OCP3 is an important modulator of NPR1-mediated jasmonic acid-dependent induced defenses in <Emphasis Type="Italic">Arabidopsis</Emphasis>

Background  

Upon appropriate stimulation, plants increase their level of resistance against future pathogen attack. This phenomenon, known as induced resistance, presents an adaptive advantage due to its reduced fitness costs and its systemic and broad-spectrum nature. In Arabidopsis, different types of induced resistance have been defined based on the signaling pathways involved, particularly those dependent on salicylic acid (SA) and/or jasmonic acid (JA).     

YieJ (CbrC) Mediates CreBC-Dependent Colicin E2 Tolerance in Escherichia coli

Colicin E2-tolerant (known as Cet2) Escherichia coli K-12 mutants overproduce an inner membrane protein, CreD, which is believed to cause the Cet2 phenotype. Here, we show that overproduction of CreD in a Cet2 strain results from hyperactivation of the CreBC two-component regulator, but CreD overproduction is not responsible for the Cet2 phenotype. Through microarray analysis and gene knockout and overexpression studies, we show that overexpression of another CreBC-regulated gene, yieJ (also known as cbrC), causes the Cet2 phenotype.Colicins are protein antibiotics that have various modes of action. They are usually encoded on plasmids and, in many cases, alongside genes encoding colicin immunity factors, which protect colicin-producing cells from the colicin they produce. Of the enzymatic (E) colicins, some carry nuclease activity, including colicin E2, colicin E9, and colicin E3. These three proteins bind to susceptible cells via the surface protein BtuB (the vitamin B₁₂ importer) and, through a series of events that are poorly understood, cross the cell envelope to enter the cytoplasm, where they degrade nucleic acids: colicins E2 and E9 target DNA; colicin E3 targets rRNA (11).Cells can readily become tolerant of E colicins. Mutants usually have lost either the colicin receptor or some protein involved in colicin import. Loss-of-function mutations in btuB confer tolerance of high levels of colicins E2, E9, and E3. Almost 40 years ago, Escherichia coli mutants having a colicin E2-tolerant (Cet2) phenotype were identified. The Cet2 phenotype confers tolerance of colicins E2 and E9 only, while cells remain susceptible to colicin E3, and BtuB is intact (8, 9). Cet2 mutants were shown to overproduce an inner membrane protein (26), and the cet2 mutation was found to be dominant in trans and mapped at 99.9 min on the E. coli chromosome (8, 9). Using the Cet2 mutant RB208 as a source of genomic DNA, a clone able to transform E. coli cells to a Cet2 phenotype was identified. Since this clone carried a gene predicted to encode an inner membrane protein with properties identical to those overproduced in Cet2 mutants, the gene was named cet (15).The cet gene is the last gene in the four-gene cre locus, so cet is also known as creD. The other genes in this locus are creA (hypothetical open reading frame [ORF]); creB, encoding a response regulator; and creC, encoding a sensor kinase. CreB and CreC form a classical two-component regulatory system, and we recently showed that CreBC are activated upon fermentation of glucose in minimal medium or during aerobic growth on minimal medium containing fermentation products, such as pyruvate, lactate, or acetate, as the sole carbon and energy source (10). CreBC controls the expression of a number of genes (the Cre regulon), some of which encode metabolic functions but several of which are hypothetical. One of the most tightly controlled Cre regulon genes is creD (5).We have previously shown that the Cet2 strain RB208 has a point mutation in creC but that creD itself is wild type (5). Since the RB208 genomic clone capable of transforming cells to a Cet2 phenotype carries the whole cre locus, not just creD (15), our hypothesis is that the Cet2 phenotype of the transformant was due to a trans-dominant mutation in the cloned creC mutant allele activating one or more Cre regulon genes and that the Cet2 phenotype may or may not be caused by overexpression of creD. The aims of the experiments described in this paper were to test our hypothesis that the Cet2 phenotype is caused by activating mutations in CreBC and to definitively identify the Cre regulon gene that encodes the colicin E2 tolerance (Cet) protein.     

