The Amsterdam Declaration on Fungal Nomenclature was agreed at an international symposium convened in Amsterdam on 19–20 April 2011 under the auspices of the International Commission on the Taxonomy of Fungi (ICTF). The purpose of the symposium was to address the issue of whether or how the current system of naming pleomorphic fungi should be maintained or changed now that molecular data are routinely available. The issue is urgent as mycologists currently follow different practices, and no consensus was achieved by a Special Committee appointed in 2005 by the International Botanical Congress to advise on the problem. The Declaration recognizes the need for an orderly transitition to a single-name nomenclatural system for all fungi, and to provide mechanisms to protect names that otherwise then become endangered. That is, meaning that priority should be given to the first described name, except where that is a younger name in general use when the first author to select a name of a pleomorphic monophyletic genus is to be followed, and suggests controversial cases are referred to a body, such as the ICTF, which will report to the Committee for Fungi. If appropriate, the ICTF could be mandated to promote the implementation of the Declaration. In addition, but not forming part of the Declaration, are reports of discussions held during the symposium on the governance of the nomenclature of fungi, and the naming of fungi known only from an environmental nucleic acid sequence in particular. Possible amendments to the Draft BioCode (2011) to allow for the needs of mycologists are suggested for further consideration, and a possible example of how a fungus only known from the environment might be described is presented.

In renal collecting ducts, vasopressin increases the expression of and redistributes aquaporin-2 (AQP2) water channels from intracellular vesicles to the apical membrane, leading to urine concentration. However, basolateral membrane expression of AQP2, in addition to AQP3 and AQP4, is often detected in inner medullary principal cells in vivo. Here, potential mechanisms that regulate apical versus basolateral targeting of AQP2 were examined. The lack of AQP2-4 association into heterotetramers and the complete apical expression of AQP2 when highly expressed in Madin-Darby canine kidney cells indicated that neither heterotetramerization of AQP2 with AQP3 and/or AQP4, nor high expression levels of AQP2 explained the basolateral AQP2 localization. However, long term hypertonicity, a feature of the inner medullary interstitium, resulted in an insertion of AQP2 into the basolateral membrane of Madin-Darby canine kidney cells after acute forskolin stimulation. Similarly, a marked insertion of AQP2 into the basolateral membrane of principal cells was observed in the distal inner medulla from normal rats and Brattleboro rats after acute vasopressin treatment of tissue slices that had been chronically treated with vasopressin to increase interstitial osmolality in the medulla, but not in tissues from vasopressin-deficient Brattleboro rats. These data reveal for the first time that chronic hypertonicity can program cells in vitro and in vivo to change the insertion of a protein into the basolateral membrane instead of the apical membrane.The renal collecting duct is involved in urine concentration via a process that is regulated by the antidiuretic hormone arginine vasopressin (AVP).1 After binding to its receptor on target cells in the kidney collecting duct, AVP initiates an intracellular signaling cascade that increases cytosolic cAMP and calcium levels (1-3). Upon activation of protein kinase A, aquaporin-2 (AQP2) is phosphorylated and is rapidly redistributed from intracellular vesicles to the apical membrane of collecting duct principal cells. Driven by an osmotic gradient, water then moves into the cell apically via AQP2, and exits across the basolateral membrane via AQP3 and/or AQP4 (4, 5). In addition to this short term effect, increased circulating AVP levels also lead to an increased expression of AQP2 protein, which is mediated via a cAMP responsive element in the AQP2 gene promoter (6 -8). Additionally, the expression of AQP3 is increased, but the level of AQP4 remains unchanged (9, 10). Although the majority of AQP2 is located in the apical plasma membrane under "steady-state" conditions in normally hydrated animals, immunocytochemical studies have shown that AQP2 antigenicity can also be detected in the basolateral plasma membrane of collecting duct principal cells in these rats. This basolateral staining pattern becomes more prominent with increased AVP levels or water deprivation in rats, and is especially prominent in the principal cells of the inner medulla (11).The factors and mechanisms that determine t...

Renal regulation of mammalian water homeostasis is mediated by the aquaporin-1 (AQP1) water channel, which is expressed in the apical and basolateral membranes of proximal tubules and descending limbs of Henle, and aquaporin-2 (AQP2), which is redistributed from intracellular vesicles to the apical membrane (AM) of collecting duct cells with vasopressin. In transfected Madin-Darby canine kidney cells, AQP1 and AQP2 are regulated similarly, which indicates that routing elements reside in their primary sequences. We studied the role of the AQP2 COOH terminus in apical routing and AQP2 shuttling. An AQP1 chimera (AQP1 with an AQP2 tail: AQP1/2-N220) was located only in the AM independent of forskolin treatment. Forskolin increased the apical expression of AQP1 and AQP1/2-N220 less than twofold; that of AQP2 increased more than fourfold with concomitant changes in osmotic water permeabilities. The dimeric AQP2 tail coupled to placental alkaline phosphatase (AQP2-Plap) was retained in intracellular vesicles different from those of homotetrameric wild-type AQP2; the same protein without the AQP2 tail (TMR-Plap) was only expressed in the AM. The study shows that the AQP2 COOH tail is necessary but not sufficient for routing to the AM and suggests that other parts of AQP2 are needed for AQP2 accumulation in intracellular vesicles.

Transport through the endocytic pathway is inhibited during mitosis. The mechanism responsible for this inhibition is not understood. Rab4 might be one of the proteins involved as it regulates transport through early endosomes, is phosphorylated by p34(cdc2) kinase, and is translocated from early endosomes to the cytoplasm during mitosis. We investigated the perturbation of the rab4 GTPase cycle during mitosis. Newly synthesized rab4 was less efficiently targeted to membranes during mitosis. By subcellular fractionation of mitotic cells, we found a large increase of cytosolic rab4 in the active GTP-form, an increase not associated with the cytosolic rabGDP chaperone GDI. Instead, phosphorylated rab4 is in a complex with the peptidyl-prolyl isomerase Pin1 during mitosis, but not during interphase. Our results show that less efficient recruitment of rab4 to membranes and a bypass of the normal GDI-mediated retrieval of rab4GDP from early endosomes reduce the amount of rab4GTP on membranes during mitosis. We propose that phosphorylation of rab4 inhibits both the recruitment of rab4 effector proteins to early endosomes and the docking of rab4-containing transport vesicles. This mechanism might contribute to the inhibition of endocytic membrane transport during mitosis.

The small GTPase rab4a is associated with early endocytic compartments and regulates receptor recycling from early endosomes. To understand how rab4a mediates its function, we searched for proteins which associate with this GTPase and regulate its activity in endocytic transport. Here we identified rabaptin4, a novel effector molecule of rab4a. Rabaptin4 is homologous with rabaptin5 and contains a C-terminal deletion with respect to rabaptin5. Rabaptin4 preferentially interacts with rab4a-GTP and to a lesser extent with rab5aGTP. We identified a rab4a-binding domain in the N-terminal region of rabaptin4, and two binding sites for rab5, including a novel N-terminal rab5a-binding site. Rabaptin4 is a cytosolic protein that inhibits the intrinsic GTP hydrolysis rate of rab4a and is recruited by rab4a-GTP to recycling endosomes enriched in cellubrevin and internalized indocarbocyanine-3 (Cy3)-labelled transferrin. We propose that rabaptin4 assists in the docking of transport vesicles en route from early endosomes to recycling endosomes.