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Papers by Michael Saina

BMC Biology

Background The nose of most animals comprises multiple sensory subsystems, which are defined by t... more Background The nose of most animals comprises multiple sensory subsystems, which are defined by the expression of different olfactory receptor families. Drosophila melanogaster antennae contain two morphologically and functionally distinct subsystems that express odorant receptors (Ors) or ionotropic receptors (Irs). Although these receptors have been thoroughly characterized in this species, the subsystem-specific expression and roles of other genes are much less well-understood. Results Here we generate subsystem-specific transcriptomic datasets to identify hundreds of genes, encoding diverse protein classes, that are selectively enriched in either Or or Ir subsystems. Using single-cell antennal transcriptomic data and RNA in situ hybridization, we find that most neuronal genes—other than sensory receptor genes—are broadly expressed within the subsystems. By contrast, we identify many non-neuronal genes that exhibit highly selective expression, revealing substantial molecular hete...

Acta Materialia, 2000

Stoichiometric Nd 2 (Fe 1Ϫx Co x) 14 B alloys (x ϭ 0, 0.25, 0.5, 0.75 and 1) have been disproport... more Stoichiometric Nd 2 (Fe 1Ϫx Co x) 14 B alloys (x ϭ 0, 0.25, 0.5, 0.75 and 1) have been disproportionated into NdH 2ϩδ and bcc-(Fe,Co) (0ՅxՅ0.75) or fcc-Co (x ϭ 1), respectively, by milling in hydrogen at enhanced temperatures. Reactive milling leads to the disproportionation of the thermodynamically very stable Nd 2 Co 14 B alloy. This reaction is not possible via the conventional hydrogenation disproportionation desorption and recombination (HDDR) process. Grain sizes of disproportionated and recombined Nd 2 (Fe,Co) 14 B materials were found to be Ͻ10 nm and 40-50 nm, respectively-approximately an order of magnitude smaller than those of conventional-HDDR processed alloys. The recombined Nd 2 Co 14 B alloy shows on average slightly smaller grain sizes than the Nd 2 Fe 14 B compound. A more effective exchange coupling leading to enhanced remanences, possibly due to the slightly smaller grain size, has been observed for Nd 2 Co 14 B powders recombined at 600-700°C.

Developmental Biology, 2006

The evolutionary origin of the anterior-posterior and the dorsoventral body axes of Bilateria is ... more The evolutionary origin of the anterior-posterior and the dorsoventral body axes of Bilateria is a long-standing question. It is unclear how the main body axis of Cnidaria, the sister group to the Bilateria, is related to the two body axes of Bilateria. The conserved antagonism between two secreted factors, BMP2/4 (Dpp in Drosophila) and its antagonist Chordin (Short gastrulation in Drosophila) is a crucial component in the establishment of the dorsoventral body axis of Bilateria and could therefore provide important insight into the evolutionary origin of bilaterian axes. Here, we cloned and characterized two BMP ligands, dpp and GDF5-like as well as two secreted antagonists, chordin and gremlin, from the basal cnidarian Nematostella vectensis. Injection experiments in zebrafish show that the ventralizing activity of NvDpp mRNA is counteracted by NvGremlin and NvChordin, suggesting that Gremlin and Chordin proteins can function as endogenous antagonists of NvDpp. Expression analysis during embryonic and larval development of Nematostella reveals asymmetric expression of all four genes along both the oral-aboral body axis and along an axis perpendicular to this one, the directive axis. Unexpectedly, NvDpp and NvChordin show complex and overlapping expression on the same side of the embryo, whereas NvGDF5-like and NvGremlin are both expressed on the opposite side. Yet, the two pairs of ligands and antagonists only partially overlap, suggesting complex gradients of BMP activity along the directive axis but also along the oral-aboral axis. We conclude that a molecular interaction between BMP-like molecules and their secreted antagonists was already employed in the common ancestor of Cnidaria and Bilateria to create axial asymmetries, but that there is no simple relationship between the oral-aboral body axis of Nematostella and one particular body axis of Bilateria.

The nose of most animals comprises multiple sensory subsystems, which are defined by the expressi... more The nose of most animals comprises multiple sensory subsystems, which are defined by the expression of different olfactory receptor families. Drosophila melanogaster antennae comprise two morphologically and functionally distinct subsystems that express Odorant receptors (Ors) or Ionotropic receptors (Irs). Although these receptors have been thoroughly characterized in this species, the subsystem-specific expression and roles of other genes are much less well-understood. Here we generate subsystem-specific transcriptomic datasets to identify hundreds of genes, encoding diverse protein classes, that are selectively enriched in either Or or Ir subsystems. Using single-cell antennal transcriptomic data and RNA in situ hybridization, we find most neuronal genes – other than sensory receptor genes – are broadly expressed within the subsystems. By contrast, we identify many non-neuronal genes that exhibit highly selective cell-type expression, revealing substantial molecular heterogeneity...

