Postoperative LV5FU2 combination chemotherapy in patients with curative resected advanced gastric cancer

e15660

Background: To illuminate the effect and toxicity of fortnightly low-dose leucovorin(LV) and fluorouracil(5FU) bolus plus continuous infusion(LV5FU2) postoperative chemotherapy(adjuvant) in patients with curative resected, advanced gastric cancer. Methods: Total 40 patients were enrolled in this study. All patients received LV 20mg/m2(bolus), 5FU 400mg/m2(bolus), 5FU 600mg/m2(24-hour continuous infusion) on day 1, 2, 15, and 16, every 4 weeks(LV5FU2), total 6 cycles. Results: Postoperative chemotherapy was initiated median 19 days after surgery. Total of 238 cycles were administered and median follow-up was 602 days. The median disease-free survival time was 728 days (95% CI, 411∼1045) and 2-year overall survival was 77%. Relapses were reported in 18 (45%) of the patients : Two of 9 patients relapsed in stage IIIA (22.2%), seven of 12 patients relapsed in stage IIIB (58.3%) and nine of 17 patients relapsed in stage IV (52.9%). They were all distant relapsed. Eight patients died. 7 patients died as a result of cancer progression and 1 patient suicided while receiving palliative chemotheraphy for cancer relapse. The grade 3∼4 toxicity of neutropenia 8.4% and anemia 0.4%, neutropenic fever 0.4% were observed. Conclusions: Postoperative LV5FU2 adjuvant chemotherapy is effective and tolerable for the patients with curative resected, advanced gastric cancer.

No significant financial relationships to disclose.

Leptomeningeal carcinomatosis of gastric cancer: Multicenter retrospective analysis of 54 cases

e15658

Background: Leptomeningeal carcinomatosis occurs in approximately 5% of patients with cancer. The most common cancers involving the leptomeninges are breast and lung cancer. However, gastric adenocarcinoma has been rarely reported with leptomeningeal carcinomatosis (LMC). Methods: We analyzed 54 cases of cytological confirmed gastric LMC at 4 institutions from 1994 to 2007. Results: Male to female ratio was 1.5:1. Median age of these patients was 49 years. The majority of patients had advanced disease at the initial diagnosis of gastric cancer. The clinical or pathologic TNM stages of the primary gastric cancer were IV in 38 patients (70%). The median interval from the diagnosis of the primary malignancy to the diagnosis of LMC was 6.3 months (range, 0 - 73.1 months). Of the initial endoscopic finding available 45 patients, Bormann type III and IV were 23 (51%) and 15 (33%) patients, respectively. Headache (85%) and nausea/vomiting (58%) were most common presenting symptoms of LMC. The intrathecal (IT) chemotherapy was administered to 36 patients - mainly with methotraxate alone (59%) or combination with ara- C/hydrocortisone (41%). Median IT treatment number was 7 (range, 1–18). Concomitant radiotherapy or chemotherapy was done in 25 patients and 10 patients, respectively. 17 patients (46%) were achieved cytological negative conversion. Median OS duration from diagnosis of LMC was 6.7 weeks (95% CI; 4.3–9.1 weeks). Clinically, initial advanced stage was predictive value of poor prognosis (P=0.009). But, Cytology negative conversion was predictive value of relatively longer survival duration (P=0.005). And, not only IT chemotherapy but also intravenous chemotherapy had been shown improvement of survival duration (P=0.010, P=0.005, respectively). Conclusions: Although gastric LMC has dismal prognosis, IT and IV chemotherapy could be help to extend survival duration of gastric LMC.

No significant financial relationships to disclose.

Modeling photocurrent transients in organic solar cells

We investigate the transient photocurrents of organic photovoltaic devices in response to a sharp turn-on of illumination, by numerical modeling of the drift-diffusion equations. We show that the photocurrent turn-on dynamics are determined not only by the transport dynamics of free charges, but also by the time required for the population of geminate charge pairs to reach its steady-state value. The dissociation probability of a geminate charge pair is found to be a key parameter in determining the device performance, not only by controlling the efficiency at low intensities, but also in determining the fate of charge pairs formed by bimolecular recombination at high intensities. Bimolecular recombination is shown to reduce the turn-on time at high intensities, since the typical distance traveled by a charge pair is reduced.

