Germ Ring Research Articles

Profiling of the embryonic Atlantic halibut (Hippoglossus hippoglossus L.) transcriptome reveals maternal transcripts as potential markers of embryo quality.

BackgroundCommercial Atlantic halibut (Hippoglossus hippoglossus) farming is restricted by variable oocyte quality, slow growth, and early maturation of male fish. Maternally transferred components regulate early developmental processes; therefore, they have an effect on the future viability of the embryo. Using a newly developed Agilent 10 k custom-made oligonucleotide array, we profiled components of the transcriptome involved in immune defence as well as germline and muscle development during early developmental stages: 8-cell embryos (8CS), germ ring stage (GR), 10-somite stage (10SS), and hatched embryos (HT). In addition, we identified differentially expressed transcripts in low (≤9 ± 3% hatching) and high (≥86 ± 3°% hatching) quality eggs at 8CS to identify potential maternal markers for embryo quality.ResultsOut of 2066 differentially expressed transcripts, 160 were identified as maternal transcripts being specifically expressed at 8CS only. Twenty transcripts were differentially expressed in 8-cell embryos between low and high quality egg groups. Several immune-related transcripts were identified as promising molecular markers of hatching success including interferon regulatory factor 7 and mhc class 2A chain. Differential expression was positively validated with quantitative real-time PCR.ConclusionsWe have demonstrated maternal transfer of innate and adaptive immune system transcripts into Atlantic halibut embryos and their relation with future embryo developmental potential. We identified several transcripts as potential molecular markers of embryo quality. The developed microarray represents a useful resource for improving the commercial production of Atlantic halibut.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-829) contains supplementary material, which is available to authorized users.

An equivariant Poincaré series of filtrations and monodromy zeta functions

We define a new equivariant (with respect to a finite group $$G$$ action) version of the Poincare series of a multi-index filtration as an element of the power series ring $${\widetilde{A}}(G)[[t_1, \ldots , t_r]]$$ for a certain modification $${\widetilde{A}}(G)$$ of the Burnside ring of the group $$G$$ . We give a formula for this Poincare series of a collection of plane valuations in terms of a $$G$$ -resolution of the collection. We show that, for filtrations on the ring of germs of functions in two variables defined by the curve valuations corresponding to the irreducible components of a plane curve singularity defined by a $$G$$ -invariant function germ, in the majority of cases this equivariant Poincare series determines the corresponding equivariant monodromy zeta functions defined earlier.

A Note on the Weierstrass Preparation Theorem in Quasianalytic Local Rings

AbstractConsider quasianalytic local rings of germs of smooth functions closed under composition, implicit equation, and monomial division. We show that if theWeierstrass Preparation Theoremholds in such a ring, then all elements of it are germs of analytic functions.

Coherence and other properties of sheaves in the Kohn algorithm

In the smooth case, we prove quasi-flasqueness for the sheaves of all subelliptic multipliers as well as at each of the steps of the Kohn algorithm on a pseudoconvex domain in ℂn. We use techniques by Jean-Claude Tougeron to show that if the domain has a real-analytic defining function, the modified Kohn algorithm involving generating ideals and taking real radicals only in the ring of real-analytic germs yields quasi-coherent sheaves. This sharpens a result obtained by J. J. Kohn in 1979.

Failure of the Weierstrass Preparation Theorem in quasi-analytic Denjoy–Carleman rings

It is shown that Denjoy–Carleman quasi-analytic rings of germs of functions in two or more variables fail to satisfy the Weierstrass Preparation Theorem. The result is proven via a non-extension theorem.

Equivariant Poincaré series of filtrations and topology

Earlier, for an action of a finite group G on a germ of an analytic variety, an equivariant G-Poincaré series of a multi-index filtration in the ring of germs of functions on the variety was defined as an element of the Grothendieck ring of G-sets with an additional structure. We discuss to which extent the G-Poincaré series of a filtration defined by a set of curve or divisorial valuations on the ring of germs of analytic functions in two variables determines the (equivariant) topology of the curve or of the set of divisors.

