棉纤维细胞伸长生长与过氧化物酶和IAA氧化酶的关系

棉纤维细胞于开花当天从棉胚珠表皮上发生,随即开始伸长生长,星S型生长曲线。棉纤维细胞的可溶性蛋白、过氧化物酶活性和IAA氧化酶活性同伸长生长的关系不大;而离子型结合的细胞壁蛋白质含量、过氧化物酶活性和IAA氧化酶活性同棉纤维细胞的伸长生长关系较大,表现在棉纤维细胞快速伸长期活性较低,而在伸长生长停止时出现活性高峰,同棉纤维细胞的伸长生长有负相关现象。     

Comparative anatomy and morphology of Vitis vinifera (Vitaceae) somatic embryos from solid- and liquid-culture-derived proembryogenic masses

Ontogeny of somatic embryos of grapevine (Vitis vinifera) produced from solid- and liquid-culture-derived proembryogenic masses (PEM) was compared using light and scanning electron microscopy. Somatic embryos produced from solid-medium-derived PEM (SPEM) had large cotyledons, little or no visible suspensor structure, and a relatively undeveloped concave shoot apical meristem, whereas those from liquid-medium-derived PEM (LPEM) had smaller cotyledons, a distinct suspensor, and a flat-to-convex shoot apical meristem. The convex shoot apical meristem in LPEM-derived somatic embryos formed as early as the heart stage of development; it was 4-6 cell layers deep and rich in protein. Suspensors persisted in fully developed and mature LPEM-derived somatic embryos. The SPEM-derived somatic embryos exhibited dormancy, as do mature zygotic embryos, which also have a rudimentary suspensor, whereas LPEM-derived embryos were not dormant. We hypothesize that the presence of a persistent suspensor in LPEM-derived somatic embryos modulates development, ultimately resulting in rapid germination and a high plant-regeneration rate.     

PPF1 inhibits programmed cell death in apical meristems of both G2 pea and transgenic Arabidopsis plants possibly by delaying cytosolic Ca2+ elevation

PPF1 encodes a putative calcium ion carrier that affects the flowering time of transgenic Arabidopsis by modulating Ca(2+) storage capacities in chloroplasts of a plant cell. In the current work, we found that differential expression of PPF1 might affect processes of programmed cell death (PCD) since DNA fragmentation was detected in senescencing apical buds of long day-grown G2 pea (Pisum sativum L.) plants, but was not in non-senescencing short day-grown counterparts at all growth stages. An animal inhibitor of caspase-activated DNase (ICAD) homologue was detected in short day-grown plant continuously throughout the whole experiment and only in early stages of long day-grown pre-floral G2 pea apical buds. DNA fragmentation was significantly inhibited in apical meristems of transgenic Arabidopsis that over-expressed the PPF1 gene when compared to that of either wild-type control or to PPF1 (-) plants. The expression of ICAD-like protein decreased to undetectable level at 45 dpg in apical tissues of PPF1 (-) Arabidopsis, which was much earlier than that found in PPF1 (+) or wild-type controls. In epidermal cells of PPF1 (-) plants, we recorded significantly earlier calcium transient prior to PCD. We suggest that the expression of PPF1, a chloroplast localized Ca(2+) ion channel may inhibit programmed cell death in apical meristems of flowering plants by keeping a low cytoplasmic calcium content that might inhibit DNA fragmentation in plant cells.     

棉花临界需氮量动态定量模型

在大田栽培条件下,于江苏南京和河南安阳两个生态区设置棉花氮素水平试验,基于作物临界氮浓度稀释模型和干物质动态累积模型,建立了棉花花后动态临界氮吸收速率、临界氮需求量的定量化模型.结果表明,两生态区的临界最大氮吸收速率均出现在花后42 d,分别为5.3和4.4 kg·hm^-2·d^-1,临界快速氮累积期分别在花后的23～59 d和23～61 d,安阳的最大临界日需氮量明显大于南京.根据模型得到：安阳生态区适宜施氮量在240～360 kg·hm^-2 之间,且360 kg·hm^-2 条件下其氮累积接近临界需求,南京生态区240 kg·hm^-2施氮量的氮累积与临界值相近.两区域基肥施用量分别占总施肥量的26%和27%,且适宜的追肥时间应在花后22 d左右.由于模型的建立是基于不同氮处理试验,有合理可靠的生理依据,为定量确定不同气候区域的动态施肥量提供了理论依据.     

