter jejuni and Vibrio fischeri Its role is still unclear, and its absence impacts motility differently in different species. The study of these new components will bring a better understanding of the evolution of this complex organelle.

Spore release and germling development on different substrates in the carrageenophyte Sarcothalia crispata from the southwestern Atlantic coast

Sarcothalia crispata is a carrageenophytic red alga from South America. The gametophytes produce kappa/iota carrageenan and the tetrasporophytes, lambda carrageenan, each with different properties and uses. The aims of this study were to determine the most effective method for obtaining S. crispata carpospores and tetraspores from southern Argentina, to evaluate the germination process of these spores, and to assess their survival and growth on different substrates. Desiccation, osmotic shock, low temperature, and spontaneous discharge were tested in the laboratory as spore release methods. The settlement and growth of sporelings were assessed on glass, ropes, shells, and gravel. No differences were found among induction methods, obtaining a higher output of tetraspores per frond area than of carpospores. After 3 months, shells and gravel showed the highest densities of carposporelings and tetrasporelings, while the lowest were observed on ropes and glass, respectively. Carposporeling survival varied between 88% on gravel and 13% on ropes; for tetrasporelings, mean survival was 5%. Sporelings attained the largest basal discs and longest erect portions on glass, and the smallest and shortest ones on ropes, those on shells and gravel being of intermediate in size. Based on these results, it can be concluded that carpospores and tetraspores from S. crispata obtained by spontaneous discharge and inoculated on shells and gravel will result in good densities, allowing germlings to develop and grow. This is the first study on reproductive aspects of S. crispata from the southwestern Atlantic coast, presenting valuable information for reliably initiating specific spore cultures. Obtaining this specific raw material separately for the extraction of kappa/iota or lambda carrageenan would lead to a better management of the resource by the carrageenan industry.

Life history, growth, and pigment content of two morphological variants of Hypnea pseudomusciformis (Gigartinales, Rhodophyta)

Specimens previously described as Hypnea musciformis and Hypnea nigrescens in Brazil were shown to be morphological variants of a new species named Hypnea pseudomusciformis, which has been used for the production of carrageenan on the coast of Brazil. In this study, individuals of both morphological variants were collected in the field and cultivated in unialgal culture conditions. The life history of both variants was completed in 118 days. Tetrasporophytes produced tetrasporangia in 40 days. Released tetraspores germinated and 15 days later, an erect cylindrical axis developed from basal disk. At the age of 35 days, spermatangial conceptacles could be observed, and after 3 days of co-culture of male and female gametophytes, cystocarps could be observed, indicating the occurrence of fertilization. Finally, carpospores were released from cystocarps after 10 days, germinated and originated new tetrasporophytes in 15 days. When cultured, the morphological differences between the “musciformis” and “nigrescens” variants were attenuated and the life histories were the same. Furthermore, both morphological variants had different growth rates, but similar pigment content. These results corroborate that, for Brazil, specimens previously identified as H. musciformis and H. nigrescens are variants of H. pseudomusciformis, a highly plastic species.

An individual-level selection model for the apparent altruism exhibited by cellular slime moulds

In Dictyostelium discoideum, cells that become part of the stalk or basal disc display behaviour that can be interpreted as altruistic. Atzmony et al. (Curr Sci 72:142-145, 1997) had hypothesised that this behaviour could be the outcome of an adaptive strategy based on differing intrinsic quality as reflected by phenotypes that indicate differences in potential for survival and reproduction, followed by intercellular competition among amoebae of differing qualities. Low-quality amoebae would have a poor chance of succeeding in the competition to form spores; they could enhance their chances of survival by adopting a presumptive stalk strategy. Here we extend the hypothesis by making use of recent findings. Our approach is based on the view that an evolutionary explanation for the apparent altruism of stalk cells in D. discoideum must apply broadly to other cellular slime moulds (CSMs) that exhibit stalk cell death. Further, it must be capable of being modified to cover social behaviour in CSMs with an extracellular stalk, as well as in sorocarpic amoebae whose stalk cells are viable. With regard to D. discoideum, we suggest that (a) differentiation-inducing factor, thought of as a signal that inhibits amoebae from forming spores and induces them to differentiate into basal disc cells, is better viewed as a mediator of competition among post-aggregation amoebae and (b) the products of the 'recognition genes', tgrB and tgrC, allow an amoeba to assess its quality relative to that of its neighbours and move to a position within the aggregate that optimises its reproductive fitness. From this perspective, all cells behave in a manner that is 'selfish' rather than 'altruistic', albeit with different expectations of success.

