低温对杜果花粉母细胞减数分裂过程中核仁及染色体行为的影响

采用改良涂片法对低温和常温条件下卡亡果‘台农1号’和‘Irwin’花粉母细胞减数分裂过程进行观察,结果表明：卡亡果花粉母细胞胞质分裂为同时型。常温（25-30℃）条件下,花粉母细胞减数分裂过程较为正常,双线期染色体主要形成二价体,二价体构型以“V”、“O”、“Y”、“X”型、点状和棒状等形式存在,以点状、“V”和“O”型较多见,出现少量的单价体和多价体,其中台农1号为0．79％和4．76％,Irwin为0和3．57％;同时仅在少量中期Ⅱ和后期Ⅱ花粉母细胞中观察到落后染色体。低温（10—20℃）条件下,减数分裂过程中核仁的行为发生大量异常,微核仁的平均检出率高达22．88％,明显高于常温条件下的平均值（4．56％）;双线期单价体和多价体的发生频率有明显增加,其中台农1号中为8．82％和17．65％,Irwin中为14．52％和24．19％;减数分裂中期Ⅰ、Ⅱ及后期Ⅰ、Ⅱ均观察到落后染色体,其中台农1号的异常率为12．73％、5．63％、15．79％和4．76％,Irwin为11．11％、7．61％、9．52和6．38％。低温条件下减数分裂异常可能是造成雄性不育的重要原因。     

苹果品种资源2n花粉普查

本试验对苹果属６３个品种或类型小孢子母细胞减数分裂四分体时期进行观察，发现有３８个品种或类型四分体时期存在异常分裂相，出现二分体或三分体；同一品种或类型的不同花朵以及同一花朵的不同花药间二分体百分率差异不显著，对９９个品种或类型的花粉粒观察发现，８９个二倍体品种或类型中，有３３个存在２ｎ花粉粒，占品种总数的３７％，其中１６个２ｎ花粉百分率大于０．０４％，２Ｘ品种四分体时期二分体百分率与花粉粒中２ｎ花粉百分率无显著相关     

同源四倍体青花菜花粉母细胞的减数分裂

 以同源四倍体青花菜为材料, 采用常规压片法研究花粉母细胞减数分裂行为。结果表明: 同源四倍体青花菜花粉母细胞减数分裂过程与二倍体基本相同但有其特殊性。主要表现在: 中期Ⅰ染色体的构型复杂, 有多价体、四价体、三价体、二价体和单价体; 中期Ⅰ和中期Ⅱ有赤道板外染色体; 后期Ⅰ和后期Ⅱ出现落后染色体、染色体桥及断片; 后期Ⅱ和末期Ⅱ还出现染色体分离不同步及不等分裂的现象;四分体时期出现二分体、三分体、含微核的异常四分体及多分体。花粉母细胞减数分裂平均异常频率为31.5% , 是同源四倍体青花菜花粉育性低的细胞学原因。     

不同倍性蝴蝶兰未减数雄配子的发生及其细胞学机理初探

采用压片法对不同倍性蝴蝶兰品种小孢子母细胞减数分裂及成熟花粉进行观测,并利用流式细胞仪测定了花粉中的DNA含量,发现除了单倍性配子外,均有少数未减数配子发生。不同倍性蝴蝶兰品种中单倍性、二倍性、三倍性和四倍性花粉平均直径分别为11.4、17.2、19.1和20.3 μm,花粉直径与倍性呈正相关关系（r = 0.935,P < 0.065）;二倍体、三倍体和四倍体蝴蝶兰品种未减数雄配子的平均发生率分别为0.59%、2.39%和0.67%,三倍体品种发生未减数雄配子的频率明显高于二倍体和四倍体品种;二倍体、三倍体和四倍体品种均通过二分体和三分体的方式形成未减数雄配子,其中二分体的形成是由于小孢子母细胞不进行减数分裂Ⅰ,而正常进行减数分裂Ⅱ所致,三分体的形成可能是由于纺锤体异常定位形成三极纺锤体所致。     

马铃薯花粉原生质体分离的研究

以马铃薯减数分裂二分体和四分体时期的小孢子为材料，对原生质体分离的主要影响因素进行了研究。结果表明，１％蜗牛酶和０．５％崩溃酶的混合酶液游离效果最好，原生质体的最高得率达６５．４％。渗透压调解剂以蔗糖最好，甘露醇次之，最适浓度分别为１６％和１８％。０．１％荧光增白剂检测表明脱壁完全，ＦＤＡ荧光检测表明花粉原生质体具有生活力。     