Endogenous peroxidase in the visceral endoderm of early mouse embryos

Endogenous peroxidase activity was demonstrated in early mouse embryos by means of the diaminobenzidine staining reaction. This enzyme was observed in visceral endoderm on the seventh to eighth day of gestation in vivo, but was no longer detected on the ninth day of development. In cell layers developing from blastocysts or isolated inner cell masses cultured for 96-144 h (developmental stage equivalent to 6-7.5-day-old embryos), diaminobenzidine product was also observed in visceral endodermal cells. Most of the endogenous peroxidase was localized inside or close to the numerous apical vacuoles in the endoderm. Ectoderm, mesoderm, ectoplacental cone, and trophoblast cells did not contain endogenous peroxidase.     

Fluctuation in levels of endogenous plant hormones in ovules of normal and mutant cotton during flowering and their relation to fiber development

The contents of indole-3-acetic acid (IAA), gibberellins (GAs), abscisic acid (ABA), and cytokinins were determined in ovules of normal cotton (Tm-1) and a kind of fiber differentiation mutant (Xin) before and after flowering by enzyme-linked immunosorbent assays. It was found that 24 h before flowering, a peak of IAA content was observed in ovules of Tm-1, whereas in ovules of Xin, a low level of IAA was determined. From –1 day (1 day before flowering) to +3 days (3 days after flowering), GA₁₊₃ levels in ovules of Xin were 40–70% lower than those of Tm-1; GA₄₊₇ levels were very low, and there was no visible difference in GA₄₊₇ content between normal and mutant cotton. The ABA content in ovule of Tm-1 decreased by 70% 3 days after flowering, whereas that of Xin only decreased by 20%. The levels of cytokinins in ovules of Tm-1 decreased after flowering, and those of Xin kept up a steady increase.Abbreviations IAA indole-3-acetic acid - GA gibberellin - ABA abscisic acid - ELISA enzyme-linked immunosorbent assay - FW fresh weight - PBS phosphate-buffered saline - iPA isopentenyladenosine - ZR zeatin riboside - DHZR dihydrozeatin riboside - CTK cytokinin     

Polyamine translocation following photoperiodic flowering induction in soybean

Radioactivity translocation after [¹⁴C]-spermidine application over the third trifoliate leaf of soybean plants ( Glycine max . [L.] Merr, cv. Williams) was checked during the first 72 h of short day (SD) treatment to study the involvement of polyamines (PAs) in photoperiodic flowering induction. PAs and/or their metabolites were translocated from the supplied leaf to all parts of the plant. Radioactivity reached its highest concentration in the upper portion of the stem, i.e. the apical bud and the youngest leaf. After the beginning of the first inductive night, the detected radioactivity showed two peaks of maximal concentration. The first arose after the first inductive night, coinciding with the proper flowering induction process; the second one arose after the third inductive night, coinciding with the first morphological symptoms of the transition of vegetative meristems to the reproductive condition. Soluble free PAs showed a different balance in the apical bud of SD-induced plants compared with LD-non induced control plants. Soluble conjugated PAs were detected as traces. It is suggested that under flowering inductive conditions, PAs play a different role according to the stage of the flowering process. Thus, their translocation from the leaves to the axillary and apical buds might be related, in a first step, to the fact that they were part of the complex mechanism of the flowering signal, and in a second step, to the flower transition of vegetative buds.     

Levels of Cytokinins in the Ovules of Cotton Mutants with Altered Fiber Development

Endogenous levels of cytokinin and abscisic acid (ABA) were determined in ovules of normal cotton (TM-1) and four fiber differentiation mutants (n2, Ligon lintless, H10, and Xu142) before and after flowering by enzyme-linked immunosorbent assays. The fluctuation patterns of ABA levels in ovules of normal cotton and mutants were similar. At the fiber elongation stage, ABA content was low, and from 1 day after flowering, the ABA content decreased steadily. On the other hand, the peaks of isopentenyladenine and isopentenyladenosine in ovules of TM-1 were observed 1 day before flowering. The level of cytokinins decreased after flowering in TM-1, whereas in the mutants it increased steadily. These results indicate that endogenous ABA is probably not the main inhibitor for fiber elongation and that endogenous cytokinins likely play a dual role in fiber development. Before flowering, cytokinins function as one of the stimuli for the initiation of fibers, but after flowering, cytokinins inhibit fiber growth. Received February 18, 1997; accepted June 11, 1997     

