Preoperative diagnostic value of coronary CT angiography in acute Stanford type A aortic dissection involving the coronary arteries.

AIM: To assess the diagnostic value of coronary computed tomography angiography (CCTA) in acute type A aortic dissection (ATAAD) with coronary artery involvement and to evaluate whether CCTA could provide potentially useful information for selecting the surgical method. MATERIALS AND METHODS: Patients with ATAAD treated from January 2019 to December 2020 were reviewed retrospectively. Involvement of the coronary arteries based on CCTA findings were grouped into three major types and five subtypes. Interobserver and intraobserver diagnostic agreement for five subtypes were determined. The patients were divided into the coronary artery bypass grafting (CABG) and non-CABG groups, and the proportions of the five subtypes between the two groups were compared. RESULTS: A total of 95 patients were enrolled in this study. Interobserver and intraobserver diagnostic agreement were both substantial in the left and right coronary arteries. Overall, the proportions of the five subtypes of coronary artery involvement were significantly different between the two groups (p<0.001). The proportion of Type A was elevated in the non-CABG group compared with the CABG group (22.6% versus 71.9%); by contrast, the proportions of Type B1 (35.5% versus 14.1%), Type B2 (19.4% versus 10.9%), Type C1 (6.5% versus 0%), and Type C2 (16.1% versus 3.1%) were elevated in the CABG group. CONCLUSION: CCTA is reliable in evaluating coronary artery involvement by ATAAD. The present retrospective study indicated that CABG may be considered if the intimal flap disrupts the coronary orifice and causes luminal stenosis >50%, particularly Type B, or if an intimal tear occurs in the coronary orifice (Type C), which deserve further validation through prospective studies.

[Expression of chemokine like factor-like myelin and lymphocyte and related proteins for vesicle trafficking and membrane link transmembrane domain-containing protein 2 in rats with varicocele].

OBJECTIVE: To investigate whether chemokine like factor (CKLF)-like myelin and lymphocyte and related proteins for vesicle trafficking and membrane link (MARVEL) transmembrane domain-containing protein 2 (CMTM2) is involved in spermatogenesis in varicocele induced subfertility rats and to discuss the possible mechanisms. METHODS: Forty male SD rats (body weight: 220-330 g, age: 6-7 weeks) were randomly divided into 4 groups: varicocele for 4 weeks, varicocele for 12 weeks, sham operation for 4 weeks and sham operation for 12 weeks, with 10 rats in each group. These rats were introduced by partially ligating left kidney veins for the experimental groups, and the sham surgery groups as controls were executed with exactly the same surgery as in the experimental groups except for the ligation. The rats in control and experimental groups for 4 and 12 weeks were killed after laparotomy at the end of 4 and 12 weeks, respectively, the left testes and epididymis were taken out for counting the sperm, observing the seminiferous tubule change and immunochemistry for CMTM2. The changes included sperm density and motility, the outer diameter and inner diameter change and the changes of epithelium and the CMTM2 expression in immunochemistry. RESULTS: Compared with the control groups, the sperm density [(63.9±7.1)×10(6)/mL vs.(74.3±5.0)×10(6)/mL] and motility [(58.7%±7.9%) vs.(66.1%±4.3%)] were reduced slightly in group of varicoele for 4 weeks, respectively (t=1.432, 1.563; P=0.076, 0.059, respectively). Varicocele significantly caused a decrease in sperm concentration [(40.5±7.2) ×10(6)/mL vs.(71.1±4.5)×10(6)/mL] and motility [(35.2%±8.5%)vs. (63.4%±4.1%)] at 12 weeks, compared with the related sham groups (t=3.754, 3.933; P=0.004, 0.002, respectively). Additionally, testis CMTM2 exhibited the same disparity, that is, the CMTM2 protein expression in varicocele group was significantly reduced, with the ratio of sham group to varicocele group at the end of 12 weeks 2.3±0.4 (t=1.978; P=0.039). In the evaluation of seminiferous tubules diameter, the external [(198.2±10.2) µm vs. (255.8±12.7) µm, t=2.125, P=0.003] and epithelium diameter [(54.1±1.5) µm vs. (75.5±4.1) µm, t=2.246, P=0.021] were decreased compared with the sham-related groups and previous varicocele groups. In all the varicocele groups, all types of sperm motility decreased compared with the related sham-operated group (P<0.05). CONCLUSION: This study suggests varicocele has a detrimental effect on CMTM2 levels and decreases spermatogonia cell number, seminiferous tubules diameter, and sperm indices. CMTM2 is associated with sperm changes in rats with varicocele, and further studies are needed to study the mechanism.

