Evolution of the Rho guanine nucleotide exchange factors Kalirin and Trio and their gene expression in Xenopus development

Guanine nucleotide exchange factors (GEFs) activate Rho GTPases by accelerating their GDP/GTP exchange. Trio and its paralog Kalirin (Kalrn) are unique members of the Rho-GEFs that harbor three catalytic domains: two functional GEF domains and a serine/threonine kinase domain. The N-terminal GEF domain activates Rac1 and RhoG GTPases, while the C-terminal GEF domain acts specifically on RhoA. Trio and Kalrn have an evolutionary conserved function in morphogenetic processes including neuronal development. De novo mutations in TRIO have lately been identified in patients with intellectual disability, suggesting that this protein family plays an important role in development and disease. Phylogenetic and domain analysis revealed that a Kalrn/Trio ancestor originated in Prebilateria and duplicated in Urbilateria to yield Kalrn and Trio. Only few taxa outside the vertebrates retained both of these highly conserved proteins. To obtain first insights into their redundant or distinct functions in a vertebrate model system, we show for the first time a detailed comparative analysis of trio and kalrn expression in Xenopus laevis development. The mRNAs are maternally transcribed and expression increases starting with neurula stages. Trio and kalrn are detected in mesoderm/somites and different neuronal populations in the neural plate/tube and later also in the brain. However, only trio is expressed in migrating neural crest cells, while kalrn expression is detected in the cranial nerves, suggesting distinct functions. Thus, our expression analysis provides a good basis for further functional studies.

Bud detachment in hydra requires activation of fibroblast growth factor receptor and a Rho-ROCK-myosin II signaling pathway to ensure formation of a basal constriction

Background:Hydra propagates asexually by exporting tissue into a bud, which detaches 4 days later as a fully differentiated young polyp. Prerequisite for detachment is activation of fibroblast growth factor receptor (FGFR) signaling. The mechanism which enables constriction and tissue separation within the monolayered ecto‐ and endodermal epithelia is unknown. Results: Histological sections and staining of F‐actin by phalloidin revealed conspicuous cell shape changes at the bud detachment site indicating a localized generation of mechanical forces and the potential enhancement of secretory functions in ectodermal cells. By gene expression analysis and pharmacological inhibition, we identified a candidate signaling pathway through Rho, ROCK, and myosin II, which controls bud base constriction and rearrangement of the actin cytoskeleton. Specific regional myosin phosphorylation suggests a crucial role of ectodermal cells at the detachment site. Inhibition of FGFR, Rho, ROCK, or myosin II kinase activity is permissive for budding, but represses myosin phosphorylation, rearrangement of F‐actin and constriction. The young polyp remains permanently connected to the parent by a broad tissue bridge. Conclusions: Our data suggest an essential role of FGFR and a Rho‐ROCK‐myosin II pathway in the control of cell shape changes required for bud detachment. Developmental Dynamics 246:502–516, 2017. © 2017 The Authors Developmental Dynamics published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists

Hydra bud detachment involves the separation of two intact epithelia without cell death.

Remarkable cell shape changes and multicellular rosettes at the bud base indicate functional specification and strong mechanical forces.

mRNA colocalization, phospho‐myosin analysis and similar phenotypes obtained by pharmacological inhibition suggest a tight correlation between FGFR and a Rho‐ROCK‐Myosin II candidate signaling pathway.

FGFR-ERK signaling is an essential component of tissue separation

Formation of a constriction and tissue separation between parent and young polyp is a hallmark of the Hydra budding process and controlled by fibroblast growth factor receptor (FGFR) signaling. Appearance of a cluster of cells positive for double phosphorylated ERK (dpERK) at the late separation site indicated that the RAS/MEK/ERK pathway might be a downstream target of the Hydra Kringelchen FGFR. In fact, inhibition of ERK phosphorylation by the MEK inhibitor U0126 reversibly delayed bud detachment and prevented formation of the dpERK-positive cell cluster indicating de novo-phosphorylation of ERK at the late bud base. In functional studies, a dominant-negative Kringelchen FGFR prevented bud detachment as well as appearance of the dpERK-positive cell cluster. Ectopic expression of full length Kringelchen, on the other hand, induced a localized rearrangement of the actin cytoskeleton at sites of constriction, localized ERK-phosphorylation and autotomy of the body column. Our data suggest a model in which (i) the Hydra FGFR targets, via an unknown pathway, the actin cytoskeleton to induce a constriction and (ii) FGFR activates MEK/ERK signaling at the late separation site to allow tissue separation.