秋水仙素处理后‘无核丰’枣的减数分裂行为及2n花粉的形成

运用压片法对秋水仙素滴注处理后的‘无核丰’枣小孢子母细胞减数分裂行为及其与花蕾外部形态变化的相关性进行了研究,并测定了2n花粉的比例。结果表明:秋水仙素处理后枣小孢子母细胞第一次减数分裂正常;在减数分裂前期Ⅱ观察到胞质分裂异常现象;中期Ⅱ纺锤体主要有4种类型:平行型、垂直型、八字型和融合型,分别占27.31%、19.35%、45.27%和8.06%;四分体时期观察到二分体、三分体、四分体,分别占6.00%、43.04%、50.96%;定位异常纺锤体八字型与融合型分别与三分体、二分体呈正相关;秋水仙素处理后‘无核丰’枣2n花粉的形成受胞质分裂异常、纺锤体定位异常两种机制控制,因纺锤体定位异常而产生的2n花粉占2n花粉总数的96.97%,遗传上等同于FDR(第1次分裂重组)型配子,因胞质分裂异常产生的2n花粉在遗传上等同于SDR(第2次分裂重组)型配子;秋水仙素处理后‘无核丰’枣2n花粉绝大多数为FDR型,因而在枣有性多倍化中具有重要的利用价值。小孢子母细胞减数分裂进程与花蕾外部形态变化具有对应关系,花蕾直径达到1.34 mm时,小孢子母细胞开始进入减数分裂;达到1.68 mm时,小孢子母细胞进入四分体时期;超过1.92 mm时,减数分裂结束,且有大量花粉粒形成。2n花粉诱导最佳的秋水仙素滴注时期为细线期末期,即花蕾直径在1.34~1.42 mm时,诱导后‘无核丰’枣2n花粉发生比例为17.36%。     

马铃薯2n配子发生的遗传分析

马铃薯２ｎ配子的研究为二倍体野生种的利用开辟了一条新途径。本文首次对两个群体共８个不同亲本的２ｎ花粉发生频率的选择标准、相关性、配合力、遗传力及有关问题进行了探讨。结果表明，２ｎ花粉发生的广义遗传力为５１．６６％～４５．３５％，狭义遗传力为２０．０８％～１４．８９％。这说明遗传加性效应很低。特殊配合力对２ｎ花粉发生起主导作用。２ｎ花粉频率很大程度上取决于组合中大于５％２ｎ花粉基因型的频率而不是组合的最高频率。２ｎ花粉的轮回选择应从组合平均数高的群体中开始进行。     

四倍体甜瓜花粉母细胞减数分裂的观察

以同源四倍体甜瓜为材料,采用常规压片法研究花粉母细胞减数分裂行为。结果表明:同源四倍体甜瓜花粉母细胞减数分裂过程与二倍体类似,但有其特殊性。主要表现在:粗线期观察到有6.7%的细胞出现双核;终变期的四倍体染色体构型较复杂,有二价体、多价体、三价体和单价体;中期I和中期II有赤道板外染色体;后期I和后期II出现染色体桥和落后染色体;四分体时期出现二分体、三分体和多分体。花粉母细胞减数分裂的异常是同源四倍体甜瓜育性低的细胞学原因。     

高温对桃花粉发育及小孢子产生的影响

在人工气候培养箱内对‘锦绣’黄桃（Prunus persica‘Jinxiu’）花器官进行高温处理,利用光学显微镜探讨了高温对小孢子形成和花粉发育的影响。结果表明：与对照相比,35 ℃高温处理1 h 对花粉量影响不显著,随着处理时间增加,花粉量、萌发率以及花粉管生长量显著下降,5 h 高温处理的花粉量仅为对照的1.9%,且基本不萌发;5 h 高温处理部分花粉母细胞减数分裂后不能形成正常的四分体,而形成二分体、三分体以及多分体。随着花药胼胝质的解体,花药内出现了多核小孢子。高温处理后小孢子细胞质收缩解体,随后小孢子壁也解体;高温处理的花药壁细胞染色浅,绒毡层提前解体,说明绒毡层不能继续为小孢子发育提供营养物质,使小孢子发育受阻,造成小孢子逐渐消失。     

