Role of isovaleroyl lipids in channeling of sound in the porpoise melon

Physical properties (e.g. specific gravity, adiabatic compressibility and sound velocity) of lipids isolated from tissues from contiguous areas of the fatty melon of an echo-locating porpoise (Delphinus delphis) were determined to elucidate relations between lipid composition and structure, and sound transmission in the head. Lipid content varied greatly within the melon (13.6–77.6% of the tissue weight) and triacylglycerols (80–100%) were the major lipid components. This lipid class was composed of diisovaleroylglycerides (triacylglycerols containing two isovaleroyl moieties and a long-chain acyl moiety), monoisovaleroyldiacylglycerols and triacylglycerols consisting of long-chain acids. The lipid-rich (>45%) areas in the melon contained a high proportion (>45% of total triacylglycerols) of diisovaleroylglycerides. There were gradations of sound velocities within the melon; the lowest sound velocities were associated with high concentrations of diisovaleroylglycerides (<1400 m/s) and the highest with high concentrations of long-chain triacylglycerols. Assuming an average sound frequency of 75 kHz, and considering dimensions of melon (path length and width of 12–14 cm and 5 cm, respectively), a forward radiating lobe of 15–25 degrees is produced. Thus, the deposition of lipids of different acoustic properties in a three-dimensional matrix within the porpoise melon results in a lens for the projection of sound into the marine environment.     

白兰瓜果实输入~(14)C-葡萄糖的转化与蔗糖合成

~(14)C 追踪试验结果表明,白兰瓜幼果中输入的~(14)C-葡萄糖,50%以上转化为稀酸水解和稀酸不水解的结构物质;果实发育后期,输入后48小时,在果肉和种子中分别只有18%和32%的~(14)C 参入结构物质。根据醇溶性糖的纸层析鉴定,幼果薄片渗入的~(14)C-葡萄糖仅转化为果糖,而发育后期果实则更多转化为蔗糖。显然,幼果的代谢模式是使物质和能量导向结构物质的形成;而后期果实生长已基本停止,物质代谢的方向又转向蔗糖合成的轨道上来。蔗糖合成底物试验结果表明,供给幼果不同底物都只有很低的蔗糖合成活性;发育后期果实供给UDPG+F-6-P 底物时可测出较高的蔗糖合成活性,初步推测白兰瓜中蔗糖合成主要是通过蔗糖磷酸酯合成酶来实现的。     

The use of hydrogen peroxide to control postharvest decay on 'Galia' melons

Sanosil-25, a disinfectant containing 48% hydrogen peroxide and silver salts as stabilising agents, inhibited the mycelial growth of the two main decays causing fungi of melons, Alternaria alternata and Fusarium solani in vitro at concentrations between 5000 and 10 000 μl litre^-1. However, in in vivo experiments, Sanosil-25 markedly decreased decay at a concentration of 5000 μl litre^-1 when incorporated into a wax treatment and produced no phytotoxic effect. This treatment may provide an alternative to imazalil which, although more effective, gives problems with residue levels. A concentration of 10 000 μl litre^-1 proved phytotoxic.     

瓜类刺盘孢诱导物对新疆甜瓜抗病相关酶活性的影响

近年来,应用病毒、细菌、真菌以及病原菌体及其代谢物作为诱导因子,已在多种作物上获得对病害的整体免疫,有些已开始在田间应用。我们也曾应用人工诱导免疫的方法使新疆甜瓜获得对瓜类疫霉病的抗性,但有关植物人工诱导免疫机理的研究,目前国外报道不多,国内尚未见报道。本文以瓜类刺盘孢(Colletotrichum langenarium)培养滤液和菌丝细胞壁作为诱导物,研究了免疫植株相关酶的活性以及可溶性蛋白的变化,探讨了人工诱导免疫的机理。     

