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Communication systems within and between plant cells involve the transfer of ions and molecules between compartments, and are essential for development and responses to biotic and abiotic stresses. This in turn requires the regulated movement and fusion of membrane systems with their associated cargo. Recent advances in genomics has provided new resources with which to investigate the evolutionary relationships between membrane proteins across plant species. Members of the soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) are known to play important roles in vesicle trafficking across plant, animal and microbial species. Using recent public expression and transcriptomic data from 9 representative green plants, we investigated the evolution of the SNARE classes and linked protein changes to functional specialization (expression patterns). We identified an additional 3 putative SNARE genes in the model plant Arabidopsis . We found that all SNARE classes have expanded in number to a greater or lesser degree alongside the evolution of multicellularity, and that within-species expansions are also common. These gene expansions appear to be associated with the accumulation of amino acid changes and with sub-functionalization of SNARE family members to different tissues. These results provide an insight into SNARE protein evolution and functional specialization. The work provides a platform for hypothesis-building and future research into the precise functions of these proteins in plant development and responses to the environment.

Plant cytokinins and auxins have recently been proposed as novel cancer therapies, which proceed via different mechanisms; however, their combined use has not been investigated. To the best of our knowledge, the present study was the first to show that the cytokinin ortho-methoxytopolin-riboside (MeoTR) strongly inhibited the proliferation of HeLa cells, the effect of which was synergistically enhanced by auxin indole-3-acetic acid (IAA), while IAA demonstrated to have no cytotoxic effects on cells. MeoTR was found to activate intrinsic and extrinsic caspase-dependent pathways, and IAA potentiated this activation. In addition, these effects were blocked by Z-Val-Ala-Asp-fluoromethylketone (Z-VAD-FM K), a pan-specific-caspase-inhibitor. IAA increased the MeoTR-induced inhibition of B cell lymphoma 2 (Bcl-2) and survivin, whereas IAA-only decreased Bcl-2 expression. MeoTR downregulated phosphorylated (p)-pyruvate dehydrogenase kinase 1, p-Akt and p-glycogen synthase kinase 3β, the effect of which was more potent in combination with IAA, despite the weak effect of IAA alone. LY294002, an Akt-inhibitor, was able to increase the inhibition of p-Akt through MeoTR and combination treatment. IAA and MeoTR increased the proportion of cells in S phase independently. However, the combination treatment induced a further increase. In addition, IAA and MeoTR treatment downregulated protein levels of cyclin A, cyclin-dependent kinase 2 (CDK2) and p-CDK2, and upregulated protein levels of p21 and p27. Furthermore, the combination treatment enhanced these effects, indicating that IAA potentiated the inhibitory effect of MeoTR on HeLa cells via cell cycle progression arrest and accumulation in S phase, coupled with the negative regulation of Bcl-2. In conclusion, the results of the present study suggested that treatment with these two phytohormones in combination, may offer a novel therapeutic strategy for the treatment of malignant cervical cancer. [ABSTRACT FROM AUTHOR]

Several pathways function to remove aberrant mRNA in eukaryotic cells; however, the exact mechanisms underlying the restriction of aberrant mRNA transcription are poorly understood. In this study, we found that MORPHEUS' MOLECULE1 (MOM1) is a key component of this regulatory machinery. The Arabidopsis (Arabidopsis thaliana) mom1-44 mutation was identified by luciferase imaging in transgenic plants harboring a cauliflower mosaic virus 35S promoter-LUCIFERASE transgene lacking the 3'-untranslated region. In the moral-44 mutant, transcriptional read-though occurred in genes with an aberrant RNA structure. Analysis of an RNA-dependent RNA polymerase2 mom1 double mutant revealed that the RNA-directed DNA methylation pathway is not involved in this regulatory process. Moreover, the prevention of aberrant mRNA transcriptional read-through by MOM1 is gene locus and transgene copy number independent. [ABSTRACT FROM AUTHOR]