温度对桃性器官发育的影响

在可控温度生长箱内，研究了４个昼／夜温度处理对二年生盆载早露蟠桃性器官发育的影响。结果表明，随着温度的升高，性器官发育速度加快，败育趋势增加。（１）与２０－１５℃处理相比，２５／１５℃、３０／１５℃处理花粉粒成熟期分别提前３、６ｄ；花粉粒数量分别减少５４％、８６％；３５／１５℃处理花粉母细胞减数分裂异常，造成雄笥完全败育；９２）与２０／１５℃７１处理相比，２５＝／１５     

Relationship between renal hypertension and cardiac α1-adrenoceptor autoantibodies in rats

AIM: To examine the autoantibody against α₁-adrenoceptor and its biologic activities during the development of renal hypertension. METHODS: Renal hypertension of rat was achieved by clipped renal artery, the titre of autoantibody to α₁-adrenoceptor was detected using ELISA immunoassay. Furthermore, the biological offects of these autoantibodies on cultured cardiomyocytes were also examined. RESULTS: After two weeks of clipping renal arteries, both the frequency of occurrence and the titre of autoantibodies to cardiac α₁-adrenergic receptor were significantly increased as compared with the control of pre-treatment. The increased autoantibodies lasted for several weeks and then automatically decreased gradually to the pre-clipping level at 12 weeks. The biological effects of these autoantibodies displayed an "agonistic-like" activities on the beating frequency of cultured neonatal cardiomyocytes. CONCLUSION: Autoantibodies against α₁-adrenoceptor may play a role in the elevation of peripheral vascular resistance and in the development of cardiac hypertrophy in rats with renal hypertension.     

Effects of radiation from 188Re on smooth muscle cell proliferation

AIM: Although endovascular radiotherapy inhibits neointimal hyperplasia, the exact alterations induced by β-particles irradiation remain to be elucidated. The objective of this study was to investigate the ability and the cellular mechanism of local β^-particles emission from ¹⁸⁸Re to inhibit vascular smooth muscle cells (SMCs). METHODS: The SMCs in vitro were irradiated by ¹⁸⁸Re with single doses of 2.6 Gy-25.8 Gy. The effects of β-particles on SMCs, such as effective irradiate doses, the period of inhibition for SMCs proliferation, the changes of cell proliferation rate and DNA synthesis rate, cell cycle progression and related gene expression, were investigated by cell count, [³H]-TdR incorporation, cell cycle progression analysis, cell viability and immunocytochemistry, respectivecy. RESULTS: β-particles irradiation with dose of 5.2 Gy could inhibit significantly SMCs proliferation. At dose of 20.6 Gy DNA synthesis inhibitory rate was 92%, SMCs proliferation rate was only 3%. Renoval of ¹⁸⁸Re did not abolish the inhibitory effects of β-particles on SMCs proliferation. The expression of P53 was up regulation and PCNA was down regulation after irradiation. CONCLUSION: β-particles from ¹⁸⁸ Re was significantly effective and permanent in inhibiting SMCs proliferation, and inhibitory effect was in dose-dependet manner ED50was 5 Gy, the best dose to inhibit SMCs proliferation was 20 Gy. β-particles irradiation induced SMCs to occur G₀/G₁ arrest, damaged the ability of SMCs reproliferation and led to cell clonogenic death. P53 and PCNA had regulatiory effects on SMCs proliferation after β-particles irradiation.     

Influence of Mineral Nutrients on Strawberry Fruit Quality and Their Accumulation in Plant Organs

Abstract

This review is based partly on complete articles and partly on abstracts. Three of the 60 articles deal with the total uptake of elements in strawberry plant organs in two different strawberry production systems, both considered as optimal concerning amount and balance of elements. The effect on fruit quality may be dramatic if the level of a particular element is outside this range, but there may also be effects initiated by differences within the optimal range of elements. Most articles refer to product oriented quality, but some focus on consumer oriented quality, as discussed by Shewfelt (1999). The discussion here is on a general basis, so one should keep in mind that there are cultivar differences and that specification of nutrition ideally should mirror the needs of a single cultivar, or a group of cultivars with similar requirements. Also, to get a complete understanding of the subject future reviews should embrace a broader access of information including the effect on plant development of individual elements, such as the role of calcium in fruit firmness and its importance in cell wall structure. However, the intention here is to narrow the information to results that suggest a direct connection between nutrient uptake and fruit quality.     

