The OsNAC24-OsNAP protein complex activates OsGBSSI and OsSBEI expression to fine-tune starch biosynthesis in rice endosperm

Starch accounts for up to 90% of the dry weight of rice endosperm and is a key determinant of grain quality. Although starch biosynthesis enzymes have been comprehensively studied, transcriptional regulation of starch-synthesis enzyme-coding genes (SECGs) is largely unknown. In this study, we explored the role of a NAC transcription factor, OsNAC24, in regulating starch biosynthesis in rice. OsNAC24 is highly expressed in developing endosperm. The endosperm of osnac24 mutants is normal in appearance as is starch granule morphology, while total starch content, amylose content, chain length distribution of amylopectin and the physicochemical properties of the starch are changed. In addition, the expression of several SECGs was altered in osnac24 mutant plants. OsNAC24 is a transcriptional activator that targets the promoters of six SECGs; OsGBSSI, OsSBEI, OsAGPS2, OsSSI, OsSSIIIa and OsSSIVb. Since both the mRNA and protein abundances of OsGBSSI and OsSBEI were decreased in the mutants, OsNAC24 functions to regulate starch synthesis mainly through OsGBSSI and OsSBEI. Furthermore, OsNAC24 binds to the newly identified motifs TTGACAA, AGAAGA and ACAAGA as well as the core NAC-binding motif CACG. Another NAC family member, OsNAP, interacts with OsNAC24 and coactivates target gene expression. Loss-of-function of OsNAP led to altered expression in all tested SECGs and reduced the starch content. These results demonstrate that the OsNAC24-OsNAP complex plays key roles in fine-tuning starch synthesis in rice endosperm and further suggest that manipulating the OsNAC24-OsNAP complex regulatory network could be a potential strategy for breeding rice cultivars with improved cooking and eating quality.

Mapping and validation of quantitative trait loci associated with dorsal aleurone thickness in rice (Oryza sativa)

KEY MESSAGE

Mapping of QTLs for dorsal aleurone thickness (DAT) was performed using chromosome segment substitution lines in rice. Three QTLs, qDAT3.1, qDAT3.2, and qDAT7.1, were detected in multiple environments. As a specified endosperm cell type, the aleurone has an abundance of various nutrients. Increasing the number of aleurone layers is a practicable way of developing highly nutritious cereals. Identifying genes that can increase aleurone thickness is useful for the breeding of aleurone traits to improve the nutritional and health values of rice. Here, we found that iodine staining could efficiently distinguish the aleurone layers, which revealed great variation of the aleurone thickness in rice, especially at the dorsal side of the seed. Therefore, we used a population of chromosome segmental substitution lines (CSSLs) derived from Koshihikari and Nona Bokra for quantitative trait locus (QTL) analysis of the dorsal aleurone thickness (DAT). Three QTLs, qDAT3.1, qDAT3.2, and qDAT7.1, were detected in multiple seasons. Among these, qDAT3.2 colocalizes with Hd6 and Hd16, two QTLs previously identified to regulate the heading date of Koshihikari, explaining the negative correlation between the DAT and days to heading (DTH) in rice. We also provide evidence that early-heading ensures the filling of rice seed under a relatively high temperature to promote aleurone thickening. qDAT7.1, the most stable QTL expressed in different environments, functions independently from heading date. Although Nona Bokra has a lower DAT, its qDAT7.1 allele significantly increased DAT in rice, which was further validated using two near-isogenic lines (NILs). These findings pave the way for further gene cloning of aleurone-related QTLs and may aid the development of highly nutritious rice.

High-resolution quantitative trait locus mapping for rice grain quality traits using genotyping by sequencing

Rice is a major food crop that sustains approximately half of the world population. Recent worldwide improvements in the standard of living have increased the demand for high-quality rice. Accurate identification of quantitative trait loci (QTLs) for rice grain quality traits will facilitate rice quality breeding and improvement. In the present study, we performed high-resolution QTL mapping for rice grain quality traits using a genotyping-by-sequencing approach. An F₂ population derived from a cross between an elite japonica variety, Koshihikari, and an indica variety, Nona Bokra, was used to construct a high-density genetic map. A total of 3,830 single nucleotide polymorphism markers were mapped to 12 linkage groups spanning a total length of 2,456.4 cM, with an average genetic distance of 0.82 cM. Seven grain quality traits-the percentage of whole grain, percentage of head rice, percentage of area of head rice, transparency, percentage of chalky rice, percentage of chalkiness area, and degree of chalkiness-of the F₂ population were investigated. In total, 15 QTLs with logarithm of the odds (LOD) scores >4 were identified, which mapped to chromosomes 6, 7, and 9. These loci include four QTLs for transparency, four for percentage of chalky rice, four for percentage of chalkiness area, and three for degree of chalkiness, accounting for 0.01%-61.64% of the total phenotypic variation. Of these QTLs, only one overlapped with previously reported QTLs, and the others were novel. By comparing the major QTL regions in the rice genome, several key candidate genes reported to play crucial roles in grain quality traits were identified. These findings will expedite the fine mapping of these QTLs and QTL pyramiding, which will facilitate the genetic improvement of rice grain quality.

OsNAC129 Regulates Seed Development and Plant Growth and Participates in the Brassinosteroid Signaling Pathway

Grain size and the endosperm starch content determine grain yield and quality in rice. Although these yield components have been intensively studied, their regulatory mechanisms are still largely unknown. In this study, we show that loss-of-function of OsNAC129, a member of the NAC transcription factor gene family that has its highest expression in the immature seed, greatly increased grain length, grain weight, apparent amylose content (AAC), and plant height. Overexpression of OsNAC129 had the opposite effect, significantly decreasing grain width, grain weight, AAC, and plant height. Cytological observation of the outer epidermal cells of the lemma using a scanning electron microscope (SEM) revealed that increased grain length in the osnac129 mutant was due to increased cell length compared with wild-type (WT) plants. The expression of OsPGL1 and OsPGL2, two positive grain-size regulators that control cell elongation, was consistently upregulated in osnac129 mutant plants but downregulated in OsNAC129 overexpression plants. Furthermore, we also found that several starch synthase-encoding genes, including OsGBSSI, were upregulated in the osnac129 mutant and downregulated in the overexpression plants compared with WT plants, implying a negative regulatory role for OsNAC129 both in grain size and starch biosynthesis. Additionally, we found that the expression of OsNAC129 was induced exclusively by abscisic acid (ABA) in seedlings, but OsNAC129-overexpressing plants displayed reduced sensitivity to exogenous brassinolide (BR). Therefore, the results of our study demonstrate that OsNAC129 negatively regulates seed development and plant growth, and further suggest that OsNAC129 participates in the BR signaling pathway.

[Revascularization of the deep femoral artery and its inflow vessels to treat critical limb ischemia in patients with thromboangiitis obliterans:a report of 9 cases]

Objective: To examine the effectiveness of revascularization of the deep femoral artery and its inflow vessels to treat critical limb ischemia in patients with thromboangiitis obliterans (TAO). Methods: The clinical data of 9 TAO patients with critical limb ischemia who underwent deep femoral artery and its inflow revascularization from January 2018 to October 2020 at Department of Vascular Surgery, the First Medical Center, People's Liberation Army General Hospital were retrospectively analyzed.There were all males, aged from 26 to 50 years with onset time from 1 to 7 years.All patients had severe rest pain, and 4 had ischemic ulcers or gangrene.All patients had occlusion of the deep femoral artery origins and(or) its inflow tracts, including 2 ipsilateral common iliac artery occlusion, 4 ipsilateral external iliac artery occlusion, 7 common femoral artery occlusion, and 8 deep femoral artery origins, without the involvement of the contralateral common femoral artery or its inflow tracts.Surgical procedures included femoral endarterectomy with thrombectomy, merge suture, and bypass.Technical success rate, rest pain relief, ulcer healing, patency, amputation rate, and long-term prognosis were recorded. Results: The overall technical success rate was 9/9, including 8 femoral endarterectomies with thrombectomy (with 4 patch-angioplasty with the great saphenous vein, 1 merge suture, and 3 simple sutures), 4 femoral-femoral bypasses with artificial vessels, and 1 superficial femoral artery bypass with the great saphenous vein.Rest pain disappeared after the operation immediately.The follow-up time was 10 to 44 months.All patients survived.The semi-annual patency rate was 9/9, and the one-year patency rate was 6/8.Except for one patient with significantly reduced but unhealed dorsalis ulcer up to now due to continuous heavy tobacco exposure after surgery, all others had no rest pain occurred or recurrence of foot ulcers during the follow-up.Among the 8 patients, 3 cases with recent claudication had continuous moderate tobacco exposure (10 to 20 cigarettes per day or severe passive smoking). Conclusions: For patients with thromboangiitis obliterans involved in the deep femoral artery or its inflow vessels, revascularization should be the primary choice and a good long-term prognosis is promising.Postoperative tobacco exposure (including passive smoking) is of great impact on the prognosis of TAO patients, and smoking cessation education must be reemphasized and reinforced.

