Time-lapse imaging of self- and cross-pollinations in Brassica rapa

Background and Aims

Pollination is an important process in the life cycle of plants and is the first step in bringing together the male and female gametophytes for plant reproduction. While pollination has been studied for many years, accurate knowledge of the morphological aspects of this process is still far from complete. This study therefore focuses on a morphological characterization of pollination, using time-series image analysis of self- and cross-pollinations in Brassica rapa.

Methods

Time-lapse imaging of pollen behaviour during self- and cross-pollinations was recorded for 90 min, at 1 min intervals, using a stereoscopic microscope. Using time-series digital images of pollination, characteristic features of pollen behaviours during self- and cross-pollinations were studied.

Key Results

Pollen exhibited various behaviours in both self- and cross-pollinations, and these were classified into six representative patterns: germination, expansion, contraction, sudden contraction, pulsation and no change. It is noteworthy that in ‘contraction’ pollen grains shrunk within a short period of 30–50 min, and in ‘pulsation’ repeated expansion and contraction occurred with an interval of 10 min, suggesting that a dehydration system is operating in pollination. All of the six patterns were observed on an individual stigma with both self- and cross-pollinations, and the difference between self- and cross-pollinations was in the ratios of the different behaviours. With regard to water transport to and from pollen grains, this occurred in multiple steps, before, during and after hydration. Thus, pollination is regulated by a combination of multiple components of hydration, rehydration and dehydration systems.

Conclusions

Regulated hydration of pollen is a key process for both pollination and self-incompatibility, and this is achieved by a balanced complex of hydration, dehydration and nutrient supply to pollen grains from stigmatic papilla cells.     

Neuropathic Pain in Rats with a Partial Sciatic Nerve Ligation Is Alleviated by Intravenous Injection of Monoclonal Antibody to High Mobility Group Box-1

High mobility group box-1 (HMGB1) is associated with the pathogenesis of inflammatory diseases. A previous study reported that intravenous injection of anti-HMGB1 monoclonal antibody significantly attenuated brain edema in a rat model of stroke, possibly by attenuating glial activation. Peripheral nerve injury leads to increased activity of glia in the spinal cord dorsal horn. Thus, it is possible that the anti-HMGB1 antibody could also be efficacious in attenuating peripheral nerve injury-induced pain. Following partial sciatic nerve ligation (PSNL), rats were treated with either anti-HMGB1 or control IgG. Intravenous treatment with anti-HMGB1 monoclonal antibody (2 mg/kg) significantly ameliorated PSNL-induced hind paw tactile hypersensitivity at 7, 14 and 21 days, but not 3 days, after ligation, whereas control IgG had no effect on tactile hypersensitivity. The expression of HMGB1 protein in the spinal dorsal horn was significantly increased 7, 14 and 21 days after PSNL; the efficacy of the anti-HMGB1 antibody is likely related to the presence of HMGB1 protein. Also, the injury-induced translocation of HMGB1 from the nucleus to the cytosol occurred mainly in dorsal horn neurons and not in astrocytes and microglia, indicating a neuronal source of HMGB1. Markers of astrocyte (glial fibrillary acidic protein (GFAP)), microglia (ionized calcium binding adaptor molecule 1 (Iba1)) and spinal neuron (cFos) activity were greatly increased in the ipsilateral dorsal horn side compared to the sham-operated side 21 days after PSNL. Anti-HMGB1 monoclonal antibody treatment significantly decreased the injury-induced expression of cFos and Iba1, but not GFAP. The results demonstrate that nerve injury evokes the synthesis and release of HMGB1 from spinal neurons, facilitating the activity of both microglia and neurons, which in turn leads to symptoms of neuropathic pain. Thus, the targeting of HMGB1 could be a useful therapeutic strategy in the treatment of chronic pain.     

Suppression of Alzheimer’s Disease-Related Phenotypes by Geranylgeranylacetone in Mice

