新疆桃对4种主要根结线虫的抗性评价

为探明新疆桃抗根结线虫的种质资源价值,以实生钵苗为试材,采用人工接种2龄幼虫的方法,研究了新疆桃对花生根结线虫、北方根结线虫、南方根结线虫和爪哇根结线虫的抗性。结果表明:新疆桃高抗上述4种根结线虫,其实生群体内存在显著的抗性分离现象,对4种根结线虫的抗性均分离为免疫和高抗2种类型,侵入高抗型植株根系内的4种根结线虫的发育受到强烈抑制,以致完全无法产卵繁殖;新疆桃对花生根结线虫、北方根结线虫、南方根结线虫和爪哇根结线虫免疫株率分别为26%、20%、26%、12%。新疆桃是优异的抗根结线虫种质资源。     

根结线虫病害的发生与土壤微生物群落的关系研究进展

通过对根结线虫病害的发生与土壤微生物群落之间的关系进行介绍,从根际微生物对根结线虫的影响、根结线虫对土壤微生物的作用、根际微生物区系分析方法及根结线虫生防资源4个方面进行了综述,探讨了土壤微生物的变化影响根结线虫病害发生的程度,通过可持续性生物防治手段减轻该虫害的发生。     

宁夏永宁葡萄育苗圃根结线虫鉴定

对宁夏永宁县葡萄育苗圃中15个葡萄品种的根结线虫进行形态学和分子生物学鉴定。结果表明:宁夏永宁县葡萄育苗圃根结线虫病危害严重,不同葡萄品种的苗木感病症状表现不同。根据根结线虫雌虫和2龄幼虫的形态特征及雌虫会阴花纹,初步鉴定出该地区葡萄根结线虫的种类是南方根结线虫(Meloidogyne incognita)和花生根结线虫(M.arenaria)。利用根结线虫线粒体DNA(mtDNA)通用引物(C2F3/1108)及序列特异性扩增区(SCAR)特异性引物(MI-F/MI-R和Far F/Far R)对葡萄根结线虫的种类再次鉴定,鉴定结果与形态学鉴定结果一致。另外发现不同葡萄品种上根结线虫的种类与数量存在差异,南方根结线虫(M. incognita)占根结线虫群体的88.57%,为优势种群。     

葡萄根结线虫防治妙招

根结线虫以2龄幼虫侵入葡萄幼嫩根尖端组织，在吸收根或生长根上形成根结，侵染严重时根系几乎无吸收根或很少，地上部生长缓慢，树势衰弱，表现矮小、黄化、萎蔫、果实小等。在我国多数葡萄产区均有发生，砂壤土尤重。     

福建柑桔根结线虫种类及其防治研究

福建省寄生柑桔的根结线虫已鉴定出５个种：柑桔根结线虫、闽南根结线虫、花生根结线虫、苹果根结线虫和短小根结线虫。１０％益舒宝颗粒剂对柑桔根结线虫有良好的防治效果。不同砧木对根结线虫的抗性有差异，枳高度感病，酸橙和红桔较抗病。     

24份葡萄种质抗根结线虫特性的田间自然鉴定

用两种抗性鉴定标准分别对田间的20份葡萄砧木和4份鲜食葡萄品种对葡萄根结线虫的抗性进行了鉴定。结果表明,欧亚种葡萄和欧美杂交种葡萄抗性最低,山平氏葡萄表现为免疫,河岸葡萄表现比较复杂,从中等到免疫都有;河岸葡萄和西班牙葡萄与其他种杂交的后代对根结线虫也表现出较好的抗性。     

福建柑桔结线虫种类及其防治研究

福建寄生柑桔的根结线虫已鉴定出５个种：柑桔根结线虫、闽南根结线虫、花生根结线虫、苹果根结线虫和短小根结线虫。１０％益郐宝颗粒剂对柑桔根结线虫有良好的防治效果。不同贴木对根结线虫的抗性有差异，枳高度感病，酸橙和红桔较抗病。     

杨梅根结线虫病研究

杨梅根结线虫病是一种新发现的杨梅病害，病原线虫为爪哇根结线虫，南方根结线虫和北方根结线虫。爪哇根结线虫为优势种。病害的影响因素有果树品种，种植方式和土壤ｐＨ值。呋喃丹对病害个有防治效果。调节土壤ｐＨ值和用客土改良土壤可以减缓病害和促进果树生长。     

