Dysferlin is essential for endocytosis in the sea star oocyte

Dysferlin is a calcium-binding transmembrane protein involved in membrane fusion and membrane repair. In humans, mutations in the dysferlin gene are associated with muscular dystrophy. In this study, we isolated plasma membrane-enriched fractions from full-grown immature oocytes of the sea star, and identified dysferlin by mass spectrometry analysis. The full-length dysferlin sequence is highly conserved between human and the sea star. We learned that in the sea star Patiria miniata, dysferlin RNA and protein are expressed from oogenesis to gastrulation. Interestingly, the protein is highly enriched in the plasma membrane of oocytes. Injection of a morpholino against dysferlin leads to a decrease of endocytosis in oocytes, and to a developmental arrest during gastrulation. These results suggest that dysferlin is critical for normal endocytosis during oogenesis and for embryogenesis in the sea star and that this animal may be a useful model for studying the relationship of dysferlin structure as it relates to its function.     

Gastrulation in the sea urchin embryo requires the deposition of crosslinked collagen within the extracellular matrix

This study demonstrates that a collagenous extracellular matrix (ECM) is necessary for gastrulation in the sea urchin embryo. The approach taken was to disrupt collagen processing with two types of agents (a lathyritic agent, beta-aminopropionitrile (BAPN), and three types of proline analogs: dehydroproline, cis-OH-proline, and azetidine carboxylic acid) and to assess the effect on embryogenesis by morphological, immunological, and biochemical criteria. Embryos chronically exposed to either of the agents following fertilization displayed no detectable developmental abnormalities before the mesenchyme blastula stage. These embryos, however, did not gastrulate nor differentiate any further and remained at the mesenchyme blastula stage for at least 36 hr. Upon removal of the agents, the embryos resumed a normal developmental schedule and formed pluteus larvae that were indistinguishable from control embryos. By immunofluorescence studies with monospecific antibodies to type I and type IV collagens it is seen that the lathyritic agent BAPN reduces the accumulation of collagens within the ECM. This effect is confirmed and quantitated by use of an ELISA and by a biochemical determination of OH-proline. When the agents are removed from the inhibited embryos, collagen deposition returns to normal, coincident with gastrulation. Western-blot analysis, using monospecific antibodies to collagen, demonstrates that the effect of the lathyritic agent is to reduce the stability of the extracellular collagen by inhibiting the intra- and intermolecular crosslinking of collagen molecules. BAPN exhibits a dose-dependent effect on morphogenesis, but has no effect on respiration nor on protein synthesis of the embryos throughout development. Although the lathyritic agent affects collagen deposition, it is shown to not affect the expression of other molecules of the ECM, nor that of several cell surface molecules. However, a cell surface molecule that is expressed specifically in the endoderm, termed Endo 1, is not expressed in the inhibited embryos. Endo 1 is expressed after removal of the lathyritic agent and its appearance is coincident with gastrulation in the recovered embryos. These results suggest that a collagenous ECM is important for gastrulation and subsequent differentiation in the sea urchin, but not for earlier developmental processes. In addition, the dependence of Endo 1 expression on the collagenous ECM raises the possibility that this cell surface molecule is in some way regulated by interactions of the presumptive endodermal cells with the ECM.     

Changes in the Intestinal Microbiota of Wild Atlantic cod Gadus morhua L. Upon Captive Rearing

The commensal microbiota plays an important role in the well-being of the host organism, and it would be worthwhile to know the tenacious communities among them. Therefore, a study was undertaken to examine the changes in constitution of the intestinal microbiota of wild fish consequential to captivity. At first, the composition of intestinal microorganisms of Atlantic cod caught from the coastal area off Bod?, Norway, was examined. Thereafter, the changes in the bacterial community of the captive fish after offering them artificial feed or subjecting them to starvation were studied. The microbiota from the intestinal contents and wall segments were analyzed quantitatively by spread plate technique and DAPI staining and qualitatively by denaturing gradient gel electrophoresis. The study revealed that the counts of intestinal microbes in wild-caught Atlantic cod were not affected by captive rearing for 6?weeks, either when fed or when starved. However, the diversity of intestinal bacterial community was reduced in response to artificial feeding, whereas the change was restricted upon starvation.     

Molecular modelling and simulations in cancer research

The complexity of cancer and the vast amount of experimental data available have made computer-aided approaches necessary. Biomolecular modelling techniques are becoming increasingly easier to use, whereas hardware and software are becoming better and cheaper. Cross-talk between theoretical and experimental scientists dealing with cancer-research from a molecular approach, however, is still uncommon. This is in contrast to other fields, such as amyloid-related diseases, where molecular modelling studies are widely acknowledged. The aim of this review paper is therefore to expose some of the more common approaches in molecular modelling to cancer scientists in simple terms, illustrating success stories while also revealing the limitations of computational studies at the molecular level.