Cloning and developmental expression of a novel, secreted frizzled-related protein from the sea urchin, Strongylocentrotus purpuratus

Wnt proteins and their receptors, members of the frizzled protein family, play a key role in regulating a wide range of developmental processes. Recently, putative regulators of Wnt signaling known as secreted frizzled-related proteins (SFRPs) have been identified in several vertebrates. Here, we describe the cloning of a novel SFRP (suSFRP1) from the sea urchin, Strongylocentrotus purpuratus. SuSFRP1 contains a putative signal sequence, four cysteine-rich domains and a single Ig domain. The developmental expression of suSFRP1 mRNA is highly dynamic and can be separated into three phases: (1) abrupt accumulation in most or all cells of the embryo at the early blastula stage; (2) restriction of expression to the prospective endoderm and animal pole region of the gastrula; and (3) expression in prospective muscle cells of the coelomic pouches during late embryogenesis.     

Identification and developmental expression of new biomineralization proteins in the sea urchin Strongylocentrotus purpuratus

The endoskeleton of the sea urchin larva is a network of calcareous rods secreted by primary mesenchyme cells (PMCs). In this study, we identified seven new biomineralization-related proteins through an analysis of a large database of gene products expressed by PMCs. The proteins include three new spicule matrix proteins (SpSM29, SpSM32, and SpC-lectin), two proteins related to the PMC-specific cell surface glycoprotein MSP130 (MSP130-related-1 and -2), and two novel proteins (SpP16 and SpP19). The genes encoding these proteins are expressed specifically by cells of the large micromere-PMC lineage and are activated zygotically beginning at the blastula stage, prior to PMC ingression. Several of the mRNAs show regulated patterns of expression within the PMC syncytium that correlate with the pattern of skeletal rod growth. This work identifies new proteins that may regulate the process of biomineralization in this tractable model system.     

Overexpression of lysosomal acid lipase and other proteins in atherosclerosis

Atherosclerosis is one of the major causes of morbidity and mortality in the western world. The existing data of elevated expression levels of proteins like DNA damage and DNA repair enzymes in human atherosclerotic plaques are reviewed. From the literature, the effect of overexpression of different proteins using adenoviral vectors or the model of transgenic mice on the development of atherosclerosis will be discussed. Special focus is placed on the lysosomal acid lipase (LAL), because LAL connects extra-cellular with intra-cellular lipid metabolism and is the only hydrolase for cleavage of cholesteryl esters delivered to the lysosomes. Patients with a deficiency of LAL show an accumulation of lipids in the cells and develop pre-mature atherosclerosis. To answer the question of the influence of LAL in atherosclerosis if overexpressed, we show for the first time data of transgenic mice overexpressing LAL and the effect on the lipid level.     

Differential stability of beta-catenin along the animal-vegetal axis of the sea urchin embryo mediated by dishevelled

beta-Catenin has a central role in the early axial patterning of metazoan embryos. In the sea urchin, beta-catenin accumulates in the nuclei of vegetal blastomeres and controls endomesoderm specification. Here, we use in-vivo measurements of the half-life of fluorescently tagged beta-catenin in specific blastomeres to demonstrate a gradient in beta-catenin stability along the animal-vegetal axis during early cleavage. This gradient is dependent on GSK3beta-mediated phosphorylation of beta-catenin. Calculations show that the difference in beta-catenin half-life at the animal and vegetal poles of the early embryo is sufficient to produce a difference of more than 100-fold in levels of the protein in less than 2 hours. We show that dishevelled (Dsh), a key signaling protein, is required for the stabilization of beta-catenin in vegetal cells and provide evidence that Dsh undergoes a local activation in the vegetal region of the embryo. Finally, we report that GFP-tagged Dsh is targeted specifically to the vegetal cortex of the fertilized egg. During cleavage, Dsh-GFP is partitioned predominantly into vegetal blastomeres. An extensive mutational analysis of Dsh identifies several regions of the protein that are required for vegetal cortical targeting, including a phospholipid-binding motif near the N-terminus.     

Annual and seasonal variation of individual weights of adult water insects

Annual and seasonal variations of individual weights of dominant species of aquatic insects in Breitenbach, Germany, are described and the probable reasons of variations are discussed. Variations are not correlated in different species, and there appears to be no uniform explanation of the phenomenon.     

Arthropoda of the subantarctic islands of New Zealand

Six gripopterygid stonefly species are found on New Zealand's subantarctic islands. They belong to the genera Apteryoperla and Aucklandobius, which are endemic to New Zealand and those islands. The only winged species, Aucklandobius complementarius Enderlein, is found on the Auckland Islands with A. gressitti n.sp., Apteryoperla turbotti lilies, and A. kuscheli n.sp. Campbell Island is inhabited by Apteryoperla campbelli lilies and A. longicauda lilies; there is also a doubtful record of Aucklandobius complementarius. All Apteryoperla species except longicauda have terrestrial larvae.     

Diphosphoinositol pentakisphosphate as a novel mediator of insulin exocytosis

The pancreatic β-cell has served as an important model system for the revelation of new physiological roles for inositides. Initially, our studies were restricted to the role of inositol 1,4,5-trisphosphate (Ins(1,4,5)P₃) in the regulation of cytoplasmic free calcium concentration ([Ca²⁺]_i), but it soon became clear that other inositol phosphates could also regulate β-cell [Ca²⁺]_i. For example, inositol hexakisphosphate (InsP₆) promotes the opening of the key voltage-dependent L-type Ca²⁺ channels, responsible for Ca²⁺ influx and the final release of insulin. Furthermore, InsP₆ and inositol lipids such as phosphatidylinositol 4,5-bisphosphate are intimately involved the regulation of endocytosis and exocytosis. We now review our most recent work, which has focused on the phosphorylation product of InsP₆, diphosphoinositol pentakisphosphate (PP-InsP₅ or InsP₇). We have established that InsP₇ via the activity of the InsP₆ kinase, IP6K1, promotes insulin release from the readily releasable pool of vesicles (RRP). The RRP is thought to be synonymous with the first phase of insulin secretion. This has a direct implication for type 2 diabetes, as it is this initial phase of insulin release that is curtailed in the disease. Hints from human genetic linkage studies suggest that disruption of IP6K1 could be a factor in the development of type 2 diabetes and a recent mouse model, where IP6K1 is universally deleted, exhibits lowered plasma insulin levels. Hence, this is yet another important example demonstrating how the β-cell utilizes inositides in the regulation of function. Although we do not fully understand the underlying molecular mechanisms, it is clear that IP6K1-mediated production of InsP₇ has an essential role in the regulation of the insulin secretory process.