MARCH6 and TRC8 facilitate the quality control of cytosolic and tail‐anchored proteins

Misfolded or damaged proteins are typically targeted for destruction by proteasome‐mediated degradation, but the mammalian ubiquitin machinery involved is incompletely understood. Here, using forward genetic screens in human cells, we find that the proteasome‐mediated degradation of the soluble misfolded reporter, mCherry‐CL1, involves two ER‐resident E3 ligases, MARCH6 and TRC8. mCherry‐CL1 degradation is routed via the ER membrane and dependent on the hydrophobicity of the substrate, with complete stabilisation only observed in double knockout MARCH6/TRC8 cells. To identify a more physiological correlate, we used quantitative mass spectrometry and found that TRC8 and MARCH6 depletion altered the turnover of the tail‐anchored protein heme oxygenase‐1 (HO‐1). These E3 ligases associate with the intramembrane cleaving signal peptide peptidase (SPP) and facilitate the degradation of HO‐1 following intramembrane proteolysis. Our results highlight how ER‐resident ligases may target the same substrates, but work independently of each other, to optimise the protein quality control of selected soluble and tail‐anchored proteins.     

RAD marker microarrays enable rapid mapping of zebrafish mutations

We constructed a restriction site associated DNA (RAD) marker microarray to facilitate rapid genetic mapping of zebrafish mutations. Using these microarrays with a bulk segregant approach, we localized previously unmapped mutations to genomic regions just a few centiMorgans in length. Furthermore, we developed an approach to assay individual RAD markers in pooled populations and refined one region. The RAD approach is highly effective for genetic mapping in zebrafish and is an attractive option for mapping in other organisms.     

OntologyWidget – a reusable,embeddable widget for easily locating ontology terms

Background  

Biomedical ontologies are being widely used to annotate biological data in a computer-accessible, consistent and well-defined manner. However, due to their size and complexity, annotating data with appropriate terms from an ontology is often challenging for experts and non-experts alike, because there exist few tools that allow one to quickly find relevant ontology terms to easily populate a web form.     

The zebrafish genome in context: ohnologs gone missing

Some zebrafish genes appear to lack an ortholog in the human genome and researchers often call them "novel" genes. The origin of many so-called "novel" genes becomes apparent when considered in the context of genome duplication events that occurred during evolution of the phylum Chordata, including two rounds at about the origin of the subphylum Vertebrata (R1 and R2) and one round before the teleost radiation (R3). Ohnologs are paralogs stemming from such genome duplication events, and some zebrafish genes said to be "novel" are more appropriately interpreted as "ohnologs gone missing", cases in which ohnologs are preserved differentially in different evolutionary lineages. Here we consider ohnologs present in the zebrafish genome but absent from the human genome. Reasonable hypotheses are that lineage-specific loss of ohnologs can play a role in establishing lineage divergence and in the origin of developmental innovations. How does the evolution of ohnologs differ from the evolution of gene duplicates arising from other mechanisms, such as tandem duplication or retrotransposition? To what extent do different major vertebrate lineages or different teleost lineages differ in ohnolog content? What roles do differences in ohnolog content play in the origin of developmental mechanisms that differ among lineages? This review explores these questions.     

Molecular docking analysis of glycogen phosphorylase with inhibitors from Cissampelos pareira Linn.

Cissampelos pareira Linn. is a climbing herb known in Indian traditional medicine as laghupatha. It belongs to the Menispermaceae family. The enzyme glycogen phosphorylase (GP) is a promising target for the treatment of type-2 diabetes (T2DM). A variety of natural product inhibitors with both pharmaceutical and nutraceutical potential have been reported in the search for powerful, selective and drug-like GP inhibitors that could lead to hypoglycemic medicines. Therefore, it is of interest to document the molecular docking analysis data of glycogen phosphorylase with compounds from Cissampelos pareira Linn. We report the optimal binding features of 4 compounds namely Trans-N-feruloyltyramine, Coclaurine, Magnoflorine, and Curine with the target protein for further consideration in the context of T2DM.     

EFFECT OF 2-CHLOROETHYLTRIMETHYLAMMONIUM CHLORIDE ON FERN GAMETOPHYTES

Kelley , A. G., and S. N. Postlethwait . (Purdue U., Lafayette, Ind.) Effect of 2-chloroethyltrimethylammonium chloride on fern gametophytes. Amer. Jour. Bot. 49(7): 778–786. Illus. 1962.—2-chloroethyltrimethylammonium chloride (CCC) promotes growth of fern gametophytes by stimulating the rate of cell division. The transition from filamentous to biplanar to triplanar cell division is hastened, resulting in earlier and more numerous gametangia on treated prothalli. Growth is stimulated in the range of 10^-4 m –10^-2 m CCC, with the optimal effect at 10^-3 m CCC. The time sequence of rhizoid production is altered by 10^-2 m CCC; the resultant production of rhizoids by prothalli treated with 10^-2 m CCC does not exceed that of controls.     

Development of gap junctions in normal and mutant ovaries of Drosophila melanogaster

An ovarian follicle of Drosophila consists of an oocyte, 15 nurse cells, and hundreds of follicular epithelial cells. A freeze-fracture analysis of the surfaces between glutaraldehyde-fixed ovarian cells showed that all three cell types were interconnected by gap junctions. This is the first report of gap junctions between adjacent nurse cells, between nurse cells and oocytes, and between follicle cells and oocytes in Drosophila. Since we did not observe intramembranous particle clumping into crystalline patterns and since structurally different gap junctions occurred at different times in development and at different cell-cell interfaces, it is unlikely that fixation artifacts influenced particle distribution in our experiments. A computer-assisted morphometric analysis showed that the extent, size, and morphology of gap junctions varied with development and that these junctions can cover up to 9% of the cell surfaces. To test the role of gap junctions in follicular maturation, we studied ovaries from flies homozygous for the female sterile mutation fs(2)A17, in which follicles develop normally until yolk deposition commences. During the development of mutant follicles, gap junctions became abnormal before any other morphological aspect of the follicle. These studies show that gap junctions are available to play an important role in coordinating intercellular activities between all three cell types in ovarian follicles of Drosophila.