Polarized expression of an apical membrane glycoprotein is established before functional tight junctions have developed in MCF-7 cells

A milk-fat globule membrane antigen, designated MAM-6 and detected immunocytochemically by the monoclonal antibody 115D8, is expressed apically in confluent MCF-7 monolayer cultures. Immediately after preparation of a single-cell suspension, MAM-6 appears on the entire cell surface. However, polarized apical expression of MAM-6 is restored as early as 2-6 hr after plating of unpolarized cells, before functional tight junctions are established, as judged by freeze-fracture and ruthenium red permeability. Quantitative immunogold cytochemistry reveals that the apical:basal ratio of MAM-6 expression was about 17:1 after 6 hr. Tight junctions developed as late as 12-24 hr after plating. At this time the apical:basal MAM-6 ratio was about 30:1 (as compared to about 50:1 in control monolayers).     

Inhibition of growth and synchronised cell division in the shoot apex in relation to flowering in Silene

When plants of Silene coeli-rosa (L.) Godron were induced by seven long days, then exposed to darkness for 48 h before being returned to short days, they went on to initiate flowers with a delay of about 2 d. The synchronisation of cell division which normally occurs before flower initiation was suppressed, showing that it is not essential for flowering. Periods of darkness of up to 240 h inhibited apical growth and leaf initiation but did not prevent eventual flowering in short days. The commitment of the apex to flower was therefore maintained while apical growth was inhibited.Abbreviations SD short day(s) - LD long day(s)     

棉田捕食性天敌群落动态研究

对安徽沿江棉田捕食性天敌群落动态进行了研究。结果表明,棉田捕食性天敌种类很多,共记录19种,主要优势种为龟纹瓢虫,草间小黑蛛,八斑球腹蛛,三突花蛛,小花蝽和三色长蝽,捕食性天敌数量丰富,但雨季较少,优势种中龟纹瓢虫,三突花蛛,小花蝽和三色长蝽主要分布于棉株上部和中部,草间小黑蛛和八斑球腹蛛主要分布于棉株中,下部,群落多样性在棉花生育期前期较高,7月上旬棉花蕾花期达最大值,此后不断下降,影响群落多样性的主要因子,在棉花生育前期（苗期至蕾花期）是物种丰富度,在棉花生育后期（花铃期至吐絮期）是均匀度。群落特征在8月中旬前棉花苗期至花铃期较为类似,以后群落优势种特征日益突出,群落变化显著。     

Effects of water stress and rewatering on photosynthesis,root activity,and yield of cotton with drip irrigation under mulch

Soil water deficit is a major limitation to agricultural productivity in arid regions. Leaf photosynthesis can quickly recover after rewatering and remains at a higher level for a longer period, thus increasing crop yield and water-use efficiency (WUE). We tested our hypothesis that leaf photosynthesis and root activity of water-stressed cotton (Gossypium hirsutum L.) plants could quickly recover after rewatering at a certain growth stage and it should not influence a cotton yield but increase WUE. Treatments in this study included two degrees of water stress: mild water stress (V₁) and moderate water stress (V₂) imposed at one of four cotton growth stages [i.e., S₁ (from the full budding to early flowering stage), S₂ (from early flowering to full flowering), S₃ (from full flowering to full bolling), and S₄ (from full bolling to boll-opening)]. The soil water content before and after the water stress was the same as that in the control treatment (CK, 70–75% of field capacity). Water deficit significantly reduced the leaf water potential, net photosynthetic rate, and stomatal conductance in cotton. The extent of the decline was greater in S₂V₂ treatment compared to others. Water deficit also reduced root activity, but the extent of inhibition varied in dependence on soil depth and duration. When plants were subjected to S₁V₁, the root activity in the 20–100 cm depth recovered rapidly and even exceeded CK one day after rewatering. An overcompensation response was observed for both photosynthesis and aboveground dry mass within one to three days after rewatering. Compared with the CK, S₁V₁ showed no significant effect on the yield but it increased total WUE and irrigation WUE. These results suggest that even a short-term water stress during the S1, S2 and S4 stages mitigated, with respect to the root activity, the negative effect of drought and enhanced leaf photosynthesis compensatory effects of rewatering in order to increase cotton WUE with drip irrigation under mulch in arid areas.     