[Expression of chemokine like factor-like myelin and lymphocyte and related proteins for vesicle trafficking and membrane link transmembrane domain-containing protein 2 in rats with varicocele].

OBJECTIVE: To investigate whether chemokine like factor (CKLF)-like myelin and lymphocyte and related proteins for vesicle trafficking and membrane link (MARVEL) transmembrane domain-containing protein 2 (CMTM2) is involved in spermatogenesis in varicocele induced subfertility rats and to discuss the possible mechanisms. METHODS: Forty male SD rats (body weight: 220-330 g, age: 6-7 weeks) were randomly divided into 4 groups: varicocele for 4 weeks, varicocele for 12 weeks, sham operation for 4 weeks and sham operation for 12 weeks, with 10 rats in each group. These rats were introduced by partially ligating left kidney veins for the experimental groups, and the sham surgery groups as controls were executed with exactly the same surgery as in the experimental groups except for the ligation. The rats in control and experimental groups for 4 and 12 weeks were killed after laparotomy at the end of 4 and 12 weeks, respectively, the left testes and epididymis were taken out for counting the sperm, observing the seminiferous tubule change and immunochemistry for CMTM2. The changes included sperm density and motility, the outer diameter and inner diameter change and the changes of epithelium and the CMTM2 expression in immunochemistry. RESULTS: Compared with the control groups, the sperm density [(63.9±7.1)×106/mL vs.(74.3±5.0)×106/mL] and motility [(58.7%±7.9%) vs.(66.1%±4.3%)] were reduced slightly in group of varicoele for 4 weeks, respectively (t=1.432, 1.563; P=0.076, 0.059, respectively). Varicocele significantly caused a decrease in sperm concentration [(40.5±7.2) ×106/mL vs.(71.1±4.5)×106/mL] and motility [(35.2%±8.5%)vs. (63.4%±4.1%)] at 12 weeks, compared with the related sham groups (t=3.754, 3.933; P=0.004, 0.002, respectively). Additionally, testis CMTM2 exhibited the same disparity, that is, the CMTM2 protein expression in varicocele group was significantly reduced, with the ratio of sham group to varicocele group at the end of 12 weeks 2.3±0.4 (t=1.978; P=0.039). In the evaluation of seminiferous tubules diameter, the external [(198.2±10.2) µm vs. (255.8±12.7) µm, t=2.125, P=0.003] and epithelium diameter [(54.1±1.5) µm vs. (75.5±4.1) µm, t=2.246, P=0.021] were decreased compared with the sham-related groups and previous varicocele groups. In all the varicocele groups, all types of sperm motility decreased compared with the related sham-operated group (P<0.05). CONCLUSION: This study suggests varicocele has a detrimental effect on CMTM2 levels and decreases spermatogonia cell number, seminiferous tubules diameter, and sperm indices. CMTM2 is associated with sperm changes in rats with varicocele, and further studies are needed to study the mechanism.

[Analysis of metabolic factors and relevance with the grade and stage in patients with renal cell carcinoma].

OBJECTIVE: To investigate the association between metabolic factors, such as obesity, blood pressure, blood glucose, serum lipid profile, and the histopathological characteristics of renal cell carcinoma. METHODS: The medical records of 382 consecutive renal cell carcinoma patients who underwent radical or partial nephrectomy at Peking University People's Hospital from January 2009 to January 2015 were retrospectively reviewed. Metabolic factors were collected from the records, including weight, body mass index, waist circumstance, blood pressure, fasting blood glucose, serum total triglyceride, serum total cholesterol, serum low-density lipoprotein-cholesterol and serum high-density lipoprotein-cholesterol. The patients were divided into different groups according to tumor grade, stage and diameter. Statistics analysis, such as t test, Mann-Whitney U test and Logistic analysis, were performed to investigate the association between metabolic factors and grade, stage and tumor diameter of renal cell carcinoma. RESULTS: A total of 80 (20.94%) of the tumors were classified as high grade disease, 63 (16.49%) were classified as advanced disease and 153 (40.05%) tumor diameter more than 4 cm. The patients in high grade group were found to have lower high-density lipoprotein-cholesterol level than in low grade group (P=0.015), body mass index, total cholesterol and high-density lipoprotein-cholesterol were found to be lower in advanced disease than in localized disease (P=0.022, P=0.005 and P=0.006, respectively), and low-density lipoprotein-cholesterol was found to be lower in larger tumors (P=0.030). Other factors were comparable between the different groups. The results of Logistic analyses showed that, body mass index (OR=0.906, 95%CI: 0.852-0.986, P=0.023) and total cholesterol (OR=0.660, 95%CI: 0.492-0.884, P=0.005) were associated with the tumor stage, high-density lipoprotein- cholesterol level was significantly associated with tumor grade (OR=0.293, 95%CI: 0.108-0.797, P=0.016) and stage (OR=0.204, 95%CI: 0.065-0.635, P=0.006), and low-density lipoprotein-cholesterol level was significantly associated with tumor diameter (OR=0.756, 95%CI: 0.586-0.975, P=0.031). CONCLUSION: The results of our study indicate that metabolic factors, especially obesity and serum lipid profile, are closely related with the histopathological characteristics of renal cell carcinoma.