Protective effects of miRNA-589 on cerebral ischemia-reperfusion injury

To uncover the potential influence of microRNA-589 (miRNA-589) on cerebral ischemia-reperfusion injury (IRI) and the underlying mechanism, BV2 cells were stimulated by lipopolysaccharide (LPS) or conditioned medium (CM) of primary cortical neurons undergoing oxygen-glucose deprivation (OGD). Regulatory effects of miRNA-589 on the release of inflammatory factors in BV2 cells induced with LPS or CM of primary cortical neurons undergoing OGD were detected by quantitative real-time polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA). The interaction between miRNA-589 and TRAF6 was finally assessed by dual-luciferase reporter gene assay. MiRNA-589 was downregulated in BV2 cells induced with LPS or CM of primary cortical neurons undergoing OGD. Overexpression of miRNA-589 reduced the release of inflammatory factors in LPS or CM-induced BV2 cells. TRAF6 was verified to be the downstream gene of miRNA-589, and its level was negatively regulated by miRNA-589. MiRNA-589 is downregulated following cerebral IRI and alleviates inflammatory response through negatively regulating TRAF6.

Translational Regulation of Plant Response to High Temperature by a Dual-Function tRNAHis Guanylyltransferase in Rice

As sessile organisms, plants have evolved numerous strategies to acclimate to changes in environmental temperature. However, the molecular basis of this acclimation remains largely unclear. In this study we identified a tRNA^His guanylyltransferase, AET1, which contributes to the modification of pre-tRNA^His and is required for normal growth under high-temperature conditions in rice. Interestingly, AET1 possibly interacts with both RACK1A and eIF3h in the endoplasmic reticulum. Notably, AET1 can directly bind to OsARF mRNAs including the uORFs of OsARF19 and OsARF23, indicating that AET1 is associated with translation regulation. Furthermore, polysome profiling assays suggest that the translational status remains unaffected in the aet1 mutant, but that the translational efficiency of OsARF19 and OsARF23 is reduced; moreover, OsARF23 protein levels are obviously decreased in the aet1 mutant under high temperature, implying that AET1 regulates auxin signaling in response to high temperature. Our findings provide new insights into the molecular mechanisms whereby AET1 regulates the environmental temperature response in rice by playing a dual role in tRNA modification and translational control.

[Expression and clinical significance of MIIP and PAK1 in endometrial carcinoma]

Objective: To investigate the expressions of migration and invasion inhibitory protein (MIIP) and p21-activated kinase 1 (PAK1) in endometrial carcinoma (EC) and their correlation with clinicopathological features. Methods: The protein levels of MIIP and PAK1 in 135 paraffin-embedded EC tissues, 55 atypical hyperplasia of endometrium (AHE) and 88 normal endometrium (NE) tissues were quantified by immunohistochemistry, the clincial significance and the relationship of these two proteins were also analyzed. Results: The positive rates of MIIP expression in NE, AHE and EC tissues were 52.3%(46/88), 41.8% (23/55) and 34.8% (47/135), respectively. The expression of MIIP in EC was significantly lower than that of MIIP in NE (P<0.05). The positive rates of PAK1 expression in NE, AHE and EC tissues were 45.5% (40/88), 50.9% (28/55) and 62.2% (84/135), respectively. The expression of PAK1 in EC tissues was significantly higher than that of PAK1 in NE tissues (P<0.05). The expression of MIIP in EC tissues was significantly associated with myometrial invasion, International Federation of Gynaecology and Obstetrics (FIGO) stage and lymph node metastasis (P<0.05). The expression of PAK1 in EC tissues was significantly related with differentiation, myometrial invasion, FIGO stage and lymph node metastasis (P<0.05). The expressions of MIIP and PAK1 in EC tissues were marginally related with the overall survival of patients (P=0.092, P=0.052). The expression of MIIP in EC was negatively correlated with PAK1 (r=-0.329, P<0.001). Conclusions: The down-regulation of MIIP and up-regualtion of PAK1 paticipate in the initiation and development of EC, which are correlated with the poor prognosis of EC. The protein expression of MIIP is inversely related with PAK1 in EC.

GRAIN SIZE AND NUMBER1 Negatively Regulates the OsMKKK10-OsMKK4-OsMPK6 Cascade to Coordinate the Trade-off between Grain Number per Panicle and Grain Size in Rice

Grain number and size are interactive agronomic traits that determine grain yield. However, the molecular mechanisms responsible for coordinating the trade-off between these traits remain elusive. Here, we characterized the rice (Oryza sativa) grain size and number1 (gsn1) mutant, which has larger grains but sparser panicles than the wild type due to disordered localized cell differentiation and proliferation. GSN1 encodes the mitogen-activated protein kinase phosphatase OsMKP1, a dual-specificity phosphatase of unknown function. Reduced expression of GSN1 resulted in larger and fewer grains, whereas increased expression resulted in more grains but reduced grain size. GSN1 directly interacts with and inactivates the mitogen-activated protein kinase OsMPK6 via dephosphorylation. Consistent with this finding, the suppression of mitogen-activated protein kinase genes OsMPK6, OsMKK4, and OsMKKK10 separately resulted in denser panicles and smaller grains, which rescued the mutant gsn1 phenotypes. Therefore, OsMKKK10-OsMKK4-OsMPK6 participates in panicle morphogenesis and acts on a common pathway in rice. We confirmed that GSN1 is a negative regulator of the OsMKKK10-OsMKK4-OsMPK6 cascade that determines panicle architecture. The GSN1-MAPK module coordinates the trade-off between grain number and grain size by integrating localized cell differentiation and proliferation. These findings provide important insights into the developmental plasticity of the panicle and a potential means to improve crop yields.

Thrombolysis during Extended Cardiopulmonary Resuscitation for Autoimmune-Related Pulmonary Embolism

Massive pulmonary embolism (MPE) is one of the potentially reversible causes of cardiac arrest and pulseless electrical activity. At present, a fear of lethal haemorrhage makes thrombolytic therapy prohibitive during cardiopulmonary resuscitation. Blood hypercoagulability in autoimmune disorders (such as autoimmune haemolytic anaemia) carries a risk of MPE. Prompt diagnosis is critical for timely thrombolytic intervention. We reported a 23-year-old female with 10 years medical history of autoimmune haemolytic anaemia developed cardiac arrest in our emergency intensive care unit. Electrocardiogram and echocardiogram findings indicated the possibility of MPE, so fibrinolytic therapy with alteplase was administered along with prolonged cardiopulmonary resuscitation. Her neurological recovery was generally good, and no major bleeding occurred. MPE was confirmed by computed tomography pulmonary angiography afterwards. We regard that once there is presumptive diagnosis of MPE, initiating early thrombolysis during cardiopulmonary resuscitation may be considered. (Hong Kong j.emerg.med. 2016;23:180-185)

Multiple variants in 5q31.1 are associated with systemic lupus erythematosus susceptibility and subphenotypes in the Han Chinese population

BACKGROUND

A previous study provided evidence for a genetic association between PPP2CA on 5q31.1 and systemic lupus erythematosus (SLE) across multi-ancestral cohorts, but failed to find significant evidence for an association in the Han Chinese population.

OBJECTIVES

To explore the association between this locus and SLE using data from our previously published genome-wide association study (GWAS).