DSM-IV pathological gambling in the National Comorbidity Survey Replication

BACKGROUND

Little is known about the prevalence or correlates of DSM-IV pathological gambling (PG).

METHOD

Data from the US National Comorbidity Survey Replication (NCS-R), a nationally representative US household survey, were used to assess lifetime gambling symptoms and PG along with other DSM-IV disorders. Age of onset (AOO) of each lifetime disorder was assessed retrospectively. AOO reports were used to study associations between temporally primary disorders and the subsequent risk of secondary disorders.

RESULTS

Most respondents (78.4%) reported lifetime gambling. Lifetime problem gambling (at least one Criterion A symptom of PG) (2.3%) and PG (0.6%) were much less common. PG was significantly associated with being young, male, and Non-Hispanic Black. People with PG reported first gambling significantly earlier than non-problem gamblers (mean age 16.7 v. 23.9 years, z=12.7, p<0.001), with gambling problems typically beginning during the mid-20s and persisting for an average of 9.4 years. During this time the largest annual gambling losses averaged US$4800. Onset and persistence of PG were predicted by a variety of prior DSM-IV anxiety, mood, impulse-control and substance use disorders. PG also predicted the subsequent onset of generalized anxiety disorder, post-traumatic stress disorder (PTSD) and substance dependence. Although none of the NCS-R respondents with PG ever received treatment for gambling problems, 49.0% were treated at some time for other mental disorders.

CONCLUSIONS

DSM-IV PG is a comparatively rare, seriously impairing, and undertreated disorder whose symptoms typically start during early adulthood and is frequently secondary to other mental or substance disorders that are associated with both PG onset and persistence.

Combination chemotherapy with irinotecan and cisplatin in elderly patients (≥65 years) with extensive-disease small-cell lung cancer

18135

Background: Combination chemotherapy with irinotecan and cisplatin is one of the standard treatments for patients with small-cell lung cancer (SCLC). In elderly patients, however, its efficacy and toxicity has not been well documented. In this Phase II study, we assessed the efficacy and toxicity of combination chemotherapy with irinotecan and cisplatin and examined whether advanced age compromises it in elderly patients with previously untreated extensive-disease small-cell lung cancer (ED-SCLC). Methods: In this study, 43 previously untreated elderly patients (65 years or older) with ED-SCLC were given combination chemotherapy consisting of irinotecan 60mg/m2 on days 1, 8 and 15 and cisplatin 60mg/m2 on days 1. The treatment was repeated every four weeks until patients completed the maximum six cycles. Results: Patients consisted of 34 men and 9 women, whose median age was 70 years (range 65 - 81 years). A complete response and a partial response were observed in 23.3% (10/43) and 58.1% (25/43), respectively. The overall response rate was 81.4% (95% C.I; 69.7 - 93.0%). The overall median survival was 10.3 months (range 7.8 - 12.7 months). The 1-year and 2- year survival rates were 31.8% and 3.4%, respectively. The median progression-free survival was 8.32 months (range 6.8 - 9.8 months). Major toxicities included neutropenia (grade 3 to 4, 55.9%), leukopenia (grade 3 to 4, 46.5%), infection (grade 3 to 4, 37.3%) and diarrhea (grade 3 to 4, 30.3%). Incidence of febrile neutropenia was significantly higher in patients with ECOG performance status 2 compared with ECOG performance 1 (70.7% vs. 5.2%; p < 0.001). There were two treatment related deaths in patients ECOG performance status 2. Conclusions: Our results indicate that combination chemotherapy with irinotecan and cisplatin is an effective treatment for elderly patients with ED-SCLC. However, physicians should be aware of the mortality and morbidity due to myelosuppression following this treatment in elderly ED-SCLC patients with ECOG performance status 2.

No significant financial relationships to disclose.