Protein-Energy Malnutrition Developing after Global Brain Ischemia Induces an Atypical Acute-Phase Response and Hinders Expression of GAP-43

Protein-energy malnutrition (PEM) is a common post-stroke problem. PEM can independently induce a systemic acute-phase response, and pre-existing malnutrition can exacerbate neuroinflammation induced by brain ischemia. In contrast, the effects of PEM developing in the post-ischemic period have not been studied. Since excessive inflammation can impede brain remodeling, we investigated the effects of post-ischemic malnutrition on neuroinflammation, the acute-phase reaction, and neuroplasticity-related proteins. Male, Sprague-Dawley rats were exposed to global forebrain ischemia using the 2-vessel occlusion model or sham surgery. The sham rats were assigned to control diet (18% protein) on day 3 after surgery, whereas the rats exposed to global ischemia were assigned to either control diet or a low protein (PEM, 2% protein) diet. Post-ischemic PEM decreased growth associated protein-43, synaptophysin and synaptosomal-associated protein-25 immunofluorescence within the hippocampal CA3 mossy fiber terminals on day 21, whereas the glial response in the hippocampal CA1 and CA3 subregions was unaltered by PEM. No systemic acute-phase reaction attributable to global ischemia was detected in control diet-fed rats, as reflected by serum concentrations of alpha-2-macroglobulin, alpha-1-acid glycoprotein, haptoglobin, and albumin. Acute exposure to the PEM regimen after global brain ischemia caused an atypical acute-phase response. PEM decreased the serum concentrations of albumin and haptoglobin on day 5, with the decreases sustained to day 21. Serum alpha-2-macroglobulin concentrations were significantly higher in malnourished rats on day 21. This provides the first direct evidence that PEM developing after brain ischemia exerts wide-ranging effects on mechanisms important to stroke recovery.     

Physiological causes of cotton fruit abscission under conditions of high temperature and enhanced ultraviolet-B radiation

An experiment was conducted in sunlit controlled environment growth chambers to determine the physiological mechanisms of fruit abscission of cotton ( Gossypium hirsutum L. cv. NuCOTN 33B) grown in high temperature and enhanced ultraviolet (UV)-B radiation. Six treatments included two levels of optimum (30/22°C) and high (36/28°C) day/night temperatures and three levels of biologically effective UV-B radiation (0, 7, and 14 kJ m⁻² per day). Both the temperature and UV-B treatments were imposed from seedling emergence through 79 days after emergence (DAE). High temperature did not negatively affect either leaf net photosynthetic rates (Pn) or abscission of cotton squares (floral buds with bracts) but significantly decreased boll retention. Plants exposed to 7 kJ UV-B radiation retained 56% less bolls than the 0 kJ UV-B control plants at 79 DAE, despite no significant differences in leaf Pn measured at squaring and flowering. At 53 DAE, leaf Pn of plants grown in high UV-B radiation (14 kJ m⁻² per day) decreased by 11%, whereas total non-structural carbohydrate (TNC) concentrations in the leaves, floral buds, and young bolls decreased by 34, 32, and 20%, respectively, compared with the control plants. The high UV-B radiation significantly increased square abscission. Square abscission was not related to leaf TNC concentration but closely correlated with TNC in floral buds ( r  = −0.68, P  < 0.001). Young boll abscission was highly correlated with TNC concentrations in both the leaves ( r  = −0.40, P  < 0.01) and the bolls ( r  = −0.80, P  < 0.001). Our results indicate that non-structural carbohydrate limitation in reproductive parts was a major factor associated with fruit abscission of cotton grown under high temperature and enhanced UV-B radiation conditions.     

Effects of uniconazole and GA3 on cold-induced stem elongation and flowering of Raphanus sativus L.

