Hybanthopsis, a new genus of Violaceae from Eastern Brazil

A new genus of Violaceae is described from Brazil.Hybanthopsis Paula-Souza, with a single species (H. bahiensis Paula-Souza), is endemic to caatingas of Bahia, Brazil, and is morphologically most similar toHybanthus, from which it differs by the fruit morphology and especially its peculiar seeds.

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Um novo gênero brasileiro de Violaceae é descrito.Hybanthopsis Paula-Souza, com uma única espécie (H. bahiensis Paula-Souza), é endêmico de caatingas do Estado da Bahia, e é morfologicamente mais similar aHybanthus, do qual difere pela morfologia do fruto e especialmente por suas sementes peculiares.

     

Effect of Campsurus notatus on NH+4, DOC Fluxes,O2 Uptake and Bacterioplankton Production in Experimental Microcosms with Sediment‐Water Interface of an Amazonian Lake Impacted by Bauxite Tailings

The aim of this study was to evaluate the influence of Campusurus notatus Eaton 1868 (Ephemeroptera: Polimitarciydae) and the impact of bauxite tailings on ammonium (NH₄⁺) and dissolved organic carbon (DOC) fluxes, oxygen uptake and bacterioplankton production in the sediment‐water interface of Lake Batata, a shallow Amazonian floodplain lake. Mesocosms were constructed from natural and impacted areas of Lake Batata, to reproduce the sediment‐water interface. The cores were incubated with 0 to 2,388 ind m^–2 of Campsurus notatus nymphs, and the changes in NH₄⁺, DOC, O₂ concentration and bacterioplankton production in the overlying water column were measured. Ammonium efflux (F = 9.8, p < 0.05, multiple regression) and oxygen uptake (F = 11.8, p < 0.05) showed a significant correlation with the density of C. notatus in the cores with natural sediment. No differences on DOC release were observed in cores with natural or impacted sediment. In the cores incubated with natural sediment and nymphs of C. notatus, a significant increase (Two‐way ANOVA, p < 0.05) in bacterial production (0.44 μg C l^–1 h^–1) was observed after 3 hours of incubation. In cores incubated with sediment impacted by bauxite tailings, there was no difference in bacterial production with and without C. notatus. We conclude that C. notatus is an important bioturbator in Lake Batata, increasing the turnover rate of nitrogen (NH₄⁺) at the sediment‐water interface and bacterial production in cores incubated with natural sediment. It is also clear that bauxite tailings reduce the nutrients turnover rates in impacted regions of Lake Batata and influence bacterial production.     

A PLETHORA/PIN-FORMED/auxin network mediates prehaustorium formation in the parasitic plant Striga hermonthica

The parasitic plant Striga (Striga hermonthica) invades the host root through the formation of a haustorium and has detrimental impacts on cereal crops. The haustorium results from the prehaustorium, which is derived directly from the differentiation of the Striga radicle. The molecular mechanisms leading to radicle differentiation shortly after germination remain unclear. In this study, we determined the developmental programs that regulate terminal prehaustorium formation in S. hermonthica at cellular resolution. We showed that shortly after germination, cells in the root meristem undergo multiplanar divisions. During growth, the meristematic activity declines and associates with reduced expression of the stem cell regulator PLETHORA1 and the cell cycle genes CYCLINB1 and HISTONE H4. We also observed a basal localization of the PIN-FORMED (PIN) proteins and a decrease in auxin levels in the meristem. Using the structural layout of the root meristem and the polarity of outer-membrane PIN proteins, we constructed a mathematical model of auxin transport that explains the auxin distribution patterns observed during S. hermonthica root growth. Our results reveal a fundamental molecular and cellular framework governing the switch of S. hermonthica roots to form the invasive prehaustoria.

The parasitic plant Striga hermonthica forms its invasive organ, the prehaustorium, by inducing differentiation of the radicle by arresting cell division.     

Symbiotic bacteria in the relationship between Anaphes nitens (Hymenoptera: Mymaridae) and Gonipterus platensis (Coleoptera: Curculionidae)

The egg parasitoid Anaphes nitens (Hymenoptera: Mymaridae) parasitizes the Eucalyptus snout-beetle Gonipterus platensis (Coleoptera: Curculionidae), one of the main defoliating beetles of Eucalyptus. Outbreaks of this pest are being recorded in areas with low parasitism rates by A. nitens. Endosymbiont bacteria can affect the reproductive characteristics of host insects increasing or decreasing the parasitism rate. The objectives of this study were to identify the presence, phylogeny and transmission modes of endosymbiont bacteria in A. nitens and G. platensis. Six populations of A. nitens and one of G. platensis were evaluated. Genomic DNA from these populations was extracted and nine genera of cell endosymbionts were searched by PCR. Three species of the Enterobacteriaceae family, Erwinia amylovora, Serratia grimesii, Yersinia massiliensis and the cell endosymbiont Rickettsia belli were identified in all A. nitens populations. Only Serratia grimesii was found in G. platensis. The presence of E. amylovora, Y. massiliensis and R. belli in the F1 and F2 generations indicates vertical transmission in A. nitens, while S. grimesii is vertically transmitted in G. platensis.     