Molecular evolution of the period gene in Drosophila athabasca

We measured nucleotide variability within and between the three semispecies of the Drosophila athabasca complex, at the period (per) gene by using a polymerase chain reaction-based four-cutter restriction- enzyme analysis. The levels of polymorphism varied considerably between the three semispecies. Our results for per, combined with previous data for X-linked allozymes, suggest that the X chromosome in the western- northern semispecies is less variable than expected under an equilibrium-neutral model. Both the pattern of divergence between the semispecies and a cladistic clustering of per haplotypes support the previously hypothesized grouping of eastern A and eastern B as the two most recently diverged semispecies. A 21-bp in-frame segment in the region of per which shares sequence similarity with the neuronal development gene single minded is deleted in all eastern A and eastern B flies examined but is present in all of the western-northern flies and all other published per sequences. Despite these hints that there may be significant differences at the per gene between the semispecies, especially the western-northern group versus the two eastern groups, there is no compelling evidence that per is involved in the mating song differences between the semispecies.      

Proposed follow up programme after curative resection for lower third oesophageal cancer

Cyclins are indispensable elements of the cell cycle and derangement of their function can lead to cancer formation. Recent studies have also revealed more mechanisms through which cyclins can express their oncogenic potential. This review focuses on the aberrant expression of G1/S cyclins and especially cyclin D and cyclin E; the pathways through which they lead to tumour formation and their involvement in different types of cancer. These elements indicate the mechanisms that could act as targets for cancer therapy.     

Strategies to Improve Survival from Surgery for Heart Valve Implantation in Sheep

Sheep are a commonly used and validated model for cardiovascular research and, more specifically, for heart valve research. Implanting a heart valve on the arrested heart in sheep is complex and is often complicated by difficulties in restarting the heart, causing significant on-table mortality. Therefore, optimal cardioprotective management during heart valve implantation in sheep is essential. However, little is known about successful cardioprotective management techniques in sheep. This article reports our experience in the cardioprotective management of 20 female sheep that underwent surgical aortic valve replacement with a stented tissue-engineered heart valve prosthesis. During this series of experiments, we modified our cardioprotection protocol to improve survival. We emphasize the importance of total body hypothermia and external cooling of the heart. Furthermore, we recommend repeated cardioplegia administration at 20 min intervals during surgery, with the final dosage of cardioplegia given immediately before the de-clamping of the aorta. To reduce the number of defibrillator shocks during a state of ventricular fibrillation (VF), we have learned to restart the heart by reclamping the aorta, administering cardioplegia until cardiac arrest, and de-clamping the aorta thereafter. Despite these encouraging results, more research is needed to finalize a protocol for this procedure.

Sheep are a commonly used and well-validated model for cardiovascular research, particularly for heart valve research, as blood pressure, heart rate, cardiac output, and intracardiac pressures are similar between sheep and humans. Sheep are particularly useful for heart valve research because observable changes in implanted heart valve bioprostheses that would take several years to develop in humans are apparent after only a few months in sheep.^3,11 This feature allows the ovine model to provide relevant and important information about heart valve prostheses in a relatively short time span. The first preclinical step in developing novel heart valves is to test the valve in the pulmonary position in sheep. This surgical technique is relatively easy, as the procedure can be performed on a beating heart in a low-pressure circulation. However, aortic valve surgery is the most frequently performed valvular surgical intervention in human patients.¹² Thus, an important next step is to prove the clinical applicability of a new valve by testing the valve in-vivo in the aortic position in an animal model. In contrast to pulmonary valve replacement, aortic valve replacement must be performed on an arrested heart, which makes the surgical procedure significantly more complex. The sheep is a difficult model for aortic valve replacements due to its narrow annulus, short distance between the annulus and coronary ostia, a short ascending aorta, and difficulty in de-airing of the heart prior to suturing the aortotomy.¹⁹ Consequently, high on-table mortality rates, ranging from 9% to 33%, have been reported.^1,18,21,24 Furthermore, the incidence of mortality during the first 30 d after surgery, directly related to the surgical procedure, is often high, ranging from 17% to 50%.^1,2,16,18,21 Therefore, optimizing cardioprotective strategies during surgery would improve postoperative survival. However, little is known about protective strategies in sheep. In the current series of experiments, we implanted stented, tissue engineered, aortic heart valve prostheses in 20 adult domestic sheep and developed cardioprotective techniques to increase survival rates. In this observational study, we share our experience and insights regarding cardioprotective management to potentially improve the outcome of future surgeries that require an arrested heart in sheep.