Hilbert function, generalized Poincaré series and topology of plane valuations

To a multi-index filtration (say, on the ring of germs of functions on a germ of a complex analytic variety) one associates several invariants: the Hilbert function, the Poincare series, the generalized Poincare series, and the generalized semigroup Poincare series. The Hilbert function and the generalized Poincare series are equivalent in the sense that each of them determines the other one. We show that for a filtration on the ring of germs of holomorphic functions in two variables defined by a collection of plane valuations both of them are equivalent to the generalized semigroup Poincare series and determine the topology of the collection of valuations, i.e. the topology of its minimal resolution.

The Amotl2 Gene Inhibits Wnt/β-Catenin Signaling and Regulates Embryonic Development in Zebrafish

The Motin family proteins can regulate cell polarity, cell mobility, and proliferation during embryonic development by controlling distinct signaling pathways. In this study, we demonstrate that amotl2 knockdown in zebrafish wild-type embryos results in embryonic dorsalization, and this effect can be antagonized by co-knockdown of the dorsal inducer β-catenin2. Overexpression of amotl2 in masterblind (mbl) homozygous embryos, in which canonical Wnt signaling is up-regulated due to an axin1 mutation, transforms eyeless phenotype into smaller eyes, whereas co-knockdown of amot, amotl1, and amotl2 leads to development of smaller eyes in mbl heterozygotes. In cultured mammalian cells, Motin family members all possess the ability to attenuate Wnt/β-catenin signaling. Focusing on Amotl2, we show that Amotl2 can associate with and trap β-catenin in the Rab11-positive recycling endosomes, and as a result, the amount of β-catenin in the cytosol and nucleus is reduced. Thus, our findings provide novel insights into functions of Motin family members and regulation of Wnt/β-catenin signaling.

Alexander polynomials and Poincaré series of sets of ideals

Earlier the authors considered and, in some cases, computed Poincaré series for two sorts of multi-index filtrations on the ring of germs of functions on a complex (normal) surface singularity (in particular, on the complex plane). A filtration of the first class was defined by a curve (with several branches) on the surface singularity. A filtration of the second class (called divisorial) was defined by a set of components of the exceptional divisor of a modification of the surface singularity. Here we define and compute in some cases the Poincaré series corresponding to a set of ideals in the ring of germs of functions on a surface singularity. For the complex plane, this notion unites the two classes of filtrations described above.

Equivariant Poincaré series of filtrations

We offer a new approach to a definition of an equivariant version of the Poincare series. This Poincare series is defined not as a power series, but as an element of the Grothendieck ring of G-sets with an additional structure. We compute this Poincare series for natural filtrations on the ring of germs of functions on the plane (ℂ2,0) with a finite group representation.

On some noetherian rings of C∞germs on a real closed field

Let $R$ be a real closed field, and denote by $\mathcal{E}_{R,n}$ the ring of germs, at the origin of $R^n$, of $ C^\infty$ functions in a neighborhood of $0\in R^n$. For each $n\in\mathbb{N}$, we construct a quasianalytic subring $\mathcal{A}_{R,n}\subse

Heterochrony in the germ ring closure and tail bud formation in embryonic development of rainbow trout (Oncorhynchus mykiss)

Due to their large yolk size, salmonid embryos take a longer time for epiboly movements and germ ring closure compared with most other teleost species. Here we analyzed the germ ring closure, tail bud formation and development of the notochord and somites in rainbow trout using live embryo imaging and in situ hybridization with the rt-ntl probe. Rt-ntl is expressed in the germ ring (blastula, gastrula and somitogenesis stage), notochord, tail bud and somites (somitogenesis stage). When epiboly covers half the yolk, a tail bud-like structure is formed and somitogenesis starts. By the time epiboly is completed, the yolk covered and the germ ring closed, the embryo has already reached the 20 somite stage. Therefore, the timing of germ ring closure and tail bud formation is reversed in trout embryos compared with zebrafish and other small model fish embryos (heterochrony). Based on this result, we re-examined the definition of tail bud formation.