METHODS

Single-nucleotide polymorphisms (SNPs) rs7726414 and rs244689 (near TCF7 and PPP2CA in 5q31.1) were selected as candidate independent associations from a large-scale study in a Han Chinese population consisting of 1047 cases and 1205 controls. Subsequently, 3509 cases and 8246 controls were genotyped in two further replication studies. We then investigated the SNPs' associations with SLE subphenotypes and gene expression in peripheral blood mononuclear cells.

RESULTS

Highly significant associations with SLE in the Han Chinese population were detected for SNPs rs7726414 and rs244689 by combining the genotype data from our previous GWAS and two independent replication cohorts. Further conditional analyses indicated that these two SNPs contribute to disease susceptibility independently. A significant association with SLE, age at diagnosis < 20 years, was found for rs7726414 (P = 0·001). The expression levels of TCF7 and PPP2CA messenger RNA in patients with SLE were significantly decreased compared with those in healthy controls.

CONCLUSIONS

This study found evidence for multiple associations with SLE in 5q31.1 at genome-wide levels of significance for the first time in a Han Chinese population, in a combined genotype dataset. These findings suggest that variants in the 5q31.1 locus not only provide novel insights into the genetic architecture of SLE, but also contribute to the complex subphenotypes of SLE.

[Clinical application of adult comorbidity evaluation-27 in endometrial cancer]

Objective: To investigate the significant role of the clinical application of adult comorbidity evaluation-27 (ACE-27) in endometrial cancer (EC). Methods: A total of 847 EC patients were included during Jan. 1985 to Dec. 2015 from Tianjin Medical University General Hospital. The clinical data of the patients were collected and analyzed retrospectively. All of the patients were received operation with no chemotherapy and radiotherapy before operation. The average age was 57.6 years old (range from 25 to 85 years old). The average follow-up period was 59.0 months (range from 2 to 312 months). The comorbidity of the patients was evaluated by ACE-27. EC patients survival was analyzed by Kaplan-Meier survival curve. The relationship between the prognosis of EC and ACE-27, age, body mass index (BMI) , pathological characteristic were showed by Cox modeling. Results: (1) The patient number of score 0, 1, 2 and 3 of ACE-27 in EC patients were respectively 311 (36.7%), 263 (31.1%), 132 (15.6%) and 141 (16.6%) cases. (2) Kaplan-Meier survival curve analysis showed that overall survival time of EC patients was gradually decreased as increased score of ACE-27 (χ²=19.003, P=0.000) . In the patients of BMI<25 kg/m² and BMI 25-<30 kg/m², International Federation of Gynecology and Obstetrics (FIGO) stage Ⅰ, endometrial adenocarcinoma type and the overall survival time of those EC patients were gradually decreased as increased score of ACE-27 (P<0.05) . However, there was no statistically significant difference in overall survival time for patients with BMI ≥30 kg/m², FIGO stage with Ⅱ-Ⅳand non-endometrial adenocarcinoma type (P>0.05). Per unvariate logistic modeling showed that the risk of death in score 3 of ACE-27 was increased compared with score 0 of ACE-27 (OR=2.53, P=0.000) . The overall survival time in EC patients with aged 50-59, 60-69 and ≥70 years old, BMI 25-<30 kg/m² and ≥ 30 kg/m², G₃, FIGO stage Ⅱ-Ⅳ and non-endometrial adenocarcinoma type were significantly decreased compared with those aged <50 years old, BMI < 25 kg/m², G₁, FIGO stage Ⅰ and endometrial adenocarcinoma type (all P<0.05) . Further we found that postoperative chemotherapy or radiotherapy rate were decreased for EC patients with FIGO staging Ⅲ or Ⅳ as the increase of ACE-27 score, but there was no statistically significant difference (P>0.05). (3) Per multivariate logistic modeling showed that the risks of death in score 3 of ACE-27 was increased compared with score 0 of ACE-27 among age-adjusted, BMI, histological grade, FIGO stage and pathologic type (OR=2.40, P=0.000) . Per multivariate logistic modeling showed that, the overall survival time in EC patients with aged 60-69 and ≥70 years old, BMI 25-<30 kg/m² and ≥30 kg/m², FIGO stage Ⅲ-Ⅳ and non- endometrial adenocarcinoma type remain significantly decreased compared with those aged <50 years old, BMI<25 kg/m², FIGO stage Ⅰ and endometrial adenocarcinoma type (P<0.05) , but there was no statistically significant difference in histological grade (P>0.05). Conclusions: ACE-27 may become one of the factors of predictive therapy and the prognosis for EC patients. The detailed clinical data of comorbidity should be collected to evaluate prognosis and therapy plan.

OsHAL3, a Blue Light-Responsive Protein, Interacts with the Floral Regulator Hd1 to Activate Flowering in Rice

In flowering plants, photoperiodic flowering is controlled by a complicated network. Light is one of the most important environmental stimuli that control the timing of the transition from vegetative growth to reproductive development. Several photoreceptors, including PHYA, PHYB, CRY2, and FKF1 in Arabidopsis and their homologs (OsPHYA, OsPHYB, OsPHYC, and OsCRY2) in rice, have been identified to be related to flowering. Our previous study suggests that OsHAL3, a flavin mononucleotide-binding protein, may function as a blue-light sensor. Here, we report the identification of OsHAL3 as a positive regulator of flowering in rice. OsHAL3 overexpression lines exhibited an early flowering phenotype, whereas downregulation of OsHAL3 expression by RNA interference delayed flowering under an inductive photoperiod (short-day conditions). The change in flowering time was not accompanied by altered Hd1 expression but rather by reduced accumulation of Hd3a and MADS14 transcripts. OsHAL3 and Hd1 colocalized in the nucleus and physically interacted in vivo under the dark, whereas their interaction was inhibited by white or blue light. Moreover, OsHAL3 directly bound to the promoter of Hd3a, especially before dawn. We conclude that OsHAL3, a novel light-responsive protein, plays an essential role in photoperiodic control of flowering time in rice, which is probably mediated by forming a complex with Hd1. Our findings open up new perspectives on the photoperiodic flowering pathway.

The miR156-SPL9-DFR pathway coordinates the relationship between development and abiotic stress tolerance in plants

Young organisms have relatively strong resistance to diseases and adverse conditions. When confronted with adversity, the process of development is delayed in plants. This phenomenon is thought to result from the rebalancing of energy, which helps plants to coordinate the relationship between development and stress tolerance; however, the molecular mechanism underlying this phenomenon remains mysterious. In this study, we found that miR156 integrates environmental signals to ensure timely flowering, thus enabling the completion of breeding. Under stress conditions, miR156 is induced to maintain the plant in the juvenile state for a relatively long period of time, whereas under favorable conditions, miR156 is suppressed to accelerate the developmental transition. Blocking the miR156 signaling pathway in Arabidopsis thaliana with 35S::MIM156 (via target mimicry) increased the sensitivity of the plant to stress treatment, whereas overexpression of miR156 increased stress tolerance. In fact, this mechanism is also conserved in Oryza sativa (rice). We also identified downstream genes of miR156, i.e. SQUAMOSA PROMOTER BINDING PROTEIN-LIKE 9 (SPL9) and DIHYDROFLAVONOL-4-REDUCTASE (DFR), which take part in this process by influencing the metabolism of anthocyanin. Our results uncover a molecular mechanism for plant adaptation to the environment through the miR156-SPLs-DFR pathway, which coordinates development and abiotic stress tolerance.