The effects of gibberellin (GA) on cold-induced stem elongation and flowering of Japanese radish (Raphanus sativus L.) were investigated using application of GA3 and a GA-biosynthesis inhibitor, uniconazole (UCZ). UCZ very strongly inhibited stem elongation and delayed flowering, and the inhibition and delay were completely reversed by GA3 application. These results suggest that GA is necessary not only in the stem elongation but also in the flowering. When cold treatment (CT) was conducted on the plants whose GA level was lowered by UCZ, GA3 applied after CT completely reversed the delay of flowering. Thus low GA level probably did not retard cold induction. Microscopic observation of apical meristem showed that UCZ delayed flowering by delaying the shift from vegetative to dome-shaped meristem. This result suggested that low GA level delayed floral evocation. Consequently it was suggested that low GA level retarded physiological process involved in long day induction or in floral evocation, resulting in delay of floral evocation.     

Expression of matrix metalloproteinase -2, -9 and tissue inhibitors of metalloproteinase -1, -2, -3 mRNAs in rat uterus during early pregnancy

Zymography and in situ hybridizition were used to investigate matrix metalloproteinase-2, -9 (MMP-2, -9) activities, and expression of mRNAs for MMP-2, -9 and tissue inhibitors of matrix metalloproteinases (TIMP-1, -2, -3) in the rat uterus during early pregnancy (day 1-7). The zymography results showed two forms of MMP-2 (64 and 67 kDa) in the rat uteri during early pregnancy. The 64-kDa MMP-2 activity was the highest on day 2 (P < 0.01) and higher on day 5 and 6 (P < 0.05). The 67-kDa MMP-2 activity reached the highest on day 5 and 6 (P < 0.01). The 64-kDa MMP-2 activity at the implantation sites was higher than those at interimplantation sites (P < 0.05). Furthermore, the 67 kDa MMP-2 can be converted to 64 kDa forms by incubation with p-aminophenylmercuric acetate (APMA) and trypsin in vitro. The 92-kDa MMP-9 activity was only detected on day 5 and 6 of pregnancy (P < 0.01). In situ hybridization showed that on day 1-4 of pregnancy, both MMP-2 and TIMP-2 mRNAs were evidently localized in the basal stromal cells. On day 5, MMP-2 mRNA signals were decreased in the basal stromal cells and mRNA for TIMP-2 was expressed in the epithelial cells and subepithelial stromal cells. The mRNAs for MMP-9, TIMP-1, and -3 were mainly expressed in epithelial cells on day 1-5. At the implantation site on day 6, the mRNAs for MMP-2, -9, TIMP-1, -2, and -3 were highly expressed in the primary decidual zone surrounding the implanting embryo, and in the whole decidualized stromal cells (the primary and secondary decidual zones) at the implantation site on day 7. The intensities of mRNAs for the TIMPs in decidualized stromal cells at the implantation site on day 6 and 7 were stronger than those for the MMPs. The weak mRNAs for MMP-2, -9, TIMP-1, and -3 but not TIMP-2 were also observed in the ectoplacental cone/trophoblastic cells of the implanting embryos. However, at the interimplantation sites on day 6 and 7, MMP-2, -9, TIMP-1, -2, and -3 mRNAs were weakly expressed in the epithelial cells, subepithelial stromal cells, and myometrium. The results suggested that the implanting rat embryo strongly induced MMP-2 and -9 proteins and gene expression for decidulization and embryo invasion, which were strictly controlled and balanced by the simultaneous expression of TIMP-1, -2 and -3.     

小桐子花的性别与开花时间的相互关系

通过对小桐子(Jatropha curcas L.)花序上小花的开花顺序和小花性别的观察,发现其聚伞花序中心花的性别与其开花时间相关联,同时还和周围其它小花的性别有很大的相关性.中心花若在整个花序开花的第一天开放,仅有23.2%的可能是雌花;若在第二天及以后开放,有85%以上的可能为雌花.而中心花的性别又与其它花的性别相关,中心花如为雌花,那么聚伞花序上的其它小花有80%的可能性为雌花;但中心花若为雄花,那么整个聚伞花序上将不会再有雌花.研究小桐子的开花行为及性别控制规律,对于进一步人工调控小桐子花的性别表达,提高小桐子的产量、培育高产稳产品种,具有重要的应用价值.