Hydraulic sediment penetration and seasonal growth of petalonamean basal discs from the Vendian of Ukraine

Around the Ediacaran-Cambrian transition, about 540 million years ago, marine organisms began to dig in the sediment that has resulted in its better ventilation and further expansion of infaunal life. Few vertical infaunal burrows are known from the Precambrian and they are usually attributed to sea anemones. Here we show that the enigmatic Ediacaran petalonamean ‘sea pens’ were able to penetrate sediment for more than one centimetre depth while anchoring the body in the microbial mat. Their growth, as evidenced by numerous well-preserved basal discs from the late Ediacaran Lomoziv Member of the Mohyliv Formation in Podolia, Ukraine, was under control of rhythmic sedimentation events and periodic microbial mat development. Size frequency distribution in classes of both the final disc size and growth retention stages show that their size increase was stepwise. Each discrete stage corresponds to deposition of a thin sediment layer and development of the microbial mat at its top. Podolia was located near the South Pole in the Ediacaran (Vendian) and such rhythmic sedimentation was probably connected with the local climate seasonality.

Antibacterial Electrospun Poly(vinyl alcohol)/Enzymatic Synthesized Poly(catechol) Nanofibrous Midlayer Membrane for Ultrafiltration.

Two different nanofibrous antibacterial membranes containing enzymatically synthesized poly(catechol) (PC) or silver nitrate (AgNO3, positive control) blended with poly(vinyl alcohol) (PVA) and electrospun onto a poly(vinylidene fluoride) (PVDF) basal disc to generate thin-film composite midlayers were produced for water ultrafiltration applications. The developed membranes were thoroughly characterized in terms of morphology, chemical composition, and general mechanical and thermal features, antimicrobial activity, and ultrafiltration capabilities. The electrospun blends were recognized as homogeneous. Data revealed relevant conformational changes in the PVA side groups, attributed to hydrogen bonding, high thermal stability, and residual mass. PVDF+PVA/AgNO3 membrane displayed 100% growth inhibition of both Gram-positive and Gram-negative bacteria strains, despite the wide range of fiber diameters generated, from 24 to 125 nm, formation of numerous beads, and irregular morphology. The PVDF+PVA/PC membrane showed a good growth inhibition of Staphylococcus aureus (92%) and revealed a smooth morphology with no relevant bead formations and diameters ranging from 68 to 131 nm. The ultrafiltration abilities of the membrane containing PVA/PC were tested in a dead-end high-pressure cell (4 bar) using a reactive dye in distilled water and seawater. After 5 cycles, a maximum rejection of ≈85% with an average flux rate of 70 L m-2 h-1 for distilled water and ≈64% with an average flux rate of 62 L m-2 h-1 for seawater were determined with an overall salt rejection of ≈5%.

WITHDRAWN: Hydraulic sediment penetration and seasonal growth of petalonamean basal discs from the Vendian of Ukraine

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Three Cambrian fossils assembled into an extinct body plan of cnidarian affinity

The early Cambrian problematica Xianguangia sinica, Chengjiangopenna wangii, and Galeaplumosus abilus from the Chengjiang biota (Yunnan, China) have caused much controversy in the past and their phylogenetic placements remain unresolved. Here we show, based on exceptionally preserved material (85 new specimens plus type material), that specimens previously assigned to these three species are in fact parts of the same organism and propose that C. wangii and G. abilus are junior synonyms of X. sinica Our reconstruction of the complete animal reveals an extinct body plan that combines the characteristics of the three described species and is distinct from all known fossil and living taxa. This animal resembled a cnidarian polyp in overall morphology and having a gastric cavity partitioned by septum-like structures. However, it possessed an additional body cavity within its holdfast, an anchoring pit on the basal disk, and feather-like tentacles with densely ciliated pinnules arranged in an alternating pattern, indicating that it was a suspension feeder rather than a predatory actiniarian. Phylogenetic analyses using Bayesian inference and maximum parsimony suggest that X. sinica is a stem-group cnidarian. This relationship implies that the last common ancestor of X. sinica and crown cnidarians was probably a benthic, polypoid animal with a partitioned gastric cavity and a single mouth/anus opening. This extinct body plan suggests that feeding strategies of stem cnidarians may have been drastically different from that of their crown relatives, which are almost exclusively predators, and reveals that the morphological disparity of total-group Cnidaria is greater than previously assumed.

Implant retained nasal epithesis – case report

Summary Nasal defects can occur as a result of head and neck trauma, or due to partial or complete ablation or resection of the tumor in the nasal area and surroundings. Smaller defects can be reconstructed surgically while large defects are mainly reconstructed combined surgically and prosthetically. The aim of this paper was to present prosthetic reconstruction of the nasal defect by colored vinyl polysiloxane prosthesis retained with craniofacial basal disc implants. An adequate aesthetics and stability of the prosthesis was achieved during mandible and mimic muscles movements.