The miR156-SPL9-DFR pathway coordinates the relationship between development and abiotic stress tolerance in plants

Young organisms have relatively strong resistance to diseases and adverse conditions. When confronted with adversity, the process of development is delayed in plants. This phenomenon is thought to result from the rebalancing of energy, which helps plants to coordinate the relationship between development and stress tolerance; however, the molecular mechanism underlying this phenomenon remains mysterious. In this study, we found that miR156 integrates environmental signals to ensure timely flowering, thus enabling the completion of breeding. Under stress conditions, miR156 is induced to maintain the plant in the juvenile state for a relatively long period of time, whereas under favorable conditions, miR156 is suppressed to accelerate the developmental transition. Blocking the miR156 signaling pathway in Arabidopsis thaliana with 35S::MIM156 (via target mimicry) increased the sensitivity of the plant to stress treatment, whereas overexpression of miR156 increased stress tolerance. In fact, this mechanism is also conserved in Oryza sativa (rice). We also identified downstream genes of miR156, i.e. SQUAMOSA PROMOTER BINDING PROTEIN-LIKE 9 (SPL9) and DIHYDROFLAVONOL-4-REDUCTASE (DFR), which take part in this process by influencing the metabolism of anthocyanin. Our results uncover a molecular mechanism for plant adaptation to the environment through the miR156-SPLs-DFR pathway, which coordinates development and abiotic stress tolerance.

Genetic and physiological analysis of a novel type of interspecific hybrid weakness in rice

Hybrid weakness is an important reproductive barrier that hinders genetic exchange between different species at the post-zygotic stage. However, our understanding of the molecular mechanisms underlying hybrid weakness is limited. In this study, we report discovery of a novel interspecific hybrid weakness in a rice chromosome segment substitution line (CSSL) library derived from a cross between the indica variety Teqing (Oryza sativa) and common wild rice (O. rufipogon). The dominant Hybrid weakness i1 (Hwi1) gene from wild rice is genetically incompatible with Teqing and induced a set of weakness symptoms, including growth suppression, yield decrease, impaired nutrient absorption, and the retardation of crown root initiation. Phytohormone treatment showed that salicylic acid (SA) could restore the height of plants expressing hybrid weakness, while other phytohormones appear to have little effect. Fine mapping indicated that Hwi1 is located in a tandem leucine-rich repeat receptor-like kinase (LRR-RLK) gene cluster. Within the 13.2-kb candidate region on the short arm of chromosome 11, there are two annotated LRR-RLK genes, LOC_Os11g07230 and LOC_Os11g07240. The Teqing allele of LOC_Os11g07230 and the wild rice allele of LOC_Os11g07240 encode predicted functional proteins. Based on the genetic inheritance of hybrid weakness, LOC_Os11g07240 is implicated as the candidate gene for Hwi1. Functional analysis of Hwi1 will expand our knowledge of the regulation of hybrid weakness in rice.

MicroRNA-181b expression in prostate cancer tissues and its influence on the biological behavior of the prostate cancer cell line PC-3

We examined microRNA-181b (miRNA) expression in prostate cancer tissues and its effect on the prostate cancer cell line PC-3. Tissues from 27 cases of prostate cancer and 30 samples of normal human prostate were collected by surgical removal. Total miRNA was extracted, and the relative expression of miR-181b was quantified using RT-PCR. miR-181b ASO was transfected into prostate cancer PC-3 cells. miR-181b expression in transfected and non-transfected cells was measured using RT-PCR. Changes in cell apoptosis were measured using flow cytometry. MTT and cell growth curve methods were used to assess the influence of miR-181b expression on cell proliferation. The changes in cell invasive ability in vitro were detected using the Transwell chamber method. miR-181b was up-regulated in the prostate cancer tissues compared with the normal prostate samples. It was down-regulated after miR-181b ASO transfection into the prostate cancer PC-3 cells. Down-regulation of miR-181b in the PC-3 cell induced apoptosis, inhibited proliferation, and depressed invasion of PC-3 cells in vitro. As miR-181b is over-expressed in prostate cancer, its down-regulation could have potential as gene therapy for prostate cancer by inducing apoptosis, inhibiting proliferation and depressing invasion by cancer cells.

Identification of quantitative trait Loci for lipid metabolism in rice seeds

Plant seed oil is important for human dietary consumption and industrial application. The oil trait is controlled by quantitative trait loci (QTLs), but no QTLs for fatty acid composition are known in rice, the monocot model plant. QTL analysis was performed using F(2) and F(2:3) progeny from a cross of an indica variety and a japonica variety. Gas chromatography-mass spectrometry (GC-MS) analysis revealed significant differences between parental lines in fatty acid composition of brown rice oil, and 29 associated QTLs in F(2) and/or F(2:3) populations were identified throughout the rice genome, except chromosomes 9 and 10. Eight QTLs were repeatedly identified in both populations across different environments. Five loci pleiotropically controlled different traits, contributing to complex interactions of oil with fatty acids and between fatty acids. Nine rice orthologs of Arabidopsis genes encoding key enzymes in lipid metabolism co-localized with 11 mapped QTLs. A strong QTL for oleic (18:1) and linoleic (18:2) acid were associated with a rice ortholog of a gene encoding acyl-CoA:diacylglycerol acyltransferase (DGAT), and another for palmitic acid (16:0) mapped similarly to the acyl-ACP thioesterase (FatB) gene ortholog. Our approach rapidly and efficiently identified candidate genes for mapped QTLs controlling fatty acid composition and oil concentration, providing information for improving rice grain quality by marker assisted selection.

Rice carotenoid β-ring hydroxylase CYP97A4 is involved in lutein biosynthesis

Lutein is the most abundant plant carotenoid and plays essential roles in photosystem assembly and stabilization, as well as protection against photostress. To date, only a few lutein biosynthesis genes have been identified in crop plants. In this study, the rice Cyt P450 gene CYP97A4 encoding a carotenoid β-ring hydroxylase was shown to be involved in lutein biosynthesis. The results revealed that CYP97A4 was preferentially expressed in leaf compared with spikelet, sheath, stalk and root, and encoded a protein localized at the subcellular level to the chloroplasts. Compared with the wild type, the three allelic mutants of CYP97A4 displayed lutein reductions of 12-24% with substantially increased α-carotene, while Chl a/b levels were unaltered. The increased α-carotene in the mutants led to greater sensitivity under high light stress. Similarly, reactive oxygen species (ROS) imaging of leaves treated with intense light showed that the mutants generally accumulated greater levels of ROS compared with wild-type plants, which probably caused detrimental effects to the plant photosystem. In conclusion, this study demonstrated the important role of CYP97A4 in α-carotene hydroxylation in rice, and knock-out of the gene reduced lutein and increased α-carotene, contributing to sensitivity to intense light.

The usefulness of phosphorylated-signal transduction and activators of transcription 3 in detecting prostate cancer from negative biopsies

AIMS

To avoid the misdiagnosis of prostate cancer (PCA), many patients receive repeated biopsies, despite receiving prior negative biopsies for PCA. Signal transduction and activators of transcription 3 (STAT3), a component of the JAK-STAT signaling pathway, can be activated by tyrosine phosphorylation as P-STAT3 and involved in the regulation of cellular growth, survival and oncogenesis. We aimed to assess the reliability of detecting PCA from the expression of P-STAT3 in prostate tissue previously designated as a negative biopsy.

METHODS

Prostate tissues were obtained from the biopsies of 52 patients with localized PCA as well as from the biopsies of 80 patients free of PCA. Expression of P-STAT3 in these specimens was examined by immunohistochemical staining (IHC) and used to distinguish tissue with PCA from tissue designated as benign during a biopsy procedure.

RESULTS

P-STAT3 staining intensities in all samples (initial negative biopsies, cancer positive cores and other negative cores from the same-batch biopsies) of PCA patients was significantly higher than that of benign patients (F = 23.664, P < 0.001). Analysis of the receiver operating characteristics (ROC) curve showed that the area under curve (AUC) for P-STAT3 staining was 0.785. When positive immuno-labeling of P-STAT3 in samples from initial biopsies was used as a marker for PCA, it showed relatively high sensitivity (80.8%) and specificity (76.3%).

CONCLUSIONS

IHC of P-STAT3 could be utilized to detect PCA patients with initial negative biopsies. As a result, it can be a potential adjunctive tool for current PCA diagnostic programs. P-STAT3 can predict the onset of PCA up to 40 months earlier than currently used diagnostic approaches.

Fine mapping and candidate gene analysis of spd6, responsible for small panicle and dwarfness in wild rice (Oryza rufipogon Griff.)

