A Non-Synonymous HMGA2 Variant Decreases Height in Shetland Ponies and Other Small Horses

The identification of quantitative trait loci (QTL) such as height and their underlying causative variants is still challenging and often requires large sample sizes. In humans hundreds of loci with small effects control the heritable portion of height variability. In domestic animals, typically only a few loci with comparatively large effects explain a major fraction of the heritability. We investigated height at withers in Shetland ponies and mapped a QTL to ECA 6 by genome-wide association (GWAS) using a small cohort of only 48 animals and the Illumina equine SNP70 BeadChip. Fine-mapping revealed a shared haplotype block of 793 kb in small Shetland ponies. The HMGA2 gene, known to be associated with height in horses and many other species, was located in the associated haplotype. After closing a gap in the equine reference genome we identified a non-synonymous variant in the first exon of HMGA2 in small Shetland ponies. The variant was predicted to affect the functionally important first AT-hook DNA binding domain of the HMGA2 protein (c.83G>A; p.G28E). We assessed the functional impact and found impaired DNA binding of a peptide with the mutant sequence in an electrophoretic mobility shift assay. This suggests that the HMGA2 variant also affects DNA binding in vivo and thus leads to reduced growth and a smaller stature in Shetland ponies. The identified HMGA2 variant also segregates in several other pony breeds but was not found in regular-sized horse breeds. We therefore conclude that we identified a quantitative trait nucleotide for height in horses.     

The ultrastructure of the so-called olfactory setae on the antennula ofDaphnia magna Straus (Crustacea,Cladocera)

A group of nine sensory setae is found on the tip of the antennula ofDaphnia magna in both sexes. Inside a seta four dendrites are situated, each with one receptor cilium. The receptor cilia extend through a liquor space into the exterior part of the seta. The exterior part of the liquor space is divided from the interior part by a knob-like thickening of the innermost layer of the epicuticle, the basal bead. The basal bead narrows the liquor space and the receptor cilia. The interior part of the liquor space is surrounded by five sheath cells, the exterior part by a thin cuticle. In the exterior part the receptor cilia branch partly and reach a terminal pellet on the tip of the seta. The terminal pellet is a thickened part of the epicuticle. It is permeable to several dissolved substances. It is the exterior part of the receptor that projects over the tip of the antennula and seems to be the entire seta. During the premoult the fifth sheath cell builds up the articulation of the seta, the fourth the basal bead, and the third the shaft of the seta. The first sheath cell forms the cuticular sheath. The organ seems to be a chemoreceptor, but the adequate stimulus is as yet unknown.     

Digestion of prey in foraminifera is not anomalous: A correlation of light microscopic, cytochemical, and hvem technics to study phagotrophy in two allogromiids

Correlative light, high-voltage electron and conventional electron microscopic methods were used to investigate digestion in two allogromiid foraminiferans, Allogromia sp., strain NF, and A. laticollaris Arnold. Microscopic observations showed that bacterial prey are phagocytosed by reticulopodia and are transported to the allogromiid cell body within blister-like phagosomes. Larger prey (algae, diatoms) are transported along the reticulopodial surface and are either stored extrathalamously or phagocytosed at the oral opening (peduncle). Studies of allogromiids optimally fixed and labeled with an extracellular-space label (colloidal thorium) showed that phagocytosed prey are completely enclosed by a plasma membrane envelope; this finding was corroborated by a serial-section three-dimensional reconstruction of the oral zone of one allogromiid. Cytochemical staining for acid phosphatase showed that lysosomes are absent from reticulopods but abundant in the cell body, particularly in the oral zone cytoplasm. We conclude that digestion in allogromiid foraminiferans is accomplished by a vacuole-based digestive apparatus and not by extracellular digestion within a lacunary system, as has been suggested in earlier studies.     

Ultrastruktur und polysaccharidanteile der cuticula von Triops cancriformis Bosc. (Crustacea,Notostraca) während der Häutungsvorbereitung

Zusammenfassung Die Cuticula von Triops cancriformis besteht aus Endo-, Exo- und Epicuticula. Die Epicuticula ist aus vier Schichten aufgebaut, die Exocuticula aus 10 und die Endocuticula aus 60–80. Die Schichten der Endocuticula sind aus annähernd oberflächenparallel verlaufenden Mikrofibrillen, die zu Lamellulae zusammentreten, gebildet. Diese Lamellulae atehen senkrecht zur Oberfläche. Die Lamellulae der einzelnen Lagen verlaufen im rechten Winkel zu denen der Nachbarlagen. In Sinnesborsten verläuft so ein Teil der Fibrillen in Längsrichtung, der andere quer zur Längsachse.Polysaccharide finden sich in den Lamellulae, in zwei Schichten der Epicuticula, den Desmosomen und als Glykogengranula in Epidermiszellen.Die Häutung zeigt anscheinend keine Besonderheiten gegenüber anderen Arthropoden.

