Down-regulation of inhibitor of apoptosis levels provides competence for steroid-triggered cell death

A pulse of the steroid hormone ecdysone triggers the destruction of larval salivary glands during Drosophila metamorphosis through a transcriptional cascade that converges on reaper (rpr) and head involution defective (hid) induction, resulting in caspase activation and cell death. We identify the CREB binding protein (CBP) transcriptional cofactor as essential for salivary gland cell death. We show that CBP acts 1 d before the onset of metamorphosis in apparent response to a mid-third instar ecdysone pulse, when CBP is necessary and sufficient for down-regulation of the Drosophila inhibitor of apoptosis 1 (DIAP1). It is only after DIAP1 levels are reduced that salivary glands become competent to die through rpr/hid-mediated cell death. Before this time, high levels of DIAP1 block salivary gland cell death, even in the presence of ectopic rpr expression. This study shows that naturally occurring changes in inhibitor of apoptosis levels can be critical for regulating cell death during development. It also provides a molecular mechanism for the acquisition of competence in steroid signaling pathways

RNA localization in development

Cytoplasmic RNA localization is an evolutionarily ancient mechanism for producing cellular asymmetries. This review considers RNA localization in the context of animal development. Both mRNAs and non-protein-coding RNAs are localized in Drosophila, Xenopus, ascidian, zebrafish, and echinoderm oocytes and embryos, as well as in a variety of developing and differentiated polarized cells from yeast to mammals. Mechanisms used to transport and anchor RNAs in the cytoplasm include vectorial transport out of the nucleus, directed cytoplasmic transport in association with the cytoskeleton, and local entrapment at particular cytoplasmic sites. The majority of localized RNAs are targeted to particular cytoplasmic regions by cis-acting RNA elements; in mRNAs these are almost always in the 3'-untranslated region (UTR). A variety of trans-acting factors—many of them RNA-binding proteins—function in localization. Developmental functions of RNA localization have been defined in Xenopus, Drosophila, and Saccharomyces cerevisiae. In Drosophila, localized RNAs program the antero-posterior and dorso-ventral axes of the oocyte and embryo. In Xenopus, localized RNAs may function in mesoderm induction as well as in dorso-ventral axis specification. Localized RNAs also program asymmetric cell fates during Drosophila neurogenesis and yeast budding

HALLAZGO DE Echinochasmus macrocaudatus DITRICH et al. 1996 (TREMATODA: ECHINOSTOMATIDAE) EN EL CHICUACO CUELLO GRIS, Butorides striatus, EN VENEZUELA

Este estudio redescribe a Echinochasmus macrocaudatus Ditrich, Scholz y Vargas-Vásquez 1996, del intestino delgado del ave Butorides striatus de la localidad de Chirgua, estado Sucre. Venezuela. Este trabajo informa por primera vez la ocurrencia del trematodo en un hospedero natural desde que fue descrito en 1996 de los hospedros experimentales, Gallus gallus f. domestica y Anas platyrhynchos f. domestica. El trabajo provee información relacionada con su nuevo hospedero definitivo natural y la nueva distribución geográfica de este parásito.   Palabras clave: Trematoda, Echinochasmus, Aves, Butorides striatus, Distribución geográfica, Venezuela.   ABSTRACT This research redescribes Echinochasmus macrocaudatus (Ditrich, Scholz and Vargas-Vásquez 1996), found in the small intestine of a bird Butorides striatus from Chirgua, a small village in the state of Sucre, Venezuela. In this study, the presence of the trematode in a natural host is reported for the first time ever since it was described in 1996 in experimental hosts Gallus gallus f. domentica and Anas platyrhynchos f. domestica. This study provides information about the parasite´s new geographical distribution and its new natural final host.   Key words: Trematoda, Echinochasmus, Birds, Butorides striatus, Geographical distribution, Venezuela

Distribución espacial y descriptores comunitarios de ectoparásitos en branquias de cojinua, caranx ruber (bloch, 1793) de Santa Cruz, estado Sucre, Venezuela / The spatial distribution and community descriptors of ectoparasites in gills of bar jack, caranx ruber (bloch, 1793) from santa cruz, Sucre state, Venezuela

