Drought,heat and salt stress induce the expression of a citrus homologue of an atypical late-embryogenesis Lea5 gene

In a search for genes that are induced in citrus cell suspension in response to salt stress, a cDNA clone with high homology to cotton Lea5 gene was isolated. Data base analysis of the protein deduced from the nucleotide sequence indicates that, like in cotton, the protein from citrus contains regions with significant hydropathic character. The gene, designated C-Lea5, is expressed in citrus leaves as well as cell suspension. The steady-state level of C-Lea5 is increased in cell suspension that is grown in the presence of 0.2 M NaCl. This phenomenon is also observed in leaves of citrus plants irrigated with NaCl and in citrus seedlings which are exposed to drought and heat stress. We suggest that the osmotic stress resulted from elevated level of salt is responsible for the increase in the level of C-Lea5.     

Engineered vascular beds provide key signals to pancreatic hormone-producing cells

The mechanisms underlying early islet graft failure are not entirely clear, but are thought to involve ischemic injury due to delayed vascularization. We hypothesize that blood vessels play an active role in cell-cell communications supporting islet survival and engraftment. To test this hypothesis and to uncouple endothelial cell (EC)-generated signaling stimuli from their nutritional and gas exchange functions, we developed three dimensional (3D) endothelial vessel networks in engineered pancreatic tissues prepared from islets, fibroblasts and ECs. The tri-culture setup, seeded on highly porous biocompatible polymeric scaffolds closely mimics the natural anatomical context of pancreatic vasculature. Enhanced islet survival correlating with formation of functional tube-like endothelial vessels was demonstrated. Addition of foreskin fibroblasts to islet-endothelial cultures promoted tube-like structure formation, which further supported islet survival as well as insulin secretion. Gene expression profiles of EC growth factors, extracellular matrix (ECM), morphogenes and differentiation markers were significantly different in 2D versus 3D culture systems and were further modified upon addition of fibroblasts. Implantation of prevascularized islets into diabetic mice promoted survival, integration and function of the engrafted engineered tissue, supporting the suggested role of ECs in islet survival. These findings present potential strategies for preparation of transplantable islets with increased survival prospects.     

Core temperature measurement by microwave radiometry

A ‘double-container model’ was used for core temperature (T_c) measurement by microwave emission radiometry (MR) of warm fluid inside a tube, placed in a container with a cooler fluid. The intensity of microwaves emitted from the warmer fluid inside the tube were measured using a MR metering device, consisting of an antenna linked to a low-noise radio frequency amplifier (bandwidth 500 MHz, centered at 4.0 GHz). Based on the MR measurements, a T_c prediction model was developed for measuring the temperature of fluid inside a tube, achieving a sensitivity of ±0.5 °C at environmental temperature of 33–37 °C.     

Molecular characterization of salt-stress-associated protein in citrus: protein and cDNA sequence homology to mammalian glutathione peroxidases

A gene encoding for a citrus salt-stress-associated protein (Cit-SAP) was cloned from Citrus sinensis salt-treated cell suspension. The gene, designated csa, was isolated from a cDNA expression library. The partial amino acid sequence of the protein, as well as that deduced from the nucleotide sequence of csa, revealed a considerable homology to mammalian glutathione peroxidase (GP), and to clone 6P229 from tobacco protoplasts. The increased expression of Cit-SAP in NaCl-treated cultured citrus cells and in citrus plants irrigated with saline water, and its similarity to GP, raise the possibility that one of the effects of salt stress in plants may be the increase of the level of free radicals.     

Higher-Order Looping and Nuclear Organization of Tcra Facilitate Targeted RAG Cleavage and Regulated Rearrangement in Recombination Centers

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Highlights? RAG-dependent monoallelic loop formation is linked to monoallelic RAG cleavage ? RAG enrichment, cleavage, and higher-order loop formation occur at the 3′ end of Tcra ? Looping out is a determinant of directed RAG targeting ? ATM-mediated control of looping out is linked to the maintenance of genome stability     

The amyloid-beta rise and gamma-secretase inhibitor potency depend on the level of substrate expression

The amyloid-beta (Abeta) peptide, which likely plays a key role in Alzheimer disease, is derived from the amyloid-beta precursor protein (APP) through consecutive proteolytic cleavages by beta-site APP-cleaving enzyme and gamma-secretase. Unexpectedly gamma-secretase inhibitors can increase the secretion of Abeta peptides under some circumstances. This "Abeta rise" phenomenon, the same inhibitor causing an increase in Abeta at low concentrations but inhibition at higher concentrations, has been widely observed. Here we show that the Abeta rise depends on the beta-secretase-derived C-terminal fragment of APP (betaCTF) or C99 levels with low levels causing rises. In contrast, the N-terminally truncated form of Abeta, known as "p3," formed by alpha-secretase cleavage, did not exhibit a rise. In addition to the Abeta rise, low betaCTF or C99 expression decreased gamma-secretase inhibitor potency. This "potency shift" may be explained by the relatively high enzyme to substrate ratio under conditions of low substrate because increased concentrations of inhibitor would be necessary to affect substrate turnover. Consistent with this hypothesis, gamma-secretase inhibitor radioligand occupancy studies showed that a high level of occupancy was correlated with inhibition of Abeta under conditions of low substrate expression. The Abeta rise was also observed in rat brain after dosing with the gamma-secretase inhibitor BMS-299897. The Abeta rise and potency shift are therefore relevant factors in the development of gamma-secretase inhibitors and can be evaluated using appropriate choices of animal and cell culture models. Hypothetical mechanisms for the Abeta rise, including the "incomplete processing" and endocytic models, are discussed.     

Mating behavior of male deer ticksIxodes dammini (Acari: Ixodidae)

To analyze the sexual behavior of male black-legged deer ticks Ixodes dammini,we collected ticks infesting 202 white-tailed deer. On average, 17.7 males and 8.8 females infested each deer. Field-collected males copulated with a mean of 2.25 females, and virgin males mated with 2.4 females. On experimental hosts, males established sexual contact with feeding females and repelled other males, and about half remained paired after their mate detached. Engorged females continue to be receptive, and males mate more readily with them than with nonfed females. We conclude that male I. damminiare endowed with a repertoire of behaviors which favor an opportunistic mating before seeking a host and a preference for mating with feeding females on the host accompanied by tenacious mate guarding.