Caenorhabditis elegans LET-413 Scribble is essential in the epidermis for growth,viability, and directional outgrowth of epithelial seam cells

The conserved adapter protein Scribble (Scrib) plays essential roles in a variety of cellular processes, including polarity establishment, proliferation, and directed cell migration. While the mechanisms through which Scrib promotes epithelial polarity are beginning to be unraveled, its roles in other cellular processes including cell migration remain enigmatic. In C. elegans, the Scrib ortholog LET-413 is essential for apical–basal polarization and junction formation in embryonic epithelia. However, whether LET-413 is required for postembryonic development or plays a role in migratory events is not known. Here, we use inducible protein degradation to investigate the functioning of LET-413 in larval epithelia. We find that LET-413 is essential in the epidermal epithelium for growth, viability, and junction maintenance. In addition, we identify a novel role for LET-413 in the polarized outgrowth of the epidermal seam cells. These stem cell-like epithelial cells extend anterior and posterior directed apical protrusions in each larval stage to reconnect to their neighbors. We show that the role of LET-413 in seam cell outgrowth is likely mediated largely by the junctional component DLG-1 discs large, which we demonstrate is also essential for directed outgrowth of the seam cells. Our data uncover multiple essential functions for LET-413 in larval development and show that the polarized outgrowth of the epithelial seam cells is controlled by LET-413 Scribble and DLG-1 Discs large.     

Cardiovascular Responses Induced by Obstructive Apnea Are Enhanced in Hypertensive Rats Due to Enhanced Chemoreceptor Responsivity

Spontaneously hypertensive rats (SHR), like patients with sleep apnea, have hypertension, increased sympathetic activity, and increased chemoreceptor drive. We investigated the role of carotid chemoreceptors in cardiovascular responses induced by obstructive apnea in awake SHR. A tracheal balloon and vascular cannulas were implanted, and a week later, apneas of 15 s each were induced. The effects of apnea were more pronounced in SHR than in control rats (Wistar Kyoto; WKY). Blood pressure increased by 57±3 mmHg during apnea in SHR and by 28±3 mmHg in WKY (p<0.05, n = 14/13). The respiratory effort increased by 53±6 mmHg in SHR and by 34±5 mmHg in WKY. The heart rate fell by 209±19 bpm in SHR and by 155±16 bpm in WKY. The carotid chemoreceptors were then inactivated by the ligation of the carotid body artery, and apneas were induced two days later. The inactivation of chemoreceptors reduced the responses to apnea and abolished the difference between SHR and controls. The apnea-induced hypertension was 11±4 mmHg in SHR and 8±4 mmHg in WKY. The respiratory effort was 15±2 mmHg in SHR and 15±2 mmHg in WKY. The heart rate fell 63±18 bpm in SHR and 52±14 bpm in WKY. Similarly, when the chemoreceptors were unloaded by the administration of 100% oxygen, the responses to apnea were reduced. In conclusion, arterial chemoreceptors contribute to the responses induced by apnea in both strains, but they are more important in SHR and account for the exaggerated responses of this strain to apnea.     

Fairy, tadpole, and clam shrimps (Branchiopoda) in seasonally inundated clay pans in the western Mojave Desert and effect on primary producers

Background

Fairy shrimps (Anostraca), tadpole shrimps (Notostraca), clam shrimps (Spinicaudata), algae (primarily filamentous blue-green algae [cyanobacteria]), and suspended organic particulates are dominant food web components of the seasonally inundated pans and playas of the western Mojave Desert in California. We examined the extent to which these branchiopods controlled algal abundance and species composition in clay pans between Rosamond and Rogers Dry Lakes. We surveyed branchiopods during the wet season to estimate abundances and then conducted a laboratory microcosm experiment, in which dried sediment containing cysts and the overlying algal crust were inundated and cultured. Microcosm trials were run with and without shrimps; each type of trial was run for two lengths of time: 30 and 60 days. We estimated the effect of shrimps on algae by measuring chlorophyll content and the relative abundance of algal species.

Results

We found two species of fairy shrimps (Branchinecta mackini and B. gigas), one tadpole shrimp (Lepidurus lemmoni), and a clam shrimp (Cyzicus setosa) in our wet-season field survey. We collected Branchinecta lindahli in a pilot study, but not subsequently. The dominant taxa were C. setosa and B. mackini, but abundances and species composition varied greatly among playas. The same species found in field surveys also occurred in the microcosm experiment. There were no significant differences as a function of experimental treatments for either chlorophyll content or algal species composition (Microcoleus vaginatus dominated all treatments).

Conclusions

The results suggest that there was no direct effect of shrimps on algae. Although the pans harbored an apparently high abundance of branchiopods, these animals had little role in regulating primary producers in this environment.     

Plasmodium chabaudi: efficacy of artemisinin + curcumin combination treatment on a clone selected for artemisinin resistance in mice

Recent studies have proposed curcumin as a potential partner for artemisinin in artemisinin combination therapies to treat malaria infections. The efficacy of curcumin alone and in combination with artemisinin was evaluated on a clone of Plasmodium chabaudi selected for artemisinin resistance in vivo. The addition of piperine as an enhancer of curcumin activity was also tested.Results indicated that curcumin, both alone and in combination with piperine had only a modest antimalarial effect and was not able to reverse the artemisinin-resistant phenotype or significantly affect growth of the tested clone when used in combination with artemisinin. This is in contrast with previous in vivo work and calls for further experimental evaluation of the antimalarial potential of curcumin.     