Phylogenomics reveals an anomalous distribution of USP genes in metazoans

Members of the universal stress protein (USP) family were originally identified in stressed bacteria on the basis of a shared domain, which has since been reported in a phylogenetically diverse range of prokaryotes, fungi, protists, and plants. Although not previously characterized in metazoans, here we report that USP genes are distributed in animal genomes in a unique pattern that reflects frequent independent losses and independent expansions. Multiple USP loci are present in urochordates as well as all Cnidaria and Lophotrochozoa examined, but none were detected in any of the available ecdysozoan or non-urochordate deuterostome genome data. The vast majority of the metazoan USPs are short, single-domain proteins and are phylogenetically distinct from the prokaryotic, plant, protist, and fungal members of the protein family. Whereas most of the metazoan USP genes contain introns, with few exceptions those in the cnidarian Hydra are intronless and cluster together in phylogenetic analyses. Expression patterns were determined for several cnidarian USPs, including two genes belonging to the intronless clade, and these imply diverse functions. The apparent paradox of implied diversity of roles despite high overall levels of sequence (and implied structural) similarity parallels the situation in bacteria. The absence of USP genes in ecdysozoans and most deuterostomes may be a consequence of functional redundancy or specialization in taxon-specific roles.

Total nucleotide analysis of Hydra DNA and RNA by MEKC with LIF detection and 32P-postlabeling

The model organism Hydra has been used for molecular studies for more than 20 years, however, its DNA base composition has not been determined yet. We have analyzed DNA and total RNA of the freshwater polyp Hydra magnipapillata with two independent procedures of high accuracy and sensitivity - fluorescence labeling of nucleotides followed by CE-LIF detection and (32)P-postlabeling. DNA of Hydra was digested either to deoxyribonucleoside-5'-monophosphates or deoxyribonucleoside-3'-monophosphates selectively conjugated with the fluorescent dye 4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-propionyl ethylene diamine hydrochloride (BODIPY FL EDA) separated and detected using CE-LIF. Both versions of the assay revealed a high A+T composition of 78 and 71%, whereas total DNA methylation (5-methyldeoxycytidine) was 2.6 and 3.1%. Total Hydra RNA showed highest base levels for guanine (33%) and a level of 1.4% for pseudouracil. All values were in good agreement with those determined by the (32)P-postlabeling method.

Conserved intron positions in FGFR genes reflect the modular structure of FGFR and reveal stepwise addition of domains to an already complex ancestral FGFR

We have analyzed the evolution of fibroblast growth factor receptor (FGFR) tyrosine kinase genes throughout a wide range of animal phyla. No evidence for an FGFR gene was found in Porifera, but we tentatively identified an FGFR gene in the placozoan Trichoplax adhaerens. The gene encodes a protein with three immunoglobulin-like domains, a single-pass transmembrane, and a split tyrosine kinase domain. By superimposing intron positions of 20 FGFR genes from Placozoa, Cnidaria, Protostomia, and Deuterostomia over the respective protein domain structure, we identified ten ancestral introns and three conserved intron groups. Our analysis shows (1) that the position of ancestral introns correlates to the modular structure of FGFRs, (2) that the acidic domain very likely evolved in the last common ancestor of triploblasts, (3) that splicing of IgIII was enabled by a triploblast-specific insertion, and (4) that IgI is subject to substantial loss or duplication particularly in quickly evolving genomes. Moreover, intron positions in the catalytic domain of FGFRs map to the borders of protein subdomains highly conserved in other serine/threonine kinases. Nevertheless, these introns were introduced in metazoan receptor tyrosine kinases exclusively. Our data support the view that protein evolution dating back to the Cambrian explosion took place in such a short time window that only subtle changes in the domain structure are detectable in extant representatives of animal phyla. We propose that the first multidomain FGFR originated in the last common ancestor of Placozoa, Cnidaria, and Bilateria. Additional domains were introduced mainly in the ancestor of triploblasts and in the Ecdysozoa.