complexity and non-metazoan genes in two basal cnidarians

Nature Communications, 2015

Insect Gustatory and Odorant Receptors (GRs and ORs) form a superfamily of novel transmembrane pr... more Insect Gustatory and Odorant Receptors (GRs and ORs) form a superfamily of novel transmembrane proteins, which are expressed in chemosensory neurons that detect environmental stimuli. Here we identify homologues of GRs (Gustatory receptor-like (Grl) genes) in genomes across Protostomia, Deuterostomia and non-Bilateria. Surprisingly, two Grls in the cnidarian Nematostella vectensis, NvecGrl1 and NvecGrl2, are expressed early in development, in the blastula and gastrula, but not at later stages when a putative chemosensory organ forms. NvecGrl1 transcripts are detected around the arboral pole, considered the equivalent to the head-forming region of Bilateria. Morpholino-mediated knockdown of NvecGrl1 causes developmental patterning defects of this region, leading to animals lacking the apical sensory organ. A deuterostome Grl from the sea urchin Strongylocentrotus purpuratus displays similar patterns of developmental expression. These results reveal an early evolutionary origin of the insect chemosensory receptor family, and raise the possibility that their ancestral role was in embryonic development. Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:

Methods in Molecular Biology, 2013

Odor detection and discrimination by olfactory systems in vertebrates and invertebrates depend bo... more Odor detection and discrimination by olfactory systems in vertebrates and invertebrates depend both on the selective expression of individual olfactory receptor genes in subpopulations of olfactory sensory neurons, and on the targeting of the encoded proteins to the exposed, ciliated endings of sensory dendrites. Techniques to visualize the expression and localization of olfactory receptor gene products in vivo have been essential to reveal the molecular logic of peripheral odor coding and to permit investigation of the developmental and cellular neurobiology of this sensory system. Here, we describe methods for detection of olfactory receptor transcripts and proteins in the antennal olfactory organ of the fruit fly, Drosophila melanogaster, an important genetic model organism. We include protocols both for antennal cryosections and whole-mount antennae. These methods can be adapted for detection of receptor expression in other olfactory and gustatory tissues in Drosophila, as well as in the chemosensory systems of other insects.

Proceedings of the National Academy of Sciences, 2009

Journal of Experimental Zoology Part B: Molecular and Developmental Evolution, 2009

The signaling molecule Myostatin, a member of the TGF-b superfamily, is crucially involved in the... more The signaling molecule Myostatin, a member of the TGF-b superfamily, is crucially involved in the control of muscle growth and development in triploblastic organisms. A homolog to vertebrate myostatin and gdf8/11 was isolated from a diploblastic cnidarian, the starlet sea anemone Nematostella vectensis. Here we provide a detailed characterization of the Nematostella myostatin/gdf8/11 gene and show the first analysis of gene expression in adult polyps. This analysis revealed that myostatin/gdf8/11 is expressed in the mesenteries, which are endodermal folds, and weakly in the body wall endoderm, but largely excluded from the areas of muscle formation, the retractor and the parietal muscle. Contrary to this, in vertebrates the muscle growth inhibitor myostatin is expressed in the muscle tissue. We therefore hypothesize that myostatin/gdf8/11 in Nematostella is involved in regulating nonmuscle cell differentiation, possibly by repressing muscle differentiation.

Developmental Biology, 2004

The winged helix transcription factor Forkhead and the zinc finger transcription factor Snail are... more The winged helix transcription factor Forkhead and the zinc finger transcription factor Snail are crucially involved in germ layer formation in Bilateria. Here, we isolated and characterized a homolog of forkhead/HNF3 (FoxA/group 1) and of snail from a diploblast, the sea anemone Nematostella vectensis. We show that Nematostella forkhead expression starts during late Blastula stage in a ring of cells that demarcate the blastopore margin during early gastrulation, thereby marking the boundary between ectodermal and endodermal tissue. snail, by contrast, is expressed in a complementary pattern in the center of forkhead-expressing cells marking the presumptive endodermal cells fated to ingress during gastrulation. In a significant portion of early gastrulating embryos, forkhead is expressed asymmetrically around the blastopore. While snail-expressing cells form the endodermal cell mass, forkhead marks the pharynx anlage throughout embryonic and larval development. In the primary polyp, forkhead remains expressed in the pharynx. The detailed analysis of forkhead and snail expression during Nematostella embryonic and larval development further suggests that endoderm formation results from epithelial invagination, mesenchymal immigration, and reorganization of the endodermal epithelial layer, that is, by epithelial-mesenchymal transitions (EMT) in combination with extensive morphogenetic movements. snail also governs EMT at different processes during embryonic development in Bilateria. Our data indicate that the function of snail in Diploblasts is to regulate motility and cell adhesion, supporting that the triggering of changes in cell behavior is the ancestral role of snail in Metazoa.

Developmental …, 2006

... patterning. Fabian Rentzsch a , b , Roman Anton c , d , Michael Saina a , Matthias Hammerschm... more ... patterning. Fabian Rentzsch a , b , Roman Anton c , d , Michael Saina a , Matthias Hammerschmidt b , Thomas W. Holstein c , e and Ulrich Technau a , Corresponding Author Contact Information , E-mail The Corresponding Author. ...

Trends in Genetics, 2005

Cnidarians are among the simplest extant animals; however EST analyses reveal that they have a re... more Cnidarians are among the simplest extant animals; however EST analyses reveal that they have a remarkably high level of genetic complexity. In this article, we show that the full diversity of metazoan signaling pathways is represented in this phylum, as are antagonists previously known only in chordates. Many of the cnidarian ESTs match genes previously known only in non-animal kingdoms. At least some of these represent ancient genes lost by all bilaterians examined so far, rather than genes gained by recent lateral gene transfer.