Identification of genes in rice that affect production and quality is necessary for improving the critical global food source. CSSL58, a chromosome segment substitution line (CSSL) containing a chromosome segment of Oryza rufipogon in the genetic background of the indica cultivar Teqing showed significantly smaller panicles, fewer grains per panicle, smaller grains and dwarfness compared with the recurrent parent Teqing. Genetic analysis of the BC(4)F(1) and BC(4)F(2) generations, derived from a cross between CSSL58 and Teqing, showed that these traits are controlled by the recessive gene spd6, which mapped to the short arm of chromosome 6. Fine mapping and high-resolution linkage analysis using 24,120 BC(4)F(3) plants and markers flanking spd6 were carried out, and the gene was localized to a 22.4 kb region that contains four annotated genes according to the genome sequence of japonica Nipponbare. Phenotypic evaluation of the nearly isogenic line NIL(spd6) revealed that spd6 from wild rice has pleiotropic effects on panicle number per plant, grain size, grain weight, grain number per panicle and plant height, suggesting that this gene might play an important role in the domestication of rice. The discovery of spd6 may ultimately be useful for the design and breeding of crops with high grain yield and quality.

A previously unknown zinc finger protein, DST, regulates drought and salt tolerance in rice via stomatal aperture control

Abiotic stresses, such as drought and salinity, lead to crop growth damage and a decrease in crop yields. Stomata control CO(2) uptake and optimize water use efficiency, thereby playing crucial roles in abiotic stress tolerance. Hydrogen peroxide (H(2)O(2)) is an important signal molecule that induces stomatal closure. However, the molecular pathway that regulates the H(2)O(2) level in guard cells remains largely unknown. Here, we clone and characterize DST (drought and salt tolerance)-a previously unknown zinc finger transcription factor that negatively regulates stomatal closure by direct modulation of genes related to H(2)O(2) homeostasis-and identify a novel pathway for the signal transduction of DST-mediated H(2)O(2)-induced stomatal closure. Loss of DST function increases stomatal closure and reduces stomatal density, consequently resulting in enhanced drought and salt tolerance in rice. These findings provide an interesting insight into the mechanism of stomata-regulated abiotic stress tolerance, and an important genetic engineering approach for improving abiotic stress tolerance in crops.

Identification of quantitative trait loci for rice quality in a population of chromosome segment substitution lines

The demand for high quality rice represents a major issue in rice production. The primary components of rice grain quality include appearance, eating, cooking, physico-chemical, milling and nutritional qualities. Most of these traits are complex and controlled by quantitative trait loci (QTLs), so the genetic characterization of these traits is more difficult than that of traits controlled by a single gene. The detection and genetic identification of QTLs can provide insights into the genetic mechanisms underlying quality traits. Chromosome segment substitution lines (CSSLs) are effective tools used in mapping QTLs. In this study, we constructed 154 CSSLs from backcross progeny (BC(3)F(2)) derived from a cross between 'Koshihikari' (an Oryza sativa L. ssp. japonica variety) as the recurrent parent and 'Nona Bokra' (an O. sativa L. ssp. indica variety) as the donor parent. In this process, we carried out marker-assisted selection by using 102 cleaved amplified polymorphic sequence and simple sequence repeat markers covering most of the rice genome. Finally, this set of CSSLs was used to identify QTLs for rice quality traits. Ten QTLs for rice appearance quality traits were detected and eight QTLs concerned physico-chemical traits. These results supply the foundation for further genetic studies and breeding for the improvement of grain quality.

Genetic control of rice plant architecture under domestication

The closely related wild rice species Oryza rufipogon is considered the progenitor of cultivated rice (Oryza sativa). The transition from the characteristic plant architecture of wild rice to that of cultivated rice was one of the most important events in rice domestication; however, the molecular basis of this key domestication transition has not been elucidated. Here we show that the PROG1 gene controls aspects of wild-rice plant architecture, including tiller angle and number of tillers. The gene encodes a newly identified zinc-finger nuclear transcription factor with transcriptional activity and is mapped on chromosome 7. PROG1 is predominantly expressed in the axillary meristems, the site of tiller bud formation. Rice transformation experiments demonstrate that artificial selection of an amino acid substitution in the PROG1 protein during domestication led to the transition from the plant architecture of wild rice to that of domesticated rice.

Fine mapping of Spr3, a locus for spreading panicle from African cultivated rice (Oryza glaberrima Steud.)

A CSSL (chromosome segment substitution line), SG-64, carrying a segment of chromosome 4 from African cultivated rice (CG-14) in the genetic background of var. Wuyujing-7 (japonica), showed a spreading panicle, which was different significantly from that of Wuyujing-7 with an erect compact panicle. The gene controlling a spreading panicle is referred to as Spr3, and is mapped on chromosome 4. To uncover the genetic basis of Spr3, a large F(2) population derived from cross between SG-64 and Wuyujing-7 was constructed for fine mapping of the Spr3 locus. The high-resolution linkage analysis revealed that the Spr3 locus was narrowed down to a 4.6-kb region. The delimited genomic DNA regions of Wuyujing-7 and CG-14 were sequenced and compared. Sequence mutations between Wuyujing-7 and CG-14 were evident and the candidate genes for the locus were predicted. Publicly available databases were searched for homologous cDNA sequences. However, any coding regions or other meaningful sequences for the Spr3 locus were not found within this delimited region. This result suggested that Spr3 is an unknown genetic factor in controlling the outspreading of the primary branches in rice inflorescence. In addition, NIL(Spr3) exhibited seed shattering. The formation of spreading panicle was accompanied by a few undesirable traits and the spreading panicle links with seed shattering suggest that the spreading panicle was likely lost during the domestication and selection for high seed productivity of cultivated rice.

Overexpression of the trehalose-6-phosphate phosphatase gene OsTPP1 confers stress tolerance in rice and results in the activation of stress responsive genes

Trehalose plays a protective role in yeast and microorganisms under abiotic stresses. However, little is known about its role in higher plants when subjected to environmental challenges. A systematic search of rice databases discovered a large TPS/TPP gene family in the rice genome, which is similar to that found in Arabidopsis thaliana, especially in the gene family structure. Expression analysis demonstrated that OsTPP1 was initially and transiently up-regulated after salt, osmotic and abscisic acid (ABA) treatments but slowly up-regulated under cold stress. OsTPP1 overexpression in rice enhanced tolerance to salt and cold stress. Analysis of the overexpression lines revealed that OsTPP1 triggered abiotic stress response genes, which suggests a possible transcriptional regulation pathway in stress induced reprogramming initiated by OsTPP1. The current study revealed the mechanism of an OsTPP gene involved in stress tolerance in rice and also suggested the use of OsTPP1 in abiotic stress engineering of crops.

Duration of improved muscle glucose uptake after acute exercise in obese Zucker rats

Skeletal muscle is insulin resistant in the obese Zucker rat. Endurance training reduces muscle insulin resistance, but the effects of a single acute exercise session on muscle insulin resistance in the obese Zucker rat are unknown. Therefore, insulin responsiveness of muscle glucose uptake was measured in 15-week-old obese rats either 1, 48, or 72 hours after two hours of intermittent exercise (30:30 min; work:rest). Hindlimbs of sedentary lean (LS) and obese (OS) rats and exercised obese (OE) rats were perfused after a 10-hour fast under both basal (0 mU x ml(-1)) and maximal (20 mU x ml(-1)) insulin concentrations to measure net glucose uptake. Insulin responsiveness of net glucose uptake was significantly reduced in OS compared to LS (8.5 +/- 1.6 vs 15.3 +/- 2.0 micromol x g(-1) x h(-1), respectively). Compared to OS, insulin responsiveness of net glucose uptake was significantly increased by 56% and 80% at 1 hour and 48 hours after acute exercise. However, 72 hours after acute exercise, the increased insulin responsiveness of net glucose uptake was no longer evident. These results indicate that improved responsiveness of muscle glucose uptake persists for at least 48 hours after two hours of acute intermittent exercise in 15-week-old obese Zucker rats.