[Analysis of metabolic factors and relevance with the grade and stage in patients with renal cell carcinoma].

OBJECTIVE: To investigate the association between metabolic factors, such as obesity, blood pressure, blood glucose, serum lipid profile, and the histopathological characteristics of renal cell carcinoma. METHODS: The medical records of 382 consecutive renal cell carcinoma patients who underwent radical or partial nephrectomy at Peking University People's Hospital from January 2009 to January 2015 were retrospectively reviewed. Metabolic factors were collected from the records, including weight, body mass index, waist circumstance, blood pressure, fasting blood glucose, serum total triglyceride, serum total cholesterol, serum low-density lipoprotein-cholesterol and serum high-density lipoprotein-cholesterol. The patients were divided into different groups according to tumor grade, stage and diameter. Statistics analysis, such as t test, Mann-Whitney U test and Logistic analysis, were performed to investigate the association between metabolic factors and grade, stage and tumor diameter of renal cell carcinoma. RESULTS: A total of 80 (20.94%) of the tumors were classified as high grade disease, 63 (16.49%) were classified as advanced disease and 153 (40.05%) tumor diameter more than 4 cm. The patients in high grade group were found to have lower high-density lipoprotein-cholesterol level than in low grade group (P=0.015), body mass index, total cholesterol and high-density lipoprotein-cholesterol were found to be lower in advanced disease than in localized disease (P=0.022, P=0.005 and P=0.006, respectively), and low-density lipoprotein-cholesterol was found to be lower in larger tumors (P=0.030). Other factors were comparable between the different groups. The results of Logistic analyses showed that, body mass index (OR=0.906, 95%CI: 0.852-0.986, P=0.023) and total cholesterol (OR=0.660, 95%CI: 0.492-0.884, P=0.005) were associated with the tumor stage, high-density lipoprotein- cholesterol level was significantly associated with tumor grade (OR=0.293, 95%CI: 0.108-0.797, P=0.016) and stage (OR=0.204, 95%CI: 0.065-0.635, P=0.006), and low-density lipoprotein-cholesterol level was significantly associated with tumor diameter (OR=0.756, 95%CI: 0.586-0.975, P=0.031). CONCLUSION: The results of our study indicate that metabolic factors, especially obesity and serum lipid profile, are closely related with the histopathological characteristics of renal cell carcinoma.

Trade-offs between seed dispersal and dormancy in an amphi-basicarpic cold desert annual.

BACKGROUND AND AIMS: Several studies have demonstrated trade-offs between depth of seed dormancy and dispersal ability for diaspore-dimorphic species. However, relatively little is known about trade-offs between these two life history traits for a species that produces more than two diaspore morphs. The aim of this study was to investigate the relationship between seed dormancy and dispersal in Ceratocarpus arenarius, an amphi-basicarpic cold desert annual that produces a continuum of dispersal unit morphs. METHODS: A comparison was made of dispersal and dormancy breaking/germination responses of dispersal units from ground level (a), the middle of the plant canopy (c) and the top of the plant canopy (f). Various features of the morphology and mass of dispersal units and fruits (utricles) were measured. The role of bracteoles in diaspore dispersal by wind, settlement onto the soil surface and dormancy/germination was determined by comparing responses of intact dispersal units and fruits. Movement of dispersal units by wind and animals, seed after-ripening, germination phenology and the presence of water-soluble germination inhibitors in bracteoles were tested using standard procedures. KEY RESULTS: Dispersal units a, c and f differed in morphology and mass; in the majority of cases, extremes were exhibited by a and f, with c being intermediate. Overall, relative dispersal ability was f > c > a, whereas relative intensity of dormancy was a > c > f. Bracteoles increased dispersal distance by wind, enhanced settlement of diaspores onto the soil surface and mechanically inhibited germination. CONCLUSIONS: The results provide evidence for a model in which there is a continuous inverse-linear relationship between diaspore dispersal ability and depth of dormancy. Thus, dispersal unit heteromorphism of C. arenarius results in a continuum, from no dispersal ability/high dormancy (dispersal unit a) to high dispersal ability/low dormancy (unit f), which may be a bet-hedging strategy in the cold desert environment.