Selective adsorption, bound states, and potential parameters for He, Ne, and Ar interacting with a Cu(110) surface

Using nozzle beams of He, Ne, and Ar, we have measured diffractive selective adsorption resonances from a Cu(110) surface kept at 20 K. Bound state energies of the atom-surface potentials have been determined from plots of the measured resonance energies versus incident angle and their fits to calculated kinematical dispersion relations. For 3He and 4He we have found a unique level assignment that is compatible with a single gas-surface potential curve with a well depth of 6.05 meV of the He-Cu(110) potential. This value is about 10% larger than the prediction of 5.55 meV from the current physisorption theory. The Ne and Ar data reveal a large number of closely spaced levels with level separations and estimated van der Waals coefficients that are compatible with available theoretical data.

cisRED: a database system for genome-scale computational discovery of regulatory elements

We describe cisRED, a database for conserved regulatory elements that are identified and ranked by a genome-scale computational system (www.cisred.org). The database and high-throughput predictive pipeline are designed to address diverse target genomes in the context of rapidly evolving data resources and tools. Motifs are predicted in promoter regions using multiple discovery methods applied to sequence sets that include corresponding sequence regions from vertebrates. We estimate motif significance by applying discovery and post-processing methods to randomized sequence sets that are adaptively derived from target sequence sets, retain motifs with p-values below a threshold and identify groups of similar motifs and co-occurring motif patterns. The database offers information on atomic motifs, motif groups and patterns. It is web-accessible, and can be queried directly, downloaded or installed locally.

Signalling by the FGFR-like tyrosine kinase, Kringelchen, is essential for bud detachment in Hydra vulgaris

Signalling through fibroblast growth factors (FGFR) is essential for proper morphogenesis in higher evolved triploblastic organisms. By screening for genes induced during morphogenesis in the diploblastic Hydra, we identified a receptor tyrosine kinase (kringelchen) with high similarity to FGFR tyrosine kinases. The gene is dynamically upregulated during budding, the asexual propagation of Hydra. Activation occurs in body regions, in which the intrinsic positional value changes. During tissue displacement in the early bud, kringelchen RNA is transiently present ubiquitously. A few hours later – coincident with the acquisition of organiser properties by the bud tip – a few cells in the apical tip express the gene strongly. About 20 hours after the onset of evagination, expression is switched on in a ring of cells surrounding the bud base, and shortly thereafter vanishes from the apical expression zone. The basal ring persists in the parent during tissue contraction and foot formation in the young polyp, until several hours after bud detachment. Inhibition of bud detachment by head regeneration results in severe distortion, disruption or even complete loss of the well-defined ring-like expression zone. Inhibition of FGFR signalling by SU5402 or, alternatively, inhibition of translation by phosphorothioate antisense oligonucleotides inhibited detachment of buds, indicating that, despite the dynamic expression pattern,the crucial phase for FGFR signalling in Hydra morphogenesis lies in bud detachment. Although Kringelchen groups with the FGFR family, it is not known whether this protein is able to bind FGFs, which have not been isolated from Hydra so far.

Reactivation of developmental programs: the cAMP-response element-binding protein pathway is involved in hydra head regeneration

Hydra regenerate throughout their life. We previously described early modulations in cAMP-response element-binding protein (CREB) DNA-binding activity during regeneration. We now show that the Ser-67 residue located in the P-box is a target for post-translational regulation. The antihydra CREB antiserum detected CREB-positive nuclei distributed in endoderm and ectoderm, whereas the phosphoSer133-CREB antibody detected phospho-CREB-positive nuclei exclusively in endodermal cells. During early regeneration, we observed a dramatic increase in the number of phospho-CREB-positive nuclei in head-regenerating tips, exceeding 80% of the endodermal cells. We identified among CREB-binding kinases the p80 kinase, which showed an enhanced activity and a hyperphosphorylated status during head but not foot regeneration. According to biochemical and immunological evidence, this p80 kinase belongs to the Ribosomal protein S6 kinase family. Exposure to the U0126 mitogen-activated protein kinase kinase inhibitor inhibited head but not foot regeneration, abolished CREB phosphorylation and activation of the early gene HyBra1 in head-regenerating tips. These data support a role for the mitogen-activated protein kinase/ribosomal protein S6 kinase/CREB pathway in hydra head organizer activity.