Irinotecan monotherapy as second-line treatment in advanced pancreatic cancer

15111

Background: The aim of this phase II study was to determine whether second line therapy with single agent irinotecan could provide any clinical benefit in patients with gemcitabine- pretreated advanced pancreatic cancer. Methods: From January 2004 to October 2006, patients with advanced pancreatic cancer previously treated with gemcitabine alone or combination were treated with single agent irinotecan(150 mg/m2, biweekly), until unacceptable toxicity or disease progression. Primary endpoint was response rate with single stage design. Results: Twenty-eight patients were enrolled(22 male, 6 female, median age : 54.5 years (39–76)). Nine patients are still alive and 3 remain on therapy with stable disease. The median number of cycles was 3.5(1–12). Twenty-four patients were assessable for toxicity and 21 for response. The most common toxicities was diarrhea (grade 3, 12.5%). Grade 3 neutropenia in 1 patient was observed. Other hematological and non-hematological toxicities were mild and manageable. Partial responses were observed in 3 patients (3/21, 14%). An additional 9 patients (9/21, 43%) had stable disease as their best response. 12 patients have progressed with a median time-to-progression of 4.0 months. Conclusions: Single-agent irinotecan was tolerated with manageable toxicity, offering encouraging activity as second-line treatment of patients with advanced pancreatic cancer, refractory to gemcitabine.

No significant financial relationships to disclose.

Clinical implication of distinction from clinical features and treatment outcome of malignant lymphoma in Korean childhood and young adult

18534

Background: The Clinicopathologic features of malignant lymphomas vary to geography and differ to age. The goal of this study was to find the implication of distinction from biology, clinical features and treatment outcome of malignant lymphoma in childhood and young adult. Methods: We analysed the clinical features including age, gender, histologic type, and treatment outcome of 294 children and young adults during 13-year period (from May 1993 to November 2005) in Samsung medical center and compared our study to all age group and western childhood and adolescence group on clinical features or treatment outcome in malignant lymphoma. Results: Median age at diagnosis was 20.7 years (range: 0.1–30.1 years). Male to female ratio was 1.37:1, Of 294 cases, there were 248 cases of non-hodgkin’s lymphoma (NHL) (84.3%) and 44 cases of hodgkin’s disease (HD) (15%). This rate was significantly different to rate of all age group (HD= 5.3%) (p=0.001). Of 248 cases of non-hodgkin’s lymphoma, 134 cases (54.0%) were B-lineage and 113 cases (45.6%) were T- or NK-cell lineage. Our study group had higher rates of T- or NK-cell NHL compared to all age group (p=0.001) and western group (p=0.001). Among 248 cases of NHL, the most common histologic type was diffuse large cell lymphoma (DLBL) in our study group. Burkitt’s lymphoma (BL) was the most common histologic types in Western study group. 5-year survival rate (5YSR) was 80.4% and was superior for BL and was inferior for NK/T cell lymphoma. However male T-LBL patients had better outcome in western study group. NHL and T-cell NHL had significantly worse outcomes than HD and B-cell NHL (p=0.049, 0.001, respectively). Comparing age-groups 0–10, 10–20 and 20–30, 5YSR was inferior for the oldest patients only in NHL-, T-cell NHL- and T-cell LBL-groups. Conclusions: Our study suggested environmental and genetic factor was associated with the development of malignant lymphoma.

No significant financial relationships to disclose.

Comparison of the epidermal growth factor receptor gene mutation in matched primary tumor and lymph node metastasis of non-small cell lung cancer