Reproductive parameters in Guizhou snub-nosed monkeys (Rhinopithecus brelichi).

In this study, we present data on reproductive parameters and birth seasonality of Guizhou snub-nosed monkeys (Rhinopithecus brelichi). Our analyses are based on data from a small captive population collected over 15 years and on 5 years of observations of free-ranging snub-nosed monkeys. Captive females (n=4) mature at an age of 70.8+/-6.7 months and reproduce for the first time at 103.4+/-7.5 months. The mean interbirth interval was 38.2+/-4.4 months if the infant survived more than 6 months, which is longer than that in R. roxellana and R. bieti. In the wild and in captivity, births are very seasonal and occur only in a period from the end of March to the end of April. Our data suggest that population growth in Guizhou snub-nosed monkeys is slow compared with the other two Chinese snub-nosed monkey species. The risk of extinction is therefore particularly high in this species, given the small overall population size and slow population recovery potential.

Effects of predispersal insect seed predation on the early life history stages of a rare cold sand-desert legume.

Seed predation by insects is common in seeds of Fabaceae (legume) species with physical dormancy (PY). However, the consequences of insect seed predation on the life history of legumes with PY have been little studied. In the largest genus of seed plants, Astragalus (Fabaceae), only one study has tested the effects of insect predation on germination, and none has tested it directly on seedling survival. Thus, we tested the effects of insect predation on seed germination and seedling growth and survival of Astragalus lehmannianus, a central Asian sand-desert endemic. Under laboratory conditions, seeds lightly predated in the natural habitat of this perennial legume germinated to a much higher percentage than intact seeds, and seedlings from predated and nonpredated seeds survived and grew about equally well. Further, in contrast to our prediction seedlings from predated seeds that germinated "out-of-season" under near-natural conditions in NW China survived over winter. The implication of our results is that individual plants from predated seeds that germinate early (in our case autumn) potentially have a fitness advantage over those from nonpredated seeds, which delay germination until spring of a subsequent year.

Effect of Seed Position on Parental Plant on Proportion of Seeds Produced with Nondeep and Intermediate Physiological Dormancy.

The position in which seeds develop on the parental plant can have an effect on dormancy-break and germination. We tested the hypothesis that the proportion of seeds with intermediate physiological dormancy (PD) produced in the proximal position on a raceme of Isatis violascens plants is higher than that produced in the distal position, and further that this difference is related to temperature during seed development. Plants were watered at 3-day intervals, and silicles and seeds from the proximal (early) and distal (late) positions of racemes on the same plants were collected separately and tested for germination. After 0 and 6 months dry storage at room temperature (afterripening), silicles and seeds were cold stratified for 0-16 weeks and tested for germination. Mean daily maximum and minimum temperatures during development/maturation of the two groups of seeds did not differ. A higher proportion of seeds with the intermediate level than with the nondeep level of PD was produced by silicles in the proximal position than by those in the distal position, while the proportion of seeds with nondeep PD was higher in the distal than in the proximal position of the raceme. The differences were not due only to seed mass. Since temperature and soil moisture conditions were the same during development of the seeds in the raceme, differences in proportion of seeds with intermediate and nondeep PD are attributed to position on parental plant. The ecological consequence of this phenomenon is that it ensures diversity in dormancy-breaking and germination characteristics within a seed cohort, a probable bet-hedging strategy. This is the first demonstration of position effects on level of PD in the offspring.

Effects of germination season on life history traits and on transgenerational plasticity in seed dormancy in a cold desert annual.