丛枝菌根真菌与葡萄南方根结线虫的相互作用及其对寄主的影响

 在温室盆栽条件下对‘巨峰’葡萄扦插苗接种丛枝菌根(AM) 真菌(Glomus versiforme Berch、Gigaspora margarita Becker & Hall 及Glomus mosseae Nicolson & Gedermann) 和南方根结线虫(Meloidogyne incognita) 。结果表明, 供试AM真菌能不同程度地抑制南方根结线虫病害的发生发展, 降低根围土壤中二龄幼虫数量、卵块直径、平均每个卵块的卵量及平均每克葡萄根系上的卵量, 先接种AM真菌后接种南方根结线虫的处理比同时接种二者抑制线虫病害的效果更好。接种AM真菌可提高葡萄植株光合速率, 增加植株高度、茎粗、叶面积、地上部干样质量和地下部干样质量, 这在一定程度上补偿了由于线虫所造成的损害。此外, 接种南方根结线虫降低了G. mosseae 的根内泡囊和入侵点数量、G. versiforme 及Gi . margarita的侵染率;但增加了G. versiforme 及Gi . margarita 的根内泡囊数及入侵点数。因此, 对每一种AM真菌—植物—线虫组合关系不可能作出统一的概括。     

根际促生菌防治蔬菜根结线虫的研究

从蔬菜根结线虫生物防治的研究现状,PGPR(根际促生菌)防治蔬菜根结线虫研究的国内外现状及相关机理、发展趋势等方面进行论述,为利用PGPR防治蔬菜根结线虫和进行抗线虫育种提供参考。     

Effects of atorvastatin on atrial electrical remodeling in a rabbit model of chronic atrial fibrillation

AIM: To evaluate the effects of atorvastatin (ATO) on atrial electrical remodeling in a rabbit mo-del of chronic atrial fibrillation (AF) produced by 3 weeks of rapid atrial pacing (RAP). METHODS: The sternotomy was performed and the pacing and testing electrodes were fixed to the left atria of 24 New Zealand white rabbits. The animals were randomly divided into 3 groups. The rabbits in model group and ATO group were subjected to RAP for 3 weeks, and then were treated with placebo and ATO (2.5 mg·kg^-1·d^-1), respectively. The rabbits in sham group did not receive RAP and drugs. Electrophysiological examination was performed to test heart rate, P-wave duration, atrial effective refractory period (AERP) and AF inducibility. The protein expression levels of Cav1.2, Kv4.3 and myeloperoxidase (MPO) were detected by Western blot. RESULTS: Sustained AF was induced in 5 and 4 rabbilts in model group and atorvastatin group and no rabbits in sham group was found. After 3 weeks of RAP, compared with sham group, heart rate and P-wave duration were increased and AERP was shortened in model group and ATO group (P<0.05). Compared with model group, AERP was increased in ATO group (P<0.05), while heart rate and P-wave duration had no difference between these 2 groups. Compared with sham group, the protein levels of Cav1.2 and Kv4.3 were decreased, and protein level of MPO was increased in model group and ATO group (P<0.05). Compared with model group, Cav1.2 was increased and MPO was decreased in ATO group (P<0.05), while Kv4.3 had no difference between these 2 groups. CONCLUSION: Atorvastatin suppresses the down-regulation of atrial Cav1.2 protein level and the shortening of AERP, thus preventing atrial electrical remodeling in a rabbit model of chronic AF. The effect of atrovastatin on reducing atrial MPO level may be the potential mechanism.     

Establishment of a rabbit chronic atrial fibrillation model with long-term rapid atrial stimulation

AIM: The aim of this study was to investigate the possibility of establishing a chronic atrial fibrillation model with long-term rapid atrial stimulation (1 000 bpm), which was performed in rabbits in vivo. METHODS: 20 rabbits were randomly divided into 2 groups: 1) control group (n=10): pacemaker was implanted but no pacing; 2) experimental group (n=10): a left intercostal thoracotomy was performed and the pericardium was opened to expose the heart and a steel-wire pacing electrode was fixed on the epicardium of the left atria in 10 rabbits. Then the rapid pulse generator was implanted subcutaneously in the left abdominal region and rapid atrial pacing (1 000 beats/min) was initiated and continued for 30 days. Electrocardiogram (ECG) was monitored and recorded on day 1, 3, 5, 7, 14, 21 and 30. The atrial effective refractory period (AERP) was measured before pacing and at the time of fibrillation. RESULTS: On day 14, atrial fibrillation was developed in 8 rabbits (80%) and sustained at least till to day 30 (P＜0.01). There was no atrial fibrillation occurred in control group. The ventricular rate of atrial fibrillation was fast initially (P＜0.05) and decreased gradually later (P＜0.05). The AERP was shortened and the rate adaptation of AERP was lost when atrial fibrillation occurred. CONCLUSION: Long-term rapid left atria stimulating is an effective method in the establishment of a chronic atrial fibrillation model in rabbits.     

