Parasites component community in wild population of Pterophyllum scalare Schultze, 1823 and Mesonauta acora Castelnau, 1855, cichlids from the Brazilian Amazon

The aim of the present study was to compare the component parasite communities of the Pterophyllum scalare and Mesonauta acora cichlids in the Amazon River system in northern Brazil. From September to December 2012, 42 specimens of P. scalare and 38 specimens of M. acora were captured using hand nets and gillnets in the Igarapé Fortaleza basin, a tributary of the Amazon River in the state of Amapá. Of the P. scalare specimens examined, 97.6% were parasitized by Ichthyophthirius multifiliis, Tripartiella sp., Trichodina nobilis, Gussevia spiralocirra, Posthodiplostomum sp., Capillaria pterophylli, Ichthyouris sp. and Gorytocephalus spectabilis. Similarly, all specimens of M. acora were parasitized by I. multifiliis, Tripartiella sp, T. nobilis, Sciadicleithrum joanae, Posthodiplostomum sp., Pseudoproleptus sp., Ichthyouris sp. and G. spectabilis. However, for both hosts the dominance was of I. multifiliis and with an overdispersion of parasites. Parasite communities of P. scalare and M. acora were similar and only Pseudoproleptus sp. and Posthodiplostomum sp. were larvae. Brillouin diversity, parasite species richness and evenness were higher for M. acora than for P. scalare, which presented a negative correlation of parasite abundance with body size. Both cichlid species had parasite communities characterized by low diversity and low species richness, with a predominance of ectoparasite species and greatest richness of helminth species, with a low abundance of endoparasites. This was the first study on the parasite diversity in wild P. scalare and M. acora.     

Albinism in plants – far beyond the loss of chlorophyll: Structural and physiological aspects of wild‐type and albino royal poinciana (Delonix regia) seedlings

• The partial or complete loss of chlorophylls, or albinism, is a rare phenomenon in plants. In the present study, we provide the first report of the occurrence in albino Delonix regia seedlings and describe the morpho‐physiological changes associated with albinism.
• Wild‐type (WT) and albino seedlings were characterized. Leaflets samples were processed following common procedures for analysis with light, scanning and transmission electron microscopy. The chlorophyll a fluorescence parameters and the carbohydrate, lipid and soluble protein content were also determined in leaf and cotyledon samples of both albino and WT seedlings.
• Albino seedlings showed reduced growth. They also had lower chlorophyll and protein content in foliar tissues than WT seedlings, in addition to lower concentrations of lipids and carbohydrates stored in cotyledons. The chloroplasts of albino seedlings were poorly developed, with an undefined internal membrane system and the presence of plastoglobules. Wild‐type seedlings had a uniseriate and hypoestomatic epidermis. The mesophyll was dorsiventral, consisting of a layer of palisade parenchyma and two to four layers of spongy parenchyma. In albino seedlings, the spongy parenchyma was compact, with few intercellular spaces, and the thickness of the mesophyll was larger, resulting in increased thickness of the leaf blade. Albino seedlings had higher stomatal density and number of pavement cells, although the stomata had smaller dimensions.
• In addition to the partial loss of chlorophylls, albino D. regia showed changes at physiological and structural levels, demonstrating the crucial nature of photosynthetic pigments during the development and differentiation of plant leaf tissues/cells.

     

Regulation of mitochondrial fission by GIPC-mediated Drp1 retrograde transport

Dynamin-related protein 1 (Drp1) is a key regulator of mitochondrial fission, a large cytoplasmic GTPase recruited to the mitochondrial surface via transmembrane adaptors to initiate scission. While Brownian motion likely accounts for the local interactions between Drp1 and the mitochondrial adaptors, how this essential enzyme is targeted from more distal regions like the cell periphery remains unknown. Based on proteomic interactome screening and cell-based studies, we report that GAIP/RGS19-interacting protein (GIPC) mediates the actin-based retrograde transport of Drp1 toward the perinuclear mitochondria to enhance fission. Drp1 interacts with GIPC through its atypical C-terminal PDZ-binding motif. Loss of this interaction abrogates Drp1 retrograde transport resulting in cytoplasmic mislocalization and reduced fission despite retaining normal intrinsic GTPase activity. Functionally, we demonstrate that GIPC potentiates the Drp1-driven proliferative and migratory capacity in cancer cells. Together, these findings establish a direct molecular link between altered GIPC expression and Drp1 function in cancer progression and metabolic disorders.     

Diacylglycerol kinase inhibition prevents IL-2-induced G1 to S transition through a phosphatidylinositol-3 kinase-independent mechanism.

Stimulation via IL-2R ligation causes T lymphocytes to transit through the cell cycle. Previous experiments by our group have demonstrated that, in human T cells, IL-2 binding induces phosphatidic acid production through activation of the alpha isoform of diacylglycerol kinase. In this study, using the IL-2-dependent mouse T cell line CTLL-2, we demonstrate that pharmacological inhibition of IL-2-induced diacylglycerol kinase activation is found to block IL-2-induced late G1 to S transition without affecting cell viability. Herein, we demonstrate that diacylglycerol kinase inhibition has a profound effect on the induction of the protooncogenes c-myc, c-fos, and c-raf by IL-2, whereas expression of bcl-2 and bcl-xL are not affected. When the IL-2-regulated cell cycle control checkpoints are examined in detail, we demonstrate that inhibition of diacylglycerol kinase activation prevents IL-2 induction of cyclin D3 without affecting p27 down-regulation. The strict control of cell proliferation exerted by phosphatidic acid through activation of diacylglycerol kinase is independent of other well-characterized IL-2R-derived signals, such as the phosphatidylinositol-3 kinase/Akt pathway, indicating the existence of a different and important mechanism to control cell division.