Almost There: Transmission Routes of Bacterial Symbionts between Trophic Levels

Many intracellular microbial symbionts of arthropods are strictly vertically transmitted and manipulate their host's reproduction in ways that enhance their own transmission. Rare horizontal transmission events are nonetheless necessary for symbiont spread to novel host lineages. Horizontal transmission has been mostly inferred from phylogenetic studies but the mechanisms of spread are still largely a mystery. Here, we investigated transmission of two distantly related bacterial symbionts – Rickettsia and Hamiltonella – from their host, the sweet potato whitefly, Bemisia tabaci, to three species of whitefly parasitoids: Eretmocerus emiratus, Eretmocerus eremicus and Encarsia pergandiella. We also examined the potential for vertical transmission of these whitefly symbionts between parasitoid generations. Using florescence in situ hybridization (FISH) and transmission electron microscopy we found that Rickettsia invades Eretmocerus larvae during development in a Rickettsia-infected host, persists in adults and in females, reaches the ovaries. However, Rickettsia does not appear to penetrate the oocytes, but instead is localized in the follicular epithelial cells only. Consequently, Rickettsia is not vertically transmitted in Eretmocerus wasps, a result supported by diagnostic polymerase chain reaction (PCR). In contrast, Rickettsia proved to be merely transient in the digestive tract of Encarsia and was excreted with the meconia before wasp pupation. Adults of all three parasitoid species frequently acquired Rickettsia via contact with infected whiteflies, most likely by feeding on the host hemolymph (host feeding), but the rate of infection declined sharply within a few days of wasps being removed from infected whiteflies. In contrast with Rickettsia, Hamiltonella did not establish in any of the parasitoids tested, and none of the parasitoids acquired Hamiltonella by host feeding. This study demonstrates potential routes and barriers to horizontal transmission of symbionts across trophic levels. The possible mechanisms that lead to the differences in transmission of species of symbionts among species of hosts are discussed

Fluid Micro-Reservoirs Array Design with Auto-Pressure Regulation for High-Speed 3D Printers

Three dimensional (3D) printing technology is rapidly evolving such that printing speed is now a crucial factor in technological developments and future applications. For printing heads based on the inkjet concept, the number of nozzles on the print head is a limiting factor of printing speed. This paper offers a method to practically increase the number of nozzles unlimitedly, and thus to dramatically ramp up printing speed. Fluid reservoirs are used in inkjet print heads to supply fluid through a manifold to the jetting chambers. The pressure in the reservoir’s outlet is important and influences device performance. Many efforts have been made to regulate pressure inside the fluid reservoirs so as to obtain a constant pressure in the chambers. When the number of nozzles is increased too much, the regulation of uniform pressure among all the nozzles becomes too complicated. In this paper, a different approach is taken. The reservoir is divided into an array of many micro-reservoirs. Each micro-reservoir supports one or a few chambers, and has a unique structure with auto-pressure regulation, where the outlet pressure is independent of the fluid level. The regulation is based on auto-compensation of the gravity force and a capillary force having the same dependence on the fluid level; this feature is obtained by adding a wedge in the reservoir with a unique shape. When the fluid level drops, the gravitational force and the capillary force decrease with it, but at similar rates. Terms for the force balance are derived and, consequently, a constant pressure in the fluid micro-reservoir segment is obtained automatically, with each segment being autonomous. This micro reservoir array is suggested for the enlargement of an inkjet print head and the achievement of high-speed 3D printing

FIGURES 65–70 in The oak gall wasps of Israel (Hymenoptera, Cynipidae, Cynipini) - diversity, distribution and life history