Non-contact mapping and frequency analysis of vagal-mediated atrial fibrillation

AIM: To explore the mechanism of the initiation and maintenance of vagal-mediated atrial fibrillation (AF) by non-contact mapping and frequency analysis of vagal-mediated atrial fibrillation in canine.METHODS: Atrial effective refractory period (AERP) and dispersion of AERP were measured in 8 canine during baseline and bilateral cervical vagal nerve stimulation (CVNS). Left atrium (LA) and right atrium (RA) electrical activity of AF was assessed by non-contact mapping and frequency analysis.RESULTS: Compared with baseline, CVNS attenuated left and right AERP, but only increased the dispersion of left AERP. During CVNS, AF was easily induced and maintained, repetitive organized activations rotated around a preferential route were only found in the LA, and dominant frequencies (DFs) from LA were higher than those of the RA ［(12.5±1.5)Hz vs (9.3±1.2)Hz, P<0.01］. After the cessation of CVNS, DFs of AF decreased in the LA and RA ［(9.2±0.5)Hz vs (8.5±0.6)Hz, P>0.05］, and AF was spontaneously terminated.CONCLUSION: The change of electrophysiological character, difference of activation pattern, and frequency gradient between the LA and RA suggest that the initiation and maintenance of vagal-mediated AF dependent on the LA.     

Effect of changing left ventricular afterload and isolated perfused rabbit heart on ventricular refractory period measured by subthreshold conditioning train stimulation

AIM: To study the effect of changing left ventricular afterload and isolated perfused rabbit heart on ventricular refractory period measured by subthreshold conditioning train stimulation (S_t). METHODS: Ventricular refractory period strength-interval relation was measured by S_t method under the condition of changing left ventricular afterload and eliminating action of nervous and body fluid. RESULTS: Reducing left ventricular afterload pro- longed ventricular refractory period measured by S_t method (P＜0.05, P＜0.01). and S_t (200 Hz,100 ms) and S_t (50 ms,100 Hz) caused maximal prolongation of ventricular refractory period (P＜0.05, P＜0.01). CONCLUSION: Changing left ventricular afterload and eliminating action of nervous and body fluid could cause alteration of characteristic of ventricular refractory period strength-interval relation measured by S_t method.     

Effect of high-rate left atrial pacing on atrial remodeling and functions of sinoatrial node and atrioventricular node in dogs

AIM: To determine whether sinoatrial node (SAN) and atrioventricular node (AVN) undergo functional remodeling during atrial fibrillation (AF). METHODS: The Beagle dogs were randomized into pacing group (n=9) and control group (n=6). In open-chest dogs, the electrode catheters were sutured at left atria for pacing and data recording. SAN and AVN conductive properties were studied. The dogs in pacing group underwent 4 weeks of high-rate left atrial pacing (400 min-1). The dogs in control group were not subject to pacing. RESULTS: The animal model of chronic AF was successfully established by pacing the left atrium at 400 min-1 in the dogs. Two of those animals were recorded with spontaneous AF at the end of 2 weeks, and the induction rate of AF reached 100% following 4 weeks of pacing. The incidences of paroxysmal AF and permanent AF were significantly increased by pacing compared to control group. After 4 weeks of pacing, atrial effective refractory periods (AERP) at various at pacing cycle lengths (PCL; 250 ms, 300 ms and 350 ms) were all statistically shorter than those in control group. Compared with control group, a longer AVN Wenckebach point ［(294.44±26.06)min-1 vs (328.33±24.01)min-1,P<0.05］ and longer atrioventricular node effective refractory period (AVERP) (P<0.01) in pacing group were observed. The sinus node recovery time (SNRT) and corrected SNRT both showed significant increases. No significant change of P-wave and PA interval between the two groups was found. The left atrial dimensions (anteroposterior, superoinferior and left-right diameters) and the right atrial superoinferior diameter were measured to be significantly increased after 2 weeks of pacing. CONCLUSION: The animal model of left atrium pacing can induce AF occurrence with a higher incidence. The characteristic electrophysiological indexes about atria, AVN and SAN were observed during AF in the canine model, indicating that electrical and structural remodeling accompanies with AVN and SAN remodeling during AF.     

Effect of spironolactone on hyperthyroxine-induced atrial fibrillation and atrial remodeling in rabbits

AIM: To detect the effect of spironolactone on hyperthyroxine-induced atrial remodeling. METHODS: New Zealand rabbits were divided into control group (C), hyperthyroxine group (H) and spironolactone group (S). Thyroxin was given to the rabbits in group H and group S by intraperitoneal injection for 4 weeks, and then spironolactone was given in group S by gavage for 2 weeks. Atrial fibrillation (AF) was induced by "burst" stimulation after administration. The inducing rate of AF and atrial effective refractory period (AERP) were tested by intra-cardiac electrophysiologic instrument. The expression of AF-related Ca²⁺ channel (Cav1.2), K⁺ channels (Kv1.5 and Kv4.3) and connexins (Cx40 and Cx43) at mRNA and protein levels was detected by real-time PCR, immunohistochemistry and Western blot. RESULTS: Spironolactone reduced the inducing rate of AF. No significant difference of AERP between group H and group S was observed (CONCLUSION: Spironolactone attenuates the hyperthyroxine-induced atrial remodeling in rabbits, and reduces the susceptibility of the myocardium to AF.     