The Poincaré series of divisorial valuations in the plane defines the topology of the set of divisors

With a plane curve singularity one associates a multi-index filtration on the ring of germs of functions of two variables defined by the orders of a function on irreducible components of the curve. The Poincaré series of this filtration turns out to coincide with the Alexander polynomial of the curve germ. For a finite set of divisorial valuations on the ring corresponding to some components of the exceptional divisor of a modification of the plane, in a previous paper there was obtained a formula for the Poincaré series of the corresponding multi-index filtration similar to the one associated with plane germs. Here we show that the Poincaré series of a set of divisorial valuations on the ring of germs of functions of two variables defines “the topology of the set of the divisors” in the sense that it defines the minimal resolution of this set up to combinatorial equivalence. For the plane curve singularity case, we also give a somewhat simpler proof of the statement by Yamamoto which shows that the Alexander polynomial is equivalent to the embedded topology.

An elementary proof of the Briançon-Skoda theorem

We give an elementary proof of the Briançon-Skoda theorem. The theorem gives a criterionfor when a function φ belongs to an ideal I of the ring of germs of analytic functions at 0∈ℂ n ; more precisely, the ideal membership is obtained if a function associated with φ and I is locally square integrable. If I can be generated by m elements,it follows in particular that I min(m,n) ¯⊂I, where J ¯ denotes the integral closure of an ideal J.

Multi-variable Poincaré series associated with Newton diagrams

We define a multi-index filtration on the ring of germs of functions on a hypersurface singularity associated with its Newton diagram and

Homomorphism of quasianalytic local rings

Let C n \mathcal {C}_n be a local quasi-analytic subring of the ring of germs of C ∞ C^\infty functions on R n \mathbb {R}^n , and let C = { C n , n ∈ N } \mathcal {C}=\{ \mathcal {C}_n\,,\, n\in \mathbb {N}\} . We suppose that C \mathcal {C} is closed under composition. Consider a map φ : ( R n , 0 ) → ( R k , 0 ) \varphi : (\mathbb {R}^n, 0)\rightarrow (\mathbb {R}^k, 0) vanishing at zero, where φ \varphi is a k k -tuple ( φ 1 , … , φ k ) (\varphi _1,\ldots ,\varphi _k) and φ 1 , … , φ k \varphi _1,\ldots ,\varphi _k are in C n \mathcal {C}_n . Then φ \varphi defines uniquely a map ϕ : C k → C n \phi : \mathcal {C}_k \rightarrow \mathcal {C}_n by composition, and ϕ \phi induces a morphism ϕ ^ : C k ^ → C n ^ \hat {\phi }: \hat {\mathcal {C}_k }\rightarrow \hat {\mathcal {C}_n} between completions. We let ϕ ∗ : C k ^ C k → C n ^ C n \phi _* : \frac {\hat {\mathcal {C}_k} }{\mathcal {C}_k }\rightarrow \frac {\hat {\mathcal {C}_n }}{\mathcal {C}_n } be the homomorphism of groups induced by ϕ \phi and ϕ ^ \hat {\phi } in the obvious manner. In the analytic case, i.e. when each C n \mathcal {C}_n is the ring of germs of real analytic functions, M. Eakin and A. Harris give a condition under which ϕ ∗ \phi _* is injective. In this paper we prove that the same statement does not hold for a quasianalytic system unless this system is analytic.

S08-04 Multiple functions for the zinc finger transcription factor odd skipped related1 in kidney and angioblast development

The kidney and vasculature are intimately linked functionally and during development, where nephric and blood/vascular progenitor cells occupy adjacent bands of mesoderm in zebrafish and frog embryos. Developmental mechanisms underlying the differentiation of kidney vs. blood/vascular lineages are unknown. The odd skipped related1 (osr1) gene encodes a zinc finger transcription factor that is expressed in the germ ring mesendoderm and subsequently in the endoderm and intermediate mesoderm, prior to the expression of definitive kidney or blood/vascular markers. Knockdown of osr1 in zebrafish embryos resulted in a segmentspecific loss of anterior kidney progenitors and a compensatory increase in the number of angioblast cells in the same trunk region. Kidney glomeruli and proximal tubules were absent while the cardinal vein and posterior venous plexuswere expanded. Altered kidney vs. vascular development correlated with expanded endoderm development in osr1 knockdowns. Combined osr1 loss of function with blockade of endoderm development by knockdown of sox32/ casanova rescued kidney proximal tubule but not glomerular development. Absence of glomerular development correlated with osr1 co-expression with wt1 in podocyte progenitor cells. The results indicate that osr1 affects kidney proximal tubule and angioblast development by a non-cell autonomous effect mediated by endoderm while glomerular development is likely to be due to a cell-autonomous role for osr1 in podocyte progenitors.