A rice quantitative trait locus for salt tolerance encodes a sodium transporter

Many important agronomic traits in crop plants, including stress tolerance, are complex traits controlled by quantitative trait loci (QTLs). Isolation of these QTLs holds great promise to improve world agriculture but is a challenging task. We previously mapped a rice QTL, SKC1, that maintained K(+) homeostasis in the salt-tolerant variety under salt stress, consistent with the earlier finding that K(+) homeostasis is important in salt tolerance. To understand the molecular basis of this QTL, we isolated the SKC1 gene by map-based cloning and found that it encoded a member of HKT-type transporters. SKC1 is preferentially expressed in the parenchyma cells surrounding the xylem vessels. Voltage-clamp analysis showed that SKC1 protein functions as a Na(+)-selective transporter. Physiological analysis suggested that SKC1 is involved in regulating K(+)/Na(+) homeostasis under salt stress, providing a potential tool for improving salt tolerance in crops.

QTLs for Na+ and K+ uptake of the shoots and roots controlling rice salt tolerance

An F2 and an equivalent F3 population derived from a cross between a high salt-tolerance indica variety, Nona Bokra, and a susceptible elite japonica variety, Koshihikari, were produced. We performed QTL mapping for physiological traits related to rice salt-tolerance. Three QTLs for survival days of seedlings (SDSs) under salt stress were detected on chromosomes 1, 6 and 7, respectively, and explained 13.9% to 18.0% of the total phenotypic variance. Based on the correlations between SDSs and other physiological traits, it was considered that damage of leaves was attributed to accumulation of Na+ in the shoot by transport of Na+ from the root to the shoot in external high concentration. We found eight QTLs including three for three traits of the shoots, and five for four traits of the roots at five chromosomal regions, controlled complex physiological traits related to rice salt-tolerance under salt stress. Of these QTLs, the two major QTLs with the very large effect, qSNC-7 for shoot Na+ concentration and qSKC-1 for shoot K+ concentration, explained 48.5% and 40.1% of the total phenotypic variance, respectively. The QTLs detected between the shoots and the roots almost did not share the same map locations, suggesting that the genes controlling the transport of Na+ and K+ between the shoots and the roots may be different.

Antitumor effect of bcl-2 antisense phosphorothioate oligodeoxynucleotides on human renal-cell carcinoma cells in vitro and in mice

BACKGROUND AND PURPOSE

Programmed cell death is a genetically regulated pathway that is altered in many cancers. This process is, in part, regulated by the bcl-2 oncogene. Antisense oligodeoxynucleotides (ODNs) targeted to specific oncogenes have been used with some therapeutic success in animal models of leukemia and melanoma cells and human Hodgkin's lymphoma. We evaluated the effects of antisense ODNs targeted to the bcl-2 oncogene on the proliferation of human renal-cell carcinoma (RCC) cells in vitro and on the growth of human RCC xenografts in BALBc nude (nu/nu) mice.

MATERIALS AND METHODS

Expression bcl-2 mRNA in five RCC cell lines (ACHN, Caki-1, RCZ, RCW, and OS-RC-2) was analyzed by reverse transcriptase-polymerase chain reaction. The effects of phosphorothioated ODNs containing human bcl-2 sense and bcl-2 antisense sequences that were transfected with Lipofectin on the proliferation and viability of cultures of established human RCC cell lines were determined by MTS assay. The expression of Bcl-2 protein in ACHN tumor cells following antisense bcl-2 (AS2) ODN treatment was evaluated by Western blot analysis, and the extent of apoptosis in these cells was determined by fluorescence-activated cell sorter (FACS) analysis. The antitumor activity in ACHN xenografts in nu/nu mice was monitored by measuring differences in tumor weight in treated and control mice.

RESULTS

Expression of bcl-2 mRNA was detected in all five RCC lines. Treatment with antisense bcl-2 ODNs inhibited the growth of all tested RCC cells and decreased Bcl-2 protein expression in ACHN cells. The AS2 antisense ODN complementary to the coding region of bcl-2 mRNA showed a superior antiproliferative effect compared with AS1 ODN complementary to the translation initiation region. Inhibition by antisense bcl-2 ODNs of ACHN cells was dose dependent. The FACS analysis revealed that growth inhibition was associated with the induction of programmed cell death. In vivo, AS2 ODN antitumor activity was noted in locally injected groups.

CONCLUSIONS

Treatment of human RCC with antisense ODNs targeted to bcl-2 inhibits growth and is associated with the induction of programmed cell death. These results suggest therapeutic use of antisense bcl2 in the treatment of RCC.

Relationship between p53 gene mutation and protein expression: clinical significance in transitional cell carcinoma of the bladder

Although the mutated p53 gene has been postulated to induce immunohistochemically-detectable p53 protein, reports regarding the relationship between p53 mutation and p53 protein expression have been contradictory. This study investigated the relationship between p53 mutations and p53 expression and their clinical significance for patients with transitional cell carcinoma of the bladder. Eighty-seven transitional cell carcinoma of the bladder were analyzed by immunohistochemistry (IHC) for p53 nuclear accumulation, and the results compared to mutations detected in the p53 gene evaluated by polymerase chain reaction single-strand conformation polymorphism (SSCP) and DNA sequence analysis. By p53 IHC analysis, positive p53 staining was observed in 50 (57.5%) of the 87 tumors. The specificity of IHC, defined as a percentage of IHC negative (<20%) tumors among tumors without mutation, was 94.6%. Despite the good concordance between p53 mutation and p53 protein expression (p<0.0001), 48.0% (24/50) of the tumors showed p53 overexpression without mutation, and 2 (5.4%) tumors with mutation showed no p53 immunoreactivity. Patients with higher grade (grade 3), stage (stages pT2-4), and p53 mutations had a poorer prognosis by Kaplan-Meier survival analysis. A Cox univariate analysis found that grading (hazard ratio 3.139; p=0.002), staging (hazard ratio 3.832; p=0.0005) and p53 mutation (hazard ratio 2.498; p=0.013) were significant variables in these patients, but no variable was independently associated with an increased survival of bladder carcinoma by multivariate analysis. We found that a 20% cut-off level of p53 overexpression showed the highest correlation with prognosis and p53 mutation, however, p53 overexpression and mutation were not superior to staging as prognostic markers. These data suggest that careful assessment of the TNM staging system remains the most reliable predictive indicator of survival for patients with transitional cell carcinoma of the bladder.

[Study on the packings of affinity chromatography for the separation of urokinase]

Two kinds of affinity chromatographic packings for the separation of urokinase were synthesized by coupling of p-amino benzamidine (p-ABZ) to commercially available sepharose and polyepoxypropyl methacrylate (PEPMA). Then they were applied for separating crude urokinase. It was found that the average recovery of bioactivity on sepharose was higher than that on PEPMA, resulting in 108.3% and 43.4% respectively. The high rigidity of PEPMA permits fast flow of protein solutions and operation by higher-pressure affinity chromatography. The average purification times were 36.9 folds for PEPMA column and nine-folds for Sepharose column. The purification of crude urokinase described in this paper demonstrates that PEPMA column is effective for purifying biological products in a large scale.

Transient inhibition of L929 cell mitosis and locomotion by argon ion laser irradiation

Argon ion laser irradiation of L929 cells transiently inhibits both entry into and passage through mitosis without affecting clonogenic survival. Anaphase mitotic figures virtually disappear from irradiated cell monolayers although prophase + metaphase mitotic figures can still be identified. The total number of mitotic figures does not change significantly and time-lapse video recording shows that cells do not enter mitosis following irradiation. This effect is dependent on light dose within the 900-2700 J/cm2 range and persists for 10-48 h depending on the initial light exposure. Inhibition of cell locomotion and subsequent recovery were observed to occur over a similar time course. The possible contribution of these phenomena must be considered whenever biological systems are exposed to argon ion laser irradiation.