7614

Background: Mutations in epidermal growth factor receptor (EGFR) are considered as a strong predictive marker to EGFR tyrosine kinase inhibitors (TKIs) in non-small-cell lung cancer (NSCLC). Recent studies suggested EGFR status may change between primary NSCLC and corresponding metastatic site. However, it has not fully been evaluated whether EGFR mutation differs in metastases compared to primary NSCLC. Methods: In total, 128 tumor samples from 64 NSCLC patients were investigated comparing matched 64 primary tumors, and 64 lymph node metastases. The epidermal growth factor receptor mutation status was analyzed by a direct sequencing method (exons 18–21 in EGFR) on tumor samples of primary NSCLC and corresponding lymph node metastasis. Results: In 17.2% of patents (11/64), EGFR mutation was identified in either primary NSCLC or metastasis by DNA sequencing. Six (54.5%) out of eleven cases showed discordance of EGFR mutation in the primary tumor/metastasis site. Two cases showed EGFR mutation in the metastasis but not in the primary tumor, while, in four cases, EGFR mutation was detected in the primary tumor but not in the metastasis site. The majority of discordance of EGFR mutations was identified in exon 19 (83.3%, 5/6). The median overall survival (OS) was 17.7 months (95% confidence interval, 9.4–20.0). Median OS was not varied by the discordance of EGFR mutation status between primary NSCLC and corresponding metastatic site. Conclusions: The status of EGFR mutation in primary NSCLC and that in corresponding metastasis site varied in considerable cases by DNA sequencing. Whether the status of EGFR mutation changes during the process of metastasis remains to be evaluated. Future study to evaluate the correlation of tumour response to TKIs and the discordance of the EGFR mutation status is warranted.

No significant financial relationships to disclose.

ICA and water in Korea--overview

The natural water quality in Korea has improved significantly in the last 20 years since major collective national initiatives were implemented by governmental agencies, non-governmental organizations, and professionals among many others. Recently instrumentation, control, and automation (ICA) technology has become one of the most important technologies for carrying out this task. Korea has become especially well known with a strong reputation for information technology and international business with commercial products like semi-conductors, computers, mobile phones, computer games, and other electronic products. In this paper the background of Korean water quality is reviewed and several of the most significant national projects related to ICA are discussed. The major projects may include the Automatic Monitoring Network of River Water Quality and the Integrated Management System of Wastewater Treatment Plants in Upper Basin Area of Multi-purpose Dams.

Identification of genes in thyrocytes regulated by unfolded protein response by using disulfide bond reducing agent of dithiothreitol

Disulfide bonds are formed between the sulfhydryl groups in two cysteine residues of a protein. The formation of these bonds is necessary for the proper folding of a protein into its active three-dimensional form. In this study, the genes associated with disulfide bond formation of proteins from the rat thyroid cell line, FRTL-5 cell, were investigated using disulfide bond reducing agent of dithiothreitol (DTT), which prevented disulfide formation of newly synthesized proteins. The expression of six genes, they being the cAMP phosphodiesterase 7A1, neuronal cell death inducible putative kinase (NIPK), cytosolic LIM protein (Ajuba), Eker, early growth response 1 and the ferritin heavy chain, was specifically enhanced under both reductive conditions and various endoplasmic reticulum (ER) stresses inducing drugs such as Brefeldin A (BFA), calcium ionophore A23187 (A23187) and tunicamycin. These results suggest that a suitable redox environment is necessary for the correct disulfide bond conformation in thyrocytes in a complex system.

Arabidopsis dynamin-like 2 that binds specifically to phosphatidylinositol 4-phosphate assembles into a high-molecular weight complex in vivo and in vitro

Arabadopsis dynamin-like (ADL) 2, a member of the high-molecular weight (M(r)) dynamin family found in Arabidopsis, has been shown to be targeted to the plastid. In the chloroplast, most of the ADL2 was present in the fraction containing the envelope membranes when analyzed by suborganellar fractionation. Sucrose gradient and gel filtration experiments showed that when associated with membranes, ADL2 existed as a high-M(r) complex, whereas the soluble form existed as a monomer. The recombinant ADL2 expressed in Escherichia coli was present as a high-M(r) form and showed higher GTPase activity at a low NaCl concentration, whereas ADL2 existed as a low-M(r) form with a low level of GTPase activity at a high NaCl concentration. Electron microscopy studies revealed that the purified recombinant ADL2 formed spiral-coiled structures or rings. In the presence of guanosine-5'-O-(3-thio)triphosphate, these structures were transformed into a long rod structure. In contrast, in the presence of GDP, these structures disassembled into oligomers that were shown to be tetramer with 4-fold symmetry. Finally, a lipid-binding assay revealed that recombinant ADL2 purified from E. coli bound specifically to phosphatidylinositol 4-phosphate. Together, these results demonstrated that the biochemical properties of ADL2 were very similar to those of dynamin and other related proteins. Based on this similarity, we propose that ADL2 may be involved in vesicle formation at the chloroplast envelope membrane.