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Ultrastructure and polysaccharide content of the cuticle of Triops cancriformis Bosc. (Crustacea, Notostraca) during the Molting preparation

Summary The cuticle of Triops cancriformis consists of endo-, exo- and epicuticle. The epicuticle comprises 4 layers, the epocuticle 10 and the endocuticle 60–80 layers. The layers of the endocuticle consist of microfibrils. These microfibrils are almost parallel to the surface of the cuticle and merge into lamellulae. These lamellulae run vertical to the surface. The lamellulae in any one layer are at right angles to the lamellulae in the neighbouring layers. Thus, some of the fibrils in sensory setae are parallel to the longitudinal axis and others are perpendicular to it.Polysaccharides are found in the lamellulae, in two layers of the epicuticle, in the attachment regions and in the glycogen deposits in the epidermis cells.The molting process seems to be similar to the molting process of other arthropoda.

     

Some functional properties of hemoglobin Leiden

Hemoglobin Leiden, a human mutant that contains a deletion of a glutamic residue at position 6 or 7 (A3 or A4) of the #x03B2; chains, has a slightly higher oxygen affinity in 0.1 M Phosphate, a normal Bohr effect but an abnormal response to 2,3 diphosphoglycerate and inositol hexaphosphate. Hb Leiden participates to the same extent as does Hb A in gelation with deoxy Hb S.     

Protein synthesis and the cell cycle: centrosome reproduction in sea urchin eggs is not under translational control

The reproduction, or duplication, of the centrosome is an important event in a cell's preparation for mitosis. We sought to determine if centrosome reproduction is regulated by the synthesis and accumulation of cyclin proteins and/or the synthesis of centrosome-specific proteins at each cell cycle. We continuously treat sea urchin eggs, starting before fertilization, with a combination of emetine and anisomycin, drugs that have separate targets in the protein synthetic pathway. These drugs inhibit the postfertilization incorporation of [35S]methionine into precipitable material by 97.3-100%. Autoradiography of SDS-PAGE gels of drug-treated zygotes reveals that [35S]methionine incorporates exclusively into material that does not enter the gel and material that runs at the dye front; no other labeled bands are detected. Fertilization events and syngamy are normal in drug-treated zygotes, but the cell cycle arrests before first mitosis. The sperm aster doubles once in all zygotes to yield two asters. In a variable but significant percentage of zygotes, the asters continue to double. This continued doubling is slower than normal, asynchronous between zygotes, and sometimes asynchronous within individual zygotes. High voltage electron microscopy of serial semithick sections from drug-treated zygotes reveals that 90% of the daughter centrosomes contain two centrioles of normal appearance. From these results, we conclude that centrosome reproduction in sea urchin zygotes is not controlled by the accumulation of cyclin proteins or the synthesis of centrosome-specific proteins at each cell cycle. New centrosomes are assembled from preexisting pools of ready-to-use subunits. Furthermore, our results indicate that centrosomal and nuclear events are regulated by separate pathways.     

Animal-derived antigenic variants of foot-and-mouth disease virus type A12 have low affinity for cells in culture.

We recently have shown that binding of foot-and-mouth disease virus (FMDV) to cells in culture requires an arginine-glycine-aspartic acid (RGD) sequence in the G-H loop of the capsid protein VP1 (P. W. Mason, E. Rieder, and B. Baxt, Proc. Natl. Acad. Sci. USA 91:1932-1936, 1994). In this report, we show that FMDV type A12 viruses found in infected bovine tongue tissue (BTT) differ from their tissue culture-grown derivatives at amino acid residues near the RGD. Viruses genetically engineered to contain VP1 sequences found in animal tissue (BTT viruses) were antigenically different from their tissue culture derivatives and bound to BHK cells more poorly than did the tissue culture-adapted viruses. Passage of the genetically engineered BTT viruses in BHK cells resulted in the rapid selection of variants with cell-binding properties, antigenic characteristics, and sequences typical of tissue culture-adapted viruses. These data indicate that residues near the RGD are critical for cell binding and that interpretations of antigenic variation of FMDV can be affected by virus cultivation in vitro.