Mixed-severity fire regime in a high-elevation forest of Grand Canyon,Arizona, USA

Fire regime characteristics of high-elevation forests on the North Rim of the Grand Canyon, Arizona, were reconstructed from fire scar analysis, remote sensing, tree age, and forest structure measurements, a first attempt at detailed reconstruction of the transition from surface to stand-replacing fire patterns in the Southwest. Tree densities and fire-/non-fire-initiated groups were highly mixed over the landscape, so distinct fire-created stands could not be delineated from satellite imagery or the oldest available aerial photos. Surface fires were common from 1700 to 1879 in the 4,400 ha site, especially on S and W aspects. Fire dates frequently coincided with fire dates measured at study sites at lower elevation, suggesting that pre-1880 fire sizes may have been very large. Large fires, those scarring 25% or more of the sample trees, were relatively infrequent, averaging 31 years between burns. Four of the five major regional fire years occurred in the 1700s, followed by a 94-year gap until 1879. Fires typically occurred in significantly dry years (Palmer Drought Stress Index), with severe drought in major regional fire years. Currently the forest is predominantly spruce-fir, mixed conifer, and aspen. In contrast, dendroecological reconstruction of past forest structure showed that the forest in 1880 was very open, corresponding closely with historical (1910) accounts of severe fires leaving partially denuded landscapes. Age structure and species composition were used to classify sampling points into fire-initiated and non-fire-initiated groups. Tree groups on nearly 60% of the plots were fire-initiated; the oldest such groups appeared to have originated after severe fires in 1782 or 1785. In 1880, all fire-initiated groups were less than 100 years old and nearly 25% of the groups were less than 20 years old. Non-fire-initiated groups were significantly older (oldest 262 years in 1880), dominated by ponderosa pine, Douglas-fir, or white fir, and occurred preferentially on S and W slopes. The mixed-severity fire regime, transitioning from lower-elevation surface fires to mixed surface and stand-replacing fire at higher elevations, appeared not to have been stable over the temporal and spatial scales of this study. Information about historical fire regime and forest structure is valuable for managers but the information is probably less specific and stable for high-elevation forests than for low-elevation ponderosa pine forests.This revised version was published online in May 2005 with corrections to the Cover Date.     

瓜叶绿素降解关键酶基因PPH和PAO cDNA片段的克隆与表达初步分析

 以西双版纳黄瓜和‘华黄5号’黄瓜叶片为试验材料,研究了衰老过程中两种黄瓜叶片叶绿素含量变化及脱镁叶绿素脱镁叶绿酸水解酶基因PPH和脱镁叶绿酸a加氧酶基因PAO的表达。结果表明：随着叶片衰老,叶绿素a和叶绿素b含量显著降低,叶绿素a与叶绿素b的比值在0.5左右,推测叶绿素b的含量可能对黄瓜叶片保绿起到重要作用。荧光定量RT-PCR分析结果显示：PPH和PAO在西双版纳黄瓜叶片生长35 d时表达量最高,分别为5.50和1.86;PPH在‘华黄5号’叶片35 d时表达量最高,为7.14,而PAO在35和45 d表达量都很高,分别为3.90和3.91;PPH和PAO在西双版纳黄瓜叶片中的表达量低于在‘华黄5号’中。     

Effects of simvastatin on PDGF-BB and serum-induced proliferation of vascular smooth muscle cells and on the expression of tumor suppressor gene PTEN

AIM:To observe the effect of simvastatin on the proliferation of vascular smooth muscle cells(VSMCs) induced by serum and growth factor PDGF-BB and the effect of simvastatin on the expression of PTEN,a important regulator of G₁/S cell cycle transition. METHODS:The DNA synthesis was determined by [³H]-TdR incorporation, cell cycle was examined with flow cytometry, the protein level of PTEN was measured by Western blot method. RESULTS: (1)Simvastatin inhibited [³H]-TdR incorporation in a dose dependent manner. (2) Flow cytometric DNA analysis revealed that simvastatin induced significantly enhancement of G₀/G₁ phase and decrease in S phase VSMCs.(3)Simvastatin increased protein level of PTEN and mevalonate, a metabolite of HMG-COA, reversed the effect of simvastatin on PTEN protein expression. CONCLUSION:Simvastatin may inhibit proliferation of VSMCs and retarded cell cycle in G₀/G₁ phase by increasing PTEN expression through inhibiting synthesis of mevalonate.     