Nonaqueous capillary electrophoresis: a versatile completion of electrophoretic separation techniques

Nonaqueous capillary electrophoresis (NACE) is the application of a conductive electrolyte dissolved in either one organic solvent or a mixture of several organic solvents to carry out zone electrophoresis or related techniques in fused-silica capillaries. A complete review on the fundamentals, the optimization of analytical methods, practical considerations, and applications is given. To explain the differences to CE in aqueous media, a brief summary on solvent properties and molecular interactions in solutions introduces the reader into these fields. The use of additives to tune separation selectivity by means beyond a pure zone-electrophoretic mechanism is discussed in detail for organic media. Special detection techniques providing high potential for NACE are presented. Data on the precision of NACE methods and a list of relevant applications are included. More specialized applications like the determination of physicochemical constants in NACE or the setup of a semipreparative mode are described.

[Stewart-Treves syndrome arising in post-traumatic lymphedema]

The authors report a case-history of lymphangiosarcoma or Stewart-Treves syndrome which occurred in a patient with posttraumatic lymphedema of the arm. He presented two recurrences after surgery which led to the decision of amputation. He is now disease free nine years after this treatment. Initially defined as "lymphangiosarcoma arising in chronic lymphedematous extremities after mastectomy for breast cancer", Stewart-Treves syndrome complicates rarely traumatic, postsurgical, postradiation, idiopathic, congenital or filarial lymphedema. Clinical diagnosis is based on nodular, purple and frequently multiple skin lesions on chronic lymphedema of the limb. A proliferating malignant endothelium with affinity for anti-factor-VIII is found on histological slides. The tumor aggressivity explains the short survival if no treatment is given. Stewart-Treves syndrome prognosis is poor, with the occurrence of multiple local recurrences and pulmonary metastasis. On account of its rarity, there is no therapeutic consensus. In localized stage, radical surgery is usually performed. Conservative treatment with complete tumour removal and postoperative radiotherapy has not been yet evaluated. In metastatic or locally advanced tumours, it is necessary to study the benefit of cytotoxic drugs like anthacyclins and ifosfamide known to be effective on soft tissue sarcomas.

Upregulation of a Hydra vulgaris cPKC gene is tightly coupled to the differentiation of head structures

Two different cDNA clones from Hydra (HvPKC1a and HvPKC1b) were characterized, which encode members of the cPKC family of protein kinase Cs (PKCs). The two predicted proteins differ only in their amino-terminal sequences and thus probably represent the products of alternatively spliced mRNAs from a single gene. In situ hybridization with a probe recognizing sequences in common between the two mRNAs detects HvPKC1 RNA in all parts of the adult polyp except the foot. The mRNA is contained in ecto- and endodermal epithelial cells as well as a certain subset of gland cells and pairs of interstitial cells. During head and foot formation, induced by either regeneration, budding, lithium treatment or repeated application of a diacylglycerol, HvPKC1 expression is upregulated immediately prior to the evagination of tentacles and downregulated by foot formation. Although PKC activity is clearly inducible in vitro by diacylglycerol and a tumour promoting phorbol ester, structural features detected in the regulatory domains of HvPKC1a and 1b indicate that endogenous activators for Hydra PKC might differ from those of other organisms. The results corroborate the hypothesis that signal transduction systems using protein kinase C are key elements controlling the formation of head structures in Hydra.