Emerging Plasmodium vivax resistance to chloroquine in South America: an overview

The global emergence of Plasmodium vivax strains resistant to chloroquine (CQ) since the late 1980s is complicating the current international efforts for malaria control and elimination. Furthermore, CQ-resistant vivax malaria has already reached an alarming prevalence in Indonesia, East Timor and Papua New Guinea. More recently, in vivo studies have documented CQ-resistant P. vivax infections in Guyana, Peru and Brazil. Here, we summarise the available data on CQ resistance across P. vivax-endemic areas of Latin America by combining published in vivo and in vitro studies. We also review the current knowledge regarding the molecular mechanisms of CQ resistance in P. vivax and the prospects for developing and standardising reliable molecular markers of drug resistance. Finally, we discuss how the Worldwide Antimalarial Resistance Network, an international collaborative effort involving malaria experts from all continents, might contribute to the current regional efforts to map CQ-resistant vivax malaria in South America.     

Effectiveness of silicon sources for in vitro development of gerbera

Plant Cell, Tissue and Organ Culture (PCTOC) - Each species cultured in vitro has specific nutritional requirements on the culture medium. The use of silicon in culture can provide benefits to...     

Interaction of medullary P2 and glutamate receptors mediates the vasodilation in the hindlimb of rat

In the nucleus tractus solitarii (NTS) of rats, blockade of extracellular ATP breakdown to adenosine reduces arterial blood pressure (AP) increases that follow stimulation of the hypothalamic defense area (HDA). The effects of ATP on NTS P2 receptors, during stimulation of the HDA, are still unclear. The aim of this study was to determine whether activation of P2 receptors in the NTS mediates cardiovascular responses to HDA stimulation. Further investigation was taken to establish if changes in hindlimb vascular conductance (HVC) elicited by electrical stimulation of the HDA, or activation of P2 receptors in the NTS, are relayed in the rostral ventrolateral medulla (RVLM); and if those responses depend on glutamate release by ATP acting on presynaptic terminals. In anesthetized and paralyzed rats, electrical stimulation of the HDA increased AP and HVC. Blockade of P2 or glutamate receptors in the NTS, with bilateral microinjections of suramin (10 mM) or kynurenate (50 mM) reduced only the evoked increase in HVC by 75 % or more. Similar results were obtained with the blockade combining both antagonists. Blockade of P2 and glutamate receptors in the RVLM also reduced the increases in HVC to stimulation of the HDA by up to 75 %. Bilateral microinjections of kynurenate in the RVLM abolished changes in AP and HVC to injections of the P2 receptor agonist α,β-methylene ATP (20 mM) into the NTS. The findings suggest that HDA-NTS-RVLM pathways in control of HVC are mediated by activation of P2 and glutamate receptors in the brainstem in alerting-defense reactions.     

Somatic embryogenesis of <Emphasis Type="Italic">Byrsonima intermedia</Emphasis> A. Juss.: induction and maturation via indirect approach

Byrsonima, especially the species Byrsonima intermedia, is an endangered Brazilian plant that has been widely used as food and for its therapeutic characteristics. However, this species faces challenges with sexual propagation, and somatic embryogenesis has emerged as a viable alternative option for propagation. Therefore, this study aimed to establish a protocol for inducing somatic embryogenesis in B. intermedia. For the induction of callus from in vitro seedling leaves, different subcultures (three subcultures, 60 days each) and concentrations of different cytokinins (BAP, TDZ, Kin and ZEA) combined with varying NAA solutions were tested. Different concentrations of NAA were also analyzed in the induction of pro-embryogenic calli. For the induction of embryogenic calli and somatic embryos, the pro-embryogenic calli were subcultured on MS medium without adding growth regulators. The somatic embryos that originated were inoculated on a maturation medium containing different concentrations of gibberellic acid (GA₃). The formation of secondary embryos was also analyzed using different concentrations (0, 2.88, and 8.66 µM) of GA₃ and different types of lids (Conventional lid, Biossama® commercial lid and conventional lid with membranes). The results show that for the induction of somatic embryos, the use of kinetin with NAA presented the formation of somatic embryos in the second (4.76 µM CIN?+?0.54 µM NAA) and third (5.17 µM CIN?+?10.54 µM NAA) subcultures. The use of 28.87 µM GA₃ favored the formation of seedlings. The Biossama lid and 2.88 µM GA₃ showed higher formation of secondary embryos.     

Dihydroxyxanthones prenylated derivatives: synthesis, structure elucidation, and growth inhibitory activity on human tumor cell lines with improvement of selectivity for MCF-7

The synthesis, structure elucidation, and antitumor activity of 11 xanthones are reported, being the compounds 3, 4, 6-8, and 9 described for the first time. Xanthones 1 and 2 were used as building blocks to obtain the prenylated derivatives 3-8. Prenylation was carried out using prenyl bromide in alkaline medium. Dihydropyranoxanthones 9-11 were obtained from compounds 4 and 5 by an oxidative ring closure. The structure of the compounds was established by IR, UV, MS, and NMR ((1)H, (13)C, COSY, HSQC, and HMBC) techniques and for compounds 4, 6, and 11 the structure was confirmed by X-ray crystallographic analysis. The effect of the 11 xanthones on the in vitro growth of four human tumor cell lines, MCF-7 (breast adenocarcinoma), NCI-H460 (non-small cell lung cancer), SF-268 (central nervous system cancer), and UACC-62 (melanoma) is also described.