FIGURES 65–70. Galls on various Quercus species. 65. Andricus sp. nr. quercusradicis, sexual generation on leaf of Quercus ithaburensis; 66. Neuroterus anthracinus, asexual generation on Quercus ithaburensis; 67. Andricus multiplicatus, sexual generation on Quercus libani; 68. Andricus melikai, sexual generation on Quercus libani; 69. Andricus sp. nr. amenti, sexual generation on Quercus libani; 70. Cerroneuroterus sp. nr. lanuginosus, asexual generation on Quercus libani.Published as part of Shachar, Einat, Melika, George, Inbar, Moshe & Dorchin, Netta, 2018, The oak gall wasps of Israel (Hymenoptera, Cynipidae, Cynipini) - diversity, distribution and life history, pp. 451-498 in Zootaxa 4521 (4) on page 493, DOI: 10.11646/zootaxa.4521.4.1, http://zenodo.org/record/261002

The oak gall wasps of Israel (Hymenoptera, Cynipidae, Cynipini) - diversity, distribution and life history

Shachar, Einat, Melika, George, Inbar, Moshe, Dorchin, Netta (2018): The oak gall wasps of Israel (Hymenoptera, Cynipidae, Cynipini) - diversity, distribution and life history. Zootaxa 4521 (4): 451-498, DOI: 10.11646/zootaxa.4521.4.

Down-Regulation of β-Catenin by Activated p53

β-Catenin is a cytoplasmic protein that participates in the assembly of cell-cell adherens junctions by binding cadherins to the actin cytoskeleton. In addition, it is a key component of the Wnt signaling pathway. Activation of this pathway triggers the accumulation of β-catenin in the nucleus, where it activates the transcription of target genes. Abnormal accumulation of β-catenin is characteristic of various types of cancer and is caused by mutations either in the adenomatous polyposis coli protein, which regulates β-catenin degradation, or in the β-catenin molecule itself. Aberrant accumulation of β-catenin in tumors is often associated with mutational inactivation of the p53 tumor suppressor. Here we show that overexpression of wild-type p53, by either transfection or DNA damage, down-regulates β-catenin in human and mouse cells. This effect was not obtained with transcriptionally inactive p53, including a common tumor-associated p53 mutant. The reduction in β-catenin level was accompanied by inhibition of its transactivation potential. The inhibitory effect of p53 on β-catenin is apparently mediated by the ubiquitin-proteasome system and requires an active glycogen synthase kinase 3β (GSK3β). Mutations in the N terminus of β-catenin which compromise its degradation by the proteasomes, overexpression of dominant-negative ΔF-β-TrCP, or inhibition of GSKβ activity all rendered β-catenin resistant to down-regulation by p53. These findings support the notion that there will be a selective pressure for the loss of wild-type p53 expression in cancers that are driven by excessive accumulation of β-catenin

FIGURES 29–34 in The oak gall wasps of Israel (Hymenoptera, Cynipidae, Cynipini) - diversity, distribution and life history

FIGURES 29–34. Galls on Quercus boissieri. 29. Cynips cornifex, asexual generation; 30. Neuroterus numismalis, sexual generation; 31. Neuroterus anthracinus, asexual generation; 32. Cynips quercus, asexual generation; 33. Cynips divisa, asexual generation; 34. Neuroterus albipes, asexual generation

FIGURES 1–4 in The oak gall wasps of Israel (Hymenoptera, Cynipidae, Cynipini) - diversity, distribution and life history

FIGURES 1–4. Cynipid collection sites on oaks in Israel. 1. Q. libani and Q. cerris. 2. Q. boissieri. 3. Q. ithaburensis. 4. Q. calliprinos. Numbers correspond to the following collection sites: 1. Mt. Hermon, 1780m; 2. Mt. Hermon, 1500m; 3. Mt. Kahal; 4. Odem Forest; 5. En Zivan; 6. Allone HaBashan; 7. Tel Hazeqa; 8. Yehudiyya; 9. Mezar; 10. Mt. Meron; 11. Pa'ar cave; 12. Mt. Addir; 13. Nahal Rakefet; 14. Alonim; 15. Hosha'aya; 16. Bet Keshet Forest; 17. Rehan Forest; 18. HaSharon Forest; 19. Zur Hadassa