Hydroperoxides mediate lithium effects on regeneration in Hydra

Regeneration experiments in Hydra have shown that lithium long-term treatment apparently causes a transformation of prospective head into foot tissue. Although lithium ions are known to interfere with the PI-PKC signal-transduction system and evidence has been provided that this system plays a role in pattern formation in Hydra, its role in mediating the lithium effect on patterning is still obscure. The present study provides evidence that H2O2 and presumably also lipid hydroperoxides mediate the lithium effects. First, the perturbation of pattern formation is strikingly stronger in the strain Hydra vulgaris than in Hydra magnipapillata, and similar strain-specific differences are found in the long lasting accumulation of hydroperoxides following lithium treatment. Second, the antioxidant vitamins E and C, which suppress peroxide accumulation, and the H2O2-degrading enzyme catalase significantly protect H. vulgaris from lithium effects. Lithium treatment also negatively affects overall DNA synthesis in a similar strain-specific manner, which, however, cannot be rescued by antioxidant vitamins. The lithium-activated source of peroxide production differs from another source, which generates peroxide in untreated polyps of both strains. The results suggest that lithium treatment-induced peroxide accumulation in H. vulgaris provokes a cytotoxic response showing foot-like characteristics. Nevertheless, a role of peroxides as messengers in pattern forming processes can not be excluded.

The level of expression of a protein kinase C gene may be an important component of the patterning process in Hydra

Several studies have provided strong, but indirect evidence that signalling through pathways involving protein kinase C (PKC) plays an important role in morphogenesis and patterning in Hydra. We have cloned a gene (HvPKC2) from Hydra vulgaris which encodes a member of the nPKC subfamily. In adult polyps, HvPKC2 is expressed at high levels in two locations, the endoderm of the foot and the endoderm of the hypostomal tip. Increased expression of HvPKC2 is an early event during head and foot regeneration, with the rise in expression being restricted to the endodermal cells underlying the regenerating ends. No upregulation is observed if regenerates are cut too close to the head to form a foot. Elevated expression of HvPKC2 is also observed in the endoderm underlying lithium-induced ectopic feet. A dynamic and complex pattern of expression is seen in developing buds. Regeneration of either head or foot is accompanied by an increase in the amount of PKC in both soluble and particulate fractions. An increase in the fraction of PKC activity which is membrane-bound is specifically associated with head regeneration. Taken together these data suggest that patterning of the head and foot in Hydra is controlled in part by the level of HvPKC2 expression, whilst head formation is accompanied by an in vivo activation of both calcium-dependent and independent PKC isoforms.

Stepwise transfer from high to low lithium concentrations increases the head-forming potential in Hydra vulgaris and possibly activates the PI cycle

Lithium ions affect pattern formation in the freshwater polyp Hydra vulgaris in a complex manner. Although a long-term treatment with 1 mM LiCl completely suppresses both head formation and budding, a reduction of the lithium concentration during a long-term treatment from 4 to 1 mM LiCl strongly promotes the differentiation of ectopic head structures. Meanwhile, budding, often interpreted as a special case of head formation, remains suppressed. The appearance of ectopic tentacles under these conditions is surprising as they develop while the animals remain in the presence of 1 mM LiCl, a concentration which would normally suppress the formation of tentacles. On a molecular level, the induction of ectopic head structures by the shift in the LiCl concentration is preceded by an increase in the level of inositol phosphates, indicating an activation of the phosphatidylinositol (PI) cycle. Increased inositol phosphate levels persist for at least 24 hr. Our results provide evidence that (i) tentacle- and bud-forming systems need different and possibly mutually exclusive physiological preconditions and (ii) prolonged inhibition of the PI cycle after initial activation might be necessary to obtain ectopic tentacles.

Signals and signal-transduction systems in the control of development in Hydra and Hydractinia

Pattern control in Hydra has traditionally been assigned to the determining influence of morphogens and neuropeptides. However, at present, arachidonic acid and its derivative 12-S-HETE are the only identified, potential signal molecules known to promote head and bud formation. More potent factors might exist but are not yet identified. Nonetheless, it is possible to evoke the development of an almost unlimited number of supernumerary head structures and to induce ectopic foot formation by interference with the PI-PKC signal transducing system. Such an interference can also rescue the regeneration-deficient mutant reg-16. Regarding signals in the development of Hydractinia, metamorphosis is induced by an external key stimulus, i.e. a lipid derived from environmental bacteria. The reception of this stimulus involves PKC-mediated responses. Upon its reception, a neuropeptide is released as an internal, synchronising signal. Members of the novel LWamide family of peptides appear to represent this internal signal. In postmetamorphic development, a glycoprotein SIF serves as an inducer of stolon formation.