Mechanism of action and spectrum of cell lines sensitive to a doxorubicin-transferrin conjugate

A transferrin-doxorubicin conjugate exhibited greatly increased cytotoxicity relative to unconjugated doxorubicin toward a variety of cultured tumor cell lines. An L929 cell line selected for doxorubicin resistance was as sensitive to the transferrin-doxorubicin conjugate as was the parental unselected line. Quantitative measurements of doxorubicin fluorescence in single L929 cells showed that uptake was similar in amount when cells were exposed to equivalent concentrations of doxorubicin presented either free or as the transferrin-doxorubicin conjugate. However, unconjugated drug fluorescence was distributed in membranes, cytoplasm and nucleus, whereas conjugate fluorescence was confined mainly to the cytoplasmic compartment. In as much as NADPH-dependent free radical formation is a known mechanism of doxorubicin cytotoxicity, localization in the vicinity of NADPH production might facilitate this cytotoxic pathway. Neither cytotoxicity nor uptake of the conjugate quantified by doxorubicin fluorescence was significantly blocked by excess free transferrin, and the conjugate was not concentrated in the plasma membrane at 4 degrees C. These findings suggest that conjugate internalization is not entirely dependent on transferrin receptor binding.

Cefixime absorption kinetics after oral administration to humans

Cefixime (CFX) absorption kinetics after oral administration to humans was studied. Four distinct models, incorporating a delay of absorption and first-order elimination kinetics, i.e. first-order absorption (M1), zero-order absorption (M0), Michaelis-Menten type absorption (MM) and Michaelis-Menten type absorption with 'an absorption window' (MM-delta t) were used to fit concentration data of CFX in 10 Chinese men following an oral dose of 400 mg. r2 and AIC were selected as measures of goodness-of-fit. The results show that the MM-delta t model provided a better fit than the other three models. The kinetic parameters were estimated as follows: Vmax' = 10.80 +/- 3.80 mg.l-1.h-1; K(m)' = 88.31 +/- 2.75 micrograms.ml-1; delta t = 4.75 +/- 0.85 h; T1/2 = 4.20 +/- 0.92 h; Tmax = 5.20 +/- 0.92 h; and Cmax = 6.04 +/- 1.70 mg.l-1.

Mechanism of action and spectrum of cell types susceptible to doxorubicin photochemotherapy

We have shown that, whereas argon ion laser irradiation alone is not cytocidal for L929 cells, it greatly increases the cytotoxicity of intracellular doxorubicin. The present study showed that light enhancement of doxorubicin cytotoxicity was not restricted to stock L929 cells, but could also be demonstrated using L929 cells selected for doxorubicin resistance and several standard cell lines that are relatively resistant to doxorubicin prior to selection. Light-enhanced cytotoxicity resulted in extensive nuclear DNA loss and was strongly inhibited by anoxia. These findings suggest that the mechanism by which light exposure enhances doxorubicin cytotoxicity involves DNA damage by intranuclear generation of reactive oxygen species.

Cloning and characterization of a novel transcriptional repressor of the nicotinic acetylcholine receptor delta-subunit gene

We have identified a negative cis-acting regulatory element in the nicotinic acetylcholine receptor delta-subunit gene's promoter. This element resides within a previously identified 47-base pair activity-dependent enhancer. Proteins that bind this region of DNA were cloned from a lambdagt11 innervated muscle expression library. Two cDNAs (MY1 and MY1a) were isolated that encode members of the Y-box family of transcription factors. MY1/1a RNAs are expressed at relatively high levels in heart, skeletal muscle, testis, glia, and specific regions of the central nervous system. MY1/1a are nuclear proteins that bind specifically to the coding strand of the 47-base pair enhancer and suppress delta-promoter activity in a sequence-specific manner. These results suggest a novel mechanism of repression by MY1/1a, which may contribute to the low level expression of the delta-subunit gene in innervated muscle. Finally, the gene encoding MY1/1a, Yb2, maps to the mid-distal region of mouse chromosome 6.

U1 snRNA variants coexist in Bombyx mori cells

Evidence for at least four U1 snRNA variants were obtained from a U1 cDNA library using U1 snRNA from Bombyx mori BmN cells in culture. Sequence analysis of thirty cDNA clones showed that: (1) the nucleotide changes are in the hairpin structures I, II and III; (2) the majority of the base changes in stem structures between a posterior silk gland (PSG) U1 RNA and the BmN U1 clones, as well as among the BmN U1 clones, are compensatory; (3) although the base differences between PSG U1 and BmN U1 clones, and among the BmN U1 clones, are not the same, they are located in similar positions in moderately conserved sites, frequently at the bases of loops; (4) when comparing the PSG U1 with the BmN U1 clones, twelve out of nineteen stem differences generate stronger pairing resulting in a more stable hairpin II in the BmN U1 clones; and (5) the Sm and 70K proteins binding site sequences are highly conserved among these U1 clones. Although a comparison of sequences changes associated with U1 isoforms from different species indicate that there are no common base changes with the B. mori U1 clones reported here, similarities in the multitude and location of base differences in hairpins I, II and III are observed in mouse and/or Xenopus. It is possible that U1 variants like the ones reported here play a role in alternative pre-mRNA splicing by way of different RNA-protein factor interactions.

The amylose content in rice endosperm is related to the post-transcriptional regulation of the waxy gene

The waxy (Wx) gene of rice encodes a granule-bound starch synthase (GBSS = waxy protein) required for the synthesis of amylose in endosperm. An analysis of Wx transcripts, Wx protein, and amylose content of 31 rice cultivars revealed that endosperm amylose and Wx protein contents are correlated with the ability of the cultivar to excise intron I from the leader sequence of the Wx transcript. Cultivars with high endosperm amylose content (group I) contain high levels of amylose, Wx protein, and the mature 2.3 kb Wx mRNA. Cultivars with intermediate amylose content (group II) produce substantial amounts of a large 3.3 kb Wx pre-mRNA, with intron I still present, in addition to the mature Wx mRNA, and intermediate levels of Wx protein. Glutinous rice (group III cultivars) contains no amylose, no Wx protein, and no mature Wx mRNA; only the incompletely spliced 3.3 kb Wx pre-mRNA is present in group III cultivars. Based on these results, it is hypothesized that the amylose content of rice endosperm is regulated at the level of Wx transcript processing, and, more specifically, at the stage of intron I excision from the Wx pre-mRNA.

Photodynamic enhancement of doxorubicin cytotoxicity

Argon ion laser irradiation at 514.1 nm and 488 nm dramatically increased doxorubicin cytotoxicity in an L929 cell clonogenic survival assay. The cytotoxicity was dependent on both the drug concentration and the total light energy delivered such that at 5 micrograms doxorubicin/ml and 800 J/cm2, cytotoxicity was enhanced by a factor of > 10(4) relative to that achieved with drug alone. Irradiation times in excess of 2 min and power densities in excess of 100 J/cm2 were required to produce the effect. Beyond this 2-min limit, cytotoxicity was not related to the duration of exposure if the total energy delivered was held constant. The ability of catalase and superoxide dismutase to abolish completely the increase in cytotoxicity produced by laser irradiation suggests that the cytotoxic mechanism may depend on the generation of active oxygen species by the photodynamically excited drug.

The epidermal growth factor/cAMP-inducible ectoCa(2+)-ATPase of human hepatoma Li-7A cells is similar to rat liver ectoATPase/hepatocyte cell adhesion molecule (cell-CAM 105)

Human hepatoma Li-7A cells exhibit two cell surface ATPase (ectoATPase) activities distinguishable by their different biochemical properties. The activity of the minor ectoATPase, ectoCa(2+)-ATPase, is enhanced severalfold when Li-7A cells are treated simultaneously by epidermal growth factor (EGF) and cAMP elevating agents (Knowles, A. F., 1990, Arch. Biochem. Biophys. 283, 114-119). Here we report that the human ectoCa(2+)-ATPase is biochemically similar to the major rat hepatocyte ectoATPase/cell adhesion molecule (cell-CAM 105) with respect to response to divalent ions and sulfhydryl reagents. Furthermore, the binding of rat liver ectoATPase antibody increased markedly in EGF/cholera toxin/hydrocortisone-treated Li-7A cells compared to untreated cells. Western blot analysis revealed cross-reactivity of the antibody with a 125-kDa protein. Partial purification of ectoCa(2+)-ATPase from EGF/cholera toxin/hydrocortisone-treated Li-7A cells confirmed that enrichment of the 125-kDa protein correlated with an increase in ATPase activity. We conclude that EGF and increased levels of cAMP lead to increased synthesis of the ectoCa(2+)-ATPase in Li-7A cells. The present demonstration of similarity between the ectoCa(2+)-ATPase and a rat liver cell adhesion molecule, cell-CAM 105, contributes significantly to an understanding of the implication of down-regulation of ectoCa(2+)-ATPase during hepatocyte-hepatoma transformation.

