Effects of duration of exposure to ethylene on dormancy release in freesia corms

The exposure of freesia corms to ethylene (C₂H₄) at ca. 10 μl/l air for only 5 h was sufficient to promote sprouting, either under a closed system in which corms were treated in a sealed space of 3–10 1 or under a flow system in which corms were exposed to a continuous flow of air containing C₂H₄. Under the closed system, little change in corm response to C₂H₄ was found with increasing duration of exposure from 5 to 48 h, and the C0₂ concentration reached nearly 4% after 48 h. On the other hand, under the flow system, in which CO₂ did not accumulate above 0.1%, the promotive effect of C₂H₄ was diminished by extended exposure from 5 to 48 h.Repeated treatment with C₂H₄ for 23 h daily on 4 successive days resulted in the lowering of the promotive effect as compared with a single treatment, but repeated application of C₂H₄ for 5 h daily showed the same effect as a single application and gave a high sprouting rate similar to smoke treatment, independent of ambient temperature ranging from 25 to 35° C.Corms exposed to C₂H₄ for 5 h daily, or to smoke for 4 days, exhibited a better chilling response and advanced flowering.     

Electron microscopic cytochemical studies of anionic sites in the rat spleen

The distribution patterns of the intensity of negative charge on the free surfaces (glycocalyx of the plasma membrane) of endothelial cells (ECs) in blood vessels and reticular cells (RCs) in the splenic cord of the rat spleen were studied by an electron microscopic cytochemical method using polyethyleneimine (PEI) as a cationic probe. Spleens from adult male rats were perfusion-fixed with 0.5% glutaraldehyde -4% paraformaldehyde containing 0.05% cetylpyridinium chloride and then perfused with 0.5% PEI at pH 7.4. On the free surfaces (glycocalyx of the plasma membrane) of the ECs examined, distinct PEI-positive reactions were observed in blood vessels, such as trabecular arteries, central arteries, arterial capillaries, pulp veins and trabecular veins. These PEI-positive electron-dense substances in the trabecular arteries, central arteries, and trabecular veins took the shape of a band of 170-250 nm in thickness. On the other hand, the corresponding ultrastructure of the ECs lining the splenic sinuses and the RCs in the splenic cord showed exceedingly weak PEI reactions. The PEI-reactive deposits were significantly thinner than those in the above blood vessels. As the thickness of the electron-dense substances can be related to the density of the negative charge, these results suggest that there is a high intensity of negative charge on the free surfaces (glycocalyx of the plasma membrane) of ECs in blood vessels where blood cells and plasma pass into the red pulp or are discharged from the red pulp. In contrast, the splenic sinuses and RCs, which are the main components of the red pulp, contain weakly negative-charged sites. This may contribute to the microcirculation of the splenic blood vessels and elucidate the possible physiological functions of the spleen, such as blood storage.     

Inhibition of acetate ester biosynthesis in banana (Musa sapientum L.) fruit pulp under anaerobic conditions

The effect of anaerobic conditions on acetate ester biosynthesis in ripened banana pulp was investigated. Incubation of the pulp in less than 1% O(2) resulted in a significant reduction in the formation of ethyl acetate. Regardless of the presence of a large amount of endogenous ethanol and the remaining exogenous isobutyl alcohol after complete anaerobic incubation with the pulp, the production of acetate ester decreased. The effect of addition of pyruvate, isobutyl alcohol, acetate, and methyl hexanoate on acetate ester formation in 100% N(2) was also investigated. The addition of pyruvate and isobutyl alcohol to the pulp gave lower acetate esters in N(2) than in air, whereas the pulp incubated with acetate and isobutyl alcohol produced more acetate ester in both conditions. Therefore, the lack of acetyl CoA, or more precisely acetate, in the tissue is the main reason for the inhibition of acetate ester formation under anaerobic conditions. The activity of beta-oxidation measured by incubation with methyl hexanoate was detected only in the samples incubated in air. The formation of acetyl CoA, derived from pyruvate through mitochondria and through beta-oxidation, was inhibited by anaerobic conditions, which suggests that mitochondrial activity and/or beta-oxidation are essential for ester biosynthesis.     