Amyloid-β peptide (Aβ) plays an important role in the pathogenesis of Alzheimer’s disease (AD). Aβ is generated by the secretase-mediated proteolysis of β-amyloid precursor protein (APP), and cleared by enzyme-mediated degradation and phagocytosis. Transforming growth factor (TGF)-β1 stimulates this phagocytosis. We recently reported that the APP23 mouse model for AD showed fewer AD-related phenotypes when these animals were crossed with transgenic mice expressing heat shock protein (HSP) 70. We here examined the effect of geranylgeranylacetone, an inducer of HSP70 expression, on the AD-related phenotypes. Repeated oral administration of geranylgeranylacetone to APP23 mice for 9 months not only improved cognitive function but also decreased levels of Aβ, Aβ plaque deposition and synaptic loss. The treatment also up-regulated the expression of an Aβ-degrading enzyme and TGF-β1 but did not affect the maturation of APP and secretase activities. These outcomes were similar to those observed in APP23 mice genetically modified to overexpress HSP70. Although the repeated oral administration of geranylgeranylacetone did not increase the level of HSP70 in the brain, a single oral administration of geranylgeranylacetone significantly increased the level of HSP70 when Aβ was concomitantly injected directly into the hippocampus. Since geranylgeranylacetone has already been approved for use as an anti-ulcer drug and its safety in humans has been confirmed, we propose that this drug be considered as a candidate drug for the prevention of AD.     

Molecular analysis of NAD+-dependent xylitol dehydrogenase from the zygomycetous fungus Rhizomucor pusillus and reversal of the coenzyme preference

The zygomycetous fungus Rhizomucor pusillus NBRC 4578 is able to ferment not only d-glucose but also d-xylose into ethanol. Xylitol dehydrogenase from R. pusillus NBRC 4578 (RpXDH), which catalyzes the second step of d-xylose metabolism, was purified, and its enzymatic properties were characterized. The purified RpXDH preferred NAD⁺ as its coenzyme and showed substrate specificity for xylitol, d-sorbitol, and ribitol. cDNA cloning of xyl2 gene encoding RpXDH revealed that the gene included a coding sequence of 1,092?bp with a molecular mass of 39,185?kDa. Expression of the xyl2 in R. pusillus NBRC 4578 was induced by d-xylose, and the expression levels were increased with accumulation of xylitol. The xyl2 gene was expressed in Escherichia coli, and coenzyme preference of the recombinant RpXDH was reversed from NAD⁺ to NADP⁺ in the double mutant D205A/I206R by site-directed mutagenesis.     

Simultaneous Determination of Patulin and Penicillic Acid in Grains by Gas Chromatographic Method

Changes in aggregation and properties of alkali-treated soybean 7S and 11S globulins depend upon protein concentration during alkali-treatment. Such variables were investigated by viscosity, electrophoresis, circular dichroism, pulsed NMR, emulsion capacity and CaCl₂ precipitation measurements. In lower protein concentrations, the intrinsic viscosity decreased and the penetrative fractions into electrophoresis gel increased. The reduced contacts of proteins during neutralization resulted in smaller aggregates. Also specific fractions which were more sensitive to protein concentration on aggregation were observed for 11S globulin. The quantity of bound water depended only on pH at 7% concentration treatment. When the gel was formed, the bound water of protein increased, e.g., 0.085 g and 0.135 g/g protein at pH 10.6 and 13.2 treatment, respectively, whereas at 1% treatment, bound water showed almost no pH dependence (about 0.13 g/g protein). Furthermore, proteins prepared at higher protein concentrations were characterized by higher emulsion capacity and CaCI₂ precipitation ability. However, no protein concentration dependence was seen in the secondary structure of the aggregates.     

Disturbance of the Duration in the Menstrual Cycle under the Influence of Tight Clothing

We investigated the influence of skin pressure by clothing on the duration of menstrual cycle with 33 young adult women. The average age was 19.9 ± 2.1 years (mean ± SD), stature 159.5 ± 5.6cm and body mass 50.9 ± 5.5kg. Thirty-three women participated as subjects. They wore their usual clothing including foundation garments, panty stocking, pants or skirt and T-shirt or blouse and cardigan for the first 4 months from December to March (‘Tight 1’). For the second 4 months from April to July, the women wore loose clothes, i.e., they did not wear foundation garments at home. Skirt and jeans were worn loosely (‘Loose’). For the last 4 months, from August to November, they wore their clothes as tightly as possible, compared to ‘Tight 1’ (‘Tight 2’). Each participant marked the first day of the occurrence of menses in the pocket diary throughout the year. The main results were summarized as follows: 1) The average duration of the menstrual cycle was 44.2 ± 14.9 days (mean ±) in ‘Tight 1’, 30.4 ± 3.0 days in ‘Loose’ and 47.4 ± 22.7 days in ‘Tight 2’. 2) The number of months when the menses did not occur was 38 for ‘Tight 1’, 6 for ‘Loose’ and 40 for ‘Tight 2’. 3). The number of participants who had a duration of the menstrual cycles for more than 40 days, was 25 participants for ‘Tight’, 10 for ‘Loose’ and 29 for ‘Tight’. It can be concluded that skin pressure by clothing could disturb the duration in the menstrual cycle.