Epigenetic marks in the form of DNA methylation are involved in the development of germ cells and are important in the maintenance of fertility. However, the controlling system of the on-off switch for DNA methylation largely remains unclear. In this study, the extent of cytosine methylation during the meiotic prophase I in David lily is assessed using high pressure liquid chromatography to evaluate the DNA methylation rates. Comparing the degree of DNA methylation before, during, and after synizesis, both de novo methylation and demethylation occurred. Mainly the methylation level decreased by 21.3% (from 54.8 to 33.5%) during synizesis in the pollen mother cells. The developmental timing of genome-wide DNA methylation acquisition during pollen mother cell development is clarified in this paper. The relative amounts of 5-methyl-deoxycytidine of global methylation in leaf DNA in David lily were also higher than in other species reported. [ABSTRACT FROM AUTHOR]

ATHK1 has been implicated in drought and salt tolerance in Arabidopsis thaliana. In this study, the full-length coding sequence of ATHK1 was introduced into Lycium barbarum L. by Agrobacterium transformation. Our results indicated that the transgenic plants tolerated high concentrations of NaCl or water deprivation and exhibited faster recovery following re-watering compared to wild type plants. Salt- or water-stressed transgenic plants had higher relative water content, proline and soluble protein levels, and lower chlorophyll losses and membrane ion leakage. In addition, they showed higher capacity for antioxidative reactions reflected by reduced hydrogen peroxide (H2O2), superoxide anion radical (O2 −), and lipid peroxide production and increased superoxide dismutase, catalase, and peroxidase activities. The ATHK1 transcript, as shown by reverse transcription polymerase chain reaction, was more abundant under high than low osmolarity in transgenic plants. ATHK1 therefore improved tolerance of L. barbarum to drought and salt stress. [ABSTRACT FROM AUTHOR]

Abstract  Pavement cells have an interlocking jigsaw puzzle-shaped leaf surface pattern. Twenty-three genes involved in the pavement cell morphogenesis were discovered until now. The mutations of these genes through various means lead to pavement cell shape defects, such as loss or lack of interdigitation, the reduction of lobing, gaps between lobe and neck regions in pavement cells, and distorted trichomes. These phenotypes are affected by the organization of microtubules and microfilaments. Microtubule bands are considered corresponding with the neck regions of the cell, while lobe formation depends on patches of microfilaments. The pathway of Rho of plant (ROP) GTPase signaling cascades regulates overall activity of the cytoskeleton in pavement cells. Some other proteins, in addition to the ROPs, SCAR/WAVE, and ARP2/3 complexes, are also involved in the pavement cell morphogenesis. [ABSTRACT FROM AUTHOR]

The combined effect of gallic acid (3,4,5-trihydroxy benzoic acid; GA; 50 mg kg−1 i.p.) and propolis (200 mg kg−1 p.o.) was evaluated against beryllium-induced biochemical and morphological alterations in the liver and kidney. Female albino rats were exposed to beryllium nitrate (1 mg kg−1 i.p.) daily for 28 days followed by treatment with the above mentioned therapeutic agents either individually or in combination for five consecutive days. Exposure to beryllium increased its concentration in the serum, liver and kidney and caused significant alterations in cytochrome P450 enzymes, microsomal lipid peroxidation and protein contents. Beryllium administration significantly altered the aspartate aminotransaminase, alanine aminotransaminase, lactate dehydrogenase, γ-grutamy1 transpeptidase, bilirubin, creatinine and urea in serum, and the activity of acid phosphatase, alkaline phosphatase, adenosine triphosphatase, glucose-6-phophatase and succinic dehydrogenase, triglycerides, cholesterol, protein contents, glycogen contents, lipid peroxidation and glutathione level in the liver and kidney. Beryllium exposure induced severe alterations in hepatorenal morphology, revealing its toxic consequences at a cellular level. Individual administration of GA and propolis reduced the effects on the studied parameters to a degree. Interestingly, GA in conjunction with propolis reversed the alterations in all of the variables examined, highlighting the beneficial effects of combined therapy over monotherapy in the alleviation of beryllium-induced systemic toxicity. [ABSTRACT FROM AUTHOR]