Glycemia and exercise training alter glucose transport and GLUT4 in the Zucker rat

The purpose of this study was to determine the effects of chronic hyperglycemia and/or exercise training on the muscle concentration of the insulin-responsive glucose transporter protein, GLUT4, and on maximally insulin-stimulated hindlimb muscle glucose transport. Five-wk-old lean and obese Zucker rats were randomly assigned to sham-operated control (CTL) or 90% pancreatectomized (PX) groups. Obese-PX animals were further randomized into sedentary or exercise trained groups (15-wk treadmill running for 2 h.d-1, 5 d.wk-1, 15% grade, at 15-18 m.min-1). Muscle GLUT4 protein content and maximally insulin-stimulated glucose transport were determined in gastrocnemius, plantaris, and soleus muscles. At 20 wk, lean-PX displayed mild fasting hyperglycemia but normal insulin levels. Obese-PX rats had insulin levels similar to lean-CTL rats but had severe hyperglycemia. Hyperglycemia in lean-PX was associated with a 28% decrease in maximal glucose transport and a 65% decrease in muscle GLUT4 (P < 0.05) compared with lean-CTL. In obese-PX, maximal glucose transport was not affected, but muscle GLUT4 was reduced by 62% (P < 0.05) compared to obese-CTL. Exercise training obese-PX reduced hyperglycemia, increased maximal glucose transport by 45%, and increased muscle GLUT4 by > 2-fold (P < 0.05) compared with obese-CTL. Thus, hyperglycemia associated with PX may be an important factor in the reduction of muscle GLUT4 levels in lean and obese rats. The reduced GLUT4 was accompanied by reduced maximal glucose transport in lean but not obese rats. Exercise training reduced hyperglycemia, normalized glucose transport, and increased muscle GLUT4 in obese-PX.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of reduced nicotinamide adenine dinucleotide phosphate in glucose- and temperature-dependent doxorubicin cytotoxicity

The mechanism of doxorubicin resistance induced by glucose deprivation was examined using an L929 cell system. Resistance developed even when the synthesis of glucose-regulated proteins was suppressed by supplementing glucose-deprived cultures with uridine. Resistance was also not correlated with pyruvate availability, with DNA strand breaks, or with intracellular drug or nucleotide levels. However, intracellular concentrations of reduced nicotinamide adenine dinucleotide phosphate (NADPH) decreased to undetectable levels in glucose-deprived cells with or without uridine supplementation. NADPH depletion induced by treating glucose-fed cells with low concentrations of methylene blue afforded the same degree of protection as glucose deprivation, and normal sensitivity could be restored to glucose-deprived cells by adding NADPH to the culture medium. These results suggest that decreased NADPH availability is responsible for the doxorubicin resistance induced by glucose deprivation. Although drug uptake and NADPH production increased with temperature, these effects could not fully account for the > 1000-fold decrease in clonogenic survival observed over the 25 degrees-37 degrees C temperature range. Similarly, manipulation of NADPH levels confirmed a role for drug bioreduction in the cytotoxic mechanism but did not suggest that NADPH availability was rate-limiting for this process at any temperature employed.

Induction by Electric Currents of Ethylene Biosynthesis in Cucumber (Cucumis sativus L.) Fruit

The effects of an electric current on ethylene biosynthesis were investigated in cucumber (Cucumis sativus L.) fruit that were producing almost no ethylene. Direct currents at 0.5 to 3.0 milliamperes induced much ethylene synthesis, with a rapid continuous increase in the rate, which reached a peak within 5 to 6 hours and then decreased. The rate of production was greater with a stronger current. Ethylene production was not observed after the use of a sine-wave alternating current (60 hertz) at 3 milliamperes, the magnitude at which a direct current had the greatest effect. The activity of 1-aminocyclopropane-1-carboxylic acid (ACC) synthase and ethylene forming enzyme (EFE) increased before the rise in ethylene production. ACC synthase and EFE were activated sixfold and fourfold, respectively, by 2 hours. The concentration of ACC increased linearly up to 6 hours and then decreased. Ethylene induction by an electric current was suppressed almost completely by the infiltration of the cucumbers with 5 millimolar aminooxyacetic acid, an inhibitor of ACC synthase, and was also suppressed 70% by 5 millimolar salicylic acid, an inhibitor of EFE. The results indicate that the ethylene induced by the direct current was synthesized via the ACC-ethylene pathway as a result of electrical stress, a new kind of stress to be identified.

Enrichment of biologically active U1 small nuclear RNAs by ion-exchange high-performance liquid chromatography

The use of ion-exchange high-performance liquid chromatography in conjunction with preparative electrophoresis to facilitate the purification of biologically active snRNAs is described. Separation of total nuclear RNA from a Bombyx mori cell line was done with a Bio-Rad MA7 plasmid column in a HRLC 500 system. Individual fractions were subjected to electrophoresis through 14% polyacrylamide gels for identification. High levels of U1 RNA were confirmed by Northern analysis with a human U1 probe. Biological activity of RNAs from the column was demonstrated by their ability to incorporate 32P-AMP at the 3' end. Ion-exchange chromatography provides a rapid, automated method for purifying large amounts of RNAs that can then be utilized in further studies.

The epidemiology of a measles outbreak on a remote offshore island near Taiwan

In September-October 1985, a measles outbreak occurred among elementary school students on a small offshore island near Taiwan. The outbreak began with nosocomial transmission of measles in a hospital emergency room on the main island of Taiwan. Four distinct generations of transmission occurred among elementary school children an their household contacts. Elementary school children were susceptible to measles because they were born after the last major outbreak, but before measles vaccine was locally available. Low immunization rates and low vaccine efficacy contributed to the spread of measles among preschool-age household contacts.

Nucleoside restoration of heat resistance and suppression of glucose-regulated protein synthesis by glucose-deprived L929 cells

Depriving cultured cells of glucose increases glucose-regulated protein synthesis, suppresses heat shock protein synthesis, and increases sensitivity to killing by hyperthermia. The present study shows that supplementation of glucose-free culture medium with uridine or a number of other nucleosides reverses all these effects of glucose deprivation. Uridine is more effective in this regard than equimolar concentrations of glucose, and ribose is relatively ineffective. Uridine does not suppress glucose-regulated protein synthesis that has been induced by glycosylation inhibitors, calcium chelation, or anoxia. We infer from these data that the effects of glucose deprivation may result from inhibition of ribonucleoside synthesis and that ribonucleosides may be directly involved in regulating glucose-regulated protein and heat shock protein synthesis as well as in protecting cells against hyperthermic cytotoxicity.

Sodium bicarbonate ingestion improves performance in interval swimming

In an effort to determine the effects of bicarbonate (NaHCO3) ingestion on exercise performance, ten male college swimmers were studied during five different trials. Each trial consisted of five 91.4 m (100-yd) front crawl swims with a two-minute rest interval between each bout. The trials consisted of two NaHCO3 treatments, two placebo trials and one test with no-drink. One hour before the onset of swimming, the subjects were given 300 ml of citric acid flavored solution containing either 17 mmol of NaCl (placebo) or 2.9 mmol of NaHCO3.kg-1 body weight (experimental), or received no drink (no-drink). Performance times for each 91.4 m swim were recorded. Blood samples were obtained before and one hr after treatment, two min after warmup, and two min after the final 91.4 m sprint. Blood pH, lactate, standard bicarbonate (SBC) and base excess (BE) were measured. No differences were found for performance or the blood measurements between the placebo and no-drink trials. Bicarbonate feedings, on the other hand, produced a significant (P less than 0.05) improvement in performance on the fourth and fifth swimming sprints. Blood lactate, pH, SBC and BE were significantly higher (P less than 0.05) at post-exercise in NaHCO3 treatments. These data are in agreement with previous findings that during repeated bouts of exercise pre-exercise administration of NaHCO3 improves performance, possibly by facilitating the efflux of hydrogen ions from working muscles and thereby delaying the onset of fatigue.