Effect of streptomycin on electrophysiological changes caused by rising of left ventricular afterload in rabbits

AIM: The aim of this study was to study the changes of rabbit heart electrophysiological properties caused by increasing left ventricular afterload, and to assess the effects of streptomycin or verapamil on these changes. METHODS: The rabbit heart preparation in situ was used, and the afterload of left ventricle was increased by clipping in part the root of ascending aorta. The changes of heart electrophysiological parameters including relative refractory period (RRP), effective refractory period (ERP), monophasic action potential duration (MAPD₉₀) and ventricular fibrillation threshold(VFT) were observed before and after altering the afterload of left ventricle and were compared in the absence and presence of streptomycin or verapamil. RESULTS: The rising of left ventricular afterload led to shortening of RRP, ERP and MAPD₉₀, and to descent of VFT (P＜0.01). Streptomycin inhibited these changes of heart electrophysiological parameters caused by elevation of left ventricular afterload. In contrast, verapamil had no effects on the afterload-related changes of RRP, ERP and MAPD₉₀ (P＞0.05) except increasing of VFT (P＜0.01). CONCLUSION: The electrophysilogical effect of streptomycin appears consistent with inhibition of stretch-activated ion channels, suggesting that the stretch-activated ion channels might be involved in the afterload-related changes of heart electrophysiological properties.     

Effects of cardiac contractility modulation applied to different locations of heart on cardiac functions in rabbits with heart failure

AIM: To investigate the effects of cardiac contractility modulation (CCM) applied to different locations of the heart on cardiac functions and cardiac dys-synchrony in the rabbits with chronic heart failure, and to explore the best pattern of CCM.METHODS: Forty rabbits were divided into 4 groups according to the location of receiving CCM: heart failure (HF) group, left ventricular anterior wall (LVAW-CCM) group, left ventricular posterior lateral wall (LVPLW-CCM) group and right ventricular apex (RVA-CCM) group. The model of chronic heart failure was made by ligating ascending aortic root of the rabbits. After 12 weeks, the electrical stimulations during the absolute refractory period were delivered in different locations of the heart, lasting 6 h everyday for 7 days. The changes of cardiac functions and cardiac dys-synchrony were observed by cardiac ultrasonic cardiogram before and after CCM stimulation. The plasma level of brain natriuretic peptide (BNP) was detected by ABC-ELISA method. Pulsed-wave Doppler was used to acquire aortic pre-ejection interval (APEI) and pulmonary pre-ejection internal (PPEI), and inter-ventricular mechanical delay (IVMD) was calculated to evaluate the cardiac dys-synchrony.RESULTS: Compared with HF group, left ventricular end-systolic dimension (LVESD) and left ventricular end-diastolic dimension (LVEDD) in LVAW-CCM group, LVPLW-CCM group and RVA-CCM group were significantly decreased (P<0.05), while left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) were significantly increased (P<0.05), especially in LVAW-CCM group. Interventricular septal thickness (IVS) and left ventricular posterior wall thickness (LVPW) were similar among groups. No significant difference of plasma BNP level before CCM delivery among the 4 groups was observed. However, the plasma BNP level in control group was the highest, followed by LVPLW-CCM group and RVA-CCM group, and LVAW-CCM group was the lowest after CCM delivery. No change of IVMD was observed among groups before and after CCM delivery.CONCLUSION: The effect of CCM applied to different locations of the heart on cardiac functions is different.The optimal site of CCM delivery is left ventricular anterior wall. No influence of interventricular dys-synchrony was observed during application of CCM.     

Stress induced expression of the angiotensinogen gene in rat anterior pituitary

AIM:To observe the effects of sodium restricted or supplemented on atrial natriuretic polypeptide (ANP) and cardiac function of rats with congestive heart failure (CHF).METHODS:CHF rats were divided into three groups with sham operation rats group as control. Radioimmunassay was used to determine the ANP contents of plasma and myocardium, at the same time cardiac function was measured. RESULTS:In sodium restricted group, the plasma sodium and atrial ANP and left ventricular systolic pressure and artery pressure were obviously lower than those in CHF group, while the plasma and ventricular ANP and the right atrial pressure were remarkably higher; In sodium supplemented group, the plasma sodium and arterial pressure had no obvious change compared with the control, the plasma and myocardium ANP and the right atrial pressure had no difference as compared with CHF group, while the left ventricular end diastolic pressure was remarkably lower and the left ventricular systolic pressure were obviously higher. CONCLUSION:Keeping the balance of plasma sodium by an appropriate supplement of sodium intake after CHF might be beneficial to the ANP biological effects and the cardiac function.