Bean common mosaic virus and cucumber mosaic virus naturally infecting Aristolochia spp. plants in Brazil

In April 2022, Aristolochia plants with symptoms of mosaic were observed in a garden at Jardim Botânico Plantarum, Nova Odessa, São Paulo State, Brazil. Potyviridae-like particles were observed by transmission electron microscopy in leaf extracts. Total RNA extracted from symptomatic plants used in RT-PCR with universal and BCMV-specific primers detected the potyvirus bean common mosaic virus (BCMV). The cucumovirus cucumber mosaic virus (CMV) was identified only in Aristolochia littoralis plants that tested negative by RT-PCR for BCMV. Phylogenetic analysis grouped samples of Aristolochia in a different clade among samples of Phaseolus vulgaris. Phylogenetic analysis indicated that the CMV isolate from Aristolochia belongs to the CMV group IA. BCMV was mechanically transmitted to healthy plants of A. fimbriata, Chenopodium quinoa, P. vulgaris cv. Jalo and Macroptilium lathyroides. CMV was mechanically transmitted to plants of A. fimbriata and C. quinoa. The BCMV and CMV were aphid transmitted only by Aphis gossypii to Aristolochia plants. This is the first report of BCMV and CMV infecting Aristolochia plants in Brazil.     

Interaction of shikimic acid with shikimate kinase

The crystal structure of shikimate kinase from Mycobacterium tuberculosis (MtSK) complexed with MgADP and shikimic acid (shikimate) has been determined at 2.3A resolution, clearly revealing the amino acid residues involved in shikimate binding. In MtSK, the Glu61 strictly conserved in SK forms a hydrogen bond and salt-bridge with Arg58 and assists in positioning the guanidinium group of Arg58 for shikimate binding. The carboxyl group of shikimate interacts with Arg58, Gly81, and Arg136, and hydroxyl groups with Asp34 and Gly80. The crystal structure of MtSK-MgADP-shikimate will provide crucial information for elucidation of the mechanism of SK-catalyzed reaction and for the development of a new generation of drugs against tuberculosis.     

Quantification of carvedilol in human plasma by high-performance liquid chromatography coupled to electrospray tandem mass spectrometry: application to bioequivalence study

A rapid, sensitive and specific method to quantify carvedilol in human plasma using metoprolol as the internal standard (IS) is described. The analyte and the IS were extracted from plasma by liquid-liquid extraction using a diethyl-ether solvent. After removed and dried the organic phase, the extracts were reconstituted with a fixed volume of acetonitrile-water (50/50; v/v). The extracts were analyzed by a high performance liquid chromatography coupled to electrospray tandem mass spectrometry (HPLC-MS/MS). Chromatography was performed isocratically on Alltech Prevail C18 5 microm analytical column, (150 mm x 4.6 mm i.d.). The method had a chromatographic run time of 3.5 min and a linear calibration curve over the range 0.1-200 ng ml(-1) (r2>0.997992). The limit of quantification was 0.1 ng ml(-1). This HPLC-MS/MS procedure was used to assess the bioequivalence of two carvedilol 25 mg tablet formulations (carvedilol test formulation from Laboratórios Biosintética Ltda and Coreg from Roche Químicos e Farmacêuticos S.A standard reference formulation). A single 25 mg dose of each formulation was administered to healthy volunteers. The study was conducted using an open, randomized, two-period crossover design with a 2-week wash-out interval. Since the 90% CI for C(max) and AUCs ratios were all inside the 80-125% interval proposed by the US Food and Drug Administration Agency, it was concluded that carvedilol formulation elaborated by Laboratórios Biosintética Ltda is bioequivalent to Coreg formulation for both the rate and the extent of absorption.     

Geographical and experimental contexts modulate the effect of warming on top‐down control: a meta‐analysis

Ecologists have extensively investigated the effect of warming on consumer–resource interactions, with experiments revealing that warming can strengthen, weaken or have no net effect on top‐down control of resources. These experiments have inspired a body of theoretical work to explain the variation in the effect of warming on top‐down control. However, there has been no quantitative attempt to reconcile theory with outcomes from empirical studies. To address the gap between theory and experiment, we performed a meta‐analysis to examine the combined effect of experimental warming and top‐down control on resource biomass and determined potential sources of variation across experiments. We show that differences in experimental outcomes are related to systematic variation in the geographical distribution of studies. Specifically, warming strengthened top‐down control when experiments were conducted in colder regions, but had the opposite effect in warmer regions. Furthermore, we found that differences in the thermoregulation strategy of the consumer and openness of experimental arenas to dispersal can contribute to some deviation from the overall geographical pattern. These results reconcile empirical findings and support the expectation of geographical variation in the response of consumer–resource interactions to warming.     

AP-2 Is the Crucial Clathrin Adaptor Protein for CD4 Downmodulation by HIV-1 Nef in Infected Primary CD4+ T Cells

HIV-1 Nef-mediated CD4 downmodulation involves various host factors. We investigated the importance of AP-1, AP-2, AP-3, V1H-ATPase, β-COP, and ACOT8 for CD4 downmodulation in HIV-1-infected short hairpin RNA (shRNA)-expressing CD4⁺ T cells and characterized direct interaction with Nef by Förster resonance energy transfer (FRET). Binding of lentiviral Nefs to CD4 and AP-2 was conserved, and only AP-2 knockdown impaired Nef-mediated CD4 downmodulation from primary T cells. Altogether, among the factors tested, AP-2 is the most important player for Nef-mediated CD4 downmodulation.