Identification of a signal that distinguishes between the chloroplast outer envelope membrane and the endomembrane system in vivo

Certain small outer envelope membrane proteins of chloroplasts are encoded by the nuclear genome without a cleavable N-terminal transit peptide. We investigated in vivo the targeting mechanism of AtOEP7, an Arabidopsis homolog of the small outer envelope membrane protein. AtOEP7 was expressed as a fusion protein with the green fluorescent protein (GFP) either transiently in protoplasts or stably in transgenic plants. In either case, fluorescence microscopy of transformed cells and protein gel blot analysis of fractionated proteins confirmed that the AtOEP7:GFP fusion protein was targeted to the chloroplast outer envelope membrane. In vivo targeting experiments revealed that two regions, the transmembrane domain (TMD) and its C-terminal neighboring seven-amino acid region, were necessary and sufficient for targeting to the chloroplast outer membrane. Substitution of aspartic acid or lysine residues with glycine residues or scrambling of the amino acid sequence of the seven-amino acid region caused mistargeting to the plasma membrane. Although the amino acid sequence of the TMD is not important for targeting, amino acid residues with large side chains inhibited targeting to the chloroplasts and resulted in the formation of large aggregates in the protoplasts. In addition, introduction of a proline residue within the TMD resulted in inhibition of targeting. Finally, a fusion protein, AtOEP7:NLS:GFP, was targeted efficiently to the chloroplast envelope membranes despite the presence of a nuclear localization signal. On the basis of these results, we conclude that the seven-amino acid region and the TMD are determinants for targeting to the chloroplast outer envelope membrane. The seven-amino acid region plays a critical role in AtOEP7 evading the endomembrane system and entering the chloroplast pathway, and the TMD plays critical roles in migration to the chloroplasts and/or subsequent insertion into the membrane.

Identification of a signal that distinguishes between the chloroplast outer envelope membrane and the endomembrane system in vivo

Certain small outer envelope membrane proteins of chloroplasts are encoded by the nuclear genome without a cleavable N-terminal transit peptide. We investigated in vivo the targeting mechanism of AtOEP7, an Arabidopsis homolog of the small outer envelope membrane protein. AtOEP7 was expressed as a fusion protein with the green fluorescent protein (GFP) either transiently in protoplasts or stably in transgenic plants. In either case, fluorescence microscopy of transformed cells and protein gel blot analysis of fractionated proteins confirmed that the AtOEP7:GFP fusion protein was targeted to the chloroplast outer envelope membrane. In vivo targeting experiments revealed that two regions, the transmembrane domain (TMD) and its C-terminal neighboring seven-amino acid region, were necessary and sufficient for targeting to the chloroplast outer membrane. Substitution of aspartic acid or lysine residues with glycine residues or scrambling of the amino acid sequence of the seven-amino acid region caused mistargeting to the plasma membrane. Although the amino acid sequence of the TMD is not important for targeting, amino acid residues with large side chains inhibited targeting to the chloroplasts and resulted in the formation of large aggregates in the protoplasts. In addition, introduction of a proline residue within the TMD resulted in inhibition of targeting. Finally, a fusion protein, AtOEP7:NLS:GFP, was targeted efficiently to the chloroplast envelope membranes despite the presence of a nuclear localization signal. On the basis of these results, we conclude that the seven-amino acid region and the TMD are determinants for targeting to the chloroplast outer envelope membrane. The seven-amino acid region plays a critical role in AtOEP7 evading the endomembrane system and entering the chloroplast pathway, and the TMD plays critical roles in migration to the chloroplasts and/or subsequent insertion into the membrane.