Identification of two allelic IgG1 C(H) coding regions (Cgamma1) of cat

Two types of cDNA encoding IgG1 heavy chain (gamma1) were isolated from a single domestic short-hair cat. Sequence analysis indicated a higher level of similarity of these Cgamma1 sequences to human Cgamma1 sequence (76.9 and 77.0%) than to mouse sequence (70.0 and 69.7%) at the nucleotide level. Predicted primary structures of both the feline Cgamma1 genes, designated as Cgamma1a and Cgamma1b, were similar to that of human Cgamma1 gene, for instance, as to the size of constant domains, the presence of six conserved cysteine residues involved in formation of the domain structure, and the location of a conserved N-linked glycosylation site. Sequence comparison between the two alleles showed that 7 out of 10 nucleotide differences were within the C(H)3 domain coding region, all leading to nonsynonymous changes in amino acid residues. Partial sequence analysis of genomic clones showed three nucleotide substitutions between the two Cgamma1 alleles in the intron between the CH2 and C(H)3 domain coding regions. In 12 domestic short-hair cats used in this study, the frequency of Cgamma1a allele (62.5%) was higher than that of the Cgamma1b allele (37.5%).     

Analysis of mitochondrial DNA of an endangered beech species,Fagus hayatae Palibin ex Hayata

Mitochondrial DNA restriction fragment length polymorphisms were used to examine cytoplasmic diversity within a relic-like population of Fagus hayatae, located in northern Taiwan. Fifteen trees were surveyed for three restriction endonucleases (BamHI, EcoRI and HindIII) and five mitochondrial gene probes (atpA, atp6, atp9, coxI and coxII). The analysis failed to reveal any polymorphisms, an observation that suggests cytoplasmic uniformity in the F. hayatae population examined. It is also interesting to note that the chondriome type of our F. hayatae samples is very close to that characteristic of F. crenata populations in the southernmost area of Japan.     

基于MaxEnt和ArcGIS预测合欢潜在分布及适宜性评价

应用最大熵模型MaxEnt和地理信息系统ArcGIS,预测了合欢在我国的潜在适生区及其适生等级,为明确合欢在中国的潜在分布区和适宜性,及开展合欢种植区划和规范化栽培提供指导。结果表明:合欢潜在分布区主要位于华中、华南、华东和西南部分地区,主要适生省份为贵州、广西、广东、湖南、湖北、福建、江西、浙江、安徽(适生指数0.7);刀切法测试表明,最暖季降水量(模拟贡献率26.3%)、7月降雨量(25.2%)、年均温(13.5%)、最干季平均温(11.6%)、1月平均气温(10.8%)是影响合欢潜在分布的最主要5个环境因子。合欢最适生长地区主要集中在华中、华东2个地区。     

Development of late-bolting F<Subscript>1</Subscript> hybrids of Chinese cabbage (<Emphasis Type="Italic">Brassica rapa</Emphasis> L.) allowing early spring cultivation without heating

We developed new F₁ hybrids of Chinese cabbage (Brassica rapa L. ssp. pekinensis) that allow cultivation earlier in spring without heating by introducing extremely late-bolting alleles at two homologs of the flowering repressor Flowering Locus C (BrFLC2 and BrFLC3) from non-heading ‘Leafy Green Parental Line No. 2’. These new F₁ hybrids were produced by the following four steps. First, the extremely late bolting selected lines were developed. These selected lines headed in spring after overwintering cultivation, whereas the conventional F₁ cultivars flowered. Secondly, an investigation of the three plantings showed that our F₁ hybrids formed heads when seeds were sown from mid-February to early March, whereas the conventional F₁ cultivar did not form heads because of premature bolting. Thirdly, we identified some F₁ hybrids with extremely late bolting during early spring cultivation in an investigation of many F₁ hybrids. Finally, based on an investigation across four cold regions for 2 years, we compared the commercialization rate, defined as the proportion of plants greater than 2000 g in weight and with a flowering stalk less than 10 cm long. Then we identified a F₁ of MS02 × 12-04 which had a high commercialization rate on average (92%), whereas the rates of three conventional F₁ cultivars were only 0–2%. In the near future, these F₁ hybrids will be valuable late-bolting cultivars despite climate change, permitting stable cultivation and harvest over wide regions.