Plodia interpunctella (Lepidoptera: Pyralidae): Intoxication with essential oils isolated from Lippia turbinata (Griseb.) and analysis of neuropeptides and neuropeptide receptors,putative targets for pest control

The Indian meal moth Plodia interpunctella is a pest of stored products worldwide. Plant-derived essential oils with insecticidal activity could be safe products to control this species. The scarce information about the mode of action of most plant-derived products limits their use for the control of insect pests. Here, we demonstrate that an essential oil distilled from Lippia turbinata (“poleo”) has insecticidal activity on P. interpunctella larvae. Furthermore, we performed a comprehensive characterization of P. interpunctella neuroendocrine system, in comparison with other lepidopteran species.     

Characterization of the Net1 cell cycle-dependent regulator of the Cdc14 phosphatase from budding yeast

In the budding yeast Saccharomyces cerevisiae, the multifunctional protein Net1 is implicated in regulating the cell cycle function of the Cdc14 protein phosphatase. Genetic and cell biological data suggest that during interphase and early mitosis Net1 holds Cdc14 within the nucleolus where its activity is suppressed. Upon its transient release from Net1 at late anaphase, active Cdc14 promotes exit from mitosis by dephosphorylating targets in the nucleus and cytoplasm. In this paper we present evidence supporting the proposed role of Net1 in regulating Cdc14 and exit from mitosis. We show that the NH(2)-terminal fragment Net1(1-600) directly binds Cdc14 in vitro and is a highly specific competitive inhibitor of its activity (K(i) = 3 nm) with five different substrates including the physiologic targets Swi5 and Sic1. An analysis of truncation mutants indicates that the Cdc14 binding site is located within a segment of Net1 containing residues 1-341. We propose that Net1 inhibits by occluding the active site of Cdc14 because it acts as a competitive inhibitor, binds to a site located within the catalytic domain (residues 1-374), binds with reduced affinity to a Cdc14 C283S mutant in which an active site Cys is replaced, and is displaced by tungstate, a transition state analog known to bind in the catalytic site of protein-tyrosine phosphatases.     

Mechanisms of block of muscle type CLC chloride channels (Review)

CLC proteins are a nine-member gene family of Cl- channels that have diverse roles in the plasma membrane and in intracellular organelles. The recent structure determination of bacterial CLC homologues by Dutzler et al. was a breakthrough for the structure-function analysis of CLC channels. This review describes the mechanisms of inhibition of muscle type CLC channels by two classes of small organic substances: 9-anthracene carboxylic acid (9AC) and p-chlorophenoxy propionic acid (CPP). Both substances block muscle type CLC channels (CLC-0 and CLC-1) from the intracellular side. For CPP, one could show that it inhibits the individual protopores of the double-barrelled channel. A major difference between the two types of blockers is the extremely slow binding- and unbinding-kinetics of 9AC (time scale of min), compared to that of CPP block (time scale of s), while the general mechanism of block seems to be quite similar. In the case of the chiral CPP only the S(-) enantiomer is effective. Both substances exhibit a strongly voltage-dependent block with strong inhibition at negative voltages and relief of block at depolarizing potentials at which the channels tend to open maximally. A quantitative kinetic model was developed for the CPP block of CLC-0 in which the closed state has a much larger affinity for CPP than the open state and opening of drug-bound channels is greatly slowed compared to drug-free channels. First experiments with mutated CLC-0 channels and with derivatives of CPP strongly support the pore localization of the CPP binding site. This work provides the basis for the use of these small organic substances as tools to investigate the pharmacological properties of mammalian CLC channels guided by the crystallographic structure of bacterial CLC homologues. They might also turn out to be useful to obtain information about the intricate coupling of gating and permeation that characterizes CLC channels.     

Cellular and subcellular localization of annexin IV in rabbit intestinal epithelium, pancreas and liver.

The results of immunoblot analysis performed with a specific monoclonal antibody showed that the intestinal mucosa, pancreas and liver are privileged tissues for the expression of annexin IV. Immunofluorescence labelling of thin frozen sections of these tissues showed a strong concentration of annexin IV along the basolateral domain of the plasma membrane of intestinal absorbing cells, hepatocytes and pancreatic acinar cells, whereas in intestinal mucous secreting cells and centro acinar pancreatic cells, annexin IV was found to be present throughout the cytoplasm.     

Vitamin K-dependent gamma-carboxyglutamic acid formation by kidney microsomes in vitro.

γ-Carboxyglutamic acid has been identified as a constituent of renal tissue in chicken, rat, and rabbit and is depressed by vitamin K-deficiency or dicoumarol diets. Thorough perfusion of rat and rabbit kidneys to remove blood contamination does not remove the γ-carboxyglutamate containing protein(s), which appear to be localized in the cortex. Incubation of kidney microsomes with [¹⁴C]NaHCO₃in vitro results in the post-translational formation of protein bound $\text{[}{}^{14}\text{C]-γ-carboxyglutamic}$ acid. Incorporation is stimulated 1.6- to 34-fold by addition of the active vitamin K 2-methyl, 3-farnesyl, 1,4-naphthoquinone. About 80% of incorporated, non-dialyzable ¹⁴C is situated in the γ-carboxyl group of γ-carboxyglutamic acid.     

Tumorhead distribution to cytoplasmic membrane of neural plate cells is positively regulated by Xenopus p21-activated kinase 1 (X-PAK1)

Tumorhead (TH) regulates neural plate cell proliferation during Xenopus early development, and gain or loss of function prevents neural differentiation. TH shuttles between the nuclear and cytoplasmic/cortical cell compartments in embryonic cells. In this study, we show that subcellular distribution of TH is important for its functions. Targeting TH to the cell cortex/membrane potentiates a TH gain of function phenotype and results in neural plate expansion and inhibition of neuronal differentiation. We have found that TH subcellular localization is regulated, and that its shuttling between the nucleus and the cell cortex/cytoplasm is controlled by the catalytic activity of p21-activated kinase, X-PAK1. The phenotypes of embryos that lack, or have excess, X-PAK1 activity mimic the phenotypes induced by loss or gain of TH functions, respectively. We provide evidence that X-PAK1 is an upstream regulator of TH and discuss potential functions of TH at the cell cortex/cytoplasmic membrane and in the nucleus.