ResumenSe analizó la distribución espacial y los descriptores comunitarios (prevalencia, densidad absoluta, densidadrelativa e índice de infección) de ectoparásitos en branquias de la cojinúa carbonera, Caranx ruber Bloch, 1793recolectados en Santa Cruz, estado Sucre, Venezuela, desde mayo de 2005 hasta abril de 2006. Se determinóel índice de dispersión (ID) y el índice de Green (IG) de los ectoparásitos en 155 ejemplares de C. ruber. Seregistraron tres monogéneos (Protomicrocotyle mirabilis, Allopyragraphorus incomparabilis, Pseudomazocraessp.), dos copépodos (Lernanthrophus kroyeri, Caligus spp.) y un isópodo (Cymothoa oestrum). Los parásitosmonogéneos mostraron preferencia por el arco branquial 1 y Pseudomazocraes sp. prefirió el lado derechodel pez. Los monogéneos se consideraron especies comunes; P. mirabilis se consideró además especie centralmientras que los copépodos e isópodo resultaron especies secundarias. Los parásitos presentaron el típico patrónde distribución agregado (ID > 1; IG +). Se observó una correlación significativa entre los valores de densidadabsoluta de P. mirabilis (rs = 0,778; p < 0,05) y de Pseudomazocraes sp. (rs = 0,731; p < 0,05) con la talla de losejemplares del hospedero, C. ruber. Las comunidades de monogeneos presentaron fluctuaciones estacionales. Elmayor número de especies de parásitos en un hospedero determinado, estuvo relacionado con el medio ambientemás diverso de la localidad.Palabras clave: Microhábitat, peces marinos, ectoparásito, Monogenea, Isopoda, Copepoda.ABSTRACTThe spatial distribution and community descriptors (prevalence, absolute density, relative density andinfection index) of the ectoparasites in gills of the bar jack Caranx ruber Bloch, 1793 from Santa Cruz, Sucrestate, Venezuela, were evaluated from May 2005 to April 2006. The Dispersion Index (DI), and Green Index (GI)of ecoparasites from 155 specimens of C. rubber is described. There were three monogeneans (Protomicrocotylemirabilis, Allopyragraphorus incomparabilis, Pseudomazocraes s p.), t wo c opepods (Lernanthrophus kroyeri,Caligus spp.), and one isopod (Cymothoa oestrum). The monogenean parasites showed preference for gill arch Iand Pseudomazocraes sp. preferred the right side of the fish. The monogeneans were considered common specieswhile P. mirabilis was also considered a central species, and the copepods and isopod were considered as secondaryspecies. The parasites showed a typical aggregate pattern of distribution (ID > 1; IG +). There was a significantcorrelation between the values of absolute density of P. mirabilis (rs = 0.778, p < 0.05) and Pseudomazocraes sp.(rs = 0.731, p <0.05) with the size of the host, C. ruber. The parasite communities showed seasonal fluctuation.The highest number of parasite species in a given host was related to the higher diversity of the local environment.Key words: Microhabitat, marine fish, ectoparasite, Monogenea, Copepoda, Isopoda

Ultra-thin biocompatible implantable chip for bidirectional communication with peripheral nerves

To realize optimal recording and stimulation of peripheral nerve cells, a CMOS chip is made with a multitude of electrodes which can be individually addressed in order to select after implantation the 16 best positioned electrodes. Since the Foreign Body Reaction should be minimal for optimum electrode-nerve contact, the CMOS chip is thinned down to 35um and fully packaged resulting in a 75um thin encapsulated chip. The chip is embedded in a biocompatible stack consisting of polymers and inorganic diffusion barriers deposited using atomic layer deposition (ALD). A biocompatible metallization is realized using gold and platinum sandwiched between polymers and ALD layers for flexible interconnects, and iridium oxide (IrOx) is selected as electrode material for optimal charge injection during stimulation. After this dedicated packaging based on the FITEP technology platform (Flexible Implantable Thin Electronic Package), the CMOS chip is still fully functional, which was tested dry (in air) as well as during submersion in saline. The form factor of the packaged chip is optimized for intra-fascicular implantation with minimum tissue damage. First acute in vivo stimulation tests proved that the stimulation capabilities of the IrOx electrodes are very good

A Reversible Low Frequency Alternating Current Nerve Conduction Block Applied to Mammalian Autonomic Nerves