白兰瓜子叶衰老过程中蔗糖酶同工酶的分离及其活性变化

利用DEAE—纤维素柱层析对白兰瓜子叶蔗糖酶同工酶进行了分离。发现细胞质可溶性部分含有4种蔗糖酶同工酶,其中3种为酸性蔗糖酶(Ⅰ、Ⅱ、Ⅲ),其活性最适pH分别为5.40、4.30和4.73;另外一种为碱性蔗糖酶,其最适pH为7.40。细胞壁盐溶性部分仅含1种酸性蔗糖酶,其最适pH亦为4.73。在白兰瓜子叶生长后期(7～11d),定位于细胞质的酸性蔗糖酶Ⅰ、Ⅱ和Ⅲ的活性略有升高;衰老发生后(17～23d)其活性显著下降;衰老后期碱性蔗糖酶活性消失。在子叶生长和衰老期间细胞壁酸性蔗糖酶活性则一直下降。     

Role of endogenous gibberellins in germination of melon (Cucumis melo) seeds

The effect of the plant growth retardants ancymidol. mefluidide and uniconazole on germination of two melon accessions differing in their ability to germinate at 14°C was examined. The accessions were the cold sensitive Noy Yizre'el and the cold tolerant Persia 202. The three growth retardants were able to delay the germination of intact Noy Yizre'el seeds, but did not affect that of intact Persia 202 seeds. On the other hand germination of decoated seeds of both accessions was unaffected by these inhibitors at normal oxygen concentration, but was inhibited at 5% oxygen. When gibberellin-like activity was measured by a dwarf rice biological assay following HPLC fractionation, it was found that seeds of Persia 202 contained much more gibberellin-like activity than Noy Yizre'el seeds. Among the extracted compounds several endogenous gibberellins were identified by combined gas chromatography-mass spectrometry (GC-MS). They included GA₄, GA₂₀, GA₁ and GA₃ in Noy Yizre'el and GA₃₄, GA₂₀, GA₁ and GA₈ in Persia 202. It is suggested that the better germination of intact Persia 202 seeds, compared to Noy Yizre'el seeds at low temperature and low oxygen concentration, is due to a higher endogenous level of GA and a better seed coat permeability to oxygen.     

Evaluation of restriction fragment length polymorphism in Cucumis melo

Summary The objectives of this study were to assess the degree of restriction fragment length polymorphism (RFLP) in Cucumis melo and to determine interrelationships among cultivated varieties. Initial screening of a genomic PstI library revealed that approximately 40% of the clones were repetitive. A total of 162 unique and low-copy sequence clones were hybridized to seven diverse accesions of C. melo and a C. sativus cultivar Pacer to evaluate RFLP variation. Of these, 130 probes (80%) detected a polymorphism between C. melo accessions and C. sativus, and the majority were polymorphic with more than one enzyme digest. In contrast, only 53 probes (33%) were useful in differentiating at least one of the seven accessions. Of those, only 9% were informative with more than one enzyme digest. This indicates that within C. melo, the differences among accessions are due to infrequent base substitutions, whereas between the two species, differences are mainly due to genome rearrangements such as insertions and deletions or numerous base substitutions. Of the informative probes, 34 were used in analyzing 44 C. melo lines to establish a data base of RFLP hybridization patterns. Percent similarity based on RFLP profiles was computed among lines and analyzed by principal component analysis, to visualize relationships among lines. There were clear demarcations among, but not within, muskmelon and honeydew groups.     

Genetic difference in somatic embryogenesis from seeds in melon (Cucumis melo L.)

Significant differences in somatic embryogenesis from melon seeds were observed among 18 cultivars; especially, cultivars Earl's Favorite and Barnett which produced a large number of somatic embryos. F₁ seeds were obtained by reciprocal crosses between cultivars. Some lines produced a large number of somatic embryos whereas others showed no or poor embryogenic response. Most of the F₁ seeds formed somatic embryos. The frequency of somatic embryogenesis decreased as compared to the parents with the highest potential. Transfer of the frequency of somatic embryogenesis from superior responding cultivars to inferior cultivars was proved. It was difficult to determine the mode of inheritance of somatic embryogenesis because there was a large variation in the range of somatic embryogenesis from F₂ seeds, and cytoplasmic effect was recognized in certain combinations.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - BAP 6-benzylaminopurine     

Einbau von 14C-mevalonsäurelacton in hopfenbitterstoffe

Labeled mevalonate is incorporated into terpenes and hop bitter compounds by Humulus lupulus. The role of mevalonate as a precursor for the prenyl (3-methyl-but-2-enyl) side chain of the hop bitter compounds is discussed.