Pattern formation in Hydra vulgaris is controlled by lithium-sensitive processes

Application of lithium ions leads to dramatic alterations in the positional value and subsequently to the formation of ectopic foot or head structures in Hydra vulgaris. Prolonged LiCl treatment decreases and pulse treatment increases the positional value. The decrease in the positional value is manifested in the formation of multiple ectopic feet along the body axis of intact animals or regenerates. Regeneration experiments reveal that long term application of the ion leads to transformation of prospective head into foot tissue. This transformation requires lithium pretreatment and exposure of the excised pieces to lithium for a further 5-8 hr. Pulse treatment of hydra with lithium elevates the positional value. Regenerating distal thirds differentiate ectopic head structures instead of a foot. Changes in the lithium concentration during the experiment lead to the differentiation of ectopic heads in the upper as well as ectopic feet in the lower body region. The characteristics of pattern respecification presented in this paper suggest that lithium interferes with the main pattern forming system(s) in hydra.

Pharmacokinetics of N-nitrodimethylamine and N-nitromethylamine in the rat

Oxidative metabolism of radioactively labeled N-nitrodimethylamine in rats was compared with that of N-nitromethylamine. Within 7 h, 20% of N-nitrodimethylamine was metabolized to CO2 but only 4% of N-nitromethylamine. The poor oxidative metabolism of N-nitromethylamine is also reflected in the blood levels determined after i.v. administration to catheterized rats. N-Nitrodimethylamine was cleared rapidly from rat blood, while N-nitromethylamine was rapidly distributed into body water but had a long elimination half-life. An amount equal to 5.2% of the dose of the monomethyl compound was excreted intact in urine, but only 0.004% of the dimethyl compound. The pharmacokinetic data obtained were compared with the published data on the pharmacokinetics of the structural analog N-nitrosodimethylamine.

[Electrophysiologic findings in lacunar infarcts]

Lacunar lesions are small infarctions in the territory of small penetrating arteries of the brain. Because of their small size these lesions can only in part be detected by CT. Clinical symptoms do not always correspond with the lesions visible in the CT. We studied the somatosensory evoked potentials (SEP), the visual evoked potentials (VEP) and the electrically elicited blink reflex in 50 patients with lacunes to determine if there are any other lesions which are not detectable by clinical examination or CT alone. While VEP and the blink reflex showed pathological results in only a few of these patients the SEP were pathological in about 75%. The multiplicity of the lesions may be documented by means of these investigations.

ATP-ADP-dependent phosphorylations of glycolysis metabolites, creatine and glycerol: their compartition and thermodynamic relationship in gastrocnemius muscle cell of exercised guinea pigs

The concentrations of following metabolites were determined in freeze-clamped gastrocnemius muscle samples: glucose 1-phosphate, glucose 6-phosphate, glucose, fructose 1,6-diphosphate, fructose 6-phosphate, D-glyceraldehyde 3-phosphate. dihydroxyacetone phosphate, phosphoenolpyruvate, pyruvate, glycerol 3-phosphate, glycerol, creatine phosphate, creatine, glycerate 3-phosphate, glycerate 2-phosphate, adenosine monophosphate, adenosine diphosphate, adenosine triphosphate, inorganic phosphate. The results showed that within the limits of experimental error, concentration homeostasis for this metabolites is founded at least in some cases on equilibria between enzymic transformations. Discrepancies between constant mass ratios measured in this study and equilibrium constants allow the free energy variation delta G to keep creatine phosphate at high concentration to be calculated. For the phosphoglycerate mutase system, the equilibrium constant in controls and trained animals is unchanged and corresponds to that in vitro. Training hindered glycolysis and favoured phosphorylation of creatine by glycerol 3-phosphate. Metabolites of the pyruvate kinase and hexokinase system cannot be homogeneously distributed in one space. The creatine kinase system is also separated from the hexokinase und pyruvate kinase system. A compartition of glycolytic process in gastrocnemius muscle seems to be inferred from these results.

[Local fibrinolysis therapy in subtotal stenosis of the median cerebral artery]

In a 60-year-old female patient with clinical symptoms of progressive left-sided apoplexia and subtotal stenosis of the middle cerebral artery local fibrinolysis via a floating balloon catheter was successfully used for recanalisation of the vessel leading to marked clinical improvement.