The maternal environment can influence the intensity of seed dormancy and thus seasonal germination timing and post-germination life history traits. We tested the hypotheses that germination season influences phenotypic expression of post-germination life history traits in the cold desert annual Isatis violascens and that plants from autumn- and spring-germinating seeds produce different proportions of seeds with nondeep and intermediate physiological dormancy (PD). Seeds were sown in summer and flexibility in various life history traits determined for plants that germinated in autumn and in spring. A higher percentage of spring- than of autumn-germinating plants survived the seedling stage, and all surviving plants reproduced. Number of silicles increased with plant size (autumn- > spring-germinating plants), whereas percent dry mass allocated to reproduction was higher in spring- than in autumn-germinating plants. Autumn-germinating plants produced proportionally more seeds with intermediate PD than spring-germinating plants, while spring-germinating plants produced proportionally more seeds with nondeep PD than autumn-germinating plants. Flexibility throughout the life history and transgenerational plasticity in seed dormancy are adaptations of I. violascens to its desert habitat. Our study is the first to demonstrate that autumn- and spring-germinating plants in a species population differ in proportion of seeds produced with different levels of PD.

Seed Germination Ecology of the Cold Desert Annual Isatis violascens (Brassicaceae): Two Levels of Physiological Dormancy and Role of the Pericarp.

The occurrence of various species of Brassicaceae with indehiscent fruits in the cold deserts of NW China suggests that there are adaptive advantages of this trait. We hypothesized that the pericarp of the single-seeded silicles of Isatis violascens restricts embryo expansion and thus prevents germination for 1 or more years. Thus, our aim was to investigate the role of the pericarp in seed dormancy and germination of this species. The effects of afterripening, treatment with gibberellic acid (GA3) and cold stratification on seed dormancy-break were tested using intact silicles and isolated seeds, and germination phenology was monitored in an experimental garden. The pericarp has a role in mechanically inhibiting germination of fresh seeds and promotes germination of nondormant seeds, but it does not facilitate formation of a persistent seed bank. Seeds in silicles in watered soil began to germinate earlier in autumn and germinated to higher percentages than isolated seeds. Sixty-two percent of seeds in the buried silicles germinated by the end of the first spring, and only 3% remained nongerminated and viable. Twenty to twenty-five percent of the seeds have nondeep physiological dormancy (PD) and 75-80% intermediate PD. Seeds with nondeep PD afterripen in summer and germinate inside the silicles in autumn if the soil is moist. Afterripening during summer significantly decreased the amount of cold stratification required to break intermediate PD. The presence of both nondeep and intermediate PD in the seed cohort may be a bet-hedging strategy.

Protective effects of nitroglycerin-induced preconditioning mediated by calcitonin gene-related peptide in rat small intestine.

Previous studies of myocardium have shown that ischemic preconditioning could be mimicked by nitroglycerin through stimulating the release of calcitonin gene-related peptide (CGRP). The present study examined whether nitroglycerin could also provide a preconditioning stimulus in the peripheral vascular bed (the anse intestinalis of rat), and whether endogenous CGRP is involved in this process. The model of in situ perfusion was prepared with rat small intestine. One hour of ischemia and 15 min of reperfusion caused a significant impairment of intestinal morphology and an increase in the release of both lactate dehydrogenase and malondialdehyde. Pretreatment with nitroglycerin, 10(-7), 3 x 10(-7), 10(-6) M for 5 min produced a significant improvement of intestinal tissue morphology and a decrease in the release of both lactate dehydrogenase and malondialdehyde. However, the protection afforded by nitroglycerin was abolished by CGRP-(8-37), a selective CGRP acceptor antagonist. Pretreatment with capsaicin, which specifically depletes the transmitter content of sensory nerves, also abolished the protection by nitroglycerin. In addition, the content of CGRP-like immunoreactivity in the effluent was increased during nitroglycerin perfusion. On the other hand, the results from the in vivo experiment showed that nitroglycerin (i.v. 0.13 mg/kg) injected 5 min before prolonged ischemia could provide significant protection against the injury caused by 30-min ischemia and 1-h reperfusion in the rat small intestine, but would also cause a significant increase in the levels of CGRP in the plasma. All these findings suggest that nitroglycerin-induced preconditioning is related to stimulation of CGRP release in the rat small intestine.

Role of endogenous opioid peptides in protection of ischemic preconditioning in rat small intestine.