Identification of a signal that distinguishes between the chloroplast outer envelope membrane and the endomembrane system in vivo

Certain small outer envelope membrane proteins of chloroplasts are encoded by the nuclear genome without a cleavable N-terminal transit peptide. We investigated in vivo the targeting mechanism of AtOEP7, an Arabidopsis homolog of the small outer envelope membrane protein. AtOEP7 was expressed as a fusion protein with the green fluorescent protein (GFP) either transiently in protoplasts or stably in transgenic plants. In either case, fluorescence microscopy of transformed cells and protein gel blot analysis of fractionated proteins confirmed that the AtOEP7:GFP fusion protein was targeted to the chloroplast outer envelope membrane. In vivo targeting experiments revealed that two regions, the transmembrane domain (TMD) and its C-terminal neighboring seven-amino acid region, were necessary and sufficient for targeting to the chloroplast outer membrane. Substitution of aspartic acid or lysine residues with glycine residues or scrambling of the amino acid sequence of the seven-amino acid region caused mistargeting to the plasma membrane. Although the amino acid sequence of the TMD is not important for targeting, amino acid residues with large side chains inhibited targeting to the chloroplasts and resulted in the formation of large aggregates in the protoplasts. In addition, introduction of a proline residue within the TMD resulted in inhibition of targeting. Finally, a fusion protein, AtOEP7:NLS:GFP, was targeted efficiently to the chloroplast envelope membranes despite the presence of a nuclear localization signal. On the basis of these results, we conclude that the seven-amino acid region and the TMD are determinants for targeting to the chloroplast outer envelope membrane. The seven-amino acid region plays a critical role in AtOEP7 evading the endomembrane system and entering the chloroplast pathway, and the TMD plays critical roles in migration to the chloroplasts and/or subsequent insertion into the membrane.

Two-component circuitry in Arabidopsis cytokinin signal transduction

Cytokinins are essential plant hormones that are involved in shoot meristem and leaf formation, cell division, chloroplast biogenesis and senescence. Although hybrid histidine protein kinases have been implicated in cytokinin perception in Arabidopsis, the action of histidine protein kinase receptors and the downstream signalling pathway has not been elucidated to date. Here we identify a eukaryotic two-component signalling circuit that initiates cytokinin signalling through distinct hybrid histidine protein kinase activities at the plasma membrane. Histidine phosphotransmitters act as signalling shuttles between the cytoplasm and nucleus in a cytokinin-dependent manner. The short signalling circuit reaches the nuclear target genes by enabling nuclear response regulators ARR1, ARR2 and ARR10 as transcription activators. The cytokinin-inducible ARR4, ARR5, ARR6 and ARR7 genes encode transcription repressors that mediate a negative feedback loop in cytokinin signalling. Ectopic expression in transgenic Arabidopsis of ARR2, the rate-limiting factor in the response to cytokinin, is sufficient to mimic cytokinin in promoting shoot meristem proliferation and leaf differentiation, and in delaying leaf senescence.

Reductive dechlorination of tetrachloroethylene in soils by Fe(II)-based degradative solidification/stabilization

Fe(II)-based degradative solidification/stabilization (DS/S) is a modification of conventional solidification/stabilization (S/S) that uses Fe(II) as a reducing agent for chlorinated organics while immobilizing inorganic contaminants. Feasibility of the Fe(II)-based DS/S technology in treating soils contaminated with tetrachloroethylene (PCE) was tested in this study. The results of the PCE degradation experiments conducted in the presence of a humic acid suggest that natural organic matter would not significantly interfere with the degradative reaction by the Fe(II)-containing reactive species in DS/S systems. Solid-phase degradation experiments showed that the DS/S technology could effectively treat PCE in soils without substantial production of chlorinated intermediates. A pseudo-first-order rate law reasonably described degradation kinetics. The half-lives of PCE ranged from 13 to 335 days, which are within time spans allowable for typical in-situ DS/S application. Trichloroethylene (TCE) was the only chlorinated product observed in the solid-phase experiments, and its presence was generally transitory with the amount being less than 7% of the initial amount of PCE on a molar basis. A surface reaction appears to control observed PCE degradation kinetics rather than mass transfer to the reactive surface.