Relationships of landscape,prey and agronomic variables to the abundance of generalist predators in cotton (<Emphasis Type="Italic">Gossypium hirsutum</Emphasis>) fields

A two-year field study investigated the possible effects of grain sorghum (Sorghum bicolor [L.] Moench) and uncultivated areas on the abundance of generalist predators in commercially-managed cotton (Gossypium hirsutum L.) fields in Texas, USA. From 63 to 70 fields were sampled for pests and predators over nine consecutive weeks during early stages of cotton development. Additional data on agronomic practices and landscape composition at three spatial scales were also collected for each field. Stepwise regression analyses were used to determine the relationships of landscape, agronomic and prey variables to the abundance of generalist predators. Because the variables most closely linked to predator levels could vary over time, separate regressions were conducted for three time periods corresponding to stages of grain sorghum growth (half-bloom, hard-dough, maturity) in each year. Significant relationships between predator abundance and agricultural landscape composition appear in both years and in all three time periods, but the specific relationships of landscape variables to cotton predator levels differed between and within years. At maturity in 2001, predator levels rose as the amount of uncultivated land from 1.6 to 3.2 km distant and the perimeter shared with grain sorghum increased. During 2002, the area of grain sorghum (half-bloom) and uncultivated land (hard-dough) within 1.6 km of cotton fields were both positively related to predator numbers. Cotton planting dates and the abundance of cotton fleahoppers (Pseudatomoscelis seriatus [Reuter]) were also strongly linked to predator numbers during both years. Results suggest that the total amount of grain sorghum or uncultivated land in an area is more important than the presence of these habitats adjacent to cotton fields, and that landscape composition may sometimes be the most important factor in determining predator abundance.     

多效唑对猕猴桃离体试管苗生长及内源激素的影响

多效唑（ＰＰ３３３）处理猕猴桃试管苗，降低了其生长强度；植株体内的ＧＡ３、ＩＡＡ和ＺＴ含量下降，ＡＢＡ的含量上升，乙烯释放率增加；并且能降低外源的ＧＡ３和ＩＡＡ促进生长的作用，而外源的ＧＡ３和ＩＡＡ又能不同程度地逆转多效唑的抑制作用，使植株恢复生长。     

Proteomic analysis between pathological scars and normal skin

AIM: To investigate and screen the sensitive proteins in the formation mechanism of pathological scars by comparing the results of differential proteomic analysis between pathological scars and normal skin.METHODS: Two-dimensional gel electrophoresis was used to detect the protein expression profiles in 8 keloid patients, 8 hypertrophic scar patients and 3 matched normal skin patients.The proteins that showed differential expression of over 4-fold change were cut and analyzed by MALDI-TOF/TOF mass spectrometry.RESULTS: A two-dimensional protein profiling comparison between pathological scars and normal skin was successfully established.On average, 2 978 spots in keloid, 2 975 spots in hypertrophic scar and 3 053 spots in normal skin were identified using gel analysis software.Compared with normal skin, there were totally 36 differentially-expressed proteins in keloid and hypertrophic scar identified from the spots of over 4-fold change, including 16 proteins in both keloid and hypertrophic scar (8 up-regulated and 8 down-regulated), 11 only in keloid (9 up-regulated and 2 down-regulated) and 9 only in hypertrophic scar (4 up-regulated and 5 down-regulated).CONCLUSION: Proteomic analysis can identify the proteins with variance of pathological scars versus normal skin, thus providing probable new clues to reveal the formation mechanism of pathological scars.     

Coupling past management practice and historic landscape change on John F. Kennedy Space Center,Florida

Historic landcover dynamics in a scrubby flatwoods (Tel-4) and scrub landscape (Happy Creek) on John F. Kennedy Space Center were measured using aerial images from 1943, 1951, 1958, 1969, 1979, and 1989. Landcover categories were mapped, digitized, geometrically registered, and overlaid in ARC/INFO. Both study sites have been influenced by various land use histories, including periods of range management, fire suppression, and fire management. Several analyses were performed to help understand the effects of past land management on the amount and spatial distribution of landcover within the study sites. A chi-squared analysis showed a significant difference between the frequency of landcover occurrence and management period. Markov chain models were used to project observed changes over a 100-year period; these showed current management practices being effective at Tel-4 (restoring historic landscape structure) and much less effective at Happy Creek. Documenting impacts of past management regimes on landcover has provided important insight into current landscape composition and will provide the basis for improving land management on Kennedy Space Center and elsewhere.