This study investigated the protective effects of ischemic preconditioning on intestinal ischemic injury and the role of endogenous opioid peptides (EOP) in these effects. Ischemia-reperfusion (I/R) induced by 30-min of ischemia and 60-min of reperfusion significantly increased the levels of malondialdehyde (MDA) and lactate dehydrogenase (LDH) and resulted in serious intestinal edema (wet weight/dry weight). The ischemic preconditioning (PC) elicited by three 8-min occlusion periods interspersed with 10-min reperfusion markedly attenuated intestinal injury caused by ischemia-reperfusion. Pretreatment with morphine (300 microg x kg(-1), i.v.) 10-min before ischemia and reperfusion mimicked the protection produced by PC. Naloxone (3 mg x kg(-1), i.v.) abolished the protection of morphine-induced preconditioning and ischemic preconditioning in rat intestine. However, there were no changes between naloxone alone and control groups. Treatment with naloxone before ischemia-reperfusion had no effect on animals compared with the I/R group. In addition, we also measured the content of endogenous opioid peptides (Leu-enkephalin) in the effluent which was collected before and during preconditioning. It was shown that the release of leu-enkephalin was markedly increased during preconditioning. These results suggested that EOP might play an important role in PC in rat small intestine.

Activated polymorphonuclear leukocytes induce cardiomyocyte apoptosis and the protective effects of carvedilol.

Previous studies have shown that ischemia and reperfusion are potent stimuli for eliciting cardiomyocyte apoptosis, and that polymorphonuclear leukocytes (PMNs) are involved in the development of myocardial injury induced by ischemia and reperfusion. The present study examined whether PMN could directly induce cardiomyocyte apoptosis and, if so, it possible signal transduction pathways. In addition, we also investigated the effects of carvedilol, a potent antioxidant, on PMN-induced apoptosis. Cultured primary neonatal rat cardiomyocytes were exposed to PAF-activated PMNs at concentrations of 10(5), 3 x 10(5) and 10(6) cells/well for 48 h. Multiple detecting techniques, including electron microscopy, DNA gel electrophoresis. TUNEL assay and flow cytometry were used to identify myocyte apoptosis. All of these techniques demonstrated that activated PMNs directly induced cardiomyocyte apoptosis in a concentration-dependent manner, while unactivated PMNs showed no such effect. Activated PMN-induced apoptosis was partially inhibited by SB203580, a specific inhibitor of the p38-MAPK signaling system. Carvedilol (at a dose range of 1-10 mumol/l) significantly prevented activated PMN-induced cardiomyocyte apoptosis. These results suggest that PMNs, when activated, directly induce cardiomyocyte apoptosis and that the p38-MAPK signaling pathway might be involved in this process. Carvedilol may prevent PMN-induced apoptosis possibly because of its antioxidant properties.

[The study of transesophageal ultrasonography in assessing operability of the advanced esophageal carcinoma].

Abstract sixty-one advanced esophageal carcinoma patients were examined by transesophageal ultrasonography (TEUS), in which fifty three squamous cell carcinomas and eight adenocarcinomas were diagnosed by pathology. There were clearly demarcated spaces between the tumours and the important adjacent structures in the local resectable fourty-two of fourty-eight cases. On the contrary, the ultrasonic images of the non-resectable ten cases showed the unclear demarcation between the tumours and thoracic aorta, pulmonary vein, pericardium and so on in several images. The study discovered the interruption of the regional echo of the normal aortic wall where the hypoechoic area took instead of aortic wall echo in several patients. The squeezed signs of the tumours to the aortic wall might be shown. These signs demonstrated tumour invading severely the aorta. Three cases of metastasis of liver were not operated on. Six patients failed to predicted accurately because the stenosis could not be passed with TEUS. The accurate a assessing the operability of those cases with TEUS was 85.2%. So TEUS is a useful, simply, reliable method for the assessing the operability of esophageal carcinoma.

Germination season and watering regime, but not seed morph, affect life history traits in a cold desert diaspore-heteromorphic annual.