S08-05 Regulation of microtubule organization by xMID is essential for maintaining tissue integrity in Xenopus neural tube closure

The kidney and vasculature are intimately linked functionally and during development, where nephric and blood/vascular progenitor cells occupy adjacent bands of mesoderm in zebrafish and frog embryos. Developmental mechanisms underlying the differentiation of kidney vs. blood/vascular lineages are unknown. The odd skipped related1 (osr1) gene encodes a zinc finger transcription factor that is expressed in the germ ring mesendoderm and subsequently in the endoderm and intermediate mesoderm, prior to the expression of definitive kidney or blood/vascular markers. Knockdown of osr1 in zebrafish embryos resulted in a segmentspecific loss of anterior kidney progenitors and a compensatory increase in the number of angioblast cells in the same trunk region. Kidney glomeruli and proximal tubules were absent while the cardinal vein and posterior venous plexuswere expanded. Altered kidney vs. vascular development correlated with expanded endoderm development in osr1 knockdowns. Combined osr1 loss of function with blockade of endoderm development by knockdown of sox32/ casanova rescued kidney proximal tubule but not glomerular development. Absence of glomerular development correlated with osr1 co-expression with wt1 in podocyte progenitor cells. The results indicate that osr1 affects kidney proximal tubule and angioblast development by a non-cell autonomous effect mediated by endoderm while glomerular development is likely to be due to a cell-autonomous role for osr1 in podocyte progenitors.

Odd skipped related1reveals a novel role for endoderm in regulating kidney versus vascular cell fate

The kidney and vasculature are intimately linked both functionally and during development, when nephric and blood/vascular progenitor cells occupy adjacent bands of mesoderm in zebrafish and frog embryos. Developmental mechanisms that underlie the differentiation of kidney versus blood/vascular lineages remain unknown. The odd skipped related1 (osr1) gene encodes a zinc-finger transcription factor that is expressed in the germ ring mesendoderm and subsequently in the endoderm and intermediate mesoderm, prior to the expression of definitive kidney or blood/vascular markers. Knockdown of osr1 in zebrafish embryos resulted in a complete, segment-specific loss of anterior kidney progenitors and a compensatory increase in the number of angioblast cells in the same trunk region. Histology revealed a subsequent absence of kidney tubules, an enlarged cardinal vein and expansion of the posterior venous plexus. Altered kidney versus vascular development correlated with expanded endoderm development in osr1 knockdowns. Combined osr1 loss of function and blockade of endoderm development by knockdown of sox32/casanova rescued anterior kidney development. The results indicate that osr1 activity is required to limit endoderm differentiation from mesendoderm; in the absence of osr1, excess endoderm alters mesoderm differentiation, shifting the balance from kidney towards vascular development.

Origin and shaping of the laterality organ in zebrafish

Handedness of the vertebrate body plan critically depends on transient embryonic structures/organs that generate cilia-dependent leftward fluid flow within constrained extracellular environments. Although the function of ciliated organs in laterality determination has been extensively studied, how they are formed during embryogenesis is still poorly understood. Here we show that Kupffer's vesicle (KV), the zebrafish organ of laterality, arises from a surface epithelium previously thought to adopt exclusively extra-embryonic fates. Live multi-photon confocal imaging reveals that surface epithelial cells undergo Nodal/TGFbeta signalling-dependent ingression at the dorsal germ ring margin prior to gastrulation, to give rise to dorsal forerunner cells (DFCs), the precursors of KV. DFCs then migrate attached to the overlying surface epithelium and rearrange into rosette-like epithelial structures at the end of gastrulation. During early somitogenesis, these epithelial rosettes coalesce into a single rosette that differentiates into the KV with a ciliated lumen at its apical centre. Our results provide novel insights into the morphogenetic transformations that shape the laterality organ in zebrafish and suggest a conserved progenitor role of the surface epithelium during laterality organ formation in vertebrates.