Diversity and regulation of plant Ca2+ pumps: insights from expression in yeast

The spatial and temporal regulation of calcium concentration in plant cells depends on the coordinate activities of channels and active transporters located on different organelles and membranes. Several Ca2+ pumps have been identified and characterized by functional expression of plant genes in a yeast mutant (K616). This expression system has opened the way to a genetic and biochemical characterization of the regulatory and catalytic features of diverse Ca2+ pumps. Plant Ca(2+)-ATPases fall into two major types: AtECA1 represents one of four or more members of the type IIA (ER-type) Ca(2+)-ATPases in Arabidopsis, and AtACA2 is one of seven or more members of the type IIB (PM-type) Ca(2+)-ATPases that are regulated by a novel amino terminal domain. Type IIB pumps are widely distributed on membranes, including the PM (plasma membrane), vacuole, and ER (endoplasmic reticulum). The regulatory domain serves multiple functions, including autoinhibition, calmodulin binding, and sites for modification by phosphorylation. This domain, however, is considerably diverse among several type IIB ATPases, suggesting that the pumps are differentially regulated. Understanding of Ca2+ transporters at the molecular level is providing insights into their roles in signaling networks and in regulating fundamental processes of cell biology.

Constitutive over-expression of AtGSK1 induces NaCl stress responses in the absence of NaCl stress and results in enhanced NaCl tolerance in Arabidopsis

GSK3/shaggy-like protein kinases have been shown to play diverse roles in development and signal transduction pathways in various organisms. An Arabidopsis homologue of GSK3/shaggy-like kinase, AtGSK1, has been shown to be involved in NaCl stress responses. In order to further clarify the role of AtGSK1 in NaCl stress responses in plants, we generated transgenic Arabidopsis plants that over-expressed AtGSK1 mRNA. These plants showed enhanced resistance to NaCl stress when assayed either as whole plants or by measurement of root growth on NaCl plates. In addition, AtGSK1 transgenic plants in the absence of NaCl stress showed phenotypic changes, such as accumulation of anthocyanin, that were similar to those observed in wild-type plants under NaCl stress. Transgenic plants accumulated 30-50% more Na+ than did wild-type plants when subjected to NaCl stress, and Ca2+ content was increased by 15-30% in the transgenic plants regardless of the NaCl stress level. Northern blotting revealed that AtGSK1 over-expression induced expression of the NaCl stress-responsive genes AtCP1, RD29A and CHS1 in the absence of NaCl stress. In addition, AtCBL1 and AtCP1 were super-induced in the NaCl-stressed transgenic plants. Taken together, these results suggest that AtGSK1 is involved in the signal transduction pathway(s) of NaCl stress responses in Arabidopsis.

A new dynamin-like protein, ADL6, is involved in trafficking from the trans-Golgi network to the central vacuole in Arabidopsis

Dynamin, a high-molecular-weight GTPase, plays a critical role in vesicle formation at the plasma membrane during endocytosis in animal cells. Here we report the identification of a new dynamin homolog in Arabidopsis named Arabidopsis dynamin-like 6 (ADL6). ADL6 is quite similar to dynamin I in its structural organization: a conserved GTPase domain at the N terminus, a pleckstrin homology domain at the center, and a Pro-rich motif at the C terminus. In the cell, a majority of ADL6 is associated with membranes. Immunohistochemistry and in vivo targeting experiments revealed that ADL6 is localized to the Golgi apparatus. Expression of the dominant negative mutant ADL6[K51E] in Arabidopsis protoplasts inhibited trafficking of cargo proteins destined for the lytic vacuole and caused them to accumulate at the trans-Golgi network. In contrast, expression of ADL6[K51E] did not affect trafficking of a cargo protein, H(+)-ATPase:green fluorescent protein, destined for the plasma membrane. These results suggest that ADL6 is involved in vesicle formation for vacuolar trafficking at the trans-Golgi network but not for trafficking to the plasma membrane in plant cells.