Seed morph, abiotic conditions and time of germination can affect plant fitness, but few studies have tested their combined effects on plasticity of plant life history traits. Thus, we tested the hypothesis that seed morph, germination season and watering regime influence phenotypic expression of post-germination life history traits in the diaspore-heteromorphic cold desert winter annual/spring ephemeral Diptychocarpus strictus. The two seed morphs were sown in watered and non-watered plots in late summer, and plants derived from them were watered or not-watered throughout the study. Seed morph did not affect phenology, growth and morphology, survival, dry mass accumulation and allocation or silique and seed production. Seeds in watered plots germinated in autumn (AW) and spring (SW) but only in spring for non-watered plots (SNW). A high percentage of AW, SW and SNW plants survived and reproduced, but flowering date and flowering period of autumn- vs. spring-germinated plants differed. Dry mass also differed with germination season/watering regime (AW > SW > SNW). Number of siliques and seeds increased with plant size (AW > SW > SNW), whereas percent dry mass allocated to reproduction was higher in small plants: SNW > SW > AW. Thus, although seed morph did not affect the expression of life history traits, germination season and watering regime significantly affected phenology, plant size and accumulation and allocation of biomass to reproduction. Flexibility throughout the life cycle of D. strictus is an adaptation to the variation in timing and amount of rainfall in its cold desert habitat.

Functional and molecular analysis of D-serine transport in retinal Müller cells.

D-serine, an endogenous co-agonist of NMDA receptors in vertebrate retina, may modulate glutamate sensitivity of retinal neurons. This study determined at the functional and molecular level the transport process responsible for D-serine in retinal Müller cells. RT-PCR and immunoblotting showed that serine racemase (SR), the synthesizing enzyme for D-serine, is expressed in the rMC-1 Müller cell line and primary cultures of mouse Müller cells (1 degrees MCs). The relative contributions of different amino acid transport systems to d-serine uptake were determined based on differential substrate specificities and ion dependencies. D-serine uptake was obligatorily dependent on Na+, eliminating Na+-independent transporters (asc-1 and system L) for D-serine in Müller cells. The Na+:substrate stoichiometry for the transport process was 1:1. D-serine transport was inhibited by alanine, serine, cysteine, glutamine, and asparagine, but not anionic amino acids or cationic amino acids, suggesting that D-serine transport in Müller cells occurs via ASCT2 rather than ASCT1 or ATB0,+. The expression of mRNAs specific for ASCT1, ASCT2, and ATB0,+ was analyzed by RT-PCR confirming the expression of ASCT2 (and ASCT1) mRNA, but not ATB0,+, in Müller cells. Immunoblotting detected ASCT2 in neural retina and in 1 degrees MCs; immunohistochemistry confirmed these data in retinal sections and in cultures of 1 degrees MCs. The efflux of D-serine via ASCT2 by ASCT2 substrates was demonstrable using the Xenopus laevis oocyte heterologous expression system. These data provide the first molecular evidence for SR and ASCT2 expression in a Müller cell line and in 1 degrees MCs and suggest that D-serine, synthesized in Müller cells by SR, is effluxed via ASCT2 to regulate NMDA receptors in adjacent neurons.

Expression of the cystine-glutamate exchanger (xc-) in retinal ganglion cells and regulation by nitric oxide and oxidative stress.

The cystine-glutamate exchanger, system x(c)(-), mediates the Na(+)-independent exchange of cystine into cells, coupled to the efflux of intracellular glutamate. System x(c)(-) plays a critical role in glutathione homeostasis. Early studies of brain suggested that system x(c)(-) was present primarily in astrocytes but not neurons. More recent work indicates that certain brain neurons have an active system x(c)(-). In the retina, system x(c)(-) has been demonstrated in Müller and retinal pigment epithelial cells. We have recently suggested that two protein components of system x(c)(-), xCT and 4F2hc, are present in ganglion cells of the intact retina. Here, we have used (1) molecular and immunohistochemical assays to determine whether system x(c)(-) is present in primary ganglion cells isolated from neonatal mouse retinas and (2) functional assays to determine whether its activity is regulated by oxidative stress in a retinal ganglion cell line (RGC-5). Primary mouse ganglion cells and RGC-5 cells express xCT and 4F2hc. RGC-5 cells take up [(3)H]glutamate in the absence of Na(+), and this uptake is blocked by known substrates of system x(c)(-) (glutamate, cysteine, cystine, quisqualic acid). Treatment of RGC-5 cells with NO and reactive oxygen species donors leads to increased activity of system x(c)(-) associated with an increase in the maximal velocity of the transporter with no significant change in the substrate affinity. This is the first report of system x(c)(-) in primary retinal ganglion cells and RGC-5 cells. Oxidative stress upregulates this transport system in RGC-5 cells, and the process is associated with an increase in xCT mRNA and protein but no change in 4F2hc mRNA or protein.