Small agarics in Taiwan: Mycena albopilosa sp. nov. and Gloiocephala epiphylla

BackgroundSmall agarics are poorly documented in Taiwan, with previously reported species either rudimentarily described or lacking a description or diagnosis in most cases. A survey on small agarics in a lowland forest of Taiwan revealed two species previously unrecorded.ResultsOne agaric, which is characterized mainly by white hairs overlying the pileus, a conspicuous cup-shaped basal disc surrounding the stipe, and inamyloid basidiospores, fits the genus Mycena and appears undescribed. It readily produced abundant basidiomata in culture in three weeks. The other agaric is Gloiocephala epiphylla, being characterized by its reduced hymenium and conspicuous pileogloeocystidia. ITS sequences from the two agarics further corroborated the identifications. Their macroscopic and microscopic features and culture morphology are described. A dichotomous key is provided to the species of Mycena reported in Taiwan.ConclusionThe Mycena species is newly described as M. albopilosa herein. Gloiocephala epiphylla is new to Taiwan, being the only species of the genus known on the island.

Comparative Studies on the Biological Glue of Some Opportunistic Adult Marine Macro-Fouling After Dislodgement and Construction of Temporary Faunal Conglomerations

Comparative Studies on the Biological Glue of Some Opportunistic Adult Marine Macro-Fouling After Dislodgement and Construction of Temporary Faunal Conglomerations This study aimed to elucidate the composition of the biological glue of the sea anemone Metridium senile, the tubeworm Serpula vermicularis, the acorn barnacle Balanus amphitrite, the gastropod limpet Patella aspera and the sea squirt Styela plicata and to analyze these biological glue in the different seasons of the year. Furthermore, to propose antifouling strategies that can be developed from the present results. The sessile macro-fouling have the capability to dislodge and crawl searching for new suitable substrata for attachment. A total of 30 taxa representing five phyla were sampled every season across Northern Khobar estuarine beach of the Arabian Gulf. The proximate compositions of protein, lipid and carbohydrate in the basal discs or attachment integuments were measured using the Folin-Ciocalteu Phenol method of 66 Lowry et al., the chloroform-methanol method according to Folch et al. and the phenol-sulfuric acid method of Dubois et al. respectively. The total fat, protein, carbohydrate, and moisture contents ranged from 1 ± 0.57% -2 ± 0.98%, 23 ± 1.60 -23 ± 0.80, 0,2 ± 0,10 -1,98 ± 0,20 and 71 ± 0.61% -72 ± 2.07% by weight, respectively. The indispensable and conditional amino acids predominated in tissues were estimated. A high-pressure chromatographic separation was applied for amino acid analysis of biological glue. The most predominant amino acids were Aspartic acid (Asp D), Glutamine (Gln Q), Glycine (Gly G), Methionine (Met M), Phenylalanine (Phe F), Serine (Ser S) and Valine (Val V). Proteins in biological glue of the five species were resolved by SDS-PAGE and digested with trypsin. The majority of the resolved protein spots were within the molecular size ranging from 250 kDa to less than 30-kDa. The total lipid was estimated by chloroform-methanol method according to Folch et al. Capillary gas chromatography was applied to measure the fatty acid profiles of the biological glue. The lipid content of the biological glue of the five species studied were roughly similar but in different quantities. It was found that lipids of biological glue were predominant by C18:1 V-5, C18:2 V-6, C19:1 v- 8, C20:1 V-9, C24:1 V-6, C19:2 V-6. The estimation of total carbohydrate content of tissue in the basal discs or attachment integuments of the five macro-benthos ranged from 2.5 to 8.7 mg carbohydrates g-1 wet weight. The carbohydrate content of the biological glue was apparently dependent partly on species and partly on the season of settlement. All data obtained were statistically analyzed using One-way analysis of variance (ANOVA) of means with significance at P 0.05; Tukey's Multiple Comparison Test Mean Difference at P>0.05, P 0.05.

YelA, a putative Dictyostelium translational regulator, acts as antagonist of DIF-1 signaling to control cell-type proportioning.

DIF-1 (differentiation-inducing factor1) is a polyketide produced by Dictyostelium prespore cells which induces initially uncommitted cells to differentiate as prestalk cells. Exposure of cells to DIF-1 causes transitory hypo-phosphorylation of seven serine residues in YelA, a protein with a region of strong homology to the MIF4G domain of the eukaryotic initiation factor eIF4G. Based upon its domain architecture, which in one important aspect closely resembles that of Death-Associated Protein 5 (DAP5), we predict a role in stimulating internal ribosome entry-driven mRNA translation. The two paradigmatic DIF-1 inducible genes are ecmA (extracellular matrixA) and ecmB. In support of a YelA function in DIF-1 signaling, a YelA null strain showed greatly increased expression of ecmA and ecmB in response to DIF-1. Also, during normal development in the null strain, expression of the two genes is accelerated. This is particularly evident for ecmB, a marker of stalk tube and supporting structure differentiation. Mutants in DIF-1 bio-synthesis or signaling display a rudimentary or no basal disc and, conversely, YelA null mutants produce fruiting bodies with a highly enlarged basal disc that ectopically expresses a stalk tube-specific marker. Thus YelA acts as an antagonist of DIF-1 signaling, with a consequent effect on cell type proportioning and it is predicted to act as a translational regulator.