Electrical stimulation can be used to modulate activity within the nervous system in one of two modes: (1) Activation, where activity is added to the neural signalling pathways, or (2) Block, where activity in the nerve is reduced or eliminated. In principle, electrical nerve conduction block has many attractive properties compared to pharmaceutical or surgical interventions. These include reversibility, localization, and tunability for nerve caliber and type. However, methods to effect electrical nerve block are relatively new. Some methods can have associated drawbacks, such as the need for large currents, the production of irreversible chemical byproducts, and onset responses. These can lead to irreversible nerve damage or undesirable neural responses. In the present study we describe a novel low frequency alternating current blocking waveform (LFACb) and measure its efficacy to reversibly block the bradycardic effect elicited by vagal stimulation in anaesthetised rat model. The waveform is a sinusoidal, zero mean(charge balanced), current waveform presented at 1 Hz to bipolar electrodes. Standard pulse stimulation was delivered through Pt-Black coated PtIr bipolar hook electrodes to evoke bradycardia. The conditioning LFAC waveform was presented either through a set of CorTec® bipolar cuff electrodes with Amplicoat® coated Pt contacts, or a second set of Pt Black coated PtIr hook electrodes. The conditioning electrodes were placed caudal to the pulse stimulation hook electrodes. Block of bradycardic effect was assessed by quantifying changes in heart rate during the stimulation stages of LFAC alone, LFAC-and-vagal, and vagal alone. The LFAC achieved 86.2±11.1% and 84.3±4.6% block using hook (N = 7) and cuff (N = 5) electrodes, respectively, at current levels less than 110 µAp (current to peak). The potential across the LFAC delivering electrodes were continuously monitored to verify that the blocking effect was immediately reversed upon discontinuing the LFAC. Thus, LFACb produced a high degree of nerve block at current levels comparable to pulse stimulation amplitudes to activate nerves, resulting in a measurable functional change of a biomarker in the mammalian nervous system

In-vivo application of low frequency alternating currents on porcine cervical vagus nerve evokes reversible nerve conduction block

Background: This paper describes a method to reversibly block nerve conduction through direct application of a 1 Hz sinusoidal current waveform delivered through a bipolar nerve cuff electrode. This low frequency alternating current (LFAC) waveform was previously shown to reversibly block the effects of vagal pulse stimulation evoked bradycardia in-vivo in the anaesthetised rat model (Mintch et al. 2019). The present work measured the effectiveness of LFAC block on larger caliber myelinated vagal afferent fibers in human sized nerve bundles projecting to changes in breathing rate mediated by the Hering-Breuer (HB) reflex in anaesthetized domestic swine (n=5). Methods: Two bipolar cuff electrodes were implanted unilaterally to the left cervical vagus nerve, which was crushed caudal to the electrodes to eliminate cardiac effects. A tripolar recording cuff electrode was placed rostral to the bipolar stimulating electrodes on the same nerve to measure changes in the compound nerve action potentials (CNAP) elicited by the vagal pulse stimulation and conditioned by the LFAC waveform. Standard pulse stimulation was applied at a sufficient level to induce a reduction in breathing rate through the HB reflex. If unblocked, the HB reflex would cause breathing to slow down and potentially halt completely. Block was quantified by the ability of LFAC to reduce the effect of the HB reflex by monitoring the respiration rate during LFAC alone, LFAC and vagal stimulation, and vagal stimulation alone. Results: LFAC achieved 87.2 ±8.8% block (n=5) at current levels of 1.1 ±0.3 mAp (current to peak), which was well within the water window of the working electrode. CNAP showed changes that directly correlated to the effectiveness of LFAC block, which manifested itself as the slowing and amplitude reduction of components of the CNAP. Conclusion: These novel findings suggest that LFAC is a potential alternative or complementary method to other electrical blocking techniques in clinical applications

Drosophila Squid/hnRNP helps Dynein switch from a gurken mRNA transport motor to an ultrastructural static anchor in sponge bodies

In Drosophila oocytes, dorso-anterior transport of gurken mRNA requires both the Dynein motor and the heterogeneous nuclear ribonucleoprotein (hnRNP) Squid. We show that gurken transcripts are transported directly on microtubules by Dynein in nonmembranous electron-dense transport particles that also contain Squid and the transport cofactors Egalitarian and Bicaudal-D. At its destination, gurken mRNA is statically anchored by Dynein within large electron-dense cytoplasmic structures known as sponge bodies. Egalitarian and Bicaudal-D contribute only to active transport, whereas Dynein and Squid are also required for gurken mRNA anchoring and the integrity of sponge bodies. Disrupting Dynein function disperses gurken mRNA homogeneously throughout the cytoplasm, whereas the loss of Squid function converts the sponge bodies into active transport particles. We propose that Dynein acts as a static structural component for the assembly of gurken mRNA transport and anchoring complexes, and that Squid is required for the dynamic conversion of transport particles to sponge bodies